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Sample records for highly selective conversion

  1. High efficiency in mode-selective frequency conversion.

    PubMed

    Quesada, Nicolás; Sipe, J E

    2016-01-15

    Frequency conversion (FC) is an enabling process in many quantum information protocols. Recently, it has been observed that upconversion efficiencies in single-photon, mode-selective FC are limited to around 80%. In this Letter, we argue that these limits can be understood as time-ordering corrections (TOCs) that modify the joint conversion amplitude of the process. Furthermore, using a simple scaling argument, we show that recently proposed cascaded FC protocols that overcome the aforementioned limitations act as "attenuators" of the TOCs. This observation allows us to argue that very similar cascaded architectures can be used to attenuate TOCs in photon generation via spontaneous parametric downconversion. Finally, by using the Magnus expansion, we argue that the TOCs, which are usually considered detrimental for FC efficiency, can also be used to increase the efficiency of conversion in partially mode-selective FC.

  2. Highly selective defect-mediated photochemical CO2 conversion over fluorite ceria under ambient conditions.

    PubMed

    Jiang, Dong; Wang, Wenzhong; Gao, Erping; Sun, Songmei; Zhang, Ling

    2014-02-25

    A highly selective defect-mediated photochemical CO2 conversion to CO over defective CeO2 nanorods under ambient conditions (CO2 400 ppm) is presented. The local strain and surface oxygen vacancies embedded in the defect-rich CeO2 are suggested to play a decisive role in mediating the photochemical CO2 conversion.

  3. High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1992-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

  4. High efficiency in Mode Selective Frequency Conversion for Optical Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Quesada, Nicolas; Sipe, J. E.

    Mode selective Frequency conversion (FC) is an enabling process in many quantum information protocols. Recently, it has been observed that upconversion efficiencies in single-photon, mode-selective FC are limited to around 80%. In this contribution we show that these limits can be understood as time ordering corrections (TOCs) that modify the joint conversion amplitude of the process. Furthermore we show, using a simple scaling argument, that recently proposed cascaded FC protocols that overcome the aforementioned limitations act as ``attenuators'' of the TOCs. This observation allows us to argue that very similar cascaded architectures can be used to attenuate TOCs in photon generation via spontaneous parametric down-conversion. Finally, by using the Magnus expansion, we argue that the TOCs, which are usually considered detrimental for FC efficiency, can also be used to increase the efficiency of conversion in partially mode selective FC.

  5. Selective catalytic conversion of bio-oil over high-silica zeolites.

    PubMed

    Widayatno, Wahyu Bambang; Guan, Guoqing; Rizkiana, Jenny; Du, Xiao; Hao, Xiaogang; Zhang, Zhonglin; Abudula, Abuliti

    2015-03-01

    Four high silica zeolites, i.e., HSZ-385, 890, 960, and 990 were utilized for the selective catalytic conversion of bio-oil from Fallopia japonica to certain chemicals in a fixed-bed reactor. The Beta-type HSZ-960 zeolite showed the highest selectivity to hydrocarbons, especially to aromatics as well as PAH compounds with the lowest unwanted chemicals while HSZ-890 showed high selectivity to aromatics. NH3-Temperature Programmed Desorption (TPD) analysis indicated that different amounts of acid sites in different zeolites determined the catalytic activity for the oxygen removal from bio-oil, in which the acid sites at low temperature (LT) region gave more contribution within the utilized temperature region. The reusability test of HSZ-960 showed the stability of hydrocarbons yield at higher temperature due to the significant contribution of coke gasification which assisted further deoxygenation of bio-oil. These results provide a guidance to select suitable zeolite catalysts for the upgrading of bio-oil in a practical process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Ultrathin and Ion-Selective Janus Membranes for High-Performance Osmotic Energy Conversion.

    PubMed

    Zhang, Zhen; Sui, Xin; Li, Pei; Xie, Ganhua; Kong, Xiang-Yu; Xiao, Kai; Gao, Longcheng; Wen, Liping; Jiang, Lei

    2017-07-05

    The osmotic energy existing in fluids is recognized as a promising "blue" energy source that can help solve the global issues of energy shortage and environmental pollution. Recently, nanofluidic channels have shown great potential for capturing this worldwide energy because of their novel transport properties contributed by nanoconfinement. However, with respect to membrane-scale porous systems, high resistance and undesirable ion selectivity remain bottlenecks, impeding their applications. The development of thinner, low-resistance membranes, meanwhile promoting their ion selectivity, is a necessity. Here, we engineered ultrathin and ion-selective Janus membranes prepared via the phase separation of two block copolymers, which enable osmotic energy conversion with power densities of approximately 2.04 W/m(2) by mixing natural seawater and river water. Both experiments and continuum simulation help us to understand the mechanism for how membrane thickness and channel structure dominate the ion transport process and overall device performance, which can serve as a general guiding principle for the future design of nanochannel membranes for high-energy concentration cells.

  7. Highly selective methodology for the direct conversion of aromatic aldehydes to glycol monoesters.

    PubMed

    Sharghi, Hashem; Sarvari, Mona Hosseini

    2003-05-16

    Al(2)O(3)/MeSO(3)H (AMA) was found to be an extremely efficient reagent for the conversion of aromatic aldehydes and diols to glycol monoesters. The remarkable selectivity achieved with this reagent is an attractive feature of the present method.

  8. Selecting a Retrospective Conversion Vendor.

    ERIC Educational Resources Information Center

    Lisowski, Andrew; Sessions, Judith

    1984-01-01

    Discussion of using vendors for retrospective conversion of library catalogs rather than in-house projects highlights reasons to consider vendors, four conversion methodologies, and vendor selection criteria (database, non-matches, local data, accuracy, charging, schedule, product delivery time, local system compatibility, MARC format, impact on…

  9. Selecting a Retrospective Conversion Vendor.

    ERIC Educational Resources Information Center

    Lisowski, Andrew; Sessions, Judith

    1984-01-01

    Discussion of using vendors for retrospective conversion of library catalogs rather than in-house projects highlights reasons to consider vendors, four conversion methodologies, and vendor selection criteria (database, non-matches, local data, accuracy, charging, schedule, product delivery time, local system compatibility, MARC format, impact on…

  10. Isolation of Cu Atoms in Pd Lattice: Forming Highly Selective Sites for Photocatalytic Conversion of CO2 to CH4.

    PubMed

    Long, Ran; Li, Yu; Liu, Yan; Chen, Shuangming; Zheng, Xusheng; Gao, Chao; He, Chaohua; Chen, Nanshan; Qi, Zeming; Song, Li; Jiang, Jun; Zhu, Junfa; Xiong, Yujie

    2017-03-29

    Photocatalytic conversion of CO2 to CH4, a carbon-neutral fuel, represents an appealing approach to remedy the current energy and environmental crisis; however, it suffers from the large production of CO and H2 by side reactions. The design of catalytic sites for CO2 adsorption and activation holds the key to address this grand challenge. In this Article, we develop highly selective sites for photocatalytic conversion of CO2 to CH4 by isolating Cu atoms in Pd lattice. According to our synchrotron-radiation characterizations and theoretical simulations, the isolation of Cu atoms in Pd lattice can play dual roles in the enhancement of CO2-to-CH4 conversion: (1) providing the paired Cu-Pd sites for the enhanced CO2 adsorption and the suppressed H2 evolution; and (2) elevating the d-band center of Cu sites for the improved CO2 activation. As a result, the Pd7Cu1-TiO2 photocatalyst achieves the high selectivity of 96% for CH4 production with a rate of 19.6 μmol gcat(-1) h(-1). This work provides fresh insights into the catalytic site design for selective photocatalytic CO2 conversion, and highlights the importance of catalyst lattice engineering at atomic precision to catalytic performance.

  11. The Highly Selective and Near-Quantitative Conversion of Glucose to 5-Hydroxymethylfurfural Using Ionic Liquids

    PubMed Central

    Eminov, Sanan; Brandt, Agnieszka; Wilton-Ely, James D. E. T.

    2016-01-01

    A number of ionic liquids have been shown to be excellent solvents for lignocellulosic biomass processing, and some of these are particularly effective in the production of the versatile chemical building block 5-hydroxymethylfurfural (HMF). In this study, the production of HMF from the simple sugar glucose in ionic liquid media is discussed. Several aspects of the selective catalytic formation of HMF from glucose have been elucidated using metal halide salts in two distinct ionic liquids, 1-butyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium hydrogen sulfate as well as mixtures of these, revealing key features for accelerating the desired reaction and suppressing byproduct formation. The choice of ionic liquid anion is revealed to be of particular importance, with low HMF yields in the case of hydrogen sulfate-based salts, which are reported to be effective for HMF production from fructose. The most successful system investigated in this study led to almost quantitative conversion of glucose to HMF (90% in only 30 minutes using 7 mol% catalyst loading at 120°C) in a system which is selective for the desired product, has low energy intensity and is environmentally benign. PMID:27711238

  12. High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

    1993-01-01

    Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.

  13. Direct conversion of CO2 into liquid fuels with high selectivity over a bifunctional catalyst

    NASA Astrophysics Data System (ADS)

    Gao, Peng; Li, Shenggang; Bu, Xianni; Dang, Shanshan; Liu, Ziyu; Wang, Hui; Zhong, Liangshu; Qiu, Minghuang; Yang, Chengguang; Cai, Jun; Wei, Wei; Sun, Yuhan

    2017-10-01

    Although considerable progress has been made in carbon dioxide (CO2) hydrogenation to various C1 chemicals, it is still a great challenge to synthesize value-added products with two or more carbons, such as gasoline, directly from CO2 because of the extreme inertness of CO2 and a high C-C coupling barrier. Here we present a bifunctional catalyst composed of reducible indium oxides (In2O3) and zeolites that yields a high selectivity to gasoline-range hydrocarbons (78.6%) with a very low methane selectivity (1%). The oxygen vacancies on the In2O3 surfaces activate CO2 and hydrogen to form methanol, and C‑C coupling subsequently occurs inside zeolite pores to produce gasoline-range hydrocarbons with a high octane number. The proximity of these two components plays a crucial role in suppressing the undesired reverse water gas shift reaction and giving a high selectivity for gasoline-range hydrocarbons. Moreover, the pellet catalyst exhibits a much better performance during an industry-relevant test, which suggests promising prospects for industrial applications.

  14. Porous MOF with Highly Efficient Selectivity and Chemical Conversion for CO2.

    PubMed

    Wang, Hai-Hua; Hou, Lei; Li, Yong-Zhi; Jiang, Chen-Yu; Wang, Yao-Yu; Zhu, Zhonghua

    2017-05-31

    A new Co(II)-based MOF, {[Co2(tzpa)(OH)(H2O)2]·DMF}n (1) (H3tzpa = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid), was constructed by employing a tetrazolyl-carboxyl ligand H3tzpa. 1 possesses 1D tubular channels that are decorated by μ3-OH groups, uncoordinated carboxylate O atoms, and open metal centers generated by the removal of coordinated water molecules, leading to high CO2 adsorption capacity and significantly selective capture for CO2 over CH4 and CO in the temperature range of 298-333 K. Moreover, 1 shows the chemical stability in acidic and basic aqueous solutions. Grand canonical Monte Carlo simulations identified multiple CO2-philic sites in 1. In addition, the activated 1 as the heterogeneous Lewis and Brønsted acid bifunctional catalyst facilitates the chemical fixation of CO2 coupling with epoxides into cyclic carbonates under ambient conditions.

  15. Potassium-Promoted Molybdenum Carbide as a Highly Active and Selective Catalyst for CO2 Conversion to CO.

    PubMed

    Porosoff, Marc D; Baldwin, Jeffrey W; Peng, Xi; Mpourmpakis, Giannis; Willauer, Heather D

    2017-06-09

    The high concentration of CO2 bound in seawater represents a significant opportunity to extract and use this CO2 as a C1 feedstock for synthetic fuels. Using an existing process, CO2 and H2 can be concurrently extracted from seawater and then catalytically reacted to produce synthetic fuel. Hydrogenating CO2 directly into liquid hydrocarbons is exceptionally difficult, but by first identifying a catalyst for selective CO production through the reverse water-gas shift (RWGS) reaction, CO can then be hydrogenated to fuel through Fischer-Tropsch (FT) synthesis. Results of this study demonstrate that potassium-promoted molybdenum carbide supported on γ-Al2 O3 (K-Mo2 C/γ-Al2 O3 ) is a low-cost, stable, and highly selective catalyst for RWGS over a wide range of conversions. These findings are supported by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Conversion of biomass to selected chemical products.

    PubMed

    Gallezot, Pierre

    2012-02-21

    This critical review provides a survey illustrated by recent references of different strategies to achieve a sustainable conversion of biomass to bioproducts. Because of the huge number of chemical products that can be potentially manufactured, a selection of starting materials and targeted chemicals has been done. Also, thermochemical conversion processes such as biomass pyrolysis or gasification as well as the synthesis of biofuels were not considered. The synthesis of chemicals by conversion of platform molecules obtained by depolymerisation and fermentation of biopolymers is presently the most widely envisioned approach. Successful catalytic conversion of these building blocks into intermediates, specialties and fine chemicals will be examined. However, the platform molecule value chain is in competition with well-optimised, cost-effective synthesis routes from fossil resources to produce chemicals that have already a market. The literature covering alternative value chains whereby biopolymers are converted in one or few steps to functional materials will be analysed. This approach which does not require the use of isolated, pure chemicals is well adapted to produce high tonnage products, such as paper additives, paints, resins, foams, surfactants, lubricants, and plasticisers. Another objective of the review was to examine critically the green character of conversion processes because using renewables as raw materials does not exempt from abiding by green chemistry principles (368 references).

  17. Selective conversion of syngas to light olefins.

    PubMed

    Jiao, Feng; Li, Jinjing; Pan, Xiulian; Xiao, Jianping; Li, Haobo; Ma, Hao; Wei, Mingming; Pan, Yang; Zhou, Zhongyue; Li, Mingrun; Miao, Shu; Li, Jian; Zhu, Yifeng; Xiao, Dong; He, Ting; Yang, Junhao; Qi, Fei; Fu, Qiang; Bao, Xinhe

    2016-03-04

    Although considerable progress has been made in direct synthesis gas (syngas) conversion to light olefins (C2(=)-C4(=)) via Fischer-Tropsch synthesis (FTS), the wide product distribution remains a challenge, with a theoretical limit of only 58% for C2-C4 hydrocarbons. We present a process that reaches C2(=)-C4(=) selectivity as high as 80% and C2-C4 94% at carbon monoxide (CO) conversion of 17%. This is enabled by a bifunctional catalyst affording two types of active sites with complementary properties. The partially reduced oxide surface (ZnCrO(x)) activates CO and H2, and C-C coupling is subsequently manipulated within the confined acidic pores of zeolites. No obvious deactivation is observed within 110 hours. Furthermore, this composite catalyst and the process may allow use of coal- and biomass-derived syngas with a low H2/CO ratio.

  18. Pd@Cu(II)-MOF-Catalyzed Aerobic Oxidation of Benzylic Alcohols in Air with High Conversion and Selectivity.

    PubMed

    Chen, Gong-Jun; Wang, Jing-Si; Jin, Fa-Zheng; Liu, Ming-Yang; Zhao, Chao-Wei; Li, Yan-An; Dong, Yu-Bin

    2016-03-21

    A new 3D porous Cu(II)-MOF (1) was synthesized based on a ditopic pyridyl substituted diketonate ligand and Cu(OAc)2 in solution, and it features a 3D NbO motif which is determined by the X-ray crystallography. Furthermore, the Pd NPs-loaded hybrid material Pd@Cu(II)-MOF (2) was prepared based on 1 via solution impregnation, and its structure was confirmed by HRTEM, SEM, XRPD, gas adsorption-desorption, and ICP measurement. 2 exhibits excellent catalytic activity (conversion, 93% to >99%) and selectivity (>99% to benzaldehydes) for various benzyl alcohol substrates (benzyl alcohol and its derivatives with electron-withdrawing and electron-donating groups) oxidation reactions in air. In addition, 2 is a typical heterogeneous catalyst, which was confirmed by hot solution leaching experiment, and it can be recycled at least six times without significant loss of its catalytic activity and selectivity.

  19. High selective conversion of methane to carbon monoxide and the effects of chlorine additives in the gas and solid phases on the oxidation of methane on strontium hydroxyapatites

    SciTech Connect

    Sugiyama, Shigeru; Minami, Toshimitsu; Higaki, Tomonori; Hayashi, Hiromu; Moffat, J.B.

    1997-02-01

    Selectivities to carbon monoxide higher than 90% for conversions of methane greater than 10% were obtained from the partial oxidation of methane on stoichiometric strontium hydroxyapatite (SrHAp1.67) at 873 K during 6 h on stream. However, the activities decreased gradually with increasing the time-on-stream to 78 h due to the transformation of the apatite to Sr{sub 3}(PO{sub 4}){sub 2}. With small quantities of tetrachloromethane (TCM) added to the feedstream, the high selectivity to CO was retained while the conversion suffered a marked decrease with increasing the times-on-stream. In the presence of TCM the catalytic solid consists of a complex mixture of hydroxyapatite, chlorapatite, phosphate and chloride, each of which contributes dissimilarly to the catalytic process.

  20. High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode

    DOE PAGES

    Song, Yang; Peng, Rui; Hensley, Dale K.; ...

    2016-09-28

    Carbon dioxide is a pollutant, but also a potential carbon source provided an efficient means to convert it to useful products. Herein we report a nanostructured catalyst for the direct electrochemical reduction of dissolved CO2 to ethanol with high Faradaic efficiency (63%) and high selectivity (84%). The catalyst is comprised of Cu nanoparticle on a highly textured, N-doped graphene film. Detailed electrochemical analysis and complementary DFT calculations indicate a novel mechanism in which multiple active sites, working sequentially, control the coupling of carbon monoxide radicals and mediate the subsequent electrochemical reduction to alcohol.

  1. Selective Conversion of Biorefinery Lignin into Dicarboxylic Acids

    SciTech Connect

    Ma, Ruoshui; Guo, Mond; Zhang, Xiao

    2014-02-01

    The emerging biomass-to-biofuel conversion industry has created an urgent need for identifying new applications for biorefinery lignin. This paper demonstrates a new route to producing dicarboxylic acids from biorefinery lignin through chalcopyrite-catalyzed oxidation in a highly selective process. Up to 95 % selectivity towards stable dicarboxylic acids was obtained for several types of biorefinery lignin and model compounds under mild, environmentally friendly reaction conditions. The findings from this study paved a new avenue to biorefinery lignin conversions and applications.

  2. A Nitrogen-Doped Carbon Catalyst for Electrochemical CO2 Conversion to CO with High Selectivity and Current Density.

    PubMed

    Jhong, Huei-Ru Molly; Tornow, Claire E; Smid, Bretislav; Gewirth, Andrew A; Lyth, Stephen M; Kenis, Paul J A

    2017-03-22

    We report characterization of a non-precious metal-free catalyst for the electrochemical reduction of CO2 to CO; namely, a pyrolyzed carbon nitride and multiwall carbon nanotube composite. This catalyst exhibits a high selectivity for production of CO over H2 (approximately 98 % CO and 2 % H2 ), as well as high activity in an electrochemical flow cell. The CO partial current density at intermediate cathode potentials (V=-1.46 V vs. Ag/AgCl) is up to 3.5× higher than state-of-the-art Ag nanoparticle-based catalysts, and the maximum current density is 90 mA cm(-2) . The mass activity and energy efficiency (up to 48 %) were also higher than the Ag nanoparticle reference. Moving away from precious metal catalysts without sacrificing activity or selectivity may significantly enhance the prospects of electrochemical CO2 reduction as an approach to reduce atmospheric CO2 emissions or as a method for load-leveling in relation to the use of intermittent renewable energy sources.

  3. Aqueous and Template-Free Synthesis of Meso-Macroporous Polymers for Highly Selective Capture and Conversion of CO2.

    PubMed

    Huang, Kuan; Liu, Fujian; Jiang, Lilong; Dai, Sheng

    2017-09-01

    Meso-macroporous polymers possessing nitrogen functionality were innovatively synthesized via an aqueous and template-free route in this work. Specifically, the polymerization of 1-(4-vinylbenzyl)-1,3,5,7-tetraazaadamantan-1-ium chloride in aqueous solutions under high temperatures induces the decomposition of hexamethylenetetramine unit into ammonia and formaldehyde molecules, followed by the cross-linking of benzene rings via "resol chemistry". During this process, extended meso-macroporous frameworks were constructed, and meanwhile active nitrogen species were incoporated. Taking the advantage of meso-macroporosity and nitrogen functionality, the synthesized polymers offer competitive CO2 capacities (0.37-1.58 mmol/g at 0˚C and 0.15 bar) and extraodinary CO2/N2 selectivities (155-324 at 0 ˚C). Furthermore, after complexed with metal ions, the synthesized polymers show excellent activity for catalyzing the cycloaddition of propylene oxide with CO2 (Yield>98.5%, TOF: 612.9-761.1 h-1). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Materials for high-temperature thermoelectric conversion

    NASA Technical Reports Server (NTRS)

    Feigelson, R. S.; Elwell, D.; Auld, B. A.

    1984-01-01

    The development of materials for high temperature thermoelectric energy conversion devices was investigated. The development of new criteria for the selection of materials which is based on understanding of the fundamental principles governing the behavior of high temperature thermoelectric materials is discussed. The synthesis and characterization of promising new materials and the growth of single crystals to eliminate possible problems associated with grain boundaries and other defects in polycrystalline materials are outlined.

  5. Selective conversion of biorefinery lignin into dicarboxylic acids.

    PubMed

    Ma, Ruoshui; Guo, Mond; Zhang, Xiao

    2014-02-01

    The emerging biomass-to-biofuel conversion industry has created an urgent need for identifying new applications for biorefinery lignin. This paper demonstrates a new route to producing dicarboxylic acids from biorefinery lignin through chalcopyrite-catalyzed oxidation in a highly selective process. Up to 95 % selectivity towards stable dicarboxylic acids was obtained for several types of biorefinery lignin and model compounds under mild, environmentally friendly reaction conditions. The findings from this study paved a new avenue to biorefinery lignin conversions and applications. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Dziendziel, Randolph J.; DePoy, David Moore; Baldasaro, Paul Francis

    2007-01-23

    This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

  7. Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system

    DOEpatents

    Dziendziel, Randolph J.; Baldasaro, Paul F.; DePoy, David M.

    2010-09-07

    This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

  8. Mesophilic and Thermophilic Conditions Select for Unique but Highly Parallel Microbial Communities to Perform Carboxylate Platform Biomass Conversion

    PubMed Central

    Hollister, Emily B.; Forrest, Andrea K.; Wilkinson, Heather H.; Ebbole, Daniel J.; Tringe, Susannah G.; Malfatti, Stephanie A.; Holtzapple, Mark T.; Gentry, Terry J.

    2012-01-01

    The carboxylate platform is a flexible, cost-effective means of converting lignocellulosic materials into chemicals and liquid fuels. Although the platform's chemistry and engineering are well studied, relatively little is known about the mixed microbial communities underlying its conversion processes. In this study, we examined the metagenomes of two actively fermenting platform communities incubated under contrasting temperature conditions (mesophilic 40°C; thermophilic 55°C), but utilizing the same inoculum and lignocellulosic feedstock. Community composition segregated by temperature. The thermophilic community harbored genes affiliated with Clostridia, Bacilli, and a Thermoanaerobacterium sp, whereas the mesophilic community metagenome was composed of genes affiliated with other Clostridia and Bacilli, Bacteriodia, γ-Proteobacteria, and Actinobacteria. Although both communities were able to metabolize cellulosic materials and shared many core functions, significant differences were detected with respect to the abundances of multiple Pfams, COGs, and enzyme families. The mesophilic metagenome was enriched in genes related to the degradation of arabinose and other hemicellulose-derived oligosaccharides, and the production of valerate and caproate. In contrast, the thermophilic community was enriched in genes related to the uptake of cellobiose and the transfer of genetic material. Functions assigned to taxonomic bins indicated that multiple community members at either temperature had the potential to degrade cellulose, cellobiose, or xylose and produce acetate, ethanol, and propionate. The results of this study suggest that both metabolic flexibility and functional redundancy contribute to the platform's ability to process lignocellulosic substrates and are likely to provide a degree of stability to the platform's fermentation processes. PMID:22761870

  9. Thermophotovoltaic energy conversion using photonic bandgap selective emitters

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2003-06-24

    A method for thermophotovoltaic generation of electricity comprises heating a metallic photonic crystal to provide selective emission of radiation that is matched to the peak spectral response of a photovoltaic cell that converts the radiation to electricity. The use of a refractory metal, such as tungsten, for the photonic crystal enables high temperature operation for high radiant flux and high dielectric contrast for a full 3D photonic bandgap, preferable for efficient thermophotovoltaic energy conversion.

  10. Conversion of a putative Agrobacterium sugar-binding protein into a FRET sensor with high selectivity for sucrose.

    PubMed

    Lager, Ida; Looger, Loren L; Hilpert, Melanie; Lalonde, Sylvie; Frommer, Wolf B

    2006-10-13

    Glucose is the main sugar transport form in animals, whereas plants use sucrose to supply non-photosynthetic organs with carbon skeletons and energy. Many aspects of sucrose transport, metabolism, and signaling are not well understood, including the route of sucrose efflux from leaf mesophyll cells and transport across vacuolar membranes. Tools that can detect sucrose with high spatial and temporal resolution in intact organs may help elucidate the players involved. Here, FRET sensors were generated by fusing putative sucrose-binding proteins to green fluorescent protein variants. Plant-associated bacteria such as Rhizobium and Agrobacterium can use sucrose as a nutrient source; sugar-binding proteins were, thus, used as scaffolds for developing sucrose nanosensors. Among a set of putative sucrose-binding protein genes cloned in between eCFP and eYFP and tested for sugar-dependent FRET changes, an Agrobacterium sugar-binding protein bound sucrose with 4 mum affinity. This FLIPsuc-4mu protein also recognized other sugars including maltose, trehalose, and turanose and, with lower efficiency, glucose and palatinose. Homology modeling enabled the prediction of binding pocket mutations to modulate the relative affinity of FLIPsuc-4mu for sucrose, maltose, and glucose. Mutant nanosensors showed up to 50- and 11-fold increases in specificity for sucrose over maltose and glucose, respectively, and the sucrose binding affinity was simultaneously decreased to allow detection in the physiological range. In addition, the signal-to-noise ratio of the sucrose nanosensor was improved by linker engineering. This novel reagent complements FLIPs for glucose, maltose, ribose, glutamate, and phosphate and will be used for analysis of sucrose-derived carbon flux in bacterial, fungal, plant, and animal cells.

  11. Automatic source speaker selection for voice conversion.

    PubMed

    Turk, Oytun; Arslan, Levent M

    2009-01-01

    This paper focuses on the importance of source speaker selection for a weighted codebook mapping based voice conversion algorithm. First, the dependency on source speakers is evaluated in a subjective listening test using 180 different source-target pairs from a database of 20 speakers. Subjective scores for similarity to target speaker's voice and quality are obtained. Statistical analysis of scores confirms the dependence of performance on source speakers for both male-to-male and female-to-female transformations. A source speaker selection algorithm is devised given a target speaker and a set of source speaker candidates. For this purpose, an artificial neural network (ANN) is trained that learns the regression between a set of acoustical distance measures and the subjective scores. The estimated scores are used in source speaker ranking. The average cross-correlation coefficient between rankings obtained from median subjective scores and rankings estimated by the algorithm is 0.84 for similarity and 0.78 for quality in male-to-male transformations. The results for female-to-female transformations were less reliable with a cross-correlation value of 0.58 for both similarity and quality.

  12. Highly efficient (infra)red conversion of InGaN light emitting diodes by nanocrystals, enhanced by colour selective mirrors.

    PubMed

    Roither, Jürgen; Kovalenko, Maksym V; Heiss, Wolfgang

    2008-09-03

    Colloidal nanocrystal layers deposited onto the enclosure of InGaN light emitting diodes are demonstrated to operate as nano-phosphors for colour conversion with high colour stability. Depending on the choice of the nanocrystal material (either CdSe/ZnS or PbS nanocrystals are applied), the diode emission at 470 nm is converted to red or to infrared light, with similar quantum efficiencies. The colour conversion is further improved by dielectric mirrors with high reflectivity at the emission band of the nanocrystals, resulting in an almost doubling of the nanocrystal light extraction from the devices, which increases the nanocrystal device efficiency up to 19.1%.

  13. Selective solvent absorption in coal conversion

    SciTech Connect

    Larsen, J.W.; Amui, J.

    1992-06-01

    The objectives of this research are: (1) to determine the importance of the presence of added hydrogen donor compounds within the coal in the first stage of direct liquefaction processes; and (2) to determine the composition of the solvent absorbed by and present within the coal in the first stages of direct coal liquefaction. Scope of work study the conversion of Argonne Premium coals in tetralin and 2-t-butyltetralin and compare the following: conversion to soluble products and product composition. Hydrogen donated by both solvents will be measured by gas chromatography and the same technique will be used to establish the amount of dealkylation of 2-t-butyltetralin. Reactions will be performed at several different temperatures for varying amounts of time.

  14. Using Ionic Liquids in Selective Hydrocarbon Conversion Processes

    SciTech Connect

    Tang, Yongchun; Periana, Roy; Chen, Weiqun; van Duin, Adri; Nielsen, Robert; Shuler, Patrick; Ma, Qisheng; Blanco, Mario; Li, Zaiwei; Oxgaard, Jonas; Cheng, Jihong; Cheung, Sam; Pudar, Sanja

    2009-09-28

    This is the Final Report of the five-year project Using Ionic Liquids in Selective Hydrocarbon Conversion Processes (DE-FC36-04GO14276, July 1, 2004- June 30, 2009), in which we present our major accomplishments with detailed descriptions of our experimental and theoretical efforts. Upon the successful conduction of this project, we have followed our proposed breakdown work structure completing most of the technical tasks. Finally, we have developed and demonstrated several optimized homogenously catalytic methane conversion systems involving applications of novel ionic liquids, which present much more superior performance than the Catalytica system (the best-to-date system) in terms of three times higher reaction rates and longer catalysts lifetime and much stronger resistance to water deactivation. We have developed in-depth mechanistic understandings on the complicated chemistry involved in homogenously catalytic methane oxidation as well as developed the unique yet effective experimental protocols (reactors, analytical tools and screening methodologies) for achieving a highly efficient yet economically feasible and environmentally friendly catalytic methane conversion system. The most important findings have been published, patented as well as reported to DOE in this Final Report and our 20 Quarterly Reports.

  15. High-Temperature Thermoelectric Energy Conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.

    1987-01-01

    Theory of thermoelectric energy conversion at high temperatures and status of research on conversion materials reviewed in report. Shows highest values of thermoelectric figure of merit, Z, found in semiconductor materials. Semiconductors keep wide choice of elements and compounds. Electrical properties tailored to particular application by impurity doping and control of stoichiometry. Report develops definition of Z useful for comparing materials and uses it to evaluate potentials of different classes of materialsmetals, semiconductors, and insulators.

  16. High-Temperature Thermoelectric Energy Conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.

    1987-01-01

    Theory of thermoelectric energy conversion at high temperatures and status of research on conversion materials reviewed in report. Shows highest values of thermoelectric figure of merit, Z, found in semiconductor materials. Semiconductors keep wide choice of elements and compounds. Electrical properties tailored to particular application by impurity doping and control of stoichiometry. Report develops definition of Z useful for comparing materials and uses it to evaluate potentials of different classes of materialsmetals, semiconductors, and insulators.

  17. High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode

    SciTech Connect

    Song, Yang; Peng, Rui; Hensley, Dale K.; Bonnesen, Peter V.; Liang, Liangbo; Wu, Zili; Meyer, Harry M.; Chi, Miaofang; Ma, Cheng; Sumpter, Bobby G.; Rondinone, Adam J.

    2016-09-28

    Carbon dioxide is a pollutant, but also a potential carbon source provided an efficient means to convert it to useful products. Herein we report a nanostructured catalyst for the direct electrochemical reduction of dissolved CO2 to ethanol with high Faradaic efficiency (63%) and high selectivity (84%). The catalyst is comprised of Cu nanoparticle on a highly textured, N-doped graphene film. Detailed electrochemical analysis and complementary DFT calculations indicate a novel mechanism in which multiple active sites, working sequentially, control the coupling of carbon monoxide radicals and mediate the subsequent electrochemical reduction to alcohol.

  18. Garden Banks 388 floating production vessel selection and conversion

    SciTech Connect

    Taylor, M.J.; McBee, H.E.; Edelblum, L.S.; Henderson, A.D.; Scovell, D.C.

    1995-12-31

    This paper presents the key elements involved in the selection of the Ocean Victory Class semisubmersible drilling vessel by Enserch Exploration, Inc. for conversion to a Floating Production Facility (FPF). It also presents an overview of the various facets of engineering required to specify and procure all mooring, production facilities and marine systems equipment, and all structural and naval architectural design work necessary to obtain ABS classification and provide a conversion specification bid package and detailed design.

  19. Integrated process for high conversion and high yield protein PEGylation.

    PubMed

    Pfister, David; Morbidelli, Massimo

    2016-08-01

    Over the past decades, PEGylation has become a powerful technique to increase the in vivo circulation half-life of therapeutic proteins while maintaining their activity. The development of new therapeutic proteins is likely to require further improvement of the PEGylation methods to reach even better selectivity and yield for reduced costs. The intensification of the PEGylation process was investigated through the integration of a chromatographic step in order to increase yield and conversion for the production of mono-PEGylated protein. Lysozyme was used as a model protein to demonstrate the feasibility of such approach. In the integrated reaction/separation process, chromatography was used as fractionation technique in order to isolate and recycle the unreacted protein from the PEGylated products. This allows operating the reactor with short reaction times so as to minimize the production of multi-PEGylated proteins (i.e., conjugated to more than one polymer). That is, the reaction is stopped before the desired product (i.e., the mono-PEGylated protein) can further react, thus leading to limited conversion but high yield. The recycling of the unreacted protein was then considered to drive the protein overall conversion to completion. This approach has great potential to improve processes whose yield is limited by the further reaction of the product leading to undesirable by-products. Biotechnol. Bioeng. 2016;113: 1711-1718. © 2016 Wiley Periodicals, Inc.

  20. Selective catalytic process for conversion of light naphtha to aromatics

    SciTech Connect

    Law, D.V.; Tamm, P.W.; Detz, C.M.

    1987-01-01

    AROMAX catalyst represents a unique advance in the development of modern reforming catalysts. The catalyst employs a zeolite to take advantage of a conversion chemistry that is entirely different from that of conventional reforming catalysts. This process chemistry, however, can still be carried out under process conditions which are essentially identical to those of conventional reforming. The result is the use of conventional designs and hardware to achieve highly efficient conversion of previously undesirable light feedstocks to high value aromatics.

  1. High partial feed conversion efficiency appears to be a persistent trait associated with reduction in selected measures of methane emissions in dairy cattle

    USDA-ARS?s Scientific Manuscript database

    In the United States enteric methane (CH4) contributes approximately 21% of all anthropogenic CH4 emissions. Alongside dietary manipulations, exploiting among-animal variation in feed conversion efficiency (FCE) may offer possible CH4 mitigation strategies. This experiment was designed to evaluate t...

  2. Highly active Au/δ-MoC and Cu/δ-MoC catalysts for the conversion of CO2: The metal/C ratio as a key factor defining activity, selectivity, and stability

    DOE PAGES

    Posada-Pérez, Sergio; Ramírez, Pedro J.; Evans, Jaime; ...

    2016-06-16

    The ever growing increase of CO2 concentration in the atmosphere is one of the main causes of global warming. Thus, CO2 activation and conversion toward valuable added compounds is a major scientific challenge. A new set of Au/δ-MoC and Cu/δ-MoC catalysts exhibits high activity, selectivity, and stability for the reduction of CO2 to CO with some subsequent selective hydrogenation toward methanol. Sophisticated experiments under controlled conditions and calculations based on density functional theory have been used to study the unique behavior of these systems. A detailed comparison of the behavior of Au/β-Mo2C and Au/δ-MoC catalysts provides evidence of the impactmore » of the metal/carbon ratio in the carbide on the performance of the catalysts. The present results show that this ratio governs the chemical behavior of the carbide and the properties of the admetal, up to the point of being able to switch the rate and mechanism of the process for CO2 conversion. Here, a control of the metal/carbon ratio paves the road for an efficient reutilization of this environmental harmful greenhouse gas.« less

  3. Highly active Au/δ-MoC and Cu/δ-MoC catalysts for the conversion of CO2: The metal/C ratio as a key factor defining activity, selectivity, and stability

    SciTech Connect

    Posada-Pérez, Sergio; Ramírez, Pedro J.; Evans, Jaime; Viñes, Francesc; Liu, Ping; Illas, Francesc; Rodriguez, José A.

    2016-06-16

    The ever growing increase of CO2 concentration in the atmosphere is one of the main causes of global warming. Thus, CO2 activation and conversion toward valuable added compounds is a major scientific challenge. A new set of Au/δ-MoC and Cu/δ-MoC catalysts exhibits high activity, selectivity, and stability for the reduction of CO2 to CO with some subsequent selective hydrogenation toward methanol. Sophisticated experiments under controlled conditions and calculations based on density functional theory have been used to study the unique behavior of these systems. A detailed comparison of the behavior of Au/β-Mo2C and Au/δ-MoC catalysts provides evidence of the impact of the metal/carbon ratio in the carbide on the performance of the catalysts. The present results show that this ratio governs the chemical behavior of the carbide and the properties of the admetal, up to the point of being able to switch the rate and mechanism of the process for CO2 conversion. Here, a control of the metal/carbon ratio paves the road for an efficient reutilization of this environmental harmful greenhouse gas.

  4. Highly active Au/δ-MoC and Cu/δ-MoC catalysts for the conversion of CO2: The metal/C ratio as a key factor defining activity, selectivity, and stability

    SciTech Connect

    Posada-Pérez, Sergio; Ramírez, Pedro J.; Evans, Jaime; Viñes, Francesc; Liu, Ping; Illas, Francesc; Rodriguez, José A.

    2016-06-16

    The ever growing increase of CO2 concentration in the atmosphere is one of the main causes of global warming. Thus, CO2 activation and conversion toward valuable added compounds is a major scientific challenge. A new set of Au/δ-MoC and Cu/δ-MoC catalysts exhibits high activity, selectivity, and stability for the reduction of CO2 to CO with some subsequent selective hydrogenation toward methanol. Sophisticated experiments under controlled conditions and calculations based on density functional theory have been used to study the unique behavior of these systems. A detailed comparison of the behavior of Au/β-Mo2C and Au/δ-MoC catalysts provides evidence of the impact of the metal/carbon ratio in the carbide on the performance of the catalysts. The present results show that this ratio governs the chemical behavior of the carbide and the properties of the admetal, up to the point of being able to switch the rate and mechanism of the process for CO2 conversion. Here, a control of the metal/carbon ratio paves the road for an efficient reutilization of this environmental harmful greenhouse gas.

  5. Thermophotovoltaic conversion using selective infrared line emitters and large band gap photovoltaic devices

    DOEpatents

    Brandhorst, Jr., Henry W.; Chen, Zheng

    2000-01-01

    Efficient thermophotovoltaic conversion can be performed using photovoltaic devices with a band gap in the 0.75-1.4 electron volt range, and selective infrared emitters chosen from among the rare earth oxides which are thermally stimulated to emit infrared radiation whose energy very largely corresponds to the aforementioned band gap. It is possible to use thermovoltaic devices operating at relatively high temperatures, up to about 300.degree. C., without seriously impairing the efficiency of energy conversion.

  6. Scalable, "Dip-and-Dry" Fabrication of a Wide-Angle Plasmonic Selective Absorber for High-Efficiency Solar-Thermal Energy Conversion.

    PubMed

    Mandal, Jyotirmoy; Wang, Derek; Overvig, Adam C; Shi, Norman N; Paley, Daniel; Zangiabadi, Amirali; Cheng, Qian; Barmak, Katayun; Yu, Nanfang; Yang, Yuan

    2017-08-28

    A galvanic-displacement-reaction-based, room-temperature "dip-and-dry" technique is demonstrated for fabricating selectively solar-absorbing plasmonic-nanoparticle-coated foils (PNFs). The technique, which allows for facile tuning of the PNFs' spectral reflectance to suit different radiative and thermal environments, yields PNFs which exhibit excellent, wide-angle solar absorptance (0.96 at 15°, to 0.97 at 35°, to 0.79 at 80°), and low hemispherical thermal emittance (0.10) without the aid of antireflection coatings. The thermal emittance is on par with those of notable selective solar absorbers (SSAs) in the literature, while the wide-angle solar absorptance surpasses those of previously reported SSAs with comparable optical selectivities. In addition, the PNFs show promising mechanical and thermal stabilities at temperatures of up to 200 °C. Along with the performance of the PNFs, the simplicity, inexpensiveness, and environmental friendliness of the "dip-and-dry" technique makes it an appealing alternative to current methods for fabricating selective solar absorbers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Let Them Talk!: Teaching High School Spanish Conversation.

    ERIC Educational Resources Information Center

    Konopacki, Steven

    1990-01-01

    Describes the use of conversational partnerships (CP) in high school Spanish classes. CPs seek to improve spoken proficiency by allowing students to rehearse conversational roles, plan strategies, and polish pronunciation. (CB)

  8. High pressure synthesis gas conversion. Final report

    SciTech Connect

    Not Available

    1993-05-01

    The purpose of this research project is to build and test a high pressure fermentation system for the production of ethanol from synthesis gas. The fermenters, pumps, controls, and analytical system were procured or fabricated and assembled in our laboratory. This system was then used to determine the effects of high pressure on growth and ethanol production by Clostridium ljungdahlii. The limits of cell concentration and mass transport relationships were found in CSTR and immobilized cell reactors (ICR). The minimum retention times and reactor volumes were found for ethanol production in these reactors. A maximum operating pressure of 150 psig has been shown to be possible for C. ljungdahlli with the medium of Phillips et al. This medium was developed for atmospheric pressure operation in the CSTR to yield maximum ethanol concentrations and thus is not best for operation at elevated pressures. It is recommended that a medium development study be performed for C. ljungdahlii at increased pressure. Cell concentration, gas conversion and product concentration profiles were presented for C. ljungdahlii as a function of gas flow rate, the variable which affects bacterium performance the most. This pressure was chosen as a representative pressure over the 0--150 psig operating pressure range for the bacterium. Increased pressure negatively affected ethanol productivity probably due to the fact that medium composition was designed for atmospheric pressure operation. Medium development at increased pressure is necessary for high pressure development of the system.

  9. Drilling fluid conversion: Selection and use of Portland or blast-furnace-slag cement

    SciTech Connect

    Schlemmer, R.P.; Branam, N.E.; Edwards, T.M.; Valenziano, R.C.

    1994-12-01

    Conversion of drilling mud to oilwell cement has advanced from an unpredictable laboratory curiosity to a practical reality. Recent field introduction of polymer dispersants, organic accelerators, and an alternative cementitious material have provided two refined and practical conversion methods. Each method claims universal applicability plus performance superior to that of conventionally mixed and pumped Portland cement. Both blast-furnace-slag (BFS) and Portland cement are used for drilling-mud conversion. Portland and BFS mud conversions can use the same recently developed polymer dispersants, filtration-control materials, defoamers, and other additives that are typically used to treat high-temperature, highly-salt-contaminated drilling muds. Experience in the field and laboratory has demonstrated that conversion with BFS or Portland cement is essentially one technology from a pilot-test and application standpoint. While use of these two materials reflects essentially one technology, distinct performance and cost differences exist. These differences define the specific economic application advantages and must be considered when a decision to use BFS or Portland cement is made. Rational selection of mud-to-cement conversion depends on a detailed economic comparison of basic materials, logistics, and equipment availability.

  10. Selecting and applying cesium-137 conversion models to estimate soil erosion rates in cultivated fields.

    PubMed

    Li, Sheng; Lobb, David A; Tiessen, Kevin H D; McConkey, Brian G

    2010-01-01

    The fallout radionuclide cesium-137 ((137)Cs) has been successfully used in soil erosion studies worldwide. However, discrepancies often exist between the erosion rates estimated using various conversion models. As a result, there is often confusion in the use of the various models and in the interpretation of the data. Therefore, the objective of this study was to test the structural and parametrical uncertainties associated with four conversion models typically used in cultivated agricultural landscapes. For the structural uncertainties, the Soil Constituent Redistribution by Erosion Model (SCREM) was developed and used to simulate the redistribution of fallout (137)Cs due to tillage and water erosion along a simple two-dimensional (horizontal and vertical) transect. The SCREM-predicted (137)Cs inventories were then imported into the conversion models to estimate the erosion rates. The structural uncertainties of the conversion models were assessed based on the comparisons between the conversion-model-estimated erosion rates and the erosion rates determined or used in the SCREM. For the parametrical uncertainties, test runs were conducted by varying the values of the parameters used in the model, and the parametrical uncertainties were assessed based on the responsive changes of the estimated erosion rates. Our results suggest that: (i) the performance/accuracy of the conversion models was largely dependent on the relative contributions of water vs. tillage erosion; and (ii) the estimated erosion rates were highly sensitive to the input values of the reference (137)Cs level, particle size correction factors and tillage depth. Guidelines were proposed to aid researchers in selecting and applying the conversion models under various situations common to agricultural landscapes.

  11. Preparation for Community Conversation: Recommendations for Iowa High Schools

    ERIC Educational Resources Information Center

    Wilkinson, David

    2005-01-01

    The task of a focused conversation and its facilitator is to release the genius, wisdom, and experience of the group on a topic and guide it towards a considered conclusion. Various purposes for holding a focused conversation on high schools and the recommendations of the Iowa Learns Council are: (1) Highlight the attention the community is…

  12. Shape-selective catalysis in dimethyl ether conversion

    SciTech Connect

    Sardesai, A.; Lee, S.

    1999-07-01

    Coal-derived syngas can be effectively converted to dimethyl ether (DME) in a single-stage, liquid-phase process. This Liquid Phase Dimethyl Ether (LPDME) process utilizes a dual catalytic system, which comprises of a physical blend between the methanol synthesis and the methanol dehydration catalyst slurried in an inert mineral oil. Such produced DME has vast potential as a building block chemical in the petrochemical industry to produce value-added specialty chemicals. The current research efforts are made to exploit the utilization of shape-selective catalysis using zeolites to produce targeted petrochemicals, including lower olefinic hydrocarbons. The catalysts probed in this investigation include zeolites of different physical, morphological, and chemical configurations. The effect of acidity of ZSM-5 type zeolites as well as the effect of the different channel size and orientation of the zeolites on product selectivity and catalyst deactivation are examined. Results obtained from experimentation of this study show that ZSM-5 type zeolite with low acidity (high SiO{sub 2}/Al{sub 2}O{sub 3} ratio, in this case 150) exhibits the highest selectivity towards lower (C{sub 2}-C{sub 4}) olefins in general. Controlled selectivity toward targeted olefinic species can be accomplished via devising catalytic reaction systems in such a way that the structural property of the catalyst and reactive interaction between molecules in the pores are geared toward formation of targeted molecular species which also at the same time prevent the formation of less desirable products. The internal morphology of the catalyst also has a pronounced effect on the deactivation phenomenon, where it is observed that zeolites possessing high acidity and a unidimensional channel structure are prone towards catalyst deactivation by coking and pore blockage.

  13. Study on High Conversion BWR with Island Type Fuel

    SciTech Connect

    Takao Kondo; Takaaki Mochida; Junichi Yamashita

    2002-07-01

    High Conversion Boiling Water Reactor (HCBWR) has been studied as one of the next generation BWRs. HCBWR can be improved by the use of Island Type Fuel to have inherently negative void coefficient. The proposed reactor concept also has the sustainability to extend LWR's period by about 180 years, and the compatibility with conventional BWR system that only substitution of fuel bundles and control rods are required. As an example case, High Conversion ABWR-II was evaluated here. (authors)

  14. Effects of Laboratory Videotaping Procedures on Selected Conversation Behaviors.

    ERIC Educational Resources Information Center

    Wiemann, John M.

    1981-01-01

    Concludes that in the laboratory, participants' conversation behavior is not discernably affected by videotaping, no matter how overt or obvious the taping procedure is. Study focuses on behaviors out of conscious awareness: gestures, head nods, speaking turns, self or object manipulations, and shifts to reclining posture or to forward lean. (PD)

  15. Materials for high-temperature thermoelectric conversion

    NASA Technical Reports Server (NTRS)

    Feigelson, R. S.; Elwell, D.

    1983-01-01

    High boron materials of high efficiency for thermoelectric power generation and capable of prolonged operation at temperatures over 1200 C are discussed. Background theoretical studies indicated that the low carrier mobility of materials with beta boron and related structures is probably associated with the high density of traps. Experimental work was mainly concerned with silicon borides in view of promising data from European laboratories. A systematic study using structure determination and lattice constant measurements failed to confirm the existence of an SiBn phase. Only SiB6 and a solid solution of silicon in beta boron with a maximum solid solubility of 5.5-6 at % at 1650 C were found.

  16. Analysis Of Spectrally Selective Liquid Absorption Filters For Hybrid Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Chendo, M. A. C.; Osborn, D. E.; Swenson, Rick

    1985-12-01

    Various techniques have been proposed to convert solar energy to both electric power and heat in hybrid systems. Many of these approaches are designed to utilize spectral selectivity to improve the overall conversion efficiency. Examples include spectrally selective beamsplitters and arrangements of long-wave or short-wave-pass glass filters that divide the spectrum so that photon energies are roughly matched to the energies corresponding to the solar-cell bandgaps or to efficient photothermal convertors. This paper describes the analysis of liquid optical filters that have high transmittance in the visible spectrum and high absorptance in the infrared. These qualities make it possible to capture that portion of the spectrum useful to a quantum convertor, such as a photovoltaic cell, while channeling the "excess heat" of the photons with energies below the bandgap to a thermal convertor, thereby enhancing the overall conversion efficiency of the system. The preliminary studies show that spectral responses of the tested solutions (salts in water) are primarily influenced by the cation component of the salt solution. By changing the solutions and concentrations, a variety of spectrally selective filters can be tailored to match system requirements.

  17. High Selectivity Oxygen Delignification

    SciTech Connect

    Lucian A. Lucia

    2005-11-15

    Project Objective: The objectives of this project are as follows: (1) Examine the physical and chemical characteristics of a partner mill pre- and post-oxygen delignified pulp and compare them to lab generated oxygen delignified pulps; (2) Apply the chemical selectivity enhancement system to the partner pre-oxygen delignified pulps under mill conditions (with and without any predetermined amounts of carryover) to determine how efficiently viscosity is preserved, how well selectivity is enhanced, if strength is improved, measure any yield differences and/or bleachability differences; and (3) Initiate a mill scale oxygen delignification run using the selectivity enhancement agent, collect the mill data, analyze it, and propose any future plans for implementation.

  18. A Conversation with Randy Asher, Principal of New York City's Brooklyn Technical High School

    ERIC Educational Resources Information Center

    Asher, Randy J.

    2016-01-01

    This is a conversation with Randy Asher, principal of New York City's Brooklyn Technical High School. Brooklyn Tech is a selective science high school in New York City, founded in 1922 as a school for boys with potential for careers in engineering and applied science. Today, it provides full-time education for both male and female students from…

  19. A Conversation with Randy Asher, Principal of New York City's Brooklyn Technical High School

    ERIC Educational Resources Information Center

    Asher, Randy J.

    2016-01-01

    This is a conversation with Randy Asher, principal of New York City's Brooklyn Technical High School. Brooklyn Tech is a selective science high school in New York City, founded in 1922 as a school for boys with potential for careers in engineering and applied science. Today, it provides full-time education for both male and female students from…

  20. High Temperature Magnetics for Power Conversion

    DTIC Science & Technology

    2005-06-01

    report. This document is the final report. 5 2.5 MAGNETICS, INC APPROACH TO MATERIAL DEVELOPMENT Background Manganese- zinc ferrites exist...density, high Curie temperatures and low core loss under specified conditions were the most desired properties. While manganese- zinc ferrites possess...in our laboratory from a blend of iron, manganese, and zinc oxides. Standard ferrite powder processing techniques were used. The starting

  1. The effect of selective solvent absorption on coal conversion. Final technical report

    SciTech Connect

    Larsen, J.W.

    1993-11-01

    Using a pair of different recycle oils from Wilsonville and {sup 1}H NMR, {sup 13}C NMR, gel permeation (GPC) chromatography, high pressure liquid chromatography (HPLC), and elemental analysis, no significant differences were observed between the composition of the recycle oil and that portion of the oil not absorbed by the coal. For these complex mixtures, coals are not selective absorbants. Since most of the heteroatoms responsible for most of the specific interactions have been removed by hydrogenolyses, this is perhaps not surprising. To address the issue of the role of hydrogen bond donors in the reused as hydrogen donor coal, tetralin and 2-t-butyltetralin were used as hydrogen donor solvents. This work is reported in detail in Section 2. The basic idea is that the presence of the t-butyl group on the aromatic ring will hinder or block diffusion of the hydrogen donor into the coal resulting in lower conversions and less hydrogen transferred with 2-t-butyltetralin than with tetralin. Observed was identical amounts of hydrogen transfer and nearly identical conversions to pyridine solubles for both hydrogen donors. Diffusion of hydrogen donors into the coal does not seem to play a significant role in coal conversion. Finally, in Section 3 is discussed the unfavorable impact on conversion of the structural rearrangements which occur when Illinois No. 6 coal is swollen with a solvent. We believe this rearrangement results in a more strongly associated solid leading to the diminution of coal reactions. Hydrogen donor diffusion does not seem to be a major factor in coal conversion while the structural rearrangement does. Both areas warrant further exploration.

  2. Conversion Tower for Dispatchable Solar Power: High-Efficiency Solar-Electric Conversion Power Tower

    SciTech Connect

    2012-01-11

    HEATS Project: Abengoa Solar is developing a high-efficiency solar-electric conversion tower to enable low-cost, fully dispatchable solar energy generation. Abengoa’s conversion tower utilizes new system architecture and a two-phase thermal energy storage media with an efficient supercritical carbon dioxide (CO2) power cycle. The company is using a high-temperature heat-transfer fluid with a phase change in between its hot and cold operating temperature. The fluid serves as a heat storage material and is cheaper and more efficient than conventional heat-storage materials, like molten salt. It also allows the use of a high heat flux solar receiver, advanced high thermal energy density storage, and more efficient power cycles.

  3. Low to high temperature energy conversion system

    NASA Technical Reports Server (NTRS)

    Miller, C. G. (Inventor)

    1977-01-01

    A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

  4. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    NASA Astrophysics Data System (ADS)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-12-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

  5. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    PubMed Central

    Zečević, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2016-01-01

    The ability to precisely control nanoscale features is increasingly exploited to develop and improve monofunctional catalysts1–4. Striking effects might also be expected in the case of bifunctional catalysts, which play an important role in hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel5–7. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called ‘intimacy criterion’8 has dictated the maximum distance between the two site types beyond which catalytic activity decreases. The lack of synthesis and material characterization methods with nanometer precision has long prevented in-depth exploration of the criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites8–11. Here we show for a bifunctional catalyst, comprised of an intimate mixture of zeolite Y and alumina binder and with platinum (Pt) metal controllably deposited20,21 on either the zeolite or the binder, that close proximity between metal and zeolite acid sites can be detrimental: the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains Pt on the binder, i.e. with a larger distance between metal and acid sites. Cracking of the large and complex hydrocarbon molecules typically derived from alternative sources such as gas-to-liquid technology, vegetable oil or algal oil6–7 should thus benefit especially from bifunctional catalysts that avoid locating Pt on the zeolite as the traditionally assumed optimal location. More generally, we anticipate that the ability to spatially organize different active sites at the nanoscale demonstrated here will benefit the further development and optimization of the newly emerging generation of multifunctional catalysts12–15. PMID:26659185

  6. Highly sensitive direct conversion ultrasound interferometer

    NASA Astrophysics Data System (ADS)

    Svitelskiy, Oleksiy; Grossmann, John; Suslov, Alexey

    2015-03-01

    Being invented more than fifty years ago, the ultrasonic pulse-echo technique has proven itself as a valuable and indispensable non-destructive tool to explore elastic properties of materials in engineering and scientific tasks. We propose a new design for the instrument based on mass-produced integral microchips. In our design the radiofrequency echo-pulse signal is processed by AD8302 RF gain and phase detector (www.analog.com).Its phase output is linearly proportional to the phase difference between the exciting and response signals. The gain output is proportional to the log of the ratio of amplitudes of the received to the exciting signals. To exclude the non-linear fragments and to enable exploring large phase changes, we employ parallel connection of two detectors, fed by in-phase and quadrature signals respectively. The instrument allowed us exploring phase transitions with precision of ΔV / V ~10-7 (V is the ultrasound speed). The high sensitivity of the logarithmic amplifiers embedded into AD8302 requires good grounding and screening of the receiving circuitry.

  7. Process for chemical reaction of amino acids and amides yielding selective conversion products

    DOEpatents

    Holladay, Jonathan E.

    2006-05-23

    The invention relates to processes for converting amino acids and amides to desirable conversion products including pyrrolidines, pyrrolidinones, and other N-substituted products. L-glutamic acid and L-pyroglutamic acid provide general reaction pathways to numerous and valuable selective conversion products with varied potential industrial uses.

  8. A high-efficiency energy conversion system

    SciTech Connect

    Belcher, A.E.

    1996-12-31

    A fundamentally new method for converting pressure into rotative motion is introduced. A historical background is given and an idealized non-turbine Brayton cycle engine and associated equations are described. Salient features are explained, together with suggested applications. Concerns over global warming, unacceptable levels of air pollution, and the need for more efficient utilization of nonrenewable energy resources, are issues which continue to plague us. The situation is further exacerbated by the possibility that underdeveloped countries, under pressure to expand their economies, might adopt power generating systems which could produce high levels of emissions. This scenario could easily develop if equipment, which once complied with stringent standards, failed to be adequately maintained through the absence of a reliable technical infrastructure. The Brayton cycle manometric engine has the potential for eliminating, or at least mitigating, many of the above issues. It is therefore of considerable importance to all populations, irrespective of demographic or economic considerations. This engine is inherently simple--the engine proper has only one moving part. It has no pistons, vanes, or other such conventional occlusive devices, yet it is a positive displacement machine. Sealing is achieved by what can best be described as a series of traveling U-tube manometers. Its construction does not require precision engineering nor the use of exotic materials, making it easy to maintain with the most rudimentary resources. Rotational velocity is low, and its normal life cycle is expected to extend to several decades. These advantages more than offset the machine`s large size. It is suited only to large and medium-scale stationary applications.

  9. High lift selected concepts

    NASA Technical Reports Server (NTRS)

    Henderson, M. L.

    1979-01-01

    The benefits to high lift system maximum life and, alternatively, to high lift system complexity, of applying analytic design and analysis techniques to the design of high lift sections for flight conditions were determined and two high lift sections were designed to flight conditions. The influence of the high lift section on the sizing and economics of a specific energy efficient transport (EET) was clarified using a computerized sizing technique and an existing advanced airplane design data base. The impact of the best design resulting from the design applications studies on EET sizing and economics were evaluated. Flap technology trade studies, climb and descent studies, and augmented stability studies are included along with a description of the baseline high lift system geometry, a calculation of lift and pitching moment when separation is present, and an inverse boundary layer technique for pressure distribution synthesis and optimization.

  10. Isotope separation by selective charge conversion and field deflection

    DOEpatents

    Hickman, Robert G.

    1978-01-01

    A deuterium-tritium separation system wherein a source beam comprised of positively ionized deuterium (D.sup.+) and tritium (T.sup.+) is converted at different charge-exchange cell sections of the system to negatively ionized deuterium (D.sup.-) and tritium (T.sup.-). First, energy is added to the beam to accelerate the D.sup.+ ions to the velocity that is optimum for conversion of the D.sup.+ ions to D.sup.- ions in a charge-exchange cell. The T.sup.+ ions are accelerated at the same time, but not to the optimum velocity since they are heavier than the D.sup.+ ions. The T.sup.+ ions are, therefore, not converted to T.sup.- ions when the D.sup.+ ions are converted to D.sup.- ions. This enables effective separation of the beam by deflection of the isotopes with an electrostatic field, the D.sup.- ions being deflected in one direction and the T.sup.+ ions being deflected in the opposite direction. Next, more energy is added to the deflected beam of T.sup.+ ions to bring the T.sup.+ ions to the optimum velocity for their conversion to T.sup.- ions. In a particular use of the invention, the beams of D.sup.- and T.sup.- ions are separately further accelerated and then converted to energetic neutral particles for injection as fuel into a thermonuclear reactor. The reactor exhaust of D.sup.+ and T.sup.+ and the D.sup.+ and T.sup.+ that was not converted in the respective sections is combined with the source beam and recycled through the system to increase the efficiency of the system.

  11. Advanced materials for high-temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Vining, Cronin B.; Vandersande, Jan W.; Wood, Charles

    1992-01-01

    A number of refractory semiconductors are under study at the Jet Propulsion Laboratory for application in thermal to electric energy conversion for space power. The main thrust of the program is to improve or develop materials of high figure of merit and, therefore, high conversion efficiencies over a broad temperature range. Materials currently under investigation are represented by silicon-germanium alloys, lanthanum telluride, and boron carbide. The thermoelectric properties of each of these materials, and prospects for their further improvements, are discussed. Continued progress in thermoelectric materials technology can be expected to yield reliable space power systems with double to triple the efficiency of current state of the art systems.

  12. Advanced materials for high-temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Vining, Cronin B.; Vandersande, Jan W.; Wood, Charles

    1992-01-01

    A number of refractory semiconductors are under study at the Jet Propulsion Laboratory for application in thermal to electric energy conversion for space power. The main thrust of the program is to improve or develop materials of high figure of merit and, therefore, high conversion efficiencies over a broad temperature range. Materials currently under investigation are represented by silicon-germanium alloys, lanthanum telluride, and boron carbide. The thermoelectric properties of each of these materials, and prospects for their further improvements, are discussed. Continued progress in thermoelectric materials technology can be expected to yield reliable space power systems with double to triple the efficiency of current state of the art systems.

  13. High Selectivity Oxygen Delignification

    SciTech Connect

    Arthur J. Ragauskas Lucian A. Lucia Hasan Jameel

    2005-09-30

    The overall objective of this program was to develop improved extended oxygen delignification (EOD) technologies for current U.S. pulp mill operations. This was accomplished by: (1) Identifying pulping conditions that optimize O and OO performance; (2) Identifying structural features of lignin that enhance reactivity towards EOD of high kappa pulps; (3) Identifying factors minimizing carbohydrate degradation and improve pulp strength of EOD high kappa pulps; (4) Developing a simple, reproducible method of quantifying yield gains from EOD; and (5) Developing process conditions that significantly reduce the capital requirements of EOD while optimizing the yield benefits. Key research outcomes included, demonstrating the use of a mini-O sequence such as (E+O)Dkf:0.05(E+O) or Dkf:0.05(E+O)(E+O) without interstage washing could capture approximately 60% of the delignification efficiency of a conventional O-stage without the major capital requirements associated with an O-stage for conventional SW kraft pulps. The rate of formation and loss of fiber charge during an O-stage stage can be employed to maximize net fiber charge. Optimal fiber charge development and delignification are two independent parameters and do not parallel each other. It is possible to utilize an O-stage to enhance overall cellulosic fiber charge of low and high kappa SW kraft pulps which is beneficial for physical strength properties. The application of NIR and multi-variant analysis was developed into a rapid and simple method of determining the yield of pulp from an oxygen delignification stage that has real-world mill applications. A focus point of this program was the demonstration that Kraft pulping conditions and oxygen delignification of high and low-kappa SW and HW pulps are intimately related. Improved physical pulp properties and yield can be delivered by controlling the H-factor and active alkali charge. Low AA softwood kraft pulp with a kappa number 30 has an average improvement of 2% in

  14. Current status of high conversion pressurized water reactor design studies

    SciTech Connect

    Umeoka, T.; Kono, T.; Toyoda, Y.; Ogino, M.; Iwai, S.; Hishida, H.

    1988-01-01

    Preliminary design studies on high conversion pressurized water reactors (HCPWRs) have been completed, and plant design studies are currently being performed to improve the feasibility of HCPWRs. The present status of the feasibility studies is covered, and the related validation tests to be conducted in the coming years are reviewed.

  15. Internal conversion in highly-stripped {sup 83}Kr ions

    SciTech Connect

    Rehm, K.E.; Ahmad, I.; Gehring, J.

    1995-08-01

    The transition probability per unit time for the decay of a nuclear level via internal conversion (IC), {lambda}IC, depends on the electron environment of the nucleus. For example, inner-shell conversion in highly-charged ions can change appreciably as electrons are successively removed from the ion. Magnetic dipole (Ml) transitions are especially sensitive to this effect since the internal conversion depends strongly on the electron density at the nucleus. Hence, measurements of {lambda}IC,q, the internal conversion rate in an ion with charge state q, can provide good tests of theoretical electron wave functions if the electron configuration in the ions is known. In a previous experiment, a new method which identifies charge-changing events during passage of ion beams through a magnetic spectrometer was used to determine {lambda}IC,q for the 14.4-keV isomer in {sup 57}Fe. This contribution reports measurements made using the same technique for the 9.4-keV isomer in {sup 83}Kr. A beam of {sup 83}Kr with energy 650 MeV bombarded a Au target with a thickness 300 {mu}g cm{sup -2}. Secondary scattered beams were accepted and analyzed by an Enge magnetic spectrometer. The numbers of excited nuclei decaying during passage through the spectrometer and their internal conversion rates were deduced from the pattern of events measured in the spectrometer focal plane.

  16. Conversion of direct process high-boiling residue to monosilanes

    DOEpatents

    Brinson, Jonathan Ashley; Crum, Bruce Robert; Jarvis, Jr., Robert Frank

    2000-01-01

    A process for the production of monosilanes from the high-boiling residue resulting from the reaction of hydrogen chloride with silicon metalloid in a process typically referred to as the "direct process." The process comprises contacting a high-boiling residue resulting from the reaction of hydrogen chloride and silicon metalloid, with hydrogen gas in the presence of a catalytic amount of aluminum trichloride effective in promoting conversion of the high-boiling residue to monosilanes. The present process results in conversion of the high-boiling residue to monosilanes. At least a portion of the aluminum trichloride catalyst required for conduct of the process may be formed in situ during conduct of the direct process and isolation of the high-boiling residue.

  17. High resolution A/D conversion based on piecewise conversion at lower resolution

    DOEpatents

    Terwilliger, Steve [Albuquerque, NM

    2012-06-05

    Piecewise conversion of an analog input signal is performed utilizing a plurality of relatively lower bit resolution A/D conversions. The results of this piecewise conversion are interpreted to achieve a relatively higher bit resolution A/D conversion without sampling frequency penalty.

  18. High efficiency GaP power conversion for Betavoltaic applications

    NASA Technical Reports Server (NTRS)

    Sims, Paul E.; Dinetta, Louis C.; Barnett, Allen M.

    1994-01-01

    AstroPower is developing a gallium phosphide (GaP) based energy converter optimized for radio luminescent light-based power supplies. A 'two-step' or 'indirect' process is used where a phosphor is excited by radioactive decay products to produce light that is then converted to electricity by a photovoltaic energy converter. This indirect conversion of beta-radiation to electrical energy can be realized by applying recent developments in tritium based radio luminescent (RL) light sources in combination with the high conversion efficiencies that can be achieved under low illumination with low leakage, gallium phosphide based devices. This tritium to light approach is inherently safer than battery designs that incorporate high activity radionuclides because the beta particles emitted by tritium are of low average energy and are easily stopped by a thin layer of glass. GaP layers were grown by liquid phase epitaxy and p/n junction devices were fabricated and characterized for low light intensity power conversion. AstroPower has demonstrated the feasibility of the GaP based energy converter with the following key results: 23.54 percent conversion efficiency under 968 muW/sq cm 440 nm blue light, 14.59 percent conversion efficiency for 2.85 muW/sq cm 440 nm blue light, and fabrication of working 5 V array. We have also determined that at least 20 muW/sq cm optical power is available for betavoltaic power systems. Successful developments of this device is an enabling technology for low volume, safe, high voltage, milliwatt power supplies with service lifetimes in excess of 12 years.

  19. High efficiency GaP power conversion for Betavoltaic applications

    NASA Astrophysics Data System (ADS)

    Sims, Paul E.; Dinetta, Louis C.; Barnett, Allen M.

    1994-09-01

    AstroPower is developing a gallium phosphide (GaP) based energy converter optimized for radio luminescent light-based power supplies. A 'two-step' or 'indirect' process is used where a phosphor is excited by radioactive decay products to produce light that is then converted to electricity by a photovoltaic energy converter. This indirect conversion of beta-radiation to electrical energy can be realized by applying recent developments in tritium based radio luminescent (RL) light sources in combination with the high conversion efficiencies that can be achieved under low illumination with low leakage, gallium phosphide based devices. This tritium to light approach is inherently safer than battery designs that incorporate high activity radionuclides because the beta particles emitted by tritium are of low average energy and are easily stopped by a thin layer of glass. GaP layers were grown by liquid phase epitaxy and p/n junction devices were fabricated and characterized for low light intensity power conversion. AstroPower has demonstrated the feasibility of the GaP based energy converter with the following key results: 23.54 percent conversion efficiency under 968 muW/sq cm 440 nm blue light, 14.59 percent conversion efficiency for 2.85 muW/sq cm 440 nm blue light, and fabrication of working 5 V array. We have also determined that at least 20 muW/sq cm optical power is available for betavoltaic power systems. Successful developments of this device is an enabling technology for low volume, safe, high voltage, milliwatt power supplies with service lifetimes in excess of 12 years.

  20. Preliminary Neutronic Study of D2O-cooled High Conversion PWRs

    SciTech Connect

    Hikaru Hiruta; Gilles Youinou

    2013-10-01

    This paper presents a preliminary neutronics analysis of tight-pitch D2O-cooled high-conversion PWRs loaded with MOX fuel aiming at high Pu conversion and negative void coefficient. SCALE6.1 has been exclusively utilized for this study. The analyses are performed in two separate parts. The first part of this paper investigates the performance of axial and internal blankets and seeks break-even or near-breeder core even without the presence of radial blankets. The second part of this paper performs sensitivity and uncertainty analyses of integral parameters (keff and void coefficient) for selected systems in order to analyze the characters of this high-conversion PWR from different aspects.

  1. Mode-selective wavelength conversion of OFDM-QPSK signals in a multimode silicon waveguide.

    PubMed

    Qiu, Ying; Li, Xiang; Luo, Ming; Chen, Daigao; Wang, Jiamin; Xu, Jing; Yang, Qi; Yu, Shaohua

    2017-02-20

    We experimentally demonstrate on-chip mode-selective wavelength conversions based on the degenerate four-wave mixing (FWM) nonlinear effect in a few-mode silicon waveguide. A multimode waveguide with tapered directional coupler based mode (de)multiplexers is designed and fabricated. Using signals with advanced modulation formats all-optical wavelength conversions of 102.6-Gb/s OFDM-QPSK signals are verified. Experimental results show that only small optical signal-to-noise ratio (OSNR) penalties are observed after wavelength conversion of both modes, which are less than 2 dB for OFDM-QPSK at 7% forward error correction (FEC) threshold.

  2. Efficient and selective molecular catalyst for the CO2-to-CO electrochemical conversion in water

    PubMed Central

    Costentin, Cyrille; Robert, Marc; Savéant, Jean-Michel; Tatin, Arnaud

    2015-01-01

    Substitution of the four paraphenyl hydrogens of iron tetraphenylporphyrin by trimethylammonio groups provides a water-soluble molecule able to catalyze the electrochemical conversion of carbon dioxide into carbon monoxide. The reaction, performed in pH-neutral water, forms quasi-exclusively carbon monoxide with very little production of hydrogen, despite partial equilibration of CO2 with carbonic acid—a low pKa acid. This selective molecular catalyst is endowed with a good stability and a high turnover frequency. On this basis, prescribed composition of CO–H2 mixtures can be obtained by adjusting the pH of the solution, optionally adding an electroinactive buffer. The development of these strategies will be greatly facilitated by the fact that one operates in water. The same applies for the association of the cathode compartment with a proton-producing anode by means of a suitable separator. PMID:26038542

  3. Frequency conversion of high-intensity, femtosecond laser pulses

    SciTech Connect

    Banks, P S

    1997-06-01

    Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated

  4. Commercial approaches to genetic selection for growth and feed conversion in domestic poultry.

    PubMed

    Emmerson, D A

    1997-08-01

    Tremendous genetic progress has been observed historically for growth and feed conversion through the efforts of the primary breeding companies. However, significant between-strain variation still exists due to differences in selection emphasis and selection techniques practiced by these organizations. This paper provides an overview of methods currently employed in commercial poultry breeding with reference to factors complicating program design and future challenges facing the industry. Mass selection for body weight has resulted in a significant reduction in the number of days required to grow bird to market weight with indirect improvements in feed conversion. Direct selection for feed conversion is accomplished through part record testing of males that have been preselected for body weight, conformation, and defect traits. Data are commonly subjected to complex statistical analysis both to correct feed conversion for variation in body weight and to improve the accuracy of breeding value estimates. Feed conversion breeding values of male sibs are sometimes used for the selection of female candidates as well. Selection for growth rate and efficiency has resulted in negative complications, such as ascites, reduced reproductive performance, skeletal abnormalities, and increased carcass fatness. Some of these factors may be partially ameliorated through modified selection practices. If not addressed by the breeding industry, the disruption of physiological homeostasis might ultimately represent economic and genetic barriers to further progress in improving growth and efficiency. Modern techniques in molecular genetics, utilized in conjunction with traditional quantitative genetic approaches, will provide additional opportunities to circumvent these physiological complications associated with genetic selection for growth and feed efficiency.

  5. Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion.

    PubMed

    Thomas, Nathan H; Chen, Zhen; Fan, Shanhui; Minnich, Austin J

    2017-07-13

    Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In field tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. With straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat.

  6. Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion

    DOE PAGES

    Thomas, Nathan H.; Chen, Zhen; Fan, Shanhui; ...

    2017-07-13

    Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we then report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In fieldmore » tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. Furthemore, with straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat« less

  7. The impact of laws on metric conversion: A survey of selected large US corporations

    NASA Astrophysics Data System (ADS)

    1982-02-01

    The purpose of the study was to determine the extent to which a sample of the Fortune 1000 firms perceived that legal impediments to metric conversion exists. The Fortune 1000 firms included in the study were: (a) the 41 firms which identified legal impediments to metric conversion in an earlier study report commissioned by the Board, U.S. Metric Board 1979 Survey of Selected Large U.S. Firms and Industries; and (b) 10 additional firms from the industry groups indicating some problems with laws and regulations. This study attempted to make several determinations among which were: whether or not legal impediments or perceptions of legal impediments to metric conversion exist; the correlation between metric planning and the perception that impediments exist; the distribution of perceived impediments among Federal, State and local laws; the nature of corporate lobbying activities; and corporate experiences in addressing legal impediments to conversion.

  8. Irradiation Tests Supporting LEU Conversion of Very High Power Research Reactors in the US

    SciTech Connect

    Woolstenhulme, N. E.; Cole, J. I.; Glagolenko, I.; Holdaway, K. K.; Housley, G. K.; Rabin, B. H.

    2016-10-01

    The US fuel development team is developing a high density uranium-molybdenum alloy monolithic fuel to enable conversion of five high-power research reactors. Previous irradiation tests have demonstrated promising behavior for this fuel design. A series of future irradiation tests will enable selection of final fuel fabrication process and provide data to qualify the fuel at moderately-high power conditions for use in three of these five reactors. The remaining two reactors, namely the Advanced Test Reactor and High Flux Isotope Reactor, require additional irradiation tests to develop and demonstrate the fuel’s performance with even higher power conditions, complex design features, and other unique conditions. This paper reviews the program’s current irradiation testing plans for these moderately-high irradiation conditions and presents conceptual testing strategies to illustrate how subsequent irradiation tests will build upon this initial data package to enable conversion of these two very-high power research reactors.

  9. Survey of pain specialists regarding conversion of high-dose intravenous to neuraxial opioids

    PubMed Central

    Gorlin, Andrew W; Rosenfeld, David M; Maloney, Jillian; Wie, Christopher S; McGarvey, Johnathan; Trentman, Terrence L

    2016-01-01

    The conversion of high-dose intravenous (IV) opioids to an equianalgesic epidural (EP) or intrathecal (IT) dose is a common clinical dilemma for which there is little evidence to guide practice. Expert opinion varies, though a 100 IV:10:EP:1 IT conversion ratio is commonly cited in the literature, especially for morphine. In this study, the authors surveyed 724 pain specialists to elucidate the ratios that respondents apply to convert high-dose IV morphine, hydromorphone, and fentanyl to both EP and IT routes. Eighty-three respondents completed the survey. Conversion ratios were calculated and entered into graphical scatter plots. The data suggest that there is wide variation in how pain specialists convert high-dose IV opioids to EP and IT routes. The 100 IV:10 EP:1 IT ratio was the most common answer of survey respondent, especially for morphine, though also for hydromorphone and fentanyl. Furthermore, more respondents applied a more aggressive conversion strategy for hydromorphone and fentanyl, likely reflecting less spinal selectivity of those opioids compared with morphine. The authors conclude that there is little consensus on this issue and suggest that in the absence of better data, a conservative approach to opioid conversion between IV and neuraxial routes is warranted. PMID:27703394

  10. Survey of pain specialists regarding conversion of high-dose intravenous to neuraxial opioids.

    PubMed

    Gorlin, Andrew W; Rosenfeld, David M; Maloney, Jillian; Wie, Christopher S; McGarvey, Johnathan; Trentman, Terrence L

    2016-01-01

    The conversion of high-dose intravenous (IV) opioids to an equianalgesic epidural (EP) or intrathecal (IT) dose is a common clinical dilemma for which there is little evidence to guide practice. Expert opinion varies, though a 100 IV:10:EP:1 IT conversion ratio is commonly cited in the literature, especially for morphine. In this study, the authors surveyed 724 pain specialists to elucidate the ratios that respondents apply to convert high-dose IV morphine, hydromorphone, and fentanyl to both EP and IT routes. Eighty-three respondents completed the survey. Conversion ratios were calculated and entered into graphical scatter plots. The data suggest that there is wide variation in how pain specialists convert high-dose IV opioids to EP and IT routes. The 100 IV:10 EP:1 IT ratio was the most common answer of survey respondent, especially for morphine, though also for hydromorphone and fentanyl. Furthermore, more respondents applied a more aggressive conversion strategy for hydromorphone and fentanyl, likely reflecting less spinal selectivity of those opioids compared with morphine. The authors conclude that there is little consensus on this issue and suggest that in the absence of better data, a conservative approach to opioid conversion between IV and neuraxial routes is warranted.

  11. Selective homogeneous and heterogeneous catalytic conversion of methanol/dimethyl ether to triptane.

    PubMed

    Hazari, Nilay; Iglesia, Enrique; Labinger, Jay A; Simonetti, Dante A

    2012-04-17

    The demand for specific fuels and chemical feed-stocks fluctuates, and as a result, logistical mismatches can occur in the supply of their precursor raw materials such as coal, biomass, crude oil, and methane. To overcome these challenges, industry requires a versatile and robust suite of conversion technologies, many of which are mediated by synthesis gas (CO + H(2)) or methanol/dimethyl ether (DME) intermediates. One such transformation, the conversion of methanol/DME to triptane (2,2,3-trimethylbutane) has spurred particular research interest. Practically, triptane is a high-octane, high-value fuel component, but this transformation also raises fundamental questions: how can such a complex molecule be generated from such a simple precursor with high selectivity? In this Account, we present studies of this reaction carried out in two modes: homogeneously with soluble metal halide catalysts and heterogeneously over solid microporous acid catalysts. Despite their very different compositions, reaction conditions, provenance, and historical scientific context, both processes lead to remarkably similar products and mechanistic interpretations. In both cases, hydrocarbon chains grow by successive methylation in a carbocation-based mechanism. The relative rates of competitive processes-chain growth by methylation, chain termination by hydrogen transfer, isomerization, and cracking-systematically depend upon the structure of the various hydrocarbons produced, strongly favoring the formation of the maximally branched C(7) alkane, triptane. The two catalysts also show parallels in their dependence on acid strength. Stronger acids exhibit higher methanol/DME conversion but also tend to favor chain termination, isomerization, and cracking relative to chain growth, decreasing the preference for triptane. Hence, in both modes, there will be an optimal range: if the acid strength is too low, activity will be poor, but if it is too high, selectivity will be poor. A related

  12. Conversion Total Knee Arthroplasty after Failed High Tibial Osteotomy

    PubMed Central

    Song, Sang Jun; Kim, Kang Il; Lee, Chung Hwan

    2016-01-01

    Clinical results of high tibial osteotomy (HTO) deteriorate over time despite the initial satisfactory results. Several knees may require a conversion to total knee arthroplasty (TKA) because of failure such as the progression of degenerative osteoarthritis and the loss of the correction angle. It is important to know the long-term survival rate and common reason of failure in HTO to inform patients of postoperative expectations before surgery and to prevent surgical errors during surgery. In addition, it has been reported that clinical and radiological results, revision rate, and complication rate were poorer than those in patients without a previous HTO. There are few review articles that describe why conversion TKA after HTO is surgically difficult and the results are poor. Surgeons have to avoid the various complications and surgical errors in this specific situation. We would like to present the considering factors and technical difficulties during conversion TKA after HTO with a review of the literature. We could conclude through the review that the correction of deformity, lower amount of tibial bone resection, and sufficient polyethylene insert thickness, restoration of the joint line height, and adequate ligament balancing can be helpful in overcoming the technical challenges encountered during TKA following HTO. PMID:27274465

  13. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    SciTech Connect

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  14. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    DOE PAGES

    Ramasamy, Karthikeyan K.; Gray, Michel; Job, Heather; ...

    2016-02-03

    Here, a highly versatile ethanol conversion process to selectively generate high value compounds is presented here. By changing the reaction temperature, ethanol can be selectively converted to >C2 alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3 catalyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensation or the acetone formation is the path taken in changing the product composition. This article contains the catalytic activity comparison between the mono-functional and physical mixture counterpart to the hydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  15. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    SciTech Connect

    Ramasamy, Karthikeyan K.; Gray, Michel; Job, Heather; Smith, Colin; Wang, Yong

    2016-02-03

    Here, a highly versatile ethanol conversion process to selectively generate high value compounds is presented here. By changing the reaction temperature, ethanol can be selectively converted to >C2 alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3 catalyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensation or the acetone formation is the path taken in changing the product composition. This article contains the catalytic activity comparison between the mono-functional and physical mixture counterpart to the hydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  16. Hard Selective Sweep and Ectopic Gene Conversion in a Gene Cluster Affording Environmental Adaptation

    PubMed Central

    Trampczynska, Aleksandra; Bernal, María; Motte, Patrick; Clemens, Stephan; Krämer, Ute

    2013-01-01

    Among the rare colonizers of heavy-metal rich toxic soils, Arabidopsis halleri is a compelling model extremophile, physiologically distinct from its sister species A. lyrata, and A. thaliana. Naturally selected metal hypertolerance and extraordinarily high leaf metal accumulation in A. halleri both require Heavy Metal ATPase4 (HMA4) encoding a PIB-type ATPase that pumps Zn2+ and Cd2+ out of specific cell types. Strongly enhanced HMA4 expression results from a combination of gene copy number expansion and cis-regulatory modifications, when compared to A. thaliana. These findings were based on a single accession of A. halleri. Few studies have addressed nucleotide sequence polymorphism at loci known to govern adaptations. We thus sequenced 13 DNA segments across the HMA4 genomic region of multiple A. halleri individuals from diverse habitats. Compared to control loci flanking the three tandem HMA4 gene copies, a gradual depletion of nucleotide sequence diversity and an excess of low-frequency polymorphisms are hallmarks of positive selection in HMA4 promoter regions, culminating at HMA4-3. The accompanying hard selective sweep is segmentally eclipsed as a consequence of recurrent ectopic gene conversion among HMA4 protein-coding sequences, resulting in their concerted evolution. Thus, HMA4 coding sequences exhibit a network-like genealogy and locally enhanced nucleotide sequence diversity within each copy, accompanied by lowered sequence divergence between paralogs in any given individual. Quantitative PCR corroborated that, across A. halleri, three genomic HMA4 copies generate overall 20- to 130-fold higher transcript levels than in A. thaliana. Together, our observations constitute an unexpectedly complex profile of polymorphism resulting from natural selection for increased gene product dosage. We propose that these findings are paradigmatic of a category of multi-copy genes from a broad range of organisms. Our results emphasize that enhanced gene product dosage

  17. Selective conversion of cellulose in corncob residue to levulinic acid in an aluminum trichloride-sodium chloride system.

    PubMed

    Li, Jianmei; Jiang, Zhicheng; Hu, Libin; Hu, Changwei

    2014-09-01

    Increased energy consumption and environmental concerns have driven efforts to produce chemicals from renewable biomass with high selectivity. Here, the selective conversion of cellulose in corncob residue, a process waste from the production of xylose, to levulinic acid was carried out using AlCl3 as catalyst and NaCl as promoter by a hydrothermal method at relatively low temperature. A levulinic acid yield of 46.8 mol% was obtained, and the total selectivity to levulinic acid with formic acid was beyond 90%. NaCl selectively promoted the dissolution of cellulose from corncob residue, and significantly improved the yield and selectivity to levulinic acid by inhibiting lactic acid formation in the subsequent dehydration process. Owing to the salt effect of NaCl, the obtained levulinic acid could be efficiently extracted to tetrahydrofuran from aqueous solution. The aqueous solution with AlCl3 and NaCl could be recycled 4 times. Because of the limited conversion of lignin, this process allows for the production of levulinic acid with high selectivity directly from corncob residue in a simple separation process.

  18. AMTEC: High efficiency static conversion for space power

    NASA Technical Reports Server (NTRS)

    Bankston, C. P.; Shirbacheh, M.

    1986-01-01

    Future manned and unmanned space missions will require reliable, high efficiency energy conversion systems. For a manned Mars mission, power levels in the range of 10 to 100 kWe will be needed. The Alkali Metal Thermoelectric Converter (AMTEC) is a direct energy conversion technology with the potential to meet these needs. The AMTEC is a thermally regenerative electrochemical device that derives its operation from the sodium ion conducting properties of beta-alumina solid electrolyte (BASE). To date, an efficiency of 19%, area power density of 1 W/sq cm, and a lifetime of 10,000 hours at high temperature were demonstrated in laboratory devices. Systems studies show that projected AMTEC systems equal or surpass the performance of other static or dynamic systems in applications of 1 kWe-1 MWe. Thus, the laboratory experiments and applications studies conducted to date have shown that the AMTEC posseses great potential. In order to bring this technology to the stage where prototype units can be built and operated, several technical issues must be addressed. These include the need for long life, high power electrodes, minimization of radiative parasitic losses, and high temperature seals. In summary, the evidence shows that if AMTEC is developed, it can play a significant role in future space power applications.

  19. All-optical wavelength conversion with monolithically integrated Mach-Zehnder interferometer SOA switches by selective area MOVPE

    NASA Astrophysics Data System (ADS)

    Song, Xueliang; Zhang, Zhenrui; Yit, Foo Cheong; Nakano, Yoshiaki

    2005-01-01

    We achieved first dynamic all-optical wavelength conversion in bandgap-engineered MZI SOA all-optical switch. Clear eye-diagram of 2.5Gbps wavelength conversion was confirmed. This is the first wavelength conversion demonstration with a bandgap-engineered PIC with either selective-area-growth and quantum-well-intermixing techniques.

  20. Selective Disclosure in a First Conversation about a Family Death in James Agee's Novel "A Death in the Family"

    ERIC Educational Resources Information Center

    Rober, Peter; Rosenblatt, Paul C.

    2013-01-01

    The first conversation of a family about a family death is a neglected but potentially important topic. In a first conversation in James Agee's (1957/2006) novel "A Death in the Family," the member who knows the most about the accidental death of another member discloses information selectively. The first conversation in Agee's novel suggests that…

  1. Selective Disclosure in a First Conversation about a Family Death in James Agee's Novel "A Death in the Family"

    ERIC Educational Resources Information Center

    Rober, Peter; Rosenblatt, Paul C.

    2013-01-01

    The first conversation of a family about a family death is a neglected but potentially important topic. In a first conversation in James Agee's (1957/2006) novel "A Death in the Family," the member who knows the most about the accidental death of another member discloses information selectively. The first conversation in Agee's novel suggests that…

  2. Ultra Wideband Polarization-Selective Conversions of Electromagnetic Waves by Metasurface under Large-Range Incident Angles

    PubMed Central

    Yin, Jia Yuan; Wan, Xiang; Zhang, Qian; Cui, Tie Jun

    2015-01-01

    We propose an ultra-wideband polarization-conversion metasurface with polarization selective and incident-angle insensitive characteristics using anchor-shaped units through multiple resonances. The broadband characteristic is optimized by the genetic optimization algorithm, from which the anchor-shaped unit cell generates five resonances, resulting in expansion of the operating frequency range. Owing to the structural feature of the proposed metasurface, only x- and y-polarized incident waves can reach high-efficiency polarization conversions, realizing the polarization-selective property. The proposed metasurface is also insensitive to the angle of incident waves, which indicates a promising future in modern communication systems. We fabricate and measure the proposed metasurface, and both the simulated and measured results show ultra-wide bandwidth for the x- and y-polarized incident waves. PMID:26202495

  3. Ultra Wideband Polarization-Selective Conversions of Electromagnetic Waves by Metasurface under Large-Range Incident Angles

    NASA Astrophysics Data System (ADS)

    Yin, Jia Yuan; Wan, Xiang; Zhang, Qian; Cui, Tie Jun

    2015-07-01

    We propose an ultra-wideband polarization-conversion metasurface with polarization selective and incident-angle insensitive characteristics using anchor-shaped units through multiple resonances. The broadband characteristic is optimized by the genetic optimization algorithm, from which the anchor-shaped unit cell generates five resonances, resulting in expansion of the operating frequency range. Owing to the structural feature of the proposed metasurface, only x- and y-polarized incident waves can reach high-efficiency polarization conversions, realizing the polarization-selective property. The proposed metasurface is also insensitive to the angle of incident waves, which indicates a promising future in modern communication systems. We fabricate and measure the proposed metasurface, and both the simulated and measured results show ultra-wide bandwidth for the x- and y-polarized incident waves.

  4. High pressure synthesis gas conversion. Task 3: High pressure profiles

    SciTech Connect

    Not Available

    1993-05-01

    The purpose of this research project was to build and test a high pressure fermentation system for the production of ethanol from synthesis gas. The fermenters, pumps, controls, and analytical system were procured or fabricated and assembled in our laboratory. This system was then used to determine the effects of high pressure on growth and ethanol production by C. 1jungdahlii. The limits of cell concentration and mass transport relationships were found in CSTR and immobilized cell reactors (ICR). The minimum retention times and reactor volumes were found for ethanol production in these reactors.

  5. RF System High Power Amplifier Software Conversion at Jefferson Lab

    SciTech Connect

    G. Lahti; H. Dong; T. Seegerger

    2006-10-31

    Jefferson Lab is in the process of converting the RF system from analog RF modules and non-smart high power amplifiers (HPAs) to digital RF modules and smart HPAs. The present analog RF module controls both the RF signal and the non-smart HPA hardware. The new digital RF module will only control the RF signal, so the new HPA must include embedded software. This paper will describe the conversion from a software perspective, including the initial testing, the intermediate mixed system of old and new units, and finally the totally new RF system.

  6. A Versatile Cu(II) Metal-Organic Framework Exhibiting High Gas Storage Capacity with Selectivity for CO2 : Conversion of CO2 to Cyclic Carbonate and Other Catalytic Abilities.

    PubMed

    De, Dinesh; Pal, Tapan K; Neogi, Subhadip; Senthilkumar, S; Das, Debasree; Gupta, Sayam Sen; Bharadwaj, Parimal K

    2016-03-01

    A linear tetracarboxylic acid ligand, H4 L, with a pendent amine moiety solvothermally forms two isostructural metal-organic frameworks (MOFs) LM (M=Zn(II) , Cu(II) ). Framework LCu can also be obtained from LZn by post- synthetic metathesis without losing crystallinity. Compared with LZn , the LCu framework exhibits high thermal stability and allows removal of guest solvent and metal-bound water molecules to afford the highly porous, LCu '. At 77 K, LCu ' absorbs 2.57 wt % of H2 at 1 bar, which increases significantly to 4.67 wt % at 36 bar. The framework absorbs substantially high amounts of methane (238.38 cm(3)  g(-1) , 17.03 wt %) at 303 K and 60 bar. The CH4 absorption at 303 K gives a total volumetric capacity of 166 cm(3)  (STP) cm(-3) at 35 bar (223.25 cm(3)  g(-1) , 15.95 wt %). Interestingly, the NH2 groups in the linker, which decorate the channel surface, allow a remarkable 39.0 wt % of CO2 to be absorbed at 1 bar and 273 K, which comes within the dominion of the most famous MOFs for CO2 absorption. Also, LCu ' shows pronounced selectivity for CO2 absorption over CH4 , N2 , and H2 at 273 K. The absorbed CO2 can be converted to value-added cyclic carbonates under relatively mild reaction conditions (20 bar, 120 °C). Finally, LCu ' is found to be an excellent heterogeneous catalyst in regioselective 1,3-dipolar cycloaddition reactions ("click" reactions) and provides an efficient, economic route for the one-pot synthesis of structurally divergent propargylamines through three-component coupling of alkynes, amines, and aldehydes.

  7. Tuning of Silver Catalyst Mesostructure Promotes Selective Carbon Dioxide Conversion into Fuels.

    PubMed

    Yoon, Youngmin; Hall, Anthony Shoji; Surendranath, Yogesh

    2016-12-05

    An electrode's performance for catalytic CO2 conversion to fuels is a complex convolution of surface structure and transport effects. Using well-defined mesostructured silver inverse opal (Ag-IO) electrodes, it is demonstrated that mesostructure-induced transport limitations alone serve to increase the turnover frequency for CO2 activation per unit area, while simultaneously improving reaction selectivity. The specific activity for catalyzed CO evolution systematically rises by three-fold and the specific activity for catalyzed H2 evolution systematically declines by ten-fold with increasing mesostructural roughness of Ag-IOs. By exploiting the compounding influence of both of these effects, we demonstrate that mesostructure, rather than surface structure, can be used to tune CO evolution selectivity from less than 5 % to more than 80 %. These results establish electrode mesostructuring as a powerful complementary tool for tuning both catalyst selectivity and efficiency for CO2 conversion into fuels.

  8. Refractory materials for high-temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.; Emin, D.

    1983-01-01

    Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.

  9. Refractory materials for high-temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, C.; Emin, D.

    1984-01-01

    Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimaiation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.

  10. Supervised and Unsupervised Feature Selection for Inferring Social Nature of Telephone Conversations from Their Content

    PubMed Central

    Stark, Anthony; Shafran, Izhak; Kaye, Jeffrey

    2012-01-01

    The ability to reliably infer the nature of telephone conversations opens up a variety of applications, ranging from designing context-sensitive user interfaces on smartphones, to providing new tools for social psychologists and social scientists to study and understand social life of different subpopulations within different contexts. Using a unique corpus of everyday telephone conversations collected from eight residences over the duration of a year, we investigate the utility of popular features, extracted solely from the content, in classifying business-oriented calls from others. Through feature selection experiments, we find that the discrimination can be performed robustly for a majority of the calls using a small set of features. Remarkably, features learned from unsupervised methods, specifically latent Dirichlet allocation, perform almost as well as with as those from supervised methods. The unsupervised clusters learned in this task shows promise of finer grain inference of social nature of telephone conversations. PMID:22754884

  11. Opportunities for Learning-Based Conversations in High School Mathematics

    ERIC Educational Resources Information Center

    McFeetors, Janelle

    2015-01-01

    Conversations as moments for interpersonal and intimate turning round of ideas for the purpose of growth are well-defined within curriculum inquiry. Interactions among grade 12 students in this study demonstrate the possibility of learning to learn mathematics through conversation. Attending to opportunities for learning-based conversations,…

  12. Opportunities for Learning-Based Conversations in High School Mathematics

    ERIC Educational Resources Information Center

    McFeetors, Janelle

    2015-01-01

    Conversations as moments for interpersonal and intimate turning round of ideas for the purpose of growth are well-defined within curriculum inquiry. Interactions among grade 12 students in this study demonstrate the possibility of learning to learn mathematics through conversation. Attending to opportunities for learning-based conversations,…

  13. Conversion feasibility studies for the Grenoble high flux reactor

    SciTech Connect

    Mo, S.C.; Matos, J.E.

    1989-01-01

    Feasibility studies for conversion of the High Flux Reactor (RHF) at Grenoble France have been performed at the Argonne National Laboratory in cooperation with the Institut Laue-Langevin (ILL). The uranium densities required for conversion of the RHF to reduced enrichment fuels were computed to be 7.9 g/cm{sup 3} with 20% enrichment, 4.8 g/cm{sup 3} with 29% enrichment, and 2.8 g/cm{sup 3} with 45% enrichment. Thermal flux reductions at the peak in the heavy water reflector were computed to be 3% with 45% enriched fuel and 7% with 20% enriched fuel. In each case, the reactor's 44 day cycle length was preserved and no changes were made in the fuel element geometry. If the cladding thickness could be reduced from 0.38 mm to 0.30 mm, the required uranium density with 20% enrichment would be about 6.0 g/cm{sup 3} and the thermal flux reduction at the peak in the heavy water reflector would be about 7%. Significantly higher uranium densities are required in the RHF than in heavy water reactors with more conventional designs because the neutron spectrum is much harder in the RHF. Reduced enrichment fuels with the uranium densities required for use in the RHF are either not available or are not licensable at the present time. 6 refs., 6 figs., 3 tabs.

  14. Selective conversion of bio-oil to light olefins: controlling catalytic cracking for maximum olefins.

    PubMed

    Gong, Feiyan; Yang, Zhi; Hong, Chenggui; Huang, Weiwei; Ning, Shen; Zhang, Zhaoxia; Xu, Yong; Li, Quanxin

    2011-10-01

    Light olefins are the basic building blocks for the petrochemical industry. In this work, selective production of light olefins from catalytic cracking of bio-oil was performed by using the La/HZSM-5 catalyst. With a nearly complete conversion of bio-oil, the maximum yield reached 0.28±0.02 kg olefins/(kg bio-oil), which was close to that from methanol. Addition of La into zeolite efficiently changed the total acid amount of HZSM-5, especially the acid distribution among the strong, medium and weak acid sites. A moderate increase of the number of the medium acid sites effectively enhanced the olefins selectivity and improved the catalyst stability. The comparison between the catalytic cracking and pyrolysis of bio-oil was studied. The mechanism of the conversion of bio-oil to light olefins was also discussed.

  15. Riverbed methanotrophy sustained by high carbon conversion efficiency

    PubMed Central

    Trimmer, Mark; Shelley, Felicity C; Purdy, Kevin J; Maanoja, Susanna T; Chronopoulou, Panagiota-Myrsini; Grey, Jonathan

    2015-01-01

    Our understanding of the role of freshwaters in the global carbon cycle is being revised, but there is still a lack of data, especially for the cycling of methane, in rivers and streams. Unravelling the role of methanotrophy is key to determining the fate of methane in rivers. Here we focus on the carbon conversion efficiency (CCE) of methanotrophy, that is, how much organic carbon is produced per mole of CH4 oxidised, and how this is influenced by variation in methanotroph communities. First, we show that the CCE of riverbed methanotrophs is consistently high (~50%) across a wide range of methane concentrations (~10–7000 nM) and despite a 10-fold span in the rate of methane oxidation. Then, we show that this high conversion efficiency is largely conserved (50%± confidence interval 44–56%) across pronounced variation in the key functional gene (70 operational taxonomic units (OTUs)), particulate methane monooxygenase (pmoA), and marked shifts in the abundance of Type I and Type II methanotrophs in eight replicate chalk streams. These data may suggest a degree of functional redundancy within the variable methanotroph community inhabiting these streams and that some of the variation in pmoA may reflect a suite of enzymes of different methane affinities which enables such a large range of methane concentrations to be oxidised. The latter, coupled to their high CCE, enables the methanotrophs to sustain net production throughout the year, regardless of the marked temporal and spatial changes that occur in methane. PMID:26057842

  16. Mode-Selective Photon Counting Via Quantum Frequency Conversion Using Spectrally-Engineered Pump Pulses

    NASA Astrophysics Data System (ADS)

    Manurkar, Paritosh

    Most of the existing protocols for quantum communication operate in a two-dimensional Hilbert space where their manipulation and measurement have been routinely investigated. Moving to higher-dimensional Hilbert spaces is desirable because of advantages in terms of longer distance communication capabilities, higher channel capacity and better information security. We can exploit the spatio-temporal degrees of freedom for the quantum optical signals to provide the higher-dimensional signals. But this necessitates the need for measurement and manipulation of multidimensional quantum states. To that end, there have been significant theoretical studies based on quantum frequency conversion (QFC) in recent years even though the experimental progress has been limited. QFC is a process that allows preservation of the quantum information while changing the frequency of the input quantum state. It has deservedly garnered a lot of attention because it serves as the connecting bridge between the communications band (C-band near 1550 nm) where the fiber-optic infrastructure is already established and the visible spectrum where high efficiency single-photon detectors and optical memories have been demonstrated. In this experimental work, we demonstrate mode-selective frequency conversion as a means to measure and manipulate photonic signals occupying d -dimensional Hilbert spaces where d=2 and 4. In the d=2 case, we demonstrate mode contrast between two temporal modes (TMs) which serves as the proof-of-concept demonstration. In the d=4 version, we employ six different TMs for our detailed experimental study. These TMs also include superposition modes which are a crucial component in many quantum key distribution protocols. Our method is based on producing pump pulses which allow us to upconvert the TM of interest while ideally preserving the other modes. We use MATLAB simulations to determine the pump pulse shapes which are subsequently produced by controlling the amplitude and

  17. High temperature size selective membranes

    SciTech Connect

    Yates, S.F.; Swamikannu, A.X.

    1993-09-01

    The high temperature membrane, capable of operation above 550{degree}C, is designed to be a composite membrane composed of a thin layer of a size selective membrane supported by a microporous ceramic support. The kinetic diameters of H{sub 2} and CO{sub 2} are 2.96 {Angstrom} and 4.00 {Angstrom}. The thin layer will be made from CMS whose pore size will be controlled to be less than 4 {Angstrom}. The membrane will be truly size selective and be impermeable to carbon dioxide. The membrane will have higher selectivity than membranes which operate on Knudsen diffusion mechanism. The ceramic support will be fabricated from Allied Signal`s proprietary Blackglas{trademark} resin. The ceramic material, noted for its high thermal and oxidative resistance, has a coefficient of thermal expansion which matches closely that of CMS. The close match will insure mechanical integrity when the membrane is subjected to thermal cycles. The CMS layer will be produced by controlled pyrolysis of polymeric precursors. Pore size will be suitably modified by post-treatments to the carbon. The composite membrane will be tested for its permeation properties at 550{degree}C or higher. Thermal, mechanical and chemical stability of the membrane will be assessed. We have produced several samples of CMS from polymeric precursors. We have initiated work also on the preparation of microporous supports from Blackglas{trademark} resin. We have completed the design of the high temperature membrane pilot plant. The membrane cell was fabricated out of two kinds of stainless steel. The inner parts are made of SS 316 and the outer ring made of SS 420. The greater thermal expansion of the SS 316 will help obtain a leak free seal at the operating temperatures.

  18. Catalytic conversion reactions in nanoporous systems with concentration-dependent selectivity: Statistical mechanical modeling

    NASA Astrophysics Data System (ADS)

    García, Andrés; Wang, Jing; Windus, Theresa L.; Sadow, Aaron D.; Evans, James W.

    2016-05-01

    Statistical mechanical modeling is developed to describe a catalytic conversion reaction A →Bc or Bt with concentration-dependent selectivity of the products, Bc or Bt, where reaction occurs inside catalytic particles traversed by narrow linear nanopores. The associated restricted diffusive transport, which in the extreme case is described by single-file diffusion, naturally induces strong concentration gradients. Furthermore, by comparing kinetic Monte Carlo simulation results with analytic treatments, selectivity is shown to be impacted by strong spatial correlations induced by restricted diffusivity in the presence of reaction and also by a subtle clustering of reactants, A .

  19. Catalytic conversion reactions in nanoporous systems with concentration-dependent selectivity: Statistical mechanical modeling

    DOE PAGES

    Garcia, Andres; Wang, Jing; Windus, Theresa L.; ...

    2016-05-20

    Statistical mechanical modeling is developed to describe a catalytic conversion reaction A → Bc or Bt with concentration-dependent selectivity of the products, Bc or Bt, where reaction occurs inside catalytic particles traversed by narrow linear nanopores. The associated restricted diffusive transport, which in the extreme case is described by single-file diffusion, naturally induces strong concentration gradients. Hence, by comparing kinetic Monte Carlo simulation results with analytic treatments, selectivity is shown to be impacted by strong spatial correlations induced by restricted diffusivity in the presence of reaction and also by a subtle clustering of reactants, A.

  20. Surface modification of ZSM-5 zeolite: effect of cation on selective conversion of biomass-derived oil

    NASA Astrophysics Data System (ADS)

    Widayatno, W. B.

    2017-04-01

    This paper reports the surface modification of high silica ZSM-5 zeolite, particularly emphasizing the effect of cation type on selective conversion of biomass-derived oil. XRD spectra of the NaOH-treated HZSM-5 showed notable crystallinity decrease at specific crystal plane orientation. The N2-physisorption tests confirmed mesoporosity evolution as NaOH concentration was increased. NH3-desorption tests revealed a significant change on surface acidity which involved realumination and cation replacement processes. The utilization of untreated HZSM-5 as well as hierarchical NaZSM-5 for catalytic conversion of bio-oil showed the effect of cation type and mesoporosity on chemicals distribution. The untreated HZSM-5 showed high selectivity to aromatics, which degraded gradually due to deactivation and poisoning of the acid sites. Meanwhile, hierarchical NaZSM-5 showed high selectivity to phenolic compound, which became more stable for 0.4M NaOH-treated zeolite (Na04). The current findings provide an additional insight on the potentials of NaZSM-5 for bio-oil valorization.

  1. Integrated Biomass Gasification with Catalytic Partial Oxidation for Selective Tar Conversion

    SciTech Connect

    Zhang, Lingzhi; Wei, Wei; Manke, Jeff; Vazquez, Arturo; Thompson, Jeff; Thompson, Mark

    2011-05-28

    requirement for commercial deployment of biomass-based power/heat co-generation and biofuels production. There are several commonly used syngas clean-up technologies: (1) Syngas cooling and water scrubbing has been commercially proven but efficiency is low and it is only effective at small scales. This route is accompanied with troublesome wastewater treatment. (2) The tar filtration method requires frequent filter replacement and solid residue treatment, leading to high operation and capital costs. (3) Thermal destruction typically operates at temperatures higher than 1000oC. It has slow kinetics and potential soot formation issues. The system is expensive and materials are not reliable at high temperatures. (4) In-bed cracking catalysts show rapid deactivation, with durability to be demonstrated. (5) External catalytic cracking or steam reforming has low thermal efficiency and is faced with problematic catalyst coking. Under this program, catalytic partial oxidation (CPO) is being evaluated for syngas tar clean-up in biomass gasification. The CPO reaction is exothermic, implying that no external heat is needed and the system is of high thermal efficiency. CPO is capable of processing large gas volume, indicating a very compact catalyst bed and a low reactor cost. Instead of traditional physical removal of tar, the CPO concept converts tar into useful light gases (eg. CO, H2, CH4). This eliminates waste treatment and disposal requirements. All those advantages make the CPO catalytic tar conversion system a viable solution for biomass gasification downstream gas clean-up. This program was conducted from October 1 2008 to February 28 2011 and divided into five major tasks. - Task A: Perform conceptual design and conduct preliminary system and economic analysis (Q1 2009 ~ Q2 2009) - Task B: Biomass gasification tests, product characterization, and CPO tar conversion catalyst preparation. This task will be conducted after completing process design and system economics analysis

  2. Elective delayed midgut reduction-No anesthesia for gastroschisis: Selection and conversion criteria.

    PubMed

    Bianchi, A; Dickson, A P; Alizai, N K

    2002-09-01

    In 1998 Bianchi and Dickson published their proposal for elective delayed midgut reduction without anaesthesia (EDMR-No GA). The study has been prospectively extended to develop "selection and conversion criteria" to ensure safe application of the technique. In a prospective study from 1993 to date, EDMR-No GA was considered as first-line postnatal management in 35 children. The protocol and technique were those described by Bianchi and Dickson in 1998. EDMR-No GA was completed successfully in 25 children, of whom, 23 are normal with an aesthetic, scarless abdomen. Two children had bowel necrosis and died of short bowel state. A trial EDMR-No GA was converted to a staged silo reduction in 2 children who are both alive and well. EDMR-No GA was considered contraindicated in 8. Five had an elective, staged silo reduction, 2 had EDMR under anesthesia, and one 27-week-gestation baby died of severe hypothermia and acidosis before any procedure. No single technique is applicable in all circumstances, and "selection and conversion criteria" are relevant to safe EDMR-No GA. These include poor general condition, significant vital organ anomaly, bowel-to-abdomen disproportion and "at risk" bowel circulation. The development of distress and progressive metabolic acidosis during and after EDMR-No GA, are indications for urgent conversion to avoid serious bowel injury. Experience with EDMR-No GA hones the surgeon's sensitivity in assessing abdominal. Copyright 2002, Elsevier Science (USA). All rights reserved.

  3. Nanolaminated Permalloy Core for High-Flux, High-Frequency Ultracompact Power Conversion

    SciTech Connect

    Kim, J; Kim, M; Galle, P; Herrault, F; Shafer, R; Park, JY; Allen, MG

    2013-09-01

    Metallic magnetic materials have desirable magnetic properties, including high permeability, and high saturation flux density, when compared with their ferrite counterparts. However, eddy-current losses preclude their use in many switching converter applications, due to the challenge of simultaneously achieving sufficiently thin laminations such that eddy currents are suppressed (e.g., 500 nm-1 mu m for megahertz frequencies), while simultaneously achieving overall core thicknesses such that substantial power can be handled. A CMOS-compatible fabrication process based on robot-assisted sequential electrodeposition followed by selective chemical etching has been developed for the realization of a core of substantial overall thickness (tens to hundreds of micrometers) comprised of multiple, stacked permalloy (Ni80Fe20) nanolaminations. Tests of toroidal inductors with nanolaminated cores showed negligible eddy-current loss relative to total core loss even at a peak flux density of 0.5 T in the megahertz frequency range. To illustrate the use of these cores, a buck power converter topology is implemented with switching frequencies of 1-2 MHz. Power conversion efficiency greater than 85% with peak operating flux density of 0.3-0.5 T in the core and converter output power level exceeding 5 W was achieved.

  4. High Average Power Raman Conversion in Diamond: ’Eyesafe’ Output and Fiber Laser Conversion

    DTIC Science & Technology

    2015-06-19

    power. The efficiencies and brightness achieved are found to be higher than expected by current theories for thermal effects in diamond. The project...power can be scaled before thermal effects become evident. The mechanism for heat deposition and its spatial dependence are found to be poorly...the non- thermal regime. Demonstration of efficient (up 60%) Raman conversion of cw fiber lasers of power up to 630 W. Several further findings are

  5. Low-temperature thermochemical conversion of high-moisture biomass feedstocks

    SciTech Connect

    Butner, R.S.; Sealock, L.J. Jr.; Elliott, D.C.

    1985-11-01

    Pacific Northwest Laboratory is carrying out a research project to investigate the thermochemical conversion of high-moisture biomass feedstocks to methane, hydrogen, and liquids. Experimental results obtained in FY 1985 indicate that good yields of methane-rich gas (exceeding 40% methane) can be produced. The reaction system utilizes low tempreatures (400 to 450/sup 0/C), high pressures, and a nickel/alkali carbonate catalyst mixture to effect the gasification of biomass slurries containing up to 95% water. Carbon conversions after 15 minutes have exceeded 90%. Methane yields in excess of 6 scf/dry ash-free pound of biomass have been obtained. Most of the feedstocks selected for investigation are not conventionally used in thermochemical conversion. Feedstocks which have been used to data include napier grass, sorghum stover, sunflower stalks, water hyacinths, and macrocystis kelp. Waste biomass from the food and beverage industries has also been used, as has the unconverted residue from an anaerobic digestor. In addition to gasification performance data obtained for each of these feedstocks, elemental analyses, ash contents, and moisture contents of the raw feedstocks were determined. 5 refs., 8 figs., 2 tabs.

  6. Selective disclosure in a first conversation about a family death in James Agee's novel A Death in the Family.

    PubMed

    Rober, Peter; Rosenblatt, Paul C

    2013-02-01

    The first conversation of a family about a family death is a neglected but potentially important topic. In a first conversation in James Agee's (1957/ 2006) novel A Death in the Family, the member who knows the most about the accidental death of another member discloses information selectively. The first conversation in Agee's novel suggests that communication and caring in the first family conversation about a death is attuned to family member emotions, particularly those of the family member considered most vulnerable, and that the aim is not a shared narrative that is true, but one that people can live with.

  7. Compact, High-Power, Low-Cost 295 nm DUV Laser by Harmonic Conversion of High Power VECSELs

    DTIC Science & Technology

    2011-05-10

    REPORT Compact, High-Power, Low-Cost 295 nm DUV Laser by Harmonic Conversion of High Power VECSELs 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We have...harmonic Conversion, high power, VECSEL Mahmoud Fallahi University of Arizona Sponsored Project Services PO Box 3308 Tucson, AZ 85722 -3308 REPORT...8/98) Prescribed by ANSI Std. Z39.18 - 14-Jun-2010 Compact, High-Power, Low-Cost 295 nm DUV Laser by Harmonic Conversion of High Power VECSELs

  8. Catalytic conversion reactions in nanoporous systems with concentration-dependent selectivity: Statistical mechanical modeling

    SciTech Connect

    Garcia, Andres; Wang, Jing; Windus, Theresa L.; Sadow, Aaron D.; Evans, James W.

    2016-05-20

    Statistical mechanical modeling is developed to describe a catalytic conversion reaction A → Bc or Bt with concentration-dependent selectivity of the products, Bc or Bt, where reaction occurs inside catalytic particles traversed by narrow linear nanopores. The associated restricted diffusive transport, which in the extreme case is described by single-file diffusion, naturally induces strong concentration gradients. Hence, by comparing kinetic Monte Carlo simulation results with analytic treatments, selectivity is shown to be impacted by strong spatial correlations induced by restricted diffusivity in the presence of reaction and also by a subtle clustering of reactants, A.

  9. Selective CO2 conversion to formate conjugated with H2O oxidation utilizing semiconductor/complex hybrid photocatalysts.

    PubMed

    Sato, Shunsuke; Arai, Takeo; Morikawa, Takeshi; Uemura, Keiko; Suzuki, Tomiko M; Tanaka, Hiromitsu; Kajino, Tsutomu

    2011-10-05

    Photoelectrochemical reduction of CO(2) to HCOO(-) (formate) over p-type InP/Ru complex polymer hybrid photocatalyst was highly enhanced by introducing an anchoring complex into the polymer. By functionally combining the hybrid photocatalyst with TiO(2) for water oxidation, selective photoreduction of CO(2) to HCOO(-) was achieved in aqueous media, in which H(2)O was used as both an electron donor and a proton source. The so-called Z-scheme (or two-step photoexcitation) system operated with no external electrical bias. The selectivity for HCOO(-) production was >70%, and the conversion efficiency of solar energy to chemical energy was 0.03-0.04%.

  10. Carbon Dioxide Conversion to Methanol over Size-Selected Cu 4 Clusters at Low Pressures

    DOE PAGES

    Liu, Cong; Yang, Bing; Tyo, Eric; ...

    2015-06-26

    In order to utilize the captured CO2, the activation of CO2 and its hydrogenation to methanol are of much interest . We investigate the use of size-selected Cu-4 clusters supported on Al2O3 thin films for CO2 reduction in the presence of hydrogen. The catalytic activity was measured under near-atmospheric reaction conditions with a low CO2 partial pressure, and the oxidation state of the clusters was investigated by in situ grazing incidence X-ray absorption spectroscopy. The results indicate that size-selected Cu-4 clusters are the most active low-pressure catalyst for catalytic CO2 conversion to CH3OH. Density functional theory calculations reveal that Cu-4more » clusters have a low activation barrier for conversion of CO2 to CH3OH. Our study suggests that small Cu clusters may be excellent and efficient catalysts for the recycling of released CO2.« less

  11. Conversion of organic wastes to unleaded, high-octane gasoline

    SciTech Connect

    Diebold, J.P.; Benham, C.B.; Smith, G.D.

    1984-01-01

    This project has demonstrated the marriage of two diverse technologies previously considered to be unrelated--the pyrolysis of organic wastes and the low-pressure polymerization of low-molecular-weight hydrocarbons to form polymer gasoline. This program comprised the development of a multistep chemical process to convert solid organic materials into a liquid hydrocarbon product consisting primarily of high-octane gasoline. This process selectively pyrolyzes organic wastes to form gases rich in reactive hydrocarbons such as ethylene and propylene. The pyrolysis gases are compressed and purified to result in three gaseous streams: carbon dioxide; by-product fuel gases (hydrogen, methane, and carbon monoxide); and reactive hydrocarbons. This last stream is further compressed and sent to the polymerization reactor where high-octane gasoline is formed.

  12. Thermoelectric Energy Conversion Technology for High-Altitude Airships

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Elliott, James R.; King, Glen C.; Park, Yeonjoon; Kim, Jae-Woo; Chu, Sang-Hyon

    2011-01-01

    The High Altitude Airship (HAA) has various application potential and mission scenarios that require onboard energy harvesting and power distribution systems. The power technology for HAA maneuverability and mission-oriented applications must come from its surroundings, e.g. solar power. The energy harvesting system considered for HAA is based on the advanced thermoelectric (ATE) materials being developed at NASA Langley Research Center. The materials selected for ATE are silicon germanium (SiGe) and bismuth telluride (Bi2Te3), in multiple layers. The layered structure of the advanced TE materials is specifically engineered to provide maximum efficiency for the corresponding range of operational temperatures. For three layers of the advanced TE materials that operate at high, medium, and low temperatures, correspondingly in a tandem mode, the cascaded efficiency is estimated to be greater than 60 percent.

  13. High-temperature corrosion: Issues in alloy selection

    NASA Astrophysics Data System (ADS)

    Lai, George Y.

    1991-11-01

    This article examines the modes of high-temperature corrosion that are often responsible for equipment failures in a variety of industries, including aerospace and gas turbines; heat treating; mineral and metallurgical processing; chemical processing; refining and petrochemical processing; ceramic, electronic, and glass manufacturing; automotive; pulp and paper; waste incineration; and power generation and energy conversion. Corrosion data related to each corrosion mode are reviewed to provide readers with a brief materials selection guide.

  14. Analysis of proinsulin and its conversion products by reversed-phase high-performance liquid chromatography.

    PubMed

    Linde, S; Welinder, B S; Nielsen, J H

    1993-05-05

    Proinsulin is synthesized in the beta-cells of the endocrine pancreas, one of the four cell types found in the islets of Langerhans. Specific enzymatic cleavage of proinsulin results in the formation of equimolar amounts of insulin and C-peptide, via several intermediate split-proinsulin forms. Most mammals produce a single insulin, but in rodents two non-allelic insulin genes are expressed. There is an inverse ratio between the two insulins in rats and mice, the reason for this being unknown. It has been suggested that differences in transcription, translation (biosynthesis) and/or posttranslational processes (enzymatic conversion, intracellular degradation) could be possible explanations. Elevated amounts of proinsulin-immunoreactive material (PIM) have been described to occur in various conditions/diseases, suggesting alterations in beta-cell function, but the composition of the secreted PIM (intact proinsulin or its intermediates) has been incompletely determined. Studies of the biosynthesis of proinsulins and their conversion with the purpose of revealing some of these points depend on accessible reversed-phase high-performance liquid chromatographic (RP-HPLC) analyses capable of separating all the relevant, closely related polypeptides involved. This review will deal with the optimization of the RP-HPLC separations as well as sample preparation and recovery. Applications of the selected methods in the study of proinsulin biosynthesis and its conversion will also be presented.

  15. The Impact of Selection, Gene Conversion, and Biased Sampling on the Assessment of Microbial Demography.

    PubMed

    Lapierre, Marguerite; Blin, Camille; Lambert, Amaury; Achaz, Guillaume; Rocha, Eduardo P C

    2016-07-01

    Recent studies have linked demographic changes and epidemiological patterns in bacterial populations using coalescent-based approaches. We identified 26 studies using skyline plots and found that 21 inferred overall population expansion. This surprising result led us to analyze the impact of natural selection, recombination (gene conversion), and sampling biases on demographic inference using skyline plots and site frequency spectra (SFS). Forward simulations based on biologically relevant parameters from Escherichia coli populations showed that theoretical arguments on the detrimental impact of recombination and especially natural selection on the reconstructed genealogies cannot be ignored in practice. In fact, both processes systematically lead to spurious interpretations of population expansion in skyline plots (and in SFS for selection). Weak purifying selection, and especially positive selection, had important effects on skyline plots, showing patterns akin to those of population expansions. State-of-the-art techniques to remove recombination further amplified these biases. We simulated three common sampling biases in microbiological research: uniform, clustered, and mixed sampling. Alone, or together with recombination and selection, they further mislead demographic inferences producing almost any possible skyline shape or SFS. Interestingly, sampling sub-populations also affected skyline plots and SFS, because the coalescent rates of populations and their sub-populations had different distributions. This study suggests that extreme caution is needed to infer demographic changes solely based on reconstructed genealogies. We suggest that the development of novel sampling strategies and the joint analyzes of diverse population genetic methods are strictly necessary to estimate demographic changes in populations where selection, recombination, and biased sampling are present. © The Author 2016. Published by Oxford University Press on behalf of the Society for

  16. The Impact of Selection, Gene Conversion, and Biased Sampling on the Assessment of Microbial Demography

    PubMed Central

    Lapierre, Marguerite; Blin, Camille; Lambert, Amaury; Achaz, Guillaume; Rocha, Eduardo P. C.

    2016-01-01

    Recent studies have linked demographic changes and epidemiological patterns in bacterial populations using coalescent-based approaches. We identified 26 studies using skyline plots and found that 21 inferred overall population expansion. This surprising result led us to analyze the impact of natural selection, recombination (gene conversion), and sampling biases on demographic inference using skyline plots and site frequency spectra (SFS). Forward simulations based on biologically relevant parameters from Escherichia coli populations showed that theoretical arguments on the detrimental impact of recombination and especially natural selection on the reconstructed genealogies cannot be ignored in practice. In fact, both processes systematically lead to spurious interpretations of population expansion in skyline plots (and in SFS for selection). Weak purifying selection, and especially positive selection, had important effects on skyline plots, showing patterns akin to those of population expansions. State-of-the-art techniques to remove recombination further amplified these biases. We simulated three common sampling biases in microbiological research: uniform, clustered, and mixed sampling. Alone, or together with recombination and selection, they further mislead demographic inferences producing almost any possible skyline shape or SFS. Interestingly, sampling sub-populations also affected skyline plots and SFS, because the coalescent rates of populations and their sub-populations had different distributions. This study suggests that extreme caution is needed to infer demographic changes solely based on reconstructed genealogies. We suggest that the development of novel sampling strategies and the joint analyzes of diverse population genetic methods are strictly necessary to estimate demographic changes in populations where selection, recombination, and biased sampling are present. PMID:26931140

  17. Overview of novel photovoltaic conversion techniques at high intensity levels

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.

    1978-01-01

    The paper describes several photovoltaic devices currently under development that can operate under light intensities considerably higher than can silicon solar cells. The technologies discussed include GaAs heteroface solar cells, multi-color systems, thermophotovoltaics, and laser energy conversion. Array costs for the GaAs and multi-color elements are estimated.

  18. Overview of novel photovoltaic conversion techniques at high intensity levels

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.

    1978-01-01

    The paper describes several photovoltaic devices currently under development that can operate under light intensities considerably higher than can silicon solar cells. The technologies discussed include GaAs heteroface solar cells, multi-color systems, thermophotovoltaics, and laser energy conversion. Array costs for the GaAs and multi-color elements are estimated.

  19. Efficiency of Drude mirror-type selective transparent filters for solar thermal conversion.

    PubMed

    Yoshida, S

    1978-01-01

    The efficiency of the solar collector consisting of a selective absorber and a selective transparent filter is derived for comparing and evaluating the collectors. The efficiency of Drude mirror type selective transparent filters is calculated in cases of a blackbody absorber and the Al(2)O(3)-Mo-Al(2)O(3)-Mo highly selective absorber. As Drude mirrors, Sn-doped In(2)O(3) films were formed on Pyrex glass plates by rf sputtering, and the dependence of the efficiencies on the operating conditions of the collector, including solar concentration and temperature of the absorber, is discussed.

  20. Highly efficient frequency conversion with bandwidth compression of quantum light

    NASA Astrophysics Data System (ADS)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  1. Highly efficient frequency conversion with bandwidth compression of quantum light

    PubMed Central

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks. PMID:28134242

  2. Conversion of microwave pyrolysed ASR's char using high temperature agents.

    PubMed

    Donaj, Pawel; Blasiak, Wlodzimierz; Yang, Weihong; Forsgren, Christer

    2011-01-15

    Pyrolysis enables to recover metals and organic feedstock from waste conglomerates such as: automotive shredder residue (ASR). ASR as well as its pyrolysis solid products, is a morphologically and chemically varied mixture, containing mineral materials, including hazardous heavy metals. The aim of the work is to generate fundamental knowledge on the conversion of the organic residues of the solid products after ASR's microwave pyrolysis, treated at various temperatures and with two different types of gasifying agent: pure steam or 3% (v/v) of oxygen. The research is conducted using a lab-scale, plug-flow gasifier, with an integrated scale for analysing mass loss changes over time of experiment, serving as macro TG at 950, 850 and 760 °C. The reaction rate of char decomposition was investigated, based on carbon conversion during gasification and pyrolysis stage. It was found in both fractions that char conversion rate decreases with the rise of external gas temperature, regardless of the gasifying agent. No significant differences between the reaction rates undergoing with steam and oxygen for char decomposition has been observed. This abnormal char behaviour might have been caused by the inhibiting effects of ash, especially alkali metals on char activity or due to deformation of char structure during microwave heating. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Promoted Iron Nanocrystals Obtained via Ligand Exchange as Active and Selective Catalysts for Synthesis Gas Conversion.

    PubMed

    Casavola, Marianna; Xie, Jingxiu; Meeldijk, Johannes D; Krans, Nynke A; Goryachev, Andrey; Hofmann, Jan P; Dugulan, A Iulian; de Jong, Krijn P

    2017-08-04

    Colloidal synthesis routes have been recently used to fabricate heterogeneous catalysts with more controllable and homogeneous properties. Herein a method was developed to modify the surface composition of colloidal nanocrystal catalysts and to purposely introduce specific atoms via ligands and change the catalyst reactivity. Organic ligands adsorbed on the surface of iron oxide catalysts were exchanged with inorganic species such as Na2S, not only to provide an active surface but also to introduce controlled amounts of Na and S acting as promoters for the catalytic process. The catalyst composition was optimized for the Fischer-Tropsch direct conversion of synthesis gas into lower olefins. At industrially relevant conditions, these nanocrystal-based catalysts with controlled composition were more active, selective, and stable than catalysts with similar composition but synthesized using conventional methods, possibly due to their homogeneity of properties and synergic interaction of iron and promoters.

  4. Promoted Iron Nanocrystals Obtained via Ligand Exchange as Active and Selective Catalysts for Synthesis Gas Conversion

    PubMed Central

    2017-01-01

    Colloidal synthesis routes have been recently used to fabricate heterogeneous catalysts with more controllable and homogeneous properties. Herein a method was developed to modify the surface composition of colloidal nanocrystal catalysts and to purposely introduce specific atoms via ligands and change the catalyst reactivity. Organic ligands adsorbed on the surface of iron oxide catalysts were exchanged with inorganic species such as Na2S, not only to provide an active surface but also to introduce controlled amounts of Na and S acting as promoters for the catalytic process. The catalyst composition was optimized for the Fischer–Tropsch direct conversion of synthesis gas into lower olefins. At industrially relevant conditions, these nanocrystal-based catalysts with controlled composition were more active, selective, and stable than catalysts with similar composition but synthesized using conventional methods, possibly due to their homogeneity of properties and synergic interaction of iron and promoters. PMID:28824820

  5. Gene conversion and purifying selection shape nucleotide variation in gibbon L/M opsin genes

    PubMed Central

    2011-01-01

    role of gene conversion between the L and M opsin genes and for the purifying selection against such homogenization in the central exons to maintain the spectral difference between L and M opsins in non-human catarrhines. PMID:22017819

  6. Gene conversion and purifying selection shape nucleotide variation in gibbon L/M opsin genes.

    PubMed

    Hiwatashi, Tomohide; Mikami, Akichika; Katsumura, Takafumi; Suryobroto, Bambang; Perwitasari-Farajallah, Dyah; Malaivijitnond, Suchinda; Siriaroonrat, Boripat; Oota, Hiroki; Goto, Shunji; Kawamura, Shoji

    2011-10-22

    Routine trichromatic color vision is a characteristic feature of catarrhines (humans, apes and Old World monkeys). This is enabled by L and M opsin genes arrayed on the X chromosome and an autosomal S opsin gene. In non-human catarrhines, genetic variation affecting the color vision phenotype is reported to be absent or rare in both L and M opsin genes, despite the suggestion that gene conversion has homogenized the two genes. However, nucleotide variation of both introns and exons among catarrhines has only been examined in detail for the L opsin gene of humans and chimpanzees. In the present study, we examined the nucleotide variation of gibbon (Catarrhini, Hylobatidae) L and M opsin genes. Specifically, we focused on the 3.6~3.9-kb region that encompasses the centrally located exon 3 through exon 5, which encode the amino acid sites functional for the spectral tuning of the genes. Among 152 individuals representing three genera (Hylobates, Nomascus and Symphalangus), all had both L and M opsin genes and no L/M hybrid genes. Among 94 individuals subjected to the detailed DNA sequencing, the nucleotide divergence between L and M opsin genes in the exons was significantly higher than the divergence in introns in each species. The ratio of the inter-LM divergence to the intra-L/M polymorphism was significantly lower in the introns than that in synonymous sites. When we reconstructed the phylogenetic tree using the exon sequences, the L/M gene duplication was placed in the common ancestor of catarrhines, whereas when intron sequences were used, the gene duplications appeared multiple times in different species. Using the GENECONV program, we also detected that tracts of gene conversions between L and M opsin genes occurred mostly within the intron regions. These results indicate the historical accumulation of gene conversions between L and M opsin genes in the introns in gibbons. Our study provides further support for the homogenizing role of gene conversion between

  7. Performance evaluation of selective mode conversion based on phase plates for a 10-mode fiber.

    PubMed

    Igarashi, Koji; Souma, Daiki; Tsuritani, Takehiro; Morita, Itsuro

    2014-08-25

    We numerically and experimentally evaluate the performance of higher-order mode conversion based on phase plates for 10-mode fibers (10MFs). The phase plates have the phase jump of π between multiple planes, which match the phase patterns of linearly polarized (LP) modes of 10MF. First, we numerically investigate the effects of the fabrication errors such as the phase-difference error and the slope in the phase jump of the phase plate. The simulation results for the mode conversion to LP11 indicate that such errors make the spatial pattern of the converted beam asymmetric. In order to maintain the symmetric pattern, the phase-difference error is required to be less than ± 2%, and the ratio of the slope width to the input beam waist should be suppressed to be less than 0.05. Next, we calculate the coupling power efficiencies of the excitation of LP modes in 10MF when the converted beams after the phase plate are launched into 10MF using a lens. As the calculation results, highly accurate adjustment of the input beam waist is required to suppress the crosstalk due to coupling of undesirable LP modes by less than -20 dB. For mode excitation of LP11 or LP12, crosstalk of more than -20 dB is not avoidable even if the input beam waist is carefully adjusted. In contrast, the crosstalk for the mode excitation of LP21 or LP31 is easily suppressed to be less than -20 dB without careful adjustment of the input beam waist. These results suggest that phase plates are not applicable to mode conversion to LP11 and LP12 in 10MF while they are suitable for conversion to LP02, LP21 and LP31. Finally, we experimentally demonstrate conversion from LP01 to LP21 and LP31 modes in 10MF using phase plates. We obtain nearly ideal LP21 and LP31 modes with the small crosstalk due to the coupling of the other undesirable LP modes.

  8. Strain selection, biomass to biofuel conversion, and resource colocation have strong impacts on the economic performance of algae cultivation sites

    SciTech Connect

    Venteris, Erik R.; Wigmosta, Mark S.; Coleman, Andre M.; Skaggs, Richard

    2014-09-16

    Decisions involving strain selection, biomass to biofuel technology, and the location of cultivation facilities can strongly influence the economic viability of an algae-based biofuel enterprise. In this contribution we summarize our past results in a new analysis to explore the relative economic impact of these design choices. We present strain-specific growth model results from two saline strains (Nannocloropsis salina, Arthrospira sp.), a fresh to brackish strain (Chlorella sp., DOE strain 1412), and a freshwater strain of the order Sphaeropleales. Biomass to biofuel conversion is compared between lipid extraction (LE) and hydrothermal liquefaction (HTL) technologies. National-scale models of water, CO2 (as flue gas), land acquisition, site leveling, construction of connecting roads, and transport of HTL oil to existing refineries are used in conjunction with estimates of fuel value (from HTL) to prioritize and select from 88,692 unit farms (UF, 405 ha in pond area), a number sufficient to produce 136E+9 L yr-1 of renewable diesel (36 billion gallons yr-1, BGY). Strain selection and choice of conversion technology have large economic impacts, with differences between combinations of strains and biomass to biofuel technologies being up to $10 million dollars yr-1 UF-1. Results based on the most productive species, HTL-based fuel conversion, and resource costs show that the economic potential between geographic locations within the selection can differ by up to $4 million yr-1 UF-1, with 2.0 BGY of production possible from the most cost-effective sites. The local spatial variability in site rank is extreme, with very high and low rank sites within 10s of km of each other. Colocation with flue gas sources has a strong influence on site rank, but the most costly resource component varies from site to site. The highest rank sites are located predominantly in Florida and Texas, but most states south of 37°N latitude contain promising locations. Keywords: algae

  9. NASA-OAST/JPL high efficiency thermionic conversion studies. [nuclear electric propulsion

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Efforts were made to develop a thermionic energy conversion TEC technology appropriate for nuclear electric propulsion missions. This space TEC effort was complementary to the terrestrial TEC studies sponsored by the Department of Energy which had the goal of topping fossil fuel power plants. Thermionic energy conversion was a primary conversion option for space reactors because of its: (1) high operating temperature; (2) lack of moving parts; (3) modularity; (4) established technology; and (5) development potential.

  10. Porous Pt Nanoparticles with High Near-Infrared Photothermal Conversion Efficiencies for Photothermal Therapy.

    PubMed

    Zhu, Xiao-Ming; Wan, Hong-Ye; Jia, Henglei; Liu, Liang; Wang, Jianfang

    2016-12-01

    Plasmonic nanostructures are of potential in acting as a type of optical agents for cancer photothermal therapy. To effectively function as photothermal therapy agents, plasmonic nanostructures are strongly desired to have good biocompatibility and high photothermal conversion efficiencies. In this study, poly(diallyldimethylammonium chloride)-coated porous Pt nanoparticles are synthesized for photothermal therapy. The Pt nanoparticles possess broadband near-infrared light absorption in the range from 650 to 1200 nm, therefore allowing for selecting different laser wavelengths for photothermal therapy. The as-prepared Pt nanoparticles exhibit remarkable photothermal conversion efficiencies under 809 and 980 nm laser irradiation. In vitro studies indicate that the Pt nanoparticles display good biocompatibility and high cellular uptake efficiencies through an endocytosis pathway. Photothermal heating using 808 nm laser irradiation (>7.0 W cm(-2) , 3 min) leads to notable cytotoxic effect, and more than 70% of cells are photothermally ablated after 3 min irradiation at 8.4 W cm(-2) . Furthermore, simultaneous application of photothermal therapy synergistically enhances the cytotoxicity of an anti-cancer drug doxorubicin. Therefore, the porous Pt nanoparticles have great potential as an attractive photothermal agent for cancer therapy.

  11. Trophic mode conversion and nitrogen deprivation of microalgae for high ammonium removal from synthetic wastewater.

    PubMed

    Wang, Jinghan; Zhou, Wenguang; Yang, Haizhen; Wang, Feng; Ruan, Roger

    2015-11-01

    In this study, a well-controlled three-stage process was proposed for high ammonium removal from synthetic wastewater using selected promising microalgal strain UMN266. Three trophic modes (photoautotrophy, heterotrophy, and mixotrophy), two N sufficiency conditions (N sufficient and N deprived), two inoculum modes (photoautotrophic and heterotrophic), and different NH4(+)-N concentrations were compared to investigate the effect of trophic mode conversion and N deprivation on high NH4(+)-N removal by UMN266. Results showed that photoautotrophic inoculum with trophic mode conversion from heterotrophy to photoautotrophy and N deprivation in Stage 2 turned was the optimum plan for NH4(+)-N removal, and average removal rates were 12.4 and 19.1mg/L/d with initial NH4(+)-N of 80 and 160mg/L in Stage 3. Mechanism investigations based on algal biomass carbon (C) and N content, cellular composition, and starch content confirmed the above optimum plan and potential of UMN266 as bioethanol feedstock.

  12. Energy conversion approaches and materials for high-efficiency photovoltaics.

    PubMed

    Green, Martin A; Bremner, Stephen P

    2016-12-20

    The past five years have seen significant cost reductions in photovoltaics and a correspondingly strong increase in uptake, with photovoltaics now positioned to provide one of the lowest-cost options for future electricity generation. What is becoming clear as the industry develops is that area-related costs, such as costs of encapsulation and field-installation, are increasingly important components of the total costs of photovoltaic electricity generation, with this trend expected to continue. Improved energy-conversion efficiency directly reduces such costs, with increased manufacturing volume likely to drive down the additional costs associated with implementing higher efficiencies. This suggests the industry will evolve beyond the standard single-junction solar cells that currently dominate commercial production, where energy-conversion efficiencies are fundamentally constrained by Shockley-Queisser limits to practical values below 30%. This Review assesses the overall prospects for a range of approaches that can potentially exceed these limits, based on ultimate efficiency prospects, material requirements and developmental outlook.

  13. Energy conversion approaches and materials for high-efficiency photovoltaics

    NASA Astrophysics Data System (ADS)

    Green, Martin A.; Bremner, Stephen P.

    2017-01-01

    The past five years have seen significant cost reductions in photovoltaics and a correspondingly strong increase in uptake, with photovoltaics now positioned to provide one of the lowest-cost options for future electricity generation. What is becoming clear as the industry develops is that area-related costs, such as costs of encapsulation and field-installation, are increasingly important components of the total costs of photovoltaic electricity generation, with this trend expected to continue. Improved energy-conversion efficiency directly reduces such costs, with increased manufacturing volume likely to drive down the additional costs associated with implementing higher efficiencies. This suggests the industry will evolve beyond the standard single-junction solar cells that currently dominate commercial production, where energy-conversion efficiencies are fundamentally constrained by Shockley-Queisser limits to practical values below 30%. This Review assesses the overall prospects for a range of approaches that can potentially exceed these limits, based on ultimate efficiency prospects, material requirements and developmental outlook.

  14. Selectivity of Enzymatic Conversion of Oligonucleotide Probes during Nucleotide Polymorphism Analysis of DNA

    PubMed Central

    Vinogradova, O.A.

    2010-01-01

    The analysis of DNA nucleotide polymorphisms is one of the main goals of DNA diagnostics. DNA–dependent enzymes (DNA polymerases and DNA ligases) are widely used to enhance the sensitivity and reliability of systems intended for the detection of point mutations in genetic material. In this article, we have summarized the data on the selectiveness of DNA–dependent enzymes and on the structural factors in enzymes and DNA which influence the effectiveness of mismatch discrimination during enzymatic conversion of oligonucleotide probes on a DNA template. The data presented characterize the sensitivity of a series of DNA–dependent enzymes that are widely used in the detection of noncomplementary base pairs in nucleic acid substrate complexes. We have analyzed the spatial properties of the enzyme–substrate complexes. These properties are vital for the enzymatic reaction and the recognition of perfect DNA–substrates. We also discuss relevant approaches to increasing the selectivity of enzyme–dependent reactions. These approaches involve the use of modified oligonucleotide probes which “disturb” the native structure of the DNA–substrate complexes. PMID:22649627

  15. Design and synthesis of copper-cobalt catalysts for the selective conversion of synthesis gas to ethanol and higher alcohols.

    PubMed

    Prieto, Gonzalo; Beijer, Steven; Smith, Miranda L; He, Ming; Au, Yuen; Wang, Zi; Bruce, David A; de Jong, Krijn P; Spivey, James J; de Jongh, Petra E

    2014-06-16

    Combining quantum-mechanical simulations and synthesis tools allows the design of highly efficient CuCo/MoO(x) catalysts for the selective conversion of synthesis gas (CO+H2) into ethanol and higher alcohols, which are of eminent interest for the production of platform chemicals from non-petroleum feedstocks. Density functional theory calculations coupled to microkinetic models identify mixed Cu-Co alloy sites, at Co-enriched surfaces, as ideal for the selective production of long-chain alcohols. Accordingly, a versatile synthesis route is developed based on metal nanoparticle exsolution from a molybdate precursor compound whose crystalline structure isomorphically accommodates Cu(2+) and Co(2+) cations in a wide range of compositions. As revealed by energy-dispersive X-ray nanospectroscopy and temperature-resolved X-ray diffraction, superior mixing of Cu and Co species promotes formation of CuCo alloy nanocrystals after activation, leading to two orders of magnitude higher yield to high alcohols than a benchmark CuCoCr catalyst. Substantiating simulations, the yield to high alcohols is maximized in parallel to the CuCo alloy contribution, for Co-rich surface compositions, for which Cu phase segregation is prevented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Contrasting evolutionary histories of MHC class I and class II loci in grouse--effects of selection and gene conversion.

    PubMed

    Minias, P; Bateson, Z W; Whittingham, L A; Johnson, J A; Oyler-McCance, S; Dunn, P O

    2016-05-01

    Genes of the major histocompatibility complex (MHC) encode receptor molecules that are responsible for recognition of intracellular and extracellular pathogens (class I and class II genes, respectively) in vertebrates. Given the different roles of class I and II MHC genes, one might expect the strength of selection to differ between these two classes. Different selective pressures may also promote different rates of gene conversion at each class. Despite these predictions, surprisingly few studies have looked at differences between class I and II genes in terms of both selection and gene conversion. Here, we investigated the molecular evolution of MHC class I and II genes in five closely related species of prairie grouse (Centrocercus and Tympanuchus) that possess one class I and two class II loci. We found striking differences in the strength of balancing selection acting on MHC class I versus class II genes. More than half of the putative antigen-binding sites (ABS) of class II were under positive or episodic diversifying selection, compared with only 10% at class I. We also found that gene conversion had a stronger role in shaping the evolution of MHC class II than class I. Overall, the combination of strong positive (balancing) selection and frequent gene conversion has maintained higher diversity of MHC class II than class I in prairie grouse. This is one of the first studies clearly demonstrating that macroevolutionary mechanisms can act differently on genes involved in the immune response against intracellular and extracellular pathogens.

  17. Contrasting evolutionary histories of MHC class I and class II loci in grouse—effects of selection and gene conversion

    PubMed Central

    Minias, P; Bateson, Z W; Whittingham, L A; Johnson, J A; Oyler-McCance, S; Dunn, P O

    2016-01-01

    Genes of the major histocompatibility complex (MHC) encode receptor molecules that are responsible for recognition of intracellular and extracellular pathogens (class I and class II genes, respectively) in vertebrates. Given the different roles of class I and II MHC genes, one might expect the strength of selection to differ between these two classes. Different selective pressures may also promote different rates of gene conversion at each class. Despite these predictions, surprisingly few studies have looked at differences between class I and II genes in terms of both selection and gene conversion. Here, we investigated the molecular evolution of MHC class I and II genes in five closely related species of prairie grouse (Centrocercus and Tympanuchus) that possess one class I and two class II loci. We found striking differences in the strength of balancing selection acting on MHC class I versus class II genes. More than half of the putative antigen-binding sites (ABS) of class II were under positive or episodic diversifying selection, compared with only 10% at class I. We also found that gene conversion had a stronger role in shaping the evolution of MHC class II than class I. Overall, the combination of strong positive (balancing) selection and frequent gene conversion has maintained higher diversity of MHC class II than class I in prairie grouse. This is one of the first studies clearly demonstrating that macroevolutionary mechanisms can act differently on genes involved in the immune response against intracellular and extracellular pathogens. PMID:26860199

  18. Contrasting evolutionary histories of MHC class I and class II loci in grouse—Effects of selection and gene conversion

    USGS Publications Warehouse

    Minias, Piotr; Bateson, Zachary W; Whittingham, Linda A; Johnson, Jeff A.; Oyler-McCance, Sara J.; Dunn, Peter O

    2016-01-01

    Genes of the major histocompatibility complex (MHC) encode receptor molecules that are responsible for recognition of intracellular and extracellular pathogens (class I and class II genes, respectively) in vertebrates. Given the different roles of class I and II MHC genes, one might expect the strength of selection to differ between these two classes. Different selective pressures may also promote different rates of gene conversion at each class. Despite these predictions, surprisingly few studies have looked at differences between class I and II genes in terms of both selection and gene conversion. Here, we investigated the molecular evolution of MHC class I and II genes in five closely related species of prairie grouse (Centrocercus and Tympanuchus) that possess one class I and two class II loci. We found striking differences in the strength of balancing selection acting on MHC class I versus class II genes. More than half of the putative antigen-binding sites (ABS) of class II were under positive or episodic diversifying selection, compared with only 10% at class I. We also found that gene conversion had a stronger role in shaping the evolution of MHC class II than class I. Overall, the combination of strong positive (balancing) selection and frequent gene conversion has maintained higher diversity of MHC class II than class I in prairie grouse. This is one of the first studies clearly demonstrating that macroevolutionary mechanisms can act differently on genes involved in the immune response against intracellular and extracellular pathogens.

  19. High-Performance Photothermal Conversion of Narrow-Bandgap Ti2 O3 Nanoparticles.

    PubMed

    Wang, Juan; Li, Yangyang; Deng, Lin; Wei, Nini; Weng, Yakui; Dong, Shuai; Qi, Dianpeng; Qiu, Jun; Chen, Xiaodong; Wu, Tom

    2017-01-01

    Ti2 O3 nanoparticles with high performance of photothermal conversion are demonstrated for the first time. Benefiting from the nanosize and narrow-bandgap features, the Ti2 O3 nanoparticles possess strong light absorption and nearly 100% internal solar-thermal conversion efficiency. Furthermore, Ti2 O3 -nanoparticle-based thin film shows potential use in seawater desalination and purification.

  20. Treating Culture: What 11 High School EFL Conversation Textbooks in South Korea Do

    ERIC Educational Resources Information Center

    Kang-Young, Lee

    2009-01-01

    This study collects 11 high-school EFL conversation textbooks used in Korea and sees how the textbooks teach culture since language learning is closely tied to culture learning (Kramsch, 2002). Conversation materials are chosen because socio-cultural values and norms are best acquired during the process of interaction (Scollon & Scollon,…

  1. Conversation Compass: A Teacher's Guide to High-Quality Language Learning in Young Children

    ERIC Educational Resources Information Center

    Curenton, Stephanie M.

    2016-01-01

    Classroom conversation plays an important role in the development of children's language and reasoning. However, studies show that classroom talk relies too much on directives and close-ended questions. "Conversation Compass" provides the tools to strengthen your language-learning environment: (1) The Compass: guide high-quality…

  2. Increasing Conversational Interactions between Verbal High School Students with Autism and Their Peers without Disabilities

    ERIC Educational Resources Information Center

    Hughes, Carolyn; Bernstein, Rebekah T.; Kaplan, Lauren M.; Reilly, Caitlin M.; Brigham, Nicolette L.; Cosgriff, Joseph C.; Boykin, Michaela P.

    2013-01-01

    Self-prompted communication books were used in combination with conversational peer orientation to increase conversational interactions of verbal high school students with autism or autistic-like behavior with their peers without disabilities. Previous investigators have used communication books only with students with autism or intellectual…

  3. Pt nanocatalysts supported on reduced graphene oxide for selective conversion of cellulose or cellobiose to sorbitol.

    PubMed

    Wang, Ding; Niu, Wenqi; Tan, Minghui; Wu, Mingbo; Zheng, Xuejun; Li, Yanpeng; Tsubaki, Noritatsu

    2014-05-01

    Pt nanocatalysts loaded on reduced graphene oxide (Pt/RGO) were prepared by means of a convenient microwave-assisted reduction approach with ethylene glycol as reductant. The conversion of cellulose or cellobiose into sorbitol was used as an application reaction to investigate their catalytic performance. Various metal nanocatalysts loaded on RGO were compared and RGO-supported Pt exhibited the highest catalytic activity with 91.5 % of sorbitol yield from cellobiose. The catalytic performances of Pt nanocatalysts supported on different carbon materials or on silica support were also compared. The results showed that RGO was the best catalyst support, and the yield of sorbitol was as high as 91.5 % from cellobiose and 58.9 % from cellulose, respectively. The improvement of catalytic activity was attributed to the appropriate Pt particle size and hydrogen spillover effect of Pt/RGO catalyst. Interestingly, the size and dispersion of supported Pt particles could be easily regulated by convenient adjustment of the microwave heating temperature. The catalytic performance was found to initially increase and then decrease with increasing particle size. The optimum Pt particle size was 3.6 nm. These findings may offer useful guidelines for designing novel catalysts with beneficial catalytic performance for biomass conversion.

  4. High temperature solar selective coatings

    DOEpatents

    Kennedy, Cheryl E

    2014-11-25

    Improved solar collectors (40) comprising glass tubing (42) attached to bellows (44) by airtight seals (56) enclose solar absorber tubes (50) inside an annular evacuated space (54. The exterior surfaces of the solar absorber tubes (50) are coated with improved solar selective coatings {48} which provide higher absorbance, lower emittance and resistance to atmospheric oxidation at elevated temperatures. The coatings are multilayered structures comprising solar absorbent layers (26) applied to the meta surface of the absorber tubes (50), typically stainless steel, topped with antireflective Savers (28) comprising at least two layers 30, 32) of refractory metal or metalloid oxides (such as titania and silica) with substantially differing indices of refraction in adjacent layers. Optionally, at least one layer of a noble metal such as platinum can be included between some of the layers. The absorbent layers cars include cermet materials comprising particles of metal compounds is a matrix, which can contain oxides of refractory metals or metalloids such as silicon. Reflective layers within the coating layers can comprise refractory metal silicides and related compounds characterized by the formulas TiSi. Ti.sub.3SiC.sub.2, TiAlSi, TiAN and similar compounds for Zr and Hf. The titania can be characterized by the formulas TiO.sub.2, Ti.sub.3O.sub.5. TiOx or TiO.sub.xN.sub.1-x with x 0 to 1. The silica can be at least one of SiO.sub.2, SiO.sub.2x or SiO.sub.2xN.sub.1-x with x=0 to 1.

  5. Radiation-induced high-temperature conversion of cellulose.

    PubMed

    Ponomarev, Alexander V; Ershov, Boris G

    2014-10-21

    Thermal decomposition of cellulose can be upgraded by means of an electron-beam irradiation to produce valuable organic products via chain mechanisms. The samples being irradiated decompose effectively at temperatures below the threshold of pyrolysis inception. Cellulose decomposition resembles local "explosion" of the glucopyranose unit when fast elimination of carbon dioxide and water precede formation of residual carbonyl or carboxyl compounds. The dry distillation being performed during an irradiation gives a liquid condensate where furfural and its derivatives are dominant components. Excessively fast heating is adverse, as it results in a decrease of the yield of key organic products because pyrolysis predominates over the radiolytic-controlled decomposition of feedstock. Most likely, conversion of cellulose starts via radiolytic formation of macroradicals do not conform with each other, resulting in instability of the macroradical. As a consequence, glucosidic bond cleavage, elimination of light fragments (water, carbon oxides, formaldehyde, etc.) and formation of furfural take place.

  6. Radiative energy receiver for high performance energy conversion cycles

    NASA Technical Reports Server (NTRS)

    Rault, D.; Hertzberg, A.

    1982-01-01

    An analysis of gas dynamic processes pertinent to the functioning of earth-based and space-based solar electric power plants is presented, with attention given to potassium vapor as the working fluid. A device is described which features focused photon absorption by a nontransparent flowing gas. The feed flow is effected around the outside walls of a cavity receiver to raise efficiencies by trapping reemitted energy. A theoretical study of the interaction of a photon flux with a coaxial particle flux was performed, with the receiver flow treated as a Graetz flow. The critical parameters were defined, including a figure of merit as the gas enthalpy increase to absorbable energy ratio. A small-scale laboratory model was tested in comparison with the theoretically obtained values. Less than 15% of the absorbed energy was lost through dissipation while an 80% conversion efficiency was attained.

  7. Radiative energy receiver for high performance energy conversion cycles

    NASA Technical Reports Server (NTRS)

    Rault, D.; Hertzberg, A.

    1982-01-01

    An analysis of gas dynamic processes pertinent to the functioning of earth-based and space-based solar electric power plants is presented, with attention given to potassium vapor as the working fluid. A device is described which features focused photon absorption by a nontransparent flowing gas. The feed flow is effected around the outside walls of a cavity receiver to raise efficiencies by trapping reemitted energy. A theoretical study of the interaction of a photon flux with a coaxial particle flux was performed, with the receiver flow treated as a Graetz flow. The critical parameters were defined, including a figure of merit as the gas enthalpy increase to absorbable energy ratio. A small-scale laboratory model was tested in comparison with the theoretically obtained values. Less than 15% of the absorbed energy was lost through dissipation while an 80% conversion efficiency was attained.

  8. Mechanistic Insights into the Structure-Dependent Selectivity of Catalytic Furfural Conversion on Platinum Catalysts

    SciTech Connect

    Cai, Qiuxia; Wang, Jianguo; Wang, Yang-Gang; Mei, Donghai

    2015-11-01

    The effects of structure and size on the selectivity of catalytic furfural conversion over supported Pt catalysts in the presence of hydrogen have been studied using first principles density functional theory (DFT) calculations and microkinetic modeling. Four Pt model systems, i.e., periodic Pt(111), Pt(211) surfaces, as well as small nanoclusters (Pt13 and Pt55) are chosen to represent the terrace, step, and corner sites of Pt nanoparticles. Our DFT results show that the reaction routes for furfural hydrogenation and decarbonylation are strongly dependent on the type of reactive sites, which lead to the different selectivity. On the basis of the size-dependent site distribution rule, we correlate the site distributions as a function of the Pt particle size. Our microkinetic results indicate the critical particle size that controls the furfural selectivity is about 1.0 nm, which is in good agreement with the reported experimental value under reaction conditions. This work was supported by National Basic Research Program of China (973 Program) (2013CB733501) and the National Natural Science Foundation of China (NSFC-21306169, 21176221, 21136001, 21101137 and 91334103). This work was also partially supported by the US Department of Energy (DOE), the Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility located at Pacific Northwest National Laboratory (PNNL) and sponsored by DOE’s Office of Biological and Environmental Research.

  9. Synthesis of Co-based bimetallic nanocrystals with one-dimensional structure for selective control on syngas conversion

    NASA Astrophysics Data System (ADS)

    Ba, Rongbin; Zhao, Yonghui; Yu, Lujing; Song, Jianjun; Huang, Shuangshuang; Zhong, Liangshu; Sun, Yuhan; Zhu, Yan

    2015-07-01

    Co-based bimetallic nanocrystals with one-dimensional (1D) branches were synthesized by the heterogeneous nucleation of Co atoms onto prenucleated seeds, such as Pd or Cu, through a facile wet-chemical route. The peripheral branches (rod-like) of the Co-Pd and Co-Cu nanocrystals were outspread along the (001) direction and were enclosed by (101) facets. By switching the prenucleated metals to form robust Co-Pd or Co-Cu bimetallic nanocatalysts, the selectivity of CO hydrogenation could be adjusted purposely towards heavy paraffins, light olefins or oxygenates. The Anderson-Schulz-Flory chain-lengthening probabilities for products were up to 0.9 over Co-Pd nanocrystals, showing that long-chain hydrocarbons can be formed with high selectivity using the targeted design of Co-Pd nanocrystal catalysts. These Co-based bimetallic nanocrystals with a 1D structure exhibited superior catalytic activities over the corresponding Co-based nanoparticles for synthesis gas conversion.Co-based bimetallic nanocrystals with one-dimensional (1D) branches were synthesized by the heterogeneous nucleation of Co atoms onto prenucleated seeds, such as Pd or Cu, through a facile wet-chemical route. The peripheral branches (rod-like) of the Co-Pd and Co-Cu nanocrystals were outspread along the (001) direction and were enclosed by (101) facets. By switching the prenucleated metals to form robust Co-Pd or Co-Cu bimetallic nanocatalysts, the selectivity of CO hydrogenation could be adjusted purposely towards heavy paraffins, light olefins or oxygenates. The Anderson-Schulz-Flory chain-lengthening probabilities for products were up to 0.9 over Co-Pd nanocrystals, showing that long-chain hydrocarbons can be formed with high selectivity using the targeted design of Co-Pd nanocrystal catalysts. These Co-based bimetallic nanocrystals with a 1D structure exhibited superior catalytic activities over the corresponding Co-based nanoparticles for synthesis gas conversion. Electronic supplementary

  10. Directed surfaces structures and interfaces for enhanced electrocatalyst activity, selectivity, and stability for energy conversion reactions

    SciTech Connect

    Jaramillo, Thomas F.

    2016-04-20

    In this project, we have employed a systematic approach to develop active, selective, and stable catalyst materials for important electrochemical reactions involving energy conversion. In particular, we have focused our attention on developing active catalyst materials for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). HER: We have synthesized and investigated several highly active and acid stable non-precious metal HER catalysts, including: [Mo3S13]2- nanoclusters (Nature Chemistry, 2014) and molybdenum phosphosulfide (MoP|S) (Angewandte Chemie, 2014). We have also aimed to engineer these catalyst formulations in a membrane electrode assembly (MEA) for fundamental studies of water electrolysis at high current densities, approximately 1 A/cm2 (ChemSusChem, 2015). We furthermore investigated transition metal phosphide (TMP) catalysts for HER by a combined experimental–theoretical approach (Energy & Environmental Science, 2015). By synthesizing different TMPs and comparing experimentally determined HER activities with the hydrogen adsorption free energies, ΔGH, calculated by density functional theory, we showed that the TMPs follow a volcano relationship for the HER. Using our combined experimental–theoretical model, we predicted that the mixed metal TMP, Fe0.5Co0.5P, should have a near-optimal ΔGH. We synthesized several mixtures of Co and Fe phosphides alloys and confirmed that Fe0.5Co0.5P exhibits the highest HER activity of the investigated TMPs (Energy & Environmental Science, 2015). The understanding gained as to how to improve catalytic activity for the HER, particularly for non-precious metal materials, is important to DOE targets for sustainable H2 production. OER: We have developed a SrIrO3/IrOx catalyst for acidic conditions (submitted, 2016). The Sr

  11. Single-site trinuclear copper oxygen clusters in mordenite for selective conversion of methane to methanol

    PubMed Central

    Grundner, Sebastian; Markovits, Monica A.C.; Li, Guanna; Tromp, Moniek; Pidko, Evgeny A.; Hensen, Emiel J.M.; Jentys, Andreas; Sanchez-Sanchez, Maricruz; Lercher, Johannes A.

    2015-01-01

    Copper-exchanged zeolites with mordenite structure mimic the nuclearity and reactivity of active sites in particulate methane monooxygenase, which are enzymes able to selectively oxidize methane to methanol. Here we show that the mordenite micropores provide a perfect confined environment for the highly selective stabilization of trinuclear copper-oxo clusters that exhibit a high reactivity towards activation of carbon–hydrogen bonds in methane and its subsequent transformation to methanol. The similarity with the enzymatic systems is also implied from the similarity of the reversible rearrangements of the trinuclear clusters occurring during the selective transformations of methane along the reaction path towards methanol, in both the enzyme system and copper-exchanged mordenite. PMID:26109507

  12. Selective catalysis for cellulose conversion to lactic acid and other α-hydroxy acids.

    PubMed

    Dusselier, Michiel; Sels, Bert F

    2014-01-01

    This review discusses topical chemical routes and their catalysis for the conversion of cellulose, hexoses, and smaller carbohydrates to lactic acid and other useful α-hydroxy acids. Lactic acid is a top chemical opportunity from carbohydrate biomass as it not only features tremendous potential as a chemical platform molecule; it is also a common building block for commercially employed green solvents and near-commodity bio-plastics. Its current scale fermentative synthesis is sufficient, but it could be considered a bottleneck for a million ton scale breakthrough. Alternative chemical routes are therefore investigated using multifunctional, often heterogeneous, catalysis. Rather than summarizing yields and conditions, this review attempts to guide the reader through the complex reaction networks encountered when synthetic lactates from carbohydrate biomass are targeted. Detailed inspection of the cascade of reactions emphasizes the need for a selective retro-aldol activity in the catalyst. Recently unveiled catalytic routes towards other promising α-hydroxy acids such as glycolic acid, and vinyl and furyl glycolic acids are highlighted as well.

  13. Selective Internal Radiation Therapy (SIRT) as Conversion Therapy for Unresectable Primary Liver Malignancies

    PubMed Central

    Cucchetti, Alessandro; Cappelli, Alberta; Ercolani, Giorgio; Mosconi, Cristina; Cescon, Matteo; Golfieri, Rita; Pinna, Antonio Daniele

    2016-01-01

    Background Many patients with primary liver cancers are not candidates for surgery, and systemic therapies are seldom effective. Selective internal radiation therapy (SIRT) has been shown to obtain partial and even complete response in unresectable primary tumors. As a “side effect”, SIRT can induce contra-lateral liver hypertrophy. Tumor response to SIRT can be sufficient to allow disengagement from normal vital structures whose involvement is the cause of the initial unresectability. The contra-lateral hypertrophy can thereby increase the future liver remnant (FLR) volume to over the safe threshold so that extended hepatectomy can be performed. Summary A review of the available literature was performed to assess the tumor response and liver hypertrophy that can be expected after SIRT, in order to delineate whether SIRTcan play a role in conversion therapy for resectability of primary liver malignancies. Key Message Available data suggest that SIRT in unresectable hepatocellular and cholangiocellular carcinomas can provide a considerable down-sizing of the tumors to possibly allow resection. Hypertrophy of the contra-lateral lobe represents a favorable collateral effect that can help in achieving safer subsequent major hepatectomy. In patients whose FLR volume represents the only surgical concern, portal vein embolization remains the treatment of choice. PMID:27781202

  14. Selective photoreactions in a programmable array microscope (PAM): photoinitiated polymerization, photodecaging, and photochromic conversion.

    PubMed

    Fulwyler, Mack; Hanley, Quentin S; Schnetter, Christoph; Young, Ian T; Jares-Erijman, Elizabeth A; Arndt-Jovin, Donna J; Jovin, Thomas M

    2005-10-01

    Innovative thinking and experimentation were the hallmarks of Mack Fulwyler's approach to research. This report summarizes some of the ideas and their early realizations that he pursued in the field of imaging cytometry, work that was not published before his untimely death, although he composed the initial draft of this report. Included are related experiments implemented in the programmable array microscope (PAM) devised for patterned illumination and detection, the instrument that Mack Fulwyler employed during a sabbatical leave in Göttingen in 1998. Despite being the originator of instrumentation for flow cytometry and sorting, Mack Fulwyler was intensely interested in imaging systems, recognizing their ability to resolve cellular details obscured by the whole cell signals generally acquired in flow. At one point, these interests merged with those of two other authors (I.T.Y. and T.M.J.), leading to the Image Cytometry and Sorting (ICAS) strategy and project. A major goal was uncomplicated rare cell detection and isolation using a sequential process of cellular labeling via suitable probes, whole field imaging, and selective area-restricted photoinduced reactions designed to encapsulate and/or chemically or physically tag cells in a manner permitting subsequent fractionation by bulk techniques. This publication features photoinduced polymerization, photodecaging, photoactivation, and photochromic conversion reactions carried out by Fulwyler and/or the other authors with the PAM, employing operator designated patterns and locations in various samples. Photopolymerization of polyethylene glycol-diacrylate to a gel-like structure allowing the specific selection of objects (cells) for further analysis and processing techniques was the approach explored personally by Mack Fulwyler in relation to the ICAS concept.

  15. High-efficiency microwave photonic harmonic down-conversion with tunable and reconfigurable filtering.

    PubMed

    Liao, Jinxin; Zheng, Xiaoping; Li, Shangyuan; Zhang, Hanyi; Zhou, Bingkun

    2014-12-01

    A new optical-frequency comb-based microwave photonic harmonic down-convertor with tunable and reconfigurable filtering is proposed and experimentally demonstrated. The coherent evenly spaced optical carriers offer harmonic down-conversion for ultrahigh radio frequency signals with low-frequency local oscillator, and construct a tunable and reconfigurable bandpass filter for the intermediate-frequency (IF) signal combined with dispersion. This implementation features high conversion efficiency. Experimental results show the filtered output IF signal has a clean spectrum with high quality. Measured conversion loss is 8.3 dB without extra electrical amplification.

  16. Development and Analysis of Advanced High-Temperature Technology for Nuclear Heat Transport and Power Conversion

    SciTech Connect

    Per F. Peterson

    2010-03-01

    This project by the Thermal Hydraulics Research Laboratory at U.C. Berkeley Studied advanced high-temperature heat transport and power conversion technology, in support of the Nuclear Hydrogen Initiative and Generation IV.

  17. Is the bulk mode conversion important in high density helicon plasma?

    SciTech Connect

    Isayama, Shogo; Hada, Tohru; Shinohara, Shunjiro; Tanikawa, Takao

    2016-06-15

    In a high-density helicon plasma production process, a contribution of Trivelpiece-Gould (TG) wave for surface power deposition is widely accepted. The TG wave can be excited either due to an abrupt density gradient near the plasma edge (surface conversion) or due to linear mode conversion from the helicon wave in a density gradient in the bulk region (bulk mode conversion). By numerically solving the boundary value problem of linear coupling between the helicon and the TG waves in a background with density gradient, we show that the efficiency of the bulk mode conversion strongly depends on the dissipation included in the plasma, and the bulk mode conversion is important when the dissipation is small. Also, by performing FDTD simulation, we show the time evolution of energy flux associated with the helicon and the TG waves.

  18. Plasmon-induced selective carbon dioxide conversion on earth-abundant aluminum-cuprous oxide antenna-reactor nanoparticles.

    PubMed

    Robatjazi, Hossein; Zhao, Hangqi; Swearer, Dayne F; Hogan, Nathaniel J; Zhou, Linan; Alabastri, Alessandro; McClain, Michael J; Nordlander, Peter; Halas, Naomi J

    2017-06-21

    The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways. The antenna-reactor geometry efficiently harnesses the plasmon resonance of aluminum to supply energetic hot-carriers and increases optical absorption in cuprous oxide for selective carbon dioxide conversion to carbon monoxide with visible light. The transition from noble metals to aluminum based antenna-reactor heterostructures in plasmonic photocatalysis provides a sustainable route to high-value chemicals and reaffirms the practical potential of plasmon-mediated chemical transformations.Plasmon-enhanced photocatalysis holds promise for the control of chemical reactions. Here the authors report an Al@Cu2O heterostructure based on earth abundant materials to transform CO2 into CO at significantly milder conditions.

  19. Superstructures and multijunction cells for high efficiency energy conversion

    NASA Technical Reports Server (NTRS)

    Wagner, M.; Leburton, J. P.

    1985-01-01

    Potential applications of superlattices to photovoltaic structures are discussed. A single-bandgap, multijunction cell with selective electrodes for lateral transport of collected carriers is proposed. The concept is based on similar doping superlattice (NIPI) structures. Computer simulations show that by reducing bulk recombination losses, the spectral response of such cells is enhanced, particularly for poor quality materials with short diffusion lengths. Dark current contributions of additional junctions result in a trade-off between short-circuit current and open-circuit voltage as the number of layers is increased. One or two extra junctions appear to be optimal.

  20. Superstructures and multijunction cells for high efficiency energy conversion

    NASA Technical Reports Server (NTRS)

    Wagner, M.; Leburton, J. P.

    1985-01-01

    Potential applications of superlattices to photovoltaic structures are discussed. A single-bandgap, multijunction cell with selective electrodes for lateral transport of collected carriers is proposed. The concept is based on similar doping superlattice (NIPI) structures. Computer simulations show that by reducing bulk recombination losses, the spectral response of such cells is enhanced, particularly for poor quality materials with short diffusion lengths. Dark current contributions of additional junctions result in a trade-off between short-circuit current and open-circuit voltage as the number of layers is increased. One or two extra junctions appear to be optimal.

  1. Elevating the Conversation: Building Professional Community in Small High Schools

    ERIC Educational Resources Information Center

    Gallucci, Chrysan; Wallach, Catherine A.

    2004-01-01

    This report includes observations from the first year of a three-year study of seven small high schools (that exist in converted comprehensive high schools) in Washington State. It discusses the unique characteristics of professional communities that are emerging and examines how these communities are changing teachers expectations for their…

  2. Theory of quantum frequency conversion and type-II parametric down-conversion in the high-gain regime

    NASA Astrophysics Data System (ADS)

    Christ, Andreas; Brecht, Benjamin; Mauerer, Wolfgang; Silberhorn, Christine

    2013-05-01

    Frequency conversion (FC) and type-II parametric down-conversion (PDC) processes serve as basic building blocks for the implementation of quantum optical experiments: type-II PDC enables the efficient creation of quantum states such as photon-number states and Einstein-Podolsky-Rosen (EPR)-states. FC gives rise to technologies enabling efficient atom-photon coupling, ultrafast pulse gates and enhanced detection schemes. However, despite their widespread deployment, their theoretical treatment remains challenging. Especially the multi-photon components in the high-gain regime as well as the explicit time-dependence of the involved Hamiltonians hamper an efficient theoretical description of these nonlinear optical processes. In this paper, we investigate these effects and put forward two models that enable a full description of FC and type-II PDC in the high-gain regime. We present a rigorous numerical model relying on the solution of coupled integro-differential equations that covers the complete dynamics of the process. As an alternative, we develop a simplified model that, at the expense of neglecting time-ordering effects, enables an analytical solution. While the simplified model approximates the correct solution with high fidelity in a broad parameter range, sufficient for many experimental situations, such as FC with low efficiency, entangled photon-pair generation and the heralding of single photons from type-II PDC, our investigations reveal that the rigorous model predicts a decreased performance for FC processes in quantum pulse gate applications and an enhanced EPR-state generation rate during type-II PDC, when EPR squeezing values above 12 dB are considered.

  3. High urine amylase level and the risk of enteric conversion in solitary pancreas transplant recipients.

    PubMed

    Kukla, A; Radosevich, D M; Finger, E B; Kandaswamy, R

    2014-01-01

    Compared with enteric drainage, bladder-drained solitary pancreas transplants can be monitored for rejection by measuring urine amylase levels. However, bladder drainage is associated with a higher risk of infection and metabolic complications, necessitating enteric conversion in about one third of patients. We hypothesized that hypersecreting pancreata with high urine amylase levels have a higher propensity for enteric conversion from an antecedent elevated enzymatic effect on the urinary tract and increased fluid losses. We analyzed the risk for enteric conversion in 312 bladder-drained solitary pancreas transplant recipients. Urine amylase levels at 30 days were used to identify those at risk for enteric conversion. Time-to-event analysis was used to evaluate the risk of enteric conversion at 10 years, adjusting for urine amylase level and other confounding factors. Confounding risk factors statistically related to enteric conversion were incorporated into the multivariable analysis by using Cox proportional hazards regression at 3 years' posttransplant. During the median follow-up of 184.6 months, 31% of recipients underwent duct conversion. A majority of recipients (84.5%) who required duct conversion were primary transplants. The 30-day median urine amylase level was 1749 IU/h (quartile 1, <777 IU/h; quartile 3, ≥3272 IU/h). Using receiver operating characteristic analysis, it was determined that urine amylase levels >3272 IU/h had the greatest specificity for predicting risk of enteric conversion. In the multivariate analysis, high urine amylase levels increased the risk of enteric conversion only in repeated pancreas transplants. Primary transplants are more likely to undergo enteric conversion than retransplants. High urine amylase levels increase the risk of enteric conversion in retransplants only, and therefore this enzyme alone cannot serve as the sole predictor for conversion in primary transplants. Other factors, such as fluid and bicarbonate

  4. A GPU based high-definition ultrasound digital scan conversion algorithm

    NASA Astrophysics Data System (ADS)

    Zhao, Mingchang; Mo, Shanjue

    2010-02-01

    Digital scan conversion algorithm is the most computational intensive part of B-mode ultrasound imaging. Traditionally, in order to meet the requirements of real-time imaging, digital scan conversion algorithm often traded off image quality for speed, such as the use of simple image interpolation algorithm, the use of look-up table to carry out polar coordinates transform and logarithmic compression. This paper presents a GPU-based high-definition real-time ultrasound digital scan conversion algorithm implementation. By rendering appropriate proxy geometry, we can implement a high precision digital scan conversion pipeline, including polar coordinates transform, bi-cubic image interpolation, high dynamic range tone reduction, line average and frame persistence FIR filtering, 2D post filtering, fully in the fragment shader of GPU at real-time speed. The proposed method shows the possibility of updating exist FPGA or ASIC based digital scan conversion implementation to low cost GPU based high-definition digital scan conversion implementation.

  5. Highly active and stable iron Fischer-Tropsch catalyst for synthesis gas conversion to liquid fuels

    SciTech Connect

    Bukur, D.B.; Lang, X.

    1999-09-01

    A precipitated iron Fischer-Tropsch (F-T) catalyst (100 Fe/3 Cu/4 K/16 SiO{sub 2} on mass basis) was tested in a stirred tank slurry reactor under reaction conditions representative of industrial practice using CO-rich synthesis gas (260 C, 1.5--2.2 MPa, H{sub 2}/CO = 2/3). Repeatability of performance and reproducibility of catalyst preparation procedure were successfully demonstrated on a laboratory scale. Catalyst productivity was increased by operating at higher synthesis pressure while maintaining a constant contact time in the reactor and through the use of different catalyst pretreatment procedures. In one of the tests (run SA-2186), the catalyst productivity was 0.86 (g hydrocarbons/g Fe/h) at syngas conversion of 79%, methane selectivity of 3% (weight percent of total hydrocarbons produced), and C{sub 5}+ hydrocarbon selectivity of 83 wt %. This represents a substantial improvement in productivity in comparison to state-of-the-art iron F-T catalysts. This catalyst is ideally suited for production of high-quality diesel fuels and C{sub 2}-c{sub 4} olefins from a coal-derived synthesis gas.

  6. Experimental study of high sensitivity infrared spectrometer with waveguide-based up-conversion detector(1).

    PubMed

    Ma, Lijun; Slattery, Oliver; Tang, Xiao

    2009-08-03

    We have developed an up-conversion spectrometer for signals at single photon levels near the infrared region based on a tunable up-conversion detector that uses a periodically poled lithium niobate waveguide as the conversion medium. We also experimentally studied its characteristics including sensitivity, dark count rate, spectral scan speed, signal transfer function of the waveguide, and polarization sensitivity. The overall single photon detection efficiency of the up-conversion spectrometer is about 32%. With its ultra high sensitivity the spectrometer can measure spectra for signals at a level as low as -126 dBm. We have demonstrated the spectrometers high sensitivity by measuring the spectrum of a greatly attenuated multimode emission from a laser diode at the 1310 nm band.

  7. Thermophotovoltaic and photovoltaic conversion at high-flux densities

    SciTech Connect

    Coutts, T.J.; Ward, J.S.

    1999-10-01

    The authors first discuss the similarities between generation of electricity using thermophotovoltaic (TPV) and high-optical-concentration solar photovoltaic (PC) devices. Following this, the authors consider power losses due to above- and below-bandgap photons, and estimate the ideal bandgap by minimizing the sum of these, for a 6,000 K black-body spectrum. The ideal bandgap, based on this approach, is less than that previously predicted, which could have a significant influence on the performance of devices and systems. To reduce the losses, the authors show that the low-energy photons may be removed from both types of cells and consider the specific case of a back-surface reflector. This approach to the management of waste heat may offer a useful additional tool with which to facilitate the design of high-photo-flux solar cells. In the case of the high-energy photons and the associated problem of thermalization of hot electrons, however, the heat must be removed by other means, and the authors consider the applicability of microchannel cooling systems. These appear to have the potential to handle thermal loads at least several times those generated by 1,000 times concentrators, or by black-body TPV radiators at a temperature of far greater than 1,500 K. The authors go on to consider the management of the very high currents generated in both concentrator TPV and PV systems and discuss the concept of the monolithically integrated minimodule.

  8. Teaching Writing in High School and College: Conversations and Collaborations.

    ERIC Educational Resources Information Center

    Thompson, Thomas C., Ed.

    Addressing what teachers can do to prepare high school students to write effectively in college, this book presents 15 narratives and studies suggesting that secondary-postsecondary partnerships and exchanges can significantly improve students' ability to succeed at college-level writing tasks. Essays in section I, Trading Places, are: (1)…

  9. Signatures of Selection and Gene Conversion Associated with Human Color Vision Variation

    PubMed Central

    Verrelli, Brian C.; Tishkoff, Sarah A.

    2004-01-01

    Trichromatic color vision in humans results from the combination of red, green, and blue photopigment opsins. Although color vision genes have been the targets of active molecular and psychophysical research on color vision abnormalities, little is known about patterns of normal genetic variation in these genes among global human populations. The current study presents nucleotide sequence analyses and tests of neutrality for a 5.5-kb region of the X-linked long-wave “red” opsin gene (OPN1LW) in 236 individuals from ethnically diverse human populations. Our analysis of the recombination landscape across OPN1LW reveals an unusual haplotype structure associated with amino acid replacement variation in exon 3 that is consistent with gene conversion. Compared with the absence of OPN1LW amino acid replacement fixation since divergence from chimpanzee, the human population exhibits a significant excess of high-frequency OPN1LW replacements. Our results suggest that subtle changes in L-cone opsin wavelength absorption may have been adaptive during human evolution. PMID:15252758

  10. Power conversion distribution system using a resonant high-frequency AC link

    NASA Technical Reports Server (NTRS)

    Sood, P. K.; Lipo, T. A.

    1986-01-01

    Static power conversion systems based on a resonant high frequency (HF) link offers a significant reduction in the size and weight of the equipment over that achieved with conventional approaches, especially when multiple sources and loads are to be integrated. A faster system response and absence of audible noise are the other principal characteristics of such systems. A conversion configuration based on a HF link which is suitable for applications requiring distributed power is proposed.

  11. Fast and selective sugar conversion to alkyl lactate and lactic acid with bifunctional carbon-silica catalysts.

    PubMed

    de Clippel, Filip; Dusselier, Michiel; Van Rompaey, Ruben; Vanelderen, Pieter; Dijkmans, Jan; Makshina, Ekaterina; Giebeler, Lars; Oswald, Steffen; Baron, Gino V; Denayer, Joeri F M; Pescarmona, Paolo P; Jacobs, Pierre A; Sels, Bert F

    2012-06-20

    A novel catalyst design for the conversion of mono- and disaccharides to lactic acid and its alkyl esters was developed. The design uses a mesoporous silica, here represented by MCM-41, which is filled with a polyaromatic to graphite-like carbon network. The particular structure of the carbon-silica composite allows the accommodation of a broad variety of catalytically active functions, useful to attain cascade reactions, in a readily tunable pore texture. The significance of a joint action of Lewis and weak Brønsted acid sites was studied here to realize fast and selective sugar conversion. Lewis acidity is provided by grafting the silica component with Sn(IV), while weak Brønsted acidity originates from oxygen-containing functional groups in the carbon part. The weak Brønsted acid content was varied by changing the amount of carbon loading, the pyrolysis temperature, and the post-treatment procedure. As both catalytic functions can be tuned independently, their individual role and optimal balance can be searched for. It was thus demonstrated for the first time that the presence of weak Brønsted acid sites is crucial in accelerating the rate-determining (dehydration) reaction, that is, the first step in the reaction network from triose to lactate. Composite catalysts with well-balanced Lewis/Brønsted acidity are able to convert the trioses, glyceraldehyde and dihydroxyacetone, quantitatively into ethyl lactate in ethanol with an order of magnitude higher reaction rate when compared to the Sn grafted MCM-41 reference catalyst. Interestingly, the ability to tailor the pore architecture further allows the synthesis of a variety of amphiphilic alkyl lactates from trioses and long chain alcohols in moderate to high yields. Finally, direct lactate formation from hexoses, glucose and fructose, and disaccharides composed thereof, sucrose, was also attempted. For instance, conversion of sucrose with the bifunctional composite catalyst yields 45% methyl lactate in

  12. High-Power Microwave Transmission and Mode Conversion Program

    SciTech Connect

    Vernon, Ronald J.

    2015-08-14

    This is a final technical report for a long term project to develop improved designs and design tools for the microwave hardware and components associated with the DOE Plasma Fusion Program. We have developed basic theory, software, fabrication techniques, and low-power measurement techniques for the design of microwave hardware associated gyrotrons, microwave mode converters and high-power microwave transmission lines. Specifically, in this report we discuss our work on designing quasi-optical mode converters for single and multiple frequencies, a new method for the analysis of perturbed-wall waveguide mode converters, perturbed-wall launcher design for TE0n mode gyrotrons, quasi-optical traveling-wave resonator design for high-power testing of microwave components, and possible improvements to the HSX microwave transmission line.

  13. High speed analog-to-digital conversion with silicon photonics

    NASA Astrophysics Data System (ADS)

    Holzwarth, C. W.; Amatya, R.; Araghchini, M.; Birge, J.; Byun, H.; Chen, J.; Dahlem, M.; DiLello, N. A.; Gan, F.; Hoyt, J. L.; Ippen, E. P.; Kärtner, F. X.; Khilo, A.; Kim, J.; Kim, M.; Motamedi, A.; Orcutt, J. S.; Park, M.; Perrott, M.; Popovic, M. A.; Ram, R. J.; Smith, H. I.; Zhou, G. R.; Spector, S. J.; Lyszczarz, T. M.; Geis, M. W.; Lennon, D. M.; Yoon, J. U.; Grein, M. E.; Schulein, R. T.; Frolov, S.; Hanjani, A.; Shmulovich, J.

    2009-02-01

    Sampling rates of high-performance electronic analog-to-digital converters (ADC) are fundamentally limited by the timing jitter of the electronic clock. This limit is overcome in photonic ADC's by taking advantage of the ultra-low timing jitter of femtosecond lasers. We have developed designs and strategies for a photonic ADC that is capable of 40 GSa/s at a resolution of 8 bits. This system requires a femtosecond laser with a repetition rate of 2 GHz and timing jitter less than 20 fs. In addition to a femtosecond laser this system calls for the integration of a number of photonic components including: a broadband modulator, optical filter banks, and photodetectors. Using silicon-on-insulator (SOI) as the platform we have fabricated these individual components. The silicon optical modulator is based on a Mach-Zehnder interferometer architecture and achieves a VπL of 2 Vcm. The filter banks comprise 40 second-order microring-resonator filters with a channel spacing of 80 GHz. For the photodetectors we are exploring ion-bombarded silicon waveguide detectors and germanium films epitaxially grown on silicon utilizing a process that minimizes the defect density.

  14. Advanced, High Power, Next Scale, Wave Energy Conversion Device

    SciTech Connect

    Mekhiche, Mike; Dufera, Hiz; Montagna, Deb

    2012-10-29

    The project conducted under DOE contract DE‐EE0002649 is defined as the Advanced, High Power, Next Scale, Wave Energy Converter. The overall project is split into a seven‐stage, gated development program. The work conducted under the DOE contract is OPT Stage Gate III work and a portion of Stage Gate IV work of the seven stage product development process. The project effort includes Full Concept Design & Prototype Assembly Testing building on our existing PowerBuoy technology to deliver a device with much increased power delivery. Scaling‐up from 150kW to 500kW power generating capacity required changes in the PowerBuoy design that addressed cost reduction and mass manufacturing by implementing a Design for Manufacturing (DFM) approach. The design changes also focused on reducing PowerBuoy Installation, Operation and Maintenance (IO&M) costs which are essential to reducing the overall cost of energy. In this design, changes to the core PowerBuoy technology were implemented to increase capability and reduce both CAPEX and OPEX costs. OPT conceptually envisaged moving from a floating structure to a seabed structure. The design change from a floating structure to seabed structure would provide the implementation of stroke‐ unlimited Power Take‐Off (PTO) which has a potential to provide significant power delivery improvement and transform the wave energy industry if proven feasible.

  15. High-Voltage, High-Power Gaseous Electronics Switch For Electric Grid Power Conversion

    NASA Astrophysics Data System (ADS)

    Sommerer, Timothy J.

    2014-05-01

    We are developing a high-voltage, high-power gas switch for use in low-cost power conversion terminals on the electric power grid. Direct-current (dc) power transmission has many advantages over alternating current (ac) transmission, but at present the high cost of ac-dc power interconversion limits the use of dc. The gas switch we are developing conducts current through a magnetized cold cathode plasma in hydrogen or helium to reach practical current densities > 1 A/cm2. Thermal and sputter damage of the cathode by the incident ion flux is a major technical risk, and is being addressed through use of a ``self-healing'' liquid metal cathode (eg, gallium). Plasma conditions and cathode sputtering loss are estimated by analyzing plasma spectral emission. A particle-in-cell plasma model is used to understand various aspects of switch operation, including the conduction phase (where plasma densities can exceed 1013 cm-3), the switch-open phase (where the high-voltage must be held against gas breakdown on the left side of Paschen's curve), and the switching transitions (especially the opening process, which is initiated by forming an ion-matrix sheath adjacent to a control grid). The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

  16. High pressure HC1 conversion of cellulose to glucose

    SciTech Connect

    Antonoplis, Robert Alexander; Blanch, Harvey W.; Wilke, Charles R.

    1981-08-01

    The production of ethanol from glucose by means of fermentation represents a potential long-range alternative to oil for use as a transportation fuel. Today's rising oil prices and the dwindling world supply of oil have made other fuels, such as ethanol, attractive alternatives. It has been shown that automobiles can operate, with minor alterations, on a 10% ethanol-gasoline mixture popularly known as gasohol. Wood has long been known as a potential source of glucose. Glucose may be obtained from wood following acid hydrolysis. In this research, it was found that saturating wood particles with HCl gas under pressure was an effective pretreatment before subjecting the wood to dilute acid hydrolysis. The pretreatment is necessary because of the tight lattice structure of cellulose, which inhibits dilute acid hydrolysis. HCl gas makes the cellulose more susceptible to hydrolysis and the glucose yield is doubled when dilute acid hydrolysis is preceded by HCl saturation at high pressure. The saturation was most effectively performed in a fluidized bed reactor, with pure HCl gas fluidizing equal volumes of ground wood and inert particles. The fluidized bed effectively dissipated the large amount of heat released upon HCl absorption into the wood. Batch reaction times of one hour at 314.7 p.s.i.a. gave glucose yields of 80% and xylose yields of 95% after dilute acid hydrolysis. A non-catalytic gas-solid reaction model, with gas diffusing through the solid limiting the reaction rate, was found to describe the HCl-wood reaction in the fluidized bed. HCl was found to form a stable adduct with the lignin residue in the wood, in a ratio of 3.33 moles per mole of lignin monomer. This resulted in a loss of 0.1453 lb. of HCl per pound of wood. The adduct was broken upon the addition of water. A process design and economic evaluation for a plant to produce 214 tons per day of glucose from air-dried ground Populus tristi gave an estimated glucose cost of 15.14 cents per pound. This

  17. High-Speed, High-Resolution Time-to-Digital Conversion

    NASA Technical Reports Server (NTRS)

    Katz, Richard; Kleyner, Igor; Garcia, Rafael

    2013-01-01

    This innovation is a series of time-tag pulses from a photomultiplier tube, featuring short time interval between pulses (e.g., 2.5 ns). Using the previous art, dead time between pulses is too long, or too much hardware is required, including a very-high-speed demultiplexer. A faster method is needed. The goal of this work is to provide circuits to time-tag pulses that arrive at a high rate using the hardwired logic in an FPGA - specifically the carry chain - to create what is (in effect) an analog delay line. High-speed pulses travel down the chain in a "wave." For instance, a pulse train has been demonstrated from a 1- GHz source reliably traveling down the carry chain. The size of the carry chain is over 10 ns in the time domain. Thus, multiple pulses will travel down the carry chain in a wave simultaneously. A register clocked by a low-skew clock takes a "snapshot" of the wave. Relatively simple logic can extract the pulses from the snapshot picture by detecting the transitions between logic states. The propagation delay of CMOS (complementary metal oxide semiconductor) logic circuits will differ and/or change as a result of temperature, voltage, age, radiation, and manufacturing variances. The time-to-digital conversion circuits can be calibrated with test signals, or the changes can be nulled by a separate on-die calibration channel, in a closed loop circuit.

  18. Fiber-Shaped Perovskite Solar Cells with High Power Conversion Efficiency.

    PubMed

    Qiu, Longbin; He, Sisi; Yang, Jiahua; Deng, Jue; Peng, Huisheng

    2016-05-01

    A perovskite solar cell fiber is created with a high power conversion efficiency of 7.1% through a controllable deposition method. A combination of aligned TiO2 nanotubes, a uniform perovskite layer, and transparent aligned carbon nanotube sheet contributes to the high photovoltaic performance. It is flexible and stable, and can be woven into smart clothes for wearable applications.

  19. Development of low read noise high conversion gain CMOS image sensor for photon counting level imaging

    NASA Astrophysics Data System (ADS)

    Seo, Min-Woong; Kawahito, Shoji; Kagawa, Keiichiro; Yasutomi, Keita

    2016-05-01

    A CMOS image sensor with deep sub-electron read noise and high pixel conversion gain has been developed. Its performance is recognized through image outputs from an area image sensor, confirming the capability of photoelectroncounting- level imaging. To achieve high conversion gain, the proposed pixel has special structures to reduce the parasitic capacitances around FD node. As a result, the pixel conversion gain is increased due to the optimized FD node capacitance, and the noise performance is also improved by removing two noise sources from power supply. For the first time, high contrast images from the reset-gate-less CMOS image sensor, with less than 0.3e- rms noise level, have been generated at an extremely low light level of a few electrons per pixel. In addition, the photon-counting capability of the developed CMOS imager is demonstrated by a measurement, photoelectron-counting histogram (PCH).

  20. Chromosomal double-strand breaks induce gene conversion at high frequency in mammalian cells.

    PubMed Central

    Taghian, D G; Nickoloff, J A

    1997-01-01

    Double-strand breaks (DSBs) stimulate chromosomal and extrachromosomal recombination and gene targeting. Transcription also stimulates spontaneous recombination by an unknown mechanism. We used Saccharomyces cerevisiae I-SceI to stimulate recombination between neo direct repeats in Chinese hamster ovary (CHO) cell chromosomal DNA. One neo allele was controlled by the dexamethasone-inducible mouse mammary tumor virus promoter and inactivated by an insertion containing an I-SceI site at which DSBs were introduced in vivo. The other neo allele lacked a promoter but carried 12 phenotypically silent single-base mutations that create restriction sites (restriction fragment length polymorphisms). This system allowed us to generate detailed conversion tract spectra for recipient alleles transcribed at high or low levels. Transient in vivo expression of I-SceI increased homologous recombination 2,000- to 10,000-fold, yielding recombinants at frequencies as high as 1%. Strikingly, 97% of these products arose by gene conversion. Most products had short, bidirectional conversion tracts, and in all cases, donor neo alleles (i.e., those not suffering a DSB) remained unchanged, indicating that conversion was fully nonreciprocal. DSBs in exogenous DNA are usually repaired by end joining requiring little or no homology or by nonconservative homologous recombination (single-strand annealing). In contrast, we show that chromosomal DSBs are efficiently repaired via conservative homologous recombination, principally gene conversion without associated crossing over. For DSB-induced events, similar recombination frequencies and conversion tract spectra were found under conditions of low and high transcription. Thus, transcription does not further stimulate DSB-induced recombination, nor does it appear to affect the mechanism(s) by which DSBs induce gene conversion. PMID:9343400

  1. Beyond ketonization: selective conversion of carboxylic acids to olefins over balanced Lewis acid-base pairs.

    PubMed

    Baylon, Rebecca A L; Sun, Junming; Martin, Kevin J; Venkitasubramanian, Padmesh; Wang, Yong

    2016-04-11

    We report the direct conversion of mixed carboxylic acids to C-C olefins with up to 60 mol% carbon yield through cascade (cross) ketonization, (cross) aldolization and self-deoxygenation reactions. Co-feeding hydrogen provides an additional ketone hydrogenation/dehydration pathway to a wider range of olefins.

  2. Senior English in Selected High Schools.

    ERIC Educational Resources Information Center

    Trammell, Robert Thomas

    In this study, 50 teachers of senior English were surveyed regarding their academic preparation and the English programs and curricular practices in their schools (18 selected high schools in Alabama). An analysis of existing professional literature was made to determine the status of current senior English programs and to ascertain what criteria…

  3. Designation of highly efficient catalysts for one pot conversion of glycerol to lactic acid

    PubMed Central

    Tao, Meilin; Dan Zhang; Guan, Hongyu; Huang, Guohui; Wang, Xiaohong

    2016-01-01

    Production of lactic acid from glycerol is a cascade catalytic procedure using multifunctional catalysts combined with oxidative and acidic catalytic sites. Therefore, a series of silver-exchanged phosphomolybdic acid catalysts (AgxH3−xPMo12O40, x = 1 ~ 3, abbreviated as AgxPMo) was designed and applied in glycerol oxidation with O2 as an oxidant to produce lactic acid (LA) without adding any base. Among all, total silver exchanged phosphomolybdic acid (Ag3PMo) was found to be the most active one with LA selectivity of 93% at 99% conversion under mild conditions of 5 h at 60 °C. The exceptionally high efficiency was contributed to the generation of strong Lewis acid sites, enhanced redox potentials and water-tolerance. More importantly, Ag3PMo was tolerant in crude glycerol from biodiesel production. And the reaction mechanism was also discussed. Meanwhile, Ag3PMo acted as a heterogeneous catalyst for 12 recycles without loss of activity. PMID:27431610

  4. Designation of highly efficient catalysts for one pot conversion of glycerol to lactic acid

    NASA Astrophysics Data System (ADS)

    Tao, Meilin; Dan Zhang; Guan, Hongyu; Huang, Guohui; Wang, Xiaohong

    2016-07-01

    Production of lactic acid from glycerol is a cascade catalytic procedure using multifunctional catalysts combined with oxidative and acidic catalytic sites. Therefore, a series of silver-exchanged phosphomolybdic acid catalysts (AgxH3‑xPMo12O40, x = 1 ~ 3, abbreviated as AgxPMo) was designed and applied in glycerol oxidation with O2 as an oxidant to produce lactic acid (LA) without adding any base. Among all, total silver exchanged phosphomolybdic acid (Ag3PMo) was found to be the most active one with LA selectivity of 93% at 99% conversion under mild conditions of 5 h at 60 °C. The exceptionally high efficiency was contributed to the generation of strong Lewis acid sites, enhanced redox potentials and water-tolerance. More importantly, Ag3PMo was tolerant in crude glycerol from biodiesel production. And the reaction mechanism was also discussed. Meanwhile, Ag3PMo acted as a heterogeneous catalyst for 12 recycles without loss of activity.

  5. Spontaneous peer conversation in preschoolers with high-functioning autism spectrum disorder versus typical development.

    PubMed

    Bauminger-Zviely, Nirit; Karin, Eynat; Kimhi, Yael; Agam-Ben-Artzi, Galit

    2014-04-01

    In typical development, early peer talk is crucial for pragmatic development. The pragmatic deficit, reflected in remarkably deficient conversational capabilities, is considered the hallmark of the language deficit in autism spectrum disorder (ASD); yet, spontaneous peer talk in preschoolers with ASD was rarely explored. We conducted comparative assessment of spontaneous peer talk during 10-min free-play scenarios in preschoolers with high-functioning ASD (HFASD; n = 27) versus those with typical development (n = 30). Groups were matched on SES, verbal/nonverbal MA, IQ, and CA. Correlations with CA, IQ, VMA, and NVMA were examined. We compared the two groups' interactions with a friend-partner versus a nonfriend partner; in addition, in the HFASD group, we examined interactions with a typical partner (mixed dyads) versus a partner with HFASD (nonmixed dyads). Children's conversations were videotaped and coded to tap pragmatic capabilities and conversational quality. Findings revealed group differences in pragmatic abilities and conversational quality, with the typical group showing more intact capacities than the HFASD group. However, in the HFASD group, interactions with friends surpassed interactions with nonfriends on several key pragmatic capabilities and on all conversational quality measures (meshing, assertiveness, and responsiveness), thus suggesting that friendship may enable children to converse in a more socially complex and coregulated way. Also, children with higher cognitive capabilities, especially in the HFASD group, demonstrated more intact pragmatic capacities. Despite the robust pragmatic deficit in HFASD, reflected in conversational capabilities, involvement in friendship relationships and high cognitive capabilities were linked to more intact pragmatic capacities. Theoretical and therapeutic implications are discussed. © 2013 The Authors. Journal of Child Psychology and Psychiatry. © 2013 Association for Child and Adolescent Mental Health.

  6. Conversion of methanol to hydrocarbons: how zeolite cavity and pore size controls product selectivity.

    PubMed

    Olsbye, Unni; Svelle, Stian; Bjørgen, Morten; Beato, Pablo; Janssens, Ton V W; Joensen, Finn; Bordiga, Silvia; Lillerud, Karl Petter

    2012-06-11

    Liquid hydrocarbon fuels play an essential part in the global energy chain, owing to their high energy density and easy transportability. Olefins play a similar role in the production of consumer goods. In a post-oil society, fuel and olefin production will rely on alternative carbon sources, such as biomass, coal, natural gas, and CO(2). The methanol-to-hydrocarbons (MTH) process is a key step in such routes, and can be tuned into production of gasoline-rich (methanol to gasoline; MTG) or olefin-rich (methanol to olefins; MTO) product mixtures by proper choice of catalyst and reaction conditions. This Review presents several commercial MTH projects that have recently been realized, and also fundamental research into the synthesis of microporous materials for the targeted variation of selectivity and lifetime of the catalysts.

  7. Fully Controllable Pancharatnam-Berry Metasurface Array with High Conversion Efficiency and Broad Bandwidth

    NASA Astrophysics Data System (ADS)

    Liu, Chuanbao; Bai, Yang; Zhao, Qian; Yang, Yihao; Chen, Hongsheng; Zhou, Ji; Qiao, Lijie

    2016-10-01

    Metasurfaces have powerful abilities to manipulate the properties of electromagnetic waves flexibly, especially the modulation of polarization state for both linearly polarized (LP) and circularly polarized (CP) waves. However, the transmission efficiency of cross-polarization conversion by a single-layer metasurface has a low theoretical upper limit of 25% and the bandwidth is usually narrow, which cannot be resolved by their simple additions. Here, we efficiently manipulate polarization coupling in multilayer metasurface to promote the transmission of cross-polarization by Fabry-Perot resonance, so that a high conversion coefficient of 80–90% of CP wave is achieved within a broad bandwidth in the metasurface with C-shaped scatters by theoretical calculation, numerical simulation and experiments. Further, fully controlling Pancharatnam-Berry phase enables to realize polarized beam splitter, which is demonstrated to produce abnormal transmission with high conversion efficiency and broad bandwidth.

  8. Fully Controllable Pancharatnam-Berry Metasurface Array with High Conversion Efficiency and Broad Bandwidth

    PubMed Central

    Liu, Chuanbao; Bai, Yang; Zhao, Qian; Yang, Yihao; Chen, Hongsheng; Zhou, Ji; Qiao, Lijie

    2016-01-01

    Metasurfaces have powerful abilities to manipulate the properties of electromagnetic waves flexibly, especially the modulation of polarization state for both linearly polarized (LP) and circularly polarized (CP) waves. However, the transmission efficiency of cross-polarization conversion by a single-layer metasurface has a low theoretical upper limit of 25% and the bandwidth is usually narrow, which cannot be resolved by their simple additions. Here, we efficiently manipulate polarization coupling in multilayer metasurface to promote the transmission of cross-polarization by Fabry-Perot resonance, so that a high conversion coefficient of 80–90% of CP wave is achieved within a broad bandwidth in the metasurface with C-shaped scatters by theoretical calculation, numerical simulation and experiments. Further, fully controlling Pancharatnam-Berry phase enables to realize polarized beam splitter, which is demonstrated to produce abnormal transmission with high conversion efficiency and broad bandwidth. PMID:27703254

  9. In operando spectroscopic studies of high temperature electrocatalysts used for energy conversion

    NASA Astrophysics Data System (ADS)

    McIntyre, Melissa Dawn

    Solid-state electrochemical cells are efficient energy conversion devices that can be used for clean energy production or for removing air pollutants from exhaust gas emitted by combustion processes. For example, solid oxide fuel cells generate electricity with low emissions from a variety of fuel sources; solid oxide electrolysis cells produce zero-emission H2 fuel; and solid-state DeNOx cells remove NOx gases from diesel exhaust. In order to maintain high conversion efficiencies, these systems typically operate at temperatures ≥ 500°C. The high operating temperatures, however, accelerate chemical and mechanical cell degradation. To improve device durability, a mechanistic understanding of the surface chemistry occurring at the cell electrodes (anode and cathode) is critical in terms of refining cell design, material selection and operation protocols. The studies presented herein utilized in operando Raman spectroscopy coupled with electrochemical measurements to directly correlate molecular/material changes with device performance in solid oxide cells under various operating conditions. Because excessive carbon accumulation with carbon-based fuels destroys anodes, the first three studies investigated strategies for mitigating carbon accumulation on Ni cermet anodes. Results from the first two studies showed that low amounts of solid carbon stabilized the electrical output and improved performance of solid oxide fuel cells operating with syn-gas (H 2/CO fuel mixture). The third study revealed that infiltrating anodes with Sn or BaO suppressed carbon accumulation with CH4 fuel and that H2O was the most effective reforming agent facilitating carbon removal. The last two studies explored how secondary phases formed in traditional solid oxide cell materials doped with metal oxides improve electrochemical performance. Results from the fourth study suggest that the mixed ion-electron conducting Zr5Ti7O24 secondary phase can expand the electrochemically active region

  10. Feature to space conversion during target selection in the dorsolateral and ventrolateral prefrontal cortex of monkeys.

    PubMed

    Inoue, Masato; Mikami, Akichika

    2010-03-01

    To investigate the neuronal mechanism of the process of selection of a target from an array of stimuli, we analysed neuronal activity of the lateral prefrontal cortex during the response period of a serial probe reproduction task. During the response period of this task, monkeys were trained to select a memorized target object from an array of three objects and make a saccadic eye movement toward it. Of 611 neurons, 74 neurons showed visual response and 56 neurons showed presaccadic activity during the response period. Among visual neurons, 27 showed array- and target-selectivity. All of these array- and target-selective visual responses were recorded from the ventrolateral prefrontal cortex (VLPFC). Among 56 neurons with presaccadic activity, nine showed target-selective activity, 17 showed target- and direction-selective activity, and 23 showed direction-selective activity. The target-selective, and the target- and direction-selective activities were recorded from the VLPFC, and the direction-selective activities were recorded from VLPFC and dorsolateral prefrontal cortex (DLPFC). The starting time of the activity was earlier for the target-selective, and target- and direction-selective activities in VLPFC, intermediate for the direction-selective activities in VLPFC, and later for the direction-selective activities in DLPFC. These results suggest that VLPFC plays a role in the process of selection of a target object from an array of stimuli, VLPFC and DLPFC play a role in determining the location of the target in space, and DLPFC plays a role in selecting a direction and making a decision to generate a saccadic eye movement.

  11. Beyond ketonization: selective conversion of carboxylic acids to olefins over balanced Lewis acid–base pairs

    SciTech Connect

    Baylon, Rebecca A. L.; Sun, Junming; Martin, Kevin J.; Venkitasubramanian, Padmesh; Wang, Yong

    2016-01-01

    Dwindling petroleum reserves combined with increased energy demand and political factors encouraging an increase in energy independence have led to a large amount of research on sustainable alternatives. To this end, biomass conversion has been recognized as themost readily viable technology to produce biofuel concerning our reliance on liquid fuels for transportation and has the advantage of being easily integrated into our heavy use of combustion engines. The interest in biomass conversion has also resulted in reduced costs and a greater abundance of bio-oil, a mixture of hundreds of oxygenates including alcohols, aldehydes, carboxylic acids, and ketones. However, the presence of carboxylic acids in bio-oil derived from lignocellulose pyrolysis leads to low pH, instability, and corrosiveness. In addition, carboxylic acids (i.e. acetic acid) can also be produced via fermentation of sugars. This can be accomplished by a variety of homoacetogenic microorganisms that can produce acetic acid with 100% carbon yield.

  12. Selective solvent absorption in coal conversion. Quarterly report, July 1, 1992--September 30, 1992

    SciTech Connect

    Larsen, J.W.; Amui, J.

    1992-12-31

    The objectives of this program include: Determine the importance of the presence of added hydrogen donor compounds within the coal in the first stage of direct liquefaction processes; and to determine the composition of the solvent absorbed by and present within the coal in the first stages of direct coal liquefaction. The scope includes the study of the conversion of Argonne Premium coals in tetralin and 2-t-butyltetralin and a comparison of the following: Conversion to soluble products and product composition. Hydrogen donated by both solvents will be measured by gas chromatography and the same technique will be used to establish the amount of dealkylation of 2-t-butyltetralin. Reactions will be performed at several different temperatures for varying amounts of time.

  13. Selective solvent absorption in coal conversion. Quarterly report, April 1, 1992--June 30, 1992

    SciTech Connect

    Larsen, J.W.; Amui, J.

    1992-06-01

    The objectives of this research are: (1) to determine the importance of the presence of added hydrogen donor compounds within the coal in the first stage of direct liquefaction processes; and (2) to determine the composition of the solvent absorbed by and present within the coal in the first stages of direct coal liquefaction. Scope of work study the conversion of Argonne Premium coals in tetralin and 2-t-butyltetralin and compare the following: conversion to soluble products and product composition. Hydrogen donated by both solvents will be measured by gas chromatography and the same technique will be used to establish the amount of dealkylation of 2-t-butyltetralin. Reactions will be performed at several different temperatures for varying amounts of time.

  14. Method for Selecting Appropriate Sentence from Documents on the WWW for the Open-ended Conversation Dialog System

    NASA Astrophysics Data System (ADS)

    Shibata, Masahiro; Tomiura, Yoichi; Nishiguchi, Tomomi

    We propose an open-ended dialog system that generates a proper sentence to a user's utterance using abundant documents on the World Wide Web as sources. Existing knowledge-based dialog systems give meaningful information to a user, but they are unsuitable for open-ended input. The system Eliza can handle open-ended input, but it gives no meaningful information. Our system lies between the above two dialog systems; it converses on various topics and gives meaningful information related to the user's utterances. The system selects an appropriate sentence as a response from documents gathered through the Web, on the basis of surface cohesion and shallow semantic coherence. The surface cohesion follows centering theory and the semantic coherence is calculated on the basis of the conditional distribution and inverse document frequency of content words (nouns, verbs, and adjectives.) We developed a trial system to converse about movies and experimentally found that the proposed method generated 66% appropriate responses.

  15. Restorative Justice Conferencing, Oral Language Competence, and Young Offenders: Are These High-Risk Conversations?

    ERIC Educational Resources Information Center

    Snow, Pamela

    2013-01-01

    This article is concerned with the oral language demands (both talking and listening) associated with restorative justice conferencing--an inherently highly verbal and conversational process. Many vulnerable young people (e.g., those in the youth justice system) have significant, yet unidentified language impairments, and these could compromise…

  16. Restorative Justice Conferencing, Oral Language Competence, and Young Offenders: Are These High-Risk Conversations?

    ERIC Educational Resources Information Center

    Snow, Pamela

    2013-01-01

    This article is concerned with the oral language demands (both talking and listening) associated with restorative justice conferencing--an inherently highly verbal and conversational process. Many vulnerable young people (e.g., those in the youth justice system) have significant, yet unidentified language impairments, and these could compromise…

  17. Stimulated backward Raman scattering excited in the picosecond range: high efficiency conversions

    NASA Astrophysics Data System (ADS)

    Chevalier, R.; Sokolovskaia, A.; Tcherniega, N.; Rivoire, G.

    1991-04-01

    Stimulated backward Raman scattering (SBRS) excited by picosecond laser pulses is produced with high efficiency conversion in materials displaying large Raman gain and small Kerr constants. A constant energy efficiency of 40% is obtained in aceton for a wide range of the exciting laser energy. The spatial, spectral and temporal structure of the backscattering beam is studied.

  18. Influence of Si distribution in framework of SAPO-34 and its particle size on propylene selectivity and production rate for conversion of ethylene to propylene.

    PubMed

    Iwase, Yasuyoshi; Motokura, Ken; Koyama, To-ru; Miyaji, Akimitsu; Baba, Toshihide

    2009-10-28

    To investigate the effect of SAPO-34 particle size (with a fixed Si mole fraction in its framework) and that of the Si mole fraction (in a SAPO-34 framework with fixed particle size) on propylene selectivity and production rate for the conversion of ethylene to propylene, SAPO-34 was prepared by hydrothermal synthesis using tetraethyl ammonium hydroxide or morpholine as a structural agent. The conversion of ethylene was carried out at 473 K using SAPO-34. The selectivity for propylene, the rate of propylene production, and the lifetime of the catalyst were strongly influenced by the catalyst crystal size. The SAPO-34 with a approximately 2.5 microm particle size had the highest selectivity for propylene (approximately 80%) up to a high conversion of ethylene (approximately 70%), while SAPO-34 with smaller particles had a longer catalyst lifetime, implying that catalyst deactivation was suppressed. The mole fraction of Si in the SAPO-34 framework with fixed particle size had little influence on the selectivity for propylene, indicating that the acid strength of SAPO-34 is independent of the Si mole fraction and all protons in SAPO-34 behave equivalently. Furthermore, the acid strength of protons determined by the measurements of NH(3)-TPD (temperature-programmed desorption) spectra did not depend on either the Si mole fraction or the SAPO-34 particle size. This result was also evident in the cracking rate of n-butane, which increased proportionally with increasing number of protons in SAPO-34.The number of protons generated by the incorporation of Si4+ into the SAPO-34 lattice increased proportionally, up to one Si atom introduced into every cage of SAPO-34, but did not continue to increase with further introduction of Si4+ into the lattice.

  19. High-efficiency continuous-wave Raman conversion with a BaWO(4) Raman crystal.

    PubMed

    Fan, Li; Fan, Ya-Xian; Li, Yu-Qiang; Zhang, Huaijin; Wang, Qin; Wang, Jin; Wang, Hui-Tian

    2009-06-01

    We report a high-efficiency cw Raman conversion with a BaWO(4) Raman crystal in a diode-end-pumped Nd:YVO(4) laser. The Raman threshold is as low as 3.6 W of diode power at 808 nm. The highest output power obtained at the 1,180 nm first-order Stokes line is 3.36 W under the diode power of 25.5 W, corresponding to a slope efficiency of 15.3% and a diode-to-Stokes optical conversion efficiency of 13.2%. The intracavity Raman conversion efficiency is 21.5% with respect to the available output of the 1,064 nm fundamental.

  20. High-efficiency wideband reflection polarization conversion metasurface for circularly polarized waves

    NASA Astrophysics Data System (ADS)

    Huang, Xiaojun; Chen, Jiao; Yang, Helin

    2017-07-01

    Metasurfaces have opened an effective way to handle the polarization states of electromagnetic waves due to their intrinsic parameters which could be flexibly tailored. In this paper, we present a simple anisotropic metasurface to realize the polarization manipulation of circularly polarized waves with high conversion efficiency in a wide frequency range. The presented simple metasurface can keep the handedness of the reflected waves for circularly polarized incident waves. Both the simulated and experimental results show that the bandwidth of the polarization conversion ratio more than 90% is 7.16 GHz (8.16-15.32 GHz), and the polarization extinction ratio is larger than 15 dB in this frequency range. Because of the simple design and easy fabrication, the designed metasurface can be an excellent candidate for reflection circular polarization conversion.

  1. Solar Selective Coatings for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Shumway, Dean A.

    2003-01-01

    Solar selective coatings are envisioned for use on minisatellites, for applications where solar energy is to be used to power heat engines or to provide thermal energy for remote regions in the interior of the spacecraft. These coatings are designed to have the combined properties of high solar absorptance and low infrared emittance. The coatings must be durable at elevated temperatures. For thermal bus applications, the temperature during operation is likely to be near 100 C. For heat engine applications. the temperature is expected to be much greater. The objective of this work was to screen candidate solar selective coatings for their high temperature durability. Candidate solar selective coatings were composed of molecular mixtures of metal and dielectric, including: nickel and aluminum oxide, titanium and aluminum oxide, and platinum and aluminum oxide. To identify high temperature durability, the solar absorptance and infrared emittance of the candidate coatings were evaluated initially, and after heating to temperatures in the range of 400 C to 700 C. The titanium and aluminum oxide molecular mixture was found to be the most durable.

  2. Influence of the nature and environment of manganese in Mn-BEA zeolites on NO conversion in selective catalytic reduction with ammonia.

    PubMed

    Baran, R; Valentin, L; Krafft, J-M; Grzybek, T; Glatzel, P; Dzwigaj, S

    2017-05-31

    Manganese-containing BEA zeolites, MnxSiBEA (x = 1-4 wt%) and Mn(I.E.)AlBEA, were prepared by a two-step post-synthesis method and a conventional wet ion-exchange, respectively, and applied as catalysts in the selective catalytic reduction of NO with ammonia (NH3-SCR). The physicochemical analysis of zeolite properties by high-energy-resolution fluorescence-detected XANES (HERFD-XANES) and X-ray emission spectroscopy (XES) uncovered that the coordination, geometry and oxidation state of Mn species are strongly related to the preparation method. Additionally, the study of catalyst acidity by FTIR spectroscopy with CO and pyridine probe molecules provided important insight into the number and type of acidic centres present on the catalyst surface. The catalytic results revealed that NO conversion depended on the state and content of Mn. The zeolites obtained by the two-step post-synthesis method and with a low Mn content were very active in the medium temperature range (NO conversion ∼100%) with simultaneous high selectivity to N2 due to the presence of isolated, framework Mn(iii) and Mn(ii) species. The N2O formation was especially high in the case of catalysts containing extra-framework polynuclear Mn species and negligible in the case of Mn(I.E.)AlBEA containing predominantly isolated, extra-framework Mn(ii) species.

  3. Development of a solar receiver for a high-efficiency thermionic/thermoelectric conversion system

    SciTech Connect

    Naito, H.; Kohsaka, Y.; Cooke, D.; Arashi, H.

    1996-10-01

    Solar energy is one of the most promising energy resources on Earth and in space, because it is clean and inexhaustible. Therefore, we have been developing a solar-powered high-efficiency thermionic-thermoelectric conversion system which combines a thermionic converter (TIC) with a thermoelectric converter (TEC) to use thermal energy efficiently and to achieve high efficiency conversion. The TIC emitter must uniformly heat up to 1800 K. The TIC emitter can be heated using thermal radiation from a solar receiver maintained at a high temperature by concentrated solar irradiation. A cylindrical cavity-type solar receiver constructed from graphite was designed and heated in a vacuum by using the solar concentrator at Tohoku University. The maximum temperature of the solar receiver enclosed by a molybdenum cup reached 1965 K, which was sufficiently high to heat a TIC emitter using thermal radiation from the receiver. 4 refs., 6 figs., 1 tab.

  4. Structural, down- and phase selective up-conversion emission properties of mixed valent Pr doped into oxides with tetravalent cations.

    PubMed

    Tiseanu, Carmen; Parvulescu, Vasile; Avram, Daniel; Cojocaru, Bogdan; Apostol, Nicoleta; Vela-Gonzalez, Andrea V; Sanchez-Dominguez, Margarita

    2014-03-28

    We report on structure-property relationships in Pr-doped CeO2 and ZrO2 using X-ray diffraction (XRD), Raman, UV to Vis Diffuse Reflectance (DR-UV/Vis), X-ray Photoelectron (XPS), and luminescence (PL) spectroscopies. Both 3+ and 4+ valence states of Pr are evidenced, irrespective of the host and calcination temperature, T (T = 500 and 1000 °C) with consequences on absorption, surface, vibrational and luminescence properties. Only zirconia represents a suitable host for Pr(3+) luminescence. The distinct trivalent Pr centers and their excitation mechanism are identified in relation to the tetragonal and monoclinic phases of ZrO2. A near-infrared to visible up-conversion (UPC) emission of Pr(3+) is observed upon excitation at 959 nm which occurs, most probably, via a two-photon excited state process. By using a multi-wavelength, time-gated excitation, the UPC process is established as phase selective, i.e. only Pr(3+) located in the monoclinic sites of the mixed phase, monoclinic and tetragonal ZrO2 (T = 1000 °C) contribute to the UPC emission. We believe that, besides the local symmetry, a key role in phase selective UPC is played by the presence of Pr(3+) low-lying 4f 5d levels. To the best of our knowledge, this is the first report of phase selective up-conversion emission in a lanthanide doped multi-phase host.

  5. Genetic improvement of feed conversion ratio via indirect selection against lipid deposition in farmed rainbow trout (Oncorhynchus mykiss Walbaum).

    PubMed

    Kause, Antti; Kiessling, Anders; Martin, Samuel A M; Houlihan, Dominic; Ruohonen, Kari

    2016-11-01

    In farmed fish, selective breeding for feed conversion ratio (FCR) may be possible via indirectly selecting for easily-measured indicator traits correlated with FCR. We tested the hypothesis that rainbow trout with low lipid% have genetically better FCR, and that lipid% may be genetically related to retention efficiency of macronutrients, making lipid% a useful indicator trait. A quantitative genetic analysis was used to quantify the benefit of replacing feed intake in a selection index with one of three lipid traits: body lipid%, muscle lipid% or viscera% weight of total body weight (reflecting visceral lipid). The index theory calculations showed that simultaneous selection for weight gain and against feed intake (direct selection to improve FCR) increased the expected genetic response in FCR by 1·50-fold compared with the sole selection for growth. Replacing feed intake in the selection index with body lipid%, muscle lipid% or viscera% increased genetic response in FCR by 1·29-, 1·49- and 1·02-fold, respectively, compared with the sole selection for growth. Consequently, indirect selection for weight gain and against muscle lipid% was almost as effective as direct selection for FCR. Fish with genetically low body and muscle lipid% were more efficient in turning ingested protein into protein weight gain. Both physiological and genetic mechanisms promote the hypothesis that low-lipid% fish are more efficient. These results highlight that in breeding programmes of rainbow trout, control of lipid deposition improves not only FCR but also protein-retention efficiency. This improves resource efficiency of aquaculture and reduces nutrient load to the environment.

  6. Efficiency of frequency conversion of high power laser and KDP crystal clamping method

    NASA Astrophysics Data System (ADS)

    Yan, Han; Du, Weifeng; Pei, Guoqing; Qin, Tinghai; Ye, Lang; Xu, Xu

    2017-05-01

    In the high power solid laser driver, the frequency conversion unit is of strict requirement to meet the drive condition of ICF. The performance of large caliber KDP crystal, which is the core of frequency conversion of laser, is a vital aspect affecting the overall technical index of the laser driver. In order to get a higher efficiency of frequency conversion, KDP crystal must keep a better surface condition, which asks for high-quality assemblage and adjustment. The current method used in engineering has insufficient knowledge and recognition on surface deformation control of the crystal. Meanwhile, the method itself is of low efficiency on clamping, and lacks of protection for the crystal. Thus, in this article an investigation of crystal clamping method with lower force was performed, factors affecting the surface of crystal were explored, through both imitation and experiment. The clamping method was redesigned and the frequency conversion efficiency was tested. Meanwhile, with the new method, clamping efficiency increases, the optical performance of crystals improves, and the crystals get better protection.

  7. Low-temperature conversion of high-moisture biomass: Continuous reactor system results

    NASA Astrophysics Data System (ADS)

    Elliott, D. C.; Sealock, L. J., Jr.; Butner, R. S.; Baker, E. G.; Neuenschwander, G. G.

    1989-10-01

    Pacific Northwest Laboratory (PNL) is developing a low temperature, catalytic process for converting high moisture biomass feedstocks and other wet organic substances to useful gaseous fuels. This system, in which thermocatalytic conversion takes place in an aqueous environment, was designed to overcome the problems usually encountered with high water content feedstocks. The process uses a reduced nickel catalyst at temperatures as low as 350 C and pressures ranging from 2000 to 4000 psig; conditions favoring the formation of gas consisting mostly of methane. The results of numerous batch tests showed that the system could convert feedstocks not readily converted by conventional methods. Fifteen tests were conducted in a continuous reactor system to further evaluate the effectiveness of the process for high moisture biomass gasification and to obtain conversion rate data needed for process scaleup. During the tests, the complex gasification reactions were evaluated by several analytical methods. The results of these tests show that the heating value of the gas ranged from 400 to 500 Btu/scf, and if the carbon dioxide is removed, the product gas is pipeline quality. Conversion of the feedstocks was high. Engineering analysis indicates that, based on these results, a tubular reactor can be designed that should convert greater than 99 percent of the carbon fed as high moisture biomass to a gaseous product in a reaction time of less than 11 min.

  8. Low-temperature conversion of high-moisture biomass: Continuous reactor system results

    SciTech Connect

    Elliott, D.C.; Sealock, L.J. Jr.; Butner, R.S.; Baker, E.G.; Neuenschwander, G.G.

    1989-10-01

    Pacific Northwest Laboratory (PNL) is developing a low-temperature, catalytic process for converting high-moisture biomass feedstocks and other wet organic substances to useful gaseous fuels. This system, in which thermocatalytic conversion takes place in an aqueous environment, was designed to overcome the problems usually encountered with high-water-content feedstocks. The process uses a reduced nickel catalyst at temperatures as low as 350{degree}C and pressures ranging from 2000 to 4000 psig -- conditions favoring the formation of gas consisting mostly of methane. The results of numerous batch tests showed that the system could convert feedstocks not readily converted by conventional methods. Fifteen tests were conducted in a continuous reactor system to further evaluate the effectiveness of the process for high-moisture biomass gasification and to obtain conversion rate data needed for process scaleup. During the tests, the complex gasification reactions were evaluated by several analytical methods. The results of these tests show that the heating value of the gas ranged from 400 to 500 Btu/scf, and if the carbon dioxide is removed, the product gas is pipeline quality. Conversion of the feedstocks was high. Engineering analysis indicates that, based on these results, a tubular reactor can be designed that should convert greater than 99% of the carbon fed as high-moisture biomass to a gaseous product in a reaction time of less than 11 min.

  9. High-Molecular Compounds (Selected Articles).

    DTIC Science & Technology

    1987-10-30

    34 07 250 HIGH-MOLECULAR COMPOUNIDS (SELECTED ARTICLES)(U) FOREIGN Il TECNOLOGY DIV WIGT-PATTERtSON RFD ON 30 OCT 6? FTD-ID(RS)T- M 2-97 UNCLASSIFIED...one can see, Is quite small and corresponds to such low mobility of molecules, at which the NMR signal is not observed. 5 , - Introduction of...system, which is represented by curve 4 (Fig. 2), located near the axis of the ordinate. The mobility of molecules with this degree of plastification

  10. Synthesis of high-silica offretite by the interzeolite conversion method

    SciTech Connect

    Itakura, Masaya; Oumi, Yasunori; Sadakane, Masahiro; Sano, Tsuneji

    2010-05-15

    High-silica offretite (Si/Al = 7.6-8.0) with no or very little amount of erionite was successfully obtained by the interzeolite conversion of faujasite used as a starting material in the presence of both benzyltrimethylammonium hydroxide and the structure-forming alkali metal cations such as Li{sup +} and Na{sup +}. Hydrothermal conversion of faujasite into offretite depended on the Si/Al ratio of the starting faujasite. Only faujasite with Si/Al ratio of 16-31 was converted into offretite. In this conversion, offretite was obtained in 1 day, indicating that the crystallization rate was enhanced by using faujasite as the starting material. Based on {sup 13}C CP/MAS NMR measurements, most of benzyltrimethylammonium cations were presented intact within zeolitic pores of the obtained offretite. As offretite was not obtained from amorphous materials (amorphous SiO{sub 2} and {gamma}-Al{sub 2}O{sub 3} or Al(OH){sub 3}), the advantage of the interzeolite conversion was demonstrated.

  11. Conversion of bromine during thermal decomposition of printed circuit boards at high temperature.

    PubMed

    Jin, Yu-qi; Tao, Lin; Chi, Yong; Yan, Jian-hua

    2011-02-15

    The conversion of bromine during the thermal decomposition of printed circuit boards (PCBs) was investigated at isothermal temperatures ranging from 800°C to 1100°C by using a quartz tube furnace. The influence of temperature, oxygen concentrations (0%, 10% and 21% in the nitrogen-oxygen atmosphere) and content of steam on conversion of bromine was studied. With the increment of temperature, the conversion from organic bromine in the PCBs to inorganic bromine in the gaseous fraction increased from 69.0% to 96.4%. The bromine was mainly evolved as HBr and Br(2) in oxidizing condition and the Br(2)/HBr mass ratio increased at stronger oxidizing atmosphere. The experimental results also indicated that the existence of steam can reduce the formation of Br(2). Furthermore, co-combustion of PCBs with S and CaO, both as addition agents, was investigated, respectively. In the presence of SO(2), Br(2)/HBr mass ratio obviously decreased. Moreover, the utilization of calcium oxide can efficiently promote the conversion of organic bromine to inorganic bromine. According to the experimental results, incinerating PCBs at high temperature can efficiently destroy the organobrominated compounds that are considered to be possible precursors of polybrominated dibenzeo-p-dioxins and dibenzofurans (PBDD/Fs), but the Br(2) and HBr in flue gas should be efficiently controlled.

  12. Efficient and high speed depth-based 2D to 3D video conversion

    NASA Astrophysics Data System (ADS)

    Somaiya, Amisha Himanshu; Kulkarni, Ramesh K.

    2013-09-01

    Stereoscopic video is the new era in video viewing and has wide applications such as medicine, satellite imaging and 3D Television. Such stereo content can be generated directly using S3D cameras. However, this approach requires expensive setup and hence converting monoscopic content to S3D becomes a viable approach. This paper proposes a depth-based algorithm for monoscopic to stereoscopic video conversion by using the y axis co-ordinates of the bottom-most pixels of foreground objects. This code can be used for arbitrary videos without prior database training. It does not face the limitations of single monocular depth cues nor does it combine depth cues, thus consuming less processing time without affecting the efficiency of the 3D video output. The algorithm, though not comparable to real-time, is faster than the other available 2D to 3D video conversion techniques in the average ratio of 1:8 to 1:20, essentially qualifying as high-speed. It is an automatic conversion scheme, hence directly gives the 3D video output without human intervention and with the above mentioned features becomes an ideal choice for efficient monoscopic to stereoscopic video conversion. [Figure not available: see fulltext.

  13. Highly Efficient Near Infrared Photothermal Conversion Properties of Reduced Tungsten Oxide/Polyurethane Nanocomposites

    PubMed Central

    Chala, Tolesa Fita; Wu, Chang-Mou; Chou, Min-Hui; Gebeyehu, Molla Bahiru; Cheng, Kuo-Bing

    2017-01-01

    In this work, novel WO3-x/polyurethane (PU) nanocomposites were prepared by ball milling followed by stirring using a planetary mixer/de-aerator. The effects of phase transformation (WO3 → WO2.8 → WO2.72) and different weight fractions of tungsten oxide on the optical performance, photothermal conversion, and thermal properties of the prepared nanocomposites were examined. It was found that the nanocomposites exhibited strong photoabsorption in the entire near-infrared (NIR) region of 780–2500 nm and excellent photothermal conversion properties. This is because the particle size of WO3-x was greatly reduced by ball milling and they were well-dispersed in the polyurethane matrix. The higher concentration of oxygen vacancies in WO3-x contribute to the efficient absorption of NIR light and its conversion into thermal energy. In particular, WO2.72/PU nanocomposites showed strong NIR light absorption of ca. 92%, high photothermal conversion, and better thermal conductivity and absorptivity than other WO3/PU nanocomposites. Furthermore, when the nanocomposite with 7 wt % concentration of WO2.72 nanoparticles was irradiated with infrared light, the temperature of the nanocomposite increased rapidly and stabilized at 120 °C after 5 min. This temperature is 52 °C higher than that achieved by pure PU. These nanocomposites are suitable functional materials for solar collectors, smart coatings, and energy-saving applications. PMID:28737689

  14. Carbon Dioxide Conversion to Methanol over Size-Selected Cu 4 Clusters at Low Pressures

    SciTech Connect

    Liu, Cong; Yang, Bing; Tyo, Eric; Seifert, Soenke; DeBartolo, Janae; von Issendorff, Bernd; Zapol, Peter; Vajda, Stefan; Curtiss, Larry A.

    2015-06-26

    In order to utilize the captured CO2, the activation of CO2 and its hydrogenation to methanol are of much interest . We investigate the use of size-selected Cu-4 clusters supported on Al2O3 thin films for CO2 reduction in the presence of hydrogen. The catalytic activity was measured under near-atmospheric reaction conditions with a low CO2 partial pressure, and the oxidation state of the clusters was investigated by in situ grazing incidence X-ray absorption spectroscopy. The results indicate that size-selected Cu-4 clusters are the most active low-pressure catalyst for catalytic CO2 conversion to CH3OH. Density functional theory calculations reveal that Cu-4 clusters have a low activation barrier for conversion of CO2 to CH3OH. Our study suggests that small Cu clusters may be excellent and efficient catalysts for the recycling of released CO2.

  15. Partial oxidative conversion of methane to methanol through selective inhibition of methanol dehydrogenase in methanotrophic consortium from landfill cover soil.

    PubMed

    Han, Ji-Sun; Ahn, Chang-Min; Mahanty, Biswanath; Kim, Chang-Gyun

    2013-11-01

    Using a methanotrophic consortium (that includes Methylosinus sporium NCIMB 11126, Methylosinus trichosporium OB3b, and Methylococcus capsulatus Bath) isolated from a landfill site, the potential for partial oxidation of methane into methanol through selective inhibition of methanol dehydrogenase (MDH) over soluble methane monooxygenase (sMMO) with some selected MDH inhibitors at varied concentration range, was evaluated in batch serum bottle and bioreactor experiments. Our result suggests that MDH activity could effectively be inhibited either at 40 mM of phosphate, 100 mM of NaCl, 40 mM of NH4Cl or 50 μM of EDTA with conversion ratios (moles of CH3OH produced per mole CH4 consumed) of 58, 80, 80, and 43 %, respectively. The difference between extent of inhibition in MDH activity and sMMO activity was significantly correlated (n = 6, p < 0.05) with resultant methane to methanol conversion ratio. In bioreactor study with 100 mM of NaCl, a maximum specific methanol production rate of 9 μmol/mg h was detected. A further insight with qPCR analysis of MDH and sMMO coding genes revealed that the gene copy number continued to increase along with biomass during reactor operation irrespective of presence or absence of inhibitor, and differential inhibition among two enzymes was rather the key for methanol production.

  16. Low-temperature conversion of high-moisture biomass: Topical report, January 1984--January 1988

    SciTech Connect

    Sealock, L.J. Jr.; Elliott, D.C.; Butner, R.S.; Neuenschwander, G.G.

    1988-10-01

    Pacific Northwest Laboratory (PNL) is developing a low-temperature, catalytic process that converts high-moisture biomass feedstocks and other wet organic substances to useful gaseous and liquid fuels. The advantage of this process is that it works without the need for drying or dewatering the feedstock. Conventional thermal gasification processes, which require temperatures above 750/degree/C and air or oxygen for combustion to supply reaction heat, generally cannot utilize feedstocks with moisture contents above 50 wt %, as the conversion efficiency is greatly reduced as a result of the drying step. For this reason, anaerobic digestion or other bioconversion processes traditionally have been used for gasification of high-moisture feedstocks. However, these processes suffer from slow reaction rates and incomplete carbon conversion. 50 refs., 21 figs., 22 tabs.

  17. A low complexity, low spur digital IF conversion circuit for high-fidelity GNSS signal playback

    NASA Astrophysics Data System (ADS)

    Su, Fei; Ying, Rendong

    2016-01-01

    A low complexity high efficiency and low spur digital intermediate frequency (IF) conversion circuit is discussed in the paper. This circuit is key element in high-fidelity GNSS signal playback instrument. We analyze the spur performance of a finite state machine (FSM) based numerically controlled oscillators (NCO), by optimization of the control algorithm, a FSM based NCO with 3 quantization stage can achieves 65dB SFDR in the range of the seventh harmonic. Compare with traditional lookup table based NCO design with the same Spurious Free Dynamic Range (SFDR) performance, the logic resource require to implemented the NCO is reduced to 1/3. The proposed design method can be extended to the IF conversion system with good SFDR in the range of higher harmonic components by increasing the quantization stage.

  18. Catalyst for selective conversion of synthesis gas and method of making the catalyst

    DOEpatents

    Dyer, Paul N.; Pierantozzi, Ronald

    1986-01-01

    A Fischer-Tropsch (F-T) catalyst, a method of making the catalyst and an F-T process utilizing the catalyst by which synthesis gas, particularly carbon-monoxide rich synthesis gas is selectively converted to higher hydrocarbons of relatively narrow carbon number range. In general, the selective and notably stable catalyst, consists of an inert carrier first treated with a Group IV B metal compound (such as zirconium or titanium), preferably an alkoxide compound, and subsequently treated with an organic compound of an F-T metal catalyst, such as cobalt, iron or ruthenium carbonyl. Reactions with air and water and calcination are specifically avoided in the catalyst preparation procedure.

  19. Color-conversion efficiency enhancement of quantum dots via selective area nano-rods light-emitting diodes.

    PubMed

    Liu, Che-Yu; Chen, Tzu-Pei; Kao, Tsung Sheng; Huang, Jhih-Kai; Kuo, Hao-Chung; Chen, Yang-Fang; Chang, Chun-Yen

    2016-08-22

    A large enhancement of color-conversion efficiency of colloidal quantum dots in light-emitting diodes (LEDs) with novel structures of nanorods embedded in microholes has been demonstrated. Via the integration of nano-imprint and photolithography technologies, nanorods structures can be fabricated at specific locations, generating functional nanostructured LEDs for high-efficiency performance. With the novel structured LED, the color-conversion efficiency of the existing quantum dots can be enhanced by up to 32.4%. The underlying mechanisms can be attributed to the enhanced light extraction and non-radiative energy transfer, characterized by conducting a series of electroluminescence and time-resolved photoluminescence measurements. This hybrid nanostructured device therefore exhibits a great potential for the application of multi-color lighting sources.

  20. Patterns in Student Perceptions of Start-Up and Conversion Small High Schools

    ERIC Educational Resources Information Center

    Feldman, Jay; O'Dwyer, Anne

    2010-01-01

    Schools created as part of the small schools movement have been in operation for almost a decade, allowing identification of patterns in their growth. This study examines 4 years of survey data on 12 start-up and 13 conversion small high schools. Start-up small schools, almost all of which began with one grade level and grew by one grade per year,…

  1. Patterns in Student Perceptions of Start-Up and Conversion Small High Schools

    ERIC Educational Resources Information Center

    Feldman, Jay; O'Dwyer, Anne

    2010-01-01

    Schools created as part of the small schools movement have been in operation for almost a decade, allowing identification of patterns in their growth. This study examines 4 years of survey data on 12 start-up and 13 conversion small high schools. Start-up small schools, almost all of which began with one grade level and grew by one grade per year,…

  2. Interpersonal Movement Synchrony Responds to High- and Low-Level Conversational Constraints

    PubMed Central

    Paxton, Alexandra; Dale, Rick

    2017-01-01

    Much work on communication and joint action conceptualizes interaction as a dynamical system. Under this view, dynamic properties of interaction should be shaped by the context in which the interaction is taking place. Here we explore interpersonal movement coordination or synchrony—the degree to which individuals move in similar ways over time—as one such context-sensitive property. Studies of coordination have typically investigated how these dynamics are influenced by either high-level constraints (i.e., slow-changing factors) or low-level constraints (i.e., fast-changing factors like movement). Focusing on nonverbal communication behaviors during naturalistic conversation, we analyzed how interacting participants' head movement dynamics were shaped simultaneously by high-level constraints (i.e., conversation type; friendly conversations vs. arguments) and low-level constraints (i.e., perceptual stimuli; non-informative visual stimuli vs. informative visual stimuli). We found that high- and low-level constraints interacted non-additively to affect interpersonal movement dynamics, highlighting the context sensitivity of interaction and supporting the view of joint action as a complex adaptive system. PMID:28804466

  3. Freestanding and flexible graphene papers as bioelectrochemical cathode for selective and efficient CO2 conversion.

    PubMed

    Aryal, Nabin; Halder, Arnab; Zhang, Minwei; Whelan, Patrick R; Tremblay, Pier-Luc; Chi, Qijin; Zhang, Tian

    2017-08-22

    During microbial electrosynthesis (MES) driven CO2 reduction, cathode plays a vital role by donating electrons to microbe. Here, we exploited the advantage of reduced graphene oxide (RGO) paper as novel cathode material to enhance electron transfer between the cathode and microbe, which in turn facilitated CO2 reduction. The acetate production rate of Sporomusa ovata-driven MES reactors was 168.5 ± 22.4 mmol m(-2) d(-1) with RGO paper cathodes poised at -690 mV versus standard hydrogen electrode. This rate was approximately 8 fold faster than for carbon paper electrodes of the same dimension. The current density with RGO paper cathodes of 2580 ± 540 mA m(-2) was increased 7 fold compared to carbon paper cathodes. This also corresponded to a better cathodic current response on their cyclic voltammetric curves. The coulombic efficiency for the electrons conversion into acetate was 90.7 ± 9.3% with RGO paper cathodes and 83.8 ± 4.2% with carbon paper cathodes, respectively. Furthermore, more intensive cell attachment was observed on RGO paper electrodes than on carbon paper electrodes with confocal laser scanning microscopy and scanning electron microscopy. These results highlight the potential of RGO paper as a promising cathode for MES from CO2.

  4. Selective conversion by microglia of dehydroepiandrosterone to 5-androstenediol-A steroid with inherent estrogenic properties.

    PubMed

    Jellinck, Peter H; Kaufmann, Martin; Gottfried-Blackmore, Andres; McEwen, Bruce S; Jones, Glenville; Bulloch, Karen

    2007-01-01

    The well-established neuroprotective effect of dehydroepiandrosterone (DHEA) has been attributed to its metabolism in the brain to provide estrogens known to be neuroprotective and to enhance memory and learning in humans and animals. However, our previous work showed that the conversion of DHEA to 4-androstenedione (AD), the precursor of estrone (E(1)) and estradiol (E(2)), is very low in several different types of neural cells, and that the main product is 7alpha-hydroxy-DHEA (7alpha-OH-DHEA). In this study, we found that microglia are an exception and produce mainly 5-androstene-3beta,17beta-diol (Delta(5)-Adiol), a C(19) steroid with estrogen-like activity from DHEA. Virtually, no other products, including testosterone (T) were detected by TLC or HPLC in incubations of (3)H-labeled DHEA with the BV2 microglial cell line. Microglia are important brain cells that are thought to play a house-keeping role during the steady state, and that are crucial to the brain's immune reaction to injury and the healing process. Our findings suggest that the microglia-produced Delta(5)-Adiol might have a role in modulating estrogen-sensitive neuroplastic events in the brain, in the absence of adequate local synthesis of estrone and estradiol.

  5. Size dependent stability of cobalt nanoparticles on silica under high conversion Fischer-Tropsch environment.

    PubMed

    Wolf, Moritz; Kotzé, Hendrik; Fischer, Nico; Claeys, Michael

    2017-02-15

    Highly monodisperse cobalt crystallites, supported on Stöber silica spheres, as model catalysts for the Fischer-Tropsch synthesis were exposed to simulated high conversion environments in the presence and absence of CO utilising an in house developed in situ magnetometer. The catalyst comprising the smallest crystallites in the metallic state (average diameter of 3.2 nm) experienced pronounced oxidation whilst the ratio of H2O to H2 was increased stepwise to simulate CO conversions from 26% up to complete conversion. Direct exposure of this freshly reduced catalyst to a high conversion Fischer-Tropsch environment resulted in almost spontaneous oxidation of 40% of the metallic cobalt. In contrast, a model catalyst with cobalt crystallites of 5.3 nm only oxidised to a small extent even when exposed to a simulated conversion of over 99%. The largest cobalt crystallites were rather stable and only experienced measurable oxidation when subjected to H2O in the absence of H2. This size dependency of the stability is in qualitative accordance with reported thermodynamic calculations. However, the cobalt crystallites showed an unexpected low susceptibility to oxidation, i.e. only relatively high ratios of H2O to H2 partial pressure caused oxidation. Similar experiments in the presence of CO revealed the significance of the actual Fischer-Tropsch synthesis on the metallic surface as the dissociation of CO, an elementary step in the Fischer-Tropsch mechanism, was shown to be a prerequisite for oxidation. Direct oxidation of cobalt to CoO by H2O seems to be kinetically hindered. Thus, H2O may only be capable of indirect oxidation, i.e. high concentrations prevent the removal of adsorbed oxygen species on the cobalt surface leading to oxidation. However, a spontaneous direct oxidation of cobalt at the interface between the support and the crystallites by H2O forming presumably cobalt silicate type species was observed in the presence and absence of CO. The formation of these

  6. All-optical phase modulated format conversion for high transmission rates based on fiber nonlinearity

    NASA Astrophysics Data System (ADS)

    Duarte, Vanessa C.; Drummond, Miguel V.; Nogueira, Rogério N.

    2013-11-01

    Advanced modulation formats are an emerging area since they allow reducing the symbol rate while encoding more bits per symbol. This allows higher spectral efficiencies. In addition, we can achieve higher data rates using lower-speed equipment like in all-optical format conversion systems, an important step for the development of systems with high transmission rates. In this paper we study the impact of some impairments found in all-optical advanced format conversions based on cross phase modulation (XPM) on a highly nonlinear fiber (HNLF), such as amplified spontaneous emission (ASE), nonlinear fiber length and group velocity dispersion (GVD), and analyze its performance based on error vector magnitude (EVM) for different bitrate transmissions. This simulation study is applied on earlier proposed phase modulated format conversion where n nonreturn-to-zero on-off keying (NRZ-OOK) channels at 10 Gb/s are converted into a return-to-zero m phase shift keying (RZ-mPSK) at 20Gb/s. We extend the work with simulations and show the results for n NRZ-OOK channels at 20Gb/s, 40 Gb/s and 50Gb/s to RZ-PSK at 40Gb/s, 80 Gb/s and 100Gb/s, respectively.

  7. High-Efficiency Photovoltaic Energy Conversion using Surface Acoustic Waves in Piezoelectric Semiconductors

    NASA Astrophysics Data System (ADS)

    Yakovenko, Victor

    2010-03-01

    We propose a radically new design for photovoltaic energy conversion using surface acoustic waves (SAWs) in piezoelectric semiconductors. The periodically modulated electric field from SAW spatially separates photogenerated electrons and holes to the maxima and minima of SAW, thus preventing their recombination. The segregated electrons and holes are transported by the moving SAW to the collecting electrodes of two types, which produce dc electric output. Recent experiments [1] using SAWs in GaAs have demonstrated the photon to current conversion efficiency of 85%. These experiments were designed for photon counting, but we propose to adapt these techniques for highly efficient photovoltaic energy conversion. The advantages are that the electron-hole segregation takes place in the whole volume where SAW is present, and the electrons and holes are transported in the organized, collective manner at high speed, as opposed to random diffusion in conventional devices.[4pt] [1] S. J. Jiao, P. D. Batista, K. Biermann, R. Hey, and P. V. Santos, J. Appl. Phys. 106, 053708 (2009).

  8. Rationale for continuing R&D in direct coal conversion to produce high quality transportation fuels

    SciTech Connect

    Srivastava, R.D.; McIlvried, H.G.; Gray, D.

    1995-12-31

    For the foreseeable future, liquid hydrocarbon fuels will play a significant role in the transportation sector of both the United States and the world. Factors favoring these fuels include convenience, high energy density, and the vast existing infrastructure for their production and use. At present the U.S. consumes about 26% of the world supply of petroleum, but this situation is expected to change because of declining domestic production and increasing competition for imports from countries with developing economies. A scenario and time frame are developed in which declining world resources will generate a shortfall in petroleum supply that can be allieviated in part by utilizing the abundant domestic coal resource base. One option is direct coal conversion to liquid transportation fuels. Continued R&D in coal conversion technology will results in improved technical readiness that can significantly reduce costs so that synfuels can compete economically in a time frame to address the shortfall.

  9. Biodiesel production from algae oil high in free fatty acids by two-step catalytic conversion.

    PubMed

    Chen, Lin; Liu, Tianzhong; Zhang, Wei; Chen, Xiaolin; Wang, Junfeng

    2012-05-01

    The effect of storage temperature and time on lipid composition of Scenedesmus sp. was studied. When stored at 4°C or higher, the free fatty acid content in the wet biomass increased from a trace to 62.0% by day 4. Using two-step catalytic conversion, algae oil with a high free fatty acid content was converted to biodiesel by pre-esterification and transesterification. The conversion rate of triacylglycerols reached 100% under the methanol to oil molar ratio of 12:1 during catalysis with 2% potassium hydroxide at 65°C for 30 min. This process was scaled up to produce biodiesel from Scenedesmus sp. and Nannochloropsis sp. oil. The crude biodiesel was purified using bleaching earth. Except for moisture content, the biodiesel conformed to Chinese National Standards.

  10. Selective aerobic alcohol oxidation method for conversion of lignin into simple aromatic compounds

    DOEpatents

    Stahl, Shannon S; Rahimi, Alireza

    2015-03-03

    Described is a method to oxidize lignin or lignin sub-units. The method includes oxidation of secondary benzylic alcohol in the lignin or lignin sub-unit to a corresponding ketone in the presence of unprotected primarily aliphatic alcohol in the lignin or lignin sub-unit. The optimal catalyst system consists of HNO.sub.3 in combination with another Bronsted acid, in the absence of a metal-containing catalyst, thereby yielding a selectively oxidized lignin or lignin sub-unit. The method may be carried out in the presence or absence of additional reagents including TEMPO and TEMPO derivatives.

  11. Medium Bandgap Conjugated Polymer for High Performance Polymer Solar Cells Exceeding 9% Power Conversion Efficiency.

    PubMed

    Jung, Jae Woong; Liu, Feng; Russell, Thomas P; Jo, Won Ho

    2015-12-02

    Two medium-bandgap polymers composed of benzo[1,2-b:4,5-b']dithiohpene and 2,1,3-benzothiadiazole with 6-octyl-thieno[3,2-b]thiophene as a π-bridge unit are synthesized and their photovoltaic properties are analyzed. The two polymers have deep highest occupied molecular orbital energy levels, high crystallinity, optimal bulk-heterojunction morphology, and efficient charge transport, resulting in a power conversion efficiency of as high as 9.44% for a single-junction polymer solar-cell device. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. A semi-automatic 2D-to-3D video conversion with adaptive key-frame selection

    NASA Astrophysics Data System (ADS)

    Ju, Kuanyu; Xiong, Hongkai

    2014-11-01

    To compensate the deficit of 3D content, 2D to 3D video conversion (2D-to-3D) has recently attracted more attention from both industrial and academic communities. The semi-automatic 2D-to-3D conversion which estimates corresponding depth of non-key-frames through key-frames is more desirable owing to its advantage of balancing labor cost and 3D effects. The location of key-frames plays a role on quality of depth propagation. This paper proposes a semi-automatic 2D-to-3D scheme with adaptive key-frame selection to keep temporal continuity more reliable and reduce the depth propagation errors caused by occlusion. The potential key-frames would be localized in terms of clustered color variation and motion intensity. The distance of key-frame interval is also taken into account to keep the accumulated propagation errors under control and guarantee minimal user interaction. Once their depth maps are aligned with user interaction, the non-key-frames depth maps would be automatically propagated by shifted bilateral filtering. Considering that depth of objects may change due to the objects motion or camera zoom in/out effect, a bi-directional depth propagation scheme is adopted where a non-key frame is interpolated from two adjacent key frames. The experimental results show that the proposed scheme has better performance than existing 2D-to-3D scheme with fixed key-frame interval.

  13. In Situ Grown Fe2O3 Single Crystallites on Reduced Graphene Oxide Nanosheets as High Performance Conversion Anode for Sodium-Ion Batteries.

    PubMed

    Li, Ting; Qin, Aiqiong; Yang, Lanlan; Chen, Jie; Wang, Qiufan; Zhang, Daohong; Yang, Hanxi

    2017-06-14

    Electrochemical conversion reactions of metal oxides provide a new avenue to build high capacity anodes for sodium-ion batteries. However, the poor rate performance and cyclability of these conversion anodes remain a significant challenge for Na-ion battery applications because most of the conversion anodes suffer from sluggish kinetics and irreversible structural change during cycles. In this paper, we report an Fe2O3 single crystallites/reduced graphene oxide composite (Fe2O3/rGO), where the Fe2O3 single crystallites with a particle size of ∼300 nm were uniformly anchored on the rGO nanosheets, which provide a highly conductive framework to facilitate electron transport and a flexible matrix to buffer the volume change of the material during cycling. This Fe2O3/rGO composite anode shows a very high reversible capacity of 610 mAh g(-1) at 50 mA g(-1), a high Coulombic efficiency of 71% at the first cycle, and a strong cyclability with 82% capacity retention after 100 cycles, suggesting a potential feasibility for sodium-ion batteries. More significantly, the present work clearly illustrates that an electrochemical conversion anode can be made with high capacity utilization, strong rate capability, and stable cyclability through appropriately tailoring the lattice structure, particle size, and electronic conduction channels for a simple transition-metal oxide, thus offering abundant selections for development of low-cost and high-performance Na-storage electrodes.

  14. Triboelectric Nanogenerator Accelerates Highly Efficient Nonviral Direct Conversion and In Vivo Reprogramming of Fibroblasts to Functional Neuronal Cells.

    PubMed

    Jin, Yoonhee; Seo, Jungmok; Lee, Jung Seung; Shin, Sera; Park, Hyun-Ji; Min, Sungjin; Cheong, Eunji; Lee, Taeyoon; Cho, Seung-Woo

    2016-09-01

    Triboelectric nanogenerators (TENGs) can be an effective cell reprogramming platform for producing functional neuronal cells for therapeutic applications. Triboelectric stimulation accelerates nonviral direct conversion of functional induced neuronal cells from fibroblasts, increases the conversion efficiency, and induces highly matured neuronal phenotypes with improved electrophysiological functionalities. TENG devices may also be used for biomedical in vivo reprogramming.

  15. Photocatalytic Formic Acid Conversion on CdS Nanocrystals with Controllable Selectivity for H2 or CO**

    PubMed Central

    Kuehnel, Moritz F; Wakerley, David W; Orchard, Katherine L; Reisner, Erwin

    2015-01-01

    Formic acid is considered a promising energy carrier and hydrogen storage material for a carbon-neutral economy. We present an inexpensive system for the selective room-temperature photocatalytic conversion of formic acid into either hydrogen or carbon monoxide. Under visible-light irradiation (λ>420 nm, 1 sun), suspensions of ligand-capped cadmium sulfide nanocrystals in formic acid/sodium formate release up to 116±14 mmol H2 gcat−1 h−1 with >99 % selectivity when combined with a cobalt co-catalyst; the quantum yield at λ=460 nm was 21.2±2.7 %. In the absence of capping ligands, suspensions of the same photocatalyst in aqueous sodium formate generate up to 102±13 mmol CO gcat−1 h−1 with >95 % selectivity and 19.7±2.7 % quantum yield. H2 and CO production was sustained for more than one week with turnover numbers greater than 6×105 and 3×106, respectively. PMID:26201752

  16. Anatase TiO2 nanorod-decoration for highly efficient photoenergy conversion.

    PubMed

    Kim, Dong Hoe; Seong, Won Mo; Park, Ik Jae; Yoo, Eun-Sang; Shin, Seong Sik; Kim, Ju Seong; Jung, Hyun Suk; Lee, Sangwook; Hong, Kug Sun

    2013-12-07

    In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries.

  17. Magnetic flux conversion in the DIII-D high-beta hybrid scenario

    NASA Astrophysics Data System (ADS)

    Taylor, N. Z.; Luce, T. C.; La Haye, R. J.; Petty, C. C.; Piovesan, P.

    2016-10-01

    In DIII-D hybrid scenario discharges, the rate of poloidal magnetic energy consumption is more than the rate of energy flow from the poloidal field coils. This is evidence that there is a conversion of toroidal flux to poloidal flux, which may account for a process known as flux pumping that leads to anomalous broadening of the current profile. The hybrid is a promising high confinement scenario for ITER. The broader current profile aids discharge sustainment by raising the minimum safety factor above unity thereby avoiding sawtooth-triggered 2/1 tearing modes that spoil energy confinement. During long ( 1.5s) stationary intervals with constant stored magnetic energy, a significant flux state deficit rate >10 mV was observed. This anomalous consumption of poloidal flux only occurred in discharges with βN > 2.5 and when a relatively benign 3/2 tearing mode was present. This suggests the tearing mode plays a critical role in flux conversion. Studies have shown that 3D core displacements can lead to flux conversion, suggesting that the 3/2 tearing mode and its 2/2 side band produce helical perturbations in the core velocity and magnetic field capable of producing a dynamo EMF that drives the observed current redistribution. Supported by the US DOE under DE-AC05-06OR23100 and DE-FC02-04ER54698.

  18. Thick sputtered tantalum coatings for high-temperature energy conversion applications

    SciTech Connect

    Stelmakh, Veronika Peykov, Daniel; Chan, Walker R.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan; Castillo, Robert; Coulter, Kent; Wei, Ronghua

    2015-11-15

    Thick sputtered tantalum (Ta) coatings on polished Inconel were investigated as a potential replacement for bulk refractory metal substrates used for high-temperature emitters and absorbers in thermophotovoltaic energy conversion applications. In these applications, high-temperature stability and high reflectance of the surface in the infrared wavelength range are critical in order to sustain operational temperatures and reduce losses due to waste heat. The reflectance of the coatings (8 and 30 μm) was characterized with a conformal protective hafnia layer as-deposited and after one hour anneals at 700, 900, and 1100 °C. To further understand the high-temperature performance of the coatings, the microstructural evolution was investigated as a function of annealing temperature. X-ray diffraction was used to analyze the texture and residual stress in the coatings at four reflections (220, 310, 222, and 321), as-deposited and after anneal. No significant changes in roughness, reflectance, or stress were observed. No delamination or cracking occurred, even after annealing the coatings at 1100 °C. Overall, the results of this study suggest that the thick Ta coatings are a promising alternative to bulk substrates and pave the way for a relatively low-cost and easily integrated platform for nanostructured devices in high-temperature energy conversion applications.

  19. X-ray Conversion Efficiency of high-Z hohlraum wall materials for indirect drive ignition

    SciTech Connect

    Dewald, E; Rosen, M; Glenzer, S H; Suter, L J; Girard, F; Jadaud, J P; Schein, J; Constantin, C G; Neumayer, P; Landen, O

    2008-02-22

    We measure the conversion efficiency of 351 nm laser light to soft x-rays (0.1-5 keV) for Au, U and high Z mixtures 'cocktails' used for hohlraum wall materials in indirect drive ICF. We use spherical targets in a direct drive geometry, flattop laser pulses and laser smoothing with phase plates to achieve constant and uniform laser intensities of 10{sup 14} and 10{sup 15} W/cm{sup 2} over the target surface that are relevant for the future ignition experiments on NIF. The absolute time and spectrally-resolved radiation flux is measured with a multichannel soft x-ray power diagnostic. The conversion efficiency is then calculated by dividing the measured x-ray power by the incident laser power from which the measured laser backscattering losses is subtracted. After {approx}0.5 ns, the time resolved x-ray conversion efficiency reaches a slowly increasing plateau of 95% at 10{sup 14} W/cm{sup 2} laser intensity and of 80% at 10{sup 15} W/cm{sup 2}. The M-band flux (2-5 keV) is negligible at 10{sup 14} W/cm{sup 2} reaching {approx}1% of the total x-ray flux for all target materials. In contrast, the M-band flux is significant and depends on the target material at 10{sup 15} W/cm{sup 2} laser intensity, reaching values between 10% of the total flux for U and 27% for Au. Our LASNEX simulations show good agreement in conversion efficiency and radiated spectra with data when using XSN atomic physics model and a flux limiter of 0.15, but they underestimate the generated M-band flux.

  20. X-ray conversion efficiency of high-Z hohlraum wall materials for indirect drive ignition

    NASA Astrophysics Data System (ADS)

    Dewald, E. L.; Rosen, M.; Glenzer, S. H.; Suter, L. J.; Girard, F.; Jadaud, J. P.; Schein, J.; Constantin, C.; Wagon, F.; Huser, G.; Neumayer, P.; Landen, O. L.

    2008-07-01

    The conversion efficiency of 351nm laser light to soft x rays (0.1-5keV) was measured for Au, U, and high Z mixture "cocktails" used as hohlraum wall materials in indirect drive fusion experiments. For the spherical targets in a direct drive geometry, flattop laser pulses and laser smoothing with phase plates are employed to achieve constant and uniform laser intensities of 1014 and 1015W/cm2 over the target surface that are relevant for the future ignition experiments at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, 228 (2004)]. The absolute time and spectrally resolved radiation flux is measured with a multichannel soft x-ray power diagnostic. The conversion efficiency is then calculated by dividing the measured x-ray power by the incident laser power from which the measured laser backscattering losses are subtracted. After ˜0.5ns, the time resolved x-ray conversion efficiency reaches a slowly increasing plateau of 95% at 1014W/cm2 laser intensity and of 80% at 1015W/cm2. The M-band flux (2-5keV) is negligible at 1014W/cm2 reaching ˜1% of the total x-ray flux for all target materials. In contrast, the M-band flux is significant and depends on the target material at 1015W/cm2 laser intensity, reaching values between 10% of the total flux for U and 27% for Au. LASNEX simulations [G. B. Zimmerman and W. L. Kruer, Comm. Plasma Phys. Contr. Fusion 2, 51 (1975)] show good agreement in conversion efficiency and radiated spectra with data when using XSN atomic physics model and a flux limiter of 0.15, but they underestimate the generated M-band flux.

  1. Near-infrared light controlled photocatalytic activity of carbon quantum dots for highly selective oxidation reaction

    NASA Astrophysics Data System (ADS)

    Li, Haitao; Liu, Ruihua; Lian, Suoyuan; Liu, Yang; Huang, Hui; Kang, Zhenhui

    2013-03-01

    Selective oxidation of alcohols is a fundamental and significant transformation for the large-scale production of fine chemicals, UV and visible light driven photocatalytic systems for alcohol oxidation have been developed, however, the long wavelength near infrared (NIR) and infrared (IR) light have not yet fully utilized by the present photocatalytic systems. Herein, we reported carbon quantum dots (CQDs) can function as an effective near infrared (NIR) light driven photocatalyst for the selective oxidation of benzyl alcohol to benzaldehyde. Based on the NIR light driven photo-induced electron transfer property and its photocatalytic activity for H2O2 decomposition, this metal-free catalyst could realize the transformation from benzyl alcohol to benzaldehyde with high selectivity (100%) and conversion (92%) under NIR light irradiation. HO&z.rad; is the main active oxygen specie in benzyl alcohol selective oxidative reaction confirmed by terephthalic acid photoluminescence probing assay (TA-PL), selecting toluene as the substrate. Such metal-free photocatalytic system also selectively converts other alcohol substrates to their corresponding aldehydes with high conversion, demonstrating a potential application of accessing traditional alcohol oxidation chemistry.Selective oxidation of alcohols is a fundamental and significant transformation for the large-scale production of fine chemicals, UV and visible light driven photocatalytic systems for alcohol oxidation have been developed, however, the long wavelength near infrared (NIR) and infrared (IR) light have not yet fully utilized by the present photocatalytic systems. Herein, we reported carbon quantum dots (CQDs) can function as an effective near infrared (NIR) light driven photocatalyst for the selective oxidation of benzyl alcohol to benzaldehyde. Based on the NIR light driven photo-induced electron transfer property and its photocatalytic activity for H2O2 decomposition, this metal-free catalyst could realize

  2. Selective Conversion of Lignin-Derivable 4-Alkylguaiacols to 4-Alkylcyclohexanols over Noble and Non-Noble-Metal Catalysts

    SciTech Connect

    Schutyser, Wouter; Van den Bossche, Gil; Raaffels, Anton; Van den Bosch, Sander; Koelewijn, Steven-Friso; Renders, Tom; Sels, Bert F.

    2016-10-03

    Recent lignin-first catalytic lignocellulosic biorefineries produce large quantities of two potential platform chemicals, 4-n-propylguaiacol (PG) and 4-n-propylsyringol. Because conversion into 4-n-propylcyclohexanol (PCol), a precursor for novel polymer building blocks, presents a promising valorization route, reductive demethoxylation of PG was examined here in the liquid-phase over three commercial hydrogenation catalysts, viz. 5 wt % Ru/C, 5 wt % Pd/C and 65 wt % Ni/SiO2-Al2O3, at elevated temperatures ranging from 200 to 300 degrees C under hydrogen atmosphere. Kinetic profiles suggest two parallel conversion pathways: Pathway I involves PG hydrogenation to 4-n-propyl-2-methoxycyclohexanol (PMCol), followed by its demethoxylation to PCol, whereas Pathway II constitutes PG hydrodemethoxylation to 4-n-propylphenol (PPh), followed by its hydrogenation into PCol. The slowest step in the catalytic formation of PCol is the reductive methoxy removal from PMCol. Moreover, under the applied reaction conditions, PCol may react further into hydrocarbons. The following criteria are therefore essential to reach a high PCol yield: (i) catalytic pathway II is preferred as this route does not involve stable intermediates; (ii) reactivity of PMCol should be higher than that of PCol, and (iii) the overall carbon balance should be high. Both the catalyst type and the reaction conditions have a substantial impact on the PCol yield. Only the commercial Ni catalyst meets the three criteria, provided the reaction is performed at 250 degrees C in hexadecane. Additional advantages of this solvent choice are a high boiling point (low operational pressure in closed reactor systems), high solubility of PG and derived products, high thermal, reductive stability, and easy derivability from fatty biomass feedstock. This Ni catalyst also showed an excellent stability in recycling runs and is capable of converting highly concentrated (up to 20 wt %) PG in hexadecane. Ru and Pd on carbon

  3. Probabilistic selection of high-redshift quasars

    NASA Astrophysics Data System (ADS)

    Mortlock, Daniel J.; Patel, Mitesh; Warren, Stephen J.; Hewett, Paul C.; Venemans, Bram P.; McMahon, Richard G.; Simpson, Chris

    2012-01-01

    High-redshift quasars (HZQs) with redshifts of z ≳ 6 are so rare that any photometrically selected sample of sources with HZQ-like colours is likely to be dominated by Galactic stars and brown dwarfs scattered from the stellar locus. It is impractical to re-observe all such candidates, so an alternative approach was developed in which Bayesian model comparison techniques are used to calculate the probability that a candidate is a HZQ, Pq, by combining models of the quasar and star populations with the photometric measurements of the object. This method was motivated specifically by the large number of HZQ candidates identified by cross-matching the UKIRT (United Kingdom Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) to the Sloan Digital Sky Survey (SDSS): in the ? covered by the LAS in the UKIDSS Eighth Data Release (DR8) there are ˜9 × 103 real astronomical point sources with the measured colours of the target quasars, of which only ˜10 are expected to be HZQs. Applying Bayesian model comparison to the sample reveals that most sources with HZQ-like colours have Pq≲ 0.1 and can be confidently rejected without the need for any further observations. In the case of the UKIDSS DR8 LAS, there were just 107 candidates with Pq≥ 0.1; these objects were prioritized for re-observation by ranking according to Pq (and their likely redshift, which was also inferred from the photometric data). Most candidates were rejected after one or two (moderate-depth) photometric measurements by recalculating Pq using the new data. That left 12 confirmed HZQs, six of which were previously identified in the SDSS and six of which were new UKIDSS discoveries. The high efficiency of this Bayesian selection method suggests that it could usefully be extended to other HZQ surveys (e.g. searches by the Panoramic Survey Telescope And Rapid Response System, Pan-STARRS, or the Visible and Infrared Survey Telescope for Astronomy, VISTA) as well as to other

  4. High Temperature Fusion Reactor Cooling Using Brayton Cycle Based Partial Energy Conversion

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.; Sawicki, Jerzy T.

    2003-01-01

    For some future space power systems using high temperature nuclear heat sources most of the output energy will be used in other than electrical form, and only a fraction of the total thermal energy generated will need to be converted to electrical work. The paper describes the conceptual design of such a partial energy conversion system, consisting of a high temperature fusion reactor operating in series with a high temperature radiator and in parallel with dual closed cycle gas turbine (CCGT) power systems, also referred to as closed Brayton cycle (CBC) systems, which are supplied with a fraction of the reactor thermal energy for conversion to electric power. Most of the fusion reactor's output is in the form of charged plasma which is expanded through a magnetic nozzle of the interplanetary propulsion system. Reactor heat energy is ducted to the high temperature series radiator utilizing the electric power generated to drive a helium gas circulation fan. In addition to discussing the thermodynamic aspects of the system design the authors include a brief overview of the gas turbine and fan rotor-dynamics and proposed bearing support technology along with performance characteristics of the three phase AC electric power generator and fan drive motor.

  5. Prion strain interactions are highly selective

    PubMed Central

    Nilsson, K. Peter R.; Joshi-Barr, Shivanjali; Winson, Olivia; Sigurdson, Christina J.

    2010-01-01

    Various misfolded and aggregated neuronal proteins commonly co-exist in neurodegenerative disease, but whether the proteins co-aggregate and alter the disease pathogenesis is unclear. Here we used mixtures of distinct prion strains, which are believed to differ in conformation, to test the hypothesis that two different aggregates interact and change the disease in vivo. We tracked two prion strains in mice histopathologically and biochemically, as well as by spectral analysis of plaque-bound polythiophene acetic acid (PTAA), a conformation-sensitive fluorescent amyloid ligand. We found that prion strains interacted in a highly selective and strain-specific manner, with either (i) no interaction, (ii) hybrid plaque formation, or (iii) blockage of one strain by a second (interference). The hybrid plaques were maintained upon further passage in vivo and each strain seemed to maintain its original conformational properties, suggesting that one strain served only as a scaffold for aggregation of the second strain. These findings not only further our understanding of prion strain interactions, but also directly demonstrate interactions that may occur in other protein aggregate mixtures. PMID:20826672

  6. High photocurrent conversion efficiency in self-organized porous WO{sub 3}

    SciTech Connect

    Berger, S.; Tsuchiya, H.; Ghicov, A.; Schmuki, P.

    2006-05-15

    Self-organized porous structures of WO{sub 3} were grown on tungsten by an anodic oxidation, and their photoelectrochemical properties were characterized. The porous WO{sub 3} layers show a regular morphology with average pore sizes of approximately 70 nm and a pore wall thickness of approximately 10 nm. As formed layers show an amorphous structure but the layers can be altered to a crystalline monoclinic structure by thermal annealing. The annealed porous WO{sub 3} layers show a very high specific photocurrent conversion efficiency.

  7. High performance materials in coal conversion utilization. Technical progress report, October 1, 1994--December 31, 1994

    SciTech Connect

    1995-01-01

    This is the fifth quarterly report on a three year grant regarding {open_quotes}High Performance Materials in Coal Conversion Utilization.{close_quotes} The grant is for a joint university/industry effort under the US Department of Energy (DOE) University Coal Research Program. The University of Tennessee Space Institute (UTSI) is the prime contractor and The University of Pennsylvania and Lanxide Corporation are subcontractors. UTSI has completed the planned laboratory exposure tests involving pulverized coal slag on the production Lanxide DIMOX{trademark} ceramic composite material. In addition, the strength testing (at temperature) of C-ring sections of the production composite is complete.

  8. INDEPENDENT STRATUM FORMATION ON THE AVIAN SEX CHROMOSOMES REVEALS INTER-CHROMOSOMAL GENE CONVERSION AND PREDOMINANCE OF PURIFYING SELECTION ON THE W CHROMOSOME

    PubMed Central

    Wright, Alison E; Harrison, Peter W; Montgomery, Stephen H; Pointer, Marie A; Mank, Judith E

    2014-01-01

    We used a comparative approach spanning three species and 90 million years to study the evolutionary history of the avian sex chromosomes. Using whole transcriptomes, we assembled the largest cross-species dataset of W-linked coding content to date. Our results show that recombination suppression in large portions of the avian sex chromosomes has evolved independently, and that long-term sex chromosome divergence is consistent with repeated and independent inversions spreading progressively to restrict recombination. In contrast, over short-term periods we observe heterogeneous and locus-specific divergence. We also uncover four instances of gene conversion between both highly diverged and recently evolved gametologs, suggesting a complex mosaic of recombination suppression across the sex chromosomes. Lastly, evidence from 16 gametologs reveal that the W chromosome is evolving with a significant contribution of purifying selection, consistent with previous findings that W-linked genes play an important role in encoding sex-specific fitness. PMID:25066800

  9. Suppression of sludge formation by two-stage hydrocracking of vacuum residue at high conversion

    SciTech Connect

    Mochida, I.; Zhao, X.; Sakanishi, K. )

    1990-12-01

    This paper reports on hydrocracked products from Arabian light vacuum residue at high conversion into distillate ({gt}50%) that were analyzed in order to reveal how sludge formation was suppressed in the two-stage reaction. Although the asphaltene in the starting residue was highly soluble in the starting maltene in spite of is largest molecular weight, single-stage hydrocracking at a higher temperature of 420{degrees}C increased the aromaticity of the asphaltene through extensive deaklylation and dehydrogenation, leading to sludge formation. In contrast, two-stage hydrocracking at 390{degrees}C--3 h/420{degrees}C--1/h accomplished effective depolymerization of the asphaltene, high conversion being achieved without sludge. The carbon aromaticity (f{sub a}) of the produced asphaltene was maintained rather low, although its amount in the product was much the same regardless of the reaction conditions. The heptane-soluble maltenes in the hydrocracked oils exhibited variable dissolving abilities against the asphaltene according to the content and aromaticity of its aromatic fraction, also influencing sludge formation. Hydrocracking produced paraffins through the hydrogenative deaklylation of long-chain alkylbenzenes, decreasing f{sub a} and the dissolving ability of the hydrocracked maltene.

  10. Pump-linewidth-tolerant optical wavelength conversion for high-order QAM signals using coherent pumps.

    PubMed

    Lu, Guo-Wei; Albuquerque, André; Puttnam, Benjamin J; Sakamoto, Takahide; Drummond, Miguel; Nogueira, Rogério; Kanno, Atsushi; Shinada, Satoshi; Wada, Naoya; Kawanishi, Tetsuya

    2014-03-10

    Optical wavelength conversion (OWC) is expected to be a desirable function in future optical transparent networks. Since high-order quadrature amplitude modulation (QAM) is more sensitive to the phase noise, in the OWC of high-order QAM signals, it is crucial to suppress the extra noise introduced in the OWC subsystem, especially for the scenario with multiple cascaded OWCs. Here, we propose and experimentally demonstrate a pump-linewidth-tolerant OWC scheme suitable for high-order QAM signals using coherent two-tone pumps. Using 3.5-MHz-linewidth distributed feedback (DFB) lasers as pump sources, our scheme enables wavelength conversion of both 16QAM and 64QAM signals with negligible power penalty, in a periodically-poled Lithium Niobate (PPLN) waveguide based OWC. We also demonstrate the performance of pump phase noise cancellation, showing that such coherent two-tone pump schemes can eliminate the need for ultra-narrow linewidth pump lasers and enable practical implementation of low-cost OWC in future dynamic optical networks.

  11. High-efficiency polarization conversion based on spatial dispersion modulation of spoof surface plasmon polaritons.

    PubMed

    Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Ma, Hua; Wang, Jiafu; Wang, Jun; Xu, Zhuo

    2016-10-31

    In this paper, we propose to achieve high-efficiency polarization conversion based on spatial dispersion modulation of spoof surface plasmon polaritons (SSPP). Different k is firstly designed in the two transverse directions by aligning an SSPP-supporting fishbone structure in y direction while maintaining free space in x direction. The orthogonal phase difference is introduced by larger k of SSPP waves for y-polarized component of incident waves. Meanwhile, to achieve high efficiency, gradient k in z-direction is designed so that the y-polarized component of incident waves can be coupled perfectly as SSPP waves. By rotating the fishbone structure with respect to the polarization direction of incident waves, different polarization states for transmitted waves can be realized. As an example, a polarization converter prototype with the central working frequency f = 8GHz was designed, fabricated, and measured. Both the simulation and experiment demonstrate the high-efficiency linear-to-circular (LTC) polarization conversion in 6.9-9.6GHz.

  12. Selective nickel-catalyzed conversion of model and lignin-derived phenolic compounds to cyclohexanone-based polymer building blocks.

    PubMed

    Schutyser, Wouter; Van den Bosch, Sander; Dijkmans, Jan; Turner, Stuart; Meledina, Maria; Van Tendeloo, Gustaaf; Debecker, Damien P; Sels, Bert F

    2015-05-22

    Valorization of lignin is essential for the economics of future lignocellulosic biorefineries. Lignin is converted into novel polymer building blocks through four steps: catalytic hydroprocessing of softwood to form 4-alkylguaiacols, their conversion into 4-alkylcyclohexanols, followed by dehydrogenation to form cyclohexanones, and Baeyer-Villiger oxidation to give caprolactones. The formation of alkylated cyclohexanols is one of the most difficult steps in the series. A liquid-phase process in the presence of nickel on CeO2 or ZrO2 catalysts is demonstrated herein to give the highest cyclohexanol yields. The catalytic reaction with 4-alkylguaiacols follows two parallel pathways with comparable rates: 1) ring hydrogenation with the formation of the corresponding alkylated 2-methoxycyclohexanol, and 2) demethoxylation to form 4-alkylphenol. Although subsequent phenol to cyclohexanol conversion is fast, the rate is limited for the removal of the methoxy group from 2-methoxycyclohexanol. Overall, this last reaction is the rate-limiting step and requires a sufficient temperature (>250 °C) to overcome the energy barrier. Substrate reactivity (with respect to the type of alkyl chain) and details of the catalyst properties (nickel loading and nickel particle size) on the reaction rates are reported in detail for the Ni/CeO2 catalyst. The best Ni/CeO2 catalyst reaches 4-alkylcyclohexanol yields over 80 %, is even able to convert real softwood-derived guaiacol mixtures and can be reused in subsequent experiments. A proof of principle of the projected cascade conversion of lignocellulose feedstock entirely into caprolactone is demonstrated by using Cu/ZrO2 for the dehydrogenation step to produce the resultant cyclohexanones (≈80 %) and tin-containing beta zeolite to form 4-alkyl-ε-caprolactones in high yields, according to a Baeyer-Villiger-type oxidation with H2 O2 .

  13. Complex signatures of locus-specific selective pressures and gene conversion on Human Growth Hormone/Chorionic Somatomammotropin genes.

    PubMed

    Sedman, Laura; Padhukasahasram, Badri; Kelgo, Piret; Laan, Maris

    2008-10-01

    Reduced birth weight and slow neonatal growth are risks correlated with the development of common diseases in adulthood. The Human Growth Hormone/Chorionic Somatomammotropin (hGH/CSH) gene cluster (48 kb) at 17q22-24, consisting of one pituitary-expressed postnatal (GH1) and four placental genes (GH2, CSH1, CSH2, and CSHL1) may contribute to common variation in intrauterine and infant growth, and also to the regulation of feto-maternal and adult glucose metabolism. In contrast to GH1, there are limited genetic data on the hGH/CSH genes expressed in utero. We report the first survey of sequence variation encompassing all five hGH/CSH genes. Resequencing identified 113 SNPs/indels (ss86217675-ss86217787 in dbSNP) including 66 novel variants, and revealed remarkable differences in diversity patterns among the homologous duplicated genes as well as between the study populations of European (Estonians), Asian (Han Chinese), and African (Mandenkalu) ancestries. A dominant feature of the hGH/CSH region is hyperactive gene conversion, with the rate exceeding tens to hundreds of times the rate of reciprocal crossing-over and resulting in near absence of linkage disequilibrium. The initiation of gene conversion seems to be uniformly distributed because the data do not predict any recombination hotspots. Signatures of different selective constraints acting on each gene indicate functional specification of the hGH/CSH genes. Most strikingly, the GH2 coding for placental growth hormone shows strong intercontinental diversification (F(ST)=0.41-0.91; p<10(-6)) indicative of balancing selection, whereas the flanking CSH1 exhibits low population differentiation (F(ST)=0.03-0.09), low diversity (non-Africans, pi=8-9 x 10(-5); Africans, pi=8.2 x 10(-4)), and one dominant haplotype worldwide, consistent with purifying selection. The results imply that the success of an association study targeted to duplicated genes may be enhanced by prior resequencing of the study population in order

  14. A Hierarchical Bipyridine-Constructed Framework for Highly Efficient Carbon Dioxide Capture and Catalytic Conversion.

    PubMed

    Dai, Zhifeng; Sun, Qi; Liu, Xiaolong; Guo, Liping; Li, Jixue; Pan, Shuxiang; Bian, Chaoqun; Wang, Liang; Hu, Xin; Meng, Xiangju; Zhao, Leihong; Deng, Feng; Xiao, Feng-Shou

    2017-03-22

    As a C1 feedstock, CO2 has the potential to be uniquely highly economical in both a chemical and a financial sense. Porous materials bearing particular binding and active sites that can capture and convert CO2 simultaneously are promising candidates for CO2 utilization. In this work, a bipyridine-constructed polymer featuring a high surface area, a hierarchical porous structure, and excellent stability was synthesized through free-radical polymerization. After metalation, the resultant catalysts exhibited superior activities in comparison with those of their homogeneous counterparts in the cycloaddition of CO2 to epoxides. The high performance of the heterogeneous catalysts originates from cooperative effects between the CO2 -philic polymer and the embedded metal species. In addition, the catalysts showed excellent stabilities and are readily recyclable; thus, they are promising for practical utilization for the conversion of CO2 into value-added chemicals.

  15. Orbital angular momentum modes of high-gain parametric down-conversion

    NASA Astrophysics Data System (ADS)

    Beltran, Lina; Frascella, Gaetano; Perez, Angela M.; Fickler, Robert; Sharapova, Polina R.; Manceau, Mathieu; Tikhonova, Olga V.; Boyd, Robert W.; Leuchs, Gerd; Chekhova, Maria V.

    2017-04-01

    Light beams with orbital angular momentum (OAM) are convenient carriers of quantum information. They can also be used for imparting rotational motion to particles and providing high resolution in imaging. Due to the conservation of OAM in parametric down-conversion (PDC), signal and idler photons generated at low gain have perfectly anti-correlated OAM values. It is interesting to study the OAM properties of high-gain PDC, where the same OAM modes can be populated with large, but correlated, numbers of photons. Here we investigate the OAM spectrum of high-gain PDC and show that the OAM mode content can be controlled by varying the pump power and the configuration of the source. In our experiment, we use a source consisting of two nonlinear crystals separated by an air gap. We discuss the OAM properties of PDC radiation emitted by this source and suggest possible modifications.

  16. High-temperature, high-power-density thermionic energy conversion for space

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1977-01-01

    Theoretic converter outputs and efficiencies indicate the need to consider thermionic energy conversion (TEC) with greater power densities and higher temperatures within reasonable limits for space missions. Converter-output power density, voltage, and efficiency as functions of current density were determined for 1400-to-2000 K emitters with 725-to-1000 K collectors. The results encourage utilization of TEC with hotter-than-1650 K emitters and greater-than-6W sq cm outputs to attain better efficiencies, greater voltages, and higher waste-heat-rejection temperatures for multihundred-kilowatt space-power applications. For example, 1800 K, 30 A sq cm TEC operation for NEP compared with the 1650 K, 5 A/sq cm case should allow much lower radiation weights, substantially fewer and/or smaller emitter heat pipes, significantly reduced reactor and shield-related weights, many fewer converters and associated current-collecting bus bars, less power conditioning, and lower transmission losses. Integration of these effects should yield considerably reduced NEP specific weights.

  17. Design of selective emitting media within a cylindrical tube for conversion of wasted heat energy to electrical energy

    NASA Astrophysics Data System (ADS)

    Starvaggi, P.; Hoffman, M.; Clemons, C. B.; Young, G. W.

    2011-01-01

    Thermophotovoltaic (TPV) energy conversion is the conversion of heat energy to electrical energy via light. This manuscript focuses on the geometric design of emitting material within an exhaust tube to convert wasted heat energy to light, and achieve an optimal amount of irradiance at the PV diode cells. Due to the large value of the absorption coefficient for the selectively emitting erbia-doped nanofibers under discussion, the diffusion approximation to the equation of radiation transfer is used. This approximate equation is solved for emission from hot-spot sources within the emitting material. Several geometric distributions of the emitting material are considered. Within an axisymmetric geometry all erbia-doped nanofibers, all quartz wool, and mixtures of disk-shaped or cylindrical shell shaped distributions of nanofibers and wool are investigated. Within a polar geometry all erbia-doped nanofibers, all quartz wool, and mixtures of spoke-shaped or cylindrical shell shaped distributions are investigated. In both geometries the mixture distributions consist of alternating thin layers of emitting and non-emitting material. Homogenization techniques are applied to these distributions to define expressions for the effective absorption and scattering coefficients for these spatially distributed emitting structures. The effective expressions are input into the diffusion approximation that is solved for the spectral irradiance. The net radiation obtained from these emitting structures is examined to optimize the geometry of the TPV material to maximize emission with use of minimal TPV material. Results show that disk-shaped bands or spokes allow for maximum irradiation in the radial direction toward the diode collectors. A large volume fraction of erbia-doped nanofibers is optimal when hot spots are close to the diodes. Smaller volume fractions work better when hot spots are away from the diodes due to reabsorption of emitted light by the emitting material.

  18. Porous Pd nanoparticles with high photothermal conversion efficiency for efficient ablation of cancer cells.

    PubMed

    Xiao, Jia-Wen; Fan, Shi-Xuan; Wang, Feng; Sun, Ling-Dong; Zheng, Xiao-Yu; Yan, Chun-Hua

    2014-04-21

    Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 10(7) M(-1) cm(-1)), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water and illuminated with an 808 nm laser, the porous Pd NPs give a photothermal conversion efficiency as high as 93.4%, which is comparable to the efficiency of Au nanorods we synthesized (98.6%). As the porous Pd NPs show broadband NIR absorption (650-1200 nm), this allows us to choose multiple laser wavelengths for photothermal therapy. In vitro photothermal heating of HeLa cells in the presence of porous Pd NPs leads to 100% cell death under 808 nm laser irradiation (8 W cm(-2), 4 min). For photothermal heating using 730 nm laser, 70% of HeLa cells were killed after 4 min irradiation at a relative low power density of 6 W cm(-2). These results demonstrated that the porous Pd nanostructure is an attractive photothermal agent for cancer therapy.

  19. Doubly resonant metallic nanostructure for high conversion efficiency of second harmonic generation.

    PubMed

    Park, Sinjeung; Hahn, Jae W; Lee, Jae Yong

    2012-02-27

    The recent discovery of strong nonlinear emission in metallic nanostructures has offered possibilities for realization of functional nano photonic devices. Here, we demonstrate a novel design of a plasmonic nano device for high conversion efficiency of second harmonic generation. A 4 × 4 bowtie aperture array is fabricated to have both plasmonic resonance for local field enhancement of the fundamental wave and Fabry-Pérot resonance for high transmission of second harmonic wave. Combining nano structures for exciting surface plasmon polariton and suppressing higher order diffraction and anti-reflection layer, we achieve a second harmonic conversion efficiency of 1.4 × 10(-8) that is nearly an order of magnitude larger than the results published in recent literatures. We also theoretically analyze evidences of the role of double resonances tuned to the fundamental wave and the second harmonic wave, resulting in the augmentation of second harmonic response approximately an order of magnitude greater than that without the help of the resonance.

  20. Simulation and demonstration of magnetohydrodynamic energy conversion in a high-temperature inert gas

    SciTech Connect

    Murakami, Tomoyuki; Okuno, Yoshihiro

    2009-03-15

    The present paper describes high-density magnetohydrodynamic (MHD) energy conversion in a high-temperature seed-free argon plasma, for which a quasi-three-dimensional numerical simulation and a single-pulse shock-tunnel-based demonstration are conducted. The numerical model simulates the two-dimensional profiles of both the electron and the heavy-particle system of the supersonic argon plasma flow, of which the total inflow temperature is 8000 K. The MHD power-generating experiment clarifies the relationship between the plasma quality and the energy conversion efficiency as functions of the total inflow temperature (7600-9600 K) and the applied magnetic flux density (up to 4.0 T). The increase in the total inflow temperature from 7600 to 9400 K and the application of magnetic flux with density of 0.5-1.2 T change the plasma state; unstable behavior accompanied by an inhomogeneous structure is transformed to a homogeneous and stable state, which results in the significant improvement of the power generation performance. Even in low-density magnetic flux, the attained generator performance is comparable or superior to previous results obtained using a conventional low-temperature seeded gas.

  1. Elliptical selection experiment for the estimation of genetic parameters of the growth rate and feed conversion ratio in rabbits.

    PubMed

    Piles, M; Gomez, E A; Rafel, O; Ramon, J; Blasco, A

    2004-03-01

    Two elliptical selection experiments were performed in two contemporary sire lines of rabbits (C and R) in order to optimize the experimental design for estimating the genetic parameters of the growth rate (GR) and feed conversion ratio (FCR). Twelve males and 19 females from line C, and 13 males and 23 females from line R, were selected from an ellipse defined by a quadratic index based on these traits. Data from 160 rabbits of each of the parental generations of lines C and R and their offspring (275 and 266 animals, respectively) were used for the analysis. A Bayesian framework was adopted for inference. Marginal posterior distributions of the genetic parameters were obtained by Gibbs sampling. An animal model including batch, parity order, litter size, and common environmental litter effects was assumed. Posterior means (posterior standard deviations) for heritabilities of GR and FCR were estimated to be 0.31 (0.10) and 0.31 (0.10), respectively, in line C and 0.21 (0.08) and 0.25 (0.12) in line R. Posterior means of the proportion of the variance due to common litter environmental effects were 0.14 (0.06) and 0.21 (0.06) for GR and FCR, respectively, in line C and 0.17 (0.06) and 0.22 (0.06) in line R. Posterior means of genetic correlation between both traits were -0.49 (0.25) in line C and -0.47 (0.32) in line R, indicating that selection for GR was expected to result in a similar correlated response in FCR in both lines.

  2. Anatase TiO2 nanorod-decoration for highly efficient photoenergy conversion

    NASA Astrophysics Data System (ADS)

    Kim, Dong Hoe; Seong, Won Mo; Park, Ik Jae; Yoo, Eun-Sang; Shin, Seong Sik; Kim, Ju Seong; Jung, Hyun Suk; Lee, Sangwook; Hong, Kug Sun

    2013-11-01

    In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries.In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile

  3. A method for highly efficient exact gene replacement without selection

    PubMed Central

    Cross, Frederick R.; Pecani, Kresti

    2013-01-01

    We describe a highly efficient method for exact gene replacement in budding yeast. Induction of rapid and efficient recombination in an entire cell population results in at least 50% of the recombinants undergoing a specific switch of the endogenous copy to a specific mutated allele, with no remaining markers or remnant of foreign DNA, without selection. To accomplish this, a partial copy of the replacement allele, followed by an HO cut site, is installed adjacent to the wild-type locus, in a GAL-HO MATa-inc background. HO induction results in near-quantitative site cleavage and recombination/gene conversion, resulting in either regeneration of wild-type, or switch of the endogenous allele to the mutant, with accompanying deletion of intervening marker sequences, yielding an exact replacement. Eliminating the need for selection (over days) of rare recombinants removes concerns about second-site suppressor mutations, and also allows direct phenotypic analysis even of lethal gene replacements without the need of a method to make the lethality conditional, or to employ regulated promoters of unknown strength compared to the endogenous promoter. To test this method, we tried two known lethal gene replacements, substituting the non-essential CDH1 gene with a dominantly lethal version mutated for its Cdk phosphorylation sites, and substituting the essential CDC28 gene with two recessively lethal versions, one containing an early stop codon and another one inactivating Cdc28 kinase activity. We also tested a gene replacement of unknown phenotypic consequences: replacing the non-essential CLB3 B-type cyclin with a version lacking its destruction box. PMID:21246629

  4. Properties and Frequency Conversion of High-Brightness Diode-Laser Systems

    NASA Astrophysics Data System (ADS)

    Boller, Klaus-Jochen; Beier, Bernard; Wallenstein, Richard

    An overview of recent developments in the field of high-power, high-brightness diode-lasers, and the optically nonlinear conversion of their output into other wavelength ranges, is given. We describe the generation of continuous-wave (CW) laser beams at power levels of several hundreds of milliwatts to several watts with near-perfect spatial and spectral properties using Master-Oscillator Power-Amplifier (MOPA) systems. With single- or double-stage systems, using amplifiers of tapered or rectangular geometry, up to 2.85 W high-brightness radiation is generated at wavelengths around 810nm with AlGaAs diodes. Even higher powers, up to 5.2W of single-frequency and high spatial quality beams at 925nm, are obtained with InGaAs diodes. We describe the basic properties of the oscillators and amplifiers used. A strict proof-of-quality for the diode radiation is provided by direct and efficient nonlinear optical conversion of the diode MOPA output into other wavelength ranges. We review recent experiments with the highest power levels obtained so far by direct frequency doubling of diode radiation. In these experiments, 100mW single-frequency ultraviolet light at 403nm was generated, as well as 1W of single-frequency blue radiation at 465nm. Nonlinear conversion of diode radiation into widely tunable infrared radiation has recently yielded record values. We review the efficient generation of widely tunable single-frequency radiation in the infrared with diode-pumped Optical Parametric Oscillators (OPOs). With this system, single-frequency output radiation with powers of more than 0.5W was generated, widely tunable around wavelengths of 2.1,m and 1.65,m and with excellent spectral and spatial quality. These developments are clear indicators of recent advances in the field of high-brightness diode-MOPA systems, and may emphasize their future central importance for applications within a vast range of optical

  5. Porous Pd nanoparticles with high photothermal conversion efficiency for efficient ablation of cancer cells

    NASA Astrophysics Data System (ADS)

    Xiao, Jia-Wen; Fan, Shi-Xuan; Wang, Feng; Sun, Ling-Dong; Zheng, Xiao-Yu; Yan, Chun-Hua

    2014-03-01

    Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 107 M-1 cm-1), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water and illuminated with an 808 nm laser, the porous Pd NPs give a photothermal conversion efficiency as high as 93.4%, which is comparable to the efficiency of Au nanorods we synthesized (98.6%). As the porous Pd NPs show broadband NIR absorption (650-1200 nm), this allows us to choose multiple laser wavelengths for photothermal therapy. In vitro photothermal heating of HeLa cells in the presence of porous Pd NPs leads to 100% cell death under 808 nm laser irradiation (8 W cm-2, 4 min). For photothermal heating using 730 nm laser, 70% of HeLa cells were killed after 4 min irradiation at a relative low power density of 6 W cm-2. These results demonstrated that the porous Pd nanostructure is an attractive photothermal agent for cancer therapy.Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 107 M-1 cm-1), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water

  6. Alumina-Supported Trirhenium Clusters: Stable High-Temperature Catalysts for Methylcyclohexane Conversion

    SciTech Connect

    Lobo-Lapidus, R.J.; McCall, M.J.; Lanuza, M.; Tonnesen, S.; Bare, S.R.; Gates, B.C.

    2009-05-19

    Samples prepared from H{sub 3}Re{sub 3}(CO){sub 12} adsorbed on porous {gamma}-Al{sub 2}O{sub 3} were decarbonylated at 773 K in flowing H{sub 2} and characterized by X-ray absorption spectroscopy (XAS). X-ray absorption near-edge spectra show that rhenium in the treated sample was cationic, and extended X-ray absorption fine structure spectra show a Re-Re first-shell coordination number of approximately 2, consistent with trirhenium clusters bonded to the support. The samples were tested as catalysts for the conversion of methylcyclohexane in the presence of H{sub 2} at atmospheric pressure and at 723 and at 773 K in a flow reactor. A range of hydrocarbon products was observed, indicating the occurrence of dehydrogenation, isomerization, ring opening, and hydrocracking reactions. The catalyst used at 723 K underwent deactivation over a period of several hours, during which the selectivity for the major dehydrogenation product (toluene) increased significantly. At 773 K, the catalyst underwent activation, during which the product distribution changed. This increase in activity was retained when the temperature was reduced to 723 K, resulting in higher activity and different selectivity relative to what had been observed before at this temperature. The fresh and used catalyst samples were characterized by X-ray absorption spectroscopy, which showed that the trirhenium framework remained intact after catalysis, although changes in the rhenium coordination were observed. The catalytically active species are inferred to be trirhenium.

  7. High voltage-power frequency electrical heating in-situ conversion technology of oil shale

    NASA Astrophysics Data System (ADS)

    Sun, Youhong; Yang, Yang; Lopatin, Vladimir; Guo, Wei; Liu, Baochang; Yu, Ping; Gao, Ke; Ma, Yinlong

    2014-05-01

    With the depletion of conventional energy sources,oil shale has got much attention as a new type of energy resource,which is rich and widespread in the world.The conventional utilization of oil shale is mainly focused on resorting to produce shale oil and fuel gas with low extraction efficiency about one in a million due to many shortcomings and limitations.And the in-situ conversion of oil shale,more environmentally friendly,is still in the experimental stage.High voltage-power frequency electrical heating in-situ conversion of oil shale is a new type of in-situ pyrolysis technology.The main equipment includes a high voltage-power frequency generator and interior reactor. The high voltage-power frequency generator can provide a voltage between 220-8000 V which can be adjusted in real time according to the actual situation.Firstly,high voltage is used to breakdown the oil shale to form a dendritic crack between two electrodes providing a conductive channel inside the oil shale rock.And then the power frequency(220V) is used to generate the electric current for heating the internal surface of conductive channel,so that the energy can be transmitted to the surrounding oil shale.When the temperature reaches 350 degree,the oil shale begins to pyrolysis.In addition,the temperature in the conductive channel can be extremely high with high voltage,which makes the internal surface of conductive channel graphitization and improves its heat conduction performance.This technology can successfully make the oil shale pyrolysis, based on a lot of lab experiments,and also produce the combustible shale oil and fuel gas.Compared to other in-situ conversion technology,this method has the following advantages: high speed of heating oil shale,the equipment underground is simple,and easy to operate;it can proceed without the limitation of shale thickness, and can be used especially in the thin oil shale reservoir;the heating channel is parallel to the oil shale layers,which has more

  8. High-Fidelity Down-Conversion Source for Secure Communications Using On-Demand Single Photons

    NASA Technical Reports Server (NTRS)

    Roberts, Tony

    2015-01-01

    AdvR, Inc., has built an efficient, fully integrated, waveguide-based source of spectrally uncorrelated photon pairs that will accelerate research and development (R&D) in the emerging field of quantum information science. Key to the innovation is the use of submicron periodically poled waveguides to produce counter propagating photon pairs, which is enabled by AdvR's patented segmented microelectrode poling technique. This novel device will provide a high brightness source of down-conversion pairs with enhanced spectral properties and low attenuation, and it will operate in the visible to the mid-infrared spectral region. A waveguide-based source of spectrally and spatially pure heralded photons will contribute to a wide range of NASA's advanced technology development efforts, including on-demand single photon sources for high-rate spaced-based secure communications.

  9. Development of a high-energy distributed energy source electromagnetic railgun with improved energy conversion efficiency

    SciTech Connect

    Tower, M.M.; Haight, C.H.

    1984-03-01

    Vought Corporation in cooperation with the Center for Electromechanics at the University of Texas (CEM-UT) has developed under sponsorship by the Defense Advanced Research Projects Agency (DARPA) and the Army Armament, Munitions, and Chemical Command (AMCCOM) a high-energy distributed energy source (DES) electromagnetic (EM) railgun accelerator. This paper discusses the development and current status of the DES railgun which has the design capability to launch projectile masses up to 60 grams to the 3-4 km/sec velocity regime with energy conversion efficiencies above 35 percent. These goals are being accomplished through utilization of scaled-energy CEM-UT railgun experiments for sequenced timing/staging and a full energy (575 kJ) design at Vought for high efficiency capability. The operational Vought single-pulse railgun forms the baseline for the full energy testing.

  10. Type I parametric down conversion of highly focused Gaussian beams in finite length crystals

    NASA Astrophysics Data System (ADS)

    Jeronimo-Moreno, Yasser; Jáuregui, R.

    2014-06-01

    This paper presents a study of the correlations in wave vector space of photon pairs generated by type I spontaneous parametric down conversion using a Gaussian pump beam. The analysis covers both moderate focused and highly focused regimes, paying special attention to the angular spectrum and the conditional angular spectrum. Simple analytic expressions are derived that allow a detailed study of the dependence of these spectra on the waist of the source and the length of the nonlinear crystal. These expressions are in good agreement with numerical expectations and reported experimental results. They are used to make a systematic search of optimization parameters that improve the feasibility of using highly focused Gaussian beams to generate idler and signal photons with predetermined mean values and spread of their transverse wave vectors.

  11. CMOS highly linear direct-conversion transmitter for WCDMA with fine gain accuracy

    NASA Astrophysics Data System (ADS)

    Xin, Li; Jian, Fu; Yumei, Huang; Zhiliang, Hong

    2011-08-01

    A highly linear, high output power, 0.13 μm CMOS direct conversion transmitter for wideband code division multiple access (WCDMA) is described. The transmitter delivers 6.8 dBm output power with 38 mA current consumption. With careful design on the resistor bank in the IQ-modulator, the gain step accuracy is within 0.1 dB, hence the image rejection ratio can be kept below -47 dBc for the entire output range. The adjacent channel leakage ratio and the LO leakage at 6.8 dBm output power are -44 dBc @ 5 MHz and -37 dBc, respectively, and the corresponding EVM is 3.6%. The overall gain can be programmed in 6 dB steps in a 66-dB range.

  12. Direct-write piezoelectric polymeric nanogenerator with high energy conversion efficiency.

    PubMed

    Chang, Chieh; Tran, Van H; Wang, Junbo; Fuh, Yiin-Kuen; Lin, Liwei

    2010-02-10

    Nanogenerators capable of converting energy from mechanical sources to electricity with high effective efficiency using low-cost, nonsemiconducting, organic nanomaterials are attractive for many applications, including energy harvesters. In this work, near-field electrospinning is used to direct-write poly(vinylidene fluoride) (PVDF) nanofibers with in situ mechanical stretch and electrical poling characteristics to produce piezoelectric properties. Under mechanical stretching, nanogenerators have shown repeatable and consistent electrical outputs with energy conversion efficiency an order of magnitude higher than those made of PVDF thin films. The early onset of the nonlinear domain wall motions behavior has been identified as one mechanism responsible for the apparent high piezoelectricity in nanofibers, rendering them potentially advantageous for sensing and actuation applications.

  13. A One-Dimensional Fluidic Nanogenerator with a High Power Conversion Efficiency.

    PubMed

    Xu, Yifan; Chen, Peining; Zhang, Jing; Xie, Songlin; Wan, Fang; Deng, Jue; Cheng, Xunliang; Hu, Yajie; Liao, Meng; Wang, Bingjie; Sun, Xuemei; Peng, Huisheng

    2017-08-26

    Electricity generation from flowing water has been developed for over a century and plays a critical role in our lives. Generally, heavy and complex facilities are required for electricity generation, while using these technologies for applications that require a small size and high flexibility is difficult. Here, we developed a fluidic nanogenerator fiber from an aligned carbon nanotube sheet to generate electricity from any flowing water source in the environment as well as in the human body. The power conversion efficiency reached 23.3 %. The fluidic nanogenerator fiber was flexible and stretchable, and the high performance was well-maintained after deformation over 1 000 000 cycles. The fiber also offered unique and promising advantages, such as the ability to be woven into fabrics for large-scale applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Potential for efficient frequency conversion at high average power using solid state nonlinear optical materials

    SciTech Connect

    Eimerl, D.

    1985-10-28

    High-average-power frequency conversion using solid state nonlinear materials is discussed. Recent laboratory experience and new developments in design concepts show that current technology, a few tens of watts, may be extended by several orders of magnitude. For example, using KD*P, efficient doubling (>70%) of Nd:YAG at average powers approaching 100 KW is possible; and for doubling to the blue or ultraviolet regions, the average power may approach 1 MW. Configurations using segmented apertures permit essentially unlimited scaling of average power. High average power is achieved by configuring the nonlinear material as a set of thin plates with a large ratio of surface area to volume and by cooling the exposed surfaces with a flowing gas. The design and material fabrication of such a harmonic generator are well within current technology.

  15. High-temperature nuclear closed Brayton cycle power conversion system for the space exploration initiative

    SciTech Connect

    Brandes, D.J. )

    1991-01-05

    The Space Exploration Initiative (SEI) has stated goals of colonizing the moon and conducting manned exploration of the planet Mars. Unlike previous ventures into space, both manned and unmanned, large quantities of electrical power will be required to provide the energy for lunar base sustenance and for highly efficient propulsion systems for the long trip to mars and return. Further, the requirement for electrical power of several megawatts will necessitate the use of nuclear reactor driven power conversion systems. This paper discusses a particle bed reactor closed Brayton cycle space power system that uses advanced materials technology to achieve a high-temperature, low-specific-weight modular system capable of providing the requisite electrical power for both a lunar base and a Mars flight vehicle propulsion system.

  16. High-temperature nuclear closed Brayton cycle power conversion system for the Space Exploration Initiative

    NASA Astrophysics Data System (ADS)

    Brandes, Donald J.

    The Space Exploration Initiative has stated goals of colonizing the moon and conducting manned exploration of the planet Mars. Unlike previous ventures into space, both manned and unmanned, large quantities of electrical power will be required to provide the energy for lunar base sustenance and for highly efficient propulsion systems for the long trip to Mars and return. Further, the requirement for electrical power of several megawatts will necessitate the use of nuclear reactor driven power conversion systems. This paper discusses a particle bed reactor closed Brayton cycle space power system that uses advanced materials technology to achieve a high-temperature, low-specific-weight modular system capable of providing the requisite electrical power for both a lunar base and a Mars flight vehicle propulsion system.

  17. High-temperature nuclear closed Brayton cycle power conversion system for the space exploration initiative

    NASA Astrophysics Data System (ADS)

    Brandes, Donald J.

    1991-01-01

    The Space Exploration Initiative (SEI) has stated goals of colonizing the moon and conducting manned exploration of the planet Mars. Unlike previous ventures into space, both manned and unmanned, large quantities of electrical power will be required to provide the energy for lunar base sustenance and for highly efficient propulsion systems for the long trip to mars and return. Further, the requirement for electrical power of several megawatts will necessitate the use of nuclear reactor driven power conversion systems. This paper discusses a particle bed reactor closed Brayton cycle space power system that uses advanced materials technology to achieve a high-temperature, low-specific-weight modular system capable of providing the requisite electrical power for both a lunar base and a Mars flight vehicle propulsion system.

  18. Brayton Power Conversion Unit Tested: Provides a Path to Future High-Power Electric Propulsion Missions

    NASA Technical Reports Server (NTRS)

    Mason, Lee S.

    2003-01-01

    Closed-Brayton-cycle conversion technology has been identified as an excellent candidate for nuclear electric propulsion (NEP) power conversion systems. Advantages include high efficiency, long life, and high power density for power levels from about 10 kWe to 1 MWe, and beyond. An additional benefit for Brayton is the potential for the alternator to deliver very high voltage as required by the electric thrusters, minimizing the mass and power losses associated with the power management and distribution (PMAD). To accelerate Brayton technology development for NEP, the NASA Glenn Research Center is developing a low-power NEP power systems testbed that utilizes an existing 2- kWe Brayton power conversion unit (PCU) from previous solar dynamic technology efforts. The PCU includes a turboalternator, a recuperator, and a gas cooler connected by gas ducts. The rotating assembly is supported by gas foil bearings and consists of a turbine, a compressor, a thrust rotor, and an alternator on a single shaft. The alternator produces alternating-current power that is rectified to 120-V direct-current power by the PMAD unit. The NEP power systems testbed will be utilized to conduct future investigations of operational control methods, high-voltage PMAD, electric thruster interactions, and advanced heat rejection techniques. The PCU was tested in Glenn s Vacuum Facility 6. The Brayton PCU was modified from its original solar dynamic configuration by the removal of the heat receiver and retrofitting of the electrical resistance gas heater to simulate the thermal input of a steady-state nuclear source. Then, the Brayton PCU was installed in the 3-m test port of Vacuum Facility 6, as shown. A series of tests were performed between June and August of 2002 that resulted in a total PCU operational time of about 24 hr. An initial test sequence on June 17 determined that the reconfigured unit was fully operational. Ensuing tests provided the operational data needed to characterize PCU

  19. High power densities from high-temperature material interactions. [in thermionic energy conversion and metallic fluid heat pipes

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1981-01-01

    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs), offering unique advantages in terrestrial and space energy processing by virtue of operating on working-fluid vaporization/condensation cycles that accept great thermal power densities at high temperatures, share complex materials problems. Simplified equations are presented that verify and solve such problems, suggesting the possibility of cost-effective applications in the near term for TEC and MFHP devices. Among the problems discussed are: the limitation of alkali-metal corrosion, protection against hot external gases, external and internal vaporization, interfacial reactions and diffusion, expansion coefficient matching, and creep deformation.

  20. High power densities from high-temperature material interactions. [in thermionic energy conversion and metallic fluid heat pipes

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1981-01-01

    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs), offering unique advantages in terrestrial and space energy processing by virtue of operating on working-fluid vaporization/condensation cycles that accept great thermal power densities at high temperatures, share complex materials problems. Simplified equations are presented that verify and solve such problems, suggesting the possibility of cost-effective applications in the near term for TEC and MFHP devices. Among the problems discussed are: the limitation of alkali-metal corrosion, protection against hot external gases, external and internal vaporization, interfacial reactions and diffusion, expansion coefficient matching, and creep deformation.

  1. Development of CFD models to support LEU Conversion of ORNL s High Flux Isotope Reactor

    SciTech Connect

    Khane, Vaibhav B; Jain, Prashant K; Freels, James D

    2012-01-01

    The US Department of Energy s National Nuclear Security Administration (NNSA) is participating in the Global Threat Reduction Initiative to reduce and protect vulnerable nuclear and radiological materials located at civilian sites worldwide. As an integral part of one of NNSA s subprograms, Reduced Enrichment for Research and Test Reactors, HFIR is being converted from the present HEU core to a low enriched uranium (LEU) core with less than 20% of U-235 by weight. Because of HFIR s importance for condensed matter research in the United States, its conversion to a high-density, U-Mo-based, LEU fuel should not significantly impact its existing performance. Furthermore, cost and availability considerations suggest making only minimal changes to the overall HFIR facility. Therefore, the goal of this conversion program is only to substitute LEU for the fuel type in the existing fuel plate design, retaining the same number of fuel plates, with the same physical dimensions, as in the current HFIR HEU core. Because LEU-specific testing and experiments will be limited, COMSOL Multiphysics was chosen to provide the needed simulation capability to validate against the HEU design data and previous calculations, and predict the performance of the proposed LEU fuel for design and safety analyses. To achieve it, advanced COMSOL-based multiphysics simulations, including computational fluid dynamics (CFD), are being developed to capture the turbulent flows and associated heat transfer in fine detail and to improve predictive accuracy [2].

  2. Bioreactors for lignocellulose conversion into fermentable sugars for production of high added value products.

    PubMed

    Liguori, Rossana; Ventorino, Valeria; Pepe, Olimpia; Faraco, Vincenza

    2016-01-01

    Lignocellulosic biomasses derived from dedicated crops and agro-industrial residual materials are promising renewable resources for the production of fuels and other added value bioproducts. Due to the tolerance to a wide range of environments, the dedicated crops can be cultivated on marginal lands, avoiding conflict with food production and having beneficial effects on the environment. Besides, the agro-industrial residual materials represent an abundant, available, and cheap source of bioproducts that completely cut out the economical and environmental issues related to the cultivation of energy crops. Different processing steps like pretreatment, hydrolysis and microbial fermentation are needed to convert biomass into added value bioproducts. The reactor configuration, the operative conditions, and the operation mode of the conversion processes are crucial parameters for a high yield and productivity of the biomass bioconversion process. This review summarizes the last progresses in the bioreactor field, with main attention on the new configurations and the agitation systems, for conversion of dedicated energy crops (Arundo donax) and residual materials (corn stover, wheat straw, mesquite wood, agave bagasse, fruit and citrus peel wastes, sunflower seed hull, switchgrass, poplar sawdust, cogon grass, sugarcane bagasse, sunflower seed hull, and poplar wood) into sugars and ethanol. The main novelty of this review is its focus on reactor components and properties.

  3. Alcohol confounds relationship between cannabis misuse and psychosis conversion in a high-risk sample

    PubMed Central

    Auther, A. M.; Cadenhead, K. S.; Carrión, R. E.; Addington, J.; Bearden, C. E.; Cannon, T. D.; McGlashan, T. H.; Perkins, D. O.; Seidman, L.; Tsuang, M.; Walker, E. F.; Woods, S. W.; Cornblatt, B. A.

    2015-01-01

    Objective Cannabis use has been examined as a predictor of psychosis in clinical high-risk (CHR) samples, but little is known about the impact of other substances on this relationship. Method Substance use was assessed in a large sample of CHR participants (N = 370, mean age = 18.3) enrolled in the multisite North American Prodrome Longitudinal Study Phase 1 project. Three hundred and forty-one participants with cannabis use data were divided into groups: No Use (NU, N = 211); Cannabis Use without impairment (CU, N = 63); Cannabis Abuse/Dependence (CA/CD, N = 67). Participants (N = 283) were followed for ≥2 years to determine psychosis conversion. Results Alcohol (45.3%) and cannabis (38.1%) were the most common substances. Cannabis use groups did not differ on baseline attenuated positive symptoms. Seventy-nine of 283 participants with cannabis and follow-up data converted to psychosis. Survival analysis revealed significant differences between conversion rates in the CA/CD group compared with the No Use (P = 0.031) and CU group (P = 0.027). CA/CD also significantly predicted psychosis in a regression analysis, but adjusting for alcohol use weakened this relationship. Conclusion The cannabis misuse and psychosis association was confounded by alcohol use. Non-impairing cannabis use was not related to psychosis. Results highlight the need to control for other substance use, so as to not overstate the cannabis/psychosis connection. PMID:25572323

  4. Very-high-frequency dc-to-dc conversion and regulation in the low-megahertz range.

    NASA Technical Reports Server (NTRS)

    Feng, S. Y. M.; Wilson, T. G.; Sander, W. A., III

    1971-01-01

    Anticipated new mission requirements have motivated research on very-high-frequency (VHF) regulated dc-to-dc converters to operate at conversion frequencies in the low-megahertz range. State-of-the-art electronic components for VHF operation are discussed. Two different converter configurations, one using proportional control and having a conversion frequency of 0.1 MHz and the other using bistable control and having a conversion frequency of 3.8 MHz, are presented to indicate converter performance in this VHF region. Converter losses, which are of prime importance at these frequencies, are discussed and possible means of reducing these losses are suggested.

  5. Selection Practices in American High Schools.

    ERIC Educational Resources Information Center

    Rosenbaum, James E.

    This paper studies two kinds of selection practices in schools, curriculum tracking and class ranking. Using multiple regression analyses of the National Longitudinal Survey (NLS), this paper finds that tracking and class ranks have important effects on whether students can attend college. However, it also finds that many students misperceive…

  6. Soft Magnetic Materials in High-Frequency, High-Power Conversion Applications

    SciTech Connect

    Leary, AM; Ohodnicki, PR; McHenry, ME

    2012-07-04

    Advanced soft magnetic materials are needed to match high-power density and switching frequencies made possible by advances in wide band-gap semiconductors. Magnetics capable of operating at higher operating frequencies have the potential to greatly reduce the size of megawatt level power electronics. In this article, we examine the role of soft magnetic materials in high-frequency power applications and we discuss current material's limitations and highlight emerging trends in soft magnetic material design for high-frequency and power applications using the materials paradigm of synthesis -> structure -> property -> performance relationships.

  7. Selection of the Strain Lactobacillus acidophilus ATCC 43121 and Its Application to Brewers' Spent Grain Conversion into Lactic Acid

    PubMed Central

    Liguori, Rossana; Soccol, Carlos Ricardo; Vandenberghe, Luciana Porto de Souza; Woiciechowski, Adenise Lorenci; Ionata, Elena; Marcolongo, Loredana; Faraco, Vincenza

    2015-01-01

    Six Lactobacillus strains were analyzed to select a bacterium for conversion of brewers' spent grain (BSG) into lactic acid. Among the investigated strains, L. acidophilus ATCC 43121 showed the highest yield of lactic acid production (16.1 g/L after 48 hours) when grown in a synthetic medium. It was then analyzed for its ability to grow on the hydrolysates obtained from BSG after acid-alkaline (AAT) or aqueous ammonia soaking (AAS) pretreatment. The lactic acid production by L. acidophilus ATCC 43121 through fermentation of the hydrolysate from AAS treated BSG was 96% higher than that from the AAT treated one, although similar yields of lactic acid per consumed glucose were achieved due to a higher (46%) glucose consumption by L. acidophilus ATCC 43121 in the AAS BSG hydrolysate. It is worth noting that adding yeast extract to the BSG hydrolysates increased both the yield of lactic acid per substrate consumed and the volumetric productivity. The best results were obtained by fermentation of AAS BSG hydrolysate supplemented by yeast extract, in which the strain produced 22.16 g/L of lactic acid (yield of 0.61 g/g), 27% higher than the value (17.49 g/L) obtained in the absence of a nitrogen source. PMID:26640784

  8. Selection of the Strain Lactobacillus acidophilus ATCC 43121 and Its Application to Brewers' Spent Grain Conversion into Lactic Acid.

    PubMed

    Liguori, Rossana; Soccol, Carlos Ricardo; Vandenberghe, Luciana Porto de Souza; Woiciechowski, Adenise Lorenci; Ionata, Elena; Marcolongo, Loredana; Faraco, Vincenza

    2015-01-01

    Six Lactobacillus strains were analyzed to select a bacterium for conversion of brewers' spent grain (BSG) into lactic acid. Among the investigated strains, L. acidophilus ATCC 43121 showed the highest yield of lactic acid production (16.1 g/L after 48 hours) when grown in a synthetic medium. It was then analyzed for its ability to grow on the hydrolysates obtained from BSG after acid-alkaline (AAT) or aqueous ammonia soaking (AAS) pretreatment. The lactic acid production by L. acidophilus ATCC 43121 through fermentation of the hydrolysate from AAS treated BSG was 96% higher than that from the AAT treated one, although similar yields of lactic acid per consumed glucose were achieved due to a higher (46%) glucose consumption by L. acidophilus ATCC 43121 in the AAS BSG hydrolysate. It is worth noting that adding yeast extract to the BSG hydrolysates increased both the yield of lactic acid per substrate consumed and the volumetric productivity. The best results were obtained by fermentation of AAS BSG hydrolysate supplemented by yeast extract, in which the strain produced 22.16 g/L of lactic acid (yield of 0.61 g/g), 27% higher than the value (17.49 g/L) obtained in the absence of a nitrogen source.

  9. The selective catalytic cracking of Fischer-Tropsch liquids to high value transportation fuels. Final report

    SciTech Connect

    Schwartz, M.M.; Reagon, W.J.; Nicholas, J.J.; Hughes, R.D.

    1994-11-01

    Amoco Oil Company, investigated a selective catalytic cracking process (FCC) to convert the Fischer-Tropsch (F-T) gasoline and wax fractions to high value transportation fuels. The primary tasks of this contract were to (1) optimize the catalyst and process conditions of the FCC process for maximum conversion of F-T wax into reactive olefins for later production of C{sub 4}{minus}C{sub 8} ethers, and (2) use the olefin-containing light naphtha obtained from FCC processing of the F-T wax as feedstock for the synthesis of ethers. The catalytic cracking of F-T wax feedstocks gave high conversions with low activity catalysts and low process severities. HZSM-5 and beta zeolite catalysts gave higher yields of propylene, isobutylene, and isoamylenes but a lower gasoline yield than Y zeolite catalysts. Catalyst selection and process optimization will depend on product valuation. For a given catalyst and process condition, Sasol and LaPorte waxes gave similar conversions and product selectivities. The contaminant iron F-T catalyst fines in the LaPorte wax caused higher coke and hydrogen yields.

  10. Conversion of high explosive chemical energy into energy of powerful nanosecond high-current pulses

    NASA Astrophysics Data System (ADS)

    Gorbachev, K. V.; Mikhaylov, V. M.; Nesterov, E. V.; Stroganov, V. A.; Chernykh, E. V.

    2015-01-01

    This study is a contribution into the development of physicotechnical foundations for generation of powerful nanosecond high-current pulses on the basis of explosively driven magnetic flux compression generators. This problem is solved by using inductive storage of energy for matching comparatively low-voltage explosively driven magnetic flux compression generators and high-impedance loads; short forming lines and vacuum diodes. Experimental data of charging of forming lines are given.

  11. High-fidelity frequency down-conversion of visible entangled photon pairs with superconducting single-photon detectors

    SciTech Connect

    Ikuta, Rikizo; Kato, Hiroshi; Kusaka, Yoshiaki; Yamamoto, Takashi; Imoto, Nobuyuki; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Wang, Zhen; Fujiwara, Mikio; Sasaki, Masahide; Koashi, Masato

    2014-12-04

    We experimentally demonstrate a high-fidelity visible-to-telecommunicationwavelength conversion of a photon by using a solid-state-based difference frequency generation. In the experiment, one half of a pico-second visible entangled photon pair at 780 nm is converted to a 1522-nm photon. Using superconducting single-photon detectors with low dark count rates and small timing jitters, we observed a fidelity of 0.93±0.04 after the wavelength conversion.

  12. High performance materials in coal conversion utilization. Technical progress report, April 1, 1995--June 30, 1995

    SciTech Connect

    1995-07-01

    This is the seventh quarterly report on a three year grant regarding {open_quotes}High Performance Materials in Coal Conversion Utilization.{close_quotes} The grant is for a joint university/industry effort under the US Department of Energy (DOE) University Coal Research Program. The University of Tennessee Space Institute (UTSI) is the prime contractor and The University of Pennsylvania and Lanxide Corporation are subcontractors. UTSI has completed the planned laboratory exposure tests involving pulverized coal slag on the production of Lanxide DIMOX{trademark} ceramic composite material. In addition, the strength testing (at temperature) of C-ring sections of the production composite is complete and the analysis of the data is reported in a thesis which was submitted toward a M.S. degree.

  13. High performance materials in coal conversion utilization. Technical progress report, October 1, 1995--December 31, 1995

    SciTech Connect

    1996-01-01

    This is the ninth quarterly report on a three year grant regarding {open_quotes}High Performance Materials in Coal Conversion Utilization.{close_quotes} The grant is for a joint university/industry effort under the U.S. Department of Energy (DOE) University Coal Research Program. The University of Tennessee Space Institute (UTSI) is the prime contractor and The University of Pennsylvania and Lanxide Corporation are subcontractors. UTSI has completed all the initially planned laboratory exposure tests involving pulverized coal slag on the production Lanxide DIMOX{trademark} ceramic composite material. In addition, the strength testing (at temperature) and analysis of C-ring sections of the exposed production composite is complete. The development of a technique to laser coat the material has been the major activity while awaiting an innovatively produced new test sample. This sample will be tested and compared to the production tubes tested at UTSI.

  14. A neutronic feasibility study for LEU conversion of the high flux isotope reactor (HFIR).

    SciTech Connect

    Mo, S. C.

    1998-01-14

    A neutronic feasibility study was performed to determine the uranium densities that would be required to convert the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) from HEU (93%) to LEU (<20%)fuel. The LEU core that was studied is the same as the current HEU core, except for potential changes in the design of the fuel plates. The study concludes that conversion of HFIR from HEU to LEU fuel would require an advanced fuel with a uranium density of 6-7 gU/cm{sup 3} in the inner fuel element and 9-10 gU/cm{sup 3} in the outer fuel element to match the cycle length of the HEU core. LEU fuel with uranium density up to 4.8 gU/cm{sup 3} is currently qualified for research reactor use. Modifications in fuel grading and burnable poison distribution are needed to produce an acceptable power distribution.

  15. Large Seebeck coefficients of protonated titanate nanotubes for high-temperature thermoelectric conversion.

    PubMed

    Miao, L; Tanemura, S; Huang, R; Liu, C Y; Huang, C M; Xu, G

    2010-08-01

    Titanate nanotubes Na(2-x)H(x)Ti(3)O(7) produced by alkali hydrothermally treated ground TiO(2) aerogels are investigated as possible materials for high-temperature thermoelectric conversion by measuring their thermoelectric properties. Strikingly, the Seebeck coefficients increased sharply in the temperature range 745 to 1032 K, reaching a maximum of 302 muV/K. The electrical resistivity of the TNNTs ranged from 325 to 525 Omegam, which is lower than that of bulk TiO(2), and thermal conductivities at room temperature were also very low, ranging from 0.55 to 0.75 Wm(-1) K(-1). The hollow structure of the titanate nanotubes, with small, uniform diameters, is thought to be responsible for the ultralow thermal conductivity. The large thermoelectric power and ultralow thermal conductivity suggest that titanate nanotubes represent a new kind of p-type oxide thermoelectric material.

  16. Cake And Conversation: the women's jour in Parisian high society, 1880-1914.

    PubMed

    Macknight, Elizabeth C

    2005-01-01

    At the end of the nineteenth century an upper-class Parisian hostess invited guests into her home on a fixed afternoon of her choice each week. Was this tradition, known as the jour, merely an occasion to partake of refreshments and chat? Or did it serve broader purposes for the women of High Society? This article investigates the process of invitation to a jour, the subtle nuances of etiquette at these gatherings, conversation between men and women, and what was consumed in the way of food and drink. By documenting social interaction in the space of the salon, this article analyses the way in which "power" was constituted through bodily practices. It then goes on to show what the exercise of this power reveals about gender roles, and the structure of social relationships among the Parisian upper class, in the decades before the First World War.

  17. Effect of X-ray High-voltage Variations on the Conversion Coefficients.

    PubMed

    Behnke, B; Hupe, O; Behrens, R

    2016-10-20

    Conversion coefficients (CCs) are an essential vehicle in radiation protection for the determination of the dose (rate) of a given radiation field. According to the current draft of the revision of international standard ISO 4037, an X-ray field is a reference field if the CCs of the field match the tabulated ISO values within 2%. Deviations of the high-voltage (HV) tube-potential from its nominal value influence the resulting spectra and change the corresponding CCs. This work investigates the maximum allowable deviation of the HV from its nominal value such that the requirements of ISO 4037 remain fulfilled. This is achieved using both synthetic spectra created by a software simulation program and spectra measured at one of the X-ray facilities of the Physikalisch-Technische Bundesanstalt. The results are summarised in form of a new proposal for upper limit values which are suggested to be used in the next version of ISO 4037.

  18. Morphological Factor Estimation via High-Dimensional Reduction: Prediction of MCI Conversion to Probable AD

    PubMed Central

    Duchesne, Simon; Mouiha, Abderazzak

    2011-01-01

    We propose a novel morphological factor estimate from structural MRI for disease state evaluation. We tested this methodology in the context of Alzheimer's disease (AD) with 349 subjects. The method consisted in (a) creating a reference MRI feature eigenspace using intensity and local volume change data from 149 healthy, young subjects; (b) projecting MRI data from 75 probable AD, 76 controls (CTRL), and 49 Mild Cognitive Impairment (MCI) in that space; (c) extracting high-dimensional discriminant functions; (d) calculating a single morphological factor based on various models. We used this methodology in leave-one-out experiments to (1) confirm the superiority of an inverse-squared model over other approaches; (2) obtain accuracy estimates for the discrimination of probable AD from CTRL (90%) and the prediction of conversion of MCI subjects to probable AD (79.4%). PMID:21755033

  19. Report of feasibility study on international-cooperation in high efficient energy conversion technology

    NASA Astrophysics Data System (ADS)

    1993-03-01

    With regard to accelerated introduction of high efficient energy conversion technology to developing countries, the paper investigates the countries' thoughts of the introduction of the technology and the status of the introduction bases. The countries for survey are the Philippines, Indonesia, Malaysia and Thailand. The Philippine government expects to develop cogeneration as well as large power sources and to widen effective use of natural energy. In Indonesia, they largely expect effective use of biomass energy using Stirling engines by international cooperation and the promoted local electrification using standalone distributed fuel cells. In Malaysia, they have great expectations of the introduction of air conditioning facilities using Stirling engines and the use of standalone distributed fuel cells for promotion of local electrification. Thailand hopes for the use of Stirling engines to air conditioning systems, and the development of solar Stirling generators with solar energy as a heat source and electric vehicles.

  20. High efficiency carrier multiplication in PbSe nanocrystals: implications for solar energy conversion.

    PubMed

    Schaller, R D; Klimov, V I

    2004-05-07

    We demonstrate for the first time that impact ionization (II) (the inverse of Auger recombination) occurs with very high efficiency in semiconductor nanocrystals (NCs). Interband optical excitation of PbSe NCs at low pump intensities, for which less than one exciton is initially generated per NC on average, results in the formation of two or more excitons (carrier multiplication) when pump photon energies are more than 3 times the NC band gap energy. The generation of multiexcitons from a single photon absorption event is observed to take place on an ultrafast (picosecond) time scale and occurs with up to 100% efficiency depending upon the excess energy of the absorbed photon. Efficient II in NCs can be used to considerably increase the power conversion efficiency of NC-based solar cells.

  1. A Techno-Economic Optimization of the Power Conversion System of a Very High Temperature Reactor

    SciTech Connect

    Mansilla, Christine; Dumas, Michel; Werkoff, Francois

    2006-07-01

    Generation IV nuclear reactors will not be implemented unless they enable lower production costs than with the current systems. In such a context a techno-economic optimization method was developed and then applied to the power conversion system of a very high temperature reactor. Techno-economic optimization consists in minimizing an objective function that depends on technical variables and economic ones. The advantage of the techno-economic optimization is that it can take into account both investment costs and operating costs. A techno-economic model was implemented in a specific optimization software named Vizir, which is based on genetic algorithms. The calculation of the thermodynamic cycle is performed by a software named Tugaz. The results are the values of the decision variables that lead to a minimum cost, according to the model. The total production cost is evaluated. The influence of the various variables and constraints is also pointed out. (authors)

  2. Highly efficient direct conversion of human fibroblasts to neuronal cells by chemical compounds.

    PubMed

    Dai, Ping; Harada, Yoshinori; Takamatsu, Tetsuro

    2015-05-01

    Direct conversion of mammalian fibroblasts into induced neuronal (iN) cells has been attained by forced expression of pro-neural transcriptional factors, or by combining defined factors with either microRNAs or small molecules. Here, we show that neuronal cells can be converted from postnatal human fibroblasts into cell populations with neuronal purities of up to >80% using a combination of six chemical compounds. The chemical compound-induced neuronal cells (CiNCs) express neuron-specific proteins and functional neuron markers. The efficiency of CiNCs is unaffected by either the donor's age or cellular senescence (passage number). We propose this chemical direct converting strategy as a potential approach for highly efficient generation of neuronal cells from human fibroblasts for such uses as in neural disease modeling and regenerative medicine.

  3. Selective conversion of polyenes to monoenes by RuCl(3) -catalyzed transfer hydrogenation: the case of cashew nutshell liquid.

    PubMed

    Perdriau, Sébastien; Harder, Sjoerd; Heeres, Hero J; de Vries, Johannes G

    2012-12-01

    Cardanol, a constituent of cashew nutshell liquid (CNSL), was subjected to transfer hydrogenation catalyzed by RuCl(3) using isopropanol as a reductant. The side chain of cardanol, which is a mixture of a triene, a diene, and a monoene, was selectively reduced to the monoene. Surprisingly, it is the C8-C9 double bond that is retained with high selectivity. A similar transfer hydrogenation of linoleic acid derivatives succeeded only if the substrate contained an aromatic ring, such as a benzyl ester. TEM and a negative mercury test showed that the catalyst was homogeneous. By using ESI-MS, ruthenium complexes were identified that contained one, two, or even three molecules of substrate, most likely as allyl complexes. The interaction between ruthenium and the aromatic ring determines selectivity in the hydrogenation reaction.

  4. The Impact of Laws on Metric Conversion. A Survey of Selected Large U.S. Corporations. Final Report.

    ERIC Educational Resources Information Center

    Newman & Hermanson Co., Washington, DC.

    This study was conducted to determine the extent to which a sample of 51 Fortune 1000 firms perceive that legal impediments to metric conversion exist. The seven major findings were: (1) laws and regulations are not meaningful impediments to metric conversion, but certain ones must be considered in the planning process; (2) the laws of concern are…

  5. The Impact of Laws on Metric Conversion. A Survey of Selected Large U.S. Corporations. Final Report.

    ERIC Educational Resources Information Center

    Newman & Hermanson Co., Washington, DC.

    This study was conducted to determine the extent to which a sample of 51 Fortune 1000 firms perceive that legal impediments to metric conversion exist. The seven major findings were: (1) laws and regulations are not meaningful impediments to metric conversion, but certain ones must be considered in the planning process; (2) the laws of concern are…

  6. Highly Selective Oxidation of Carbohydrates in an Efficient Electrochemical Energy Converter: Cogenerating Organic Electrosynthesis.

    PubMed

    Holade, Yaovi; Servat, Karine; Napporn, Teko W; Morais, Cláudia; Berjeaud, Jean-Marc; Kokoh, Kouakou B

    2016-02-08

    The selective electrochemical conversion of highly functionalized organic molecules into electricity, heat, and added-value chemicals for fine chemistry requires the development of highly selective, durable, and low-cost catalysts. Here, we propose an approach to make catalysts that can convert carbohydrates into chemicals selectively and produce electrical power and recoverable heat. A 100% Faradaic yield was achieved for the selective oxidation of the anomeric carbon of glucose and its related carbohydrates (C1-position) without any function protection. Furthermore, the direct glucose fuel cell (DGFC) enables an open-circuit voltage of 1.1 V in 0.5 m NaOH to be reached, a record. The optimized DGFC delivers an outstanding output power Pmax =2 mW cm(-2) with the selective conversion of 0.3 m glucose, which is of great interest for cogeneration. The purified reaction product will serve as a raw material in various industries, which thereby reduces the cost of the whole sustainable process.

  7. Investigation of Material Problems for High Temperature, High Power Space Energy-Conversion Systems

    DTIC Science & Technology

    1985-01-01

    tungsten . F.E. Scyeryenie [4.42) and H.C. Rogers studied the effects of hydrogen *) embrittlement of tungsten base heavy alloys ...accumulation of a critical amount in the highly stressed region ahead of the notch. As we are studying tungsten base heavy alloys and as it. has been...Intergranular brittleness studies In Tungsten using Auger spectroscopy , Metallurgical transactions, Vol. 1, Sept. 1970, pg. 2543. 14.40 Ronald P.

  8. Ultra-broad band, low power, highly efficient coherent wavelength conversion in quantum dot SOA.

    PubMed

    Contestabile, G; Yoshida, Y; Maruta, A; Kitayama, K

    2012-12-03

    We report broadband, all-optical wavelength conversion over 100 nm span, in full S- and C-band, with positive conversion efficiency with low optical input power exploiting dual pump Four-Wave-Mixing in a Quantum Dot Semiconductor Optical Amplifier (QD-SOA). We also demonstrate by Error Vector Magnitude analysis the full transparency of the conversion scheme for coherent modulation formats (QPSK, 8-PSK, 16-QAM, OFDM-16QAM) in the whole C-band.

  9. High-quality LaVO3 films as solar energy conversion material

    DOE PAGES

    Zhang, Hai -Tian; Brahlek, Matthew; Ji, Xiaoyu; ...

    2017-03-21

    Mott insulating oxides and their heterostructures have recently been identified as potential photovoltaic materials with favorable absorption properties and an intrinsic built-in electric field that can efficiently separate excited electron hole pairs. At the same time, they are predicted to overcome the Shockley-Queisser limit due to strong electron electron interaction present. Despite these premises a high concentration of defects commonly observed in Mott insulating films acting as recombination centers can derogate the photovoltaic conversion efficiency. With use of the self-regulated growth kinetics in hybrid molecular beam epitaxy, this obstacle can be overcome. High-quality, stoichiometric LaVO3 films were grown with defectmore » densities of in-gap states up to 2 orders of magnitude lower compared to the films in the literature, and a factor of 3 lower than LaVO3 bulk single crystals. Photoconductivity measurements revealed a significant photoresponsivity increase as high as tenfold of stoichiometric LaVO3 films compared to their nonstoichiometric counterparts. Furthermore, this work marks a critical step toward the realization of high-performance Mott insulator solar cells beyond conventional semiconductors.« less

  10. High-Quality LaVO3 Films as Solar Energy Conversion Material.

    PubMed

    Zhang, Hai-Tian; Brahlek, Matthew; Ji, Xiaoyu; Lei, Shiming; Lapano, Jason; Freeland, John W; Gopalan, Venkatraman; Engel-Herbert, Roman

    2017-04-12

    Mott insulating oxides and their heterostructures have recently been identified as potential photovoltaic materials with favorable absorption properties and an intrinsic built-in electric field that can efficiently separate excited electron-hole pairs. At the same time, they are predicted to overcome the Shockley-Queisser limit due to strong electron-electron interaction present. Despite these premises a high concentration of defects commonly observed in Mott insulating films acting as recombination centers can derogate the photovoltaic conversion efficiency. With use of the self-regulated growth kinetics in hybrid molecular beam epitaxy, this obstacle can be overcome. High-quality, stoichiometric LaVO3 films were grown with defect densities of in-gap states up to 2 orders of magnitude lower compared to the films in the literature, and a factor of 3 lower than LaVO3 bulk single crystals. Photoconductivity measurements revealed a significant photoresponsivity increase as high as tenfold of stoichiometric LaVO3 films compared to their nonstoichiometric counterparts. This work marks a critical step toward the realization of high-performance Mott insulator solar cells beyond conventional semiconductors.

  11. Highly Selective Photothermal Therapy by a Phenoxylated-Dextran-Functionalized Smart Carbon Nanotube Platform.

    PubMed

    Han, Seungmin; Kwon, Taeyun; Um, Jo-Eun; Haam, Seungjoo; Kim, Woo-Jae

    2016-05-01

    Near-infrared (NIR) photothermal therapy using biocompatible single-walled carbon nanotubes (SWNTs) is advantageous because as-produced SWNTs, without additional size control, both efficiently absorb NIR light and demonstrate high photothermal conversion efficiency. In addition, covalent attachment of receptor molecules to SWNTs can be used to specifically target infected cells. However, this technique interrupts SWNT optical properties and inevitably lowers photothermal conversion efficiency and thus remains major hurdle for SWNT applications. This paper presents a smart-targeting photothermal therapy platform for inflammatory disease using newly developed phenoxylated-dextran-functionalized SWNTs. Phenoxylated dextran is biocompatible and efficiently suspends SWNTs by noncovalent π-π stacking, thereby minimizing SWNT bundle formations and maintaining original SWNT optical properties. Furthermore, it selectively targets inflammatory macrophages by scavenger-receptor binding without any additional receptor molecules; therefore, its preparation is a simple one-step process. Herein, it is experimentally demonstrated that phenoxylated dextran-SWNTs (pD-SWNTs) are also biocompatible, selectively penetrate inflammatory macrophages over normal cells, and exhibit high photothermal conversion efficiency. Consequently, NIR laser-triggered macrophage treatment can be achieved with high accuracy by pD-SWNT without damaging receptor-free cells. These smart targeting materials can be a novel photothermal agent candidate for inflammatory disease.

  12. Automatic conversational scene analysis in children with Asperger syndrome/high-functioning autism and typically developing peers.

    PubMed

    Tavano, Alessandro; Pesarin, Anna; Murino, Vittorio; Cristani, Marco

    2014-01-01

    Individuals with Asperger syndrome/High Functioning Autism fail to spontaneously attribute mental states to the self and others, a life-long phenotypic characteristic known as mindblindness. We hypothesized that mindblindness would affect the dynamics of conversational interaction. Using generative models, in particular Gaussian mixture models and observed influence models, conversations were coded as interacting Markov processes, operating on novel speech/silence patterns, termed Steady Conversational Periods (SCPs). SCPs assume that whenever an agent's process changes state (e.g., from silence to speech), it causes a general transition of the entire conversational process, forcing inter-actant synchronization. SCPs fed into observed influence models, which captured the conversational dynamics of children and adolescents with Asperger syndrome/High Functioning Autism, and age-matched typically developing participants. Analyzing the parameters of the models by means of discriminative classifiers, the dialogs of patients were successfully distinguished from those of control participants. We conclude that meaning-free speech/silence sequences, reflecting inter-actant synchronization, at least partially encode typical and atypical conversational dynamics. This suggests a direct influence of theory of mind abilities onto basic speech initiative behavior.

  13. Automatic Conversational Scene Analysis in Children with Asperger Syndrome/High-Functioning Autism and Typically Developing Peers

    PubMed Central

    Tavano, Alessandro; Pesarin, Anna; Murino, Vittorio; Cristani, Marco

    2014-01-01

    Individuals with Asperger syndrome/High Functioning Autism fail to spontaneously attribute mental states to the self and others, a life-long phenotypic characteristic known as mindblindness. We hypothesized that mindblindness would affect the dynamics of conversational interaction. Using generative models, in particular Gaussian mixture models and observed influence models, conversations were coded as interacting Markov processes, operating on novel speech/silence patterns, termed Steady Conversational Periods (SCPs). SCPs assume that whenever an agent's process changes state (e.g., from silence to speech), it causes a general transition of the entire conversational process, forcing inter-actant synchronization. SCPs fed into observed influence models, which captured the conversational dynamics of children and adolescents with Asperger syndrome/High Functioning Autism, and age-matched typically developing participants. Analyzing the parameters of the models by means of discriminative classifiers, the dialogs of patients were successfully distinguished from those of control participants. We conclude that meaning-free speech/silence sequences, reflecting inter-actant synchronization, at least partially encode typical and atypical conversational dynamics. This suggests a direct influence of theory of mind abilities onto basic speech initiative behavior. PMID:24489674

  14. Investigation of the Performance of D2O-Cooled High-Conversion Reactors for Fuel Cycle Calculations

    SciTech Connect

    Hikaru Hiruta; Gilles Youinou

    2013-09-01

    This report presents FY13 activities for the analysis of D2O cooled tight-pitch High-Conversion PWRs (HCPWRs) with U-Pu and Th-U fueled cores aiming at break-even or near breeder conditions while retaining the negative void reactivity. The analyses are carried out from several aspects which could not be covered in FY12 activities. SCALE 6.1 code system is utilized, and a series of simple 3D fuel pin-cell models are developed in order to perform Monte Carlo based criticality and burnup calculations. The performance of U-Pu fueled cores with axial and internal blankets is analyzed in terms of their impact on the relative fissile Pu mass balance, initial Pu enrichment, and void coefficient. In FY12, Pu conversion performances of D2O-cooled HCPWRs fueled with MOX were evaluated with small sized axial/internal DU blankets (approximately 4cm of axial length) in order to ensure the negative void reactivity, which evidently limits the conversion performance of HCPWRs. In this fiscal year report, the axial sizes of DU blankets are extended up to 30 cm in order to evaluate the amount of DU necessary to reach break-even and/or breeding conditions. Several attempts are made in order to attain the milestone of the HCPWR designs (i.e., break-even condition and negative void reactivity) by modeling of HCPWRs under different conditions such as boiling of D2O coolant, MOX with different 235U enrichment, and different target burnups. A similar set of analyses are performed for Th-U fueled cores. Several promising characteristics of 233U over other fissile like 239Pu and 235U, most notably its higher fission neutrons per absorption in thermal and epithermal ranges combined with lower ___ in the fast range than 239Pu allows Th-U cores to be taller than MOX ones. Such an advantage results in 4% higher relative fissile mass balance than that of U-Pu fueled cores while retaining the negative void reactivity until the target burnup of 51 GWd/t. Several other distinctions between U-Pu and

  15. High-rate anaerobic wastewater treatment: diversifying from end-of-the-pipe treatment to resource-oriented conversion techniques.

    PubMed

    van Lier, Jules B

    2008-01-01

    Decades of developments and implementations in the field of high-rate anaerobic wastewater treatment have put the technology at a competitive level. With respect to sustainability and cost-effectiveness, anaerobic treatment has a much better score than many alternatives. Particularly, the energy conservation aspect, i.e. avoiding the loss of energy for destruction of organic matter, while energy is reclaimed from the organic waste constituents in the form of biogas, was an important driver in the development of such systems. Invoked by the present greenhouse alert, the energy involved is nowadays translated into carbon credits, providing another incentive to further implement anaerobic technology. Anaerobic conversion processes, however, offer much more than cost-effective treatment systems. Selective recovery of metals, effective desulphurization, recovery of nutrients, reductive detoxification, and anaerobic oxidation of specific compounds are examples of the potentials of anaerobic treatment. This paper presents a survey on the state of the art of full-scale anaerobic high-rate treatment of industrial wastewaters and highlights current trends in anaerobic developments. (c) IWA Publishing 2008.

  16. Stroke and conversion to high risk in children screened with transcranial Doppler ultrasound during the STOP study.

    PubMed

    Adams, Robert J; Brambilla, Donald J; Granger, Suzanne; Gallagher, Dianne; Vichinsky, Elliott; Abboud, Miguel R; Pegelow, Charles H; Woods, Gerald; Rohde, Elizabeth M; Nichols, Fenwick T; Jones, Anne; Luden, Judith P; Bowman, Latonya; Hagner, Susan; Morales, Knashawn H; Roach, E Steve

    2004-05-15

    The Stroke Prevention Trial in Sickle Cell Anemia (STOP) was a randomized multicenter controlled trial comparing prophylactic blood transfusion with standard care in sickle cell anemia (SCA) children aged 2 to 16 years selected for high stroke risk by transcranial Doppler (TCD). More than 2000 children were screened with TCD to identify the 130 high-risk children who entered the randomized trial. A total of 5613 TCD studies from 2324 children were evaluated. We also collected information on stroke. We describe the changes in TCD with repeated testing and report the outcome without transfusion in the STOP screened cohort. Risk of stroke was higher with abnormal TCD than with normal or conditional TCD (P <.001) or inadequate TCD (P =.002), and risk with conditional TCD was higher than with normal TCD (P <.001). Repeated TCD in 1215 children showed that the condition of 9.4% of children became abnormal during observation. Younger patients and those with higher initial flow velocities were most likely to convert to abnormal TCDs. Screening in STOP confirmed the predictive value of TCD for stroke. Substantial differences in the probability of conversion to abnormal TCD were observed, with younger children and those with higher velocity more likely to have an abnormal TCD with rescreening.

  17. High performance materials in coal conversion utilization. Technical progress report, July 1, 1995--September 30, 1995

    SciTech Connect

    1995-10-01

    This is the eighth quarterly report on a three year grant regarding ``High Performance Materials in Coal Conversion Utilization.`` The grant is for a joint university/industry effort under the US Department of Energy (DOE) University Coal Research Program. The University of Tennessee Space Institute (UTSI) is the prime contractor and the University of Pennsylvania and Lanxide Corporation are subcontractors. The object of this grant is to test, analyze, and improve the heat and coal-slag corrosion resistance of a SiC{sub (p)}/Al{sub 2}O{sub 3} ceramic composite tubular material. The material will be evaluated for its ability to withstand the pressures, temperatures and corrosion attack which would be encountered within a coal-fired high-temperature, high pressure air heater. The evaluation includes strength testing at elevated temperatures of production tubes as well as one manufactured with an innovative new technology. The feasibility of several joining and coating techniques are also being investigated. UTSI has completed all the initially planned laboratory exposure tests involving pulverized coal slag on the production Lanxide DIMOX{trademark} ceramic composite material. In addition, the strength testing (at temperature) and analysis of C- ring sections of the exposed production composite are complete.

  18. High performance materials in coal conversion utilization. Technical progress report, January 1, 1996--March 31, 1996

    SciTech Connect

    1996-04-01

    This is the tenth quarterly report on a three year grant regarding ``High Performance Materials in Coal Conversion Utilization.`` The grant is for a joint university/industry effort under the US Department of Energy (DOE) University Coal Research Program. The University of Tennessee Space Institute (UTSI) is the prime contractor and The University of Pennsylvania and Lanxide Corporation are subcontractors. The object of this grant is to test, analyze, and improve the heat and coal-slag corrosion resistance of a SiC{sub (p)}/Al{sub 2}O{sub 3} ceramic composite tubular material. The material will be evaluated for its ability to withstand the pressures, temperatures and corrosion attack which would be encountered within a coal-fired high-temperature, high pressure air heater. The evaluation includes strength testing at elevated temperatures of production tubes as well as one tube manufactured with an innovative new technology. The feasibility of several joining and coating techniques will also be investigated. UTSI has completed all the initially planned laboratory exposure tests involving pulverized coal slag on the production Lanxide DIMOX{trademark} ceramic composite material. In addition, the strength testing (at temperature) and analysis of C-ring sections of the exposed production composite is complete. The evaluation of a laser-induced coating to laser coat the material has been the major activity this quarter while awaiting an innovatively produced new DIMOX{trademark} test sample.

  19. High-frequency thermal-electrical cycles for pyroelectric energy conversion

    SciTech Connect

    Bhatia, Bikram; Damodaran, Anoop R.; Cho, Hanna; Martin, Lane W.; King, William P.

    2014-11-21

    We report thermal to electrical energy conversion from a 150 nm thick BaTiO{sub 3} film using pyroelectric cycles at 1 kHz. A microfabricated platform enables temperature and electric field control with temporal resolution near 1 μs. The rapid electric field changes as high as 11 × 10{sup 5 }kV/cm-s, and temperature change rates as high as 6 × 10{sup 5 }K/s allow exploration of pyroelectric cycles in a previously unexplored operating regime. We investigated the effect of phase difference between electric field and temperature cycles, and electric field and temperature change rates on the electrical energy generated from thermal-electrical cycles based on the pyroelectric Ericsson cycle. Complete thermodynamic cycles are possible up to the highest cycle rates tested here, and the energy density varies significantly with phase shifts between temperature and electric field waveforms. This work could facilitate the design and operation of pyroelectric cycles at high cycle rates, and aid in the design of new pyroelectric systems.

  20. Eliminating Gene Conversion Improves High-Throughput Genetics in Saccharomyces cerevisiae

    PubMed Central

    Daniel, Jewel A.; Yoo, Jiyoun; Bettinger, Blaine T.; Amberg, David C.; Burke, Daniel J.

    2006-01-01

    Synthetic genetic analysis was improved by eliminating leaky expression of the HIS3 reporter and gene conversion between the HIS3 reporter and his3Δ1. Leaky expression was eliminated using 3-aminotriazole and gene conversion was eliminated by using the Schizosaccharomyces pombe his5+ gene, resulting in a 5- to 10-fold improvement in the efficiency of SGA. PMID:16157664

  1. Eliminating gene conversion improves high-throughput genetics in Saccharomyces cerevisiae.

    PubMed

    Daniel, Jewel A; Yoo, Jiyoun; Bettinger, Blaine T; Amberg, David C; Burke, Daniel J

    2006-01-01

    Synthetic genetic analysis was improved by eliminating leaky expression of the HIS3 reporter and gene conversion between the HIS3 reporter and his3Delta1. Leaky expression was eliminated using 3-aminotriazole and gene conversion was eliminated by using the Schizosaccharomyces pombe his5+ gene, resulting in a 5- to 10-fold improvement in the efficiency of SGA.

  2. Student Selective Series for High School English.

    ERIC Educational Resources Information Center

    Flint Public Schools, MI.

    This English curriculum guide describes over 40 content-centered high school courses grouped according to five difficulty levels for each of which specific reading, writing, listening, and speaking objectives are offered. It is oriented to the interests of students and covers such subject matter areas as Heroes, the Harlem Renaissance, America:…

  3. Conversion of low BMEP 4-cylinder to high BMEP 2-cylinder large bore natural gas engine

    NASA Astrophysics Data System (ADS)

    Ladd, John

    There are more than 6,000 integral compressor engines in use on US natural gas pipelines, operating 24 hours a day, 365 days a year. Many of these engines have operated continuously for more than 50 years, with little to no modifications. Due to recent emission regulations at the local, state and federal levels much of the aging infrastructure requires retrofit technology to remain within compliance. The Engines and Energy Conversion Laboratory was founded to test these retrofit technologies on its large bore engine testbed (LBET). The LBET is a low brake mean effective pressure (BMEP) Cooper Bessemer GMVTF-4. Newer GMV models, constructed in 1980's, utilize turbocharging to increase the output power, achieving BMEP's nearly double that of the LBET. To expand the lab's testing capability and to reduce the LBET's running cost: material testing, in-depth modeling, and on engine testing was completed to evaluate the feasibility of uprating the LBET to a high BMEP two cylinder engine. Due to the LBET's age, the crankcase material properties were not known. Material samples were removed from engine to conduct an in-depth material analysis. It was found that the crankcase was cast out of a specific grade of gray iron, class 25 meehanite. A complete three dimensional model of the LBET's crankcase and power cylinders was created. Using historical engine data, the force inputs were created for a finite element analysis model of the LBET, to determine the regions of high stress. The areas of high stress were instrumented with strain gauges to iterate and validate the model's findings. Several test cases were run at the high and intermediate BMEP engine conditions. The model found, at high BMEP conditions the LBET would operate at the fatigue limit of the class 25 meehanite, operating with no factor of safety but the intermediate case were deemed acceptable.

  4. Feasible conversion of solid waste bauxite tailings into highly crystalline 4A zeolite with valuable application.

    PubMed

    Ma, Dongyang; Wang, Zhendong; Guo, Min; Zhang, Mei; Liu, Jingbo

    2014-11-01

    Bauxite tailings are a major type of solid wastes generated in the flotation process. The waste by-products caused significant environmental impact. To lessen this hazardous effect from poisonous mine tailings, a feasible and cost-effective solution was conceived and implemented. Our approach focused on reutilization of the bauxite tailings by converting it to 4A zeolite for reuse in diverse applications. Three steps were involved in the bauxite conversion: wet-chemistry, alkali fusion, and crystallization to remove impurities and to prepare porous 4A zeolite. It was found that the cubic 4A zeolite was single phase, in high purity, with high crystallinity and well-defined structure. Importantly, the 4A zeolite displayed maximum calcium ion exchange capacity averaged at 296 mg CaCO3/g, comparable to commercially-available zeolite (310 mg CaCO3/g) exchange capacity. Base on the optimal synthesis condition, the reaction yield of zeolite 4A from bauxite tailings achieved to about 38.43%, hence, this study will provide a new paradigm for remediation of bauxite tailings, further mitigating the environmental and health care concerns, particularly in the mainland of PR China. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Graphene oxide membranes with high permeability and selectivity for dehumidification of air

    SciTech Connect

    Shin, Yongsoon; Liu, Wei; Schwenzer, Birgit; Manandhar, Sandeep; Chase-Woods, Dylan; Engelhard, Mark H.; Devanathan, Ram; Fifield, Leonard S.; Bennett, Wendy D.; Ginovska, Bojana; Gotthold, David W.

    2016-09-01

    Hierarchically stacked 2D graphene oxide (GO) membranes are a fascinating and promising new class of materials with the potential for radically improved water vapor/gas separation with excellent selectivity and high permeability. This paper details dehumidification results from flowing gas mixtures through free-standing GO membrane samples prepared by a casting method. The first demonstrated use of free-standing GO membranes for water vapor separation reveals outstanding water vapor permeability and H2O/N2 selectivity. Free-standing GO membranes exhibit extremely high water vapor permeability of 1.82 x 105 Barrer and a water vapor permeance of 1.01 x 10-5 mol/m2sPa, while the nitrogen permeability was below the system’s detection limit, yielding a selectivity >104 in 80% relative humidity (RH) air at 30.8 °C. The results show great potential for a range of energy conversion and environmental applications

  6. High Electron Mobility Transistors (HEMT). Selected Papers

    DTIC Science & Technology

    2010-06-01

    phase shifts experienced by the incident electron aElectronic mail: linzhou@asu.edu. FIG. 1. Cross-sectional high-resolution TEM image recorded in 112...strongly diffracting condition and has a uniform potential through its projected thickness, then the relationship between the holographic phase shift ...of AFRL-RY-WP-TR-2010-1178. 15. SUBJECT TERMS microelectronics, heterostructure, holography , modeling/simulation 16. SECURITY CLASSIFICATION OF

  7. A two-dimensional analysis of mode conversion at a resonance layer with high-magnetic field side reflection

    NASA Astrophysics Data System (ADS)

    Nassiri-Mofakham, Nora; Parvazian, Akbar

    2007-08-01

    Mode converted Bernstein waves potentially allow the implementation of local heating and current drive in spherical torus devices, which are not directly accessible to low-harmonic cyclotron waves. The mode conversion method of Cairns and Lashmore-Davies previously used to study the usual mode conversion in non-planar geometry is extended to include the effect of the high-magnetic-field-side cutoff, and is solved analytically. The analytic solutions to the triplet, cutoff-resonance-cutoff, equations give the reflection and conversion coefficients in terms of parameters defining the local behavior of the dispersion relation. The variation of mode conversion efficiency depends not only on the coupling parameter but also on the phasing effect introduced by the high-field-side cutoff. The change in characteristic phases, which are concerned with the coupling parameter, brings an additional degree of freedom allowing optimization via the position of the high-field cutoff. A discrete spectrum of phases exists for which complete mode conversion of the incident wave for a transit of the resonance region can be achieved. The results we obtain here give the general conditions for efficient Bernstein wave heating in two-dimensional geometry.

  8. Reduced SnO2 Porous Nanowires with a High Density of Grain Boundaries as Catalysts for Efficient Electrochemical CO2 -into-HCOOH Conversion.

    PubMed

    Kumar, Bijandra; Atla, Veerendra; Brian, J Patrick; Kumari, Sudesh; Nguyen, Tu Quang; Sunkara, Mahendra; Spurgeon, Joshua M

    2017-03-20

    Electrochemical conversion of CO2 into energy-dense liquids, such as formic acid, is desirable as a hydrogen carrier and a chemical feedstock. SnOx is one of the few catalysts that reduce CO2 into formic acid with high selectivity but at high overpotential and low current density. We show that an electrochemically reduced SnO2 porous nanowire catalyst (Sn-pNWs) with a high density of grain boundaries (GBs) exhibits an energy conversion efficiency of CO2 -into-HCOOH higher than analogous catalysts. HCOOH formation begins at lower overpotential (350 mV) and reaches a steady Faradaic efficiency of ca. 80 % at only -0.8 V vs. RHE. A comparison with commercial SnO2 nanoparticles confirms that the improved CO2 reduction performance of Sn-pNWs is due to the density of GBs within the porous structure, which introduce new catalytically active sites. Produced with a scalable plasma synthesis technology, the catalysts have potential for application in the CO2 conversion industry.

  9. Feasible conversion of solid waste bauxite tailings into highly crystalline 4A zeolite with valuable application

    SciTech Connect

    Ma, Dongyang; Wang, Zhendong; Guo, Min; Zhang, Mei; Liu, Jingbo

    2014-11-15

    Highlights: • Concept to convert waste to valuable product is carried out in this study. • An industrially feasible and cost-effective approach was developed and optimized. • Highly crystalline and well-defined zeolite was produced under moderate conditions. • The zeolite derived from the bauxite tailings displayed high ion exchange capacity. • Bauxite tailings have potential application in heavy metal ions adsorbent. - Abstract: Bauxite tailings are a major type of solid wastes generated in the flotation process. The waste by-products caused significant environmental impact. To lessen this hazardous effect from poisonous mine tailings, a feasible and cost-effective solution was conceived and implemented. Our approach focused on reutilization of the bauxite tailings by converting it to 4A zeolite for reuse in diverse applications. Three steps were involved in the bauxite conversion: wet-chemistry, alkali fusion, and crystallization to remove impurities and to prepare porous 4A zeolite. It was found that the cubic 4A zeolite was single phase, in high purity, with high crystallinity and well-defined structure. Importantly, the 4A zeolite displayed maximum calcium ion exchange capacity averaged at 296 mg CaCO{sub 3}/g, comparable to commercially-available zeolite (310 mg CaCO{sub 3}/g) exchange capacity. Base on the optimal synthesis condition, the reaction yield of zeolite 4A from bauxite tailings achieved to about 38.43%, hence, this study will provide a new paradigm for remediation of bauxite tailings, further mitigating the environmental and health care concerns, particularly in the mainland of PR China.

  10. Highly-efficient enzymatic conversion of crude algal oils into biodiesel.

    PubMed

    Wang, Yao; Liu, Jin; Gerken, Henri; Zhang, Chengwu; Hu, Qiang; Li, Yantao

    2014-11-01

    Energy-intensive chemical conversion of crude algal oils into biodiesel is a major barrier for cost-effective algal biofuel production. To overcome this problem, we developed an enzyme-based platform for conversion of crude algal oils into fatty acid methyl esters. Crude algal oils were extracted from the oleaginous microalga Nannochloropsis oceanica IMET1 and converted by an immobilized lipase from Candida antarctica. The effects of different acyl acceptors, t-butanol as a co-solvent, oil to t-butanol ratio, oil to methanol ratio, temperature and reaction time on biodiesel conversion efficiency were studied. The conversion efficiency reached 99.1% when the conversion conditions were optimized, i.e., an oil to t-butanol weight ratio of 1:1, an oil to methanol molar ratio of 1:12, and a reaction time of 4h at 25°C. The enzymatic conversion process developed in this study may hold a promise for low energy consumption, low wastewater-discharge biochemical conversion of algal feedstocks into biofuels.

  11. Absorbed-dose beam quality conversion factors for cylindrical chambers in high energy photon beams.

    PubMed

    Seuntjens, J P; Ross, C K; Shortt, K R; Rogers, D W

    2000-12-01

    Recent working groups of the AAPM [Almond et al., Med. Phys. 26, 1847 (1999)] and the IAEA (Andreo et al., Draft V.7 of "An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water," IAEA, 2000) have described guidelines to base reference dosimetry of high energy photon beams on absorbed dose to water standards. In these protocols use is made of the absorbed-dose beam quality conversion factor, kQ which scales an absorbed-dose calibration factor at the reference quality 60Co to a quality Q, and which is calculated based on state-of-the-art ion chamber theory and data. In this paper we present the measurement and analysis of beam quality conversion factors kQ for cylindrical chambers in high-energy photon beams. At least three chambers of six different types were calibrated against the Canadian primary standard for absorbed dose based on a sealed water calorimeter at 60Co [TPR10(20)=0.572, %dd(10)x=58.4], 10 MV [TPR10(20)=0.682, %dd(10)x=69.6), 20 MV (TPR10(20)=0.758, %dd(10)x= 80.5] and 30 MV [TPR10(20) = 0.794, %dd(10)x= 88.4]. The uncertainty on the calorimetric determination of kQ for a single chamber is typically 0.36% and the overall 1sigma uncertainty on a set of chambers of the same type is typically 0.45%. The maximum deviation between a measured kQ and the TG-51 protocol value is 0.8%. The overall rms deviation between measurement and the TG-51 values, based on 20 chambers at the three energies, is 0.41%. When the effect of a 1 mm PMMA waterproofing sleeve is taken into account in the calculations, the maximum deviation is 1.1% and the overall rms deviation between measurement and calculation 0.48%. When the beam is specified using TPR10(20), and measurements are compared with kQ values calculated using the version of TG-21 with corrected formalism and data, differences are up to 1.6% when no sleeve corrections are taken into account. For the NE2571 and the NE2611A chamber types, for which the most literature data are

  12. Feasibility survey on international cooperation for high efficiency energy conversion technology in fiscal 1993

    NASA Astrophysics Data System (ADS)

    1994-03-01

    Following cooperative researches on fuel cell jointly conducted by NEDO and EGAT (Electricity Generating Authority of Thailand), the survey on international cooperation relating to high efficiency energy conversion technology was carried out for the ASEAN countries. The paper summed up the results of the survey. The study of the international cooperation is made for the following three items: a program for periodical exchange of information with EGAT, a project for cooperative research on phosphoric acid fuel cell in Indonesia, and a project for cooperative research with EGAT on electric power storage by advanced battery. In Malaysia, which is small in scale of state, part of the Ministry of Energy, Telecommunication and Posts is only in charge of the energy issue. Therefore, the situation is that they cannot answer well to many items of research/development cooperation brought in from Japan. The item of medium- and long-term developmental research in the Philippines is about the problems which are seen subsequently in the Manila metropolitan area where the problem of outage is being settled. Accordingly, it is essential to promote the cooperative research, well confirming policies and systems of the Ministry of Energy and the national electricity corporation.

  13. Tips for selecting highly efficient cyclones

    SciTech Connect

    Amrein, D.L.

    1995-05-01

    Cyclone dust collectors have been used--and misused--all over the world for more than 100 years. One reason for the misuse is a common perception among users that all cyclones are created equal--that is, as long as a cyclone resembles a cylinder with an attached cone, it will do its job. However, to maximize separation efficiency in a specific application requires a precise cyclone design, engineered to exact fit many possible variables. A well-designed cyclone, for instance, can achieve efficiencies as high s 99.9+% when operated properly within the envelope of its specifications. Nonetheless, cyclones are often used only as first-stage filters for performing crude separations, with final collections being carried out by more-costly baghouses and scrubbers. Compared with baghouses and scrubbers, cyclones have two important considerations in their favor. One, they are almost invariably safer--in terms of the potential for generating fires and explosions--than fabric filters. Second, cyclones have lower maintenance costs since there are no filter media to replace. The paper discusses the operation, design, and troubleshooting of cyclones.

  14. High-anthocyanin strawberries through cultivar selection.

    PubMed

    Fredericks, Charissa H; Fanning, Kent J; Gidley, Michael J; Netzel, Gabriele; Zabaras, Dimitrios; Herrington, Mark; Netzel, Michael

    2013-03-15

    Diets high in fruit and vegetables are known to have significant health benefits. This is in part due to the presence of phytochemicals, which possess potential protective health benefits. This study focuses on the ability of strawberries to be bred for higher anthocyanin content. This is a major contributor to the characteristic colour and nutritional value of ripe strawberries, together with phenolic acids, ascorbic acid and total antioxidant capacity. Anthocyanins in five commercial strawberry cultivars and three breeding lines were assessed. This led to the discovery of one breeding line (BL 2006-221) as an exceptional source of anthocyanins (~1 g kg(-1) fresh weight), with approximately double the levels of current commercial cultivars. Temperature was shown to influence anthocyanin extraction, with 40 °C being the best extraction temperature using the accelerated solvent extraction (ASE) method. Hue angle and anthocyanin concentration showed a good correlation (r(2) = 0.69). The new breeding line BL 2006-221 has the potential to be used in the development of phytochemically rich strawberry cultivars. Using hue angle as a screening tool for total anthocyanin concentration and extraction of anthocyanins from strawberries by ASE at 40 °C would support such cultivar development. © 2012 Commonwealth of Australia.

  15. Low-Enriched Uranium Fuel Conversion Activities for the High Flux Isotope Reactor, Annual Report for FY 2011

    SciTech Connect

    Renfro, David G; Cook, David Howard; Freels, James D; Griffin, Frederick P; Ilas, Germina; Sease, John D; Chandler, David

    2012-03-01

    This report describes progress made during FY11 in ORNL activities to support converting the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Conversion from HEU to LEU will require a change in fuel form from uranium oxide to a uranium-molybdenum (UMo) alloy. With both radial and axial contouring of the fuel foil and an increase in reactor power to 100 MW, calculations indicate that the HFIR can be operated with LEU fuel with no degradation in performance to users from the current levels achieved with HEU fuel. Studies are continuing to demonstrate that the fuel thermal safety margins can be preserved following conversion. Studies are also continuing to update other aspects of the reactor steady state operation and accident response for the effects of fuel conversion. Technical input has been provided to Oregon State University in support of their hydraulic testing program. The HFIR conversion schedule was revised and provided to the GTRI program. In addition to HFIR conversion activities, technical support was provided directly to the Fuel Fabrication Capability program manager.

  16. Plastic Work to Heat Conversion During High-Strain Rate Deformation of Mg and Mg Alloy

    NASA Astrophysics Data System (ADS)

    Ghosh, Dipankar; Kingstedt, Owen T.; Ravichandran, Guruswami

    2017-01-01

    Magnesium and magnesium alloy were investigated for plastic work to heat conversion ( β). Thermomechanical response was measured employing the shear-compression specimen geometry, a split-Hopkinson pressure bar, and an infra-red detector. β of both materials measured to be less than the common assumption of 0.9; however, heat conversion was observed to be greater for magnesium alloy. Thus, results suggest that alloying and grain size refinement not only improved yield strength but also affected the thermomechanical response.

  17. Ultrafast internal conversion dynamics of highly excited pyrrole studied with VUV/UV pump probe spectroscopy

    NASA Astrophysics Data System (ADS)

    Horton, Spencer L.; Liu, Yusong; Chakraborty, Pratip; Matsika, Spiridoula; Weinacht, Thomas

    2017-02-01

    We study the relaxation dynamics of pyrrole after excitation with an 8 eV pump pulse to a state just 0.2 eV below the ionization potential using vacuum ultraviolet/ultraviolet pump probe spectroscopy. Our measurements in conjunction with electronic structure calculations indicate that pyrrole undergoes rapid internal conversion to the ground state in less than 300 fs. We find that internal conversion to the ground state dominates over dissociation.

  18. Feasibility analyses for HEU to LEU fuel conversion of the LAUE Langivin Institute (ILL) High Flux Reactor (RHF).

    SciTech Connect

    Stevens, J.; Tentner. A.; Bergeron, A.; Nuclear Engineering Division

    2010-08-19

    The High Flux Reactor (RHF) of the Laue Langevin Institute (ILL) based in Grenoble, France is a research reactor designed primarily for neutron beam experiments for fundamental science. It delivers one of the most intense neutron fluxes worldwide, with an unperturbed thermal neutron flux of 1.5 x 10{sup 15} n/cm{sup 2}/s in its reflector. The reactor has been conceived to operate at a nuclear power of 57 MW but currently operates at 52 MW. The reactor currently uses a Highly Enriched Uranium (HEU) fuel. In the framework of its non-proliferation policies, the international community presently aims to minimize the amount of nuclear material available that could be used for nuclear weapons. In this geopolitical context, most worldwide research and test reactors have already started a program of conversion to the use of Low Enriched Uranium (LEU) fuel. A new type of LEU fuel based on a mixture of uranium and molybdenum (UMo) is expected to allow the conversion of compact high performance reactors like the RHF. This report presents the results of reactor design, performance and steady state safety analyses for conversion of the RHF from the use of HEU fuel to the use of UMo LEU fuel. The objective of this work was to show that is feasible, under a set of manufacturing assumptions, to design a new RHF fuel element that could safely replace the HEU element currently used. The new proposed design has been developed to maximize performance, minimize changes and preserve strong safety margins. Neutronics and thermal-hydraulics models of the RHF have been developed and qualified by benchmark against experiments and/or against other codes and models. The models developed were then used to evaluate the RHF performance if LEU UMo were to replace the current HEU fuel 'meat' without any geometric change to the fuel plates. Results of these direct replacement analyses have shown a significant degradation of the RHF performance, in terms of both neutron flux and cycle length

  19. Independent stratum formation on the avian sex chromosomes reveals inter-chromosomal gene conversion and predominance of purifying selection on the W chromosome.

    PubMed

    Wright, Alison E; Harrison, Peter W; Montgomery, Stephen H; Pointer, Marie A; Mank, Judith E

    2014-11-01

    We used a comparative approach spanning three species and 90 million years to study the evolutionary history of the avian sex chromosomes. Using whole transcriptomes, we assembled the largest cross-species dataset of W-linked coding content to date. Our results show that recombination suppression in large portions of the avian sex chromosomes has evolved independently, and that long-term sex chromosome divergence is consistent with repeated and independent inversions spreading progressively to restrict recombination. In contrast, over short-term periods we observe heterogeneous and locus-specific divergence. We also uncover four instances of gene conversion between both highly diverged and recently evolved gametologs, suggesting a complex mosaic of recombination suppression across the sex chromosomes. Lastly, evidence from 16 gametologs reveal that the W chromosome is evolving with a significant contribution of purifying selection, consistent with previous findings that W-linked genes play an important role in encoding sex-specific fitness. © 2014 The Authors. Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  20. Optimal thermionic energy conversion with established electrodes for high-temperature topping and process heating

    SciTech Connect

    Morris, J.F.

    1980-07-01

    Advantages of thermionic energy conversion (TEC) have been counted and are recounted with emphasis on high-temperature service in coal-combustion products. Efficient, economical, nonpolluting utilization of coal here and now is a critically important national goal. And TEC can augment this capability not only by the often proposed topping of steam power plants but also by higher-temperature topping and process heating. For these applications, applied-research-and-technology (ART) work reveals that optimal TEC with approx. 1000-to approx. 1100 K collectors is possible using well-established tungsten electrodes. Such TEC with 1800 K emitters could approach 26.6% efficiency at 27.4 W/cm/sup 2/ with approx. 1000 K collectors and 21.7% at 22.6 W/cm/sup 2/ with approx. 1100 K collectors. These performances require 1.5- and 1.7-eV collector work functions (not the 1-eV ultimate) with nearly negligible interelectrode losses. Such collectors correspond to tungsten electrode systems in approx. 0.9-to approx. 6-torr cesium pressures with 1600-to-1900 K emitters. Because higher heat-rejection temperatures for TEC allow greater collector work functions, interelectrode-loss reduction becomes an increasingly important target for applications aimed at elevated temperatures. Studies of intragap modifications and new electrodes that will allow better electron emission and collection with lower cesium pressures are among the TEC-ART approaches to reduced interelectrode losses. These solutions will provide very effective TEC to serve directly in coal-combustion products for high-temperature topping and process heating. In turn this will help to use coal-and to use it well.

  1. Department of Defense Curricula: Information Concerning Conversion for Civilian Use.

    ERIC Educational Resources Information Center

    Forgione, Pascal D., Jr.; Orth, Mollie N.

    Designed to assist in the selection of national priorities for the conversion of military curricula to civilian use, a study selected curricula pertinent to occupations with high growth potential and evaluated them against criteria important for curriculum conversion decisions. Procedures consisted of identification of priority occupational areas…

  2. Korean Born, Korean-American High School Students' Entry into Understanding Race and Racism through Social Interactions and Conversations

    ERIC Educational Resources Information Center

    Palmer, John D.; Jang, Eun-Young

    2005-01-01

    This paper explores how a group of Korean born, Korean-American high school students came to understand race and racism in the US through social interactions and conversations, with particular attention paid to the locality of time, space and people engaged. Therefore, we explore not only how race and racism are socially constructed in the lives…

  3. Ranking Hearing Aid Input-Output Functions for Understanding Low-, Conversational-, and High-Level Speech in Multitalker Babble

    ERIC Educational Resources Information Center

    Chung, King; Killion, Mead C.; Christensen, Laurel A.

    2007-01-01

    Purpose: To determine the rankings of 6 input-output functions for understanding low-level, conversational, and high-level speech in multitalker babble without manipulating volume control for listeners with normal hearing, flat sensorineural hearing loss, and mildly sloping sensorineural hearing loss. Method: Peak clipping, compression limiting,…

  4. Ranking Hearing Aid Input-Output Functions for Understanding Low-, Conversational-, and High-Level Speech in Multitalker Babble

    ERIC Educational Resources Information Center

    Chung, King; Killion, Mead C.; Christensen, Laurel A.

    2007-01-01

    Purpose: To determine the rankings of 6 input-output functions for understanding low-level, conversational, and high-level speech in multitalker babble without manipulating volume control for listeners with normal hearing, flat sensorineural hearing loss, and mildly sloping sensorineural hearing loss. Method: Peak clipping, compression limiting,…

  5. All-fiber fused directional coupler for highly efficient spatial mode conversion.

    PubMed

    Ismaeel, Rand; Lee, Timothy; Oduro, Bernard; Jung, Yongmin; Brambilla, Gilberto

    2014-05-19

    We model and demonstrate a simple mode selective all-fiber coupler capable of exciting specific higher order modes in two- and few-mode fibres with high efficiency and purity. The coupler is based on inter-modally phase-matching the propagation constants in each arm of the asymmetric fused coupler, formed by dissimilar fibres. At a specific coupler diameter, the launched fundamental LP(01) mode is coupled into the higher order mode (LP(11), LP(21), LP(02)) in the other arm, over a broadband wave-length range around 1550 nm. Unlike other techniques, the demonstrated coupler is composed of a multimode fiber that is weakly fused with a phase matched conventional single mode telecom fiber (SMF-28). The beating between the supermodes at the coupler waist produces a periodic power transfer between the two arms, and therefore, by monitoring the beating while tapering, it is possible to obtain optimum selection for the desired mode. High coupling efficiencies in excess of 90% for all the higher order modes were recorded over 100 nm spectral range, while insertion losses remain as low as 0.5 dB. Coupling efficiency can be further enhanced by performing slow tapering at high temperature, in order to precisely control the coupler cross-section geometry.

  6. EDITORIAL: Selected papers from the 11th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2011) Selected papers from the 11th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2011)

    NASA Astrophysics Data System (ADS)

    Cho, Young-Ho

    2012-09-01

    This special section of Journal of Micromechanics and Microengineering features papers selected from the 11th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2011), held at Sejong Hotel in Seoul, Korea during 15-18 November 2011. Since the first PowerMEMS workshop held in Sendai, Japan in 2000, the workshop has developed as the premier forum for reporting research results in micro and nanotechnology for power generation, energy conversion, harvesting and processing applications, including in-depth technical issues on nanostructures and materials for small-scale high-density energy and thermal management. Potential PowerMEMS applications cover not only portable power devices for consumer electronics and remote sensors, but also micro engines, impulsive thrusters and fuel cells for systems ranging from the nanometer to the millimeter scale. The 2011 technical program consists of 1 plenary talk, 4 invited talks and 118 contributed presentations. The 48 oral and 70 poster presentations, selected by 27 Technical Program Committee Members from 131 submitted abstracts, have stimulated lively discussion maximizing the interaction between participants. Among them, this special section includes 9 papers covering micro-scale power generators, energy converters, harvesters, thrusters and thermal coolers. Finally, we are grateful to the members of the International Steering Committee, the Technical Program Committee, and the Local Organizing Committee for their efforts and contributions to PowerMEMS 2011. We also thank the two companies Samsung Electro-Mechanics and LG Elite for technical tour arrangements. Special thanks go to Dr Ian Forbes, the editorial staff of the Journal of Micromechanics and Microengineering, as well as to the staff of IOP Publishing for making this special section possible.

  7. Frequency conversion system

    NASA Technical Reports Server (NTRS)

    Sanders, Steven (Inventor); Lang, Robert J. (Inventor)

    2001-01-01

    Laser diode pumped mid-IR wavelength sources include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

  8. Development of a High Fluence, High Conversion Efficiency X-Ray Silver Metal Foam Source at the NIF

    NASA Astrophysics Data System (ADS)

    May, M. J.; Colvin, J. D.; Kemp, G. E.; Thorn, D.; Widmann, K.; Blue, B. E.,

    2016-10-01

    High x-ray conversion efficiency (XRCE) L-shell Ag sources are being developed for High Energy Density experiments. The targets are nominally 4 mm in diameter, 4 mm tall cylinders of free standing Ag metal foam with densities of 10 - 30 mg/cm3 and made by a new technique of freeze drying an aqueous suspension of Ag nano wires. 192 laser beams from NIF are used to heat the targets with 150 TW of power in a 4 ns square in time pulse depositing 600 kJ into the target. XRCEs from these targets have been measured by using the Dante diode spectrometer to be 7% which is much less than the predictions from simulations. The nano wires at nominal solid density might not be homogenized sufficiently by the laser heating pulse which could limit the XRCE. To increase the XRCE, we plan to use a laser prepulse of 1 kJ to preheat the nano wires in the target before the main laser heating pulse. The results of these experiments will be discussed. This work was performed under the auspices of the US Department of Energy by University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

  9. The roadmap for low price- high performance IR detector based on LWIR to NIR light up-conversion approach

    NASA Astrophysics Data System (ADS)

    Kipper, R.; Arbel, D.; Baskin, E.; Fayer, A.; Epstein, A.; Shuall, N.; Saguy, A.; Veksler, D.; Spektor, B.; Ben-Aharon, D.; Garber, V.

    2009-05-01

    The introduction of an uncooled microbolometer image sensor about a decade ago enabled cost reduction of IR cameras. As a result, the available markets grew both in military and civilian applications. Since then, the price of microbolometer was gradually reduced due to introduction of devices with smaller pixel, maturity of the technology and quantity growth. However, the requirement for a vacuum package still limits the price of microbolometer based cameras to several thousands of dollars. Sirica's novel wavelength conversion technology aims at breaking this paradigm by being uncooled and vacuumless, lowering IR camera prices by an order of magnitude, opening the way to new mass markets. Sirica's proprietary IR-to-Visible/NIR conversion layer allows for low-cost high performance LWIR detector with no requirement for cooling and vacuum packaging. In the last years, the development efforts focused on development of the conversion media. Recently, a parallel effort for the integration of the conversion layer together with other detector components has started. Packaging of detector components, such as conversion layer, pumping light source, dichroic filter, and their coupling with silicon CMOS image sensor have great importance from a price-performance point of view. According to the company's business-development roadmap, the detector prototype should be available during the first quarter of 2010.

  10. The surprising negative correlation of gene length and optimal codon use--disentangling translational selection from GC-biased gene conversion in yeast.

    PubMed

    Stoletzki, Nina

    2011-04-11

    Surprisingly, in several multi-cellular eukaryotes optimal codon use correlates negatively with gene length. This contrasts with the expectation under selection for translational accuracy. While suggested explanations focus on variation in strength and efficiency of translational selection, it has rarely been noticed that the negative correlation is reported only in organisms whose optimal codons are biased towards codons that end with G or C (-GC). This raises the question whether forces that affect base composition--such as GC-biased gene conversion--contribute to the negative correlation between optimal codon use and gene length. Yeast is a good organism to study this as equal numbers of optimal codons end in -GC and -AT and one may hence compare frequencies of optimal GC- with optimal AT-ending codons to disentangle the forces. Results of this study demonstrate in yeast frequencies of GC-ending (optimal AND non-optimal) codons decrease with gene length and increase with recombination. A decrease of GC-ending codons along genes contributes to the negative correlation with gene length. Correlations with recombination and gene expression differentiate between GC-ending and optimal codons, and also substitution patterns support effects of GC-biased gene conversion. While the general effect of GC-biased gene conversion is well known, the negative correlation of optimal codon use with gene length has not been considered in this context before. Initiation of gene conversion events in promoter regions and the presence of a gene conversion gradient most likely explain the observed decrease of GC-ending codons with gene length and gene position.

  11. Conversion of basal plane dislocations to threading edge dislocations in 4H-SiC epilayers by high temperature annealing

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; Tsuchida, Hidekazu

    2012-06-01

    Conversion of basal plane dislocations (BPDs) to threading edge dislocations (TEDs) is found in 4H-SiC epilayers after being annealed simply at high temperatures. Grazing incidence reflection synchrotron x-ray topography for the dislocations in the epilayers before and after annealing confirmed that some of the BPDs in the epilayers had converted to TEDs from the epilayer surface by the annealing. Observations on the dislocation behavior during annealing are explained in detail, and the mechanism of BPD conversion is discussed. It is argued that the conversion proceeds through the cross slip of constricted BPD segments towards the surface on the prismatic plane driven by the image force as well as TED glide driven by the line tension. Certain kinetic processes during annealing may facilitate the formation of constriction.

  12. Study of solid-conversion gaseous detector based on GEM for high energy X-ray industrial CT.

    PubMed

    Zhou, Rifeng; Zhou, Yaling

    2014-01-01

    The general gaseous ionization detectors are not suitable for high energy X-ray industrial computed tomography (HEICT) because of their inherent limitations, especially low detective efficiency and large volume. The goal of this study was to investigate a new type of gaseous detector to solve these problems. The novel detector was made by a metal foil as X-ray convertor to improve the conversion efficiency, and the Gas Electron Multiplier (hereinafter "GEM") was used as electron amplifier to lessen its volume. The detective mechanism and signal formation of the detector was discussed in detail. The conversion efficiency was calculated by using EGSnrc Monte Carlo code, and the transport course of photon and secondary electron avalanche in the detector was simulated with the Maxwell and Garfield codes. The result indicated that this detector has higher conversion efficiency as well as less volume. Theoretically this kind of detector could be a perfect candidate for replacing the conventional detector in HEICT.

  13. International Atomic Energy Agency support of research reactor highly enriched uranium to low enriched uranium fuel conversion projects

    SciTech Connect

    Bradley, E.; Adelfang, P.; Goldman, I.N.

    2008-07-15

    The IAEA has been involved for more than twenty years in supporting international nuclear non- proliferation efforts associated with reducing the amount of highly enriched uranium (HEU) in international commerce. IAEA projects and activities have directly supported the Reduced Enrichment for Research and Test Reactors (RERTR) programme, as well as directly assisted efforts to convert research reactors from HEU to LEU fuel. HEU to LEU fuel conversion projects differ significantly depending on several factors including the design of the reactor and fuel, technical needs of the member state, local nuclear infrastructure, and available resources. To support such diverse endeavours, the IAEA tailors each project to address the relevant constraints. This paper presents the different approaches taken by the IAEA to address the diverse challenges involved in research reactor HEU to LEU fuel conversion projects. Examples of conversion related projects in different Member States are fully detailed. (author)

  14. Nanocrystal-based light-emitting diodes utilizing high-efficiency nonradiative energy transfer for color conversion.

    PubMed

    Achermann, Marc; Petruska, Melissa A; Koleske, Daniel D; Crawford, Mary H; Klimov, Victor I

    2006-07-01

    We report a practical implementation of high-efficiency color conversion in an electrically pumped light-emitting diode (LED) using nonradiative energy transfer. On the basis of a new LED design that offers both strong energy-transfer coupling and efficient carrier injection, we show that a hybrid structure comprising a single monolayer of CdSe nanocrystals assembled on top of an InGaN/GaN quantum well provides nearly 10% color conversion efficiency. This value is significantly higher than that for a traditional absorption-re-emission color-conversion scheme in a similar device structure. Furthermore, these hybrid devices can also provide improved efficiencies, compared not only to phosphor-based structures but also to stand-alone LEDs.

  15. Solid Electrolyte Lithium Phosphous Oxynitride as a Protective Nanocladding Layer for 3D High-Capacity Conversion Electrodes.

    PubMed

    Lin, Chuan-Fu; Noked, Malachi; Kozen, Alexander C; Liu, Chanyuan; Zhao, Oliver; Gregorczyk, Keith; Hu, Liangbing; Lee, Sang Bok; Rubloff, Gary W

    2016-02-23

    Materials that undergo conversion reactions to form different materials upon lithiation typically offer high specific capacity for energy storage applications such as Li ion batteries. However, since the reaction products often involve complex mixtures of electrically insulating and conducting particles and significant changes in volume and phase, the reversibility of conversion reactions is poor, preventing their use in rechargeable (secondary) batteries. In this paper, we fabricate and protect 3D conversion electrodes by first coating multiwalled carbon nanotubes (MWCNT) with a model conversion material, RuO2, and subsequently protecting them with conformal thin-film lithium phosphous oxynitride (LiPON), a well-known solid-state electrolyte. Atomic layer deposition is used to deposit the RuO2 and the LiPON, thus forming core double-shell MWCNT@RuO2@LiPON electrodes as a model system. We find that the LiPON protection layer enhances cyclability of the conversion electrode, which we attribute to two factors. (1) The LiPON layer provides high Li ion conductivity at the interface between the electrolyte and the electrode. (2) By constraining the electrode materials mechanically, the LiPON protection layer ensures electronic connectivity and thus conductivity during lithiation/delithiation cycles. These two mechanisms are striking in their ability to preserve capacity despite the profound changes in structure and composition intrinsic to conversion electrode materials. This LiPON-protected structure exhibits superior cycling stability and reversibility as well as decreased overpotentials compared to the unprotected core-shell structure. Furthermore, even at very low lithiation potential (0.05 V), the LiPON-protected electrode largely reduces the formation of a solid electrolyte interphase.

  16. Characterization of selected Ohio coals to predict their conversion behavior relative to 104 North American Coals. [Factors correlating with liquefaction behavior

    SciTech Connect

    Whitacre, T. P.; Hunt, T. J.; Kneller, W. A.

    1982-02-01

    Twenty-six coal samples from Ohio were collected as washed and seam samples, and lithobodies within the seams. Characterization of these samples included determination of % maceral, % anti R/sub max/, LTA, chlorine content and proximate/ultimate and qualitative mineral analyses. These data were compared to data from a similar project by Yarzab, R.F., et al., 1980 completed at Pennsylvania State University using tetralin as the hydrogen donor solvent. The characteristics of these coals were correlated with liquefaction conversion and other data accrued on 104 North American coals by statistical analyses. Utilizing percent carbon, sulfur, volatile matter, reflectance, vitrinite and total reactive macerals, Q-mode cluster analysis demonstrated that Ohio coals are more similar to the coals of the Interior province than to those of the Appalachian province. Linear multiple regression analysis for the 104 North American coals provided a prediction equation for conversion (R = .96). The predicted conversion values for the samples range from 58.8 to 79.6%, with the Lower Kittanning (No. 5) and the Middle Kittanning (No. 6) coal seams showing the highest predicted percent conversion (respectively, 73.4 and 72.2%). The moderately low FSI values for the No. 5 and No. 6 coals (respectively, 2.5 and 3) and their moderately high alkaline earth content (respectively, 0.69 and 0.74%) suggest that these coals possess the best overall properties for conversion. Stepwise regression has indicated that the most important coal characteristics affecting conversion are, in decreasing order of importance: % volatile matter, % vitrinite and % total sulfur. Conversion processes can be expected to produce higher yields with Ohio coals due to the presence of such mineral catalysts as pyrite and kaolinite. It is believed that the presence of these disposable catalysts increases the marketability of Ohio coals.

  17. A Model for Investigating Predictive Validity at Highly Selective Institutions.

    ERIC Educational Resources Information Center

    Gross, Alan L.; And Others

    A statistical model for investigating predictive validity at highly selective institutions is described. When the selection ratio is small, one must typically deal with a data set containing relatively large amounts of missing data on both criterion and predictor variables. Standard statistical approaches are based on the strong assumption that…

  18. Stability of high temperature chemical vapor deposited silicon based structures on metals for solar conversion.

    PubMed

    Gelard, Isabelle; Chichignoud, Guy; Blanquet, Elisabeth; Xuan, Hoan Nguyen; Cruz, Ruben; Jimenez, Carmen; Sarigiannidou, Eirini; Zaidat, Kader

    2011-09-01

    Highly crystallized silicon layers were grown on metal sheets at high temperature (950 degrees C) by thermal CVD from silane. An intermediate buffer layer was mandatory to prevent interdiffusion and silicide formation but also to compensate lattice parameters and thermal expansion coefficients mismatches between metal and silicon and ideally transfer some crystalline properties (grain size, texture) from the substrate to the silicon layer. After a thermodynamic study, aluminum nitride or titanium nitride diffusion barrier layers were selected and processed by CVD. The structure and the interfaces stabilities of these silicon/nitride/metal stacks were studied by field effect gun scanning and transmission electron microscopy, X-ray diffraction, Raman and energy dispersive X-ray spectroscopy. As a result, TiN deposited by CVD appears to be an efficient material as a buffer layer between steel and silicon.

  19. Thermal conversion of core-shell metal-organic frameworks: a new method for selectively functionalized nanoporous hybrid carbon.

    PubMed

    Tang, Jing; Salunkhe, Rahul R; Liu, Jian; Torad, Nagy L; Imura, Masataka; Furukawa, Shuhei; Yamauchi, Yusuke

    2015-02-04

    Core-shell structured ZIF-8@ZIF-67 crystals are well-designed and prepared through a seed-mediated growth method. After thermal treatment of ZIF-8@ZIF-67 crystals, we obtain selectively functionalized nanoporous hybrid carbon materials consisting of nitrogen-doped carbon (NC) as the cores and highly graphitic carbon (GC) as the shells. This is the first example of the integration of NC and GC in one particle at the nanometer level. Electrochemical data strongly demonstrate that this nanoporous hybrid carbon material integrates the advantageous properties of the individual NC and GC, exhibiting a distinguished specific capacitance (270 F·g(-1)) calculated from the galvanostatic charge-discharge curves at a current density of 2 A·g(-1). Our study not only bridges diverse carbon-based materials with infinite metal-organic frameworks but also opens a new avenue for artificially designed nanoarchitectures with target functionalities.

  20. Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates.

    SciTech Connect

    Lyons, J.E.

    1992-07-01

    The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

  1. Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates

    SciTech Connect

    Lyons, J.E.

    1992-01-01

    The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

  2. High efficiency light source using solid-state emitter and down-conversion material

    DOEpatents

    Narendran, Nadarajah; Gu, Yimin; Freyssinier, Jean Paul

    2010-10-26

    A light emitting apparatus includes a source of light for emitting light; a down conversion material receiving the emitted light, and converting the emitted light into transmitted light and backward transmitted light; and an optic device configured to receive the backward transmitted light and transfer the backward transmitted light outside of the optic device. The source of light is a semiconductor light emitting diode, a laser diode (LD), or a resonant cavity light emitting diode (RCLED). The down conversion material includes one of phosphor or other material for absorbing light in one spectral region and emitting light in another spectral region. The optic device, or lens, includes light transmissive material.

  3. Selective high affinity polydentate ligands and methods of making such

    DOEpatents

    DeNardo, Sally; DeNardo, Gerald; Balhorn, Rodney

    2010-02-16

    This invention provides novel polydentate selective high affinity ligands (SHALs) that can be used in a variety of applications in a manner analogous to the use of antibodies. SHALs typically comprise a multiplicity of ligands that each bind different region son the target molecule. The ligands are joined directly or through a linker thereby forming a polydentate moiety that typically binds the target molecule with high selectivity and avidity.

  4. Development of High Yield Feedstocks and Biomass Conversion Technology for Renewable Energy

    SciTech Connect

    Hashimoto, Andrew G.; Crow, Susan; DeBeryshe, Barbara; Ha, Richard; Jakeway, Lee; Khanal, Samir; Nakahata, Mae; Ogoshi, Richard; Shimizu, Erik; Stern, Ivette; Turano, Brian; Turn, Scott; Yanagida, John

    2015-04-09

    This project had two main goals. The first goal was to evaluate several high yielding tropical perennial grasses as feedstock for biofuel production, and to characterize the feedstock for compatible biofuel production systems. The second goal was to assess the integration of renewable energy systems for Hawaii. The project focused on high-yield grasses (napiergrass, energycane, sweet sorghum, and sugarcane). Field plots were established to evaluate the effects of elevation (30, 300 and 900 meters above sea level) and irrigation (50%, 75% and 100% of sugarcane plantation practice) on energy crop yields and input. The test plots were extensive monitored including: hydrologic studies to measure crop water use and losses through seepage and evapotranspiration; changes in soil carbon stock; greenhouse gas flux (CO2, CH4, and N2O) from the soil surface; and root morphology, biomass, and turnover. Results showed significant effects of environment on crop yields. In general, crop yields decrease as the elevation increased, being more pronounced for sweet sorghum and energycane than napiergrass. Also energy crop yields were higher with increased irrigation levels, being most pronounced with energycane and less so with sweet sorghum. Daylight length greatly affected sweet sorghum growth and yields. One of the energy crops (napiergrass) was harvested at different ages (2, 4, 6, and 8 months) to assess the changes in feedstock characteristics with age and potential to generate co-products. Although there was greater potential for co-products from younger feedstock, the increased production was not sufficient to offset the additional cost of harvesting multiple times per year. The feedstocks were also characterized to assess their compatibility with biochemical and thermochemical conversion processes. The project objectives are being continued through additional support from the Office of Naval Research, and the Biomass Research and Development

  5. Direct X-B mode conversion for high-β national spherical torus experiment in nonlinear regime

    SciTech Connect

    Ali Asgarian, M. E-mail: maa@msu.edu; Parvazian, A.; Abbasi, M.; Verboncoeur, J. P.

    2014-09-15

    Electron Bernstein wave (EBW) can be effective for heating and driving currents in spherical tokamak plasmas. Power can be coupled to EBW via mode conversion of the extraordinary (X) mode wave. The most common and successful approach to study the conditions for optimized mode conversion to EBW was evaluated analytically and numerically using a cold plasma model and an approximate kinetic model. The major drawback in using radio frequency waves was the lack of continuous wave sources at very high frequencies (above the electron plasma frequency), which has been addressed. A future milestone is to approach high power regime, where the nonlinear effects become significant, exceeding the limits of validity for present linear theory. Therefore, one appropriate tool would be particle in cell (PIC) simulation. The PIC method retains most of the nonlinear physics without approximations. In this work, we study the direct X-B mode conversion process stages using PIC method for incident wave frequency f{sub 0} = 15 GHz, and maximum amplitude E{sub 0} = 10{sup 5 }V/m in the national spherical torus experiment (NSTX). The modelling shows a considerable reduction in X-B mode conversion efficiency, C{sub modelling} = 0.43, due to the presence of nonlinearities. Comparison of system properties to the linear state reveals predominant nonlinear effects; EBW wavelength and group velocity in comparison with linear regime exhibit an increment around ∼36% and 17%, respectively.

  6. Hydrogen-Permeable Tubular Membrane Reactor: Promoting Conversion and Product Selectivity for Non-Oxidative Activation of Methane over an Fe©SiO2 Catalyst.

    PubMed

    Sakbodin, Mann; Wu, Yiqing; Oh, Su Cheun; Wachsman, Eric D; Liu, Dongxia

    2016-12-23

    Non-oxidative methane conversion over Fe©SiO2 catalyst was studied for the first time in a hydrogen (H2 ) permeable tubular membrane reactor. The membrane reactor is composed of a mixed ionic-electronic SrCe0.7 Zr0.2 Eu0.1 O3-δ thin film (≈20 μm) supported on the outer surface of a one-end capped porous SrCe0.8 Zr0.2 O3-δ tube. Significant improvement in CH4 conversion was achieved upon H2 removal from the membrane reactor compared to that in a fixed-bed reactor. The Fe©SiO2 catalyst in the H2 permeable membrane reactor demonstrated a stable ≈30 % C2+ single-pass yield, with up to 30 % CH4 conversion and 99 % selectivity to C2 (ethylene and acetylene) and aromatic (benzene and naphthalene) products, at the tested conditions. The selectivity towards C2 or aromatics was manipulated purposely by adding H2 into or removing H2 from the membrane reactor feed and permeate gas streams. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Carbon nanotube nanoweb-bioelectrode for highly selective dopamine sensing.

    PubMed

    Zhao, Jie; Zhang, Weimin; Sherrell, Peter; Razal, Joselito M; Huang, Xu-Feng; Minett, Andrew I; Chen, Jun

    2012-01-01

    A highly sensitive and selective dopamine sensor was fabricated with the unique 3D carbon nanotube nanoweb (CNT-N) electrode. The as-synthesised CNT-N was modified by oxygen plasma to graft functional groups in order to increase selective electroactive sites at the CNT sidewalls. This electrode was characterized physically and electrochemically using HRSEM, Raman, FT-IR, and cyclic voltammetry (CV). Our investigations indicated that the O(2)-plasma treated CNT-N electrode could serve as a highly sensitive biosensor for the selective sensing of dopamine (DA, 1 μM to 20 μM) in the presence of ascorbic acid (AA, 1000 μM).

  8. Highly enhanced energy conversion from the streaming current by polymer addition.

    PubMed

    Nguyen, Trieu; Xie, Yanbo; de Vreede, Lennart J; van den Berg, Albert; Eijkel, Jan C T

    2013-08-21

    In this contribution, we present for the first time the experimental results of energy conversion from the streaming current when a polymer is added to the working solution. We added polyacrylic acid (PAA) in concentrations of 200 ppm to 4000 ppm to a KCl solution. By introducing PAA, the input power, which is the product of volumetric flow rate and the applied pressure, reduced rapidly as compared to the case of using only a normal viscous electrolyte KCl solution. The output power at the same time remained largely constant, whereby an increase of the streaming current and a decrease of the streaming potential simultaneously occurred. These combined factors led to the massive increase of the energy conversion efficiency. Particularly, the results showed that when PAA was in a 0.01 mM KCl solution, the energy conversion efficiency of the system was enhanced by a factor of 447 (±2%), as compared to the case of the solution containing only 0.01 mM KCl. An enhancement factor of 249 (±4%) was also observed when PAA was added to the higher ionic strength background solution, 1 mM KCl. This finding can have practical use in microchannel-array energy conversion systems. When, instead of the negatively charged PAA, a non-ionic polymer polyethylene oxide (PEO) was added to the solution, no efficiency increase was observed, probably due to polymer wall adsorption.

  9. High conversion efficiency pumped-cavity second harmonic generation of a diode laser

    SciTech Connect

    Keicher, D.M.

    1994-01-01

    To investigate the feasibility of producing a compact, efficient blue laser source, pumped-cavity second harmonic generation of diode lasers was explored. It is desirable to have such lasers to increase optical disk storage density, for color displays and for under-the-sea green-blue optical signal transmission. Based on assumed cavity losses, a cavity was designed and numerical analysis predicted an overall conversion efficiency to the second harmonic wavelength of 76% from a 75 mW diode laser. The diode laser used in these experiments had a single longitudinal and a single transverse mode output at 860 nm. The best conversion efficiency obtained (26%) was less than optimum due to the 2.5% single-pass linear losses associated with the cavity. However, calculations based on these higher losses are in good agreement with the experimentally determined values. In additions, a factor of 1.65 increase in the second harmonic output power is anticipated by reducing the input mirror reflectivity to better impedance-match the cavity. With this relatively low second harmonic conversion, the power to light conversion is 7.8%.

  10. Establishment of a Digital Knowledge Conversion Architecture Design Learning with High User Acceptance

    ERIC Educational Resources Information Center

    Wu, Yun-Wu; Weng, Apollo; Weng, Kuo-Hua

    2017-01-01

    The purpose of this study is to design a knowledge conversion and management digital learning system for architecture design learning, helping students to share, extract, use and create their design knowledge through web-based interactive activities based on socialization, internalization, combination and externalization process in addition to…

  11. A high-resolution and one-cycle conversion time-to-digital converter architecture for PET image applications.

    PubMed

    Sheng, Duo; Chung, Ching-Che; Huang, Chih-Chung; Jian, Jia-Wei

    2013-01-01

    In this paper, a high-resolution and one-cycle conversion time-to-digital converter (TDC) architecture with cell-based design for positron emission tomography (PET) applications is presented. The proposed TDC employs a cascade-stage structure to achieve high timing resolution and wide sampling range at the same time. Besides, based on the proposed two-level conversion structure, the proposed TDC not only can achieve single cycle latency and high speed of operation, but also have low circuit complexity as compared with conventional approaches. Simulation results show that operation frequency of the proposed TDC can be improved to 200 MHz with 50 ps resolution. In addition, the proposed TDC can be implemented with standard cells, making it easily portable to different processes and very suitable for biomedical chip applications.

  12. Automated frame selection process for high-resolution microendoscopy

    PubMed Central

    Ishijima, Ayumu; Schwarz, Richard A.; Shin, Dongsuk; Mondrik, Sharon; Vigneswaran, Nadarajah; Gillenwater, Ann M.; Anandasabapathy, Sharmila; Richards-Kortum, Rebecca

    2015-01-01

    Abstract. We developed an automated frame selection algorithm for high-resolution microendoscopy video sequences. The algorithm rapidly selects a representative frame with minimal motion artifact from a short video sequence, enabling fully automated image analysis at the point-of-care. The algorithm was evaluated by quantitative comparison of diagnostically relevant image features and diagnostic classification results obtained using automated frame selection versus manual frame selection. A data set consisting of video sequences collected in vivo from 100 oral sites and 167 esophageal sites was used in the analysis. The area under the receiver operating characteristic curve was 0.78 (automated selection) versus 0.82 (manual selection) for oral sites, and 0.93 (automated selection) versus 0.92 (manual selection) for esophageal sites. The implementation of fully automated high-resolution microendoscopy at the point-of-care has the potential to reduce the number of biopsies needed for accurate diagnosis of precancer and cancer in low-resource settings where there may be limited infrastructure and personnel for standard histologic analysis. PMID:25919426

  13. Automated frame selection process for high-resolution microendoscopy

    NASA Astrophysics Data System (ADS)

    Ishijima, Ayumu; Schwarz, Richard A.; Shin, Dongsuk; Mondrik, Sharon; Vigneswaran, Nadarajah; Gillenwater, Ann M.; Anandasabapathy, Sharmila; Richards-Kortum, Rebecca

    2015-04-01

    We developed an automated frame selection algorithm for high-resolution microendoscopy video sequences. The algorithm rapidly selects a representative frame with minimal motion artifact from a short video sequence, enabling fully automated image analysis at the point-of-care. The algorithm was evaluated by quantitative comparison of diagnostically relevant image features and diagnostic classification results obtained using automated frame selection versus manual frame selection. A data set consisting of video sequences collected in vivo from 100 oral sites and 167 esophageal sites was used in the analysis. The area under the receiver operating characteristic curve was 0.78 (automated selection) versus 0.82 (manual selection) for oral sites, and 0.93 (automated selection) versus 0.92 (manual selection) for esophageal sites. The implementation of fully automated high-resolution microendoscopy at the point-of-care has the potential to reduce the number of biopsies needed for accurate diagnosis of precancer and cancer in low-resource settings where there may be limited infrastructure and personnel for standard histologic analysis.

  14. Selection of DNA aptamers against epidermal growth factor receptor with high affinity and specificity

    SciTech Connect

    Wang, Deng-Liang; Song, Yan-Ling; Zhu, Zhi; Li, Xi-Lan; Zou, Yuan; Yang, Hai-Tao; Wang, Jiang-Jie; Yao, Pei-Sen; Pan, Ru-Jun; Yang, Chaoyong James; Kang, De-Zhi

    2014-10-31

    Highlights: • This is the first report of DNA aptamer against EGFR in vitro. • Aptamer can bind targets with high affinity and selectivity. • DNA aptamers are more stable, cheap and efficient than RNA aptamers. • Our selected DNA aptamer against EGFR has high affinity with K{sub d} 56 ± 7.3 nM. • Our selected DNA aptamer against EGFR has high selectivity. - Abstract: Epidermal growth factor receptor (EGFR/HER1/c-ErbB1), is overexpressed in many solid cancers, such as epidermoid carcinomas, malignant gliomas, etc. EGFR plays roles in proliferation, invasion, angiogenesis and metastasis of malignant cancer cells and is the ideal antigen for clinical applications in cancer detection, imaging and therapy. Aptamers, the output of the systematic evolution of ligands by exponential enrichment (SELEX), are DNA/RNA oligonucleotides which can bind protein and other substances with specificity. RNA aptamers are undesirable due to their instability and high cost of production. Conversely, DNA aptamers have aroused researcher’s attention because they are easily synthesized, stable, selective, have high binding affinity and are cost-effective to produce. In this study, we have successfully identified DNA aptamers with high binding affinity and selectivity to EGFR. The aptamer named TuTu22 with K{sub d} 56 ± 7.3 nM was chosen from the identified DNA aptamers for further study. Flow cytometry analysis results indicated that the TuTu22 aptamer was able to specifically recognize a variety of cancer cells expressing EGFR but did not bind to the EGFR-negative cells. With all of the aforementioned advantages, the DNA aptamers reported here against cancer biomarker EGFR will facilitate the development of novel targeted cancer detection, imaging and therapy.

  15. A Selective Overview of Variable Selection in High Dimensional Feature Space

    PubMed Central

    Fan, Jianqing

    2010-01-01

    High dimensional statistical problems arise from diverse fields of scientific research and technological development. Variable selection plays a pivotal role in contemporary statistical learning and scientific discoveries. The traditional idea of best subset selection methods, which can be regarded as a specific form of penalized likelihood, is computationally too expensive for many modern statistical applications. Other forms of penalized likelihood methods have been successfully developed over the last decade to cope with high dimensionality. They have been widely applied for simultaneously selecting important variables and estimating their effects in high dimensional statistical inference. In this article, we present a brief account of the recent developments of theory, methods, and implementations for high dimensional variable selection. What limits of the dimensionality such methods can handle, what the role of penalty functions is, and what the statistical properties are rapidly drive the advances of the field. The properties of non-concave penalized likelihood and its roles in high dimensional statistical modeling are emphasized. We also review some recent advances in ultra-high dimensional variable selection, with emphasis on independence screening and two-scale methods. PMID:21572976

  16. Reconfigurable high-speed optical fibre networks: Optical wavelength conversion and switching using VCSELs to eliminate channel collisions

    NASA Astrophysics Data System (ADS)

    Boiyo, Duncan Kiboi; Chabata, T. V.; Kipnoo, E. K. Rotich; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

    2017-01-01

    We experimentally provide an alternative solution to channel collisions through up-wavelength conversion and switching by using vertical cavity surface-emitting lasers (VCSELs). This has been achieved by utilizing purely optical wavelength conversion on VCSELs at the low attenuation, 1550 nm transmission window. The corresponding transmission and bit error-rate (BER) performance evaluation is also presented. In this paper, two 1550 nm VCSELs with 50-150 GHz channel spacing are modulated with a 10 Gb/s NRZ PRBS 27-1 data and their interferences investigated. A channel interference penalty range of 0.15-1.63 dB is incurred for 150-50 GHz channel spacing without transmission. To avoid channel collisions and to minimize high interference penalties, the transmitting VCSEL with data is injected into the side-mode of a slave VCSEL to obtain a new up converted wavelength. A 16 dB extinction ratio of the incoming wavelength is achieved when a 15 dBm transmitting beam is injected into the side-mode of a -4.5 dBm slave VCSEL. At 8.5 Gb/s, a 1.1 dB conversion and a 0.5 dB transmission penalties are realized when the converted wavelength is transmitted over a 24.7 km G.655 fibre. This work offers a low-cost, effective wavelength conversion and channel switching to reduce channel collision probability by reconfiguring channels at the node of networks.

  17. High-Performance Inverted Organic Photovoltaics Without Hole-Selective Contact.

    PubMed

    Savva, Achilleas; Burgués-Ceballos, Ignasi; Papazoglou, Giannis; Choulis, Stelios A

    2015-11-11

    A detailed investigation of the functionality of inverted organic photovoltaics (OPVs) using bare Ag contacts as the top electrode is presented. The inverted OPVs without a hole-transporting layer (HTL) exhibit a significant gain in hole-carrier selectivity and power-conversion efficiency (PCE) after exposure in ambient conditions. Inverted OPVs comprised of ITO-ZnO-poly(3-hexylthiophene-2,5-diyl)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM)-Ag demonstrate over 3.5% power conversion efficiency only if the devices are exposed in air for over 4 days. As concluded through a series of measurements, the oxygen presence is essential to obtaining fully operational solar cell devices without HTL. Moreover, accelerated stability tests under damp heat conditions (RH = 85% and T = 65 °C) performed to nonencapsulated OPVs demonstrate that HTL-free inverted OPVs exhibit comparable stability to the reference inverted OPVs. Importantly, it is shown that bare Ag top electrodes can be efficiently used in inverted OPVs using various high-performance polymer-fullerene bulk heterojunction material systems demonstrating 6.5% power-conversion efficiencies.

  18. High-Performance Inverted Organic Photovoltaics Without Hole-Selective Contact

    PubMed Central

    2015-01-01

    A detailed investigation of the functionality of inverted organic photovoltaics (OPVs) using bare Ag contacts as the top electrode is presented. The inverted OPVs without a hole-transporting layer (HTL) exhibit a significant gain in hole-carrier selectivity and power-conversion efficiency (PCE) after exposure in ambient conditions. Inverted OPVs comprised of ITO–ZnO–poly(3-hexylthiophene-2,5-diyl)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM)–Ag demonstrate over 3.5% power conversion efficiency only if the devices are exposed in air for over 4 days. As concluded through a series of measurements, the oxygen presence is essential to obtaining fully operational solar cell devices without HTL. Moreover, accelerated stability tests under damp heat conditions (RH = 85% and T = 65 °C) performed to nonencapsulated OPVs demonstrate that HTL-free inverted OPVs exhibit comparable stability to the reference inverted OPVs. Importantly, it is shown that bare Ag top electrodes can be efficiently used in inverted OPVs using various high-performance polymer–fullerene bulk heterojunction material systems demonstrating 6.5% power-conversion efficiencies. PMID:26468993

  19. Super-surface selective nanomembranes providing simultaneous high permeation flux and high selectivity

    DOEpatents

    Hu, Michael Z.; Simpson, John T.; Aytug, Tolga; Paranthaman, Mariappan Parans; Sturgeon, Matthew R.

    2016-04-12

    Superhydrophobic membrane structures having a beneficial combination of throughput and a selectivity. The membrane structure can include a porous support substrate; and a membrane layer adherently disposed on and in contact with the porous support substrate. The membrane layer can include a nanoporous material having a superhydrophobic surface. The superhydrophobic surface can include a textured surface, and a modifying material disposed on the textured surface. Methods of making and using the membrane structures.

  20. EDITORIAL: Special issue for papers selected from The 8th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2008) Special issue for papers selected from The 8th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2008)

    NASA Astrophysics Data System (ADS)

    Tanaka, Shuji

    2009-09-01

    This special issue of the Journal of Micromechanics and Microengineering features papers selected from The 8th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2008) with the 2nd Symposium on Micro Environmental Machine Systems (μMEMS 2008). The workshop was held in Sendai, Japan on 9-12 November 2008 by Tohoku University. This is the second time that the PowerMEMS workshop has been held in Sendai, following the first workshop in 2000. Power MEMS is one of the newest categories of MEMS, which encompasses microdevices and microsystems for power generation, energy conversion and propulsion. The first concept of Power MEMS was born in the late 1990's from a MEMS-based gas turbine project at Massachusetts Institute of Technology. After that, the research and development of Power MEMS have been promoted by the strong need for compact power sources with high energy and/or power density. Since its inception, Power MEMS has expanded to include not only various MEMS-based power generators but also small energy machines and microdevices for macro power generators. Previously, the main topics of the PowerMEMS workshop were miniaturized gas turbines and micro fuel cells, but recently, energy harvesting has been the hottest topic. In 2008, energy harvesting had a 41% share in the 118 accepted regular papers. This special issue includes 19 papers on various topics. Finally, I would like to express my sincere appreciation to the members of the International Steering Committee, the Technical Program Committee, the Local Organizing Committee and financial supporters. This special issue was edited in collaboration with the staff of IOP Publishing.

  1. Modified high-accuracy 3D shape data conversion system for reverse engineering applications

    NASA Astrophysics Data System (ADS)

    Sitnik, Robert; Kujawinska, Malgorzata

    2001-10-01

    In the paper the sequential steps of reverse engineering based on the data gathered by full-field optical system are discussed. The compete conversion process of a cloud of point coordinates to CAD/CAM is presented. The triangulation algorithm, which automatically creates the triangle mesh from the input cloud of points is described. Each block of this algorithm is explained din details with special attention paid to the parameters controlling the quality of the data conversion process. The adaptive process of reducing the number of the triangles on the base of second derivative of local curvature of objects' surface is explained. The error analysis is discussed at each step of the cloud data processing in dependency of the algorithm initial parameters.

  2. High Photoelectric Conversion Efficiency of Metal Phthalocyanine/Fullerene Heterojunction Photovoltaic Device

    PubMed Central

    Lin, Chi-Feng; Zhang, Mi; Liu, Shun-Wei; Chiu, Tien-Lung; Lee, Jiun-Haw

    2011-01-01

    This paper introduces the fundamental physical characteristics of organic photovoltaic (OPV) devices. Photoelectric conversion efficiency is crucial to the evaluation of quality in OPV devices, and enhancing efficiency has been spurring on researchers to seek alternatives to this problem. In this paper, we focus on organic photovoltaic (OPV) devices and review several approaches to enhance the energy conversion efficiency of small molecular heterojunction OPV devices based on an optimal metal-phthalocyanine/fullerene (C60) planar heterojunction thin film structure. For the sake of discussion, these mechanisms have been divided into electrical and optical sections: (1) Electrical: Modification on electrodes or active regions to benefit carrier injection, charge transport and exciton dissociation; (2) Optical: Optional architectures or infilling to promote photon confinement and enhance absorption. PMID:21339999

  3. Balance of oxygen throughout the conversion of a high-level waste melter feed to glass

    DOE PAGES

    Lee, SeungMin; Hrma, Pavel; Kloužek, Jaroslav; ...

    2017-07-03

    Gases evolve from nuclear waste melter feed during conversion to glass in response to heating. This article is focused on oxygen mass balance based on the stoichiometry of feed melting reactions and evolved-gas analysis data. Whereas O2-producing and -consuming batch-melting reactions are complete in the reacting and primary-foam layers of the cold cap, O2 from redox reactions continues to evolve as long as melt temperature increases, and thus generates secondary foam. Also, we discuss the relationship between the oxygen mass balance and the temperature-dependent iron redox ratio and the O2 partial pressure, as they evolve during the feed-to-glass conversion.

  4. Direct conversion of chicory flour into L(+)-lactic acid by the highly effective inulinase producer Lactobacillus paracasei DSM 23505.

    PubMed

    Petrova, Penka; Velikova, Petya; Popova, Luiza; Petrov, Kaloyan

    2015-06-01

    Highly effective bio-process for lactic acid (LA) production by simultaneous saccharification and fermentation (SSF) of chicory flour was developed. The strain used, Lactobacillus paracasei DSM 23505 produced natural inulinase (EC 3.2.1.80) with molecular weight ∼130 kDa, located in the cell wall fraction. In batch fermentation with optimized medium content and fermentation conditions, a complete conversion of 136 g/L chicory flour (89.3% inulin and 10.7% mix of sucrose, fructose and glucose) into 123.7 g/L LA was achieved. These yield and conversion rate are the highest obtained by SSF for LA production from inulin. The high efficiency, the cheap fermentation broth and the simple process performance disclose the promising use of the chicory flour in industrial biotechnology for LA production.

  5. Selective conversion of plasma glucose into CO2 by Saccharomyces cerevisiae for the measurement of 13C abundance by isotope ratio mass spectrometry: proof of principle.

    PubMed

    Rembacz, Krzysztof P; Faber, Klaas Nico; Stellaard, Frans

    2007-01-01

    To study carbohydrate digestion and glucose absorption, time-dependent (13)C enrichment in plasma glucose is measured after oral administration of naturally occurring (13)C-enriched carbohydrates. The isotope enrichment of the administered carbohydrate is low (APE <0.1%) and plasma (13)C glucose measurements are routinely determined with gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) or liquid chromatography/combustion/isotope ratio mass spectrometry (LC/C/IRMS). In this study, plasma glucose was converted into CO(2) by an in-tube reaction with yeast permitting direct measurement of (13)CO(2) in the headspace. Saccharomyces cerevisiae incubated under anaerobic conditions was able to convert sufficient glucose into CO(2) to produce a consistent CO(2) peak in IRMS with little variation in peak area and precise delta(13)C(PDB) values for corn glucose: -11.40 +/- 0.16 per thousand, potato glucose: -25.17 +/- 0.13 per thousand, and plasma glucose: -26.29 +/- 0.05 per thousand. The measurement showed high linearity (R(2) = 0.999) and selectivity and was not affected by the glucose concentration in the tested range of 5-15 mM. Comparison with GC/C/IRMS showed a good correlation of enrichment data: R(2) > 0.98 for both sources of glucose and plasma samples. Commercially available, instant dried baker's yeast was qualitatively and quantitatively comparable with freshly prepared yeast: R(2) > 0.96, slope 1.03 and 1.08 for glucose solutions and plasma, respectively. Thus, yeast conversion of plasma glucose into CO(2) and (13)C measurement applying a breath (13)CO(2) analyzer is an inexpensive, simple and equally accurate alternative to the more expensive and laborious GC/C/IRMS and LC/C/IRMS measurements. Copyright (c) 2007 John Wiley & Sons, Ltd.

  6. An ant-plant by-product mutualism is robust to selective logging of rain forest and conversion to oil palm plantation.

    PubMed

    Fayle, Tom M; Edwards, David P; Foster, William A; Yusah, Kalsum M; Turner, Edgar C

    2015-06-01

    Anthropogenic disturbance and the spread of non-native species disrupt natural communities, but also create novel interactions between species. By-product mutualisms, in which benefits accrue as side effects of partner behaviour or morphology, are often non-specific and hence may persist in novel ecosystems. We tested this hypothesis for a two-way by-product mutualism between epiphytic ferns and their ant inhabitants in the Bornean rain forest, in which ants gain housing in root-masses while ferns gain protection from herbivores. Specifically, we assessed how the specificity (overlap between fern and ground-dwelling ants) and the benefits of this interaction are altered by selective logging and conversion to an oil palm plantation habitat. We found that despite the high turnover of ant species, ant protection against herbivores persisted in modified habitats. However, in ferns growing in the oil palm plantation, ant occupancy, abundance and species richness declined, potentially due to the harsher microclimate. The specificity of the fern-ant interactions was also lower in the oil palm plantation habitat than in the forest habitats. We found no correlations between colony size and fern size in modified habitats, and hence no evidence for partner fidelity feedbacks, in which ants are incentivised to protect fern hosts. Per species, non-native ant species in the oil palm plantation habitat (18 % of occurrences) were as important as native ones in terms of fern protection and contributed to an increase in ant abundance and species richness with fern size. We conclude that this by-product mutualism persists in logged forest and oil palm plantation habitats, with no detectable shift in partner benefits. Such persistence of generalist interactions in novel ecosystems may be important for driving ecosystem functioning.

  7. Conversion and Blending Facility highly enriched uranium to low enriched uranium as metal. Revision 1

    SciTech Connect

    1995-07-05

    The mission of this Conversion and Blending Facility (CBF) will be to blend surplus HEU metal and alloy with depleted uranium metal to produce an LEU product. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. The blended LEU will be produced as a waste suitable for storage or disposal.

  8. On-demand superradiant conversion of atomic spin gratings into single photons with high efficiency.

    PubMed

    Black, Adam T; Thompson, James K; Vuletić, Vladan

    2005-09-23

    We create quantized spin gratings by single-photon detection and convert them on demand into photons with retrieval efficiencies exceeding 40% (80%) for single (a few) quanta. We show that the collective conversion process, proceeding via superradiant emission into a moderate-finesse optical resonator, requires phase matching. The storage time of 3 micros in the cold-atom sample, as well as the peak retrieval efficiency, are likely limited by Doppler decoherence of the entangled state.

  9. Fungal Enzymes and Yeasts for Conversion of Plant Biomass to Bioenergy and High-Value Products.

    PubMed

    Lange, Lene

    2017-01-01

    Fungi and fungal enzymes play important roles in the new bioeconomy. Enzymes from filamentous fungi can unlock the potential of recalcitrant lignocellulose structures of plant cell walls as a new resource, and fungi such as yeast can produce bioethanol from the sugars released after enzyme treatment. Such processes reflect inherent characteristics of the fungal way of life, namely, that fungi as heterotrophic organisms must break down complex carbon structures of organic materials to satisfy their need for carbon and nitrogen for growth and reproduction. This chapter describes major steps in the conversion of plant biomass to value-added products. These products provide a basis for substituting fossil-derived fuels, chemicals, and materials, as well as unlocking the biomass potential of the agricultural harvest to yield more food and feed. This article focuses on the mycological basis for the fungal contribution to biorefinery processes, which are instrumental for improved resource efficiency and central to the new bioeconomy. Which types of processes, inherent to fungal physiology and activities in nature, are exploited in the new industrial processes? Which families of the fungal kingdom and which types of fungal habitats and ecological specializations are hot spots for fungal biomass conversion? How can the best fungal enzymes be found and optimized for industrial use? How can they be produced most efficiently-in fungal expression hosts? How have industrial biotechnology and biomass conversion research contributed to mycology and environmental research? Future perspectives and approaches are listed, highlighting the importance of fungi in development of the bioeconomy.

  10. High conversion of HAuCl4 into gold nanorods: A re-seeding approach.

    PubMed

    Canonico-May, Stephanie Ann; Beavers, Kelsey Ross; Melvin, Michael James; Alkilany, Alaaldin M; Duvall, Craig L; Stone, John William

    2016-02-01

    Gold nanorods with varying aspect ratios have been utilized in recent years for a wide range of applications including vaccines, surface enhanced Raman spectroscopy (SERS) substrates, and as medicinal therapeutic agents. The surfactant-directed seed mediated approach is an aqueous based protocol that produces monodisperse nanorods with controlled aspect ratios. However, an inherent problem with this approach is poor efficiency of gold conversion from HAuCl4 into nanorods. In fact only ∼15% of gold is converted, motivating the need for alternate synthetic protocols in order to make the process more scalable and efficient as gold nanorods progress toward commercial applications. In the current study, we have significantly improved this conversion by growing rods in several iterations of supernatant solutions that were previously discarded as waste. Inductively coupled plasma mass spectrometry (ICP-MS) data indicates ∼14% gold conversion per nanorod solution with a total recovery of ∼75%. Gold nanorods prepared in consecutive supernatant solutions generally have slightly increased aspect ratios and maintain stability and monodispersity as measured by UV-vis and TEM. The increased nanorod yield minimizes gold waste and results in a greener synthetic approach.

  11. Fabrication of hollow spheres by dry-gel conversion and its application in the selective hydrodesulfurization of FCC gasoline.

    PubMed

    Zhang, Jinchang; Wang, Gang; Jin, Fengying; Fang, Xiangchen; Song, Chunshan; Guo, Xinwen

    2013-04-15

    Hollow spheres were synthesized from MCM-41 solid spheres by dry-gel conversion. It was found that water amount has a major impact on the formation of hollow spheres. Transmission electron microscopy (TEM) images revealed that the hollow spheres are between 500 and 600 nm in size with a dense shell of ca. 100 nm. The synthesized hollow sphere sample was examined as a support for hydrodesulfurization catalyst. The sulfur removal was enhanced while olefin hydrogenation of FCC gasoline was suppressed, and thus, the octane value was preserved when the hollow spheres (Na type) were loaded with Ni and Mo oxides as catalyst.

  12. Unidirectional radiative heat transfer with a spectrally selective planar absorber/emitter for high-efficiency solar thermophotovoltaic systems

    NASA Astrophysics Data System (ADS)

    Kohiyama, Asaka; Shimizu, Makoto; Yugami, Hiroo

    2016-11-01

    A high-efficiency solar thermophotovoltaic (STPV) system has been demonstrated using spectrally selective planar absorber/emitter systems and a GaSb TPV cell. In this study, a novel approach for designing the STPV system based on the efficiency of unidirectional radiative heat transfer has been introduced. To achieve high extraction and photovoltaic conversion efficiencies, the spectrally selective absorber/emitter based on a coherent perfect absorber composed of a thin molybdenum layer sandwiched between hafnium layers was applied. The extraction efficiency was further investigated with respect to the absorber/emitter area ratio. The experimental efficiency of STPV reached 5.1% with the area ratio of 2.3.

  13. Analysis of 62 hybrid assembled human Y chromosomes exposes rapid structural changes and high rates of gene conversion

    PubMed Central

    Schierup, Mikkel Heide

    2017-01-01

    The human Y-chromosome does not recombine across its male-specific part and is therefore an excellent marker of human migrations. It also plays an important role in male fertility. However, its evolution is difficult to fully understand because of repetitive sequences, inverted repeats and the potentially large role of gene conversion. Here we perform an evolutionary analysis of 62 Y-chromosomes of Danish descent sequenced using a wide range of library insert sizes and high coverage, thus allowing large regions of these chromosomes to be well assembled. These include 17 father-son pairs, which we use to validate variation calling. Using a recent method that can integrate variants based on both mapping and de novo assembly, we genotype 10898 SNVs and 2903 indels (max length of 27241 bp) in our sample and show by father-son concordance and experimental validation that the non-recurrent SNP and indel variation on the Y chromosome tree is called very accurately. This includes variation called in a 0.9 Mb centromeric heterochromatic region, which is by far the most variable in the Y chromosome. Among the variation is also longer sequence-stretches not present in the reference genome but shared with the chimpanzee Y chromosome. We analyzed 2.7 Mb of large inverted repeats (palindromes) for variation patterns among the two palindrome arms and identified 603 mutation and 416 gene conversions events. We find clear evidence for GC-biased gene conversion in the palindromes (and a balancing AT mutation bias), but irrespective of this, also a strong bias towards gene conversion towards the ancestral state, suggesting that palindromic gene conversion may alleviate Muller’s ratchet. Finally, we also find a large number of large-scale gene duplications and deletions in the palindromic regions (at least 24) and find that such events can consist of complex combinations of simultaneous insertions and deletions of long stretches of the Y chromosome. PMID:28846694

  14. Analysis of 62 hybrid assembled human Y chromosomes exposes rapid structural changes and high rates of gene conversion.

    PubMed

    Skov, Laurits; Schierup, Mikkel Heide

    2017-08-01

    The human Y-chromosome does not recombine across its male-specific part and is therefore an excellent marker of human migrations. It also plays an important role in male fertility. However, its evolution is difficult to fully understand because of repetitive sequences, inverted repeats and the potentially large role of gene conversion. Here we perform an evolutionary analysis of 62 Y-chromosomes of Danish descent sequenced using a wide range of library insert sizes and high coverage, thus allowing large regions of these chromosomes to be well assembled. These include 17 father-son pairs, which we use to validate variation calling. Using a recent method that can integrate variants based on both mapping and de novo assembly, we genotype 10898 SNVs and 2903 indels (max length of 27241 bp) in our sample and show by father-son concordance and experimental validation that the non-recurrent SNP and indel variation on the Y chromosome tree is called very accurately. This includes variation called in a 0.9 Mb centromeric heterochromatic region, which is by far the most variable in the Y chromosome. Among the variation is also longer sequence-stretches not present in the reference genome but shared with the chimpanzee Y chromosome. We analyzed 2.7 Mb of large inverted repeats (palindromes) for variation patterns among the two palindrome arms and identified 603 mutation and 416 gene conversions events. We find clear evidence for GC-biased gene conversion in the palindromes (and a balancing AT mutation bias), but irrespective of this, also a strong bias towards gene conversion towards the ancestral state, suggesting that palindromic gene conversion may alleviate Muller's ratchet. Finally, we also find a large number of large-scale gene duplications and deletions in the palindromic regions (at least 24) and find that such events can consist of complex combinations of simultaneous insertions and deletions of long stretches of the Y chromosome.

  15. Biocatalytic conversion of lignocellulose to platform chemicals.

    PubMed

    Jäger, Gernot; Büchs, Jochen

    2012-09-01

    Naturally occurring lignocellulose can be used as a renewable resource for the sustainable production of platform chemicals that can in turn be converted to valuable fine chemicals, polymers, and fuels. The biocatalytic conversion of lignocellulose is a very promising approach due to its high selectivity, mild conditions, and low exergy loss. However, such biocatalytic processes are still seldom applied at the industrial scale since the single conversion steps (pretreatment, hydrolysis, and fermentation) may exhibit low conversion rates, low efficiencies, or high costs. The biocatalytic conversion of lignocellulose to platform chemicals is reviewed in this work. Structures and production rates of lignocellulose are described, and platform chemicals that may be produced from lignocellulose are summarized. Biocatalytic conversion of lignocellulose is distinguished from conventional non-selective approaches. All essential conversion steps used in biocatalytic approaches (pretreatment, hydrolysis, and fermentation) are reviewed in detail. Finally, potential interactions between these conversion steps are highlighted and the advantages as well as disadvantages of integrated process configurations are elucidated. In conclusion, a comprehensive understanding of the biocatalytic conversion of lignocellulose is provided in this review.

  16. The roles of gene duplication, gene conversion and positive selection in rodent Esp and Mup pheromone gene families with comparison to the Abp family.

    PubMed

    Karn, Robert C; Laukaitis, Christina M

    2012-01-01

    Three proteinaceous pheromone families, the androgen-binding proteins (ABPs), the exocrine-gland secreting peptides (ESPs) and the major urinary proteins (MUPs) are encoded by large gene families in the genomes of Mus musculus and Rattus norvegicus. We studied the evolutionary histories of the Mup and Esp genes and compared them with what is known about the Abp genes. Apparently gene conversion has played little if any role in the expansion of the mouse Class A and Class B Mup genes and pseudogenes, and the rat Mups. By contrast, we found evidence of extensive gene conversion in many Esp genes although not in all of them. Our studies of selection identified at least two amino acid sites in β-sheets as having evolved under positive selection in the mouse Class A and Class B MUPs and in rat MUPs. We show that selection may have acted on the ESPs by determining K(a)/K(s) for Exon 3 sequences with and without the converted sequence segment. While it appears that purifying selection acted on the ESP signal peptides, the secreted portions of the ESPs probably have undergone much more rapid evolution. When the inner gene converted fragment sequences were removed, eleven Esp paralogs were present in two or more pairs with K(a)/K(s) >1.0 and thus we propose that positive selection is detectable by this means in at least some mouse Esp paralogs. We compare and contrast the evolutionary histories of all three mouse pheromone gene families in light of their proposed functions in mouse communication.

  17. Technical basis in support of the conversion of the University of Missouri Research Reactor (MURR) core from highly-enriched to low-enriched uranium - core neutron physics

    SciTech Connect

    Stillman, J.; Feldman, E.; Foyto, L; Kutikkad, K; McKibben, J C; Peters, N.; Stevens, J.

    2012-09-01

    This report contains the results of reactor design and performance for conversion of the University of Missouri Research Reactor (MURR) from the use of highly-enriched uranium (HEU) fuel to the use of low-enriched uranium (LEU) fuel. The analyses were performed by staff members of the Global Threat Reduction Initiative (GTRI) Reactor Conversion Program at the Argonne National Laboratory (ANL) and the MURR Facility. The core conversion to LEU is being performed with financial support of the U. S. government.

  18. Conversational Dominance.

    ERIC Educational Resources Information Center

    Esau, Helmut; Poth, Annette

    Details of conversational behavior can often not be interpreted until the social interaction, including the rights and obligations of the participants, their intent, the topic, etc., has been defined. This paper presents a model of conversation in which the conversational image a person presents in a given conversational situation is a function of…

  19. Proteins responsible for lysogenic conversion caused by coliphages N15 and phi80 are highly homologous.

    PubMed Central

    Vostrov, A A; Vostrukhina, O A; Svarchevsky, A N; Rybchin, V N

    1996-01-01

    Lysogenic conversion caused by lambdoid bacteriophage phi80 and that caused by coliphage N15 have similar characteristics, suggesting that similarities in their cor genes and Cor proteins are responsible for this effect. Here we present the nucleotide sequence of the N15 cor gene. The N15 cor gene homolog was found in the phi80 cor region, but in the opposite direction of that of the open reading frame to which the phi80 cor gene had previously been assigned (M. Matsumoto, N. Ichikawa, S. Tanaka, T. Morita, and A. Matsushiro, Jpn. J. Genet. 60:475-483, 1985). PMID:8631731

  20. Synthesis of porous zinc gallate prisms composed of highly oriented nanoparticles by an in situ conversion reaction.

    PubMed

    Zhou, Wenli; Yang, Xianfeng; Huang, Lin; Wang, Jing; Tang, Jinke; Liang, Hongbin

    2012-04-23

    Porous ZnGa(2)O(4) prisms assembled by highly oriented nanoparticles have been fabricated by an in situ chemical conversion approach. We report, for the first time, that a solid α-Ga(2)O(3) precursor can be directly converted into ZnGa(2)O(4) rather than through the intermediate GaOOH. Based on a detailed study of the evolution of ZnGa(2)O(4) prisms, a growth mechanism is proposed for the in situ conversion reaction. During this conversion process, the precursor morphology can be highly retained, which is attributed to the similar atomic arrangements of the Ga and O atoms and excellent matching of the lattice spacing between the α-Ga(2)O(3) and ZnGa(2)O(4) prisms. The direct reaction between the precursor α-Ga(2)O(3) and Zn(2+) ions is more efficient than that between the byproduct GaOOH and Zn(2+) ions. Moreover, the photoluminescent color of the ZnGa(2)O(4) phosphor can be tuned by doping with Mn(2+) ions. Efficient energy transfer (ET) from the host lattice to the Mn(2+) centers is observed, whereas ET from the defects to the Mn(2+) ions is prohibited. The fabricated ZnGa(2)O(4) products have potential in the field of display applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Perovskite for the highly selective enrichment of phosphopeptides.

    PubMed

    Li, Xiao-Shui; Chen, Xi; Sun, Huan; Yuan, Bi-Feng; Feng, Yu-Qi

    2015-01-09

    Selective and effective enrichment of phosphopeptides from complex samples is essential in phosphoproteome study by mass spectrometry (MS). In this work, we compared perovskites (MgTiO3, CaTiO3, SrTiO3, BaTiO3 and CaZrO3) with metal oxides (ZrO2 and TiO2) in their capability for the selective enrichment of phosphopeptides. It was found here that perovskites exhibited higher selectivity towards phosphopeptides than commonly used ZrO2 and TiO2, even though they all have high affinity to phosphopeptides. As for perovskites, CaTiO3 exhibited better selectivity for enrichment of phosphopeptides than SrTiO3, MgTiO3, BaTiO3 and CaZrO3, which might be ascribed to their crystal structures and electrophilic abilities. Moreover, to further confirm the performance of CaTiO3, CaTiO3 and TiO2 were applied to the enrichment of phosphopeptides from tryptic digest of proteins of human Jurkat-T cell lysate, respectively. The results showed CaTiO3 has much higher selectivity than TiO2 in the enrichment of phosphopeptides from the complex biological sample. Taken together, here we show that CaTiO3 is an excellent material for the highly selective enrichment of phosphopeptides and it could be potentially used in the large-scale phosphoproteome study.

  2. High-order optical vortex generation in a few-mode fiber via cascaded acoustically driven vector mode conversion.

    PubMed

    Zhang, Wending; Huang, Ligang; Wei, Keyan; Li, Peng; Jiang, Biqiang; Mao, Dong; Gao, Feng; Mei, Ting; Zhang, Guoquan; Zhao, Jianlin

    2016-11-01

    We propose a method to generate the high-order optical vortex in a few-mode fiber via cascaded acoustically driven vector mode conversion. Theoretical analysis showed that the vector mode conversion induced by the acoustically induced fiber grating (AIFG) could occur between two HE modes with adjacent azimuthal numbers. In the experiment conducted at 532 nm, two AIFGs were simultaneously induced in the same segment of the fiber by a radio frequency source containing two different frequency components. One AIFG was used to convert the left- and right-handed circular polarization fundamental modes to the ±1-order vortex modes, which were then further converted to the ±2-order vortex modes by the other AIFG. The topological charges of the vortex modes were verified using both coaxial and off-axial interference methods, showing typical signature patterns of spiral forms and forklike fringes, respectively.

  3. Efficient continuous-wave nonlinear frequency conversion in high-Q gallium nitride photonic crystal cavities on silicon

    NASA Astrophysics Data System (ADS)

    Mohamed, Mohamed Sabry; Simbula, Angelica; Carlin, Jean-François; Minkov, Momchil; Gerace, Dario; Savona, Vincenzo; Grandjean, Nicolas; Galli, Matteo; Houdré, Romuald

    2017-03-01

    We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG) and third harmonic generation (THG) in suspended gallium nitride slab photonic crystal (PhC) cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4 × 104, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving a normalized conversion efficiency of 2.4 × 10-3 W-1, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.

  4. High energy conversion efficiency in laser-proton acceleration by controlling laser-energy deposition onto thin foil targets

    NASA Astrophysics Data System (ADS)

    Brenner, C. M.; Robinson, A. P. L.; Markey, K.; Scott, R. H. H.; Gray, R. J.; Rosinski, M.; Deppert, O.; Badziak, J.; Batani, D.; Davies, J. R.; Hassan, S. M.; Lancaster, K. L.; Li, K.; Musgrave, I. O.; Norreys, P. A.; Pasley, J.; Roth, M.; Schlenvoigt, H.-P.; Spindloe, C.; Tatarakis, M.; Winstone, T.; Wolowski, J.; Wyatt, D.; McKenna, P.; Neely, D.

    2014-02-01

    An all-optical approach to laser-proton acceleration enhancement is investigated using the simplest of target designs to demonstrate application-relevant levels of energy conversion efficiency between laser and protons. Controlled deposition of laser energy, in the form of a double-pulse temporal envelope, is investigated in combination with thin foil targets in which recirculation of laser-accelerated electrons can lead to optimal conditions for coupling laser drive energy into the proton beam. This approach is shown to deliver a substantial enhancement in the coupling of laser energy to 5-30 MeV protons, compared to single pulse irradiation, reaching a record high 15% conversion efficiency with a temporal separation of 1 ps between the two pulses and a 5 μm-thick Au foil. A 1D simulation code is used to support and explain the origin of the observation of an optimum pulse separation of ˜1 ps.

  5. Brave New Love: The Threat of High-Tech "Conversion" Therapy and the Bio-Oppression of Sexual Minorities.

    PubMed

    Earp, Brian D; Sandberg, Anders; Savulescu, Julian

    2014-01-01

    Our understanding of the neurochemical bases of human love and attachment, as well as of the genetic, epigenetic, hormonal, and experiential factors that conspire to shape an individual's sexual orientation, is increasing exponentially. This research raises the vexing possibility that we may one day be equipped to modify such variables directly, allowing for the creation of "high-tech" conversion therapies or other suspect interventions. In this article, we discuss the ethics surrounding such a possibility, and call for the development of legal and procedural safeguards for protecting vulnerable children from the application of such technology. We also consider the more difficult case of voluntary, adult "conversion" and argue that in rare cases, such attempts might be permissible under strict conditions.

  6. Controlling size, amount, and crystalline structure of nanoparticles deposited on graphenes for highly efficient energy conversion and storage.

    PubMed

    Choi, Bong Gill; Park, Ho Seok

    2012-04-01

    A facilitated electrochemical reaction at the surface of electrodes is crucial for highly efficient energy conversion and storage. Herein, various nanoparticles (NPs) including Au, Pt, Pd, Ru, and RuO(2), were synthesized in situ and directly deposited on the ionic liquid (IL)-functionalized reduced graphene oxides (RGOs) in a controlled manner. The size, amount, and crystalline structures of discrete NPs were readily controlled, giving rise to enhanced methanol oxidation and pseudocapacitance. The well-defined nanostructure of decorated NPs and the favorable interaction between ILs and RGOs (or NPs) facilitated the electrochemical reaction, where NPs acted as electrocatalysts for energy conversion and played the role of redox-active electrodes for energy storage.

  7. High temperature solar selective absorber coating deposited by laser cladding

    NASA Astrophysics Data System (ADS)

    Pang, Xuming

    2017-09-01

    In order to prepare high temperature stability cermets solar selective absorbing coating, single- layer Ni/Mo–TiC cermets coatings were firstly deposited on stainless steel substrate using laser cladding method and surface coating method. The result shows that the performance of the laser cladding coating is far superior to the coating fabricated by the surface coating method with thermal emittance decreased from 44.6% to 5.5%. Furthermore, the spectrally selective coating fabricated by laser cladding shows the excellent thermal stability. The solar absorptance and thermal emittance of the coating are 80.7% and 6.0% at 600 °C, 80% and 5.5% at room temperature, respectively. This result indicates that TiC-based cermets are more propitious solar selective absorber materials. More importantly, laser cladding, as a representative of new techniques, could be applied to the field of the solar selective absorber coating.

  8. Highly selective Lewis acid sites in desilicated MFI zeolites for dihydroxyacetone isomerization to lactic acid.

    PubMed

    Dapsens, Pierre Y; Mondelli, Cecilia; Pérez-Ramírez, Javier

    2013-05-01

    Desilication of commercial MFI-type (ZSM-5) zeolites in solutions of alkali metal hydroxides is demonstrated to generate highly selective heterogeneous catalysts for the aqueous-phase isomerization of biobased dihydroxyacetone (DHA) to lactic acid (LA). The best hierarchical ZSM-5 sample attains a LA selectivity exceeding 90 %, which is comparable to that of the state-of-the-art catalyst (i.e., the Sn-beta zeolite); this optimized hierarchical catalyst is recyclable over three runs. The Lewis acid sites, which are created through desilication along with the introduction of mesoporosity, are shown to play a crucial role in the formation of the desired product; these cannot be achieved by using other post-synthetic methods, such as steaming or impregnation of aluminum species. Desilication of other metallosilicates, such as Ga-MFI, also leads to high LA selectivity. In the presence of a soluble aluminum source, such as aluminum nitrate, alkaline-assisted alumination can introduce these unique Lewis acid centers in all-silica MFI zeolites. These findings highlight the potential of zeolites in the field of biomass-to-chemical conversion, and expand the applicability of desilication for the generation of selective catalytic centers.

  9. Highly Efficient Neural Conversion of Human Pluripotent Stem Cells in Adherent and Animal‐Free Conditions

    PubMed Central

    Lukovic, Dunja; Diez Lloret, Andrea; Stojkovic, Petra; Rodríguez‐Martínez, Daniel; Perez Arago, Maria Amparo; Rodriguez‐Jimenez, Francisco Javier; González‐Rodríguez, Patricia; López‐Barneo, José; Sykova, Eva; Jendelova, Pavla; Kostic, Jelena; Moreno‐Manzano, Victoria; Stojkovic, Miodrag; Bhattacharya, Shomi S.

    2017-01-01

    Abstract Neural differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) can produce a valuable and robust source of human neural cell subtypes, holding great promise for the study of neurogenesis and development, and for treating neurological diseases. However, current hESCs and hiPSCs neural differentiation protocols require either animal factors or embryoid body formation, which decreases efficiency and yield, and strongly limits medical applications. Here we develop a simple, animal‐free protocol for neural conversion of both hESCs and hiPSCs in adherent culture conditions. A simple medium formula including insulin induces the direct conversion of >98% of hESCs and hiPSCs into expandable, transplantable, and functional neural progenitors with neural rosette characteristics. Further differentiation of neural progenitors into dopaminergic and spinal motoneurons as well as astrocytes and oligodendrocytes indicates that these neural progenitors retain responsiveness to instructive cues revealing the robust applicability of the protocol in the treatment of different neurodegenerative diseases. The fact that this protocol includes animal‐free medium and human extracellular matrix components avoiding embryoid bodies makes this protocol suitable for the use in clinic. Stem Cells Translational Medicine 2017;6:1217–1226 PMID:28213969

  10. Highly Efficient Neural Conversion of Human Pluripotent Stem Cells in Adherent and Animal-Free Conditions.

    PubMed

    Lukovic, Dunja; Diez Lloret, Andrea; Stojkovic, Petra; Rodríguez-Martínez, Daniel; Perez Arago, Maria Amparo; Rodriguez-Jimenez, Francisco Javier; González-Rodríguez, Patricia; López-Barneo, José; Sykova, Eva; Jendelova, Pavla; Kostic, Jelena; Moreno-Manzano, Victoria; Stojkovic, Miodrag; Bhattacharya, Shomi S; Erceg, Slaven

    2017-04-01

    Neural differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) can produce a valuable and robust source of human neural cell subtypes, holding great promise for the study of neurogenesis and development, and for treating neurological diseases. However, current hESCs and hiPSCs neural differentiation protocols require either animal factors or embryoid body formation, which decreases efficiency and yield, and strongly limits medical applications. Here we develop a simple, animal-free protocol for neural conversion of both hESCs and hiPSCs in adherent culture conditions. A simple medium formula including insulin induces the direct conversion of >98% of hESCs and hiPSCs into expandable, transplantable, and functional neural progenitors with neural rosette characteristics. Further differentiation of neural progenitors into dopaminergic and spinal motoneurons as well as astrocytes and oligodendrocytes indicates that these neural progenitors retain responsiveness to instructive cues revealing the robust applicability of the protocol in the treatment of different neurodegenerative diseases. The fact that this protocol includes animal-free medium and human extracellular matrix components avoiding embryoid bodies makes this protocol suitable for the use in clinic. Stem Cells Translational Medicine 2017;6:1217-1226. © 2017 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

  11. Selection and microstructures of high density uranium alloys

    SciTech Connect

    Meyer, M.K.; Trybus, C.L.; Hofman, G.L.; Frank, S.M.; Wiencek, T.C.

    1997-10-01

    Twelve uranium alloys have been selected for incorporation into very high density aluminum dispersion fuel plates for irradiation testing. These alloys are (nominally) U-10Mo, U-8Mo, U-6Mo, U-4Mo, U-9Nb-3Zr, U-6Nb-4Zr, U-5Nb-3Zr, U-2Mo-1Nb-1Zr, U-6Mo-1Pt, U-6Mo-0.6Ru, U-6Mo-0.6Si, and U-10Mo-0.05Sn. The rationale for selection of these fuels based on gamma phase stability, reports of good irradiation performance, and high uranium density will be discussed. The microstructures of these fuels were examined by SEM/EDS and XRD at three storage during the powder fabrication process. Microstructures of selected alloys are discussed.

  12. Highly functionalized 7-azaindoles as selective PPAR gamma modulators.

    PubMed

    Debenham, Sheryl D; Chan, Audrey; Lau, Fiona Waiyu; Liu, Weiguo; Wood, Harold B; Lemme, Karen; Colwell, Lawrence; Habulihaz, Bahanu; Akiyama, Taro E; Einstein, Monica; Doebber, Thomas W; Sharma, Neelam; Wang, Chaunlin F; Wu, Margaret; Berger, Joel P; Meinke, Peter T

    2008-09-01

    A series of highly functionalized 3-aroyl and 3-phenoxy-2-methyl-7-azaindoles have been identified, which are potent selective PPARgamma modulators (SPPARgammaMs). Addition of substituents at the 6-position of the 7-azaindoles improves in vitro potency and pharmacokinetics. 7-Azaindoles have significantly improved off-target profiles compared to the parent indole series.

  13. Results from selection of high redshift radio-loud quasars

    NASA Astrophysics Data System (ADS)

    Tuccillo, D.; Gonzalez-Serrano, J. I.; Carballo, R.

    2013-05-01

    We present results on reliable selection of Radio Loud Quasars (RLQ) at high redshift (z>3.6), based on the combined use of the surveys FIRST and SDSS. We explore the redshift range 3.6selected RLQ candidates by using an improved version of the Neural Network machine-learning technique similar to that in Carballo et al. (2008), that were observed and identified spectroscopically at the NOT telescope. Taking into account previous selections, these techniques lead to the identification of 22 new RL quasars out of a total of 48 candidates observed. The last SDSS quasar catalogue (V), based on SDSS DR7 (Schneider et al. 2010), lists 73 QSO matching our selection criteria. Fifteen of our new high-redshift QSOs are still missing in this catalogue. Therefore, in addition to a good efficiency, our technique leads to a very high completeness ( 97%) compared to that of SDSS. This allows to determine the most accurate luminosity function up to date for RLQ in this range of high redshift.

  14. Activities Selected from the High School Geography Project.

    ERIC Educational Resources Information Center

    Natoli, Salvatore J., Ed.; And Others

    Out of approximately 50 activities which were, for a variety of reasons, not included in the final version of the High School Geography Project course, Geography in an Urban Age, the HSGP staff selected eight which would be useful in many secondary school classrooms. The activities included here are: 1) Operation Bigger Beef (on themes of cultural…

  15. High selectivity ZIF-93 hollow fiber membranes for gas separation.

    PubMed

    Cacho-Bailo, Fernando; Caro, Guillermo; Etxeberría-Benavides, Miren; Karvan, Oğuz; Téllez, Carlos; Coronas, Joaquín

    2015-06-30

    Zeolitic imidazolate framework-93 (ZIF-93) continuous membranes were synthesized on the inner side of P84 co-polyimide hollow fiber supports by microfluidics. MOFs and polymers showed high compatibility and the membrane exhibited H2-CH4 and CO2-CH4 separation selectivities of 97 (100 °C) and 17 (35 °C), respectively.

  16. Highly selective oligosaccharide sensing by a Curdlan-polythiophene hybrid.

    PubMed

    Fukuhara, Gaku; Inoue, Yoshihisa

    2011-02-02

    An in situ hybrid complex of Curdlan with water-soluble polythiophene functioned as a highly sensitive and selective saccharide chemosensor in aqueous media, enabling us to discriminate tetrasaccharide acarbose at 1 μM from 24 mono-, di-, tri-, tetra-, and pentasaccharides.

  17. Brief Report: Conveying Subjective Experience in Conversation: Production of Mental State Terms and Personal Narratives in Individuals with High Functioning Autism

    ERIC Educational Resources Information Center

    Bang, Janet; Burns, Jesse; Nadig, Aparna

    2013-01-01

    Mental state terms and personal narratives are conversational devices used to communicate subjective experience in conversation. Pre-adolescents with high-functioning autism (HFA, n = 20) were compared with language-matched typically-developing peers (TYP, n = 17) on production of mental state terms (i.e., perception, physiology, desire, emotion,…

  18. High-Efficiency Nonfullerene Polymer Solar Cell Enabling by Integration of Film-Morphology Optimization, Donor Selection, and Interfacial Engineering.

    PubMed

    Zhang, Xin; Li, Weiping; Yao, Jiannian; Zhan, Chuanlang

    2016-06-22

    Carrier mobility is a vital factor determining the electrical performance of organic solar cells. In this paper we report that a high-efficiency nonfullerene organic solar cell (NF-OSC) with a power conversion efficiency of 6.94 ± 0.27% was obtained by optimizing the hole and electron transportations via following judicious selection of polymer donor and engineering of film-morphology and cathode interlayers: (1) a combination of solvent annealing and solvent vapor annealing optimizes the film morphology and hence both hole and electron mobilities, leading to a trade-off of fill factor and short-circuit current density (Jsc); (2) the judicious selection of polymer donor affords a higher hole and electron mobility, giving a higher Jsc; and (3) engineering the cathode interlayer affords a higher electron mobility, which leads to a significant increase in electrical current generation and ultimately the power conversion efficiency (PCE).

  19. Early traumatic experiences, perceived discrimination and conversion to psychosis in those at clinical high risk for psychosis.

    PubMed

    Stowkowy, Jacqueline; Liu, Lu; Cadenhead, Kristin S; Cannon, Tyrone D; Cornblatt, Barbara A; McGlashan, Thomas H; Perkins, Diana O; Seidman, Larry J; Tsuang, Ming T; Walker, Elaine F; Woods, Scott W; Bearden, Carrie E; Mathalon, Daniel H; Addington, Jean

    2016-04-01

    There is evidence to suggest that both early traumatic experiences and perceived discrimination are associated with later onset of psychosis. Less is known about the impact these two factors may have on conversion to psychosis in those who are at clinical high risk (CHR) of developing psychosis. The purpose of this study was to determine if trauma and perceived discrimination were predictors of conversion to psychosis. The sample consisted of 764 individuals who were at CHR of developing psychosis and 280 healthy controls. All participants were assessed on past trauma, bullying and perceived discrimination. Individuals at CHR reported significantly more trauma, bullying and perceived discrimination than healthy controls. Only perceived discrimination was a predictor of later conversion to psychosis. Given that CHR individuals are reporting increased rates of trauma and perceived discrimination, these should be routinely assessed, with the possibility of offering interventions aimed at ameliorating the impact of past traumas as well as improving self-esteem and coping strategies in an attempt to reduce perceived discrimination.

  20. Origins of Large Voltage Hysteresis in High-Energy-Density Metal Fluoride Lithium-Ion Battery Conversion Electrodes.

    PubMed

    Li, Linsen; Jacobs, Ryan; Gao, Peng; Gan, Liyang; Wang, Feng; Morgan, Dane; Jin, Song

    2016-03-02

    Metal fluorides and oxides can store multiple lithium ions through conversion chemistry to enable high-energy-density lithium-ion batteries. However, their practical applications have been hindered by an unusually large voltage hysteresis between charge and discharge voltage profiles and the consequent low-energy efficiency (<80%). The physical origins of such hysteresis are rarely studied and poorly understood. Here we employ in situ X-ray absorption spectroscopy, transmission electron microscopy, density functional theory calculations, and galvanostatic intermittent titration technique to first correlate the voltage profile of iron fluoride (FeF3), a representative conversion electrode material, with evolution and spatial distribution of intermediate phases in the electrode. The results reveal that, contrary to conventional belief, the phase evolution in the electrode is symmetrical during discharge and charge. However, the spatial evolution of the electrochemically active phases, which is controlled by reaction kinetics, is different. We further propose that the voltage hysteresis in the FeF3 electrode is kinetic in nature. It is the result of ohmic voltage drop, reaction overpotential, and different spatial distributions of electrochemically active phases (i.e., compositional inhomogeneity). Therefore, the large hysteresis can be expected to be mitigated by rational design and optimization of material microstructure and electrode architecture to improve the energy efficiency of lithium-ion batteries based on conversion chemistry.

  1. Enhanced energy conversion efficiency from high strength synthetic organic wastewater by sequential dark fermentative hydrogen production and algal lipid accumulation.

    PubMed

    Ren, Hong-Yu; Liu, Bing-Feng; Kong, Fanying; Zhao, Lei; Xing, Defeng; Ren, Nan-Qi

    2014-04-01

    A two-stage process of sequential dark fermentative hydrogen production and microalgal cultivation was applied to enhance the energy conversion efficiency from high strength synthetic organic wastewater. Ethanol fermentation bacterium Ethanoligenens harbinense B49 was used as hydrogen producer, and the energy conversion efficiency and chemical oxygen demand (COD) removal efficiency reached 18.6% and 28.3% in dark fermentation. Acetate was the main soluble product in dark fermentative effluent, which was further utilized by microalga Scenedesmus sp. R-16. The final algal biomass concentration reached 1.98gL(-1), and the algal biomass was rich in lipid (40.9%) and low in protein (23.3%) and carbohydrate (11.9%). Compared with single dark fermentation stage, the energy conversion efficiency and COD removal efficiency of two-stage system remarkably increased 101% and 131%, respectively. This research provides a new approach for efficient energy production and wastewater treatment using a two-stage process combining dark fermentation and algal cultivation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. High opportunity for postcopulatory sexual selection under field conditions.

    PubMed

    Turnell, Biz R; Shaw, Kerry L

    2015-08-01

    In polygamous systems, male fitness is determined not only by mating success but also by fertilization success. Despite the growing interest over the past several decades in postcopulatory sexual selection, its relative importance compared to precopulatory sexual selection remains a subject of debate. Here, we use extensive behavioral observations of a seminatural population of Hawaiian swordtail crickets, Laupala cerasina, and molecular paternity assignment to measure the opportunities for pre- and postcopulatory selection. Because postcopulatory selection has the potential to operate at multiple stages, we also separately attribute its effects to factors specific to mating events versus factors specific to males. We find that variance in postcopulatory success is over four times as great as variance in precopulatory success, with most of it unexplained by male mating order or the number of nuptial gifts given. Surprisingly, we also find that male singing effort is under postcopulatory selection, suggesting that males who sing more frequently also have more competitive ejaculates. Our results are consistent with the hypothesis that high polyandry levels promote greater relative postcopulatory selection. They also highlight the need for detailed behavioral observations under conditions as natural as possible when measuring mating and reproductive success.

  3. Evaluation of a microwave high-power reception-conversion array for wireless power transmission

    NASA Technical Reports Server (NTRS)

    Dickinson, R. M.

    1975-01-01

    Initial performance tests of a 24-sq m area array of rectenna elements are presented. The array is used as the receiving portion of a wireless microwave power transmission engineering verification test system. The transmitting antenna was located at a range of 1.54 km. Output dc voltage and power, input RF power, efficiency, and operating temperatures were obtained for a variety of dc load and RF incident power levels at 2388 MHz. Incident peak RF intensities of up to 170 mW/sq cm yielded up to 30.4 kW of dc output power. The highest derived collection-conversion efficiency of the array was greater than 80 percent.

  4. Energy Conversion Mechanism for Electron Perpendicular Energy in High Guide-Field Reconnection

    NASA Astrophysics Data System (ADS)

    Guo, Xuehan; Horiuchi, Ritoku; Kaminou, Yasuhiro; Cheng, Frank; Ono, Yasushi

    2016-10-01

    The energy conversion mechanism for electron perpendicular energy, both the thermal and the kinetic energy, is investigated by means of two-dimensional, full-particle simulations in an open system. It is shown that electron perpendicular heating is mainly due to the breaking of magnetic moment conservation in separatrix region because the charge separation generates intense variation of electric field within the electron Larmor radius. Meanwhile, electron perpendicular acceleration takes place manly due to the polarization drift term as well as the curvature drift term of E . u⊥ in the downstream near the X-point. The enhanced electric field due to the charge separation there results in a significant effect of the polarization drift term on the dissipation of magnetic energy within the ion inertia length in the downstream. Japan Society for the Promotion of Science (JSPS) Fellows 15J03758.

  5. Conversion of forest residues to a methane-rich gas in a high-throughput gasifier

    NASA Astrophysics Data System (ADS)

    Feldman, H. F.; Paisley, M. A.; Folsom, D. W.; Kim, B. C.

    1981-10-01

    Results of the experimental work conducted thus far show that wood can be readily gasified in a steam environment into a hydrocarbon rich fuel gas that can be used as a replacement for petroleum based fuels or natural gas with minimal boiler retrofit. Further, this conversion can be achieved in a compact gasification reactor with heat supplied by a circulating entrained phase, thereby eliminating the need for an oxygen plant. Tars were found except at the lowest gasifier temperatures employed, and therefore heat recovery from the product gas should be much simpler than that from commercially available fixed bed gasification systems where product gas contains significant quantities of tar. The data generated were used in a preliminary conceptual design. Evaluation of this design shows that a medium Btu gas can be produced from wood at a cost competitive with natural gas or petroleum based fuels.

  6. Photon spectrum and polarization for high conversion coefficient in the Compton backscattering process

    NASA Astrophysics Data System (ADS)

    Potylitsyn, A. P.; Kolchuzhkin, A. M.; Strikhanov, M. N.; Strokov, S. A.

    2017-07-01

    This study looks to simulate the nonlinear Compton backscattering (CBS) process based on the Monte Carlo technique for the conversion coefficient Kc ⩾ 1 , which can be considered as the average number of photons emitted by each electron. The characteristics of the nonlinear CBS process simulated in this work are as follows: the number of absorbed photons of a laser, the distance in the laser pulse in which the electron passes between two collisions, the energy and the polarization of the emitted photon in each collision, and the polarization of the electron before and after collision. The developed approach allows us to find the spectra and polarization characteristics of the final electrons and photons. When Kc > 1 , the spin-flip processes need to be considered for a correct simulation of the polarization of the final photons and electrons for energies typical of a γ- γ collider.

  7. High efficiency β radioisotope energy conversion using reciprocating electromechanical converters with integrated betavoltaics

    NASA Astrophysics Data System (ADS)

    Duggirala, Rajesh; Li, Hui; Lal, Amit

    2008-04-01

    We demonstrate a 5.1% energy conversion efficiency Ni63 radioisotope power generator by integrating silicon betavoltaic converters with radioisotope actuated reciprocating piezoelectric unimorph cantilever converters. The electromechanical energy converter efficiently utilizes both the kinetic energy and the electrical charge of the 0.94μW β radiation from a 9mCi Ni63 thin film source to generate maximum (1) continuous betavoltaic electrical power output of 22nW and (2) pulsed piezoelectric electrical power output of 750μW at 0.07% duty cycle. The electromechanical converters can be potentially used to realize 100year lifetime power sources for powering periodic sampling remote wireless sensor microsystems.

  8. Conversion and Blending Facility highly enriched uranium to low enriched uranium as oxide. Revision 1

    SciTech Connect

    1995-07-05

    This Conversion and Blending Facility (CBF) will have two missions: (1) convert HEU materials into pure HEU oxide and (2) blend the pure HEU oxide with depleted and natural uranium oxide to produce an LWR grade LEU product. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. To the extent practical, the chemical and isotopic concentrations of blended LEU product will be held within the specifications required for LWR fuel. Such blended LEU product will be offered to the United States Enrichment Corporation (USEC) to be sold as feed material to the commercial nuclear industry. Otherwise, blended LEU will be produced as a waste suitable for storage or disposal.

  9. Producing high fidelity single photons with optimal brightness via waveguided parametric down-conversion.

    PubMed

    Laiho, K; Cassemiro, K N; Silberhorn, Ch

    2009-12-07

    Parametric down-conversion (PDC) offers the possibility to control the fabrication of non-Gaussian states such as Fock states. However, in conventional PDC sources energy and momentum conservation introduce strict frequency and photon number correlations, which impact the fidelity of the prepared state. In our work we optimize the preparation of single-photon Fock states from the emission of waveguided PDC via spectral filtering. We study the effect of correlations via photon number resolving detection and quantum interference. Our measurements show how the reduction of mixedness due to filtering can be evaluated. Interfering the prepared photon with a coherent state we establish an experimentally measured fidelity of the produced target state of 78%.

  10. Conversion and Blending Facility Highly enriched uranium to low enriched uranium as uranium hexafluoride. Revision 1

    SciTech Connect

    1995-07-05

    This report describes the Conversion and Blending Facility (CBF) which will have two missions: (1) convert surplus HEU materials to pure HEU UF{sub 6} and a (2) blend the pure HEU UF{sub 6} with diluent UF{sub 6} to produce LWR grade LEU-UF{sub 6}. The primary emphasis of this blending be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. The chemical and isotopic concentrations of the blended LEU product will be held within the specifications required for LWR fuel. The blended LEU product will be offered to the United States Enrichment Corporation (USEC) to be sold as feed material to the commercial nuclear industry.

  11. Energy conversion mechanism for electron perpendicular energy in high guide-field reconnection

    NASA Astrophysics Data System (ADS)

    Guo, X.; Horiuchi, R.; Cheng, C. Z.; Kaminou, Y.; Ono, Y.

    2017-03-01

    The energy conversion mechanism for electron perpendicular energy, both the thermal and the kinetic energies, is investigated by means of two-dimensional, full-particle simulations in an open system. It is shown that electron perpendicular heating is mainly due to the breaking of magnetic moment conservation in separatrix region because the charge separation generates intense variation of electric field within the several electron Larmor radii. Meanwhile, electron perpendicular acceleration takes place mainly due to the polarization drift term as well as the curvature drift term of E .u⊥ in the downstream near the X-point. The enhanced electric field due to the charge separation there results in a significant effect of the polarization drift term on the dissipation of magnetic energy within the ion inertia length in the downstream.

  12. Construction of 3-Fold-Interpenetrated Three-Dimensional Metal-Organic Frameworks of Nickel(II) for Highly Efficient Capture and Conversion of Carbon Dioxide.

    PubMed

    Ugale, Bharat; Dhankhar, Sandeep Singh; Nagaraja, C M

    2016-10-03

    A series of three new isostructural metal-organic frameworks (MOFs) of nickel(II), [{Ni(muco)(bpa)(2H2O)}·2H2O] (1), [{Ni(muco)(bpe)(2H2O)}·2.5H2O] (2), and [{Ni(muco)(azopy)(2H2O)}·2H2O] (3) [where muco = trans,trans-muconate dianion, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethylene, and azopy = 4,4'-bis(azobipyridine)], have been synthesized and characterized by single-crystal X-ray diffraction analysis and other physicochemical methods. Compounds 1-3 exhibit an interesting 3-fold-interpenetrated three-dimensional pillar-layered framework structure constituted of 4-coordinating (4-c) Ni(II) nodes with {6(6)}-neb net topology. Remarkably, in spite of 3-fold interpenetration, the structures possess one-dimensional channels with dimensions of ∼8.05 × 5.25 Å(2). Gas (N2, Ar, H2, and CO2) adsorption studies of compounds 2 and 3 revealed selective adsorption properties for CO2 over other gases. In all three structures, the 4-c Ni(II) node has two coordinated H2O molecules that can be reversibly removed by high-temperature treatment to generate a dehydrated framework composed of highly unsaturated, Lewis acidic Ni(II) ions. Further, the activated compounds of 1-3 act as efficient recyclable catalysts for heterogeneous cycloaddition of CO2 with styrene oxide, resulting in cyclic carbonate with high conversion and selectivity. Interestingly, the cycloaddition reactions of CO2 with bulky epoxides show a decrease in the activity with an increase in the alkyl chain length of the substrate due to confinement of the pore size of the MOF. The high catalytic efficiency and size-dependent selectivity for smaller epoxides show the potential utility of 1 as a promising heterogeneous catalyst for the cycloaddition of CO2. Furthermore, the catalyst can be easily separated and reused for several cycles without significant reduction in the catalytic activity as well as structural rigidity. Compounds 1-3 represent rare examples of interpenetrated MOFs exhibiting

  13. Selected organ dose conversion coefficients for external photons calculated using ICRP adult voxel phantoms and Monte Carlo code FLUKA.

    PubMed

    Patni, H K; Nadar, M Y; Akar, D K; Bhati, S; Sarkar, P K

    2011-11-01

    The adult reference male and female computational voxel phantoms recommended by ICRP are adapted into the Monte Carlo transport code FLUKA. The FLUKA code is then utilised for computation of dose conversion coefficients (DCCs) expressed in absorbed dose per air kerma free-in-air for colon, lungs, stomach wall, breast, gonads, urinary bladder, oesophagus, liver and thyroid due to a broad parallel beam of mono-energetic photons impinging in anterior-posterior and posterior-anterior directions in the energy range of 15 keV-10 MeV. The computed DCCs of colon, lungs, stomach wall and breast are found to be in good agreement with the results published in ICRP publication 110. The present work thus validates the use of FLUKA code in computation of organ DCCs for photons using ICRP adult voxel phantoms. Further, the DCCs for gonads, urinary bladder, oesophagus, liver and thyroid are evaluated and compared with results published in ICRP 74 in the above-mentioned energy range and geometries. Significant differences in DCCs are observed for breast, testis and thyroid above 1 MeV, and for most of the organs at energies below 60 keV in comparison with the results published in ICRP 74. The DCCs of female voxel phantom were found to be higher in comparison with male phantom for almost all organs in both the geometries.

  14. Highly Selective Separation of DNA Fragments Using Optically Directed Transport

    SciTech Connect

    Braiman, Avital; Rudakov, Fedor M; Thundat, Thomas George

    2010-01-01

    We present a design that allows selective separation of biomolecules of a particular size without performing complete separation of the sample by size. By focusing a laser beam onto a photoelectrode in contact with an electrolyte medium, a highly localized and optically controlled photoelectrophoretic trap is created. Moving the light beam along the photoelectrode consequently moves the trap. We demonstrate that by manipulating the speed of the photoelectrophoretic trap biomolecules of a particular size can be selectively separated from the mixture. We achieve a qualitative agreement between our experimental results and numerical simulations.

  15. Effects of surface diffusion on high temperature selective emitters

    DOE PAGES

    Peykov, Daniel; Yeng, Yi Xiang; Celanovic, Ivan; ...

    2015-01-01

    Using morphological and optical simulations of 1D tantalum photonic crystals at 1200K, surface diffusion was determined to gradually reduce the efficiency of selective emitters. This was attributed to shifting resonance peaks and declining emissivity caused by changes to the cavity dimensions and the aperture width. Decreasing the structure’s curvature through larger periods and smaller cavity widths, as well as generating smoother transitions in curvature through the introduction of rounded cavities, was found to alleviate this degradation. An optimized structure, that shows both high efficiency selective emissivity and resistance to surface diffusion, was presented.

  16. Highly active and selective endopeptidases with programmed substrate specificities

    PubMed Central

    Varadarajan, Navin; Rodriguez, Sarah; Hwang, Bum-Yeol; Georgiou, George; Iverson, Brent L

    2009-01-01

    A family of engineered endopeptidases has been created that is capable of cleaving a diverse array of peptide sequences with high selectivity and catalytic efficiency (kcat/KM > 104 M−1 s−1). By screening libraries with a selection-counterselection substrate method, protease variants were programmed to recognize amino acids having altered charge, size and hydrophobicity properties adjacent to the scissile bond of the substrate, including Glu↓Arg, a specificity that to our knowledge has not been observed among natural proteases. Members of this artificial protease family resulted from a relatively small number of amino acid substitutions that (at least in one case) proved to be epistatic. PMID:18391948

  17. Development and Testing of High-Temperature Solar Selective Coatings

    SciTech Connect

    Kennedy, C.; Price, H.

    2005-01-01

    The Solar Energy Technologies Program is working to reduce the cost of parabolic trough solar power technology. System studies show that increasing the operating temperature of the solar field from 390 to >450 C will result in improved performance and cost reductions. This requires the development of new more-efficient selective coatings that have both high solar absorptance (>0.96) and low thermal emittance (<0.07) and are thermally stable above 450 C, ideally in air. Potential selective coatings were modeled, identified for laboratory prototyping, and manufactured at NREL. Optimization of the samples and high-temperature durability testing will be performed. Development of spectrally selective materials depends on reliable characterization of their optical properties. Protocols for testing the thermal/optical properties of selective coatings were developed and a round-robin experiment was conducted to verify and document the reflectance and high-temperature emittance measurements. The development, performance, and durability of these materials and future work will be described.

  18. High-Efficiency Selective Electron Tunnelling in a Heterostructure Photovoltaic Diode.

    PubMed

    Jia, Chuancheng; Ma, Wei; Gu, Chunhui; Chen, Hongliang; Yu, Haomiao; Li, Xinxi; Zhang, Fan; Gu, Lin; Xia, Andong; Hou, Xiaoyuan; Meng, Sheng; Guo, Xuefeng

    2016-06-08

    A heterostructure photovoltaic diode featuring an all-solid-state TiO2/graphene/dye ternary interface with high-efficiency photogenerated charge separation/transport is described here. Light absorption is accomplished by dye molecules deposited on the outside surface of graphene as photoreceptors to produce photoexcited electron-hole pairs. Unlike conventional photovoltaic conversion, in this heterostructure both photoexcited electrons and holes tunnel along the same direction into graphene, but only electrons display efficient ballistic transport toward the TiO2 transport layer, thus leading to effective photon-to-electricity conversion. On the basis of this ipsilateral selective electron tunnelling (ISET) mechanism, a model monolayer photovoltaic device (PVD) possessing a TiO2/graphene/acridine orange ternary interface showed ∼86.8% interfacial separation/collection efficiency, which guaranteed an ultrahigh absorbed photon-to-current efficiency (APCE, ∼80%). Such an ISET-based PVD may become a fundamental device architecture for photovoltaic solar cells, photoelectric detectors, and other novel optoelectronic applications with obvious advantages, such as high efficiency, easy fabrication, scalability, and universal availability of cost-effective materials.

  19. ULTRASENSITIVE HIGH-TEMPERATURE SELECTIVE GAS DETECTION USING PIEZOELECTRIC MICROCANTILEVERS

    SciTech Connect

    Wan Y. Shih; Tejas Patil; Qiang Zhao; Yi-Shi Chiu; Wei-Heng Shih

    2004-03-05

    We have obtained very promising results in the Phase I study. Specifically, for temperature effects, we have established that piezoelectric cantilever sensors could retain their resonance peak strength at high temperatures, i.e., the Q values of the resonance peaks remained above 10 even when the temperature was very close to the Curie temperature. This confirms that a piezoelectric cantilever sensor can be used as a sensor up to its Curie temperature. Furthermore, we have shown that the mass detection sensitivity remained unchanged at different temperatures. For selective gas detection, we have demonstrated selective NH{sub 3} detection using piezoelectric cantilever sensors coated with mesoporous SiO{sub 2}. For high-temperature sensor materials development, we have achieved highly oriented Sr-doped lead titanate thin films that possessed superior dielectric and ferroelectric properties. Such highly oriented films can be microfabricated into high-performance piezoelectric microcantilever sensors that can be used up to 490 C. We have accomplished the goal of Phase I study in exploring the various aspects of a high-temperature gas sensor. We propose to continue the study in Phase II to develop a sensor that is suitable for high-temperature applications using piezoelectrics with a high Curie temperature and by controlling the effects of temperature. The lead titanate based thin film developed in Phase I is good for applications up to 490 C. In phase II, we will develop lithium niobate thin film based cantilevers for applications up to 1000 C.

  20. Conversion of Low-Flow Priapism to High-Flow State Using T-Shunt with Tunneling

    PubMed Central

    Tadros, Nicholas N.; Hedges, Jason C.

    2017-01-01

    Introduction. The three types of priapism are stuttering, arterial (high-flow, nonischemic), and venoocclusive (low-flow, ischemic). These are usually distinct entities and rarely occur in the same patient. T-shunts and other distal shunts are frequently combined with tunneling, but a seldom recognized potential complication is conversion to a high-flow state. Case Presentation. We describe 2 cases of men who presented with low-flow priapism episodes that were treated using T-shunts with tunneling that resulted with both men having recurrent erections shortly after surgery that were found to be consistent with high-flow states. Case 1 was a 33-year-old male with sickle cell anemia and case 2 was a 24-year-old male with idiopathic thrombocytopenic purpura. In both cases the men were observed over several weeks and both men returned to normal erectile function. Conclusions. Historically, proximal shunts were performed only in cases when distal shunts failed and carry a higher risk of serious complications. T-shunts and other distal shunts combined with tunneling are being used more frequently in place of proximal shunts. These cases illustrate how postoperative erections after T-shunts with tunneling can signify a conversion from low-flow to high-flow states and could potentially be misdiagnosed as an operative failure. PMID:28331646

  1. Non-native Co-, Mn-, and Ti-oxyhydroxide nanocrystals in ferritin for high efficiency solar energy conversion.

    PubMed

    Erickson, S D; Smith, T J; Moses, L M; Watt, R K; Colton, J S

    2015-01-09

    Quantum dot solar cells seek to surpass the solar energy conversion efficiencies achieved by bulk semiconductors. This new field requires a broad selection of materials to achieve its full potential. The 12 nm spherical protein ferritin can be used as a template for uniform and controlled nanocrystal growth, and to then house the nanocrystals for use in solar energy conversion. In this study, precise band gaps of titanium, cobalt, and manganese oxyhydroxide nanocrystals within ferritin were measured, and a change in band gap due to quantum confinement effects was observed. The range of band gaps obtainable from these three types of nanocrystals is 2.19-2.29 eV, 1.93-2.15 eV, and 1.60-1.65 eV respectively. From these measured band gaps, theoretical efficiency limits for a multi-junction solar cell using these ferritin-enclosed nanocrystals are calculated and found to be 38.0% for unconcentrated sunlight and 44.9% for maximally concentrated sunlight. If a ferritin-based nanocrystal with a band gap similar to silicon can be found (i.e. 1.12 eV), the theoretical efficiency limits are raised to 51.3% and 63.1%, respectively. For a current matched cell, these latter efficiencies become 41.6% (with an operating voltage of 5.49 V), and 50.0% (with an operating voltage of 6.59 V), for unconcentrated and maximally concentrated sunlight respectively.

  2. Highly Z-Selective Metathesis Homocoupling of Terminal Olefins

    PubMed Central

    Jiang, Annie J.; Zhao, Yu; Schrock, Richard R.; Hoveyda, Amir H.

    2009-01-01

    Mo and W MonoAryloxide-Pyrrolide (MAP) olefin metathesis catalysts can couple terminal olefins to give as high as >98% Z-products in moderate to high yields with as little as 0.2% catalyst. Results are reported for 1-hexene, 1-octene, allylbenzene, allyltrimethylsilane, methyl-10-undecenoate, methyl-9-decenoate, allylB(pinacolate), allylOBenzyl, allylNHTosyl, and allylNHPh. It is proposed that high Z-selectivity is achieved because a large aryloxide only allows metallacyclobutanes to form that contain adjacent cis substituents and because isomerization of Z-product to E-product can be slow in that same steric environment. PMID:19919135

  3. Highly Efficient Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over Gold Supported on Zinc Oxide Materials

    SciTech Connect

    Chen, Hangning; Cullen, David A.; Larese, J. Z.

    2015-11-30

    We used Au/ZnO catalysts for liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol and compared with Au/Fe2O3 catalysts. To investigate the influence of the support on the hydrogenation activity and selectivity, three different Au/ZnO catalysts were synthesized, including Au/rod-tetrapod ZnO, Au/porous ZnO, and Au/ZnO-CP prepared using a coprecipitation method. Moreover, the influence of calcination temperature was also systematically investigated in this study. The characterization of Au/ZnO catalysts was performed using ICP, N2 adsorption/desorption isotherms, X-ray diffraction, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy. Among all the supported Au catalysts prepared in this study, Au/ZnO-CP exhibits both the highest hydrogenation activity and selectivity. Using a 1.5% Au/ZnO-CP catalyst, 100% selectivity could be achieved with 94.9% conversion. Finally, we find that the Au particle (size and shape), the ZnO support (size and surface texture) and the interaction between Au and ZnO are three important parameters for achieving a highly efficient Au/ZnO catalyst.

  4. Highly Efficient Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over Gold Supported on Zinc Oxide Materials

    DOE PAGES

    Chen, Hangning; Cullen, David A.; Larese, J. Z.

    2015-11-30

    We used Au/ZnO catalysts for liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol and compared with Au/Fe2O3 catalysts. To investigate the influence of the support on the hydrogenation activity and selectivity, three different Au/ZnO catalysts were synthesized, including Au/rod-tetrapod ZnO, Au/porous ZnO, and Au/ZnO-CP prepared using a coprecipitation method. Moreover, the influence of calcination temperature was also systematically investigated in this study. The characterization of Au/ZnO catalysts was performed using ICP, N2 adsorption/desorption isotherms, X-ray diffraction, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy. Among all the supported Au catalysts prepared in this study, Au/ZnO-CP exhibits both the highest hydrogenationmore » activity and selectivity. Using a 1.5% Au/ZnO-CP catalyst, 100% selectivity could be achieved with 94.9% conversion. Finally, we find that the Au particle (size and shape), the ZnO support (size and surface texture) and the interaction between Au and ZnO are three important parameters for achieving a highly efficient Au/ZnO catalyst.« less

  5. Unraveling the role of support surface hydroxyls and its effect on the selectivity of C2 species over Rh/γ-Al2O3 catalyst in syngas conversion: A theoretical study

    NASA Astrophysics Data System (ADS)

    Zhang, Riguang; Duan, Tian; Wang, Baojun; Ling, Lixia

    2016-08-01

    The supported Rh-based catalysts exhibit the excellent catalytic performances for syngas conversion to C2 species. In this study, all possible elementary steps leading to C2 species from syngas have been explored to identify the role of support and its surface hydroxyls over Rh/γ-Al2O3 catalyst; Here, the results are obtained using density functional theory (DFT) method. Two models: Rh4 cluster supported on the dry γ-Al2O3(110) surface, D(Rh4), and on the hydroxylated γ-Al2O3(110) surface, H(Rh4), have been used to model Rh/γ-Al2O3 catalyst. Our results show that CO prefers to be hydrogenated to CHO, subsequently, starting from CHO species, CH and CH2 species are the dominate monomers among CHx(x = 1-3) species rather than CH3 and CH3OH on D(Rh4) and H(Rh4) surfaces, suggesting that γ-Al2O3-supported Rh catalyst exhibits the high selectivity towards CHx formation compared to the pure Rh catalyst. On the other hand, D(Rh4) is more favorable for C2 hydrocarbon (C2H2) formation, whereas H(Rh4) surface easily produces C2 hydrocarbon (C2H2) and C2 oxygenates (CHCO,CH2CHO), indicating that the surface hydroxyls of support can affect the selectivity of C2 species over Rh/γ-Al2O3 catalyst in syngas conversion. Moreover, compared to the pure Rh(111) surface, Rh/γ-Al2O3 catalyst can achieve the excellent catalytic performances for syngas conversion to C2 species.

  6. Design definition of a microwave power reception and conversion system for use on a high altitude powered platform

    NASA Technical Reports Server (NTRS)

    Brown, W. C.

    1981-01-01

    The design definition of a microwave power reception and conversion system for use on high altitude powered platform is presented. The study includes an initial design, construction and test effort on a thin film, printed circuit rectenna. A study of a low altitude demonstration of an airborne rectenna was made starting with the assumption that a fifty foot mechanically steerable parabolic reflector at the Wallops Flight Center would be retrofitted with a low microwave power source consisting of a five kilowatt commercially available magnetron and that a small blimp would be used to support the rectenna.

  7. Active High Power Conversion Efficiency Rectifier With Built-In Dual-Mode Back Telemetry in Standard CMOS Technology.

    PubMed

    Bawa, G; Ghovanloo, M

    2008-09-01

    In this paper, we present an active rectifier with high power conversion efficiency (PCE) implemented in a 0.5- mum 5 V standard CMOS technology with two modes of built-in back telemetry; short- and open-circuit. As a rectifier, it ensures a PCE > 80%, taking advantage of active synchronous rectification technique in the frequency range of 0.125-1 MHz. The built-in complementary back telemetry feature can be utilized in implantable microelectronic devices (IMD), wireless sensors, and radio frequency identification (RFID) applications to reduce the silicon area, increase the data rate, and improve the reading range and robustness in load shift keying (LSK).

  8. Variability selected high-redshift quasars on SDSS Stripe 82

    NASA Astrophysics Data System (ADS)

    Palanque-Delabrouille, N.; Yeche, Ch.; Myers, A. D.; Petitjean, P.; Ross, N. P.; Sheldon, E.; Aubourg, E.; Delubac, T.; Le Goff, J.-M.; Pâris, I.; Rich, J.; Dawson, K. S.; Schneider, D. P.; Weaver, B. A.

    2011-06-01

    The SDSS-III BOSS Quasar survey will attempt to observe z > 2.15 quasars at a density of at least 15 per square degree to yield the first measurement of the baryon acoustic oscillations in the Ly-α forest. To help reaching this goal, we have developed a method to identify quasars based on their variability in the ugriz optical bands. The method has been applied to the selection of quasar targets in the SDSS region known as Stripe 82 (the southern equatorial stripe), where numerous photometric observations are available over a 10-year baseline. This area was observed by BOSS during September and October 2010. Only 8% of the objects selected via variability are not quasars, while 90% of the previously identified high-redshift quasar population is recovered. The method allows for a significant increase in the z > 2.15 quasar density over previous strategies based on optical (ugriz) colors, achieving a density of 24.0 deg-2 on average down to g ~ 22 over the 220 deg2 area of Stripe 82. We applied this method to simulated data from the Palomar Transient Factory and from Pan-STARRS, and showed that even with data that have sparser time sampling than what is available in Stripe 82, including variability in future quasar selection strategies would lead to increased target selection efficiency in the z > 2.15 redshift range. We also found that broad absorption line quasars are preferentially present in a variability than in a color selection.

  9. Cyclic cholecystokinin analogues with high selectivity for central receptors.

    PubMed Central

    Charpentier, B; Pelaprat, D; Durieux, C; Dor, A; Reibaud, M; Blanchard, J C; Roques, B P

    1988-01-01

    Taking as a model the N-terminal folding of the cholecystokinin tyrosine-sulfated octapeptide [CCK-8; Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2] deduced from conformational studies, two cyclic cholecystokinin (CCK) analogues were synthesized by conventional peptide synthesis: Boc-D-Asp-Tyr(SO3H)-Ahx-D-Lys-Trp-Ahx-Asp-Phe-NH2 [compound I (Ahx, 2-aminohexanoic acid)] and Boc-gamma-D-Glu-Tyr(SO3H)-Ahx-D-Lys-Trp-Ahx-Asp-Phe-NH2 (compound II). The binding characteristics of these peptides were investigated on brain cortex membranes and pancreatic acini of guinea pig. Compounds I and II were competitive inhibitors of [3H]Boc[Ahx28,31]CCK-(27-33) binding to central CCK receptors and showed a high degree of selectivity for these binding sites (compound I: Ki for pancreas/Ki for brain, 179; compound II: Ki for pancreas/Ki for brain, 1979). This high selectivity was associated with a high affinity for central CCK receptors (compound I: Ki, 5.1 nM; compound II: Ki, 0.49 nM). Similar affinities and selectivities were found when 125I Bolton-Hunter-labeled CCK-8 was used as a ligand. Moreover, these compounds were only weakly active in the stimulation of amylase release from guinea pig pancreatic acini (EC50 greater than 10,000 nM) and were unable to induce contractions in the guinea pig ileum (to 10(-6) M). The two cyclic CCK analogues, therefore, appear to be synthetic ligands exhibiting both high affinity and high selectivity for central CCK binding sites. These compounds could help clarify the respective role of central and peripheral receptors for various CCK-8-induced pharmacological effects. PMID:3162318

  10. Superpermeable Atomic-Thin Graphene Membranes with High Selectivity.

    PubMed

    Wei, Gaoliang; Quan, Xie; Chen, Shuo; Yu, Hongtao

    2017-02-28

    Theoretical permeability of membrane is inversely proportional to its thickness, which indicates ultrathin membranes will be extremely permeable. Inspired by the atomic thickness of graphene, herein we report a four-layered graphene membrane with a thickness of about 2 nm. The ultrathin membrane is facilely fabricated by directly punching a complete graphene sheet through selective removal of some carbon atoms with metal oxide nanoparticles at high temperature. Their perpendicular pore channels spanning the whole thickness could, to a great extent, reduce hydrodynamic resistance for water transport. Experimental tests have revealed a flux of up to 4600 L m(-2) h(-1) of the membranes with a pore size of 50 nm and pore density of 1.0 × 10(7) cm(-2) at a pressure of 0.2 bar. This flux is 40-400 times higher than those of conventional ceramic membranes and track-etched membranes. The enhancement in water permeance is attributed to their atomic thickness and straight pore channels. High selectivity is also evidenced by selective separation of nanospheres with their narrowly distributed pores. These atomic-thin graphene membranes, in view of their outstanding permeability and selectivity, possess great potential as future advanced membranes and may inspire the design and development of other innovative membranes.

  11. Molecular Evolution of the CYP2D Subfamily in Primates: Purifying Selection on Substrate Recognition Sites without the Frequent or Long-Tract Gene Conversion

    PubMed Central

    Yasukochi, Yoshiki; Satta, Yoko

    2015-01-01

    The human cytochrome P450 (CYP) 2D6 gene is a member of the CYP2D gene subfamily, along with the CYP2D7P and CYP2D8P pseudogenes. Although the CYP2D6 enzyme has been studied extensively because of its clinical importance, the evolution of the CYP2D subfamily has not yet been fully understood. Therefore, the goal of this study was to reveal the evolutionary process of the human drug metabolic system. Here, we investigate molecular evolution of the CYP2D subfamily in primates by comparing 14 CYP2D sequences from humans to New World monkey genomes. Window analysis and statistical tests revealed that entire genomic sequences of paralogous genes were extensively homogenized by gene conversion during molecular evolution of CYP2D genes in primates. A neighbor-joining tree based on genomic sequences at the nonsubstrate recognition sites showed that CYP2D6 and CYP2D8 genes were clustered together due to gene conversion. In contrast, a phylogenetic tree using amino acid sequences at substrate recognition sites did not cluster the CYP2D6 and CYP2D8 genes, suggesting that the functional constraint on substrate specificity is one of the causes for purifying selection at the substrate recognition sites. Our results suggest that the CYP2D gene subfamily in primates has evolved to maintain the regioselectivity for a substrate hydroxylation activity between individual enzymes, even though extensive gene conversion has occurred across CYP2D coding sequences. PMID:25808902

  12. New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells.

    PubMed

    Wang, DongLin; Su, Gang

    2014-11-24

    Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350 nm-800 nm, the conversion efficiency of solar cells can be further enhanced.

  13. New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells

    PubMed Central

    Wang, DongLin; Su, Gang

    2014-01-01

    Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350 nm–800 nm, the conversion efficiency of solar cells can be further enhanced. PMID:25418477

  14. Direct conversion of surplus fissile materials, spent nuclear fuel, and other materials to high-level-waste glass

    SciTech Connect

    Forsberg, C.W.; Elam, K.R.

    1995-01-31

    With the end of the cold war the United States, Russia, and other countries have excess plutonium and other materials from the reductions in inventories of nuclear weapons. The United States Academy of Sciences (NAS) has recommended that these surplus fissile materials (SFMs) be processed so they are no more accessible than plutonium in spent nuclear fuel (SNF). This spent fuel standard, if adopted worldwide, would prevent rapid recovery of SFMs for the manufacture of nuclear weapons. The NAS recommended investigation of three sets of options for disposition of SFMs while meeting the spent fuel standard: (1) incorporate SFMs with highly radioactive materials and dispose of as waste, (2) partly burn the SFMs in reactors with conversion of the SFMs to SNF for disposal, and (3) dispose of the SFMs in deep boreholes. The US Government is investigating these options for SFM disposition. A new method for the disposition of SFMs is described herein: the simultaneous conversion of SFMs, SNF, and other highly radioactive materials into high-level-waste (HLW) glass. The SFMs include plutonium, neptinium, americium, and {sup 233}U. The primary SFM is plutonium. The preferred SNF is degraded SNF, which may require processing before it can be accepted by a geological repository for disposal.

  15. The origin of highly efficient selective emission in rare-earth oxides for thermophotovoltaic applications.

    PubMed

    Torsello, G; Lomascolo, M; Licciulli, A; Diso, D; Tundo, S; Mazzer, M

    2004-09-01

    Rare-earth oxide materials emit thermal radiation in a narrow spectral region, and can be used for a variety of different high-temperature applications, such as the generation of electricity by thermophotovoltaic conversion of thermal radiation. However, because a detailed understanding of the mechanism of selective emission from rare-earth atoms has so far been missing, attempts to engineer selective emitters have relied mainly on empirical approaches. In this work, we present a new quantum thermodynamic model to describe the mechanisms of thermal pumping and radiative de-excitation in rare-earth oxide materials. By evaluating the effects of the local crystal-field symmetry around a rare-earth ion, this model clearly explains how and why only some of the room-temperature absorption peaks give rise to highly efficient emission bands at high temperature (1,000-1,500 degrees C). High-temperature emissivity measurements along with photoluminescence and cathodoluminescence results confirm the predictions of the theory.

  16. Production of synthesis gas by partial oxidation and high-pressure shift conversion

    SciTech Connect

    Balz, D.F.; Gettert, H.F.; Gruendler, K.H.

    1983-01-01

    A fifteen-year history account of process improvements at the BASF ammonia plant at Ludwigshafen, West Germany is presented. Heavy fuel oil with a sulfur content of 1.75% (by weight) and with an ash content of about 0.015% (by weight) is used as feedstock at the plant. The fuel oil is converted with oxygen and steam to synthesis gas at a pressure of 80 bar. The synthesis gas generation is followed by raw-gas preheater, a two-step water-gas shift conversion, and a subsequent waste heat recovery. Sulfur compounds and CO/sub 4/ are removed from converted gas in a combination of a TEA- and an Alkazid-scrubber. Final purification and nitrogen enrichment is achieved in a liquid-nitrogen scrubber. The NH/sub 3/ synthesis operated at 350-430 bar, at which pressure NH/sub 3/-refrigeration of the recycle loop and purge gas removal are not necessary. (JMT)

  17. Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces

    NASA Astrophysics Data System (ADS)

    Lesne, E.; Fu, Yu; Oyarzun, S.; Rojas-Sánchez, J. C.; Vaz, D. C.; Naganuma, H.; Sicoli, G.; Attané, J.-P.; Jamet, M.; Jacquet, E.; George, J.-M.; Barthélémy, A.; Jaffrès, H.; Fert, A.; Bibes, M.; Vila, L.

    2016-12-01

    The spin-orbit interaction couples the electrons’ motion to their spin. As a result, a charge current running through a material with strong spin-orbit coupling generates a transverse spin current (spin Hall effect, SHE) and vice versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronic functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronic hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism--the Rashba effect--in the oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through spin pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES and highlight the importance of a long scattering time to achieve efficient spin-to-charge interconversion.

  18. Hydrothermal and wet disk milling pretreatment for high conversion of biosugars from oil palm mesocarp fiber.

    PubMed

    Zakaria, Mohd Rafein; Norrrahim, Mohd Nor Faiz; Hirata, Satoshi; Hassan, Mohd Ali

    2015-04-01

    Eco-friendly pretreatment methods for lignocellulosic biomass are being developed as alternatives to chemical based methods. Superheated steam (SHS), hot compressed water (HCW) and wet disk milling (WDM) were used individually and with combination to partially remove hemicellulose and alter the lignin composition of recalcitrant structure of oil palm mesocarp fiber (OPMF). The efficiency of the pretreatment methods was evaluated based on the chemical compositions altered, SEM analysis, power consumption and degree of enzymatic digestibility. Hemicellulose removal (94.8%) was more pronounced under HCW compared to SHS, due to maximal contact of water and production of acetic acid which enhanced further degradation of hemicellulose. Subsequent treatment with WDM resulted in defibrillation of OPMF and expansion of the specific surface area thus increasing the conversion of cellulose to glucose. The highest glucose yield was 98.1% (g/g-substrate) when pretreated with HCW (200 °C, 20 min) and WDM which only consumed 9.6 MJ/kg of OPMF. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Neutronics Conversion Analyses of the Laue-Langevin Institute (ILL) High Flux Reactor (RHF)

    SciTech Connect

    Bergeron, A.; Dionne, B.; Calzavara, Y.

    2014-09-30

    The following report describes the neutronics results obtained with the MCNP model of the RHF U7Mo LEU reference design that has been established in 2010 during the feasibility analysis. This work constitutes a complete and detailed neutronics analysis of that LEU design using models that have been significantly improved since 2010 and the release of the feasibility report. When possible, the credibility of the neutronics model is tested by comparing the HEU model results with experimental data or other codes calculations results. The results obtained with the LEU model are systematically compared to the HEU model. The changes applied to the neutronics model lead to better comparisons with experimental data or improved the calculation efficiency but do not challenge the conclusion of the feasibility analysis. If the U7Mo fuel is commercially available, not cost prohibitive, a back-end solution is established and if it is possible to manufacture the proposed element, neutronics analyses show that the performance of the reactor would not be challenged by the conversion to LEU fuel.

  20. High-rate solar photocatalytic conversion of CO2 and water vapor to hydrocarbon fuels.

    PubMed

    Varghese, Oomman K; Paulose, Maggie; Latempa, Thomas J; Grimes, Craig A

    2009-02-01

    Efficient solar conversion of carbon dioxide and water vapor to methane and other hydrocarbons is achieved using nitrogen-doped titania nanotube arrays, with a wall thickness low enough to facilitate effective carrier transfer to the adsorbing species, surface-loaded with nanodimensional islands of cocatalysts platinum and/or copper. All experiments are conducted in outdoor sunlight at University Park, PA. Intermediate reaction products, hydrogen and carbon monoxide, are also detected with their relative concentrations underlying hydrocarbon production rates and dependent upon the nature of the cocatalysts on the nanotube array surface. Using outdoor global AM 1.5 sunlight, 100 mW/cm(2), a hydrocarbon production rate of 111 ppm cm(-2) h(-1), or approximately 160 microL/(g h), is obtained when the nanotube array samples are loaded with both Cu and Pt nanoparticles. This rate of CO(2) to hydrocarbon production obtained under outdoor sunlight is at least 20 times higher than previous published reports, which were conducted under laboratory conditions using UV illumination.

  1. Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification

    PubMed Central

    Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

    2016-01-01

    Prions are formed of misfolded assemblies (PrPSc) of the variably N-glycosylated cellular prion protein (PrPC). In infected species, prions replicate by seeding the conversion and polymerization of host PrPC. Distinct prion strains can be recognized, exhibiting defined PrPSc biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrPSc assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrPC glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrPC species of interest as substrate. Applying the technique to PrPC glycosylation mutants expressing cells revealed that neither PrPC nor PrPSc glycoform stoichiometry was instrumental to PrPSc formation and strainness perpetuation. Our study supports the view that strain properties, including PrPSc glycotype are enciphered within PrPSc structural backbone, not in the attached glycans. PMID:27384922

  2. Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification.

    PubMed

    Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

    2016-07-07

    Prions are formed of misfolded assemblies (PrP(Sc)) of the variably N-glycosylated cellular prion protein (PrP(C)). In infected species, prions replicate by seeding the conversion and polymerization of host PrP(C). Distinct prion strains can be recognized, exhibiting defined PrP(Sc) biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrP(Sc) assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrP(C) glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrP(C) species of interest as substrate. Applying the technique to PrP(C) glycosylation mutants expressing cells revealed that neither PrP(C) nor PrP(Sc) glycoform stoichiometry was instrumental to PrP(Sc) formation and strainness perpetuation. Our study supports the view that strain properties, including PrP(Sc) glycotype are enciphered within PrP(Sc) structural backbone, not in the attached glycans.

  3. High Frequency Performance of SiGeC HBTs with Selectively & Non-Selectively Grown Collector

    NASA Astrophysics Data System (ADS)

    Suvar, Erdal; Haralson, Erik; Radamson, Henry H.; Wang, Yong-Bin; Malm, B. Gunnar; Östling, Mikael

    2004-01-01

    Two high-frequency heterojunction bipolar transistor (HBT) architectures based on SiGeC have been fabricated and characterized. Different collector designs were applied either by using selective epitaxial growth doped with phosphorous or by nonselective epitaxial growth doped with arsenic. Both designs have a nonselectively deposited SiGeC base doped with boron and a poly-crystalline emitter doped with phosphorous. Both HBT designs exhibit similar electrical characteristics with a peak DC current gain of around 1600 and a BVCEO of 1.8V. The cut-off frequency (fT) and maximum frequency of oscillation (fmax) vary from 40 80GHz and 15 30GHz, respectively, depending on lateral design relations. Good high frequency performance for a device with a selectively grown collector is demonstrated for the first time.

  4. Evaluation and selection of candidate high-level waste forms

    SciTech Connect

    Bernadzikowski, T. A.; Allender, J. S.; Butler, J. L.; Gordon, D. E.; Gould, Jr., T. H.; Stone, J. A.

    1982-03-01

    Seven candidate waste forms being developed under the direction of the Department of Energy's National High-Level Waste (HLW) Technology Program, were evaluated as potential media for the immobilization and geologic disposal of high-level nuclear wastes. The evaluation combined preliminary waste form evaluations conducted at DOE defense waste-sites and independent laboratories, peer review assessments, a product performance evaluation, and a processability analysis. Based on the combined results of these four inputs, two of the seven forms, borosilicate glass and a titanate based ceramic, SYNROC, were selected as the reference and alternative forms for continued development and evaluation in the National HLW Program. Both the glass and ceramic forms are viable candidates for use at each of the DOE defense waste-sites; they are also potential candidates for immobilization of commercial reprocessing wastes. This report describes the waste form screening process, and discusses each of the four major inputs considered in the selection of the two forms.

  5. Highly selective covalent organic functionalization of epitaxial graphene

    NASA Astrophysics Data System (ADS)

    Bueno, Rebeca A.; Martínez, José I.; Luccas, Roberto F.; Del Árbol, Nerea Ruiz; Munuera, Carmen; Palacio, Irene; Palomares, Francisco J.; Lauwaet, Koen; Thakur, Sangeeta; Baranowski, Jacek M.; Strupinski, Wlodek; López, María F.; Mompean, Federico; García-Hernández, Mar; Martín-Gago, José A.

    2017-05-01

    Graphene functionalization with organics is expected to be an important step for the development of graphene-based materials with tailored electronic properties. However, its high chemical inertness makes difficult a controlled and selective covalent functionalization, and most of the works performed up to the date report electrostatic molecular adsorption or unruly functionalization. We show hereafter a mechanism for promoting highly specific covalent bonding of any amino-terminated molecule and a description of the operating processes. We show, by different experimental techniques and theoretical methods, that the excess of charge at carbon dangling-bonds formed on single-atomic vacancies at the graphene surface induces enhanced reactivity towards a selective oxidation of the amino group and subsequent integration of the nitrogen within the graphene network. Remarkably, functionalized surfaces retain the electronic properties of pristine graphene. This study opens the door for development of graphene-based interfaces, as nano-bio-hybrid composites, fabrication of dielectrics, plasmonics or spintronics.

  6. Highly selective covalent organic functionalization of epitaxial graphene.

    PubMed

    Bueno, Rebeca A; Martínez, José I; Luccas, Roberto F; Del Árbol, Nerea Ruiz; Munuera, Carmen; Palacio, Irene; Palomares, Francisco J; Lauwaet, Koen; Thakur, Sangeeta; Baranowski, Jacek M; Strupinski, Wlodek; López, María F; Mompean, Federico; García-Hernández, Mar; Martín-Gago, José A

    2017-05-08

    Graphene functionalization with organics is expected to be an important step for the development of graphene-based materials with tailored electronic properties. However, its high chemical inertness makes difficult a controlled and selective covalent functionalization, and most of the works performed up to the date report electrostatic molecular adsorption or unruly functionalization. We show hereafter a mechanism for promoting highly specific covalent bonding of any amino-terminated molecule and a description of the operating processes. We show, by different experimental techniques and theoretical methods, that the excess of charge at carbon dangling-bonds formed on single-atomic vacancies at the graphene surface induces enhanced reactivity towards a selective oxidation of the amino group and subsequent integration of the nitrogen within the graphene network. Remarkably, functionalized surfaces retain the electronic properties of pristine graphene. This study opens the door for development of graphene-based interfaces, as nano-bio-hybrid composites, fabrication of dielectrics, plasmonics or spintronics.

  7. High avidity HSV-1 antibodies correlate with absence of amnestic Mild Cognitive Impairment conversion to Alzheimer's disease.

    PubMed

    Agostini, Simone; Mancuso, Roberta; Baglio, Francesca; Cabinio, Monia; Hernis, Ambra; Costa, Andrea Saul; Calabrese, Elena; Nemni, Raffaello; Clerici, Mario

    2016-11-01

    Amnestic Mild Cognitive Impairment (aMCI) is an alteration in cognitive abilities that can progress to Alzheimer's disease (AD), a condition in which herpes simplex type 1 (HSV-1) infection might play a pathogenetic role. Prognostic indexes capable of predicting aMCI conversion to AD are only partially understood. The objective of the present work is to verify whether HSV-1 immune responses is involved in conversion of aMCI to AD and correlate with grey matter brain morphometry. Two homogeneous groups of individuals who did or did not convert to AD over a 24-months period were selected after retrospective analysis of a cohort of patients with a diagnosis of aMCI. The selection of subjects was based on: a) clinical follow-up; b) neurocognitive evaluation at baseline and after 24months; c) availability of serum and DNA samples at baseline. 36 aMCI individuals, 21 of whom did (aMCI-converters) and 15 of whom did not (aMCI-non-converters) convert to AD, were included in the study. HSV-1 antibody (Ab) titers, avidity index and APOE genotyping were performed in all the enrolled individuals at baseline. Brain magnetic resonance imaging (MRI) by 1.5T scanner results at baseline were available as well in most (29/36) of these individuals. HSV-1-specific Ab titers were increased at baseline in aMCI-non-converters, and the avidity of these Ab was significantly higher in aMCI-non-converter compared to aMCI-converter (p=0.0018). Receiver operating characteristics analysis showed that HSV-1 avidity had a predictive value in distinguishing between aMCI-non-converters and aMCI-converters (p<0.0001). Notably, a positive correlation was detected as well between HSV-1 antibody titers and MRI-evaluated cortical volumes in the left hippocampus and amigdala (pcorr<0.05). In conclusion, stronger HSV-1-specific humoral responses associate with protection against AD conversion and better-preserved cortical volumes. These results reinforce the hypothesis for a role for HSV-1 in the

  8. Rapid Generation of Highly Specific Aptamers via Micromagnetic Selection

    PubMed Central

    Qian, Jiangrong; Lou, Xinhui; Zhang, Yanting; Xiao, Yi; Soh, H. Tom

    2009-01-01

    Aptamers are nucleic acid-based reagents that bind to target molecules with high affinity and specificity. However, methods for generating aptamers from random combinatorial libraries (e.g., SELEX) are often labor-intensive and time-consuming. Recent studies suggest that microfluidic SELEX (M-SELEX) technology can accelerate aptamer isolation by enabling highly stringent selection conditions through the use of very small amounts of target molecules. We present here an alternative M-SELEX method, which employs a disposable microfluidic chip to rapidly generate aptamers with high affinity and specificity. The Micro-Magnetic Separation (MMS) chip integrates microfabricated ferromagnetic structures to reproducibly generate large magnetic field gradients within its microchannel that efficiently trap magnetic bead-bound aptamers. Operation of the MMS device is facile, robust and demonstrates high recovery of the beads (99.5%), such that picomolar amounts of target molecule can be used. Importantly, the device demonstrates exceptional separation efficiency in removing weakly-bound and unbound ssDNA to rapidly enrich target-specific aptamers. As a model, we demonstrate here the generation of DNA aptamers against streptavidin in three rounds of positive selection. We further enhanced the specificity of the selected aptamers via a round of negative selection in the same device against bovine serum albumin (BSA). The resulting aptamers displayed dissociation constants ranging from 25 to 65 nM for streptavidin but negligible affinity for BSA. Since a wide spectrum of molecular targets can be readily conjugated on magnetic beads, MMS-based SELEX should provide a general platform for rapid generation of specific aptamers. PMID:19480397

  9. Selecting Salient Features in High Feature to Exemplar Ratio Conditions

    DTIC Science & Technology

    2002-03-01

    We present an approach for identifying salient input features in high feature to exemplar ratio conditions. Basically we modify the SNR saliency...screening algorithm to improve the solution of the optimal salient feature subset problem. We propose that applying the SNR method to randomly selected...subsets (SRSS) has a superior potential to identify the salient features than the traditional SNR algorithm has. Two experimental studies are provided

  10. Experimental characterization and modeling of a nanofiber-based selective emitter for thermophotovoltaic energy conversion: The effect of optical properties

    NASA Astrophysics Data System (ADS)

    Aljarrah, M. T.; Wang, R.; Evans, E. A.; Clemons, C. B.; Young, G. W.

    2011-02-01

    Aluminum oxide nanofibers doped with erbium oxide have been synthesized by calcining polymer fibers made by the electrospinning technique using a mixture of aluminum acetate, erbium acetate and polyvinylpyrrolidone dissolved in ethanol. The resulting ceramic fibers are used to fabricate a free-standing selective emitter. The general equation of radiation transfer coupled with experimentally measured optical properties is used to model the net radiation obtained from these structures. It has been found that the index of refraction and the extinction coefficient are direct functions of the erbia doping level in the fibers. The fibers radiated in a selective manner at ˜1.53 μm with an efficiency of about 90%. For a fiber film on a substrate, the effect of film thickness, extinction coefficient and substrate emissivity on the overall emitter emissivity is also investigated in this study. Results show that the emissivity of the film increases as the thickness of the film increases up to a maximum value, after which increasing the film thickness had no effect on emissivity. Furthermore, it has been found that the substrate emissivity increases the amount of off-band radiation. This effect can be mitigated by controlling the film thickness.

  11. Selecting sugarcane genotypes by the selection index reveals high gain for technological quality traits.

    PubMed

    Silva, L A; Teodoro, P E; Peixoto, L A; Assis, C; Gasparini, K; Barbosa, M H P; Bhering, L L

    2017-05-25

    Sugarcane (Saccharum sp) is one of the most promising crops and researchers have sought for renewable alternative energy sources to reduce CO2 emission. The study of strategies, which allow breeders in the selection of superior genotypes for many traits simultaneously, is important. Therefore, the objectives of this study were: i) to apply path analysis to better understand the relationship between the lignocellulosic traits and technological quality traits with total recoverable sugars (TRS) and ii) to use several multivariate selection indexes to predict the genetic gain and to select superior genotypes in the sugarcane breeding. A total of 40 sugarcane genotypes were evaluated in an experimental design using incomplete blocks with two replicates. The follow traits were evaluated: dry matter (DM), total soluble solids (BRIX), apparent sucrose content in the juice (POL), apparent sucrose content in sugarcane (POLS), fiber content (FIB), purity (PUR), TRS, lignin content (LC), cellulose content (CC), hemicellulose content (HC), and ash content (AC). These traits were analyzed by analysis of variance, phenotypic correlation network, path analysis, and selection index. The highest direct effect on TRS was obtained by POLS (0.337), POL (0.299), BRIX (0.227), and FIB (-0.146). The estimates of phenotypic correlation between these characters and TRS were in the same direction, which demonstrated a cause-and-effect relationship. The highest indirect effect was of POL via POLS (0.331) followed by POLS via POL (0.294). BRIX presented high indirect effects via POLS (0.266) and via POL (0.246). On the other hand, FIB presented negative indirect effects via POLS (-0.169) and POL (-0.103). In conclusion, path analysis and index selection are useful strategies to help breeders in the selection of superior genotypes in sugarcane.

  12. Join the Conversation: Are Students' Behaviors in College Classes Conditioned by Their Experiences in High School?

    ERIC Educational Resources Information Center

    Moore, Randy; Jensen, Philip A.

    2007-01-01

    Students in an introductory college biology course who believed that attending class had been important for their academic success in high school were 1) most likely to attend their college biology class, 2) most likely to earn high grades in their college biology class, 3) most likely to report that their high school classes had been challenging,…

  13. Development of a selective chemical etch to improve the conversion efficiency of Zn-rich Cu2ZnSnS4 solar cells.

    PubMed

    Fairbrother, Andrew; García-Hemme, Eric; Izquierdo-Roca, Victor; Fontané, Xavier; Pulgarín-Agudelo, Fabián A; Vigil-Galán, Osvaldo; Pérez-Rodríguez, Alejandro; Saucedo, Edgardo

    2012-05-16

    Improvement of the efficiency of Cu(2)ZnSnS(4) (CZTS)-based solar cells requires the development of specific procedures to remove or avoid the formation of detrimental secondary phases. The presence of these phases is favored by the Zn-rich and Cu-poor conditions that are required to obtain device-grade layers. We have developed a selective chemical etching process based on the use of hydrochloric acid solutions to remove Zn-rich secondary phases from the CZTS film surface, which are partly responsible for the deterioration of the series resistance of the cells and, as a consequence, the conversion efficiency. Using this approach, we have obtained CZTS-based devices with 5.2% efficiency, which is nearly twice that of the devices we have prepared without this etching process.

  14. Elucidating the Irreversible Mechanism and Voltage Hysteresis in Conversion Reaction for High-Energy Sodium-Metal Sulfide Batteries

    DOE PAGES

    Wang, Jiajun; Wang, Liguang; Eng, Christopher; ...

    2017-03-03

    We present that irreversible electrochemical behavior and large voltage hysteresis are commonly observed in battery materials, in particular for materials reacting through conversion reaction, resulting in undesirable round-trip energy loss and low coulombic efficiency. Seeking solutions to these challenges relies on the understanding of the underlying mechanism and physical origins. Here, this study combines in operando 2D transmission X-ray microscopy with X-ray absorption near edge structure, 3D tomography, and galvanostatic intermittent titration techniques to uncover the conversion reaction in sodium–metal sulfide batteries, a promising high-energy battery system. This study shows a high irreversible electrochemistry process predominately occurs at first cycle,more » which can be largely linked to Na ion trapping during the first desodiation process and large interfacial ion mobility resistance. Subsequently, phase transformation evolution and electrochemical reaction show good reversibility at multiple discharge/charge cycles due to materials' microstructural change and equilibrium. The origin of large hysteresis between discharge and charge is investigated and it can be attributed to multiple factors including ion mobility resistance at the two-phase interface, intrinsic slow sodium ion diffusion kinetics, and irreversibility as well as ohmic voltage drop and overpotential. In conclusion, this study expects that such understandings will help pave the way for engineering design and optimization of materials microstructure for future-generation batteries.« less

  15. Preliminary Accident Analyses for Conversion of the Massachusetts Institute of Technology Reactor (MITR) from Highly Enriched to Low Enriched Uranium

    SciTech Connect

    Dunn, Floyd E.; Olson, Arne P.; Wilson, Erik H.; Sun, Kaichao S.; Newton, Jr., Thomas H.; Hu, Lin-wen

    2013-09-30

    The Massachusetts Institute of Technology Reactor (MITR-II) is a research reactor in Cambridge, Massachusetts designed primarily for experiments using neutron beam and in-core irradiation facilities. It delivers a neutron flux comparable to current LWR power reactors in a compact 6 MW core using Highly Enriched Uranium (HEU) fuel. In the framework of its non-proliferation policies, the international community presently aims to minimize the amount of nuclear material available that could be used for nuclear weapons. In this geopolitical context most research and test reactors, both domestic and international, have started a program of conversion to the use of LEU fuel. A new type of LEU fuel based on an alloy of uranium and molybdenum (U-Mo) is expected to allow the conversion of U.S. domestic high performance reactors like MITR. This report presents the preliminary accident analyses for MITR cores fueled with LEU monolithic U-Mo alloy fuel with 10 wt% Mo. Preliminary results demonstrate adequate performance, including thermal margin to expected safety limits, for the LEU accident scenarios analyzed.

  16. A one-pot method for the selective conversion of hemicellulose from crop waste into C5 sugars and furfural by using solid acid catalysts.

    PubMed

    Sahu, Ramakanta; Dhepe, Paresh Laxmikant

    2012-04-01

    We present a solid-acid catalyzed one-pot method for the selective conversion of solid hemicellulose without its separation from other lignocellulosic components, such as cellulose and lignin. The reactions were carried out in aqueous and biphasic media to yield xylose, arabinose, and furfural. To overcome the drawbacks posed by mineral acid methods in converting hemicelllulose, we used heterogeneous catalysts that work at neutral pH. In a batch reactor, these heterogeneous catalysts, such as solid acids (zeolites, clays, metal oxides etc.), resulted in >90 % conversion of hemicellulose. It has been shown that the selectivity for the products can be tuned by changing the reaction conditions, for example, a reaction carried out in water at 170 °C for 1 h with HBeta (Si/Al=19) and HUSY (Si/Al=15) catalysts gave yields of 62 and 56 % for xylose and arabinose, respectively. With increased reaction time (6 h) and in presence of only water, HUSY resulted in yields of 30 % xylose + arabinose and 18 % furfural. However, in a biphasic reaction system (water + p-xylene, 170 °C, 6 h) yields of 56 % furfural with 17 % xylose+arabinose could be achieved. It was shown that with the addition of organic solvent the furfural yield could be increased from 18 to 56 %. Under optimized reaction conditions, >90 % carbon balance was observed. The study revealed that catalysts were recyclable with a 20 % drop in activity for each subsequent run. It was observed that temperature, pressure, reaction time, substrate to catalyst ratio, solvent, and so forth had an effect on product formation. The catalysts were characterized by means of X-ray diffraction, temperature-programmed desorption of NH(3), inductively coupled plasma spectroscopy, elemental analysis, and solid-state NMR ((29)Si, (27)Al) spectroscopy techniques.

  17. A Primer on High-Throughput Computing for Genomic Selection

    PubMed Central

    Wu, Xiao-Lin; Beissinger, Timothy M.; Bauck, Stewart; Woodward, Brent; Rosa, Guilherme J. M.; Weigel, Kent A.; Gatti, Natalia de Leon; Gianola, Daniel

    2011-01-01

    High-throughput computing (HTC) uses computer clusters to solve advanced computational problems, with the goal of accomplishing high-throughput over relatively long periods of time. In genomic selection, for example, a set of markers covering the entire genome is used to train a model based on known data, and the resulting model is used to predict the genetic merit of selection candidates. Sophisticated models are very computationally demanding and, with several traits to be evaluated sequentially, computing time is long, and output is low. In this paper, we present scenarios and basic principles of how HTC can be used in genomic selection, implemented using various techniques from simple batch processing to pipelining in distributed computer clusters. Various scripting languages, such as shell scripting, Perl, and R, are also very useful to devise pipelines. By pipelining, we can reduce total computing time and consequently increase throughput. In comparison to the traditional data processing pipeline residing on the central processors, performing general-purpose computation on a graphics processing unit provide a new-generation approach to massive parallel computing in genomic selection. While the concept of HTC may still be new to many researchers in animal breeding, plant breeding, and genetics, HTC infrastructures have already been built in many institutions, such as the University of Wisconsin–Madison, which can be leveraged for genomic selection, in terms of central processing unit capacity, network connectivity, storage availability, and middleware connectivity. Exploring existing HTC infrastructures as well as general-purpose computing environments will further expand our capability to meet increasing computing demands posed by unprecedented genomic data that we have today. We anticipate that HTC will impact genomic selection via better statistical models, faster solutions, and more competitive products (e.g., from design of marker panels to realized

  18. A primer on high-throughput computing for genomic selection.

    PubMed

    Wu, Xiao-Lin; Beissinger, Timothy M; Bauck, Stewart; Woodward, Brent; Rosa, Guilherme J M; Weigel, Kent A; Gatti, Natalia de Leon; Gianola, Daniel

    2011-01-01

    High-throughput computing (HTC) uses computer clusters to solve advanced computational problems, with the goal of accomplishing high-throughput over relatively long periods of time. In genomic selection, for example, a set of markers covering the entire genome is used to train a model based on known data, and the resulting model is used to predict the genetic merit of selection candidates. Sophisticated models are very computationally demanding and, with several traits to be evaluated sequentially, computing time is long, and output is low. In this paper, we present scenarios and basic principles of how HTC can be used in genomic selection, implemented using various techniques from simple batch processing to pipelining in distributed computer clusters. Various scripting languages, such as shell scripting, Perl, and R, are also very useful to devise pipelines. By pipelining, we can reduce total computing time and consequently increase throughput. In comparison to the traditional data processing pipeline residing on the central processors, performing general-purpose computation on a graphics processing unit provide a new-generation approach to massive parallel computing in genomic selection. While the concept of HTC may still be new to many researchers in animal breeding, plant breeding, and genetics, HTC infrastructures have already been built in many institutions, such as the University of Wisconsin-Madison, which can be leveraged for genomic selection, in terms of central processing unit capacity, network connectivity, storage availability, and middleware connectivity. Exploring existing HTC infrastructures as well as general-purpose computing environments will further expand our capability to meet increasing computing demands posed by unprecedented genomic data that we have today. We anticipate that HTC will impact genomic selection via better statistical models, faster solutions, and more competitive products (e.g., from design of marker panels to realized

  19. High and low gamma EEG oscillations in central sensorimotor areas are conversely modulated during the human gait cycle.

    PubMed

    Seeber, Martin; Scherer, Reinhold; Wagner, Johanna; Solis-Escalante, Teodoro; Müller-Putz, Gernot R

    2015-05-15

    Investigating human brain function is essential to develop models of cortical involvement during walking. Such models could advance the analysis of motor impairments following brain injuries (e.g., stroke) and may lead to novel rehabilitation approaches. In this work, we applied high-density EEG source imaging based on individual anatomy to enable neuroimaging during walking. To minimize the impact of muscular influence on EEG recordings we introduce a novel artifact correction method based on spectral decomposition. High γ oscillations (>60Hz) were previously reported to play an important role in motor control. Here, we investigate high γ amplitudes while focusing on two different aspects of a walking experiment, namely the fact that a person walks and the rhythmicity of walking. We found that high γ amplitudes (60-80Hz), located focally in central sensorimotor areas, were significantly increased during walking compared to standing. Moreover, high γ (70-90Hz) amplitudes in the same areas are modulated in relation to the gait cycle. Since the spectral peaks of high γ amplitude increase and modulation do not match, it is plausible that these two high γ elements represent different frequency-specific network interactions. Interestingly, we found high γ (70-90Hz) amplitudes to be coupled to low γ (24-40Hz) amplitudes, which both are modulated in relation to the gait cycle but conversely to each other. In summary, our work is a further step towards modeling cortical involvement during human upright walking. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Variable Selection for Support Vector Machines in Moderately High Dimensions

    PubMed Central

    Zhang, Xiang; Wu, Yichao; Wang, Lan; Li, Runze

    2015-01-01

    Summary The support vector machine (SVM) is a powerful binary classification tool with high accuracy and great flexibility. It has achieved great success, but its performance can be seriously impaired if many redundant covariates are included. Some efforts have been devoted to studying variable selection for SVMs, but asymptotic properties, such as variable selection consistency, are largely unknown when the number of predictors diverges to infinity. In this work, we establish a unified theory for a general class of nonconvex penalized SVMs. We first prove that in ultra-high dimensions, there exists one local minimizer to the objective function of nonconvex penalized SVMs possessing the desired oracle property. We further address the problem of nonunique local minimizers by showing that the local linear approximation algorithm is guaranteed to converge to the oracle estimator even in the ultra-high dimensional setting if an appropriate initial estimator is available. This condition on initial estimator is verified to be automatically valid as long as the dimensions are moderately high. Numerical examples provide supportive evidence. PMID:26778916