19 Search Results

In Yoshii et al., we described a new method for measuring extragalactic distances based on dust reverberation in active galactic nuclei (AGNs), and we validated our new method with Cepheid variable stars. In this Letter, we validate our new method with Type Ia supernovae (SNe Ia) that occurred in two of the AGN host galaxies during our AGN monitoring program: SN 2004bd in NGC 3786 and SN 2008ec in NGC 7469. Their multicolor light curves were observed and analyzed using two widely accepted methods for measuring SN distances, and the distance moduli derived are μ=33.47±0.15 for SN 2004bd and 33.83 ± 0.07more » for SN 2008ec. These results are used to obtain independently the distance measurement calibration factor, g. The g value obtained from the SN Ia discussed in this Letter is g{sub SN}=10.61±0.50, which matches, within the range of 1σ uncertainty, g{sub DUST}=10.60, previously calculated ab initio in Yoshii et al. Having validated our new method for measuring extragalactic distances, we use our new method to calibrate reverberation distances derived from variations of Hβ emission in the AGN broad-line region, extending the Hubble diagram to z≈0.3 where distinguishing between cosmologies is becoming possible.« less

Annotated whole genome sequences of three isolates of the Akhmeta virus (AKMV), a novel species of orthopoxvirus (OPXV), isolated from the Akhmeta and Vani regions of the country Georgia, are presented and discussed. The AKMV genome is similar in genomic content and structure to that of the cowpox virus (CPXV), but a lower sequence identity was found between AKMV and Old World OPXVs than between other known species of Old World OPXVs. Phylogenetic analysis showed that AKMV diverged prior to other Old World OPXV. AKMV isolates formed a monophyletic clade in the OPXV phylogeny, yet the sequence variability between AKMVmore » isolates was higher than between the monkeypox virus strains in the Congo basin and West Africa. An AKMV isolate from Vani contained approximately six kb sequence in the left terminal region that shared a higher similarity with CPXV than with other AKMV isolates, whereas the rest of the genome was most similar to AKMV, suggesting recombination between AKMV and CPXV in a region containing several host range and virulence genes.« less

The photoluminescence of a dye embedded in the three-dimensional SnS{sub 2} inverted opal has been studied. Changes of the emission spectrum compared with the free-space dye emission was observed in the stop-band frequency range in accord with reflectance/transmission spectra of this photonic crystal. The angular-dependent component, due to the Bragg stop band, and the angular-independent component, which is, possibly, related to the minimum in the density of photon states, have been distinguished in the dye emission spectrum. {copyright} 2001 American Institute of Physics.

The objective of this research program is to determine the feasibility of the alga Botryococcus braunii as a biocatalyst for the photosynthetic conversion of flue gas CO{sub 2} to hydrocarbons. Free and immobilized cells of Botryococcus braunii were grown in aqueous medium supplemented with nitrogen, phosphorus and mineral nutrients. Air and CO{sub 2} enriched air [10% to 15% (V/V) CO{sub 2}] in the gas phase and 0.2% to 2% NaHCO{sub 3} in the liquid medium served as the carbon source. Growth and hydrocarbon formation characteristics of free and immobilized cultures of Botryococcus braunii were determined in bench-scale photobioreactors. Technical andmore » economic feasibility of the conversion of flue gas CO{sub 2} to hydrocarbons by Botryococcus braunii culture systems was evaluated. In free cell systems, the hexane extractable oil productivity was about 15 to 37 grams of oil per 100 grams of cell dry weight. In immobilized cell systems, the oil production ranged between 5% and 47% at different immobilization systems and immobilized surface locations, with an average of 19% of cell biomass dry weight. The feasibility and economic evaluation estimated the cost of oil produced from flue gas CO{sub 2} by algae to range between $45 and $75 per barrel assuming that a hydrocarbon yield of about 50% of the biomass weight is achievable and a credit of $60 per ton of carbon removed is available. A future research program leading to development of a multistage process, consisting of closed systems for heavy inoculum buildup followed by lower cost open systems for oil production is recommended.« less

A study was conducted on the effects of pH of the medium, composition of Fenton's reagent, and the effect of soil's preequilibration with the chemical, on the degradation of [sup 14]C-labeled free and complex cyanide in aqueous and soil-containing systems. The application of Fenton's reagent resulted in degradation of 80% and 67% of potassium cyanide in aqueous systems at pH 7.2 and 10.0, respectively. No appreciable amount of K[sub 4][Fe(CN)[sub 6]] was degraded at either pH tested. Under the alkaline condition, negligible amounts of cyanide were converted to HCN and were removed from liquid phase due to precipitation. In themore » soil systems containing uncontaminated topsoil or manufactured gas plant (MGP) soil, both freshly amended with free cyanide, 80% of the compound was degraded by the Fenton's reagent of the same composition. Similar to the aqueous systems, no complex cyanide was degraded in soil slurries. In both soils, previously equilibrated with free and complex cyanides, the extent of degradation caused by Fenton's reagent was not more than 6% at either pH. However, at alkaline pH, up to 21% of previously added complex cyanide was leached out into a liquid phase where it could be further degraded. The optimum composition of Fenton's reagent under alkaline pH was found to b3 1% of H[sub 2]O[sub 2] and 1 mM FeSO[sub 4]. The authors suggest that the application of Fenton's reagent under alkaline conditions may be useful in a combined physicochemical treatment for the remediation of sites contaminated with cyanides.« less

The studies reported here confirmed our preliminary observations that Botryococcus braunii can tolerate and grow well in flue gas CO{sub 2} concentrations of 10 to 15%, and produce oil. The highest extracted oil was observed in 10% CO{sub 2} enriched air. Initial pH of the medium at or near 10 pH is favorable to cell growth probably by stimulating the CO{sub 2} solubilization in the medium. This is also indicated in Botryococcus braunii growth and oil formation in NaHCO{sub 3} added medium. The lack of growth in Na{sub 2}CO{sub 3} containing media was probably due to high pH. The CaCO{submore » 3} precipitation from the CA{sup ++} gelled alginate beads indicate the need for alternative immobilization systems. But the attachment of the Botryococcus braunii cells to the bottom inner surfaces of the photobioreactors may eliminate the need for gel entrapment systems as the immobilization matrices. Attachment of the Botryococcus braunii cells to the bottom inner surfaces of the photobioreactors, rather than remaining in the suspension, reduces the significance of self shadowing and related liquid height (thickness) effect. The capability of Botryococcus braunii to grow in NaHCO{sub 3} solutions is very encouraging toward development of an alkaline scrubbing system for the flue gas followed by removal of the CO{sub 2} from the alkaline solution. In such a system the pH 10 is the currently observed upper limit.« less

Cyanide is one of the main contaminants present in soil from manufactured gas plants (MGP) . Several treatment methods including thermal treatment, chemical treatment, ultraviolet irradiation, and biological treatment were evaluated for their ability to degrade the cyanide present in these soils. In the thermal treatment, raising the temperature of the purified waste to 2000--3000C resulted in complete removal of complex cyanide from the soil; however, the cyanide emitted was in a the toxic gaseous HCN form. Chemical treatment, using the oxidant Fenton`s reagent in a 10% soil slurry, resulted in the destruction of 80% of the free cyanide butmore » little, if any, complex cyanide. Ultraviolet irradiation of the basic leachate from MGP wastes in the presence of the chelating agent EDTA yielded 90% degradation of the complex cyanide. For biological treatment, using an aerobic mixed culture, almost 60% of the free cyanide disappeared from the system with minimal degradation of the complex cyanide. Each treatment has its limitations. Thus, a combined physical-chemical-biological treatment in which the complex cyanide is degraded to free cyanide by photodegradation under alkaline conditions, the free cyanide then chemically (by Fenton`s reagent) or biologically converted to NH{sub 3} and CO{sub 2}, is proposed for the removal of cyanide from MGP sites.« less

To improve octane performance and reduce emissions, MTBE and to lesser degree ETBE and TAME are blended into gasolines. These oxygenates coelute with hydrocarbon components of gasoline in GC analysis. It is known that oxonium ions are formed in the electron impact mass spectrometry of aliphatic alcohols and ethers. The base ions of t-BuOH, MTBE, ETBE, TAME, and BEE are either m/z 59 or 73 ions, and fragment ions of alkanes, alkenes, and naphthenes are at m/z 41, 43, 55, 57, 69, 71, 83, and 88. The maximum background m/z 59 and 73 ion abundances of three diluted (1:20) gasolinesmore » which are used to determine percent oxygenates in gasoline were less than 0.04% that of the lowest analyte standard used to determine the linear regression coefficients of these ethers. The background m/z 59 and 73 traces of undiluted gasoline were also studied. An ACN/gasoline partitioning cleanup technique was used to remove hydrocarbon interferences of less than 2% (v/v) oxygenated gasoline prior to identification by GC/MS. 14 refs., 4 figs., 1 tab.« less

The objective of this project was to develop a microbial culture capable of removing organic sulfur from coal. This objective was successfully achieved; thus (1) bacterial culture, capable of specifically metabolizing sulfur atoms present in organic molecules was developed and (2) using this culture, up to 91% removal of organic sulfur from coal was observed in a bioreactor. 25 refs., 30 figs., 13 tabs.

We examined the electric and thermoelectric transport properties of a superconducting Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} single crystal. The magnetic fields lower than 4 T were applied perpendicular to the electrical or thermal gradient along the {ital c} axis. All properties are described in terms of temperature-integrated excess quantities as a function of the magnetic field. Power-law exponents are compared to those found on other two-dimensional (2D) and 3D polycrystalline or textured systems. The apparent dimensionality of the system is emphasized. The values of various derived quantities are also given and compared to those of other high-temperature superconductors. These quantitiesmore » are the vortex transport entropy (ca. 10{sup {minus}15} J/K m), the viscous damping coefficient (1.2{times}10{sup {minus}9} J s/m{sup 3} at 78 K), the Ginzburg-Landau parameter (between 70 and 120), the thermal Hall angle, and the activation energies for each transport property. The findings point out the need of including the system dimensionality and various vortex pinning and vortex scattering effects in theoretical calculations.« less