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Sample records for catalytic converters suche

  1. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K.

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  2. Acoustics of automotive catalytic converter assemblies

    NASA Astrophysics Data System (ADS)

    Dickey, Nolan S.; Selamet, Ahmet; Parks, Steve J.; Tallio, Kevin V.; Miazgowicz, Keith D.; Radavich, Paul M.

    2003-10-01

    In an automotive exhaust system, the purpose of the catalytic converter is to reduce pollutant emissions. However, catalytic converters also affect the engine and exhaust system breathing characteristics; they increase backpressure, affect exhaust system acoustic characteristics, and contribute to exhaust manifold tuning. Thus, radiated sound models should include catalytic converters since they can affect both the source characteristics and the exhaust system acoustic behavior. A typical catalytic converter assembly employs a ceramic substrate to carry the catalytically active noble metals. The substrate has numerous parallel tubes and is mounted in a housing with swelling mat or wire mesh around its periphery. Seals at the ends of the substrate can be used to help force flow through the substrate and/or protect the mat material. Typically, catalytic converter studies only consider sound propagation in the small capillary tubes of the substrate. Investigations of the acoustic characteristics of entire catalytic converter assemblies (housing, substrate, seals, and mat) do not appear to be available. This work experimentally investigates the acoustic behavior of catalytic converter assemblies and the contributions of the separate components to sound attenuation. Experimental findings are interpreted with respect to available techniques for modeling sound propagation in ceramic substrates.

  3. Catalytic Converters Maintain Air Quality in Mines

    NASA Technical Reports Server (NTRS)

    2014-01-01

    At Langley Research Center, engineers developed a tin-oxide based washcoat to prevent oxygen buildup in carbon dioxide lasers used to detect wind shears. Airflow Catalyst Systems Inc. of Rochester, New York, licensed the technology and then adapted the washcoat for use as a catalytic converter to treat the exhaust from diesel mining equipment.

  4. Durability of ceramic catalytic converters for motorcycles

    SciTech Connect

    Reddy, K.P.; Scott, P.L.; Hwang, H.S.; Mooney, J.J.

    1995-12-31

    Motorcycle exhaust emission standards throughout the world are becoming more stringent. Emission control systems utilizing the catalytic converter are already in production in Taiwan for 2-stroke engine motorcycles. Catalysts designed for 2-stroke engines encounter a more severe exhaust environment than do those designed for 4-stroke engines. The two aspects of increased severity are the higher temperatures and higher stresses due to engine vibrations. Precious metal catalysts have been designed to operate in the thermal environment of 2-stroke engines and such catalysts have been successfully applied to both metal and ceramic substrates. However, until now, only the metal substrate catalysts have been utilized in motorcycle application. Ceramic based catalysts have not been considered because the mounting material that holds the catalyst substrate in place did not have enough durability to withstand the thermal/vibrational forces encountered in 2-stroke engine exhaust. Ceramic substrates have many advantages such as superior high temperature strength, which is especially important for the 2-stroke engine application, flexibility in cell shape and density, and lower cost. To realize these benefits, efforts were made in this study to develop better mounting systems. The results of this effort indicate that the durability requirements of 2-stroke engine can be met with the ceramic catalyst substrates if the improved mounting designs reported in the present study are employed.

  5. Catalytic converter for a diesel engine

    SciTech Connect

    Cornelison, R.C.; Retallick, W.B.

    1987-06-16

    A catalytic converter for a diesel engine is describes comprising at least one metal strip, the strip being formed into an undulating series of U-bends, the series comprising U-bends that are open on top and U-bends that are closed on top, the open and closed U-bends alternating in a checkerboard pattern, the strip being aligned generally transversely to the direction of flow of exhaust gas from the engine, the strip defining a tortuous flow path for exhaust gas from the engine, the strip being coated with a combination catalyst.

  6. On a Novel Diffuser for Efficient Automotive Catalytic Converters

    NASA Astrophysics Data System (ADS)

    Hirata, Katsuya; Ota, Mitsuhiko; Oda, Ryoji; Tanigawa, Hirochika; Funaki, Jiro

    In automobile-exhaust systems, catalytic converters are main components and produce substantial pressure drops, which induce engine-power loss and fuel-consumption rise. On the other hand, catalytic converters are required for the uniformity of flow through a catalytic substrate, which causes uniformity of thermal distribution and high catalytic-conversion efficiency. The purpose of this study is to reduce the pressure losses and to improve the flow distribution simultaneously, under spatial constraints. The authors propose a new type of device and show its performance experimentally. Namely, the authors place a dome as a flow deflector inside the diffuser in front of a catalyst in order to suppress flow separation. The converter tested in the present study has a standard cylindrical ceramic substrate with a circular cross section. As a result, we present the optimum dome geometry that can reduce the pressure loss by 22% as compared to a no-dome converter.

  7. Retrofit catalytic converter for wood-burning stoves

    SciTech Connect

    1983-01-01

    The major purpose of this project was to design, fabricate, test, and evaluate a retrofit catalytic converter for woodburning stoves. In the interim between our date of application March 5, 1981 and the beginning of the grant period December 1, 1981, several such devices became commercially available. Therefore, we decided to modify the purpose and direction of our project. In summary, we designed and constructed a calorimeter room in a building located on the campus of Northern Kentucky University. We equipped this room with a woodburning stove and a metal chimney extending through the roof. We designed and constructed the appropriate instrumentation for monitoring the heat output of the stove. We observed and recorded the operating characteristics of this stove over a period of several days. We then equipped the stove with a barometric damper and repeated the experiment. We are now in the process of equipping the stove with a catalytic converter. Thus the major emphasis of the project currently is to test and evaluate several commercial retrofit devices which are purported to reduce creosote and/or increase the efficiency of a woodburning stove.

  8. Preparation and Use of a Room-Temperature Catalytic Converter

    NASA Astrophysics Data System (ADS)

    Wong, Gareth; Mark, Bernard; Chen, Xijia; Furch, Toran; Singmaster, K. A.; Wagenknecht, Paul S.

    2001-12-01

    A solid-state catalyst that effectively converts a CO/air mixture to CO2 at room temperature is readily prepared. The catalyst, which is composed of metallic gold on iron(III) oxide, is loaded into a simple flow cell to test its catalytic activity. Mixtures of CO and air are run through the catalyst and subsequently analyzed by gas-phase infrared spectroscopy to determine the effectiveness of the catalyst.

  9. Converting sugars to sugar alcohols by aqueous phase catalytic hydrogenation

    DOEpatents

    Elliott, Douglas C.; Werpy, Todd A.; Wang, Yong; Frye, Jr., John G.

    2003-05-27

    The present invention provides a method of converting sugars to their corresponding sugar alcohols by catalytic hydrogenation in the aqueous phase. It has been found that surprisingly superior results can be obtained by utilizing a relatively low temperature (less than 120.degree. C.), selected hydrogenation conditions, and a hydrothermally stable catalyst. These results include excellent sugar conversion to the desired sugar alcohol, in combination with long life under hydrothermal conditions.

  10. Thermal reliability and performance improvement of close-coupled catalytic converter

    SciTech Connect

    Hijikata, Toshihiko; Kurachi, Hiroshi; Katsube, Fumio; Honacker, H. van

    1996-09-01

    This paper proposes a high temperature catalytic converter design using a ceramic substrate and intumescent matting. It also describes the improvement of converter performance using an advanced thin wall ceramic substrate. Due to future tightening of emission regulations and improvement of fuel economy, higher exhaust gas temperatures are suggested. Therefore, reduction of thermal reliability of an intumescent mat will be a concern because the catalytic converter will be exposed to high temperatures. For this reason, a new design converter has been developed using a dual cone structure for both the inlet and outlet cones. This minimizes heat conduction through the cone and decreases the temperature affecting the mat area. This design converter, without the use of a heat-shield, reduces the converter surface temperature to 441 C despite a catalyst bed temperature of 1,050 C. The long term durability of the converter is demonstrated by the hot vibration test. Since the new design converter does not need a heat-shield, the catalyst diameter can be enlarged by the width of the air gap used in the current design converter. By using an advanced thin wall ceramic substrate, such as 0.11 mm/620 kcpsm (4 mil/400 cpsi), it is possible to improve emission performance and pressure drop compared with the conventional 0.16 mm/620 kcpsm (6 mil/400 cpsi) ceramic substrate.

  11. Reducing cold-start emissions by catalytic converter thermal management

    SciTech Connect

    Burch, S D; Potter, T F; Keyser, M A; Brady, M J; Michaels, K F

    1995-01-01

    Vacuum insulation and phase-change thermal storage have been used to enhance the heat retention of a prototype catalytic converter. Storing heat in the converter between trips allows exhaust gases to be converted more quickly, significantly reducing cold-start emissions. Using a small metal hydride, the thermal conductance of the vacuum insulation can be varied continuously between 0.49 and 27 W/m{sup 2}K (R-12 to R-0.2 insulation) to prevent overheating of the catalyst. A prototype was installed in a Dodge Neon with a 2.0-liter engine. Following a standard preconditioning and a 23-hour cold soak, an FTP (Federal Test Procedure) emissions test was performed. Although exhaust temperatures during the preconditioning were not hot enough to melt the phase-change material, the vacuum insulation performed well, resulting in a converter temperature of 146{degrees}C after the 23-hour cold soak at 27{degrees}C. Compared to the same converter at ambient conditions, overall emissions of CO and HC were reduced by 52 % and 29 %, to 0.27 and 0.037 g/mile, respectively. The maximum converter temperature during the FTP cycle was 720{degrees}C. This limited testing was performed with a nearly-fresh palladium-only catalyst, but demonstrates the potential of this vacuum insulation approach for emissions reduction and thermal control. Further testing is ongoing. An initial assessment of several production issues is made, including high-volume fabrication challenges, durability, and cost.

  12. Performance simulations of catalytic converters during the Federal Test Procedure

    SciTech Connect

    Shen, H.; Shamim, T.; Sengupta, S.; Son, S.; Adamczyk, A.A.

    1999-07-01

    A numerical study is carried out to predict the tailpipe emissions and emission conversion efficiencies of unburned hydrocarbon, nitrogen oxide and carbon monoxide flowing through a catalytic converter during the Federal Test Procedure (FTP). The model considers the effect of heat transfer in the catalytic converter, coupled with catalyst chemical kinetics, including an oxygen storage mechanism. The resulting governing equations based on the conservation of mass and energy are solved by a tridiagonal matrix algorithm (TDMA) with a successive line under relaxation method. The numerical scheme for this non-linear problem is found to have good convergence efficiency. The simulation for the complete FTP cycle is accomplished in less than fifteen minutes on a desktop personal computer. A 13-step reaction mechanism plus a nine-step O{sub 2} storage mechanism is used to simulate the chemical kinetics. The energy equations include the heat loss due to conduction and convection plus the energy liberated by chemical reactions. The effect of radiation is assumed to be negligible and is not considered. The results of the numerical model for both the instantaneous and accumulated emissions are found to be in good agreement with experimental measurements. The conversion efficiencies of HC, CO and NO as predicted by the model are found to be within 5% of those dynamic measurements, and calculated results of accumulated HC, CO and NO{sub x} are in fair agreement with experimental measurements. The transient measurements are also used to check the robustness of the numerical model. The model is found to be robust and hence can simulate various operating conditions of engine output to the converter.

  13. TEC as electric generator in an automobile catalytic converter

    SciTech Connect

    Svensson, R.; Holmlid, L.

    1996-12-31

    Modern cars use more and more electric power due to more on-board electric systems, e.g., ABS brakes, active suspension systems, electric windows, chair adjustment systems and electronic engine control systems. One possible energy source for electricity generation is to use the waste heat from the car`s engine, which generally is as much as 80% of the total energy from the combustion of the gasoline. Maybe the best location to tap the excess heat is the Catalytic Converter (Cat) in the exhaust system or perhaps at the exhaust pipes close to the engine. The Cat must be kept within a certain temperature interval. Large amounts of heat are dissipated through the wall of the Cat. A Thermionic Energy Converter (TEC) in coaxial form could conveniently be located around the ceramic cartridge of the Cat. Since the TEC is a rather good heat insulator before it reaches its working temperature the Cat will reach working temperature faster, and the final temperature of it can be controlled better when encapsulated in a concentric TEC arrangement. It is also possible to regulate the temperature of the Cat and the TEC by controlling the electrical load of the TEC. The possible working temperatures of present and future Cats appear very suitable for the new low work function collector TEC, which has been demonstrated to work down to 470 K.

  14. A theory for fast-igniting catalytic converters

    SciTech Connect

    Leighton, D.T.; Chang, H.C.

    1995-08-01

    Using asymptotic expansion and numerical analysis, the authors demonstrate how the step-response ignition time of an automobile catalytic converter depends on the ratio of the reaction rate to the interphase heat-transfer rate, as measured by a key Damkoehler parameter X and the degree of monolith subcooling n. In the region of low reaction rate at small X, the normalized ignition time t scaled by the homogeneous ignition time t{sup {infinity}} from the inlet gas temperature is (t/t{sup {infinity}}) = 1 + 2X{sup 1/2}{vert_bar}ln(X{sup 1/2}/2n){vert_bar}{sup 1/2}, and the ignition takes place at a thermal front deep in the monolith. At large X when the reaction rate is high, ignition occurs at the leading edge of the monolith with (t/t{sup {infinity}}) = 2.50 + X(ln n {minus} 0.34). The delay in ignition time with increasing X is due to a Taylor-Aris dispersion mechanism induced by interphase heat transfer. Although the small-X ignition mechanism is faster, its downstream ignition location leads to a very slow upstream propagation of the thermal front that follows ignition. An optimal converter system that ignites in 13 s, 25% of the current value in a standard step-response test, is then designed by placing a small igniter, which ignites by the small-X mechanism, upstream to preheat the current converter which then ignites by the large-X mechanism. The length of the igniter is kept small by bypassing 2/3 of the exhaust since, from the authors` theory, t{sup {infinity}} is independent of the gas velocity.

  15. Potential for recovery of cerium contained in automotive catalytic converters

    USGS Publications Warehouse

    Bleiwas, Donald I.

    2013-01-01

    Catalytic converters (CATCONs) are required by Federal law to be installed in nearly all gasoline- and diesel-fueled onroad vehicles used in the United States. About 85 percent of the light-duty vehicles and trucks manufactured worldwide are equipped with CATCONs. Portions of the CATCONs (called monoliths) are recycled for their platinum-group metal (PGM) content and for the value of the stainless steel they contain. The cerium contained in the monoliths, however, is disposed of along with the slag produced from the recycling process. Although there is some smelter capacity in the United States to treat the monoliths in order to recover the PGMs, a great percentage of monoliths is exported to Europe and South Africa for recycling, and a lesser amount is exported to Japan. There is presently no commercial-scale capacity in place domestically to recover cerium from the monoliths. Recycling of cerium or cerium compounds from the monoliths could help ensure against possible global supply shortages by increasing the amount that is available in the supply chain as well as the number and geographic distribution of the suppliers. It could also reduce the amount of material that goes into landfills. Also, the additional supply could lower the price of the commodity. This report analyzes how much cerium oxide is contained in CATCONs and how much could be recovered from used CATCONs.

  16. Bioaccessibility of platinum group elements in automotive catalytic converter particulates.

    PubMed

    Turner, Andrew; Price, Simon

    2008-12-15

    The bioaccessibilities of the platinum group elements (PGE): Rh, Pd, and Pt; and the catalyzator poison, Pb, have been determined in particles derived from milled automotive catalytic converters using a physiologically based extraction test (PBET) that simulates, sequentially, the chemical conditions encountered in the human stomach and intestine. PGE accessibility, relative to total metal concentration, was generally less than a few percent, but increased in the stomach with decreasing pH (from 4 to 1) and/or increasing chloride concentration, and with decreasing particle concentration. In most cases, bioaccessibility increased from the acidic stomach to the neutral, carbonate-rich intestine. Bioaccessibility of Pb displayed similar pH and particle concentration dependencies to PGE in the stomach, but this metal exhibited significantly greater mobilization (up to 80%) overall and a reduction in accessibility from the stomach to intestine. Reaction kinetics of PGE dissolution in the stomach at pH 2.5 were modeled using a combined surface reaction-diffusion controlled mechanism with rate constants of 0.068, 0.031, and 0.015 (microg L(-1))(-1) h(-1) for Rh, Pd, and Pt, respectively. For Pb, however, mobilization proceeded via a different mechanism whose time-dependence was fitted with an empirical, logarithmic equation. Overall, PGE bioaccessibility appeared to be controlled by dissolution rates of metallic nanoparticles in the stomach, and solubility and kinetic constraints on inorganic species (chlorides, hydroxychlorides, and carbanatochlorides) and undefined organic complexes formed in the simulated gastrointestinal tract. Further studies are required to elucidate any effects engendered by the long-term oral exposure of small quantities of these species. PMID:19174929

  17. Catalytic converter applications for two stroke, spark-ignited marine engines

    SciTech Connect

    Fujimoto, Hiroaki; Isogawa, Atsushi; Matsumoto, Naoto

    1995-12-31

    When catalytic converters are used for cleansing of exhaust gas from two-stroke marine engines, new issues must be brought up in combination with prior technology. Therefore, a study was made of V6, 2600cc engine having a large volume of hydrocarbon emissions with respect to three issues: (1) To what degree seawater effects catalytic converter performance and possible countermeasures; (2) Effects attained on cleansing level and catalyst temperature; (3) Finding abatement levels for catalyst deterioration and exhaust emission output in the marine mode. It was found that physical adsorption was a significant factor in catalytic degradation resulting from direct contact with seawater. The cleansing levels obtained when a marine engine is equipped with a catalyst converter were found by clarifying the extent of effects of catalyst volume, performance and temperature. The reduction obtained in exhaust emission allowing for a deterioration factor, is shown in a catalytic converter heated to the maximum temperature of 960 C.

  18. Biologic effects of auto emissions. I. Exhaust from engine with and without catalytic converter.

    PubMed

    Lee, S D; Malanchuk, M; Finelli, V N

    1976-05-01

    This paper relates to the efficacy of a catalytic converter in reducing the levels of certain pollutants emitted from an automobile engine and to the reduction and/or elimination of gross biologic damages in animals exposed to emissions from an exhaust system containing such catalysts. Groups of rats were exposed to diluted emissions from an automobile engine with and without catalyst. Concomitantly, a comparative experiment was conducted by exposing a group of rats to carbon monoxide alone (575 mg/m3). The parameters measured included hematocrit, serum LDH, GOT, and lysozyme. An elevation in hematocrit was observed in animals of the experiment run without catalyst and in those exposed to carbon monoxide; the use of the catalyst reduced the carbon monoxide levels in the exposure chambers by more than tenfold and prevented these bioeffects from occurring. Serum LDH activity was elevated in the groups of rats in the experiment conducted without catalyst, but no alternation was observed in the animals from the experiment utilizing the catalyst or in those exposed to carbon monoxide alone. The data obtained in this study showed that acute exposure to noncatalytic emissions caused significant alterations in certain biologic parameters. Conversely, the introduction of an oxidizing catalytic converter into the engine exhaust system reduced or prevented such biologic damage. PMID:58066

  19. Demonstration of a Catalytic Converter Using a Lawn Mower Engine

    ERIC Educational Resources Information Center

    Young, Mark A.

    2010-01-01

    Catalytic conversion is an important tool in environmental-remediation strategies and source removal of pollutants. Because a catalyst is regenerated, the chemistry can be extremely effective for conversion of undesirable pollutant species to less harmful products in situations where the pollutants have accumulated or are being continuously…

  20. Pre-converted nitric oxide gas in catalytic reduction system

    DOEpatents

    Hsiao, Mark C.; Merritt, Bernard T.; Penetrante, Bernardino M.; Vogtlin, George E.

    1999-01-01

    A two-stage catalyst comprises an oxidative first stage and a reductive second stage. The first stage is intended to convert NO to NO.sub.2 in the presence of O.sub.2. The second stage serves to convert NO.sub.2 to environmentally benign gases that include N2, CO2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber. An oxidizing first catalyst converts NO to NO.sub.2 in the presence of O.sub.2 and includes platinum/alumina, e.g., Pt/Al.sub.2 O.sub.3 catalyst. A flow of hydrocarbons (C.sub.x H.sub.y) is input from a pipe into a second chamber. For example, propene can be used as a source of hydrocarbons. The NO.sub.2 from the first catalyst mixes with the hydrocarbons in the second chamber. The mixture proceeds to a second reduction catalyst that converts NO.sub.2 to N2, CO2, and H.sub.2 O, and includes a gamma-alumina .gamma.-Al.sub.2 O.sub.3. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the second catalyst.

  1. Pre-converted nitric oxide gas in catalytic reduction system

    DOEpatents

    Hsiao, M.C.; Merritt, B.T.; Penetrante, B.M.; Vogtlin, G.E.

    1999-04-06

    A two-stage catalyst comprises an oxidative first stage and a reductive second stage. The first stage is intended to convert NO to NO{sub 2} in the presence of O{sub 2}. The second stage serves to convert NO{sub 2} to environmentally benign gases that include N{sub 2}, CO{sub 2}, and H{sub 2}O. By preconverting NO to NO{sub 2} in the first stage, the efficiency of the second stage for NO{sub x} reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber. An oxidizing first catalyst converts NO to NO{sub 2} in the presence of O{sub 2} and includes platinum/alumina, e.g., Pt/Al{sub 2}O{sub 3} catalyst. A flow of hydrocarbons (C{sub x}H{sub y}) is input from a pipe into a second chamber. For example, propene can be used as a source of hydrocarbons. The NO{sub 2} from the first catalyst mixes with the hydrocarbons in the second chamber. The mixture proceeds to a second reduction catalyst that converts NO{sub 2} to N{sub 2}, CO{sub 2}, and H{sub 2}O, and includes a {gamma}-Al{sub 2}O{sub 3}. The hydrocarbons and NO{sub x} are simultaneously reduced while passing through the second catalyst. 9 figs.

  2. Novel techniques for the synthesis of three-way catalytic converter support materials

    NASA Astrophysics Data System (ADS)

    Anyaba, Prince Nwabueze

    Current automobiles use catalytic converters, consisting of noble metals on an oxide support, to convert noxious engine exhaust pollutants into less harmful species. The development of mesoporous oxide supports with optimal pore geometries could enable these devises to decrease in size and weight and significantly reduce the metal loadings required to achieve optimal performance. Thus, in this work, I investigated a wide range of techniques for the synthesis of mesoporous oxides to determine if they could be adapted to ceria-zirconia-yttria mixed oxide (CZY) systems, which are the industry standard for the optimal oxide support for catalytic converter applications. Additionally, I compared and critically evaluated the catalytic performance of the CZY mixed oxides, which were synthesized from the various templating techniques. The catalytic performance test was broken up into two: catalyst activity test which was determined based on the light-off temperatures at which 50% conversion of the reacting species have been converted; and resistance to surface area loss under accelerated aging at heating rate of 20°C/min form 700 to 1000°C, with the final temperature being held fixed for 4 h. To date, the most cost effective methods for preparing mesoporous materials are via techniques that employ templates or structure directing agents. These templates can be divided into two groups: endo-templates (i.e., soft templates, such as surfactants, dendrimers, and block copolymers) and exo-templates (i.e., hard templates, such as porous carbons and resins). The soft templating techniques generally involve both sol-gel and templating methods, while the hard templates required no sol-gel chemistry to achieve the desired templating effect. The precursors for ceria, zirconia, and yttria used were cerium (III) nitrate hexahydrate, zirconyl nitrate, and yttrium nitrate hexahydrate, respectively. The mesoporous CZY materials that were synthesized had surface area values that were

  3. MTBE, methane, ethylene and regulated exhaust emissions from vehicles with deactivated catalytic converters

    NASA Astrophysics Data System (ADS)

    Poulopoulos, S. G.; Philippopoulos, C. J.

    In the present work, the effect of the gradual deactivation of a three-way catalytic converter on the exhaust emissions was studied. The exhaust gases were analyzed for CO, HC (i.e. total unburned organic compounds), MTBE, methane and ethylene, before and after their catalytic treatment, in a wide range of engine operating conditions. The thermal aging of the catalytic converter resulted in an increase in the required time for the start of its operation and loss of its auto thermal operation. The catalytic efficiency was significantly decreased after each thermal aging step, especially at idle conditions. As a result, CO and especially HC emissions were increased, whereas ethylene and MTBE emissions were multiplied by a factor of 6-7 at 3.81 hp, in the case of the deactivated catalyst.

  4. Time domain computational modeling of viscothermal acoustic propagation in catalytic converter substrates with porous walls

    NASA Astrophysics Data System (ADS)

    Dickey, N. S.; Selamet, A.; Miazgowicz, K. D.; Tallio, K. V.; Parks, S. J.

    2005-08-01

    Models for viscothermal effects in catalytic converter substrates are developed for time domain computational methods. The models are suitable for use in one-dimensional approaches for the prediction of exhaust system performance (engine tuning characteristics) and radiated sound levels. Starting with the ``low reduced frequency'' equations for viscothermal acoustic propagation in capillary tubes, time domain submodels are developed for the frequency-dependent wall friction, frequency-dependent wall heat transfer, and porous wall effects exhibited by catalytic converter substrates. Results from a time domain computational approach employing these submodels are compared to available analytical solutions for the low reduced frequency equations. The computational results are shown to agree well with the analytical solutions for capillary geometries representative of automotive catalytic converter substrates.

  5. The investigation of emission characteristics and carbon deposition over motorcycle monolith catalytic converter using different fuels

    NASA Astrophysics Data System (ADS)

    Jia, Li-Wei; Zhou, Wen-Long; Shen, Mei-Qing; Wang, Jun; Lin, Man-Qun

    The effects of MTBE-blended gasoline and 10% (v/v) ethanol-gasoline blended fuel (E10) on HC, CO and NO x conversions over catalytic converters were investigated. Two 4-stroke motorcycle engines outfitted with typical three-way catalytic converters were used and regulated emissions were measured according to ECE-40 test cycle. The results show that the influence of E10 on the catalytic conversion is less significant at grinding stages, compared with that of MTBE-blended gasoline, the catalytic conversion, however, decreases remarkably for E10 at the point of 10 000 km. The carbon deposition information in the direction of the radius of two used monolith exhaust catalytic converters was studied by SEM, EPMA, XPS, TG-DTA and FTIR after a 10 000 km test program. The results indicate that carbon deposition occurs first at the center of a converter, gradually extending to its edge. The carbonaceous species are in the form of C xH y if the vehicle is fueled with MTBE-blended gasoline, whereas the carbonaceous species are C xH yO for E10. The majority of the carbonaceous species are deposited on the precious metal (PM) sites. Further, aromatic rings, alkyl groups and their partial oxidation products are found in the carbonaceous deposit.

  6. Study on the thermal deactivation of motorcycle catalytic converters by laboratory aging tests.

    PubMed

    Chen, Yi-Chi; Chen, Lu-Yen; Yu, Yi-Hsien; Jeng, Fu-Tien

    2010-03-01

    Catalytic converters are used to curb exhaust pollution from motorcycles in Taiwan. A number of factors, including the length of time the converter is used for and driving conditions, affect the catalysts' properties during periods of use. The goal of this study is to resolve the thermal deactivation mechanism of motorcycle catalytic converters. Fresh catalysts were treated under different aging conditions by laboratory-scale aging tests to simulate the operation conditions of motorcycle catalytic converters. The aged catalysts were characterized by analytical techniques in order to provide information for investigating deactivation phenomena. The time-dependent data of specific surface areas were subsequently used to construct kinetics of sintering at the specific temperature. According to the analytical results of the catalysts' properties, the increase in aging temperature causes an increase in pore size of the catalysts and a decrease in the specific surface area. The aged catalysts all exhibited lower performances than the fresh ones. The reduction in catalytic activity is consistent with the reduction in the loss of specific surface area. The finding of catalytic properties' dependence on temperature is consistent with the thermally activated theory. In contrast, the effect of the aging time on the specific surface area was only significant during the initial few hours. The high correlation between specific surface areas measured by the Brunauer-Emmett-Teller (BET) method and predicted by the constructed model verifies that the prediction models can predict the sintering rate reasonably under the aging conditions discussed in this study. As compared to automobile catalytic converters, the differences of structures and aging conditions are made less obvious by the deactivation phenomena of motorcycles. PMID:20426275

  7. QM/MM investigation of the catalytic mechanism of angiotensin-converting enzyme.

    PubMed

    Mu, Xia; Zhang, Chunchun; Xu, Dingguo

    2016-06-01

    Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II and degrades bradykinin and other vasoactive peptides. ACE inhibitors are used to treat diseases such as hypertension and heart failure. It is thus highly desirable to understand the catalytic mechanism of ACE, as this should facilitate the design of more powerful and selective ACE inhibitors. ACE exhibits two different active domains, the C-domain and the N-domain. In this work, we systematically investigated the inhibitor- and substrate-binding patterns in the N-domain of human ACE using a combined quantum mechanical and molecular mechanical approach. The hydrolysis of hippuryl-histidyl-leucine (HHL) as catalyzed by the N-domain of human somatic ACE was explored, and the effects of chloride ion on the overall reaction were also investigated. Two models, one with and one without a chloride ion at the first binding position, were then designed to examine the chloride dependence of inhibitor-substrate binding and the catalytic mechanism. Our calculations indicate that the hydrolysis reaction follows a stepwise general base/general acid catalysis path. The estimated mean free energy barrier height in the two models is about 15.6 kcal/mol, which agrees very well with the experimentally estimated value of 15.8 kcal/mol. Our simulations thus suggest that the N-domain is in a mixed form during ACE-catalyzed hydrolysis, with the single-chloride-ion and the double-chloride-ion forms existing simultaneously. Graphical Abstract Superposition of ACE C- and N- domains. PMID:27184002

  8. Study and manufacture of a para-/ortho-hydrogen catalytic converter for a space cryostat

    NASA Astrophysics Data System (ADS)

    Baston, A. H.; Bradshaw, T. W.; Butler, G.; Clark, N. S.; Chadwick, A. T.; Harris, D. H. C.; Leach, F.; Norris, J. O. W.; Price, D.

    1986-01-01

    The design and optimization of a para-/ortho-hydrogen converter to increase the efficiency and lifetime of the hydrogen cryogenic system of the ISO project are described. Catalyst technology and associated heat transfer technology is evaluated. Four catalyst systems were characterized. Their catalytic activity under the orbital conditions anticipated for the three radiation shields of ISO are reported. Results from experiments on in situ deactivation and reactivation are given, indicating that this is a key parameter. Iron oxide gel is the most promising catalyst system. A full scale prototype converter was designed to ESTEC specifications, and three converters were manufactured and tested. Performance, except for two small details, meets or exceeds specification. Plans for the development and testing of flight unit converters are proposed.

  9. Development of a para-orthohydrogen catalytic converter for a solid hydrogen cooler

    NASA Technical Reports Server (NTRS)

    Nast, T. C.; Hsu, I. C.

    1984-01-01

    Design features of a tested catalytic converter for altering vented cryogenic parahydrogen used as a coolant on spacecraft into a para-ortho equilibrium for channeling to other cooling functions are described. The hydrogen is expected to be stored in either liquid or solid form. A high surface area Ni-on-Si catalyst was selected for tests at an operating pressure of 2 torr at a ratio of 1000 gr catalyst for a gr/sec hydrogen flow. Cylindrical and radial flow geometries were tried and measurements centered on the converter efficiencies at different operating temperatures when the converter was placed in the vent line of the H2 cooler. Efficiencies ranging from 10-100 percent were obtained for varying flow rates. Further testing is necessary to characterize the converter performance under a wider range of operating temperatures and environments.

  10. Emission reduction from a diesel engine fueled by pine oil biofuel using SCR and catalytic converter

    NASA Astrophysics Data System (ADS)

    Vallinayagam, R.; Vedharaj, S.; Yang, W. M.; Saravanan, C. G.; Lee, P. S.; Chua, K. J. E.; Chou, S. K.

    2013-12-01

    In this work, we propose pine oil biofuel, a renewable fuel obtained from the resins of pine tree, as a potential substitute fuel for a diesel engine. Pine oil is endowed with enhanced physical and thermal properties such as lower viscosity and boiling point, which enhances the atomization and fuel/air mixing process. However, the lower cetane number of the pine oil hinders its direct use in diesel engine and hence, it is blended in suitable proportions with diesel so that the ignition assistance could be provided by higher cetane diesel. Since lower cetane fuels are prone to more NOX formation, SCR (selective catalyst reduction), using urea as reducing agent, along with a CC (catalytic converter) has been implemented in the exhaust pipe. From the experimental study, the BTE (brake thermal efficiency) was observed to be increased as the composition of pine oil increases in the blend, with B50 (50% pine oil and 50% diesel) showing 7.5% increase over diesel at full load condition. The major emissions such as smoke, CO, HC and NOX were reduced by 70.1%, 67.5%, 58.6% and 15.2%, respectively, than diesel. Further, the average emissions of B50 with SCR and CC assembly were observed to be reduced, signifying the positive impact of pine oil biofuel on atmospheric environment. In the combustion characteristics front, peak heat release rate and maximum in-cylinder pressure were observed to be higher with longer ignition delay.

  11. Impact of Hong Kong's Voluntary Catalytic Converter Replacement Programme on Roadside Air Quality

    NASA Astrophysics Data System (ADS)

    Simpson, I. J.; Guo, H.; Louie, P. K. K.; Luk, C.; Lyu, X.; Meinardi, S.; Yam, Y. S.; Blake, D. R.

    2015-12-01

    As part of its ongoing policies to improve roadside air quality, in 2013 the Hong Kong government launched an incentive programme to replace catalytic converters and oxygen sensors in taxis and light buses mainly fueled by liquefied petroleum gas (LPG). The majority of replacements occurred from October 2013 to April 2014, with 75% of eligible vehicles participating in the programme, or 16,472 vehicles. Based on taxi exhaust measurements at a Hong Kong vehicle testing facility, the concentrations of n-butane, propane and i-butane (the primary components of LPG) decreased by 97% following the replacements. To determine the impact of the programme on roadside air quality, long-term measurements of volatile organic compounds (VOCs) were analyzed before, during and after the replacement programme, mainly at a busy roadside location in Mong Kok, Hong Kong. A clear decrease in the levels of major pollutants associated with LPG vehicle exhaust was observed at the roadside. For example, average (± 1 standard deviation) n-butane levels from October to April decreased from 13.0 ± 3.6 and 13.9 ± 2.6 ppbv in the two years preceding the programme, to 9.2 ± 2.9 ppbv during the programme, to 6.2 ± 1.7 ppbv the year after the programme. By contrast, compounds such as i-pentane that are not strongly associated with LPG or with LPG exhaust remained steady, averaging 0.90 ± 0.34, 1.01 ± 0.31, 0.93 ± 0.37, and 0.91 ± 0.42 ppbv from October to April of 2011/12, 2012/13, 2013/14 and 2014/15, respectively. Impacts of the programme on roadside levels of nitrogen oxides (NOx) and ozone (O3) will also be discussed. Because many taxis are high mileage vehicles that travel several hundred kilometers daily, their catalytic converters need to be replaced approximately every 18 months. Therefore ongoing vehicle maintenance will be required in order to preserve the gains made from this initial subsidy programme.

  12. Effects of a catalytic converter on PCDD/F, chlorophenol and PAH emissions in residential wood combustion.

    PubMed

    Kaivosoja, T; Virén, A; Tissari, J; Ruuskanen, J; Tarhanen, J; Sippula, O; Jokiniemi, J

    2012-07-01

    Catalytic converters can be used to decrease carbon monoxide, organic compounds and soot from small-scale wood-fired appliances. The reduction is based on the oxidation of gaseous and particulate pollutants promoted by catalytic transition metal surfaces. However, many transition metals have also strong catalytic effect on PCDD/F formation. In this study birch logs were burned in a wood-fired stove (18 kW) with and without a catalytic converter with palladium and platinum as catalysts. PCDD/F, chlorophenol and PAH concentrations were analyzed from three phases of combustion (ignition, pyrolysis and burnout) and from the whole combustion cycle. PCDD/F emissions without the catalytic converter were at a level previously measured for wood combustion (0.15-0.74 ng N m(-3)). PAH emissions without the catalytic converter were high (47-85 mg N m(-3)) which is typical for batch combustion of wood logs. Total PAH concentrations were lower (on average 0.8-fold), and chlorophenol and PCDD/F levels were substantially higher (4.3-fold and 8.7-fold, respectively) when the catalytic converter was used. Increase in the chlorophenol and PCDD/F concentrations was most likely due to the catalytic effect of the platinum and palladium. Platinum and palladium may catalyze chlorination of PCDD/Fs via the Deacon reaction or an oxidation process. The influence of emissions from wood combustion to human health and the environment is a sum of effects caused by different compounds formed in the combustion. Therefore, the usage of platinum and palladium based catalytic converters to reduce emissions from residential wood combustion should be critically evaluated before wide-range utilization of the technology. PMID:22397840

  13. Methods for the determination of platinum group elements originating from the abrasion of automotive catalytic converters

    NASA Astrophysics Data System (ADS)

    Bencs, László; Ravindra, Khaiwal; Van Grieken, René

    2003-10-01

    Anthropogenic emission of platinum group elements (PGEs) from the abrasion of automotive catalytic converters into the environment has significantly increased. However, the concentration level of these PGEs (i.e. Pd, Pt, Rh) is still very low in the nature. Accordingly, their determination and speciation in various environmental compartments appears to be a challenging task for analytical chemists. The present review gives an overview of the analytical procedures documented in this particular field of analytical chemistry with a distinctive emphasis on spectrochemical methodology, it being the most sensitive and robust for accomplishing the above analytical task.

  14. Catalytic converters for exhaust emission control of commercial equipment powered by internal combustion engines.

    PubMed Central

    Cohn, J G

    1975-01-01

    The development of PTX, monolithic catalytic exhaust purifiers, is outlined, and their first use for exhaust emissions control of commercial equipment is described. The main use of PTX converters is on forklift trucks. The purification achievable with PTX-equipped fork-lift trucks under various operational conditions is discussed, and examples from the field are given. During more than ten years of operation, no adverse health effects have been reported, and PTX-equipped internal combustion engines appear safe for use in confined areas. PMID:50933

  15. Catalytic hydrosolvation process converts coal to low-sulfur liquid fuel

    NASA Technical Reports Server (NTRS)

    Qader, S. A.

    1978-01-01

    Development of the catalytic hydrosolvation process for converting coal to low-sulfur fuel oil is described in this paper. Coal impregnated with catalyst was slurried with oil, and the mixture was hydrogenated at a temperature of 475 C, and 30 min residence time under 3600 psi pressure. A ton of coal yielded 3.5 bbl of fuel oil containing 0.2% sulfur, with naphtha and C1-C4 hydrocarbon gases as byproducts. A preliminary economic evaluation of the process indicated potential for further development.

  16. Kinetic studies of competitive adsorption processes related to automobile catalytic converters

    SciTech Connect

    Zaera, F.; Paffett, M.T.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The goal of this project was to study the microscopic details for the adsorption of CO, NO, and O{sub 2} on transition metal surfaces under conditions resembling those present in automobile catalytic converters. Initial sticking coefficients were measured as a function of temperature on transition metal single crystals by using a method originally developed by King and Wells. These measurements were performed under conditions emulating those typical of competitive adsorption, namely, where the substrate is exposed to a mixture of two or more gases simultaneously, or where one molecule is adsorbed on the surface prior to exposure to the second gas. The experimental results were then analyzed by using Monte Carlo computer simulation algorithm in an attempt to better understand the relevant aspects of the adsorption process.

  17. A theoretical study for one-dimensional modeling for VOC in a catalytic converter

    NASA Astrophysics Data System (ADS)

    Chauhan, S.; Sharma, L.; Srivastava, V. K.

    2010-07-01

    Modeling for catalytic oxidation of a volatile organic compound, acetaldehyde for the purpose of controlling tail-pipe emissions from vehicular exhaust was carried out. The model developed was one-dimensional unsteady state model, using mass and energy balance equations to predict results for acetaldehyde conversion in an adiabatic monolith operating under warm-up conditions. The equations consisted of a set of partial differential equations that are coupled and solved using Backward Implicit Scheme. Analysis of the behavior of the converter during warm up period was carried out and it was observed that the warm up was faster for a fresh catalyst and this warm up period could be reduced by introducing hot incoming exhaust gas at higher temperature.

  18. Integrated catalytic process to directly convert furfural to levulinate ester with high selectivity.

    PubMed

    Chen, Bingfeng; Li, Fengbo; Huang, Zhijun; Lu, Tao; Yuan, Yin; Yuan, Guoqing

    2014-01-01

    Levulinic acid is an important platform molecule from biomass-based renewable resources. A sustainable manufacturing process for this chemical and its derivatives is the enabling factor to harness the renewable resource. An integrated catalytic process to directly convert furfural to levulinate ester was developed based on a bifunctional catalyst of Pt nanoparticles supported on a ZrNb binary phosphate solid acid. The hydrogenation of furfural and the following alcoholysis of furfuryl alcohol were performed over this catalyst in a one-pot conversion model. Mesoporous ZrNb binary phosphate was synthesized by a sol-gel method and had a high surface area of 170.1 m(2) g(-1) and a large average pore size of around 8.0 nm. Pt nanoparticles remained in a monodisperse state on the support, and the reaction over Pt/ZrNbPO4 (Pt loading: 2.0 wt%; Zr/Nb, 1:1) gave a very high selectivity to levulinate derivatives (91% in total). The sustainability of this conversion was greatly improved by the process intensification based on the new catalyst, mild reaction conditions, cost abatement in separation and purification, and utilization of green reagents and solvents. PMID:24194497

  19. Oxidative destruction of biomolecules by gasoline engine exhaust products and detoxifying effects of the three-way catalytic converter.

    PubMed

    Blaurock, B; Hippeli, S; Metz, N; Elstner, E F

    1992-01-01

    Aqueous solutions of engine exhaust condensation products were derived from cars powered by diesel or four-stroke gasoline engines (with and without three-way catalytic converter). The cars were operated on a static test platform. Samples of the different exhaust solutions accumulated in a Grimmer-type distillation trap (VDI 3872) during standard test programs (Federal Test Procedure) were incubated with important biomolecules. As indicators of reactive oxygen species or oxidative destruction, ascorbic acid, cysteine, glutathione, serum albumin, the enzymes glycerinaldehyde phosphate dehydrogenase and xanthine oxidase, and the oxygen free-radical indicator keto-methylthiobutyrate were used. During and after the incubations, oxygen activation (consumption) and oxidative destruction were determined. Comparison of the oxidative activities of the different types of exhaust condensates clearly showed that the exhaust condensate derived from the four-stroke car equipped with a three-way catalytic converter exhibited by far the lowest oxidative and destructive power. PMID:1283938

  20. Effect of the Sequence of the Thermoelectric Generator and the Three-Way Catalytic Converter on Exhaust Gas Conversion Efficiency

    NASA Astrophysics Data System (ADS)

    Su, Chuqi; Tong, Naiqiang; Xu, Yuman; Chen, Shan; Liu, Xun

    2013-07-01

    The potential for thermoelectric exhaust heat recovery in vehicles has increased with recent improvements in the efficiency of thermoelectric generators (TEGs). The problem with using thermoelectric generators for vehicle applications is whether the device is compatible with the original vehicle exhaust system, which determines the quality of the exhaust gas treatment and the realization of energy conservation and emission reduction. Based on ANSYS CFX simulation analysis of the impact of two positional relationships between the TEG and three-way catalytic converter in the exhaust system on the working efficiency of both elements, it is concluded that the layout with the front three-way catalytic converter has an advantage over the other layout mode under current conditions. New ideas for an improvement program are proposed to provide the basis for further research.

  1. DESIGN NOTE: A compact catalytic converter for the production of para-hydrogen

    NASA Astrophysics Data System (ADS)

    Juarez, A. M.; Cubric, D.; King, G. C.

    2002-05-01

    The design and operation of a compact converter to produce a constant flow of para-hydrogen from normal hydrogen is described. The converter features a paramagnetic compound (nickel sulfate) that catalyses the conversion of ortho- to para-hydrogen at temperatures of 14-21 K. The converter has been tested by measuring rotationally resolved photoelectron spectra in the para-hydrogen produced. The percentage of the para-hydrogen species in the converted gas was determined to be >97%.

  2. Monocyte Tumor Necrosis Factor-α–Converting Enzyme Catalytic Activity and Substrate Shedding in Sepsis and Noninfectious Systemic Inflammation*

    PubMed Central

    O’Callaghan, David J. P.; O’Dea, Kieran P.; Scott, Alasdair J.; Takata, Masao

    2015-01-01

    Objectives: To determine the effect of severe sepsis on monocyte tumor necrosis factor-α–converting enzyme baseline and inducible activity profiles. Design: Observational clinical study. Setting: Mixed surgical/medical teaching hospital ICU. Patients: Sixteen patients with severe sepsis, 15 healthy volunteers, and eight critically ill patients with noninfectious systemic inflammatory response syndrome. Interventions: None. Measurements and Main Results: Monocyte expression of human leukocyte antigen-D-related peptide, sol-tumor necrosis factor production, tumor necrosis factor-α–converting enzyme expression and catalytic activity, tumor necrosis factor receptor 1 and 2 expression, and shedding at 48-hour intervals from day 0 to day 4, as well as p38-mitogen activated protein kinase expression. Compared with healthy volunteers, both sepsis and systemic inflammatory response syndrome patients’ monocytes expressed reduced levels of human leukocyte antigen-D-related peptide and released less sol-tumor necrosis factor on in vitro lipopolysaccharide stimulation, consistent with the term monocyte deactivation. However, patients with sepsis had substantially elevated levels of basal tumor necrosis factor-α–converting enzyme activity that were refractory to lipopolysaccharide stimulation and this was accompanied by similar changes in p38-mitogen activated protein kinase signaling. In patients with systemic inflammatory response syndrome, monocyte basal tumor necrosis factor-α–converting enzyme, and its induction by lipopolysaccharide, appeared similar to healthy controls. Changes in basal tumor necrosis factor-α–converting enzyme activity at day 0 for sepsis patients correlated with Acute Physiology and Chronic Health Evaluation II score and the attenuated tumor necrosis factor-α–converting enzyme response to lipopolysaccharide was associated with increased mortality. Similar changes in monocyte tumor necrosis factor-α–converting enzyme activity could

  3. The acanthocephalan Paratenuisentis ambiguus as a sensitive indicator of the precious metals Pt and Rh from automobile catalytic converters.

    PubMed

    Sures, B; Zimmermann, S; Sonntag, C; Stüben, D; Taraschewski, H

    2003-01-01

    Recent studies revealed that intestinal acanthocephalans of fish can accumulate heavy metals to concentrations orders of magnitude higher than those in the host tissues or the aquatic environment. This significant heavy metal accumulation by acanthocephalans, even surpassing that of established free living accumulation bioindicators, encouraged us to study the bioavailability of the platinum-group-metals (PGM) Pt and Rh for parasites. These precious metals are used in catalytic converters of cars for exhaust gas purification in Europe since the early 1980s. In addition to the beneficial effect in reducing the emission of CHx, CO and NOx of cars there is an increasing emission of these metals. However, it still remains unclear if these elements become accumulated in the biosphere and whether they affect the health of organisms. The present study reveals that in European eels (Anguilla anguilla) naturally infected with the eoacanthocephalan parasite Paratenuisentis ambiguus and experimentally exposed to ground catalytic converter material, the parasites take up and accumulate the catalytic active metals Pt and Rh whereas in the examined host tissues we found no metal uptake. Compared with the PGM concentrations in the water the worms contained 1600 times higher Rh and 50 times higher Pt concentrations. Thus, the parasites can be used as sentinel organisms reflecting even very low levels of precious metals. PMID:12547529

  4. Research on Integration of an Automotive Exhaust-Based Thermoelectric Generator and a Three-Way Catalytic Converter

    NASA Astrophysics Data System (ADS)

    Deng, Y. D.; Chen, Y. L.; Chen, S.; Xianyu, W. D.; Su, C. Q.

    2015-06-01

    A key research topic related to thermoelectric generators (TEGs) for automotive applications is to improve their compatibility with the original vehicle exhaust system, which determines the quality of the exhaust gas treatment and the realization of energy conservation and emission reduction. A new TEG integrated with a three-way catalytic converter (CTEG) by reshaping the converter as the heat exchanger is proposed. A heat-flux coupling simulation model of the integrated TEG is established at the light-off stage of the original three-way catalytic converter (TWC). Temperature distribution maps of the integrated heat exchanger, thermoelectric modules, and cooling-water tank are obtained to present the process of energy flow among the parts of the CTEG. Based on the simulation results, the output power of the CTEG is calculated by a mathematical model. A minimum output power of 31.93 W can be obtained by conversion when the TWC starts working at steady conditions. Theoretically, this case study demonstrates the great potential for use of CTEGs in vehicles.

  5. Platinum levels in natural and urban soils from Rome and Latium (Italy): significance for pollution by automobile catalytic converter.

    PubMed

    Cinti, D; Angelone, M; Masi, U; Cremisini, C

    2002-07-01

    Platinum concentrations in topsoil samples collected in 1992 (48) and in 2001 (16) from the urban area of Rome have been determined by ICP-MS. Concentrations in 47 soil samples collected in 1992 from natural sites of Latium (an area around Rome) have been determined for a first assessment of natural background levels. The Pt concentrations in Rome urban soils collected in 1992 range from 0.8 to 6.3 ng/g (mean = 3.8 +/- 1.0) overlapping the concentration range of natural soils from Latium (mean = 3.1 +/- 2.1 ng/g). No significant correlation has generally been found between Pt contents in the 'natural' soils and related bedrock or major pedogenetic parameters. These results suggest that there is no evidence of Pt pollution in Rome urban soils at that time, because the massive use of the automobile catalytic converter has only just started. Higher (up to six times more) Pt concentrations, than those measured in the 1992 samples, have been measured, in some cases, in Rome urban soils collected in 2001, suggesting a possible start of Pt accumulation because of the large-scale use in the last decade of automobile catalytic converters. At the same time, a clear decrease of lead levels in Rome urban soils with respect to the levels measured in 1992 has been observed, paralleling the decreasing number of lead gasoline-fuelled cars. Here we present one of the first systematic studies for defining background levels of Pt in Italian natural soils, thus allowing for monitoring, in the future, should any possible Pt pollution caused by the use of automobile catalytic converter, especially in urban soils, occur. PMID:12109480

  6. Evaluation of four sample treatments for determination of platinum in automotive catalytic converters by graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Puig, Ana I.; Alvarado, José I.

    2006-09-01

    Conventional and microwave assisted digestion, both using aqua regia, alkaline fusion with lithium metaborate and aqueous slurries were evaluated as sample treatments for determination of Pt in automotive catalytic converters by Graphite Furnace Atomic Absorption Spectrometry (GF-AAS). Determination of platinum by GF-AAS in samples of the catalytic converter's substrates, prepared by the four methods described, indicates that the highest platinum concentration i.e. maximum Pt extraction in the range of 748 ± 15-998 ± 10 μg mL - 1 , is obtained for samples dissolved by alkaline fusion, closely followed by analysis of aqueous plus Triton X-100 slurries 708 ± 14-958 ± 10 μg mL - 1 , while neither one of the acid digestion procedures achieved total dissolution of the samples. Slurry analysis is thus shown to be a viable alternative and is recommended, based on its speed and ease of implementation. Aqueous standards calibration curves and the standard addition methods were also compared. The results showed that no appreciable matrix effects are present, regardless of the sample preparation procedure used. Precision of the measurements, expressed as percentage relative standard deviation, ranged between 2.5 to 4.9%. Accuracy of the results was assessed by recovery tests which rendered values between 98.9 and 100.9%.

  7. Characterization and application of an externally mounted catalytic converter for aircraft measurements of NOy

    NASA Astrophysics Data System (ADS)

    Lange, L.; Fischer, H.; Parchatka, U.; Gurk, C.; Zenker, T.; Harris, G. W.

    2002-08-01

    A novel design for an airborne NOy converter was implemented, characterized in the laboratory, and used extensively for in situ tropospheric and stratospheric measurements of total reactive nitrogen (NOy). During field deployments, the converter is mounted outside the aircraft fuselage, avoiding the need for an inlet line. In flight, the converter can be calibrated by the addition of standard gases close to the sample inlet, compensating for any changes in the instrument sensitivity caused by changing operating conditions. The system has been used successfully during several Stratosphere Troposphere Experiments by Aircraft Measurements campaigns in the lowermost stratosphere and upper troposphere for the measurement of total reactive nitrogen. The detection limit of the system is approximately 100 pptv for 10 s integrated data (2σ). The precision, deduced from the reproducibility of the in-flight calibrations, is 7% and the accuracy is about 30%. Laboratory studies demonstrate that interference from HCN, NH3, and CH3CN is negligible for background conditions.

  8. Traffic and catalytic converter - related atmospheric contamination in the metropolitan region of the city of Rio de Janeiro, Brazil.

    PubMed

    da Silva, Lílian Irene Dias; de Souza Sarkis, Jorge Eduardo; Zotin, Fátima Maria Zanon; Carneiro, Manuel Castro; Neto, Arnaldo Alcover; da Silva, Alzira dos Santos Amaral Gomes; Cardoso, Mauri José Baldini; Monteiro, Maria Inês Couto

    2008-03-01

    In this work, 24-h PM10 samples were collected in Rio de Janeiro, Brazil, and analysed for trace elements (Cd, Ce, Cu, La, Mo, Ni, Pb, Pd, Rh, Sb and Sn). The sampling was carried out at five locations (Bonsucesso; Centro, downtown city; Copacabana; Nova Iguaçu and Sumaré) with different traffic densities and anthropogenic activities. An analytical method based on the EPA method for the determination of trace elements in airborne particulate matter (PM), using ultrasonic-assisted extraction and inductively coupled plasma mass spectrometry (ICP-MS) was applied. Our results suggest that vehicular traffic is the most important source of environmental pollution at the studied sites. The presence of Mo, Pd and Rh in the analysed filters reflects an additional source of pollution caused by the erosion and deterioration of automotive catalytic converters. PMID:18082244

  9. New data on the mobility of Pt emitted from catalytic converters.

    PubMed

    Fliegel, Daniel; Berner, Zsolt; Eckhardt, Detlef; Stüben, Doris

    2004-05-01

    The mobility and speciation of Pt was investigated in dust deposited in highway tunnels and in gully sediments. For this, a sequential extraction technique was used in combination with a microwave digestion procedure, followed by detection of Pt with high resolution ICP-MS. A digestion procedure using HNO(3)/HCl/H(2)O(2) was developed and its efficiency tested for environmental materials. Total Pt contents ranged from approximately 100 to 300 microg/kg. The high share of chemically mobile Pt in the tunnel dust (up to about 40%) indicates that Pt is predominantly emitted in a mobile form from the converter. The absence of a mobile fraction in the gully sediment is explained by the elution of Pt by run-off. Except for the mobile and easily mobilised fractions none of the other fractions of the sequential extraction contains Pt, neither in the dust samples nor in the gully sediment. PMID:15007592

  10. Catalytic properties of recombinant dipeptidyl carboxypeptidase from Escherichia coli: a comparative study with angiotensin I-converting enzyme.

    PubMed

    Cunha, Carlos Eduardo L; Magliarelli, Helena de Fátima; Paschoalin, Thaysa; Nchinda, Aloysius T; Lima, Jackson C; Juliano, Maria A; Paiva, Paulo B; Sturrock, Edward D; Travassos, Luiz R; Carmona, Adriana K

    2009-09-01

    Dipeptidyl carboxypeptidase from Escherichia coli (EcDcp) is a zinc metallopeptidase with catalytic properties closely resembling those of angiotensin I-converting enzyme (ACE). However, EcDcp and ACE are classified in different enzyme families (M3 and M2, respectively) due to differences in their primary sequences. We cloned and expressed EcDcp and studied in detail the enzyme's S(3) to S(1)' substrate specificity using positional-scanning synthetic combinatorial (PS-SC) libraries of fluorescence resonance energy transfer (FRET) peptides. These peptides contain ortho-aminobenzoic acid (Abz) and 2,4-dinitrophenyl (Dnp) as donor/acceptor pair. In addition, using FRET substrates developed for ACE [Abz-FRK(Dnp)P-OH, Abz-SDK(Dnp)P-OH and Abz-LFK(Dnp)-OH] as well as natural ACE substrates (angiotensin I, bradykinin, and Ac-SDKP-OH), we show that EcDcp has catalytic properties very similar to human testis ACE. EcDcp inhibition studies were performed with the ACE inhibitors captopril (K(i)=3 nM) and lisinopril (K(i)=4.4 microM) and with two C-domain-selective ACE inhibitors, 5-S-5-benzamido-4-oxo-6-phenylhexanoyl-L-tryptophan (kAW; K(i)=22.0 microM) and lisinopril-Trp (K(i)=0.8 nM). Molecular modeling was used to provide the basis for the differences found in the inhibitors potency. The phylogenetic relationship of EcDcp and related enzymes belonging to the M3 and M2 families was also investigated and the results corroborate the distinct origins of EcDcp and ACE. PMID:19558329

  11. The effects of the catalytic converter and fuel sulfur level on motor vehicle particulate matter emissions: gasoline vehicles.

    PubMed

    Maricq, M Matti; Chase, Richard E; Xu, Ning; Podsiadlik, Diane H

    2002-01-15

    Scanning mobility and electrical low-pressure impactor particle size measurements conducted during chassis dynamometer testing reveal that neither the catalytic converter nor the fuel sulfur content has a significant effect on gasoline vehicle tailpipe particulate matter (PM) emissions. For current technology, port fuel injection, gasoline engines, particle number emissions are < or = 2 times higher from vehicles equipped with blank monoliths as compared to active catalysts, insignificant in contrast to the 90+% removal of hydrocarbons. PM mass emission rates derived from the size distributions are equal within the experimental uncertainty of 50-100%. Gravimetric measurements exhibit a 3-10-fold PM mass increase when the active catalyst is omitted, which is attributed to gaseous hydrocarbons adsorbing onto the filter medium. Both particle number and gravimetric measurements show that gasoline vehicle tailpipe PM emissions are independent (within 2 mg/mi) of fuel sulfur content over the 30-990 ppm concentration range. Nuclei mode sulfate aerosol is not observed in either test cell measurements or during wind tunnel testing. For three-way catalyst equipped vehicles, the principal sulfur emission is SO2; however a sulfur balance is not obtained over the drive cycle. Instead, sulfur is stored on the catalyst during moderate driving and then partially removed during high speed/load operation. PMID:11827063

  12. Implications of platinum-group element accumulation along U.S. roads from catalytic-converter attrition.

    PubMed

    Ely, J C; Neal, C R; Kulpa, C F; Schneegurt, M A; Seidler, J A; Jain, J C

    2001-10-01

    Automobile catalytic converters are dispersing platinum-group elements (PGEs) Rh, Pt, and Pd into the environment (1-3). This paper represents the first detailed study to assess the PGE content of soils and grasses from U.S. roadsides. These soils were analyzed using cation exchange pretreatment and ultrasonic nebulizer-ICP-MS (4). Highway and several urban sites showed Pt abundances of 64-73 ng/g immediately adjacent to the roadside, with corresponding Pd and Rh abundances of 18-31 ng/g and 3-7 ng/g, respectively. All Pt and most Pd and Rh abundances are statistically above local background soil values. Platinum, Rd, and Rh show positive correlations with traffic-related elements (Ni, Cu, Zn, and Pb) but no correlations with nontraffic-related elements (Y, Ga). Iridium and Ru show no correlations with any of these trace elements. These PGE abundances are comparable to European studies (5-7) and are approaching concentrations that would be economically viable to recover. This study also demonstrates transport of Pt statistically above background more than 50 m from the roadside. Further study is necessary to see how mobile the PGEs are in roadside environments, but these initial data indicate only Pt is taken up by plants. PMID:11642438

  13. Roadside Accumulation of Pt, Pd, Rh and Other Trace Elements From Automobiles: Catalytic Converter Attrition and Platinum-Group Element Mobility in the Roadside Environment.

    NASA Astrophysics Data System (ADS)

    Ely, J. C.; Dahlheimer, S. R.; Neal, C. R.

    2003-12-01

    Elemental abundances of Pt, Pd and Rh have been documented across the industrialized world in roadside environments due to attrition of automotive catalytic converters (Zereini and Alt, 2000, Anthropogenic PGE Emissions, Springer, 308pp; Ely et al., 2001, EnvSci&Tech, 35:3816-3822; Whiteley and Murray, 2003, SciTotEnv, in press). In our ongoing study, the highest reported roadside Pt abundance 1.8 ppm has been found immediately adjacent to the road at a field site in South Bend, IN, USA. Furthermore, initial studies show positive correlations of Pt, Pd and Rh with some trace elements (Ni, Cu, Zn and Pb), which has been confirmed by further analysis for these and other elements (Ce, Cr). It has been demonstrated that elements such as Ce are present in catalytic converters at concentrations of 100's ppm to 3-wt.%. These elements are also being attrited with Pt, Pd and Rh and aerially transported and deposited. Our field site was established next to US-933 adjacent to the Notre Dame campus. Areas were cleared of the top 2-4 cm of soil (removing surficial Pt, Pd and Rh) at 1, 5, 10 and 50 meters from the roadside. Within 3 months the 1-meter site contained 67% of the initial Rh and Pt concentrations and 100% of the initial Pd concentration. The sites at 5, 10 and 50 meters showed similar results, in some cases exceeding the initial concentrations. After 6 months the concentrations of Pt, Pd and Rh were all within error of the initial concentrations, indicating steady state abundances had probably been reached. Grass samples from each site showed that washed vs. unwashed samples were within error of each other, and there may be a slight enrichment (approx. 1 ppb) in the grasses of Pd and Pt, but this enrichment was independent of distance from the road. The steady-state situation suggests that the PGEs are being removed from the immediate roadside environment, which requires that the metals are being oxidized and/or complexed in such a way to facilitate transport. The

  14. Three-dimensional distribution analysis of platinum, palladium and rhodium in auto catalytic converters using imaging-mode laser-induced breakdown spectrometry

    NASA Astrophysics Data System (ADS)

    Lucena, Patricia; Laserna, J. Javier

    2001-02-01

    Laser-induced breakdown spectrometry (LIBS) is reported here as an effective technique to describe the volume distribution of platinum, rhodium and palladium in catalytic converters installed in motor vehicles. Using the second harmonic output of a Nd:YAG laser and a CCD-based atomic emission spectrometer, LIBS is used in multielemental, imaging-mode to permit the simultaneous analysis of the several elements present in the converter, including the internal standard. The data are reported with a lateral resolution of 1.75 mm over a fresh catalytic structure which is 128 mm long. The concentrational variability of the platinum group metals (PGMs) varies in the range ˜3-23% relative standard deviation depending on the element, the substrate and the direction investigated. The causes of the dispersion observed are discussed.

  15. Accumulation of the precious metals platinum, palladium and rhodium from automobile catalytic converters in Paratenuisentis ambiguus as compared with its fish host, Anguilla anguilla.

    PubMed

    Zimmermann, S; von Bohlen, A; Messerschmidt, J; Sures, B

    2005-03-01

    The platinum group metals (PGM) Pt, Pd and Rh are emitted into the environment mainly by catalytic exhaust gas converters of cars. As PGM accumulate in sediments of aquatic ecosystems, the study was focused on the uptake of the noble metals by European eels, Anguilla anguilla infected with the acanthocephalan Paratenuisentis ambiguus. Eels were exposed to ground catalytic converter material for six weeks. After exposure Pt and Pd were detected in the liver and kidney of the eels and in the parasites. Palladium was also found in fish muscle and intestine. No Rh uptake by the eel tissues and the parasites occurred. Paratenuisentis ambiguus contained the highest levels of both metals with 40 times higher Pt concentrations and four times higher Pd concentrations than the liver of its host. Due to its accumulation capacity for PGM, P. ambiguus can be applied as a sensitive accumulation indicator in field studies to assess the degree of environmental PGM contamination in aquatic ecosystems. PMID:15831118

  16. Environmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine catalytic converters.

    PubMed

    Moldovan, M; Palacios, M A; Gómez, M M; Morrison, G; Rauch, S; McLeod, C; Ma, R; Caroli, S; Alimonti, A; Petrucci, F; Bocca, B; Schramel, P; Zischka, M; Pettersson, C; Wass, U; Luna, M; Saenz, J C; Santamaría, J

    2002-09-16

    A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80,000 km. Two were gasoline engine catalysts (Pt-Pd-Rh and Pd-Rh), while the other two were diesel engine catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing, and the sample collection device used allowed differentiation between the particulate and soluble fractions, the latter being the most relevant from an environmental point of view. Analyses were performed by inductively coupled plasma-mass spectrometry (ICP-MS) (quadrupole and high resolution), and special attention was paid to the control of spectral interference, especially in the case of Pd and Rh. The results obtained show that, for fresh catalysts, the release of particulate PGE through car exhaust fumes does not follow any particular trend, with a wide range (one-two orders of magnitude) for the content of noble metals emitted. The samples collected from 30,000-80,000 km present a more homogeneous PGE release for all catalysts studied. A decrease of approximately one order of magnitude is observed with respect to the release from fresh catalysts, except in the case of the diesel engine catalyst, for which PGE emission continued to be higher than in the case of gasoline engines. The fraction of soluble PGE was found to represent less than 10% of the total amount released from fresh catalysts. For aged catalysts, the figures are significantly higher, especially for Pd and Rh. Particulate PGE can be considered as virtually biologically inert, while soluble PGE forms can represent an environmental risk due to their bioavailability, which leads them to accumulate in the environment. PMID:12398337

  17. Effect of support on a catalytic converter for removing CO and HC emissions from a two-stroke motorcycle

    SciTech Connect

    Lee, C.H.; Chen, Y.W.

    1997-12-01

    The effect of support on the noble metal catalysts for carbon monoxide and hydrocarbon oxidation was investigated. The reactions were performed under the stoichiometric and oxygen-deficient conditions. Under the stoichiometric point, the activities of the powder catalysts for CO and C{sub 3}H{sub 6} oxidation are in the order Pt/K{sub 2}O/Al{sub 2}O{sub 3} > Pt/Al{sub 2}O{sub 3} > Pt/Al{sub 2}O{sub 3}-SiO{sub 2}, that is, the same as the order of basicity of these catalysts. Under an oxygen-deficient condition, Pt supported on an acidic support, Al{sub 2}O{sub 3}-SiO{sub 2}, exhibits the higher C{sub 3}H{sub 6} conversion and the higher activity for the steam re-forming reaction. In contrast, Pt supported on a basic support, K{sub 2}O/Al{sub 2}O{sub 3}, exhibits the higher CO conversion and the higher activity for the water-gas shift reaction. The order of activity of the powder catalysts for the water-gas shift reaction is the same as the order of basicity of these catalysts. On the other hand, the testing results of the monolithic PtRh-containing catalysts by the simulative gases and the ECE-40 mode driving cycle also reveal the same trend as that of the Pt powder catalysts. Furthermore, the addition of K{sub 2}O on PtRh/Al{sub 2}O{sub 3}-CeO{sub 2} not only increases the basicity of the catalyst but also significantly reduces the CO emission under the ECE-40 mode driving cycle test. Therefore, K{sub 2}O could be a promising additive to a catalytic converter of a two-stroke motorcycle since it can significantly enhance CO conversion.

  18. Peptidase specificity characterization of C- and N-terminal catalytic sites of angiotensin I-converting enzyme.

    PubMed

    Araujo, M C; Melo, R L; Cesari, M H; Juliano, M A; Juliano, L; Carmona, A K

    2000-07-25

    Quenched fluorescence peptides were used to investigate the substrate specificity requirements for recombinant wild-type angiotensin I-converting enzyme (ACE) and two full-length mutants bearing a single functional active site (N- or C-domain). We assayed two series of bradykinin-related peptides flanked by o-aminobenzoic acid (Abz) and N-(2,4-dinitrophenyl)ethylenediamine (EDDnp), namely, Abz-GFSPFXQ-EDDnp and Abz-GFSPFRX-EDDnp (X = natural amino acids), in which the fluorescence appeared when Abz/EDDnp are separated by substrate hydrolysis. Abz-GFSPFFQ-EDDnp was preferentially hydrolyzed by the C-domain while Abz-GFSPFQQ-EDDnp exhibits higher N-domain specificity. Internally quenched fluorescent analogues of N-acetyl-SDKP-OH were also synthesized and assayed. Abz-SDK(Dnp)P-OH, in which Abz and Dnp (2,4-dinitrophenyl) are the fluorescent donor-acceptor pair, was cleaved at the D-K(Dnp) bond with high specificity by the ACE N-domain (k(cat)/K(m) = 1.1 microM(-)(1) s(-)(1)) being practically resistant to hydrolysis by the C-domain. The importance of hydroxyl-containing amino acids at the P(2) position for N-domain specificity was shown by performing the kinetics of hydrolysis of Abz-TDK(Dnp)P-OH and Abz-YDK(Dnp)P-OH. The peptides Abz-YRK(Dnp)P-OH and Abz-FRK(Dnp)P-OH which were hydrolyzed by wild-type ACE with K(m) values of 5.1 and 4.0 microM and k(cat) values of 246 and 210 s(-)(1), respectively, have been shown to be excellent substrates for ACE. The differentiation of the catalytic specificity of the C- and N-domains of ACE seems to depend on very subtle variations on substrate-specific amino acids. The presence of a free C-terminal carboxyl group or an aromatic moiety at the same substrate position determines specific interactions with the ACE active site which is regulated by chloride and seems to distinguish the activities of both domains. PMID:10913258

  19. N- vs. C-Domain Selectivity of Catalytic Inactivation of Human Angiotensin Converting Enzyme by Lisinopril-Coupled Transition Metal Chelates

    PubMed Central

    Hocharoen, Lalintip; Joyner, Jeff C.; Cowan, J. A.

    2014-01-01

    The N- and C-terminal domains of human somatic Angiotensin I Converting Enzyme (sACE-1) demonstrate distinct physiological functions, with resulting interest in the development of domain-selective inhibitors for specific therapeutic applications. Herein, the activity of lisinopril-coupled transition metal chelates were tested for both reversible binding and irreversible catalytic inactivation of sACE-1. C/N domain binding selectivity ratios ranged from 1 to 350, while rates of irreversible catalytic inactivation of the N- and C-domains were found to be significantly greater for the N-domain, suggesting a more optimal orientation of the M-chelate-lisinopril complexes within the active site of the N-domain of sACE-1. Finally, the combined effect of binding selectivity and inactivation selectivity was assessed for each catalyst (double-filter selectivity factors), and several catalysts were found to cause domain-selective catalytic inactivation. The results of this study demonstrate the ability to optimize the target selectivity of catalytic metallopeptides through both binding and orientation factors (double-filter effect). PMID:24228790

  20. Oxidative leaching process with cupric ion in hydrochloric acid media for recovery of Pd and Rh from spent catalytic converters.

    PubMed

    Nogueira, C A; Paiva, A P; Oliveira, P C; Costa, M C; da Costa, A M Rosa

    2014-08-15

    The recycling of platinum-group metals from wastes such as autocatalytic converters is getting growing attention due to the scarcity of these precious metals and the market pressure originated by increase of demand in current and emerging applications. Hydrometallurgical treatment of such wastes is an alternative way to the most usual pyrometallurgical processes based on smelter operations. This paper focuses on the development of a leaching process using cupric chloride as oxidising agent, in HCl media, for recovery of palladium and rhodium from a spent catalyst. The chloride media allows the adequate conditions for oxidising and solubilising the metals, as demonstrated by equilibrium calculations based on thermodynamic data. The experimental study of the leaching process revealed that Pd solubilisation is clearly easier than that of Rh. The factors temperature, time, and HCl and Cu(2+) concentrations were significant regarding Pd and Rh leaching, the latter requiring higher factor values to achieve the same results. Leaching yields of 95% Pd and 86% Rh were achieved under optimised conditions (T = 80 °C, t = 4h, [HCl] = 6M, [Cu(2+)] = 0.3M). PMID:24953939

  1. In situ deposition of silver and palladium nanoparticles prepared by the polyol process, and their performance as catalytic converters of automobile exhaust gases

    NASA Astrophysics Data System (ADS)

    Bonet, F.; Grugeon, S.; Herrera Urbina, R.; Tekaia-Elhsissen, K.; Tarascon, J.-M.

    2002-04-01

    In situ deposition of silver particles onto alumina and palladium particles onto mixed CeZr oxides has been achieved upon chemical reduction of the corresponding metal species (AgNO 3 and PdCl 2) by ethylene glycol in the presence of polyvinylpyrrolidone. The support oxide powders were found to keep their crystalline structure and morphology after treatment with hot ethylene glycol while the BET surface area decreased after metal deposition. Microprobe maps obtained from energy dispersive X-ray analysis revealed a homogeneous distribution of metal nanoparticles on the surfaces of alumina and of the mixed CeZr oxides. Supported silver and palladium were tested as catalytic converters of simulated exhaust automobile gases. The catalytic activity of silver-loaded alumina powder catalyst for CO and hydrocarbon oxidation as well as NO and NO x reduction, was found to be higher than that of a reference silver catalyst. Palladium-loaded mixed CeZr oxides powder catalyst showed a similar performance to that of a reference palladium catalyst as a three-way catalyst converter.

  2. Axial characterization of lightoff and underfloor catalytic converters vehicle-aged on a 5.8 L Corvette

    SciTech Connect

    Beck, D.D.; Monroe, D.R.; DiMaggio, C.L.; Sommers, J.W.

    1995-12-31

    Catalysts taken from the lightoff and underfloor converters of two 1986 Corvette exhaust systems which had been vehicle-aged for 100,000+ miles were cut into 1 inch thick sections along their axis and characterized for lean lightoff and warmed-up performance using a laboratory reactor. Sections were then treated to remove the poisons, and the characterization was repeated. An axial gradient in both lightoff and warmed-up conversion efficiency for HC and CO was, detected within the first 2 inches of both lightoff converters for both vehicles. This activity gradient is in agreement with the gradient in the phosphorus and zinc concentrations found in the front 2--3 inch sections of the lightoff converters. Comparison of these data sets with those obtained after removal of the P and Zn poisons led the authors to conclude that a significant part of the total deterioration of activity can be attributed to phosphorus and zinc poisoning for the front 1 inch (and to a lesser extent for the second 1 inch section) of the lightoff converters.

  3. Influence of fuel properties, nitrogen oxides, and exhaust treatment by an oxidation catalytic converter on the mutagenicity of diesel engine emissions.

    PubMed

    Bünger, Jürgen; Krahl, Jürgen; Weigel, Andreas; Schröder, Olaf; Brüning, Thomas; Müller, Michael; Hallier, Ernst; Westphal, Götz

    2006-08-01

    Particle emissions of diesel engines (DEP) content polycyclic aromatic hydrocarbons (PAH) these compounds cause a strong mutagenicity of solvent extracts of DEP. We investigated the influence of fuel properties, nitrogen oxides (NO( x )), and an oxidation catalytic converter (OCC) on the mutagenic effects of DEP. The engine was fuelled with common diesel fuel (DF), low-sulphur diesel fuel (LSDF), rapeseed oil methyl ester (RME), and soybean oil methyl ester (SME) and run at five different load modes in two series with and without installation of an OCC in the exhaust pipe. Particles from the cooled and diluted exhaust were sampled onto glass fibre filters and extracted with dichloromethane in a soxhlet apparatus. The mutagenicity of the extracts was tested using the Salmonella typhimurium/mammalian microsome assay with tester strains TA98 and TA100. Without OCC the number of revertant colonies was lower in extracts of LSDF than in extracts of DF. The lowest numbers of revertant colonies were induced by the plant oil derived fuels. In three load modes, operation with the OCC led to a reduction of the mutagenicity. However, direct mutagenic effects under heavy duty conditions (load mode A) were significantly increased for RME (TA98, TA100) and SME (TA98). A consistent but not significant increase in direct mutagenicity was observed for DF and LSDF at load mode A, and for DF at idling (load mode E) when emissions were treated with the OCC. These results raise concern over the use of oxidation catalytic converters with diesel engines. We hypothesise that the OCC increases formation of direct acting mutagens under certain conditions by the reaction of NO( x ) with PAH resulting in the formation of nitrated-PAH. Most of these compounds are powerful direct acting mutagens. PMID:16555046

  4. Evaluation of an EMITEC resistively heated metal monolith catalytic converter on two M100 neat methanol-fueled vehicles

    NASA Astrophysics Data System (ADS)

    Piotrowski, Gregory K.; Schaefer, Ronald M.

    1992-12-01

    The report describes the evaluation of a resistively heated catalyst system on two different methanol fueled vehicles. The EMITEC catalyst consisted of a compact resistively heated metal monolith in front of a larger conventional main converter. The EMITEC catalyst was evaluated on two neat methanol-fueled vehicles, a 1981 Volkswagen Rabbit and a 1988 Toyota Corolla. Emission testing was conducted over the Federal Test Procedure (FTP) CVS-75 test cycle. The emissions of primary interest were cold start methanol (unburned fuel), carbon monoxide, and formaldehyde.

  5. Effect of K{sub 2}O on a Pd-containing catalytic converter for removing CO and HC emissions from a two-stroke motorcycle

    SciTech Connect

    Lee, C.H.; Chen, Y.W.

    1998-04-01

    Noble metals (Pt, Pd, and Rh) supported on Al{sub 2}O{sub 3}, K{sub 2}/Al{sub 2}O{sub 3}, CeO{sub 2}/Al{sub 2}O{sub 3}, and K{sub 2}O/CeO{sub 2}/Al{sub 2}O{sub 3} were prepared and characterized with respect to surface area, pore volume, and temperature-programmed desorption of CO{sub 2}. The effects of K{sub 2}O on the noble-metal catalysts for carbon monoxide and hydrocarbon oxidation were investigated. The reactions were carried out under the stoichiometric and oxygen-deficient conditions. Under the stoichiometric point, the Pd-containing catalysts exhibit higher activity than the Pt-containing catalysts for both CO and C{sub 3}H{sub 6} oxidation. Moreover, Pd/K{sub 2}O/CeO{sub 2}/Al{sub 2}O{sub 3} is the most active catalyst among the powder catalysts in this study. Under the oxygen-deficient conditions and in the presence of water, the CO conversions on Pd/Al{sub 2}O{sub 3} and Pd/CeO{sub 2}/Al{sub 2}O{sub 3} are significantly lower than those on Pt/Al{sub 2}O{sub 3} and Pt/CeO{sub 2}/Al{sub 2}O{sub 3}, respectively. In contrast, the Pd-containing catalysts exhibit higher C{sub 3}H{sub 6} conversion than the Pt-containing catalysts. However, the CO conversions on the Pd-containing catalysts can be promoted by the addition of K{sub 2}O. On the other hand, the test results of the monolithic catalysts revealed that the CO conversion on PdRh/K{sub 2}O/Al{sub 2}O{sub 3}--CeO{sub 2} is quite close to that on PtRh/Al{sub 2}O{sub 3}-CeO{sub 2} under the simulative gases and the ECE-40 mode driving cycle test. PtRh/Al{sub 2}O{sub 3}-CeO{sub 2} is the typical composition of catalytic converters for two-stroke motorcycles. It infers that PdRh/K{sub 2}O/Al{sub 2}O{sub 3}-CeO{sub 2} is a promising catalytic converter for a two-stroke motorcycle.

  6. Catalytic oxidation of waste materials

    NASA Technical Reports Server (NTRS)

    Jagow, R. B.

    1977-01-01

    Aqueous stream of human waste is mixed with soluble ruthenium salts and is introduced into reactor at temperature where ruthenium black catalyst forms on internal surfaces of reactor. This provides catalytically active surface to convert oxidizable wastes into breakdown products such as water and carbon dioxide.

  7. Uptake and bioaccumulation of platinum group metals (Pd, Pt, Rh) from automobile catalytic converter materials by the zebra mussel (Dreissena polymorpha).

    PubMed

    Zimmermann, Sonja; Messerschmidt, Jürgen; von Bohlen, Alex; Sures, Bernd

    2005-06-01

    The uptake and bioaccumulation of the platinum group metals (PGM) platinum (Pt), palladium (Pd), and rhodium (Rh) by the zebra mussel (Dreissena polymorpha) were investigated in exposure studies using ground material from unused automobile catalytic converters as metal source. The mussels were exposed to the metals in tap water or humic water. In the soft tissue samples of exposed mussels mean Pt levels ranged in dependence on the type of tank water and the exposure period (6, 9, or 18 weeks) between 780 and 4300 ng/g, the Pd levels ranged between 720 and 6300 ng/g, and the Rh levels ranged between 270 and 1900 ng/g. In contrast, the control mussels had metal concentrations of <20 ng/g (Pt), <50 ng/g (Pd), and <40 ng/g (Rh). Considerably higher PGM levels were found in the exposed mussels of the humic water group than in those of the tap water group. Although there is a cumulative increase of the PGM concentrations in the environment since the introduction of the automobile catalyst more than 20 years ago, only little information about the PGM contamination in the biosphere, especially the fauna, is available. Due to the high capacity of D. polymorpha to accumulate PGM, this bivalve could be used as a potential sentinel for monitoring the noble metals in aquatic ecosystems. PMID:15820726

  8. Raney nickel catalytic device

    DOEpatents

    O'Hare, Stephen A.

    1978-01-01

    A catalytic device for use in a conventional coal gasification process which includes a tubular substrate having secured to its inside surface by expansion a catalytic material. The catalytic device is made by inserting a tubular catalytic element, such as a tubular element of a nickel-aluminum alloy, into a tubular substrate and heat-treating the resulting composite to cause the tubular catalytic element to irreversibly expand against the inside surface of the substrate.

  9. Converting Transaldolase into Aldolase through Swapping of the Multifunctional Acid-Base Catalyst: Common and Divergent Catalytic Principles in F6P Aldolase and Transaldolase.

    PubMed

    Sautner, Viktor; Friedrich, Mascha Miriam; Lehwess-Litzmann, Anja; Tittmann, Kai

    2015-07-28

    Transaldolase (TAL) and fructose-6-phosphate aldolase (FSA) both belong to the class I aldolase family and share a high degree of structural similarity and sequence identity. The molecular basis of the different reaction specificities (transferase vs aldolase) has remained enigmatic. A notable difference between the active sites is the presence of either a TAL-specific Glu (Gln in FSA) or a FSA-specific Tyr (Phe in TAL). Both residues seem to have analoguous multifunctional catalytic roles but are positioned at different faces of the substrate locale. We have engineered a TAL double variant (Glu to Gln and Phe to Tyr) with an active site resembling that of FSA. This variant indeed exhibits aldolase activity as its main activity with a catalytic efficiency even larger than that of authentic FSA, while TAL activity is greatly impaired. Structural analysis of this variant in complex with the dihydroxyacetone Schiff base formed upon substrate cleavage identifies the introduced Tyr (genuine in FSA) to catalyze protonation of the central carbanion-enamine intermediate as a key determinant of the aldolase reaction. Our studies pinpoint that the Glu in TAL and the Tyr in FSA, although located at different positions at the active site, similarly act as bona fide acid-base catalysts in numerous catalytic steps, including substrate binding, dehydration of the carbinolamine, and substrate cleavage. We propose that the different spatial positions of the multifunctional Glu in TAL and of the corresponding multifunctional Tyr in FSA relative to the substrate locale are critically controlling reaction specificity through either unfavorable (TAL) or favorable (FSA) geometry of proton transfer onto the common carbanion-enamine intermediate. The presence of both potential acid-base residues, Glu and Tyr, in the active site of TAL has deleterious effects on substrate binding and cleavage, most likely resulting from a differently organized H-bonding network. Large-scale motions of the

  10. Biofuel production from catalytic thermochemical conversion of animal manure and biomass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of the research is to identify suitable catalysts to convert animal manure-based and biomass-based synthesis gas (syngas) to liquid biofuels such as mixed alcohols and hydrocarbons. Two pathways of catalytically converting syngas are investigated: (1)a two-step process involving the in...

  11. Catalytic process for manufacture of lubricating oils

    SciTech Connect

    Gorring, R.L.; La, P.R.

    1981-09-29

    A method is disclosed for converting an asphalt-free heavy hydrocarbon oil to high V.I. low pour point lube base stock and naphtha. The heavy oil is first catalytically dewaxed with a catalyst such as ni-zsm-5 and the dewaxed oil is then hydrocracked, or hydroconverted with a large pore zeolite catalyst such as dealuminized Y or zsm-20 associated with palladium. The V.I. is controlled by the severity of the hydroconversion step.

  12. Peptides present in the non-digestible fraction of common beans (Phaseolus vulgaris L.) inhibit the angiotensin-I converting enzyme by interacting with its catalytic cavity independent of their antioxidant capacity.

    PubMed

    Luna-Vital, Diego A; González de Mejía, Elvira; Mendoza, Sandra; Loarca-Piña, Guadalupe

    2015-05-01

    The aim was to evaluate the angiotensin-I converting enzyme (ACE) inhibitory potential and the antioxidant capacity of pure synthesized peptides (GLTSK, LSGNK, GEGSGA, MPACGSS and MTEEY) originally identified in the non-digestible fraction (NDF) of common beans (P. vulgaris L.) that had previously demonstrated antiproliferative activity against human colorectal cancer cells. The five peptides were able to inhibit ACE with half maximal inhibitory concentration (IC50) values ranging from 65.4 (GLTSK) to 191.5 μM (MPACGSS). The combination of GLTSK and MTEEY increased the ACE inhibition by 30% compared to equieffective doses of the single peptides. According to molecular docking analysis, the five peptides had lower estimated free energy values (-6.47 to -9.34 kcal mol(-1)) when they interacted with the catalytic site of ACE than that of the substrate hippuryl-histidyl-leucine (-5.41 kcal mol(-1)), thus inhibiting the enzymatic activity. According to molecular docking analysis, the five peptides interacted with four (His353, Ala354, Glu411 and Tyr523) out of 6 catalytic residues. Moreover, MPACGSS had the highest antioxidant activity according to Ferric reducing antioxidant power (FRAP) (421.58 μmol FeSO4 mg(-1)), Fe(2+) chelation (2.01 μmol Na2EDTA mg(-1)) assays, and also in DPPH (748.39 μmol Trolox per mg of dry peptide) and ABTS (561.42 μmol Trolox mg(-1)) radical scavenging assays. The results support the hypothesis that peptides present in the non-digestible fraction of common beans (Phaseolus vulgaris L.) may exert their physiological benefits independent of their antioxidant capacity, by ACE inhibition through interaction with its catalytic cavity. PMID:25881860

  13. Molecular catalytic coal liquid conversion

    SciTech Connect

    Stock, L.M.; Yang, Shiyong

    1995-12-31

    This research, which is relevant to the development of new catalytic systems for the improvement of the quality of coal liquids by the addition of dihydrogen, is divided into two tasks. Task 1 centers on the activation of dihydrogen by molecular basic reagents such as hydroxide ion to convert it into a reactive adduct (OH{center_dot}H{sub 2}){sup {minus}} that can reduce organic molecules. Such species should be robust withstanding severe conditions and chemical poisons. Task 2 is focused on an entirely different approach that exploits molecular catalysts, derived from organometallic compounds that are capable of reducing monocyclic aromatic compounds under very mild conditions. Accomplishments and conclusions are discussed.

  14. Nano sponge Mn₂O ₃ as a new adsorbent for the preconcentration of Pd(II) and Rh(III) ions in sea water, wastewater, rock, street sediment and catalytic converter samples prior to FAAS determinations.

    PubMed

    Yavuz, Emre; Tokalıoğlu, Serife; Sahan, Halil; Patat, Saban

    2014-10-01

    In this study, a nano sponge Mn2O3 adsorbent was synthesized and was used for the first time. Various parameters affecting the recovery values of Pd(II) and Rh(III) were examined. The tolerance limits (≥ 90 %) for both Pd(II) and Rh(III) ions were found to be 75,000 mg L(-1) Na(I), 75,000 mg L(-1) K(I), 50,000 mg L(-1) Mg(II) and 50,000 mg L(-1) Ca(II). A 30s contact time was enough for both adsorption and elution. A preconcentration factor of 100 was obtained by using 100mg of the nano sponge Mn2O3. The reusability of the adsorbent was 120 times. Adsorption capacities for Pd(II) and Rh(III) were found to be 42 and 6.2 mg g(-1), respectively. The detection limits were 1.0 µg L(-1) for Pd(II) and 0.37 µg L(-1) for Rh(III) and the relative standard deviations (RSD, %) were found to be ≤ 2.5%. The method was validated by analyzing the standard reference material, SRM 2556 (Used Auto Catalyst Pellets) and spiked real samples. The optimized method was applied for the preconcentration of Pd(II) and Rh(III) ions in water (sea water and wastewater), rock, street sediment and catalytic converter samples. PMID:25059126

  15. Interleaved power converter

    DOEpatents

    Zhu, Lizhi

    2007-11-13

    A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DC converters with three rather than four high voltage inverter legs.

  16. Porous media for catalytic renewable energy conversion

    NASA Astrophysics Data System (ADS)

    Hotz, Nico

    2012-05-01

    A novel flow-based method is presented to place catalytic nanoparticles into a reactor by sol-gelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.

  17. The curse of the CATalytic converter.

    PubMed

    James, E

    1997-01-01

    Addresses the transfer of nurse education from schools of nursing, previously located within health authorities and, more recently, hospital and/or community trusts, to institutions of higher education. The pressures this has produced for both providers and participants in this relatively new educational initiative have had a direct effect on the levels of stress and anxiety that students feel both in their initial professional qualification programmes and in continuing their personal and academic development subsequently. There is a paucity of research into this area of stress and student Angst as a result of the new educational thrust. Suggests that the evidence from student evaluations has not been collated adequately and that the result is a burgeoning of anecdotal evidence which is being ignored by nursing's professional body. Higher education has encouraged and influenced an almost exponential growth in programmes of study, which the nursing profession has used to force its singular aim to create a degree-based profession. PMID:10167879

  18. XTL Converter

    SciTech Connect

    Spurgeon, Steven R

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious; it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Header information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.

  19. XTL Converter

    Energy Science and Technology Software Center (ESTSC)

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious; it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Headermore » information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.« less

  20. Catalytic distillation structure

    DOEpatents

    Smith, Jr., Lawrence A.

    1984-01-01

    Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

  1. Catalytic reactor

    DOEpatents

    Aaron, Timothy Mark; Shah, Minish Mahendra; Jibb, Richard John

    2009-03-10

    A catalytic reactor is provided with one or more reaction zones each formed of set(s) of reaction tubes containing a catalyst to promote chemical reaction within a feed stream. The reaction tubes are of helical configuration and are arranged in a substantially coaxial relationship to form a coil-like structure. Heat exchangers and steam generators can be formed by similar tube arrangements. In such manner, the reaction zone(s) and hence, the reactor is compact and the pressure drop through components is minimized. The resultant compact form has improved heat transfer characteristics and is far easier to thermally insulate than prior art compact reactor designs. Various chemical reactions are contemplated within such coil-like structures such that as steam methane reforming followed by water-gas shift. The coil-like structures can be housed within annular chambers of a cylindrical housing that also provide flow paths for various heat exchange fluids to heat and cool components.

  2. Magnetorheological converters

    SciTech Connect

    Zal'tsgendler, E.A.; Kolomentsev, A.V.; Kordonskii, V.I.; Madorskii, L.S.

    1986-04-01

    The authors study the problems of constructing an electrohydraulic converter functioning based on the magnetoheological effect: the magnetorheological throttle (MR throttle). Requirements are listed that must be taken into account in developing the MR throttle. The paper attempts to calculate the flow-rate characteristics of the MR throttle. The rheological equation which describes sufficiently the mechanical properties of the magnetoheological suspensions is presented. The paper examines the calculation of the magnetic inductor for the example of a toroidal core with a gap, which simultaneously functions as the slot throttling channel. The use of the designs described enabled the development of bridge converters, which have a flat amplitude-frequency characteristic in the range 200-250 Hz and which have good energy indicators. Typical experimental logarithmic amplitude-frequency and phase-frequency characteristics of a bridge converter are shown.

  3. CURVES, VERTICES, KNOTS AND SUCH.

    ERIC Educational Resources Information Center

    FOLEY, JACK L.

    THIS BOOKLET, ONE OF A SERIES, HAS BEEN DEVELOPED FOR THE PROJECT, A PROGRAM FOR MATHEMATICALLY UNDERDEVELOPED PUPILS. A PROJECT TEAM, INCLUDING INSERVICE TEACHERS, IS BEING USED TO WRITE AND DEVELOP THE MATERIALS FOR THIS PROGRAM. THE MATERIALS DEVELOPED IN THIS BOOKLET INCLUDE SUCH CONCEPTS AS (1) SIMPLE CLOSED CURVES, (2) NETWORKS, (3) MAP…

  4. Asymmetric catalytic aziridination of cyclic enones.

    PubMed

    De Vincentiis, Francesco; Bencivenni, Giorgio; Pesciaioli, Fabio; Mazzanti, Andrea; Bartoli, Giuseppe; Galzerano, Patrizia; Melchiorre, Paolo

    2010-07-01

    The first catalytic method for the asymmetric aziridination of cyclic enones is described. The presented organocatalytic strategy is based on the use of an easily available organocatalyst that is able to convert a wide range of cyclic enones into the desired aziridines with very high enantiomeric purity and good chemical yield. Such a method may very well open up new opportunities to stereoselectively prepare complex chiral molecules that possess an indane moiety, a framework that is found in a large number of bioactive and pharmaceutically important molecules. PMID:20512797

  5. New cat converter design for compressors cuts service time

    SciTech Connect

    Not Available

    1993-04-19

    GPM Gas Corp., Houston, has begun replacing its catalytic converters on compressor engines with a converter that saves time and effort in inspection and maintenance, especially for converters that are elevated and difficult to access. The replacement is the Hatchbak converter designed and patented by Johnson Matthey Environmental Products Group, Wayne, PA. Its removable hatch, secured by only eight bolts, eliminates the need to remove the entire converter from the exhaust piping and thereby significantly cuts down time. Of approximately 285 engines at 75 booster stations and 4 gas processing sites, more than 40 are equipped with catalytic converters, many elevated as much as 20 ft. GPM has replaced more than half its previous catalytic converters atop the engines with the new design. The paper briefly describes the maintenance headaches and the new design.

  6. Catalytic fast pyrolysis of lignocellulosic biomass.

    PubMed

    Liu, Changjun; Wang, Huamin; Karim, Ayman M; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel-bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating value, high corrosiveness, high viscosity, and instability; they also greatly limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality. PMID:24801125

  7. Catalytic fast pyrolysis of lignocellulosic biomass

    SciTech Connect

    Liu, Changjun; Wang, Huamin; Karim, Ayman M.; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy Q3 carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel—bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating values, high corrosiveness, high viscosity, and instability; they also greatly Q4 limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

  8. Catalytic distillation structure

    DOEpatents

    Smith, L.A. Jr.

    1984-04-17

    Catalytic distillation structure is described for use in reaction distillation columns, and provides reaction sites and distillation structure consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and is present with the catalyst component in an amount such that the catalytic distillation structure consists of at least 10 volume % open space. 10 figs.

  9. Power converter

    NASA Technical Reports Server (NTRS)

    Black, J. M. (Inventor)

    1981-01-01

    A dc-to-dc converter employs four transistor switches in a bridge to chop dc power from a source, and a voltage multiplying diode rectifying ladder network to rectify and filter the chopped dc power for delivery to a load. The bridge switches are cross coupled in order for diagonally opposite pairs to turn on and off together using RC networks for the cross coupling to achieve the mode of operation of a free running multivibrator, and the diode rectifying ladder is configured to operate in a push-pull mode driven from opposite sides of the multivibrator outputs of the ridge switches. The four transistor switches provide a square-wave output voltage which as a peak-to-peak amplitude that is twice the input dc voltage, and is thus useful as a dc-to-ac inverter.

  10. Studies on exhaust emissions of catalytic coated spark ignition engine with adulterated gasoline.

    PubMed

    Muralikrishna, M V S; Kishor, K; Venkata Ramana Reddy, Ch

    2006-04-01

    Adulteration of automotive fuels, especially, gasoline with cheaper fuels is widespread throughout south Asia. Some adulterants decrease the performance and life of the engine and increase the emission of harmful pollutants causing environmental and health problems. The present investigation is carried out to study the exhaust emissions from a single cylinder spark ignition (SI) engine with kerosene blended gasoline with different versions of the engine, such as conventional engine and catalytic coated engine with different proportions of the kerosene ranging from 0% to 40% by volume in steps of 10% in the kerosene-gasoline blend. The catalytic coated engine used in the study has copper coating of thickness 400 microns on piston and inner surface of the cylinder head. The pollutants in the exhaust, carbon monoxide (CO) and unburnt hydrocarbons (UBHC) are measured with Netel Chromatograph CO and HC analyzer at peak load operation of the engine. The engine is provided with catalytic converter with sponge iron as a catalyst to control the pollutants from the exhaust of the engine. An air injection is also provided to the catalytic converter to further reduce the pollutants. The pollutants found to increase drastically with adulterated gasoline. Copper-coated engine with catalytic converter significantly reduced pollutants, when compared to conventional engine. PMID:17913184

  11. Nonuniversality of entanglement convertibility

    NASA Astrophysics Data System (ADS)

    Bragança, Helena; Mascarenhas, Eduardo; Luiz, G. I.; Duarte, C.; Pereira, R. G.; Santos, M. F.; Aguiar, M. C. O.

    2014-06-01

    Recently, it has been suggested that operational properties connected to quantum computation can be alternative indicators of quantum phase transitions. In this work we systematically study these operational properties in one-dimensional systems that present phase transitions of different orders. For this purpose, we evaluate the local convertibility between bipartite ground states. Our results suggest that the operational properties, related to nonanalyticities of the entanglement spectrum, are good detectors of explicit symmetries of the model, but not necessarily of phase transitions. We also show that thermodynamically equivalent phases, such as Luttinger liquids, may display different convertibility properties depending on the underlying microscopic model.

  12. Catalyst for converting synthesis gas to light olefins

    DOEpatents

    Rao, V. Udaya S.; Gormley, Robert J.

    1982-01-01

    A catalyst and process for making same useful in the catalytic hydrogenation of carbon monoxide in which a silicalite support substantially free of aluminum is soaked in an aqueous solution of iron and potassium salts wherein the iron and potassium are present in concentrations such that the dried silicalite has iron present in the range of from about 5 to about 25 percent by weight and has potassium present in an amount not less than about 0.2 percent by weight, and thereafter the silicalite is dried and combined with amorphous silica as a binder for pellets, the catalytic pellets are used to convert synthesis gas to C.sub.2 -C.sub.4 olefins.

  13. Convertible Stadium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Air flotation technology used in NASA's Apollo program has found an interesting application in Hawaii's Aloha Stadium near Honolulu. The stadium's configuration can be changed, by moving entire 7,000-seat sections on a cushion of air, for best accommodation of spectators and participants at different types of events. In most stadiums, only a few hundred seats can be moved, by rolling sections on wheels or rails. At Aloha Stadium, 28,000 of the 50,000 seats can be repositioned for better spectator viewing and, additionally, for improved playing conditions. For example, a stadium designed primarily for football may compromise the baseball diamond by providing only a shallow outfield. Aloha's convertibility allows a full-size baseball field as well as optimum configurations for many other types of sports and special events. The photos show examples. The stadium owes its versatility to air flotation technology developed by General Motors. Its first large-scale application was movement of huge segments of the mammoth Saturn V moonbooster during assembly operations at Marshall Space Flight Center.

  14. Thermionic converter

    DOEpatents

    Rasor, Ned S.; Britt, Edward J.

    1976-01-01

    A gas-filled thermionic converter is provided with a collector and an emitter having a main emitter region and an auxiliary emitter region in electrical contact with the main emitter region. The main emitter region is so positioned with respect to the collector that a main gap is formed therebetween and the auxiliary emitter region is so positioned with respect to the collector that an auxiliary gap is formed therebetween partially separated from the main gap with access allowed between the gaps to allow ionizable gas in each gap to migrate therebetween. With heat applied to the emitter the work function of the auxiliary emitter region is sufficiently greater than the work function of the collector so that an ignited discharge occurs in the auxiliary gap and the work function of the main emitter region is so related to the work function of the collector that an unignited discharge occurs in the main gap sustained by the ions generated in the auxiliary gap. A current flows through a load coupled across the emitter and collector due to the unignited discharge in the main gap.

  15. Self-powered microthermionic converter

    SciTech Connect

    Marshall, Albert C.; King, Donald B.; Zavadil, Kevin R.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-08-10

    A self-powered microthermionic converter having an internal thermal power source integrated into the microthermionic converter. These converters can have high energy-conversion efficiencies over a range of operating temperatures. Microengineering techniques are used to manufacture the converter. The utilization of an internal thermal power source increases potential for mobility and incorporation into small devices. High energy efficiency is obtained by utilization of micron-scale interelectrode gap spacing. Alpha-particle emitting radioisotopes can be used for the internal thermal power source, such as curium and polonium isotopes.

  16. Thyristor converter simulation and analysis

    SciTech Connect

    Zhang, S.Y.

    1991-01-01

    In this paper we present a simulation on thyristor converters. The simulation features nonlinearity, non-uniform firing, and the commutations. Several applications such as a current regulation, a converter frequency characteristics analysis, and a power line disturbance analysis will be presented. 4 refs., 4 figs.

  17. Plasma-assisted catalytic storage reduction system

    DOEpatents

    Penetrante, Bernardino M.; Vogtlin, George E.; Merritt, Bernard T.; Brusasco, Raymond M.

    2000-01-01

    A two-stage method for NO.sub.x reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons. The second stage employs a lean NO.sub.x trap to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage with a plasma, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons, such as propene. A flow of such hydrocarbons (C.sub.x H.sub.y) is input from usually a second pipe into at least a portion of the first chamber. The NO.sub.2 from the plasma treatment proceeds to a storage reduction catalyst (lean NO.sub.x trap) that converts NO.sub.2 to N.sub.2, CO.sub.2, and H.sub.2 O, and includes a nitrate-forming catalytic site. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the lean-NO.sub.x trap catalyst. The method allows for enhanced NO.sub.x reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

  18. Plasma-assisted catalytic storage reduction system

    DOEpatents

    Penetrante, Bernardino M.; Vogtlin, George E.; Merritt, Bernard T.; Brusasco, Raymond M.

    2002-01-01

    A two-stage method for NO.sub.x reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons. The second stage employs a lean NO.sub.x trap to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage with a plasma, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons, such as propene. A flow of such hydrocarbons (C.sub.x H.sub.y) is input from usually a second pipe into at least a portion of the first chamber. The NO.sub.2 from the plasma treatment proceeds to a storage reduction catalyst (lean NO.sub.x trap) that converts NO.sub.2 to N.sub.2, CO.sub.2, and H.sub.2 O, and includes a nitrate-forming catalytic site. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the lean-NO.sub.x trap catalyst. The method allows for enhanced NO.sub.x reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

  19. Catalytic coherence transformations

    NASA Astrophysics Data System (ADS)

    Bu, Kaifeng; Singh, Uttam; Wu, Junde

    2016-04-01

    Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and stochastic catalytic coherence transformations between a pair of pure quantum states. In particular, we show that the simultaneous decrease of a family of Rényi entropies of the diagonal parts of the states under consideration is a necessary and sufficient condition for the deterministic catalytic coherence transformations. Similarly, for stochastic catalytic coherence transformations we find the necessary and sufficient conditions for achieving a higher optimal probability of conversion. We thus completely characterize the coherence transformations among pure quantum states under incoherent operations. We give numerous examples to elaborate our results. We also explore the possibility of the same system acting as a catalyst for itself and find that indeed self-catalysis is possible. Further, for the cases where no catalytic coherence transformation is possible we provide entanglement-assisted coherence transformations and find the necessary and sufficient conditions for such transformations.

  20. Catalytic hydrotreating process

    DOEpatents

    Karr, Jr., Clarence; McCaskill, Kenneth B.

    1978-01-01

    Carbonaceous liquids boiling above about 300.degree. C such as tars, petroleum residuals, shale oils and coal-derived liquids are catalytically hydrotreated by introducing the carbonaceous liquid into a reaction zone at a temperature in the range of 300.degree. to 450.degree. C and a pressure in the range of 300 to 4000 psig for effecting contact between the carbonaceous liquid and a catalytic transition metal sulfide in the reaction zone as a layer on a hydrogen permeable transition metal substrate and then introducing hydrogen into the reaction zone by diffusing the hydrogen through the substrate to effect the hydrogenation of the carbonaceous liquid in the presence of the catalytic sulfide layer.

  1. Protective circuit for thyristor controlled systems and thyristor converter embodying such protective circuit

    DOEpatents

    Downhower, Jr., Francis H.; Finlayson, Paul T.

    1984-04-10

    A snubber circuit coupled across each thyristor to be gated in a chain of thyristors determines the critical output of a NOR LATCH whenever one snubber circuit could not be charged and discharged under normal gating conditions because of a short failure.

  2. Parametric energy converter

    SciTech Connect

    Johnson, R.N.

    1981-10-20

    A method and apparatus for converting thermal energy into mechanical energy by parametric pumping of rotary inertia. In a preferred embodiment, a modified tesla turbine rotor is positioned within a rotary boiler along its axis of rotation. An external heat source, such as solar radiation, is directed onto the outer casing of the boiler to convert the liquid to steam. As the steam spirals inwardly toward the discs of the rotor, the moment of inertia of the mass of steam is reduced to thereby substantially increase its kinetic energy. The laminar flow of steam between the discs of the rotor transfers the increased kinetic energy to the rotor which can be coupled out through an output shaft to perform mechanical work. A portion of the mechanical output can be fed back to maintain rotation of the boiler.

  3. Thermionic energy converters

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1983-01-01

    The efficiency of thermionic energy converters is improved by internal distribution of tiny sorted cesium diodes driven by the thermal gradient between the primary emitter and the collector. The tiny, sorted diode distribution comprises protrusions of the emitter material from the main emitter face which contact the main collector face thermally but not electrically. The main collector ends of the protrusions are separated from the main collector by a thin layer of insulation, such as aluminum oxide. The shorted tiny diode distribution augments cesium ionization through internal thermal effects only within the main diode. No electrical inputs are required. This ionization enhancement by the distribution of the tiny shorted diodes not only reduces the plasma voltage drop but also increases the power output and efficiency of the overall thermionic energy converter.

  4. Catalytic reaction in confined flow channel

    DOEpatents

    Van Hassel, Bart A.

    2016-03-29

    A chemical reactor comprises a flow channel, a source, and a destination. The flow channel is configured to house at least one catalytic reaction converting at least a portion of a first nanofluid entering the channel into a second nanofluid exiting the channel. The flow channel includes at least one turbulating flow channel element disposed axially along at least a portion of the flow channel. A plurality of catalytic nanoparticles is dispersed in the first nanofluid and configured to catalytically react the at least one first chemical reactant into the at least one second chemical reaction product in the flow channel.

  5. Reinforced corrugated thin metal foil strip useful in a catalytic converter core, a catalytic converter core containing said strip and an electrically heatable catalytic converter containing said core

    SciTech Connect

    Cornelison, R.C.; Whittenberger, W.A.

    1993-08-31

    A corrugated thin metal foil strip is described having a longitudinally extending center line with an initial strip width and having at least one longitudinal edge folded toward the center line of the strip prior to corrugating said strip to form a folded section and a remaining portion of the strip which is unfolded, the width of the folded section being from about 5% to about 25% of the width of the remaining portion of the strip which is unfolded.

  6. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

  7. Catalytic activities of platinum nanotubes: a density functional study

    NASA Astrophysics Data System (ADS)

    Mukherjee, Prajna; Gupta, Bikash C.; Jena, Puru

    2015-10-01

    In this work we investigate the catalytic properties of platinum nanotubes using density functional theory based calculations. In particular, we study the dissociation of hydrogen and oxygen molecules as well as oxidation of CO molecules. The results indicate that platinum nanotubes have good catalytic properties and can be effectively used in converting CO molecule to CO2.

  8. Catalytic Antioxidants and Neurodegeneration

    PubMed Central

    Golden, Tamara R.

    2009-01-01

    Abstract Oxidative stress, resulting from mitochondrial dysfunction, excitotoxicity, or neuroinflammation, is implicated in numerous neurodegenerative conditions. Damage due to superoxide, hydroxyl radical, and peroxynitrite has been observed in diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as in acute conditions that lead to neuronal death, such as stroke and epilepsy. Antioxidant therapies to remove these toxic compounds have been of great interest in treating these disorders. Catalytic antioxidants mimic the activities of superoxide dismutase or catalase or both, detoxifying superoxide and hydrogen peroxide, and in some cases, peroxynitrite and other toxic species as well. Several compounds have demonstrated efficacy in in vitro and in animal models of neurodegeneration, leading to optimism that catalytic antioxidants may prove to be useful therapies in human disease. Antioxid. Redox Signal. 11, 555–569. PMID:18754709

  9. Catalytic, hollow, refractory spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1987-01-01

    Improved, heterogeneous, refractory catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitable formed of a shell (12) of refractory such as alumina having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be itself catalytic or a catalytically active material coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  10. Catalytic thermal barrier coatings

    DOEpatents

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  11. Catalytic Membrane Sensors

    SciTech Connect

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  12. Electrothermodynamic (etd) power converter

    SciTech Connect

    Marks, A.M.

    1983-07-26

    These inventions relate to novel advances in Electrothermodynamics (ETD), also known as charged aerosol, heat/electric power generators: (1) A new more efficient, compact converging/diverging configuration comprising a torus of revolution (TORON) used with a gas flywheel. (2) A ''Method II'' two-fluid mixed flow ejector/converter in a gas flywheel loop employing a primary steam or a high molecular weight driver jet such as a fluorocarbon containing charged aerosol water droplets and a low molecular weight carrier gas such as hydrogen or helium with an electro-negative gas additive, in a Rankine cycle including a vapor/gas and liquid separator with a bypass to the ejector/converter loop. (3) A ''Method III'' two-fluid mixed flow comprising a supersonic jet expanding conically within a subsonic flow, separated by a boundary layer in which the charged aerosol forms downstream of the orifice, at a cross section of at least 100 times the orifice section; and in which the electric charge density of the charged aerosol decreases along the jet axis, whereby substantially all of the kinetic power of the jet is converted to electric power within the jet, there being no ejector. (4) An array of supersonic jets utilizing Method III. (5) An array of supersonic jets utilizing Method III without separating duct walls in which ''convection cells'' provide return flows, forming a plurality of TORON configurations. (6) A supercritical Rankline cycle in a single stage employing Method III. (7) A method IV two-fluid cycle uses charged aerosols in an inert gas and operates on an Ericsson-type cycle. (8) Optimum operating conditions are defined for Methods II, III, and IV. (9) A high potential emitter is employed with a grounded body, and a sapphire tube sealed to metal by a new technique provides an insulating duct for the high temperature, high pressure vapor.

  13. 40 CFR 1065.378 - NO2-to-NO converter conversion verification.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... catalytic activity of the NO2-to-NO converter has not deteriorated. (b) Measurement principles. An NO2-to-NO... 40 Protection of Environment 33 2014-07-01 2014-07-01 false NO2-to-NO converter conversion... Measurements § 1065.378 NO2-to-NO converter conversion verification. (a) Scope and frequency. If you use...

  14. 40 CFR 1065.378 - NO2-to-NO converter conversion verification.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... catalytic activity of the NO2-to-NO converter has not deteriorated. (b) Measurement principles. An NO2-to-NO... 40 Protection of Environment 33 2011-07-01 2011-07-01 false NO2-to-NO converter conversion... Measurements § 1065.378 NO2-to-NO converter conversion verification. (a) Scope and frequency. If you use...

  15. 40 CFR 1065.378 - NO2-to-NO converter conversion verification.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... catalytic activity of the NO2-to-NO converter has not deteriorated. (b) Measurement principles. An NO2-to-NO... 40 Protection of Environment 34 2013-07-01 2013-07-01 false NO2-to-NO converter conversion... Measurements § 1065.378 NO2-to-NO converter conversion verification. (a) Scope and frequency. If you use...

  16. 40 CFR 1065.378 - NO2-to-NO converter conversion verification.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... catalytic activity of the NO2-to-NO converter has not deteriorated. (b) Measurement principles. An NO2-to-NO... 40 Protection of Environment 34 2012-07-01 2012-07-01 false NO2-to-NO converter conversion... Measurements § 1065.378 NO2-to-NO converter conversion verification. (a) Scope and frequency. If you use...

  17. Catalytic extraction processing of contaminated scrap metal

    SciTech Connect

    Griffin, T.P.; Johnston, J.E.

    1994-12-31

    The contract was conceived to establish the commercial capability of Catalytic Extraction Processing (CEP) to treat contaminated scrap metal in the DOE inventory. In so doing, Molten Metal Technology, Inc. (MMT), pursued the following objectives: demonstration of the recycling of ferrous and non-ferrous metals--to establish that radioactively contaminated scrap metal can be converted to high-grade, ferrous and non-ferrous alloys which can be reused by DOE or reintroduced into commerce; immobilize radionuclides--that CEP will concentrate the radionuclides in a dense vitreous phase, minimize secondary waste generation and stabilize and reduce waste volume; destroy hazardous organics--that CEP will convert hazardous organics to valuable industrial gases, which can be used as feed gases for chemical synthesis or as an energy source; recovery volatile heavy metals--that CEP`s off-gas treatment system will capture volatile heavy metals, such as mercury and lead; and establish that CEP is economical for processing contaminated scrap metal in the DOE inventory--that CEP is a more cost-effective and, complete treatment and recycling technology than competing technologies for processing contaminated scrap. The process and its performance are described.

  18. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Gill, J. C.; Earle, R. V.; Mar, H. M.

    1982-01-01

    The objective of the Rotorcraft Convertible Engine Study was to define future research and technology effort required for commercial development by 1988 of convertible fan/shaft gas turbine engines for unconventional rotorcraft transports. Two rotorcraft and their respective missions were defined: a Fold Tilt Rotor aircraft and an Advancing Blade Concept (ABC) rotorcraft. Sensitivity studies were conducted with these rotorcraft to determine parametrically the influence of propulsion characteristics on aircraft size, mission fuel requirements, and direct operating costs (DOC). The two rotorcraft were flown with conventional propulsion systems (separate lift/cruise engines) and with convertible propulsion systems to determine the benefits to be derived from convertible engines. Trade-off studies were conducted to determine the optimum engine cycle and staging arrangement for a convertible engine. Advanced technology options applicable to convertible engines were studied. Research and technology programs were identified which would ensure technology readiness for commercial development of convertible engines by 1988.

  19. ITER convertible blanket evaluation

    SciTech Connect

    Wong, C.P.C.; Cheng, E.

    1995-09-01

    Proposed International Thermonuclear Experimental Reactor (ITER) convertible blankets were reviewed. Key design difficulties were identified. A new particle filter concept is introduced and key performance parameters estimated. Results show that this particle filter concept can satisfy all of the convertible blanket design requirements except the generic issue of Be blanket lifetime. If the convertible blanket is an acceptable approach for ITER operation, this particle filter option should be a strong candidate.

  20. The photoelectric displacement converter

    NASA Astrophysics Data System (ADS)

    Dragoner, Valeriu V.

    2005-02-01

    In the article are examined questions of constructing photoelectric displacement converter satisfying demands that are stated above. Converter has channels of approximate and precise readings. The approximate reading may be accomplished either by the method of reading from a code mask or by the method of the consecutive calculation of optical scale gaps number. Phase interpolator of mouar strips" gaps is determined as a precise measuring. It is shown mathematical model of converter that allow evaluating errors and operating speed of conversion.

  1. Heat flow in a pyroelectric converter

    NASA Astrophysics Data System (ADS)

    Olsen, R. B.; Butler, W. F.; Drummond, J. E.; Bruno, D. A.; Briscoe, J. M.

    1985-12-01

    A simulated pyroelectric converter has been constructed. The heat flow and temperature profiles within the converter have been measured. Computer simulations of the heat flow compare well with the measurements and predict an efficiency of 12 percent of the Carnot limit for a real pyroelectric converter with the operating configuration of the simulation. These heat flow results are useful in considerations of heat engines using active materials other than pyroelectrics, such as Nitinol, when these engines utilize similar heat flow management.

  2. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler, Lisle B.; Kokko, Edwin; Switzer, Vernon A

    2007-05-22

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  3. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler,; Lisle B.; Kokko, Edwin; Switzer, Vernon A

    2010-10-26

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  4. Catalytic pyrolysis using UZM-39 aluminosilicate zeolite

    SciTech Connect

    Nicholas, Christopher P; Boldingh, Edwin P

    2014-10-07

    A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and shown to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub.1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  5. Catalytic pyrolysis using UZM-39 aluminosilicate zeolite

    SciTech Connect

    Nicholas, Christpher P; Boldingh, Edwin P

    2013-12-17

    A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and show to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hyrdocarbons into hydrocarbons removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  6. Hypothesis-free? No such thing

    SciTech Connect

    Wiley, H. S.

    2008-06-01

    Finding meaningful relationships in complex datasets requires starting with the appropriate data. A hypothesis usually takes the form of a mechanistic relationship between a specific cause and a consequent effect, and this will almost always depend on experimental context. There are some circumstances when data must be gathered in the absence of context or hypothesis to characterize a system, but it is unrealistic to expect such preliminary studies to lead to significant biological insights. For this, you need a hypothesis. Systems biology might be the future of biology, but we still need hypotheses to take us where we want to go.

  7. There is no Such Thing as Attention

    PubMed Central

    Anderson, Britt

    2011-01-01

    Given that the core issues of attention research have been recognized for millenia, we do not know as much about attention as we should. I argue that the reasons for this failure are (1) we create spurious dichotomies, (2) we reify attention, treating it as a cause, when it is an effect, and (3) we equate a collection of facts with a theory. In order to correct these errors, we need a new technical vocabulary that allows for attentional effects to be continuously distributed, rather than merely present or absent, and that provides a basis for quantitative behavioral predictions that map onto neural substrates. The terminology of the Bayesian decision process has already proved useful for structuring conceptual discussions in other psychological domains, such as perception and decision making under uncertainty, and it had demonstrated early success in the domain of attention. By rejecting a reified, causal conception of attention, in favor of theories that produce attentional effects as consequences, psychologists will be able to conduct more definitive experiments. Such conceptual advances will then enhance the productivity of neuroscientists by allowing them to concentrate their data collection efforts on the richest soil. PMID:21977019

  8. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    DOEpatents

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-09-06

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  9. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    DOEpatents

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-03-08

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  10. Catalytic nanomotors: challenges and opportunities

    NASA Astrophysics Data System (ADS)

    Gibbs, John; Zhao, Yiping

    2011-06-01

    The fabrication of integrated nanomachinary systems can enable break-through applications in nanoelectronics, photonics, bioengineering, and drug delivery or disease treatment. Naturally occurring nanomotors are biological motor proteins powered by catalytic reactions, which convert the chemical energy from the environment into mechanical energy directly. It has been demonstrated recently that using a simple catalytic reaction and an asymmetric bimetallic nanorod, one can produce catalytic nanomotors that mimic the autonomous motions of bionanomotors. Yet the construction of artificial nanomachines remains a major contemporary challenge due to the lack of a flexible fabrication technique that can design the desired dynamic components. We use a design technique called dynamic shadowing growth that allows for the fabrication of a wide range of various geometries and the asymmetric placement of the catalyst is easily accomplished as well which is necessary for directed propulsion. Programming nanomotor behavior is possible through geometrically-focused design and by incorporating different materials into the nanomotor structure is a simple process as well. A propulsion mechanism based upon bubble ejection from the catalyst surface is introduced to explain the driving force, and the comparison of this driving mechanism with the self-electrophoresis mechanism is also studied. We have also successfully incorporated multiple parts to form complex nanomotor assemblies which exhibit motions not observed from individual parts by using magnetic interactions.

  11. Performance of Power Converters at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Elbuluk, Malik E.; Gerber, Scott; Hammoud, Ahmad; Patterson, Richard L.

    2001-01-01

    Power converters capable of operation at cryogenic temperatures are anticipated to play an important role in the power system architecture of future NASA deep space missions. Design of such converters to survive cryogenic temperatures will improve the power system performance and reduce development and launch costs. Aerospace power systems are mainly a DC distribution network. Therefore, DC/DC and DC/AC converters provide the outputs needed to different loads at various power levels. Recently, research efforts have been performed at the NASA Glenn Research Center (GRC) to design and evaluate DC/DC converters that are capable of operating at cryogenic temperatures. This paper presents a summary of the research performed to evaluate the low temperature performance of five DC/DC converters. Various parameters were investigated as a function of temperature in the range of 20 to -196 C. Data pertaining to the output voltage regulation and efficiency of the converters is presented and discussed.

  12. Photocapacitive image converter

    NASA Technical Reports Server (NTRS)

    Miller, W. E.; Sher, A.; Tsuo, Y. H. (Inventor)

    1982-01-01

    An apparatus for converting a radiant energy image into corresponding electrical signals including an image converter is described. The image converter includes a substrate of semiconductor material, an insulating layer on the front surface of the substrate, and an electrical contact on the back surface of the substrate. A first series of parallel transparent conductive stripes is on the insulating layer with a processing circuit connected to each of the conductive stripes for detecting the modulated voltages generated thereon. In a first embodiment of the invention, a modulated light stripe perpendicular to the conductive stripes scans the image converter. In a second embodiment a second insulating layer is deposited over the conductive stripes and a second series of parallel transparent conductive stripes perpendicular to the first series is on the second insulating layer. A different frequency current signal is applied to each of the second series of conductive stripes and a modulated image is applied to the image converter.

  13. Dignity: not such a useless concept.

    PubMed

    Killmister, Suzy

    2010-03-01

    In her 2003 article in the British Medical Journal, Ruth Macklin provocatively declared dignity to be a useless concept: either a vague restatement of other more precise values, such as autonomy or respect for persons, or an empty slogan. A recent response to Macklin has challenged this claim. Doris Schroeder attempts to rescue dignity by positing four distinct concepts that fall under the one umbrella term. She argues that much of the confusion surrounding dignity is due to the lack of disambiguation among these four concepts, but that once we understand the different values in question dignity becomes a powerful tool in the fields of human rights and bioethics. It is the goal of this paper to build upon Schroeder's insights by reconnecting the multiple strands of dignity she identifies. It will be argued that the usefulness of dignity as a guiding principle in medical ethics can be much improved by identifying the single conceptual link that ties together the various values flying under its banner. That conceptual link is provided by understanding dignity as the capacity to live by one's standards and principles. PMID:20211996

  14. Cascaded resonant bridge converters

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  15. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler, Lisle B.; Kokko, Edwin; Switzer, Vernon A.

    2011-03-15

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.

  16. Social Entrepreneurs and Catalytic Change.

    ERIC Educational Resources Information Center

    Waddock, Sandra A.; Post, James E.

    1991-01-01

    Social entrepreneurs are private citizens who play critical roles in bringing about catalytic changes in the public sector agenda and the perception of social issues. Factors that make their projects--such as the Partnership for a Drug-Free America and Earth Day--successful include problem complexity, credibility, and a commitment to a collective…

  17. Microminiature thermionic converters

    SciTech Connect

    King, Donald B.; Sadwick, Laurence P.; Wernsman, Bernard R.

    2001-09-25

    Microminiature thermionic converts (MTCs) having high energy-conversion efficiencies and variable operating temperatures. Methods of manufacturing those converters using semiconductor integrated circuit fabrication and micromachine manufacturing techniques are also disclosed. The MTCs of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. Existing prior art thermionic converter technology has energy conversion efficiencies ranging from 5-15%. The MTCs of the present invention have maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

  18. Fundamentals and Catalytic Applications of CeO2-Based Materials.

    PubMed

    Montini, Tiziano; Melchionna, Michele; Monai, Matteo; Fornasiero, Paolo

    2016-05-25

    Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40(th) anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are deepening our understanding of these materials, helping us to predict their behavior and application potential. This review has a wide view on all those aspects related to ceria which promise to produce an important impact on our life, encompassing fundamental knowledge of CeO2 and its properties, characterization toolbox, emerging features, theoretical studies, and all the catalytic applications, organized by their degree of establishment on the market. PMID:27120134

  19. Switchable catalytic DNA catenanes.

    PubMed

    Hu, Lianzhe; Lu, Chun-Hua; Willner, Itamar

    2015-03-11

    Two-ring interlocked DNA catenanes are synthesized and characterized. The supramolecular catenanes show switchable cyclic catalytic properties. In one system, the catenane structure is switched between a hemin/G-quadruplex catalytic structure and a catalytically inactive state. In the second catenane structure the catenane is switched between a catalytically active Mg(2+)-dependent DNAzyme-containing catenane and an inactive catenane state. In the third system, the interlocked catenane structure is switched between two distinct catalytic structures that include the Mg(2+)- and the Zn(2+)-dependent DNAzymes. PMID:25642796

  20. Olefin fractionation and catalytic conversion system

    SciTech Connect

    Owen, H.; Hsia, C.H.; Wright, B.S.

    1989-05-23

    A continuous catalytic system is described for converting a fraction of olefinic feedstock comprising ethylene and C/sub 3/+ olefins to heavier liquid hydrocarbon product comprising: (a) means for prefractionating the olefinic feedstock to obtain a gaseous stream rich in ethylene and a liquid stream containing C/sub 3/+ olefin; (b) means for vaporizing and contacting the liquid stream from the prefractionating step with hydrocarbon conversion oligomerization catalyst in a catalytic reactor system to provide a heavier hydrocarbon effluent stream comprising distillate, gasoline and lighter hydrocarbons; (c) means for fractionating the effluent stream to recover distillate, gasoline and lighter hydrocarbon separately; (d) means for recycling at least a portion of the recovered gasoline as a liquid sorption stream to prefractionating step (a); and (e) means for further reacting the recycled gasoline together with sorbed C/sub 3/+ olefin in the catalytic reactor system of step (b).

  1. Catalytic nanomotors: fabrication, mechanism, and applications

    NASA Astrophysics Data System (ADS)

    Gibbs, John; Zhao, Yiping

    2011-03-01

    Catalytic nanomotors are nano-to-micrometer-sized actuators that carry an on-board catalyst and convert local chemical fuel in solution into mechanical work. The location of this catalyst as well as the geometry of the structure dictate the swimming behaviors exhibited. The nanomotors can occur naturally in organic molecules, combine natural and artificial parts to form hybrid nanomotors or be purely artificial. Fabrication techniques consist of template directed electroplating, lithography, physical vapor deposition, and other advanced growth methods. Various physical and chemical propulsion mechanisms have been proposed to explain the motion behaviors including diffusiophoresis, bubble propulsion, interfacial tension gradients, and self-electrophoresis. The control and manipulation based upon external fields, catalytic alloys, and motion control through thermal modulation are discussed as well. Catalytic nanomotors represent an exciting technological challenge with the end goal being practical functional nanomachines that can perform a variety of tasks at the nanoscale.

  2. Catalytic hollow spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1986-01-01

    The improved, heterogeneous catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitably formed of a shell (12) of metal such as aluminum having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be, itself, catalytic or the catalyst can be coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  3. Catalytic hollow spheres

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1989-01-01

    The improved, heterogeneous catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitably formed of a shell (12) of metal such as aluminum having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be, itself, catalytic or the catalyst can be coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  4. Converting Nonclassicality into Entanglement.

    PubMed

    Killoran, N; Steinhoff, F E S; Plenio, M B

    2016-02-26

    Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are "symmetric coherent states," connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality. PMID:26967398

  5. Digital scale converter

    DOEpatents

    Upton, Richard G.

    1978-01-01

    A digital scale converter is provided for binary coded decimal (BCD) conversion. The converter may be programmed to convert a BCD value of a first scale to the equivalent value of a second scale according to a known ratio. The value to be converted is loaded into a first BCD counter and counted down to zero while a second BCD counter registers counts from zero or an offset value depending upon the conversion. Programmable rate multipliers are used to generate pulses at selected rates to the counters for the proper conversion ratio. The value present in the second counter at the time the first counter is counted to the zero count is the equivalent value of the second scale. This value may be read out and displayed on a conventional seven-segment digital display.

  6. Thermionic photovoltaic energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, D. L. (Inventor)

    1985-01-01

    A thermionic photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or gallium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

  7. Hydrogen peroxide catalytic decomposition

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2010-01-01

    Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated through the use of concentrated hydrogen peroxide fed as a monopropellant into a catalyzed thruster assembly. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50%-70% by volume, and may be increased in concentration in a continuous process preceding decomposition in the thruster assembly. The exhaust of the thruster assembly, rich in hydroxyl and/or hydroperoxy radicals, may be fed into a stream containing oxidizable components, such as nitric oxide, to facilitate their oxidation.

  8. Catalytic oxidation for treatment of ECLSS and PMMS waste streams. [Process Material Management Systems

    NASA Technical Reports Server (NTRS)

    Akse, James R.; Thompson, John; Scott, Bryan; Jolly, Clifford; Carter, Donald L.

    1992-01-01

    Catalytic oxidation was added to the baseline multifiltration technology for use on the Space Station Freedom in order to convert low-molecular weight organic waste components such as alcohols, aldehydes, ketones, amides, and thiocarbamides to CO2 at low temperature (121 C), thereby reducing the total organic carbon (TOC) to below 500 ppb. The rate of reaction for the catalytic oxidation of aqueous organics to CO2 and water depends primarily upon the catalyst, temperature, and concentration of reactants. This paper describes a kinetic study conducted to determine the impact of each of these parameters upon the reaction rate. The results indicate that a classic kinetic model, the Langmuir-Hinshelwood rate equation for heterogeneous catalysis, can accurately represent the functional dependencies of this rate.

  9. Method for recovering catalytic elements from fuel cell membrane electrode assemblies

    DOEpatents

    Shore, Lawrence; Matlin, Ramail; Heinz, Robert

    2012-06-26

    A method for recovering catalytic elements from a fuel cell membrane electrode assembly is provided. The method includes converting the membrane electrode assembly into a particulate material, wetting the particulate material, forming a slurry comprising the wetted particulate material and an acid leachate adapted to dissolve at least one of the catalytic elements into a soluble catalytic element salt, separating the slurry into a depleted particulate material and a supernatant containing the catalytic element salt, and washing the depleted particulate material to remove any catalytic element salt retained within pores in the depleted particulate material.

  10. Single-Pass Catalytic Conversion of Syngas into Olefins via Methanol.

    PubMed

    Olsbye, Unni

    2016-06-20

    All together now: Combination in a single reactor of the catalysts for converting syngas into methanol and methanol into olefins was recently reported by Cheng et al. This approach considerably simplifies the catalytic conversion of natural gas. PMID:27213983

  11. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Goldstein, D. N.; Hirschkron, R.; Smith, C. E.

    1983-01-01

    Convertible propulsion systems for advanced rotorcraft are evaluated in terms of their impact on aircraft operating economics and fuel consumption. A variety of propulsion system concepts, including separate thrust and power producing engines, convertible fan/shaft engines, and auxiliary propeller configurations are presented. The merits of each are evaluated in two different rotorcraft missions: an intercity, commercial transport of the ABC(TM) type, and an offshore oil ring supply ship of the X-wing type. The variable inlet guide vane fan/shaft converting engine and auxiliary propeller configurations are shown to offer significant advantages over all the other systems evaluated, in terms of both direct operating cost and fuel consumption.

  12. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  13. Vector generator scan converter

    DOEpatents

    Moore, James M.; Leighton, James F.

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  14. Two stage catalytic combustor

    NASA Technical Reports Server (NTRS)

    Alvin, Mary Anne (Inventor); Bachovchin, Dennis (Inventor); Smeltzer, Eugene E. (Inventor); Lippert, Thomas E. (Inventor); Bruck, Gerald J. (Inventor)

    2010-01-01

    A catalytic combustor (14) includes a first catalytic stage (30), a second catalytic stage (40), and an oxidation completion stage (49). The first catalytic stage receives an oxidizer (e.g., 20) and a fuel (26) and discharges a partially oxidized fuel/oxidizer mixture (36). The second catalytic stage receives the partially oxidized fuel/oxidizer mixture and further oxidizes the mixture. The second catalytic stage may include a passageway (47) for conducting a bypass portion (46) of the mixture past a catalyst (e.g., 41) disposed therein. The second catalytic stage may have an outlet temperature elevated sufficiently to complete oxidation of the mixture without using a separate ignition source. The oxidation completion stage is disposed downstream of the second catalytic stage and may recombine the bypass portion with a catalyst exposed portion (48) of the mixture and complete oxidation of the mixture. The second catalytic stage may also include a reticulated foam support (50), a honeycomb support, a tube support or a plate support.

  15. A solar thermophotovoltaic converter

    NASA Astrophysics Data System (ADS)

    Demichelis, F.; Minetti-Mezzetti, E.

    1980-08-01

    A model of a thermophotovoltaic (TPV) converter is presented. Sunlight was focused by an optical system into a spherical cavity made of tungsten or of ytterbium oxide, thereby heating the cavity. The spectral region of the incandescent radiation emitted by the cavity in the range 0.6-1.1 microns (corresponding to the maximum efficiency of silicon cells) was directed onto a distribution of cells facing the radiator. The part of the spectrum not in the range 0.6-1.1 microns was sent back to the radiator and recycled. Conversion efficiencies of about 24% are possible in a TPV converter operating with a 2000 K radiator.

  16. Catalytic conversion of light alkanes

    SciTech Connect

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  17. Fractional Watt AMTEC Converter

    NASA Astrophysics Data System (ADS)

    Hunt, T. K.; Rasmussen, J. R.

    2006-01-01

    We report here the long term performance of a small, multi-tube AMTEC converter. This converter was designed to operate and produce approximately 12 watt of electrical output from a small, 4 to 6 watt radioisotope heat source for remote power applications. It was built and put on test in 1999 using electrical heaters as stand-ins for the radioisotope capsule. Since that time it has accumulated more than 5 years of run time at an input heater temperature of 700 °C, with numerous thermal cycles to ambient that were generally related to grid power failures or physical moves of the test apparatus. The power output has remained, with variations due to orientation changes and minor variations due to small temperature changes, essentially constant at 0.40 W to 0.60 W over the test period and operation is ongoing. The converter casing and mechanical structure was fabricated from 316 SS and the electrodes are sputtered titanium nitride films. Separate static tests of a multilayer insulation package suitable for use with the converter showed the capability to reach 700 °C with a thermal input of < 4 watts.

  18. Thermionic energy converters

    DOEpatents

    Monroe, Jr., James E.

    1977-08-09

    A thermionic device for converting nuclear energy into electrical energy comprising a tubular anode spaced from and surrounding a cylindrical cathode, the cathode having an outer emitting surface of ruthenium, and nuclear fuel on the inner cylindrical surface. The nuclear fuel is a ceramic composition of fissionable material in a metal matrix. An axial void is provided to collect and contain fission product gases.

  19. Catalytic Products from a Bench-Scale, Simulated Fluidized-Bed Pyrolyzer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biomass (e.g. lignocellulosics and lipids) were catalytically converted under thermochemical conditions to bio-based, fungible industrial chemicals and products. The focus was on high temperature catalytic conversions of feedstocks in a bench-scale reactor designed to replicate a packed- or fluidiz...

  20. Catalytic conversion of lignocellulosic biomass to fine chemicals and fuels.

    PubMed

    Zhou, Chun-Hui; Xia, Xi; Lin, Chun-Xiang; Tong, Dong-Shen; Beltramini, Jorge

    2011-11-01

    Lignocellulosic biomass is the most abundant and bio-renewable resource with great potential for sustainable production of chemicals and fuels. This critical review provides insights into the state-of the-art accomplishments in the chemocatalytic technologies to generate fuels and value-added chemicals from lignocellulosic biomass, with an emphasis on its major component, cellulose. Catalytic hydrolysis, solvolysis, liquefaction, pyrolysis, gasification, hydrogenolysis and hydrogenation are the major processes presently studied. Regarding catalytic hydrolysis, the acid catalysts cover inorganic or organic acids and various solid acids such as sulfonated carbon, zeolites, heteropolyacids and oxides. Liquefaction and fast pyrolysis of cellulose are primarily conducted over catalysts with proper acidity/basicity. Gasification is typically conducted over supported noble metal catalysts. Reaction conditions, solvents and catalysts are the prime factors that affect the yield and composition of the target products. Most of processes yield a complex mixture, leading to problematic upgrading and separation. An emerging technique is to integrate hydrolysis, liquefaction or pyrolysis with hydrogenation over multifunctional solid catalysts to convert lignocellulosic biomass to value-added fine chemicals and bio-hydrocarbon fuels. And the promising catalysts might be supported transition metal catalysts and zeolite-related materials. There still exist technological barriers that need to be overcome (229 references). PMID:21863197

  1. Catalytic cracking process

    DOEpatents

    Lokhandwala, Kaaeid A.; Baker, Richard W.

    2001-01-01

    Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

  2. Liquid metal thermal electric converter

    DOEpatents

    Abbin, Joseph P.; Andraka, Charles E.; Lukens, Laurance L.; Moreno, James B.

    1989-01-01

    A liquid metal thermal electric converter which converts heat energy to electrical energy. The design of the liquid metal thermal electric converter incorporates a unique configuration which directs the metal fluid pressure to the outside of the tube which results in the structural loads in the tube to be compressive. A liquid metal thermal electric converter refluxing boiler with series connection of tubes and a multiple cell liquid metal thermal electric converter are also provided.

  3. Ex-Situ Catalytic Fast Pyrolysis Technology Pathway

    SciTech Connect

    Biddy, M.; Dutta, A.; Jones, S.; Meyer, A.

    2013-03-01

    This technology pathway case investigates converting woody biomass using ex-situ catalytic fast pyrolysis followed by upgrading to gasoline-, diesel-, and jet-range hydrocarbon blendstocks. Technical barriers and key research needs that should be pursued for this pathway to be competitive with petroleum-derived blendstocks have been identified.

  4. In-Situ Catalytic Fast Pyrolysis Technology Pathway

    SciTech Connect

    Biddy, M.; Dutta, A.; Jones, S.; Meyer, A.

    2013-03-01

    This technology pathway case investigates converting woody biomass using in-situ catalytic fast pyrolysis followed by upgrading to gasoline-, diesel-, and jet-range hydrocarbon blendstocks. Technical barriers and key research needs that should be pursued for this pathway to be competitive with petroleum-derived blendstocks have been identified.

  5. Digital to synchro converter

    NASA Technical Reports Server (NTRS)

    Predina, Joseph P. (Inventor)

    1989-01-01

    A digital-to-synchro converter is provided where a binary input code specifies a desired shaft angle and where an resolver type position transducer is employed with additional circuitry to generate a shaft position error signal indicative of the angular difference between the desired shaft angle and the actual shaft angle. The additional circuitry corrects for known and calculated errors in the shaft position detection process and equipment.

  6. Method for remotely powering a device such as a lunar rover

    NASA Technical Reports Server (NTRS)

    Deyoung, Russell J. (Inventor); Williams, Michael D. (Inventor); Walker, Gilbert H. (Inventor); Schuster, Gregory L. (Inventor); Lee, Ja H. (Inventor)

    1993-01-01

    A method of supplying power to a device such as a lunar rover located on a planetary surface is provided. At least one, and preferably three, laser satellites are set in orbit around the planet. Each satellite contains a nuclear reactor for generating electrical power. This electrical power is converted into a laser beam which is passed through an amplifying array and directed toward the device such as a lunar rover. The received laser beam is then converted into electrical power for use by the device.

  7. Catalytic Asymmetric Synthesis of Chiral Allylic Esters

    PubMed Central

    Cannon, Jeffrey S.; Kirsch, Stefan F.; Overman, Larry E.

    2010-01-01

    A broadly useful catalytic enantioselective synthesis of branched allylic esters from prochiral (Z)-2-alkene-1-ols has been developed. The starting allylic alcohol is converted to its trichloroacetimidate intermediate by reaction with trichloroacetonitrile, either in situ or in a separate step, and this intermediate undergoes clean enantioselective SN2′ substitution with a variety of carboxylic acids in the presence of the palladium(II) catalyst (Rp,S)-di-μ -acetatobis[(η5-2-(2'-(4'-methylethyl)oxazolinyl)cyclopentadienyl,1-C,3'-N)(η4-tetraphenylcyclobutadiene)cobalt]dipalladium, (Rp,S)-[COP-OAc]2 or its enantiomer. The scope and limitations of this useful catalytic asymmetric allylic esterification are defined. PMID:15740118

  8. Catalytic distillation process

    DOEpatents

    Smith, Jr., Lawrence A.

    1982-01-01

    A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  9. Catalytic distillation process

    DOEpatents

    Smith, L.A. Jr.

    1982-06-22

    A method is described for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C[sub 4] feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  10. Evolution of catalytic function

    NASA Technical Reports Server (NTRS)

    Joyce, G. F.

    1993-01-01

    An RNA-based evolution system was constructed in the laboratory and used to develop RNA enzymes with novel catalytic function. By controlling the nature of the catalytic task that the molecules must perform in order to survive, it is possible to direct the evolving population toward the expression of some desired catalytic behavior. More recently, this system has been coupled to an in vitro translation procedure, raising the possibility of evolving protein enzymes in the laboratory to produce novel proteins with desired catalytic properties. The aim of this line of research is to reduce darwinian evolution, the fundamental process of biology, to a laboratory procedure that can be made to operate in the service of organic synthesis.

  11. Transistorized converter provides nondissipative regulation

    NASA Technical Reports Server (NTRS)

    1964-01-01

    A transistorized regulator converter efficiently converts fluctuating input voltages to a constant output voltage, avoiding the use of saturable reactors. It is nondissipative in operation and functions in an open loop through variable duty cycles.

  12. Analysis of self-oscillating dc-to-dc converters

    NASA Technical Reports Server (NTRS)

    Burger, P.

    1974-01-01

    The basic operational characteristics of dc-to-dc converters are analyzed along with the basic physical characteristics of power converters. A simple class of dc-to-dc power converters are chosen which could satisfy any set of operating requirements, and three different controlling methods in this class are described in detail. Necessary conditions for the stability of these converters are measured through analog computer simulation whose curves are related to other operational characteristics, such as ripple and regulation. Further research is suggested for the solution of absolute stability and efficient physical design of this class of power converters.

  13. Cycloidal Wave Energy Converter

    SciTech Connect

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  14. Clean catalytic combustor program

    NASA Technical Reports Server (NTRS)

    Ekstedt, E. E.; Lyon, T. F.; Sabla, P. E.; Dodds, W. J.

    1983-01-01

    A combustor program was conducted to evolve and to identify the technology needed for, and to establish the credibility of, using combustors with catalytic reactors in modern high-pressure-ratio aircraft turbine engines. Two selected catalytic combustor concepts were designed, fabricated, and evaluated. The combustors were sized for use in the NASA/General Electric Energy Efficient Engine (E3). One of the combustor designs was a basic parallel-staged double-annular combustor. The second design was also a parallel-staged combustor but employed reverse flow cannular catalytic reactors. Subcomponent tests of fuel injection systems and of catalytic reactors for use in the combustion system were also conducted. Very low-level pollutant emissions and excellent combustor performance were achieved. However, it was obvious from these tests that extensive development of fuel/air preparation systems and considerable advancement in the steady-state operating temperature capability of catalytic reactor materials will be required prior to the consideration of catalytic combustion systems for use in high-pressure-ratio aircraft turbine engines.

  15. On lossless switched-capacitor power converters

    SciTech Connect

    Tse, C.K.; Wong, S.C.; Chow, M.H.L.

    1995-05-01

    This paper addresses the design of efficient switched-capacitor power converters. The discussion starts with a review of the fundamental limitation of switched-capacitor circuits which shows that the topology of such circuits and the ``forced`` step changes of capacitor voltages are the inherent attributes of power loss. Although the argument follows from a rather trivial result from basic circuit theory, it addresses an important issue on the maximum efficiency achievable in a switched-capacitor converter circuit. Based on the observed topological constraint of switched-capacitor converter circuits, the simplest lossless topology for AC/DC conversion is deduced. Also discussed is a simple version of lossless topology that achieves isolation between the source and the load. Finally, an experimental AC/DC switched-capacitor converter, based on the proposed idea, is presented which demonstrates an improved efficiency over other existing switched-capacitor converters. The proposed AC/DC converter contains no inductors and thus is suitable for custom IC implementation for very low power applications.

  16. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  17. Bidirectional buck boost converter

    DOEpatents

    Esser, Albert Andreas Maria

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

  18. Bidirectional buck boost converter

    DOEpatents

    Esser, A.A.M.

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero. 20 figs.

  19. Potential converter for laser-power beaming

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Williams, Michael D.; Schuster, Gregory L.; Iles, Peter A.

    1991-01-01

    Future space missions, such as those associated with the Space Exploration Initiative (SEI), will require large amounts of power for operation of bases, rovers, and orbit transfer vehicles. One method for supplying this power is to beam power from a spaced based or Earth based laser power station to a receiver where laser photons can be converted to electricity. Previous research has described such laser power stations orbiting the Moon and beaming power to a receiver on the surface of the Moon by using arrays of diode lasers. Photovoltaic converters that can be efficiently used with these diode lasers are described.

  20. Efficient polarization converter for projection displays.

    PubMed

    Yip, W C; Huang, H C; Kwok, H S

    1997-09-01

    In the waveguiding limit, a twisted nematic liquid crystal cell behaves as an achromatic polarization rotator. We propose and demonstrate the application of such a polarization rotator to convert unpolarized light into linearly polarized light with almost 100% efficiency. This polarization converter has a 2:1 aspect ratio, which is close to the 16:9 ratio for modern televisions. It can be used therefore in a projection display with polarization-dependent light valves such as a liquid crystal light valve. Both transmittive and reflective light valves can be used. The temperature dependence of the achromatic polarization rotator is also studied. PMID:18259503

  1. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  2. Fluorescent radiation converter

    NASA Technical Reports Server (NTRS)

    Viehmann, W. (Inventor)

    1981-01-01

    A fluorescence radiation converter is described which includes a substantially undoped optically transparent substrate and a waveshifter coating deposited on at least one portion of the substrate for absorption of radiation and conversion of fluorescent radiation. The coating is formed to substantially 1000 g/liter of a solvent, 70 to 200 g/liter of an organic polymer, and 0.2 to 25 g/liter of at least one organic fluorescent dye. The incoming incident radiation impinges on the coating. Radiation is absorbed by the fluorescent dye and is re-emitted as a longer wavelength radiation. Radiation is trapped within the substrate and is totally internally reflected by the boundary surface. Emitted radiation leaves the substrate ends to be detected.

  3. Unity power factor converter

    NASA Technical Reports Server (NTRS)

    Wester, Gene W. (Inventor)

    1980-01-01

    A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i.

  4. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J; Hryn, John N; Elam, Jeffrey W

    2013-08-27

    A nanoporous catalytic membrane which displays several unique features Including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity. Also provided is a method for producing a catalytic membrane having flow-through pores and discreet catalytic clusters adhering to the inside surfaces of the pores.

  5. Transient catalytic combustor model

    NASA Technical Reports Server (NTRS)

    Tien, J. S.

    1981-01-01

    A quasi-steady gas phase and thermally thin substrate model is used to analyze the transient behavior of catalytic monolith combustors in fuel lean operation. The combustor response delay is due to the substrate thermal inertia. Fast response is favored by thin substrate, short catalytic bed length, high combustor inlet and final temperatures, and small gas channel diameters. The calculated gas and substrate temperature time history at different axial positions provides an understanding of how the catalytic combustor responds to an upstream condition change. The computed results also suggest that the gas residence times in the catalytic bed in the after bed space are correlatable with the nondimensional combustor response time. The model also performs steady state combustion calculations; and the computed steady state emission characteristics show agreement with available experimental data in the range of parameters covered. A catalytic combustor design for automotive gas turbine engine which has reasonably fast response ( 1 second) and can satisfy the emission goals in an acceptable total combustor length is possible.

  6. Converting to proactive environmental management

    SciTech Connect

    Duff, P.B.

    1994-12-31

    There are three components which the environmental manager of any major company faces. The first component deals with complying with today`s laws and regulations. The second component involves correcting past disposal activities which were consistent with standard industrial practice and complied with the laws and regulations in effect at the time. In the 1990s, a third component has emerged and gained increasing importance: taking the environmental program beyond compliance. Improvements in areas such as waste minimization, toxic chemical usage reduction, product life-cycle design, and selection of off-site disposal facilities go beyond the current regulations to bring valuable environmental and economic benefits to the company and the community. The key to successfully managing an environmental organization is the ability to convert the company`s program from reactive to proactive. This chapter provides guidance on successfully making this conversion.

  7. Catalytic Organometallic Reactions of Ammonia

    PubMed Central

    Klinkenberg, Jessica L.

    2012-01-01

    Until recently, ammonia had rarely succumbed to catalytic transformations with homogeneous catalysts, and the development of such reactions that are selective for the formation of single products under mild conditions has encountered numerous challenges. However, recently developed catalysts have allowed several classes of reactions to create products with nitrogen-containing functional groups from ammonia. These reactions include hydroaminomethylation, reductive amination, alkylation, allylic substitution, hydroamination, and cross-coupling. This Minireview describes examples of these processes and the factors that control catalyst activity and selectivity. PMID:20857466

  8. Catalytic membranes beckon

    SciTech Connect

    Caruana, C.M.

    1994-11-01

    Chemical engineers here and abroad are finding that the marriage of catalysts and membranes holds promise for faster and more specific reactions, although commercialization of this technology is several years away. Catalytic membrane reactors (CMRs) combine a heterogeneous catalyst and a permselective membrane. Reactions performed by CMRs provide higher yields--sometimes as much as 50% higher--because of better reaction selectivity--as opposed to separation selectivity. CMRs also can work at very high temperatures, using ceramic materials that would not be possible with organic membranes. Although the use of CMRs is not widespread presently, the development of new membranes--particularly porous ceramic and zeolite membranes--will increase the potential to improve yields of many catalytic processes. The paper discusses ongoing studies, metal and advanced materials for membranes, the need for continued research, hydrogen recovery from coal-derived gases, catalytic oxidation of sulfides, CMRs for water purification, and oxidative coupling of methane.

  9. Catalytic processes in the atmospheres of Earth and venus.

    PubMed

    Demore, W B; Yung, Y L

    1982-09-24

    Photochemical processes in planetary atmospheres are strongly influenced by catalytic effects of minor constituents. Catalytic cycles in the atmospheres of Earth and Venus are closely related. For example, chlorine oxides (CIOx) act as catalysts in the two atmospheres. On Earth, they serve to convert odd oxygen (atomic oxygen and ozone) to molecular oxygen. On Venus they have a similar effect, but in addition they accelerate the reactions of atomic and molecular oxygen with carbon monoxide. The latter process occurs by a unique combination of CIOx catalysis and sulfur dioxide photosensitization. The mechanism provides an explanation for the very low extent of carbon dioxide decomposition by sunlight in the Venus atmosphere. PMID:17837628

  10. Optimum catalytic process for alcohol fuels from syngas

    SciTech Connect

    Not Available

    1990-04-28

    The objectives of this contract are to discover and evaluate the catalytic properties of novel homogeneous, heterogeneous, or combination catalytic systems for the production of alcohol fuel extenders from syngas, to evaluate analytically and on the bench scale novel reactor concepts for use in converting syngas to liquid fuel products, and to develop on the bench scale the best combination of chemistry, reactor, and total process configuration to achieve the minimum product cost for conversion of syngas to liquid fuel products. Methanol production and heterogeneous catalysis utilizing transition elements supported on metal oxides with spinel structure are discussed. 12 figs., 16 tabs.

  11. Hybrid switch for resonant power converters

    DOEpatents

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  12. Fuel densifier converts biomass into fuel cubes

    SciTech Connect

    Not Available

    1982-02-01

    A new cost-effective means to produce clean-burning and low cost commercial and industrial fuel is being introduced by Columbia Fuel Densification Corp., Phoenix. The Columbia Commercial Hydraulic Fuel Densifier converts raw biomass materials such as wood chips, paper, peat moss and rice hulls into densified fuel cubes. The densifier is mobile and its operation is briefly outlined.

  13. Steam reformer with catalytic combustor

    DOEpatents

    Voecks, Gerald E.

    1990-03-20

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  14. Steam reformer with catalytic combustor

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E. (Inventor)

    1990-01-01

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  15. Selective catalytic reduction of sulfur dioxide to elemental sulfur

    SciTech Connect

    Liu, Wei; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1992-01-01

    Elemental sulfur recovery from SO[sub 2]-containing gas streams is highly attractive as it produces a saleable. Product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox (reduction of SO[sub 2] with coke) and Claus plants(reaction of SO[sub 2] with H[sub 2]S over catalyst). This project win investigate a cerium oxide catalyst for the single-stage selective reduction SO[sub 2] to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified as a superior catalyst for SO[sub 2] reduction by CO to elemental sulfur because of its high activity and high selectivity to sulfur over COS over a wide temperature range(400--650C). Kinetic and parametric studies of SO[sub 2] reduction planned over various CeO[sub 2]-formulations will provide the necessary basis for development of a simplified process, a single-stage elemental sulfur recovery scheme from variable concentration gas streams. A first apparent application is treatment of regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought Claus-alternative'' for coal-fired power plant applications.

  16. Catalytic hydroprocessing of heavy oil feedstocks

    NASA Astrophysics Data System (ADS)

    Okunev, A. G.; Parkhomchuk, E. V.; Lysikov, A. I.; Parunin, P. D.; Semeikina, V. S.; Parmon, V. N.

    2015-09-01

    A grave problem of modern oil refining industry is continuous deterioration of the produced oil quality, on the one hand, and increase in the demand for motor fuels, on the other hand. This necessitates processing of heavy oil feedstock with high contents of sulfur, nitrogen and metals and the atmospheric residue. This feedstock is converted to light oil products via hydrogenation processes catalyzed by transition metal compounds, first of all, cobalt- or nickel-promoted molybdenum and tungsten compounds. The processing involves desulfurization, denitrogenation and demetallization reactions as well as reactions converting heavy hydrocarbons to lighter fuel components. The review discusses the mechanisms of reactions involved in the heavy feedstock hydroprocessing, the presumed structure and state of the catalytically active components and methods for the formation of supports with the desired texture. Practically used and prospective approaches to catalytic upgrading of heavy oil feedstock as well as examples of industrial processing of bitumen and vacuum residues in the presence of catalysts are briefly discussed. The bibliography includes 140 references.

  17. Electrodes For Alkali-Metal Thermoelectric Converters

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Wheeler, Bob L.; Jeffries-Nakamura, Barbara; Lamb, James L.; Bankston, C. Perry; Cole, Terry

    1989-01-01

    Combination of thin, porous electrode and overlying collector grid reduces internal resistance of alkali-metal thermoelectric converter cell. Low resistance of new electrode and grid boosts power density nearly to 1 W/cm2 of electrode area at typical operating temperatures of 1,000 to 1,300 K. Conductive grid encircles electrode film on alumina tube. Bus wire runs along tube to collect electrical current from grid. Such converters used to transform solar, nuclear, and waste heat into electric power.

  18. Combination solar photovoltaic heat engine energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  19. Engineering Metallic Nanoparticles for Enhancing and Probing Catalytic Reactions.

    PubMed

    Collins, Gillian; Holmes, Justin D

    2016-07-01

    Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications. The engineering of future heterogenous catalysts is also moving beyond size, shape and composition considerations. Advancements in understanding structure-property relationships have enabled incorporation of complex features such as tuning surface strain to influence the behavior of catalytic NPs. Exploiting plasmonic properties and altering colloidal surface chemistry through functionalization are also emerging as important areas for rational design of catalytic NPs. This news article will highlight the key developments and challenges to the future design of catalytic NPs. PMID:26823380

  20. Turbo-Brayton Power Converter

    NASA Technical Reports Server (NTRS)

    Breedlove, Jeffrey

    2015-01-01

    Future NASA space missions will require advanced thermal-to-electric power converters that are reliable, efficient, and lightweight. Creare, LLC, is developing a turbo-Brayton power converter that offers high efficiency and specific power. The converter employs gas bearings to provide maintenance free, long-life operation. Discrete components can be packaged to fit optimally with other subsystems, and the converter's continuous gas flow can communicate directly with remote heat sources and heat rejection surfaces without the need for ancillary heat-transfer components and intermediate flow loops. Creare has completed detailed analyses, trade studies, fabrication trials, and preliminary designs for the components and converter assembly. The company is fabricating and testing a breadboard converter.

  1. Isolated and soft-switched power converter

    DOEpatents

    Peng, Fang Zheng; Adams, Donald Joe

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  2. Pulsed thermionic converter study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasmadynamic accelerator (MPD arc jet) is described, and the results of preliminary analyses are presented. In this system, the MPD thruster operates intermittently at higher voltages and power levels than the thermionic generating unit. A typical thrust pulse from the MPD arc jet is characterized by power levels of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. The thermionic generating unit operates continuously but with a lower power level of approximately 0.4 MWe. Energy storage between thrust pulses is provided by building up a large current in an inductor using the output of the thermionic converter array. Periodically, the charging current is interrupted, and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. The results of the preliminary analysis show that a coupling effectiveness of approximately 85 to 90% is feasible for a nominal 400 KWe system with an inductive unit suitable for a flight vehicle.

  3. Hollow fiber catalytic membranes

    SciTech Connect

    Ma, Yi Hua; Moser, W.; Shelekhin, A.; Pien, Shyhing

    1993-09-01

    The objective of the present research is to investigate the possibility of the enhancement of the H{sub 2}S thermal decomposition in the IGCC system by employing the hollow fiber catalytic membrane reactor. To accomplish the objective, the following major components in the analysis of the high temperature membrane reactor must be investigated: high-temperature stability of the porous glass membrane; catalytic properties of MoS{sub 2} and of the porous glass membrane; catalytic decomposition of H{sub 2}S in a packed bed reactor; catalytic decomposition of 100%, 8.6%, and 1.1% H{sub 2}S gas mixtures in the membrane reactor. The study has been shown that the conversion of the H{sub 2}S can be increased in the packed bed membrane reactor compared to the equilibrium conversion on the shell side. The development of a mathematical model for the proposed process is in progress. The model will enable optimization of the H{sub 2}S decomposition. These conditions include selectivity factors and pressure drop across the membrane.

  4. Monolithic catalytic igniters

    NASA Technical Reports Server (NTRS)

    La Ferla, R.; Tuffias, R. H.; Jang, Q.

    1993-01-01

    Catalytic igniters offer the potential for excellent reliability and simplicity for use with the diergolic bipropellant oxygen/hydrogen as well as with the monopropellant hydrazine. State-of-the-art catalyst beds - noble metal/granular pellet carriers - currently used in hydrazine engines are limited by carrier stability, which limits the hot-fire temperature, and by poor thermal response due to the large thermal mass. Moreover, questions remain with regard to longevity and reliability of these catalysts. In this work, Ultramet investigated the feasibility of fabricating monolithic catalyst beds that overcome the limitations of current catalytic igniters via a combination of chemical vapor deposition (CVD) iridium coatings and chemical vapor infiltration (CVI) refractory ceramic foams. It was found that under all flow conditions and O2:H2 mass ratios tested, a high surface area monolithic bed outperformed a Shell 405 bed. Additionally, it was found that monolithic catalytic igniters, specifically porous ceramic foams fabricated by CVD/CVI processing, can be fabricated whose catalytic performance is better than Shell 405 and with significantly lower flow restriction, from materials that can operate at 2000 C or higher.

  5. Catalytic coal liquefaction process

    DOEpatents

    Garg, D.; Sunder, S.

    1986-12-02

    An improved process for catalytic solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a solvent comprises using as catalyst a mixture of a 1,2- or 1,4-quinone and an alkaline compound, selected from ammonium, alkali metal, and alkaline earth metal oxides, hydroxides or salts of weak acids. 1 fig.

  6. Catalytic coal liquefaction process

    DOEpatents

    Garg, Diwakar; Sunder, Swaminathan

    1986-01-01

    An improved process for catalytic solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a solvent comprises using as catalyst a mixture of a 1,2- or 1,4-quinone and an alkaline compound, selected from ammonium, alkali metal, and alkaline earth metal oxides, hydroxides or salts of weak acids.

  7. Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System

    PubMed Central

    Buonomo, Joseph A; Aldrich, Courtney C

    2015-01-01

    The Mitsunobu reaction is renowned for its mild reaction conditions and broad substrate tolerance, but has limited utility in process chemistry and industrial applications due to poor atom economy and the generation of stoichiometric phosphine oxide and hydrazine by-products that complicate purification. A catalytic Mitsunobu reaction using innocuous reagents to recycle these by-products would overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1-phenylphospholane) employing phenylsilane to recycle the catalyst. Integration of this phosphine catalytic cycle with Taniguchi’s azocarboxylate catalytic system provided the first fully catalytic Mitsunobu reaction. PMID:26347115

  8. Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System.

    PubMed

    Buonomo, Joseph A; Aldrich, Courtney C

    2015-10-26

    The Mitsunobu reaction is renowned for its mild reaction conditions and broad substrate tolerance, but has limited utility in process chemistry and industrial applications due to poor atom economy and the generation of stoichiometric phosphine oxide and hydrazine by-products that complicate purification. A catalytic Mitsunobu reaction using innocuous reagents to recycle these by-products would overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1-phenylphospholane) employing phenylsilane to recycle the catalyst. Integration of this phosphine catalytic cycle with Taniguchi's azocarboxylate catalytic system provided the first fully catalytic Mitsunobu reaction. PMID:26347115

  9. Effect of dry torrefaction on kinetics of catalytic pyrolysis of sugarcane bagasse

    NASA Astrophysics Data System (ADS)

    Daniyanto, Sutijan, Deendarlianto, Budiman, Arief

    2015-12-01

    Decreasing world reserve of fossil resources (i.e. petroleum oil, coal and natural gas) encourage discovery of renewable resources as subtitute for fossil resources. Biomass is one of the main natural renewable resources which is promising resource as alternate resources to meet the world's energy needs and raw material to produce chemical platform. Conversion of biomass, as source of energy, fuel and biochemical, is conducted using thermochemical process such as pyrolysis-gasification process. Pyrolysis step is an important step in the mechanism of pyrolysis - gasification of biomass. The objective of this study is to obtain the kinetic reaction of catalytic pyrolysis of dry torrified sugarcane bagasse which used Ca and Mg as catalysts. The model of kinetic reaction is interpreted using model n-order of single reaction equation of biomass. Rate of catalytic pyrolysis reaction depends on the weight of converted biomass into char and volatile matters. Based on TG/DTA analysis, rate of pyrolysis reaction is influenced by the composition of biomass (i.e. hemicellulose, cellulose and lignin) and inorganic component especially alkali and alkaline earth metallic (AAEM). From this study, it has found two equations rate of reaction of catalytic pyrolysis in sugarcane bagasse using catalysts Ca and Mg. First equation is equation of pyrolysis reaction in rapid zone of decomposition and the second equation is slow zone of decomposition. Value of order reaction for rapid decomposition is n > 1 and for slow decomposition is n<1. Constant and order of reactions for catalytic pyrolysis of dry-torrified sugarcane bagasse with presence of Ca tend to higher than that's of presence of Mg.

  10. New Catalytic DNA Biosensors for Radionuclides and Metal ion

    SciTech Connect

    Yi Lu

    2008-03-01

    We aim to develop new DNA biosensors for simultaneous detection and quantification of bioavailable radionuclides, such as uranium, technetium, and plutonium, and metal contaminants, such as lead, chromium, and mercury. The sensors will be highly sensitive and selective. They will be applied to on-site, real-time assessment of concentration, speciation, and stability of the individual contaminants before and during bioremediation, and for long-term monitoring of DOE contaminated sites. To achieve this goal, we have employed a combinatorial method called “in vitro selection” to search from a large DNA library (~ 1015 different molecules) for catalytic DNA molecules that are highly specific for radionuclides or other metal ions through intricate 3-dimensional interactions as in metalloproteins. Comprehensive biochemical and biophysical studies have been performed on the selected DNA molecules. The findings from these studies have helped to elucidate fundamental principles for designing effective sensors for radionuclides and metal ions. Based on the study, the DNA have been converted to fluorescent or colorimetric sensors by attaching to it fluorescent donor/acceptor pairs or gold nanoparticles, with 11 part-per-trillion detection limit (for uranium) and over million fold selectivity (over other radionuclides and metal ions tested). Practical application of the biosensors for samples from the Environmental Remediation Sciences Program (ERSP) Field Research Center (FRC) at Oak Ridge has also been demonstrated.

  11. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  12. Catalytic desulfurization of industrial waste gases

    SciTech Connect

    Dupin, Th.

    1985-07-30

    Industrial waste gases containing objectionable/polluting compounds of sulfur, e.g., H/sub 2/S, SO/sub 2/ and such organosulfur derivatives as COS, CS/sub 2/ and mercaptans, are catalytically desulfurized, e.g., by Claus process, employing an improved catalyst comprising titanium dioxide and calcium, barium, strontium or magnesium sulfate.

  13. Catalytic Combustor for Fuel-Flexible Turbine

    SciTech Connect

    W. R. Laster; E. Anoshkina

    2008-01-31

    Under the sponsorship of the U. S. Department of Energy's National Energy Technology Laboratory, Siemens Westinghouse has conducted a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1 - Implementation Plan, Phase 2 - Validation Testing and Phase 3 - Field Testing. Both Phase 1 and Phase 2 of the program have been completed. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCLTM) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to oxidize a portion of the fuel, increasing the temperature of fuel/air mixture prior to the main combustion zone. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the technology necessary for the application of the catalytic concept to IGCC fuels was developed through detailed design and subscale testing. Phase III (currently not funded) will consist of full-scale combustor basket testing on natural gas and syngas.

  14. Catalytic Combustor for Fuel-Flexible Turbine

    SciTech Connect

    Laster, W. R.; Anoshkina, E.

    2008-01-31

    Under the sponsorship of the U. S. Department of Energy’s National Energy Technology Laboratory, Siemens Westinghouse has conducted a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1- Implementation Plan, Phase 2- Validation Testing and Phase 3 – Field Testing. Both Phase 1 and Phase 2 of the program have been completed. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCLTM) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to oxidize a portion of the fuel, increasing the temperature of fuel/air mixture prior to the main combustion zone. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the technology necessary for the application of the catalytic concept to IGCC fuels was developed through detailed design and subscale testing. Phase III (currently not funded) will consist of full-scale combustor basket testing on natural gas and syngas.

  15. Catalytic Combustor for Fuel-Flexible Turbine

    SciTech Connect

    W. R. Laster; E. Anoshkina; P. Szedlacsek

    2006-03-31

    Under the sponsorship of the U.S. Department of Energy's National Energy Technology Laboratory, Siemens Westinghouse is conducting a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1-Implementation Plan, Phase 2-Validation Testing and Phase 3-Field Testing. The Phase 1 program has been completed. Phase II was initiated in October 2004. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCL{trademark}) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to react part of the fuel, increasing the fuel/air mixture temperature. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the catalytic concept will be demonstrated through subscale testing. Phase III will consist of full-scale combustor basket testing on natural gas and syngas.

  16. Asymmetric catalytic transformations in supercritical carbon dioxide

    SciTech Connect

    Feng, Shaoguang; Tumas, W.; Gross, M.F.; Burk, M.J.

    1996-12-31

    Supercritical carbon dioxide can be a useful environmentally benign solvent for a wide range of catalytic reactions. We have been exploring the utility of supercritical carbon dioxide as a reaction medium for catalytic asymmetric transformations. We will present results on the asymmetric hydrogenation of prochiral olefins, ketones, and unsaturated acids by Rh and Ru catalysts containing chiral phosphine ligands using hydrogen or hydrogen transfer agents. We have found that asymmetric catalytic hydrogenation reactions of enamide esters work as well or better in CO{sub 2} than in conventional solvents. We have been able to effect high conversions and ee`s using hydrogen transfer systems such as HCOOH/NEt{sub 3}, We will discuss temperature, pressure and solvent density effects on selectivity and reactivity. Kinetic studies will also be presented in order to understand the enhanced enantioselectivity that we observed in SC CO{sub 2}.

  17. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 7 2011-04-01 2009-04-01 true Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  18. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 7 2010-04-01 2010-04-01 true Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  19. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 7 2013-04-01 2013-04-01 false Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  20. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 7 2012-04-01 2012-04-01 false Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  1. Catalytic upgrading of butyric acid towards fine chemicals and biofuels

    PubMed Central

    Sjöblom, Magnus; Matsakas, Leonidas; Christakopoulos, Paul; Rova, Ulrika

    2016-01-01

    Fermentation-based production of butyric acid is robust and efficient. Modern catalytic technologies make it possible to convert butyric acid to important fine chemicals and biofuels. Here, current chemocatalytic and biocatalytic conversion methods are reviewed with a focus on upgrading butyric acid to 1-butanol or butyl-butyrate. Supported Ruthenium- and Platinum-based catalyst and lipase exhibit important activities which can pave the way for more sustainable process concepts for the production of green fuels and chemicals. PMID:26994015

  2. A critical view on catalytic pyrolysis of biomass.

    PubMed

    Venderbosch, R H

    2015-04-24

    The rapid heating of biomass in an oxygen-free environment optimizes the yield of fast-pyrolysis liquids. This liquid comprises a mix of acids, (dehydrated) carbohydrates, aldehydes, ketones, lignin fragments, aromatics, and alcohols, limiting its use. Deoxygenation of these liquids to replace hydrocarbons represents significant challenges. Catalytic pyrolysis is seen as a promising route to yield liquids with a higher quality. In this paper, literature data on catalytic fast pyrolysis of biomass are reviewed and deoxygenation results correlated with the overall carbon yield. Evidence is given that in an initial stage of the catalytic process reactive components are converted to coke, gas, and water, and only to a limited extent to a liquid product. Catalysts are not yet good enough, and an appropriate combination of pyrolysis conditions, reactive products formed, and different reactions to take place to yield improved quality liquids may be practically impossible. PMID:25872757

  3. Dual Nanoparticle/Substrate Control of Catalytic Dehydrogenation

    SciTech Connect

    Borisevich, Albina Y; Wang, Sanwu; Rashkeev, Sergey; Glazoff, Michael V; Pennycook, Stephen J; Pantelides, Sokrates T

    2007-01-01

    Saturated hydrocarbons, or alkanes (C{sub n}H{sub 2n+2}), are abundant in petroleum and can be converted to alkenes (C{sub n}H{sub 2n}) by dehydrogenation. Alkenes, also known as unsaturated hydrocarbons, are easy to polymerize and are the primary feedstock of the petrochemical industry, especially ethene (n=2) and propene (n = 3). Efficient catalytic dehydrogenation is therefore a major industrial objective. It has been found that oxidative catalytic dehydrogenation, that is, a process assisted by both a solid catalyst and a flow of oxygen gas, is most practical because of higher system longevity. Chromia/alumina catalytic systems have been widely adopted by industry. They have also been the subject of scientific studies seeking understanding that may help optimization of the process.

  4. Advanced byproduct recovery: Direct catalytic reduction of sulfur dioxide to elemental sulfur. Fourth quarterly technical progress report

    SciTech Connect

    1997-01-01

    The team of Arthur D. Little, Tufts University and Engelhard Corporation are conducting Phase 1 of a four and a half year, two-phase effort to develop and scale-up an advanced byproduct recovery technology that is a direct, single-stage, catalytic process for converting sulfur dioxide to elemental sulfur. This catalytic process reduces SO{sub 2} over a fluorite-type oxide (such as ceria and zirconia). The catalytic activity can be significantly promoted by active transition metals, such as copper. More than 95% elemental sulfur yield, corresponding to almost complete sulfur dioxide conversion, was obtained over a Cu-Ce-O oxide catalyst as part of an on-going DOE-sponsored, University Coal Research Program. This type of mixed metal oxide catalyst has stable activity, high selectivity for sulfur production, and is resistant to water and carbon dioxide poisoning. Tests with CO and CH{sub 4} reducing gases indicate that the catalyst has the potential for flexibility with regard to the composition of the reducing gas, making it attractive for utility use. The performance of the catalyst is consistently good over a range of SO{sub 2} inlet concentration (0.1 to 10%) indicating its flexibility in treating SO{sub 2} tail gases as well as high concentration streams.

  5. Catalytic properties of single layers of transition metal sulfide catalytic materials

    SciTech Connect

    Chianelli, R.R.; Siadati, M.H.; De la Rosa, M.P.; Berhault, G.; Wilcoxon, J.P.; Bearden, R.; Abrams, B.L.

    2006-01-15

    Single layer transition metal sulfides (SLTMS) such as MoS{sub 2}, WS{sub 2}, and ReS{sub 2}, play an important role in catalytic processes such as the hydrofining of petroleum streams, and are involved in at least two of the slurry-catalyst hydroconversion processes that have been proposed for upgrading heavy petroleum feed and other sources of hydrocarbon fuels such as coal and shale oils. Additional promising catalytic applications of the SLTMS are on the horizon. The physical, chemical, and catalytic properties of these materials are reviewed in this report. Also discussed are areas for future research that promise to lead to advanced applications of the SLTMS.

  6. Catalytic reforming catalyst

    SciTech Connect

    Buss, W.C.; Kluksdahl, H.E.

    1980-12-09

    An improved catalyst, having a reduced fouling rate when used in a catalytic reforming process, said catalyst comprising platinum disposed on an alumina support wherein the alumina support is obtained by removing water from aluminum hydroxide produced as a by-product from a ziegler higher alcohol synthesis reaction, and wherein the alumina is calcined at a temperature of 1100-1400/sup 0/F so as to have a surface area of 165 to 215 square meters per gram.

  7. Catalytic combustion nears application

    SciTech Connect

    1994-11-01

    This article is a brief review of efforts to develope a catalytic combustion system with emissions levels less than 10 ppm. Two efforts are discussed: (1) tests by General Electric using a GE Frame 7E/9E and 7F/9F gas turbine, and (2) tests by AES using a Kawasaki M1A-13A industrial gas turbine. The latter also employs a heat recovery steam generator and produces 3 MWe and 28,000 lbm/hr of steam.

  8. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J.; Hryn, John N.; Elam, Jeffrey W.

    2009-12-01

    A nanoporous catalytic membrane which displays several unique features including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity.

  9. Multilevel converters for large electric drives

    SciTech Connect

    Tolbert, L.M.; Peng, F.Z.

    1997-11-01

    Traditional two-level high frequency pulse width modulation (PWM) inverters for motor drives have several problems associated with their high frequency switching which produces common-mode voltage and high voltage change (dV/dt) rates to the motor windings. Multilevel inverters solve these problems because their devices can switch at a much lower frequency. Two different multilevel topologies are identified for use as a converter for electric drives, a cascade inverter with separate dc sources and a back-to-back diode clamped converter. The cascade inverter is a natural fit for large automotive all electric drives because of the high VA ratings possible and because it uses several levels of dc voltage sources which would be available from batteries or fuel cells. The back to back diode damped converter is ideal where a source of ac voltage is available such as a hybrid electric vehicle. Simulation and experimental results show the superiority of these two converters over PWM based drives.

  10. STIFF: Converting Scientific FITS Images to TIFF

    NASA Astrophysics Data System (ADS)

    Bertin, Emmanuel

    2011-10-01

    STIFF is a program that converts scientific FITS1 images to the more popular TIFF2 format for illustration purposes. Most FITS readers and converters do not do a proper job at converting FITS image data to 8 bits. 8-bit images stored in JPEG, PNG or TIFF files have the intensities implicitely stored in a non-linear way. Most current FITS image viewers and converters provide the user an incorrect translation of the FITS image content by simply rescaling linearly input pixel values. A first consequence is that the people working on astronomical images usually have to apply narrow intensity cuts or square-root or logarithmic intensity transformations to actually see something on their deep-sky images. A less obvious consequence is that colors obtained by combining images processed this way are not consistent across such a large range of surface brightnesses. Though with other software the user is generally afforded a choice of nonlinear transformations to apply in order to make the faint stuff stand out more clearly in the images, with the limited selection of choices provides, colors will not be accurately rendered, and some manual tweaking will be necessary. The purpose of STIFF is to produce beautiful pictures in an automatic and consistent way.

  11. Processes for converting lignocellulosics to reduced acid pyrolysis oil

    SciTech Connect

    Kocal, Joseph Anthony; Brandvold, Timothy A

    2015-01-06

    Processes for producing reduced acid lignocellulosic-derived pyrolysis oil are provided. In a process, lignocellulosic material is fed to a heating zone. A basic solid catalyst is delivered to the heating zone. The lignocellulosic material is pyrolyzed in the presence of the basic solid catalyst in the heating zone to create pyrolysis gases. The oxygen in the pyrolysis gases is catalytically converted to separable species in the heating zone. The pyrolysis gases are removed from the heating zone and are liquefied to form the reduced acid lignocellulosic-derived pyrolysis oil.

  12. Wind/water energy converter

    NASA Technical Reports Server (NTRS)

    Paulkovich, J.

    1979-01-01

    Device will convert wind, water, tidal or wave energy into electrical or mechanical energy. Is comprised of windmill-like paddles or blades synchronously geared to orient themselves to wind direction for optimum energy extraction.

  13. Boron nitride converted carbon fiber

    DOEpatents

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  14. Superconducting active impedance converter

    DOEpatents

    Ginley, D.S.; Hietala, V.M.; Martens, J.S.

    1993-11-16

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductors allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology. 12 figures.

  15. Superconducting active impedance converter

    DOEpatents

    Ginley, David S.; Hietala, Vincent M.; Martens, Jon S.

    1993-01-01

    A transimpedance amplifier for use with high temperature superconducting, other superconducting, and conventional semiconductor allows for appropriate signal amplification and impedance matching to processing electronics. The amplifier incorporates the superconducting flux flow transistor into a differential amplifier configuration which allows for operation over a wide temperature range, and is characterized by high gain, relatively low noise, and response times less than 200 picoseconds over at least a 10-80 K. temperature range. The invention is particularly useful when a signal derived from either far-IR focal plane detectors or from Josephson junctions is to be processed by higher signal/higher impedance electronics, such as conventional semiconductor technology.

  16. Catalytic Hydrothermal Gasification of Biomass

    SciTech Connect

    Elliott, Douglas C.

    2008-05-06

    A recent development in biomass gasification is the use of a pressurized water processing environment in order that drying of the biomass can be avoided. This paper reviews the research undertaken developing this new option for biomass gasification. This review does not cover wet oxidation or near-atmospheric-pressure steam-gasification of biomass. Laboratory research on hydrothermal gasification of biomass focusing on the use of catalysts is reviewed here, and a companion review focuses on non-catalytic processing. Research includes liquid-phase, sub-critical processing as well as super-critical water processing. The use of heterogeneous catalysts in such a system allows effective operation at lower temperatures, and the issues around the use of catalysts are presented. This review attempts to show the potential of this new processing concept by comparing the various options under development and the results of the research.

  17. Non-catalytic recuperative reformer

    SciTech Connect

    Khinkis, Mark J.; Kozlov, Aleksandr P.; Kurek, Harry

    2015-12-22

    A non-catalytic recuperative reformer has a flue gas flow path for conducting hot flue gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is embedded in the flue gas flow path to permit heat transfer from the hot flue gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorific fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, extended surfaces of metal material such as stainless steel or metal alloy that are high in nickel content are included within at least a portion of the reforming mixture flow path.

  18. Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons

    DOEpatents

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2011-02-01

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  19. Power converter connection configuration

    DOEpatents

    Beihoff, Bruce C.; Kehl, Dennis L.; Gettelfinger, Lee A.; Kaishian, Steven C.; Phillips, Mark G.; Radosevich, Lawrence D.

    2008-11-11

    EMI shielding is provided for power electronics circuits and the like via a direct-mount reference plane support and shielding structure. The thermal support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support forms a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

  20. Catalytic reforming methods

    DOEpatents

    Tadd, Andrew R; Schwank, Johannes

    2013-05-14

    A catalytic reforming method is disclosed herein. The method includes sequentially supplying a plurality of feedstocks of variable compositions to a reformer. The method further includes adding a respective predetermined co-reactant to each of the plurality of feedstocks to obtain a substantially constant output from the reformer for the plurality of feedstocks. The respective predetermined co-reactant is based on a C/H/O atomic composition for a respective one of the plurality of feedstocks and a predetermined C/H/O atomic composition for the substantially constant output.

  1. Radiation effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2000-01-01

    DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

  2. Catalytic considerations in temperature measurement.

    NASA Technical Reports Server (NTRS)

    Ash, R. L.; Crossman, G. R.; Chitnis, R. V.

    1972-01-01

    Literature discussing catalytic activity in platinum group temperature sensors is surveyed. Methods for the determination and/or elimination of catalytic activity are reported. A particular application of the literature is discussed in which it is possible to infer that a shielded platinum total temperature probe does not experience significant catalytic activity in the wake of a supersonic hydrogen burner, while a bare iridium plus rhodium, iridium thermocouple does. It is concluded that catalytic data corrections are restricted and that it is preferable to coat the temperature sensor with a noncatalytic coating. Furthermore, the desirability of transparent coatings is discussed.

  3. A study of Schwarz converters for nuclear powered spacecraft

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A.; Schwarze, Gene E.

    1987-01-01

    High power space systems which use low dc voltage, high current sources such as thermoelectric generators, will most likely require high voltage conversion for transmission purposes. This study considers the use of the Schwarz resonant converter for use as the basic building block to accomplish this low-to-high voltage conversion for either a dc or an ac spacecraft bus. The Schwarz converter has the important assets of both inherent fault tolerance and resonant operation; parallel operation in modular form is possible. A regulated dc spacecraft bus requires only a single stage converter while a constant frequency ac bus requires a cascaded Schwarz converter configuration. If the power system requires constant output power from the dc generator, then a second converter is required to route unneeded power to a ballast load.

  4. A study of Schwarz converters for nuclear powered spacecraft

    SciTech Connect

    Stuart, T.A.; Schwarze, G.E.

    1994-09-01

    High power space systems which use low dc voltage, high current sources such as thermoelectric generators, will most likely require high voltage conversion for transmission purposes. This study considers the use of the Schwarz resonant converter for use as the basic building block to accomplish this low-to-high voltage conversion for either a dc or an ac spacecraft bus. The Schwarz converter has the important assets of both inherent fault tolerance and resonant operation and parallel operation in modular form is possible. A regulated dc spacecraft bus requires only a single stage converter while a constant frequency ac bus requires a cascaded Schwarz converter configuration. If the power system requires constant output power from the dc generator, then a second converter is required to route unneeded power to a ballast load.

  5. Evolution of catalytic RNA in the laboratory

    NASA Technical Reports Server (NTRS)

    Joyce, Gerald F.

    1992-01-01

    We are interested in the biochemistry of existing RNA enzymes and in the development of RNA enzymes with novel catalytic function. The focal point of our research program has been the design and operation of a laboratory system for the controlled evolution of catalytic RNA. This system serves as working model of RNA-based life and can be used to explore the catalytic potential of RNA. Evolution requires the integration of three chemical processes: amplification, mutation, and selection. Amplification results in additional copies of the genetic material. Mutation operates at the level of genotype to introduce variability, this variability in turn being expressed as a range of phenotypes. Selection operates at the level of phenotype to reduce variability by excluding those individuals that do not conform to the prevailing fitness criteria. These three processes must be linked so that only the selected individuals are amplified, subject to mutational error, to produce a progeny distribution of mutant individuals. We devised techniques for the amplification, mutation, and selection of catalytic RNA, all of which can be performed rapidly in vitro within a single reaction vessel. We integrated these techniques in such a way that they can be performed iteratively and routinely. This allowed us to conduct evolution experiments in response to artificially-imposed selection constraints. Our objective was to develop novel RNA enzymes by altering the selection constraints in a controlled manner. In this way we were able to expand the catalytic repertoire of RNA. Our long-range objective is to develop an RNA enzyme with RNA replicase activity. If such an enzyme had the ability to produce additional copies of itself, then RNA evolution would operate autonomously and the origin of life will have been realized in the laboratory.

  6. Supersymmetric mode converters

    NASA Astrophysics Data System (ADS)

    Heinrich, Matthias; Miri, Mohammad-Ali; Stützer, Simon; Nolte, Stefan; Szameit, Alexander; Christodoulides, Demetrios N.

    2015-08-01

    In recent years, the ever-increasing demand for high-capacity transmission systems has driven remarkable advances in technologies that encode information on an optical signal. Mode-division multiplexing makes use of individual modes supported by an optical waveguide as mutually orthogonal channels. The key requirement in this approach is the capability to selectively populate and extract specific modes. Optical supersymmetry (SUSY) has recently been proposed as a particularly elegant way to resolve this design challenge in a manner that is inherently scalable, and at the same time maintains compatibility with existing multiplexing strategies. Supersymmetric partners of multimode waveguides are characterized by the fact that they share all of their effective indices with the original waveguide. The crucial exception is the fundamental mode, which is absent from the spectrum of the partner waveguide. Here, we demonstrate experimentally how this global phase-matching property can be exploited for efficient mode conversion. Multimode structures and their superpartners are experimentally realized in coupled networks of femtosecond laser-written waveguides, and the corresponding light dynamics are directly observed by means of fluorescence microscopy. We show that SUSY transformations can readily facilitate the removal of the fundamental mode from multimode optical structures. In turn, hierarchical sequences of such SUSY partners naturally implement the conversion between modes of adjacent order. Our experiments illustrate just one of the many possibilities of how SUSY may serve as a building block for integrated mode-division multiplexing arrangements. Supersymmetric notions may enrich and expand integrated photonics by versatile optical components and desirable, yet previously unattainable, functionalities.

  7. Novel Catalytic Membrane Reactors

    SciTech Connect

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  8. Catalytic cracking process

    SciTech Connect

    Gladrow, E.M.; Winter, W.E.

    1980-04-29

    The octane number of a cracked naphtha can be significantly improved in a catalytic cracking unit, without significant decrease in naphtha yield, by maintaining certain critical concentrations of metals on the catalyst, suitably by blending or adding a heavy metals-containing component to the gas oil feed. Suitably, in a catalytic cracking process unit wherein a gas oil feed is cracked in a cracking reactor (Zone) at an elevated temperature in the presence of a cracking catalyst, the cracking catalyst is regenerated in a regenerator (Regeneration zone) by burning coke off the catalyst, and catalyst is circulated between the reactor and regenerator, sufficient of a metals-containing heavy feedstock is admixed, intermittantly or continuously, with the gas oil feed to deposit metals on said catalyst and raise the metals-content of said catalyst to a level of from about 1500 to about 6000 parts per million, preferably from about 2500 to about 4000 parts per million expressed as equivalent nickel, base the weight of the catalyst, and said metals level is maintained on the catalyst throughout the operation by withdrawing high metals-containing catalyst and adding low metals-containing catalyst to the regenerator.

  9. Hydrogen from catalytic reforming of biomass-derived hydrocarbons in liquid water.

    PubMed

    Cortright, R D; Davda, R R; Dumesic, J A

    2002-08-29

    Concerns about the depletion of fossil fuel reserves and the pollution caused by continuously increasing energy demands make hydrogen an attractive alternative energy source. Hydrogen is currently derived from nonrenewable natural gas and petroleum, but could in principle be generated from renewable resources such as biomass or water. However, efficient hydrogen production from water remains difficult and technologies for generating hydrogen from biomass, such as enzymatic decomposition of sugars, steam-reforming of bio-oils and gasification, suffer from low hydrogen production rates and/or complex processing requirements. Here we demonstrate that hydrogen can be produced from sugars and alcohols at temperatures near 500 K in a single-reactor aqueous-phase reforming process using a platinum-based catalyst. We are able to convert glucose -- which makes up the major energy reserves in plants and animals -- to hydrogen and gaseous alkanes, with hydrogen constituting 50% of the products. We find that the selectivity for hydrogen production increases when we use molecules that are more reduced than sugars, with ethylene glycol and methanol being almost completely converted into hydrogen and carbon dioxide. These findings suggest that catalytic aqueous-phase reforming might prove useful for the generation of hydrogen-rich fuel gas from carbohydrates extracted from renewable biomass and biomass waste streams. PMID:12198544

  10. Hydrogen from catalytic reforming of biomass-derived hydrocarbons in liquid water

    NASA Astrophysics Data System (ADS)

    Cortright, R. D.; Davda, R. R.; Dumesic, J. A.

    2002-08-01

    Concerns about the depletion of fossil fuel reserves and the pollution caused by continuously increasing energy demands make hydrogen an attractive alternative energy source. Hydrogen is currently derived from nonrenewable natural gas and petroleum, but could in principle be generated from renewable resources such as biomass or water. However, efficient hydrogen production from water remains difficult and technologies for generating hydrogen from biomass, such as enzymatic decomposition of sugars, steam-reforming of bio-oils and gasification, suffer from low hydrogen production rates and/or complex processing requirements. Here we demonstrate that hydrogen can be produced from sugars and alcohols at temperatures near 500K in a single-reactor aqueous-phase reforming process using a platinum-based catalyst. We are able to convert glucose-which makes up the major energy reserves in plants and animals-to hydrogen and gaseous alkanes, with hydrogen constituting 50% of the products. We find that the selectivity for hydrogen production increases when we use molecules that are more reduced than sugars, with ethylene glycol and methanol being almost completely converted into hydrogen and carbon dioxide. These findings suggest that catalytic aqueous-phase reforming might prove useful for the generation of hydrogen-rich fuel gas from carbohydrates extracted from renewable biomass and biomass waste streams.

  11. Integrated mode converter for mode division multiplexing

    NASA Astrophysics Data System (ADS)

    Perez-Galacho, Diego; Alonso-Ramos, Carlos Alberto; Marris-Morini, Delphine; Vakarin, Vladyslav; Le Roux, Xavier; Ortega-Moñux, Alejandro; Wangüemert-Perez, Juan Gonzalo; Vivien, Laurent

    2016-05-01

    The ever growing demands of bandwidth in optical communication systems are making traditional Wavelength Division Multiplexing (WDM) based systems to reach its limit. In order to cope with future bandwidth demand is necessary to use new levels of orthogonality, such as the waveguide mode or the polarization state. Mode Division Multiplexing (MDM) has recently attracted attention as a possible solution to increase aggregate bandwidth. In this work we discuss the proposition a of mode converter that can cover the whole C-Band of optical communications. The Mode Converter is based on two Multimode Interference (MMI) couplers and a phase shifter. Insertion loss (IL) below 0.2 dB and Extinction ratio (ER) higher than 20 dB in a broad bandwidth range of 1.5 μm to 1.6 μm have been estimated. The total length of the device is less than 30 μm.

  12. MOCCASIN: converting MATLAB ODE models to SBML

    PubMed Central

    Gómez, Harold F.; Hucka, Michael; Keating, Sarah M.; Nudelman, German; Iber, Dagmar; Sealfon, Stuart C.

    2016-01-01

    Summary: MATLAB is popular in biological research for creating and simulating models that use ordinary differential equations (ODEs). However, sharing or using these models outside of MATLAB is often problematic. A community standard such as Systems Biology Markup Language (SBML) can serve as a neutral exchange format, but translating models from MATLAB to SBML can be challenging—especially for legacy models not written with translation in mind. We developed MOCCASIN (Model ODE Converter for Creating Automated SBML INteroperability) to help. MOCCASIN can convert ODE-based MATLAB models of biochemical reaction networks into the SBML format. Availability and implementation: MOCCASIN is available under the terms of the LGPL 2.1 license (http://www.gnu.org/licenses/lgpl-2.1.html). Source code, binaries and test cases can be freely obtained from https://github.com/sbmlteam/moccasin. Contact: mhucka@caltech.edu Supplementary information: More information is available at https://github.com/sbmlteam/moccasin. PMID:26861819

  13. Production of hydrogen from biomass by catalytic steam reforming of fast pyrolysis oil

    SciTech Connect

    Czernik, S.; Wang, D.; Chornet, E.

    1998-08-01

    Hydrogen is the prototype of the environmentally cleanest fuel of interest for power generation using fuel cells and for transportation. The thermochemical conversion of biomass to hydrogen can be carried out through two distinct strategies: (a) gasification followed by water-gas shift conversion, and (b) catalytic steam reforming of specific fractions derived from fast pyrolysis and aqueous/steam processes of biomass. This paper presents the latter route that begins with fast pyrolysis of biomass to produce bio-oil. This oil (as a whole or its selected fractions) can be converted to hydrogen via catalytic steam reforming followed by a water-gas shift conversion step. Such a process has been demonstrated at the bench scale using model compounds, poplar oil aqueous fraction, and the whole pyrolysis oil with commercial Ni-based steam reforming catalysts. Hydrogen yields as high as 85% have been obtained. Catalyst initial activity can be recovered through regeneration cycles by steam or CO{sub 2} gasification of carbonaceous deposits.

  14. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, T. R.; Lieb, D.; Oettinger, P. E.; Goodale, D. B.

    1977-01-01

    Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

  15. Perspective view of the front elevation (note: decorative details such ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view of the front elevation (note: decorative details such as the brackets underpinning the deep cornice on the porch and house) - Philip T. Berry House, 1402 Thirty-first Street, Northwest, Washington, District of Columbia, DC

  16. Detail view to show richness of materials such as the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view to show richness of materials such as the Fourteenth Street vestibule with its gilded groin-vaulted ceiling - United States Department of Commerce, Bounded by Fourteenth, Fifteenth, and E streets and Constitution Avenue, Washington, District of Columbia, DC

  17. Catalytic, hollow, refractory spheres, conversions with them

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor); Lee, Mark C. (Inventor); Kendall, Jr., James M. (Inventor)

    1989-01-01

    Improved, heterogeneous, refractory catalysts are in the form of gas-impervious, hollow, thin-walled spheres (10) suitable formed of a shell (12) of refractory such as alumina having a cavity (14) containing a gas at a pressure greater than atmospheric pressure. The wall material may be itself catalytic or a catalytically active material coated onto the sphere as a layer (16), suitably platinum or iron, which may be further coated with a layer (18) of activator or promoter. The density of the spheres (30) can be uniformly controlled to a preselected value within .+-.10 percent of the density of the fluid reactant such that the spheres either remain suspended or slowly fall or rise through the liquid reactant.

  18. Synergize fuel and petrochemical processing plans with catalytic reforming

    SciTech Connect

    1997-03-01

    Depending on the market, refiner`s plans to produce clean fuels and higher value petrochemicals will weigh heavily on the catalytic reformer`s flexibility. It seems that as soon as a timely article related to catalytic reforming operations is published, a new {open_quotes}boutique{close_quotes} gasoline fuel specification is slapped on to existing fuel standards, affecting reformer operations and processing objectives. Just as importantly, the petrochemical market (such as aromatics) that refiners are targeting, can be very fickle. That`s why process engineers have endeavored to maintain an awareness of the flexibility that technology suppliers are building into modern catalytic reformers.

  19. Catalytic reactor with disposable cartridge

    NASA Technical Reports Server (NTRS)

    Mccullough, C. M.

    1973-01-01

    Catalytic reactor, disposable cartridge enclosing iron catalyst, acts as container for solid carbon formed by decomposition of carbon monoxide. Deposition of carbon in other parts of oxygen recovery system does not occur because of lack of catalytic activity; filters trap carbon particles and prevent their being transported outside reaction zone.

  20. Catalytic conversions of chlorodecalin

    SciTech Connect

    Takhistov, U.V.; Kovyazin, V.E.

    1985-10-01

    This paper studies catalytic conversions of chlorinated decahydronaphthalene (chlorodecalin), since the introduction of chlorine into the hydrocarbon molecule would facilitate formation of the original carbonium ion required for conversion to adamantane. Analysis of the fractions obtained showed that two main products are formed: the tricyclic hydrocarbon C/sub 10/H/sub 16/ and the bicyclic hydrocarbon C/sub 10/H/sub 16/. Therefore, the C/sub 10/H/sub 17/ cation formed by removal of chlorine from chlorodecalin, C/sub 10/H/sub 17/CI, undergoes changes in two directions: addition of hydride ions from other chlorodecalin molecules to form Decalin, and loss of a proton to give a tricyclic system of the adamantane weries and its isomer. Introduction of a substituent (chlorine) into the Decalin molecule made it possible to conduct the process at low temperatures.

  1. ``OPTICAL Catalytic Nanomotors''

    NASA Astrophysics Data System (ADS)

    Rosary-Oyong, Se, Glory

    D. Kagan, et.al, 2009:'' a motion-based chemical sensing involving fuel-driven nanomotors is demonstrated. The new protocol relies on the use of an optical microscope for tracking charge in the speed of nanowire motors in the presence of target analyte''. Synthetic nanomotors are propelled by catalytic decomposition of .. they do not require external electric, magnetic or optical fields as energy... Accompanying Fig 2.6(a) of optical micrograph of a partial monolayer of silica microbeads [J.Gibbs, 2011 ] retrieves WF Paxton:''rods were characterized by transmission electron & dark-field optical microscopy..'' & LF Valadares:''dimer due to the limited resolution of optical microscopy, however the result..'. Acknowledged to HE. Mr. Prof. SEDIONO M.P. TJONDRONEGORO.

  2. Bifunctional catalytic electrode

    NASA Technical Reports Server (NTRS)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  3. Acrylamide catalytically inhibits topoisomerase II in V79 cells.

    PubMed

    Sciandrello, Giulia; Mauro, Maurizio; Caradonna, Fabio; Catanzaro, Irene; Saverini, Marghereth; Barbata, Giusi

    2010-04-01

    The vinyl monomer acrylamide is characterized by the presence of an alpha,beta-unsaturated carbonyl group that makes it reactive towards thiol, hydroxyl or amino groups and towards the nucleophilic centers in DNA. The ability of acrylamide to chemically modify protein thiols has prompted us to consider topoisomerase II as one possible target of acrylamide, since agents targeting protein sulfhydryl groups act as either catalytic inhibitors or poisons of topoisomerase II. Nuclear extracts from V79 Chinese hamster cells incubated with acrylamide reduced topoisomerase II activity as inferred by an inability to convert kinetoplast DNA to the decatenated form. Nuclear extracts incubated with acrylamide pre-incubated with DTT converted kinetoplast DNA to the decatenated form, suggesting that acrylamide influences topoisomerase II activity through reaction with sulfhydryl groups on the enzyme. Furthermore, acrylamide did not induce the pBR322 DNA cleavage, as assessed by cleavage assay; thus, it cannot be regarded as a poison of topoisomerase II. As a catalytic inhibitor, acrylamide antagonizes the effect of etoposide, a topoisomerase II poison, as determined by clonogenic assay in V79 cells. This antagonism is confirmed by band depletion assay, from which it can be inferred that acrylamide reduces the level of catalytically active cellular topoisomerase II available for the action of etoposide. PMID:20006698

  4. Designing acoustic-electric strain-gauge converters for sensitive diaphragm elements

    NASA Astrophysics Data System (ADS)

    Chernyak, M. G.; Kovalenko, T. V.

    Analytic expressions and nomograms are obtained to estimate the sensitivity of differential acoustic-electric measuring pressure converter with an error no more than 5% and to choose such an arrangement of strain-gauge converters on its sensitive diaphragm element that would ensure an additive temperature error of the measuring pressure converter less than 10-4 K-1

  5. Polarization converters based on axially symmetric twisted nematic liquid crystal.

    PubMed

    Ko, Shih-Wei; Ting, Chi-Lun; Fuh, Andy Y-G; Lin, Tsung-Hsien

    2010-02-15

    An axially symmetric twisted nematic liquid crystal (ASTNLC) device, based on axially symmetric photoalignment, was demonstrated. Such an ASTNLC device can convert axial (azimuthal) to azimuthal (axial) polarization. The optical properties of the ASTNLC device are analyzed and found to agree with simulation results. The ASTNLC device with a specific device can be adopted as an arbitrary axial symmetric polarization converter or waveplate for axially, azimuthally or vertically polarized light. A design for converting linear polarized light to axially symmetric circular polarized light is also demonstrated. PMID:20389369

  6. Hybrid-mode thermionic converter

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.; Britt, E. J.

    1976-01-01

    Converter's collector electrode has uniform low work-function surface and operates at sufficiently low temperature to produce negligible electron emission. Emitter electrode has main region which has intermediate work-function and auxiliary region which has relatively high work-function surface.

  7. Charge-pump voltage converter

    DOEpatents

    Brainard, John P.; Christenson, Todd R.

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  8. Converting accounts receivable into cash.

    PubMed

    Folk, M D; Roest, P R

    1995-09-01

    In recent years, increasing numbers of healthcare providers have converted their accounts receivable into cash through a process called securitization. This practice has gained popularity because it provides a means to raise capital necessary to healthcare organizations. Although securitization transactions can be complex, they may provide increased financial flexibility to providers as they prepare for continuing change in the healthcare industry. PMID:10145096

  9. High-resolution ionization detector and array of such detectors

    DOEpatents

    McGregor, Douglas S.; Rojeski, Ronald A.

    2001-01-16

    A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

  10. 26. SOME CORES, SUCH AS THESE IN THE BRASS FOUNDRY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. SOME CORES, SUCH AS THESE IN THE BRASS FOUNDRY CA.1950, ARE DIPPED INTO A SOLUTION PRIOR TO BEING BAKED IN THE CORE OVEN BEHIND, TO SET THE RESIN AND CREATE A STRUCTURE STRONG ENOUGH TO HOLD UP AGAINST MOLTEN METAL. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  11. High conductivity electrolyte solutions and rechargeable cells incorporating such solutions

    DOEpatents

    Angell, Charles Austen; Zhang, Sheng-Shui; Xu, Kang

    1998-01-01

    This invention relates generally to electrolyte solvents for use in liquid or rubbery polymer electrolyte solutions as are used, for example, in electrochemical devices. More specifically, this invention relates to sulfonyl/phospho-compound electrolyte solvents and sulfonyl/phospho-compound electrolyte solutions incorporating such solvents.

  12. No Such Thing as "Good Vibrations" in Science

    ERIC Educational Resources Information Center

    Lancaster, Franklin D.

    2011-01-01

    A facilities manager must ensure that a building runs as smoothly and successfully as possible. For college, university, and school managers dealing with laboratories and other spaces for scientific study and research, this means making sure that nothing disrupts experiments and other scientific endeavors. Such disruptions can wreak havoc,…

  13. High conductivity electrolyte solutions and rechargeable cells incorporating such solutions

    DOEpatents

    Angell, C.A.; Zhang, S.S.; Xu, K.

    1998-10-20

    This invention relates generally to electrolyte solvents for use in liquid or rubbery polymer electrolyte solutions as are used, for example, in electrochemical devices. More specifically, this invention relates to sulfonyl/phospho-compound electrolyte solvents and sulfonyl/phospho-compound electrolyte solutions incorporating such solvents. 9 figs.

  14. 6. VIEW SHOWING WOODEN FLUMES ACROSS MARICOPA CANAL. SUCH FLUMES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. VIEW SHOWING WOODEN FLUMES ACROSS MARICOPA CANAL. SUCH FLUMES WERE USED TO CARRY WATER FROM ONE CANAL TO ANOTHER, BEFORE THE CANAL COMPANIES WERE BOUGHT BY THE GOVERNMENT, AND THE SYSTEM UNIFIED. Photographer unknown, no date - Grand Canal, North side of Salt River, Tempe, Maricopa County, AZ

  15. Unsteady catalytic processes and sorption-catalytic technologies

    NASA Astrophysics Data System (ADS)

    Zagoruiko, A. N.

    2007-07-01

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  16. Orion EFT-1 Catalytic Tile Experiment Overview and Flight Measurements

    NASA Technical Reports Server (NTRS)

    Salazar, Giovanni; Amar, Adam; Hyatt, Andrew; Rezin, Marc D.

    2016-01-01

    This paper describes the design and results of a surface catalysis flight experiment flown on the Orion Multipurpose Crew Vehicle during Exploration Flight Test 1 (EFT1). Similar to previous Space Shuttle catalytic tile experiments, the present test consisted of a highly catalytic coating applied to an instrumented TPS tile. However, the present catalytic tile experiment contained significantly more instrumentation in order to better resolve the heating overshoot caused by the change in surface catalytic efficiency at the interface between two distinct materials. In addition to collecting data with unprecedented spatial resolution of the "overshoot" phenomenon, the experiment was also designed to prove if such a catalytic overshoot would be seen in turbulent flow in high enthalpy regimes. A detailed discussion of the results obtained during EFT1 is presented, as well as the challenges associated with data interpretation of this experiment. Results of material testing carried out in support of this flight experiment are also shown. Finally, an inverse heat conduction technique is employed to reconstruct the flight environments at locations upstream and along the catalytic coating. The data and analysis presented in this work will greatly contribute to our understanding of the catalytic "overshoot" phenomenon, and have a significant impact on the design of future spacecraft.

  17. Study of switching transients in high frequency converters

    NASA Technical Reports Server (NTRS)

    Zinger, Donald S.; Elbuluk, Malik E.; Lee, Tony

    1993-01-01

    As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented. A current regulated ac/ac PDM converter built using MCT's and IGBT's is

  18. Parametric study of laser photovoltaic energy converters

    NASA Technical Reports Server (NTRS)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  19. Catalytic Microtube Rocket Igniter

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Deans, Matthew C.

    2011-01-01

    Devices that generate both high energy and high temperature are required to ignite reliably the propellant mixtures in combustion chambers like those present in rockets and other combustion systems. This catalytic microtube rocket igniter generates these conditions with a small, catalysis-based torch. While traditional spark plug systems can require anywhere from 50 W to multiple kW of power in different applications, this system has demonstrated ignition at less than 25 W. Reactants are fed to the igniter from the same tanks that feed the reactants to the rest of the rocket or combustion system. While this specific igniter was originally designed for liquid methane and liquid oxygen rockets, it can be easily operated with gaseous propellants or modified for hydrogen use in commercial combustion devices. For the present cryogenic propellant rocket case, the main propellant tanks liquid oxygen and liquid methane, respectively are regulated and split into different systems for the individual stages of the rocket and igniter. As the catalyst requires a gas phase for reaction, either the stored boil-off of the tanks can be used directly or one stream each of fuel and oxidizer can go through a heat exchanger/vaporizer that turns the liquid propellants into a gaseous form. For commercial applications, where the reactants are stored as gases, the system is simplified. The resulting gas-phase streams of fuel and oxidizer are then further divided for the individual components of the igniter. One stream each of the fuel and oxidizer is introduced to a mixing bottle/apparatus where they are mixed to a fuel-rich composition with an O/F mass-based mixture ratio of under 1.0. This premixed flow then feeds into the catalytic microtube device. The total flow is on the order of 0.01 g/s. The microtube device is composed of a pair of sub-millimeter diameter platinum tubes connected only at the outlet so that the two outlet flows are parallel to each other. The tubes are each

  20. Converting VSAM in COBOL to embedded SQL

    SciTech Connect

    Huang, Hai; Wang, Yamin; Tsai, Wei-Tek

    1996-12-31

    VSAM databases we widely used on IBM mainframe systems. As new technology, such as relational database and client-server computing, becomes popular, there is a need to reengineer the VSAM databases to relational databases. This paper addresses the issues on converting COBOL programs that access VSAM database to COBOL programs that access relational databases with embedded SQL. It proposed a semi-automatic approach to the conversion of VSAM data sets to SQL tables and VSAM operations in COBOL program to embedded SQL queries. The proposed approach has been experimented on several industrial COBOL programs and a tool implementing the approach is under development.

  1. Vapor-Driven Propulsion of Catalytic Micromotors

    PubMed Central

    Dong, Renfeng; Li, Jinxing; Rozen, Isaac; Ezhilan, Barath; Xu, Tailin; Christianson, Caleb; Gao, Wei; Saintillan, David; Ren, Biye; Wang, Joseph

    2015-01-01

    Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors. PMID:26285032

  2. Vapor-Driven Propulsion of Catalytic Micromotors.

    PubMed

    Dong, Renfeng; Li, Jinxing; Rozen, Isaac; Ezhilan, Barath; Xu, Tailin; Christianson, Caleb; Gao, Wei; Saintillan, David; Ren, Biye; Wang, Joseph

    2015-01-01

    Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors. PMID:26285032

  3. Vapor-Driven Propulsion of Catalytic Micromotors

    NASA Astrophysics Data System (ADS)

    Dong, Renfeng; Li, Jinxing; Rozen, Isaac; Ezhilan, Barath; Xu, Tailin; Christianson, Caleb; Gao, Wei; Saintillan, David; Ren, Biye; Wang, Joseph

    2015-08-01

    Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors.

  4. Catalytic properties of the eukaryotic exosome.

    PubMed

    Chlebowski, Aleksander; Tomecki, Rafał; López, María Eugenia Gas; Séraphin, Bertrand; Dziembowski, Andrzej

    2010-01-01

    The eukaryotic exosome complex is built around the backbone of a 9-subunit ring similar to phosporolytic ribonucleases such as RNase PH and polynucleotide phosphorylase (PNPase). Unlike those enzymes, the ring is devoid of any detectable catalytic activities, with the possible exception of the plant version of the complex. Instead, the essential RNA decay capability is supplied by associated hydrolytic ribonucleases belonging to the Dis3 and Rrp6 families. Dis3 proteins are endowed with two different activities: the long known processive 3'-5' exonucleolytic one and the recently discovered endonucleolytic one. Rrp6 proteins are distributive exonucleases. This chapter will review the current knowledge about the catalytic properties of theses nucleases and their interplay within the exosome holocomplex. PMID:21618875

  5. Catalytic properties of the eukaryotic exosome.

    PubMed

    Chlebowski, Aleksander; Tomecki, Rafał; Gas López, María Eugenia; Séraphin, Bertrand; Dziembowski, Andrzej

    2011-01-01

    The eukaryotic exosome complex is built around the backbone of a 9-subunit ring similar to phosporolytic ribonucleases such as RNase PH and polynucleotide phosphorylase (PNPase). Unlike those enzymes, the ring is devoid of any detectable catalytic activities, with the possible exception of the plant version of the complex. Instead, the essential RNA decay capability is supplied by associated hydrolytic ribonucleases belonging to the Dis3 and Rrp6 families. Dis3 proteins are endowed with two different activities: the long known processive 3'-5' exonucleolytic one and the recently discovered endonucleolytic one. Rrp6 proteins are distributive exonucleases. This chapter will review the current knowledge about the catalytic properties of theses nucleases and their interplay within the exosome holocomplex. PMID:21713678

  6. Trash to Gas: Converting Space Trash into Useful Products

    NASA Technical Reports Server (NTRS)

    Nur, Mononita

    2013-01-01

    NASA's Logistical Reduction and Repurposing (LRR) project is a collaborative effort in which NASA is determined to reduce total logistical mass through reduction, reuse and recycling of various wastes and components of long duration space missions and habitats. LRR is focusing on four distinct advanced areas of study: Advanced Clothing System, Logistics-to-Living, Heat Melt Compactor and Trash to Supply Gas (TtSG). The objective of TtSG is to develop technologies that convert material waste, human waste and food waste into high-value products. High-value products include life support oxygen and water, rocket fuels, raw material production feedstocks, and other energy sources. There are multiple pathways for converting waste to products involving single or multi-step processes. This paper discusses thermal oxidation methods of converting waste to methane. Different wastes, including food, food packaging, Maximum Absorbent Garments (MAGs), human waste simulants, and cotton washcloths have been evaluated in a thermal degradation reactor under conditions promoting pyrolysis, gasification or incineration. The goal was to evaluate the degradation processes at varying temperatures and ramp cycles and to maximize production of desirable products and minimize high molecular weight hydrocarbon (tar) production. Catalytic cracking was also evaluated to minimize tar production. The quantities of C02, CO, CH4, and H20 were measured under the different thermal degradation conditions. The conversion efficiencies of these products were used to determine the best methods for producing desired products.

  7. Trash-to-Gas: Converting Space Trash into Useful Products

    NASA Technical Reports Server (NTRS)

    Caraccio, Anne J.; Hintze, Paul E.

    2013-01-01

    NASA's Logistical Reduction and Repurposing (LRR) project is a collaborative effort in which NASA is determined to reduce total logistical mass through reduction, reuse and recycling of various wastes and components of long duration space missions and habitats. LRR is focusing on four distinct advanced areas of study: Advanced Clothing System, Logistics-to-Living, Heat Melt Compactor and Trash to Supply Gas (TtSG). The objective of TtSG is to develop technologies that convert material waste, human waste and food waste into high-value products. High-value products include life support oxygen and water, rocket fuels, raw material production feedstocks, and other energy sources. There are multiple pathways for converting waste to products involving single or multi-step processes. This paper discusses thermal oxidation methods of converting waste to methane. Different wastes, including food, food packaging, Maximum Absorbent Garments (MAGs), human waste simulants, and cotton washcloths have been evaluated in a thermal degradation reactor under conditions promoting pyrolysis, gasification or incineration. The goal was to evaluate the degradation processes at varying temperatures and ramp cycles and to maximize production of desirable products and minimize high molecular weight hydrocarbon (tar) production. Catalytic cracking was also evaluated to minimize tar production. The quantities of CO2, CO, CH4, and H2O were measured under the different thermal degradation conditions. The conversion efficiencies of these products were used to determine the best methods for producing desired products.

  8. Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.

    SciTech Connect

    Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew; Cesarano, Joseph, III; Miller, James Edward

    2004-12-01

    This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application. Practical applications include the combustion of natural gas for power generation, production of syngas, and hydrogen reforming reactions. The robocast lattice structures also show practicality for diesel particulate trapping. Preliminary results for trapping efficiency are reported as well as the development of electrically resistive lattices that can regenerate the structure by combusting the

  9. The elaborate plumage in peacocks is not such a drag.

    PubMed

    Askew, Graham N

    2014-09-15

    One of the classic examples of an exaggerated sexually selected trait is the elaborate plumage that forms the train in male peafowl Pavo cristatus (peacock). Such ornaments are thought to reduce locomotor performance as a result of their weight and aerodynamic drag, but this cost is unknown. Here, the effect that the train has on take-off flight in peacocks was quantified as the sum of the rates of change of the potential and kinetic energies of the body (P(CoM)) in birds with trains and following the train's removal. There was no significant difference between P(CoM) in birds with and without a train. The train incurs drag during take-off; however, while this produces a twofold increase in parasite drag, parasite power only accounts for 0.1% of the total aerodynamic power. The train represented 6.9% of body weight and is expected to increase induced power. The absence of a detectable effect on take-off performance does not necessarily mean that there is no cost associated with possessing such ornate plumage; rather, it suggests that given the variation in take-off performance per se, the magnitude of any effect of the train has little meaningful functional relevance. PMID:25232196

  10. Advanced byproduct recovery: Direct catalytic reduction of sulfur dioxide to elemental sulfur. Second quarterly technical progress report, January--March 1996

    SciTech Connect

    1996-05-01

    In the more than 170 wet scrubber systems in 72,000 MW of US, coal-fired, utility boilers, the SO{sub 2} removed from the boiler flue gas is sorbed, and the sulfated sorbent must be disposed of. The use of regenerable sorbents has the potential to reduce this disposal problem. The team of Arthur D. Little, Tufts Univ., and Engelhard Corp. are conducting Phase I of a 4.5-year, two-phase effort to develop and scale-up a direct, single-stage, catalytic process for converting SO{sub 2} to S. This catalytic process reduces SO{sub 2} over a fluorite-type oxide such as ceria and zirconia; the catalytic activity can be promoted by active transition metals such as Cu. The Phase I program includes the following work elements: market/process/cost/evaluation; lab-scale catalyst preparation/optimization, lab-scale bulk/supported catalyst kinetic studies, bench-scale catalyst/process studies, and utility review.

  11. Advanced byproduct recovery: Direct catalytic reduction of SO{sub 2} to elemental sulfur. First quarterly technical progress report, [October--December 1995

    SciTech Connect

    Benedek, K.; Flytzani-Stephanopoulos, M.

    1996-02-01

    The team of Arthur D. Little, Tufts University and Engelhard Corporation will be conducting Phase I of a four and a half year, two-phase effort to develop and scale-up an advanced byproduct recovery technology that is a direct, single-stage, catalytic process for converting sulfur dioxide to elemental sulfur. this catalytic process reduces SO{sub 2} over a fluorite-type oxide (such as ceria or zirconia). The catalytic activity can be significantly promoted by active transition metals, such as copper. More than 95% elemental sulfur yield, corresponding to almost complete sulfur dioxide conversion, was obtained over a Cu-Ce-O oxide catalyst as part of an ongoing DOE-sponsored University Coal Research Program. This type of mixed metal oxide catalyst has stable activity, high selectivity for sulfur production, and is resistant to water and carbon dioxide poisoning. Tests with CO and CH{sub 4} reducing gases indicates that the catalyst has the potential for flexibility with regard to the composition of the reducing gas, making it attractive for utility use. the performance of the catalyst is consistently good over a range of SO{sub 2} inlet concentration (0.1 to 10%) indicating its flexibility in treating SO{sub 2} tail gases as well as high concentration streams.

  12. Catalytic processes in the atmospheres of earth and Venus

    NASA Astrophysics Data System (ADS)

    Demore, W. B.; Yung, Y. L.

    1982-09-01

    Photochemical processes in planetary atmospheres are strongly influenced by catalytic effects of minor constituents. Catalytic cycles in the atmospheres of Earth and Venus are closely related. For example, chlorine oxides (ClOx) act as catalysts in the two atmospheres. On earth, they serve to convert odd oxygen (atomic oxygen and ozone) to molecular oxygen. On Venus they have a similar effect, but in addition they accelerate the reactions of atomic and molecular oxygen with carbon monoxide. The latter process occurs by a unique combination of ClOx catalysis and sulful dioxide photosensitization. The mechanism provides an explanation for the very low extent of carbon dioxide decomposition by sunlight in the Venus atmosphere.

  13. Catalytic processes in the atmospheres of earth and Venus

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Yung, Y. L.

    1982-01-01

    Photochemical processes in planetary atmospheres are strongly influenced by catalytic effects of minor constituents. Catalytic cycles in the atmospheres of Earth and Venus are closely related. For example, chlorine oxides (ClOx) act as catalysts in the two atmospheres. On earth, they serve to convert odd oxygen (atomic oxygen and ozone) to molecular oxygen. On Venus they have a similar effect, but in addition they accelerate the reactions of atomic and molecular oxygen with carbon monoxide. The latter process occurs by a unique combination of ClOx catalysis and sulful dioxide photosensitization. The mechanism provides an explanation for the very low extent of carbon dioxide decomposition by sunlight in the Venus atmosphere.

  14. Photoelectric converters with quantum coherence.

    PubMed

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency η_{CA}. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to η_{CA} through manipulation of carefully controlled quantum coherences. PMID:27300826

  15. Vibration converter with magnetic levitation

    NASA Astrophysics Data System (ADS)

    Gladilin, A. V.; Pirogov, V. A.; Golyamina, I. P.; Kulaev, U. V.; Kurbatov, P. A.; Kurbatova, E. P.

    2015-05-01

    The paper presents a mathematical model, the results of computational and theoretical research, and the feasibility of creating a vibration converter with full magnetic levitation in the suspension of a high-temperature superconductor (HTSC). The axial and radial stability of the active part of the converter is provided by the interaction of the magnetic field of ring-shaped permanent magnets and a hollow cylinder made of the ceramic HTSC material. The force is created by a system of current-carrying coils whose magnetic field is polarized by permanent magnets and interacts with induced currents in the superconducting cylinder. The case of transition to the superconducting state of HTSC material in the field of the permanent magnets (FC mode) is considered. The data confirm the outlook for the proposed technical solutions.

  16. Photoelectric converters with quantum coherence

    NASA Astrophysics Data System (ADS)

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency ηCA. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to ηCA through manipulation of carefully controlled quantum coherences.

  17. Catalytic Mechanisms for Phosphotriesterases

    PubMed Central

    Bigley, Andrew N.; Raushel, Frank M.

    2012-01-01

    Phosphotriesters are one class of highly toxic synthetic compounds known as organophosphates. Wide spread usage of organophosphates as insecticides as well as nerve agents has lead to numerous efforts to identify enzymes capable of detoxifying them. A wide array of enzymes has been found to have phosphotriesterase activity including phosphotriesterase (PTE), methyl parathion hydrolase (MPH), organophosphorus acid anhydrolase (OPAA), diisopropylfluorophosphatase (DFP), and paraoxonase 1 (PON1). These enzymes differ widely in protein sequence and three-dimensional structure, as well as in catalytic mechanism, but they also share several common features. All of the enzymes identified as phosphotriesterases are metal-dependent hydrolases that contain a hydrophobic active site with three discrete binding pockets to accommodate the substrate ester groups. Activation of the substrate phosphorus center is achieved by a direct interaction between the phosphoryl oxygen and a divalent metal in the active site. The mechanistic details of the hydrolytic reaction differ among the various enzymes with both direct attack of a hydroxide as well as covalent catalysis being found. PMID:22561533

  18. Simplified dc to dc converter

    NASA Technical Reports Server (NTRS)

    Gruber, R. P. (Inventor)

    1984-01-01

    A dc to dc converter which can start with a shorted output and which regulates output voltage and current is described. Voltage controlled switches directed current through the primary of a transformer the secondary of which includes virtual reactance. The switching frequency of the switches is appropriately varied to increase the voltage drop across the virtual reactance in the secondary winding to which there is connected a low impedance load. A starting circuit suitable for voltage switching devices is provided.

  19. Catalytic conversion of nonfood woody biomass solids to organic liquids.

    PubMed

    Barta, Katalin; Ford, Peter C

    2014-05-20

    This Account outlines recent efforts in our laboratories addressing a fundamental challenge of sustainability chemistry, the effective utilization of biomass for production of chemicals and fuels. Efficient methods for converting renewable biomass solids to chemicals and liquid fuels would reduce society's dependence on nonrenewable petroleum resources while easing the atmospheric carbon dioxide burden. The major nonfood component of biomass is lignocellulose, a matrix of the biopolymers cellulose, hemicellulose, and lignin. New approaches are needed to effect facile conversion of lignocellulose solids to liquid fuels and to other chemical precursors without the formation of intractable side products and with sufficient specificity to give economically sustainable product streams. We have devised a novel catalytic system whereby the renewable feedstocks cellulose, organosolv lignin, and even lignocellulose composites such as sawdust are transformed into organic liquids. The reaction medium is supercritical methanol (sc-MeOH), while the catalyst is a copper-doped porous metal oxide (PMO) prepared from inexpensive, Earth-abundant starting materials. This transformation occurs in a single stage reactor operating at 300-320 °C and 160-220 bar. The reducing equivalents for these transformations are derived by the reforming of MeOH (to H2 and CO), which thereby serves as a "liquid syngas" in the present case. Water generated by deoxygenation processes is quickly removed by the water-gas shift reaction. The Cu-doped PMO serves multiple purposes, catalyzing substrate hydrogenolysis and hydrogenation as well as the methanol reforming and shift reactions. This one-pot "UCSB process" is quantitative, giving little or no biochar residual. Provided is an overview of these catalysis studies beginning with reactions of the model compound dihydrobenzofuran that help define the key processes occurring. The initial step is phenyl-ether bond hydrogenolysis, and this is followed by

  20. Size-dependent catalytic activity of supported metal clusters

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Xiao, F.-S.; Purnell, S. K.; Alexeev, O.; Kawi, S.; Deutsch, S. E.; Gates, B. C.

    1994-11-01

    BECAUSE catalysis by metals is a surface phenomenon, many technological catalysts contain small (typically nanometre-sized) supported metal particles with a large fraction of the atoms exposed1. Many reactions, such as hydrocarbon hydrogenations, are structure-insensitive, proceeding at approximately the same rate on metal particles of various sizes provided that they are larger than about 1 nm and show bulk-like metallic behaviour1. But it is not known whether the catalytic properties of metal particles become size-dependent as the particles become so small that they are no longer metallic in character. Here we investigate the catalytic behaviour of precisely defined clusters of just four and six iridium atoms on solid supports. We find that the Ir4 and Ir6 clusters differ in catalytic activity both from each other and from metallic Ir particles. This raises the possibility of tailoring the catalytic behaviour of metal clusters by controlling the cluster size.

  1. Hybrid nanomotor: a catalytically/magnetically powered adaptive nanowire swimmer.

    PubMed

    Gao, Wei; Manesh, Kalayil Manian; Hua, Joe; Sattayasamitsathit, Sirilak; Wang, Joseph

    2011-07-18

    A synthetic hybrid nanomotor, which combines chemically powered propulsion and magnetically driven locomotion, is described. The new catalytic-magnetic nanomotor consists of a flexible multisegment Pt-Au-Ag(flex)-Ni nanowire, with the Pt-Au and Au-Ag(flex)-Ni portions responsible for the catalytic and magnetic propulsion modes, respectively. The experimental data and theoretical considerations indicate that the hybrid design only minimally compromises the individual propulsion modes. Rapid and convenient switching from the catalytic to the magnetic mode is illustrated. The resulting catalytic-magnetic adaptive nanomotor can address the fuel depletion and salt limitation common to chemically powered motors by switching to magnetic propulsion. Reversal of the motion direction is also achieved upon applying the magnetic field. Such use of two sources to power a hybrid device offers a broader scope of operation and holds considerable promise for designing adaptive nanovehicles that reconfigure their operation in response to environmental changes or unexpected events. PMID:21626685

  2. Recent advancements in photonic converters

    NASA Astrophysics Data System (ADS)

    Hayduk, Michael J.; Bussjager, Rebecca J.; Getbehead, Mark A.; Louthain, James A.

    2000-09-01

    Analog-to-digital converters (ADCs) are an essential component of digital receiver systems. Progress at advancing the electronic ADC modules has been very slow due in large part to the difficulties in fabricating the electronic circuitry required for very high resolution and high sampling rate converters. This slow progress has resulted in a bottleneck between the received analog signal and the digital signal processing system. Single or multiple analog signal down conversion stages are required in digital receivers to down convert the received analog signal to an intermediate frequency (IF) that can be processed by the electronic ADC. There has been much recent interest in the use of photonics for direct digitization of the analog signal at the received RF frequency thus eliminating the need for analog down conversion. This paper reviews some of the recent research advancements in photonic ADCs. We will especially focus on the development of a novel photonic ADC module that uses semiconductor saturable absorbers to perform the data quantization. We will also present recent results in the development of a mode-locked fiber laser used as the sampling source in this photonic ADC architecture.

  3. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, D. P.; Oettinger, P. E.

    1976-01-01

    The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

  4. Attraction of undulatory swimmers, such as nematodes, to surfaces

    NASA Astrophysics Data System (ADS)

    Yuan, Jinzhou; Raizen, David; Bau, Haim

    2014-11-01

    Nematodes play a significant role in the ecosystem; agriculture; human, animal, and plant disease; and medical research. The interactions between nematodes and surfaces may play an important role in nematodes' life cycle and ability to invade a host. We studied the effect of a surface on the dynamics of low-Reynolds number, undulating swimmers such as Caenorhabditis (C.) elegans -both wild type and touch-insensitive. The experiments demonstrated that swimmers located far from a surface selected randomly their direction of motion. In contrast, surface-proximate swimmers rotated towards, collided with, and swam along the surface for considerable time intervals, periodically contacting the surface with their anterior. Likewise, swimmers in a swarm were present at higher concentrations close to the surface. Both resistive force theory-based calculations and symmetry arguments predict that short range hydrodynamic torque, resulting from the interaction between the swimmer-induced flow field and the surface, rotate the swimmer towards the surface. We conclude that the surface attraction and following results from the interplay between short-range hydrodynamic and steric forces and is genotype-independent. The work was supported, in part, by NIH NIA 5R03AG042690-02 and NBIC NSF NSEC DMR08-32802.

  5. There is no such thing as a biocompatible material.

    PubMed

    Williams, David F

    2014-12-01

    This Leading Opinion Paper discusses a very important matter concerning the use of a single word in biomaterials science. This might be considered as being solely concerned with semantics, but it has implications for the scientific rationale for biomaterials selection and the understanding of their performance. That word is the adjective 'biocompatible', which is often used to characterize a material property. It is argued here that biocompatibility is a perfectly acceptable term, but that it subsumes a variety of mechanisms of interaction between biomaterials and tissues or tissue components and can only be considered in the context of the characteristics of both the material and the biological host within which it placed. De facto it is a property of a system and not of a material. It follows that there can be no such thing as a biocompatible material. It is further argued that in those situations where it is considered important, or necessary, to use a descriptor of biocompatibility, as in a scientific paper, a regulatory submission or in a legal argument, the phrase 'intrinsically biocompatible system' would be the most appropriate. The rationale for this linguistic restraint is that far too often it has been assumed that some materials are 'universally biocompatible' on the basis of acceptable clinical performance in one situation, only for entirely unacceptable performance to ensue in quite different clinical circumstances. PMID:25263686

  6. Catalytic Enantioselective Synthesis of Halocyclopropanes.

    PubMed

    Pons, Amandine; Ivashkin, Pavel; Poisson, Thomas; Charette, André B; Pannecoucke, Xavier; Jubault, Philippe

    2016-04-25

    A catalytic asymmetric synthesis of halocyclopropanes is described. The developed method is based on a carbenoid cyclopropanation of 2-haloalkenes with tert-butyl α-cyano-α-diazoacetate using a chiral rhodium catalyst that permits access to a broad range of highly functionalized chiral halocyclopropanes (F, Cl, Br, and I) in good yields, moderate diastereoselectivity, and excellent enantiomeric ratios. The reported methodology represents the first general catalytic enantioselective approach to halocyclopropanes. PMID:26945553

  7. Halogen Chemistry on Catalytic Surfaces.

    PubMed

    Moser, Maximilian; Pérez-Ramírez, Javier

    2016-01-01

    Halogens are key building blocks for the manufacture of high-value products such as chemicals, plastics, and pharmaceuticals. The catalytic oxidation of HCl and HBr is an attractive route to recover chlorine and bromine in order to ensure the sustainability of the production processes. Very few materials withstand the high corrosiveness and the strong exothermicity of the reactions and among them RuO2 and CeO2-based catalysts have been successfully applied in HCl oxidation. The search for efficient systems for HBr oxidation was initiated by extrapolating the results of HCl oxidation based on the chemical similarity of these reactions. Interestingly, despite its inactivity in HCl oxidation, TiO2 was found to be an outstanding HBr oxidation catalyst, which highlighted that the latter reaction is more complex than previously assumed. Herein, we discuss the results of recent comparative studies of HCl and HBr oxidation on both rutile-type (RuO2, IrO2, and TiO2) and ceria-based catalysts using a combination of advanced experimental and theoretical methods to provide deeper molecular-level understanding of the reactions. This knowledge aids the design of the next-generation catalysts for halogen recycling. PMID:27131113

  8. Catalytic reactions in ionic liquids.

    PubMed

    Sheldon, R

    2001-12-01

    The chemical industry is under considerable pressure to replace many of the volatile organic compounds (VOCs) that are currently used as solvents in organic synthesis. The toxic and/or hazardous properties of many solvents, notably chlorinated hydrocarbons, combined with serious environmental issues, such as atmospheric emissions and contamination of aqueous effluents is making their use prohibitive. This is an important driving force in the quest for novel reaction media. Curzons and coworkers, for example, recently noted that rigorous management of solvent use is likely to result in the greatest improvement towards greener processes for the manufacture of pharmaceutical intermediates. The current emphasis on novel reaction media is also motivated by the need for efficient methods for recycling homogeneous catalysts. The key to waste minimisation in chemicals manufacture is the widespread substitution of classical 'stoichiometric' syntheses by atom efficient, catalytic alternatives. In the context of homogeneous catalysis, efficient recycling of the catalyst is a conditio sine qua non for economically and environmentally attractive processes. Motivated by one or both of the above issues much attention has been devoted to homogeneous catalysis in aqueous biphasic and fluorous biphasic systems as well as in supercritical carbon dioxide. Similarly, the use of ionic liquids as novel reaction media may offer a convenient solution to both the solvent emission and the catalyst recycling problem. PMID:12239988

  9. Non-synchronous control of self-oscillating resonant converters

    DOEpatents

    Glaser, John Stanley; Zane, Regan Andrew

    2002-01-01

    A self-oscillating switching power converter has a controllable reactance including an active device connected to a reactive element, wherein the effective reactance of the reactance and the active device is controlled such that the control waveform for the active device is binary digital and is not synchronized with the switching converter output frequency. The active device is turned completely on and off at a frequency that is substantially greater than the maximum frequency imposed on the output terminals of the active device. The effect is to vary the average resistance across the active device output terminals, and thus the effective output reactance, thereby providing converter output control, while maintaining the response speed of the converter.

  10. Converting baker's waste into alcohol. Revised final progress report

    SciTech Connect

    Halsey, R.; Wilson, P.B.

    1982-01-01

    All types of baker's waste (including waste from candy manufacturers) can be converted into alcohol to be used as a fuel. All types of waste at any stage in process can be converted, such as: basic ingredients (including floor sweepings); dry mixes (including floor sweepings); dough at any stage; partially or fully cooked products; and day old returned products. The basic steps are the same, only the initial preparation will vary slightly. The variation will be: amount of water to be added and amount and type of nutrients (if any) to be added. The basic steps are: slurrying, liquefying to put starch into liquid state, saccharifying to convert starch into fermentable sugars, fermentation to convert sugars into alcohol, and distillation to separate the alcohol from the mash. Each step is discussed in detail along with problems that may arise. Directions are given and materials (enzymes, yeast, etc.) and equipment are descibed briefly.

  11. Electrometric direct current I/V converter with wide bandwidth.

    PubMed

    Holt, S; Skyba, P

    2012-06-01

    A principle of operation and electrical characteristics of a high frequency current-to-voltage (I/V) converter are presented. The I/V converter measures the electric current with selectable gains of 10(5), 10(4), and 10(3) V/A in the frequency range from DC to 500 kHz, 1.2 MHz, and 2.4 MHz, respectively. These properties make this I/V converter suitable for wide range of applications such as tuning forks, torsion oscillators, ultrasound transducers measurements, detection of the piezoelectric transducers used in STM techniques, etc., in low temperature physics. The influence of the input impedance of a I/V converter on the precision of alternating current measurements is also discussed. PMID:22755647

  12. Is there such thing as "vaccine against aging"?

    PubMed

    Davidovic, M; Milosevic, D P; Despotovic, N; Sekularac, N; Erceg, P

    2007-01-01

    Problem could be found in the fact that very often we look for one deciding, definitive reason for the process of aging. It is a sort of search for a big discovery, like a fountain of youth or such. More and more authors are trying to explain the unknowns in the understanding of these observations about ageing, by adding the statement that there are two subgroups in the general population. This acknowledgement of two subpopulations explains why there are numerous cases that can not be explained or defined or fitted in these basic observations about caloric restrictions and the delay of reproduction. The identification of those two groups would allow us to find more realistic results in studies, and therefore a more efficient therapy of certain diseases. This hypothesis does not contradict theories of aging that we have accepted (at least not the majority of accepted theories), and this hypothesis also does not contradict the fact that there is a large interindividual variability. This hypothesis doubts, and claims there are exceptions to the starting assumption of geriatrics and gerontology's that: "parallel to the aging process the functions of all organs and organ systems lessen". In future we could use one of these screening tools to detect genetic instable population: the cytokinesis-block micronucleus assay, expression of hTERT, the component of the enzyme telomerase, identification of the "longevity" genes like daf-16, p53, THO, HSP70 or the level of insulin-growth factor-I. This would enable us to correct genetic instability in this population with "vaccine of youth", making the human race living 30 years longer with excellent life quality. PMID:18306689

  13. Catalytic Asymmetric Hydroamination of Unactivated Internal Olefins to Aliphatic Amines

    PubMed Central

    Yang, Yang; Shi, Shi-Liang; Niu, Dawen; Liu, Peng; Buchwald, Stephen L.

    2015-01-01

    Catalytic assembly of enantiopure aliphatic amines from abundant and readily available precursors has long been recognized as a paramount challenge in synthetic chemistry. Herein, we describe a mild and general copper-catalyzed hydroamination that effectively converts unactivated internal olefins, an important yet unexploited class of abundant feedstock chemicals, into highly enantioenriched α-branched amines (≥ 96% enantiomeric excess) featuring two minimally differentiated aliphatic substituents. This method provides a powerful means to access a broad range of advanced, highly functionalized enantioenriched amines of interest in pharmaceutical research and other areas. PMID:26138973

  14. Deep catalytic cracking, maximize olefin production

    SciTech Connect

    Chapin, L.; Letzsch, W. )

    1994-01-01

    Recent environmental regulations coupled with lead phase out have shifted the focus of the FCC from that of an octane barrel machine to that of a light olefins generator. The light olefins are the necessary feedstock for premium reformulated gasoline (RFG) blending components such as MTBE, TAME and alkylate. The demand for these light olefins will impact the operation of the FCC and Steam Cracker (SC). There will be a need for economical olefin generating processing alternatives to supplement SC's for C[sub 3]= and FCC's for C[sub 3]= through C[sub 5]= RFG component feedstocks. To this end, Stone Webster has recently entered into an agreement with the Research Institute of Petroleum Processing (RIPP) and Sinopec International, both located in the People's Republic of China, to exclusively license RIPP's Deep Catalytic Cracking (DCC) technology outside of China. DCC is a newly developed catalytic cracking process for producing light olefins (C[sub 3]--C[sub 5]) from heavy feedstocks. DCC is a fluidized bed process for selectively cracking a variety of hydrocarbon feedstocks to light olefins. Unlike s steam cracker, the predominate products are propylenes and butylenes, the direct result of catalytic cracking rather than free radical thermal reactions. There are two distinct modes of DCC operation: maximum propylene (Type 1) and maximum iso-olefin production (Type 2). Each mode of operation employs a unique catalyst as well as reaction conditions.

  15. Catalytically induced electrokinetics for motors and micropumps.

    PubMed

    Paxton, Walter F; Baker, Paul T; Kline, Timothy R; Wang, Yang; Mallouk, Thomas E; Sen, Ayusman

    2006-11-22

    We have explored the role of electrokinetics in the spontaneous motion of platinum-gold nanorods suspended in hydrogen peroxide (H2O2) solutions that may arise from the bimetallic electrochemical decomposition of H2O2. The electrochemical decomposition pathway was confirmed by measuring the steady-state short-circuit current between platinum and gold interdigitated microelectrodes (IMEs) in the presence of H2O2. The resulting ion flux from platinum to gold implies an electric field in the surrounding solution that can be estimated from Ohm's Law. This catalytically generated electric field could in principle bring about electrokinetic effects that scale with the Helmholtz-Smoluchowski equation. Accordingly, we observed a linear relationship between bimetallic rod speed and the resistivity of the bulk solution. Previous observations relating a decrease in speed to an increase in ethanol concentration can be explained in terms of a decrease in current density caused by the presence of ethanol. Furthermore, we found that the catalytically generated electric field in the solution near a Pt/Au IME in the presence of H2O2 is capable of inducing electroosmotic fluid flow that can be switched on and off externally. We demonstrate that the velocity of the fluid flow in the plane of the IME is a function of the electric field, whether catalytically generated or applied from an external current source. Our findings indicate that the motion of PtAu nanorods in H2O2 is primarily due to a catalytically induced electrokinetic phenomenon and that other mechanisms, such as those related to interfacial tension gradients, play at best a minor role. PMID:17105298

  16. Catalytic and non-catalytic pyrolysis of biomass in non-inert environments for production of deoxygenated bio-oil and chemicals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fast pyrolysis processes are among the most effective methods for liquefaction of lignocellulosic biomass. Catalytic fast pyrolysis (CFP) over HZSM-5 or other zeolites and/or utilization of reactive atmospheres such as in the non-catalytic Tail Gas Reactive Pyrolysis (TRGP) process, a recent patent...

  17. Nickel affects xylem Sap RNase a and converts RNase A to a urease

    PubMed Central

    2013-01-01

    Background Nickel (Ni) is an essential micronutrient; however, its metabolic or physiological functions in plants and animals are largely uncharacterized. The ribonucleases (RNase, e.g., RNase A) are a large family of hydrolases found in one form or many forms facilitating nitrogen (N) cycling. It is currently unknown how either a deficiency or excess of Ni influences the functionality of ribonucleases, like RNase A. This is especially true for perennial crops possessing relatively high Ni requirements. Results We report that the 'rising’ xylem sap of pecan [Carya illinoinensis (Wangenh.) K. Koch, a long-lived tree] at bud break contains a 14 kDa RNase A (aka, RNase 1), which amount has a 33% greater in Ni-deficient as in Ni-sufficient trees when exposed to Ni ions exhibits ureolytic activity. The homologous 13.4 kDa bovine pancreatic RNase A likewise exhibits ureolytic activity upon exposure to Ni ions. Ni therefore affects enzymatic function of a typically non-metalloenzyme, such as it transforms to an enzyme capable of hydrolyzing a linear amide; thus, converting an endonuclease esterase into a urease. Conclusions We conclude that Ni potentially affects the level and activity of RNase A present in the spring xylem sap of pecan trees, and probably in other crops, it has the same influence. The catalytic property of RNase A appears to shift from a nuclease to a urease relying on Ni exposure. This is suggestive that RNase A might possess novel metabolic functionality regarding N-metabolism in perennial plants. The ability of Ni to convert the activity of plant and animal RNase A from that of a ribonuclease to a urease indicates a possible unrecognized beneficial metabolic function of Ni in organisms, while also identifying a potential detrimental effect of excessive Ni on N related metabolic activity if there is sufficient disruption of Ni homeostasis. PMID:24320827

  18. Large wind energy converter: Growian 3 MW

    NASA Technical Reports Server (NTRS)

    Koerber, F.; Thiele, H. A.

    1979-01-01

    The main features of the Growian wind energy converter are presented. Energy yield, environmental impact, and construction of the energy converter are discussed. Reliability of the windpowered system is assessed.

  19. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z.

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  20. Analysis of high voltage step-up nonisolated DC-DC boost converters

    NASA Astrophysics Data System (ADS)

    Alisson Alencar Freitas, Antônio; Lessa Tofoli, Fernando; Junior, Edilson Mineiro Sá; Daher, Sergio; Antunes, Fernando Luiz Marcelo

    2016-05-01

    A high voltage step-up nonisolated DC-DC converter based on coupled inductors suitable to photovoltaic (PV) systems applications is proposed in this paper. Considering that numerous approaches exist to extend the voltage conversion ratio of DC-DC converters that do not use transformers, a detailed comparison is also presented among the proposed converter and other popular topologies such as the conventional boost converter and the quadratic boost converter. The qualitative analysis of the coupled-inductor-based topology is developed so that a design procedure can be obtained, from which an experimental prototype is implemented to validate the theoretical assumptions.

  1. Analysis of a class of pulse modulated dc-to-dc power converters

    NASA Technical Reports Server (NTRS)

    Burger, P.

    1975-01-01

    The basic operational characteristics of dc-to-dc converters are analyzed. The basic physical characteristics of power converters are identified. A simple class of dc-to-dc power converters is chosen which could satisfy any set of operating requirements. Three different controlling methods in this class are described in detail. Necessary conditions for the stability of these converters are measured through analog computer simulation. These curves are related to other operational characteristics, such as ripple and regulation. Finally, further research is suggested for the solution of the physical design of absolutely stable, reliable, and efficient power converters of this class.

  2. Orthogonal-core type three-phase dc-ac converter

    SciTech Connect

    Ichinokura, O.; Saito, H.; Jinzenji, T. ); Tajima, K. )

    1993-03-01

    In a previous paper, the authors proposed an orthogonal-core type dc-ac converter for use in photovoltaic power systems. The dc-ac converter has such desirable features as a simple construction, high degree of safety, and ease of maintenance. The operating characteristics of a single-phase converter for residential photovoltaic power systems have also been reported. In this paper, the authors discuss the basic operation of an orthogonal-core type dc-ac converter for a three-phase power system based on simulations and experiments. An optimal construction of the orthogonal-core type three-phase dc-ac converter has been developed.

  3. Voltage balanced multilevel voltage source converter system

    DOEpatents

    Peng, F.Z.; Lai, J.S.

    1997-07-01

    Disclosed is a voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means. 15 figs.

  4. Voltage balanced multilevel voltage source converter system

    DOEpatents

    Peng, Fang Zheng; Lai, Jih-Sheng

    1997-01-01

    A voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means.

  5. Catalytic pyrolysis of car tire waste using expanded perlite.

    PubMed

    Kar, Y

    2011-08-01

    In this study, the non-catalytic and catalytic pyrolysis experiments were conducted on the sample of tire waste using expanded perlite as an additive material to determine especially the effect of temperature and catalyst-to-tire ratio on the products yields and the compositions and qualities of pyrolytic oils (NCPO and CPO). Non-catalytic studies, which were carried out under the certain conditions (a nitrogen flow of 100mL/min and a heating rate of 10°C/min), showed that the highest yield of pyrolytic oil (NCPO) was 60.02wt.% at 425°C. Then, the catalytic pyrolysis studies were carried out at catalyst-to-tire ratio range of 0.05-0.25 and the highest catalytic pyrolytic oil (CPO) yield was 65.11wt.% at the ratio of 0.10 with the yield increase of 8.48wt.% compared with the non-catalytic pyrolysis. Lastly, the pyrolytic oils were characterized with applying a various techniques such as elemental analyses and various chromatographic and spectroscopic techniques (GC-MS, (1)H NMR, FT-IR, etc.). The characterization results revealed that the pyrolytic oils which were complex mixtures of C(5)-C(15) organic compounds (predominantly aromatic compounds) and also the CPO compared to the NCPO was more similar to conventional fuels in view of the certain fuel properties. PMID:21543218

  6. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  7. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option of the...

  8. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  9. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  10. Boosting the value of biodiesel byproduct by the non-catalytic transesterification of dimethyl carbonate via a continuous flow system under ambient pressure.

    PubMed

    Kwon, Eilhann E; Yi, Haakrho; Jeon, Young Jae

    2014-10-01

    Transformation of coconut oil into biodiesel by using dimethyl carbonate (DMC) via a non-catalytic transesterification reaction under ambient pressure was investigated in this study. The non-catalytic transformation to biodiesel was achieved by means of a heterogeneous reaction between liquid triglycerides and gas phase DMC. The reaction was enhanced in the presence of porous material due to its intrinsic physical properties such as tortuosity and absorption/adsorption. The numerous pores in the material served as micro reaction chambers and ensured that there was enough contact time between the liquid triglycerides and the gaseous DMC, which enabled the completion of the transesterification. The highest fatty acid methyl esters (FAMEs) yield achieved was 98±0.5% within 1-2min at a temperature of 360-450°C under ambient pressure. The fast reaction rates made it possible to convert the lipid feedstock into biodiesel via a continuous flow system without the application of increased pressure. This suggested that the commonly used supercritical conditions could be avoided, resulting in huge cost benefits for biodiesel production. In addition, the high value of the byproduct from the transesterification of the lipid feedstock with DMC suggested that the production biodiesel using this method could be more economically competitive. Finally, the basic properties of biodiesel derived from the non-catalytic conversion of rapeseed oil with DMC were summarised. PMID:25065794

  11. A Sinter-Resistant Catalytic System Based on Platinum Nanoparticles Supported on TiO2 Nanofibers and Covered by Porous Silica

    SciTech Connect

    Dai, Yunqian; Lim, Byungkwon; Yang, Yong; Cobley, Claire M.; Li, Weiyang; Cho, Eun Chul; Grayson, Benjamin; Fanson, Paul T.; Campbell, Charles T.; Sun, Yueming; Xia, Younan

    2010-10-25

    Platinum is a key catalyst that is invaluable in many important industrial processes such as CO oxidation in catalytic converters, oxidation and reduction reactions in fuel cells, nitric acid production, and petroleum cracking.[1] Many of these applications utilize Pt nanoparticles supported on oxides or porous carbon.[2] However, in practical applications that involve high temperatures (typically higher than 3008C), the Pt nanoparticles tend to lose their specific surface area and thus catalytic activity during operation because of sintering. Recent studies have shown that a porous oxide shell can act as a physical barrier to prevent sintering of unsupported metal nanoparticles and, at the same time, provide channels for chemical species to reach the surface of the nanoparticles, thus allowing the catalytic reaction to occur. This concept has been demonstrated in several systems, including Pt@SiO2,[3] Pt@CoO,[4] Pt/CeO2@SiO2,[5] Pd@SiO2,[6] Au@SiO2,[7] Au@SnO2 [8] and Au@ZrO2 [9] core– shell nanostructures. Despite these results, a sinter-resistant system has not been realized in supported Pt nanoparticle catalysts.

  12. Early Oscillation Detection for DC/DC Converter Fault Diagnosis

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2011-01-01

    The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

  13. Investigations on a hybrid positron source with a granular converter

    NASA Astrophysics Data System (ADS)

    Artru, X.; Chaikovska, I.; Chehab, R.; Chevallier, M.; Dadoun, O.; Furukawa, K.; Guler, H.; Kamitani, T.; Miyahara, F.; Satoh, M.; Sievers, P.; Suwada, T.; Umemori, K.; Variola, A.

    2015-07-01

    Promising results obtained with crystal targets for positron production led to the elaboration of a hybrid source made of an axially oriented tungsten crystal, as a radiator, and an amorphous tungsten converter. If the converter is granular, made of small spheres, the heat dissipation is greatly enhanced and the thermal shocks reduced, allowing the consideration of such device for the future linear colliders. A positron source of this kind is investigated. Previous simulations have shown very promising results for the yield as for the energy deposition and the PEDD (Peak Energy Deposition Density). Here, we present detailed simulations made in this granular converter with emphasis on the energy deposition density, which is a critical parameter as learned from the breakdown of the SLC target. A test on the KEKB linac is foreseen; it will allow a determination of the energy deposited and the PEDD in the converter through temperature measurements. Four granular converters, made of W spheres of mm radius have been built at LAL-Orsay; they will be installed at KEK and compared to compact converters. A description of the experimental layout at KEK is provided. Applications to future linear colliders as CLIC and ILC are considered.

  14. MatrixConverter: Facilitating construction of phenomic character matrices1

    PubMed Central

    Liu, Jing; Endara, Lorena; Burleigh, J. Gordon

    2015-01-01

    • Premise of the study: While numerous software packages enable scientists to evaluate molecular data and transform them for phylogenetic analyses, few such tools exist for phenomic data. We introduce MatrixConverter, a program that helps expedite and facilitate the transformation of raw phenomic character data into discrete character matrices that can be used in most evolutionary inference programs. • Methods and Results: MatrixConverter is an open source program written in Java; a platform-independent binary executable, as well as sample data sets and a user’s manual, are available at https://github.com/gburleigh/MatrixConverter/tree/master/distribution. MatrixConverter has a simple, intuitive user interface that enables the user to immediately begin scoring phenomic characters. We demonstrate the performance of MatrixConverter on a phenomic data set from cycads. • Conclusions: New technologies and software make it possible to obtain phenomic data from species across the tree of life, and MatrixConverter helps to transform these new data for evolutionary or ecological inference. PMID:25699217

  15. Hybrid thermionic-photovoltaic converter

    NASA Astrophysics Data System (ADS)

    Datas, A.

    2016-04-01

    A conceptual device for the direct conversion of heat into electricity is presented. This concept hybridizes thermionic (TI) and thermophotovoltaic (TPV) energy conversion in a single thermionic-photovoltaic (TIPV) solid-state device. This device transforms into electricity both the electron and photon fluxes emitted by an incandescent surface. This letter presents an idealized analysis of this device in order to determine its theoretical potential. According to this analysis, the key advantage of this converter, with respect to either TPV or TI, is the higher power density in an extended temperature range. For low temperatures, TIPV performs like TPV due to the negligible electron flux. On the contrary, for high temperatures, TIPV performs like TI due to the great enhancement of the electron flux, which overshadows the photon flux contribution. At the intermediate temperatures, ˜1650 K in the case of this particular study, I show that the power density potential of TIPV converter is twice as great as that of TPV and TI. The greatest impact concerns applications in which the temperature varies in a relatively wide range, for which averaged power density enhancement above 500% is attainable.

  16. A dc to dc converter

    NASA Technical Reports Server (NTRS)

    Willis, A. E.; Gould, J. M.; Matheney, J. L.; Garrett, H. (Inventor)

    1984-01-01

    The object of the invention is to provide an improved converter for converting one direct current voltage to another. A plurality of phased square wave voltages are provided from a ring counter through amplifiers to a like plurality of output transformers. Each of these transformers has two windings, and S(1) winding and an S(2) winding. The S(1) windings are connected in series, then the S(2) windings are connected in series, and finally, the two sets of windings are connected in series. One of six SCRs is connected between each two series connected windings to a positive output terminal and one of diodes is connected between each set of two windings of a zero output terminal. By virtue of this configuration, a quite high average direct current voltage is obtained, which varies between full voltage and two-thirds full voltage rather than from full voltage to zero. Further, its variation, ripple frequency, is reduced to one-sixth of that present in a single phase system. Application to raising battery voltage for an ion propulsion system is mentioned.

  17. Advanced byproduct recovery: Direct catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly report, April 1--June 30, 1997

    SciTech Connect

    1997-12-31

    The team of Arthur D. Little, Tufts University and Engelhard Corporation are conducting Phase 1 of a four and a half year, two-phase effort to develop and scale-up an advanced byproduct recovery technology that is a direct, single-stage, catalytic process for converting sulfur dioxide to elemental sulfur. This catalytic process reduces SO{sub 2} over a fluorite-type oxide (such as ceria and zirconia). The catalytic activity can be significantly promoted by active transition metals, such as copper. More than 95% elemental sulfur yield, corresponding to almost complete sulfur dioxide conversion, was obtained over a Cu-Ce-O oxide catalyst as part of an on-going DOE-sponsored, University Coal Research Program. This type of mixed metal oxide catalyst has stable activity, high selectivity for sulfur production, and is resistant to water and carbon dioxide poisoning. Tests with CO and CH{sub 4} reducing gases indicate that the catalyst has the potential for flexibility with regard to the composition of the reducing gas, making it attractive for utility use. The performance of the catalyst is consistently good over a range of SO{sub 2} inlet concentration (0.1 to 10%) indicating its flexibility in treating SO{sub 2} tail gases as well as high concentration streams. The principal objective of the Phase 1 program is to identify and evaluate the performance of a catalyst which is robust and flexible with regard to choice of reducing gas. In order to achieve this goal, the authors have planned a structured program including: Market/process/cost/evaluation; Lab-scale catalyst preparation/optimization studies; Lab-scale, bulk/supported catalyst kinetic studies; Bench-scale catalyst/process studies; and Utility review. Progress is reported from all three organizations.

  18. Catalytic combustion with steam injection

    NASA Technical Reports Server (NTRS)

    Anderson, D. N.; Tacina, R. R.

    1982-01-01

    The effects of steam injection on (1) catalytic combustion performance, and (2) the tendency of residual fuel to burn in the premixing duct upstream of the catalytic reactor were determined. A petroleum residual, no. 2 diesel, and a blend of middle and heavy distillate coal derived fuels were tested. Fuel and steam were injected together into the preheated airflow entering a 12 cm diameter catalytic combustion test section. The inlet air velocity and pressure were constant at 10 m/s and 600 kPa, respectively. Steam flow rates were varied from 24 percent to 52 percent of the air flow rate. The resulting steam air mixture temperatures varied from 630 to 740 K. Combustion temperatures were in the range of 1200 to 1400 K. The steam had little effect on combustion efficiency or emissions. It was concluded that the steam acts as a diluent which has no adverse effect on catalytic combustion performance for no. 2 diesel and coal derived liquid fuels. Tests with the residual fuel showed that upstream burning could be eliminated with steam injection rates greater than 30 percent of the air flow rate, but inlet mixture temperatures were too low to permit stable catalytic combustion of this fuel.

  19. Angiotensin-converting enzyme inhibitory effects by plant phenolic compounds: a study of structure activity relationships.

    PubMed

    Al Shukor, Nadin; Van Camp, John; Gonzales, Gerard Bryan; Staljanssens, Dorien; Struijs, Karin; Zotti, Moises J; Raes, Katleen; Smagghe, Guy

    2013-12-01

    In this study, 22 phenolic compounds were investigated to inhibit the angiotensin-converting enzyme (ACE). Tannic acid showed the highest activity (IC50 = 230 μM). The IC50 values obtained for phenolic acids and flavonoids ranged between 0.41 and 9.3 mM. QSAR analysis confirmed that the numbers of hydroxyl groups on the benzene ring play an important role for activity of phenolic compounds and that substitution of hydroxyl groups by methoxy groups decreased activity. Docking studies indicated that phenolic acids and flavonoids inhibit ACE via interaction with the zinc ion and this interaction is stabilized by other interactions with amino acids in the active site. Other compounds, such as resveratrol and pyrogallol, may inhibit ACE via interactions with amino acids at the active site, thereby blocking the catalytic activity of ACE. These structure-function relationships are useful for designing new ACE inhibitors and potential blood-pressure-lowering compounds based on phenolic compounds. PMID:24219111

  20. Forback DC-to-DC converter

    NASA Technical Reports Server (NTRS)

    Lukemire, Alan T. (Inventor)

    1995-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  1. Data Converters Performance at Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    Rejeshuni, Rarnesham; Kumar, Nikil; Mao, James; Keymeulen, Didier; Zebulum, Ricardo S.; Stoica, Adrian

    2006-01-01

    Space missions often require radiation and extreme-temperature hardened electronics to survive the harsh environments beyond earth's atmosphere. Traditional approaches to preserve electronics incorporate shielding, insulation and redundancy at the expense of power and weight. However, a novel way of bypassing these problems is the concept of evolutionary hardware. A reconfgurable device, consisting of several switches interconnected with analog/digital parts, is controlled by an evolutionary processor (EP). When the EP detects degradation in the circuit it sends signals to reconfgure the switches, thus forming a new circuit with the desired output. This concept has been developed since the mid-90s, but one problem remains - the EP cannot degrade substantially. For this reason, extensive testing at extreme temperatures (-180' to 120(deg)C) has been done on devices found on FPGA boards (taking the role of the EP) such as the Analog to Digital and the Digital to Analog Converter. Analysis of the results has shown that FPGA boards implementing EP with some compensation may be a practical solution to evolving circuits. This paper describes results on the tests of data converters at extreme temperatures.

  2. Forback DC-to-DC converter

    NASA Technical Reports Server (NTRS)

    Lukemire, Alan T. (Inventor)

    1993-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  3. Poisoning of bubble propelled catalytic micromotors: the chemical environment matters.

    PubMed

    Zhao, Guanjia; Sanchez, Samuel; Schmidt, Oliver G; Pumera, Martin

    2013-04-01

    Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing -SH, -SSR, and -SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered. PMID:23450281

  4. Poisoning of bubble propelled catalytic micromotors: the chemical environment matters

    PubMed Central

    Zhao, Guanjia; Sanchez, Samuel; Schmidt, Oliver G.

    2013-01-01

    Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing –SH, –SSR, and –SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered. PMID:23450281

  5. Poisoning of bubble propelled catalytic micromotors: the chemical environment matters

    NASA Astrophysics Data System (ADS)

    Zhao, Guanjia; Sanchez, Samuel; Schmidt, Oliver G.; Pumera, Martin

    2013-03-01

    Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing -SH, -SSR, and -SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered.

  6. Photovoltaic converters for solar-pumped lasers

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Heinbockel, John H.

    1988-01-01

    The authors describe a mathematical parametric study of converters used to convert laser radiation to electricity for space-based laser power systems. Two different lasers, the 1.06-micron Nd laser and the 1.315-micron iodine laser, are used in the vertical junction converter. The calculated efficiency is 50 percent for a 100-junction Si photovoltaic converter when used with a Nd laser. The calculated efficiency for a 1000-junction Ga(0.53)In(0.47)As photovoltaic converter is 43 percent when used with an iodine laser.

  7. Thermoelectric converters for alternating current standards

    NASA Astrophysics Data System (ADS)

    Anatychuk, L. I.; Taschuk, D. D.

    2012-06-01

    Thermoelectric converters of alternating current remain priority instruments when creating standard equipment. This work presents the results of design and manufacture of alternating current converter for a military standard of alternating current in Ukraine. Results of simulation of temperature distribution in converter elements, ways of optimization to improve the accuracy of alternating current signal reproduction are presented. Results of metrological trials are given. The quality of thermoelectric material specially created for alternating current metrology is verified. The converter was used in alternating current standard for the frequency range from 10 Hz to 30 MHz. The efficiency of using thermoelectric signal converters in measuring instruments is confirmed.

  8. Microlith-Based Catalytic Reactor for Air Quality and Trace Contaminant Control Applications

    NASA Technical Reports Server (NTRS)

    Vilekar, Saurabh; Hawley, Kyle; Junaedi, Christian; Crowder, Bruce; Prada, Julian; Mastanduno, Richard; Perry, Jay L.; Kayatin, Matthew J.

    2015-01-01

    Traditionally, gaseous compounds such as methane, carbon monoxide, and trace contaminants have posed challenges for maintaining clean air in enclosed spaces such as crewed spacecraft cabins as they are hazardous to humans and are often difficult to remove by conventional adsorption technology. Catalytic oxidizers have provided a reliable and robust means of disposing of even trace levels of these compounds by converting them into carbon dioxide and water. Precision Combustion, Inc. (PCI) and NASA - Marshall (MSFC) have been developing, characterizing, and optimizing high temperature catalytic oxidizers (HTCO) based on PCI's patented Microlith® technology to meet the requirements of future extended human spaceflight explorations. Current efforts have focused on integrating the HTCO unit with a compact, simple recuperative heat exchanger to reduce the overall system size and weight while also reducing its energy requirements. Previous efforts relied on external heat exchangers to recover the waste heat and recycle it to the oxidizer to minimize the system's power requirements; however, these units contribute weight and volume burdens to the overall system. They also result in excess heat loss due to the separation of the HTCO and the heat recuperator, resulting in lower overall efficiency. Improvements in the recuperative efficiency and close coupling of HTCO and heat recuperator lead to reductions in system energy requirements and startup time. Results from testing HTCO units integrated with heat recuperators at a variety of scales for cabin air quality control and heat melt compactor applications are reported and their benefits over previous iterations of the HTCO and heat recuperator assembly are quantified in this paper.

  9. Designing catalytic nanomotors by dynamic shadowing growth.

    PubMed

    He, Yuping; Wu, Jinsong; Zhao, Yiping

    2007-05-01

    Using a geometric shadowing effect, a thin catalyst layer can be coated asymmetrically on the side of a nanorod backbone. Combining with substrate rotation, a dynamic shadowing growth technique has been developed to fabricate catalytic nanomotors such as rotary Si/Pt nanorods, rotary L-shaped Si/Pt and Si/Ag nanorods, and rolling Si/Ag nanosprings, and their autonomous motions have been demonstrated in a diluted H2O2 solution. This fabrication method reveals an optimistic step toward designing integrated nanomachines. PMID:17430007

  10. Catalytic Enantioselective Synthesis of Quaternary Carbon Stereocenters

    PubMed Central

    Quasdorf, Kyle W.; Overman, Larry E.

    2015-01-01

    Preface Quaternary carbon stereocenters–carbon atoms to which four distinct carbon substituents are attached–are common features of molecules found in nature. However, prior to recent advances in chemical catalysis, there were few methods available for constructing single stereoisomers of this important structural motif. Here we discuss the many catalytic enantioselective reactions developed during the past decade for synthesizing organic molecules containing such carbon atoms. This progress now makes it possible to selectively incorporate quaternary stereocenters in many high-value organic molecules for use in medicine, agriculture, and other areas. PMID:25503231

  11. Thin film porous membranes for catalytic sensors

    SciTech Connect

    Hughes, R.C.; Boyle, T.J.; Gardner, T.J.

    1997-06-01

    This paper reports on new and surprising experimental data for catalytic film gas sensing resistors coated with nanoporous sol-gel films to impart selectivity and durability to the sensor structure. This work is the result of attempts to build selectivity and reactivity to the surface of a sensor by modifying it with a series of sol-gel layers. The initial sol-gel SiO{sub 2} layer applied to the sensor surprisingly showed enhanced O{sub 2} interaction with H{sub 2} and reduced susceptibility to poisons such as H{sub 2}S.

  12. Catalytic distillation water recovery subsystem

    NASA Technical Reports Server (NTRS)

    Budininkas, P.; Rasouli, F.

    1985-01-01

    An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine based on the vapor phase catalytic ammonia removal was designed, fabricated and tested. Unlike other evaporative methods, this process catalytically oxidizes ammonia and volatile hydrocarbons vaporizing with water to innocuous products; therefore, no pretreatment of urine is required. Since the subsystem is fabricated from commercially available components, its volume, weight and power requirements are not optimized; however, it is suitable for zero-g operation. The testing program consists of parametric tests, one month of daily tests and a continuous test of 168 hours duration. The recovered water is clear, odorless, low in ammonia and organic carbon, and requires only an adjustment of its pH to meet potable water standards. The obtained data indicate that the vapor phase catalytic ammonia removal process, if further developed, would also be competitive with other water recovery systems in weight, volume and power requirements.

  13. Design of Compact Multi-Megawatt Mode Converter

    SciTech Connect

    Dolgashev, V.A.; Tantawi, S.G.; Nantista, C.D.; /SLAC

    2006-03-21

    Experience gained during recent operation of high power 11.424 GHz rf sources for accelerators led to new, more strict requirements on system components. One of the basic components of such a system is a mode converter that transforms the rectangular waveguide mode into the TE{sub 01} mode in circular waveguide. With such a converter, it is possible to minimize the use of WR90 rectangular waveguide which was shown to be a weak part of the previous system at power levels higher than 100 MW and pulse lengths on the order of a microsecond. We used several methods to design a mode converter with extremely low parasitic mode conversion and compact size. These methods employ HFSS[4] and include multi-parameter searches, concurrent optimization with a mode-matching code Cascade[2], cascading of resulting S-matrices, and tolerance analysis using perturbation techniques. This report describes the design methods and presents results.

  14. Electrochemical fabrication of Cu(OH) 2 and CuO nanostructures and their catalytic property

    NASA Astrophysics Data System (ADS)

    Ming, Hai; Pan, Keming; Liu, Yang; Li, Haitao; He, Xiaodie; Ming, Jun; Ma, Zheng; Kang, Zhenhui

    2011-07-01

    In this paper, we reported an anodization method for the fabrication of novel uniform Cu(OH) 2 nanowires, CuO nanoparticles, and CuO shuttle-like nanoparticles with advanced structures. The possible formation mechanism of Cu(OH) 2 nanowires, CuO nanoparticles, and CuO shuttle-like nanoparticles was proposed. The good catalytic properties of CuO nanoparticles converted from Cu(OH) 2 nanowires and the CuO shuttle-like nanoparticles were confirmed by evaluating their catalytic ability on the C-N cross coupling of amines with iodobenzene.

  15. Dielectric heating catalytic converter system for reducing cold-start emissions

    SciTech Connect

    Takatsu, Katsumi; Kurogi, Fumiyasu; Matsue, Akihiro; Kasaya, Masashi

    1996-09-01

    To reduce the harmful pollutants in cold start emissions, this study has been considering microwave dielectric technique for rapid catalyst heating. A dielectric material, having a relatively large loss factor at 2.45GHz was selected. This was coated to the exhaust catalyst allowing microwave energy to be deposited efficiently. The developed system has been tested successfully using a single-mode cavity in conjunction with a model gas. Moreover, a concept for practical in-vehicle system using the microwave heated catalyst has been proposed.

  16. New tests for characterizing the durability of a ceramic catalytic converter package

    SciTech Connect

    Reddy, K.P.; Helfinstine, J.D.; Gulati, S.T.

    1996-09-01

    New test methods were developed to characterize the high temperature durability of intumescent mats that are used to mount ceramic catalyst supports in stainless steel cans. The key attribute of these tests is the use of an electric resistance heating method to maintain a temperature gradient through the thickness of the mat when a cyclic or constant shear stress is applied to the mat interface. These tests are simple to perform and do not require expensive equipment or highly skilled operators. Using these new test methods, the durability of ceramic preconverters mounted with 4,070 gm/m{sup 2} intumescent mat was studied. The results of these tests indicate that a preconverter package with 4070 gm/m{sup 2} intumescent mat can perform satisfactorily in the close-coupled application where temperatures exceed 900 C. The mat performance can be quantified in terms of applied stress and test temperature by utilizing the experimental methods described in the present study.

  17. Effectiveness of replacing catalytic converters in LPG-fueled vehicles in Hong Kong

    NASA Astrophysics Data System (ADS)

    Lyu, X. P.; Guo, H.; Simpson, I. J.; Meinardi, S.; Louie, P. K. K.; Ling, Z. H.; Wang, Y.; Liu, M.; Luk, C. W. Y.; Wang, N.; Blake, D. R.

    2015-12-01

    Many taxis and public buses are powered by liquefied petroleum gas (LPG) in Hong Kong. With more vehicles using LPG, they have become the major contributor to ambient volatile organic compounds (VOCs) in Hong Kong. An intervention program aimed to reduce the emissions of VOCs and nitrogen oxides (NOx) from LPG-fueled vehicles was implemented by the Hong Kong Government in September 2013. Long-term real-time measurements indicated that the program was remarkably effective in reducing LPG-related VOCs, NOx and nitric oxide (NO) in the atmosphere. Receptor modeling results further revealed that propane, propene, i-butane, n-butane and NO in LPG-fueled vehicle exhaust emissions decreased by 37.3 ± 0.4, 50.2 ± 0.3, 32.9 ± 0.4, 41.1 ± 0.4 and 75.9 ± 0.3 %, respectively, during the implementation of the program. In contrast, despite the reduction of VOCs and NOx, the O3 production following the program increased by 0.25 ± 0.04 ppbv h-1 (4.8 %). Moreover, the production rate of HOx decreased due to the reduction of VOCs, whereas NO reduction resulted in a more significant decrease of the HOx in destruction compared to the decrease in production, and an increase of hydroxyl (OH) and hydroperoxyl (HO2). Analysis of O3-VOCs-NOx sensitivity in ambient air indicated VOC-limited regimes in the O3 formation before and during the program. Moreover, a maximum reduction percentage of NOx (i.e., 29.4 %) and the lowest reduction ratio of VOCs / NOx (i.e., ~ 3 : 1) in LPG-fueled vehicle emissions were determined to give a zero O3 increment. The findings are of great help to future formulation and implementation of control strategies on vehicle emissions in Hong Kong.

  18. Effectiveness of replacing catalytic converters in LPG-fueled vehicles in Hong Kong

    NASA Astrophysics Data System (ADS)

    Lyu, Xiaopu; Guo, Hai; Simpson, Isobel J.; Meinardi, Simone; Louie, Peter K. K.; Ling, Zhenhao; Wang, Yu; Liu, Ming; Luk, Connie W. Y.; Wang, Nan; Blake, Donald R.

    2016-05-01

    Many taxis and public buses are powered by liquefied petroleum gas (LPG) in Hong Kong. With more vehicles using LPG, they have become the major contributor to ambient volatile organic compounds (VOCs) in Hong Kong. An intervention program which aimed to reduce the emissions of VOCs and nitrogen oxides (NOx) from LPG-fueled vehicles was implemented by the Hong Kong government in September 2013. Long-term real-time measurements indicated that the program was remarkably effective in reducing LPG-related VOCs, NOx and nitric oxide (NO) in the atmosphere. Receptor modeling results further revealed that propane, propene, i-butane, n-butane and NO in LPG-fueled vehicle exhaust emissions decreased by 40.8 ± 0.1, 45.7 ± 0.2, 35.7 ± 0.1, 47.8 ± 0.1 and 88.6 ± 0.7 %, respectively, during the implementation of the program. In contrast, despite the reduction of VOCs and NOx, O3 following the program increased by 0.40 ± 0.03 ppbv (˜ 5.6 %). The LPG-fueled vehicle exhaust was generally destructive to OH and HO2. However, the destruction effect weakened for OH and it even turned to positive contribution to HO2 during the program. These changes led to the increases of OH, HO2 and HO2 / OH ratio, which might explain the positive O3 increment. Analysis of O3-VOCs-NOx sensitivity in ambient air indicated VOC-limited regimes in the O3 formation before and during the program. Moreover, a maximum reduction percentage of NOx (i.e., 69 %) and the lowest reduction ratio of VOCs / NOx (i.e., 1.1) in LPG-fueled vehicle exhaust were determined to give a zero O3 increment. The findings are of great help to future formulation and implementation of control strategies on vehicle emissions in Hong Kong, and could be extended to other regions in China and around the world.

  19. DNA replication: polymerase epsilon as a non-catalytic converter of the helicase.

    PubMed

    Zegerman, Philip

    2013-04-01

    In eukaryotes DNA polymerase epsilon (ε) synthesises the leading DNA strand during replication. A new study provides insight into how this polymerase also functions independently of its enzyme activity to assemble and activate the replicative helicase. PMID:23578873

  20. Preliminary Characterization of a Coaxial DBD Plasma-Catalytic Converter for Methane Partial Oxidation

    NASA Astrophysics Data System (ADS)

    Coulombe, Sylvain; Diaz Gomez Maqueo, Pablo; Evans, Mathew; Sainct, Florent; Bergthorson, Jeff

    2015-09-01

    This contribution discusses the development and characteristics of a coaxial dielectric barrier discharge (DBD) using a methane-oxygen mixture at atmospheric conditions of temperature and pressure. A sinusoidal voltage waveform of 12 kVp-p at 20 kHz produces discharges in a 1.15 mm gap. Power is estimated using a Lissajous figure method while optical emission spectroscopy (OES) is used to estimate the rotational and vibrational temperatures of the gas. Obtained OES spectra are similar, differing mainly on the intensity of their CH and OH bands, tending towards a more intense OH band as oxygen availability increased. CH bands show the strongest emission intensities of which, CH(C-X) seems to be the most intense of all, followed by CH(A-X) and lastly by CH(B-X). The spectra of CH(A-X) and CH(C-X) were uploaded into a simulation software to estimate the plasma temperatures. For the CH(A-X) bands, a simulation with a Trot = 600 K and a Tvib = 6000 K matched the experimental spectra. In the case of the CH(C-X) band, a Trot = 800 K and a Tvib = 4000 K were determined. The vibrational temperatures are especially high, a result which is particularly important for the development of a plasma-catalysis reactor. The authors acknowledge the financial support provided by NSERC, FRQNT as well as McGill University through the McGill Engineering Doctoral Award program.

  1. Catalytic Preparation of Pyrrolidones from Renewable Resources

    SciTech Connect

    Frye, John G.; Zacher, Alan H.; Werpy, Todd A.; Wang, Yong

    2005-12-01

    Use of renewable resources for production of valuable chemical commodities is becoming a topic of great national interest and importance. This objective fits well with the USDOE’s objective of promoting the industrial bio-refinery concept in which a wide array of valuable chemical, fuel, food, nutraceuticals and animal feed products all result from the integrated processing of grains, oil seeds and other bio-mass materials. The bio-refinery thus serves to enhance the overall utility and profitability of the agriculture industry as well as helping to reduce the dependence on petroleum. Pyrrolidones fit well with the bio-refinery concept since they may be produced in a scheme beginning with the fermentation of a portion of the bio-refinery’s sugar product into succinate. Pyrrolidones are a class of industrially important chemicals with a variety of uses including as polymer intermediates, cleaners, and “green solvents” which can replace hazardous chlorinated compounds. Battelle has developed an efficient process for the thermo – catalytic conversion of succinate into pyrrolidones, especially n-methylpyrrolidone. The process uses both novel Rh based catalysts and novel aqueous process conditions and results in high selectivities and yields of pyrrolidone compounds. The process also includes novel methodology for enhancing yields by recycling and converting non-useful side products of the catalysis into additional pyrrolidone. The process has been demonstrated in both batch and continuous reactors. Additionally, stability of the unique Rh-based catalyst has been demonstrated.

  2. Catalytic Enantioselective Carboannulation with Allylsilanes

    PubMed Central

    Ball-Jones, Nicolas R.; Badillo, Joseph J.; Tran, Ngon T.; Franz, Annaliese K.

    2015-01-01

    The first catalytic asymmetric carboannulation with allylsilanes is presented. The enantioselective [3+2] annulation is catalyzed using a Sc(III)-indapybox complex with tetrakis-[3,5-bis(trifluoromethyl)phenyl]-borate (BArF) to enhance catalytic activity and control stereoselectivity. Functionalized cyclopentanes containing a quaternary carbon are derived from alkylidene oxindole, coumarin, and malonate substrates with high stereoselectivity. The enantioselective 1,4-conjugate addition and enantioselective lactone formation (via trapping of the β-silyl carbocation) is also described. PMID:25045133

  3. Catalytic enantioselective carboannulation with allylsilanes.

    PubMed

    Ball-Jones, Nicolas R; Badillo, Joseph J; Tran, Ngon T; Franz, Annaliese K

    2014-09-01

    The first catalytic asymmetric carboannulation with allylsilanes is presented. The enantioselective [3+2] annulation is catalyzed using a scandium(III)/indapybox complex with tetrakis-[3,5-bis(trifluoromethyl)phenyl]-borate (BArF) to enhance catalytic activity and control stereoselectivity. Functionalized cyclopentanes containing a quaternary carbon center are derived from alkylidene oxindole, coumarin, and malonate substrates with high stereoselectivity. The enantioselective 1,4-conjugate addition and enantioselective lactone formation (by trapping of the β-silyl carbocation) is also described. PMID:25045133

  4. Perfluoropolyalkylether decomposition on catalytic aluminas

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo

    1994-01-01

    The decomposition of Fomblin Z25, a commercial perfluoropolyalkylether liquid lubricant, was studied using the Penn State Micro-oxidation Test, and a thermal gravimetric/differential scanning calorimetry unit. The micro-oxidation test was conducted using 440C stainless steel and pure iron metal catalyst specimens, whereas the thermal gravimetric/differential scanning calorimetry tests were conducted using catalytic alumina pellets. Analysis of the thermal data, high pressure liquid chromatography data, and x-ray photoelectron spectroscopy data support evidence that there are two different decomposition mechanisms for Fomblin Z25, and that reductive sites on the catalytic surfaces are responsible for the decomposition of Fomblin Z25.

  5. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a thermionic converter to support an end an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housng, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  6. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  7. Catalytic Stereoinversion of L-Alanine to Deuterated D-Alanine.

    PubMed

    Moozeh, Kimia; So, Soon Mog; Chin, Jik

    2015-08-01

    A combination of an achiral pyridoxal analogue and a chiral base has been developed for catalytic deuteration of L-alanine with inversion of stereochemistry to give deuterated D-alanine under mild conditions (neutral pD and 25 °C) without the use of any protecting groups. This system can also be used for catalytic deuteration of D-alanine with retention of stereochemistry to give deuterated D-alanine. Thus a racemic mixture of alanine can be catalytically deuterated to give an enantiomeric excess of deuterated D-alanine. While catalytic deracemization of alanine is forbidden by the second law of thermodynamics, this system can be used for catalytic deracemization of alanine with deuteration. Such green and biomimetic approach to catalytic stereocontrol provides insights into efficient amino acid transformations. PMID:26119066

  8. An abnormal N-heterocyclic carbene based nickel complex for catalytic reduction of nitroarenes.

    PubMed

    Vijaykumar, Gonela; Mandal, Swadhin K

    2016-05-01

    Herein we report the synthesis of a nickel(ii) dichloro complex bearing an abnormal N-heterocyclic carbene (aNHC). The NiCl2(aNHC)2 complex has been used as an efficient catalyst for the reduction of nitroarenes with hydrosilanes to give aromatic amines in good to excellent yields. This catalytic protocol can tolerate functional groups such as halides, alkenes or nitriles. Furthermore, the longevity of the catalyst was tested in successive catalytic cycles, which indicates a sustained catalytic activity over multiple catalytic cycles. PMID:27041677

  9. Olefin fractionation and catalytic conversion system with heat exchange means

    SciTech Connect

    Wright, B.S.; Owen, H.; Hsia, C.H

    1989-05-23

    This patent describes a continuous catalytic system for converting an olefinic feedstock comprising ethylene and C/sub 3/+ olefins to heavier liquid hydrocarbon product comprising: means for prefractionating the olefinic feedstock to obtain a gaseous stream rich in ethylene and a liquid stream containing C/sub 3/+ olefin; means for vaporizing and contacting the liquid stream from the prefractionating means with hydrocarbon conversion oligomerization catalyst in at least one exothermic catalytic reaction zone to provide a heavier hydrocarbon effluent stream comprising distillate, gasoline and lighter hydrocarbons; means for cooling and fractionating the effluent stream to recover distillate, gasoline and lighter hydrocarbons separately; means for recycling at least a portion of the recovered gasoline as a liquid sorbent stream to the prefractionating means thereby reacting the recycled gasoline together with sorbed C/sub 3/+ olefin in the catalytic reactor system; and means for exchanging heat between hot effluent from the exothermic reaction zone and fractionator liquid rich in C/sub 3/+ olefin in the prefractionator reboiler loop.

  10. CATALYTIC OXIDATION OF AIR POLLUTANTS FROM PULP AND PAPER INDUSTRY USING OZONE

    EPA Science Inventory

    Major pollutants from pulp and paper mills include volatile organic compounds (VOCs) such as methanol and total reduced sulfur compounds (TRS) such as dimethyl sulfide. The conventional treatment technologies including incineration or catalytic thermal oxidation are energy intens...

  11. Clustering of cycloidal wave energy converters

    DOEpatents

    Siegel, Stefan G.

    2016-03-29

    A wave energy conversion system uses a pair of wave energy converters (WECs) on respective active mountings on a floating platform, so that the separation of the WECs from each other or from a central WEC can be actively adjusted according to the wavelength of incident waves. The adjustable separation facilitates operation of the system to cancel reactive forces, which may be generated during wave energy conversion. Modules on which such pairs of WECs are mounted can be assembled with one or more central WECs to form large clusters in which reactive forces and torques can be made to cancel. WECs of different sizes can be employed to facilitate cancelation of reactive forces and torques.

  12. Simplifying the circuit of Josephson parametric converters

    NASA Astrophysics Data System (ADS)

    Abdo, Baleegh; Brink, Markus; Chavez-Garcia, Jose; Keefe, George

    Josephson parametric converters (JPCs) are quantum-limited three-wave mixing devices that can play various important roles in quantum information processing in the microwave domain, including amplification of quantum signals, transduction of quantum information, remote entanglement of qubits, nonreciprocal amplification, and circulation of signals. However, the input-output and biasing circuit of a state-of-the-art JPC consists of bulky components, i.e. two commercial off-chip broadband 180-degree hybrids, four phase-matched short coax cables, and one superconducting magnetic coil. Such bulky hardware significantly hinders the integration of JPCs in scalable quantum computing architectures. In my talk, I will present ideas on how to simplify the JPC circuit and show preliminary experimental results

  13. Catalyst for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The addition of an inert metal component, such as gold, silver or copper, to a Fischer-Tropsch catalyst comprising cobalt enables said catalyst to convert synthesis gas to liquid motor fuels at about 240.degree.-370.degree. C. with advantageously reduced selectivity of said cobalt for methane in said conversion. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  14. Converting a fuel to combustible gas

    SciTech Connect

    Moss, G.

    1985-04-02

    A sulfur-containing fuel is passed into a first fluidized bed containing CaSO/sub 4/ and CaO and an oxygen-transfer mediator (e.g. H/sub 2/) whereby the fuel is converted to combustible gas, some CaSO/sub 4/ being reduced to CaS and sulfur being fixed as CaS by reaction with CaO. Bed particles pass from the bottom layer of the first bed into the bottom layer of the second bed which is fluidized by air at conditions such that some, but not all of the CaS is selectively oxidized to CaSO/sub 4/ with no liberation of sulfur moieties. Bed particles pass from the bottom layer of second bed to the bottom layer of a third bed optionally after passage via a fourth bed between the second and third beds. In the third bed particles are fluidized with air to convert CaS selectively to CaSO/sub 4/ with no liberation of sulfur moiety whereby to raise the particles' temperature sufficiently above that of the first bed that particles passing from the bottom layer of the third bed into the bottom layer of the first bed provide sufficient sensible heat to maintain the fuel conversion temperature of the first bed. In the fourth bed particles are fluidized with air under such conditions that sulfur moiety is liberated, preferably at a rate which approximately equals the rate of sulfur-capture in the first bed whereby to maintain approximately a constant amount of reactive CaO in the beds for sulfur-capture in the first bed.

  15. Design optimization, manufacture and response measurements for fast-neutron radiography converters made of scintillator and wavelength-shifting fibers

    NASA Astrophysics Data System (ADS)

    Li, Hang; Wu, Yang; Cao, Chao; Huo, Heyong; Tang, Bin

    2014-10-01

    In order to improve the image quality of fast neutron radiography, a converter made of scintillator and wavelength-shifting fibers has been developed. The appropriate parameters of the converter such as fibers arrangement, distance between fibers are optimized theoretically, and manufacture of the converter are also optimized. Fast neutron radiography experiments by 14 MeV neutrons are used to test this converter and kinds of traditional converters. The experiments' results matched the calculations. The novel converter's resolution is better than 1 mm and the light output is high.

  16. Catalytically enhanced packed tower scrubbing

    SciTech Connect

    Stitt, E.H.; Taylor, F.J.; Kelly, K.

    1996-12-31

    An enhanced wet scrubbing process for the treatment of gas streams containing odours and low level VOC`s is presented. It comprises essentially a single scrubbing column and a fixed bed catalytic reactor through which the dilute alkaline bleach scrubbing liquor is recirculated. The process has significant cost advantages over conventional chemical scrubbing technology, and copes well with peaks in odour levels. Traditional bleach scrubbing, and the improvements in process chemistry and the flowsheet afforded by inclusion of the catalyst, are discussed. The catalyst enables many of the well known problems associated with bleach scrubbing to be overcome, and facilitates odour removal efficiencies of greater than 99% in a single column. Pilot plant data from trials on sewage treatment works are presented. These show clearly the ability of the catalytically enhanced process to achieve sulphide and odour removals in excess of 99% in the single column. Case studies of some of the existing commercial installations are given, indicating the wide range of applications, industries and scale of the installed units. Comparative data are presented, measured on a commercial unit for the conventional operation of a bleach scrubber, and with the retrofitted catalyst in use. These data show clearly the benefits of the catalytic process in terms of removal efficiencies; and hence by inference also in equipment size and costs. The catalytic process is also shown to achieve very high removal efficiencies of organo-sulphides in a single column. 8 refs., 3 figs., 10 tabs.

  17. CATALYTIC COMBUSTION COMPONENT AND SYSTEM PROTOTYPE DEVELOPMENT

    EPA Science Inventory

    The report gives results of a project to develop the components required for catalytic combustion system operation and evaluation. The systems investigated (firetube boiler, watertube boiler, and gas turbine), when integrated with the catalytic combustor, have potential for both ...

  18. MEMS-based fuel cells with integrated catalytic fuel processor and method thereof

    DOEpatents

    Jankowski, Alan F.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Havstad, Mark A.

    2011-08-09

    Described herein is a means to incorporate catalytic materials into the fuel flow field structures of MEMS-based fuel cells, which enable catalytic reforming of a hydrocarbon based fuel, such as methane, methanol, or butane. Methods of fabrication are also disclosed.

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

    SciTech Connect

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

    2011-05-28

    Biomass gasification is a flexible and efficient way of utilizing widely available domestic renewable resources. Syngas from biomass has the potential for biofuels production, which will enhance energy security and environmental benefits. Additionally, with the successful development of low Btu fuel engines (e.g. GE Jenbacher engines), syngas from biomass can be efficiently used for power/heat co-generation. However, biomass gasification has not been widely commercialized because of a number of technical/economic issues related to gasifier design and syngas cleanup. Biomass gasification, due to its scale limitation, cannot afford to use pure oxygen as the gasification agent that used in coal gasification. Because, it uses air instead of oxygen, the biomass gasification temperature is much lower than well-understood coal gasification. The low temperature leads to a lot of tar formation and the tar can gum up the downstream equipment. Thus, the biomass gasification tar removal is a critical technology challenge for all types of biomass gasifiers. This USDA/DOE funded program (award number: DE-FG36-O8GO18085) aims to develop an advanced catalytic tar conversion system that can economically and efficiently convert tar into useful light gases (such as syngas) for downstream fuel synthesis or power generation. This program has been executed by GE Global Research in Irvine, CA, in collaboration with Professor Lanny Schmidt's group at the University of Minnesota (UoMn). Biomass gasification produces a raw syngas stream containing H2, CO, CO2, H2O, CH4 and other hydrocarbons, tars, char, and ash. Tars are defined as organic compounds that are condensable at room temperature and are assumed to be largely aromatic. Downstream units in biomass gasification such as gas engine, turbine or fuel synthesis reactors require stringent control in syngas quality, especially tar content to avoid plugging (gum) of downstream equipment. Tar- and ash-free syngas streams are a critical

  20. Comparing Approaches to Converting Large High Schools into Smaller Units

    ERIC Educational Resources Information Center

    Levine, Thomas H

    2011-01-01

    Scholars and reformers in the United States have called for converting large high schools into smaller units to provide a more effective, personal, and culturally responsive education for all students. Current literature argues that such "conversion high schools" should break into fully autonomous small schools rather than more interdependent…

  1. Catalytic pyrolysis of automobile shredder residue

    SciTech Connect

    Arzoumanidis, G.G.; McIntosh, M.J.; Steffensen, E.J.

    1995-07-01

    In the United States, approximately 10 million automobiles are scrapped and shredded each year. The mixture of plastics and other materials remaining after recovery of the metals is known as Automobile Shredder Residue (ASR). In 1994, about 3.5 million tons of ASR was produced and disposed of in landfills. However, environmental, legislative, and economic considerations are forcing the industry to search for recycling or other alternatives to disposal. Numerous studies have been done relating the ASR disposal problem to possible recycling treatments such as pyrolysis, gasification, co-liquefaction of ASR with coal, chemical recovery of plastics from ASR, catalytic pyrolysis, reclamation in molten salts, and vacuum pyrolysis. These and other possibilities have been studied intensively, and entire symposia have been devoted to the problem. Product mix, yields, toxicology issues, and projected economics of conceptual plant designs based on experimental results are among the key elements of past studies. Because the kinds of recycling methods that may be developed, along with their ultimate economic value, depend on a very large number of variables, these studies have been open-ended. It is hoped that it may be useful to explore some of these previously studied areas from fresh perspectives. One such approach, currently under development at Argonne National Laboratory, is the catalytic pyrolysis of ASR.

  2. Computational and Physical Analysis of Catalytic Compounds

    NASA Astrophysics Data System (ADS)

    Wu, Richard; Sohn, Jung Jae; Kyung, Richard

    2015-03-01

    Nanoparticles exhibit unique physical and chemical properties depending on their geometrical properties. For this reason, synthesis of nanoparticles with controlled shape and size is important to use their unique properties. Catalyst supports are usually made of high-surface-area porous oxides or carbon nanomaterials. These support materials stabilize metal catalysts against sintering at high reaction temperatures. Many studies have demonstrated large enhancements of catalytic behavior due to the role of the oxide-metal interface. In this paper, the catalyzing ability of supported nano metal oxides, such as silicon oxide and titanium oxide compounds as catalysts have been analyzed using computational chemistry method. Computational programs such as Gamess and Chemcraft has been used in an effort to compute the efficiencies of catalytic compounds, and bonding energy changes during the optimization convergence. The result illustrates how the metal oxides stabilize and the steps that it takes. The graph of the energy computation step(N) versus energy(kcal/mol) curve shows that the energy of the titania converges faster at the 7th iteration calculation, whereas the silica converges at the 9th iteration calculation.

  3. Determining Catalytic Cycles in the Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    Stock, Joachim; Boxe, Christopher; Grenfell, Lee; Lehmann, Ralph; Patzer, Beate; Rauer, Heike; Yung, Yuk

    2010-05-01

    Chemical trace species play an important role in the chemical composition of terrestrial planetary atmospheres. These species can operate in catalytic cycles, which critically affect the concentrations of major chemical constituents and hence the whole structure of the atmosphere itself. The determination of chemical pathways in such complex systems is generally a challenging task, so effective methods are desirable for the investigation of such problems. In order to address this question to the chemical catalytic cycles in the atmosphere of Mars, we use a new analysis tool (Pathway Analysis Program - PAP), which was originally developed and applied to automatically identify and quantify ozone and methane cycles in Earth's stratosphere. The implemented algorithm determines and quantifies all significant pathways by treating each species one after the other as a branching point. Pathways are formed by connecting shorter pathways producing those branching point species with pathways consuming them. Reaction rates are assigned to the pathways proportional to the branching probabilities. In order to identify and analyze the dominant chemical processes in the Martian atmosphere, we apply PAP to the CalTech photochemical column model. The methodology of the algorithm is presented and first results of our analysis are discussed in view of the relevant chemical trace species.

  4. Process for converting cellulosic materials into fuels and chemicals

    DOEpatents

    Scott, Charles D.; Faison, Brendlyn D.; Davison, Brian H.; Woodward, Jonathan

    1994-01-01

    A process for converting cellulosic materials, such as waste paper, into fuels and chemicals utilizing enzymatic hydrolysis of the major constituent of paper, cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. The cellulase is produced from a continuous, columnar, fluidized-bed bioreactor utilizing immobilized microorganisms. An attritor and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. The cellulase is recycled by an adsorption process. The resulting crude sugars are converted to dilute product in a fluidized-bed bioreactor utilizing microorganisms. The dilute product is concentrated and purified by utilizing distillation and/or a biparticle fluidized-bed bioreactor system.

  5. Catalytic gasification of bagasse for the production of methanol

    SciTech Connect

    Baker, E.G.; Brown, M.D.; Robertus, R.J.

    1985-10-01

    The purpose of the study was to evaluate the technical and economic feasibility of catalytic gasification of bagasse to produce methanol. In previous studies, a catalytic steam gasification process was developed which converted wood to methanol synthesis gas in one step using nickel based catalysts in a fluid-bed gasifier. Tests in a nominal 1 ton/day process development unit (PDU) gasifier with these same catalysts showed bagasse to be a good feedstock for fluid-bed gasifiers, but the catalysts deactivated quite rapidly in the presence of bagasse. Laboratory catalyst screening tests showed K/sub 2/CO/sub 3/ doped on the bagasse to be a promising catalyst for converting bagasse to methanol synthesis gas. PDU tests with 10 wt % K/sub 2/CO/sub 3/ doped on bagasse showed the technical feasibility of this type of catalyst on a larger scale. A high quality synthesis gas was produced and carbon conversion to gas was high. The gasifier was successfully operated without forming agglomerates of catalyst, ash, and char in the gasifier. There was no loss of activity throughout the runs because catalysts is continually added with the bagasse. Laboratory tests showed about 80% of the potassium carbonate could be recovered and recycled with a simple water wash. An economic evaluation of the process for converting bagasse to methanol showed the required selling price of methanol to be significantly higher than the current market price of methanol. Several factors make this current evaluaton using bagasse as a feedstock less favorable: (1) capital costs are higher due to inflation and some extra costs required to use bagasse, (2) smaller plant sizes were considered so economies of scale are lost, and (3) the market price of methanol in the US has fallen 44% in the last six months. 24 refs., 14 figs., 16 tabs.

  6. Radiation-Tolerant DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Skutt, Glenn; Sable, Dan; Leslie, Leonard; Graham, Shawn

    2012-01-01

    A document discusses power converters suitable for space use that meet the DSCC MIL-PRF-38534 Appendix G radiation hardness level P classification. A method for qualifying commercially produced electronic parts for DC-DC converters per the Defense Supply Center Columbus (DSCC) radiation hardened assurance requirements was developed. Development and compliance testing of standard hybrid converters suitable for space use were completed for missions with total dose radiation requirements of up to 30 kRad. This innovation provides the same overall performance as standard hybrid converters, but includes assurance of radiation- tolerant design through components and design compliance testing. This availability of design-certified radiation-tolerant converters can significantly reduce total cost and delivery time for power converters for space applications that fit the appropriate DSCC classification (30 kRad).

  7. Fuel Flexible, Low Emission Catalytic Combustor for Opportunity Fuel Applications

    SciTech Connect

    Eteman, Shahrokh

    2013-06-30

    Limited fuel resources, increasing energy demand and stringent emission regulations are drivers to evaluate process off-gases or process waste streams as fuels for power generation. Often these process waste streams have low energy content and/or highly reactive components. Operability of low energy content fuels in gas turbines leads to issues such as unstable and incomplete combustion. On the other hand, fuels containing higher-order hydrocarbons lead to flashback and auto-ignition issues. Due to above reasons, these fuels cannot be used directly without modifications or efficiency penalties in gas turbine engines. To enable the use of these wide variety of fuels in gas turbine engines a rich catalytic lean burn (RCL®) combustion system was developed and tested in a subscale high pressure (10 atm.) rig. The RCL® injector provided stability and extended turndown to low Btu fuels due to catalytic pre-reaction. Previous work has shown promise with fuels such as blast furnace gas (BFG) with LHV of 85 Btu/ft3 successfully combusted. This program extends on this work by further modifying the combustor to achieve greater catalytic stability enhancement. Fuels containing low energy content such as weak natural gas with a Lower Heating Value (LHV) of 6.5 MJ/m3 (180 Btu/ft3 to natural gas fuels containing higher hydrocarbon (e.g ethane) with LHV of 37.6 MJ/m3 (1010 Btu/ft3) were demonstrated with improved combustion stability; an extended turndown (defined as the difference between catalytic and non-catalytic lean blow out) of greater than 250oF was achieved with CO and NOx emissions lower than 5 ppm corrected to 15% O2. In addition, for highly reactive fuels the catalytic region preferentially pre-reacted the higher order hydrocarbons with no events of flashback or auto-ignition allowing a stable and safe operation with low NOx and CO emissions.

  8. Silicon waveguide based TE mode converter.

    PubMed

    Zhang, Jing; Liow, Tsung-Yang; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee

    2010-11-22

    A silicon waveguide based TE mode converter was designed for the mode conversion between a horizontal waveguide and vertical waveguide in the two-layer structure waveguide based polarization diversity circuit. The TE mode converter's performance was studied. The polarization mode converter with minimum length of 5 μm was demonstrated to provide the TE mode conversion while maintaining the polarization status. The insertion loss at the transition region was less than 2 dB. PMID:21164874

  9. Ocean floor mounting of wave energy converters

    SciTech Connect

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  10. Catalytic Activities Of [GADV]-Peptides

    NASA Astrophysics Data System (ADS)

    Oba, Takae; Fukushima, Jun; Maruyama, Masako; Iwamoto, Ryoko; Ikehara, Kenji

    2005-10-01

    We have previously postulated a novel hypothesis for the origin of life, assuming that life on the earth originated from “[GADV]-protein world”, not from the “RNA world” (see Ikehara's review, 2002). The [GADV]-protein world is constituted from peptides and proteins with random sequences of four amino acids (glycine [G], alanine [A], aspartic acid [D] and valine [V]), which accumulated by pseudo-replication of the [GADV]-proteins. To obtain evidence for the hypothesis, we produced [GADV]-peptides by repeated heat-drying of the amino acids for 30 cycles ([GADV]-P30) and examined whether the peptides have some catalytic activities or not. From the results, it was found that the [GADV]-P30 can hydrolyze several kinds of chemical bonds in molecules, such as umbelliferyl-β-D-galactoside, glycine-p-nitroanilide and bovine serum albumin. This suggests that [GADV]-P30 could play an important role in the accumulation of [GADV]-proteins through pseudo-replication, leading to the emergence of life. We further show that [GADV]-octapaptides with random sequences, but containing no cyclic compounds as diketepiperazines, have catalytic activity, hydrolyzing peptide bonds in a natural protein, bovine serum albumin. The catalytic activity of the octapeptides was much higher than the [GADV]-P30 produced through repeated heat-drying treatments. These results also support the [GADV]-protein-world hypothesis of the origin of life (see Ikehara's review, 2002). Possible steps for the emergence of life on the primitive earth are presented.

  11. Evaluation of High Performance Converters Under Low Dose Rate Total Ionizing Dose (TID) Testing for NASA Programs

    NASA Technical Reports Server (NTRS)

    Sharma, Ashok K.; Sahu, Kusum

    1998-01-01

    This paper reports the results of low dose rate (0.01-0.18 rads(Si)/sec) total ionizing dose (TID) tests performed on several types of high performance converters. The parts used in this evaluation represented devices such as a high speed flash converter, a 16-bit ADC and a voltage-to-frequency converter.

  12. Combustor design tool for a gas fired thermophotovoltaic energy converter

    SciTech Connect

    Lindler, K.W.; Harper, M.J.

    1995-07-01

    Recently, there has been a renewed interest in thermophotovoltaic (TPV) energy conversion. A TPV device converts radiant energy from a high temperature incandescent emitter directly into electricity by photovoltaic cells. The current Department of Energy sponsored research involves the design, construction and demonstration of a prototype TPV converter that uses a hydrocarbon fuel (such as natural gas) as the energy source. As the photovoltaic cells are designed to efficiently convert radiant energy at a prescribed wavelength, it is important that the temperature of the emitter be nearly constant over its entire surface. The US Naval Academy has been tasked with the development of a small emitter (with a high emissivity) that can be maintained at 1,756 K (2,700 F). This paper describes the computer spreadsheet model that was developed as a tool to be used for the design of the high temperature emitter.

  13. Combustor design tool for a gas fired thermophotovoltaic energy converter

    SciTech Connect

    Lindler, K.W.; Harper, M.J.

    1995-12-31

    Recently, there has been a renewed interest in thermophotovoltaic (TPV) energy conversion. A TPV device converts radiant energy from a high temperature incandescent emitter directly into electricity by photovoltaic cells. The current Department of Energy sponsored research involves the design, construction and demonstration of a prototype TPV converter that uses a hydrocarbon fuel (such as natural gas) as the energy source. As the photovoltaic cells are designed to efficiently convert radiant energy at a prescribed wavelength, it is important that the temperature of the emitter be nearly constant over its entire surface. The U. S. Naval Academy has been tasked with the development of a small emitter (with a high emissivity) that can be maintained at 1756 K (2700 F). This paper describes the computer spreadsheet model that was developed as a tool to be used for the design of the high temperature emitter.

  14. Power line carrier interference from HVDC converter terminals

    SciTech Connect

    Tatro, P.J.; Adamson, K.A. ); Eitzmann, M.A.; Smead, M. . Power Systems Engineering Dept.)

    1993-07-01

    Power line carrier (PLC) equipment typically operates in the frequency range from 25 kHz to 300 kHz. Interference studies for HVDC converters usually concentrate on interference from noise sources within this frequency range. However, operating experience at the Sandy Pond converter terminal has indicated that PLC equipment is also susceptible to interference from sources of power system harmonics below the PLC frequency range. Extensive field testing and analytical studies have shown that each PLC circuit has a resonant frequency below the operating frequency. If excited at this resonant frequency, high voltages may exist within the PLC circuit. The resulting saturation of PLC components leads to local generation of radio frequency (RF) noise that interferes with proper operation of PLC circuits. Sources of power system harmonics in the 3-10 kHz range, such as line commutated dc converters, are potential sources of this type of interference.

  15. A closely regulated TWT converter.

    NASA Technical Reports Server (NTRS)

    Hopper, D. J.; Andryczyk, R. W.

    1971-01-01

    The design concept for the TWT amplifier converter for possible use in the Thermoelectric Outer Planet Spacecraft (TOPS) is presented. An unusual combination of semiconductors and magnetics was utilized to achieve very stable voltage regulation on a number of separate outputs to satisfy the requirements of a high-power TWT, and at the same time operate at an efficiency of better than 90% from a 30-V source. The circuitry consists of an output filter, an auxiliary Jensen oscillator driving a high-reactance transformer to provide current limiting to the heater, a variable time delay, a main Jensen oscillator driving the power transformer with a maximum step-up ratio of 120 to 1, and series transistorized post regulators to provide precise voltage adjustment and low output impedance. This paper discusses the design of the high-reactance transformer and the high step-up ratio transformer, as well as the high-voltage series regulators that are limited in range and operate at the top of the unregulated output voltage. Test data are presented, and details of current transients caused by charging the filter circuits, input current ripple, and output voltage ripples are considered.

  16. DC/DC Converter Stability Testing Study

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2008-01-01

    This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

  17. Incorporation of catalytic dehydrogenation into fischer-tropsch synthesis to significantly reduce carbon dioxide emissions

    DOEpatents

    Huffman, Gerald P.

    2012-11-13

    A new method of producing liquid transportation fuels from coal and other hydrocarbons that significantly reduces carbon dioxide emissions by combining Fischer-Tropsch synthesis with catalytic dehydrogenation is claimed. Catalytic dehydrogenation (CDH) of the gaseous products (C1-C4) of Fischer-Tropsch synthesis (FTS) can produce large quantities of hydrogen while converting the carbon to multi-walled carbon nanotubes (MWCNT). Incorporation of CDH into a FTS-CDH plant converting coal to liquid fuels can eliminate all or most of the CO.sub.2 emissions from the water-gas shift (WGS) reaction that is currently used to elevate the H.sub.2 level of coal-derived syngas for FTS. Additionally, the FTS-CDH process saves large amounts of water used by the WGS reaction and produces a valuable by-product, MWCNT.

  18. Modular Power Converters for PV Applications

    SciTech Connect

    Ozpineci, Burak; Tolbert, Leon M

    2012-05-01

    This report describes technical opportunities to serve as parts of a technological roadmap for Shoals Technologies Group in power electronics for PV applications. There are many different power converter circuits that can be used for solar inverter applications. The present applications do not take advantage of the potential for using common modules. We envision that the development of a power electronics module could enable higher reliability by being durable and flexible. Modules would have fault current limiting features and detection circuits such that they can limit the current through the module from external faults and can identify and isolate internal faults such that the remaining modules can continue to operate with only minimal disturbance to the utility or customer. Development of a reliable, efficient, low-cost, power electronics module will be a key enabling technology for harnessing more power from solar panels and enable plug and play operation. Power electronics for computer power supplies, communication equipment, and transportation have all targeted reliability and modularity as key requirements and have begun concerted efforts to replace monolithic components with collections of common smart modules. This is happening on several levels including (1) device level with intelligent control, (2) functional module level, and (3) system module. This same effort is needed in power electronics for solar applications. Development of modular units will result in standard power electronic converters that will have a lower installed and operating cost for the overall system. These units will lead to increased adaptability and flexibility of solar inverters. Incorporating autonomous fault current limiting and reconfiguration capabilities into the modules and having redundant modules will lead to a durable converter that can withstand the rigors of solar power generation for more than 30 years. Our vision for the technology roadmap is that there is no need

  19. Target-directed catalytic metallodrugs

    PubMed Central

    Joyner, J.C.; Cowan, J.A.

    2013-01-01

    Most drugs function by binding reversibly to specific biological targets, and therapeutic effects generally require saturation of these targets. One means of decreasing required drug concentrations is incorporation of reactive metal centers that elicit irreversible modification of targets. A common approach has been the design of artificial proteases/nucleases containing metal centers capable of hydrolyzing targeted proteins or nucleic acids. However, these hydrolytic catalysts typically provide relatively low rate constants for target inactivation. Recently, various catalysts were synthesized that use oxidative mechanisms to selectively cleave/inactivate therapeutic targets, including HIV RRE RNA or angiotensin converting enzyme (ACE). These oxidative mechanisms, which typically involve reactive oxygen species (ROS), provide access to comparatively high rate constants for target inactivation. Target-binding affinity, co-reactant selectivity, reduction potential, coordination unsaturation, ROS products (metal-associated vs metal-dissociated; hydroxyl vs superoxide), and multiple-turnover redox chemistry were studied for each catalyst, and these parameters were related to the efficiency, selectivity, and mechanism(s) of inactivation/cleavage of the corresponding target for each catalyst. Important factors for future oxidative catalyst development are 1) positioning of catalyst reduction potential and redox reactivity to match the physiological environment of use, 2) maintenance of catalyst stability by use of chelates with either high denticity or other means of stabilization, such as the square planar geometric stabilization of Ni- and Cu-ATCUN complexes, 3) optimal rate of inactivation of targets relative to the rate of generation of diffusible ROS, 4) targeting and linker domains that afford better control of catalyst orientation, and 5) general bio-availability and drug delivery requirements. PMID:23828584

  20. Biofuel production from catalytic cracking of woody oils.

    PubMed

    Xu, Junming; Jiang, Jianchun; Chen, Jie; Sun, Yunjuan

    2010-07-01

    The catalytic cracking reactions of several kinds of woody oils have been studied. The products were analyzed by GC-MS and FTIR and show the formation of olefins, paraffins and carboxylic acids. Several kinds of catalysts were compared. It was found that the fraction distribution of product was modified by using base catalysts such as CaO. The products from woody oils showed good cold flow properties compared with diesel used in China. The results presented in this work have shown that the catalytic cracking of woody oils generates fuels that have physical and chemical properties comparable to those specified for petroleum based fuels. PMID:20206508

  1. Catalytically propelled micro-/nanomotors: how fast can they move?

    PubMed

    Gao, Wei; Sattayasamitsathit, Sirilak; Wang, Joseph

    2012-02-01

    Synthetic micro-/nanomotors represent one of the most exciting challenges facing nanotechnology and hold considerable promise for diverse future applications. This review discusses different strategies to improve the speed of the catalytic nanomotors, summarizing and comparing the maximum absolute and relative speeds obtained with different catalytically propelled micro-/nanomotors. Remarkably ultrafast nanowires and microtube engines, with speeds of 60 and 375 body lengths s(-1), respectively, have been developed recently. Achieving such amazingly high speed and power has been accomplished through rational optimization of key factors governing the propulsion behavior, including composition of the motor and fuel, the motor morphology and various external stimuli. We hope that our discussion will serve as a guide to the rational design of even faster and more powerful catalytically propelled fuel-efficient micro-/nanomotors, with speed limits that are limited only by our imagination. PMID:22162283

  2. Catalytic ammonia decomposition over industrial-waste-supported Ru catalysts.

    PubMed

    Ng, Pei Fang; Li, Li; Wang, Shaobin; Zhu, Zhonghua; Lu, Gaoqing; Yan, Zifeng

    2007-05-15

    Industrial solid wastes (fly ash and red mud) have been employed as supports for preparation of Ru-based catalysts. Physical and chemical treatments on red mud were conducted and these modified supports were also used for preparation of Ru-based catalysts. Those Ru catalysts were characterized by various techniques such as N2 adsorption, H2 adsorption, XRD, XPS, and temperature-programmed reduction (TPR), and were then tested for catalytic ammonia decomposition to hydrogen. It was found that red-mud-supported Ru catalyst exhibits higher ammonia conversion and hydrogen production than fly-ash-supported catalyst. Heat and chemical treatments of the red mud greatly improve the catalytic activity. Moreover, a combination of acid and heat treatments produces the highest catalytic conversion of ammonia. PMID:17547209

  3. Catalytic ammonia decomposition over industrial-waste-supported Ru catalysts

    SciTech Connect

    Pei Fang Ng; Li Li; Shaobin Wang; Zhonghua Zhu; Gaoqing Lu; Zifeng Yan

    2007-05-15

    Industrial solid wastes (fly ash and red mud, a by-product of the aluminium industry) have been employed as supports for preparation of Ru-based catalysts. Physical and chemical treatments on red mud were conducted and these modified supports were also used for preparation of Ru-based catalysts. Those Ru catalysts were characterized by various techniques such as N2 adsorption, H{sub 2} adsorption, XRD, XPS, and temperature-programmed reduction (TPR), and were then tested for catalytic ammonia decomposition to hydrogen. It was found that red-mud-supported Ru catalyst exhibits higher ammonia conversion and hydrogen production than fly-ash-supported catalyst. Heat and chemical treatments of the red mud greatly improve the catalytic activity. Moreover, a combination of acid and heat treatments produces the highest catalytic conversion of ammonia. 35 refs., 4 figs., 4 tabs.

  4. A Modern Understanding of the Traditional and Nontraditional Biological Functions of Angiotensin-Converting Enzyme

    PubMed Central

    Ong, Frank S.; Blackwell, Wendell-Lamar B.; Shah, Kandarp H.; Giani, Jorge F.; Gonzalez-Villalobos, Romer A.; Shen, Xiao Z.; Fuchs, Sebastien

    2013-01-01

    Angiotensin-converting enzyme (ACE) is a zinc-dependent peptidase responsible for converting angiotensin I into the vasoconstrictor angiotensin II. However, ACE is a relatively nonspecific peptidase that is capable of cleaving a wide range of substrates. Because of this, ACE and its peptide substrates and products affect many physiologic processes, including blood pressure control, hematopoiesis, reproduction, renal development, renal function, and the immune response. The defining feature of ACE is that it is composed of two homologous and independently catalytic domains, the result of an ancient gene duplication, and ACE-like genes are widely distributed in nature. The two ACE catalytic domains contribute to the wide substrate diversity of ACE and, by extension, the physiologic impact of the enzyme. Several studies suggest that the two catalytic domains have different biologic functions. Recently, the X-ray crystal structure of ACE has elucidated some of the structural differences between the two ACE domains. This is important now that ACE domain-specific inhibitors have been synthesized and characterized. Once widely available, these reagents will undoubtedly be powerful tools for probing the physiologic actions of each ACE domain. In turn, this knowledge should allow clinicians to envision new therapies for diseases not currently treated with ACE inhibitors. PMID:23257181

  5. Sensitivity and robustness in covalent modification cycles with a bifunctional converter enzyme.

    PubMed

    Straube, Ronny

    2013-10-15

    Regulation by covalent modification is a common mechanism to transmit signals in biological systems. The modifying reactions are catalyzed either by two distinct converter enzymes or by a single bifunctional enzyme (which may employ either one or two catalytic sites for its opposing activities). The reason for this diversification is unclear, but contemporary theoretical models predict that systems with distinct converter enzymes can exhibit enhanced sensitivity to input signals whereas bifunctional enzymes with two catalytic sites are believed to generate robustness against variations in system's components. However, experiments indicate that bifunctional enzymes can also exhibit enhanced sensitivity due to the zero-order effect, raising the question whether both phenomena could be understood within a common mechanistic model. Here, I argue that this is, indeed, the case. Specifically, I show that bifunctional enzymes with two catalytic sites can exhibit both ultrasensitivity and concentration robustness, depending on the kinetic operating regime of the enzyme's opposing activities. The model predictions are discussed in the context of experimental observations of ultrasensitivity and concentration robustness in the uridylylation cycle of the PII protein, and in the phosphorylation cycle of the isocitrate dehydrogenase, respectively. PMID:24138868

  6. Exploration of the Chaotic Behaviour in a Buck-Boost Converter Depending on the Converter and Load Elements

    NASA Astrophysics Data System (ADS)

    Demirbaş, Şevki; Fidanboy, Hikmet; Kurt, Erol

    2016-03-01

    In this paper, detailed analyses of the chaotic behavior observed in a buck-boost converter are presented. Although this basic converter system is already known world-wide for the purpose of dc-dc conversion of the output of renewable energy systems, it indicates certain chaotic regimes where both the output amplitude and frequency change randomly. This chaotic regime can yield an unstable output over the resistive or resistive/inductive electrical loads. This study presents a detailed map for the regular and chaotic regions in terms of material parameters, such as converter capacitance C, resistive load R, and inductive load L. Thus, the stable area of operation for efficient and renewable electricity production will be ascertained for the studied converter system. We emphasize that the material parameters C, R, and L play important roles in generating energy from the solar cell; indeed, the stability increases with higher values of the converter capacitor and load inductance, whereas it decreases according to the resistive load. A number of periodic windows have been observed and the output frequency gives a broad-band spectrum of up to 50 kHz.

  7. Exploration of the Chaotic Behaviour in a Buck-Boost Converter Depending on the Converter and Load Elements

    NASA Astrophysics Data System (ADS)

    Demirbaş, Şevki; Fidanboy, Hikmet; Kurt, Erol

    2016-08-01

    In this paper, detailed analyses of the chaotic behavior observed in a buck-boost converter are presented. Although this basic converter system is already known world-wide for the purpose of dc-dc conversion of the output of renewable energy systems, it indicates certain chaotic regimes where both the output amplitude and frequency change randomly. This chaotic regime can yield an unstable output over the resistive or resistive/inductive electrical loads. This study presents a detailed map for the regular and chaotic regions in terms of material parameters, such as converter capacitance C, resistive load R, and inductive load L. Thus, the stable area of operation for efficient and renewable electricity production will be ascertained for the studied converter system. We emphasize that the material parameters C, R, and L play important roles in generating energy from the solar cell; indeed, the stability increases with higher values of the converter capacitor and load inductance, whereas it decreases according to the resistive load. A number of periodic windows have been observed and the output frequency gives a broad-band spectrum of up to 50 kHz.

  8. Transient Numerical Modeling of Catalytic Channels

    NASA Technical Reports Server (NTRS)

    Struk, Peter M.; Dietrich, Daniel L.; Miller, Fletcher J.; T'ien, James S.

    2007-01-01

    This paper presents a transient model of catalytic combustion suitable for isolated channels and monolith reactors. The model is a lumped two-phase (gas and solid) model where the gas phase is quasi-steady relative to the transient solid. Axial diffusion is neglected in the gas phase; lateral diffusion, however, is accounted for using transfer coefficients. The solid phase includes axial heat conduction and external heat loss due to convection and radiation. The combustion process utilizes detailed gas and surface reaction models. The gas-phase model becomes a system of stiff ordinary differential equations while the solid phase reduces, after discretization, into a system of stiff ordinary differential-algebraic equations. The time evolution of the system came from alternating integrations of the quasi-steady gas and transient solid. This work outlines the numerical model and presents some sensitivity studies on important parameters including internal transfer coefficients, catalytic surface site density, and external heat-loss (if applicable). The model is compared to two experiments using CO fuel: (1) steady-state conversion through an isothermal platinum (Pt) tube and (2) transient propagation of a catalytic reaction inside a small Pt tube. The model requires internal mass-transfer resistance to match the experiments at lower residence times. Under mass-transport limited conditions, the model reasonably predicted exit conversion using global mass-transfer coefficients. Near light-off, the model results did not match the experiment precisely even after adjustment of mass-transfer coefficients. Agreement improved for the first case after adjusting the surface kinetics such that the net rate of CO adsorption increased compared to O2. The CO / O2 surface mechanism came from a sub-set of reactions in a popular CH4 / O2 mechanism. For the second case, predictions improved for lean conditions with increased external heat loss or adjustment of the kinetics as in the

  9. Formation of ZSM-22 zeolite catalytic particles by fusion of elementary nanorods.

    PubMed

    Hayasaka, Kazuaki; Liang, Duoduo; Huybrechts, Ward; De Waele, Bart R; Houthoofd, Kristof J; Eloy, Pierre; Gaigneaux, Eric M; van Tendeloo, Gustaaf; Thybaut, Joris W; Marin, Guy B; Denayer, Joeri F M; Baron, Gino V; Jacobs, Pierre A; Kirschhock, Christine E A; Martens, Johan A

    2007-01-01

    An ZSM-22 aluminosilicate zeolite was synthesized using the hydrothermal gel method at 150 degrees C. Products obtained after different synthesis times were characterized using various techniques and catalytic testing. Massive formation of ZSM-22 nanocrystals occurs after only a short synthesis time, appearing as isolated rods with a cross section of 12+/-4 nm. Nanorods have aluminum enriched at their external surface. Later in the crystallization process nanorods align and fuse sideways, whereby the external surface is systematically converted into an internal micropore surface. The formation of aluminum bearing micropores by the joining of nanorod surfaces is responsible for the enhanced catalytic activity. For this, the zeolite synthesis of nanoscale crystallites is ineffective for enhancing catalytic activity. PMID:17868172

  10. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    SciTech Connect

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-20

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  11. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    NASA Astrophysics Data System (ADS)

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-01

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure, (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  12. Make the most of catalytic hydrogenations

    SciTech Connect

    Landert, J.P.; Scubla, T.

    1995-03-01

    Liquid-phase catalytic hydrogenation is one of the most useful and versatile reactions available for organic synthesis. Because it is environmentally clean, it has replaced other reduction processes, such as the Bechamp reaction, and zinc and sulfide reductions. Moreover, the economics are favorable, provided that raw materials free of catalyst poisons are used. The hydrogenation reaction is very selective with appropriate catalysts and can often be carried out without a solvent. Applications include reduction of unsaturated carbon compounds to saturated derivatives (for example, in vegetable-oil processing), carbonyl compounds to alcohols (such as sorbitol), and nitrocompounds to amines. the reactions are usually run in batch reactors to rapidly reach complete conversion and allow quick change-over of products. The paper describes the basics of hydrogenation; steering clear of process hazards; scale-up and optimization; and system design in practice.

  13. Catalytic desulfurization of organic sulfur compounds over zeolite catalysts

    SciTech Connect

    Sugioka, M.; Aomura, K.

    1980-03-01

    Various kinds of zeolites, such as Na-zeolites, MeY and HY, showed catalytic activity for the dehydrosulfurization of ethanethiol. The catalytic activity of MeY in the dehydrosulfurization of ethanethiol at 400/sup 0/C was changed by the kind of metal ions in the zeolites and a volcano shape order was observed between the catalytic activity and the electronegativity, Xi, of the metal ions. The order of the catalytic activity was NaX>NaY>NaA. The changes in the activity of HY in ethanethiol dehydrosulfurization and cumene dealkylation by calcination agreed with the decrease in the Bronsted acidity determined by Ward but was independent of Lewis acidity. Me/sup 0/Y, such as Co/sup 0/Y, Ni/sup 0/Y, Cu/sup 0/Y and Ag/sup 0/Y, showed higher catalytic activity than a commercial hydrodesulfurization catalyst and the order of the activity was Ni/sup 0/Y>Co/sup 0/Y>Cu/sup 0/Y>Ag/sup 0/Y. Reduced and presulfided Me/sup 0/Y zeolites showed selective hydrodesulfurization activity for thiophene. The remarkable promoting effect of NiO and MoO/sub 3/ upon the catalytic activity of Me/sup 0/Y was not observed in the hydrodesulfurization of thiophene. Zeolite catalysts have a possibility of use as effective hydrodesulfurization catalysts for petroleum if further improvement in catalyst deactivation of Me/sup 0/Y zeolite is accomplished. The investigation of the hydrodesulfurization of thiophene over Me/sup 0/Y zeolites would become a good model to clarify the mechanism of the hydrodesulfurization of petroleum.

  14. Catalytic combustion of residual fuels

    NASA Technical Reports Server (NTRS)

    Bulzan, D. L.; Tacina, R. R.

    1981-01-01

    A noble metal catalytic reactor was tested using two grades of petroleum derived residual fuels at specified inlet air temperatures, pressures, and reference velocities. Combustion efficiencies greater than 99.5 percent were obtained. Steady state operation of the catalytic reactor required inlet air temperatures of at least 800 K. At lower inlet air temperatures, upstream burning in the premixing zone occurred which was probably caused by fuel deposition and accumulation on the premixing zone walls. Increasing the inlet air temperature prevented this occurrence. Both residual fuels contained about 0.5 percent nitrogen by weight. NO sub x emissions ranged from 50 to 110 ppm by volume at 15 percent excess O2. Conversion of fuel-bound nitrogen to NO sub x ranged from 25 to 50 percent.

  15. Vapor Phase Catalytic Ammonia Reduction

    NASA Technical Reports Server (NTRS)

    Flynn, Michael T.; Harper, Lynn D. (Technical Monitor)

    1994-01-01

    This paper discusses the development of a Vapor Phase Catalytic Ammonia Reduction (VPCAR) teststand and the results of an experimental program designed to evaluate the potential of the technology as a water purification process. In the experimental program the technology is evaluated based upon product water purity, water recovery rate, and power consumption. The experimental work demonstrates that the technology produces high purity product water and attains high water recovery rates at a relatively high specific power consumption. The experimental program was conducted in 3 phases. In phase I an Igepon(TM) soap and water mixture was used to evaluate the performance of an innovative Wiped-Film Rotating-Disk evaporator and associated demister. In phase II a phenol-water solution was used to evaluate the performance of the high temperature catalytic oxidation reactor. In phase III a urine analog was used to evaluate the performance of the combined distillation/oxidation functions of the processor.

  16. Cutoff lensing: predicting catalytic sites in enzymes

    PubMed Central

    Aubailly, Simon; Piazza, Francesco

    2015-01-01

    Predicting function-related amino acids in proteins with unknown function or unknown allosteric binding sites in drug-targeted proteins is a task of paramount importance in molecular biomedicine. In this paper we introduce a simple, light and computationally inexpensive structure-based method to identify catalytic sites in enzymes. Our method, termed cutoff lensing, is a general procedure consisting in letting the cutoff used to build an elastic network model increase to large values. A validation of our method against a large database of annotated enzymes shows that optimal values of the cutoff exist such that three different structure-based indicators allow one to recover a maximum of the known catalytic sites. Interestingly, we find that the larger the structures the greater the predictive power afforded by our method. Possible ways to combine the three indicators into a single figure of merit and into a specific sequential analysis are suggested and discussed with reference to the classic case of HIV-protease. Our method could be used as a complement to other sequence- and/or structure-based methods to narrow the results of large-scale screenings. PMID:26445900

  17. Catalytic reactor for low-Btu fuels

    DOEpatents

    Smith, Lance; Etemad, Shahrokh; Karim, Hasan; Pfefferle, William C.

    2009-04-21

    An improved catalytic reactor includes a housing having a plate positioned therein defining a first zone and a second zone, and a plurality of conduits fabricated from a heat conducting material and adapted for conducting a fluid therethrough. The conduits are positioned within the housing such that the conduit exterior surfaces and the housing interior surface within the second zone define a first flow path while the conduit interior surfaces define a second flow path through the second zone and not in fluid communication with the first flow path. The conduit exits define a second flow path exit, the conduit exits and the first flow path exit being proximately located and interspersed. The conduits define at least one expanded section that contacts adjacent conduits thereby spacing the conduits within the second zone and forming first flow path exit flow orifices having an aggregate exit area greater than a defined percent of the housing exit plane area. Lastly, at least a portion of the first flow path defines a catalytically active surface.

  18. Cutoff lensing: predicting catalytic sites in enzymes

    NASA Astrophysics Data System (ADS)

    Aubailly, Simon; Piazza, Francesco

    2015-10-01

    Predicting function-related amino acids in proteins with unknown function or unknown allosteric binding sites in drug-targeted proteins is a task of paramount importance in molecular biomedicine. In this paper we introduce a simple, light and computationally inexpensive structure-based method to identify catalytic sites in enzymes. Our method, termed cutoff lensing, is a general procedure consisting in letting the cutoff used to build an elastic network model increase to large values. A validation of our method against a large database of annotated enzymes shows that optimal values of the cutoff exist such that three different structure-based indicators allow one to recover a maximum of the known catalytic sites. Interestingly, we find that the larger the structures the greater the predictive power afforded by our method. Possible ways to combine the three indicators into a single figure of merit and into a specific sequential analysis are suggested and discussed with reference to the classic case of HIV-protease. Our method could be used as a complement to other sequence- and/or structure-based methods to narrow the results of large-scale screenings.

  19. Catalytic asymmetric alkylation of acylsilanes.

    PubMed

    Rong, Jiawei; Oost, Rik; Desmarchelier, Alaric; Minnaard, Adriaan J; Harutyunyan, Syuzanna R

    2015-03-01

    The highly enantioselective addition of Grignard reagents to acylsilanes is catalyzed by copper diphosphine complexes. This transformation affords α-silylated tertiary alcohols in up to 97% yield and 98:2 enantiomeric ratio. The competing Meerwein-Ponndorf-Verley reduction is suppressed by the use of a mixture of Lewis acid additives. The chiral catalyst can be recovered as a copper complex and used repeatedly without any loss of catalytic activity. PMID:25403641

  20. RF digital-to-analog converter

    DOEpatents

    Conway, P.H.; Yu, D.U.L.

    1995-02-28

    A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

  1. High-Efficiency dc/dc Converter

    NASA Technical Reports Server (NTRS)

    Sturman, J.

    1982-01-01

    High-efficiency dc/dc converter has been developed that provides commonly used voltages of plus or minus 12 Volts from an unregulated dc source of from 14 to 40 Volts. Unique features of converter are its high efficiency at low power level and ability to provide output either larger or smaller than input voltage.

  2. Passive Resonant Bidirectional Converter with Galvanic Barrier

    NASA Technical Reports Server (NTRS)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  3. Controller for a wave energy converter

    SciTech Connect

    Wilson, David G.; Bull, Diana L.; Robinett, III, Rush D.

    2015-09-22

    A wave energy converter (WEC) is described, the WEC including a power take off (PTO) that converts relative motion of bodies of the WEC into electrical energy. A controller controls operation of the PTO, causing the PTO to act as a motor to widen a wave frequency spectrum that is usable to generate electrical energy.

  4. RF digital-to-analog converter

    DOEpatents

    Conway, Patrick H.; Yu, David U. L.

    1995-01-01

    A digital-to analogue converter for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration.

  5. Power Converters Secure Electronics in Harsh Environments

    NASA Technical Reports Server (NTRS)

    2013-01-01

    In order to harden power converters for the rigors of space, NASA awarded multiple SBIR contracts to Blacksburg, Virginia-based VPT Inc. The resulting hybrid DC-DC converters have proven valuable in aerospace applications, and as a result the company has generated millions in revenue from the product line and created four high-tech jobs to handle production.

  6. Distributed electrical leads for thermionic converter

    DOEpatents

    Fitzpatrick, Gary O.; Britt, Edward J.

    1979-01-01

    In a thermionic converter, means are provided for coupling an electrical lead to at least one of the electrodes thereof. The means include a bus bar and a plurality of distributed leads coupled to the bus bar each of which penetrates through one electrode and are then coupled to the other electrode of the converter in spaced apart relation.

  7. Thermodynamics of catalytic nanoparticle morphology

    NASA Astrophysics Data System (ADS)

    Zwolak, Michael; Sharma, Renu; Lin, Pin Ann

    Metallic nanoparticles are an important class of industrial catalysts. The variability of their properties and the environment in which they act, from their chemical nature & surface modification to their dispersion and support, allows their performance to be optimized for many chemical processes useful in, e.g., energy applications and other areas. Their large surface area to volume ratio, as well as varying sizes and faceting, in particular, makes them an efficient source for catalytically active sites. These characteristics of nanoparticles - i.e., their morphology - can often display intriguing behavior as a catalytic process progresses. We develop a thermodynamic model of nanoparticle morphology, one that captures the competition of surface energy with other interactions, to predict structural changes during catalytic processes. Comparing the model to environmental transmission electron microscope images of nickel nanoparticles during carbon nanotube (and other product) growth demonstrates that nickel deformation in response to the nanotube growth is due to a favorable interaction with carbon. Moreover, this deformation is halted due to insufficient volume of the particles. We will discuss the factors that influence morphology and also how the model can be used to extract interaction strengths from experimental observations.

  8. Three powerful dinuclear metal-organic catalysts for converting CO2 into organic carbonates.

    PubMed

    Zhao, Dan; Liu, Xiao-Hui; Shi, Zhuang-Zhi; Zhu, Chen-Dan; Zhao, Yue; Wang, Peng; Sun, Wei-Yin

    2016-09-28

    Developing efficient catalysts for converting carbon dioxide (CO2) into varied organic carbonates is an important scientific goal. By using the NH2-functionalized tripodal ligand 2-((bis(2-aminoethyl)amino)methyl)phenol (HL), three dinuclear metal-organic complexes [Zn(L)]2·2ClO4 (1), [Cu(L)]2·2ClO4·2H2O (2) and [Cd(L)]2·2ClO4 (3) have been successfully isolated and structurally characterized using single-crystal X-ray diffraction analyses. Considering the dinuclear metal centers and the NH2-functional groups in the structures, 1-3 were investigated as catalysts for converting CO2 into organic carbonates, and the results show that 1-3 exhibit an outstanding ability for converting CO2 into varied organic carbonates at atmospheric pressure (0.1 MPa). The catalytic system also displays a wide substrate scope and high catalytic activity, and the reaction mechanism has been proposed herein. PMID:27530724

  9. Radiation Effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25

  10. Comparison of Different Methods for Calculating Gyrotron Quasi-Optical Mode Converters

    NASA Astrophysics Data System (ADS)

    Gashturi, A. P.; Chirkov, A. V.; Denisov, G. G.; Paveliev, A. B.

    2013-01-01

    This paper presents the use of combination of three methods for calculation and synthesis of high-efficiency microwave mode converters, such as radiators of gyrotrons. The analytical method yields immediate estimates of mode converter dimensions, the Scalar Integral Equation (SIE) allows one to synthesize efficiently the optimal profile of the mode converter, and the most accurate Electric Field Integral Equation (EFIE) is used to check all transmission characteristics of the converter including calculations of reflection and cross-polarization. The combination of these three methods is an optimal for the mode converter design. Just so the launcher was designed for a quasi-optical mode converter used in the 60 GHz gyrotron in the TE7,3 operating mode. The simulation results agree well with the measured data. The paper also presents for the first time an accurate derivation of the SIE method.

  11. Optimum Design of CMOS DC-DC Converter for Mobile Applications

    NASA Astrophysics Data System (ADS)

    Katayama, Yasushi; Edo, Masaharu; Denta, Toshio; Kawashima, Tetsuya; Ninomiya, Tamotsu

    In recent years, low output power CMOS DC-DC converters which integrate power stage MOSFETs and a PWM controller using CMOS process have been used in many mobile applications. In this paper, we propose the calculation method of CMOS DC-DC converter efficiency and report optimum design of CMOS DC-DC converter based on this method. By this method, converter efficiencies are directly calculated from converter specifications, dimensions of power stage MOSFET and device parameters. Therefore, this method can be used for optimization of CMOS DC-DC converter design, such as dimensions of power stage MOSFET and switching frequency. The efficiency calculated by the proposed method agrees well with the experimental results.

  12. Modelling, analyses and design of switching converters

    NASA Technical Reports Server (NTRS)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  13. High frequency converters for thermophotovoltaic applications

    SciTech Connect

    Fatemi, N.S.; Hoffman, R.W. Jr.; Lowe, R.A.; Jenkins, P.P.; Garverick, L.M.; Wilt, D.M.; Scheiman, D.

    1996-12-31

    Thermophotovoltaic (TPV) converters were developed and tested at the heat source operating temperature of 1,700 K. Rare-earth-doped yttrium aluminum garnet (YAG) and lutetium yttrium aluminum garnet (Lu, YAG) selective emitters, as well as a blackbody emitter, were coupled to InGaAs/InP photovoltaic (PV) cells and bandpass/infrared (IR) reflector filters. YAG-based selective emitters were adopted with Ho, Tm, and Er. PV cells had bandgaps of 0.51, 0.57, and 0.69 eV. Converter energy conversion efficiencies approaching 30%, as well as electrical output power densities near 2 W/cm{sup 2} were demonstrated. The overall performance of the filtered blackbody-based converter was found to be superior to the selective emitter YAG-based converters. The details of the measurements performed on the above converters and their individual components are presented.

  14. Evaluations of uranium-nitride fueled converters.

    NASA Technical Reports Server (NTRS)

    Shimada, K.; Cassell, P. L.

    1971-01-01

    Evaluation of two uranium-nitride (UN) fueled converters was initiated at the Jet Propulsion Laboratory to investigate the effect of fuel on the converter performance while being operated out-of-core. The initial tests were performed with the dynamic data acquisition system that was developed at the Laboratory. Parametric tests of these converters were to obtain: (1) static volt-ampere curves, (2) dynamic volt-ampere curves, and (3) the electrode work functions. The power outputs were 9.3 W/sq cm for the rhenium converter and 3.8 W/sq cm for the tungsten converter at 0.6 V when the emitter surface temperature was 2000 K, according to the static volt-ampere curves.

  15. Qualitative model of a plasma photoelectric converter

    NASA Astrophysics Data System (ADS)

    Gorbunov, N. A.; Flamant, G.

    2009-01-01

    A converter of focused optical radiation into electric current is considered on the basis of the photovoltaic effect in plasmas. The converter model is based on analysis of asymmetric spatial distributions of charge particle number density and ambipolar potential in the photoplasma produced by external optical radiation focused in a heat pipe filled with a mixture of alkali vapor and a heavy inert gas. Energy balance in the plasma photoelectric converter is analyzed. The conditions in which the external radiation energy is effectively absorbed in the converter are indicated. The plasma parameters for which the energy of absorbed optical radiation is mainly spent on sustaining the ambipolar field in the plasma are determined. It is shown that the plasma photoelectric converter makes it possible to attain a high conversion efficiency for focused solar radiation.

  16. Boost matrix converters in clean energy systems

    NASA Astrophysics Data System (ADS)

    Karaman, Ekrem

    This dissertation describes an investigation of novel power electronic converters, based on the ultra-sparse matrix topology and characterized by the minimum number of semiconductor switches. The Z-source, Quasi Z-source, Series Z-source and Switched-inductor Z-source networks were originally proposed for boosting the output voltage of power electronic inverters. These ideas were extended here on three-phase to three-phase and three-phase to single-phase indirect matrix converters. For the three-phase to three-phase matrix converters, the Z-source networks are placed between the three-switch input rectifier stage and the output six-switch inverter stage. A brief shoot-through state produces the voltage boost. An optimal pulse width modulation technique was developed to achieve high boosting capability and minimum switching losses in the converter. For the three-phase to single-phase matrix converters, those networks are placed similarly. For control purposes, a new modulation technique has been developed. As an example application, the proposed converters constitute a viable alternative to the existing solutions in residential wind-energy systems, where a low-voltage variable-speed generator feeds power to the higher-voltage fixed-frequency grid. Comprehensive analytical derivations and simulation results were carried out to investigate the operation of the proposed converters. Performance of the proposed converters was then compared between each other as well as with conventional converters. The operation of the converters was experimentally validated using a laboratory prototype.

  17. Power Management and Distribution System Developed for Thermionic Power Converters

    NASA Technical Reports Server (NTRS)

    Baez, Anastacio N.

    1998-01-01

    A spacecraft solar, bimodal system combines propulsion and power generation into a single integrated system. An Integrated Solar Upper Stage (ISUS) provides orbital transfer capabilities, power generation for payloads, and onboard propulsion to the spacecraft. A key benefit of a bimodal system is a greater payload-to-spacecraft mass ratio resulting in lower launch vehicle requirements. Scaling down to smaller launch vehicles increases space access by reducing overall mission cost. NASA has joined efforts with the Air Force Phillips Laboratory to develop enabling technologies for such a system. The NASA/Air Force bimodal concept uses solar concentrators to focus energy into an integrated power plant. This power plant consists of a graphite core that stores thermal energy within a cavity. An array of thermionic converters encircles the graphite cavity and provides electrical energy conversion functions. During the power generation phase of the bimodal system, the thermionic converters are exposed to the heated cavity and convert the thermal energy to electricity. Near-term efforts of the ISUS bimodal program are focused on a ground demonstration of key technologies in order to proceed to a full space flight test. Thermionic power generation is one key technology of the bimodal concept. Thermionic power converters impose unique operating requirements upon a power management and distribution (PMAD) system design. Single thermionic converters supply large currents at very low voltages. Operating voltages can vary over a range of up to 3 to 1 as a function of operating temperature. Most spacecraft loads require regulated 28-volts direct-current (Vdc) power. A combination of series-connected converters and powerprocessing boosters is required to deliver power to the spacecraft's payloads at this level.

  18. A Methodology to Teach Advanced A/D Converters, Combining Digital Signal Processing and Microelectronics Perspectives

    ERIC Educational Resources Information Center

    Quintans, C.; Colmenar, A.; Castro, M.; Moure, M. J.; Mandado, E.

    2010-01-01

    ADCs (analog-to-digital converters), especially Pipeline and Sigma-Delta converters, are designed using complex architectures in order to increase their sampling rate and/or resolution. Consequently, the learning of ADC devices also encompasses complex concepts such as multistage synchronization, latency, oversampling, modulation, noise shaping,…

  19. Experimental studies and computer simulation of the control of energy transfer using inductor-converter bridges

    SciTech Connect

    Hirano, M.; Kustom, R.L.

    1984-03-01

    An inductor-converter bridge (ICB) is a solid state DC-AC-DC power converter system for bidirectional, controllable, energy transfer between two coils. The ICB is suitable for supplying large pulsed power to such magnets as the superconducting equilibrium field coil of the proposed tokamak power reactors from another superconducting energy storage coil.

  20. Catalytic Preparation of Pyrrolidones from Renewable Resources

    SciTech Connect

    Frye, John G.; Zacher, Alan H.; Werpy, Todd A.; Wang, Yong

    2005-06-01

    Abstract Use of renewable resources for production of valuable chemical commodities is becoming a topic of great national interest and importance. This objective fits well with the U.S. DOE’s objective of promoting the industrial bio-refinery concept in which a wide array of valuable chemical, fuel, food, nutraceuticals, and animal feed products all result from the integrated processing of grains, oil seeds, and other bio-mass materials. The bio-refinery thus serves to enhance the overall utility and profitability of the agriculture industry as well as helping to reduce the USA’s dependence on petroleum. Pyrrolidones fit well into the bio-refinery concept since they may be produced in a scheme beginning with the fermentation of a portion of the bio-refinery’s sugar product into succinate. Pyrrolidones are a class of industrially important chemicals with a variety of uses including polymer intermediates, cleaners, and “green solvents” which can replace hazardous chlorinated compounds. Battelle has developed an efficient process for the thermo-catalytic conversion of succinate into pyrrolidones, especially n-methyl-2-pyrrolidone. The process uses both novel Rh based catalysts and novel aqueous process conditions and results in high selectivities and yields of pyrrolidone compounds. The process also includes novel methodology for enhancing yields by recycling and converting non-useful side products of the catalysis into additional pyrrolidone. The process has been demonstrated in both batch and continuous reactors. Additionally, stability of the unique Rh-based catalyst has been demonstrated.

  1. Structured materials for catalytic and sensing applications

    NASA Astrophysics Data System (ADS)

    Hokenek, Selma

    The optical and chemical properties of the materials used in catalytic and sensing applications directly determine the characteristics of the resultant catalyst or sensor. It is well known that a catalyst needs to have high activity, selectivity, and stability to be viable in an industrial setting. The hydrogenation activity of palladium catalysts is known to be excellent, but the industrial applications are limited by the cost of obtaining catalyst in amounts large enough to make their use economical. As a result, alloying palladium with a cheaper, more widely available metal while maintaining the high catalytic activity seen in monometallic catalysts is, therefore, an attractive option. Similarly, the optical properties of nanoscale materials used for sensing must be attuned to their application. By adjusting the shape and composition of nanoparticles used in such applications, very fine changes can be made to the frequency of light that they absorb most efficiently. The design, synthesis, and characterization of (i) size controlled monometallic palladium nanoparticles for catalytic applications, (ii) nickel-palladium bimetallic nanoparticles and (iii) silver-palladium nanoparticles with applications in drug detection and biosensing through surface plasmon resonance, respectively, will be discussed. The composition, size, and shape of the nanoparticles formed were controlled through the use of wet chemistry techniques. After synthesis, the nanoparticles were analyzed using physical and chemical characterization techniques such as X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Scanning Transmission Electron Microscopy- Energy-Dispersive Spectrometry (STEM-EDX). The Pd and Ni-Pd nanoparticles were then supported on silica for catalytic testing using mass spectrometry. The optical properties of the Ag-Pd nanoparticles in suspension were further investigated using ultraviolet-visible spectrometry (UV-Vis). Monometallic palladium particles have

  2. Fast and quantitative measurement of benzene, toluene and C 2-benzenes in automotive exhaust during transient engine operation with and without catalytic exhaust gas treatment

    NASA Astrophysics Data System (ADS)

    Heeb, Norbert V.; Forss, Anna-Maria; Bach, Christian

    Time-Resolved Chemical Ionization Mass Spectrometry (CIMS) has been used to investigate the emission profiles of benzene, toluene and the C 2-benzenes (xylenes and ethyl benzene) in automotive exhaust during transient engine operation. On-line emission measurements with a frequency of 1-5 Hz clearly identified the critical driving conditions that are mainly responsible for the overall aromatic hydrocarbon emissions. The passenger car, equipped with a catalytic converter showed significant BTXE-emissions only in the first part of the New European Driving Cycle (NEDC) due to sub-optimal catalyst temperature. On the same car without a catalytic converter, emissions of aromatic hydrocarbons were detected over the entire test run and the benzene-toluene mixing ratios of the exhaust gas were rather constant. With catalytic exhaust gas treatment the observed benzene-toluene mixing ratios varied to a greater extent reflecting predominantly different catalytic converter conditions. The average molar ratio of benzene over toluene rose from 0.33 to 0.53 upon exhaust gas treatment. With catalytic converter the emissions during extra urban (EUDC) driving repeatedly showed benzene-toluene mixing ratios >1 and an average molar benzene/toluene ratio of 0.74 was detected during the EUDC part of the driving cycle. Whereas the total hydrocarbon (T.HC) emissions were decreased by 83% upon exhaust gas treatment the overall reduction of the benzene emissions was only 70%.

  3. Catalytic Hydroprocessing of Biomass Fast Pyrolysis Bio-oil to Produce Hydrocarbon Products

    SciTech Connect

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Rotness, Leslie J.; Zacher, Alan H.

    2009-10-01

    Catalytic hydroprocessing has been applied to biomass fast pyrolysis liquid product (bio-oil) in a bench-scale continuous-flow fixed-bed reactor system. The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock. The project was a cooperative research and development agreement among UOP LLC, the National Renewable Energy Laboratory and the Pacific Northwest National Laboratory (PNNL). This paper is focused on the process experimentation and product analysis undertaken at PNNL. The paper describes the experimental methods used and relates the results of the product analyses. A range of catalyst formulations were tested over a range of operating parameters including temperature, pressure, and flow-rate with bio-oil derived from several different biomass feedstocks. Effects of liquid hourly space velocity and catalyst bed temperature were assessed. Details of the process results were presented including mass and elemental balances. Detailed analysis of the products were provided including elemental composition, chemical functional type determined by mass spectrometry, and product descriptors such as density, viscosity and Total Acid Number (TAN). In summation, the paper provides an understanding of the efficacy of hydroprocessing as applied to bio-oil.

  4. Catalytic Hydroprocessing of Fast Pyrolysis Bio-oil from Pine Sawdust

    SciTech Connect

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Rotness, Leslie J.; Olarte, Mariefel V.; Zacher, Alan H.; Solantausta, Yrjo

    2012-06-01

    Catalytic hydroprocessing has been applied to the fast pyrolysis liquid product (bio-oil) from softwood biomass in a bench-scale continuous-flow fixed-bed reactor system. The intent of the research was to develop process technology to convert the bio-oil into a petroleum refinery feedstock to supplement fossil energy resources and to displace imported feedstock. This paper is focused on the process experimentation and product analysis. The paper describes the experimental methods used and relates the results of the product analyses. A range of operating parameters including temperature, and flow-rate were tested with bio-oil derived from pine wood as recovered and pyrolyzed in the pilot pyrolyzer of Metso Power in Tampere, Finland. Effects of time on stream and catalyst activity were assessed. Details of the process results were presented included product yields and hydrogen consumption. Detailed analysis of the products were provided including elemental composition and product descriptors such as density, viscosity and Total Acid Number (TAN). In summation, the paper provides an initial understanding of the efficacy of hydroprocessing as applied to the Finnish pine bio-oil.

  5. Catalytic conversion of carbohydrates into 5-hydroxymethylfurfural over cellulose-derived carbonaceous catalyst in ionic liquid.

    PubMed

    Hu, Lei; Zhao, Geng; Tang, Xing; Wu, Zhen; Xu, Jiaxing; Lin, Lu; Liu, Shijie

    2013-11-01

    Three environmental-benign and low-cost carbon-based solid acid catalysts containing -SO3H, -COOH and phenolic -OH groups were prepared and used for the conversion of glucose into 5-hydroxymethylfurfural (HMF) in ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl). The results demonstrated that cellulose-derived carbonaceous catalyst (CCC) possessed the highest catalytic activity, which resulted in 46.4% HMF yield at 160°C for only 15 min. In addition, the reaction kinetics for the conversion of glucose into HMF over CCC was fitted with the first-order rate equation. The slightly-deactivated CCC after four successive reaction runs could be easily regenerated by a simple carbonization and sulfonation process. More gratifyingly, the combination of CCC and [BMIM]Cl were confirmed to be suitable for converting other carbohydrates such as fructose, sucrose, maltose, cellobiose, starch and cellulose into HMF. Particularly, a plausible mechanism involving hydrolysis, isomerization and dehydration for the conversion of carbohydrates into HMF was also proposed. PMID:24090810

  6. TET2 Regulates Mast Cell Differentiation and Proliferation through Catalytic and Non-catalytic Activities.

    PubMed

    Montagner, Sara; Leoni, Cristina; Emming, Stefan; Della Chiara, Giulia; Balestrieri, Chiara; Barozzi, Iros; Piccolo, Viviana; Togher, Susan; Ko, Myunggon; Rao, Anjana; Natoli, Gioacchino; Monticelli, Silvia

    2016-05-17

    Dioxygenases of the TET family impact genome functions by converting 5-methylcytosine (5mC) in DNA to 5-hydroxymethylcytosine (5hmC). Here, we identified TET2 as a crucial regulator of mast cell differentiation and proliferation. In the absence of TET2, mast cells showed disrupted gene expression and altered genome-wide 5hmC deposition, especially at enhancers and in the proximity of downregulated genes. Impaired differentiation of Tet2-ablated cells could be relieved or further exacerbated by modulating the activity of other TET family members, and mechanistically it could be linked to the dysregulated expression of C/EBP family transcription factors. Conversely, the marked increase in proliferation induced by the loss of TET2 could be rescued exclusively by re-expression of wild-type or catalytically inactive TET2. Our data indicate that, in the absence of TET2, mast cell differentiation is under the control of compensatory mechanisms mediated by other TET family members, while proliferation is strictly dependent on TET2 expression. PMID:27160912

  7. Heterogeneous kinetic modeling of the catalytic conversion of cycloparaffins

    NASA Astrophysics Data System (ADS)

    Al-Sabawi, Mustafa N.

    The limited availability of high value light hydrocarbon feedstocks along with the rise in crude prices has resulted in the international recognition of the vast potential of Canada's oil sands. With the recent expansion of Canadian bitumen production come, however, many technical challenges, one of which is the significant presence of aromatics and cycloparaffins in bitumen-derived feedstocks. In addition to their negative environmental impact, aromatics limit fluid catalytic cracking (FCC) feedstock conversion, decrease the yield and quality of valuable products such as gasoline and middle distillates, increase levels of polyaromatic hydrocarbons prone to form coke on the catalyst, and ultimately compromise the FCC unit performance. Although cycloparaffins do not have such negative impacts, they are precursors of aromatics as they frequently undergo hydrogen transfer reactions. However, cycloparaffin cracking chemistry involves other competing reactions that are complex and need much investigation. This dissertation provides insights and understanding of the fundamentals of the catalytic cracking of cycloparaffins using carefully selected model compounds such as methylcyclohexane (MCH) and decalin. Thermal and catalytic cracking of these cycloparaffins on FCC-type catalysts are carried out using the CREC Riser Simulator under operating conditions similar to those of the industrial FCC units in terms of temperature, reaction time, reactant partial pressure and catalyst-to-hydrocarbon ratio. The crystallite size of the supported zeolites is varied between 0.4 and 0.9 microns, with both activity and selectivity being monitored. Catalytic conversions ranged between 4 to 16 wt% for MCH and between 8 to 27 wt% for decalin. Reaction pathways of cycloparaffins are determined, and these include ring-opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. The yields and selectivities of over 60 and 140 products, formed during MCH and decalin

  8. Manual control of catalytic reactions: Reactions by an apoenzyme gel and a cofactor gel

    PubMed Central

    Kobayashi, Yuichiro; Takashima, Yoshinori; Hashidzume, Akihito; Yamaguchi, Hiroyasu; Harada, Akira

    2015-01-01

    Enzymes play a vital role in catalysing almost all chemical reactions that occur in biological systems. Some enzymes must form complexes with non-protein molecules called cofactors to express catalytic activities. Although the control of catalytic reactions via apoenzyme–cofactor complexes has attracted significant attention, the reports have been limited to the microscale. Here, we report a system to express catalytic activity by adhesion of an apoenzyme gel and a cofactor gel. The apoenzyme and cofactor gels act as catalysts when they form a gel assembly, but they lose catalytic ability upon manual dissociation. We successfully construct a system with switchable catalytic activity via adhesion and separation of the apoenzyme gel with the cofactor gel. We expect that this methodology can be applied to regulate the functional activities of enzymes that bear cofactors in their active sites, such as the oxygen transport of haemoglobin or myoglobin and the electron transport of cytochromes. PMID:26537172

  9. Manual control of catalytic reactions: Reactions by an apoenzyme gel and a cofactor gel

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yuichiro; Takashima, Yoshinori; Hashidzume, Akihito; Yamaguchi, Hiroyasu; Harada, Akira

    2015-11-01

    Enzymes play a vital role in catalysing almost all chemical reactions that occur in biological systems. Some enzymes must form complexes with non-protein molecules called cofactors to express catalytic activities. Although the control of catalytic reactions via apoenzyme-cofactor complexes has attracted significant attention, the reports have been limited to the microscale. Here, we report a system to express catalytic activity by adhesion of an apoenzyme gel and a cofactor gel. The apoenzyme and cofactor gels act as catalysts when they form a gel assembly, but they lose catalytic ability upon manual dissociation. We successfully construct a system with switchable catalytic activity via adhesion and separation of the apoenzyme gel with the cofactor gel. We expect that this methodology can be applied to regulate the functional activities of enzymes that bear cofactors in their active sites, such as the oxygen transport of haemoglobin or myoglobin and the electron transport of cytochromes.

  10. Soluble organic nanotubes for catalytic systems.

    PubMed

    Xiong, Linfeng; Yang, Kunran; Zhang, Hui; Liao, Xiaojuan; Huang, Kun

    2016-03-18

    In this paper, we report a novel method for constructing a soluble organic nanotube supported catalyst system based on single-molecule templating of core–shell bottlebrush copolymers. Various organic or metal catalysts, such as sodium prop-2-yne-1-sulfonate (SPS), 1-(2-(prop-2-yn-1-yloxy)ethyl)-1H-imidazole (PEI) and Pd(OAc)2 were anchored onto the tube walls to functionalize the organic nanotubes via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Depending on the 'confined effect' and the accessible cavity microenvironments of tubular structures, the organic nanotube catalysts showed high catalytic efficiency and site-isolation features. We believe that the soluble organic nanotubes will be very useful for the development of high performance catalyst systems due to their high stability of support, facile functionalization and attractive textural properties. PMID:27308672

  11. Scanning electrochemical microscopy of individual catalytic nanoparticles.

    PubMed

    Sun, Tong; Yu, Yun; Zacher, Brian J; Mirkin, Michael V

    2014-12-15

    Electrochemistry at individual metal nanoparticles (NPs) can provide new insights into their electrocatalytic behavior. Herein, the electrochemical activity of single AuNPs attached to the catalytically inert carbon surface is mapped by using extremely small (≥3 nm radius) polished nanoelectrodes as tips in the scanning electrochemical microscope (SECM). The use of such small probes resulted in the spatial resolution significantly higher than in previously reported electrochemical images. The currents produced by either rapid electron transfer or the electrocatalytic hydrogen evolution reaction at a single 10 or 20 nm NP were measured and quantitatively analyzed. The developed methodology should be useful for studying the effects of nanoparticle size, geometry, and surface attachment on electrocatalytic activity in real-world application environment. PMID:25332196

  12. Basicity, Catalytic and Adsorptive Properties of Hydrotalcites

    NASA Astrophysics Data System (ADS)

    Figueras, Francois

    Solid bases have numerous potential applications, not only as catalyst for the manufacture of fine chemicals, in refining and petrochemistry, but also for adsorption and anion exchange. The present processes use liquid bases, typically alcoholic potash, and require neutralisation of the reaction medium at the end of the reaction, with production of salts. The substitution of these liquid bases by solids would provide cleaner and safer processes, due to the reduction of salts, and facilitate separation of the products and recycling of the catalyst. This chapter reviews the recent ideas on the modification of the basic properties of hydrotalcites by anion exchange and on the catalytic properties of solid bases as catalysts. Many examples of successful applications are given, with emphasis to industrial processes recently presented such as isomerisation of olefins. The basic properties of hydrotalcites can also be used to carry the exchange of toxic anions, humic acids or dyes, and have driven recent developments proposing HDT as drug carriers.

  13. Programmable Analog-To-Digital Converter

    NASA Technical Reports Server (NTRS)

    Kist, Edward H., Jr.

    1993-01-01

    High-speed analog-to-digital converter with programmable voltage steps that can be changed during operation. Allows concentration of converter resolution over specific portion of waveform. Particularly useful in digitizing wind-shear radar and lidar return signals, in digital oscilloscopes, and other applications in which desirable to increase digital resolution over specific area of waveform while accepting lower resolution over rest of waveform. Effective increase in dynamic range achieved without increase in number of analog-to-digital converter bits. Enabling faster analog-to-digital conversion.

  14. Electro Catalytic Oxidation (ECO) Operation

    SciTech Connect

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large scale capture and

  15. Electrical power converter method and system employing multiple output converters

    DOEpatents

    Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

    2007-05-01

    A support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

  16. Multi-bandgap high efficiency converter (RAINBOW)

    SciTech Connect

    Lewis, C.R.; Phillips, W.M.; Shields, V.B.; Stella, P.M.; Bekey, I.

    1997-12-31

    Many proposals have been made to increase solar array efficiency by using two or more cells with appropriately spaced bandgaps to span a greater portion of the incident spectrum. One such technique is to split the solar spectrum and focus each portion on a different cell bandgap. Each bandgap is selected to best match the input spectral portion and thus obtain maximum efficiency. This paper reports on the reexamination of the spectrally split, individually matched cell approach using modern-day optics and lightweight structures. The RAINBOW multi-bandgap system represents a unique combination of solar cells, concentrators and beam splitters. The use of separate cells offers the widest possible scope of material choices. Many different component combinations are possible. The relatively low temperature operation, due to reduced thermal input per cell, adds to the performance increase. Finally, RAINBOW is a flexible system which can readily expand as new high efficiency components are developed. Based to a large extent on data for real cells and optical components, RAINBOW is expected to convert over 40% of incident solar energy to electricity at the system level. This conclusion is based on preliminary analyses of cell and optics performances.

  17. Converting mixed waste into durable glass

    SciTech Connect

    Ruller, J.A.; Greenman, W.G.

    1994-12-31

    Radioactive, hazardous and mixed contamination of soils and sediments within the Weapons Complex is widespread and estimated to total billions of cubic meters. The cost to remediate this contamination, as well as the contaminated surface and groundwaters, buildings and facilities has been estimated to be up to $300 billion over the next 30 years and up to $30 billion over the next five years. Progress towards cleaning the Weapons Complex depends upon the development of new remediation technologies. The remediation of contaminated soils and sludges ultimately rests on the immobilization of radioactive and hazardous contaminants into a solid wasteform that is leach resistant to aqueous corrosion and other forms of degradation (such as thermal cycling and biological attack) and is highly durable. In addition, the process to immobilize the contaminants should concentrate the contaminants into the smallest volume to reduce disposal/storage and transportation costs. GTS Duratek and the Vitreous State Laboratory of The Catholic University of America have successfully demonstrated that several different waste streams can be converted into a durable, leach-resistant glass that will also lower waste volumes. In this paper, the authors discuss these successes for soils and sludges from three separate US Department of Energy sites. The sites are: the K-25 facility; the Weldon Spring site; and Fernald, Ohio.

  18. Ex-Situ Catalytic Fast Pyrolysis Technology Pathway

    SciTech Connect

    Biddy, Mary J.; Dutta, Abhijit; Jones, Susanne B.; Meyer, Pimphan A.

    2013-03-31

    In support of the Bioenergy Technologies Office, the National Renewable Energy Laboratory (NREL) and the Pacific Northwest National Laboratory (PNNL) are undertaking studies of biomass conversion technologies to hydrocarbon fuels to identify barriers and target research toward reducing conversion costs. Process designs and preliminary economic estimates for each of these pathway cases were developed using rigorous modeling tools (Aspen Plus and Chemcad). These analyses incorporated the best information available at the time of development, including data from recent pilot and bench-scale demonstrations, collaborative industrial and academic partners, and published literature and patents. This pathway case investigates converting woody biomass using ex-situ catalytic fast pyrolysis followed by upgrading to gasoline , diesel and jet range blendstocks . Technical barriers and key research needs that should be pursued for this pathway to be competitive with petroleum-derived blendstocks have been identified.

  19. In-Situ Catalytic Fast Pyrolysis Technology Pathway

    SciTech Connect

    Biddy, Mary J.; Dutta, Abhijit; Jones, Susanne B.; Meyer, Pimphan A.

    2013-03-31

    In support of the Bioenergy Technologies Office, the National Renewable Energy Laboratory (NREL) and the Pacific Northwest National Laboratory (PNNL) are undertaking studies of biomass conversion technologies to hydrocarbon fuels to identify barriers and target research toward reducing conversion costs. Process designs and preliminary economic estimates for each of these pathway cases were developed using rigorous modeling tools (Aspen Plus and Chemcad). These analyses incorporated the best information available at the time of development, including data from recent pilot and bench-scale demonstrations, collaborative industrial and academic partners, and published literature and patents. This pathway case investigates converting woody biomass using in-situ catalytic fast pyrolysis followed by upgrading to gasoline, diesel, and jet range blendstocks. Technical barriers and key research needs that should be pursued for this pathway to be competitive with petroleum-derived blendstocks have been identified.

  20. Performance of an angular flange aeroelastic wind energy converter

    SciTech Connect

    Ahmadi, G.

    1983-05-01

    ALL conventional wind turbines operate on the principles of turbomachinaries, with wind being made to flow over a set of rotating vanes. Recently, a new concept for wind energy conversion based on aeroelastic instability was introduced. It is well known that couplings between the vibration of an elastic structure and fluid stream may lead to aeroelastic instability. Energy then is transferred from the airstream into the elastic structure, which results in a destructive monotonic increase of the vibration amplitude of the structure. The failure of the Tacoma Narrows Bridge is one of the well-known examples of such a disaster. The use of an aeroelastic instability (or flutter) mechanism for constructing a wind energy converter was suggested. The theory for a torsional wind energy converter and the results of some model tests were also presented. Recently, some studies on similar types of wind energy converters using oscillating airfoils were reported. In the present study an angular flange H-section model of a torsional aeroelastic wind energy converter is constructed, and its performances under various conditions are investigated. The effects of the variations of the flange angle and the flange width on the performance of the model are studied. The weight of the pendulum is also varied, and its effects on the power coefficient of the model are investigated. It is observed that the efficiency of energy conversion decreases with an increase in wind speed. A method for possible improvement of the theoretical prediction is suggested and discussed.

  1. Microbial fuel cell energy harvesting using synchronous flyback converter

    NASA Astrophysics Data System (ADS)

    Alaraj, Muhannad; Ren, Zhiyong Jason; Park, Jae-Do

    2014-02-01

    Microbial Fuel Cells (MFCs) use biodegradable substrates, such as wastewater and marine sediments to generate electrical energy. To harvest more energy from an MFC, power electronic converters have recently been used to replace resistors or charge pumps, because they have superior controllability on MFC's operating point and higher efficiency in energy storage for different applications. Conventional diode-based energy harvesters suffer from low efficiency because of the energy losses through the diode. Replacing the diode with a MOSFET can reduce the conduction loss, but it requires an isolated gate signal to control the floating secondary MOSFET, which makes the control circuitry complex. This study presents a new MFC energy harvesting regime using a synchronous flyback converter, which implements a transformer-based harvester with much simpler configuration and improves harvesting efficiency by 37.6% compared to a diode based boost converter, from 33.5% to 46.1%. The proposed harvester was able to store 2.27 J in the output capacitor out of 4.91 J generated energy from the MFC, while the boost converter can capture 1.67 J from 4.95 J.

  2. An experimental study of SO3 dissociation as a mechanism for converting and transporting solar energy

    NASA Technical Reports Server (NTRS)

    Mccrary, J. H.; Mccrary, G. E.; Chubb, T. A.; Won, Y. S.

    1981-01-01

    The high temperature catalytic dissocation of SO3 is an important chemical process being considered in the development and application of solar-thermal energy conversion, transport, and storage systems. A facility for evaluating chemical converter-heat exchangers at temperatures to 1000 C with high flow rates of gaseous SO3 feedstock has been assembled and operated on the NMSU campus. Several quartz and metal reactors containing different catalyst configurations have been tested. Descriptions of the test facility and of the reactors are given along with a presentation and discussion of experimental results.

  3. Fuel-Flexible, Low-Emissions Catalytic Combustor for Opportunity Fuels

    SciTech Connect

    2009-11-01

    Precision Combustion, Inc. will develop a unique, fuel-flexible Rich Catalytic Lean-Burn (RCL®) injector with catalytic combustor capable of enabling ultralow-emission, lean premixed combustion of a wide range of gaseous opportunity fuels. This will broaden the range of opportunity fuels that can be utilized to include low- and ultralow-Btu gases, such as digester and blast furnace gases, and fuels containing reactive species, such as refinery, wellhead, and industrial byproduct gases.

  4. A sustainable catalytic pyrrole synthesis

    NASA Astrophysics Data System (ADS)

    Michlik, Stefan; Kempe, Rhett

    2013-02-01

    The pyrrole heterocycle is a prominent chemical motif and is found widely in natural products, drugs, catalysts and advanced materials. Here we introduce a sustainable iridium-catalysed pyrrole synthesis in which secondary alcohols and amino alcohols are deoxygenated and linked selectively via the formation of C-N and C-C bonds. Two equivalents of hydrogen gas are eliminated in the course of the reaction, and alcohols based entirely on renewable resources can be used as starting materials. The catalytic synthesis protocol tolerates a large variety of functional groups, which includes olefins, chlorides, bromides, organometallic moieties, amines and hydroxyl groups. We have developed a catalyst that operates efficiently under mild conditions.

  5. Modeling a Transient Catalytic Combustor

    NASA Technical Reports Server (NTRS)

    Tien, J. S.

    1985-01-01

    Transient model of monolith catalytic combustor presented in report done under NASA/DOE contract. Model assumes quasi-steady gas phase and thermally "thin" solid. In gas-phase treatment, several quasi-global chemical reactions assumed capable of describing CO and unburnt hydrocarbon emissions in fuel-lean operations. In steady-state computation presented, influence of selected operating and design parameters on minimum combustor length studied. When fast transient responses required, both steady and unsteady studies made to achieve meaningful compromise in design.

  6. Combined Electrolysis Catalytic Exchange (CECE)

    SciTech Connect

    Ellis, R.E.; Mills, T.K.; Rogers, M.L.

    1980-09-30

    Starting from an effort to control airborne emissions, the Mound tritium containment program has evolved to include development of the Combined Electrolysis Catalytic Exchange (CECE) process. This process separates tritiated aqueous streams into detritiated water and an enriched hydrogen stream that is suitable for use by other tritium recovery processes. Experimentation has shown that the process performs as predicted by bench-scale measurements, and that available process components exhibit acceptable resistance to damage by radiation from tritium exposure. Planned future efforts are concentrated on finalizing automatic control of the process and on developing feed treatment methods for the protection of process components.

  7. Intercell ohmic contacts for high efficiency multijunction solar converters

    NASA Technical Reports Server (NTRS)

    Zehr, S. W.; Miller, D. L.; Harris, J. S., Jr.

    1979-01-01

    The monolithic multijunction converter is an attractive approach to achieving solar/electric conversion with greater than 30% efficiency. A major technical challenge in the development of such devices is the requirement for low resistance, optically transparent intercell contacts between adjacent junctions. These contacts should transmit, without significant loss, the spectral fraction of the incident sunlight which is not absorbed and converted in the overlying junction materials. Their contact resistances must be low enough to prevent significant I to the 2d power R loss at the designed current density levels. They should also exhibit adequate thermal conductivity to prevent device overheating when subjected to the designed illumination level. Recent encouraging results for the development of such contacts are presented.

  8. Phase substitution of spare converter for a failed one of parallel phase staggered converters

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.; Wester, G. W. (Inventor)

    1977-01-01

    Failure detection and substitution of a spare module is provided in a system having a plurality of phase staggered modules connected in parallel to deliver regulated voltage from an unregulated source. Phase control signals applied to the active converter modules are applied to the spare module through NOR gates associated with and disabled by the power output of respective modules such that failure of any one enables its phase control signal to be applied to the spare module, thus controlling the spare module to operate in the phase position of the failed module. A NAND gate detects when any one active module fails and enables a gate in the spare module, thus activating the spare module.

  9. High voltage photovoltaic power converter

    DOEpatents

    Haigh, Ronald E.; Wojtczuk, Steve; Jacobson, Gerard F.; Hagans, Karla G.

    2001-01-01

    An array of independently connected photovoltaic cells on a semi-insulating substrate contains reflective coatings between the cells to enhance efficiency. A uniform, flat top laser beam profile is illuminated upon the array to produce electrical current having high voltage. An essentially wireless system includes a laser energy source being fed through optic fiber and cast upon the photovoltaic cell array to prevent stray electrical signals prior to use of the current from the array. Direct bandgap, single crystal semiconductor materials, such as GaAs, are commonly used in the array. Useful applications of the system include locations where high voltages are provided to confined spaces such as in explosive detonation, accelerators, photo cathodes and medical appliances.

  10. CATALYTIC CONVERSION OF HAZARDOUS AND TOXIC CHEMICALS: CATALYTIC HYDRODECHLORINATION OF POLYCHLORINATED PESTICIDES AND RELATED SUBSTANCES

    EPA Science Inventory

    A study has been undertaken of the catalytic conversion of chlorinated pesticides and other environmentally undesirable chlorinated materials into acceptable compounds. The results of this study show that chlorine can be catalytically removed and replaced by hydrogen to produce r...

  11. Efficiency optimization of a thermionic converter array

    NASA Technical Reports Server (NTRS)

    Kuo, Y. S.; Phillips, W. M.

    1979-01-01

    Intensive study of the outer planets of the solar system requires the use of nuclear power for electric propulsion of spacecraft. Among the power conversion devices being considered for this application are thermionic converters. This paper presents the results of computer modeling of thermionic converters to identify the major design variables and select an optimum size for each of the thermionic converters for the power conversion system under consideration. Among the variables investigated were electrical and thermal losses in electrodes, leads and heat chokes. Those elements which minimized the electrical losses tended to increase thermal losses and system weight. Overall mechanical design and relative positioning of components also had impacts on converter efficiency and the power subsystem weight. Numerical calculations were made using the computer heat transfer code SINDA coupled with electrical loss parameters. The results of the computations are presented in this paper.

  12. Rotorcraft convertible engines for the 1980s

    NASA Technical Reports Server (NTRS)

    Eisenberg, J. D.

    1982-01-01

    Two rotorcraft studies were executed. The goal was to identify attractive techniques for implementing convertible powerplants for the ABC, Folded Tilt Rotor, and X-wing type high speed, high-L/D rotorcraft; to determine the DOC and fuel savings benefits achieved thereby; and to define research required to bring these powerplants into existence by the 1990's. These studies are reviewed herein and the different methods of approach are pointed out as well as the key findings. Fan shaft engines using variable inlet guide vanes or torque converters, and turboprop powerplants appear attractive. Savings in DOC and fuel consumption of over 15 percent are predicted in some cases as a result of convertible engine use rather than using separate engines for the thrust and the shaft functions. Areas of required research are fan performance (including noise), integrated engine/rotorcraft control, torque converters, turbine design, airflow for rotorcraft torque control, bleed for lift flow, and transmissions and clutches.

  13. Waveguide mode converter and method using same

    DOEpatents

    Moeller, Charles P.

    1990-01-01

    A waveguide mode converter converts electromagnetic power being transmitted in a TE.sub.0n or a TM.sub.0n mode, where n is an integer, to an HE.sub.11 mode. The conversion process occurs in a single stage without requiring the power to pass through any intermediate modes. The converter comprises a length of circular corrugated waveguide formed in a multiperiod periodic curve. The period of the curve is selected to couple the desired modes and decouple undesired modes. The corrugation depth is selected to control the phase propagation constant, or wavenumbers, of the input and output modes, thereby preventing coherent coupling to competing modes. In one embodiment, both the period and amplitude of the curve may be selectively adjusted, thereby allowing the converter to be tuned to maximize the conversion efficiency.

  14. Metal Chlorides in Ionic Liquid Solvents Convert Sugars to 5-Hydroxymethylfurfural

    SciTech Connect

    Zhao, Haibo; Holladay, John E.; Brown, Heather M.; Zhang, Z. Conrad

    2007-06-15

    Sugars were converted to hydroxymethylfurfural (HMF) at high yield in ionic liquids without the addition of Bronsted acids. Very small amount of certain metal halides significantly reduced the fructose dehydration barrier in ionic liquids producing HMF at high yields. Most remarkably, glucose, a common sugar molecule, was selectively converted to HMF in good yield in ionic liquids containing a small amount of CrCl2. Thus CrCl2 is unique among metal chlorides tested for its effectiveness in both isomerizing glucose as well as dehydrating fructose. Only negligble amount of levulinic acid was formed in the reactions. The catalytic activity of metal chlorides for sugar conversion in ionic liquids is perhaps related to hydroxyl group of the sugar forming metal complexes with the unsaturated metal center.

  15. Molecular characterization of human and bovine endothelin converting enzyme (ECE-1).

    PubMed

    Schmidt, M; Kröger, B; Jacob, E; Seulberger, H; Subkowski, T; Otter, R; Meyer, T; Schmalzing, G; Hillen, H

    1994-12-19

    A membrane-bound protease activity that specifically converts Big endothelin-1 has been purified from bovine endothelial cells (FBHE). The enzyme was cleaved with trypsin and the peptide sequencing analysis confirmed it to be a zinc chelating metalloprotease containing the typical HEXXH (HELTH) motif. RT-PCR and cDNA screens were employed to isolate the complete cDNAs of the bovine and human enzymes. This human metalloprotease was expressed heterologously in cell culture and oocytes. The catalytic activity of the recombinant enzyme is the same as that determined for the natural enzyme. The data suggest that the characterized enzyme represents the functional human endothelin converting enzyme ECE-1. PMID:7805846

  16. ANALOG-TO-DIGITAL DATA CONVERTER

    DOEpatents

    Rodgers, G.W.; Althouse, J.E.; Anderson, D.P.; Bussey, G.R.; Minnear, L.H.

    1960-09-01

    Electrical apparatus is described, particularly useful in telemetry work, for converting analog signals into electrical pulses and recording them. An electronic editor commands the taking of signal readings at a frequency which varies according to linearity of the analog signal being converted. Readings of information signals are recorded, along with time base readings and serial numbering, if desired, on magnetic tape and the latter may be used to operate a computer or the like. Magnetic tape data may be transferred to punched cards.

  17. Electrochemical synthesis of elongated noble metal nanoparticles, such as nanowires and nanorods, on high-surface area carbon supports

    SciTech Connect

    Adzic, Radoslav; Blyznakov, Stoyan; Vukmirovic, Miomir

    2015-08-04

    Elongated noble-metal nanoparticles and methods for their manufacture are disclosed. The method involves the formation of a plurality of elongated noble-metal nanoparticles by electrochemical deposition of the noble metal on a high surface area carbon support, such as carbon nanoparticles. Prior to electrochemical deposition, the carbon support may be functionalized by oxidation, thus making the manufacturing process simple and cost-effective. The generated elongated nanoparticles are covalently bound to the carbon support and can be used directly in electrocatalysis. The process provides elongated noble-metal nanoparticles with high catalytic activities and improved durability in combination with high catalyst utilization since the nanoparticles are deposited and covalently bound to the carbon support in their final position and will not change in forming an electrode assembly.

  18. From waste to energy -- Catalytic steam gasification of broiler litter

    SciTech Connect

    Jones, J.A.; Sheth, A.C.

    1999-07-01

    In 1996, the production of broiler chickens in the US was approximately 7.60 billion head. The quantity of litter generated is enormous. In 1992, the Southeast region alone produced over five million tons of broiler litter. The litter removed from the broiler houses is rich in nutrients and often spread over land as a fertilizer. Without careful management, the associated agricultural runoff can cause severe environmental damage. With increasing broiler litter production, the implementation of alternative disposal technologies is essential to the sustainable development of the poultry industry. A process originally developed for the conversion of coals to clean gaseous fuel may provide an answer. Catalytic steam gasification utilities an alkali salt catalyst and steam to convert a carbonaceous feedstock to a gas mixture composed primarily of carbon monoxide, carbon dioxide, hydrogen, and methane. The low to medium energy content gas produced may be utilized as an energy source or chemical feedstock. Broiler litter is an attractive candidate for catalytic steam gasification due to its high potassium content. Experiments conducted in UTSI's bench-scale high-pressure fixed bed gasifier have provided data for technical and economic feasibility studies of the process. Experiments have also been performed to examine the effects of temperature, pressure, and additional catalysts on the gasification rate.

  19. Evolution of a Catalytic Mechanism.

    PubMed

    Rauwerdink, Alissa; Lunzer, Mark; Devamani, Titu; Jones, Bryan; Mooney, Joanna; Zhang, Zhi-Jun; Xu, Jian-He; Kazlauskas, Romas J; Dean, Antony M

    2016-04-01

    The means by which superfamilies of specialized enzymes arise by gene duplication and functional divergence are poorly understood. The escape from adaptive conflict hypothesis, which posits multiple copies of a gene encoding a primitive inefficient and highly promiscuous generalist ancestor, receives support from experiments showing that resurrected ancestral enzymes are indeed more substrate-promiscuous than their modern descendants. Here, we provide evidence in support of an alternative model, the innovation-amplification-divergence hypothesis, which posits a single-copied ancestor as efficient and specific as any modern enzyme. We argue that the catalytic mechanisms of plant esterases and descendent acetone cyanohydrin lyases are incompatible with each other (e.g., the reactive substrate carbonyl must bind in opposite orientations in the active site). We then show that resurrected ancestral plant esterases are as catalytically specific as modern esterases, that the ancestor of modern acetone cyanohydrin lyases was itself only very weakly promiscuous, and that improvements in lyase activity came at the expense of esterase activity. These observations support the innovation-amplification-divergence hypothesis, in which an ancestor gains a weak promiscuous activity that is improved by selection at the expense of the ancestral activity, and not the escape from adaptive conflict in which an inefficient generalist ancestral enzyme steadily loses promiscuity throughout the transition to a highly active specialized modern enzyme. PMID:26681154

  20. Substrate Orientation and Catalytic Specificity in the Action of Xanthine Oxidase: The Sequential Hydroxylation of Hypoxanthine to Uric Acid

    SciTech Connect

    Cao, Hongnan; Pauff, James M.; Hille, Russ

    2010-11-29

    Xanthine oxidase is a molybdenum-containing enzyme catalyzing the hydroxylation of a sp{sup 2}-hybridized carbon in a broad range of aromatic heterocycles and aldehydes. Crystal structures of the bovine enzyme in complex with the physiological substrate hypoxanthine at 1.8 {angstrom} resolution and the chemotherapeutic agent 6-mercaptopurine at 2.6 {angstrom} resolution have been determined, showing in each case two alternate orientations of substrate in the two active sites of the crystallographic asymmetric unit. One orientation is such that it is expected to yield hydroxylation at C-2 of substrate, yielding xanthine. The other suggests hydroxylation at C-8 to give 6,8-dihydroxypurine, a putative product not previously thought to be generated by the enzyme. Kinetic experiments demonstrate that >98% of hypoxanthine is hydroxylated at C-2 rather than C-8, indicating that the second crystallographically observed orientation is significantly less catalytically effective than the former. Theoretical calculations suggest that enzyme selectivity for the C-2 over C-8 of hypoxanthine is largely due to differences in the intrinsic reactivity of the two sites. For the orientation of hypoxanthine with C-2 proximal to the molybdenum center, the disposition of substrate in the active site is such that Arg880 and Glu802, previous shown to be catalytically important for the conversion of xanthine to uric acid, play similar roles in hydroxylation at C-2 as at C-8. Contrary to the literature, we find that 6,8-dihydroxypurine is effectively converted to uric acid by xanthine oxidase.

  1. A new generation of zirconia supported metal oxide catalysts for converting low grade renewable feedstocks to biodiesel.

    PubMed

    Kim, Manhoe; DiMaggio, Craig; Salley, Steven O; Simon Ng, K Y

    2012-08-01

    A new class of zirconia supported mixed metal oxides (ZnO-TiO(2)-Nd(2)O(3)/ZrO(2) and ZnO-SiO(2)-Yb(2)O(3)/ZrO(2)) has demonstrated the ability to convert low quality, high free fatty acid (FFA) bio-oils into biodiesel. Pelletized catalysts of ZrO(2) supported metal oxides were prepared via a sol-gel process and tested in continuous flow packed bed reactors for up to 6 months. In a single pass, while operating at mild to moderate reaction conditions, 195 °C and 300 psi, these catalysts can perform simultaneous esterification and transesterification reactions on feedstock of 33% FFA and 67% soybean oil to achieve FAME yields higher than 90%. Catalytic activity of the ZrO(2) supported metal oxide catalysts was highly dependent on the metal oxide composition. These heterogeneous catalysts will enable biodiesel manufacturers to avoid problems inherent in homogeneous processes, such as separation and washing, corrosive conditions, and excessive methanol usage. PMID:22695144

  2. 47 CFR 15.121 - Scanning receivers and frequency converters used with scanning receivers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...; replacing a plug-in semiconductor chip; or programming a semiconductor chip using special access codes or an external device, such as a personal computer. Scanning receivers, and frequency converters designed for...

  3. Design and evaluation of cellular power converter architectures

    NASA Astrophysics Data System (ADS)

    Perreault, David John

    Power electronic technology plays an important role in many energy conversion and storage applications, including machine drives, power supplies, frequency changers and UPS systems. Increases in performance and reductions in cost have been achieved through the development of higher performance power semiconductor devices and integrated control devices with increased functionality. Manufacturing techniques, however, have changed little. High power is typically achieved by paralleling multiple die in a sing!e package, producing the physical equivalent of a single large device. Consequently, both the device package and the converter in which the device is used continue to require large, complex mechanical structures, and relatively sophisticated heat transfer systems. An alternative to this approach is the use of a cellular power converter architecture, which is based upon the parallel connection of a large number of quasi-autonomous converters, called cells, each of which is designed for a fraction of the system rating. The cell rating is chosen such that single-die devices in inexpensive packages can be used, and the cell fabricated with an automated assembly process. The use of quasi-autonomous cells means that system performance is not compromised by the failure of a cell. This thesis explores the design of cellular converter architectures with the objective of achieving improvements in performance, reliability, and cost over conventional converter designs. New approaches are developed and experimentally verified for highly distributed control of cellular converters, including methods for ripple cancellation and current-sharing control. The performance of these techniques are quantified, and their dynamics are analyzed. Cell topologies suitable to the cellular architecture are investigated, and their use for systems in the 5-500 kVA range is explored. The design, construction, and experimental evaluation of a 6 kW cellular switched-mode rectifier is also addressed

  4. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly technical progress report No. 4, April--June 1993

    SciTech Connect

    Liu, Wei; Flytzani-Stephanopoulos, M.; Sarofim, A.F.; Williams, R.S.

    1993-12-31

    Elemental sulfur recovery from SO{sub 2}-containing gas stream is highly attractive as it produces a salable product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox (reduction of SO{sub 2} with coke) and Claus plant(reaction of SO{sub 2} with H{sub 2}S over catalyst). This project will investigate a cerium oxide catalyst for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for SO{sub 2} reduction by CO to elemental sulfur because its high activity and high selectivity to sulfur over COS over a wide temperature range(400--650{degrees}C). The detailed kinetic and parametric studies of SO{sub 2} reduction planned in this work over various CeO{sub 2}-formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration gas streams, The potential cost- and energy-efficiency benefits from this approach can not be overstated. A first apparent application is treatment of a regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought ``Claus-alternative`` for coal-fired power plant applications.

  5. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly technical progress report No. 6, October--December 1993

    SciTech Connect

    Liu, W.; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1993-12-31

    Elemental sulfur recovery from SO{sub 2}-containing gas stream is highly attractive as it produces a salable product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox (reduction of SO{sub 2} with coke) and Claus plant (reaction of SO{sub 2} with H{sub 2}S over catalyst). This project will investigate a cerium oxide catalyst for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for SO{sub 2} reduction by CO to elemental sulfur because its high activity and high selectivity to sulfur over COS over a wide temperature range (400--650{degree}C). The detailed kinetic and parametric studies of SO{sub 2} reduction planned in this work over various CeO{sub 2} formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration gas streams. The potential cost- and energy-efficiency benefits from this approach can not be overstated. A first apparent application is treatment of a regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought ``Claus-alternative`` for coal-fired power plant applications.

  6. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly technical progress report No. 2, October--December 1992

    SciTech Connect

    Liu, Wei; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1992-12-31

    Elemental sulfur recovery from SO{sub 2}-containing gas streams is highly attractive as it produces a saleable. Product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox (reduction of SO{sub 2} with coke) and Claus plants(reaction of SO{sub 2} with H{sub 2}S over catalyst). This project win investigate a cerium oxide catalyst for the single-stage selective reduction SO{sub 2} to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified as a superior catalyst for SO{sub 2} reduction by CO to elemental sulfur because of its high activity and high selectivity to sulfur over COS over a wide temperature range(400--650C). Kinetic and parametric studies of SO{sub 2} reduction planned over various CeO{sub 2}-formulations will provide the necessary basis for development of a simplified process, a single-stage elemental sulfur recovery scheme from variable concentration gas streams. A first apparent application is treatment of regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought ``Claus-alternative`` for coal-fired power plant applications.

  7. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly technical progress report No. 7, January--March 1994

    SciTech Connect

    Liu, Wei; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1994-12-31

    Elemental sulfur recovery from S0{sub 2}-containing gas stream is highly attractive as it produces a salable product and no waste to dispose of However, commercially available schemes are complex and involve multistage reactors, such as, most notably in the Resox (reduction of S0{sub 2} with coke) and Claus plant (reaction of S0{sub 2} with H{sub 2}S over catalyst). This project will investigate a cerium oxide catalyst for the single stage selective reduction of S0{sub 2} to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for S0{sub 2} reduction by CO to elemental sulfur because its high activity and high selectivity to sulfur over COS over a wide temperature range (400--650{degree}C). The detailed kinetic and parametric studies of S0{sub 2} reduction planned in this work over various CeO{sub 2}-formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration gas streams. The potential cost- and energy-efficiency benefits from this approach can not be overstated. A first apparent application is treatment of a regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought ``Claus-alternative`` for coal-fired power plant applications.

  8. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly technical progress report No. 3, January--March 1993

    SciTech Connect

    Liu, Wei; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1993-06-01

    Elemental sulfur recovery from SO{sub 2}-containing gas stream is highly attractive as it produces a salable product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox (reduction of SO{sub 2} with coke) and Claus plant(reaction of SO{sub 2} with H{sub 2}S over catalyst). This project will investigate a cerium oxide catalyst for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for SO{sub 2} reduction by CO to elemental sulfur because its high activity and high selectivity to sulfur over COS over a wide temperature range(400--650{degree}C). The detailed kinetic and parametric studies of SO{sub 2} reduction planned in this work over various CeO{sub 2}-formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration gas streams, The potential cost and energy-efficiency benefits from this approach can not be overstated. A first apparent application is treatment of a regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought ``Claus-alternative`` for coal-fired power plant applications.

  9. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly technical progress report No. 10, October 1994--December 1994

    SciTech Connect

    Liu, W.; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1995-03-01

    Elemental sulfur recovery from SO{sub 2}-containing gas stream is highly attractive as it produces a salable product and no waste. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox (reduction of SO{sub 2} with coke) and Claus plant (reaction of SO{sub 2} with H{sub 2}S over catalyst). This project will investigate a cerium oxide catalyst for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for SO{sub 2} reduction by CO to elemental sulfur because its high activity and high selectivity to sulfur over COS over a wide temperature range (400-650{degrees}C). The detailed kinetic and parametric studies of SO{sub 2} reduction planned in this work over various CeO{sub 2}-formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration gas streams. The potential cost- and energy-efficiency benefits from this approach cannot be overstated. A first apparent application is treatment of a regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought {open_quotes}Claus-alternative{close_quotes} for coal-fired power plant applications.

  10. Fuel elements of thermionic converters

    SciTech Connect

    Hunter, R.L.; Gontar, A.S.; Nelidov, M.V.; Nikolaev, Yu.V.; Schulepov, L.N.

    1997-01-01

    Work on thermionic nuclear power systems has been performed in Russia within the framework of the TOPAZ reactor program since the early 1960s. In the TOPAZ in-core thermionic convertor reactor design, the fuel element`s cladding is also the thermionic convertor`s emitter. Deformation of the emitter can lead to short-circuiting and is the primary cause of premature TRC failure. Such deformation can be the result of fuel swelling, thermocycling, or increased unilateral pressure on the emitter due to the release of gaseous fission products. Much of the work on TRCs has concentrated on preventing or mitigating emitter deformation by improving the following materials and structures: nuclear fuel; emitter materials; electrical insulators; moderator and reflector materials; and gas-exhaust device. In addition, considerable effort has been directed toward the development of experimental techniques that accurately mimic operational conditions and toward the creation of analytical and numerical models that allow operational conditions and behavior to be predicted without the expense and time demands of in-pile tests. New and modified materials and structures for the cores of thermionic NPSs and new fabrication processes for the materials have ensured the possibility of creating thermionic NPSs for a wide range of powers, from tens to several hundreds of kilowatts, with life spans of 5 to 10 years.

  11. Effect of ion implantation on the catalytic properties of a surface

    SciTech Connect

    Poplavskii, V.V.; Novikov, G.I.; Ratnikov, E.V.

    1986-10-20

    Relatively few studies have been made of the effect of ion implantation on the catalytic properties of materials. The surveys by Grant and Wolf in particular generalized earlier studies. There are also several original investigations. Here, two heterogeneous catalytic systems were examined: (a) catalytic reactions between gaseous substances on solid catalysts with a modified surface; electrocatalytic reactions in solutions on the surface of catalyst-electrodes. The studies showed that specific effects due to the chemical properties of the implanted elements are of interest in catalysis along with purely physical effects such as enlargement, texturing and pickling of the surface.

  12. FEASIBILITY OF BURNING COAL IN CATALYTIC COMBUSTORS

    EPA Science Inventory

    The report gives results of a study, showing that pulverized coal can be burned in a catalytic combustor. Pulverized coal combustion in catalytic beds is markedly different from gaseous fuel combustion. Gas combustion gives uniform bed temperatures and reaction rates over the ent...

  13. ZVS Full-Bridge Based DC-DC Converter with Linear Voltage Gain According to Duty Cycle

    NASA Astrophysics Data System (ADS)

    Do, Hyun-Lark

    2013-09-01

    This paper presents a zero-voltage-switching (ZVS) full-bridge based DC-DC converter with linear voltage gain according to duty cycle. The proposed converter is based on an asymmetrical pulse-width-modulation (APWM) full-bridge converter which has various advantages over other converters. However, it has some drawbacks such as limited maximum duty cycle to 0.5 and narrow input range. The proposed converter overcomes these problems. The duty cycle is not limited and input voltage range is wide. Also, the ZVS operation of all power switches is achieved. Therefore, switching losses are significantly reduced and high-efficiency is obtained. Steady-state analysis and experimental results for the proposed converter are presented to validate the feasibility and the performance of the proposed converter.

  14. A polarization converter array using a twisted-azimuthal liquid crystal in cylindrical polymer cavities.

    PubMed

    Wang, Xiahui; Xu, Miao; Ren, Hongwen; Wang, Qionghua

    2013-07-01

    We report a simple method to prepare an array of polarization converters using a twisted-azimuthal nematic liquid crystal (NLC) in cylindrical polymer cavities. When a NLC is filled in a cylindrical polymer cavity, LC in the cavity presents concentrically circular orientations. By treating LC on one side of the cavity with homogeneous alignment, a twisted-azimuthal texture is formed. Such a LC texture can convert a linear polarization light to either radial or azimuthal polarization light depending on the polarization direction of the incident light. The LC surface on the other side of the cavity is convex, so the light after passing through the cavity can be focused as well. The LC texture can be fixed firmly using polymer network. In comparison with previous polarization converters, our polarization converter has the merits of individually miniature size, array of pattern, and lens character. Our polarization converter array has potential applications in tight focusing, imaging, and material processing. PMID:23842407

  15. Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

    DOEpatents

    Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

    2014-09-09

    A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

  16. Method of fabricating a catalytic structure

    DOEpatents

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2009-09-22

    A precursor to a catalytic structure comprising zinc oxide and copper oxide. The zinc oxide has a sheet-like morphology or a spherical morphology and the copper oxide comprises particles of copper oxide. The copper oxide is reduced to copper, producing the catalytic structure. The catalytic structure is fabricated by a hydrothermal process. A reaction mixture comprising a zinc salt, a copper salt, a hydroxyl ion source, and a structure-directing agent is formed. The reaction mixture is heated under confined volume conditions to produce the precursor. The copper oxide in the precursor is reduced to copper. A method of hydrogenating a carbon oxide using the catalytic structure is also disclosed, as is a system that includes the catalytic structure.

  17. Diesel engine catalytic combustor system. [aircraft engines

    NASA Technical Reports Server (NTRS)

    Ream, L. W. (Inventor)

    1984-01-01

    A low compression turbocharged diesel engine is provided in which the turbocharger can be operated independently of the engine to power auxiliary equipment. Fuel and air are burned in a catalytic combustor to drive the turbine wheel of turbine section which is initially caused to rotate by starter motor. By opening a flapper value, compressed air from the blower section is directed to catalytic combustor when it is heated and expanded, serving to drive the turbine wheel and also to heat the catalytic element. To start, engine valve is closed, combustion is terminated in catalytic combustor, and the valve is then opened to utilize air from the blower for the air driven motor. When the engine starts, the constituents in its exhaust gas react in the catalytic element and the heat generated provides additional energy for the turbine section.

  18. Catalytic ignition of hydrogen/oxygen

    NASA Technical Reports Server (NTRS)

    Green, James M.; Zurawski, Robert L.

    1988-01-01

    An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen. Shell 405 granular catalyst and a unique monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant inlet temperature, and back pressure were varied parametrically in testing to determine the operational limits of a catalytic igniter. The test results showed that the gaseous hydrogen/oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. The results of the experimental program and the established operational limits for a catalytic igniter using both the granular and monolithic catalysts are presented. The capabilities of a facility constructed to conduct the igniter testing and the advantages of a catalytic igniter over other ignition systems for gaseous hydrogen and oxygen are also discussed.

  19. Catalytic ignition of hydrogen and oxygen propellants

    NASA Technical Reports Server (NTRS)

    Zurawski, Robert L.; Green, James M.

    1988-01-01

    An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen propellants. Shell 405 granular catalyst and a monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant temperature, and back pressure were varied parametrically in testing to determine the operational limits of the catalytic igniter. The test results show that the gaseous hydrogen and oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. A cyclic life of nearly 2000, 2 sec pulses at nominal operating conditions was demonstrated with the catalytic igniter. The results of the experimental program and the established operational limits for a catalytic igniter using the Shell 405 catalysts are presented.

  20. Catalytic ignition of hydrogen and oxygen propellants

    NASA Technical Reports Server (NTRS)

    Zurawski, Robert L.; Green, James M.

    1988-01-01

    An experimental program was conducted to evaluate the catalytic ignition of gaseous hydrogen and oxygen propellants. Shell 405 granular catalyst and a monolithic sponge catalyst were tested. Mixture ratio, mass flow rate, propellant temperature, and back pressure were varied parametrically in testing to determine the operational limits of the catalytic igniter. The test results show that the gaseous hydrogen and oxygen propellant combination can be ignited catalytically using Shell 405 catalyst over a wide range of mixture ratios, mass flow rates, and propellant injection temperatures. These operating conditions must be optimized to ensure reliable ignition for an extended period of time. A cyclic life of nearly 2000, 2 sec pulses at nominal operating conditions was demonstrated with the catalytic igniter. The results of the experimental program and the established operational limits for a catalytic igniter using the Shell 405 catalyst are presented.