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Sample records for based direct conversion

  1. Photoelectrochemical based direct conversion systems

    SciTech Connect

    Kocha, S.; Arent, D.; Peterson, M.

    1995-09-01

    The goal of this research is to develop a stable, cost effective, photoelectrochemical based system that will split water upon illumination, producing hydrogen and oxygen directly, using sunlight as the only energy input. This type of direct conversion system combines a photovoltaic material and an electrolyzer into a single monolithic device. We report on our studies of two multifunction multiphoton photoelectrochemical devices, one based on the ternary semiconductor gallium indium phosphide, (GaInP{sub 2}), and the other one based on amorphous silicon carbide. We also report on our studies of the solid state surface treatment of GaInP{sub 2} as well as our continuing effort to develop synthetic techniques for the attachment of transition metal complexes to the surface of semiconductor electrodes. All our surface studies are directed at controlling the interface energetics and forming stable catalytic surfaces.

  2. Thermoacoustic compression based on alternating to direct gas flow conversion

    NASA Astrophysics Data System (ADS)

    Sun, D. M.; Wang, K.; Xu, Y.; Shen, Q.; Zhang, X. J.; Qiu, L. M.

    2012-05-01

    We present a remarkable thermoacoustically driven compression effect based on the conversion of gas flow from an alternating state to a direct state. The alternating gas flow is generated by the thermoacoustic effect in thermoacoustic engines, whereas direct gas flow is achieved by means of the flow rectification effect of check valves. A demonstrative thermoacoustic compressor consisting of two standing-wave thermoacoustic engines, two reservoirs, and three check valves is constructed for experimental investigation. With nitrogen as a working gas and an initial pressure of 2.4 MPa in all components, a usable pressure difference of 0.4 MPa is achieved, with the average gas pumping rate reaching 2.85 Nm3/h during the first 3 s of the compression process. The simple mechanical structure and thermally driven nature of the compressor show potential in gas compression, power generation, and refrigeration applications.

  3. Photoelectrochemical based direct conversion systems for hydrogen production

    SciTech Connect

    Kocha, S.; Peterson, M.; Arent, D.

    1996-10-01

    Photon driven, direct conversion systems consist of a light absorber and a water splitting catalyst as a monolithic system; water is split directly upon illumination. This one-step process eliminates the need to generate electricity externally and subsequently feed it to an electrolyzer. These configurations require only the piping necessary for transport of hydrogen to an external storage system or gas pipeline. This work is focused on multiphoton photoelectrochemical devices for production of hydrogen directly using sunlight and water. Two types of multijunction cells, one consisting of a-Si triple junctions and the other GaInP{sub 2}/GaAs homojunctions, were studied for the photoelectrochemical decomposition of water into hydrogen and oxygen from an aqueous electrolyte solution. To catalyze the water decomposition process, the illuminated surface of the device was modified either by addition of platinum colloids or by coating with ruthenium dioxide. These colloids have been characterized by gel electrophoresis.

  4. Direct Conversion Technology

    SciTech Connect

    Back, L.H.; Fabris, G.; Ryan, M.A.

    1992-07-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. Initially, two systems were selected for exploratory research and advanced development. These are Alkali Metal Thermal-to-Electric Converter (AMTEC) and Two-Phase Liquid Metal MD Generator (LMMHD). This report describes progress that has been made during the first six months of 1992 on research activities associated with these two systems. (GHH)

  5. Direct conversion technology

    SciTech Connect

    Massier, P.F.; Back, L.H.; Ryan, M.A.; Fabris, G.

    1992-01-07

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1, 1991 through December 31, 1991. Research on AMTEC and on LMMHD was initiated during October 1987. Reports prepared on previous occasions (Refs. 1--5) contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  6. Direct conversion technology

    NASA Technical Reports Server (NTRS)

    Massier, Paul F.; Bankston, C. P.; Williams, R.; Underwood, M.; Jeffries-Nakamura, B.; Fabris, G.

    1989-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal Magnetohydrodynamic Electrical Generator (LMMHD) for the period January 1, 1989 through December 31, 1989. Research on these concepts was initiated during October 1987. Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (nitinol heat engines); and also, more complete discussions of AMTEC and LMMHD systems.

  7. Direct Conversion of Energy.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

  8. Direct conversion technology

    NASA Technical Reports Server (NTRS)

    Massier, P. F.; Bankston, C. P.; Fabris, G.; Kirol, L. D.

    1988-01-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1988 through December 1988. Research on these concepts was initiated during October 1987. In addition, status reviews and assessments are presented for thermomagnetic converter concepts and for thermoelastic converters (Nitinol heat engines). Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic thermophotovoltaic and thermoacoustic; and also, more complete discussions of AMTEC and LMMHD systems. A tabulated summary of the various systems which have been reviewed thus far has been prepared. Some of the important technical research needs are listed and a schematic of each system is shown.

  9. Direct conversion technology

    NASA Astrophysics Data System (ADS)

    Massier, P. F.; Bankston, C. P.; Fabris, G.; Kirol, L. D.

    1988-12-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1988 through December 1988. Research on these concepts was initiated during October 1987. In addition, status reviews and assessments are presented for thermomagnetic converter concepts and for thermoelastic converters (Nitinol heat engines). Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic thermophotovoltaic and thermoacoustic; and also, more complete discussions of AMTEC and LMMHD systems. A tabulated summary of the various systems which have been reviewed thus far has been prepared. Some of the important technical research needs are listed and a schematic of each system is shown.

  10. Modified Direct Insertion/Cancellation Method Based Sample Rate Conversion for Software Defined Radio

    NASA Astrophysics Data System (ADS)

    Bostamam, Anas Muhamad; Sanada, Yukitoshi; Minami, Hideki

    In this paper, a new fractional sample rate conversion (SRC) scheme based on a direct insertion/cancellation scheme is proposed. This scheme is suitable for signals that are sampled at a high sample rate and converted to a lower sample rate. The direct insertion/cancellation scheme may achieve low-complexity and lower power consumption as compared to the other SRC techniques. However, the direct insertion/cancellation technique suffers from large aliasing and distortion. The aliasing from an adjacent channel interferes the desired signal and degrades the performance. Therefore, a modified direct insertion/cancellation scheme is proposed in order to realize high performance resampling.

  11. Direct somatic lineage conversion

    PubMed Central

    Tanabe, Koji; Haag, Daniel; Wernig, Marius

    2015-01-01

    The predominant view of embryonic development and cell differentiation has been that rigid and even irreversible epigenetic marks are laid down along the path of cell specialization ensuring the proper silencing of unrelated lineage programmes. This model made the prediction that specialized cell types are stable and cannot be redirected into other lineages. Accordingly, early attempts to change the identity of somatic cells had little success and was limited to conversions between closely related cell types. Nuclear transplantation experiments demonstrated, however, that specialized cells even from adult mammals can be reprogrammed into a totipotent state. The discovery that a small combination of transcription factors can reprogramme cells to pluripotency without the need of oocytes further supported the view that these epigenetic barriers can be overcome much easier than assumed, but the extent of this flexibility was still unclear. When we showed that a differentiated mesodermal cell can be directly converted to a differentiated ectodermal cell without a pluripotent intermediate, it was suggested that in principle any cell type could be converted into any other cell type. Indeed, the work of several groups in recent years has provided many more examples of direct somatic lineage conversions. Today, the question is not anymore whether a specific cell type can be generated by direct reprogramming but how it can be induced. PMID:26416679

  12. Direct digital conversion detector technology

    NASA Astrophysics Data System (ADS)

    Mandl, William J.; Fedors, Richard

    1995-06-01

    Future imaging sensors for the aerospace and commercial video markets will depend on low cost, high speed analog-to-digital (A/D) conversion to efficiently process optical detector signals. Current A/D methods place a heavy burden on system resources, increase noise, and limit the throughput. This paper describes a unique method for incorporating A/D conversion right on the focal plane array. This concept is based on Sigma-Delta sampling, and makes optimum use of the active detector real estate. Combined with modern digital signal processors, such devices will significantly increase data rates off the focal plane. Early conversion to digital format will also decrease the signal susceptibility to noise, lowering the communications bit error rate. Computer modeling of this concept is described, along with results from several simulation runs. A potential application for direct digital conversion is also reviewed. Future uses for this technology could range from scientific instruments to remote sensors, telecommunications gear, medical diagnostic tools, and consumer products.

  13. Direct Energy Conversion Literature Abstracts

    DTIC Science & Technology

    1962-12-01

    HOMOPOLAR Apparatus needed to fabricate and test MOTOR , by G. J. Bukow. 46p., Jan. 1961. candidate junction materials and modules (ASD TR-61-101...small homopolar motor as a 3085 component of a thermoelectric energy- NEW TYPE OF THERMOELECTRIC GENER- conversion system, utilizing the low- ATOR...CONVERSION AND HEAT-TRANSFER are silent outboard motors and power FLUIDS FCR SPACE APPLICATIONS, by lawnmiowers. W. D. Weatherford, J.C. Tyler and P. M

  14. Direct optical to microwave conversion

    NASA Astrophysics Data System (ADS)

    Taylor, Henry F.

    1990-09-01

    Support of high frequency fiber optic links through development of innovative higher efficiency techniques to convert optical energy directly to RF Energy. Control of Phases Arrays by optical means in an area of expanding technology development. Fiber optics and other forms of optical waveguide can provide greater accuracy and true time delay in a phase delay network. Methods of improvement in transfer of optical energy to RF Energy are determined. Development of Direct Optical-to-RF-Direct Amplifiers will result in higher efficiency, low noise, optical receivers for fiber optic links with improved performance. This results in longer fiber optic links without repeaters and improved BER or shorter links.

  15. Direct and converse magneto-electric coupling in ferromagnetic shape memory alloys based thin film multiferroic heterostructures

    NASA Astrophysics Data System (ADS)

    Singh, Kirandeep; Kaur, Davinder

    2015-12-01

    The ferromagnetic shape memory driven alterations in strain mediated direct and converse magnetoelectric coupling (DME & CME) was realized in sputtered deposited PZT/Ni-Mn-In multiferroic hetero-junctions. The ferroelectric (P-E loops), dielectric (ɛ vs frequency, ɛ-E), and voltage modulated magnetic anisotropy measurements (M-E curves) were executed in the plane (hard axis) and out of the plane (easy axis) of the functional magnetic material based PZT/Ni-Mn-In bilayer structure. A gain of ˜16 μC/cm2 in maximum polarization (Pmax) and ˜12% in tunability (nr) were observed along an easy magnetic axis of Ni-Mn-In. The butterfly shaped normalized magnetization (M/Ms) vs electric field (applied across the heterostructure) [M-E] plots evident the strain character of CME coupling. The co-action of (i) dissimilar carrier concentration between high symmetric austenitic cubic phase and low symmetry martensite phase of ferromagnetic shape memory alloys and (ii) martensitic transformation induced magnetization change in Ni-Mn-In cause an electrical field modulated hall resistivity; a change of ˜42% in hall resistivity was observed at 60 kV/cm electric field and 0.2 T magnetic field at 270 K. The reversible manipulation of remnant magnetization (Mr) with applied electric field was demonstrated as on/off switch using a square pulse of 60 kV/cm amplitude.

  16. Direct Energy Conversion Literature Abstracts

    DTIC Science & Technology

    1963-12-01

    electrical at 100-200 0 C. with concentrated potassium energy by electrolysis of water and hydroxide or an ion exchange resin as the subsequent recombination...directly into elec- output of solar energy converters is used trical or thrust energy. to produce hydrogen by pressure elec- trolysis of water . The energy...ELECTRICAL Solar energy collectors, heat exchangers ENERGY WITH FERROELECTRIC MATERIALS. Inst. etc. are considered for water -heating, Elec.4

  17. Mechanically stable, hierarchically porous Cu3(btc)2 (HKUST-1) monoliths via direct conversion of copper(II) hydroxide-based monoliths.

    PubMed

    Moitra, Nirmalya; Fukumoto, Shotaro; Reboul, Julien; Sumida, Kenji; Zhu, Yang; Nakanishi, Kazuki; Furukawa, Shuhei; Kitagawa, Susumu; Kanamori, Kazuyoshi

    2015-02-28

    The synthesis of highly crystalline macro-meso-microporous monolithic Cu3(btc)2 (HKUST-1; btc(3-) = benzene-1,3,5-tricarboxylate) is demonstrated by direct conversion of Cu(OH)2-based monoliths while preserving the characteristic macroporous structure. The high mechanical strength of the monoliths is promising for possible applications to continuous flow reactors.

  18. Direct Conversion of Bio-ethanol to Isobutene on Nanosized ZnxZryOz Mixed Oxides with Balanced Acid–Base Sites

    SciTech Connect

    Sun, Junming; Zhu, Kake; Gao, Feng; Wang, Chong M.; Liu, Jun; Peden, Charles HF; Wang, Yong

    2011-06-17

    Bio-mass conversion has attracted increasing research interests to produce bio-fuels with bio-ethanol being a major product. Development of advanced processes to further upgrade bio-ethanol to other value added fuels or chemicals are pivotal to improving the economics of biomass conversion and deversifying the utilization of biomass resources. In this paper, for the first time, we report the direct conversion of bio-ethanol to isobutene with high yield (~83%) on a multifunctional ZnxZryOz mixed oxide with a dedicated balance of surface acid-base properties. This work illustrates the significance of rational design of a multifunctional mixed oxide catalyst for one step bio-ethanol conversion to a value-added intermediate, isobutene, for chemical and fuel production. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  19. Direct conversion of algal biomass to biofuel

    DOEpatents

    Deng, Shuguang; Patil, Prafulla D; Gude, Veera Gnaneswar

    2014-10-14

    A method and system for providing direct conversion of algal biomass. Optionally, the method and system can be used to directly convert dry algal biomass to biodiesels under microwave irradiation by combining the reaction and combining steps. Alternatively, wet algae can be directly processed and converted to fatty acid methyl esters, which have the major components of biodiesels, by reacting with methanol at predetermined pressure and temperature ranges.

  20. Role of precursor chemistry in the direct fluorination to form titanium based conversion anodes for lithium ion batteries

    SciTech Connect

    Adcock, Jamie; Dai, Sheng; Veith, Gabriel M.; Bridges, Craig A.; Powell, Jonathan M.

    2015-10-13

    In this study, a new synthetic route for the formation of titanium oxydifluoride (TiOF2) through the process of direct fluorination via a fluidized bed reactor system and the associated electrochemical properties of the powders formed from this approach are reported. The flexibility of this synthetic route was demonstrated using precursor powders of titanium dioxide (TiO2) nanoparticles, as well as a reduced TiOxNy. An advantage of this synthetic method is the ability to directly control the extent of fluorination as a function of reaction temperature and time. The reversible capacity of TiOF2 anodes was found to depend greatly upon the precursor employed. The TiOF2 synthesized from TiO2 and TiOxNy showed reversible capacities of 300 mAh g-1 and 440 mAh g-1, respectively, over 100 cycles. The higher reversible capacity of the TiOF2 powders derived from TiOxNy likely relate to the partial reduction of the Ti in the fluorinated electrode material, highlighting a route to optimize the properties of conversion electrode materials.

  1. Role of precursor chemistry in the direct fluorination to form titanium based conversion anodes for lithium ion batteries

    DOE PAGES

    Adcock, Jamie; Dai, Sheng; Veith, Gabriel M.; ...

    2015-10-13

    In this study, a new synthetic route for the formation of titanium oxydifluoride (TiOF2) through the process of direct fluorination via a fluidized bed reactor system and the associated electrochemical properties of the powders formed from this approach are reported. The flexibility of this synthetic route was demonstrated using precursor powders of titanium dioxide (TiO2) nanoparticles, as well as a reduced TiOxNy. An advantage of this synthetic method is the ability to directly control the extent of fluorination as a function of reaction temperature and time. The reversible capacity of TiOF2 anodes was found to depend greatly upon the precursormore » employed. The TiOF2 synthesized from TiO2 and TiOxNy showed reversible capacities of 300 mAh g-1 and 440 mAh g-1, respectively, over 100 cycles. The higher reversible capacity of the TiOF2 powders derived from TiOxNy likely relate to the partial reduction of the Ti in the fluorinated electrode material, highlighting a route to optimize the properties of conversion electrode materials.« less

  2. Direct Energy Conversion for Fast Reactors

    SciTech Connect

    Brown, N.; Cooper, J.; Vogt, D.; Chapline, G.; Turchi, P.; Barbee Jr., T.; Farmer, J.

    2000-07-01

    Thermoelectric generators (TEG) are a well-established technology for compact low power output long-life applications. Solid state TEGs are the technology of choice for many space missions and have also been used in remote earth-based applications. Since TEGs have no moving parts and can be hermetically sealed, there is the potential for nuclear reactor power systems using TEGs to be safe, reliable and resistant to proliferation. Such power units would be constructed in a manner that would provide decades of maintenance-free operation, thereby minimizing the possibility of compromising the system during routine maintenance operations. It should be possible to construct an efficient direct energy conversion cascade from an appropriate combination of solid-state thermoelectric generators, with each stage in the cascade optimized for a particular range of temperature. Performance of cascaded thermoelectric devices could be further enhanced by exploitation of compositionally graded p-n couples, as well as radial elements to maximize utilization of the heat flux. The Jet Propulsion Laboratory in Pasadena has recently reported segmented unicouples that operate between 300 and 975 K and have conversion efficiencies of 15 percent [Caillat, 2000]. TEGs are used in nuclear-fueled power sources for space exploration, in power sources for the military, and in electrical generators on diesel engines. Second, there is a wide variety of TE materials applicable to a broad range of temperatures. New materials may lead to new TEG designs with improved thermoelectric properties (i.e. ZT approaching 3) and significantly higher efficiencies than in designs using currently available materials. Computational materials science (CMS) has made sufficient progress and there is promise for using these techniques to reduce the time and cost requirements to develop such new TE material combinations. Recent advances in CMS, coupled with increased computational power afforded by the Accelerated

  3. Direct energy conversion using liquid metals

    NASA Astrophysics Data System (ADS)

    Onea, Alexandru; Diez de los Rios Ramos, Nerea; Hering, Wolfgang; Stieglitz, Robert; Moster, Peter

    2014-12-01

    Liquid metals have excellent properties to be used as heat transport fluids due to their high thermal conductivity and their wide applicable temperature range. The latter issue can be used to go beyond limitations of existing thermal solar energy systems. Furthermore, the direct energy converter Alkali Metal Thermo Electric Converter (AMTEC) can be used to make intangible areas of energy conversion suitable for a wide range of applications. One objective is to investigate AMTEC as a complementary cycle for the next generation of concentrating solar power (CSP) systems. The experimental research taking place in the Karlsruhe Institute of Technology (KIT) is focused on the construction of a flexible AMTEC test facility, development, test and improvement of liquid-anode and vapor-anode AMTEC devices as well as the coupling of the AMTEC cold side to the heat storage tank proposed for the CSP system. Within this project, the investigations foreseen will focus on the analyses of BASE-metal interface, electrode materials and deposition techniques, corrosion and erosion of materials brought in contact with high temperature sodium. This prototype demonstrator is planned to be integrated in the KArlsruhe SOdium LAboratory (KASOLA), a flexible closed mid-size sodium loop, completely in-house designed, presently under construction at the Institute for Neutron Physics and Reactor Technology (INR) within KIT.

  4. High-performance direct conversion X-ray detectors based on sintered hybrid lead triiodide perovskite wafers

    NASA Astrophysics Data System (ADS)

    Shrestha, Shreetu; Fischer, René; Matt, Gebhard J.; Feldner, Patrick; Michel, Thilo; Osvet, Andres; Levchuk, Ievgen; Merle, Benoit; Golkar, Saeedeh; Chen, Haiwei; Tedde, Sandro F.; Schmidt, Oliver; Hock, Rainer; Rührig, Manfred; Göken, Mathias; Heiss, Wolfgang; Anton, Gisela; Brabec, Christoph J.

    2017-07-01

    Lead halide perovskite semiconductors are in general known to have an inherently high X-ray absorption cross-section and a significantly higher carrier mobility than any other low-temperature solution-processed semiconductor. So far, the processing of several-hundred-micrometres-thick high-quality crystalline perovskite films over a large area has been unresolved for efficient X-ray detection. In this Article, we present a mechanical sintering process to fabricate polycrystalline methyl ammonium lead triiodide perovskite (MAPbI3) wafers with millimetre thickness and well-defined crystallinity. Benchmarking of the MAPbI3 wafers against state-of-the-art CdTe detectors reveals competitive conversion efficiencies of 2,527 µC Gyair-1 cm-2 under 70 kVp X-ray exposure. The high ambipolar mobility-lifetime product of 2 × 10-4 cm2 V-1 is suggested to be responsible for this exceptionally high sensitivity. Our findings inform a new generation of highly efficient and low-cost X-ray detectors based on perovskite wafers.

  5. Carbon aerogel electrodes for direct energy conversion

    DOEpatents

    Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

    1997-02-11

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes is described, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome. 1 fig.

  6. Carbon aerogel electrodes for direct energy conversion

    DOEpatents

    Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

    1997-01-01

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

  7. NEBNext Direct: A Novel, Rapid, Hybridization-Based Approach for the Capture and Library Conversion of Genomic Regions of Interest.

    PubMed

    Emerman, Amy B; Bowman, Sarah K; Barry, Andrew; Henig, Noa; Patel, Kruti M; Gardner, Andrew F; Hendrickson, Cynthia L

    2017-07-05

    Next-generation sequencing (NGS) is a powerful tool for genomic studies, translational research, and clinical diagnostics that enables the detection of single nucleotide polymorphisms, insertions and deletions, copy number variations, and other genetic variations. Target enrichment technologies improve the efficiency of NGS by only sequencing regions of interest, which reduces sequencing costs while increasing coverage of the selected targets. Here we present NEBNext Direct(®) , a hybridization-based, target-enrichment approach that addresses many of the shortcomings of traditional target-enrichment methods. This approach features a simple, 7-hr workflow that uses enzymatic removal of off-target sequences to achieve a high specificity for regions of interest. Additionally, unique molecular identifiers are incorporated for the identification and filtering of PCR duplicates. The same protocol can be used across a wide range of input amounts, input types, and panel sizes, enabling NEBNext Direct to be broadly applicable across a wide variety of research and diagnostic needs. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  8. Direct Carbon Conversion: Application to the Efficient Conversion of Fossil Fuels to Electricity

    SciTech Connect

    Cooper, J F; Cherepy, N; Berry, G; Pasternak, A; Surles, T; Steinberg, M

    2001-03-07

    We introduce a concept for efficient conversion of fossil fuels to electricity that entails the decomposition of fossil-derived hydrocarbons into carbon and hydrogen, and electrochemical conversion of these fuels in separate fuel cells. Carbon/air fuel cells have the advantages of near zero entropy change and associated heat production (allowing 100% theoretical conversion efficiency). The activities of the C fuel and CO{sub 2} product are invariant, allowing constant EMF and full utilization of fuel in single pass mode of operation. System efficiency estimates were conducted for several routes involving sequential extraction of a hydrocarbon from the fossil resource by (hydro) pyrolysis followed by thermal decomposition. The total energy conversion efficiencies of the processes were estimated to be (1) 80% for direct conversion of petroleum coke; (2) 67% HHV for CH{sub 4}; (3) 72% HHV for heavy oil (modeled using properties of decane); (4) 75.5% HHV (83% LHV) for natural gas conversion with a Rankine bottoming cycle for the H{sub 2} portion; and (5) 69% HHV for conversion of low rank coals and lignite through hydrogenation and pyrolysis of the CH{sub 4} intermediate. The cost of carbon fuel is roughly $7/GJ, based on the cost of the pyrolysis step in the industrial furnace black process. Cell hardware costs are estimated to be less than $500/kW.

  9. Investigation of direct solar-to-microwave energy conversion techniques

    NASA Technical Reports Server (NTRS)

    Chatterton, N. E.; Mookherji, T. K.; Wunsch, P. K.

    1978-01-01

    Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive with current baseline concepts. The most direct methods of conversion appear to require an initial step of production of coherent laser radiation. Other methods generally require production of electron streams for use in solid-state or cavity-oscillator systems. Further development is suggested to be worthwhile for suggested devices and on concepts utilizing a free-electron stream for the intraspace station power transport mechanism.

  10. Direct-conversion receiver for HiperLAN2

    NASA Astrophysics Data System (ADS)

    Gu, Jian

    2001-11-01

    A direct conversion receiver is presented for HiperLAN2 system that uses Orthogonal Frequency Division Multiplexing (OFDM) as its modulation scheme with data rate up to 54 Mbits/second. The direct conversion scheme converts the RF signal directly into a complex low-pass equivalent signal represented by in- phase (I) and quadrature (Q) components or so called I-Q base- band signal without any Intermediate Frequency (IF) stages and expensive Surface-Acoustic-Wave (SAW) filters. However, for a direct conversion receiver there are many key issues to be solved. One of the most important issues is so-called I-Q imbalance caused by the mismatch between I channel and Q channel of the quadrature demodulator. The I-Q imbalance may include gain and group delay difference between the I channel and the Q channel at any frequency within the low-pass signal bandwidth. With the patent-pending IQ-BalancingTM technology and other proprietary technologies of 4D Connect, inc., the adverse effects of I-Q imbalance on the receiver performance can be removed. Fixed-point simulation results for sensitivity performance and interference performance are presented. Performance comparisons when severe I-Q imbalance is present are also given.

  11. Direct conversion of bio-ethanol to isobutene on nanosized Zn(x)Zr(y)O(z) mixed oxides with balanced acid-base sites.

    PubMed

    Sun, Junming; Zhu, Kake; Gao, Feng; Wang, Chongmin; Liu, Jun; Peden, Charles H F; Wang, Yong

    2011-07-27

    We report the design and synthesis of nanosized Zn(x)Zr(y)O(z) mixed oxides for direct and high-yield conversion of bio-ethanol to isobutene (~83%). ZnO is addded to ZrO(2) to selectively passivate zirconia's strong Lewis acidic sites and weaken Brönsted acidic sites, while simultaneously introducing basicity. As a result, the undesired reactions of bio-ethanol dehydration and acetone polymerization/coking are suppressed. Instead, a surface basic site-catalyzed ethanol dehydrogenation to acetaldehyde, acetaldehyde to acetone conversion via a complex pathway including aldol-condensation/dehydrogenation, and a Brönsted acidic site-catalyzed acetone-to-isobutene reaction pathway dominates on the nanosized Zn(x)Zr(y)O(z) mixed oxide catalyst, leading to a highly selective process for direct conversion of bio-ethanol to isobutene.

  12. Generation of diverse neural cell types through direct conversion

    PubMed Central

    Petersen, Gayle F; Strappe, Padraig M

    2016-01-01

    A characteristic of neurological disorders is the loss of critical populations of cells that the body is unable to replace, thus there has been much interest in identifying methods of generating clinically relevant numbers of cells to replace those that have been damaged or lost. The process of neural direct conversion, in which cells of one lineage are converted into cells of a neural lineage without first inducing pluripotency, shows great potential, with evidence of the generation of a range of functional neural cell types both in vitro and in vivo, through viral and non-viral delivery of exogenous factors, as well as chemical induction methods. Induced neural cells have been proposed as an attractive alternative to neural cells derived from embryonic or induced pluripotent stem cells, with prospective roles in the investigation of neurological disorders, including neurodegenerative disease modelling, drug screening, and cellular replacement for regenerative medicine applications, however further investigations into improving the efficacy and safety of these methods need to be performed before neural direct conversion becomes a clinically viable option. In this review, we describe the generation of diverse neural cell types via direct conversion of somatic cells, with comparison against stem cell-based approaches, as well as discussion of their potential research and clinical applications. PMID:26981169

  13. Direct conversion technology: Annual summary report CY 1988

    SciTech Connect

    Massier, P.F.; Bankston, C.P.; Fabris, G.; Kirol, L.D.

    1988-12-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct thermal-to-electric energy conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC), and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1988 through December 1988. Research on these concepts was initiated during October 1987. In addition, status reviews and assessments are presented for thermomagnetic converter concepts and for thermoelastic converters (Nitinol heat engines). Reports prepared on previous occasions contain discussions on the following other direct conversion concepts: thermoelectric, pyroelectric, thermionic thermophotovoltaic and thermoacoustic; and also, more complete discussions of AMTEC and LMMHD systems. A tabulated summary of the various systems which have been reviewed thus far has been prepared. Some of the important technical research needs are listed and a schematic of each system is shown. These tabulations are included herein as figures. 43 refs., 26 figs., 1 tab.

  14. Direct Conversion Through Trans-Differentiation: Efficacy and Safety.

    PubMed

    Prasad, Ankshita; Teh, Daniel Boon Loong; Shah Jahan, Fathima R; Manivannan, Janani; Chua, Soo Min; All, Angelo H

    2017-02-01

    Direct conversion through transdifferentiation is a promising cell reprogramming approach that induces a cell lineage conversion among adult cells without passing through an intermediate pluripotent phase. However, there is a need to critically evaluate the efficacy and safety of direct conversion to establish its feasibility as a clinically viable cell reprogramming technique. This review article aims to delineate some critical constraints of direct conversion as a cellular reprogramming approach. We report the most important challenges of lineage reprogramming through direct conversion and divide them into two major sections. The first section explores the obstacles that limit the efficiency of the direct conversion process. In this study, we discuss challenges such as lack of understanding of molecular mechanism and transcriptional control of direct conversion, low proliferative capacity of converted cells, and senescence and apoptosis as critical barriers of direct conversion. The second section focuses on addressing concerns of safety of directly converted cells. We describe issues of transgene load and epigenetic memory retention along with the constraints of currently available validation tools to characterize reprogrammed cells. Each issue mentioned above is evaluated in view of their origin, implications, progress made toward their resolution and scope for development of new strategies to address the constraints of the present technique.

  15. Inequivalence of direct and converse magnetoelectric coupling at electromechanical resonance

    NASA Astrophysics Data System (ADS)

    Wu, Gaojian; Nan, Tianxiang; Zhang, Ru; Zhang, Ning; Li, Shandong; Sun, Nian X.

    2013-10-01

    Resonant direct and converse magnetoelectric (ME) effects have been investigated experimentally and theoretically in FeGa/PZT/FeGa sandwich laminate composites under the same electric and magnetic bias conditions. Resonant direct ME effect (DME) occurs at antiresonance frequency while resonant converse ME effect (CME) occurs at resonance frequency. The antiresonance and resonance frequencies have close but different values under identical bias conditions. The magnitudes of resonant effective ME coefficients for direct and converse ME effects are also not equal. A model was developed to describe the frequency response of DME and CME in laminate composite, which was in good agreement with experimental results.

  16. [Correlation between basic imaging properties and subjective evaluations of two digital radiographic X-ray systems based on direct-conversion flat panel detector].

    PubMed

    Sakaguchi, Taro; Katayama, Reiji; Morishita, Junji; Sakai, Shinji; Kuroki, Hidefumi; Ohkubo, Seiji; Maeda, Takashi; Hayabuchi, Naofumi

    2010-11-20

    The purpose of this study was to examine the correlation between the basic imaging properties of two digital radiographic X-ray systems with a direct conversion flat-panel detector and their image qualities, which were evaluated by the observer in hard copy and soft copy studies. The subjective image quality was evaluated and compared in terms of the low-contrast detectability and image sharpness in the two digital radiographic X-ray systems. We applied the radiographs of a contrast detail phantom to the evaluation of low-contrast detectability and analyzed the contrast detail diagrams. Finally, low-contrast detectability was evaluated by the image quality figure (IQF) calculated from the contrast detail diagrams. Also, the subjective image sharpness of human dry bones of two systems was examined and evaluated by the normalized-rank method. The results indicated that System A tended to provide superior subjective image quality compared to System B in both observer studies. We also found high correlations between IQFs and basic imaging properties, such as the noise power spectrum (NPS) and the noise equivalent quantum (NEQ). In conclusion, the low-contrast detectability of the two digital radiographic X-ray systems with a direct conversion flat-panel detector corresponded to the NPS and the NEQ in both outputs (soft copy and hard copy). On the other hand, the subjective image sharpness of human dry bones was affected by their noise properties.

  17. 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.

  18. Direct electrochemical conversion of carbon: systems for efficient conversion of fossil fuels to electricity

    SciTech Connect

    Cooper, J F; Cherepy, N; Krueger, R

    2000-08-10

    The direct electrochemical conversion of carbon involves discharge of suspensions of reactive carbon particles in a molten salt electrolyte against an oxygen (air) cathode. (Figure 1). The free energy and the enthalpy of the oxidation reaction are nearly identical. This allows theoretical efficiencies ({Delta}G(T)/{Delta}H) to approach 100% at temperatures from 500 to 800 C. Entropy heat losses are therefore negligible. The activities of the elemental carbon and of the carbon dioxide product are uniform throughout the fuel cell and constant over discharge time. This stabilizes cell EMF and allows full utilization of the carbon fuel in a single pass. Finally, the energy cost for pyrolysis of hydrocarbons is generally very low compared with that of steam reforming or water gas reactions. Direct electrochemical conversion of carbon might be compared with molten carbonate fuel cell using carbon rather than hydrogen. However, there are important differences. There is no hydrogen involved (except from trace water contamination). The mixture of molten carbonate and carbon is not highly flammable. The carbon is introduced in as a particulate, rather than as a high volume flow of hydrogen. At the relatively low rates of discharge (about 1 kA/m{sup 2}), the stoichiometric requirements for carbon dioxide by the cathodic reaction may be met by diffusion across the thin electrolyte gap. We report recent experimental work at LLNL using melt slurries of reactive carbons produced by the thermal decomposition of hydrocarbons. We have found that anodic reactivity of carbon in mixed carbonate melts depends strongly on form, structure and nano-scale disorder of the materials, which are fixed by the hydrocarbon starting material and the conditions of pyrolysis. Thus otherwise chemically pure carbons made by hydrocarbon pyrolysis show rates at fixed potentials that span an order of magnitude, while this range lies 1-2 orders of magnitude higher than the current density of graphite plate

  19. Reflection during Portfolio-Based Conversations

    ERIC Educational Resources Information Center

    Oosterbaan, Anne E.; van der Schaaf, Marieke F.; Baartman, Liesbeth K. J.; Stokking, Karel M.

    2010-01-01

    This study aims to explore the relationship between the occurrence of reflection (and non-reflection) and thinking activities (e.g., orientating, selecting, analysing) during portfolio-based conversations. Analysis of 21 transcripts of portfolio-based conversations revealed that 20% of the segments were made up of reflection (content reflection…

  20. Reflection during Portfolio-Based Conversations

    ERIC Educational Resources Information Center

    Oosterbaan, Anne E.; van der Schaaf, Marieke F.; Baartman, Liesbeth K. J.; Stokking, Karel M.

    2010-01-01

    This study aims to explore the relationship between the occurrence of reflection (and non-reflection) and thinking activities (e.g., orientating, selecting, analysing) during portfolio-based conversations. Analysis of 21 transcripts of portfolio-based conversations revealed that 20% of the segments were made up of reflection (content reflection…

  1. Direct conversion of human fibroblasts to dopaminergic neurons

    PubMed Central

    Pfisterer, Ulrich; Kirkeby, Agnete; Torper, Olof; Wood, James; Nelander, Jenny; Dufour, Audrey; Björklund, Anders; Lindvall, Olle; Jakobsson, Johan; Parmar, Malin

    2011-01-01

    Recent reports demonstrate that somatic mouse cells can be directly converted to other mature cell types by using combined expression of defined factors. Here we show that the same strategy can be applied to human embryonic and postnatal fibroblasts. By overexpression of the transcription factors Ascl1, Brn2, and Myt1l, human fibroblasts were efficiently converted to functional neurons. We also demonstrate that the converted neurons can be directed toward distinct functional neurotransmitter phenotypes when the appropriate transcriptional cues are provided together with the three conversion factors. By combining expression of the three conversion factors with expression of two genes involved in dopamine neuron generation, Lmx1a and FoxA2, we could direct the phenotype of the converted cells toward dopaminergic neurons. Such subtype-specific induced neurons derived from human somatic cells could be valuable for disease modeling and cell replacement therapy. PMID:21646515

  2. Key Roles of Lewis Acid-base Pairs on ZnxZryOz in Direct Ethanol/Acetone to Isobutene Conversion

    SciTech Connect

    Sun, Junming; Baylon, Rebecca A.; Liu, Changjun; Mei, Donghai; Martin, Kevin J.; Venkitasubramanian, Padmesh; Wang, Yong

    2016-01-20

    The effects of surface acidity on the cascade ethanol-to-isobutene conversion were studied using ZnxZryOz catalysts. The ethanol-to-isobutene reaction was found to be limited by the secondary reaction of the key intermediate, acetone, namely the acetone-to-isobutene reaction. Although the catalysts with coexisting Brønsted acidity could catalyze the rate-limiting acetone-to-isobutene reaction, the presence of Brønsted acidity is also detrimental. First, secondary isobutene isomerization is favored, producing a mixture of butene isomers. Second, undesired polymerization and coke formation prevail, leading to rapid catalyst deactivation. Most importantly, both steady-state and kinetic reaction studies as well as FTIR analysis of adsorbed acetone-d6 and D2O unambiguously showed that a highly active and selective nature of balanced Lewis acid-base pairs was masked by the coexisting Brønsted acidity in the aldolization and self-deoxygenation of acetone to isobutene. As a result, ZnxZryOz catalysts with only Lewis acid-base pairs were discovered, on which nearly a theoretical selectivity to isobutene (~88.9%) was successfully achieved, which has never been reported before. Moreover, the absence of Brønsted acidity in such ZnxZryOz catalysts also eliminates the side isobutene isomerization and undesired polymerization/coke reactions, resulting in the production of high purity isobutene with significantly improved catalyst stability (< 2% activity loss after 200 h time-on-stream). This work not only demonstrates a balanced Lewis acid-base pair for the highly active and selective cascade ethanol-to-isobutene reaction, but also sheds light on the rational design of selective and robust acid-base catalyst for C-C coupling via aldolization reaction.

  3. Direct and converse measurements of electrostriction in low permittivity dielectrics

    NASA Astrophysics Data System (ADS)

    Yimnirun, Rattikorn

    Electrostriction is the basic electromechanical coupling mechanism in all insulators. For most low permittivity dielectrics, the electrostrictive effects are extremely small, and are often obscured by other phenomena, making them difficult to measure. This study presents electrostriction measurements on low permittivity single crystals, ceramics, glasses, glass- ceramics, and polymers by two independent techniques. A single-beam interferometer with the capability of resolving 10-4 Å in the field- induced displacement was used for the direct coefficient measurements. For the converse technique, a dynamic compressometer was constructed to measure stress-induced changes in capacitance as small as 10-17 F. Problems associated with the measurements, along with procedures designed to eliminate or minimize these problems were discussed. To obtain the true electrostrictive coefficients, Maxwell stress and thermal stress corrections are required for the direct method, while a stress-induced geometric correction must be accounted for in the converse measurement. These corrections are found to be very significant in low permittivity dielectrics. Nevertheless, the results from the two methods are, with a few exceptions, in fairly good agreement. This study presents for the first time the electrostrictive coefficients of several important electronic packaging materials including Al2O 3, BeO, MgO, silica glass, and other engineering glass-ceramics and polymers. Most of the low permittivity dielectrics studied have electrostrictive M coefficients between 10-23 to 10-21 m2/V2, far smaller than the M coefficients of 10-16 m2/V2 in relaxor ferroelectrics and 10-18 m2/V2 in very compliant polymers such as polyurethane. All the materials studied exhibit positive longitudinal coefficients, while the transverse coefficients can be either positive or negative. In units of 10-21 m2/V2, the M11 coefficients of common engineering polymers ranged from +0.4 in polystyrene to +12.7 in

  4. 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.

  5. Method for direct conversion of gaseous hydrocarbons to liquids

    DOEpatents

    Kong, Peter C.; Lessing, Paul A.

    2006-03-07

    A chemical reactor for direct conversion of hydrocarbons includes a dielectric barrier discharge plasma cell and a solid oxide electrochemical cell in fluid communication therewith. The discharge plasma cell comprises a pair of electrodes separated by a dielectric material and passageway therebetween. The electrochemical cell comprises a mixed-conducting solid oxide electrolyte membrane tube positioned between a porous cathode and a porous anode, and a gas inlet tube for feeding oxygen containing gas to the porous cathode. An inlet is provided for feeding hydrocarbons to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a light source for directing ultraviolet light into the discharge plasma cell and the electrochemical cell.

  6. Direct energy conversion system for D(3)-He fusion

    NASA Astrophysics Data System (ADS)

    Tomita, Y.; Shu, L. Y.; Momota, H.

    1993-11-01

    A novel and highly efficient direct energy conversion system is proposed for utilizing D(3)-He fueled fusion. In order to convert kinetic energy of ions, we applied a pair of direct energy conversion systems each of which has a cusp-type DEC and a traveling wave DEC (TWDEC). In a cusp-type DEC, electrons are separated from the escaping ions at the first line-cusp and the energy of thermal ion components is converted at the second cusp DEC. The fusion protons go through the cusp-type DEC and arrive at the TWDEC, which principle is similar to 'LINAC'. The energy of fusion protons is recovered to electricity with an efficiency of more than 70%. These DEC's bring about the high efficient fusion plant.

  7. Direct conversion of light hydrocarbon gases to liquid fuel

    SciTech Connect

    Foral, M.J.

    1990-01-01

    The objective of this program is to investigate the direct conversion of light gaseous hydrocarbons, such as those produced during Fischer-Tropsch synthesis or as a product of gasification, to liquid transportation fuels via a partial oxidation process. The process will be tested in an existing pilot plant to obtain credible mass balances. Specific objectives to be met include determination of optimal process conditions, investigation of various processing options (e.g. feed injection, product quench, and recycle systems), and evaluation of the various options will be performed as experimental data become available.

  8. Direct conversion of light hydrocarbon gases to liquid fuel

    SciTech Connect

    Foral, M.J.

    1991-01-01

    The objective of this program is to investigate the direct conversion of light gaseous hydrocarbons, such as those produced during Fischer-Tropsch synthesis or as a product of gasification, to liquid transportation fuels via a partial oxidation process. The process will be tested in an existing pilot plant to obtain credible mass balances. Specific objectives to be met include determination of optimal process conditions, investigation of various processing options (e.g. feed injection, product quench, and recycle systems), and evaluation of an enhanced yield thermal/catalytic system. Economic evaluation of the various options will be performed as experimental data become available.

  9. Direct conversion of light hydrocarbon gases to liquid fuel

    SciTech Connect

    Kaplan, R.D.; Foral, M.J.

    1992-05-16

    Amoco oil Company, has investigated the direct, non-catalytic conversion of light hydrocarbon gases to liquid fuels (particularly methanol) via partial oxidation. The primary hydrocarbon feed used in these studies was natural gas. This report describes work completed in the course of our two-year project. In general we determined that the methanol yields delivered by this system were not high enough to make it economically attractive. Process variables studied included hydrocarbon feed composition, oxygen concentration, temperature and pressure effects, residence time, reactor design, and reactor recycle.

  10. First direct proof of internal conversion between bound states

    NASA Astrophysics Data System (ADS)

    Carreyre, T.; Harston, M. R.; Aiche, M.; Bourgine, F.; Chemin, J. F.; Claverie, G.; Goudour, J. P.; Scheurer, J. N.; Attallah, F.; Bogaert, G.; Kiener, J.; Lefebvre, A.; Durell, J.; Grandin, J. P.; Meyerhof, W. E.; Phillips, W.

    2000-08-01

    We present direct evidence for the process of internal conversion between bound atomic states (BIC) when the binding energy of the converted electron becomes larger than the nuclear transition energy. This process has been proposed as an explanation of the measured, unexpectedly short lifetime of the first excited state of 125Te with charge state larger than 44+. We have detected the Kα x rays emitted in flight which follow the filling of the K-shell vacancy created by the bound internal conversion process, together with γ rays from Te ions in charge states ranging between 44+ and 48+. For Te45+ and Te46+, the comparison of the x-ray to γ-ray ratios with the theoretical calculations of the internal conversion coefficients including decay to bound atomic states, assuming Te ions in their ground electronic state, show poor agreement. The agreement becomes good if account is taken of BIC decay of excited initial states with different occupancies of the 2p1/2 and 2p3/2 subshells. In this situation, the half-life becomes sensitive to the precise initial state and simple specification of the charge state alone is no longer appropriate.

  11. Direct Conversion Technology. Progress report, January 1, 1992--June 30, 1992

    SciTech Connect

    Back, L.H.; Fabris, G.; Ryan, M.A.

    1992-07-01

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. Initially, two systems were selected for exploratory research and advanced development. These are Alkali Metal Thermal-to-Electric Converter (AMTEC) and Two-Phase Liquid Metal MD Generator (LMMHD). This report describes progress that has been made during the first six months of 1992 on research activities associated with these two systems. (GHH)

  12. Direct conversion technology. Annual summary report CY 1991, January 1, 1991--December 31, 1991

    SciTech Connect

    Massier, P.F.; Back, L.H.; Ryan, M.A.; Fabris, G.

    1992-01-07

    The overall objective of the Direct Conversion Technology task is to develop an experimentally verified technology base for promising direct conversion systems that have potential application for energy conservation in the end-use sectors. This report contains progress of research on the Alkali Metal Thermal-to-Electric Converter (AMTEC) and on the Two-Phase Liquid-Metal MHD Electrical Generator (LMMHD) for the period January 1, 1991 through December 31, 1991. Research on AMTEC and on LMMHD was initiated during October 1987. Reports prepared on previous occasions (Refs. 1--5) contain descriptive and performance discussions of the following direct conversion concepts: thermoelectric, pyroelectric, thermionic, thermophotovoltaic, thermoacoustic, thermomagnetic, thermoelastic (Nitionol heat engine); and also, more complete descriptive discussions of AMTEC and LMMHD systems.

  13. Prediction of conversion to psychosis: review and future directions

    PubMed Central

    Gee, Dylan G.; Cannon, Tyrone D.

    2014-01-01

    This article reviews recent findings on predictors of conversion to psychosis among youth deemed at ultra high risk (UHR) based on the presence of subpsychotic-intensity symptoms or genetic risk for psychosis and a recent decline in functioning. Although transition rates differ between studies, the most well powered studies have observed rates of conversion to full psychosis in the 30–40% range over 2–3 years of follow-up. Across studies, severity of subthreshold positive symptoms, poorer social functioning, and genetic risk for schizophrenia appear to be consistent predictors of conversion to psychosis, with algorithms combining these indicators achieving positive predictive power ≥ 80%. Nevertheless, a substantial fraction of UHR cases do not convert to psychosis. Recent work indicates that UHR cases who present with lower levels of negative symptoms and higher levels of social functioning are more likely to recover symptomatically and no longer meet criteria for an at-risk mental state. In general, it appears that about 1/3 of UHR cases convert to psychosis, about 1/3 do not convert but remain symptomatic and functionally impaired, and about 1/3 recover symptomatically and functionally. Continued efforts to detect early risk for psychosis are critical for informing early intervention and provide increasing promise of delaying or even preventing the onset of psychosis. PMID:22286564

  14. Direct conversion of terpenylalkanolamines to ethylidyne N-nitroso compounds

    USGS Publications Warehouse

    Abidi, S.L.

    1986-01-01

    A series of mono- and diterpenylalkanolamines bearing isopropylidene functionality on the terpene group was reacted with sodium nitrite in aqueous acetic acid to yield ethylidyne N-nitroso analogues. The key feature of this direct conversion involved initial N-nitrosation followed by apparent elimination of a "CH4" unit (not necessarily methane) from the isopropylidene double bond. The product distribution data for ethylidyne nitrosamines derived from tertiary terpenyl alkanolamines reflect the conformational outcome of the nitrosative dealkylation process. For β,γ-unsaturated allylic diterpenylethanolamines, electronic effects appeared to be important for controlling the product distribution of ethylidyne nitrosamines in light of the highly selective α-cleavage observed in the nitrosation reactions.

  15. Direct conversion of light hydrocarbon gases to liquid fuel

    SciTech Connect

    Foral, M.J.

    1990-01-01

    Amoco Oil Company is investigating the direct conversion of light hydrocarbon gases to liquid fuels via partial oxidation. This report describes work completed in the first quarter of the two-year project (first quarter FY 1990). Task 1 of the work, preparation of the Project Management Plan, has been completed. Work was started and progress made on three other tasks during this quarter: Task 2. Modification of an existing Amoco pilot plant to handle the conditions of this project. Minor modifications were made to increase the maximum operating pressure to 1500 psig. Other more extensive modifications are being designed, including addition of an oxygen compressor and recycle system. Task 3.1. Evaluation of a Los Alamos National Laboratory methane oxidation kinetic model for suitability in guiding the experimental portions of this project. Task 3.2. Process variable (e.g. temperature, pressure, residence time) studies to determine optimal partial oxidation conditions. 1 fig.

  16. Direct catalytic conversion of synthesis gas to lower olefins

    SciTech Connect

    Janardanarao, M. )

    1990-09-01

    Direct conversion of synthesis gas to lower olefins has been considered as a possible solution to meet the growing demand for chemical feedstocks such as ethylene, propylene, and butylenes. This review covers the various catalyst systems and operating conditions that have been used in meeting this objective. Though the product distribution in Fischer--Tropsch synthesis is governed by the existence of an Anderson--Schultz--Flory polymerization model, certain modifications in the catalyst formulations have produced a shift toward lower molecular weight olefins. At the present time, the yields and selectivities of lower olefins are far from optimal, but continued research efforts in this area may lead to the development of stable catalyst systems capable of producing highly desirable distributions of lower olefins.

  17. Direct fission fragment energy conversion utilizing magnetic collimation

    NASA Astrophysics Data System (ADS)

    Tsvetkov, Pavel Valeryevich

    The objective of this dissertation was to determine the technological feasibility of direct fission fragment energy conversion utilizing magnetic collimation (DFFEC-MC). This objective was accomplished by producing a conceptual design for a DFFEC-MC system and by analysis of the potential DFFEC-MC system performance. Consistent analysis and evaluation of the technological feasibility of the DFFEC-MC concept were achieved using state-of-the-art computer codes that allowed realistic and consistent modeling of the important physical processes governing DFFEC-MC system performance. Unique computational schemes, including three-dimensional modeling, were constructed and applied to obtain the performance characteristics of DFFEC-MC systems. Special effort was made to include all important physical processes. Important simplifications introduced due to modeling limitations were also assessed. The analysis takes into consideration a wide range of operational aspects including fission fragment (FF) escape from the fuel, FF collimation, FF collection, criticality, long-term performance, energy conversion efficiency, heat removal, and safety characteristics. Required engineering conditions are formulated that must be satisfied in order for the DFFEC-MC concept to have a reasonable chance to demonstrate technological feasibility. Specific characteristics of individual system components and the entire DFFEC-MC system are evaluated. To identify which technological improvements are needed, several possible design solutions are provided for some of the components along with analyses of the corresponding DFFEC-MC system performance. As a result of the computational analysis, the conditions for achieving an attractive (high) system efficiency are demonstrated. A technologically feasible DFFEC-MC system layout with promising operational characteristics is presented. The resulting DFFEC-MC system is envisioned as an advanced DFFEC system that combines advantageous design solutions

  18. Hangout with CERN: a direct conversation with the public

    NASA Astrophysics Data System (ADS)

    Rao, Achintya; Goldfarb, Steven; Kahle, Kate

    2016-04-01

    Hangout with CERN refers to a weekly, half-hour-long, topical webcast hosted at CERN. The aim of the programme is threefold: (i) to provide a virtual tour of various locations and facilities at CERN, (ii) to discuss the latest scientific results from the laboratory, and, most importantly, (iii) to engage in conversation with the public and answer their questions. For each ;episode;, scientists gather around webcam-enabled computers at CERN and partner institutes/universities, connecting to one another using the Google+ social network's ;Hangouts; tool. The show is structured as a conversation mediated by a host, usually a scientist, and viewers can ask questions to the experts in real time through a Twitter hashtag or YouTube comments. The history of Hangout with CERN can be traced back to ICHEP 2012, where several physicists crowded in front of a laptop connected to Google+, using a ;Hangout On Air; webcast to explain to the world the importance of the discovery of the Higgs-like boson, announced just two days before at the same conference. Hangout with CERN has also drawn inspiration from two existing outreach endeavours: (i) ATLAS Virtual Visits, which connected remote visitors with scientists in the ATLAS Control Room via video conference, and (ii) the Large Hangout Collider, in which CMS scientists gave underground tours via Hangouts to groups of schools and members of the public around the world. In this paper, we discuss the role of Hangout with CERN as a bi-directional outreach medium and an opportunity to train scientists in effective communication.

  19. Carbon dioxide conversion over carbon-based nanocatalysts.

    PubMed

    Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

    2013-07-01

    The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.

  20. Direct Energy Conversion for Nuclear Propulsion at Low Specific Mass

    NASA Technical Reports Server (NTRS)

    Scott, John H.

    2014-01-01

    The project will continue the FY13 JSC IR&D (October-2012 to September-2013) effort in Travelling Wave Direct Energy Conversion (TWDEC) in order to demonstrate its potential as the core of a high potential, game-changing, in-space propulsion technology. The TWDEC concept converts particle beam energy into radio frequency (RF) alternating current electrical power, such as can be used to heat the propellant in a plasma thruster. In a more advanced concept (explored in the Phase 1 NIAC project), the TWDEC could also be utilized to condition the particle beam such that it may transfer directed kinetic energy to a target propellant plasma for the purpose of increasing thrust and optimizing the specific impulse. The overall scope of the FY13 first-year effort was to build on both the 2012 Phase 1 NIAC research and the analysis and test results produced by Japanese researchers over the past twenty years to assess the potential for spacecraft propulsion applications. The primary objective of the FY13 effort was to create particle-in-cell computer simulations of a TWDEC. Other objectives included construction of a breadboard TWDEC test article, preliminary test calibration of the simulations, and construction of first order power system models to feed into mission architecture analyses with COPERNICUS tools. Due to funding cuts resulting from the FY13 sequestration, only the computer simulations and assembly of the breadboard test article were completed. The simulations, however, are of unprecedented flexibility and precision and were presented at the 2013 AIAA Joint Propulsion Conference. Also, the assembled test article will provide an ion current density two orders of magnitude above that available in previous Japanese experiments, thus enabling the first direct measurements of power generation from a TWDEC for FY14. The proposed FY14 effort will use the test article for experimental validation of the computer simulations and thus complete to a greater fidelity the

  1. Direct electrochemical conversion of carbon anode fuels in molton salt media

    SciTech Connect

    Cherepy, N; Krueger, R; Cooper, J F

    2001-01-17

    We are conducting research into the direct electrochemical conversion of reactive carbons into electricity--with experimental evidence of total efficiencies exceeding 80% of the heat of combustion of carbon. Together with technologies for extraction of reactive carbons from broad based fossil fuels, direct carbon conversion addresses the objectives of DOE's ''21st Century Fuel Cell'' with exceptionally high efficiency (>70% based on standard heat of reaction, {Delta}H{sub std}), as well as broader objectives of managing CO{sub 2} emissions. We are exploring the reactivity of a wide range of carbons derived from diverse sources, including pyrolyzed hydrocarbons, petroleum cokes, purified coals and biochars, and relating their electrochemical reactivity to nano/microstructural characteristics.

  2. Conversation Intention Perception based on Knowledge Base

    DTIC Science & Technology

    2014-05-01

    Yi Liu Gastritis Fracture Vomit Pain Bleeding thirst Anti-acid Clarithromycin styptic Aspirin Symptom Medicine Disease 1/117 1/157 1/20...occurrence frequency. Firstly, we compute the distance between two entities. For example, distance between entity Gastritis and entity Vomit is...considered as one as they are connected directly, distance between entity Gastritis and entity Fracture is two since they are con- nected through entity

  3. Direct observation of up-conversion via femtosecond photoelectron imaging

    NASA Astrophysics Data System (ADS)

    Liu, Yuzhu; Knopp, Gregor; Gerber, Thomas

    2015-10-01

    Ultrafast relaxation dynamics in 2-methylfuran has been investigated by time-resolved photoelectron imaging. An "up" internal conversion from a low-lying state into a higher-lying one has been observed experimentally. Temporal photoelectron kinetic-energy distributions and angular distributions of the photoelectrons are analyzed. In the up-conversion process, the vibrational energy in the initial state is converted to the electronic energy of the final state during the energy transfer. And the time scale for the up-conversion process is estimated by the observed onset delay for the corresponding photoelectron bands.

  4. Direct conversion semiconductor detectors in positron emission tomography

    NASA Astrophysics Data System (ADS)

    Cates, Joshua W.; Gu, Yi; Levin, Craig S.

    2015-05-01

    Semiconductor detectors are playing an increasing role in ongoing research to improve image resolution, contrast, and quantitative accuracy in preclinical applications of positron emission tomography (PET). These detectors serve as a medium for direct detection of annihilation photons. Early clinical translation of this technology has shown improvements in image quality and tumor delineation for head and neck cancers, relative to conventional scintillator-based systems. After a brief outline of the basics of PET imaging and the physical detection mechanisms for semiconductor detectors, an overview of ongoing detector development work is presented. The capabilities of semiconductor-based PET systems and the current state of these devices are discussed.

  5. Caring, Conversing, and Realizing Values: New Directions in Language Studies

    ERIC Educational Resources Information Center

    Hodges, Bert H.; Steffensen, Sune V.; Martin, James E.

    2012-01-01

    Language serves many functions for humans, but three of the most important are coordination, learning, and friendship. All of those functions were well served by the conversations from which this special issue emerged, a conference, "Grounding language in perception and (inter) action", held at Gordon College in June 2009. The conference brought…

  6. Caring, Conversing, and Realizing Values: New Directions in Language Studies

    ERIC Educational Resources Information Center

    Hodges, Bert H.; Steffensen, Sune V.; Martin, James E.

    2012-01-01

    Language serves many functions for humans, but three of the most important are coordination, learning, and friendship. All of those functions were well served by the conversations from which this special issue emerged, a conference, "Grounding language in perception and (inter) action", held at Gordon College in June 2009. The conference brought…

  7. Thermoelectric Energy Conversion: Future Directions and Technology Development Needs

    NASA Technical Reports Server (NTRS)

    Fleurial, Jean-Pierre

    2007-01-01

    This viewgraph presentation reviews the process of thermoelectric energy conversion along with key technology needs and challenges. The topics include: 1) The Case for Thermoelectrics; 2) Advances in Thermoelectrics: Investment Needed; 3) Current U.S. Investment (FY07); 4) Increasing Thermoelectric Materials Conversion Efficiency Key Science Needs and Challenges; 5) Developing Advanced TE Components & Systems Key Technology Needs and Challenges; 6) Thermoelectrics; 7) 200W Class Lightweight Portable Thermoelectric Generator; 8) Hybrid Absorption Cooling/TE Power Cogeneration System; 9) Major Opportunities in Energy Industry; 10) Automobile Waste Heat Recovery; 11) Thermoelectrics at JPL; 12) Recent Advances at JPL in Thermoelectric Converter Component Technologies; 13) Thermoelectrics Background on Power Generation and Cooling Operational Modes; 14) Thermoelectric Power Generation; and 15) Thermoelectric Cooling.

  8. Thermoelectric Energy Conversion: Future Directions and Technology Development Needs

    NASA Technical Reports Server (NTRS)

    Fleurial, Jean-Pierre

    2007-01-01

    This viewgraph presentation reviews the process of thermoelectric energy conversion along with key technology needs and challenges. The topics include: 1) The Case for Thermoelectrics; 2) Advances in Thermoelectrics: Investment Needed; 3) Current U.S. Investment (FY07); 4) Increasing Thermoelectric Materials Conversion Efficiency Key Science Needs and Challenges; 5) Developing Advanced TE Components & Systems Key Technology Needs and Challenges; 6) Thermoelectrics; 7) 200W Class Lightweight Portable Thermoelectric Generator; 8) Hybrid Absorption Cooling/TE Power Cogeneration System; 9) Major Opportunities in Energy Industry; 10) Automobile Waste Heat Recovery; 11) Thermoelectrics at JPL; 12) Recent Advances at JPL in Thermoelectric Converter Component Technologies; 13) Thermoelectrics Background on Power Generation and Cooling Operational Modes; 14) Thermoelectric Power Generation; and 15) Thermoelectric Cooling.

  9. 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.

  10. Direct conversion of methane to aromatics in a catalytic co-ionic membrane reactor.

    PubMed

    Morejudo, S H; Zanón, R; Escolástico, S; Yuste-Tirados, I; Malerød-Fjeld, H; Vestre, P K; Coors, W G; Martínez, A; Norby, T; Serra, J M; Kjølseth, C

    2016-08-05

    Nonoxidative methane dehydroaromatization (MDA: 6CH4 ↔ C6H6 + 9H2) using shape-selective Mo/zeolite catalysts is a key technology for exploitation of stranded natural gas reserves by direct conversion into transportable liquids. However, this reaction faces two major issues: The one-pass conversion is limited by thermodynamics, and the catalyst deactivates quickly through kinetically favored formation of coke. We show that integration of an electrochemical BaZrO3-based membrane exhibiting both proton and oxide ion conductivity into an MDA reactor gives rise to high aromatic yields and improved catalyst stability. These effects originate from the simultaneous extraction of hydrogen and distributed injection of oxide ions along the reactor length. Further, we demonstrate that the electrochemical co-ionic membrane reactor enables high carbon efficiencies (up to 80%) that improve the technoeconomic process viability. Copyright © 2016, American Association for the Advancement of Science.

  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. A Review of Previous Research in Direct Energy Conversion Fission Reactors

    SciTech Connect

    DUONG,HENRY; POLANSKY,GARY F.; SANDERS,THOMAS L.; SIEGEL,MALCOLM D.

    1999-09-22

    From the earliest days of power reactor development, direct energy conversion was an obvious choice to produce high efficiency electric power generation. Directly capturing the energy of the fission fragments produced during nuclear fission avoids the intermediate conversion to thermal energy and the efficiency limitations of classical thermodynamics. Efficiencies of more than 80% are possible, independent of operational temperature. Direct energy conversion fission reactors would possess a number of unique characteristics that would make them very attractive for commercial power generation. These reactors would be modular in design with integral power conversion and operate at low pressures and temperatures. They would operate at high efficiency and produce power well suited for long distance transmission. They would feature large safety margins and passively safe design. Ideally suited to production by advanced manufacturing techniques, direct energy conversion fission reactors could be produced more economically than conventional reactor designs. The history of direct energy conversion can be considered as dating back to 1913 when Moseleyl demonstrated that charged particle emission could be used to buildup a voltage. Soon after the successful operation of a nuclear reactor, E.P. Wigner suggested the use of fission fragments for direct energy conversion. Over a decade after Wigner's suggestion, the first theoretical treatment of the conversion of fission fragment kinetic energy into electrical potential appeared in the literature. Over the ten years that followed, a number of researchers investigated various aspects of fission fragment direct energy conversion. Experiments were performed that validated the basic physics of the concept, but a variety of technical challenges limited the efficiencies that were achieved. Most research in direct energy conversion ceased in the US by the late 1960s. Sporadic interest in the concept appears in the literature until this

  14. Polymer Based Nanocomposites for Solar Energy Conversion

    SciTech Connect

    Shaheen, S.; Olson, D.; White, M.; Mitchell, W.; Miedaner, A.; Curtis, C.; Rumbles, G.; Gregg, B.; Ginley, D.

    2005-01-01

    Organic semiconductor-based photovoltaic devices offer the promise of low cost photovoltaic technology that can be manufactured via large-scale, roll-to-roll printing techniques. Existing organic photovoltaic devices are currently limited to solar power conversion efficiencies of 3?5%. This is because of poor overlap between the absorption spectrum of the organic chromophores and the solar spectrum, non-ideal band alignment between the donor and acceptor species, and low charge carrier mobilities. To address these issues, we are investigating the development of dendrimeric organic semiconductors that are readily synthesized with high purity. They also benefit from optoelectronic properties, such as band gap and band positions, which can be easily tuned by substituting different chemical groups into the molecule. Additionally, we are developing nanostructured oxide/conjugated polymer composite photovoltaics. These composites take advantage of the high electron mobilities attainable in oxide semiconductors and can be fabricated using low-temperature solution-based growth techniques. Here, we discuss the synthesis and preliminary device results of these novel materials and composites.

  15. Direct-conversion flat-panel x-ray imaging: reduction of noise by presampling filtration

    NASA Astrophysics Data System (ADS)

    Rowlands, John A.; Ji, Winston G.; Zhao, Wei; Lee, Denny L. Y.

    2000-04-01

    Large area flat panel solid-state detectors are being studied for digital radiography and fluoroscopy. Such systems use active matrix arrays to readout latent charge images created either by direct conversion of x-ray energy to charge in a photoconductor or indirectly using a phosphor and individual photodiodes on the active matrix array. Our work has utilized the direct conversion method because of its simplicity and the higher resolution possible due to the electrostatic collection of secondary quanta. Aliasing of noise occurs in current designs of direct detectors based on amorphous selenium ((alpha) -Se) because of its high intrinsic resolution. This aliasing leads to a decrease in detective quantum efficiency (DQE) as frequency increases. It has been predicted, using a previously developed model of the complete imaging system, that appropriately controlled spatial filtration can reduce this aliased noise and hence increase DQE at the Nyquist frequency, fNY. Our purpose is to experimentally verify this concept by implementing presampling filtration in a practical flat panel system. An (alpha) -Se based flat panel imager is modified by incorporating an insulating layer between the active matrix and the (alpha) -Se layer to introduce a predetermined amount of presampling burring. The modified imager is evaluated using standard linear analysis tools, modulation transfer function (MTF), noise power spectra (NPS) and DQE(f), and the results are compared to theoretical predictions.

  16. Direct nitrogen fixation at the edges of graphene nanoplatelets as efficient electrocatalysts for energy conversion

    PubMed Central

    Jeon, In-Yup; Choi, Hyun-Jung; Ju, Myung Jong; Choi, In Taek; Lim, Kimin; Ko, Jaejung; Kim, Hwan Kyu; Kim, Jae Cheon; Lee, Jae-Joon; Shin, Dongbin; Jung, Sun-Min; Seo, Jeong-Min; Kim, Min-Jung; Park, Noejung; Dai, Liming; Baek, Jong-Beom

    2013-01-01

    Nitrogen fixation is essential for the synthesis of many important chemicals (e.g., fertilizers, explosives) and basic building blocks for all forms of life (e.g., nucleotides for DNA and RNA, amino acids for proteins). However, direct nitrogen fixation is challenging as nitrogen (N2) does not easily react with other chemicals. By dry ball-milling graphite with N2, we have discovered a simple, but versatile, scalable and eco-friendly, approach to direct fixation of N2 at the edges of graphene nanoplatelets (GnPs). The mechanochemical cracking of graphitic C−C bonds generated active carbon species that react directly with N2 to form five- and six-membered aromatic rings at the broken edges, leading to solution-processable edge-nitrogenated graphene nanoplatelets (NGnPs) with superb catalytic performance in both dye-sensitized solar cells and fuel cells to replace conventional Pt-based catalysts for energy conversion. PMID:23877200

  17. Direct nitrogen fixation at the edges of graphene nanoplatelets as efficient electrocatalysts for energy conversion

    NASA Astrophysics Data System (ADS)

    Jeon, In-Yup; Choi, Hyun-Jung; Ju, Myung Jong; Choi, In Taek; Lim, Kimin; Ko, Jaejung; Kim, Hwan Kyu; Kim, Jae Cheon; Lee, Jae-Joon; Shin, Dongbin; Jung, Sun-Min; Seo, Jeong-Min; Kim, Min-Jung; Park, Noejung; Dai, Liming; Baek, Jong-Beom

    2013-07-01

    Nitrogen fixation is essential for the synthesis of many important chemicals (e.g., fertilizers, explosives) and basic building blocks for all forms of life (e.g., nucleotides for DNA and RNA, amino acids for proteins). However, direct nitrogen fixation is challenging as nitrogen (N2) does not easily react with other chemicals. By dry ball-milling graphite with N2, we have discovered a simple, but versatile, scalable and eco-friendly, approach to direct fixation of N2 at the edges of graphene nanoplatelets (GnPs). The mechanochemical cracking of graphitic C-C bonds generated active carbon species that react directly with N2 to form five- and six-membered aromatic rings at the broken edges, leading to solution-processable edge-nitrogenated graphene nanoplatelets (NGnPs) with superb catalytic performance in both dye-sensitized solar cells and fuel cells to replace conventional Pt-based catalysts for energy conversion.

  18. DIRECT ENERGY CONVERSION (DEC) FISSION REACTORS - A U.S. NERI PROJECT

    SciTech Connect

    D. BELLER; G. POLANSKY; ET AL

    2000-11-01

    The direct conversion of the electrical energy of charged fission fragments was examined early in the nuclear reactor era, and the first theoretical treatment appeared in the literature in 1957. Most of the experiments conducted during the next ten years to investigate fission fragment direct energy conversion (DEC) were for understanding the nature and control of the charged particles. These experiments verified fundamental physics and identified a number of specific problem areas, but also demonstrated a number of technical challenges that limited DEC performance. Because DEC was insufficient for practical applications, by the late 1960s most R&D ceased in the US. Sporadic interest in the concept appears in the literature until this day, but there have been no recent programs to develop the technology. This has changed with the Nuclear Energy Research Initiative that was funded by the U.S. Congress in 1999. Most of the previous concepts were based on a fission electric cell known as a triode, where a central cathode is coated with a thin layer of nuclear fuel. A fission fragment that leaves the cathode with high kinetic energy and a large positive charge is decelerated as it approaches the anode by a charge differential of several million volts, it then deposits its charge in the anode after its kinetic energy is exhausted. Large numbers of low energy electrons leave the cathode with each fission fragment; they are suppressed by negatively biased on grid wires or by magnetic fields. Other concepts include magnetic collimators and quasi-direct magnetohydrodynamic generation (steady flow or pulsed). We present the basic principles of DEC fission reactors, review the previous research, discuss problem areas in detail and identify technological developments of the last 30 years relevant to overcoming these obstacles. A prognosis for future development of direct energy conversion fission reactors will be presented.

  19. Small molecules increase direct neural conversion of human fibroblasts

    PubMed Central

    Pfisterer, Ulrich; Ek, Fredrik; Lang, Stefan; Soneji, Shamit; Olsson, Roger; Parmar, Malin

    2016-01-01

    The generation of human induced neurons (hiNs) via exogenous delivery of neural transcription factors represents a novel technique to obtain disease and patient specific neurons. These cells have the potential to be used for disease modeling, diagnostics and drug screening, and also to be further developed for brain repair. In the present study, we utilized hiNs to develop an unbiased screening assay for small molecules that increase the conversion efficiency. Using this assay, we screened 307 compounds from five annotated libraries and identified six compounds that were very potent in potentiating the reprogramming process. When combined in an optimal combination and dose, these compounds increased the reprogramming efficiency of human fibroblasts more than 6-fold. Global gene expression and CellNet analysis at different timepoints during the reprogramming process revealed that neuron-specific genes and gene regulatory networks (GRNs) became progressively more activated while converting cells shut down fibroblast-specific GRNs. Further bioinformatics analysis revealed that the addition of the six compound resulted in the accelerated upregulation of a subset of neuronal genes, and also increased expression of genes associated with transcriptional activity and mediation of cellular stress response. PMID:27917895

  20. Non-viral approaches for direct conversion into mesenchymal cell types: Potential application in tissue engineering.

    PubMed

    Lee, Eun-Seo; Kim, Seung Hyun L; Lee, Hwajin; Hwang, Nathaniel S

    2016-05-01

    Acquiring adequate number of cells is one of the crucial factors to apply tissue engineering strategies in order to recover critical-sized defects. While the reprogramming technology used for inducing pluripotent stem cells (iPSCs) opened up a direct path for generating pluripotent stem cells, a direct conversion strategy may provide another possibility to obtain desired cells for tissue engineering. In order to convert a somatic cell into any other cell type, diverse approaches have been investigated. Conspicuously, in contrast to traditional viral transduction method, non-viral delivery of conversion factors has the merit of lowering immune responses and provides safer genetic manipulation, thus revolutionizing the generation of directly converted cells and its application in therapeutics. In addition, applying various microenvironmental modulations have potential to ameliorate the conversion of somatic cells into different lineages. In this review, we discuss the recent progress in direct conversion technologies, specifically focusing on generating mesenchymal cell types. © 2016 Wiley Periodicals, Inc.

  1. Turbostar: an ICF reactor using both direct and thermal power conversion. Revision 1

    SciTech Connect

    Pitts, J.H.

    1986-07-31

    Combining direct and thermal power conversion results in a 52% gross plant efficiency with DT fuel and 68% with advanced DD fuel. We maximize the fraction of fusion-yield energy converted to kinetic energy in a liquid-lithium blanket, and use this energy directly with turbine generators to produce electricity. We use the remainder of the energy to produce electricity in a standard Rankine thermal power conversion cycle.

  2. Feasibility of Traveling Wave Direct Energy Conversion of Fission Reaction Fragments

    NASA Technical Reports Server (NTRS)

    Tarditi, A. G.; George, J. A.; Miley, G. H.; Scott, J. H.

    2013-01-01

    Fission fragment direct energy conversion has been considered in the past for the purpose of increasing nuclear power plant efficiency and for advanced space propulsion. Since the fragments carry electric charge (typically in the order of 20 e) and have 100 MeV-range kinetic energy, techniques utilizing very high-voltage DC electrodes have been considered. This study is focused on a different approach: the kinetic energy of the charged fission fragments is converted into alternating current by means of a traveling wave coupling scheme (Traveling Wave Direct Energy Converter, TWDEC), thereby not requiring the utilization of high voltage technology. A preliminary feasibility analysis of the concept is introduced based on a conceptual level study and on a particle simulation model of the beam dynamics.

  3. Direct Conversion of Perovskite Thin Films into Nanowires with Kinetic Control for Flexible Optoelectronic Devices.

    PubMed

    Zhu, Pengchen; Gu, Shuai; Shen, Xinpeng; Xu, Ning; Tan, Yingling; Zhuang, Shendong; Deng, Yu; Lu, Zhenda; Wang, Zhenlin; Zhu, Jia

    2016-02-10

    With significant progress in the past decade, semiconductor nanowires have demonstrated unique features compared to their thin film counterparts, such as enhanced light absorption, mechanical integrity and reduced therma conductivity, etc. However, technologies of semiconductor thin film still serve as foundations of several major industries, such as electronics, displays, energy, etc. A direct path to convert thin film to nanowires can build a bridge between these two and therefore facilitate the large-scale applications of nanowires. Here, we demonstrate that methylammonium lead iodide (CH3NH3PbI3) nanowires can be synthesized directly from perovskite film by a scalable conversion process. In addition, with fine kinetic control, morphologies, and diameters of these nanowires can be well-controlled. Based on these perovskite nanowires with excellent optical trapping and mechanical properties, flexible photodetectors with good sensitivity are demonstrated.

  4. Direct adaptive control of wind energy conversion systems using Gaussian networks.

    PubMed

    Mayosky, M A; Cancelo, I E

    1999-01-01

    Grid connected wind energy conversion systems (WECS) present interesting control demands, due to the intrinsic nonlinear characteristics of windmills and electric generators. In this paper a direct adaptive control strategy for WECS control is proposed. It is based on the combination of two control actions: a radial basis zfunction network-based adaptive controller, which drives the tracking error to zero with user specified dynamics, and a supervisory controller, based on crude bounds of the system's nonlinearities. The supervisory controller fires when the finite neural-network approximation properties cannot be guaranteed. The form of the supervisor control and the adaptation law for the neural controller are derived from a Lyapunov analysis of stability. The results are applied to a typical turbine/generator pair, showing the feasibility of the proposed solution.

  5. Direct measurement of electron beam quality conversion factors using water calorimetry.

    PubMed

    Renaud, James; Sarfehnia, Arman; Marchant, Kristin; McEwen, Malcolm; Ross, Carl; Seuntjens, Jan

    2015-11-01

    In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9-20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%-0.40%) and its influence on the perturbation correction (Type B, 0.10%-0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, kecal, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM's TG-51 protocol. General agreement between the relative

  6. Direct measurement of electron beam quality conversion factors using water calorimetry

    SciTech Connect

    Renaud, James Seuntjens, Jan; Sarfehnia, Arman; Marchant, Kristin; McEwen, Malcolm; Ross, Carl

    2015-11-15

    Purpose: In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. Methods: A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. Results: The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9–20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%–0.40%) and its influence on the perturbation correction (Type B, 0.10%–0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, k{sub ecal}, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM’s TG-51 protocol

  7. Study on the Feasibility of Direct Fusion Energy Conversion for Deep-Space Propulsion

    NASA Astrophysics Data System (ADS)

    Tarditi, Alfonso G.; Miley, George H.; Scott, John H.

    2012-10-01

    A significant change in the current space mission capabilities can be achieved with a highly efficient integration of a fusion energy source with an advanced space propulsion thruster, both with low specific mass. With aneutronic nuclear fusion as the high-density primary energy source, this study considers first electric energy extraction from the fusion reaction products via direct energy conversion to recirculate power as required for the operation of the fusion core. Then the beam of remaining reaction products is conditioned to achieve the optimal thrust and specific impulse for the mission. The research is specifically focused on two key issues: (i) Efficiency improvement of a Traveling Wave Direct Energy Converter (TWDEC, [1]) by achieving a higher ion beam density and optimization of the electrode coupling and of the neutralizing electron flow. (ii) A fast-particle kinetic energy-to-thrust conversion process based on collective interaction between ion bunches well separated in space [2]. Computer simulation results and a design for a basic physics experiment currently under development are reported. [4pt] [1] H. Momota et al., Fus. Tech., 35, 60(1999)[0pt] [2] A. G. Tarditi et al. Proc. NETS 2012 Conf., Woodlands, TX (2012)

  8. Direct Conversion of Methane to Methanol under Mild Conditions over Cu-Zeolites and beyond.

    PubMed

    Tomkins, Patrick; Ranocchiari, Marco; van Bokhoven, Jeroen A

    2017-02-21

    In the recent years methane has become increasingly abundant. However, transportation costs are high and methane recovered as side product is often flared rather than valorized. The chemical utilization of methane is highly challenging and currently mainly based on the cost-intensive production of synthesis gas and its conversion. Alternative routes have been discovered in academia, though high temperatures are mostly required. However, the direct conversion of methane to methanol is an exception. It can already be carried out at comparably low temperatures. It is challenging that methanol is more prone to oxidation than methane, which makes high selectivities at moderate conversions difficult to reach. Decades of research for the direct reaction of methane and oxygen did not yield a satisfactory solution for the direct partial oxidation toward methanol. When changing the oxidant from oxygen to hydrogen peroxide, high selectivities can be reached at rather low conversions, but the cost of hydrogen peroxide is comparably high. However, major advancements in the field were introduced by converting methane to a more stable methanol precursor. Most notable is the conversion of methane to methyl bisulfate in the presence of a platinum catalyst. The reaction is carried out in 102% sulfuric acid using SO3 as the oxidant. This allows for oxidation of the platinum catalyst and prevents the in situ hydrolysis of methyl bisulfate toward the less stable methanol. With a slightly different motif, the stepped conversion of methane to methanol over copper-zeolites was developed a decade ago. The copper-zeolite is first activated in oxygen at 450 °C, and then cooled to 200 °C and reacts with methane in the absence of oxygen, thus protecting a methanol precursor from overoxidation. Subsequently methanol can be extracted with water. Several active copper-zeolites were found, and the active sites were identified and discussed. For a long time, the process was almost unchanged

  9. Direct Carbon Conversion: Review of Production and Electrochemical Conversion of Reactive Carbons, Economics and Potential Impact on the Carbon Cycle

    SciTech Connect

    Cooper, J F; Cherepy, N; Upadhye, R; Pasternak, A; Steinberg, M

    2000-12-12

    Concerns over global warning have motivated the search for more efficient technologies for electric power generation from fossil fuels. Today, 90% of electric power is produced from coal, petroleum or natural gas. Higher efficiency reduces the carbon dioxide emissions per unit of electric energy. Exercising an option of deep geologic or ocean sequestration for the CO{sub 2} byproduct would reduce emissions further and partially forestall global warming. We introduce an innovative concept for conversion of fossil fuels to electricity at efficiencies in the range of 70-85% (based on standard enthalpy of the combustion reaction). These levels exceed the performance of common utility plants by up to a factor of two. These levels are also in excess of the efficiencies of combined cycle plants and of advanced fuel cells now operated on the pilot scale. The core of the concept is direct carbon conversion a process that is similar to that a fuel cell but differs in that synthesized forms of carbon, not hydrogen, are used as fuel. The cell sustains the reaction, C + O{sub 2} = CO{sub 2} (E {approx} 1.0 V, T = 800 C). The fuel is in the form of fine particulates ({approx}100 nm) distributed by entrainment in a flow of CO{sub 2} to the cells to form a slurry of carbon in the melt. The byproduct stream of CO{sub 2} is pure. It affords the option of sequestration without additional separation costs, or can be reused in secondary oil or gas recovery. Our experimental program has discovered carbon materials with orders of magnitude spreads in anode reactivity reflected in cell power density. One class of materials yields energy at about 1 kW/m{sup 2} sufficiently high to make practical the use of the cell in electric utility applications. The carbons used in such cells are highly disordered on the nanometer scale (2-30 nm), relative to graphite. Such disordered or turbostratic carbons can be produced by controlled pyrolysis (thermal decomposition) of hydrocarbons extracted from

  10. Direct Solid-State Conversion of Recyclable Metals and Alloys

    SciTech Connect

    Kiran Manchiraju

    2012-03-27

    Friction Stir Extrusion (FSE) is a novel energy-efficient solid-state material synthesis and recycling technology capable of producing large quantity of bulk nano-engineered materials with tailored, mechanical, and physical properties. The novelty of FSE is that it utilizes the frictional heating and extensive plastic deformation inherent to the process to stir, consolidate, mechanically alloy, and convert the powders, chips, and other recyclable feedstock materials directly into useable product forms of highly engineered materials in a single step (see Figure 1). Fundamentally, FSE shares the same deformation and metallurgical bonding principles as in the revolutionary friction stir welding process. Being a solid-state process, FSE eliminates the energy intensive melting and solidification steps, which are necessary in the conventional metal synthesis processes. Therefore, FSE is highly energy-efficient, practically zero emissions, and economically competitive. It represents a potentially transformational and pervasive sustainable manufacturing technology for metal recycling and synthesis. The goal of this project was to develop the technological basis and demonstrate the commercial viability of FSE technology to produce the next generation highly functional electric cables for electricity delivery infrastructure (a multi-billion dollar market). Specific focus of this project was to (1) establish the process and material parameters to synthesize novel alloys such as nano-engineered materials with enhanced mechanical, physical, and/or functional properties through the unique mechanical alloying capability of FSE, (2) verifying the expected major energy, environmental, and economic benefits of FSE technology for both the early stage 'showcase' electric cable market and the anticipated pervasive future multi-market applications across several industry sectors and material systems for metal recycling and sustainable manufacturing.

  11. Hot Carrier-Based Near-Field Thermophotovoltaic Energy Conversion.

    PubMed

    St-Gelais, Raphael; Bhatt, Gaurang Ravindra; Zhu, Linxiao; Fan, Shanhui; Lipson, Michal

    2017-03-28

    Near-field thermophotovoltaics (NFTPV) is a promising approach for direct conversion of heat to electrical power. This technology relies on the drastic enhancement of radiative heat transfer (compared to conventional blackbody radiation) that occurs when objects at different temperatures are brought to deep subwavelength distances (typically <100 nm) from each other. Achieving such radiative heat transfer between a hot object and a photovoltaic (PV) cell could allow direct conversion of heat to electricity with a greater efficiency than using current solid-state technologies (e.g., thermoelectric generators). One of the main challenges in the development of this technology, however, is its incompatibility with conventional silicon PV cells. Thermal radiation is weak at frequencies larger than the ∼1.1 eV bandgap of silicon, such that PV cells with lower excitation energies (typically 0.4-0.6 eV) are required for NFTPV. Using low bandgap III-V semiconductors to circumvent this limitation, as proposed in most theoretical works, is challenging and therefore has never been achieved experimentally. In this work, we show that hot carrier PV cells based on Schottky junctions between silicon and metallic films could provide an attractive solution for achieving high efficiency NFTPV electricity generation. Hot carrier science is currently an important field of research and several approaches are investigated for increasing the quantum efficiency (QE) of hot carrier generation beyond conventional Fowler model predictions. If the Fowler limit can indeed be overcome, we show that hot carrier-based NFTPV systems-after optimization of their thermal radiation spectrum-could allow electricity generation with up to 10-30% conversion efficiencies and 10-500 W/cm(2) generated power densities (at 900-1500 K temperatures). We also discuss how the unique properties of thermal radiation in the extreme near-field are especially well suited for investigating recently proposed approaches

  12. Conversational Awareness in Text-Based Computer Mediated Communication

    NASA Astrophysics Data System (ADS)

    Tran, Minh Hong; Yang, Yun; Raikundalia, Gitesh K.

    Text-based computer-mediated communication (TxtCMC) supports an instant exchange of messages among geographically distributed people. TxtCMC, such as Instant Messaging and chat tools, has increasingly become widespread and popular at home and at work. Supporting conversational awareness is an important aspect of TxtCMC. Conversational awareness provides a user with information about the presence and activity of others, and therefore helps to establish a context for the user’s own activity. Unfortunately, current interface design of TxtCMC provides inadequate support for conversational awareness, especially in support for awareness of turn-taking, conversational context and multiple concurrent conversations. This research aims to address these three issues by (1) conducting an empirical study to identify the user need for conversational awareness and (2) designing an interface to support this type of awareness. This chapter presents two innovative prototypes, namely Relaxed Instant Messenger (RIM) and Conversational Dock (ConDock). RIM integrates a sequential interface with an adaptive threaded interface to support awareness of turn-taking and conversational context. ConDock adopts a focus + context visualisation technique to support awareness of multiple conversations. The evaluations of the two prototypes show that they meet their design objectives and were found useful in enhancing group communication.

  13. Training Blind Children to Employ Appropriate Gaze Direction and Sitting Behavior during Conversation.

    ERIC Educational Resources Information Center

    Raver, Sharon A.

    1987-01-01

    Five congenitally blind children (ages 5-8) were trained to simultaneously employ appropriate gaze direction and sitting behavior while conversing with an adult. Training consisted of discussion, modeling, physical prompting, feedback, and positive reinforcement. All children reached criterion in 19 to 25 training sessions. (Author/DB)

  14. Direct Conversion of Chemically De-Ashed Coal in Fuel Cells (II)

    SciTech Connect

    Cooper, J F

    2005-07-25

    We review the technical challenges associated with the production and use of various coal chars in a direct carbon conversion fuel cell. Existing chemical and physical deashing processes remove material below levels impacting performance at minimal cost. At equilibrium, sulfur entrained is rejected from the melt as COS in the offgas.

  15. A Formalization of Floating Point Numeric Base Conversion

    DTIC Science & Technology

    The process of converting arbitrary real numbers into a floating point format is formalized as a mapping of the reals into a specified subset of real...numbers. The structure of this subset, the set of a significant digit base beta floating point numbers, is analyzed and properties of conversion...implications of these results with regards to establishing goals and standards for floating point formats and conversion procedures are considered.

  16. Conversion of Oxyfluoride Based Coated Conductors

    SciTech Connect

    Dan Wesolowski

    2006-11-01

    Direct measurements of HF pressure in equilibrium with the film during the BaF2 process are sorely needed. It is the HF partial pressure that governs the rate at which the film composition is changing and is, therefore, an important factor in controlling the composition/time trajectory of the film. Establishing the composition/time trajectory of both MOD-derived and e-beam derived films for a given set of conditions is another goal for the project. These studies will provide a fundamental understanding of the ex situ process for producing coated conductors.

  17. CSUMB: Military base conversion as an opportunity for sustainable design

    SciTech Connect

    McDonald, M.; Cooper, P.; Haggard, K.

    1995-11-01

    The conversion of military bases around the country creates an imperative to infuse social, economic, and environmental vitality back into the affected region. Fort Ord in Monterey County, a recent casualty of base closures, is being turned into an opportunity for adaptive reuse as it undergoes the transformation from an army base to a magnet campus of the California State University (CSU) system. The CSU Monterey Bay (CSUMB) campus visionaries included sustainability as a priority in the base conversion. To achieve this goal, the university hired a team of sustainable design consultants. This paper reports on the outcomes of the preliminary design and planning phases.

  18. An Acid-Base Chemistry Example: Conversion of Nicotine

    NASA Astrophysics Data System (ADS)

    Summerfield, John H.

    1999-10-01

    The current government interest in nicotine conversion by cigarette companies provides an example of acid-base chemistry that can be explained to students in the second semester of general chemistry. In particular, the conversion by ammonia of the +1 form of nicotine to the easier-to-assimilate free-base form illustrates the effect of pH on acid-base equilibrium. The part played by ammonia in tobacco smoke is analogous to what takes place when cocaine is "free-based".

  19. Dissection of Regulatory Elements During Direct Conversion of Somatic Cells into Neurons.

    PubMed

    Soleimani, Tahereh; Falsafi, Nafiseh; Fallahi, Hossein

    2017-02-23

    A revolutionary approach that involves direct conversion of somatic cells into almost any other types of cells showed promising results for regenerative medicine. Currently, producing valuable cell types including neurons, cardiomyocytes and hepatocytes through direct conversion of somatic cells appear to be a feasible option for regenerative medicine. The process involves inducing the cells by chemical cocktails or by expression of different types of transcription factors. In this concept, in vitro neurogenesis considered to be able to produce neuron cells to replace damaged neurons especially in Alzheimer and Parkinson disease. However, early successful experiments followed by major drawbacks such as low differentiation efficiency in producing neurons and detection of various undesirable types of cells in the culture. Therefore, there is not a single optimized common protocol for producing high quality neurons in vitro so far. This is partly due to the lack of our understanding about the precise cellular, genetic, and molecular mechanisms underlying neurogenesis via direct conversion. In the current work, we have employed meta-analysis tools and extensive gene regulatory network analysis on the high through put gene expression data obtained from previous reprogramming protocols to identify central gene regulatory components involved in direct conversion of fibroblasts into neurons. Our results identified miR-9, miR-30 as the most important miRNA and TP53, MYC, JUN, SP1 and SMAD2 considered to be the most important transcription factors. These findings would be useful for direct targeting these hub regulatory elements in order to increase the efficacy and specificity of the conversion protocols. This article is protected by copyright. All rights reserved.

  20. An introduction to thermodynamics of renewable cycles for direct solar energy conversion

    SciTech Connect

    Sukhodolsky, A.T.

    1998-07-01

    Mechanical energy is known to be converted into thermal form (heat) without any restriction. Any opposite conversion of heat into mechanical energy owing to work produced in the heat engines has been restricted by principle of Carnot. This communication is to introduce into the elements of thermodynamics for direct energy conversion of light into mechanical energy. The aim is to explain: why without any machines, the efficiency of conversion is able to be by many orders of magnitude greater than the efficiency of direct mechanical action of light given in framework of equilibrium radiation thermodynamics. The development of such a concept is to find out an actual fundamental restriction for the maximum conversion available in several new solar renewable technologies for both direct generation of mechanical vibrations and for extraction of pure water from mixtures owing to self-organization of heat cycles. In order to involve solar light under non-equilibrium with respect to matter as a motive power within thermodynamics, the principle of Carnot for heat engines is assumed to be also valid for renewable processes (cycles). The absorbing part of condensed matter by optical pumping is considered as a heat source for production of entropy by heat-transfer into dark surrounding that plays role of heat sink. Principle of Carnot is used together with common accepted definition of non-equilibrium entropy in order to describe the excitement of heat source and its next relaxation. The new formulation of Carnot theorem and fundamental maximum of renewable conversion is derived. The simplest system of two equal bodies with difference temperatures is considered to show how to find the maximum energy available for renewable conversion. The major difference between equilibrium (reversible) thermodynamics and proposed renewable (non-equilibrium) approach is discussed on this example together with a typical mathematical paradox.

  1. Feasibility study of direct-conversion x-ray detection using cadmium zinc telluride films

    NASA Astrophysics Data System (ADS)

    Kang, S.; Jung, B.; Noh, S.; Cho, C.; Yoon, I.; Park, J.

    2012-01-01

    Polycrystalline Cd(Zn)Te films deposited by vacuum thermal evaporation are investigated as a direct-conversion medium for x-ray detection. The use of evaporation techniques allows for the preparation of large-area films with the potential for large-area x-ray imaging with high spatial resolution. Films with compositions of Cd1-xZnxTe (x = 0.15,0.25,0.3) were prepared to a thickness of 20 μm on slide glass substrates with an aluminum or indium tin oxide (ITO) bottom electrode and a silver top electrode, with and without additional charge-blocking layers (CeO2 and parylene dielectric) between the electrode and CdZnTe film to reduce leakage current. Composition and structural analyses of the as-deposited films confirm the development of polycrystalline CdZnTe. Leakage current in the CdZnTe film is approximately ten times lower than for a comparable CdTe film, and the lowest leakage is obtained for a film with composition of Cd0.7Zn0.3Te The use of ITO rather than aluminum as the bottom electrode provides a further improvement in leakage current and improved stability. The Cd0.7Zn0.3Te-based device with ITO electrode and charge-blocking layers achieves the highest total output charge (180.44 pC/cm2 or 1.1 × 109 e-/cm2) and signal-to-noise ratio (6.19 at applied bias of 30 V). The present experiments show that Cd1-xZnxTe in a multilayer structure with charge-blocking layers is feasible as a good radiation conversion layer for flatpanel radiation imaging systems.

  2. A review of induced pluripotent stem cell, direct conversion by trans-differentiation, direct reprogramming and oligodendrocyte differentiation.

    PubMed

    Prasad, Ankshita; Manivannan, Janani; Loong, Daniel T B; Chua, Soo M; Gharibani, Payam M; All, Angelo H

    2016-03-01

    Rapid progress in the field of stem cell therapy and cellular reprogramming provides convincing evidence of its feasibility in treating a wide range of pathologies through autologous cell replacement therapy. This review article describes in detail on three widely used approaches of somatic cell reprogramming: induced pluripotent stem cells, direct conversion and direct reprogramming, in the context of demyelination in the CNS. The potential limitations of each reprogramming technique are reviewed along with their distinct molecular approach to reprogramming. This is followed by an analysis on the scopes and challenges of its translational applications in deriving oligodendrocyte progenitor cells and oligodendrocytes for cell replacement treatment of demyelinating conditions in the CNS.

  3. Direct Conversion of Free Space Millimeter Waves to Optical Domain by Plasmonic Modulator Antenna.

    PubMed

    Salamin, Yannick; Heni, Wolfgang; Haffner, Christian; Fedoryshyn, Yuriy; Hoessbacher, Claudia; Bonjour, Romain; Zahner, Marco; Hillerkuss, David; Leuchtmann, Pascal; Elder, Delwin L; Dalton, Larry R; Hafner, Christian; Leuthold, Juerg

    2015-12-09

    A scheme for the direct conversion of millimeter and THz waves to optical signals is introduced. The compact device consists of a plasmonic phase modulator that is seamlessly cointegrated with an antenna. Neither high-speed electronics nor electronic amplification is required to drive the modulator. A built-in enhancement of the electric field by a factor of 35,000 enables the direct conversion of millimeter-wave signals to the optical domain. This high enhancement is obtained via a resonant antenna that is directly coupled to an optical field by means of a plasmonic modulator. The suggested concept provides a simple and cost-efficient alternative solution to conventional schemes where millimeter-wave signals are first converted to the electrical domain before being up-converted to the optical domain.

  4. Direct Conversion of Free Space Millimeter Waves to Optical Domain by Plasmonic Modulator Antenna

    PubMed Central

    2015-01-01

    A scheme for the direct conversion of millimeter and THz waves to optical signals is introduced. The compact device consists of a plasmonic phase modulator that is seamlessly cointegrated with an antenna. Neither high-speed electronics nor electronic amplification is required to drive the modulator. A built-in enhancement of the electric field by a factor of 35 000 enables the direct conversion of millimeter-wave signals to the optical domain. This high enhancement is obtained via a resonant antenna that is directly coupled to an optical field by means of a plasmonic modulator. The suggested concept provides a simple and cost-efficient alternative solution to conventional schemes where millimeter-wave signals are first converted to the electrical domain before being up-converted to the optical domain. PMID:26570995

  5. CMOS linear-in-dB VGA with DC offset cancellation for direct-conversion receivers

    NASA Astrophysics Data System (ADS)

    Qianqian, Lei; Zhiming, Chen; Yin, Shi; Xiaojie, Chu; Zheng, Gong

    2011-10-01

    A low-power high-linearity linear-in-dB variable gain amplifier (VGA) with novel DC offset calibration loop for direct-conversion receiver (DCR) is proposed. The proposed VGA uses the differential-ramp based technique, a digitally programmable gain amplifier (PGA) can be converted to an analog controlled dB-linear VGA. An operational amplifier (OPAMP) utilizing an improved Miller compensation approach is adopted in this VGA design. The proposed VGA shows a 57 dB linear range. The DC offset cancellation (DCOC) loop is based on a continuous-time feedback that includes the Miller effect and a linear range operation MOS transistor to realize high-value capacitors and resistors to solve the DC offset problem, respectively. The proposed approach requires no external components and demonstrates excellent DCOC capability in measurement. Fabricated using SMIC 0.13 μm CMOS technology, this VGA dissipates 4.5 mW from a 1.2 V supply voltage while occupying 0.58 mm2 of chip area including bondpads. In addition, the DCOC circuit shows 500 Hz high pass cutoff frequency (HPCF) and the measured residual DC offset at the output of VGA is less than 2 mV.

  6. Solution-Processed Two-Dimensional Metal Dichalcogenide-Based Nanomaterials for Energy Storage and Conversion.

    PubMed

    Cao, Xiehong; Tan, Chaoliang; Zhang, Xiao; Zhao, Wei; Zhang, Hua

    2016-08-01

    The development of renewable energy storage and conversion devices is one of the most promising ways to address the current energy crisis, along with the global environmental concern. The exploration of suitable active materials is the key factor for the construction of highly efficient, highly stable, low-cost and environmentally friendly energy storage and conversion devices. The ability to prepare two-dimensional (2D) metal dichalcogenide (MDC) nanosheets and their functional composites in high yield and large scale via various solution-based methods in recent years has inspired great research interests in their utilization for renewable energy storage and conversion applications. Here, we will summarize the recent advances of solution-processed 2D MDCs and their hybrid nanomaterials for energy storage and conversion applications, including rechargeable batteries, supercapacitors, electrocatalytic hydrogen generation and solar cells. Moreover, based on the current progress, we will also give some personal insights on the existing challenges and future research directions in this promising field.

  7. Apparatus and methods for direct conversion of gaseous hydrocarbons to liquids

    DOEpatents

    Kong, Peter C.; Lessing, Paul A.

    2006-04-25

    A chemical reactor for direct conversion of hydrocarbons includes a dielectric barrier discharge plasma cell and a solid oxide electrochemical cell in fluid communication therewith. The discharge plasma cell comprises a pair of electrodes separated by a dielectric material and passageway therebetween. The electrochemical cell comprises a mixed-conducting solid oxide electrolyte membrane tube positioned between a porous cathode and a porous anode, and a gas inlet tube for feeding oxygen containing gas to the porous cathode. An inlet is provided for feeding hydrocarbons to the passageway of the discharge plasma cell, and an outlet is provided for discharging reaction products from the reactor. A packed bed catalyst may optionally be used in the reactor to increase efficiency of conversion. The reactor can be modified to allow use of a light source for directing ultraviolet light into the discharge plasma cell and the electrochemical cell.

  8. Thermionic Energy Conversion Based on Graphene van der Waals Heterostructures

    PubMed Central

    Liang, Shi-Jun; Liu, Bo; Hu, Wei; Zhou, Kun; Ang, L. K.

    2017-01-01

    Seeking for thermoelectric (TE) materials with high figure of merit (or ZT), which can directly converts low-grade wasted heat (400 to 500 K) into electricity, has been a big challenge. Inspired by the concept of multilayer thermionic devices, we propose and design a solid-state thermionic devices (as a power generator or a refrigerator) in using van der Waals (vdW) heterostructure sandwiched between two graphene electrodes, to achieve high energy conversion efficiency in the temperature range of 400 to 500 K. The vdW heterostructure is composed of suitable multiple layers of transition metal dichalcogenides (TMDs), such as MoS2, MoSe2, WS2 and WSe2. From our calculations, WSe2 and MoSe2 are identified as two ideal TMDs (using the reported experimental material’s properties), which can harvest waste heat at 400 K with efficiencies about 7% to 8%. To our best knowledge, this design is the first in combining the advantages of graphene electrodes and TMDs to function as a thermionic-based device. PMID:28387363

  9. Thermionic Energy Conversion Based on Graphene van der Waals Heterostructures

    NASA Astrophysics Data System (ADS)

    Liang, Shi-Jun; Liu, Bo; Hu, Wei; Zhou, Kun; Ang, L. K.

    2017-04-01

    Seeking for thermoelectric (TE) materials with high figure of merit (or ZT), which can directly converts low-grade wasted heat (400 to 500 K) into electricity, has been a big challenge. Inspired by the concept of multilayer thermionic devices, we propose and design a solid-state thermionic devices (as a power generator or a refrigerator) in using van der Waals (vdW) heterostructure sandwiched between two graphene electrodes, to achieve high energy conversion efficiency in the temperature range of 400 to 500 K. The vdW heterostructure is composed of suitable multiple layers of transition metal dichalcogenides (TMDs), such as MoS2, MoSe2, WS2 and WSe2. From our calculations, WSe2 and MoSe2 are identified as two ideal TMDs (using the reported experimental material’s properties), which can harvest waste heat at 400 K with efficiencies about 7% to 8%. To our best knowledge, this design is the first in combining the advantages of graphene electrodes and TMDs to function as a thermionic-based device.

  10. Direct conversion of alcohols to α-chloro aldehydes and α-chloro ketones.

    PubMed

    Jing, Yuanyuan; Daniliuc, Constantin G; Studer, Armido

    2014-09-19

    Direct conversion of primary and secondary alcohols into the corresponding α-chloro aldehydes and α-chloro ketones using trichloroisocyanuric acid, serving both as stoichiometric oxidant and α-halogenating reagent, is reported. For primary alcohols, TEMPO has to be added as an oxidation catalyst, and for the transformation of secondary alcohols (TEMPO-free protocol), MeOH as an additive is essential to promote chlorination of the intermediary ketones.

  11. Alternating Current-to-Direct Current Power Conversion by Single-Wall Carbon Nanotube Diodes

    DTIC Science & Technology

    2010-01-01

    Alternating current-to-direct current power conversion by single-wall carbon nanotube diodes Govind Mallick,1 Mark H. Griep,1 Pulickel M. Ajayan,2...Thio, Nature London 382, 54 1996. 6P. Collins, A. Zettl, H. Bando, A. Thess, and R . Smalley, Science 278, 100 1997. 7S. J. Tans, A. R . M...289, 94 2000. 11B. Satishkumar, P. John Thomas, A. Govindraj, and C. Rao, Appl. Phys. Lett. 77, 2530 2000. 12S. Heinze, J. Tersoff, R . Martel, V

  12. Direct conversion of methane to higher hydrocarbons using AlBr3-HBr superacid catalyst.

    PubMed

    Vasireddy, Sivakumar; Ganguly, Sreemoyee; Sauer, Joe; Cook, Wyndham; Spivey, James J

    2011-01-14

    The direct gas phase catalytic oligomerization of methane at temperatures ≤673 K has been demonstrated using AlBr(3)-HBr superacid. The reaction produces C(2)+ hydrocarbons and hydrogen in a single step at 1 atm in a continuous flow reactor at a nominal residence time of 60 s. The essentially complete conversion of methane appears to be due to protolytic activation of methane in the presence of H(+)AlBr(4)(-).

  13. Correction of Frequency-Dependent Nonlinear Errors in Direct-Conversion Transceivers

    DTIC Science & Technology

    2016-03-31

    Correction of Frequency-Dependent Nonlinear Errors in Direct-Conversion Transceivers Blake James & Caleb Fulton Advanced Radar Research Center...University of Oklahoma Norman, Oklahoma, USA, 73019 pyraminxrox@ou.edu, fulton@ou.edu Abstract: Correction of nonlinear and frequency dependent...frequency-dependent nonlinear distortion in modern highly digital phased arrays. The work presented here is done in the context of calibrating the

  14. 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.

  15. Ionic Liquid Based Conversion of Biomass to Hydrocarbon Fuels

    DTIC Science & Technology

    2008-08-01

    out at 90 °C Task 2 - Investigation of the catalytic hydrolysis /depolymerization of cellulose in ionic liquid solvents. Ionic liquids possess...Office Cellulose is the most abundant form of living biomass on earth. It has been estimated that the annual photosynthetic production of cellulose is...stored energy (solid cellulose ) is not directly accessible to modern military systems. To utilize this energy requires the conversion of solid

  16. Image quality of a prototype direct conversion detector for digital mammography

    NASA Astrophysics Data System (ADS)

    Mainprize, James G.; Ford, Nancy L.; Yin, Shi; Tumer, Tumay O.; Yaffe, Martin J.

    1999-05-01

    A digital mammography system in which the x-ray sensitive device is a solid-state direct conversion detector is under development. This detector is a 1 mm thick silicon photodiode array hybridized to a CCD read-out, with a 50 micrometer pixel pitch. The detector is designed to be used in a slot-scanned system using time-delay integration (TDI) for signal acquisition. To handle the large signal generated in the photodiode, a novel read-out technique was used, in which charge was integrated 'on-chip' over a small number of rows, and the output of each of these sections was digitally summed 'off-chip' to produce the total integrated signal for each pixel in the image. This two-stage integration process not only allows easy acquisition of large signals, it effectively increases bit depth from 12 bits (for a single section) to approximately 16 (for the total integrated signal). The image quality of the device has been measured and compared to predictions based on cascaded linear systems theory. The resolution of the new detector was determined from the modulation transfer function (MTF) which was obtained from over-sampled edge spread functions (ESF). The ESF was measured in both the scan and slot directions from four repeated images of a tantalum edge. Noise power spectra (NPS) were determined from 40 repeated flat-field images at each of several x-ray exposures. By combining the MTF and NPS measurements, the detective quantum efficiency (DQE) was also determined. The MTF in the non-scanned direction was found to greater than 20% at 10 mm-1 and slightly lower in the scanned direction (approximately equals 10% at 10 mm-1). In all cases, the DQE was at least comparable to film-screen mammography receptors. The DQE at 120 mR detector exposure at zero spatial frequency ranged from 0.4 to 0.6 depending on the sample tested. Electronic noise was fairly low, contributing to less than plus or minus 7 ADU (out of a possible 98304 ADU). Future work will involve re-designing the

  17. Synthesis gas production through biomass direct chemical looping conversion with natural hematite as an oxygen carrier.

    PubMed

    Huang, Zhen; He, Fang; Feng, Yipeng; Zhao, Kun; Zheng, Anqing; Chang, Sheng; Li, Haibin

    2013-07-01

    Biomass direct chemical looping (BDCL) conversion with natural hematite as an oxygen carrier was conducted in a fluidized bed reactor under argon atmosphere focusing on investigation the cyclic performance of oxygen carrier. The presence of oxygen carrier can evidently promote the biomass conversion. The gas yield and carbon conversion increased from 0.75 Nm(3)/kg and 62.23% of biomass pyrolysis to 1.06 Nm(3)/kg and 87.63% of BDCL, respectively. The components of the gas product in BDCL were close to those in biomass pyrolysis as the cyclic number increased. The gas yield and carbon conversion decreased from 1.06 Nm(3)/kg and 87.63% at 1st cycle to 0.93 Nm(3)/kg and 77.18% at 20th cycle, respectively, due to the attrition and structural changes of oxygen carrier. X-ray diffraction (XRD) analysis showed that the reduction extent of oxygen carrier increased with the cycles. Scanning electron microscope (SEM) and pore structural analysis displayed that agglomeration was observed with the cycles.

  18. Thermoelectric Oxide Modules (TOMs) for the Direct Conversion of Simulated Solar Radiation into Electrical Energy

    PubMed Central

    Tomeš, Petr; Trottmann, Matthias; Suter, Clemens; Aguirre, Myriam Heidi; Steinfeld, Aldo; Haueter, Philipp; Weidenkaff, Anke

    2010-01-01

    The direct conversion of concentrated high temperature solar heat into electrical energy was demonstrated with a series of four–leg thermoelectric oxide modules (TOM). These temperature stable modules were not yet optimized for high efficiency conversion, but served as proof-of-principle for high temperature conversion. They were constructed by connecting two p- (La1.98Sr0.02CuO4) and two n-type (CaMn0.98Nb0.02O3) thermoelements electrically in series and thermally in parallel. The temperature gradient ΔT was applied by a High–Flux Solar Simulator source (HFSS) which generates a spectrum similar to solar radiation. The influence of the graphite layer coated on the hot side of the Al2O3 substrate compared to the uncoated surface on ΔT, Pmax and η was studied in detail. The measurements show an almost linear temperature profile along the thermoelectric legs. The maximum output power of 88.8 mW was reached for a TOM with leg length of 5 mm at ΔT = 622 K. The highest conversion efficiency η was found for a heat flux of 4–8 W cm-2 and the dependence of η on the leg length was investigated.

  19. Conversion between geotropic and apogeotropic persistent direction-changing positional nystagmus.

    PubMed

    Shin, Jung Eun; Jeong, Kyung-Hwa; Ahn, Sung Hwan; Kim, Chang-Hee

    2015-01-01

    Clinical features in the course of conversion differed between patients with SSNHL and cupulopathy, which indicates that the pathophysiology of persistent geotropic or apogeotropic DCPN and the mechanism of the change in nystagmus direction may differ between the two groups. The aim of this study is to investigate clinical characteristics of 10 patients with persistent DCPN who exhibited a conversion of nystagmus direction between geotropic and apogeotropic, and discuss possible mechanisms. Using video-oculography, serial examinations of nystagmus in a head-roll test were performed. Of these 10 patients, five had sudden sensorineural hearing loss (SSNHL) and the remaining five had cupulopathy. In SSNHL, direction of nystagmus changed from geotropic to apogeotropic in three patients and from apogeotropic to geotropic in two patients. In cupulopathy, persistent apogeotropic DCPN always preceded persistent geotropic DCPN. The change in nystagmus direction occurred earlier in patients with cupulopathy (1 or 2 days after vertigo onset) than in patients with SSNHL (4-23 days after vertigo onset). While the null plane was consistently identified on one side, regardless of the nystagmus direction in cupulopathy, it was not always identified on the side of hearing loss in SSNHL.

  20. Photonic digital-to-analog conversion based on wavelength multiplexing

    NASA Astrophysics Data System (ADS)

    Yang, Shuna; Hu, Miao; Chi, Hao; Li, Qiliang

    2017-10-01

    A novel photonic digital-to-analog conversion (PDAC) scheme, which is based on optical intensity weighting and multiplexing/summing of different wavelengths, is proposed. The employment of wavelength multiplexing in the system, which conducts the function of modulated light intensity summation, greatly simplifies the system complexity and improves the conversion speed/accuracy limited by large-area photo-detectors and associated electronics. A 4-bit PDAC with a conversion speed of 10 GS/s demonstrates the feasibility of the proposed scheme. In addition, the performance degradation induced by the limited extinction ratios of the applied electro-optic modulators, the synchronization errors among different wavelength channels, and the bit resolutions of the built system is also discussed.

  1. Conversion of Low-Rank Wyoming Coals into Gasoline by Direct Liquefaction

    SciTech Connect

    Polyakov, Oleg

    2013-12-31

    Under the cooperative agreement program of DOE and funding from Wyoming State’s Clean Coal Task Force, Western Research Institute and Thermosolv LLC studied the direct conversion of Wyoming coals and coal-lignin mixed feeds into liquid fuels in conditions highly relevant to practice. During the Phase I, catalytic direct liquefaction of sub-bituminous Wyoming coals was investigated. The process conditions and catalysts were identified that lead to a significant increase of desirable oil fraction in the products. The Phase II work focused on systematic study of solvothermal depolymerization (STD) and direct liquefaction (DCL) of carbonaceous feedstocks. The effect of the reaction conditions (the nature of solvent, solvent/lignin ratio, temperature, pressure, heating rate, and residence time) on STD was investigated. The effect of a number of various additives (including lignin, model lignin compounds, lignin-derivable chemicals, and inorganic radical initiators), solvents, and catalysts on DCL has been studied. Although a significant progress has been achieved in developing solvothermal depolymerization, the side reactions – formation of considerable amounts of char and gaseous products – as well as other drawbacks do not render aqueous media as the most appropriate choice for commercial implementation of STD for processing coals and lignins. The trends and effects discovered in DCL point at the specific features of liquefaction mechanism that are currently underutilized yet could be exploited to intensify the process. A judicious choice of catalysts, solvents, and additives might enable practical and economically efficient direct conversion of Wyoming coals into liquid fuels.

  2. The alkali metal thermoelectric converter /AMTEC/ - A new direct energy conversion technology for aerospace power

    NASA Technical Reports Server (NTRS)

    Bankston, C. P.; Cole, T.; Jones, R.; Ewell, R.

    1982-01-01

    A thermally regenerative electrochemical device for the direct conversion of heat to electrical energy, the alkali metal thermoelectric converter (AMTEC), is characterized by potential efficiencies on the order of 15-40% and possesses no moving parts, making it a candidate for space power system applications. Device conversion efficiency is projected on the basis of experimental voltage vs current curves exhibiting power densities of 0.7 W/sq cm and measured electrode efficiencies of up to 40%. Preliminary radiative heat transfer measurements presented may be used in an investigation of methods for the reduction of AMTEC parasitic radiation losses. AMTEC assumes heat input and rejection temperatures of 900-1300 K and 400-800 K, respectively. The working fluid is liquid sodium, and the porous electrode employed is of molybdenum.

  3. A solar simulator-pumped gas laser for the direct conversion of solar energy

    NASA Technical Reports Server (NTRS)

    Weaver, W. R.; Lee, J. H.

    1981-01-01

    Most proposed space power systems are comprised of three general stages, including the collection of the solar radiation, the conversion to a useful form, and the transmission to a receiver. The solar-pumped laser, however, effectively eliminates the middle stage and offers direct photon-to-photon conversion. The laser is especially suited for space-to-space power transmission and communication because of minimal beam spread, low power loss over large distances, and extreme energy densities. A description is presented of the first gas laser pumped by a solar simulator that is scalable to high power levels. The lasant is an iodide C3F7I that as a laser-fusion driver has produced terawatt peak power levels.

  4. Test Results from a Direct Drive Gas Reactor Simulator Coupled to a Brayton Power Conversion Unit

    NASA Technical Reports Server (NTRS)

    Hervol, David S.; Briggs, Maxwell H.; Owen, Albert K.; Bragg-Sitton, Shannon M.; Godfroy, Thomas J.

    2010-01-01

    Component level testing of power conversion units proposed for use in fission surface power systems has typically been done using relatively simple electric heaters for thermal input. These heaters do not adequately represent the geometry or response of proposed reactors. As testing of fission surface power systems transitions from the component level to the system level it becomes necessary to more accurately replicate these reactors using reactor simulators. The Direct Drive Gas-Brayton Power Conversion Unit test activity at the NASA Glenn Research Center integrates a reactor simulator with an existing Brayton test rig. The response of the reactor simulator to a change in Brayton shaft speed is shown as well as the response of the Brayton to an insertion of reactivity, corresponding to a drum reconfiguration. The lessons learned from these tests can be used to improve the design of future reactor simulators which can be used in system level fission surface power tests.

  5. Bi-directional conversion between microwave and optical frequencies in a piezoelectric optomechanical device

    NASA Astrophysics Data System (ADS)

    Vainsencher, Amit; Satzinger, K. J.; Peairs, G. A.; Cleland, A. N.

    2016-07-01

    We describe the principles of design, fabrication, and operation of a piezoelectric optomechanical crystal with which we demonstrate bi-directional conversion of energy between microwave and optical frequencies. The optomechanical crystal has an optical mode at 1523 nm co-located with a mechanical breathing mode at 3.8 GHz, with a measured optomechanical coupling strength gom/2π of 115 kHz. The breathing mode is driven and detected by curved interdigitated transducers that couple to a Lamb mode in suspended membranes on either end of the optomechanical crystal, allowing the external piezoelectric modulation of the optical signal as well as the converse, the detection of microwave electrical signals generated by a modulated optical signal. We compare measurements to theory where appropriate.

  6. A solar simulator-pumped gas laser for the direct conversion of solar energy

    NASA Technical Reports Server (NTRS)

    Weaver, W. R.; Lee, J. H.

    1981-01-01

    Most proposed space power systems are comprised of three general stages, including the collection of the solar radiation, the conversion to a useful form, and the transmission to a receiver. The solar-pumped laser, however, effectively eliminates the middle stage and offers direct photon-to-photon conversion. The laser is especially suited for space-to-space power transmission and communication because of minimal beam spread, low power loss over large distances, and extreme energy densities. A description is presented of the first gas laser pumped by a solar simulator that is scalable to high power levels. The lasant is an iodide C3F7I that as a laser-fusion driver has produced terawatt peak power levels.

  7. Experimental Investigations of Direct and Converse Flexoelectric Effect in Bilayer Lipid Membranes.

    NASA Astrophysics Data System (ADS)

    Todorov, Angelio Todorov

    Flexoelectric coefficients (direct and converse), electric properties (capacitance and resistivity) and mechanical properties (thickness and elastic coefficients) have been determined for bilayer lipid membranes (BLMs) prepared from egg yolk lecithin (EYL), glycerol monoleate (GMO), phosphatidyl choline (PC) and phosphatidyl serine (PS) as a function of frequency, pH and surface charge modifiers. Direct flexoelectric effect manifested itself in the development of microvolt range a.c. potential (U_{f}) upon subjecting one side of a BLM to an oscillating hydrostatic pressure, in the 100-1000 Hz range. Operationally, the flexoelectric coefficient (f) is expressed by the ratio between U_{f} and the change of curvature (c) which accompanied the flexing of the membrane. Membrane curvature was determined by means of either the electric method (capacitance microphone effect) or by the newly developed method of stroboscopic interferometry. Real-time stroboscopic interferometry coupled with simultaneous electric measurements, provided a direct method for the determination of f. Two different frequency regimes of f were recognized. At low frequencies (<300 Hz), associated with free mobility of the surfactant, f-values of 24.1 times 10^{-19} and 0.87 times 10^ {-19} Coulombs were obtained for PC and GMO BLMs. At high frequencies (>300 Hz), associated with blocked mobility of the surfactant, f-values of 16.5 times 10^ {-19} and 0.30 times 10^{-19} Coulombs were obtained for PC and GMO BLMs. The theoretically calculated value for the GMO BLM oscillating at high frequency (0.12 times 10^{-19 } Coulombs) agreed well with that determined experimentally (0.3 times 10 ^{-19} Coulombs). For charged bovine brain PS BLM the observed flexocoefficient was f = 4.0 times 10^{ -18} Coulombs. Converse flexoelectric effect manifested itself in voltage-induced BLM curvature. Observations were carried out on uranyl acetate (UA) stabilized PS BLM under a.c. excitation. Frequency dependence of f

  8. Design of video interface conversion system based on FPGA

    NASA Astrophysics Data System (ADS)

    Zhao, Heng; Wang, Xiang-jun

    2014-11-01

    This paper presents a FPGA based video interface conversion system that enables the inter-conversion between digital and analog video. Cyclone IV series EP4CE22F17C chip from Altera Corporation is used as the main video processing chip, and single-chip is used as the information interaction control unit between FPGA and PC. The system is able to encode/decode messages from the PC. Technologies including video decoding/encoding circuits, bus communication protocol, data stream de-interleaving and de-interlacing, color space conversion and the Camera Link timing generator module of FPGA are introduced. The system converts Composite Video Broadcast Signal (CVBS) from the CCD camera into Low Voltage Differential Signaling (LVDS), which will be collected by the video processing unit with Camera Link interface. The processed video signals will then be inputted to system output board and displayed on the monitor.The current experiment shows that it can achieve high-quality video conversion with minimum board size.

  9. Direct conversion of plant biomass to ethanol by engineered Caldicellulosiruptor bescii.

    PubMed

    Chung, Daehwan; Cha, Minseok; Guss, Adam M; Westpheling, Janet

    2014-06-17

    Ethanol is the most widely used renewable transportation biofuel in the United States, with the production of 13.3 billion gallons in 2012 [John UM (2013) Contribution of the Ethanol Industry to the Economy of the United States]. Despite considerable effort to produce fuels from lignocellulosic biomass, chemical pretreatment and the addition of saccharolytic enzymes before microbial bioconversion remain economic barriers to industrial deployment [Lynd LR, et al. (2008) Nat Biotechnol 26(2):169-172]. We began with the thermophilic, anaerobic, cellulolytic bacterium Caldicellulosiruptor bescii, which efficiently uses unpretreated biomass, and engineered it to produce ethanol. Here we report the direct conversion of switchgrass, a nonfood, renewable feedstock, to ethanol without conventional pretreatment of the biomass. This process was accomplished by deletion of lactate dehydrogenase and heterologous expression of a Clostridium thermocellum bifunctional acetaldehyde/alcohol dehydrogenase. Whereas wild-type C. bescii lacks the ability to make ethanol, 70% of the fermentation products in the engineered strain were ethanol [12.8 mM ethanol directly from 2% (wt/vol) switchgrass, a real-world substrate] with decreased production of acetate by 38% compared with wild-type. Direct conversion of biomass to ethanol represents a new paradigm for consolidated bioprocessing, offering the potential for carbon neutral, cost-effective, sustainable fuel production.

  10. Direct Conversion of Plant Biomass to Ethanol by Engineered Caldicellulosiruptor bescii

    SciTech Connect

    Chung, Daehwan; Cha, Minseok; Guss, Adam M; Westpheling, Janet

    2014-01-01

    Ethanol is the most widely used renewable transportation biofuel in the United States, with the production of 13.3 billion gallons in 2012 [John UM (2013) Contribution of the Ethanol Industry to the Economy of the United States]. Despite considerable effort to produce fuels from lignocellulosic biomass, chemical pretreatment and the addition of saccharolytic enzymes before microbial bioconversion remain economic barriers to industrial deployment [Lynd LR, et al. (2008) Nat Biotechnol 26(2):169-172]. We began with the thermophilic, anaerobic, cellulolytic bacterium Caldicellulosiruptor bescii, which efficiently uses unpretreated biomass, and engineered it to produce ethanol. Here we report the direct conversion of switchgrass, a nonfood, renewable feedstock, to ethanol without conventional pretreatment of the biomass. This process was accomplished by deletion of lactate dehydrogenase and heterologous expression of a Clostridium thermocellum bifunctional acetaldehyde/alcohol dehydrogenase. Whereas wild-type C. bescii lacks the ability to make ethanol, 70% of the fermentation products in the engineered strain were ethanol [12.8 mM ethanol directly from 2% (wt/vol) switchgrass, a real-world substrate] with decreased production of acetate by 38% compared with wild-type. Direct conversion of biomass to ethanol represents a new paradigm for consolidated bioprocessing, offering the potential for carbon neutral, cost-effective, sustainable fuel production.

  11. Direct conversion of plant biomass to ethanol by engineered Caldicellulosiruptor bescii

    PubMed Central

    Chung, Daehwan; Cha, Minseok; Guss, Adam M.; Westpheling, Janet

    2014-01-01

    Ethanol is the most widely used renewable transportation biofuel in the United States, with the production of 13.3 billion gallons in 2012 [John UM (2013) Contribution of the Ethanol Industry to the Economy of the United States]. Despite considerable effort to produce fuels from lignocellulosic biomass, chemical pretreatment and the addition of saccharolytic enzymes before microbial bioconversion remain economic barriers to industrial deployment [Lynd LR, et al. (2008) Nat Biotechnol 26(2):169–172]. We began with the thermophilic, anaerobic, cellulolytic bacterium Caldicellulosiruptor bescii, which efficiently uses unpretreated biomass, and engineered it to produce ethanol. Here we report the direct conversion of switchgrass, a nonfood, renewable feedstock, to ethanol without conventional pretreatment of the biomass. This process was accomplished by deletion of lactate dehydrogenase and heterologous expression of a Clostridium thermocellum bifunctional acetaldehyde/alcohol dehydrogenase. Whereas wild-type C. bescii lacks the ability to make ethanol, 70% of the fermentation products in the engineered strain were ethanol [12.8 mM ethanol directly from 2% (wt/vol) switchgrass, a real-world substrate] with decreased production of acetate by 38% compared with wild-type. Direct conversion of biomass to ethanol represents a new paradigm for consolidated bioprocessing, offering the potential for carbon neutral, cost-effective, sustainable fuel production. PMID:24889625

  12. Multimode waveguide based directional coupler

    NASA Astrophysics Data System (ADS)

    Ahmed, Rajib; Rifat, Ahmmed A.; Sabouri, Aydin; Al-Qattan, Bader; Essa, Khamis; Butt, Haider

    2016-07-01

    The Silicon-on-Insulator (SOI) based platform overcomes limitations of the previous copper and fiber based technologies. Due to its high index difference, SOI waveguide (WG) and directional couplers (DC) are widely used for high speed optical networks and hybrid Electro-Optical inter-connections; TE00-TE01, TE00-TE00 and TM00-TM00 SOI direction couplers are designed with symmetrical and asymmetrical configurations to couple with TE00, TE01 and TM00 in a multi-mode semi-triangular ring-resonator configuration which will be applicable for multi-analyte sensing. Couplers are designed with effective index method and their structural parameters are optimized with consideration to coupler length, wavelength and polarization dependence. Lastly, performance of the couplers are analyzed in terms of cross-talk, mode overlap factor, coupling length and coupling efficiency.

  13. Uniformity of direct and converse magnetoelectric effects in magnetostrictive-piezoelectric composites

    NASA Astrophysics Data System (ADS)

    Liu, Guoxi; Dong, Shuxiang

    2014-09-01

    In this paper, we theoretically and experimentally confirmed the uniformity of magnetoelectric (ME) coupling coefficients for the direct and converse ME (DME and CME) effects in longitudinal-transverse (L-T) mode magnetostrictive-piezoelectric two-phase composites, both at low frequencies and in the electromechanical resonance region. We also discussed the flaws in previous measurements of the ME coupling coefficients, which led to misunderstandings in the uniformity between the DME and CME effects. Our current work provided a correct method to correctly understand ME coupling in magnetostrictive-piezoelectric two-phase composites.

  14. Developing Low-Intermediate Temperature Fuel Cells for Direct Conversion of Methane to Methanol Fuel

    SciTech Connect

    Torabi, A.; Barton, J.; Willman, C.; Ghezel-Ayagh, H.; Li, N.; Poozhikunnath, A.; Maric, R.; Marina, O. A.

    2016-04-26

    The objective of this project is development of a durable, low-cost, and high performance Low Temperature Solid Oxide Fuel Cell (LT-SOFC) for direct conversion of methane to methanol and other liquids, characterized by: a) operating temperature < 500oC, b) current density of > 100 mA/cm2 in liquid hydrocarbon production mode, c) continuous operation of > 100 h, d) cell area >100 cm2, e) cell cost per rate of product output < 100,000/bpd, f) process intensity of > 0.1 bpd/ft3, g) product yield and carbon efficiency > 50%, and h) volumetric output per cell > 30 L/day.

  15. Direct conversion of light hydrocarbon gases to liquid fuel. Final report No. 33

    SciTech Connect

    Kaplan, R.D.; Foral, M.J.

    1992-05-16

    Amoco oil Company, has investigated the direct, non-catalytic conversion of light hydrocarbon gases to liquid fuels (particularly methanol) via partial oxidation. The primary hydrocarbon feed used in these studies was natural gas. This report describes work completed in the course of our two-year project. In general we determined that the methanol yields delivered by this system were not high enough to make it economically attractive. Process variables studied included hydrocarbon feed composition, oxygen concentration, temperature and pressure effects, residence time, reactor design, and reactor recycle.

  16. Food waste-to-energy conversion technologies: current status and future directions.

    PubMed

    Pham, Thi Phuong Thuy; Kaushik, Rajni; Parshetti, Ganesh K; Mahmood, Russell; Balasubramanian, Rajasekhar

    2015-04-01

    Food waste represents a significantly fraction of municipal solid waste. Proper management and recycling of huge volumes of food waste are required to reduce its environmental burdens and to minimize risks to human health. Food waste is indeed an untapped resource with great potential for energy production. Utilization of food waste for energy conversion currently represents a challenge due to various reasons. These include its inherent heterogeneously variable compositions, high moisture contents and low calorific value, which constitute an impediment for the development of robust, large scale, and efficient industrial processes. Although a considerable amount of research has been carried out on the conversion of food waste to renewable energy, there is a lack of comprehensive and systematic reviews of the published literature. The present review synthesizes the current knowledge available in the use of technologies for food-waste-to-energy conversion involving biological (e.g. anaerobic digestion and fermentation), thermal and thermochemical technologies (e.g. incineration, pyrolysis, gasification and hydrothermal oxidation). The competitive advantages of these technologies as well as the challenges associated with them are discussed. In addition, the future directions for more effective utilization of food waste for renewable energy generation are suggested from an interdisciplinary perspective.

  17. Direct conversion of wet algae to crude biodiesel under supercritical ethanol conditions

    SciTech Connect

    Reddy, Harvind K.; Muppaneni, Tapaswy; Patil, Prafulla D.; Ponnusamy, Sundaravadivelnathan; Cooke, Peter; Schaub, Tanner; Deng, Shuguang

    2013-08-06

    This paper presents a single-step, environmentally friendly approach for the direct conversion of wet algae to crude biodiesel under supercritical ethanol conditions. Ethanol was used for the simultaneous extraction and transesterification of lipids in algae to produce fatty acid ethyl esters at supercritical conditions. In this work the effects of process parameters dry algae to ethanol (wt./vol.) ratio (1:6-1:15), reaction temperature (245-270 C), and reaction time (2-30 min.) on the yield of fatty acid ethyl esters (FAEE) were studied. 67% conversion was achieved at 265 C and 20 min of reaction time. The calorific value of a purified biodiesel sample produced at optimum conditions was measured to be 43 MJ/kg, which is higher than that of fatty acid methyl esters produced from the same biomass. The purified fatty acid ethyl esters were analyzed using GC-MS and FTIR. TGA analysis of algal biomass and purified FAEE was presented along with TEM images of the biomass captured before and after supercritical ethanol transesterification. This green conversion process has the potential to provide an energy-efficient and economical route for the production of renewable biodiesel production.

  18. 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.

  19. Phase matching considerations in second harmonic generation from tissues: Effects on emission directionality, conversion efficiency and observed morphology

    NASA Astrophysics Data System (ADS)

    LaComb, Ronald; Nadiarnykh, Oleg; Townsend, Sallie S.; Campagnola, Paul J.

    2008-04-01

    We present a heuristic treatment which relates SHG image intensities, signal directionality, and observed morphology to the physical structure of collagen and cellulose fibrillar tissues. The SHG creation model is based upon relaxed phase matching conditions which account for dispersion, randomness, and axial momentum contributions from the media, and includes a mathematical treatment which relates SHG conversion efficiency to fibril diameter and packing through the inclusion of potential intensity amplification resultant from quasi-phase matching (QPM). A direct consequence of this theory is that SHG in biological tissues is not strictly a coherent process, and that the forward directed SHG has a longer coherence length than the backward component, Through this treatment, we show that the emission directionality and also conversion efficiency do not arise solely from the fibril size but also depend on packing density and order of the inter-fibril structure. We demonstrate these principles in comparing the SHG response in normal and Osteogenesis Imperfecta (OI) skin. We show that the observed directionality and decreased relative intensity in the diseased state is consistent with phase matching conditions arising from the decreased fibril size and more random assembly. We further use this theory to explain the differences in morphology seen in forward and backward collected SHG in fibrillar tissues (e.g., collagenous and cellulosic). Specifically, we attribute segmented appearance to destructive interference between small fibrils separated by less than the coherence length. We suggest the approach based on relaxed phasematching conditions is general in predicting the SHG response in tissues and may be broadly applicable in interpreting the SHG contrast for diagnostic applications.

  20. Efficient pre-ionization by direct X-B mode conversion in VEST

    NASA Astrophysics Data System (ADS)

    Jo, JongGab; Lee, H. Y.; Kim, S. C.; Kim, S. H.; An, Y. H.; Hwang, Y. S.

    2017-01-01

    Pre-ionization experiments with pure toroidal field have been carried out in VEST (Versatile Experiment Spherical Torus) to investigate the feasibility of direct XB mode conversion from perpendicular LFS (Low Field Side) injection for efficient pre-ionization. Pre-ionization plasmas are studied by measuring the electron density and temperature profiles with respect to microwave power and toroidal field strength, and 2D full wave cold plasma simulation using the COMSOL Multiphysics is performed for the comparison. It is experimentally figured out that exceeding the threshold microwave power (>3 kW), the parametric decay and localized collisional heating is observed near the UHR (Upper Hybrid Resonance), and the efficient XB mode conversion can be achieved in both short density scale length (Ln) and magnetic scale length (LB) region positioned at outboard and inboard sides, respectively. From the 2D full wave simulations, the reflection and tunneling of X-wave near the R-cutoff layer according to the measured electron density profiles are analyzed with electric field polarization and power flow. Threshold electric field and wave power density for parametric decay are evaluated at least more than 4.8 × 104 V/m and 100 W/cm2, respectively. This study shows that efficient pre-ionization schemes using direct XB mode conversion can be realized by considering the key factors such as Ln, LB, and transmitted wave power at the UHR. Application to Ohmic start-up experiment is carried out to confirm the effect of the pre-ionization schemes on tokamak plasma start-up in VEST.

  1. A rapid method for direct detection of metabolic conversion and magnetization exchange with application to hyperpolarized substrates

    NASA Astrophysics Data System (ADS)

    Larson, Peder E. Z.; Kerr, Adam B.; Leon Swisher, Christine; Pauly, John M.; Vigneron, Daniel B.

    2012-12-01

    In this work, we present a new MR spectroscopy approach for directly observing nuclear spins that undergo exchange, metabolic conversion, or, generally, any frequency shift during a mixing time. Unlike conventional approaches to observe these processes, such as exchange spectroscopy (EXSY), this rapid approach requires only a single encoding step and thus is readily applicable to hyperpolarized MR in which the magnetization is not replenished after T1 decay and RF excitations. This method is based on stimulated-echoes and uses phase-sensitive detection in conjunction with precisely chosen echo times in order to separate spins generated during the mixing time from those present prior to mixing. We are calling the method Metabolic Activity Decomposition Stimulated-echo Acquisition Mode or MAD-STEAM. We have validated this approach as well as applied it in vivo to normal mice and a transgenic prostate cancer mouse model for observing pyruvate-lactate conversion, which has been shown to be elevated in numerous tumor types. In this application, it provides an improved measure of cellular metabolism by separating [1-13C]-lactate produced in tissue by metabolic conversion from [1-13C]-lactate that has flowed into the tissue or is in the blood. Generally, MAD-STEAM can be applied to any system in which spins undergo a frequency shift.

  2. A Rapid Method for Direct Detection of Metabolic Conversion and Magnetization Exchange with Application to Hyperpolarized Substrates

    PubMed Central

    Larson, Peder E. Z.; Kerr, Adam B.; Leon Swisher, Christine; Pauly, John M.; Vigneron, Daniel B.

    2012-01-01

    In this work, we present a new MR spectroscopy approach for directly observing nuclear spins that undergo exchange, metabolic conversion, or, generally, any frequency shift during a mixing time. Unlike conventional approaches to observe these processes, such as exchange spectroscopy (EXSY), this rapid approach requires only a single encoding step and thus is readily applicable to hyperpolarized MR in which the magnetization is not replenished after T1 decay and RF excitations. This method is based on stimulated-echoes and uses phase-sensitive detection in conjunction with precisely chosen echo times in order to separate spins generated during the mixing time from those present prior to mixing. We are calling the method Metabolic Activity Decomposition Stimulated-echo Acquisition Mode or MAD-STEAM. We have validated this approach as well as applied it in vivo to normal mice and a transgenic prostate cancer mouse model for observing pyruvate-lactate conversion, which has been shown to be elevated in numerous tumor types. In this application, it provides an improved measure of cellular metabolism by separating [1-13C]-lactate produced in tissue by metabolic conversion from [1-13C]-lactate that has flowed into the tissue or is in the blood. Generally, MAD-STEAM can be applied to any system in which spins undergo a frequency shift. PMID:23143011

  3. 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.

  4. Engineering of beam direct conversion for a 120-kV, 1-MW ion beam

    NASA Technical Reports Server (NTRS)

    Barr, W. L.; Doggett, J. N.; Hamilton, G. W.; Kinney, J. D.; Moir, R. W.

    1977-01-01

    Practical systems for beam direct conversion are required to recover the energy from ion beams at high efficiency and at very high beam power densities in the environment of a high-power neutral-injection system. Such an experiment is now in progress using a 120-kV beam with a maximum total current of 20 A. After neutralization, the H(+) component to be recovered will have a power of approximately 1 MW. A system testing these concepts has been designed and tested at 15 kV, 2 kW in preparation for the full-power tests. The engineering problems involved in the full-power tests affect electron suppression, gas pumping, voltage holding, diagnostics, and measurement conditions. Planning for future experiments at higher power includes the use of cryopumping and electron suppression by a magnetic field rather than by an electrostatic field. Beam direct conversion for large fusion experiments and reactors will save millions of dollars in the cost of power supplies and electricity and will dispose of the charged beam under conditions that may not be possible by other techniques.

  5. DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JANUARY 1, 2002 THROUGH MARCH 31, 2002

    SciTech Connect

    L.C. BROWN

    2002-03-31

    Direct energy conversion is the only potential means for producing electrical energy from a fission reactor without the Carnot efficiency limitations. This project was undertaken by Sandia National Laboratories, Los Alamos National Laboratories, The University of Florida, Texas A&M University and General Atomics to explore the possibilities of direct energy conversion. Other means of producing electrical energy from a fission reactor, without any moving parts, are also within the statement of proposed work. This report documents the efforts of General Atomics. Sandia National Laboratories, the lead laboratory, provides overall project reporting and documentation. The highlights of this reporting period are: (1) Cooling of the vapor core reactor and the MHD generator was incorporated into the Vapor Core Reactor model using standard heat transfer calculation methods. (2) Fission product removal, previously modeled as independent systems for each class of fission product, was incorporated into the overall fuel recycle loop of the Vapor Core Reactor. The model showed that the circulating activity levels are quite low. (3) Material distribution calculations were made for the ''pom-pom'' style cathode for the Fission Electric Cell. Use of a pom-pom cathode will eliminate the problem of hoop stress in the thin spherical cathode caused by the electric field.

  6. A field-shaping multi-well avalanche detector for direct conversion amorphous selenium

    SciTech Connect

    Goldan, A. H.; Zhao, W.

    2013-01-15

    Purpose: A practical detector structure is proposed to achieve stable avalanche multiplication gain in direct-conversion amorphous selenium radiation detectors. Methods: The detector structure is referred to as a field-shaping multi-well avalanche detector. Stable avalanche multiplication gain is achieved by eliminating field hot spots using high-density avalanche wells with insulated walls and field-shaping inside each well. Results: The authors demonstrate the impact of high-density insulated wells and field-shaping to eliminate the formation of both field hot spots in the avalanche region and high fields at the metal-semiconductor interface. Results show a semi-Gaussian field distribution inside each well using the field-shaping electrodes, and the electric field at the metal-semiconductor interface can be one order-of-magnitude lower than the peak value where avalanche occurs. Conclusions: This is the first attempt to design a practical direct-conversion amorphous selenium detector with avalanche gain.

  7. Effects of terminal nonhomology and homeology on double-strand-break-induced gene conversion tract directionality.

    PubMed Central

    Nelson, H H; Sweetser, D B; Nickoloff, J A

    1996-01-01

    Double-strand breaks (DSBs) greatly enhance gene conversion in the yeast Saccharomyces cerevisiae. In prior plasmid x chromosome crosses, conversion tracts were often short ( < 53 bp) and usually extended in only one direction from a DSB in an HO recognition sequence inserted into ura3. To allow fine-structure analysis of short and unidirectional tracts, phenotypically silent markers were introduced at 3- and 6-bp intervals flanking the HO site. These markers, which created a 70-bp homeologous region (71% homology), greatly increased the proportion of bidirectional tracts. Among products with short or unidirectional tracts, 85% were highly directional, converting markers on only one side (the nearest marker being 6 bp from the HO site). A DSB in an HO site insertion creates terminal nonhomologies. The high degree of directionality is a likely consequence of the precise cleavage at homology/nonhomology borders in hybrid DNA by Rad1/10 endonuclease. In contrast, terminal homeology alone yielded mostly unidirectional tracts. Thus, nonhomology flanked by homeology yields primarily bidirectional tracts, but terminal homeology or nonhomology alone yields primarily unidirectional tracts. These results are inconsistent with uni- and bidirectional tracts arising from one- and two-ended invasion mechanisms, respectively, as reduced homology would be expected to favor one-ended events. Tract spectra with terminal homeology alone with similar in RAD1 and rad1 cells, indicating that the high proportion of bidirectional tracts seen with homeology flanking nonhomology is not a consequence of Rad1/10 cleavage at homology/homeology boundaries. Instead, tract directionality appears to reflect the influence of the degree of broken-end homology on mismatch repair. PMID:8649406

  8. Direct Logistic Fuel JP-8 Conversion in a Liquid Tin Anode Solid Oxide Fuel Cell (LTA-SOFC)

    DTIC Science & Technology

    2008-04-09

    Oxide Fuel Cell (LTA- SOFC ) Prepared By CellTech Power , LLC, 131 Flanders Road, MA, 01581 April, 2008 Final Report Contract... REPORT Direct Logistic Fuel JP-8 Conversion in a Liquid Tin Anode Solid Oxide Fuel Cell (LTA- SOFC ) 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: This...logistic fuel only. The aim of this program was to advance LTA- SOFC technology with respect to direct conversion of JP-8. U 1. REPORT DATE (DD-MM-YYYY) 4

  9. Direct conversion of methane to C sub 2 's and liquid fuels

    SciTech Connect

    Warren, B.K.; Campbell, K.D.; Matherne, J.L.; Kinkade, N.E.

    1990-03-12

    The objectives of the project are to discover and evaluate novel catalytic systems for the conversion of methane or by-product light hydrocarbon gases either indirectly (through intermediate light gases rich in C{sub 2}'s) or directly to liquid hydrocarbon fuels, and to evaluate, from an engineering perspective, different conceptualized schemes. The approach is to carry out catalyst testing on several specific classes of potential catalysts for the conversion of methane selectively to C{sub 2} products. The behavior of alkaline earth/metal oxide/halide catalysts containing strontium was found to be different from the behavior of catalysts containing barium. Two approaches were pursued to avoid the heterogeneous/homogeneous mechanism in order to achieve higher C{sub 2} selectivity/methane conversion combinations. One approach was to eliminate or minimize the typical gas phase combustion chemistry and make more of the reaction occur on the surface of the catalyst by using silver. Another approach was to change the gas phase chemistry to depart from the typical combustion reaction network by using vapor-phase catalysts. The layered perovskite K{sub 2}La{sub 2}Ti{sub 3}O{sub 10} was further studied. Modifications of process and catalyst variables for LaCaMnCoO{sub 6} catalysts resulted in catalysts with superior performance. Results obtained with a literature catalyst Na{sub 2}CO{sub 3}/Pr{sub 6}O{sub 11} were better than those obtained with NaCO{sub 3}/Pr-Ce oxide or Na{sub 2}CO{sub 3}/Ag-Pr-Ce oxide. 52 refs., 15 figs., 9 tabs.

  10. Direct-conversion flat-panel imager with avalanche gain: Feasibility investigation for HARP-AMFPI

    PubMed Central

    Wronski, M. M.; Rowlands, J. A.

    2008-01-01

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10−7–10−2 R∕frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct

  11. Direct-conversion flat-panel imager with avalanche gain: feasibility investigation for HARP-AMFPI.

    PubMed

    Wronski, M M; Rowlands, J A

    2008-12-01

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10(-7)-10(-2) R/frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct interaction

  12. Direct-conversion flat-panel imager with avalanche gain: Feasibility investigation for HARP-AMFPI

    SciTech Connect

    Wronski, M. M.; Rowlands, J. A.

    2008-12-15

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10{sup -7}-10{sup -2} R/frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct

  13. Genome and Transcriptome of Clostridium phytofermentans, Catalyst for the Direct Conversion of Plant Feedstocks to Fuels

    DOE PAGES

    Petit, Elsa; Coppi, Maddalena V.; Hayes, James C.; ...

    2015-06-02

    Clostridium phytofermentans was isolated from forest soil and is distinguished by its capacity to directly ferment plant cell wall polysaccharides into ethanol as the primary product, suggesting that it possesses unusual catabolic pathways. The objective of our present study was to understand the molecular mechanisms of biomass conversion to ethanol in a single organism, Clostridium phytofermentans, by analyzing its complete genome and transcriptome during growth on plant carbohydrates. The saccharolytic versatility of C. phytofermentans is reflected in a diversity of genes encoding ATP-binding cassette sugar transporters and glycoside hydrolases, many of which may have been acquired through horizontal gene transfer.more » These genes are frequently organized as operons that may be controlled individually by the many transcriptional regulators identified in the genome. Preferential ethanol production may be due to high levels of expression of multiple ethanol dehydrogenases and additional pathways maximizing ethanol yield. The genome also encodes three different proteinaceous bacterial microcompartments with the capacity to compartmentalize pathways that divert fermentation intermediates to various products. Lastly, these characteristics make C. phytofermentans an attractive resource for improving the efficiency and speed of biomass conversion to biofuels.« less

  14. Direct solar-to-hydrogen conversion via inverted metamorphic multi-junction semiconductor architectures

    DOE PAGES

    Young, James L.; Steiner, Myles A.; Döscher, Henning; ...

    2017-03-13

    Solar water splitting via multi-junction semiconductor photoelectrochemical cells provides direct conversion of solar energy to stored chemical energy as hydrogen bonds. Economical hydrogen production demands high conversion efficiency to reduce balance-of-systems costs. For sufficient photovoltage, water-splitting efficiency is proportional to the device photocurrent, which can be tuned by judicious selection and integration of optimal semiconductor bandgaps. Here, we demonstrate highly efficient, immersed water-splitting electrodes enabled by inverted metamorphic epitaxy and a transparent graded buffer that allows the bandgap of each junction to be independently varied. Voltage losses at the electrolyte interface are reduced by 0.55 V over traditional, uniformly p-dopedmore » photocathodes by using a buried p-n junction. Lastly, advanced on-sun benchmarking, spectrally corrected and validated with incident photon-to-current efficiency, yields over 16% solar-to-hydrogen efficiency with GaInP/GaInAs tandem absorbers, representing a 60% improvement over the classical, high-efficiency tandem III-V device.« less

  15. Genome and Transcriptome of Clostridium phytofermentans, Catalyst for the Direct Conversion of Plant Feedstocks to Fuels

    PubMed Central

    Petit, Elsa; Coppi, Maddalena V.; Hayes, James C.; Tolonen, Andrew C.; Warnick, Thomas; Latouf, William G.; Amisano, Danielle; Biddle, Amy; Mukherjee, Supratim; Ivanova, Natalia; Lykidis, Athanassios; Land, Miriam; Hauser, Loren; Kyrpides, Nikos; Henrissat, Bernard; Lau, Joanne; Schnell, Danny J.; Church, George M.; Leschine, Susan B.; Blanchard, Jeffrey L.

    2015-01-01

    Clostridium phytofermentans was isolated from forest soil and is distinguished by its capacity to directly ferment plant cell wall polysaccharides into ethanol as the primary product, suggesting that it possesses unusual catabolic pathways. The objective of the present study was to understand the molecular mechanisms of biomass conversion to ethanol in a single organism, Clostridium phytofermentans, by analyzing its complete genome and transcriptome during growth on plant carbohydrates. The saccharolytic versatility of C. phytofermentans is reflected in a diversity of genes encoding ATP-binding cassette sugar transporters and glycoside hydrolases, many of which may have been acquired through horizontal gene transfer. These genes are frequently organized as operons that may be controlled individually by the many transcriptional regulators identified in the genome. Preferential ethanol production may be due to high levels of expression of multiple ethanol dehydrogenases and additional pathways maximizing ethanol yield. The genome also encodes three different proteinaceous bacterial microcompartments with the capacity to compartmentalize pathways that divert fermentation intermediates to various products. These characteristics make C. phytofermentans an attractive resource for improving the efficiency and speed of biomass conversion to biofuels. PMID:26035711

  16. Genome and Transcriptome of Clostridium phytofermentans, Catalyst for the Direct Conversion of Plant Feedstocks to Fuels.

    PubMed

    Petit, Elsa; Coppi, Maddalena V; Hayes, James C; Tolonen, Andrew C; Warnick, Thomas; Latouf, William G; Amisano, Danielle; Biddle, Amy; Mukherjee, Supratim; Ivanova, Natalia; Lykidis, Athanassios; Land, Miriam; Hauser, Loren; Kyrpides, Nikos; Henrissat, Bernard; Lau, Joanne; Schnell, Danny J; Church, George M; Leschine, Susan B; Blanchard, Jeffrey L

    2015-01-01

    Clostridium phytofermentans was isolated from forest soil and is distinguished by its capacity to directly ferment plant cell wall polysaccharides into ethanol as the primary product, suggesting that it possesses unusual catabolic pathways. The objective of the present study was to understand the molecular mechanisms of biomass conversion to ethanol in a single organism, Clostridium phytofermentans, by analyzing its complete genome and transcriptome during growth on plant carbohydrates. The saccharolytic versatility of C. phytofermentans is reflected in a diversity of genes encoding ATP-binding cassette sugar transporters and glycoside hydrolases, many of which may have been acquired through horizontal gene transfer. These genes are frequently organized as operons that may be controlled individually by the many transcriptional regulators identified in the genome. Preferential ethanol production may be due to high levels of expression of multiple ethanol dehydrogenases and additional pathways maximizing ethanol yield. The genome also encodes three different proteinaceous bacterial microcompartments with the capacity to compartmentalize pathways that divert fermentation intermediates to various products. These characteristics make C. phytofermentans an attractive resource for improving the efficiency and speed of biomass conversion to biofuels.

  17. Direct conversion of methane to C sub 2 's and liquid fuels

    SciTech Connect

    Warren, B.K.; Campbell, K.D.

    1989-11-22

    Objectives of the project are to discover and evaluate novel catalytic systems for the conversion of methane or by-product light hydrocarbon gases either indirectly (through intermediate light gases rich in C{sub 2}'s) or directly to liquid hydrocarbon fuels, and to evaluate, from an engineering perspective, different conceptualized schemes. The approach is to carry out catalyst testing on several specific classes of potential catalysts for the conversion of methane selectively to C{sub 2} products. Promoted metal oxide catalysts were tested. Several of these exhibited similar high ethylene to ethane ratios and low carbon dioxide to carbon monoxide ratios observed for the NaCl/{alpha}-alumina catalyst system reported earlier. Research on catalysts containing potentially activated metals began with testing of metal molecular sieves. Silver catalysts were shown to be promising as low temperature catalysts. Perovskites were tested as potential methane coupling catalysts. A layered perovskite (K{sub 2}La{sub 2}Ti{sub 3}O{sub 10}) gave the highest C{sub 2} yield. Work continued on the economic evaluation of a hypothetical process converting methane to ethylene. An engineering model of the methane coupling system has been prepared. 47 refs., 17 figs., 57 tabs.

  18. Direct solar-to-hydrogen conversion via inverted metamorphic multi-junction semiconductor architectures

    NASA Astrophysics Data System (ADS)

    Young, James L.; Steiner, Myles A.; Döscher, Henning; France, Ryan M.; Turner, John A.; Deutsch, Todd G.

    2017-03-01

    Solar water splitting via multi-junction semiconductor photoelectrochemical cells provides direct conversion of solar energy to stored chemical energy as hydrogen bonds. Economical hydrogen production demands high conversion efficiency to reduce balance-of-systems costs. For sufficient photovoltage, water-splitting efficiency is proportional to the device photocurrent, which can be tuned by judicious selection and integration of optimal semiconductor bandgaps. Here, we demonstrate highly efficient, immersed water-splitting electrodes enabled by inverted metamorphic epitaxy and a transparent graded buffer that allows the bandgap of each junction to be independently varied. Voltage losses at the electrolyte interface are reduced by 0.55 V over traditional, uniformly p-doped photocathodes by using a buried p-n junction. Advanced on-sun benchmarking, spectrally corrected and validated with incident photon-to-current efficiency, yields over 16% solar-to-hydrogen efficiency with GaInP/GaInAs tandem absorbers, representing a 60% improvement over the classical, high-efficiency tandem III-V device.

  19. Direct conversion of chitin biomass to 5-hydroxymethylfurfural in concentrated ZnCl2 aqueous solution.

    PubMed

    Wang, Yingxiong; Pedersen, Christian Marcus; Deng, Tiansheng; Qiao, Yan; Hou, Xianglin

    2013-09-01

    The direct conversion of chitin biomass to 5-hydroxymethylfurfural (5-HMF) in ZnCl2 aqueous solution was studied systemically. D-Glucosamine (GlcNH2) was chosen as the model compound to investigate the reaction, and 5-HMF could be obtained in 21.9% yield with 99% conversion of GlcNH2. Optimization of the reaction parameters including the screening of 8 co-catalysts was carried out. Among them, AlCl3 and B(OH)3 improved 5-HMF yield, whereas CdCl2, CuCl2 and NH4Cl had no effect. CrCl3, SnCl4 and SnCl2 showed negative effects, i.e. lower yields. Consequently, the optimal reaction conditions were found to be 67 wt.% ZnCl2 aqueous solution, at 120 °C without co-catalyst. The reactions were further studied by in situ NMR, and no intermediate or other byproducts, except humins, were observed. Finally, the substrate scope was expanded from GlcNH2 to N-acetyl-D-glucosamine and various chitosan polymers with different molecular weights, 5-HMF yield from polymers were generally lower than that from GlcNH2.

  20. Genome and Transcriptome of Clostridium phytofermentans, Catalyst for the Direct Conversion of Plant Feedstocks to Fuels

    SciTech Connect

    Petit, Elsa; Coppi, Maddalena V.; Hayes, James C.; Tolonen, Andrew C.; Warnick, Thomas; Latouf, William G.; Amisano, Danielle; Biddle, Amy; Mukherjee, Supratim; Ivanova, Natalia; Lykidis, Athanassios; Land, Miriam; Hauser, Loren; Kyrpides, Nikos; Henrissat, Bernard; Lau, Joanne; Schnell, Danny J.; Church, George M.; Leschine, Susan B.; Blanchard, Jeffrey L.

    2015-06-02

    Clostridium phytofermentans was isolated from forest soil and is distinguished by its capacity to directly ferment plant cell wall polysaccharides into ethanol as the primary product, suggesting that it possesses unusual catabolic pathways. The objective of our present study was to understand the molecular mechanisms of biomass conversion to ethanol in a single organism, Clostridium phytofermentans, by analyzing its complete genome and transcriptome during growth on plant carbohydrates. The saccharolytic versatility of C. phytofermentans is reflected in a diversity of genes encoding ATP-binding cassette sugar transporters and glycoside hydrolases, many of which may have been acquired through horizontal gene transfer. These genes are frequently organized as operons that may be controlled individually by the many transcriptional regulators identified in the genome. Preferential ethanol production may be due to high levels of expression of multiple ethanol dehydrogenases and additional pathways maximizing ethanol yield. The genome also encodes three different proteinaceous bacterial microcompartments with the capacity to compartmentalize pathways that divert fermentation intermediates to various products. Lastly, these characteristics make C. phytofermentans an attractive resource for improving the efficiency and speed of biomass conversion to biofuels.

  1. A broadband polarization-insensitive cloak based on mode conversion

    PubMed Central

    Gu, Chendong; Xu, Yadong; Li, Sucheng; Lu, Weixin; Li, Jensen; Chen, Huanyang; Hou, Bo

    2015-01-01

    In this work, we demonstrate an one-dimensional cloak consisting of parallel-plated waveguide with two slabs of gradient index metamaterials attached to its metallic walls. In it objects are hidden without limitation of polarizations, and good performance is observed for a broadband of frequencies. The experiments at microwave frequencies are carried out, supporting the theoretical results very well. The essential principle behind the proposed cloaking device is based on mode conversion, which provides a new strategy to manipulate wave propagation. PMID:26175114

  2. Test Results From a Direct Drive Gas Reactor Simulator Coupled to a Brayton Power Conversion Unit

    NASA Technical Reports Server (NTRS)

    Hervol, David S.; Briggs, Maxwell H.; Owen, Albert K.; Bragg-Sitton, Shannon M.

    2009-01-01

    The Brayton Power Conversion Unit (BPCU) located at NASA Glenn Research Center (GRC) in Cleveland, OH is a closed cycle system incorporating a turboaltemator, recuperator, and gas cooler connected by gas ducts to an external gas heater. For this series of tests, the BPCU was modified by replacing the gas heater with the Direct Drive Gas heater or DOG. The DOG uses electric resistance heaters to simulate a fast spectrum nuclear reactor similar to those proposed for space power applications. The combined system thermal transient behavior was the focus of these tests. The BPCU was operated at various steady state points. At each point it was subjected to transient changes involving shaft rotational speed or DOG electrical input. This paper outlines the changes made to the test unit and describes the testing that took place along with the test results.

  3. 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.

  4. 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.

  5. Direct conversion of radioactive and chemical waste containing metals, ceramics, amorphous solids, and organics to glass

    SciTech Connect

    Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

    1994-05-02

    The Glass Material Oxidation and Dissolution System (CMODS) is a new process for direct conversion of radioactive, mixed, and chemical wastes to glass. The wastes can be in the chemical forms of metals, ceramics, amorphous solids, and organics. GMODS destroys organics and it incorporates heavy metals and radionuclides into a glass. Processable wastes may include miscellaneous spent fuels (SF), SF hulls and hardware, plutonium wastes in different forms, high-efficiency particulate air (HEPA) filters, ion-exchange resins, failed equipment, and laboratory wastes. Thermodynamic calculations indicate theoretical feasibility. Small-scale laboratory experiments (< 100 g per test) have demonstrated chemical laboratory feasibility for several metals. Additional work is needed to demonstrate engineering feasibility.

  6. Defining the Minimal Factors Required for Erythropoiesis through Direct Lineage Conversion.

    PubMed

    Capellera-Garcia, Sandra; Pulecio, Julian; Dhulipala, Kishori; Siva, Kavitha; Rayon-Estrada, Violeta; Singbrant, Sofie; Sommarin, Mikael N E; Walkley, Carl R; Soneji, Shamit; Karlsson, Göran; Raya, Ángel; Sankaran, Vijay G; Flygare, Johan

    2016-06-14

    Erythroid cell commitment and differentiation proceed through activation of a lineage-restricted transcriptional network orchestrated by a group of well characterized genes. However, the minimal set of factors necessary for instructing red blood cell (RBC) development remains undefined. We employed a screen for transcription factors allowing direct lineage reprograming from fibroblasts to induced erythroid progenitors/precursors (iEPs). We show that Gata1, Tal1, Lmo2, and c-Myc (GTLM) can rapidly convert murine and human fibroblasts directly to iEPs. The transcriptional signature of murine iEPs resembled mainly that of primitive erythroid progenitors in the yolk sac, whereas addition of Klf1 or Myb to the GTLM cocktail resulted in iEPs with a more adult-type globin expression pattern. Our results demonstrate that direct lineage conversion is a suitable platform for defining and studying the core factors inducing the different waves of erythroid development. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  7. Near-Field and Far-Field Directional Conversion of Spoof Surface Plasmon Polaritons

    PubMed Central

    Tang, Heng-He; Tan, Yunhua; Liu, Pu-Kun

    2016-01-01

    A compact metallic meta-structure is proposed to realize directional conversion between spoof surface plasmon polaritons (SSPPs) and propagating waves at millimeter wave and THz frequencies. The structure is constructed by embedding two slits or multi-slits array into a subwavelength metallic reflection grating. When the back-side of the structure is illuminated by an oblique beam with a fixed incident angle, the propagating wave will be unidirectionally converted into SSPPs with a considerable efficiency. Both the simulations and experiments demonstrate that the excitation ratio of the SSPPs between the two possible propagating directions (left and right) reaches up to about 340. Furthermore, assisted by the structure, near-field SSPPs can be also converted into far-field narrow beams with particular directions. Through frequency sweeping, wide-angle beam scanning is verified by theory and experiments. The work paves a new way for SSPPs launching and also provides fresh ideas for super-resolution imaging in the longer wavelength range. PMID:27629825

  8. Near-Field and Far-Field Directional Conversion of Spoof Surface Plasmon Polaritons

    NASA Astrophysics Data System (ADS)

    Tang, Heng-He; Tan, Yunhua; Liu, Pu-Kun

    2016-09-01

    A compact metallic meta-structure is proposed to realize directional conversion between spoof surface plasmon polaritons (SSPPs) and propagating waves at millimeter wave and THz frequencies. The structure is constructed by embedding two slits or multi-slits array into a subwavelength metallic reflection grating. When the back-side of the structure is illuminated by an oblique beam with a fixed incident angle, the propagating wave will be unidirectionally converted into SSPPs with a considerable efficiency. Both the simulations and experiments demonstrate that the excitation ratio of the SSPPs between the two possible propagating directions (left and right) reaches up to about 340. Furthermore, assisted by the structure, near-field SSPPs can be also converted into far-field narrow beams with particular directions. Through frequency sweeping, wide-angle beam scanning is verified by theory and experiments. The work paves a new way for SSPPs launching and also provides fresh ideas for super-resolution imaging in the longer wavelength range.

  9. Near-Field and Far-Field Directional Conversion of Spoof Surface Plasmon Polaritons.

    PubMed

    Tang, Heng-He; Tan, Yunhua; Liu, Pu-Kun

    2016-09-15

    A compact metallic meta-structure is proposed to realize directional conversion between spoof surface plasmon polaritons (SSPPs) and propagating waves at millimeter wave and THz frequencies. The structure is constructed by embedding two slits or multi-slits array into a subwavelength metallic reflection grating. When the back-side of the structure is illuminated by an oblique beam with a fixed incident angle, the propagating wave will be unidirectionally converted into SSPPs with a considerable efficiency. Both the simulations and experiments demonstrate that the excitation ratio of the SSPPs between the two possible propagating directions (left and right) reaches up to about 340. Furthermore, assisted by the structure, near-field SSPPs can be also converted into far-field narrow beams with particular directions. Through frequency sweeping, wide-angle beam scanning is verified by theory and experiments. The work paves a new way for SSPPs launching and also provides fresh ideas for super-resolution imaging in the longer wavelength range.

  10. 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.

  11. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 5, November 16, 1987--January 15, 1988

    SciTech Connect

    Wilson, R.B. Jr.; Chan Yee Wai

    1988-02-05

    The goal of this research is to develop catalysts that directly convert methane and light hydrocarbons to intermediates that later can be converted to either liquid fuels or value-added chemicals, as economics dictate. During this reporting period, we have synthesized and tested several novel catalysts for methane reforming (Tasks 1 and 2) and for partial oxidation of methane (Tasks 3 and 4). We started to test a mixed metal system, an FeRu{sub 3} cluster. This catalyst was supported both on zeolite and on magnesium oxide and the systems were tested for methane reforming at various reaction temperatures. We also prepared and tested a monomeric ruthenium catalyst supported on magnesium oxide. We found that methane is activated at a lower temperature with the basic magnesium oxide support than with acidic supports such as zeolite or alumina. Methane conversions increased with temperature, but the production of coke also increased. We prepared a sterically hindered ruthenium porphyrin encapsulated in a zeolite supercage for catalysis of methane oxidation. The results showed that only carbon dioxide was produced. Addition of axial base to this catalyst gave similar results. Another type of catalyst, cobalt Schiff base complexes, was also prepared and tested for methane oxidation. In this case, no methane conversion was observed at temperatures ranging from 200 to 450{degrees}C. These complexes do not appear to be stable under the reaction conditions.

  12. Local community strategies for successful military base conversions

    SciTech Connect

    Yim, R.A.

    1994-12-31

    Military base closures are a paradox. On one hand, the scale and the rate of present base closures is unique historically. Since 1988, the US has closed 56 major military installations and over 60 minor facilities. Under the 1993 round of base closures, another 35 major installations and 95 smaller facilities nationwide were closed. Yet, for the most part, each base itself does not present unique problems. Common questions of environmental contamination remediation, infrastructure improvement, and reuse and redevelopment strategies are shared by each closing base. The challenge for the communities is to simultaneously recognize the uniqueness of the military base closure process, and adopt common but novel approaches to resolutions of the similar issues. Thus while the property disposal or economic development mechanisms which have historically been used may no longer be appropriate, new and innovative common strategies may be developed to expedite successful conversions. The purpose of this article is to examine the paradox presented by military base closures, to identify those outdated processes no longer appropriate for the unique nature of base closures, and to recommend innovative and common solutions to those issues found at all closing bases.

  13. Polarization conversion-based molecular sensing using anisotropic plasmonic metasurfaces

    NASA Astrophysics Data System (ADS)

    Verre, R.; Maccaferri, N.; Fleischer, K.; Svedendahl, M.; Odebo Länk, N.; Dmitriev, A.; Vavassori, P.; Shvets, I. V.; Käll, M.

    2016-05-01

    Anisotropic media induce changes in the polarization state of transmitted and reflected light. Here we combine this effect with the refractive index sensitivity typical of plasmonic nanoparticles to experimentally demonstrate self-referenced single wavelength refractometric sensing based on polarization conversion. We fabricated anisotropic plasmonic metasurfaces composed of gold dimers and, as a proof of principle, measured the changes in the rotation of light polarization induced by biomolecular adsorption with a surface sensitivity of 0.2 ng cm-2. We demonstrate the possibility of miniaturized sensing and we show that experimental results can be reproduced by analytical theory. Various ways to increase the sensitivity and applicability of the sensing scheme are discussed.Anisotropic media induce changes in the polarization state of transmitted and reflected light. Here we combine this effect with the refractive index sensitivity typical of plasmonic nanoparticles to experimentally demonstrate self-referenced single wavelength refractometric sensing based on polarization conversion. We fabricated anisotropic plasmonic metasurfaces composed of gold dimers and, as a proof of principle, measured the changes in the rotation of light polarization induced by biomolecular adsorption with a surface sensitivity of 0.2 ng cm-2. We demonstrate the possibility of miniaturized sensing and we show that experimental results can be reproduced by analytical theory. Various ways to increase the sensitivity and applicability of the sensing scheme are discussed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01336h

  14. Polymerization efficiency of curing lamps: a universal energy conversion relationship predictive of conversion of resin-based composite.

    PubMed

    Halvorson, Rolf H; Erickson, Robert L; Davidson, Carel L

    2004-01-01

    A universal energy-conversion relationship (ECRu) predictive of conversion of a resin-based composite (RBC) polymerized with any light source has been described. This relationship was derived from an energy conversion relationship for RBC polymerized with a tungsten-halogen lamp and the lamp's efficiency relative to a hypothetical standard lamp. The ECRu was then used to predict conversion throughout RBC polymerized with an LED lamp using the lamp's relative efficiency compared to the standard lamp. The universal energy scale has also been described as predictive of scrape-back lengths for this RBC family when polymerized with any light source. Despite a 31% greater relative efficiency, scrape-back lengths from RBC polymerized using the LED lamp were predicted to be only 6% greater than those polymerized with the tungsten-halogen lamp when RBC is polymerized on an equal energy basis. This result was experimentally verified.

  15. One-dimension-based spatially ordered architectures for solar energy conversion.

    PubMed

    Liu, Siqi; Tang, Zi-Rong; Sun, Yugang; Colmenares, Juan Carlos; Xu, Yi-Jun

    2015-08-07

    The severe consequences of fossil fuel consumption have resulted in a need for alternative sustainable sources of energy. Conversion and storage of solar energy via a renewable method, such as photocatalysis, holds great promise as such an alternative. One-dimensional (1D) nanostructures have gained attention in solar energy conversion because they have a long axis to absorb incident sunlight yet a short radial distance for separation of photogenerated charge carriers. In particular, well-ordered spatially high dimensional architectures based on 1D nanostructures with well-defined facets or anisotropic shapes offer an exciting opportunity for bridging the gap between 1D nanostructures and the micro and macro world, providing a platform for integration of nanostructures on a larger and more manageable scale into high-performance solar energy conversion applications. In this review, we focus on the progress of photocatalytic solar energy conversion over controlled one-dimension-based spatially ordered architecture hybrids. Assembly and classification of these novel architectures are summarized, and we discuss the opportunity and future direction of integration of 1D materials into high-dimensional, spatially organized architectures, with a perspective toward improved collective performance in various artificial photoredox applications.

  16. Photoelectrochemical based direct conversion systems for hydrogen production

    SciTech Connect

    Khaselev, O.; Bansal, A.; Kocha, S.; Turner, J.A.

    1998-08-01

    With an eye towards developing a photoelectrochemical system for hydrogen production using sunlight as the only energy input, two types of systems were studied, both involving multijunction devices. One set of cells consisted of a-Si triple junctions and the other a GaInP{sub 2}/GaAs tandem cell combination. Additional investigations were carried out on semiconductor surface modifications to move semiconductor band edges to more favorable energetic positions.

  17. Ultra-hard polycrystalline diamond synthesized by direct conversion of graphite using multianvil apparatus

    NASA Astrophysics Data System (ADS)

    Irifune, T.; Kurio, A.; Sakamoto, S.; Inoue, T.; Sumiya, H.

    2002-12-01

    Occurrence of sintered polycrystalline diamonds, such as carbonado and ballas, has been reported in some diamond mines, although the production rate has been very limited and their origin has been unsolved. These polycrystalline diamonds are most valuable in industrial applications because they are often harder than single crystal diamonds, whose hardness depends largely upon the crystallographic directions. Synthesis of pure polycrystalline diamond, however, has been unsuccessful, whereas single crystal diamond has been produced using some catalysts or solvents by high-pressure synthesis since its success in 1950's. Here, we report the first synthesis of a pure massive polycrystalline diamond by direct conversion of graphite without any catalysts/solvents under static high pressure and high temperature. Thus synthesized diamond at pressures 12-25 GPa and temperatures 2300-2500°C was optically transparent and colorless, and consisted of minute crystals of typically 1020 nanometers. Moreover, it was found that the Knoop hardness of the present diamonds is 110-140 GPa, which is higher than those of any known materials, including high quality synthetic type IIa diamond

  18. Direct energy conversion in fission reactors: A U.S. NERI project

    SciTech Connect

    SLUTZ,STEPHEN A.; SEIDEL,DAVID B.; POLANSKY,GARY F.; ROCHAU,GARY E.; LIPINSKI,RONALD J.; BESENBRUCH,G.; BROWN,L.C.; PARISH,T.A.; ANGHAIE,S.; BELLER,D.E.

    2000-05-30

    In principle, the energy released by a fission can be converted directly into electricity by using the charged fission fragments. The first theoretical treatment of direct energy conversion (DEC) appeared in the literature in 1957. Experiments were conducted over the next ten years, which identified a number of problem areas. Research declined by the late 1960's due to technical challenges that limited performance. Under the Nuclear Energy Research Initiative the authors are determining if these technical challenges can be overcome with todays technology. The authors present the basic principles of DEC reactors, review previous research, discuss problem areas in detail, and identify technological developments of the last 30 years that can overcome these obstacles. As an example, the fission electric cell must be insulated to avoid electrons crossing the cell. This insulation could be provided by a magnetic field as attempted in the early experiments. However, from work on magnetically insulated ion diodes they know how to significantly improve the field geometry. Finally, a prognosis for future development of DEC reactors will be presented .

  19. Mechanical motion conversion from reciprocating translation to one-directional rotation for effective energy harvesting

    NASA Astrophysics Data System (ADS)

    Ahmed, Kabir; Lee, Soobum

    2016-04-01

    This paper proposes a new efficient motion conversion system which can be used in an energy harvesting system that converts wasted kinematic energy into electrical energy. In the proposed system, a reciprocating translational motion will be converted into one-directional rotational motion that spins a generator. The system will be devised with a two overlapping chambers (chamber 1 and 2) which move relatively through the sliding joint, and a pair of flexible strings (belt, steel wire, or chain) run around the rotor of the generator. Each end of the string fixed to chamber 1 is designed not to interfere with chamber 2 where the generator is mounted. When the two chambers move relatively, either top or bottom string is tensioned to spin the rotor while the other string is being rewound. One-directional clutch with a coil spring is engaged in a rewinding system - as found in a rowing machine, for example - so each string actuates the rotor only when it is in tension. This device can be applied to any mechanism where reciprocating translational motion exists, such as linear suspension system in a vehicle, a bicycle, and an energy generating marine buoy. The experimental study result will be reported as well as its battery-charging capacity will be demonstrated.

  20. Direct conversion of theophylline to 3-methylxanthine by metabolically engineered E. coli.

    PubMed

    Algharrawi, Khalid H R; Summers, Ryan M; Gopishetty, Sridhar; Subramanian, Mani

    2015-12-21

    Methylxanthines are natural and synthetic compounds found in many foods, drinks, pharmaceuticals, and cosmetics. Aside from caffeine, production of many methylxanthines is currently performed by chemical synthesis. This process utilizes many chemicals, multiple reactions, and different reaction conditions, making it complicated, environmentally dissatisfactory, and expensive, especially for monomethylxanthines and paraxanthine. A microbial platform could provide an economical, environmentally friendly approach to produce these chemicals in large quantities. The recently discovered genes in our laboratory from Pseudomonas putida, ndmA, ndmB, and ndmD, provide an excellent starting point for precisely engineering Escherichia coli with various gene combinations to produce specific high-value paraxanthine and 1-, 3-, and 7-methylxanthines from any of the economical feedstocks including caffeine, theobromine or theophylline. Here, we show the first example of direct conversion of theophylline to 3-methylxanthine by a metabolically engineered strain of E. coli. Here we report the construction of E. coli strains with ndmA and ndmD, capable of producing 3-methylxanthine from exogenously fed theophylline. The strains were engineered with various dosages of the ndmA and ndmD genes, screened, and the best strain was selected for large-scale conversion of theophylline to 3-methylxanthine. Strain pDdA grown in super broth was the most efficient strain; 15 mg/mL cells produced 135 mg/L (0.81 mM) 3-methylxanthine from 1 mM theophylline. An additional 21.6 mg/L (0.13 mM) 1-methylxanthine were also produced, attributed to slight activity of NdmA at the N 3 -position of theophylline. The 1- and 3-methylxanthine products were separated by preparative chromatography with less than 5% loss during purification and were identical to commercially available standards. Purity of the isolated 3-methylxanthine was comparable to a commercially available standard, with no contaminant peaks as

  1. Direct MC conversion of absorbed dose to graphite to absorbed dose to water for 60Co radiation.

    PubMed

    Lye, J E; Butler, D J; Franich, R D; Harty, P D; Oliver, C P; Ramanathan, G; Webb, D V; Wright, T

    2013-06-01

    The ARPANSA calibration service for (60)Co gamma rays is based on a primary standard graphite calorimeter that measures absorbed dose to graphite. Measurements with the calorimeter are converted to the absorbed dose to water using the calculation of the ratio of the absorbed dose in the calorimeter to the absorbed dose in a water phantom. ARPANSA has recently changed the basis of this calculation from a photon fluence scaling method to a direct Monte Carlo (MC) calculation. The MC conversion uses an EGSnrc model of the cobalt source that has been validated against water tank and graphite phantom measurements, a step that is required to quantify uncertainties in the underlying interaction coefficients in the MC code. A comparison with the Bureau International des Poids et Mesures (BIPM) as part of the key comparison BIPM.RI(I)-K4 showed an agreement of 0.9973 (53).

  2. Toward direct light-to-digital conversion using a pulse-driven hybrid MOS-PN photodetector.

    PubMed

    Sallin, Denis; Koukab, Adil; Kayal, Maher

    2015-02-15

    In this Letter, a direct light-to-digital converter based on an MOS-PN photodetector driven by pulsed voltage is presented. The objective is to avoid any analog-to-digital or time-to-digital conversion and, thereby, to pave the way for a new generation of fully digital imaging sensors with reduced complexity, area, and power consumption. Moreover, the pulsed voltage operation allows for a significant reduction of the dark level. The concept is validated by a theoretical study and TCAD simulations. A first prototype fabricated in 0.18 μm CMOS technology is presented. The experimental results under various light conditions show that the pulsed voltage improves the light sensitivity by several orders of magnitude.

  3. Small molecule–driven direct conversion of human pluripotent stem cells into functional osteoblasts

    PubMed Central

    Kang, Heemin; Shih, Yu-Ru V.; Nakasaki, Manando; Kabra, Harsha; Varghese, Shyni

    2016-01-01

    The abilities of human pluripotent stem cells (hPSCs) to proliferate without phenotypic alteration and to differentiate into tissue-specific progeny make them a promising cell source for regenerative medicine and development of physiologically relevant in vitro platforms. Despite this potential, efficient conversion of hPSCs into tissue-specific cells still remains a challenge. Herein, we report direct conversion of hPSCs into functional osteoblasts through the use of adenosine, a naturally occurring nucleoside in the human body. The hPSCs treated with adenosine not only expressed the molecular signatures of osteoblasts but also produced calcified bone matrix. Our findings show that the adenosine-mediated osteogenesis of hPSCs involved the adenosine A2bR. When implanted in vivo, using macroporous synthetic matrices, the human induced pluripotent stem cell (hiPSC)–derived donor cells participated in the repair of critical-sized bone defects through the formation of neobone tissue without teratoma formation. The newly formed bone tissues exhibited various attributes of the native tissue, including vascularization and bone resorption. To our knowledge, this is the first demonstration of adenosine-induced differentiation of hPSCs into functional osteoblasts and their subsequent use to regenerate bone tissues in vivo. This approach that uses a physiologically relevant single small molecule to generate hPSC-derived progenitor cells is highly appealing because of its simplicity, cost-effectiveness, scalability, and impact in cell manufacturing, all of which are decisive factors for successful translational applications of hPSCs. PMID:27602403

  4. A GIS-based Model for Natural Gas Data Conversion

    NASA Astrophysics Data System (ADS)

    Bitik, E.; Seker, D. Z.; Denli, H. H.

    2014-12-01

    In Turkey gas utility sector has undergone major changes in terms of increased competition between gas providers, efforts in improving services, and applying new technological solutions. This paper discusses the challenges met by gas companies to switch from long workflows of gas distribution, sales and maintenance into IT driven efficient management of complex information both spatially and non-spatially. The aim of this study is migration of all gas data and information into a GIS environment in order to manage and operate all infrastructure investments with a Utility Management System. All data conversion model for migration was designed and tested during the study. A flowchart is formed to transfer the old data layers to the new structure based on geodatabase.

  5. Carbon-based electrocatalysts for advanced energy conversion and storage

    PubMed Central

    Zhang, Jintao; Xia, Zhenhai; Dai, Liming

    2015-01-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance. PMID:26601241

  6. Carbon-based electrocatalysts for advanced energy conversion and storage.

    PubMed

    Zhang, Jintao; Xia, Zhenhai; Dai, Liming

    2015-08-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance.

  7. Advanced power conversion based on the Aerocapacitor{trademark}

    SciTech Connect

    Josephs, L.C.; Gregory, D.; Roark, D.

    1997-10-01

    The authors report here, for the first time, high frequency testing of a new type of electrochemical double layer capacitor (EDLC), based on carbon aerogels: the Aerocapacitor. Carbon aerogels, are a novel type of carbon foam developed by Lawrence Livermore National Laboratory for military applications. The unique properties of carbon aerogels, high surface area (700 m{sup 2}/g), high density (1g/cc), well controlled pore diameter and high material conductivity (25 S/cm) made it an ideal EDLC electrode material. Using carbon aerogel as the electrode material, the authors have developed Aerocapacitors. These new EDLC`s have a frequency response comparable to that of aluminum electrolytic capacitors and are thus ideally suited to power conversion applications.

  8. Direct Conversion of Syngas-to-Hydrocarbons over Higher Alcohols Synthesis Catalysts Mixed with HZSM-5

    SciTech Connect

    Lebarbier Dagel, Vanessa M.; Dagle, Robert A.; Li, Jinjing; Deshmane, Chinmay A.; Taylor, Charles E.; Bao, Xinhe; Wang, Yong

    2014-09-10

    The synthesis of hydrocarbon fuels directly from synthesis gas (i.e. one step process) was investigated with a catalytic system comprised of HZSM-5 physically mixed with either a methanol synthesis catalyst or a higher alcohols synthesis (HAS) catalyst. The metal sites of the methanol or HAS synthesis catalyst enable the conversion of syngas to alcohols, whereas HZSM-5 provides acid sites required for methanol dehydration, and dimethyl ether-to-hydrocarbons reactions. Catalytic performance for HZSM-5 when mixed with either a 5 wt.% Pd/ZnO/Al2O3 methanol synthesis catalyst or a HAS catalyst was evaluated at 300°C, 70 bars, GHSV=700 h-1 and H2/CO=1 using a HZSM-5: alcohols synthesis catalyst weight ratio of 3:1. The major difference observed between the methanol synthesis and HAS catalyst mixtures was found in the production of durene which is an undesirable byproduct. While durene formation is negligible with any of the HAS catalysts mixed with the HZSM-5 evaluated in this study, it represents almost 50% of the C5+ fraction for the methanol synthesis catalyst (5 wt.% Pd/ZnO/Al2O3 ) mixed with HZSM-5. This presents an advantage for using HAS catalysts over the methanol synthesis catalyst to minimize the durene by-product. The yield toward the desired C5+ hydrocarbons is thus twice higher with selected HAS catalysts as compared to when HZSM-5 is mixed with 5 wt.% Pd/ZnO/Al2O3. Among all the HAS catalysts evaluated in this study, a catalyst with 0.5 wt.% Pd/FeCoCu catalyst was found the most promising due to higher production of C5+ hydrocarbons and low durene formation. The efficiency of the one-step process was thus further evaluated using the HZSM-5: 0.5 wt.% Pd/FeCoCu catalyst mixture under a number of process conditions to maximize liquid hydrocarbons product yield. At 300oC, 70 bars, GHSV = 700 h-1 and HZSM-5: 0.5 wt.% Pd/FeCoCu = 3:1 (wt.), the C5+ fraction represents 48.5% of the hydrocarbons. Unfortunately, it is more difficult to achieve higher selectivity

  9. A direct pathway for the conversion of propionate into pyruvate in Moraxella lwoffi

    PubMed Central

    Hodgson, B.; McGarry, J. D.

    1968-01-01

    1. The identity of the organism previously known as Vibrio O1 (N.C.I.B. 8250) with a species of Moraxella is established. 2. The ability of cells to oxidize propionate is present only in cells with an endogenous respiration and this ability is increased 80-fold when the organism is grown with propionate. 3. Isocitrate lyase activity in extracts from propionate-grown cells is the same as that in extracts from lactate-grown cells, about tenfold greater than that in extracts from succinate-grown cells and slightly greater than half the activity in extracts from acetate-grown cells. 4. With arsenite as an inhibitor conditions were found in which the organism would catalyse the quantitative oxidation of propionate to pyruvate. When propionate was completely utilized pyruvate was metabolized further to 2-oxoglutarate. 5. The oxidation of propionate by cells was incomplete both in a `closed system' with alkali to trap respiratory carbon dioxide and in an `open system' with an atmosphere of oxygen+carbon dioxide (95:5). Acetate accumulated. Under these conditions [2-14C]- and [3-14C]-propionate gave rise to [14C]acetate. The rate of conversion of [2-14C]propionate into 14CO2, although much less than the rate of conversion of [1-14C]propionate into 14CO2, was slightly greater than the rate of conversion of [3-14C]propionate into 14CO2. 6. The oxidation of propionate by cells was complete in an `open system' with an atmosphere of either oxygen or air. Under these conditions very little [1-14C]propionate was converted into 14C-labelled cell material. The conversion of [2-14C]- and [3-14C]-propionate into 14C-labelled cell material occurred at an appreciable rate, the rate for the incorporation of [3-14C]propionate being slightly more rapid. In the absence of a utilizable nitrogen source part of the [14C]propionate was incorporated into some reserve material, which was oxidized when added substrate had been completely utilized. 7. [14C]-Pyruvate produced from [14C

  10. Simulation and Experimental Study on the Efficiency of Traveling Wave Direct Energy Conversion for Application to Aneutronic Fusion Reactions

    NASA Astrophysics Data System (ADS)

    Tarditi, Alfonso; Chap, Andrew; Miley, George; Scott, John

    2013-10-01

    A study based on both Particle-in-cell (PIC) simulation and experiments is being developed to study the physics of the Traveling Wave Direct Energy Converter (TWDEC,) with the perspective of application to aneutronic fusion reaction products and space propulsion. The PIC model is investigating in detail the key TWDEC physics process by simulating the time-dependent transfer of energy from the ion beam to an electric load connected to ring-type electrodes in cylindrical symmetry. An experimental effort is in progress on a TWDEC test article at NASA, Johnson Space Center with the purpose of studying the conditions for improving the efficiency of the direct energy conversion process. Using a scaled-down ion energy source, the experiment is primarily focused on the effect of the (bunched) beam density on the efficiency and on the optimization of the electrode design. The simulation model is guiding the development of the experimental configuration and will provide details of the beam dynamics for direct comparison with experimental diagnostics. Work supported by NASA, Johnson Space Center.

  11. Visual markers for detecting gene conversion directly in the gametes of Arabidopsis thaliana.

    PubMed

    Berchowitz, Luke E; Copenhaver, Gregory P

    2009-01-01

    Measuring meiotic gene conversion is important both because of its role in the fundamental mechanisms of meiotic recombination and because of its influence on linkage relationships and allelic diversity in the genome. Historically, gene conversion has been most thoroughly examined in fungal organisms through the use of tetrad analysis. Here we describe a method for using tetrad analysis in the model plant Arabidopsis thaliana to detect and quantify gene conversion events - a resource unavailable in most other higher eukaryotic model systems.

  12. Complex Nanostructures from Materials based on Metal-Organic Frameworks for Electrochemical Energy Storage and Conversion.

    PubMed

    Guan, Bu Yuan; Yu, Xin Yao; Wu, Hao Bin; Lou, Xiong Wen David

    2017-09-27

    Metal-organic frameworks (MOFs) have drawn tremendous attention because of their abundant diversity in structure and composition. Recently, there has been growing research interest in deriving advanced nanomaterials with complex architectures and tailored chemical compositions from MOF-based precursors for electrochemical energy storage and conversion. Here, a comprehensive overview of the synthesis and energy-related applications of complex nanostructures derived from MOF-based precursors is provided. After a brief summary of synthetic methods of MOF-based templates and their conversion to desirable nanostructures, delicate designs and preparation of complex architectures from MOFs or their composites are described in detail, including porous structures, single-shelled hollow structures, and multishelled hollow structures, as well as other unusual complex structures. Afterward, their applications are discussed as electrode materials or catalysts for lithium-ion batteries, hybrid supercapacitors, water-splitting devices, and fuel cells. Lastly, the research challenges and possible development directions of complex nanostructures derived from MOF-based-templates for electrochemical energy storage and conversion applications are outlined. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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.

  14. Low power considerations and design for CMOS VCOs applied for direct conversion receivers at 5GHz

    NASA Astrophysics Data System (ADS)

    Adin, Iñigo; Quemada, Carlos; Solar, Hector; Sedano, Beatriz; Gutierrez, Iñigo

    2007-05-01

    Low power design often requires direct conversion architectures, such as low-IF or zero-IF. Any of these two possibilities needs a low power, low phase noise voltage control oscillator (VCO) in the frequency synthesizer. This work is focused on low power considerations applied to the practical modern conception of this device. Fulfilling the standard specifications (output power, phase noise, frequency range) should be completed with this deeper step. A conscious design leads moreover to an improvement in the results obtained by the classical considerations. The increase of the quality factor of the passive elements is one of the key points, followed by an accurate design of the architecture scheme. Furthermore, lower current consumption provides higher oscillation frequencies and facilitates higher frequency ranges, which follow the trends of modern wireless and wideband communication standards. In order to validate the aforementioned assumptions, a CMOS VCO has been implemented in UMC 0.18μm 1P6M technology, with power consumption down to 3.4mW.

  15. Direct Energy Conversion for Low Specific Mass In-Space Power and Propulsion

    NASA Technical Reports Server (NTRS)

    Scott, John H.; George, Jeffrey A.; Tarditi, Alfonso G.

    2013-01-01

    "Changing the game" in space exploration involves changing the paradigm for the human exploration of the Solar System, e.g, changing the human exploration of Mars from a three-year epic event to an annual expedition. For the purposes of this assessment an "annual expedition" capability is defined as an in-space power & propulsion system which, with launch mass limits as defined in NASA s Mars Architecture 5.0, enables sending a crew to Mars and returning them after a 30-day surface stay within one year, irrespective of planetary alignment. In this work the authors intend to show that obtaining this capability requires the development of an in-space power & propulsion system with an end-to-end specific mass considerably less than 3 kg/kWe. A first order energy balance analysis reveals that the technologies required to create a system with this specific mass include direct energy conversion and nuclear sources that release energy in the form of charged particle beams. This paper lays out this first order approximation and details these conclusions.

  16. Conversion of solar energy into electricity by using duckweed in Direct Photosynthetic Plant Fuel Cell.

    PubMed

    Hubenova, Yolina; Mitov, Mario

    2012-10-01

    In the present study we demonstrate for the first time the possibility for conversion of solar energy into electricity on the principles of Direct Photosynthetic Plant Fuel Cell (DPPFC) technology by using aquatic higher plants. Lemna minuta duckweed was grown autotrophically in specially constructed fuel cells under sunlight irradiation and laboratory lighting. Current and power density up to 1.62±0.10 A.m(-2) and 380±19 mW.m(-2), respectively, were achieved under sunlight conditions. The influence of the temperature, light intensity and day/night sequencing on the current generation was investigated. The importance of the light intensity was demonstrated by the higher values of generated current (at permanently connected resistance) during daytime than those through the nights, indicating the participation of light-dependent photosynthetic processes. The obtained DPPFC outputs in the night show the contribution of light-independent reactions (respiration). The electron transfer in the examined DPPFCs is associated with a production of endogenous mediator, secreted by the duckweed. The plants' adaptive response to the applied polarization is also connected with an enhanced metabolism resulting in an increase of the protein and carbohydrate intracellular content. Further investigations aiming at improvement of the DPPFC outputs and elucidation of the electron transfer mechanism are required for practical application. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Electrophysiological Profiles of Induced Neurons Converted Directly from Adult Human Fibroblasts Indicate Incomplete Neuronal Conversion

    PubMed Central

    Koppensteiner, Peter; Boehm, Stefan

    2014-01-01

    Abstract The direct conversion of human fibroblasts to neuronal cells, termed human induced neuronal (hiN) cells, has great potential for future clinical advances. However, previous studies have not provided an in-depth analysis of electrophysiological properties of adult fibroblast-derived hiN cultures. We have examined the electrophysiological profile of hiN cells by measuring passive and active membrane properties, as well as spontaneous and evoked neurotransmission. We found that hiN cells exhibited passive membrane properties equivalent to perinatal rodent neurons. In addition, 30% of hiN cells were incapable of action potential (AP) generation and did not exhibit rectifying membrane currents, and none of the cells displayed firing patterns of typical glutamatergic pyramidal neurons. Finally, hiN cells exhibited neither spontaneous nor evoked neurotransmission. Our results suggest that current methods used to produce hiN cells provide preparations in which cells do not achieve the cellular properties of fully mature neurons, rendering these cells inadequate to investigate pathophysiological mechanisms. PMID:25437871

  18. Bacterial production and carbon conversion based on saltmarsh plant debris

    NASA Astrophysics Data System (ADS)

    Newell, R. C.; Linley, E. A. S.; Lucas, M. I.

    1983-10-01

    There is a well-defined succession of micro-organisms which colonize powdered leaf debris from Spartina alterniflora and Juncus roemerianus, and aged natural detrital material when these were incubated in estuarine water at temperatures near to those recorded in the habitat at the time of collection. The natural assemblage of free-living bacteria in estuarine water rapidly enters logarithmic growth, subsequently declining with the increase in numbers of bactivorous microflagellates. These are then replaced by a mixed population of ciliates, choanoflagellates, amoeboid forms and attached bacteria which form part of a complex microbial community associated with particulate debris. The rate of increase of bacterial cells (μ), in both spring and summer experiments ranged from 0·010-0·108 h -1 whilst estimates of bacterial carbon production ranged from 1·5 to 10·1 μg C 1 -1 h -1, values which conform well with estimates obtained from natural assemblages of marine bacteria in coastal and estuarine waters elsewhere. Although both the ease of degradation of the detrital substrate and incubation temperature are of importance, enrichment of both powdered Spartina leaf debris and aged natural detritus with inorganic nutrients evidently enhances bacterial production under experimental conditions. In addition, the amount of carbon utilized to sustain bacterial carbon production shows a significant reduction following enrichment with NH 4, NO 3 or combinations of NO 3 + PO 4. The bacterial carbon conversion efficiency (μg C incorporated into bacterial production per μg C consumed) × 100, based on powdered Spartina leaves, and aged natural detritus, is thus increased from 9-14%, to as much as 38% in nutrient enriched media. Since NH 4, NO 3 and PO 4 values are generally low in the water column, it seems likely that bacteria achieve a carbon conversion of only 9-14% on natural suspended detrital material, with the possibility of an enhanced conversion of up to 38

  19. On the effect of polarization direction on the converse magnetoelectric response of multiferroic composite rings

    NASA Astrophysics Data System (ADS)

    Youssef, George; Lopez, Mario; Newacheck, Scott

    2017-03-01

    The application domain of composite multiferroic materials with magnetoelectric coupling has been widening on the nano-, micro- and macro-scales. Generally, a composite multiferroic material consists of two, or more, layers of a piezoelectric material and a magnetostrictive material. In turn, the proliferation of multiferroics in more applications is accompanied by a keen focus on understanding the effect of material phases, geometry, bonding interface and arrangement of phases by performing theoretical, numerical and experimental studies to fundamentally elucidate the response. In this experimental study, a focus is given to exploit the effect of the polarization direction of the piezoelectric phase on the overall converse magnetoelectric (CME) response of a composite concentric PZT/Terfenol-D structure. Specifically, radially and axially polarized PZT rings were concentrically bonded to the outer surface of two Terfenol-D rings, respectively. It was found that the maximum, near resonance, CME coefficient of the axially-poled configuration is 443 mG V‑1 when tested at 34 kHz, 80 kV m‑1 electric field and 784 Oe bias magnetic field. On the other hand, the near resonance CME value for the radially-poled configuration remained nearly constant at 281.9 ± 5.3 mG V‑1 between bias magnetic fields of 532 Oe and 1524 Oe at AC electric field of 80 kV m‑1 with a frequency of 36 kHz. Interestingly, the CME coefficient of radially-poled composite structure exhibits a saturation behavior, while the CME coefficient for axially-poled structure is distinguished by a single peak. The difference in the response is attributed to the amount strain transduction due to the polarization direction.

  20. Direct xylan conversion into glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma antarctica PYCC 5048(T).

    PubMed

    Faria, Nuno Torres; Marques, Susana; Fonseca, César; Ferreira, Frederico Castelo

    2015-04-01

    Mannosylerythritol lipids (MEL) are glycolipid biosurfactants, produced by Pseudozyma spp., with increasing commercial interest. While MEL can be produced from d-glucose and d-xylose, the direct conversion of the respective lignocellulosic polysaccharides, cellulose and xylan, was not reported yet. The ability of Pseudozyma antarctica PYCC 5048(T) and Pseudozyma aphidis PYCC 5535(T) to use cellulose (Avicel(®)) and xylan (beechwood) as carbon and energy source has been assessed along with their capacity of producing cellulolytic and hemicellulolytic enzymes, toward a consolidated bioprocess (CBP) for MEL production. The yeasts assessed were neither able to grow in medium containing Avicel(®) nor produce cellulolytic enzymes under the conditions tested. On contrary, both yeasts were able to efficiently grow in xylan, but MEL production was only detected in P. antarctica PYCC 5048(T) cultures. MEL titers reached 1.3g/l after 10 days in batch cultures with 40g/l xylan, and 2.0g/l in fed-batch cultures with xylan feeding (additional 40g/l) at day 4. High levels of xylanase activities were detected in xylan cultures, reaching 47-62U/ml (31-32U/mg) at 50°C, and still exhibiting more than 10U/ml under physiological temperature (28°C). Total β-xylosidase activities, displayed mainly as wall-bounded and extracellular activity, accounted for 0.154 and 0.176U/ml in P. antarctica PYCC 5048(T) and P. aphidis PYCC 5535(T) cultures, respectively. The present results demonstrate the potential of Pseudozyma spp. for using directly a fraction of lignocellulosic biomass, xylan, and combining in the same bioprocess the production of xylanolytic enzymes with MEL production.

  1. NGL data conversion system

    NASA Astrophysics Data System (ADS)

    Shoji, Masahiro; Horiuchi, Nobuyasu

    2005-06-01

    We are developing a NGL data conversion system for EPL, for LEEPL, and for EBDW, which is based on our established photomask data conversion system, PATACON PC-cluster. For EPL data conversion, it has SF division, Complementary division, Stitching, Proximity effect correction, Alignment mark insertion, EB stepper control data creation, and Mask inspection data creation. For LEEPL data conversion, it has Pattern checking, Complementary division, Stitching, Stress distortion correction, Alignment mark insertion, and Mask inspection data creation. For EB direct-writing data conversion, it has Proximity effect correction and Extraction of aperture pattern for cell projection exposure.

  2. Enhanced photovoltaic energy conversion using thermally based spectral shaping

    NASA Astrophysics Data System (ADS)

    Bierman, David M.; Lenert, Andrej; Chan, Walker R.; Bhatia, Bikram; Celanović, Ivan; Soljačić, Marin; Wang, Evelyn N.

    2016-06-01

    Solar thermophotovoltaic devices have the potential to enhance the performance of solar energy harvesting by converting broadband sunlight to narrow-band thermal radiation tuned for a photovoltaic cell. A direct comparison of the operation of a photovoltaic with and without a spectral converter is the most critical indicator of the promise of this technology. Here, we demonstrate enhanced device performance through the suppression of 80% of unconvertible photons by pairing a one-dimensional photonic crystal selective emitter with a tandem plasma-interference optical filter. We measured a solar-to-electrical conversion rate of 6.8%, exceeding the performance of the photovoltaic cell alone. The device operates more efficiently while reducing the heat generation rates in the photovoltaic cell by a factor of two at matching output power densities. We determined the theoretical limits, and discuss the implications of surpassing the Shockley-Queisser limit. Improving the performance of an unaltered photovoltaic cell provides an important framework for the design of high-efficiency solar energy converters.

  3. Photonic analog-to-digital conversion based on oversampling techniques

    NASA Astrophysics Data System (ADS)

    Shoop, Barry L.; Das, Pankaj K.; Ressler, Eugene K., Jr.; Talty, Timothy J.

    2000-07-01

    A novel photonic approach to analog-to-digital (A/D) conversion based on temporal and spatial oversampling techniques in conjunction with a smart pixel hardware implementation of a neural algorithm is described. In this approach, the input signal is first sampled at a rate higher than that required by the Nyquist criterion and then presented spatially as the input to the 2D error diffusion neural network consisting of M X N pixels. The neural network processes the input oversampled analog image and produces an M X N pixel binary output image which is an optimum representation of the input analog signal. Upon convergence, the neural network minimizes an energy function representing the frequency-weighted squared error between the input analog image and the output halftoned image. Decimation and low-pass filtering techniques, common to oversampling A/D converters, digitally sum and average the M X N pixel output binary image using high-speed digital electronic circuitry. By employing a 2D smart pixel neural approach to oversampling A/D conversion, each pixel constitutes a simple oversampling modulator thereby producing a distributed A/D architecture. Spectral noise shaping across the array diffuses quantization error thereby improving the signal-to-noise ratio performance. Here, each quantizer within the network is embedded in a fully- connected, distributed mesh feedback loop which spectrally shapes the overall quantization noise significantly reducing the effects of component mismatch typically associated with parallel or channelized A/D approaches. The 2D neural array provides higher aggregate bit rates which can extend the useful bandwidth of oversampling converters.

  4. HNO/NO Conversion Mechanisms of Cu-Based HNO Probes with Implications for Cu,Zn-SOD

    PubMed Central

    2015-01-01

    HNO has broad biological effects and pharmacological activities. Direct HNO probes for in vivo applications were recently reported, which are CuII-based complexes having fluorescence reporters with reaction to HNO resulting in CuI systems and the release of NO. Their coordination environments are similar to that in Cu,Zn-superoxide dismutase (SOD), which plays a significant role in cellular HNO/NO conversion. However, none of these conversion mechanisms are known. A quantum chemical investigation was performed here to provide structural, energetic, and electronic profiles of HNO/NO conversion pathways via the first CuII-based direct HNO probe. Results not only are consistent with experimental observations but also provide numerous structural and mechanistic details unknown before. Results also suggest the first HNO/NO conversion mechanism for Cu,Zn-SOD, as well as useful guidelines for future design of metal-based HNO probes. These results shall facilitate development of direct HNO probes and studies of HNO/NO conversions via metal complexes and metalloproteins. PMID:24803995

  5. Developmental Pragmatics: Linguistic and Extralinguistic Bases of Early Conversations.

    ERIC Educational Resources Information Center

    Luszcz, M. A.; Bacharach, V. R.

    The inferential use of linguistic and extralinguistic information in structuring conversations was studied in 90 three- and five-year-old children. Pictures portraying an actor-action-object relation, e.g., a child picking a flower, were used to guide conversational sequences. Both active pictures (which emphasized an action relating actor and…

  6. Direct observation and modelling of ordered hydrogen adsorption and catalyzed ortho-para conversion on ETS-10 titanosilicate material.

    PubMed

    Ricchiardi, Gabriele; Vitillo, Jenny G; Cocina, Donato; Gribov, Evgueni N; Zecchina, Adriano

    2007-06-07

    Hydrogen physisorption on porous high surface materials is investigated for the purpose of hydrogen storage and hydrogen separation, because of its simplicity and intrinsic reversibility. For these purposes, the understanding of the binding of dihydrogen to materials, of the structure of the adsorbed phase and of the ortho-para conversion during thermal and pressure cycles are crucial for the development of new hydrogen adsorbents. We report the direct observation by IR spectroscopic methods of structured hydrogen adsorption on a porous titanosilicate (ETS-10), with resolution of the kinetics of the ortho-para transition, and an interpretation of the structure of the adsorbed phase based on classical atomistic simulations. Distinct infrared signals of o- and p-H2 in different adsorbed states are measured, and the conversion of o- to p-H2 is monitored over a timescale of hours, indicating the presence of a catalyzed reaction. Hydrogen adsorption occurs in three different regimes characterized by well separated IR manifestations: at low pressures ordered 1:1 adducts with Na and K ions exposed in the channels of the material are formed, which gradually convert into ordered 2:1 adducts. Further addition of H2 occurs only through the formation of a disordered condensed phase. The binding enthalpy of the Na+-H2 1:1 adduct is of -8.7+/-0.1 kJ mol(-1), as measured spectroscopically. Modeling of the weak interaction of H2 with the materials requires an accurate force field with a precise description of both dispersion and electrostatics. A novel three body force field for molecular hydrogen is presented, based on the fitting of an accurate PES for the H2-H2 interaction to the experimental dipole polarizability and quadrupole moment. Molecular mechanics simulations of hydrogen adsorption at different coverages confirm the three regimes of adsorption and the structure of the adsorbed phase.

  7. X-ray-to-current signal conversion characteristics of trench-structured photodiodes for direct-conversion-type silicon X-ray sensor

    NASA Astrophysics Data System (ADS)

    Ariyoshi, Tetsuya; Funaki, Shota; Sakamoto, Kenji; Baba, Akiyoshi; Arima, Yutaka

    2017-04-01

    To reduce the radiation dose required in medical X-ray diagnoses, we propose a high-sensitivity direct-conversion-type silicon X-ray sensor that uses trench-structured photodiodes. This sensor is advantageous in terms of its long device lifetime, noise immunity, and low power consumption because of its low bias voltage. With this sensor, it is possible to detect X-rays with almost 100% efficiency; sensitivity can therefore be improved by approximately 10 times when compared with conventional indirect-conversion-type sensors. In this study, a test chip was fabricated using a single-poly single-metal 0.35 µm process. The formed trench photodiodes for the X-ray sensor were approximately 170 and 300 µm deep. At a bias voltage of 25 V, the absorbed X-ray-to-current signal conversion efficiencies were 89.3% (theoretical limit; 96.7%) at a trench depth of 170 µm and 91.1% (theoretical limit; 94.3%) at a trench depth of 300 µm.

  8. Predicting Social Anxiety Treatment Outcome Based on Therapeutic Email Conversations.

    PubMed

    Hoogendoorn, Mark; Berger, Thomas; Schulz, Ava; Stolz, Timo; Szolovits, Peter

    2017-09-01

    Predicting therapeutic outcome in the mental health domain is of utmost importance to enable therapists to provide the most effective treatment to a patient. Using information from the writings of a patient can potentially be a valuable source of information, especially now that more and more treatments involve computer-based exercises or electronic conversations between patient and therapist. In this paper, we study predictive modeling using writings of patients under treatment for a social anxiety disorder. We extract a wealth of information from the text written by patients including their usage of words, the topics they talk about, the sentiment of the messages, and the style of writing. In addition, we study trends over time with respect to those measures. We then apply machine learning algorithms to generate the predictive models. Based on a dataset of 69 patients, we are able to show that we can predict therapy outcome with an area under the curve of 0.83 halfway through the therapy and with a precision of 0.78 when using the full data (i.e., the entire treatment period). Due to the limited number of participants, it is hard to generalize the results, but they do show great potential in this type of information.

  9. 5 CFR 892.303 - Can I pay my premiums directly by check under the premium conversion plan?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Can I pay my premiums directly by check under the premium conversion plan? 892.303 Section 892.303 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL FLEXIBLE BENEFITS PLAN: PRE-TAX PAYMENT...

  10. 5 CFR 892.303 - Can I pay my premiums directly by check under the premium conversion plan?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Can I pay my premiums directly by check under the premium conversion plan? 892.303 Section 892.303 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL FLEXIBLE BENEFITS PLAN: PRE-TAX PAYMENT...

  11. A novel approach for using polyphase filter bank in directly digital RF conversion from RF to baseband

    NASA Astrophysics Data System (ADS)

    Zhang, Deying; Jiang, Qin; Ahmed, Mohiuddin

    2012-05-01

    Software defined radio (SDR) hardware platform is in high demand for ultra-wideband digital EW receiver to carry out different mission requirements. Due to the limitations of current Analog-to-Digital conversion (ADC) techniques, the ideal receiver structure of SDR, with digital RF frequency conversion, cannot be achieved. In this article, a new channelization technique called ADC polyphase fast Fourier transformation (ADC PFFT) filter bank channelization is demonstrated. The key concept is to separate the speed at which the two functional units of an ADC - the sample and hold and the quantizer - operate. The sample and hold unit operates at the sampling frequency fs and the quantizer (the speed limiting factor in ADCs) can operate at a much slower rate, fs/M, where M is the decimation factor for digital filter bank. By integrated this ADC PFFT technique in ultra-wideband digital channelized EW receivers, directly digital RF down conversion can be achieved. With the ADC PFFT channelization for RF down conversion and polyphase FFT channelization for IF down conversion, 2-18 GHz frequency coverage can be accomplished in such ultra-wideband digital channelized EW receivers without the requirement of EW receivers being time-shared among outputs from many subbands due to bandwidth limitation in digital IF channelized EW receivers. Because the frequency down conversion from RF to BB are all processed digitally, issues such as image rejection and I/Q imbalance due to analog mixing will be eliminated in the ultrawideband digital channelized EW receivers.

  12. ForConX: A forcefield conversion tool based on XML.

    PubMed

    Lesch, Volker; Diddens, Diddo; Bernardes, Carlos E S; Golub, Benjamin; Dequidt, Alain; Zeindlhofer, Veronika; Sega, Marcello; Schröder, Christian

    2017-04-05

    The force field conversion from one MD program to another one is exhausting and error-prone. Although single conversion tools from one MD program to another exist not every combination and both directions of conversion are available for the favorite MD programs Amber, Charmm, Dl-Poly, Gromacs, and Lammps. We present here a general tool for the force field conversion on the basis of an XML document. The force field is converted to and from this XML structure facilitating the implementation of new MD programs for the conversion. Furthermore, the XML structure is human readable and can be manipulated before continuing the conversion. We report, as testcases, the conversions of topologies for acetonitrile, dimethylformamide, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate comprising also Urey-Bradley and Ryckaert-Bellemans potentials. © 2017 Wiley Periodicals, Inc.

  13. Energy conversion performance of black liquor gasification to hydrogen production using direct causticization with CO(2) capture.

    PubMed

    Naqvi, M; Yan, J; Dahlquist, E

    2012-04-01

    This paper estimates potential hydrogen production via dry black liquor gasification system with direct causticization integrated with a reference pulp mill. The advantage of using direct causticization is elimination of energy intensive lime kiln. Pressure swing adsorption is integrated in the carbon capture process for hydrogen upgrading. The energy conversion performance of the integrated system is compared with other bio-fuel alternatives and evaluated based on system performance indicators. The results indicated a significant hydrogen production potential (about 141MW) with an energy ratio of about 0.74 from the reference black liquor capacity (about 243.5MW) and extra biomass import (about 50MW) to compensate total energy deficit. About 867,000tonnes of CO(2) abatement per year is estimated i.e. combining CO(2) capture and CO(2) offset from hydrogen replacing motor gasoline. The hydrogen production offers a substantial motor fuel replacement especially in regions with large pulp and paper industry e.g. about 63% of domestic gasoline replacement in Sweden.

  14. On the rejection of internal and external disturbances in a wind energy conversion system with direct-driven PMSG.

    PubMed

    Li, Shengquan; Zhang, Kezhao; Li, Juan; Liu, Chao

    2016-03-01

    This paper deals with the critical issue in a wind energy conversion system (WECS) based on a direct-driven permanent magnet synchronous generator (PMSG): the rejection of lumped disturbance, including the system uncertainties in the internal dynamics and unknown external forces. To simultaneously track the motor speed in real time and capture the maximum power, a maximum power point tracking strategy is proposed based on active disturbance rejection control (ADRC) theory. In real application, system inertia, drive torque and some other parameters change in a wide range with the variations of disturbances and wind speeds, which substantially degrade the performance of WECS. The ADRC design must incorporate the available model information into an extended state observer (ESO) to compensate the lumped disturbance efficiently. Based on this principle, a model-compensation ADRC is proposed in this paper. Simulation study is conducted to evaluate the performance of the proposed control strategy. It is shown that the effect of lumped disturbance is compensated in a more effective way compared with the traditional ADRC approach.

  15. An energy conversion relationship predictive of conversion profiles and depth of cure for resin-based composite.

    PubMed

    Halvorson, Rolf H; Erickson, Robert L; Davidson, Carel L

    2003-01-01

    Predicting the polymerization throughout resin-based composite (RBC) has been reduced to a set of variables involving irradiance of the light source, exposure duration and RBC transmission properties, together with an energy-conversion relationship (ECR) derived from Fourier Transform Infrared Spectroscopic analysis (FTIR) of a single shade of photo-polymerized RBC. The ECR describes the localized energy density required to achieve a desired conversion independent of shade. Using this ECR, conversion was predicted and experimentally verified throughout different opacities of RBC based on knowledge of their transmission properties and the incident radiant energy density (irradiance times exposure time). Also, using RBC transmission properties, a critical scrape-back energy of approximately 32 mJcm(-2) was determined from cylindrical samples of photo-polymerized RBC in which the poorly polymerized material was removed. This value correlates to approximately 22% conversion. The critical scrape-back energy was then used to predict scrape-back lengths obtained from samples polymerized at various energy densities. These results confirm the logarithmic relationship between depth of cure and energy of exposure and the reciprocal relationship between irradiance and time of exposure.

  16. Space-based solar power conversion and delivery systems study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Even at reduced rates of growth, the demand for electric power is expected to more than triple between now and 1995, and to triple again over the period 1995-2020. Without the development of new power sources and advanced transmission technologies, it may not be possible to supply electric energy at prices that are conductive to generalized economic welfare. Solar power is renewable and its conversion and transmission from space may be advantageous. The goal of this study is to assess the economic merit of space-based photovoltaic systems for power generation and a power relay satellite for power transmission. In this study, satellite solar power generation and transmission systems, as represented by current configurations of the Satellite Solar Station (SSPS) and the Power Relay Satellite (PRS), are compared with current and future terrestrial power generation and transmission systems to determine their technical and economic suitability for meeting power demands in the period of 1990 and beyond while meeting ever-increasing environmental and social constraints.

  17. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 2, January 16, 1987--April 15, 1987

    SciTech Connect

    Wilson, R.B. Jr.; Chan, Yee Wai

    1987-05-21

    The goal of this research is to develop catalysts that directly convert methane and light hydrocarbons to intermediates that can, as economics dictate, be subsequently converted either to liquid fuels or value-added chemicals. In this program we are exploring two approaches to developing such catalysts. The first approach consists of developing advanced catalysts for reforming methane. We will prepare the catalysts by reacting organometallic complexes of transition metals (Fe, Ru, Rh, and Re) with zeolitic and rare-earth-exchanged zeolitic supports to produce surfaceconfined metal complexes in the zeolite pores. Our second approach entails synthesizing the porphyrin and phthalocyanine complexes of Cr, Mn, Ru, Fe, and/or Co within the pores of zeolitic supports for use as selective oxidation catalysts for methane and light hydrocarbons. During the second quarter of this project, we concentrated on methane reforming. Two ruthenium clusters (Ru{sub 4} and Ru{sub 6}) supported on three types of support materials ({beta}-alumina, 5 {Angstrom} molecular sieves, and {gamma}-zeolite) were tested for methane reforming. The effects of cluster size, supporting material, and reaction conditions were evaluated. The methane conversions range from 1.74 to 10.11% at 750{degrees}C. The reaction product contains hydrogen, C{sub 2} hydrocarbons, and C{sub 6} or higher hydrocarbons. Up to 48.34% yield of hydrocarbon (C{sub 2}+) is obtained based on reacted methane. Some of these catalysts show very good coking resistance compared with a commercial ruthenium catalyst. Addition of oxygen to these reactions significantly increases the percent methane conversion at lower reaction temperature. However, carbon dioxide and water are the major products in the presence of oxygen.

  18. Optical isolator based on mode conversion in magnetic garnet films.

    PubMed

    Hemme, H; Dötsch, H; Menzler, H P

    1987-09-15

    Calculations are presented describing a novel optical isolator which works by complete TE(0)-TM(0) mode conversion in magnetic garnet films caused by stress-induced optical anisotropy (50%) and by Faraday rotation (50%). These conversions take place along two different, perpendicular light paths in the same crystal that are connected by an integrated mirror. Possible tolerances of the film parameters are given so that a 30-dB isolation is still guaranteed.

  19. Contemporary Status of Studies on Direct Conversion of Solar Energy to Electrical Energy (Sovremennoe Sostoyanie Issledovanii po Pryamomu Preobrazovaniyu Solnechnoi Energii v Elektrocheskuyu),

    DTIC Science & Technology

    Photoelectric, thermoelectric and thermoemission methods of direct conversion of solar energy into electric energy are studied. The article presents a review of modern methods of investigation. (Author)

  20. Bipolar ion detector based on sequential conversion reactions.

    PubMed

    Li, Ming-Hsin; Tsai, Shang-Ting; Chen, Chung-Hsuan; Chen, Chiu Wen; Lee, Yuan Tseh; Wang, Yi-Sheng

    2007-02-15

    This work demonstrates the feasibility of a novel scintillation detector with greater detection efficiency than that of chevron-type microchannel plate (MCP) detectors. The detection mechanism involves sequential conversion reactions induced by ion-surface impacts. Identical detection conditions can be utilized to monitor both positive and negative ions in mass spectrometers. The proposed detector comprises an ion beam guiding device, a negatively biased washer-shaped conversion dynode, and an aluminum-coated scintillation detector. The beam guide changes the electric field around the washer-shaped conversion dynode, and it allows the primary and secondary ions to propagate toward the scintillation phosphor and the conversion dynode, respectively. The detection is achieved by the detection of electron-induced luminescence on a phosphor. The amplification efficiency of this bipolar ion detector increases as the conversion dynode voltage increases. For ions with a mass-to-charge ratio of up to 90 000, the sensitivity of the BID is 1.4-14.4 times that of the MCP. Further improvement of the sensitivity can be achieved by increasing the conversion dynode voltage or the ion acceleration voltage. Results of this study demonstrate that this detector is a promising alternative for efficient ion detection.

  1. Directed plant cell-wall accumulation of iron: Embedding co-catalyst for efficient biomass conversion

    DOE PAGES

    Lin, Chien -Yuan; Jakes, Joseph E.; Donohoe, Bryon S.; ...

    2016-10-21

    Plant lignocellulosic biomass is an abundant, renewable feedstock for the production of biobased fuels and chemicals. Previously, we showed that iron can act as a co-catalyst to improve the deconstruction of lignocellulosic biomass. However, directly adding iron catalysts into biomass prior to pretreatment is diffusion limited, and increases the cost of biorefinery operations. Recently, we developed a new strategy for expressing iron-storage protein ferritin intracellularly to accumulate iron as a catalyst for the downstream deconstruction of lignocellulosic biomass. In this study, we extend this approach by fusing the heterologous ferritin gene with a signal peptide for secretion into Arabidopsis cellmore » walls (referred to here as FerEX). The transgenic Arabidopsis plants. FerEX. accumulated iron under both normal and iron-fertilized growth conditions; under the latter (iron-fertilized) condition, FerEX transgenic plants showed an increase in plant height and dry weight by 12 and 18 %, respectively, compared with the empty vector control plants. The SDS- and native-PAGE separation of cell-wall protein extracts followed by Western blot analyses confirmed the extracellular expression of ferritin in FerEX plants. Meanwhile, Perls' Prussian blue staining and X-ray fluorescence microscopy (XFM) maps revealed iron depositions in both the secondary and compound middle lamellae cell-wall layers, as well as in some of the corner compound middle lamella in FerEX. Remarkably, their harvested biomasses showed enhanced pretreatability and digestibility, releasing, respectively, 21 % more glucose and 34 % more xylose than the empty vector control plants. These values are significantly higher than those of our recently obtained ferritin intracellularly expressed plants. This study demonstrated that extracellular expression of ferritin in Arabidopsis can produce plants with increased growth and iron accumulation, and reduced thermal and enzymatic recalcitrance. Here, the

  2. Directed plant cell-wall accumulation of iron: Embedding co-catalyst for efficient biomass conversion

    SciTech Connect

    Lin, Chien -Yuan; Jakes, Joseph E.; Donohoe, Bryon S.; Ciesielski, Peter N.; Yang, Haibing; Gleber, Sophie -Charlotte; Vogt, Stefan; Ding, Shi -You; Peer, Wendy A.; Murphy, Angus S.; McCann, Maureen C.; Himmel, Michael E.; Tucker, Melvin P.; Wei, Hui

    2016-10-21

    Plant lignocellulosic biomass is an abundant, renewable feedstock for the production of biobased fuels and chemicals. Previously, we showed that iron can act as a co-catalyst to improve the deconstruction of lignocellulosic biomass. However, directly adding iron catalysts into biomass prior to pretreatment is diffusion limited, and increases the cost of biorefinery operations. Recently, we developed a new strategy for expressing iron-storage protein ferritin intracellularly to accumulate iron as a catalyst for the downstream deconstruction of lignocellulosic biomass. In this study, we extend this approach by fusing the heterologous ferritin gene with a signal peptide for secretion into Arabidopsis cell walls (referred to here as FerEX). The transgenic Arabidopsis plants. FerEX. accumulated iron under both normal and iron-fertilized growth conditions; under the latter (iron-fertilized) condition, FerEX transgenic plants showed an increase in plant height and dry weight by 12 and 18 %, respectively, compared with the empty vector control plants. The SDS- and native-PAGE separation of cell-wall protein extracts followed by Western blot analyses confirmed the extracellular expression of ferritin in FerEX plants. Meanwhile, Perls' Prussian blue staining and X-ray fluorescence microscopy (XFM) maps revealed iron depositions in both the secondary and compound middle lamellae cell-wall layers, as well as in some of the corner compound middle lamella in FerEX. Remarkably, their harvested biomasses showed enhanced pretreatability and digestibility, releasing, respectively, 21 % more glucose and 34 % more xylose than the empty vector control plants. These values are significantly higher than those of our recently obtained ferritin intracellularly expressed plants. This study demonstrated that extracellular expression of ferritin in Arabidopsis can produce plants with increased growth and iron accumulation, and reduced thermal and enzymatic recalcitrance. Here, the results are

  3. Radiation-initiated conversion of paraffins to engine fuel: Direct and indirect initiation

    NASA Astrophysics Data System (ADS)

    Metreveli, A. K.; Ponomarev, A. V.

    2016-07-01

    Formation of gasoline and diesel fuel has been investigated using three various radiation-induced ways: (1) cracking of wax, (2) synthesis from methane, (3) high-temperature conversion of wax dilute solution in methane. The wax, synthesized by Fischer-Tropsch method, initially contained a mixture of C17-C120 linear paraffins. The yield of wax conversion to liquid mixture (C4-C27 alkenes and 61.5% alkanes) via mode (1) was 0.83±0.09 μmole/J, whereas yield of gas conversion to liquid mixture (C5-C13 alkanes) via mode (2) was 0.95±0.02 μmole/J. In the dilute solution wax underwent indirect action of radiation. In comparison with (1) the mode (3) produces similar amount of lighter fuel containing 80% of alkanes (C5-C15). At the same time degree of methane fixation is almost three times higher.

  4. Cerium-based conversion coatings on magnesium alloys

    NASA Astrophysics Data System (ADS)

    Castano Londono, Carlos Eduardo

    This research is primarily focused on gaining a better understanding of the deposition and corrosion behavior of cerium-based conversion coatings (CeCCs) on AZ31B and AZ91D Mg alloys. Deposition of homogenous and protective CeCCs was highly dependent on the surface preparation steps. The best results were obtained when Mg samples underwent grinding, acid cleaning, and alkaline cleaning processes. This reduced the number of active cathodic sites and promoted the formation of a protective Al-rich Mg oxide/hydroxide layer. Electrochemical properties of the CeCCs were also strongly correlated with morphological, microstructural, and chemical characteristics. Protective CeCCs were deposited on both AZ31 and AZ91 Mg alloys using a range of deposition times (5 to 180 s) and temperatures (10 to 80 °C). However, shorter deposition times (5 s) and lower deposition temperatures (~10 °C) showed higher impedance and longer bath stability than other deposition conditions. The increase in impedance was related with fewer cracks and smaller nodule sizes. Additional investigations of post-treated CeCCs exposed to NaCl environments showed an increased in the total impedance. The increase in corrosion protection of the CeCCs was associated with an overall increase in coating thickness from 400 to 800 nm. A microstructural evolution from ~3 nm nodular nanocrystals of CeO2/CePO4*H2O embedded in an amorphous matrix to >50 nm CePO4*H2O nanocrystals was responsible for the electrochemically active corrosion protection. Exposure of CeCCs to sunlight in humid environments promoted the reduction of Ce(IV) into Ce(III) species compared to unexposed coatings. This reduction process was related with photocatalytic water oxidation reaction.

  5. Experimental characterization of a direct conversion amorphous selenium detector with thicker conversion layer for dual-energy contrast-enhanced breast imaging.

    PubMed

    Scaduto, David A; Tousignant, Olivier; Zhao, Wei

    2017-08-01

    Dual-energy contrast-enhanced imaging is being investigated as a tool to identify and localize angiogenesis in the breast, a possible indicator of malignant tumors. This imaging technique requires that x-ray images are acquired at energies above the k-shell binding energy of an appropriate radiocontrast agent. Iodinated contrast agents are commonly used for vascular imaging, and require x-ray energies greater than 33 keV. Conventional direct conversion amorphous selenium (a-Se) flat-panel imagers for digital mammography show suboptimal absorption efficiencies at these higher energies. We use spatial-frequency domain image quality metrics to evaluate the performance of a prototype direct conversion flat-panel imager with a thicker a-Se layer, specifically fabricated for dual-energy contrast-enhanced breast imaging. Imaging performance was evaluated in a prototype digital breast tomosynthesis (DBT) system. The spatial resolution, noise characteristics, detective quantum efficiency, and temporal performance of the detector were evaluated for dual-energy imaging for both conventional full-field digital mammography (FFDM) and DBT. The zero-frequency detective quantum efficiency of the prototype detector is improved by approximately 20% over the conventional detector for higher energy beams required for imaging with iodinated contrast agents. The effect of oblique entry of x-rays on spatial resolution does increase with increasing photoconductor thickness, specifically for the most oblique views of a DBT scan. Degradation of spatial resolution due to focal spot motion was also observed. Temporal performance was found to be comparable to conventional mammographic detectors. Increasing the a-Se thickness in direct conversion flat-panel imagers results in better performance for dual-energy contrast-enhanced breast imaging. The reduction in spatial resolution due to oblique entry of x-rays is appreciable in the most extreme clinically relevant cases, but may not profoundly

  6. Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

    PubMed Central

    Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

    2013-01-01

    Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications. PMID:24346481

  7. Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide.

    PubMed

    Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

    2013-12-18

    Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications.

  8. Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

    2013-12-01

    Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications.

  9. High-performance liquid-catalyst fuel cell for direct biomass-into-electricity conversion.

    PubMed

    Liu, Wei; Mu, Wei; Deng, Yulin

    2014-12-01

    Herein, we report high-performance fuel cells that are catalyzed solely by polyoxometalate (POM) solution without any solid metal or metal oxide. The novel design of the liquid-catalyst fuel cells (LCFC) changes the traditional gas-solid-surface heterogeneous reactions to liquid-catalysis reactions. With this design, raw biomasses, such as cellulose, starch, and even grass or wood powders can be directly converted into electricity. The power densities of the fuel cell with switchgrass (dry powder) and bush allamanda (freshly collected) are 44 mW cm(-2) and 51 mW cm(-2) respectively. For the cellulose-based biomass fuel cell, the power density is almost 3000 times higher than that of cellulose-based microbial fuel cells. Unlike noble-metal catalysts, POMs are tolerant to most organic and inorganic contaminants. Therefore, almost any raw biomass can be used directly to produce electricity without prior purification. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A web-based rapid prototyping and clinical conversational system that complements electronic patient record system.

    PubMed

    Kim, J H; Ferziger, R; Kawaloff, H B; Sands, D Z; Safran, C; Slack, W V

    2001-01-01

    Even the most extensive hospital information system cannot support all the complex and ever-changing demands associated with a clinical database, such as providing department or personal data forms, and rating scales. Well-designed clinical dialogue programs may facilitate direct interaction of patients with their medical records. Incorporation of extensive and loosely structured clinical data into an existing medical record system is an essential step towards a comprehensive clinical information system, and can best be achieved when the practitioner and the patient directly enter the contents. We have developed a rapid prototyping and clinical conversational system that complements the electronic medical record system, with its generic data structure and standard communication interfaces based on Web technology. We believe our approach can enhance collaboration between consumer-oriented and provider-oriented information systems.

  11. Compact polarization rotator based on directional coupler of two waveguides with different width and height

    NASA Astrophysics Data System (ADS)

    Liu, Ping; Yang, Junbo; Gao, Shaobo; Liang, Linmei

    2016-10-01

    The polarization control(PC), as one of the important issues in photonic information technologies, has attracted great attention. In this paper, we proposed an efficient and compact polarization converter on silicon-on-insulator (SOI) platform based on asymmetrical direction couplers (ADCs). The ADCs consists of two parallel fully etched straight waveguides with different sizes in both width and height. This polarization converter can realize direct conversion between the TE0 mode and the TM0 mode with high conversion efficiency. Numerical simulations show that the present PC has a good fabrication tolerance for the variation of the waveguide width and height with high polarization conversion efficiency up to 82%.

  12. Single shot x-ray phase contrast imaging using a direct conversion microstrip detector with single photon sensitivity

    SciTech Connect

    Kagias, M.; Cartier, S.; Wang, Z.; Stampanoni, M.; Bergamaschi, A.; Dinapoli, R.; Mozzanica, A.; Schmitt, B.

    2016-06-06

    X-ray phase contrast imaging enables the measurement of the electron density of a sample with high sensitivity compared to the conventional absorption contrast. This is advantageous for the study of dose-sensitive samples, in particular, for biological and medical investigations. Recent developments relaxed the requirement for the beam coherence, such that conventional X-ray sources can be used for phase contrast imaging and thus clinical applications become possible. One of the prominent phase contrast imaging methods, Talbot-Lau grating interferometry, is limited by the manufacturing, alignment, and photon absorption of the analyzer grating, which is placed in the beam path in front of the detector. We propose an alternative improved method based on direct conversion charge integrating detectors, which enables a grating interferometer to be operated without an analyzer grating. Algorithms are introduced, which resolve interference fringes with a periodicity of 4.7 μm recorded with a 25 μm pitch Si microstrip detector (GOTTHARD). The feasibility of the proposed approach is demonstrated by an experiment at the TOMCAT beamline of the Swiss Light Source on a polyethylene sample.

  13. Single shot x-ray phase contrast imaging using a direct conversion microstrip detector with single photon sensitivity

    NASA Astrophysics Data System (ADS)

    Kagias, M.; Cartier, S.; Wang, Z.; Bergamaschi, A.; Dinapoli, R.; Mozzanica, A.; Schmitt, B.; Stampanoni, M.

    2016-06-01

    X-ray phase contrast imaging enables the measurement of the electron density of a sample with high sensitivity compared to the conventional absorption contrast. This is advantageous for the study of dose-sensitive samples, in particular, for biological and medical investigations. Recent developments relaxed the requirement for the beam coherence, such that conventional X-ray sources can be used for phase contrast imaging and thus clinical applications become possible. One of the prominent phase contrast imaging methods, Talbot-Lau grating interferometry, is limited by the manufacturing, alignment, and photon absorption of the analyzer grating, which is placed in the beam path in front of the detector. We propose an alternative improved method based on direct conversion charge integrating detectors, which enables a grating interferometer to be operated without an analyzer grating. Algorithms are introduced, which resolve interference fringes with a periodicity of 4.7 μm recorded with a 25 μm pitch Si microstrip detector (GOTTHARD). The feasibility of the proposed approach is demonstrated by an experiment at the TOMCAT beamline of the Swiss Light Source on a polyethylene sample.

  14. Modeling Single-Event Transient Propagation in a SiGe BiCMOS Direct-Conversion Receiver

    NASA Astrophysics Data System (ADS)

    Ildefonso, Adrian; Song, Ickhyun; Tzintzarov, George N.; Fleetwood, Zachary E.; Lourenco, Nelson E.; Wachter, Mason T.; Cressler, John D.

    2017-08-01

    The propagation of single-event transient (SET) signals in a silicon-germanium direct-conversion receiver carrying modulated data is explored. A theoretical analysis of transient propagation, verified by simulation, is presented. A new methodology to characterize and quantify the impact of SETs in communication systems carrying modulated data is proposed. The proposed methodology uses a pulsed radiation source to induce distortions in the signal constellation. The error vector magnitude due to SETs can then be calculated to quantify errors. Two different modulation schemes were simulated: QPSK and 16-QAM. The distortions in the constellation diagram agree with the presented circuit theory. Furthermore, the proposed methodology was applied to evaluate the improvements in the SET response due to a known radiation-hardening-by-design (RHBD) technique, where the common-base device of the low-noise amplifier was operated in inverse mode. The proposed methodology can be a valid technique to determine the most sensitive parts of a system carrying modulated data.

  15. 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.

  16. Transforming Supervision: Using Video Elicitation to Support Preservice Teacher-Directed Reflective Conversations

    ERIC Educational Resources Information Center

    Sewall, Marcia

    2009-01-01

    Since constraints on time, resources, and even energy often come into play in finding opportunities for meaningful discussions about pedagogy between the novice teacher (NT) and the supervisor, post-lesson conversations at the school site can often be brief, superficial, lacking reflective self-analysis, narrow in focus, interrupted, or even…

  17. Conversational Agents for Academically Productive Talk: A Comparison of Directed and Undirected Agent Interventions

    ERIC Educational Resources Information Center

    Tegos, Stergios; Demetriadis, Stavros; Papadopoulos, Pantelis M.; Weinberger, Armin

    2016-01-01

    Conversational agents that draw on the framework of academically productive talk (APT) have been lately shown to be effective in helping learners sustain productive forms of peer dialogue in diverse learning settings. Yet, literature suggests that more research is required on how learners respond to and benefit from such flexible agents in order…

  18. Conversational Agents for Academically Productive Talk: A Comparison of Directed and Undirected Agent Interventions

    ERIC Educational Resources Information Center

    Tegos, Stergios; Demetriadis, Stavros; Papadopoulos, Pantelis M.; Weinberger, Armin

    2016-01-01

    Conversational agents that draw on the framework of academically productive talk (APT) have been lately shown to be effective in helping learners sustain productive forms of peer dialogue in diverse learning settings. Yet, literature suggests that more research is required on how learners respond to and benefit from such flexible agents in order…

  19. Synthesis and processing of materials for direct thermal-to-electric energy conversion and storage

    NASA Astrophysics Data System (ADS)

    Thompson, Travis

    Currently, fossil fuels are the primary source of energy. Mechanical heat engines convert the chemical potential energy in fossil fuels to useful electrical energy through combustion; a relatively low efficiency process that generates carbon dioxide. This practice has led to a significant increase in carbon dioxide emissions and is contributing to climate change. However, not all heat engines are mechanical. Alternative energy generation technologies to mechanical heat engines are known, yet underutilized. Thermoelectric generators are solid-state devices originally developed by NASA to power deep space spacecraft, which can also convert heat into electricity but without any moving parts. Similar to their mechanical counterparts, any heat source, including the burning of fossil fuels, can be used. However, clean heat sources, such as concentrated solar, can alternatively be used. Since the energy sources for many of the alternative energy technologies is intermittent, including concentrated solar for thermoelectric devices, load matching is difficult or impossible and an energy storage technology is needed in addition to the energy conversion technology. This increases the overall cost and complexity of the systems since two devices are required and represents a significant barrier for mass adoption of an alternative energy technology. However, it is possible to convert heat energy to electrical energy and store excess charge for use at a later time when the demand increases, in a single device. One such of a device is a thermogalvanic generator and is the electrochemical analog of electronic thermoelectric devices. Essentially, a thermogalvanic device represents the combination of thermoelectric and galvanic systems. As such, the rich history of strategies developed by both the thermoelectric community to better the performance of thermoelectric devices and by the electrochemical community to better traditional galvanic devices (i.e. batteries) can be applied to

  20. Improved direct torque control of an induction generator used in a wind conversion system connected to the grid.

    PubMed

    Abdelli, Radia; Rekioua, Djamila; Rekioua, Toufik; Tounzi, Abdelmounaïm

    2013-07-01

    This paper presents a modulated hysteresis direct torque control (MHDTC) applied to an induction generator (IG) used in wind energy conversion systems (WECs) connected to the electrical grid through a back-to-back converter. The principle of this strategy consists in superposing to the torque reference a triangular signal, as in the PWM strategy, with the desired switching frequency. This new modulated reference is compared to the estimated torque by using a hysteresis controller as in the classical direct torque control (DTC). The aim of this new approach is to lead to a constant frequency and low THD in grid current with a unit power factor and a minimum voltage variation despite the wind variation. To highlight the effectiveness of the proposed method, a comparison was made with classical DTC and field oriented control method (FOC). The obtained simulation results, with a variable wind profile, show an adequate dynamic of the conversion system using the proposed method compared to the classical approaches.

  1. Concise review: Generation of neurons from somatic cells of healthy individuals and neurological patients through induced pluripotency or direct conversion.

    PubMed

    Velasco, Iván; Salazar, Patricia; Giorgetti, Alessandra; Ramos-Mejía, Verónica; Castaño, Julio; Romero-Moya, Damià; Menendez, Pablo

    2014-11-01

    Access to healthy or diseased human neural tissue is a daunting task and represents a barrier for advancing our understanding about the cellular, genetic, and molecular mechanisms underlying neurogenesis and neurodegeneration. Reprogramming of somatic cells to pluripotency by transient expression of transcription factors was achieved a few years ago. Induced pluripotent stem cells (iPSC) from both healthy individuals and patients suffering from debilitating, life-threatening neurological diseases have been differentiated into several specific neuronal subtypes. An alternative emerging approach is the direct conversion of somatic cells (i.e., fibroblasts, blood cells, or glial cells) into neuron-like cells. However, to what extent neuronal direct conversion of diseased somatic cells can be achieved remains an open question. Optimization of current expansion and differentiation approaches is highly demanded to increase the differentiation efficiency of specific phenotypes of functional neurons from iPSCs or through somatic cell direct conversion. The realization of the full potential of iPSCs relies on the ability to precisely modify specific genome sequences. Genome editing technologies including zinc finger nucleases, transcription activator-like effector nucleases, and clustered regularly interspaced short palindromic repeat/CAS9 RNA-guided nucleases have progressed very fast over the last years. The combination of genome-editing strategies and patient-specific iPSC biology will offer a unique platform for in vitro generation of diseased and corrected neural derivatives for personalized therapies, disease modeling and drug screening.

  2. Focal spot deblurring for high resolution direct conversion x-ray detectors

    NASA Astrophysics Data System (ADS)

    Setlur Nagesh, S. V.; Rana, R.; Russ, M.; Ionita, Ciprian N.; Bednarek, D. R.; Rudin, S.

    2016-03-01

    Small pixel high resolution direct x-ray detectors have the advantage of higher spatial sampling and decreased blurring characteristic. The limiting factors for such systems becomes the degradation due to the focal spot size. One solution is a smaller focal spot; however, this can limit the output of the x-ray tube. Here a software solution of deconvolving with an estimated focal spot blur is presented. To simulate images from a direct detector affected with focal-spot blur, first a set of high-resolution stent images (FRED from Microvention, Inc., Tustin, CA) were acquired using a 75μm pixel size Dexela-Perkin-Elmer detector and frame averaged to reduce quantum noise. Then the averaged image was blurred with a known Gaussian blur. To add noise to the blurred image a flat-field image was multiplied with the blurred image. Both the ideal and the noisy-blurred images were then deconvolved with the known Gaussian function using either threshold-based inverse filtering or Weiner deconvolution. The blur in the ideal image was removed and the details were recovered successfully. However, the inverse filtering deconvolution process is extremely susceptible to noise. The Weiner deconvolution process was able to recover more of the details of the stent from the noisy-blurred image, but for noisier images, stent details are still lost in the recovery process.

  3. Focal Spot Deblurring for High Resolution Direct Conversion X-ray Detectors.

    PubMed

    Nagesh, S V Setlur; Rana, R; Russ, M; Ionita, Ciprian N; Bednarek, D R; Rudin, S

    2016-02-27

    Small pixel high resolution direct x-ray detectors have the advantage of higher spatial sampling and decreased blurring characteristic. The limiting factors for such systems becomes the degradation due to the focal spot size. One solution is a smaller focal spot; however, this can limit the output of the x-ray tube. Here a software solution of deconvolving with an estimated focal spot blur is presented. To simulate images from a direct detector affected with focal-spot blur, first a set of high-resolution stent images (FRED from Microvention, Inc., Tustin, CA) were acquired using a 75μm pixel size Dexela-Perkin-Elmer detector and frame averaged to reduce quantum noise. Then the averaged image was blurred with a known Gaussian blur. To add noise to the blurred image a flat-field image was multiplied with the blurred image. Both the ideal and the noisy-blurred images were then deconvolved with the known Gaussian function using either threshold-based inverse filtering or Weiner deconvolution. The blur in the ideal image was removed and the details were recovered successfully. However, the inverse filtering deconvolution process is extremely susceptible to noise. The Weiner deconvolution process was able to recover more of the details of the stent from the noisy-blurred image, but for noisier images, stent details are still lost in the recovery process.

  4. Half-time Tc-99m sestamibi imaging with a direct conversion molecular breast imaging system

    PubMed Central

    2014-01-01

    Background In an effort to reduce necessary acquisition time to perform molecular breast imaging (MBI), we compared diagnostic performance of MBI performed with standard 10-min-per-view acquisitions and half-time 5-min-per-view acquisitions, with and without wide beam reconstruction (WBR) processing. Methods Eighty-two bilateral, two-view MBI studies were reviewed. Studies were performed with 300 MBq Tc-99 m sestamibi and a direct conversion molecular breast imaging (DC-MBI) system. Acquisitions were 10 min-per-view; the first half of each was extracted to create 5-min-per-view datasets, and WBR processing was applied. The 10-min-, 5-min-, and 5-min-per-view WBR studies were independently interpreted in a randomized, blinded fashion by two radiologists. Assessments of 1 to 5 were assigned; 4 and 5 were considered test positive. Background parenchymal uptake, lesion type, distribution of non-mass lesions, lesion intensity, and image quality were described. Results Considering detection of all malignant and benign lesions, 5 min-per-view MBI had lower sensitivity (mean of 70% vs. 85% (p ≤ 0.04) for two readers) and lower area under curve (AUC) (mean of 92.7 vs. 99.6, p ≤ 0.01) but had similar specificity (p = 1.0). WBR processing did not alter sensitivity, specificity, or AUC obtained at 5 min-per-view. Overall agreement in final assessment between 5-min-per-view and 10-min-per-view acquisition types was near perfect (κ = 0.82 to 0.89); however, fair to moderate agreement was observed for assessment category 3 (probably benign) (κ = 0.24 to 0.48). Of 33 malignant lesions, 6 (18%) were changed from assessment of 4 or 5 with 10-min-per-view MBI to assessment of 3 with 5-min-per-view MBI. Image quality of 5-min-per-view studies was reduced compared to 10-min-per-view studies for both readers (3.24 vs. 3.98, p < 0.0001 and 3.60 vs. 3.91, p < 0.0001). WBR processing improved image quality for one reader (3.85 vs. 3.24, p < 0

  5. Half-time Tc-99m sestamibi imaging with a direct conversion molecular breast imaging system.

    PubMed

    Hruska, Carrie B; Conners, Amy Lynn; Jones, Katie N; Weinmann, Amanda L; Lingineni, Ravi K; Carter, Rickey E; Rhodes, Deborah J; O'Connor, Michael K

    2014-01-15

    In an effort to reduce necessary acquisition time to perform molecular breast imaging (MBI), we compared diagnostic performance of MBI performed with standard 10-min-per-view acquisitions and half-time 5-min-per-view acquisitions, with and without wide beam reconstruction (WBR) processing. Eighty-two bilateral, two-view MBI studies were reviewed. Studies were performed with 300 MBq Tc-99 m sestamibi and a direct conversion molecular breast imaging (DC-MBI) system. Acquisitions were 10 min-per-view; the first half of each was extracted to create 5-min-per-view datasets, and WBR processing was applied.The 10-min-, 5-min-, and 5-min-per-view WBR studies were independently interpreted in a randomized, blinded fashion by two radiologists. Assessments of 1 to 5 were assigned; 4 and 5 were considered test positive. Background parenchymal uptake, lesion type, distribution of non-mass lesions, lesion intensity, and image quality were described. Considering detection of all malignant and benign lesions, 5 min-per-view MBI had lower sensitivity (mean of 70% vs. 85% (p ≤ 0.04) for two readers) and lower area under curve (AUC) (mean of 92.7 vs. 99.6, p ≤ 0.01) but had similar specificity (p = 1.0). WBR processing did not alter sensitivity, specificity, or AUC obtained at 5 min-per-view.Overall agreement in final assessment between 5-min-per-view and 10-min-per-view acquisition types was near perfect (κ = 0.82 to 0.89); however, fair to moderate agreement was observed for assessment category 3 (probably benign) (κ = 0.24 to 0.48). Of 33 malignant lesions, 6 (18%) were changed from assessment of 4 or 5 with 10-min-per-view MBI to assessment of 3 with 5-min-per-view MBI. Image quality of 5-min-per-view studies was reduced compared to 10-min-per-view studies for both readers (3.24 vs. 3.98, p < 0.0001 and 3.60 vs. 3.91, p < 0.0001). WBR processing improved image quality for one reader (3.85 vs. 3.24, p < 0.0001). Although similar

  6. A MEMS-Based Fuel Cell for Microscale Energy Conversion

    SciTech Connect

    Morse, J; Jankowski, A

    2002-02-01

    A novel approach to realize a miniature fuel cell power source by combining thin film solid-oxide or proton exchange membrane electrolyte-electrode materials with MEMS techniques to integrate a fuel cell stack monolithically on a manifolded host structure is described. This architecture enable a scalable, portable fuel cell power source system for a broad range of applications having power requirements in the < 1 W to > 10 W regime. The MEMS approach offers a direct means to integrate the fuel cell stack with required manifolding and fuel delivery system, while providing the means to control the performance of the power source for specific applications. Results describing the fabrication, integration, and testing of MEMS-based fuel cells are presented below.

  7. Direct conversion of root primordium into shoot meristem relies on timing of stem cell niche development.

    PubMed

    Rosspopoff, Olga; Chelysheva, Liudmila; Saffar, Julie; Lecorgne, Lena; Gey, Delphine; Caillieux, Erwann; Colot, Vincent; Roudier, François; Hilson, Pierre; Berthomé, Richard; Da Costa, Marco; Rech, Philippe

    2017-04-01

    To understand how the identity of an organ can be switched, we studied the transformation of lateral root primordia (LRP) into shoot meristems in Arabidopsis root segments. In this system, the cytokinin-induced conversion does not involve the formation of callus-like structures. Detailed analysis showed that the conversion sequence starts with a mitotic pause and is concomitant with the differential expression of regulators of root and shoot development. The conversion requires the presence of apical stem cells, and only LRP at stages VI or VII can be switched. It is engaged as soon as cell divisions resume because their position and orientation differ in the converting organ compared with the undisturbed emerging LRP. By alternating auxin and cytokinin treatments, we showed that the root and shoot organogenetic programs are remarkably plastic, as the status of the same plant stem cell niche can be reversed repeatedly within a set developmental window. Thus, the networks at play in the meristem of a root can morph in the span of a couple of cell division cycles into those of a shoot, and back, through transdifferentiation.

  8. 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.

  9. Tunable Polarization Conversion and Rotation based on a Reconfigurable Metasurface.

    PubMed

    Zhang, M; Zhang, W; Liu, A Q; Li, F C; Lan, C F

    2017-09-21

    Polarization is an important property of electromagnetic (EM) wave and different polarization manipulations are required for varied optical applications. Here we report a reconfigurable metasurface which achieves both the polarization conversion and the polarization rotation in THz regime. The metasurface is reconfigured through the micro-electro-mechanical-systems (MEMS) actuation. The cross polarization transmittance from a linear polarized incidence is experimentally tuned from 0 to 28% at 2.66 THz. In addition, the polarization rotation angle is effectively changed from -12.8° to 13.1° at 1.78 THz. The tunable bi-functional metasurface for polarization conversion and the polarization rotation can be flexibly applied in various applications such as imaging, polarization microscopy and material analysis, etc.

  10. Direct electrical-to-optical conversion and light modulation in micro whispering-gallery-mode resonators

    NASA Technical Reports Server (NTRS)

    Maleki, Lute (Inventor); Levi, Anthony F. J. (Inventor)

    2005-01-01

    Techniques for directly converting an electrical signal into an optical signal by using a whispering gallery mode optical resonator formed of a dielectric material that allows for direct modulation of optical absorption by the electrical signal.

  11. Adaptive Training for Voice Conversion Based on Eigenvoices

    NASA Astrophysics Data System (ADS)

    Ohtani, Yamato; Toda, Tomoki; Saruwatari, Hiroshi; Shikano, Kiyohiro

    In this paper, we describe a novel model training method for one-to-many eigenvoice conversion (EVC). One-to-many EVC is a technique for converting a specific source speaker's voice into an arbitrary target speaker's voice. An eigenvoice Gaussian mixture model (EV-GMM) is trained in advance using multiple parallel data sets consisting of utterance-pairs of the source speaker and many pre-stored target speakers. The EV-GMM can be adapted to new target speakers using only a few of their arbitrary utterances by estimating a small number of adaptive parameters. In the adaptation process, several parameters of the EV-GMM to be fixed for different target speakers strongly affect the conversion performance of the adapted model. In order to improve the conversion performance in one-to-many EVC, we propose an adaptive training method of the EV-GMM. In the proposed training method, both the fixed parameters and the adaptive parameters are optimized by maximizing a total likelihood function of the EV-GMMs adapted to individual pre-stored target speakers. We conducted objective and subjective evaluations to demonstrate the effectiveness of the proposed training method. The experimental results show that the proposed adaptive training yields significant quality improvements in the converted speech.

  12. Green technology for conversion of renewable hydrocarbon based on plasma-catalytic approach

    NASA Astrophysics Data System (ADS)

    Fedirchyk, Igor; Nedybaliuk, Oleg; Chernyak, Valeriy; Demchina, Valentina

    2016-09-01

    The ability to convert renewable biomass into fuels and chemicals is one of the most important steps on our path to green technology and sustainable development. However, the complex composition of biomass poses a major problem for established conversion technologies. The high temperature of thermochemical biomass conversion often leads to the appearance of undesirable byproducts and waste. The catalytic conversion has reduced yield and feedstock range. Plasma-catalytic reforming technology opens a new path for biomass conversion by replacing feedstock-specific catalysts with free radicals generated in the plasma. We studied the plasma-catalytic conversion of several renewable hydrocarbons using the air plasma created by rotating gliding discharge. We found that plasma-catalytic hydrocarbon conversion can be conducted at significantly lower temperatures (500 K) than during the thermochemical ( 1000 K) and catalytic (800 K) conversion. By using gas chromatography, we determined conversion products and found that conversion efficiency of plasma-catalytic conversion reaches over 85%. We used obtained data to determine the energy yield of hydrogen in case of plasma-catalytic reforming of ethanol and compared it with other plasma-based hydrogen-generating systems.

  13. On-chip optical mode conversion based on dynamic grating in photonic-phononic hybrid waveguide

    PubMed Central

    Chen, Guodong; Zhang, Ruiwen; Sun, Junqiang

    2015-01-01

    We present a scheme for reversible and tunable on-chip optical mode conversion based on dynamic grating in a hybrid photonic-phononic waveguide. The dynamic grating is built up through the acousto-optic effect and the theoretical model of the optical mode conversion is developed by considering the geometrical deformation and refractive index change. Three kinds of mode conversions are able to be realized using the same hybrid waveguide structure in a large bandwidth by only changing the launched acoustic frequency. The complete mode conversion can be achieved by choosing a proper acoustic power under a given waveguide length. PMID:25996236

  14. New colorimetric screening assays for the directed evolution of fungal laccases to improve the conversion of plant biomass

    PubMed Central

    2013-01-01

    Background Fungal laccases are multicopper oxidases with huge applicability in different sectors. Here, we describe the development of a set of high-throughput colorimetric assays for screening laccase libraries in directed evolution studies. Results Firstly, we designed three colorimetric assays based on the oxidation of sinapic acid, acetosyringone and syringaldehyde with λmax of 512, 520 and 370 nm, respectively. These syringyl-type phenolic compounds are released during the degradation of lignocellulose and can act as laccase redox mediators. The oxidation of the three compounds by low and high-redox potential laccases evolved in Saccharomyces cerevisiae produced quantifiable and linear responses, with detection limits around 1 mU/mL and CV values below 16%. The phenolic substrates were also suitable for pre-screening mutant libraries on solid phase format. Intense colored-halos were developed around the yeast colonies secreting laccase. Furthermore, the oxidation of violuric acid to its iminoxyl radical (λmax of 515 nm and CV below 15%) was devised as reporter assay for laccase redox potential during the screening of mutant libraries from high-redox potential laccases. Finally, we developed three dye-decolorizing assays based on the enzymatic oxidation of Methyl Orange (470 nm), Evans Blue (605 nm) and Remazol Brilliant Blue (640 nm) giving up to 40% decolorization yields and CV values below 18%. The assays were reliable for direct measurement of laccase activity or to indirectly explore the oxidation of mediators that do not render colored products (but promote dye decolorization). Every single assay reported in this work was tested by exploring mutant libraries created by error prone PCR of fungal laccases secreted by yeast. Conclusions The high-throughput screening methods reported in this work could be useful for engineering laccases for different purposes. The assays based on the oxidation of syringyl-compounds might be valuable tools for

  15. Conversation Thread Extraction and Topic Detection in Text-Based Chat

    DTIC Science & Technology

    2008-09-01

    Juilliard School , where music and the performing arts are taught, will get $250,000. The Hearst Foundation, a leading supporter of the Lincoln Center ...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited CONVERSATION THREAD...Conversation Thread Extraction and Topic Detection in Text-based Chat Paige Holland Adams Naval Postgraduate School Department of the Navy Approved for

  16. 5 CFR 315.712 - Conversion based on service as a Federal Career Intern.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Career Intern. 315.712 Section 315.712 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS CAREER AND CAREER-CONDITIONAL EMPLOYMENT Conversion to Career or Career-Conditional Employment From Other Types of Employment § 315.712 Conversion based on service as a Federal Career...

  17. 5 CFR 315.712 - Conversion based on service as a Federal Career Intern.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Career Intern. 315.712 Section 315.712 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS CAREER AND CAREER-CONDITIONAL EMPLOYMENT Conversion to Career or Career-Conditional Employment From Other Types of Employment § 315.712 Conversion based on service as a Federal Career...

  18. 5 CFR 315.712 - Conversion based on service as a Federal Career Intern.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Career Intern. 315.712 Section 315.712 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS CAREER AND CAREER-CONDITIONAL EMPLOYMENT Conversion to Career or Career-Conditional Employment From Other Types of Employment § 315.712 Conversion based on service as a Federal Career Intern...

  19. Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

    SciTech Connect

    Narayan, Jagdish Bhaumik, Anagh

    2015-10-01

    We report on fundamental discovery of conversion of amorphous carbon into diamond by irradiating amorphous carbon films with nanosecond lasers at room-temperature in air at atmospheric pressure. We can create diamond in the form of nanodiamond (size range <100 nm) and microdiamond (>100 nm). Nanosecond laser pulses are used to melt amorphous diamondlike carbon and create a highly undercooled state, from which various forms of diamond can be formed upon cooling. The quenching from the super undercooled state results in nucleation of nanodiamond. It is found that microdiamonds grow out of highly undercooled state of carbon, with nanodiamond acting as seed crystals.

  20. A preliminary study on improving the recognition of esophageal speech using a hybrid system based on statistical voice conversion.

    PubMed

    Lachhab, Othman; Di Martino, Joseph; Elhaj, Elhassane Ibn; Hammouch, Ahmed

    2015-01-01

    In this paper, we propose a hybrid system based on a modified statistical GMM voice conversion algorithm for improving the recognition of esophageal speech. This hybrid system aims to compensate for the distorted information present in the esophageal acoustic features by using a voice conversion method. The esophageal speech is converted into a "target" laryngeal speech using an iterative statistical estimation of a transformation function. We did not apply a speech synthesizer for reconstructing the converted speech signal, given that the converted Mel cepstral vectors are used directly as input of our speech recognition system. Furthermore the feature vectors are linearly transformed by the HLDA (heteroscedastic linear discriminant analysis) method to reduce their size in a smaller space having good discriminative properties. The experimental results demonstrate that our proposed system provides an improvement of the phone recognition accuracy with an absolute increase of 3.40 % when compared with the phone recognition accuracy obtained with neither HLDA nor voice conversion.

  1. Space-based solar power conversion and delivery systems study. Volume 4: Energy conversion systems studies

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Solar cells and optical configurations for the SSPS were examined. In this task, three specific solar cell materials were examined: single crystal silicon, single crystal gallium arsenide, and polycrystalline cadmium sulfide. The comparison of the three different cells on the basis of a subsystem parametric cost per kW of SSPS-generated power at the terrestrial utility interface showed that gallium arsenide was the most promising solar cell material at high concentration ratios. The most promising solar cell material with no concentration, was dependent upon the particular combination of parameters representing cost, mass and performance that were chosen to represent each cell in this deterministic comparative analysis. The potential for mass production, based on the projections of the present state-of-the-art would tend to favor cadmium sulfide in lieu of single crystal silicon or gallium arsenide solar cells.

  2. Innovative Energy conversion Schemes for Space Based Strategic Defense Systems

    DTIC Science & Technology

    1988-01-01

    theoretical for matter/ antimatter conversion to pure energy is c2 « 9 x 1013 kj 3.5X1011 7.0xl010 3.5xl010 1.5xl09 5.0xl08 2.5xl06 1.8xl06 1.2xl05...range, depending on operating temperature, but require heat engines with moving parts to extract electrical power. Figure 3 shows an early NASA...dedicated systems engineering and application of existing microwave technology. For a given orbital scenario, the key parameter influencing microwave

  3. Archetype-based conversion of EHR content models: pilot experience with a regional EHR system

    PubMed Central

    2009-01-01

    Background Exchange of Electronic Health Record (EHR) data between systems from different suppliers is a major challenge. EHR communication based on archetype methodology has been developed by openEHR and CEN/ISO. The experience of using archetypes in deployed EHR systems is quite limited today. Currently deployed EHR systems with large user bases have their own proprietary way of representing clinical content using various models. This study was designed to investigate the feasibility of representing EHR content models from a regional EHR system as openEHR archetypes and inversely to convert archetypes to the proprietary format. Methods The openEHR EHR Reference Model (RM) and Archetype Model (AM) specifications were used. The template model of the Cambio COSMIC, a regional EHR product from Sweden, was analyzed and compared to the openEHR RM and AM. This study was focused on the convertibility of the EHR semantic models. A semantic mapping between the openEHR RM/AM and the COSMIC template model was produced and used as the basis for developing prototype software that performs automated bi-directional conversion between openEHR archetypes and COSMIC templates. Results Automated bi-directional conversion between openEHR archetype format and COSMIC template format has been achieved. Several archetypes from the openEHR Clinical Knowledge Repository have been imported into COSMIC, preserving most of the structural and terminology related constraints. COSMIC templates from a large regional installation were successfully converted into the openEHR archetype format. The conversion from the COSMIC templates into archetype format preserves nearly all structural and semantic definitions of the original content models. A strategy of gradually adding archetype support to legacy EHR systems was formulated in order to allow sharing of clinical content models defined using different formats. Conclusion The openEHR RM and AM are expressive enough to represent the existing clinical

  4. Direct in Situ Conversion of Metals into Metal-Organic Frameworks: A Strategy for the Rapid Growth of MOF Films on Metal Substrates.

    PubMed

    Ji, Hoon; Hwang, Sunhyun; Kim, Keonmok; Kim, CheolGi; Jeong, Nak Cheon

    2016-11-30

    The fabrication of metal-organic framework (MOF) films on conducting substrates has demonstrated great potential in applications such as electronic conduction and sensing. For these applications, direct contact of the film to the conducting substrate without a self-assembled monolayer (SAM) is a desired step that must be achieved prior to the use of MOF films. In this report, we propose an in situ strategy for the rapid one-step conversion of Cu metal into HKUST-1 films on conducting Cu substrates. The Cu substrate acts both as a conducting substrate and a source of Cu(2+) ions during the synthesis of HKUST-1. This synthesis is possible because of the simultaneous reaction of an oxidizing agent and a deprotonating agent, in which the former agent dissolves the metal substrate to form Cu(2+) ions while the latter agent deprotonates the ligand. Using this strategy, the HKUST-1 film could not only be rapidly synthesized within 5 min but also be directly attached to the Cu substrate. Based on microscopic studies, we propose a plausible mechanism for the growth reaction. Furthermore, we show the versatility of this in situ conversion methodology, applying it to ZIF-8, which comprises Zn(2+) ions and imidazole-based ligands. Using an I2-filled HKUST-1 film, we further demonstrate that the direct contact of the MOF film to the conducting substrate makes the material more suitable for use as a sensor or electronic conductor.

  5. 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

  6. Engineering Saccharomyces cerevisiae for direct conversion of raw, uncooked or granular starch to ethanol.

    PubMed

    Görgens, Johann F; Bressler, David C; van Rensburg, Eugéne

    2015-01-01

    The production of raw starch-degrading amylases by recombinant Saccharomyces cerevisiae provides opportunities for the direct hydrolysis and fermentation of raw starch to ethanol without cooking or exogenous enzyme addition. Such a consolidated bioprocess (CBP) for raw starch fermentation will substantially reduce costs associated with energy usage and commercial granular starch hydrolyzing (GSH) enzymes. The core purpose of this review is to provide comprehensive insight into the physiological impact of recombinant amylase production on the ethanol-producing yeast. Key production parameters, based on outcomes from modifications to the yeast genome and levels of amylase production, were compared to key benchmark data. In turn, these outcomes are of significance from a process point of view to highlight shortcomings in the current state of the art of raw starch fermentation yeast compared to a set of industrial standards. Therefore, this study provides an integrated critical assessment of physiology, genetics and process aspects of recombinant raw starch fermenting yeast in relation to presently used technology. Various approaches to strain development were compared on a common basis of quantitative performance measures, including the extent of hydrolysis, fermentation-hydrolysis yield and productivity. Key findings showed that levels of α-amylase required for raw starch hydrolysis far exceeded enzyme levels for soluble starch hydrolysis, pointing to a pre-requisite for excess α-amylase compared to glucoamylase for efficient raw starch hydrolysis. However, the physiological limitations of amylase production by yeast, requiring high biomass concentrations and long cultivation periods for sufficient enzyme accumulation under anaerobic conditions, remained a substantial challenge. Accordingly, the fermentation performance of the recombinant S. cerevisiae strains reviewed in this study could not match the performance of conventional starch fermentation processes

  7. Synthesis of active carbon-based catalysts by chemical vapor infiltration for nitrogen oxide conversion.

    PubMed

    Busch, Martin; Bergmann, Ulf; Sager, Uta; Schmidt, Wolfgang; Schmidt, Frank; Notthoff, Christian; Atakan, Burak; Winterer, Markus

    2011-09-01

    Direct reduction of nitrogen oxides is still a challenge. Strong efforts have been made in developing noble and transition metal catalysts on microporous support materials such as active carbons or zeolites. However, the required activation energy and low conversion rates still limit its breakthrough. Furthermore, infiltration of such microporous matrix materials is commonly performed by wet chemistry routes. Deep infiltration and homogeneous precursor distribution are often challenging due to precursor viscosity or electrostatic shielding and may be inhibited by pore clogging. Gas phase infiltration, as an alternative, can resolve viscosity issues and may contribute to homogeneous infiltration of precursors. In the present work new catalysts based on active carbon substrates were synthesized via chemical vapor infiltration. Iron oxide nano clusters were deposited in the microporous matrix material. Detailed investigation of produced catalysts included nitrogen oxide adsorption, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Catalytic activity was studied in a recycle flow reactor by time-resolved mass spectrometry at a temperature of 423 K. The infiltrated active carbons showed very homogeneous deposition of iron oxide nano clusters in the range of below 12 to 19 nm, depending on the amount of infiltrated precursor. The specific surface area was not excessively reduced, nor was the pore size distribution changed compared to the original substrate. Catalytic nitrogen oxides conversion was detected at temperatures as low as 423 K.

  8. The direct conversion of sugars into 2,5-furandicarboxylic acid in a triphasic system.

    PubMed

    Yi, Guangshun; Teong, Siew Ping; Zhang, Yugen

    2015-04-13

    A one-pot conversion of sugars into 2,5-furandicarboxylic acid (FDCA) is demonstrated in a triphasic system: tetraethylammonium bromide (TEAB) or water-methyl isobutyl ketone (MIBK)-water. In this reaction, sugars are first converted into 5-hydroxymethylfurfural (HMF) in TEAB or water (Phase I). The HMF in Phase I is then extracted to MIBK (Phase II) and transferred to water (Phase III), where HMF is converted into FDCA. Phase II plays multiple roles: as a bridge for HMF extraction, transportation and purification. Overall FDCA yields of 78 % and 50 % are achieved from fructose and glucose respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Direct methane conversion to methanol. Annual report, October 1993--September 1994

    SciTech Connect

    Noble, R.D.; Falconer, J.L.

    1995-01-01

    We proposed to demonstrate the effectiveness of a catalytic membrane reactor (a ceramic membrane combined with a catalyst) to selectively produce methanol by partial oxidation of methane. Methanol is used as a chemical feedstock, gasoline additive, and turbine fuel. Methane partial oxidation using a catalytic membrane reactor has been determined as one of the promising approaches for methanol synthesis from methane. In the original proposal, the membrane was used to selectively remove methanol from the reaction zone before carbon oxides form, thus increasing the methanol yield. Methanol synthesis and separation in one step would also make methane more valuable for producing chemicals and fuels. However, all the membranes tested in this laboratory lost their selectivity under the reaction conditions. A modified non-isothermal, non-permselective membrane reactor then was built and satisfactory results were obtained. The conversion and selectivity data obtained in this laboratory were better than that of the most published studies.

  10. Potentiality of Yeasts in the Direct Conversion of Starchy Materials to Ethanol and Its Relevance in the New Millennium

    NASA Astrophysics Data System (ADS)

    Reddy, L. V. A.; Reddy, O. V. S.; Basappa, S. C.

    In recent years, the use of renewable and abundantly available starchy and cellulosic materials for industrial production of ethanol is gaining importance, in view of the fact, that ethanol is one of the most prospective future motor fuels, that can be expected to replace fossil fuels, which are fast depleting in the world scenario. Although, the starch and the starchy substrates could be converted successfully to ethanol on industrial scales by the use of commercial amylolytic enzymes and yeast fermentation, the cost of production is rather very high. This is mainly due to the non-enzymatic and enzymatic conversion (gelatinization, liquefaction and saccharification) of starch to sugars, which costs around 20 % of the cost of production of ethanol from starch. In this context, the use of amylolytic yeasts, that can directly convert starch to ethanol by a single step, are potentially suited to reduce the cost of production of ethanol from starch. Research advances made in this direction have shown encouraging results, both in terms of identifying the potentially suited yeasts for the purpose and also their economic ethanol yields. This chapter focuses on the types of starch and starchy substrates and their digestion to fermentable sugars, optimization of fermentation conditions to ethanol from starch, factors that affect starch fermentation, potential amylolytic yeasts which can directly convert starch to ethanol, genetic improvement of these yeasts for better conversion efficiency and their future economic prospects in the new millennium.

  11. Stimulation by D-glucose of the direct conversion of arginine to citrulline in enterocytes isolated from pig jejunum

    SciTech Connect

    Blachier, F.; M'Rabet-Touil, H.; Darcy-Vrillon, B.; Posho, L.; Duee, P.H. )

    1991-06-28

    In enterocytes isolated from pig jejunum, L-arginine is metabolized to L-citrulline either directly or indirectly through the sequence of reactions catalysed by arginase and ornithine transcarbamylase. In the presence of 5 mM D-glucose, the direct conversion of 1mM L-(guanido-14C) arginine to L-citrulline was increased more than 4 times. Isolated enterocytes exhibit a high glycolytic capacity. Furthermore, the decarboxylation of 5mM D-(1-14C) glucose was 3.6 fold higher than the decarboxylation of 5 mM D-(6-14C) glucose which suggests the presence of a pentose phosphate pathway in enterocytes. Since the production of labelled L-citrulline from L-(guanido-14C) arginine in pig enterocyte homogenates was markedly increased in the presence of NADPH, it is proposed that the direct conversion of L-arginine to L-citrulline could be stimulated by the production of NADPH from D-glucose in the pentose phosphate pathway.

  12. Direct conversion of light hydrocarbon gases to liquid fuel. Quarterly technical status report No. 11 for thrid quarter FY 1990

    SciTech Connect

    Foral, M.J.

    1990-12-31

    The objective of this program is to investigate the direct conversion of light gaseous hydrocarbons, such as those produced during Fischer-Tropsch synthesis or as a product of gasification, to liquid transportation fuels via a partial oxidation process. The process will be tested in an existing pilot plant to obtain credible mass balances. Specific objectives to be met include determination of optimal process conditions, investigation of various processing options (e.g. feed injection, product quench, and recycle systems), and evaluation of the various options will be performed as experimental data become available.

  13. Recovery Act. Demonstration of a Pilot Integrated Biorefinery for the Efficient, Direct Conversion of Biomass to Diesel Fuel

    SciTech Connect

    Schuetzle, Dennis; Tamblyn, Greg; Caldwell, Matt; Hanbury, Orion; Schuetzle, Robert; Rodriguez, Ramer; Johnson, Alex; Deichert, Fred; Jorgensen, Roger; Struble, Doug

    2015-05-12

    The Renewable Energy Institute International, in collaboration with Greyrock Energy and Red Lion Bio-Energy (RLB) has successfully demonstrated operation of a 25 ton per day (tpd) nameplate capacity, pilot, pre-commercial-scale integrated biorefinery (IBR) plant for the direct production of premium, “drop-in”, synthetic fuels from agriculture and forest waste feedstocks using next-generation thermochemical and catalytic conversion technologies. The IBR plant was built and tested at the Energy Center, which is located in the University of Toledo Medical Campus in Toledo, Ohio.

  14. Direct conversion of light hydrocarbon gases to liquid fuel. Quarterly technical status report No. 23 for second quarter FY 1991

    SciTech Connect

    Foral, M.J.

    1991-12-31

    The objective of this program is to investigate the direct conversion of light gaseous hydrocarbons, such as those produced during Fischer-Tropsch synthesis or as a product of gasification, to liquid transportation fuels via a partial oxidation process. The process will be tested in an existing pilot plant to obtain credible mass balances. Specific objectives to be met include determination of optimal process conditions, investigation of various processing options (e.g. feed injection, product quench, and recycle systems), and evaluation of an enhanced yield thermal/catalytic system. Economic evaluation of the various options will be performed as experimental data become available.

  15. Design of generic coal conversion facilities: Process release---Direct coal liquefaction

    SciTech Connect

    Not Available

    1991-09-01

    The direct liquefaction portion of the PETC generic direct coal liquefaction process development unit (PDU) is being designed to provide maximum operating flexibility. The PDU design will permit catalytic and non-catalytic liquefaction concepts to be investigated at their proof-of-the-concept stages before any larger scale operations are attempted. The principal variations from concept to concept are reactor configurations and types. These include thermal reactor, ebullating bed reactor, slurry phase reactor and fixed bed reactor, as well as different types of catalyst. All of these operating modes are necessary to define and identify the optimum process conditions and configurations for determining improved economical liquefaction technology.

  16. Note: Direct sensor resistance-to-frequency conversion with generalized impedance converter.

    PubMed

    Ramírez Muñoz, D; Sánchez Moreno, J; Casans Berga, S; Navarro Antón, A E

    2010-12-01

    In this note a squared output signal is generated from an astable circuit. Its frequency has a linear dependence on the resistance value of a resistive temperature sensor. The main circuit to obtain this direct relationship is the generalized impedance converter configured as a capacitor controlled by a sensor resistance. The proposed measurement method allows a direct analog-to-digital interface of information involved in resistive sensors. The converter finds applications in portable low voltage and low power design of instrumentation electronic systems.

  17. Power conversion and quality of the Santa Clara 2 MW direct carbonate fuel cell demonstration plant

    SciTech Connect

    Skok, A.J.; Abueg, R.Z.; Schwartz, P.

    1996-12-31

    The Santa Clara Demonstration Project (SCDP) is the first application of a commercial-scale carbonate fuel cell power plant on a US electric utility system. It is also the largest fuel cell power plant ever operated in the United States. The 2MW plant, located in Santa Clara, California, utilizes carbonate fuel cell technology developed by Energy Research Corporation (ERC) of Danbury, Connecticut. The ultimate goal of a fuel cell power plant is to deliver usable power into an electrical distribution system. The power conversion sub-system does this for the Santa Clara Demonstration Plant. A description of this sub-system and its capabilities follows. The sub-system has demonstrated the capability to deliver real power, reactive power and to absorb reactive power on a utility grid. The sub-system can be operated in the same manner as a conventional rotating generator except with enhanced capabilities for reactive power. Measurements demonstrated the power quality from the plant in various operating modes was high quality utility grade power.

  18. A novel PWM control for a bi-directional full-bridge DC-DC converter with smooth conversion mode transitions

    NASA Astrophysics Data System (ADS)

    Lorentz, V. R. H.; Schwarzmann, H.; März, M.; Bauer, A. J.; Ryssel, H.; Frey, L.; Poure, P.; Braun, F.

    2011-08-01

    A novel CMOS integrated pulse-width modulation (PWM) control circuit allowing smooth transitions between conversion modes in full-bridge based bi-directional DC-DC converters operating at high switching frequencies is presented. The novel PWM control circuit is able to drive full-bridge based DC-DC converters performing step-down (i.e. buck) and step-up (i.e. boost) voltage conversion in both directions, thus allowing charging and discharging of the batteries in mobile systems. It provides smooth transitions between buck, buck-boost and boost modes. Additionally, the novel PWM control loop circuit uses a symmetrical triangular carrier, which overcomes the necessity of using an output phasing circuit previously required in PWM controllers based on sawtooth oscillators. The novel PWM control also enables to build bi-directional DC-DC converters operating at high switching frequencies (i.e. up to 10 MHz and above). Finally, the proposed PWM control circuit also allows the use of an average lossless inductor-current sensor for sensing the average load current even at very high switching frequencies. In this article, the proposed PWM control circuit is modelled and the integrated CMOS schematic is given. The corresponding theory is analysed and presented in detail. The circuit simulations realised in the Cadence Spectre software with a commercially available 0.18 µm mixed-signal CMOS technology from UMC are shown. The PWM control circuit was implemented in a monolithic integrated bi-directional CMOS DC-DC converter ASIC prototype. The fabricated prototype was tested experimentally and has shown performances in accordance with the theory.

  19. Directed plant cell-wall accumulation of iron: embedding co-catalyst for efficient biomass conversion

    Treesearch

    Chien-Yuan Lin; Joseph E. Jakes; Bryon S. Donohoe; Peter N. Ciesielski; Haibing Yang; Sophie-Charlotte Gleber; Stefan Vogt; Shi-You Ding; Wendy A. Peer; Angus S. Murphy; Maureen C. McCann; Michael E. Himmel; Melvin P. Tucker; Hui Wei

    2016-01-01

    Background: Plant lignocellulosic biomass is an abundant, renewable feedstock for the production of biobased fuels and chemicals. Previously, we showed that iron can act as a co-catalyst to improve the deconstruction of lignocellulosic biomass. However, directly adding iron catalysts into biomass prior to pretreatment is diffusion limited,...

  20. A 1.2-V CMOS front-end for LTE direct conversion SAW-less receiver

    NASA Astrophysics Data System (ADS)

    Riyan, Wang; Jiwei, Huang; Zhengping, Li; Weifeng, Zhang; Longyue, Zeng

    2012-03-01

    A CMOS RF front-end for the long-term evolution (LTE) direct conversion receiver is presented. With a low noise transconductance amplifier (LNA), current commutating passive mixer and transimpedance operational amplifier (TIA), the RF front-end structure enables high-integration, high linearity and simple frequency planning for LTE multi-band applications. Large variable gain is achieved using current-steering transconductance stages. A current commutating passive mixer with 25% duty-cycle LO improves gain, noise and linearity. A direct coupled current-input filter (DCF) is employed to suppress the out-of-band interferer. Fabricated in a 0.13-μm CMOS process, the RF front-end achieves a 45 dB conversion voltage gain, 2.7 dB NF, -7 dBm IIP3, and +60 dBm IIP2 with calibration from 2.3 to 2.7 GHz. The total RF front end with divider draws 40 mA from a single 1.2-V supply.

  1. Modeling the phenotype of spinal muscular atrophy by the direct conversion of human fibroblasts to motor neurons.

    PubMed

    Zhang, Qi-Jie; Li, Jin-Jing; Lin, Xiang; Lu, Ying-Qian; Guo, Xin-Xin; Dong, En-Lin; Zhao, Miao; He, Jin; Wang, Ning; Chen, Wan-Jin

    2017-02-14

    Spinal muscular atrophy (SMA) is a lethal autosomal recessive neurological disease characterized by selective degeneration of motor neurons in the spinal cord. In recent years, the development of cellular reprogramming technology has provided an alternative and effective method for obtaining patient-specific neurons in vitro. In the present study, we applied this technology to the field of SMA to acquire patient-specific induced motor neurons that were directly converted from fibroblasts via the forced expression of 8 defined transcription factors. The infected fibroblasts began to grow in a dipolar manner, and the nuclei gradually enlarged. Typical Tuj1-positive neurons were generated at day 23. After day 35, induced neurons with multiple neurites were observed, and these neurons also expressed the hallmarks of Tuj1, HB9, ISL1 and CHAT. The conversion efficiencies were approximately 5.8% and 5.5% in the SMA and control groups, respectively. Additionally, the SMA-induced neurons exhibited a significantly reduced neurite outgrowth rate compared with the control neurons. After day 60, the SMA-induced neurons also exhibited a liability of neuronal degeneration and remarkable fracturing of the neurites was observed. By directly reprogramming fibroblasts, we established a feeder-free conversion system to acquire SMA patient-specific induced motor neurons that partially modeled the phenotype of SMA in vitro.

  2. Direct calibration in megavoltage photon beams using Monte Carlo conversion factor: validation and clinical implications.

    PubMed

    Wright, Tracy; Lye, Jessica E; Ramanathan, Ganesan; Harty, Peter D; Oliver, Chris; Webb, David V; Butler, Duncan J

    2015-01-21

    The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has established a method for ionisation chamber calibrations using megavoltage photon reference beams. The new method will reduce the calibration uncertainty compared to a (60)Co calibration combined with the TRS-398 energy correction factor. The calibration method employs a graphite calorimeter and a Monte Carlo (MC) conversion factor to convert the absolute dose to graphite to absorbed dose to water. EGSnrc is used to model the linac head and doses in the calorimeter and water phantom. The linac model is validated by comparing measured and modelled PDDs and profiles. The relative standard uncertainties in the calibration factors at the ARPANSA beam qualities were found to be 0.47% at 6 MV, 0.51% at 10 MV and 0.46% for the 18 MV beam. A comparison with the Bureau International des Poids et Mesures (BIPM) as part of the key comparison BIPM.RI(I)-K6 gave results of 0.9965(55), 0.9924(60) and 0.9932(59) for the 6, 10 and 18 MV beams, respectively, with all beams within 1σ of the participant average. The measured kQ values for an NE2571 Farmer chamber were found to be lower than those in TRS-398 but are consistent with published measured and modelled values. Users can expect a shift in the calibration factor at user energies of an NE2571 chamber between 0.4-1.1% across the range of calibration energies compared to the current calibration method.

  3. Advances in graphene-based semiconductor photocatalysts for solar energy conversion: fundamentals and materials engineering.

    PubMed

    Xie, Xiuqiang; Kretschmer, Katja; Wang, Guoxiu

    2015-08-28

    Graphene-based semiconductor photocatalysis has been regarded as a promising technology for solar energy storage and conversion. In this review, we summarized recent developments of graphene-based photocatalysts, including preparation of graphene-based photocatalysts, typical key advances in the understanding of graphene functions for photocatalytic activity enhancement and methodologies to regulate the electron transfer efficiency in graphene-based composite photocatalysts, by which we hope to offer enriched information to harvest the utmost fascinating properties of graphene as a platform to construct efficient graphene-based composite photocatalysts for solar-to-energy conversion.

  4. Direct conversion of human fibroblasts into functional osteoblasts by defined factors.

    PubMed

    Yamamoto, Kenta; Kishida, Tsunao; Sato, Yoshiki; Nishioka, Keisuke; Ejima, Akika; Fujiwara, Hiroyoshi; Kubo, Toshikazu; Yamamoto, Toshiro; Kanamura, Narisato; Mazda, Osam

    2015-05-12

    Osteoblasts produce calcified bone matrix and contribute to bone formation and remodeling. In this study, we established a procedure to directly convert human fibroblasts into osteoblasts by transducing some defined factors and culturing in osteogenic medium. Osteoblast-specific transcription factors, Runt-related transcription factor 2 (Runx2), and Osterix, in combination with Octamer-binding transcription factor 3/4 (Oct4) and L-Myc (RXOL) transduction, converted ∼ 80% of the fibroblasts into osteocalcin-producing cells. The directly converted osteoblasts (dOBs) induced by RXOL displayed a similar gene expression profile as normal human osteoblasts and contributed to bone repair after transplantation into immunodeficient mice at artificial bone defect lesions. The dOBs expressed endogenous Runx2 and Osterix, and did not require continuous expression of the exogenous genes to maintain their phenotype. Another combination, Oct4 plus L-Myc (OL), also induced fibroblasts to produce bone matrix, but the OL-transduced cells did not express Osterix and exhibited a more distant gene expression profile to osteoblasts compared with RXOL-transduced cells. These findings strongly suggest successful direct reprogramming of fibroblasts into functional osteoblasts by RXOL, a technology that may provide bone regeneration therapy against bone disorders.

  5. Performance of new GPU-based scan-conversion algorithm implemented using OpenGL.

    PubMed

    Steelman, William A; Richard, William D

    2011-04-01

    A new GPU-based scan-conversion algorithm implemented using OpenGL is described. The compute performance of this new algorithm running on a modem GPU is compared to the performance of three common scan-conversion algorithms (nearest-neighbor, linear interpolation and bilinear interpolation) implemented in software using a modem CPU. The quality of the images produced by the algorithm, as measured by signal-to-noise power, is also compared to the quality of the images produced using these three common scan-conversion algorithms.

  6. User alternatives in post-processing for raster-to-vector conversion. [Landsat-based forest mapping

    NASA Technical Reports Server (NTRS)

    Logan, T. L.; Woodcock, C. E.

    1983-01-01

    A number of Landsat-based coniferous forest stratum maps have been created of the Eldorado National Forest in California. These maps were produced in raster image format which is not directly usable by the U.S. Forest Service's vector-based Wildland Resource Information System (WRIS). As a solution, raster-to-vector conversion software has been developed for processing classified images into polygonal data structures. Before conversion, however, the digital classification images must be simplified to remove high spatial variance ('noise', 'speckle') and meet a USFS ten acre minimum requirement. A post-processing (simplification) strategy different from those commonly used in raster image processing may be desired for preparing maps for conversion to vector format, because simplification routines typically permit diagonal connections in the process of reclassifying pixels and forming new polygons. Diagonal connections are often undesirable when converting to vector format because they permit polygons to effectively cross over each other and occupy a common location. Three alternative methodologies are discussed for simplifying raster data for conversion to vector format.

  7. User alternatives in post-processing for raster-to-vector conversion. [Landsat-based forest mapping

    NASA Technical Reports Server (NTRS)

    Logan, T. L.; Woodcock, C. E.

    1983-01-01

    A number of Landsat-based coniferous forest stratum maps have been created of the Eldorado National Forest in California. These maps were produced in raster image format which is not directly usable by the U.S. Forest Service's vector-based Wildland Resource Information System (WRIS). As a solution, raster-to-vector conversion software has been developed for processing classified images into polygonal data structures. Before conversion, however, the digital classification images must be simplified to remove high spatial variance ('noise', 'speckle') and meet a USFS ten acre minimum requirement. A post-processing (simplification) strategy different from those commonly used in raster image processing may be desired for preparing maps for conversion to vector format, because simplification routines typically permit diagonal connections in the process of reclassifying pixels and forming new polygons. Diagonal connections are often undesirable when converting to vector format because they permit polygons to effectively cross over each other and occupy a common location. Three alternative methodologies are discussed for simplifying raster data for conversion to vector format.

  8. Energy conversion of the flare due to direct electric fields from the sheared reconnection

    NASA Astrophysics Data System (ADS)

    Hirayama, T.

    In this paper we present a new mechanism of the main energy conversion of the solar flare. Since a flare inducing prominence (flux tube) rises Vz ⩽ 300 km s-1, the plasmas below it cannot continuously eject with Alfvén speeds of VA = 3000 km s-1 but probably with Vz ≈ ±100 km s-1. Plasma up and downflows with VA will within a short duration be blocked between the chromosphere where reconnected flux tubes are piling up, and the slowly rising flux rope. Hence the Petschek slow shock mechanism is difficult to be realized as a major energy converting mechanism. Adopting a conventional reconnecting morphology, we assume a magnetic component parallel to the photospheric neutral line, i.e. sheared fields of By ≠ 0. Then Gauss’s law leads to non-vanishing electric charges σ; 4πσ = -div(V × B/c) ≈ By∂Vz/c∂x where the horizontal inflow velocity Vx changes to vertical down-flow Vz (e.g. By ≈ Bz = 40G and Δx ≈ 104 km). Then the electric field parallel to the magnetic fields E∥ calculated from Coulomb’s law from this σ is found to be far greater than the Dreicer field, and accelerates electrons and protons. Thus the horizontally inflowing Poynting energy flux in area Sx is immediately converted to the kinetic energy of electron beams along the magnetic field in area Sz; BVxSx/4π=12menVbeam3Sz with Sx/Sz ≈ 4. The particle beam energy flux cannot exceed the Poynting energy flux however large E∥ may be. The total energy can be supplied by 10 keV electrons and nbeam = 2 × 107 cm-3 for Vx = 40 km s-1. This inflow velocity Vx, though restricted by the rising prominence speed, explains the short flare duration consistent to observations. The electron beam flux nbeamVbeam will be simultaneously and co-spatially compensated by the slowly back-flowing bulk electrons, avoiding possible enormous charge pile-up. Instead of the conventional diffusion region, which contains serious difficulties if there is the shear as one should normally expect, we propose

  9. Conversion of lignocellulosic biomass into its molecular components by sequential combination of organic acid and base

    NASA Astrophysics Data System (ADS)

    Noda, Yu

    The primary objective of this research is to explore a new concept of converting lignocellulosic biomass into liquid organic products via hydrolysis by sequentially combining acid and base treatments. The concept was examined by studying two-step hydrolytic reactions of biomass (spruce) using oxialic acid (OA) and tetramethylammonium hydroxide (TMAH) at moderate reaction temperatures below 200 °C. Different selectivity of C-O bond cleavage of hemicellulose, cellulose, and lignin between the reactions with OA and TMAH was demonstrated, and the sequential combination of OA and TMAH treatments exhibited an enhancing effect on conversion of biomass, which proves the promise of the proposed concept. A similar enhancing effect of combination was further confirmed in the reactions with mineral acid and base. Interestingly, characterization of solid residue from reactions of biomass and further investigation of the reactions of commercial cellulose revealed that the A-B sequence (the first reaction with OA and the second with TMAH) enhanced the conversion of cellulose at the second step with TMAH. It was suggested from the NMR and XRD study of solid residues that this enhancement was caused by the reduction of crystallinity of cellulose by the first reaction with OA. This effect was shown to be an interesting feature of A-B treatment sequence for converting lignocellulosic biomass. To improve the yield of monomeric sugars, the effect of adding organic solvents to the system was also studied. No improvement on sugar yield was observed under the explored conditions. However, it was shown that some furans and phenols can be directly formed from the reactions of biomass in the binary solvent system, which may be beneficial for producing more value-added chemicals from biomass.

  10. Palmprint Recognition Based on Complete Direction Representation.

    PubMed

    Jia, Wei; Zhang, Bob; Lu, Jingting; Zhu, Yihai; Zhao, Yang; Zuo, Wangmeng; Ling, Haibin

    2017-05-18

    Direction information serves as one of the most important features for palmprint recognition. In the past decade, many effective direction representation (DR)-based methods have been proposed and achieved promising recognition performance. However, due to an incomplete understanding for DR, these methods only extract DR in one direction level and one scale. Hence, they did not fully utilized all potentials of DR. In addition, most researchers only focused on the DR extraction in spatial coding domain, and rarely considered the methods in frequency domain. In this paper, we propose a general framework for DR-based method named Complete Direction Representation (CDR), which reveals DR by a comprehensive and complete way. Different from traditional methods, CDR emphasizes the use of direction information with strategies of multi-scale, multi-direction level, multi-region, as well as feature selection or learning. This way, CDR subsumes previous methods as special cases. Moreover, thanks to its new insight, CDR can guide the design of new DR-based methods toward better performance. Motived this way, we propose a novel palmprint recognition algorithm in frequency domain. Firstly, we extract CDR using multi-scale modified finite radon transformation (MFRAT). Then, an effective correlation filter, namely Band-Limited Phase-Only Correlation (BLPOC), is explored for pattern matching. To remove feature redundancy, the Sequential Forward Selection (SFS) method is used to select a small number of CDR images. Finally, the matching scores obtained from different selected features are integrated using score-level-fusion. Experiments demonstrate that our method can achieve better recognition accuracy than the other state-of-the-art methods. More importantly, it has fast matching speed, making it quite suitable for the large-scale identification applications.

  11. 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.

  12. Direct micellar systems as a tool to improve the efficiency of aromatic substrate conversion for fine chemicals production.

    PubMed

    Berti, D; Randazzo, D; Briganti, F; Baglioni, P; Scozzafava, A; Di Gennaro, P; Galli, E; Bestetti, G

    2000-04-01

    Whole-cell bioconversion of naphthalene to (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene by Escherichia coli JM109(pPS1778) recombinant strain, carrying naphthalene dioxygenase and regulatory genes cloned from Pseudomonas fluorescens N3, in direct micellar systems is optimized as an example of fine chemicals bioproduction from scarcely water-soluble substrates. The oxygen insertion into the aromatic substrate, which stops at the enantiomerically pure cis dihydroxylated product, is performed in direct microemulsion systems, where a non-ionic surfactant stabilizes naphthalene containing oil droplets in an aqueous medium. These media provide an increased substrate solubility so that a homogeneous reaction can be carried out, while not affecting bacteria viability and performances. The influence of the chemical nature of the oil is investigated. The phase behavior of the direct microemulsion system was monitored for three different oils as a function their volume fraction and characterized through light scattering. The addition of isopropyl palmitate, oleic acid, or glyceryl trioleate, 0.6-1.2% v/v to the micellar systems, led to an increase of the substrate concentration in the solution and particularly its bioavailability, allowing faster catalytic conversions. All these systems resulted in being suitable for catalytic conversions of aromatic compounds. Although the nature of the oil does have a deep effect on the phase behavior of the micellar systems, in the present investigation no differences in the yields and in the rates of product formation of the enzymatic system were observed on changing the oil, thus showing that in this case the substrate concentration or bioavailability is not the rate-limiting step.

  13. Desing and Implementation of the Image Format Batch-Conversion Software Based on ImageJ

    NASA Astrophysics Data System (ADS)

    Xu, Jun; Chen, Dong

    2008-09-01

    The authors introduce ImageJ which is the open source and pure Java language image processing procedure and how to use ImageJ package for secondary development. Using the package, they have realized the format conversion from TIFF and SPE that acquised from WinView software to FITS. And based on this, put forward on the method how to use the package to achieve other format conversion as a separate or batch.

  14. A direct current rectification scheme for microwave space power conversion using traveling wave electron acceleration

    NASA Technical Reports Server (NTRS)

    Manning, Robert M.

    1993-01-01

    The formation of the Vision-21 conference held three years ago allowed the present author to reflect and speculate on the problem of converting electromagnetic energy to a direct current by essentially reversing the process used in traveling wave tubes that converts energy in the form of a direct current to electromagnetic energy. The idea was to use the electric field of the electromagnetic wave to produce electrons through the field emission process and accelerate these electrons by the same field to produce an electric current across a large potential difference. The acceleration process was that of cyclotron auto-resonance. Since that time, this rather speculative ideas has been developed into a method that shows great promise and for which a patent is pending and a prototype design will be demonstrated in a potential laser power beaming application. From the point of view of the author, a forum such as Vision-21 is becoming an essential component in the rather conservative climate in which our initiatives for space exploration are presently formed. Exchanges such as Vision-21 not only allows us to deviate from the 'by-the-book' approach and rediscover the ability and power in imagination, but provides for the discussion of ideas hitherto considered 'crazy' so that they may be given the change to transcend from the level of eccentricity to applicability.

  15. 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.

  16. Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure.

    PubMed

    May, Matthias M; Lewerenz, Hans-Joachim; Lackner, David; Dimroth, Frank; Hannappel, Thomas

    2015-09-15

    Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.

  17. Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure

    PubMed Central

    May, Matthias M.; Lewerenz, Hans-Joachim; Lackner, David; Dimroth, Frank; Hannappel, Thomas

    2015-01-01

    Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators. PMID:26369620

  18. Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure

    NASA Astrophysics Data System (ADS)

    May, Matthias M.; Lewerenz, Hans-Joachim; Lackner, David; Dimroth, Frank; Hannappel, Thomas

    2015-09-01

    Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.

  19. Direct Conversion of Cellulose into Ethyl Lactate in Supercritical Ethanol-Water Solutions.

    PubMed

    Yang, Lisha; Yang, Xiaokun; Tian, Elli; Lin, Hongfei

    2016-01-08

    Biomass-derived ethyl lactate is a green solvent with a growing market as the replacement for petroleum-derived toxic organic solvents. Here we report, for the first time, the production of ethyl lactate directly from cellulose with the mesoporous Zr-SBA-15 silicate catalyst in a supercritical mixture of ethanol and water. The relatively strong Lewis and weak Brønsted acid sites on the catalyst, as well as the surface hydrophobicity, were beneficial to the reaction and led to synergy during consecutive reactions, such as depolymerization, retro-aldol condensation, and esterification. Under the optimum reaction conditions, ∼33 % yield of ethyl lactate was produced from cellulose with the Zr-SBA-15 catalyst at 260 °C in supercritical 95:5 (w/w) ethanol/water.

  20. DESIGN OF 2.4 GHZ CMOS DIRECT CONVERSION LNA AND MIXER COMBINATION FOR WIRLESS DATA LINK TRANSCEIVER.

    SciTech Connect

    ZHAO, D.; OCONNOR, P.

    2002-04-10

    Three LNA and mixer combinations in 0.6{micro}m and 0.4{micro}m standard CMOS processes for direct-conversion receiver of 2.4GHz ISM band short-range wireless data-link applications are described in this paper. Taking low power dissipation as first consideration, these designs, employing differential common-source LNA and double balanced mixer architectures, achieve total conversion gain as high as 42.4dB, DSB noise figure as low as 9.5dB, output-referred IP3 as high as of 21.3dBm at about 4mA DC current consumption. This proves it is possible to apply standard CMOS process to implement receiver front-end with low power dissipation for this kind of application, but gain changeable LNA is needed to combat the dominant flicker noise of the mixer in order to achieve acceptable sensitivity and dynamic range at the same time.

  1. Direct conversion of silver complexes to nanoscale hexagonal columns on a copper alloy for plasmonic applications.

    PubMed

    Yamamoto, Yuko S; Hasegawa, Katsuyuki; Hasegawa, Yuuki; Takahashi, Naoshi; Kitahama, Yasutaka; Fukuoka, Satoshi; Murase, Norio; Baba, Yoshinobu; Ozaki, Yukihiro; Itoh, Tamitake

    2013-09-21

    We introduced a novel method for the rapid synthesis of silver nanohexagonal thin columns from an aqueous mixture of sodium thiosulfate (Na2S2O3) and silver chloride (AgCl) simply added to a phosphor bronze substrate. The reaction is based on galvanic displacement and the products are potentially useful for plasmonic applications.

  2. Discrete directional wavelet bases for image compression

    NASA Astrophysics Data System (ADS)

    Dragotti, Pier L.; Velisavljevic, Vladan; Vetterli, Martin; Beferull-Lozano, Baltasar

    2003-06-01

    The application of the wavelet transform in image processing is most frequently based on a separable construction. Lines and columns in an image are treated independently and the basis functions are simply products of the corresponding one dimensional functions. Such method keeps simplicity in design and computation, but is not capable of capturing properly all the properties of an image. In this paper, a new truly separable discrete multi-directional transform is proposed with a subsampling method based on lattice theory. Alternatively, the subsampling can be omitted and this leads to a multi-directional frame. This transform can be applied in many areas like denoising, non-linear approximation and compression. The results on non-linear approximation and denoising show very interesting gains compared to the standard two-dimensional analysis.

  3. Gene conversion and deletion frequencies during double-strand break repair in human cells are controlled by the distance between direct repeats.

    PubMed

    Schildkraut, Ezra; Miller, Cheryl A; Nickoloff, Jac A

    2005-01-01

    Homologous recombination (HR) repairs DNA double-strand breaks and maintains genome stability. HR between linked, direct repeats can occur by gene conversion without an associated crossover that maintains the gross repeat structure. Alternatively, direct repeat HR can occur by gene conversion with a crossover, or by single-strand annealing (SSA), both of which delete one repeat and the sequences between the repeats. Prior studies of different repeat structures in yeast and mammalian cells revealed disparate conversion:deletion ratios. Here, we show that a key factor controlling this ratio is the distance between the repeats, with conversion frequency increasing linearly with the distances from 850 to 3800 bp. Deletions are thought to arise primarily by SSA, which involves extensive end-processing to reveal complementary single-strands in each repeat. The results can be explained by a model in which strand-invasion leading to gene conversion competes more effectively with SSA as more extensive end-processing is required for SSA. We hypothesized that a transcription unit between repeats would inhibit end-processing and SSA, thereby increasing the fraction of conversions. However, conversion frequencies were identical for direct repeats separated by 3800 bp of transcriptionally silent or active DNA, indicating that end-processing and SSA are not affected by transcription.

  4. 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.

  5. Direct conversion of solid hydrocarbons in a molten carbonate fuel cell

    NASA Astrophysics Data System (ADS)

    Predtechensky, M. R.; Varlamov, Yu. D.; Ul'Yankin, S. N.; Dubov, Yu. D.

    2009-12-01

    Electrical characteristics of a molten carbonate fuel cell allowing direct electrochemical oxidation of dispersed hydrocarbons have been examined. As the fuel, graphite, anthracite, and cannel coal samples were used. Data illustrating the effect of electrolyte temperature, fuel type and dispersion, and also reactant gas mixture composition on the performance characteristics of the fuel cell, were obtained. Correlation between the specific characteristics of the fuel cell and the hydrogen content of fuel material was established. The maximum current-density values were achieved with hydrogen-rich cannel coal. For dispersed fuel samples, interparticle contact losses were found to have influence on the cell-generated voltage. The maximum cell opencircuit voltage was reached with stoichiometric oxygen-carbon dioxide mixture blown into the cathode. Yet, the largest current-density values were obtained when carbon dioxide lean mixtures were used. Even at zero carbon dioxide concentration the range of cathode polarizations was less than that observed with stoichiometric mixture. The processes proceeding in the cathode and anode packs of the fuel cell are believed to be interrelated processes. In a model fuel cell fueled with dispersed coal, current densities up to 140 mA/cm2 and specific powers up to 70 mW/cm2 were achieved.

  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. 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.

  8. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    SciTech Connect

    Narayan, Jagdish Bhaumik, Anagh

    2016-02-01

    We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

  9. Dynamics-based centrality for directed networks

    NASA Astrophysics Data System (ADS)

    Masuda, Naoki; Kori, Hiroshi

    2010-11-01

    Determining the relative importance of nodes in directed networks is important in, for example, ranking websites, publications, and sports teams, and for understanding signal flows in systems biology. A prevailing centrality measure in this respect is the PageRank. In this work, we focus on another class of centrality derived from the Laplacian of the network. We extend the Laplacian-based centrality, which has mainly been applied to strongly connected networks, to the case of general directed networks such that we can quantitatively compare arbitrary nodes. Toward this end, we adopt the idea used in the PageRank to introduce global connectivity between all the pairs of nodes with a certain strength. Numerical simulations are carried out on some networks. We also offer interpretations of the Laplacian-based centrality for general directed networks in terms of various dynamical and structural properties of networks. Importantly, the Laplacian-based centrality defined as the stationary density of the continuous-time random walk with random jumps is shown to be equivalent to the absorption probability of the random walk with sinks at each node but without random jumps. Similarly, the proposed centrality represents the importance of nodes in dynamics on the original network supplied with sinks but not with random jumps.

  10. From Carbon-Based Nanotubes to Nanocages for Advanced Energy Conversion and Storage.

    PubMed

    Wu, Qiang; Yang, Lijun; Wang, Xizhang; Hu, Zheng

    2017-02-21

    Carbon-based nanomaterials have been the focus of research interests in the past 30 years due to their abundant microstructures and morphologies, excellent properties, and wide potential applications, as landmarked by 0D fullerene, 1D nanotubes, and 2D graphene. With the availability of high specific surface area (SSA), well-balanced pore distribution, high conductivity, and tunable wettability, carbon-based nanomaterials are highly expected as advanced materials for energy conversion and storage to meet the increasing demands for clean and renewable energies. In this context, attention is usually attracted by the star material of graphene in recent years. In this Account, we overview our studies on carbon-based nanotubes to nanocages for energy conversion and storage, including their synthesis, performances, and related mechanisms. The two carbon nanostructures have the common features of interior cavity, high conductivity, and easy doping but much different SSAs and pore distributions, leading to different performances. We demonstrated a six-membered-ring-based growth mechanism of carbon nanotubes (CNTs) with benzene precursor based on the structural similarity of the benzene ring to the building unit of CNTs. By this mechanism, nitrogen-doped CNTs (NCNTs) with homogeneous N distribution and predominant pyridinic N were obtained with pyridine precursor, providing a new kind of support for convenient surface functionalization via N-participation. Accordingly, various transition-metal nanoparticles were directly immobilized onto NCNTs without premodification. The so-constructed catalysts featured high dispersion, narrow size distribution and tunable composition, which presented superior catalytic performances for energy conversions, for example, the oxygen reduction reaction (ORR) and methanol oxidation in fuel cells. With the advent of the new field of carbon-based metal-free electrocatalysts, we first extended ORR catalysts from the electron-rich N-doped to the

  11. Alteration of gene conversion patterns in Sordaria fimicola by supplementation with DNA bases.

    PubMed

    Kitani, Y; Olive, L S

    1970-08-01

    Supplementation with DNA bases in crosses of Sordaria fimicola heterozygous for spore color markers (g(1), h(2)) within the gray-spore (g) locus has been found to cause significant alterations in patterns of gene conversion at the two mutant sites. Each base had its own characteristic effect in altering the conversion pattern, and responses of the two mutant sites to the four bases were different in several ways. Also, the responses of the two involved chromatids of the meiotic bivalent were different.

  12. ALTERATION OF GENE CONVERSION PATTERNS IN Sordaria fimicola BY SUPPLEMENTATION WITH DNA BASES*

    PubMed Central

    Kitani, Y.; Olive, Lindsay S.

    1970-01-01

    Supplementation with DNA bases in crosses of Sordaria fimicola heterozygous for spore color markers (g1, h2) within the gray-spore (g) locus has been found to cause significant alterations in patterns of gene conversion at the two mutant sites. Each base had its own characteristic effect in altering the conversion pattern, and responses of the two mutant sites to the four bases were different in several ways. Also, the responses of the two involved chromatids of the meiotic bivalent were different. PMID:5273454

  13. A direct assessment of human prion adhered to steel wire using real-time quaking-induced conversion

    PubMed Central

    Mori, Tsuyoshi; Atarashi, Ryuichiro; Furukawa, Kana; Takatsuki, Hanae; Satoh, Katsuya; Sano, Kazunori; Nakagaki, Takehiro; Ishibashi, Daisuke; Ichimiya, Kazuko; Hamada, Masahisa; Nakayama, Takehisa; Nishida, Noriyuki

    2016-01-01

    Accidental transmission of prions during neurosurgery has been reported as a consequence of re-using contaminated surgical instruments. Several decontamination methods have been studied using the 263K-hamster prion; however, no studies have directly evaluated human prions. A newly developed in vitro amplification system, designated real-time quaking-induced conversion (RT-QuIC), has allowed the activity of abnormal prion proteins to be assessed within a few days. RT-QuIC using human recombinant prion protein (PrP) showed high sensitivity for prions as the detection limit of our assay was estimated as 0.12 fg of active prions. We applied this method to detect human prion activity on stainless steel wire. When we put wires contaminated with human Creutzfeldt–Jakob disease brain tissue directly into the test tube, typical PrP-amyloid formation was observed within 48 hours, and we could detect the activity of prions at 50% seeding dose on the wire from 102.8 to 105.8 SD50. Using this method, we also confirmed that the seeding activities on the wire were removed following treatment with NaOH. As seeding activity closely correlated with the infectivity of prions using the bioassay, this wire-QuIC assay will be useful for the direct evaluation of decontamination methods for human prions. PMID:27112110

  14. Nuclear Propulsion through Direct Conversion of Fusion Energy: The Fusion Driven Rocket

    NASA Technical Reports Server (NTRS)

    Slough, John; Pancotti, Anthony; Kirtley, David; Pihl, Christopher; Pfaff, Michael

    2012-01-01

    The future of manned space exploration and development of space depends critically on the creation of a dramatically more proficient propulsion architecture for in-space transportation. A very persuasive reason for investigating the applicability of nuclear power in rockets is the vast energy density gain of nuclear fuel when compared to chemical combustion energy. Current nuclear fusion efforts have focused on the generation of electric grid power and are wholly inappropriate for space transportation as the application of a reactor based fusion-electric system creates a colossal mass and heat rejection problem for space application.

  15. Recent Advances in Atomic Metal Doping of Carbon-based Nanomaterials for Energy Conversion.

    PubMed

    Bayatsarmadi, Bita; Zheng, Yao; Vasileff, Anthony; Qiao, Shi-Zhang

    2017-04-12

    Nanostructured metal-contained catalysts are one of the most widely used types of catalysts applied to facilitate some of sluggish electrochemical reactions. However, the high activity of these catalysts cannot be sustained over a variety of pH ranges. In an effort to develop highly active and stable metal-contained catalysts, various approaches have been pursued with an emphasis on metal particle size reduction and doping on carbon-based supports. These techniques enhances the metal-support interactions, originating from the chemical bonding effect between the metal dopants and carbon support and the associated interface, as well as the charge transfer between the atomic metal species and carbon framework. This provides an opportunity to tune the well-defined metal active centers and optimize their activity, selectivity and stability of this type of (electro)catalyst. Herein, recent advances in synthesis strategies, characterization and catalytic performance of single atom metal dopants on carbon-based nanomaterials are highlighted with attempts to understand the electronic structure and spatial arrangement of individual atoms as well as their interaction with the supports. Applications of these new materials in a wide range of potential electrocatalytic processes in renewable energy conversion systems are also discussed with emphasis on future directions in this active field of research.

  16. Multifunctional switching unit for add/drop, wavelength conversion, format conversion, and WDM multicast based on bidirectional LCoS and SOA-loop architecture.

    PubMed

    Wang, Danshi; Zhang, Min; Qin, Jun; Lu, Guo-Wei; Wang, Hongxiang; Huang, Shanguo

    2014-09-08

    We propose a multifunctional optical switching unit based on the bidirectional liquid crystal on silicon (LCoS) and semiconductor optical amplifier (SOA) architecture. Add/drop, wavelength conversion, format conversion, and WDM multicast are experimentally demonstrated. Due to the bidirectional characteristic, the LCoS device cannot only multiplex the input signals, but also de-multiplex the converted signals. Dual-channel wavelength conversion and format conversion from 2 × 25Gbps differential quadrature phase-shift-keying (DQPSK) to 2 × 12.5Gbps differential phase-shift-keying (DPSK) based on four-wave mixing (FWM) in SOA is obtained with only one pump. One-to-six WDM multicast of 25Gbps DQPSK signals with two pumps is also achieved. All of the multicast channels are with a power penalty less than 1.1 dB at FEC threshold of 3.8 × 10⁻³.

  17. Systems definition space based power conversion systems: Executive summary

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Potential space-located systems for the generation of electrical power for use on earth were investigated. These systems were of three basic types: (1) systems producing electrical power from solar energy; (2) systems producing electrical power from nuclear reactors; (3) systems for augmenting ground-based solar power plants by orbital sunlight reflectors. Configurations implementing these concepts were developed through an optimization process intended to yield the lowest cost for each. A complete program was developed for each concept, identifying required production rates, quantities of launches, required facilities, etc. Each program was costed in order to provide the electric power cost appropriate to each concept.

  18. Directed Nanoscale Assembly of Graphene Based Materials

    NASA Astrophysics Data System (ADS)

    Kim, Sang Ouk

    Graphene based materials, including fullerene, carbon nanotubes and graphene, are two-dimensional polymeric materials consisting of sp2 hybrid carbons. Those carbon materials have attracted enormous research attention for their outstanding material properties along with molecular scale dimension. The optimized utilization of those materials in various application fields inevitably requires the subtle controllability of their structures and properties. In this presentation, our research achievements associated to directed nanoscale assembly of B- or N-doped graphene based materials will be introduced. Graphene based materials can be efficiently processed into various three-dimensional structures via self-assembly principles. Those carbon assembled structures with extremely large surface and high electro-conductivity are potentially useful for energy and environmental applications. Aqueous dispersion of graphene oxide shows liquid crystalline phase, whose spontaneous molecular ordering is useful for display or fiber spinning. Along with the structure control by directed nanoscale assembly, substitutional doping of graphene based materials with B- or N- can be attained via various chemical treatment methods. The resultant chemically modified carbon materials with tunable workfunction, charge carrier density and enhanced surface activity could be employed for various nanomaterials and nanodevices for improved functionalities and performances.

  19. Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors

    PubMed Central

    Kasap, Safa; Frey, Joel B.; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S.; Rowlands, John A.

    2011-01-01

    In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been

  20. Amorphous and polycrystalline photoconductors for direct conversion flat panel x-ray image sensors.

    PubMed

    Kasap, Safa; Frey, Joel B; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S; Rowlands, John A

    2011-01-01

    In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI(2) and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been

  1. Direct Conversion of Hydride- to Siloxane-Terminated Silicon Quantum Dots

    SciTech Connect

    Anderson, Ryan T.; Zang, Xiaoning; Fernando, Roshan; Dzara, Michael J.; Ngo, Chilan; Sharps, Meredith; Pinals, Rebecca; Pylypenko, Svitlana; Lusk, Mark T.; Sellinger, Alan

    2016-11-17

    Peripheral surface functionalization of hydride-terminated silicon quantum dots (SiQD) is necessary in order to minimize their oxidation/aggregation and allow for solution processability. Historically thermal hydrosilylation addition of alkenes and alkynes across the Si-H surface to form Si-C bonds has been the primary method to achieve this. Here we demonstrate a mild alternative approach to functionalize hydride-terminated SiQDs using bulky silanols in the presence of free-radical initiators to form stable siloxane (~Si-O-SiR3) surfaces with hydrogen gas as a byproduct. This offers an alternative to existing methods of forming siloxane surfaces that require corrosive Si-Cl based chemistry with HCl byproducts. A 52 nm blue shift in the photoluminescent spectra of siloxane versus alkyl-functionalized SiQDs is observed that we explain using computational theory. Model compound synthesis of silane and silsesquioxane analogues is used to optimize surface chemistry and elucidate reaction mechanisms. Thorough characterization on the extent of siloxane surface coverage is provided using FTIR and XPS. TEM is used to demonstrate SiQD size and integrity after surface chemistry and product isolation.

  2. Direct conversion of hydride- to siloxane-terminated silicon quantum dots

    DOE PAGES

    Anderson, Ryan T.; Zang, Xiaoning; Fernando, Roshan; ...

    2016-10-20

    Here, peripheral surface functionalization of hydride-terminated silicon quantum dots (SiQD) is necessary in order to minimize their oxidation/aggregation and allow for solution processability. Historically thermal hydrosilylation addition of alkenes and alkynes across the Si-H surface to form Si-C bonds has been the primary method to achieve this. Here we demonstrate a mild alternative approach to functionalize hydride-terminated SiQDs using bulky silanols in the presence of free-radical initiators to form stable siloxane (~Si-O-SiR3) surfaces with hydrogen gas as a byproduct. This offers an alternative to existing methods of forming siloxane surfaces that require corrosive Si-Cl based chemistry with HCl byproducts. Amore » 52 nm blue shift in the photoluminescent spectra of siloxane versus alkyl-functionalized SiQDs is observed that we explain using computational theory. Model compound synthesis of silane and silsesquioxane analogues is used to optimize surface chemistry and elucidate reaction mechanisms. Thorough characterization on the extent of siloxane surface coverage is provided using FTIR and XPS. As a result, TEM is used to demonstrate SiQD size and integrity after surface chemistry and product isolation.« less

  3. 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.

  4. Silicon nitride grating waveguide based directional coupler

    NASA Astrophysics Data System (ADS)

    Feng, Jijun; Li, Anyuan; Akimoto, Ryoichi; Zeng, Heping

    2016-10-01

    Silicon nitride is a promising wave-guiding material for integrated photonics applications with a wide transparency bandwidth from visible to mid-infrared, with a superior performance in fiber-coupling and propagation losses, more tolerant fabrication process to the structure parameters variation and compatible with the CMOS technology. Directional coupler (DC) is very popular for realizing beam splitter because of its structural simplicity and no excess loss intrinsically. Here, a conventional silicon nitride directional coupler, three-dimensional vertical coupler, and grating waveguide assisted coupler are designed and fabricated, and compared with each other. A grating waveguide based coupler with a period of 300 nm and coupling length of 26 um, can realize a wideband 3-dB splitter for the wavelength in the range from 1540 to 1620 nm, for a transverse electric (TE) polarized wave. With further optimization of the grating period and duty cycle, the device performance can be further improved with a wider bandwidth.

  5. Format conversion between CAD data and GIS data based on ArcGIS

    NASA Astrophysics Data System (ADS)

    Xie, Qingqing; Wei, Bo; Zhang, Kailin; Wang, Zhichao

    2015-12-01

    To make full use of the data resources and realize a sharing for the different types of data in different industries, a method of format conversion between CAD data and GIS data based on ArcGIS was proposed. To keep the integrity of the converted data, some key steps to process CAD data before conversion were made in AutoCAD. For examples, deleting unnecessary elements such as title, border and legend avoided the appearance of unnecessary elements after conversion, as layering data again by a national standard avoided the different types of elements to appear in a same layer after conversion. In ArcGIS, converting CAD data to GIS data was executed by the correspondence of graphic element classification between AutoCAD and ArcGIS. In addition, an empty geographic database and feature set was required to create in ArcGIS for storing the text data of CAD data. The experimental results show that the proposed method avoids a large amount of editing work in data conversion and maintains the integrity of spatial data and attribute data between before and after conversion.

  6. An XML based middleware for ECG format conversion.

    PubMed

    Li, Xuchen; Vojisavljevic, Vuk; Fang, Qiang

    2009-01-01

    With the rapid development of information and communication technologies, various e-health solutions have been proposed. The digitized medical images as well as the mono-dimension medical signals are two major forms of medical information that are stored and manipulated within an electronic medical environment. Though a variety of industrial and international standards such as DICOM and HL7 have been proposed, many proprietary formats are still pervasively used by many Hospital Information System (HIS) and Picture Archiving and Communication System (PACS) vendors. Those proprietary formats are the big hurdle to form a nationwide or even worldwide e-health network. Thus there is an imperative need to solve the medical data integration problem. Moreover, many small clinics, many hospitals in developing countries and some regional hospitals in developed countries, which have limited budget, have been shunned from embracing the latest medical information technologies due to their high costs. In this paper, we propose an XML based middleware which acts as a translation engine to seamlessly integrate clinical ECG data from a variety of proprietary data formats. Furthermore, this ECG translation engine is designed in a way that it can be integrated into an existing PACS to provide a low cost medical information integration and storage solution.

  7. Twisted Savonius turbine based marine current energy conversion system

    NASA Astrophysics Data System (ADS)

    Hassan, Md. Imtiaj

    The Ocean Network Seafloor Instrumentation (ONSFI) Project is a multidisciplinary research and development project that aims to design, fabricate and validate a proof-of-concept seafloor array of wireless marine sensors for use in monitoring seabed processes. The sensor pods, known as Seaformatics, will be powered by ocean bottom currents and will be able to communicate with each other and to the Internet through surface master units to facilitate observation of the ocean floor from the shore. This thesis explores the use of the twisted Savonius turbine as a means of converting the kinetic energy of the free flowing water into electrical energy for the pods. This will eliminate the need for battery replacement. A physical model of the turbine was constructed and tested in the Water Flume at the Marine Institute of Memorial University and in the Wind Tunnel in the Engineering Building at Memorial University. A mathematical model of the turbine was constructed in SolidWorks. This was tested in the Computational Fluid Dynamics or CFD software FLOW-3D. Experimental results were compared with CFD results and the agreement was reasonable. A twisted Savonius turbine emulator was developed to test a dc-dc boost converter. A low cost microcontroller based MPPT algorithm was developed to obtain maximum power from the turbine. Overall the thesis shows that the twisted Savonius turbine can provide the power needed by the sensor pods. It also shows that CFD is a viable way to study the performance of the Savonius type of turbine.

  8. A new direct pixel-based focusing method for medical ultrasound imaging: preliminary results

    NASA Astrophysics Data System (ADS)

    Lee, YuHwa; Piao, Chunsheng; Kim, TaeWan; Chang, Jin Ho; Song, Tai-Kyong; Yoo, Yangmo

    2011-03-01

    In medical ultrasound imaging, scan conversion is used to geometrically transform polar coordinate ultrasound data into Cartesian raster data for display. In scan conversion, Moiré undersampling artifacts can be avoided by using various interpolation techniques such as nearest neighbor and bilinear. However, this interpolation-based scan conversion introduces blurring of fine details in ultrasound images. In this paper, a new beamforming technique, named compounded direct pixel beamforming (CDPB), is proposed to remove blurring artifacts from scan conversion. In CDPB, receive focusing is performed directly on each display pixel in Cartesian coordinates with raw radio-frequency (RF) data from two adjacent transmit firings so that artifacts from scan conversion can be substantially removed. To evaluate the proposed CDPB method, 64-channel pre-beamformed RF data were captured by a commercial ultrasound machine (SA-9900, Medison Corp., Seoul, Korea) from a tissue mimicking phantom (ATS Laboratories, Bridgeport, CT, USA). To quantify the performance of the proposed method, the information entropy contrast (IEC) value was measured. From the experiments, the proposed method provided IEC improvement by 2.8 over the conventional scan conversion method. These results indicate that the proposed new beamforming method could be used for enhancing the image quality in medical ultrasound imaging.

  9. Development of rapidly fermenting strains of Saccharomyces diastaticus for direct conversion of starch and dextrins to ethanol

    SciTech Connect

    Laluce, C.; Mattoon, J.R.

    1984-07-01

    Alcoholic fermentation, growth, and glucoamylase production by 12 strains of Saccharomyces diastaticus were compared by using starch and dextrins as substrates. Haploid progeny produced from a rapidly fermenting strain, SD2, were used for hybridization with other S. diastaticus and Saccharomyces cerevisiae haploids. Alcoholic fermentation and enzyme production by hybrid diploids and their haploid parents were evaluated. Although the dosage of the STA or DEX (starch or dextrin fermentation) genes may enhance ethanol production, epistatic effects in certain strain combinations caused decreases in starch-fermenting activity. Both the nature of the starch or dextrin used and the fermentation medium pH had substantial effects on alcohol production. Commercial dextrin was not as good a substrate as dextrins prepared by digesting starch with ..cap alpha..-amylase. Crude manioc starch digested by ..cap alpha..-amylase was fermented directly by selected hybrids with almost 100% conversion efficiency. The manioc preparation contained adequate minerals and growth factors. This procedure should be suitable for direct commercial application in manioc-producing regions in Brazil and elsewhere. A rapidly fermenting haploid strain, SD2-A8, descended from strain SD2, contains two unlinked genes controlling formation of extracellular amylase. A convenient method for detecting these genes (STA genes) in replica plates containing large numbers of meiotic progeny was developed.

  10. Directed evolution of phenylacetone monooxygenase as an active catalyst for the Baeyer-Villiger conversion of cyclohexanone to caprolactone.

    PubMed

    Parra, Loreto P; Acevedo, Juan P; Reetz, Manfred T

    2015-07-01

    Phenylacetone monooxygenase (PAMO) is an exceptionally robust Baeyer-Villiger monooxygenase, which makes it ideal for potential industrial applications. However, its substrate scope is limited, unreactive cyclohexanone being a prominent example. Such a limitation is unfortunate, because this particular transformation in an ecologically viable manner would be highly desirable, the lactone and the respective lactam being of considerable interest as monomers in polymer science. We have applied directed evolution in search of an active mutant for this valuable C-C activating reaction. Using iterative saturation mutagenesis (ISM), several active mutants were evolved, with only a minimal trade-off in terms of stability. The best mutants allow for quantitative conversion of 2 mM cyclohexanone within 1 h reaction time. In order to circumvent the NADP(+) regeneration problem, whole E. coli resting cells were successfully applied. Molecular dynamics simulations and induced fit docking throw light on the origin of enhanced PAMO activity. The PAMO mutants constitute ideal starting points for future directed evolution optimization necessary for an industrial process. © 2015 Wiley Periodicals, Inc.

  11. Development of Rapidly Fermenting Strains of Saccharomyces diastaticus for Direct Conversion of Starch and Dextrins to Ethanol

    PubMed Central

    Laluce, Cecilia; Mattoon, James R.

    1984-01-01

    Alcoholic fermentation, growth, and glucoamylase production by 12 strains of Saccharomyces diastaticus were compared by using starch and dextrins as substrates. Haploid progeny produced from a rapidly fermenting strain, SD2, were used for hybridization with other S. diastaticus and Saccharomyces cerevisiae haploids. Alcoholic fermentation and enzyme production by hybrid diploids and their haploid parents were evaluated. Although the dosage of the STA or DEX (starch or dextrin fermentation) genes may enhance ethanol production, epistatic effects in certain strain combinations caused decreases in starch-fermenting activity. Both the nature of the starch or dextrin used and the fermentation medium pH had substantial effects on alcohol production. Commercial dextrin was not as good a substrate as dextrins prepared by digesting starch with α-amylase. Crude manioc starch digested by α-amylase was fermented directly by selected hybrids with almost 100% conversion efficiency. The manioc preparation contained adequate minerals and growth factors. This procedure should be suitable for direct commercial application in manioc-producing regions in Brazil and elsewhere. A rapidly fermenting haploid strain, SD2-A8, descended from strain SD2, contains two unlinked genes controlling formation of extracellular amylase. A convenient method for detecting these genes (STA genes) in replica plates containing large numbers of meiotic progeny was developed. Images PMID:16346584

  12. Evidence for a direct conversion between two tubulin polymers--microtubules and helical filaments--in the foraminiferan, Allogromia laticollaris.

    PubMed

    Welnhofer, E A; Travis, J L

    1998-01-01

    In Allogromia, tubulin lattices transform between microtubule and helical filament states. Helical filaments are composed of approximately 10-nm-thick tubulin filaments wound into approximately 30-nm diameter coils. The transition pathway between these two lattice states was examined in vitro in detergent-lysed pseudopods. Microtubules represented the majority of the assembled tubulin polymers in the detergent extracted pseudopodia. However, microtubules transformed into helical filaments upon exposure to 10 mM Ca2+ or 50 mM Mg2+. The conversion of microtubules into helical filaments involved fragmentation of the tubulin lattice and reduction in total polymer length. Divalent cations were required for the maintenance of the helical filament state; their removal resulted in the loss of helical filaments and the re-formation of microtubules. The data support a direct transition model in which the tubulin lattice interconverts between the helical filament and microtubule states, independently of tubulin subunit concentration. We propose a structural model for the direct pathway whereby disruption of longitudinal bonds between tandem tubulin dimers in protofilaments causes the microtubule lattice to unwind into helical filaments--continuous ribbons of laterally connected tubulin dimers--from the microtubule end. Helical filaments may rewind into microtubules as longitudinal intersubunit bonds reform.

  13. Off-axis holographic lens spectrum-splitting photovoltaic system for direct and diffuse solar energy conversion.

    PubMed

    Vorndran, Shelby D; Chrysler, Benjamin; Wheelwright, Brian; Angel, Roger; Holman, Zachary; Kostuk, Raymond

    2016-09-20

    This paper describes a high-efficiency, spectrum-splitting photovoltaic module that uses an off-axis volume holographic lens to focus and disperse incident solar illumination to a rectangular shaped high-bandgap indium gallium phosphide cell surrounded by strips of silicon cells. The holographic lens design allows efficient collection of both direct and diffuse illumination to maximize energy yield. We modeled the volume diffraction characteristics using rigorous coupled-wave analysis, and simulated system performance using nonsequential ray tracing and PV cell data from the literature. Under AM 1.5 illumination conditions the simulated module obtained a 30.6% conversion efficiency. This efficiency is a 19.7% relative improvement compared to the more efficient cell in the system (silicon). The module was also simulated under a typical meteorological year of direct and diffuse irradiance in Tucson, Arizona, and Seattle, Washington. Compared to a flat panel silicon module, the holographic spectrum splitting module obtained a relative improvement in energy yield of 17.1% in Tucson and 14.0% in Seattle. An experimental proof-of-concept volume holographic lens was also fabricated in dichromated gelatin to verify the main characteristics of the system. The lens obtained an average first-order diffraction efficiency of 85.4% across the aperture at 532 nm.

  14. Saliency-based gaze prediction based on head direction.

    PubMed

    Nakashima, Ryoichi; Fang, Yu; Hatori, Yasuhiro; Hiratani, Akinori; Matsumiya, Kazumichi; Kuriki, Ichiro; Shioiri, Satoshi

    2015-12-01

    Despite decades of attempts to create a model for predicting gaze locations by using saliency maps, a highly accurate gaze prediction model for general conditions has yet to be devised. In this study, we propose a gaze prediction method based on head direction that can improve the accuracy of any model. We used a probability distribution of eye position based on head direction (static eye-head coordination) and added this information to a model of saliency-based visual attention. Using empirical data on eye and head directions while observers were viewing natural scenes, we estimated a probability distribution of eye position. We then combined the relationship between eye position and head direction with visual saliency to predict gaze locations. The model showed that information on head direction improved the prediction accuracy. Further, there was no difference in the gaze prediction accuracy between the two models using information on head direction with and without eye-head coordination. Therefore, information on head direction is useful for predicting gaze location when it is available. Furthermore, this gaze prediction model can be applied relatively easily to many daily situations such as during walking. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Inverse design of an ultra-compact broadband optical diode based on asymmetric spatial mode conversion

    NASA Astrophysics Data System (ADS)

    Callewaert, Francois; Butun, Serkan; Li, Zhongyang; Aydin, Koray

    2016-09-01

    The objective-first inverse-design algorithm is used to design an ultra-compact optical diode. Based on silicon and air only, this optical diode relies on asymmetric spatial mode conversion between the left and right ports. The first even mode incident from the left port is transmitted to the right port after being converted into an odd mode. On the other hand, same mode incident from the right port is reflected back by the optical diode dielectric structure. The convergence and performance of the algorithm are studied, along with a transform method that converts continuous permittivity medium into a binary material design. The optimal device is studied with full-wave electromagnetic simulations to compare its behavior under right and left incidences, in 2D and 3D settings as well. A parametric study is designed to understand the impact of the design space size and initial conditions on the optimized devices performance. A broadband optical diode behavior is observed after optimization, with a large rejection ratio between the two transmission directions. This illustrates the potential of the objective-first inverse-design method to design ultra-compact broadband photonic devices.

  16. Inverse design of an ultra-compact broadband optical diode based on asymmetric spatial mode conversion

    PubMed Central

    Callewaert, Francois; Butun, Serkan; Li, Zhongyang; Aydin, Koray

    2016-01-01

    The objective-first inverse-design algorithm is used to design an ultra-compact optical diode. Based on silicon and air only, this optical diode relies on asymmetric spatial mode conversion between the left and right ports. The first even mode incident from the left port is transmitted to the right port after being converted into an odd mode. On the other hand, same mode incident from the right port is reflected back by the optical diode dielectric structure. The convergence and performance of the algorithm are studied, along with a transform method that converts continuous permittivity medium into a binary material design. The optimal device is studied with full-wave electromagnetic simulations to compare its behavior under right and left incidences, in 2D and 3D settings as well. A parametric study is designed to understand the impact of the design space size and initial conditions on the optimized devices performance. A broadband optical diode behavior is observed after optimization, with a large rejection ratio between the two transmission directions. This illustrates the potential of the objective-first inverse-design method to design ultra-compact broadband photonic devices. PMID:27586852

  17. Food waste conversion options in Singapore: environmental impacts based on an LCA perspective.

    PubMed

    Khoo, Hsien H; Lim, Teik Z; Tan, Reginald B H

    2010-02-15

    Proper management and recycling of huge volumes of food waste is one of the challenges faced by Singapore. Semakau island - the only offshore landfill of the nation - only accepts inert, inorganic solid waste and therefore a large bulk of food waste is directed to incinerators. A remaining small percent is sent for recycling via anaerobic digestion (AD), followed by composting of the digestate material. This article investigates the environmental performance of four food waste conversion scenarios - based on a life cycle assessment perspective - taking into account air emissions, useful energy from the incinerators and AD process, as well as carbon dioxide mitigation from the compost products derived from the digestate material and a proposed aerobic composting system. The life cycle impact results were generated for global warming, acidification, eutrophication, photochemical oxidation and energy use. The total normalized results showed that a small-scale proposed aerobic composting system is more environmentally favorable than incinerators, but less ideal compared to the AD process. By making full use of the AD's Recycling Phase II process alone, the Singapore Green Plan's 2012 aim to increase the recycling of food waste to 30% can easily be achieved, along with reduced global warming impacts.

  18. Biofuel cell based on direct bioelectrocatalysis.

    PubMed

    Ramanavicius, Arunas; Kausaite, Asta; Ramanaviciene, Almira

    2005-04-15

    A biofuel cell, consisting of two 3mm diameter carbon rod electrodes and operating at ambient temperature in aqueous solution, pH 6, is described. Biofuel cell based on enzymes able to exchange directly electrons with carbon electrodes was constructed and characterized. Anode of the biofuel cell was based on immobilized Quino-hemoprotein alcohol dehydrogenase from Gluconobacter sp. 33 (QH-ADH), cathode on co-immobilized glucose oxidase from Aspergilus niger (GO(x)) and microperoxidase 8 from the horse heart (MP-8) acting in the consecutive mode. Two enzymes GO(x) and MP-8 applied in the design of biofuel cell cathode were acting in consecutive mode and by hydrogen peroxide oxidized MP-8 was directly accepting electrons from carbon rod electrode. If ethanol was applied as an energy source the maximal open circuit potential of the biofuel cell was -125 mV. If glucose was applied as energy source the open circuit potential of the cell was +145 mV. The maximal open circuit potential (270 mV) was achieved in the presence of extent concentration (over 2 mM) of both substrates (ethanol and glucose). Operational half-life period (tau(1/2)) of the biofuel cell was found to be 2.5 days.

  19. Nurses' fidelity to theory-based core components when implementing Family Health Conversations - a qualitative inquiry.

    PubMed

    Östlund, Ulrika; Bäckström, Britt; Lindh, Viveca; Sundin, Karin; Saveman, Britt-Inger

    2015-09-01

    A family systems nursing intervention, Family Health Conversation, has been developed in Sweden by adapting the Calgary Family Assessment and Intervention Models and the Illness Beliefs Model. The intervention has several theoretical assumptions, and one way translate the theory into practice is to identify core components. This may produce higher levels of fidelity to the intervention. Besides information about how to implement an intervention in accordance to how it was developed, evaluating whether it was actually implemented as intended is important. Accordingly, we describe the nurses' fidelity to the identified core components of Family Health Conversation. Six nurses, working in alternating pairs, conducted Family Health Conversations with seven families in which a family member younger than 65 had suffered a stroke. The intervention contained a series of three-1-hour conversations held at 2-3 week intervals. The nurses followed a conversation structure based on 12 core components identified from theoretical assumptions. The transcripts of the 21 conversations were analysed using manifest qualitative content analysis with a deductive approach. The 'core components' seemed to be useful even if nurses' fidelity varied among the core components. Some components were followed relatively well, but others were not. This indicates that the process for achieving fidelity to the intervention can be improved, and that it is necessary for nurses to continually learn theory and to practise family systems nursing. We suggest this can be accomplished through reflections, role play and training on the core components. Furthermore, as in this study, joint reflections on how the core components have been implemented can lead to deeper understanding and knowledge of how Family Health Conversation can be delivered as intended. © 2014 Nordic College of Caring Science.

  20. Management of marine cage aquaculture. Environmental carrying capacity method based on dry feed conversion rate.

    PubMed

    Cai, Huiwen; Sun, Yinglan

    2007-11-01

    Marine cage aquaculture produces a large amount of waste that is released directly into the environment. To effectively manage the mariculture environment, it is important to determine the carrying capacity of an aquaculture area. In many Asian countries trash fish is dominantly used in marine cage aquaculture, which contains more water than pellet feed. The traditional nutrient loading analysis is for pellet feed not for trash fish feed. So, a more critical analysis is necessary in trash fish feed culturing areas. Corresponding to FCR (feed conversion rate), dry feed conversion rate (DFCR) was used to analyze the nutrient loadings from marine cage aquaculture where trash fish is used. Based on the hydrodynamic model and the mass transport model in Xiangshan Harbor, the relationship between the water quality and the waste discharged from cage aquaculture has been determined. The environmental carrying capacity of the aquaculture sea area was calculated by applying the models noted above. Nitrogen and phosphorus are the water quality parameters considered in this study. The simulated results show that the maximum nitrogen and phosphorus concentrations were 0.216 mg/L and 0.039 mg/L, respectively. In most of the sea area, the nutrient concentrations were higher than the water quality standard. The calculated environmental carrying capacity of nitrogen and phosphorus in Xiangshan Harbor were 1,107.37 t/yr and 134.35 t/yr, respectively. The waste generated from cage culturing in 2000 has already exceeded the environmental carrying capacity. Unconsumed feed has been identified as the most important origin of all pollutants in cage culturing systems. It suggests the importance of increasing the feed utilization and improving the feed composition on the basis of nutrient requirement. For the sustainable development of the aquaculture industry, it is an effective management measure to keep the stocking density and pollution loadings below the environmental carrying

  1. Illustrations for a Competency Based Curriculum Guide: Ethanol Spark Ignition Engine Conversion.

    ERIC Educational Resources Information Center

    Illinois State Board of Education, Springfield. Dept. of Adult, Vocational and Technical Education.

    This document contains 56 illustrations for use in an Illinois-developed competency-based course in ethanol spark ignition engine conversion. Each illustration is related to a specific competency in the course curriculum guide. Illustrations, which include photographs and line drawings, cover some of the following topics: carburetion, compression,…

  2. Illustrations for a Competency Based Curriculum Guide: Ethanol Spark Ignition Engine Conversion.

    ERIC Educational Resources Information Center

    Illinois State Board of Education, Springfield. Dept. of Adult, Vocational and Technical Education.

    This document contains 56 illustrations for use in an Illinois-developed competency-based course in ethanol spark ignition engine conversion. Each illustration is related to a specific competency in the course curriculum guide. Illustrations, which include photographs and line drawings, cover some of the following topics: carburetion, compression,…

  3. Pre-Service Mathematics Teachers' Pattern Conversion Ability: Generating Figural Patterns Based on Number Patterns

    ERIC Educational Resources Information Center

    Kiliç, Çigdem

    2017-01-01

    In that current study, pattern conversion ability of 25 pre-service mathematics teachers (producing figural patterns following number patterns) was investigated. During the study participants were asked to generate figural patterns based on those number patterns. The results of the study indicate that many participants could generate different…

  4. Gallium nitride based power switches for next generation of power conversion

    SciTech Connect

    Chowdhury, S

    2015-03-17

    Power conversion impacts all areas of electricity consumption, including motion control, lighting, air conditioning, and information technology. Si, the workhorse of the industry, has served well so far but reached its material limits. To keep up with the advancement of technologies enabling new conveniences, power conversion techniques need to go through significant transformation that calls for the next generation semiconductor for power switching. SiC and GaN, which have the potential to push the envelope beyond Si providing solutions for the entire range of power conversion at higher efficiencies and reduced form factors. GaN HEMTs have an added advantage over SiC MOSFETs owing to the high-mobility electron channel formed at the AlGaN/GaN interface, which has been the basis of radio frequency amplifiers. GaN has enabled systems that can run with lesser cooling at frequencies at least ten times higher than current Si-based systems, significantly reducing the form factor both electrically (passive components) and mechanically (heat sinks). The high current and voltage required for high power conversion application make the chip area in a lateral topology uneconomical and difficult to manufacture. Vertical GaN devices on bulk GaN substrates complete the portfolio of power switches required to address the power conversion market.

  5. 10Gbit/s all-optical NRZ to RZ conversion based on TOAD

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Yin, Lina; Zhou, Yunfeng; Liu, Guoming; Wu, Jian; Lin, Jintong

    2006-01-01

    Future network will include wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM) technologies. All-optical format conversion between their respective preferable data formats, non-return-to-zero (NRZ) and return-to-zero (RZ), may become an important technology. In this paper, 10Gbit/s all-optical NRZ-to-RZ conversion is demonstrated based on terahertz optical asymmetric demultiplexer (TOAD) using clock all-optically recovered from the NRZ signal for the first time. The clock component is enhanced in an SOA and the pseudo-return-to-zero (PRZ) signal is filtered. The PRZ signal is input into an injection mode-locked fiber ring laser for clock recovery. The recovered clock and the NRZ signal are input into TOAD as pump signal and probe signal, respectively, and format conversion is performed. The quality of the converted RZ signal is determined by that of the recovered clock and the NRZ signal, whereas hardly influenced by gain recovery time of the SOA. In the experimental demonstration, the obtained RZ signal has an extinction ratio of 8.7dB and low pattern dependency. After conversion, the spectrum broadens obviously and shows multimode structure with spectrum interval of 0.08nm, which matches with the bit rate 10Gbit/s. Furthermore, this format conversion method has some tolerance on the pattern dependency of the clock signal.

  6. [Influence and mechanism of calcium-based desulfurizer on NO conversion in fluidized bed of coal].

    PubMed

    Zhang, Dongping; Chi, Yong; Yan, Jianhua; Li, Xiangpai; Cao, Yuchun; Cen, Kefa

    2003-01-01

    On the experimental table of fluidized bed which scale was phi 150 mm x 1000 mm and temperature interval was from 840 degrees C to 960 degrees C, the influence of desulfurizer variety, particle size and molar ratios Ca/S on nitrogen conversion to NO were studied. This paper elaborated on the mechanism of calcium-based desulfurizer lead to the increase of NO conversion rate. Experiment presented that given identical quantities, burnt calcium had maximum NO conversion rate, then limestone, calcite last. Nitrogen conversion to NO increased with increasing molar ratios Ca/S. When the particle size was between 1-2 mm, the NO conversion rate was the maximum, second was 2-3 mm, the last 0.2-1 mm. HCl, HF, SO2 decreased with calcium addition. At the same time H, OH, HO2 radicals increased. The CO oxidation was favored, the reaction of monoxide and NO catalyzed by char, sand, ash will weaken, therefore NO content will increase.

  7. Image quality evaluation of direct-conversion digital mammography system with new dual a-Se layer detector

    NASA Astrophysics Data System (ADS)

    Kuwabara, Takao; Iwasaki, Nobuyuki; Sendai, Tomonari; Furue, Ryosuke; Agano, Toshitaka

    2009-02-01

    To increase the detection performance of breast cancers in mammograms, we need to improve shape delineation of micro calcifications and tumors. We accomplished this by developing a direct-conversion mammography system with an optical reading method and a new dual a-Se layer detector. The system achieved both small pixel size (50 micrometer) and a high Detective Quantum Efficiency (DQE) realized by 100 % of fill factor and noise reduction. We evaluated image quality performance and determined the best exposure conditions. We measured DQE and Modulation Transfer Function(MTF) according to the IEC62220-1-2. High DQE was maintained at a low radiation dosage, indicating that the optical reading method accompanies low noises. Response of MTF was maintained at up to the Nyquist frequency of 10 cyc/mm, which corresponds to 50 micrometer pixel size. To determine the best exposure conditions, we measured Contrast to Noise Ratio (CNR) and visually evaluated images of a resected breast under conditions of MoMo, MoRh, and WRh. There were occasional disagreements between the exposure conditions for achieving the maximum CNR and those for the best image graded by the visual evaluation. This was probably because CNR measurement does not measure effects of scattered X-ray. The images verified the improvement in detection and delineation performance of micro calcifications and tumors.

  8. Overview of condition monitoring and operation control of electric power conversion systems in direct-drive wind turbines under faults

    NASA Astrophysics Data System (ADS)

    Huang, Shoudao; Wu, Xuan; Liu, Xiao; Gao, Jian; He, Yunze

    2017-09-01

    Electric power conversion system (EPCS), which consists of a generator and power converter, is one of the most important subsystems in a direct-drive wind turbine (DD-WT). However, this component accounts for the most failures (approximately 60% of the total number) in the entire DD-WT system according to statistical data. To improve the reliability of EPCSs and reduce the operation and maintenance cost of DD-WTs, numerous researchers have studied condition monitoring (CM) and fault diagnostics (FD). Numerous CM and FD techniques, which have respective advantages and disadvantages, have emerged. This paper provides an overview of the CM, FD, and operation control of EPCSs in DD-WTs under faults. After introducing the functional principle and structure of EPCS, this survey discusses the common failures in wind generators and power converters; briefly reviewed CM and FD methods and operation control of these generators and power converters under faults; and discussed the grid voltage faults related to EPCSs in DD-WTs. These theories and their related technical concepts are systematically discussed. Finally, predicted development trends are presented. The paper provides a valuable reference for developing service quality evaluation methods and fault operation control systems to achieve high-performance and high-intelligence DD-WTs.

  9. Overview of condition monitoring and operation control of electric power conversion systems in direct-drive wind turbines under faults

    NASA Astrophysics Data System (ADS)

    Huang, Shoudao; Wu, Xuan; Liu, Xiao; Gao, Jian; He, Yunze

    2017-07-01

    Electric power conversion system (EPCS), which consists of a generator and power converter, is one of the most important subsystems in a direct-drive wind turbine (DD-WT). However, this component accounts for the most failures (approximately 60% of the total number) in the entire DD-WT system according to statistical data. To improve the reliability of EPCSs and reduce the operation and maintenance cost of DD-WTs, numerous researchers have studied condition monitoring (CM) and fault diagnostics (FD). Numerous CM and FD techniques, which have respective advantages and disadvantages, have emerged. This paper provides an overview of the CM, FD, and operation control of EPCSs in DD-WTs under faults. After introducing the functional principle and structure of EPCS, this survey discusses the common failures in wind generators and power converters; briefly reviewed CM and FD methods and operation control of these generators and power converters under faults; and discussed the grid voltage faults related to EPCSs in DD-WTs. These theories and their related technical concepts are systematically discussed. Finally, predicted development trends are presented. The paper provides a valuable reference for developing service quality evaluation methods and fault operation control systems to achieve high-performance and high-intelligence DD-WTs.

  10. Frequency domain near-infrared multiwavelength imager design using high-speed, direct analog-to-digital conversion

    PubMed Central

    Zimmermann, Bernhard B.; Fang, Qianqian; Boas, David A.; Carp, Stefan A.

    2016-01-01

    Abstract. Frequency domain near-infrared spectroscopy (FD-NIRS) has proven to be a reliable method for quantification of tissue absolute optical properties. We present a full-sampling direct analog-to-digital conversion FD-NIR imager. While we developed this instrument with a focus on high-speed optical breast tomographic imaging, the proposed design is suitable for a wide-range of biophotonic applications where fast, accurate quantification of absolute optical properties is needed. Simultaneous dual wavelength operation at 685 and 830 nm is achieved by concurrent 67.5 and 75 MHz frequency modulation of each laser source, respectively, followed by digitization using a high-speed (180  MS/s) 16-bit A/D converter and hybrid FPGA-assisted demodulation. The instrument supports 25 source locations and features 20 concurrently operating detectors. The noise floor of the instrument was measured at <1.4  pW/√Hz, and a dynamic range of 115+ dB, corresponding to nearly six orders of magnitude, has been demonstrated. Titration experiments consisting of 200 different absorption and scattering values were conducted to demonstrate accurate optical property quantification over the entire range of physiologically expected values. PMID:26813081

  11. Frequency domain near-infrared multiwavelength imager design using high-speed, direct analog-to-digital conversion

    NASA Astrophysics Data System (ADS)

    Zimmermann, Bernhard B.; Fang, Qianqian; Boas, David A.; Carp, Stefan A.

    2016-01-01

    Frequency domain near-infrared spectroscopy (FD-NIRS) has proven to be a reliable method for quantification of tissue absolute optical properties. We present a full-sampling direct analog-to-digital conversion FD-NIR imager. While we developed this instrument with a focus on high-speed optical breast tomographic imaging, the proposed design is suitable for a wide-range of biophotonic applications where fast, accurate quantification of absolute optical properties is needed. Simultaneous dual wavelength operation at 685 and 830 nm is achieved by concurrent 67.5 and 75 MHz frequency modulation of each laser source, respectively, followed by digitization using a high-speed (180 MS/s) 16-bit A/D converter and hybrid FPGA-assisted demodulation. The instrument supports 25 source locations and features 20 concurrently operating detectors. The noise floor of the instrument was measured at <1.4 pW/√Hz, and a dynamic range of 115+ dB, corresponding to nearly six orders of magnitude, has been demonstrated. Titration experiments consisting of 200 different absorption and scattering values were conducted to demonstrate accurate optical property quantification over the entire range of physiologically expected values.

  12. Direct conversion of h-BN into c-BN and formation of epitaxial c-BN/diamond heterostructures

    NASA Astrophysics Data System (ADS)

    Narayan, Jagdish; Bhaumik, Anagh; Xu, Weizong

    2016-05-01

    We have created a new state of BN (named Q-BN) through rapid melting and super undercooling and quenching by using nanosecond laser pulses. Phase pure c-BN is formed either by direct quenching of super undercooled liquid or by nucleation and growth from Q-BN. Thus, a direct conversion of hexagonal boron nitride (h-BN) into phase-pure cubic boron nitride (c-BN) is achieved by nanosecond pulsed laser melting at ambient temperatures and atmospheric pressure in air. According to the P-T phase diagram, the transformation from h-BN into c-BN under equilibrium processing can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa or 3700 K/7.0 GPa with a recent theoretical refinement. Using nonequilibrium nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to the formation of a new phase, named as Q-BN. We present detailed characterization of Q-BN and c-BN layers by using Raman spectroscopy, high-resolution scanning electron microscopy, electron-back-scatter diffraction, high-resolution TEM, and electron energy loss spectroscopy, and discuss the mechanism of formation of nanodots, nanoneedles, microneedles, and single-crystal c-BN on sapphire substrate. We have also deposited diamond by pulsed laser deposition of carbon on c-BN and created c-BN/diamond heterostructures, where c-BN acts as a template for epitaxial diamond growth. We discuss the mechanism of epitaxial c-BN and diamond growth on lattice matching c-BN template under pulsed laser evaporation of amorphous carbon, and the impact of this discovery on a variety of applications.

  13. Direct conversion of h-BN into c-BN and formation of epitaxial c-BN/diamond heterostructures

    SciTech Connect

    Narayan, Jagdish Bhaumik, Anagh; Xu, Weizong

    2016-05-14

    We have created a new state of BN (named Q-BN) through rapid melting and super undercooling and quenching by using nanosecond laser pulses. Phase pure c-BN is formed either by direct quenching of super undercooled liquid or by nucleation and growth from Q-BN. Thus, a direct conversion of hexagonal boron nitride (h-BN) into phase-pure cubic boron nitride (c-BN) is achieved by nanosecond pulsed laser melting at ambient temperatures and atmospheric pressure in air. According to the P-T phase diagram, the transformation from h-BN into c-BN under equilibrium processing can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa or 3700 K/7.0 GPa with a recent theoretical refinement. Using nonequilibrium nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to the formation of a new phase, named as Q-BN. We present detailed characterization of Q-BN and c-BN layers by using Raman spectroscopy, high-resolution scanning electron microscopy, electron-back-scatter diffraction, high-resolution TEM, and electron energy loss spectroscopy, and discuss the mechanism of formation of nanodots, nanoneedles, microneedles, and single-crystal c-BN on sapphire substrate. We have also deposited diamond by pulsed laser deposition of carbon on c-BN and created c-BN/diamond heterostructures, where c-BN acts as a template for epitaxial diamond growth. We discuss the mechanism of epitaxial c-BN and diamond growth on lattice matching c-BN template under pulsed laser evaporation of amorphous carbon, and the impact of this discovery on a variety of applications.

  14. Nonlinear frequency conversion effect in a one-dimensional graphene-based photonic crystal

    NASA Astrophysics Data System (ADS)

    Wicharn, S.; Buranasiri, P.

    2015-07-01

    In this research, the nonlinear frequency conversion effect based on four-wave mixing (FWM) principle in a onedimensional graphene-based photonics crystal (1D-GPC) has been investigated numerically. The 1D-GPC structure is composed of two periodically alternating material layers, which are graphene-silicon dioxide bilayer system and silicon membrane. Since, the third-order nonlinear susceptibility χ(3) of bilayer system is hundred time higher than pure silicon dioxide layer, so the enhancement of FWM response can be achieved inside the structure with optimizing photon energy being much higher than a chemical potential level (μ) of graphene sheet. In addition, the conversion efficiencies of 1DGPC structure are compared with chalcogenide based photonic structure for showing that 1D-GPC structure can enhance nonlinear effect by a factor of 100 above the chalcogenide based structure with the same structure length.

  15. On the conversion of infrared radiation from fission reactor-based photon engine into parallel beam

    NASA Astrophysics Data System (ADS)

    Gulevich, Andrey V.; Levchenko, Vladislav E.; Loginov, Nicolay I.; Kukharchuk, Oleg F.; Evtodiev, Denis A.; Zrodnikov, Anatoly V.

    2002-01-01

    The efficiency of infrared radiation conversion from photon engine based on fission reactor into parallel photon beam is discussed. Two different ways of doing that are considered. One of them is to use the parabolic mirror to convert of infrared radiation into parallel photon beam. The another one is based on the use of special lattice consisting of numerous light conductors. The experimental facility and some results are described. .

  16. Carbon nanotube/polymer composite coated tapered fiber for four wave mixing based wavelength conversion.

    PubMed

    Xu, Bo; Omura, Mika; Takiguchi, Masato; Martinez, Amos; Ishigure, Takaaki; Yamashita, Shinji; Kuga, Takahiro

    2013-02-11

    In this paper, we demonstrate a nonlinear optical device based on a fiber taper coated with a carbon nanotube (CNT)/polymer composite. Using this device, four wave mixing (FWM) based wavelength conversion of 10 Gb/s Non-return-to-zero signal is achieved. In addition, we investigate wavelength tuning, two photon absorption and estimate the effective nonlinear coefficient of the CNTs embedded in the tapered fiber to be 1816.8 W(-1)km(-1).

  17. Solar-thermal conversion and thermal energy storage of graphene foam-based composites

    NASA Astrophysics Data System (ADS)

    Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

    2016-07-01

    Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a

  18. Modeling plasma-based CO2 conversion: crucial role of the dissociation cross section

    NASA Astrophysics Data System (ADS)

    Bogaerts, Annemie; Wang, Weizong; Berthelot, Antonin; Guerra, Vasco

    2016-10-01

    Plasma-based CO2 conversion is gaining increasing interest worldwide. A large research effort is devoted to improving the energy efficiency. For this purpose, it is very important to understand the underlying mechanisms of the CO2 conversion. The latter can be obtained by computer modeling, describing in detail the behavior of the various plasma species and all relevant chemical processes. However, the accuracy of the modeling results critically depends on the accuracy of the assumed input data, like cross sections. This is especially true for the cross section of electron impact dissociation, as the latter process is believed to proceed through electron impact excitation, but it is not clear from the literature which excitation channels effectively lead to dissociation. Therefore, the present paper discusses the effect of different electron impact dissociation cross sections reported in the literature on the calculated CO2 conversion, for a dielectric barrier discharge (DBD) and a microwave (MW) plasma. Comparison is made to experimental data for the DBD case, to elucidate which cross section might be the most realistic. This comparison reveals that the cross sections proposed by Itikawa and by Polak and Slovetsky both seem to underestimate the CO2 conversion. The cross sections recommended by Phelps with thresholds of 7 eV and 10.5 eV yield a CO2 conversion only slightly lower than the experimental data, but the sum of both cross sections overestimates the values, indicating that these cross sections represent dissociation, but most probably also include other (pure excitation) channels. Our calculations indicate that the choice of the electron impact dissociation cross section is crucial for the DBD, where this process is the dominant mechanism for CO2 conversion. In the MW plasma, it is only significant at pressures up to 100 mbar, while it is of minor importance for higher pressures, when dissociation proceeds mainly through collisions of CO2 with heavy

  19. Graphitic design: prospects of graphene-based nanocomposites for solar energy conversion, storage, and sensing.

    PubMed

    Lightcap, Ian V; Kamat, Prashant V

    2013-10-15

    Graphene not only possesses interesting electrochemical behavior but also has a remarkable surface area and mechanical strength and is naturally abundant, all advantageous properties for the design of tailored composite materials. Graphene-semiconductor or -metal nanoparticle composites have the potential to function as efficient, multifunctional materials for energy conversion and storage. These next-generation composite systems could possess the capability to integrate conversion and storage of solar energy, detection, and selective destruction of trace environmental contaminants or achieve single-substrate, multistep heterogeneous catalysis. These advanced materials may soon become a reality, based on encouraging results in the key areas of energy conversion and sensing using graphene oxide as a support structure. Through recent advances, chemists can now integrate such processes on a single substrate while using synthetic designs that combine simplicity with a high degree of structural and composition selectivity. This progress represents the beginning of a transformative movement leveraging the advancements of single-purpose chemistry toward the creation of composites designed to address whole-process applications. The promising field of graphene nanocomposites for sensing and energy applications is based on fundamental studies that explain the electronic interactions between semiconductor or metal nanoparticles and graphene. In particular, reduced graphene oxide is a suitable composite substrate because of its two-dimensional structure, outstanding surface area, and electrical conductivity. In this Account, we describe common assembly methods for graphene composite materials and examine key studies that characterize its excited state interactions. We also discuss strategies to develop graphene composites and control electron capture and transport through the 2D carbon network. In addition, we provide a brief overview of advances in sensing, energy conversion

  20. Hierarchy of conversational rule violations involving utterance-based augmentative and alternative communication systems.

    PubMed

    Hoag, Linda A; Bedrosian, Jan L; McCoy, Kathleen F; Johnson, Dallas E

    2008-01-01

    This study examined the effects of using messages with conversational rule violations on attitudes toward people who used utterance-based augmentative and alternative communication (AAC) systems in transactional interactions. Specifically, the ratings were compared across messages with relevance, informativeness, and brevity violations, when latency remained constant (i.e., short). The 96 participating sales clerks viewed scripted, videotaped bookstore conversations and completed an attitude questionnaire. Results indicated that the prestored message with repeated words/phrases was rated the highest, followed by the message with excessive information; next was the message with inadequate information, followed by the message with partly relevant information. The findings may be useful to those using utterance-based systems when making message choices during interactions with service providers. Technological implications point to the development of schema/script-based systems and intelligent editing.

  1. Graphlet-based Characterization of Directed Networks

    NASA Astrophysics Data System (ADS)

    Sarajlić, Anida; Malod-Dognin, Noël; Yaveroğlu, Ömer Nebil; Pržulj, Nataša

    2016-10-01

    We are flooded with large-scale, dynamic, directed, networked data. Analyses requiring exact comparisons between networks are computationally intractable, so new methodologies are sought. To analyse directed networks, we extend graphlets (small induced sub-graphs) and their degrees to directed data. Using these directed graphlets, we generalise state-of-the-art network distance measures (RGF, GDDA and GCD) to directed networks and show their superiority for comparing directed networks. Also, we extend the canonical correlation analysis framework that enables uncovering the relationships between the wiring patterns around nodes in a directed network and their expert annotations. On directed World Trade Networks (WTNs), our methodology allows uncovering the core-broker-periphery structure of the WTN, predicting the economic attributes of a country, such as its gross domestic product, from its wiring patterns in the WTN for up-to ten years in the future. It does so by enabling us to track the dynamics of a country’s positioning in the WTN over years. On directed metabolic networks, our framework yields insights into preservation of enzyme function from the network wiring patterns rather than from sequence data. Overall, our methodology enables advanced analyses of directed networked data from any area of science, allowing domain-specific interpretation of a directed network’s topology.

  2. Graphlet-based Characterization of Directed Networks

    PubMed Central

    Sarajlić, Anida; Malod-Dognin, Noël; Yaveroğlu, Ömer Nebil; Pržulj, Nataša

    2016-01-01

    We are flooded with large-scale, dynamic, directed, networked data. Analyses requiring exact comparisons between networks are computationally intractable, so new methodologies are sought. To analyse directed networks, we extend graphlets (small induced sub-graphs) and their degrees to directed data. Using these directed graphlets, we generalise state-of-the-art network distance measures (RGF, GDDA and GCD) to directed networks and show their superiority for comparing directed networks. Also, we extend the canonical correlation analysis framework that enables uncovering the relationships between the wiring patterns around nodes in a directed network and their expert annotations. On directed World Trade Networks (WTNs), our methodology allows uncovering the core-broker-periphery structure of the WTN, predicting the economic attributes of a country, such as its gross domestic product, from its wiring patterns in the WTN for up-to ten years in the future. It does so by enabling us to track the dynamics of a country’s positioning in the WTN over years. On directed metabolic networks, our framework yields insights into preservation of enzyme function from the network wiring patterns rather than from sequence data. Overall, our methodology enables advanced analyses of directed networked data from any area of science, allowing domain-specific interpretation of a directed network’s topology. PMID:27734973

  3. Test plan for non-radioactive testing of vertical calciner for development of direct denitration conversion of Pu-bearing liquors to stable, storage solids

    SciTech Connect

    Fisher, F.D.

    1995-03-30

    Plutonium-bearing liquors, including ANL scrap liquors, will be used for development and demonstration of a vertical calciner direct denitration process for conversion of those liquors to stable, storable PuO{sub 2}-rich solids. This test plan is to test with non-radioactive stand-in materials to demonstrate adequate performance of the vertical calciner and ancillary equipment.

  4. Review of pyroelectric thermal energy harvesting and new MEMs-based resonant energy conversion techniques

    NASA Astrophysics Data System (ADS)

    Hunter, Scott R.; Lavrik, Nickolay V.; Mostafa, Salwa; Rajic, Slo; Datskos, Panos G.

    2012-06-01

    Harvesting electrical energy from thermal energy sources using pyroelectric conversion techniques has been under investigation for over 50 years, but it has not received the attention that thermoelectric energy harvesting techniques have during this time period. This lack of interest stems from early studies which found that the energy conversion efficiencies achievable using pyroelectric materials were several times less than those potentially achievable with thermoelectrics. More recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. This paper will review the recent history in this field and describe the techniques that are being developed to increase the opportunities for pyroelectric energy harvesting. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, are also outlined. The approach uses a resonantly driven, pyroelectric capacitive bimorph cantilever structure that can be used to rapidly cycle the temperature in the energy harvester. The device has been modeled using a finite element multi-physics based method, where the effect of the structure material properties and system parameters on the frequency and magnitude of temperature cycling, and the efficiency of energy recycling using the proposed structure, have been modeled. Results show that thermal contact conductance and heat source temperature differences play key roles in dominating the cantilever resonant frequency and efficiency of the energy conversion technique. This paper outlines the modeling, fabrication and testing of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal

  5. Review of pyroelectric thermal energy harvesting and new MEMs based resonant energy conversion techniques

    SciTech Connect

    Hunter, Scott Robert; Lavrik, Nickolay V; Mostafa, Salwa; Rajic, Slobodan; Datskos, Panos G

    2012-01-01

    Harvesting electrical energy from thermal energy sources using pyroelectric conversion techniques has been under investigation for over 50 years, but it has not received the attention that thermoelectric energy harvesting techniques have during this time period. This lack of interest stems from early studies which found that the energy conversion efficiencies achievable using pyroelectric materials were several times less than those potentially achievable with thermoelectrics. More recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. This paper will review the recent history in this field and describe the techniques that are being developed to increase the opportunities for pyroelectric energy harvesting. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, are also outlined. The approach uses a resonantly driven, pyroelectric capacitive bimorph cantilever structure that can be used to rapidly cycle the temperature in the energy harvester. The device has been modeled using a finite element multi-physics based method, where the effect of the structure material properties and system parameters on the frequency and magnitude of temperature cycling, and the efficiency of energy recycling using the proposed structure, have been modeled. Results show that thermal contact conductance and heat source temperature differences play key roles in dominating the cantilever resonant frequency and efficiency of the energy conversion technique. This paper outlines the modeling, fabrication and testing of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal

  6. Direct thermal to electrical energy conversion using 9.5/65/35 PLZT ceramics in the ergodic relaxor phase.

    PubMed

    Chin, Thomas K; Lee, Felix Y; McKinley, Ian M; Goljahi, Sam; Lynch, Christopher S; Pilon, Laurent

    2012-11-01

    This paper reports on direct thermal to electrical energy conversion by performing the Olsen cycle on 9.5/65/35 lead lanthanum zirconate titanate (PLZT). The Olsen cycle consists of two isothermal and two isoelectric field processes in the electric displacement versus electric field diagram. It was performed by alternatively dipping the material in hot and cold dielectric fluid baths under specified electric fields. The effects of applied electric field, sample thickness, electrode material, operating temperature, and cycle frequency on the energy and power densities were investigated. A maximum energy density of 637 ± 20 J/L/cycle was achieved at 0.054 Hz with a 250-μm-thick sample featuring Pt electrodes and coated with a silicone conformal coating. The operating temperatures varied between 3°C and 140°C and the electric field was cycled between 0.2 and 6.0 MV/m. A maximum power density of 55 ± 8 W/L was obtained at 0.125 Hz under the same operating temperatures and electric fields. The dielectric strength of the material, and therefore the energy and power densities generated, increased when the sample thickness decreased from 500 to 250 μm. Furthermore, the electrode material was found to have no significant effect on the energy and power densities for samples subject to the same operating temperatures and electric fields. However, samples with electrode material possessing thermal expansion coefficients similar to that of PLZT were capable of withstanding larger temperature swings. Finally, a fatigue test showed that the power generation gradually degraded when the sample was subject to repeated thermoelectrical loading.

  7. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 3, April 16--July 15, 1987

    SciTech Connect

    Wilson, R.B. Jr.; Chan, Yee Wai

    1987-08-28

    The goal of this research is to develop catalysts that directly convert methane and light hydrocarbons to intermediates that can, as economics dictate, be subsequently converted either to liquid fuels or value-added chemicals. In this program we are exploring two approaches to developing such catalysts. The first approach consists of developing advanced catalysts for reforming methane. We will prepare the catalysts by reacting organometallic complexes of transition metals (Fe, Ru, Rh, and Re) with zeolitic and rare-earth-exchanged zeolitic supports to produce surface-confined metal complexes in the zeolite pores. Our second approach entails synthesizing the porphyrin and phthalocyanine complexes of Cr, Mn, Ru, Fe, and/or Co within the pores of zeolitic supports for use as selective oxidation catalysts for methane and light hydrocarbons. During this reporting period, we concentrated on synthesizing and testing methane oxidation catalysts using the automated GC sampling system. We modified our preparation method of zeolite-encapsulated phthalocyanines (PC). The catalysts have higher complex loading, and the uncomplexed metal ions were back-exchanged by sodium ions (to remove any uncomplexed metal ions). Four metal ions were used: cobalt, iron, ruthenium, and manganese. We also synthesized four zeolite-encapsulated tetraphenylporphyrin (TPP) complexes using the same metals. These catalysts were tested for methane oxidation in the temperature range from 300{degrees} to 500{degrees}C at 50 psig pressure. The RUPC, COTPP, and MNTPP showed activity toward the formation of methanol. The RUPC zeolite gave the best methanol yield. The methane conversion was 4.8%, and the selectivity to methanol is 11.3% at 375{degrees}C. Again, the major products are carbon dioxide and water in every catalyst we tested during this reporting period.

  8. Direct catalytic conversion of methane and light hydrocarbon gases. Final report, October 1, 1986--July 31, 1989

    SciTech Connect

    Wilson, R.B. Jr.; Posin, B.M.; Chan, Yee-Wai

    1995-06-01

    This project explored conversion of methane to useful products by two techniques that do not involve oxidative coupling. The first approach was direct catalytic dehydrocoupling of methane to give hydrocarbons and hydrogen. The second approach was oxidation of methane to methanol by using heterogenized versions of catalysts that were developed as homogeneous models of cytochrome-P450, an enzyme that actively hydroxylates hydrocarbons by using molecular oxygen. Two possibilities exist for dehydrocoupling of methane to higher hydrocarbons: The first, oxidative coupling to ethane/ethylene and water, is the subject of intense current interest. Nonoxidative coupling to higher hydrocarbons and hydrogen is endothermic, but in the absence of coke formation the theoretical thermodynamic equilibrium yield of hydrocarbons varies from 25% at 827{degrees}C to 65% at 1100{degrees}C (at atmospheric pressure). In this project we synthesized novel, highly dispersed metal catalysts by attaching metal clusters to inorganic supports. The second approach mimics microbial metabolism of methane to produce methanol. The methane mono-oxygenase enzyme responsible for the oxidation of methane to methanol in biological systems has exceptional selectivity and very good rates. Enzyme mimics are systems that function as the enzymes do but overcome the problems of slow rates and poor stability. Most of that effort has focused on mimics of cytochrome P-450, which is a very active selective oxidation enzyme and has a metalloporphyrin at the active site. The interest in nonporphyrin mimics coincides with the interest in methane mono-oxygenase, whose active site has been identified as a {mu}-oxo dinuclear iron complex.We employed mimics of cytochrome P-450, heterogenized to provide additional stability. The oxidation of methane with molecular oxygen was investigated in a fixed-bed, down-flow reactor with various anchored metal phthalocyanines (PC) and porphyrins (TPP) as the catalysts.

  9. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 7, April 16, 1988--July 15, 1988

    SciTech Connect

    Wilson, R.B. Jr.; Chan, Yee Wai; Posin, B.M.

    1988-08-31

    The goal of this research is to develop catalysts that directly convert methane and light hydrocarbons to intermediates that later can be converted to either liquid fuels or value-added chemicals, as economics dictate. During this reporting period, much of our effort focused on investigating the stability of the methane reforming catalysts (Task 2) with respect to storage time. Many of these catalysts demonstrated lessened activity when they were reexamined up to 18 months after they ere first synthesized and tested. We also synthesized and tested two new phthalocyanines supported on magnesia (MgO) for examination in the methane oxidation reaction. We reexamined many of the hexaruthenium and tetraruthenium clusters which had been supported on zeolite Y, zeolite 5A, alumina or magnesia. These reexaminations were conducted at relatively slow flow rates (15 ml/min), since previous studies had shown that the lower flow rates maximized the conversion of methane in this reaction. In every case, the catalyst exhibited diminished activity compared to the earlier runs. In addition, the selectivity of the catalysts changed as well; relatively less C{sub 2} and no C{sub 6} was observed in the reactions conducted during this reporting period. In the previous technical report we reported that palladium tetrasulfophthalocyanine (PDTSPC) supported on MgO exhibited exceptional activity in the methane oxidation reaction; it produced ethane at much lower temperatures than previously reported in the literature. We synthesized two close analogues of this compound, one with a different metal (nickel) from the same family as palladium, and the other with a different substituent (carboxylic acid rather than sulfonic acid) on the phthalocyanine ring. Both of these complexes were supported on magnesia, and tested for activity. The nickel complex displayed some activity, producing only carbon dioxide and water.

  10. Microwave birefringent metamaterials for polarization conversion based on spoof surface plasmon polariton modes.

    PubMed

    Li, Yongfeng; Zhang, Jieqiu; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Feng, Dayi; Xu, Zhuo; Qu, Shaobo

    2016-10-04

    We propose the design of wideband birefringent metamaterials based on spoof surface plasmon polaritons (SSPPs). Spatial k-dispersion design of SSPP modes in metamaterials is adopted to achieve high-efficiency transmission of electromagnetic waves through the metamaterial layer. By anisotropic design, the transmission phase accumulation in metamaterials can be independently modulated for x- and y-polarized components of incident waves. Since the dispersion curve of SSPPs is nonlinear, frequency-dependent phase differences can be obtained between the two orthogonal components of transmitted waves. As an example, we demonstrate a microwave birefringent metamaterials composed of fishbone structures. The full-polarization-state conversions on the zero-longitude line of Poincaré sphere can be fulfilled twice in 6-20 GHz for both linearly polarized (LP) and circularly polarized (CP) waves incidence. Besides, at a given frequency, the full-polarization-state conversion can be achieved by changing the polarization angle of the incident LP waves. Both the simulation and experiment results verify the high-efficiency polarization conversion functions of the birefringent metamaterial, including circular-to-circular, circular-to-linear(linear-to-circular), linear-to-linear polarization conversions.

  11. Solar-thermal conversion and thermal energy storage of graphene foam-based composites.

    PubMed

    Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

    2016-08-14

    Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

  12. Thermoelectric-Generator-Based DC-DC Conversion Networks for Automotive Applications

    NASA Astrophysics Data System (ADS)

    Li, Molan; Xu, Shaohui; Chen, Qiang; Zheng, Li-Rong

    2011-05-01

    Maximizing electrical energy generation through waste heat recovery is one of the modern research questions within automotive applications of thermoelectric (TE) technologies. This paper proposes a novel concept of distributed multisection multilevel DC-DC conversion networks based on thermoelectric generators (TEGs) for automotive applications. The concept incorporates a bottom-up design approach to collect, convert, and manage vehicle waste heat efficiently. Several state-of-the-art thermoelectric materials are analyzed for the purpose of power generation at each waste heat harvesting location on a vehicle. Optimal materials and TE couple configurations are suggested. Moreover, a comparison of prevailing DC-DC conversion techniques was made with respect to applications at each conversion level within the network. Furthermore, higher-level design considerations are discussed according to system specifications. Finally, a case study is performed to compare the performance of the proposed network and a traditional single-stage system. The results show that the proposed network enhances the system conversion efficiency by up to 400%.

  13. Microwave birefringent metamaterials for polarization conversion based on spoof surface plasmon polariton modes

    PubMed Central

    Li, Yongfeng; Zhang, Jieqiu; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Feng, Dayi; Xu, Zhuo; Qu, Shaobo

    2016-01-01

    We propose the design of wideband birefringent metamaterials based on spoof surface plasmon polaritons (SSPPs). Spatial k-dispersion design of SSPP modes in metamaterials is adopted to achieve high-efficiency transmission of electromagnetic waves through the metamaterial layer. By anisotropic design, the transmission phase accumulation in metamaterials can be independently modulated for x- and y-polarized components of incident waves. Since the dispersion curve of SSPPs is nonlinear, frequency-dependent phase differences can be obtained between the two orthogonal components of transmitted waves. As an example, we demonstrate a microwave birefringent metamaterials composed of fishbone structures. The full-polarization-state conversions on the zero-longitude line of Poincaré sphere can be fulfilled twice in 6–20 GHz for both linearly polarized (LP) and circularly polarized (CP) waves incidence. Besides, at a given frequency, the full-polarization-state conversion can be achieved by changing the polarization angle of the incident LP waves. Both the simulation and experiment results verify the high-efficiency polarization conversion functions of the birefringent metamaterial, including circular-to-circular, circular-to-linear(linear-to-circular), linear-to-linear polarization conversions. PMID:27698443

  14. Microwave birefringent metamaterials for polarization conversion based on spoof surface plasmon polariton modes

    NASA Astrophysics Data System (ADS)

    Li, Yongfeng; Zhang, Jieqiu; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Feng, Dayi; Xu, Zhuo; Qu, Shaobo

    2016-10-01

    We propose the design of wideband birefringent metamaterials based on spoof surface plasmon polaritons (SSPPs). Spatial k-dispersion design of SSPP modes in metamaterials is adopted to achieve high-efficiency transmission of electromagnetic waves through the metamaterial layer. By anisotropic design, the transmission phase accumulation in metamaterials can be independently modulated for x- and y-polarized components of incident waves. Since the dispersion curve of SSPPs is nonlinear, frequency-dependent phase differences can be obtained between the two orthogonal components of transmitted waves. As an example, we demonstrate a microwave birefringent metamaterials composed of fishbone structures. The full-polarization-state conversions on the zero-longitude line of Poincaré sphere can be fulfilled twice in 6-20 GHz for both linearly polarized (LP) and circularly polarized (CP) waves incidence. Besides, at a given frequency, the full-polarization-state conversion can be achieved by changing the polarization angle of the incident LP waves. Both the simulation and experiment results verify the high-efficiency polarization conversion functions of the birefringent metamaterial, including circular-to-circular, circular-to-linear(linear-to-circular), linear-to-linear polarization conversions.

  15. Ionization based multi-directional flow sensor

    DOEpatents

    Chorpening, Benjamin T.; Casleton, Kent H.

    2009-04-28

    A method, system, and apparatus for conducting real-time monitoring of flow (airflow for example) in a system (a hybrid power generation system for example) is disclosed. The method, system and apparatus measure at least flow direction and velocity with minimal pressure drop and fast response. The apparatus comprises an ion source and a multi-directional collection device proximate the ion source. The ion source is configured to generate charged species (electrons and ions for example). The multi-directional collection source is configured to determine the direction and velocity of the flow in real-time.

  16. The Role of Conversation Policy in Carrying Out Agent Conversations

    SciTech Connect

    Link, Hamilton E.; Phillips, Laurence R.

    1999-05-20

    Structured conversation diagrams, or conversation specifications, allow agents to have predictable interactions and achieve predefined information-based goals, but they lack the flexibility needed to function robustly in an unpredictable environment. We propose a mechanism that combines a typical conversation structure with a separately established policy to generate an actual conversation. The word "policy" connotes a high-level direction external to a specific planned interaction with the environment. Policies, which describe acceptable procedures and influence decisions, can be applied to broad sets of activity. Based on their observation of issues related to a policy, agents may dynamically adjust their communication patterns. The policy object describes limitations, constraints, and requirements that may affect the conversation in certain circumstances. Using this new mechanism of interaction simplifies the description of individual conversations and allows domain-specific issues to be brought to bear more easily during agent communication. By following the behavior of the conversation specification when possible and deferring to the policy to derive behavior in exceptional circumstances, an agent is able to function predictably under normal situations and still act rationally in abnormal situations. Different conversation policies applied to a given conversation specification can change the nature of the interaction without changing the specification.

  17. Conversion Reaction-Based Oxide Nanomaterials for Lithium Ion Battery Anodes.

    PubMed

    Yu, Seung-Ho; Lee, Soo Hong; Lee, Dong Jun; Sung, Yung-Eun; Hyeon, Taeghwan

    2016-04-27

    Developing high-energy-density electrodes for lithium ion batteries (LIBs) is of primary importance to meet the challenges in electronics and automobile industries in the near future. Conversion reaction-based transition metal oxides are attractive candidates for LIB anodes because of their high theoretical capacities. This review summarizes recent advances on the development of nanostructured transition metal oxides for use in lithium ion battery anodes based on conversion reactions. The oxide materials covered in this review include oxides of iron, manganese, cobalt, copper, nickel, molybdenum, zinc, ruthenium, chromium, and tungsten, and mixed metal oxides. Various kinds of nanostructured materials including nanowires, nanosheets, hollow structures, porous structures, and oxide/carbon nanocomposites are discussed in terms of their LIB anode applications.

  18. A browser-based tool for conversion between Fortran NAMELIST and XML/HTML

    NASA Astrophysics Data System (ADS)

    Naito, O.

    A browser-based tool for conversion between Fortran NAMELIST and XML/HTML is presented. It runs on an HTML5 compliant browser and generates reusable XML files to aid interoperability. It also provides a graphical interface for editing and annotating variables in NAMELIST, hence serves as a primitive code documentation environment. Although the tool is not comprehensive, it could be viewed as a test bed for integrating legacy codes into modern systems.

  19. FWM-based wavelength conversion of 40 Gbaud PSK signals in a silicon germanium waveguide.

    PubMed

    Ettabib, Mohamed A; Hammani, Kamal; Parmigiani, Francesca; Jones, Liam; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris; Brun, Mickael; Labeye, Pierre; Nicoletti, Sergio; Petropoulos, Periklis

    2013-07-15

    We demonstrate four wave mixing (FWM) based wavelength conversion of 40 Gbaud differential phase shift keyed (DPSK) and quadrature phase shift keyed (QPSK) signals in a 2.5 cm long silicon germanium waveguide. For a 290 mW pump power, bit error ratio (BER) measurements show approximately a 2-dB power penalty in both cases of DPSK (measured at a BER of 10(-9)) and QPSK (at a BER of 10(-3)) signals that we examined.

  20. Synthesis of ceramic-based porous gradient structures for applications in energy conversion and related fields

    NASA Astrophysics Data System (ADS)

    Graule, Thomas; Ozog, Paulina; Durif, Caroline; Wilkens-Heinecke, Judit; Kata, Dariusz

    2016-06-01

    Porous, graded ceramic structures are of high relevance in the field of energy conversion as well as in catalysis, and additionally in filtration technology and in biomedical applications. Among different technologies for the tailored design for such structures we demonstrate here a new environmental friendly UV curing-based concept to prepare laminated structures with pore sizes ranging from a few microns up to 50 microns in diameter and with porosities ranging from 10% up to 75 vol.% porosity.

  1. MO-E-17A-12: Direct Realization of the CT Dose to Phantom: Energy to Heat Conversion in Polyethylene Using Calorimetry

    SciTech Connect

    Chen-Mayer, H; Tosh, R

    2014-06-15

    Purpose: To develop a primary reference standard for absorbed dose to phantom for medical CT dosimetry. CT dosimetry relies on the implementation of the CTDI standard based on air kerma. We are taking a step toward an absorbed dose to water standard by first investigating the dose in a solid phantom. By directly measuring the heat converted from the incident radiation, the absorbed dose in the phantom at a point can be assessed with primary methods without relying on indirect conversions. Methods: The calorimeter contains two small thermistors embedded in a removable PE “core” inserted into the cylindrical HDPE phantom. A core made with polystyrene (PS) was also tested because of its purportedly negligible heat defect. Measurements were made using the two cores and with a calibrated ionization chamber in a CT beam. The air chamber values were converted to the dose to medium using appropriate stopping-power ratios from the literature, and then compared to the thermal data. Results: The PS core data yielded a dose of 1.3 times (4-run average, 3% std. dev.) higher than the converted chamber value, whereas the PE core data were inexplicably higher. The possible systematic errors include 1) excess heat from the thermistors, 2) in PE the exothermic chemical reactions, 3) uncertainties of the specific heat capacities of the materials, 4) thermal drift, and 5) theoretical conversion of chamber values. Monte Carlo simulations and finite element heat transfer calculations were performed to address some of these issues. The general validity was assessed in a 6 MV photon beam with an entirely different calibration scheme. Conclusion: This study demonstrates the feasibility but also revealed the difficulty in developing a new primary reference standard for absorbed dose to material for CT. Additional experimental and theoretical work is planned to achieve our goal.

  2. Machine learning framework for early MRI-based Alzheimer's conversion prediction in MCI subjects.

    PubMed

    Moradi, Elaheh; Pepe, Antonietta; Gaser, Christian; Huttunen, Heikki; Tohka, Jussi

    2015-01-01

    Mild cognitive impairment (MCI) is a transitional stage between age-related cognitive decline and Alzheimer's disease (AD). For the effective treatment of AD, it would be important to identify MCI patients at high risk for conversion to AD. In this study, we present a novel magnetic resonance imaging (MRI)-based method for predicting the MCI-to-AD conversion from one to three years before the clinical diagnosis. First, we developed a novel MRI biomarker of MCI-to-AD conversion using semi-supervised learning and then integrated it with age and cognitive measures about the subjects using a supervised learning algorithm resulting in what we call the aggregate biomarker. The novel characteristics of the methods for learning the biomarkers are as follows: 1) We used a semi-supervised learning method (low density separation) for the construction of MRI biomarker as opposed to more typical supervised methods; 2) We performed a feature selection on MRI data from AD subjects and normal controls without using data from MCI subjects via regularized logistic regression; 3) We removed the aging effects from the MRI data before the classifier training to prevent possible confounding between AD and age related atrophies; and 4) We constructed the aggregate biomarker by first learning a separate MRI biomarker and then combining it with age and cognitive measures about the MCI subjects at the baseline by applying a random forest classifier. We experimentally demonstrated the added value of these novel characteristics in predicting the MCI-to-AD conversion on data obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. With the ADNI data, the MRI biomarker achieved a 10-fold cross-validated area under the receiver operating characteristic curve (AUC) of 0.7661 in discriminating progressive MCI patients (pMCI) from stable MCI patients (sMCI). Our aggregate biomarker based on MRI data together with baseline cognitive measurements and age achieved a 10-fold cross

  3. Directional output distance functions: endogenous directions based on exogenous normalization constraints

    USDA-ARS?s Scientific Manuscript database

    In this paper we develop a model for computing directional output distance functions with endogenously determined direction vectors. We show how this model is related to the slacks-based directional distance function introduced by Fare and Grosskopf and show how to use the slacks-based function to e...

  4. Biomass thermochemical conversion program: 1987 annual report

    SciTech Connect

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1988-01-01

    The objective of the Biomass Thermochemical Conversion Program is to generate a base of scientific data and conversion process information that will lead to establishment of cost-effective processes for conversion of biomass resources into clean fuels. To accomplish this objective, in fiscal year 1987 the Thermochemical Conversion Program sponsored research activities in the following four areas: Liquid Hydrocarbon Fuels Technology; Gasification Technology; Direct Combustion Technology; Program Support Activities. In this report an overview of the Thermochemical Conversion Program is presented. Specific research projects are then described. Major accomplishments for 1987 are summarized.

  5. Simultaneous MMW generation and up-conversion for WDM-ROF systems based on FP laser

    NASA Astrophysics Data System (ADS)

    Zhang, Chan; Ning, TiGang; Li, Jing; Li, Chao; He, Xueqing; Pei, Li

    2016-10-01

    A new wavelength division multiplexing radio-over-fiber (WDM-ROF) scheme based on Fabry-Perot (FP) laser is proposed and demonstrated for simultaneous millimeter-wave (MMW) generation and up-conversion. The tunable optical comb generated by FP laser is served as a cost-effective WDM optical source in central station (CS) and it makes all-optical up-conversion process for all channels simple compared with using a DFB array. All modes from the FP laser are modulated simultaneously by a LiNbO3 Mach-Zehnder modulator (LN-MZM) then. We have systematically compared the performances of MMW generation and up-conversion using LN-MZM based on different modulation schemes. A reflective semiconductor optical amplifiers (RSOA) is used both for the downstream modulation of each channel and for the reduction of mode partition noise (MPN) induced from FP laser. In the scheme, the multiple optical carrier suppression (OCS) modulation shows the highest receiver sensitivity and smallest power penalty over long-distance delivery. In the numerical simulation, 7 WDM channels each carrying 2.5 Gb/s baseband signal have been up-converted to 60 GHz simultaneously with good performance over 25 km single mode fiber (SMF) transmission.

  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. Conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage

    NASA Astrophysics Data System (ADS)

    Kano, Shinya; Fujii, Minoru

    2017-03-01

    We study the conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage. Heat leakage current from a hot electrode to a cold electrode is taken into account in the analysis of the harvester operation. Modeling of electrical output indicates that a maximum heat leakage current is not negligible because it is larger than that of the heat current harvested into electrical power. A reduction of heat leakage is required in this energy harvester in order to obtain efficient heat-to-electrical conversion. Multiple energy levels of a quantum dot can increase the output power of the harvester. Heavily doped colloidal semiconductor quantum dots are a possible candidate for a quantum-dot monolayer in the energy harvester to reduce heat leakage, scaling down device size, and increasing electrical output via multiple discrete energy levels.

  8. Engineering of Carbon-Based Electrocatalysts for Emerging Energy Conversion: From Fundamentality to Functionality.

    PubMed

    Zheng, Yao; Jiao, Yan; Qiao, Shi Zhang

    2015-09-23

    Over the past decade, developing advanced catalysts for clean and sustainable energy conversion has been subject to extensive study. Driven by great advances achieved in computational quantum chemistry, synthetic chemistry, and material characterization techniques, the preferential design of a most-appropriate catalyst for a specific electrochemical reaction is possible. Here a universal process for the design of high-performance carbon-based electrocatalysts, by engineering their intrinsic electronic structures and physical structures to promote their extrinsic activities for different energy conversion reactions, is presented and summarized. How such a powerful strategy may aid the discovery of more electrocatalysts for a sustainable and clean energy infrastructure is discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage.

    PubMed

    Kano, Shinya; Fujii, Minoru

    2017-03-03

    We study the conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage. Heat leakage current from a hot electrode to a cold electrode is taken into account in the analysis of the harvester operation. Modeling of electrical output indicates that a maximum heat leakage current is not negligible because it is larger than that of the heat current harvested into electrical power. A reduction of heat leakage is required in this energy harvester in order to obtain efficient heat-to-electrical conversion. Multiple energy levels of a quantum dot can increase the output power of the harvester. Heavily doped colloidal semiconductor quantum dots are a possible candidate for a quantum-dot monolayer in the energy harvester to reduce heat leakage, scaling down device size, and increasing electrical output via multiple discrete energy levels.

  10. Comprehensive characterisation of sewage sludge for thermochemical conversion processes - Based on Singapore survey.

    PubMed

    Chan, Wei Ping; Wang, Jing-Yuan

    2016-08-01

    Recently, sludge attracted great interest as a potential feedstock in thermochemical conversion processes. However, compositions and thermal degradation behaviours of sludge were highly complex and distinctive compared to other traditional feedstock led to a need of fundamental research on sludge. Comprehensive characterisation of sludge specifically for thermochemical conversion was carried out for all existing Water Reclamation Plants in Singapore. In total, 14 sludge samples collected based on the type, plant, and batch categorisation. Existing characterisation methods for physical and chemical properties were analysed and reviewed using the collected samples. Qualitative similarities and quantitative variations of different sludge samples were identified and discussed. Oxidation of inorganic in sludge during ash forming analysis found to be causing significant deviations on proximate and ultimate analysis. Therefore, alternative parameters and comparison basis including Fixed Residues (FR), Inorganic Matters (IM) and Total Inorganics (TI) were proposed for better understanding on the thermochemical characteristics of sludge. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Improved conversion efficiency of GaN-based solar cells with Mn-doped absorption layer

    NASA Astrophysics Data System (ADS)

    Sheu, Jinn-Kong; Huang, Feng-Wen; Lee, Chia-Hui; Lee, Ming-Lun; Yeh, Yu-Hsiang; Chen, Po-Cheng; Lai, Wei-Chih

    2013-08-01

    GaN-based solar cells with Mn-doped absorption layer grown by metal-organic vapor-phase epitaxy were investigated. The transmittance spectrum and the spectral response showed the presence of an Mn-related band absorption property. Power-dependent, dual-light excitation, and lock-in amplifier techniques were performed to confirm if the two-photon absorption process occurred in the solar cells with Mn-doped GaN absorption layer. Although a slight decrease in an open circuit voltage was observed, a prominent increase in the short circuit current density resulted in a significant enhancement of the overall conversion efficiency. Under one-sun air mass 1.5 G standard testing condition, the conversion efficiency of Mn-doped solar cells can be enhanced by a magnitude of 5 times compared with the cells without Mn-doped absorption layer.

  12. A universal electromagnetic energy conversion adapter based on a metamaterial absorber.

    PubMed

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D; Simons, Rainee N; Chen, Yunpeng; Xiao, John Q

    2014-09-09

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor.

  13. A universal electromagnetic energy conversion adapter based on a metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D.; Simons, Rainee N.; Chen, Yunpeng; Xiao, John Q.

    2014-09-01

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor.

  14. A universal electromagnetic energy conversion adapter based on a metamaterial absorber

    PubMed Central

    Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D.; Simons, Rainee N.; Chen, Yunpeng; Xiao, John Q.

    2014-01-01

    On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor. PMID:25200005

  15. Monte Carlo calculation of conversion coefficients for dose estimation in mammography based on a 3D detailed breast model.

    PubMed

    Wang, Wenjing; Qiu, Rui; Ren, Li; Liu, Huan; Wu, Zhen; Li, Chunyan; Niu, Yantao; Li, Junli

    2017-06-01

    based on the Chinese female breast parameters. It was used to calculate glandular tissue dose conversion coefficients for mammography. Although the accuracy of the proposed model could not be directly assessed, the consistency of the obtained results with previously performed analyses increases the confidence in the applicability of the proposed model. The proposed model could be used in dose estimation and dose optimization for mammography of Chinese women. © 2017 American Association of Physicists in Medicine.

  16. 5 CFR 315.713 - Conversion based on service in a Pathways Program under part 362 of this chapter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS CAREER AND CAREER-CONDITIONAL EMPLOYMENT Conversion to Career or Career-Conditional Employment From Other Types of Employment § 315.713 Conversion based on service... a career or career-conditional employment in the competitive service, without further competition...

  17. 5 CFR 315.713 - Conversion based on service in a Pathways Program under part 362 of this chapter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS CAREER AND CAREER-CONDITIONAL EMPLOYMENT Conversion to Career or Career-Conditional Employment From Other Types of Employment § 315.713 Conversion based on service... a career or career-conditional employment in the competitive service, without further competition...

  18. Research on Comprehensive Evaluation of Knowledge Capital of Power Enterprise Based on Membership Conversion

    NASA Astrophysics Data System (ADS)

    Ligen, Yao; Miaomiao, Li

    Based on the knowledge capital theory, the article attempts to conduct a research on the evaluation of the electric power enterprise's knowledge capital. Firstly this paper explained the theory of knowledge capital, and analyzed the particularity of the power enterprise. Then we constructed an evaluation index system on the basis of structure of knowledge capital and also established a fuzzy comprehensive evaluation model based on membership conversion. The case presented proves that this model is feasible and simple and the result of appraisal is practical and reliable.

  19. Graphene-based Electrochemical Energy Conversion and Storage: Fuel cells, Supercapacitors and Lithium Ion Batteries

    SciTech Connect

    Hou, Junbo; Shao, Yuyan; Ellis, Michael A.; Moore, Robert; Yi, Baolian

    2011-09-14

    Graphene has attracted extensive research interest due to its strictly 2-dimensional (2D) structure, which results in its unique electronic, thermal, mechanical, and chemical properties and potential technical applications. These remarkable characteristics of graphene, along with the inherent benefits of a carbon material, make it a promising candidate for application in electrochemical energy devices. This article reviews the methods of graphene preparation, introduces the unique electrochemical behavior of graphene, and summarizes the recent research and development on graphene-based fuel cells, supercapacitors and lithium ion batteries. In addition, promising areas are identified for the future development of graphene-based materials in electrochemical energy conversion and storage systems.

  20. Graphene-based electrochemical energy conversion and storage: fuel cells, supercapacitors and lithium ion batteries.

    PubMed

    Hou, Junbo; Shao, Yuyan; Ellis, Michael W; Moore, Robert B; Yi, Baolian

    2011-09-14

    Graphene has attracted extensive research interest due to its strictly 2-dimensional (2D) structure, which results in its unique electronic, thermal, mechanical, and chemical properties and potential technical applications. These remarkable characteristics of graphene, along with the inherent benefits of a carbon material, make it a promising candidate for application in electrochemical energy devices. This article reviews the methods of graphene preparation, introduces the unique electrochemical behavior of graphene, and summarizes the recent research and development on graphene-based fuel cells, supercapacitors and lithium ion batteries. In addition, promising areas are identified for the future development of graphene-based materials in electrochemical energy conversion and storage systems.

  1. Gene array analysis of neural crest cells identifies transcription factors necessary for direct conversion of embryonic fibroblasts into neural crest cells

    PubMed Central

    Motohashi, Tsutomu; Watanabe, Natsuki; Nishioka, Masahiro; Nakatake, Yuhki; Yulan, Piao; Mochizuki, Hiromi; Kawamura, Yoshifumi; Ko, Minoru S. H.; Goshima, Naoki; Kunisada, Takahiro

    2016-01-01

    ABSTRACT Neural crest cells (NC cells) are multipotent cells that emerge from the edge of the neural folds and migrate throughout the developing embryo. Although the gene regulatory network for generation of NC cells has been elucidated in detail, it has not been revealed which of the factors in the network are pivotal to directing NC identity. In this study we analyzed the gene expression profile of a pure NC subpopulation isolated from Sox10-IRES-Venus mice and investigated whether these genes played a key role in the direct conversion of Sox10-IRES-Venus mouse embryonic fibroblasts (MEFs) into NC cells. The comparative molecular profiles of NC cells and neural tube cells in 9.5-day embryos revealed genes including transcription factors selectively expressed in developing trunk NC cells. Among 25 NC cell-specific transcription factor genes tested, SOX10 and SOX9 were capable of converting MEFs into SOX10-positive (SOX10+) cells. The SOX10+ cells were then shown to differentiate into neurons, glial cells, smooth muscle cells, adipocytes and osteoblasts. These SOX10+ cells also showed limited self-renewal ability, suggesting that SOX10 and SOX9 directly converted MEFs into NC cells. Conversely, the remaining transcription factors, including well-known NC cell specifiers, were unable to convert MEFs into SOX10+ NC cells. These results suggest that SOX10 and SOX9 are the key factors necessary for the direct conversion of MEFs into NC cells. PMID:26873953

  2. Effects of direct-fed Bacillus pumilus 8G-134 on feed intake, milk yield, milk composition, feed conversion, and health condition of pre- and postpartum Holstein cows.

    PubMed

    Luan, S; Duersteler, M; Galbraith, E A; Cardoso, F C

    2015-09-01

    The usage of direct-fed microbials (DFM) has become common in the dairy industry, but questions regarding choice of strain, mode of action, and efficacy remain prevalent. The objective of this study was to evaluate the effects of a DFM (Bacillus pumilus 8G-134) on pre- and postpartum performance and incidence of subclinical ketosis in early lactation. Forty-three multiparous Holstein cows were assigned to 2 treatments in a randomized complete block design; cows in the direct-fed microbial treatment (DFMt, n=21) received 5.0×10(9) cfu/cow of B. pumilus in 28 g of a maltodextrin carrier, whereas cows in the control treatment (CON, n=22) received 28 g of maltodextrin carrier alone. Treatments were top-dressed on the total mixed ration daily. Treatments were applied from 21 d before expected calving date to 154 d after calving. Cows on treatment DFMt tended to have lower serum haptoglobin concentration than CON cows on d 14. Cows on treatment DFMt had higher IgA concentrations in milk than CON cows during the first week after calving. Cows fed DFMt had higher yields of milk, fat-corrected milk, energy-corrected milk, milk fat, and milk protein during the second week of lactation than CON; however, we found no differences between treatments on milk yield and milk components overall. Cows on DFMt tended to have higher feed conversion and to have lower prevalence of subclinical ketosis (beta-hydroxybutyrate >1.2 mmol/L) on d 5 than cows fed CON. Dry matter intake, body weight, and body condition score were not affected by DFMt supplementation. Milk production efficiencies (calculated based on fat-corrected milk and energy-corrected milk) were higher by 0.1 kg of milk per kilogram of dry matter intake in cows that received DFMt compared with cows that received CON. In conclusion, cows receiving DFMt tended to have lower incidence of subclinical ketosis than cows receiving CON. Cows fed DFMt tended to have higher feed conversion and evidence for greater immunity than CON

  3. Comparison of the Degree of Conversion of Resin Based Endodontic Sealers Using the DSC Technique

    PubMed Central

    Cotti, Elisabetta; Scungio, Paola; Dettori, Claudia; Ennas, Guido

    2011-01-01

    Objectives: The aim of this study was to determine the degree of conversion (DC) of three resin based endodontic sealers using the DSC technique. Methods: The sealers tested were: EndoREZ (ER) (Ultradent, South Jordan, UT); EndoREZ with Accelerator (ER+A) (Ultradent, South Jordan, UT); RealSeal (RS) (SybronEndo, Orange, CA). Two LED units were used to activate the sealers: UltraLume LED 5 (Ultradent, South Jordan, UT, USA); Mini LED Satelec (Satelec Acteon Group, Mérignac Cedex, France). Samples of 4.0 mg were analyzed with a DSC 7 calorimeter (Perkin Elmer Inc., Wellesley, MA, US). Each specimen was irradiated by each lamp four times for 20 seconds at an interval of 2 mins, while the DSC 7 recorded the heat flow developed during the treatment. The degree of conversion and the kinetic curves were calculated from the values of heat developed during each polymerization. The data were statistically analysed with a Kruskal-Wallis one-way ANOVA multiple range and Student-Newman-Keuls (SNK) tests at a P value of .05. Results: Statistically significant differences were found in the degree of conversion among the sealers: ER+A showed the highest values with both lamps. Conclusions: The higher polymerization rate in resin sealers is obtained with the addition of a catalyst. PMID:21494378

  4. Salt Stability - The Effect of pHmax on Salt to Free Base Conversion.

    PubMed

    Hsieh, Yi-Ling; Merritt, Jeremy M; Yu, Weili; Taylor, Lynne S

    2015-09-01

    The aim of this study was to investigate how the disproportionation process can be impacted by the properties of the salt, specifically pHmax. Five miconazole salts and four sertraline salts were selected for this study. The extent of conversion was quantified using Raman spectroscopy. A mathematical model was utilized to estimate the theoretical amount of conversion. A trend was observed that for a given series of salts of a particular basic compound (both sertraline and miconazole are bases), the extent of disproportionation increases as pHmax decreases. Miconazole phosphate monohydrate and sertraline mesylate, although exhibiting significantly different pHmax values (more than 2 units apart), underwent a similar extent of disproportionation, which may be attributed to the lower buffering capacity of sertraline salts. This work shows that the disproportionation tendency can be influenced by pHmax and buffering capacity and thus highlights the importance of selecting the appropriate salt form during the screening process in order to avoid salt-to-free form conversion.

  5. RNA-based tools for nuclear reprogramming and lineage-conversion: towards clinical applications.

    PubMed

    Bernal, Juan A

    2013-12-01

    The therapeutic potential of induced pluripotent stem cells (iPSCs) is well established. Safety concerns remain, however, and these have driven considerable efforts aimed at avoiding host genome alteration during the reprogramming process. At present, the tools used to generate human iPSCs include (1) DNA-based integrative and non-integrative methods and (2) DNA-free reprogramming technologies, including RNA-based approaches. Because of their combined efficiency and safety characteristics, RNA-based methods have emerged as the most promising tool for future iPSC-based regenerative medicine applications. Here, I will discuss novel recent advances in reprogramming technology, especially those utilizing the Sendai virus (SeV) and synthetic modified mRNA. In the future, these technologies may find utility in iPSC reprogramming for cellular lineage-conversion, and its subsequent use in cell-based therapies.

  6. Heterogeneous Catalytic Conversion of Dry Syngas to Ethanol and Higher Alcohols on Cu-Based Catalysts

    SciTech Connect

    Gupta, Mayank; Smith, Miranda L.; Spivey, James J.

    2011-04-19

    Ethanol and higher alcohols have been identified as potential fuel additives or hydrogen carriers for use in fuel cells. One method of ethanol production is catalytic conversion of syngas (a mixture of CO, H₂, CO₂, and H₂O), derived from biomass, coal, or natural gas. Thermodynamics of CO hydrogenation shows that ethanol is favored as the sole product at conditions of practical interest, but if methane is allowed as product in this analysis, essentially no ethanol is formed at equilibrium. The kinetics of ethanol formation must therefore be maximized. Although rhodium-based catalysts give C{sup 2+} oxygenates with high selectivity, their prohibitive cost has spurred research on less expensive copper-based alternatives. Copper-based catalysts require an optimum amount of promoter to suppress undesired reactions and maximize the yields of ethanol and higher alcohols. Common promoters include alkali, transition metals and their oxides, and rare earth oxides. Careful selection of operating variables is also necessary to achieve the desired activity and selectivity. This review describes the effects of promoters, supports, and operating conditions on the performance of copper-based catalysts for conversion of dry syngas to ethanol and higher alcohols. Proposed mechanisms from the literature for ethanol and higher-alcohol synthesis are outlined.

  7. Bases of Radio Direction Finding, Part II

    DTIC Science & Technology

    1977-12-22

    follows that during the determiaition of 1’ bearing from tcie resulting radiation pattern they are obtained in the get:eral case of er-or. Since the...phase earth-refleztel wive relatively falling directly for vertical and horizontal fiFli.; G is an operation of determining the bearing ( obtaining the...mtximum, minimum and so forth) ; g is the required for obtaining bearinj result (zero, the maximum value of lug/lobe, etc.). From Fig. 6.1 it follows

  8. OTDM to WDM format conversion based on quadratic cascading in a periodically poled lithium niobate waveguide.

    PubMed

    Lee, Kwang Jo; Liu, Sheng; Parmigiani, Francesca; Ibsen, Morten; Petropoulos, Periklis; Gallo, Katia; Richardson, David J

    2010-05-10

    We propose and demonstrate error-free conversion of a 40 Gbit/s optical time division multiplexed signal to 4 x 10 Gbit/s wavelength division multiplexed channels based on cascaded second harmonic and difference frequency generation in a periodically poled lithium niobate waveguide. The technique relies on the generation of spectrally (and temporally) flat linearly chirped pulses which are then optically switched with short data pulses in the nonlinear waveguide. Error-free operation was obtained for all channels with a power penalty below 2dB.

  9. Novel Control for Voltage Boosted Matrix Converter based Wind Energy Conversion System with Practicality

    NASA Astrophysics Data System (ADS)

    Kumar, Vinod; Joshi, Raghuveer Raj; Yadav, Dinesh Kumar; Garg, Rahul Kumar

    2017-04-01

    This paper presents the implementation and investigation of novel voltage boosted matrix converter (MC) based permanent magnet wind energy conversion system (WECS). In this paper, on-line tuned adaptive fuzzy control algorithm cooperated with reversed MC is proposed to yield maximum energy. The control system is implemented on a dSPACE DS1104 real time board. Feasibility of the proposed system has been experimentally verified using a laboratory 1.2 kW prototype of WECS under steady-state and dynamic conditions.

  10. Single-mode fiber laser based on core-cladding mode conversion.

    PubMed

    Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

    2008-02-15

    A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

  11. 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.

  12. Concept maps: A tool for knowledge management and synthesis in web-based conversational learning.

    PubMed

    Joshi, Ankur; Singh, Satendra; Jaswal, Shivani; Badyal, Dinesh Kumar; Singh, Tejinder

    2016-01-01

    Web-based conversational learning provides an opportunity for shared knowledge base creation through collaboration and collective wisdom extraction. Usually, the amount of generated information in such forums is very huge, multidimensional (in alignment with the desirable preconditions for constructivist knowledge creation), and sometimes, the nature of expected new information may not be anticipated in advance. Thus, concept maps (crafted from constructed data) as "process summary" tools may be a solution to improve critical thinking and learning by making connections between the facts or knowledge shared by the participants during online discussion This exploratory paper begins with the description of this innovation tried on a web-based interacting platform (email list management software), FAIMER-Listserv, and generated qualitative evidence through peer-feedback. This process description is further supported by a theoretical construct which shows how social constructivism (inclusive of autonomy and complexity) affects the conversational learning. The paper rationalizes the use of concept map as mid-summary tool for extracting information and further sense making out of this apparent intricacy.

  13. Concept maps: A tool for knowledge management and synthesis in web-based conversational learning

    PubMed Central

    Joshi, Ankur; Singh, Satendra; Jaswal, Shivani; Badyal, Dinesh Kumar; Singh, Tejinder

    2016-01-01

    Web-based conversational learning provides an opportunity for shared knowledge base creation through collaboration and collective wisdom extraction. Usually, the amount of generated information in such forums is very huge, multidimensional (in alignment with the desirable preconditions for constructivist knowledge creation), and sometimes, the nature of expected new information may not be anticipated in advance. Thus, concept maps (crafted from constructed data) as “process summary” tools may be a solution to improve critical thinking and learning by making connections between the facts or knowledge shared by the participants during online discussion This exploratory paper begins with the description of this innovation tried on a web-based interacting platform (email list management software), FAIMER-Listserv, and generated qualitative evidence through peer-feedback. This process description is further supported by a theoretical construct which shows how social constructivism (inclusive of autonomy and complexity) affects the conversational learning. The paper rationalizes the use of concept map as mid-summary tool for extracting information and further sense making out of this apparent intricacy. PMID:27563577

  14. 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.

  15. Evaluation of storage methods for the conversion of corn stover biomass to sugars based on steam explosion pretreatment.

    PubMed

    Liu, Zhi-Hua; Qin, Lei; Jin, Ming-Jie; Pang, Feng; Li, Bing-Zhi; Kang, Yong; Dale, Bruce E; Yuan, Ying-Jin

    2013-03-01

    Effects of dry and wet storage methods without or with shredding on the conversion of corn stover biomass were investigated using steam explosion pretreatment and enzymatic hydrolysis. Sugar conversions and yields for wet stored biomass were obviously higher than those for dry stored biomass. Shredding reduced sugar conversions compared with non-shredding, but increased sugar yields. Glucan conversion and glucose yield for non-shredded wet stored biomass reached 91.5% and 87.6% after 3-month storage, respectively. Data of micro-structure and crystallinity of biomass indicated that corn stover biomass maintained the flexible and porous structure after wet storage, and hence led to the high permeability of corn stover biomass and the high efficiency of pretreatment and hydrolysis. Therefore, the wet storage methods would be desirable for the conversion of corn stover biomass to fermentable sugars based on steam explosion pretreatment and enzymatic hydrolysis.

  16. Directionally solidified iron-base eutectic alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1976-01-01

    Pseudobinary eutectic alloys with nominal compositions of Fe-25Ta-22Ni-10Cr and Fe-15.5Nb-14.5Ni-6.0Cr were directionally solidified at 0.5 centimeter per hour. Their microstructure consisted of the fcc, iron solid-solution, matrix phase reinforced by about 41-volume-percent, hcp, faceted Fe2Ta fibers and 41-volume-percent, hcp, Fe2Nb lamellae for the tantalum- and niobium-containing alloys, respectively. The microstructural stability under thermal cycling and the temperature dependence of tensile properties were investigated. These alloys showed low elevated-temperature strength and were not considered suitable for application in aircraft-gas-turbine blades although they may have applicability as vane materials.

  17. Three-dimensional micro-printing of temperature sensors based on up-conversion luminescence

    NASA Astrophysics Data System (ADS)

    Wickberg, Andreas; Mueller, Jonathan B.; Mange, Yatin J.; Fischer, Joachim; Nann, Thomas; Wegener, Martin

    2015-03-01

    The pronounced temperature dependence of up-conversion luminescence from nanoparticles doped with rare-earth elements enables local temperature measurements. By mixing these nanoparticles into a commercially available photoresist containing the low-fluorescence photo-initiator Irgacure 369, and by using three-dimensional direct laser writing, we show that micrometer sized local temperature sensors can be positioned lithographically as desired. Positioning is possible in pre-structured environments, e.g., within buried microfluidic channels or on optical or electronic chips. We use the latter as an example and demonstrate the measurement for both free space and waveguide-coupled excitation and detection. For the free space setting, we achieve a temperature standard deviation of 0.5 K at a time resolution of 1 s.

  18. Three-dimensional micro-printing of temperature sensors based on up-conversion luminescence

    SciTech Connect

    Wickberg, Andreas; Mueller, Jonathan B.; Mange, Yatin J.; Nann, Thomas; Fischer, Joachim; Wegener, Martin

    2015-03-30

    The pronounced temperature dependence of up-conversion luminescence from nanoparticles doped with rare-earth elements enables local temperature measurements. By mixing these nanoparticles into a commercially available photoresist containing the low-fluorescence photo-initiator Irgacure 369, and by using three-dimensional direct laser writing, we show that micrometer sized local temperature sensors can be positioned lithographically as desired. Positioning is possible in pre-structured environments, e.g., within buried microfluidic channels or on optical or electronic chips. We use the latter as an example and demonstrate the measurement for both free space and waveguide-coupled excitation and detection. For the free space setting, we achieve a temperature standard deviation of 0.5 K at a time resolution of 1 s.

  19. Direct comparison of highly efficient solution- and vacuum-processed organic solar cells based on merocyanine dyes.

    PubMed

    Kronenberg, Nils M; Steinmann, Vera; Bürckstümmer, Hannah; Hwang, Jaehyung; Hertel, Dirk; Würthner, Frank; Meerholz, Klaus

    2010-10-01

    Identically configured bulk heterojunction organic solar cells based on merocyanine dye donor and fullerene acceptor compounds (see figure) are manufactured either from solution or by vacuum deposition, to enable a direct comparison. Whereas the former approach is more suitable for screening purposes, the latter approach affords higher short-circuit current density and power conversion efficiency.

  20. Community-Based Dialogue: Engaging Communities of Color in the United States’ Genetics Policy Conversation

    PubMed Central

    Bonham, Vence L.; Citrin, Toby; Modell, Stephen M.; Franklin, Tené Hamilton; Bleicher, Esther W. B.; Fleck, Leonard M.

    2009-01-01

    Engaging communities of color in the genetics public policy conversation is important for the translation of genetics research into strategies aimed at improving the health of all. Implementing model public participation and consultation processes can be informed by the Communities of Color Genetics Policy Project, which engaged individuals from African American and Latino communities of diverse socioeconomic levels in the process of “rational democratic deliberation” on ethical and policy issues stretching from genome research to privacy and discrimination concerns to public education. The results of the study included the development of a participatory framework based on a combination of the theory of democratic deliberation and the community-based public health model which we describe as “community-based dialogue.” PMID:19451407

  1. Community-based dialogue: engaging communities of color in the United states' genetics policy conversation.

    PubMed

    Bonham, Vence L; Citrin, Toby; Modell, Stephen M; Franklin, Tené Hamilton; Bleicher, Esther W B; Fleck, Leonard M

    2009-06-01

    Engaging communities of color in the genetics public policy conversation is important for the translation of genetics research into strategies aimed at improving the health of all. Implementing model public participation and consultation processes can be informed by the Communities of Color Genetics Policy Project, which engaged individuals from African American and Latino communities of diverse socioeconomic levels in the process of "rational democratic deliberation" on ethical and policy issues stretching from genome research to privacy and discrimination concerns to public education. The results of the study included the development of a participatory framework based on a combination of the theory of democratic deliberation and the community-based public health model which we describe as "community-based dialogue."

  2. 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

  3. Electrode Engineering of Conversion-based Negative Electrodes for Na-ion Batteries.

    PubMed

    Vogt, Leonie O; Marino, Cyril; Villevieille, Claire

    2015-01-01

    Due to lower costs and higher abundance of sodium, Na-ion battery technology can offer a good alternative to Li-ion batteries. Much research is focusing on developing new cathode and anode materials but the importance of the electrode engineering on the electrochemical performance is often neglected. The electrode composition is especially crucial for conversion reaction-based materials where the composite electrode (active material, conducting additive and binder) has to buffer the huge volume change occurring upon cycling. This work highlights the differences observed on Sn-CMC electrode performance by using different Sn particle sizes (micro- and nanoparticles) and evaluating the role of the conductive additive in the electrode. Carbon fibers (VGCF) demonstrate a good ability to surround micrometer particles but not especially nanometer particles leading to an improvement in the performance of microparticles but not of nanoparticles. For a high loading electrode suitable for full cell applications (>3.5 mg/cm(2) of active material), nanometer particles show limited performance for long-term cycling. The combination of VGCF with micrometer particles seems to be the most promising composition to obtain good performances for conversion reaction based-materials.

  4. All‐Copper Nanocluster Based Down‐Conversion White Light‐Emitting Devices

    PubMed Central

    Wang, Zhenguang; Chen, Bingkun; Susha, Andrei S.; Wang, Weihua; Reckmeier, Claas J.; Chen, Rui; Zhong, Haizheng

    2016-01-01

    Most of the present‐day down‐conversion white light‐emitting devices (WLEDs) utilize rare‐earth elements, which are expensive and facing the problem of shortage in supply. WLEDs based on the combination of orange and blue emitting copper nanoclusters are introduced, which are easy to produce and low in cost. Orange emitting Cu nanoclusters (NCs) are synthesized using glutathione as both the reduction agent and stabilizer, followed by solvent induced aggregation leading to the emission enhancement. Photoluminescence quantum yields (PL QY) of 24% and 43% in solution and solid state are achieved, respectively. Blue emitting Cu nanoclusters are synthesized by reduction of polyvinylpyrrolidone supported Cu(II) ions using ascorbic acid, followed by surface treatment with sodium citrate which improves both the emission intensity and stability of the clusters, resulting in the PL QY of 14% both in solution and solid state. All‐copper nanocluster based down‐conversion WLEDs are fabricated by integrating powdered orange and blue emitting Cu NC samples on a commercial GaN LED chip providing 370 nm excitation. They show favorable white light characteristics with Commission Internationale de l'Eclairage color coordinates, color rendering index, and correlated color temperature of (0.36, 0.31), 92, and 4163 K, respectively. PMID:27980993

  5. Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry.

    PubMed

    Norris, G; McConnell, G

    2010-03-01

    A novel bi-directional pump geometry that nonlinearly increases the nonlinear optical conversion efficiency of a synchronously pumped optical parametric oscillator (OPO) is reported. This bi-directional pumping method synchronizes the circulating signal pulse with two counter-propagating pump pulses within a linear OPO resonator. Through this pump scheme, an increase in nonlinear optical conversion efficiency of 22% was achieved at the signal wavelength, corresponding to a 95% overall increase in average power. Given an almost unchanged measured pulse duration of 260 fs under optimal performance conditions, this related to a signal wavelength peak power output of 18.8 kW, compared with 10 kW using the traditional single-pass geometry. In this study, a total effective peak intensity pump-field of 7.11 GW/cm(2) (corresponding to 3.55 GW/cm(2) from each pump beam) was applied to a 3 mm long periodically poled lithium niobate crystal, which had a damage threshold intensity of 4 GW/cm(2), without impairing crystal integrity. We therefore prove the application of this novel pump geometry provides opportunities for power-scaling of synchronously pumped OPO systems together with enhanced nonlinear conversion efficiency through relaxed damage threshold intensity conditions.

  6. Comparison of effective transverse piezoelectric coefficients e31,f of Pb(Zr,Ti)O3 thin films between direct and converse piezoelectric effects

    NASA Astrophysics Data System (ADS)

    Tsujiura, Yuichi; Kawabe, Saneyuki; Kurokawa, Fumiya; Hida, Hirotaka; Kanno, Isaku

    2015-10-01

    We evaluated the effective transverse piezoelectric coefficients (e31,f) of Pb(Zr,Ti)O3 (PZT) thin films from both the direct and converse piezoelectric effects of unimorph cantilevers. (001) preferentially oriented polycrystalline PZT thin films and (001)/(100) epitaxial PZT thin films were deposited on (111)Pt/Ti/Si and (001)Pt/MgO substrates, respectively, by rf-magnetron sputtering, and their piezoelectric responses owing to intrinsic and extrinsic effects were examined. The direct and converse |e31,f| values of the polycrystalline PZT thin films were calculated as 6.4 and 11.5-15.0 C/m2, respectively, whereas those of the epitaxial PZT thin films were calculated as 3.4 and 4.6-4.8 C/m2, respectively. The large |e31,f| of the converse piezoelectric property of the polycrystalline PZT thin films is attributed to extrinsic piezoelectric effects. Furthermore, the polycrystalline PZT thin films show a clear nonlinear piezoelectric contribution, which is the same as the Rayleigh-like behavior reported in bulk PZT. In contrast, the epitaxial PZT thin films on the MgO substrate show a piezoelectric response owing to the intrinsic and linear extrinsic effects, and no nonlinear contribution was observed.

  7. Photocatalytic direct conversion of ethanol to 1,1- diethoxyethane over noble-metal-loaded TiO2 nanotubes and nanorods.

    PubMed

    Zhang, Hongxia; Wu, Yupeng; Li, Li; Zhu, Zhenping

    2015-04-13

    As one of the most important biomass platform molecules, ethanol needs to have its product chain chemically extended to meet future demands in renewable fuels and chemicals. Additionally, chemical conversion of ethanol under mild and green conditions is still a major challenge. In this work, ethanol is directly converted into 1,1-diethoxyethane (DEE) and H2 under mild photocatalytic conditions over platinum-loaded TiO2 nanotubes and nanorods. The reaction follows a tandem dehydrogenation-acetalization mechanism, in which ethanol is first dehydrogenated into acetaldehyde and H(+) ion by photogenerated holes, and then acetalization between acetaldehyde and ethanol proceeds through promotion by H(+) ions formed in real time. Excess H(+) ions are simultaneously reduced into H2 by photogenerated electrons. This photocatalytic process has a very high reaction rate over nanosized tubular and rod-like TiO2 photocatalysts, reaching 157.7 mmol g(-1)  h(-1) in relatively low photocatalyst feeding. More importantly, the reaction is highly selective, with a nearly stoichiometric conversion of reacted ethanol into DEE. This photocatalytic dehydrogenation CO coupling of ethanol is a new green approach to the direct efficient conversion of ethanol into DEE and provides a promising channel for sustainable bioethanol applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Determination of CT-to-density conversion relationship for image-based treatment planning systems.

    PubMed

    Saw, Cheng B; Loper, Alphonse; Komanduri, Krishna; Combine, Tony; Huq, Saiful; Scicutella, Carol

    2005-01-01

    The implementation of tissue inhomogeneity correction in image-based treatment planning will improve the accuracy of radiation dose calculations for patients undergoing external-beam radiotherapy. Before the tissue inhomogeneity correction can be applied, the relationship between the computed tomography (CT) value and density must be established. This tissue characterization relationship allows the conversion of CT value in each voxel of the CT images into density for use in the dose calculations. This paper describes the proper procedure of establishing the CT value to density conversion relationship. A tissue characterization phantom with 17 inserts made of different materials was scanned using a GE Lightspeed Plus CT scanner (120 kVp). These images were then downloaded into the Eclipse and Pinnacle treatment planning systems. At the treatment planning workstation, the axial images were retrieved to determine the CT value of the inserts. A region of interest was drawn on the central portion of the insert and the mean CT value and its standard deviation were determined. The mean CT value was plotted against the density of the tissue inserts and fitted with bilinear equations. A new set of CT values vs. densities was generated from the bilinear equations and then entered into the treatment planning systems. The need to obtain CT values through the treatment planning system is very clear. The 2 treatment planning systems use different CT value ranges, one from -1024 to 3071 and the other from 0 to 4096. If the range is correct, it would result in inappropriate use of the conversion curve. In addition to the difference in the range of CT values, one treatment planning system uses physical density, while the other uses relative electron density.

  9. Direct conversion of cellulose to 1-(furan-2-yl)-2-hydroxyethanone in zinc chloride solution under microwave irradiation.

    PubMed

    Yang, Lei; Li, Gang; Yang, Fang; Zhang, Song-Mei; Fan, Hong-Xian; Lv, Xiao-Na

    2011-10-18

    Conversion of cellulose to 1-(furan-2-yl)-2-hydroxyethanone has been demonstrated in concentrated zinc chloride solution under microwave irradiation. Compared with the conventional oil-bath heating mode, microwave irradiation significantly reduced the reaction time and increased the yield of 1-(furan-2-yl)-2-hydroxyethanone. A typical degradation reaction with cellulose produced 1-(furan-2-yl)-2-hydroxyethanone in 12.0% molar yield in ZnCl(2) solution (ZnCl(2)-H(2)O ratio=2.25:1, w/w) with microwave irradiation at 600 W for 5 minutes at 135°C. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 10, January 1--March 31, 1989

    SciTech Connect

    Wilson, R.B. Jr.; Posin, B.M.; Chan, Yee Wai

    1989-05-19

    The goal of this research is to develop catalysts that directly convert methane and light hydrocarbons to intermediates that later can be converted to either liquid fuels or value-added chemicals, as economics dictate. In this reporting period, we have utilized samples of magnesia differing in their pretreatment temperature. Both the hydrido-ruthenium complex H{sub 4}Ru{sub 4}(CO){sub 12} and its reaction product with triethyl aluminum were reacted with these samples. The two ruthenium clusters are expected to react with the magnesia surface in different ways: by deprotonation of the hydride through an acid-base reaction with the basic surface, or by hydrolysis of the aluminum-carbon bond of the triethyl aluminum adduct. The concentration of hydroxyl groups on the magnesia surface able to hydrolyze the aluminum-carbon bond for immobilation should vary depending on the temperature of the pretreatment; the concentration of basic sites which can deprotonate the cluster should also vary with temperature. These differences were borne out by the experiment. We also compared the activity of two batches of AlRu{sub 4}/MgO which had been synthesized at different times in the project. Both batches had approximately the same activity, but the newer batch had greater selectivity for C{sub 6+} hydrocarbons.

  11. Polarization conversion based on an all-dielectric metasurface for optical fiber applications

    NASA Astrophysics Data System (ADS)

    Liu, Tongming; Yang, Sen; Tang, Donghua; Da, Haixia; Feng, Rui; Zhu, Tongtong; Sun, Fangkui; Ding, Weiqiang

    2017-08-01

    Polarization conversion (PC) in optical fiber is a very important operation in practice. To date, however, PC in fiber is usually achieved by coupling an external bulk element, or using the birefringence results from mechanically squeezing or coiling the fiber. In this paper, we propose a distinct approach for PC in optical fiber by introducing an all-dielectric metasurface in it, which has been proven to be compact, efficient and robust. Based on this approach, nearly perfect PCs from the linear polarization fundamental mode, i.e. {{LP}}01x mode to various other polarization modes, are achieved, including the {{LP}}01y mode, left/right-handed circular polarization mode, and also vector modes with radial and azimuthal polarizations. In addition, the fabrication of this all-dielectric-based metasurface is compatible with semiconductor manufacturing technologies, which makes the PC presented here competitive against traditional ones, and may find potential applications in optical fiber elements and systems.

  12. COMSOL-based Multiphysics Simulations to Support HFIR s Conversion to LEU Fuel

    SciTech Connect

    Jain, Prashant K; Freels, James D; Cook, David Howard

    2011-01-01

    In this paper, development of at least one form of the COMSOL-based modeling framework for the HFIR is presented, key simulation steps are identified and several milestones achieved towards a coupled multi-physics capability are highlighted. COMSOL-based multi-physics simulation capability is able to answer the need for predictive 3D simulations of HFIR s involute plate and channels. Step-by-step development and analyses of the COMSOL models for the single and multi-channels will lead towards the desired full-core simulation capability for the HFIR. With very few experiments planned to support the conversion process, these 3D simulations will become the basis for the nuclear safety analysis of the HFIR s LEU fuel core.

  13. Simplified 2-bit photonic digital-to-analog conversion unit based on polarization multiplexing

    NASA Astrophysics Data System (ADS)

    Zhang, Fangzheng; Gao, Bindong; Ge, Xiaozhong; Pan, Shilong

    2016-03-01

    A 2-bit photonic digital-to-analog conversion unit is proposed and demonstrated based on polarization multiplexing. The proposed 2-bit digital-to-analog converter (DAC) unit is realized by optical intensity weighting and summing, and its complexity is greatly reduced compared with the traditional 2-bit photonic DACs. Performance of the proposed 2-bit DAC unit is experimentally investigated. The established 2-bit DAC unit achieves a good linear transfer function, and the effective number of bits is calculated to be 1.3. Based on the proposed 2-bit DAC unit, two DAC structures with higher (>2) bit resolutions are proposed and discussed, and the system complexity is expected to be reduced by half by using the proposed technique.

  14. Wavelength conversion of 28 GBaud 16-QAM signals based on four-wave mixing in a silicon nanowire.

    PubMed

    Adams, Rhys; Spasojevic, Mina; Chagnon, Mathieu; Malekiha, Mahdi; Li, Jia; Plant, David V; Chen, Lawrence R

    2014-02-24

    We demonstrate error-free wavelength conversion of 28 GBaud 16-QAM single polarization (112 Gb/s) signals based on four-wave mixing in a dispersion engineered silicon nanowire (SNW). Wavelength conversion covering the entire C-band is achieved using a single pump. We characterize the performance of the wavelength converter subsystem through the electrical signal to noise ratio penalty as well as the bit error rate of the converted signal as a function of input signal power. Moreover, we evaluate the degradation of the optical signal to noise ratio due to wavelength conversion in the SNW.

  15. Toward Low-Voltage and Bendable X-Ray Direct Detectors Based on Organic Semiconducting Single Crystals.

    PubMed

    Ciavatti, Andrea; Capria, Ennio; Fraleoni-Morgera, Alessandro; Tromba, Giuliana; Dreossi, Diego; Sellin, Paul J; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2015-11-25

    Organic materials have been mainly proposed as ionizing radiation detectors in the indirect conversion approach. The first thin and bendable X-ray direct detectors are realized (directly converting X-photons into an electric signal) based on organic semiconducting single crystals that possess enhanced sensitivity, low operating voltage (≈5 V), and a minimum detectable dose rate of 50 μGy s(-1) .

  16. Low Noise and Highly Linear Wideband CMOS RF Front-End for DVB-H Direct-Conversion Receiver

    NASA Astrophysics Data System (ADS)

    Nam, Ilku; Moon, Hyunwon; Woo, Doo Hyung

    In this paper, a wideband CMOS radio frequency (RF) front-end for digital video broadcasting-handheld (DVB-H) receiver is proposed. The RF front-end circuit is composed of a single-ended resistive feedback low noise amplifier (LNA), a single-to-differential amplifier, an I/Q down-conversion mixer with linearized transconductors employing third order intermodulation distortion cancellation, and a divide-by-two circuit with LO buffers. By employing a third order intermodulation (IMD3) cancellation technique and vertical NPN bipolar junction transistor (BJT) switching pair for an I/Q down-conversion mixer, the proposed RF front-end circuit has high linearity and low low-frequency noise performance. It is fabricated in a 0.18µm deep n-well CMOS technology and draws 12mA from a 1.8V supply voltage. It shows a voltage gain of 31dB, a noise figure (NF) lower than 2.6dB, and an IIP3 of -8dBm from 470MHz to 862MHz.

  17. 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.

  18. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 4, August 16--October 15, 1987

    SciTech Connect

    Wilson, R.B. Jr.; Chan, Yee Wai

    1987-11-19

    The goals of this research project are to increase the methane conversion and improve the hydrocarbon production. For methane reforming, we achieved a conversion of up to 43% by adjusting the reaction conditions. Ruthenium clusters are effective catalysts but the selectivity to hydrocarbons needs to be improved. In evaluating the effect of cluster size for mononuclear, tetranuclear, and hexanuclear ruthenium complexes we found that the tetraruthenium cluster was by far the most effective catalyst. We began to study the mixed metal catalysts by synthesizing a FeRu{sub 3} cluster. We plan to vary the ratio of Fe to Ru by synthesizing Fe{sub 2}Ru{sub 2} and Fe{sub 3}Ru clusters. The type of the support also plays an important role in methane reforming. We briefly tested a basic support, magnesia, in addition to the acidic supports tested previously (alumina, 5A molecular sieve, and Y-zeolite). The results are promising. We will continue to investigate the role of the support. The effectiveness of using a hydrogen removal membrane is still in question. We purchased a new Pd/Ag membrane tube inside which a stainless steel spring is inserted. The steel spring will increase the strength of the otherwise fragile tube and it will support the tube during bending. We will build a new reactor using this membrane tube.

  19. Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide

    PubMed Central

    Sun, Feiran; Sun, Zhenguo; Chen, Qiang; Murayama, Riichi; Nishino, Hideo

    2016-01-01

    To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT) for S0-wave and a periodic permanent magnet (PPM) EMAT for SH0-wave were developed and optimized. Then, several comparison experiments were conducted to compare the efficiency of mode conversion. Experimental results showed that the T(0,1) mode, L(0,1) mode, and L(0,2) mode guided waves can be successfully detected when converted from the S0-wave or SH0-wave with different shaped waveguides. It can also be inferred that the S0-wave has a better ability to convert to the T(0,1) mode, while the SH0-wave is easier to convert to the L(0,1) mode and L(0,2) mode, and the L-shaped waveguide has a better efficiency than T-shaped waveguide. PMID:27775580

  20. The surface and electrochemical analysis of permanganate based conversion coating on alclad and unclad 2024 alloy

    NASA Astrophysics Data System (ADS)

    Yoganandan, G.; Balaraju, J. N.; William Grips, V. K.

    2012-09-01

    In the present investigation permanganate based conversion coating (PCC) was developed on AA 2024 alloy using alkaline bath containing Mn/Mo oxyanions. Conversion coating was formed on alclad (APCC) and unclad (UPCC) aluminium alloys by simple immersion method. Surface morphology of the APCC and UPCC specimens exhibited smooth and mud-crack patterns respectively. Elemental analysis showed the presence of higher amounts of Mn (5-6 wt.%) and Mo (0.3 wt.%) on UPCC. Raman and XPS analysis showed the presence of compounds such as MnOx (Mn3O4 and Mn2O3), MnO2, KMnO4, MoOx, MoO2, MoO3/polymolybdate on both coating surfaces. The corrosion current density (icorr) values obtained for both coated surfaces were less than 1 μA/cm2. However, APCC specimen showed the lowest icorr value of about 0.05 μA/cm2 after 168 h of immersion in 3.5% NaCl. EIS studies revealed the higher charge transfer resistance (Rct) values for APCC specimen after 1 and 168 h immersion compared to UPCC. Coated specimens were also tested by continuous salt spray exposure (ASTM B117) with and without cross-hatch mark ('X') for about 750 h. Coating discoloration along with the presence of few corrosion products had been noticed on UPCC specimen after continuous salt spray exposure.

  1. Terahertz-wave differential detection based on simultaneous dual-wavelength up-conversion

    NASA Astrophysics Data System (ADS)

    Takida, Yuma; Nawata, Kouji; Suzuki, Safumi; Asada, Masahiro; Minamide, Hiroaki

    2017-03-01

    We report a terahertz (THz)-wave differential detection based on simultaneous dual-wavelength up-conversion in a nonlinear optical MgO:LiNbO3 crystal with optical and electronic THz-wave sources. The broadband parametric gain and noncollinear phase-matching of MgO:LiNbO3 provide efficient conversion from superposed THz waves to spatially distributed near-infrared (NIR) beams to function as a dispersive THz-wave spectrometer without any additional dispersive element. We show that the μW-level THz waves from two independent sources, a 0.78-THz injection-seeded THz-wave parametric generator (is-TPG) and a 1.14-THz resonant tunneling diode (RTD), are simultaneously up-converted to two NIR waves and then detected with two NIR photodetectors. By applying a balanced detection scheme to this dual-frequency detection, we demonstrate THz-wave differential imaging of maltose and polyethylene pellets in the transmission geometry. This dual-wavelength detection is applicable to more than three frequencies and broadband THz-wave radiation for real-time THz-wave spectroscopic detection and imaging.

  2. Optical frequency comb based multi-band microwave frequency conversion for satellite applications.

    PubMed

    Yang, Xinwu; Xu, Kun; Yin, Jie; Dai, Yitang; Yin, Feifei; Li, Jianqiang; Lu, Hua; Liu, Tao; Ji, Yuefeng

    2014-01-13

    Based on optical frequency combs (OFC), we propose an efficient and flexible multi-band frequency conversion scheme for satellite repeater applications. The underlying principle is to mix dual coherent OFCs with one of which carrying the input signal. By optically channelizing the mixed OFCs, the converted signal in different bands can be obtained in different channels. Alternatively, the scheme can be configured to generate multi-band local oscillators (LO) for widely distribution. Moreover, the scheme realizes simultaneous inter- and intra-band frequency conversion just in a single structure and needs only three frequency-fixed microwave sources. We carry out a proof of concept experiment in which multiple LOs with 2 GHz, 10 GHz, 18 GHz, and 26 GHz are generated. A C-band signal of 6.1 GHz input to the proposed scheme is successfully converted to 4.1 GHz (C band), 3.9 GHz (C band) and 11.9 GHz (X band), etc. Compared with the back-to-back (B2B) case measured at 0 dBm input power, the proposed scheme shows a 9.3% error vector magnitude (EVM) degradation at each output channel. Furthermore, all channels satisfy the EVM limit in a very wide input power range.

  3. Catalytic Conversion of Carbohydrates to Levulinate Ester over Heteropolyanion-Based Ionic Liquids.

    PubMed

    Song, Changhua; Liu, Sijie; Peng, Xinwen; Long, Jinxing; Lou, Wenyong; Li, Xuehui

    2016-12-08

    An efficient one-pot approach for the production of levulinate ester from renewable carbohydrates is demonstrated over heteropolyanion-based ionic liquid (IL-POM) catalysts with alcohols as the promoters and solvents. The relationships between the structure, acidic strength, and solubility of the IL-POM in methanol and the catalytic performance were studied intensively. A cellulose conversion of 100 % could be achieved with a 71.4 % yield of methyl levulinate over the catalyst [PyPS]3 PW12 O40 [PyPS=1-(3-sulfopropyl)pyridinium] at 150 °C for 5 h. This high efficiency is ascribed to the reasonably high activity of the ionic liquid (IL) catalyst and reaction coupling with rapid in situ esterification of the generated levulinic acid with the alcohol promoter, which allows the insolubility of cellulose encountered in biomass conversion to be overcome. Furthermore, the present process exhibits high feedstock adaptability for typical carbohydrates and handy catalyst recovery by a simple self-separation procedure through temperature control. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide.

    PubMed

    Sun, Feiran; Sun, Zhenguo; Chen, Qiang; Murayama, Riichi; Nishino, Hideo

    2016-10-19

    To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT) for S0-wave and a periodic permanent magnet (PPM) EMAT for SH0-wave were developed and optimized. Then, several comparison experiments were conducted to compare the efficiency of mode conversion. Experimental results showed that the T(0,1) mode, L(0,1) mode, and L(0,2) mode guided waves can be successfully detected when converted from the S0-wave or SH0-wave with different shaped waveguides. It can also be inferred that the S0-wave has a better ability to convert to the T(0,1) mode, while the SH0-wave is easier to convert to the L(0,1) mode and L(0,2) mode, and the L-shaped waveguide has a better efficiency than T-shaped waveguide.

  5. Efficient Conversion of Lignin to Electricity Using a Novel Direct Biomass Fuel Cell Mediated by Polyoxomethalates at Low Temperatures

    Treesearch

    Xuebing Zhao; Junyong Zhu

    2016-01-01

    A novel polyoxometalates (POMs) mediated direct biomass fuelcelI (DBFC) was used in this study to directly convert lignin to electricity at low temperatures with high power output and Faradaic efficiency. When phosphomolybdic acid H3PMo12O40 (PMo12) was used as the electron and...

  6. All-optical NRZ wavelength conversion based on a single hybrid III-V/Si SOA and optical filtering.

    PubMed

    Wu, Yingchen; Huang, Qiangsheng; Keyvaninia, Shahram; Katumba, Andrew; Zhang, Jing; Xie, Weiqiang; Morthier, Geert; He, Jian-Jun; Roelkens, Gunther

    2016-09-05

    We demonstrate all-optical wavelength conversion (AOWC) of non-return-to-zero (NRZ) signal based on cross-gain modulation in a single heterogeneously integrated III-V-on-silicon semiconductor optical amplifier (SOA) with an optical bandpass filter. The SOA is 500 μm long and consumes less than 250 mW electrical power. We experimentally demonstrate 12.5 Gb/s and 40 Gb/s AOWC for both wavelength up and down conversion.

  7. Scalable Synthesis of Graphene Based Heterostructures and Their Use in Energy Sensing, Conversion and Storage

    NASA Astrophysics Data System (ADS)

    Bhimanapati, Ganesh Rahul

    2D materials are a unique class of materials system which has spread across the entire spectrum of materials including semi-metallic graphene to insulating boron nitride. Since graphene there has been many other 2D material systems (such as boron nitride (hBN), transition metal dichalcogenides (TMDs)) that provide a wider array of unique chemistries and properties to explore for applications specifically in optoelectronics, mechanical and energy applications. Specifically tailored heterostructures can be made which can retain the character of single-atom thick sheets while having an entirely different optical and mechanical properties compared to the parent materials. In the current work, heterostructures based on graphene, hBN and TMDs have been made, which were used to study the fundamental process-property relations and their use in energy conversion and storage have been studied. The first part of this dissertation focuses on scalable approach for liquid phase exfoliation of graphene oxide (GO) and hBN (Chapter 2). The current work successfully shows an exfoliation efficiency of 25% monolayer material for hBN, which was not previously achieved. These exfoliated materials were further mixed in the liquid environment to form a new heterostructure BCON (Chapter 3). This newly formed heterostructure was studied in detail for its process-property relations. At pH 4-8, BCON was highly stable and can be dried to form paper or ribbon like material. New bonds were observed in BCON which could be linked to the GO linkage at the nitrogen sites of the hBN. This free standing BCON was tested under various radiation sources like x-rays, alpha, beta, gamma sources and heavy ion like Ar particles and was found that it is very robust to radiation (Chapter 5). By understanding the chemistry, stability and properties of these materials, this could lay a foundation in using these materials for integration in conductive and insulating ink development, polymer composite development

  8. VR-based conversation training program for patients with schizophrenia: a preliminary clinical trial.

    PubMed

    Ku, Jeonghun; Han, Kiwan; Lee, Hyung Rae; Jang, Hee Jeong; Kim, Kwang Uk; Park, Sung Hyouk; Kim, Jae Jin; Kim, Chan Hyung; Kim, In Young; Kim, Sun I

    2007-08-01

    Schizophrenia is a devastating mental illness and is characterized by hallucinations and delusions as well as social skills deficits. Generally, social skills training designed to help patients develop social skills includes role-playing, but this form of training has typical shortcomings, which are largely due to a trainer's difficulties to project emotion. Virtual reality (VR)-based techniques have the potential to solve these difficulties, because they provide a computer-generated but realistic three-dimensional world and humanlike avatars that can provide emotional stimuli. In this paper, we report on a method of implementing virtual environments (VEs) in order to train people with schizophrenia to develop conversational skills in specific situations, which could overcome the shortcomings of or complement conventional role-playing techniques. The paper reports the efficacy of the proposed approach in a preliminary clinical trial with 10 patients with schizophrenia.

  9. Novel grid-based optical Braille conversion: from scanning to wording

    NASA Astrophysics Data System (ADS)

    Yoosefi Babadi, Majid; Jafari, Shahram

    2011-12-01

    Grid-based optical Braille conversion (GOBCO) is explained in this article. The grid-fitting technique involves processing scanned images taken from old hard-copy Braille manuscripts, recognising and converting them into English ASCII text documents inside a computer. The resulted words are verified using the relevant dictionary to provide the final output. The algorithms employed in this article can be easily modified to be implemented on other visual pattern recognition systems and text extraction applications. This technique has several advantages including: simplicity of the algorithm, high speed of execution, ability to help visually impaired persons and blind people to work with fax machines and the like, and the ability to help sighted people with no prior knowledge of Braille to understand hard-copy Braille manuscripts.

  10. Design and synthesis of chlorinated benzothiadiazole-based polymers for efficient solar energy conversion

    DOE PAGES

    Hu, Zhiming; Chen, Hui; Qu, Jianfei; ...

    2017-03-10

    Here, chlorinated benzothiadiazide based polymers with multiple chlorine atoms has been designed and synthesized for polymer solar cells with enhanced open circuit voltage up to 0.85 V. The chlorine substitution is found to significantly adjust the band gap of the polymers, and change polymer’s orientation from random morphology of chlorine free PBT4T-2OD, to mixed face-on packing of one chlorine substituted PCBT4T-2OD, and finally to edge-on of two chlorine substituted PCCBT4T-2OD. The optimized chlorinated polymer, PCBT4T-2OD with only one chlorine atom substituted on BT moiety, has been founded to achieve the highest power conversion efficiency up to 8.20% with PC71BM, whichmore » is about 68% higher than that of its non-chlorine analogues.« less

  11. Remanufacture of Zirconium-Based Conversion Coatings on the Surface of Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Jin, Guo; Song, Jiahui; Cui, Xiufang; Cai, Zhaobing

    2017-04-01

    Brush plating provides an effective method for creating a coating on substrates of various shapes. A corroded zirconium-based conversion coating was removed from the surface of a magnesium alloy and then replaced with new coatings prepared via brush plating. The structure and composition of the remanufactured coating were determined via x-ray photoelectron spectroscopy, x-ray diffraction, and Fourier transform infrared spectroscopy. The results revealed that the coatings consist of oxide, fluoride, and tannin-related organics. The composition of the coatings varied with the voltage. Furthermore, as revealed via potentiodynamic polarization spectroscopy, these coatings yielded a significant increase in the corrosion resistance of the magnesium alloy. The friction coefficient remained constant for almost 300s during wear resistance measurements performed under a 1-N load and dry sliding conditions, indicating that the remanufactured coatings provide effective inhibition to corrosion.

  12. Conversations about curriculum change: mathematical thinking and team-based learning in a discrete mathematics course

    NASA Astrophysics Data System (ADS)

    Paterson, Judy; Sneddon, Jamie

    2011-10-01

    This article reports on the learning conversations between a mathematician and a mathematics educator as they worked together to change the delivery model of a third year discrete mathematics course from a traditional lecture mode to team-based learning (TBL). This change prompted the mathematician to create team tasks which increasingly focused on what he calls the 'unspoken curriculum': mathematical thinking. We consider the ways in which the TBL model promoted and enabled this in the light of literature on mathematical thinking, sense-making and behaviours, and strongly suggest that this approach warrants more attention from the mathematics teaching community. We also discuss shifts in the mathematician's thinking about task construction as he refined the tasks to encourage students to think and behave like mathematicians.

  13. Space-Based Solar Power Conversion and Delivery Systems Study. Volume 1: Executive Summary

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The research concerning space-based solar power conversion and delivery systems is summarized. The potential concepts for a photovoltaic satellite solar power system was studied with emphasis on ground output power levels of 5,000 MW and 10,000 MW. A power relay satellite, and certain aspects of the economics of these systems were also studied. A second study phase examined in greater depth the technical and economic aspects of satellite solar power systems. Throughout this study, the focus was on the economics of satellite solar power. The results indicate technical feasibility of the concept, and provide a preliminary economic justification for the first phase of a substantial development program. A development program containing test satellites is recommended. Also, development of alternative solar cell materials (other than silicon) is recommended.

  14. Remanufacture of Zirconium-Based Conversion Coatings on the Surface of Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Jin, Guo; Song, Jiahui; Cui, Xiufang; Cai, Zhaobing

    2017-03-01

    Brush plating provides an effective method for creating a coating on substrates of various shapes. A corroded zirconium-based conversion coating was removed from the surface of a magnesium alloy and then replaced with new coatings prepared via brush plating. The structure and composition of the remanufactured coating were determined via x-ray photoelectron spectroscopy, x-ray diffraction, and Fourier transform infrared spectroscopy. The results revealed that the coatings consist of oxide, fluoride, and tannin-related organics. The composition of the coatings varied with the voltage. Furthermore, as revealed via potentiodynamic polarization spectroscopy, these coatings yielded a significant increase in the corrosion resistance of the magnesium alloy. The friction coefficient remained constant for almost 300s during wear resistance measurements performed under a 1-N load and dry sliding conditions, indicating that the remanufactured coatings provide effective inhibition to corrosion.

  15. Giant and broadband circular asymmetric transmission based on two cascading polarization conversion cavities.

    PubMed

    Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Lu, Wei

    2016-04-21

    In this paper, a three-layered sandwiched metamaterial is proposed to achieve giant and broadband asymmetric transmission of circularly polarized waves at the near-infrared communication band. The metamaterial consists of two layers of identical 45° tilted chiral S-shaped metasurfaces sandwiched with a subwavelength metallic grating. Based on the delicate combination of broadband polarization conversion and a cavity-enhanced effect, the asymmetric parameter can reach a maximum value of 0.87 and over 0.6 in a wide range from 1.2 to 2.0 μm, which has not been found in previous reports. Furthermore, a perfect robustness to misalignments is obtained as the effect originated from function-independent cascading cavities, which effectively reduce the requirement of alignment precision in layer-by-layer photolithography processes. The proposed nanostructure has a great potential to be used as a circular polarization rotator or diode-like device in optical communication systems.

  16. Direct sulfation of limestone based on oxy-fuel combustion technology

    SciTech Connect

    Chen, C.M.; Zhao, C.S.; Liu, S.T.; Wang, C.B.

    2009-10-15

    With limestone as the sorbent, the sulfation reaction can proceed via two different routes depending on whether calcination of the limestone takes place under the given reaction conditions. The direct sulfation reaction is defined as the sulfation reaction between sulfur dioxide (SO{sub 2}) and limestone in an uncalcined state. This reaction, based on oxyfuel combustion technology, was studied by thermogravimetric analysis. Surface morphologies of the limestone particles after sulfation were examined by a scanning electron microscope. Results show that there are more pores or gaps in the product layer formed by direct sulfation of limestone than by indirect sulfation, which can be attributed to the generation of carbon dioxide (CO{sub 2}) at a reaction interface. Compared with indirect sulfation, direct sulfation of limestone can yield much higher conversion and has a much higher reaction rate. For direct sulfation, the greater porosity in the product layer greatly reduces the solid-state ion diffusion distance, resulting in a higher reaction rate and higher conversion.

  17. Energy-based coordinated control of wind energy conversion system with DFIG

    NASA Astrophysics Data System (ADS)

    Qu, Y. B.; Song, H. H.

    2011-12-01

    This article presents an energy-based coordinated control of machine- and grid-side converters in a wind energy conversion system (WECS) with a doubly-fed induction generator (DFIG) based on the theory of port-controlled Hamiltonian (PCH) system. Taking into account energy transmission in the dual PWM converter rather than treating rectification and inversion as separate parts, an integrated PCH model for the whole WECS was established from physical meanings. And depending on the new model, an energy-based coordinated control approach was proposed to meet the control requirements of the WECS with an additional objective which was to limit the DC-link voltage fluctuation. The approach was applied on a 2MW WECS, and compared with the energy-based respective control strategy using MATLAB/Simulink. The results show that the proposed control approach provides faster dynamic performance since the two converters operate with the knowledge of each other's operating status, and thus is able to smooth the power flow in the DC-link more effectively.

  18. Nanostructured Mn-based oxides for electrochemical energy storage and conversion.

    PubMed

    Zhang, Kai; Han, Xiaopeng; Hu, Zhe; Zhang, Xiaolong; Tao, Zhanliang; Chen, Jun

    2015-02-07

    Batteries and supercapacitors as electrochemical energy storage and conversion devices are continuously serving for human life. The electrochemical performance of batteries and supercapacitors depends in large part on the active materials in electrodes. As an important family, Mn-based oxides have shown versatile applications in primary batteries, secondary batteries, metal-air batteries, and pseudocapacitors due to their high activity, high abundance, low price, and environmental friendliness. In order to meet future market demand, it is essential and urgent to make further improvements in energy and power densities of Mn-based electrode materials with the consideration of multiple electron reaction and low molecular weight of the active materials. Meanwhile, nanomaterials are favourable to achieve high performance by means of shortening the ionic diffusion length and providing large surface areas for electrode reactions. This article reviews the recent efforts made to apply nanostructured Mn-based oxides for batteries and pseudocapacitors. The influence of structure, morphology, and composition on electrochemical performance has been systematically summarized. Compared to bulk materials and notable metal catalysts, nanostructured Mn-based oxides can promote the thermodynamics and kinetics of the electrochemical reactions occurring at the solid-liquid or the solid-liquid-gas interface. In particular, nanostructured Mn-based oxides such as one-dimensional MnO2 nanostructures, MnO2-conductive matrix nanocomposites, concentration-gradient structured layered Li-rich Mn-based oxides, porous LiNi0.5Mn1.5O4 nanorods, core-shell structured LiMnSiO4@C nanocomposites, spinel-type Co-Mn-O nanoparticles, and perovskite-type CaMnO3 with micro-nano structures all display superior electrochemical performance. This review should shed light on the sustainable development of advanced batteries and pseudocapacitors with nanostructured Mn-based oxides.

  19. Direct Conversion of Equine Adipose-Derived Stem Cells into Induced Neuronal Cells Is Enhanced in Three-Dimensional Culture.

    PubMed

    Petersen, Gayle F; Hilbert, Bryan J; Trope, Gareth D; Kalle, Wouter H J; Strappe, Padraig M

    2015-12-01

    The ability to culture neurons from horses may allow further investigation into equine neurological disorders. In this study, we demonstrate the generation of induced neuronal cells from equine adipose-derived stem cells (EADSCs) using a combination of lentiviral vector expression of the neuronal transcription factors Brn2, Ascl1, Myt1l (BAM) and NeuroD1 and a defined chemical induction medium, with βIII-tubulin-positive induced neuronal cells displaying a distinct neuronal morphology of rounded and compact cell bodies, extensive neurite outgrowth, and branching of processes. Furthermore, we investigated the effects of dimensionality on neuronal transdifferentiation, comparing conventional two-dimensional (2D) monolayer culture against three-dimensional (3D) culture on a porous polystyrene scaffold. Neuronal transdifferentiation was enhanced in 3D culture, with evenly distributed cells located on the surface and throughout the scaffold. Transdifferentiation efficiency was increased in 3D culture, with an increase in mean percent conversion of more than 100% compared to 2D culture. Additionally, induced neuronal cells were shown to transit through a Nestin-positive precursor state, with MAP2 and Synapsin 2 expression significantly increased in 3D culture. These findings will help to increase our understanding of equine neuropathogenesis, with prospective roles in disease modeling, drug screening, and cellular replacement for treatment of equine neurological disorders.

  20. Direct observation of spin-to-charge conversion in MoS2 monolayer with spin pumping

    NASA Astrophysics Data System (ADS)

    Cheng, Cheng; Ivanovskaya, Viktoria; Rojas Sanchez, Juan-Carlos; Dlubak, Bruno; Seneor, Pierre; Lee, Young Hee; Han, Ganghee; Kim, Hyun; Yang, Heejun; Anane, Abdelmadjid

    2015-03-01

    Unlike graphene, layered transition-metal dichalcogenides are 2D wide bandgap semiconductors with large intrinsic spin-orbit coupling (SOC) and valley-spin coupling, which makes them a unique playground for spintronics. We present here the first demonstration of spin injection into monolayer MoS2 with spin pumping from a 3D ferromagnetic (FM) film, circumventing the impedance mismatch at the metal-semiconductor interface. We measured the transverse voltage generated by spin-to-charge current conversion in MoS2 with broadband (3 GHz- 9 GHz) ferromagnetic resonance (FMR) setup. The observed symmetric Lorentzian signals are in 1 μV range under small rf excitations well below 1 Oe. This voltage magnitude is unexpected for inverse spin Hall effect and is interpreted in the frame of inverse Rashba-Edelstein effect (iREE) due to strong SOC in MoS2. By applying a moderate gate voltage (up to 10 V) on the MoS2/FM multilayer, we observe clear modulation (up to 30%) of the linewidth and amplitude of the iREE signal, indicating electrical tuning of the spin mixing conductance.

  1. Direct Conversion of CH3NH3PbI3 from Electrodeposited PbO for Highly Efficient Planar Perovskite Solar Cells

    PubMed Central

    Huang, Jin-hua; Jiang, Ke-jian; Cui, Xue-ping; Zhang, Qian-qian; Gao, Meng; Su, Mei-ju; Yang, Lian-ming; Song, Yanlin

    2015-01-01

    Organic-inorganic hybrid perovskite materials have recently been identified as a promising light absorber for solar cells. In the efficient solar cells, the perovskite active layer has generally been fabricated by either vapor deposition or two-step sequential deposition process. Herein, electrochemically deposited PbO film is in situ converted into CH3NH3PbI3 through solid-state reaction with adjacent CH3NH3I layer, exhibiting a large-scale flat and uniform thin film with fully substrate coverage. The resultant planar heterojunction photovoltaic device yields a best power conversion efficiency of 14.59% and an average power conversion efficiency of 13.12 ± 1.08% under standard AM 1.5 conditions. This technique affords a facile and environment-friendly method for the fabrication of the perovskite based solar cells with high reproducibility, paving the way for the practical application. PMID:26510520

  2. Direct Conversion of CH3NH3PbI3 from Electrodeposited PbO for Highly Efficient Planar Perovskite Solar Cells.

    PubMed

    Huang, Jin-hua; Jiang, Ke-jian; Cui, Xue-ping; Zhang, Qian-qian; Gao, Meng; Su, Mei-ju; Yang, Lian-ming; Song, Yanlin

    2015-10-29

    Organic-inorganic hybrid perovskite materials have recently been identified as a promising light absorber for solar cells. In the efficient solar cells, the perovskite active layer has generally been fabricated by either vapor deposition or two-step sequential deposition process. Herein, electrochemically deposited PbO film is in situ converted into CH3NH3PbI3 through solid-state reaction with adjacent CH3NH3I layer, exhibiting a large-scale flat and uniform thin film with fully substrate coverage. The resultant planar heterojunction photovoltaic device yields a best power conversion efficiency of 14.59% and an average power conversion efficiency of 13.12 ± 1.08% under standard AM 1.5 conditions. This technique affords a facile and environment-friendly method for the fabrication of the perovskite based solar cells with high reproducibility, paving the way for the practical application.

  3. Teaching as a Focussed Conversation: The Use of Incentive-Based Preparation Exercises

    ERIC Educational Resources Information Center

    Spiller, Peter

    2005-01-01

    In this case note I report on the introduction of incentive-based preparation exercises into my law teaching. These exercises require students, at each seminar class, to hand in a written summary of their responses to focussed questions on course materials. These questions are directly related to the work required for the final assessment in the…

  4. Two Quantum Direct Communication Protocols Based on Quantum Search Algorithm

    NASA Astrophysics Data System (ADS)

    Xu, Shu-Jiang; Chen, Xiu-Bo; Wang, Lian-Hai; Niu, Xin-Xin; Yang, Yi-Xian

    2015-07-01

    Based on the properties of two-qubit Grover's quantum search algorithm, we propose two quantum direct communication protocols, including a deterministic secure quantum communication and a quantum secure direct communication protocol. Secret messages can be directly sent from the sender to the receiver by using two-qubit unitary operations and the single photon measurement with one of the proposed protocols. Theoretical analysis shows that the security of the proposed protocols can be highly ensured.

  5. Revisiting Morrison and Osterle 1965: the efficiency of membrane-based electrokinetic energy conversion

    NASA Astrophysics Data System (ADS)

    Catalano, J.; Hamelers, H. V. M.; Bentien, A.; Biesheuvel, P. M.

    2016-08-01

    We revisit Morrison and Osterle (1965) who derived a phenomenological expression for the ‘figure-of-merit’ {β\\text{EK}} of the electrokinetic energy conversion (EKEC) of a pressure difference into electric energy (and vice versa) using charged nanotubes, nanopores or ion-exchange membranes. We show the equivalence with Morrison and Osterle of a novel expression of {β\\text{EK}} derived by Bentien et al (2013). We analyze two physical models for ionic and solvent flow which directly relate {β\\text{EK}} to nanopore characteristics such as pore size and wall charge density. For the uniform potential model, we derive an analytical expression as a function of pore size, viscosity, ion diffusion coefficients and membrane charge density, and compare results with the full space-charge model by Osterle and co-workers as a function of pore size and ion diffusion coefficient. We present a novel expression for {β\\text{EK}} for salt solutions with ions with unequal diffusion coefficients (mobilities) and show that to increase {β\\text{EK}} the counterion mobility must be low and the coion mobility high.

  6. Metallic-covalent bonding conversion and thermoelectric properties of Al-based icosahedral quasicrystals and approximants

    NASA Astrophysics Data System (ADS)

    Takagiwa, Yoshiki; Kimura, Kaoru

    2014-08-01

    In this article, we review the characteristic features of icosahedral cluster solids, metallic-covalent bonding conversion (MCBC), and the thermoelectric properties of Al-based icosahedral quasicrystals and approximants. MCBC is clearly distinguishable from and closely related to the well-known metal-insulator transition. This unique bonding conversion has been experimentally verified in 1/1-AlReSi and 1/0-Al12Re approximants by the maximum entropy method and Rietveld refinement for powder x-ray diffraction data, and is caused by a central atom inside the icosahedral clusters. This helps to understand pseudogap formation in the vicinity of the Fermi energy and establish a guiding principle for tuning the thermoelectric properties. From the electron density distribution analysis, rigid heavy clusters weakly bonded with glue atoms are observed in the 1/1-AlReSi approximant crystal, whose physical properties are close to icosahedral Al-Pd-TM (TM: Re, Mn) quasicrystals. They are considered to be an intermediate state among the three typical solids: metals, covalently bonded networks (semiconductor), and molecular solids. Using the above picture and detailed effective mass analysis, we propose a guiding principle of weakly bonded rigid heavy clusters to increase the thermoelectric figure of merit (ZT) by optimizing the bond strengths of intra- and inter-icosahedral clusters. Through element substitutions that mainly weaken the inter-cluster bonds, a dramatic increase of ZT from less than 0.01 to 0.26 was achieved. To further increase ZT, materials should form a real gap to obtain a higher Seebeck coefficient.

  7. Metallic-covalent bonding conversion and thermoelectric properties of Al-based icosahedral quasicrystals and approximants.

    PubMed

    Takagiwa, Yoshiki; Kimura, Kaoru

    2014-08-01

    In this article, we review the characteristic features of icosahedral cluster solids, metallic-covalent bonding conversion (MCBC), and the thermoelectric properties of Al-based icosahedral quasicrystals and approximants. MCBC is clearly distinguishable from and closely related to the well-known metal-insulator transition. This unique bonding conversion has been experimentally verified in 1/1-AlReSi and 1/0-Al12Re approximants by the maximum entropy method and Rietveld refinement for powder x-ray diffraction data, and is caused by a central atom inside the icosahedral clusters. This helps to understand pseudogap formation in the vicinity of the Fermi energy and establish a guiding principle for tuning the thermoelectric properties. From the electron density distribution analysis, rigid heavy clusters weakly bonded with glue atoms are observed in the 1/1-AlReSi approximant crystal, whose physical properties are close to icosahedral Al-Pd-TM (TM: Re, Mn) quasicrystals. They are considered to be an intermediate state among the three typical solids: metals, covalently bonded networks (semiconductor), and molecular solids. Using the above picture and detailed effective mass analysis, we propose a guiding principle of weakly bonded rigid heavy clusters to increase the thermoelectric figure of merit (ZT) by optimizing the bond strengths of intra- and inter-icosahedral clusters. Through element substitutions that mainly weaken the inter-cluster bonds, a dramatic increase of ZT from less than 0.01 to 0.26 was achieved. To further increase ZT, materials should form a real gap to obtain a higher Seebeck coefficient.

  8. Evaluation of quadrature-phase-shift-keying signal characteristics in W-band radio-over-fiber transmission using direct in-phase/quadrature-phase conversion technique

    NASA Astrophysics Data System (ADS)

    Suzuki, Meisaku; Kanno, Atsushi; Yamamoto, Naokatsu; Sotobayashi, Hideyuki

    2016-02-01

    The effects of in-phase/quadrature-phase (IQ) imbalances are evaluated with a direct IQ down-converter in the W-band (75-110 GHz). The IQ imbalance of the converter is measured within a range of +/-10 degrees in an intermediate frequency of DC-26.5 GHz. 1-8-G-baud quadrature phase-shift keying (QPSK) signals are transmitted successfully with observed bit error rates within a forward error correction limit of 2×10-3 using radio over fiber (RoF) techniques. The direct down-conversion technique is applicable to next-generation high-speed wireless access communication systems in the millimeter-wave band.

  9. Highly chemoselective and versatile method for direct conversion of carboxylic acids to ketones utilizing zinc ate complexes.

    PubMed

    Murata, Ryo; Hirano, Keiichi; Uchiyama, Masanobu

    2015-06-01

    Various carboxylic acids were directly transformed into the corresponding ketones by utilizing organozinc ate complexes, which provide high chemoselectivity without any overreaction to the undesired tertiary carbinol, owing to formation of a stable tetrahedral zincioketal intermediate. This method offers good overall atom/step/pot economy and operational simplicity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Direct observation of transition to electron Bernstein waves from electromagnetic mode by three mode-conversion scenarios in the dipole confinement torus plasma

    NASA Astrophysics Data System (ADS)

    Uchijima, K.; Takemoto, T.; Morikawa, J.; Ogawa, Y.

    2015-06-01

    Direct measurement experiments on the mode conversion to the electron Bernstein wave (EBW) have been conducted in dipole confinement torus plasmas for three excitation scenarios; i.e. perpendicular injections of an eXtraordinary mode (X-mode) from the low- and high-magnetic-field sides, and the oblique injection of an Ordinary mode (O-mode) from the low-magnetic-field side. By inserting probe antennas into plasmas, wave propagation has been directly measured. At plasma conditions for the EBW excitation, several characteristics which indicate the mode conversion to the EBWs have been observed; i.e. a short wavelength wave, an electrostatic and longitudinal mode, backward propagation at the upper hybrid resonance (UHR) region. Meanwhile, the wavelengths experimentally observed might be slightly longer than those of theoretical prediction. In the case of the oblique injection of the O-mode, it has been identified that the window of the injection angle for the excitation of the EBW would be quite limited, and the optimum angle seems to be roughly in agreement with theory. These experimental results might support that the electromagnetic waves injected outside of torus plasmas reach to the UHR region and convert wave characteristics to the EBWs for three excitation scenarios.

  11. Mg2Si-Based Materials for the Thermoelectric Energy Conversion

    NASA Astrophysics Data System (ADS)

    Cheng, X.; Farahi, N.; Kleinke, H.

    2016-10-01

    Thermoelectric materials are capable of converting a temperature gradient into electricity (thermoelectric power generation) and vice versa (Peltier cooling). The thermoelectric power generation has been used for decades in spacecraft, where radioactive decay provides the heat source. Additional applications under consideration are based on the utilization of waste heat, for example in automotives or the manufacturing industries. Commercial thermoelectric materials are normally based on Bi2Te3, PbTe, or possibly in the future on the so-called filled skutterudites, such as YbxCo4Sb12. The downside of these materials is that some of their major constituent elements are toxic, namely tellurium, lead, and antimony, and in part rare and expensive (ytterbium, tellurium). Mg2Si on the other hand is composed of abundant, environmentally benign elements, and thus offers a huge advantage for commercial applications. Here, we provide a review of Mg2Si-based materials for thermoelectric energy conversion, discussing how competitive these materials have become in comparison to the above-mentioned more traditional materials.

  12. Accelerator-based conversion (ABC) of weapons plutonium: Plant layout study and related design issues

    SciTech Connect

    Cowell, B.S.; Fontana, M.H.; Krakowski, R.A.; Beard, C.A.; Buksa, J.J.; Davidson, J.W.; Sailor, W.C.; Williamson, M.A.

    1995-04-01

    In preparation for and in support of a detailed R and D Plan for the Accelerator-Based Conversion (ABC) of weapons plutonium, an ABC Plant Layout Study was conducted at the level of a pre-conceptual engineering design. The plant layout is based on an adaptation of the Molten-Salt Breeder Reactor (MSBR) detailed conceptual design that was completed in the early 1070s. Although the ABC Plant Layout Study included the Accelerator Equipment as an essential element, the engineering assessment focused primarily on the Target; Primary System (blanket and all systems containing plutonium-bearing fuel salt); the Heat-Removal System (secondary-coolant-salt and supercritical-steam systems); Chemical Processing; Operation and Maintenance; Containment and Safety; and Instrumentation and Control systems. Although constrained primarily to a reflection of an accelerator-driven (subcritical) variant of MSBR system, unique features and added flexibilities of the ABC suggest improved or alternative approaches to each of the above-listed subsystems; these, along with the key technical issues in need of resolution through a detailed R&D plan for ABC are described on the bases of the ``strawman`` or ``point-of-departure`` plant layout that resulted from this study.

  13. Copper Oxide Thin Films through Solution Based Methods for Electrical Energy Conversion and Storage

    NASA Astrophysics Data System (ADS)

    Zhu, Changqiong

    Copper oxides (Cu2O and CuO), composed of non-toxic and earth abundant elements, are promising materials for electrical energy generation and storage devices. Solution based techniques for creating thin films of these materials, such as electrodeposition, are important to understand and develop because of their potential for realizing substantial energy savings compared to traditional fabrication methods. Cuprous oxide (Cu2O), with its direct band gap, is a p-type semiconductor that is well suited for creating solution-processed photovoltaic devices (solar cells); several key advancements made toward this application are the primary focus of this thesis. Electrodeposition of single-phase, crystalline Cu2O thin films is demonstrated using previously unexplored, acidic lactate/Cu2+ solutions, which has provided additional understanding of the impacts of growth solution chemistry on film formation. The influence of pH on the resulting Cu2O thin film properties is revealed by using the same ligand (sodium lactate) at various solution pH values. Cu2O films grown from acidic lactate solutions can exhibit a distinctive flowerlike, dendritic morphology, in contrast to the faceted, dense films obtained using alkaline lactate solutions. Relative speciation distributions of the various metal complex ions present under different growth conditions are calculated using reported equilibrium association constants and experimentally supported by UV-Visible absorption spectroscopy. Dependence of thin film morphology on the lactate/Cu2+ molar ratio and applied potential is described. Cu2O/eutectic gallium-indium Schottky junction devices are formed and devices are tested under monochromatic green LED illumination. Further surface examination of the Cu2O films using X-ray photoelectron spectroscopy (XPS) reveals the fact that films grown from acidic lactate solution with a small lactate/Cu2+ molar ratio, which exhibit improved photovoltaic performance compared to films grown from

  14. An Evaluation of Shore-Based Radio Direction Finding.

    DTIC Science & Technology

    1978-09-01

    Systems Center (TSC). The evaluation consisted of the following three phases: (1) A preliminary survey to identify and classify available direction...This report describes an evaluation of Radio Direction Finding (RDF) techniques for shore-based position location performed by the Transportation

  15. Direct analysis of ultra-trace semiconductor gas by inductively coupled plasma mass spectrometry coupled with gas to particle conversion-gas exchange technique.

    PubMed

    Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef

    2015-09-03

    An inductively coupled plasma mass spectrometry (ICPMS) coupled with gas to particle conversion-gas exchange technique was applied to the direct analysis of ultra-trace semiconductor gas in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a gas to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a gas exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor gas and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous gas introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl gas in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor gas in air.

  16. A Direct Reading Thermometer Based on a Silicon Diode.

    ERIC Educational Resources Information Center

    Kirkup, L.; Tonthat, C.

    1998-01-01

    Describes a simple circuit based on an inexpensive quad operational amplifier that permits a direct-reading temperature instrument to be constructed using silicon diodes. Encourages the use of this equipment in introductory thermal experiments. (DDR)

  17. A Direct Reading Thermometer Based on a Silicon Diode.

    ERIC Educational Resources Information Center

    Kirkup, L.; Tonthat, C.

    1998-01-01

    Describes a simple circuit based on an inexpensive quad operational amplifier that permits a direct-reading temperature instrument to be constructed using silicon diodes. Encourages the use of this equipment in introductory thermal experiments. (DDR)

  18. Topological computation based on direct magnetic logic communication

    PubMed Central

    Zhang, Shilei; Baker, Alexander A.; Komineas, Stavros; Hesjedal, Thorsten

    2015-01-01

    Non-uniform magnetic domains with non-trivial topology, such as vortices and skyrmions, are proposed as superior state variables for nonvolatile information storage. So far, the possibility of logic operations using topological objects has not been considered. Here, we demonstrate numerically that the topology of the system plays a significant role for its dynamics, using the example of vortex-antivortex pairs in a planar ferromagnetic film. Utilising the dynamical properties and geometrical confinement, direct logic communication between the topological memory carriers is realised. This way, no additional magnetic-to-electrical conversion is required. More importantly, the information carriers can spontaneously travel up to ~300 nm, for which no spin-polarised current is required. The derived logic scheme enables topological spintronics, which can be integrated into large-scale memory and logic networks capable of complex computations. PMID:26508375

  19. Estimating Hardwood Sawmill Conversion Efficiency Based on Sawing Machine and Log.

    Treesearch

    Michael W. Wade; Steven H. Bullard; Philip H. Steele; Philip A. Araman

    1992-01-01

    Increased problems of hardwood timber availability have caused many sawmillers, industry analysts, and planners to recognize the importance of sawmill conversion efficiency. Conversion efficiency not only affects sawmill profits, but is also important on a much broader level. Timber supply issues have caused resource planners and policy makers to consider the effects...

  20. Profiling of Participants in Chat Conversations Using Creativity-Based Heuristics

    ERIC Educational Resources Information Center

    Chiru, Costin-Gabriel; Rebedea, Traian

    2017-01-01

    This article proposes a new fully automated method for identifying creativity that is manifested in a divergent task. The task is represented by chat conversations in small groups, each group having to debate on the same topics, with the purpose of better understanding the discussed concepts. The chat conversations were created by undergraduate…

  1. A Framework of Synthesizing Tutoring Conversation Capability with Web-Based Distance Education Courseware

    ERIC Educational Resources Information Center

    Song, Ki-Sang; Hu, Xiangen; Olney, Andrew; Graesser, Arthur C.

    2004-01-01

    Whereas existing learning environments on the Web lack high level interactivity, we have developed a human tutor-like tutorial conversation system for the Web that enhances educational courseware through mixed-initiative dialog with natural language processing. The conversational tutoring agent is composed of an animated tutor, a Latent Semantic…

  2. Developing Interactional Competence through Video-Based Computer-Mediated Conversations: Beginning Learners of Spanish

    ERIC Educational Resources Information Center

    Tecedor Cabrero, Marta

    2013-01-01

    This dissertation examines the discourse produced by beginning learners of Spanish using social media. Specifically, it looks at the use and development of interactional resources during two video-mediated conversations. Through a combination of Conversation Analysis tools and quantitative data analysis, the use of turn-taking strategies, repair…

  3. Profiling of Participants in Chat Conversations Using Creativity-Based Heuristics

    ERIC Educational Resources Information Center

    Chiru, Costin-Gabriel; Rebedea, Traian

    2017-01-01

    This article proposes a new fully automated method for identifying creativity that is manifested in a divergent task. The task is represented by chat conversations in small groups, each group having to debate on the same topics, with the purpose of better understanding the discussed concepts. The chat conversations were created by undergraduate…

  4. Developing Interactional Competence through Video-Based Computer-Mediated Conversations: Beginning Learners of Spanish

    ERIC Educational Resources Information Center

    Tecedor Cabrero, Marta

    2013-01-01

    This dissertation examines the discourse produced by beginning learners of Spanish using social media. Specifically, it looks at the use and development of interactional resources during two video-mediated conversations. Through a combination of Conversation Analysis tools and quantitative data analysis, the use of turn-taking strategies, repair…

  5. Polyoxometalate-based Catalysts for Toxic Compound Decontamination and Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Guo, Weiwei

    Polyoxometalates (POMs) have been attracting interest from researchers in the fields of Inorganic Chemistry, Physical Chemistry, Biomolecular Chemistry, etc. Their unique structures and properties render them versatile and facilitate applications in medicine, magnetism, electrochemistry, photochemistry and catalysis. In particular, toxic compound (chemical warfare agents (CWAs) and toxic industrial compounds (TICs)) decontamination and solar energy conversion by POM-based materials have becoming promising and important research areas that deserve much attention. The focus of this thesis is to explore the structural features of POMs, to develop POM-based materials and to investigate their applications in toxic compound decontamination and solar energy conversion. The first part of this thesis gives a general introduction on the history, structures, properties and applications of POMs. The second part reports the synthesis, structures, and reactivity of different types of POMs in the destruction of TICs and CWAs. Three tetra-n-butylammonium (TBA) salts of polyvanadotungstates, [n-Bu4N]6[ PW9V3], [n-Bu4N] 5H2PW8V4O40 (PW 8V4), [n-Bu4N]4H 5PW6V6O40· 20H2O (PW6V6) are discussed in detail. These vanadium-substituted Keggin type POMs show effective activity for the aerobic oxidation of formaldehyde (a major TIC and human-environment carcingen) to formic acid under ambient conditions. Moreover, two types of POMs have also been developed for the removal of CWAs and/or their simulants. Specifically, a layered manganese(IV)-containing heteropolyvanadate with a 1:14 Stoichiometry, K4Li2[MnV14O40]˙21H2 O has been prepared. Its catalytic activity for oxidative removal of 2-chloroethyl ethyl sulfide (a mustard simulant) is discussed. The second type of POM developed for decontamination of CWAs and their simulants is the new one-dimensional polymeric polyniobate (P-PONb), K12[Ti 2O2][GeNb12O40]˙19H2O (KGeNb). The complex has been applied to the decontamination of a wide range

  6. Engineering Bacteria for Efficient Fuel Production: Novel Biological Conversion of Hydrogen and Carbon Dioxide Directly into Free Fatty Acids

    SciTech Connect

    2010-07-12

    Electrofuels Project: OPX Biotechnologies is engineering a microorganism currently used in industrial biotechnology to directly produce a liquid fuel from hydrogen and carbon dioxide (CO2). The microorganism has the natural ability to use hydrogen and CO2 for growth. OPX Biotechnologies is modifying the microorganism to divert energy and carbon away from growth and towards the production of liquid fuels in larger, commercially viable quantities. The microbial system will produce a fuel precursor that can be chemically upgraded to various hydrocarbon fuels.

  7. High Photon-to-Current Conversion in Solar Cells Based on Light-Absorbing Silver Bismuth Iodide.

    PubMed

    Zhu, Huimin; Pan, Mingao; Johansson, Malin B; Johansson, Erik M J

    2017-06-22

    Here, a lead-free silver bismuth iodide (AgI/BiI3 ) with a crystal structure with space group R3‾ m is investigated for use in solar cells. Devices based on the silver bismuth iodide deposited from solution on top of TiO2 and the conducting polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole-transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %, which is higher than the performance of previously reported bismuth-halide materials for solar cells. Photocurrent generation is observed between 350 and 700 nm, and the maximum external quantum efficiency is around 45 %. The results are compared to solar cells based on the previously reported material AgBi2 I7 , and we observe a clearly higher performance for the devices with the new silver and bismuth iodides composition and different crystal structure. The X-ray diffraction spectrum of the most efficient silver bismuth iodide material shows a hexagonal crystal structure with space group R3‾ m, and from the light absorption spectrum we obtain an indirect band gap energy of 1.62 eV and a direct band gap energy of 1.85 eV. This report shows the possibility for finding new structures of metal-halides efficient in solar cells and points out new directions for further exploration of lead-free metal-halide solar cells. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  8. Efficient Conversion of Lignin to Electricity Using a Novel Direct Biomass Fuel Cell Mediated by Polyoxometalates at Low Temperatures.

    PubMed

    Zhao, Xuebing; Zhu, J Y

    2016-01-01

    A novel polyoxometalates (POMs) mediated direct biomass fuel cell (DBFC) was used in this study to directly convert lignin to electricity at low temperatures with high power output and Faradaic efficiency. When phosphomolybdic acid H3 PMo12 O40 (PMo12) was used as the electron and proton carrier in the anode solution with a carbon electrode, and O2 was directly used as the final electron acceptor under the catalysis of Pt, the peak power density reached 0.96 mW cm(-2), 560 times higher than that of phenol-fueled microbial fuel cells (MFCs). When the cathode reaction was catalyzed by PMo12, the power density could be greatly enhanced to 5 mW cm(-2). Continuous operation demonstrated that this novel fuel cell was promising as a stable electrochemical power source. Structure analysis of the lignin indicated that the hydroxyl group content was reduced whereas the carbonyl group content increased. Both condensation and depolymerization takes place during the PMo12 oxidation of lignin. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Mode conversion based on the acousto-optical interaction in photonic-phononic waveguide

    NASA Astrophysics Data System (ADS)

    Chen, Guodong; Zhang, Ruiwen; Xiong, Huang; Xie, Heng; Gao, Ya; Feng, Danqi; Sun, Junqiang

    2015-02-01

    We present a scheme for on-chip optical mode conversion in a hybrid photonic-phononic waveguide. Both propagating optical and acoustic wave can be tightly confined in the hybrid waveguide, and the acoustooptical interaction can be enhanced to realize optical mode conversion within a chip-scale size. The theoretical model of the acousto-optic interaction is established to explain the mode conversion. The numerical simulation results indicate that the high efficient mode conversion can be achieved by adjusting the intensity of the acoustic wave. We also show that the mode conversion bandwidth can be dramatically broadened to 13 THz by adjusting the frequency of the acoustic wave to match phase condition of the acousto-optic interaction. This mode converter on-chip is promising in order to increase the capacity of silicon data busses for on-chip optical interconnections.

  10. Conversion from tacrolimus to cyclosporine--a based immunosuppression following liver transplantation.

    PubMed

    Doria, Cataldo; Jain, Ashok Kumar B; Scott, Victor L; Gruttadauria, Salvatore; Marino, Ignazio R; Doyle, Howard R; Fung, John J

    2003-06-01

    We examined the frequency, reasons and outcome after conversion from Tacrolimus to Cyclosporine A. From August 1989 to December 1992, 1000 consecutive liver transplantation patients were studied, which included 834 adults (age>18 yr.) and 166 children with mean follow-up of 77 months (range 56 to 96). A prospectively populated electronic database was queried to identify patients that underwent conversion, the clinical indication and outcomes. Thirty-seven out of 834 adult recipients (4.43%), mean age of 48.4+/-12.9 years, 19 male (51.35%) and 18 females (48.64%) required conversion from Tacrolimus to Cyclosporine A baseline immunosuppressive therapy. No pediatric patient required conversion. The mean time interval from liver transplantation to Cyclosporine A conversion was 443.45+/-441.44 days (range 22 to 1641). The clinical indications for conversion included: 20 neurological (54%), 6 gastrointestinal (16%), 5 hematological (14%), and 6 other (16%) scenarios. Seven of the 37 patients (18.9%) died. The causes of death were multi-organ failure (2), sepsis (2), pancreatitis (1), hepatic failure due to relapse of ethanol abuse (1), and unknown cause (1). Nine out of 37 patients (24.32%) had to be reconverted to Tacrolimus (mean 282.22+/-499.79 days; range 15 to 1583 day with a median of 135) after institution of Cyclosporine A; none showed recurrence of the original symptoms. The reasons for these re-conversions were acute cellular rejection (44%, n=4), chronic rejection (11%, n=1), increased hepatic enzymes (33%, n=3) and progressively worsening neurological symptoms (11%, n=1). The frequency of conversion from Tacrolimus to Cyclosporine A was 4.43%. Conversion is safe and efficacious if done in a controlled setting. Additionally, re-conversion to Tacrolimus for lack of efficacy of Cyclosporine A did not appear to be associated with a recurrence of the condition that caused the initial switch.

  11. Nanostructured hybrid materials based on reduced graphene oxide for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Morais, Andreia; Amaral Carminati, Saulo do; Nogueira, Ana Flavia

    2016-09-01

    Research on carbon-based photocatalytic nanomaterials has been a field in continuous expansion in the last years. Graphene (or its derivatives) is currently one of the most studied materials due to its high surface area, photodegradation resistance, optical transparency and high charge mobility values. All of these excellent properties are highlighted for applications in various research areas. The incorporation of small amounts of reduced graphene oxide (RGO) sheets in semiconductors matrices is also a strategy widely used to improve the physicochemical properties, which cannot normally be achieved using conventional composites or pristine semiconductors. Most studies suggest that these twodimensional (2D) materials can facilitate electron injection and assist the electron transport in semiconductors. In this context, this manuscript will present examples of graphene-based semiconductor nanocomposites obtained by our research group and their application in the photodegradation of methylene blue (MB), photocatalytic conversion of CO2 to hydrocarbon fuels and photocatalytic water splitting reaction. Our results show the positive effect of coupling the RGO sheets with semiconductors for photocatalysis.

  12. Conversion of borate-based glass scaffold to hydroxyapatite in a dilute phosphate solution.

    PubMed

    Liu, Xin; Pan, Haobo; Fu, Hailuo; Fu, Qiang; Rahaman, Mohamed N; Huang, Wenhai

    2010-02-01

    Porous scaffolds of a borate-based glass (composition in mol%: 6Na2O, 8K2O, 8MgO, 22CaO, 36B2O3, 18SiO2, 2P2O5), with interconnected porosity of approximately 70% and pores of size 200-500 microm, were prepared by a polymer foam replication technique. The degradation of the scaffolds and conversion to a hydroxyapatite-type material in a 0.02 M K2HPO4 solution (starting pH = 7.0) at 37 degrees C were studied by measuring the weight loss of the scaffolds, as well as the pH and the boron concentration of the solution. X-ray diffraction, scanning electronic microscopy and energy dispersive x-ray analysis showed that a hydroxyapatite-type material was formed on the glass surface within 7 days of immersion in the phosphate solution. Cellular response to the scaffolds was assessed using murine MLO-A5 cells, an osteogenic cell line. Scanning electron microscopy showed that the scaffolds supported cell attachment and proliferation during the 6 day incubation. The results indicate that this borate-based glass could provide a promising degradable scaffold material for bone tissue engineering applications.

  13. A conversation-based process tracing method for use with naturalistic decisions: an evaluation study.

    PubMed

    Williamson, J; Ranyard, R; Cuthbert, L

    2000-05-01

    This study is an evaluation of a process tracing method developed for naturalistic decisions, in this case a consumer choice task. The method is based on Huber et al.'s (1997) Active Information Search (AIS) technique, but develops it by providing spoken rather than written answers to respondents' questions, and by including think aloud instructions. The technique is used within a conversation-based situation, rather than the respondent thinking aloud 'into an empty space', as is conventionally the case in think aloud techniques. The method results in a concurrent verbal protocol as respondents make their decisions, and a retrospective report in the form of a post-decision summary. The method was found to be virtually non-reactive in relation to think aloud, although the variable of Preliminary Attribute Elicitation showed some evidence of reactivity. This was a methodological evaluation, and as such the data reported are essentially descriptive. Nevertheless, the data obtained indicate that the method is capable of producing information about decision processes which could have theoretical importance in terms of evaluating models of decision-making.

  14. Defect chemistry and defect engineering of TiO2-based semiconductors for solar energy conversion.

    PubMed

    Nowotny, Janusz; Alim, Mohammad Abdul; Bak, Tadeusz; Idris, Mohammad Asri; Ionescu, Mihail; Prince, Kathryn; Sahdan, Mohd Zainizan; Sopian, Kamaruzzaman; Mat Teridi, Mohd Asri; Sigmund, Wolfgang

    2015-12-07

    This tutorial review considers defect chemistry of TiO2 and its solid solutions as well as defect-related properties associated with solar-to-chemical energy conversion, such as Fermi level, bandgap, charge transport and surface active sites. Defect disorder is discussed in terms of defect reactions and the related charge compensation. Defect equilibria are used in derivation of defect diagrams showing the effect of oxygen activity and temperature on the concentration of both ionic and electronic defects. These defect diagrams may be used for imposition of desired semiconducting properties that are needed to maximize the performance of TiO2-based photoelectrodes for the generation of solar hydrogen fuel using photo electrochemical cells (PECs) and photocatalysts for water purification. The performance of the TiO2-based semiconductors is considered in terms of the key performance-related properties (KPPs) that are defect related. It is shown that defect engineering may be applied for optimization of the KPPs in order to achieve optimum performance.

  15. A Depth Map Generation Algorithm Based on Saliency Detection for 2D to 3D Conversion

    NASA Astrophysics Data System (ADS)

    Yang, Yizhong; Hu, Xionglou; Wu, Nengju; Wang, Pengfei; Xu, Dong; Rong, Shen

    2017-09-01

    In recent years, 3D movies attract people's attention more and more because of their immersive stereoscopic experience. However, 3D movies is still insufficient, so estimating depth information for 2D to 3D conversion from a video is more and more important. In this paper, we present a novel algorithm to estimate depth information from a video via scene classification algorithm. In order to obtain perceptually reliable depth information for viewers, the algorithm classifies them into three categories: landscape type, close-up type, linear perspective type firstly. Then we employ a specific algorithm to divide the landscape type image into many blocks, and assign depth value by similar relative height cue with the image. As to the close-up type image, a saliency-based method is adopted to enhance the foreground in the image and the method combine it with the global depth gradient to generate final depth map. By vanishing line detection, the calculated vanishing point which is regarded as the farthest point to the viewer is assigned with deepest depth value. According to the distance between the other points and the vanishing point, the entire image is assigned with corresponding depth value. Finally, depth image-based rendering is employed to generate stereoscopic virtual views after bilateral filter. Experiments show that the proposed algorithm can achieve realistic 3D effects and yield satisfactory results, while the perception scores of anaglyph images lie between 6.8 and 7.8.

  16. Learning through Conversation.

    ERIC Educational Resources Information Center

    Kelly, Patricia R.; Klein, Adria F.; Pinnell, Gay Su

    1996-01-01

    Through teacher-child conversation, experts use oral language to help novices take on more complex tasks; and Reading Recovery children, who are obviously having difficulty with school-based learning, are especially in need of significant conversations with adults. Reading and writing processes are supported through conversation with Reading…

  17. A photoacoustic imaging reconstruction method based on directional total variation with adaptive directivity.

    PubMed

    Wang, Jin; Zhang, Chen; Wang, Yuanyuan

    2017-05-30

    In photoacoustic tomography (PAT), total variation (TV) based iteration algorithm is reported to have a good performance in PAT image reconstruction. However, classical TV based algorithm fails to preserve the edges and texture details of the image because it is not sensitive to the direction of the image. Therefore, it is of great significance to develop a new PAT reconstruction algorithm to effectively solve the drawback of TV. In this paper, a directional total variation with adaptive directivity (DDTV) model-based PAT image reconstruction algorithm, which weightedly sums the image gradients based on the spatially varying directivity pattern of the image is proposed to overcome the shortcomings of TV. The orientation field of the image is adaptively estimated through a gradient-based approach. The image gradients are weighted at every pixel based on both its anisotropic direction and another parameter, which evaluates the estimated orientation field reliability. An efficient algorithm is derived to solve the iteration problem associated with DDTV and possessing directivity of the image adaptively updated for each iteration step. Several texture images with various directivity patterns are chosen as the phantoms for the numerical simulations. The 180-, 90- and 30-view circular scans are conducted. Results obtained show that the DDTV-based PAT reconstructed algorithm outperforms the filtered back-projection method (FBP) and TV algorithms in the quality of reconstructed images with the peak signal-to-noise rations (PSNR) exceeding those of TV and FBP by about 10 and 18 dB, respectively, for all cases. The Shepp-Logan phantom is studied with further discussion of multimode scanning, convergence speed, robustness and universality aspects. In-vitro experiments are performed for both the sparse-view circular scanning and linear scanning. The results further prove the effectiveness of the DDTV, which shows better results than that of the TV with sharper image edges and

  18. Multichannel mode conversion and multiplexing based on a single spatial light modulator for optical communication

    NASA Astrophysics Data System (ADS)

    Nie, Song; Yu, Song; Cai, Shanyong; Lan, Mingying; Gu, Wanyi

    2016-07-01

    A method is proposed to achieve multichannel mode conversion and multiplexing by dividing a single spatial light modulator into several blocks with the mode conversion pattern and blazed grating loaded on each block. The conversion patterns realize the precise excitation of higher order modes using combined amplitude and phase modulation. The blazed gratings bring together incident beams, so these beams can be coupled into few-mode fiber (FMF). In the experiment, four higher order modes are precisely excited and converge with a tilt angle. Through the simulation method, these beams can be coupled into FMF with small tilt angles (0.0344 deg for LP11 mode).

  19. Bioinspired photoelectric conversion system based on carbon-quantum-dot-doped dye-semiconductor complex.

    PubMed

    Ma, Zheng; Zhang, Yong-Lai; Wang, Lei; Ming, Hai; Li, Haitao; Zhang, Xing; Wang, Fang; Liu, Yang; Kang, Zhenhui; Lee, Shuit-Tong

    2013-06-12

    Compared to nature's photoelectric conversion processes, artificial devices are still far inferior in efficiency and stability. Inspired by light absorption and resonance energy transfer processes of chlorophyll, we developed a highly efficient photoelectric conversion system by introducing Carbon quantum dots (CQDs) as an electron transfer intermediary. Compared with conventional dye-sensitized semiconductor systems, the present CQD-doped system showed significantly higher photoelectric conversion efficiency, as much as 7 times that without CQDs. The CQD-doped dye/semiconductor system may provide a powerful approach to the development of highly efficient photoelectric devices.

  20. One shot confocal microscopy based on wavelength/space conversion by use of multichannel spectrometer

    NASA Astrophysics Data System (ADS)

    Miyamoto, Shuji; Hase, Eiji; Ichikawa, Ryuji; Mnamikawa, Takeo; Yasui, Takeshi; Yamamoto, Hirotugu

    2016-03-01

    Confocal laser microscope (CLM) has been widely used in the fields of the non-contact surface topography, biomedical imaging, and other applications, because of two-dimensional (2D) or three-dimensional (3D) imaging capability with the confocal effect and the stray light elimination. Although the conventional CLM has acquired the 2D image by mechanical scanning of the focused beam spot, further reduction of image acquisition time and the robustness to various disturbances are strongly required. To this end, it is essential to omit mechanical scanning for the image acquisition. In this article, we developed the scan-less, full-field CLM by combination of the line-focused CLM with the wavelength/1D-space conversion. This combination enables us to form the 2D focal array of a 2D rainbow beam on a sample and to encode the 2D image information of a sample on the 2D rainbow beam. The image-encoded 2D rainbow beam was decoded as a spectral line image by a multi-channel spectrometer equipped with a CMOS camera without the need for the mechanical scanning. The confocal full-field image was acquired during 0.23 ms with the lateral resolution of 26.3μm and 4.9μm for the horizontal and vertical directions, respectively, and the depth resolution of 34.9μm. We further applied this scan-less, full-field CLM for biomedical imaging of a sliced specimen and non-contact surface topography of an industry products. These demonstrations highlight a high potential of the proposed scan-less, full-field CLM.