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1

Silica Geothermometers | Open Energy Information  

Open Energy Info (EERE)

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2

A new illite geothermometer  

SciTech Connect (OSTI)

Sericite, either as illite or illite/smectite, is ubiquitous in geothermal systems. Theoretical Ca- and Na-smectite contents of non-expanding geothermal sericites have been calculated from published electron microprobe analyses. Geothermal sericites can be modeled as solid solutions of muscovite and smectite. For those sericites that fit the model, the amount of smectite in solid solution is related to temperature by the expression TºC = 1000/(0.45LogX{sub smectite} + 2.38) – 273. The temperature dependence of illite interlayer chemistry suggests a related temperature dependence of the K, Na and Ca content of geothermal fluids. The original data used by Fournier and Truesdell (1973) to derive the empirical Na-K-Ca geothermometer for geothermal fluids can be modeled equally well by an equation incorporating the equilibrium constant for the reaction of smectite to illite: T ºC = 1.145*10{sup 3}/([0.35LogNa + 0.175LogCa – 0.75LogK] + 1.51) – 273, where the concentration units are molalities. This supports the hypothesis that illite and illite/smectite are important controls on the concentrations of Na, K and Ca in geothermal fluids.

Ballantyne, Judith M.; Moore, Joseph N.

1988-01-01T23:59:59.000Z

3

Multicomponent Geothermometers | Open Energy Information  

Open Energy Info (EERE)

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4

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:...

5

Category:Silica Geothermometers | Open Energy Information  

Open Energy Info (EERE)

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6

Cation Geothermometers | Open Energy Information  

Open Energy Info (EERE)

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7

Evaluation Of Chemical Geothermometers For Calculating Reservoir  

Open Energy Info (EERE)

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8

Cation Geothermometers At Lightning Dock Geothermal Area (Witcher, 2006) |  

Open Energy Info (EERE)

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9

Chemical Geothermometers And Mixing Models For Geothermal Systems | Open  

Open Energy Info (EERE)

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10

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

Open Energy Info (EERE)

errors (2-3%) than for the original equation (5-29%). Authors Surendra P. Verma and Edgar Santoyo Published Journal Journal of Volcanology and Geothermal Research, 1997 DOI Not...

11

Application Of An Artificial Neural Network Model To A Na-K Geothermometer  

Open Energy Info (EERE)

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12

New Improved Equations For Na-K, Na-Li And Sio2 Geothermometers By Outlier  

Open Energy Info (EERE)

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13

A New Improved Na-K Geothermometer By Artificial Neural Networks | Open  

Open Energy Info (EERE)

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14

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

Open Energy Info (EERE)

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15

Geothermal reservoir temperatures estimated from the oxygen isotope...  

Open Energy Info (EERE)

drillholes have been tested as a geothermometer in three areas of the western United States. Limited analyses of spring and borehole fluids and existing experimental rate...

16

Geothermal Reservoir Temperatures Estimated from the Oxygen Isotope...  

Open Energy Info (EERE)

drillholes have been tested as a geothermometer in three areas of the western United States. Limited analyses of spring and borehole fluids and existing experimental rate...

17

Improvements in geothermometry. Final technical report  

SciTech Connect (OSTI)

The following are covered: the basis of the Na-K-Ca geothermometer, geothermometry via model calculations, non ideality and complexing, and experimental calibration.

Potter, J.; Dibble, W.; Parks, G.; Nur, A.

1982-07-01T23:59:59.000Z

18

An experimental investigation into the effects of fluid composition on certain geothermometry methods  

E-Print Network [OSTI]

at the lower temperatures, and 5) thermal waters do not mix with shallower, cooler ground water. Silica geothermometer The dissolved silica content of geothermal water is used in geothermometry because silica is present in most geologic settings... that the time required to attain equilibrium was 100 hours at 200 C and from four to sixteen hours at 0 360 C. Work at lower temperatures (25 C, 60 -100 C) was done by van Lier, de Bruyn, and Overbeek (1960) using finely ground quartz particles...

Pope, Leslie Anne

1985-01-01T23:59:59.000Z

19

Kinetics of Silica Polymerization  

E-Print Network [OSTI]

geothermal brines:’ Avoidance or minimization of silica supersaturation Supersaturation can be avoided by preventing cooling

Weres, Oleh

2011-01-01T23:59:59.000Z

20

Silica extraction from geothermal water  

DOE Patents [OSTI]

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.

Bourcier, William L; Bruton, Carol J

2014-09-23T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Silica in Protoplanetary Disks  

E-Print Network [OSTI]

Mid-infrared spectra of a few T Tauri stars (TTS) taken with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope show prominent narrow emission features indicating silica (crystalline silicon dioxide). Silica is not a major constituent of the interstellar medium; therefore, any silica present in the circumstellar protoplanetary disks of TTS must be largely the result of processing of primitive dust material in the disks surrouding these stars. We model the silica emission features in our spectra using the opacities of various polymorphs of silica and their amorphous versions computed from earth-based laboratory measurements. This modeling indicates that the two polymorphs of silica, tridymite and cristobalite, which form at successively higher temperatures and low pressures, are the dominant forms of silica in the TTS of our sample. These high temperature, low pressure polymorphs of silica present in protoplanetary disks are consistent with a grain composed mostly of tridymite named Ada found in the cometary dust samples collected from the STARDUST mission to Comet 81P/Wild 2. The silica in these protoplanetary disks may arise from incongruent melting of enstatite or from incongruent melting of amorphous pyroxene, the latter being analogous to the former. The high temperatures of 1200K-1300K and rapid cooling required to crystallize tridymite or cristobalite set constraints on the mechanisms that could have formed the silica in these protoplanetary disks, suggestive of processing of these grains during the transient heating events hypothesized to create chondrules.

B. A. Sargent; W. J. Forrest; C. Tayrien; M. K. McClure; A. Li; A. R. Basu; P. Manoj; D. M. Watson; C. J. Bohac; E. Furlan; K. H. Kim; J. D. Green; G. C. Sloan

2008-11-21T23:59:59.000Z

22

Silica Scaling Removal Process  

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

systems Water treatment systems Water evaporation systems Potential mining applications (produced water) Industry applications for which silica scaling must be prevented Benefits:...

23

Kinetics of silica polymerization  

SciTech Connect (OSTI)

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.

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

1980-05-01T23:59:59.000Z

24

Silica Scaling Removal Process  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systemsBi (2)Sharing Smart GridShift EndSidneyChemistry » Silica Scaling

25

Removal of dissolved and colloidal silica  

DOE Patents [OSTI]

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.

Midkiff, William S. (Ruidoso, NM)

2002-01-01T23:59:59.000Z

26

Stabilized fuel with silica support structure  

SciTech Connect (OSTI)

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.

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

1991-12-31T23:59:59.000Z

27

Multicomponent Equilibrium Models for Testing Geothermometry Approaches  

SciTech Connect (OSTI)

Geothermometry is an important tool for estimating deep reservoir temperature from the geochemical composition of shallower and cooler waters. The underlying assumption of geothermometry is that the waters collected from shallow wells and seeps maintain a chemical signature that reflects equilibrium in the deeper reservoir. Many of the geothermometers used in practice are based on correlation between water temperatures and composition or using thermodynamic calculations based a subset (typically silica, cations or cation ratios) of the dissolved constituents. An alternative approach is to use complete water compositions and equilibrium geochemical modeling to calculate the degree of disequilibrium (saturation index) for large number of potential reservoir minerals as a function of temperature. We have constructed several “forward” geochemical models using The Geochemist’s Workbench to simulate the change in chemical composition of reservoir fluids as they migrate toward the surface. These models explicitly account for the formation (mass and composition) of a steam phase and equilibrium partitioning of volatile components (e.g., CO2, H2S, and H2) into the steam as a result of pressure decreases associated with upward fluid migration from depth. We use the synthetic data generated from these simulations to determine the advantages and limitations of various geothermometry and optimization approaches for estimating the likely conditions (e.g., temperature, pCO2) to which the water was exposed in the deep subsurface. We demonstrate the magnitude of errors that can result from boiling, loss of volatiles, and analytical error from sampling and instrumental analysis. The estimated reservoir temperatures for these scenarios are also compared to conventional geothermometers. These results can help improve estimation of geothermal resource temperature during exploration and early development.

Cooper, D. Craig; Carl D. Palmer; Robert W. Smith; Travis L. McLing

2013-02-01T23:59:59.000Z

28

Cellular membrane trafficking of mesoporous silica nanoparticles  

SciTech Connect (OSTI)

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.

Fang, I-Ju

2012-06-21T23:59:59.000Z

29

Silica Supported Ceria Nanoparticles: A Hybrid Nanostructure...  

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

The surface chemical and vibrational spectroscopy analysis revealed cerium–silicate (Ce-O-Si) covalent bond linkage between silica and cerium oxide nanoparticles. The...

30

1 AQUEOUS SILICA POLYMERIZATION IN Silica polymers have long been recognized in aque-  

E-Print Network [OSTI]

1 AQUEOUS SILICA POLYMERIZATION IN PURE H2O Silica polymers have long been recognized in aque- ous is accompanied by increased extent of polymerization. Silica concentrations in equilibrium with quartz. In the system SiO2-H2O, the structure of supercritical hy- drous SiO2 melt is strongly polymerized at

Manning, Craig

31

Characterizing Surface Acidic Sites in Mesoporous-Silica-Supported...  

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

Surface Acidic Sites in Mesoporous-Silica-Supported Tungsten Oxide Catalysts Using Solid State NMR and Quantum Characterizing Surface Acidic Sites in Mesoporous-Silica-Supported...

32

Synthesis of supported carbon nanotubes in mineralized silica...  

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

supported carbon nanotubes in mineralized silica-wood composites. Synthesis of supported carbon nanotubes in mineralized silica-wood composites. Abstract: Multiwall carbon...

33

Synthesis and properties of Chitosan-silica hybrid aerogels  

E-Print Network [OSTI]

chitosan-silica composite aerogels can be easily synthesizedphysical properties of these aerogels. These materials may1. Top: Chitosan-silica aerogel (sample 4), Bottom: Same

Ayers, Michael R.; Hunt, Arlon J.

2001-01-01T23:59:59.000Z

34

Sample Desorption/Onization From Mesoporous Silica  

DOE Patents [OSTI]

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.

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

2005-10-25T23:59:59.000Z

35

PROCEEDINGS, Twenty-Seventh Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 28-30, 2002  

E-Print Network [OSTI]

probably by the drilling fluid. When applied on all these fluids, numerous chemical geothermometers yield. On the three bore-holes drilled by CFG in this area, only the bore-hole located more at north (Californie bore-hole) and near the old LA-101 bore- hole, indicated the presence of inflows of hot fluid close to 90°C starting

Boyer, Edmond

36

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...

37

Compound and Elemental Analysis At Lassen Volcanic National Park...  

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...

38

Proceedings World Geothermal Congress 2005 Antalya, Turkey, 24-29 April 2005  

E-Print Network [OSTI]

Proceedings World Geothermal Congress 2005 Antalya, Turkey, 24-29 April 2005 1 Geothermal: Martinique, geothermal exploration, thermal springs, soil gas profiles, chemical geothermometers ABSTRACT in starting again geothermal research on the Martinique island, in the Lesser Antilles. The first works, which

Paris-Sud XI, Université de

39

The solubility of natural quartz sand at 100?C, and 150?C, 345 bars: an experimental investigation in a flow-through hydrothermal system  

E-Print Network [OSTI]

geothermometers and mixing for geothermal systems. Geothermi cs 5, 41-50. Foumier R. O. and Potter R. W. II (1982) An equation correlating the solubility of quartz in water from 25' to 900' C at pressures up to 10, 000 bars, Geochim. Cosrnochim. Acta 46, 1969...

Burns, Gregory Lee

2012-06-07T23:59:59.000Z

40

Hollow silica and silica-boron nano/microparticles for contrast-enhanced ultrasound to detect small tumors  

E-Print Network [OSTI]

Hollow silica and silica-boron nano/microparticles for contrast-enhanced ultrasound to detect small Accepted 18 March 2012 Available online 11 April 2012 Keywords: Ultrasound Nano Silica Shells Imaging detection, gas filled hollow boron-doped silica particles have been developed, which can be used

Kummel, Andrew C.

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

LIGHT SCATTERING STUDIES OF SILICA AEROGELS  

E-Print Network [OSTI]

S.S. , "Coherent Expanded Aerogels," J. of Phys. Chern.Production of Silica Aerogel," Physica Scripta 23, Nicolaon,S.J. , "Preparation des aerogels de silice a partir

Hunt, A.J.

2010-01-01T23:59:59.000Z

42

Properties and Structures of Sulfonated Syndiotactic Polystyrene Aerogel and Syndiotactic Polystyrene/Silica Hybrid Aerogel.  

E-Print Network [OSTI]

??This study focuses on hybrid aerogels of syndiotactic polystyrene (sPS) and silica where silica concentration is varied and silica condensation conditions are varied to produce… (more)

Zhang, Huan

2014-01-01T23:59:59.000Z

43

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

SciTech Connect (OSTI)

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.

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

1999-07-01T23:59:59.000Z

44

E-Print Network 3.0 - alumina silica-alumina etude Sample Search...  

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

14 (2004) 681686 PII: S0960-1317(04)71691-5 Summary: for silica, alumina, and titania aerogels. Silica and alumina aerogel cantilevers are fabricated on the basis... Silica Silica...

45

High resolution patterning of silica aerogels  

SciTech Connect (OSTI)

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.

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

2008-10-30T23:59:59.000Z

46

Measurement of muonium emission from silica aerogel  

E-Print Network [OSTI]

Emission of muonium ($\\mu^{+}e^{-}$) atoms from silica aerogel into vacuum was observed. Characteristics of muonium emission were established from silica aerogel samples with densities in the range from 29 mg cm$^{-3}$ to 178 mg cm$^{-3}$. Spectra of muonium decay times correlated with distances from the aerogel surfaces, which are sensitive to the speed distributions, follow general features expected from a diffusion process, while small deviations from a simple room-temperature thermal diffusion model are identified. The parameters of the diffusion process are deduced from the observed yields.

P. Bakule; G. A. Beer; D. Contreras; M. Esashi; Y. Fujiwara; Y. Fukao; S. Hirota; H. Iinuma; K. Ishida; M. Iwasaki; T. Kakurai; S. Kanda; H. Kawai; N. Kawamura; G. M. Marshall; H. Masuda; Y. Matsuda; T. Mibe; Y. Miyake; S. Okada; K. Olchanski; A. Olin; H. Onishi; N. Saito; K. Shimomura; P. Strasser; M. Tabata; D. Tomono; K. Ueno; K. Yokoyama; S. Yoshida

2013-06-17T23:59:59.000Z

47

Measurement of muonium emission from silica aerogel  

E-Print Network [OSTI]

Emission of muonium ($\\mu^{+}e^{-}$) atoms from silica aerogel into vacuum was observed. Characteristics of muonium emission were established from silica aerogel samples with densities in the range from 29 mg cm$^{-3}$ to 178 mg cm$^{-3}$. Spectra of muonium decay times correlated with distances from the aerogel surfaces, which are sensitive to the speed distributions, follow general features expected from a diffusion process, while small deviations from a simple room-temperature thermal diffusion model are identified. The parameters of the diffusion process are deduced from the observed yields.

Bakule, P; Contreras, D; Esashi, M; Fujiwara, Y; Fukao, Y; Hirota, S; Iinuma, H; Ishida, K; Iwasaki, M; Kakurai, T; Kanda, S; Kawai, H; Kawamura, N; Marshall, G M; Masuda, H; Matsuda, Y; Mibe, T; Miyake, Y; Okada, S; Olchanski, K; Olin, A; Onishi, H; Saito, N; Shimomura, K; Strasser, P; Tabata, M; Tomono, D; Ueno, K; Yokoyama, K; Yoshida, S

2013-01-01T23:59:59.000Z

48

A threshold Cherenkov detector for K separation using silica aerogel  

E-Print Network [OSTI]

A threshold Cherenkov detector for Kþ =pþ separation using silica aerogel R. Siudak a,b , A August 2008 Keywords: Threshold Cherenkov detector Silica aerogel Reaction pp ! Kþ ðLp� Kþ =pþ separation in the focal plane of a magnetic spectrograph. Silica aerogel with refractive index of n ¼ 1:05 is applied

Magiera, Andrzej

49

Catalysis over activated high silica zeolites  

SciTech Connect (OSTI)

A process is provided for conducting organic compound conversion over a catalyst composition comprising a crystalline zeolite having a high initial silica-to-alumina mole ratio, said zeolite being prepared by calcining the zeolite, contacting said calcined zeolite with solid aluminum fluoride, and coverting said aluminum fluoride contacted material to hydrogen form.

Chang, C. D.; Miale, N.

1985-07-23T23:59:59.000Z

50

Chemistry of Silica in Cerro Prieto Brines  

E-Print Network [OSTI]

1975). When operated without sludge r e c i r c u l a t i ot o c o l l o i d a l silica. sludge accumulation there. thel a t i o n of part of the sludge coming out of The l a r g

Weres, Oleh

2012-01-01T23:59:59.000Z

51

Chemistry of Silica in Cerro Prieto Brines  

E-Print Network [OSTI]

1975). When operated without sludge r e c i r c u l a t i ot o c o l l o i d a l silica. sludge accumulation there. thel a t i o n of part of the sludge coming out of The l a r g

Weres, O.

2010-01-01T23:59:59.000Z

52

Molecular sieving silica membrane fabrication process  

DOE Patents [OSTI]

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.

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

1999-01-01T23:59:59.000Z

53

Conversion of geothermal waste to commercial products including silica  

DOE Patents [OSTI]

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.

Premuzic, Eugene T. (East Moriches, NY); Lin, Mow S. (Rocky Point, NY)

2003-01-01T23:59:59.000Z

54

Carbon nanomaterials in silica aerogel matrices  

SciTech Connect (OSTI)

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.

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

2010-01-01T23:59:59.000Z

55

Light-scattering studies of silica aerogels  

SciTech Connect (OSTI)

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.

Hunt, A.J.

1983-02-01T23:59:59.000Z

56

Recent progress in silica aerogel Cherenkov radiator  

E-Print Network [OSTI]

In this paper, we present recent progress in the development of hydrophobic silica aerogel as a Cherenkov radiator. In addition to the conventional method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile handling for crack-free aerogels were investigated. Sufficient photons were detected from high-performance aerogels in a beam test.

Makoto Tabata; Ichiro Adachi; Hideyuki Kawai; Masato Kubo; Takeshi Sato

2012-03-19T23:59:59.000Z

57

Recent progress in silica aerogel Cherenkov radiator  

E-Print Network [OSTI]

In this paper, we present recent progress in the development of hydrophobic silica aerogel as a Cherenkov radiator. In addition to the conventional method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile handling for crack-free aerogels were investigated. Sufficient photons were detected from high-performance aerogels in a beam test.

Tabata, Makoto; Kawai, Hideyuki; Kubo, Masato; Sato, Takeshi

2012-01-01T23:59:59.000Z

58

Novel silica-based ion exchange resin  

SciTech Connect (OSTI)

Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

NONE

1997-11-01T23:59:59.000Z

59

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents [OSTI]

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.

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

1996-01-02T23:59:59.000Z

60

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents [OSTI]

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.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1996-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents [OSTI]

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.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1994-01-01T23:59:59.000Z

62

Silica powders for powder evacuated thermal insulating panel and method  

DOE Patents [OSTI]

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.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1995-01-01T23:59:59.000Z

63

Characterisation of Dust Particles Trapped in Silica Aerogels.  

E-Print Network [OSTI]

?? This thesis involves the study of dust particles trapped in silica aerogel for fusion dust diagnostics purpose. The low velocity impact experiments are done… (more)

Liu, Bing

2011-01-01T23:59:59.000Z

64

Feasibility of using silica aerogel as insulation for buildings.  

E-Print Network [OSTI]

?? For recent years, silica aerogel has attracted great attention and been extensively used in different technical fields owning to its remarkable properties in optics,… (more)

Huang, Lang

2012-01-01T23:59:59.000Z

65

Fibrous composites comprising carbon nanotubes and silica  

DOE Patents [OSTI]

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.

Peng, Huisheng (Shanghai, CN); Zhu, Yuntian Theodore (Cary, NC); Peterson, Dean E. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM)

2011-10-11T23:59:59.000Z

66

Hydrophobic silica aerogel production at KEK  

E-Print Network [OSTI]

We present herein a characterization of a standard method used at the High Energy Accelerator Research Organization (KEK) to produce hydrophobic silica aerogels and expand this method to obtain a wide range of refractive index (n = 1.006-1.14). We describe in detail the entire production process and explain the methods used to measure the characteristic parameters of aerogels, namely the refractive index, transmittance, and density. We use a small-angle X-ray scattering (SAXS) technique to relate the transparency to the fine structure of aerogels.

Tabata, Makoto; Kawai, Hideyuki; Sumiyoshi, Takayuki; Yokogawa, Hiroshi

2011-01-01T23:59:59.000Z

67

Hydrophobic silica aerogel production at KEK  

E-Print Network [OSTI]

We present herein a characterization of a standard method used at the High Energy Accelerator Research Organization (KEK) to produce hydrophobic silica aerogels and expand this method to obtain a wide range of refractive index (n = 1.006-1.14). We describe in detail the entire production process and explain the methods used to measure the characteristic parameters of aerogels, namely the refractive index, transmittance, and density. We use a small-angle X-ray scattering (SAXS) technique to relate the transparency to the fine structure of aerogels.

Makoto Tabata; Ichiro Adachi; Hideyuki Kawai; Takayuki Sumiyoshi; Hiroshi Yokogawa

2011-12-14T23:59:59.000Z

68

Electroactive Silica Nanoparticles for Biological Labeling. | EMSL  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed NewcatalystNeutronEnvironmentZIRKLEEFFECTSHighElectroactive Silica Nanoparticles for

69

Exploration of the Upper Hot Creek Ranch Geothermal Resource, Nye County, Nevada  

SciTech Connect (OSTI)

The Upper Hot Creek Ranch (UHCR) geothermal system had seen no significant exploration activity prior to initiation of this GRED III project. Geochemical geothermometers calculated from previously available but questionable quality analyses of the UHCR hot spring waters indicated possible subsurface temperatures of +320 oF. A complex Quaternary and Holocene faulting pattern associated with a six mile step over of the Hot Creek Range near the UHCR also indicated that this area was worthy of some exploration activity. Permitting activities began in Dec. 2004 for the temperature-gradient holes but took much longer than expected with all drilling permits finally being received in early August 2005. The drilling and geochemical sampling occurred in August 2005. Ten temperature gradient holes up to 500’ deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400’ encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The fifth hole, located within a narrow part of Hot Creek Canyon, encountered a maximum temperature of 81 oF at a depth of 105’ but had cooler temperatures at greater depth. Temperature data from this hole can not be extrapolated to greater depths. Any thermal anomaly associated with the UHCR geothermal system is apparently confined to the immediate vicinity of Hot Creek Canyon where challenges such as topography, a wilderness study area, and wetlands issues will make further exploration time consuming and costly. Ten water samples were collected for chemical analysis and interpretation. Analyses of three samples of the UHCR thermal give predicted subsurface temperatures ranging from 317 to 334 oF from the Na-K-Ca, silica (quartz), and Na-Li geothermometers. The fact that all three thermometers closely agree gives the predictions added credibility. Unfortunately, the final result of this exploration is that a moderate temperature geothermal resource has been clearly identified but it appears to be restricted to a relatively small area that would be difficult to develop.

Dick Benoit; David Blackwell

2006-01-01T23:59:59.000Z

70

Dye-Doped Silica Nanoparticle Labels/Protein Microarray for Detection...  

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

Dye-Doped Silica Nanoparticle LabelsProtein Microarray for Detection of Protein Biomarkers. Dye-Doped Silica Nanoparticle LabelsProtein Microarray for Detection of Protein...

71

Tailoring Structure Property Relationships and Elastic Phenomenon in Native and Polymer Reinforced Silica Aerogels.  

E-Print Network [OSTI]

?? The focus of this work was to study the effects of flexible silica backbones on elastic properties of silica aerogels. Two routes were examined.… (more)

Randall, Jason P.

2010-01-01T23:59:59.000Z

72

Community Geothermal Technology Program: Silica bronze project. Final report  

SciTech Connect (OSTI)

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.

Bianchini, H.

1989-10-01T23:59:59.000Z

73

ALUMINOSILICATE-COATED SILICA SAND FOR REACTIVE TRANSPORT EXPERIMENTS  

E-Print Network [OSTI]

ALUMINOSILICATE-COATED SILICA SAND FOR REACTIVE TRANSPORT EXPERIMENTS By JORGE ANTONIO JEREZ transport experiments; Dr. Barbara Williams and Jason Shira from University of Idaho for providing access-COATED SILICA SAND FOR REACTIVE TRANSPORT EXPERIMENTS Abstract by Jorge Antonio Jerez Briones, Ph.D. Washington

Flury, Markus

74

Thermal springs in the Payette River basin, west-central Idaho  

SciTech Connect (OSTI)

The Payette River basin, characterized by steep, rugged mountains and narrow river valleys, occupies an area of about 3300 square miles in west-central Idaho. Predominant rock types in the basin include granitic rocks of the Idaho batholith and basalt flows of the Columbia River Basalt Group. Waters from thermal springs in the basin, temperatures of which range from 34/sup 0/ to 86/sup 0/ Celsius, are sodium bicarbonate type and are slightly alkaline. Dissolved-solids concentrations range from 173 to 470 milligrams per liter. Reservoir temperatures determined from the sodium-potassium-calcium, silicic acid-corrected silica, and sulfate-water isotope geothermometers range from 53/sup 0/ to 143/sup 0/ Celsius. Tritium, present in concentrations between 0 and 2 tritium units, indicate that sampled thermal waters are at least 100 years and possibly more than 1000 years old. Stable-isotope data indicate it is unlikely any of the nonthermal waters sampled are representative of precipitation that recharges the thermal springs in the basin. Thermal springs discharged about 5700 acre-feet of water in 1979. Associated convective heat flux is 1.1 x 10/sup 7/ calories per second.

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

1980-10-01T23:59:59.000Z

75

Thermal extraction analysis of five Los Azufres production wells  

SciTech Connect (OSTI)

Thermal energy extraction from five wells supplying 5-MWe wellhead generators in three zones of the Los Azufres geothermal field has been examined from production and chemical data compiled over 14-years of operation. The data, as annual means, are useful in observing small-scale changes in reservoir performance with continuous production. The chemical components are chloride for quality control and the geothermometer elements for reservoir temperatures. The flowrate and fluid enthalpy data are used to calculate the thermal extraction rates. Integration of these data provides an estimate of the total energy extracted from the zone surrounding the well. The combined production and chemical geothermometer data are used to model the produced fluid as coming from just-penetrating wells for which the annual produced mass originates from a series of concentric hemispheric shells moving out into the reservoir. Estimates are made of the drawdown distance into the reservoir and the far-field conditions.

Kruger, Paul; Quijano, Luis

1995-01-26T23:59:59.000Z

76

Development of Silica Aerogel with Any Density  

E-Print Network [OSTI]

Abstract–New production methods of silica aerogel with high and low refractive indices have been developed. A very slow shrinkage of alcogel at room temperature has made possible producing aerogel with high refractive indices of up to 1.265 without cracks. Even higher refractive indices than 1.08, the transmission length of the aerogel obtained from this technique has been measured to be about 10 to 20 mm at 400 nm wave length. A mold made of alcogel which endures shrinkage in the supercritical drying process has provided aerogel with the extremely low density of 0.009g/cm 3, which corresponds to the refractive index of 1.002. We have succeeded producing aerogel with a wide range of densities. I.

M. Tabata; I. Adachi; T. Fukushima; H. Kawai; H. Kishimoto; A. Kuratani; H. Nakayama; S. Nishida; T. Noguchi; K. Okudaira; Y. Tajima; H. Yano; H. Yokogawa; H. Yoshida

77

Ambient-pressure silica aerogel films  

SciTech Connect (OSTI)

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.

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)

1994-12-31T23:59:59.000Z

78

Laser Damage Precursors in Fused Silica  

SciTech Connect (OSTI)

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.

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

2009-11-11T23:59:59.000Z

79

Luminescent organosilicon polymers and sol-gel synthesis of nano-structured silica  

E-Print Network [OSTI]

filled   hollow   silica   nano-­?   and   microshells  nano-­? extracting  sensor.   Conclusions   The   adsorptive   properties   of   hollow  

Martinez, H. Paul

2011-01-01T23:59:59.000Z

80

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

SciTech Connect (OSTI)

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.

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

1986-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Improvements in geothermometry. Final technical report. Rev  

SciTech Connect (OSTI)

Alkali and alkaline earth geothermometers are useful for estimating geothermal reservoir temperatures, though a general theoretical basis has yet to be established and experimental calibration needs improvement. Equilibrium cation exchange between feldspars provided the original basis for the Na-K and Na-K-Ca geothermometers (Fournier and Truesdell, 1973), but theoretical, field and experimental evidence prove that neither equilibrium nor feldspars are necessary. Here, evidence is summarized in support of these observations, concluding that these geothermometers can be expected to have a surprisingly wide range of applicability, but that the reasons behind such broad applicability are not yet understood. Early experimental work proved that water-rock interactions are slow at low temperatures, so experimental calibration at temperatures below 150/sup 0/ is impractical. Theoretical methods and field data were used instead for all work at low temperatures. Experimental methods were emphasized for temperatures above 150/sup 0/C, and the simplest possible solid and solution compositions were used to permit investigation of one process or question at a time. Unexpected results in experimental work prevented complete integration of the various portions of the investigation.

Potter, J.; Dibble, W.; Parks, G.; Nur, A.

1982-08-01T23:59:59.000Z

82

Cation geothermometry in oil field waters  

SciTech Connect (OSTI)

The assumptions used in the development of cation ratio geothermometers are: (1) the ratios of the cations are controlled by cation exchange between solid silicate phases, (2) aluminum is conserved in the solid phases, and (3) neither hydrogen ions nor CO[sub 2] enter into the net reactions. These assumptions do not apply to oilfield waters where organic species are present and commonly abundant. Nine different published cation geothermometers of Na/K, Na-K-Ca, Na-K-Ca-Mg, and Mg/Li were applied to 309 water samples from both oilfield and geothermal wells. None of the cation geothermometers predicted consistent or accurate temperatures for the oilfield waters. Plots of measured v. predicted temperature for oilfield water samples gave correlation coefficients of less than 0.35. In contrast, those same plots for geothermal water samples within the same temperature range gave correlation coefficients between 0.45 and 0.95. This analysis suggests that the presence of organic species exerts a strong control on the cation ratios. Organic species form complexes of varying stability with the cations. This, in turn, changes the relative concentrations of the cations in solution over that which is expected when cation exchange between silicate phases controls the ratios. Organic complexes also strongly affect pH and P[sub CO[sub 2

Smith, L.K.; Dunn, T.L.; Surdam, R.C. (Univ. of Wyoming, Laramie, WY (United States))

1992-01-01T23:59:59.000Z

83

Quantification of residual stress from photonic signatures of fused silica  

SciTech Connect (OSTI)

A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outer-most pane of Space Shuttle windows made from fused silica. A method and apparatus for calibration of the stress-optic coefficient using four-point bending is discussed. The results are validated on known material (acrylic) and are found to agree with literature values to within 6%. The calibration procedure is then applied to fused-silica specimens and the stress-optic coefficient is determined to be 2.43 ± 0.54 × 10{sup ?12} Pa{sup ?1}. Fused silica specimens containing impacts artificially made at NASA’s Hypervelocity Impact Technology Facility (HIT-F), to simulate damage typical during space flight, are examined. The damage sites are cored from fused silica window carcasses and examined with the GFP. The calibrated GFP measurements of residual stress patterns surrounding the damage sites are presented.

Cramer, K. Elliott; Yost, William T. [NASA Langley Research Center, Hampton, VA 23681 (United States); Hayward, Maurice [College of William and Mary, Williamsburg, VA 23185 (United States)

2014-02-18T23:59:59.000Z

84

Preparation, characterization and applications of monolithic titania-silica aerogels.  

E-Print Network [OSTI]

??In this work, new monolithic titania-silica aerogel materials were developed and evaluated. It started with the synthesis using modified sol-gel processes to obtain crack-free monolithic… (more)

Cao, Shengli

2007-01-01T23:59:59.000Z

85

aminopropyl silica gel: Topics by E-print Network  

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

Summary: We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying...

86

amorphous silica systems: Topics by E-print Network  

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

progress in the development and mass production of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter,...

87

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.

88

Electrospinning of silica nanofibers: characterization and application to biosensing  

E-Print Network [OSTI]

; and the pore size is around several nanometers to a micrometer wide. In this work, the relationship between the diameter of electrospun silica fibers, experimental parameters such as concentration and voltage, and between pore size of the fiber membrane...

Tsou, Pei-Hsiang

2009-06-02T23:59:59.000Z

89

Experimental evaluation of heat transfer characteristics of silica nanofluid  

E-Print Network [OSTI]

The laminar convective heat transfer characteristics were investigated for silica nanofluid. An experimental loop was built to obtain heat transfer coefficients for single-phase nanofluids in a circular conduit in laminar ...

Zhang, Zihao, S.B. Massachusetts Institute of Technology

2010-01-01T23:59:59.000Z

90

Silica Extraction at the Mammoth Lakes Geothermal Site  

SciTech Connect (OSTI)

The purpose of this project is to develop a cost-effective method to extract marketable silica (SiO{sub 2}) from fluids at the Mammoth Lakes, California geothermal power plant. Marketable silica provides an additional revenue source for the geothermal power industry and therefore lowers the costs of geothermal power production. The use of this type of ''solution mining'' to extract resources from geothermal fluids eliminates the need for acquiring these resources through energy intensive and environmentally damaging mining technologies. We have demonstrated that both precipitated and colloidal silica can be produced from the geothermal fluids at Mammoth Lakes by first concentrating the silica to over 600 ppm using reverse osmosis (RO). The RO permeate can be used in evaporative cooling at the plant; the RO concentrate is used for silica and potentially other (Li, Cs, Rb) resource extraction. Preliminary results suggest that silica recovery at Mammoth Lakes could reduce the cost of geothermal electricity production by 1.0 cents/kWh.

Bourcier, W; Ralph, W; Johnson, M; Bruton, C; Gutierrez, P

2006-06-07T23:59:59.000Z

91

Silica recovery and control in Hawaiian geothermal fluids  

SciTech Connect (OSTI)

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.

Thomas, D.M.

1992-06-01T23:59:59.000Z

92

Silica recovery and control in Hawaiian geothermal fluids. Final report  

SciTech Connect (OSTI)

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.

Thomas, D.M.

1992-06-01T23:59:59.000Z

93

Temperature and moisture dependence of dielectric constant for silica aerogels  

SciTech Connect (OSTI)

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.

Hrubesh, L.H., LLNL

1997-03-01T23:59:59.000Z

94

Surface characterization of silica glass substrates treated by atomic hydrogen  

SciTech Connect (OSTI)

Silica glass substrates with very flat surfaces were exposed to atomic hydrogen at different temperatures and durations. An atomic force microscope was used to measure root-mean-square (RMS) roughness and two-dimensional power spectral density (PSD). In the treatment with atomic hydrogen up to 900 °C, there was no significant change in the surface. By the treatment at 1000 °C, the changes in the RMS roughness and the PSD curves were observed. It was suggested that these changes were caused by etching due to reactions of atomic hydrogen with surface silica. By analysis based on the k-correlation model, it was found that the spatial frequency of the asperities became higher with an increase of the treatment time. Furthermore, the data showed that atomic hydrogen can flatten silica glass surfaces by controlling heat-treatment conditions. - Highlights: • Silica glass surface was treated by atomic hydrogen at various temperatures. • Surface roughness was measured by an atomic force microscope. • Roughness data were analyzed by two-dimensional power spectral density. • Atomic hydrogen can flatten silica glass surfaces.

Inoue, Hiroyuki [Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo 153-8505 (Japan); Masuno, Atsunobu, E-mail: masuno@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo 153-8505 (Japan); Ishibashi, Keiji [Canon ANELVA Corporation, Asao-ku, Kawasaki, Kanagawa 215-8550 (Japan); Tawarayama, Hiromasa [Kawazoe Frontier Technologies Corporation, Kuden 931-113, Sakae-ku, Yokohama, Kanagawa 247-0014 (Japan); Zhang, Yingjiu; Utsuno, Futoshi [Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo 153-8505 (Japan); Koya, Kazuo; Fujinoki, Akira [Shin Etsu Quartz Prod. Co., Ltd., Res and Applicat Lab, Fukushima 963-0725 (Japan); Kawazoe, Hiroshi [Kawazoe Frontier Technologies Corporation, Kuden 931-113, Sakae-ku, Yokohama, Kanagawa 247-0014 (Japan)

2013-12-15T23:59:59.000Z

95

Vanadyl tert-Butoxy Orthosilicate, OV[OSi(OtBu)3]3: A Model for Isolated Vanadyl Sites on Silica and a  

E-Print Network [OSTI]

-containing silica aerogels and xerogels.13-17 In addition, vanadia-silica catalysts have been prepared by treating

Iglesia, Enrique

96

Silica membranes for hydrogen separation from coal gas. Final report  

SciTech Connect (OSTI)

This project is a continuation of a previous DOE-UCR project (DE-FG22- 89PC89765) dealing with the preparation of silica membranes highly permselective to hydrogen at elevated temperatures, suitable for hydrogen separation from coal gas. The membranes prepared in the previous project had very high selectivity but relatively low permeance. Therefore, the general objectives of this project were to improve the permeance of these membranes and to obtain fundamental information about membrane structure and properties. The specific objectives were: (1) to explore new silylation reagents and reaction conditions with the purpose of reducing the thickness and increasing the permeance of silica membranes prepared by chemical vapor deposition (CVD), (2) to characterize the membrane structure, (3) to delineate mechanism and kinetics of deposition, (4) to measure the permeability of silica layers at different extents of deposition, and (5) to mathematically model the relationship between structure and deposition kinetics.

Gavalas, G.R.

1996-01-01T23:59:59.000Z

97

E-Print Network 3.0 - aqueous silica sols Sample Search Results  

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

by supercritical CO2 extraction of silica sol-gels.14 But the very high porosity in aerogels contributes... Silica Monoliths Templated on L3 Liquid Crystal Abds-Sami Malik,,...

98

Experimental Simulation of Evaporation-Driven Silica Sinter Formation and Microbial Silicification in Hot Spring Systems  

E-Print Network [OSTI]

in geothermal waters after they have reached the surface. Water evaporation is, along with cooling, one Evaporation of silica-rich geothermal waters is one of the main abiotic drivers of the formation of silica

Paris-Sud XI, Université de

99

Evaluation and recommendations for reduction of a silica dust exposure  

E-Print Network [OSTI]

to the increase in active tuberculosis among silicotics previously discussed. Perhaps there is a synergistic effect between silicosis and various lung cancers. A 1999 paper by Checkoway("6) showed a significantly (p=0. 02) increasing trend of lung cancer..., and that 100, 000 are exposed to silica dust through sandblasting, rock drilling and mining operations. &sI Silica is the second- most-common mineral in the earth's crust and a major component of sand, rock and mineral ores so it is not surprising to find...

Gruben, Raymond L

2000-01-01T23:59:59.000Z

100

Project EARTH-11-RR4: Reconstructing the Cenozoic Silica Cycle using Sponge 30  

E-Print Network [OSTI]

to the oceans and the success of the diatoms. Although diversity curves suggest that diatoms radiated concident. The radiation of siliceous diatoms during the Cenozoic is thought to have forced the ocean from a high silica.e. enhanced silicate weathering due to the radiation of grasses on land drove increased silica supply

Henderson, Gideon

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness, and Strength  

E-Print Network [OSTI]

Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness algae that is mainly composed of amorphous silica, which features a hierarchical structure that ranges in diatom algae as a basis to study a bioinspired nanoporous material implemented in crystalline silica. We

Buehler, Markus J.

102

Analysis of the elastic behaviour of silica aerogels taken as a percolating system  

E-Print Network [OSTI]

289 Analysis of the elastic behaviour of silica aerogels taken as a percolating system T. Woignier of silica aerogels are performed using the three points flexural technique. The elastic behaviour is studied measurement - for silica aerogels. These highly porous materials are obtained from a sol-gel process. Solvent

Paris-Sud XI, Université de

103

Multicomponent Transport of Sulfate in a Goethite-Silica Sand System  

E-Print Network [OSTI]

Multicomponent Transport of Sulfate in a Goethite-Silica Sand System at Variable pH and Ionic of protons and sulfate on goethite and silica were used in combination with a one-dimensional mass-transport model to predict the transport of sulfate at variable pH and ionic strength in a goethite-silica system

Sparks, Donald L.

104

Synthesis of highly ordered mesoporous silica materials using sodium silicate and amphiphilic block copolymers  

E-Print Network [OSTI]

Synthesis of highly ordered mesoporous silica materials using sodium silicate and amphiphilic block) structures, using sodium silicate as the silica source and amphiphilic block copolymers as the structure of mesoporous silica material using nonionic surfac- tant and sodium silicate in the pH range 3­10.5. However

Kim, Ji Man

105

Coagulation chemistries for silica removal from cooling tower water.  

SciTech Connect (OSTI)

The formation of silica scale is a problem for thermoelectric power generating facilities, and this study investigated the potential for removal of silica by means of chemical coagulation from source water before it is subjected to mineral concentration in cooling towers. In Phase I, a screening of many typical as well as novel coagulants was carried out using concentrated cooling tower water, with and without flocculation aids, at concentrations typical for water purification with limited results. In Phase II, it was decided that treatment of source or make up water was more appropriate, and that higher dosing with coagulants delivered promising results. In fact, the less exotic coagulants proved to be more efficacious for reasons not yet fully determined. Some analysis was made of the molecular nature of the precipitated floc, which may aid in process improvements. In Phase III, more detailed study of process conditions for aluminum chloride coagulation was undertaken. Lime-soda water softening and the precipitation of magnesium hydroxide were shown to be too limited in terms of effectiveness, speed, and energy consumption to be considered further for the present application. In Phase IV, sodium aluminate emerged as an effective coagulant for silica, and the most attractive of those tested to date because of its availability, ease of use, and low requirement for additional chemicals. Some process optimization was performed for coagulant concentration and operational pH. It is concluded that silica coagulation with simple aluminum-based agents is effective, simple, and compatible with other industrial processes.

Nyman, May Devan; Altman, Susan Jeanne; Stewart, Tom

2010-02-01T23:59:59.000Z

106

Silica dust control when drilling concrete Page 1 of 2  

E-Print Network [OSTI]

Silica dust control when drilling concrete Page 1 of 2 Drilling into concrete releases a fine sandy and routinely drill into concrete are at risk of developing this disease. Controlling the dust Hammer drills are available with attached dust removal systems. These draw dust from the drill end, down the attachment

Knowles, David William

107

High temperature thermographic measurements of laser heated silica  

SciTech Connect (OSTI)

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.

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

2009-11-02T23:59:59.000Z

108

Fractal Studies on Titanium-Silica Aerogels using SMARTer  

SciTech Connect (OSTI)

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.

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)

2008-03-17T23:59:59.000Z

109

Spatial Pattern Formation in Fused Silica Under UV Irradiation  

E-Print Network [OSTI]

Spatial Pattern Formation in Fused Silica Under UV Irradiation Problem Presenter Leslie Button lenses gradually degrades and ultimately damages these optical components. Corning is a global supplier of optical and ceramic materials across various industries and is particularly interested in this damage

Edwards, David A.

110

Development of Silica/Vanadia/ Titania Catalysts for Removal of  

E-Print Network [OSTI]

mercury (Hg0) from simulated coal-combustion flue gas. Experiments were carried out in fixed-bed reactorsDevelopment of Silica/Vanadia/ Titania Catalysts for Removal of Elemental Mercury from Coal-Combustion the composition and microstructures of SCR (selective catalytic reduction) catalysts for Hg0 oxidation in coal-combustion

Li, Ying

111

Moisture Transport in Silica Gel Packed Beds: II. Experimental Study  

SciTech Connect (OSTI)

Experiments have been performed to obtain the transient response of a thin adiabatic packed bed of silica gel after a step change in inlet air conditions, comparisons are made with predictions using a solid-side resistance model and a pseudo-gas-side controlled model and better agreement obtained with the former model.

Pesaran, A. A.; Mills, A. F.

1986-08-01T23:59:59.000Z

112

Flue gas injection control of silica in cooling towers.  

SciTech Connect (OSTI)

Injection of CO{sub 2}-laden flue gas can decrease the potential for silica and calcite scale formation in cooling tower blowdown by lowering solution pH to decrease equilibrium calcite solubility and kinetic rates of silica polymerization. Flue gas injection might best inhibit scale formation in power plant cooling towers that use impaired makeup waters - for example, groundwaters that contain relatively high levels of calcium, alkalinity, and silica. Groundwaters brought to the surface for cooling will degas CO{sub 2} and increase their pH by 1-2 units, possibly precipitating calcite in the process. Recarbonation with flue gas can lower the pHs of these fluids back to roughly their initial pH. Flue gas carbonation probably cannot lower pHs to much below pH 6 because the pHs of impaired waters, once outgassed at the surface, are likely to be relatively alkaline. Silica polymerization to form scale occurs most rapidly at pH {approx} 8.3 at 25 C; polymerization is slower at higher and lower pH. pH 7 fluids containing {approx}220 ppm SiO{sub 2} require > 180 hours equilibration to begin forming scale whereas at pH 8.3 scale formation is complete within 36 hours. Flue gas injection that lowers pHs to {approx} 7 should allow substantially higher concentration factors. Periodic cycling to lower recoveries - hence lower silica concentrations - might be required though. Higher concentration factors enabled by flue gas injection should decrease concentrate volumes and disposal costs by roughly half.

Brady, Patrick Vane; Anderson, Howard L., Jr.; Altman, Susan Jeanne

2011-06-01T23:59:59.000Z

113

INSTRUMENTS-METHODS-36 Absorption and scattering lengths of high density silica aerogels with n = 1.07  

E-Print Network [OSTI]

angles could be the use of silica aerogels as radiator. Simultaneously, an aerogel ?erenkov counter is

L. Debenjak; P. Achenbach; J. Pochodzalla; T. Saito

114

Fluorescent Functionalized Mesoporous Silica for Radioactive Material Extraction  

SciTech Connect (OSTI)

Mesoporous silica with covalently bound salicylic acid molecules incorporated in the structure was synthesized with a one-pot, co-condensation reaction at room temperature. The as-synthesized material has a large surface area, uniform particle size, and an ordered pore structure as determined by characterization with transmission electron microscopy, thermal gravimetric analysis, and infrared spectra, etc. Using the strong fluorescence and metal coordination capability of salicylic acid, functionalized mesoporous silica (FMS) was developed to track and extract radionuclide contaminants, such as uranyl [U(VI)] ions encountered in subsurface environments. Adsorption measurements showed a strong affinity of the FMS toward U(VI) with a Kd value of 105 mL/g, which is four orders of magnitude higher than the adsorption of U(VI) onto most of the sediments in natural environments. The new materials have a potential for synergistic environmental monitoring and remediation of the radionuclide U(VI) from contaminated subsurface environments.

Li, Juan; Zhu, Kake; Shang, Jianying; Wang, Donghai; Nie, Zimin; Guo, Ruisong; Liu, Chongxuan; Wang, Zheming; Li, Xiaolin; Liu, Jun

2012-08-01T23:59:59.000Z

115

Silica aerogels modified by functional and nonfunctional organic groups  

SciTech Connect (OSTI)

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.

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

1996-12-31T23:59:59.000Z

116

1 LOST PRODUCTION AS CONSEQUENSE OF SILICA SCALING IN CERRO  

E-Print Network [OSTI]

Mineral scale depositation occurs in many of the Cerro Prieto wells, but the main problems occurs by silica (SiO2) scale both pipes and reservoir zones close to the downhole. In Cerro Prieto geothermal field three types of scales are found; calcium carbonate (calcite), amorphous silica (SiO2), and metallic sulfides (mainly iron, and lesser lead and cooper). The scale causes lost production and it is necessary to make around 12 workover each year to recover the steam lost. When scaling problems occurred inside casing production is more easier to recover the production that scaling occurred in the reservoir zones, because it caused a skin damage (permeability decrease) in the reservoir zones close to the bottomhole. This paper analyze and discus the scaling problems and discuss the task developed to avoid and minimized the decline wells production, as to recover the production using workover alternatives.

Prieto Geothermal; Wells Mexico; Juan De; Dios Ocampo; Díaz Sara; Lilia Moya; Jesús De; León Vivar

117

Molecular engineering of porous silica using aryl templates  

DOE Patents [OSTI]

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.

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

1994-06-14T23:59:59.000Z

118

Molecular engineering of porous silica using aryl templates  

DOE Patents [OSTI]

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.

Loy, Douglas A. (Albuquerque, NM); Shea, Kenneth J. (Irvine, CA)

1994-01-01T23:59:59.000Z

119

Method for dissolution and stabilization of silica-rich fibers  

DOE Patents [OSTI]

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.

Jantzen, C.M.

1997-11-11T23:59:59.000Z

120

Supercritical carbon dioxide behavior in porous silica aerogel  

SciTech Connect (OSTI)

Analysis of the tails of the small-angle neutron scattering (SANS) intensities relevant to samples formed by porous silica and carbon dioxide at pressures ranging from 0 to 20 MPa and at temperatures of 308 and 353 K confirms that the CO2 fluid must be treated as a two-phase system. The first of these phases is formed by the fluid closer to the silica wall than a suitable distance [delta] and the second by the fluid external to this shell. The sample scattering-length densities and shell thicknesses are determined by the Porod invariants and the oscillations observed in the Porod plots of the SANS intensities. The resulting matter densities of the shell regions (thickness 15-35 {angstrom}) are approximately equal, while those of the outer regions increase with pressure and become equal to the bulk CO2 at the higher pressures only in the low-temperature case.

Ciccariello, Salvino [Universita di Padova; Melnichenko, Yuri B [ORNL; He, Lilin [ORNL

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Process for manufacturing hollow fused-silica insulator cylinder  

DOE Patents [OSTI]

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.

Sampayan, Stephen E. (Manteca, CA); Krogh, Michael L. (Lee's Summit, MO); Davis, Steven C. (Lee's Summit, MO); Decker, Derek E. (Discovery Bay, CA); Rosenblum, Ben Z. (Overland Park, KS); Sanders, David M. (Livermore, CA); Elizondo-Decanini, Juan M. (Albuquerque, NM)

2001-01-01T23:59:59.000Z

122

Silica aerogel: An intrinsically low dielectric constant material  

SciTech Connect (OSTI)

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.

Hrubesh, L.W.

1995-04-01T23:59:59.000Z

123

Measurement of Radiation Damage on Silica Aerogel Cerenkov Radiator  

E-Print Network [OSTI]

We measured the radiation damage on silica aerogel Cerenkov radiators originally developed for the B-factory experiment at KEK. Refractive index of the aerogel samples ranged from 1.012 to 1.028. The samples were irradiated up to 9.8 MRad of equivalent dose. Measurements of transmittance and refractive index were carried out and these samples were found to be radiation hard. Deteriorations in transparency and changes of refractive index were observed to be less than 1.3% and 0.001 at 90% confidence level, respectively. Prospects of using aerogels under high-radiation environment are discussed. 1 Introduction Silica aerogels(aerogels) are a colloidal form of glass, in which globules of silica are connected in three dimensional networks with siloxan bonds. They are solid, very light, transparent and their refractive index can be controlled in the production process. Many high energy and nuclear physics experiments have used aerogels instead of pressurized gas for their Cerenkov coun...

Belle Preprint; Sahu Wang; M. Z. Wang; R. Suda; R. Enomoto; K. C. Peng; C. H. Wang; I. Adachi; M. Amami

124

Multimodality Imaging with Silica-Based Targeted Nanoparticle Platforms  

SciTech Connect (OSTI)

Objectives: To synthesize and characterize a C-Dot silica-based nanoparticle containing 'clickable' groups for the subsequent attachment of targeting moieties (e.g., peptides) and multiple contrast agents (e.g., radionuclides with high specific activity) [1,2]. These new constructs will be tested in suitable tumor models in vitro and in vivo to ensure maintenance of target-specificity and high specific activity. Methods: Cy5 dye molecules are cross-linked to a silica precursor which is reacted to form a dye-rich core particle. This core is then encapsulated in a layer of pure silica to create the core-shell C-Dot (Figure 1) [2]. A 'click' chemistry approach has been used to functionalize the silica shell with radionuclides conferring high contrast and specific activity (e.g. 64Cu and 89Zr) and peptides for tumor targeting (e.g. cRGD and octreotate) [3]. Based on the selective Diels-Alder reaction between tetrazine and norbornene, the reaction is bioorthogonal, highyielding, rapid, and water-compatible. This radiolabeling approach has already been employed successfully with both short peptides (e.g. octreotate) and antibodies (e.g. trastuzumab) as model systems for the ultimate labeling of the nanoparticles [1]. Results: PEGylated C-Dots with a Cy5 core and labeled with tetrazine have been synthesized (d = 55 nm, zeta potential = -3 mV) reliably and reproducibly and have been shown to be stable under physiological conditions for up to 1 month. Characterization of the nanoparticles revealed that the immobilized Cy5 dye within the C-Dots exhibited fluorescence intensities over twice that of the fluorophore alone. The nanoparticles were successfully radiolabeled with Cu-64. Efforts toward the conjugation of targeting peptides (e.g. cRGD) are underway. In vitro stability, specificity, and uptake studies as well as in vivo imaging and biodistribution investigations will be presented. Conclusions: C-Dot silica-based nanoparticles offer a robust, versatile, and multi-functional platform to enhance in vivo detection sensitivity and non-invasively assay receptor expression/status of tumor cellular targets, including those of low abundance, using nuclear-NIR fluorescence imaging approaches [2]. Improvements in molecular diagnostics, refined by the availability of nanotechnology platforms, will be a key determinant in driving early-stage disease detection and prevention, ultimately leading to decreases in mortality.

Jason S. Lewis

2012-04-09T23:59:59.000Z

125

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

DOE Patents [OSTI]

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.

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

2013-02-26T23:59:59.000Z

126

Extensional rheology of shear-thickening fumed silica nanoparticles dispersed in an aqueous polyethylene  

E-Print Network [OSTI]

polyethylene oxide solution Sunilkumar Khandavalli and Jonathan P. Rothsteina) Mechanical and Industrial rheology of fumed silica nanoparticles dispersed in an aqueous polyethylene oxide (PEO) solution

Rothstein, Jonathan

127

Biotransformation of Two-Line Silica-Ferrihydrite by a Dissimilatory...  

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

by a Dissimilatory Fe(III)-Reducing Bacterium: Formation of Carbonate Green Biotransformation of Two-Line Silica-Ferrihydrite by a Dissimilatory Fe(III)-Reducing...

128

Sol-Gel Mesoporous Silica Aerogels and Bio Hybrids for Functional Applications.  

E-Print Network [OSTI]

??The thesis covers a systematic investigation on the synthesis of silica aerogels and microspheres with tailored porosity, at ambient conditions by varying the experimental parameters… (more)

Smitha, Sasidharan

2009-01-01T23:59:59.000Z

129

E-Print Network 3.0 - acid-modified silica nanoparticles Sample...  

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

as 3D Scaffolds for New Materials: from Mechanically Strong Polymer Crosslinked Aerogels Summary: of X-aerogels where skeletal inorganic nanoparticles (e.g., silica and >30...

130

E-Print Network 3.0 - amorphous silica exposed Sample Search...  

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

> >> Page: << < 1 2 3 4 5 > >> 81 Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky* Summary: fundamental...

131

TESLA-FEL 2004-01 Silica Aerogel Radiators for Bunch Length Measurements ?  

E-Print Network [OSTI]

Cherenkov radiators based on Silica aerogel are used to measure the electron bunch length at the photo injector test facility at DESY Zeuthen (PITZ). The energy range of those electrons is 4-5 MeV. In this paper the time resolution defined by the usage of aerogel is calculated analytically and Monte Carlo simulations are performed. It is shown that Silica aerogel gives the possibility to reach a time resolution of about 0.1 ps for high photon intensities and a time resolution of about 0.02 ps can be obtained for thin Silica aerogel radiators. Key words: silica aerogel, bunch length, time resolution, PITZ 1

J. Bähr A; V. Djordjadze A; D. Lipka A; A. Onuchin B; F. Stephan A

132

E-Print Network 3.0 - acid functionalized silica Sample Search...  

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

Materials Science ; Engineering 18 The influence of void space on antireflection coatings of silica nanoparticle self-assembled films Summary: nanoparticles on a silver...

133

E-Print Network 3.0 - amine catalyzed silica Sample Search Results  

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

the elastic modulus with epoxy loading, for an epoxy- crosslinked, amine-modified silica aerogel. Those... authors argued that the epoxy bridges the neighboring amine- modified...

134

E-Print Network 3.0 - acid modified silica Sample Search Results  

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

the elastic modulus with epoxy loading, for an epoxy- crosslinked, amine-modified silica aerogel. Those... authors argued that the epoxy bridges the neighboring amine- modified...

135

Accelerated test methods for evaluating alkali-silica reactivity of recycled concrete aggregates.  

E-Print Network [OSTI]

??This thesis reports the findings of a study carried out to determine the effectiveness of Accelerated Tests in evaluating the Alkali-Silica Reactivity of Recycled Concrete… (more)

Johnson, Robert C (Author)

2011-01-01T23:59:59.000Z

136

Synthesis of Mesocellular Silica Foams with Tunable Window and Cell Dimensions  

E-Print Network [OSTI]

Polystyrene microspheres coated with cationic surfactants are easily prepared by micro- emulsion templates. These silica foams resemble dense aerogels. Introduction Because of their greatly enhanced pore

Yang, Peidong

137

E-Print Network 3.0 - ash slag silica Sample Search Results  

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

Engineering ; Materials Science 91 By-Products Utilization Summary: pozzolans include coal fly ash, blast furnace slag, silica fume, and other combustion ashes. When...

138

Construction of a multi-functional cryogenic propellant tank with cross-linked silica aerogel.  

E-Print Network [OSTI]

??Aerogels are low-density nanostructured porous materials, whose practical applications have been limited by their poor mechanical properties. Crosslinking the nanoparticle building blocks of silica aerogels… (more)

Reinheimer, Preston Glenn

2010-01-01T23:59:59.000Z

139

Polymer reinforced aerogels and composites A. Polyimide crosslinked aerogels B. Silica-polymethylmethacrylate composites .  

E-Print Network [OSTI]

??"Crosslinking of aerogels is a promising approach to combine the advantages of inorganic and polymeric materials. In the present study, two types of polyimide-silica hybrid… (more)

Patil, Vishal U., 1981-

2008-01-01T23:59:59.000Z

140

Favorable Geochemistry from Springs and Wells in COlorado  

SciTech Connect (OSTI)

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

Zehner, Richard E.

2012-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Thermal annealing of laser damage precursors on fused silica surfaces  

SciTech Connect (OSTI)

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.

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

2012-03-19T23:59:59.000Z

142

Association of length-slow silica with evaporites  

SciTech Connect (OSTI)

In 1971, Folk and Pittman described the common occurrence of length-slow quartz (or lutecite) with evaporitic minerals, and they suggested that lutecite might be a useful indicator for vanished evaporites. However, the subsequent discoveries of length-slow silica in carbonate turbidites and in abyssal Pacific cherts revealed that lutecite is not restricted to near-surface deposits. Moreover, Kastner found that length-slow quartz could be crystallized in slightly alkaline solutions enriched in Mg[sup 2+], Na[sup +], and SO[sub 4][sup [minus]2]. Following these studies, researchers have cited the presence of lutecite in rock samples as suggestive but not compelling evidence for an evaporitic origin, and the precise nature of this form of silica has remained somewhat enigmatic. Investigations of chert nodules from evaporitic and non-evaporitic regimes support an identification of length-slow quartz'' with the mineral moganite, a polymorph of silica that is fibrous and optically length slow. Results are based upon X-ray powder diffraction of the chert, followed by Rietveld refinement of the X-ray patterns to quantify the weight fraction of quartz and moganite in each specimen. Most non-evaporitic chert appears to contain between 5 and 15 wt. % moganite, but evaporitic cherts often contain more than 20 wt. %. Cherts that have transformed from precursor magadiite can be particularly rich in moganite; samples from Lake Magadi, Kenya and from Harney Lake, Oregon revealed about equal parts moganite and quartz. However, the observation of decreasing abundances of moganite in rocks of increasing age indicates that moganite is metastable relative to quartz.

Heaney, P.J. (Princeton Univ., Princeton, NJ (United States). Dept. of Geology); Sheppard, R.A. (Geological Survey, Denver, CO (United States). Denver Federal Center); Post, J.E. (Smithsonian Inst., Washington, DC (United States). Dept. of Mineral Sciences)

1992-01-01T23:59:59.000Z

143

Chemical treatment for silica-containing glass surfaces  

DOE Patents [OSTI]

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.

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

1998-04-07T23:59:59.000Z

144

Chemical treatment for silica-containing glass surfaces  

DOE Patents [OSTI]

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.

Grabbe, Alexis (Albuquerque, NM); Michalske, Terry Arthur (Bernalillo, NM); Smith, William Larry (Albuquerque, NM)

1999-01-01T23:59:59.000Z

145

Method for chemical surface modification of fumed silica particles  

DOE Patents [OSTI]

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.

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

1999-05-11T23:59:59.000Z

146

Chemical treatment for silica-containing glass surfaces  

DOE Patents [OSTI]

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.

Grabbe, Alexis (Albuquerque, NM); Michalske, Terry Arthur (Cedar Crest, NM); Smith, William Larry (Albuquerque, NM)

1999-01-01T23:59:59.000Z

147

Method for chemical surface modification of fumed silica particles  

DOE Patents [OSTI]

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.

Grabbe, Alexis (Albuquerque, NM); Michalske, Terry Arthur (Cedar Crest, NM); Smith, William Larry (Albuquerque, NM)

1999-01-01T23:59:59.000Z

148

Chemical treatment for silica-containing glass surfaces  

DOE Patents [OSTI]

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.

Grabbe, Alexis (Albuquerque, NM); Michalske, Terry Arthur (Cedar Crest, NM); Smith, William Larry (Albuquerque, NM)

1998-01-01T23:59:59.000Z

149

Optical and radiographical characterization of silica aerogel for Cherenkov radiator  

E-Print Network [OSTI]

We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying method enables us to produce highly transparent hydrophobic aerogels with high refractive index by shrinking wet-gels. In order to investigate the uniformity in the density (i.e., refractive index) of an individual aerogel monolith, we use the laser Fraunhofer method, an X-ray absorption technique, and Cherenkov imaging by a ring imaging Cherenkov detector in a beam test. We observed an increase in density at the edge of the aerogel tiles, produced by pin-drying.

Tabata, Makoto; Hatakeyama, Yoshikiyo; Kawai, Hideyuki; Morita, Takeshi; Nishikawa, Keiko

2012-01-01T23:59:59.000Z

150

Optical and radiographical characterization of silica aerogel for Cherenkov radiator  

E-Print Network [OSTI]

We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying method enables us to produce highly transparent hydrophobic aerogels with high refractive index by shrinking wet-gels. In order to investigate the uniformity in the density (i.e., refractive index) of an individual aerogel monolith, we use the laser Fraunhofer method, an X-ray absorption technique, and Cherenkov imaging by a ring imaging Cherenkov detector in a beam test. We observed an increase in density at the edge of the aerogel tiles, produced by pin-drying.

Makoto Tabata; Ichiro Adachi; Yoshikiyo Hatakeyama; Hideyuki Kawai; Takeshi Morita; Keiko Nishikawa

2012-07-17T23:59:59.000Z

151

Measurement of Radiation Damage on Silica Aerogel \\v Cerenkov Radiator  

E-Print Network [OSTI]

We measured the radiation damage on silica aerogel \\v Cerenkov radiators originally developed for the $B$-factory experiment at KEK. Refractive index of the aerogel samples ranged from 1.012 to 1.028. The samples were irradiated up to 9.8~MRad of equivalent dose. Measurements of transmittance and refractive index were carried out and these samples were found to be radiation hard. Deteriorations in transparency and changes of refractive index were observed to be less than 1.3\\% and 0.001 at 90\\% confidence level, respectively. Prospects of using aerogels under high-radiation environment are discussed.

S. K. Sahu et al

1996-04-11T23:59:59.000Z

152

The production of activated silica with carbon dioxide gas  

E-Print Network [OSTI]

Ional to the per cent of carbon dioxi. de 1n the flue gas for a constant total gas flow rate. REFE REN CES l. Andrews, R. V, , Hanford Works Eocument (1952), 2. Andrews, R. V. & J. A. W. W. A, , ~46 82 (1954). 3. Andrews, R. V, , Personal Communication 4... of the reciuire . ents for the dedree of iliASTER OF SCIENCE Janus', 1956 Major Subject: Chemi. cal Engineering TH PRODUCTION OP ACTIVATED SILICA 7iIITH CARBON DIOXIDE GAS A Thesis William Bell Hayes III Approved as to style and content by: Chairmen...

Hayes, William Bell

1956-01-01T23:59:59.000Z

153

Silica Supported Ceria Nanoparticles: A Hybrid Nanostructure To Increase  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systemsBi (2)Sharing Smart GridShift EndSidneyChemistry » Silica

154

Preparation of silica aerogels with improved mechanical properties and extremely low thermal conductivities through modified sol-gel process  

E-Print Network [OSTI]

Reported silica aerogels have a thermal conductivity as low as 15 mW/mK. The fragility of silica aerogels, however, makes them impractical for structural applications. The purpose of the study is to improve the ductility ...

Zuo, Yanjia

2010-01-01T23:59:59.000Z

155

Preparation of silica aerogels with improved mechanical properties and extremely low thermal conductivities through modified sol-gel process .  

E-Print Network [OSTI]

??Reported silica aerogels have a thermal conductivity as low as 15 mW/mK. The fragility of silica aerogels, however, makes them impractical for structural applications. The… (more)

Zuo, Yanjia

2010-01-01T23:59:59.000Z

156

Ethylenediamine at Air/Liquid and Air/Silica Interfaces: Protonation  

E-Print Network [OSTI]

surface and EDA protonated products at air/liquid interfaces. The SFG spectra of EDA adsorbedEthylenediamine at Air/Liquid and Air/Silica Interfaces: Protonation Versus Hydrogen BondingKa (HOSit)) is between the two pKa values of EDA (in the range of 7.56-10.71) at the air/silica interface

157

DOI: 10.1002/adma.200701303 Nanolayered Carbon/Silica Superstructures via Organosilane  

E-Print Network [OSTI]

. A main advantage using mesoporous silica is to synthesize carbon/silica composite materials with tunable of amorphous carbon materials after carbonization, and uncontrolled morphologies of composite materials is typically high. However, the composites are not uniform; car- bonization mainly produces amorphous carbon

Zhu, Yuntian T.

158

Density hysteresis of heavy water confined in a nanoporous silica matrix  

E-Print Network [OSTI]

Density hysteresis of heavy water confined in a nanoporous silica matrix Yang Zhanga,b , Antonio of heavy water confined in a nanoporous silica matrix in a temperature-pressure range, from 300 to 130 K in the relevant phase region. More- over, the density data we obtained for the confined heavy water under

Chen, Sow-Hsin

159

Friction and Heat Transfer Characteristics of Silica and CNT Nanofluids in a Tube Flow  

E-Print Network [OSTI]

Friction and Heat Transfer Characteristics of Silica and CNT Nanofluids in a Tube Flow MILIVOJE M@niu.edu * www.kostic.niu.edu Abstract: - An apparatus for exploring friction and heat transfer characteristics flow. Initial turbulent friction and heat transfer measurements for silica and carbon nanotube (CNT

Kostic, Milivoje M.

160

The size and polydispersity of silica nanoparticles under simulated hot spring conditions  

E-Print Network [OSTI]

-through geothermal simu- lator system where polymerization was induced by rapid cooling. Changes in [SiO2], IS of silica nanoparticles in supersaturated geothermal waters was simulated using a flow-through geothermal of silica in active geothermal systems is a well-known process leading to the silicification

Benning, Liane G.

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Mechanism of Elongation of Gold or Silver Nanoparticles in Silica by Irradiation with Swift Heavy Ions  

E-Print Network [OSTI]

1 Mechanism of Elongation of Gold or Silver Nanoparticles in Silica by Irradiation with Swift Heavy nanoparticles oriented parallel to one another can be synthesized in SiO2 by ion irradiation. Our aim, silica glass 1. Introduction Well-defined Au nanoparticles and nanorods are desirable for their optical

Boyer, Edmond

162

The onset of optical breakdown in KrF-laser-irradiated silica glass surfaces  

E-Print Network [OSTI]

A synthetic fused silica obtained from Tosoh SGM Co., ESL-1000 (OH % 1200 wt. ppm), with a thick- ness of 2 mmThe onset of optical breakdown in KrF-laser-irradiated silica glass surfaces Y. Kawaguchia,* , A Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 5, 1

Dickinson, J. Thomas

163

Surface Analysis of Silica Gel Particles after Mechanical Dry Coating with Magnesium Stearate  

E-Print Network [OSTI]

1 Surface Analysis of Silica Gel Particles after Mechanical Dry Coating with Magnesium Stearate particles (d50 = 55 µm) by coating with different mass ratios of magnesium stearate - MgSt2 (d50 = 4.6 µm Group). Keywords: AFM phase imaging, adhesion force, dry coating, silica, magnesium stearate. 1

Paris-Sud XI, Université de

164

Pulsed infrared laser annealing of gold nanoparticles embedded in a silica A. Halabica,1,a  

E-Print Network [OSTI]

Pulsed infrared laser annealing of gold nanoparticles embedded in a silica matrix A. Halabica,1,a J; published online 28 April 2008 Pulsed infrared laser irradiation was used to modify the optical and physical in a fused-silica matrix. The experiments demonstrate the unique effects of fast thermal heating

Pennycook, Steve

165

ORIGINAL PAPER Algal-silica cycling and pigment diagenesis in recent alpine  

E-Print Network [OSTI]

dis- solved within 50 years of deposition. Diatom dissolu- tion, silica recycling, and diageneticO2, hereafter BSi) in lake sediments that has led to their common use in freshwater paleoecology have the lowest preservation potential for diatom frustules. However, the recycling of diatom silica

Konhauser, Kurt

166

Stress dependent activation entropy for dynamic fatigue of pristine silica optical fibers  

E-Print Network [OSTI]

Subcritical crack growth in fused silica is treated as a stress assisted chemical reaction between water distilled water and pH 7 buffer solution, and the results are found to be similar. The fatigue parameters to the barrier height. The results show subcritical crack growth in high strength silica is dominated by entropy

Matthewson, M. John

167

Hybrid structure laser based on semiconductor nanowires and a silica microfiber knot cavity  

E-Print Network [OSTI]

Hybrid structure laser based on semiconductor nanowires and a silica microfiber knot cavity Qing://apl.aip.org/about/rights_and_permissions #12;Hybrid structure laser based on semiconductor nanowires and a silica microfiber knot cavity Qing 2009 We demonstrate a hybrid structure laser consisting of a single or multiple zinc oxide Zn

Wu, Shin-Tson

168

Hybrid Silica-PVA Nanofibers via Sol-Gel Electrospinning Tahira Pirzada,,  

E-Print Network [OSTI]

Hybrid Silica-PVA Nanofibers via Sol-Gel Electrospinning Tahira Pirzada,,§ Sara A. Arvidson,,§ Carl: We report on the synthesis of poly(vinyl alcohol) (PVA)-silica hybrid nanofibers via sol-gel electro is under- taken and reveals a composition window in which defect-free hybrid nanofibers with diameters

Khan, Saad A.

169

Integrated Optical Orbital Angular Momentum Multiplexing Device using 3-D Waveguides and a Silica PLC  

E-Print Network [OSTI]

PLC Binbin Guan,1 Ryan P. Scott,1 Nicolas K. Fontaine,2 Tiehui Su,1 Carlo Ferrari,3 Mark Cappuzzo,3 on a silica planar lightwave circuit (PLC) coupled to a 3-D photonic circuit that efficiently generates planar lightwave circuit (PLC) with a silica 3-D PIC that supports up to 15 OAM modes, both TE and TM

Yoo, S. J. Ben

170

Preparation of Micrometer-to Sub-micrometer-Sized Nanostructured Silica Particles Using High-Energy Ball Milling  

E-Print Network [OSTI]

, mesoporous silica synthesized in the form of thin films,3 aerogels,4 and particles are the most cited

Mitchell, Brian S.

171

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

SciTech Connect (OSTI)

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.

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

2011-03-20T23:59:59.000Z

172

Dielectric and magnetic properties of some gadolinium silica nanoceramics  

SciTech Connect (OSTI)

Some nanostructure gadolinium silica glass-ceramics were obtained undergoing a sol gel method and a heat-treatment at 1000°C about two hours. The magnetic and dielectric properties of these samples were studied. The magnetic properties were evidenced performing susceptibility measurements in the 80-300K temperature range. A Curie-Weiss behavior has acquired. The values estimated for paramagnetic Curie temperature being small and positive suggest the presence of weak ferromagnetic interactions between Gd{sup 3+} ions. The dielectric properties were evaluated from dielectric permittivity (?{sub r}) and dielectric loss (tan?) measurements at the frequency 1 kHz, 10 kHz and 100 kHz, in the 25-225°C temperature range and dielectric dispersion at room temperature for 79.5 kHz - 1GHz frequency area. The dielectric properties suggest that the main polarization mechanism corresponds to interfacial polarization, characteristic for polycrystalline-structured dielectrics. The polycrystalline structure of the samples is due to the polymorphous transformations of the nanostructure silica crystallites in the presence of gadolinium oxide. They were highlighted by SEM micrographs.

Coroiu, I., E-mail: coroiu@phys.utcluj.ro; Pascuta, P., E-mail: coroiu@phys.utcluj.ro; Bosca, M., E-mail: coroiu@phys.utcluj.ro; Culea, E., E-mail: coroiu@phys.utcluj.ro [Technical University, Chemical and Physics Department, 28, Memorandumului, 400114, Cluj-Napoca (Romania)

2013-11-13T23:59:59.000Z

173

The LHCb RICH silica aerogel performance with LHC data  

E-Print Network [OSTI]

In the LHCb detector at the Large Hadron Collider, powerful charged particle identification is performed by Ring Imaging Cherenkov (RICH) technology. In order to cover the full geometric acceptance and the wide momentum range (1-100 GeV/c), two detectors with three Cherenkov radiators have been designed and installed. In the medium (10-40 GeV/c) and high (30-100 GeV/c) momentum range, gas radiators are used (C4F10 and CF4 respectively). In the low momentum range (1 to a few GeV/c) pion/kaon/proton separation will be done with photons produced in solid silica aerogel. A set of 16 tiles, with the large transverse dimensions ever (20x20 cm$^2$) and nominal refractive index 1.03 have been produced. The tiles have excellent optical properties and homogeneity of refractive index within the tile of ~1%. The first data collected at LHC are used to understand the behaviour of the RICH: preliminary results will be presented and discussed on the performance of silica aerogel and of the gas radiators C4F10 and CF4.

Perego, D L

2010-01-01T23:59:59.000Z

174

Synthesis and properties of Chitosan-silica hybrid aerogels  

SciTech Connect (OSTI)

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.

Ayers, Michael R.; Hunt, Arlon J.

2001-06-01T23:59:59.000Z

175

Macroscopic Subdivision of Silica Aerogel Collectors for Sample Return Missions  

SciTech Connect (OSTI)

Silica aerogel collector tiles have been employed for the collection of particles in low Earth orbit and, more recently, for the capture of cometary particles by NASA's Stardust mission. Reliable, reproducible methods for cutting these and future collector tiles from sample return missions are necessary to maximize the science output from the extremely valuable embedded particles. We present a means of macroscopic subdivision of collector tiles by generating large-scale cuts over several centimeters in silica aerogel with almost no material loss. The cut surfaces are smooth and optically clear allowing visual location of particles for analysis and extraction. This capability is complementary to the smaller-scale cutting capabilities previously described [Westphal (2004), Ishii (2005a, 2005b)] for removing individual impacts and particulate debris in tiny aerogel extractions. Macroscopic cuts enable division and storage or distribution of portions of aerogel tiles for immediate analysis of samples by certain techniques in situ or further extraction of samples suited for other methods of analysis.

Ishii, H A; Bradley, J P

2005-09-14T23:59:59.000Z

176

Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky*  

E-Print Network [OSTI]

Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Vapors Jiangquan time-domain spectroscopy (THz-TDS) study of hydrophobic and hydrophilic silica aerogels, and the adsorption of several molecular vapors in the hydrophilic silica aerogel. The hydrophobic and hydrophilic

177

THE JOURNAL OF CHEMICAL PHYSICS 140, 224502 (2014) Search for a liquid-liquid critical point in models of silica  

E-Print Network [OSTI]

from pure sil- ica are widely used by the telecommunications industry and, because silica and silicates in models of silica Erik Lascaris,1 Mahin Hemmati,2 Sergey V. Buldyrev,3 H. Eugene Stanley,1 and C. Austen indicated the possible existence of a liquid-liquid critical point (LLCP) in models of silica at high

Stanley, H. Eugene

178

Research papers Polymerization of aqueous silica in H2OK2O solutions at 25200 C and 1 bar  

E-Print Network [OSTI]

Research papers Polymerization of aqueous silica in H2O­K2O solutions at 25­200 °C and 1 bar to 20 Aqueous silica polymerization Diamond anvil cell Alkaline uids Ab initio calculation Understanding the polymerization of aqueous silica is important for modeling uid­rock interactions at high pressure and temperature

Manning, Craig

179

Aluminum and silica intake in drinking water and the risk of Alzheimer's disease or cognitive decline: findings of the  

E-Print Network [OSTI]

Aluminum and silica intake in drinking water and the risk of Alzheimer's disease or cognitive,2 , Commenges Daniel1,2 , Helmer Catherine2,3 , Jean-François Dartigues2,3 . Abbreviations: Al, Aluminum; AD, Alzheimer's Disease; MMSE, Mini Mental State Examination; Si, Silica Running head: Aluminum, silica in water

Paris-Sud XI, Université de

180

Apoptosis induction by silica nanoparticles mediated through reactive oxygen species in human liver cell line HepG2  

SciTech Connect (OSTI)

Silica nanoparticles are increasingly utilized in various applications including agriculture and medicine. In vivo studies have shown that liver is one of the primary target organ of silica nanoparticles. However, possible mechanisms of hepatotoxicity caused by silica nanoparticles still remain unclear. In this study, we explored the reactive oxygen species (ROS) mediated apoptosis induced by well-characterized 14 nm silica nanoparticles in human liver cell line HepG2. Silica nanoparticles (25–200 ?g/ml) induced a dose-dependent cytotoxicity in HepG2 cells. Silica nanoparticles were also found to induce oxidative stress in dose-dependent manner indicated by induction of ROS and lipid peroxidation and depletion of glutathione (GSH). Quantitative real-time PCR and immunoblotting results showed that both the mRNA and protein expressions of cell cycle checkpoint gene p53 and apoptotic genes (bax and caspase-3) were up-regulated while the anti-apoptotic gene bcl-2 was down-regulated in silica nanoparticles treated cells. Moreover, co-treatment of ROS scavenger vitamin C significantly attenuated the modulation of apoptotic markers along with the preservation of cell viability caused by silica nanoparticles. Our data demonstrated that silica nanoparticles induced apoptosis in human liver cells, which is ROS mediated and regulated through p53, bax/bcl-2 and caspase pathways. This study suggests that toxicity mechanisms of silica nanoparticles should be further investigated at in vivo level. -- Highlights: ? We explored the mechanisms of toxicity caused by silica NPs in human liver HepG2 cells. ? Silica NPs induced a dose-dependent cytotoxicity in HepG2 cells. ? Silica NPs induced ROS generation and oxidative stress in a dose-dependent manner. ? Silica NPs were also modulated apoptosis markers both at mRNA and protein levels. ? ROS mediated apoptosis induced by silica NPs was preserved by vitamin C.

Ahmad, Javed [Department of Zoology, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)] [Department of Zoology, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Ahamed, Maqusood, E-mail: maqusood@gmail.com [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia)] [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Akhtar, Mohd Javed [Fibre Toxicology, CSIR-Indian Institute of Toxicology Research, Lucknow-226001 (India)] [Fibre Toxicology, CSIR-Indian Institute of Toxicology Research, Lucknow-226001 (India); Alrokayan, Salman A. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia)] [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Siddiqui, Maqsood A.; Musarrat, Javed; Al-Khedhairy, Abdulaziz A. [Department of Zoology, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)] [Department of Zoology, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)

2012-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

INFLUENCE OF PHENYLTRIMETHOXYSILANE ON PHYSICOCHEMICAL PROPERTIES OF TEOS BASED MONOLITHIC SILICA AEROGELS PREPARED BY SUPERCRITICAL DRYING PROCESS  

E-Print Network [OSTI]

The objective of the present research work is to synthesize transparent, hydrophobic, monolithic silica aerogels with ultralow density by using supercritical drying process. The effect of phenyltrimethoxysilane as a hydrophobic reagent on the physicochemical properties of the silica aerogels has been studied. The total processing time for the synthesis of monolithic silica aerogels minimized to 29 h which was ~2 days. We have succeeded to get ultralow density of the silica aerogels as low as 24 Kgm-3 with 165 ° water droplet contact angle. The ultralow density affects the thermal conductivity of the silica aerogels.

Kavale Mahendra S; Mahadik D. B; Parale V. G; Mane P. B; Vhatkar R. S; A. Venkateswara Rao; Wagh P. B; Satish C. Gupta

182

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

SciTech Connect (OSTI)

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.

Saw, Jimmy H [Los Alamos National Laboratory; Mountain, Bruce W [NEW ZEALAND; Feng, Lu [NANKAI UNIV; Omelchenko, Marina V [NCBI/NLM/NIH; Hou, Shaobin [UNIV OF HAWAII; Saito, Jennifer A [UNIV OF HAWAII; Stott, Matthew B [NEW ZEALAND; Li, Dan [NANKAI UNIV; Zhao, Guang [NANKAI UNIV; Wu, Junli [NANKAI UNIV; Galperin, Michael Y [NCBI/NLM/NIH; Koonin, Eugene V [NCBI/NLM/NIH; Makarova, Kira S [NCBI/NLM/NIH; Wolf, Yuri I [NCBI/NLM/NIH; Rigden, Daniel J [UNIV OF LIVERPOOL; Dunfield, Peter F [UNIV OF CALGARY; Wang, Lei [NANKAI UNIV; Alam, Maqsudul [UNIV OF HAWAII

2008-01-01T23:59:59.000Z

183

Hydrogen and oxygen adsorption stoichiometries on silica supported ruthenium nanoparticles  

SciTech Connect (OSTI)

Treatment under H{sub 2} at 300 C of Ru(COD)(COT) dispersed on silica yields 2 nm ruthenium nanoparticles, [Ru{sub p}/SiO{sub 2}], according to EXAFS, HRTEM and XPS. H{sub 2} adsorption measurements on [Ru{sub p}/SiO{sub 2}] in the absence of O{sub 2} show that Ru particles adsorb up to ca. 2 H per surface ruthenium atoms (2H/Ru{sub s}) on various samples; this technique can therefore be used to measure the dispersion of Ru particles. In contrast, O{sub 2} adsorption on [Ru{sub p}/SiO{sub 2}] leads to a partial oxidation of the bulk at 25 C, to RuO{sub 2} at 200 C and to sintering upon further reduction under H{sub 2}, showing that O{sub 2} adsorption cannot be used to measure the dispersion of Ru particles.

Berthoud, Romain; Delichere, Pierre; Gajan, David; Lukens, Wayne; Pelzer, Katrin; Basset, Jean-Marie; Candy, Jean-Pierre; Coperet, Christophe

2008-12-01T23:59:59.000Z

184

Mechanical Loss in Tantala/Silica Dielectric Mirror Coatings  

E-Print Network [OSTI]

Current interferometric gravitational wave detectors use test masses with mirror coatings formed from multiple layers of dielectric materials, most commonly alternating layers of SiO2 (silica) and Ta2O5 (tantala). However, mechanical loss in the Ta2O5/SiO2 coatings may limit the design sensitivity for advanced detectors. We have investigated sources of mechanical loss in the Ta2O5/SiO2 coatings, including loss associated with the coating-substrate interface, with the coating-layer interfaces, and with the bulk material. Our results indicate that the loss is associated with the bulk coating materials and that the loss of Ta2O5 is substantially larger than that of SiO2.

Steven D. Penn; Peter H. Sneddon; Helena Armandula; Joseph C. Betzwieser; Gianpietro Cagnoli; Jordan Camp; D. R. M. Crooks; Martin M. Fejer; Andri M. Gretarsson; Gregory M. Harry; Jim Hough; Scott E. Kittelberger; Michael J. Mortonson; Roger Route; Sheila Rowan; Christophoros C. Vassiliou

2003-02-24T23:59:59.000Z

185

Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports  

SciTech Connect (OSTI)

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.

Keith James Stanger

2003-05-31T23:59:59.000Z

186

Synthesis and characterization of barium ferrite–silica nanocomposites  

SciTech Connect (OSTI)

In this work, we prepared barium ferrite-silica (BaM-SiO{sub 2}) nanocomposites of different molar ratios by high-energy ball milling, followed by heat-treatment at different temperatures. The microstructure, morphology and magnetic properties were characterized for different synthesis conditions by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results indicate that 15 h of milling was enough to avoid the generation of hematite phase and to get a good dispersion of barium ferrite particles in the ceramic matrix. For milling periods beyond 15 h and heat treatment above 900 °C, the XRD patterns showed the presence of hematite phase caused by the decomposition of BaM. The agglomerate size observed through SEM analysis was around 150 nm with a good BaM dispersion into the SiO{sub 2} matrix. The highest saturation magnetization (Ms) value obtained was 43 emu/g and the corresponding coercivity (Hc) value of 3.4 kOe for the composition 60BaM-40SiO{sub 2} milled for 15 h and heat treated at 900 °C. This coercivity value is acceptable for the application in magnetic recording media. Highlights: • Barium ferrite–silica nanocomposites were prepared by high energy ball milling. • Optimal processing time is 15 h milling and heat treatment at 900 °C. • This is enough to avoid the generation of hematite phase. • Obtain good dispersion of barium ferrite particles in the ceramic matrix • Above this processing time shows the presence of increased amount of hematite.

Aguilar-González, M.A.; Mendoza-Suárez, G.; Padmasree, K.P., E-mail: padma512@yahoo.com

2013-10-15T23:59:59.000Z

187

KrF- and ArF-excimer-laser-induced absorption in silica glasses produced by melting synthetic silica powder  

SciTech Connect (OSTI)

KrF- and ArF-excimer-laser-induced absorption of silica glasses produced by electric melting and flame fusion of synthetic silica powder were investigated. The growth of KrF-laser-induced absorption was more gradual than that of ArF-laser-induced absorption. Induced absorption spectra exhibited a peak at about 5.8 eV, of which the position and width differed slightly among samples and laser species. Widths of ArF-laser-induced absorption spectra were wider than those of KrF-laser-induced spectra. KrF-laser-induced absorption is reproducible by two Gaussian absorption bands peaking at 5.80 eV with full width at half maximum (FWHM) of 0.62 eV and at 6.50 eV with FWHM of 0.74 eV. For reproduction of ArF-laser-induced absorption, Gaussian bands at 5.41 eV with FWHM of 0.62 eV was necessary in addition to components used for reproducing KrF-laser-induced absorption. Based on the discussion of the change of defect structures evaluated from change of absorption components, we proposed that the precursor of the 5.8-eV band ascribed to E Prime center ({identical_to}Si{center_dot}) is {identical_to}Si-H HO-Si{identical_to} structures formed by the reaction between strained Si-O-Si bonds and interstitial H{sub 2} molecules during the irradiation.

Kuzuu, Nobu; Sasaki, Toshiya; Kojima, Tatsuya [Department of Applied Physics, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507 (Japan); Tanaka, Jun-ichiro; Nakamura, Takayuki; Horikoshi, Hideharu [Tosoh SGM Corp., 4555 Kaisei-cho, Shunan-shi, Yamaguchi 746-0006 (Japan)

2013-07-07T23:59:59.000Z

188

Ammoniated silica-alumina gel and catalyst containing the same and processes for producing same  

SciTech Connect (OSTI)

This invention relates to hydrothermally treated silica-alumina cogels resulting in a reduction in the NH/sub 4/ content of the gel and the employment of such gels as cracking catalysts.

Alafandi, H.; Stamires, D.

1980-12-09T23:59:59.000Z

189

E-Print Network 3.0 - aluminate-silica fume mixtures Sample Search...  

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

< 1 2 3 4 5 > >> Page: << < 1 2 3 4 5 > >> 21 Carbon 39 (2001) 19952001 Silane-treated carbon fiber for reinforcing cement Summary: -treated carbon fibers and silane-treated silica...

190

E-Print Network 3.0 - aperture fused silica Sample Search Results  

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

using a Kaufman type ion source to figure 8 cm diameter fused silica and silicon carbide samples... cases are shown in Table 1 and Figure 1. Using a 3 cm diameter Ion Tech...

191

ORNL devises recipe to fine-tune diameter of silica rods | ornl...  

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

the stage for advances in anti-reflective solar cells, computer monitors, TV screens, eye glasses and more. The goal of fabricating fixed-size one-dimensional silica structures...

192

Method for inhibiting silica precipitation and scaling in geothermal flow systems  

DOE Patents [OSTI]

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.

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

1980-06-13T23:59:59.000Z

193

Fundamental Studies on Polymer and Organic-Inorganic Hybrid Nanoparticles Reinforced Silica Aerogels.  

E-Print Network [OSTI]

??The objective of this research was to reinforce silica aerogels using functional organic-inorganic hybrid nanoparticles, silane end-capped polyurethane oligomer and chain extended polymer, and self-crosslinkable… (more)

Duan, Yannan

2012-01-01T23:59:59.000Z

194

Study of the Behavior of a Commercial Scale Inhibitor on Silica Sand  

E-Print Network [OSTI]

squeeze lifetimes in order to minimize the number of treatments, thus reducing the cost. The objective of this thesis is to study the adsorption of the commercial scale inhibitor SI onto silica sand. By investigating this intrinsic phenomenon, an optimized...

Vaca Bustamante, Victor

2010-12-14T23:59:59.000Z

195

E-Print Network 3.0 - abundant circumstellar silica Sample Search...  

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

67 doi:10.1016S0016-7037(03)00461-7 Pristine presolar silicon carbide Summary: silica coatings of as much as several tens of nm thickness, perhaps due to oxidation of the Si......

196

E-Print Network 3.0 - alcali-silica reactions mechanisms Sample...  

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

results for: alcali-silica reactions mechanisms Page: << < 1 2 3 4 5 > >> 1 GTQ, Chemistry 212, Dr. Glaser, FS96 --1 --GTQ on Baeyer-Villiger Reaction. (20 points,...

197

Laser-induced fluorescence of fused silica irradiated by ArF excimer laser  

SciTech Connect (OSTI)

Laser-induced fluorescence (LIF) of high-purity fused silica irradiated by ArF excimer laser is studied experimentally. LIF bands of the fused silica centered at 281 nm, 478 nm, and 650 nm are observed simultaneously. Furthermore, the angular distribution of the three fluorescence peaks is examined. Microscopic image of the laser modified fused silica indicates that scattering of the generated fluorescence by laser-induced damage sites is the main reason for the angular distribution of LIF signals. Finally, the dependence of LIF signals intensities of the fused silica on laser power densities is presented. LIF signals show a squared power density dependence, which indicates that laser-induced defects are formed mainly via two-photon absorption processes.

Zhang Haibo [Shanghai Key Laboratory of All Solid-state Laser and Applied Techniques, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China); Graduate University of Chinese Academy of Science, Beijing 100049 (China); Yuan Zhijun; Zhou Jun; Dong Jingxing; Wei Yunrong; Lou Qihong [Shanghai Key Laboratory of All Solid-state Laser and Applied Techniques, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China)

2011-07-01T23:59:59.000Z

198

Method for inhibiting silica precipitation and scaling in geothermal flow systems  

DOE Patents [OSTI]

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.

Harrar, Jackson E. (Castro Valley, CA); Lorensen, Lyman E. (Orinda, CA); Locke, Frank E. (Lafayette, CA)

1982-01-01T23:59:59.000Z

199

E-Print Network 3.0 - ash-silica fume pastes Sample Search Results  

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

; Engineering 100 By-Products Utilization Summary: of Recycled Aggregates in Self-Compacting4 Concrete", Fly Ash, Silica Fume, Slag and Natural Pozzolans... (0.00028 in.). For...

200

Treatment of domestic wastewater for reuse with activated silica and magnesia  

E-Print Network [OSTI]

which are of concern in treat- ment for potable purposes are organics and trace inorganics. This research project was conducted in an attempt to determine if organic oxides such as activated silica and magnesia in various combinations with alum... in Wastewater Toxic Inorganics in Wastewater Existing Technology Coagulation and Flocculation Lime Coagulation . . ~ Alum Coagulation . ~ ~ ~ ~ Activated Silica Magnesia 5 6 8 9 10 13 14 15 16 III EXPERIMENTAL PLAN Was tewater ~ ~ ~ ~ ~ Jar...

Lindner, John Howard

1985-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

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

SciTech Connect (OSTI)

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.

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)

1997-04-01T23:59:59.000Z

202

Synthesis of Novel Polypeptide-Silica Hybrid Materials through Surface-Initiated N-carboxyanhydride Polymerization  

E-Print Network [OSTI]

synthesis routes derived from sol-gel chemistry .......................... 4 1.3 Polymerization behavior of aqueous silica ............................................................ 11 1.4 Simulated structures from various growth models... are still used; however, the use of sol-gel chemistry for silica matrix construction permits the greatest degree of design flexibility and variety of materials that can be synthesized. Common synthesis techniques derived from sol-gel chemistry have been...

Lunn, Jonathan D.

2011-08-08T23:59:59.000Z

203

The effect of lattice temperature on surface damage in fused silica optics  

SciTech Connect (OSTI)

We examine the effect of lattice temperature on the probability of surface damage initiation for 355nm, 7ns laser pulses for surface temperatures below the melting point to temperatures well above the melting point of fused silica. At sufficiently high surface temperatures, damage thresholds are dramatically reduced. Our results indicate a temperature activated absorption and support the idea of a lattice temperature threshold of surface damage. From these measurements, we estimate the temperature dependent absorption coefficient for intrinsic silica.

Bude, J; Guss, G; Matthews, M; Spaeth, M L

2007-10-31T23:59:59.000Z

204

Silica and acid-detergent fiber content of five varieties of bermudagrass  

E-Print Network [OSTI]

SILICA &ID ACID-DETERGENT FIBER CONTENT OF FIVE VARIETIES OF BERMUDAGRASS A Thesis by FREDERICK MICHAEL JUNGMAN Submitted to the Graduate College of Texas A&M Uniuersity in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1971 Major Subject: Agronomy SILICA AND ACID-DETERGENT FIBER CONTENT 01' FIVE VARIETIES OF BEI~DAGRASS A Thesis by FREDERICK MICHAEL OUNGMAN Approved as to style and content by: (Chai rman of Coamd t tee) (llead of. Department...

Jungman, Frederick Michael

1971-01-01T23:59:59.000Z

205

Templated Control of Au nanospheres in Silica Nanowires  

SciTech Connect (OSTI)

The formation of regularly-spaced metal nanostructures in selectively-placed insulating nanowires is an important step toward realization of a wide range of nano-scale electronic and opto-electronic devices. Here we report templated synthesis of Au nanospheres embedded in silica nanowires, with nanospheres consistently spaced with a period equal to three times their diameter. Under appropriate conditions, nanowires form exclusively on Si nanostructures because of enhanced local oxidation and reduced melting temperatures relative to templates with larger dimensions. We explain the spacing of the nanospheres with a general model based on a vapor-liquid-solid mechanism, in which an Au/Si alloy dendrite remains liquid in the nanotube until a critical Si concentration is achieved locally by silicon oxide-generated nanowire growth. Additional Si oxidation then locally reduces the surface energy of the Au-rich alloy by creating a new surface with minimum area inside of the nanotube. The isolated liquid domain subsequently evolves to become an Au nanosphere, and the process is repeated.

Tringe, J W; Vanamu, G; Zaidi, S H

2007-03-15T23:59:59.000Z

206

Implantation conditions for diamond nanocrystal formation in amorphous silica  

SciTech Connect (OSTI)

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.

Buljan, Maja; Radovic, Iva Bogdanovic; Desnica, Uros V.; Ivanda, Mile; Jaksic, Milko [Ruder Boskovic Institute, P.O. Box 180, 10002 Zagreb (Croatia); Saguy, Cecile; Kalish, Rafi [Physics Department and Solid State Institute, Technion, Haifa 32000 (Israel); Djerdj, Igor [Department of Materials, Swiss Federal Institute of Technology (ETH) Zuerich, Wolfgang-Pauli-Str. 10, CH-8093 Zuerich (Switzerland); Tonejc, Andelka [Faculty of Science, Department of Physics, University of Zagreb, 10000 Zagreb (Croatia); Gamulin, Ozren [School of Medicine, Zagreb University, 10000 Zagreb (Croatia)

2008-08-01T23:59:59.000Z

207

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

SciTech Connect (OSTI)

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.

Figus, Cristiana, E-mail: cristiana.figus@dsf.unica.it; Quochi, Francesco, E-mail: cristiana.figus@dsf.unica.it; Artizzu, Flavia, E-mail: cristiana.figus@dsf.unica.it; Saba, Michele, E-mail: cristiana.figus@dsf.unica.it; Marongiu, Daniela, E-mail: cristiana.figus@dsf.unica.it; Mura, Andrea; Bongiovanni, Giovanni [Dipartimento di Fisica - University of Cagliari, S.P. Km 0.7, I-09042 Monserrato (Canada) (Italy); Floris, Francesco; Marabelli, Franco; Patrini, Maddalena; Fornasari, Lucia [Dipartimento di Fisica - University of Pavia, Via Agostino Bassi 6, I-27100 Pavia (PV) (Italy); Pellacani, Paola; Valsesia, Andrea [Plasmore S.r.l. -Via Grazia Deledda 4, I-21020 Ranco (Vatican City State, Holy See) (Italy)

2014-10-21T23:59:59.000Z

208

NiO-silica based nanostructured materials obtained by microemulsion assisted sol-gel procedure  

SciTech Connect (OSTI)

Graphical abstract: TEM micrograph of NiO/SiO{sub 2} nanoparticles. Highlights: {yields} Microemulsion assisted sol-gel procedure for NiO silica nanomaterials synthesis. {yields} Controlling the size and shape of nanoparticles and avoiding their aggregation. {yields} Narrow band-gap semiconductors (energies <3 eV) absorbing VIS or near-UV light biologically and chemically inert semiconductors entrapping/coating in silica network. {yields} Low cost as the microemulsion is firstly used in water metallic cation extraction. -- Abstract: NiO-silica based materials have been synthesized by microemulsion assisted sol-gel procedure. The versatility of these soft nanotechnology techniques has been exploited in order to obtain different types of nanostructures, such as NiO nanoparticles, NiO silica coated nanoparticles and NiO embedded in silica matrix. These materials have been characterized by adequate structural and morphology techniques: DLS, HR-TEM/SAED, BET, AFM. Optical and semiconducting properties (band-gap values) of the synthesized materials have been quantified by means of VIS-NIR diffuse reflectance spectra, thus demonstrating their applicative potential in various electron transfer phenomena such as photocatalysis, electrochromic thin films, solid oxide fuel cells.

Mihaly, M.; Comanescu, A.F. [University POLITEHNICA Bucharest, Faculty of Applied Chemistry and Materials Science, 1 Polizu, 011061 Bucharest (Romania)] [University POLITEHNICA Bucharest, Faculty of Applied Chemistry and Materials Science, 1 Polizu, 011061 Bucharest (Romania); Rogozea, A.E. [ILIE MURGULESCU Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania)] [ILIE MURGULESCU Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Vasile, E. [METAV Research and Development, 31 C.A. Rosetti, 020011 Bucharest (Romania)] [METAV Research and Development, 31 C.A. Rosetti, 020011 Bucharest (Romania); Meghea, A., E-mail: a.meghea@gmail.com [University POLITEHNICA Bucharest, Faculty of Applied Chemistry and Materials Science, 1 Polizu, 011061 Bucharest (Romania)

2011-10-15T23:59:59.000Z

209

Direct encapsulation of water-soluble drug into silica microcapsules for sustained release applications  

SciTech Connect (OSTI)

Direct encapsulation of water-soluble drug into silica microcapsules was facilely achieved by a sol-gel process of tetraethoxysilane (TEOS) in W/O emulsion with hydrochloric acid (HCl) aqueous solution containing Tween 80 and drug as well as cyclohexane solution containing Span 80. Two water-soluble drugs of gentamicin sulphate (GS) and salbutamol sulphate (SS) were chosen as model drugs. The characterization of drug encapsulated silica microcapsules by scanning electronic microscopy (SEM), FTIR, thermogravimetry (TG) and N{sub 2} adsorption-desorption analyses indicated that drug was successfully entrapped into silica microcapsules. The as-prepared silica microcapsules were uniform spherical particles with hollow structure, good dispersion and a size of 5-10 {mu}m, and had a specific surface area of about 306 m{sup 2}/g. UV-vis and thermogravimetry (TG) analyses were performed to determine the amount of drug encapsulated in the microcapsules. The BJH pore size distribution (PSD) of silica microcapsules before and after removing drug was examined. In vitro release behavior of drug in simulated body fluid (SBF) revealed that such system exhibited excellent sustained release properties.

Wang Jiexin; Wang Zhihui [Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Chen Jianfeng [Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China)], E-mail: chenjf@mail.buct.edu.cn; Yun, Jimmy [Nanomaterials Technology Pte. Ltd., 28 Ayer Rajah Crescent 03-03, Singapore 139959 (Singapore)

2008-12-01T23:59:59.000Z

210

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

DOE Patents [OSTI]

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.

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

2006-05-02T23:59:59.000Z

211

Preparation and sintering of silica-doped zirconia by colloidal processing  

SciTech Connect (OSTI)

Silica-doped (SiO{sub 2} = 0--1.0 mass%) zirconia (3 mol% Y{sub 2}O{sub 3}-doped tetragonal ZrO{sub 2}) compacts are prepared from hetero-coagulated and well-dispersed suspensions by colloidal processing. The suspensions are consolidated by a pressure filtration technique. The green density of the compacts consolidated from the well-dispersed suspensions is higher than that from the hetero-coagulated suspensions. The lower density of the latter compacts is improved by a subsequent cold isostatic pressing (CIP) at 400 MPa. The sinterability of the compacts at 1,200 C is greatly affected by the amount of doped silica. The densification and grain growth are hindered by silica doping above 0.3 wt% at 1,200 C. All the compacts are densificated to a relative density of above 99% by sintering at 1,300 C for 2 h.

Uchikoshi, T.; Sakka, Y.; Ozawa, K.; Hiraga, K. [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)

1997-09-01T23:59:59.000Z

212

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

SciTech Connect (OSTI)

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

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

2007-01-24T23:59:59.000Z

213

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

SciTech Connect (OSTI)

Small angle neutron scattering (SANS) has been carried out to study the interaction of anionic silica nanoparticles (88 Å) 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 (0–5 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.

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)

2014-04-24T23:59:59.000Z

214

ADVANCES IN HYDROGEOCHEMICAL INDICATORS FOR THE DISCOVERY OF NEW GEOTHERMAL RESOURCES IN THE GREAT BASIN, USA  

SciTech Connect (OSTI)

This report summarizes the results of Phase I work for a go/no go decision on Phase II funding. In the first objective, we assessed the extent to which fluid-mineral equilibria controlled deep water compositions in geothermal systems across the Great Basin. Six systems were evaluated: Beowawe; Desert Peak; Dixie Valley; Mammoth; Raft River; Roosevelt. These represent a geographic spread of geothermal resources, in different geological settings and with a wide range of fluid compositions. The results were used for calibration/reformulation of chemical geothermometers that reflect the reservoir temperatures in producing reservoirs. In the second objective, we developed a reactive -transport model of the Desert Peak hydrothermal system to evaluate the processes that affect reservoir fluid geochemistry and its effect on solute geothermometry. This included testing geothermometry on “reacted” thermal water originating from different lithologies and from near-surface locations where the temperature is known from the simulation. The integrated multi-component geothermometer (GeoT, relying on computed mineral saturation indices) was tested against the model results and also on the systems studied in the first objective.

Simmons, Stuart F [Colorado School of Mines; Spycher, Nicolas [Lawrence Berkeley National Laboratory; Sonnenthal, Eric [Lawrence Berkeley National Laboratory; Dobson, Patrick [Lawrence Berkeley National Laboratory

2013-05-20T23:59:59.000Z

215

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

SciTech Connect (OSTI)

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.

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

1990-08-01T23:59:59.000Z

216

Development of 3-D magnetic nano-arrays by electrodeposition into mesoporous silica.  

SciTech Connect (OSTI)

The development of periodic nanostructures fabricated by self-assembly of surfactants and block co-polymers has opened up the possibility of generating periodic magnetic nanostructures of types not accessible by self-assembly of nano-particles. The fabrication of mesoporous silica thin films around self-assembled block co-polymers is well established. Common structures for such films are SBA-15 which consists of hexagonal arrays of cylindrical pores and SBA-16 which has face centered arrays of spherical voids. These pores are connected by 1-2 nm thick flaws in the continuous silica phase producing an effectively continuous porous phase. After removal of the block co-polymer template, electrodeposition into the mesoporous silica thin films produces arrays of 5-10 nm diameter nano-wires and nano-particles. We have demonstrated that such materials can be fabricated on a wide range of metal substrates. Characterization by Scanning Electron Microscopies shows that the mesoporous silica is well ordered over micron scale areas. Grazing Incidence Small Angle X-ray Scattering (GISAXS) studies shows diffraction spots, consistent with the entire film being well ordered. GISAXS also shows that the mesoporous silica films survive removal of the template and electrodeposition of nickel and cobalt into the mesoporous silica films. Such films are of interest for their magnetic properties, as the nanophase and scale can be independently varied. Further, the presence of nanowires inside an insulator suggests that these films might also be of interest as the current confining element for Confined Current Path-Current Perpendicular to Plane GMR sensors.

Campbell, R.; Manning, J.; Bakker, M.G.; Li, X.; Lee, D.R.; Wang, J.; X-Ray Science Division; Univ. of Alabama

2006-01-01T23:59:59.000Z

217

Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy and ultra-small angle  

E-Print Network [OSTI]

Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy of silica aerogels has been extensively studied mainly by scattering techniques (neutrons, X-rays, light) and atomic force microscopy (AFM) experiments have been carried out on aerogels at dierent steps of densi

Demouchy, Sylvie

218

Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports  

E-Print Network [OSTI]

Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports Guillaume 420, 650-653 (2002). 7. C. M. Smith et al., "Low-loss hollow-core silica/air photonic bandgap fibre yong@its.caltech.edu. Abstract: We demonstrate a new class of hollow-core Bragg fibers

Huang, Yanyi

219

Am J Epidemiol . Author manuscript Aluminum and silica in drinking water and the risk of Alzheimers disease'  

E-Print Network [OSTI]

Am J Epidemiol . Author manuscript Page /1 10 Aluminum and silica in drinking water and the risk associations between exposure to aluminum or silica from drinking water and risk of cognitive decline, dementia of dementia, aged' 65 years and over living in 91 civil drinking water areas in Southern France. Two measures

Paris-Sud XI, Université de

220

Structure and Dynamics of Acetonitrile Confined in a Silica Nanopore Liwen Cheng, Joseph A. Morrone, and B. J. Berne*  

E-Print Network [OSTI]

Structure and Dynamics of Acetonitrile Confined in a Silica Nanopore Liwen Cheng, Joseph A. Morrone York 10027, United States ABSTRACT: Acetonitrile confined in silica nanopores with surfaces of varying. It is found that acetonitrile orders into bilayer like structures near the surface, in agreement with prior

Berne, Bruce J.

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Water, chloroform, acetonitrile, and atrazine adsorption to the amorphous silica surface studied by vibrational sum frequency generation spectroscopy  

E-Print Network [OSTI]

Water, chloroform, acetonitrile, and atrazine adsorption to the amorphous silica surface studied the air­silica interface before, during, and after adsorption of water, chloroform, acetonitrile the compounds. Adsorption of chloro- form and acetonitrile was weaker compared to water. Binding to the surface

222

IMPROVING SILICA FUME FOR CONCRETE BY SURFACE TREATMENT X. Li and D.D.L. Chung1  

E-Print Network [OSTI]

(Type I) from Lafarge Corp. (Southfield, MI). The silica fume (Elkem Materials, Inc., Pittsburgh, PA, EMS 965) was used in the amount of 15% by weight of cement. Surface treatment of silica fume Printed in the USA. All rights reserved 0008-8846/98 $19.00 .00 PII S0008-8846(98)00017-9 493 #12;effect

Chung, Deborah D.L.

223

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

SciTech Connect (OSTI)

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.

Hunt, Jonathan

2013-01-31T23:59:59.000Z

224

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

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

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.

Hunt, Jonathan

225

Preparation of Mesoporous Silica Templated Metal Nanowire Films on Foamed Nickel Substrates  

SciTech Connect (OSTI)

A method has been developed for the formation of high surface area nanowire films on planar and three-dimensional metal electrodes. These nanowire films are formed via electrodeposition into a mesoporous silica film. The mesoporous silica films are formed by a sol-gel process using Pluronic tri-block copolymers to template mesopore formation on both planar and three-dimensional metal electrodes. Surface area increases of up to 120-fold have been observed in electrodes containing a templated film when compared to the same types of electrodes without the templated film.

Campbell, Roger [University of Alabama, Tuscaloosa; Kenik, Edward A [ORNL; Bakker, Martin [University of Alabama, Tuscaloosa; Havrilla, George [Los Alamos National Laboratory (LANL); Montoya, Velma [Los Alamos National Laboratory (LANL); Shamsuzzoha, Mohammed [University of Alabama, Tuscaloosa

2006-01-01T23:59:59.000Z

226

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

DOE Patents [OSTI]

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.

Heung, Leung K. (Aiken, SC)

1999-01-01T23:59:59.000Z

227

Decomposition of cumyl hydroperoxide in the presence of sulphonated silica in a flow-type system  

SciTech Connect (OSTI)

An investigation has been made of the decomposition of cumyl hydroperoxide (CHP) in the presence of silica-based sulphocationites in a flow-type system. It was established that the given specimens are effective catalysts for the decomposition of CHP into phenol and acetone. It was shown that, in the course of the process, no irreversible poisoning of the surface of the catalyst by the products of CHP decomposition occurs. Data of chromatographic analysis of the products of CHP decomposition in the presence of sulphuric acid and silica-based sulphocationites are given.

Shelpakova, N.A.; Ioffa, A.F.

1993-12-31T23:59:59.000Z

228

Bulk and surface laser damage of silica by picosecond and nanosecond pulses at 1064 nm  

SciTech Connect (OSTI)

We measured bulk and surface dielectric breakdown thresholds of pure silica for 14 ps and 8 ns pulses of 1064 nm light. The thresholds are sharp and reproducible. For the 8 ns pulses the bulk threshold irradiance is 4.75 {+-} 0.25 kW/{mu}m{sup 2}. The threshold is approximately three times higher for 14 ps pulses. For 8 ns pulses the input surface damage threshold can be made equal to the bulk threshold by applying an alumina or silica surface polish.

Smith, Arlee V.; Do, Binh T

2008-09-10T23:59:59.000Z

229

Electron-Irradiation Induced Nanocrystallization of Pb(II) in Silica Gels Prepared in High Magnetic Field  

E-Print Network [OSTI]

In a previous study, structure of silica gels prepared in a high magnetic field was investigated. While a direct application of such anisotropic silica gels is for an optical anisotropic medium possessing chemical resistance, we show here their possibility of medium in materials processing. In this direction, for example, silica hydrogels have so far been used as media of crystal growth. In this paper, as opposed to the soft-wet state, dried silica gels have been investigated. We have found that lead (II) nanocrystallites were formed induced by electron irradiation to lead (II)-doped dried silica gels prepared in a high magnetic field such as B = 10 T. Hydrogels made from a sodium metasilicate solution doped with lead (II) acetate were prepared. The dried specimens were irradiated by electrons in a transmission electron microscope environment. Electron diffraction patterns indicated the crystallinity of lead (II) nanocrystallites depending on B. An advantage of this processing technique is that the crystallin...

Kaito, Takamasa; Kaito, Chihiro

2015-01-01T23:59:59.000Z

230

Effect of Carbon Black and Silica Fillers in Elastomer Blends Yimin Zhang, S. Ge, B. Tang, T. Koga, M. H. Rafailovich,*, J. C. Sokolov,  

E-Print Network [OSTI]

, the effect of carbon black is offset by silica fillers. Introduction Fillers exist in a variety of systemsEffect of Carbon Black and Silica Fillers in Elastomer Blends Yimin Zhang, S. Ge, B. Tang, T. Koga January 30, 2001 ABSTRACT: The effects of carbon black and pyrogeneous silica fillers on the interfacial

231

Ion irradiation damage in k-doped silica probed by the Er3+ luminescence lifetime at 1.535 pm4  

E-Print Network [OSTI]

irradiation.' Furthermore, silica-basedop- tical fibers are the standard in telecommunicationtechnol- ogy the effectof MeV ion irradiation damage on the optical propertiesof Er-doped silica films is studied. Erbium-doped silica glasshas recently attracted attention becauseof its use in optical fiber amplifiers.5'6Erbium

Polman, Albert

232

Heavy metal phosphate nanophases in silica: influence of radiolysis probed via f-electron state properties  

SciTech Connect (OSTI)

We have assessed the feasibility of carrying out time- and wavelength-resolved laser-induced fluorescence measurements of radiation damage in glassy silica. The consequences of alpha decay of Es-253 in LaPO{sub 4} nanophases embedded in silica were probed based on excitation of 5f states of Cm{sup 3+}, Bk{sup 3+}, and Es{sup 3+} ions. The recorded emission spectra and luminescence decays showed that alpha decay of Es-253 ejected Bk-249 decay daughter ions into the surrounding silica and created radiation damage within the LaPO{sub 4} nanophases. This conclusion is consistent with predictions of an ion transport code commonly used to model ion implantation. Luminescence from the {sup 6}D{sub 7/2} state of Cm{sup 3+}was used as an internal standard. Ion-ion energy transfer dominated the dynamics of the observed emitting 5f states and strongly influenced the intensity of observed spectra. In appropriate sample materials, laser-induced fluorescence provides a powerful method for fundamental investigation of alpha-induced radiation damage in silica.

Beitz, James V. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States)]. E-mail: beitz@anl.gov; Williams, C.W. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States); Hong, K.-S. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States); Liu, G.K. [Chemistry Division, 9700 South Cass Avenue, Argonne National Laboratory, Argonne, IL 60439-4831 (United States)

2005-02-15T23:59:59.000Z

233

Fluorescent silica colloids for study and visualization of skin care products  

E-Print Network [OSTI]

due to long exposures to cold and dry air (7). Different skin care products are used to hy- drate dryFluorescent silica colloids for study and visualization of skin care products Swaminathan Iyer: The efficacy of skin care products depends on the time and dynamics of their absorbance by the skin, and its

Sokolov, Igor

234

Effects of Surface Modification Conditions on Hydrophobicity of Silica-based Coating Additives  

SciTech Connect (OSTI)

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 improving water repellency and corrosion protection characteristics. The current generation of CARC topcoats is already highly loaded with solids, and thus there is a premium on minimization of the total SHS powder required to achieve the desired properties. Therefore, efficient surface modification of the silica and proper dispersion in the coating will be required. The effect of a dispersant on the surface modification of silica particles by chlorosilanes was addressed in this study. The properties of various SHS powders were characterized by thermogravimetric analysis and mass spectroscopy. Correlations between powder modification conditions and the ultimate effects of the modified particles on hydrophobicity of CARC topcoats were assessed. The use of contact and rolling angle measurements along with scanning electron microscopy are discussed as they pertain to the ability to quantify the effects of modified silicas on corrosion prevention coatings. Furthermore, a systematic approach to modifying and testing both powders and top coats of corrosion prevention systems is presented.

Armstrong, Beth L [ORNL] [ORNL; Pawel, Steven J [ORNL] [ORNL; Hunter, Scott Robert [ORNL] [ORNL; Haynes, James A [ORNL] [ORNL; Hillesheim, Daniel A [ORNL] [ORNL

2013-01-01T23:59:59.000Z

235

Density hysteresis of heavy water confined in a nanoporous silica matrix  

E-Print Network [OSTI]

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 ...

Faraone, Antonio

236

Effectiveness of cabs for dust and silica control on mobile mining equipment  

SciTech Connect (OSTI)

The Mine Safety and Health Administration (MSHA) has conducted a study to evaluate the effectiveness of cabs for controlling silica dust exposure during operation of mobile mining equipment. This study focused on bulldozers, front-end loaders and haul trucks, was conducted at surface coal mining operations and underground metal and nonmetal mining operations. Each piece of equipment tested was equipped with a cab. The vehicles sampled were from a range of manufacturers having different types of filter media and air intake configurations. The purpose of this study was to determine the reduction of dust and silica exposure that could be achieved through the use of a well-maintained cab. For each piece of equipment, dust and silica concentrations inside and outside the cab were determined and compared. In some cases, filtration efficiencies could be calculated. A properly designed environmental cab is sealed, has an intake air filtration system, and a heating and cooling system. Cabs should have good seals around the doors and windows. Factors such as cab pressurization filtration systems, filter media, and maintenance practices were also examined. In some cases, dust and silica reduction of 90 to 95% were observed.

Garcia, J.J.; Gresh, R.E.; Gareis, M.B.; Haney, R.A.

1999-07-01T23:59:59.000Z

237

Silica Supported Single-Walled Carbon Nanotubes as a Modifier in Polyethylene Composites  

E-Print Network [OSTI]

Silica Supported Single-Walled Carbon Nanotubes as a Modifier in Polyethylene Composites Neal D. Mc.interscience.wiley.com). ABSTRACT: Composites have been made from single- wall carbon nanotubes in a polyethylene (PE) matrix: additives; composites; conducting polymers; nanocomposites; polyethylene INTRODUCTION Polyethylene (PE

Resasco, Daniel

238

E-Print Network 3.0 - amorphous silica dissolution Sample Search...  

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

Microscopic Surface Processes Across Summary: No electrolytes 0.1 -2.3 670 0.0167 M CaCl2 0.65 -0.4 44 0.0167 M CaCl2 0.1 -2.3 4 12;DISSOLUTION OF SILICA... Kinetics of...

239

TESLA-FEL 2004-01 Silica Aerogel Radiators for Bunch Length  

E-Print Network [OSTI]

TESLA-FEL 2004-01 Silica Aerogel Radiators for Bunch Length Measurements J. B¨ahr a , V. Djordjadze aerogel are used to measure the electron bunch length at the photo injector test facility at DESY Zeuthen by the usage of aerogel is calculated analytically and Monte Carlo simulations are performed. It is shown

240

Acidity and catalytic activity of zeolite catalysts bound with silica and alumina  

E-Print Network [OSTI]

. Micropore surface area and micropore volume are reduced by about 19% and 18%, respectively, indicating some micropores of ZSM-5 are blocked on binding with silica. SiO2-bound ZSM-5 catalysts have less catalytic activity for butane transformation (cracking...

Wu, Xianchun

2004-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Characterization of the intrinsic strength between epoxy and silica using a multiscale approach  

E-Print Network [OSTI]

, we report a model to predict the intrinsic strength between organic and inorganic materials, based energy surface between attached and detached states of the bonded system and scaled up to incorporate readily in many other polymers. Silica, commonly found material in nature in the form of sand or quartz

Buehler, Markus J.

242

MODELING THE MEAN INTERACTION FORCES BETWEEN POWDER APPLICATION TO SILICA GEL-MAGNESIUM STEARATE MIXTURES.  

E-Print Network [OSTI]

1 MODELING THE MEAN INTERACTION FORCES BETWEEN POWDER PARTICLES. APPLICATION TO SILICA GEL-MAGNESIUM) particles (d50 = 55 µm) were coated with fine invited particles of magnesium stearate (MS, d50 = 4.6 µm. Interaction forces between the material attached to the cantilever (Magnesium Stearate MS) and the surface

Paris-Sud XI, Université de

243

Fluorocarbon plasma etching and profile evolution of porous low-dielectric-constant silica  

E-Print Network [OSTI]

of PS, a feature profile model has been integrated with a plasma equipment model. To focus on issuesFluorocarbon plasma etching and profile evolution of porous low-dielectric-constant silica Arvind silicon dioxide PS is one such material. To address scaling issues during fluorocarbon plasma etching

Kushner, Mark

244

Plasticity-induced structural anisotropy of silica glass C. L. Rountree1  

E-Print Network [OSTI]

Plasticity-induced structural anisotropy of silica glass C. L. Rountree1 , D. Vandembroucq2 , M anisotropic structure after extended shear plastic flow. This anisotropy which survives for an un- stressed tetrahedra microstructure remains mostly unaltered. PACS numbers: 62.20.F, 81.05.Kf Plasticity of amorphous

Boyer, Edmond

245

EPR study of the adsorption of dioxin vapours onto microporous carbons and mesoporous silica  

E-Print Network [OSTI]

EPR study of the adsorption of dioxin vapours onto microporous carbons and mesoporous silica M 31 October 2010 Keywords: EPR AC MTS Surface characterization Dioxin a b s t r a c t Computer aided with a nitroxide radical (TCDD-T) was employed to investigate the adsorption of dioxin vapours onto two carbons

Turro, Nicholas J.

246

EFFECTS OF SAND AND SILICA FUME ON THE VIBRATION DAMPING BEHAVIOR OF CEMENT  

E-Print Network [OSTI]

. The silica fume (Elkem Materials, Inc., Pittsburgh, PA, EMS 965) was used in the amount of 15% by weight 14260-4400, USA (Received February 6, 1998; in final form June 26, 1998) ABSTRACT The addition of sand. 10, pp. 1353­1356, 1998 Copyright © 1998 Elsevier Science Ltd Printed in the USA. All rights reserved

Chung, Deborah D.L.

247

The fatigue of high-strength fused silica optical fibers in low humidity q  

E-Print Network [OSTI]

the effect of humidity on the kinetics of subcritical crack growth in high strength optical fibers that the rate of subcritical crack growth is given by dc dt ¼ A exp n KI KIC ; ð1� where A and n are fatigue by assuming a simple chemical kinetics model for fatigue in which the reaction rate between water and silica

Matthewson, M. John

248

Activation energy and entropy of dynamic fatigue of pristine silica optical fibers  

E-Print Network [OSTI]

, NJ 08 854-8065 ABSTRACT Subcritical crack growth in fused silica can be modeled as a stress assisted chemical reaction between water and strained bonds at the crack tip. The stress influences the crack growth which has been most commonly used for brittle ceramic materials is the well-known subcritical crack

Matthewson, M. John

249

CHEMICAL KINETICS MODELS FOR THE FATIGUE BEHAVIOR OF FUSED SILICA OPTICAL FIBER  

E-Print Network [OSTI]

of stress, temperature and activity of the corroding species (e.g. water). A power law degradation kinetics the degradation depends on the applied stress. Subcritical Crack Growth Model The reliability of silica optical fiber under stress is usually described by the subcritical crack growth model. It is assumed

Matthewson, M. John

250

THE EFFECT OF TEMPERATURE AND UNIAXIAL PRESSURE ON THE DENSIFICATION BEHAVIOR OF SILICA AEROGEL GRANULES  

SciTech Connect (OSTI)

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 Technology Separations and Waste Forms Campaign. The silver-functionalized silica aerogel proved to be an excellent candidate for this treatment because of its high selectivity and sorption capacity for radioiodine and its possible conversion to a durable silica-based waste form. The present study investigated with nitrogen sorption and helium pycnometry the effect of pressureless isothermal sintering at temperatures of 900-1400°C for 2.5-90 min or isothermal hot-pressing at 1200°C for 2.5 min on densification of raw and silver-functionalized silica aerogel granules. Rapid sintering was observed at 1050 and 1200°C. Only 15 min of pressureless sintering at 1200°C resulted in almost complete densification. The macropores disappeared, surface area decreased from 1114 m2/g to 25 m2/g, pore volume from 7.41 cm3/g to 0.09 cm3/g, and adsorption pore size from 18.7 to 7 nm. The skeletal density of sintered granules was similar to the bulk density of amorphous silica (2.2 g/cm3). The hot-pressing accelerated the sintering process, decreasing significantly the pore size and volume.

Matyas, Josef; Robinson, Matthew J.; Fryxell, Glen E.

2012-10-01T23:59:59.000Z

251

Acoustic and Thermal Characterization of Oil Migration, Gas Hydrates Formation and Silica Diagenesis  

E-Print Network [OSTI]

Acoustic and Thermal Characterization of Oil Migration, Gas Hydrates Formation and Silica Rights Reserved #12;ABSTRACT Acoustic and Thermal Characterization of Oil Migration, Gas Hydrates-A to Opal-CT, the formation of gas hydrates, fluid substitution in hydrocarbon reservoirs, and fluid

Guerin, Gilles

252

Determination of silica scale deposition rates and thresholds applied toward protection of injection reservoirs. Quarterly progress report, July 1--September 30, 1998  

SciTech Connect (OSTI)

The program objective aims to identify the highest temperature at which silica scale will develop from partially evaporated and significantly cooled geothermal liquid. The approach involves tracking deposition of silica scale by monitoring the apparent electrical conductivity of the geothermal liquid in an isolation chamber. A decrease in apparent conductivity occurs because silica deposited on electrode surfaces is less conductive than the geothermal liquid. The major technical hurdle is building a conductivity monitoring system that is sensitive enough to distinguish between no silica deposition and almost no silica deposition, while accounting for other factors which also affect conductivity, such as temperature and varying fluid composition.

NONE

1998-11-01T23:59:59.000Z

253

Silica Supported Ceria Nanoparticles: A Hybrid Nanostructure To Increase Stability And Surface Reactivity Of Nano-crystalline Ceria  

SciTech Connect (OSTI)

The mixed oxidation state (3+/4+) of ceria nanoparticles of smaller sizes make them attractive materials for their catalytic antioxidant biological properties. However the unmodified smaller ceria nanoparticles are limited in their use due to particles agglomeration and reduced surface chemical reactivity in the solutions used to disperse the nanoparticles. This work describes an effort to stabilize small ceria nanoparticles, retaining their desired activity, on a larger stable silica support. The ceria nanoparticles attached to silica was synthesized by a solution synthesis technique in which the surface functional groups of silica nanoparticles were found to be essential for the formation of smaller ceria nanoparticles. The surface chemical and vibrational spectroscopy analysis revealed cerium–silicate (Ce-O-Si) covalent bond linkage between silica and cerium oxide nanoparticles. The colloidal properties (agglomerate particle size and suspension stability) of ceria attached to silica was significantly improved due to inherent physico-chemical characteristics of silica against random collision and gravitation settling as opposed to unmodified ceria nanoparticles in solution. The bio-catalytic activity of ceria nanoparticles in the 3+ oxidation state was not found to be limited by attachment to the silica support as measured by free radical scavenging activity in different biological media conditions.

Munusamy, Prabhakaran; Sanghavi, Shail P.; Varga, Tamas; Thevuthasan, Suntharampillai

2014-01-21T23:59:59.000Z

254

Biological Applications and Transmission Electron Microscopy Investigations of Mesoporous Silica Nanoparticles  

SciTech Connect (OSTI)

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.

Brian G. Trewyn

2006-05-01T23:59:59.000Z

255

Mechanical relaxation behavior of polyurethanes reinforced with the in situ-generated sodium silica-polyphosphate nanophase  

E-Print Network [OSTI]

Further exploration of hybrid organic/inorganic composites (polyurethane based with inorganic material sodium silica polyphosphate) properties with mechanical relaxometer gives ability to analyze microstructure of such materials in terms of chain reptation tubes filler's fractal aggregates and stress amplification.

V. O. Dupanov; S. M. Ponomarenko

2014-10-31T23:59:59.000Z

256

Visible Light Absorption of Binuclear TiOCoII Charge-Transfer Unit Assembled in Mesoporous Silica  

E-Print Network [OSTI]

Ti-MCM-41 silica in acetonitrile solution affords binucleardirectly dissolved in acetonitrile (50 mL) in a Schlenk tubeupon dissolving CoCl 2 in acetonitrile is believed to be the

Han, Hongxian; Frei, Heinz

2008-01-01T23:59:59.000Z

257

The role of effective stress on silica solubility and pressure solution: an experimental investigation in a flow-through system  

E-Print Network [OSTI]

THE ROLE OF EFFECTIVE STRESS ON SILICA SOLUBILITY AND PRESSURE SOLUTION: AN EXPERIMENTAL INVESTIGATION IN A FLOW-THROUGH SYSTEM A Thesis by BRIAN PATRICK ELIAS Submitted to the Office of Graduate Studies of Texas A&M University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1989 Major Subject: Geology THE ROLE OF EFFECTIVE STRESS ON SILICA SOLUBILITY AND PRES SURE SOLUTION: AN EXPERIMENTAL INVESTIGATION IN A FLOW-THROUGH SYSTEM A Thesis by BRIAN...

Elias, Brian Patrick

2012-06-07T23:59:59.000Z

258

Infrared spectroscopic study of the adsorption of carbon monoxide on silica-supported copper oxide  

SciTech Connect (OSTI)

Adsorption of carbon monoxide at room temperature (0.1 to 50 Torr) on silica-supported copper oxide was studied by infrared spectroscopy. Catalysts were prepared by deposition-precipitation or impregnation. After calcination two types of adsorbed CO were identified showing absorption bands at 2136 +- 3 and 2204 +- 1 cm/sup -1/, which are ascribed to CO adsorbed on copper(II) oxide and on isolated copper(II) ions in the silica surface, respectively. Reduction and reoxidation removed the band at 2204 cm/sup -1/ with all samples and raised the intensity of the 2136-cm/sup -1/ band with the precipitated catalysts but not with the impregnation catalyst. Evidence is brought forward that the isolated copper ions are mobilized during reduction and generate new copper (oxide) surface. The change in background transmission of the samples could be used to obtain further information about the interaction of O/sub 2/ and CO with copper oxide.

De Jong, K.P.; Geus, J.W.; Joziasse, J.

1980-10-01T23:59:59.000Z

259

Lasing characteristics of Er/sup 3 +/-doped silica fibers from 1553 up to 1603 nm  

SciTech Connect (OSTI)

The laser oscillations from 1553 up to 1603 nm have been demonstrated in Er/sup 3 +/-doped silica fibers with a doping rate of 2500 ppm. Wide changes in laser oscillation wavelengths are due to broad splitting of the upper sublevels in the /sup 4/I/sub 152/ manifold, caused by the random structure of the silica matrix. It has been shown that unpumped parts of the Er/sup 3 +/ ions in the end pumped fiber laser configuration play an important role in the wavelength changes of the laser oscillation. For an absorbed pump power of 320 mW at 514 nm, output power of 0.5 mW was obtained at 1603 nm.

Kimura, Y.; Nakazawa, M.

1988-07-15T23:59:59.000Z

260

Gamma radiation-induced refractive index change in Ge- and N-doped silica  

SciTech Connect (OSTI)

We measured the change of the refractive index over a wide wavelength range in Ge- and N-doped high purity (fiber optics grade) silica glasses subjected to gamma irradiation. The radiation-induced change of the refractive index tends to be greater in the infrared part of the spectrum compare to the values measured in the UV-visible part of the spectrum. By means of the Kramers-Kronig relations, we estimate that a weak broadening of the optical vibration band of the silica network adds to this effect. The paper also discusses the difference observed in the spectral behavior of the induced refractive index change for both types of doped glass.

Brichard, Benoit [SCK-CEN-Belgian Nuclear Research Center, Boeretang 200, 2400 Mol (Belgium); Butov, Oleg V.; Golant, Konstantin M. [Fiber Optics Research Center, Russian Academy of Sciences, Vavilov Street 38, 119991 Moscow (Russian Federation); Fernandez Fernandez, Alberto [Masterminds Ltd., rue du Temple 40, CH-2800 Delemont (Switzerland)

2008-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Study of a Threshold Cherenkov Counter Based on Silica Aerogels with Low Refractive Indices ?  

E-Print Network [OSTI]

To identify ? ± and K ± in the region of 1.0 ? 2.5 GeV/c, a threshold Cherenkov counter equipped with silica aerogels has been investigated. Silica aerogels with a low refractive index of 1.013 have been successfully produced using a new technique. By making use of these aerogels as radiators, we have constructed a Cherenkov counter and have checked its properties in a test beam. The obtained results have demonstrated that our aerogel was transparent enough to make up for loss of the Cherenkov photon yield due to a low refractive index. Various configurations for the photon collection system and some types of photomultipliers, such as the fine-mesh type, for a read out were also tested. From these studies, our design of a Cherenkov counter dedicated to ?/K separation up to a few GeV/c with an efficiency greater than 90 % was considered. 1

I. Adachi; T. Sumiyoshi; K. Hayashi; N. Iida; R. Enomoto; K. Tsukada; R. Suda; S. Matsumoto; K. Natori; M. Yokoyama; H. Yokogawa

1994-01-01T23:59:59.000Z

262

High-Q silica zipper cavity for optical radiation pressure driven MOMS switch  

SciTech Connect (OSTI)

We design a silica zipper cavity that has high optical and mechanical Q (quality factor) values and demonstrate numerically the feasibility of a radiation pressure driven micro opto-mechanical system (MOMS) directional switch. The silica zipper cavity has an optical Q of 4.0 × 10{sup 4} and an effective mode volume V{sub mode} of 0.67?{sup 3} when the gap between two cavities is 34 nm. The mechanical Q (Q{sub m}) is determined by thermo-elastic damping and is 2.0 × 10{sup 6} in a vacuum at room temperature. The opto-mechanical coupling rate g{sub OM} is as high as 100 GHz/nm, which allows us to move the directional cavity-waveguide system and switch 1550-nm light with 770-nm light by controlling the radiation pressure.

Tetsumoto, Tomohiro; Tanabe, Takasumi, E-mail: takasumi@elec.keio.ac.jp [Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi Kohoku, Yokohama 223-8522 (Japan)

2014-07-15T23:59:59.000Z

263

Magnetic properties of mesoporous cobalt-silica-alumina ternary mixed oxides  

SciTech Connect (OSTI)

Mesoporous cobalt-silica-alumina mixed oxides with variable cobalt content have been synthesized through slow evaporation method by using Pluronic F127 non-ionic surfactant as template. N{sub 2} sorption analysis of the template-free mixed oxide samples revealed that these mesoporous materials have high BET surface areas together with large mesopores. Powder XRD, TEM, EDS, FT IR and EPR spectroscopic analysis have been employed to understand the nature of the mesophases, bonding and composition of the materials. Low temperature magnetic measurements of these mixed oxide materials show the presence of ferromagnetic correlation at elevated temperature though at low temperature paramagnetic to ferrimagnetic transition is observed. Highlights: Black-Right-Pointing-Pointer Mesoporous cobalt-silica-alumina ternary mixed oxides. Black-Right-Pointing-Pointer High surface area and mesoporosity in magnetic materials. Black-Right-Pointing-Pointer Ferromagnetic correlation at elevated temperature. Black-Right-Pointing-Pointer Low temperature paramagnetic to ferrimagnetic transition.

Pal, Nabanita [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)] [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Seikh, Md. Motin [Department of Chemistry, Visva-Bharati University, Santiniketan, West Bengal (India)] [Department of Chemistry, Visva-Bharati University, Santiniketan, West Bengal (India); Bhaumik, Asim, E-mail: msab@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)] [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)

2013-02-15T23:59:59.000Z

264

Laser-driven formation of a high-pressure phase in amorphous silica  

SciTech Connect (OSTI)

A combination of electron diffraction and infrared reflectance measurements shows that synthetic silica transforms partially into stishovite under high-intensity (GW/cm2) laser irradiation, probably by the formation of a dense ionized plasma above the silica surface. During the transformation the silicon coordination changes from four-fold to six-fold and the silicon-oxygen bond changes from mostly covalent to mostly ionic, such that optical properties of the transformed material differ significantly from those of the original glass. This phase transformation offers one suitable mechanism by which laser-induced damage grows catastrophically once initiated, thereby dramatically shortening the service lifetime of optics used for high-power photonics applications such as inertial confinement fusion.

Salleo, Alberto; Taylor, Seth T.; Martin, Michael C.; Panero, Wendy R.; Jeanloz, Raymond; Genin, Francois Y.; Sands, Timothy

2002-05-31T23:59:59.000Z

265

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

SciTech Connect (OSTI)

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.

Holleis, S.; Hoinkes, T.; Wuttke, C.; Schneeweiss, P.; Rauschenbeutel, A. [Vienna Center for Quantum Science and Technology, TU Wien—Atominstitut, Stadionallee 2, 1020 Vienna (Austria)

2014-04-21T23:59:59.000Z

266

Molecular-dynamics simulations of thin polyisoprene films confined between amorphous silica substrates  

SciTech Connect (OSTI)

Constant temperature–constant pressure (NpT) molecular-dynamics computer simulations have been carried out for the united-atom model of a non-crosslinked (1,4) cis-polyisoprene (PI) melt confined between two amorphous, fully coordinated silica surfaces. The Lennard-Jones 12-6 potential was implemented to describe the polymer–silica interactions. The thickness H of the produced PI–silica film has been varied in a wide range, 1 < H/R{sub g} < 8, where R{sub g} is the individual PI chain radius of gyration measured under the imposed confinement. After a thorough equilibration, the PI film stratified structure and polymer segmental dynamics have been studied. The chain structure in the middle of the films resembles that in a corresponding bulk, but the polymer-density profile shows a pronounced ordering of the polymer segments in the vicinity of silica surfaces; this ordering disappears toward the film middles. Tremendous slowing down of the polymer segmental dynamics has been observed in the film surface layers, with the segmental relaxation more than 150 times slower as compared to that in a PI bulk. This effect increases with decreasing the polymer-film thickness. The segmental relaxation in the PI film middles shows additional relaxation process which is absent in a PI bulk. Even though there are fast relaxation processes in the film middle, its overall relaxation is slower as compared to that in a bulk sample. The interpretation of the results in terms of polymer glassy bridges has been discussed.

Guseva, D. V., E-mail: d.v.guseva@tue.nl [Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven (Netherlands); Physics Department, Chair of Polymer and Crystal Physics, M. V. Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Komarov, P. V. [Department of Theoretical Physics, Tver State University, Sadovyj per. 35, 170002 Tver, Russia and Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova st. 28, 119991 Moscow (Russian Federation)] [Department of Theoretical Physics, Tver State University, Sadovyj per. 35, 170002 Tver, Russia and Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova st. 28, 119991 Moscow (Russian Federation); Lyulin, Alexey V. [Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven (Netherlands)] [Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven (Netherlands)

2014-03-21T23:59:59.000Z

267

Silica coated magnetite nanoparticles for removal of heavy metal ions from polluted waters  

E-Print Network [OSTI]

Magnetic removal of Hg2+ and other heavy metal ions like Cd2+, Pb2+ etc. using silica coated magnetite particles from polluted waters is a current topic of active research to provide efficient water recycling and long term high quality water. The technique used to study the bonding characteristics of such kind of nanoparticles with the heavy metal ions is a very sensitive hyperfine specroscopy technique called the perturbed angular correlation technique (PAC).

Dash, Monika

2013-01-01T23:59:59.000Z

268

A New Concept for the Fabrication of Hydrogen Selective Silica Membranes  

SciTech Connect (OSTI)

We are attempting to fabricate H{sub 2}-selective silica-based films by ''layer-by-layer'' deposition as a new approach for thin films. A sonication-assisted deposition method was mainly used for ''layer-by-layer'' deposition. In addition, other approaches such as a dip-coating and the use of a polymer matrix with a layered silicate were contrived as well. This report shows the progress done during the 2nd Year of this award.

Michael Tsapatsis

2006-07-31T23:59:59.000Z

269

Effects from Alkali-Silica Reacton and Delayed Ettringite Formation on Reinforced Concrete Column Lap Splices  

E-Print Network [OSTI]

EFFECTS FROM ALKALI-SILICA REACTION AND DELAYED ETTRINGITE FORMATION ON REINFORCED CONCRETE COLUMN LAP SPLICES A Thesis by MARY KATHLEEN ECK Submitted to the Office of Graduate Studies of Texas A&M University in partial... by MARY KATHLEEN ECK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Joseph M. Bracci Committee Members...

Eck, Mary

2012-07-16T23:59:59.000Z

270

Structural Assessment of D-Regions Affected by Alkali-Silica Reaction/Delayed Ettringite Formation  

E-Print Network [OSTI]

STRUCTURAL ASSESSMENT OF D-REGIONS AFFECTED BY ALKALI- SILICA REACTION/DELAYED ETTRINGITE FORMATION A Dissertation by SHIH-HSIANG LIU Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee, Joseph M. Bracci Committee Members, John B. Mander Stefan Hurlebaus Harry A. Hogan Head of Department, John M. Niedzwecki December 2012 Major Subject: Civil...

Liu, Shih-Hsiang 1979-

2012-11-12T23:59:59.000Z

271

Thermal transport in CO2 laser irradiated fused silica: in situ measurements and analysis  

SciTech Connect (OSTI)

In situ spatial and temporal temperature measurements of pristine fused silica surfaces heated with a 10.6 {micro}m CO{sub 2} laser were obtained using an infrared radiation thermometer based on a Mercury Cadmium Telluride (MCT) camera. Laser spot sizes ranged from 250 {micro}m to 1000 {micro}m diameter with peak axial irradiance levels of 0.13 to 16 kW/cm{sup 2}. For temperatures below 2800K, the measured steady-state surface temperature is observed to rise linearly with both increasing beam size and incident laser irradiance. The effective thermal conductivity estimated over this range was approximately 2W/mK, in good agreement with classical calculations based on phonon heat capacities. Similarly, time-dependent temperature measurements up to 2000K yielded thermal diffusivity values which were close to reported values of 7 x 10{sup -7} m{sup 2}/s. Above {approx}2800K, the fused silica surface temperature asymptotically approaches 3100K as laser power is further increased, consistent with the onset of evaporative heat losses near the silica boiling point. These results show that in the laser heating regime studied here, the T{sup 3} temperature dependent thermal conductivity due to radiation transport can be neglected, but at temperatures above 2800K heat transport due to evaporation must be considered. The thermal transport in fused silica up to 2800K, over a range of conditions, can then be adequately described by a linear diffusive heat equation assuming constant thermal properties.

Yang, S T; Matthews, M J; Elhadj, S; Draggoo, V G; Bisson, S E

2009-07-07T23:59:59.000Z

272

Detection of alkali-silica reaction swelling in concrete by staining  

DOE Patents [OSTI]

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.

Guthrie, Jr., George D. (Santa Fe, NM); Carey, J. William (Santa Fe, NM)

1998-01-01T23:59:59.000Z

273

Detection of alkali-silica reaction swelling in concrete by staining  

DOE Patents [OSTI]

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.

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

1998-04-14T23:59:59.000Z

274

Influence of phosphate and silica on U(VI) precipitation from acidic and neutralized wastewaters  

SciTech Connect (OSTI)

Uranium speciation and physical-chemical characteristics were studied in solids precipitated from synthetic acidic to circumneutral wastewaters in the presence and absence of dissolved silica and phosphate to examine thermodynamic and kinetic controls on phase formation. Composition of synthetic wastewater was based on disposal sites 216-U-8 and 216-U-12 Cribs at the Hanford site (WA, USA). In the absence of dissolved silica or phosphate, crystalline or amorphous uranyl oxide hydrates, either compreignacite or meta-schoepite, precipitated at pH 5 or 7 after 30 d of reaction, in agreement with thermodynamic calculations. In the presence of 1 mM dissolved silica representative of groundwater concentrations, amorphous phases dominated by compreignacite precipitated rapidly at pH 5 or 7 as a metastable phase and formation of poorly-crystalline boltwoodite, the thermodynamically stable uranyl silicate phase, was slow. In the presence of phosphate (3 mM), meta-ankoleite initially precipitated as the primary phase at pH 3, 5, or 7 regardless of the presence of 1 mM dissolved silica. Analysis of precipitates by U LIII-edge EXAFS indicated that “autunite-type” sheets of meta-ankoleite transformed to “phosphuranylite-type” sheets after 30 d of reaction, probably due to Ca substitution in the structure. Low solubility of uranyl phosphate phases limits dissolved U(VI) concentrations but differences in particle size, crystallinity, and precipitate composition vary with pH and base cation concentration, which will influence the thermodynamic and kinetic stability of these phases.

Kanematsu, Masakazu; Perdrial, Nicolas; Um, Wooyong; Chorover, Jon; O'Day, Peggy A.

2014-04-22T23:59:59.000Z

275

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

SciTech Connect (OSTI)

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.

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

1996-09-01T23:59:59.000Z

276

Sulfate Fining Chemistry in Oxidized and Reduced Soda-Lime-Silica Glasses  

SciTech Connect (OSTI)

Various reducing agents were used and their additions were varied to (1) increase glass quality through eliminating defects from silica scum, (2) decrease SOx emissions through changing the kind and quantity of reducing agents, and (3) improve production efficiency through increased flexibility of glass redox control during continuous processing. The work included measuring silica sand dissolution and sulfate decomposition in melts from glass batches. Glass batches were heated at a temperature-increase rate deemed similar to that experienced in the melting furnace. The sulfate decomposition kinetics was investigated with thermogravimetric analysis-differential thermal analysis and evolved gas analysis. Sulfur concentrations in glasses quenched at different temperatures were determined using X-ray fluorescence spectroscopy. The distribution of residual sand (that which was not dissolved during the initial batch reactions) in the glass was obtained as a function of temperature with optical microscopy in thin-sections of melts. The fraction of undissolved sand was measured with X-ray diffraction. The results of the present study helped Visteon Inc. reduce the energy consumption and establish the batch containing 0.118 mass% of graphite as the best candidate for Visteon glass production. The improved glass batch has a lower potential for silica scum formation and for brown fault occurrence in the final glass product. It was established that bubbles trapped in the melt even at 1450 C have a high probability to be refined when reaching the hot zone in the glass furnace. Furthermore, silica sand does not accumulate at the glass surface and dissolves faster in the batch with graphite than in the batch with carbocite.

Matyas, Josef; Hrma, Pavel R.

2005-05-13T23:59:59.000Z

277

Sol-gel processed silica-alumina materials for diesel engine emission reduction catalysts  

SciTech Connect (OSTI)

The incorporation of >30% silica in alumina prior to platinum impregnation improves the NOx conversion efficiency in the 200--300 C range from 45 to 57% and reduces light-off temperature. Further increase in the amount of silica to 50% is detrimental to NOx conversion efficiency. The {sup 1}H and {sup 29}Si NMR of the materials suggest that this trend is probably related to the surface acidity. The analyses of these materials by X-ray powder diffraction and electron microscopy do not reveal significant differences. Additional NOx conversion in the 350--450 C range with a maximum of 30% at 400 C can be achieved if a rhodium-impregnated 30% silica-alumina, Rh-30% SiO{sub 2}-Al{sub 2}O{sub 3}, is placed upstream of Pt-30% SiO{sub 2}-Al{sub 2}O{sub 3}. It is important to note that mixing Pt-30% SiO{sub 2}-Al{sub 2}O{sub 3} with Rh-30% SiO{sub 2}-Al{sub 2}O{sub 3} does not enhance conversion efficiency or effective temperature range.

Narula, C.K.; Rokosz, M.; Allard, L.F.; Kudla, R.J.; Chattha, M.S.

2000-04-18T23:59:59.000Z

278

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

SciTech Connect (OSTI)

In this work, we describe the controlled synthesis of novel heterogeneous nanostructures comprised of mesoporous silica-coated gold nanorods (MSGNRs) in the form of core–shell nanolollipops and nanodumb-bells, using a seed-mediated sol–gel method. Although MSGNR core–shell (?-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.

Huang, Ching-Mao [Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli 35053, Taiwan (China); Material and Chemical Laboratories, Industrial Technology Research Institute, Hsinchu 30011, Taiwan (China); Chung, Ming-Fang; Lo, Leu-Wei, E-mail: lwlo@nhri.org.tw [Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli 35053, Taiwan (China); Souris, Jeffrey S. [Department of Radiology, The University of Chicago, Chicago, Illinois 60637 (United States)

2014-11-01T23:59:59.000Z

279

Dendrimer Templated Synthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole Hydrogenation.  

E-Print Network [OSTI]

Scheme 2) and pyrrole hydrogenation (Scheme 3). Synthesis ofSynthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole

Huang, Wenyu

2009-01-01T23:59:59.000Z

280

Magnetic properties of magnetite nanoparticles coated with mesoporous silica by sonochemical method  

SciTech Connect (OSTI)

Highlights: Black-Right-Pointing-Pointer MCM-41-coating of magnetite nanoparticles performed under ultrasonic irradiation. Black-Right-Pointing-Pointer Ultrasonic irradiation accelerates the formation of the MCM-41 framework. Black-Right-Pointing-Pointer The hysteretic response to an applied field was investigated applying FORC diagram. Black-Right-Pointing-Pointer The average coercive field of the Fe{sub 3}O{sub 4} nanoparticles increased after coating. -- Abstract: In this paper we present the magnetic properties of mesoporous silica-coated Fe{sub 3}O{sub 4} nanoparticles. The coating of magnetite nanoparticles with mesoporous silica shell was performed under ultrasonic irradiation. The obtained mesoporous silica-coated magnetite nanoparticles were characterized by powder X-ray diffraction, focused ion beam-scanning electron microscopy, nitrogen adsorption-desorption isotherms and vibrating sample magnetometer. The hysteretic behavior was studied using first-order reversal curves diagrams. The X-ray diffraction result indicates that the extreme chemical and physical conditions created by acoustic cavitations have an insignificant effect on crystallographic structural characteristic of magnetite nanoparticles. Changes in the coercivity distributions of the magnetite nanoparticles were observed on the first-order reversal curves diagrams for the samples with coated particles compared with the samples containing uncoated particles of magnetite. The coated particles show an increased most probable coercivity of about 20% compared with the uncoated particles which can be associated with an increased anisotropy due to coating even if the interaction field distribution measured on the diagrams are virtually identical for coated/uncoated samples.

Ursachi, Irina [Department of Physics and CARPATH Center, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania)] [Department of Physics and CARPATH Center, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania); Vasile, Aurelia [Department of Chemistry, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania)] [Department of Chemistry, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania); Chiriac, Horia [National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania)] [National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania); Postolache, Petronel [Department of Physics and CARPATH Center, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania)] [Department of Physics and CARPATH Center, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania); Stancu, Alexandru, E-mail: alstancu@uaic.ro [Department of Physics and CARPATH Center, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania)] [Department of Physics and CARPATH Center, 'Alexandru Ioan Cuza' University of Iasi, 11 Carol I Blvd., 700506 Iasi (Romania)

2011-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Reduction and aggregation of silver in aqueous gelatin and silica suspensions  

SciTech Connect (OSTI)

The investigation of silver reduction and aggregation processes are of specific interest to the photographic industry, which relies heavily on photochemical equivalents of these reactions. Mechanistic insights into the formation of small silver clusters in aqueous solution have been obtained from both pulse and {gamma}-radiolytic studies. This paper examines the reduction of silver ions and the subsequent formation of silver clusters in aqueous gelatin solutions and on colloidal silica particles using the pulse radiolysis technique. The aggregation processes are compared with the parallel reactions in aqueous solutions.

Kapoor, S.; Lawless, D.; Kennepohl, P.; Meisel, D. [Argonne National Lab., IL (United States); Serpone, N. [Concordia Univ., Montreal, Quebec (Canada)

1994-06-01T23:59:59.000Z

282

Continuous process preparation of activated silica with low carbon dioxide content gas  

E-Print Network [OSTI]

Iiroduced. Activated silica is the term used to designate a negatively charged colloidal particle formed by the reactien of a dilute sodium silicate solution with a dilute solution of' an acidic material or other activant. Used as a coagulant sid to alum.... paylis (5) at Chicago found that, sodium silicate could. 'be used with paper maker's alum (aluminum sulfate) as an effective c~t aid. in treating Lake l4. chigan water. Since that time several. batch processes have been cleveloyed using various...

Burdett, Joseph Walton

1954-01-01T23:59:59.000Z

283

Femtosecond diffraction dynamics of laser-induced periodic surface structures on fused silica  

SciTech Connect (OSTI)

The formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration, 800 nm center wavelength) is studied experimentally using a transillumination femtosecond time-resolved (0.1 ps-1 ns) pump-probe diffraction approach. This allows to reveal the generation dynamics of near-wavelength-sized LIPSS showing a transient diffraction at specific spatial frequencies even before a corresponding permanent surface relief was observed. The results confirm that the ultrafast energy deposition to the materials surface plays a key role and triggers subsequent physical mechanisms such as carrier scattering into self-trapped excitons.

Hoehm, S.; Rosenfeld, A. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Strasse 2A, D-12489 Berlin (Germany)] [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Strasse 2A, D-12489 Berlin (Germany); Krueger, J.; Bonse, J. [BAM Bundesanstalt fuer Materialforschung und - pruefung, Unter den Eichen 87, D-12205 Berlin (Germany)] [BAM Bundesanstalt fuer Materialforschung und - pruefung, Unter den Eichen 87, D-12205 Berlin (Germany)

2013-02-04T23:59:59.000Z

284

Laser induced damage of fused silica polished optics due to a droplet forming organic contaminant  

SciTech Connect (OSTI)

We report on the effect of organic molecular contamination on single shot laser induced damage density at the wavelength of 351 nm, with a 3 ns pulse length. Specific contamination experiments were made with dioctylphthalate (DOP) in liquid or gaseous phase, on the surface of fused silica polished samples, bare or solgel coated. Systematic laser induced damage was observed only in the case of liquid phase contamination. Different chemical and morphological characterization methods were used to identify and understand the damage process. We demonstrate that the contaminant morphology, rather than its physicochemical nature, can be responsible for the decrease of laser induced damage threshold of optics.

Bien-Aime, Karell; Neauport, Jerome; Tovena-Pecault, Isabelle; Fargin, Evelyne; Labrugere, Christine; Belin, Colette; Couzi, Michel

2009-04-20T23:59:59.000Z

285

Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection  

SciTech Connect (OSTI)

The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu{sup 2+} as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on the surface of MSN and utilize them to complex cationic DNA. The p-EGFP-CI gene-coated MSN nanocomposite was able to transfect cancer cell lines, such as human HeLa and CHO cancer cell lines. The gene carrier ability of MSNs was further proved by transfecting primary cells and cotransfecting of two different genes in cancer cell lines. In sum, MSN are versatile partners in several types of applications.

Daniela Rodica Radu

2005-12-19T23:59:59.000Z

286

X-ray spectroscopy study of electronic structure of laser-irradiated Au nanoparticles in a silica film  

SciTech Connect (OSTI)

The electronic structure of gold nanoparticles embedded in a silica film is studied, both before and after irradiation at 355 nm by a laser. The Au 5d occupied valence states are observed by x-ray emission spectroscopy. They show that before irradiation the gold atoms are in metallic states within the nanoparticles. After irradiation with a fluence of 0.5 J/cm{sup 2}, it is found that gold valence states are close to those of a metal-poor gold silicide; thanks to a comparison of the experimental Au 5d states with the calculated ones for gold silicides using the density-functional theory. The formation of such a compound is driven by the diffusion of the gold atoms into the silica film upon the laser irradiation. At higher fluence, 1 J/cm{sup 2}, we find a higher percentage of metallic gold that could be attributed to annealing in the silica matrix.

Jonnard, P.; Bercegol, H.; Lamaignere, L.; Morreeuw, J.-P.; Rullier, J.-L.; Cottancin, E.; Pellarin, M. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, Centre National de la Recherche Scientifique Unite Mixte de Recherche (CNRS UMR) 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France); Commissariat a l'Energie Atomique/Centre d'Etudes Scientifiques et Techniques d'Aquitaine (CEA/CESTA), BP 2, F-33114, Le Barp (France); Centre Agregat Laboratoire de Spectrometrie Ionique et Moleculaire (LASIM) et Laboratoire de Physique de la Matiere Condensee et Nanostructures (LPMCN), Universite Claude Bernard Lyon I, F-69622 Villeurbanne (France)

2005-03-15T23:59:59.000Z

287

Formation of laser-induced periodic surface structures on fused silica upon two-color double-pulse irradiation  

SciTech Connect (OSTI)

The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of fused silica with multiple irradiation sequences consisting of laser pulse pairs (50 fs single-pulse duration) of two different wavelengths (400 and 800 nm) is studied experimentally. Parallel polarized double-pulse sequences with a variable delay ?t between ?10 and +10 ps and between the individual fs-laser pulses were used to investigate the LIPSS periods versus ?t. These two-color experiments reveal the importance of the ultrafast energy deposition to the silica surface by the first laser pulse for LIPSS formation. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS frequencies.

Höhm, S.; Herzlieb, M.; Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany)] [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J.; Bonse, J. [BAM Bundesanstalt für Materialforschung und –prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)] [BAM Bundesanstalt für Materialforschung und –prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

2013-12-16T23:59:59.000Z

288

The effect of silica gel sampling tube design on the analytical recovery of fluorine ions / by Daniel Howard Anna  

E-Print Network [OSTI]

concentrations of hydrofluoric acid. The statically generated concentrations ranged from 0. 5 to 2. 5 times the TLV. The first type of hand packed tube used foam, rather than glass wool, to hold the silica gel in place. The other type had silica gel sections... and the analyzed concentrations showed that the tubes were not statistically different at the 95% confidence level. ACKNOWLEDGMENT I would like to thank the members of my committee, Richard B. Konzen, Ph. D. , John P. Wagner, Ph. D. and Calvin B. Parnell, Ph. D...

Anna, Daniel Howard

1991-01-01T23:59:59.000Z

289

Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports  

E-Print Network [OSTI]

We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m.

Vienne, G; Jakobsen, C; Deyerl, H J; Jensen, J B; Sorensen, T; Hansen, T P; Huang, Y; Terrel, M; Lee, R K; Mortensen, N A; Broeng, J; Simonsen, H; Bjarklev, A; Yariv, A

2004-01-01T23:59:59.000Z

290

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

SciTech Connect (OSTI)

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 Angström 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.

Muthukumar, Kaliappan; Valentí, Roser; Jeschke, Harald O. [Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main (Germany)] [Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main (Germany)

2014-05-14T23:59:59.000Z

291

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

SciTech Connect (OSTI)

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.

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

2012-01-19T23:59:59.000Z

292

Molecular dynamics simulation of shock induced ejection on fused silica surface  

SciTech Connect (OSTI)

Shock response and surface ejection behaviors of fused silica are studied by using non-equilibrium molecular dynamics combining with the Tersoff potential. First, bulk structure and Hugoniot curves of fused silica are calculated and compared with experimental results. Then, the dynamical process of surface ejection behavior is simulated under different loading velocities ranging from 3.5 to 5.0?km?s, corresponding to shock wave velocities from 7.1 to 8.8?km?s. The local atomistic shear strain parameter is used to describe the local plastic deformation under conditions of shock compression or releasing. Our result shows that the shear strain is localized in the bottom area of groove under the shock compression. Surface ejection is observed when the loading velocity exceeds 4.0?km?s. Meanwhile, the temperature of the micro-jet is ?5574.7?K, which is close to experiment measurement. Several kinds of structural defects including non-bridging oxygen are found in the bulk area of the sample after ejection.

Su, Rui [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Xiang, Meizhen; Jiang, Shengli [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Chen, Jun, E-mail: jun-chen@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Center for Applied Physics and Technology, Peking University, Beijing 100087 (China); Wei, Han [Research Center of Laser Fusion, Mianyang 621900 (China)

2014-05-21T23:59:59.000Z

293

Interfacial water on crystalline silica: A comparative molecular dynamics simulation study  

SciTech Connect (OSTI)

All-atom molecular dynamics simulations were conducted to study the dynamics of aqueous electrolyte solutions confined in slit-shaped silica nanopores of various degrees of protonation. Five degrees of protonation were prepared by randomly removing surface hydrogen atoms from fully protonated crystalline silica surfaces. Aqueous electrolyte solutions containing NaCl or CsCl salt were simulated at ambient conditions. In all cases, the ionic concentration was 1 M. The results were quantified in terms of atomic density distributions within the pores, and the self-diffusion coefficient along the direction parallel to the pore surface. We found evidence for ion-specific properties that depend on ion surface, water ion, and only in some cases ion ion correlations. The degree of protonation strongly affects the structure, distribution, and the dynamic behavior of confined water and electrolytes. Cl ions adsorb on the surface at large degrees of protonation, and their behavior does not depend significantly on the cation type (either Na+ or Cs+ ions are present in the systems considered). The cations show significant ion-specific behavior. Na+ ions occupy different positions within the pore as the degree of protonation changes, while Cs+ ions mainly remain near the pore center at all conditions considered. For a given degree of protonation, the planar self-diffusion coefficient of Cs+ is always greater than that of Na+ ions. The results are useful for better understanding transport under confinement, including brine behavior in the subsurface, with important applications such as environmental remediation.

Ho, Tuan A. [University of Oklahoma, Norman; Argyris, D. [University of Oklahoma, Norman; Cole, David [Ohio State University; Striolo, Alberto [Oklahoma University

2011-01-01T23:59:59.000Z

294

Power scaling analysis of fiber lasers and amplifiers based on non-silica materials  

SciTech Connect (OSTI)

A developed formalism for analyzing the power scaling of diffraction limited fiber lasers and amplifiers is applied to a wider range of materials. Limits considered include thermal rupture, thermal lensing, melting of the core, stimulated Raman scattering, stimulated Brillouin scattering, optical damage, bend induced limits on core diameter and limits to coupling of pump diode light into the fiber. For conventional fiber lasers based upon silica, the single aperture, diffraction limited power limit was found to be 36.6kW. This is a hard upper limit that results from an interaction of the stimulated Raman scattering with thermal lensing. This result is dependent only upon physical constants of the material and is independent of the core diameter or fiber length. Other materials will have different results both in terms of ultimate power out and which of the many limits is the determining factor in the results. Materials considered include silica doped with Tm and Er, YAG and YAG based ceramics and Yb doped phosphate glass. Pros and cons of the various materials and their current state of development will be assessed. In particular the impact of excess background loss on laser efficiency is discussed.

Dawson, J W; Messerly, M J; Heebner, J E; Pax, P H; Sridharan, A K; Bullington, A L; Beach, R J; Siders, C W; Barty, C P; Dubinskii, M

2010-03-30T23:59:59.000Z

295

Study of a Threshold Cherenkov Counter Based on Silica Aerogels with Low Refractive Indices  

E-Print Network [OSTI]

To identify $\\pi^{\\pm}$ and $K^{\\pm}$ in the region of $1.0\\sim 2.5$ GeV/c, a threshold Cherenkov counter equipped with silica aerogels has been investigated. Silica aerogels with a low refractive index of 1.013 have been successfully produced using a new technique. By making use of these aerogels as radiators, we have constructed a Cherenkov counter and have checked its properties in a test beam. The obtained results have demonstrated that our aerogel was transparent enough to make up for loss of the Cherenkov photon yield due to a low refractive index. Various configurations for the photon collection system and some types of photomultipliers, such as the fine-mesh type, for a read out were also tested. From these studies, our design of a Cherenkov counter dedicated to $\\pi / K$ separation up to a few GeV/c %in the momentum range of $1.0 \\sim 2.5$ GeV/c with an efficiency greater than $90$ \\% was considered.

I. Adachi et al

1994-12-13T23:59:59.000Z

296

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

SciTech Connect (OSTI)

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.

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

1998-04-01T23:59:59.000Z

297

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

SciTech Connect (OSTI)

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.

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

1991-09-01T23:59:59.000Z

298

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

SciTech Connect (OSTI)

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.

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)

2014-09-07T23:59:59.000Z

299

The influence of pH over topography and spectroscopic properties of silica hybrid materials embedding meso-tetratolylporphyrin  

SciTech Connect (OSTI)

Hybrid porphyrin-silica materials consisting in 5,10,15,20-tetratolyl-21H,23H-porphine, encapsulated in silica matrices were obtained by sol-gel method. The hydrolysis and condensation reactions were performed by using tetraethylorthosilicate as precursor, either in one-step acid or in two steps acid-base catalysis, assisted or not by an ultrasonic field. The porphyrin-silica hybrid materials were monitored and characterized by AFM, FT-IR, fluorescence and UV-vis spectroscopy. As a result of porphyrin entrapping into silica gels, a general phenomenon regarding hyperchromic effects of the Q bands, occurs. UV-vis study revealed that during the sol-gel process, major changes regarding porphyrin ring structure occur, especially at acidic pH, when the dicationic species of porphyrin are formed. During acid-base catalyzed method the dye molecules tend to aggregate by {pi}-{pi} and hydrophobic co-facial interactions of sandwich H-type. In acid catalyzed process, the protonation of the porphyrins prevent the formation of aggregates, due to increased electrostatic repulsion between the molecules.

Fagadar-Cosma, Eugenia [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazul Avenue, No. 24, 300223 Timisoara (Romania)], E-mail: efagadar@yahoo.com; Enache, Corina; Armeanu, Ileana [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazul Avenue, No. 24, 300223 Timisoara (Romania); Dascalu, Dana [West University of Timisoara, Pestalozzi Street, No. 16, 300115 Timisoara (Romania); Fagadar-Cosma, Gheorghe ['Politehnica' University, T. Lalescu Street, No. 2, 300223 Timisoara (Romania); Vasile, Mihaela; Grozescu, Ioan [National Institute for Research and Development in Electrochemistry and Condensed Matter, P. Andronescu Street, No. 1, 300224 Timisoara (Romania)

2009-02-04T23:59:59.000Z

300

Reducing Logistics Footprints and Replenishment Demands: Nano-engineered Silica Aerogels a Proven Method for Water Treatment  

SciTech Connect (OSTI)

Rapid deployment and the use of objective force aggressively reduce logistic footprints and replenishment demands. Maneuver Sustainment requires that Future Combat Systems be equipped with water systems that are lightweight, have small footprints, and are highly adaptable to a variety of environments. Technologies employed in these settings must be able to meet these demands. Lawrence Livermore National Laboratory has designed and previously field tested nano-engineered materials for the treatment of water. These materials have been either based on silica aerogel materials or consist of composites of these aerogels with granular activated carbon (GAC). Recent tests have proven successful for the removal of contaminants including uranium, hexavalent chromium, and arsenic. Silica aerogels were evaluated for their ability to purify water that had been spiked with the nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate). These results demonstrated that silica aerogels were able to remove the VX from the supply water and were nearly 30 times more adsorbent than GAC. This performance could result in REDUCING CHANGEOUT FREQUENCY BY A FACTOR OF 30 or DECREASING the VOLUME of adsorbent BY A FACTOR OF 30; thereby significantly reducing logistic footprints and replenishment demands. The use of the nano-engineered Silica Aerogel/GAC composites would provide a water purification technology that meets the needs of Future Combat Systems.

Daily, W; Coleman, S; Love, A; Reynolds, J; O'Brien, K; Gammon, S

2004-09-22T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Hydrothermal Growth of Mesoporous SBA-15 Silica in the Presence of PVP-Stabilized Pt Nanoparticles: Synthesis,  

E-Print Network [OSTI]

Hydrothermal Growth of Mesoporous SBA-15 Silica in the Presence of PVP-Stabilized Pt Nanoparticles hydrothermal synthesis. Characterization of the Pt/SBA-15 catalysts suggests that Pt particles are located are responsible for ethane decomposition to surface carbon. The ability to design catalytic structures

Yang, Peidong

302

RADECS 2010 Proceedings Paper LN2 1 Abstract--Radiation effects in ytterbium-doped silica optical  

E-Print Network [OSTI]

fibers are still poorly studied despite their importance in space- based applications as optical inter measurements. Connections between traps populated by X ray irradiations and the radiation-induced optical Stimulated Luminescence, Ytterbium-doped silica optical fibers. I. INTRODUCTION HE radiation

Boyer, Edmond

303

Atomistic simulation of the interface structure of Si nanocrystals embedded in amorphous silica Flyura Djurabekova and Kai Nordlund*  

E-Print Network [OSTI]

Atomistic simulation of the interface structure of Si nanocrystals embedded in amorphous silica 11 February 2008; published 14 March 2008 An efficient means to obtain light emission from a silicon in industrial wafer manufacturing lines, this has opened up a promising avenue for using low-cost silicon chips

Nordlund, Kai

304

Replication of butterfly wing and natural lotus leaf nanostructures by nanoimprint on Silica Sol-gel films.  

E-Print Network [OSTI]

1 Replication of butterfly wing and natural lotus leaf nanostructures by nanoimprint on Silica Sol these biomimetics structures over large scales and at affordable price for industrial applications as for example have chosen to imprint the lotus leaf and butterfly wings in order to obtain superhydrophobic surfaces

305

Preparation of Catalytic Nanoparticles in Mesoporous Silica Film for Oriented Growth of Single-Walled Carbon Nanotubes  

E-Print Network [OSTI]

method at the dipping rate of 2 cm/min. After the coating, the piece was dried in air at 80 o C overnight is coated on the cobalt thin film deposited by sputtering. From these investigations, it is concluded silica film should have mesopores which run through the film from the substrate to the surface. Even

Maruyama, Shigeo

306

Fractal Analysis of Flame-Synthesized Nanostructured Silica and Titania Powders Using Small-Angle X-ray  

E-Print Network [OSTI]

Fractal Analysis of Flame-Synthesized Nanostructured Silica and Titania Powders Using Small-Angle X these powders display mass-fractal morphologies, which are composed of ramified aggregates of nanoscale primary particles. Primary particle size, aggregate size, fractal dimension, and specific surface area are obtained

Beaucage, Gregory

307

Journal of Molecular Catalysis A: Chemical 167 (2001) 191198 The nucleation and growth of gold on silica  

E-Print Network [OSTI]

on silica K. Luoa, D.Y. Kimb, D.W. Goodmana, a Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, TX 77842-3012, USA b Department of Chemistry, Hallym University, Seoul, South Korea.2 monolayer equivalents were determined by TPD to be significantly lower than the sublimation energies found

Goodman, Wayne

308

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

SciTech Connect (OSTI)

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}.

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

2010-02-23T23:59:59.000Z

309

Surface Complexation Model for Strontium Sorption to Amorphous Silica and Goethite  

SciTech Connect (OSTI)

Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25 C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr{sup 2+} and SrOH{sup +} complexes on the {beta}-plane and a monodentate Sr{sup 2+} complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH{sup +} complexes and a tetradentate binuclear Sr{sup 2+} species on the {beta}-plane. The binuclear complex is needed to account for enhanced sorption at high strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr{sup 2+} and SrOH{sup +} carbonate surface complexes on the {beta}-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis of extended X-ray absorption fine structure (EXAFS) on selected sorption samples that show a single first shell of oxygen atoms around strontium indicating hydrated surface complexes at the amorphous silica and goethite surfaces. Strontium surface complexation equilibrium constants determined in this study combined with other alkaline earth surface complexation constants are used to recalibrate a predictive model based on Born solvation and crystal-chemistry theory. The model is accurate to about 0.7 log K units. More studies are needed to determine the dependence of alkaline earth sorption on ionic strength and dissolved carbonate and sulfate concentrations for the development of a robust surface complexation database to estimate alkaline earth sorption in the environment.

Carroll, S; Robers, S; Criscenti, L; O'Day, P

2007-11-30T23:59:59.000Z

310

Photovoltaic's silica-rich waste sludge as supplementary cementitious material (SCM)  

SciTech Connect (OSTI)

Waste sludge, a solid recovered from wastewater of photovoltaic-industries, composes of agglomerates of nano-particles like SiO{sub 2} and CaCO{sub 3}. This sludge deflocculates in aqueous solutions into nano-particles smaller than 1 ?m. Thus, this sludge constitutes a potentially hazardous waste when it is improperly disposed. Due to its high content of amorphous SiO{sub 2}, this sludge has a potential use as supplementary cementitious material (SCM) in concrete. In this study the main properties of three different samples of photovoltaic's silica-rich waste sludge (nSS) were physically and chemically characterized. The characterization techniques included: scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), nitrogen physical adsorption isotherm (BET method), density by Helium pycnometry, particle size distribution determined by laser light scattering (LLS) and zeta-potential measurements by dynamic light scattering (DLS). In addition, a dispersability study was performed to design stable slurries to be used as liquid additives for the concrete production on site. The effects on the hydration kinetics of cement pastes by the incorporation of nSS in the designed slurries were determined using an isothermal calorimeter. A compressive strength test of standard mortars with 7% of cement replacement was performed to determine the pozzolanic activity of the waste nano-silica sludge. Finally, the hardened system was fully characterized to determine the phase composition. The results demonstrate that the nSS can be utilized as SCM to replace portion of cement in mortars, thereby decreasing the CO{sub 2} footprint and the environmental impact of concrete. -- Highlights: •Three different samples of PV nano-silica sludge (nSS) were fully characterized. •nSS is composed of agglomerates of nano-particles like SiO{sub 2} and CaCO{sub 3}. •Dispersability studies demonstrated that nSS agglomerates are broken to nano-size. •nSS can be classified as a pozzolanic material with activity index higher than 100. •nSS can be use as a potential SCM to partly replace cement in concrete.

Quercia, G., E-mail: g.quercia@tue.nl [Materials innovation institute (M2i), Mekelweg 2, P.O. Box 5008, 2600 GA Delft (Netherlands); Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Putten, J.J.G. van der [Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Hüsken, G. [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, D-12205 Berlin (Germany)] [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, D-12205 Berlin (Germany); Brouwers, H.J.H. [Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven (Netherlands)] [Eindhoven University of Technology, Department of the Built Environment, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2013-12-15T23:59:59.000Z

311

An evaluation of the geothermal potential of the Tecuamburro Volcano area of Guatemala  

SciTech Connect (OSTI)

Radiometric ages indicate that the Tecuamburro Volcano and three adjacent lava domes grew during the last 38,300 years, and that a 360-m-wide phreatic crater, Laguna Ixpaco, was formed near the base of these domes about 2900 years ago. Laguna Ixpaco is located within the Chupadero crater, from which pyroxene pumice deposits were erupted 38,300 years ago. Thus, the likelihood is great for a partly molten or solid-but-still-hot near-surface intrusion beneath the area. Fumaroles and hot springs issue locally from the Tecuamburro volcanic complex and near Laguna Ixpaco. Analyses of gas and fluid samples from these and other nearby thermal manifestations yield chemical-geothermometer temperatures of about 150{degree} to 300{degree}C, with the highest temperatures at Ixpaco. The existence of a commercial-grade geothermal reservoir beneath the Ixpaco area seems likely. 84 refs., 70 figs., 12 tabs.

Heiken, G.; Duffield, W. (eds.)

1990-09-01T23:59:59.000Z

312

Adsorption and methanation of carbon dioxide on a nickel/silica catalyst  

SciTech Connect (OSTI)

Temperature-programed desorption and reaction studies showed that increasing amounts of CO/sub 2/ adsorbed on silica-supported 6.9% nickel with increasing temperature to a maximum adsorption at approx. 443/sup 0/K, i.e., that the adsorption was activated; that CO/sub 2/ desorbed partly as CO/sub 2/ with the peak at 543/sup 0/K, and partly as CO with several peaks; that in the presence of hydrogen, nearly all adsorbed CO/sub 2/ desorbed as methane, and a small amount as CO; and that the methane desorption peaks from adsorbed CO and CO/sub 2/ both occurred at 473/sup 0/K. These results suggested that carbon dioxide adsorbed dissociatively as a carbon monoxide and an oxygen species. An observed absence of higher hydrocarbons in the methanation products of carbon dioxide was attributed to a high hydrogen/carbon monoxide surface ratio caused by the activated carbon dioxide adsorption.

Falconer, J.L.; Zagli, A.E.

1980-04-01T23:59:59.000Z

313

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

DOE Patents [OSTI]

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.

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

2004-03-16T23:59:59.000Z

314

Density hysteresis of heavy water confined in a nanoporous silica matrix  

SciTech Connect (OSTI)

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.

Zhang, Yang [ORNL; Faraone, Antonio [National Institute of Standards and Technology (NIST); Kamitakahara, William [ORNL; Liu, Kao-Hsiang [National Taiwan University; Mou, Chung-Yuan [National Taiwan University; Leao, Juscelino B [ORNL; Chang, Sung C [ORNL; Chen, Sow-hsin H [ORNL

2011-01-01T23:59:59.000Z

315

A molecular dynamics investigation of the unusual concentration dependencies of Fick diffusivities in silica mesopores  

SciTech Connect (OSTI)

Molecular Dynamics (MD) simulations were carried out to determine the self-diffusivitiy, D{sub i,self}, the Maxwell–Stefan diffusivity, Ð{sub i}, and the Fick diffusivity, D{sub i}, for methane (C1), ethane (C2), propane (C3), n-butane (nC4), n-pentane (nC5), n-hexane (nC6), n-heptane (nC7), and cyclohexane (cC6) in cylindrical silica mesopores for a range of pore concentrations. The MD simulations show that zero-loading diffusivity Ð{sub i}(0) is consistently lower, by up to a factor of 20, than the values anticipated by the classical Knudsen formula. The concentration dependence of the Fick diffusivity, D{sub i} is found to be unusually complex, and displays a strong minimum in some cases; this characteristic can be traced to molecular clustering.

Krishna, Rajamani; van Baten, Jasper M

2011-01-01T23:59:59.000Z

316

X-ray radiographic technique for measuring density uniformity of silica aerogel  

E-Print Network [OSTI]

This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n = 1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |\\delta (n - 1)/(n - 1)| aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within \\pm 1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.

Makoto Tabata; Yoshikiyo Hatakeyama; Ichiro Adachi; Takeshi Morita; Keiko Nishikawa

2012-12-14T23:59:59.000Z

317

Tanpopo cosmic dust collector: Silica aerogel production and bacterial DNA contamination analysis  

E-Print Network [OSTI]

Hydrophobic silica aerogels with ultra-low densities have been designed and developed as cosmic dust capture media for the Tanpopo mission which is proposed to be carried out on the International Space Station. Glass particles as a simulated cosmic dust with 30 \\mu m in diameter and 2.4 g/cm^3 in density were successfully captured by the novel aerogel at a velocity of 6 km/s. Background levels of contaminated DNA in the ultra-low density aerogel were lower than the detection limit of a polymerase chain reaction assay. These results show that the manufactured aerogel has good performance as a cosmic dust collector and sufficient quality in respect of DNA contamination. The aerogel is feasible for the biological analyses of captured cosmic dust particles in the astrobiological studies.

Tabata, Makoto; Yokobori, Shin-ichi; Kawai, Hideyuki; Takahashi, Jun-ichi; Yano, Hajime; Yamagishi, Akihiko

2011-01-01T23:59:59.000Z

318

Development of transparent silica aerogel over a wide range of densities  

E-Print Network [OSTI]

We have succeeded in developing hydrophobic silica aerogels over a wide range of densities (i.e. refractive indices). A pinhole drying method was invented to make possible producing highly transparent aerogels with entirely new region of refractive indices of 1.06-1.26. Obtained aerogels are more transparent than conventional ones, and the refractive index is well controlled in the pinhole drying process. A test beam experiment was carried out in order to evaluate the performance of the pinhole-dried aerogels as a Cherenkov radiator. A clear Cherenkov ring was successfully observed by a ring imaging Cherenkov counter. We also developed monolithic and hydrophobic aerogels with a density of 0.01 g/cm^3 (a low refractive index of 1.0026) as a cosmic dust capturer for the first time. Consequently, aerogels with any refractive indices between 1.0026 and 1.26 can be produced freely.

Tabata, Makoto; Ishii, Yoshikazu; Kawai, Hideyuki; Sumiyoshi, Takayuki; Yokogawa, Hiroshi; 10.1016/j.nima.2010.02.241

2011-01-01T23:59:59.000Z

319

Development of transparent silica aerogel over a wide range of densities  

E-Print Network [OSTI]

We have succeeded in developing hydrophobic silica aerogels over a wide range of densities (i.e. refractive indices). A pinhole drying method was invented to make possible producing highly transparent aerogels with entirely new region of refractive indices of 1.06-1.26. Obtained aerogels are more transparent than conventional ones, and the refractive index is well controlled in the pinhole drying process. A test beam experiment was carried out in order to evaluate the performance of the pinhole-dried aerogels as a Cherenkov radiator. A clear Cherenkov ring was successfully observed by a ring imaging Cherenkov counter. We also developed monolithic and hydrophobic aerogels with a density of 0.01 g/cm^3 (a low refractive index of 1.0026) as a cosmic dust capturer for the first time. Consequently, aerogels with any refractive indices between 1.0026 and 1.26 can be produced freely.

Makoto Tabata; Ichiro Adachi; Yoshikazu Ishii; Hideyuki Kawai; Takayuki Sumiyoshi; Hiroshi Yokogawa

2011-12-21T23:59:59.000Z

320

X-ray radiographic technique for measuring density uniformity of silica aerogel  

E-Print Network [OSTI]

This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n = 1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |\\delta (n - 1)/(n - 1)| aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within \\pm 1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.

Tabata, Makoto; Adachi, Ichiro; Morita, Takeshi; Nishikawa, Keiko; 10.1016/j.nima.2012.09.001

2012-01-01T23:59:59.000Z

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321

Liquid–solid phase transition of hydrogen and deuterium in silica aerogel  

SciTech Connect (OSTI)

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 liquid–solid 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.

Van Cleve, E.; Worsley, M. A.; Kucheyev, S. O., E-mail: kucheyev@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2014-10-28T23:59:59.000Z

322

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

SciTech Connect (OSTI)

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.

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

1991-09-01T23:59:59.000Z

323

Post-Harvest Processing Methods for Reduction of Silica and Alkali Metals in Wheat Straw  

SciTech Connect (OSTI)

Silica and alkali metals in wheat straw limit its use for bioenergy and gasification. Slag deposits occur via the eutectic melting of SiO2 with K2O, trapping chlorides at surfaces and causing corrosion. A minimum melting point of 950°C is desirable, corresponding to SiO2:K2O of about 3:1. Mild chemical treatments were used to reduce Si, K, and Cl, while varying temperature, concentration, %-solids, and time. Dilute acid was more effective at removing K and Cl, while dilute alkali was more effective for Si. Reduction of minerals in this manner may prove economical for increasing utilization of the straw for combustion or gasification.

Thompson, David Neal; Lacey, Jeffrey Alan; Shaw, Peter Gordon

2002-04-01T23:59:59.000Z

324

Phototransformation of Polycyclic Aromatic Hydrocarbons (PAHs) on a Non-Semi Conductive Surface Such as Silica  

SciTech Connect (OSTI)

Polycyclic aromatic hydrocarbons (PAH), by products of fossil fuel production and consumption, constitute a large class of environmental pollutants. These toxic and sometimes carcinogenic compounds are also found in coal tar and fly ash. When released into the air, they can be sorbed onto particulates present in the atmosphere where they find their way into soil and ground water upon being washed by rain. During their residence time in the environment, PAHs will be exposed to solar radiation and may undergo phototransformation to other products. Thus, light induced photodegradation of PM`s at the solid/air interfaces can play a significant role in their depletion. Light-induced processes have been claimed to enhance transformation of these PM`s in the environment. However, detailed studies on the nature and identities of photoproducts formed during the transformation of these compounds on solid surfaces is scarce. Since insulators such as silica, alumina,silicoaluminates and calcium carbonate are believed to constitute up 20-30% of inorganic particulates present in the atmosphere, they serve as environmentally relevant model surfaces to study the photophysical and photochemical behavior of PM`s. Although photochemistry of organic compounds adsorbed on solid surfaces has received much attention in recent years, the specific properties of the interface which influence photoprocesses and the exact mechanism of interaction between a surface and a substrate are often not well understood. We have investigated the photochemistry of many PAHs including eight that are on Environmental Protection Agency`s (EPA) sixteen priority pollutant PAH list shown in Table 1 at silica/air interface.

Dabestani, R., Sigman, M.E.

1997-09-16T23:59:59.000Z

325

Robust conductive mesoporous carbon?silica composite films with highly ordered and oriented orthorhombic structures from triblock-copolymer template co-assembly  

SciTech Connect (OSTI)

In this work, we describe a facile approach to improve the robustness of conductive mesoporous carbon-based thin films by the addition of silica to the matrix through the triconstituent organic-inorganic-organic co-assembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock-copolymer Pluronic F127. The pyrolysis of the resol-silica-pluronic F127 film yields a porous composite thin film with well-defined mesostructure. X-Ray diffraction (XRD), grazing incidence small angle X-ray scattering (GISAXS), and electron microscopy measurements indicate that the obtained carbon-based thin films have a highly ordered orthorhombic mesostructure (Fmmm) with uniform large pore size ({approx}3 nm). The orthorhombic mesostructure is oriented and the (010) plane is parallel to the silicon wafer substrate. The addition of silica to the matrix impacts the pore size, surface area, porosity, modulus and conductivity. For composite films with approximately 40 wt% silica, the conductivity is decreased by approximately an order of magnitude in comparison to a pure carbon mesoporous film, but the conductivity is comparable to typical printed carbon inks used in electrochemical sensing, {approx}10 S cm{sup -1}. The mechanical properties of these mesoporous silica-carbon hybrid films are similar to the pure carbon analogs with a Young's modulus between 10 GPa and 15 GPa, but the material is significantly more porous. Moreover, the addition of silica to the matrix appears to improve the adhesion of the mesoporous film to a silicon wafer. These mesoporous silica-carbon composite films have appropriate characteristics for use in sensing applications.

Song, Lingyan; Feng, Dan; Campbell, Casey G.; Gu, Dong; Forster, Aaron M.; Yager, Kevin G.; Fredin, Nathaniel; Lee, Hae-Jeong; Jones, Ronald L.; Zhao, Dongyuan; Vogt, Bryan D. (AZU)

2012-07-11T23:59:59.000Z

326

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

SciTech Connect (OSTI)

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.

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

2013-08-05T23:59:59.000Z

327

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

SciTech Connect (OSTI)

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.)

Kuila, Debasish; Ilias, Shamsuddin

2013-02-13T23:59:59.000Z

328

Differences in pulmonary responses of rats, other animals, and humans to chronic inhalation of silica and other particles  

SciTech Connect (OSTI)

The pulmonary carcinogenicity of quartz in rats supports the plausibility of silica-induced lung cancer in humans. However, pulmonary responses of rats to dusts differ from those of other rodents, and may differ from those of humans. Dust-exposed rats have a greater propensity than mice or hamsters for epithelial hyperplasia, metaplasia, and fibrosis. Lung tumors occur in rats, but not mice or hamsters, treated with quartz, or exposed chronically to several other dusts. There are few opportunities for directly comparing the susceptibilities of rats and humans to dust-induced lung tumors. Because of the uncertain human responses to silica and many other particles, the negative human lung cancer response to coal dust may provide the best opportunity to calibrate responses of rats against those of humans. Historical dust lung burdens in coal miners were in the range of those associated with carcinogenicity in rats exposed to several dusts, but the carcinogenicity of coal dust in rats is unknown. The usefulness of tumor data from rats for predicting human lung cancer risk from inhaled silica and other dusts remains uncertain.

Mauderly, J.L.

1993-12-31T23:59:59.000Z

329

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

SciTech Connect (OSTI)

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.

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

2008-10-30T23:59:59.000Z

330

Adsorption and methanation of carbon dioxide on a nickel/silica catalyst  

SciTech Connect (OSTI)

The adsorption and methanation of carbon dioxide on a nickel/silica catalyst were studied using temperature-programmed desorption and temperature-programmed reaction. Carbon dioxide adsorption on nickel was found to be activated; almost no adsorption occurred at room temperature, but large coverages were obtained between 383 and 473 K. The data indicate CO/sub 2/ dissociates upon adsorption at elevated temperatures to yield carbon monoxide and oxygen atoms. These oxygen atoms react with hydrogen at room temperature, so the methane and water observed during programmed heating in flowing hydrogen are identical for adsorbed CO and adsorbed CO/sub 2/. Single CH/sub 4/ and H/sub 2/O peaks, each with a peak temperature at 473 K, were observed. This peak temperature did not change with initial coverage, indicating methanation is first order in CO surface coverage. The activated adsorption of CO/sub 2/ allowed these coverage variation experiments to be carried out. Thus, following adsorption, CO and CO/sub 2/ methanation proceed by the same mechanism. However, the activated adsorption of CO/sub 2/ may create a higher H/sub 2/:CO surface ratio during steady-state hydrogenation, causing CO/sub 2/ hydrogenation to favor methane over higher hydrocarbons. 5 figures.

Falconer, J.L.; Zagli, A.E.

1980-04-01T23:59:59.000Z

331

Morphologies of laser-induced damage in hafnia-silica multilayer mirror and polarizer coatings  

SciTech Connect (OSTI)

Hafnium-silica multilayer mirrors and polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The mirrors and polarizers were coated for operation at 1053 nm at 45{degree} and at Brewster`s angle (56{degree}), respectively. They were tested with a single 3-ns laser pulse. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies were found: pits, flatbottom pits, scalds, and delaminates. The pits and flat bottom pits (<30{mu}m dia) were detected at lower fluences (as low as 5 J/cm{sup 2}). The pits seemed to result from ejection of nodular defects by causing local enhancement of the electric field. Scalds and delaminates could be observed at higher fluences (above 13 J/cm{sup 2}) and seemed to result from the formation of plasmas on the surface. These damage types often originated at pits and were less than 300 {mu}m diameter; their size increased almost linearly with fluence. Finally, effects of the damage on the beam (reflectivity degradation and phase modulations) were measured.

Genin, F.Y.; Stolz, C.J.

1996-08-01T23:59:59.000Z

332

A New Concept for the Fabrication of Hydrogen Selective Silica Membranes  

SciTech Connect (OSTI)

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.

Michael Tsapatsis

2005-10-01T23:59:59.000Z

333

Helium adsorption in silica aerogel near the liquid-vapor critical point  

E-Print Network [OSTI]

We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95% and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel's very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales.

Tobias Herman; James Day; John Beamish

2005-05-18T23:59:59.000Z

334

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

SciTech Connect (OSTI)

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}.

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

2007-03-02T23:59:59.000Z

335

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

SciTech Connect (OSTI)

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.

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

2011-11-16T23:59:59.000Z

336

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

SciTech Connect (OSTI)

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.

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

2014-01-01T23:59:59.000Z

337

The effect of particle-particle interaction forces on the flow properties of silica slurries  

SciTech Connect (OSTI)

Preliminary work has been completed to investigate the effect of particle-particle interaction forces on the flow properties of silica slurries. Classically hydro-transport studies have focused on the flow of coarse granular material in Newtonian fluids. However, with current economical and environmental pressures, the need to increase solid loadings in pipe flow has lead to studies that examine non-Newtonian fluid dynamics. The flow characteristics of non-Newtonian slurries can be greatly influenced through controlling the solution chemistry. Here we present data on an 'ideal' slurry where the particle size and shape is controlled together with the solution chemistry. We have investigated the effect of adsorbed cations on the stability of a suspension, the packing nature of a sediment and the frictional forces to be overcome during re-slurrying. A significant change in the criteria assessed was observed as the electrolyte concentration was increased from 0.1 mM to 1 M. In relation to industrial processes, such delicate control of the slurry chemistry can greatly influence the optimum operating conditions of non-Newtonian pipe flows. (authors)

Harbottle, David; Fairweather, Michael; Biggs, Simon [Institute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, UK, LS2 9JT (United Kingdom); Rhodes, Dominic [Nexia Solutions, Sellafield, Cumbria (United Kingdom)

2007-07-01T23:59:59.000Z

338

Helium Adsorption in Silica Aerogel near the Liquid-Vapor Critical Point  

E-Print Network [OSTI]

We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95 % and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel’s very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales. I.

Tobias Herman; James Day; John Beamish

2008-01-01T23:59:59.000Z

339

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

SciTech Connect (OSTI)

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.

Price, C.W.

1988-01-01T23:59:59.000Z

340

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

SciTech Connect (OSTI)

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.

Lebugle, M., E-mail: lebugle@lp3.univ-mrs.fr; Sanner, N.; Varkentina, N.; Sentis, M.; Utéza, O. [Aix Marseille Université, CNRS, LP3 UMR 7341, 13288 Marseille (France)

2014-08-14T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


341

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

SciTech Connect (OSTI)

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.

Pinto, S. R. C.; Ramos, M. M. D.; Gomes, M. J. M. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Buljan, M. [Ruder Boskovic Institute, Bijenicka cesta 54, Zagreb 10000 (Croatia); Chahboun, A. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Physics Department, FST Tanger, Tanger BP 416 (Morocco); Roldan, M. A.; Molina, S. I. [Departamento de Ciencia de los Materiales e Ing. Metalurgica y Q. I., Universidad de Cadiz, Cadiz (Spain); Bernstorff, S. [Sincrotrone Trieste, SS 14 km163, 5, Basovizza 34012 (Italy); Varela, M.; Pennycook, S. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Barradas, N. P.; Alves, E. [Instituto Superior Tecnico e Instituto Tecnologico e Nuclear-, EN10, Sacavem 2686-953 (Portugal)

2012-04-01T23:59:59.000Z

342

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

SciTech Connect (OSTI)

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.

Pinto, S. [University of Minho, Portugal; Roldan Gutierrez, Manuel A [ORNL; Ramos, M. M.D. [University of Minho, Portugal; Gomes, M.J.M. [University of Minho, Portugal; Molina, S. I. [Universidad de Cadiz, Spain; Pennycook, Stephen J [ORNL; Varela del Arco, Maria [ORNL; Buljan, M. [R. Boskovic Institute, Zagreb, Croatia; Barradas, N. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Alves, E. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Chahboun, A. [FST Tanger, Morocco; Bernstorff, S. [Sincrotrone Trieste, Basovizza, Italy

2012-01-01T23:59:59.000Z

343

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

SciTech Connect (OSTI)

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.

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

2008-01-01T23:59:59.000Z

344

Comparisons between laser damage and optical electric field behaviors for hafnia/silica antireflection coatings  

SciTech Connect (OSTI)

We compare designs and laser-induced damage thresholds (LIDTs) of hafnia/silica antireflection (AR) coatings for 1054 nm or dual 527 nm/1054 nm wavelengths and 0 deg. to 45 deg. angles of incidence (AOIs). For a 527 nm/1054 nm, 0 deg. AOI AR coating, LIDTs from three runs arbitrarily selected over three years are {approx}20 J/cm{sup 2} or higher at 1054 nm and <10 J/cm{sup 2} at 527 nm. Calculated optical electric field intensities within the coating show two intensity peaks for 527 nm but not for 1054 nm, correlating with the lower (higher) LIDTs at 527 nm (1054 nm). For 1054 nm AR coatings at 45 deg. and 32 deg. AOIs and S and P polarizations (Spol and Ppol), LIDTs are high for Spol (>35 J/cm{sup 2}) but not as high for Ppol (>30 J/cm{sup 2} at 32 deg. AOI; {approx}15 J/cm{sup 2} at 45 deg. AOI). Field intensities show that Ppol discontinuities at media interfaces correlate with the lower Ppol LIDTs at these AOIs. For Side 1 and Side 2 dual 527 nm/1054 nm AR coatings of a diagnostic beam splitter at 22.5 deg. AOI, Spol and Ppol LIDTs (>10 J/cm{sup 2} at 527 nm; >35 J/cm{sup 2} at 1054 nm) are consistent with Spol and Ppol intensity behaviors.

Bellum, John; Kletecka, Damon; Rambo, Patrick; Smith, Ian; Schwarz, Jens; Atherton, Briggs

2011-03-20T23:59:59.000Z

345

Luminescence of silicon dioxide different polymorph modification: Silica glass, ?-quartz, stishovite, coesite  

SciTech Connect (OSTI)

Stishovite, coesite, oxygen deficient silica glass as well as irradiated ?-quartz, exhibit two luminescence bands: a blue one and an UV one both excitable in the range within optical gap. There are similarities in spectral position and in luminescence decay kinetics among centers in these materials. The interpretation was done on the model of Oxygen Deficient Centers (ODC) [1]. The ODC(II) or twofold coordinated silicon and ODC(I) are distinguished. ODC(I) is object of controversial interpretation. The Si-Si oxygen vacancy [2] and complex defect including latent twofold coordinated silicon [3] are proposed. Remarkably, this luminescence center does not exist in as grown crystalline ?-quartz. However, destructive irradiation of ?-quartz crystals with fast neutrons, ? rays, or dense electron beams [4–6] creates ODC(I) like defect. In tetrahedron structured coesite the self trapped exciton (STE) luminescence observed with high energetic yield (?30%) like in ?-quartz crystals. STE in coesite coexists with oxygen deficient-like center. In octahedron structured stishovite STE was not found and only ODC exists.

Trukhin, A. N., E-mail: truhins@cfi.lu.lv [Institute of Solid State Physics, University of Latvia, LV-1063 Riga (Latvia)

2014-10-21T23:59:59.000Z

346

Rapid Extraction of Dust Impact Tracks from Silica Aerogel by Ultrasonic Micro-blades  

SciTech Connect (OSTI)

In January 2006, NASA's Stardust Mission will return with its valuable cargo of cometary dust particles, the first brought back to Earth, captured at hypervelocity speeds in silica aerogel collectors. Aerogel, a proven capture medium, is also a candidate for future sample return missions and low-earth orbit (LEO) deployments. Critical to the science return of Stardust and future missions using aerogel is the ability to efficiently extract impacted particles from collector tiles. Researchers will be eager to obtain Stardust samples as quickly as possible, and tools for the rapid extraction of particle impact tracks that require little construction, training, or investment would be an attractive asset. To this end, we have experimented with diamond and steel micro-blades. Applying ultrasonic frequency oscillations to these micro-blades via a piezo-driven holder produces rapid, clean cuts in the aerogel with minimal damage to the surrounding collector tile. With this approach, impact tracks in aerogel fragments with low-roughness cut surfaces have been extracted from aerogel tiles flown on NASA's Orbital Debris Collector Experiment. The smooth surfaces produced during cutting reduce imaging artifacts during analysis by SEM. Some tracks have been dissected to expose the main cavity for eventual isolation of individual impact debris particles and further analysis by techniques such as TEM and nanoSIMS.

Ishii, H; Graham, G; Kearsley, A T; Grant, P G; Snead, C J; Bradley, J P

2005-02-17T23:59:59.000Z

347

Nano-Structured Mesoporous Silica Wires with Intra-Wire Lamellae via Evaporation-Induced Self-Assembly in Space-Confined Channels  

SciTech Connect (OSTI)

Evaporation-induced self-assembly (EISA) of silica sol-gel ethanol-water solution mixtures with block-copolymer were studied inside uniform micro/nano channels. Nano-structured mesoporous silica wires, with various intra-wire self-assembly structures including lamellae, were prepared via EISA process but in space-confined channels with the diameter ranging from 50 nm to 200 nm. Membranes made of anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC) were utilized as the arrays of space-confined channels (i.e., 50, 100, and 200-nm EPC and 200-nm AAO) for infiltration and drying of mixture solutions; these substrate membranes were submerged in mixture solutions consisting of a silica precursor, a structure-directing agent, ethanol, and water. After the substrate channels were filled with the solution under vacuum impregnation, the membrane was removed from the solution and dried in air. The silica precursor used was tetra-ethyl othosilicate (TEOS), and the structure-directing agent employed was triblock copolymer Pluronic-123 (P123). It was found that the formation of the mesoporous nanostructures in silica wires within uniform channels were significantly affected by the synthesis conditions including (1) pre-assemble TEOS aging time, (2) the evaporation rate during the vacuum impregnation, and (3) the air-dry temperature. The obtained intra-wire structures, including 2D-hexagonal rods and lamellae, were studied by scanning transmission electron microscopy (STEM). A steric hindrance effect seems to explain well the observed polymer-silica mesophase formation tailored by TEOS aging time. The evaporation effect, air-drying effect, and AAO-vs-EPC substrate effect on the mesoporous structure of the formed silica wires were also presented and discussed.

Hu, Michael Z. [ORNL; Shi, Donglu [University of Cincinnati; Blom, Douglas Allen [ORNL

2014-01-01T23:59:59.000Z

348

Intraparticle heat and mass transfer characteristics of silica-gel/water vapor adsorption  

SciTech Connect (OSTI)

Recently, highly efficient energy utilization systems which extensively employ adsorption phenomena such as pressure swing adsorption, heat storage, adsorption heat pump, etc. are being regarded as one of the countermeasures for environmental issues such as green house effect and ozone layer destruction. An Adsorption Heat Pump (AHP) has been investigated as one of the important techniques via which cold heat energy is obtained from waste thermal energy below 373K without using electricity and CFCs. An AHP normally consists of an adsorber and an evaporator/condenser and cold heat energy is generated by latent heat of evaporation during adsorption process. For realizing the AHP technology, it has been pointed out that the development of an adsorber with optimum heat and mass transfer characteristics is essentially important. In this study, experimental studies were carried out which was based on the data of temperature inside the adsorbent particle and adsorptivity profiles at the adsorption/desorption process by volumetric method. To clarify adsorption mechanism relatively large silica-gel particle (7 mm f) was used. Temperature distribution in the particle is determined at the center, at one half radius in the radial direction and at the surface by using very thin (30 mm f) thermocouples. The temperatures at these points simultaneously increase/decrease as soon as the adsorption/desorption started, reached their respective maximum/minimum values and then return to initial temperature. The temperature profiles for the adsorption process show that the temperature at the surface is initially slightly higher than the other two points. All three points reached their respective maximum temperature at the same time with the temperature at the center point the highest and at the surface the lowest. The temperature profiles during the desorptive process are almost exactly the opposite to that of the adsorption process. This shows that the adsorption phenomena can take place not only at the surface but inside the adsorbent particle, implying that intraparticle vapor diffusion has a great influence on adsorptivity.

Yamamoto, Eri; Watanabe, Fujio; Hasatani, Masanobu

1999-07-01T23:59:59.000Z

349

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

SciTech Connect (OSTI)

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), UV–vis spectroscopy, inductively coupled plasma (ICP) and N{sub 2} adsorption–desorption 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.

Tadjarodi, Azadeh, E-mail: tajarodi@iust.ac.ir [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of); Zabihi, Fatemeh [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of); Chemistry and Nanotechnology Laboratory, National Center for Laser Science and Technology, Tehran (Iran, Islamic Republic of)

2013-10-15T23:59:59.000Z

350

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

SciTech Connect (OSTI)

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 14–16?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 4–400?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 200–440?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.

Savchenko, D. V., E-mail: dariyasavchenko@gmail.com [Institute of Physics AS CR, Prague 182 21 (Czech Republic); V.E. Lashkaryov Institute of Semiconductor Physics, NASU, Kyiv 03028 (Ukraine); Shanina, B. D.; Kalabukhova, E. N.; Sitnikov, A. A.; Lysenko, V. S. [V.E. Lashkaryov Institute of Semiconductor Physics, NASU, Kyiv 03028 (Ukraine); Tertykh, V. A. [A.A. Chuiko Institute of Surface Chemistry, NASU, Kyiv 03164 (Ukraine)

2014-04-07T23:59:59.000Z

351

Imaging the early material response associated with exit surface damage in fused silica  

SciTech Connect (OSTI)

The processes involved at the onset of damage initiation on the surface of fused silica have been a topic of extensive discussion and thought for more than four decades. Limited experimental results have helped develop models covering specific aspects of the process. In this work we present the results of an experimental study aiming at imaging the material response from the onset of the observation of material modification during exposure to the laser pulse through the time point at which material ejection begins. The system involves damage initiation using a 355 nm pulse, 7.8 ns FWHM in duration and imaging of the affected material volume with spatial resolution on the order of 1 {micro}m using as strobe light a 150 ps laser pulse that is appropriately timed with respect to the pump pulse. The observations reveal that the onset of material modification is associated with regions of increased absorption, i.e., formation of an electronic excitation, leading to a reduction in the probe transmission to only a few percent within a time interval of about 1 ns. This area is subsequently rapidly expanding with a speed of about 1.2 {micro}m/ns and is accompanied by the formation and propagation of radial cracks. These cracks appear to initiate about 2 ns after the start of the expansion of the modified region. The damage sites continue to grow for about 25 ns but the mechanism of expansion after the termination of the laser pulse is via formation and propagation of lateral cracks. During this time, the affected area of the surface appears to expand forming a bulge of about 40 {micro}m in height. The first clear observation of material cluster ejection is noted at about 50 ns delay.

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

2010-11-05T23:59:59.000Z

352

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

SciTech Connect (OSTI)

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.

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

2009-11-02T23:59:59.000Z

353

Infrared thermometry and interferential microscopy for analysis of crater formation at the surface of fused silica under CO{sub 2} laser irradiation  

SciTech Connect (OSTI)

In situ spatial and temporal temperature measurements of a fused silica surface heated by a 10.6 {mu}m CO{sub 2} laser were performed using an infrared camera. These measurements were derived from heat flux emission of the fused silica. High temperature measurements--in the range 400-2500 K--were performed at the surface of a semi-transparent media with a high spatial resolution. Particular attention was given to the experimental conception and to the calibration of the infrared device. Moreover, both conventional and interferential microscopes were used to characterize the silica surfaces after CO{sub 2} laser irradiation. By associating these results with thermal camera measurements we identified the major surface temperature levels of silica transformation when heated during 250 ms. Surface deformation of silica is observed for temperatures <2000 K. This is consistent with other recent work using CO{sub 2} laser heating. At higher temperatures, matter ejection, as deduced from microscope observations, occurs at temperatures that are still much lower than the standard boiling point. Such evaporation is described by a thermodynamical approach, and calculations show very good agreement with experiment.

Robin, Lucile; Cormont, Philippe; Hebert, David; Mainfray, Christelle; Rullier, Jean-Luc [CEA Cesta, Le Barp, F-33114 France (France); Combis, Patrick [CEA DAM Ile-de-France, Arpajon Cedex, 91297 France (France); Gallais, Laurent [Institut Fresnel, CNRS, Aix-Marseille Universite, Ecole Centrale Marseille, Marseille, 13013 France (France)

2012-03-15T23:59:59.000Z

354

Recent progress in the development of large area silica aerogel for use as RICH radiator in the Belle II experiment  

E-Print Network [OSTI]

We report recent progress in the development of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter to be installed in the forward end cap of the Belle II detector, which is currently being upgraded at the High Energy Accelerator Research Organization (KEK), Japan. The production of approximately 450 aerogel tiles with refractive indices of either 1.045 or 1.055 was completed in May, 2014, and the tiles are now undergoing optical characterization. Installation of the aerogels was tested by installing them into a partial mock-up of the support structure.

Makoto Tabata; Ichiro Adachi; Hideyuki Kawai; Shohei Nishida; Takayuki Sumiyoshi

2014-11-16T23:59:59.000Z

355

Recent progress in the development of large area silica aerogel for use as RICH radiator in the Belle II experiment  

E-Print Network [OSTI]

We report recent progress in the development of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter to be installed in the forward end cap of the Belle II detector, which is currently being upgraded at the High Energy Accelerator Research Organization (KEK), Japan. The production of approximately 450 aerogel tiles with refractive indices of either 1.045 or 1.055 was completed in May, 2014, and the tiles are now undergoing optical characterization. Installation of the aerogels was tested by installing them into a partial mock-up of the support structure.

Tabata, Makoto; Kawai, Hideyuki; Nishida, Shohei; Sumiyoshi, Takayuki

2014-01-01T23:59:59.000Z

356

Field Trip Guide to Serpentinite, Silica-Carbonate Alteration, and Related Hydrothermal Activity in the Clear Lake Region, California  

SciTech Connect (OSTI)

This guide is designed to familiarize scientists with the geology, structure, alteration, and fluids typical of California serpentinites for purposes of carbon dioxide sequestration (Lackner et al., 1995). Goff et al. (1997) and Goff and Lackner (1998) describe the geology and geochemistry of some of the serpentinites from this area. Mechanisms of silica-carbonate alteration were outlined by Barnes et al. (1973). Donnelly-Nolan et al. (1993) most recently reviewed relations between regional hydrothermal alteration and Quarternary volcanic activity. Stanley et al. (1998) summarized geophysical characteristics of the region.

Fraser Goff; George Guthrie

1999-06-01T23:59:59.000Z

357

In-situ monitoring of surface post-processing in large aperture fused silica optics with Optical Coherence Tomography  

SciTech Connect (OSTI)

Optical Coherence Tomography is explored as a method to image laser-damage sites located on the surface of large aperture fused silica optics during post-processing via CO{sub 2} laser ablation. The signal analysis for image acquisition was adapted to meet the sensitivity requirements for this application. A long-working distance geometry was employed to allow imaging through the opposite surface of the 5-cm thick optic. The experimental results demonstrate the potential of OCT for remote monitoring of transparent material processing applications.

Guss, G M; Bass, I l; Hackel, R P; Mailhiot, C; Demos, S G

2008-02-08T23:59:59.000Z

358

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)

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.

KUTZMAN,R.S.

1984-02-01T23:59:59.000Z

359

Time-resolved measurement of photon emission during fast crack propagation in three-point bending fracture of silica glass and soda lime glass  

SciTech Connect (OSTI)

Simultaneous time-resolved measurements of photon emission (PE) and fast crack propagation upon bending fracture were conducted in silica glass and soda lime glass. Observation of fracture surfaces revealed that macroscopic crack propagation behavior was similar between the silica glass and soda lime glass when fracture loads for these specimens were comparable and cracks propagated without branching. However, a large difference in the PE characteristics was found between the two glasses. In silica glass, PE (645–655?nm) was observed during the entire crack propagation process, whereas intense PE (430–490?nm and 500–600?nm) was observed during the initial stages of propagation. In contrast, only weak PE was detected in soda lime glass. These results show that there is a large difference in the atomic processes involved in fast crack propagation between these glasses, and that PE can be used to study brittle fracture on the atomic scale.

Shiota, Tadashi, E-mail: tshiota@ceram.titech.ac.jp; Sato, Yoshitaka; Yasuda, Kouichi [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1-S7-13 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)] [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1-S7-13 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

2014-03-10T23:59:59.000Z

360

Compressive Creep Performance and High Temperature Dimensional Stability of Conventional Silica Refractories  

SciTech Connect (OSTI)

Furnace designers and refractory engineers recognize that optimized furnace superstructure design and refractory selection are needed as glass production furnaces are continually striving toward greater output and efficiencies. Harsher operating conditions test refractories to the limit, while changing production technology (such as the conversion to oxy-fuel from traditional air-fuel firing) can alter the way the materials perform. Refractories for both oxy- and air-fuel fired furnace superstructures are subjected to high temperatures during service that may cause them to excessively creep or subside if the refractory material is not creep resistant, or if it is subjected to high stress, or both. Furnace designers can ensure that superstructure structural integrity is maintained if the creep behavior of the refractory material is well understood and well represented by appropriate engineering creep models. Several issues limit the abilities of furnace designers to (1) choose the optimum refractory for their applications, (2) optimize the engineering design, or (3) predict the service mechanical integrity of their furnace superstructures. Published engineering creep data are essentially non-existent for almost all commercially available refractories used for glass furnace superstructures. The limited data that do exist are supplied by the various refractory suppliers. Unfortunately, these suppliers generally have different ways of conducting their mechanical testing and they also interpret and report their data differently; this makes it hard for furnace designers to draw fair comparisons between competing grades of candidate refractories. Furthermore, the refractory supplier's data are often not available in a form that can be readily used for furnace design and for the prediction and design of long-term structural integrity of furnace superstructures. With the aim of providing such comparable data, the US DOE's Office of Industrial Technology and its Advanced Industrial Materials program is sponsoring work to conduct creep testing and analysis on refractories of interest to the glass industry. An earlier stage of the project involved identifying which refractories to test and this is described elsewhere. Conventional silica was one such identified refractory category, and the present report describes the creep behavior of this class of refractories. To portray a more complete understanding of how these refractories perform at service temperatures, their fundamental corrosion resistances, dimensional stabilities, and microstructure were characterized as well.

Karakus, M.; Kirkland, T.P.; Liu, K.C.; Moore, R.E.; Pint, B.A.; Wereszczak, A.A.

1999-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
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We encourage you to perform a real-time search of NLEBeta
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361

Comprehensive Study of the Impact of Steam on Polyethyleneimine on Silica for CO{sub 2} Capture  

SciTech Connect (OSTI)

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 of 90 vol.% H{sub 2}O/He at 105 {degrees}?C and the gas effluent was monitored with a mass spectrometer. CO{sub 2} uptake of sorbent was found to decrease with repeated exposure to steam. Characterization of the spent sorbent using N{sub 2} physisorption, SEM, and thermogravimetric analysis (TGA), showed that the decrease in CO{sub 2} loading can possibly be attributed to a reagglomeration of the amine in the pores of the silica. No support effect was found in this study. The commercial SiO{sub 2} used, Cariact G10, was found to be stable under the conditions used. While it was found that subjecting the sorbent to several steam cycles decreased its CO{sub 2} uptake, a continuous exposure of the sorbent to steam did not have a significant performance impact. A silanated sorbent, consisting of a mixture of PEI and aminopropyl-triethoxysilane on SiO{sub 2} support, was also investigated for steam stability. Similarly to the non-silanated sorbent, the CO{sub 2} loading of this sorbent decreased upon steam exposure, although a mechanism for this change has not been postulated at this time.

Hammache, Sonia; Hoffman, James S.; Gray, McMahan L.; Fauth, Daniel J; Howard, Bret H.; Pennline, Henry W.

2013-11-01T23:59:59.000Z

362

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

SciTech Connect (OSTI)

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.

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

2013-09-02T23:59:59.000Z

363

Role of alkyl alcohol on viscosity of silica-based chemical gels for decontamination of highly radioactive nuclear facilities  

SciTech Connect (OSTI)

Silica-based chemical gel for the decontamination of nuclear facilities was prepared by using fumed silica as a viscosifier, a 0.5 M Ce (IV) solution dissolved in concentrated nitric acid as a chemical decontamination agent, and tripropylene glycol butyl ether (TPGBE) as a co-viscosifier. A new effective strategy for the preparation of the chemical gel was investigated by introducing the alkyl alcohols as organic solvents to effectively dissolve the co-viscosifier. The mixture solution of the co-viscosifier and alkyl alcohols was more effective in the control of viscosity than that of the co-viscosifier only in gel. Here, the alkyl alcohols played a key role as an effective dissolution solvent for the co-viscosifier in the preparation of the chemical gel, resulting in a reducing of the amount of the co-viscosifier and gel time compared with that of the chemical gel prepared without the alkyl alcohols. It was considered that the alkyl alcohols contributed to the effective dissolution of the co-viscosifier as well as the homogeneous mixing in the formation of the gel, while the co-viscosifier in an aqueous media of the chemical decontamination agent solution showed a lower solubility. The decontamination efficiency of the chemical gels prepared in this work using a multi-channel analyzer (MCA) showed a high decontamination efficiency of over ca. 94% and ca. 92% for Co-60 and Cs-137 contaminated on surface of the stainless steel 304, respectively. (authors)

Choi, B. S.; Yoon, S. B.; Jung, C. H.; Lee, K. W.; Moon, J. K. [Div. of Decontamination and Decommissioning Technology Development, Korea Atomic Energy Research Inst., Daedeok-daero 989-111, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

2012-07-01T23:59:59.000Z

364

Quasi-continuum photoluminescence: Unusual broad spectral and temporal characteristics found in defective surfaces of silica and other materials  

SciTech Connect (OSTI)

We previously reported a novel photoluminescence (PL) with a distribution of fast decay times in fused silica surface flaws that is correlated with damage propensity by high fluence lasers. The source of the PL was not attributable to any known silica point defect. Due to its broad spectral and temporal features, we here give this PL the name quasi-continuum PL (QC-PL) and describe the features of QC-PL in more detail. The primary features of QC-PL include broad excitation and emission spectra, a broad distribution of PL lifetimes from 20 ps to 5?ns, continuous shifts in PL lifetime distributions with respect to emission wavelength, and a propensity to photo-bleach and photo-brighten. We found similar PL characteristics in surface flaws of other optical materials, including CaF{sub 2}, DKDP, and quartz. Based on the commonality of the features in different optical materials and the proximity of QC-PL to surfaces, we suggest that these properties arise from interactions associated with high densities of defects, rather than a distribution over a large number of types of defects and is likely found in a wide variety of structures from nano-scale composites to bulk structures as well as in both broad and narrow band materials from dielectrics to semiconductors.

Laurence, Ted A., E-mail: laurence2@llnl.gov; Bude, Jeff D.; Shen, Nan; Steele, William A.; Ly, Sonny [Physical and Life Sciences and National Ignition Facility, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

2014-02-28T23:59:59.000Z

365

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

SciTech Connect (OSTI)

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.

Varkentina, N.; Sanner, N.; Lebugle, M.; Sentis, M.; Utéza, O. [Aix-Marseille Université, CNRS, LP3 UMR 7341, 13288 Marseille (France)] [Aix-Marseille Université, CNRS, LP3 UMR 7341, 13288 Marseille (France)

2013-11-07T23:59:59.000Z

366

NEAR-IR TWO PHOTON MICROSCOPY IMAGING OF SILICA NANOPARTICLES FUNCTIONALIZED WITH ISOLATED SENSITIZED Yb(III) CENTERS  

SciTech Connect (OSTI)

Bright nano objects emitting in the near infrared with a maximal cross section of 41.4 x 103 GM (Goppert Mayer), were prepared by implanting ca. 180 4,4 diethylaminostyryl 2,2 bipyridine (DEAS) Yb(III) complexes on the surface of 12 nm silica nanoparticles. The surface complexes ([DEAS Ln SiO2], Ln =Y,Yb) were characterized using IR, solid state NMR, UV Vis, EXAFS spectroscopies in combination 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. Starting from the partial dehydroxylation of the silica at 700 C on high vacuum having 0.8 OH.nm 2, the grafting of Ln(N(SiMe3)2)3 generate ?SiO Ln(N(SiMe3)2)2, which upon thermal step and coordination of the DEAS chromophore yields (?SiO)3Ln(DEAS). Surface and molecular analogues display similar properties, in terms of DEAS binding constants absorption maxima and luminescence properties (intense emission band assigned to a ligand centered CT fluorescence and life time) in the solid state, consistent with the molecular nature of the surface species. The densely functionalized nanoparticles can be dispersed via ultra-sonication in small ca. 15-20 nm aggregates (1 to 6 elementary particles) that were detected using two photon microscopy imaging at 720 nm excitation, making them promising nano objects for bio imaging.

Lapadula, Giuseppe; Bourdolle, Adrien; Allouche, Florian; Conley, Matthew P.; Maron, Laurent; Lukens, Wayne W.; Guyot, Yannick; Andraud, Chantal; Brasselet, Sophie; Copé; ret, Christophe; Maury, Olivier; Andersen, Richard A.

2013-01-12T23:59:59.000Z

367

Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali-silica reaction  

SciTech Connect (OSTI)

Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali-silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali-silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: Black-Right-Pointing-Pointer ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). Black-Right-Pointing-Pointer Cathodoluminescence was combined with various microscopic techniques and image analysis. Black-Right-Pointing-Pointer ASR was attributed to aggregates. Black-Right-Pointing-Pointer Source materials of aggregates were identified based on cathodoluminescence characteristics. Black-Right-Pointing-Pointer Quartz comes from different volcanic, plutonic and metamorphic parent rocks.

Stastna, A., E-mail: astastna@gmail.com [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Sachlova, S.; Pertold, Z.; Prikryl, R. [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Leichmann, J. [Department of Geological Sciences, Faculty of Science, Masaryk University in Brno, Kotlarska 267/2, 611 37 Brno (Czech Republic)

2012-03-15T23:59:59.000Z

368

X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface  

E-Print Network [OSTI]

The spatial structure of the transition region between an insulator and an electrolyte solution was studied with x-ray scattering.The electron density profile across the n-hexane/silica sol interface (solutions with 5-nm, 7-nm, and 12-nm colloidal particles) agrees with the theory of the electrical double layer and shows separation of positive and negative charges. The interface consists of three layers, i.e., a compact layer of Na+, a loose monolayer of nanocolloidal particles as part of a thick diffuse layer, and a low-density layer sandwiched between them. Its structure is described by a model in which the potential gradient at the interface reflects the difference in the potentials of "image forces" between the cationic Na+ and anionic nanoparticles and the specific adsorption of surface charge. The density of water in the large electric field (1-10 GV/m) of the transition region and the layering of silica in the diffuse layer is discussed.

Aleksey M. Tikhonov

2006-09-11T23:59:59.000Z

369

Aerogels: stiff foams composed of up to 99.8% air Silica aerogel is the world's lowest-density solid: 1 mg/cm3  

E-Print Network [OSTI]

#12;Aerogels: stiff foams composed of up to 99.8% air Silica aerogel is the world's lowest-density solid: 1 mg/cm3 Aerogels hold 15 different records for material properties, including best insulator 2.38 g piece of aerogel supports a 2.5 kg brick. #12;#12;#12;l = m Ã? n unit vector in orbital space

Fominov, Yakov

370

Comparing the use of 4.6 um lasers versus 10.6 um lasers for mitigating damage site growth on fused silica surfaces  

SciTech Connect (OSTI)

The advantage of using mid-infrared (IR) 4.6 {micro}m lasers, versus far-infrared 10.6 {micro}m lasers, for mitigating damage growth on fused silica is investigated. In contrast to fused silica's high absorption at 10.6 {micro}m, silica absorption at 4.6 {micro}m is two orders of magnitude less. The much reduced absorption at 4.6 {micro}m enables deep heat penetration into fused silica when it is heated using the mid-IR laser, which in turn leads to more effective mitigation of damage sites with deep cracks. The advantage of using mid-IR versus far-IR laser for damage growth mitigation under non-evaporative condition is quantified by defining a figure of merit (FOM) that relates the crack healing depth to laser power required. Based on our FOM, we show that for damage cracks up to at least 500 {micro}m in depth, mitigation using a 4.6 {micro}m mid-IR laser is more efficient than mitigation using a 10.6 {micro}m far-IR laser.

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

2010-10-21T23:59:59.000Z

371

9/28/98 9:58:58 am, Journal of Non-Crystalline Solids MOLECULAR DYNAMICS SIMULATION OF VITREOUS SILICA STRUCTURES  

E-Print Network [OSTI]

Dynamics (MD) techniques to simulate glass structures has become a valuable tool for gaining insight1 9/28/98 9:58:58 am, Journal of Non-Crystalline Solids MOLECULAR DYNAMICS SIMULATION OF VITREOUS SILICA STRUCTURES Norman T. Huff*, Owens Corning Science and Technology Center, 2790 Columbus Road

Goddard III, William A.

372

Gas-Solid Displacement Reactions for Converting Silica Diatom Frustules into MgO and TiO2  

SciTech Connect (OSTI)

Technology for the microfabrication of freely moving parts began with a Bell Labs microgear spun by an air jet, and electrostatic silicon micro motors in the mid-1980s. It continued with development work on micropositioning of optics, miniature heat exchangers, small fluidic devices, and chemical reaction chambers. Recently, there has been a great deal of interest centered on the design and manufacture of devices of nanometer proportions and this speculation has spawned a new industry named, nanotechnology. Despite the technological and economic promise of this technology, current commercial micro/mesofabrication methods have largely been based upon two-dimensional processing principles which is not well suited to the low-cost mass production of three-dimensional micro devices with complex geometries and meso/nanoscale features. Diatoms are three dimensional (3D) microstructures from nature that provide a practical alternative for nanotechnology and microfabrication. Diatoms (Figure 1) are single-celled micro algae that form rigid cell walls (frustules) composed of amorphous silica. Their dimensions can range from less than 1 micron to several hundreds of microns. They are distributed throughout the world in aquatic, semi-aquatic and moist habitats, and extremely abundant in freshwater and marine ecosystems. Diatoms are thought to be responsible for up to 25% of the world's net primary production of organic carbon (by transforming of carbon dioxide and water into sugars by photosynthesis). Approximately 10{sup 5} unique diatom frustule shapes have been claimed to exist in nature. The frustules are composed of two valves that fit together like a petri-dish, connected to each other by one or more girdle bands. The frustule wall consists of a nanoporous assembly of silica nanoparticles. They absorb soluble silica from water even at extremely low concentrations and metabolize and deposit it as an external skeleton. Continued reproduction of a single parent diatom can yield large numbers of descendant diatoms, each of which possesses a frustule with the same microshape and meso/nano features. Each mitotic division results in the formation of two differently sized daughter cells, one that is the same size as the parent and one that is slightly smaller. Therefore, over successive generations the mean cell size of a population decreases and standard deviation about this mean increases. It is believed that when a cell decreases in size to a diameter of less than about 30 to 40% of the maximum diameter for a given species, sexual reproduction initiates. This enables an entirely new frustule to be generated that is many times larger than either parent. Importantly, these newly formed large cells rapidly resume asexual reproduction and are essentially ''immune'' to sexual reproduction until an appropriate small cell size is obtained.

Tugba Kalem

2004-12-19T23:59:59.000Z

373

Infrared study on the adsorption of CO and NO on silica-supported Pd and Pt-Pd  

SciTech Connect (OSTI)

The IR spectra of NO adsorbed on silica-supported palladium had bands at 1735 and 1645/cm, which were assigned to linearly bound NO and to NO linearly bound to low-coordinated palladium, respectively. Bands at 1980 and 2070/cm in the spectrum of CO adsorbed on palladium were assigned multiply coordinated and linear CO, respectively. Carbon monoxide was completely displaced from palladium by nitric oxide, preadsorbed nitric oxide was partly displaced from palladium by carbon monoxide, and carbon dioxide and nitrous oxide were formed in both processes. A band at 2180/cm provided evidence for adsorbed isocyanate species. All bands shifted to higher frequencies by approx. 10/cm for 1:1 palladium/platinum bimetallic clusters; the carbon monoxide was readily removed by evacuating at room temperature, a fact that my be used in catalyst surface area determinations.

Grill, C.M.; Gonzalez, R.D.

1980-04-17T23:59:59.000Z

374

Development of EEM based silicon–water and silica–water wall potentials for non-reactive molecular dynamics simulations  

SciTech Connect (OSTI)

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 fluid–solid interface for a long time. In this work, the conceptual idea of Steele's potential was extended in order to simulate water–silicon and water–silica 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 silicon–water contact angle of 129°, a quartz–water contact angle of 0°, and a cristobalite–water contact angle of 40°, which are in reasonable agreement with experimental values.

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

2014-07-01T23:59:59.000Z

375

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

SciTech Connect (OSTI)

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.

Mady, Franck, E-mail: franck.mady@unice.fr; Duchez, Jean-Bernard, E-mail: franck.mady@unice.fr; Mebrouk, Yasmine, E-mail: franck.mady@unice.fr; Benabdesselam, Mourad, E-mail: franck.mady@unice.fr [University of Nice Sophia Antipolis, Laboratoire de Physique de la Matière Condensée (LPMC), CNRS UMR 7336, Parc Valrose, 06108 Nice cedex 2 (France)

2014-10-21T23:59:59.000Z

376

Progress in development of silica aerogel for particle- and nuclear-physics experiments at J-PARC  

E-Print Network [OSTI]

This study presents the advancement in hydrophobic silica aerogel development for use as Cherenkov radiators and muonium production targets. These devices are scheduled for use in several particle- and nuclear-physics experiments that are planned in the near future at the Japan Proton Accelerator Research Complex. Our conventional method to produce aerogel tiles with an intermediate index of refraction of approximately 1.05 is extended so that we can now produce aerogel tiles with lower indices of refraction (i.e., 1.03-1.04) and higher indices of refraction (i.e., 1.075-1.08); each with excellent transparency. A new production method, called pin drying, was optimized to produce larger area aerogels consistently with an ultrahigh index of refraction (>1.10). In addition, for use as a thermal-muonium-emitting material at room temperature, dedicated low-density aerogels were fabricated using the conventional method.

Makoto Tabata; Hideyuki Kawai

2014-10-09T23:59:59.000Z

377

Design of a silica-aerogel-based cosmic dust collector for the Tanpopo mission aboard the International Space Station  

E-Print Network [OSTI]

We are developing a silica-aerogel-based cosmic dust collector for use in the Tanpopo experiment to be conducted on the International Space Station. The mass production of simple two-layer hydrophobic aerogels was undertaken in a contamination-controlled environment, yielding more than 100 undamaged products. The collector, comprising an aerogel tile and holder panel, was designed to resist launch vibration and to conform to an exposure attachment. To this end, a box-framing aerogel with inner and outer densities of 0.01 and 0.03 g/cm$^3$, respectively, was fabricated. The aerogel mounted in the panel passed random vibration tests at the levels of the acceptance and qualification tests for launch. It also withstood the pressure changes expected in the airlock on the International Space Station.

Tabata, Makoto; Yano, Hajime; Hashimoto, Hirofumi; Kawai, Hideyuki; Kawaguchi, Yuko; Kobayashi, Kensei; Mita, Hajime; Okudaira, Kyoko; Sasaki, Satoshi; Yabuta, Hikaru; Yokobori, Shin-ichi; Yamagishi, Akihiko

2014-01-01T23:59:59.000Z

378

Ultraviolet-infrared femtosecond laser-induced damage in fused silica and CaF{sub 2} crystals  

SciTech Connect (OSTI)

The damage in fused silica and CaF{sub 2} crystals induced by wavelength tunable femtosecond lasers is studied. The threshold fluence is observed to increase rapidly with laser wavelength {lambda} in the region of 250-800 nm, while it is nearly a constant for 800<{lambda}<2000 nm. The ultrafast electronic excitation is also studied by a pump and probe method. The reflectivity increases rapidly in the latter half of pump pulse, which supports that impact ionization plays an important role in the generation of conduction band electrons (CBEs). We study the CBEs absorption via subconduction-band (sub-CB) transition, and develop a coupled avalanche model. Our results indicate that the CBEs absorption via sub-CB transition plays an important role in the damage in dielectrics irradiated by the visible and near ultraviolet femtosecond lasers. Our theory explains well the experiments.

Jia, T. Q.; Chen, H. X.; Huang, M.; Zhao, F. L.; Li, X. X.; Xu, S. Z.; Sun, H. Y.; Feng, D. H.; Li, C. B.; Wang, X. F.; Li, R. X.; Xu, Z. Z.; He, X. K.; Kuroda, H. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); and State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai (China); State Key Laboratory of Optoelectronic Materials and Technologies, Zhongshan University, Guangzhou, 510275 (China); State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai (China); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

2006-02-01T23:59:59.000Z

379

Progress in development of silica aerogel for particle- and nuclear-physics experiments at J-PARC  

E-Print Network [OSTI]

This study presents the advancement in hydrophobic silica aerogel development for use as Cherenkov radiators and muonium production targets. These devices are scheduled for use in several particle- and nuclear-physics experiments that are planned in the near future at the Japan Proton Accelerator Research Complex. Our conventional method to produce aerogel tiles with an intermediate index of refraction of approximately 1.05 is extended so that we can now produce aerogel tiles with lower indices of refraction (i.e., 1.03-1.04) and higher indices of refraction (i.e., 1.075-1.08); each with excellent transparency. A new production method, called pin drying, was optimized to produce larger area aerogels consistently with an ultrahigh index of refraction (>1.10). In addition, for use as a thermal-muonium-emitting material at room temperature, dedicated low-density aerogels were fabricated using the conventional method.

Tabata, Makoto

2014-01-01T23:59:59.000Z

380

Thermal imaging investigation of modified fused silica at surface damage sites for understanding the underlying mechanisms of damage growth  

SciTech Connect (OSTI)

We use an infrared thermal imaging system in combination with a fluorescence microscope to map the dynamics of the local surface temperature and fluorescence intensity under cw, UV excitation of laser-modified fused silica within a damage site. Based on a thermal diffusion model, we estimate the energy deposited via linear absorption mechanisms and derive the linear absorption coefficient of the modified material. The results indicate that the damage growth mechanism is not entirely based on linear absorption. Specifically, the absorption cross-section derived above would prove insufficient to cause a significant increase in the temperature of the modified material under nanosecond, pulsed excitation (via linear absorption at ICF laser fluences). In addition, irreversible changes in the absorption cross-section following extended cw, UV laser exposure were observed.

Negres, R A; Burke, M W; DeMange, P; Sutton, S B; Feit, M D; Demos, S G

2006-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
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381

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

SciTech Connect (OSTI)

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.

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

2009-12-16T23:59:59.000Z

382

Comparing the use of mid-infrared versus far-infrared lasers for mitigating damage growth on fused silica  

SciTech Connect (OSTI)

Laser-induced growth of optical damage can limit component lifetime and, therefore, increase 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, we quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {mu}m) versus far-IR (10.6 {mu}m) lasers in mitigating damage growth on fused silica surfaces. The nonlinear 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 {mu}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 IR radiometry, as well as subsurface 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 our FOM, we show that, for cracks up to at least 500 {mu}m in depth, mitigation with a 4.6 {mu}m mid-IR laser is more efficient than mitigation with a 10.6 {mu}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 {mu}m in depth.

Yang, Steven T.; Matthews, Manyalibo J.; Elhadj, Selim; Cooke, Diane; Guss, Gabriel M.; Draggoo, Vaughn G.; Wegner, Paul J.

2010-05-10T23:59:59.000Z

383

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

SciTech Connect (OSTI)

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.

Abbasi-Firouzjah, M. [Laser and Plasma Research Institute, Shahid Beheshti University G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Shokri, B. [Laser and Plasma Research Institute, Shahid Beheshti University G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of) [Laser and Plasma Research Institute, Shahid Beheshti University G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University G.C., Evin, Tehran (Iran, Islamic Republic of)

2013-12-07T23:59:59.000Z

384

Phase behavior of carbon dioxide confined in silica aerogel in the vicinity of the bulk critical point  

SciTech Connect (OSTI)

The small angle neutron scattering intensities from silica aerogel filled with carbon dioxide at different loading densities of the bulk fluid (0.3-0.65 g/cm{sup 3}) were measured at fixed volume condition as a function of decreasing temperature, from 35 to 25 C, to characterize the phase behavior of the confined CO2 about the critical point of the bulk CO{sub 2}. The data present no evidence of a bulklike phase transition of the confined CO{sub 2} in the explored parameter region. They show that the confined CO{sub 2} may be approximated as a two phase system. The first phase (liquid film) is formed by CO{sub 2} molecules at the silica surface, and the second phase (confined fluid) fills up the rest of the pore volume. The thickness {delta} of the liquid film as well as the scattering-length densities of the two phases were obtained by analyzing the Porod invariants and the oscillations observed in the Porod plots at each loading density and temperature. The resulting {delta} values vary in the range 25-45 {angstrom} depending on the temperature and loading density. The density of the liquid film is 1.5-2 times larger than that of the confined fluid, which in its turn exceeds the density of bulk CO{sub 2} at similar temperature and pressure. At the lowest temperature (25 C), the densities of the liquid film and confined fluid respectively approach 1.25 g/cm{sup 3} and 0.8 g/cm{sup 3} independently of the loading conditions.

Ciccariello, Salvino [Universita di Padova; Melnichenko, Yuri B [ORNL; He, Lilin [ORNL

2011-01-01T23:59:59.000Z

385

Remaining Sites Verification Package for the 100-F-44:4, Discovery Pipeline in Silica Gel Pit, Waste Site Reclassification Form 2008-030  

SciTech Connect (OSTI)

The 100-F-44:4, Discovery Pipeline in Silica Gel Pit subsite is located in the 100-FR-1 Operable Unit of the Hanford Site, near the location of the former 110-F Gas Storage Tanks structure. The 100-F-44:4 subsite is a steel pipe discovered October 17, 2004, during trenching to locate the 118-F-4 Silica Gel Pit. Based on visual inspection and confirmatory investigation sampling data, the 100-F-44:4 subsite is a piece of non-hazardous electrical conduit debris. The 100-F-44:4 subsite supports unrestricted future use of shallow zone soil and is protective of groundwater and the Columbia River. No residual contamination exists within the deep zone. Therefore, no deep zone institutional controls are required.

J. M. Capron

2008-09-23T23:59:59.000Z

386

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

SciTech Connect (OSTI)

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.

Schultz, K.J.

1986-04-01T23:59:59.000Z

387

Infrared spectroscopic studies of carbon monoxide adsorbed on a series of silica-supported copper catalysts in different oxidation states  

SciTech Connect (OSTI)

Infrared spectroscopy has been used to study the adsorption of carbon monoxide (358-493 K, 0.1-20 kPa) on four copper-on-silica (2-10 wt% Cu) catalysts prepared by the ion-exchange technique. The measurements are made for each sample in three different states: unreduced (predominantly Cu{sup 2+}), and reduced (Cu{sup 0}), and partially reoxidized in nitrous oxide (Cu{sup +}). On unreduced samples, a major absorption band between 2127 and 2132 cm{sup {minus}1} due to CO adsorbed on small CuO particles and a weak band at 2199 cm{sup {minus}1} due to CO on isolated Cu{sup 2+} ions incorporated in the silica surface have been identified. The former adsorption obeys a Langmuir isotherm with a heat of adsorption of 29 kJ/mol independent of CuO particle size and surface coverage. After catalyst reduction, the major absorption band lies between 2090 and 2113 cm{sup {minus}1} and arises from CO linearly bound to very small (1- to 5-nm) copper metal clusters. The observed frequency shifts indicate the presence of steps and terraces similar to low index Cu planes in very small particles (1- to 2-nm), and the presence of similar higher index Cu planes on larger clusters (2- to 5-nm). The absorption is described by a Freundlich isotherm with the heat of CO adsorption decreasing with coverage from 50 to 22 kJ/mol on bigger particles but more constant (27 to 22 kJ/mol) on small particles. A surface copper/CO atomic ratio increasing from 5 to 12 is established at equilibrium saturation between 358 and 493 K using extinction coefficients determined in this study. In the reduced catalysts, a weakly adsorbed ({Delta}H{sub a} = {minus}20 kJ/mol) species assigned to CO bound to isolated Cu{sup +} ions is also found and absorbs at 2175 cm{sup {minus}1}. The frequency of this band does not vary with catalyst loading and is not affected by reoxidation of the catalyst in nitrous oxide.

Kohler, M.A.; Wainwright, M.S.; Trimm, D.L.; Cant, N.W. (Macquarie Univ., New South Wales (Australia) Univ. of South Wales (Australia))

1989-05-01T23:59:59.000Z

388

Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing  

SciTech Connect (OSTI)

The distribution and characteristics of surface cracks (i.e., sub-surface damage or scratching) on fused silica formed during grinding/polishing resulting from the addition of rogue particles in the base slurry has been investigated. Fused silica samples (10 cm diameter x 1 cm thick) were: (1) ground by loose abrasive grinding (alumina particles 9-30 {micro}m) on a glass lap with the addition of larger alumina particles at various concentrations with mean sizes ranging from 15-30 {micro}m, or (2) polished (using 0.5 {micro}m cerium oxide slurry) on various laps (polyurethanes pads or pitch) with the addition of larger rogue particles (diamond (4-45 {micro}m), pitch, dust, or dried Ceria slurry agglomerates) at various concentrations. For the resulting ground samples, the crack distributions of the as-prepared surfaces were determined using a polished taper technique. The crack depth was observed to: (1) increase at small concentrations (>10{sup -4} fraction) of rogue particles; and (2) increase with rogue particle concentration to crack depths consistent with that observed when grinding with particles the size of the rogue particles alone. For the polished samples, which were subsequently etched in HF:NH{sub 4}F to expose the surface damage, the resulting scratch properties (type, number density, width, and length) were characterized. The number density of scratches increased exponentially with the size of the rogue diamond at a fixed rogue diamond concentration suggesting that larger particles are more likely to lead to scratching. The length of the scratch was found to increase with rogue particle size, increase with lap viscosity, and decrease with applied load. At high diamond concentrations, the type of scratch transitioned from brittle to ductile and the length of the scratches dramatically increased and extended to the edge of the optic. The observed trends can explained semi-quantitatively in terms of the time needed for a rogue particle to penetrate into a viscoelastic lap. The results of this study provide useful insights and 'rules-of-thumb' relating scratch characteristics observed on surfaces during optical glass fabrication to the characteristics rogue particles causing them and their possible source.

Suratwala, T I; Steele, R; Feit, M D; Wong, L; Miller, P E; Menapace, J A; Davis, P J

2007-05-02T23:59:59.000Z

389

INSTRUMENTS-METHODS-36 Absorption and scattering lengths of high density silica aerogels with n = 1.07  

E-Print Network [OSTI]

Charged particle identification at the PANDA experiment will be performed over a wide range of momenta by ?erenkov detectors. One option to identify higher momentum charged particles under small polar angles could be the use of silica aerogels as radiator. Simultaneously, an aerogel ?erenkov counter is being designed for the Kaos spectrometer at the Mainz Microtron MAMI for the discrimination between kaons and pions of momenta ? 1GeV/c. For the simulation of such detectors, the optical properties of the aerogel are needed as input data. We have measured the wavelength dependence of the transmittance (T) and reflectivity (R) of high density aerogel with n ? 1.07, made by Chiba U. in Japan. The characteristic absorption length (?abs) and scattering length (?scat) were extracted by fitting ?abs and ?scat to T. Table 1: The absorption and scattering lengths at different aerogel thicknesses (at ? = 500 nm). Deviations of values at different thicknesses may indicate that the simple powerlaw dependance assumed in Eq. (2) is inappropriate, as also established by [2]. d 2 cm 4 cm 9 cm ?abs 10.1 cm 9.1 cm 7.9 cm ?scat 10.8 cm 13.7 cm 13.5 cm The results are in fair agreement with the values obtained by [1]. These parameters have also been measured at different thicknesses of the aerogel by selecting different tile orientations. The corresponding absorption and scattering lengths at the wavelength seen by PMTs (? ? 500 nm) are shown in Table 1. Such high losses in the aerogel lead to a very low number of deteced photons. Figure 1: Transmittance (T) and reflectivity (R) as a function of the wavelength for silica aerogel with n ? 1.07. The transmittance between 200 nm and 800 nm of two aerogel tiles has been measured at different positions on the surface to scan for potential inhomogeneity and to obtain averaged values, see Fig. 1. From these measurements the scattering length, the absorption length and the attenuation length have been deduced by applying the following relation T(?) = (1 ? R(?))exp

L. Debenjak; P. Achenbach; J. Pochodzalla; T. Saito

390

X-ray micro-tomography investigation of the foaming process in the system of waste glass–silica mud–MnO{sub 2}  

SciTech Connect (OSTI)

In case of foamed lightweight aggregates (LWAs), porosity is introduced by the addition of a foaming agent to the glassy matrix, which degasses at an elevated temperature, so that the resulting gases remain trapped inside the glassy structure. The efficiency of action of MnO{sub 2} as a foaming agent in waste glass and waste glass/silica mud systems was studied. Samples were fired at different temperatures and with different dwelling times at a certain temperature, and the development of porosity was investigated by means of X-ray micro-tomography. It was found that, with the prolongation in dwelling times, the number of pores decreased, while, on the other hand, the volume of these pores increased, and that the addition of silica mud increases the foaming temperature and slows down the foaming process. - Highlights: • Preparation of lightweight aggregate from waste glass, silica sludge, and MnO{sub 2} • DTA/TG investigation of MnO{sub 2} • Characterization of pore-forming process by means of X-ray micro-tomography (?cT)

Ducman, V., E-mail: vilma.ducman@zag.si [ZAG Ljubljana, Dimi?eva 12, 1000 Ljubljana (Slovenia); Korat, L.; Legat, A. [ZAG Ljubljana, Dimi?eva 12, 1000 Ljubljana (Slovenia); Mirti?, B. [NTF, Ašker?eva 12, 1000 Ljubljana (Slovenia)

2013-12-15T23:59:59.000Z

391

Novel nanomaterials based on 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin entrapped in silica matrices  

SciTech Connect (OSTI)

The present study is dealing with the obtaining of transparent hybrid silica materials encapsulating 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)-21H,23H-porphyrin designated for advanced optoelectronic devices. The porphyrin was synthesized by three methods: an Adler-type reaction between pyrrole and 3,4-dimethoxybenzaldehyde in propionic acid medium; by Lindsey condensation of pyrrole with 3,4-dimethoxybenzaldehyde in the presence of BF{sub 3}.OEt{sub 2} and by a multicomponent reaction by simultaneously using of pyrrole and two different aldehydes: 3,4-dimethoxybenzaldehyde and 3-hydroxybenzaldehyde. The 3,4-dimethoxyphenyl substituted porphyrin was characterized by HPLC, TLC, UV-vis, FT-IR, {sup 1}H NMR and {sup 13}C NMR analysis. Excitation and emission spectra were also discussed in terms of pH conditions. The hybrid materials, consisting in the porphyrin encapsulated in silica matrices, have been prepared successfully via the two steps acid-base catalyzed hydrolysis and condensation of tetraethylorthosilicate using different approaches of the sol-gel process: in situ, by impregnation and by sonication. The synthetic conditions and the compositions were monitored and characterized by using spectroscopic methods such as FT-IR, fluorescence and UV-vis. Atomic force microscopy (AFM) has been applied to observe the columnar or pyramidal nanostructures which are formed by the immobilization of porphyrin on the silica matrices.

Fagadar-Cosma, Eugenia, E-mail: efagadar@yahoo.com [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazu Ave, No. 24, 300223 Timisoara (Romania)] [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazu Ave, No. 24, 300223 Timisoara (Romania); Enache, Corina [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazu Ave, No. 24, 300223 Timisoara (Romania)] [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazu Ave, No. 24, 300223 Timisoara (Romania); Vlascici, Dana [West University of Timisoara, Pestalozzi Street, No. 16, 300115 Timisoara (Romania)] [West University of Timisoara, Pestalozzi Street, No. 16, 300115 Timisoara (Romania); Fagadar-Cosma, Gheorghe ['Politehnica' University, T. Lalescu Street, No. 2, 300223 Timisoara (Romania)] ['Politehnica' University, T. Lalescu Street, No. 2, 300223 Timisoara (Romania); Vasile, Mihaela [National Institute for Research and Development in Electrochemistry and Condensed Matter, P. Andronescu Street, No. 1, 300224 Timisoara (Romania)] [National Institute for Research and Development in Electrochemistry and Condensed Matter, P. Andronescu Street, No. 1, 300224 Timisoara (Romania); Bazylak, Grzegorz [Collegium Medicum, Nicolaus Copernicus University, Department of Pharmaco-Bromatology and Molecular Nutrition, Jagiellonska, No. 13, PL-85-067 Bydgoszcz (Poland)] [Collegium Medicum, Nicolaus Copernicus University, Department of Pharmaco-Bromatology and Molecular Nutrition, Jagiellonska, No. 13, PL-85-067 Bydgoszcz (Poland)

2009-12-15T23:59:59.000Z

392

Visible Light-Driven Water Oxidation by Ir oxide Clusters Coupledto Single Cr Centers in Mesoporous Silica  

SciTech Connect (OSTI)

Visible light-induced water oxidation has been demonstrated at an Ir oxide nanocluster coupled to a single Cr{sup VI} site on the pore surface of MCM-41 mesoporous silica. The photocatalytic unit was assembled by the reaction of surface Cr=O groups with Ir(acac){sub 3} precursor followed by calcination at 300 C and bond formation monitored by FT-Raman and FT-IR spectroscopy. High-resolution Z-contrast electron micrographs of the calcined material combined with energy-dispersive X-ray spot analysis confirmed the occlusion of Ir oxide nanoparticles inside the mesopores. Oxygen evolution of an aqueous suspension of the Ir{sub x}O{sub y}-CrMCM-41 upon visible light irradiation of the Cr{sup VI}-O ligand-to-metal charge-transfer absorption was monitored mass-spectrometrically. Comparison of the product yields for samples with low Cr content (Cr/Si {le} 0.02) and high Cr content (Cr/Si = 0.05) indicates that only isolated Cr centers are capable of extracting electrons from Ir oxide clusters, while di- or polychromate species are not. Water oxidation at a multielectron-transfer catalyst coupled to a single metal center has not been demonstrated before. The ability to drive water oxidation with a single metal center as electron pump offers opportunities for coupling the oxygen-evolving photocatalytic unit to reducing sites in the nanoporous scaffold.

Nakamura, Ryuhei; Frei, Heinz

2006-07-10T23:59:59.000Z

393

Silica aerogel radiator for use in the A-RICH system utilized in the Belle II experiment  

E-Print Network [OSTI]

This paper presents recent progress in the development and mass production of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter, which will be installed in the forward end cap of the Belle II detector. The proximity-focusing A-RICH system is especially designed to identify charged kaons and pions. The refractive index of the installed aerogel Cherenkov radiators is approximately 1.05, and we aim for a separation capability exceeding 4$\\sigma $ at momenta up to 4 GeV/$c$. Large-area aerogel tiles (over 18 $\\times $ 18 $\\times $ 2 cm$^3$) were first fabricated in test productions by pin drying in addition to conventional methods. We proposed to fill the large end-cap region (area 3.5 m$^2$) with 124 water-jet-trimmed fan-shaped dual-layer-focusing aerogel combinations of different refractive indices (1.045 and 1.055). Guided by the test production results, we decided to manufacture aerogels by the conventional method and are currently procee...

Tabata, Makoto; Hamada, Nao; Hara, Koji; Iijima, Toru; Iwata, Shuichi; Kakuno, Hidekazu; Kawai, Hideyuki; Korpar, Samo; Križan, Peter; Kumita, Tetsuro; Nishida, Shohei; Ogawa, Satoru; Pestotnik, Rok; Šantelj, Luka; Seljak, Andrej; Sumiyoshi, Takayuki; Tahirovi?, Elvedin; Yoshida, Keisuke; Yusa, Yosuke

2014-01-01T23:59:59.000Z

394

Silica aerogel radiator for use in the A-RICH system utilized in the Belle II experiment  

E-Print Network [OSTI]

This paper presents recent progress in the development and mass production of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter, which will be installed in the forward end cap of the Belle II detector. The proximity-focusing A-RICH system is especially designed to identify charged kaons and pions. The refractive index of the installed aerogel Cherenkov radiators is approximately 1.05, and we aim for a separation capability exceeding 4$\\sigma $ at momenta up to 4 GeV/$c$. Large-area aerogel tiles (over 18 $\\times $ 18 $\\times $ 2 cm$^3$) were first fabricated in test productions by pin drying in addition to conventional methods. We proposed to fill the large end-cap region (area 3.5 m$^2$) with 124 water-jet-trimmed fan-shaped dual-layer-focusing aerogel combinations of different refractive indices (1.045 and 1.055). Guided by the test production results, we decided to manufacture aerogels by the conventional method and are currently proceeding with mass production. In an electron beam test undertaken at the DESY, we confirmed that the $K$/$\\pi $ separation capability of a prototype A-RICH counter exceeded 4$\\sigma $ at 4 GeV/$c$.

Makoto Tabata; Ichiro Adachi; Nao Hamada; Koji Hara; Toru Iijima; Shuichi Iwata; Hidekazu Kakuno; Hideyuki Kawai; Samo Korpar; Peter Križan; Tetsuro Kumita; Shohei Nishida; Satoru Ogawa; Rok Pestotnik; Luka Šantelj; Andrej Seljak; Takayuki Sumiyoshi; Elvedin Tahirovi?; Keisuke Yoshida; Yosuke Yusa

2014-06-18T23:59:59.000Z

395

An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser  

SciTech Connect (OSTI)

A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L

2010-10-21T23:59:59.000Z

396

Imaging System to Measure Kinetics of Material Cluster Ejection During Exit-Surface Damage Initiation and Growth in Fused Silica  

SciTech Connect (OSTI)

Laser-induced damage on the surface of optical components typically is manifested by the formation of microscopic craters that can ultimately degrade the optics performance characteristics. It is believed that the damage process is the result of the material exposure to high temperatures and pressures within a volume on the order of several cubic microns located just below the surface. The response of the material following initial localized energy deposition by the laser pulse, including the timeline of events and the individual processes involved during this timeline, is still largely unknown. In this work we introduce a time-resolved microscope system designed to enable a detailed investigation of the sequence of dynamic events involved during surface damage. To best capture individual aspects of the damage timeline, this system is employed in multiple imaging configurations (such as multi-view image acquisition at a single time point and multi-image acquisition at different time points of the same event) and offers sensitivity to phenomena at very early delay times. The capabilities of this system are demonstrated with preliminary results from the study of exit-surface damage in fused silica. The time-resolved images provide information on the material response immediately following laser energy deposition, the processes later involved during crater formation or growth, the material ejecta kinetics, and overall material motion and transformation. Such results offer insight into the mechanisms governing damage initiation and growth in the optical components of ICF class laser systems.

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

2009-10-29T23:59:59.000Z

397

Investigations of laser-induced damages in fused silica optics using x-ray laser interferometric microscopy  

SciTech Connect (OSTI)

A novel x-ray laser (XRL) application, aimed at understanding the microscopic effects involved in formation of laser-induced damage in optical materials exposed to high-power sub-ns laser pulses, is presented. Standard fused silica substrates with permanent damage threshold below 20 J/cm{sup 2}, when irradiated by 438 nm laser pulses, were probed in situ by a neonlike zinc XRL at 21.2 nm. The probing beamline employed a double Lloyd's mirror x-ray interferometer, used in conjunction with an imaging mirror to achieve magnification of {approx}8. In conjunction with an array of in situ optical diagnostics, the main question addressed is whether the damage on the rear surface of the beamsplitter is transient or permanent. The second issue, examined by both the x-ray interferometric microscopy and the optical diagnostics, is whether a local rear-surface modification is associated with nonlinear effects such as self-focusing or filamentation of the damaging laser beam in the bulk.

Margarone, D.; Rus, B.; Kozlova, M.; Nejdl, J.; Mocek, T.; Homer, P.; Polan, J.; Stupka, M. [Department of X-ray Lasers/PALS Centre, Institute of Physics of the ASCR, 18221 Prague 8 (Czech Republic); Cassou, K.; Kazamias, S.; Lagron, J. C.; Ros, D. [LIXAM, Universite Paris-Sud, 91405 Orsay (France); Danson, C.; Hawkes, S. [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom)

2010-05-15T23:59:59.000Z

398

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

SciTech Connect (OSTI)

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.

Huang, Yantang, E-mail: g@fzu.edu.cn; Huang, Yu; Zhang, Peijin [College of Physics and Information Engineering, Fuzhou University, Fu Zhou, 350108 (China)] [College of Physics and Information Engineering, Fuzhou University, Fu Zhou, 350108 (China); Guo, Changlei [College of Physics and Information Engineering, Fuzhou University, Fu Zhou, 350108 (China) [College of Physics and Information Engineering, Fuzhou University, Fu Zhou, 350108 (China); Department of Electronic Engineering, Institute of Optoelectronic Technology, Xiamen University, Xiamen, 361005 (China)

2014-02-15T23:59:59.000Z

399

Hydrogenolysis of methyl formate over copper on silica. I. Study of surface species by in situ infrared spectroscopy  

SciTech Connect (OSTI)

The hydrogenolysis of methyl formate to methanol over silica-supported copper has been studied using in situ infrared spectroscopy coupled with simultaneous determination of rate. Under flow reaction conditions two forms of adsorbed methyl formate exist. One has a carbonyl absorption at 1726 cm/sup -1/ and is bound to the support by the hydrogen bonding with a heat of adsorption of 65 kJ mol/sup -1/. The second absorbs at 1666 cm/sup -1/ and is bound to copper with an approximate heat of adsorption of 140 kJ mol/sup -1/. At 457 K the hydrogenolysis rate is directly proportional to the band intensity of the latter and hence it, or another species in equilibrium with it, is involved in the rate-determining step. Adsorption of CO from CO/H/sub 2/ mixtures gives rise to a single infrared band at 2117 cm/sup -1/, the corresponding heat of adsorption being 60 kJ mol/sup -1/. Competitive measurements under hydrogenolysis conditions show that methyl formate will partially displace adsorbed CO and not vice versa. Nonetheless CO does reversibly inhibit the rate and this is attributed to its adsorption displacing hydrogen from the surface. The lower concentration of surface hydrogen also reduces the rate of hydrogenation of a formaldehyde intermediate leading to its deposition as a polymer as revealed by infrared bands at 1483 and 1375 cm/sup -1/. The same polymer accretes more rapidly during the reverse methanol to methyl formate reaction for which CO is a substantial by-product and hydrogen pressures are much lower than used for hydrogenolysis. Continuous deactivation of the catalyst is then observed.

Monti, D.M.; Cant, N.W.; Trimm, D.L.; Wainwright, M.S.

1986-07-01T23:59:59.000Z

400

In situ formation of sintered cordierite–mullite nano–micro composites by utilizing of waste silica fume  

SciTech Connect (OSTI)

Highlights: ? We succeeded to obtain in situ formed sintered cordierite–mullite nano–macro 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 cordierite–mullite nano–macro 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 nano–macro cordierite–mullite structures. -- Abstract: This study aims at in situ formation of sintered cordierite–mullite nano–macro 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 cordierite–mullite 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 cordierite–mullite nano–macro 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 cordierite–mullite nano–macro composites were in-situ formed at 1400 °C. The batch containing 70 wt.% cordierite showed good physical and mechanical properties.

Khattab, R.M.; EL-Rafei, A.M. [Refractories, Ceramics and Building Materials Dept., National Research Center, 12622 Dokki, Cairo (Egypt)] [Refractories, Ceramics and Building Materials Dept., National Research Center, 12622 Dokki, Cairo (Egypt); Zawrah, M.F., E-mail: mzawrah@hotmail.com [Refractories, Ceramics and Building Materials Dept., National Research Center, 12622 Dokki, Cairo (Egypt)

2012-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

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

SciTech Connect (OSTI)

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.

Kim, So Youn; Zukoski, Charles F. (UIUC)

2014-09-24T23:59:59.000Z

402

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

SciTech Connect (OSTI)

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)

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)

2005-01-01T23:59:59.000Z

403

Controlled Assembly of Heterobinuclear Sites on Mesoporous Silica: Visible Light Charge-Transfer Units with Selectable Redox Properties  

SciTech Connect (OSTI)

Mild synthetic methods are demonstrated for the selective assembly of oxo-bridged heterobinuclear units of the type TiOCrIII, TiOCoII, and TiOCeIII on mesoporous silica support MCM-41. One method takes advantage of the higher acidity and, hence, higher reactivity of titanol compared to silanol OH groups towards CeIII or CoII precursor. The procedure avoids the customary use of strong base. The controlled assembly of the TiOCr system exploits the selective redox reactivity of one metal towards another (TiIII precursor reacting with anchored CrVI centers). The observed selectivity for linking a metal precursor to an already anchored partner versus formation of isolated centers ranges from a factor of six (TiOCe) to complete (TiOCr, TiOCo). Evidence for oxo bridges and determination of the coordination environment of each metal centers is based on K-edge EXAFS (TiOCr), L-edge absorption spectroscopy (Ce), and XANES measurements (Co, Cr). EPR, optical, FT-Raman and FT-IR spectroscopy furnish additional details on oxidation state and coordination environment of donor and acceptor metal centers. In the case of TiOCr, the integrity of the anchored group upon calcination (350 oC) and cycling of the Cr oxidation state is demonstrated. The binuclear units possess metal-to-metal charge-transfer transitions that absorb deep in the visible region. The flexible synthetic method for assembling the units opens up the use of visible light charge transfer pumps featuring donor or acceptor metals with selectable redox potential.

Frei, Heinz; Han, Hongxian; Frei, Heinz

2008-06-04T23:59:59.000Z

404

Simulation of Infrared Laser Heating of Silica Using Heat Conduction and Multifrequency Radiation Diffusion Equations Adapted for Homogeneous Refractive Lossy Media  

SciTech Connect (OSTI)

Localized, transient heating of materials using micro-scale, highly absorbing laser light has been used in many industries to anneal, melt and ablate material with high precision. Accurate modeling of the relative contributions of conductive, convective and radiative losses as a function of laser parameters is essential to optimizing micro-scale laser processing of materials. In bulk semi-transparent materials such as silicate glass melts, radiation transport is known to play a significantly larger role as the temperature increases. Conventionally, radiation is treated in the frequency-averaged diffusive limit (Rosseland approximation). However, the role and proper treatment of radiative processes under rapidly heated, high thermal gradient conditions, often created through laser-matter interactions, is at present not clear. Starting from the radiation transport equation for homogeneous, refractive lossy media, they derive the corresponding time-dependent multi-frequency diffusion equations. Zeroth and first moments of the transport equation couple the energy density, flux and pressure tensor. The system is closed by neglecting the temporal derivative of the flux and replacing the pressure tensor by its diagonal analogue. The radiation equations are coupled to a diffusion equation for the matter temperature. They are interested in modeling infrared laser heating of silica over sub-millimeter length scales, and at possibly rapid rates. Hence, in contrast to related work, they retain the temporal derivative of the radiation field. They derive boundary conditions at a planar air-silica interface taking account of reflectivities obtained from the Fresnel relations that include absorption. The effect of a temperature-dependent absorption index is explored through construction of a multi-phonon dielectric function that includes mode dispersion. The spectral dimension is discretized into a finite number of intervals yielding a system of multigroup diffusion equations. Simulations are presented. To demonstrate the bulk heat loss due to radiation and the effect of the radiation's temporal derivative, they model cooling of a silica slab, initially at 2500 K, for 10 s. Retaining the derivative enables correctly modeling the loss of photons initially present in the slab. Other simulations model irradiating silica discs (of approximately 5 mm radii and thickness) with a CO2 laser: {lambda} = 10.59 and 4.6 um, Gaussian profile, r{sub 0} = 0.5 mm for 1/e decay. By surrounding the disks in room-temperature air, they make use of the boundary conditions described above.

Shestakov, A I; Matthews, M J; Vignes, R M; Stolken, J S

2010-10-28T23:59:59.000Z

405

Optical characterization of n=1.03 silica aerogel used as radiator in the RICH of E. Aschenauer 9 , N. Bianchi 4 , G.P. Capitani 4 , P. Carter 3 , C Casalino 2 , E. Cisbani 6 , C. Coluzza 7 , R. De Leo 2;a ,  

E-Print Network [OSTI]

Optical characterization of n=1.03 silica aerogel used as radiator in the RICH of HERMES E Abstract The optical properties of silica aerogel tiles with a refractive index of 1.03 and dimensions 11, is completely interpretable as backscattering from inside the aerogel, revealing an absence of light reflection

406

Preparation of magnetic photocatalyst nanoparticles—TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite—and its photocatalytic activity influenced by silica interlayer  

SciTech Connect (OSTI)

Highlights: ? TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite acts as magnetic photocatalyst nanoparticle. ? SiO{sub 2} interlayer is used to prevent electron migration between photocatalyst and magnetic core. ? TiO{sub 2}/Mn–Zn ferrite without SiO{sub 2} interlayer shows poor magnetic and photocatalytic property. -- Abstract: A magnetic photocatalyst, TiO{sub 2}/SiO{sub 2}/Mn–Zn ferrite, was prepared by stepwise synthesis involving the co-precipitation of Mn–Zn 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 UV–Vis 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 Mn–Zn ferrite.

Laohhasurayotin, Kritapas, E-mail: kritapas@nanotec.or.th [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand); Pookboonmee, Sudarat; Viboonratanasri, Duangkamon; Kangwansupamonkon, Wiyong [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)] [National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Rd., Klong 1, Klong Luang, Patumthani 12120 (Thailand)

2012-06-15T23:59:59.000Z

407

Aqueous NaCl and CsCl Solutions Confined in Crystalline Slit-Shaped Silica Nanopores of Varying Degrees of Protonation  

SciTech Connect (OSTI)

All-atom molecular dynamics simulations were conducted to study the dynamics of aqueous electrolyte solutions confined in slit-shaped silica nanopores of various degrees of protonation. Five degrees of protonation were prepared by randomly removing surface hydrogen atoms from fully protonated crystalline silica surfaces. Aqueous electrolyte solutions containing NaCl or CsCl salt were simulated at ambient conditions. In all cases, the ionic concentration was 1 M. The results were quantified in terms of atomic density distributions within the pores, and the self-diffusion coefficient along the direction parallel to the pore surface. We found evidence for ion-specific properties that depend on ion surface, water ion, and only in some cases ion ion correlations. The degree of protonation strongly affects the structure, distribution, and the dynamic behavior of confined water and electrolytes. Cl ions adsorb on the surface at large degrees of protonation, and their behavior does not depend significantly on the cation type (either Na+ or Cs+ ions are present in the systems considered). The cations show significant ion-specific behavior. Na+ ions occupy different positions within the pore as the degree of protonation changes, while Cs+ ions mainly remain near the pore center at all conditions considered. For a given degree of protonation, the planar self-diffusion coefficient of Cs+ is always greater than that of Na+ ions. The results are useful for better understanding transport under confinement, including brine behavior in the subsurface, with important applications such as environmental remediation.

Ho, Thomas [ORNL; Argyris, Dr. Dimitrios [University of Oklahoma; Cole, David [Ohio State University; Striolo, Alberto [Oklahoma University

2012-01-01T23:59:59.000Z

408

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

SciTech Connect (OSTI)

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.

Waslylenko, Walter; Frei, Heinz

2007-01-31T23:59:59.000Z

409

Kinetics of Silica Polymerization  

E-Print Network [OSTI]

G. E Tardiff, "The LLL Geothermal Energy Program St s Reportmal Effluent Inj ection", Geothermal Energy Novelty Becomesfor Injection", Geothermal Energy Novelty Becomes Resource:

Weres, Oleh

2011-01-01T23:59:59.000Z

410

Kinetics of Silica Polymerization  

E-Print Network [OSTI]

by the value of parameter IPR, which has a default value oft L I Specifying values of IPR in the range 1 6 will causethat described above the value'of IPR causes the gene ion of

Weres, Oleh

2011-01-01T23:59:59.000Z

411

Preparation of silica aerogel using ionic liquids as solvents Sheng Dai,*a Y. H. Ju,ac H. J. Gao,b J. S. Lin,b S. J. Pennycookb and C. E. Barnesc  

E-Print Network [OSTI]

Preparation of silica aerogel using ionic liquids as solvents Sheng Dai,*a Y. H. Ju,ac H. J. Gaord December 1999 Ionic liquids have been used as effective solvents to synthesize aerogels; a long aging time can be used to produce stable aerogel structures without the need for supercritical drying

Gao, Hongjun

412

Results of investigation at the Miravalles geothermal field, Costa Rica. Resultados de las investigaciones en el campo geotermico de Miravalles, Costa Rica; Parte 2, Muestreo de fluidos pozo abajo  

SciTech Connect (OSTI)

Samples of the geothermal fluids in the Miravalles, Costa Rica, geothermal system were collected from production wellbores using downhole fluid samplers, from flowing wellheads using miniseparators, and from hot springs that discharge in the area. The reservoir fluid at Miravalles is a neutral-chloride-type water, but fumaroles and acid-sulfate springs are present within the main thermal area, and there are bicarbonate-rich hot springs that are clearly related to the neutral-chloride reservoir fluids. Dissolved gases are primarily a mixture of CO{sub 2} with air, but samples collected in the fumarolic areas also contain H{sub 2}S. Water-stable isotope analyses suggest local meteoric recharge, and the reservoir fluid shows oxygen isotopic shifts of about 2.5% due to high-temperature oxygen exchange between water and rock. Chemical geothermometer temperatures are consistent with the measured downhole temperature of 220{degrees} to 255{degrees}C. This pattern of neutral-chloride reservoir fluids with acid-sulfate springs near the source region and bicarbonate-rich chloride hot springs at the periphery of the system suggests a lateral outflow type of hydrothermal system. In addition to the geochemical evidence, temperature profiles from several of the wells show temperature reversals that are characteristic of lateral outflow plumes. We find no evidence for the underlying, higher temperature (300{degrees}C) system, which has been suggested by other investigators. 24 refs., 14 figs., 6 tabs.

Grigsby, C.O.; Goff, F.; Trujillo, P.E. Jr.; Counce, D.A.; Dennis, B.; Kolar, J.; Corrales, R. (Los Alamos National Lab., NM (USA); Instituto Costarricense de Electricidad, San Jose (Costa Rica))

1989-10-01T23:59:59.000Z

413

Water information bulletin No. 30 geothermal investigations in Idaho  

SciTech Connect (OSTI)

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.

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

1980-06-01T23:59:59.000Z

414

BACA Project: geothermal demonstration power plant. Final report  

SciTech Connect (OSTI)

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.

Not Available

1982-12-01T23:59:59.000Z

415

Time-resolved x-ray imaging of high-power laser-irradiated under-dense silica aerogels and agar foams  

SciTech Connect (OSTI)

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.

Koch, J.A.; Estabrook, K.G.; Bauer, J.D. [and others

1995-08-01T23:59:59.000Z

416

Numerical simulation study of silica and calcite dissolution around a geothermal well by injecting high pH solutions with chelating agent.  

SciTech Connect (OSTI)

Dissolution of silica, silicate, and calcite minerals in the presence of a chelating agent (NTA) at a high pH has been successfully performed in the laboratory using a high-temperature flow reactor. The mineral dissolution and porosity enhancement in the laboratory experiment has been reproduced by reactive transport simulation using TOUGHREACT. The chemical stimulation method has been applied by numerical modeling to a field geothermal injection well system, to investigate its effectiveness. Parameters from the quartz monzodiorite unit at the Enhanced Geothermal System (EGS) site at Desert Peak (Nevada) were used. Results indicate that the injection of a high pH chelating solution results in dissolution of both calcite and plagioclase minerals, and avoids precipitation of calcite at high temperature conditions. Consequently reservoir porosity and permeability can be enhanced especially near the injection well.

Xu, Tianfu; Rose, Peter; Fayer, Scott; Pruess, Karsten

2009-02-01T23:59:59.000Z

417

The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces  

SciTech Connect (OSTI)

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.

Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W

2009-10-29T23:59:59.000Z

418

PMo or PW heteropoly acids supported on MCM-41 silica nanoparticles: Characterisation and FT-IR study of the adsorption of 2-butanol  

SciTech Connect (OSTI)

Mesoporous silica, prepared in basic conditions, has been loaded (20% weight) with 12-molybdophosphoric (PMo) or 12-tungstophosphoric (PW) acid and calcined at different temperatures ranging between 250 and 550 deg. C. The samples have been characterised by N{sub 2} adsorption-desorption at -196 deg. C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), UV-visible diffuse reflectance, Raman spectroscopy and temperature programmed reduction (TPR). The acidity and catalytic activity have been, respectively, examined by monitoring the adsorption of pyridine and 2-butanol by FT-IR spectroscopy. The results indicate that PW and PMo acids are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles. While PMo retains its Keggin structure up to 550 deg. C, PW decomposes at this temperature into crystalline WO{sub 3} and phosphorous oxides. In both cases, the morphology, hexagonal symmetry and long-range order observed for the support are preserved with calcination up to 450 deg. C. The Broensted-type acid sites found in all samples, whose surface concentration decreases as the calcination temperature increases, are responsible for the selective formation of cis-butene detected upon adsorption of 2-butanol. The sample containing PW calcined at 450 deg. C also shows selectivity to methyl ethyl ketone. - Graphical abstract: Samples based in MCM-41 nanoparticles loaded with tungstophosphoric and molybdophosphoric acids have been synthesised. The uncalcined solids and that derived upon their calcination in the temperature range 250-550 deg. C have been characterised and evaluated in the decomposition of 2-butanol monitored by FT-IR spectroscopy.

Carriazo, Daniel [GIR-QUESCAT, Dpto. de Quimica Inorganica, Universidad de Salamanca, 37008-Salamanca (Spain); Domingo, Concepcion [Instituto de Estructura de la Materia, C.S.I.C., Serrano, 123, 28006-Madrid (Spain); Martin, Cristina [GIR-QUESCAT, Dpto. de Quimica Inorganica, Universidad de Salamanca, 37008-Salamanca (Spain); Rives, Vicente [GIR-QUESCAT, Dpto. de Quimica Inorganica, Universidad de Salamanca, 37008-Salamanca (Spain)], E-mail: vrives@usal.es

2008-08-15T23:59:59.000Z

419

In-situ Spectroscopy of Water Oxidation at Ir Oxide Nanocluster Drivenby Visible TiOCr Charge-Transfer Chromophore in Mesoporous Silica  

SciTech Connect (OSTI)

An all-inorganic photocatalytic unit consisting of a binuclear TiOCr charge-transfer chromophore coupled to an Ir oxide nanocluster has been assembled on the pore surface of mesoporous silica AlMCM-41. In situ FT-Raman and EPR spectroscopy of an aqueous suspension of the resulting IrxOy-TiCr-AlMCM-41 powder reveal the formation of superoxide species when exciting the Ti(IV)OCr(III) --> Ti(III)OCr(IV) metal-to-metal charge-transfer chromophore with visible light. Use of H218O confirms that the superoxide species originates from oxidation of water. Photolysis in the absence of persulfate acceptor leads to accumulation of Ti(III) instead. The results are explained by photocatalytic oxidation of water at Ir oxide nanoclusters followed by trapping of the evolving O2 by transient Ti(III) centers to yield superoxide. Given the flexibility to select donor metals with appropriate redox potential, photocatalytic units consisting of a binuclear charge-transfer chromophore coupled to a water oxidation catalyst shown here constitute a step towards thermodynamically efficient visible light water oxidation units.

Frei, Heinz; Han, Hongxian; Frei, Heinz

2008-06-03T23:59:59.000Z

420

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)

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.

Henghu Sun; Yuan Yao

2012-06-29T23:59:59.000Z

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Influence of the pressure on the properties of chromatographic columns I. Measurement of the compressibility of methanol-water mixtures on a mesoporous silica adsorbent  

SciTech Connect (OSTI)

The compressibilities of aqueous solutions of methanol or acetonitrile containing 0, 20, 40, 60, 80 and 100% (v/v) organic solvent were measured with a dynamic chromatographic method. The elution volumes of thiourea samples (2 {micro} L) in these solutions were measured at different average column pressures, adjusted by placing suitable capillary restrictors on-line, after the detector. The reproducibility of the measurements was better than 0.2%. In the range of average pressures studied (10-350 bar), the maximum change in elution volume of thiourea is 1.3% (in pure water) and 4.0% (in pure methanol). This difference is due to the different compressibilities of these pure solvents. For mixtures, the plots of the elution volume of thiourea versus the pressure are convex downward, which is inconsistent with the opposite curvature predicted by the classical Tait model of liquid compressibility. This difference is explained by the variation of the amount of thiourea adsorbed with the pressure. The deconvolution of the two effects, adsorption of thiourea and solvent compressibility, allows a fair and consistent determination of the compressibilities of the methanol-water mixtures. A column packed with non-porous silica particles was also used to determine the compressibility of methanol-water and acetonitrile-water mixtures. A negative deviation by respect to ideal behavior was observed.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

2005-03-01T23:59:59.000Z

422

Influence of the pressure on the properties of chromatographic columns I. Measurement of the compressibility of methanol-water mixtures on a mesoporous silica adsorbent  

SciTech Connect (OSTI)

The compressibilities of aqueous solutions of methanol or acetonitrile containing 0, 20, 40, 60, 80 and 100% (v/v) organic solvent were measured with a dynamic chromatographic method. The elution volumes of thiourea samples (2 {micro} L) in these solutions were measured at different average column pressures, adjusted by placing suitable capillary restrictors on-line, after the detector. The reproducibility of the measurements was better than 0.2%. In the range of average pressures studied (10-350 bar), the maximum change in elution volume of thiourea is 1.3% (in pure water) and 4.0% (in pure methanol). This difference is due to the different compressibilities of these pure solvents. For mixtures, the plots of the elution volume of thiourea versus the pressure are convex downward, which is inconsistent with the opposite curvature predicted by the classical Tait model of liquid compressibility. This difference is explained by the variation of the amount of thiourea adsorbed with the pressure. The deconvolution of the two effects, adsorption of thiourea and solvent compressibility, allows a fair and consistent determination of the compressibilities of the methanol-water mixtures. A column packed with non-porous silica particles was also used to determine the compressibility of methanol-water and acetonitrile-water mixtures. A negative deviation by respect to ideal behavior was observed.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

2005-04-01T23:59:59.000Z

423

SIZE AND DENSITY ESTIMATION FROM IMPACT TRACK MORPHOLOGY IN SILICA AEROGEL: APPLICATION TO DUST FROM COMET 81P/WILD 2  

SciTech Connect (OSTI)

A large number of cometary dust particles were captured with low-density silica aerogel during the NASA Stardust mission. The dust particles penetrated into the aerogel and formed various track shapes. To estimate the properties of the dust particles, such as density and size, based on the morphology of the tracks, we carried out systematic experiments testing impacts into low-density aerogel at 6 km s{sup -1} using projectiles of various sizes and densities. We found that the maximum track diameter and the ratio of the track length to the maximum track diameter in aerogel are good indicators of projectile size and density, respectively. Based on these results, we estimated the size and density of individual dust particles from comet 81P/Wild 2. The average density of the 'fluffy' dust particles and the bulk density of all dust particles were obtained as 0.35 {+-} 0.07 and 0.49 {+-} 0.18 g cm{sup -3}, respectively. These statistical data provided the content of monolithic and coarse grains in the Stardust particles, {approx}30 wt%. Combining this result with some mid-infrared observational data, we found that the content of crystalline silicates is {approx}50 wt% or more of non-volatile material.

Niimi, Rei; Tsuchiyama, Akira [Department of Earth and Space Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Kadono, Toshihiko [Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Okudaira, Kyoko [Office for Planning and Management, The University of Aizu, Aizuwakamatsu, Fukushima 965-8580 (Japan); Hasegawa, Sunao; Tabata, Makoto [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252-5210 (Japan); Watanabe, Takayuki; Yagishita, Masahito [Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, Nagatsuta, Yokohama 226-8502 (Japan); Machii, Nagisa; Nakamura, Akiko M. [Department of Earth and Planetary Sciences, Kobe University, Nada, Kobe 657-8501 (Japan); Uesugi, Kentaro; Takeuchi, Akihisa [Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo 679-5198 (Japan); Nakano, Tsukasa, E-mail: kadonot@ile.osaka-u.ac.jp [Geological Survey of Japan, Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8567 (Japan)

2012-01-01T23:59:59.000Z

424

Enhanced Gas Absorption in the Ionic Liquid 1-n-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide ([hmim][Tf{sub 2}N]) Confined in Silica Slit Pores: A Molecular Simulation Study  

SciTech Connect (OSTI)

Two-dimensional NP{sub xy}T and isostress-osmotic (N{sub 2}P{sub xy}Tf{sub 1}) Monte Carlo simulations were used to compute the density and gas absorption properties of the ionic liquid (IL) 1-n-hexyl-3- methylimidazolium bis(Trifluoromethylsulfonyl)amide ([hmim][Tf{sub 2}N]) confined in silica slit pores (25-45 Å). Self-diffusivity values for both gas and IL were calculated from NVE molecular dynamics simulations using both smooth and atomistic potential models for the silica. Simulations show that the molar volume for [hmim][Tf{sub 2}N] confined in 25-45 Å silica slit pores are 12-31% larger than for the bulk IL at 313-573 K and 1 bar. The amounts of CO{sub 2}, H{sub 2}, and N{sub 2} absorbed in the confined IL are typically 1.1-3 times larger than in the bulk IL due to larger molar volumes for the confined IL compared to the bulk IL. The CO{sub 2}, N{sub 2}, and H{sub 2} molecules are generally absorbed close to the silica wall where the IL density is very low. This arrangement causes the self-diffusivities for these gases in the confined IL to be 2 to 8 times larger than in the bulk IL at 298-573 K. The solubility for water in the confined and bulk ILs are similar, which is likely due to strong water interactions with [hmim][Tf{sub 2}N] through hydrogen-bonding resulting in the confined IL molar volume playing a less important role in determining H{sub 2}O solubility. Water molecules were largely absorbed in the IL-rich region rather than close to the silica wall. The self-diffusivities for water correlate with the confined IL. The confined IL exhibits self-diffusivities larger than the bulk IL at lower temperatures, but smaller than the bulk IL at higher temperatures. The findings from simulations are consistent with available experimental data for similar confined IL systems.

Shi, Wei; Luebke, David R.

2013-05-07T23:59:59.000Z

425

Phase transition upon K{sup +} ion exchange into Na-low silica X: Combined NMR and synchrotron X-ray powder diffraction study  

SciTech Connect (OSTI)

The mechanism by which K{sup +} ions exchange into zeolite Na-low silica X (LSX) (Na{sub 96}Al{sub 96}Si{sub 96}O{sub 384}{center_dot}nH{sub 2}O) has ben determined by studying structures of the Na-LSX and K-LSX end members in the Na-K LSX solid solution series as well as samples exchanged at the 20%, 42% and 80% K{sup +} levels. A preliminary investigation using {sup 29}Si MAS NMR spectroscopy revealed a two-phase region in the solid solution near 80% K{sup +} exchange. Rietveld analysis of the powder diffraction data collected from hydrated samples showed that, up to 42% of K{sup +} exchange, K{sup +} ions were located preferentially at site I{prime}, just outside the double 6-ring (D6R) in the sodalite age, and at site II, above the single 6-ring (S6R) in the supercage. Introduction of K{sup +} ions into site I{prime} repositioned Na{sup +} ions into site I, at the center of the D6R. An abrupt change in the cubic lattice parameter from 25.0389(5) to 25.2086(5) {angstrom} marked the formation of a second phase at the 80% K{sup +}-exchange level as K{sup +} ions began to occupy site I. No coexistence of phases was observed for the fully K{sup +}-exchanged sample (a = 25.2486(2) {angstrom}), where sites I and II were fully occupied by K{sup +} ions.

Lee, Y.; Parise, J.B. [State Univ. of New York, Stony Brook, NY (United States)] [State Univ. of New York, Stony Brook, NY (United States); Carr, S.W. [ANSTO, Menai (Australia)] [ANSTO, Menai (Australia)

1998-09-01T23:59:59.000Z

426

Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica  

SciTech Connect (OSTI)

A comparative study of catalytic activity under homogeneous and heterogeneous conditions was carried out using the (salen)Cr{sup III}-catalyzed oxidation of tetramethylbenzidine (TMB) with iodosobenzene as a model reaction. Amine-functionalized mesoporous silica nanoparticles (MSN) were synthesized in a co-condensation reaction and functionalized with salen via a covalent Si-C bond. A Cr(III) complex of this supported ligand, MSN-(salen)Cr{sup III}, was prepared and characterized. Data from powder XRD, BET isotherms and BJH pore size distribution all showed that MSN-(salen)Cr{sup III} still had the typical MSN high surface area, narrow pore size distribution, and ordered hexagonal pore structure, which were further confirmed by transmission electron microscopy (TEM) images. {sup 13}C and {sup 29}Si solid-state NMR data provided structural information about the catalyst and verified successful functionalization of the salen ligand and coordination to Cr(III). No unreacted salen or Cr(III) were observed. The loadings of salen and salen-Cr{sup III} complex were determined via TGA and EDX, respectively. Both measurements indicated that approximately 0.5 mmol/g of catalyst was loaded on the surface of MSN. The oxidation of TMB with iodosobenzene using MSN-(salen)Cr{sup III} as a heterogeneous catalyst exhibited both similarities and differences with the analogous homogeneous reaction using (salen)Cr{sup III}(H{sub 2}O){sup +} as a catalyst in aqueous acetonitrile. In the presence of 0.10 M HClO{sub 4}, the two catalytic reactions proceeded at similar rates and generated the doubly oxidized product TMB{sup 2+}. In the absence of acid, the radical cation TMB{sup +} was produced. The kinetics of the heterogeneous reaction in the absence of added acid responded to concentrations of all three reagents, i.e. (salen)Cr{sup III}, TMB, and PhIO.

Szajna-Fuller, Ewa; Huang, Yulin; Rapp, Jennifer L.; Chaka, Gezhegn; Lin, Victor S.Y.; Pruski, Marek; Bakac, Andreja

2009-03-09T23:59:59.000Z

427

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)

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.

Andersson, Gunther G., E-mail: gunther.andersson@flinders.edu.au, E-mail: vladimir.golovko@canterbury.ac.nz, E-mail: greg.metha@adelaide.edu.au; Al Qahtani, Hassan S. [Flinders Centre for NanoScale Science and Technology, Flinders University, Adelaide SA 5001 (Australia); Golovko, Vladimir B., E-mail: gunther.andersson@flinders.edu.au, E-mail: vladimir.golovko@canterbury.ac.nz, E-mail: greg.metha@adelaide.edu.au [Flinders Centre for NanoScale Science and Technology, Flinders University, Adelaide SA 5001 (Australia); The MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Christchurch 8140 (New Zealand); Alvino, Jason F.; Bennett, Trystan; Wrede, Oliver; Mejia, Sol M.; Metha, Gregory F., E-mail: gunther.andersson@flinders.edu.au, E-mail: vladimir.golovko@canterbury.ac.nz, E-mail: greg.metha@adelaide.edu.au [Department of Chemistry, University of Adelaide, Adelaide SA 5005 (Australia); Adnan, Rohul [The MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Christchurch 8140 (New Zealand); Chemistry Department, University of Malaya, 50603 Kuala Lumpur (Malaysia); Gunby, Nathaniel; Anderson, David P. [The MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Christchurch 8140 (New Zealand)

2014-07-07T23:59:59.000Z

428

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)

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.

Seright, R.S.; Martin, F.D.

1992-09-01T23:59:59.000Z

429

Silica Deposition | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty Ltd Jump to: navigation,Pvt LtdShrub Oak, New York:Siemens°SilescentDeposition

430

Mixed-Matric Membranes for CO2 and H2 Gas Separations Using Metal-Organic Framework and Mesoporus Hybrid Silicas  

SciTech Connect (OSTI)

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.

Inga Musselman; Kenneth Balkus, Jr.; John Ferraris

2009-01-07T23:59:59.000Z

431

Solid state reactions of nanocrystalline Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75} mixed oxide with high surface area silica in oxidizing and reducing atmosphere  

SciTech Connect (OSTI)

The interaction of nanocrystalline Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75} mixed oxide with a high surface amorphous silica support in an oxidizing and reducing atmosphere was studied by XRD, HRTEM, SAED, SEM and BET techniques. The Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75}-SiO{sub 2} system shows very high structural and size stability in the oxidizing atmosphere up to 1000 Degree-Sign C, but in hydrogen spreading of the oxide onto silica occurs at temperatures above 800 Degree-Sign C. In the oxidizing atmosphere stability of the mixed oxide is limited by extraction of ytterbium from the oxide driven by a tendency to form ytterbium silicates. A new polymorph of Yb silicate, isomorphic with y-Y{sub 2}Si{sub 2}O{sub 7} (yttrialite), has been identified in the samples containing the mixed Ce-Yb oxide. The absence of y-Yb{sub 2}Si{sub 2}O{sub 7} silicate in the Yb{sub 2}O{sub 3}-SiO{sub 2} samples treated in similar conditions indicates that Ce{sup 4+} ions are needed to stabilize the structure. - Graphical abstract: Structure evolution of nano-Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75}-SiO{sub 2} in air and in H{sub 2}. Highlights: Black-Right-Pointing-Pointer Nano-Ce{sub 0.50}Yb{sub 0.50}O{sub 1.75} on SiO{sub 2} is stable in air up to 1000 Degree-Sign C but spreads in hydrogen at 800 Degree-Sign C. Black-Right-Pointing-Pointer Formation of Yb silicates determines the stability of Ce{sub 0.50}Yb{sub 0.50}O{sub 1.75} at high temperatures. Black-Right-Pointing-Pointer New, y-Yb{sub 2}Si{sub 2}O{sub 7} silicate (yttrialite type) forms in Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75}-SiO{sub 2} in H{sub 2} at 1100 Degree-Sign C.

Malecka, Malgorzata A. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2 (Poland); Kepinski, Leszek, E-mail: L.Kepinski@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2 (Poland)

2012-08-15T23:59:59.000Z

432

Modeling of optical amplifier waveguide based on silicon nanostructures and rare earth ions doped silica matrix gain media by a finite-difference time-domain method: comparison of achievable gain with Er3+ or Nd3+ ions dopants  

E-Print Network [OSTI]

A comparative study of the gain achievement is performed in a waveguide optical amplifier whose active layer is constituted by a silica matrix containing silicon nanograins acting as sensitizer of either neodymium ions (Nd 3+) or erbium ions (Er 3+). Due to the large difference between population levels characteristic times (ms) and finite-difference time step (10 --17 s), the conventional auxiliary differential equation and finite-difference time-domain (ADE-FDTD) method is not appropriate to treat such systems. Consequently, a new two loops algorithm based on ADE-FDTD method is presented in order to model this waveguide optical amplifier. We investigate the steady states regime of both rare earth ions and silicon nanograins levels populations as well as the electromagnetic field for different pumping powers ranging from 1 to 10 4 mW.mm-2. Furthermore, the three dimensional distribution of achievable gain per unit length has been estimated in this pumping range. The Nd 3+ doped waveguide shows a higher gross...

Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice

2015-01-01T23:59:59.000Z

433

Enhanced Specific Heat of Silica Donghyun Shin  

E-Print Network [OSTI]

, molten salt, lithium carbonate, potassium carbonate, solar energy, thermal en- ergy storage, phase change the operational efficiencies and reliability of solar thermal energy conversion systems. The materials material 1 Introduction Thermal energy storage TES systems at high temperatures are required to improve

Banerjee, Debjyoti

434

Deformation of Silica Aerogel During Fluid Adsorption  

E-Print Network [OSTI]

Aerogels are very compliant materials - even small stresses can lead to large deformations. In this paper we present measurements of the linear deformation of high porosity aerogels during adsorption of low surface tension fluids, performed using a Linear Variable Differential Transformer (LVDT). We show that the degree of deformation of the aerogel during capillary condensation scales with the surface tension, and extract the bulk modulus of the gel from the data. Furthermore we suggest limits on safe temperatures for filling and emptying low density aerogels with helium.

Tobias Herman; James Day; John Beamish

2005-06-30T23:59:59.000Z

435

Manufacturing complex silica aerogel target components  

SciTech Connect (OSTI)

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.

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

2008-01-01T23:59:59.000Z

436

CHEMISTRY OF SILICA IN CERRO PRIETO BRINES  

E-Print Network [OSTI]

lfuen operated w:l.thout sludge recirculation, this pilotcould lead to problems with sludge accumulation there. Ifby recirculation of part of the sludge coming out of the

Weres, O.

2012-01-01T23:59:59.000Z

437

Sandia National Laboratories: hardened silica structure  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1development Sandia,evaluatingfull moduleresources grid integration

438

Iron(III)-doped, silica : biodegradable, self-targeting nanoparticles  

E-Print Network [OSTI]

1: Scientific Thinking and Nanoscience The first activity (1: Scientific Thinking and Nanoscience) developed focused on1: Scientific Thinking and Nanoscience Scientific Thinking &

Mitchell, Kristina Kalani Pohaku

2011-01-01T23:59:59.000Z

439

Giant Magnetoresistive Phosphoric Acid Doped Polyaniline-Silica Nanocomposites  

E-Print Network [OSTI]

including sensors,13 electrochemical mechanical actuators,14 electrochromic supercapacitors,15 and flexible the inkjet-printing electrochromic de

Guo, John Zhanhu

440

ORIGINAL ARTICLE Extended release of adenovirus from silica implants  

E-Print Network [OSTI]

Program and Transplantation Laboratory, University of Helsinki, Helsinki, Finland; 2 HUSLAB, Helsinki University Central Hospital, Helsinki, Finland; 3 DelsiTech Ltd, Turku, Finland; 4 Turku Center for Biomaterials, University of Turku, Finland; 5 Department of Dermatology, University of Turku, Turku, Finland; 6

Hemminki, Akseli

Note: This page contains sample records for the topic "geothermometers silica geothermometers" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

High-silica zeolite nucleation from clear solutions  

E-Print Network [OSTI]

Understanding the mechanism of zeolite nucleation and crystallization will enable the zeolite science community to tune zeolite properties during synthesis in order to accommodate the purposes of various applications. Thus there has been...

Cheng, Chil-Hung

2006-04-12T23:59:59.000Z

442

SnOx Nanocrystallites Supported by Silica Nanostructures  

E-Print Network [OSTI]

, it has been possible to reduce a Ni(III) solution in an electroless process on the surface of the nanospheres producing a ferromagnetic crystalline nickel coating6 of variable thickness. These results.g., nickel, silver), as they result from ex-situ processes, does not lend itself readily to the creation

Wang, Zhong L.

443

Silica lipid composite microparticles as controlled release system  

E-Print Network [OSTI]

and high ionic strength (NaCl 0.1M), using a turbine Ika Eurostar (IKA® Werke GmbH & Co. KG, Germany), with a 3-blade Teflon® propeller at 750 rpm. Microparticles were obtained by cooling the hot emulsion at 20

Paris-Sud XI, Université de

444

Molecular Dynamic Study of Thermal Conductivity of Amorphous Nanoporous Silica  

E-Print Network [OSTI]

as a thermal isolation layer”. Ceramics International, 34(Thermal conductivity of highly porous zirconia”. Journal of the European Ceramic

Coquil, Thomas; Fang, Jin; Pilon, Laurent

2011-01-01T23:59:59.000Z

445

Incorporation of silica into baroplastic core-shell nanoparticles  

E-Print Network [OSTI]

Core-shell baroplastics are nanophase materials that exhibit pressure-induced flow at low temperatures and high pressures. Core-shell baroplastics used in this work are comprised of a low Tg poly(butyl acrylate) (PBA) core ...

Hewlett, Sheldon A

2006-01-01T23:59:59.000Z

446

Graphene-Silica Composite Thin Films as Transparent Conductors  

E-Print Network [OSTI]

as fillers for a broad range of composite materials. Attempts to exfoliate graphene-based sheets by intercalation of graphite with potassium metal have been discussed;34 however, the exfoliated nanoplatelets oxide-based sheets35,36 produced by complete exfoliation of graphite oxide (GO) as an entry

447

Fluorescent single walled nanotube/silica composite materials  

DOE Patents [OSTI]

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.

Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

2013-03-12T23:59:59.000Z

448

Compressed Silica Aerogels for the Study of Superfluid 3He  

SciTech Connect (OSTI)

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.

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)

2006-09-07T23:59:59.000Z

449

SAXS and USAXS-characterization of granular silica aerogels  

E-Print Network [OSTI]

thus optical appearance four different types of aerogel granulates were characterized using SAXS and

M. Reim; G. Reichenauer; R. Br; C. Schmitt; T. Schliermann; W. Körner; J. Fricke

450

Methods for globally treating silica optics to reduce optical damage  

DOE Patents [OSTI]

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.

Miller, Philip Edward; Suratwala, Tayyab Ishaq; Bude, Jeffrey Devin; Shen, Nan; Steele, William Augustus; Laurence, Ted Alfred; Feit, Michael Dennis; Wong, Lana Louie

2012-11-20T23:59:59.000Z

451

Iron(III)-doped, silica : biodegradable, self-targeting nanoparticles  

E-Print Network [OSTI]

of calcium and phosphorous, which can be attributed toamount of calcium and phosphorous increase. The iron(III)-composed of calcium and phosphorous were in the recovered

Mitchell, Kristina Kalani Pohaku

2011-01-01T23:59:59.000Z

452

alkali silica reactions: Topics by E-print Network  

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

method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile...

453

active silica derived: Topics by E-print Network  

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

method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile...

454

alkyl silica microcolumn: Topics by E-print Network  

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

method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile...

455

alkali silica reaction: Topics by E-print Network  

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

method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile...

456

amorphous silica particles: Topics by E-print Network  

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

Self the material the ability to heal after a damage event. An early example of a self-healing polymeric system Braun, Paul 26 Synthesis and postmodification of...

457

amorphous silica nanoparticles: Topics by E-print Network  

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

arrays of metal nanoparticles hold great promise for many applications.1 The successful synthesis Kim, Sehun 6 PHYSICAL REVIEW B 89, 144303 (2014) Thermal conductivity...

458

amorphous silica probed: Topics by E-print Network  

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

for which a smooth surface is important, such as optical windows, X-ray masks, SAW filters and other electronic devices. Mechanical lapping and polishing techniques are...

459

Technical Note Viscoelastic Behavior of Silica Particle Compacts  

E-Print Network [OSTI]

to the noise emitted by trains, particularly high-speed trains. How soil is affected by dynamic mechanical Lu1 and D. D. L. Chung2 Abstract: The viscoelastic behavior of model sandy soils in the form is recommended for mechanical energy dissipation. DOI: 10.1061/(ASCE)MT.1943-5533.0000831. © 2014 American

Chung, Deborah D.L.

460

Silica Fume as a Radon Retardant from Concrete  

E-Print Network [OSTI]

, and tracheobronchial deposition of radon progeny can lead to lung cancers. Aggregates (granite) are known-made indoor environments, mainly due to poor ventilation. Radon decays to form radon progeny. While most of the radon gas inhaled will be exhaled, the radon progeny will adhere to the respiratory tract. It is now

Yu, K.N.

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461

Functionalized Nanoporous Silica for Removal of Heavy Metals...  

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

(SAMMS) have previously demonstrated the ability to serve as very effective heavy metal sorbents in a range of aquatic and environmental systems suggesting they may be...