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Sample records for geothermometers silica geothermometers

  1. Evaluation Of Chemical Geothermometers For Calculating Reservoir...

    Open Energy Info (EERE)

    Geothermometers For Calculating Reservoir Temperatures At Nevada Geothermal Power Plants Jump to: navigation, search OpenEI Reference LibraryAdd to library Conference Paper:...

  2. Silica Geothermometers | Open Energy Information

    Open Energy Info (EERE)

    in the Past 20 Years: Geochemistry in Geothermal Exploration, Resource Evaluation and Reservoir Management 2.0 2.1 Lectures on Geochemical Interpretation of Hydrothermal...

  3. New Improved Equations For Na-K, Na-Li And Sio2 Geothermometers...

    Open Energy Info (EERE)

    Improved Equations For Na-K, Na-Li And Sio2 Geothermometers By Outlier Detection And Rejection Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article:...

  4. Derivation and calibration of semi-empirical gas geothermometers for Mahanagdong Geothermal Project, Philippines

    SciTech Connect (OSTI)

    Sanchez, D.R.

    1996-12-31

    The dissolved CO{sub 2}, H{sub 2}S, and H{sub 2} gases in Mahanagdong aquifer fluids are controlled by specific gas-mineral equilibria. At temperature range of 250 to 310 {degrees}C, CO{sub 2} is buffered by clinozoisite + K-feldspar + calcite + muscovite (illite) + quartz mineral assemblage. For H{sub 2}S and H{sub 2} dissolved gases, they are more likely buffered by pyrrhotite + pyrite + magnetite mineral assemblage at similar temperature range. Calibration of five Mahanagdong (MG) gas geothermometers is presented, three of which used CO{sub 2}, H{sub 2}S, and H{sub 2} concentration in steam. The remaining two use CO{sub 2}/H{sub 2} and H{sub 2}S/H{sub 2} ratios. The calibration is based on the relation between gas content of drillhole discharges and measured aquifer temperatures. After establishing the gas content in the aquifer, gas concentrations were computed in steam after adiabatic boiling to atmospheric condition (100 {degrees}C), to obtain gas geothermometry functions. These functions could also be used in evaluating fraction of steam condensation and temperature of phase separation. A demonstration given the Mahanagdong fumarole data, indicates that there is generally a fair relation between computed temperatures using Mahanagdong gas geothermometers and the actual field trend`s temperatures.

  5. Geochemical Techniques | Open Energy Information

    Open Energy Info (EERE)

    Geothermometers Multicomponent Geothermometers Silica Geothermometers Thermal Ion Dispersion Thermochronometry References General References Technical References No exploration...

  6. Cation Geothermometers | Open Energy Information

    Open Energy Info (EERE)

    prospect the fastest is obtaining attractive chemical confirmation (geothermometry, gas analyses) that a thermal resource exists in that location. As with all geothermal...

  7. Multicomponent Geothermometers | Open Energy Information

    Open Energy Info (EERE)

    of using full chemical analyses of water samples to compute the saturation indices (log(QK)) of reservoir minerals over a range of temperatures. The saturation indices are graphed...

  8. Chemical Geothermometers And Mixing Models For Geothermal Systems...

    Open Energy Info (EERE)

    to outline favorable places to explore for geothermal energy. Some of the qualitative methods, such as the delineation of mercury and helium anomalies in soil gases, do not...

  9. Cation Geothermometers At Lightning Dock Geothermal Area (Witcher...

    Open Energy Info (EERE)

    Usefulness useful DOE-funding Unknown Exploration Basis Part of the Geothermal Resource Evaluation and Definition (GRED) Program administered by DOE-AAO under Cooperative...

  10. A New Improved Na-K Geothermometer By Artificial Neural Networks...

    Open Energy Info (EERE)

    567-577), Truesdell (1975; Proc. 2nd UN Symposium), Tonani (1980; Proc. Adv. Eur. Geoth. Research, 2nd Symposium), Fournier (1979a; J. Volcanol. Geotherm. Res. 5, 1-16), Nieva and...

  11. An Empirical Na-K-Ca Geothermometer For Natural Waters | Open...

    Open Energy Info (EERE)

    temperature environments ranging from 4 to 340C. The data for most geothermal waters cluster near a straight line when plotted as the function vs reciprocal of absolute...

  12. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    (2) electrons (2) elements (2) geothermal energy (2) geothermometers (2) ... are useful for estimating geothermal reservoir temperatures, though a ...

  13. Property:HydroInfo | Open Energy Information

    Open Energy Info (EERE)

    Multicomponent Geothermometers N Near Infrared Surveys O Oblique Aerial & Ground Visible Band & Thermographic Imaging Over Core Stress P Paleomagnetic Measurements...

  14. Geothermometry At Coso Geothermal Area (1980) | Open Energy Informatio...

    Open Energy Info (EERE)

    DOE-funding Unknown Exploration Basis Fluid temperature of feed water Notes Cation and sulfate isotope geothermometers indicate that the reservoir feeding water to the Coso Hot...

  15. Geochemistry of the Wendel-Amedee Geothermal System-California...

    Open Energy Info (EERE)

    have been identified based on the concentrations of the conservative elements C1 and B, fluid enthalpies, and the application of chemical geothermometers. One is characterized by...

  16. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    (2) electron precipitation (2) electron temperature (2) electrons (2) elements (2) geothermal energy (2) geothermometers (2) geothermometry (2) magnetic fields (2) measuring ...

  17. Geothermometry At Teels Marsh Area (Coolbaugh, Et Al., 2006)...

    Open Energy Info (EERE)

    useful DOE-funding Unknown Notes Follow up (to ASTER satellite imaging) analysis of spring and well waters yielded geothermometer reservoir estimates up to 192C References...

  18. Geothermometry At Rhodes Marsh Area (Coolbaugh, Et Al., 2006...

    Open Energy Info (EERE)

    useful DOE-funding Unknown Notes Follow up (to ASTER satellite imaging) analysis of spring and well waters yielded geothermometer reservoir estimates up to 162C References...

  19. Property:StratInfo | Open Energy Information

    Open Energy Info (EERE)

    Microhole Array Multicomponent Geothermometers N Near Infrared Surveys O Oblique Aerial & Ground Visible Band & Thermographic Imaging Observation Wells Over Core Stress P...

  20. Property:LithologyInfo | Open Energy Information

    Open Energy Info (EERE)

    Geothermometers N Near Infrared Surveys Numerical Modeling O Oblique Aerial & Ground Visible Band & Thermographic Imaging Observation Wells Over Core Stress P PSInSAR...

  1. Multifunctional mesoporous silica catalyst

    DOE Patents [OSTI]

    Lin, Victor Shang-Yi; Tsai, Chih-Hsiang; Chen, Hung-Ting; Pruski, Marek; Kobayashi, Takeshi

    2015-03-31

    The present invention provides bifunctional silica mesoporous materials, including mesoporous silica nanoparticles ("MSN"), having pores modified with diarylammonium triflate and perfluoroaryl moieties, that are useful for the acid-catalyzed esterification of organic acids with organic alcohols.

  2. Silica extraction from geothermal water

    DOE Patents [OSTI]

    Bourcier, William L; Bruton, Carol J

    2014-09-23

    A method of producing silica from geothermal fluid containing low concentration of the silica of less than 275 ppm includes the steps of treating the geothermal fluid containing the silica by reverse osmosis treatment thereby producing a concentrated fluid containing the silica, seasoning the concentrated fluid thereby producing a slurry having precipitated colloids containing the silica, and separating the silica from the slurry.

  3. Silica Scaling Removal Process

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Scaling Removal Process Scientists at Los Alamos National Laboratory have developed a novel technology to remove both dissolved and colloidal silica using small gel particles....

  4. Silica Deposition | Open Energy Information

    Open Energy Info (EERE)

    silica precipitating out of solution. Geothermal fluids are often silica rich and as the temperature of the fluids cool when they reach the surface silica precipitates out of the...

  5. Trace Element Geochemical Zoning in the Roosevelt Hot Springs...

    Open Energy Info (EERE)

    this distribution may be a useful solid geothermometer. Authors O.D. Christensen, J.N. Moore and R.M. Capuano Conference GRC Annual Meeting; Salt Lake City, UT; 09091980...

  6. Colorado thermal spring water geothermometry (public dataset...

    Open Energy Info (EERE)

    chemical geothermometers for Colorado thermal springs. Data citations include Barrett, J. K. and Pearl, R. H. (1976), George, R. D., Curtis, H. A., Lester, O. C., Crook, J. K.,...

  7. Chemistry Of Thermal And Nonthermal Springs In The Vicinity Of...

    Open Energy Info (EERE)

    depths. Thermal waters at Drakesbad and in Little Hot Springs Valley have neutral-pH, low-Cl concentrations and have estimated Na-K-Ca and Na-Li geothermometer temperatures...

  8. Advective (heat sweep) geothermal systems | Open Energy Information

    Open Energy Info (EERE)

    temperatures can be predicted from the unchecked application of cation-based Na-K-Ca geo-thermometers. This study shows that in half of the prospects fully equilibrated...

  9. Kinetics of silica polymerization

    SciTech Connect (OSTI)

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  10. Silica Precipitation and Lithium Sorption

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Jay Renew

    2015-09-20

    This file contains silica precipitation and lithium sorption data from the project. The silica removal data is corrected from the previous submission. The previous submission did not take into account the limit of detection of the ICP-MS procedure.

  11. Stabilized fuel with silica support structure

    SciTech Connect (OSTI)

    Poco, J.F.; Hrubesh, L.W.

    1991-12-31

    This report describes a stabilized fuel which is supported by a silica support structure. The silica support structure provides a low density, high porosity vehicle for safely carrying hydrocarbon fuels. The silica support structure for hydrocarbon fuel does not produce toxic material residues on combustion which would pose environmentally sensitive disposal problems. The silica stabilized fuel composition is useful as a low temperature, continuous burning fire starter for wood or charcoal.

  12. Removal of dissolved and colloidal silica

    DOE Patents [OSTI]

    Midkiff, William S.

    2002-01-01

    Small amorphous silica particles are used to provide a relatively large surface area upon which silica will preferentially adsorb, thereby preventing or substantially reducing scaling caused by deposition of silica on evaporative cooling tower components, especially heat exchange surfaces. The silica spheres are contacted by the cooling tower water in a sidestream reactor, then separated using gravity separation, microfiltration, vacuum filtration, or other suitable separation technology. Cooling tower modifications for implementing the invention process have been designed.

  13. Cellular membrane trafficking of mesoporous silica nanoparticles

    SciTech Connect (OSTI)

    Fang, I-Ju

    2012-06-21

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine the specific organelle that mesoporous silica nanoparticles could approach via the identification of harvested proteins from exocytosis process. Based on the study of endo- and exocytosis behavior of mesoporous silica nanoparticle materials, we can design smarter drug delivery vehicles for cancer therapy that can be effectively controlled. The destination, uptake efficiency and the cellular distribution of mesoporous silica nanoparticle materials can be programmable. As a result, release mechanism and release rate of drug delivery systems can be a well-controlled process. The deep investigation of an endo- and exocytosis study of mesoporous silica nanoparticle materials promotes the development of drug delivery applications.

  14. Non-destructively shattered mesoporous silica for protein drug...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Non-destructively shattered mesoporous silica for protein drug delivery Citation Details In-Document Search Title: Non-destructively shattered mesoporous silica ...

  15. Synthesis of very small diameter silica nanofibers using sound...

    Office of Scientific and Technical Information (OSTI)

    silica nanofibers using sound waves Citation Details In-Document Search Title: Synthesis of very small diameter silica nanofibers using sound waves Authors: Sharma, ...

  16. Effect of Bubbles and Silica Dissolution on Melter Feed Rheology...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Effect of Bubbles and Silica Dissolution on Melter Feed Rheology during Conversion to Glass Citation Details In-Document Search Title: Effect of Bubbles and Silica ...

  17. Coagulation chemistries for silica removal from cooling tower...

    Office of Scientific and Technical Information (OSTI)

    Coagulation chemistries for silica removal from cooling tower water. Citation Details In-Document Search Title: Coagulation chemistries for silica removal from cooling tower water. ...

  18. Addressable morphology control of silica structures by manipulating...

    Office of Scientific and Technical Information (OSTI)

    Addressable morphology control of silica structures by manipulating the reagent addition time Citation Details In-Document Search Title: Addressable morphology control of silica ...

  19. Flue gas injection control of silica in cooling towers. (Technical...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Flue gas injection control of silica in cooling towers. Citation Details In-Document Search Title: Flue gas injection control of silica in cooling towers. ...

  20. Sample Desorption/Onization From Mesoporous Silica

    DOE Patents [OSTI]

    Iyer, Srinivas (Los Alamos, NM); Dattelbaum, Andrew M. (Los Alamos, NM)

    2005-10-25

    Mesoporous silica is shown to be a sample holder for laser desorption/ionization of mass spectrometry. Supported mesoporous silica was prepared by coating an ethanolic silicate solution having a removable surfactant onto a substrate to produce a self-assembled, ordered, nanocomposite silica thin film. The surfactant was chosen to provide a desired pore size between about 1 nanometer diameter and 50 nanometers diameter. Removal of the surfactant resulted in a mesoporous silica thin film on the substrate. Samples having a molecular weight below 1000, such as C.sub.60 and tryptophan, were adsorbed onto and into the mesoporous silica thin film sample holder and analyzed using laser desorption/ionization mass spectrometry.

  1. Geothermometry At Lassen Volcanic National Park Area (Janik ...

    Open Energy Info (EERE)

    sample taken had a pH of 8.35 and contained 2100 ppm Cl and 0.55 ppm NH3. Ratios of Na+K+ and Na+Cl remained nearly constant throughout the flow test. Cation geothermometers...

  2. Modification of silica gel by organotitanium compounds

    SciTech Connect (OSTI)

    Khrustaleva, E.A.; Abramova, V.I.; Suvorov, A.L.; Fridman, L.I.

    1988-05-10

    The study of the modification of silica gels by various organotitanium compounds (OTC) is of interest in connection with their possible use as specific adsorbents, catalysts in the preparation of filled polymeric materials. The authors studied the modification of silica gel by OTC of different types in order to obtain reactive functional organic groups bound to titanium atoms on its surface. During treatment of silica gel with organotitanium compounds of different types in an organic solvent, these react chemically with the hydroxylic groups of silica gel to form Si-O-Ti groups on the surface, containing organic radicals bound to the titanium atom. In the case of coordinatively unsaturated OTC, increase in the time of interaction of the components on heating and excess OTC lead to partial splitting of the Si-O-Ti bonds, which is not observed for coordinatively saturated OTC.

  3. The Management of Silica in Los Alamos National Laboratory Tap Water - A Study of Silica Solubility

    SciTech Connect (OSTI)

    Wohlberg, C.; Worland, V.P.; Kozubal, M.A.; Erickson, G.F.; Jacobson, H.M.; McCarthy, K.T.

    1999-07-01

    Well water at Los Alamos National Laboratory (LANL) has a silica (SiO{sub 2}) content of 60 to 100 mg/L, with 4 mg/L of magnesium, 13 mg/L calcium and lesser concentrations of other ions. On evaporation in cooling towers, when the silica concentration reaches 150 to 220 mg/L, silica deposits on heat transfer surfaces. When the high silica well water is used in the reprocessing of plutonium, silica remains in solution at the end of the process and creates a problem of removal from the effluent prior to discharge or evaporation. The work described in this Report is divided into two major parts. The first part describes the behavior of silica when the water is evaporated at various conditions of pH and in the presence of different classes of anions: inorganic and organic. In the second part of this work it was found that precipitation (floccing) of silica was a function of solution pH and mole ratio of metal to silica.

  4. High resolution patterning of silica aerogels

    SciTech Connect (OSTI)

    Bertino, M.F.; Hund, J.F.; Sosa, J.; Zhang, G.; Sotiriou-Leventis, C.; Leventis, N.; Tokuhiro, A.T.; Terry, J. (UMR-MUST); (IIT)

    2008-10-30

    Three-dimensional metallic structures are fabricated with high spatial resolution in silica aerogels. In our method, silica hydrogels are prepared with a standard base-catalyzed route, and exchanged with an aqueous solution typically containing Ag{sup +} ions (1 M) and 2-propanol (0.2 M). The metal ions are reduced photolytically with a table-top ultraviolet lamp, or radiolytically, with a focused X-ray beam. We fabricated dots and lines as small as 30 x 70 {micro}m, protruding for several mm into the bulk of the materials. The hydrogels are eventually supercritically dried to yield aerogels, without any measurable change in the shape and spatial resolution of the lithographed structures. Transmission electron microscopy shows that illuminated regions are composed by Ag clusters with a size of several {micro}m, separated by thin layers of silica.

  5. Mesoporous-silica films, fibers, and powders by evaporation ...

    Office of Scientific and Technical Information (OSTI)

    Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution ...

  6. Flue gas injection control of silica in cooling towers. (Technical...

    Office of Scientific and Technical Information (OSTI)

    Flue gas injection control of silica in cooling towers. Citation Details In-Document Search Title: Flue gas injection control of silica in cooling towers. You are accessing a ...

  7. Kinetics of silica-phase transitions

    SciTech Connect (OSTI)

    Duffy, C.J.

    1993-07-01

    In addition to the stable silica polymorph quartz, several metastable silica phases are present in Yucca Mountain. The conversion of these phases to quartz is accompanied by volume reduction and a decrease in the aqueous silica activity, which may destabilize clinoptilolite and mordenite. The primary reaction sequence for the silica phases is from opal or glass to disordered opal-CT, followed by ordering of the opal-CT and finally by the crystallization of quartz. The ordering of opal-CT takes place in the solid state, whereas the conversion of opal-CT takes place through dissolution-reprecipitation involving the aqueous phase. It is proposed that the rate of conversion of opal-CT to quartz is controlled by diffusion of defects out of a disordered surface layer formed on the crystallizing quartz. The reaction rates are observed to be dependent on temperature, pressure, degree of supersaturation, and pH. Rate equations selected from the literature appear to be consistent with observations at Yucca Mountain.

  8. Molecular sieving silica membrane fabrication process

    DOE Patents [OSTI]

    Raman, N.K.; Brinker, C.J.

    1999-08-10

    A process is described for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film. 11 figs.

  9. Molecular sieving silica membrane fabrication process

    DOE Patents [OSTI]

    Raman, Narayan K. (Monroeville, PA); Brinker, Charles Jeffrey (Albuquerque, NM)

    1999-01-01

    A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.

  10. Molecular sieving silica membrane fabrication process

    DOE Patents [OSTI]

    Raman, Narayan K.; Brinker, Charles Jeffrey

    1998-01-01

    A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.

  11. Significant Silica Solubility in Geothermal Steam

    SciTech Connect (OSTI)

    James, Russell

    1986-01-21

    Although it is widely believed that silica solubility in low pressure (5 to 10 bar) geothermal steam is negligible, when one takes into account steam flows exceeding 10 million tonnes a year--at Wairakei, for instance--it is found that the amount transmitted in the vapor has the potential to give significant deposits on turbine nozzles and blades. A 150 MWe power station, when based on flows from a hot water reservoir at (a) 250 C or (b) 315 C, and with separator pressures of 6 bar, is found to carry about 100 and 200 kg/year respectively in the steam phase. In the case of a similar sized station exploiting a dry steam reservoir such as The Geysers, equivalent silica flows are obtained, dissolved in steam and carried as dust--the latter as solid particles precipitating from the vapor en route from source to turbine, and not preexisting in the formations as is commonly considered. Choking or coating of subterranean rock near such dry steam wells due to exsolving silica, may be the principal cause of declining steam discharge under production. Silica from completely dry or superheated steam can also seal the cap and sides of steam reservoirs when expanding below the criticus temperature (236 C) in a way previously thought possible only by hot water or wet steam.

  12. Conversion of geothermal waste to commercial products including silica

    DOE Patents [OSTI]

    Premuzic, Eugene T.; Lin, Mow S.

    2003-01-01

    A process for the treatment of geothermal residue includes contacting the pigmented amorphous silica-containing component with a depigmenting reagent one or more times to depigment the silica and produce a mixture containing depigmented amorphous silica and depigmenting reagent containing pigment material; separating the depigmented amorphous silica and from the depigmenting reagent to yield depigmented amorphous silica. Before or after the depigmenting contacting, the geothermal residue or depigmented silica can be treated with a metal solubilizing agent to produce another mixture containing pigmented or unpigmented amorphous silica-containing component and a solubilized metal-containing component; separating these components from each other to produce an amorphous silica product substantially devoid of metals and at least partially devoid of pigment. The amorphous silica product can be neutralized and thereafter dried at a temperature from about 25.degree. C. to 300.degree. C. The morphology of the silica product can be varied through the process conditions including sequence contacting steps, pH of depigmenting reagent, neutralization and drying conditions to tailor the amorphous silica for commercial use in products including filler for paint, paper, rubber and polymers, and chromatographic material.

  13. Silica substrate or portion formed from oxidation of monocrystalline silicon

    DOE Patents [OSTI]

    Matzke, Carolyn M.; Rieger, Dennis J.; Ellis, Robert V.

    2003-07-15

    A method is disclosed for forming an inclusion-free silica substrate using a monocrystalline silicon substrate as the starting material and oxidizing the silicon substrate to convert it entirely to silica. The oxidation process is performed from both major surfaces of the silicon substrate using a conventional high-pressure oxidation system. The resulting product is an amorphous silica substrate which is expected to have superior etching characteristics for microfabrication than conventional fused silica substrates. The present invention can also be used to convert only a portion of a monocrystalline silicon substrate to silica by masking the silicon substrate and locally thinning a portion the silicon substrate prior to converting the silicon portion entirely to silica. In this case, the silica formed by oxidizing the thinned portion of the silicon substrate can be used, for example, as a window to provide optical access through the silicon substrate.

  14. Carbon nanomaterials in silica aerogel matrices

    SciTech Connect (OSTI)

    Hamilton, Christopher E [Los Alamos National Laboratory; Chavez, Manuel E [Los Alamos National Laboratory; Duque, Juan G [Los Alamos National Laboratory; Gupta, Gautam [Los Alamos National Laboratory; Doorn, Stephen K [Los Alamos National Laboratory; Dattelbaum, Andrew M [Los Alamos National Laboratory; Obrey, Kimberly A D [Los Alamos National Laboratory

    2010-01-01

    Silica aerogels are ultra low-density, high surface area materials that are extremely good thermal insulators and have numerous technical applications. However, their mechanical properties are not ideal, as they are brittle and prone to shattering. Conversely, single-walled carbon nanotubes (SWCNTs) and graphene-based materials, such as graphene oxide, have extremely high tensile strength and possess novel electronic properties. By introducing SWCNTs or graphene-based materials into aerogel matrices, it is possible to produce composites with the desirable properties of both constituents. We have successfully dispersed SWCNTs and graphene-based materials into silica gels. Subsequent supercritical drying results in monolithic low-density composites having improved mechanical properties. These nanocomposite aerogels have great potential for use in a wide range of applications.

  15. Light-scattering studies of silica aerogels

    SciTech Connect (OSTI)

    Hunt, A.J.

    1983-02-01

    Due to its combination of transparency and low thermal conductivity, aerogel holds considerable promise for use as insulating window materials for residential and commercial applications. This paper reports on the preliminary investigation of the optical and scattering properties of silica aerogels. It briefly describes the properties of aerogels important for window glazing applications. The optical properties are then described, followed by a discussion of the scattering measurements and their interpretation.

  16. Stabilization of Colloidal Silica Using Small Polyols

    SciTech Connect (OSTI)

    GULLEY, GERALD L.; MARTIN, JAMES E.

    1999-09-07

    We have discovered that small polyols are reasonably effective at stabilizing colloidal silica against aggregation, even under the conditions of high pH and salt concentration. Both quasielastic and elastic light scattering were used to show that these polyols dramatically decrease the aggregation rate of the suspension, changing the growth kinetics from diffusion-limited cluster-cluster aggregation to reaction-limited cluster-cluster aggregation. These polyols maybe useful in the treatment of tank wastes at the Hanford site.

  17. Silica powders for powder evacuated thermal insulating panel and method

    DOE Patents [OSTI]

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1996-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  18. Silica powders for powder evacuated thermal insulating panel and method

    DOE Patents [OSTI]

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1994-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2 /g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  19. Silica powders for powder evacuated thermal insulating panel and method

    DOE Patents [OSTI]

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1995-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  20. Silica powders for powder evacuated thermal insulating panel and method

    DOE Patents [OSTI]

    Harris, M.T.; Basaran, O.A.; Kollie, T.G.; Weaver, F.J.

    1996-01-02

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm{sup 3} and an external surface area in the range of about 90 to 600 m{sup 2}/g is described. The silica powders are prepared by reacting a tetraalkyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders. 2 figs.

  1. Methods of coping with silica deposition - the PNOC experience

    SciTech Connect (OSTI)

    Candelaria, M.N.R.; Garcia, S.E.; Baltazar, A.D.J. Jr.; Solis, R.P.

    1996-12-31

    Several methods of coping with silica deposition from geothermal waters have been undertaken by PNOC-EDC to maximize Power Output from these fluids. Initially, the problem of amorphous silica deposition in surface pipelines and the reinjection well was prevented by operating the production separators at pressures higher or equal to amorphous silica saturation. However, increasing demands for additional power and stringent environmental controls have dictated the need to find alternative methods of coping with silica deposition. Several options have been studied and tested to be able to optimize fluid utilization for production. These include: acid treatment polymerization and deposition of silica in surface ponds or sumps, and chemical inhibition. As each brine is unique, methodologies used for mitigation of the silica problem have been varied.

  2. Controlled Release from Core-Shell Nanoporous Silica Particles for

    Office of Scientific and Technical Information (OSTI)

    Corrosion Inhibition of Aluminum Alloys (Journal Article) | SciTech Connect Journal Article: Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys Citation Details In-Document Search Title: Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys Cerium (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted

  3. Improvements in geothermal electric power and silica production

    DOE Patents [OSTI]

    Hill, J.H.; Fulk, M.M.

    Electricity is generated from hot geothermal solution by extracting heat therefrom, mineral solids which form in a so cooled geothermal solution are separated to recover minerals and facilitate reinjection of the solution into the ground. The separated solids are treated to recover silica by addition of an acid (amorphous silica precipitates) or a base (other minerals precipitate and soulble silicates are formed which are subsequently precipitated by acid neutralization). If desired, after silica is separated, other minerals can be separated and recovered.

  4. Treatment of Difficult Waters: Arsenic Removal Silica Control...

    Office of Scientific and Technical Information (OSTI)

    of Difficult Waters: Arsenic Removal Silica Control Carbon Capture and Enhanced Oil Recovery. Brady, Patrick Vane Abstract not provided. Sandia National Laboratories...

  5. Treatment of Difficult Waters: Arsenic Removal Silica Control...

    Office of Scientific and Technical Information (OSTI)

    of Difficult Waters: Arsenic Removal Silica Control Carbon Capture and Enhanced Oil Recovery. Citation Details In-Document Search Title: Treatment of Difficult Waters:...

  6. Operating Experience Level 3, Dangers of Respirable Silica |...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (OE-3) document provides information on a safety concern related to recurring worker exposure to dust containing crystalline silica at Department of Energy (DOE) sites. OE-3...

  7. Probing the Silica/Polysiloxane Interface: A Solid State NMR...

    Office of Scientific and Technical Information (OSTI)

    of y-Irradiated Composite Materials Citation Details In-Document Search Title: Probing the SilicaPolysiloxane Interface: A Solid State NMR Investigation of y-Irradiated ...

  8. Controlled Release from Core-Shell Nanoporous Silica Particles...

    Office of Scientific and Technical Information (OSTI)

    Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys Citation Details In-Document Search Title: Controlled Release from Core-S...

  9. Particle Restabilization in Silica/PEG/Ethanol Suspensions: How...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Particle Restabilization in SilicaPEGEthanol Suspensions: How Strongly do Polymers Need To Adsorb To Stabilize Against ...

  10. Coagulation chemistries for silica removal from cooling tower...

    Office of Scientific and Technical Information (OSTI)

    removal from cooling tower water. Citation Details In-Document Search Title: Coagulation chemistries for silica removal from cooling tower water. You are accessing a ...

  11. Fibrous composites comprising carbon nanotubes and silica

    DOE Patents [OSTI]

    Peng, Huisheng; Zhu, Yuntian Theodore; Peterson, Dean E.; Jia, Quanxi

    2011-10-11

    Fibrous composite comprising a plurality of carbon nanotubes; and a silica-containing moiety having one of the structures: (SiO).sub.3Si--(CH.sub.2).sub.n--NR.sub.1R.sub.2) or (SiO).sub.3Si--(CH.sub.2).sub.n--NCO; where n is from 1 to 6, and R.sub.1 and R.sub.2 are each independently H, CH.sub.3, or C.sub.2H.sub.5.

  12. Community Geothermal Technology Program: Silica bronze project. Final report

    SciTech Connect (OSTI)

    Bianchini, H.

    1989-10-01

    Objective was to incorporate waste silica from the HGP-A geothermal well in Pohoiki with other refractory materials for investment casting of bronze sculpture. The best composition for casting is about 50% silica, 25% red cinders, and 25% brick dust; remaining ingredient is a binder, such as plaster and water.

  13. Temperature measurements of shocked silica aerogel foam

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Falk, K.; McCoy, C. A.; Fryer, C. L.; Greeff, C. W.; Hungerford, A. L.; Montgomery, D. S.; Schmidt, D. W.; Sheppard, D. G.; Williams, J. R.; Boehly, T. R.; et al

    2014-09-12

    We present recent results of equation-of-state (EOS) measurements of shocked silica (SiO2) aerogel foam at the OMEGA laser facility. Silica aerogel is an important low-density pressure standard used in many high energy density experiments, including the novel technique of shock and release. Due to its many applications, it has been a heavily studied material and has a well-known Hugoniot curve. This work then complements the velocity and pressure measurements with additional temperature data providing the full EOS information within the warm dense matter regime for the temperature interval of 1–15 eV and shock velocities between 10 and 40 km/s correspondingmore » to shock pressures of 0.3–2 Mbar. The experimental results were compared with hydrodynamic simulations and EOS models. We found that the measured temperature was systematically lower than suggested by theoretical calculations. As a result, simulations provide a possible explanation that the emission measured by optical pyrometry comes from a radiative precursor rather than from the shock front, which could have important implications for such measurements.« less

  14. Ambient-pressure silica aerogel films

    SciTech Connect (OSTI)

    Prakash, S.S. [New Mexico Univ., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States); Hurd, A.J. [Sandia National Labs., Albuquerque, NM (United States)

    1994-12-31

    Very highly porous (aerogel) silica films with refractive index in the range 1.006--1.05 (equivalent porosity 98.5--88%) were prepared by an ambient-pressure process. It was shown earlier using in situ ellipsometric imaging that the high porosity of these films was mainly attributable to the dilation or `springback` of the film during the final stage of drying. This finding was irrefutably reconfirmed by visually observing a `springback` of >500% using environmental scanning electron microscopy (ESEM). Ellipsometry and ESEM also established the near cent per cent reversibility of aerogel film deformation during solvent intake and drying. Film thickness profile measurements (near the drying line) for the aerogel, xerogel and pure solvent cases are presented from imaging ellipsometry. The thickness of these films (crack-free) were controlled in the range 0.1-3.5 {mu}m independent of refractive index.

  15. Laser Damage Precursors in Fused Silica

    SciTech Connect (OSTI)

    Miller, P; Suratwala, T; Bude, J; Laurence, T A; Shen, N; Steele, W A; Feit, M; Menapace, J; Wong, L

    2009-11-11

    There is a longstanding, and largely unexplained, correlation between the laser damage susceptibility of optical components and both the surface quality of the optics, and the presence of near surface fractures in an optic. In the present work, a combination of acid leaching, acid etching, and confocal time resolved photoluminescence (CTP) microscopy has been used to study laser damage initiation at indentation sites. The combination of localized polishing and variations in indentation loads allows one to isolate and characterize the laser damage susceptibility of densified, plastically flowed and fractured fused silica. The present results suggest that: (1) laser damage initiation and growth are strongly correlated with fracture surfaces, while densified and plastically flowed material is relatively benign, and (2) fracture events result in the formation of an electronically defective rich surface layer which promotes energy transfer from the optical beam to the glass matrix.

  16. Grafting Sulfated Zirconia on Mesoporous Silica

    SciTech Connect (OSTI)

    Wang, Yong; Lee, Kwan Young; Choi, Saemin; Liu, Jun; Wang, Li Q.; Peden, Charles HF

    2007-06-01

    Sulfated zirconia has received considerable attention as a potential solid acid catalyst in recent years. In this paper, the preparation and properties of acid catalysts obtained by grafting ziconia with atomic precision on MCM-41 mesoporous silica were studied. TEM and potential titration characterizations revealed that ZrO2/MCM-41 with monolayer coverage can be obtained using this grafting technique. Sulfated ZrO2/MCM-41 exhibits improved thermal stability than that of bulk sulfated zirconia, as evidenced by temperature programmed characterizations and XRD analysis. Temperature programmed reaction of isopropanol was used to evaluate the acidity of sulfated ZrO2/MCM-41. It was found that the acid strength of sulfated ZrO2/MCM-41 with monolayer coverage is weaker than bulk sulfated zirconia but stronger than SiO2-Al2O3, a common strong acid catalyst.

  17. Development of Filler Structure in Colloidal Silica-Polymer Nanocomposites

    SciTech Connect (OSTI)

    Meth, Jeffrey S; Zane, Stephen G; Chi, Changzai; Londono, J David; Wood, Barbara A; Cotts, Patricia; Keating, Mimi; Guise, William; Weigand, Steven

    2012-02-07

    The realization of the full potential for polymeric nanocomposites to manifest their entitled property improvements relies, for some properties, on the ability to achieve maximum particle-matrix interfacial area. Well-dispersed nanocomposites incorporating colloidal silica as the filler can be realized in both polystyrene and poly(methyl methacrylate) matrices by exploiting the charge stabilized nature of silica in nonaqueous solvents which act as Bronsted bases. We demonstrate that dispersions of colloidal silica in dimethylformamide are charge stabilized, regardless of organosilyl surface functionalization. When formulated with polymer solutions, the charge stabilized structure is maintained during drying until the charged double layer collapses. Although particles are free to diffuse and cluster after this neutralization, increased matrix viscosity retards the kinetics. We demonstrate how high molecular weight polymers assist in immobilizing the structure of the silica to produce well-dispersed composites. The glass transition temperatures of these composites do not vary, even at loadings up to 50 vol %.

  18. Probing warm-dense Silica with LCLS and betatron radiation

    SciTech Connect (OSTI)

    Kotick, Jordan

    2015-08-27

    In this paper, a study of Silica is presented using a novel X-ray probe. The value of this X-ray source will be clearly defined, and diagnostic results will be presented.

  19. A novel synthesis of micrometer silica hollow sphere

    SciTech Connect (OSTI)

    Pan Wen; Ye Junwei [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Zhongshan Road 158-43, Dalian 116012 (China); Ning Guiling [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Zhongshan Road 158-43, Dalian 116012 (China)], E-mail: ninggl@dlut.edu.cn; Lin Yuan; Wang Jing [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Zhongshan Road 158-43, Dalian 116012 (China)

    2009-02-04

    Silica microcapsules (hollow spheres) were synthesized successfully by a novel CTAB-stabilized water/oil emulsion system mediated hydrothermal method. The addition of urea to a solution of aqueous phase was an essential step of the simple synthetic procedure of silica hollow spheres, which leads to the formation of silica hollow spheres with smooth shell during hydrothermal process. The intact hollow spheres were obtained by washing the as-synthesized solid products with distilled water to remove the organic components. A large amount of silanol groups were retained in the hollow spheres by this facile route without calcination. The morphologies and optical properties of the product were characterized by transmission electron microscopy, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. Furthermore, on the basis of a series of SEM observations, phenomenological elucidation of a mechanism for the growth of the silica hollow spheres has been presented.

  20. Operating Experience Level 3, Dangers of Respirable Silica

    Broader source: Energy.gov [DOE]

    This Operating Experience Level 3 (OE-3) document provides information on a safety concern related to recurring worker exposure to dust containing crystalline silica at Department of Energy (DOE) sites.

  1. Method of synthesizing silica nanofibers using sound waves

    DOE Patents [OSTI]

    Sharma, Jaswinder K.; Datskos, Panos G.

    2015-09-15

    A method for synthesizing silica nanofibers using sound waves is provided. The method includes providing a solution of polyvinyl pyrrolidone, adding sodium citrate and ammonium hydroxide to form a first mixture, adding a silica-based compound to the solution to form a second mixture, and sonicating the second mixture to synthesize a plurality of silica nanofibers having an average cross-sectional diameter of less than 70 nm and having a length on the order of at least several hundred microns. The method can be performed without heating or electrospinning, and instead includes less energy intensive strategies that can be scaled up to an industrial scale. The resulting nanofibers can achieve a decreased mean diameter over conventional fibers. The decreased diameter generally increases the tensile strength of the silica nanofibers, as defects and contaminations decrease with the decreasing diameter.

  2. Confinement of Metal-Organic Polyhedra in Silica Nanopores |...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Confinement of Metal-Organic Polyhedra in Silica Nanopores Previous Next List Lin-Bing Sun, Jian-Rong Li, Weigang Lu, Zhi-Yuan Gu, Zhiping Luo, and Hong-Cai Zhou, J. Am. Chem....

  3. Low-temperature geothermal assessment of the Santa Clara and Virgin River Valleys, Washington County, Utah

    SciTech Connect (OSTI)

    Budding, K.E.; Sommer, S.N.

    1986-01-01

    Exploration techniques included the following: (1) a temperature survey of springs, (2) chemical analyses and calculated geothermometer temperatures of water samples collected from selected springs and wells, (3) chemical analyses and calculated geothermometer temperatures of spring and well water samples in the literature, (4) thermal gradients measured in accessible wells, and (5) geology. The highest water temperature recorded in the St. George basin is 42/sup 0/C at Pah Tempe Hot Springs. Additional spring temperatures higher than 20/sup 0/C are at Veyo Hot Spring, Washington hot pot, and Green Spring. The warmest well water in the study area is 40/sup 0/C in Middleton Wash. Additional warm well water (higher than 24.5/sup 0/C) is present north of St. George, north of Washington, southeast of St. George, and in Dameron Valley. The majority of the Na-K-Ca calculated reservoir temperatures range between 30/sup 0/ and 50/sup 0/C. Anomalous geothermometer temperatures were calculated for water from Pah Tempe and a number of locations in St. George and vicinity. In addition to the known thermal areas of Pah Tempe and Veyo Hot Spring, an area north of Washington and St. George is delineated in this study to have possible low-temperature geothermal potential.

  4. Fluorescent single walled nanotube/silica composite materials (Patent) |

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Fluorescent single walled nanotube/silica composite materials Citation Details In-Document Search Title: Fluorescent single walled nanotube/silica composite materials Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity

  5. NEAR-IR TWO PHOTON MICROSCOPY IMAGING OF SILICA NANOPARTICLES

    Office of Scientific and Technical Information (OSTI)

    FUNCTIONALIZED WITH ISOLATED SENSITIZED Yb(III) CENTERS (Journal Article) | SciTech Connect NEAR-IR TWO PHOTON MICROSCOPY IMAGING OF SILICA NANOPARTICLES FUNCTIONALIZED WITH ISOLATED SENSITIZED Yb(III) CENTERS Citation Details In-Document Search Title: NEAR-IR TWO PHOTON MICROSCOPY IMAGING OF SILICA NANOPARTICLES FUNCTIONALIZED WITH ISOLATED SENSITIZED Yb(III) CENTERS Bright nano objects emitting in the near infrared with a maximal cross section of 41.4 x 103 GM (Goppert Mayer), were

  6. Silica diagenesis in Monterey Formation: controls and application

    SciTech Connect (OSTI)

    Kablanow, R.I. II

    1987-05-01

    The factors controlling diagenesis of biogenic silica (opal-A to opal-CT to quartz) in the Monterey Formation of California has been an ongoing subject of study. The accepted concept proposes that a high detrital content inhibits the opal-A to opal-CT reaction, whereas it accelerates the opal-CT to quartz reaction. Others have suggested that clay minerals directly influence the rate of silica transformation by the adsorption of silica from solution. It is proposed that the primary control on silica diagenesis is the thermal regime of the basin. Important variables which influence the temperature development include time, sediment accumulation rate, burial depth, porosity, thermal conductivity, temperature of silica phase change, and heat flow. The Miocene Monterey Formation had fairly rapid sedimentation rates which produced a thick section of fine-grained sediments (up to 13,000 ft, 4 km, in the Salinas basin). As these sediments underwent progressive burial, both compaction and silica transformation reduced porosity, resulting in an increase in thermal conductivity. To simulate the thermal, depositional, and diagenetic events, detailed thermal models were used. These models clearly reflect the difference in the geologic history observed between the Huasna, Pismo, and Salinas basins. The thermal models used in this study strongly confirm that silica diagenesis is primarily dependent on the temperature structure of a basin and that any catalytic influence which detrital minerals may have on silica diagenesis is a second-order effect and does not alter the regional reaction boundaries. These models can also be used as powerful tools in hydrocarbon exploration by providing a clearer picture of the thermal development of the basin.

  7. Mesoporous-silica films, fibers, and powders by evaporation

    DOE Patents [OSTI]

    Bruinsma, P.J.; Baskaran, S.; Bontha, J.R.; Liu, J.

    1999-07-13

    This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s). 24 figs.

  8. Mesoporous-silica films, fibers, and powders by evaporation

    DOE Patents [OSTI]

    Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

    2008-05-06

    This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

  9. Mesoporous-silica films, fibers, and powders by evaporation

    DOE Patents [OSTI]

    Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

    1999-01-01

    This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

  10. Addressable morphology control of silica structures by manipulating the

    Office of Scientific and Technical Information (OSTI)

    reagent addition time (Journal Article) | SciTech Connect Addressable morphology control of silica structures by manipulating the reagent addition time Citation Details In-Document Search Title: Addressable morphology control of silica structures by manipulating the reagent addition time Authors: Sharma, Jaswinder K [1] ; Datskos, Panos G [1] ; Chen, Jihua [1] + Show Author Affiliations ORNL [ORNL Publication Date: 2014-01-01 OSTI Identifier: 1110986 DOE Contract Number: DE-AC05-00OR22725

  11. Characterizing Radiation-Aged Polysiloxane-Silica Composites: Identifying

    Office of Scientific and Technical Information (OSTI)

    Changes in Network Topology via 1H NMR (Journal Article) | SciTech Connect Journal Article: Characterizing Radiation-Aged Polysiloxane-Silica Composites: Identifying Changes in Network Topology via 1H NMR Citation Details In-Document Search Title: Characterizing Radiation-Aged Polysiloxane-Silica Composites: Identifying Changes in Network Topology via 1H NMR Characterizing and quantifying changes in elastomeric materials upon exposure to harsh environments is important in the estimation of

  12. Coating thickness and coverage effects on the forces between silica

    Office of Scientific and Technical Information (OSTI)

    nanoparticles in water. (Journal Article) | SciTech Connect Coating thickness and coverage effects on the forces between silica nanoparticles in water. Citation Details In-Document Search Title: Coating thickness and coverage effects on the forces between silica nanoparticles in water. Abstract not provided. Authors: Salerno, Kenneth Michael ; Lane, J. Matthew ; Grest, Gary S. ; Ismail, Ahmed E. Publication Date: 2014-01-01 OSTI Identifier: 1140719 Report Number(s): SAND2014-0781J Journal

  13. Energy Landscape of Water and Ethanol on Silica Surfaces

    SciTech Connect (OSTI)

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-06-26

    Fundamental understanding of small molecule–silica surface interactions at their interfaces is essential for the scientific, technological, and medical communities. We report direct enthalpy of adsorption (Δhads) measurements for ethanol and water vapor on porous silica glass (CPG-10), in both hydroxylated and dehydroxylated (hydrophobic) forms. Results suggest a spectrum of energetics as a function of coverage, stepwise for ethanol but continuous for water. The zero-coverage enthalpy of adsorption for hydroxylated silica shows the most exothermic enthalpies for both water (-72.7 ± 3.1 kJ/mol water) and ethanol (-78.0 ± 1.9 kJ/mol ethanol). The water adsorption enthalpy becomes less exothermic gradually until reaching its only plateau (-20.7 ± 2.2 kJ/mol water) reflecting water clustering on a largely hydrophobic surface, while the enthalpy of ethanol adsorption profile presents two well separated plateaus, corresponding to strong chemisorption of ethanol on adsorbate-free silica surface (-66.4 ± 4.8 kJ/mol ethanol), and weak physisorption of ethanol on ethanol covered silica (-4.0 ± 1.6 kJ/mol ethanol). On the other hand, dehydroxylation leads to missing water–silica interactions, whereas the number of ethanol binding sites is not impacted. The isotherms and partial molar properties of adsorption suggest that water may only bind strongly onto the silanols (which are a minor species on silica glass), whereas ethanol can interact strongly with both silanols and the hydrophobic areas of the silica surface.

  14. Energy Landscape of Water and Ethanol on Silica Surfaces

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-06-26

    Fundamental understanding of small molecule–silica surface interactions at their interfaces is essential for the scientific, technological, and medical communities. We report direct enthalpy of adsorption (Δhads) measurements for ethanol and water vapor on porous silica glass (CPG-10), in both hydroxylated and dehydroxylated (hydrophobic) forms. Results suggest a spectrum of energetics as a function of coverage, stepwise for ethanol but continuous for water. The zero-coverage enthalpy of adsorption for hydroxylated silica shows the most exothermic enthalpies for both water (-72.7 ± 3.1 kJ/mol water) and ethanol (-78.0 ± 1.9 kJ/mol ethanol). The water adsorption enthalpy becomes less exothermic gradually until reachingmore » its only plateau (-20.7 ± 2.2 kJ/mol water) reflecting water clustering on a largely hydrophobic surface, while the enthalpy of ethanol adsorption profile presents two well separated plateaus, corresponding to strong chemisorption of ethanol on adsorbate-free silica surface (-66.4 ± 4.8 kJ/mol ethanol), and weak physisorption of ethanol on ethanol covered silica (-4.0 ± 1.6 kJ/mol ethanol). On the other hand, dehydroxylation leads to missing water–silica interactions, whereas the number of ethanol binding sites is not impacted. The isotherms and partial molar properties of adsorption suggest that water may only bind strongly onto the silanols (which are a minor species on silica glass), whereas ethanol can interact strongly with both silanols and the hydrophobic areas of the silica surface.« less

  15. Synthesis of segmented silica rods by growth temperature regulation

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect segmented silica rods by growth temperature regulation Citation Details In-Document Search Title: Synthesis of segmented silica rods by growth temperature regulation Authors: Sharma, Jaswinder K [1] ; Datskos, Panos G [1] + Show Author Affiliations ORNL Publication Date: 2014-01-01 OSTI Identifier: 1115377 DOE Contract Number: DE-AC05-00OR22725 Resource Type: Journal Article Resource Relation: Journal Name: Angewandte Chemie International Edition; Journal

  16. Synthesis of very small diameter silica nanofibers using sound waves

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect very small diameter silica nanofibers using sound waves Citation Details In-Document Search Title: Synthesis of very small diameter silica nanofibers using sound waves Authors: Sharma, Jaswinder K [1] ; Datskos, Panos G [1] ; Chen, Jihua [1] + Show Author Affiliations ORNL [ORNL Publication Date: 2014-01-01 OSTI Identifier: 1134181 DOE Contract Number: DE-AC05-00OR22725 Resource Type: Journal Article Resource Relation: Journal Name: Chemical

  17. Multifilamentation of powerful optical pulses in silica

    SciTech Connect (OSTI)

    Berge, L.; Mauger, S.; Skupin, S.

    2010-01-15

    The multiple filamentation of powerful light pulses in fused silica is numerically investigated for central wavelengths at 355 nm and 1550 nm. We consider different values for beam waist and pulse duration and compare the numerical results with behaviors expected from the plane-wave modulational instability theory. Before the nonlinear focus, the spatiotemporal intensity patterns can be explained in the framework of this theory. Once the clamping intensity is reached, for long input pulse durations (approx1 ps), the ionization front defocuses all trailing components within a collective dynamic, and a spatial replenishment scenario takes place upon further propagation. Short pulses (approx50 fs) undergo similar ionization fronts, before an optically turbulent regime sets in. We observe moderate changes in the total temporal extent of ultraviolet pulses and in the corresponding spectra. In contrast, infrared pulses may undergo strong temporal compression and important spectral broadening. For short input pulses, anomalous dispersion and self-steepening push all pulse components to the trailing edge, where many small-scaled filaments are nucleated. In the leading part of the pulse, different spatial landscapes, e.g., broad ring patterns, may survive and follow their own propagation dynamics.

  18. Silica recovery and control in Hawaiian geothermal fluids. Final report

    SciTech Connect (OSTI)

    Thomas, D.M.

    1992-06-01

    A series of experiments was performed to investigate methods of controlling silica in waste geothermal brines produced at the HGP-A Generator Facility. Laboratory testing has shown that the rate of polymerization of silica in the geothermal fluids is highly pH dependent. At brine pH values in excess of 8.5 the suspension of silica polymers flocculated and rapidly precipitated a gelatinous silica mass. Optimum flocculation and precipitation rates were achieved at pH values in the range of 10.5 to 11.5. The addition of transition metal salts to the geothermal fluids similarly increased the rate of polymerization as well as the degree of precipitation of the silica polymer from suspension. A series of experiments performed on the recovered silica solids demonstrated that methanol extraction of the water in the gels followed by critical point drying yielded surface areas in excess of 300 M{sup 2}/g and that treatment of the dried solids with 2 N HCl removed most of the adsorbed impurities in the recovered product. A series of experiments tested the response of the waste brines to mixing with steam condensate and non-condensable gases.The results demonstrated that the addition of condensate and NCG greatly increased the stability of the silica in the geothermal brines. They also indicated that the process could reduce the potential for plugging of reinjection wells receiving waste geothermal fluids from commercial geothermal facilities in Hawaii. Conceptual designs were proposed to apply the gas re-combination approach to the disposal of geothermal waste fluids having a range of chemical compositions. Finally, these designs were applied to the geothermal fluid compositions found at Cerro Prieto, Ahuachapan, and Salton Sea.

  19. Silica recovery and control in Hawaiian geothermal fluids

    SciTech Connect (OSTI)

    Thomas, D.M.

    1992-06-01

    A series of experiments was performed to investigate methods of controlling silica in waste geothermal brines produced at the HGP-A Generator Facility. Laboratory testing has shown that the rate of polymerization of silica in the geothermal fluids is highly pH dependent. At brine pH values in excess of 8.5 the suspension of silica polymers flocculated and rapidly precipitated a gelatinous silica mass. Optimum flocculation and precipitation rates were achieved at pH values in the range of 10.5 to 11.5. The addition of transition metal salts to the geothermal fluids similarly increased the rate of polymerization as well as the degree of precipitation of the silica polymer from suspension. A series of experiments performed on the recovered silica solids demonstrated that methanol extraction of the water in the gels followed by critical point drying yielded surface areas in excess of 300 M{sup 2}/g and that treatment of the dried solids with 2 N HCl removed most of the adsorbed impurities in the recovered product. A series of experiments tested the response of the waste brines to mixing with steam condensate and non-condensable gases.The results demonstrated that the addition of condensate and NCG greatly increased the stability of the silica in the geothermal brines. They also indicated that the process could reduce the potential for plugging of reinjection wells receiving waste geothermal fluids from commercial geothermal facilities in Hawaii. Conceptual designs were proposed to apply the gas re-combination approach to the disposal of geothermal waste fluids having a range of chemical compositions. Finally, these designs were applied to the geothermal fluid compositions found at Cerro Prieto, Ahuachapan, and Salton Sea.

  20. Functionalized mesoporous silica nanoparticles for oral delivery of budesonide

    SciTech Connect (OSTI)

    Yoncheva, K.; Popova, M.; Szegedi, A.; Mihaly, J.; Tzankov, B.; Lambov, N.; Konstantinov, S.; Tzankova, V.; Pessina, F.; Valoti, M.

    2014-03-15

    Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of the nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide. -- Graphical abstract: Silica mesoporous MCM-41 particles were amino-functionalized, loaded with budesonide and post-coated with bioadhesive polymer (carbopol) in order to achieve prolonged residence of anti-inflammatory drug in GIT. Highlights: Higher drug loading in amino-functionalized mesoporous silica. Amino-functionalization and post-coating of the nanoparticles sustained drug release. Achievement of higher cytoprotective effect with drug loaded into the nanoparticles.

  1. Temperature and moisture dependence of dielectric constant for silica aerogels

    SciTech Connect (OSTI)

    Hrubesh, L.H., LLNL

    1997-03-01

    The dielectric constants of silica aerogels are among the lowest measured for any solid material. The silica aerogels also exhibit low thermal expansion and are thermally stable to temperatures exceeding 500{degrees}C. However, due to the open porosity and large surface areas for aerogels, their dielectric constants are strongly affected by moisture and temperature. This paper presents data for the dielectric constants of silica aerogels as a function of moisture content at 25{degrees}C, and as a function of temperature, for temperatures in the range from 25{degrees}C to 450{degrees}C. Dielectric constant data are also given for silica aerogels that are heat treated in dry nitrogen at 500{degrees}C, then cooled to 25{degrees}C for measurements in dry air. All measurements are made on bulk aerogel spheres at 22GHz microwave frequency, using a cavity perturbation method. The results of the dependence found here for bulk materials can be inferred to apply also to thin films of silica aerogels having similar nano-structures and densities.

  2. Surface modification of low density silica and bridged polysilsesquioxane aerogels

    SciTech Connect (OSTI)

    DeFriend, K. A. (Kimberly A.); Loy, D. A. (Douglas A.); Salazar, K. V. (Kenneth V.); Wilson, K. V. (Kennard V.)

    2004-01-01

    Silica and bridged polysilsesquioxane aerogels are low density materials that are attractive for applications such as, thermal insulation, porous separation media or catalyst supports, adsorbents. However, aerogels are notoriously weak and brittle making it difficult to handle and machine monoliths into desired forms. This prevents the development of many applications that would otherwise benefit from the use of the low density materials. We will describe our efforts to chemically modify and mechanically enhance silica-based aerogels using chemical vapor techniques without sacrificing their characteristic low densities. Monolithic silica and organically bridged polysilsesquioxane aerogels were prepared by sol-gel polymerization of the respective methoxysilane monomers followed by supercritical carbon dioxide drying of the gels. Reactive modification of the gels with volatile silylating compounds during and after the drying process and these effects on the mechanical properties and density of the aerogels will be described.

  3. PATCHY SILICA-COATED SILVER NANOWIRES AS SERS SUBSTRATES

    SciTech Connect (OSTI)

    Murph, S.; Murphy, C.

    2013-03-29

    We report a class of core-shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4- mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified Stber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV-visible spectroscopy and phase-analysis light scattering for measuring effective surface charge. Surprisingly, the patchy silica coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, nano-matryoshka configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (hot spots) in the Raman scattering experiment.

  4. Luminescent single-walled carbon nanotube/silica composite materials

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Luminescent single-walled carbon nanotube/silica composite materials Citation Details In-Document Search Title: Luminescent single-walled carbon nanotube/silica composite materials Authors: Dattelbaum, Andrew M [1] + Show Author Affiliations Los Alamos National Laboratory Publication Date: 2011-06-10 OSTI Identifier: 1072338 Report Number(s): LA-UR-11-03375; LA-UR-11-3375 DOE Contract Number: AC52-06NA25396 Resource Type: Conference Resource Relation:

  5. Increasing Class C fly ash reduces alkali silica reactivity

    SciTech Connect (OSTI)

    Hicks, J.K.

    2007-07-01

    Contrary to earlier studies, it has been found that incremental additions of Class C fly ash do reduce alkali silica reactivity (ASR), in highly reactive, high alkali concrete mixes. AST can be further reduced by substituting 5% metakaolin or silica fume for the aggregate in concrete mixes with high (more than 30%) Class C fly ash substitution. The paper reports results of studies using Class C fly ash from the Labadie Station plant in Missouri which typically has between 1.3 and 1.45% available alkalis by ASTM C311. 7 figs.

  6. Method for dissolution and stabilization of silica-rich fibers

    DOE Patents [OSTI]

    Jantzen, Carol M.

    1997-01-01

    A method for dissolving silica-rich fibers such as borosilicate fibers, fiberglass and asbestos to stabilize them for disposal. The method comprises (1) immersing the fibers in hot, five-weight-percent sodium hydroxide solution until the concentration of dissolved silica reaches equilibrium and a only a residue is left (about 48 hours), then immersing the residue in hot, five-weight-percent nitric acid until the residue dissolves (about 96 hours). After adjusting the pH of the dissolved fibers to be caustic, the solution can then be added to a waste vitrification stream for safe disposal. The method is useful in disposing contaminated HEME and HEPA filters.

  7. Low-Cost, Haziness-Free, Transparent Insulation Based On a Porous Silica

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Material | Department of Energy Low-Cost, Haziness-Free, Transparent Insulation Based On a Porous Silica Material Low-Cost, Haziness-Free, Transparent Insulation Based On a Porous Silica Material Image of porous silica material in alcohol.<br /> Photo credit: Oak Ridge National Lab Image of porous silica material in alcohol. Photo credit: Oak Ridge National Lab Lead Performer: Oak Ridge National Laboratory - Oak Ridge, TN Partner: VELUX Design and Development Company USA Inc.,

  8. Evaluation of low-temperature geothermal potential in Cache Valley, Utah. Report of investigation No. 174

    SciTech Connect (OSTI)

    de Vries, J.L.

    1982-11-01

    Field work consisted of locating 90 wells and springs throughout the study area, collecting water samples for later laboratory analyses, and field measurement of pH, temperature, bicarbonate alkalinity, and electrical conductivity. Na/sup +/, K/sup +/, Ca/sup +2/, Mg/sup +2/, SiO/sub 2/, Fe, SO/sub 4//sup -2/, Cl/sup -/, F/sup -/, and total dissolved solids were determined in the laboratory. Temperature profiles were measured in 12 additional, unused walls. Thermal gradients calculated from the profiles were approximately the same as the average for the Basin and Range province, about 35/sup 0/C/km. One well produced a gradient of 297/sup 0/C/km, most probably as a result of a near-surface occurrence of warm water. Possible warm water reservoir temperatures were calculated using both the silica and the Na-K-Ca geothermometers, with the results averaging about 50 to 100/sup 0/C. If mixing calculations were applied, taking into account the temperatures and silica contents of both warm springs or wells and the cold groundwater, reservoir temperatures up to about 200/sup 0/C were indicated. Considering measured surface water temperatures, calculated reservoir temperatures, thermal gradients, and the local geology, most of the Cache Valley, Utah area is unsuited for geothermal development. However, the areas of North Logan, Benson, and Trenton were found to have anomalously warm groundwater in comparison to the background temperature of 13.0/sup 0/C for the study area. The warm water has potential for isolated energy development but is not warm enough for major commercial development.

  9. High temperature thermographic measurements of laser heated silica

    SciTech Connect (OSTI)

    Elhadj, S; Yang, S T; Matthews, M J; Cooke, D J; Bude, J D; Johnson, M; Feit, M; Draggoo, V; Bisson, S E

    2009-11-02

    In situ spatial and temporal surface temperature profiles of CO{sub 2} laser-heated silica were obtained using a long wave infrared (LWIR) HgCdTe camera. Solutions to the linear diffusion equation with volumetric and surface heating are shown to describe the temperature evolution for a range of beam powers, over which the peak surface temperature scales linearly with power. These solutions were used with on-axis steady state and transient experimental temperatures to extract thermal diffusivity and conductivity for a variety of materials, including silica, spinel, sapphire, and lithium fluoride. Experimentally-derived thermal properties agreed well with reported values and, for silica, thermal conductivity and diffusivity are shown to be approximately independent of temperature between 300 and 2800K. While for silica our analysis based on a temperature independent thermal conductivity is shown to be accurate, for other materials studied this treatment yields effective thermal properties that represent reasonable approximations for laser heating. Implementation of a single-wavelength radiation measurement in the semi-transparent regime is generally discussed, and estimates of the apparent temperature deviation from the actual outer surface temperature are also presented. The experimental approach and the simple analysis presented yield surface temperature measurements that can be used to validate more complex physical models, help discriminate dominant heat transport mechanisms, and to predict temperature distribution and evolution during laser-based material processing.

  10. Fractal Studies on Titanium-Silica Aerogels using SMARTer

    SciTech Connect (OSTI)

    Putra, E. Giri Rachman; Ikram, A.; Bharoto; Santoso, E. [Neutron Scattering Laboratory, BATAN, Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia); Fang, T. Chiar; Ibrahim, N. [Department of Physics, Faculty of Science Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor (Malaysia); Mohamed, A. Aziz [Materials Technology Group, Industrial Technology Division Agensi Nuklear Malaysia, 43000 Kajang (Malaysia)

    2008-03-17

    Power-law scattering approximation has been employed to reveal the fractal structures of solid-state titanium-silica aerogel samples. All small-angle neutron scattering (SANS) measurements were performed using 36 meters SANS BATAN spectrometer (SMARTer) at the neutron scattering laboratory (NSL) in Serpong, Indonesia. The mass fractal dimension of titanium-silica aerogels at low scattering vector q range increases from -1.4 to -1.92 with the decrease of acid concentrations during sol-gel process. These results are attributed to the titanium-silica aerogels that are growing to more polymeric and branched structures. At high scattering vector q range the Porod slope of -3.9 significantly down to -2.24 as the roughness of particle surfaces becomes higher. The cross over between these two regimes decreases from 0.4 to 0.16 nm{sup -1} with the increase of acid concentrations indicating also that the titanium-silica aerogels are growing.

  11. Silica-Supported Tantalum Clusters: Catalyst for Alkane Conversion

    SciTech Connect (OSTI)

    Nemana ,S.; Gates, B.

    2006-01-01

    Silica-supported tantalum clusters (on average, approximately tritantalum) were formed by the treatment, in either H{sub 2} or ethane, of adsorbed Ta(CH{sub 2}Ph){sub 5}; the supported catalyst is active for ethane conversion to methane and propane at 523 K, with the used catalyst containing clusters of the same average nuclearity as the precursor.

  12. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    SciTech Connect (OSTI)

    Munaweera, Imalka; Balkus, Kenneth J. Jr. E-mail: Anthony.DiPasqua@unthsc.edu; Koneru, Bhuvaneswari; Shi, Yi; Di Pasqua, Anthony J. E-mail: Anthony.DiPasqua@unthsc.edu

    2014-11-01

    Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, {sup 1}H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  13. Molecular engineering of porous silica using aryl templates

    DOE Patents [OSTI]

    Loy, Douglas A.; Shea, Kenneth J.

    1994-01-01

    A process for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular seives, dessicants, and catalyst supports are produced.

  14. Molecular engineering of porous silica using aryl templates

    DOE Patents [OSTI]

    Loy, D.A.; Shea, K.J.

    1994-06-14

    A process is described for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular sieves, desiccants, and catalyst supports are produced. 3 figs.

  15. Silica aerogels modified by functional and nonfunctional organic groups

    SciTech Connect (OSTI)

    Schubert, U.; Huesing, N.; Schwertfeger, F. [Universitaet Wien (Austria)

    1996-12-31

    Organically substituted silica aerogels were prepared from RSi(OR`){sub 3}/Si(OR`){sub 4} mixtures, followed by supercritical drying. The typical microstructure and the resulting physical properties of silica aerogels are retained, if the portion of R-Si units is below 10-20%. However, new properties are supplemented, such as hydrophobicity (which makes the aerogels insensitive towards moisture), a higher compliance, and the possibility to incorporate functional organic groups. Controlled pyrolysis of the organically substituted aerogels allows to coat the inner surface of the aerogels with nanometer-sized carbon structures. This results in a very efficient infrared opacification and improved heat insulation properties at high temperatures. 5 refs., 2 figs.

  16. Method for dissolution and stabilization of silica-rich fibers

    DOE Patents [OSTI]

    Jantzen, C.M.

    1997-11-11

    A method is described for dissolving silica-rich fibers such as borosilicate fibers, fiberglass and asbestos to stabilize them for disposal. The method comprises (1) immersing the fibers in hot, five-weight-percent sodium hydroxide solution until the concentration of dissolved silica reaches equilibrium and a only a residue is left (about 48 hours), then immersing the residue in hot, five-weight-percent nitric acid until the residue dissolves (about 96 hours). After adjusting the pH of the dissolved fibers to be caustic, the solution can then be added to a waste vitrification stream for safe disposal. The method is useful in disposing contaminated HEME and HEPA filters. 1 fig.

  17. Synthesis of mesoporous silica materials from municipal solid waste incinerator bottom ash

    SciTech Connect (OSTI)

    Liu, Zhen-Shu Li, Wen-Kai; Huang, Chun-Yi

    2014-05-01

    Highlights: The optimal alkaline agent for the extraction of silica from bottom ash was Na{sub 2}CO{sub 3}. The pore sizes for the mesoporous silica synthesized from bottom ash were 23.8 nm. The synthesized materials exhibited a hexagonal pore structure with a smaller order. The materials have potential for the removal of heavy metals from aqueous solutions. - Abstract: Incinerator bottom ash contains a large amount of silica and can hence be used as a silica source for the synthesis of mesoporous silica materials. In this study, the conditions for alkaline fusion to extract silica from incinerator bottom ash were investigated, and the resulting supernatant solution was used as the silica source for synthesizing mesoporous silica materials. The physical and chemical characteristics of the mesoporous silica materials were analyzed using BET, XRD, FTIR, SEM, and solid-state NMR. The results indicated that the BET surface area and pore size distribution of the synthesized silica materials were 992 m{sup 2}/g and 23.8 nm, respectively. The XRD patterns showed that the synthesized materials exhibited a hexagonal pore structure with a smaller order. The NMR spectra of the synthesized materials exhibited three peaks, corresponding to Q{sup 2} [Si(OSi){sub 2}(OH){sub 2}], Q{sup 3} [Si(OSi){sub 3}(OH)], and Q{sup 4} [Si(OSi){sub 4}]. The FTIR spectra confirmed the existence of a surface hydroxyl group and the occurrence of symmetric SiO stretching. Thus, mesoporous silica was successfully synthesized from incinerator bottom ash. Finally, the effectiveness of the synthesized silica in removing heavy metals (Pb{sup 2+}, Cu{sup 2+}, Cd{sup 2+}, and Cr{sup 2+}) from aqueous solutions was also determined. The results showed that the silica materials synthesized from incinerator bottom ash have potential for use as an adsorbent for the removal of heavy metals from aqueous solutions.

  18. Silica diagenesis in Santa Cruz mudstone, Late Miocene, California

    SciTech Connect (OSTI)

    El-Sabbagh, D.

    1987-05-01

    The silica-rich upper Miocene Santa Cruz Mudstone is similar to the Miocene Monterey Formation. Previous studies have suggested the Santa Cruz Mudstone was not buried deeply nor had it undergone extensive diagenesis. Because opaline diagenesis is temperature dependent, the author examined the silica diagenesis of the Santa Cruz Mudstone using scanning electron microscopy and x-ray diffraction methods to study its burial history. In a series of samples from Santa Cruz to Davenport, California (over 16 km), opal-CT is the dominant silica phase present and clay minerals are notably absent. The d(101)-spacing values of opal-CT range from 4.11 A (Santa Cruz area) to 4.06 A (north of Santa Cruz), exhibiting the complete range of d(101)-spacing values found in opal-CT zones. Scanning electron micrographs of crystalline microtextures show rosettes of opal-CT (lepispheres) in cavities of samples with medium to high d(101)-spacing values. The morphology of lepisphere crystallites grades from bladed to spiny with decreasing d(101)-spacing values, reflecting an internal crystal ordering with increased diagenesis. Further diagenetic changes occurred in a sample with 4.06 A d(101)-spacing where incipient quartz crystals signal the initial conversion of opal-CT to microcrystalline quartz. Silica diagenesis demonstrates that burial temperatures surpassed the range of opal-A to opal-CT conversion and approached conversion temperatures (55/sup 0/C to 110/sup 0/C) of opal-CT to microcrystalline quartz. The conversion occurred when the Santa Cruz Mudstone was buried over 1900 m (depth calculated from a geohistory diagram). This burial temperature brings the Santa Cruz Mudstone within the oil generation window, and could account for the presence of hydrocarbons in the unit.

  19. Hollow microspheres of silica glass and method of manufacture

    DOE Patents [OSTI]

    Downs, Raymond L.; Miller, Wayne J.

    1982-01-01

    A method of manufacturing gel powder suitable for use as a starting material in the manufacture of hollow glass microspheres having a high concentration of silica. The powder is manufactured from a gel containing boron in the amount of about 1% to 20% (oxide equivalent mole percent), alkali metals, specifically potassium and sodium, in an amount exceeding 8% total, and the remainder silicon. Preferably, the ratio of potassium to sodium is greater than 1.5.

  20. Process for manufacturing hollow fused-silica insulator cylinder

    DOE Patents [OSTI]

    Sampayan, Stephen E.; Krogh, Michael L.; Davis, Steven C.; Decker, Derek E.; Rosenblum, Ben Z.; Sanders, David M.; Elizondo-Decanini, Juan M.

    2001-01-01

    A method for building hollow insulator cylinders that can have each end closed off with a high voltage electrode to contain a vacuum. A series of fused-silica round flat plates are fabricated with a large central hole and equal inside and outside diameters. The thickness of each is related to the electron orbit diameter of electrons that escape the material surface, loop, and return back. Electrons in such electron orbits can support avalanche mechanisms that result in surface flashover. For example, the thickness of each of the fused-silica round flat plates is about 0.5 millimeter. In general, the thinner the better. Metal, such as gold, is deposited onto each top and bottom surface of the fused-silica round flat plates using chemical vapor deposition (CVD). Eutectic metals can also be used with one alloy constituent on the top and the other on the bottom. The CVD, or a separate diffusion step, can be used to defuse the deposited metal deep into each fused-silica round flat plate. The conductive layer may also be applied by ion implantation or gas diffusion into the surface. The resulting structure may then be fused together into an insulator stack. The coated plates are aligned and then stacked, head-to-toe. Such stack is heated and pressed together enough to cause the metal interfaces to fuse, e.g., by welding, brazing or eutectic bonding. Such fusing is preferably complete enough to maintain a vacuum within the inner core of the assembled structure. A hollow cylinder structure results that can be used as a core liner in a dielectric wall accelerator and as a vacuum envelope for a vacuum tube device where the voltage gradients exceed 150 kV/cm.

  1. Silica aerogel: An intrinsically low dielectric constant material

    SciTech Connect (OSTI)

    Hrubesh, L.W.

    1995-04-01

    Silica aerogels are highly porous solids having unique morphologies in wavelength of visible which both the pores and particles have sizes less than the wavelength of visible light. This fine nanostructure modifies the normal transport mechanisms within aerogels and endows them with a variety of exceptional physical properties. For example, aerogels have the lowest measured thermal conductivity and dielectric constant for any solid material. The intrinsically low dielectric properties of silica aerogels are the direct result of the extremely high achievable porosities, which are controllable over a range from 75% to more than 99.8 %, and which result in measured dielectric constants from 2.0 to less than 1.01. This paper discusses the synthesis of silica aerogels, processing them as thin films, and characterizing their dielectric properties. Existing data and other physical characteristics of bulk aerogels (e.g., thermal stablity, thermal expansion, moisture adsorption, modulus, dielectric strength, etc.), which are useful for evaluating them as potential dielectrics for microelectronics, are also given.

  2. Silylation of low-density silica and bridged polysilsesquioxane aerogels

    SciTech Connect (OSTI)

    DeFriend, K. A. (Kimberly A.); Loy, D. A. (Douglas A.); Salazar, K. V. (Kenneth V.); Wilson, K. V. (Kennard V.)

    2004-01-01

    Silica and bridged polysilsesquioxane aerogels are low-density materials that are attractive for applications such as thermal insulation, porous separation media or catalyst supports, adsorbents, and cometary dust capture agents. However, aerogels are notoriously weak and brittle making it difficult to handle and machine monoliths into desired forms. This complication prevents the development of many applications that would otherwise benefit from the use of the low-density materials. Here, we will describe our efforts to chemically modify and mechanically enhance silica-based aerogels using chemical vapor techniques without sacrificing their characteristic low densities. Monolithic silica and organic-bridged polysilsesquioxane aerogels were prepared by sol-gel polymerization of the respective methoxysilane monomers followed by supercritical carbon dioxide drying of the gels. Then the gels were reactively modified with silylating agents to demonstrate the viability of CVD modification of aerogels, and to determine the effects of silylation of surface silanols on the morphology, surface area, and mechanical properties of the resulting aerogels.

  3. Optical emission from erbium-doped silica nanowires

    SciTech Connect (OSTI)

    Elliman, R. G.; Wilkinson, A. R.; Kim, T.-H.; Sekhar, P. K.; Bhansali, S.

    2008-05-15

    Infrared optical emission from erbium-doped silica nanowires is shown to have property characteristic of the material nanostructure and to provide the basis for the fabrication of integrated photonic devices and biosensors. Silica nanowires of approximately 150 nm diameter were grown on a silicon wafer by metal-induced growth using a thin (20 nm) sputter-deposited palladium layer as a catalyst. The resulting wires were then ion implanted with 110 keV ErO{sup -} ions and annealed at 900 deg. C to optically activate the erbium. These wires exhibited photoluminescence emission at 1.54 {mu}m, characteristic of the {sup 4}I{sub 15/2}-{sup 4}I{sub 13/2} transition in erbium; however, comparison to similarly implanted fused silica layers revealed stronger thermal quenching and longer luminescence lifetimes in the nanowire samples. The former is attributed to an increase in defect-induced quenching partly due to the large surface-volume ratio of the nanowires, while the latter is attributed to a reduction in the optical density of states associated with the nanostructure morphology. Details of this behavior are discussed together with the implications for potential device applications.

  4. Antireflective graded index silica coating, method for making

    DOE Patents [OSTI]

    Yoldas, Bulent E.; Partlow, Deborah P.

    1985-01-01

    Antireflective silica coating for vitreous material is substantially non-reflecting over a wide band of radiations. This is achieved by providing the coating with a graded degree of porosity which grades the index of refraction between that of air and the vitreous material of the substrate. To prepare the coating, there is first prepared a silicon-alkoxide-based coating solution of particular polymer structure produced by a controlled proportion of water to alkoxide and a controlled concentration of alkoxide to solution, along with a small amount of catalyst. The primary solvent is alcohol and the solution is polymerized and hydrolized under controlled conditions prior to use. The prepared solution is applied as a film to the vitreous substrate and rapidly dried. It is thereafter heated under controlled conditions to volatilize the hydroxyl radicals and organics therefrom and then to produce a suitable pore morphology in the residual porous silica layer. The silica layer is then etched in order to enlarge the pores in a graded fashion, with the largest of the pores remaining being sufficiently small that radiations to be passed through the substrate are not significantly scattered. For use with quartz substrates, extremely durable coatings which display only 0.1% reflectivity have been prepared.

  5. Synthesis of silica coated zinc oxide-poly(ethylene-co-acrylic acid)

    Office of Scientific and Technical Information (OSTI)

    matrix and its UV shielding evaluation (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Synthesis of silica coated zinc oxide-poly(ethylene-co-acrylic acid) matrix and its UV shielding evaluation Citation Details In-Document Search Title: Synthesis of silica coated zinc oxide-poly(ethylene-co-acrylic acid) matrix and its UV shielding evaluation Graphical abstract: - Highlights: * Well layer thickness controlled silica shell was made on ZnO nanoparticles. *

  6. Preparation of silica stabilized biological templates for the production of metal and layered nanoparticles

    DOE Patents [OSTI]

    Culver, James N; Royston, Elizabeth; Brown, Adam; Harris, Michael

    2013-02-26

    The present invention relates to a system and method providing for increased silica growth on a bio-template, wherein the bio-template is pretreated with aniline to produce a uniform silica attractive surface and yielding a significant silica layers of at least 10 nm, and more preferably at least 20 nm in thickness, thereby providing for a high degree of stability to the bio-template.

  7. Oxidative alteration of spent fuel in a silica-rich environment...

    Office of Scientific and Technical Information (OSTI)

    SEMAEM investigation and geochemical modeling Citation Details In-Document Search Title: Oxidative alteration of spent fuel in a silica-rich environment: SEMAEM ...

  8. Synthesis and new structure shaping mechanism of silica particles formed at high pH

    SciTech Connect (OSTI)

    Zhang, Henan; Zhao, Yu; Akins, Daniel L.

    2012-10-15

    For the sol-gel synthesis of silica particles under high pH catalytic conditions (pH>12) in water/ethanol solvent, we have deduced that the competing dynamics of chemical etching and sol-gel process can explain the types of silica particles formed and their morphologies. We have demonstrated that emulsion droplets that are generated by adding tetraethyl orthosilicate (TEOS) to a water-ethanol solution serve as soft templates for hollow spherical silica (1-2 {mu}m). And if the emulsion is converted by the sol-gel process, one finds that suspended solid silica spheres of diameter of {approx}900 nm are formed. Moreover, several other factors are found to play fundamental roles in determining the final morphologies of silica particles, such as by variation of the pH (in our case, using OH{sup -}) to a level where condensation dominates; by changing the volume ratios of water/ethanol; and using an emulsifier (specifically, CTAB) - Graphical abstract: 'Local chemical etching' and sol-gel process have been proposed to interpret the control of morphologies of silica particles through varying initial pHs in syntheses. Highlights: Black-Right-Pointing-Pointer Different initial pHs in our syntheses provides morphological control of silica particles. Black-Right-Pointing-Pointer 'Local chemical etching' and sol-gel process describes the formation of silica spheres. Black-Right-Pointing-Pointer The formation of emulsions generates hollow silica particles.

  9. Characterization of Dry-Air Aged Granules of Silver-Functionalized Silica

    Office of Scientific and Technical Information (OSTI)

    Aerogel (Technical Report) | SciTech Connect Dry-Air Aged Granules of Silver-Functionalized Silica Aerogel Citation Details In-Document Search Title: Characterization of Dry-Air Aged Granules of Silver-Functionalized Silica Aerogel This is a letter report to complete level 3 milestone "Assess aging characteristics of silica aerogels" for DOE FCRD program. Recently, samples of Ag0-functionalized silica aerogel were aged in flowing dry air for up to 6 months and then loaded with

  10. Confinement of Metal-Organic Polyhedra in Silica Nanopores | Center for

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Gas SeparationsRelevant to Clean Energy Technologies | Blandine Jerome Confinement of Metal-Organic Polyhedra in Silica Nanopores

  11. Thermal annealing of laser damage precursors on fused silica surfaces

    SciTech Connect (OSTI)

    Shen, N; Miller, P E; Bude, J D; Laurence, T A; Suratwala, T I; Steele, W A; Feit, M D; Wang, L L

    2012-03-19

    Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences <8 J/cm{sup 2} could be improved >35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.

  12. Favorable Geochemistry from Springs and Wells in COlorado

    SciTech Connect (OSTI)

    Zehner, Richard E.

    2012-02-01

    Citation Information: Originator: Geothermal Development Associates, Reno Nevada Originator: United States Geological Survey (USGS) Originator: Colorado Geological Survey Publication Date: 2012 Title: Favorable Geochemistry Edition: First Publication Information: Publication Place: Reno Nevada Publisher: Geothermal Development Associates, Reno, Nevada Description: This layer contains favorable geochemistry for high-temperature geothermal systems, as interpreted by Richard "Rick" Zehner. The data is compiled from the data obtained from the USGS. The original data set combines 15,622 samples collected in the State of Colorado from several sources including 1) the original Geotherm geochemical database, 2) USGS NWIS (National Water Information System), 3) Colorado Geological Survey geothermal sample data, and 4) original samples collected by R. Zehner at various sites during the 2011 field season. These samples are also available in a separate shapefile FlintWaterSamples.shp. Data from all samples were reportedly collected using standard water sampling protocols (filtering through 0.45 micron filter, etc.) Sample information was standardized to ppm (micrograms/liter) in spreadsheet columns. Commonly-used cation and silica geothermometer temperature estimates are included. Spatial Domain: Extent: Top: 4515595.841032 m Left: 149699.513964 m Right: 757959.309388 m Bottom: 4104156.435530 m Contact Information: Contact Organization: Geothermal Development Associates, Reno, Nevada Contact Person: Richard “Rick” Zehner Address: 3740 Barron Way City: Reno State: NV Postal Code: 89511 Country: USA Contact Telephone: 775-737-7806 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System 1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  13. Some engineering properties of heavy concrete added silica fume

    SciTech Connect (OSTI)

    Akka?, Ay?e; Ba?yi?it, Celalettin; Esen, Serap

    2013-12-16

    Many different types of building materials have been used in building construction for years. Heavy concretes can be used as a building material for critical building as it can contain a mixture of many heavy elements. The barite itself for radiation shielding can be used and also in concrete to produce the workable concrete with a maximum density and adequate structural strength. In this study, some engineering properties like compressive strength, elasticity modules and flexure strength of heavy concretes added Silica fume have been investigated.

  14. Patterning of silica microsphere monolayers with focused femtosecond laser pulses

    SciTech Connect (OSTI)

    Cai Wenjian; Piestun, Rafael

    2006-03-13

    We demonstrate the patterning of monolayer silica microsphere lattices with tightly focused femtosecond laser pulses. We selectively removed microspheres from a lattice and characterized the effect on the lattice and the substrate. The proposed physical mechanism for the patterning process is laser-induced breakdown followed by ablation of material. We show that a microsphere focuses radiation in its interior and in the near field. This effect plays an important role in the patterning process by enhancing resolution and accuracy and by reducing the pulse energy threshold for damage. Microsphere patterning could create controlled defects within self-assembled opal photonic crystals.

  15. Controlled release of ibuprofen by mesomacroporous silica

    SciTech Connect (OSTI)

    Santamara, E. Maestro, A.; Porras, M.; Gutirrez, J.M.; Gonzlez, C.

    2014-02-15

    Structured mesomacroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)poly(propylene oxide)poly(ethylene oxide) (EO{sub 19}PO{sub 39}EO{sub 19}) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorptiondesorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered mesomacroporous materials. The effect of the materials properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system. - Graphical abstract: Ibuprofen release profiles for the materials obtained from samples P84{sub m}eso (black diamonds), P84{sub 2}0% (white squares), P84{sub 5}0% (black triangles), P84{sub 7}5% (white diamonds), P84{sub 7}5% functionalized by grafting (black squares) and P84{sub 7}5% functionalized by co-condensation method (white triangles). Display Omitted - Highlights: Ordered mesomacroporous material is used as a controlled delivery system for ibuprofen. Incorporation of macropores in mesoporous silica improves ibuprofen adsorption. Mesomacroporous structures provide a lower delivery than mesoporous silica. APTES functionalization in mesomacroporous materials improves ibuprofen adsorption and delivery behaviour.

  16. Chemical treatment for silica-containing glass surfaces

    DOE Patents [OSTI]

    Grabbe, Alexis; Michalske, Terry Arthur; Smith, William Larry

    1999-01-01

    Dehydroxylated, silica-containing, glass surfaces are known to be at least partially terminated by strained siloxane rings. According to the invention, a surface of this kind is exposed to a selected silane compound or mixture of silane compounds under reaction-promoting conditions. The ensuing reaction results in opening of the strained siloxane rings, and termination of surface atoms by chemical species, such as organic or organosilicon species, having desirable properties. These species can be chosen to provide qualities such as hydrophobicity, or improved coupling to a polymeric coating.

  17. Chemical treatment for silica-containing glass surfaces

    DOE Patents [OSTI]

    Grabbe, Alexis; Michalske, Terry Arthur; Smith, William Larry

    1999-01-01

    Dehydroxylated, silica-containing, glass surfaces are known to be at least partially terminated by strained siloxane rings. According to the invention, a surface of this kind is exposed to a selected silane compound or mixture of silane compounds under reaction-promoting conditons. The ensuing reaction results in opening of the strained siloxane rings, and termination of surface atoms by chemical species, such as organic or organosilicon species, having desirable properties. These species can be chosen to provide qualities such as hydrophobicity, or improved coupling to a polymeric coating.

  18. Method for chemical surface modification of fumed silica particles

    DOE Patents [OSTI]

    Grabbe, Alexis; Michalske, Terry Arthur; Smith, William Larry

    1999-01-01

    Dehydroxylated, silica-containing, glass surfaces are known to be at least partially terminated by strained siloxane rings. According to the invention, a surface of this kind is exposed to a selected silane compound or mixture of silane compounds under reaction-promoting conditions. The ensuing reaction results in opening of the strained siloxane rings, and termination of surface atoms by chemical species, such as organic or organosilicon species, having desirable properties. These species can be chosen to provide qualities such as hydrophobicity, or improved coupling to a polymeric coating.

  19. Chemical treatment for silica-containing glass surfaces

    DOE Patents [OSTI]

    Grabbe, Alexis; Michalske, Terry Arthur; Smith, William Larry

    1998-01-01

    Dehydroxylated, silica-containing, glass surfaces are known to be at least partially terminated by strained siloxane rings. According to the invention, a surface of this kind is exposed to a selected silane compound or mixture of silane compounds under reaction-promoting conditions. The ensuing reaction results in opening of the strained siloxane rings, and termination of surface atoms by chemical species, such as organic or organosilicon species, having desirable properties. These species can be chosen to provide qualities such as hydrophobicity, or improved coupling to a polymeric coating.

  20. Chemical treatment for silica-containing glass surfaces

    DOE Patents [OSTI]

    Grabbe, A.; Michalske, T.A.; Smith, W.L.

    1998-04-07

    Dehydroxylated, silica-containing, glass surfaces are known to be at least partially terminated by strained siloxane rings. According to the invention, a surface of this kind is exposed to a selected silane compound or mixture of silane compounds under reaction-promoting conditions. The ensuing reaction results in opening of the strained siloxane rings, and termination of surface atoms by chemical species, such as organic or organosilicon species, having desirable properties. These species can be chosen to provide qualities such as hydrophobicity, or improved coupling to a polymeric coating. 11 figs.

  1. Method for chemical surface modification of fumed silica particles

    DOE Patents [OSTI]

    Grabbe, A.; Michalske, T.A.; Smith, W.L.

    1999-05-11

    Dehydroxylated, silica-containing, glass surfaces are known to be at least partially terminated by strained siloxane rings. According to the invention, a surface of this kind is exposed to a selected silane compound or mixture of silane compounds under reaction-promoting conditions. The ensuing reaction results in opening of the strained siloxane rings, and termination of surface atoms by chemical species, such as organic or organosilicon species, having desirable properties. These species can be chosen to provide qualities such as hydrophobicity, or improved coupling to a polymeric coating. 11 figs.

  2. Synthesis and properties of Chitosan-silica hybrid aerogels

    SciTech Connect (OSTI)

    Ayers, Michael R.; Hunt, Arlon J.

    2001-06-01

    Chitosan, a polymer that is soluble in dilute aqueous acid, is derived from chitin, a natural polyglucosamide. Aquagels where the solid phase consists of both chitosan and silica can be easily prepared by using an acidic solution of chitosan to catalyze the hydrolysis and condensation of tetraethylorthosilicate. Gels with chitosan/TEOS mass ratios of 0.1-1.1 have been prepared by this method. Standard drying processes using CO{sub 2} give the corresponding aerogels. The amount of chitosan in the gel plays a role in the shrinkage of the aerogel during drying. Gels with the lowest chitosan/silica ratios show the most linear shrinkage, up to 24%, while those with the highest ratios show only a 7% linear shrinkage. Pyrolysis at 700 C under nitrogen produces a darkened aerogel due to the thermal decomposition of the chitosan, however, the aerogel retains its monolithic form. The pyrolyzed aerogels absorb slightly more infrared radiation in the 2-5 {micro}m region than the original aerogels. B.E.T. surface areas of these aerogels range from 470-750 m{sup 2}/g. Biocompatibility screening of this material shows a very high value for hemolysis, but a low value for cytotoxicity.

  3. Silica separation from reinjection brines at Monte Amiata geothermal plants, Italy

    SciTech Connect (OSTI)

    Vitolo, S.; Cialdella, M.L. . Dipartimento di Ingegneria Chimica)

    1994-06-01

    A process for the separation of silica from geothermal reinjection brines is reported, in which the phases of coagulation, sedimentation and filtration of silica are involved. The effectiveness of lime and calcium chloride as coagulating agents has been investigated and the separating operations have been set out. Attention has been focused on Monte Amiata reinjection geothermal brines, whose scaling effect causes serious problems in the operation and maintenance of reinjection facilities. The study has been conducted using different amounts of added coagulants and at different temperatures, to determine optimal operating conditions. Though calcium chloride was revealed to be effective as a coagulant of the polymeric silica fraction, lime has also proved capable of removing monomeric dissolved silica at high dosages. Investigation on the behavior of coagulated brine has revealed the feasibility of separating the coagulated silica by sedimentation and filtration.

  4. Characterization of zirconia- and niobia-silica mixture coatings produced by ion-beam sputtering

    SciTech Connect (OSTI)

    Melninkaitis, Andrius; Tolenis, Tomas; Mazule, Lina; Mirauskas, Julius; Sirutkaitis, Valdas; Mangote, Benoit; Fu Xinghai; Zerrad, Myriam; Gallais, Laurent; Commandre, Mireille; Kicas, Simonas; Drazdys, Ramutis

    2011-03-20

    ZrO{sub 2}-SiO{sub 2} and Nb{sub 2}O{sub 5}-SiO{sub 2} mixture coatings as well as those of pure zirconia (ZrO{sub 2}), niobia (Nb{sub 2}O{sub 5}), and silica (SiO{sub 2}) deposited by ion-beam sputtering were investigated. Refractive-index dispersions, bandgaps, and volumetric fractions of materials in mixed coatings were analyzed from spectrophotometric data. Optical scattering, surface roughness, nanostructure, and optical resistance were also studied. Zirconia-silica mixtures experience the transition from crystalline to amorphous phase by increasing the content of SiO{sub 2}. This also results in reduced surface roughness. All niobia and silica coatings and their mixtures were amorphous. The obtained laser-induced damage thresholds in the subpicosecond range also correlates with respect to the silica content in both zirconia- and niobia-silica mixtures.

  5. Mesoporous silica nanoparticles for biomedical and catalytical applications

    SciTech Connect (OSTI)

    Sun, Xiaoxing

    2011-05-15

    Mesoporous silica materials, discovered in 1992 by the Mobile Oil Corporation, have received considerable attention in the chemical industry due to their superior textual properties such as high surface area, large pore volume, tunable pore diameter, and narrow pore size distribution. Among those materials, MCM-41, referred to Mobile Composition of Matter NO. 41, contains honeycomb liked porous structure that is the most common mesoporous molecular sieve studied. Applications of MCM-41 type mesoporous silica material in biomedical field as well as catalytical field have been developed and discussed in this thesis. The unique features of mesoporous silica nanoparticles were utilized for the design of delivery system for multiple biomolecules as described in chapter 2. We loaded luciferin into the hexagonal channels of MSN and capped the pore ends with gold nanoparticles to prevent premature release. Luciferase was adsorbed onto the outer surface of the MSN. Both the MSN and the gold nanoparticles were protected by poly-ethylene glycol to minimize nonspecific interaction of luciferase and keep it from denaturating. Controlled release of luciferin was triggered within the cells and the enzymatic reaction was detected by a luminometer. Further developments by varying enzyme/substrate pairs may provide opportunities to control cell behavior and manipulate intracellular reactions. MSN was also served as a noble metal catalyst support due to its large surface area and its stability with active metals. We prepared MSN with pore diameter of 10 nm (LP10-MSN) which can facilitate mass transfer. And we successfully synthesized an organo silane, 2,2'-Bipyridine-amide-triethoxylsilane (Bpy-amide-TES). Then we were able to functionalize LP10-MSN with bipyridinyl group by both post-grafting method and co-condensation method. Future research of this material would be platinum complexation. This Pt (II) complex catalyst has been reported for a C-H bond activation reaction as an alternative of the traditional Friedel-Crafts reaction. And we will compare the turnover numbers of MSN supported material with homogenous catalyst to evaluate the catalytical efficiency of our material.

  6. Nanoporous silica-based protocells at multiple scales for designs of life and nanomedicine

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sun, Jie; Jakobsson, Eric; Wang, Yingxiao; Brinker, C. Jeffrey

    2015-01-19

    In this study, various protocell models have been constructed de novo with the bottom-up approach. Here we describe a silica-based protocell composed of a nanoporous amorphous silica core encapsulated within a lipid bilayer built by self-assembly that provides for independent definition of cell interior and the surface membrane. In this review, we will first describe the essential features of this architecture and then summarize the current development of silica-based protocells at both micro- and nanoscale with diverse functionalities. As the structure of the silica is relatively static, silica-core protocells do not have the ability to change shape, but their interiormore » structure provides a highly crowded and, in some cases, authentic scaffold upon which biomolecular components and systems could be reconstituted. In basic research, the larger protocells based on precise silica replicas of cells could be developed into geometrically realistic bioreactor platforms to enable cellular functions like coupled biochemical reactions, while in translational research smaller protocells based on mesoporous silica nanoparticles are being developed for targeted nanomedicine. Ultimately we see two different motivations for protocell research and development: (1) to emulate life in order to understand it; and (2) to use biomimicry to engineer desired cellular interactions.« less

  7. Encapsulated in silica: genome, proteome and physiology of the thermophilic bacterium Anoxybacillus flavithermus

    SciTech Connect (OSTI)

    Saw, Jimmy H; Mountain, Bruce W; Feng, Lu; Omelchenko, Marina V; Saito, Jennifer A; Stott, Matthew B; Li, Dan; Zhao, Guang; Wu, Junli; Galperin, Michael Y; Dunfield, Peter F; Wang, Lei; Alam, Maqsudul

    2008-01-01

    Gram-positive bacteria of the genus Anoxybacillus have been found in diverse thermophilic habitats, such as geothermal hot springs and manure, and in processed foods such as gelatin and milk powder. Anoxybacillus flavithermus is a facultatively anaerobic bacterium found in super-saturated silica solutions and in opaline silica sinter. The ability of A. flavithermus to grow in super-saturated silica solutions makes it an ideal subject to study the processes of sinter formation, which might be similar to the biomineralization processes that occurred at the dawn of life. We report here the complete genome sequence of A. flavithermus strain WK1, isolated from the waste water drain at the Wairakei geothermal power station in New Zealand. It consists of a single chromosome of 2,846,746 base pairs and is predicted to encode 2,863 proteins. In silico genome analysis identified several enzymes that could be involved in silica adaptation and biofilm formation, and their predicted functions were experimentally validated in vitro. Proteomic analysis confirmed the regulation of biofilm-related proteins and crucial enzymes for the synthesis of long-chain polyamines as constituents of silica nanospheres. Microbial fossils preserved in silica and silica sinters are excellent objects for studying ancient life, a new paleobiological frontier. An integrated analysis of the A. flavithermus genome and proteome provides the first glimpse of metabolic adaptation during silicification and sinter formation. Comparative genome analysis suggests an extensive gene loss in the Anoxybacillus/Geobacillus branch after its divergence from other bacilli.

  8. Nanoporous silica-based protocells at multiple scales for designs of life and nanomedicine

    SciTech Connect (OSTI)

    Sun, Jie; Jakobsson, Eric; Wang, Yingxiao; Brinker, C. Jeffrey

    2015-01-19

    In this study, various protocell models have been constructed de novo with the bottom-up approach. Here we describe a silica-based protocell composed of a nanoporous amorphous silica core encapsulated within a lipid bilayer built by self-assembly that provides for independent definition of cell interior and the surface membrane. In this review, we will first describe the essential features of this architecture and then summarize the current development of silica-based protocells at both micro- and nanoscale with diverse functionalities. As the structure of the silica is relatively static, silica-core protocells do not have the ability to change shape, but their interior structure provides a highly crowded and, in some cases, authentic scaffold upon which biomolecular components and systems could be reconstituted. In basic research, the larger protocells based on precise silica replicas of cells could be developed into geometrically realistic bioreactor platforms to enable cellular functions like coupled biochemical reactions, while in translational research smaller protocells based on mesoporous silica nanoparticles are being developed for targeted nanomedicine. Ultimately we see two different motivations for protocell research and development: (1) to emulate life in order to understand it; and (2) to use biomimicry to engineer desired cellular interactions.

  9. Synthesis of superparamagnetic silica-coated magnetite nanoparticles for biomedical applications

    SciTech Connect (OSTI)

    Kaur, Navjot Chudasama, Bhupendra

    2015-05-15

    Multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) coated with silica are widely researched for biomedical applications such as magnetic resonance imaging, tissue repair, cell separation, hyperthermia, drug delivery, etc. In this article synthesis of magnetite (Fe{sub 3}O{sub 4}) nanoparticles and their coating with SiO{sub 2} is reported. Fe{sub 3}O{sub 4} nanoparticles were synthesized by chemical co-precipitation and it was coated with silica by hydrolysis and condensation of tetraethylorthosilicate. XRD, FTIR, TEM and VSM techniques were used to characterize bare and coated nanoparticles. Results indicated that the average size of SPIONS was 8.4?nm. X-ray diffraction patterns of silica coated SPIONS were identical to that of SPIONS confirming the inner spinal structure of SPIONS. FTIR results confirmed the binding of silica with the magnetite and the formation of the silica shell around the magnetite core. Magnetic properties of SPIONS and silica coated SPIONS are determined by VSM. They are superparamagnetic. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated magnetite-silica core-shell nanostructures with tailored morphology and excellent magnetic properties.

  10. Non-blinking single-photon emitters in silica

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; Stam, Ward van der; Vanmaekelbergh, Daniel; Koenderink, A. Femius; Krauss, Todd D.; Donega, Celso de Mello

    2016-02-19

    Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters,more » do not blink, and have photoluminescence lifetimes of a few nanoseconds. Furthermore, photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots.« less

  11. Influence of lithium hydroxide on alkali-silica reaction

    SciTech Connect (OSTI)

    Bulteel, D.; Garcia-Diaz, E.; Degrugilliers, P.

    2010-04-15

    Several papers show that the use of lithium limits the development of alkali-silica reaction (ASR) in concrete. The aim of this study is to improve the understanding of lithium's role on the alteration mechanism of ASR. The approach used is a chemical method which allowed a quantitative measurement of the specific degree of reaction of ASR. The chemical concrete sub-system used, called model reactor, is composed of the main ASR reagents: reactive aggregate, portlandite and alkaline solution. Different reaction degrees are measured and compared for different alkaline solutions: NaOH, KOH and LiOH. Alteration by ASR is observed with the same reaction degrees in the presence of NaOH and KOH, accompanied by the consumption of hydroxyl concentration. On the other hand with LiOH, ASR is very limited. Reaction degree values evolve little and the hydroxyl concentration remains about stable. These observations demonstrate that lithium ions have an inhibitor role on ASR.

  12. Sealed, nozzle-mix burners for silica deposition

    DOE Patents [OSTI]

    Adler, Meryle D. M.; Brown, John T.; Misra, Mahendra K.

    2003-07-08

    Burners (40) for producing fused silica boules are provided. The burners employ a tube-in-tube (301-306) design with flats (56, 50) on some of the tubes (305, 301) being used to limit the cross-sectional area of certain passages (206, 202) within the burner and/or to atomize a silicon-containing, liquid source material, such as OMCTS. To avoid the possibility of flashback, the burner has separate passages for fuel (205) and oxygen (204, 206), i.e., the burner employs nozzle mixing, rather than premixing, of the fuel and oxygen. The burners are installed in burner holes (26) formed in the crown (20) of a furnace and form a seal with those holes so that ambient air cannot be entrained into the furnace through the holes. An external air cooled jacket (60) can be used to hold the temperature of the burner below a prescribed upper limit, e.g., 400.degree. C.

  13. Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Eedugurala, Naresh; Wang, Zhuoran; Chaudhary, Umesh; Nelson, Nicholas; Kandel, Kapil; Kobayashi, Takeshi; Slowing, Igor I.; Pruski, Marek; Sadow, Aaron D.

    2015-11-04

    The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpinmore » moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. These supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites.« less

  14. Does elevated CO2 alter silica uptake in trees?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fulweiler, Robinson W.; Maguire, Timothy J.; Carey, Joanna C.; Finzi, Adrien C.

    2015-01-13

    Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO2 fertilization, longterm free-air CO2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine), and five hardwoodmore » species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.« less

  15. Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports

    SciTech Connect (OSTI)

    Keith James Stanger

    2003-05-31

    The tethered, chiral, chelating diphosphine rhodium complex, which catalyzes the enantioselective hydrogenation of methyl-{alpha}-acetamidocinnamate (MAC), has the illustrated structure as established by {sup 31}P NMR and IR studies. Spectral and catalytic investigations also suggest that the mechanism of action of the tethered complex is the same as that of the untethered complex in solution. The rhodium complexes, [Rh(COD)H]{sub 4}, [Rh(COD){sub 2}]{sup +}BF{sub 4}{sup -}, [Rh(COD)Cl]{sub 2}, and RhCl{sub 3} {center_dot} 3H{sub 2}O, adsorbed on SiO{sub 2} are optimally activated for toluene hydrogenation by pretreatment with H{sub 2} at 200 C. The same complexes on Pd-SiO{sub 2} are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominantly fluorocyclohexane in heptane and 1,2-dichloroethane solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst [-S(CH{sub 2}){sub 3}s-]Re(O)(Me)(PPh{sub 3}) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recyclability, extended stability, and increased resistance to deactivation.

  16. Titania-Activated Silica System for Emission Control | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Titania-Activated Silica System for Emission Control Titania-Activated Silica System for Emission Control Silica-Titania Composite (STC) Technology Safely and Cost-Effectively Removes Mercury from End-Box Exhaust in Chlor-Alkali Facilities The chlor-alkali industry produces valuable chemicals such as chlorine, hydrogen, and caustic soda. In 2001, between 150 and 200 chlor-alkali facilities throughout the world used the mercury-cell process. Although this process uses the mercury in a closed-loop

  17. Cooling rate and stress relaxation in silica melts and glasses via microsecond molecular dyanmics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lane, J. Matthew D.

    2015-07-22

    We have conducted extremely long molecular dynamics simulations of glasses to microsecond times, which close the gap between experimental and atomistic simulation time scales by two to three orders of magnitude. The static, thermal, and structural properties of silica glass are reported for glass cooling rates down to 5×109 K/s and viscoelastic response in silica melts and glasses are studied over nine decades of time. We finally present results from relaxation of hydrostatic compressive stress in silica and show that time-temperature superposition holds in these systems for temperatures from 3500 to 1000 K.

  18. Comprehensive Study of the Impact of Steam on Polyethyleneimine on Silica

    Office of Scientific and Technical Information (OSTI)

    for CO{sub 2} Capture (Journal Article) | SciTech Connect Comprehensive Study of the Impact of Steam on Polyethyleneimine on Silica for CO{sub 2} Capture Citation Details In-Document Search Title: Comprehensive Study of the Impact of Steam on Polyethyleneimine on Silica for CO{sub 2} Capture An amine sorbent, prepared by impregnation of polyethyleneimine on silica, was tested for steam stability. The stability of the sorbent was investigated in a fixed bed reactor using multiple steam cycles

  19. Cooling rate and stress relaxation in silica melts and glasses via microsecond molecular dyanmics

    SciTech Connect (OSTI)

    Lane, J. Matthew D.

    2015-07-22

    We have conducted extremely long molecular dynamics simulations of glasses to microsecond times, which close the gap between experimental and atomistic simulation time scales by two to three orders of magnitude. The static, thermal, and structural properties of silica glass are reported for glass cooling rates down to 5×109 K/s and viscoelastic response in silica melts and glasses are studied over nine decades of time. We finally present results from relaxation of hydrostatic compressive stress in silica and show that time-temperature superposition holds in these systems for temperatures from 3500 to 1000 K.

  20. Crystallized alkali-silica gel in concrete from the late 1890s

    SciTech Connect (OSTI)

    Peterson, Karl . E-mail: cee@mtu.edu; Gress, David . E-mail: dlgress@unh.edu; Van Dam, Tom . E-mail: cee@mtu.edu; Sutter, Lawrence . E-mail: cee@mtu.edu

    2006-08-15

    The Elon Farnsworth Battery, a concrete structure completed in 1898, is in an advanced state of disrepair. To investigate the potential for rehabilitation, cores were extracted from the battery. Petrographic examination revealed abundant deposits of alkali silica reaction products in cracks associated with the quartz rich metasedimentary coarse aggregate. The products of the alkali silica reaction are variable in composition and morphology, including both amorphous and crystalline phases. The crystalline alkali silica reaction products are characterized by quantitative X-ray energy dispersive spectrometry (EDX) and X-ray diffraction (XRD). The broad extent of the reactivity is likely due to elevated alkali levels in the cements used.

  1. Synthesis of silica coated zinc oxide-poly(ethylene-co-acrylic...

    Office of Scientific and Technical Information (OSTI)

    silica shell was made on ZnO nanoparticles. * PEAA, an interfacial agent is used to make nanocomposite-polymer matrix by twin-screw extruder. * Si-ZnOPEAA matrix is highly ...

  2. Suitability of Silica Gel to Process INEEL Sodium Bearing Waste - Letter Report

    SciTech Connect (OSTI)

    Kirkham, Robert John; Herbst, Alan Keith

    2000-09-01

    The suitability of using the silica gel process for Idaho National Engineering and Environmental Laboratory (INEEL) sodium bearing waste was investigated during fiscal year 2000. The study was co-funded by the Tanks Focus Area as part of TTP No. ID-77WT-31 and the High Level Waste Program. The task also included the investigation of possible other absorbents. Scoping tests and examination of past work showed that the silica gel absorption/adsorption and drying method was the most promising; thus only silica gel was studied and not other absorbents. The documentation on the Russian silica gel process provided much of the needed information but did not provide some of the processing detail so these facts had to be inferred or gleaned from the literature.

  3. Method for inhibiting silica precipitation and scaling in geothermal flow systems

    DOE Patents [OSTI]

    Harrar, J.E.; Lorensen, L.E.; Locke, F.E.

    1980-06-13

    A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds is described.

  4. Method for inhibiting silica precipitation and scaling in geothermal flow systems

    DOE Patents [OSTI]

    Harrar, Jackson E.; Lorensen, Lyman E.; Locke, Frank E.

    1982-01-01

    A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds.

  5. Petrography study of two siliceous limestones submitted to alkali-silica reaction

    SciTech Connect (OSTI)

    Monnin, Y. . E-mail: monnin@ensm-douai.fr; Degrugilliers, P.; Bulteel, D.; Garcia-Diaz, E.

    2006-08-15

    This study presents the contribution of petrography to the comprehension of the alkali-silica reaction mechanism applied to two siliceous limestones. A petrography study was made on the two aggregates before reaction to define their relative proportions and types of reactive silica and to observe their distribution in the microstructure. Then a model reactor, constituted by the reactive siliceous limestone aggregate, portlandite and NaOH, was used to measure the swelling due to reaction of the silica with alkalis and the free expansion of the aggregates. The volume evolution between both aggregates was very different and could be explained by the preliminary petrographic study. It appears that the swelling of the aggregates is conditioned by the microstructure of the carbonated matrix, the quantity and the distribution of the reactive silica.

  6. Oxidative alteration of spent fuel in a silica-rich environment: SEM/AEM

    Office of Scientific and Technical Information (OSTI)

    investigation and geochemical modeling (Conference) | SciTech Connect Oxidative alteration of spent fuel in a silica-rich environment: SEM/AEM investigation and geochemical modeling Citation Details In-Document Search Title: Oxidative alteration of spent fuel in a silica-rich environment: SEM/AEM investigation and geochemical modeling Correctly identifying the possible alteration products and accurately predicting their occurrence in a repository-relevant environment are the key for the

  7. Luminescent studies of fluorescent chromophore-doped silica aerogels for flat panel display applications

    SciTech Connect (OSTI)

    Glauser, S.A.C. [California Univ., Davis, CA (United States). Dept. of Applied Science; Lee, H.W.H. [Lawrence Livermore National Lab., CA (United States)

    1997-04-01

    The remarkable optical and electronic properties of doped and undoped silica aerogels establish their utility as unique, mulitfunctional host materials for fluorescent dyes and other luminescent materials for display and imaging applications. We present results on the photoluminescence, absorption, and photoluminescence excitation spectra of undoped silica aerogels and aerogels doped with Er{sup 3+}, rhodamine 6G (R6G), and fluorescein. 4 refs., 12 figs.

  8. Effect of Bubbles and Silica Dissolution on Melter Feed Rheology during

    Office of Scientific and Technical Information (OSTI)

    Conversion to Glass (Journal Article) | SciTech Connect Journal Article: Effect of Bubbles and Silica Dissolution on Melter Feed Rheology during Conversion to Glass Citation Details In-Document Search Title: Effect of Bubbles and Silica Dissolution on Melter Feed Rheology during Conversion to Glass As the nuclear waste glass melter feed is converted to molten glass, the feed becomes a continuous glass-forming melt where dissolving refractory constituents are suspended together with numerous

  9. Particle Restabilization in Silica/PEG/Ethanol Suspensions: How Strongly do

    Office of Scientific and Technical Information (OSTI)

    Polymers Need To Adsorb To Stabilize Against Aggregation? (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Particle Restabilization in Silica/PEG/Ethanol Suspensions: How Strongly do Polymers Need To Adsorb To Stabilize Against Aggregation? Citation Details In-Document Search Title: Particle Restabilization in Silica/PEG/Ethanol Suspensions: How Strongly do Polymers Need To Adsorb To Stabilize Against Aggregation? We study the effects of increasing the

  10. "Multifunctional Mesoporous Silica Catalyst" Patent Awarded | The Ames

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laboratory "Multifunctional Mesoporous Silica Catalyst" Patent Awarded Congratulations to the late Victor Lin, Show-Ling Lee, Chih-Hsiang Tsai, Hung-Ting Chen, Marek Pruski and Takeshi Kobayashi for being awarded a patent on "Multifunctional Mesoporous Silica Catalyst", issued on March 31, 2015. U.S. Patent No. 8,993,793 can be viewed on the U.S. Patent and Trademark Office website.

  11. The Effect of Foaming and Silica Dissolution on Melter Feed Rheology during

    Office of Scientific and Technical Information (OSTI)

    Conversion to Glass (Conference) | SciTech Connect Conference: The Effect of Foaming and Silica Dissolution on Melter Feed Rheology during Conversion to Glass Citation Details In-Document Search Title: The Effect of Foaming and Silica Dissolution on Melter Feed Rheology during Conversion to Glass As the nuclear waste glass melter feed is converted to molten glass, the feed eventually becomes a continuous glass-forming melt in which dissolving refractory constituents are suspended together

  12. Mathematical modeling of silica deposition in Tongonan-I reinjection wells, Philippines

    SciTech Connect (OSTI)

    Malate, R.C.M.; O`Sullivan, M.J.

    1993-10-01

    Mathematical models of silica deposition are derived using the method of characteristics for the problem of variable rate injection into a well producing radially symmetric flow. Solutions are developed using the first order rate equation of silica deposition suggested by Rimstidt and Barnes (1980). The changes in porosity and permeability resulting from deposition are included in the models. The models developed are successfully applied in simulating the changes in injection capacity in some of the reinjection wells in Tongonan geothermal field, Philippines.

  13. Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

    SciTech Connect (OSTI)

    Eedugurala, Naresh; Wang, Zhuoran; Chaudhary, Umesh; Nelson, Nicholas; Kandel, Kapil; Kobayashi, Takeshi; Slowing, Igor I.; Pruski, Marek; Sadow, Aaron D.

    2015-11-04

    The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpin moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. These supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites.

  14. Controllable synthesis of hollow mesoporous silica spheres and application as support of nano-gold

    SciTech Connect (OSTI)

    Wang, Tao; Ma, Weihua Shangguan, Junnan; Jiang, Wei; Zhong, Qin

    2014-07-01

    Hollow silica spheres with mesoporous structure were synthesized by sol–gel/emulsion method. In the process, the surfactant, cetyltrimethylammonium bromide (CTAB) was used to stabilize the oil droplet and also used as structure direct agent. The diameter of the hollow silica spheres, ranging from 895 nm to 157 nm, can be controlled by changing the ratio of ethanol to water and the concentration of the surfactant as well. The shell thickness of the spheres decreased when the ratio of ethanol to water decreased. The proposed mechanism of the formation of silica spheres could elucidate the experimental results well. Furthermore, the resultant hollow mesoporous silica spheres were then employed as support of nano-gold which was used to catalyze the isomerization reaction of propylene oxide to produce allyl alcohol. - Graphical abstract: It is the schematic mechanism for the formation of hollow mesoporous silica spheres. - Highlights: • The formation mechanism of the hollow spheres is proposed. • The isomerization of propylene oxide can be catalyzed by the nano-gold/SiO{sub 2}. • The hollow silica spheres can be prepared controllably.

  15. Swimming motility reduces Azotobacter vinelandii deposition to silica surfaces

    SciTech Connect (OSTI)

    Lu, Nanxi; Massoudieh, Arash; Liang, Xiaomeng; Hu, Dehong; Kamai, Tamir; Ginn, Timothy R.; Zilles, Julie L.; Nguyen, Thanh H.

    2015-09-16

    The role of swimming motility on bacterial transport and fate in porous media was evaluated. We present microscopic evidence showing that strong swimming motility reduces attachment of Azotobacter vinelandii cells to silica surfaces. Applying global and cluster statistical analyses to microscopic videos taken under non-flow conditions, wild type, flagellated A. vinelandii strain DJ showed strong swimming ability with an average speed of 13.1 ?m/s, DJ77 showed impaired swimming averaged at 8.7 ?m/s, and both the non-flagellated JZ52 and chemically treated DJ cells were non-motile. Quantitative analyses of trajectories observed at different distances above the collector of a radial stagnation point flow cell (RSPF) revealed that both swimming and non-swimming cells moved with the flow when at a distance of at least 20 ?m from the collector surface. Near the surface, DJ cells showed both horizontal and vertical movement diverging them from reaching surfaces, while chemically treated DJ cells moved with the flow to reach surfaces, suggesting that strong swimming reduced attachment. In agreement with the RSPF results, the deposition rates obtained for two-dimensional multiple-collector micromodels were also lowest for DJ, while DJ77 and JZ52 showed similar values. Strong swimming specifically reduced deposition on the upstream surfaces of the micromodel collectors.

  16. Implantation conditions for diamond nanocrystal formation in amorphous silica

    SciTech Connect (OSTI)

    Buljan, Maja; Radovic, Iva Bogdanovic; Desnica, Uros V.; Ivanda, Mile; Jaksic, Milko; Saguy, Cecile; Kalish, Rafi; Djerdj, Igor; Tonejc, Andelka; Gamulin, Ozren

    2008-08-01

    We present a study of carbon ion implantation in amorphous silica, which, followed by annealing in a hydrogen-rich environment, leads to preferential formation of carbon nanocrystals with cubic diamond (c-diamond), face-centered cubic (n-diamond), or simple cubic (i-carbon) carbon crystal lattices. Two different annealing treatments were used: furnace annealing for 1 h and rapid thermal annealing for a brief period, which enables monitoring of early nucleation events. The influence of implanted dose and annealing type on carbon and hydrogen concentrations, clustering, and bonding were investigated. Rutherford backscattering, elastic recoil detection analysis, infrared spectroscopy, transmission electron microscopy, selected area electron diffraction, ultraviolet-visible absorption measurements, and Raman spectroscopy were used to study these carbon formations. These results, combined with the results of previous investigations on similar systems, show that preferential formation of different carbon phases (diamond, n-diamond, or i-carbon) depends on implantation energy, implantation dose, and annealing conditions. Diamond nanocrystals formed at a relatively low carbon volume density are achieved by deeper implantation and/or lower implanted dose. Higher volume densities led to n-diamond and finally to i-carbon crystal formation. This observed behavior is related to damage sites induced by implantation. The optical properties of different carbon nanocrystal phases were significantly different.

  17. Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

    SciTech Connect (OSTI)

    Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang Gao, Ziwei

    2015-01-15

    A successive anchoring of Ti(NMe{sub 2}){sub 4}, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, {sup 13}C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands. - Graphical abstract: The ligand-tailored silica supported “single site” titanium complexes were synthesized by SOMC strategy and fully characterized. Their catalytic activity were evaluated by benzaldehyde silylcyanation. - Highlights: • Single-site silica supported Ti active species was prepared by SOMC technique. • O-donor ligand tailored Ti surface species was synthesized. • The surface species was characterized by XPS, {sup 13}C CP-MAS NMR, XANES etc. • Catalytic activity of the Ti active species in silylcyanation reaction was evaluated.

  18. Solidification of Acidic, High Nitrate Nuclear Wastes by Grouting or Absorption on Silica Gel

    SciTech Connect (OSTI)

    A. K. Herbst; S. V. Raman; R. J. Kirkham

    2004-01-01

    The use of grout and silica gel were explored for the solidification of four types of acidic, high nitrate radioactive wastes. Two methods of grouting were tested: direct grouting and pre-neutralization. Two methods of absorption on silica gel were also tested: direct absorption and rotary spray drying. The waste simulant acidity varied between 1 N and 12 N. The waste simulant was neutralized by pre-blending calcium hydroxide with Portland cement and blast furnace slag powders prior to mixing with the simulant for grout solidification. Liquid sodium hydroxide was used to partially neutralize the simulant to a pH above 2 and then it was absorbed for silica gel solidification. Formulations for each of these methods are presented along with waste form characteristics and properties. Compositional variation maps for grout formulations are presented which help determine the optimum "recipe" for a particular waste stream. These maps provide a method to determine the proportions of waste, calcium hydroxide, Portland cement, and blast furnace slag that provide a waste form that meets the disposal acceptance criteria. The maps guide researchers in selecting areas to study and provide an operational envelop that produces acceptable waste forms. The grouts both solidify and stabilize the wastes, while absorption on silica gel produces a solid waste that will not pass standard leaching procedures (TCLP) if required. Silica gel wastes can be made to pass most leach tests if heated to 600C.

  19. Thickness controlled sol-gel silica films for plasmonic bio-sensing devices

    SciTech Connect (OSTI)

    Figus, Cristiana Quochi, Francesco Artizzu, Flavia Saba, Michele Marongiu, Daniela Mura, Andrea; Bongiovanni, Giovanni; Floris, Francesco; Marabelli, Franco; Patrini, Maddalena; Fornasari, Lucia; Pellacani, Paola; Valsesia, Andrea

    2014-10-21

    Plasmonics has recently received considerable interest due to its potentiality in many fields as well as in nanobio-technology applications. In this regard, various strategies are required for modifying the surfaces of plasmonic nanostructures and to control their optical properties in view of interesting application such as bio-sensing, We report a simple method for depositing silica layers of controlled thickness on planar plasmonic structures. Tetraethoxysilane (TEOS) was used as silica precursor. The control of the silica layer thickness was obtained by optimizing the sol-gel method and dip-coating technique, in particular by properly tuning different parameters such as pH, solvent concentration, and withdrawal speed. The resulting films were characterized via atomic force microscopy (AFM), Fourier-transform (FT) spectroscopy, and spectroscopic ellipsometry (SE). Furthermore, by performing the analysis of surface plasmon resonances before and after the coating of the nanostructures, it was observed that the position of the resonance structures could be properly shifted by finely controlling the silica layer thickness. The effect of silica coating was assessed also in view of sensing applications, due to important advantages, such as surface protection of the plasmonic structure.

  20. Synthesis of palladium-doped silica nanofibers by sol-gel reaction and electrospinning process

    SciTech Connect (OSTI)

    San, Thiam Hui; Daud, Wan Ramli Wan; Kadhum, Abdul Amir Hassan; Mohamad, Abu Bakar; Kamarudin, Siti Kartom; Shyuan, Loh Kee; Majlan, Edy Herianto [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia and Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2012-06-29

    Nanofiber is drawing great attention nowadays with their high surface area per volume and flexibility in surface functionalities that make them favorable as a proton exchange membrane in fuel cell application. In this study, incorporation of palladium nanoparticles in silica nanofibers was prepared by combination of a tetraorthosilane (TEOS) sol-gel reaction with electrospinning process. This method can prevent the nanoparticles from aggregation by direct mixing of palladium nanoparticles in silica sol. The as-produced electrospun fibers were thermally treated to remove poly(vinyl pyrrolidone) (PVP) and condensation of silanol in silica framework. PVP is chosen as fiber shaping agent because of its insulting and capping properties for various metal nanoparticles. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the silica fibers and Pd nanoparticles on the fibers. Spun fibers with average diameter ranged from 100nm to 400nm were obtained at optimum operating condition and distribution of Pd nanoparticles on silica fibers was investigated.

  1. Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry

    SciTech Connect (OSTI)

    Khan, Saad A.: Fedkiw Peter S.; Baker, Gregory L.

    2007-01-24

    The ultimate objectives of this research are to understand the principles underpinning nano-composite polymer electrolytes (CPEs) and facilitate development of novel CPEs that are low-cost, have high conductivities, large Li+ transference numbers, improved electrolyte-electrode interfacial stability, yield long cycle life, exhibit mechanical stability and are easily processable. Our approach is to use nanoparticulate silica fillers to formulate novel composite electrolytes consisting of surface-modified fumed silica nano-particles in polyethylene oxides (PEO) in the presence of lithium salts. We intend to design single-ion conducting silica nanoparticles which provide CPEs with high Li+ transference numbers. We also will develop low-Mw (molecular weight), high-Mw and crosslinked PEO electrolytes with tunable properties in terms of conductivity, transference number, interfacial stability, processability and mechanical strength

  2. SANS study of interaction of silica nanoparticles with BSA protein and their resultant structure

    SciTech Connect (OSTI)

    Yadav, Indresh, E-mail: vkaswal@barc.gov.in; Aswal, V. K., E-mail: vkaswal@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 PSI Villigen Switzerland (Switzerland)

    2014-04-24

    Small angle neutron scattering (SANS) has been carried out to study the interaction of anionic silica nanoparticles (88 ) with globular protein Bovine Serum Albumin (BSA) (M.W. 66.4 kD) in aqueous solution. The measurements have been carried out on fixed concentration (1 wt %) of Ludox silica nanoparticles with varying concentration of BSA (05 wt %) at pH7. Results show that silica nanoparticles and BSA coexist as individual entities at low concentration of BSA where electrostatic repulsive interactions between them prevent their aggregation. However, as the concentration of BSA increases (? 0.5 wt %), it induces the attractive depletion interaction among nanoparticles leading to finally their aggregation at higher BSA concentration (2 wt %). The aggregates are found to be governed by the diffusion limited aggregation (DLA) morphology of fractal nature having fractal dimension about 2.4.

  3. Subcarbonyl species of molybdenum hexacarbonyl supported on silica: A DRIFT study

    SciTech Connect (OSTI)

    Kurhinen, M.; Venaelaeinen, T.; Pakkanen, T.A. )

    1994-10-06

    Subspecies of partially decarbonylated molybdenum hexacarbonyl supported on silica were studied by diffuse reflectance IR spectroscopy. Mo(CO)[sub 6]/SiO[sub 2] was prepared in a fluidized bed reactor by vapor-phase adsorption of molybdenum hexacarbonyl under nitrogen flow. Decarbonylation begins when Mo(CO)[sub 6] has adsorbed onto the silica. Dehydroxylation of the support during calcination facilitates the formation of subspecies of Mo(CO)[sub 6]. The activation energy needed for bond formation between a transition metal and silica and for decarbonylation is lower than the desorption energy of physisorbed Mo(CO)[sub 6], and this was seen in the IR spectra as a disappearance of bands due to subspecies. When the supported Mo(CO)[sub 6] was reheated the physisorption bands were the last to disappear from the IR spectra. 37 refs., 6 figs., 2 tabs.

  4. Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

    DOE Patents [OSTI]

    Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

    2006-05-02

    An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

  5. Dating thermal events at Cerro Prieto using fission-track annealing

    SciTech Connect (OSTI)

    Sanford, S.J.; Elders, W.A.

    1981-01-01

    The duration of heating in the Cerro Prieto reservoir was estimated by relating the fading of spontaneous fission tracks in detrital apatite to observed temperatures. The rate of fading is a function of both time and temperature. The apparent fission track age of the detrital apatites then, is a function of both their source age and their time-temperature history. Data from laboratory experiments and geologic fading studies were compiled from published sources to produce lines of iso-annealing for apatite in time-temperature space. Fission track ages were calculated for samples from two wells at Cerro Prieto, one with an apparently simple and one with an apparently complex thermal history. Temperatures were estimated by empirical vitrinite reflectance geothermometry, fluid inclusion homogenization and oxygen isotope equilibrium. These estimates were compared with logs of measured borehole temperatures. The temperature in well T-366, where complete annealing first occurs, was estimated to be between 160 and 180{sup 0}C. Complete annealing at these temperatures requires 10{sup 4} and 10{sup 3} years, respectively. Well M-94 has an apparently complex thermal history. Geothermometers in this well indicate temperatures some 50 to 100{sup 0}C higher than those measured directly in the borehole. Fission tracks are partially preserved in M-94 where paleotemperatures were as high as 200{sup 0}C and are erased where geothermometers indicate temperatures of 250{sup 0}C. This implies a thermal event less than 10{sup 1} years and greater than 10{sup 0} years in duration.

  6. A comparison of mechanical properties and scaling law relationships for silica aerogels and their organic counterparts

    SciTech Connect (OSTI)

    Pekala, R.W.; Hrubesh, L.W.; Tillotson, T.M.; Alviso, C.T.; Poco, J.F.; LeMay, J.D.

    1990-08-01

    Aerogels are a special class of open-cell foams derived from the supercritical extraction of highly crosslinked, inorganic or organic gels. The resultant materials have ultrafine cell/pore sizes (< 100 nm), high surface areas (350--1000m{sup 2}/g), and a microstructure composed of interconnected colloidal-like particles or polymeric chains with characteristic diameters of 10 nm. TEM and SAXS show that this microstructure is sensitive to variations in processing conditions that influence crosslinking chemistry and growth processes prior to gelation. Traditional silica aerogels are prepared via the hydrolysis and condensation of tetramethoxy silane (TMOS) or tetraethoxy silane (TEOS). Factors such as pH and the (H{sub 2}O)/(TMOS) ratio affect the microstructure of the dried aerogel. It is generally accepted that polymeric' silica aerogels result from acid catalysis while colloidal'silica aerogels result from base catalysis. Recently, Hrubesh and Tillotson developed a new condensed silica' procedure for obtaining silica aerogels with densities as low as 0.004g/cc, i.e. only 3{times} the density of air. Organic aerogels are formed from the aqueous, polycondensation of (1) resorcinol/formaldehyde or (2) melamine/formaldehyde. The microstructure of the resorcinol-formaldehyde (RF) aerogels is dictated by the amount of base catalyst used in the sol-gel polymerization. In addition, these materials can be pyrolyzed in an inert atmosphere to form vitreous carbon aerogels. Melamine- formaldehyde (MF) aerogels that are both colorless and transparent are only formed under acidic conditions (i.e. pH = 1--2). In this paper, the microstructural dependence and scaling law relationships for the compressive modulus of silica, carbon, RF, and MF aerogels will be discussed in detail. 17 refs., 1 fig.

  7. Evaluation of an ambient air sampling system for tritium (as tritiated water vapor) using silica gel adsorbent columns

    SciTech Connect (OSTI)

    Patton, G.W.; Cooper, A.T.; Tinker, M.R.

    1995-08-01

    Ambient air samples for tritium analysis (as the tritiated water vapor [HTO] content of atmospheric moisture) are collected for the Hanford Site Surface Environmental Surveillance Project (SESP) using the solid adsorbent silica gel. The silica gel has a moisture sensitive indicator which allows for visual observation of moisture movement through a column. Despite using an established method, some silica gel columns showed a complete change in the color indicator for summertime samples suggesting that breakthrough had occurred; thus a series of tests was conducted on the sampling system in an environmental chamber. The purpose of this study was to determine the maximum practical sampling volume and overall collection efficiency for water vapor collected on silica gel columns. Another purpose was to demonstrate the use of an impinger-based system to load water vapor onto silica gel columns to provide realistic analytical spikes and blanks for the Hanford Site SESP. Breakthrough volumes (V{sub b}) were measured and the chromatographic efficiency (expressed as the number of theoretical plates [N]) was calculated for a range of environmental conditions. Tests involved visual observations of the change in the silica gel`s color indicator as a moist air stream was drawn through the column, measurement of the amount of a tritium tracer retained and then recovered from the silica gel, and gravimetric analysis for silica gel columns exposed in the environmental chamber.

  8. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    SciTech Connect (OSTI)

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In addition, Pt-mesoporous silica core-shell structured NPs (Pt{at}mSiO{sub 2}) were prepared, where the individual Pt NP is encapsulated by the mesoporous silica layer. The Pt{at}mSiO{sub 2} catalysts showed promising catalytic activity in high temperature CO oxidation. The design of catalytic structures with tunable parameters by rational synthetic methods presents a major advance in the field of catalyst synthesis, which would lead to uncover the structure-function relationships in heterogeneous catalytic reactions.

  9. Applications of Geothermally-Produced Colloidal Silica in Reservoir Management - Smart Gels

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Hunt, Jonathan

    In enhanced geothermal systems (EGS) the reservoir permeability is often enhanced or created using hydraulic fracturing. In hydraulic fracturing, high fluid pressures are applied to confined zones in the subsurface usually using packers to fracture the host rock. This enhances rock permeability and therefore conductive heat transfer to the circulating geothermal fluid (e.g. water or supercritical carbon dioxide). The ultimate goal is to increase or improve the thermal energy production from the subsurface by either optimal designs of injection and production wells or by altering the fracture permeability to create different zones of circulation that can be exploited in geothermal heat extraction. Moreover, hydraulic fracturing can lead to the creation of undesirable short-circuits or fast flow-paths between the injection and extraction wells leading to a short thermal residence time, low heat recovery, and thus a short-life of the EGS. A potential remedy to these problems is to deploy a cementing (blocking, diverting) agent to minimize short-cuts and/or create new circulation cells for heat extraction. A potential diverting agent is the colloidal silica by-product that can be co-produced from geothermal fluids. Silica gels are abundant in various surface and subsurface applications, yet they have not been evaluated for EGS applications. In this study we are investigating the benefits of silica gel deployment on thermal response of an EGS, either by blocking short-circuiting undesirable pathways as a result of diverting the geofluid to other fractures; or creating, within fractures, new circulation cells for harvesting heat through newly active surface area contact. A significant advantage of colloidal silica is that it can be co-produced from geothermal fluids using an inexpensive membrane-based separation technology that was developed previously using DOE-GTP funding. This co-produced silica has properties that potentially make it useful as a fluid diversion agent for subsurface applications. Colloidal silica solutions exist as low-viscosity fluids during their induction period but then undergo a rapid increase in viscosity (gelation) to form a solid gel. The length of the induction period can be manipulated by varying the properties of the solution, such as silica concentration and colloid size. We believe it is possible to produce colloidal silica gels suitable for use as diverting agents for blocking undesirable fast-paths which result in short-circuiting the EGS once hydraulic fracturing has been deployed. In addition, the gels could be used in conventional geothermal fields to increase overall energy recovery by modifying flow.

  10. Applications of Geothermally-Produced Colloidal Silica in Reservoir Management - Smart Gels

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Hunt, Jonathan

    2013-01-31

    In enhanced geothermal systems (EGS) the reservoir permeability is often enhanced or created using hydraulic fracturing. In hydraulic fracturing, high fluid pressures are applied to confined zones in the subsurface usually using packers to fracture the host rock. This enhances rock permeability and therefore conductive heat transfer to the circulating geothermal fluid (e.g. water or supercritical carbon dioxide). The ultimate goal is to increase or improve the thermal energy production from the subsurface by either optimal designs of injection and production wells or by altering the fracture permeability to create different zones of circulation that can be exploited in geothermal heat extraction. Moreover, hydraulic fracturing can lead to the creation of undesirable short-circuits or fast flow-paths between the injection and extraction wells leading to a short thermal residence time, low heat recovery, and thus a short-life of the EGS. A potential remedy to these problems is to deploy a cementing (blocking, diverting) agent to minimize short-cuts and/or create new circulation cells for heat extraction. A potential diverting agent is the colloidal silica by-product that can be co-produced from geothermal fluids. Silica gels are abundant in various surface and subsurface applications, yet they have not been evaluated for EGS applications. In this study we are investigating the benefits of silica gel deployment on thermal response of an EGS, either by blocking short-circuiting undesirable pathways as a result of diverting the geofluid to other fractures; or creating, within fractures, new circulation cells for harvesting heat through newly active surface area contact. A significant advantage of colloidal silica is that it can be co-produced from geothermal fluids using an inexpensive membrane-based separation technology that was developed previously using DOE-GTP funding. This co-produced silica has properties that potentially make it useful as a fluid diversion agent for subsurface applications. Colloidal silica solutions exist as low-viscosity fluids during their induction period but then undergo a rapid increase in viscosity (gelation) to form a solid gel. The length of the induction period can be manipulated by varying the properties of the solution, such as silica concentration and colloid size. We believe it is possible to produce colloidal silica gels suitable for use as diverting agents for blocking undesirable fast-paths which result in short-circuiting the EGS once hydraulic fracturing has been deployed. In addition, the gels could be used in conventional geothermal fields to increase overall energy recovery by modifying flow.

  11. Probing the Silica/Polysiloxane Interface: A Solid State NMR Investigation

    Office of Scientific and Technical Information (OSTI)

    of y-Irradiated Composite Materials (Journal Article) | SciTech Connect Probing the Silica/Polysiloxane Interface: A Solid State NMR Investigation of y-Irradiated Composite Materials Citation Details In-Document Search Title: Probing the Silica/Polysiloxane Interface: A Solid State NMR Investigation of y-Irradiated Composite Materials Authors: Mayer, B P ; Chinn, S C ; Maxwell, R S ; Reimer, J A Publication Date: 2011-04-06 OSTI Identifier: 1213656 Report Number(s): LLNL-JRNL-479454 DOE

  12. Method and composition in which metal hydride particles are embedded in a silica network

    DOE Patents [OSTI]

    Heung, Leung K.

    1999-01-01

    A silica embedded metal hydride composition and a method for making such a composition. The composition is made via the following process: A quantity of fumed silica is blended with water to make a paste. After adding metal hydride particles, the paste is dried to form a solid. According to one embodiment of the invention, the solid is ground into granules for use of the product in hydrogen storage. Alternatively, the paste can be molded into plates or cylinders and then dried for use of the product as a hydrogen filter. Where mechanical strength is required, the paste can be impregnated in a porous substrate or wire network.

  13. Applications of Geothermally-Produced Colloidal Silica in Reservoir Management - Smart Gels

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Hunt, Jonathan

    2013-01-31

    In enhanced geothermal systems (EGS) the reservoir permeability is often enhanced or created using hydraulic fracturing. In hydraulic fracturing, high fluid pressures are applied to confined zones in the subsurface usually using packers to fracture the host rock. This enhances rock permeability and therefore conductive heat transfer to the circulating geothermal fluid (e.g. water or supercritical carbon dioxide). The ultimate goal is to increase or improve the thermal energy production from the subsurface by either optimal designs of injection and production wells or by altering the fracture permeability to create different zones of circulation that can be exploited in geothermal heat extraction. Moreover, hydraulic fracturing can lead to the creation of undesirable short-circuits or fast flow-paths between the injection and extraction wells leading to a short thermal residence time, low heat recovery, and thus a short-life of the EGS. A potential remedy to these problems is to deploy a cementing (blocking, diverting) agent to minimize short-cuts and/or create new circulation cells for heat extraction. A potential diverting agent is the colloidal silica by-product that can be co-produced from geothermal fluids. Silica gels are abundant in various surface and subsurface applications, yet they have not been evaluated for EGS applications. In this study we are investigating the benefits of silica gel deployment on thermal response of an EGS, either by blocking short-circuiting undesirable pathways as a result of diverting the geofluid to other fractures; or creating, within fractures, new circulation cells for harvesting heat through newly active surface area contact. A significant advantage of colloidal silica is that it can be co-produced from geothermal fluids using an inexpensive membrane-based separation technology that was developed previously using DOE-GTP funding. This co-produced silica has properties that potentially make it useful as a fluid diversion agent for subsurface applications. Colloidal silica solutions exist as low-viscosity fluids during their “induction period” but then undergo a rapid increase in viscosity (gelation) to form a solid gel. The length of the induction period can be manipulated by varying the properties of the solution, such as silica concentration and colloid size. We believe it is possible to produce colloidal silica gels suitable for use as diverting agents for blocking undesirable fast-paths which result in short-circuiting the EGS once hydraulic fracturing has been deployed. In addition, the gels could be used in conventional geothermal fields to increase overall energy recovery by modifying flow.

  14. Grafting Strategy to Develop Single Site Titanium on an Amorphous Silica Surface

    SciTech Connect (OSTI)

    Capel-Sanchez, M.; Blanco-Brieva, G; Campos-Martin, J; de Frutos, M; Wen, W; Rodriguez, J; Fierro, J

    2009-01-01

    Titanium/silica systems were prepared by grafting a titanium alkoxide (titanium isopropoxide and titanium (triethanolaminate) isopropoxide) precursor onto amorphous silica. The grafting process, which consisted of the hydrolysis of the Ti precursor by the hydroxyl groups on the silica surface, yielded samples containing Ti-loadings of 1-1.6 wt %. The as synthesized and calcined TiO2-SiO2 samples were characterized by UV-vis, FTIR, XPS, and XANES spectroscopic techniques. These systems were tested in the liquid-phase epoxidation of oct-1-ene with hydrogen peroxide reaction. Spectroscopic data indicated that titanium anchoring takes place by reaction between the alkoxide precursor and surface OH groups of the silica substrate. The nature of surface titanium species generated by chemical grafting depends largely on the titanium precursor employed. Thus, the titanium isopropoxide precursor yields tetrahedrally coordinated polymeric titanium species, which give rise to a low-efficiency catalyst. However, if an atrane precursor (titanium (triethanolaminate) isopropoxide) is employed, isolated titanium species are obtained. The fact that these species remain isolated even after calcination is due to the protective effect of the triethanolaminate ligand that avoids titanium polymerization. These differences in the titanium environment have a pivotal role in the performance of these systems in the epoxidation of alkenes with hydrogen peroxide.

  15. Silica-alumina trihydrate filled epoxy castings resistant to arced SF.sub.6

    DOE Patents [OSTI]

    Chenoweth, Terrence E.; Yeoman, Frederick A.

    1978-01-01

    A cured, insulating, casting composition, having a coefficient of linear thermal expansion of below about 38 .times. 10.sup.-6 in./in./.degree. C and being resistant to arced sulfur hexafluoride gas, in contact with a metal surface in a sulfur hexafluoride gas environment, is made from hydantoin epoxy resin, anhydride curing agent and a filler combination of fused silica and alumina trihydrate.

  16. Biogenic silica fluxes and accumulation rates in the Gulf of California

    SciTech Connect (OSTI)

    Thunell, R.C.; Pride, C.J.; Tappa, E. ); Muller-Karger, F.E. )

    1994-04-01

    The Gulf of California, though small in size, plays an important role in the global silica cycle. The seasonal pattern of biogenic silica flux in the gulf is closely related to that of phytoplankton biomass levels and is controlled by changes in weather and hydrographic conditions. The highest opal fluxes ([approximately] 0.35 g[center dot]m[sup [minus]2][center dot]d[sup [minus]1]) occur during winter and spring, and they are comparable to those measured in some of the most productive ecosystems of the world. Approximately 15%-25% of the biogenic silica produced in surface waters is preserved in gulf sediments, a figure significantly higher than the average global ocean preservation rate. However, the flux of opal at 500 m water depth is less than 25% of that being produced at the surface, suggesting that most of the recycling of biogenic silica in the Gulf of California occurs in the upper water column. 28 refs., 3 figs.

  17. Thermal stability of bimetallic Au/Fe nanoparticles in silica matrix

    SciTech Connect (OSTI)

    Pannu, Compesh Singh, Udai B. Hooda, Sonu Kabiraj, D. Avasthi, D. K.

    2014-04-24

    Thin silica film containing Au and Fe bimetallic nanoparticles were prepared by atom beam cosputtering. The samples were annealed at different temperatures from 400 to 800° C to study the thermal stability of bimetallic nanoparticles using X ray diffraction. It is observed that at 800° C strong structural rearrangement took place leading to thermal decomposition of bimetallic nanoparticles.

  18. RADIOLOGICAL RELEASES DUE TO AIR AND SILICA DUST ACTIVATION IN EMPLACEMENT DRIFTS

    SciTech Connect (OSTI)

    J.S. Tang

    2003-05-07

    The purpose of this calculation is to determine the quantity and significance of annual Monitored Geologic Repository (MGR) subsurface normal radiological releases due to neutron activation of air and silica dust in emplacement drifts. This calculation includes the following items: (1) Calculate activation of ventilation airflow through emplacement drifts to quantify radioactive gaseous releases; and (2) Calculate the bounding potential activated silica dust concentration and releases. The sources of silica dust may arise from air supply to emplacement drifts as well as host rock around emplacement drifts. For this calculation, the source of dust is conservatively assumed to be the host rock (Assumption 3.6), which is subject to long-term neutron exposure resulting in saturated radioactivity. The scope of this calculation is limited to releases from activated air and silica dust only, excluding natural radioactive releases such as radon or releases from defective waste packages (breached or contaminated). This work supports the repository ventilation system design and Preclosure Safety Analysis. This includes MGR items classified as Quality Level 1, for example, the Uncanistered Spent Nuclear Fuel Waste Package (CRWMS M&O [Civilian Radioactive Waste Management and Operation Contractor] 1999a, page 7). Therefore, this calculation is subject to the requirements of the ''Quality Assurance Requirements and Description'' (DOE [U.S. Department of Energy] 2003). The performance of the calculation and development of this document are carried out in accordance with AP-3.12Q, ''Design Calculation and Analyses'' and LP-3.30Q-BSC, ''Hazards Analysis System''.

  19. Femtosecond laser ablation dynamics of fused silica extracted from oscillation of time-resolved reflectivity

    SciTech Connect (OSTI)

    Kumada, Takayuki Akagi, Hiroshi; Itakura, Ryuji; Otobe, Tomohito; Yokoyama, Atsushi

    2014-03-14

    Femtosecond laser ablation dynamics of fused silica is examined via time-resolved reflectivity measurements. After optical breakdown was caused by irradiation of a pump pulse with fluence F{sub pump}?=?3.314.9?J/cm{sup 2}, the reflectivity oscillated with a period of 63??2 ps for a wavelength ??=?795?nm. The period was reduced by half for ??=?398?nm. We ascribe the oscillation to the interference between the probe pulses reflected from the front and rear surfaces of the photo-excited molten fused silica layer. The time-resolved reflectivity agrees closely with a model comprising a photo-excited layer which expands due to the formation of voids, and then separates into two parts, one of which is left on the sample surface and the other separated as a molten thin layer from the surface by the spallation mechanism. Such oscillations were not observed in the reflectivity of soda-lime glass. Whether the reflectivity oscillates or not probably depends on the layer viscosity while in a molten state. Since viscosity of the molten fused silica is several orders of magnitude higher than that of the soda-lime glass at the same temperature, fused silica forms a molten thin layer that reflects the probe pulse, whereas the soda-lime glass is fragmented into clusters.

  20. Biological Applications and Transmission Electron Microscopy Investigations of Mesoporous Silica Nanoparticles

    SciTech Connect (OSTI)

    Brian G. Trewyn

    2006-05-01

    The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). Mesoporous silica nanoparticles organically functionalized shown to undergo endocytosis in cancer cells and drug release from the pores was controlled intracellularly and intercellularly. Transmission electron microscopy investigations demonstrated the variety of morphologies produced in this field of mesoporous silica nanomaterial synthesis. A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both KeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the antioxidant dependent release was measured. Finally, the biological interaction of the material was determined along with TEM measurements. An electron investigation proved that the pore openings of the MSN were indeed blocked by the Fe{sub 3}O{sub 4} nanoparticles. The biological interaction investigation demonstrated Fe{sub 3}O{sub 4}-capped MSN endocytosis into HeLa cells. Not only does the material enter the cells through endocytosis, but it seems that fluorescein was released from the pores most probably caused by disulfide bond reducing molecules, antioxidants. In addition to endocytosis and release, the Fe{sub 3}O{sub 4}-capped MSN propelled the cells across a cuvette upon induction of a magnet force. Finally, an important aspect of materials characterization is transmission electron microscopy. A TEM investigation demonstrated that incorporating different functional groups during the synthesis (co-condensation) changed the particle and pore morphologies.

  1. Mesoporous silica film from a solution containing a surfactant and methods of making same

    DOE Patents [OSTI]

    Liu, Jun [West Richland, WA; Domansky, Karel [Cambridge, MA; Li, Xiaohong [Richland, WA; Fryxell, Glen E. [Kennewick, WA; Baskaran, Suresh [Kennewick, WA; Kohler, Nathan J. [Richland, WA; Thevuthasan, Suntharampillai [Kennewick, WA; Coyle, Christopher A. [Richland, WA; Birnbaum, Jerome C. [Richland, WA

    2001-12-11

    The present invention is a mesoporous silica film having a low dielectric constant and method of making having the steps of combining a surfactant in a silica precursor solution, spin-coating a film from this solution mixture, forming a partially hydroxylated mesoporous film, and dehydroxylating the hydroxylated film to obtain the mesoporous film. It is advantageous that the small polyoxyethylene ether surfactants used in spin-coated films as described in the present invention will result in fine pores smaller on average than about 20 nm. The resulting mesoporous film has a dielectric constant less than 3, which is stable in moist air with a specific humidity. The present invention provides a method for superior control of film thickness and thickness uniformity over a coated wafer, and films with low dielectric constant.

  2. Microstructural Changes Due to Alkali-Silica Reaction during Standard Mortar Test

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shin, Jun-Ho; Struble, Leslie; Kirkpatrick, R.

    2015-12-01

    The microstructural development of mortar bars with silica glass aggregate undergoing alkali-silica reaction (ASR) under the conditions of American Society for Testing and Materials (ASTM) Standard Test C1260 was analyzed using scanning electron microscopy and qualitative X-ray microanalysis. Cracking in the aggregate, the hydrated paste, and the paste-aggregate interface was important in the development of the microstructure. Cracks were characterized according to their location, their relationship to other cracks, and whether they are filled with ASR gel. Expansion of the bars was approximately 1% at 12 days and 2% at 53 days. They fell apart by 63 days. The barsmore » contained two zones, an inner region that was undergoing ASR and an outer and much more highly damaged zone that extended further inward over time. Evidence of ASR was present even during the period when specimens were immersed in water, prior to immersion in NaOH solution.« less

  3. Experimental stress–strain analysis of tapered silica optical fibers with nanofiber waist

    SciTech Connect (OSTI)

    Holleis, S.; Hoinkes, T.; Wuttke, C.; Schneeweiss, P.; Rauschenbeutel, A.

    2014-04-21

    We experimentally determine tensile force–elongation diagrams of tapered optical fibers with a nanofiber waist. The tapered optical fibers are produced from standard silica optical fibers using a heat and pull process. Both, the force–elongation data and scanning electron microscope images of the rupture points indicate a brittle material. Despite the small waist radii of only a few hundred nanometers, our experimental data can be fully explained by a nonlinear stress–strain model that relies on material properties of macroscopic silica optical fibers. This is an important asset when it comes to designing miniaturized optical elements as one can rely on the well-founded material characteristics of standard optical fibers. Based on this understanding, we demonstrate a simple and non-destructive technique that allows us to determine the waist radius of the tapered optical fiber. We find excellent agreement with independent scanning electron microscope measurements of the waist radius.

  4. Investigating the mesostructure of ordered porous silica nanocomposites by transmission electron microscopy techniques

    SciTech Connect (OSTI)

    Bullita, S.; Casula, M. F.; Piludu, M.; Falqui, A.; Carta, D.; Corrias, A.

    2014-10-21

    Nanocomposites made out of FeCo alloy nanocrystals supported onto pre-formed mesoporous ordered silica which features a cubic arrangement of pores (SBA-16) were investigated. Information on the effect of the nanocrystals on the mesostructure (i.e. pore arrangement symmetry, pore size, and shape) were deduced by a multitechnique approach including N2 physisorption, low angle X-ray diffraction, and Transmission electron microscopy. It is shown that advanced transmission electron microscopy techniques are required, however, to gain direct evidence on key compositional and textural features of the nanocomposites. In particular, electron tomography and microtomy techniques make clear that the FeCo nanocrystals are located within the pores of the SBA-16 silica, and that the ordered mesostructure of the nanocomposite is retained throughout the observed specimen.

  5. Fracture Induced Sub-Band Absorption as a Precursor to Optical Damage on Fused Silica Surfaces

    SciTech Connect (OSTI)

    Miller, P E; Bude, J D; Suratwala, T I; Shen, N; Laurence, T A; Steele, W A; Menapace, J; Feit, M D; Wong, L L

    2010-03-05

    The optical damage threshold of indentation induced flaws on fused silica surfaces was explored. Mechanical flaws were characterized by laser damaged testing, SEM, optical, and photoluminescence microscopy. Localized polishing, chemical etching, and the control of indentation morphology were used to isolate the structural features which limit optical damage. A thin defect layer on fracture surfaces, including those smaller than the wavelength of visible light, was found to be the dominant source of laser damage initiation during illumination with 355nm, 3ns laser pulses. Little evidence was found that either displaced or densified material or fluence intensification plays a significant role in optical damage at fluences >35J/cm{sup 2}. Elimination of the defect layer was shown to increase the overall damage performance of fused silica optics.

  6. Detection of alkali-silica reaction swelling in concrete by staining

    DOE Patents [OSTI]

    Guthrie, Jr., George D.; Carey, J. William

    1998-01-01

    A method using concentrated aqueous solutions of sodium cobaltinitrite and rhodamine B is described which can be used to identify concrete that contains gels formed by the alkali-silica reaction (ASR). These solutions present little health or environmental risk, are readily applied, and rapidly discriminate between two chemically distinct gels; K-rich, Na--K--Ca--Si gels are identified by yellow staining, and alkali-poor, Ca--Si gels are identified by pink staining.

  7. Detection of alkali-silica reaction swelling in concrete by staining

    DOE Patents [OSTI]

    Guthrie, G.D. Jr.; Carey, J.W.

    1998-04-14

    A method using concentrated aqueous solutions of sodium cobalt nitrite and rhodamine B is described which can be used to identify concrete that contains gels formed by the alkali-silica reaction (ASR). These solutions present little health or environmental risk, are readily applied, and rapidly discriminate between two chemically distinct gels; K-rich, Na-K-Ca-Si gels are identified by yellow staining, and alkali-poor, Ca-Si gels are identified by pink staining.

  8. Origins of secondary silica within Yucca Mountain, Nye County, southwestern Nevada

    SciTech Connect (OSTI)

    Moscati, R.J.; Whelan, J.F.

    1996-09-01

    The accuracy of predictions of the hydrologic response of Yucca Mountain to future climate depends largely on how well relations between past climate and hydrology can be resolved. To advance this reconstruction, secondary minerals in and near Yucca Mountain, deposited by ground waters that originated both as surficial recharge at Yucca Mountain and from regional aquifers, are being studied to determine past ground-water sources and chemistries. Preliminary data on stable oxygen isotopes indicate that, although silica (opal, quartz, and chalcedony) and calcite and have formed in similar settings and from somewhat similar fluids, the authors have found no compelling evidence of coprecipitation or formation from identical fluids. If verified by further analyses, this precludes the use of silica-calcite mineral pairs for precise geothermometry. The preliminary data also indicate that opal and calcite occurrences in pedogenic and unsaturated-zone settings are invariably compatible with formation under modern ambient surface or subsurface temperatures. Silica and calcite stable-isotope studies are being integrated with soil geochemical modeling. This modeling will define the soil geochemical condition (climate) leading to opal or calcite deposition and to the transfer functions that may apply at the meteorologic soil unsaturated-zone interfaces. Additional study of pedogenic and unsaturated-zone silica is needed to support these models. The hypothesis that the transformation of vapor-phase tridymite to quartz requires saturated conditions is being tested through stable oxygen-isotope studies of lithophysal tridymite/quartz mixtures. Should this hypothesis be verified, mineralogic analysis by X-ray diffraction theoretically would permit reconstruction of past maximum water-table elevations.

  9. Controlled epitaxial growth of mesoporous silica/gold nanorod nanolollipops and nanodumb-bells

    SciTech Connect (OSTI)

    Huang, Ching-Mao; Chung, Ming-Fang; Lo, Leu-Wei; Souris, Jeffrey S.

    2014-11-01

    In this work, we describe the controlled synthesis of novel heterogeneous nanostructures comprised of mesoporous silica-coated gold nanorods (MSGNRs) in the form of coreshell nanolollipops and nanodumb-bells, using a seed-mediated solgel method. Although MSGNR coreshell (?-MSGNR) structures have been reported previously by us and others, we herein discuss the first ever fabrication of MSGNR nanolollipops (?-MSGNR) and nanodumb-bells (?-MSGNR), achieved by simply controlling the aging time of gold nanorods (GNRs), the residual cetyltrimethylammonium bromide (CTAB) coating of GNRs, and the addition of dimethyl formamide during incubation, centrifugation, and sonication, respectively. Transmission electron microscopy revealed two bare GNR isoforms, with aspect ratios of approximately 4 and 6, while scanning electron microscopy was used to further elucidate the morphology of ?-MSGNR and ?-MSGNR heterostructures. In agreement with the smaller dielectric constants afforded by incomplete silica encasement, spectroscopic studies of ?-MSGNR and ?-MSGNR, surface plasmon resonance (SPR) bands revealed 20-40 nm blue shifts relative to the SPR of ?-MSGNR. On the basis of the attributes and applications of more conventional ?-MSGNRs, ?-MSGNRs and ?-MSGNRs are anticipated to provide most of the utility of ?-MSGNRs, but with the additional functionalities that accompany their incorporation of both bare gold and mesoporous silica encased tips; with significant/unique implications for biomedical and catalytic applications.

  10. Sorption Behavior of Strontium-85 Onto Colloids of Silica and Smectite

    SciTech Connect (OSTI)

    Lu, N.; Triay, I.R.; Mason, C.F.V.; Longmire, P.A.

    1998-11-10

    Strontium-90 is one of the sizable radioactive contaminants found in DP Canyon at Los Alamos, New Mexico. Radioactive surveys found the {sup 90}Sr is present in surface and groundwater in DP Canyon and Los Alamos Canyon. Colloids may influence the transport of this radionuclide in surface water and groundwater environments in both canyons. In this study, we investigated the sorption/desorption behavior of Sr on colloids of smectite and silica. Laboratory batch sorption experiments were conducted using {sup 85}Sr as a surrogate to {sup 90}Sr. Groundwater, collected from DP Canyon and from Well J-13 at Yucca Mountain, Nevada, and deionized water were used in this study. Our results show that 92% to 100% of {sup 85}Sr was rapidly adsorbed onto smectite colloids in all three waters. The concentrations of Ca{sup 2+} significantly influence the adsorption of {sup 85}Sr onto silica colloids. Desorption of {sup 85}Sr from smectite colloids is much slower than the sorption process. Desorption of {sup 85}Sr from silica colloids was rapid in DP groundwater and slow using J-13 groundwater and deionized water.

  11. Synthesis and characterization of pharmaceutical surfactant templated mesoporous silica: Its application to controlled delivery of duloxetine

    SciTech Connect (OSTI)

    Mani, Ganesh; Pushparaj, Hemalatha; Peng, Mei Mei; Muthiahpillai, Palanichamy; Udhumansha, Ubaidulla; Jang, Hyun Tae

    2014-03-01

    Graphical abstract: - Highlights: Usefulness of dual pharmaceutical surfactants in silica synthesis was evaluated. Effects of concentration of secondary template (Tween-40) were studied. Effects of fixed solvothermal condition on mesostructure formation were studied. Duloxetine drug loading capability was studied. Sustained release of duloxetine was evaluated. - Abstract: A new group of mesoporous silica nanoparticles (MSNs) were synthesized using combination pharmaceutical surfactants, Triton X-100 and Tween-40 as template and loaded with duloxetine hydrochloride (DX), for improving the sustained release of DX and patterns with high drug loading. Agglomerated spherical silica MSNs were synthesized by solgel and solvothermal methods. The calcined and drug loaded MSNs were characterized using X-ray diffraction (XRD), BraunnerEmmettTeller (BET), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), diffuse reflectance ultravioletvisible (DRS-UVvis) spectroscopy. MSNs with high surface area and pore volume were selected and studied for their DX loading and release. The selected MSNs can accommodate a maximum of 34% DX within it. About 90% was released at 200 h and hence, the synthesized MSNs were capable of engulfing DX and sustain its release. Further form the Ritger and Peppas, Higuchi model for mechanism drug release from all the MSN matrices follows anomalous transport or Non-Fickian diffusion with the r and n value 0.9 and 0.45 < n < 1, respectively. So, from this study it could be concluded that the MSNs synthesized using pharmaceutical templates were better choice of reservoir for the controlled delivery of drug which requires sustained release.

  12. Distribution of 1-Butyl-3-methylimidazolium Bistrifluoromethylsulfonimide in Mesoporous Silica as a Function of Pore Filling

    SciTech Connect (OSTI)

    Han, Kee Sung; Wang, Xiqing; Hagaman, Edward {Ed} W; Dai, Sheng

    2013-01-01

    Rotational dynamics of the ionic liquid (IL) 1-butyl-3-methlyimidazolium bistrifluoromethylsulfonimide, [C4mim][Tf2N], 1, as a neat liquid and confined in mesoporous silica were investigated by 1H spin-spin (T2) and spin-lattice (T1) relaxation measurements and 13C NMR spectroscopy. Translational dynamics (self-diffusion) were monitored via the diffusion coefficient, D, obtained with 1H pulsed field gradient NMR measurements. These data were used to determine the distribution of 1 in the pores of KIT-6, a mesoporous silica with a bicontinuous gyroid pore structure, as a function of filling fraction. Relaxation studies performed as a function of filling factor and temperature, reveal a dynamic heterogeneity in both translational and rotational motions for 1 at filling factors, f, = 0.2-1.0 (f = 1 corresponds to fully filled pores). Spin-lattice and spin-spin relaxation times reveal the motion of 1 in silica mesopores conform to that expected for a two-dimensional relaxation model. The relaxation dynamics are interpreted using a two-state, fast exchange model for all motions; a slow rotation (and translation) of molecules in contact with the surface and a faster motion approximated by the values for bulk relaxation and diffusion. 1 retains liquid like behavior at all filling factors and temperatures that extend to ca. 50 degrees below the bulk melting point. Translational motion in these systems, interpreted with MD-simulated diffusivity limits, confirms the high propensity of 1 to form a monolayer film on the silica surface at low filling factors.. The attractive interaction of 1 with the surface is greater than that for self-association of 1. The trends in diffusion data at short and long diffusion time suggest that the population of surface-bound 1 is in intimate contact with 1 in the pores. This condition is most easily met at higher filling fractions with successive additions of 1 increasing the layer thickness built up on the surface layer.

  13. Efficient photocatalytic hydrogen generation by silica supported and platinum promoted titanium dioxide

    SciTech Connect (OSTI)

    Joshi, Meenal M.; Labhsetwar, Nitin K.; Parwate, D.V.; Rayalu, Sadhana S.

    2013-09-01

    Graphical abstract: Titanium dioxide was supported on mesoporous silica and promoted with Pt and Ru. The supported photocatalysts show high surface area and better photocatalytic activity in visible light as compared to the benchmark Degussa P25. These photocatalysts were characterized using XRD, BET-SA, and UV-DRS techniques. The surface area of supported photocatalyst was 140.6 m{sup 2}/g which is higher than Degussa P-25. Supported photocatalyst was evaluated for hydrogen evolution via water splitting reaction using ethanol as a sacrificial donor. Hydrogen yield observed is 4791.43 ?mol/h/g of TiO{sub 2} and that for P-25 is 161 ?mol/h/g of TiO{sub 2} under visible light irradiation. The value is 30 times higher than benchmark material Degussa P-25. This photocatalyst is also found stable up to 24 h without replenishing with sacrificial donor ethanol. - Highlights: Semiconductor titanium dioxide has been supported on silica gel and promoted with Pt by simple wet impregnation route. This synthesized photocatalyst is showing high surface area of 140.6 m{sup 2}/g with crystallite size in the range of 15.44 ?. This photocatalyst is showing enhanced hydrogen yield of about 4791.43 ?mol/h/g of TiO{sub 2}. This photocatalyst is also found stable up to 24 h without replenishing with sacrificial donor ethanol. The effect of various operating parameters on supported photocatalyst also has been studied. - Abstract: Titanium dioxide was supported on mesoporous silica and promoted with Pt and Ru. The supported photocatalysts show high surface area and better photocatalytic activity in visible light as compared to the benchmark Degussa P25. These photocatalysts were characterized using XRD, BET-SA, and UV-DRS techniques. The surface area of supported photocatalyst was 140.6 m{sup 2}/g which is higher than Degussa P-25. Supported photocatalyst was evaluated for hydrogen evolution via water splitting reaction using ethanol as a sacrificial donor. Hydrogen yield observed is 4791.43 ?mol/h/g of TiO{sub 2} and that for P-25 is 161 ?mol/h/g of TiO{sub 2} under visible light irradiation. The value is 30 times higher than benchmark material Degussa P-25. This photocatalyst is also found stable up to 24 h without replenishing with sacrificial donor ethanol. However silica gel/TiO{sub 2}/Ru does not show any exciting result for hydrogen generation. The effect of various operating parameters like photocatalyst loading, Illumination time and intensity of light on supported photocatalyst also has been studied.

  14. Role of suprathermal electrons during nanosecond laser energy deposit in fused silica

    SciTech Connect (OSTI)

    Grua, P.; Hébert, D.; Lamaignère, L.; Rullier, J.-L.

    2014-08-25

    An accurate description of interaction between a nanosecond laser pulse and a wide band gap dielectric, such as fused silica, requires the understanding of energy deposit induced by temperature changes occurring in the material. In order to identify the fundamental processes involved in laser-matter interaction, we have used a 1D computational model that allows us to describe a wide set of physical mechanisms and intended for comparison with specially designed “1D experiments.” We have pointed out that suprathermal electrons are very likely implicated in heat conduction, and this assumption has allowed the model to reproduce the experiments.

  15. Synthesis and characterization of mesostructured silicas and gold frameworks as active matrices for biomolecule encapsulation.

    SciTech Connect (OSTI)

    Iton, L. E.; Crisci, A. J.; Vajdova, V.; Laible, P. D.; Burns, C. T.; Firestone, M. A.

    2006-01-01

    Interfacing of biomolecules to inorganic frameworks is essential for fabricating robust, functionally integrated biocomposites that may prove useful in a wide range of technologies including biocatalysis, biosensors or protein-based devices. Our work is directed at developing means to integrate biomolecules into mesostructured inorganics. These frameworks serve to both improve the mechanical stability of the proteins and to facilitate communication with them. Toward that end, we have synthesized and characterized mesoporous silicas and conductive metallic frameworks and have examined the encapsulation of both soluble (cytochrome c) and membrane proteins (bacteriorhodpsin) within them.

  16. Femtosecond laser pulse filamentation under anomalous dispersion in fused silica. Part 1. Numerical investigation

    SciTech Connect (OSTI)

    Smetanina, E O; Kompanets, V O; Chekalin, Sergei V; Kandidov, V P

    2012-10-31

    We report the results of investigation of femtosecond laser pulse filamentation in fused silica by varying the wavelength in the range from 800 to 2300 nm. It is shown that in the case of the anomalous group-velocity dispersion, a sequence of 'light bullets' with a high spatial and temporal localisation of the light field is formed along the filament. The relation of the formation and propagation of light bullets with the formation of an isolated anti-Stokes wing of the supercontinuum spectrum is established. (nonlinear optical phenomena)

  17. Dynamics of tungsten hexacarbonyl, dicobalt octacarbonyl, and their fragments adsorbed on silica surfaces

    SciTech Connect (OSTI)

    Muthukumar, Kaliappan; Valent, Roser; Jeschke, Harald O.

    2014-05-14

    Tungsten and cobalt carbonyls adsorbed on a substrate are typical starting points for the electron beam induced deposition of tungsten or cobalt based metallic nanostructures. We employ first principles molecular dynamics simulations to investigate the dynamics and vibrational spectra of W(CO){sub 6} and W(CO){sub 5} as well as Co{sub 2}(CO){sub 8} and Co(CO){sub 4} precursor molecules on fully and partially hydroxylated silica surfaces. Such surfaces resemble the initial conditions of electron beam induced growth processes. We find that both W(CO){sub 6} and Co{sub 2}(CO){sub 8} are stable at room temperature and mobile on a silica surface saturated with hydroxyl groups (OH), moving up to half an Angstrm per picosecond. In contrast, chemisorbed W(CO){sub 5} or Co(CO){sub 4} ions at room temperature do not change their binding site. These results contribute to gaining fundamental insight into how the molecules behave in the simulated time window of 20 ps and our determined vibrational spectra of all species provide signatures for experimentally distinguishing the form in which precursors cover a substrate.

  18. Biogenicity of silica precipitation around geysers and hot-spring vents, North Island, New Zealand

    SciTech Connect (OSTI)

    Jones, B.; Renaut, R.W.; Rosen, M.R.

    1997-01-01

    Before anthropogenic modifications, Ohaaki Pool (Broadlands-Ohaaki) and Dragon`s Mouth Geyser (Wairakei) emitted waters at temperatures of 93--98 C. The siliceous sinter that precipitated around their vents has the characteristics of geyserite, a dense laminated deposit of presumed abiogenic origin, that was precipitated from waters too hot (>73C) to support microbes other than thermophilic bacteria. Petrographic and SEM examinations of the sinters show that they incorporate columnar stromatolites and silicified, laminated stromatolitic mats that contain well-preserved filamentous microbes. At both localities the microbes lack evidence of desiccation or shrinkage, which implies that they were silicified rapidly at or shortly after their death. Although boiling and very hot (>90 C) waters were discharged, temperatures at many sites surrounding the vents remained sufficiently low and moist to support a microbial community that included thermophilic bacteria and cyanobacteria. In these cooler niches, the microbes and their biofilms served as highly favorable templates for the nucleation and growth of amorphous silica, and collectively provided a microbial framework for the laminated accretionary sinter. Some columnar, spicular, and stratiform geyserites are probably not abiotic precipitates, but are true silica stromatolites.

  19. High resolution transmission electron microscopy of melamine-formaldehyde aerogels and silica aerogels

    SciTech Connect (OSTI)

    Ruben, G.C. (Dartmouth Coll., Hanover, NH (United States). Dept. of Biological Sciences)

    1991-09-01

    The goal of the high resolution transmission electron microscopy (HRTEM) was to image the structure of two tetramethyl orthosilicate (TMOS) and two melamine-formaldehyde (MF) aerogels at the single polymer chain level{sup 1,2}. With this level of structural resolution we hoped to interrelate each aerogel's structure with its physical properties and its method of synthesis. Conventional single-step base catalysed TMOS aerogels show strings of spheroidal particles linked together with minimal necking. The spheroidal particles range from 86--132 {Angstrom} and average 113{plus minus}10 {Angstrom} in diameter{sup 2}. In contrast the TMOS aerogels reported on here were made by a two step method. After extended silica chains are grown in solution under acidic conditions with a substoichiometric amount of water, the reaction is stopped and the methanol hydrolysed from TMOS is removed. Then base catalysis and additional water are added to cause gel formation is a nonalcoholic solvent. The MF aerogels were prepared for HRTEM by fracturing them on a stereo microscope stage with razor knife so that fractured pieces with smooth flat surfaces could be selected for platinum-carbon replication. The two silica (TMOS) aerogels were both transparent and difficult to see. These aerogels were fractured on a stereo microscope stage with tweezers. 6 refs., 4 figs.

  20. Thermally Stable Nanocatalyst for High Temperature Reactions: Pt-Mesoporous Silica Core-Shell Nanoparticles

    SciTech Connect (OSTI)

    Joo, Sang Hoon; Park, J.Y.; Tsung, C.-K.; Yamada, Y.; Yang, P.; Somorjai, G.A.

    2008-10-25

    Recent advances in colloidal synthesis enabled the precise control of size, shape and composition of catalytic metal nanoparticles, allowing their use as model catalysts for systematic investigations of the atomic-scale properties affecting catalytic activity and selectivity. The organic capping agents stabilizing colloidal nanoparticles, however, often limit their application in high-temperature catalytic reactions. Here we report the design of a high-temperature stable model catalytic system that consists of Pt metal core coated with a mesoporous silica shell (Pt{at}mSiO{sub 2}). While inorganic silica shells encaged the Pt cores up to 750 C in air, the mesopores directly accessible to Pt cores made the Pt{at}mSiO{sub 2} nanoparticles as catalytically active as bare Pt metal for ethylene hydrogenation and CO oxidation. The high thermal stability of Pt{at}mSiO{sub 2} nanoparticles permitted high-temperature CO oxidation studies, including ignition behavior, which was not possible for bare Pt nanoparticles because of their deformation or aggregation. The results suggest that the Pt{at}mSiO{sub 2} nanoparticles are excellent nanocatalytic systems for high-temperature catalytic reactions or surface chemical processes, and the design concept employed in the Pt{at}mSiO{sub 2} core-shell catalyst can be extended to other metal-metal oxide compositions.

  1. SILICA GEL BEHAVIOR UNDER DIFFERENT EGS CHEMICAL AND THERMAL CONDITIONS: AN EXPERIMENTAL STUDY

    SciTech Connect (OSTI)

    Hunt, J D; Ezzedine, S M; Bourcier, W; Roberts, S

    2012-01-19

    Fractures and fracture networks are the principal pathways for migration of water and contaminants in groundwater systems, fluids in enhanced geothermal systems (EGS), oil and gas in petroleum reservoirs, carbon dioxide leakage from geological carbon sequestration, and radioactive and toxic industrial wastes from underground storage repositories. When dealing with EGS fracture networks, there are several major issues to consider, e.g., the minimization of hydraulic short circuits and losses of injected geothermal fluid to the surrounding formation, which in turn maximize heat extraction and economic production. Gel deployments to direct and control fluid flow have been extensively and successfully used in the oil industry for enhanced oil recovery. However, to the best of our knowledge, gels have not been applied to EGS to enhance heat extraction. In-situ gelling systems can either be organic or inorganic. Organic polymer gels are generally not thermostable to the typical temperatures of EGS systems. Inorganic gels, such as colloidal silica gels, however, may be ideal blocking agents for EGS systems if suitable gelation times can be achieved. In the current study, we explore colloidal silica gelation times and rheology as a function of SiO{sub 2} concentration, pH, salt concentration, and temperature, with preliminary results in the two-phase field above 100 C. Results at 25 C show that it may be possible to choose formulations that will gel in a reasonable and predictable amount of time at the temperatures of EGS systems.

  2. Vapor Sensing Using Conjugated Molecule-Linked Au Nanoparticles in a Silica Matrix

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dirk, Shawn M.; Howell, Stephen W.; Price, B. Katherine; Fan, Hongyou; Washburn, Cody; Wheeler, David R.; Tour, James M.; Whiting, Joshua; Simonson, R. Joseph

    2009-01-01

    Cross-linkedmore » assemblies of nanoparticles are of great value as chemiresistor-type sensors. Herein, we report a simple method to fabricate a chemiresistor-type sensor that minimizes the swelling transduction mechanism while optimizing the change in dielectric response. Sensors prepared with this methodology showed enhanced chemoselectivity for phosphonates which are useful surrogates for chemical weapons. Chemoselective sensors were fabricated using an aqueous solution of gold nanoparticles that were then cross-linked in the presence of the silica precursor, tetraethyl orthosilicate with the α -, ω -dithiolate (which is derived from the in situ deprotection of 1,4-di(Phenylethynyl- 4 ′ , 4 ″ -diacetylthio)-benzene ( 1 ) with wet triethylamine). The cross-linked nanoparticles and silica matrix were drop coated onto interdigitated electrodes having 8  μ m spacing. Samples were exposed to a series of analytes including dimethyl methylphosphonate (DMMP), octane, and toluene. A limit of detection was obtained for each analyte. Sensors assembled in this fashion were more sensitive to dimethyl methylphosphonate than to octane by a factor of 1000.« less

  3. Study on the thermal resistance in secondary particles chain of silica aerogel by molecular dynamics simulation

    SciTech Connect (OSTI)

    Liu, M. [Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing100190 (China); Department of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Qiu, L., E-mail: qiulin111@sina.com, E-mail: jzzhengxinghua@163.com; Zheng, X. H., E-mail: qiulin111@sina.com, E-mail: jzzhengxinghua@163.com; Zhu, J.; Tang, D. W. [Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing100190 (China)

    2014-09-07

    In this article, molecular dynamics simulation was performed to study the heat transport in secondary particles chain of silica aerogel. The two adjacent particles as the basic heat transport unit were modelled to characterize the heat transfer through the calculation of thermal resistance and vibrational density of states (VDOS). The total thermal resistance of two contact particles was predicted by non-equilibrium molecular dynamics simulations (NEMD). The defects were formed by deleting atoms in the system randomly first and performing heating and quenching process afterwards to achieve the DLCA (diffusive limited cluster-cluster aggregation) process. This kind of treatment showed a very reasonable prediction of thermal conductivity for the silica aerogels compared with the experimental values. The heat transport was great suppressed as the contact length increased or defect concentration increased. The constrain effect of heat transport was much significant when contact length fraction was in the small range (<0.5) or the defect concentration is in the high range (>0.5). Also, as the contact length increased, the role of joint thermal resistance played in the constraint of heat transport was increasing. However, the defect concentration did not affect the share of joint thermal resistance as the contact length did. VDOS of the system was calculated by numerical method to characterize the heat transport from atomic vibration view. The smaller contact length and greater defect concentration primarily affected the longitudinal acoustic modes, which ultimately influenced the heat transport between the adjacent particles.

  4. Pore-structure determinations of silica aerogels by {sup 129}Xe NMR spectroscopy and imaging.

    SciTech Connect (OSTI)

    Gregory, D. M.; Gerald, R. E., II; Botto, R. E.; Chemistry

    1998-04-01

    Silica aerogels represent a new class of open-pore materials with pore dimensions on a scale of tens of nanometers, and are thus classified as mesoporous materials. In this work, we show that the combination of NMR spectroscopy and chemical-shift selective magnetic resonance imaging (MRI) can resolve some of the important aspects of the structure of silica aerogels. The use of xenon as a gaseous probe in combination with spatially resolved NMR techniques is demonstrated to be a powerful, new approach for characterizing the average pore structure and steady-state spatial distributions of xenon atoms in different physicochemical environments. Furthermore, dynamic NMR magnetization transfer experiments and pulsed-field gradient (PFG) measurements have been used to characterize exchange processes and diffusive motion of xenon in samples at equilibrium. In particular, this new NMR approach offers unique information and insights into the nanoscopic pore structure and microscopic morphology of aerogels and the dynamical behavior of occluded adsorbates. MRI provides spatially resolved information on the nature of the flaw regions found in these materials. Pseudo-first-order rate constants for magnetization transfer among the bulk and occluded xenon phases indicate xenon-exchange rate constants on the order of 1 s-1 for specimens having volumes of 0.03 cm3. PFG diffusion measurements show evidence of anisotropic diffusion for xenon occluded within aerogels, with nominal self-diffusivity coefficients on the order of D= 10-3cm2/s.

  5. Hyperpolarized Xe-129 NMR Investigation of Ammonia Borane in Mesoporous Silica

    SciTech Connect (OSTI)

    Wang, Li Q.; Karkamkar, Abhijeet J.; Autrey, Thomas; Exarhos, Gregory J.

    2009-04-23

    Hyperpolarized (HP) 129Xe NMR was used for the first time to probe the porosity for nanophase ammonium borane (AB) infused in mesoporous silica (MCM). Variable temperature HP 129Xe NMR measurements have been systematically carried out on a series of AB:MCM materials with different AB loading. Three distinct types of pore environments are clearly evident: pristine mesopores; pores coated with AB inside the meso-channels, and inter-particle spacing formed from AB aggregates outside the meso-channels. We found similarly uniform coating of AB on mesoporous silica channels with 1:2 and 1:1 AB:MCM loading (ratio of weight percent). When the loading of AB to MCM is larger than 1:1, AB starts to aggregate outside the meso-channels. Further increases in loading (? 3:1) result in the formation of partially blocked meso-channels as a result of excessive AB loading. The detailed information obtained from this study on how supported AB resides in nanoporous channels and how it evolves with the increase of AB loading is helpful for rational design of novel materials with optimal hydrogen storage and release properties.

  6. Interfacial aggregation of a nonionic surfactant: Effect on the stability of silica suspensions

    SciTech Connect (OSTI)

    Giordano-Palmino, F.; Denoyel, R.; Rouquerol, J. . Centre de thermodynamique et Microcalorimetrie)

    1994-06-01

    Nonionic surfactants are in widespread use in technological applications such as flotation, detergency, suspension stabilization (paints, ceramic preparation, pharmaceuticals, cosmetics), and enhanced oil recovery. The adsorption of the nonionic surfactant TX 100 in two silica suspensions (Ludox HS40 and Syton W30) has been studied with the aim of relating the structure of the adsorbed layer to the stability of the suspension. First, a thermodynamic study based on the determination of adsorption isotherms and displacement enthalpies as a function of pH and solid/liquid ratio was carried out and lead to the conclusion that such a surfactant forms micelle-like aggregates on the silica surface. Then, a stability study based on visual observation, turbidimetry, and particle size determination (by photon correlation spectroscopy) was performed in order to determine the TX 100 concentration range in which flocculation occurs. Considering that the surface is covered with micelle-like aggregates in the flocculation range and that the [zeta]-potential (determined by microelectrophoresis) has varied only slightly at the onset of flocculation, it is concluded that the flocculation mechanism is a bridging of particles by surface micelles. This bridging of particles by aggregates similar in size and shape could be an explanation of the presence, in such systems, of optimum flocculation at half surface coverage.

  7. Formation of conical emission of supercontinuum during filamentation of femtosecond laser radiation in fused silica

    SciTech Connect (OSTI)

    Kandidov, V. P. Smetanina, E. O.; Dormidonov, A. E.; Kompanets, V. O.; Chekalin, S. V.

    2011-09-15

    The formation of conical emission of supercontinuum during filamentation of femtosecond laser pulses with central wavelengths in a wide range is studied experimentally, numerically, and analytically. The frequency-angular intensity distribution of the spectral components of conical emission is determined by the interference of supercontinuum emission in a filament of a femtosecond laser pulse. The interference of supercontinuum emission has a general character, exists at different regimes of group velocity dispersion, gives rise to the fine spectral structure after the pulse splitting into subpulses and the formation of a distributed supercontinuum source in an extended filament, and causes the decomposition of the continuous spectrum of conical emission into many high-contrast maxima after pulse refocusing in the filament. In spectroscopic studies with a tunable femtosecond radiation source based on a TOPAS parametric amplifier, we used an original scheme with a wedge fused silica sample. Numerical simulations have been performed using a system of equations of nonlinear-optical interaction of laser radiation under conditions of diffraction, wave nonstationarity, and material dispersion in fused silica. The analytic study is based on the interference model of formation of conical emission by supercontinuum sources moving in a filament.

  8. Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition – A facile method for encapsulation of diverse cell types in silica matrices

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Johnston, Robert; Rogelj, Snezna; Harper, Jason C.; Tartis, Michaelann

    2014-12-12

    In nature, cells perform a variety of complex functions such as sensing, catalysis, and energy conversion which hold great potential for biotechnological device construction. However, cellular sensitivity to ex vivo environments necessitates development of bio–nano interfaces which allow integration of cells into devices and maintain their desired functionality. In order to develop such an interface, the use of a novel Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition process for whole cell encapsulation in silica was explored. In SG-CViL, the high vapor pressure of tetramethyl orthosilicate (TMOS) is utilized to deliver silica into an aqueous medium, creating a silica sol. Cellsmore » are then mixed with the resulting silica sol, facilitating encapsulation of cells in silica while minimizing cell contact with the cytotoxic products of silica generating reactions (i.e. methanol), and reduce exposure of cells to compressive stresses induced from silica condensation reactions. Using SG-CVIL, Saccharomyces cerevisiae (S. cerevisiae) engineered with an inducible beta galactosidase system were encapsulated in silica solids and remained both viable and responsive 29 days post encapsulation. By tuning SG-CViL parameters, thin layer silica deposition on mammalian HeLa and U87 human cancer cells was also achieved. Furthermore, the ability to encapsulate various cell types in either a multi cell (S. cerevisiae) or a thin layer (HeLa and U87 cells) fashion shows the promise of SG-CViL as an encapsulation strategy for generating cell–silica constructs with diverse functions for incorporation into devices for sensing, bioelectronics, biocatalysis, and biofuel applications.« less

  9. Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition – A facile method for encapsulation of diverse cell types in silica matrices

    SciTech Connect (OSTI)

    Johnston, Robert; Rogelj, Snezna; Harper, Jason C.; Tartis, Michaelann

    2014-12-12

    In nature, cells perform a variety of complex functions such as sensing, catalysis, and energy conversion which hold great potential for biotechnological device construction. However, cellular sensitivity to ex vivo environments necessitates development of bio–nano interfaces which allow integration of cells into devices and maintain their desired functionality. In order to develop such an interface, the use of a novel Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition process for whole cell encapsulation in silica was explored. In SG-CViL, the high vapor pressure of tetramethyl orthosilicate (TMOS) is utilized to deliver silica into an aqueous medium, creating a silica sol. Cells are then mixed with the resulting silica sol, facilitating encapsulation of cells in silica while minimizing cell contact with the cytotoxic products of silica generating reactions (i.e. methanol), and reduce exposure of cells to compressive stresses induced from silica condensation reactions. Using SG-CVIL, Saccharomyces cerevisiae (S. cerevisiae) engineered with an inducible beta galactosidase system were encapsulated in silica solids and remained both viable and responsive 29 days post encapsulation. By tuning SG-CViL parameters, thin layer silica deposition on mammalian HeLa and U87 human cancer cells was also achieved. Furthermore, the ability to encapsulate various cell types in either a multi cell (S. cerevisiae) or a thin layer (HeLa and U87 cells) fashion shows the promise of SG-CViL as an encapsulation strategy for generating cell–silica constructs with diverse functions for incorporation into devices for sensing, bioelectronics, biocatalysis, and biofuel applications.

  10. U-Pb ages of secondary silica at Yucca Mountain, Nevada: implications for the paleohydrology of the unsaturated zone

    SciTech Connect (OSTI)

    Neymark, L.A.; Amelin, Y.; Paces, J.B.; Peterman, Z.E.

    2002-06-01

    This paper reports the results of analyses of uranium, thorium, and lead in layers of opal and chalcedony from individual mm- to cm-thick calcite and silica coatings at Yucca Mountain, Nevada, USA, a site that is being evaluated for a potential high-level nuclear waste repository.

  11. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    SciTech Connect (OSTI)

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L

    2010-02-23

    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical probability of damage initiation at 12 J/cm{sup 2} of an ensemble of scratches decreased from {approx}100 mm{sup -1} of scratch length to {approx}0.001 mm{sup -1}.

  12. Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

    SciTech Connect (OSTI)

    Khezri, Khezrollah; Roghani-Mamaqani, Hossein

    2014-11-15

    Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric analysis shows that thermal stability of the nanocomposites increases by adding nanoparticles content. Decrease of glass transition temperature is also demonstrated by the addition of 3 wt% of silica nanoparticles according to the differential scanning calorimetry results.

  13. Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

    DOE Patents [OSTI]

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

    2015-07-14

    Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

  14. Reduction of damage initiation density in fused silica optics via UV laser conditioning

    DOE Patents [OSTI]

    Peterson, John E.; Maricle, Stephen M.; Brusasco, Raymond M.; Penetrante, Bernardino M.

    2004-03-16

    The present invention provides a method for reducing the density of sites on the surface of fused silica optics that are prone to the initiation of laser-induced damage, resulting in optics which have far fewer catastrophic defects and are better capable of resisting optical deterioration upon exposure for a long period of time to a high-power laser beam having a wavelength of about 360 nm or less. The initiation of laser-induced damage is reduced by conditioning the optic at low fluences below levels that normally lead to catastrophic growth of damage. When the optic is then irradiated at its high fluence design limit, the concentration of catastrophic damage sites that form on the surface of the optic is greatly reduced.

  15. Liquidsolid phase transition of hydrogen and deuterium in silica aerogel

    SciTech Connect (OSTI)

    Van Cleve, E.; Worsley, M. A.; Kucheyev, S. O.

    2014-10-28

    Behavior of hydrogen isotopes confined in disordered low-density nanoporous solids remains essentially unknown. Here, we use relaxation calorimetry to study freezing and melting of H{sub 2} and D{sub 2} in an ?85%-porous base-catalyzed silica aerogel. We find that liquidsolid transition temperatures of both isotopes inside the aerogel are depressed. The phase transition takes place over a wide temperature range of ?4?K and non-trivially depends on the liquid filling fraction, reflecting the broad pore size distribution in the aerogel. Undercooling is observed for both H{sub 2} and D{sub 2} confined inside the aerogel monolith. Results for H{sub 2} and D{sub 2} are extrapolated to tritium-containing hydrogens with the quantum law of corresponding states.

  16. Sealing 304L to lithia-alumina-silica (LAS) glass-ceramics

    SciTech Connect (OSTI)

    Moddeman, W.E.; Pence, R.E.; Massey, R.T.; Cassidy, R.T.; Kramer, D.P.

    1989-12-31

    The formation of a crack-free between 300 series stainless steel and a glass-ceramic is difficult owing to the high coefficients of thermal expansion of the stainless steels. Lithia-alumina-silica (LAS) glass-ceramics were successfully developed and sealed to 304L stainless steel. These crack-free seals were fabricated by two techniques: by adjusting the parent glass composition (reducing the Al{sub 2}O{sub 3} content), or by adjusting the sealing/crystallization cycle. All seals were hermetic, with leak rates < 10{sup -8} cc/sec STP helium. CTE and alloy yield strengths are given which show the feasibility of using these materials to make feedthroughs, pyrotechnic components, etc. Metallography, SEM, and wavelength dispersive spectroscopy show the quality and integrity of the glass-ceramic/stainless steel interface. These data are compared to those on the Inconel 718/LAS-glass seal system.

  17. Measurement of optical scattered power from laser-induced shallow pits on silica

    SciTech Connect (OSTI)

    Feigenbaum, Eyal; Nielsen, Norman; Matthews, Manyalibo J.

    2015-10-01

    We describe a model for far-field scattered power and irradiance by a silica glass slab with a shallow-pitted exit surface and is experimentally validated. The comparison to the model is performed using a precisely micromachined ensemble of ~11 μm wide laser ablated shallow pits producing 1% of the incident beam scatter in a 10 mrad angle. This series of samples with damage initiations and laser-induced shallow pits resulting from 351 nm, 5 ns pulsed laser cleaning of metal microparticles at different fluences between 2 J/cm2 and 11 J/cm2 are characterized as well and found in good agreement with model predictions.

  18. Transparent ultralow-density silica aerogels prepared by a two-step sol-gel process

    SciTech Connect (OSTI)

    Tillotson, T.M.; Hrubesh, L.W.

    1991-09-01

    Conventional silica sol-gel chemistry is limited for the production of transparent ultralow-density aerogels because (1) gelation is either slow or unachievable, and (2) even when gelation is achieved, the large pore sizes result in loss of transparency for aerogels <.020 g/cc. We have developed a two-step sol-gel process that circumvents the limitations of the conventional process and allows the formation of ultralow-density gels in a matter of hours. we have found that the gel time is dependent on the catalyst concentration. After supercritical extraction, the aerogels are transparent, uncracked tiles with densities as low as .003 g/cc. 6 figs., 11 refs.

  19. Determination of external surface area of ultrahigh silica zeolites by the paramagnetic net methods

    SciTech Connect (OSTI)

    Lunina, E.V.; Lebedeva, O.E.; Motina, A.D.; Lobza, G.V.; Latysheva, L.E.; Chenets, V.V.

    1988-02-01

    We propose a new method for determining the surface area of large-pore adsorbents which do not contain paramagnetic impurities: the paramagnetic net method. The method is based on determining the average distances between paramagnetic centers which are randomly and uniformly distributed over the adsorbent surface. As the paramagnetic probe, we use the stable nitroxide radical 2,2,6,6-tetramethyl-piperidine-1-oxyl. We show that the method is applicable to measurement of the external surface area of crystallites of ultrahigh silica zeolites. Decationation leads to its increase without an increase in the contribution of the amorphous phase. This effect is explained by dispersal of concretions of small crystallites during ion exchange.

  20. Density hysteresis of heavy water confined in a nanoporous silica matrix

    SciTech Connect (OSTI)

    Zhang, Yang; Faraone, Antonio; Kamitakahara, William; Liu, Kao-Hsiang; Mou, Chung-Yuan; Leao, Juscelino B; Chang, Sung C; Chen, Sow-hsin H

    2011-01-01

    A neutron scattering technique was developed to measure the density of heavy water confined in a nanoporous silica matrix in a temperature-pressure range, from 300 to 130 K and from 1 to 2,900 bars, where bulk water will crystalize. We observed a prominent hysteresis phenomenon in the measured density profiles between warming and cooling scans above 1,000 bars. We inter- pret this hysteresis phenomenon as support (although not a proof) of the hypothetical existence of a first-order liquid liquid phase transition of water that would exist in the macroscopic system if crystallization could be avoided in the relevant phase region. Moreover, the density data we obtained for the confined heavy water under these conditions are valuable to large communities in biology and earth and planetary sciences interested in phenomena in which nanometer-sized water layers are involved.

  1. Measurement of optical scattered power from laser-induced shallow pits on silica

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Feigenbaum, Eyal; Nielsen, Norman; Matthews, Manyalibo J.

    2015-10-01

    We describe a model for far-field scattered power and irradiance by a silica glass slab with a shallow-pitted exit surface and is experimentally validated. The comparison to the model is performed using a precisely micromachined ensemble of ~11 μm wide laser ablated shallow pits producing 1% of the incident beam scatter in a 10 mrad angle. This series of samples with damage initiations and laser-induced shallow pits resulting from 351 nm, 5 ns pulsed laser cleaning of metal microparticles at different fluences between 2 J/cm2 and 11 J/cm2 are characterized as well and found in good agreement with model predictions.

  2. Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

    DOE Patents [OSTI]

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

    2015-08-11

    Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

  3. Photoresponsive Release from Azobenzene-Modified Single Cubic Crystal NaCl/Silica Particles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jiang, Xingmao; Liu, Nanguo; Assink, Roger A.; Jiang, Yingbing; Brinker, C. Jeffrey

    2011-01-01

    Azobenzene ligands were uniformly anchored to the pore surfaces of nanoporous silica particles with single crystal NaCl using 4-(3-triethoxysilylpropylureido)azobenzene (TSUA). The functionalization delayed the release of NaCl significantly. The modified particles demonstrated a photocontrolled release by trans/cis isomerization of azobenzene moieties. The addition of amphiphilic solvents, propylene glycol (PG), propylene glycol propyl ether (PGPE), and dipropylene glycol propyl ether (DPGPE) delayed the release in water, although the wetting behavior was improved and the delay is the most for the block molecules with the longest carbon chain. The speedup by UV irradiation suggests a strong dependence of diffusion on the switchablemore » pore size. TGA, XRD, FTIR, and NMR techniques were used to characterize the structures.« less

  4. Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; Xu, Huifang; Rathod, Shailendra; Shah, Pratik; Brinker, C. Jeffrey

    2011-01-01

    Ceriumore » m (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0 × 10 − 14  m 2 s for Ce 3+ compared to 2.5 × 10 − 13  m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.« less

  5. Laser induced diffusion of ion-implanted bismuth in fused silica

    SciTech Connect (OSTI)

    Park, S.Y.; Weeks, R.A.; Zuhr, R.A.

    1994-12-31

    The near surface regions of optical grade fused silica discs (Spectrosil A) were modified by implantation with bismuth ions at 160 and 320 keV and at room temperature. The glasses implanted with a nominal dose of 6 {times} l0{sup 16} Bi{sup 2+} ions/cm{sup 2} were subsequently annealed with a 5 eV KrF pulsed excimer laser and by a furnace in oxygen atmosphere. Rutherford backscattering and optical absorption were measured before and after the anneals. Backscattering profiles after laser anneal showed shifts of the profiles toward the surface with decrease in retained dose. We attribute the diffusion of bismuth to Soret effect. Profiles of furnace annealed samples showed that the diffusion was both toward and away from the surface.

  6. Highly fluorescent silver nanoclusters in alumina-silica composite optical fiber

    SciTech Connect (OSTI)

    Halder, A.; Chattopadhyay, R.; Majumder, S.; Paul, M. C.; Das, S.; Bhadra, S. K.; Bysakh, S.; Unnikrishnan, M.

    2015-01-05

    An efficient visible fluorescent optical fiber embedded with silver nanoclusters (Ag-NCs) having size ∼1 nm, uniformly distributed in alumina-silica composite core glass, is reported. Fibers are fabricated in a repetitive controlled way through modified chemical vapour deposition process associated with solution doping technique. Fibers are drawn from the transparent preforms by conventional fiber drawing process. Structural characteristics of the doped fibers are studied using transmission electron microscopy and electron probe micro analysis. The oxidation state of Ag within Ag-NCs is investigated by X-ray photo electron spectroscopy. The observed significant fluorescence of the metal clusters in fabricated fibers is correlated with electronic model. The experimentally observed size dependent absorption of the metal clusters in fabricated fibers is explained with the help of reported results calculated by ab-initio density functional theory. These optical fibers may open up an opportunity of realizing tunable wavelength fiber laser without the help of rare earth elements.

  7. Rare-earth elements in hot brines (165 to 190 degree C) from the Salton Sea geothermal field

    SciTech Connect (OSTI)

    Lepel, E.A.; Laul, J.C.; Smith, M.R.

    1988-01-01

    Rare-earth element (REE) concentrations are important indicators for revealing various chemical fractionation processes (water/rock interactions) and source region geochemistry. Since the REE patterns are characteristic of geologic materials (basalt, granite, shale, sediments, etc.) and minerals (K-feldspar, calcite, illite, epidote, etc.), their study in geothermal fluids may serve as a geothermometer. The REE study may also enable us to address the issue of groundwater mixing. In addition, the behavior of the REE can serve as analogs of the actinides in radioactive waste (e.g., neodymium is an analog of americium and curium). In this paper, the authors port the REE data for a Salton Sea Geothermal Field (SSGF) brine (two aliquots: port 4 at 165{degree}C and port 5 at 190{degree}C) and six associated core samples.

  8. Carbonyl sulphide (COS) in geothermal fluids; An example from the Larderello field (Italy)

    SciTech Connect (OSTI)

    Chiodini, G. ); Cioni, R.; Raco, B. ); Scandiffio, G. )

    1991-01-01

    This paper reports that the carbonyl sulphide (COS) content in the fluids of 12 wells in the Larderello geothermal field ranges from 0.005 to 0.1 {mu}m mol/mol. Measured data are comparable with the theoretical concentrations, considering a homogeneous gas phase at the temperature and pressure conditions of the reservoir. However, the low temperature dependence of equilibrium constants of reactions involving COS prevents us from using them as geothermometers. On the contrary, P{sub CO{sub 2}} estimates in the gas equilibration zone can be inferred from the H{sub 2}S/COS ratio. The calculated CO{sub 2} partial pressures are comparable with those estimated by means of the H{sub 2}/CO ratio.

  9. Colorado's hydrothermal resource base: an assessment

    SciTech Connect (OSTI)

    Pearl, R.H.

    1981-01-01

    As part of its effort to more accurately describe the nations geothrmal resource potential, the US Department of Energy/Division of Geothermal Energy contracted with the Colorado Geological survey to appraise the hydrothermal (hot water) geothermal resources of Colorado. Part of this effort required that the amount of energy that could possibly be contained in the various hydrothermal systems in Colorado be estimated. The findings of that assessment are presented. To make these estimates the geothermometer reservoir temperatures estimated by Barrett and Pearl (1978) were used. In addition, the possible reservoir size and extent were estimated and used. This assessment shows that the total energy content of the thermal systems in Colorado could range from 4.872 x 10{sup 15} BTU's to 13.2386 x 10{sup 15} BTU's.

  10. Improved Geothermometry Through Multivariate Reaction-path Modeling and Evaluation of Geomicrobiological Influences on Geochemical Temperature Indicators: Final Report

    SciTech Connect (OSTI)

    Mattson, Earl; Smith, Robert; Fujita, Yoshiko; McLing, Travis; Neupane, Ghanashyam; Palmer, Carl; Reed, David; Thompson, Vicki

    2015-03-01

    The project was aimed at demonstrating that the geothermometric predictions can be improved through the application of multi-element reaction path modeling that accounts for lithologic and tectonic settings, while also accounting for biological influences on geochemical temperature indicators. The limited utilization of chemical signatures by individual traditional geothermometer in the development of reservoir temperature estimates may have been constraining their reliability for evaluation of potential geothermal resources. This project, however, was intended to build a geothermometry tool which can integrate multi-component reaction path modeling with process-optimization capability that can be applied to dilute, low-temperature water samples to consistently predict reservoir temperature within ±30 °C. The project was also intended to evaluate the extent to which microbiological processes can modulate the geochemical signals in some thermal waters and influence the geothermometric predictions.

  11. Effects of biogenic silica on acoustic and physical properties of clay-rich marine sediments

    SciTech Connect (OSTI)

    Tribble, J.S.; Mackenzie, F.T.; Urmos, J.; O'Brien, D.K.; Manghnani, M.H. )

    1992-06-01

    The physical properties of marine sediments are influenced by compaction and diagenesis during burial. Changes in mineralogy, chemistry, density, porosity, and microfabric all affect a sediment's acoustic and electrical properties. Sediments from the Japan Trench illustrate the dependence of physical properties on biogenic silica content. Increased opal-A content is correlated with increased porosity and decreased grain density and compressional velocity. Variations with depth in opal-A concentration are therefore reflected in highly variable and, at times, inverse velocity-depth gradients. The diagenetic conversion of opal-A to opal-CT and finally to quartz was investigated at a site in the San Miguel Gap, California. Distinct changes in microfabric, particularly in the porosity distribution, accompany the diagenetic reactions and contribute to a sharp velocity discontinuity at the depth of the opal-A to opal-CT conversion. Evaluation of this reaction at several sites indicates a systematic dependence on temperature and age in clay-rich and moderately siliceous sediments. In ocean margin regions, sediments are buried rapidly, and opal-A may be converted to opal-CT in less than 10 m.y. Temperatures of conversion range from 30{degree} to 50{degree}C. Much longer times (>40 m.y.) are required to complete the conversion in open ocean deposits which are exposed to temperatures less than 15{degree}C. In the absence of silica diagenesis, velocity-depth gradients of most clay-rich and moderately siliceous sediments fall in the narrow range of 0.15 to 0.25 km/s/km which brackets the gradient (0.18 km/s/km) determined for a type pelagic clay section. Relationships such as these can be useful in unraveling the history of a sediment sequence, including the evolution with time of reservoir properties and seismic signatures.

  12. Does elevated CO2 alter silica uptake in trees?

    SciTech Connect (OSTI)

    Fulweiler, Robinson W.; Maguire, Timothy J.; Carey, Joanna C.; Finzi, Adrien C.

    2015-01-13

    Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO2 fertilization, longterm free-air CO2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine), and five hardwood species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.

  13. Geothermal prospecting by geochemical methods on natural gas and water discharges in the Vulsini Mts Volcanic District (Central Italy)

    SciTech Connect (OSTI)

    Duchi, V.; Minissale, A.A.; Ortino, S.; Romani, L.

    1987-01-01

    The Latera and Torre Alfina geothermal fields were discovered in the Vulsini Mts district (central Italy) in the 70s. The fluid produced by the two geothermal systems is a high rhoCO/sub 2/(around 7 MPa) sodium chloride solution (T.D.S. is 9200 ppm at Latera and 7800 at Torre Alfina), with high SiO/sub 2/ and H/sub 3/BO/sub 3/ contents. The fluid temperature taken at well bottom is about 155/sup 0/C at Torre Alfina, whereas at Latera it ranges from 200 to over 350/sup 0/C. In spite of these temperatures, recorded in producing wells, previous geochemical prospectings using geothermometers in natural thermal manifestations had predicted temperatures no higher than 140/sup 0/C in all the Vulsini district. This contrasting feature between real temperatures and those evaluated during prospecting is caused by the fast circulation of large amounts of meteoric waters in the aquifer located in the shallow parts of the carbonate reservoir formations, and by the short interaction between the latter and the deep geothermal fluids. In the present study a new geochemical survey on thermal and cold springs, stream samples, as well as natural gas emissions has been carried out. A critical review of the main geothermometers, some considerations about the hydraulic behavior of the reservoir formations, and the cross comparison between NH/sub 4//sup +//B ratio, rhoCO/sub 2/ and SiO/sub 2/ content in both cold and thermal waters, have led to the conclusion that in the Vulsini Mts there are no shallow anomalous areas apart from those already discovered at Latera and Torre Alfina. The present method could be successfully applied in other geothermal systems, where the potential reservoir is represented by carbonate formations.

  14. U-Pb Ages of Secondary Silica at Yucca Mountain, Nevada: Implications for the Paleohydrology of the Unsaturated Zone

    SciTech Connect (OSTI)

    L.A. Neymark; Y. Amelin; J.B. Paces; Z.E. Peterman

    2001-08-20

    U, Th, and Pb isotopes were analyzed in layers of opal and chalcedony from individual millimeter- to centimeter-thick calcite and silica coatings at Yucca Mountain, Nevada, USA, a site that is being evaluated for a potential high-level nuclear waste repository. These calcite and silica coatings on fractures and in lithophysal cavities in Miocene-age tuffs in the unsaturated zone (UZ) precipitated from descending water and record a long history of percolation through the UZ. Opal and chalcedony have high concentrations of U (10 to 780 ppm) and low concentrations of common Pb as indicated by large values of {sup 206}Pb/{sup 204}Pb (up to 53,806), thus making them suitable for U-Pb age determinations. Interpretations of U-Pb isotopes in opal samples at Yucca Mountain are complicated by the incorporation of excess {sup 234}U at the time of mineral formation, resulting in reverse discordance of U-Pb ages. However, the {sup 207}Pb/{sup 235}U ages are much less affected by deviation from initial secular equilibrium and provide reliable ages of most silica deposits between 0.6 and 9.8 Ma. For chalcedony subsamples showing normal age discordance, these ages may represent minimum times of deposition. Typically, {sup 207}Pb/{sup 235}U ages are consistent with the microstratigraphy in the mineral coating samples, such that the youngest ages are for subsamples from outer layers, intermediate ages are from inner layers, and oldest ages are from innermost layers. {sup 234}U and {sup 230}Th in most silica layers deeper in the coatings are in secular equilibrium with {sup 238}U, which is consistent with their old age and closed system behavior during the past 0.5 m.y. U-Pb ages for subsamples of silica layers from different microstratigraphic positions in individual calcite and silica coating samples collected from lithophysal cavities in the welded part of the Topopah Spring Tuff yield slow long-term average depositional rates of 1 to 5 mm/m.y. These data imply that the deeper parts of the UZ at Yucca Mountain maintained long-term hydrologic stability over the past 10 m.y. despite significant climate variations. U-Pb ages for subsamples of silica layers from different microstratigraphic positions in individual calcite and silica coating samples collected from fractures in the welded part of the overlying Tiva Canyon Tuff indicate larger long-term average depositional rates up to 23 mm/m.y. and an absence of recently deposited materials (ages of outermost layers are 3-5 Ma). These differences between the characteristics of the coatings for samples from the shallower and deeper parts of the UZ may indicate that the nonwelded tuffs (PTn), located between the welded parts of the Tiva Canyon and Topopah Spring Tuffs, play an important role in moderating UZ flow.

  15. A comparative study of inverted-opal titania photonic crystals made from polymer and silica colloidal crystal templates

    SciTech Connect (OSTI)

    Kuai, S.-L.; Truong, V.-V.; Hache, Alain; Hu, X.-F.

    2004-12-01

    Photonic crystals with an inverted-opal structure using polymer and silica colloidal crystal templates were prepared and compared. We show that the behaviors of the template during the removal process and heat treatment are determinant factors on the crystal formation. While both templates result in ordered macroporous structures, the optical quality in each case is quite different. The removal of the polymer template by sintering causes a large shrinkage of the inverted framework and produces a high density of cracks in the sample. With a silica template, sintering actually improves the quality of the inverted structure by enhancing the template's mechanical stability, helping increase the filling fraction, and consolidating the titania framework. The role of the other important factors such as preheating and multiple infiltrations is also investigated.

  16. Mesoporous Silica Films with Long-Range Order Prepared from Strongly Segregated Block Copolymer/Homopolymer Blend Templates

    SciTech Connect (OSTI)

    Tirumala, Vijay R.; Pai, Rajaram A.; Agarwal, Sumit; Testa, Jason J.; Bhatnagar, Gaurav; Romang, Alvin H.; Chandler, Curran; Gorman, Brian P.; Jones, Ronald L.; Lin, Eric K.; Watkins, James J.

    2008-06-30

    Well-ordered mesoporous silica films were prepared by infusion and selective condensation of Si alkoxides within preorganized block copolymer/homopolymer blend templates using supercritical CO{sub 2} as the delivery medium. The morphologies of the mesoporous silica films reflect significant improvements in the strength of segregation and long-range order of template blends of poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymers with selectively associating homopolymers such as poly(acrylic acid) or poly(4-hydroxystyrene) prior as compared to templates comprised of the neat copolymer. Control over film porosity, pore ordering, and morphology of the films is achieved through simple variations in the homopolymer concentration. The films were characterized using X-ray reflectivity, small-angle X-ray scattering, and transmission electron microscopy.

  17. Atomistic Simulations of Displacement Cascades in Fused Silica: It is Compared with Different Concentration of H in the Bulk

    SciTech Connect (OSTI)

    Mota, Fernando; Perlado, Jose Manuel; Caturla, Maria Jose; Ibarra, Angel; Molla, Joaquin

    2008-07-01

    Amorphous Silica is one of candidate materials for both final focusing optics of lasers for NIF and future inertial fusion reactors and diagnostics of the Safety and Control Systems of the ITER machine as well as DEMO magnetic fusion reactors. In operation, these materials will be exposed to high neutron irradiation fluxes and it can result in point defect and vary the optical absorption, that is, degradation of the optical properties. In this paper we present molecular dynamic simulation of displacement cascade due to energetic recoils in amorphous silica without hydrogen atoms and with 1% of hydrogen atoms trying to identify defects formation. We have made a statistics of the different kind of defects at different energy of primary knock-on atoms (PKA). The range of studied PKA energies are from 400 eV to 3.5 keV and it is made to both component of this material Silicon and Oxygen. (authors)

  18. Immobilization of cellulase on a silica gel substrate modified using a 3-APTES self-assembled monolayer

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Dezhi; Hegab, Hisham E.; Lvov, Yuri; Snow, L. Dale; Palmer, James

    2016-01-20

    Cellulase was immobilized onto silica gel surfaces pretreated with (3-aminopropyl) triethoxy-silane (3-APTES), and glutaraldehyde (GA) was used as a cross-linker. A carboxymethyl cellulose sodium salt (CMC) solution was used for activity experiments. Protein assay was performed to determine the mass immobilized and compare with free enzyme. Cellulase was successfully demonstrated to be immobilized on the modified silica gel surface, and no detectable amount of enzyme was stripped off during the hydrolysis of the CMC solution. The specific activity of the immobilized cellulase is 7 ± 2 % compared to the similar amount of free cellulase. Significant activity over multiple reusesmore » was observed. The seventh batch achieved 82 % activity of the initial batch, and the fifteenth batch retained 31 %. Lastly, it was observed that the immobilized cellulase retained 48 % of its initial activity after 4 days, and 22 % even after 14 days.« less

  19. BIMETALLIC NANOCATALYSTS IN MESOPOROUS SILICA FOR HYDROGEN PRODUCTION FROM COAL-DERIVED FUELS

    SciTech Connect (OSTI)

    Kuila, Debasish; Ilias, Shamsuddin

    2013-02-13

    In steam reforming reactions (SRRs) of alkanes and alcohols to produce H{sub 2}, noble metals such as platinum (Pt) and palladium (Pd) are extensively used as catalyst. These metals are expensive; so, to reduce noble-metal loading, bi-metallic nanocatalysts containing non-noble metals in MCM-41 (Mobil Composition of Material No. 41, a mesoporous material) as a support material with high-surface area were synthesized using one-pot hydrothermal procedure with a surfactant such as cetyltrimethylammonium bromide (CTAB) as a template. Bi-metallic nanocatalysts of Pd-Ni and Pd-Co with varying metal loadings in MCM-41 were characterized by x-ray diffraction (XRD), N{sub 2} adsorption, and Transmission electron microscopy (TEM) techniques. The BET surface area of MCM-41 (~1000 m{sup 2}/g) containing metal nanoparticles decreases with the increase in metal loading. The FTIR studies confirm strong interaction between Si-O-M (M = Pd, Ni, Co) units and successful inclusion of metal into the mesoporous silica matrix. The catalyst activities were examined in steam reforming of methanol (SRM) reactions to produce hydrogen. Reference tests using catalysts containing individual metals (Pd, Ni and Co) were also performed to investigate the effect of the bimetallic system on the catalytic behavior in the SRM reactions. The bimetallic system remarkably improves the hydrogen selectivity, methanol conversion and stability of the catalyst. The results are consistent with a synergistic behavior for the Pd-Ni-bimetallic system. The performance, durability and thermal stability of the Pd-Ni/MCM-41 and Pd-Co/MCM-41 suggest that these materials may be promising catalysts for hydrogen production from biofuels. A part of this work for synthesis and characterization of Pd-Ni-MCM-41 and its activity for SRM reactions has been published (“Development of Mesoporous Silica Encapsulated Pd-Ni Nanocatalyst for Hydrogen Production” in “Production and Purification of Ultraclean Transportation Fuels”; Hu, Y., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2011.)

  20. Silane Modification of Glass and Silica Surfaces to Obtain Equally Oil-Wet Surfaces in Glass-Covered Silicon Micromodel Applications

    SciTech Connect (OSTI)

    Grate, Jay W.; Warner, Marvin G.; Pittman, Jonathan W.; Dehoff, Karl J.; Wietsma, Thomas W.; Zhang, Changyong; Oostrom, Martinus

    2013-08-05

    The wettability of silicon and glass surfaces can be modified by silanization. However, similar treatments of glass and silica surfaces using the same silane do not necessarily yield the same wettability as determined by the oil-water contact angle. In this technical note, surface cleaning pretreatments were investigated to determine conditions that would yield oil-wet surfaces on glass with similar wettability to silica surfaces treated with the same silane, and both air-water and oil-water contact angles were determined. Air-water contact angles were less sensitive to differences between silanized silica and glass surfaces, often yielding similar values while the oil-water contact angles were quite different. Borosilicate glass surfaces cleaned with standard cleaning solution 1 (SC1) yield intermediate-wet surfaces when silanized with hexamethyldisilazane, while the same cleaning and silanization yields oil-wet surfaces on silica. However, cleaning glass in boiling concentrated nitric acid creates a surface that can be silanized to obtain oil-wet surfaces using HDMS. Moreover, this method is effective on glass with prior thermal treatment at an elevated temperature of 400oC. In this way, silica and glass can be silanized to obtain equally oil-wet surfaces using HMDS. It is demonstrated that pretreatment and silanization is feasible in silicon-silica/glass micromodels previously assembled by anodic bonding, and that the change in wettability has a significant observable effect on immiscisble fluid displacements in the pore network.

  1. Formation mechanisms of precursors of radiation-induced color centers during fabrication of silica optical fiber preform

    SciTech Connect (OSTI)

    Tomashuk, A. L.; Zabezhailov, M. O.

    2011-04-15

    Samples in the form of transverse slices of rods and optical fiber preforms made from the high-hydroxyl KU-1 and low-hydroxyl KS-4V silica by the plasma outside deposition (POD) method are {gamma}-irradiated to a dose of {approx}1 MGy (SiO{sub 2}). Next, the radial dependences of the radiation-induced nonbridging oxygen hole center (NBOHC) and E'-center (three-coordinated silicon) in the samples are constructed by measuring the amplitudes of their 4.8 and 5.8 eV absorption bands, respectively. Based on the analysis of these radial dependences and considering the temperature and duration of the preirradiation heat treatment of the rods and preforms at the POD-installation, we determine the ratio of the oscillator strengths of the above bands and the microscopic thermoinduced processes occurring during preform fabrication and producing precursors of the radiation-induced NBOHC and E'-center. These processes are found to be associated with the escape of either H{sub 2} or H{sub 2}O from neighboring hydroxyl groups, and, therefore, can occur in high-hydroxyl silica only. It is concluded that enhancement of the radiation resistance of high-hydroxyl silica optical fibers requires decreasing the temperature and duration of the preform fabrication process, in particular, changing from the POD-technology to the low-temperature plasmachemical vapor deposition (PCVD) or surface PCVD (SPCVD)-technology.

  2. Shock-induced irreversible transition from {alpha}-quartz to CaCl{sub 2}-like silica

    SciTech Connect (OSTI)

    Berterretche, P.; Resseguier, T. de; Hallouin, M.; Petitet, J. P.

    2004-10-15

    Previous analyses of quartz samples recovered after being submitted to laser shocks of very short duration (nanosecond order) have shown the presence of CaCl{sub 2}-like silica [T. de Resseguier, P. Berterretche, M. Hallouin, and J. P. Petitet, J. Appl. Phys. 94, 2123 (2003)]. To date, this transition has never been observed under shocks of longer duration (microsecond order) generated by explosives or plate impacts. While this phase is produced from stishovite under static compression at very high pressure (above 50 GPa) and disappears on pressure release, it is observed after low pressure laser shocks (below 5 GPa) and it is quenched to ambient conditions. The origins of these differences are still unclear. This paper presents complementary laser shock experiments involving setups to provide additional information on the influence of various shock parameters. The results suggest a direct transition from {alpha}-quartz to CaCl{sub 2}-type silica following a diffusionless mechanism involving high shear strains. They also show the presence of vitreous silica characterized by an 'organized' ringlike structure, and we propose that this amorphous phase is an intermediate structure between the quartz lattice and grains of the high-pressure phase.

  3. The Role of Non-Bonded Interactions in the Conformational Dynamics of Organophosphorous Hydrolase Adsorbed onto Functionalized Mesoporous Silica Surfaces

    SciTech Connect (OSTI)

    Gomes, Diego Enry B.; Lins, Roberto D.; Pascutti, Pedro G.; Lei, Chenghong; Soares, Thereza A.

    2010-01-14

    The enzyme organophosphorous hydrolase (OPH) catalyzes the hydrolysis of a wide variety of organophosphorous compounds with high catalytic efficiency and broad substrate specificity. The immobilization of OPH in functionalized mesoporous silica surfaces increases significantly its catalytic specific activity compared to the enzyme in solution with important applications for the detection and decontamination of insecticides and chemical warfare agents. Experimental measurements of immobilization efficiency as function of the charge and coverage percentage of different functional groups have been interpreted as electrostatic forces being the predominant interactions underlying the adsorption of OPH onto functionalized mesoporous silica surfaces. Explicit solvent molecular dynamics simulations have been performed for OPH in bulk solution and adsorbed onto two distinct interaction potential models of the mesoporous silica functional groups in order to investigate the relative contributions of non-bonded interactions to the conformational dynamics and adsorption of the protein. Our results support the conclusion that while electrostatic interactions are responsible for the specific binding of OPH to the FMS surface, van der Waals forces are detrimental for enhanced interfacial adhesion. Key-words: molecular dynamics simulations; bacterial phosphotriesterase; conformational changes; confined environments; coarse-grain and atomistic models; silanol molecular model.

  4. Silica phase changes: Diagenetic agent for oil entrapment, Lost Hills field, California

    SciTech Connect (OSTI)

    Julander, D.R.; Szymanski, D.L. )

    1991-02-01

    The siliceous shales of the Monterey Group are the primary development target at Lost Hills. Silica phase changes have influenced the distribution and entrapment of hydrocarbons. With increasing temperature, opal A phase diatomite is converted to opal CT and finally quartz phase rock. All phases are low in permeability. The opal A diatomite is characteristically high in oil saturation and productive saturation. Productivity from this phase is dependent on structural position and fieldwide variations in oil viscosity and biodegradation. The deeper chert reservoir coincides with the opal CT to quartz phase transition. Porosity is again reduced in this transition, but saturations in the quartz phase rocks increase. Tests in the chert reservoir indicate a single, low-permeability system, suggesting the importance of matric contribution. resistivity and porosity in the diatomite, and resistivity and velocity in the chert, are the physical properties which best reflect saturation. Methods exploiting these properties (FMS, BHTV, borehole, and surface shear wave studies) should be helpful in further characterizing the reservoirs and identifying future pay.

  5. Microstructural characterization of low-density foams. [Silica, resorcinol/formaldehyde, cellulose/acetate

    SciTech Connect (OSTI)

    Price, C.W.

    1988-01-01

    Low-density foams (of the order 0.1 g/cm/sup 3/) synthesized from silica aerogel, resorcinol/formaldehyde, and cellulose acetate have fine, delicate microstructures that are extremely difficult to characterize. Improved low-voltage resolution of an SEM equipped with a field-emission gun (FESEM) does permit these materials to be examined directly without coating and at sufficient magnification to reveal the microstructures. Light coatings applied by ion-beam deposition can stabilize the specimens to some extent and reduce electron charging without seriously altering the microstructure, but coatings applied by conventional techniques usually obliterate these microstructures. Transmission electron microscopy (TEM) is required to provide unambiguous microstructural interpretations. However, TEM examinations of these materials can be severely restricted by specimen preparation difficulties and electron-beam damage, and considerable care must be taken to ensure that reasonably accurate TEM results have been obtained. This work demonstrates that low-voltage FESEM analyses can be used to characterize microstructures in these foams, but TEM analyses are required to confirm the FESEM analyses and perform quantitative measurements. 19 refs., 11 figs.

  6. Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces

    SciTech Connect (OSTI)

    Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L

    2008-10-30

    Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.

  7. Structure and chemistry of sol-gel derived transparent silica aerogel

    SciTech Connect (OSTI)

    Tewari, P.H.; Lofftus, K.D.; Hunt, A.J.

    1985-02-01

    Transparent silica aerogels are being studied because of their excellent thermal insulation properties for window glazing materials. The chemistry of the base catalyzed Si(OC/sub 2/H/sub 5/)/sub 4/ sol-gel process to produce transparent aerogels is presented. The results of a factorial design set of experiments are discussed in which five process parameters are simultaneously varied. The goal of these experiments was to optimize the process conditions and to analyze the importance of various parameters in improving the properties of the aerogel. A novel technique of ambient temperature supercritical drying of alcogels is described. In this process, supercritical drying occurs at less than or equal to40/sup 0/C instead of at greater than or equal to270/sup 0/C and greater than or equal to1700 PSI (12 MPa), by substituting CO/sub 2/ for alcohol in the alcogel. The time of drying is reduced from 2 to 3 days to 8 to 10 hours. It is shown that light scattering, microstructural properties and other characteristics of aerogels produced by this process and by the high temperature supercritical drying are similar.

  8. Dynamics of femtosecond laser absorption of fused silica in the ablation regime

    SciTech Connect (OSTI)

    Lebugle, M. Sanner, N.; Varkentina, N.; Sentis, M.; Utéza, O.

    2014-08-14

    We investigate the ultrafast absorption dynamics of fused silica irradiated by a single 500 fs laser pulse in the context of micromachining applications. A 60-fs-resolution pump-probe experiment that measures the reflectivity and transmissivity of the target under excitation is developed to reveal the evolution of plasma absorption. Above the ablation threshold, an overcritical plasma with highly non-equilibrium conditions is evidenced in a thin layer at the surface. The maximum electron density is reached at a delay of 0.5 ps after the peak of the pump pulse, which is a strong indication of the occurrence of electronic avalanche. The results are further analyzed to determine the actual feedback of the evolution of the optical properties of the material on the pump pulse. We introduce an important new quantity, namely, the duration of absorption of the laser by the created plasma, corresponding to the actual timespan of laser absorption by inverse Bremsstrahlung. Our results indicate an increasing contribution of plasma absorption to the total material absorption upon raising the excitation fluence above the ablation threshold. The role of transient optical properties during the energy deposition stage is characterized and our results emphasize the necessity to take it into account for better understanding and control of femtosecond laser-dielectrics interaction.

  9. FUNCTIONALIZED SILICA AEROGELS: ADVANCED MATERIALS TO CAPTURE AND IMMOBILIZE RADIOACTIVE IODINE

    SciTech Connect (OSTI)

    Matyas, Josef; Fryxell, Glen E.; Busche, Brad J.; Wallace, Krys; Fifield, Leonard S.

    2011-11-16

    To support the future expansion of nuclear energy, an effective method is needed to capture and safely store radiological iodine-129 released during reprocessing of spent nuclear fuel. Various materials have been investigated to capture and immobilize iodine. In most cases, however, the materials that are effective for capturing iodine cannot subsequently be sintered/densified to create a stable composite that could be a viable waste form. We have developed chemically modified, highly porous, silica aerogels that show sorption capacities higher than 440 mg of I2 per gram at 150 C. An iodine uptake test in dry air containing 4.2 ppm of iodine demonstrated no breakthrough after 3.5 h and indicated a decontamination factor in excess of 310. Preliminary densification tests showed that the I2-loaded aerogels retained more than 92 wt% of I2 after thermal sintering with pressure assistance at 1200 C for 30 min. These high capture and retention efficiencies for I2 can be further improved by optimizing the functionalization process and the chemistry as well as the sintering conditions.

  10. Compressed Silica Aerogels for the Study of Superfluid [superscript 3]He

    SciTech Connect (OSTI)

    Pollanen, J.; Choi, H.; Davis, J.P.; Blinstein, S.; Lippman, T.M.; Lurio, L.B.; Mulders, N.; Halperin, W.P. (NIU); (Delaware); (NWU)

    2007-03-02

    We have performed Small Angle X-ray Scattering (SAXS) on uniaxially strained aerogels and measured the strain-induced structural anisotropy. We use a model to connect our SAXS results to anisotropy of the {sup 3}He quasiparticle mean free path in aerogel. Measurements of the low temperature phase diagram of superfluid {sup 3}He in 98% aerogel indicate a stable B-phase and a metastable A-like phase. Vicente et al. proposed that the relative stability of these phases can be attributed to local anisotropic scattering of the 3He quasiparticles by the aerogel network. This network consists of silica strands with a diameter of {approx} 30 {angstrom} and average separation {zeta}{sub a} {approx} 300 {angstrom}. Vicente et al. also proposed using uniaxial strain of the aerogel to produce global anisotropy. We have performed SAXS on two uniaxially strained aerogels and found that strain introduces anisotropy on the {approx}100 {angstrom} length scale. We relate this to anisotropy of the quasiparticle mean free path, {lambda}.

  11. A New Concept for the Fabrication of Hydrogen Selective Silica Membranes

    SciTech Connect (OSTI)

    Michael Tsapatsis

    2005-10-01

    It is attempted to synthesize hydrogen selective silica-based membranes through a novel thin film deposition concept. This report describes the progress made during the 1st Year of this award. All project Tasks, for Year 1, were completed and the first thin films were prepared and characterized. The goal of this work is to use crystalline layered silicates to form hydrogen selective membranes for use in high temperature hydrogen/carbon dioxide separations. It was proposed to: (A) Synthesize layered silicate materials; (B) Prepare dispersions of as synthesized or delaminated layered silicates; (C) Prepare membranes by coating the layered silicates on macro-mesoporous supports; and (D) Test the membranes for H{sub 2}/CO{sub 2} selectivity at high temperature and pressures and for structural and functional stability at high temperature in the presence of water vapor. All Year 1 project Tasks are completed. Layered silicate particles were synthesized hydrothermally. Crystal shape and size was optimized for the formation of thin films. Calcination procedures that avoid particle agglomeration were developed and suspensions of the calcined silicate particles were prepared. The silicate particles and suspensions were characterized by X-Ray Diffraction, Electron Microscopy and Dynamic Light Scattering. The characterization data indicate that plate like morphology, large aspect ratio and good dispersion have been achieved. A deposition process that leads to uniform, high-coverage ({approx}100%) coating of the layered silicate particles on porous alpha-alumina supports was developed.

  12. Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions

    SciTech Connect (OSTI)

    Pinto, S. R. C.; Ramos, M. M. D.; Gomes, M. J. M.; Buljan, M.; Chahboun, A.; Roldan, M. A.; Molina, S. I.; Bernstorff, S.; Varela, M.; Pennycook, S. J.; Barradas, N. P.; Alves, E.

    2012-04-01

    In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (Ge+SiO{sub 2})/SiO{sub 2} multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (Ge + SiO{sub 2}) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation along the growth direction can be tuned by changing the Ge-rich layer thickness. The average value of the quantum dots size along the lateral (in-plane) direction along with their lateral separation is not affected by the thickness of the Ge-rich layer. However, the thickness of the Ge-rich layer significantly affects the quantum dot ordering. In addition, we investigate the dependence of the multilayer average atomic composition and also the quantum dot crystalline quality on the deposition parameters.

  13. Sorption Phase of Supercritical CO2 in Silica Aerogel: Experiments and Mesoscale Computer Simulations

    SciTech Connect (OSTI)

    Rother, Gernot [ORNL; Vlcek, Lukas [ORNL; Gruszkiewicz, Miroslaw {Mirek} S [ORNL; Chialvo, Ariel A [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Banuelos, Jose Leo [ORNL; Wallacher, Dirk [Helmholtz-Zentrum Berlin; Grimm, Nico [Helmholtz-Zentrum Berlin; Cole, David [Ohio State University

    2014-01-01

    Adsorption of supercritical CO2 in nanoporous silica aerogel was investigated by a combination of experiments and molecular-level computer modeling. High-pressure gravimetric and vibrating tube densimetry techniques were used to measure the mean pore fluid density and excess sorption at 35 C and 50 C and pressures of 0-200 bar. Densification of the pore fluid was observed at bulk fluid densities below 0.7 g/cm3. Far above the bulk fluid density, near-zero sorption or weak depletion effects were measured, while broad excess sorption maxima form in the vicinity of the bulk critical density region. The CO2 sorption properties are very similar for two aerogels with different bulk densities of 0.1 g/cm3 and 0.2 g/cm3, respectively. The spatial distribution of the confined supercritical fluid was analyzed in terms of sorption- and bulk-phase densities by means of the Adsorbed Phase Model (APM), which used data from gravimetric sorption and small-angle neutron scattering experiments. To gain more detailed insight into supercritical fluid sorption, large-scale lattice gas GCMC simulations were utilized and tuned to resemble the experimental excess sorption data. The computed three-dimensional pore fluid density distributions show that the observed maximum of the excess sorption near the critical density originates from large density fluctuations pinned to the pore walls. At this maximum, the size of these fluctuations is comparable to the prevailing pore sizes.

  14. Interfacial Modification of Silica Surfaces Through gamma-Isocyanatopropyl Triethoxy Silane-Amine Coupling Reactions

    SciTech Connect (OSTI)

    Vogel,B.; DeLongchamp, D.; Mahoney, C.; Lucas, L.; Fischer, D.; Lin, E.

    2008-01-01

    The development of robust, cost-effective methods to modify surfaces and interfaces without the specialized synthesis of unique coupling agents could provide readily accessible routes to optimize and tailor interfacial properties. We demonstrate that -isocyanatopropyl triethoxysilane (ISO) provides a convenient route to functionalize silica surfaces through coupling reactions with readily available reagents. ISO coupling agents layers (CALs) can be prepared from toluene with triethylamine (TEA), but the coupling reaction of an amine to the ISO CAL does not proceed. We use near edge X-ray absorption fine structure (NEXAFS), time-of-flight secondary ion mass spectrometry (TOF-SIMS) and sessile drop contact angle to demonstrate the isocyanate layer is not degraded under coupling conditions. Access to silanes with chemical functionality is possible with ISO by performing the coupling reaction in solution and then depositing the product onto the surface. Two model CAL surfaces are prepared to demonstrate the ease and robust nature of this procedure. The surfaces prepared using this method are the ISO reacted with octadecylamine to produce a hydrocarbon surface of similar quality to octadecyl trichlorosilane (OTS) CALs and with 9-aminofluorene (AFL), an aromatic amine functionality whose silane is otherwise unavailable commercially.

  15. Monitoring, Modeling, and Diagnosis of Alkali-Silica Reaction in Small Concrete Samples

    SciTech Connect (OSTI)

    Agarwal, Vivek; Cai, Guowei; Gribok, Andrei V.; Mahadevan, Sankaran

    2015-09-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This report describes alkali-silica reaction (ASR) degradation mechanisms and factors influencing the ASR. A fully coupled thermo-hydro-mechanical-chemical model developed by Saouma and Perotti by taking into consideration the effects of stress on the reaction kinetics and anisotropic volumetric expansion is presented in this report. This model is implemented in the GRIZZLY code based on the Multiphysics Object Oriented Simulation Environment. The implemented model in the GRIZZLY code is randomly used to initiate ASR in a 2D and 3D lattice to study the percolation aspects of concrete. The percolation aspects help determine the transport properties of the material and therefore the durability and service life of concrete. This report summarizes the effort to develop small-size concrete samples with embedded glass to mimic ASR. The concrete samples were treated in water and sodium hydroxide solution at elevated temperature to study how ingress of sodium ions and hydroxide ions at elevated temperature impacts concrete samples embedded with glass. Thermal camera was used to monitor the changes in the concrete sample and results are summarized.

  16. Thermal conductivity studies of novel nanofluids based on metallic silver decorated mesoporous silica nanoparticles

    SciTech Connect (OSTI)

    Tadjarodi, Azadeh; Zabihi, Fatemeh

    2013-10-15

    Graphical abstract: - Highlights: Metallic silver was decorated in mSiO{sub 2} with grafted hemiaminal functional groups. Synthesized nanoparticles were used for preparation of glycerol based nanofluids. The effect of temperature, weight fraction of mSiO{sub 2} and concentration of silver nanoparticles on thermal conductivity of nanofluids was investigated. - Abstract: In the present study, the mesoporous structure of silica (mSiO{sub 2}) nanoparticles as well as hemiaminal grafted mSiO{sub 2} decorated by metallic silver (Ag/mSiO{sub 2}) has been used for the preparation of glycerol based nanofluids. Structural and morphological characterization of the synthesized products have been carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), UVvis spectroscopy, inductively coupled plasma (ICP) and N{sub 2} adsorptiondesorption isotherms. The thermal conductivity and viscosity of the nanofluids have been measured as a function of temperature for various weight fractions and silver concentrations of mSiO{sub 2} and Ag/mSiO{sub 2} nanoparticles, respectively. The results show that the thermal conductivity of the nanofluids increase up to 9.24% as the weight fraction of mSiO{sub 2} increases up to 4 wt%. Also, increasing the percent of the silver decorated mSiO{sub 2} (Ag/mSiO{sub 2}) up to 2.98% caused an enhancement in the thermal conductivity of the base fluid up to 10.95%. Furthermore, the results show that the nanofluids have Newtonian behavior in the tested temperature range for various concentrations of nanoparticles.

  17. FORMATION OF CALCIUM AND SILICA FROM PERCOLATION IN A HYDROLOGICALLY UNSATURATED SETTING, Y.M.,NV

    SciTech Connect (OSTI)

    J.B. Paces; J.F. Whelan; Z.E. Peterman; B.D. Marshall

    2000-07-27

    Geological, mineralogical, chemical, and isotopic evidence from coatings of calcite and silica on open fractures and lithophysal cavities within welded tuffs at Yucca Mountain indicate an origin from meteoric water percolating through a thick (500 to 700 m) unsaturated zone (UZ) rather than from pulses of ascending ground water. Geologic evidence for a UZ setting includes the presence of coatings in only a small percentage of cavities, the restriction of coatings to fracture footwalls and cavity floors, and an absence of mineral high-water marks indicative of water ponding. Systematic mineral sequences (early calcite, followed by chalcedony with minor quartz and fluorite, and finally calcite with intercalated opal forming the bulk of the coatings) indicate progressive changes in UZ conditions through time, rather than repeated saturation by flooding. Percolation under the influence of gravity also results in mineral textures that vary between steeply dipping sites (thinner coatings of blocky calcite) and shallowly dipping sites (thicker coatings of coarse, commonly bladed calcite, with globules and sheets of opal). Micrometer-scale growth banding in both calcite and opal reflects slow average growth rates (scale of mm/m.y.) over millions of years rather than only a few rapidly deposited growth episodes. Isotopic compositions of C, O, Sr, and U from calcite and opal indicate a percolation-modified meteoric water source, and collectively refute a deeper ground-water source. Chemical and isotopic variations in coatings also indicate long-term evolution of water compositions. Although some compositional changes are related to shifts in climate, growth rates in the deeper UZ are buffered from large changes in meteoric input. Coatings most likely formed from films of water flowing down connected fracture pathways. Mineral precipitation is consistent with water vapor and carbon dioxide loss from films at very slow rates. Data collectively indicate that mineral coatings formed in a UZ setting that has been hydrologically stable over million-year time scales.

  18. Solubility of aluminum and silica in Spodic horizons as affected by drying and freezing

    SciTech Connect (OSTI)

    Simonsson, M.; Berggren, D.; Gustafsson, J.P.

    1999-10-01

    The release of toxic Al{sup 3+} is one of the most serious consequences of anthropogenic soil acidification. Therefore, the mechanisms controlling Al solubility have been a topic of intense research for more than a decade. For convenience, soil samples are often dried before storage and experimental use. However, the literature offers examples of drying that results in changes in pH, solubility of organic matter, and dissolution rates of Al. In this study, the authors examined the solubility of Al and Si in fresh soil and in soil that had been dried or deep-frozen. Five Spodosol B horizon soils were subjected to batch titrations, where portions of each soil were equilibrated with solutions with varying concentrations of acid or base added. Extractions with acid oxalate and Na pyrophosphate indicated the presence of imogolite-type materials (ITM) in three of the soils. In the other two soils most secondary solid-phase Al was associated with humic substances. Deep-freezing did not significantly change pH nor the concentration of Al or Si as compared with fresh soil. Drying, on the other hand, yielded pH increases of up to 0.3 units at a given addition of acid or base, whereas Al{sup 3+} changed only slightly, implying a higher Al solubility in all of the soils. Furthermore, dissolved silica increased by up to 200% after drying, except in a soil that almost completely lacked oxalate-extractable Si. The authors suggest that drying enhanced the dissolution of ITM by disrupting soil organic matter, thus exposing formerly coated mineral surfaces. In the soil where dissolved Si did not change with drying, it has been demonstrated that Al-humus complexes controlled Al solubility. They suggest that fissures in the organic material caused by drying may have exposed formerly occluded binding sites that had a higher Al saturation than had sites at the surface of humus particles.

  19. Bio-distribution and metabolic paths of silica coated CdSeS quantum dots

    SciTech Connect (OSTI)

    Chen Zhen; Chen Hu; Meng Huan; Xing Gengmei Gao Xueyun; Sun Baoyun; Shi Xiaoli; Yuan Hui; Zhang Chengcheng; Liu Ru; Zhao Feng

    2008-08-01

    With the rapid development of quantum dot (QD) technology, water-soluble QDs have the prospect of being used as a biological probe for specific diagnoses, but their biological behaviors in vivo are little known. Our recent in vivo studies concentrated on the bio-kinetics of QDs coated by hydroxyl group modified silica networks (the QDs are 21.3 {+-} 2.0 nm in diameter and have maximal emission at 570 nm). Male ICR mice were intravenously given the water-soluble QDs with a single dose of 5 nmol/mouse. Inductively coupled plasma-mass spectrometry was used to measure the {sup 111}Cd content to indicate the concentration of QDs in plasma, organs, and excretion samples collected at predetermined time intervals. Meanwhile, the distribution and aggregation state of QDs in tissues were also investigated by pathological examination and differential centrifugation. The plasma half-life and clearance of QDs were 19.8 {+-} 3.2 h and 57.3 {+-} 9.2 ml/h/kg, respectively. The liver and kidney were the main target organs for QDs. The QDs metabolized in three paths depending on their distinct aggregated states in vivo. A fraction of free QDs, maintaining their original form, could be filtered by glomerular capillaries and excreted via urine as small molecules within five days. Most QDs bound to protein and aggregated into larger particles that were metabolized in the liver and excreted via feces in vivo. After five days, 8.6% of the injected dose of aggregated QDs still remained in hepatic tissue and it was difficult for this fraction to clear.

  20. Residual stress and damage-induced critical fracture on CO2 laser treated fused silica

    SciTech Connect (OSTI)

    Matthews, M; Stolken, J; Vignes, R; Norton, M

    2009-11-02

    Localized damage repair and polishing of silica-based optics using mid- and far-IR CO{sub 2} lasers has been shown to be an effective method for increasing optical damage threshold in the UV. However, it is known that CO{sub 2} laser heating of silicate surfaces can lead to a level of residual stress capable of causing critical fracture either during or after laser treatment. Sufficient control of the surface temperature as a function of time and position is therefore required to limit this residual stress to an acceptable level to avoid critical fracture. In this work they present the results of 351 nm, 3 ns Gaussian damage growth experiments within regions of varying residual stress caused by prior CO{sub 2} laser exposures. Thermally stressed regions were non-destructively characterized using polarimetry and confocal Raman microscopy to measure the stress induced birefringence and fictive temperature respectively. For 1 {approx} 40s square pulse CO{sub 2} laser exposures created over 0.5-1.25 kW/cm{sup 2} with a 1-3 mm 1/e{sup 2} diameter beam (T{sub max} {approx} 1500-3000 K), the critical damage site size leading to fracture increases weakly with peak temperature, but shows a stronger dependence on cooling rate, as predicted by finite element hydrodynamics simulations. Confocal micro-Raman was used to probe structural changes to the glass over different thermal histories and indicated a maximum fictive temperature of 1900K for T{sub max} {ge} 2000 K. The effect of cooling rate on fictive temperature caused by CO{sub 2} laser heating are consistent with finite element calculations based on a Tool-Narayanaswamy relaxation model.

  1. Electron paramagnetic resonance study of paramagnetic centers in carbon-fumed silica adsorbent

    SciTech Connect (OSTI)

    Savchenko, D. V.; Shanina, B. D.; Kalabukhova, E. N.; Sitnikov, A. A.; Lysenko, V. S.; Tertykh, V. A.

    2014-04-07

    Fumed silica A-300 was carbonized by means of pyrolysis of CH{sub 2}Cl{sub 2}. The obtained initial SiO{sub 2}:C nanopowders of black color, with an average diameter of 1416?nm and carbon (C) concentration 7?wt. %, subjected to the oxidation and passivation treatment were studied by electron paramagnetic resonance (EPR) in the temperature range 4400?K. Two EPR signals of Lorentzian lineshape with nearly equal g-factors and different linewidth were observed in the initial, oxidized, and passivated SiO{sub 2}:C nanopowders. The two-component EPR spectrum was explained by the presence of C in two electronic states. The intensive narrow EPR signal, which has a temperature-dependent intensity, linewidth, and resonance field position, was attributed to the carbon-related defect with non-localized electron hopping between neighboring C-dangling bonds. The striking effect is that the temperature dependence of the EPR linewidth demonstrates the motional narrowing of the EPR signal at very low temperatures from 4?K to 20?K, which is not typically for nonmetallic materials and was explained by the quantum character of C layer conductivity in the SiO{sub 2}:C. The observed peaks in the temperature dependence of the conduction electron EPR signal integral intensity in the high-temperature range 200440?K was explained by the presence of the C nanodots at the surface of SiO{sub 2} nanoparticles and the ejection of electrons from the confinement energy levels of C quantum dot when the temperature becomes comparable to the confinement energy.

  2. Chemical behaviour of geothermal silica after precipitation from geothermal fluids with inorganic flocculating agents at the Hawaii Geothermal Project Well-A (HGP-A)

    SciTech Connect (OSTI)

    De Carlo, E.H.

    1987-01-01

    The report summarizes the results of experiments dealing with the problem of removal of waste-silica from spent fluids at the experimental power generating facility in the Puna District of the island of Hawaii. Geothermal discharges from HGP-A represent a mixture of meteoric and seawaters which has reacted at depth with basalts from the Kilauea East Rift Zone under high pressure and temperature. After separation of the steam phase of the geothermal fluid from the liquid phase and a final flashing stage to 100 degrees Celsius and atmospheric pressure, the concentration of the silica increases to approximately 1100 mg/L. This concentration represents five to six times the solubility of amorphous silica in this temperature range. We have evaluated and successfully developed bench scale techniques utilizing adsorptive bubble flotation for the removal of colloidal silica from the spent brine discharge in the temperature range of 60 to 90 degrees C. The methods employed resulted in recovery of up to 90% of the silica present above its amorphous solubility in the experimental temperature range studied.

  3. Simulations of the infrared, Raman, and 2D-IR photon echo spectra of water in nanoscale silica pores

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Burris, Paul C.; Laage, Damien; Thompson, Ward H.

    2016-05-20

    Vibrational spectroscopy is frequently used to characterize nanoconfined liquids and probe the effect of the confining framework on the liquid structure and dynamics relative to the corresponding bulk fluid. However, it is still unclear what molecular-level information can be obtained from such measurements. In this Paper, we address this question by using molecular dynamics (MD) simulations to reproduce the linear infrared (IR), Raman, and two-dimensional IR (2D-IR) photon echo spectra for water confined within hydrophilic (hydroxyl-terminated) silica mesopores. To simplify the spectra the OH stretching region of isotopically dilute HOD in D2O is considered. An empirical mapping approach is usedmore » to obtain the OH vibrational frequencies, transition dipoles, and transition polarizabilities from the MD simulations. The simulated linear IR and Raman spectra are in good general agreement with measured spectra of water in mesoporous silica reported in the literature. The key effect of confinement on the water spectrum is a vibrational blueshift for OH groups that are closest to the pore interface. The blueshift can be attributed to the weaker hydrogen bonds (H-bonds) formed between the OH groups and silica oxygen acceptors. Non-Condon effects greatly diminish the contribution of these OH moieties to the linear IR spectrum, but these weaker H-bonds are readily apparent in the Raman spectrum. The 2D-IR spectra have not yet been measured and thus the present results represent a prediction. Lastly, the simulated spectra indicate that it should be possible to probe the slower spectral diffusion of confined water compared to the bulk liquid by analysis of the 2D-IR spectra.« less

  4. Revisiting Maxwell’s accommodation coefficient: A study of nitrogen flow in a silica microtube across all flow regimes

    SciTech Connect (OSTI)

    Lei, Wenwen McKenzie, David R.

    2014-12-15

    Gas flows have been studied quantitatively for more than a hundred years and have relevance in modern fields such as the control of gas inputs to processes, the measurement of leak rates and the separation of gaseous species. Cha and McCoy have derived a convenient formula for the flow of an ideal gas applicable across a wide range of Knudsen numbers (Kn) that approaches the Navier–Stokes equations at small Kn and the Smoluchowski extension of the Knudsen flow equation at large Kn. Smoluchowski’s result relies on the Maxwell definition of the tangential momentum accommodation coefficient α, recently challenged by Arya et al. We measure the flow rate of nitrogen gas in a smooth walled silica tube across a wide range of Knudsen numbers from 0.0048 to 12.4583. We find that the nitrogen flow obeys the Cha and McCoy equation with a large value of α, unlike carbon nanotubes which show flows consistent with a small value of α. Silica capillaries are therefore not atomically smooth. The flow at small Kn has α=0.91 and at large Kn has α close to one, consistent with the redefinition of accommodation coefficient by Arya et al., which also resolves a problem in the literature where there are many observations of α of less than one at small Kn and many equal to one at large Kn. Silica capillaries are an excellent choice for an accurate flow control system. - Highlights: • First experimental study on flow rate across all flow regimes in a well-defined microtube. • Extend Cha and McCoy theory for molecular flow regime. • Demonstrate the Maxwell accommodation coefficient is different in the slip and molecular flow regimes.

  5. A STUDY OF FISCHER 344 RATS EXPOSED TO SILICA DUST FOR SIX MONTHS AT CONCENTRATIONS OF 0, 2, 10 OR 20 MG / M3.

    SciTech Connect (OSTI)

    KUTZMAN,R.S.

    1984-02-01

    The major objective of this study was to relate the results of a series of functional tests to the compositional and structural alterations in the rat lung induced by subchronic exposure to silica dust. Fischer-344 rats were exposed for 6 hours/day, 5 days/week for 6 months to either 0, 2, 10, or 20 mg SiO{sub 2}/m{sup 3}. The general appearance of the exposed rats was not different from that of the controls. Interestingly, female rats exposed to silica dust, at all tested concentrations, gained more weight than the controls. The lung weight and the lung-to-body weight ratio was greater in the male rats exposed to the highest concentration of silica dust.

  6. Effect of Siloxane Ring Strain and Cation Charge Density on the Formation of Coordinately Unsaturated Metal Sites on Silica: Insights from DFT Studies

    SciTech Connect (OSTI)

    Das, Ujjal; Zhang, Guanghui; Hu, Bo; Hock, Adam S.; Redfern, Paul C.; Miller, Jeffrey T.; Curtiss, Larry A.

    2015-12-01

    Amorphous silica (SiO2) is commonly used as a support in heterogeneous catalysis. However, due to the structural disorder and temperature induced change of surface morphology, the structures of silica supported metal catalysts are difficult to determine. Most studies are primarily focused on understanding the interactions of different types of surface hydroxyl groups with metal ions. In comparison, the effect of siloxane ring size on the structure of silica supported metal catalysts and how it affects catalytic activity is poorly understood. Here, we have used density functional theory calculations to understand the effect of siloxane ring strain on structure and activity of different monomeric Lewis acid metal sites on silica. In particular, we have found that large siloxane rings favor strong dative bonding interaction between metal ion and surface hydroxyls, leading to the formation of high-coordinate metal sites. In comparison, metal-silanol interaction is weak in small siloxane rings, resulting in low-coordinate metal sites. The physical origin of this size dependence is associated with siloxane ring strain, and, a correlation between metal-silanol interaction energy and ring strain energy has been observed. In addition to ring strain, the strength of the metal-silanol interaction also depends on the positive charge density of the cations. In fact, a correlation also exists between metal-silanol interaction energy and charge density of several first-row transition and post-transition metals. The theoretical results are compared with the EXAFS data of monomeric Zn(II) and Ga(III) ions grafted on silica. The molecular level insights of how metal ion coordination on silica depends on siloxane ring strain and cation charge density will be useful in the synthesis of new catalysts.

  7. Sol-gel Ru/SiO[sub 2] - catalysts: Theoretical and experimental determination of the Ru-in-silica structures

    SciTech Connect (OSTI)

    Lopez, T.; Gomez, R.; Novaro, O. ); Ramirez-Solis, A.; Sanchez-Mora, E.; Castillo, S.; Poulain, E.; Martinez-Magadan, J.M. )

    1993-05-01

    Preparation of Ru/SiO[sub 2] catalysts with sol-gel techniques allows better selectivity and much greater resistance to coke formation and deactivation than the traditional impregnation method. This has been attributed to the incorporation of Ru into the silica network for the sol-gel catalyst. To further understand the structure of the Ru occluded in the silica network, a variety of spectroscopical studies and quantum mechanical calculations were carried out, confirming previously proposed structures and showing good agreement between the theoretical and experimental results. 26 refs., 10 figs., 2 tabs.

  8. Densification of alkoxide-derived fine silica powder compact by ultra-high-pressure cold isostatic pressing

    SciTech Connect (OSTI)

    Kamiya, Hidehiro . Dept. of Chemical Engineering); Suzuki, Hisao ); Kato, Daisuke; Jimbo, Genji . Dept. of Chemical Engineering)

    1993-01-01

    Powder compacts of alkoxide-derived fine silica powders were consolidated into a highly dense and uniform structure by ultra-high-pressure cold isostatic pressing of granules with controlled structure. The diameters of spherical and nearly monosized amorphous silica particles, prepared from metal alkoxide, were successfully controlled in the range of 9 to 760 nm by varying the concentration of ammonia. Close-packed granules of these powders were produced by spray drying. These powders were isostatically pressed up to 1 GPa at room temperature. Although the average particle diameter was less than 100 nm, the maximum relative density of the compacts was more than 78% of theoretical density. The optimum particle size to obtain highly dense compacts was in the range of 30 to 300 nm at 1 GPa. Furthermore, the ratio of mode pore diameter in these compacts to particle diameter was less than 0.155, which corresponded to the minimum ratio of calculated three-particle pore channel radii for hexagonal close packing. Viscous deformation of particles under ultra-high isostatic pressure played an important role in the densification of the compacts.

  9. Nanoporous Polytetrafluoroethylene/Silica Composite Separator as a High-Performance All-Vanadium Redox Flow Battery Membrane

    SciTech Connect (OSTI)

    Wei, Xiaoliang; Nie, Zimin; Luo, Qingtao; Li, Bin; Chen, Baowei; Simmons, Kevin L.; Sprenkle, Vincent L.; Wang, Wei

    2013-09-02

    Driven by the motivation of searching for low-cost membrane alternatives, a novel nanoporous polytetrafluoroethylene/silica composite separator has been prepared and evaluated for its use in all-vanadium mixed-acid redox flow battery. This separator consisting of silica particles enmeshed in a polytetrafluoroethylene fibril matrix has no ion exchange capacity and is featured with unique nanoporous structures, which function as the ion transport channels in redox flow battery operation, with an average pore size of 38nm and a porosity of 48%. This separator has produced excellent electrochemical performance in the all-vanadium mixed-acid system with energy efficiency delivery comparable to Nafion membrane and superior rate capability and temperature tolerance. The separator also demonstrates an exceptional capacity retention capability over extended cycling, offering additional operational latitude towards conveniently mitigating the capacity decay that is inevitable for Nafion. Because of the inexpensive raw materials and simple preparation protocol, the separator is particularly low-cost, estimated to be at least an order of magnitude more inexpensive than Nafion. Plus the proven chemical stability due to the same backbone material as Nafion, this separator possesses a good combination of critical membrane requirements and shows great potential to promote market penetration of the all-vanadium redox flow battery by enabling significant reduction of capital and cycle costs.

  10. Application of Fourier transform infrared spectroscopy to silica diagenesis: The opal-A to opal-CT transformation

    SciTech Connect (OSTI)

    Rice, S.B.; Freund, H.; Huang, W.L.; Clouse, J.A.; Isaacs, C.M.

    1995-10-02

    An important goal in silica diagenesis research is to understand the kinetics of opal transformation from noncrystalline opal-A to the disordered silica polymorph opal-CT. Because the conventional technique for monitoring the transformation, powder X-ray diffraction (XRD), is applicable only to phases with long-range order, the authors used Fourier transform infrared spectroscopy (FTIR) to monitor the transformation. They applied this technique, combined with XRD and TEM, to experimental run products and natural opals from the Monterey Formation and from siliceous deposits in the western Pacific Ocean. Using a ratio of two infrared absorption intensities ({omega} = I{sub 472 cm{sup {minus}1}}/I{sub 500 cm{sup {minus}1}}), the relative proportions of opal-A and opal-CT can be determined. The progress of the transformation is marked by changes in slope of {omega} vs. depth or time when a sufficient stratigraphic profile is available. There are three stages in the opal-A to opal-CT reaction: (1) opal-A dissolution; (2) opal-CT precipitation, whose end point is marked by completion of opal-A dissolution; and (3) opal-CT ordering, during which tridymite stacking is eliminated in favor of crystobalite stacking.

  11. Absorption of a single 500 fs laser pulse at the surface of fused silica: Energy balance and ablation efficiency

    SciTech Connect (OSTI)

    Varkentina, N.; Sanner, N.; Lebugle, M.; Sentis, M.; Utéza, O.

    2013-11-07

    Ablation of fused silica by a single femtosecond laser pulse of 500 fs pulse duration is investigated from the perspective of efficiency of incident photons to remove matter. We measure the reflected and transmitted fractions of the incident pulse energy as a function of fluence, allowing us to recover the evolution of absorption at the material surface. At the ablation threshold fluence, 25% of incident energy is absorbed. At high fluences, this ratio saturates around 70% due to the appearance of a self-triggered plasma mirror (or shielding) effect. By using the energy balance retrieved experimentally and measurements of the ablated volume, we show that the amount of absorbed energy is far above the bonding energy of fused silica at rest and also above the energy barrier to ablate the material under non-equilibrium thermodynamic conditions. Our results emphasize the crucial role of transient plasma properties during the laser pulse and suggest that the major part of the absorbed energy has been used to heat the plasma formed at the surface of the material. A fluence range yielding an efficient and high quality ablation is also defined, which makes the results relevant for femtosecond micromachining processes.

  12. Sub-micron fracture mechanism in silica-based glass activated by permanent densification from high-strain loading

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wereszczak, Andrew A.; Waters, Shirley B.; Parten, Randy J.; Pye, L. David

    2016-04-26

    Several silica-based glasses were fractured at high strain energy via drop-weight testing on small specimens. A cylindrical specimen geometry was chosen to promote initially simple, axisymmetric, and uniform compressive loading. The imposed uniaxial compressive strain at impact was sufficiently high to qualitatively cause permanent densification. Produced fragments were collected for postmortem and a fraction of them, for all the silica-based glasses, consistently had distinct sub-micron-sized fractures (~ 300–1000 nm), designated here as “microkernels”, on their surfaces. They would most often appear as a sub-micron pore on the fragment - apparently if the microkernel had popped out as a consequence ofmore » the local crack plane running through it, tensile-strain release, and the associated formation of the fragment it was on. No fractographic evidence was found to show the microkernels were associated with local failure initiation. However, their positioning and habit sometimes suggested they were associated with localized crack branching and that they could have influenced secondary fracturing that occurred during overall crushing and comminution and associated fragment size and shape creation. Furthermore, the size range of these microkernels is much too small to affect structural flexure strength of these glasses for most applications but are of a size and concentration that may affect their ballistic, shock, crush, and comminution responses when permanent densification is concomitantly occurring.« less

  13. Examination of the concrete from an old Portuguese dam: Texture and composition of alkali-silica gel

    SciTech Connect (OSTI)

    Fernandes, Isabel Noronha, Fernando Teles, Madalena

    2007-11-15

    Exudations and pop-outs were identified in the interior galleries of a large dam built in the 1960s. The samples collected were examined by a Scanning Electron Microscope. A dense material with a smooth surface and drying shrinkage cracks or a spongy texture were observed in the samples. The semi-quantitative composition was obtained by energy dispersive spectrometry (EDS) and it was concluded that this material corresponds to alkali-silica gel, composed of SiO{sub 2}-Na{sub 2}O-K{sub 2}O-CaO. A viscous white product in contact with an aggregate particle in a cone sampled from a pop-out was observed through use of the scanning electron microscope and it has characteristics similar to the gel present in the exudations and cavities. Reference is made to the potential alkali reactivity of the aggregate present in the concrete. The texture and composition of the products probably resulting from an alkali-silica reaction are presented, set out in ternary diagrams, and discussed.

  14. Synthesis of silica coated zinc oxidepoly(ethylene-co-acrylic acid) matrix and its UV shielding evaluation

    SciTech Connect (OSTI)

    Ramasamy, Mohankandhasamy; Kim, Yu Jun; Gao, Haiyan; Yi, Dong Kee; An, Jeong Ho

    2014-03-01

    Graphical abstract: - Highlights: Well layer thickness controlled silica shell was made on ZnO nanoparticles. PEAA, an interfacial agent is used to make nanocompositepolymer matrix by twin-screw extruder. Si-ZnO/PEAA matrix is highly stable and UV protective as compared to ZnO/PEAA matrix. Nanoparticle embedded polymer matrix is suggested to make UV shielding fabrics with Nylon4. - Abstract: Silica coated zinc oxide nanoparticles (Si-ZnO NPs) (7 nm thick) were synthesized successfully and melt blended with poly(ethylene-co-acrylic acid) (PEAA resin) to improving ultraviolet (UV) shielding of zinc oxide nanoparticles (ZnO NPs). The photostability of both the ZnO NPs and Si-ZnO NPs were analyzed by the difference in photoluminescence (PL) and by methylene blue (MB) degradation. Photo-degradation studies confirmed that Si-ZnO NPs are highly photostable compared to ZnO NPs. The melt blended matrices were characterized by field emission scanning electron microscopy interfaced with energy dispersive X-ray spectroscopy (FE-SEM-EDX). The UV shielding property was analyzed from the transmittance spectra of UVvisible (UVvis) spectroscopy. The results confirmed fine dispersion of thick Si-ZnO NPs in the entire resin matrix. Moreover, the Si-ZnO/PEAA showed about 97% UV shielding properties than the ZnO/PEAA.

  15. Silica exposure to excavation workers during the excavation of a low level radiological waste pit and tritium disposal shafts

    SciTech Connect (OSTI)

    Wilson, K.M.

    1995-01-01

    This study evaluated the task-length average (TLA) respirable dust and respirable silica airborne concentrations to which construction workers excavating volcanic tuff at Los Alamos National Laboratory (LANL) were exposed. These workers were excavating a low level radiological waste disposal pit of final dimensions 720 feet long, 132 feet wide and 60 feet deep. The objectives of this study were as follows: (1) evaluate exposures; (2) determine if the type of machinery used affects the respirable dust concentration in the breathing zone of the worker; (3) evaluate the efficacy of wetting the pit to reduce the respirable dust exposure; and (4) determine if exposure increases with increasing depth of pit due to the walls of the pit blocking the cross wind ventilation.

  16. Growth of tapered silica nanowires with a shallow U-shaped vapor chamber: Growth mechanism and structural and optical properties

    SciTech Connect (OSTI)

    Zhang, Danqing; Zhang, Xi Wei, Jianglin; Gu, Gangxu; Xiang, Gang

    2015-04-28

    Traditional chemical vapor deposition method modified with a shallow U-shaped vapor chamber has been used to synthesize tapered bamboo shoot-like (BS-like) amorphous SiO{sub 2} nanowires (NWs) on Si (100) substrates without catalyst. The key innovation of this approach lies in a creation of swirling flow of the reactant vapors during the growth, which leads to a harvest of tapered silica NWs with lengths up to several microns. The unique structures and corresponding luminescence properties of the BS-like NWs were studied and their relationship with the evaporated active reactants was explored. A thermodynamic model that considers the critical role of the vapor flow during the growth is proposed to understand the structural and optical features. The shallow U-shaped vapor chamber-aided approach may provide a viable way to tailor novel structure of NWs for potential applications in nano-devices.

  17. Development of EEM based siliconwater and silicawater wall potentials for non-reactive molecular dynamics simulations

    SciTech Connect (OSTI)

    Kim, Junghan; Iype, Eldhose; Frijns, Arjan J.H.; Nedea, Silvia V.; Steenhoven, Anton A. van

    2014-07-01

    Molecular dynamics simulations of heat transfer in gases are computationally expensive when the wall molecules are explicitly modeled. To save computational time, an implicit boundary function is often used. Steele's potential has been used in studies of fluidsolid interface for a long time. In this work, the conceptual idea of Steele's potential was extended in order to simulate watersilicon and watersilica interfaces. A new wall potential model is developed by using the electronegativity-equalization method (EEM), a ReaxFF empirical force field and a non-reactive molecular dynamics package PumMa. Contact angle simulations were performed in order to validate the wall potential model. Contact angle simulations with the resulting tabulated wall potentials gave a siliconwater contact angle of 129, a quartzwater contact angle of 0, and a cristobalitewater contact angle of 40, which are in reasonable agreement with experimental values.

  18. A physical model of the photo- and radiation-induced degradation of ytterbium-doped silica optical fibres

    SciTech Connect (OSTI)

    Mady, Franck Duchez, Jean-Bernard Mebrouk, Yasmine Benabdesselam, Mourad

    2014-10-21

    We propose a model to describe the photo- or/and the radiation-induced darkening of ytterbium-doped silica optical fibers. This model accounts for the well-established experimental features of photo-darkening. Degradation behaviors predicted for fibers pumped in harsh environments are also fully confirmed by experimental data reported in the work by Duchez et al. (this proceeding), which gives a detailed characterization of the interplay between the effects of the pump and those of a superimposed ionizing irradiation (actual operation conditions in space-based applications for instance). In particular, dependences of the darkening build-up on the pump power, the total ionizing dose and the dose rate are all correctly reproduced. The presented model is a sufficient one, including the minimal physical ingredients required to reproduce experimental features. Refinements could be proposed to improve, e.g., quantitative kinetics.

  19. Characteristics of ultra low-k nanoporous and fluorinated silica based films prepared by plasma enhanced chemical vapor deposition

    SciTech Connect (OSTI)

    Abbasi-Firouzjah, M.; Shokri, B.; Physics Department, Shahid Beheshti University G.C., Evin, Tehran

    2013-12-07

    Low dielectric constant (low-k) silica based films were deposited on p-type silicon and polycarbonate substrates by radio frequency (RF) plasma enhanced chemical vapor deposition method at low temperature. A mixture of tetraethoxysilane vapor, oxygen, and tetrafluoromethane (CF{sub 4}) was used for the deposition of the films in forms of two structures called as SiO{sub x}C{sub y} and SiO{sub x}C{sub y}F{sub z}. Properties of the films were controlled by amount of porosity and fluorine content in the film matrix. The influence of RF power and CF{sub 4} flow on the elemental composition, deposition rate, surface roughness, leakage current, refractive index, and dielectric constant of the films were characterized. Moreover, optical emission spectroscopy was applied to monitor the plasma process at the different parameters. Electrical characteristics of SiO{sub x}C{sub y} and SiO{sub x}C{sub y}F{sub z} films with metal-oxide-semiconductor structure were investigated using current-voltage analysis to measure the leakage current and breakdown field, as well as capacitance-voltage analysis to obtain the film's dielectric constant. The results revealed that SiO{sub x}C{sub y} films, which are deposited at lower RF power produce more leakage current, meanwhile the dielectric constant and refractive index of these films decreased mainly due to the more porosity in the film structure. By adding CF{sub 4} in the deposition process, fluorine, the most electronegative and the least polarized atom, doped into the silica film and led to decrease in the refractive index and the dielectric constant. In addition, no breakdown field was observed in the electrical characteristics of SiO{sub x}C{sub y}F{sub z} films and the leakage current of these films reduced by increment of the CF{sub 4} flow.

  20. Comparison of laser-based mitigation of fused silica surface damage using mid- versus far-infrared lasers

    SciTech Connect (OSTI)

    Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J

    2009-12-16

    Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.

  1. A density functional theory study of the oxidation of methanol to formaldehyde over vanadia supported on silica, titania, and zirconia

    SciTech Connect (OSTI)

    Khaliullin, Rustam Z.; Bell, Alexis T.

    2002-09-05

    Density functional theory was used to investigate the mechanism and kinetics of methanol oxidation to formaldehyde over vanadia supported on silica, titania, and zirconia. The catalytically active site was modeled as an isolated VO{sub 4} unit attached to the support. The calculated geometry and vibrational frequencies of the active site are in good agreement with experimental measurements both for model compounds and oxide-supported vanadia. Methanol adsorption is found to occur preferentially with the rupture of a V-O-M bond (M = Si, Ti, Zr) and with preferential attachment of a methoxy group to V. The vibrational frequencies of the methoxy group are in good agreement with those observed experimentally as are the calculated isobars. The formation of formaldehyde is assumed to occur via the transfer of an H atom of a methoxy group to the O atom of the V=O group. The activation energy for this process is found to be in the range of 199-214 kJ/mol and apparent activation energies for the overall oxidation of methanol to formaldehyde are predicted to lie in the range of 112-123 kJ/mol, which is significantly higher than that found experimentally. Moreover, the predicted turnover frequency (TOF) for methanol oxidation is found to be essentially independent of support composition, whereas experiments show that the TOF is 10{sup 3} greater for titania- and zirconia-supported vanadia than for silica-supported vanadia. Based on these findings, it is proposed that the formation of formaldehyde from methoxy groups may require pairs of adjacent VO{sub 4} groups or V{sub 2}O{sub 7} dimer structures.

  2. SERI Desiccant Cooling Test Facility. Status report. Preliminary data on the performance of a rotary parallel-passage silica-gel dehumidifier

    SciTech Connect (OSTI)

    Schultz, K.J.

    1986-04-01

    This report describes the SERI Desiccant Cooling Test Facility. The facility can test bench-scale rotary dehumidifiers over a wide range of controlled conditions. We constructed and installed in the test loop a prototype parallel-passage rotary dehumidifier that has spirally wound polyester tape coated with silica gel. The initial tests gave satisfactory results indicating that approximately 90% of the silica gel was active and the overall Lewis number of the wheel was near unity. The facility has several minor difficulties including an inability to control humidity satisfactorily and nonuniform and highly turbulent inlet velocities. To completely validate the facility requires a range of dehumidifier designs. Several choices are available including constructing a second parallel-passage dehumidifier with the passage spacing more uniform.

  3. High-resolution study of photoinduced modification in fused silica produced by a tightly focused femtosecond laser beam in the presence of aberrations

    SciTech Connect (OSTI)

    Hnatovsky, C.; Taylor, R.S.; Simova, E.; Bhardwaj, V.R.; Rayner, D.M.; Corkum, P.B.

    2005-07-01

    An ultrahigh-resolution (20 nm) technique of selective chemical etching and atomic force microscopy has been used to study the photoinduced modification in fused silica produced at various depths by tightly focused femtosecond laser radiation affected by spherical aberration. We demonstrate that shapes of the irradiated zones near the threshold for modification can be predicted by taking proper account of spherical aberration caused by the refractive index mismatched air-silica interface. We establish a depth dependence of the pulse energy required to initiate modification and characterize the relationship between numerical aperture of the writing lens and practically achievable writing depth. We also show that spatial characteristics of the laser-modified zones can be controlled by a specially designed focusing system which allows correction for a variable amount of spherical aberration.

  4. NMR study of the molecular dynamics of ethanol and 2,2,2-trifluoroethanol liquids confined to nanopores of porous silica glasses

    SciTech Connect (OSTI)

    Ballard, L.; Jonas, J.

    1996-05-29

    A dynamic nuclear magnetic resonance (NMR) study of the polar fluids ethanol (EtOH) and 2,2,2-trifluoroethanol (TFE) confined to porous silica sol-gel glasses is reported. The {sup 13}C NMR spin-lattice relaxation times, T{sub 1}, were measured in glasses with pore radii ranging from 18.9 to 54.8 A, over a temperature range from -13.6 to 30.5{degree}C. The data were analyzed in terms of the two-state, fast exchange model, and surface layer relaxation times, T{sub 1s}, were calculated. On the basis of surface enhancement factors, T{sub 1b}/T{sub 1s}, where T{sub 1b} is the relaxation time of the bulk liquid, it was concluded that the more acidic TFE has a weaker hydrogen bond interaction with silica, due to the fact that the alcohols serve as hydrogen bond acceptors. The experiment shows that EtOH and TFE have nearly identical surface layer viscosities, originating from the differences in hydrogen bonding with the silica surface. Confinement was found to have little effect on the internal rotation of terminal CF{sub 3} or CH{sub 3} groups. 32 refs., 2 figs., 3 tabs.

  5. Substrate effect on nanoporous structure of silica wires by channel-confined self-assembly of block-copolymer and sol-gel precursors

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hu, Michael Z.; Lai, Peng

    2015-01-01

    Nanoporous silica wires of various wire diameters were developed by space-confined molecular self-assembly of triblock copolymer ethylene/propylene/ethylene (P123) and silica alkoxide precursor (tetraethylorthosilicate, TEOS). Two distinctive hard-templating substrates, anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC), with channel diameters in the range between 10 nm and 200 nm were employed for space-confinement of soft molecular self-assembly driven by the block-copolymer microphase separation. It was observed in the scanning and transmission electron microscope (STEM) studies that the substrate geometry and material characteristics had pronounced effects on the structure and morphology of the silica nanowires. A substrate wall effect was proposed tomore » explain the ordering and orientation of the intra-wire mesostructure. Circular and spiral nanostructures were found only in wires formed in AAO substrate, not in EPC. Pore-size differences and distinctive wall morphologies of the nanowires relating to the substrates were discussed. It was shown that the material and channel wall characteristics of different substrates play key roles in the ordering and morphology of the intra-wire nanostructures.« less

  6. Substrate effect on nanoporous structure of silica wires by channel-confined self-assembly of block-copolymer and sol-gel precursors

    SciTech Connect (OSTI)

    Hu, Michael Z.; Lai, Peng

    2015-01-01

    Nanoporous silica wires of various wire diameters were developed by space-confined molecular self-assembly of triblock copolymer ethylene/propylene/ethylene (P123) and silica alkoxide precursor (tetraethylorthosilicate, TEOS). Two distinctive hard-templating substrates, anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC), with channel diameters in the range between 10 nm and 200 nm were employed for space-confinement of soft molecular self-assembly driven by the block-copolymer microphase separation. It was observed in the scanning and transmission electron microscope (STEM) studies that the substrate geometry and material characteristics had pronounced effects on the structure and morphology of the silica nanowires. A substrate wall effect was proposed to explain the ordering and orientation of the intra-wire mesostructure. Circular and spiral nanostructures were found only in wires formed in AAO substrate, not in EPC. Pore-size differences and distinctive wall morphologies of the nanowires relating to the substrates were discussed. It was shown that the material and channel wall characteristics of different substrates play key roles in the ordering and morphology of the intra-wire nanostructures.

  7. Studies of n-butane conversion over silica-supported platinum, platinum-silver and platinum-copper catalysts

    SciTech Connect (OSTI)

    Gu, Junhua

    1992-06-09

    The present work was undertaken to elucidate effect of adding silver and copper to silica-supported platinum catalyst on the activity and selectivity in the n-butane reactions. At the conditions of this study n-butane underwent both hydrogenolysis and structural isomerization. The catalytic activity and selectivities between hydrogenolysis and isomerization and within hydrogenolysis were measured at temperature varying from 330 C to 370 C. For platinum-silver catalysts, at lower temperatures studied the catalytic activity per surface platinum atom (turnover frequency) remained constant at lower silver content (between 0 at. % and 30 at. %) and decreased with further increased silver loading, suggesting that low- index planes could be dominant in the hydrogenolysis of n-butane. Moreover, increasing silver content resulted in an enhancement of the selectivity of isomerization products relative to hydrogenolysis products. At the higher temperature studied, no suppression in catalytic activity was observed. It is postulated that surface structure could change due to the mobility of surface silver atoms, leading to surface silver atoms forming islands or going to the bulk, and leaving large portions of basal planes exposed with active platinum atoms. It is also suggested that the presence of inert silver atoms results in weakening of the H-surface bond. This results in increased mobility of hydrogen atoms on the surface and hence, higher reactivity with other adsorbed species. For platinum copper catalysts, the mixed ensembles could play an active role in the hydrogenolysis of n-butane.

  8. Silanol-assisted carbinolamine formation in an amine-functionalized mesoporous silica surface: Theoretical investigation by fragmentation methods

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    de Lima Batista, Ana P.; Zahariev, Federico; Slowing, Igor I.; Braga, Ataualpa A. C.; Ornellas, Fernando R.; Gordon, Mark S.

    2015-12-15

    The aldol reaction catalyzed by an amine-substituted mesoporous silica nanoparticle (amine-MSN) surface was investigated using a large molecular cluster model (Si392O958C6NH361) combined with the surface integrated molecular orbital/molecular mechanics (SIMOMM) and fragment molecular orbital (FMO) methods. Three distinct pathways for the carbinolamine formation, the first step of the amine-catalyzed aldol reaction, are proposed and investigated in order to elucidate the role of the silanol environment on the catalytic capability of the amine-MSN material. The computational study reveals that the most likely mechanism involves the silanol groups actively participating in the reaction, forming and breaking covalent bonds in the carbinolamine step.more » Furthermore, the active participation of MSN silanol groups in the reaction mechanism leads to a significant reduction in the overall energy barrier for the carbinolamine formation. In addition, a comparison between the findings using a minimal cluster model and the Si392O958C6NH361 cluster suggests that the use of larger models is important when heterogeneous catalysis problems are the target.« less

  9. Time-Resolved Imaging of Material Response Following Laser-Induced Breakdown in the Bulk and Surface of Fused Silica

    SciTech Connect (OSTI)

    Raman, R N; Negres, R A; DeMange, P; Demos, S G

    2010-02-04

    Optical components within high energy laser systems are susceptible to laser-induced material modification when the breakdown threshold is exceeded or damage is initiated by pre-existing impurities or defects. These modifications are the result of exposure to extreme conditions involving the generation of high temperatures and pressures and occur on a volumetric scale of the order of a few cubic microns. The response of the material following localized energy deposition, including the timeline of events and the individual processes involved during this timeline, is still largely unknown. In this work, we investigate the events taking place during the entire timeline in both bulk and surface damage in fused silica using a set of time-resolved microscopy systems. These microscope systems offer up to 1 micron spatial resolution when imaging static or dynamic effects, allowing for imaging of the entire process with adequate temporal and spatial resolution. These systems incorporate various pump-probe geometries designed to optimize the sensitivity for detecting individual aspects of the process such as the propagation of shock waves, near-surface material motion, the speed of ejecta, and material transformations. The experimental results indicate that the material response can be separated into distinct phases, some terminating within a few tens of nanoseconds but some extending up to about 100 microseconds. Overall the results demonstrate that the final characteristics of the modified region depend on the material response to the energy deposition and not on the laser parameters.

  10. Parametric study of the damage ring pattern in fused silica induced by multiple longitudinal modes laser pulses

    SciTech Connect (OSTI)

    Chambonneau, M. Grua, P.; Rullier, J.-L.; Lamaignère, L.; Natoli, J.-Y.

    2015-03-14

    With the use of multiple longitudinal modes nanosecond laser pulses at 1064 nm, laser damage sites at the exit surface of fused silica clearly and systematically exhibit ring patterns. It has been shown in our previous works that the apparent chronology of rings was closely related to the temporal shape of the laser pulses. This particular correspondence had suggested an explanation of the ring morphology formation based on the displacement of an ionization front in the surrounding air. To provide a former basis for this hypothesis and deeper understanding of ring pattern formation, additional experiments have been performed. First, the impact of fluence has been investigated, revealing that a wide variety of damage sites are produced within a very narrow fluence range; this fact involves the chronology of appearance of a surface plasma during the laser pulse. The sizes of the damage sites are proportional to the fluence of their expansion occurring between the beginning of the plasma and the end of the laser pulse. Second, specific experiments have been carried out at different angles of incidence, resulting in egg-shaped patterns rather than circular ones. This behavior can be explained by our previous hypothesis of creation of a plasma in air, its expansion being tightly conditioned by the illumination angle. This series of experiments, in which the angle of incidence is varied up to 80°, permits us to link quantitatively the working hypothesis of ionization front propagation with theoretical hydrodynamics modeling.

  11. Silanol-assisted carbinolamine formation in an amine-functionalized mesoporous silica surface: Theoretical investigation by fragmentation methods

    SciTech Connect (OSTI)

    de Lima Batista, Ana P.; Zahariev, Federico; Slowing, Igor I.; Braga, Ataualpa A. C.; Ornellas, Fernando R.; Gordon, Mark S.

    2015-12-15

    The aldol reaction catalyzed by an amine-substituted mesoporous silica nanoparticle (amine-MSN) surface was investigated using a large molecular cluster model (Si392O958C6NH361) combined with the surface integrated molecular orbital/molecular mechanics (SIMOMM) and fragment molecular orbital (FMO) methods. Three distinct pathways for the carbinolamine formation, the first step of the amine-catalyzed aldol reaction, are proposed and investigated in order to elucidate the role of the silanol environment on the catalytic capability of the amine-MSN material. The computational study reveals that the most likely mechanism involves the silanol groups actively participating in the reaction, forming and breaking covalent bonds in the carbinolamine step. Furthermore, the active participation of MSN silanol groups in the reaction mechanism leads to a significant reduction in the overall energy barrier for the carbinolamine formation. In addition, a comparison between the findings using a minimal cluster model and the Si392O958C6NH361 cluster suggests that the use of larger models is important when heterogeneous catalysis problems are the target.

  12. Ultralow-threshold laser and blue shift cooperative luminescence in a Yb{sup 3+} doped silica microsphere

    SciTech Connect (OSTI)

    Huang, Yantang Huang, Yu; Zhang, Peijin; Guo, Changlei; Department of Electronic Engineering, Institute of Optoelectronic Technology, Xiamen University, Xiamen, 361005

    2014-02-15

    An experimental investigation on ultralow threshold laser and blue shift cooperative luminescence (CL) in a Yb{sup 3+} doped silica microsphere (YDSM) with continuous-wave 976 nm laser diode pumping is reported. The experimental results show that the YDSM emits laser oscillation with ultralow threshold of 2.62 ?W, and the laser spectrum is modulated by the microsphere morphology characteristics. In addition, blue emission of YDSM is also observed with the increase of pump power, which is supposed to be generated by CL of excited Yb ion-pairs with the absorption of 976 nm photons and Si-O vibration phonons, and the process is explained with an energy level diagram. This property of the blue shift CL with phonons absorption in the Yb{sup 3+}doped microcavity makes it attractive for the application of laser cooling based on anti-Stokes fluorescence emission, if the Yb{sup 3+}doped microcavity made from with low phonon energy host materials.

  13. Monitoring Phase Behavior of Sub- and Supercritical CO2 Confined in Porous Fractal Silica with 85% Porosity

    SciTech Connect (OSTI)

    Melnichenko, Yuri B; Mayama, Dr Hiroyuki; Cheng, Gang; Cheng, Gang; Blach, Tomasz P

    2010-01-01

    Phase behavior of CO{sub 2} confined in porous fractal silica with volume fraction of SiO{sub 2} {phi}{sub 5} = 0.15 was investigated using small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques. The range of fluid densities (0 < ({rho}{sub CO{sub 2}}){sub bulk} < 0.977 g/cm{sup 3}) and temperatures (T = 22 C, 35 and 60 C) corresponded to gaseous, liquid, near critical and supercritical conditions of the bulk fluid. The results revealed formation of a dense adsorbed phase in small pores with sizes D < 40 {angstrom} at all temperatures. At low pressure (P < 55 bar, ({rho}{sub CO{sub 2}}){sub bulk} < 0.2 g/cm{sup 3}) the average fluid density in pores may exceed the density of bulk fluid by a factor up to 6.5 at T = 22 C. This 'enrichment factor' gradually decreases with temperature, however significant fluid densification in small pores still exists at temperature T = 60 C, i.e., far above the liquid?gas critical temperature of bulk CO{sub 2} (T{sub c} = 31.1 C). Larger pores are only partially filled with liquid-like adsorbed layer which coexists with unadsorbed fluid in the pore core. With increasing pressure, all pores become uniformly filled with the fluid, showing no measurable enrichment or depletion of the porous matrix with CO{sub 2}.

  14. Laser damage by ns and sub-ps pulses on hafnia/silica anti-reflection coatings on fused silica double-sided polished using zirconia or ceria and washed with or without an alumina wash step.

    SciTech Connect (OSTI)

    Bellum, John Curtis; Rambo, Patrick K.; Schwarz, Jens; Kletecka, Damon; Atherton, Briggs W.; Kimmel, Mark W.; Smith, Ian Craig; Smith, Douglas; Hobbs, Zachary

    2010-10-01

    Sandia's Large Optics Coating Operation has extensive results of laser induced damage threshold (LIDT) testing of its anti-reflection (AR) and high reflection coatings on substrates pitch polished using ceria and washed in a process that includes an alumina wash step. The purpose of the alumina wash step is to remove residual polishing compound to minimize its role in laser damage. These LIDT tests are for multi longitudinal mode, ns class pulses at 1064 nm and 532 nm (NIF-MEL protocol) and mode locked, sub-ps class pulses at 1054 nm (Sandia measurements), and show reasonably high and adequate laser damage resistance for coatings in the beam trains of Sandia's Z-Backlighter terawatt and petawatt lasers. An AR coating in addition to coatings of our previous reports confirms this with LIDTs of 33.0 J/cm{sup 2} for 3.5 ns pulses and 1.8 J/cm{sup 2} for 350 fs pulses. In this paper, we investigate both ceria and zirconia in doublesided polishing (common for large flat Z-Backlighter laser optics) as they affect LIDTs of an AR coating on fused silica substrates washed with or without the alumina wash step. For these AR coated, double-sided polished surfaces, ceria polishing in general affords better resistance to laser damage than zirconia polishing and laser damage is less likely with the alumina wash step than without it. This is supported by specific results of laser damage tests with 3.5 ns, multi longitudinal mode, single shot pulses at 1064 nm and 532 nm, with 7.0 ns, single and multi longitudinal mode, single and multi shot pulses at 532 nm, and with 350 fs, mode-locked, single shot pulses at 1054 nm.

  15. Mass fractal characteristics of silica sonogels as determined by small-angle x-ray scattering and nitrogen adsorption

    SciTech Connect (OSTI)

    Donatti, D.A.; Vollet, D.R.; Ibanez Ruiz, A.; Mesquita, A.; Silva, T.F.P. [Unesp-Universidade Estadual Paulista, IGCE, Departamento de Fisica, P.O. Box 178 CEP, 13500-970 Rio Claro, Sao Paulo (Brazil)

    2005-01-01

    A sample series of silica sonogels was prepared using different water-tetraethoxysilane molar ratio (r{sub w}) in the gelation step of the process in order to obtain aerogels with different bulk densities after the supercritical drying. The samples were analyzed by means of small-angle x-ray-scattering (SAXS) and nitrogen-adsorption techniques. Wet sonogels exhibit mass fractal structure with fractal dimension D increasing from {approx}2.1 to {approx}2.4 and mass-fractal correlation length {xi} diminishing from {approx}13 nm to {approx}2 nm, as r{sub w} is changed in the nominal range from 66 to 6. The process of obtaining aerogels from sonogels and heat treatment at 500 deg. C, in general, increases the mass-fractal dimension D, diminishes the characteristic length {xi} of the fractal structure, and shortens the fractal range at the micropore side for the formation of a secondary structured particle, apparently evolved from the original wet structure at a high resolution level. The overall mass-fractal dimension D of aerogels was evaluated as {approx}2.4 and {approx}2.5, as determined from SAXS and from pore-size distribution by nitrogen adsorption, respectively. The fine structure of the 'secondary particle' developed in the obtaining of aerogels could be described as a surface-mass fractal, with the correlated surface and mass-fractal dimensions decreasing from {approx}2.4 to {approx}2.0 and from {approx}2.7 to {approx}2.5, respectively, as the aerogel bulk density increases from 0.25 (r{sub w}=66) up to 0.91 g/cm{sup 3} (r{sub w}=6)

  16. Particle Restabilization in Silica/PEG/Ethanol Suspensions: How Strongly do Polymers Need To Adsorb To Stabilize Against Aggregation?

    SciTech Connect (OSTI)

    Kim, So Youn; Zukoski, Charles F.

    2014-09-24

    We study the effects of increasing the concentration of a low molecular weight polyethylene glycol on the stability of 44 nm diameter silica nanoparticles suspended in ethanol. Polymer concentration, c{sub p}, is increased from zero to that characterizing the polymer melt. Particle stability is accessed through measurement of the particle second-virial coefficient, B{sub -2}, performed by light scattering and ultrasmall angle X-ray scattering (USAXS). The results show that at low polymer concentration, c{sub p} < 3 wt %, B{sub -2} values are positive, indicating repulsive interactions between particles. B{sub -2} decreases at intermediate concentrations (3 wt % < c{sub p} < 50 wt %), and particles aggregates are formed. At high concentrations (50 wt % < c{sub p}) B{sub -2} increases and stabilizes at a value expected for hard spheres with a diameter near 44 nm, indicating the particles are thermodynamically stable. At intermediate polymer concentrations, rates of aggregation are determined by measuring time-dependent changes in the suspension turbidity, revealing that aggregation is slowed by the necessity of the particles diffusing over a repulsive barrier in the pair potential. The magnitude of the barrier passes through a minimum at c{sub p} {approx} 12 wt % where it has a value of {approx}12kT. These results are understood in terms of a reduction of electrostatic repulsion and van der Waals attractions with increasing c{sub p}. Depletion attractions are found to play a minor role in particle stability. A model is presented suggesting displacement of weakly adsorbed polymer leads to slow aggregation at intermediate concentration, and we conclude that a general model of depletion restabilization may involve increased strength of polymer adsorption with increasing polymer concentration.

  17. In situ formation of sintered cordieritemullite nanomicro composites by utilizing of waste silica fume

    SciTech Connect (OSTI)

    Khattab, R.M.; EL-Rafei, A.M.; Zawrah, M.F.

    2012-09-15

    Highlights: ? We succeeded to obtain in situ formed sintered cordieritemullite nanomacro composites from waste and pure materials at 1400 C. ? Their sinterability was greatly dependent on both firing temperature and composition. ? XRD patterns showed that the optimum temperature required for formation of sintered cordieritemullite nanomacro composites was achieved at 1400 C. ? The batch containing 70 wt.% cordierite and 30 wt.% mullite exhibited the best properties. ? Microstructures of the densified composites were composed of nanomacro cordieritemullite structures. -- Abstract: This study aims at in situ formation of sintered cordieritemullite nanomacro composites having high technological properties using waste silica fume, calcined ball clay, calcined alumina, and magnesia as starting materials. The starting materials were mixed in different ratios to obtain different cordieritemullite composite batches in which the cordierite contents ranged from 50 to 100 wt.%. The batches were uni-axially pressed at 100 MPa and sintered at 1350, 1400 and 1450 C to select the optimum temperature required for cordieritemullite nanomacro composites formation. The formed phases were identified by X-ray diffraction (XRD) pattern. The sintering parameters in terms of bulk density (BD) and apparent porosity (AP) were determined. The microstructure of composites has been investigated by scanning electron microscope (SEM). Cold crushing strength (CCS) of the sintered batches was evaluated. The result revealed that the cordieritemullite nanomacro composites were in-situ formed at 1400 C. The batch containing 70 wt.% cordierite showed good physical and mechanical properties.

  18. Nature of =~SiOCrO(2)CI And (=~SiO)(2)CrO(2) Sites Prepared By Grafting CrO(2)CI(2) Onto Silica

    SciTech Connect (OSTI)

    Demmelmaier, C.A.; White, R.E.; Bokhoven, J.A.van; Scott, S.L.

    2009-05-14

    The room-temperature reaction between chromyl chloride and Sylopol 952 silicas pretreated at 200, 450, and 800 C was investigated using IR, XANES, and EXAFS spectroscopy, as well as by DFT modeling. On the silicas pretreated at 200 and 450 C, the structurally uniform sites formed by the reaction with one surface hydroxyl group are described as {triple_bond}SiOCrO{sub 2}Cl. Unreacted silanols persist on these silicas even in the presence of excess CrO{sub 2}Cl{sub 2}, and on the silica pretreated at 200 C some participate in hydrogen bonding with the grafted monochlorochromate sites. On the silica pretreated at 800 C, both {triple_bond}SiOCrO{sub 2}Cl and ({triple_bond}SiO){sub 2}CrO{sub 2} sites are formed. The latter are produced despite the absence of hydrogen-bonded hydroxyl pairs on the support. The origin of the chromate sites is proposed to be the reaction between CrO{sub 2}Cl{sub 2} and hydroxyl-substituted siloxane 2-rings. These rings are likely formed at 800 C by condensation between a pair of vicinal silanols in which one of the silanols is also a member of a geminal pair.

  19. An HRTEM investigation of the metastable low-temperature silica phase opal-CT in cherts and porcelanites from the Monterey Formation, CA

    SciTech Connect (OSTI)

    Cady, S.L.; Wenk, H.R. )

    1992-01-01

    High resolution transmission electron microscopy (HRTEM) is used to investigate the metastable low-temperature silica phase opal-CT in cherts and porcelanites from the Miocene Monterey Formation of California. Low-dose imaging techniques developed to image highly beam sensitive proteins were used in this study and have resulted in good phase contrast images of this hydrous silica phase. Detailed X-ray powder diffraction studies of stratigraphically equivalent rocks along the Santa Barbara coast indicate that the primary d-spacing of newly formed opal-CT differs in rocks with different ratios of silica and detrital minerals. Opal-CT forms progressively later and with a smaller primary d-spacing in rocks with increasing amounts of detrital minerals. In siliceous cherts opal-CT occurs as long needles that most often form dense spherulitic fiber bundles which are randomly dispersed within the rock matrix. The random orientation of fiber bundle nucleation centers does not appear to be associated with any obvious nucleation site, unlike the length-slow opal-CT fibers known as lussatite. Opal-CT needles produce optical diffractogram patterns that are compatible with tridymite and crystobalite. Streaking in the diffraction pattern of individual needles is attributed to a high density of planar defects parallel to their length. Planar defects are not as abundant in opal-CT needles formed in detrital-rich rocks suggesting the rapid growth of opal-CT in highly siliceous environments results in a greater proportion of stacking disorder in the needles. HRTEM provides a method for investigating the development of the microstructure of opal-CT during diagenesis.

  20. Near infrared radio-luminescence of O{sub 2} loaded radiation hardened silica optical fibers: A candidate dosimeter for harsh environments

    SciTech Connect (OSTI)

    Di Francesca, D.; Girard, S.; Boukenter, A.; Ouerdane, Y.; Agnello, S.; Gelardi, F. M.; Marcandella, C.; Paillet, P.

    2014-11-03

    We report on an experimental investigation of the infrared Radio-Luminescence (iRL) emission of interstitial O{sub 2} molecules loaded in radiation hardened pure-silica-core and fluorine-doped silica-based optical fibers (OFs). The O{sub 2} loading treatment successfully dissolved high concentrations of oxygen molecules into the silica matrix. A sharp luminescence at 1272 nm was detected when 2.5 cm of the treated OFs were irradiated with 10 keV X-rays. This emission originates from the radiative decay of the first excited singlet state of the embedded O{sub 2} molecules. The dose, dose-rate, and temperature dependencies of the infrared emission are studied through in situ optical measurements. The results show that the iRL is quite stable in doses of up to 1 MGy(SiO{sub 2}) and is linearly dependent on the dose-rate up to the maximum investigated dose-rate of ∼200 kGy(SiO{sub 2})/h. The temperature dependency of the iRL shows a decrease in efficiency above 200 °C, which is attributed to the non-radiative decay of the excited O{sub 2} molecules. The results obtained and the long-term stability of the O{sub 2}-loading treatment (no out-gassing effect) strongly suggest the applicability of these components to real-time remote dosimetry in environments characterized by high radiation doses and dose-rates.

  1. Detection of Amorphous Silica in Air-Oxidized Ti3SiC2 at 500-1000°C by NMR and SIMS

    SciTech Connect (OSTI)

    Pang, Wei Kong; Low, I M; Hanna, J V

    2010-11-12

    The use of secondary-ion mass spectrometry (SIMS), nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM) to detect the existence of amorphous silica in Ti3SiC2 oxidised at 500-1000 ºC is described. The formation of an amorphous SiO2 layer and its growth in thickness with temperature was monitored using dynamic SIMS. Results of NMR and TEM verify for the first time the direct evidence of amorphous silica formation during the oxidation of Ti3SiC2 at 1000 ºC.

  2. Preparation of magnetic photocatalyst nanoparticlesTiO{sub 2}/SiO{sub 2}/MnZn ferriteand its photocatalytic activity influenced by silica interlayer

    SciTech Connect (OSTI)

    Laohhasurayotin, Kritapas; Pookboonmee, Sudarat; Viboonratanasri, Duangkamon; Kangwansupamonkon, Wiyong

    2012-06-15

    Highlights: ? TiO{sub 2}/SiO{sub 2}/MnZn ferrite acts as magnetic photocatalyst nanoparticle. ? SiO{sub 2} interlayer is used to prevent electron migration between photocatalyst and magnetic core. ? TiO{sub 2}/MnZn ferrite without SiO{sub 2} interlayer shows poor magnetic and photocatalytic property. -- Abstract: A magnetic photocatalyst, TiO{sub 2}/SiO{sub 2}/MnZn ferrite, was prepared by stepwise synthesis involving the co-precipitation of MnZn ferrite as a magnetic core, followed by a coating of silica as the interlayer, and titania as the top layer. The particle size and distribution of magnetic nanoparticles were found to depend on the addition rate of reagent and dispersing rate of reaction. The X-ray diffractometer and transmission electron microscope were used to examine the crystal structures and the morphologies of the prepared composites. Vibrating sample magnetometer was also used to reveal their superparamagnetic property. The UVVis spectrophotometer was employed to monitor the decomposition of methylene blue in the photocatalytic efficient study. It was found that at least a minimum thickness of the silica interlayer around 20 nm was necessary for the inhibition of electron transference initiated by TiO{sub 2} and MnZn ferrite.

  3. Dynamics of Propane in Silica Mesopores Formed upon PropyleneHydrogenation over Pt Nanoparticles by Time-Resolved FT-IRSpectroscopy

    SciTech Connect (OSTI)

    Waslylenko, Walter; Frei, Heinz

    2007-01-31

    Propylene hydrogenation over Pt nanoparticles supported onmesoporous silica type SBA-15 was monitored by time-resolved FT-IRspectroscopy at 23 ms resolution using short propylene gas pulses thatjoined a continuous flow of hydrogen in N2 (1 atm total pressure).Experiments were conducted in the temperature range 323-413 K. Propanewas formed within 100 milliseconds or faster. The CH stretching regionrevealed distinct bands for propane molecules emerging inside thenanoscale channels of the silica support. Spectral analysis gave thedistribution of the propane product between support and surrounding gasphase as function of time. Kinetic analysis showed that the escape ofpropane molecules from the channels occurred within hundreds ofmilliseconds (3.1 + 0.4 s-1 at 383 K). A steady state distribution ofpropane between gas phase and mesoporous support is established as theproduct is swept from the catalyst zone by the continuous flow ofhydrogen co-reactant. This is the first direct spectroscopic observationof emerging products of heterogeneous catalysis on nanoporous supportsunder reaction conditions.

  4. Fluorinated silica microchannel surfaces

    DOE Patents [OSTI]

    Kirby, Brian J.; Shepodd, Timothy Jon

    2005-03-15

    A method for surface modification of microchannels and capillaries. The method produces a chemically inert surface having a lowered surface free energy and improved frictional properties by attaching a fluorinated alkane group to the surface. The coating is produced by hydrolysis of a silane agent that is functionalized with either alkoxy or chloro ligands and an uncharged C.sub.3 -C.sub.10 fluorinated alkane chain. It has been found that the extent of surface coverage can be controlled by controlling the contact time from a minimum of about 2 minutes to a maximum of 120 minutes for complete surface coverage.

  5. The use of Ahuachapan fluid chemistry to indicate natural state conditions and reservoir processes during exploitation

    SciTech Connect (OSTI)

    Treusdell, A.H. ); Aunzo, Z.; Bodvarsson, G. ); Alonso, J.; Campos, A. )

    1989-01-01

    Chemical analyses of production fluids from Ahuachapan, El Salvador, have been used to indicate natural state reservoir fluid temperatures and chloride concentrations and reservoir processes resulting from exploitation. Geothermometer temperatures (Na--K--Ca and SiO{sub 2}) and calculated aquifer Cl for early flows show a gradient from about 265{degree}C and 9000 ppM Cl in the western part of the well field to 235{degree}C and 6000 ppM Cl in the eastern part. The geochemical temperatures are 10--20{degree}C higher than early downhole measurements. Since exploitation started, pressures have declined over most of the drilled area with boiling and excess-enthalpy discharges in the eastern and western parts. In the center of the field, a number of wells show mixing with cooler, less-saline water. These wells are nearly coincident with a major NE-SW oriented fault that may be the conduit for downward recharge of cooler fluids from an overlying aquifer. 12 refs., 9 figs., 1 tab.

  6. I/S and C/S mixed layers, some indicators of recent physical-chemical changes in active geothermal systems: The case study of Chipilapa (El Salvador)

    SciTech Connect (OSTI)

    Beaufort, D.; Papapanagiotou, P.; patrier, P.; Fouillac, A.M.; Traineau, H.

    1996-01-24

    I/S and C/S mixed layers from the geothermal field of Chipilapa (El Salvador) have been studied in details in order to reevaluate their potential use as indicator of the thermodynamic conditions in which they were formed. It is funded that overprinting of clay bearing alteration stages is common. For a given alteration stage, the spatial variation of I/S and C/S mixed layer ininerals is controlled by kinetics of mixed layer transformation and not only by temperature. Clay geo-thermometers cannot give reliable results because the present crystal-chemical states of the I/S and C/S mixed layers is not their initial state, it was aquired during the overall hydrothermal history which post dated the nucleation of smectitic clay material at high temperature. Occurrences of smectites or smectite-rich mixed layers at high temperature in reservoirs is a promising guide for reconstruct the zones in which boiling or mixing of non isotherinal fluids occurred very recently or still presently.

  7. Water information bulletin No. 30 geothermal investigations in Idaho

    SciTech Connect (OSTI)

    Mitchell, J.C.; Johnson, L.L.; Anderson, J.E.; Spencer, S.G.; Sullivan, J.F.

    1980-06-01

    There are 899 thermal water occurrences known in Idaho, including 258 springs and 641 wells having temperatures ranging from 20 to 93/sup 0/C. Fifty-one cities or towns in Idaho containing 30% of the state's population are within 5 km of known geothermal springs or wells. These include several of Idaho's major cities such as Lewiston, Caldwell, Nampa, Boise, Twin Falls, Pocatello, and Idaho Falls. Fourteen sites appear to have subsurface temperatures of 140/sup 0/C or higher according to the several chemical geothermometers applied to thermal water discharges. These include Weiser, Big Creek, White Licks, Vulcan, Roystone, Bonneville, Crane Creek, Cove Creek, Indian Creek, and Deer Creek hot springs, and Raft River, Preston, and Magic Reservoir areas. These sites could be industrial sites, but several are in remote areas away from major transportation and, therefore, would probably be best utilized for electrical power generation using the binary cycle or Magma Max process. Present uses range from space heating to power generation. Six areas are known where commercial greenhouse operations are conducted for growing cut and potted flowers and vegetables. Space heating is substantial in only two places (Boise and Ketchum) although numerous individuals scattered throughout the state make use of thermal water for space heating and private swimming facilities. There are 22 operating resorts using thermal water and two commercial warm-water fish-rearing operations.

  8. Apacheta, a new geothermal prospect in Northern Chile

    SciTech Connect (OSTI)

    Urzua, Luis; Powell, Tom; Cumming, William B.; Dobson, Patrick

    2002-05-24

    The discovery of two high-temperature fumaroles, with gas geochemistry compatible with an economic geothermal system, established Apacheta as one of the most attractive geothermal exploration prospects in northern Chile. These remote fumaroles at 5,150 m elevation were first sampled in 1999 by ENAP and its partners, following up on the reports of a CODELCO water exploration well that flowed small amounts of dry steam at 4,540 m elevation in the valley 4.5 km east of the fumaroles. The prospect is associated with a Plio-Pleistocene volcanic complex located within a NW-trending graben along the axis of the high Andes. The regional water table is 4,200 masl. There are no hot springs, just the 88 degrees C steam well and the 109 degrees and 118 degrees C fumaroles with gas compositions that indicate reservoir temperatures of greater than or equal to 250 degrees C, using a variety of gas geothermometers. An MT-TDEM survey was completed in 2001-2002 by Geotermica del Norte (SDN), an ENAP-C ODELCO partnership, to explore the Apacheta geothermal concession. The survey results indicated that base of the low resistivity clay cap has a structural apex just west of the fumaroles, a pattern typically associated with shallow permeability within a high temperature geothermal resource. SGN plans to drill at least one exploration well in 2002-03 to characterize a possible economic resource at Apacheta.

  9. Hydrology and geochemistry of thermal ground water in southwestern Idaho and north-central Nevada

    SciTech Connect (OSTI)

    Young, H.W.; Lewis, R.E.

    1982-01-01

    Chemical analyses of water from 12 wells and 9 springs indicate that nonthermal waters are a calcium bicarbonate type; thermal waters are a sodium carbonate or bicarbonate type. Chemical geothermometers indicate probable maximum reservoir temperatures are near 100/sup 0/ Celsius. Concentration of tritium in the thermal water is near zero. Depletion of stable isotopes in the hot waters relative to present-day meteoric waters indicates recharge to the system probably occurred when the climate averaged 3/sup 0/ to 5/sup 0/ Celsius colder than at present. Temperatures about 3.5/sup 0/ Celsius colder than at present occurred during periods of recorded Holocene glacial advances and indicate a residence time of water in the system of at least several thousand years. Residence time calculated on the basis of reservoir volume and thermal-water discharge is 3400 to 6800 years for an effective reservoir porosity of 0.05 and 0.10, respectively. Preliminary analyses of carbon-14 determinations indicate an age of the hot waters of about 18,000 to 25,000 years. The proposed conceptual model for the area is one of an old system, where water has circulated for thousands, even tens of thousands, of years. Within constraints imposed by the model described, reservoir thermal energy for the geothermal system in southwestern Idaho and north-central Nevada is about 130 x 10/sup 18/ calories.

  10. BACA Project: geothermal demonstration power plant. Final report

    SciTech Connect (OSTI)

    Not Available

    1982-12-01

    The various activities that have been conducted by Union in the Redondo Creek area while attempting to develop the resource for a 50 MW power plant are described. The results of the geologic work, drilling activities and reservoir studies are summarized. In addition, sections discussing the historical costs for Union's involvement with the project, production engineering (for anticipated surface equipment), and environmental work are included. Nineteen geothermal wells have been drilled in the Redondo Creek area of the Valles Caldera: a prominent geologic feature of the Jemez mountains consisting of Pliocene and Pleistocene age volcanics. The Redondo Creek area is within a complex longitudinal graben on the northwest flank of the resurgent structural dome of Redondo Peak and Redondo Border. The major graben faults, with associated fracturing, are geologically plausible candidates for permeable and productive zones in the reservoir. The distribution of such permeable zones is too erratic and the locations too imprecisely known to offer an attractive drilling target. Log analysis indicates there is a preferred mean fracture strike of N31W in the upper portion of Redondo Creek wells. This is approximately perpendicular to the major structure in the area, the northeast-striking Redondo Creek graben. The geothermal fluid found in the Redondo Creek reservoir is relatively benign with low brine concentrations and moderate H/sub 2/S concentrations. Geothermometer calculations indicate that the reservoir temperature generally lies between 500/sup 0/F and 600/sup 0/F, with near wellbore flashing occurring during the majority of the wells' production.

  11. Salt effects on isotope partitioning and their geochemical implications: An overview

    SciTech Connect (OSTI)

    Horita, J.; Cole, D.R.; Fortier, S.M.

    1996-01-01

    Essential to the use of stable isotopes as natural tracers and geothermometers is the knowledge of equilibrium isotope partitioning between different phases and species, which is usually a function of temperature only. The one exception known to date is oxygen and hydrogen isotope fractionation between liquid water and other phases (steam, gases, minerals), which changes upon the addition of salts to water, i.e., the isotope salt salt effect. Our knowledge of this effect, the difference between activity and composition (a-X) of isotopic water molecules in salt solutions, is very limited and controversial, especially at elevated temperatures. For the last several years, we have been conducting a detailed, systematic experimental study at Oak Ridge National Laboratory to determine the isotope salt effects from room temperature to elevated temperatures (currently to 500{degree}C). From this effort, a simple, coherent picture of the isotope salt effect is emerging, that differs markedly from the complex results reported in the literature. In this communication, we present an overview on the isotope salt effect, obtained chiefly from our study. Observed isotope salt effects in salt solutions are significant even at elevated temperatures. The importance and implications of the isotope salt effect for isotopic studies of brine-dominated systems are also discussed in general terms.

  12. Stable photoluminescence of zinc oxide quantum dots in silica nanoparticles matrix prepared by the combined sol{endash}gel and spray drying method

    SciTech Connect (OSTI)

    Mikrajuddin; Iskandar, F.; Okuyama, K.; Shi, F. G.

    2001-06-01

    A sol{endash}gel method was employed to produce a zinc oxide (ZnO) colloid consisting of ZnO nanocrystalline particles with an average diameter of {similar_to}3 nm, and subsequently mixed with a silica (SiO{sub 2}) colloid. The mixture was finally spray dried to form a powder nanocomposite. It was found that the green photoluminescence (PL) exhibited by the composite was very stable: the intensity, position, and shape do not change even after being aged over 30 days. Thus, the ZnO/SiO{sub 2} nanocomposite has a much improved PL stability over ZnO colloids, which is often found to undergo a significant redshift even after aging over a few days. Our results are expected to have significant technological implications. {copyright} 2001 American Institute of Physics.

  13. Time-resolved x-ray imaging of high-power laser-irradiated under-dense silica aerogels and agar foams

    SciTech Connect (OSTI)

    Koch, J.A.; Estabrook, K.G.; Bauer, J.D. [and others

    1995-08-01

    This paper presents the results of experiments in which a high-power laser was used to irradiate low density (4 - 9 mg/cm{sup 3}) silica aerogel and agar foam targets. The laser-solid interaction and energy transport through the material were monitored with time-resolved imaging diagnostics, and the data show the production and propagation of an x-ray emission front in the plasma. The emission-front trajectory data are found to be in significant disagreement with detailed simulations, which predict a much more rapid heating of the cold material, and the data suggest that this discrepancy is not explainable by target inhomogeneities. Evidence suggests that energy transport into the cold material may be dominated by thermal conduction; however, no completely satisfactory explanation for the discrepancies is identified, and further experimental and theoretical research is necessary in order to resolve this important problem in laser-plasma interaction physics.

  14. The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces

    SciTech Connect (OSTI)

    Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W

    2009-10-29

    Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as {tau}{sup 0.3} for sites in the 50-100 {micro}m size range.

  15. Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization

    SciTech Connect (OSTI)

    Lafon, Olivier; Thankamony, Aany S. Lilly; Kokayashi, Takeshi; Carnevale, Diego; Vitzthum, Veronika; Slowing, Igor I.; Kandel, Kapil; Vezin, Herve; Amoureux, Jean-Paul; Bodenhausen, Geoffrey; Pruski, Marek

    2012-12-21

    We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements ?on/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to ?on/off ? 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.

  16. Determination of structure and phase transition of light element nanocomposites in mesoporous silica: case study of NH3BH3 in MCM-41

    SciTech Connect (OSTI)

    Kim, Hyun Jeong; Karkamkar, Abhijeet J.; Autrey, Thomas; Chupas, Peter; Proffen, Thomas E.

    2009-09-30

    The structure of ammonia borane (AB), NH3BH3, infused in mesoporous silica MCM-41 and its evolution over the temperature range of 80 to 300 K was investigated using the atomic pair distribution function (PDF) analysis of synchrotron X-ray powder diffraction data in order to understand the origin of improved dehydrogenation properties of the system. Our study shows how X-ray PDF analysis can be used to elucidate the structure of light guest species loaded in mesoporous silica materials despite of its low scattering power of composed elements (N, B, and H) compared to its host (SiO2). PDF analyses of two AB-loaded compositions with weight ratio AB:MCM-41=1:1 and 3:1 provide a strong evidence that AB aggregate, previously found in AB:MCM-41?1:1 samples, is same species as neat AB. For both of them an orthorhombic to tetragonal structural phase transition occurs at 225 K on warming. On the other hand, AB residing inside meso-pores, which is found in AB:MCM-41=1:2 sample, does not undergo such phase transition. It rather stays in tetragonal phase over a wide temperature range of 110 to 240 K and starts to lose structural correlation above 240 K. This strongly suggests that nano-confinement of AB inside meso-pores stabilizes high temperature tetragonal phase at much lower temperature. These results provide important clues to two critical questions: why nan-compositions of AB leads dehydrogenation to lower temperature and why the neat AB like propoerties are recovered at high AB loading samples. This work was supported by the US Department of Energy Office of Basic Energy Sciences, Chemical Sciences program. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  17. Characterisation of amorphous silica in air-oxidised Ti3SiC2 at 500-1000 °C using secondary-ion mass spectrometry, nuclear magnetic resonance and transmission electron microscopy

    SciTech Connect (OSTI)

    Pang, W K; Low, I M; Hanna, J V

    2010-05-18

    In this paper we have described the use of secondary-ion mass spectrometry (SIMS), solid state {sup 29}Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM) to detect the existence of amorphous silica in Ti{sub 3}SiC{sub 2} oxidised at 500-1000 C. The formation of amorphous SiO{sub 2} and growth of crystalline TiO{sub 2} with temperature was monitored using dynamic SIMS and synchrotron radiation diffraction. A duplex structure with an outer TiO{sub 2}-rich layer and an inner mixed layer of SiO{sub 2} and TiO{sub 2} was observed. Results of NMR and TEM verified for the first time the direct evidence of amorphous silica formation during the oxidation of Ti{sub 3}SiC{sub 2} at the temperature range 500-1000 C.

  18. Research and Development of a New Silica-Alumina Based Cementitious Material Largely Using Coal Refuse for Mine Backfill, Mine Sealing and Waste Disposal Stabilization

    SciTech Connect (OSTI)

    Henghu Sun; Yuan Yao

    2012-06-29

    Coal refuse and coal combustion byproducts as industrial solid waste stockpiles have become great threats to the environment. To activate coal refuse is one practical solution to recycle this huge amount of solid waste as substitute for Ordinary Portland Cement (OPC). The central goal of this project is to investigate and develop a new silica-alumina based cementitious material largely using coal refuse as a constituent that will be ideal for durable construction, mine backfill, mine sealing and waste disposal stabilization applications. This new material is an environment-friendly alternative to Ordinary Portland Cement. The main constituents of the new material are coal refuse and other coal wastes including coal sludge and coal combustion products (CCPs). Compared with conventional cement production, successful development of this new technology could potentially save energy and reduce greenhouse gas emissions, recycle vast amount of coal wastes, and significantly reduce production cost. A systematic research has been conducted to seek for an optimal solution for enhancing pozzolanic reactivity of the relatively inert solid waste-coal refuse in order to improve the utilization efficiency and economic benefit as a construction and building material.

  19. Methanol Decomposition over Palladium Particles Supported on Silica: Role of Particle Size and Co-Feeding Carbon Dioxide on the Catalytic Properties

    SciTech Connect (OSTI)

    Hokenek, Selma; Kuhn, John N. (USF)

    2012-10-23

    Monodisperse palladium particles of six distinct and controlled sizes between 4-16 nm were synthesized in a one-pot polyol process by varying the molar ratios of the two palladium precursors used, which contained palladium in different oxidation states. This difference permitted size control by regulation of the nucleation rate because low oxidation state metals ions nucleate quickly relative to high oxidation state ions. After immobilization of the Pd particles on silica by mild sonication, the catalysts were characterized by X-ray absorption spectroscopy and applied toward catalytic methanol decomposition. This reaction was determined as structure sensitive with the intrinsic activity (turnover frequency) increasing with increasing particle size. Moreover, observed catalytic deactivation was linked to product (carbon monoxide) poisoning. Co-feeding carbon dioxide caused the activity and the amount of deactivation to decrease substantially. A reaction mechanism based on the formation of the {pi}-bond between carbon and oxygen as the rate-limiting step is in agreement with antipathetic structure sensitivity and product poisoning by carbon monoxide.

  20. Modifications under irradiation of a self-assembled monolayer grafted on a nano-porous silica glass: a solid-state NMR characterization

    SciTech Connect (OSTI)

    Le Caer, S.; Chatelain, C.; Renault, J.Ph.; Brunet, F.; Charpentier, T.; Durand, D.; Dauvois, V.

    2012-02-15

    Controlled pore glasses with a pore size of 8 nm are grafted with chlorodimethylsilane (ClSi(CH{sub 3}){sub 2}H). The surface of the glass is carefully characterized before and after irradiation with 10 MeV electrons by solid-state NMR measurements. {sup 1}H MAS NMR experiments in one and two dimensions (2D double quantum and 2D exchange) have been used to reveal the grafting of the chlorodimethylsilane at the silica surface and evidence the formation of a homogeneous layer on the surface. Irradiation leads to a high H{sub 2} yield (3.3 * 10{sup -7} mol/J) due to the efficient cleavage of the Si H bond. Methane is detected in smaller quantities (5.5 * 10{sup -8} mol/J), indicating that the Si-H bond is preferentially cleaved over the Si-C bond. The H{sub 2} production arising from OH groups on the surface is very minor in comparison to the S- H and Si-C radiolysis. (authors)

  1. GRIZZLY Model of Multi-Reactive Species Diffusion, Moisture/Heat Transfer and Alkali-Silica Reaction for Simulating Concrete Aging and Degradation

    SciTech Connect (OSTI)

    Huang, Hai; Spencer, Benjamin W.; Cai, Guowei

    2015-09-01

    Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear power plants for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have accurate and reliable predictive tools to address concerns related to various aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to document the progress of the development and implementation of a fully coupled thermo-hydro-mechanical-chemical model in GRIZZLY code with the ultimate goal to reliably simulate and predict long-term performance and response of aged NPP concrete structures subjected to a number of aging mechanisms including external chemical attacks and volume-changing chemical reactions within concrete structures induced by alkali-silica reactions and long-term exposure to irradiation. Based on a number of survey reports of concrete aging mechanisms relevant to nuclear power plants and recommendations from researchers in concrete community, we’ve implemented three modules during FY15 in GRIZZLY code, (1) multi-species reactive diffusion model within cement materials; (2) coupled moisture and heat transfer model in concrete; and (3) anisotropic, stress-dependent, alkali-silica reaction induced swelling model. The multi-species reactive diffusion model was implemented with the objective to model aging of concrete structures subjected to aggressive external chemical attacks (e.g., chloride attack, sulfate attack, etc.). It considers multiple processes relevant to external chemical attacks such as diffusion of ions in aqueous phase within pore spaces, equilibrium chemical speciation reactions and kinetic mineral dissolution/precipitation. The moisture/heat transfer module was implemented to simulate long-term spatial and temporal evolutions of the moisture and temperature fields within concrete structures at both room and elevated temperatures. The ASR swelling model implemented in GRIZZLY code can simulate anisotropic expansions of ASR gel under either uniaxial, biaxial and triaxial stress states, and can be run simultaneously with the moisture/heat transfer model and coupled with various elastic/inelastic solid mechanics models that were implemented in GRIZZLY code previously. This report provides detailed descriptions of the governing equations, constitutive equations and numerical algorithms of the three modules implemented in GRIZZLY during FY15, simulation results of example problems and model validation results by comparing simulations with available experimental data reported in the literature. The close match between the experiments and simulations clearly demonstrate the potential of GRIZZLY code for reliable evaluation and prediction of long-term performance and response of aged concrete structures in nuclear power plants.

  2. A STUDY OF FISCHER 344 RATS EXPOSED TO SILICA DUST AT CONCENTRATIONS OF 0, 2, 10 OR 20 MG/M3, THEN MAINTAINED FOR SIX MONTHS PRIOR TO ASSESSMENT.

    SciTech Connect (OSTI)

    KUTZMAN,R.S.

    1984-11-01

    The major objective of this study was to relate the results of a series of functional tests to the compositional and structural alterations in the rat lung induced by subchronic exposure to silica dust. To induce a fibrotic lesion, Fischer-344 rats were exposed to either 0, 2, 10, or 20 mg Si0{sub 2}/m{sup 3} for 6 hours/day, 5 days/week for six months and then maintained in an animal room, equipped with a laminar flow unit, for six months prior to assessment of the end points.

  3. Fluid diversion and sweep improvement with chemical gels in oil recovery processes. [Four types of gels: resorcinol-formaldehyde; colloidal silica; Cr sup 3+ (chloride)-xanthan; and Cr sup 3+ (acetate)-polyacrylamide

    SciTech Connect (OSTI)

    Seright, R.S.; Martin, F.D.

    1992-09-01

    The objectives of this project were to identify the mechanisms by which gel treatments divert fluids in reservoirs and to establish where and how gel treatments are best applied. Several different types of gelants were examined, including polymer-based gelants, a monomer-based gelant, and a colloidal-silica gelant. This research was directed at gel applications in water injection wells, in production wells, and in high-pressure gas floods. The work examined how the flow properties of gels and gelling agents are influenced by permeability, lithology, and wettability. Other goals included determining the proper placement of gelants, the stability of in-place gels, and the types of gels required for the various oil recovery processes and for different scales of reservoir heterogeneity. During this three-year project, a number of theoretical analyses were performed to determine where gel treatments are expected to work best and where they are not expected to be effective. The most important, predictions from these analyses are presented. Undoubtedly, some of these predictions will be controversial. However, they do provide a starting point in establishing guidelines for the selection of field candidates for gel treatments. A logical next step is to seek field data that either confirm or contradict these predictions. The experimental work focused on four types of gels: (1) resorcinol-formaldehyde, (2) colloidal silica, (3) Cr{sup 3+}(chloride)-xanthan, and (4) Cr{sup 3+}(acetate)-polyacrylamide. All experiments were performed at 41{degrees}C.

  4. Phosphine-stabilised Au{sub 9} clusters interacting with titania and silica surfaces: The first evidence for the density of states signature of the support-immobilised cluster

    SciTech Connect (OSTI)

    Andersson, Gunther G. E-mail: vladimir.golovko@canterbury.ac.nz Al Qahtani, Hassan S.; Golovko, Vladimir B. E-mail: vladimir.golovko@canterbury.ac.nz; Alvino, Jason F.; Bennett, Trystan; Wrede, Oliver; Mejia, Sol M.; Metha, Gregory F. E-mail: vladimir.golovko@canterbury.ac.nz; Adnan, Rohul; Gunby, Nathaniel; Anderson, David P.

    2014-07-07

    Chemically made, atomically precise phosphine-stabilized clusters Au{sub 9}(PPh{sub 3}){sub 8}(NO{sub 3}){sub 3} were deposited on titania and silica from solutions at various concentrations and the samples heated under vacuum to remove the ligands. Metastable induced electron spectroscopy was used to determine the density of states at the surface, and X-ray photoelectron spectroscopy for analysing the composition of the surface. It was found for the Au{sub 9} cluster deposited on titania that the ligands react with the titania substrate. Based on analysis using the singular value decomposition algorithm, the series of MIE spectra can be described as a linear combination of 3 base spectra that are assigned to the spectra of the substrate, the phosphine ligands on the substrate, and the Au clusters anchored to titania after removal of the ligands. On silica, the Au clusters show significant agglomeration after heat treatment and no interaction of the ligands with the substrate can be identified.

  5. Squeezing silica reveals meteorite secrets

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Spruce Up Your Home for Spring and Summer Spruce Up Your Home for Spring and Summer May 6, 2015 - 3:29pm Addthis Designing a landscape around your climate is key to maximizing energy-savings. | Photo courtesy of iStockphoto.com/RiverNorthPhotography Designing a landscape around your climate is key to maximizing energy-savings. | Photo courtesy of iStockphoto.com/RiverNorthPhotography Paige Terlip Paige Terlip Former Communicator, National Renewable Energy Laboratory What does this mean for me?

  6. Mixed-Matric Membranes for CO2 and H2 Gas Separations Using Metal-Organic Framework and Mesoporus Hybrid Silicas

    SciTech Connect (OSTI)

    Inga Musselman; Kenneth Balkus, Jr.; John Ferraris

    2009-01-07

    In this work, we have investigated the separation performance of polymer-based mixed-matrix membranes containing metal-organic frameworks and mesoporous hybrid silicas. The MOF/Matrimid{reg_sign} and MOP-18/Matrimid{reg_sign} membranes exhibited improved dispersion and mechanical strength that allowed high additive loadings with reduced aggregation, as is the case of the 80 wt% MOP-18/Matrimid{reg_sign} and the 80% (w/w) Cu-MOF/Matrimid{reg_sign} membranes. Membranes with up to 60% (w/w) ZIF-8 content exhibited similar mechanical strength and improved dispersion. The H{sub 2}/CO{sub 2} separation properties of MOF/Matrimid{reg_sign} mixed-matrix membranes was improved by either keeping the selectivity constant and increasing the permeability (MOF-5, Cu-MOF) or by improving both selectivity and permeability (ZIF-8). In the case of MOF-5/Matrimid{reg_sign} mixed-matrix membranes, the H{sub 2}/CO{sub 2} selectivity was kept at 2.6 and the H{sub 2} permeability increased from 24.4 to 53.8 Barrers. For the Cu-MOF/Matrimid{reg_sign} mixed-matrix membranes, the H{sub 2}/CO{sub 2} selectivity was kept at 2.05 and the H{sub 2} permeability increased from 17.1 to 158 Barrers. These two materials introduced porosity and uniform paths that enhanced the gas transport in the membranes. When ZIF-8/Matrimid{reg_sign} mixed-matrix membranes were studied, the H{sub 2}/CO{sub 2} selectivity increased from 2.9 to 4.4 and the permeability of H{sub 2} increased from 26.5 to 35.8 Barrers. The increased H{sub 2}/CO{sub 2} selectivity in ZIF-8/Matrimid{reg_sign} membranes was explained by the sieving effect introduced by the ZIF-8 crystals (pore window 0.34 nm) that restricted the transport of molecules larger than H{sub 2}. Materials with microporous and/or mesoporous cavities like carbon aerogel composites with zeolite A and zeolite Y, and membranes containing mesoporous ZSM-5 showed sieving effects for small molecules (e.g. H{sub 2} and CO{sub 2}), however, the membranes were most selective for CO{sub 2} due to the strong interaction of the zeolites with CO{sub 2}. For example, at 30 wt% ZSM-5 loading, the CO{sub 2}/CH{sub 4} selectivity increased from 34.7 (Matrimid{reg_sign}) to 56.4. The large increase in selectivity was the result of the increase in CO{sub 2} permeability from 7.3 (Matrimid{reg_sign}) to 14.6 Barrers. At 30 wt% ZSM-5 loading, the H{sub 2}/CH{sub 4} separation was also improved from 83.3 (Matrimid{reg_sign}) to 136.7 with an increase in H{sub 2} permeability from 17.5 (Matrimid{reg_sign}) to 35.3 Barrers. The 10% carbon aerogel-zeolite A and -zeolite Y composite/Matrimid{reg_sign} membranes exhibited an increase in the CO{sub 2}/CH{sub 4} separation from 34.7 to 71.5 (zeolite A composite) and to 57.4 (zeolite Y composite); in addition, the membrane exhibited an increase in the CO{sub 2}/N{sub 2} separation from 33.1 to 50 (zeolite A composite) and to 49.4 (zeolite Y composite), indicating that these type of materials have affinity for CO{sub 2}. The inclusion of mesoporosity enhanced the dispersion of the additive allowing loadings of up to 30% (w/w) without the formation of non-selective voids.

  7. Parametric study of a silica gel-water adsorption refrigeration cycle -- The influence of thermal capacitance and heat exchanger UA-values on cooling capacity, power density, and COP

    SciTech Connect (OSTI)

    Boelman, E.C.; Saha, B.B.; Kashiwagi, Takao

    1997-12-31

    The influence of heat exchanger UA-values (adsorber/desorber, evaporator, and condenser) is investigated for an adsorption chiller, with consideration given to the thermal capacitance of the adsorber/desorber by means of a lumped-parameter cycle simulation model developed by the authors and co-workers for the single-stage silica gel-water adsorption chiller. The closed-cycle-type chiller, for use in air conditioning, is driven by low-grade waste heat (85 C [185 F]) and cooled by water at 31 C (88 F) and operates on relatively short cycle times (420 seconds adsorption/desorption; 30 second adsorber/desorber sensible cooling and heating). The results showed cycle performance to be considerably affected by the thermal capacitance and UA-value of the adsorber/desorber, which is attributed to the severe sensible cooling/heating requirements resulting from batched cycle operation. The model is also sensitive to the evaporator UA-value--but to a lesser extent. The condenser UA-value is the least sensitive parameter due to the working pair adsorption behavior in the temperature range defined for desorption and condensation.

  8. Mechanisms of optical losses in the {sup 5}D{sub 4} and {sup 5}D{sub 3} levels in Tb{sup 3+} doped low silica calcium aluminosilicate glasses

    SciTech Connect (OSTI)

    Santos, J. F. M. dos; Terra, I. A. A.; Nunes, L. A. O.; Catunda, T.; Astrath, N. G. C.; Guimares, F. B.; Baesso, M. L.

    2015-02-07

    Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb{sup 3+}-doped low silica calcium aluminosilicate glasses are analyzed for UV (?{sub exc}?=?325?nm) and visible (488?nm) excitations. Under 325?nm excitation, the intensity of green luminescence increases proportionally to Tb{sup 3+} concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.515.0?wt. %. In the case of 488?nm excitation, a saturation behavior of the green emission is observed at intensities two orders of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325?nm and 488?nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb{sup 3+} concentrations. Cooperative upconversion from a pair of excited ions ({sup 5}D{sub 3}:{sup 5}D{sub 3} or {sup 5}D{sub 3}:{sup 5}D{sub 4}) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.

  9. Manufacturing complex silica aerogel target components

    SciTech Connect (OSTI)

    Defriend Obrey, Kimberly Ann [Los Alamos National Laboratory; Day, Robert D [Los Alamos National Laboratory; Espinoza, Brent F [Los Alamos National Laboratory; Hatch, Doug [Los Alamos National Laboratory; Patterson, Brian M [Los Alamos National Laboratory; Feng, Shihai [Los Alamos National Laboratory

    2008-01-01

    Aerogel is a material used in numerous components in High Energy Density Physics targets. In the past these components were molded into the proper shapes. Artifacts left in the parts from the molding process, such as contour irregularities from shrinkage and density gradients caused by the skin, have caused LANL to pursue machining as a way to make the components.

  10. Mesoporous Silica Nanomaterials for Applications in Catalysis...

    Office of Scientific and Technical Information (OSTI)

    horses have ability to deliver Doxorubicin to cancer cells and induce their death. ... was able to transfect cancer cell lines, such as human HeLa and CHO cancer cell lines. ...

  11. Method of synthesizing silica nanofibers using sound waves (Patent...

    Office of Scientific and Technical Information (OSTI)

    The method can be performed without heating or electrospinning, and instead includes less energy intensive strategies that can be scaled up to an industrial scale. The resulting ...

  12. Luminescent single-walled carbon nanotube/silica composite materials...

    Office of Scientific and Technical Information (OSTI)

    APA Chicago Bibtex Export Metadata Endnote Excel CSV XML Save to My Library Send to Email Send to Email Email address: Content: Close Send Cite: MLA Format Close Cite: APA ...

  13. Methods for globally treating silica optics to reduce optical damage

    DOE Patents [OSTI]

    Miller, Philip Edward; Suratwala, Tayyab Ishaq; Bude, Jeffrey Devin; Shen, Nan; Steele, William Augustus; Laurence, Ted Alfred; Feit, Michael Dennis; Wong, Lana Louie

    2012-11-20

    A method for preventing damage caused by high intensity light sources to optical components includes annealing the optical component for a predetermined period. Another method includes etching the optical component in an etchant including fluoride and bi-fluoride ions. The method also includes ultrasonically agitating the etching solution during the process followed by rinsing of the optical component in a rinse bath.

  14. Fluorescent single walled nanotube/silica composite materials

    DOE Patents [OSTI]

    Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

    2013-03-12

    Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.

  15. Fluorescent single walled nanotube/silica composite materials...

    Office of Scientific and Technical Information (OSTI)

    Authors: Dattelbaum, Andrew M. ; Gupta, Gautam ; Duque, Juan G. ; Doorn, Stephen K. ; Hamilton, Christopher E. ; DeFriend Obrey, Kimberly A. Publication Date: 2013-03-12 OSTI ...

  16. Effect of silica nanoparticles on morphology of segmented polyurethane...

    Office of Scientific and Technical Information (OSTI)

    Atomic force microscopy revealed a strong effect of nanoparticles on the large-scale ... Subject: 36 MATERIALS SCIENCE; ATOMIC FORCE MICROSCOPY; FILLERS; GLASS; MELTING; MELTING ...

  17. NEAR-IR TWO PHOTON MICROSCOPY IMAGING OF SILICA NANOPARTICLES...

    Office of Scientific and Technical Information (OSTI)

    with the preparation and characterization of similar molecular analogues by analytical techniques (IR, solution NMR, UV Vis, X ray crystallography) as well as DFT calculations. ...

  18. Compressed Silica Aerogels for the Study of Superfluid 3He

    SciTech Connect (OSTI)

    Pollanen, J.; Choi, H.; Davis, J. P.; Blinstein, S.; Lippman, T. M.; Halperin, W. P. [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Lurio, L. B. [Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States); Mulders, N. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

    2006-09-07

    We have performed Small Angle X-ray Scattering (SAXS) on uniaxially strained aerogels and measured the strain-induced structural anisotropy. We use a model to connect our SAXS results to anisotropy of the 3He quasiparticle mean free path in aerogel.

  19. Indium Phosphide Nanocrystals Formed in Silica by Sequential...

    Office of Scientific and Technical Information (OSTI)

    Affiliations Fisk University, Nashville, TN Northeast Normal University, Changchun, China ORNL North Carolina Central University, Durham Alabama A&M University, Normal...

  20. Synthesis of segmented silica rods by growth temperature regulation...

    Office of Scientific and Technical Information (OSTI)

    OSTI Identifier: 1115377 DOE Contract Number: DE-AC05-00OR22725 Resource Type: Journal Article Resource Relation: Journal Name: Angewandte Chemie International Edition; Journal ...

  1. Probing the Silica/Polysiloxane Interface: A Solid State NMR...

    Office of Scientific and Technical Information (OSTI)

    Resource Type: Journal Article Resource Relation: Journal ... Language: English Subject: 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 38 RADIATION ...

  2. Stable and responsive fluorescent carbon nanotube silica gels...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Conference: Spring 2010 Materials Research Society Meeting ; April 5, 2010 ; San Francisco, CA Research Org: Los Alamos National Laboratory (LANL) Sponsoring...

  3. Characterizing Radiation-Aged Polysiloxane-Silica Composites...

    Office of Scientific and Technical Information (OSTI)

    used effectively in the analysis of such materials and has ... of NMR observables that are based on basic polymer physics. ... decay associated with complex polymer networks. ...

  4. Probing warm dense silica with betatron radiation - Oral Presentation

    SciTech Connect (OSTI)

    Kotick, Jordan

    2015-08-24

    Laser wakefield acceleration (LWFA) has been shown to produce short X-ray pulses from oscillations of electrons within the plasma wake. These betatron X-rays pulses have a broad, synchrotron-like energy spectrum and a duration on the order of the driving laser pulse, thereby enabling probing of ultrafast interactions. Using the 1 J, 40fs short-pulse laser at the Matter in Extreme Conditions experimental station at LCLS, we have implemented LWFA to generate and subsequently characterized betatron X-rays. A scintillator and lanex screen were used to measure the charge fluence and energy spectrum of the produced electron beam.

  5. Characterizing Radiation-Aged Polysiloxane-Silica Composites...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Journal Name: Chemical ... ORGANIC, PHYSICAL AND ANALYTICAL ... CHEMISTRY; AGING; CHAINS; DECAY; MAGNETIZATION; NUCLEAR MAGNETIC RESONANCE; PHYSICS; ...

  6. Stable and responsive fluorescent carbon nanotube silica gels...

    Office of Scientific and Technical Information (OSTI)

    These results demonstrate a new route for the preparation of highly luminescent SWNTsilica composite materials that are potentially useful for future sensing applications. ...

  7. Luminescent single-walled carbon nanotube/silica composite materials...

    Office of Scientific and Technical Information (OSTI)

    Luminescent single-walled carbon nanotubesilica composite materials Citation Details In-Document Search Title: Luminescent single-walled carbon nanotubesilica composite materials ...

  8. Polyvinyl Chloride/Silica Nanoporous Composite Separator for All-Vanadium Redox Flow Battery Applications

    SciTech Connect (OSTI)

    Wei, Xiaoliang; Nie, Zimin; Luo, Qingtao; Li, Bin; Sprenkle, Vincent L.; Wang, Wei

    2013-04-22

    Redox flow batteries (RFBs) are capable of reversible conversion between electricity and chemical energy. Potential RFB applications resolve around mitigating the discrepancy between electricity production and consumption to improve the stability and utilization of the power infrastructure and tackling the intermittency of renewables such as photovoltaics or wind turbines to enable their reliable integration [1, 2]. Because the energy is stored in externally contained liquid electrolytes and the energy conversion reactions take place at the electrodes, RFBs hold a unique capability to separate energy and power and thus possess considerable design flexibility to meet either energy management driven or power rating oriented grid applications, which is considered to be a unparalleled advantage over conventional solid-state secondary batteries [3]. Other advantages of RFBs include fast response to load changes, high round-trip efficiency, long calender and cycle lives, safe operations, tolerance to deep discharge, etc. [4]. Among various flow battery chemistries, all-vanadium redox flow battery (VRB) was invented by Maria Skyllas-Kazacos at the University of New South Wales in the 1980s [5, 6] and have attracted substantial attention in both research and industrial communities today [7, 8]. A well-recognized advantage that makes VRB stands out among other redox chemistries is the reduced crossover contamination ascribed to employing four different oxidation states of the same vanadium element as the two redox couples. Recently, great progress has led to remarkably improved energy density of VRB by using sulfuric-chloric mixed acid supporting electrolytes that were stable at 2.5M vanadium and had wider operational temperature window of -5~50oC [9], compared with the traditional sulfuric acid VRB system [10].

  9. The effects of lithium hydroxide solution on alkali silica reaction gels created with opal

    SciTech Connect (OSTI)

    Mitchell, Lyndon D.; Beaudoin, James J.; Grattan-Bellew, Patrick

    2004-04-01

    The reaction of Nevada opal with calcium hydroxide, potassium hydroxide and lithium hydroxide solutions was investigated. In addition, opal was exposed to a combined solution of these three hydroxides. The progress of the three reactions was followed using X-ray diffraction (XRD), {sup 29}Si nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The XRD results indicated the presence of a low-angle peak exclusive to the lithium-based reactions. The NMR results suggested a change in the silicate structure in the presence of lithium. These techniques indicated that the reaction of the alkali with the opal starting material is inhibited and perhaps stopped in the presence of lithium hydroxide. SEM revealed that the morphology of the reaction products on the surface of the reacted opal grains is markedly different invariably. It was concluded that evidence to support the theory of a protective layer exists and that the nature of the layer varies with ion type.

  10. Method to prevent recession loss of silica and silicon-containing materials in combustion gas environments

    DOE Patents [OSTI]

    Brun, Milivoj Konstantin (Ballston Lake, NY); Luthra, Krishan Lal (Niskayuna, NY)

    2003-01-01

    While silicon-containing ceramics or ceramic composites are prone to material loss in combustion gas environments, this invention introduces a method to prevent or greatly reduce the thickness loss by injecting directly an effective amount, generally in the part per million level, of silicon or silicon-containing compounds into the combustion gases.

  11. The Effect of Foaming and Silica Dissolution on Melter Feed Rheology during Conversion to Glass

    SciTech Connect (OSTI)

    Marcial, Jose; Chun, Jaehun; Hrma, Pavel R.; Schweiger, Michael J.

    2014-11-23

    As the nuclear waste glass melter feed is converted to molten glass, the feed eventually becomes a continuous glass-forming melt in which dissolving refractory constituents are suspended together with numerous gas bubbles. Knowledge of mechanical properties of the melter feed is crucial for understanding the feed-to-glass conversion as it occurs in the cold cap. We measured the viscosity during heating of the feed and correlated it with the independently determined volume fractions of dissolving quartz particles and the gas phase. The measurement was performed with a rotating spindle rheometer on the melter feed heated at 5 K/min starting at several different temperatures. The effect of quartz particles, gas bubbles, and compositional inhomogeneity on the glass-forming melt viscosity was determined by fitting a linear relationship between log viscosity and volume fractions of suspended phases to data.

  12. Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen-Evolving Catalysts

    SciTech Connect (OSTI)

    Jiao, Feng; Frei, Heinz

    2009-01-01

    The development of integrated artificial photosynthetic systems for the direct conversion of carbon dioxide and water to fuel depends on the availability of efficient and robust catalysts for the chemical transformations. Catalysts need to exhibit turnover frequency (TOF) and density (hence size) commensurate with the solar flux at ground level (1000Wm2, airmass (AM) 1.5)[1]to avoid wasting of incidentsolar photons. For example, a catalyst with a TOF of 100 s1 requires a density of one catalytic site per square nanometer. Catalysts with lower rates or taking up a larger space will require a high-surface-area, nanostructured support that affords tens to hundreds of catalytic sites per square nanometer. Furthermore, catalysts need to operate close to the thermodynamic potential of the redox reaction so that amaximum fraction of the solar photon energy is converted to chemical energy. Stability considerations favor all-inorganic oxide materials, as does avoidance of harsh reaction conditions of pH value or temperature.

  13. Method for silicon carbide production by reacting silica with hydrocarbon gas

    DOE Patents [OSTI]

    Glatzmaier, G.C.

    1994-06-28

    A method is described for producing silicon carbide particles using a silicon source material and a hydrocarbon. The method is efficient and is characterized by high yield. Finely divided silicon source material is contacted with hydrocarbon at a temperature of 400 C to 1000 C where the hydrocarbon pyrolyzes and coats the particles with carbon. The particles are then heated to 1100 C to 1600 C to cause a reaction between the ingredients to form silicon carbide of very small particle size. No grinding of silicon carbide is required to obtain small particles. The method may be carried out as a batch process or as a continuous process. 5 figures.

  14. Method for silicon carbide production by reacting silica with hydrocarbon gas

    DOE Patents [OSTI]

    Glatzmaier, Gregory C.

    1994-01-01

    A method is described for producing silicon carbide particles using a silicon source material and a hydrocarbon. The method is efficient and is characterized by high yield. Finely divided silicon source material is contacted with hydrocarbon at a temperature of 400.degree. C. to 1000.degree. C. where the hydrocarbon pyrolyzes and coats the particles with carbon. The particles are then heated to 1100.degree. C. to 1600.degree. C. to cause a reaction between the ingredients to form silicon carbide of very small particle size. No grinding of silicon carbide is required to obtain small particles. The method may be carried out as a batch process or as a continuous process.

  15. Nanostructured electrocatalyst for fuel cells : silica templated synthesis of Pt/C composites.

    SciTech Connect (OSTI)

    Stechel, Ellen Beth; Switzer, Elise E.; Fujimoto, Cy H.; Atanassov, Plamen Borissov; Cornelius, Christopher James; Hibbs, Michael R.

    2007-09-01

    Platinum-based electrocatalysts are currently required for state-of-the-art fuel cells and represent a significant portion of the overall fuel cell cost. If fuel cell technology is to become competitive with other energy conversion technologies, improve the utilization of precious metal catalysts is essential. A primary focus of this work is on creating enhanced nanostructured materials which improve precious-metal utilization. The goal is to engineer superior electrocatalytic materials through the synthesis, development and investigation of novel templated open frame structures synthesized in an aerosol-based approach. Bulk templating methods for both Pt/C and Pt-Ru composites are evaluated in this study and are found to be limited due to the fact that the nanostructure is not maintained throughout the entire sample. Therefore, an accurate examination of structural effects was previously impossible. An aerosol-based templating method of synthesizing nanostructured Pt-Ru electrocatalysts has been developed wherein the effects of structure can be related to electrocatalytic performance. The aerosol-based templating method developed in this work is extremely versatile as it can be conveniently modified to synthesize alternative materials for other systems. The synthesis method was able to be extended to nanostructured Pt-Sn for ethanol oxidation in alkaline media. Nanostructured Pt-Sn electrocatalysts were evaluated in a unique approach tailored to electrocatalytic studies in alkaline media. At low temperatures, nanostructured Pt-Sn electrocatalysts were found to have significantly higher ethanol oxidation activity than a comparable nanostructured Pt catalyst. At higher temperatures, the oxygen-containing species contribution likely provided by Sn is insignificant due to a more oxidized Pt surface. The importance of the surface coverage of oxygen-containing species in the reaction mechanism is established in these studies. The investigations in this work present original studies of anion exchange ionomers as entrapment materials for rotating disc electrode (RDE) studies in alkaline media. Their significance is linked to the development of membrane electrode assemblies (MEAs) with the same ionomer for a KOH-free alkaline fuel cell (AFC).

  16. Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

    SciTech Connect (OSTI)

    Maio, A.; Fucarino, R.; Khatibi, R.; Botta, L.; Scaffaro, R.; Rosselli, S.; Bruno, M.

    2014-05-15

    Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H{sub 2}SO{sub 4}/H{sub 3}PO{sub 4} and KMnO{sub 4} based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors.

  17. Effects of low velocity air flow over alumina-silica insulating boards in solar environments

    SciTech Connect (OSTI)

    Maxwell, C.R.; Mulholland, G.P.; Couch, W.A.

    1987-01-01

    Results are reported from an experiment designed to determine whether low velocity air flow over insulating boards can increase their survivability in severe solar environments. The experiment was conducted at the Flux Gage Calibration Station located at Sandia National Laboratories' Solar Thermal Test Facility. Preliminary results indicate that the useful life for these boards can be significantly increased by air flowing over the hot surface of the board.

  18. Fracture Propagation and Permeability Change under Poro-thermoelastic Loads & Silica Reactivity in Enhanced Geothermal Systems

    SciTech Connect (OSTI)

    Ahmad Ghassemi

    2009-10-01

    Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Therefore, knowledge of the conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fractures are created in the reservoir using hydraulic fracturing. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result, it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have developed advanced poro-thermo-chemo-mechanical fracture models for rock fracture research in support of EGS design. The fracture propagation models are based on a regular displacement discontinuity formulation. The fracture propagation studies include modeling interaction of induced fractures. In addition to the fracture propagation studies, two-dimensional solution algorithms have been developed and used to estimate the impact of pro-thermo-chemical processes on fracture permeability and reservoir pressure. Fracture permeability variation is studied using a coupled thermo-chemical model with quartz reaction kinetics. The model is applied to study quartz precipitation/dissolution, as well as the variation in fracture aperture and pressure. Also, a three-dimensional model of injection/extraction has been developed to consider the impact poro- and thermoelastic stresses on fracture slip and injection pressure. These investigations shed light on the processes involved in the observed phenomenon of injection pressure variation (e.g., in Coso), and allow the assessment of the potential of thermal and chemical stimulation strategies.

  19. Synthesis of attrition-resistant heterogeneous catalysts using templated mesoporous silica

    DOE Patents [OSTI]

    Pham, Hien N.; Datye, Abhaya K.

    2003-04-15

    The present invention relates to catalysts in mesoporous structures. In a preferred embodiment, the invention comprises a method for encapsulating a dispersed insoluble compound in a mesoporous structure comprising combining a soluble oxide precursor, a solvent, and a surfactant to form a mixture; dispersing an insoluble compound in the mixture; spray-drying the mixture to produce dry powder; and calcining the powder to yield a porous structure comprising the dispersed insoluble compound.

  20. The Effect of Foaming and Silica Dissolution on Melter Feed Rheology...

    Office of Scientific and Technical Information (OSTI)

    As the nuclear waste glass melter feed is converted to molten glass, the feed eventually ... Resource Type: Conference Resource Relation: Conference: Waste Management 2014 (WM2014 ...

  1. Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

    DOE Patents [OSTI]

    Harris, Michael T.; Basaran, Osman A.; Sisson, Warren G.; Brunson, Ronald R.

    1997-01-01

    The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity.

  2. Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

    DOE Patents [OSTI]

    Harris, M.T.; Basaran, O.A.; Sisson, W.G.; Brunson, R.R.

    1997-02-18

    The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity. 3 figs.

  3. Silica and boron-containing ultraphosphate laser glass with low concentration quenching and improved thermal shock resistance

    DOE Patents [OSTI]

    Cook, Lee M.; Stokowski, Stanley E.

    1987-04-28

    Neodymium-doped phosphate glasses having a refractive index, nd>1.520; an Abbe number, Vd, <60; a density <3.0 g/cm.sup.3, a thermal expansion coefficient, .alpha., .ltoreq.110.times.10.sup.-7 .degree.C..sup.-1 ; a Young's Modulus, E, <70.times.10.sup.3 N/mm.sup.2 ; a Poisson's Ratio, .nu., <0.28; a thermal conductivity, K, >0.5 W/m.multidot.K, a thermal FOM=(1-.nu.).multidot.K/.alpha.E>0.7, consisting essentially of, in mol. %: P.sub.2 O.sub.5 : 40-70% SiO.sub.2 : 0-20% B.sub.2 O.sub.3 : 5-20% Sum SiO.sub.2 +B.sub.2 O.sub.3 : 5-35% Sum Li.sub.2 O+Na.sub.2 O+K.sub.2 O: 5-20% Sum La.sub.2 O.sub.3 +Nd.sub.2 O.sub.3 : 3-10% Sum MgO+CaO+SrO+BaO+ZnO: 0-10% and preferably containing an amount of Nd.sub.2 O.sub.3 effective for laser activity having an emission cross-section, .sigma., >3.5.times.10.sup.-20 cm.sup.2 ; a fluorescence linewidth (.DELTA..lambda..sub.f1)<23.5 nm; a first e-folding time of the Nd.sup.3+ fluorescence at 0.5 wt. % Nd.sub.2 O.sub.3 >375 .mu.sec, and a first e-folding time of the Nd.sup.3+ fluorescence at 10 wt. % >175 .mu.sec at 10 wt. %, have very low self-concentration quenching rates.

  4. Improved Mobility Control for Carbon Dioxide (CO{sub 2}) Enhanced Oil Recovery Using Silica-Polymer-Initiator (SPI) Gels

    SciTech Connect (OSTI)

    Oglesby, Kenneth

    2014-01-31

    SPI gels are multi-component silicate based gels for improving (areal and vertical) conformance in oilfield enhanced recovery operations, including water-floods and carbon dioxide (CO{sub 2}) floods, as well as other applications. SPI mixtures are like-water when pumped, but form light up to very thick, paste-like gels in contact with CO{sub 2}. When formed they are 3 to 10 times stronger than any gelled polyacrylamide gel now available, however, they are not as strong as cement or epoxy, allowing them to be washed / jetted out of the wellbore without drilling. This DOE funded project allowed 8 SPI field treatments to be performed in 6 wells (5 injection wells and 1 production well) in 2 different fields with different operators, in 2 different basins (Gulf Coast and Permian) and in 2 different rock types (sandstone and dolomite). Field A was in a central Mississippi sandstone that injected CO{sub 2} as an immiscible process. Field B was in the west Texas San Andres dolomite formation with a mature water-alternating-gas miscible CO{sub 2} flood. Field A treatments are now over 1 year old while Field B treatments have only 4 months data available under variable WAG conditions. Both fields had other operational events and well work occurring before/ during / after the treatments making definitive evaluation difficult. Laboratory static beaker and dynamic sand pack tests were performed with Ottawa sand and both fields’ core material, brines and crude oils to improve SPI chemistry, optimize SPI formulations, ensure SPI mix compatibility with field rocks and fluids, optimize SPI treatment field treatment volumes and methods, and ensure that strong gels set in the reservoir. Field quality control procedures were designed and utilized. Pre-treatment well (surface) injectivities ranged from 0.39 to 7.9 MMCF/psi. The SPI treatment volumes ranged from 20.7 cubic meters (m{sup 3}, 5460 gallons/ 130 bbls) to 691 m{sup 3} (182,658 gallons/ 4349 bbls). Various size and types of chemical/ water buffers before and after the SPI mix ensured that pre-gelled SPI mix got out into the formation before setting into a gel. SPI gels were found to be 3 to 10 times stronger than any commercially available cross-linked polyacrylamide gels based on Penetrometer and Bulk Gel Shear Testing. Because of SPI’s unique chemistry with CO{sub 2}, both laboratory and later field tests demonstrated that multiple, smaller volume SPI treatments maybe more effective than one single large SPI treatment. CO{sub 2} injectivities in injection well in both fields were reduced by 33 to 70% indicating that injected CO{sub 2} is now going into new zones. This reduction has lasted 1+ year in Field A. Oil production increased and CO{sub 2} production decreased in 5 Field A production wells, offsets to Well #1 injector, for a total of about 2,250 m{sup 3} (600,000 gallons/ 14,250 bbls) of incremental oil production- a $140 / SPI bbl return. Treated marginal production well, Field A Well #2, immediately began showing increased oil production totaling 238 m{sup 3} (63,000 gallons/ 1500 BBLs) over 1 year and an immediate 81% reduced gas-oil ratio.

  5. Mesoporous Silica-Supported Metal Oxide-Promoted Rh Nanocatalyst for Selective Production of Ethanol from Syngas

    SciTech Connect (OSTI)

    George Kraus

    2010-09-30

    The objective is to develop a process that will convert synthesis gas from coal into ethanol and then transform the ethanol into hydrogen. Principal investigators from Iowa State University include Dr. George Kraus, Dr. Victor Lin, Marek Pruski, and Dr. Robert Brown. Task 1 involves catalyst development and catalyst scale up. Mesoporous manganese silicate mixed oxide materials will be synthesized, characterized and evaluated. The first-and secondgeneration catalysts have been prepared and scaled up for use in Task 2. The construction of a high-pressure reactor system for producing synthetic liquid fuel from simulated synthesis gas stream has been completed as the first step in Task 2. Using the first- and second generation catalysts, the reactor has demonstrated the production of synthetic liquid fuel from a simulated synthesis gas stream.

  6. Coating thickness and coverage effects on the forces between...

    Office of Scientific and Technical Information (OSTI)

    forces between silica nanoparticles in water. Citation Details In-Document Search Title: Coating thickness and coverage effects on the forces between silica nanoparticles in water. ...

  7. Purification of water from cooling towers and other heat exchange systems

    DOE Patents [OSTI]

    Sullivan; Enid J. , Carlson; Bryan J. , Wingo; Robert M. , Robison; Thomas W.

    2012-08-07

    The amount of silica in cooling tower water is reduced by passing cooling tower water through a column of silica gel.

  8. Leach Capping | Open Energy Information

    Open Energy Info (EERE)

    silica Other definitions:Wikipedia Reegle Relict Geothermal Features Typical list of modern geothermal features Hydrothermally Deposited Rock Silica Deposition Carbonate...

  9. Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionaliz...

    Office of Scientific and Technical Information (OSTI)

    silica aerogels powders, with or without organic moiety and with or without sintering additive (colloidal silica), with three commercially available techniques: 1) hot uniaxial ...

  10. Advanced Feedstock Preprocessing

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... - Ability to selectively precipitate silica versus solubilized organics - Silica ... stover only meets cost targets in high production areas * Corn stover-based biorefineries ...

  11. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel ... The silver-functionalized silica aerogel proved to be an excellent candidate for this ...

  12. Process for direct conversion of reactive metals to glass (Patent...

    Office of Scientific and Technical Information (OSTI)

    is contacted with silica powder introduced in an air stream to form in one step a glass. ... contacted; silica; powder; introduced; air; stream; form; step; glass; cyclone; ...

  13. Dendrimer Templated Synthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole Hydrogenation.

    SciTech Connect (OSTI)

    Huang, Wenyu; Kuhn, John N.; Tsung, Chia-Kuang; Zhang, Yawen; Habas, Susan E.; Yang, Peidong; Somorjai, Gabor A.

    2008-05-09

    Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as {approx}1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H{sub 2} after reduction (76 torr of H{sub 2} mixed with 690 torr of He) at different temperatures. Catalysts were active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation.

  14. Atmospheric Pressure Chemical Vapor Deposition of High Silica SiO2-TiO2 Antireflective Thin Films for Glass Based Solar Panels

    SciTech Connect (OSTI)

    Klobukowski, Erik R; Tenhaeff, Wyatt E; McCamy, James; Harris, Caroline; Narula, Chaitanya Kumar

    2013-01-01

    The atmospheric pressure chemical vapor deposition (APCVD) of SiO2-TiO2 thin films employing [[(tBuO)3Si]2O-Ti(OiPr)2], which can be prepared from commercially available materials, results in antireflective thin films on float glass under industrially relevant manufacturing conditions. It was found that while the deposition temperature had an effect on the SiO2:TiO2 ratio, the thickness was dependent on the time of deposition. This study shows that it is possible to use APCVD employing a single source precursor containing titanium and silicon to produce thin films on float glass with high SiO2:TiO2 ratios.

  15. OSTI, US Dept of Energy, Office of Scientific and Technical Information |

    Office of Scientific and Technical Information (OSTI)

    Speeding access to science information from DOE and Beyond silica

  16. Fabrication of miniature fiber-optic temperature sensors

    DOE Patents [OSTI]

    Zhu, Yizheng; Wang, Anbo

    2010-07-27

    A method of coupling a silica fiber and a sapphire fiber includes providing a silica fiber having a doped core and a cladding layer, with the doped core having a prescribed diameter, providing a sapphire fiber having a diameter less than the doped core, placing an end of the sapphire fiber in close proximity to an end of the silica fiber, applying a heat source to the end of silica fiber and introducing the end of sapphire fiber into the heated doped core of the silica fiber to produce a coupling between the silica and sapphire fibers.

  17. Microsoft PowerPoint - Datskos_2015_UserProjectHighlight_AngewChemie

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    silica (silicon dioxide; SiO2) and hybrid microstructures made of silica and titania (titanium dioxide; TiO2). This approach provides a high degree of control of (1) shape, (2)...

  18. Aqueous biphasic plutonium oxide extraction process with pH and particle control

    DOE Patents [OSTI]

    Chaiko, David J.; Mensah-Biney, R.

    1997-01-01

    A method for simultaneously partitioning a metal oxide and silica from a material containing silica and the metal oxide, using a biphasic aqueous medium having immiscible salt and polymer phases.

  19. Aqueous biphasic plutonium oxide extraction process with pH and particle control

    DOE Patents [OSTI]

    Chaiko, D.J.; Mensah-Biney, R.

    1997-04-29

    A method is described for simultaneously partitioning a metal oxide and silica from a material containing silica and the metal oxide, using a biphasic aqueous medium having immiscible salt and polymer phases. 2 figs.

  20. Hot spot-derived shock initiation phenomena in heterogeneous...

    Office of Scientific and Technical Information (OSTI)

    Gas gun-driven plate impact experiments are used to produce well-defined shock inputs into nitromethane-silica mixtures containing size-selected silica beads at 6 wt%. The ...

  1. Characterization of Dry-Air Aged Granules of Silver-Functionalized...

    Office of Scientific and Technical Information (OSTI)

    Dry-Air Aged Granules of Silver-Functionalized Silica Aerogel Citation Details In-Document Search Title: Characterization of Dry-Air Aged Granules of Silver-Functionalized Silica ...

  2. THE EFFECT OF TEMPERATURE AND UNIAXIAL PRESSURE ON THE DENSIFICATION...

    Office of Scientific and Technical Information (OSTI)

    The silver-functionalized silica aerogel proved to be an excellent candidate for this ... for 2.5 min on densification of raw and silver-functionalized silica aerogel granules. ...

  3. Low-Cost, Haziness-Free, Transparent Insulation Based On a Porous...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Image of porous silica material in alcohol.
    Photo credit: Oak Ridge National Lab Image of porous silica material in alcohol. Photo credit: Oak Ridge National Lab Lead ...

  4. Co-electrospinning fabrication and photocatalytic performance...

    Office of Scientific and Technical Information (OSTI)

    Language: English Subject: 36 MATERIALS SCIENCE; HYDROXYL RADICALS; METHYLENE BLUE; NANOSTRUCTURES; PHOTOCATALYSIS; SILICA; SILICON OXIDES; SURFACE AREA; SURFACES; SYNTHESIS; ...

  5. Algae R&D Activities

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... with CHG Processing * Enable Nutrient Recycle Priority 2 Improve Extraction- Conversion ... Functionalized Mesoporous Silica Nanoparticles 9. LANL S121847 ...

  6. A thermodynamic and kinetic model for paste-aggregate interactions and

    Office of Scientific and Technical Information (OSTI)

    the alkali-silica reaction (Journal Article) | SciTech Connect Title: A thermodynamic and kinetic model for paste-aggregate interactions and the alkali-silica reaction A new conceptual model is developed for ASR formation based on geochemical principles tied to aqueous speciation, silica solubility, kinetically controlled mineral dissolution, and diffusion. ASR development is driven largely by pH and silica gradients that establish geochemical microenvironments between paste and aggregate,

  7. Effects of Surface Modification Conditions on Hydrophobicity of

    Office of Scientific and Technical Information (OSTI)

    Silica-based Coating Additives (Conference) | SciTech Connect Conference: Effects of Surface Modification Conditions on Hydrophobicity of Silica-based Coating Additives Citation Details In-Document Search Title: Effects of Surface Modification Conditions on Hydrophobicity of Silica-based Coating Additives Superhydrophobic silica (SHS) powders are being evaluated as a potential additive to the polyurethane topcoats used in Chemical Agent Resistant Coating (CARC) systems, with the goal of

  8. OSTI, US Dept of Energy, Office of Scientific and Technical Informatio...

    Office of Scientific and Technical Information (OSTI)

    polymers, biological polymers, semiconductor nanostructures, graphene, carbon, ... graphene, metals, OSTIBLOG, oxides, planet, polymers, semiconductor, silica Read more... ...

  9. Low cost routes to high purity silicon and derivatives thereof

    DOE Patents [OSTI]

    Laine, Richard M; Krug, David James; Marchal, Julien Claudius; Mccolm, Andrew Stewart

    2013-07-02

    The present invention is directed to a method for providing an agricultural waste product having amorphous silica, carbon, and impurities; extracting from the agricultural waste product an amount of the impurities; changing the ratio of carbon to silica; and reducing the silica to a high purity silicon (e.g., to photovoltaic silicon).

  10. Gelcasting Alumina Cores for Investment Casting

    SciTech Connect (OSTI)

    Janney, M A; Klug, F J

    2001-01-01

    General Electric currently uses silica investment casting cores for making superalloy turbine blades. The silica core technology does not provide the degree of dimensional control needed for advanced turbine system manufacture. The sum of the various process variables in silica core manufacturing produces cores that have more variability than is allowed for in advanced, power-generation gas turbine airfoils.

  11. LOW-LOSS CABLE AND METHOD OF FABRICATION

    DOE Patents [OSTI]

    McCarthy, R.L. et al.

    1960-09-27

    A radiation-resistant coaxial electrical cable capable of carrying very small currents at high voltages with little leakage is described. The cable comprises an inner axial conductor separated from an outer coaxial tubular conductor by annular layer of fibrous silica insulation. The silica insulation is formed by leaching boron from spun horosilicate glass and then heat treating the silica at a high temperature.

  12. Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized

    Office of Scientific and Technical Information (OSTI)

    Silica Aerogel (Technical Report) | SciTech Connect Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel Citation Details In-Document Search Title: Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents,

  13. Experimental and numerical study of the effective thermal conductivity of

    Office of Scientific and Technical Information (OSTI)

    silica nanocomposites with thermal boundary resistance (Journal Article) | SciTech Connect Experimental and numerical study of the effective thermal conductivity of silica nanocomposites with thermal boundary resistance Citation Details In-Document Search Title: Experimental and numerical study of the effective thermal conductivity of silica nanocomposites with thermal boundary resistance The thermal interface resistance at the macro scale is mainly described by the physical gap between two

  14. Reducing Logistics Footprints and Replenishment Demands: Nano-engineered

    Office of Scientific and Technical Information (OSTI)

    Silica Aerogels a Proven Method for Water Treatment (Technical Report) | SciTech Connect Technical Report: Reducing Logistics Footprints and Replenishment Demands: Nano-engineered Silica Aerogels a Proven Method for Water Treatment Citation Details In-Document Search Title: Reducing Logistics Footprints and Replenishment Demands: Nano-engineered Silica Aerogels a Proven Method for Water Treatment Rapid deployment and the use of objective force aggressively reduce logistic footprints and

  15. Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized

    Office of Scientific and Technical Information (OSTI)

    Silica Aerogel (Technical Report) | SciTech Connect Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel Citation Details In-Document Search Title: Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents,

  16. THE EFFECT OF TEMPERATURE AND UNIAXIAL PRESSURE ON THE DENSIFICATION

    Office of Scientific and Technical Information (OSTI)

    BEHAVIOR OF SILICA AEROGEL GRANULES (Conference) | SciTech Connect Conference: THE EFFECT OF TEMPERATURE AND UNIAXIAL PRESSURE ON THE DENSIFICATION BEHAVIOR OF SILICA AEROGEL GRANULES Citation Details In-Document Search Title: THE EFFECT OF TEMPERATURE AND UNIAXIAL PRESSURE ON THE DENSIFICATION BEHAVIOR OF SILICA AEROGEL GRANULES Materials are being developed in U.S. for the removal and immobilization of iodine from gaseous products of nuclear fuel reprocessing in support of the Fuel Cycle

  17. Assessment of the Current Level of Automation in the Manufacture of Fuel Cell Systems for Combined Heat and Power Applications

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Silica Aerogel (Technical Report) | SciTech Connect Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel Citation Details In-Document Search Title: Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents,

  18. Sichuan Chaolei Industry Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    Chaolei Industry Co Ltd Place: Chengdu, Sichuan Province, China Zip: 610041 Product: A Chinese company with plans to become partially-integrated PV products, ranging from silica...

  19. Desiccant Cooling Poised for Entry into Mainstream Markets

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Market projections include retrofits of existing buildings as well as new construction. Desiccant cooling systems use materials such as titanium silica gel to remove moisture from ...

  20. Search for: All records | DOE PAGES

    Office of Scientific and Technical Information (OSTI)

    ... with very similar energetic effects. less March 2016 , American Chemical Society Energy Landscape of Water and Ethanol on Silica Surfaces Wu, Di ; Guo, Xiaofeng ; Sun, Hui ...

  1. Reducing Logistics Footprints and Replenishment Demands: Nano...

    Office of Scientific and Technical Information (OSTI)

    Water Treatment Citation Details In-Document Search Title: Reducing Logistics Footprints and Replenishment Demands: Nano-engineered Silica Aerogels a Proven Method for Water ...

  2. "Title","Creator/Author","Publication Date","OSTI Identifier...

    Office of Scientific and Technical Information (OSTI)

    removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents, Ag0-functionalized silica aerogels, shows great...

  3. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    Silver Functionalized Silica Aerogel Matyas Josef Fryxell Glen E Robinson Matthew J Reprocessing Silver functionalized arogel Radioiodine Aging Sorption BET SEM XRD Reprocessing...

  4. Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionaliz...

    Office of Scientific and Technical Information (OSTI)

    removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents, Ag0-functionalized silica aerogels, shows great...

  5. Characterization of Dry-Air Aged Granules of Silver-Functionalized...

    Office of Scientific and Technical Information (OSTI)

    Silica Aerogel Matyas, Josef; Fryxell, Glen E.; Robinson, Matthew J. Reprocessing; Silver-functionalized arogel; Radioiodine; Aging; Sorption; BET; SEM; XRD...

  6. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant One of these new sorbents Ag0 functionalized silica aerogels shows great...

  7. Silicification | Open Energy Information

    Open Energy Info (EERE)

    surface Other definitions:Wikipedia Reegle Relict Geothermal Features Typical list of modern geothermal features Hydrothermally Deposited Rock Silica Deposition Carbonate...

  8. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Carbon nanomaterials in silica aerogel matrices Hamilton, Christopher E ; Chavez, Manuel E ; Duque, Juan G ; Gupta, Gautam ; Doorn, Stephen K ; Dattelbaum, Andrew M ; Obrey, ...

  9. Uranium and Strontium Batch Sorption and Diffusion Kinetics into...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Uranium and Strontium Batch Sorption and Diffusion Kinetics into Mesoporous Silica Friday, February 27, 2015 Figure 1 Figure 1. Transmission electron microscopy images of (A)...

  10. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    Treatment of Difficult Waters Arsenic Removal Silica Control Carbon Capture and Enhanced Oil Recovery Brady Patrick Vane Abstract not provided Sandia National Laboratories SNL NM...

  11. Microfluidic Polymer Valves - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Contact SNL About This Technology Check valve incorporating a mobile polymer
    monolith into a multiple-level silica microchannel. Check valve incorporating a mobile polymer ...

  12. Clean Firetube Boiler Waterside Heat Transfer Surfaces, Energy...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Scale deposits occur when calcium, magnesium, and silica, commonly found in most water ... The boilers steam production may be reduced if the fring rate cannot be increased to ...

  13. Nanoparticle Technology for Biorefinery of Non-Food Source Feedstocks

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Upper right: Transmission electron microscope image of mesoporous silica nanoparticles sample. Lower right: The pilot plant for nanoparticle-catalyzed production of biodiesel. ...

  14. Proposed "OneEERE" Work Plan Structure

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... during the power production process. Brookhaven National Laboratory investigated developing economic and environmentally acceptable methods for extracting silica from fluids in ...

  15. U.S. DOE Webinar Series - 2011-2012 Hydrogen Student Design Contest

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Total manure available per day is 27,387 kg. * 95% of rice production in California takes ... * Catalyst is Zeolite, Activated Carbon, Silica Gel * Cycling Schedule: Pressurization, ...

  16. ORNL/TM-2015/655

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Water with solid adsorption agent (e.g., silica gel or zeolite) Lech (2009) studied the ... However, the report stated that "like low- temperature geothermal power production, ...

  17. Catalytic Upgrading of Sugars to Hydrocarbons Technology Pathway

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... for the fermentative production of ethanol that target monomeric sugar utilization. ... in heat exchangers (e.g., silica) and contribute to catalyst poisoning (e.g., sulfur). ...

  18. Process Development for Nanostructured Photovoltaics

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Specifcally, researchers are applying silica aerogel to a conducting substrate. The ... Following further scale-up to a device suitable for mass production, additional commercial ...

  19. Confederated Tribes of Warm Springs - Geothermal Feasibility...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    * Volcanic rocks in the area are high in silica (dacite domes) and there is a high ... Estimate potential well flow rates and production potential based on conceptual models. * ...

  20. U.S. Mining Industry Energy Bandwidth Study

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... materials, including aluminum, beryllium, coal, copper, gold, iron, limestone, and silica. ... exploration and production industries, since similar equipment is used in both industries. ...

  1. Categorical Exclusion Determinations: Oklahoma | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... June 17, 2013 CX-010520: Categorical Exclusion Determination Silica Polymer Initiator ... PetrophysicsTight Rock Characterization for Improved Stimulation and Production ...

  2. Steam-Water Relative Permeability

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... for the REEs will be measured for both silica and MOF sorbents functionalized with a ... The sorbent providing the lowest overall production cost estimate for the REE extraction ...

  3. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    photoluminescence (1) scanning electron microscopy (1) silica (1) spectra (1) synthesis ... by field emission scanning electron microscopy interfaced with energy dispersive X-ray ...

  4. "Title","Creator/Author","Publication Date","OSTI Identifier...

    Office of Scientific and Technical Information (OSTI)

    Laboratory (LLNL), Livermore, CA","USDOE","59 BASIC BIOLOGICAL SCIENCES; 47 OTHER INSTRUMENTATION; DESIGN; DICHROISM; DILUTION; KINETICS; MIXERS; PROTEINS; SILICA; SPECTROSCOPY;...

  5. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    P Lengefeld J Horsley D Schuler B Bakajin O BASIC BIOLOGICAL SCIENCES OTHER INSTRUMENTATION DESIGN DICHROISM DILUTION KINETICS MIXERS PROTEINS SILICA SPECTROSCOPY...

  6. High temperature polymer concrete compositions

    DOE Patents [OSTI]

    Fontana, Jack J.; Reams, Walter

    1985-01-01

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system. A preferred formulation emphasizing the major necessary components is as follows: ______________________________________ Component A: Silica sand 60-77 wt. % Silica flour 5-10 wt. % Portland cement 15-25 wt. % Acrylamide 1-5 wt. % Component B: Styrene 50-60 wt. % Trimethylolpropane 35-40 wt. % trimethacrylate ______________________________________ and necessary initiators, accelerators, and surfactants.

  7. Remote Sensing For Geothermal Exploration Over Buffalo Valley...

    Open Energy Info (EERE)

    and spectral resolution of the data allows for the identification of carbonate, sulfate, silica and clay minerals. Quartz- and clay-rich regions of Buffalo Valley were...

  8. Surface Water Sampling At Chena Geothermal Area (Waring, Et Al...

    Open Energy Info (EERE)

    calcium and magnesium concentrations were measured, with elevated levels of silica and sulfate. Surface fumarole gases were tested with a flame to indicate carbon dioxide...

  9. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... This paper presents details of these experiments, and the extraction and analysis of the observed ... Franco ; et al We report on the design and commissioning of two silica ...

  10. Regenerable sorbent and method for removing hydrogen sulfide from hot gaseous mixtures

    DOE Patents [OSTI]

    Farrior, Jr., William L. (Morgantown, WV)

    1978-01-01

    Hydrogen sulfide is effectively removed from hot gaseous mixtures useful for industrial purposes by employing a solid absorbent consisting of silica-supported iron oxide in pellet form.

  11. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    SciTech Connect (OSTI)

    Liu, X. L.; Zhang, Z. M.

    2014-06-23

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  12. ABSTRACT

    Office of Scientific and Technical Information (OSTI)

    ... passed through Nafion tubing coiled inside a container containing silica gel desiccant. ... and the reductions in outdoor ozone production with cooler temperatures, the study was ...

  13. Interaction and Coalescence of Nanovoids and Dynamic Fracture...

    Office of Scientific and Technical Information (OSTI)

    of Nanovoids and Dynamic Fracture in Silica Glass: Multimiilion-to-Billion Atom Molecular Dynamics Simulations Citation Details In-Document Search Title: Interaction and...

  14. "Title","Creator/Author","Publication Date","OSTI Identifier...

    Office of Scientific and Technical Information (OSTI)

    order 1 nls, loading sample volumes on the order of microliters, and the ability to manufacture in fused silica for compatibility with most spectroscopic methods.",,"United...

  15. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    of order nl s loading sample volumes on the order of microliters and the ability to manufacture in fused silica for compatibility with most spectroscopic methods Lawrence...

  16. Microsecond Microfluidic Mixing for Investigation of Protein...

    Office of Scientific and Technical Information (OSTI)

    order 1 nls, loading sample volumes on the order of microliters, and the ability to manufacture in fused silica for compatibility with most spectroscopic methods. Lawrence...

  17. Geothermometry At U.S. Midwest Region (Vugrinovich, 1987) | Open...

    Open Energy Info (EERE)

    Activity Date Usefulness useful DOE-funding Unknown Notes Michigan "The silica heat flow estimator does provide estimates of surface heat flow which appear to be in good...

  18. ADVANCED COMPOSITE WIND TURBINE BLADE DESIGN BASED ON DURABILITY...

    Office of Scientific and Technical Information (OSTI)

    ... Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 17 ... SERVICE LIFE; SHEAR PROPERTIES; SILICA; TESTING; TOLERANCE; TURBINE BLADES; WIND TURBINES ...

  19. --No Title--

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    by benzyl alcohol than conventional ZSM-5 and amorphous silica-alumina. Also Pt and Pd supported on mesoporous ZSM- 5 gave much higher hydrodesulfurization activities than Pt...

  20. Geothermal research at the Puna Facility

    SciTech Connect (OSTI)

    Chen, B.

    1986-05-01

    Chemical analyses were conducted on the flocculated silica samples obtained during previous field experiments at HGP-A on both flashed and unflashed brines to determine the composition of the recovered silica for specific constituents of the brine which seem to often be entrapped in the silica during the flocculation process. Metals added as flocculants to the brine were also analyzed in order to evaluate the ease or difficulty with which these can be removed from the precipitated silica under varying conditions. Conditions employed included simple distilled water and acid washing (HCl of varying concentration).

  1. Geothermometry At Lualualei Valley Area (Thomas, 1986) | Open...

    Open Energy Info (EERE)

    have been commonly used in Hawaii for identifying geothermal potential (i.e. silica concentration and chloride to magnesium ion ratios) were anomalous in the groundwater of this...

  2. Nano compartments may aid drug delivery, catalyst design > Archived...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    researcher Teeraporn Suteewong and graduate student Hiroaki Sai, have tweaked familiar "sol-gel" chemistry used to self-assemble porous silica particles, making the assembly shift...

  3. Negotiable Licensing

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Current Diamond Film Field Emission Cathode Room Temperature Dispenser Photocathode Biotechnology (0) None currently. Chemistry (2) Insensitive Extrudable Explosive Silica Scaling...

  4. DECOMPOSITION OF CALCIUM SULFATE: A REVIEW OF THE LITERATURE

    Office of Scientific and Technical Information (OSTI)

    ... of silica or kaolin or one of three ,types of bauxite: Measurable decomposition (1%) ... Tennessee J. F. Flagg, Universal Oil Products Co. V. Forlenca, Englehard Industries R. L. ...

  5. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... States) Idaho Chemical Processing Plant, Idaho Falls, ID (United States) Idaho National Engineering Laboratory, ... mixers (2) proteins (2) reaction kinetics (2) silica (2) ...

  6. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    of oxygen in polymer membranes; developed molecular models of single-walled carbon nano-tube and nano-fumed silica PDMS membranes, and zeolites-modulated polyimide...

  7. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, I.O.

    1994-12-06

    A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft. 3 figures.

  8. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... of silica by means of chemical coagulation from source ... a power plant, providing process sketches, heat and material balances and equipment sizing for recovery schemes ...

  9. June 2015 Most Viewed Documents for Biology And Medicine | OSTI...

    Office of Scientific and Technical Information (OSTI)

    FRACTURED RESERVOIRS IN CARBONATE ROCKS: THE MICHIGAN BASIN James R. Wood; William B. Harrison (2002) 25 Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, ...

  10. March 2014 Most Viewed Documents for Biology And Medicine | OSTI...

    Office of Scientific and Technical Information (OSTI)

    FRACTURED RESERVOIRS IN CARBONATE ROCKS: THE MICHIGAN BASIN James R. Wood; William B. Harrison (2002) 11 > Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, ...

  11. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, Ival O.

    1994-01-01

    A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft.

  12. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, I.O.

    1995-12-26

    A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft. 3 figs.

  13. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, Ival O.

    1995-01-01

    A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft.

  14. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Filter Results Filter by Subject chem (6) materials science (3) silicon (3) irradiation (2) laser radiation (2) silica (2) texture (2) thin films (2) alignment (1) buffers (1) ...

  15. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    irradiation (12) high temperature (11) metals, ceramics, ... silica and its relatively low capture cross section enable ... EFFECT OF HEAT TREATMENT AND IRRADIATION BY NEUTRONS ON THE ...

  16. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... (1) flocculation (1) removal (1) scale control (1) silica (1) sodium compounds (1) ... simple, and compatible with other industrial processes. less Full Text Available ...

  17. Nesjavellir Geothermal Area | Open Energy Information

    Open Energy Info (EERE)

    World Geothermal Power Generation 2001-2005. Proceedings of World Geothermal Congress; Turkey: World Geothermal Congress. Reducing Silica Deposition Potential in Waste Waters...

  18. Artificial films mimic myelin sheath in new research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    phospholipids onto a silicon wafer substrate. Then the team used a near room temperature method to expose the highly ordered lipid films to vapors of silica precursor and...

  19. Windows Projects | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Lead Performer: Heliotrope Technologies - Oakland, CA Partner: Lawrence Berkeley National Laboratory - Berkeley, CA Image of porous silica material in alcohol.
    Photo credit: ...

  20. Optically transparent and environmentally durable superhydrophobic...

    Office of Scientific and Technical Information (OSTI)

    The functionalized silica nanoparticles were dissolved in a solution of the solvents isopropyl alcohol and 4-chlorobenzotrifluoride (PCBTF) and a proprietary ceramic binder ...

  1. Center for Nanophase Materials Sciences (CNMS) - CNMS Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    requires identifying structural intermediates and correlating their formation with genes and proteins involved. In T. pseudonana, distinct silica morphologies were observed...

  2. High temperature polymer concrete

    DOE Patents [OSTI]

    Fontana, J.J.; Reams, W.

    1984-05-29

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system.

  3. Aqueous biphasic extraction process with pH and particle control

    DOE Patents [OSTI]

    Chaiko, D.J.; Mensah-Biney, R.

    1995-05-02

    A process for aqueous biphasic extraction of metallic oxides and the like from substances containing silica. Control of media pH enables efficient and effective partition of mixture components. The inventive method may be employed to remove excess silica from kaolin clay. 2 figs.

  4. Aqueous biphasic extraction process with pH and particle control

    DOE Patents [OSTI]

    Chaiko, David J.; Mensah-Biney, R.

    1995-01-01

    A process for aqueous biphasic extraction of metallic oxides and the like from substances containing silica. Control of media pH enables efficient and effective partition of mixture components. The inventive method may be employed to remove excess silica from kaolin clay.

  5. SEPARATION OF RUTHENIUM COMPOUNDS FROM GASEOUS MIXTURES

    DOE Patents [OSTI]

    Newby, B.J.; Hanson, D.A.; May, C.E.

    1960-12-13

    A process is given for removing RuO/sub 4/ from waste calcination off- gases by adsorption on silica gel, preferably of from 70 to 80 deg C. The RuO/sub 4/ can be eluted from the silica gel with water of a temperature between 60 and 70 deg C.

  6. Geothermal research at the Puna Facility. Technical report

    SciTech Connect (OSTI)

    Chen, B.

    1986-04-01

    This report consists of a summary of the experiments performed to date at the Puna Geothermal Research Facility on silica in the geothermal fluid from the HGP-A well. Also presented are some results of investigations in commercial applications of the precipitated silica. (ACR)

  7. One-step synthesis of mesoporous pentasil zeolite with single-unit-cell lamellar structural features

    DOE Patents [OSTI]

    Tsapstsis, Michael; Zhang, Xueyi

    2015-11-17

    A method for making a pentasil zeolite material includes forming an aqueous solution that includes a structure directing agent and a silica precursor; and heating the solution at a sufficient temperature and for sufficient time to form a pentasil zeolite material from the silica precursor, wherein the structure directing agent includes a quaternary phosphonium ion.

  8. Theory of the electronic and structural properties of solid state oxides

    SciTech Connect (OSTI)

    Chelikowsky, J.R.

    1990-01-01

    Studies on electronic and structural properties of solid state oxides continued. This quarter, studies have concentrated on silica. Progress is discussed in the following sections: interatomic potentials and the structural properties of silica; chemical reactivity and covalent/metallic bonding on Si clusters; and surface and thermodynamic interatomic forces fields for silicon. 64 refs., 20 figs., 5 tabs. (CBS)

  9. Composite multilayer insulations for thermal protection of aerospace vehicles

    SciTech Connect (OSTI)

    Kourtides, D.A.; Pitts, W.C.

    1989-02-01

    Composite flexible multilayer insulation systems (MLI), consisting of alternating layers of metal foil and scrim cloth or insulation quilted together using ceramic thread, were evaluated for thermal performance and compared with a silica fibrous (baseline) insulation system. The systems studied included: (1) alternating layers of aluminoborosilicate (ABS) scrim cloth and stainless steel foil, with silica, ABS, or alumina insulation; (2) alternating layers of scrim cloth and aluminum foil, with silica or ABS insulation; (3) alternating layers of alumininum foil and silica or ABS insulation; and (4) alternating layers of aluminum-coated polyimide placed on the bottom of the silica insulation. The MLIs containing aluminum were the most efficient, measuring as little as half the backface temperature increase of the baseline system.

  10. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, I.O.

    1993-10-19

    Free flowing, conformable powder-like mix of silica particles and a phase change material (pcm) is disclosed. The silica particles have a critical size of about 7[times]10[sup [minus]3] to about 7[times]10[sup [minus]2] microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 10 figures.

  11. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, I.O.

    1993-05-18

    Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7[times]10[sup [minus]3] to about 7[times]10[sup [minus]2] microns and the p.c.m. must be added to the silica in an amount of 80 wt. % or less p.c.m. per combined weight of silica and p.c.m. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a p.c.m. material. The silica-p.c.m. mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

  12. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, Ival O.

    1993-01-01

    Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7.times.10.sup.-3 to about 7.times.10.sup.-2 microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garmets, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

  13. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, I.O.

    1992-04-21

    A free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7 [times] 10[sup [minus]3] to about 7 [times] 10[sup [minus]2] microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 9 figs.

  14. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, Ival O.

    1993-01-01

    Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7.times.10.sup.-3 to about 7.times.10.sup.-2 microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

  15. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, I.O.

    1994-02-01

    Free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a PCM material. The silica-PCM mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 2 figures.

  16. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, Ival O.

    1994-01-01

    Free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a PCM material. The silica-PCM mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

  17. Dry powder mixes comprising phase change materials

    DOE Patents [OSTI]

    Salyer, Ival O.

    1992-01-01

    Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7.times.10.sup.-3 to about 7.times.10.sup.-2 microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

  18. Method of handling radioactive alkali metal waste

    DOE Patents [OSTI]

    Wolson, Raymond D.; McPheeters, Charles C.

    1980-01-01

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  19. Method of handling radioactive alkali metal waste

    DOE Patents [OSTI]

    Wolson, R.D.; McPheeters, C.C.

    Radioactive alkali metal is mixed with particulate silica in a rotary drum reactor in which the alkali metal is converted to the monoxide during rotation of the reactor to produce particulate silica coated with the alkali metal monoxide suitable as a feed material to make a glass for storing radioactive material. Silica particles, the majority of which pass through a 95 mesh screen or preferably through a 200 mesh screen, are employed in this process, and the preferred weight ratio of silica to alkali metal is 7 to 1 in order to produce a feed material for the final glass product having a silica to alkali metal monoxide ratio of about 5 to 1.

  20. Innovative Concepts Phase I: Inorganic Membranes for CO2/N2 Separation

    SciTech Connect (OSTI)

    William Desisto

    2003-09-23

    Silica membranes were prepared using a novel technique of catalyzed-atomic layer deposition of silica within a mesoporous matrix. Pyridine was used to catalyze the silicon chloride attachment to the hydroxylated silica surface at room temperature. This half-reaction was followed by the hydration of the surface with water regenerating surface hydroxyls and completing one reaction cycle. The technique resulted in the self-limited pore size reduction of the mesoporous matrix to pore sizes near 1 nm. The self-limited reaction was presumed to be the exclusion of the large catalyst molecule from the pore entrance. In addition to pore size reduction, viscous flow defects were repaired without significantly reducing overall porosity of the membrane. In addition, we investigated the ability of amine-functionalization to enhance the CO{sub 2} transport in silica membranes. Specifically, we examined three synthesis techniques for functionalizing silica membranes with amino groups that resulted in different surface chemistries of the silica membranes. These differences were correlated with changes in the CO{sub 2} facilitation characteristics. It was found that high loadings of amino groups where interaction with the silica surface was minimized promoted the highest CO{sub 2} transport.