Science.gov

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 Astrophysics Data System (ADS)

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

    1989-12-01

    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 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.

  8. 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…

  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. 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.

  11. 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.

  12. Direct somatic lineage conversion.

    PubMed

    Tanabe, Koji; Haag, Daniel; Wernig, Marius

    2015-10-19

    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

  13. 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.

  14. 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.

  15. 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. PMID:25572361

  16. 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.

  17. 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.

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

    DOE PAGESBeta

    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 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Photonic generation of bipolar direct-sequence UWB signals based on optical spectral shaping and incoherent frequency-to-time conversion

    NASA Astrophysics Data System (ADS)

    Mu, Hongqian; Wang, Muguang; Ye, Jun; Jian, Shuisheng

    2016-06-01

    A novel technology to obtain binary phase-coded ultrawideband (UWB) signals for direct-sequence spread-spectrum communication systems is investigated by using a cost-effective incoherent source. The bipolar encoding is performed based on an all-fiber spectrum shaper composed of two FBG arrays to tailor the optical spectrum, and a section of single-mode fiber to achieve incoherent frequency-to-time conversion. We demonstrate a 1.325-Gb/s UWB encoding system by the use of binary spreading codes of 4-chip length via computer simulations. The proposed bipolar UWB encoding technology can be applied to high-speed UWB-over-fiber communication systems.

  5. 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.

  6. 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. PMID:21682296

  7. 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

  8. 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.

  9. 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.

  10. 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…

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

    PubMed

    Sun, Junming; Baylon, Rebecca A L; 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. PMID:26624526

  12. 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.

  13. 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.

  14. 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.

  15. Direct, nonoxidative conversion of methane to ethylene, aromatics, and hydrogen.

    PubMed

    Guo, Xiaoguang; Fang, Guangzong; Li, Gang; Ma, Hao; Fan, Hongjun; Yu, Liang; Ma, Chao; Wu, Xing; Deng, Dehui; Wei, Mingming; Tan, Dali; Si, Rui; Zhang, Shuo; Li, Jianqi; Sun, Litao; Tang, Zichao; Pan, Xiulian; Bao, Xinhe

    2014-05-01

    The efficient use of natural gas will require catalysts that can activate the first C-H bond of methane while suppressing complete dehydrogenation and avoiding overoxidation. We report that single iron sites embedded in a silica matrix enable direct, nonoxidative conversion of methane, exclusively to ethylene and aromatics. The reaction is initiated by catalytic generation of methyl radicals, followed by a series of gas-phase reactions. The absence of adjacent iron sites prevents catalytic C-C coupling, further oligomerization, and hence, coke deposition. At 1363 kelvin, methane conversion reached a maximum at 48.1% and ethylene selectivity peaked at 48.4%, whereas the total hydrocarbon selectivity exceeded 99%, representing an atom-economical transformation process of methane. The lattice-confined single iron sites delivered stable performance, with no deactivation observed during a 60-hour test. PMID:24812398

  16. 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)

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Advancements and future directions in enzyme technology for biomass conversion.

    PubMed

    Zhang, Zisheng; Donaldson, Adam A; Ma, Xiaoxun

    2012-01-01

    Enzymatic hydrolysis of pre-treated lignocellulosic biomass is an ideal alternative to acid hydrolysis for bio-ethanol production, limited primarily by pre-treatment requirements and economic considerations arising from enzyme production costs and specific activities. The quest for cheaper and better enzymes has prompted years of bio-prospecting, strain optimization through genetic engineering, enzyme characterization for simple and complex lignocellulosic feedstock, and the development of pre-treatment strategies to mitigate inhibitory effects. The recent shift to systematic characterizations of de novo mixtures of purified proteins is a promising indicator of maturation within this field of study, facilitating progression towards feedstock assay-based rapid enzyme mixture optimization. It is imperative that international standards be developed to enable meaningful comparisons between these studies and the construction of a database of enzymatic activities and kinetics, aspects of which are explored here-in. Complementary efforts to improve the economic viability of enzymatic hydrolysis through process integration and reactor design are also considered, where membrane-confinement shows significant promise despite the associated technological challenges. Significant advancements in enzyme technology towards the economic conversion of lignocellulosic biomass should be expected within the next few years as systematic research in enzyme activities conforms to that of traditional reaction engineering. PMID:22306162

  2. 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…

  3. 32 CFR Appendix C to Part 169a - Simplified Cost Comparison and Direct Conversion of CAs

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 1 2013-07-01 2013-07-01 false Simplified Cost Comparison and Direct Conversion of CAs C Appendix C to Part 169a National Defense Department of Defense OFFICE OF THE SECRETARY OF... 169a—Simplified Cost Comparison and Direct Conversion of CAs A. This appendix provides guidance...

  4. 32 CFR Appendix C to Part 169a - Simplified Cost Comparison and Direct Conversion of CAs

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 1 2012-07-01 2012-07-01 false Simplified Cost Comparison and Direct Conversion of CAs C Appendix C to Part 169a National Defense Department of Defense OFFICE OF THE SECRETARY OF... 169a—Simplified Cost Comparison and Direct Conversion of CAs A. This appendix provides guidance...

  5. 32 CFR Appendix C to Part 169a - Simplified Cost Comparison and Direct Conversion of CAs

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 1 2011-07-01 2011-07-01 false Simplified Cost Comparison and Direct Conversion of CAs C Appendix C to Part 169a National Defense Department of Defense OFFICE OF THE SECRETARY OF... 169a—Simplified Cost Comparison and Direct Conversion of CAs A. This appendix provides guidance...

  6. 32 CFR Appendix C to Part 169a - Simplified Cost Comparison and Direct Conversion of CAs

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 false Simplified Cost Comparison and Direct Conversion of CAs C Appendix C to Part 169a National Defense Department of Defense OFFICE OF THE SECRETARY OF... 169a—Simplified Cost Comparison and Direct Conversion of CAs A. This appendix provides guidance...

  7. 32 CFR Appendix C to Part 169a - Simplified Cost Comparison and Direct Conversion of CAs

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 1 2014-07-01 2014-07-01 false Simplified Cost Comparison and Direct Conversion of CAs C Appendix C to Part 169a National Defense Department of Defense OFFICE OF THE SECRETARY OF... 169a—Simplified Cost Comparison and Direct Conversion of CAs A. This appendix provides guidance...

  8. 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,…

  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

    2016-08-01

    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. PMID:27493179

  11. 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.

  12. 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.

  13. 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. PMID:23901504

  14. 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.

  15. 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

  16. Characterization of on-site digital mammography systems: Direct versus indirect conversion detectors

    NASA Astrophysics Data System (ADS)

    Youn, Hanbean; Han, Jong Chul; Yun, Seungman; Kam, Soohwa; Cho, Seungryong; Kim, Ho Kyung

    2015-06-01

    We investigated the performances of two digital mammography systems. The systems use a cesium-iodide (CsI) scintillator and an amorphous selenium ( a-Se) photoconductor for X-ray detection and are installed in the same hospital. As physical metrics, we measured the modulationtransfer function (MTF), the noise-power spectrum (NPS), and the detective quantum efficiency (DQE). In addition, we analyzed the contrast-detail performances of the two systems by using a commercial contrast-detail phantom. The CsI-based indirect conversion detector provided better MTF and DQE performances than the a-Se-based direct conversion detector whereas the former provided a poorer NPS performance than the latter. These results are explained by the fact that the CsI-based detector used an MTF restoration preprocessing algorithm. The a-Se-based detector showed better contrast-detail performance than the CsI-based detector. We believe that the highfrequency noise characteristic of a detector is more responsible for the visibility of small details than its spatial-resolution performance.

  17. 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. PMID:18252585

  18. 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.

  19. 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. PMID:26797488

  20. DIRECT THERMOCHEMICAL CONVERSION OF SEWAGE SLUDGE TO FUEL OIL

    EPA Science Inventory

    A disposal method for primary sewage sludge and industrial sludges which generates boiler fuel as a product and is energy self sufficient or energy-generating is described. The method involves direct liquefaction in a mild aqueous alkali above 250 degs. C and was demonstrated for...

  1. 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

  2. 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)

  3. Direct biological conversion of electrical current into methane by electromethanogenesis.

    PubMed

    Cheng, Shaoan; Xing, Defeng; Call, Douglas F; Logan, Bruce E

    2009-05-15

    New sustainable methods are needed to produce renewable energy carriers that can be stored and used for transportation, heating, or chemical production. Here we demonstrate that methane can directly be produced using a biocathode containing methanogens in electrochemical systems (abiotic anode) or microbial electrolysis cells (MECs; biotic anode) by a process called electromethanogenesis. At a set potential of less than -0.7 V (vs Ag/AgCl), carbon dioxide was reduced to methane using a two-chamber electrochemical reactor containing an abiotic anode, a biocathode, and no precious metal catalysts. At -1.0 V, the current capture efficiency was 96%. Electrochemical measurements made using linear sweep voltammetry showed that the biocathode substantially increased current densities compared to a plain carbon cathode where only small amounts of hydrogen gas could be produced. Both increased current densities and very small hydrogen production rates by a plain cathode therefore support a mechanism of methane production directly from current and not from hydrogen gas. The biocathode was dominated by a single Archaeon, Methanobacterium palustre. When a current was generated by an exoelectrogenic biofilm on the anode growing on acetate in a single-chamber MEC, methane was produced at an overall energy efficiency of 80% (electrical energy and substrate heat of combustion). These results show that electromethanogenesis can be used to convert electrical current produced from renewable energy sources (such as wind, solar, or biomass) into a biofuel (methane) as well as serving as a method for the capture of carbon dioxide. PMID:19544913

  4. Direct conversion of human fibroblasts to induced serotonergic neurons.

    PubMed

    Xu, Z; Jiang, H; Zhong, P; Yan, Z; Chen, S; Feng, J

    2016-01-01

    Serotonergic (5HT) neurons exert diverse and widespread functions in the brain. Dysfunction of the serotonergic system gives rise to a variety of mental illnesses including depression, anxiety, obsessive compulsive disorder, autism and eating disorders. Here we show that human primary fibroblasts were directly converted to induced serotonergic (i5HT) neurons by the expression of Ascl1, Foxa2, Lmx1b and FEV. The transdifferentiation was enhanced by p53 knockdown and appropriate culture conditions including hypoxia. The i5HT neurons expressed markers for mature serotonergic neurons, had Ca(2+)-dependent 5HT release and selective 5HT uptake, exhibited spontaneous action potentials and spontaneous excitatory postsynaptic currents. Application of serotonin significantly increased the firing rate of spontaneous action potentials, demonstrating the functional utility of i5HT neurons for studying serotonergic neurotransmission. The availability of human i5HT neurons will be very useful for research and drug discovery on many serotonin-related mental disorders. PMID:26216300

  5. New bimetallic EMF cell shows promise in direct energy conversion

    NASA Technical Reports Server (NTRS)

    Hesson, J. C.; Shimotake, H.

    1968-01-01

    Concentration cell, based upon a thermally regenerative cell principle, produces electrical energy from any large heat source. This experimental bimetallic EMF cell uses a sodium-bismuth alloy cathode and a pure liquid sodium anode. The cell exhibits reliability, corrosion resistance, and high current density performance.

  6. 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

  7. 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.

  8. 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.

  9. 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. J Biomed Mater Res Part B: Appl Biomater, 104B: 686-697, 2016. PMID:26729213

  10. 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

  11. 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

    2015-12-01

    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

  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. A Competency Based Curriculum Guide: Ethanol Spark Ignition Engine Conversion.

    ERIC Educational Resources Information Center

    Blair, Brittain A.

    This guide is a competency-based vocational curriculum designed to provide educators with viable ethanol (100 percent alcohol) engine conversion procedures stated in simple terms and set in a flexible educational environment. The curriculum is designed so that educators can form various combinations of instructional activities and resource…

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

    DOEpatents

    Terwilliger, Steve

    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. Thermally induced solid-solid structural transition of copper nanoparticles through direct geometrical conversion

    NASA Astrophysics Data System (ADS)

    Cheng, Bingqing; Ngan, Alfonso H. W.

    2013-04-01

    Molecular dynamics simulations of small Cu nanoparticles using three different interatomic potentials at rising temperature indicate that small nanoparticles can undergo solid-solid structural transitions through a direct geometrical conversion route. The direct geometrical conversion can happen for cuboctahedral nanoparticles, which turn into an icosahedra shape: one diagonal of the square faces contracts, and the faces are folded along the diagonal to give rise to two equilateral triangles. The transition is a kinetic process that cannot be fully explained through an energetic point of view. It has low activation energy and fast reaction time in the simulations. The transition mechanism is via the transmission of shear waves initiated from the particle surface and does not involve dislocation activity.

  16. 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.

  17. Thermally induced solid-solid structural transition of copper nanoparticles through direct geometrical conversion.

    PubMed

    Cheng, Bingqing; Ngan, Alfonso H W

    2013-04-28

    Molecular dynamics simulations of small Cu nanoparticles using three different interatomic potentials at rising temperature indicate that small nanoparticles can undergo solid-solid structural transitions through a direct geometrical conversion route. The direct geometrical conversion can happen for cuboctahedral nanoparticles, which turn into an icosahedra shape: one diagonal of the square faces contracts, and the faces are folded along the diagonal to give rise to two equilateral triangles. The transition is a kinetic process that cannot be fully explained through an energetic point of view. It has low activation energy and fast reaction time in the simulations. The transition mechanism is via the transmission of shear waves initiated from the particle surface and does not involve dislocation activity. PMID:23635145

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  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. 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.

  4. Direct conversion of spent fuel to High-Level-Waste (HLW) glass

    SciTech Connect

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

    1994-09-20

    The Glass Material Oxidation and Dissolution System (GMODS) is a recently invented process for the direct, single-step conversion of spent nuclear fuel (SNF) to high-level waste (HLW) glass. GMODS converts metals, ceramics, organics, and amorphous solids to glass in a single step. Conventional vitrification technology can not accept feeds containing metals or carbon. The GMODS has the potential to solve several issues associated with the disposal of various US Department of Energy (DOE) miscellaneous SNFs: (1) chemical forms unacceptable for repository disposal; (2) high cost of qualifying small quantities of particular SNFs for disposal; (3) limitations imposed by high-enriched SNF in a repository because of criticality and safeguards issues; and (4) classified design information. Conversion of such SNFs to glass eliminates these concerns. A description of the GMODS, {open_quotes}strawman{close_quotes} product criteria, experimental work to date, and product characteristics are included herein.

  5. Direct chemical conversion of graphene to boron- and nitrogen- and carbon-containing atomic layers

    NASA Astrophysics Data System (ADS)

    Gong, Yongji; Shi, Gang; Zhang, Zhuhua; Zhou, Wu; Jung, Jeil; Gao, Weilu; Ma, Lulu; Yang, Yang; Yang, Shubin; You, Ge; Vajtai, Robert; Xu, Qianfan; MacDonald, Allan H.; Yakobson, Boris I.; Lou, Jun; Liu, Zheng; Ajayan, Pulickel M.

    2014-01-01

    Graphene and hexagonal boron nitride are typical conductor and insulator, respectively, while their hybrids hexagonal boron carbonitride are promising as a semiconductor. Here we demonstrate a direct chemical conversion reaction, which systematically converts the hexagonal carbon lattice of graphene to boron nitride, making it possible to produce uniform boron nitride and boron carbonitride structures without disrupting the structural integrity of the original graphene templates. We synthesize high-quality atomic layer films with boron-, nitrogen- and carbon-containing atomic layers with full range of compositions. Using this approach, the electrical resistance, carrier mobilities and bandgaps of these atomic layers can be tuned from conductor to semiconductor to insulator. Combining this technique with lithography, local conversion could be realized at the nanometre scale, enabling the fabrication of in-plane atomic layer structures consisting of graphene, boron nitride and boron carbonitride. This is a step towards scalable synthesis of atomically thin two-dimensional integrated circuits.

  6. Wavelength-based analog-to-digital conversion

    NASA Astrophysics Data System (ADS)

    Zmuda, Henry; Hayduk, Michael J.; Bussjager, Rebecca J.; Toughlian, Edward N.

    2002-01-01

    This paper provides a comprehensive understanding of a tunable wavelength-based photonic high-speed analog-to- digital converter (ADC) approach and its anticipated performance. Analytic models, experimental data, and simulation results will provide the fundamental limits on the expected conversion speed and bit resolution. A thorough in situ study of the photonic signal conversion system under simulated space radiation conditions is required to precisely determine its performance in either a natural or man-made space environment. Although this study has not yet been performed on the entire system, preliminary performance predictions will be made based on previously published studies on the individual components within the system. The photonic components of particular interest that will be discussed in the context of radiation hardness includes the edge emitting laser diode with a MQW tuning element, the processor filters, the delay equalizers and the photodetectors.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  8. 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

  9. 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. PMID:27264182

  10. 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

  11. Direct conversion of plutonium-containing materials to borosilicate glass for storage or disposal

    SciTech Connect

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

    1995-06-27

    A new process, the Glass Material Oxidation and Dissolution System (GMODS), has been invented for the direct conversion of plutonium metal, scrap, and residue into borosilicate glass. The glass should be acceptable for either the long-term storage or disposition of plutonium. Conversion of plutonium from complex chemical mixtures and variable geometries into homogeneous glass (1) simplifies safeguards and security; (2) creates a stable chemical form that meets health, safety, and environmental concerns; (3) provides an easy storage form; (4) may lower storage costs; and (5) allows for future disposition options. In the GMODS process, mixtures of metals, ceramics, organics, and amorphous solids containing plutonium are fed directly into a glass melter where they are directly converted to glass. Conventional glass melters can accept materials only in oxide form; thus, it is its ability to accept materials in multiple chemical forms that makes GMODS a unique glass making process. Initial proof-of-principle experiments have converted cerium (plutonium surrogate), uranium, stainless steel, aluminum, and other materials to glass. Significant technical uncertainties remain because of the early nature of process development.

  12. 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.

  13. Porphyrin-Based Supramolecular Nanoarchitectures for Solar Energy Conversion.

    PubMed

    Hasobe, Taku

    2013-06-01

    Photofunctional molecular architectures with well-defined shapes and sizes are of great interest because of various applications such as photovoltaics, photocatalysis, and electronics. Porphyrins are promising building blocks for organized nanoscale superstructures, which perform many of the essential light-harvesting and photoinduced electron/energy transfer reaction. In this Perspective, we present the recent advances in supramolecular architectures of porphyrins for solar energy conversion. First, we state preparation and light energy conversion properties of porphyrin (donor: D) and fullerene (acceptor: A)-based composite spherical nanoassemblies. The interfacial control of D/A molecules based on our supramolecular strategy successfully demonstrates the drastic enhancement of light energy conversion properties as compared to the corresponding nonorganized systems. Then, bar-shaped structures composed of two different D and A molecules with separated inside and outside layers are discussed. This unusual rod formation shows a possibility for a novel zeolite-like photoreaction cavity with efficient visible light absorption. Finally, photophysical and phoelectrochemical properties of supramolecular composites between porphyrins and carbon naotubes/graphenes are briefly described. PMID:26283108

  14. Metal-Free Chemoselective Oxidative Dehomologation or Direct Oxidation of Alcohols: Implication for Biomass Conversion.

    PubMed

    Kim, Sun Min; Shin, Hun Yi; Kim, Dong Wan; Yang, Jung Woon

    2016-02-01

    A transition metal-free, chemoselective reaction was performed using the sodium tert-butoxide-oxygen (NaO(t) Bu-O2 ) system, resulting in either oxidative dehomologation or direct oxidation of alcohols. In particular, the newly developed protocol may be used to predict the major product formed, which depends on alkyl chain length of the alcohols and reaction conditions. The rational mechanism of this transformation was also demonstrated by performing an (18) O isotopic labelling experiment. This protocol presents a straightforward method for biomass conversion of a lignin model compound to phenol and benzoic acid. PMID:26682633

  15. 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.

  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. PMID:25555663

  17. Red long-lasting phosphorescence based on color conversion process

    NASA Astrophysics Data System (ADS)

    Li, Zhanjun; Zhang, Hongwu; Fu, Haixia

    2013-01-01

    The principle of color conversion process was used to generate red long-lasting phosphorescence (LLP) using SrAl2O4:Eu, Dy (SAO) as primary light source and rhodamine B encapsulated mesoporous silica nanoparticles (MCM-R) as effective color conversion agent. The phosphorescence spectra of MCM-R/SAO hybrid samples show green peaks from 425 nm to 550 nm and red peaks from 550 nm to 700 nm, which can be attributed to the phosphorescence of SAO and the fluorescence of MCM-R, respectively. The phosphorescence color can be adjusted from green to red by changing the mass ratio of MCM-R/SAO. When the mass ratio of MCM-R/SAO increases from 0.05 to 1.5, a blue shift for the green peak and a red shift for the red peak of the phosphorescence spectra can be observed and the intensity of the red emission peak increase relatively towards the green one. The phosphorescence decay curves show that MCM-R and SAO have similar decay dynamics and the MCM-R can inherit the LLP properties of SAO. The phosphorescence decay spectra indicate that the MCM-R/SAO hybrid can retain constant and steady visual phosphorescence color. The red phosphorescence can be seen in the dark with naked eyes for more than 5 h. So, the red LLP can be successfully achieved based on the principle of color conversion process.

  18. Direct Conversion of Fibroblasts into Functional Astrocytes by Defined Transcription Factors

    PubMed Central

    Caiazzo, Massimiliano; Giannelli, Serena; Valente, Pierluigi; Lignani, Gabriele; Carissimo, Annamaria; Sessa, Alessandro; Colasante, Gaia; Bartolomeo, Rosa; Massimino, Luca; Ferroni, Stefano; Settembre, Carmine; Benfenati, Fabio; Broccoli, Vania

    2014-01-01

    Summary Direct cell reprogramming enables direct conversion of fibroblasts into functional neurons and oligodendrocytes using a minimal set of cell-lineage-specific transcription factors. This approach is rapid and simple, generating the cell types of interest in one step. However, it remains unknown whether this technology can be applied to convert fibroblasts into astrocytes, the third neural lineage. Astrocytes play crucial roles in neuronal homeostasis, and their dysfunctions contribute to the origin and progression of multiple human diseases. Herein, we carried out a screening using several transcription factors involved in defining the astroglial cell fate and identified NFIA, NFIB, and SOX9 to be sufficient to convert with high efficiency embryonic and postnatal mouse fibroblasts into astrocytes (iAstrocytes). We proved both by gene-expression profiling and functional tests that iAstrocytes are comparable to native brain astrocytes. This protocol can be then employed to generate functional iAstrocytes for a wide range of experimental applications. PMID:25556566

  19. Direct Conversion of Normal and Alzheimer's Disease Human Fibroblasts into Neuronal Cells by Small Molecules.

    PubMed

    Hu, Wenxiang; Qiu, Binlong; Guan, Wuqiang; Wang, Qinying; Wang, Min; Li, Wei; Gao, Longfei; Shen, Lu; Huang, Yin; Xie, Gangcai; Zhao, Hanzhi; Jin, Ying; Tang, Beisha; Yu, Yongchun; Zhao, Jian; Pei, Gang

    2015-08-01

    Neuronal conversion from human fibroblasts can be induced by lineage-specific transcription factors; however, the introduction of ectopic genes limits the therapeutic applications of such induced neurons (iNs). Here, we report that human fibroblasts can be directly converted into neuronal cells by a chemical cocktail of seven small molecules, bypassing a neural progenitor stage. These human chemical-induced neuronal cells (hciNs) resembled hiPSC-derived neurons and human iNs (hiNs) with respect to morphology, gene expression profiles, and electrophysiological properties. This approach was further applied to generate hciNs from familial Alzheimer's disease patients. Taken together, our transgene-free and chemical-only approach for direct reprogramming of human fibroblasts into neurons provides an alternative strategy for modeling neurological diseases and for regenerative medicine. PMID:26253202

  20. 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.

  1. 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.

  2. 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.

  3. 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

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

    PubMed

    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

  5. Accelerator-based conversion (ABC) of reactor and weapons plutonium

    SciTech Connect

    Jensen, R.J.; Trapp, T.J.; Arthur, E.D.; Bowman, C.D.; Davidson, J.W.; Linford, R.K.

    1993-06-01

    An accelerator-based conversion (ABC) system is presented that is capable of rapidly burning plutonium in a low-inventory sub-critical system. The system also returns fission power to the grid and transmutes troublesome long-lived fission products to short lived or stable products. Higher actinides are totally fissioned. The system is suited not only to controlled, rapid burning of excess weapons plutonium, but to the long range application of eliminating or drastically reducing the world total inventory of plutonium. Deployment of the system will require the successful resolution of a broad range of technical issues introduced in the paper.

  6. HMM-Based Voice Conversion Using Quantized F0 Context

    NASA Astrophysics Data System (ADS)

    Nose, Takashi; Ota, Yuhei; Kobayashi, Takao

    We propose a segment-based voice conversion technique using hidden Markov model (HMM)-based speech synthesis with nonparallel training data. In the proposed technique, the phoneme information with durations and a quantized F0 contour are extracted from the input speech of a source speaker, and are transmitted to a synthesis part. In the synthesis part, the quantized F0 symbols are used as prosodic context. A phonetically and prosodically context-dependent label sequence is generated from the transmitted phoneme and the F0 symbols. Then, converted speech is generated from the label sequence with durations using the target speaker's pre-trained context-dependent HMMs. In the model training, the models of the source and target speakers can be trained separately, hence there is no need to prepare parallel speech data of the source and target speakers. Objective and subjective experimental results show that the segment-based voice conversion with phonetic and prosodic contexts works effectively even if the parallel speech data is not available.

  7. 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.

  8. Conversion efficiency of skutterudite-based thermoelectric modules.

    PubMed

    Salvador, James R; Cho, Jung Y; Ye, Zuxin; Moczygemba, Joshua E; Thompson, Alan J; Sharp, Jeffrey W; Koenig, Jan D; Maloney, Ryan; Thompson, Travis; Sakamoto, Jeffrey; Wang, Hsin; Wereszczak, Andrew A

    2014-06-28

    Presently, the only commercially available power generating thermoelectric (TE) modules are based on bismuth telluride (Bi2Te3) alloys and are limited to a hot side temperature of 250 °C due to the melting point of the solder interconnects and/or generally poor power generation performance above this point. For the purposes of demonstrating a TE generator or TEG with higher temperature capability, we selected skutterudite based materials to carry forward with module fabrication because these materials have adequate TE performance and are mechanically robust. We have previously reported the electrical power output for a 32 couple skutterudite TE module, a module that is type identical to ones used in a high temperature capable TEG prototype. The purpose of this previous work was to establish the expected power output of the modules as a function of varying hot and cold side temperatures. Recent upgrades to the TE module measurement system built at the Fraunhofer Institute for Physical Measurement Techniques allow for the assessment of not only the power output, as previously described, but also the thermal to electrical energy conversion efficiency. Here we report the power output and conversion efficiency of a 32 couple, high temperature skutterudite module at varying applied loading pressures and with different interface materials between the module and the heat source and sink of the test system. We demonstrate a 7% conversion efficiency at the module level when a temperature difference of 460 °C is established. Extrapolated values indicate that 7.5% is achievable when proper thermal interfaces and loading pressures are used. PMID:24830880

  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

    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

  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

    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

  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. 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.

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

    DOE PAGESBeta

    Petit, Elsa; Coppi, Maddalena V.; Hayes, James C.; Tolonen, Andrew C.; Warnick, Thomas; Latouf, William G.; Amisano, Danielle; Biddle, Amy; Mukherjee, Supratim; Ivanova, Natalia; et al

    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

  16. 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.

  17. 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. PMID:23819974

  18. 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

  19. 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.

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

    PubMed

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

    2015-08-01

    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. PMID:25856797

  1. 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. PMID:27071683

  2. 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.

  3. 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.

  4. 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. PMID:14753341

  5. A green approach to ethyl acetate: quantitative conversion of ethanol through direct dehydrogenation in a Pd-Ag membrane reactor.

    PubMed

    Zeng, Gaofeng; Chen, Tao; He, Lipeng; Pinnau, Ingo; Lai, Zhiping; Huang, Kuo-Wei

    2012-12-01

    Pincers do the trick: The conversion of ethanol to ethyl acetate and hydrogen was achieved using a pincer-Ru catalyst in a Pd-Ag membrane reactor. Near quantitative conversions and yields could be achieved without the need for acid or base promoters or hydrogen acceptors (see scheme). PMID:23136053

  6. 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

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

    PubMed

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

    2016-05-19

    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. PMID:27153470

  8. 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.

  9. 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. PMID:26601241

  10. 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.

  11. 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. PMID:25680177

  12. 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). PMID:23152147

  13. 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 .

  14. Instant conversion of air to a clathrate hydrate: CO(2) hydrates directly from moist air and moist CO(2)(g).

    PubMed

    Devlin, J Paul; Monreal, I Abrrey

    2010-12-23

    The rapid conversion of vapor mixtures containing the gases CO(2), H(2)S, and HCN to clathrate hydrates was reported recently. The novel method is based on the pulsing of warm vapor mixtures, including a carrier gas, into a cold condensation chamber. With cooling, the vapors, which also include ∼1% water and either tetrahydrofuran or trimethylene oxide as a catalyst, nucleate aqueous solution nanodroplets that, on a millisecond time scale, crystallize as hydrate nanoparticles that consume 100% of the water. Humid air approximates the content of mixtures used successfully in the vapor-to-hydrate conversions. FTIR spectra are examined for gas hydrates formed directly from air and air enriched with CO(2), as well as hydrate particles for which CO(2)(g) serves as both guest and aerosol medium. In each instance all of the water in the condensed phase converts to a clathrate hydrate. The subsecond ether-catalyzed formation of the hydrates near 230 K requires only a few percent of the CO(2) pressure used in conventional processes that yield fractional amounts of gas hydrates on an hour time scale in the same temperature range. PMID:21105676

  15. 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

  16. Small molecule-driven direct conversion of human pluripotent stem cells into functional osteoblasts.

    PubMed

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

    2016-08-01

    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

  17. 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.

  18. 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

  19. 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.

  20. 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

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

    SciTech Connect

    Warren, B.K.; Campbell, K.D.; Matherne, J.L.

    1990-02-14

    Research on promoted metal oxide catalysts has continued with the study of alkaline earth/metal oxide halide catalysts. A barium bromide/alumina catalyst was comparable in methane conversion and selectivity to C{sub 2}'s to barium chloride/alumina catalysts. The effects of varying methane to oxygen feed ratios were explored for one of the best alkaline earth catalysts and one of the best literature catalysts (Li/MgO). A significant decrease in the selectivity to C{sub 2}'s is observed upon addition of ethane to the feed gas (feed gas methane/ethane ratio of 3). This observation demonstrates that a significant amount of ethane should not be recycled during methane oxidation over these types of catalysts under process conditions used. Methane oxidation over barium carbonate alone results in high enough selectivities and methane conversions to suggest an oxidized barium species may be responsible for methane oxidation on barium/metal oxide catalysts. Methane coupling studies have continued using layered perovskite catalysts in the cofeed mode and double perovskite catalysts in the sequential mode. Addition of sodium to the double perovskite LaCaMnCoO{sub 6} resulted in a catalyst with improved selectivity over the one without sodium. A reactor system containing two reactors in under construction. These reactors will be used to study different feed diluents, including steam. One reactor will be used to study the effects of pressure on the reaction. Process economics were explored for a hypothetical methane coupling scheme employing a feed mixture of 7/2/1 nitrogen/methane/oxygen. Economic evaluations of the first two of a series of cases based on extrapolations of Union Carbide methane coupling results have been completed. 33 refs., 17 figs., 2 tabs.

  2. 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

  3. 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. PMID:22445768

  4. 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.

  5. 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. PMID:25765311

  6. Comparative of nuclear technology and direct energy conversion methods for space power systems. Master`s thesis

    SciTech Connect

    Reason, J.P.

    1997-06-01

    The objectives of this thesis are to investigate the theory of direct energy conversion, research the development of space nuclear power systems, evaluate the status of current systems, and draw conclusions about the feasibility and merit of using nuclear power for future space missions. Development of the earliest systems began in 1955 with the Systems for Nuclear Auxiliary Power (SNAP) Program and Project Rover. A detailed review of system design and performance is provided for the reactors and radioisotope thermoelectric generators (RTG`s) of past and current programs. Thermoelectric and thermionic energy conversion techniques have been used predominantly in space nuclear power systems. The theory of these direct energy conversion methods is analyzed. Also, the safety review procedures and regulations governing the launch of nuclear sources into space are characterized. Conclusions compare accomplished levels of system performance to theoretically predicted limits and comment on the usefulness of space nuclear power for space applications.

  7. 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

    2007-06-01

    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. PMID:17627319

  8. 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.

  9. 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...

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

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 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...

  11. 5 CFR 892.303 - Can I pay my premiums directly by check under the premium conversion plan?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 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...

  12. 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...

  13. 5 CFR 892.303 - Can I pay my premiums directly by check under the premium conversion plan?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 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...

  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. PMID:26775089

  15. 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. PMID:22342037

  16. 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. PMID:25283435

  17. Investigation of Properties of As x Se1- x Thin Films for Direct Conversion

    NASA Astrophysics Data System (ADS)

    Bharathan, P.

    2015-08-01

    The electrical characteristics of metal/As x Se1- x /metal structures for potential use in direct-conversion x-ray detectors and imaging applications are reported. The structures exhibit current rectification in both solid (amorphous, crystalline) and liquid As x Se1- x phases. Capacitance-voltage measurements of the device in the amorphous phase find that the capacitance is essentially independent of bias. Transport phenomenon in the amorphous phase of the film was found to be influenced by trapping and the space-charge effect. In the liquid and crystalline phases, transport in the devices was characteristic of thermionic emission. The indium tin oxide (ITO)/a-As0.01Se0.99/Au 2.85- μm-thick device gave a short-circuit current ( I sc) of 0.16 μA, an open-circuit voltage ( V oc) of 0.1 V, and a fill factor of 0.29 at 384 K under irradiation from visible light. An interpretation of the current-voltage characteristics in the amorphous phase has been made using the self-consistent drift-diffusion model of transport, and material parameters of a-As x Se1- x films have been extracted by fitting the experimentally measured I- V data. The model indicated that transport in the ITO/a-As0.01Se0.99/Au film was dominated by shallow-level traps with density of 5 × 1015 cm-3 at depth of 0.3 eV from the band edge. The photoconversion efficiency was found to be limited by low photogeneration efficiency, high amount of recombination losses, and the level of charge injection in the a-As x Se1- x films.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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…

  4. Direct Conversion of Aldehydes and Ketones to Allylic Halides by a NbX5-[3,3] Rearrangement

    PubMed Central

    Fleming, Fraser F.; Ravikumar, P. C.; Yao, Lihua

    2009-01-01

    Sequential addition of vinylmagnesium bromide and NbCl5, or NbBr5, to a series of aldehydes and ketones directly provides homologated, allylic halides. Transposition of the intermediate vinyl alkoxide is envisaged through a metalla-halo-[3,3] rearrangement with concomitant delivery of the halogen to the terminal carbon. The [3,3] rearrangement is equally effective for the conversion of a propargyllic alcohol to the corresponding allenyl bromide. PMID:20046989

  5. 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. PMID:24989459

  6. 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.

  7. 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

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

    PubMed

    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

  9. 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

  10. Light-triggered thermoelectric conversion based on a carbon nanotube-polymer hybrid gel.

    PubMed

    Miyako, Eijiro; Nagata, Hideya; Funahashi, Ryoji; Hirano, Ken; Hirotsu, Takahiro

    2009-01-01

    Lights? Nanotubes? Action! A hydrogel comprising lysozymes, poly(ethylene glycol), phospholipids, and functionalized single-walled carbon nanotubes is employed for light-driven thermoelectric conversion. A photoinduced thermoelectric conversion module based on the hydrogel functions as a novel electric power generator (see image). This concept may find application in various industries, such as robotics and aerospace engineering. PMID:19455558

  11. 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...

  12. 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...

  13. 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...

  14. 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.

  15. Enhanced light absorption in thin-film solar cells with light propagation direction conversion.

    PubMed

    Suemune, Ikuo

    2013-05-01

    Enhancement of optical absorption in thin-film solar cells (TF-SCs) has been the long-lasting issue to achieve high efficiencies. Grating couplers have been studied for the conversion of incident light into guided modes propagating along TF-SCs to extend optical path for higher optical absorption. However the wavelength band for the efficient conversion remained relatively narrow and the overall improvement of TF-SC efficiencies has been limited. This paper demonstrates that the grating height design as well as the phase matching condition is important for the enhancement of optical absorption in TF-SCs with the calculation of short-circuit currents as a figure of merit for optimization. The influence of the light absorption coefficients and grating coupling strengths on the light absorption bandwidth is also discussed. PMID:24104442

  16. 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.

  17. 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

  18. 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.

  19. Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes.

    PubMed

    Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

    2016-06-29

    Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal-semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation. PMID:27168177

  20. Hot-electron-based solar energy conversion with metal–semiconductor nanodiodes

    NASA Astrophysics Data System (ADS)

    Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

    2016-06-01

    Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal–semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation.

  1. 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.

  2. 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. PMID:25766123

  3. Enhanced direct conversion of fibroblasts into hepatocyte-like cells by Kdm2b.

    PubMed

    Zakikhan, Kobra; Pournasr, Behshad; Nassiri-Asl, Marjan; Baharvand, Hossein

    2016-05-20

    Cell fate conversion of terminally differentiated cells by defined transcription factors between different lineages is a new approach to produce new cells that have the capability to repair or replace diseased and damaged tissues. Previous studies have demonstrated that this inefficient process can be facilitated by the inclusion of additional factors. Here we report that Kdm2b, a histone demethylase, has the capability to promote conversion of fibroblasts to functional induced hepatocyte-like (iHep) cells in combination with previously reported hepatic lineage transcription factors, Hnf4α and Foxa3. This approach led to increased numbers of epithelial-like colonies, hepatic markers and functionality which included periodic acid-Schiff (PAS) positive colonies, CYP450 activity, low-density lipoprotein and indocyanine green (ICG) uptake, as well as Albumin secretion. Additionally, the transplanted iHep cells were engraftable, expressed Albumin, and contributed to the recovery of a carbon tetrachloride-injured mouse model. These results have not only identified an important epigenetic factor for iHep generation, but also brought new insight into the molecular nature of hepatogenesis and future biomedical applications for liver diseases. PMID:27103435

  4. Trail formation based on directed pheromone deposition.

    PubMed

    Boissard, Emmanuel; Degond, Pierre; Motsch, Sebastien

    2013-05-01

    We propose an Individual-Based Model of ant-trail formation. The ants are modeled as self-propelled particles which deposit directed pheromone particles and interact with them through alignment interaction. The directed pheromone particles intend to model pieces of trails, while the alignment interaction translates the tendency for an ant to follow a trail when it meets it. Thanks to adequate quantitative descriptors of the trail patterns, the existence of a phase transition as the ant-pheromone interaction frequency is increased can be evidenced. We propose both kinetic and fluid descriptions of this model and analyze the capabilities of the fluid model to develop trail patterns. We observe that the development of patterns by fluid models require extra trail amplification mechanisms that are not needed at the Individual-Based Model level. PMID:22526837

  5. 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.

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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. PMID:26204442

  12. 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.

  13. 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.

  14. 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.

  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. 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.

  17. Targeted gene conversion induced by triplex-directed psoralen interstrand crosslinks in mammalian cells.

    PubMed

    Liu, Yaobin; Nairn, Rodney S; Vasquez, Karen M

    2009-10-01

    Correction of a defective gene is a promising approach for both basic research and clinical gene therapy. However, the absence of site-specific targeting and the low efficiency of homologous recombination in human cells present barriers to successful gene targeting. In an effort to overcome these barriers, we utilized triplex-forming oligonucleotides (TFOs) conjugated to a DNA interstrand crosslinking (ICL) agent, psoralen (pTFO-ICLs), to improve the gene targeting efficiency at a specific site in DNA. Gene targeting events were monitored by the correction of a deletion on a recipient plasmid with the homologous sequence from a donor plasmid in human cells. The mechanism underlying this event is stimulation of homologous recombination by the pTFO-ICL. We found that pTFO-ICLs are efficient in inducing targeted gene conversion (GC) events in human cells. The deletion size in the recipient plasmid influenced both the recombination frequency and spectrum of recombinants; i.e. plasmids with smaller deletions had a higher frequency and proportion of GC events. The polarity of the pTFO-ICL also had a prominent effect on recombination. Our results suggest that pTFO-ICL induced intermolecular recombination provides an efficient method for targeted gene correction in mammalian cells. PMID:19726585

  18. 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. PMID:23615169

  19. Measurement of the electrical properties of a polycrystalline cadmium telluride for direct conversion flat panel x-ray detector

    NASA Astrophysics Data System (ADS)

    Oh, K. M.; kim, D. K.; Shin, J. W.; Heo, S. U.; Kim, J. S.; Park, J. G.; Nam, S. H.

    2014-01-01

    Cadmium telluride (CdTe) is one of the best candidate direct conversion material for medical X-ray application because it satisfies the requirements of direct conversion x-ray material such as high atomic absorption, density, bandgap energy, work fuction, and resistivity. With such properties, single crystal CdTe exhibits high quantum efficiency and charge collection efficiency. However, for the development of low-cost large area detector, the study of the improvement of polycrystalline CdTe property is desirable. In this study, in order to improve the properties of polycrystalline CdTe, we produced polycrystalline CdTe with different kinds of raw materials, high purity Cd and Te powder compounds and bulk CdTe compound synthesized from single crystal CdTe. The electric properties including resistivity, x-ray sensitivity, and charge transport properties were investigated. As a result, polycrystalline CdTe exhibited simular level of resistivity and x-ray sensitivity to single crystal CdTe. The carrier transport properties of polycrystalline CdTe showed poorer properties than those of single crystal CdTe due to significant charge trapping. However, the polycrystalline CdTe fabricated with bulk CdTe compound synthesized from single crystal CdTe showed better charge transport properties than the polycrystalline CdTe fabricated with CdTe powder compounds. This is suitable for diagnostic x-ray detectors, especially for digital fluoroscopy.

  20. Plasma-based conversion of CO2: current status and future challenges.

    PubMed

    Bogaerts, Annemie; Kozák, Tomas; van Laer, Koen; Snoeckx, Ramses

    2015-01-01

    This paper discusses our recent results on plasma-based CO2 conversion, obtained by a combination of experiments and modeling, for a dielectric barrier discharge (DBD), a microwave plasma and a packed bed DBD reactor. The results illustrate that plasma technology is quite promising for CO2 conversion, but more research is needed to better understand the underlying mechanisms and to further improve the capabilities. PMID:26391907

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

    PubMed

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

    2016-04-11

    We report the direct conversion of mixed carboxylic acids to C-C olefins with up to 60 mol% carbon yield through cascade (cross) ketonization, (cross) aldolization and self-deoxygenation reactions. Co-feeding hydrogen provides an additional ketone hydrogenation/dehydration pathway to a wider range of olefins. PMID:26898532

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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 60Co 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. 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. PMID:25565406

  4. Direct conversion of mouse and human fibroblasts to functional melanocytes by defined factors.

    PubMed

    Yang, Ruifeng; Zheng, Ying; Li, Ling; Liu, Shujing; Burrows, Michelle; Wei, Zhi; Nace, Arben; Herlyn, Meenhard; Cui, Rutao; Guo, Wei; Cotsarelis, George; Xu, Xiaowei

    2014-01-01

    Direct reprogramming provides a fundamentally new approach for the generation of patient-specific cells. Here, by screening a pool of candidate transcription factors, we identify that a combination of the three factors, MITF, SOX10 and PAX3, directly converts mouse and human fibroblasts to functional melanocytes. Induced melanocytes (iMels) activate melanocyte-specific networks, express components of pigment production and delivery system and produce melanosomes. Human iMels properly integrate into the dermal-epidermal junction and produce and deliver melanin pigment to surrounding keratinocytes in a 3D organotypic skin reconstruct. Human iMels generate pigmented epidermis and hair follicles in skin reconstitution assays in vivo. The generation of iMels has important implications for studies of melanocyte lineage commitment, pigmentation disorders and cell replacement therapies. PMID:25510211

  5. Direct conversion of mouse and human fibroblasts to functional melanocytes by defined factors

    PubMed Central

    Yang, Ruifeng; Zheng, Ying; Li, Ling; Liu, Shujing; Burrows, Michelle; Wei, Zhi; Nace, Arben; Herlyn, Meenhard; Cui, Rutao; Guo, Wei; Cotsarelis, George; Xu, Xiaowei

    2015-01-01

    Direct reprogramming provides a fundamentally new approach for the generation of patient-specific cells. Here, by screening a pool of candidate transcription factors, we identify that a combination of three factors, MITF, SOX10 and PAX3, directly converts mouse and human fibroblasts to functional melanocytes. Induced melanocytes (iMels) activate melanocyte-specific networks, express components of pigment production and delivery system, and produce melanosomes. Human iMels properly integrate into the dermal-epidermal junction, and produce and deliver melanin pigment to surrounding keratinocytes in a 3D organotypic skin reconstruct. Human iMels generate pigmented epidermis and hair follicles in skin reconstitution assays in vivo. The generation of iMels has important implications for studies of melanocyte lineage commitment, pigmentation disorders and cell replacement therapies. PMID:25510211

  6. 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. PMID:10830854

  7. Direct interfaces for smart skins based on FPGAs

    NASA Astrophysics Data System (ADS)

    Oballe-Peinado, Óscar; Castellanos-Ramos, Julián; Hidalgo-López, José A.; Vidal-Verdú, Fernando

    2009-05-01

    Many artificial skins for robotics are based on piezoresistive films that cover an array of electrodes. Local preprocessing is a must in these systems to reduce errors and interferences and cope with the large amount of data provided by the sensor. This paper presents circuitry based on an FPGA to implement the interface to the artificial skin. The approach consists of a direct connection. The analog to digital conversion procedure is simple. It consists of measuring the discharging time of a capacitor through the resistance we want to read. This first proposed approach needs isolated tactels, so the raw sensor has to be fabricated in this way. If the tactile array is large, the strategy is not feasible. For instance, up to 288 pins are required to implement the interface with an array of 16x16 tactels. The proposal of this work for this case is to replace passive integrators by active ones. The result is a circuitry that allows the cancellation of interferences due to parasitic resistors and the sharing of the addressing tracks. Moreover, the FPGA allows the processing of data from the tactile sensor at a very high rate. This is because the high number of I/O pins of the device allows the conversion of many channels (in our case one per column) in parallel. The internal processing of the tactile image can also be done in parallel. This means we could be able to respond to very high demanding tasks in terms of dynamic requirements, like slippage detection. This also means we can run complex algorithms at real time, so a smart, programmable and powerful sensor is obtained.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

    2015-01-01

    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

  13. 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

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

    PubMed

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

    2016-01-01

    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. PMID:26685114

  15. Direct conversion of xylan to butanol by a wild-type Clostridium species strain G117.

    PubMed

    Yan, Yu; Basu, Anindya; Li, Tinggang; He, Jianzhong

    2016-08-01

    Lignocellulosic biomass has great potential for use as a carbon source for the production of second-generation biofuels by solventogenic bacteria. Here we describe the production of butanol by a newly discovered wild-type Clostridium species strain G117 with xylan as the sole carbon source for fermentation. Strain G117 produced 0.86 ± 0.07 g/L butanol and 53.4 ± 0.05 mL hydrogen directly from 60 g/L xylan provided that had undergone no prior enzymatic hydrolysis. After process optimization, the amount of butanol produced from xylan was increased to 1.24 ± 0.37 g/L. In contrast to traditional acetone-butanol-ethanol (ABE) solventogenic fermentation, xylan supported fermentation in strain G117 and negligible amount of acetone was produced. The expression of genes normally associated with acetone production (adc and ctfB2) were down-regulated compared to xylose fed cultures. This lack of acetone production may greatly simplify downstream separation process. Moreover, higher amount of butanol (2.94 g/L) was produced from 16.99 g/L xylo-oligosaccharides, suggesting a major role for strain G117 in butanol production from xylan and its oligosaccharides. The unique ability of strain G117 to produce a considerable amount of butanol directly from xylan without producing undesirable fermentation byproducts opens the door to the possibility of cost-effective biofuels production in a single step. Biotechnol. Bioeng. 2016;113: 1702-1710. © 2016 Wiley Periodicals, Inc. PMID:26803924

  16. 24 CFR 972.106 - Procedure for required conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Procedure for required conversion... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Required Conversion of Public Housing Developments Required...

  17. 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.

  18. A fully integrated direct-conversion digital satellite tuner in 0.18 μm CMOS

    NASA Astrophysics Data System (ADS)

    Si, Chen; Zengwang, Yang; Mingliang, Gu

    2011-04-01

    A fully integrated direct-conversion digital satellite tuner for DVB-S/S2 and ABS-S applications is presented. A broadband noise-canceling Balun-LNA and passive quadrature mixers provided a high-linearity low noise RF front-end, while the synthesizer integrated the loop filter to reduce the solution cost and system debug time. Fabricated in 0.18 μm CMOS, the chip achieves a less than 7.6 dB noise figure over a 900-2150 MHz L-band, while the measured sensitivity for 4.42 MS/s QPSK-3/4 mode is -91 dBm at the PCB connector. The fully integrated integer-N synthesizer operating from 2150 to 4350 MHz achieves less than 1 °C integrated phase error. The chip consumes about 145 mA at a 3.3 V supply with internal integrated LDOs.

  19. 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.

  20. 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. PMID:19964551

  1. 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.

  2. Direct conversion of human amniotic cells into endothelial cells without transitioning through a pluripotent state.

    PubMed

    Ginsberg, Michael; Schachterle, William; Shido, Koji; Rafii, Shahin

    2015-12-01

    Endothelial cells (ECs) have essential roles in organ development and regeneration, and therefore they could be used for regenerative therapies. However, generation of abundant functional endothelium from pluripotent stem cells has been difficult because ECs generated by many existing strategies have limited proliferative potential and display vascular instability. The latter difficulty is of particular importance because cells that lose their identity over time could be unsuitable for therapeutic use. Here, we describe a 3-week platform for directly converting human mid-gestation lineage-committed amniotic fluid-derived cells (ACs) into a stable and expandable population of vascular ECs (rAC-VECs) without using pluripotency factors. By transient expression of the ETS transcription factor ETV2 for 2 weeks and constitutive expression the ETS transcription factors FLI1 and ERG1, concomitant with TGF-β inhibition for 3 weeks, epithelial and mesenchymal ACs are converted, with high efficiency, into functional rAC-VECs. These rAC-VECs maintain their vascular repertoire and morphology over numerous passages in vitro, and they form functional vessels when implanted in vivo. rAC-VECs can be detected in recipient mice months after implantation. Thus, rAC-VECs can be used to establish a cellular platform to uncover the molecular determinants of vascular development and heterogeneity and potentially represent ideal ECs for the treatment of regenerative disorders. PMID:26540589

  3. Direct conversion of human amniotic cells into endothelial cells without transitioning through a pluripotent state

    PubMed Central

    Ginsberg, Michael; Schachterle, William; Shido, Koji; Rafii, Shahin

    2016-01-01

    Endothelial cells (ECs) have essential roles in organ development and regeneration, and therefore they could be used for regenerative therapies. However, generation of abundant functional endothelium from pluripotent stem cells has been difficult because ECs generated by many existing strategies have limited proliferative potential and display vascular instability. The latter difficulty is of particular importance because cells that lose their identity over time could be unsuitable for therapeutic use. Here, we describe a 3-week platform for directly converting human mid-gestation lineage-committed amniotic fluid–derived cells (ACs) into a stable and expandable population of vascular ECs (rAC-VECs) without using pluripotency factors. By transient expression of the ETS transcription factor ETV2 for 2 weeks and constitutive expression the ETS transcription factors FLI1 and ERG1, concomitant with TGF-β inhibition for 3 weeks, epithelial and mesenchymal ACs are converted, with high efficiency, into functional rAC-VECs. These rAC-VECs maintain their vascular repertoire and morphology over numerous passages in vitro, and they form functional vessels when implanted in vivo. rAC-VECs can be detected in recipient mice months after implantation. Thus, rAC-VECs can be used to establish a cellular platform to uncover the molecular determinants of vascular development and heterogeneity and potentially represent ideal ECs for the treatment of regenerative disorders. PMID:26540589

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

    PubMed

    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 10(2.8) to 10(5.8) 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

  5. 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

  6. 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.

  7. Polarization conversion system with liquid-crystal geometric-phase-based cylindrical lens

    NASA Astrophysics Data System (ADS)

    Honma, Michinori; Nose, Toshiaki

    2016-01-01

    We demonstrate a polarization conversion system by utilizing the polarization-splitting function of a liquid-crystal (LC) geometric-phase-based cylindrical lens. The system was constructed by combining the LC lens with a partially rubbed cell. The operation principle includes the following two steps. (i) The incident light is first decomposed into right- and left-handed circularly polarized light (RCP and LCP, respectively) as an attribute of geometric-phase-based optical elements. (ii) Then, only the RCP light is transformed into LCP light by passing it through the partially rubbed cell; as a result, the incident unpolarized light is converted into LCP light. We experimentally reveal the feasibility of the system by evaluating the effects, on the polarization conversion capability, of the diffraction efficiency, focal length, and partially rubbed cell’s retardation. The polarization conversion efficiency was obtained to be 65% on average for 400-700 nm and a maximum of 79% at 610 nm.

  8. Effective catalytic conversion of cellulose into high yields of methyl glucosides over sulfonated carbon based catalyst.

    PubMed

    Dora, Sambha; Bhaskar, Thallada; Singh, Rawel; Naik, Desavath Viswanatha; Adhikari, Dilip Kumar

    2012-09-01

    An amorphous carbon based catalyst was prepared by sulfonation of the bio-char obtained from fast pyrolysis (N(2) atm; ≈ 550°C) of biomass. The sulfonated carbon catalyst contained high acidity of 6.28 mmol/g as determined by temperature programmed desorption of ammonia of sulfonated carbon catalyst and exhibited high catalytic performance for the hydrolysis of cellulose. Amorphous carbon based catalyst containing -SO(3)H groups was successfully tested and the complete conversion of cellulose in methanol at moderate temperatures with high yields ca. ≥ 90% of α, β-methyl glucosides in short reaction times was achieved. The methyl glucosides formed in methanol are more stable for further conversion than the products formed in water. The carbon catalyst was demonstrated to be stable for five cycles with slight loss in catalytic activity. The utilization of bio-char as a sulfonated carbon catalyst provides a green and efficient process for cellulose conversion. PMID:22776237

  9. 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

  10. 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. PMID:19926117

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

    PubMed

    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

  12. 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

  13. 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

  14. 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,…

  15. Conversations about Curriculum Change: Mathematical Thinking and Team-Based Learning in a Discrete Mathematics Course

    ERIC Educational Resources Information Center

    Paterson, Judy; Sneddon, Jamie

    2011-01-01

    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…

  16. 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.

  17. 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. PMID:25675885

  18. 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.

  19. 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.

  20. 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.

  1. Mode conversion based on forward stimulated Brillouin scattering in a hybrid phononic-photonic waveguide.

    PubMed

    Chen, Guodong; Zhang, Ruiwen; Sun, Junqiang; Xie, Heng; Gao, Ya; Feng, Danqi; Xiong, Huang

    2014-12-29

    We propose a scheme for on-chip all optical mode conversion based on forward stimulated Brillouin scattering in a hybrid phononic-photonic waveguide. To describe the mode conversion the theoretical model of the FSBS is established by taking into account the radiation pressure and the electrostriction force simultaneously. The numerical simulation is carried out for the mode conversion from the fundamental mode E11x to the higher-order mode E21x. The results indicate that the mode conversion efficiency is affected by the waveguide length and the input pump light power, and the highest efficiency can reach upto 88% by considering the influence of optical and acoustic absorption losses in the hybrid waveguide. Additionally, the conversion bandwidth with approximate 12.5 THz can be achieved in 1550nm communication band. This mode converter on-chip is a promising device in the integrated optical systems, which can effectively increase the capacity of silicon data busses for on-chip optical interconnections. PMID:25607172

  2. Study on Conversion Between Momentum and Contrarian Based on Fractal Game

    NASA Astrophysics Data System (ADS)

    Wu, Xu; Song, Guanghui; Deng, Yan; Xu, Lin

    2015-06-01

    Based on the fractal game which is performed by the majority and the minority, the fractal market theory (FMT) is employed to describe the features of investors' decision-making. Accordingly, the process of fractal games is formed in order to analyze the statistical features of conversion between momentum and contrarian. The result shows that among three fractal game mechanisms, the statistical feature of simulated return rate series is much more similar to log returns on actual series. In addition, the conversion between momentum and contrarian is also extremely similar to real situation, which can reflect the effectiveness of using fractal game in analyzing the conversion between momentum and contrarian. Moreover, it also provides decision-making reference which helps investors develop effective investment strategy.

  3. 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. .

  4. Directional output distance functions: endogenous directions based on exogenous normalization constraints

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  5. 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

  6. Dose conversion coefficients based on the Chinese mathematical phantom and MCNP code for external photon irradiation.

    PubMed

    Qiu, Rui; Li, Junli; Zhang, Zhan; Liu, Liye; Bi, Lei; Ren, Li

    2009-02-01

    A set of conversion coefficients from kerma free-in-air to the organ-absorbed dose are presented for external monoenergetic photon beams from 10 keV to 10 MeV based on the Chinese mathematical phantom, a whole-body mathematical phantom model. The model was developed based on the methods of the Oak Ridge National Laboratory mathematical phantom series and data from the Chinese Reference Man and the Reference Asian Man. This work is carried out to obtain the conversion coefficients based on this model, which represents the characteristics of the Chinese population, as the anatomical parameters of the Chinese are different from those of Caucasians. Monte Carlo simulation with MCNP code is carried out to calculate the organ dose conversion coefficients. Before the calculation, the effects from the physics model and tally type are investigated, considering both the calculation efficiency and precision. In the calculation irradiation conditions include anterior-posterior, posterior-anterior, right lateral, left lateral, rotational and isotropic geometries. Conversion coefficients from this study are compared with those recommended in the Publication 74 of International Commission on Radiological Protection (ICRP74) since both the sets of data are calculated with mathematical phantoms. Overall, consistency between the two sets of data is observed and the difference for more than 60% of the data is below 10%. However, significant deviations are also found, mainly for the superficial organs (up to 65.9%) and bone surface (up to 66%). The big difference of the dose conversion coefficients for the superficial organs at high photon energy could be ascribed to kerma approximation for the data in ICRP74. Both anatomical variations between races and the calculation method contribute to the difference of the data for bone surface. PMID:19376886

  7. 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. PMID:18465368

  8. Direct Production of 5-Hydroxymethylfurfural via Catalytic Conversion of Simple and Complex Sugars over Phosphated TiO2.

    PubMed

    Atanda, Luqman; Shrotri, Abhijit; Mukundan, Swathi; Ma, Qing; Konarova, Muxina; Beltramini, Jorge

    2015-09-01

    A water-THF biphasic system containing N-methyl-2-pyrrolidone (NMP) was found to enable the efficient synthesis of 5-hydroxymethylfurfural (HMF) from a variety of sugars (simple to complex) using phosphated TiO2 as a catalyst. Fructose and glucose were selectively converted to HMF resulting in 98 % and 90 % yield, respectively, at 175 °C. Cellobiose and sucrose also gave rise to high HMF yields of 94 % and 98 %, respectively, at 180 °C. Other sugar variants such as starch (potato and rice) and cellulose were also investigated. The yields of HMF from starch (80-85 %) were high, whereas cellulose resulted in a modest yield of 33 %. Direct transformation of cellulose to HMF in significant yield (86 %) was assisted by mechanocatalytic depolymerization-ball milling of acid-impregnated cellulose. This effectively reduced cellulose crystallinity and particle size, forming soluble cello-oligomers; this is responsible for the enhanced substrate-catalytic sites contact and subsequent rate of HMF formation. During catalyst recyclability, P-TiO2 was observed to be reusable for four cycles without any loss in activity. We also investigated the conversion of the cello-oligomers to HMF in a continuous flow reactor. Good HMF yield (53 %) was achieved using a water-methyl isobutyl ketone+NMP biphasic system. PMID:26238933

  9. Enhanced Detection Efficiency of Direct Conversion X-ray Detector Using Polyimide as Hole-Blocking Layer

    PubMed Central

    Abbaszadeh, Shiva; Scott, Christopher C.; Bubon, Oleksandr; Reznik, Alla; Karim, Karim S.

    2013-01-01

    In this article we demonstrate the performance of a direct conversion amorphous selenium (a-Se) X-ray detector using biphenyldisnhydride/1,4 phenylenediamine (BPDA/PPD) polyimide (PI) as a hole-blocking layer. The use of a PI layer with a-Se allows detector operation at high electric fields (≥10 V/μm) while maintaining low dark current, without deterioration of transient performance. The hole mobility of the PI/a-Se device is measured by the time-of-flight method at different electric fields to investigate the effect of the PI layer on detector performance. It was found that hole mobility as high as 0.75 cm2/Vs is achievable by increasing the electric field in the PI/a-Se device structure. Avalanche multiplication is also shown to be achievable when using PI as a blocking layer. Increasing the electric field within a-Se reduces the X-ray ionization energy, increases hole mobility, and improves the dynamic range and sensitivity of the detector. PMID:24285255

  10. Enhanced Detection Efficiency of Direct Conversion X-ray Detector Using Polyimide as Hole-Blocking Layer

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, Shiva; Scott, Christopher C.; Bubon, Oleksandr; Reznik, Alla; Karim, Karim S.

    2013-11-01

    In this article we demonstrate the performance of a direct conversion amorphous selenium (a-Se) X-ray detector using biphenyldisnhydride/1,4 phenylenediamine (BPDA/PPD) polyimide (PI) as a hole-blocking layer. The use of a PI layer with a-Se allows detector operation at high electric fields (>=10 V/μm) while maintaining low dark current, without deterioration of transient performance. The hole mobility of the PI/a-Se device is measured by the time-of-flight method at different electric fields to investigate the effect of the PI layer on detector performance. It was found that hole mobility as high as 0.75 cm2/Vs is achievable by increasing the electric field in the PI/a-Se device structure. Avalanche multiplication is also shown to be achievable when using PI as a blocking layer. Increasing the electric field within a-Se reduces the X-ray ionization energy, increases hole mobility, and improves the dynamic range and sensitivity of the detector.

  11. Enhanced detection efficiency of direct conversion X-ray detector using polyimide as hole-blocking layer.

    PubMed

    Abbaszadeh, Shiva; Scott, Christopher C; Bubon, Oleksandr; Reznik, Alla; Karim, Karim S

    2013-01-01

    In this article we demonstrate the performance of a direct conversion amorphous selenium (a-Se) X-ray detector using biphenyldisnhydride/1,4 phenylenediamine (BPDA/PPD) polyimide (PI) as a hole-blocking layer. The use of a PI layer with a-Se allows detector operation at high electric fields (≥10 V/μm) while maintaining low dark current, without deterioration of transient performance. The hole mobility of the PI/a-Se device is measured by the time-of-flight method at different electric fields to investigate the effect of the PI layer on detector performance. It was found that hole mobility as high as 0.75 cm(2)/Vs is achievable by increasing the electric field in the PI/a-Se device structure. Avalanche multiplication is also shown to be achievable when using PI as a blocking layer. Increasing the electric field within a-Se reduces the X-ray ionization energy, increases hole mobility, and improves the dynamic range and sensitivity of the detector. PMID:24285255

  12. 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.

  13. 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.

  14. 24 CFR 972.106 - Procedure for required conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... of public housing developments to tenant-based assistance. 972.106 Section 972.106 Housing and Urban... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Required Conversion of Public Housing Developments Required...

  15. 24 CFR 972.106 - Procedure for required conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... of public housing developments to tenant-based assistance. 972.106 Section 972.106 Housing and Urban... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Required Conversion of Public Housing Developments Required...

  16. 24 CFR 972.209 - Procedure for voluntary conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... of public housing developments to tenant-based assistance. 972.209 Section 972.209 Housing and Urban... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Voluntary Conversion of Public Housing Developments...

  17. 24 CFR 972.209 - Procedure for voluntary conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... of public housing developments to tenant-based assistance. 972.209 Section 972.209 Housing and Urban... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Voluntary Conversion of Public Housing Developments...

  18. 24 CFR 972.209 - Procedure for voluntary conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... of public housing developments to tenant-based assistance. 972.209 Section 972.209 Housing and Urban... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Voluntary Conversion of Public Housing Developments...

  19. 24 CFR 972.209 - Procedure for voluntary conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... of public housing developments to tenant-based assistance. 972.209 Section 972.209 Housing and Urban... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Voluntary Conversion of Public Housing Developments...

  20. 24 CFR 972.106 - Procedure for required conversion of public housing developments to tenant-based assistance.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... of public housing developments to tenant-based assistance. 972.106 Section 972.106 Housing and Urban... FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT CONVERSION OF PUBLIC HOUSING TO TENANT-BASED ASSISTANCE Required Conversion of Public Housing Developments Required...

  1. Truck co-generation system based on combustion heated thermoelectric conversion

    SciTech Connect

    Meleta, Ye.A.; Yarygin, V.I.; Klepikov, V.V.; Wolff, L.R.

    1997-12-31

    Among the micro-co-generation systems using direct conversion of combustion heat into electricity (thermionic, thermoelectric converters) and fuel cells with an electric power of up to several kW, only the thermoelectric co-generation systems have a demonstrated life-time of up to 10 years. This is one of the most important factors making these systems a more likely commercialization candidate. The report deals with a conceptual design of a combustion heated thermoelectric cogeneration system to be applied in vehicles (truck, trailer, yacht, etc.). The authors named these systems the Thermoelectric Transport Co-generation Systems (TTCS). The report is concerned with one example of these systems--the Thermoelectric Truck Co-generation System (TT-kCS) designed to support the lives of both the driver and the car, when operating in the northern regions. In particular, the TT-kCS should provide the start-up of the cold engine of a truck at an ambient temperature of down to 50 C below zero and create comfortable conditions for a driver during the long-term halts and in emergency situations. The estimates made for a standard truck with an engine of 210 HP employed in Russia showed that the TT-kCS should generate {approximately}600 W of electrical power and {approximately}18 kW of heat. The report deals with two options for the thermoelectric converter design: one of them using the planar geometry of thermoelectric batteries, and the other one using a radial-cylindrical thermoelectric battery configuration. The economic feasibility of the TT-kCS application is based on a considerable reduction in fuel consumption of the TT-kCS equipped truck as compared to that of a conventional truck when the engine is idling. Another advantage is the prolongation of the engine`s service life.

  2. 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

  3. 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

  4. An environmentally compliant cerium-based conversion coating for aluminum protection

    NASA Astrophysics Data System (ADS)

    Lin, Xuan

    Chromate conversion coatings have been extensively used in the aircraft industry for the corrosion protection of aluminum alloys. Unfortunately, hexavalent chromium, which is a primary component in the chromating process, is a confirmed carcinogen. Because of rising remediation and disposal costs caused by increasingly strict regulations, the replacement of the traditional chromate conversion process is becoming a top priority in the metal finishing industry. This research focused on the electrodeposition of cerium-based coatings on 7075-T6 aluminum alloy in an electrolyte containing a cerium salt, an oxidizing agent and an organic solvent. The cerium-rich deposits were characterized by phase composition, oxidation state, coating thickness, surface morphology, deposition mechanism and polarization behavior. Chemical and electrochemical tests were utilized to compare the corrosion resistance between cerium-based coatings and chromate conversion coatings. To characterize and simulate the deposition process, a variety of approaches were utilized to study the oxidation states of cerium in various soluble and precipitated forms as a function of hydrogen peroxide and electrolyte pH. The pH ranges where the oxidation and reduction reactions dominate were determined. Further studies were performed to optimize the corrosion performance of cerium-based coatings and to understand the effects of electrolyte constituents and deposition parameters. The optimum levels for these variables were identified. A patent disclosure on the cerium-based coating process was made to the University of Missouri-Rolla and has now been officially filed with the U.S. Patent Office.

  5. 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. PMID:27430282

  6. 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

    2016-04-01

    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. PMID:26627913

  7. Two-dimensionally tunable microwave signal generation based on optical frequency-to-time conversion.

    PubMed

    Ye, Jia; Yan, Lianshen; Pan, Wei; Luo, Bin; Zou, Xihua; Yi, Anlin; Yao, Xiaotian Steve

    2010-08-01

    We propose and experimentally demonstrate an all-fiber-based approach to generate microwave signals with tunable frequency and pulse width. The adjustable optical power spectrum can be achieved using a spectrum shaper, consisting of a variable differential-group-delay element and a bandwidth-tunable optical filter. Through the frequency-to-time conversion in the dispersive fiber, the frequency and pulse width of the obtained microwave signals can be user defined by modifying the optical spectrum shape. PMID:20680073

  8. 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.

  9. Direct conversion of allyl arenes to aryl ethylketones via a TBHP-mediated palladium-catalyzed tandem isomerization-Wacker oxidation of terminal alkenes.

    PubMed

    Zhao, JinWu; Liu, Li; Xiang, ShiJian; Liu, Qiang; Chen, HuoJi

    2015-05-28

    A TBHP-mediated palladium-catalyzed tandem isomerization-Wacker oxidation of terminal alkenes was developed. This methodology provides a new efficient and simple route for conversion of a range of allyl arenes directly into aryl ethylketones in good yields with high chemoselectivity. PMID:25884269

  10. 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

  11. 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.

  12. 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.

  13. 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. PMID:23192801

  14. 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.

  15. 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.

  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. Biologically inspired MEMS based directional microphone

    NASA Astrophysics Data System (ADS)

    Touse, Michael; Harrison, Stephen; Catterlin, Jeffrey; Karunasiri, Gamani

    2009-11-01

    A novel MEMS microphone is presented which mimics the aural system of the Ormia ochracea fly and its extraordinary directional sensitivity. To overcome the minimal separation between its ears, a flexible hinge mechanically couples the fly's two tympanic membranes. By comparing the frequency response of these two structures, the interaural differences are amplified and sound source information is processed with unparalleled speed and accuracy. The presented device is 2mm x 1mm x 10μm SOI, hinged at the middle and attached to the substrate using two narrow legs, allowing both rocking and bending modes. Along the edges of the membrane, two sets of interdigitated comb fingers are connected to an Irvine Sensors capacitive readout chip to allow electronic measurement of the displacement. Also presented are results of extensive finite element modeling performed using COMSOL Multiphysics, which are in close agreement with experimental data.

  18. Direct Energy Conversion Fission Reactor, Gaseous Core Reactor with Magnetohydrodynamic (MHD) Generator; Final Report - Part I and Part II

    SciTech Connect

    Samim Anghaie; Blair Smith; Travis Knight

    2002-11-12

    This report focuses on the power conversion cycle and efficiency. The technical issues involving the ionization mechanisms, the power management and distribution and radiation shielding and safety will be discussed in future reports.

  19. 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

    2014-01-01

    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

  20. 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.

  1. The effect of converter efficiency on DEAP-based energy conversion: an overview and optimization method

    NASA Astrophysics Data System (ADS)

    van Kessel, Rick; Wattez, Ambroise; Bauer, Pavol

    2014-03-01

    This work presents an integral approach to the power electronic challenges that are faced in DEAP-based energy conversion, such as wide converter operating ranges and high peak-to-average ratios. It is shown that for small strain cycles, the losses in the Power Electronic Converter (PEC) due to the cyclic charging and discharging are dominant. The efficiency profile of a realistic, high-voltage modular PEC was measured and fed into an optimization algorithm. The current amplitude, phase and shape are optimized, and different cycle types are compared. With optimization results for a wide strain range, it is demonstrated that with properly adapted harvesting cycles, the overall conversion efficiency is significantly improved, especially for small strain cycles.

  2. 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. PMID:27189138

  3. 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

  4. Assessment of risk-based capacity benefit factors associated with wind energy conversion systems

    SciTech Connect

    Billinton, R.; Chen, H.

    1998-08-01

    A Wind Energy Conversion System (WECS) has a different impact on the load carry capability of a generating system than does a conventional energy conversion system. This is mainly due to the variation in wind velocity. Two risk-based capacity indices designated as Load Carrying Capacity Benefit Ratio (LCCBR) and Equivalent Capacity Rate (ECR) are introduced in this paper. These two indices can be used to indicate capacity benefit and credit of a WECS, and thus provide valuable information for energy policy makers in decision problems involving the selection and classification of wind sites. A midpoint sectionalized technique has been developed to calculate the Incremental Peak Load Carrying Capability (IPLCC) and to assess the LCCBR and ECR. The technique is effective and usually takes only a few iterations to obtain the indices. Sequential Monte Carlo simulation is utilized to estimate the adequacy of a generating system including WECS. A small reliability test system containing WECS is utilized to illustrate the proposed technique.

  5. Transparent sunlight conversion film based on carboxymethyl cellulose and carbon dots.

    PubMed

    You, Yaqin; Zhang, Haoran; Liu, Yingliang; Lei, Bingfu

    2016-10-20

    Transparent sunlight conversion film based on carboxymethyl cellulose (CMC) and carbon dots (CDs) has been developed for the first time through dispersion of CDs in CMC aqueous solution. Due to the hydrogen bonds interaction, CMC can effectively absorb the CDs, whose surfaces are functionalized by lots of polar groups. The results from atomic force microscopy (AFM), scanning electron microscopy (SEM) confirm that the composite film possesses a homogeneous and compact structure. Besides, the CMC matrix neither competes for absorbing excitation light nor absorbs the emissions of CDs, which reserves the inherent optical properties of the individual CDs. The composite films can efficiently convert ultraviolet light to blue light. What's more, the film is transparent and possesses excellent mechanical properties, expected to apply in the field of agricultural planting for sunlight conversion. PMID:27474564

  6. Symmetry-based coding method and synthesis topology optimization design of ultra-wideband polarization conversion metasurfaces

    NASA Astrophysics Data System (ADS)

    Sui, Sai; Ma, Hua; Wang, Jiafu; Feng, Mingde; Pang, Yongqiang; Xia, Song; Xu, Zhuo; Qu, Shaobo

    2016-07-01

    In this letter, we propose the synthesis topology optimization method of designing ultra-wideband polarization conversion metasurface for linearly polarized waves. The general design principle of polarization conversion metasurfaces is derived theoretically. Symmetry-based coding, with shorter coding length and better optimization efficiency, is then proposed. As an example, a topological metasurface is demonstrated with an ultra-wideband polarization conversion property. The results of both simulations and experiments show that the metasurface can convert linearly polarized waves into cross-polarized waves in 8.0-30.0 GHz, obtaining the property of ultra-wideband polarization conversion based on metasurfaces, and hence validating the synthesis design method. The proposed method combines the merits of topology optimization and symmetry-based coding method, which provides an efficient tool for the design of high-performance polarization conversion metasurfaces.

  7. 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...

  8. 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...

  9. 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. PMID:21799983

  10. 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.

  11. 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.

  12. Tin Ion Directed Morphology Evolution of Copper Sulfide Nanoparticles and Tuning of Their Plasmonic Properties via Phase Conversion.

    PubMed

    Chen, Lihui; Sakamoto, Masanori; Haruta, Mitsutaka; Nemoto, Takashi; Sato, Ryota; Kurata, Hiroki; Teranishi, Toshiharu

    2016-08-01

    Copper-deficient copper sulfide (Cu2-xS) nanoparticles (NPs) have been investigated as important hole-based plasmonic materials because of their size, morphology, and carrier density-dependent localized surface plasmon resonance (LSPR) properties. Morphology and carrier density are two important parameters to determine their LSPR properties. Here, we demonstrate that the foreign metal ion, Sn(4+), directs the growth of djurleite Cu31S16 from nanodisk to tetradecahedron along the [100] direction. To control the LSPR properties by tuning the carrier density, the djurleite Cu31S16 nanoparticles were pseudomorphically converted into more copper-deficient (higher carrier density) roxbyite Cu7S4 NPs by heat treatment in the presence of amine. The roxbyite Cu7S4 NPs exhibited a shorter and stronger LSPR peak while retaining the morphology of the djurleite Cu31S16 NPs. PMID:27398864

  13. 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.

  14. Dynamic tracking down-conversion signal processing method based on reference signal for grating heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Guochao; Yan, Shuhua; Zhou, Weihong; Gu, Chenhui

    2012-08-01

    Traditional displacement measurement systems by grating, which purely make use of fringe intensity to implement fringe count and subdivision, have rigid demands for signal quality and measurement condition, so they are not easy to realize measurement with nanometer precision. Displacement measurement with the dual-wavelength and single-grating design takes advantage of the single grating diffraction theory and the heterodyne interference theory, solving quite well the contradiction between large range and high precision in grating displacement measurement. To obtain nanometer resolution and nanometer precision, high-power subdivision of interference fringes must be realized accurately. A dynamic tracking down-conversion signal processing method based on the reference signal is proposed. Accordingly, a digital phase measurement module to realize high-power subdivision on field programmable gate array (FPGA) was designed, as well as a dynamic tracking down-conversion module using phase-locked loop (PLL). Experiments validated that a carrier signal after down-conversion can constantly maintain close to 100 kHz, and the phase-measurement resolution and phase precision are more than 0.05 and 0.2 deg, respectively. The displacement resolution and the displacement precision, corresponding to the phase results, are 0.139 and 0.556 nm, respectively.

  15. Photon fluence-to-effective dose conversion coefficients calculated from a Saudi population-based phantom

    NASA Astrophysics Data System (ADS)

    Ma, A. K.; Altaher, K.; Hussein, M. A.; Amer, M.; Farid, K. Y.; Alghamdi, A. A.

    2014-02-01

    In this work we will present a new set of photon fluence-to-effective dose conversion coefficients using the Saudi population-based voxel phantom developed recently by our group. The phantom corresponds to an average Saudi male of 173 cm tall weighing 77 kg. There are over 125 million voxels in the phantom each of which is 1.37×1.37×1.00 mm3. Of the 27 organs and tissues of radiological interest specified in the recommendations of ICRP Publication 103, all but the oral mucosa, extrathoracic tissue and the lymph nodes were identified in the current version of the phantom. The bone surface (endosteum) is too thin to be identifiable; it is about 10 μm thick. The dose to the endosteum was therefore approximated by the dose to the bones. Irradiation geometries included anterior-posterior (AP), left (LLAT) and rotational (ROT). The simulations were carried out with the MCNPX code version 2.5.0. The fluence in free air and the energy depositions in each organ were calculated for monoenergetic photon beams from 10 keV to 10 MeV to obtain the conversion coefficients. The radiation and tissue weighting factors were taken from ICRP Publication 60 and 103. The results from this study will also be compared with the conversion coefficients in ICRP Publication 116.

  16. Modeling of plasma-based CO2 conversion: lumping of the vibrational levels

    NASA Astrophysics Data System (ADS)

    Berthelot, Antonin; Bogaerts, Annemie

    2016-08-01

    Although CO2 conversion by plasma technology is gaining increasing interest, the underlying mechanisms for an energy-efficient process are still far from understood. In this work, a reduced non-equilibrium CO2 plasma chemistry set, based on level lumping of the vibrational levels, is proposed and the reliability of this level-lumping method is tested by a self-consistent zero-dimensional code. A severe reduction of the number of equations to be solved is achieved, which is crucial to be able to model non-equilibrium CO2 plasmas by 2-dimensional models. Typical conditions of pressure and power used in a microwave plasma for CO2 conversion are investigated. Several different sets, using different numbers of lumped groups, are considered. The lumped models with 1, 2 or 3 groups are able to reproduce the gas temperature, electron density and electron temperature profiles, as calculated by the full model treating all individual excited levels, in the entire pressure range investigated. Furthermore, a 3-groups model is also able to reproduce the shape of the vibrational distribution function (VDF) and gives the most reliable prediction of the CO2 conversion. A strong influence of the vibrational excitation on the plasma characteristics is observed. Finally, the limitations of the lumped-levels method are discussed.

  17. 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.

  18. 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

  19. Gene array analysis of neural crest cells identifies transcription factors necessary for direct conversion of embryonic fibroblasts into neural crest cells.

    PubMed

    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

    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

  20. 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

  1. 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

    2016-06-01

    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.

  2. Widely tunable polarization maintaining photonic crystal fiber based parametric wavelength conversion.

    PubMed

    Murray, Robert T; Kelleher, Edmund J R; Popov, Sergei V; Mussot, Arnaud; Kudlinski, Alexandre; Taylor, James R

    2013-07-01

    We report a near-visible parametric wavelength converter comprising a polarization-maintaining photonic crystal fiber (PM-PCF) pumped by a highly versatile diode-seeded master-oscillator power amplifier system based around 1.06 μm. The device is broadly tunable in wavelength (0.74-0.81 μm), pulse duration (0.2-1.5 ns) and repetition rate (1-30 MHz). A maximum anti-Stokes slope conversion efficiency of 14.9% is achieved with corresponding anti-Stokes average output powers of 845 mW, at a wavelength of 0.775 μm. PMID:23842368

  3. 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) . PMID:26445101

  4. Directed Growth of Metal-Organic Frameworks and Their Derived Carbon-Based Network for Efficient Electrocatalytic Oxygen Reduction.

    PubMed

    Li, Zhenhua; Shao, Mingfei; Zhou, Lei; Zhang, Ruikang; Zhang, Cong; Wei, Min; Evans, David G; Duan, Xue

    2016-03-23

    A honeycomb-like carbon-based network is obtained by in situ nucleation and directed growth of metal-organic framework (MOF) arrays on the surface of layered double hydroxide (LDH) nanoplatelets, followed by a subsequent pyrolysis process, which exhibits largely enhanced electrocatalytic ORR performances. A successful paradigm for the directed growth of highly oriented MOF arrays is demonstrated, with potential applications for energy storage and conversion. PMID:26808408

  5. 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

  6. 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. PMID:27563577

  7. 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. PMID:23395737

  8. 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." PMID:19451407

  9. 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.

  10. 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

  11. 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.

  12. 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. PMID:25824595

  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. Photoelectric conversion characteristics of c-Se-based thin-film photodiodes in imaging device

    NASA Astrophysics Data System (ADS)

    Imura, S.; Kikuchi, K.; Miyakawa, K.; Ohtake, H.; Kubota, M.

    2015-06-01

    Herein, we report the use of high-efficiency crystalline-selenium-based (c-Se-based) thin-film heterojunction photodiodes in imaging devices. As a novel experiment, we use an image pickup tube with a photoelectric conversion layer consisting of n-gallium oxide (Ga2O3)/p-c-Se heterojunction photodiodes to obtain high-resolution images at a relatively low applied voltage. We reduce the thickness of the Ga2O3 layer to expand the depletion layer into the c-Se layer at a lower applied voltage. In addition, Sn-doping of the Ga2O3 layer effectively increases the carrier concentration, thereby allowing the photodiode to operate at lower voltage.

  15. 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.

  16. 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. PMID:24663730

  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. 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. PMID:24515046

  19. Dental resins based on dimer acid dimethacrylates: a route to high conversion with low polymerization shrinkage.

    PubMed

    Lu, Hui; Trujillo-Lemon, Marianela; Ge, Junhao; Stansbury, Jeffrey W

    2010-05-01

    Incomplete polymerization, volumetric shrinkage, and shrinkage stress are among the primary disadvantages of current resin-based dental composites. Generally, any attempt to increase final double bond conversion only exacerbates polymerization shrinkage and stress. The use of dimer acid-derived dimethacrylate (DADMA) monomers in novel dental resin formulations is examined in this article as a potential means to address these disparate goals. A series of high molecular weight DADMA monomers with different functional groups used to connect the C36 dimer acid core and the methacrylates were formulated with urethane dimethacrylate (UDMA) and/or ethoxylated bisphenol A dimethacrylate (Bis-EMA) at various compositions to manipulate comonomer compatibility and polymeric mechanical properties. Along with reaction kinetics, dynamic polymerization shrinkage and shrinkage stress were assessed. Specific DADMA monomers demonstrated limited miscibility with either Bis-EMA or UDMA. Appropriate ternary resin formulations produced homogeneous monomeric mixtures capable of controlled polymerization-induced phase separation (PIPS) to yield heterogeneous final polymers. Reduced polymerization shrinkage and stress along with higher conversion was observed for DADMA ternary systems compared with a bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) resin control. The PIPS process resulted in a modest volume recovery and stress relaxation in the later stages of polymerization. These results indicate that certain dimer acid-derived dimethacrylates possess the potential to replace TEGDMA as a reactive diluent in dental resins that display a favorable and unique combination of properties. PMID:20521567

  20. 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. PMID:25755072

  1. Taste masking of propiverine hydrochloride by conversion to its free base.

    PubMed

    Ogata, Tetsuo; Koide, Atsuo; Kinoshita, Masahiro; Ozeki, Tetsuya

    2012-01-01

    The aim of the present study was to mask the bitterness of propiverine hydrochloride (P-4) by converting it to propiverine free base. Fine granules comprising the free base, which was converted from P-4 by desalination, were prepared. By using Fourier transform infrared spectroscopy, thermogravimetry-differential thermal analysis, and powder X-ray diffraction spectra, we confirmed that P-4 had been converted into propiverine free base by desalination during the manufacturing process. Furthermore, the conversion into free base appeared to result in decreased solubility, and both the taste testing sensor and tasting volunteers determined that it masked the bitterness of P-4. On using the gustatory sensation test, the bitterness of the P-4 fine granules was confirmed to be weakened. The dissolution rate and bioavailability of fine granules of the free base were compared with tablets of P-4. The dissolution rate and bioavailability of the fine granules and tablets were almost the same. We successfully masked the taste of P-4 by converting it into free base using a manufacturing process that was suitable for commercial manufacturing. PMID:22863700

  2. 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

    2016-09-01

    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. PMID:27607638

  3. Direct comparison of full-wave and ray-tracing methods for a simple model of multi-dimensional mode conversion

    NASA Astrophysics Data System (ADS)

    Xiao, Y.; Richardson, A.; Tracy, E.

    2007-11-01

    Mode conversion can occur in a nonuniform plasma when two waves of different character are locally resonant. Jaun et al. have recently developed a numerical ray-tracing algorithm for realistic tokamak models that accounts for the ray splitting that occurs at conversions [1,2]. Here we present a comparison of ray-based and full-wave methods by considering a simple model consisting of a pair of coupled wave equations in two spatial dimensions. The two spatially-dependent wave speeds, c1(x,y) and c2(x,y) are distinct for almost all (x,y), and are equal only along a line where conversion occurs. We launch a WKB-type wave packet in channel 1. There is initially no excitation in channel 2. Absorbing boundary conditions are used to avoid reflections which would complicate the results. From the full-wave output, we compute the initial energy density as a function of position and consider its evolution along a family of rays which undergo conversion. These full-wave results are then compared to the ray-based predictions. [1] A.Jaun, E.Tracy and A.Kaufman, Plasma Phys. Control. Fusion 49, 43-67 (2007). [2] E.Tracy, A.Kaufman and A.Jaun, to appear in Phys. Plasmas.

  4. 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

  5. Multiband one-way polarization conversion in complementary split-ring resonator based structures by combining chirality and tunneling.

    PubMed

    Serebryannikov, Andriy E; Beruete, Miguel; Mutlu, Mehmet; Ozbay, Ekmel

    2015-05-18

    Multiband one-way polarization conversion and strong asymmetry in transmission inspired by it are demonstrated in ultrathin sandwiched structures that comprise two twisted aperture-type arrays of complementary split-ring resonators (CSRRs), metallic mesh, and dielectric layers. The basic features of the resulting mechanism originate from the common effect of chirality and tunneling. The emphasis is put on the (nearly) perfect polarization conversion of linear incident polarization into the orthogonal one and related diodelike asymmetric transmission within multiple narrow bands. Desired polarization conversion can be obtained at several resonances for one of the two opposite incidence directions, whereas transmission is fully blocked for the other one. The resonances, at which the (nearly) perfect conversion takes place, are expected to be inherited from similar structures with parallel, i.e., not rotated CSRR arrays that do not enable chirality and, thus, polarization conversion. It is found that the basic transmission and polarization conversion features and, thus, the dominant physics are rather general, enabling efficient engineering of such structures. The lowest-frequency resonance can be obtained in structures made of conventional materials with total thickness less than λ/50 and up to ten such resonances can correspond to thickness less than λ/20. PMID:26074599

  6. 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.

  7. Reaction Mechanism of Siderite Lump in Coal-Based Direct Reduction

    NASA Astrophysics Data System (ADS)

    Zhu, Deqing; Luo, Yanhong; Pan, Jian; Zhou, Xianlin

    2016-02-01

    Siderite is one of the significant iron ore resources in China and yet is difficult to upgrade by traditional beneficiation processes. A process of coal-based direct reduction-magnetic separation was successfully developed for the beneficiation of siderite. However, few studies have thoroughly investigated the mechanism of the direct reduction of siderite. In order to reveal the reaction mechanism of coal-based direct reduction of siderite lump, thermodynamics of direct reduction was investigated with coal as the reductant. The thermodynamics results indicate that coal-based direct reduction process of siderite lump at 1,050°C follows the steps as FeCO3→ Fe3O4→ FeO → Fe, which is verified by chemical titration analysis, X-ray diffraction and scanning electron microscope. The microstructure of siderite sample varies with different reduction stages and some 45% porosity induced by thermal decomposition of siderite is conductive to subsequent reduction. The conversion of FeO to Fe is the main reduction rate-controlling step. The reduced product with the metallic iron size over 30 μm can be effectively beneficiated by wet magnetic separation after grinding. The obvious layered structure of reduced product is due to different heat transfer resistance, CO and CO2 concentration.

  8. Studies of in-situ calcium-based sorbents in advanced pressurized coal conversion systems

    SciTech Connect

    Katta, S.; Shires, P.J.; O'Donnell, J.J.

    1992-01-01

    The overall objective of the project is to obtain experimental data on the reactions of calcium-based sorbents in gasification systems and to evaluate or develop kinetic models applicable to the commercial design of such systems. Both air-blown coal gasification systems and second generation fluid bed combustion systems (partial gasification) will be investigated, as well as subsequent stabilization of the solid wastes (calcium sulfide/ash) produced. More specifically, the objectives are to: Develop data on kinetics of in-situ desulfurization reactions; study the effect of calcium on the kinetics of carbon conversion rate; study kinetics of oxidation of CaS to CaSO[sup 4]; Develop and identify viable techniques to stabilize CaS; and, carry out further development work on most promising method and determine its commercial economics.

  9. Studies of in-situ calcium-based sorbents in advanced pressurized coal conversion systems

    SciTech Connect

    Katta, S.; Shires, P.J.; O`Donnell, J.J.

    1992-11-01

    The overall objective of the project is to obtain experimental data on the reactions of calcium-based sorbents in gasification systems and to evaluate or develop kinetic models applicable to the commercial design of such systems. Both air-blown coal gasification systems and second generation fluid bed combustion systems (partial gasification) will be investigated, as well as subsequent stabilization of the solid wastes (calcium sulfide/ash) produced. More specifically, the objectives are to: Develop data on kinetics of in-situ desulfurization reactions; study the effect of calcium on the kinetics of carbon conversion rate; study kinetics of oxidation of CaS to CaSO{sup 4}; Develop and identify viable techniques to stabilize CaS; and, carry out further development work on most promising method and determine its commercial economics.

  10. 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.

  11. 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.

  12. All-optical analog-to-digital conversion scheme based on Sagnac loop and balanced receivers.

    PubMed

    Xu, Kun; Niu, Jian; Dai, Yitang; Sun, Xiaoqiang; Dai, Jian; Wu, Jian; Lin, Jintong

    2011-05-10

    An all-optical analog-to-digital conversion scheme based on a Sagnac loop and balanced receivers is proposed and experimentally demonstrated. Adjustable phase shift about the transfer function of the Sagnac loop is obtained by using the multiwavelength optical pulses to realize the phase-shift optical quantization. Benefit from the complementary outputs at the transmitted and reflected ports of the Sagnac loop and balanced receiver can be used to obtain the quantized output binary signal for the encoding operation. A proof-of-concept experiment is implemented using a wavelength tunable continuous-wave laser diode. Using 16 different wavelengths, the 16 quantization levels are demonstrated and an effective number of bits (ENOB) of 4 bits is obtained. PMID:21556099

  13. NaBH4 generator integrated with energy conversion device based on hydrogen combustion

    NASA Astrophysics Data System (ADS)

    Netskina, O. V.; Fursenko, R. V.; Komova, O. V.; Odintsov, E. S.; Simagina, V. I.

    2015-01-01

    A thermoelectric energy conversion device operating on the heat generated by a hydrogen diffusion microflame has been developed. For the first time, a NaBH4 hydrogen generator has been employed as a source of fuel for such type of power generator. A 1%Ru-3%Co/Sibunit catalyst ensures hydrogen generation at a rate of 3 cm3 s-1 during 3 h. Power and efficiency characteristics of the integrated system consisting of a hydrogen generator and an energy converter based on combustion technologies have been studied experimentally. The total efficiency and the generated power of the system were measured to achieve values of up to 1.23% and 0.25 W, respectively. Ways to further improve the system's power output and efficiency characteristics have been discussed.

  14. Rotation and conversion of transmission mode based on a rotatable elliptical core ring resonator

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Liu, Yun-Feng; Li, Shu-Jing; He, Xing-Dao

    2016-06-01

    A compact plasmonic waveguide system consisting of a rotating elliptical core ring (ECR) coupled two metal-insulator-metal (MIM) waveguides is proposed. Influences of the eccentricity and rotation angle of the elliptical core on the transmission characteristics are studied in detail, by using Finite-Difference Time-Domain (FDTD) method. Compared with circular core in ring resonator, the elliptical core will lead to the asymmetric field distributions of intrinsic mode. Based on this, a 1×2 splitter is designed, in which the beam-splitting ratio can be adjusted by changing the eccentricity of the elliptical core. In addition, we find that the intrinsic mode of ECR rotate with elliptical core and gradually convert to its orthogonal mode. Separation of the pair orthogonal modes increases with growth of the eccentricity of the elliptical core. And, the higher order intrinsic mode corresponds to the shorter rotation angle of mode conversion.

  15. PMD mitigation using 3R regeneration based on EAM with wavelength conversion

    NASA Astrophysics Data System (ADS)

    Huo, Li; Pan, Shilong; Yang, Yanfu; Lou, Caiyun; Gao, Yizhi

    2006-03-01

    Polarization mode dispersion (PMD) mitigation is performed using an optical 3R (re-amplification, re-shaping, re-timing) regenerator based on electro-absorption modulator (EAM) with wavelength conversion. System performance without and with 3R regeneration was separately studied by eye analysis and bit-error rate (BER) measurements. The signal quality was significantly improved by 3R regeneration under serious first order PMD (up to 40% of the bit interval) combined with second order PMD (up to about 520 ps2). The PMD mitigation margin of the proposed method is also investigated by measuring the sensitivity at BER 10^(-10). Further studies indicate that 3R regenerators have the potential to combat with the effects of PMD combined with polarization dependent loss (PDL) and polarization hole-burning (PHB).

  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 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.

  18. 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.

  19. A stereoscopic video conversion scheme based on spatio-temporal analysis of MPEG videos

    NASA Astrophysics Data System (ADS)

    Lin, Guo-Shiang; Huang, Hsiang-Yun; Chen, Wei-Chih; Yeh, Cheng-Ying; Liu, Kai-Che; Lie, Wen-Nung

    2012-12-01

    In this article, an automatic stereoscopic video conversion scheme which accepts MPEG-encoded videos as input is proposed. Our scheme is depth-based, relying on spatio-temporal analysis of the decoded video data to yield depth perception cues, such as temporal motion and spatial contrast, which reflect the relative depths between the foreground and the background areas. Our scheme is shot-adaptive, demanding that shot change detection and shot classification be performed for tuning of algorithm or parameters that are used for depth cue combination. The above-mentioned depth estimation is initially block-based, followed by a locally adaptive joint trilateral upsampling algorithm to reduce the computing load significantly. A recursive temporal filter is used to reduce the possible depth fluctuations (and also artifacts in the synthesized images) resulting from wrong depth estimations. The traditional Depth-Image-Based-Rendering algorithm is used to synthesize the left- and right-view frames for 3D display. Subjective tests show that videos converted by our scheme provide comparable perceived depth and visual quality with those converted from the depth data calculated by stereo vision techniques. Also, our scheme is shown to outperform the well-known TriDef software in terms of human's perceived 3D depth. Based on the implementation by using "OpenMP" parallel programming model, our scheme is capable of executing in real-time on a multi-core CPU platform.

  20. Laser-based direct-write techniques for cell printing

    PubMed Central

    Schiele, Nathan R; Corr, David T; Huang, Yong; Raof, Nurazhani Abdul; Xie, Yubing; Chrisey, Douglas B

    2016-01-01

    Fabrication of cellular constructs with spatial control of cell location (±5 μm) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing. PMID:20814088

  1. 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.

  2. Mg2Si-Based Materials for the Thermoelectric Energy Conversion

    NASA Astrophysics Data System (ADS)

    Cheng, X.; Farahi, N.; Kleinke, H.

    2016-08-01

    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.

  3. Novel fabrication of immunochromatographic assay based on up conversion phosphors for sensitive detection of clenbuterol.

    PubMed

    Wang, Peilong; Wang, Ruiguo; Zhang, Wei; Su, Xiaoou; Luo, Haifeng

    2016-03-15

    A novel and ultra sensitive immunochromatographic assay sensor (ICA) based on up conversion phosphor (UCP) for quantitative detection of clenbuterol (CL) was developed. Monoclonal antibody against CL was labeled with UCP beads. The detection strategy is based on competitive immunoreaction between CL antibodies conjugated to UCP beads and CL or CL antigen on the UCP-ICA sensor. It enables ultra sensitive detection of CL in one single test without complicated sample preparation. Sensing results can be obtained within 10 min. Under optimized conditions, visual limit of detection (vLOD) of UCP-ICA for CL was 0.1 ng/mL. Calculated LOD (cLOD) for CL, as low as 0.01 ng/mL, could be achieved with the UCP-ICA sensor. Recoveries of CL in various sample matrixes ranged from 73.0% to 92.2% and relative standard deviations (RSD) were below 12%. The assay was evaluated with spiked and real samples and the results were compared with liquid chromatography-tandem mass. The developed novel assay method based on UCP could be a potential alternative format for on site and rapid detection of CL as well as other illegal drugs. PMID:26516687

  4. A fuzzy logic based approach to direct load control

    SciTech Connect

    Bhattacharyya, K.; Crow, M.L.

    1996-05-01

    Demand side management programs are strategies designed to alter the shape of the load curve. In order to successfully implement such a strategy, customer acceptance of the program is vital. It is thus desirable to design a model for direct load control which may accommodate customer preferences. This paper presents a methodology for optimizing both customer satisfaction and utility unit commitment savings, based on a fuzzy load model for the direct load control of appliances.

  5. Revisiting Morrison and Osterle 1965: the efficiency of membrane-based electrokinetic energy conversion.

    PubMed

    Catalano, J; Hamelers, H V M; Bentien, A; Biesheuvel, P M

    2016-08-17

    We revisit Morrison and Osterle (1965) who derived a phenomenological expression for the 'figure-of-merit' [Formula: see text] 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 [Formula: see text] derived by Bentien et al (2013). We analyze two physical models for ionic and solvent flow which directly relate [Formula: see text] 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 [Formula: see text] for salt solutions with ions with unequal diffusion coefficients (mobilities) and show that to increase [Formula: see text] the counterion mobility must be low and the coion mobility high. PMID:27321823

  6. 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.

  7. Evidence-based medicine meets goal-directed health care.

    PubMed

    Mold, James W; Hamm, Robert; Scheid, Dewey

    2003-05-01

    Evidence-based medicine and goal-directed, patient-centered health care seem, at times, like parallel universes, though, at a conceptual level, they are perfectly compatible. Part of the problem is that many of the kinds of information required for decision making in primary care are often unavailable or difficult to find. Several case examples are used to illustrate this problem, and reasons and solutions are suggested. The goal-directed health care model could be helpful for directing the search for evidence that is relevant to the decisions that patients and their primary care physicians must make on a regular basis. PMID:12772939

  8. 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

  9. 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

  10. Design and measurements of the absorption section of an up-conversion device based on PbSe quantum-dots

    NASA Astrophysics Data System (ADS)

    Hechster, Elad; Sarusi, Gabby

    2015-12-01

    The absorption section of quantum dots (QD) based night vision devices consists of the OQ sensitizing layer which absorbs the Infrared radiation, the substrate on which the QD are placed, the electrode and, in several cases, a blocking layer that prevents the flow of charge carriers toward the inverse direction. The absorption section plays a dominant role in determining the absorption spectral ranges and the signal-to-noise ratios of the devices. In this work, we show the design of the absorption section of a short wavelength infrared (SWIR) to visible direct up-conversion device. The growth was 300 nm thick PbSe quantum dots (QD) separated by PbSe grain boundaries layer on intrinsic GaAs substrate. Photo-luminescence and absorption measurements suggested that the quantum dots spectral response is blue-shifted to the spectral range in which the up-conversion device is operated i.e., SWIR. We preformed sheet resistance measurements in dark and under illumination that showed that the device exhibits an improvement in the signal-to-noise ratio after annealing ion chloride atmosphere compare with annealing in oxygen atmosphere. These samples have great potential for the use as the absorption section of low-cost, compact, low power consumption, and cooler free up-conversion devices.

  11. Theoretical Study of SOA-Based Wavelength Conversion with NRZ and RZ Format at 40 Gb/s

    NASA Astrophysics Data System (ADS)

    Dong, Jian-Ji; Zhang, Xin-Liang; Fu, Song-Nian; Shum, Ping; Huang, De-Xiu

    2007-04-01

    We theoretically discuss 40 Gb/s semiconductor optical amplifier (SOA)-based wavelength conversion (WC) using a detuning optical bandpass filter based on ultrafast dynamic characteristics of SOA. Both the inverted and non-inverted WCs are obtained by shifting the filter central wavelength with respect to the probe wavelength when input data signal is in return-to-zero (RZ) format. However, we can obtain format conversion from nonreturn-to-zero (NRZ) to pseudo-return-to-zero (PRZ) and inverted WC when the input signal is in NRZ format.

  12. Principal direction-based Hough transform for line detection

    NASA Astrophysics Data System (ADS)

    Zhao, Yao; Pan, Haibin; Du, Changping; Zheng, Yao

    2015-04-01

    A robust and fast line detection method based on Hough transform (HT) is proposed in this paper. Edge pixels are extracted based on the summation and ratio of principal curvatures. Probabilistic sampling on the edge pixels is applied to reduce the count of voting. Then a one-to-one voting strategy is applied by taking advantages of the information of principal direction. The principal direction is also conducive for the successive accurate line segment extraction. The experiments demonstrate that the proposed method shows better locating accuracy and computation efficiency compared with several significant variations of HT.

  13. 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…

  14. 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…

  15. A Directivity Model For Moderate To Large Earthquakes Based On The Direct-Point Parameter

    NASA Astrophysics Data System (ADS)

    Spudich, P.; Chiou, B. S.

    2013-12-01

    We have developed a new model to predict directivity of pseudo-spectral acceleration in the 1- 10 second band for crustal earthquakes of magnitude exceeding 5.7. The model uses a new directivity predictor, the Direct Point Parameter DPP, which, like the Isochrone Directivity Parameter IDP of Spudich and Chiou (2013), is based on isochrone theory but has several advantages over the IDP. The DPP has a stronger theoretical underpinning than IDP has, as it accounts for the radiation pattern of a finite, line source between the hypocenter and the 'direct point', which is a special point located in a zone of higher isochrone velocity than is the IDP ';closest point', (point on the fault closest to the site where ground motions are to be evaluated). The IDP model by contrast uses a point source radiation pattern at the hypocenter. The DPP has smoother spatial variations than does the IDP. It does not depend on the location of the closest point, which can jump discontinuously from one segment of a geometrically complicated fault to another when the target site moves a small distance. Consequently, when using the DPP it is less likely a user's site will unknowingly be on the high or low side of a discontinuity in the predictor. Furthermore, the DPP is easier to calculate than the IDP because 1) the radiation pattern formulae are simpler, 2) it uses a simpler algorithm for handling multi-segment and multi-fault ruptures, and 3) a generalized coordinate transform is no longer necessary for non-planar faults. The directivity model using the DPP is 'narrowband', meaning that the strength of directivity does not rise inexorably with period but rather is maximum at some period that increases with magnitude. The DPP model is the only directivity model explicitly included in one of the NGA-West 2 ground motion prediction equations, namely Chiou and Youngs (2013).

  16. An Isothermal Device Configuration for Diamond Based Photon-Enhanced Thermionic Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Sun, Tianyin; Koeck, Franz; Nemanich, Robert

    2014-03-01

    Diamond can obtain a negative electron affinity (NEA) after hydrogen termination. With NEA and n-type doping, a low effective work function and efficient thermionic emission has been observed from these diamond films. Photo-induced electron emission from nitrogen doped diamond with visible light illumination has also been established by our group. Recently several reports have described efficient energy conversion based on the photon-enhanced thermionic emission (PETE) mechanism. This study proposes a multi-layer emitter and collector structure for an isothermal PETE converter. The emitter structure is based on an n-type NEA diamond film deposited on a p-type Si substrate to enable electron emission across a vacuum gap. In this structure the above-bandgap light is absorbed in the Si and establishs an enhanced electron population for emission through the low work function surface, while sub-bandgap light is absorbed in the collector for transfer to a heat engine. Spectroscopy measurements of the n-type diamond on Si indicate strong electron emissivity with photon illumination, and the emission intensity is significantly increased at elevated temperatures. A simplified model describing the efficiency and performance of an isothermal PETE device is presented. This research is supported through ONR under grant number # N00014-10-1-0540.

  17. 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

    2015-12-01

    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. PMID:26446476

  18. Use of a DBMS (data base management system) to aid in the software conversion process

    SciTech Connect

    Huntley, A.F.; Bryant, R.A.; Buhrmaster, M.A.; Christian, J.L.; Hume, R.

    1987-02-01

    Procedures are described that provide for the automated conversion of a screen library containing over a thousand screen display definitions to a new screen definition software package. The first step is to extract the screen definition information from the original screen package. This information is then loaded into a data base management system (DBMS). The information is manipulated as necessary and output in a format that can be utilized by the new screen package. A major benefit of the procedures developed is that a DBMS allows bulk updates of multiple screen definitions to be performed. Both the source and target screen packages provide only for the updating of individual screens. Although the procedures described apply to the problem of converting screen definitions for a specific application using the two specific screen definition software packages, the flexibility inherent in a DBMS allows its use in solving many such complex problems. The concept can be modified to allow possibilities limited only by the creativity of the DBMS users and the information contained in the data base.

  19. 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. PMID:20057014

  20. 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

  1. Deconvolution based photoacoustic reconstruction for directional transducer with sparsity regularization

    NASA Astrophysics Data System (ADS)

    Moradi, Hamid; Tang, Shuo; Salcudean, Septimiu E.

    2016-03-01

    We define a deconvolution based photoacoustic reconstruction with sparsity regularization (DPARS) algorithm for image restoration from projections. The proposed method is capable of visualizing tissue in the presence of constraints such as the specific directivity of sensors and limited-view Photoacoustic Tomography (PAT). The directivity effect means that our algorithm treats the optically-generated ultrasonic waves based on which direction they arrive at the transducer. Most PA image reconstruction methods assume that sensors have omni-directional response; however, in practice, the sensors show higher sensitivity to the ultrasonic waves coming from one specific direction. In DPARS, the sensitivity of the transducer to incoming waves from different directions are considered. Thus, the DPARS algorithm takes into account the relative location of the absorbers with respect to the transducers, and generates a linear system of equations to solve for the distribution of absorbers. The numerical conditioning and computing times are improved by the use of a sparse Discrete Fourier Transform (DCT) representation of the distribution of absorption coefficients. Our simulation results show that DPARS outperforms the conventional Delay-and-Sum reconstruction method in terms of CNR and RMS errors. Experimental results confirm that DPARS provides images with higher resolution than DAS.

  2. Direct and Highly Selective Conversion of Synthesis Gas into Lower Olefins: Design of a Bifunctional Catalyst Combining Methanol Synthesis and Carbon-Carbon Coupling.

    PubMed

    Cheng, Kang; Gu, Bang; Liu, Xiaoliang; Kang, Jincan; Zhang, Qinghong; Wang, Ye

    2016-04-01

    The direct synthesis of lower (C2 to C4) olefins, key building-block chemicals, from syngas (H2/CO), which can be derived from various nonpetroleum carbon resources, is highly attractive, but the selectivity for lower olefins is low because of the limitation of the Anderson-Schulz-Flory distribution. We report that the coupling of methanol-synthesis and methanol-to-olefins reactions with a bifunctional catalyst can realize the direct conversion of syngas to lower olefins with exceptionally high selectivity. We demonstrate that the choice of two active components and the integration manner of the components are crucial to lower olefin selectivity. The combination of a Zr-Zn binary oxide, which alone shows higher selectivity for methanol and dimethyl ether even at 673 K, and SAPO-34 with decreased acidity offers around 70% selectivity for C2-C4 olefins at about 10% CO conversion. The micro- to nanoscale proximity of the components favors the lower olefin selectivity. PMID:26961855

  3. Giant and broadband circular asymmetric transmission based on two cascading polarization conversion cavities

    NASA Astrophysics Data System (ADS)

    Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Lu, Wei

    2016-04-01

    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.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. Electronic supplementary

  4. Frequency-domain direct waveform inversion based on perturbation theory

    NASA Astrophysics Data System (ADS)

    Kwak, Sangmin; Kim, Youngseo; Shin, Changsoo

    2014-05-01

    A direct waveform inversion based on perturbation theory is proposed to delineate a subsurface velocity structure from seismic data. This technique can directly compute the difference between the actual subsurface velocity and an initial guess of the velocity, while full waveform inversion updates the velocity model in the directions of reducing the data residual. Unlike full waveform inversion using the steepest descent method, the direct waveform inversion does not require a proper step length to iteratively update the velocity model. We present an algorithm for the waveform inversion method in the frequency domain and numerical examples demonstrating how the inversion method can reconstruct subsurface velocity structures using surface seismic data. The time-domain seismograms synthesized in the inversion procedure match the corresponding shot-gather seismograms of field data.

  5. Finger vein recognition based on local directional code.

    PubMed

    Meng, Xianjing; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2012-01-01

    Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade the recognition accuracy, binary pattern based methods are proposed, such as Local Binary Pattern (LBP), Local Derivative Pattern (LDP) and Local Line Binary Pattern (LLBP). However, the rich directional information hidden in the finger vein pattern has not been fully exploited by the existing local patterns. Inspired by the Webber Local Descriptor (WLD), this paper represents a new direction based local descriptor called Local Directional Code (LDC) and applies it to finger vein recognition. In LDC, the local gradient orientation information is coded as an octonary decimal number. Experimental results show that the proposed method using LDC achieves better performance than methods using LLBP. PMID:23202194

  6. Finger Vein Recognition Based on Local Directional Code

    PubMed Central

    Meng, Xianjing; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2012-01-01

    Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade the recognition accuracy, binary pattern based methods are proposed, such as Local Binary Pattern (LBP), Local Derivative Pattern (LDP) and Local Line Binary Pattern (LLBP). However, the rich directional information hidden in the finger vein pattern has not been fully exploited by the existing local patterns. Inspired by the Webber Local Descriptor (WLD), this paper represents a new direction based local descriptor called Local Directional Code (LDC) and applies it to finger vein recognition. In LDC, the local gradient orientation information is coded as an octonary decimal number. Experimental results show that the proposed method using LDC achieves better performance than methods using LLBP. PMID:23202194

  7. Technology-based suicide prevention: current applications and future directions.

    PubMed

    Luxton, David D; June, Jennifer D; Kinn, Julie T

    2011-01-01

    This review reports on current and emerging technologies for suicide prevention. Technology-based programs discussed include interactive educational and social networking Web sites, e-mail outreach, and programs that use mobile devices and texting. We describe innovative applications such as virtual worlds, gaming, and text analysis that are currently being developed and applied to suicide prevention and outreach programs. We also discuss the benefits and limitations of technology-based applications and discuss future directions for their use. PMID:21214382

  8. Directionally solidified eutectic gamma plus beta nickel-base superalloys

    NASA Technical Reports Server (NTRS)

    Jackson, M. R. (Inventor)

    1977-01-01

    A directionally solidified multivariant eutectic gamma + beta nickel-base superalloy casting having improved high temperature strength and oxidation resistance properties is provided. This comprises a two phase eutectic structure containing, on a weight percent basis, 5.0-15.0 tungsten, 8.5-14.5 aluminum, 0.0-35.0 cobalt and the balance being nickel. Embedded within the gamma phase nickel-base matrix are aligned eutectic beta phase (primarily (NiCo)Al reinforcing lamellae.

  9. 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.

  10. 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.

  11. 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. PMID:26692572

  12. Materials considerations for molten salt accelerator-based plutonium conversion systems

    SciTech Connect

    DiStefano, J.R.; DeVan, J.H.; Keiser, J.R.; Klueh, R.L.; Eatherly, W.P.

    1995-03-01

    Accelerator-driven transmutation technology (ADTT) refers to a concept for a system that uses a blanket assembly driven by a source of neutrons produced when high-energy protons from an accelerator strike a heavy metal target. One application for such a system is called Accelerator-Based Plutonium Conversion, or ABC. Currently, the version of this concept being proposed by the Los Alamos National Laboratory features a liquid lead target material and a blanket fuel of molten fluorides that contain plutonium. Thus, the materials to be used in such a system must have, in addition to adequate mechanical strength, corrosion resistance to molten lead, corrosion resistance to molten fluoride salts, and resistance to radiation damage. In this report the corrosion properties of liquid lead and the LiF-BeF{sub 2} molten salt system are reviewed in the context of candidate materials for the above application. Background information has been drawn from extensive past studies. The system operating temperature, type of protective environment, and oxidation potential of the salt are shown to be critical design considerations. Factors such as the generation of fission products and transmutation of salt components also significantly affect corrosion behavior, and procedures for inhibiting their effects are discussed. In view of the potential for extreme conditions relative to neutron fluxes and energies that can occur in an ADTT, a knowledge of radiation effects is a most important factor. Present information for potential materials selections is summarized.

  13. Materials considerations for molten salt accelerator-based plutonium conversion systems

    SciTech Connect

    DiStefano, J.R.; DeVan, J.H.; Keiser, J.R.; Klueh, R.L.; Eatherly, W.P.

    1995-02-01

    Accelerator-driven transmutation technology (ADTT) refers to a concept for a system that uses a blanket assembly driven by a source of neutrons produced when high-energy protons from an accelerator strike a heavy metal target. One application for such a system is called Accelerator-Based Plutonium Conversion, or ABC. Currently, the version of this concept being proposed by the Los Alamos National Laboratory features a liquid lead target material and a blanket fuel of molten fluorides that contain plutonium. Thus, the materials to be used in such a system must have, in addition to adequate mechanical strength, corrosion resistance to molten lead, corrosion resistance to molten fluoride salts, and resistance to radiation damage. In this report the corrosion properties of liquid lead and the LiF-BeF{sub 2} molten salt system are reviewed in the context of candidate materials for the above application. Background information has been drawn from extensive past studies. The system operating temperature, type of protective environment, and oxidation potential of the salt are shown to be critical design considerations. Factors such as the generation of fission products and transmutation of salt components also significantly affect corrosion behavior, and procedures for inhibiting their effects are discussed. In view of the potential for extreme conditions relative to neutron fluxes and energies that can occur in an ADTT, a knowledge of radiation effects is a most important factor. Present information for potential materials selections is summarized.

  14. 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. PMID:27029433

  15. Space-based solar power conversion and delivery systems study. Volume 5: Economic analysis

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Space-based solar power conversion and delivery systems are studied along with a variety of economic and programmatic issues relevant to their development and deployment. The costs, uncertainties and risks associated with the current photovoltaic Satellite Solar Power System (SSPS) configuration, and issues affecting the development of an economically viable SSPS development program are addressed. In particular, the desirability of low earth orbit (LEO) and geosynchronous (GEO) test satellites is examined and critical technology areas are identified. The development of SSPS unit production (nth item), and operation and maintenance cost models suitable for incorporation into a risk assessment (Monte Carlo) model (RAM) are reported. The RAM was then used to evaluate the current SSPS configuration expected costs and cost-risk associated with this configuration. By examining differential costs and cost-risk as a function of postulated technology developments, the critical technologies, that is, those which drive costs and/or cost-risk, are identified. It is shown that the key technology area deals with productivity in space, that is, the ability to fabricate and assemble large structures in space, not, as might be expected, with some hardware component technology.

  16. Light absorption and conversion in solar cell based on Si:O alloy

    NASA Astrophysics Data System (ADS)

    Scapellato, G. G.; Rubino, M.; Crupi, I.; Di Marco, S.; Simone, F.; Mirabella, S.

    2013-08-01

    Thin film Si:O alloys have been grown by plasma enhanced chemical vapor deposition, as intrinsic or highly doped (1 to 5 at. % of B or P dopant) layers. UV-visible/near-infrared spectroscopy revealed a great dependence of the absorption coefficient and of the optical gap (Eg) on the dopant type and concentration, as Eg decreases from 2.1 to 1.9 eV, for the intrinsic or highly p-doped sample, respectively. Thermal annealing up to 400 °C induces a huge H out-diffusion which causes a dramatic absorption increase and a reduction of Eg, down to less than 1.8 eV. A prototypal solar cell has been fabricated using a 400 nm thick, p-i-n structure made of Si:O alloy embedded within flat transparent conductive oxides. Preliminary electrical analyses show a photovoltaic (PV) effect with an open circuit voltage of 0.75 V and a spectral conversion efficiency blue-shifted in comparison to a-Si:H based cell, as expected since the higher Eg in Si:O alloy. These data are presented and discussed, suggesting Si:O alloy as promising material for PV device fabrication.

  17. 3D graphene-based hybrid materials: synthesis and applications in energy storage and conversion.

    PubMed

    Shi, Qiurong; Cha, Younghwan; Song, Yang; Lee, Jung-In; Zhu, Chengzhou; Li, Xiaoyu; Song, Min-Kyu; Du, Dan; Lin, Yuehe

    2016-08-25

    Porous 3D graphene-based hybrid materials (3D GBHMs) are currently attractive nanomaterials employed in the field of energy. Heteroatom-doped 3D graphene and metal, metal oxide, and polymer-decorated 3D graphene with modified electronic and atomic structures provide promising performance as electrode materials in energy storage and conversion. Numerous synthesis methods such as self-assembly, templating, electrochemical deposition, and supercritical CO2, pave the way to mass production of 3D GBHMs in the commercialization of energy devices. This review summarizes recent advances in the fabrication of 3D GBHMs with well-defined architectures such as finely controlled pore sizes, heteroatom doping types and levels. Moreover, current progress toward applications in fuel cells, supercapacitors and batteries employing 3D GBHMs is also highlighted, along with the detailed mechanisms of the enhanced electrochemical performance. Furthermore, current critical issues, challenges and future prospects with respect to applications of 3D GBHMs in practical devices are discussed at the end of this review. PMID:27531643

  18. Topography-based flow-directional roughness: potential and challenges

    NASA Astrophysics Data System (ADS)

    Trevisani, Sebastiano; Cavalli, Marco

    2016-04-01

    Surface texture analysis applied to high-resolution digital terrain models (HRDTMs) is a promising approach for extracting useful fine-scale morphological information. Surface roughness, considered here as a synonym of surface texture, can have a discriminant role in the detection of different geomorphic processes and factors. Very often, the local morphology presents, at different scales, anisotropic characteristics that could be taken into account when calculating or measuring surface roughness. The high morphological detail of HRDTMs permits the description of different aspects of surface roughness, beyond an evaluation limited to isotropic measures of surface roughness. The generalization of the concept of roughness implies the need to refer to a family of specific roughness indices capable of capturing specific multiscale and anisotropic aspects of surface morphology. An interesting set of roughness indices is represented by directional measures of roughness that can be meaningful in the context of analyzed and modeled flow processes. Accordingly, we test the application of a flow-oriented directional measure of roughness based on the geostatistical bivariate index MAD (median of absolute directional differences), which is computed considering surface gravity-driven flow direction. MAD is derived from a modification of a variogram and is specifically designed for the geomorphometric analysis of HRDTMs. The presented approach shows the potential impact of considering directionality in the calculation of roughness indices. The results demonstrate that the use of flow-directional roughness can improve geomorphometric modeling (e.g., sediment connectivity and surface texture modeling) and the interpretation of landscape morphology.

  19. Topography-based flow-directional roughness: potential and challenges

    NASA Astrophysics Data System (ADS)

    Trevisani, S.; Cavalli, M.

    2015-12-01

    Surface texture analysis applied to High Resolution Digital Terrain Models (HRDTMs) is a promising approach for extracting useful fine-scale morphological information. Surface roughness, considered here as a synonym of surface texture, can have a discriminant role in the detection of different geomorphic processes and factors. Very often, the local morphology presents, at different scales, anisotropic characteristics that could be taken into account when calculating or measuring surface roughness. The high morphological detail of HRDTMs permits the description of different aspects of surface roughness, beyond an evaluation limited to isotropic measures of surface roughness. The generalization of the concept of roughness implies the need to refer to a family of specific roughness indices capable of capturing specific multi-scale and anisotropic aspects of surface morphology. An interesting set of roughness indices is represented by directional measures of roughness that can be meaningful in the context of analyzed and modeled flow processes. Accordingly, we test the application of a flow-oriented directional measure of roughness based on the geostatistical bivariate index MAD (median of absolute directional differences), which is computed considering surface gravity-driven flow direction. MAD is derived from a modification of a variogram and is specifically designed for the geomorphometric analysis of HRDTMs. The presented approach shows the potential impact of considering directionality in the calculation of roughness indices. The results demonstrate that the use of flow directional roughness can improve geomorphometric modeling (e.g., sediment connectivity and surface texture modeling) and the interpretation of landscape morphology.

  20. Biocatalytic conversion of methane to methanol as a key step for development of methane-based biorefineries.

    PubMed

    Hwang, In Yeub; Lee, Seung Hwan; Choi, Yoo Seong; Park, Si Jae; Na, Jeong Geol; Chang, In Seop; Kim, Choongik; Kim, Hyun Cheol; Kim, Yong Hwan; Lee, Jin Won; Lee, Eun Yeol

    2014-12-28

    Methane is considered as a next-generation carbon feedstock owing to the vast reserves of natural and shale gas. Methane can be converted to methanol by various methods, which in turn can be used as a starting chemical for the production of value-added chemicals using existing chemical conversion processes. Methane monooxygenase is the key enzyme that catalyzes the addition of oxygen to methane. Methanotrophic bacteria can transform methane to methanol by inhibiting methanol dehydrogenase. In this paper, we review the recent progress made on the biocatalytic conversion of methane to methanol as a key step for methane-based refinery systems and discuss future prospects for this technology. PMID:25223329

  1. Particle flow reconstruction based on the directed tree clustering algorithm

    SciTech Connect

    Chakraborty, D.; Lima, J. G. R.; McIntosh, R.; Zutshi, V.

    2006-10-27

    We present the status of particle flow algorithm development at Northern Illinois University. A key element in our approach is the calorimeter-based directed tree clustering algorithm. We have attempted to identify and tackle the essential challenges and analyze the effect of several different approaches to the reconstruction of jet energies and the Z-boson mass. A number of possibilities have been studied, such as analog vs. digital energy measurement, hit density-based clustering and the use of single or multiple energy thresholds. We plan to use this PFA-based reconstruction to compare some of the proposed detector technologies and geometries.

  2. Quantum Secure Direct Communication Based on Chaos with Authentication

    NASA Astrophysics Data System (ADS)

    Huang, Dazu; Chen, Zhigang; Guo, Ying; Lee, Moon Ho

    2007-12-01

    A quantum secure direct communication protocol based on chaos is proposed with authentication. It has an advantage over distributing the secret message directly and verifying the communicators’ identities with the assistance of a trusted center. To ensure the security of the secret message and the process of verification, the initial order of the travel particles is disturbed according to a chaotic sequence generated secretly via the general Arnold map. Security analysis demonstrates that the present scheme is secure against several attack strategies, such as the man-in-the-middle attack and Trojan horse attack.

  3. Planar metamaterial based on hybridization for directive emission.

    PubMed

    Ourir, Abdelwaheb; Abdeddaim, Redha; de Rosny, Julien

    2012-07-30

    We present the first experimental demonstration of a high-directivity using a mu and epsilon near zero (MENZ) metamaterial. We use the hybridization principles to design a planar MENZ structure based on the fishnet unit cell. Resonant mode engineering achieves an effective permittivity and permeability that approaches zeros around 10.5 GHz simultaneously. We use this metamaterial as a superstrate of a microstrip patch antenna. We show that the directivity of the antenna is effectively enhanced compared to that of the patch antenna alone at the desired frequency. PMID:23038307

  4. The roadmap for low price- high performance IR detector based on LWIR to NIR light up-conversion approach

    NASA Astrophysics Data System (ADS)

    Kipper, R.; Arbel, D.; Baskin, E.; Fayer, A.; Epstein, A.; Shuall, N.; Saguy, A.; Veksler, D.; Spektor, B.; Ben-Aharon, D.; Garber, V.

    2009-05-01

    The introduction of an uncooled microbolometer image sensor about a decade ago enabled cost reduction of IR cameras. As a result, the available markets grew both in military and civilian applications. Since then, the price of microbolometer was gradually reduced due to introduction of devices with smaller pixel, maturity of the technology and quantity growth. However, the requirement for a vacuum package still limits the price of microbolometer based cameras to several thousands of dollars. Sirica's novel wavelength conversion technology aims at breaking this paradigm by being uncooled and vacuumless, lowering IR camera prices by an order of magnitude, opening the way to new mass markets. Sirica's proprietary IR-to-Visible/NIR conversion layer allows for low-cost high performance LWIR detector with no requirement for cooling and vacuum packaging. In the last years, the development efforts focused on development of the conversion media. Recently, a parallel effort for the integration of the conversion layer together with other detector components has started. Packaging of detector components, such as conversion layer, pumping light source, dichroic filter, and their coupling with silicon CMOS image sensor have great importance from a price-performance point of view. According to the company's business-development roadmap, the detector prototype should be available during the first quarter of 2010.

  5. Dynamic X-ray direct conversion detector using a CdTe polycrystalline layer coupled to a CMOS readout chip

    NASA Astrophysics Data System (ADS)

    Arques, Marc; Renet, Sébastien; Brambilla, Andréa; Feuillet, Guy; Gasse, Adrien; Billon-Pierron, Nicolas; Jolliot, Muriel; Mathieu, Lydie; Rohr, Pierre

    2011-05-01

    A direct detection X-ray imager is presented. It uses polycrystalline cadmium telluride (CdTe) grown by close space sublimation technique for the X-ray photoconductor. A 15 mm×15 mm CdTe layer is connected to a 200×200 pixel readout CMOS by indium bumping. X-ray performance at 16 frames/s rate is measured. In particular a readout noise of 0.5 X-ray, an MTF of 50% at 4 lp/mm and a DQE of 20% at 4 lp/mm are obtained.

  6. Graphene-assisted nonlinear optical device for four-wave mixing based tunable wavelength conversion of QPSK signal.

    PubMed

    Hu, Xiao; Zeng, Mengqi; Wang, Andong; Zhu, Long; Fu, Lei; Wang, Jian

    2015-10-01

    We fabricate a nonlinear optical device based on a fiber pigtail cross-section coated with a single-layer graphene grown by chemical vapor deposition (CVD) method. Using such graphene-assisted nonlinear optical device, we experimentally demonstrate tunable wavelength conversion of a 10 Gbaud quadrature phase-shift keying (QPSK) signal by exploiting degenerate four-wave mixing (FWM) progress in graphene. We study the conversion efficiency as functions of the pump power and pump wavelength and evaluate the bit-error rate (BER) performance. The observed optical signal-to-noise ratio (OSNR) penalties for tunable QPSK wavelength conversion are less than 2.2 dB at a BER of 1 × 10(-3). PMID:26480130

  7. pH-Dependent Assembly and Conversions of Six Cadmium(II)-Based Coordination Complexes

    SciTech Connect

    Fang, Hua-Cai; Zhu, Ji-Qin; Zhou, Li-Jiang; Jia, Hong-Yang; Li, Shan-Shan; Gong, Xue; Li, Shu-Bin; Cai, Yue-Peng; Thallapally, Praveen K.; Liu, Jun; Exarhos, Gregory J.

    2010-07-07

    Six cadmium(II) complexes containing N2O2 donor tetradentate asymmetrical Schiff base ligand 2-{[2-(dimethylamino)ethylimino]methyl}-6-methoxyphenol (HL5), namely, [(Cd3L52Cl4)2]•CH3OH•H2O (1), [Cd(L5)Cl]2•CH3OH (2), [Cd2(HL5)Cl4]n (3), {[Cd3(H2L5)2Cl8]•2H2O}n (4), [(H2L5)2]2+•[CdCl4]2-•H2O (5), and [(H2L5)2]2+•[CdCl4]2- (6), have been synthesized using cadmium(II) chloride and asymmetrical Schiff base ligand HL5 under different pH conditions at room temperature. The diverse structures show the marked sensitivity of the structural chemistry of the tetradentate asymmetrical Schiff base ligand HL5. Complex 1 formed at pH = 10 exhibits a rare zero- dimensional structure of trinuclear cadmium (II). At pH = 8-9, a dinuclear cadmium (II) complex 2 is formed. The reaction at pH = 5-7 leads to two one-dimensional structures of 3 and 4. A further decrease of the pH to 3-5 results in a zero-dimensional structure 5. Owing to the departure of lattice water molecules in the crystal, complex 5 at room temperature can gradually undergo single-crystal-to-single-crystal transformation to result complex 6. The results further show that conversions of complex 1 to 5 can also be achieved by adjusting the pH value of the reaction solution, 1→2pH=8→5pH=3 and 3→4pH=5. Comparing these experimental results, it is clear that the pH plays a crucial role in the formation of the resulting structures, which simultaneously provide very effective strategies for constructing the CdII compounds with N2O2 donor tetradentate asymmetrical Schiff base ligand. The strong fluorescent emissions of the six compounds (1-6) make them potentially useful photoactive materials. Furthermore, six Schiff base cadmium complexes (1–6), with DPPH (2,2-dipheny1-1-picrylhydrazy1) as a co-oxidant exhibited the stronger scavenging activity.

  8. Evidence of significant down-conversion in a Si-based solar cell using CuInS{sub 2}/ZnS core shell quantum dots

    SciTech Connect

    Gardelis, Spiros Nassiopoulou, Androula G.

    2014-05-05

    We report on the increase of up to 37.5% in conversion efficiency of a Si-based solar cell after deposition of light-emitting Cd-free, CuInS{sub 2}/ZnS core shell quantum dots on the active area of the cell due to the combined effect of down-conversion and the anti- reflecting property of the dots. We clearly distinguished the effect of down-conversion from anti-reflection and estimated an enhancement of up to 10.5% in the conversion efficiency due to down-conversion.

  9. Directing the public to evidence-based online content.

    PubMed

    Cooper, Crystale Purvis; Gelb, Cynthia A; Vaughn, Alexandra N; Smuland, Jenny; Hughes, Alexandra G; Hawkins, Nikki A

    2015-04-01

    To direct online users searching for gynecologic cancer information to accurate content, the Centers for Disease Control and Prevention's (CDC) 'Inside Knowledge: Get the Facts About Gynecologic Cancer' campaign sponsored search engine advertisements in English and Spanish. From June 2012 to August 2013, advertisements appeared when US Google users entered search terms related to gynecologic cancer. Users who clicked on the advertisements were directed to relevant content on the CDC website. Compared with the 3 months before the initiative (March-May 2012), visits to the CDC web pages linked to the advertisements were 26 times higher after the initiative began (June-August 2012) (p<0.01), and 65 times higher when the search engine advertisements were supplemented with promotion on television and additional websites (September 2012-August 2013) (p<0.01). Search engine advertisements can direct users to evidence-based content at a highly teachable moment--when they are seeking relevant information. PMID:25053580

  10. Quantitative methods to direct exploration based on hydrogeologic information

    USGS Publications Warehouse

    Graettinger, A.J.; Lee, J.; Reeves, H.W.; Dethan, D.

    2006-01-01

    Quantitatively Directed Exploration (QDE) approaches based on information such as model sensitivity, input data covariance and model output covariance are presented. Seven approaches for directing exploration are developed, applied, and evaluated on a synthetic hydrogeologic site. The QDE approaches evaluate input information uncertainty, subsurface model sensitivity and, most importantly, output covariance to identify the next location to sample. Spatial input parameter values and covariances are calculated with the multivariate conditional probability calculation from a limited number of samples. A variogram structure is used during data extrapolation to describe the spatial continuity, or correlation, of subsurface information. Model sensitivity can be determined by perturbing input data and evaluating output response or, as in this work, sensitivities can be programmed directly into an analysis model. Output covariance is calculated by the First-Order Second Moment (FOSM) method, which combines the covariance of input information with model sensitivity. A groundwater flow example, modeled in MODFLOW-2000, is chosen to demonstrate the seven QDE approaches. MODFLOW-2000 is used to obtain the piezometric head and the model sensitivity simultaneously. The seven QDE approaches are evaluated based on the accuracy of the modeled piezometric head after information from a QDE sample is added. For the synthetic site used in this study, the QDE approach that identifies the location of hydraulic conductivity that contributes the most to the overall piezometric head variance proved to be the best method to quantitatively direct exploration. ?? IWA Publishing 2006.

  11. Development of a directional hearing instrument based on array technology.

    PubMed

    Soede, W; Berkhout, A J; Bilsen, F A

    1993-08-01

    A directional hearing aid might be beneficial in reducing background noise in relation to the desired speech signal. Conventional hearing aids with a directional cardioid microphone are insufficient because of the low directivity of cardioids. Research was done to develop microphone(s) with strong directional characteristics using array techniques. Particular emphasis was given to optimization and stability. Free-field simulations of several robust models show that a directivity index of 9 dB can be obtained at the higher frequencies. Simulations were verified with a laboratory model. The results of the measurements show a good agreement with the simulations. Based on simulations and measurements, two portable models were developed and tested with a KEMAR manikin. The KEMAR measurements show that the two models give an improvement of the signal-to-noise ratio of approximately 7.5 dB in a diffuse sound field. It may be concluded that the developed microphones have the capability to reach a significant improvement of speech intelligibility in noise under practical circumstances. PMID:8370885

  12. Bright source of indistinguishable photons based on cavity-enhanced parametric down-conversion utilizing the cluster effect

    NASA Astrophysics Data System (ADS)

    Ahlrichs, Andreas; Benson, Oliver

    2016-01-01

    We present a bright, simple-to-setup, single-mode source of indistinguishable photon pairs at the cesium D1-line with a bandwidth of about 100 MHz. The source is based on degenerate, cavity enhanced spontaneous parametric down-conversion utilizing the cluster effect. The setup relies on a microcontroller-based digital locking system. A brightness of 1.1 ×103/(s m W ) detected, indistinguishable photon pairs could be measured.

  13. Introduction to Solar Photon Conversion

    SciTech Connect

    Nozik, Arthur J; Miller, John

    2010-11-10

    This Thematic Issue on Solar Photon Conversion will provide a review by leading researchers on the present status and prognosis of the science and technology of direct solar photoconversion to electricity and fuels. The topics covered include advanced and novel concepts for low-cost photovoltaic (PV) energy based on chemistry (dye-sensitized photoelectrodes, organic and molecular PV, multiple exciton generation in quantum dots, singlet fission), solar water splitting, redox catalysis for water oxidation and reduction, the role of nanoscience and nanocrystals in solar photoconversion, photoelectrochemical energy conversion, and photoinduced electron transfer.

  14. Feasibility study on AFR-100 fuel conversion from uranium-based fuel to thorium-based fuel

    SciTech Connect

    Heidet, F.; Kim, T.; Grandy, C.

    2012-07-30

    Although thorium has long been considered as an alternative to uranium-based fuels, most of the reactors built to-date have been fueled with uranium-based fuel with the exception of a few reactors. The decision to use uranium-based fuels was initially made based on the technology maturity compared to thorium-based fuels. As a result of this experience, lot of knowledge and data have been accumulated for uranium-based fuels that made it the predominant nuclear fuel type for extant nuclear power. However, following the recent concerns about the extent and availability of uranium resources, thorium-based fuels have regained significant interest worldwide. Thorium is more abundant than uranium and can be readily exploited in many countries and thus is now seen as a possible alternative. As thorium-based fuel technologies mature, fuel conversion from uranium to thorium is expected to become a major interest in both thermal and fast reactors. In this study the feasibility of fuel conversion in a fast reactor is assessed and several possible approaches are proposed. The analyses are performed using the Advanced Fast Reactor (AFR-100) design, a fast reactor core concept recently developed by ANL. The AFR-100 is a small 100 MW{sub e} reactor developed under the US-DOE program relying on innovative fast reactor technologies and advanced structural and cladding materials. It was designed to be inherently safe and offers sufficient margins with respect to the fuel melting temperature and the fuel-cladding eutectic temperature when using U-10Zr binary metal fuel. Thorium-based metal fuel was preferred to other thorium fuel forms because of its higher heavy metal density and it does not need to be alloyed with zirconium to reduce its radiation swelling. The various approaches explored cover the use of pure thorium fuel as well as the use of thorium mixed with transuranics (TRU). Sensitivity studies were performed for the different scenarios envisioned in order to determine the

  15. Secure direct communication based on secret transmitting order of particles

    SciTech Connect

    Zhu Aidong; Zhang Shou; Xia Yan; Fan Qiubo

    2006-02-15

    We propose the schemes of quantum secure direct communication based on a secret transmitting order of particles. In these protocols, the secret transmitting order of particles ensures the security of communication, and no secret messages are leaked even if the communication is interrupted for security. This strategy of security for communication is also generalized to a quantum dialogue. It not only ensures the unconditional security but also improves the efficiency of communication.

  16. The theory of an auto-resonant field emission cathode relativistic electron accelerator for high efficiency microwave to direct current power conversion

    NASA Technical Reports Server (NTRS)

    Manning, Robert M.

    1990-01-01

    A novel method of microwave power conversion to direct current is discussed that relies on a modification of well known resonant linear relativistic electron accelerator techniques. An analysis is presented that shows how, by establishing a 'slow' electromagnetic field in a waveguide, electrons liberated from an array of field emission cathodes, are resonantly accelerated to several times their rest energy, thus establishing an electric current over a large potential difference. Such an approach is not limited to the relatively low frequencies that characterize the operation of rectennas, and can, with appropriate waveguide and slow wave structure design, be employed in the 300 to 600 GHz range where much smaller transmitting and receiving antennas are needed.

  17. The Direct Measurement of Base Drag for Hypersonic Vehicles

    NASA Astrophysics Data System (ADS)

    Lv, Zhi-guo; Li, Guo-jun; Jiang, Hua; Zhao, Rong-juan; Wang, Gang; Huang, Jun

    A new base drag measurement method has been introduced in this paper. In tradition method, the base drag of the model was measured by the pressure transducer located on the bottom of the model. In this method, the base drag was measured with piezoelectric balance directly. The drag force was measured twice by fixing the model base segment to the model or the balance, the difference between these two measurements is considered as the base drag of the model. The wind tunnel test was carried out in φ0.6m shock tunnel of CARDC with a cone model. The base drag of cone model was measured in the flow field of M(=8.42, Re(l=9.67(106/m with the attack angle of 0(. The results showed that the base drag coefficient of the cone model is 0.0015. It means that the base drag can't be ignored in high precision tests, and it can be measured by piezoelectric balance in shock tunnel. The length of the tail sting affects the axis force test result. In the same attack angle, the base drag of high lift/drag ratio model decreases with the increasing of flow field Mach number.

  18. A Flow SPR Immunosensor Based on a Sandwich Direct Method

    PubMed Central

    Tomassetti, Mauro; Conta, Giorgia; Campanella, Luigi; Favero, Gabriele; Sanzò, Gabriella; Mazzei, Franco; Antiochia, Riccarda

    2016-01-01

    In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10−3 and 10−1 M, a measurement time of ≤20 min and a high selectivity both towards β-lactam antibiotics and antibiotics of different classes. PMID:27187486

  19. A Flow SPR Immunosensor Based on a Sandwich Direct Method.

    PubMed

    Tomassetti, Mauro; Conta, Giorgia; Campanella, Luigi; Favero, Gabriele; Sanzò, Gabriella; Mazzei, Franco; Antiochia, Riccarda

    2016-01-01

    In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10(-3) and 10(-1) M, a measurement time of ≤20 min and a high selectivity both towards β-lactam antibiotics and antibiotics of different classes. PMID:27187486

  20. COOH-terminal sequence of the cellular prion protein directs subcellular trafficking and controls conversion into the scrapie isoform

    PubMed Central

    Kaneko, Kiyotoshi; Vey, Martin; Scott, Michael; Pilkuhn, Susanne; Cohen, Fred E.; Prusiner, Stanley B.

    1997-01-01

    Efficient formation of scrapie isoform of prion protein (PrPSc) requires targeting PrPSc by glycophosphatidyl inositol (GPI) anchors to caveolae-like domains (CLDs). Redirecting the cellular isoform of prion protein (PrPC) to clathrin-coated pits by creating chimeric PrP molecules with four different COOH-terminal transmembrane domains prevented the formation of PrPSc. To determine if these COOH-terminal transmembrane segments prevented PrPC from refolding into PrPSc by altering the structure of the polypeptide, we fused the 28-aa COOH termini from the Qa protein. Two COOH-terminal Qa segments differing by a single residue direct the transmembrane protein to clathrin-coated pits or the GPI form to CLDs; PrPSc was formed from GPI-anchored PrPC but not from transmembrane PrPC. Our findings argue that PrPSc formation is restricted to a specific subcellular compartment and as such, it is likely to involve auxiliary macromolecules found within CLDs. PMID:9122195

  1. A study on the flow characteristics of a direct drive turbine for energy conversion generation by experiment and CFD

    NASA Astrophysics Data System (ADS)

    Cho, Y. J.; Zullah, M. A.; Faizal, M.; Choi, Y. D.; Lee, Y. H.

    2012-11-01

    A variety of technologies has been proposed to capture the energy from waves. Some of the more promising designs are undergoing demonstration testing at commercial scales. Due to the complexity of most offshore wave energy devices and their motion response in different sea states, physical tank tests are common practice for WEC design. Full scale tests are also necessary, but are expensive and only considered once the design has been optimized. Computational Fluid Dynamics (CFD) is now recognized as an important complement to traditional physical testing techniques in offshore engineering. Once properly calibrated and validated to the problem, CFD offers a high density of test data and results in a reasonable timescale to assist with design changes and improvements to the device. The purpose of this study is to investigate the performance of a newly developed direct drive hydro turbine (DDT), which will be built in a caisson for extraction of wave energy. Experiments and CFD analysis are conducted to clarify the turbine performance and internal flow characteristics. The results show that commercial CFD code can be applied successfully to the simulation of the wave motion in the water tank. The performance of the turbine for wave energy converter is studied continuously for a ongoing project.

  2. Direct interaction of microtubule- and actin-based transport motors

    NASA Technical Reports Server (NTRS)

    Huang, J. D.; Brady, S. T.; Richards, B. W.; Stenolen, D.; Resau, J. H.; Copeland, N. G.; Jenkins, N. A.

    1999-01-01

    The microtubule network is thought to be used for long-range transport of cellular components in animal cells whereas the actin network is proposed to be used for short-range transport, although the mechanism(s) by which this transport is coordinated is poorly understood. For example, in sea urchins long-range Ca2+-regulated transport of exocytotic vesicles requires a microtubule-based motor, whereas an actin-based motor is used for short-range transport. In neurons, microtubule-based kinesin motor proteins are used for long-range vesicular transport but microtubules do not extend into the neuronal termini, where actin filaments form the cytoskeletal framework, and kinesins are rapidly degraded upon their arrival in neuronal termini, indicating that vesicles may have to be transferred from microtubules to actin tracks to reach their final destination. Here we show that an actin-based vesicle-transport motor, MyoVA, can interact directly with a microtubule-based transport motor, KhcU. As would be expected if these complexes were functional, they also contain kinesin light chains and the localization of MyoVA and KhcU overlaps in the cell. These results indicate that cellular transport is, in part, coordinated through the direct interaction of different motor molecules.

  3. Direct Detection and Sequencing of Damaged DNA Bases

    PubMed Central

    2011-01-01

    Products of various forms of DNA damage have been implicated in a variety of important biological processes, such as aging, neurodegenerative diseases, and cancer. Therefore, there exists great interest to develop methods for interrogating damaged DNA in the context of sequencing. Here, we demonstrate that single-molecule, real-time (SMRT®) DNA sequencing can directly detect damaged DNA bases in the DNA template - as a by-product of the sequencing method - through an analysis of the DNA polymerase kinetics that are altered by the presence of a modified base. We demonstrate the sequencing of several DNA templates containing products of DNA damage, including 8-oxoguanine, 8-oxoadenine, O6-methylguanine, 1-methyladenine, O4-methylthymine, 5-hydroxycytosine, 5-hydroxyuracil, 5-hydroxymethyluracil, or thymine dimers, and show that these base modifications can be readily detected with single-modification resolution and DNA strand specificity. We characterize the distinct kinetic signatures generated by these DNA base modifications. PMID:22185597

  4. Proton exchange membrane fuel cell system diagnosis based on the signed directed graph method

    NASA Astrophysics Data System (ADS)

    Hua, Jianfeng; Lu, Languang; Ouyang, Minggao; Li, Jianqiu; Xu, Liangfei

    The fuel-cell powered bus is becoming the favored choice for electric vehicles because of its extended driving range, zero emissions, and high energy conversion efficiency when compared with battery-operated electric vehicles. In China, a demonstration program for the fuel cell bus fleet operated at the Beijing Olympics in 2008 and the Shanghai Expo in 2010. It is necessary to develop comprehensive proton exchange membrane fuel cell (PEMFC) diagnostic tools to increase the reliability of these systems. It is especially critical for fuel-cell city buses serving large numbers of passengers using public transportation. This paper presents a diagnostic analysis and implementation study based on the signed directed graph (SDG) method for the fuel-cell system. This diagnostic system was successfully implemented in the fuel-cell bus fleet at the Shanghai Expo in 2010.

  5. The Subjective Evaluation Experiments on an Automatic Video Editing System Using Vision-based Head Tracking for Multiparty Conversations

    NASA Astrophysics Data System (ADS)

    Takemae, Yoshinao; Otsuka, Kazuhiro; Yamato, Junji; Ozawa, Shinji

    This paper presents experiments conducted to evaluate an automatic video editing system, founded on vision-based head tracking, that clearly conveys face-to-face multiparty conversations, such as meetings, to viewers. Systems that archive meetings and teleconferences to effectively facilitate human communication are attracting considerable interest. Conventional systems use a fixed-viewpoint camera and simple camera selection based on participants' utterances. Unfortunately, they fail to adequately convey who is talking to whom and nonverbal information about participants etc., to viewers. To solve this problem, we previously proposed an automatic video editing system using vision-based head tracking. This paper describes subjective evaluation experiments in which videos of entire conversations with 3 participants were presented to viewers; the results confirm the effectiveness of our system.

  6. Real-time IP-hologram conversion hardware based on floating point DSPs

    NASA Astrophysics Data System (ADS)

    Oi, Ryutaro; Mishina, Tomoyuki; Yamamoto, Kenji; Okui, Makoto

    2009-02-01

    Holography is a 3-D display method that fully satisfies the visual characteristics of the human eye. However, the hologram must be developed in a darkroom under laser illumination. We attempted hologram generation under white light by adopting an integral photography (IP) technique as the input. In this research, we developed a hardware converter to convert IP input (with 120×66 elemental images) to a hologram with high definition television (HDTV) resolution (approximately 2 million pixels). This conversion could be carried out in real time. In this conversion method, each elemental image can be independently extracted and processed. Our hardware contains twenty 300-MHz floating-point digital signal processors (DSPs) operating in parallel. We verified real-time conversion operations by the implemented hardware.

  7. Full-wave feasibility study of magnetic diagnostic based on O-X mode conversion and oblique reflectometry imaging

    SciTech Connect

    Meneghini, Orso; Choi, Myunghee; Volpe, Francesco

    2014-02-12

    An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and the edge current as a function of the minor radius in the pedestal region. The idea behind such diagnostic is to localize and characterize a direction of reduced reflectivity at the O-mode cutoff layer. We modeled the wave scattering and mode-conversion processes by means of the finite-element COMSOL Multiphysics code in two dimensions (2D). Sensitivity studies were performed for parameters mocking up DIII-D plasmas. Simulations confirmed the presence of a minimum in reflectivity of an externally injected O-mode beam, and confirmed that this minimum depends on the magnetic field at the cutoff, as expected from the OX mode conversion physics. This study gives confidence in the feasibility of the diagnostic.

  8. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 8, July 16--September 30, 1988

    SciTech Connect

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

    1989-03-01

    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 investigated the behavior of some of our catalysts under working conditions using diffuse reflectance fourier transform infrared spectroscopy (DRIFT). Two catalysts (FeRu{sub 3} and Ru{sub 4} on magnesia) were examined under nitrogen, and the Ru{sub 4}/MgO system was examined under a methane/argon mixture. We synthesized ruthenium clusters supported on carbon as catalysts for methane reforming and new phthalocyanines to be used as catalyst precursors for oxidizing methane to methanol. The Ru{sub 4} and FeRu{sub 3} complexes supported on magnesia exhibited very different behavior in the DRIFT cell when heated under nitrogen. The FeRu{sub 3}/MgO system was completely decarbonylated by 400{degrees}C, while spectrum of the Ru{sub 4} system displayed carbonyl peaks until the temperature rose to over 600{degrees}C. The ru{sub 4}/MgO system behaved almost identically under methane/argon as it did under nitrogen in the carbonyl region. In the C-H region of the spectrum (2800-3100 cm{sup {minus}1}), peaks were observed under methane but not under nitrogen. The intensity of these peaks did not vary with temperature. We synthesized new catalysts by supporting the Ru{sub 4} and Ru{sub 6} clusters on carbon. Both acidic zeolites (Type Y or 5A) and basic magnesia (MgO) have been observed to react with hydrocarbons at high temperatures; these reactions generally lead to coking, then deactivation of the catalyst contained on these supports. We expect carbon to be a truly inert support.

  9. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 1, October 16, 1986--January 15, 1987

    SciTech Connect

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

    1987-02-23

    The United States will need to be able to convert coal to liquid fuels should current supplies be interrupted. The indirect method for producing fuel liquids is the gasification of the coal to synthesis gas (syngas) followed by Fischer-Tropsch synthesis to convert syngas to hydrocarbons. However, both the gasifier and the FTS processes result in the production of methane and/or light hydrocarbon by-product that negatively affect the economics of the production of liquid fuel from coal. The goal of SRI`s research is thus 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. SRI project 2678 is exploring two approaches to achieving the stated goal. 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. We will then decompose the organometallic complexes to obtain very stable, highly dispersed catalysts. 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. We will test the catalysts in a fixed-bed isothermal microreactor in a downflow mode at {approximately}100 psi. During the first quarter of this project, we have concentrated on methane oxidation to methanol. We have synthesized phthalocyanine oxidation catalysts containing different metals (Co, Fe, and Ru) within zeolite pores. our examination of their ability to oxidize methane to methanol has indicated preliminary positive results.

  10. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 6, January 16, 1988--April 15, 1988

    SciTech Connect

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

    1988-05-20

    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 synthesized several phthalocyanine catalysts supported on magnesia (MgO) in Task 3. In Task 4 we have tested these catalysts for oxidation of methane and did a number of blank experiments to determine the cause of the low methanol yield we have observed. Magnesia supported catalysts were prepared by first synthesizing the various metal tetrasulfophthalocyanines (TSPCs), converting them to the acid form, and then supporting these complexes on a basic support (MgO) by a neutralization reaction. The metals used were Ru, Pd, Cu, Fe, Co, Mn, and Mo. CoTSPC was also synthesized in zeolite Y using our standard template techniques described in Quarterly Report No. 1. These complexes were examined for catalytic activity in the oxidation of methane. The PdTSPC/MgO had greater activity, and oxidized some of the methane (selectivity of 2.8% from the methane oxidized at 375{degrees}C) to ethane. This is a much lower temperature for this reaction than previously reported in the literature. We also examined the reactivity of various components of the system in the oxidation of the product methanol. The reactor showed some activity for the oxidation of methanol to carbon dioxide. When zeolite or magnesia were added, this activity increased. The magnesia oxidized most of the methanol to carbon dioxide, while the zeolite reduced some of the methanol to hydrocarbons. With oxygen in the feed gas stream (i.e., the conditions of our methane oxidation), a very large fraction of the methanol was oxidized to carbon dioxide when passed over magnesia. From this, we can conclude that any methanol formed in the oxidation of methane would probably be destroyed very quickly on the catalyst bed.

  11. Conversational sensing

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  12. Conversational sensemaking

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Webberley, Will; Braines, Dave

    2015-05-01

    Recent advances in natural language question-answering systems and context-aware mobile apps create opportunities for improved sensemaking in a tactical setting. Users equipped with mobile devices act as both sensors (able to acquire information) and effectors (able to act in situ), operating alone or in collectives. The currently- dominant technical approaches follow either a pull model (e.g. Apple's Siri or IBM's Watson which respond to users' natural language queries) or a push model (e.g. Google's Now which sends notifications to a user based on their context). There is growing recognition that users need more flexible styles of conversational interaction, where they are able to freely ask or tell, be asked or told, seek explanations and clarifications. Ideally such conversations should involve a mix of human and machine agents, able to collaborate in collective sensemaking activities with as few barriers as possible. Desirable capabilities include adding new knowledge, collaboratively building models, invoking specific services, and drawing inferences. As a step towards this goal, we collect evidence from a number of recent pilot studies including natural experiments (e.g. situation awareness in the context of organised protests) and synthetic experiments (e.g. human and machine agents collaborating in information seeking and spot reporting). We identify some principles and areas of future research for "conversational sensemaking".

  13. Magnetic-field-free thermoelectronic power conversion based on graphene and related two-dimensional materials

    NASA Astrophysics Data System (ADS)

    Wanke, R.; Hassink, G. W. J.; Stephanos, C.; Rastegar, I.; Braun, W.; Mannhart, J.

    2016-06-01

    Mobile energy converters require, in addition to high conversion efficiency and low cost, a low mass. We propose to utilize thermoelectronic converters that use 2D-materials such as graphene for their gate electrodes. Deriving the ultimate limit for their specific energy output, we show that the positive energy output is likely close to the fundamental limit for any conversion of heat into electric power. These converters may be valuable as electric power sources of spacecraft, and with the addition of vacuum enclosures, for power generation in electric planes and cars.

  14. 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

    2015-09-01

    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. PMID:26388365

  15. Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 9, October 1--December 31, 1988

    SciTech Connect

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

    1989-03-10

    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 completed our IR spectroscopic examination of the Ru{sub 4}/MgO and FeRu{sub 3}/MgO systems under nitrogen and methane by examining FeRu{sub 3}/MgO under methane. This system behaved quite differently than the same system under nitrogen. Under methane, only one very broad peak is observed at room temperature. Upon heating, the catalyst transformed so that by 300{degrees}C, the spectrum of FeRu{sub 3}/MgO under methane was the same as that of Ru{sub 4}/MgO. This suggests that methane promotes the segregation of the metals in the mixed metal system. The differences in catalytic activity between the FeRu{sub 3}/MgO and Ru{sub 4}/MgO systems may then be due to the presence of IR transparent species such as iron ions which cause different nucleation in the ruthenium clusters. We examined several systems for activity in the methane dehydrogenation reaction. Focusing on systems which produce C{sub 6} hydrocarbons since this is the most useful product. These systems all displayed low activity so that the amount of hydrocarbon product is very low. Some C{sub 6} hydrocarbon is observed over zeolite supports, but its production ceases after the first few hours of reaction. We prepared a new system, Ru{sub 4} supported on carbon, and examined its reactivity. Its activity was very low and in fact the carbon support had the same level of activity. We synthesized four new systems for examination as catalysts in the partial oxidation of methane. Three of these (PtTSPC/MgO, PtTSPC and PdTSPC on carbon) are analogs of PdTSPC/MgO. This system is of interest because we have observed the production of ethane from methane oxidation over PdTSPC/MgO at relatively low temperatures and we wished to explore its generality among close analogs.

  16. Directionally solidified eutectic gamma-gamma nickel-base superalloys

    NASA Technical Reports Server (NTRS)

    Jackson, M. R. (Inventor)

    1977-01-01

    A directionally solidified multivariant eutectic gamma-gamma prime nickel-base superalloy casting having improved high temperature properties was developed. The alloy is comprised of a two phase eutectic structure consisting essentially of on a weight percent base, 6.0 to 9.0 aluminum, 5.0 to 17.0 tantalum, 0-10 cobalt, 0-6 vanadium, 0-6 rhenium, 2.0-6.0 tungsten, and the balance being nickel, subject to the proviso that the sum of the atomic percentages of aluminum plus tantalum is within the range of from 19-22, and the ratio of atomic percentages of tantalum to aluminum plus tantalum is within the range of from 0.12 to 0.23. Embedded within the gamma nickel-base matrix are aligned eutectic gamma prime phase (primarily nickel-aluminum-tantalum) reinforcing fibers.

  17. Potential for GPC-based laser direct writing

    NASA Astrophysics Data System (ADS)

    Bañas, Andrew; Glückstad, Jesper

    2016-04-01

    Generalized Phase Contrast (GPC) is an efficient light shaping method for generating speckle-free contiguous distributions useful in diverse applications such as static beam shaping, optical manipulation or for two-photon excitation in optogenetics. GPC increases the utilization of typical Gaussian lasers for such applications by using phase modulation as opposed to amplitude truncating masks. Here, we explore GPC's potential for increasing the yield of micropscopic 3D printing also known as direct laser writing. Many light based additive manufacturing techniques, adopt a point scanning approach which uses up a lot of time and is prone to roughness in the output. A high-speed layer based approach based on GPC may boost the printing speeds by 10x to 100x, making microscopic 3D printing more practical for industry and manufacture. Such an increase in printing speed would extend its use out of research, and potentially allow advanced lab-produced components in everyday consumer products.

  18. A highly homogeneous nanocoating strategy for Li-rich Mn-based layered oxides based on chemical conversion

    NASA Astrophysics Data System (ADS)

    Ma, Jin; Li, Biao; An, Li; Wei, Hang; Wang, Xiayan; Yu, Pingrong; Xia, Dingguo

    2015-03-01

    Herein, we report a novel strategy for preparing a highly homogeneous nanocoating for Li-rich Mn-based layered oxides by the elemental Al doping followed by chemical conversion in phosphate buffer solution. X-ray photoelectron spectroscopy, soft X-ray absorption spectroscopy and transmission electron microscopy results exhibit that there exist AlPO4 nanocoating on the surface of particles. The resultant AlPO4-nanocoated Li[Li0.2Ni0.11Co0.11Mn0.54Al0.04]O2 particles exhibit a greatly enhanced reversible capacity with superior thermal stabilities in relative to pristine Li[Li0.2Ni0.13Co0.13Mn0.54]O2. Under a current density of 30 mA g-1, the AlPO4-nanocoated Li[Li0.2Ni0.11Co0.11Mn0.54Al0.04]O2 can deliver a specific capacity of 282.1 mAh g-1 with capacity retention of 89% after 35 cycles.

  19. 1982 annual report: Biomass Thermochemical Conversion Program

    SciTech Connect

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1983-01-01

    This report provides a brief overview of the Thermochemical Conversion Program's activities and major accomplishments during fiscal year 1982. The objective of the Biomass Thermochemical Conversion Program is to generate scientific data and fundamental biomass converison process information that, in the long term, could lead to establishment of cost effective processes for conversion of biomass resources into clean fuels and petrochemical substitutes. The goal of the program is to improve the data base for biomass conversion by investigating the fundamental aspects of conversion technologies and exploring those parameters which are critical to these conversion processes. To achieve this objective and goal, the Thermochemical Conversion Program is sponsoring high-risk, long-term research with high payoff potential which industry is not currently sponsoring, nor is likely to support. Thermochemical conversion processes employ elevated temperatures to convert biomass materials into energy. Process examples include: combustion to produce heat, steam, electricity, direct mechanical power; gasification to produce fuel gas or synthesis gases for the production of methanol and hydrocarbon fuels; direct liquefaction to produce heavy oils or distillates; and pyrolysis to produce a mixture of oils, fuel gases, and char. A bibliography of publications for 1982 is included.

  20. Resonant conversion based on GaAs-metal metamaterials within terahertz range

    NASA Astrophysics Data System (ADS)

    Cao, Xiaolong; Che, Yongli; Yao, Jianquan

    2015-07-01

    In this paper, by utilizing the variable conductivity with photo-injection in gallium arsenide (GaAs), we have designed an asymmetrical planar terahertz (THz) metamaterial, which is connected with two single-gap split ring resonator (SRR) by GaAs strip and demonstrated the resonant conversion of SRR within the THz range under appropriate optical pumping. As central trailing arm of the structure, GaAs is skillfully inserted between the two cross arms of the THz metamaterial and plays a key role in resonant conversion. Through modulation of its conductivity (σGaAs), the variable conductivity of GaAs can make one dual-gap SRR into two connective single-gap SRRs in physical structure, at the same time, the state conversion of two different resonances in the THz metamaterial has been achieved. The simulation results show that the resonant states of THz metamaterial can be switched from one LC and one dipole (state 1) to two LC and one new dipole (state 2) through the intermediate state with the increasing σGaAs. This structural design provides a new example to apply variable conductivity to achieve state conversion of resonance and can be extended to the additional application in THz devices.

  1. Improved picture-rate conversion using classification-based LMS-filters

    NASA Astrophysics Data System (ADS)

    An, Le; Heinrich, Adrienne; Cordes, Claus N.; de Haan, Gerard

    2009-01-01

    Due to the recent explosion of multimedia formats and the need to convert between them, more attention is drawn to picture rate conversion. Moreover, growing demands on video motion portrayal without judder or blur requires improved format conversion. The simplest conversion repeats the latest picture until a more recent one becomes available. Advanced methods estimate the motion of moving objects to interpolate their correct position in additional images. Although motion blur and judder have been reduced using motion compensation, artifacts, especially around the moving objects in sequences with fast motion, may be disturbing. Previous work has reduced this so-called 'halo' artifact, but the overall result is still perceived as sub-optimal due to the complexity of the heuristics involved. In this paper, we aim at reducing the heuristics by designing LMS up conversion filters optimized for pre-defined local spatio-temporal image classes. Design and evaluation, and a benchmark with earlier techniques will be discussed. In general, the proposed approach gives better results.

  2. Empirically Based Conversion Factors for Calculating Couple-Years of Protection.

    ERIC Educational Resources Information Center

    Stover, John; Bertrand, Jane T.; Shelton, James D.

    2000-01-01

    Presents conversion factors to be used to translate the quality of the respective contraception methods distributed to a single measure of protection for calculating couple-years of protection in family planning studies. Discusses the implications for the evaluation of family planning programs. (SLD)

  3. A Quantitative Real-Time PCR-Based Strategy for Molecular Evaluation of Nicotine Conversion in Burley Tobacco

    PubMed Central

    Sun, Bo; Xue, Sheng-Ling; Zhang, Fen; Luo, Zhao-Peng; Wu, Ming-Zhu; Chen, Qing; Tang, Hao-Ru; Lin, Fu-Cheng; Yang, Jun

    2015-01-01

    Nornicotine production in Nicotiana tabacum is undesirable because it is the precursor of the carcinogen N′-nitrosonornicotine. In some individual burley tobacco plants, a large proportion of the nicotine can be converted to nornicotine, and this process of nicotine conversion is mediated primarily by enzymatic N-demethylation of nicotine which is controlled mainly by CYP82E4. Here we report a novel strategy based on quantitative real-time polymerase chain reaction (qPCR) method, which analyzed the ratio of nicotine conversion through examining the transcript level of CYP82E4 in burley leaves and do not need ethylene induction before detected. The assay was linear in a range from 1 × 101 to 1 × 105 copies/mL of serially diluted standards, and also showed high specificity and reproducibility (93%–99%). To assess its applicability, 55 plants of burley cultivar Ky8959 at leaf maturing stage were analyzed, and the results were in accordance with those from gas chromatograph-mass spectrometry (GC-MS) method. Moreover, a linear correlation existed between conversion level and CYP82E4 transcript abundance. Taken together, the quantitative real-time PCR assay is standardized, rapid and reproducible for estimation of nicotine conversion level in vivo, which is expected to shed new light on monitoring of burley tobacco converter. PMID:26593897

  4. Simulating the conversion of rural settlements to town land based on multi-agent systems and cellular automata.

    PubMed

    Liu, Yaolin; Kong, Xuesong; Liu, Yanfang; Chen, Yiyun

    2013-01-01

    Rapid urbanization in China has triggered the conversion of land from rural to urban use, particularly the conversion of rural settlements to town land. This conversion is the result of the joint effects of the geographic environment and agents involving the government, investors, and farmers. To understand the dynamic interaction dominated by agents and to predict the future landscape of town expansion, a small town land-planning model is proposed based on the integration of multi-agent systems (MAS) and cellular automata (CA). The MAS-CA model links the decision-making behaviors of agents with the neighbor effect of CA. The interaction rules are projected by analyzing the preference conflicts among agents. To better illustrate the effects of the geographic environment, neighborhood, and agent behavior, a comparative analysis between the CA and MAS-CA models in three different towns is presented, revealing interesting patterns in terms of quantity, spatial characteristics, and the coordinating process. The simulation of rural settlements conversion to town land through modeling agent decision and human-environment interaction is very useful for understanding the mechanisms of rural-urban land-use change in developing countries. This process can assist town planners in formulating appropriate development plans. PMID:24244472

  5. Simulating the Conversion of Rural Settlements to Town Land Based on Multi-Agent Systems and Cellular Automata

    PubMed Central

    Liu, Yaolin; Kong, Xuesong; Liu, Yanfang; Chen, Yiyun

    2013-01-01

    Rapid urbanization in China has triggered the conversion of land from rural to urban use, particularly the conversion of rural settlements to town land. This conversion is the result of the joint effects of the geographic environment and agents involving the government, investors, and farmers. To understand the dynamic interaction dominated by agents and to predict the future landscape of town expansion, a small town land-planning model is proposed based on the integration of multi-agent systems (MAS) and cellular automata (CA). The MAS-CA model links the decision-making behaviors of agents with the neighbor effect of CA. The interaction rules are projected by analyzing the preference conflicts among agents. To better illustrate the effects of the geographic environment, neighborhood, and agent behavior, a comparative analysis between the CA and MAS-CA models in three different towns is presented, revealing interesting patterns in terms of quantity, spatial characteristics, and the coordinating process. The simulation of rural settlements conversion to town land through modeling agent decision and human-environment interaction is very useful for understanding the mechanisms of rural-urban land-use change in developing countries. This process can assist town planners in formulating appropriate development plans. PMID:24244472

  6. Efficient LUT-Based Truncated Multiplier and Its Application in RGB to YCbCr Color Space Conversion

    NASA Astrophysics Data System (ADS)

    Hoang, Van-Phuc; Pham, Cong-Kha

    High performance, low area multipliers are highly desired for modern and future DSP systems due to the increasing demand of high speed DSP applications. In this paper, we present an efficient architecture for an LUT-based truncated multiplier and its application in RGB to YCbCr color space conversion which can be used for digital TV, image and video processing systems. By employing an improved split LUT-based architecture and LUT optimization method, the proposed multiplier can reduce the value of area-delay product by up to 52% compared with other constant multiplier methods. The FPGA implementation of a color space conversion application employing the proposed multiplier also results in significant reduction of area-delay product of up to 48%.

  7. Direct generation of 2-ps blue pulses from gain-switched InGaN VCSEL assessed by up-conversion technique

    PubMed Central

    Asahara, Akifumi; Chen, Shaoqiang; Ito, Takashi; Yoshita, Masahiro; Liu, Wenjie; Zhang, Baoping; Suemoto, Tohru; Akiyama, Hidefumi

    2014-01-01

    Ultra-short pulses in blue region generated from compact and low-cost semiconductor lasers have attracted much attention for a wide variety of applications. Nitride-based vertical-cavity surface-emitting lasers (VCSELs), having intrinsic high material gain and short cavities, favor the generation of ultra-short blue pulses via a simple gain-switching technique. In this study, we fabricated a single-mode InGaN VCSEL consisting of 10-period InGaN/GaN quantum wells (QWs). The output pulses were evaluated accurately with an up-conversion measurement system having time resolution of 0.12 ps. We demonstrated that ultra-short blue pulses, as short as 2.2 ps at 3.4 K and 4.0 ps at room temperature, were generated from the gain-switched InGaN VCSEL via impulsive optical pumping, without any post-processing. The gain-switched pulses we obtained should greatly promote the development of ultra-short blue pulse generation. In addition, this successful assessment demonstrates the up-conversion technique's usefulness for characterizing ultra-short blue pulses from semiconductor lasers. PMID:25236162

  8. Direct generation of 2-ps blue pulses from gain-switched InGaN VCSEL assessed by up-conversion technique.

    PubMed

    Asahara, Akifumi; Chen, Shaoqiang; Ito, Takashi; Yoshita, Masahiro; Liu, Wenjie; Zhang, Baoping; Suemoto, Tohru; Akiyama, Hidefumi

    2014-01-01

    Ultra-short pulses in blue region generated from compact and low-cost semiconductor lasers have attracted much attention for a wide variety of applications. Nitride-based vertical-cavity surface-emitting lasers (VCSELs), having intrinsic high material gain and short cavities, favor the generation of ultra-short blue pulses via a simple gain-switching technique. In this study, we fabricated a single-mode InGaN VCSEL consisting of 10-period InGaN/GaN quantum wells (QWs). The output pulses were evaluated accurately with an up-conversion measurement system having time resolution of 0.12 ps. We demonstrated that ultra-short blue pulses, as short as 2.2 ps at 3.4 K and 4.0 ps at room temperature, were generated from the gain-switched InGaN VCSEL via impulsive optical pumping, without any post-processing. The gain-switched pulses we obtained should greatly promote the development of ultra-short blue pulse generation. In addition, this successful assessment demonstrates the up-conversion technique's usefulness for characterizing ultra-short blue pulses from semiconductor lasers. PMID:25236162

  9. Modeling creep behavior in a directionally solidified nickel base superalloy

    NASA Astrophysics Data System (ADS)

    Ibanez, Alejandro R.

    Directionally solidified (DS) nickel-base superalloys provide significant improvements relative to the limitations inherent to equiaxed materials in the areas of creep resistance, oxidation, and low and high cycle fatigue resistance. Since these materials are being pushed to the limits of their capability in gas turbine applications, accurate mathematical models are needed to predict the service lives of the hot-section components to prevent unscheduled outages due to sudden mechanical failures. The objectives of this study are to perform critical experiments and investigate the high temperature tensile, fracture toughness, creep deformation, creep rupture and creep crack growth behavior of DS GTD111 as well as to apply creep deformation, rupture and crack growth models that will enable the accurate representation of the life times of the DS GTD111 superalloy gas turbine components that are exposed to high temperatures under sustained tensile stresses. The applied models will be capable of accurately representing the creep deformation, rupture and crack growth behavior as a function of stress, time and temperature. The yield strength and fracture toughness behavior with temperature is governed by the gamma particles. The longitudinal direction showed higher ductility and strength than the transverse direction. The TL direction exhibited higher fracture toughness than the LT orientation because the crack follows a more tortuous path. The longitudinal direction showed higher creep ductility, lower minimum strain rates and longer creep rupture times than the transverse direction. The results in the transverse direction were similar to the ones for the equiaxed version of this superalloy. Two models for creep deformation have been evaluated. The power-law model includes a secondary and a tertiary creep term with the primary creep represented by a constant. A theta-projection model has also been evaluated and it appears to provide a more accurate representation of creep

  10. Carbon-Nanohorn Based Nanofluids for a Direct Absorption Solar Collector for Civil Application.

    PubMed

    Moradi, A; Sani, E; Simonetti, M; Francini, F; Chiavazzo, E; Asinari, P

    2015-05-01

    Direct solar absorption has been often considered in the past as a possible solution for solar thermal collectors for residential and small commercial applications. A direct absorption could indeed improve the performance of solar collectors by skipping one step of the heat transfer mechanism in standard devices and having a more convenient temperature distribution inside the collector. Classical solar thermal collectors have a metal sheet as absorber, designed such that water has the minimum temperature in each transversal section, in order to collect as much solar thermal energy as possible. On the other hand, in a direct configuration, the hottest part of the system is the operating fluid and this allows to have a more efficient conversion. Nanofluids, i.e., fluids with a suspension of nanoparticles, such as carbon nanohorns, could be a good and innovative family of absorbing fluids owing to their higher absorption coefficient compared to the base fluid and stability under moderate temperature gradients. Moreover, carbon nanohorns offer the remarkable advantage of a reduced toxicity over other carbon nanoparticles. In this work, a three-dimensional model of the absorption phenomena in nanofluids within a cylindrical tube is coupled with a computational fluid dynamics (CFD) analysis of the flow and temperature field. Measured optical properties of nanofluids at different concentrations have been implemented in the model. Heat losses due to conduction, convection and radiation at the boundaries are considered as well. PMID:26504968

  11. Catalytic conversion of furfural into a 2,5-furandicarboxylic acid-based polyester with total carbon utilization.

    PubMed

    Pan, Tao; Deng, Jin; Xu, Qing; Zuo, Yong; Guo, Qing-Xiang; Fu, Yao

    2013-01-01

    One divided into two combined into one: The catalytic conversion of furfural into a 2,5-furandicarboxylic acid-based polyester, linked by the disproportionation of furoate to furan and 2,5-furandicarboxylate, is reported. In this manner, all carbons are utilized, demonstrating the success of combining a platform molecule from C(5) sugars (furfural) to one from C(6) sugars (2,5-FDCA). PMID:23239596

  12. Advancing understanding of microbial bioenergy conversion processes by activity-based protein profiling

    SciTech Connect

    Liu, Yun; Fredrickson, James K.; Sadler, Natalie C.; Nandhikonda, Premchendar; Smith, Richard D.; Wright, Aaron T.

    2015-09-25

    Here, the development of renewable biofuels is a global priority, but success will require novel technologies that greatly improve our understanding of microbial systems biology. An approach with great promise in enabling functional characterization of microbes is activity-based protein profiling (ABPP), which employs chemical probes to directly measure enzyme function in discrete enzyme classes in vivo and/or in vitro, thereby facilitating the rapid discovery of new biocatalysts and enabling much improved biofuel production platforms. We review general design strategies in ABPP, and highlight recent advances that are or could be pivotal to biofuels processes including applications of ABPP to cellulosic bioethanol, biodiesel, and phototrophic production of hydrocarbons. We also examine the key challenges and opportunities of ABPP in renewable biofuels research. The integration of ABPP with molecular and systems biology approaches will shed new insight on the catalytic and regulatory mechanisms of functional enzymes and their synergistic effects in the field of biofuels production.

  13. Low Bandgap InAs-Based Thermophotovoltaic Cells for Heat-Electricity Conversion

    NASA Astrophysics Data System (ADS)

    Krier, A.; Yin, M.; Marshall, A. R. J.; Krier, S. E.

    2016-02-01

    The practical realization of thermophotovoltaic (TPV) cells, which can directly convert heat into electric power, is of considerable technological interest. However, most existing TPV cells require heat sources at temperatures of ˜1800°C. Here we report a low bandgap mid-infrared cell based on InAs and demonstrate TPV operation with heat sources at temperatures in the range 500-950°C. The maximum open circuit voltage (V oc) and short circuit current density (J sc) were measured as 0.06 V and 0.89 A cm-2 for a blackbody temperature of 950°C and an incident power density of 720 mW cm-2 without antireflection coating or electrode optimisation. TPV operation was obtained with heat sources at temperatures as low as 500°C, which represents progress towards energy scavenging and waste heat recovery applications.

  14. Low Bandgap InAs-Based Thermophotovoltaic Cells for Heat-Electricity Conversion

    NASA Astrophysics Data System (ADS)

    Krier, A.; Yin, M.; Marshall, A. R. J.; Krier, S. E.

    2016-06-01

    The practical realization of thermophotovoltaic (TPV) cells, which can directly convert heat into electric power, is of considerable technological interest. However, most existing TPV cells require heat sources at temperatures of ˜1800°C. Here we report a low bandgap mid-infrared cell based on InAs and demonstrate TPV operation with heat sources at temperatures in the range 500-950°C. The maximum open circuit voltage ( V oc) and short circuit current density ( J sc) were measured as 0.06 V and 0.89 A cm-2 for a blackbody temperature of 950°C and an incident power density of 720 mW cm-2 without antireflection coating or electrode optimisation. TPV operation was obtained with heat sources at temperatures as low as 500°C, which represents progress towards energy scavenging and waste heat recovery applications.

  15. An ultrathin directional carpet cloak based on generalized Snell's law

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Lei Mei, Zhong; Ru Zhang, Wan; Yang, Fan; Jun Cui, Tie

    2013-10-01

    Based on generalized Snell's law, we propose an ultrathin directional carpet cloak operating in the reflection geometry. The cloak is constructed by two identical ultrathin metal-backed dielectric slabs with metallic "H" patterns on the other sides to form a triangular region. When put on an infinite ground plane and illuminated by electromagnetic waves from overhead, it can manipulate the reflected wavefronts to mimic the infinite ground plane. We fabricate a microwave sample and perform near-field scanning experiments to verify the cloaking effect. The measurement results are in good agreement with full-wave simulations and theoretical analysis.

  16. Direct Isosurface Ray Casting of NURBS-Based Isogeometric Analysis.

    PubMed

    Schollmeyer, Andre; Froehlich, Bernd

    2014-09-01

    In NURBS-based isogeometric analysis, the basis functions of a 3D model's geometric description also form the basis for the solution space of variational formulations of partial differential equations. In order to visualize the results of a NURBS-based isogeometric analysis, we developed a novel GPU-based multi-pass isosurface visualization technique which performs directly on an equivalent rational Bézier representation without the need for discretization or approximation. Our approach utilizes rasterization to generate a list of intervals along the ray that each potentially contain boundary or isosurface intersections. Depth-sorting this list for each ray allows us to proceed in front-to-back order and enables early ray termination. We detect multiple intersections of a ray with the higher-order surface of the model using a sampling-based root-isolation method. The model's surfaces and the isosurfaces always appear smooth, independent of the zoom level due to our pixel-precise processing scheme. Our adaptive sampling strategy minimizes costs for point evaluations and intersection computations. The implementation shows that the proposed approach interactively visualizes volume meshes containing hundreds of thousands of Bézier elements on current graphics hardware. A comparison to a GPU-based ray casting implementation using spatial data structures indicates that our approach generally performs significantly faster while being more accurate. PMID:26357373

  17. Reliability analysis based on a direct ship hull strength assessment

    NASA Astrophysics Data System (ADS)

    Feng, Guoqing; Wang, Dongsheng; Garbatov, Yordan; Guedes Soares, C.

    2015-12-01

    A method of reliability analysis based on a direct strength calculation employing the von Mises stress failure criterion is presented here. The short term strain distributions of ship hull structural components are identified through the statistical analysis of the wave-induced strain history and the long term distributions by the weighted summation of the short term strain distributions. The wave-induced long term strain distribution is combined with the still water strain. The extreme strain distribution of the response strain is obtained by statistical analysis of the combined strains. The limit state function of the reliability analysis is based on the von Mises stress failure criterion, including the related uncertainties due to the quality of the material and model uncertainty. The reliability index is calculated using FORM and sensitivity analysis of each variable that has effects on the reliability is also discussed.

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

    SciTech Connect

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

    2016-01-01

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

  19. [Contributions by Conversation Analysis to healthcare studies: reflections based on patients' attributions].

    PubMed

    Ostermann, Ana Cristina; de Souza, Joseane

    2009-07-01

    This study is part of a larger research project aimed at investigating physician-patient interactions in women's health. In this article, by looking at naturalistic data, which consists of 144 fully transcribed audio recordings of face-to-face interactions between gynecologists/obstetricians and female patients, we propose to: (1) present the theoretical and methodological approach of Conversation Analysis to health studies in Brazil; (2) discuss how Conversation Analysis can reveal how 'macro' questions (e.g. National Policy for the Humanization of Healthcare) are (or are not) translated into interactional practices at the 'micro' level and, thus, emphasize the issues of language and communication, only briefly discussed in the HumanizaSUS documents; and (3) analyze how a specific interactional phenomenon, 'attribution' (i.e. voluntary explanations about the possible causes of their problems), might describe ordinary and concrete humanization practices in healthcare services. PMID:19578573

  20. A space-based combined thermophotovoltaic electric generator and gas laser solar energy conversion system

    NASA Technical Reports Server (NTRS)

    Yesil, Oktay

    1989-01-01

    This paper describes a spaceborne energy conversion system consisting of a thermophotovoltaic electric generator and a gas laser. As a power source for the converson, the system utilizes an intermediate blackbody cavity heated to a temperature of 2000-2400 K by concentrated solar radiation. A double-layer solar cell of GaAs and Si forms a cylindrical surface concentric to this blackbody cavity, receiving the blackbody radiation and converting it into electricity with cell conversion efficiency of 50 percent or more. If the blackbody cavity encloses a laser medium, the blackbody radiation can also be used to simultaneously pump a lasing gas. The feasibility of blackbody optical pumping at 4.3 microns in a CO2-He gas mixture was experimentally demonstrated.

  1. PbSe nanocrystal-based infrared-to-visible up-conversion device.

    PubMed

    Kim, Do Young; Choudhury, Kaushik Roy; Lee, Jae Woong; Song, Dong Woo; Sarasqueta, Galileo; So, Franky

    2011-05-11

    Low-cost hybrid up-conversion devices with infrared sensitivity to 1.5 μm were obtained by integrating a colloidal PbSe nanocrystal near-infrared sensitizing layer on a green phosphorescent organic light emitting diode. A ZnO nanocrystal hole blocking layer is incorporated in the devices for keeping the device off in the absence of IR excitation. The maximum photon (1.3 μm)-to-photon (0.52 μm) conversion efficiency is 1.3%. The extension (until 1.5 μm) of the near-infrared wavelengths, which can be converted to visible light, may be able to improve night vision. PMID:21504192

  2. Dual lithium insertion and conversion mechanisms in a titanium-based mixed-anion nanocomposite.

    PubMed

    Dambournet, Damien; Chapman, Karena W; Chupas, Peter J; Gerald, Rex E; Penin, Nicolas; Labrugere, Christine; Demourgues, Alain; Tressaud, Alain; Amine, Khalil

    2011-08-31

    The electrochemical reaction of lithium with a vacancy-containing titanium hydroxyfluoride was studied. On the basis of pair distribution function analysis, NMR, and X-ray photoelectron spectroscopy, we propose that the material undergoes partitioning upon initial discharge to form a nanostructured composite containing crystalline Li(x)TiO(2), surrounded by a Ti(0) and LiF layer. The Ti(0) is reoxidized upon reversible charging to an amorphous TiF(3) phase via a conversion reaction. The crystalline Li(x)TiO(2) is involved in an insertion reaction. The resulting composite electrode, Ti(0)-LiF/Li(x)TiO(2) ⇔ TiF(3)/ Li(y)TiO(2), allows reaction of more than one Li per Ti, providing a route to higher capacities while improving the energy efficiency compared to pure conversion chemistries. PMID:21809881

  3. Planet Diversity Yields with Space-based Direct Imaging Telescopes

    NASA Astrophysics Data System (ADS)

    Domagal-Goldman, Shawn; Kopparapu, Ravi Kumar; Hébrard, Eric; Stark, Chris; Robinson, Tyler D.; Roberge, Aki; Mandell, Avi; McElwain, Michael W.; Clampin, Mark; Meadows, Victoria; Arney, Giada; Advanced Technology Large Aperture Space Telescope Science Team, Exoplanet Climate Group

    2016-01-01

    In this presentation, we will estimate the yield for a diversity of planets from future space-based flagship telescopes. We first divvy up planets into categories that are based on current observables, and that should impact the spectra we hope to observe in the future. The two main classification parameters we use here are the size of a planet and the energy flux into the planet's atmosphere. These two parameters are measureable or inferable from present-day observations, and should have a strong influence on future spectroscopy observations from JWST, WFIRST (with a coronagraph and/or starshade), and concept flagship missions that would fly some time after WFIRST. This allows us to calculate "ηplanet" values for each kind of planet. These η values then allow calculations of the expected yields from direct imaging missions, by leveraging the models and prior work by Stark and colleagues (2014, 2015). That work estimated the yields for potentially Earth-like worlds (i.e. of a size and stellar irradiation consistent with definitions of the habitable zone) for telescopes with a variety of observational parameters. We will do the same thing here, but for a wider variety of planets. This will allow us to discuss the implications of architecture and instrument properties on the diversity of worlds that future direct imaging missions would observe.

  4. Optimization of a motor learning attention-directing strategy based on an individual's motor imagery ability.

    PubMed

    Sakurada, Takeshi; Hirai, Masahiro; Watanabe, Eiju

    2016-01-01

    Motor learning performance has been shown to be affected by various cognitive factors such as the focus of attention and motor imagery ability. Most previous studies on motor learning have shown that directing the attention of participants externally, such as on the outcome of an assigned body movement, can be more effective than directing their attention internally, such as on body movement itself. However, to the best of our knowledge, no findings have been reported on the effect of the focus of attention selected according to the motor imagery ability of an individual on motor learning performance. We measured individual motor imagery ability assessed by the Movement Imagery Questionnaire and classified the participants into kinesthetic-dominant (n = 12) and visual-dominant (n = 8) groups based on the questionnaire score. Subsequently, the participants performed a motor learning task such as tracing a trajectory using visuomotor rotation. When the participants were required to direct their attention internally, the after-effects of the learning task in the kinesthetic-dominant group were significantly greater than those in the visual-dominant group. Conversely, when the participants were required to direct their attention externally, the after-effects of the visual-dominant group were significantly greater than those of the kinesthetic-dominant group. Furthermore, we found a significant positive correlation between the size of after-effects and the modality-dominance of motor imagery. These results suggest that a suitable attention strategy based on the intrinsic motor imagery ability of an individual can improve performance during motor learning tasks. PMID:26466828

  5. Delamination detection in composite laminates using dispersion change based on mode conversion of Lamb waves

    NASA Astrophysics Data System (ADS)

    Okabe, Yoji; Fujibayashi, Keiji; Shimazaki, Mamoru; Soejima, Hideki; Ogisu, Toshimichi

    2010-11-01

    A new ultrasonic propagation system has been constructed using macrofiber composite (MFC) actuators and fiber Bragg grating (FBG) sensors. The MFCs and FBGs can be integrated into composite laminates because of their small size and high fracture strain. The developed system can send and receive broadband Lamb waves. In this research, this system was used to detect delamination damage in composite laminates. First, the multiple modes of Lamb waves in a carbon-fiber-reinforced plastic (CFRP) quasi-isotropic laminate were identified by transmitting and receiving the symmetric and antisymmetric modes separately. Then, the mode conversions at both tips of a delamination were investigated through an experiment and a two-dimensional finite element analysis (FEA). A new delamination detection method was proposed on the basis of the mode conversions, and experiments were carried out on laminates with an artificial delamination. When antisymmetric modes were excited, the frequency dispersion of the received A1 mode changed, depending on the delamination length owing to the mode conversion between the A1 mode and the S0 mode. This phenomenon was confirmed through the FEA and these results prove that this new method is effective in detecting a delamination in CFRP laminates.

  6. A new high definition zoom method based on compounded direct pixel beamforming for medical ultrasound imaging: preliminary results

    NASA Astrophysics Data System (ADS)

    Yoon, Sungsoo; Lee, Jongpil; Chang, Jin Ho; Song, Tai-Kyong; Yoo, Yangmo

    2013-03-01

    Conventional ultrasound imaging based on scan conversion suffers from blurring artifacts caused by interpolation[1]. Especially, when zooming an image for enlarging lesions during scan conversion (i.e., read-zoom), this blurring artifact becomes severe. To reduce blurring artifacts, a write-zoom method was previously proposed. However, it still presents blurring artifacts and lowers the frame rate due to increased line density. In this paper, a new high definition zoom method based on compounded direct pixel beamforming (CDPB) capable enhancing the detail and boundary of lesions is presented. The performance of the proposed method was evaluated with phantom and in vivo experiments by measuring the information entropy contrast (IEC). The radio-frequency channel data were acquired by using a 3.5-MHz convex array transducer with the SonixTouch research platform (Ultrasonix Medical Corp., Vancouver, BC, Canada). The enlarged images using a new high-definition zoom method based on CDPB (i.e., HDZ-CDPB) with 128 transmit scanlines were reconstructed along with read- and write zoom (RZ and WZ) images based on scan conversion by using 128 and 256 transmit scanlines, respectively. From the phantom experiments, the IEC value with the proposed HDZCDPB method was enhanced by maximally 42% and 29% compared to the RZ and WZ methods, respectively. This preliminary results indicate that the proposed HDZ-CDPB method would be useful for generating a high definition ultrasound zoom image with improved image quality compared to the conventional scan conversion based methods (i.e., RZ and WZ) while achieving the high frame rate.

  7. Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

    SciTech Connect

    Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; Vaudin, Mark D.; Skrtic, Drago; Antonucci, Joseph M.; Hoffman, Kathleen M.; Giuseppetti, Anthony A.; Ilavsky, Jan

    2014-07-28

    Our objective was to investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials. Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to local structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significantly, for the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified.

  8. Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

    DOE PAGESBeta

    Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; Vaudin, Mark D.; Skrtic, Drago; Antonucci, Joseph M.; Hoffman, Kathleen M.; Giuseppetti, Anthony A.; Ilavsky, Jan

    2014-07-28

    Our objective was to investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials. Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to localmore » structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significantly, for the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified.« less

  9. Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

    PubMed Central

    Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; Vaudin, Mark D.; Skrtic, Drago; Antonucci, Joseph M.; Hoffman, Kathleen M.; Giuseppetti, Anthony A.; Ilavsky, Jan

    2014-01-01

    Objective To investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP) -to-apatite transition in ACP based dental composite materials. Methods Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. Results We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to local structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significance For the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified. PMID:25082155

  10. Directed light fabrication of iron-based materials

    SciTech Connect

    Thoma, D.J.; Charbon, C.; Lewis, G.K.; Nemec, R.B.

    1995-01-01

    Directed light fabrication (DLF) is a process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, 3-dimensional metal components. From a computer generated solid model, deposition ``tool paths`` are constructed that command the laser movement to fabricate near net shape parts a layer at a time. Among potential candidate systems to study, iron-based alloys are particularly attractive for rapid prototyping. To evaluate the processing parameters in the DLF process, studies have been performed on the microstructural development in 1-dimensional and 2-dimensional Fe-based components. For example, continuous microstructural features are evident, implying a continuous liquid/solid interface during processing. In addition, solidification cooling rates have been determined based upon secondary dendrite arm spacings in Fe-25wt. % Ni and 316 stainless steel. Cooling rates vary from 10{sup 1}{minus}10{sup 5} K s{sup {minus}1}, and the solidification behavior has been simulated using macroscopic heat transfer analyses.

  11. Demosaicing Based on Directional Difference Regression and Efficient Regression Priors.

    PubMed

    Wu, Jiqing; Timofte, Radu; Van Gool, Luc

    2016-08-01

    Color demosaicing is a key image processing step aiming to reconstruct the missing pixels from a recorded raw image. On the one hand, numerous interpolation methods focusing on spatial-spectral correlations have been proved very efficient, whereas they yield a poor image quality and strong visible artifacts. On the other hand, optimization strategies, such as learned simultaneous sparse coding and sparsity and adaptive principal component analysis-based algorithms, were shown to greatly improve image quality compared with that delivered by interpolation methods, but unfortunately are computationally heavy. In this paper, we propose efficient regression priors as a novel, fast post-processing algorithm that learns the regression priors offline from training data. We also propose an independent efficient demosaicing algorithm based on directional difference regression, and introduce its enhanced version based on fused regression. We achieve an image quality comparable to that of the state-of-the-art methods for three benchmarks, while being order(s) of magnitude faster. PMID:27254866

  12. A novel Retinex algorithm based on alternating direction optimization

    NASA Astrophysics Data System (ADS)

    Fu, Xueyang; Lin, Qin; Guo, Wei; Huang, Yue; Zeng, Delu; Ding, Xinghao

    2013-10-01

    The goal of the Retinex theory is to removed the effects of illumination from the observed images. To address this typical ill-posed inverse problem, many existing Retinex algorithms obtain an enhanced image by using different assumptions either on the illumination or on the reflectance. One significant limitation of these Retinex algorithms is that if the assumption is false, the result is unsatisfactory. In this paper, we firstly build a Retinex model which includes two variables: the illumination and the reflectance. We propose an efficient and effective algorithm based on alternating direction optimization to solve this problem where FFT (Fast Fourier Transform) is used to speed up the computation. Comparing with most existing Retinex algorithms, the proposed method solve the illumination image and reflectance image without converting images to the logarithmic domain. One of the advantages in this paper is that, unlike other traditional Retinex algorithms, our method can simultaneously estimate the illumination image and the reflectance image, the later of which is the ideal image without the illumination effect. Since our method can directly separate the illumination and the reflectance, and the two variables constrain each other mutually in the computing process, the result is robust to some degree. Another advantage is that our method has less computational cost and can be applied to real-time processing.

  13. A new root-based direction-finding algorithm

    NASA Astrophysics Data System (ADS)

    Wasylkiwskyj, Wasyl; Kopriva, Ivica; DoroslovačKi, Miloš; Zaghloul, Amir I.

    2007-04-01

    Polynomial rooting direction-finding (DF) algorithms are a computationally efficient alternative to search-based DF algorithms and are particularly suitable for uniform linear arrays of physically identical elements provided that mutual interaction among the array elements can be either neglected or compensated for. A popular algorithm in such situations is Root Multiple Signal Classification (Root MUSIC (RM)), wherein the estimation of the directions of arrivals (DOA) requires the computation of the roots of a (2N - 2) -order polynomial, where N represents number of array elements. The DOA are estimated from the L pairs of roots closest to the unit circle, where L represents number of sources. In this paper we derive a modified root polynomial (MRP) algorithm requiring the calculation of only L roots in order to estimate the L DOA. We evaluate the performance of the MRP algorithm numerically and show that it is as accurate as the RM algorithm but with a significantly simpler algebraic structure. In order to demonstrate that the theoretically predicted performance can be achieved in an experimental setting, a decoupled array is emulated in hardware using phase shifters. The results are in excellent agreement with theory.

  14. A deep space power system option based on synergistic power conversion technologies

    NASA Astrophysics Data System (ADS)

    Schreiber, Jeffrey G.

    2000-01-01

    Deep space science missions have typically used radioisotope thermoelectric generator (RTG) power systems. The RTG power system has proven itself to be a rugged and highly reliable power system over many missions, however, the thermal-to-electric conversion technology used was approximately 5% efficient. While the relatively low efficiency has some benefits in terms of system integration, there are compelling reasons why a more efficient conversion system should be pursued. The cost savings alone that are available as a result of the reduced isotope inventory are significant. The Advanced Radioisotope Power System (ARPS) project was established to fulfill this goal. Although it was not part of the ARPS project, Stirling conversion technology was being demonstrated with a low level of funding by both NASA and DOE. A power system with Stirling convertors, although intended for use with an isotope heat source, can be combined with other advanced technologies to provide a novel power system for deep space missions. An inflatable primary concentrator would be used in combination with a refractive secondary concentrator (RSC) as the heat source to power the system. The inflatable technology as a structure has made great progress for a variety of potential applications such as communications reflectors, radiators and solar arrays. The RSC has been pursued for use in solar thermal propulsion applications, and it's unique properties allow some advantageous system trades to be made. The power system proposed would completely eliminate the isotope heat source and could potentially provide power for science missions to planets as distant as Uranus. This paper will present the background and developmental status of the technologies and will then describe the power system being proposed. .

  15. A Deep Space Power System Option Based on Synergistic Power Conversion Technologies

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    2000-01-01

    Deep space science missions have typically used radioisotope thermoelectric generator (RTG) power systems. The RTG power system has proven itself to be a rugged and highly reliable power system over many missions, however the thermal-to-electric conversion technology used was approximately 5% efficient. While the relatively low efficiency has some benefits in terms of system integration, there are compelling reasons why a more efficient conversion system should be pursued. The cost savings alone that are available as a result of the reduced isotope inventory are significant. The Advanced Radioisotope Power System (ARPS) project was established to fulfill this goal. Although it was not part of the ARPS project, Stirling conversion technology is being demonstrated with a low level of funding by both NASA and DOE. A power system with Stirling convertors. although intended for use with an isotope heat source. can be combined with other advanced technologies to provide a novel power system for deep space missions. An inflatable primary concentrator would be used in combination with a refractive secondary concentrator (RSC) as the heat source to power the system. The inflatable technology as a structure has made great progress for a variety of potential applications such as communications reflectors, radiators and solar arrays. The RSC has been pursued for use in solar thermal propulsion applications, and it's unique properties allow some advantageous system trades to be made. The power system proposed would completely eliminate the isotope heat source and could potentially provide power for science missions to planets as distant as Uranus. This paper will present the background and developmental status of the technologies and will then describe the power system being proposed.

  16. Advancing understanding of microbial bioenergy conversion processes by activity-based protein profiling

    DOE PAGESBeta

    Liu, Yun; Fredrickson, James K.; Sadler, Natalie C.; Nandhikonda, Premchendar; Smith, Richard D.; Wright, Aaron T.

    2015-09-25

    Here, the development of renewable biofuels is a global priority, but success will require novel technologies that greatly improve our understanding of microbial systems biology. An approach with great promise in enabling functional characterization of microbes is activity-based protein profiling (ABPP), which employs chemical probes to directly measure enzyme function in discrete enzyme classes in vivo and/or in vitro, thereby facilitating the rapid discovery of new biocatalysts and enabling much improved biofuel production platforms. We review general design strategies in ABPP, and highlight recent advances that are or could be pivotal to biofuels processes including applications of ABPP to cellulosicmore » bioethanol, biodiesel, and phototrophic production of hydrocarbons. We also examine the key challenges and opportunities of ABPP in renewable biofuels research. The integration of ABPP with molecular and systems biology approaches will shed new insight on the catalytic and regulatory mechanisms of functional enzymes and their synergistic effects in the field of biofuels production.« less

  17. The Usefulness of Three-Dimensional Angiography with a Flat Panel Detector of Direct Conversion Type in a Transcatheter Arterial Chemoembolization Procedure for Hepatocellular Carcinoma: Initial Experience

    SciTech Connect

    Kakeda, Shingo Korogi, Yukunori; Hatakeyama, Yoshihisa; Ohnari, Norihiro; Oda, Nobuhiro; Nishino, Kazuyoshi; Miyamoto, Wataru

    2008-03-15

    The purpose of this study was to assess the usefulness of a three-dimensional (3D) angiography system using a flat panel detector of direct conversion type in treatments with subsegmental transcatheter arterial chemoembolization (TACE) for hepatocellular carcinomas (HCCs). Thirty-six consecutive patients who underwent hepatic angiography were prospectively examined. First, two radiologists evaluated the degree of visualization of the peripheral branches of the hepatic arteries on 3D digital subtraction angiography (DSA). Then the radiologists evaluated the visualization of tumor staining and feeding arteries in 25 patients (30 HCCs) who underwent subsegmental TACE. The two radiologists who performed the TACE assessed whether the additional information provided by 3D DSA was useful for treatments. In 34 (94.4%) of 36 patients, the subsegmental branches of the hepatic arteries were sufficiently visualized. The feeding arteries of HCCs were sufficiently visualized in 28 (93%) of 30 HCCs, whereas tumor stains were sufficiently visualized in 18 (60%). Maximum intensity projection images were significantly superior to volume recording images for visualization of the tumor staining and feeding arteries of HCCs. In 27 (90%) of 30 HCCs, 3D DSA provided additional useful information for subsegmental TACE. The high-quality 3D DSA with flat panel detector angiography system provided a precise vascular road map, which was useful for performing subsegmental TACE .of HCCs.

  18. Spectral optimization of the color temperature tunable white light-emitting diode (LED) cluster consisting of direct-emission blue and red LEDs and a diphosphor conversion LED.

    PubMed

    Zhong, Ping; He, Guoxing; Zhang, Minhao

    2012-09-10

    The correlated color temperature (CCT) tunable white-light LED cluster, which consists of direct-emission blue and red LEDs as well as phosphor-conversion (PC) LEDs packaged by combining green and orange phosphors with a blue LED die, has been obtained by nonlinear program for maximizing luminous efficacy (LE) of radiation (LER) under conditions of both color rendering index (CRI) and special CRI of R9 for strong red above 90 at CCTs of 2700 K to 6500 K. The optimal peak wavelengths of blue LED, red LED, blue LED die, green and orange phosphors are 465 nm, 628 nm, 452 nm, 530 nm and 586 nm, respectively. The real CCT tunable PC/red/blue LED cluster with CRIs of 90~96, R9s of 90~96, CQSs of 89~94, LERs of 303~358 lm/W, and LEs of 105~119 lm/W has been realized at CCTs of 2722 K to 6464 K. The deviation of the peak wavelength should be less than ± 5 nm for blue LED die, ± 1 nm for red LED, and ± 2 nm for blue LED to achieve the PC/R/B LED cluster with high optical performance. PMID:23037535

  19. Lipidomic and transcriptomic analyses of Chlamydomonas reinhardtii under heat stress unveil a direct route for the conversion of membrane lipids into storage lipids.

    PubMed

    Légeret, B; Schulz-Raffelt, M; Nguyen, H M; Auroy, P; Beisson, F; Peltier, G; Blanc, G; Li-Beisson, Y

    2016-04-01

    Studying how photosynthetic cells modify membrane lipids in response to heat stress is important to understand how plants and microalgae adapt to daily fluctuations in temperature and to investigate new lipid pathways. Here, we investigate changes occurring in lipid molecular species and lipid metabolism genes during early response to heat stress in the model photosynthetic microorganism Chlamydomonas reinhardtii. Lipid molecular species analyses revealed that, after 60 min at 42 °C, a strong decrease in specific polyunsaturated membrane lipids was observed together with an increase in polyunsaturated triacylglycerols (TAGs) and diacylglycerols (DAGs). The fact that decrease in the major chloroplastic monogalactosyldiacylglycerol sn1-18:3/sn2-16:4 was mirrored by an accumulation of DAG sn1-18:3/sn2-16:4 and TAG sn1-18:3/sn2-16:4/sn3-18:3 indicated that newly accumulated TAGs were formed via direct conversion of monogalactosyldiacylglycerols to DAGs then TAGs. Lipidomic analyses showed that the third fatty acid of a TAG likely originated from a phosphatidylethanolamine or a diacylglyceryl-O-4'-(N,N,N,-trimethyl)-homoserine betaine lipid species. Candidate genes for this TAG synthesis pathway were provided through comparative transcriptomic analysis and included a phospholipase A2 homolog and the DAG acyltransferase DGTT1. This study gives insights into the molecular events underlying changes in membrane lipids during heat stress and reveals an alternative route for TAG synthesis. PMID:26477535

  20. A marine direction finding system based on global positioning system

    NASA Astrophysics Data System (ADS)

    Dǎnişor, Alin; Izet-Ünsalan, Kunsel-Özel; Ünsalan, Deniz; Tamaş, Razvan; Dǎnişor, Cosmin

    2015-02-01

    Direction finding and attitude determination is of utmost importance for marine, aerial, spatial and land-based navigation [1], as well as control of vehicles, in surveying and in target acquisition of tracking radars. These problems can be solved using dedicated sensors commonly named as compasses and rate gyros. Unfortunately, the classical means of attitude determination both by magnetic and gyrocompasses become unusable at extreme latitudes. Furthermore, gyrocompasses inherently yield erroneous results on high speed craft. Three-axis attitude of a vehicle can be determined using a GPS receiver with multiple antennas, by measuring carrier phases [2], signal strength [3], or integrated INS/GPS systems [4]. This paper proposes a new method of attitude determination using two low-cost GPS receivers.

  1. MEM: A physical-based directional meteoroid model

    NASA Technical Reports Server (NTRS)

    McNamara, H.; Cooke, W.; Suggs, R.

    2004-01-01

    Three years of research conducted by the University of Western Ontario into the nature and distribution of the sporadic sources have been incorporated into a Meteoroid Engineering Model (MEM) by members of the Meteoroid Environments Office at NASA's Marshall Space Flight Center. This paper gives a broad overview of this model, new features of which include: a) identification of the sporadic radiants with real sources of meteoroids, such as comets, b) a physics-based approach which yields accurate fluxes and directionality for interplanetary spacecraft anywhere from 0.2 AU to 2 AU. and c) velocity distributions obtained from theory and validated against observation. Its use and application is also described, along with existing limitations and plans for future improvements.

  2. High power density reactors based on direct cooled particle beds

    SciTech Connect

    Powell, J.R.; Horn, F.L.

    1985-01-01

    Reactors based on direct cooled HTGR type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out long the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBR's) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed. 12 figs.

  3. Novel optical directional coupler based on surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Zhao, Huawei; Guang, Xu Guang; Huang, Jingtang

    2008-09-01

    In this paper, finite difference time domain (FDTD) method and perfect matching layer (PML) absorbing boundary condition are adopted to simulate and analyze a novel optical directional coupler (ODC) based on surface plasmon polaritons (SPPs). Transmittance at each output port of the novel ODC with different coupling region lengths shows it follows the general regulations of a conventional ODC. Especially, its transverse size is of nanoscale. The extreme power position offset between the two output ports is proved to be connected with the real part of Ag's complex refractive index. The excess loss and isolation of the ODC are, respectively, 0.57 and 25.9 dB for 1550 nm telecommunication wavelength, when the length of the coupling region equals half of its coupling length.

  4. Catalytic conversion of syngas to mixed alcohols over Zn-Mn promoted Cu-Fe based catalyst

    DOE PAGESBeta

    Lu, Yongwu; Yu, Fei; Hu, Jin; Liu, Jian

    2012-04-12

    Zn-Mn promoted Cu-Fe based catalyst was synthesized by the co-precipitation method. Mixed alcohols synthesis from syngas was studied in a half-inch tubular reactor system after the catalyst was reduced. Zn-Mn promoted Cu-Fe based catalyst was characterized by SEM-EDS, TEM, XRD, and XPS. The liquid phase products (alcohol phase and hydrocarbon phase) were analyzed by GC-MS and the gas phase products were analyzed by GC. The results showed that Zn-Mn promoted Cu-Fe based catalyst had high catalytic activity and high alcohol selectivity. The maximal CO conversion rate was 72%, and the yield of alcohol and hydrocarbons were also very high. Cumore » (111) was the active site for mixed alcohols synthesis, Fe2C (101) was the active site for olefin and paraffin synthesis. The reaction mechanism of mixed alcohols synthesis from syngas over Zn-Mn promoted Cu-Fe based catalyst was proposed. Here, Zn-Mn promoted Cu-Fe based catalyst can be regarded as a potential candidate for catalytic conversion of biomass-derived syngas to mixed alcohols.« less

  5. Catalytic conversion of syngas to mixed alcohols over Zn-Mn promoted Cu-Fe based catalyst

    SciTech Connect

    Lu, Yongwu; Yu, Fei; Hu, Jin; Liu, Jian

    2012-04-12

    Zn-Mn promoted Cu-Fe based catalyst was synthesized by the co-precipitation method. Mixed alcohols synthesis from syngas was studied in a half-inch tubular reactor system after the catalyst was reduced. Zn-Mn promoted Cu-Fe based catalyst was characterized by SEM-EDS, TEM, XRD, and XPS. The liquid phase products (alcohol phase and hydrocarbon phase) were analyzed by GC-MS and the gas phase products were analyzed by GC. The results showed that Zn-Mn promoted Cu-Fe based catalyst had high catalytic activity and high alcohol selectivity. The maximal CO conversion rate was 72%, and the yield of alcohol and hydrocarbons were also very high. Cu (111) was the active site for mixed alcohols synthesis, Fe2C (101) was the active site for olefin and paraffin synthesis. The reaction mechanism of mixed alcohols synthesis from syngas over Zn-Mn promoted Cu-Fe based catalyst was proposed. Here, Zn-Mn promoted Cu-Fe based catalyst can be regarded as a potential candidate for catalytic conversion of biomass-derived syngas to mixed alcohols.

  6. Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

    PubMed

    Bikson, Marom; Grossman, Pnina; Thomas, Chris; Zannou, Adantchede Louis; Jiang, Jimmy; Adnan, Tatheer; Mourdoukoutas, Antonios P; Kronberg, Greg; Truong, Dennis; Boggio, Paulo; Brunoni, André R; Charvet, Leigh; Fregni, Felipe; Fritsch, Brita; Gillick, Bernadette; Hamilton, Roy H; Hampstead, Benjamin M; Jankord, Ryan; Kirton, Adam; Knotkova, Helena; Liebetanz, David; Liu, Anli; Loo, Colleen; Nitsche, Michael A; Reis, Janine; Richardson, Jessica D; Rotenberg, Alexander; Turkeltaub, Peter E; Woods, Adam J

    2016-01-01

    This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. Safety data from animal tests for tissue damage are reviewed with systematic consideration of translation to humans. Arbitrary safety considerations are avoided. Computational models are used to relate dose to brain exposure in humans and animals. We review relevant dose-response curves and dose metrics (e.g. current, duration, current density, charge, charge density) for meaningful safety standards. Special consideration is given to theoretically vulnerable populations including children and the elderly, subjects with mood disorders, epilepsy, stroke, implants, and home users. Evidence from relevant animal models indicates that brain injury by Direct Current Stimulation (DCS) occurs at predicted brain current densities (6.3-13 A/m(2)) that are over an order of magnitude above those produced by conventional tDCS. To date, the use of conventional tDCS protocols in human trials (≤40 min, ≤4 milliamperes, ≤7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations. PMID:27372845

  7. A flexoelectricity effect-based sensor for direct torque measurement

    NASA Astrophysics Data System (ADS)

    Zhang, Shuwen; Xu, Minglong; Liu, Kaiyuan; Shen, Shengping

    2015-12-01

    In this study, a direct torque sensor based on the flexoelectricity generated by un-polarized polyvinylidene fluoride (PVDF) via electromechanical coupling is developed as a novel torque measurement mechanism that does not require external electric power excitation. The sensing method is developed based on the shear strain gradient and the shear flexoelectric response of PVDF. A theoretical analysis is primarily presented for the design of the sensing structure. Then the structure of the PVDF sensing module is discussed and designed. The radius ratio of the sensing module is defined and then discussed according to the load, the strain gradient, the electrode area and the general electric charge output. The finite element method is used to analyze the mechanical properties of the designed PVDF sensing module. Then the theoretical sensitivity of the sensor is predicated as 0.9441 pC Nm-1. The experiment system setup is developed, and the sensing properties of the measurement mechanism are tested at frequencies of 0.5 Hz, 1 Hz, 1.5 Hz and 2 Hz using identical modules. The measurement range of the designed sensor is 0-1.68 Nm and the average sensitivity is measured as 0.8950 pC Nm-1. The experimental results agree well with the theoretically predicted results. These results prove that the torque sensing method based on un-polarized PVDF is suitable for measurement of dynamic torque loads with a flexoelectricity-based mechanism. When using this method, external electric power excitation of the sensing module is no longer required.

  8. All digital monolithic scanning readout based on Sigma-Delta analog to digital conversion

    NASA Astrophysics Data System (ADS)

    Mandl, William; Rutschow, Carl

    1992-07-01

    It is generally accepted that sensor systems can benefit from some form of on-focal-plane A/D conversion in terms of overall system noise improvement. The issue of whether or not the Delta-Sigma modulation process can be applied to the development of an approach using conventional A/D converters or cryogenic circuit materials is addressed from the standpoint of the scanning focal plane. Each pixel row of the scanning sensor is treated as a continuous analog signal source with a fixed signal bandwidth. By allocating a Delta-Sigma converter per sensor pixel row, theory predicts the oversample rate required to achieve the designed conversion resolution. The Delta-Sigma consists of two major parts. The modulator, which samples the analog input and develops a corresponding digital bit stream, and the digital signal processor, which compresses the bit stream into the Nyquist rate multibit codes and performs noise filtering, are described. Only the modulator needs to be on the focal plane since its output is digital. This reduces the development problem to one of fitting the modulator only into the allocated space and power budget per sensor.

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

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.; Sawicki, Jerzy T.

    2003-01-01

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

  10. Fundamental Discovery of New Phases and Direct Conversion of Carbon into Diamond and hBN into cBN and Properties

    NASA Astrophysics Data System (ADS)

    Narayan, Jagdish; Bhaumik, Anagh

    2016-04-01

    We review the discovery of new phases of carbon (Q-carbon) and BN (Q-BN) and address critical issues related to direct conversion of carbon into diamond and hBN into cBN at ambient temperatures and pressures in air without any need for catalyst and the presence of hydrogen. The Q-carbon and Q-BN are formed as a result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram ( P vs T) of carbon, and show that by rapid quenching, kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. Similarly, the hBN-cBN-Liquid triple point is shifted from 3500 K/9.5 GPa to as low as 2800 K and atmospheric pressure. It is shown that nanosecond laser heating of amorphous carbon and nanocrystalline BN on sapphire, glass, and polymer substrates can be confined to melt in a super undercooled state. By quenching this super undercooled state, we have created a new state of carbon (Q-carbon) and BN (Q-BN) from which nanocrystals, microcrystals, nanoneedles, microneedles, and thin films are formed depending upon the nucleation and growth times allowed and the presence of growth template. The large-area epitaxial diamond and cBN films are formed, when appropriate planar matching or lattice matching template is provided for growth from super undercooled liquid. The Q-phases have unique atomic structure and bonding characteristics as determined by high-resolution SEM and backscatter diffraction, HRTEM, STEM-Z, EELS, and Raman spectroscopy, and exhibit new and improved mechanical hardness, electrical conductivity, and chemical and physical properties, including room-temperature ferromagnetism and enhanced field emission. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g-1. We have also deposited diamond on cBN by using a novel

  11. TU-F-18C-02: Increasing Amorphous Selenium Thickness in Direct Conversion Flat-Panel Imagers for Contrast-Enhanced Dual-Energy Breast Imaging

    SciTech Connect

    Scaduto, DA; Hu, Y-H; Zhao, W

    2014-06-15

    Purpose: Contrast-enhanced (CE) breast imaging using iodinated contrast agents requires imaging with x-ray spectra at energies greater than those used in mammography. Optimizing amorphous selenium (a-Se) flat panel imagers (FPI) for this higher energy range may increase lesion conspicuity. Methods: We compare imaging performance of a conventional FPI with 200 μm a-Se conversion layer to a prototype FPI with 300 μm a-Se layer. Both detectors are evaluated in a Siemens MAMMOMAT Inspiration prototype digital breast tomosynthesis (DBT) system using low-energy (W/Rh 28 kVp) and high-energy (W/Cu 49 kVp) x-ray spectra. Detectability of iodinated lesions in dual-energy images is evaluated using an iodine contrast phantom. Effects of beam obliquity are investigated in projection and reconstructed images using different reconstruction methods. The ideal observer signal-to-noise ratio is used as a figure-of-merit to predict the optimal a-Se thickness for CE lesion detectability without compromising conventional full-field digital mammography (FFDM) and DBT performance. Results: Increasing a-Se thickness from 200 μm to 300 μm preserves imaging performance at typical mammographic energies (e.g. W/Rh 28 kVp), and improves the detective quantum efficiency (DQE) for high energy (W/Cu 49 kVp) by 30%. While the more penetrating high-energy x-ray photons increase geometric blur due to beam obliquity in the FPI with thicker a-Se layer, the effect on lesion detectability in FBP reconstructions is negligible due to the reconstruction filters employed. Ideal observer SNR for CE objects shows improvements in in-plane detectability with increasing a-Se thicknesses, though small lesion detectability begins to degrade in oblique projections for a-Se thickness above 500 μm. Conclusion: Increasing a-Se thickness in direct conversion FPI from 200 μm to 300 μm improves lesion detectability in CE breast imaging with virtually no cost to conventional FFDM and DBT. This work was partially

  12. Optimizing legacy molecular dynamics software with directive-based offload

    SciTech Connect

    Michael Brown, W.; Carrillo, Jan-Michael Y.; Gavhane, Nitin; Thakkar, Foram M.; Plimpton, Steven J.

    2015-05-14

    The directive-based programming models are one solution for exploiting many-core coprocessors to increase simulation rates in molecular dynamics. They offer the potential to reduce code complexity with offload models that can selectively target computations to run on the CPU, the coprocessor, or both. In our paper, we describe modifications to the LAMMPS molecular dynamics code to enable concurrent calculations on a CPU and coprocessor. We also demonstrate that standard molecular dynamics algorithms can run efficiently on both the CPU and an x86-based coprocessor using the same subroutines. As a consequence, we demonstrate that code optimizations for the coprocessor also result in speedups on the CPU; in extreme cases up to 4.7X. We provide results for LAMMAS benchmarks and for production molecular dynamics simulations using the Stampede hybrid supercomputer with both Intel (R) Xeon Phi (TM) coprocessors and NVIDIA GPUs: The optimizations presented have increased simulation rates by over 2X for organic molecules and over 7X for liquid crystals on Stampede. The optimizations are available as part of the "Intel package" supplied with LAMMPS. (C) 2015 Elsevier B.V. All rights reserved.

  13. Optimizing legacy molecular dynamics software with directive-based offload

    DOE PAGESBeta

    Michael Brown, W.; Carrillo, Jan-Michael Y.; Gavhane, Nitin; Thakkar, Foram M.; Plimpton, Steven J.

    2015-05-14

    The directive-based programming models are one solution for exploiting many-core coprocessors to increase simulation rates in molecular dynamics. They offer the potential to reduce code complexity with offload models that can selectively target computations to run on the CPU, the coprocessor, or both. In our paper, we describe modifications to the LAMMPS molecular dynamics code to enable concurrent calculations on a CPU and coprocessor. We also demonstrate that standard molecular dynamics algorithms can run efficiently on both the CPU and an x86-based coprocessor using the same subroutines. As a consequence, we demonstrate that code optimizations for the coprocessor also resultmore » in speedups on the CPU; in extreme cases up to 4.7X. We provide results for LAMMAS benchmarks and for production molecular dynamics simulations using the Stampede hybrid supercomputer with both Intel (R) Xeon Phi (TM) coprocessors and NVIDIA GPUs: The optimizations presented have increased simulation rates by over 2X for organic molecules and over 7X for liquid crystals on Stampede. The optimizations are available as part of the "Intel package" supplied with LAMMPS. (C) 2015 Elsevier B.V. All rights reserved.« less

  14. Optimizing legacy molecular dynamics software with directive-based offload

    NASA Astrophysics Data System (ADS)

    Michael Brown, W.; Carrillo, Jan-Michael Y.; Gavhane, Nitin; Thakkar, Foram M.; Plimpton, Steven J.

    2015-10-01

    Directive-based programming models are one solution for exploiting many-core coprocessors to increase simulation rates in molecular dynamics. They offer the potential to reduce code complexity with offload models that can selectively target computations to run on the CPU, the coprocessor, or both. In this paper, we describe modifications to the LAMMPS molecular dynamics code to enable concurrent calculations on a CPU and coprocessor. We demonstrate that standard molecular dynamics algorithms can run efficiently on both the CPU and an x86-based coprocessor using the same subroutines. As a consequence, we demonstrate that code optimizations for the coprocessor also result in speedups on the CPU; in extreme cases up to 4.7X. We provide results for LAMMPS benchmarks and for production molecular dynamics simulations using the Stampede hybrid supercomputer with both Intel®  Xeon Phi™ coprocessors and NVIDIA GPUs. The optimizations presented have increased simulation rates by over 2X for organic molecules and over 7X for liquid crystals on Stampede. The optimizations are available as part of the "Intel package" supplied with LAMMPS.

  15. Graphene-based terahertz tunable plasmonic directional coupler

    SciTech Connect

    He, Meng-Dong Wang, Kai-Jun; Wang, Lei; Li, Jian-Bo; Liu, Jian-Qiang; Huang, Zhen-Rong; Wang, Lingling; Wang, Lin; Hu, Wei-Da; Chen, Xiaoshuang

    2014-08-25

    We propose and numerically analyze a terahertz tunable plasmonic directional coupler which is composed of a thin metal film with a nanoscale slit, dielectric grating, a graphene sheet, and a dielectric substrate. The slit is employed to generate surface plasmon polaritons (SPPs), and the metal-dielectric grating-graphene-dielectric constructs a Bragg reflector, whose bandgap can be tuned over a wide frequency range by a small change in the Fermi energy level of graphene. As a graphene-based Bragg reflector is formed on one side of the slit, the structure enables SPP waves to be unidirectionally excited on the other side of the slit due to SPP interference, and the SPP waves in the Bragg reflector can be efficiently switched on and off by tuning the graphene's Fermi energy level. By introducing two optimized graphene-based Bragg reflectors into opposite sides of the slit, SPP waves can be guided to different Bragg reflectors at different Fermi energy levels, thus achieving a tunable bidirectional coupler.

  16. Chemical and structural analyses of subsurface crevices formed during spontaneous deposition of cerium-based conversion coatings

    SciTech Connect

    Heller, Daimon K Fahrenholtz, William G. O'Keefe, Matthew J.

    2011-11-15

    Subsurface crevices formed during the deposition of cerium-based conversion coatings were analyzed in cross-section to assess the effect of deposition and post-treatment on the structure and chemistry of phases present. An Al-O containing phase, believed to be amorphous Al(OH){sub 3}, was formed in crevices during coating deposition. Analysis by energy dispersive X-ray spectroscopy revealed the presence of up to 1.6 at.% chlorine within the Al-O phase, which was likely a product of soluble chlorides that were present in the coating solution. Cerium was not detected within crevices. After post-treatment in an 85 deg. C aqueous phosphate solution, the chloride concentration was reduced to {<=} 0.30 at.% and electron diffraction of the Al-O phase produced ring patterns, indicating it had crystallized. Some diffraction patterns could be indexed to gibbsite (Al(OH){sub 3}), but others are believed to be a combination of hydrated aluminum hydroxides and/or oxides. Aluminum phosphate was not identified. Separately from its effect on cerium-based conversion coatings, phosphate post-treatment improved the corrosion resistance of Al 2024-T3 substrates by acting to crystallize Al(OH){sub 3} present on interior surfaces of crevices and by reducing the chloride concentration in this phase. - Highlights: {yields} Analysis of subsurface crevices formed during deposition of Ce-based conversion coatings. {yields} Phosphate post-treatment improved corrosion protection in salt spray testing. {yields} Post-treatment affected the composition and structure of regions within crevices. {yields} Crystallized Al(OH){sub 3} within crevices acted as a more effective barrier to chloride ions.

  17. A comprehensive classification of nucleic acid structural families based on strand direction and base pairing.

    PubMed Central

    Lavery, R; Zakrzewska, K; Sun, J S; Harvey, S C

    1992-01-01

    We propose a classification of DNA structures formed from 1 to 4 strands, based only on relative strand directions, base to strand orientation and base pairing geometries. This classification and its associated notation enable all nucleic acids to be grouped into structural families and bring to light possible structures which have not yet been observed experimentally. It also helps in understanding transitions between families and can assist in the design of multistrand structures. PMID:1383936

  18. Fully-tunable microwave photonic filter with complex coefficients using tunable delay lines based on frequency-time conversions.

    PubMed

    Mokhtari, Arash; Preußler, Stefan; Jamshidi, Kambiz; Akbari, Mahmood; Schneider, Thomas

    2012-09-24

    A fully electrically tunable microwave photonic filter is realized by the implementation of delay lines based on frequency-time conversion. The frequency response and free spectral range (FSR) of the filter can be engineered by a simple electrical tuning of the delay lines. The method has the capability of being integrated on a silicon photonic platform. In the experiment, a 2-tap tunable microwave photonic filter with a 3-dB bandwidth of 2.55 GHz, a FSR of 4.016 GHz, a FSR maximum tuning range from -354 MHz to 354 MHz and a full FSR translation range is achieved. PMID:23037423

  19. Nonstationary amplification of the holographic recording in doped BSO crystals: a base for photorefractive incoherent-to-coherent optical conversion.

    PubMed

    Miteva, M; Dushkina, N; Gospodinov, M

    1995-07-10

    An effect of nonstationary amplification of the holographic recording in pure and transition-metal doped crystals of the sillenite type (Bi(12)SiO(20), or BSO), irradiated in advance with light from the red or near-infrared spectrum, is investigated. This amplification can serve as a base for incoherent-tocoherent optical conversion. It is found that BSO crystals doped with iron and cobalt have a highersensitivity and much wider spatial-frequency range, where the effect of the amplification can be observed,compared with nondoped crystals. PMID:21052232

  20. Graphene-based photovoltaic cells for near-field thermal energy conversion.

    PubMed

    Messina, Riccardo; Ben-Abdallah, Philippe

    2013-01-01

    Thermophotovoltaic devices are energy-conversion systems generating an electric current from the thermal photons radiated by a hot body. While their efficiency is limited in far field by the Schockley-Queisser limit, in near field the heat flux transferred to a photovoltaic cell can be largely enhanced because of the contribution of evanescent photons, in particular for a source supporting a surface mode. Unfortunately, in the infrared where these systems operate, the mismatch between the surface-mode frequency and the semiconductor gap reduces drastically the potential of this technology. In this paper we propose a modified thermophotovoltaic device in which the cell is covered by a graphene sheet. By discussing the transmission coefficient and the spectral properties of the flux, we show that both the cell efficiency and the produced current can be enhanced, paving the way to promising developments for the production of electricity from waste heat. PMID:23474891

  1. Selective Conversion of CO2 to CO with High Efficiency using an Inexpensive Bismuth Based Electrocatalyst

    PubMed Central

    DiMeglio, John L.; Rosenthal, Joel

    2013-01-01

    The wide-scale implementation of solar and other renewable sources of electricity requires improved means for energy storage. An intriguing strategy in this regard is the reduction of CO2 to CO, which generates an energy rich commodity chemical that can be coupled to liquid fuel production. In this work, we report an inexpensive Bismuth Carbon Monoxide Evolving Catalyst (Bi-CMEC) that can be formed upon cathodic polarization of an inert glassy carbon electrode in acidic solutions containing Bi3+ ions. This catalyst can be used in conjunction with ionic liquids to effect the electrocatalytic conversion of CO2 to CO with appreciable current density at overpotentials below 0.2 V. Bi-CMEC is selective for production of CO, operating with a Faradaic efficiency of approximately 95%. When taken together these correspond to a high energy efficiency for CO production, on par with that which has historically only been observed using expensive silver and gold cathodes. PMID:23735115

  2. A scalable multipass laser cavity based on injection by frequency conversion for noncollective Thomson scattering

    SciTech Connect

    Schaeffer, D. B.; Constantin, C. G.; Everson, E. T.; Van Compernolle, B.; Kugland, N. L.; Niemann, C.; Ebbers, C. A.; Glenzer, S. H.

    2010-10-15

    A scalable setup using injection by frequency conversion to establish a multipassing cavity for noncollective Thomson scattering on low density plasmas is presented. The cavity is shown to support >10 passes through the target volume with a 400% increase in energy on target versus a single-pass setup. Rayleigh scattering experiments were performed and demonstrate the viability of the cell to study low density plasmas of the order of 10{sup 12}-10{sup 13} cm{sup -3}. A high-repetition, low-energy, single-pass Thomson scattering setup was also performed on the University of California, Los Angeles Large Plasma Device and shows that the multipass cavity could have a significant advantage over the high-repetition approach due to the cavity setup's inherently higher signal per shot.

  3. A scalable multipass laser cavity based on injection by frequency conversion for noncollective Thomson scattering.

    PubMed

    Schaeffer, D B; Kugland, N L; Constantin, C G; Everson, E T; Van Compernolle, B; Ebbers, C A; Glenzer, S H; Niemann, C

    2010-10-01

    A scalable setup using injection by frequency conversion to establish a multipassing cavity for noncollective Thomson scattering on low density plasmas is presented. The cavity is shown to support >10 passes through the target volume with a 400% increase in energy on target versus a single-pass setup. Rayleigh scattering experiments were performed and demonstrate the viability of the cell to study low density plasmas of the order of 10(12)-10(13) cm(-3). A high-repetition, low-energy, single-pass Thomson scattering setup was also performed on the University of California, Los Angeles Large Plasma Device and shows that the multipass cavity could have a significant advantage over the high-repetition approach due to the cavity setup's inherently higher signal per shot. PMID:21033873

  4. First results with a surface conversion H ion source based on helicon wave mode-driven plasma discharge

    SciTech Connect

    Tarvainen, Ollie A; Geros, Ernest; Rouleau, Gary; Zaugg, Thomas J

    2008-01-01

    The currently employed converter-type negative ion source at Los Alamos Neutron Science Center (LANSCE) is based on cesium enhanced surface production of H{sup -} ion beams in a filament-driven discharge. The extracted H{sup -} beam current is limited by the achievable plasma density, which depends primarily on the electron emission current from the filaments. The emission current can be increased by increasing the filament temperature but, unfortunately, this leads not only to shorter filament lifetime but also to an increase in metal evaporation from the filament, which degrades the performance of the H{sup -} conversion surface. In order to overcome these limitations we have designed and tested a prototype of a surface conversion H{sup -} ion source, based on excitation of helicon plasma wave mode with an external antenna. The source has been operated with and without cesium injection. An H{sup -} beam current of over 12 mA has been transported through the low energy beam transport of the LANSCE ion source test stand. The results of these experiments and the effects of different source parameters on the extracted beam current are presented. The limitations of the source prototype are discussed and future improvements are proposed based on the experimental observations.

  5. Conversion of a metal-organic framework to N-doped porous carbon incorporating Co and CoO nanoparticles: direct oxidation of alcohols to esters.

    PubMed

    Zhou, Yu-Xiao; Chen, Yu-Zhen; Cao, Lina; Lu, Junling; Jiang, Hai-Long

    2015-05-14

    A Co-based metal-organic framework, ZIF-67, has been exploited as a self-template to afford N-doped porous carbon incorporating Co NPs with surface-oxidized CoO species, which exhibit excellent catalytic activity, selectivity and magnetic recyclability toward the direct oxidation of alcohols to esters with O2 as a benign oxidant under mild conditions. PMID:25877956

  6. Energy conversion alternatives study

    NASA Technical Reports Server (NTRS)

    Shure, L. T.

    1979-01-01

    Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

  7. Low Temperature Catalytic Ethanol Conversion Over Ceria-Supported Platinum, Rhodium, and Tin-Based Nanoparticle Systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, Eugene Leo Draine

    Due to the feasibility of ethanol production in the United States, ethanol has become more attractive as a fuel source and a possible energy carrier within the hydrogen economy. Ethanol can be stored easily in liquid form, and can be internally pre-formed prior to usage in low temperature (200°C--400°C) solid acid and polymer electrolyte membrane fuel cells. However, complete electrochemical oxidation of ethanol remains a challenge. Prior research of ethanol reforming at high temperatures (> 400°C) has identified several metallic and oxide-based catalyst systems that improve ethanol conversion, hydrogen production, and catalyst stability. In this study, ceria-supported platinum, rhodium, and tin-based nanoparticle catalyst systems will be developed and analyzed in their performance as low-temperature ethanol reforming catalysts for fuel cell applications. Metallic nanoparticle alloys were synthesized with ceria supports to produce the catalyst systems studied. Gas phase byproducts of catalytic ethanol reforming were analyzed for temperature-dependent trends and chemical reaction kinetic parameters. Results of catalytic data indicate that catalyst composition plays a significant role in low-temperature ethanol conversion. Analysis of byproduct yields demonstrate how ethanol steam reforming over bimetallic catalyst systems (platinum-tin and rhodium-tin) results in higher hydrogen selectivity than was yielded over single-metal catalysts. Additionally, oxidative steam reforming results reveal a correlation between catalyst composition, byproduct yield, and ethanol conversion. By analyzing the role of temperature and reactant composition on byproduct yields from ethanol reforming, this study also proposes how these parameters may contribute to optimal catalytic ethanol reforming.

  8. Demonstration of simultaneous mode conversion and demultiplexing for mode and wavelength division multiplexing systems based on tilted few-mode fiber Bragg gratings.

    PubMed

    Gao, Ya; Sun, Junqiang; Chen, Guodong; Sima, Chaotan

    2015-04-20

    We experimentally demonstrate mode conversion by exploiting optical reflection of tilted few-mode fiber Bragg grating (FM-FBG). Mode conversions from LP(01) mode to higher symmetric and asymmetric modes are achieved, and more than 99.5% conversion efficiency from LP(01) to LP(11) mode is obtained using a 1.6°-tilted FM-FBG. Influences of the weakly tilted FM-FBG parameters on the property of mode conversion is analyzed and discussed. A simultaneous mode conversion and demultiplexing scheme for 4-mode × 3-wavelength multiplexing transmission is proposed and the modal crosstalk is analyzed based on the transmission spectra of the tilted FM-FBGs. The proposed approach shows potential applications in mode and wavelength division multiplexing communication systems. PMID:25969037

  9. A Triple-Band WCDMA Direct Conversion Receiver IC with Reduced Number of Off-Chip Components and Digital Baseband Control Signals

    NASA Astrophysics Data System (ADS)

    Watanabe, Osamu; Ito, Rui; Mitomo, Toshiya; Saigusa, Shigehito; Arai, Tadashi; Toyoda, Takehiko

    This paper presents a triple-band WCDMA direct conversion receiver (DCR) IC that needs a small number of off-chip components and control signals from digital baseband (DBB) IC. The DCR IC consists of 3 quadrature demodulators (QDEMs) with on-chip impedance matching circuit and an analog baseband block (ABB) that contains a low-pass filter (LPF) with fc automatic tuning circuit using no off-chip components and a linear-in-dB variable-gain amplifier (VGA) with on-chip analog high-pass filter (HPF). In order to make use of DBB control-free DC offset canceler, the DCR is designed to avoid large gain change under large interference that causes long transient response. In order to realize that characteristic without increasing quiescent current, the QDEM is used that employs class AB input stage and low-noise common mode feedback (CMFB) output stage. The DCR IC was fabricated in a SiGe BiCMOS process and occupies about 2.9mm×3.0mm. The DCR needs SAW filters only for off-chip components and a gain control signal from DBB IC for AGC loop. The IIP3 of over -4.4dBm for small signal input level and that of over +1.9dBm for large signal input level are achieved. The gain compression of the desired signal is less than 0.3dB for ACS Case-II condition.

  10. A spin-orbit coupling study on the spin inversion processes in the direct methane-to-methanol conversion by FeO+

    NASA Astrophysics Data System (ADS)

    Shiota, Yoshihito; Yoshizawa, Kazunari

    2003-04-01

    Possible spin inversion processes in the direct conversion of methane to methanol by the bare FeO+ complex are discussed by means of spin-orbit coupling (SOC) calculations. This reaction proceeds via two transition states (TSs) in the following way; FeO++CH4→FeO+(CH4)→[TS1]→HO-Fe+-CH3→[TS2]→Fe+(CH3OH)→Fe++CH3OH. B3LYP density functional theory calculations show that the potential energies in the quartet and sextet states lie close and involve three crossing seams that can provide a chance of spin-forbidden transition. The spin-forbidden transition leads to a significant decrease in the barrier heights of TS1 and TS2 that correspond to the hydrogen atom abstraction and the methyl shift, respectively. To evaluate the spin-forbidden transition in the reaction pathway, the SOC matrix elements are calculated along the intrinsic reaction coordinate of the reaction. The SOC analysis along the IRC is useful to look at how the FeO+/CH4 reacting system changes its spin multiplicity between the sextet and quartet surfaces. The strength of the SOC between the low-lying quartet state and the sextet state is 133.6 cm-1 in the reactant complex FeO+(CH4), 21.4 cm-1 in the hydroxo intermediate HO-Fe+-CH3, and 0.3 cm-1 in the product complex Fe+(CH3OH). Since the SOC value decreases along the oxidation process, the ease of spin inversion probability is the first crossing seam, the second crossing seam, and the third crossing seam, in this order.

  11. Novel design of bi-directional triplexer based on PLC

    NASA Astrophysics Data System (ADS)

    Xu, Chenglin; Shen, Linping; Zhou, Dong; Huang, Wei-Ping; Hong, Jin

    2005-09-01

    As the development of the technology, fiber-to-the-home (FTTH) becomes a feasible solution to meet the increasing demand on bandwidth. Due to the massive number of end users, cheap and reliable components become the bottleneck to deploy the new technology. Triplexer is one of the key components in the FTTH and is used by every end user. Currently, the available triplexers are either based on bulk optics or fiber optics with large size and high price due to manual labor involved. Planar lightwave circuit (PLC) is a possible technology for massive production and cost reduction. However, it is very challenging to design such bi-directional triplexer on PLC. The first challenge is that three channels, at λ=1310nm, 1490nm, and 1555nm, are separated unevenly over a very large wavelength range; Secondly, the bandwidths of the three channels, Δλ=100nm, 20nm, and 10nm, are very different. In the paper, we proposed a novel design by combining both coarse WDM and dense WDM. In the design, a multi-mode interference (MMI) device is used for coarse WDM to separate the 1310nm from the other two channels. The dense WDM for the remaining two channels is performed by an array waveguide gratings (AWG). The MMI and AWG are built on the same wafer with monolithic integration. Initial simulation results show it is a very promising device.

  12. Direct detection of martian microorganisms based on fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Kawasaki, Y.

    1999-01-01

    The direct detection of microorganisms and their traces using optical microscopes is one of the most promising techniques to obtain the decisive evidences for extraterrestrial life. The most significant points of this technique are high sensitivity and spatial information with a resolution of 0.2mm. Besides, information on local environments and microscopic ecology can also be obtained. Many difficulties, however, must be solved to get reliable results. We have started to develop a noble technique based on the fluorescence microscopy with special interest to the detection of microorganisms in extreme environments including Mars. The principle is to detect molecules/subcellular organs which are responsible for the three basic characteristics of life; genetic information, metabolism, and discrimination of self from non-self. We have screened fluorescence probes and found several are applicable. We could detect almost all the microorganisms already identified. Discrimination of viable from dead cells was possible. The terrestrial microfossils, some of the artificial primitive microorganism-like-objects, dried bacteria and polycyclic aromatic hydrocarbons mixed with simulated Martian sand could be detected. We are now designing a compact detection hardware.

  13. Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification

    PubMed Central

    Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

    2016-01-01

    Prions are formed of misfolded assemblies (PrPSc) of the variably N-glycosylated cellular prion protein (PrPC). In infected species, prions replicate by seeding the conversion and polymerization of host PrPC. Distinct prion strains can be recognized, exhibiting defined PrPSc biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrPSc assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrPC glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrPC species of interest as substrate. Applying the technique to PrPC glycosylation mutants expressing cells revealed that neither PrPC nor PrPSc glycoform stoichiometry was instrumental to PrPSc formation and strainness perpetuation. Our study supports the view that strain properties, including PrPSc glycotype are enciphered within PrPSc structural backbone, not in the attached glycans. PMID:27384922

  14. Modeling and optimization of photon pair sources based on spontaneous parametric down-conversion

    SciTech Connect

    Kolenderski, Piotr; Banaszek, Konrad; Wasilewski, Wojciech

    2009-07-15

    We address the problem of efficient modeling of photon pairs generated in spontaneous parametric down-conversion and coupled into single-mode fibers. It is shown that when the range of relevant transverse wave vectors is restricted by the pump and fiber modes, the computational complexity can be reduced substantially with the help of the paraxial approximation, while retaining the full spectral characteristics of the source. This approach can serve as a basis for efficient numerical calculations or can be combined with analytically tractable approximations of the phase-matching function. We introduce here a cosine-Gaussian approximation of the phase-matching function that works for a broader range of parameters than the Gaussian model used previously. The developed modeling tools are used to evaluate characteristics of the photon pair sources such as the pair production rate and the spectral purity quantifying frequency correlations. Strategies to generate spectrally uncorrelated photons, necessary in multiphoton interference experiments, are analyzed with respect to trade-offs between parameters of the source.

  15. Robust Fault Detection of Wind Energy Conversion Systems Based on Dynamic Neural Networks

    PubMed Central

    Talebi, Nasser; Sadrnia, Mohammad Ali; Darabi, Ahmad

    2014-01-01

    Occurrence of faults in wind energy conversion systems (WECSs) is inevitable. In order to detect the occurred faults at the appropriate time, avoid heavy economic losses, ensure safe system operation, prevent damage to adjacent relevant systems, and facilitate timely repair of failed components; a fault detection system (FDS) is required. Recurrent neural networks (RNNs) have gained a noticeable position in FDSs and they have been widely used for modeling of complex dynamical systems. One method for designing an FDS is to prepare a dynamic neural model emulating the normal system behavior. By comparing the outputs of the real system and neural model, incidence of the faults can be identified. In this paper, by utilizing a comprehensive dynamic model which contains both mechanical and electrical components of the WECS, an FDS is suggested using dynamic RNNs. The presented FDS detects faults of the generator's angular velocity sensor, pitch angle sensors, and pitch actuators. Robustness of the FDS is achieved by employing an adaptive threshold. Simulation results show that the proposed scheme is capable to detect the faults shortly and it has very low false and missed alarms rate. PMID:24744774

  16. Application of nitrogen sufficiency conversion strategy for microalgae-based ammonium-rich wastewater treatment.

    PubMed

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

    2016-10-01

    Ammonium ([Formula: see text]-N)-rich wastewater, a main cause for eutrophication, can serve as a promising medium for fast microalgae cultivation with efficient [Formula: see text]-N removal. To achieve this goal, a well-controlled three-stage treatment process was developed. Two trophic modes (mixotrophy and heterotrophy) in Stage 1 and Stage 2, with two nitrogen availability conditions (N sufficient and N deprived) in Stage 2, and different [Formula: see text]-N concentrations in Stage 3 were compared to investigate the effects of nitrogen sufficiency conversion on indigenous strain UMN266 for [Formula: see text]-N removal. Results showed that mixotrophic cultures in the first two stages with N deprivation in Stage 2 was the optimum treatment strategy, and higher [Formula: see text]-N concentration in Stage 3 facilitated both microalgal growth and [Formula: see text]-N removal, with average and maximum biomass productivity of 55.3 and 161.0 mg L(-1) d(-1), and corresponding removal rates of 4.2 and 15.0 mg L(-1) d(-1), respectively, superior to previously published results. Observations of intracellular compositions confirmed the optimum treatment strategy, discovering excellent starch accumulating property of strain UMN266 as well. Combination of bioethanol production with the proposed three-stage process using various real wastewater streams at corresponding stages was suggested for future application. PMID:26979571

  17. Integrated, cascading enzyme-/chemocatalytic cellulose conversion using catalysts based on mesoporous silica nanoparticles.

    PubMed

    Lee, Yi-Chun; Dutta, Saikat; Wu, Kevin C-W

    2014-12-01

    This article reports a novel approach to deconstructing cellulose into 5-hydroxymethylfurfural (HMF) with a high yield (46.1%) by integrating a sequential enzyme cascade technique in an aqueous system with solid acid catalysis in an organic-solvent system. We executed the rational design and synthesis of mesoporous silica nanoparticles (MSNs) with various pore sizes and surface functionalities, which proved to be useful for the immobilization of various enzymes (i.e., cellulase and isomerase) and nanoparticles (i.e., magnetic Fe3 O4 ) and for functionalization of various acid groups (i.e., H2 PO3 , COOH, and SO3 H). We separately applied the synthesized biocatalysts (i.e., cellulase-Fe3 O4 @MSN and isomerase-Fe3 O4 @MSN) and chemical catalysts (i.e., HSO3 -MSN) in a sequential cellulose-to-glucose, glucose-to-fructose, and fructose-to-HMF conversion, respectively, across both aqueous- and organic-solvent systems after the optimization of reaction conditions (e.g., reaction temperature, water ratio, catalyst amount). The integrated enzymatic and chemocatalytic concept in this study could be an effective and economically friendly process for various catalytic applications. PMID:25257168

  18. Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification.

    PubMed

    Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

    2016-01-01

    Prions are formed of misfolded assemblies (PrP(Sc)) of the variably N-glycosylated cellular prion protein (PrP(C)). In infected species, prions replicate by seeding the conversion and polymerization of host PrP(C). Distinct prion strains can be recognized, exhibiting defined PrP(Sc) biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrP(Sc) assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrP(C) glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrP(C) species of interest as substrate. Applying the technique to PrP(C) glycosylation mutants expressing cells revealed that neither PrP(C) nor PrP(Sc) glycoform stoichiometry was instrumental to PrP(Sc) formation and strainness perpetuation. Our study supports the view that strain properties, including PrP(Sc) glycotype are enciphered within PrP(Sc) structural backbone, not in the attached glycans. PMID:27384922

  19. Energy conversion based on molecular excited states: Redox splitting in soluble polymers. Final report

    SciTech Connect

    Meyer, T.J.

    1995-12-31

    A general method was developed for preparing complexes of Ru(II) with three different bidentate ligands; it is being extended to monodentate ligands for more synthetic versatility. This method was used to prepare a series of complexes with pre-designed absorption properties, with the goal of ``black absorbers`` for use as antenna chromophores in a light-to-chemical energy conversion array. The energy gap law for nonradiative decay was studied for preparing near-IR luminophores with long excited state lifetimes. The problem of destructive dd excited states in Ru(II) polypyridyl complexes was focused on, with success in preparing an extremely photo-inert complex with monodentate pyridine ligands. Time-resolved resonance Raman and infrared spectroscopy were used to study subtle excited state properties of complexes of Ru(II), Os(II), and Re(I). Success was achieved in controlled immobilization of d{sup 6} chromophores and quenchers on styrenic polymers. Having perfected our synthetic technique, we have begun to optimize the ground and excited state properties such as chromophore density, dipole orientation, and lifetime.

  20. Life-cycle-assessment of fuel-cells-based landfill-gas energy conversion technologies

    NASA Astrophysics Data System (ADS)

    Lunghi, P.; Bove, R.; Desideri, U.

    Landfill-gas (LFG) is produced as result of the biological reaction of municipal solid waste (MSW). This gas contains about 50% of methane, therefore it cannot be released into the atmosphere as it is because of its greenhouse effect consequences. The high percentage of methane encouraged researchers to find solutions to recover the related energy content for electric energy production. The most common technologies used at the present time are internal combustion reciprocating engines and gas turbines. High conversion efficiency guaranteed by fuel cells (FCs) enable to enhance the energy recovery process and to reduce emissions to air, such as NO x and CO. In any case, in order to investigate the environmental advantages associated with the electric energy generation using fuel cells, it is imperative to consider the whole "life cycle" of the system, "from cradle-to-grave". In fact, fuel cells are considered to be zero-emission devices, but, for example, emissions associated with their manufacture or for hydrogen production must be considered in order to evaluate all impacts on the environment. In the present work a molten carbonate fuel cell (MCFC) system for LFG recovery is considered and a life cycle assessment (LCA) is conducted for an evaluation of environmental consequences and to provide a guide for further environmental impact reduction.