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Sample records for catalytic membranes final

  1. Catalytic carbon membranes for hydrogen production. Final report

    SciTech Connect

    Damle, A.S.; Gangwal, S.K.

    1992-01-01

    Commercial carbon composite microfiltration membranes may be modified for gas separation applications by providing a gas separation layer with pores in the 1- to 10-nm range. Several organic polymeric precursors and techniques for depositing a suitable layer were investigated in this project. The in situ polymerization technique was found to be the most promising, and pure component permeation tests with membrane samples prepared with this technique indicated Knudsen diffusion behavior. The gas separation factors obtained by mixed-gas permeation tests were found to depend strongly on gas temperature and pressure indicating significant viscous flow at high-pressure conditions. The modified membranes were used to carry out simultaneous water gas shift reaction and product hydrogen separation. These tests indicated increasing CO conversions with increasing hydrogen separation. A simple process model was developed to simulate a catalytic membrane reactor. A number of simulations were carried out to identify operating conditions leading to product hydrogen concentrations over 90 percent. (VC)

  2. Development of high temperature catalytic membrane reactors. Final report

    SciTech Connect

    Gallaher, G.; Gerdes, T.; Gregg, R.

    1992-02-28

    Early efforts in 1992 were focused on relocating the membrane reactor system from Alcoa Separation Technology, Inc.`s Warrendale, PA facility to laboratory space at the University of Pittsburgh Applied Research Center (UPARC) in Harmarville, PA following the divestiture of Alcoa Separations to US Filter, Inc. Reconstruction was completed in March, 1992, at which time the reactor was returned to ethylbenzene dehydrogenation service. Efforts on ethylbenzene dehydrogenation to styrene focused on optimizing hybrid reactor performance relative to packed bed operation. Following this, the reactor system was converted to isobutane dehydrogenation. Experimentation on isobutane dehydrogenation focused on design of an inert reactor, evaluation of commercial light alkane dehydrogenation catalysts, and modeling of membrane reactor performance relative to the performance of a packed bed reactor. This report summarizes the effort in 1992 on the development of ceramic membranes as dehydrogenation reactors. In addition, outside interactions on behalf of this investigation are discussed.

  3. 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.

  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. 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.

  6. 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.

  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 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.

  9. Novel Catalytic Membrane Reactors

    SciTech Connect

    2009-02-01

    This factsheet describes a research project that will focus on the development and application of nonporous high gas flux perfluoro membranes with high temperature rating and excellent chemical resistance.

  10. Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils. Final Report

    SciTech Connect

    George W. Huber; Upadhye, Aniruddha A.; Ford, David M.; Bhatia, Surita R.; Badger, Phillip C.

    2012-10-19

    This University of Massachusetts, Amherst project, "Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils" started on 1st February 2009 and finished on August 31st 2011. The project consisted following tasks: Task 1.0: Char Removal by Membrane Separation Technology The presence of char particles in the bio-oil causes problems in storage and end-use. Currently there is no well-established technology to remove char particles less than 10 micron in size. This study focused on the application of a liquid-phase microfiltration process to remove char particles from bio-oil down to slightly sub-micron levels. Tubular ceramic membranes of nominal pore sizes 0.5 and 0.8m were employed to carry out the microfiltration, which was conducted in the cross-flow mode at temperatures ranging from 38 to 45 C and at three different trans-membrane pressures varying from 1 to 3 bars. The results demonstrated the removal of the major quantity of char particles with a significant reduction in overall ash content of the bio-oil. The results clearly showed that the cake formation mechanism of fouling is predominant in this process. Task 2.0 Acid Removal by Membrane Separation Technology The feasibility of removing small organic acids from the aqueous fraction of fast pyrolysis bio-oils using nanofiltration (NF) and reverse osmosis (RO) membranes was studied. Experiments were carried out with a single solute solutions of acetic acid and glucose, binary solute solutions containing both acetic acid and glucose, and a model aqueous fraction of bio-oil (AFBO). Retention factors above 90% for glucose and below 0% for acetic acid were observed at feed pressures near 40 bar for single and binary solutions, so that their separation in the model AFBO was expected to be feasible. However, all of the membranes were irreversibly damaged when experiments were conducted with the model AFBO due to the presence of guaiacol in the feed solution. Experiments

  11. Enzyme catalytic membrane based on a hybrid mesoporous membrane.

    PubMed

    Fu, Wensheng; Yamaguchi, Akira; Kaneda, Hideaki; Teramae, Norio

    2008-02-21

    Immobilization of glucose oxidase (GOD) within a hybrid mesoporous membrane with 12 nm pore diameter was successfully achieved, resulting in catalytically high efficiency during flow of a glucose solution across the membrane. PMID:18253526

  12. Mass transfer in composite catalytic membranes

    SciTech Connect

    Langhendries, G.; Claessens, R.; Baron, G.V.

    1996-12-31

    The partial oxidation of cyclohexane was studied in a composite polymer-zeolite catalytic membrane reactor. In a first step the equilibrium and mass transfer properties (swelling, diffusion and sorption) of dense composite membranes were examined. The swelling behavior of the crosslinked poly(dimethylsiloxane) network was determined for several solvents and related to the differences between the Hildebrand solubility parameters of solvent and polymer. Time lag experiments, which enable us to measure simultaneously diffusion and partition coefficients, were carried out on a dense poly(dimethylsiloxane) membrane. A mathematical model describing the mass transfer behavior of these catalytic membranes was derived and validated with experimental data. Mass transfer through composite catalytic membranes can be predicted using the properties of pure catalyst and polymer material, and a single tortuosity factor. 9 refs., 5 figs., 4 tabs.

  13. Catalytic carbon membranes for hydrogen production

    SciTech Connect

    Damle, A.S.; Gangwal, S.K.

    1992-01-01

    Commercial carbon composite microfiltration membranes may be modified for gas separation applications by providing a gas separation layer with pores in the 1- to 10-nm range. Several organic polymeric precursors and techniques for depositing a suitable layer were investigated in this project. The in situ polymerization technique was found to be the most promising, and pure component permeation tests with membrane samples prepared with this technique indicated Knudsen diffusion behavior. The gas separation factors obtained by mixed-gas permeation tests were found to depend strongly on gas temperature and pressure indicating significant viscous flow at high-pressure conditions. The modified membranes were used to carry out simultaneous water gas shift reaction and product hydrogen separation. These tests indicated increasing CO conversions with increasing hydrogen separation. A simple process model was developed to simulate a catalytic membrane reactor. A number of simulations were carried out to identify operating conditions leading to product hydrogen concentrations over 90 percent. (VC)

  14. Mesoporous catalysts, supports and catalytic membranes based on MCM-41. Final report for the period January 15,2000 - January 14, 2001

    SciTech Connect

    Haller, Gary L.

    2001-07-01

    The research had two objectives: to understand the effect of pore size on the chemistry and activity of active sites, and to investigate both the pore size and anchoring effect of Me-MCM-41 on Pt clusters (where Me is a metal incorporated in silica-based MCM-41). The focus is not on the effect of pore size on transport of reactants and products, but on how the local radius of curvature might affect the properties of a foreign ion embedded in a silicon wall that acts as a catalytic site or anchor for the catalytic site. The mesoporous molecular sieve, MCM-41, allows the variation of pore size with constant composition and pore geometry so these new materials allow this scientific question to be addressed for the first time. For the anchoring effect, concentration was on Sn-MCM-41 to prepare Pt/Sn-MCM-41 catalysts, by characterizing these and by testing them with probe reforming reactions (dehydrogenation, isomerization and aromatization). Although this is a final report on activity January 15, 2000 - January 14, 2001, this was a continuation of work initiated in the three-year grant period January 15, 1997 - January 14, 2000, so the summary of progress for these three years is appended for completeness.

  15. Catalytic coal liquefaction. Final report

    SciTech Connect

    Weller, S W

    1981-01-01

    Monolith catalysts of MoO/sub 3/-CoO-Al/sub 2/O/sub 3/ were prepared and tested for coal liquefaction in a stirred autoclave. In general, the monolith catalysts were not as good as particulate catalysts prepared on Corning alumina supports. Measurement of O/sub 2/ chemisorption and BET surface area has been made on a series of Co/Mo/Al/sub 2/O/sub 3/ catalysts obtained from PETC. The catalysts were derived from Cyanamid 1442A and had been tested for coal liquefaction in batch autoclaves and continuous flow units. MoO/sub 3/-Al/sub 2/O/sub 3/ catalysts over the loading range 3.9 to 14.9 wt % MoO/sub 3/ have been studied with respect to BET surface (before and after reduction), O/sub 2/ chemisorption at -78/sup 0/C, redox behavior at 500/sup 0/C, and activity for cyclohexane dehydrogenation at 500/sup 0/C. In connection with the fate of tin catalysts during coal liquefaction, calculations have been made of the relative thermodynamic stability of SnCl/sub 2/, Sn, SnO/sub 2/, and SnS in the presence of H/sub 2/, HCl, H/sub 2/S and H/sub 2/O. Ferrous sulfate dispersed in methylnaphthalene has been shown to be reduced to ferrous sulfide under typical coal hydroliquefaction conditions (1 hour, 450/sup 0/C, 1000 psi initial p/sub H/sub 2//). This suggests that ferrous sulfide may be the common catalytic ingredient when either (a) ferrous sulfate impregnated on powdered coal, or (b) finely divided iron pyrite is used as the catalyst. Old research on impregnated ferrous sulfate, impregnated ferrous halides, and pyrite is consistent with this assumption. Eight Co/Mo/Al/sub 2/O/sub 3/ catalysts from commercial suppliers, along with SnCl/sub 2/, have been studied for the hydrotreating of 1-methylnaphthalene (1-MN) in a stirred autoclave at 450 and 500/sup 0/C.

  16. Carbogenic molecular sieves for reaction and separation by design: A novel approach to shape selective super base, super acid and catalytic membranes. Final report

    SciTech Connect

    Foley, Henry C.

    2002-03-18

    This report details the findings of three years of research plus one year of a no-cost extension. Primary results are the work with supported nanoporous carbon membranes for separation and reaction as well as with cesium-nanoporous carbon catalysts. The work resulted in 17 plus 2 papers (2 are in progress) and partial or full support for five Ph.D. students. Two patents were filed based on this research.

  17. Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

    DOEpatents

    Schwartz, Michael; White, James H.; Sammels, Anthony F.

    2000-01-01

    This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

  18. Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

    DOEpatents

    Schwartz, Michael; White, James H.; Sammells, Anthony F.

    2005-09-27

    This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

  19. 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.

  20. Catalytic membrane reactor for conversion of syngas to liquid hydrocarbons

    SciTech Connect

    Khassin, A.A.

    2005-07-01

    Plug-through catalytically-active contractor membranes can combine high permeability ({gt} 20 m Darcy), high mechanical strength ({gt} 20 kg cm{sup -2}) and high heat-conductivity ({gt} 4 W(mK){sup -1}). Therefore, it provides isothermicity and low pressure drop. The intense mass-transfer within transport pores, high specific area of these pores and small distances between two adjacent transport pores weaken the mass-transfer constraints. Using the PCM one can achieve high space time yield of hydrocarbons and high selectivity towards heavy hydrocarbons and olefins. These advantages allow supposing the effective usage of the PCM catalytic membrane reactors in Fischer-Tropsch synthesis. Also the same approach could be efficient for some other multiphase catalytic processes, like hydrogenation of the unsaturated fatty acids. 5 figs.

  1. Catalytic membrane reactor for water and wastewater treatment

    NASA Astrophysics Data System (ADS)

    Heng, Samuel

    A double membrane reactor was fabricated and assessed for continuous treatment of water containing organic contaminants by ozonation. This innovative reactor consisted of a zeolite membrane prepared on the inner surface of a porous a-alumina support, which served as water selective extractor and active contactor, and a porous stainless membrane which was the ozone gas diffuser. The coupling of membrane separation and chemical oxidation was found to be highly beneficial to both processes. The total organic carbon (TOC) removal rate at the retentate was enhanced by up to 2.2 times, as compared to membrane ozonation. Simultaneously, clean water (< 2 mg C.L-1 ) was consistently produced on the permeate side, using a feed solution containing up to 1000 mg C.L-1, while the retentate was concentrated and treated. Most significantly, the addition of an adsorbing material, as a bed or a coated layer, onto the pores of the membrane support, was shown to further enhance TOC degradation, permeated TOC concentration, permeate flux, and moreover, ozone yield. The achievements of this project included: (1) The development of a novel low-temperature zeolite membrane activation method that generates consistently high quality membranes (i.e. high reproducibility and fewer defects). (2) The demonstration that gamma-alumina and gamma-alumina supported catalysts do not have significant activity and that the TOC removal enhancement usually observed during catalytic ozonation was due primarily to the contribution of adsorption and metal leaching. Thermogravimetric analysis (TGA) and elemental analysis (EA) of the spent catalyst showed that, during catalytic ozonation, oxygenated by-products of increased adsorbability were concentrated onto the gamma-alumina contactor, and were subsequently degraded. (3) The development of a method for coating high surface area gamma-alumina layers onto the grains of zeolite membrane support used as the active membrane contactor.

  2. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, James H.; Schwartz, Michael; Sammells, Anthony F.

    2000-01-01

    Mixed electron- and proton-conducting metal oxide materials are provided. These materials are useful in fabrication of membranes for use in catalytic membrane reactions, particularly for promoting dehydrogenation of hydrocarbons, oligomerization of hydrocarbons and for the decomposition of hydrogen-containing gases. Membrane materials are perovskite compounds of the formula: AB.sub.1-x B'.sub.x O.sub.3-y where A=Ca, Sr, or Ba; B=Ce, Tb, Pr or Th; B'=Ti, V, Cr, Mn, Fe, Co, Ni or Cu; 0.2

  3. Membranes for corrosive oxidations. Final CRADA report.

    SciTech Connect

    Snyder, S. W.; Energy Systems

    2010-02-01

    The objective of this project is to develop porous hydrophilic membranes that are highly resistant to oxidative and corrosive conditions and to deploy them for recovery and purification of high tonnage chemicals such as hydrogen peroxide and other oxychemicals. The research team patented a process for membrane-based separation of hydrogen peroxide (US Patent No. 5,662,878). The process is based on using a hydrophilic membrane to separate hydrogen peroxide from the organic working solution. To enable this process, a new method for producing hydrophilic membrane materials (Patent No.6,464,880) was reported. We investigated methods of producing these hydrophilic materials and evaluated separations performance in comparison to membrane stability. It was determined that at the required membrane flux, membrane stability was not sufficient to design a commercial process. This work was published (Hestekin et al., J. Membrane Science 2006). To meet the performance needs of the process, we developed a membrane contactor method to extract the hydrogen peroxide, then we surveyed several commercial and pre-commercial membrane materials. We identified pre-commercial hydrophilic membranes with the required selectivity, flux, and stability to meet the needs of the process. In addition, we invented a novel reaction/separations format that greatly increases the performance of the process. To test the performance of the membranes and the new formats we procured and integrated reactor/membrane separations unit that enables controlled mixing, flow, temperature control, pressure control, and sampling. The results were used to file a US non-provisional patent application (ANL-INV 03-12). Hydrogen peroxide is widely used in pulp and paper applications, environmental treatment, and other industries. Virtually all hydrogen peroxide production is now based on a process featuring catalytic hydrogenation followed by auto-oxidation of suitable organic carrier molecules. This process has several

  4. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, James H.; Schwartz, Michael; Sammells, Anthony F.

    1998-01-01

    This invention provides catalytic proton and electron mediating membranes useful in catalytic reactors. The membranes have an oxidation and a reduction surface and comprise a single-phase mixed metal oxide material of the formula: AB.sub.1-x B'.sub.x O.sub.3-y wherein A is selected from Ca, Sr or Ba ions; B is selected from Ce, Tb, Pr, or Th ions; B' is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Ga, or In ions, or combinations thereof; and x is greater than or equal to 0.02 and less than or equal to 0.5. The membranes can further comprise a catalyst on either the oxidation or reduction surface, or both. Membranes include those which are fabricated-by combining powders of metal oxides or metal carbonates of metal A ion, metal B ion and metal B' ion such that the stoichiometric ratio A:B:B' is 1:1-x:x where 0.2.ltoreq..times.0.5, repeatedly calcining and milling the combined powders until a single-phase material is obtained and pressing and sintering the singlephase material to obtain a membrane.

  5. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, J.H.; Schwartz, M.; Sammells, A.F.

    1998-10-13

    This invention provides catalytic proton and electron mediating membranes useful in catalytic reactors. The membranes have an oxidation and a reduction surface and comprise a single-phase mixed metal oxide material of the formula: AB{sub 1{minus}x}B{prime}{sub x}O{sub 3{minus}y} wherein A is selected from Ca, Sr or Ba ions; B is selected from Ce, Tb, Pr, or Th ions; B{prime} is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Ga, or In ions, or combinations thereof; and x is greater than or equal to 0.02 and less than or equal to 0.5. The membranes can further comprise a catalyst on either the oxidation or reduction surface, or both. Membranes include those which are fabricated by combining powders of metal oxides or metal carbonates of metal A ion, metal B ion and metal B{prime} ion such that the stoichiometric ratio A:B:B{prime} is 1:1{minus}x:x where 0.2{<=}{times}0.5, repeatedly calcining and milling the combined powders until a single-phase material is obtained and pressing and sintering the single phase material to obtain a membrane. 6 figs.

  6. 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.

  7. Solid state proton and electron mediating membrane and use in catalytic membrane reactors

    DOEpatents

    White, James H.; Schwartz, Michael; Sammells, Anthony F.

    2001-01-01

    Mixed electron- and proton-conducting metal oxide materials are provided. These materials are useful in fabrication of membranes for use in catalytic membrane reactions, particularly for promoting dehydrogenation of hydrocarbons, oligomerization of hydrocarbons and for the decomposition of hydrogen-containing gases. Membrane materials are perovskite compounds of the formula: AB.sub.1-x B'.sub.x O.sub.3-y where A=Ca, Sr, or Ba; B=Ce, Tb, Pr or Th; B'=Ti, V, Cr, Mn, Fe, Co, Ni or Cu; 0.2.ltoreq.x.ltoreq.0.5, and y is a number sufficient to neutralize the charge in the mixed metal oxide material.

  8. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M; Kromer, Brian R; Litwin, Michael M; Rosen, Lee J; Christie, Gervase Maxwell; Wilson, Jamie R; Kosowski, Lawrence W; Robinson, Charles

    2014-01-07

    A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.

  9. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  10. Ceramic membranes for catalytic membrane reactors with high ionic conductivities and low expansion properties

    DOEpatents

    Mackay, Richard; Sammells, Anthony F.

    2000-01-01

    Ceramics of the composition: Ln.sub.x Sr.sub.2-x-y Ca.sub.y B.sub.z M.sub.2-z O.sub.5+.delta. where Ln is an element selected from the fblock lanthanide elements and yttrium or mixtures thereof; B is an element selected from Al, Ga, In or mixtures thereof; M is a d-block transition element of mixtures thereof; 0.01.ltoreq.x.ltoreq.1.0; 0.01.ltoreq.y.ltoreq.0.7; 0.01.ltoreq.z.ltoreq.1.0 and .delta. is a number that varies to maintain charge neutrality are provided. These ceramics are useful in ceramic membranes and exhibit high ionic conductivity, high chemical stability under catalytic membrane reactor conditions and low coefficients of expansion. The materials of the invention are particularly useful in producing synthesis gas.

  11. A mesoporous catalytic membrane architecture for lithium-oxygen battery systems.

    PubMed

    Ryu, Won-Hee; Gittleson, Forrest S; Schwab, Mark; Goh, Tenghooi; Taylor, André D

    2015-01-14

    Controlling the mesoscale geometric configuration of catalysts on the oxygen electrode is an effective strategy to achieve high reversibility and efficiency in Li-O2 batteries. Here we introduce a new Li-O2 cell architecture that employs a catalytic polymer-based membrane between the oxygen electrode and the separator. The catalytic membrane was prepared by immobilization of Pd nanoparticles on a polyacrylonitrile (PAN) nanofiber membrane and is adjacent to a carbon nanotube electrode loaded with Ru nanoparticles. During oxide product formation, the insulating PAN polymer scaffold restricts direct electron transfer to the Pd catalyst particles and prevents the direct blockage of Pd catalytic sites. The modified Li-O2 battery with a catalytic membrane showed a stable cyclability for 60 cycles with a capacity of 1000 mAh/g and a reduced degree of polarization (∼ 0.3 V) compared to cells without a catalytic membrane. We demonstrate the effects of a catalytic membrane on the reaction characteristics associated with morphological and structural features of the discharge products via detailed ex situ characterization. PMID:25546408

  12. Cryogenic methane separation/catalytic hydrogasification process analysis. Final report

    SciTech Connect

    Cassano, A.A.; Hilton, M.F.; Li, T.C.; Tsao, T.R.

    1980-02-14

    The objective of this program was to recommend the most attractive combinations of acid gas removal methane separation systems for the Exxon Catalytic Coal Gasification (CCG) and the Rockwell Hydrogasification process currently undergoing development supported by DOE. The program was comprised of the following tasks. Screening to define the most promising integration scheme for each gasification process; development of a process flowsheet, heat and material balance, P and ID, equipment specification, utility summary, and plot plan for the process combination selected; and preparation of detailed economic and final report. The results of the study are documented in this report. The evaluations were performed using data supplied by the prime coal gasification contractors and the vendors of proprietary acid gas removal processes. This information, combined with Air Products' in-house capabilities in acid gas and cryogenic separation processses, was used to develop process designs and cost estimates for each integrated system. The design based and economic criteria employed in the study are described.

  13. Esterification of acidified oil with methanol by SPES/PES catalytic membrane.

    PubMed

    Shi, Wenying; He, Benqiao; Li, Jianxin

    2011-05-01

    A sulfonated polyethersulfone (SPES)/polyethersulfone (PES) blend catalytic membrane was prepared and used as a heterogeneous catalyst in the esterification of the acidified oil (acid value 153 mg KOH/g) with methanol for producing biodiesel. The results showed that the free fatty acids conversion reached 97.6% using SPES/PES catalytic membrane under the optimal esterification conditions. Meanwhile, the SPES/PES membrane with 20.3% degree of sulfonation showed a good catalytic stability. A pseudo-homogeneous kinetic model was established. The results indicated that the reaction rate constant increased with increasing methanol/acidified oil molar ratio, the loading of catalytic membrane and reaction temperature. The reaction order was 2 and the activation energy decreased from 74.65 to 21.07 kJ/mol with increasing catalytic membrane loading from 0 to 0.135 meq/g(oil). It implies that the esterification is not diffusively controlled but kinetically controlled. The predicted results were in good agreement with the experimental data. PMID:20951577

  14. Catalytic membranes for CO oxidation in fuel cells

    DOEpatents

    Sandi-Tapia, Giselle; Carrado Gregar, Kathleen; Kizilel, Riza

    2010-06-08

    A hydrogen permeable membrane, which includes a polymer stable at temperatures of about 200 C having clay impregnated with Pt or Au or Ru or Pd particles or mixtures thereof with average diameters of less than about 10 nanometers (nms) is disclosed. The membranes are useful in fuel cells or any device which requires hydrogen to be separated from carbon monoxide.

  15. Mn oxide coated catalytic membranes for a hybrid ozonation-membrane filtration: comparison of Ti, Fe and Mn oxide coated membranes for water quality.

    PubMed

    Byun, S; Davies, S H; Alpatova, A L; Corneal, L M; Baumann, M J; Tarabara, V V; Masten, S J

    2011-01-01

    In this study the performance of catalytic membranes in a hybrid ozonation-ceramic membrane filtration system was investigated. The catalytic membranes were produced by coating commercial ceramic ultrafiltration membranes with manganese or iron oxide nanoparticles using a layer-by-layer self-assembly technique. A commercial membrane with a titanium oxide filtration layer was also evaluated. The performance of the coated and uncoated membranes was evaluated using water from a borderline eutrophic lake. The permeate flux and removal of the organic matter was found to depend on the type of the metal oxide present on the membrane surface. The performance of the manganese oxide coated membrane was superior to that of the other membranes tested, showing the fastest recovery in permeate flux when ozone was applied and the greatest reduction in the total organic carbon (TOC) in the permeate. The removal of trihalomethanes (THMs) and haloacetic acids (HAAs) precursors using the membrane coated 20 times with manganese oxide nanoparticles was significantly better than that for the membranes coated with 30 or 40 times with manganese oxide nanoparticles or 40 times with iron oxide nanoparticles. PMID:20822791

  16. Long life catalytic membrane reactors for spontaneous conversion of natural gas to synthesis gas

    SciTech Connect

    Schwartz, M., White, J., Deych, S., Millard, J., Myers, M., Sammells, A.

    1997-10-01

    This program is focusing on the development of mixed ionic and electronic conducting materials based on the brown millerite structure for use in catalytic membrane reactors (CMRs). These CMRs are being evaluated for promoting the spontaneous and highly selective oxidative reforming of carbon dioxide / natural gas mixtures to synthesis gas.

  17. Modification of tubular ceramic membranes with carbon nanotubes using catalytic chemical vapor deposition.

    PubMed

    Tran, Duc Trung; Thieffry, Guillemette; Jacob, Matthieu; Batiot-Dupeyrat, Catherine; Teychene, Benoit

    2015-01-01

    In this study, carbon nanotubes (CNTs) were successfully grown on tubular ceramic membranes using the catalytic chemical vapor deposition (CCVD) method. CNTs were synthesized at 650°C for 3-6 h under a 120 mL min(-1) flow of C2H6 on ceramic membranes impregnated with iron salt. The synthesis procedure was beforehand optimized in terms of catalyst amount, impregnation duration and reaction temperature, using small pieces of tubular ceramic membranes. The yield, size and structure of the CNTs produced were characterized using thermogravimetric analysis and microscopic imaging techniques. Afterwards, preliminary filtration tests with alginate and phenol were performed on two modified tubular membranes. The results indicate that the addition of CNTs on the membrane material increased the permeability of ceramic membrane and its ability to reject alginate and adsorb phenol, yet decreased its fouling resistance. PMID:26465312

  18. Production of an ion-exchange membrane-catalytic electrode bonded material for electrolytic cells

    NASA Technical Reports Server (NTRS)

    Takenaka, H.; Torikai, E.

    1986-01-01

    A good bond is achieved by placing a metal salt in solution on one side of a membrane and a reducing agent on the other side so that the reducing agent penetrates the membrane and reduces the metal. Thus, a solution containing Pt, Rh, etc., is placed on one side of the membrane and a reducing agent such as NaBH, is placed on the other side. The bonded metal layer obtained is superior in catalytic activity and is suitable as an electrode in a cell such as for solid polymer electrolyte water electrolysis.

  19. Gas separation with glass membranes. Final report

    SciTech Connect

    Roberts, D.L.; Abraham, L.C.; Blum, Y.; Way, J.D.

    1992-05-01

    The Department of Energy (DOE) is seeking to develop high temperature, high pressure inorganic membrane technology to perform a variety of gas separation processes to improve the efficiency and economics of advanced power generation systems such as direct coal-fueled turbines (DCFT) and the integrated gasification combined cycle process (IGCC). The temperatures encountered in these power generation systems are far above the temperature range for organic membrane materials. Inorganic materials such as ceramics are therefore the most likely membrane materials for use at high temperatures. This project focussed on silica glass fiber membranes made by PPG Industries (Pittsburgh, PA). The goals were both experimental and theoretical. The first objective was to develop a rational theory for the performance of these membranes. With existing theories as a starting point, a new theory was devised to explain the unusual ``molecular sieving`` behavior exhibited by these glass membranes. An apparatus was then devised for making permeation performance measurements at conditions of interest to DOE (temperatures to 2000{degrees}F; pressures to 1000 psia). With this apparatus, gas mixtures could be made typical of coal combustion or coal gasification processes, these gases could be passed into a membrane test cell, and the separation performance determined. Data were obtained for H{sub 2}/CO,N{sub 2}/CO{sub 2}, 0{sub 2}/N{sub 2}, and NH{sub 3}/N{sub 2} mixtures and for a variety of pure component gases (He, H{sub 2}, CO{sub 2}, N{sub 2}, CO, NH{sub 3}). The most challenging part of the project turned out to be the sealing of the membrane at high temperatures and pressures. The report concludes with an overview of the practical potential of these membranes and of inorganic membranes in general of DOE and other applications.

  20. [Enhancement of coal liquefaction efficiency with ceramic membrane reactors]. Second final quarterly report, July--September 1993

    SciTech Connect

    Not Available

    1993-12-31

    In this quarter, the gas chromatography GC calibrations of compound No. 9, No. 11 and toluene were established. The results were accurate and reproducible using wide bore capillary column. A three-component mixture -- toluene, tetraline and compound No. 9 --also could be analyzed with a modified injection procedure. The experimental procedures of modified membrane separation were finalized based on the literature review. The coal-liquid separation could be described as an ultrafiltration process. For microporous membrane separation, two transport phenomenons, molecular diffusion and convection, were the most important mechanisms. The hindrance factors of those mechanisms were necessary to evaluate the separation performance of the membrane and to design the catalytic membrane reactor. Experimentally, with the relation of rejection and permeate flux, the hindrance factors can be calculated based on the simplified Niemi-Palosaari method. In this quarter, we first tested the 40{Angstrom} pore membrane. The preliminary results indicated that the concentration polarization was observed due to the low Reynolds number, i.e. low feed flow rate. The experimental instrumentation and procedures will be improved in the future. These factors will be used to conduct the modification of the membrane and the catalytic membrane reactor. The model compound for catalytic membrane was compound No. 9, 1-[4-[2(Phenylethyl) benzyl

  1. A hybrid process combining homogeneous catalytic ozonation and membrane distillation for wastewater treatment.

    PubMed

    Zhang, Yong; Zhao, Peng; Li, Jie; Hou, Deyin; Wang, Jun; Liu, Huijuan

    2016-10-01

    A novel catalytic ozonation membrane reactor (COMR) coupling homogeneous catalytic ozonation and direct contact membrane distillation (DCMD) was developed for refractory saline organic pollutant treatment from wastewater. An ozonation process took place in the reactor to degrade organic pollutants, whilst the DCMD process was used to recover ionic catalysts and produce clean water. It was found that 98.6% total organic carbon (TOC) and almost 100% salt were removed and almost 100% metal ion catalyst was recovered. TOC in the permeate water was less than 16 mg/L after 5 h operation, which was considered satisfactory as the TOC in the potassium hydrogen phthalate (KHP) feed water was as high as 1000 mg/L. Meanwhile, the membrane distillation flux in the COMR process was 49.8% higher than that in DCMD process alone after 60 h operation. Further, scanning electron microscope images showed less amount and smaller size of contaminants on the membrane surface, which indicated the mitigation of membrane fouling. The tensile strength and FT-IR spectra tests did not reveal obvious changes for the polyvinylidene fluoride membrane after 60 h operation, which indicated the good durability. This novel COMR hybrid process exhibited promising application prospects for saline organic wastewater treatment. PMID:27372262

  2. [Nitric Oxide Removal with a Fe-TiO₂/PSF Hybrid Catalytic Membrane Bioreactor].

    PubMed

    Li, Bao-ren; Chen, Zhou-yang; Wang, Jian-bin; Zhang, Zai-li; Fan, Qing-juan; Wei, Zai-shan

    2016-03-15

    The Fe-doped titanium dioxide (Fe-TiO₂) was prepared by the sol-gel method and was loaded on polysulfone (PSF) hollow fiber membrane. A novel Fe-TiO₂/PSF hybrid catalytic membrane biofilm reactor (HCMBfR) was investigated for nitric oxide removal, to further improve the elimination capacity. HCMBfR exhibited a good stability in the 180-day operation period, the NO removal efficiency was up to 93.2% and the maximum elimination capacity reached 167.1 g · (m³ · h)⁻1. The additional use of the biofilm to wet Fe-TiO₂/PSF membrane catalysis reactor led to the enhancement of NO removal efficiency from 59. 5% to 66% . The NO removal efficiency in the intimate coupling of Fe-TiO₂/PSF hybrid catalytic membrane and biofilm reactor ( HCMBfR) increased from 1.4% to 13% as compared to that of the membrane biofilm reactor (MBfR) only. The optimal illumination intensity, gas residence time, pH and nC/nN were 670 lx, 9 a, 6.8-7.2 and 3.7, respectively. PMID:27337874

  3. Hollow microgel based ultrathin thermoresponsive membranes for separation, synthesis, and catalytic applications.

    PubMed

    Tripathi, Bijay Prakash; Dubey, Nidhi Chandrama; Stamm, Manfred

    2014-10-22

    Thermoresponsive core-shell microgels with degradable core are synthesized via surfactant based free radical polymerization using N,N'-(1,2-dihydroxy-ethylene)bis(acrylamide) (DHEA) as a cross-linker for core preparation. The 1,2-glycol bond present in DHEA is susceptible to NaIO4 solution, and thus, the structure can be cleaved off resulting in hollow microgel. Ultrathin membranes are prepared by suction filtration of a dilute suspension of core-shell microgels over a sacrificial layer of Cd(OH)2 nanostrand coated on track etched membrane. After removal of the degraded cores from microgels, the membranes are cross-linked with glutaraldehyde and the nanostrands are removed by passing a 10 mM HCl solution. The prepared membranes are thoroughly characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and dynamic contact angle for morphology, thermoresponsive, and hydrophilic properties, respectively. The prepared membranes showed thermoresponsive permeation behavior and remarkable separation performance for low molecular weight dyes and lysozyme protein. These membranes are also used to synthesize gold nanoparticles and immobilize lactate dehydrogenase enzyme for catalytic and biocatalytic application. The results for water permeation, solute rejection, and ability to immobilize gold nanoparticles and enzymes showed its wide range of applicability. Furthermore, the synthesis of hollow microgel is simple and environmentally friendly, and the membrane preparation is easy, scalable, and other microgel systems can also be used. These responsive membranes constitute a significant contribution to advanced separation technology. PMID:25272373

  4. Ag Nanoparticle/Polydopamine-Coated Inverse Opals as Highly Efficient Catalytic Membranes.

    PubMed

    Choi, Gwan H; Rhee, Do Kyung; Park, A Reum; Oh, Min Jun; Hong, Sunghwan; Richardson, Joseph J; Guo, Junling; Caruso, Frank; Yoo, Pil J

    2016-02-10

    Polymeric three-dimensional inverse-opal (IO) structures provide unique structural properties useful for various applications ranging from optics to separation technologies. Despite vast needs for IO functionalization to impart additional chemical properties, this task has been seriously challenged by the intrinsic limitation of polymeric porous materials that do not allow for the easy penetration of waterborne moieties or precursors. To overcome this restriction, we present a robust and straightforward method of employing a dipping-based surface modification with polydopamine (PDA) inside the IO structures, and demonstrate their application to catalytic membranes via synthetic incorporation of Ag nanoparticles. The PDA coating offers simultaneous advantages of achieving the improved hydrophilicity required for the facilitated infiltration of aqueous precursors and successful creation of nucleation sites for a reduction of growth of the Ag nanoparticles. The resulting Ag nanoparticle-incorporated IO structures are utilized as catalytic membranes for the reduction of 4-nitrophenol to its amino derivatives in the presence of NaBH4. Synergistically combined characteristics of high reactivity of Ag nanoparticles along with a greatly enhanced internal surface area of IO structures enable the implementation of remarkably improved catalytic performance, exhibiting a good conversion efficiency greater than 99% while minimizing loss in the membrane permeability. PMID:26780371

  5. Feedwater cleanup for combined electrolysis catalytic exchange. Final report

    SciTech Connect

    Lentz, J.E.; Sienkiewicz, C.J.; Ellis, R.E.

    1982-07-30

    Chemical analyses were performed on a series of samples of tritiated wastewater from the Mound Effluent Recovery System (ERS). These analyses indicated that a wide range of organic impurities, as well as several specific inorganic impurities, was present in the water. One of the more damaging organic contaminants found was oil; therefore laboratory experiments were conducted to develop an oil removal method. Based on results of these analyses and experiments, a pilot scale system was designed and built to remove impurities from Mound ERS water. This system successfully removed impurities from ERS water making it suitable as feed for the combined Electrolysis Catalytic Exchange (CECE) system.

  6. Final Report, "Molecular Design of Hydrocarbon Oxidation Catalytic Processes"

    SciTech Connect

    Professor Francisco Zaera

    2007-08-09

    production of small amounts of ethylene and water, most likely via the concerted decomposition or disproportionation of the adsorbed molecular species. The bulk of the 2-iodoethanol decomposes at about 150 K via an initial carbon-iodine scission to form –O(H)CH2CH2– (~80%) and 2-hydroxyethyl (~20%) intermediates. Two competing reactions are involved with the subsequent conversion of the 2-hydroxyethyl species around 160 K, a reductive elimination with surface hydrogen to yield ethanol, and a β-H elimination to surface vinyl alcohol. The –O(H)CH2CH2–, on the other hand, dehydrogenates to a –OCH2CH2– oxametallacycle species about the same temperature. Both 2-hydroxyethyl and oxametallacycle species tautomerize to acetaldehyde, around 210 K and above 250 K, respectively, and some of that acetaldehyde desorbs while the rest decomposes to hydrogen and carbon monoxide. We contend that a better understanding of the surface chemistry of oxygen-containing surfaces can lead to better selectivities in catalysis. This is arguably the most important issue in the field of catalysis in the near future, and one that impacts several technologies of interest to DOE such as the manufacturing of speciality chemicals and the control and removal of pollutants. Additional work was performed on the characterization of the chemistry of methyl and methylene adsorbed species on oxygen-treated nickel surfaces. Complex chemistry was observed involving not only hydrogenation and dehydrogenation steps, but also C-C couplings and methylene insertions to produce heavier hydrocarbons, and oxygen insertion reactions that yield oxygenates. Finally, a dual titration technique employing xenon and a chemically sensitive probe was developed to identify minority catalytic sites on oxide surfaces. In the case of oxygen-treated Ni(110) single crystals, it was found that both hydrogen transfer with adsorbed water or ammonia and certain hydrocarbon hydrogenation reactions take place at the end of the

  7. Development of combined electrolysis catalytic exchange. Final report

    SciTech Connect

    Ellis, R.E.; Lentz, J.E.; Rogers, M.L.; Sienkiewicz, C.J.

    1982-06-24

    Aqueous wastes contaminated with tritium in the form of HTO pose a difficult disposal problem. Since the only difference between HTO and the major constituent (H/sub 2/O) of such wastes is the isotopic form of the hydrogen, an isotopic separation process is required for decontamination of these wastes. Several processes were tried experimentally before the Combined Electrolysis Catalytic Exchange (CECE) process was chosen for pilot-scale development. This process concentrates tritium in the water phase by contacting gaseous hydrogen with water over a catalyst. Experimental work was performed to determine the effects of tritium radiolysis on the electrolysis cells and exchange catalyst. Processes to remove impurities from the feed stream were developed, and in order to evaluate feasibility, a small, pilot-scale CECE system was designed, built, and operated. Several potential applications are discussed, and results of experimenta work for two of these applications are given.

  8. Supported liquid membrane battery separators. Final report

    SciTech Connect

    Pemsler, J.P.; Dempsey, M.D.

    1984-07-01

    This study was performed to explore the feasibility of using a supported liquid membrane (SLM) as a separator in the nickel-zinc battery. In particular, SLM separators should prevent zinc dendrite growth from shorting out the cell and might also alleviate capacity loss due to zinc electrode shape changes. A number of ion exchange/solvent modifier systems for incorporation into SLMs were developed under a previous LBL contract. SLMs prepared with these reagents exhibited resistances in the range of 0.4 to 10 ohm cm/sup 2/, selectively transported hydroxyl ions over zincate ions by a factor of 10/sup 6/ to 10/sup 7/, and possessed eletrochemical and chemical stability in alkaline electrolytes. In order to evaluate these SLM separators under conditions closely resembling a commercial Ni-Zn cell, an accelerated cycle life test was devised using commercial electrodes.

  9. Conversion of elemental mercury with a novel membrane delivery catalytic oxidation system (MDCOs).

    PubMed

    Guo, Yongfu; Yan, Naiqiang; Yang, Shijian; Qu, Zan; Wu, Zhongbiao; Liu, Yue; Liu, Ping; Jia, Jinping

    2011-01-15

    In order to overcome the shortcomings of the traditional catalytic oxidation (TCO) mode for the conversion of the trace level of elemental mercury (Hg(0)) in flue gas, we put forward a novel and unique assembly that integrated membrane delivery with catalytic oxidation systems (MDCOs), which combined the controlled delivery of oxidants with the catalytic oxidation of Hg(0). The results show that the demanded HCl for Hg(0) conversion in the MDCOs was less than 5% of that in the TCO mode, and over 90% of Hg(0) removal efficiency can be obtained in the MDCOs with less than 0.5 mg m(-3) of HCl escaped. Meanwhile, the inhibition of SO(2) to Hg(0) catalytic conversion in the MDCOs was also less significant than in the TCO. The MDCOs have high retainability for HCl, which is quite favorable to Hg(0) conversion and HCl utilization. The reaction mechanism on mercury conversion in the MDCOs is discussed. The MDCOs appear to be a promising method for emission control of elemental mercury. PMID:21158439

  10. Final Technical Report [Development of Catalytic Alkylation and Fluoroalkylation Methods

    SciTech Connect

    Vicic, David A.

    2014-05-01

    In the early stages of this DOE-funded research project, we sought to prepare and study a well-defined nickel-alkyl complex containing tridentate nitrogen donor ligands. We found that reaction of (TMEDA)NiMe2 (1) with terpyridine ligand cleanly led to the formation of (terpyridyl)NiMe (2), which we also determined to be an active alkylation catalyst. The thermal stability of 2 was unlike that seen for any of the active pybox ligands, and enabled a number of key studies on alkyl transfer reactions to be performed, providing new insights into the mechanism of nickel-mediated alkyl-alkyl cross-coupling reactions. In addition to the mechanistic studies, we showed that the terpyridyl nickel compounds can catalytically cross-couple alkyl iodides in yields up to 98% and bromides in yields up to 46 %. The yields for the bromides can be increased up to 67 % when the new palladium catalyst [(tpy’)Pd-Ph]I is used. The best route to the targeted [(tpy)NiBr] (1) was found to involve the comproportionation reaction of [(dme)NiBr{sub 2}] and [Ni(COD){sub 2}] in the presence of two equivalents of terpyridine. This reaction was driven to high yields of product formation (72 % isolated) by the precipitation of 1 from THF solvent.

  11. Non-catalytic steam hydrolysis of fats. Final report

    SciTech Connect

    Deibert, M.C.

    1992-08-28

    Hydrolysis of fats and oils produces fatty acid and glycerol. The catalyzed, liquid phase Colgate-Emry process, state-of-the-art, produces impure products that require extensive energy investment for their purification to commercial grade. Non-catalytic steam hydrolysis may produce products more easily purified. A bench-scale hydrolyzer was designed and constructed to contact descending liquid fat or oil with rising superheated steam. Each of the five stages in the reactor was designed similar to a distillation column stage to promote intimate liquid-gas contact. Degree of hydrolysis achieved in continuous tests using tallow feed were 15% at 280C and 35% at 300C at a tallow-to-steam mass feed ratio of 4.2. At a feed ratio of 9.2, the degree of hydrolysis was 21% at 300C. Decomposition was strongly evident at 325C but not at lower temperatures. Soybean oil rapidly polymerized under reaction conditions. Batch tests at 320C produced degrees of hydrolyses of between 44% and 63% using tallow and palm oil feeds. Over 95% fatty acids were present in a clean, readily separated organic portion of the overhead product from most tests. The test reactor had serious hydraulic resistance to liquid down-flow which limited operation to very long liquid residence times. These times are in excess of those that tallow and palm oil are stable at the reaction temperature. Little glycerol and extensive light organics were produced indicating that unexplained competing reactions to hydrolysis occurred in the experimental system. Further tests using an improved reactor will be required.

  12. Instantaneous Click Chemistry by a Copper-Containing Polymeric-Membrane-Installed Microflow Catalytic Reactor.

    PubMed

    Yamada, Yoichi M A; Ohno, Aya; Sato, Takuma; Uozumi, Yasuhiro

    2015-11-23

    The copper(I)-catalyzed Huisgen cycloaddition (azide-alkyne cycloaddition) is an important reaction in click chemistry that ideally proceeds instantaneously. An instantaneous Huisgen cycloaddition has been developed that uses a novel catalytic dinuclear copper complex-containing polymeric membrane-installed microflow device. A polymeric membranous copper catalyst was prepared from poly(4-vinylpyridine), copper(II) sulfate, sodium chloride, and sodium ascorbate at the interface of two laminar flows inside microchannels. Elucidation of the structure by XANES, EXAFS, and elemental analysis, as well as second-order Møller-Plesset perturbation theory (MP2) calculations and density functional theory (DFT) calculations assigned the local structure near Cu as a μ-chloro dinuclear Cu(I) complex. The microflow device promotes the instantaneous click reaction of a variety of alkynes and organic azides to afford the corresponding triazoles in quantitative yield. PMID:26439220

  13. Simple fabrication of a Pd-P film on a polymer membrane and its catalytic applications.

    PubMed

    Byeon, Jeong Hoon; Kim, Young-Woo

    2011-08-01

    Composites were prepared by a surface activation by aerosol deposition of Pd nanoparticles (Pd nano seeds) on a poly(tetrafluoroethylene) membrane and subsequent Pd-P film formation by electroless deposition. Activation of the membrane processed by an ambient Pd spark discharge and subsequent fixation of the spark produced Pd nano seeds. Characterizations for electroless Pd-P films indicated that P entered into the crystal lattice of Pd and formed an alloy. The fabricated composites were applied to catalytic applications of formic acid oxidation (FAO) and toluene conversion (TC). The composite catalysts from the simple activation had more stable performances of FAO and TC than those from the conventional Sn-Pd activation, and their better performances might have originated from better purity due to the simple activation that only introduced pure Pd nano seeds. PMID:21736292

  14. PKC-ε pseudosubstrate and catalytic activity are necessary for membrane delivery during IgG-mediated phagocytosis

    PubMed Central

    Wood, Tiffany R.; Chow, Rachel Y.; Hanes, Cheryl M.; Zhang, Xuexin; Kashiwagi, Kaori; Shirai, Yasuhito; Trebak, Mohamed; Loegering, Daniel J.; Saito, Naoaki; Lennartz, Michelle R.

    2013-01-01

    In RAW 264.7 cells [1], PKC-ε regulates FcγR-mediated phagocytosis. BMDM behave similarly; PKC-ε concentrates at phagosomes and internalization are reduced in PKC-ε−/− cells. Two questions were asked: what is the role of PKC-ε? and what domains are necessary for PKC-ε concentration? Function was studied using BMDM and frustrated phagocytosis. On IgG surfaces, PKC-ε−/− macrophages spread less than WT. Patch-clamping revealed that the spreading defect is a result of the failure of PKC-ε−/− macrophages to add membrane. The defect is specific for FcγR ligation and can be reversed by expression of full-length (but not the isolated RD) PKC-ε in PKC-ε−/− BMDM. Thus, PKC-ε function in phagocytosis requires translocation to phagosomes and the catalytic domain. The expression of chimeric PKC molecules in RAW cells identified the εPS as necessary for PKC-ε targeting. When placed into (nonlocalizing) PKC-δ, εPS was sufficient for concentration, albeit to a lesser degree than intact PKC-ε. In contrast, translocation of δ(εPSC1B) resembled that of WT PKC-ε. Thus, εPS and εC1B cooperate for optimal phagosome targeting. Finally, cells expressing εK437W were significantly less phagocytic than their PKC-ε-expressing counterparts, blocked at the pseudopod-extension phase. In summary, we have shown that εPS and εC1B are necessary and sufficient for targeting PKC-ε to phagosomes, where its catalytic activity is required for membrane delivery and pseudopod extension. PMID:23670290

  15. Comparative catalytic activity of PET track-etched membranes with embedded silver and gold nanotubes

    NASA Astrophysics Data System (ADS)

    Mashentseva, Anastassiya; Borgekov, Daryn; Kislitsin, Sergey; Zdorovets, Maxim; Migunova, Anastassiya

    2015-12-01

    Irradiated by heavy ions nanoporous polyethylene terephthalate track-etched membranes (PET TeMs) after +15Kr84 ions bombardment (1.75 MeV/nucl with the ion fluency of 1 × 109 cm-2) and sequential etching was applied in this research as a template for development of composites with catalytically enriched properties. A highly ordered silver and gold nanotubes arrays were embedded in 100 nm pores of PET TeMs via electroless deposition technique at 4 °C during 1 h. All "as-prepared" composites were examined for catalytic activity using reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride as a common reaction to test metallic nanostructures catalysts. The effect of temperature on the catalytic activity was investigated in range of 292-313 K and activation energy were calculated. Kapp of Ag/PET composites linearly increase with an increase of the temperature thus normal Arrhenius behavior have been seen and the activation energy was calculated to be 42.13 kJ/mol. Au/PET composites exhibit not only more powerful catalytic activity but also non-linear dependence of rate constant from temperature. Kapp increased with increasing temperature throughout the 292-308 K temperature range; the reaction had an activation energy 65.32 kJ/mol. In range 311-313 K rate constant dramatically decreased and the apparent activation energy at this temperature rang was -91.44 kJ/mol due some structural changes, i.e. agglomeration of Au nanoparticles on the surface of composite.

  16. Green Fabrication of Ag Coated Polyacrylonitrile Nanofibrous Composite Membrane with High Catalytic Efficiency.

    PubMed

    Shen, Lingdi; Yu, Lina; Wang, Min; Wang, Xuefen; Zhu, Meifang; Hsiao, Benjamin S

    2015-07-01

    Ag-coated polyacrylonitrile (PAN) nanofibers have been prepared by a novel, facile and green way that combined electrospinning technique and poly(dopamine)-assisted electroless plating method. Poly(dopamine) (PDOP) was formed by oxidation polymerization of dopamine on the surface of PAN nanofibers to promote the electroless plating of silver. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and energy dispersive X-ray spectroscopy (EDS) were used to characterize the morphology and structure of Ag/PDOP/PAN nanofibrous composite mem- brane and Ultraviolet-visible (UV-vis) Spectroscopy was used to investigate its catalytic performance. The results indicated that silver clusters composed of face-centred cubic crystal Ag with average crystallite size of about 18 nm were well distributed on the surface of dopamine-modified electrospun PAN nanofibers (PDOP/PAN). The prepared silver coated PDOP/PAN (Ag/PDOP/PAN) nanofibrous composite membrane exhibited an outstanding catalytic performance, and showed good reusabil- ity for completely degradating methylene blue (MB) dyes and reducing o-nitroaniline very quickly, respectively. PMID:26373068

  17. Architecture of a single membrane spanning cytochrome P450 suggests constraints that orient the catalytic domain relative to a bilayer

    PubMed Central

    Monk, Brian C.; Tomasiak, Thomas M.; Keniya, Mikhail V.; Huschmann, Franziska U.; Tyndall, Joel D. A.; O’Connell, Joseph D.; Cannon, Richard D.; McDonald, Jeffrey G.; Rodriguez, Andrew; Finer-Moore, Janet S.; Stroud, Robert M.

    2014-01-01

    Bitopic integral membrane proteins with a single transmembrane helix play diverse roles in catalysis, cell signaling, and morphogenesis. Complete monospanning protein structures are needed to show how interaction between the transmembrane helix and catalytic domain might influence association with the membrane and function. We report crystal structures of full-length Saccharomyces cerevisiae lanosterol 14α-demethylase, a membrane monospanning cytochrome P450 of the CYP51 family that catalyzes the first postcyclization step in ergosterol biosynthesis and is inhibited by triazole drugs. The structures reveal a well-ordered N-terminal amphipathic helix preceding a putative transmembrane helix that would constrain the catalytic domain orientation to lie partly in the lipid bilayer. The structures locate the substrate lanosterol, identify putative substrate and product channels, and reveal constrained interactions with triazole antifungal drugs that are important for drug design and understanding drug resistance. PMID:24613931

  18. Architecture of a single membrane spanning cytochrome P450 suggests constraints that orient the catalytic domain relative to a bilayer.

    PubMed

    Monk, Brian C; Tomasiak, Thomas M; Keniya, Mikhail V; Huschmann, Franziska U; Tyndall, Joel D A; O'Connell, Joseph D; Cannon, Richard D; McDonald, Jeffrey G; Rodriguez, Andrew; Finer-Moore, Janet S; Stroud, Robert M

    2014-03-11

    Bitopic integral membrane proteins with a single transmembrane helix play diverse roles in catalysis, cell signaling, and morphogenesis. Complete monospanning protein structures are needed to show how interaction between the transmembrane helix and catalytic domain might influence association with the membrane and function. We report crystal structures of full-length Saccharomyces cerevisiae lanosterol 14α-demethylase, a membrane monospanning cytochrome P450 of the CYP51 family that catalyzes the first postcyclization step in ergosterol biosynthesis and is inhibited by triazole drugs. The structures reveal a well-ordered N-terminal amphipathic helix preceding a putative transmembrane helix that would constrain the catalytic domain orientation to lie partly in the lipid bilayer. The structures locate the substrate lanosterol, identify putative substrate and product channels, and reveal constrained interactions with triazole antifungal drugs that are important for drug design and understanding drug resistance. PMID:24613931

  19. MAP-1 and IAP-1, two novel AAA proteases with catalytic sites on opposite membrane surfaces in mitochondrial inner membrane of Neurospora crassa.

    PubMed

    Klanner, C; Prokisch, H; Langer, T

    2001-09-01

    Eukaryotic AAA proteases form a conserved family of membrane-embedded ATP-dependent proteases but have been analyzed functionally only in the yeast Saccharomyces cerevisiae. Here, we have identified two novel members of this protein family in the filamentous fungus Neurospora crassa, which were termed MAP-1 and IAP-1. Both proteins are localized to the inner membrane of mitochondria. They are part of two similar-sized high molecular mass complexes, but expose their catalytic sites to opposite membrane surfaces, namely, the intermembrane and the matrix space. Disruption of iap-1 by repeat-induced point mutation caused a slow growth phenotype at high temperature and stabilization of a misfolded inner membrane protein against degradation. IAP-1 could partially substitute for functions of its yeast homolog Yme1, demonstrating functional conservation. However, respiratory growth at 37 degrees C was not restored. Our results identify two components of the quality control system of the mitochondrial inner membrane in N. crassa and suggest that AAA proteases with catalytic sites exposed to opposite membrane surfaces are present in mitochondria of all eukaryotic cells. PMID:11553723

  20. Gas separations using ceramic membranes. Final report, September 1988--February 1993

    SciTech Connect

    Lin, C.L.; Wu, J.C.S.; Gallaher, G.R.; Smith, G.W.; Flowers, D.L.; Gerdes, T.E.; Liu, P.K.T.

    1993-02-01

    This study covers a comprehensive evaluation of existing ceramic membranes for high temperature gas separations. Methodology has been established for microporous characterization stability and gas separation efficiency. A mathematical model was developed to predict gas separations with existing membranes. Silica and zeolitic modifications of existing membranes were pursued to enhance its separation efficiency. Some of which demonstrate unique separations properties. Use of the dense-silica membranes for hydrogen enrichment was identified as a promising candidate for future development. In addition, the decomposition of trace ammonia contaminant via a catalytic membrane reactor appears feasible. A further economic analysis is required to assess its commercial viability.

  1. Phosphatidylserine-containing membranes alter the thermal stability of prothrombin's catalytic domain: a differential scanning calorimetric study.

    PubMed

    Lentz, B R; Zhou, C M; Wu, J R

    1994-05-10

    Denaturation profiles of bovine prothrombin and its isolated fragments were examined in the presence of Na2EDTA, 5 mM CaCl2, and CaCl2 plus membranes containing 1-palmitoyl-2-oleoyl-3-sn-phosphatidylcholine (POPC) in combination with bovine brain phosphatidylserine (PS). We have shown previously [Lentz, B. R., Wu, J. R., Sorrentino, A. M., & Carleton, J. A. (1991) Biophys. J. 60, 70] that binding to PS/POPC (25/75) large unilamellar vesicles resulted in an enthalpy loss in the main endotherm of prothrombin denaturation (Tm approximately 57-58 degrees C) and a comparable enthalpy gain in a minor endotherm (Tm approximately 59 degrees C) accompanying an upward shift in peak temperature (Tm approximately 73 degrees C). This minor endotherm was also responsive to Ca2+ binding and, in the absence of PS/POPC membranes, corresponded to melting of the N-terminal, Ca2+ and membrane binding domain (fragment 1). Peak deconvolution analysis of the prothrombin denaturation profile and extensive studies of the denaturation of isolated prothrombin domains in the presence and absence of PS/POPC vesicles suggested that membrane binding induced changes in the C-terminal catalytic domain of prothrombin (prethrombin 2) and in a domain that links fragment 1 with the catalytic domain (fragment 2). Specifically, the results have confirmed that the fragment 2 domain interacts with the stabilizes the prethrombin 2 domain and also have shown that fragment 2 interacts directly with the membrane. In addition, the results have demonstrated a heretofore unrecognized interaction between the catalytic and membrane binding domains. This interaction can account for another portion of the denaturation enthalpy that appears at high temperatures in the presence of membranes.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8180168

  2. Development of catalytically active and highly stable catalyst supports for polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kim, Taekeun; Xie, Tianyuan; Jung, Wonsuk; Gadala-Maria, Francis; Ganesan, Prabhu; Popov, Branko N.

    2015-01-01

    Novel procedures are developed for the synthesis of highly stable carbon composite catalyst supports (CCCS-800 °C and CCCS-1100 °C) and an activated carbon composite catalyst support (A-CCCS). These supports are synthesized through: (i) surface modification with acids and inclusion of oxygen groups, (ii) metal-catalyzed pyrolysis, and (iii) chemical leaching to remove excess metal used to dope the support. The procedure results in increasing carbon graphitization and inclusion of non-metallic active sites on the support surface. Catalytic activity of CCCS indicates an onset potential of 0.86 V for the oxygen reduction reaction (ORR) with well-defined kinetic and mass-transfer regions and ∼2.5% H2O2 production in rotating ring disk electrode (RRDE) studies. Support stability studies at 1.2 V constant potential holding for 400 h indicate high stability for the 30% Pt/A-CCCS catalyst with a cell potential loss of 27 mV at 800 mA cm-2 under H2-air, 32% mass activity loss, and 30% ECSA loss. Performance evaluation in polymer electrolyte membrane (PEM) fuel cell shows power densities (rated) of 0.18 and 0.23 gPt kW-1 for the 30% Pt/A-CCCS and 30% Pt/CCCS-800 °C catalysts, respectively. The stabilities of various supports developed in this study are compared with those of a commercial Pt/C catalyst.

  3. Microwave assisted esterification of acidified oil from waste cooking oil by CERP/PES catalytic membrane for biodiesel production.

    PubMed

    Zhang, Honglei; Ding, Jincheng; Zhao, Zengdian

    2012-11-01

    The traditional heating and microwave assisted method for biodiesel production using cation ion-exchange resin particles (CERP)/PES catalytic membrane were comparatively studied to achieve economic and effective method for utilization of free fatty acids (FFAs) from waste cooking oil (WCO). The optimal esterification conditions of the two methods were investigated and the experimental results showed that microwave irradiation exhibited a remarkable enhanced effect for esterification compared with that of traditional heating method. The FFAs conversion of microwave assisted esterification reached 97.4% under the optimal conditions of reaction temperature 60°C, methanol/acidified oil mass ratio 2.0:1, catalytic membrane (annealed at 120°C) loading 3g, microwave power 360W and reaction time 90min. The study results showed that it is a fast, easy and green way to produce biodiesel applying microwave irradiation. PMID:22940301

  4. The development of manganese oxide coated ceramic membranes for combined catalytic ozonation and ultrafiltration of drinking water

    NASA Astrophysics Data System (ADS)

    Corneal, Lindsay Marie

    A novel method for the preparation of hydrated MnO2 by the ozonation of MnCl2 in water is described. The hydrated MnO 2 was used to coat titania water filtration membranes using a layer-by-layer technique. The coated membranes were then sintered in air at 500°C for 45 minutes. Upon sintering, the MnO2 is converted to alpha-Mn 2O3 (as characterized by x-ray and electron diffraction). Atomic force microscopy (AFM) imaging showed no significant change in the roughness or height of the surface features of coated membranes, while scanning electron microscopy (SEM) imaging showed an increase in grain size with increasing number of coating layers. Energy dispersive x-ray spectroscopy (EDS) mapping and line scans revealed manganese present throughout the membrane, indicating that manganese dispersed into the porous membrane during the coating process and diffused into the titania grains during sintering. Selected area diffraction (SAD) of the coated and sintered membrane was used to index the surface layer as alpha-Mn2O3. The surface layer was uneven, although there was a trend of increasing thickness with increasing coating layers. The coating acts as a catalyst for the oxidation of organic matter when coated membranes are used in a hybrid ozonation-membrane filtration system. A trend of decreasing total organic carbon (TOC) in the permeate water was observed with increasing number of coating layers. The catalytic activity also manifests itself as improved recovery of the water flux due to oxidation of foulants on the membrane surface. Ceramic nanoparticle coatings on ceramic water filtration membranes must undergo high temperature sintering. However, this means that the underlying membrane, which has been engineered for a given molecular weight cut-off (MWCO), also undergoes a high temperature heat treatment that serves to increase pore size that have resulted in increases in permeability of titania membranes. Coating the titania membrane with manganese oxide followed

  5. Development of ceramic membrane reactors for high temperature gas cleanup. Final report

    SciTech Connect

    Roberts, D.L.; Abraham, I.C.; Blum, Y.; Gottschlich, D.E.; Hirschon, A.; Way, J.D.; Collins, J.

    1993-06-01

    The objective of this project was to develop high temperature, high pressure catalytic ceramic membrane reactors and to demonstrate the feasibility of using these membrane reactors to control gaseous contaminants (hydrogen sulfide and ammonia) in integrated gasification combined cycle (IGCC) systems. Our strategy was to first develop catalysts and membranes suitable for the IGCC application and then combine these two components as a complete membrane reactor system. We also developed a computer model of the membrane reactor and used it, along with experimental data, to perform an economic analysis of the IGCC application. Our results have demonstrated the concept of using a membrane reactor to remove trace contaminants from an IGCC process. Experiments showed that NH{sub 3} decomposition efficiencies of 95% can be achieved. Our economic evaluation predicts ammonia decomposition costs of less than 1% of the total cost of electricity; improved membranes would give even higher conversions and lower costs.

  6. Catalytic conversion of light alkanes. Final report, January 1, 1990--October 31, 1994

    SciTech Connect

    1998-12-31

    During the course of the first three years of the Cooperative Agreement (Phase I-III), we uncovered a family of metal perhaloporphyrin complexes which had unprecedented activity for the selective air-oxidation of fight alkanes to alcohols. The reactivity of fight hydrocarbon substrates with air or oxygen was in the order: isobutane>propane>ethane>methane, in accord with their homolytic bond dissociation energies. Isobutane was so reactive that the proof-of concept stage of a process for producing tert-butyl alcohol from isobutane was begun (Phase V). It was proposed that as more active catalytic systems were developed (Phases IV, VI), propane, then ethane and finally methane oxidations will move into this stage (Phases VII through IX). As of this writing, however, the program has been terminated during the later stages of Phases V and VI so that further work is not anticipated. We made excellent progress during 1994 in generating a class of less costly new materials which have the potential for high catalytic activity. New routes were developed for replacing costly perfluorophenyl groups in the meso-position of metalloporphyrin catalysts with far less expensive and lower molecular weight perfluoromethyl groups.

  7. Research and development to overcome fouling of membranes. Final report

    SciTech Connect

    Narang, S.C.; Sharma, S.K.; Hum, G.; Ventura, S.C.; Roberts, D.L.; Gottschlich, D.; Ahner, N.

    1998-11-01

    To overcome fouling of membranes, SRI International is developing a unique piezoelectric backing for ultrafiltration membranes. This backing is capable of producing local turbulence next to the membrane to minimize concentration polarization and the rate of buildup of solutes and particulate matter on the membrane surface. We have studied piezoelectrically assisted ultrafiltration in more detail, with the objective to apply this process to industrial ultrafiltrations. We conducted several ultrafiltration experiments on flat sheet membranes with model dextran solutions and with electrocoat paint to study flux enhancement as a function of parameters such as feed flow rate, feed pressure, as well as the piezodriver-membrane system.

  8. A Novel Family of Soluble Minimal Scaffolds Provides Structural Insight into the Catalytic Domains of Integral Membrane Metallopeptidases*

    PubMed Central

    López-Pelegrín, Mar; Cerdà-Costa, Núria; Martínez-Jiménez, Francisco; Cintas-Pedrola, Anna; Canals, Albert; Peinado, Juan R.; Marti-Renom, Marc A.; López-Otín, Carlos; Arolas, Joan L.; Gomis-Rüth, F. Xavier

    2013-01-01

    In the search for structural models of integral-membrane metallopeptidases (MPs), we discovered three related proteins from thermophilic prokaryotes, which we grouped into a novel family called “minigluzincins.” We determined the crystal structures of the zymogens of two of these (Pyrococcus abyssi proabylysin and Methanocaldococcus jannaschii projannalysin), which are soluble and, with ∼100 residues, constitute the shortest structurally characterized MPs to date. Despite relevant sequence and structural similarity, the structures revealed two unique mechanisms of latency maintenance through the C-terminal segments previously unseen in MPs as follows: intramolecular, through an extended tail, in proabylysin, and crosswise intermolecular, through a helix swap, in projannalysin. In addition, structural and sequence comparisons revealed large similarity with MPs of the gluzincin tribe such as thermolysin, leukotriene A4 hydrolase relatives, and cowrins. Noteworthy, gluzincins mostly contain a glutamate as third characteristic zinc ligand, whereas minigluzincins have a histidine. Sequence and structural similarity further allowed us to ascertain that minigluzincins are very similar to the catalytic domains of integral membrane MPs of the MEROPS database families M48 and M56, such as FACE1, HtpX, Oma1, and BlaR1/MecR1, which are provided with trans-membrane helices flanking or inserted into a minigluzincin-like catalytic domain. In a time where structural biochemistry of integral-membrane proteins in general still faces formidable challenges, the minigluzincin soluble minimal scaffold may contribute to our understanding of the working mechanisms of these membrane MPs and to the design of novel inhibitors through structure-aided rational drug design approaches. PMID:23733187

  9. Solid support membrane-aerated catalytic biofilm reactor for the continuous synthesis of (S)-styrene oxide at gram scale.

    PubMed

    Halan, Babu; Letzel, Thomas; Schmid, Andreas; Buehler, Katja

    2014-10-01

    Catalytic biofilms minimize reactant toxicity and maximize biocatalyst stability in selective transformations of chemicals to value-added products in continuous processes. The scaling up of such catalytic biofilm processes is challenging, due to fluidic and biological parameters affording a special reactor design affecting process performance. A solid support membrane-aerated biofilm reactor was optimized and scaled-up to yield gram amounts of (S)-styrene oxide, a toxic and instable high value chemical synthon. A sintered stainless steel membrane unit was identified as an optimal choice as biofilm substratum and for high oxygen mass transfer. A stable expanded polytetrafluoroethylene (ePTFE) membrane was best suited for in situ substrate delivery and product extraction. For the verification of scalability, catalytic biofilms of Pseudomonas sp. strain VLB120ΔC produced (S)-styrene oxide to an average concentration of 390 mM in the organic phase per day (equivalent to 24.4 g Laq (-1) day(-1) ). This productivity was gained by efficiently using the catalyst with an excellent product yield on biomass of 13.6 gproduct gbiomass (-1) . This product yield on biomass is in the order of magnitude reported for other continuous systems based on artificially immobilized biocatalysts and is fulfilling the minimum requirements for industrial biocatalytic processes. Overall, 46 g of (S)-styrene oxide were produced and isolated (purity: 99%; enantiomeric excess [ee]: >99.8%. yield: 30%). The productivity is in a similar range as in comparable small-scale biofilm reactors highlighting the large potential of this methodology for continuous bioprocessing of bulk chemicals and biofuels. PMID:25111808

  10. Silica membranes for hydrogen separation from coal gas. Final report

    SciTech Connect

    Gavalas, G.R.

    1996-01-01

    This project is a continuation of a previous DOE-UCR project (DE-FG22- 89PC89765) dealing with the preparation of silica membranes highly permselective to hydrogen at elevated temperatures, suitable for hydrogen separation from coal gas. The membranes prepared in the previous project had very high selectivity but relatively low permeance. Therefore, the general objectives of this project were to improve the permeance of these membranes and to obtain fundamental information about membrane structure and properties. The specific objectives were: (1) to explore new silylation reagents and reaction conditions with the purpose of reducing the thickness and increasing the permeance of silica membranes prepared by chemical vapor deposition (CVD), (2) to characterize the membrane structure, (3) to delineate mechanism and kinetics of deposition, (4) to measure the permeability of silica layers at different extents of deposition, and (5) to mathematically model the relationship between structure and deposition kinetics.

  11. Final Report - Membranes and MEA's for Dry, Hot Operating Conditions

    SciTech Connect

    Hamrock, Steven J

    2011-06-30

    The focus of this program was to develop a new Proton Exchange Membrane (PEM) which can operate under hotter, dryer conditions than the state of the art membranes today and integrate it into a Membrane Electrode Assembly (MEA). These MEA's should meet the performance and durability requirements outlined in the solicitation, operating under low humidification conditions and at temperatures ranging from -20ºC to 120ºC, to meet 2010 DOE technical targets for membranes. This membrane should operate under low humidification conditions and at temperatures ranging from -20ºC to 120ºC in order to meet DOE HFCIT 2010 commercialization targets for automotive fuel cells. Membranes developed in this program may also have improved durability and performance characteristics making them useful in stationary fuel cell applications. The new membranes, and the MEA's comprising them, should be manufacturable at high volumes and at costs which can meet industry and DOE targets. This work included: A) Studies to better understand factors controlling proton transport within the electrolyte membrane, mechanisms of polymer degradation (in situ and ex situ) and membrane durability in an MEA; B) Development of new polymers with increased proton conductivity over the range of temperatures from -20ºC to 120ºC and at lower levels of humidification and with improved chemical and mechanical stability; C) Development of new membrane additives for increased durability and conductivity under these dry conditions; D) Integration of these new materials into membranes and membranes into MEA's, including catalyst and gas diffusion layer selection and integration; E) Verification that these materials can be made using processes which are scalable to commercial volumes using cost effective methods; F) MEA testing in single cells using realistic automotive testing protocols. This project addresses technical barriers A (Durability) and C (Performance) from the Fuel Cells section of the 2005 Hydrogen

  12. Thermal and chemical degradation of inorganic membrane materials. Final report, August 1992--May 1995

    SciTech Connect

    Damle, A.S.; Krishnan, G.N.; Sanjurjo, A.; Wood, B.J.; Lau, K.H.

    1995-05-01

    SRI International conducted a theoretical and experimental program to evaluate the long-term thermal and chemical degradation of inorganic membranes that are being developed to separate the gaseous products of coal gasification. A variety of developmental efforts are underway, including a number of projects sponsored by the US Department of Energy (DOE), to improve the selectivity and permeability of porous inorganic membranes. DOE is also sponsoring efforts to extend the use of metallic membranes to new applications. Most developmental efforts have focused on hydrogen separation by inorganic membranes, which may be used to maximize hydrogen production from coal gas or to remove H{sub 2}S and NH{sub 3} contaminants via thermal or catalytic decomposition in integrated-gasification combined-cycle (IGCC) systems. Inorganic membranes that have a high separation efficiency and exhibit both thermal and chemical stability would improve the economics of power generation from coal. Membrane materials that have been investigated include glass (silica), alumina, carbon, and metals (Pd and Pt). This report describes inorganic membrane materials, long term membrane exposure tests, membrane permeation tests, coal gasifier exposure tests, conclusions, and recommendations.

  13. Development of phosphate-based ceramic membranes. Final report

    SciTech Connect

    Anderson, M.A.; Zeltner, W.A.; Hill, C.G. Jr.

    1992-11-01

    Goal was to develop microporous ceramic membranes by coating sols that contain nanoparticles onto porous ceramic supports. They could be used for either gas phase separations or liquid phase separations involving low molecular weight solutes. This required the synthesis of Sols containing particles in the range from 2 to 10 nm. Procedures for preparing nanoparticulate sols of silica, alumina, and aluminosilicates of various compositions are given. Unsupported ceramic membranes prepared from these sols had mean pore diameters of <10 {Angstrom} (silica), ca. 35 {Angstrom} (aluminosilicate). The alumina membranes display both microporosity (mean pore diameters <20 {Angstrom}) and mesoporosity (mean pore diameters >20 {Angstrom}). These nanoparticulate sols were deposited onto porous supports. Four methods of were investigated. Dip coating appeared to give the best performance of all of these techniques and was easily implemented. Deposition of particles within porous supports by permformation was also demonstrated. Critical point drying studies of membranes were initiated, but progress was limited. Slip casting could not be successfully used to produce a supported membrane free from cracks.

  14. Advanced membrane separation technology for biosolvents. Final CRADA report.

    SciTech Connect

    Snyder, S. W.; Energy Systems

    2010-02-08

    Argonne and Vertec Biosolvents investigated the stability and perfonnance for a number of membrane systems to drive the 'direct process' for pervaporation-assisted esterification to produce lactate esters. As outlined in Figure 1, the target is to produce ammonium lactate by fennentation. After purification and concentration, ammonium lactate is reacted with ethanol to produce the ester. Esterification is a reversible reaction so to drive the reaction forward, the produced ammonia and water must be rapidly separated from the product. The project focused on selecting pervaporation membranes with (1) acid functionality to facilitate ammonia separation and (2) temperature stability to be able to perform that reaction at as high a temperature as possible (Figure 2). Several classes of commercial membrane materials and functionalized membrane materials were surveyed. The most promising materials were evaluated for scale-up to a pre-commercial application. Over 4 million metric tons per year of solvents are consumed in the U.S. for a wide variety of applications. Worldwide the usage exceeds 10 million metric tons per year. Many of these, such as the chlorinated solvents, are environmentally unfriendly; others, such as the ethylene glycol ethers and N Methyl Pyrrolidone (NMP), are toxic or teratogenic, and many other petroleum-derived solvents are coming under increasing regulatory restrictions. High performance, environmentally friendly solvents derived from renewable biological resources have the potential to replace many of the chlorinated and petrochemical derived solvents. Some of these solvents, such as ethyl lactate; d-limonene, soy methyl esters, and blends ofthese, can give excellent price/perfonnance in addition to the environmental and regulatory compliance benefits. Advancement of membrane technologies, particularly those based on pervaporation and electrodialysis, will lead to very efficient, non-waste producing, and economical manufacturing technologies for

  15. Advanced treatment of biologically pretreated coal gasification wastewater by a novel integration of catalytic ultrasound oxidation and membrane bioreactor.

    PubMed

    Jia, Shengyong; Han, Hongjun; Zhuang, Haifeng; Xu, Peng; Hou, Baolin

    2015-01-01

    Laboratorial scale experiments were conducted to investigate a novel system integrating catalytic ultrasound oxidation (CUO) with membrane bioreactor (CUO-MBR) on advanced treatment of biologically pretreated coal gasification wastewater. Results indicated that CUO with catalyst of FeOx/SBAC (sewage sludge based activated carbon (SBAC) which loaded Fe oxides) represented high efficiencies in eliminating TOC as well as improving the biodegradability. The integrated CUO-MBR system with low energy intensity and high frequency was more effective in eliminating COD, BOD5, TOC and reducing transmembrane pressure than either conventional MBR or ultrasound oxidation integrated MBR. The enhanced hydroxyl radical oxidation, facilitation of substrate diffusion and improvement of cell enzyme secretion were the mechanisms for CUO-MBR performance. Therefore, the integrated CUO-MBR was the promising technology for advanced treatment in engineering applications. PMID:25936898

  16. Continuous esterification to produce biodiesel by SPES/PES/NWF composite catalytic membrane in flow-through membrane reactor: experimental and kinetic studies.

    PubMed

    Shi, Wenying; He, Benqiao; Cao, Yuping; Li, Jianxin; Yan, Feng; Cui, Zhenyu; Zou, Zhiqun; Guo, Shiwei; Qian, Xiaomin

    2013-02-01

    A novel composite catalytic membrane (CCM) was prepared from sulfonated polyethersulfone (SPES) and polyethersulfone (PES) blend supported by non-woven fabrics, as a heterogeneous catalyst to produce biodiesel from continuous esterification of oleic acid with methanol in a flow-through mode. A kinetic model of esterification was established based on a plug-flow assumption. The effects of the CCM structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. The results showed that the CCM structure had a significant effect on the acid conversion. The external mass transfer resistance could be neglected when the flow rate was over 1.2 ml min(-1). The internal mass transfer resistance impacted on the conversion when membrane thickness was over 1.779 mm. An oleic acid conversion kept over 98.0% for 500 h of continuous running. The conversions obtained from the model are in good agreement with the experimental data. PMID:23232226

  17. High temperature catalytically assisted combustion. Final report 1 August 82-28 January 83

    SciTech Connect

    Bracco, F.V.; Royce, B.S.H.; Santavicca, D.A.

    1983-01-28

    Results of research on a two-dimensional, transient catalytic combustion model and on a high-temperature perovskite catalyst are presented. A recently developed two-dimensional, transient model has been used to study the ignition of CO/air mixtures in a platinum coated catalytic honey comb. Comparisons between calculated and measured steady state substrate temperature profiles and exhaust gas compositions show good agreement. A platinum-doped perovskite catalyst has been designed to exhibit low temperature light off and high temperature stability. Preliminary tests using a perovskite powder with one percent by weight platinum are encouraging, showing very little change in surface activity when used with propane fuel.

  18. Ethylene production by ODHE in catalytically modified Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ) membrane reactors.

    PubMed

    Lobera, M Pilar; Escolástico, Sonia; Garcia-Fayos, Julio; Serra, José M

    2012-08-01

    Process intensification by the integration of membranes and high-temperature reactors offers several advantages with regard to conventional process schemes, that is, energy saving, safe operation, reduced plant/unit size, and higher process performance, for example, higher productivity, catalytic activity, selectivity, or stability. We present the study of oxidative dehydrogenation of ethane at 850 °C on a catalytic membrane reactor based on a mixed ionic-electronic conducting membrane. The surface of the membrane made of Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ) has been activated by using different porous catalytic layers based on perovskites. The layer was deposited by screen printing, and the porosity and thickness was studied for the catalyst composition. The different catalyst formulations are based on partial substitution of A- and B-site atoms of doped strontium ferrite/cobaltites (A(0.6)Sr(0.4)Co(0.5)Fe(0.5)O(3-δ) and Ba(0.6)Sr(0.4)BO(3-δ)) and were synthesized by an ethylenediaminetetraacetic acid-citrate complexation route. The use of a disk-shaped membrane in the reactor enabled the direct contact of gaseous oxygen and hydrocarbons to be avoided, and thus, the ethylene content increased. High ethylene yields (up to ≈81 %) were obtained by using a catalytic coating based on Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ), which included macropores produced by the addition of graphite platelets into the screen-printing ink. The promising catalytic results obtained with this catalytically modified membrane reactor are attributed to the combination of 1) the high activity, as a result of the high temperature and oxygen species diffusing through the membrane; 2) the control of oxygen dosing and the low concentration of molecules in the gas phase; and 3) suitable fluid dynamics, which enables appropriate feed contact with the membrane and the rapid removal of products. PMID:22791570

  19. 2011 Alkaline Membrane Fuel Cell Workshop Final Report

    SciTech Connect

    Pivovar, B.

    2012-02-01

    A workshop addressing the current state-of-the-art in alkaline membrane fuel cells (AMFCs) was held May 8-9, 2011, at the Crystal Gateway Marriott in Arlington, Virginia. This workshop was the second of its kind, with the first being held December 11-13, 2006, in Phoenix, Arizona. The 2011 workshop and associated workshop report were created to assess the current state of AMFC technology (taking into account recent advances), investigate the performance potential of AMFC systems across all possible power ranges and applications, and identify the key research needs for commercial competitiveness in a variety of areas.

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

    PubMed

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

    2016-08-01

    Nonoxidative methane dehydroaromatization (MDA: 6CH4 ↔ C6H6 + 9H2) using shape-selective Mo/zeolite catalysts is a key technology for exploitation of stranded natural gas reserves by direct conversion into transportable liquids. However, this reaction faces two major issues: The one-pass conversion is limited by thermodynamics, and the catalyst deactivates quickly through kinetically favored formation of coke. We show that integration of an electrochemical BaZrO3-based membrane exhibiting both proton and oxide ion conductivity into an MDA reactor gives rise to high aromatic yields and improved catalyst stability. These effects originate from the simultaneous extraction of hydrogen and distributed injection of oxide ions along the reactor length. Further, we demonstrate that the electrochemical co-ionic membrane reactor enables high carbon efficiencies (up to 80%) that improve the technoeconomic process viability. PMID:27493179

  1. Combined air stripper/membrane vapor separation systems. Final report

    SciTech Connect

    Wijmans, J.G.; Baker, R.W.; Kamaruddin, H.D.; Kaschemekat, J.; Olsen, R.P.; Rose, M.E.; Segelke, S.V.

    1992-11-01

    Air stripping is an economical and efficient method of removing dissolved volatile organic compounds (VOCs) from contaminated groundwater. Air strippers, however, produce a vent air stream, which must meet the local air quality limits. If the VOC content exceeds the limits, direct discharge is not possible; therefore, a carbon adsorption VOC capture system is used to treat the vent air. This treatment step adds a cost of at least $50/lb of VOC captured. In this program, a combined air stripper/membrane vapor separation system was constructed and demonstrated in the laboratory. The membrane system captures VOCs from the stripper vent stream at a projected cost of $15/lb VOC for a water VOC content of 5 ppmw, and $75/lb VOC for a water VOC content of 1 ppmw. The VOCs are recovered as a small, concentrated liquid fraction for disposal or solvent recycling. The concept has been demonstrated in experiments with a system capable of handling up to 150,000 gpd of water. The existing demonstration system is available for field tests at a DOE facility or remediation site. Replacement of the current short air stripping tower (effective height 3 m) with a taller tower is recommended to improve VOC removal.

  2. Porous Au-Ag Alloy Particles Inlaid AgCl Membranes As Versatile Plasmonic Catalytic Interfaces with Simultaneous, in Situ SERS Monitoring.

    PubMed

    Cao, Qi; Yuan, Kaiping; Liu, Qinghe; Liang, Chongyun; Wang, Xiang; Cheng, Yi-Feng; Li, Qingqing; Wang, Min; Che, Renchao

    2015-08-26

    We present a novel porous Au-Ag alloy particles inlaid AgCl membrane as plasmonic catalytic interfaces with real-time, in situ surface-enhanced Raman spectroscopy (SERS) monitoring. The Au-Ag alloy particles inlaid AgCl membranes were obtained via a facile two-step, air-exposed, and room-temperature immersion reaction with appropriate annealing process. Owing to the designed integration of semiconductor component AgCl and noble metal Au-Ag particles, both the catalytic reduction and visible-light-driven photocatalytic activities toward organic contaminants were attained. Specifically, the efficiencies of about 94% of 4-nitrophenol (4-NP, 5 × 10(-5) M) reduction after 8 min of reaction, and degradation of rhodamine 6G (R6G, 10(-5) M) after 12 min of visible light irradiation were demonstrated. Moreover, efficiencies of above 85% of conversion of 4-NP to 4-aminophenol (4-AP) and 90% of R6G degradation were achieved as well after 6 cycles of reactions, by which robust recyclability was confirmed. Further, with distinct SERS signals generated simultaneously from the surfaces of Au-Ag particles under laser excitation, in situ SERS monitoring of the process of catalytic reactions with superior sensitivity and linearity has been realized. Overall, the capability of the Au-Ag particles inlaid AgCl membranes to provide SERS monitored catalytic and visible-light-driven photocatalytic conversion of organic pollutants, along with their mild and cost-effective fabrication method, would make sense for in-depth understanding of the mechanisms of (photo)catalytic reactions, and also future development of potable, multifunctional and integrated catalytic and sensing devices. PMID:26263301

  3. Catalytic mechanism of hydrogenase from Azotobacter vinelandii. Final technical report, August 1, 1994--July 31, 1997

    SciTech Connect

    Arp, D.J.

    1997-10-01

    This project is focused on investigations of the catalytic mechanism of the hydrogenase found in the aerobic, N{sub 2}-fixing microorganism Azotobacter vinelandii. This report summarizes the progress during the first two years of the current project and include the anticipated course of the research for the remaining year of the current project. Because the current proposal represents a change in direction, the authors also include a brief progress report of prior DOE-sponsored research dealing with hydrogenases.

  4. Catalytic and transport mechanisms of supercritical fuels. Final report, 1 March 1993-15 October 1996

    SciTech Connect

    Moster, W.R.; Ma, Y.H.; Spadaccini, L.

    1996-10-01

    One of the largest scale catalytic processes practiced in the petroleum industry is the cracking of large petroleum molecules into smaller hydrocarbons, primarily in the gasoline range. In the United States, cracking capacity exceeds l0-l5 million barrels per day. However, the efficient conversion of low grade hydrocarbons to engine fuels with the concomitant absorption of large amounts of heat requires high temperature processing in order to overcome the thermodynamic limitations on conversion. Commercial catalytic cracking and reforming catalysts would rapidly deactivate within the order of seconds when applied under the temperatures required to operate an efficient endothermic fuel conversion process. The overall objective of this research is based on developing a good understanding of the mechanism and theoretical aspects of the behavior of fuels processed by catalysts under supercritical conditions to avoid rapid catalyst deactivation. The approach to be used in this research to gain direct mechanistic information relating to this problem is the use of a novel technique which the authors developed for examining catalytic reactions via in-situ spectroscopic methods under supercritical conditions.

  5. Replacement of chemical intensive water treatment processes with energy saving membrane. Final report

    SciTech Connect

    Mickley, M.C.; Goering, S.W.

    1983-11-01

    The project investigated the use of charged ultrafiltration membranes to treat hard water. More specifically, the work was undertaken to (1) make charged ultrafiltration membranes to demonstrate the technical feasibility of the chemical grafting approach; (2) evaluate the market potential for charged ultrafiltration membranes; and (3) evaluate the cost and energy savings for using charged ultrafiltration as compared to lime-based clarification and other treatment methods. The results suggest that chemical grafting is a relatively simple, reproducible and low-cost way to modify existing substrate materials to give them enhanced transport performance. Process studies lead to the identification of good market potential for membrane processes using charged ultrafiltration membranes. Capital and operating costs relative to lime-based clarification are favorable for low- and medium-sized treatment plants. Finally, substantial energy savings are apparent as compared to lime-based precipitation systems which incur substantial energy consumption in the lime production and transportation steps.

  6. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Final report

    SciTech Connect

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

    1995-06-01

    This project has investigated new metal oxide catalysts for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as CO. Significant progress in catalyst development has been made during the course of the project. We have found that fluorite oxides, CeO{sub 2} and ZrO{sub 2}, and rare earth zirconates such as Gd{sub 2}Zr{sub 2}O{sub 7} are active and stable catalysts for reduction Of SO{sub 2} by CO. More than 95% sulfur yield was achieved at reaction temperatures about 450{degrees}C or higher with the feed gas of stoichiometric composition. Reaction of SO{sub 2} and CO over these catalysts demonstrated a strong correlation of catalytic activity with the catalyst oxygen mobility. Furthermore, the catalytic activity and resistance to H{sub 2}O and CO{sub 2} poisoning of these catalysts were significantly enhanced by adding small amounts of transition metals, such as Co, Ni, Co, etc. The resulting transition metal-fluorite oxide composite catalyst has superior activity and stability, and shows promise in long use for the development of a greatly simplified single-step sulfur recovery process to treat variable and dilute SO{sub 2} concentration gas streams. Among various active composite catalyst systems the Cu-CeO{sub 2} system has been extensively studied. XRD, XPS, and STEM analyses of the used Cu-CeO{sub 2} catalyst found that the fluorite crystal structure of ceria was stable at the present reaction conditions, small amounts of copper was dispersed and stabilized on the ceria matrix, and excess copper oxide particles formed copper sulfide crystals of little contribution to catalytic activity. A working catalyst consisted of partially sulfated cerium oxide surface and partially sulfided copper clusters. The overall reaction kinetics were approximately represented by a first order equation.

  7. Catalytic Hydrothermal Gasification of Lignin-Rich Biorefinery Residues and Algae Final Report

    SciTech Connect

    Elliott, Douglas C.; Neuenschwander, Gary G.; Hart, Todd R.; Rotness, Leslie J.; Zacher, Alan H.; Santosa, Daniel M.; Valkenburt, Corinne; Jones, Susanne B.; Tjokro Rahardjo, Sandra A.

    2009-11-03

    This report describes the results of the work performed by PNNL using feedstock materials provided by the National Renewable Energy Laboratory, KL Energy and Lignol lignocellulosic ethanol pilot plants. Test results with algae feedstocks provided by Genifuel, which provided in-kind cost share to the project, are also included. The work conducted during this project involved developing and demonstrating on the bench-scale process technology at PNNL for catalytic hydrothermal gasification of lignin-rich biorefinery residues and algae. A technoeconomic assessment evaluated the use of the technology for energy recovery in a lignocellulosic ethanol plant.

  8. High-Yield Expression of a Catalytically Active Membrane-Bound Protein: Human P450 Oxidoreductase

    PubMed Central

    Sandee, Duanpen

    2011-01-01

    P450 oxidoreductase (POR) is a two-flavin protein that reduces microsomal P450 enzymes and some other proteins. Preparation of active bacterially expressed human POR for biochemical studies has been difficult because membrane-bound proteins tend to interact with column matrices. To reduce column-protein interactions and permit more vigorous washing, human POR lacking 27 N-terminal residues (N-27 POR) was modified to carry a C-terminal Gly3His6-tag (N-27 POR-G3H6). When expressed in Escherichia coli, N-27 POR-G3H6 could be purified to apparent homogeneity by a modified, single-step nickel-nitrilotriacetic acid affinity chromatography, yielding 31 mg POR per liter of culture, whereas standard purification of native N-27 POR required multiple steps, yielding 5 mg POR per liter. Both POR proteins had absorption maxima at 375 and 453 nm and both reduced cytochrome c with indistinguishable specific activities. Using progesterone as substrate for bacterially expressed purified human P450c17, the Michaelis constant for 17α-hydroxylase activity supported by N-27 POR or N-27 POR-G3H6 were 1.73 or 1.49 μm, and the maximal velocity was 0.029 or 0.026 pmol steroids per picomole P450 per minute, respectively. Using 17-hydroxypregnenolone as the P450c17 substrate, the Michaelis constant for 17,20 lyase activity using N-27 POR or N-27 POR-G3H6 was 1.92 or 1.89 μm and the maximal velocity was 0.041 or 0.042 pmol steroid per picomole P450 per minute, respectively. Thus, N-27 POR-G3H6 is equally active as native N-27 POR. This expression and purification system permits the rapid preparation of large amounts of highly pure, biologically active POR and may be generally applicable for the preparation of membrane-bound proteins. PMID:21586563

  9. The identification of an integral membrane, cytochrome c urate oxidase completes the catalytic repertoire of a therapeutic enzyme

    PubMed Central

    Doniselli, Nicola; Monzeglio, Enrico; Dal Palù, Alessandro; Merli, Angelo; Percudani, Riccardo

    2015-01-01

    In living organisms, the conversion of urate into allantoin requires three consecutive enzymes. The pathway was lost in hominid, predisposing humans to hyperuricemia and gout. Among other species, the genomic distribution of the two last enzymes of the pathway is wider than that of urate oxidase (Uox), suggesting the presence of unknown genes encoding Uox. Here we combine gene network analysis with association rule learning to identify the missing urate oxidase. In contrast with the known soluble Uox, the identified gene (puuD) encodes a membrane protein with a C-terminal cytochrome c. The 8-helix transmembrane domain corresponds to DUF989, a family without similarity to known proteins. Gene deletion in a PuuD-encoding organism (Agrobacterium fabrum) abolished urate degradation capacity; the phenotype was fully restored by complementation with a cytosolic Uox from zebrafish. Consistent with H2O2 production by zfUox, urate oxidation in the complemented strain caused a four-fold increase of catalase. No increase was observed in the wild-type, suggesting that urate oxidation by PuuD proceeds through cytochrome c-mediated electron transfer. These findings identify a missing link in purine catabolism, assign a biochemical activity to a domain of unknown function (DUF989), and complete the catalytic repertoire of an enzyme useful for human therapy. PMID:26349049

  10. Facile in situ synthesis of silver nanoparticles on procyanidin-grafted eggshell membrane and their catalytic properties.

    PubMed

    Liang, Miao; Su, Rongxin; Huang, Renliang; Qi, Wei; Yu, Yanjun; Wang, Libing; He, Zhimin

    2014-04-01

    Facile, efficient, and robust immobilization of metal nanostructures on porous bioscaffolds is an interesting topic in materials chemistry and heterogeneous catalysis. This study reports a facile in situ method for the synthesis and immobilization of small silver nanoparticles (AgNPs) at room temperature on natural eggshell membrane (ESM), which presents interwoven fibrous structure and can be used as a unique protein-based biotemplate. Procyanidin (Pro), a typical plant polyphenol extracted from grape seeds and skins, was first grafted onto ESM fibers to serve as both reductant and stabilizer during the synthesis process. As a result, the AgNPs were facilely synthesized and robustly immobilized on the ESM fibers without additional chemical reductant or physical treatments. The morphology and microstructure of the as-prepared AgNPs@Pro-ESM composites were characterized by combined microscopy and spectroscopy technologies. The results indicate that small AgNPs with mean diameter of 2.46 nm were successfully prepared on the Pro-ESM biotemplate. The composites exhibited good catalytic activity toward the reduction of 4-nitrophenol (4-NP). More importantly, these composite catalysts can be easily recovered and reused for more than eight cycles because of their high stability. PMID:24624939

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

    SciTech Connect

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

    1994-11-01

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

  12. Shape-dependent plasma-catalytic activity of ZnO nanomaterials coated on porous ceramic membrane for oxidation of butane.

    PubMed

    Sanjeeva Gandhi, M; Mok, Young Sun

    2014-12-01

    In order to explore the effects of the shape of ZnO nanomaterials on the plasma-catalytic decomposition of butane and the distribution of byproducts, three types of ZnO nanomaterials (nanoparticles (NPs), nanorods (NRs) and nanowires (NWs)) were prepared and coated on multi-channel porous alumina ceramic membrane. The structures and morphologies of the nanomaterials were confirmed by X-ray diffraction method and scanning electron microscopy. The observed catalytic activity of ZnO in the oxidative decomposition of butane was strongly shape-dependent. It was found that the ZnO NWs exhibited higher catalytic activity than the other nanomaterials and could completely oxidize butane into carbon oxides (COx). When using the bare or ZnO NPs-coated ceramic membrane, several unwanted partial oxidation and decomposition products like acetaldehyde, acetylene, methane and propane were identified during the decomposition of butane. When the ZnO NWs- or ZnO NRs-coated membrane was used, however, the formation of such unwanted byproducts except methane was completely avoided, and full conversion into COx was achieved. Better carbon balance and COx selectivity were obtained with the ZnO NWs and NRs than with the NPs. PMID:25195119

  13. Catalytic coal liquefaction. Final technical report, June 1, 1981-May 31, 1984

    SciTech Connect

    Weller, S.W.

    1984-07-01

    Molybdenum catalysts (both supported and unsupported) have been examined in various stages of preparation and use with respect to BET surface area and low temperature oxygen chemisorption. The results are detailed. X-ray diffraction has been used to characterize ammonium molybdate - after calcination, heated in tetralin under nitrogen and after use in an autoclave. Metal salts have been tested for catalytic effects by heating a tetralin-coal mixture (without hydrogen) at a loading of 1% of the coal. Only ammonium heptamolybdate and stannous chloride had a large incremental effect (based on blank runs with tetralin and catalyst without coal). Differences in liquefaction behavior in tubing bombs and in autoclaves are explained by thermodynamic considerations based on the gas to liquid volume in the two cases. (LTN)

  14. Catalytic fabric filtration for simultaneous NO{sub x} and particulate control. Final report

    SciTech Connect

    Weber, G.F.; Dunham, G.E.; Laudal, D.L.; Ness, S.R.; Schelkoph, G.L.

    1994-08-01

    The overall objective of the project proposed was to evaluate the catalyst-coated fabric filter concept for effective control of NO{sub 2} and particulate emissions simultaneously. General goals included demonstrating high removal efficiency of NO{sub x} and particulate matter, acceptable bag and catalyst life, and that process economics show a significant cost savings in comparison to a commercial SCR process and conventional particulate control. Specific goals included the following: reduce NO{sub x} emissions to 60 ppM or less; demonstrate particulate removal efficiency of >99.5%; demonstrate a bag/catalyst life of >1 year; Control ammonia slip to <25 ppM; show that catalytic fabric filtration can achieve a 50% cost savings over conventional fabric filtration and SCR control technology; determine compatibility with S0{sub 2} removal systems; and show that the concept results in a nonhazardous waste product.

  15. Process engineering and economic evaluations of diaphragm and membrane chlorine cell technologies. Final report

    SciTech Connect

    Not Available

    1980-12-01

    The chlor-alkali manufacturing technologies of (1), diaphragm cells (2), current technology membrane cells (3), catalytic cathode membrane cells (4), oxygen-cathode membrane cells and to a lesser extent several other related emerging processes are studied. Comparisons have been made on the two bases of (1) conventional industrial economics, and (2) energy consumption. The current diaphragm cell may have a small economic advantage over the other technologies at the plant size of 544 metric T/D (600 T/D). The three membrane cells all consume less energy, with the oxygen-cathode cell being the lowest. The oxygen-cathode cell appears promising as a low energy chlor-alkali cell where there is no chemical market for hydrogen. Federal funding of the oxygen-cathode cell has been beneficial to the development of the technology, to electrochemical cell research, and may help maintain the US's position in the international chlor-alkali technology marketplace. Tax law changes inducing the installation of additional cells in existing plants would produce the quickest reduction in power consumption by the chlor-alkali industry. Alternative technologies such as the solid polymer electrolyte cell, the coupling of diaphragm cells with fuel cells and the dynamic gel diaphragm have a strong potential for reducing chloralkali industry power consumption. Adding up all the recent and expected improvements that have become cost-effective, the electrical energy required to produce a unit of chlorine by 1990 should be only 50% to 60% of that used in 1970. In the United States the majority of the market does not demand salt-free caustic. About 75% of the electrolytic caustic is produced in diaphragm cells and only a small part of that is purified. This study indicates that unless membrane cell costs are greatly reduced or a stronger demand develops for salt-free caustic, the diaphragm cells will remain competitive. (WHK)

  16. Separation of Olefin/Paraffin Mixtures with Carrier Facilitated Membrane Final Report

    SciTech Connect

    Merkel, T.C.; Blanc, R.; Zeid, J.; Suwarlim, A.; Firat, B.; Wijmans, H.; Asaro, M.; Greene, M.

    2007-03-12

    to improve membrane coating solution stability resulted in the finding that membrane performance loss could be reversed for all poisoning cases except hydrogen sulfide exposure. This discovery offers the potential to extend membrane lifetime through cyclic regeneration. We also found that certain mixed carriers exhibited greater stability in reducing environments than exhibited by silver salt alone. These results offer promise that solutions to deal with carrier poisoning are possible. The main achievement of this program was the progress made in gaining a more complete understanding of the membrane stability challenges faced in the use of facilitated olefin transport membranes. Our systematic study of facilitated olefin transport uncovered the full extent of the stability challenge, including the first known identification of olefin conditioning and its impact on membrane development. We believe that significant additional fundamental research is required before facilitated olefin transport membranes are ready for industrial implementation. The best-case scenario for further development of this technology would be identification of a novel carrier that is intrinsically more stable than silver ions. If the stability problems could be largely circumvented by development of a new carrier, it would provide a clear breakthrough toward finally recognizing the potential of facilitated olefin transport. However, even if such a carrier is identified, additional development will be required to insure that the membrane matrix is a benign host for the olefin-carrier complexation reaction and shows good long-term stability.

  17. Catalytic conversion of light alkanes-proof-of-concept stage -- Phase 6. Final report, February 1--October 31, 1994

    SciTech Connect

    1994-12-31

    During the course of the first three years of the Cooperative Agreement, the authors uncovered a family of metal perhaloporphyrin complexes which had unprecedented activity for the selective air-oxidation of light alkanes to alcohols. The reactivity of light hydrocarbon substrates with air or oxygen was in the order: isobutane > propane > ethane > methane, in accord with their homolytic bond dissociation energies. Isobutane was so reactive that the proof-of-concept stage of a process for producing tert-butyl alcohol from isobutane was begun (Phase 5). It was proposed that as more active catalytic systems were developed (Phases 4, 6), propane, then ethane and finally methane oxidations will move into this stage (Phases 7 through 9). As of this writing, however, the program has been terminated during the later stages of Phase 5 and 6 so that further work is not anticipated. 72 refs.

  18. Norbin Stimulates the Catalytic Activity and Plasma Membrane Localization of the Guanine-Nucleotide Exchange Factor P-Rex1*

    PubMed Central

    Pan, Dingxin; Barber, Mark A.; Hornigold, Kirsti; Baker, Martin J.; Toth, Judit M.; Oxley, David; Welch, Heidi C. E.

    2016-01-01

    P-Rex1 is a guanine-nucleotide exchange factor (GEF) that activates the small G protein (GTPase) Rac1 to control Rac1-dependent cytoskeletal dynamics, and thus cell morphology. Three mechanisms of P-Rex1 regulation are currently known: (i) binding of the phosphoinositide second messenger PIP3, (ii) binding of the Gβγ subunits of heterotrimeric G proteins, and (iii) phosphorylation of various serine residues. Using recombinant P-Rex1 protein to search for new binding partners, we isolated the G-protein-coupled receptor (GPCR)-adaptor protein Norbin (Neurochondrin, NCDN) from mouse brain fractions. Coimmunoprecipitation confirmed the interaction between overexpressed P-Rex1 and Norbin in COS-7 cells, as well as between endogenous P-Rex1 and Norbin in HEK-293 cells. Binding assays with purified recombinant proteins showed that their interaction is direct, and mutational analysis revealed that the pleckstrin homology domain of P-Rex1 is required. Rac-GEF activity assays with purified recombinant proteins showed that direct interaction with Norbin increases the basal, PIP3- and Gβγ-stimulated Rac-GEF activity of P-Rex1. Pak-CRIB pulldown assays demonstrated that Norbin promotes the P-Rex1-mediated activation of endogenous Rac1 upon stimulation of HEK-293 cells with lysophosphatidic acid. Finally, immunofluorescence microscopy and subcellular fractionation showed that coexpression of P-Rex1 and Norbin induces a robust translocation of both proteins from the cytosol to the plasma membrane, as well as promoting cell spreading, lamellipodia formation, and membrane ruffling, cell morphologies generated by active Rac1. In summary, we have identified a novel mechanism of P-Rex1 regulation through the GPCR-adaptor protein Norbin, a direct P-Rex1 interacting protein that promotes the Rac-GEF activity and membrane localization of P-Rex1. PMID:26792863

  19. Preconversion catalytic deoxygenation of phenolic functional groups. Final technical report, September 1, 1989--August 31, 1992

    SciTech Connect

    Kubiak, C.P.

    1992-12-31

    Several new catalysts for phenol deoxygenation by CO were developed in our laboratories during the grant period. The deoxygenation of phenols by CO represents a.novel approach to the upgrading of coal liquids. The deoxygenation of phenols by CO is thermodynamically more favorable and potentially less expensive than current phenol hydrodeoxygenation (HDO) methods. The reaction was not known to be kinetically feasible until our recent discovery of appropriate catalysts. The catalyst precursor [Ir(triphos)({eta}{sup 4{minus}}C{sub 8}H{sub 12})][C1] was found to catalytically deoxygenate phenol and p-cresol. Reactions were conducted with varying amounts of AR-OH (Ar = C{sub 6}H{sub 5}, p-Me-C{sub 6}H{sub 4}), NaO-Ar, and catalyst precursor. In some reactions, triethyl amine was substituted for NaO-Ar to deprotonate the ArOH. All reactions took place at 55{degrees}C so that AR-OH was the solvent One atmosphere of CO was introduced into each reactor. Periodically, gasses were sampled by gas chromatography (GC) to monitor the disappearance of CO and the appearance of CO{sub 2}. After the amount of CO{sub 2} had reached a plateau, organic products were distilled from the reaction mixture and analyzed by high pressure liquid chromatography (HPLC). Significant quantities of arene (benzene or toluene) were obtained. These results are general. Initial use of phenol results in only benzene. Initial use of p-cresol results in only toluene. Control reactions eliminate the catalyst precursor as the source Of CO{sub 2} or arene. No evidence is obtained for diarylcarbonate formation. HPLC and GC data from consistently demonstrated that toluene and CO{sub 2} were the only products obtained from the deoxygenation of p-cresol by CO. These results were extended to a series of variously substituted phenolic and naptholic substrates related to those found in coal liquids.

  20. Final Report: Investigation of Catalytic Pathways for Lignin Breakdown into Monomers and Fuels

    SciTech Connect

    Gluckstein, Jeffrey A; Hu, Michael Z.; Kidder, Michelle; McFarlane, Joanna; Narula, Chaitanya Kumar; Sturgeon, Matthew R

    2010-12-01

    Lignin is a biopolymer that comprises up to 35% of woody biomass by dry weight. It is currently underutilized compared to cellulose and hemicellulose, the other two primary components of woody biomass. Lignin has an irregular structure of methoxylated aromatic groups linked by a suite of ether and alkyl bonds which makes it difficult to degrade selectively. However, the aromatic components of lignin also make it promising as a base material for the production of aromatic fuel additives and cyclic chemical feed stocks such as styrene, benzene, and cyclohexanol. Our laboratory research focused on three methods to selectively cleave and deoxygenate purified lignin under mild conditions: acidolysis, hydrogenation and electrocatalysis. (1) Acidolysis was undertaken in CH2Cl2 at room temperature. (2) Hydrogenation was carried out by dissolving lignin and a rhodium catalyst in 1:1 water:methoxyethanol under a 1 atm H2 environment. (3) Electrocatalysis of lignin involved reacting electrically generated hydrogen atoms at a catalytic palladium cathode with lignin dissolved in a solution of aqueous methanol. In all of the experiments, the lignin degradation products were identified and quantified by gas chromatography mass spectroscopy and flame ionization detection. Yields were low, but this may have reflected the difficulty in recovering the various fractions after conversion. The homogeneous hydrogenation of lignin showed fragmentation into monomers, while the electrocatalytic hydrogenation showed production of polyaromatic hydrocarbons and substituted benzenes. In addition to the experiments, promising pathways for the conversion of lignin were assessed. Three conversion methods were compared based on their material and energy inputs and proposed improvements using better catalyst and process technology. A variety of areas were noted as needing further experimental and theoretical effort to increase the feasibility of lignin conversion to fuels.

  1. Energy Efficient Catalytic Activation of Hydrogen peroxide for Green Chemical Processes: Final Report

    SciTech Connect

    Collins, Terrence J.; Horwitz, Colin

    2004-11-12

    A new, highly energy efficient approach for using catalytic oxidation chemistry in multiple fields of technology has been pursued. The new catalysts, called TAML® activators, catalyze the reactions of hydrogen peroxide and other oxidants for the exceptionally rapid decontamination of noninfectious simulants (B. atrophaeus) of anthrax spores, for the energy efficient decontamination of thiophosphate pesticides, for the facile, low temperature removal of color and organochlorines from pulp and paper mill effluent, for the bleaching of dyes from textile mill effluents, and for the removal of recalcitrant dibenzothiophene compounds from diesel and gasoline fuels. Highlights include the following: 1) A 7-log kill of Bacillus atrophaeus spores has been achieved unambiguously in water under ambient conditions within 15 minutes. 2) The rapid total degradation under ambient conditions of four thiophosphate pesticides and phosphonate degradation intermediates has been achieved on treatment with TAML/peroxide, opening up potential applications of the decontamination system for phosphonate structured chemical warfare agents, for inexpensive, easy to perform degradation of stored and aged pesticide stocks (especially in Africa and Asia), for remediation of polluted sites and water bodies, and for the destruction of chemical warfare agent stockpiles. 3) A mill trial conducted in a Pennsylvanian bleached kraft pulp mill has established that TAML catalyst injected into an alkaline peroxide bleach tower can significantly lower color from the effluent stream promising a new, more cost effective, energy-saving approach for color remediation adding further evidence of the value and diverse engineering capacity of the approach to other field trials conducted on effluent streams as they exit the bleach plant. 4) Dibenzothiophenes (DBTs), including 4,6-dimethyldibenzothiophene, the most recalcitrant sulfur compounds in diesel and gasoline, can be completely removed from model gasoline

  2. Final Report: Computer Simulation of Osmosis and Reverse Osmosis in Structured Membranes

    SciTech Connect

    Sohail Murad

    2012-01-03

    Molecular simulation methods were developed as part of this project to increase our fundamental understanding of membrane based separation systems. Our simulations clarified for example that steric (size) effects had a significant impact on the desalination membranes. Previously it was thought the separation was entirely driven by coulombic force (attractive/repulsive forces at the membrane surfaces). Steric effects played an important role, because salt ions in brackish water are never present alone, but are strongly hydrated which effectively increases their size, and makes it impossible to enter a membrane, while the smaller water molecules can enter more readily. Membrane surface effects did play a role in increasing the flux of water, but not in the separation itself. In addition we also developed simulation methods to study ion exchange, gas separations, and pervaporation. The methods developed were used to once again increase our fundamental understanding of these separation processes. For example our studies showed that when the separation factor of gases in membranes can be significantly affected by the presence of another gas, it is generally because the separation mechanism has changed. For example in the case of nitrogen and carbon dioxide, in their pure state the separation factor is determined by diffusion, while in mixtures it is influenced more by adsorption in the membrane (zeolite in our case) Finally we developed a new technique using the NMR chemical shift to determine intermolecular interactions for mixtures. For polar-nonpolar systems such as Xe dissolved in water we were able to significantly improve the accuracy of gas solubilities, which are very sensitive to the cross interaction between water and Xe.

  3. Hybrid membrane with TiO2 based bio-catalytic nanoparticle suspension system for the degradation of bisphenol-A.

    PubMed

    Hou, Jingwei; Dong, Guangxi; Luu, Belinda; Sengpiel, Robert G; Ye, Yun; Wessling, Matthias; Chen, Vicki

    2014-10-01

    The removal of micropollutant in wastewater treatment has become a key environmental challenge for many industrialized countries. One approach is to use enzymes such as laccase for the degradation of micropollutants such as bisphenol-A. In this work, laccase was covalently immobilized on APTES modified TiO2 nanoparticles, and the effects of particle modification on the bio-catalytic performance were examined and optimized. These bio-catalytic particles were then suspended in a hybrid membrane reactor for BPA removal with good BPA degradation efficiency observed. Substantial improvement in laccase stability was achieved in the hybrid system compared with free laccase under simulated harsh industrial wastewater treatment conditions (such as a wide range of pH and presence of inhibitors). Kinetic study provided insight of the effect of immobilization on the bio-degradation reaction. PMID:25084046

  4. High temperature ceramic membrane reactors for coal liquid upgrading. Final report, September 21, 1989--November 20, 1992

    SciTech Connect

    Tsotsis, T.T.; Liu, P.K.T.; Webster, I.A.

    1992-12-31

    Membrane reactors are today finding extensive applications for gas and vapor phase catalytic reactions (see discussion in the introduction and recent reviews by Armor [92], Hsieh [93] and Tsotsis et al. [941]). There have not been any published reports, however, of their use in high pressure and temperature liquid-phase applications. The idea to apply membrane reactor technology to coal liquid upgrading has resulted from a series of experimental investigations by our group of petroleum and coal asphaltene transport through model membranes. Coal liquids contain polycyclic aromatic compounds, which not only present potential difficulties in upgrading, storage and coprocessing, but are also bioactive. Direct coal liquefaction is perceived today as a two-stage process, which involves a first stage of thermal (or catalytic) dissolution of coal, followed by a second stage, in which the resulting products of the first stage are catalytically upgraded. Even in the presence of hydrogen, the oil products of the second stage are thought to equilibrate with the heavier (asphaltenic and preasphaltenic) components found in the feedstream. The possibility exists for this smaller molecular fraction to recondense with the unreacted heavy components and form even heavier undesirable components like char and coke. One way to diminish these regressive reactions is to selectively remove these smaller molecular weight fractions once they are formed and prior to recondensation. This can, at least in principle, be accomplished through the use of high temperature membrane reactors, using ceramic membranes which are permselective for the desired products of the coal liquid upgrading process. An additional incentive to do so is in order to eliminate the further hydrogenation and hydrocracking of liquid products to undesirable light gases.

  5. The acidic domain of the endothelial membrane protein GPIHBP1 stabilizes lipoprotein lipase activity by preventing unfolding of its catalytic domain.

    PubMed

    Mysling, Simon; Kristensen, Kristian Kølby; Larsson, Mikael; Beigneux, Anne P; Gårdsvoll, Henrik; Fong, Loren G; Bensadouen, André; Jørgensen, Thomas Jd; Young, Stephen G; Ploug, Michael

    2016-01-01

    GPIHBP1 is a glycolipid-anchored membrane protein of capillary endothelial cells that binds lipoprotein lipase (LPL) within the interstitial space and shuttles it to the capillary lumen. The LPL•GPIHBP1 complex is responsible for margination of triglyceride-rich lipoproteins along capillaries and their lipolytic processing. The current work conceptualizes a model for the GPIHBP1•LPL interaction based on biophysical measurements with hydrogen-deuterium exchange/mass spectrometry, surface plasmon resonance, and zero-length cross-linking. According to this model, GPIHBP1 comprises two functionally distinct domains: (1) an intrinsically disordered acidic N-terminal domain; and (2) a folded C-terminal domain that tethers GPIHBP1 to the cell membrane by glycosylphosphatidylinositol. We demonstrate that these domains serve different roles in regulating the kinetics of LPL binding. Importantly, the acidic domain stabilizes LPL catalytic activity by mitigating the global unfolding of LPL's catalytic domain. This study provides a conceptual framework for understanding intravascular lipolysis and GPIHBP1 and LPL mutations causing familial chylomicronemia. PMID:26725083

  6. The acidic domain of the endothelial membrane protein GPIHBP1 stabilizes lipoprotein lipase activity by preventing unfolding of its catalytic domain

    PubMed Central

    Mysling, Simon; Kristensen, Kristian Kølby; Larsson, Mikael; Beigneux, Anne P; Gårdsvoll, Henrik; Fong, Loren G; Bensadouen, André; Jørgensen, Thomas JD; Young, Stephen G; Ploug, Michael

    2016-01-01

    GPIHBP1 is a glycolipid-anchored membrane protein of capillary endothelial cells that binds lipoprotein lipase (LPL) within the interstitial space and shuttles it to the capillary lumen. The LPL•GPIHBP1 complex is responsible for margination of triglyceride-rich lipoproteins along capillaries and their lipolytic processing. The current work conceptualizes a model for the GPIHBP1•LPL interaction based on biophysical measurements with hydrogen-deuterium exchange/mass spectrometry, surface plasmon resonance, and zero-length cross-linking. According to this model, GPIHBP1 comprises two functionally distinct domains: (1) an intrinsically disordered acidic N-terminal domain; and (2) a folded C-terminal domain that tethers GPIHBP1 to the cell membrane by glycosylphosphatidylinositol. We demonstrate that these domains serve different roles in regulating the kinetics of LPL binding. Importantly, the acidic domain stabilizes LPL catalytic activity by mitigating the global unfolding of LPL's catalytic domain. This study provides a conceptual framework for understanding intravascular lipolysis and GPIHBP1 and LPL mutations causing familial chylomicronemia. DOI: http://dx.doi.org/10.7554/eLife.12095.001 PMID:26725083

  7. 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.

  8. Calpain cleavage of the B isoform of Ins(1,4,5)P3 3-kinase separates the catalytic domain from the membrane anchoring domain.

    PubMed Central

    Pattni, Krupa; Millard, Thomas H; Banting, George

    2003-01-01

    Inositol (1,4,5)-trisphosphate [Ins(1,4,5)P3] is one of the key intracellular second messengers in cells and mobilizes Ca2+ stores in the ER (endoplasmic reticulum). Ins(1,4,5)P3 has a short half-life within the cell, and is rapidly metabolized through one of two pathways, one of which involves further phosphorylation of the inositol ring: Ins(1,4,5)P3 3-kinase (IP3-3K) phosphorylates Ins(1,4,5)P3, resulting in the formation of inositol (1,3,4,5)-tetrakisphosphate [Ins(1,3,4,5)P4]. There are three known isoforms of IP3-3K, designated IP3-3KA, IP3-3KB and IP3-3KC. These have differing N-termini, but highly conserved C-termini harbouring the catalytic domain. The three IP3-3K isoforms have different subcellular locations and the B-kinase is uniquely present in both cytosolic and membrane-bound pools. As it is the N-terminus of the B-kinase that differs most from the A- and C-kinases, we have hypothesized that this portion of the protein may be responsible for membrane localization. Although there are no known membrane-targeting protein motifs within the sequence of IP3-3KB, it is found to be tightly associated with the ER membrane. Here, we show that specific regions of the N-terminus of IP3-3KB are necessary and sufficient for efficient membrane localization of the protein. We also report that, in the presence of Ca2+, the kinase domain of IP3-3KB is cleaved from the membrane-anchoring region by calpain. PMID:12906709

  9. Membrane binding of Escherichia coli RNase E catalytic domain stabilizes protein structure and increases RNA substrate affinity.

    PubMed

    Murashko, Oleg N; Kaberdin, Vladimir R; Lin-Chao, Sue

    2012-05-01

    RNase E plays an essential role in RNA processing and decay and tethers to the cytoplasmic membrane in Escherichia coli; however, the function of this membrane-protein interaction has remained unclear. Here, we establish a mechanistic role for the RNase E-membrane interaction. The reconstituted highly conserved N-terminal fragment of RNase E (NRne, residues 1-499) binds specifically to anionic phospholipids through electrostatic interactions. The membrane-binding specificity of NRne was confirmed using circular dichroism difference spectroscopy; the dissociation constant (K(d)) for NRne binding to anionic liposomes was 298 nM. E. coli RNase G and RNase E/G homologs from phylogenetically distant Aquifex aeolicus, Haemophilus influenzae Rd, and Synechocystis sp. were found to be membrane-binding proteins. Electrostatic potentials of NRne and its homologs were found to be conserved, highly positive, and spread over a large surface area encompassing four putative membrane-binding regions identified in the "large" domain (amino acids 1-400, consisting of the RNase H, S1, 5'-sensor, and DNase I subdomains) of E. coli NRne. In vitro cleavage assay using liposome-free and liposome-bound NRne and RNA substrates BR13 and GGG-RNAI showed that NRne membrane binding altered its enzymatic activity. Circular dichroism spectroscopy showed no obvious thermotropic structural changes in membrane-bound NRne between 10 and 60 °C, and membrane-bound NRne retained its normal cleavage activity after cooling. Thus, NRne membrane binding induced changes in secondary protein structure and enzymatic activation by stabilizing the protein-folding state and increasing its binding affinity for its substrate. Our results demonstrate that RNase E-membrane interaction enhances the rate of RNA processing and decay. PMID:22509045

  10. Membrane binding of Escherichia coli RNase E catalytic domain stabilizes protein structure and increases RNA substrate affinity

    PubMed Central

    Murashko, Oleg N.; Kaberdin, Vladimir R.; Lin-Chao, Sue

    2012-01-01

    RNase E plays an essential role in RNA processing and decay and tethers to the cytoplasmic membrane in Escherichia coli; however, the function of this membrane–protein interaction has remained unclear. Here, we establish a mechanistic role for the RNase E–membrane interaction. The reconstituted highly conserved N-terminal fragment of RNase E (NRne, residues 1–499) binds specifically to anionic phospholipids through electrostatic interactions. The membrane-binding specificity of NRne was confirmed using circular dichroism difference spectroscopy; the dissociation constant (Kd) for NRne binding to anionic liposomes was 298 nM. E. coli RNase G and RNase E/G homologs from phylogenetically distant Aquifex aeolicus, Haemophilus influenzae Rd, and Synechocystis sp. were found to be membrane-binding proteins. Electrostatic potentials of NRne and its homologs were found to be conserved, highly positive, and spread over a large surface area encompassing four putative membrane-binding regions identified in the “large” domain (amino acids 1–400, consisting of the RNase H, S1, 5′-sensor, and DNase I subdomains) of E. coli NRne. In vitro cleavage assay using liposome-free and liposome-bound NRne and RNA substrates BR13 and GGG-RNAI showed that NRne membrane binding altered its enzymatic activity. Circular dichroism spectroscopy showed no obvious thermotropic structural changes in membrane-bound NRne between 10 and 60 °C, and membrane-bound NRne retained its normal cleavage activity after cooling. Thus, NRne membrane binding induced changes in secondary protein structure and enzymatic activation by stabilizing the protein-folding state and increasing its binding affinity for its substrate. Our results demonstrate that RNase E–membrane interaction enhances the rate of RNA processing and decay. PMID:22509045

  11. High temperature size selective membranes. Final report, September 1992--March 1995

    SciTech Connect

    1996-02-01

    Availability of a high temperature size selective membrane capable of separating hydrogen from carbon dioxide and other gases is seen as highly desirable from an economic perspective. Preparation of such a membrane is technically very difficult due to the limitations that the high temperature places on materials selection. We have prepared high temperature membranes as thin film composites of a porous Blackglas{trademark} support and a carbon molecular sieve selective film. Porous Blackglail{trademark} supports have been prepared by pyrolysis of a formed mixture of Blackglas{trademark} B-staged precursor and short Carbon fibers. Such supports have the necessary smoothness for use as a membrane support, good mechanical properties, and an appropriate pore size distribution. These supports can be made either in flat sheet form or in a tubular configuration. A carbon molecular sieve layer can be added to the support by repeated coating/pyrolysis with a dilute solution of precursor polymer. The preferred precursors are polyimide or polyamic acid. Crack formation is observed after the first pyrolyses, but these cracks are repaired during later pyrolyses. The final membrane thickness is only 2.5 {mu}m. The permeation flux of the membrane for hydrogen ranges from 8.1 x 10{sup -5} at room temperature to 3.0 x 10{sup -3} cm{sup 3} (STP) cm{sup -2} sec{sup -1} cmHg{sup -1} at 717{degrees}C, and the selectivity for hydrogen over nitrogen from 2.8 to 3.8, and a selectivity for hydrogen over carbon dioxide of 2.4. This selectivity is close to the Knudsen diffusion limit. In a companion study, unsupported carbon molecular sieve films were also prepared under pyrolysis conditions similar to those used for the supported film. Hydrogen adsorption porosimetry at 19.7{degrees}K was used to show that, under appropriate activation or pyrolysis conditions, such films can be prepared which adsorb hydrogen to a much greater extent than carbon dioxide.

  12. The Translocation Domain of Botulinum Neurotoxin A Moderates the Propensity of the Catalytic Domain to Interact with Membranes at Acidic pH

    PubMed Central

    Araye, Anne; Goudet, Amélie; Barbier, Julien; Pichard, Sylvain; Baron, Bruno; England, Patrick; Pérez, Javier; Zinn-Justin, Sophie; Chenal, Alexandre; Gillet, Daniel

    2016-01-01

    Botulinum neurotoxin A (BoNT/A) is composed of three domains: a catalytic domain (LC), a translocation domain (HN) and a receptor-binding domain (HC). Like most bacterial toxins BoNT/A is an amphitropic protein, produced in a soluble form that is able to interact, penetrate and/or cross a membrane to achieve its toxic function. During intoxication BoNT/A is internalized by the cell by receptor-mediated endocytosis. Then, LC crosses the membrane of the endocytic compartment and reaches the cytosol. This translocation is initiated by the low pH found in this compartment. It has been suggested that LC passes in an unfolded state through a transmembrane passage formed by HN. We report here that acidification induces no major conformational change in either secondary or tertiary structures of LC and HN of BoNT/A in solution. GdnHCl-induced denaturation experiments showed that the stability of LC and HN increases as pH drops, and that HN further stabilizes LC. Unexpectedly we found that LC has a high propensity to interact with and permeabilize anionic lipid bilayers upon acidification without the help of HN. This property is downplayed when LC is linked to HN. HN thus acts as a chaperone for LC by enhancing its stability but also as a moderator of the membrane interaction of LC. PMID:27070312

  13. Catalytic synthesis of silicon carbide preceramic polymers: Polycarbosilanes. Final technical report, March 1, 1991--August 31, 1996

    SciTech Connect

    Berry, D.H.

    1997-02-01

    This effort has focused on the development of new systems for the catalytic formation of organosilicon monomers and polymers. Several new classes of ruthenium phosphine complexes containing one, two, or three silicon ligands have been prepared, and which exhibit unique catalytic reactivity for (1) the dehydrogenative coupling of tertiary alkyl silanes to polycarbonsilanes, (2) dehydrogenative coupling of secondary and primary alkyl and aryl silanes to polysilanes, and (3) the dehydrogenative heterocoupling of silanes with substituted arenes to yield aryl silanes. In addition, germanium analogs of the ruthenium silyl complexes have been found to be effective catalysts for the unprecedented demethanative coupling of alkyl germanes to high molecular weight polygermanes. For each of these new reactions, key mechanistic features of the catalytic processes have been elucidated, and the complexes have been extensively studied in terms of relevant stoichiometric reactivity and structural features.

  14. FINAL REPORT:Observation and Simulations of Transport of Molecules and Ions Across Model Membranes

    SciTech Connect

    MURAD, SOHAIL; JAMESON, CYNTHIA J

    2013-10-22

    During the this new grant we developed a robust methodology for investigating a wide range of properties of phospho-lipid bilayers. The approach developed is unique because despite using periodic boundary conditions, we can simulate an entire experiment or process in detail. For example, we can follow the entire permeation process in a lipid-membrane. This includes transport from the bulk aqueous phase to the lipid surface; permeation into the lipid; transport inside the lipid; and transport out of the lipid to the bulk aqueous phase again. We studied the transport of small gases in both the lipid itself and in model protein channels. In addition, we have examined the transport of nanocrystals through the lipid membrane, with the main goal of understanding the mechanical behavior of lipids under stress including water and ion leakage and lipid flip flop. Finally we have also examined in detail the deformation of lipids when under the influence of external fields, both mechanical and electrostatic (currently in progress). The important observations and conclusions from our studies are described in the main text of the report

  15. Novel selective surface flow (SSF{sup TM}) membranes for the recovery of hydrogren from waste gas streams. Final report

    SciTech Connect

    Anand, M.

    1995-08-01

    The waste streams are off-gas streams from various chemical/refinery operations. In Phase I, the architecture of the membrane and the separation device were defined and demonstrated. The system consists of a shell-and-tube separator in which the gas to be separated is fed to the tube side, the product is collected as high pressure effluent and the permeate constitutes the waste/fuel stream. Each tube, which has the membrane coated on the interior, does the separation. A multi- tube separator device containing 1 ft{sup 2} membrane area was built and tested. The engineering data were used for designing a process for hydrogen recovery from a fluid catalytic cracker off-gas stream. First-pass economics showed that overall cost for hydrogen production is reduced by 35% vs on-purpose production of hydrogen by steam- methane reforming. The hydrogen recovery process using the SSF membrane results in at least 15% energy reduction and significant decrease in CO{sub 2} and NO{sub x} emissions.

  16. Cryogenic methane separation/catalytic hydrogasification process analysis. Final technical report, 23 July 1980-23 September 1981

    SciTech Connect

    Klosek, J.; Gramse, C.J.; Tsao, T.R.

    1981-10-20

    In a continuing effort to further optimize the CS/R (Rockwell) Coal Hydrogasification process and the Exxon Catalytic Coal Gasification (CCG) process, DOE extended the contract study, Cryogenic Methane Separation/Catalytic Hydrogasification Process Analysis (ET-78-C-01-3044). Air Products and Chemicals, Inc. was authorized to perform additional trade-off studies which were of interest to DOE, Rockwell, and Exxon as potential capital and operating cost savings for the two, third generation coal gasification processes. The scope of this contract extension was comprised of two (2) subtasks for the CS/R (Rockwell) process and nine (9) subtasks for the Exxon CCG process. A Task I type screening study was performed for all subtasks. The results of the evaluations are summarized below.

  17. Formation and control of fuel-nitrogen pollutants in catalytic combustion of coal-derived gases. Final report

    SciTech Connect

    Walsh, P. M.; Bruno, C.; Santavicca, D. A.; Bracco, F. V.

    1980-02-01

    The objective of this program has been the elucidation of the mechanism of high temperature catalytic oxidation of coal-derived gases, including their individual constituents,and the effects of sulfur and nitrogen impurities. Detailed experimental data were obtained and a two-dimensional model is being developed and tested by comparison with the experimental data. When complete, the model can be used to optimize designs of catalytic combustors. The model at present includes axial and radial diffusion and gas and surface chemical reactions. Measured substrate temperatures are input in lieu of complete coupling of gas and solid energy conservation equations and radiative heat transfer. Axial and radial gas temperature and composition profiles inside a catalyst channel were computed and compared with experimental measurements at the catalyst outlet. Experimental investigations were made of carbon monoxide and medium-Btu gas combustion in the presence of platinum supported on a monolithic Cordierite substrate. Axial profiles of substrate temperature, gas temperature, and gas composition were determined at different gas velocities and equivalence ratios. The effects of H/sub 2/S and NH/sub 3/ in the medium-Btu gas were also investigated. Systems were proposed for making resonance absorption and Raman scattering measurements of gas temperature and/or species concentrations in a catalytic reactor. A new pulsed multipass Raman scattering technique for increasing photon yield from a scattering volume was developed.

  18. Changed membrane integration and catalytic site conformation are two mechanisms behind the increased Aβ42/Aβ40 ratio by presenilin 1 familial Alzheimer-linked mutations.

    PubMed

    Wanngren, Johanna; Lara, Patricia; Ojemalm, Karin; Maioli, Silvia; Moradi, Nasim; Chen, Lu; Tjernberg, Lars O; Lundkvist, Johan; Nilsson, IngMarie; Karlström, Helena

    2014-01-01

    The enzyme complex γ-secretase generates amyloid β-peptide (Aβ), a 37-43-residue peptide associated with Alzheimer disease (AD). Mutations in presenilin 1 (PS1), the catalytical subunit of γ-secretase, result in familial AD (FAD). A unifying theme among FAD mutations is an alteration in the ratio Aβ species produced (the Aβ42/Aβ40 ratio), but the molecular mechanisms responsible remain elusive. In this report we have studied the impact of several different PS1 FAD mutations on the integration of selected PS1 transmembrane domains and on PS1 active site conformation, and whether any effects translate to a particular amyloid precursor protein (APP) processing phenotype. Most mutations studied caused an increase in the Aβ42/Aβ40 ratio, but via different mechanisms. The mutations that caused a particular large increase in the Aβ42/Aβ40 ratio did also display an impaired APP intracellular domain (AICD) formation and a lower total Aβ production. Interestingly, seven mutations close to the catalytic site caused a severely impaired integration of proximal transmembrane/hydrophobic sequences into the membrane. This structural defect did not correlate to a particular APP processing phenotype. Six selected FAD mutations, all of which exhibited different APP processing profiles and impact on PS1 transmembrane domain integration, were found to display an altered active site conformation. Combined, our data suggest that FAD mutations affect the PS1 structure and active site differently, resulting in several complex APP processing phenotypes, where the most aggressive mutations in terms of increased Aβ42/Aβ40 ratio are associated with a decrease in total γ-secretase activity. PMID:24918054

  19. Reactive Separations via a Hydrothermally Stable Hydrogen Selective Membrane. Final Report

    SciTech Connect

    Ciora, R. J.; Liu, P. KT.

    2002-10-29

    In this SBIR Phase I program, we have successfully completed the fabrication of SiC-based hydrogen selective membranes suitable for use as a membrane reactor for steam-methane reforming applications. Hydrothermal stability was performed for selected membrane to demonstrate their stability for appx. 50 hours under the proposed reforming condition. In addition, several mechanistic study was conducted to elucidate the SiC membrane formation mechanism. This understanding will facilitate membrane optimization work to be proposed for the Phase II study. The reaction study was postponed to the Phase II study.

  20. Membrane/distillation hybrid process research and development. Final report, phase II

    SciTech Connect

    Mazanec, T.J.

    1997-07-01

    This report covers work conducted under the grant awarded to BP by DOE in late 1991 entitled {open_quotes}Membrane/Distillation Hybrid Process Research and Development.{close_quotes} The program was directed towards development and commercialization of the BP process for separation of vapor phase olefins from non-olefins via facilitated transport using an aqueous facilitator. The program has come to a very successful conclusion, with formation of a partnership between BP and Stone and Webster Engineering Corporation (SWEC) to market and commercialize the technology. The focus of this report is the final portion of the program, during which engineering re-design, facilitator optimization, economic analysis, and marketing have been the primary activities. At the end of Phase II BP was looking to partner with an engineering firm to advance the selective olefin recovery (SOR) technology from the lab/demo stage to full commercialization. In August 1995 BP and SWEC reached an agreement to advance the technology by completing additional Phase III work with DOE and beginning marketing activities.

  1. Lower net pressure reverse osmosis membranes and systems - cost and performance advantages and limitations. Final report

    SciTech Connect

    Kremen, S.S.; Hull, C.E.; Jhawar, M.

    1982-06-01

    Reverse osmosis systems are generally designed and utilized on the basis of reference membrane water flux and desalting performance at 400 psi net driving pressure (NDP). Membranes now being offered and tested at a preliminary commercial stage are capable of equivalent performance at 200 psi NDP. These membranes offer immediately obvious savings in energy costs for reverse osmosis desalting and water reclamation. In addition, they can make a most important contribution to reduced membrane replacement costs and improved permeate quality when operating on high salinity feeds at higher recovery levels. A number of hypothetical cases were developed and tabulated, assuming a 200 psi NDP sea water membrane was available. Substantial benefits could be expected if such a membrane could be developed and reduced to practice. Additional cost savings and performance improvements can be realized by operating the 200 psi NDP membranes at somewhat higher applied pressures which preserve or enhance NDP.

  2. Membrane ultrafiltration of sulfonates and oil from micellar flooding wastewaters. Final report

    SciTech Connect

    Dubey, S.; Perez, N.L.; Ramakrishnan, B.; Thompson, R.E.

    1981-09-01

    Two membrane ultrafilters were tested with simulated micellar-flood wastewaters. The waters were brine containing oil, sulfonate, butyl alcohol, and polymer. Two sulfonates, one essentially oil-soluble and one essentially water-soluble, were used. The polymer used was polyacrylamide, except for a few runs done with xanthan gum. The membranes produced permeates containing very little oil, sulfonate or polymer. The butyl alcohol apparently passed through quantitatively. The cellulosic membrane tested was more effective than the polymeric membrane in that it gave better flux rates and was easier to clean when fouled. A field sample was run with the cellulosic membrane. The field sample contained crude-oil sulfonate which, unlike the commercial surfactants used in the simulated wastewaters, passed through the membrane almost quantitatively. Membrane ultrafiltration will not be of use in purifying water containing such sulfonates.

  3. Crystallization and preliminary X-ray crystallographic analysis of the catalytic domain of membrane type 1 matrix metalloproteinase

    PubMed Central

    Ogata, Hideaki; Decaneto, Elena; Grossman, Moran; Havenith, Martina; Sagi, Irit; Lubitz, Wolfgang; Knipp, Markus

    2014-01-01

    Membrane type 1 matrix metalloproteinase (MT1-MMP) belongs to the large family of zinc-dependent endopeptidases termed MMPs that are located in the extracellular matrix. MT1-MMP was crystallized at 277 K using the vapour-diffusion method with PEG as a precipitating agent. Data sets for MT1-MMP were collected to 2.24 Å resolution at 100 K. The crystals belonged to space group P43212, with unit-cell parameters a = 62.99, c = 122.60 Å. The crystal contained one molecule per asymmetric unit, with a Matthews coefficient (V M) of 2.90 Å3 Da−1; the solvent content is estimated to be 57.6%. PMID:24637763

  4. A Broad Spectrum Catalytic System for Removal of Toxic Organics from Water by Deep Oxidation - Final Report

    SciTech Connect

    Sen, Ayusman

    2000-12-01

    A most pressing need for the DOE environmental management program is the removal of toxic organic compounds present in groundwater and soil at specific DOE sites. While several remediation procedures have been proposed, they suffer from one or more drawbacks. The objective of the present research was to develop new catalytic procedures for the removal of toxic organic compounds from the environment through their deep oxidation to harmless products. In water, metallic palladium was found to catalyze the deep oxidation of a wide variety of toxic organic compounds by dioxygen at 80-90 C in the presence of carbon monoxide or dihydrogen. Several classes of organic compounds were examined: benzene, phenol and substituted phenols, nitro and halo organics, organophosphorus, and organosulfur compounds. In every case, deep oxidation to carbon monoxide, carbon dioxide, and water occurred in high yields, resulting in up to several hundred turnovers over a 24 hour period. For substrates susceptible to hydrogenation, the conversions were generally high with dihydrogen than with carbon monoxide. It is clear from the results obtained that we have discovered an exceptionally versatile catalytic system for the deep oxidation of toxic organic compounds in water. This system possesses several attractive features not found simultaneously in other reported systems. These are (a) the ability to directly utilize dioxygen as the oxidant, (b) the ability to carry out the deep oxidation of a particularly wide range of functional organics, and (c) the ease of recovery of the catalyst by simple filtration.

  5. Catalytic Two-Stage Liquefaction (CTSL) process bench studies with bituminous coal. Final report, [October 1, 1988--December 31, 1992

    SciTech Connect

    Comolli, A.G.; Johanson, E.S.; Karolkiewicz, W.F.; Lee, L.K.; Stalzer, R.H.; Smith, T.O.

    1993-03-01

    Reported herein are the details and results of Laboratory and Bench-Scale experiments using bituminous coal concluded at Hydrocarbon Research, Inc., under DOE contract during the period October 1, 1988 to December 31, 1992. The work described is primarily concerned with the application of coal cleaning methods and solids separation methods to the Catalytic Two-Stage Liquefaction (CTSL) Process. Additionally a predispersed catalyst was evaluated in a thermal/catalytic configuration, and an alternative nickel molybdenum catalyst was evaluated for the CTSL process. Three coals were evaluated in this program: Bituminous Illinois No. 6 Burning Star and Sub-bituminous Wyoming Black Thunder and New Mexico McKinley Mine seams. The results from a total of 16 bench-scale runs are reported and analyzed in detail. The tests involving the Illinois coal are reported herein, and the tests involving the Wyoming and New Mexico coals are described in Topical Report No. 1. On the laboratory scale, microautoclave tests evaluating coal, start-up oils, catalysts, thermal treatment, CO{sub 2} addition and sulfur compound effects are reported in Topical Report No. 3. Other microautoclave tests, such as tests on rejuvenated catalyst, coker liquids, and cleaned coals, are described in the Bench Run sections to which they refer. The microautoclave tests conducted for modelling the CTSL process are described in the CTSL Modelling section of Topical Report No. 3 under this contract.

  6. Chimaeras reveal the role of the catalytic core in the activation of the plasma membrane Ca2+ pump.

    PubMed

    Ba-Thein, W; Caride, A J; Enyedi, A; Pászty, K; Croy, C L; Filoteo, A G; Penniston, J T

    2001-05-15

    Isoform 2b of the plasma membrane calcium pump differs from the ubiquitous isoform 4b in the following: (a) higher basal activity in the absence of calmodulin; (b) higher affinity for calmodulin; and (c) higher affinity for Ca(2+) in the presence of calmodulin [Elwess, Filoteo, Enyedi and Penniston (1997) J. Biol. Chem. 272, 17981-17986]. To investigate which parts of the molecule determine these kinetic differences, we made four chimaeric constructs in which portions of isoform 2b were grafted into isoform 4b: chimaera I contains only the C-terminal regulatory region of isoform 2b; chimaera II contains the N-terminal moiety of isoform 2b, including both cytoplasmic loops; chimaera III contains the sequence of isoform 2b starting from the N-terminus to after the end of the first (small) cytoplasmic loop; and chimaera IV contains only the second (large) cytoplasmic loop. Surprisingly, chimaera I showed low basal activity in the absence of calmodulin and low affinity for calmodulin, unlike isoform 2b. In contrast, the chimaera containing both loops showed high basal activity, and Ca(2+) activation curves (both in the absence and in the presence of calmodulin) similar to those of isoform 2b. The rates of activation by calmodulin and of inactivation by calmodulin removal were measured, and the apparent K(d) for calmodulin was calculated from the ratio between these rate constants. The order of affinity was: 2b=II>4b=IV>III=I. From these results it is clear that the construct that most closely resembles isoform 2b is chimaera II. This shows that, in order to obtain an enzyme with properties similar to those of isoform 2b, both cytoplasmic loops are needed. PMID:11336657

  7. FY05 LDRD Final Report Molecular Engineering of Electrodialysis Membranes 03-ERD-060

    SciTech Connect

    Bourcier, W; O'Brien, K; Sawvel, A; Johnson, M; Bettencourt, K; Letant, S; Felter, T; Langry, K; Wilson, B; Haslam, J; Schaldach, C; Sopchak, D

    2006-02-22

    Using a combination of modeling and experimental work we have developed a new method for purifying water that uses less energy than conventional methods and that can be made selective for removing targeted contaminants. The method uses nanoporous membranes that are permselective for anion or cation transfer. Ion selectivity results from double layer overlap inside the pores such that they dominantly contain ions opposite in charge to the surface charge of the membrane. Membrane charge can be adjusted through functionalization. Experiments confirm membrane permselectivity and overall energy use less than that for conventional electrodialysis. The nanoporous membranes are used in a conventional electrodialysis configuration and can be incorporated in existing electrodialysis systems without modification. The technology merits further development and testing in real systems, and could result in a significant reduction in water treatment costs.

  8. Technical and economic feasibility of membrane technology. Final report, September 17, 1979-November 16, 1981

    SciTech Connect

    Not Available

    1981-01-01

    The first phase of the project involved the development of a literature survey relative to the state-of-the-art for reverse osmosis (RO), electrodialysis (ED), and ultra filtration (UF). A comprehensive examination of both domestic and foreign literature provided a basis for selection of membrane candidates evaluated in Phase II and III of the project. In addition, an investigation was conducted identifying the development of other commercial membrane materials for use other than in the sugar industry (cheese industry). During Phase II, selected membranes were evaluated using a prototype mounting configuration, different temperatures, pressures, feed streams as well as some preliminary testing on ED and UF. The feed streams evaluated included diffusion juice, thin juice, hot Steffan waste, and ion exchanged purified effluents. Replicated runs were performed on several different batches of membranes and feeds to establish significant differences. The activity conducted during Phase III consisted of evaluating selected membranes over a long-term performance basis, i.e., pilot plant evaluation. Membrane material were mounted in pilot hardware for testing purposes. Determinations of membrane life cycles were made as well as establishing the preliminary economics of the operation as related to replacement module service life and on-line operating characteristics.

  9. Final Report - Energy Reduction and Advanced Water Removal via Membrane Solvent Extraction Technology

    SciTech Connect

    Reed, John; Fanselow, Dan; Abbas, Charles; Sammons, Rhea; Kinchin, Christopher

    2014-08-06

    3M and Archer Daniels Midland (ADM) collaborated with the U.S. Department of Energy (DOE) to develop and demonstrate a novel membrane solvent extraction (MSE) process that can substantially reduce energy and water consumption in ethanol production, and accelerate the fermentation process. A cross-flow membrane module was developed, using porous membrane manufactured by 3M. A pilot process was developed that integrates fermentation, MSE and vacuum distillation. Extended experiments of 48-72 hours each were conducted to develop the process, verify its performance and begin establishing commercial viability.

  10. Pre-steady-state kinetic study of the effects of K+ on the partial reactions of the catalytic cycle of the plasma membrane Ca(2+)-ATPase.

    PubMed Central

    Herscher, C J; Rega, A F; Adamo, H P

    1996-01-01

    The effects of 100 mM K+ on the partial reactions that take place during ATP hydrolysis on the calcium ion-dependent ATPase from plasma membrane (PM-Ca(2+)-ATPase) were studied at 37 degrees C on fragmented intact membranes from pig red cells by means of a rapid chemical quenching technique. At 10 microM [gamma-32P]ATP plus non-limiting concentrations of Ca2+ and Mg2+, K+ increased the k(app) of formation by 140% to 84 11 s-1 and the steady-state level of phosphoenzyme (EP) by 25% to 3.4 0.17 pmol/mg of protein. If added together with [gamma-32P]ATP at the beginning of phosphorylation, K+ was much less effective than if added earlier, indicating that it did not act on the phosphorylation reaction. Measurements of the E2 --> E1 transition by phosphorylation showed that in medium with Ca2+ and Mg2+, K+ increased the k(app) of the transition by 55% to 14 3 s-1 and the apparent concentration of E1 by 45%, suggesting that this may be the cause of the increased rate of phosphorylation observed in enzyme preincubated with K+. The presence of K+ did not change the slow decay of EP without Mg2+ but activated the decay of EP made with Mg2+, increasing its k(app) by 60% to 91 12 s-1. In contrast with observations made during phosphorylation, if added at the beginning of dephosphorylation K+ was fully effective in favouring decomposition of EP made in medium containing no K+. In the presence of either 3mM ATP or 3 mM ATP plus calmodulin, which activate hydrolysis of CaE2P, the effect of K+ on dephosphorylation was conserved. Because the sites for K+ are intracellular and the concentration of K+ in normal red cells is above 100 mM, the effects described here must be taken into account to describe the catalytic cycle of the PM-Ca(2+)-ATPase under physiological conditions. PMID:8615846

  11. Treatment of membrane surfaces with oriented monolayers for improved renovation of impaired water. Final report

    SciTech Connect

    Speaker, L.M.; Russo, G.M.; Quinn, K.B.; Wolf, B.L.; Whitt, T.P.

    1991-04-21

    AFT (antifouling technology) for separatory membranes was initially demonstrated in 1981. The effort summarized here was designed to test AFT against humates and alternative foulants, enhancing the fundamental understanding of fouling and fouling propensity. Investigator surface-modified membranes with Langmuir-Blodgett (LB) films (oriented monomolecular films) and monitored responses of selectivities and throughputs to challenges. The materials bank included 18 surfactants, five different types of separatory membranes, and 15 likely foulants. At least 300 membranes were surface-modified and their permeation characteristics followed in more than 150 computer-controlled 23-h challenges, in most cases with aqueous sodium humate. LB-system vibration problems may have compromised the quality and fouling resistance of some coatings. Both selectivities and cumulative permeate volumes of membranes LB-coated with 11-perfluorohexyl undecanoic acid, 11-perfluoroheptyl undecanyl pyridinium bromide, and 11-perfluorooctyl undecanyl pyridinium bromide were superior to those of controls, indicating that LB treatment had simultaneously increased both selectivity and fouling-resistance. More data is being analyzed; as the database expands, investigators expect to contribute to the mechanisitic understanding of fouling and fouling prevention, as well as developing selection criteria for the best (least fouling) combinations of AFT treatment, membrane, and feed stream.

  12. Facilitated transport ceramic membranes for high-temperature gas cleanup. Final report, February 1990--April 1994

    SciTech Connect

    Quinn, R.; Minford, E.; Damle, A.S.; Gangwal, S.K.; Hart, B.A.

    1994-04-01

    The objective of this program was to demonstrate the feasibility of developing high temperature, high pressure, facilitated transport ceramic membranes to control gaseous contaminants in Integrated Gasification Combined Cycle (IGCC) power generation systems. Meeting this objective requires that the contaminant gas H{sub 2}S be removed from an IGCC gas mixture without a substantial loss of the other gaseous components, specifically H{sub 2} and CH{sub 4}. As described above this requires consideration of other, nonconventional types of membranes. The solution evaluated in this program involved the use of facilitated transport membranes consisting of molten mixtures of alkali and alkaline earth carbonate salts immobilized in a microporous ceramic support. To accomplish this objective, Air Products and Chemicals, Inc., Golden Technologies Company Inc., and Research Triangle Institute worked together to develop and test high temperature facilitated membranes for the removal of H{sub 2}S from IGCC gas mixtures. Three basic experimental activities were pursued: (1) evaluation of the H{sub 2}S chemistry of a variety of alkali and alkaline earth carbonate salt mixtures; (2) development of microporous ceramic materials which were chemically and physically compatible with molten carbonate salt mixtures under IGCC conditions and which could function as a host to support a molten carbonate mixture and; (3) fabrication of molten carbonate/ceramic immobilized liquid membranes and evaluation of these membranes under conditions approximating those found in the intended application. Results of these activities are presented.

  13. Direct catalytic conversion of methane and light hydrocarbon gases. Final report, October 1, 1986--July 31, 1989

    SciTech Connect

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

    1995-06-01

    This project explored conversion of methane to useful products by two techniques that do not involve oxidative coupling. The first approach was direct catalytic dehydrocoupling of methane to give hydrocarbons and hydrogen. The second approach was oxidation of methane to methanol by using heterogenized versions of catalysts that were developed as homogeneous models of cytochrome-P450, an enzyme that actively hydroxylates hydrocarbons by using molecular oxygen. Two possibilities exist for dehydrocoupling of methane to higher hydrocarbons: The first, oxidative coupling to ethane/ethylene and water, is the subject of intense current interest. Nonoxidative coupling to higher hydrocarbons and hydrogen is endothermic, but in the absence of coke formation the theoretical thermodynamic equilibrium yield of hydrocarbons varies from 25% at 827{degrees}C to 65% at 1100{degrees}C (at atmospheric pressure). In this project we synthesized novel, highly dispersed metal catalysts by attaching metal clusters to inorganic supports. The second approach mimics microbial metabolism of methane to produce methanol. The methane mono-oxygenase enzyme responsible for the oxidation of methane to methanol in biological systems has exceptional selectivity and very good rates. Enzyme mimics are systems that function as the enzymes do but overcome the problems of slow rates and poor stability. Most of that effort has focused on mimics of cytochrome P-450, which is a very active selective oxidation enzyme and has a metalloporphyrin at the active site. The interest in nonporphyrin mimics coincides with the interest in methane mono-oxygenase, whose active site has been identified as a {mu}-oxo dinuclear iron complex.We employed mimics of cytochrome P-450, heterogenized to provide additional stability. The oxidation of methane with molecular oxygen was investigated in a fixed-bed, down-flow reactor with various anchored metal phthalocyanines (PC) and porphyrins (TPP) as the catalysts.

  14. A novel approach to highly dispersing catalytic materials in coal for gasification. Final technical report, September 1989--November 1992

    SciTech Connect

    Abotsi, G.M.K.; Bota, K.B.

    1992-12-01

    The objectives of this project were to investigate the effects of coal surface charge on the uptake of aqueous soluble metal catalysts from solution and to determine the influence of the interfacial interaction on char reactivity. Another goal is to assess the potential of using potassium carbonate, potassium acetate or their mixtures as catalysts for char gasification. The lower cost and the high catalytic activity of the latter compound will produce economic benefits by reducing the amount of potassium carbonate required for efficient char reactivities on a commercial scale. To minimize the interference of the coals` inherent inorganic materials with the added calcium or potassium, the gasification studies were restricted to the demineralized coals. In a manner similar to the effect of pH on the surface electrochemistry of the coals, the reactivities of the calcium- or potassium-loaded chars in bon dioxide at 800{degree}C were dependent upon the pH at which the catalysts were ion-exchanged onto the coals. For the calcium-containing chars, the reactivities increased in the order: pH 6 > pH 10 > pH 1. In contrast, the variation of the gasification rates with potassium loading pH was: pH 6 {approximately} pH 10 {much_gt} pH 1. However, simultaneous adsorption of the metals at {approximately} pH 1 enhanced char reactivity relative to metals loading at pH 6 or 10. These findings are attributed to the differences in the extent of electrostatic interaction between the calcium or potassium ions and the charged coal surface during catalyst loading from solution.

  15. Superior catalysts for selective catalytic reduction of nitric oxide. Final technical report, October 1, 1993--September 30, 1995

    SciTech Connect

    Yang, R.T.; Li, W.B.; Chen, J.P.; Hausladen, M.C.; Cheng, L.S.; Kikkinides, E.S.

    1995-12-31

    The most advanced and proven technology for NO{sub x} control for stationary sources is Selective Catalytic Reduction (SCR). In SCR, NO{sub x} is reduced by NH{sub 3} to N{sub 2} and H{sub 2}O. The commercial catalysts are based on V{sub 2}O{sub 5}/TiO{sub 2}, and the vanadium-based catalysts are patented by the Japanese (Mitsubishi). However, there are three main advantages for the vanadium-based SCR catalyst: (a) a tendency to be poisoned in the flue gas; (b) oxidation of SO{sub 2} to SO{sub 3} by V{sub 2}O{sub 5}, this is a particularly severe problem due to the higher sulfur content of American coals compared with coals used in Japan (from Australia) and in Europe; (c) environmental problems involved in the disposal of the spent catalyst (due to the toxicity of vanadium). In order to overcome these problems, in addition to the undesirable dominance by the Japanese patent position, the authors have studied in this project a new type of catalyst for the SCR reaction; namely, pillared clays, which have adjustable, unique structures and acidity. Three types of catalysts were developed and tested for this reaction, i.e. Fe{sub 2}O{sub 3}-pillared clays, delaminated Fe{sub 2}O{sub 3}-pillared clays, and ion-exchanged pillared clays. The project was divided into sixteen tasks, and will be reported as such.

  16. LDRD final report on nano-scale engineering of smart membranes

    SciTech Connect

    Loy, D.A.; Jamison, G.M.; Assink, R.A.

    1997-09-01

    A new approach to the fabrication of porous, amorphous inorganic membranes using organic pore templates was investigated. The pore templates were a new family of hybrid organic-inorganic monomers. As background for membrane work, the monomers were polymerized by sol-gel techniques to make crosslinked polymers. Molecular modeling was used to create computer simulations of the materials and provide insight into their composites, were then converted into porous silicas using low temperature oxygen plasma techniques. A select few of the monomers were copolymerized with silica monomers to form non-porous thin films on mesoporous substrates. The films were converted into porous silica thin films with thermal oxidations and the resulting membranes were tested for gas selectivities and flux.

  17. Silica membranes for hydrogen separation in coal gas processing. Final report, January 1993

    SciTech Connect

    Gavalas, G.R.

    1993-03-01

    The general objective of this project was to synthesize permselective membranes suitable for hydrogen separation from coal gas. The specific objectives were: (i) to synthesize membranes by chemical vapor deposition (CVD) of SiO{sub 2} or other oxides on porous support tubes, (ii) characterize the membranes by permeation measurements of various gases and by electron microscopy, and (iii) obtain information about the mechanism and kinetics Of SiO{sub 2} deposition, and model the process of membrane formation. Silica glass and certain other glasses, in dense (nonporous) form, are highly selective to hydrogen permeation. Since this high selectivity is accompanied by low permeability, however, a practical membrane must have a composite structure consisting of a thin layer of the active oxide supported on a porous tube or plate providing mechanical support. In this project the membranes were synthesized by chemical vapor deposition (CVD) of SiO{sub 2}, TiO{sub 2}, Al{sub 2}O{sub 3} and B{sub 2}O{sub 3} layers inside the walls of porous Vycor tubes (5 mm ID, 7 mm OD, 40 {Angstrom} mean pore diameter). Deposition of the oxide layer was carried out using the reaction of SiCl{sub 4} (or TiCl{sub 4}, AlCl{sub 3}, BCl{sub 3}) and water vapor at elevated temperatures. The porous support tube was inserted concentrically into a larger quartz tube and fitted with flow lines and pressure gauges. The flow of the two reactant streams was regulated by mass flow controllers, while the temperature was controlled by placing the reactor into a split-tube electric furnace.

  18. Fluorescence photobleaching measurements of plant membrane viscosity: Effects of environmental stress: Final report

    SciTech Connect

    Breidenbach, R.W.

    1986-11-01

    The primary purpose of this project was to measure the temperature dependence of the fluidity of plant cell membranes by fluorescence photobleaching recovery, and see if there is a change in fluidity at the temperature of chilling injury. For practical reasons, we have concentrated on measurements of the lateral diffusion constant of the lipid analog dil in tomato vacuolar membrane. We have found an apparent change in the diffusion constant of dil near the temperature of chilling injury (approx.12/sup 0/C), but the scatter in the diffusion constants makes it difficult to prove that there is a change. 11 refs.

  19. 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.

  20. SEPARATION OF HAZARDOUS ORGANICS BY LOW PRESSURE REVERSE OSMOSIS MEMBRANES - PHASE II FINAL REPORT

    EPA Science Inventory

    Extensive experimental studies showed that thin-film, composite membranes can be used effectively for the separation of selected hazardous organic compounds. This waste treatment technique offers definite advantages in terms of high solute separations at low pressures (<2MPa) and...

  1. SEPARATION OF HAZARDOUS ORGANICS BY LOW PRESSURE REVERSE OSMOSIS MEMBRANES - PHASE II FINAL REPORT

    EPA Science Inventory

    Extensive experimental studies shoved that thin-film, composite membranes can be used effectively for the separation of selected hazardous organic compounds. his waste treatment technique offers definite advantages in terms of high solute separations at low pressures (<2MPa) and ...

  2. High flux ceramic membrane for hydrogen separation. Final technical progress report

    SciTech Connect

    K. Durai-Swamy

    1999-05-04

    Fuel cells that convert hydrogen to electricity will play an increasingly important role in the generation of future electric power for stationary and transportation sector applications. However, more economic methods to produce hydrogen from fossil fuels are needed. This project addresses the need to develop low cost ceramic membranes for hydrogen separation from reformed fuels.

  3. Molecular-scale studies of single-channel membrane pores : final report.

    SciTech Connect

    Fleming, James Grant; Evans, Kervin O.; Burns, Alan Richard; Swartzentruber, Brian Shoemaker

    2003-10-01

    We present our research results on membrane pores. The study was divided into two primary sections. The first involved the formation of protein pores in free-standing lipid bilayer membranes. The second involved the fabrication via surface micromachining techniques and subsequent testing of solid-state nanopores using the same characterization apparatus and procedures as that used for the protein pores. We were successful in our ability to form leak-free lipid bilayers, to detect the formation of single protein pores, and to monitor the translocation dynamics of individual homogeneous 100 base strands of DNA. Differences in translocation dynamics were observed when the base was switched from adenine to cytosine. The solid state pores (2-5 nm estimated) were fabricated in thin silicon nitride membranes. Testing of the solid sate pores indicated comparable currents for the same size protein pore with excellent noise and sensitivity. However, there were no conditions under which DNA translocation was observed. After considerable effort, we reached the unproven conclusion that multiple (<1 nm) pores were formed in the nitride membrane, thus explaining both the current sensitivity and the lack of DNA translocation blockages.

  4. FINAL REPORT. REAL-TIME BROAD SPECTRUM CHARACTERIZATION OF HAZARDOUS WASTE BY MEMBRANE INTRODUCTION MASS SPECTROMETRY

    EPA Science Inventory

    The goal of this project was to expand the range of chemical species that may be detected by membrane introduction mass spectrometry (MIMS) in environmental, and specifically in Mixed Waste, monitoring and characterization applications. There were three major thrusts to this work...

  5. Novel macrocyclic carriers for proton-coupled liquid membrane transport. Final report

    SciTech Connect

    Lamb, J.D.; Izatt, R.M.; Bradshaw, J.S.; Shirts, R.B.

    1996-08-24

    The objective of this research program is to elucidate the chemical principles which are responsible for the cation selectivity and permeability of liquid membranes containing macrocyclic carriers. Several new macrocyclic carriers were synthesized during the last three year period. In addition, new, more convenient synthetic routes were achieved for several nitrogen-containing bicyclic and tricyclic macrocycles. The cation binding properties of these macrocycles were investigated by potentiometric titration, calorimetric titration, solvent extraction and NMR techniques. In addition, hydrophobic macrocycles were incorporated into dual hollow fiber and other membrane systems to investigate their membrane performance, especially in the proton-coupled transport mode. A study of the effect of methoxyalkyl macrocycle substituents on metal ion transport was completed. A new calorimeter was constructed which made it possible to study the thermodynamics of macrocycle-cation binding to very high temperatures. Measurements of thermodynamic data for the interaction of crown ethers with alkali and alkaline earth cations were achieved to 473 K. Molecular modeling work was begun for the first time on this project and fundamental principles were identified and developed for the establishment of working models in the future.

  6. Demonstration of membrane aeration panels, City of Geneva wastewater treatment plant. Final report

    SciTech Connect

    1995-01-01

    The report describes the design, construction, and testing of membrane aeration panels at the Marsh Creek wastewater treatment plant (WWTP) in Geneva, NY. The operators at the Geneva plant have undertaken a long-term program to upgrade wastewater treatment processes and lower operating costs. The aging mechanical surface aerators at the Marsh Creek treatment plant were replaced by a state-of-the-art membrane panel system. This fine-bubble diffused air system offers higher oxygen transfer efficiency than surface aerators or other types of fine-bubble diffused-air systems. The project had four objectives: to decrease the amount of electricity used at the plant for aeration; to enable the plant`s existing aeration basins to accommodate higher organic loads and/or nitrify the wastewater should the need arise; to provide an event distribution of dissolved oxygen within the aeration basins to enhance biological wastewater treatment activity; and to provide technical data to assess the performance of the membrane panel system versus other forms of wastewater aeration.

  7. Demonstration of membrane aeration panels: City of Geneva Wastewater Treatment Plant. Final report

    SciTech Connect

    1995-01-01

    This report describes the design, construction, and testing of membrane aeration panels at the Marsh Creek wastewater treatment plant (WWTP) in Geneva, NY. The operators at the Geneva plant have undertaken a long-term program to upgrade wastewater treatment processes and lower operating costs. The aging mechanical surface aerators at the Marsh Creek treatment plant were replaced by a state-of-the-art membrane panel system. This fine-bubble diffused air system offers higher oxygen transfer efficiency than surface aerators or other types of fine-bubble diffused-air systems. The project had four objectives: to decrease the amount of electricity used at the plant for aeration; to enable the plant`s existing aeration basins to accommodate higher organic loads and/or nitrify the wastewater should the need arise; to provide an even distribution of dissolved oxygen within the aeration basins to enhance biological wastewater treatment activity; and to provide technical data to assess the performance of the membrane panel system versus other forms of wastewater aeration.

  8. Blood coagulation reactions on nanoscale membrane surfaces

    NASA Astrophysics Data System (ADS)

    Pureza, Vincent S.

    Blood coagulation requires the assembly of several membrane-bound protein complexes composed of regulatory and catalytic subunits. The biomembranes involved in these reactions not only provide a platform for these procoagulant proteins, but can also affect their function. Increased exposure of acidic phospholipids on the outer leaflet of the plasma membrane can dramatically modulate the catalytic efficiencies of such membrane-bound enzymes. Under physiologic conditions, however, these phospholipids spontaneously cluster into a patchwork of membrane microdomains upon which membrane binding proteins may preferentially assemble. As a result, the membrane composition surrounding these proteins is largely unknown. Through the development and use of a nanometer-scale bilayer system that provides rigorous control of the phospholipid membrane environment, I investigated the role of phosphatidylserine, an acidic phospholipid, in the direct vicinity (within nanometers) of two critical membrane-bound procoagulant protein complexes and their respective natural substrates. Here, I present how the assembly and function of the tissue factor˙factor VIIa and factor Va˙factor Xa complexes, the first and final cofactor˙enzyme complexes of the blood clotting cascade, respectively, are mediated by changes in their immediate phospholipid environments.

  9. Membrane vesicles: A simplified system for studying auxin transport. Final technical report

    SciTech Connect

    Goldsmith, M.H.M.

    1989-12-31

    Indoleacetic acid (IAA), the auxin responsible for regulation of growth, is transported polarly in plants. Several different models have been suggested to account for IAA transport by cells and its accumulation by membrane vesicles. One model sees diffusion of IAA driven by a pH gradient. The anion of a lipophilic weak acid like IAA or butyrate accumulates in an alkaline compartment in accord with the size of the pH gradient The accumulation of IAA may be diminished by the permeability of its lipophilic anion. This anion leak may be blocked by NPA. With anion efflux blocked, a gradient of two pH units would support an IAA accumulation of less than 50-fold at equilibrium (2) Another model sees diffusion of IAA in parallel with a saturable symport (IAA{sup {minus}} + nH{sup +}), driven by both the pH gradient and membrane voltage. Such a symport should be highly accumulative, however, with a lipophilic weak acid such as IAA, net diffusive efflux of IAAH whenever IAAHI{sub i} > IAAH{sub o} would constitute a leak. (3) A third model sees a pH change driven IAA uptake and saturable symport enhanced by internal binding sites. Following pH gradient-driven accumulation of IAA, the anion may bind to an intravesicular site, permitting further uptake of IAA. NPA, by blocking anion efflux, enhances this binding. We have reported that membrane vesicles isolated from actively growing plant tissues are a good system for studying the mechanisms involved in the transport and accumulation of auxin.

  10. Cationic exchange membrane for the zinc-ferricyanide battery. Final report

    SciTech Connect

    Pemsler, J.P.; Dempsey, M.D.

    1985-05-01

    In this one year effort of research into supported-liquid-membrane (SLM) separators for the zinc-ferricyanide battery systems, at least one SLM separator (80% LT27/M80 on 0.13 mm PTFE), has been found that approaches the required specifications with separator resistance in the 2 to 3 ohm-cm/sup 2/ range, 1 x 10/sup -3/ mmoles Fe/h-cm/sup 2/ iron transport and 2 x 10/sup -4/ mmoles Zn/h-cm/sup 2/ zinc transport. This separator is still being tested in a 60-cm/sup 2/ zinc-ferricyanide battery and is exhibiting encouraging results.

  11. Photochemical energy conversion by membrane-bound photoredox systems. Final report

    SciTech Connect

    Tollin, G.

    1994-06-16

    This project has received DOE support since July 1, 1978. During this period, 40 papers have been published dealing predominantly with chlorophyll-photosensitized electron transfer reactions in a variety of media (solutions, polymer films, lipid bilayer membranes). The overall theme of this work has been to develop mechanistic strategies f or photochemical energy storage via chlorophyll, using the green plant photosynthetic system as a paradigm for designing in vitro systems. Microheterogeneous lipid vesicle suspensions allow ready application of time-resolved optical spectroscopy to follow the course of light-induced electron transfer processes. Both the yields and the lifetimes of electron transfer products were markedly improved in the vesicle systems. In subsequent studies, this compartmentalization was favorably manipulated by controlling the electrical charge on the membrane surface, by controlling the solubility properties of the acceptors, by varying the lipid composition, by using mediators to create a concentration gradient to carry electrons from within the bilayer to the aqueous medium, and by incorporating secondary electron acceptors into the aqueous phase.

  12. Development of alternative oxygen production source using a zirconia solid electrolyte membrane. Final report

    SciTech Connect

    Suitor, J.W.; Clark, D.J.; Losey, R.W.

    1990-08-01

    The objective of this multiyear effort was the development, fabrication and testing of a zirconia oxygen production module capable of delivering approximately 100 liters/minute (LPM) of oxygen. The work discussed in this report consists of development and improvement of the zirconia cell along with manufacture of cell components, preliminary design of the final plant, additional economic analysis and industrial participation. (VC)

  13. Detail design of a 10.4-m stretched-membrane dish. Phase 2, Final report

    SciTech Connect

    Not Available

    1994-01-01

    This report describes efforts conducted under Tasks 3 and 4 of the second phase of the project to develop a single-element stretched-membrane dish concept to reduce the cost of a high-performance concentrating solar collector. We completed the detailed design for such a collector suitable to drive a 25-kWe Stirling motor generator. The design includes the collectors, optical element, the drive, and support systems. The aperture of the optical element was sized to provide the required energy to the engine based on test data and analytical models of the concentrator receiver, and engine. The design of the optical element was improved based on experience gained from the design, fabrication, and testing of several prototypes.

  14. Negatively Charged Lipid Membranes Catalyze Supramolecular Hydrogel Formation.

    PubMed

    Versluis, Frank; van Elsland, Daphne M; Mytnyk, Serhii; Perrier, Dayinta L; Trausel, Fanny; Poolman, Jos M; Maity, Chandan; le Sage, Vincent A A; van Kasteren, Sander I; van Esch, Jan H; Eelkema, Rienk

    2016-07-20

    In this contribution we show that biological membranes can catalyze the formation of supramolecular hydrogel networks. Negatively charged lipid membranes can generate a local proton gradient, accelerating the acid-catalyzed formation of hydrazone-based supramolecular gelators near the membrane. Synthetic lipid membranes can be used to tune the physical properties of the resulting multicomponent gels as a function of lipid concentration. Moreover, the catalytic activity of lipid membranes and the formation of gel networks around these supramolecular structures are controlled by the charge and phase behavior of the lipid molecules. Finally, we show that the insights obtained from synthetic membranes can be translated to biological membranes, enabling the formation of gel fibers on living HeLa cells. PMID:27359373

  15. Close-coupled Catalytic Two-Stage Liquefaction (CTSL{trademark}) process bench studies. Final report, [October 1, 1988--July 31, 1993

    SciTech Connect

    Comolli, A.G.; Johanson, E.S.; Karolkiewicz, W.F.; Lee, L.K.; Popper, G.A.; Stalzer, R.H.; Smith, T.O.

    1993-06-01

    This is the final report of a four year and ten month contract starting on October 1, 1988 to July 31, 1993 with the US Department of Energy to study and improve Close-Coupled Catalytic Two-Stage Direct Liquefaction of coal by producing high yields of distillate with improved quality at lower capital and production costs in comparison to existing technologies. Laboratory, Bench and PDU scale studies on sub-bituminous and bituminous coals are summarized and referenced in this volume. Details are presented in the three topical reports of this contract; CTSL Process Bench Studies and PDU Scale-Up with Sub-Bituminous Coal-DE-88818-TOP-1, CTSL Process Bench Studies with Bituminous Coal-DE-88818-TOP-2, and CTSL Process Laboratory Scale Studies, Modelling and Technical Assessment-DE-88818-TOP-3. Results are summarized on experiments and studies covering several process configurations, cleaned coals, solid separation methods, additives and catalysts both dispersed and supported. Laboratory microautoclave scale experiments, economic analysis and modelling studies are also included along with the PDU-Scale-Up of the CTSL processing of sub-bituminous Black Thunder Mine Wyoming coal. During this DOE/HRI effort, high distillate yields were maintained at higher throughput rates while quality was markedly improved using on-line hydrotreating and cleaned coals. Solid separations options of filtration and delayed coking were evaluated on a Bench-Scale with filtration successfully scaled to a PDU demonstration. Directions for future direct coal liquefaction related work are outlined herein based on the results from this and previous programs.

  16. A method for the modulation of membrane fluidity: homogeneous catalytic hydrogenation of phospholipids and phospholipids and phospholipid-water model biomembranes.

    PubMed Central

    Chapman, D; Quinn, P J

    1976-01-01

    The fatty acids associated with phospholipids of cell membranes, and particularly their degree of unsaturation, contribute to the fluidity of their structure and hance determine many of their biological properties. We describe a technique for modulating membrane fluidity which consists of hydrogenating the unsaturated double bonds of membrane phospholipids. This has been accomplished using a homogeneous catalyst. The process has been applied to phospholipids in organic solvents, to phospholipids dispersed as multibilayers in aqueous systems, and also to sonicated preparations of phospholipids arranged as single bilayer vesicles. Preliminary experiments have also been performed with biological membranes. These results indicate that the process of homogeneous catalysis for the modulation of lipid fluidity of biological cell membranes may have considerable future biological and biochemical application. PMID:1069280

  17. Hot gas cleanup using ceramic cross flow membrane filters. Final report

    SciTech Connect

    Ciliberti, D.F.; Smeltzer, E.E.; Alvin, M.A.; Keairns, D.L.; Bachovchin, D.M.

    1983-12-01

    The single unresolved technical issue in the commercialization of pressurized fluid-bed combustion (PPBC) for electric power production is the hot gas cleaning problem. In this technology, high-temperature and -pressure (HTHP), dust-laden flue gases from the combustor must be cleaned enough to reduce expansion turbine blade erosion to an economically acceptable level. Additionally, the level of particulate emission must be compatible with the New Source Performance Standards (NSPS) for environmental acceptability. The Department of Energy (DOE) has sponsored a wide range of research and development programs directed at the solution of this problem. These programs were divided into two classifications, one dealing with more advanced concepts where testing was to be done at relatively large scale and a second group of less advanced, novel concepts where the testing was to be carried out at a bench scale. The cross-flow ceramic membrane filter program described in this report is a member of the small-scale, novel concept group.

  18. Design and characterization of a modular membrane protein anchor to functionalize the moss Physcomitrella patens with extracellular catalytic and/or binding activities.

    PubMed

    Morath, Volker; Truong, Dong-Jiunn Jeffery; Albrecht, Florian; Polte, Ingmar; Ciccone, Rosario Adriano; Funke, Louise Friederike; Reichart, Leonie; Wolf, Christopher Guy; Brunner, Andreas-David; Fischer, Katrin; Schneider, Philipp Constantin; Brüggenthies, Johanna Barbara; Fröhlich, Fabian; Wiedemann, Gertrud; Reski, Ralf; Skerra, Arne

    2014-12-19

    Heterologous enzymes and binding proteins were secreted by the moss Physcomitrella patens or anchored extracellularly on its cell membrane in order to functionalize the apoplast as a biochemical reaction compartment. This modular membrane anchoring system utilizes the signal peptide and the transmembrane segment of the somatic embryogenesis receptor-like kinase (SERK), which were identified in a comprehensive bioinformatic analysis of the P. patens genome. By fusing the soluble enzyme NanoLuc luciferase to the signal peptide, its secretion capability was confirmed in vivo. The membrane localization of hybrid proteins comprising the SERK signal peptide, NanoLuc or other functional modules, the SERK transmembrane anchor, and a C-terminal GFP reporter was demonstrated using fluorescence microscopy as well as site-specific proteolytic release of the extracellular enzyme domain. Our membrane anchoring system enables the expression of various functional proteins in the apoplast of P. patens, empowering this photoautotrophic organism for biotechnological applications. PMID:25524107

  19. 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.

  20. Zeolite membrane cascade for tritium extraction and recovery systems

    SciTech Connect

    Borisevich, O.; Demange, D.; Lefebvre, X.; Kind, M.

    2015-03-15

    Membrane separation by zeolite membranes has been proposed as a pre-concentration stage for the tritium extraction from the purge helium of the breeding blanket combined with a final recovery by the catalytic membrane reactor PERMCAT. This fully continuous operation improves the tritium management in fusion machines, minimizing the tritium inventory. For the first time, the permeation measurements for H{sub 2} - He mixtures through a MFI-alumina hollow fibre membrane has been measured for different compositions (0.1 - 20% H{sub 2}) and temperatures. Such a highly permeable membrane, although it shows a limited selectivity, appears attractive for tritium recovery in the blanket. This will imply its operation in a membrane cascade, for which simulation work is ongoing. Mathematically the process is modeled using mass balance equations that can be transformed into the matrix form and solved iteratively assuming a permeate concentration on the first step of iteration, until the separation requirements are fulfilled.

  1. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 2 - hydrogenative and hydrothermal pretreatments and spectroscopic characterization using pyrolysis-GC-MS, CPMAS {sup 13}C NMR and FT-IR

    SciTech Connect

    Chunshan Song; Hatcher, P.G.; Saini, A.K.; Wenzel, K.A.

    1998-01-01

    It has been indicated by DOE COLIRN panel that low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals. As the second volume of the final report, here we summarize our work on spectroscopic characterization of four raw coals including two subbituminous coals and two bituminous coals, tetrahydrofuran (THF)-extracted but unreacted coals, the coals (THF-insoluble parts) that have been thermally pretreated. in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent, and the coals (THF-insoluble parts) that have been catalytically pretreated in the presence of a dispersed Mo sulfide catalyst in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent.

  2. Association with the Plasma Membrane Is Sufficient for Potentiating Catalytic Activity of Regulators of G Protein Signaling (RGS) Proteins of the R7 Subfamily.

    PubMed

    Muntean, Brian S; Martemyanov, Kirill A

    2016-03-25

    Regulators of G protein Signaling (RGS) promote deactivation of heterotrimeric G proteins thus controlling the magnitude and kinetics of responses mediated by G protein-coupled receptors (GPCR). In the nervous system, RGS7 and RGS9-2 play essential role in vision, reward processing, and movement control. Both RGS7 and RGS9-2 belong to the R7 subfamily of RGS proteins that form macromolecular complexes with R7-binding protein (R7BP). R7BP targets RGS proteins to the plasma membrane and augments their GTPase-accelerating protein (GAP) activity, ultimately accelerating deactivation of G protein signaling. However, it remains unclear if R7BP serves exclusively as a membrane anchoring subunit or further modulates RGS proteins to increase their GAP activity. To directly answer this question, we utilized a rapidly reversible chemically induced protein dimerization system that enabled us to control RGS localization independent from R7BP in living cells. To monitor kinetics of Gα deactivation, we coupled this strategy with measuring changes in the GAP activity by bioluminescence resonance energy transfer-based assay in a cellular system containing μ-opioid receptor. This approach was used to correlate changes in RGS localization and activity in the presence or absence of R7BP. Strikingly, we observed that RGS activity is augmented by membrane recruitment, in an orientation independent manner with no additional contributions provided by R7BP. These findings argue that the association of R7 RGS proteins with the membrane environment provides a major direct contribution to modulation of their GAP activity. PMID:26811338

  3. R&D on an Ultra-Thin Composite Membrane for High-Temperature Operation in PEMFC. Final Report

    SciTech Connect

    Yuh, C.-Y.

    2003-10-06

    FuelCell Energy developed a novel high-temperature proton exchange membrane for PEM fuel cells for building applications. The laboratory PEM fuel cell successfully operated at 100-400{supdegree}C and low relative humidity to improve CO tolerance, mitigate water and thermal management challenges, and reduce membrane cost. The developed high-temperature membrane has successfully completed 500h 120C endurance testing.

  4. Research on degradation product and reaction kinetics of membrane electro-bioreactor (MEBR) with catalytic electrodes for high concentration phenol wastewater treatment.

    PubMed

    Wang, Tao; Zhao, Huanping; Wang, Hui; Liu, Botan; Li, Chunqing

    2016-07-01

    The membrane electro-bioreactor (MEBR) is a novel technology, it treats wastewater by combining membrane filtration, electrokinetic phenomena, and biological processes in one reactor. This paper aims to deal with hard biodegradation and high concentration phenol wastewater. Investigating the influence factors such as initial concentration, voltage, pH value, temperature and mixed liquor suspended solids (MLSS) toward phenol degradation process in electrocatalytic process and membrane bioreactor (MBR), and then apply the optimum conditions in the MEBR system. Results of continuous flow experiments demonstrated that MEBR increased the quality of the treated wastewater than conventional MBR. The above technics followed the zero-order reaction kinetics. The removal efficiency of MEBR was about 11.1% higher for phenol than the sum of the two individual processes. With the help of gas chromatography/mass spectrometry (GC-MS), this qualitative analysis looks at the degradation products of phenol generated in MEBR, through which 2,6-di-tert-butyl-p-benzoquinone was confirmed as the main degradation product. PMID:27108366

  5. Correlation between the phospholipids domains of the target cell membrane and the extent of Naja kaouthia PLA(2)-induced membrane damage: evidence of distinct catalytic and cytotoxic sites in PLA(2) molecules.

    PubMed

    Mukherjee, Ashis K

    2007-02-01

    Two phospholipase A(2) (PLA(2)) enzymes (NK-PLA(2)-A and NK-PLA(2)-B) were purified from the venom of the monocled cobra Naja kaouthia. The molecular weights of NK-PLA(2)-A and NK-PLA(2)-B, as estimated by mass spectrometry, were 13,619 and 13,303 Da respectively. Both phospholipases were highly thermostable, had maximum catalytic activity at basic pH, and showed preferential hydrolysis of phosphatidylcholine. Intravenous injection of either PLA(2) up to a dose of 10 mg/kg body weight was non-toxic to mice and did not show neurotoxic symptoms. The N. kaouthia PLA(2)s displayed anticoagulant and cytotoxic activity, but poor hemolytic activity. Both the PLA(2)s were more toxic to Sf9 and Tn cells compared to VERO cells. NK-PLA(2) exhibited selective lysis of wild-type baculovirus-infected Sf9 cells compared to normal cells. Amino acid modification studies and heating experiments suggest that separate sites in the NK-PLA(2) molecules are responsible for their catalytic, anticoagulant and cytotoxic activities. PMID:17127009

  6. Stable closure of the cytoplasmic half-channel is required for efficient proton transport at physiological membrane potentials in the bacteriorhodopsin catalytic cycle.

    PubMed

    Wang, Ting; Oppawsky, Christoph; Duan, Yong; Tittor, Jörg; Oesterhelt, Dieter; Facciotti, Marc T

    2014-04-15

    The bacteriorhodopsin (BR) Asp96Gly/Phe171Cys/Phe219Leu triple mutant has been shown to translocate protons 66% as efficiently as the wild-type protein. Light-dependent ATP synthesis in haloarchaeal cells expressing the triple mutant is 85% that of the wild-type BR expressing cells. Therefore, the functional activity of BR seems to be largely preserved in the triple mutant despite the observations that its ground-state structure resembles that of the wild-type M state (i.e., the so-called cytoplasmically open state) and that the mutant shows no significant structural changes during its photocycle, in sharp contrast to what occurs in the wild-type protein in which a large structural opening and closing occurs on the cytoplasmic side. To resolve the contradiction between the apparent functional robustness of the triple mutant and the presumed importance of the opening and closing that occurs in the wild-type protein, we conducted additional experiments to compare the behavior of wild-type and mutant proteins under different operational loads. Specifically, we characterized the ability of the two proteins to generate light-driven proton currents against a range of membrane potentials. The wild-type protein showed maximal conductance between -150 and -50 mV, whereas the mutant showed maximal conductance at membrane potentials >+50 mV. Molecular dynamics (MD) simulations of the triple mutant were also conducted to characterize structural changes in the protein and in solvent accessibility that might help to functionally contextualize the current-voltage data. These simulations revealed that the cytoplasmic half-channel of the triple mutant is constitutively open and dynamically exchanges water with the bulk. Collectively, the data and simulations help to explain why this mutant BR does not mediate photosynthetic growth of haloarchaeal cells, and they suggest that the structural closing observed in the wild-type protein likely plays a key role in minimizing substrate

  7. Stable Closure of the Cytoplasmic Half-Channel Is Required for Efficient Proton Transport at Physiological Membrane Potentials in the Bacteriorhodopsin Catalytic Cycle

    PubMed Central

    2015-01-01

    The bacteriorhodopsin (BR) Asp96Gly/Phe171Cys/Phe219Leu triple mutant has been shown to translocate protons 66% as efficiently as the wild-type protein. Light-dependent ATP synthesis in haloarchaeal cells expressing the triple mutant is 85% that of the wild-type BR expressing cells. Therefore, the functional activity of BR seems to be largely preserved in the triple mutant despite the observations that its ground-state structure resembles that of the wild-type M state (i.e., the so-called cytoplasmically open state) and that the mutant shows no significant structural changes during its photocycle, in sharp contrast to what occurs in the wild-type protein in which a large structural opening and closing occurs on the cytoplasmic side. To resolve the contradiction between the apparent functional robustness of the triple mutant and the presumed importance of the opening and closing that occurs in the wild-type protein, we conducted additional experiments to compare the behavior of wild-type and mutant proteins under different operational loads. Specifically, we characterized the ability of the two proteins to generate light-driven proton currents against a range of membrane potentials. The wild-type protein showed maximal conductance between −150 and −50 mV, whereas the mutant showed maximal conductance at membrane potentials >+50 mV. Molecular dynamics (MD) simulations of the triple mutant were also conducted to characterize structural changes in the protein and in solvent accessibility that might help to functionally contextualize the current–voltage data. These simulations revealed that the cytoplasmic half-channel of the triple mutant is constitutively open and dynamically exchanges water with the bulk. Collectively, the data and simulations help to explain why this mutant BR does not mediate photosynthetic growth of haloarchaeal cells, and they suggest that the structural closing observed in the wild-type protein likely plays a key role in minimizing

  8. Variability in natural gas fuel composition and its effects on the performance of catalytic combustion systems. Final report for period September 18, 1998 - September 17, 2000

    SciTech Connect

    Ginter, David; Simchick, Chuck; Schlatter, Jim

    2002-03-01

    Natural gas is composed primarily of methane with small amounts of higher hydrocarbons and diluents, which vary by region and over time. Compositions of natural gas from domestic and worldwide sources were surveyed with respect to content of higher hydrocarbons and diluents. The survey showed slight compositional variability between most of the gases, with a small fraction of them containing significantly larger contents of higher hydrocarbons than the mean. As gas-fired turbines will be used for power generation all over the world, they will need to tolerate operation with fuels with a wide variety of compositions, particularly with respect to the concentration of higher hydrocarbons and diluents. Subscale catalytic combustion modules typical of those used in gas turbine power generation with ultra low emissions of pollutants were tested in a subscale test system with natural gas alone and with added known levels of hydrocarbon compounds and diluents. The range of compositions tested contained the range observed in the survey. Test results were used to calculate the effect of composition on catalyst performance. The compositional variability is of little consequence to the catalyst for most of the gases in the survey, including nearly all of the gases delivered in the U.S. To accommodate the remaining gases, the catalyst inlet temperature must be lowered to maintain combustor durability. These results support commercial acceptance of catalytic combustion systems for use in natural gas fired turbines in distributed power generation with ultra low NO{sub x} emissions.

  9. LDRD final report on imaging self-organization of proteins in membranes by photocatalytic nano-tagging.

    SciTech Connect

    Zavadil, Kevin Robert; Shelnutt, John Allen; Sasaki, Darryl Yoshio; Song, Yujiang; Medforth, Craig J.

    2005-11-01

    We have developed a new nanotagging technology for detecting and imaging the self-organization of proteins and other components of membranes at nanometer resolution for the purpose of investigating cell signaling and other membrane-mediated biological processes. We used protein-, lipid-, or drug-bound porphyrin photocatalysts to grow in-situ nanometer-sized metal particles, which reveal the location of the porphyrin-labeled molecules by electron microscopy. We initially used photocatalytic nanotagging to image assembled multi-component proteins and to monitor the distribution of lipids and porphyrin labels in liposomes. For example, by exchanging the heme molecules in hemoproteins with a photocatalytic tin porphyrin, a nanoparticle was grown at each heme site of the protein. The result obtained from electron microscopy for a tagged multi-subunit protein such as hemoglobin is a symmetric constellation of a specific number of nanoparticle tags, four in the case of the hemoglobin tetramer. Methods for covalently linking photocatalytic porphyrin labels to lipids and proteins were also developed to detect and image the self-organization of lipids, protein-protein supercomplexes, and membrane-protein complexes. Procedures for making photocatalytic porphyrin-drug, porphyrin-lipid, and porphyrin-protein hybrids for non-porphyrin-binding proteins and membrane components were pursued and the first porphyrin-labeled lipids was investigated in liposomal membrane models. Our photocatalytic nanotagging technique may ultimately allow membrane self-organization and cell signaling processes to be imaged in living cells. Fluorescence and plasmonic spectra of the tagged proteins might also provide additional information about protein association and membrane organization. In addition, a porphyrin-aspirin or other NSAID hybrid may be used to grow metal nanotags for the pharmacologically important COX enzymes in membranes so that the distribution of the protein can be imaged at the

  10. Medical Devices; Ear, Nose, and Throat Devices; Classification of the Tympanic Membrane Contact Hearing Aid. Final order.

    PubMed

    2016-01-21

    The Food and Drug Administration (FDA) is classifying the tympanic membrane contact hearing aid into class II (special controls). The special controls that will apply to the device are identified in this order and will be part of the codified language for the tympanic membrane contact hearing aid's classification. The Agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device. PMID:26803881

  11. Development of Novel active transport membrane devices. Phase I. Final report, 31 October 1988--31 January 1994

    SciTech Connect

    Laciak, D.V.; Quinn, R.; Choe, G.S.; Cook, P.J.; Tsai, Fu-Jya

    1994-08-01

    The main objective of this program was to identify and develop a technique for fabricating Active Transport Materials (ATM) into lab-scale membrane devices. Air Products met this objective by applying thin film, multilayer fabrication techniques to support the AT material on a substrate membrane. In Phase IA, spiral-wound hollow fiber membrane modules were fabricated and evaluated. These nonoptimized devices were used to demonstrate the AT-based separation of carbon dioxide from methane, hydrogen sulfide from methane, and ammonia from hydrogen. It was determined that a need exists for a more cost efficient and less energy intensive process for upgrading subquality natural gas. Air Products estimated the effectiveness of ATM for this application and concluded that an optimized ATM system could compete effectively with both conventional acid gas scrubbing technology and current membrane technology. In addition, the optimized ATM system would have lower methane loss and consume less energy than current alternative processes. Air Products made significant progress toward the ultimate goal of commercializing an advanced membrane for upgrading subquality natural gas. The laboratory program focused on developing a high performance hollow fiber substrate and fabricating and evaluating ATM-coated lab-scale hollow fiber membrane modules. Selection criteria for hollow fiber composite membrane supports were developed and used to evaluate candidate polymer compositions. A poly(amide-imide), PAI, was identified for further study. Conditions were identified which produced microporous PAI support membrane with tunable surface porosity in the range 100-1000{Angstrom}. The support fibers exhibited good hydrocarbon resistance and acceptable tensile strength though a higher elongation may ultimately be desirable. ATM materials were coated onto commercial and PAI substrate fiber. Modules containing 1-50 fibers were evaluated for permselectivity, pressure stability, and lifetime.

  12. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, 1 January--31 March 1994

    SciTech Connect

    Iglesia, E.; Heinemann, H.; Perry, D.L.

    1994-03-01

    This report describes work in progress on three tasks: (1) Catalytic steam gasification of coals and cokes; (2) Oxidative coupling of methane; and (3) Synthesis and characterization of catalysts. Since Task 1 is complete, a final report has been written. This report describes membrane reactors, cyclic methane conversion reactors, theoretical descriptions of reaction-separation schemes, and time-space relationships in cyclic and membrane reactors, all subtasks of Task 2. Initial studies under Task 3 are briefly described.

  13. 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.

  14. Anesthesiology Devices; Reclassification of Membrane Lung for Long-Term Pulmonary Support; Redesignation as Extracorporeal Circuit and Accessories for Long-Term Respiratory/Cardiopulmonary Failure. Final order.

    PubMed

    2016-02-12

    The Food and Drug Administration (FDA) is issuing a final order to redesignate membrane lung devices for long-term pulmonary support, a preamendments class III device, as extracorporeal circuit and accessories for long-term respiratory/cardiopulmonary failure, and to reclassify the device to class II (special controls) in patients with acute respiratory failure or acute cardiopulmonary failure where other available treatment options have failed, and continued clinical deterioration is expected or the risk of death is imminent. A membrane lung device for long-term pulmonary support (>6 hours) refers to the oxygenator in an extracorporeal circuit used during long-term procedures, commonly referred to as extracorporeal membrane oxygenation (ECMO). Because a number of other devices and accessories are used with the oxygenator in the circuit, the title and identification of the regulation are revised to include extracorporeal circuit and accessories for long-term respiratory/cardiopulmonary failure. Although an individual device or accessory used in an ECMO circuit may already have its own classification regulation when the device or accessory is intended for short-term use (<=6 hours), such device or accessory will be subject to the same regulatory controls applied to the oxygenator (i.e., class II, special controls) when evaluated as part of the ECMO circuit for long-term use (>6 hours). On its own initiative, based on new information, FDA is revising the classification of the membrane lung device for long-term pulmonary support. PMID:26878739

  15. Membrane alterations following toxic chemical insult. Research progress report No. 3 (Final), 15 July 1984-31 January 1988

    SciTech Connect

    Liss, A.

    1988-03-10

    A procaryotic cell system was developed that can be used to determine the toxic action of chemicals acting at the level of the eucaryotic or procaryotic cytoplasmic membrane. Cell wall-less microbes known as mycoplasmas were used. In this current study, two perfluorinated fatty acids (CB and C10) were found to inhibit the growth of the test mycoplasmas. Two apparent activities, cytotoxicity and cytolysis, were observed. At high concentrations (>10 mM), a detergent-like action was noted. At low concentrations (<10 mM), cell death was observed without detectable cell lysis. Altering the cell membrane (the presumed target of the toxic compounds) resulted in altered levels to toxicity. Similar results were obtained when human or murine B-cells were used as the target organism. The toxic action of the perfluorinated fatty acids apparently involves some interaction with the membrane of the cells being treated.

  16. Final Technical Report "Catalytic Hydrogenation of Carbon Monoxide and Olefin Oxidation" Grant number : DE-FG02-86ER13615

    SciTech Connect

    Wayland, B.B.

    2009-08-31

    Title: Catalytic Hydrogenation of Carbon Monoxide and Olefin Oxidation Grant No. DE-FG02-86ER13615 PI: Wayland, B. B. (wayland@sas.upenn.edu) Abstract Development of new mechanistic strategies and catalyst materials for activation of CO, H2, CH4, C2H4, O2, and related substrates relevant to the conversion of carbon monoxide, alkanes, and alkenes to organic oxygenates are central objectives encompassed by this program. Design and synthesis of metal complexes that manifest reactivity patterns associated with potential pathways for the hydrogenation of carbon monoxide through metallo-formyl (M-CHO), dimetal ketone (M-C(O)-M), and dimetal dionyl (M-C(O)-C(O)-M) species is one major focus. Hydrocarbon oxidation using molecular oxygen is a central goal for methane activation and functionalization as well as regioselective oxidation of olefins. Discovery of new reactivity patterns and control of selectivity are pursued through designing new metal complexes and adjusting reaction conditions. Variation of reaction media promotes distinct reaction pathways that control both reaction rates and selectivities. Dimetalloradical diporphyrin complexes preorganize transition states for substrate reactions that involve two metal centers and manifest large rate increases over mono-metalloradical reactions of hydrogen, methane, and other small molecule substrates. Another broad goal and recurring theme of this program is to contribute to the thermodynamic database for a wide scope of organo-metal transformations in a range of reaction media. One of the most complete descriptions of equilibrium thermodynamics for organometallic reactions in water and methanol is emerging from the study of rhodium porphyrin substrate reactions in aqueous and alcoholic media. Water soluble group nine metalloporphyrins manifest remarkably versatile substrate reactivity in aqueous and alcoholic media which includes producing rhodium formyl (Rh-CHO) and hydroxy methyl (Rh-CH2OH) species. Exploratory

  17. Final Technical Report for DOE Grant, number DE-FG02-05ER15701; Probing Surface Chemistry Under Catalytic Conditions: Olefin Hydrogenation,Cyclization and Functionalization.

    SciTech Connect

    Neurock, Matthew

    2011-05-26

    The specific goal of this work was to understanding the catalytic reactions pathways for the synthesis of vinyl acetate over Pd, Au and PdAu alloys. A combination of both experimental methods (X-ray and Auger spectroscopies, low-energy ion scattering (LEIS), low-energy electron diffraction (LEED) and theory (Density Functional Theory (DFT) calculations and Monte Carlo methods under various different reactions) were used to track the surface chemistry and the influence of alloying. The surface intermediates involved in the various reactions were characterized using reflection-absorption infrared spectroscopy and LEED to identify the nature of the surface species and temperature-programmed desorption (TPD) to follow the decomposition pathways and measure heats of adsorption. These results along with those from density functional theoretical calculations were used determine the kinetics for elementary steps. The results from this work showed that the reaction proceeds via the Samanos mechanism over Pd surfaces whereby the ethylene directly couples with acetate to form an acetoxyethyl intermediate that subsequently undergoes a beta-hydride elimination to form the vinyl acetate monomer. The presence of Au was found to modify the adsorption energies and surface coverages of important surface intermediates including acetate, ethylidyne and ethylene which ultimately influences the critical C-H activation and coupling steps. By controlling the surface alloy composition or structure one can begin to control the steps that control the rate and even the mechanism.

  18. Catalytic Two-Stage Liquefaction (CTSL{trademark}) process bench studies and PDU scale-up with sub-bituminous coal. Final report

    SciTech Connect

    Comolli, A.G.; Johanson, E.S.; Karolkiewicz, W.F.; Lee, L.K.T.; Stalzer, R.H.; Smith, T.O.

    1993-03-01

    Reported are the details and results of Laboratory and Bench-Scale experiments using sub-bituminous coal conducted at Hydrocarbon Research, Inc., under DOE Contract No. DE-AC22-88PC88818 during the period October 1, 1988 to December 31, 1992. The work described is primarily concerned with testing of the baseline Catalytic Two-Stage Liquefaction (CTSL{trademark}) process with comparisons with other two stage process configurations, catalyst evaluations and unit operations such as solid separation, pretreatments, on-line hydrotreating, and an examination of new concepts. In the overall program, three coals were evaluated, bituminous Illinois No. 6, Burning Star and sub-bituminous Wyoming Black Thunder and New Mexico McKinley Mine seams. The results from a total of 16 bench-scale runs are reported and analyzed in detail. The runs (experiments) concern process variables, variable reactor volumes, catalysts (both supported, dispersed and rejuvenated), coal cleaned by agglomeration, hot slurry treatments, reactor sequence, on-line hydrotreating, dispersed catalyst with pretreatment reactors and CO{sub 2}/coal effects. The tests involving the Wyoming and New Mexico Coals are reported herein, and the tests involving the Illinois coal are described in Topical Report No. 2. On a laboratory scale, microautoclave tests evaluating coal, start-up oils, catalysts, thermal treatment, CO{sub 2} addition and sulfur compound effects were conducted and reported in Topical Report No. 3. Other microautoclave tests are described in the Bench Run sections to which they refer such as: rejuvenated catalyst, coker liquids and cleaned coals. The microautoclave tests conducted for modelling the CTSL{trademark} process are described in the CTSL{trademark} Modelling section of Topical Report No. 3 under this contract.

  19. 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.

  20. Novel Approaches to Immobilized Heteropoly Acid Systems for High Temperature, Low Relative Humidity Polymer-Type Membranes - Final Report

    SciTech Connect

    Herring, Andrew M; Horan, James L; Aieta, Niccolo V; Sachdeva, Sonny; Kuo, Mei-Chen; Ren, Hui; Lingutla, Anitha; Emery, Michael; Haugen, Gregory M; Yandrasits, Michael A; Sharma, Neeraj; Coggio, William D; Hamrock, Steven J; Frey, Matthew H

    2012-05-20

    Original research was carried out at the CSM and the 3M Company from March 2007 through September 2011. The research was aimed at developing new to the world proton electrolyte materials for use in hydrogen fuel cells, in particular with high proton conductivity under hot and dry conditions (>100mS/cm at 120°C and 50%RH). Broadly stated, the research at 3M and between 3M and CSM that led to new materials took place in two phases: In the first phase, hydrocarbon membranes that could be formed by photopolymerization of monomer mixtures were developed for the purpose of determining the technical feasibility of achieving the program's Go/No-Go decision conductivity target of >100mS/cm at 120°C and 50%RH. In the second phase, attempts were made to extend the achieved conductivity level to fluorinated material systems with the expectation that durability and stability would be improved (over the hydrocarbon material). Highlights included: Multiple lots of an HPA-immobilized photocurable terpolymer derived from di-vinyl-silicotungstic acid (85%), n-butyl acrylate, and hexanediol diacrylate were prepared at 3M and characterized at 3M to exhibit an initial conductivity of 107mS/cm at 120°C and 47%RH (PolyPOM85v) using a Bekktech LLC sample fixture and TestEquity oven. Later independent testing by Bekktech LLC, using a different preheating protocol, on the same material, yielded a conductivity value of approximately 20mS/cm at 120°C and 50%RH. The difference in measured values is likely to have been the result of an instability of properties for the material or a difference in the measurement method. A dispersed catalyst fuel cell was fabricated and tested using a 150¼m thick HPA-based photocurable membrane (above, PolyPOM75v), exhibiting a current density of greater than 300mA/cm2 at 0.5V (H2/Air 800/1800sccm 70°C/75%RH ambient outlet pressure). Multiple lots of a co-polymer based on poly-trifluorovinylether (TFVE) derived HPA were synthesized and fabricated into

  1. High-temperature membranes for H{sub 2}S and SO{sub 2} separations. Final report

    SciTech Connect

    Winnick, J.

    1995-01-01

    Electrochemical cells which separate H{sub 2}S and S0{sub 2} from hot gas streams have two important materials issues that limit their successful industrial application: (1) membranes and (2) electrodes. These were the focus of the present study. For the H{sub 2}S work, experimental analysis incorporated several membrane and electrode materials; densified zirconia provided the best matrices for entrainment of electrolytic species, ionic mobility, and a process-gas barricade hindering the capabilities of gas cross-over, alternate reactions. Electrode materials of lithiated Ni converted to NiO in-situ were successful in polishing applications; however H{sub 2}S levels >100 ppM converted the NiO cathode to a molten nickel sulfide necessitating the use of Co. Lithiated NiO for the anode material remained morphologically stable and conductive in all experimentation. High temperature electrochemical removal of H{sub 2}S from coal gasification streams has been shown on the bench scale level at the Georgia Institute of Technology utilizing the aforementioned materials. Experimental removals from 1000 ppM to 100 ppM H{sub 2}S and 100 ppM to 10 ppM H{sub 2}S proved over 90% removal with applied current was economically feasible due to high current efficiencies ({approximately}100%) and low polarizations. For the S0{sub 2}work, an extensive search was conducted for a suitable membrane material for use in the S0{sub 2} removal system. The most favorable material found was Si{sub 3}N{sub 4}, proven to be more efficient than other possible materials. New lithiated NiO electrodes were also developed and characterized, proving more stable than previously used pervoskite electrodes. The combination of these new components led to 90% removal at near 100% current efficiency over a wide range of current densities.

  2. The Investigation and Development of Low Cost Hardware Components for Proton-Exchange Membrane Fuel Cells - Final Report

    SciTech Connect

    George A. Marchetti

    1999-12-15

    Proton exchange membrane (PEM) fuel cell components, which would have a low-cost structure in mass production, were fabricated and tested. A fuel cell electrode structure, comprising a thin layer of graphite (50 microns) and a front-loaded platinum catalyst layer (600 angstroms), was shown to produce significant power densities. In addition, a PEM bipolar plate, comprising flexible graphite, carbon cloth flow-fields and an integrated polymer gasket, was fabricated. Power densities of a two-cell unit using this inexpensive bipolar plate architecture were shown to be comparable to state-of-the-art bipolar plates.

  3. NASA In-step: Permeable Membrane Experiment

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Viewgraphs on the Permeable Membrane Experiment are presented. An experiment overview is given. The Membrane Phase Separation Experiment, Membrane Diffusion Interference Experiment, and Membrane Wetting Experiment are described. Finally, summary and conclusions are discussed.

  4. Development of a membrane-based process for the treatment of oily waste waters. Final report, March 4, 1992--March 5, 1994

    SciTech Connect

    McCray, S.B.

    1994-05-25

    This is a final report from Bend Research, Inc., (BRI) to the U.S. Department of Energy (DOE) for work performed under Contract No. DE-AC22-92MT92005, titled {open_quotes}Development of a Membrane-Based Process for the Treatment of Oily Waste Waters.{close_quotes} This report covers the period from March 4, 1992, to March 5, 1994. The overall goal of this program was to develop an economical oily-water treatment system based on reverse osmosis (RO). The RO system would be used to (1) reduce oil production costs by reducing the volume of waste water that must be disposed of, (2) form the basis of a generic waste-water treatment system that can easily be integrated into oil-field operations, especially at production facilities that are small or in remote locations; and (3) produce water clean enough to meet existing and anticipated environmental regulations. The specific focus of this program was the development of a hollow-fiber membrane module capable of treating oily waste waters.

  5. Research and development of proton-exchange membrane (PEM) fuel cell system for transportation applications. Phase I final report

    SciTech Connect

    1996-01-01

    Objective during Phase I was to develop a methanol-fueled 10-kW fuel cell power source and evaluate its feasibility for transportation applications. This report documents research on component (fuel cell stack, fuel processor, power source ancillaries and system sensors) development and the 10-kW power source system integration and test. The conceptual design study for a PEM fuel cell powered vehicle was documented in an earlier report (DOE/CH/10435-01) and is summarized herein. Major achievements in the program include development of advanced membrane and thin-film low Pt-loaded electrode assemblies that in reference cell testing with reformate-air reactants yielded performance exceeding the program target (0.7 V at 1000 amps/ft{sup 2}); identification of oxidation catalysts and operating conditions that routinely result in very low CO levels ({le} 10 ppm) in the fuel processor reformate, thus avoiding degradation of the fuel cell stack performance; and successful integrated operation of a 10-kW fuel cell stack on reformate from the fuel processor.

  6. Final Report of a CRADA Between Pacific Northwest National Laboratory and the General Motors Company (CRADA No. PNNL/271): “Degradation Mechanisms of Urea Selective Catalytic Reduction Technology”

    SciTech Connect

    Kim, Do Heui; Lee, Jong H.; Peden, Charles HF; Howden, Ken; Kim, Chang H.; Oh, Se H.; Schmieg, Steven J.; Wiebenga, Michelle H.

    2011-12-13

    Diesel engines can offer substantially higher fuel efficiency, good driving performance characteristics, and reduced carbon dioxide (CO2) emission compared to stoichiometric gasoline engines. Despite the increasing public demand for higher fuel economy and reduced dependency on imported oil, however, meeting the stringent emission standards with affordable methods has been a major challenge for the wide application of these fuel-efficient engines in the US market. The selective catalytic reduction of NOx by urea (urea-SCR) is one of the most promising technologies for NOx emission control for diesel engine exhausts. To ensure successful NOx emission control in the urea-SCR technology, both a diesel oxidation catalyst (DOC) and a urea-SCR catalyst with high activity and durability are critical for the emission control system. Because the use of this technology for light-duty diesel vehicle applications is new, the relative lack of experience makes it especially challenging to satisfy the durability requirements. Of particular concern is being able to realistically simulate actual field aging of the catalyst systems under laboratory conditions, which is necessary both as a rapid assessment tool for verifying improved performance and certifiability of new catalyst formulations. In addition, it is imperative to develop a good understanding of deactivation mechanisms to help develop improved catalyst materials. In this CRADA program, General Motors Company and PNNL have investigated fresh, laboratory- and vehicle-aged DOC and SCR catalysts. The studies have led to a better understanding of various aging factors that impact the long-term performance of catalysts used in the urea-SCR technology, and have improved the correlation between laboratory and vehicle aging for reduced development time and cost. This Final Report briefly highlights many of the technical accomplishments and documents the productivity of the program in terms of peer-reviewed scientific publications

  7. 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

  8. Examination of Bacterial Inhibition Using a Catalytic DNA

    PubMed Central

    Qu, Long; Ali, M. Monsur; Aguirre, Sergio D.; Liu, Hongxia; Jiang, Yuyang; Li, Yingfu

    2014-01-01

    Determination of accurate dosage of existing antibiotics and discovery of new antimicrobials or probiotics entail simple but effective methods that can conveniently track bacteria growth and inhibition. Here we explore the application of a previously reported fluorogenic E. coli-specific DNAzyme (catalytic DNA), RFD-EC1, as a molecular probe for monitoring bacterial inhibition exerted by antibiotics and for studying bacterial competition as a result of cohabitation. Because the DNAzyme method provides a convenient way to monitor the growth of E. coli, it is capable of determining the minimal inhibitory concentration (MIC) of antibiotics much faster than the conventional optical density (OD) method. In addition, since the target for RFD-EC1 is an extracellular protein molecule from E. coli, RFD-EC1 is able to identify pore-forming antibiotics or compounds that can cause membrane leakage. Finally, RFD-EC1 can be used to analyse the competition of cohabitating bacteria, specifically the inhibition of growth of E. coli by Bacillus subtilis. The current work represents the first exploration of a catalytic DNA for microbiological applications and showcases the utility of bacteria-sensing fluorogenic DNAzymes as simple molecular probes to facilitate antibiotic and probiotic research. PMID:25531274

  9. Examination of bacterial inhibition using a catalytic DNA.

    PubMed

    Qu, Long; Ali, M Monsur; Aguirre, Sergio D; Liu, Hongxia; Jiang, Yuyang; Li, Yingfu

    2014-01-01

    Determination of accurate dosage of existing antibiotics and discovery of new antimicrobials or probiotics entail simple but effective methods that can conveniently track bacteria growth and inhibition. Here we explore the application of a previously reported fluorogenic E. coli-specific DNAzyme (catalytic DNA), RFD-EC1, as a molecular probe for monitoring bacterial inhibition exerted by antibiotics and for studying bacterial competition as a result of cohabitation. Because the DNAzyme method provides a convenient way to monitor the growth of E. coli, it is capable of determining the minimal inhibitory concentration (MIC) of antibiotics much faster than the conventional optical density (OD) method. In addition, since the target for RFD-EC1 is an extracellular protein molecule from E. coli, RFD-EC1 is able to identify pore-forming antibiotics or compounds that can cause membrane leakage. Finally, RFD-EC1 can be used to analyse the competition of cohabitating bacteria, specifically the inhibition of growth of E. coli by Bacillus subtilis. The current work represents the first exploration of a catalytic DNA for microbiological applications and showcases the utility of bacteria-sensing fluorogenic DNAzymes as simple molecular probes to facilitate antibiotic and probiotic research. PMID:25531274

  10. 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.

  11. Nanomaterial-enabled membranes for water treatment

    NASA Astrophysics Data System (ADS)

    Rogensues, Adam Roy

    Incorporating engineered nanomaterials as components of synthetic membranes can improve their separation performance and endow membranes with additional functions. This work explores two approaches to the design of membranes modified with nanomaterials. In the first chapter, exfoliated graphite nanoplatelets (xGnP) decorated with gold nanoparticles were embedded in a polysulfone matrix to fabricate phase inversion nanocomposite membranes. The cast membranes were evaluated as flow-through membrane reactors in experiments on the catalytic reduction of 4-nitrophenol. The nanocomposite membranes were not as catalytically efficient as those fabricated by modifying anodized alumina membranes polyelectrolyte multilayers (PEMs) containing gold nanoparticles. However, because of the facility of membrane casting by phase inversion and new opportunities enabled by the demonstrated hierarchy-based approach to nanocomposite membrane design, such membrane may hold commercial promise. In the second part of the study, the practicability of PEM-based nanofiltration was evaluated under conditions of precipitative fouling (i.e. scaling) by calcium sulfate. Polyelectrolytes were deposited onto 50 kDa polyethersulfone membranes to create PEM-based nanofiltration membranes. The prepared membranes were compared with the commercial NF270 membrane in terms of flux and rejection performance, as well as the morphology of gypsum crystals formed on the membrane surface. None of the PEM coatings tested inhibited scale formation.

  12. 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.

  13. 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.

  14. Functional nanofibers and membranes by electrospinning

    NASA Astrophysics Data System (ADS)

    Formo, Eric Victor

    This research focuses on advances in the fabrication of functional membranes through the process of electrospinning to either alter the arrangement or composition of nanofiber arrays. To control nanofiber arrangement, easily reconfigurable collectors were constructed that could direct the deposition over large areas (>50 cm2) and pattern the membranes into various designs, including parallel, fan-out, and spiral arrays. Subsequently, the composition of electrospun membranes was modified using the sol-gel method to yield fibers composed of TiO2 (anatase and rutile) and ZrO 2 (tetragonal) phases. Implementing the polyol reduction method, these nanofiber surfaces were coated with Pt, Pd, and Rh nanoparticles of 2-5 nm or Pt nanowires with lengths up to 125 nm. Interestingly, by calcining the ZrO2 at a lower temperature, the nanofibers could mediate the growth of Pt nanostars or Pt nanowires by adjusting the Pt precursor concentration in the polyol reduction bath. The anatase membranes could also be modified through the self-assembly of various silanes to give either thiol or amine surface groups. The functionalized membranes were then tested for a number of applications associated with the catalysis field. Specifically, anatase fiber membranes coated with Pt and Pd nanoparticles were used as catalysts in a continuous flow reactor for either hydrogenation or cross-coupling reactions, respectively, which was proven to operate with a high yield, a rapid flow rate, and were readily recyclable. The effects of both the coverage and morphology of the Pt-decorated anatase fibers on the methanol oxidation reaction were then studied. Nanofibers with a submonolayer of Pt nanoparticles or Pt nanowires were found to display improved catalytic durability over commercial Pt/C as determined by chronoamperometry. Further, by utilizing the oxygen reduction reaction, results showed that the Pt nanostars had superior electrochemical properties in comparison to Pt black. Finally, the

  15. Novel selective surface flow (SSF{trademark}) membranes for the recovery of hydrogen from waste gas streams. Phase 2: Technology development, final report

    SciTech Connect

    Anand, M.; Ludwig, K.A.

    1996-04-01

    The objective of Phase II of the Selective Surface Flow Membrane program was Technology Development. Issues addressed were: (i) to develop detailed performance characteristics on a 1 ft{sup 2} multi- tube module and develop design data, (ii) to build a field test rig and complete field evaluation with the 1 ft{sup 2} area membrane system, (iii) to implement membrane preparation technology and demonstrate membrane performance in 3.5 ft long tube, (iv) to complete detailed process design and economic analysis.

  16. Efficient process for previous metal recovery from cell membrane electrode assemblies

    DOEpatents

    Shore, Lawrence; Matlin, Ramail; Heinz, Robert

    2010-05-04

    A method is provided for recovering a catalytic element from a fuel cell membrane electrode assembly. The method includes grinding the membrane electrode assembly into a powder, extracting the catalytic element by forming a slurry comprising the powder and an acid leachate adapted to dissolve the catalytic element into a soluble salt, and separating the slurry into a depleted powder and a supernatant containing the catalytic element salt. The depleted powder is washed to remove any catalytic element salt retained within pores in the depleted powder and the catalytic element is purified from the salt.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Component Development to Accelerate Commercial Implementation of Ultra-Low Emissions Catalytic Combustion

    SciTech Connect

    McCarty, Jon; Berry, Brian; Lundberg, Kare; Anson, Orris

    2003-03-31

    This final report describes a 2000-2003 program for the development of components and processes to enhance the commercialization of ultra-low emissions catalytic combustion in industrial gas turbines. The range of project tasks includes: development of more durable, lower-cost catalysts and catalytic combustor components; development and design of a catalytic pre-burner and a catalytic pilot burner for gas turbines, and on-site fuel conversion processing for utilization of liquid fuel.

  2. 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.

  3. Reactor vessel using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.; Zeltner, Walter A.

    1992-08-11

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane.

  4. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    In this project we well evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated. (VC)

  5. 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.

  6. Viral membrane fusion

    PubMed Central

    Harrison, Stephen C.

    2015-01-01

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. PMID:25866377

  7. Membrane treatment of Aqueous Film Forming Foam (AFFF) wastes for recovery of its active ingredients. Final report, Mar 79-Sep 80

    SciTech Connect

    Chian, E.S.K.; Wu, T.P.; Rowland, R.W.

    1980-10-01

    Ultrafiltration (UF) and Reverse Osmosis (RO) treatment of Aqueous Film Forming Foam (AFFF) solutions was investigated to determine the feasibility of employing membrane processes to separate and recover AFFF active ingredients for reuse. Studies were performed on both 6% AFFF in tap-water solutions and on actual wastewaters spiked with 3% or 6% AFFF. The AFFF materials used in this study consisted of Ansul, 3M FC-206, and 3M FC-780. Membrane employed for these studies included Abcor HFD, HFF, HFJ, and HFK tubular ultrafiltration (UF) membranes and a DuPont B-10 reverse osmosis (RO) module. Parameters monitored to represent AFFF ingredients were TOC, dissolved solids, surfactants, and % glycol. An attempt was also made to determine fluorocarbons as fluoride. Membrane fluxes were also determined. Results of this study demonstrate the feasibility of employing UF-RO processes to separate and recover the AFFF active ingredients for reuse. Approximately 75% recovery of the AFFF active ingredients as represented by the foam test was attained. An economic analysis of the membrane treatment processes indicates that it is extremely favorable in recovering the AFFF wastewater for reuse. Pilot-scale studies are, however, necessary to fully establish the process feasibilities and economics of the AFFF recovery system.

  8. 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.

  9. 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.

  10. 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.

  11. A new integrated approach for dye removal from wastewater by polyoxometalates functionalized membranes.

    PubMed

    Yao, Lei; Zhang, Lizhi; Wang, Rong; Chou, Shuren; Dong, ZhiLi

    2016-01-15

    Membrane technique is a promising way for the removal of dyes from wastewater. A unique approach combining both the adsorptive and the catalytic membrane processes was proposed on the basis of a new functionalized membrane. The membrane integrating both the adsorptive and catalytic activities was developed by introducing polyoxometalates (POMs) as an ideal candidate for the membrane functionalization via a novel sol-gel method. A two-step protocol, adsorptive separation and catalytic degradation, was designed for dye removal, realizing an excellent dye rejection with easy and economic membrane regeneration through simply soaking the membrane in a limited volume of dilute oxidant solution. This approach is feasible and versatile owing to the flexible selection of distinct POMs and design of catalytic degradation routes as required. As a result, the current research provides insight into a new methodology of the membrane technique in dye removal applications. PMID:26410275

  12. Architecture and function of metallopeptidase catalytic domains

    PubMed Central

    Cerdà-Costa, Núria; Gomis-Rüth, Francesc Xavier

    2014-01-01

    The cleavage of peptide bonds by metallopeptidases (MPs) is essential for life. These ubiquitous enzymes participate in all major physiological processes, and so their deregulation leads to diseases ranging from cancer and metastasis, inflammation, and microbial infection to neurological insults and cardiovascular disorders. MPs cleave their substrates without a covalent intermediate in a single-step reaction involving a solvent molecule, a general base/acid, and a mono-or dinuclear catalytic metal site. Most monometallic MPs comprise a short metal-binding motif (HEXXH), which includes two metal-binding histidines and a general base/acid glutamate, and they are grouped into the zincin tribe of MPs. The latter divides mainly into the gluzincin and metzincin clans. Metzincins consist of globular ∼130–270-residue catalytic domains, which are usually preceded by N-terminal pro-segments, typically required for folding and latency maintenance. The catalytic domains are often followed by C-terminal domains for substrate recognition and other protein–protein interactions, anchoring to membranes, oligomerization, and compartmentalization. Metzincin catalytic domains consist of a structurally conserved N-terminal subdomain spanning a five-stranded β-sheet, a backing helix, and an active-site helix. The latter contains most of the metal-binding motif, which is here characteristically extended to HEXXHXXGXX(H,D). Downstream C-terminal subdomains are generally shorter, differ more among metzincins, and mainly share a conserved loop—the Met-turn—and a C-terminal helix. The accumulated structural data from more than 300 deposited structures of the 12 currently characterized metzincin families reviewed here provide detailed knowledge of the molecular features of their catalytic domains, help in our understanding of their working mechanisms, and form the basis for the design of novel drugs. PMID:24596965

  13. Membrane stabilizer

    DOEpatents

    Mingenbach, William A.

    1988-01-01

    A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material.

  14. Transport in a Microfluidic Catalytic Reactor

    SciTech Connect

    Park, H G; Chung, J; Grigoropoulos, C P; Greif, R; Havstad, M; Morse, J D

    2003-04-30

    A study of the heat and mass transfer, flow, and thermodynamics of the reacting flow in a catalytic microreactor is presented. Methanol reforming is utilized in the fuel processing system driving a micro-scale proton exchange membrane fuel cell. Understanding the flow and thermal transport phenomena as well as the reaction mechanisms is essential for improving the efficiency of the reforming process as well as the quality of the processed fuel. Numerical studies have been carried out to characterize the transport in a silicon microfabricated reactor system. On the basis of these results, optimized conditions for fuel processing are determined.

  15. Possible involvement of membrane lipids peroxidation and oxidation of catalytically essential thiols of the cerebral transmembrane sodium pump as component mechanisms of iron-mediated oxidative stress-linked dysfunction of the pump's activity

    PubMed Central

    Omotayo, T.I.; Akinyemi, G.S.; Omololu, P.A.; Ajayi, B.O.; Akindahunsi, A.A.; Rocha, J.B.T.; Kade, I.J.

    2014-01-01

    The precise molecular events defining the complex role of oxidative stress in the inactivation of the cerebral sodium pump in radical-induced neurodegenerative diseases is yet to be fully clarified and thus still open. Herein we investigated the modulation of the activity of the cerebral transmembrane electrogenic enzyme in Fe2+-mediated in vitro oxidative stress model. The results show that Fe2+ inhibited the transmembrane enzyme in a concentration dependent manner and this effect was accompanied by a biphasic generation of aldehydic product of lipid peroxidation. While dithiothreitol prevented both Fe2+ inhibitory effect on the pump and lipid peroxidation, vitamin E prevented only lipid peroxidation but not inhibition of the pump. Besides, malondialdehyde (MDA) inhibited the pump by a mechanism not related to oxidation of its critical thiols. Apparently, the low activity of the pump in degenerative diseases mediated by Fe2+ may involve complex multi-component mechanisms which may partly involve an initial oxidation of the critical thiols of the enzyme directly mediated by Fe2+ and during severe progression of such diseases; aldehydic products of lipid peroxidation such as MDA may further exacerbate this inhibitory effect by a mechanism that is likely not related to the oxidation of the catalytically essential thiols of the ouabain-sensitive cerebral electrogenic pump. PMID:25618580

  16. Possible involvement of membrane lipids peroxidation and oxidation of catalytically essential thiols of the cerebral transmembrane sodium pump as component mechanisms of iron-mediated oxidative stress-linked dysfunction of the pump's activity.

    PubMed

    Omotayo, T I; Akinyemi, G S; Omololu, P A; Ajayi, B O; Akindahunsi, A A; Rocha, J B T; Kade, I J

    2015-01-01

    The precise molecular events defining the complex role of oxidative stress in the inactivation of the cerebral sodium pump in radical-induced neurodegenerative diseases is yet to be fully clarified and thus still open. Herein we investigated the modulation of the activity of the cerebral transmembrane electrogenic enzyme in Fe(2+)-mediated in vitro oxidative stress model. The results show that Fe(2+) inhibited the transmembrane enzyme in a concentration dependent manner and this effect was accompanied by a biphasic generation of aldehydic product of lipid peroxidation. While dithiothreitol prevented both Fe(2+) inhibitory effect on the pump and lipid peroxidation, vitamin E prevented only lipid peroxidation but not inhibition of the pump. Besides, malondialdehyde (MDA) inhibited the pump by a mechanism not related to oxidation of its critical thiols. Apparently, the low activity of the pump in degenerative diseases mediated by Fe(2+) may involve complex multi-component mechanisms which may partly involve an initial oxidation of the critical thiols of the enzyme directly mediated by Fe(2+) and during severe progression of such diseases; aldehydic products of lipid peroxidation such as MDA may further exacerbate this inhibitory effect by a mechanism that is likely not related to the oxidation of the catalytically essential thiols of the ouabain-sensitive cerebral electrogenic pump. PMID:25618580

  17. 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.

  18. 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.

  19. 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.

  20. Design and development of a self-regenerative contained-liquid membrane process for combined SO{sub x} and NO{sub x} removal. Final report

    SciTech Connect

    Varanasi, S.; LeBlanc, S.E.

    1992-11-01

    The lack of an efficient, cost effective process for the removal of sulfur compounds from gas streams (either gasified coal or flue gases resulting from coal combustion) is a major obstacle to the economic utilization of high sulfur Ohio coal. The most economically favorable processes for the desulfurization of flue gases are the regenerable processes as opposed to the `throwaway` processes. In addition, recovery of sulfur from these gases in the form of elemental sulfur or H{sub 2}SO{sub 4} does seem to be an essential step in the economic utilization of high sulfur coal. n light of these observations, a recently proposed FGD process which regenerates the scrubbing liquor ``in-situ`` as well as recovering a concentrated S0{sub 2} stream for use in sulfuric acid production, is quite promising. Conventional processes, presently in operation, employ large packed tower scrubbers for S0{sub 2} absorption which results in very high capital expenditures and operating costs. Recent developments in membrane technology can now provide us with an alternative to these large packed towers for stack gas cleanup. In this research we have investigated the use of novel membrane contactors for replacing more conventional packed absorbers. Contained-liquid membranes, exploiting carrier mediated transpose, enable the scrubbing liquid to be regenerated ``in-site,`` in a single process unit. Microporous single-ply polymeric membranes have recently been used in gas-liquid and liquid-liquid contactors. These membranes are fashioned into a tubular shape (i.e. long, thin fibers) for use in mass transfer contactors.

  1. Viral membrane fusion

    SciTech Connect

    Harrison, Stephen C.

    2015-05-15

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. - Highlights: • Viral fusion proteins overcome the high energy barrier to lipid bilayer merger. • Different molecular structures but the same catalytic mechanism. • Review describes properties of three known fusion-protein structural classes. • Single-virion fusion experiments elucidate mechanism.

  2. 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

  3. 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

  4. Cellulosic Biomass Sugars to Advantage Jet Fuel: Catalytic Conversion of Corn Stover to Energy Dense, Low Freeze Point Paraffins and Naphthenes: Cooperative Research and Development Final Report, CRADA Number CRD-12-462

    SciTech Connect

    Elander, Rick

    2015-08-04

    NREL will provide scientific and engineering support to Virent Energy Systems in three technical areas: Process Development/Biomass Deconstruction; Catalyst Fundamentals; and Technoeconomic Analysis. The overarching objective of this project is to develop the first fully integrated process that can convert a lignocellulosic feedstock (e.g., corn stover) efficiently and cost effectively to a mix of hydrocarbons ideally suited for blending into jet fuel. The proposed project will investigate the integration of Virent Energy System’s novel aqueous phase reforming (APR) catalytic conversion technology (BioForming®) with deconstruction technologies being investigated by NREL at the 1-500L scale. Corn stover was chosen as a representative large volume, sustainable feedstock.

  5. 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

  6. 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.

  7. 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.

  8. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 1 - effects of solvents, catalysts and temperature conditions on conversion and structural changes of low-rank coals

    SciTech Connect

    Lili Huang; Schobert, H.H.; Chunshan Song

    1998-01-01

    The main objectives of this project were to study the effects of low-temperature pretreatments on coal structure and their impacts on subsequent liquefaction. The effects of pretreatment temperatures, catalyst type, coal rank, and influence of solvent were examined. Specific objectives were to identify the basic changes in coal structure induced by catalytic and thermal pretreatments, and to determine the reactivity of the catalytically and thermally treated coals for liquefaction. In the original project management plan it was indicated that six coals would be used for the study. These were to include two each of bituminous, subbituminous, and lignite rank. For convenience in executing the experimental work, two parallel efforts were conducted. The first involved the two lignites and one subbituminous coal; and the second, the two bituminous coals and the remaining subbituminous coal. This Volume presents the results of the first portion of the work, studies on two lignites and one subbituminous coal. The remaining work accomplished under this project will be described and discussed in Volume 2 of this report. The objective of this portion of the project was to determine and compare the effects of solvents, catalysts and reaction conditions on coal liquefaction. Specifically, the improvements of reaction conversion, product distribution, as well as the structural changes in the coals and coal-derived products were examined. This study targeted at promoting hydrogenation of the coal-derived radicals, generated during thermal cleavage of chemical bonds, by using a good hydrogen donor-solvent and an effective catalyst. Attempts were also made in efforts to match the formation and hydrogenation of the free radicals and thus to prevent retrogressive reaction.

  9. 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.

  10. 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.

  11. The use of ozonation and catalytic ozonation combined with ultrafiltration for the control of natural organic matter (NOM) and disinfection by-products (DBPs) in drinking water

    NASA Astrophysics Data System (ADS)

    Karnik, Bhavana Sushilkumar

    Commercially available titania membranes, with a molecular weight cut-off of 15, 5, 1 kD were used in a ozonation/membrane system that was fed with water from Lake Lansing. The effects of ozonation on permeate flux recovery and membrane fouling was investigated. In addition the effects of ozonation/membrane filtration hybrid process on the removal of the natural organic matter (NOM) and the formation of disinfection by-products (DBPS) were monitored. The commercial membrane (CeRAM Inside, Tami North America, St. Laurent, Quebec, Canada) was coated with iron oxide nanoparticles (4--6 nm in diameter) using a layer-by-layer technique and sintered in air for 30 minutes. Surface characterization was carried out using electron microscopy techniques and atomic force microscopy, to study the changes in structure and surface morphology of the membranes. The removal and survival of bacteria in the process was also evaluated using fluorescence microscopy and microbial assays. Finally the surface catalytic reaction was investigated to propose the mechanism responsible for the improved performance of the hybrid process. The permeate flux through a titania coated ceramic membrane was significantly affected by ozonation. A minimum threshold ozone concentration (2.5 g/m 3) could achieve complete recovery of permeate flux after fouling. Ozonation/filtration decreased the concentration of chlorinated disinfection by-products up to 80%. With catalyst coated membranes, the concentration of dissolved organic carbon was reduced by >85% and the concentrations of disinfection by-products decreased by up to 90%. Furthermore with the coated membrane, the concentrations of ozonation by-products in the permeate were reduced by >50% as compared to that obtained with the uncoated membranes, thus reducing the risk of potential regrowth of bacteria in the distribution system. Application of the hybrid process lead to greater than 7 log removal of bacteria. Surface characterization showed that

  12. Catalytic oxidation for treatment of ECLSS and PMMS waste streams

    NASA Technical Reports Server (NTRS)

    Akse, James R.; Jolly, Clifford D.

    1991-01-01

    It is shown that catalytic oxidation is an effective technique for the removal of trace organic contaminants in a multifiltration potable processor's effluent. Essential elements of this technology are devices that deliver oxygen to the influent, and remove gaseous reaction byproducts from the effluent, via hollow-tube, gas-permeable membranes. Iodine, which poisons existing catalysis, is removed by a small deiodination bed prior to catalytic reactor entrance. The catalyst used is a mixture of Pt and Ru deposited on carbon, operating at 125-160 C and 39-90 psi pressures.

  13. Polyethersulfone hollow fiber modified with poly(styrenesulfonate) and Pd nanoparticles for catalytic reaction

    NASA Astrophysics Data System (ADS)

    Emin, C.; Gu, Y.; Remigy, J.-C.; Lahitte, J.-F.

    2015-07-01

    The aim of this work is the synthesis of polymer-stabilized Pd nanoparticles (PdNP) inside a functionalized polymeric porous membrane in order to develop hybrid catalytic membrane reactors and to test them in model metal-catalyzed organic reactions. For this goal, a polymeric membrane support (Polyethersulfone hollow fiber-shaped) was firstly functionalized with an ionogenic polymer (i.e. poly(styrenesulfonate) capable to retain PdNP precursors using an UV photo-grafting method. PdNP were then generated inside the polymeric matrix by chemical reduction of precursor salts (intermatrix synthesis). The catalytic performance of the PdNP catalytic membranes was evaluated using reduction of nitrophenol by sodium borohydride (NaBH4) in water.

  14. Membrane stabilizer

    DOEpatents

    Mingenbach, W.A.

    1988-02-09

    A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material. 10 figs.

  15. Final report on LDRD project : elucidating performance of proton-exchange-membrane fuel cells via computational modeling with experimental discovery and validation.

    SciTech Connect

    Wang, Chao Yang (Pennsylvania State University, University Park, PA); Pasaogullari, Ugur (Pennsylvania State University, University Park, PA); Noble, David R.; Siegel, Nathan P.; Hickner, Michael A.; Chen, Ken Shuang

    2006-11-01

    In this report, we document the accomplishments in our Laboratory Directed Research and Development project in which we employed a technical approach of combining experiments with computational modeling and analyses to elucidate the performance of hydrogen-fed proton exchange membrane fuel cells (PEMFCs). In the first part of this report, we document our focused efforts on understanding water transport in and removal from a hydrogen-fed PEMFC. Using a transparent cell, we directly visualized the evolution and growth of liquid-water droplets at the gas diffusion layer (GDL)/gas flow channel (GFC) interface. We further carried out a detailed experimental study to observe, via direct visualization, the formation, growth, and instability of water droplets at the GDL/GFC interface using a specially-designed apparatus, which simulates the cathode operation of a PEMFC. We developed a simplified model, based on our experimental observation and data, for predicting the onset of water-droplet instability at the GDL/GFC interface. Using a state-of-the-art neutron imaging instrument available at NIST (National Institute of Standard and Technology), we probed liquid-water distribution inside an operating PEMFC under a variety of operating conditions and investigated effects of evaporation due to local heating by waste heat on water removal. Moreover, we developed computational models for analyzing the effects of micro-porous layer on net water transport across the membrane and GDL anisotropy on the temperature and water distributions in the cathode of a PEMFC. We further developed a two-phase model based on the multiphase mixture formulation for predicting the liquid saturation, pressure drop, and flow maldistribution across the PEMFC cathode channels. In the second part of this report, we document our efforts on modeling the electrochemical performance of PEMFCs. We developed a constitutive model for predicting proton conductivity in polymer electrolyte membranes and compared

  16. Final technical report. A sodium-cycle based organism with improved membrane resistance aimed at increasing the efficiency of energy biotransformations

    SciTech Connect

    Lewis, Kim

    2001-06-01

    The aim of the project was to express in E. coli components that would allow a formation of oxidative phosphorylation based on a sodium cycle. This would improve the resistance of cells to organic solvents, detergents and other toxins. The author cloned and expressed the nqr operon from H. influenzae in E. coli. Experiments with membrane vesicles indicated the presence of the functional recombinant sodium pumping NADH dehydrogenase. A gene for a hybrid E. coli/P.modestum ATPase was constructed which will enable one to co-express a sodium ATPsynthase together with a sodium NADH dehydrogenase.

  17. 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.

  18. [Studies on photo-electron-chemical catalytic degradation of the malachite green].

    PubMed

    Li, Ming-yu; Diao, Zeng-hui; Song, Lin; Wang, Xin-le; Zhang, Yuan-ming

    2010-07-01

    A novel two-compartment photo-electro-chemical catalytic reactor was designed. The TiO2/Ti thin film electrode thermally formed was used as photo-anode, and graphite as cathode and a saturated calomel electrode (SCE) as the reference electrode in the reactor. The anode compartment and cathode compartment were connected with the ionic exchange membrane in this reactor. Effects of initial pH, initial concentration of malachite green and connective modes between the anode compartment and cathode compartment on the decolorization efficiency of malachite green were investigated. The degradation dynamics of malachite green was studied. Based on the change of UV-visible light spectrum, the degradation process of malachite green was discussed. The experimental results showed that, during the time of 120 min, the decolouring ratio of the malachite green was 97.7% when initial concentration of malachite green is 30 mg x L(-1) and initial pH is 3.0. The catalytic degradation of malachite green was a pseudo-first order reaction. In the degradation process of malachite green the azo bond cleavage and the conjugated system of malachite green were attacked by hydroxyl radical. Simultaneity, the aromatic ring was oxidized. Finally, malachite green was degraded into other small molecular compounds. PMID:20825023

  19. 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.

  20. 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.

  1. Innovative Clean Coal Technology (ICCT). Demonstration of Selective Catalytic Reduction (SCR) technology for the control of nitrogen oxide (NO{sub x}) emissions from high-sulfur coal-fired boilers: Volume 3, Appendices O--T. Final report

    SciTech Connect

    1996-10-01

    Volume 3 contains the following appendices: Appendix O, Second Series-Manual APH Tests; Appendix P, Third Series-Manual APH Tests; Appendix Q, ABB Analysis of Air Preheaters-Final Report; Appendix R, ABB Corrosion Analysis Study; Appendix S, SRI Waste Stream Impacts Study; and Appendix T, Economic Evaluation.

  2. Membrane tension and membrane fusion.

    PubMed

    Kozlov, Michael M; Chernomordik, Leonid V

    2015-08-01

    Diverse cell biological processes that involve shaping and remodeling of cell membranes are regulated by membrane lateral tension. Here we focus on the role of tension in driving membrane fusion. We discuss the physics of membrane tension, forces that can generate the tension in plasma membrane of a cell, and the hypothesis that tension powers expansion of membrane fusion pores in late stages of cell-to-cell and exocytotic fusion. We propose that fusion pore expansion can require unusually large membrane tensions or, alternatively, low line tensions of the pore resulting from accumulation in the pore rim of membrane-bending proteins. Increase of the inter-membrane distance facilitates the reaction. PMID:26282924

  3. 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.

  4. Innovative Clean Coal Technology (ICCT): Demonstration of selective catalytic reduction technology for the control of nitrogen oxide emissions from high-sulfur coal-fired boilers. First and second quarterly technical progress reports, [January--June 1995]. Final report

    SciTech Connect

    1995-12-31

    The objective of this project is to demonstrate and evaluate commercially available Selective Catalytic Reduction (SCR) catalysts from US, Japanese and European catalyst suppliers on a high-sulfur US coal-fired boiler. SCR is a post-combustion nitrogen oxide (NO{sub x}) control technology that involves injecting ammonia (NH{sub 3}) into the flue gas generated from coal combustion in an electric utility boiler. The flue gas containing ammonia is then passed through a reactor containing a specialized catalyst. In the presence of the catalyst, the ammonia reacts with NO{sub x} to convert it to nitrogen and water vapor. Although SCR is widely practiced in Japan and Europe on gas-, oil-, and low-sulfur coal-fired boilers, there are several technical uncertainties associated with applying SCR to US coals. These uncertainties include: (1) potential catalyst deactivation due to poisoning by trace metal species present in US coals that are not present in other fuels. (2) performance of the technology and effects on the balance-of-plant equipment in the presence of high amounts of SO{sub 2} and SO{sub 3}. (3) performance of a wide variety of SCR catalyst compositions, geometries, and methods of manufacture under typical high-sulfur coal-fired utility operating conditions. These uncertainties are being explored by operating a series of small-scale SCR reactors and simultaneously exposing different SCR catalysts to flue gas derived from the combustion of high sulfur US coal. The demonstration is being performed at Gulf Power Company`s Plant Crist Unit No. 5 (75 MW nameplate capacity) near Pensacola, Florida. The project is funded by the US Department of Energy (DOE), Southern Company Services, Inc. (SCS on behalf of the entire Southern electric system), the Electric Power Research Institute (EPRI), and Ontario Hydro. SCS is the participant responsible for managing all aspects of this project.

  5. Innovative Clean Coal Technology (ICCT). Demonstration of Selective Catalytic Reduction (SCR) technology for the control of nitrogen oxide (NO{sub x}) emissions from high-sulfur coal-fired boilers: Volume 1. Final report

    SciTech Connect

    1996-10-01

    The objective of this project is to demonstrate and evaluate commercially available Selective Catalytic Reduction (SCR) catalysts from U.S., Japanese and European catalyst suppliers on a high-sulfur U.S. coal-fired boiler. SCR is a post-combustion nitrogen oxide (NO.) control technology that involves injecting ammonia into the flue gas generated from coal combustion in an electric utility boiler. The flue gas containing ammonia is then passed through a reactor that contains a specialized catalyst. In the presence of the catalyst, the ammonia reacts with NO. to convert it to nitrogen and water vapor. Although SCR is widely practiced in Japan and Europe on gas-, oil-, and low-sulfur coal- fired boilers, there are several technical uncertainties associated with applying SCR to U.S. coals. These uncertainties include: 1) potential catalyst deactivation due to poisoning by trace metal species present in U.S. coals that are not present in other fuels. 2) performance of the technology and effects on the balance-of- plant equipment in the presence of high amounts of SO{sub 2} and SO{sub 3}. 3) performance of a wide variety of SCR catalyst compositions, geometries and methods of manufacturer under typical high-sulfur coal-fired utility operating conditions. These uncertainties were explored by operating nine small-scale SCR reactors and simultaneously exposing different SCR catalysts to flue gas derived from the combustion of high sulfur U.S. coal. In addition, the test facility operating experience provided a basis for an economic study investigating the implementation of SCR technology.

  6. Membrane tethering

    PubMed Central

    Chia, Pei Zhi Cheryl

    2014-01-01

    Membrane trafficking depends on transport vesicles and carriers docking and fusing with the target organelle for the delivery of cargo. Membrane tethers and small guanosine triphosphatases (GTPases) mediate the docking of transport vesicles/carriers to enhance the efficiency of the subsequent SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)-mediated fusion event with the target membrane bilayer. Different classes of membrane tethers and their specific intracellular location throughout the endomembrane system are now well defined. Recent biochemical and structural studies have led to a deeper understanding of the mechanism by which membrane tethers mediate docking of membrane carriers as well as an appreciation of the role of tethers in coordinating the correct SNARE complex and in regulating the organization of membrane compartments. This review will summarize the properties and roles of membrane tethers of both secretory and endocytic systems. PMID:25343031

  7. FINAL REPORT

    SciTech Connect

    Horn, Mark W; McDaniel, Anthony; Schweighardt, Frank K

    2003-05-23

    In this program the teams at Penn State University (PSU), Sandia National Laboratories (SNL), DCH Technology (DCHT), and Air Products and Chemicals Inc. (APCI), have aggressively pursued engineering solutions to eliminate barriers to solid-state chemiresistor hydrogen sensor technology. The metallurgical effects of alloying palladium with nickel have been shown to prevent phase transitions in the thin films at high H2 overpressures, making the devices more suitable for IOF process conditions. We investigated the use of thin, semi-permeable membranes that protect the catalytic surface from poisoning or other undesirable surface reactions that would otherwise reduce sensitivity or operability in harsh IOF process environments. The results of this project have provided new insight into the effects of metallurgy and protective coatings on device behavior, and open new avenues for research in this field. Commercialization of this sensor technology could be easily achieved, although not yet realized. The benefits to society, once this technology is commercialized, is a dramatic cost and energy savings to the industry, which employs these sensors. In addition, the fundamental understandings gained in this program could have an impact on both cost and safety in the future hydrogen economy utilizing hydrogen fuel cells and hydrogen storage.

  8. Characterization of a soluble, catalytically active form of Escherichia coli leader peptidase: requirement of detergent or phospholipid for optimal activity.

    PubMed

    Tschantz, W R; Paetzel, M; Cao, G; Suciu, D; Inouye, M; Dalbey, R E

    1995-03-28

    Leader peptidase is a novel serine protease in Escherichia coli, which functions to cleave leader sequences from exported proteins. Its catalytic domain extends into the periplasmic space and is anchored to the membrane by two transmembrane segments located at the N-terminal end of the protein. At present, there is no information on the structure of the catalytic domain. Here, we report on the properties of a soluble form of leader peptidase (delta 2-75), and we compare its properties to those of the wild-type enzyme. We find that the truncated leader peptidase has a kcat of 3.0 S-1 and a Km of 32 microM with a pro-OmpA nuclease A substrate. In contrast to the wild-type enzyme (pI of 6.8), delta 2-75 is water-soluble and has an acidic isoelectric point of 5.6. We also show with delta 2-75 that the replacement of serine 90 and lysine 145 with alanine residues results in a 500-fold reduction in activity, providing further evidence that leader peptidase employs a catalytic serine/lysine dyad. Finally, we find that the catalysis of delta 2-75 is accelerated by the presence of the detergent Triton X-100, regardless if the substrate is pro-OmpA nuclease A or a peptide substrate. Triton X-100 is required for optimal activity of delta 2-75 at a level far below the critical micelle concentration. Moreover, we find that E. coli phospholipids stimulate the activity of delta 2-75, suggesting that phospholipids may play an important physiological role in the catalytic mechanism of leader peptidase. PMID:7696258

  9. Final Report for DE-FG02-04ER15626: P-type ATPases in Plants – Role of Lipid Flippases in Membrane Biogenesis

    SciTech Connect

    Harper, Jeffrey F.

    2015-02-24

    The long-range goal of the research is to understand the structure and biological functions of different P-type ATPases (ion pumps) in plant cells, and to use that knowledge to enhance the production of bioenergy from plants, or plant-research inspired technologies. Ptype ATPases include ion pumps that specifically transport H+, Ca2+, Zn2+, Cu2+, K+, or Na+, as well as at least one unusual subfamily that appears to function as lipid flippases, flipping specific lipids from one side of a membrane bilayer to the other. As a group, P-type ATPases are thought to consume more than 1/3 of the cellular ATP in typical eukaryotic cells. Recent research in the Harper lab focused on understanding the biochemical and biological functions of P-type ATPases that flip lipids. These flippases belong to the P4 subfamily of P-type ATPases. The activity of lipid flippases is thought to induce membrane curvature and/or create an asymmetry in which certain lipid head groups are preferential exposed to one surface or the other. In Arabidopsis thaliana there are 12 members of this family referred to as Aminophospholipid ATPase (ALA) 1 to ALA12. Using genetic knockouts, the Harper lab has established that this unusual subfamily of P-type ATPases are critical for plants to cope with even modest changes in temperature (e.g., down to 15°C, or up to 30°C). In addition, members of one subclade are critical for cell expansion, and loss of function mutants result in severe dwarfism. Other members of this same sub-clade are critical for pollen tube growth, and loss of function mutants are sterile under conditions of hot days and cold nights. While the cellular processes that depend on lipid flippases are still unclear, the genetic analysis of loss of function mutants clearly show they are of fundamental importance to plant growth and response to the environment.

  10. Solubilization of trace organics in block copolymer micelles for environmental separation using membrane extraction principles. Final report, May 1, 1992--April 30, 1995

    SciTech Connect

    Hatton, T.A.

    1998-09-01

    The solubilization of a range of polycyclic aromatic hydrocarbons in block copolymer micelles has been studied as a function of polymer composition, architecture, and temperature. Micelle formation is favored at high temperatures, leading to significant enhancements in solubilization capacity. At low temperatures, however, micelles do not form and the solubilization capacity of the block copolymer solution for the organics is low; this provides a convenient method for the regeneration of micellar solutions used as solvents in the treatment of contaminated feed streams using membrane extraction principles. Other experiments and analysis point to the effectiveness of block copolymer micellar solutions as water-based adsorbents for the removal of trace organics from air streams. Theoretical calculations of the structure of block copolymer micelles in the presence and absence of solutes using self-consistent mean-field lattice theories and lattice Monte Carlo methods have successfully captured the trends observed with changing polymer composition and architecture, often quantitatively. The temperature and composition dependence of the micellar properties were determined by allowing the individual polymer segments to assume both polar and non-polar conformations.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. ``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.

  16. 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.

  17. MULTI-POLLUTANT CONTROL USING MEMBRANE--BASED UP-FLOW WET ELECTROSTATIC PRECIPITATION

    SciTech Connect

    James Reynolds

    2004-10-29

    This is the Final Report of the ''Multi-Pollutant Control Using Membrane-Based Up-flow Wet Electrostatic Precipitation'' project funded by the US Department of Energy's National Energy Technology Laboratory under DOE Award No. DE-FC26-02NT41592 to Croll-Reynolds Clean Air Technologies (CRCAT). In this 18 month project, CRCAT and its team members conducted detailed emission tests of metallic and new membrane collection material within a wet electrostatic precipitator (WESP) at First Energy's Penn Power's Bruce Mansfield (BMP) plant in Shippingport, Pa. The Membrane WESP was designed to be as similar as the metallic WESP in terms of collection area, air-flow, and electrical characteristics. Both units are two-field units. The membrane unit was installed during the 2nd and 3rd quarters of 2003. Testing of the metallic unit was performed to create a baseline since the Mansfield plant had installed selective catalytic reduction equipment for NOx control and a sodium bisulfate injection system for SO3 control during the spring of 2003. Tests results on the metallic WESP were consistent with previous testing for PM2.5, SO3 mist and mercury. Testing on the membrane WESP demonstrated no adverse impact and equivalent removal efficiencies as that of the metallic WESP. Testing on both units was performed at 8,000 acfm and 15,000 acfm. Summary results are shown.

  18. Membrane electrode assembly for a fuel cell

    NASA Technical Reports Server (NTRS)

    Prakash, Surya (Inventor); Narayanan, Sekharipuram R. (Inventor); Atti, Anthony (Inventor); Olah, George (Inventor); Smart, Marshall C. (Inventor)

    2006-01-01

    A catalyst ink for a fuel cell including a catalytic material and poly(vinylidene fluoride). The ink may be applied to a substrate to form an electrode, or bonded with other electrode layers to form a membrane electrode assembly (MEA).

  19. Hybrid Amyloid Membranes for Continuous Flow Catalysis.

    PubMed

    Bolisetty, Sreenath; Arcari, Mario; Adamcik, Jozef; Mezzenga, Raffaele

    2015-12-29

    Amyloid fibrils are promising nanomaterials for technological applications such as biosensors, tissue engineering, drug delivery, and optoelectronics. Here we show that amyloid-metal nanoparticle hybrids can be used both as efficient active materials for wet catalysis and as membranes for continuous flow catalysis applications. Initially, amyloid fibrils generated in vitro from the nontoxic β-lactoglobulin protein act as templates for the synthesis of gold and palladium metal nanoparticles from salt precursors. The resulting hybrids possess catalytic features as demonstrated by evaluating their activity in a model catalytic reaction in water, e.g., the reduction of 4-nitrophenol into 4-aminophenol, with the rate constant of the reduction increasing with the concentration of amyloid-nanoparticle hybrids. Importantly, the same nanoparticles adsorbed onto fibrils surface show improved catalytic efficiency compared to the same unattached particles, pointing at the important role played by the amyloid fibril templates. Then, filter membranes are prepared from the metal nanoparticle-decorated amyloid fibrils by vacuum filtration. The resulting membranes serve as efficient flow catalysis active materials, with a complete catalytic conversion achieved within a single flow passage of a feeding solution through the membrane. PMID:26673736

  20. Advanced coal liquefaction. Final quarterly report, October 1, 1995--December 31, 1995

    SciTech Connect

    1995-12-31

    In this quarter, we successfully prepared a granular catalyst required for decomposing compound number 9 in the catalytic membrane reactor. The surface and porous properties of this catalyst are similar to the properties of the ceramic membrane surface. Thus, the catalytic reaction pattern from the granular catalyst is expected to be similar to that from the membranes surface. Further, this catalyst demonstrates a typical property of acid catalysts. The catalytic membrane reactor activity will be resumed in the next quarter using the catalyst prepared in this quarter. In addition, carbon coating of this catalyst did not reduce its acidic property significantly. More study will performed to determine the role of the carbon coating.

  1. 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.

  2. Photobiodegradation of chlorinated water pollutants by a combined TiO2-polyaniline-enzyme catalytic system

    NASA Astrophysics Data System (ADS)

    Campanella, Luigi; Crescentini, G.; Militerno, S.

    1995-10-01

    The removal of xenobiotic compounds, such as chlorophenols and pesticides, from municipal and industrial wastewaters is an important task because of the toxicity and the tendency to bioaccumulation of these compounds. Among the several methods proposed, photodegradation catalyzed by suspended inorganic semiconductors (i.e. TiO2) has lately received wide attention because this process is fast, leads to non-toxic final products and shows a high degradation efficiency. In this work, the results obtained in the photodegradation of monochlorophenols using a new catalyst, made of TiO2 and polyaniline both immobilized on a polyvinylchloride (PVC) membrane, in presence (and in absence) of an enzyme are presented. Different enzymes have been tested by adding 5, 10 or 15 U/mL to 50 mL of aqueous solution (1 multiplied by 10-4 mol/L) of o-chloro-phenol containing the catalytic membrane. The samples were irradiated using a QUV panel accelerated weathering tester, which simulates very well the solar radiation up to lambda equals 400 nm and HPLC was used to measure the variation of the compound's concentration with the time. While some enzymes (i.e., peroxidase) do not improve the photodegradation process since they do not survive under the irradiation conditions used, some of them show marked effect both in terms of rate degradation and time required to reach the total degradation of the compound examined. For example, the addition of Laccase reduces the 100% degradation time from 35 hrs to about 20 hrs. Attempts to immobilize the enzyme on the catalytic membrane (by adsorption) have been carried out and the performance of the catalyst with non-immobilized and immobilized enzyme has been studied.

  3. Mixed ionic and electronic conducting ceramic membranes for hydrocarbon processing

    DOEpatents

    Van Calcar, Pamela; Mackay, Richard; Sammells, Anthony F.

    2002-01-01

    The invention relates to mixed phase materials for the preparation of catalytic membranes which exhibit ionic and electronic conduction and which exhibit improved mechanical strength compared to single phase ionic and electronic conducting materials. The mixed phase materials are useful for forming gas impermeable membranes either as dense ceramic membranes or as dense thin films coated onto porous substrates. The membranes and materials of this invention are useful in catalytic membrane reactors in a variety of applications including synthesis gas production. One or more crystalline second phases are present in the mixed phase material at a level sufficient to enhance the mechanical strength of the mixture to provide membranes for practical application in CMRs.

  4. 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

  5. Membrane Processes.

    PubMed

    Pellegrin, Marie-Laure; Sadler, Mary E; Greiner, Anthony D; Aguinaldo, Jorge; Min, Kyungnan; Zhang, Kai; Arabi, Sara; Burbano, Marie S; Kent, Fraser; Shoaf, Robert

    2015-10-01

    This review, for literature published in 2014, contains information related to membrane processes for municipal and industrial applications. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following topics: pretreatment, membrane bioreactor (MBR) configuration, design, nutrient removal, operation, industrial treatment, fixed film and anaerobic membrane systems, reuse, microconstituents removal, membrane technology advances, membrane fouling, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include: Biological Fixed-Film Systems, Activated Sludge and Other Aerobic Suspended Culture Processes, Anaerobic Processes, Water Reclamation and Reuse. The following sections might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants. PMID:26420079

  6. Membrane Processes.

    PubMed

    Pellegrin, Marie-Laure; Burbano, Marie S; Sadler, Mary E; Diamond, Jason; Baker, Simon; Greiner, Anthony D; Arabi, Sara; Wong, Joseph; Doody, Alexandra; Padhye, Lokesh P; Sears, Keith; Kistenmacher, Peter; Kent, Fraser; Tootchi, Leila; Aguinaldo, Jorge; Saddredini, Sara; Schilling, Bill; Min, Kyungnan; McCandless, Robert; Danker, Bryce; Gamage, Neranga P; Wang, Sunny; Aerts, Peter

    2016-10-01

    This review, for literature published in 2015, contains information related to membrane processes for municipal and industrial applications. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following topics: pretreatment, membrane bioreactor (MBR) configuration, design, nutrient removal, operation, industrial treatment, anaerobic membrane systems, reuse, microconstituents removal, membrane technology advances, membrane fouling, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include: Biological Fixed-Film Systems, Activated Sludge and Other Aerobic Suspended Culture Processes, Anaerobic Processes, Water Reclamation and Reuse. The following sections might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants. PMID:27620084

  7. Multicomponent membranes

    DOEpatents

    Kulprathipanja, Santi; Kulkarni, Sudhir S.; Funk, Edward W.

    1988-01-01

    A multicomponent membrane which may be used for separating various components which are present in a fluid feed mixture comprises a mixture of a plasticizer such as a glycol and an organic polymer cast upon a porous organic polymer support. The membrane may be prepared by casting an emulsion or a solution of the plasticizer and polymer on the porous support, evaporating the solvent and recovering the membrane after curing.

  8. 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

  9. Membrane-electrode assemblies for electrochemical cells

    DOEpatents

    Swathirajan, Sundararajan; Mikhail, Youssef M.

    1993-01-01

    A combination, unitary, membrane and electrode assembly with a solid polymer electrolyte membrane, and first and second electrodes at least partially embedded in opposed surfaces of the membrane. The electrodes each comprise a respective group of finely divided carbon particles, very finely divided catalytic particles supported on internal and external surfaces of the carbon particles and a proton conductive material intermingled with the catalytic and carbon particles. A first group of finely divided carbon particles forming the first electrode has greater water attraction and retention properties, and is more hydrophilic than a second group of carbon particles forming the second electrode. In a preferred method, the membrane electrode assembly of the invention is prepared by forming a slurry of proton conductive material and at least one group of the carbon and catalyst particles. The slurry is applied to the opposed surfaces of the membrane and heated while being pressed to the membrane for a time and at a temperature and compressive load sufficient to embed at least a portion of the particles into the membrane.

  10. 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

  11. Thermodynamics of Membrane Insertion and Refolding of the Diphtheria Toxin T-Domain.

    PubMed

    Vargas-Uribe, Mauricio; Rodnin, Mykola V; Öjemalm, Karin; Holgado, Aurora; Kyrychenko, Alexander; Nilsson, IngMarie; Posokhov, Yevgen O; Makhatadze, George; von Heijne, Gunnar; Ladokhin, Alexey S

    2015-06-01

    The diphtheria toxin translocation (T) domain inserts into the endosomal membrane in response to the endosomal acidification and enables the delivery of the catalytic domain into the cell. The insertion pathway consists of a series of conformational changes that occur in solution and in the membrane and leads to the conversion of a water-soluble state into a transmembrane state. In this work, we utilize various biophysical techniques to characterize the insertion pathway from the thermodynamic perspective. Thermal and chemical unfolding measured by differential scanning calorimetry, circular dichroism, and tryptophan fluorescence reveal that the free energy of unfolding of the T-domain at neutral and mildly acidic pH differ by 3-5 kcal/mol, depending on the experimental conditions. Fluorescence correlation spectroscopy measurements show that the free energy change from the membrane-competent state to the interfacial state is approximately -8 kcal/mol and is pH-independent, while that from the membrane-competent state to the transmembrane state ranges between -9.5 and -12 kcal/mol, depending on the membrane lipid composition and pH. Finally, the thermodynamics of transmembrane insertion of individual helices was tested using an in vitro assay that measures the translocon-assisted integration of test sequences into the microsomal membrane. These experiments suggest that even the most hydrophobic helix TH8 has only a small favorable free energy of insertion. The free energy for the insertion of the consensus insertion unit TH8-TH9 is slightly more favorable, yet less favorable than that measured for the entire protein, suggesting a cooperative effect for the membrane insertion of the helices of the T-domain. PMID:25281329

  12. Synthesis of catalytic materials in flames: opportunities and challenges.

    PubMed

    Koirala, Rajesh; Pratsinis, Sotiris E; Baiker, Alfons

    2016-05-31

    The proven capacity of flame aerosol technology for rapid and scalable synthesis of functional nanoparticles makes it ideal for the manufacture of an array of heterogeneous catalysts. Capitalizing on the high temperature environment, rapid cooling and intimate component mixing at either atomic or nano scale, novel catalysts with unique physicochemical properties have been made using flame processes. This tutorial review covers the main features of flame synthesis and illustrates how the physical and chemical properties of as-synthesized solid catalytic materials can be controlled by proper choice of the process parameters. Gas phase particle formation mechanisms and the effect of synthesis conditions (reactor configuration, precursor and dispersion gas flow rates, temperature and concentration fields) on the structural, chemical and catalytic properties of as-prepared materials are discussed. Finally, opportunities and challenges offered by flame synthesis of catalytic materials are addressed. PMID:27108487

  13. Development of a methane premixed catalytic burner for household applications

    SciTech Connect

    Cerri, I.; Saracco, G.; Geobaldo, F.; Specchia, V.

    2000-01-01

    A catalytic premixed burner prototype for domestic-boiler applications was developed on the basis of a perovskite-type catalyst (LaMnO{sub 3}) deposited over a FeCrAlloy fiber panel. An economic and simple catalyst-deposition route, based on in situ pyrolysis of suitable precursors, was conceived and optimized on purpose. Finally, a catalytic burner and a reference noncatalytic one were comparatively tested in a pilot plant (maximum power, 30 kW, corresponding to about 2,000 kW/m{sup 2}). The catalytic burner allowed a strong reduction of CO and unburned hydrocarbon (HC) emissions to very low and acceptable levels (down to 3--5 times lower than those of the noncatalytic burner) when operated below 800 kW/m{sup 2}. In these conditions, the NO{sub x} emissions remained quite acceptable and practically unaffected by the presence of the catalyst.

  14. Ultra Low NOx Catalytic Combustion for IGCC Power Plants

    SciTech Connect

    Shahrokh Etemad; Benjamin Baird; Sandeep Alavandi; William Pfefferle

    2008-03-31

    In order to meet DOE's goals of developing low-emissions coal-based power systems, PCI has further developed and adapted it's Rich-Catalytic Lean-burn (RCL{reg_sign}) catalytic reactor to a combustion system operating on syngas as a fuel. The technology offers ultra-low emissions without the cost of exhaust after-treatment, with high efficiency (avoidance of after-treatment losses and reduced diluent requirements), and with catalytically stabilized combustion which extends the lower Btu limit for syngas operation. Tests were performed in PCI's sub-scale high-pressure (10 atm) test rig, using a two-stage (catalytic then gas-phase) combustion process for syngas fuel. In this process, the first stage consists of a fuel-rich mixture reacting on a catalyst with final and excess combustion air used to cool the catalyst. The second stage is a gas-phase combustor, where the air used for cooling the catalyst mixes with the catalytic reactor effluent to provide for final gas-phase burnout and dilution to fuel-lean combustion products. During testing, operating with a simulated Tampa Electric's Polk Power Station syngas, the NOx emissions program goal of less than 0.03 lbs/MMBtu (6 ppm at 15% O{sub 2}) was met. NOx emissions were generally near 0.01 lbs/MMBtu (2 ppm at 15% O{sub 2}) (PCI's target) over a range on engine firing temperatures. In addition, low emissions were shown for alternative fuels including high hydrogen content refinery fuel gas and low BTU content Blast Furnace Gas (BFG). For the refinery fuel gas increased resistance to combustor flashback was achieved through preferential consumption of hydrogen in the catalytic bed. In the case of BFG, stable combustion for fuels as low as 88 BTU/ft{sup 3} was established and maintained without the need for using co-firing. This was achieved based on the upstream catalytic reaction delivering a hotter (and thus more reactive) product to the flame zone. The PCI catalytic reactor was also shown to be active in ammonia

  15. Molecular Physiology of Membrane Guanylyl Cyclase Receptors.

    PubMed

    Kuhn, Michaela

    2016-04-01

    cGMP controls many cellular functions ranging from growth, viability, and differentiation to contractility, secretion, and ion transport. The mammalian genome encodes seven transmembrane guanylyl cyclases (GCs), GC-A to GC-G, which mainly modulate submembrane cGMP microdomains. These GCs share a unique topology comprising an extracellular domain, a short transmembrane region, and an intracellular COOH-terminal catalytic (cGMP synthesizing) region. GC-A mediates the endocrine effects of atrial and B-type natriuretic peptides regulating arterial blood pressure/volume and energy balance. GC-B is activated by C-type natriuretic peptide, stimulating endochondral ossification in autocrine way. GC-C mediates the paracrine effects of guanylins on intestinal ion transport and epithelial turnover. GC-E and GC-F are expressed in photoreceptor cells of the retina, and their activation by intracellular Ca(2+)-regulated proteins is essential for vision. Finally, in the rodent system two olfactorial GCs, GC-D and GC-G, are activated by low concentrations of CO2and by peptidergic (guanylins) and nonpeptidergic odorants as well as by coolness, which has implications for social behaviors. In the past years advances in human and mouse genetics as well as the development of sensitive biosensors monitoring the spatiotemporal dynamics of cGMP in living cells have provided novel relevant information about this receptor family. This increased our understanding of the mechanisms of signal transduction, regulation, and (dys)function of the membrane GCs, clarified their relevance for genetic and acquired diseases and, importantly, has revealed novel targets for therapies. The present review aims to illustrate these different features of membrane GCs and the main open questions in this field. PMID:27030537

  16. Inorganic membranes and solid state sciences

    NASA Astrophysics Data System (ADS)

    Cot, Louis; Ayral, André; Durand, Jean; Guizard, Christian; Hovnanian, Nadine; Julbe, Anne; Larbot, André

    2000-05-01

    The latest developments in inorganic membranes are closely related to recent advances in solid state science. Sol-gel processing, plasma-enhanced chemical vapor deposition and hydrothermal synthesis are methods that can be used for inorganic membrane preparation. Innovative concepts from material science (templating effect, nanophase materials, growing of continuous zeolite layers, hybrid organic-inorganic materials) have been applied by our group to the preparation of inorganic membrane materials. Sol-gel-derived nanophase ceramic membranes are presented with current applications in nanofiltration and catalytic membrane reactors. Silica membranes with an ordered porosity, due to liquid crystal phase templating effect, are described with potential application in pervaporation. Defect-free and thermally stable zeolite membranes can be obtained through an original synthesis method, in which zeolite crystals are grown inside the pores of a support. Hybrid organic-inorganic materials with permselective properties for gas separation and facilitated transport of solutes in liquid media, have been successfully adapted to membrane applications. Potential membrane developments offered by CVD deposition techniques are also illustrated through several examples related to the preparation of purely inorganic and hybrid organic-inorganic membrane materials.

  17. Develpment of Higher Temperature Membrane and Electrode Assembly (MEA) for Proton Exchange Membrane Fuel Cell Devices

    SciTech Connect

    Susan Agro, Anthony DeCarmine, Shari Williams

    2005-12-30

    Our work will fucus on developing higher temperature MEAs based on SPEKK polymer blends. Thse MEAs will be designed to operatre at 120 degrees C Higher temperatures, up to 200 degrees C will also be explored. This project will develop Nafion-free MEAs using only SPEKK blends in both membrane and catalytic layers.

  18. Crystalline Membranes

    NASA Technical Reports Server (NTRS)

    Tsapatsis, Michael (Inventor); Lai, Zhiping (Inventor)

    2008-01-01

    In certain aspects, the invention features methods for forming crystalline membranes (e.g., a membrane of a framework material, such as a zeolite) by inducing secondary growth in a layer of oriented seed crystals. The rate of growth of the seed crystals in the plane of the substrate is controlled to be comparable to the rate of growth out of the plane. As a result, a crystalline membrane can form a substantially continuous layer including grains of uniform crystallographic orientation that extend through the depth of the layer.

  19. 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.

  20. Membrane Binding Events in the Initiation and Propagation Phases of Tissue Factor-initiated Zymogen Activation under Flow*

    PubMed Central

    Haynes, Laura M.; Dubief, Yves C.; Mann, Kenneth G.

    2012-01-01

    This study investigates the dynamics of zymogen activation when both extrinsic tenase and prothrombinase are assembled on an appropriate membrane. Although the activation of prothrombin by surface-localized prothrombinase is clearly mediated by flow-induced dilutional effects, we find that when factor X is activated in isolation by surface-localized extrinsic tenase, it exhibits characteristics of diffusion-mediated activation in which diffusion of substrate to the catalytically active region is rate-limiting. When prothrombin and factor X are activated coincident with each other, competition for available membrane binding sites masks the diffusion-limiting effects of factor X activation. To verify the role of membrane binding in the activation of factor X by extrinsic tenase under flow conditions, we demonstrate that bovine lactadherin competes for both factor X and Xa binding sites, limiting factor X activation and forcing the release of bound factor Xa from the membrane at a venous shear rate (100 s−1). Finally, we present steady-state models of prothrombin and factor X activation under flow showing that zymogen and enzyme membrane binding events further regulate the coagulation process in an open system representative of the vasculature geometry. PMID:22187432

  1. ULTRA LOW NOx CATALYTIC COMBUSTION FOR IGCC POWER PLANTS

    SciTech Connect

    Lance L. Smith

    2004-03-01

    Tests were performed in PCI's sub-scale high-pressure (10 atm) test rig, using PCI's two-stage (catalytic / gas-phase) combustion process for syngas fuel. In this process, the first stage is a Rich-Catalytic Lean-burn (RCL{trademark}) catalytic reactor, wherein a fuel-rich mixture contacts the catalyst and reacts while final and excess combustion air cool the catalyst. The second stage is a gas-phase combustor, wherein the catalyst cooling air mixes with the catalytic reactor effluent to provide for final gas-phase burnout and dilution to fuel-lean combustion products. During the reporting period, PCI successfully achieved NOx = 0.011 lbs/MMBtu at 10 atm pressure (corresponding to 2.0 ppm NOx corrected to 15% O{sub 2} dry) with near-zero CO emissions, surpassing the project goal of < 0.03 lbs/MMBtu NOx. These emissions levels were achieved at scaled (10 atm, sub-scale) baseload conditions corresponding to Tampa Electric's Polk Power Station operation on 100% syngas (no co-firing of natural gas).

  2. Biological membranes

    PubMed Central

    Watson, Helen

    2015-01-01

    Biological membranes allow life as we know it to exist. They form cells and enable separation between the inside and outside of an organism, controlling by means of their selective permeability which substances enter and leave. By allowing gradients of ions to be created across them, membranes also enable living organisms to generate energy. In addition, they control the flow of messages between cells by sending, receiving and processing information in the form of chemical and electrical signals. This essay summarizes the structure and function of membranes and the proteins within them, and describes their role in trafficking and transport, and their involvement in health and disease. Techniques for studying membranes are also discussed. PMID:26504250

  3. Membranous nephropathy

    MedlinePlus

    ... to reduce cholesterol and triglyceride levels (most often statins) may be recommended. A low-salt diet may ... of membranous nephropathy Your symptoms get worse or don't go away You develop new symptoms You have ...

  4. Catalytic decomposition of petroleum into natural gas

    SciTech Connect

    Mango, F.D.; Hightower, J.

    1997-12-01

    Petroleum is believed to be unstable in the earth, decomposing to lighter hydrocarbons at temperatures > 150{degrees}C. Oil and gas deposits support this view: gas/oil ratios and methane concentrations tend to increase with depth above 150{degrees}C. Although oil cracking is suggested and receives wide support, laboratory pyrolysis does not give products resembling natural gas. Moreover, it is doubtful that the light hydrocarbons in wet gas (C{sub 2}-C{sub 4}) could decompose over geologic time to dry gas (>95% methane) without catalytic assistance. We now report the catalytic decomposition of crude oil to a gas indistinguishable from natural gas. Like natural gas in deep basins, it becomes progressively enriched in methane: initially 90% (wet gas) to a final composition of 100% methane (dry gas). To our knowledge, the reaction is unprecedented and unexpectedly robust (conversion of oil to gas is 100% in days, 175{degrees}C) with significant implications regarding the stability of petroleum in sedimentary basins. The existence or nonexistence of oil in the deep subsurface may not depend on the thermal stability of hydrocarbons as currently thought. The critical factor could be the presence of transition metal catalysts which destabilize hydrocarbons and promote their decomposition to natural gas.

  5. Biogenesis and Assembly of Eukaryotic Cytochrome c Oxidase Catalytic Core

    PubMed Central

    Soto, Ileana C.; Fontanesi, Flavia; Liu, Jingjing; Barrientos, Antoni

    2011-01-01

    Eukaryotic cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial respiratory chain. COX is a multimeric enzyme formed by subunits of dual genetic origin which assembly is intricate and highly regulated. The COX catalytic core is formed by three mitochondrial DNA encoded subunits, Cox1, Cox2 and Cox3, conserved in the bacterial enzyme. Their biogenesis requires the action of messenger-specific and subunit-specific factors which facilitate the synthesis, membrane insertion, maturation or assembly of the core subunits. The study of yeast strains and human cell lines from patients carrying mutations in structural subunits and COX assembly factors has been invaluable to identify these ancillary factors. Here we review the current state of knowledge of the biogenesis and assembly of the eukaryotic COX catalytic core and discuss the degree of conservation of the players and mechanisms operating from yeast to human. PMID:21958598

  6. Peptide Membranes in Chemical Evolution*

    PubMed Central

    Childers, W. Seth; Ni, Rong; Mehta, Anil K.; Lynn, David G.

    2009-01-01

    SUMMARY Simple surfactants achieve remarkable long-range order in aqueous environments. This organizing potential is seen most dramatically in biological membranes where phospholipid assemblies both define cell boundaries and provide a ubiquitous structural scaffold for controlling cellular chemistry. Here we consider simple peptides that also spontaneously assemble into exceptionally ordered scaffolds, and review early data suggesting that these structures maintain the functional diversity of proteins. We argue that such scaffolds can achieve the required molecular order and catalytic agility for the emergence of chemical evolution. PMID:19879180

  7. 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.

  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

    first case. Finally, the results show that different initial surface-species distribution leads to different steady-states under certain conditions. These results demonstrate the utility of a lumped two-phase model of a transient catalytic combustor with detailed chemistry.

  9. Catalytic Conversion of Biomass to Fuels and Chemicals Using Ionic Liquids

    SciTech Connect

    Liu, Wei; Zheng, Richard; Brown, Heather; Li, Joanne; Holladay, John; Cooper, Alan; Rao, Tony

    2012-04-13

    This project provides critical innovations and fundamental understandings that enable development of an economically-viable process for catalytic conversion of biomass (sugar) to 5-hydroxymethylfurfural (HMF). A low-cost ionic liquid (Cyphos 106) is discovered for fast conversion of fructose into HMF under moderate reaction conditions without any catalyst. HMF yield from fructose is almost 100% on the carbon molar basis. Adsorbent materials and adsorption process are invented and demonstrated for separation of 99% pure HMF product and recovery of the ionic liquid from the reaction mixtures. The adsorbent material appears very stable in repeated adsorption/regeneration cycles. Novel membrane-coated adsorbent particles are made and demonstrated to achieve excellent adsorption separation performances at low pressure drops. This is very important for a practical adsorption process because ionic liquids are known of high viscosity. Nearly 100% conversion (or dissolution) of cellulose in the catalytic ionic liquid into small molecules was observed. It is promising to produce HMF, sugars and other fermentable species directly from cellulose feedstock. However, several gaps were identified and could not be resolved in this project. Reaction and separation tests at larger scales are needed to minimize impacts of incidental errors on the mass balance and to show 99.9% ionic liquid recovery. The cellulose reaction tests were troubled with poor reproducibility. Further studies on cellulose conversion in ionic liquids under better controlled conditions are necessary to delineate reaction products, dissolution kinetics, effects of mass and heat transfer in the reactor on conversion, and separation of final reaction mixtures.

  10. High temperature ceramic membrane reactors for coal liquid upgrading. Quarterly report No. 1, September 21, 1989--December 20, 1989

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    In this project we well evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated. (VC)

  11. 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

  12. 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

  13. 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.

  14. Catalytic multi-stage liquefaction (CMSL). Final report

    SciTech Connect

    1996-11-01

    The 17-day bench run CMSL-6 (227-83), on Black Thunder Mine subbituminous coal and with an approximate space velocity of 481 kg/hr/m{sup 3} (30 lb/hr/ft{sup 3}), tested the performance of a dispersed slurry catalyst in powdered form added to the first stage thermal reactor. This catalyst, based on molybdenum-containing sulfated iron oxide prepared at HTI, had about 15% moisture, 43% Fe and 7% Mo with a BET surface area of about 40 m{sup 2}/g. The second stage reactor had a partially deactivated Shell S-317 catalyst (initial age=520 kg-coal/kg-catalyst) to make the effects of the slurry catalyst more apparent and to attain a realistic equilibrium catalyst age sooner. An in-line hydrotreater was successfully employed during this run to treat atmospheric still overhead and separator overhead products. No interstage product separator was utilized in this run. For the first run condition, the catalyst additive rate was 1400-4300 ppm (of coal) Fe with 200-700 ppm Mo using a slurrying oil recycle consisting of 60% of filtered product slurry and 40% of ashy recycle (unfiltered product slurry) at a relatively low severity with first and second stage temperatures of 427{degrees}C and 413{degrees}C (800{degrees}F and 775{degrees}F), respectively. After that the additive rate was lowered to 700 ppm Fe with 100 ppm of Mo and the severity was increased with first and second stage temperatures of 441{degrees}C and 427{degrees}C (825{degrees}F and 800{degrees}F) respectively. The proportion of ashy recycle was maintained at 40% in Condition 2, and it was lowered to 25% in Condition 3. In Condition 4, the proportion of ashy recycle was set at 50%, but, because of slowing of the product slurry filtration, vacuum distillate recycle (and makeup oil) was substituted for the filtered liquid constituent of the recycled oil. With the changes of the proportion of ashy recycle the total slurry catalyst in the system (added and recycled) ranged from 860 to 6345 ppm Fe with 140 to 1030 ppm Mo.

  15. Fundamental studies of catalytic processing of synthetic liquids. Final report

    SciTech Connect

    Watson, P.R.

    1994-06-15

    Liquids derived from coal contain relatively high amounts of oxygenated organic compounds, mainly in the form of phenols and furans that are deleterious to the stability and quality of these liquids as fuels. Hydrodeoxygenation (HDO) using Mo/W sulfide catalysts is a promising method to accomplish this removal, but our understanding of the reactions occurring on the catalyst surface during HDO is very limited. Rather than attempting to examine the complexities of real liquids and catalysts we have adopted an approach here using model systems amenable to surface-sensitive techniques that enable us to probe in detail the fundamental processes occurring during HDO at the surfaces of well-defined model catalysts. The results of this work may lead to the development of more efficient, selective and stable catalysts. Above a S/Mo ratio of about 0.5 ML, furan does not adsorb on sulfided Mo surfaces; as the sulfur coverage is lowered increasing amounts of furan can be adsorbed. Temperature-programmed reaction spectroscopy (TPRS) reveals that C-H, C-C and C-O bond scission occurs on these surfaces. Auger spectra show characteristic changes in the nature and amount of surface carbon. Comparisons with experiments carried out with CO, H{sub 2} and alkenes show that reaction pathways include -- direct abstraction of CO at low temperatures; cracking and release of hydrogen below its normal desorption temperature; dehydrogenatin of adsorbed hydrocarbon fragments; recombination of C and O atoms and dissolution of carbon into the bulk at high temperatures. Performing the adsorption or thermal reaction in 10{sup {minus}5} torr of hydrogen does not change the mode of reaction significantly.

  16. Control of catalytic hydrotreating selectivity with ammonia. Final technical report

    SciTech Connect

    Satterfield, C.N.; Lee, C.; Gultekin, S.

    1993-11-01

    The purpose of this study was to explore the possibility of control of product selectivity in the hydroprocessing of coal liquids and related substances by adding small amounts of ammonia. Quinoline was used in this study and in many others as representative of heterocyclic N compounds found in coal liquids. Coal liquids also contain hydroxy pyridines, but by studies with 8-OH quinoline, a representative compound (Part I), we demonstrated that the OH group was rapidly removed at the beginning of reaction to form quinoline, which reacted in the same manner as quinoline fed as such. In Part II we showed that in a mixture of naphthalene and quinoline, with the addition of ammonia there is an operating region in which complete HDN of quinoline can be achieved, but with greater conversion of naphthalene to tetralin instead of to decalin than was the case in the absence of added ammonia. This is of some significance to coal liquefaction since tetralin is a good hydrogen donor, but decalin is not. In Part III we showed that NH{sub 3} addition to a mixture of quinoline and phenanthrene provides an operating region where complete HDN of quinoline can be achieved with reduced formation of hydrogenated phenanthrenes and cracking to biphenyl. Part IV, a study of the hydrodeoxygenation (DHO) of dibenzofuran in the presence of naphthalene, showed that NH{sub 3} strongly inhibits HDO reactions and its effects on naphthalene here were much the same as in Part II. In Part V it was demonstrated that in the hydrotreating of propylbenzene, the addition of ammonia increased the selectivity towards ring hydrogenation (generally desired for reformulated motor fuels) and away from dealkylation (generally undesired), but the overall reaction rate at a fixed temperature drops substantially.

  17. Interaction of peptides with cell membranes: insights from molecular modeling

    NASA Astrophysics Data System (ADS)

    Li, Zhen-lu; Ding, Hong-ming; Ma, Yu-qiang

    2016-03-01

    The investigation of the interaction of peptides with cell membranes is the focus of active research. It can enhance the understanding of basic membrane functions such as membrane transport, fusion, and signaling processes, and it may shed light on potential applications of peptides in biomedicine. In this review, we will present current advances in computational studies on the interaction of different types of peptides with the cell membrane. Depending on the properties of the peptide, membrane, and external environment, the peptide-membrane interaction shows a variety of different forms. Here, on the basis of recent computational progress, we will discuss how different peptides could initiate membrane pores, translocate across the membrane, induce membrane endocytosis, produce membrane curvature, form fibrils on the membrane surface, as well as interact with functional membrane proteins. Finally, we will present a conclusion summarizing recent progress and providing some specific insights into future developments in this field.

  18. Method for low temperature catalytic production of hydrogen

    DOEpatents

    Mahajan, Devinder

    2003-07-22

    The invention provides a process for the catalytic production of a hydrogen feed by exposing a hydrogen feed to a catalyst which promotes a base-catalyzed water-gas-shift reaction in a liquid phase. The hydrogen feed can be provided by any process known in the art of making hydrogen gas. It is preferably provided by a process that can produce a hydrogen feed for use in proton exchange membrane fuel cells. The step of exposing the hydrogen feed takes place preferably from about 80.degree. C. to about 150.degree. C.

  19. Favorable effect of in-situ generated platinum in the membrane on fuel cell membrane durability

    NASA Astrophysics Data System (ADS)

    Macauley, Natalia; Wong, Ka Hung; Watson, Mark; Kjeang, Erik

    2015-12-01

    The overall lifetime of polymer electrolyte fuel cells is often determined by the membrane durability. Platinum, which may dissolve from the catalyst layers during fuel cell operation and deposit in the membrane, has been shown to have both positive and negative effects on membrane stability. In the present work, we analyze what specific conditions are required in order to reach a favorable, membrane stabilizing effect with the controlled use of platinum in the membrane. Using accelerated membrane durability testing, field operated membrane samples, and electron microscopy, we demonstrate that a high platinum concentration with specific particle shapes and sizes is essential for enhanced membrane stability. Specifically, star shaped and dendritic particles with high particle density and high surface area are shown to be preferable. These particles contain high levels of Pt(111) and are expected to have high catalytic activity toward peroxide quenching and crossover gas consumption, thereby mitigating chemical membrane degradation. On the other hand, small, dispersed cubic particles are found to have no effect or the opposite, negative effect on membrane stability.

  20. 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.

  1. 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…

  2. 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.

  3. 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 ...

  4. Catalytic activity of human carbonic anhydrase isoform IX is displayed both extra- and intracellularly.

    PubMed

    Klier, Michael; Jamali, Somayeh; Ames, Samantha; Schneider, Hans-Peter; Becker, Holger M; Deitmer, Joachim W

    2016-01-01

    Most carbonic anhydrases catalyse the reversible conversion of carbon dioxide to protons and bicarbonate, either as soluble cytosolic enzymes, in or at intracellular organelles, or at the extracellular face of the cell membrane as membrane-anchored proteins. Carbonic anhydrase isoform IX (CA IX), a membrane-bound enzyme with catalytic activity at the extracellular membrane surface, has come to prominence in recent years because of its association with hypoxic tissue, particularly tumours, often indicating poor prognosis. We have evaluated the catalytic activity of CA IX heterologously expressed in Xenopus laevis oocytes by measuring the amplitude and rate of cytosolic pH changes as well as pH changes at the outer membrane surface (pHs ) during addition and removal of 5% CO2 /25 mm HCO3-, and by mass spectrometry. Our results indicate both extracellular and intracellular catalytic activity of CA IX. Reduced rates of CO2 -dependent intracellular pH changes after knockdown of CA IX confirmed these findings in two breast cancer cell lines: MCF-7 and MDA-MB-231. Our results demonstrate a new function of CA IX that may be important in the search for therapeutic cancer drugs targeting CA IX. PMID:26470855

  5. Binding contribution between synaptic vesicle membrane and plasma membrane proteins in neurons: an AFM study.

    PubMed

    Sritharan, K C; Quinn, A S; Taatjes, D J; Jena, B P

    1998-01-01

    The final step in the exocytotic process is the docking and fusion of membrane-bound secretory vesicles at the cell plasma membrane. This docking and fusion is brought about by several participating vesicle membrane, plasma membrane and soluble cytosolic proteins. A clear understanding of the interactions between these participating proteins giving rise to vesicle docking and fusion is essential. In this study, the binding force profiles between synaptic vesicle membrane and plasma membrane proteins have been examined for the first time using the atomic force microscope. Binding force contributions of a synaptic vesicle membrane protein VAMP1, and the plasma membrane proteins SNAP-25 and syntaxin, are also implicated from these studies. Our study suggests that these three proteins are the major, if not the only contributors to the interactive binding force that exist between the two membranes. PMID:10452835

  6. Tubular hydrogen permeable metal foil membrane and method of fabrication

    DOEpatents

    Paglieri, Stephen N.; Birdsell, Stephen A.; Barbero, Robert S.; Snow, Ronny C.; Smith, Frank M.

    2006-04-04

    A tubular hydrogen permeable metal membrane and fabrication process comprises obtaining a metal alloy foil having two surfaces, coating the surfaces with a metal or metal alloy catalytic layer to produce a hydrogen permeable metal membrane, sizing the membrane into a sheet with two long edges, wrapping the membrane around an elongated expandable rod with the two long edges aligned and overlapping to facilitate welding of the two together, placing the foil wrapped rod into a surrounding fixture housing with the two aligned and overlapping foil edges accessible through an elongated aperture in the surrounding fixture housing, expanding the elongated expandable rod within the surrounding fixture housing to tighten the foil about the expanded rod, welding the two long overlapping foil edges to one another generating a tubular membrane, and removing the tubular membrane from within the surrounding fixture housing and the expandable rod from with the tubular membrane.

  7. Pore dynamics in lipid membranes

    NASA Astrophysics Data System (ADS)

    Gozen, I.; Dommersnes, P.

    2014-09-01

    Transient circular pores can open in plasma membrane of cells due to mechanical stress, and failure to repair such pores lead to cell death. Similar pores in the form of defects also exist among smectic membranes, such as in myelin sheaths or mitochondrial membranes. The formation and growth of membrane defects are associated with diseases, for example multiple sclerosis. A deeper understanding of membrane pore dynamics can provide a more refined picture of membrane integrity-related disease development, and possibly also treatment options and strategies. Pore dynamics is also of great importance regarding healthcare applications such as drug delivery, gene or as recently been implied, cancer therapy. The dynamics of pores significantly differ in stacks which are confined in 2D compared to those in cells or vesicles. In this short review, we will summarize the dynamics of different types of pores that can be observed in biological membranes, which include circular transient, fusion and hemi-fusion pores. We will dedicate a section to floral and fractal pores which were discovered a few years ago and have highly peculiar characteristics. Finally, we will discuss the repair mechanisms of large area pores in conjunction with the current cell membrane repair hypotheses.

  8. Membrane curvature at a glance.

    PubMed

    McMahon, Harvey T; Boucrot, Emmanuel

    2015-03-15

    Membrane curvature is an important parameter in defining the morphology of cells, organelles and local membrane subdomains. Transport intermediates have simpler shapes, being either spheres or tubules. The generation and maintenance of curvature is of central importance for maintaining trafficking and cellular functions. It is possible that local shapes in complex membranes could help to define local subregions. In this Cell Science at a Glance article and accompanying poster, we summarize how generating, sensing and maintaining high local membrane curvature is an active process that is mediated and controlled by specialized proteins using general mechanisms: (i) changes in lipid composition and asymmetry, (ii) partitioning of shaped transmembrane domains of integral membrane proteins or protein or domain crowding, (iii) reversible insertion of hydrophobic protein motifs, (iv) nanoscopic scaffolding by oligomerized hydrophilic protein domains and, finally, (v) macroscopic scaffolding by the cytoskeleton with forces generated by polymerization and by molecular motors. We also summarize some of the discoveries about the functions of membrane curvature, where in addition to providing cell or organelle shape, local curvature can affect processes like membrane scission and fusion as well as protein concentration and enzyme activation on membranes. PMID:25774051

  9. Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid.

    PubMed

    Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

    2016-07-01

    The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

  10. Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

    PubMed Central

    Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

    2016-01-01

    The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

  11. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    SciTech Connect

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.

  12. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    PubMed Central

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-01-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution. PMID:26673816

  13. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    NASA Astrophysics Data System (ADS)

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

    2015-12-01

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.

  14. Membrane magic

    SciTech Connect

    Buecker, B.

    2005-09-01

    The Kansas Power and Light Co.'s La Cyne generating station has found success with membrane filtration water pretreatment technology. The article recounts the process followed in late 2004 to install a Pall Aria 4 microfilter in Unit 1 makeup water system at the plant to produce cleaner water for reverse osmosis feed. 2 figs., 2 photos.

  15. Diffusiophoretic self-propulsion for partially catalytic spherical colloids.

    PubMed

    de Graaf, Joost; Rempfer, Georg; Holm, Christian

    2015-04-01

    Colloidal spheres with a partial platinum surface coating perform autophoretic motion when suspended in hydrogen peroxide solution. We present a theoretical analysis of the self-propulsion velocity of these particles using a continuum multi-component, self-diffusiophoretic model. With this model as a basis, we show how the slip-layer approximation can be derived and in which limits it holds. First, we consider the differences between the full multi-component model and the slip-layer approximation. Then the slip model is used to demonstrate and explore the sensitive nature of the particle's velocity on the details of the molecule-surface interaction. We find a strong asymmetry in the dependence of the colloid's velocity as a function of the level of catalytic coating, when there is a different interaction between the solute and solvent molecules and the inert and catalytic part of the colloid, respectively. The direction of motion can even be reversed by varying the level of the catalytic coating. Finally, we investigate the robustness of these results with respect to variations in the reaction rate near the edge between the catalytic and inert parts of the particle. Our results are of significant interest to the interpretation of experimental results on the motion of self-propelled particles. PMID:25751872

  16. Translocation of the Catalytic Domain of Diphtheria Toxin across Planar Phospholipid Bilayers by Its Own T Domain

    NASA Astrophysics Data System (ADS)

    Oh, Kyoung Joon; Senzel, Lisa; Collier, R. John; Finkelstein, Alan

    1999-07-01

    The T domain of diphtheria toxin is known to participate in the pH-dependent translocation of the catalytic C domain of the toxin across the endosomal membrane, but how it does so, and whether cellular proteins are also required for this process, remain unknown. Here, we report results showing that the T domain alone is capable of translocating the entire C domain across model, planar phospholipid bilayers in the absence of other proteins. The T domain therefore contains the entire molecular machinery for mediating transfer of the catalytic domain of diphtheria toxin across membranes.

  17. 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.

  18. 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.

  19. Membranes and separators for flowing-electrolyte batteries: A review

    NASA Astrophysics Data System (ADS)

    Arnold, C., Jr.; Assink, R. A.

    1983-04-01

    Membranes and separators for flowing electrolyte batteries are reviewed. Simple descriptive models are used to illustrate their functions and to distinguish between the operation of separators and membranes. Several studies which investigated the relationships between membrane structure and properties are reviewed. The many methods of separator and membrane preparation are compared. Finally, the specific separator and membrane requirements of three flowing electrolyte battery systems currently under development are described. Emphasis is placed on the mechanism of membrane fouling in iron/chromium redox battery, oxidative degradation of the membrane in the zinc/ferricyanide battery and separator impurities in the zinc/bromine battery.

  20. 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

  1. OXIDATIVE COUPLING OF METHANE USING INORGANIC MEMBRANE REACTORS

    SciTech Connect

    Dr. Y.H. Ma; Dr. W.R. Moser; Dr. A.G. Dixon; Dr. A.M. Ramachandra; Dr. Y. Lu; C. Binkerd

    1998-04-01

    The objective of this research is to study the oxidative coupling of methane in catalytic inorganic membrane reactors. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and higher yields than in conventional non-porous, co-feed, fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for the formation of CO{sub x} products. Such gas phase reactions are a cause of decreased selectivity in the oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Membrane reactor technology also offers the potential for modifying the membranes both to improve catalytic properties as well as to regulate the rate of the permeation/diffusion of reactants through the membrane to minimize by-product generation. Other benefits also exist with membrane reactors, such as the mitigation of thermal hot-spots for highly exothermic reactions such as the oxidative coupling of methane. The application of catalytically active inorganic membranes has potential for drastically increasing the yield of reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity.

  2. 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.

  3. 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.

  4. Role of acidic residues in helices TH8-TH9 in membrane interactions of the diphtheria toxin T domain.

    PubMed

    Ghatak, Chiranjib; Rodnin, Mykola V; Vargas-Uribe, Mauricio; McCluskey, Andrew J; Flores-Canales, Jose C; Kurnikova, Maria; Ladokhin, Alexey S

    2015-04-01

    The pH-triggered membrane insertion of the diphtheria toxin translocation domain (T domain) results in transferring the catalytic domain into the cytosol, which is relevant to potential biomedical applications as a cargo-delivery system. Protonation of residues is suggested to play a key role in the process, and residues E349, D352 and E362 are of particular interest because of their location within the membrane insertion unit TH8-TH9. We have used various spectroscopic, computational and functional assays to characterize the properties of the T domain carrying the double mutation E349Q/D352N or the single mutation E362Q. Vesicle leakage measurements indicate that both mutants interact with the membrane under less acidic conditions than the wild-type. Thermal unfolding and fluorescence measurements, complemented with molecular dynamics simulations, suggest that the mutant E362Q is more susceptible to acid destabilization because of disruption of native intramolecular contacts. Fluorescence experiments show that removal of the charge in E362Q, and not in E349Q/D352N, is important for insertion of TH8-TH9. Both mutants adopt a final functional state upon further acidification. We conclude that these acidic residues are involved in the pH-dependent action of the T domain, and their replacements can be used for fine tuning the pH range of membrane interactions. PMID:25875295

  5. Electrostatic interactions in catalytic centers of F1-ATPase

    NASA Astrophysics Data System (ADS)

    Pogrebnaya, Alexandra F.; Romanovsky, Yury M.; Tikhonov, Alexander N.

    2003-10-01

    F1-ATPase is one of the most important enzymes of membrane bioenergetics. F1-ATPase is the constituent complex that provides the ATP formation from ADP and inorganic phosphate (Pi) at the expense of energy of electrochemical gradient of hydrogen ions generated across the energy transducing mitochondrial, chloroplast or bacterial membrane. F1-ATPase is a reversible molecular machine that can work as a proton pump due to energy released in the course of ATP hydrolysis (ATPase reaction). The unusual feature of this enzyme is that it operates as a rotary molecular motor. Recently, using the fluorescence microscopy method for the real time visualization of molecular mobility of individual molecules, it was demonstrated directly that the ATP hydrolysis by F1-ATPase is accompanied by unidirectional rotations of mobile subunits (rotor) of F1F0-ATP synthase. In this work, we calculated the contribution of electrostatic interactions between charged groups of a substrate (MgATP), products molecules (MgADP and Pi), and charged amino acid residuals of ATPase molecule to the energy changes associated with the substrate binding and their chemical transformations in the catalytic centers located at the interface of α and β subunits of the enzyme (oligomer complex α3β3γ of bovine mitochondria ATPase). A catalytic cycle of ATP hydrolysis considered in our work includes conformational changes of α and β subunits caused by unidirectional rotations of an eccentric γ subunit. The knowledge of energy characteristics and force field in catalytic center of an enzyme in different conformational states may be important for further simulation dynamic properties of ATP synthase complex.

  6. [Membranous nephropathy].

    PubMed

    Mercadal, Lucile

    2013-12-01

    Membranous nephropathy is characterized by immune complex deposits on the outer side of the glomerular basement membrane. Activation of complement and of oxidation lead to basement membrane lesions. The most frequent form is idiopathic. At 5 and 10 years, renal survival is around 90 and 65% respectively. A prognostic model based on proteinuria, level and duration, progression of renal failure in a few months can refine prognosis. The urinary excretion of C5b-9, β2 and α1 microglobuline and IgG are strong predictors of outcome. Symptomatic treatment is based on anticoagulation in case of nephrotic syndrome, angiotensin conversion enzyme inhibitors, angiotensin II receptor blockers and statins. Immunosuppressive therapy should be discussed for patients having a high risk of progression. Corticoids alone has no indication. Treatment should include a simultaneous association or more often alternating corticoids and alkylant agent for a minimum of 6 months. Adrenocorticoid stimulating hormone and steroids plus mycophenolate mofetil may be equally effective. Steroids plus alkylant decrease the risk of end stage renal failure. Cyclosporine and tacrolimus decrease proteinuria but are associated with a high risk of recurrence at time of withdrawal and are nephrotoxic. Rituximab evaluated on open studies needs further evaluations to define its use. PMID:24315535

  7. How Membrane-Active Peptides Get into Lipid Membranes.

    PubMed

    Sani, Marc-Antoine; Separovic, Frances

    2016-06-21

    The structure-function relationship for a family of antimicrobial peptides (AMPs) from the skin of Australian tree frogs is discussed and compared with that of peptide toxins from bee and Australian scorpion venoms. Although these membrane-active peptides induce a similar cellular fate by disrupting the lipid bilayer integrity, their lytic activity is achieved via different modes of action, which are investigated in relation to amino acid sequence, secondary structure, and membrane lipid composition. In order to better understand what structural features govern the interaction between peptides and lipid membranes, cell-penetrating peptides (CPPs), which translocate through the membrane without compromising its integrity, are also discussed. AMPs possess membrane lytic activities that are naturally designed to target the cellular membrane of pathogens or competitors. They are extremely diverse in amino acid composition and often show specificity against a particular strain of microbe. Since our antibiotic arsenal is declining precariously in the face of the rise in multiantibiotic resistance, AMPs increasingly are seen as a promising alternative. In an effort to understand their molecular mechanism, biophysical studies of a myriad of AMPs have been reported, yet no unifying mechanism has emerged, rendering difficult the rational design of drug leads. Similarly, a wide variety of cytotoxic peptides are found in venoms, the best known being melittin, yet again, predicting their activity based on a particular amino acid composition or secondary structure remains elusive. A common feature of these membrane-active peptides is their preference for the lipid environment. Indeed, they are mainly unstructured in solution and, in the presence of lipid membranes, quickly adsorb onto the surface, change their secondary structure, eventually insert into the hydrophobic core of the membrane bilayer, and finally disrupt the bilayer integrity. These steps define the molecular

  8. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    In this project we intend to study a novel process concept, i.e, the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  9. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    In this project we intend to study a novel process concept, i.e.,the use of ceramic membranes reactors in upgrading of coal derived liquids. Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. They have, furthermore, the inherent capability for combining reaction and separation in a single step. Thus they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, as those typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we wig evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  10. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will also be investigated.

  11. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-06-19

    Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. In this project we will evaluate the performance of Sel-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. In addition, the development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  12. Characterization of a Membrane-active Peptide from the Bordetella pertussis CyaA Toxin*

    PubMed Central

    Subrini, Orso; Sotomayor-Pérez, Ana-Cristina; Hessel, Audrey; Spiaczka-Karst, Johanna; Selwa, Edithe; Sapay, Nicolas; Veneziano, Rémi; Pansieri, Jonathan; Chopineau, Joel; Ladant, Daniel; Chenal, Alexandre

    2013-01-01

    Bordetella pertussis, the pathogenic bacteria responsible for whooping cough, secretes several virulence factors, among which is the adenylate cyclase toxin (CyaA) that plays a crucial role in the early stages of human respiratory tract colonization. CyaA invades target cells by translocating its catalytic domain directly across the plasma membrane and overproduces cAMP, leading to cell death. The molecular process leading to the translocation of the catalytic domain remains largely unknown. We have previously shown that the catalytic domain per se, AC384, encompassing residues 1–384 of CyaA, did not interact with lipid bilayer, whereas a longer polypeptide, AC489, spanning residues 1–489, binds to membranes and permeabilizes vesicles. Moreover, deletion of residues 375–485 within CyaA abrogated the translocation of the catalytic domain into target cells. Here, we further identified within this region a peptidic segment that exhibits membrane interaction properties. A synthetic peptide, P454, corresponding to this sequence (residues 454–485 of CyaA) was characterized by various biophysical approaches. We found that P454 (i) binds to membranes containing anionic lipids, (ii) adopts an α-helical structure oriented in plane with respect to the lipid bilayer, and (iii) permeabilizes vesicles. We propose that the region encompassing the helix 454–485 of CyaA may insert into target cell membrane and induce a local destabilization of the lipid bilayer, thus favoring the translocation of the catalytic domain across the plasma membrane. PMID:24064217

  13. Cryogenic methane separation/catalytic hydrogasification process analysis. Quarterly report

    SciTech Connect

    Klosek, J.

    1980-12-02

    The objective of this extension of DOE contract No. DEAC01-78ET10325, Cryogenic Methane Separation/Catalytic Hydrogasification Process Analysis, is to perform trade-off and optimization studies for the Rockwell/Cities Service Short Residence Time Hydrogasification (SRTH) and the Exxon Catalytic Coal Gasification (CCG) processes in the acid gas removal and cryogenic separation areas. The contract extension is divided into nine (9) subtasks. Each subtask studies the effect of variation of a keV design parameter on the treatment cost of the SNG produced. All subtasks will be conducted under the Task I scope of the original DOE contract No. ET-78-C-01-3044, which includes block flow sheet, overall heat and material balance, utility summary, four-line equipment description, investment and treatment cost summaries and final report writing in addition to monthly and quarterly reports. Planning and progress by both companies is described briefly.

  14. The nature of hot electrons generated by exothermic catalytic reactions

    NASA Astrophysics Data System (ADS)

    Nedrygailov, Ievgen I.; Park, Jeong Young

    2016-02-01

    We review recent progress in studies of the nature of hot electrons generated in metal nanoparticles and thin films on oxide supports and their role in heterogeneous catalysis. We show that the creation of hot electrons and their transport across the metal-oxide interface is an inherent component of energy dissipation accompanying catalytic and photocatalytic surface reactions. The intensity of hot electron flow is well correlated with turnover rates of corresponding reactions. We also show that controlling the flow of hot electrons crossing the interface can lead to the control of chemical reaction rates. Finally, we discuss perspectives of hot-electron-mediated surface chemistry that promise the capability to drive catalytic reactions with enhanced efficiency and selectivity through electron-mediated, non-thermal processes.

  15. Shape control of multi-material heterostructures for catalytic applications

    NASA Astrophysics Data System (ADS)

    Habas, Susan Ellen

    epitaxial overgrowth of palladium to give shape-controlled core-shell type nanocrystals with structure-sensitive catalytic properties. Incorporation of a lattice-mismatched metal such as gold, on the other hand, introduces an element of selectivity leading to the growth of anisotropic binary nanocrystals where both metals are exposed. The development of multi-component nanoparticles represents a new approach for creating smart materials, requiring controlled and selective growth of different materials on a single particle. In the final section, the concept of seeded overgrowth has been extended to include semiconductor nanostructures as seeds, introducing even greater potential for selective overgrowth of metals due to the unique chemical composition of the different crystallographic facets. Platinum and related binary metals were grown with high selectivity on the tips of cadmium sulfide nanorods for catalytic and energy applications.

  16. Lipid membranes for membrane proteins.

    PubMed

    Kukol, Andreas

    2015-01-01

    The molecular dynamics (MD) simulation of membrane proteins requires the setup of an accurate representation of lipid bilayers. This chapter describes the setup of a lipid bilayer system from scratch using generally available tools, starting with a definition of the lipid molecule POPE, generation of a lipid bilayer, energy minimization, MD simulation, and data analysis. The data analysis includes the calculation of area and volume per lipid, deuterium order parameters, self-diffusion constant, and the electron density profile. PMID:25330959

  17. Hydrogen Permeability of Palladium Membrane for Steam-Reforming of Bio-Ethanol Using the Membrane Reactor

    NASA Astrophysics Data System (ADS)

    Kinouchi, Kouji; Katoh, Masahiro; Horikawa, Toshihide; Yoshikawa, Takushi; Wada, Mamoru

    A Palladium membrane was prepared by electro-less plating method on porous stainless steel. The catalytic hydrogen production by steam-reforming of biomass-derived ethanol (bio-ethanol) using a Pd membrane was analyzed by comparing it with those for the reaction using reagent ethanol (the reference sample). And the hydrogen permeability of the palladium membrane was investigated using the same palladium membrane (H2/He selectivity = 249, at ΔP = 0.10 MPa, 873 K). As a result, for bio-ethanol, deposited carbon had a negative influence on the hydrogen-permeability of the palladium membrane and hydrogen purity. The sulfur content in the bio-ethanol may have promoted carbon deposition. By using a palladium membrane, it was confirmed that H2 yield (%) was increased. It can be attributed that methane was converted from ethanol and produced more hydrogen by steam reforming, due to the in situ removal of hydrogen from the reaction location.

  18. Omniphobic Membrane for Robust Membrane Distillation

    SciTech Connect

    Lin, SH; Nejati, S; Boo, C; Hu, YX; Osuji, CO; Ehmelech, M

    2014-11-01

    In this work, we fabricate an omniphobic microporous membrane for membrane distillation (MD) by modifying a hydrophilic glass fiber membrane with silica nanoparticles followed by surface fluorination and polymer coating. The modified glass fiber membrane exhibits an anti-wetting property not only against water but also against low surface tension organic solvents that easily wet a hydrophobic polytetrafluoroethylene (PTFE) membrane that is commonly used in MD applications. By comparing the performance of the PTFE and omniphobic membranes in direct contact MD experiments in the presence of a surfactant (sodium dodecyl sulfate, SDS), we show that SDS wets the hydrophobic PTFE membrane but not the omniphobic membrane. Our results suggest that omniphobic membranes are critical for MD applications with feed waters containing surface active species, such as oil and gas produced water, to prevent membrane pore wetting.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. Modulated mechanism of phosphatidylserine on the catalytic activity of Naja naja atra phospholipase A2 and Notechis scutatus scutatus notexin.

    PubMed

    Chiou, Yi-Ling; Lin, Shinne-Ren; Hu, Wan-Ping; Chang, Long-Sen

    2014-12-15

    Phosphatidylserine (PS) externalization is a hallmark for apoptotic death of cells. Previous studies showed that Naja naja atra phospholipase A2 (NnaPLA2) and Notechis scutatus scutatus notexin induced apoptosis of human cancer cells. However, NnaPLA2 and notexin did not markedly disrupt the integrity of cellular membrane as evidenced by membrane permeability of propidium iodide. These findings reflected that the ability of NnaPLA2 and notexin to hydrolyze membrane phospholipids may be affected by PS externalization. To address that question, this study investigated the membrane-interacted mode and catalytic activity of NnaPLA2 and notexin toward outer leaflet (phosphatidylcholine/sphingomyelin/cholesterol, PC/SM/Chol) and inner leaflet (phosphatidylserine/phosphatidylethanolamine/cholesterol, PS/PE/Chol) of plasma membrane-mimicking vesicles. PS incorporation promoted enzymatic activity of NnaPLA2 and notexin on PC and PC/SM vesicles, but suppressed NnaPLA2 and notexin activity on PC/SM/Chol and PE/Chol vesicles. PS incorporation increased the membrane fluidity of PC vesicles but reduced membrane fluidity of PC/SM, PC/SM/Chol and PE/Chol vesicles. PS increased the phospholipid order of all the tested vesicles. Moreover, PS incorporation did not greatly alter the binding affinity of notexin and NnaPLA2 with phospholipid vesicles. Acrylamide quenching studies and trinitrophenylation of Lys residues revealed that membrane-bound mode of notexin and NnaPLA2 varied with the targeted membrane compositions. The fine structure of catalytic site in NnaPLA2 and notexin in all the tested vesicles showed different changes. Collectively, the present data suggest that membrane-inserted PS modulates PLA2 interfacial activity via its effects on membrane structure and membrane-bound mode of NnaPLA2 and notexin, and membrane compositions determine the effect of PS on PLA2 activity. PMID:25449100

  4. Thin membranes of new hard/soft segment copolymers

    SciTech Connect

    Ho, W.S.; Sartori, G.; Thaler, W.A.

    1996-12-31

    Thin membranes of new hard/soft segment copolymers have been synthesized for the separation of aromatics from saturates through high temperature pervaporation. In the membranes, hard segments provide temperature stability and solvent resistance, while soft segments govern aromatic/saturate selectivity and flux. We have synthesized new chlorinated polyurethane/polyester and polyimide/polyester copolymers. Based on a polyimide copolymer membrane, a new technology has been developed recently to separate heavy catalytically cracked naphtha into an aromatics-rich permeate and an aromatics-lean retentate.

  5. Membrane Assembly Driven by a Biomimetic Coupling Reaction

    PubMed Central

    Budin, Itay; Devaraj, Neal K.

    2012-01-01

    One of the major goals of synthetic biology is the development of non-natural cellular systems. In this work we describe a catalytic biomimetic coupling reaction capable of driving the de novo self-assembly of phospholipid membranes. Our system features a copper catalyzed azide-alkyne cycloaddition that results in the formation of a triazole containing phospholipid analog. Concomitant assembly of membranes occurs spontaneously, not requiring preexisting membranes to house catalysts or precursors. The substitution of efficient synthetic reactions for key biochemical processes may offer a general route toward synthetic biological systems. PMID:22239722

  6. 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...

  7. Polymer nanocomposite membranes with hierarchically structured catalysts for high throughput dehalogenation

    NASA Astrophysics Data System (ADS)

    Crock, Christopher A.

    Halogenated organics are categorized as primary pollutants by the Environmental Protection Agency. Trichloroethylene (TCE), which had broad industrial use in the past, shows persistence in the environment because of its chemical stability. The large scale use and poor control of TCE resulted in its prolonged release into the environment before the carcinogenic risk associated with TCE was fully understood. TCE pollution stemmed from industrial effluents and improper disposal of solvent waste. Membrane reactors are promising technology for treating TCE polluted groundwater because of the high throughput, relatively low cost of membrane fabrication and facile retrofitting of existing membrane based water treatment facilities with catalytic membrane reactors. Compared to catalytic fluidized or fixed bed reactors, catalytic membrane reactors feature minimal diffusional limitation. Additionally, embedding catalyst within the membrane avoids the need for catalyst recovery and can prevent aggregation of catalytic nanoparticles. In this work, Pd/xGnP, Pd-Au/xGnP, and commercial Pd/Al2O3 nanoparticles were employed in batch and flow-through membrane reactors to catalyze the dehalogenation of TCE in the presence of dissolved H2. Bimetallic Pd-Au/xGnP catalysts were shown to be more active than monometallic Pd/xGnP or commercial Pd/Al 2O3 catalysts. In addition to synthesizing nanocomposite membranes for high-throughput TCE dehalogenation, the membrane based dehalogenation process was designed to minimize the detrimental impact of common catalyst poisons (S2-, HS-, and H2S -) by concurrent oxidation of sulfide species to gypsum in the presence of Ca2+ and removal of gypsum through membrane filtration. The engineered membrane dehalogenation process demonstrated that bimetallic Pd-Au/xGnP catalysts resisted deactivation by residual sulfide species after oxidation, and showed complete removal of gypsum during membrane filtration.

  8. Efficient preparation and analysis of membrane and membrane protein systems.

    PubMed

    Javanainen, Matti; Martinez-Seara, Hector

    2016-10-01

    Molecular dynamics (MD) simulations have become a highly important technique to consider lipid membrane systems, and quite often they provide considerable added value to laboratory experiments. Rapid development of both software and hardware has enabled the increase of time and size scales reachable by MD simulations to match those attainable by several accurate experimental techniques. However, until recently, the quality and maturity of software tools available for building membrane models for simulations as well as analyzing the results of these simulations have seriously lagged behind. Here, we discuss the recent developments of such tools from the end-users' point of view. In particular, we review the software that can be employed to build lipid bilayers and other related structures with or without embedded membrane proteins to be employed in MD simulations. Additionally, we provide a brief critical insight into force fields and MD packages commonly used for membrane and membrane protein simulations. Finally, we list analysis tools that can be used to study the properties of membrane and membrane protein systems. In all these points we comment on the respective compatibility of the covered tools. We also share our opinion on the current state of the available software. We briefly discuss the most commonly employed tools and platforms on which new software can be built. We conclude the review by providing a few ideas and guidelines on how the development of tools can be further boosted to catch up with the rapid pace at which the field of membrane simulation progresses. This includes improving the compatibility between software tools and promoting the openness of the codes on which these applications rely. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26947184

  9. Membrane patterned by pulsed laser micromachining for proton exchange membrane fuel cell with sputtered ultra-low catalyst loadings

    NASA Astrophysics Data System (ADS)

    Cuynet, S.; Caillard, A.; Kaya-Boussougou, S.; Lecas, T.; Semmar, N.; Bigarré, J.; Buvat, P.; Brault, P.

    2015-12-01

    Proton exchange membranes were nano- and micro-patterned on their cathode side by pressing them against stainless steel molds previously irradiated by a Ti:Sapphire femtosecond laser. The membranes were associated to ultra-low loaded thin catalytic layers (25 μgPt cm-2) prepared by plasma magnetron sputtering. The Pt catalyst was sputtered either on the membrane or on the porous electrode. The fuel cell performance in dry conditions were found to be highly dependent on the morphology of the membrane surface. When nanometric ripples covered by a Pt catalyst were introduced on the surface of the membrane, the fuel cell outperformed the conventional one with a flat membrane. By combining nano- and micro-patterns (nanometric ripples and 11-24 μm deep craters), the performance of the cells was clearly enhanced. The maximum power density achieved by the fuel cell was multiplied by a factor of 3.6 (at 50 °C and 3 bar): 438 mW cm-2 vs 122 mW cm-2. This improvement is due to high catalyst utilization with a high membrane conductivity. When Pt is sputtered on the porous electrode (and not on the membrane), the contribution of the patterned membrane to the fuel cell efficiency was less significant, except in the presence of nanometric ripples. This result suggests that the patterning of the membrane must be consistent with the way the catalyst is synthesized, on the membrane or on the porous electrode.

  10. 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).

  11. 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

  12. Advanced membrane electrode assemblies for fuel cells

    DOEpatents

    Kim, Yu Seung; Pivovar, Bryan S.

    2012-07-24

    A method of preparing advanced membrane electrode assemblies (MEA) for use in fuel cells. A base polymer is selected for a base membrane. An electrode composition is selected to optimize properties exhibited by the membrane electrode assembly based on the selection of the base polymer. A property-tuning coating layer composition is selected based on compatibility with the base polymer and the electrode composition. A solvent is selected based on the interaction of the solvent with the base polymer and the property-tuning coating layer composition. The MEA is assembled by preparing the base membrane and then applying the property-tuning coating layer to form a composite membrane. Finally, a catalyst is applied to the composite membrane.

  13. Advanced membrane electrode assemblies for fuel cells

    SciTech Connect

    Kim, Yu Seung; Pivovar, Bryan S

    2014-02-25

    A method of preparing advanced membrane electrode assemblies (MEA) for use in fuel cells. A base polymer is selected for a base membrane. An electrode composition is selected to optimize properties exhibited by the membrane electrode assembly based on the selection of the base polymer. A property-tuning coating layer composition is selected based on compatibility with the base polymer and the electrode composition. A solvent is selected based on the interaction of the solvent with the base polymer and the property-tuning coating layer composition. The MEA is assembled by preparing the base membrane and then applying the property-tuning coating layer to form a composite membrane. Finally, a catalyst is applied to the composite membrane.

  14. Reactive nanostructured membranes for water purification.

    PubMed

    Lewis, Scott R; Datta, Saurav; Gui, Minghui; Coker, Eric L; Huggins, Frank E; Daunert, Sylvia; Bachas, Leonidas; Bhattacharyya, Dibakar

    2011-05-24

    Many current treatments for the reclamation of contaminated water sources are chemical-intensive, energy-intensive, and/or require posttreatment due to unwanted by-product formation. We demonstrate that through the integration of nanostructured materials, enzymatic catalysis, and iron-catalyzed free radical reactions within pore-functionalized synthetic membrane platforms, we are able to conduct environmentally important oxidative reactions for toxic organic degradation and detoxification from water without the addition of expensive or harmful chemicals. In contrast to conventional, passive membrane technologies, our approach utilizes two independently controlled, nanostructured membranes in a stacked configuration for the generation of the necessary oxidants. These include biocatalytic and organic/inorganic (polymer/iron) nanocomposite membranes. The bioactive (top) membrane contains an electrostatically immobilized enzyme for the catalytic production of one of the main reactants, hydrogen peroxide (H(2)O(2)), from glucose. The bottom membrane contains either immobilized iron ions or ferrihydrite/iron oxide nanoparticles for the decomposition of hydrogen peroxide to form powerful free radical oxidants. By permeating (at low pressure) a solution containing a model organic contaminant, such as trichlorophenol, with glucose in oxygen-saturated water through the membrane stack, significant contaminant degradation was realized. To illustrate the effectiveness of this membrane platform in real-world applications, membrane-immobilized ferrihydrite/iron oxide nanoparticles were reacted with hydrogen peroxide to form free radicals for the degradation of a chlorinated organic contaminant in actual groundwater. Although we establish the development of these nanostructured materials for environmental applications, the practical and methodological advances demonstrated here permit the extension of their use to applications including disinfection and/or virus inactivation. PMID

  15. Reactive nanostructured membranes for water purification

    PubMed Central

    Lewis, Scott R.; Datta, Saurav; Gui, Minghui; Coker, Eric L.; Huggins, Frank E.; Daunert, Sylvia; Bachas, Leonidas; Bhattacharyya, Dibakar

    2011-01-01

    Many current treatments for the reclamation of contaminated water sources are chemical-intensive, energy-intensive, and/or require posttreatment due to unwanted by-product formation. We demonstrate that through the integration of nanostructured materials, enzymatic catalysis, and iron-catalyzed free radical reactions within pore-functionalized synthetic membrane platforms, we are able to conduct environmentally important oxidative reactions for toxic organic degradation and detoxification from water without the addition of expensive or harmful chemicals. In contrast to conventional, passive membrane technologies, our approach utilizes two independently controlled, nanostructured membranes in a stacked configuration for the generation of the necessary oxidants. These include biocatalytic and organic/inorganic (polymer/iron) nanocomposite membranes. The bioactive (top) membrane contains an electrostatically immobilized enzyme for the catalytic production of one of the main reactants, hydrogen peroxide (H2O2), from glucose. The bottom membrane contains either immobilized iron ions or ferrihydrite/iron oxide nanoparticles for the decomposition of hydrogen peroxide to form powerful free radical oxidants. By permeating (at low pressure) a solution containing a model organic contaminant, such as trichlorophenol, with glucose in oxygen-saturated water through the membrane stack, significant contaminant degradation was realized. To illustrate the effectiveness of this membrane platform in real-world applications, membrane-immobilized ferrihydrite/iron oxide nanoparticles were reacted with hydrogen peroxide to form free radicals for the degradation of a chlorinated organic contaminant in actual groundwater. Although we establish the development of these nanostructured materials for environmental applications, the practical and methodological advances demonstrated here permit the extension of their use to applications including disinfection and/or virus inactivation. PMID

  16. Entropy production of a steady-growth cell with catalytic reactions

    NASA Astrophysics Data System (ADS)

    Himeoka, Yusuke; Kaneko, Kunihiko

    2014-10-01

    Cells generally convert external nutrient resources to support metabolism and growth. Understanding the thermodynamic efficiency of this conversion is essential to determine the general characteristics of cellular growth. Using a simple protocell model with catalytic reaction dynamics to synthesize the necessary enzyme and membrane components from nutrients, the entropy production per unit-cell-volume growth is calculated analytically and numerically based on the rate equation for chemical kinetics and linear nonequilibrium thermodynamics. The minimal entropy production per unit-cell growth is found to be achieved at a nonzero nutrient uptake rate rather than at a quasistatic limit as in the standard Carnot engine. This difference appears because the equilibration mediated by the enzyme exists only within cells that grow through enzyme and membrane synthesis. Optimal nutrient uptake is also confirmed by protocell models with many chemical components synthesized through a catalytic reaction network. The possible relevance of the identified optimal uptake to optimal yield for cellular growth is also discussed.

  17. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T.

    1992-01-01

    Membrane reactors have been used in a number of catalytic reaction processes in order to overcome the limitations on conversion imposed by thermodynamic equilibrium. Having the inherent capability for combining reaction and separation in a single step, they offer promise for improving and optimizing yield, selectivity and performance of processes involving complex liquids, such as these typically found in coal liquid upgrading. Ceramic membranes are a new class of materials, which have shown promise in a variety of industrial applications. Their mechanical and chemical stability coupled with a wide range of operating temperatures and pressures make them suitable for environments found in coal liquid upgrading. This project will evaluate the performance of Sol-Gel alumina membranes in coal liquid upgrading processes under realistic temperature and pressure conditions and investigate the feasibility of using such membranes in a membrane reactor based coal liquid upgrading process. Development of novel ceramic membranes with enhanced catalytic activity for coal-liquid upgrading applications, such as carbon-coated alumina membranes, will be also investigated.

  18. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

    Hodgdon, R. B.; Waite, W. A.

    1980-01-01

    The efforts on the synthesis of polymer anion redox membranes were mainly concentrated in two areas, membrane development and membrane fabrication. Membrane development covered the preparation and evaluation of experimental membranes systems with improved resistance stability and/or lower permeability. Membrane fabrication covered the laboratory scale production of prime candidate membranes in quantities of up to two hundred and sizes up to 18 inches x 18 inches (46 cm x 46 cm). These small (10 in x 11 in) and medium sized membranes were mainly for assembly into multicell units. Improvements in processing procedures and techniques for preparing such membrane sets lifted yields to over 90 percent.

  19. A Structural Study of CESA1 Catalytic Domain of Arabidopsis Cellulose Synthesis Complex: Evidence for CESA Trimers

    SciTech Connect

    Vandavasi, Venu Gopal; Putnam, Daniel K.; Zhang, Qiu; Petridis, Loukas; Heller, William T.; Nixon, B. Tracy; Haigler, Candace H.; Kalluri, Udaya; Coates, Leighton; Langan, Paul; Smith, Jeremy C.; Meiler, Jens; O’Neill, Hugh

    2015-11-10

    In a cellulose synthesis complex a "rosette" shape is responsible for the synthesis of cellulose chains and their assembly into microfibrils within the cell walls of land plants and their charophyte algal progenitors. The number of cellulose synthase proteins in this large multisubunit transmembrane protein complex and the number of cellulose chains in a microfibril have been debated for many years. Our work reports a low resolution structure of the catalytic domain of CESA1 from Arabidopsis (Arabidopsis thaliana; AtCESA1CatD) determined by small-angle scattering techniques and provides the first experimental evidence for the self-assembly of CESA into a stable trimer in solution. The catalytic domain was overexpressed in Escherichia coli, and using a two-step procedure, it was possible to isolate monomeric and trimeric forms of AtCESA1CatD. Moreover, the conformation of monomeric and trimeric AtCESA1CatD proteins were studied using small-angle neutron scattering and small-angle x-ray scattering. A series of AtCESA1CatD trimer computational models were compared with the small-angle x-ray scattering trimer profile to explore the possible arrangement of the monomers in the trimers. Several candidate trimers were identified with monomers oriented such that the newly synthesized cellulose chains project toward the cell membrane. In these models, the class-specific region is found at the periphery of the complex, and the plant-conserved region forms the base of the trimer. Finally, this study strongly supports the "hexamer of trimers" model for the rosette cellulose synthesis complex that synthesizes an 18-chain cellulose microfibril as its fundamental product.

  20. A Structural Study of CESA1 Catalytic Domain of Arabidopsis Cellulose Synthesis Complex: Evidence for CESA Trimers

    DOE PAGESBeta

    Vandavasi, Venu Gopal; Putnam, Daniel K.; Zhang, Qiu; Petridis, Loukas; Heller, William T.; Nixon, B. Tracy; Haigler, Candace H.; Kalluri, Udaya; Coates, Leighton; Langan, Paul; et al

    2015-11-10

    In a cellulose synthesis complex a "rosette" shape is responsible for the synthesis of cellulose chains and their assembly into microfibrils within the cell walls of land plants and their charophyte algal progenitors. The number of cellulose synthase proteins in this large multisubunit transmembrane protein complex and the number of cellulose chains in a microfibril have been debated for many years. Our work reports a low resolution structure of the catalytic domain of CESA1 from Arabidopsis (Arabidopsis thaliana; AtCESA1CatD) determined by small-angle scattering techniques and provides the first experimental evidence for the self-assembly of CESA into a stable trimer inmore » solution. The catalytic domain was overexpressed in Escherichia coli, and using a two-step procedure, it was possible to isolate monomeric and trimeric forms of AtCESA1CatD. Moreover, the conformation of monomeric and trimeric AtCESA1CatD proteins were studied using small-angle neutron scattering and small-angle x-ray scattering. A series of AtCESA1CatD trimer computational models were compared with the small-angle x-ray scattering trimer profile to explore the possible arrangement of the monomers in the trimers. Several candidate trimers were identified with monomers oriented such that the newly synthesized cellulose chains project toward the cell membrane. In these models, the class-specific region is found at the periphery of the complex, and the plant-conserved region forms the base of the trimer. Finally, this study strongly supports the "hexamer of trimers" model for the rosette cellulose synthesis complex that synthesizes an 18-chain cellulose microfibril as its fundamental product.« less

  1. Live cell imaging of membrane / cytoskeleton interactions and membrane topology

    NASA Astrophysics Data System (ADS)

    Chierico, Luca; Joseph, Adrian S.; Lewis, Andrew L.; Battaglia, Giuseppe

    2014-09-01

    We elucidate the interaction between actin and specific membrane components, using real time live cell imaging, by delivering probes that enable access to components, that cannot be accessed genetically. We initially investigated the close interplay between Phosphatidylinositol 4,5-bisphosphate (PIP2) and the F-actin network. We show that, during the early stage of cell adhesion, PIP2 forms domains within the filopodia membrane. We studied these domains alongside cell spreading and observed that these very closely follow the actin tread-milling. We show that this mechanism is associated with an active transport of PIP2 rich organelles from the cell perinuclear area to the edge, along actin fibers. Finally, mapping other phospholipids and membrane components we observed that the PIP2 domains formation is correlated with sphingosine and cholesterol rafts.

  2. Tissue printing on nitrocellulose membrane

    SciTech Connect

    Taylor, R.; Song, Yanru; Pont-Lezica, R.; Lin, Liangshiou; Ye, Zhenghua; Varner, J.E. )

    1989-04-01

    In the 1950's Daoust developed substrate film printing on gelatin and starch films to localize protease, amylase, DNAase and RNAase activities. These procedures were adapted to plant tissues by Yomo and Taylor (1973) and by Jacobsen and Knox (1973). Membranes such as nitrocellulose bind cellular materials from cut tissue surfaces with little lateral diffusion. Thus accurate chemical prints are obtained. When the tissue is pressed firmly onto nitrocellulose a physical impression is obtained which shows the anatomy of the tissue. We have used the tissue-print technique to localize (1) proteins with labeled antibodies, (2) RNA with labeled nucleic acid probes, (3) enzymes by catalytic activity, (4) glycoproteins by fluorescent lectins, (5) lectins by fluorescent sugars, (6) cysteine-rich proteins by dansylated iodoacetamide, (7) ascorbic acid by silver nitrate, (8) soluble fluorescent compounds by direct observation.

  3. Selecting a Roof Membrane.

    ERIC Educational Resources Information Center

    Waldron, Larry W.

    1990-01-01

    Offers a brief synopsis of the unique characteristics of the following roof membranes: (1) built-up roofing; (2) elastoplastic membranes; (3) modified bitumen membranes; (4) liquid applied membranes; and (5) metal roofing. A chart compares the characteristics of the raw membranes only. (MLF)

  4. Magnetic Membrane System

    DOEpatents

    McElfresh, Michael W.; ; Lucas, Matthew S.

    2004-12-30

    The present invention provides a membrane with magnetic particles. In one embodiment the membrane is created by mixing particles in a non-magnetic base. The membrane may act as an actuator, a sensor, a pump, a valve, or other device. A magnet is operatively connected to the membrane. The magnet acts on and changes the shape of the membrane.

  5. Silica nanoporous membranes and their applications

    NASA Astrophysics Data System (ADS)

    Khabibullin, Amir

    This thesis describes the development of novel silica and hybrid nanoporous membranes. Nanoporous membranes are widely used in various applications. This thesis focuses on their potential applications in the energy area, such as fuel cells and lithium batteries, and in separations and ultrafiltration. We use silica colloidal spheres and polymer-modified silica spheres to prepare the membranes in a time-, cost- and material-efficient manner. First, we prepared novel silica nanoporous membranes by pressing silica colloidal spheres followed by sintering. The pore size, the thickness, and the area of the membrane are precisely controlled by experiment parameters. The resulting membranes are mechanically and thermally durable, crack-free, and capable of size-selective transport. Next, to demonstrate the utility of the pressed membranes, described above, the proton-conductive pore-filled silica colloidal membranes were prepared and the fuel cells were constructed using these membranes. We modified these membranes by filling the membrane pores with surface-attached proton-conductive polymer brushes and prepared membrane-electrode assemblies to test fuel cell performance. We studied the proton conductivity and fuel cell performance as a function of the amount of sulfonic groups in the membrane. We also prepared and characterized reversible hybrid nanoporous membranes, self-assembled from solution containing polymer-modified silica colloidal spheres. Here we applied the new concept of noncovalent membranes, where the material is held together via noncovalent interactions of polymer brushes. This enables so-called reversible assembly of the membranes, in which membrane can be assembled in one solvent and dissolved in other. This approach provides advantages in recycling and reusing of the material. This work is one of the first of its kind and it opens a whole new area of research on reversible membranes made of polymer-modified nanoparticles. Finally, we applied our

  6. Effect of hierarchical porosity and phosphorus modification on the catalytic properties of zeolite Y

    NASA Astrophysics Data System (ADS)

    Li, Wenlin; Zheng, Jinyu; Luo, Yibin; Da, Zhijian

    2016-09-01

    The zeolite Y is considered as a leading catalyst for FCC industry. The acidity and porosity modification play important roles in determining the final catalytic properties of zeolite Y. The alkaline treatment of zeolite Y by dealumination and alkaline treatment with NaOH and NaOH&TBPH was investigated. The zeolites were characterized by X-ray diffraction, low-temperature adsorption of nitrogen, transmission electron microscope, NMR, NH3-TPD and IR study of acidity. Accordingly, the hierarchical porosity and acidity property were discussed systematically. Finally, the catalytic performance of the zeolites Y was evaluated in the cracking of 1,3,5-TIPB. It was found that desilication with NaOH&TBPH ensured the more uniform intracrystalline mesoporosity with higher microporosity, while preserving higher B/L ratio and moderate Brønsted acidities resulting in catalysts with the most appropriated acidity and then with better catalytic performance.

  7. Final Report of a CRADA Between Pacific Northwest National Laboratory and the Ford Motor Company (CRADA No. PNNL/265): “Deactivation Mechanisms of Base Metal/Zeolite Urea Selective Catalytic Reduction Materials, and Development of Zeolite-Based Hydrocarbon Adsorber Materials”

    SciTech Connect

    Gao, Feng; Kwak, Ja Hun; Lee, Jong H.; Tran, Diana N.; Peden, Charles HF; Howden, Ken; Cheng, Yisun; Lupescu, Jason; Cavattaio, Giovanni; Lambert, Christine; McCabe, Robert W.

    2013-02-14

    the engine exhaust. For these reasons, automakers and engine manufacturers have difficulty improving their catalytic converters for meeting the stringent HC emission standards. In this collaborative program, scientists and engineers in the Institute for Integrated Catalysis at Pacific Northwest National Laboratory and at Ford Motor Company have investigated laboratory- and engine-aged SCR catalysts, containing mainly base metal zeolites. These studies are leading to a better understanding of various aging factors that impact the long-term performance of SCR catalysts and improve the correlation between laboratory and engine aging, saving experimental time and cost. We have also studied materials effective for the temporary storage of HC species during the cold-start period. In particular, we have examined the adsorption and desorption of various HC species produced during the combustion with different fuels (e.g., gasoline, E85, diesel) over potential HC adsorber materials, and measured the kinetic parameters to update Ford’s HC adsorption model. Since this CRADA has now been completed, in this final report we will provide brief summaries of most of the work carried out on this CRADA over the last several years.

  8. 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.

  9. 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...

  10. Multilayered Magnetic Gelatin Membrane Scaffolds.

    PubMed

    Samal, Sangram K; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

    2015-10-21

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial-magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Silver nanocluster catalytic microreactors for water purification

    NASA Astrophysics Data System (ADS)

    Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

    2016-07-01

    A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

  17. Sampling the membrane: function of rhomboid-family proteins.

    PubMed

    Lemberg, Marius K

    2013-05-01

    Rhomboids constitute a conserved protein superfamily that specifically binds membrane proteins and directs them into various different cellular pathways ranging from regulated secretion to endoplasmic reticulum (ER)-associated degradation (ERAD). Rhomboid proteases are known to release protein domains from membranes by a cut in their membrane anchor, whereas an emerging new class of rhomboid-family proteins lacks key catalytic residues and is not proteolytically active. Recent work has shown that these rhomboid pseudoproteases, including iRhoms and derlins, bind membrane proteins to regulate their fate, but the underlying molecular mechanism is not known. This review summarizes recent advances in the molecular understanding of rhomboid-family proteins and discusses common principles in how they recognize and bind proteins in the plane of the membrane. PMID:23369641

  18. Catalytic reactor with improved burner

    DOEpatents

    Faitani, Joseph J.; Austin, George W.; Chase, Terry J.; Suljak, George T.; Misage, Robert J.

    1981-01-01

    To more uniformly distribute heat to the plurality of catalyst tubes in a catalytic reaction furnace, the burner disposed in the furnace above the tops of the tubes includes concentric primary and secondary annular fuel and air outlets. The fuel-air mixture from the primary outlet is directed towards the tubes adjacent the furnace wall, and the burning secondary fuel-air mixture is directed horizontally from the secondary outlet and a portion thereof is deflected downwardly by a slotted baffle toward the tubes in the center of the furnace while the remaining portion passes through the slotted baffle to another baffle disposed radially outwardly therefrom which deflects it downwardly in the vicinity of the tubes between those in the center and those near the wall of the furnace.

  19. Catalytic, enantioselective, vinylogous aldol reactions.

    PubMed

    Denmark, Scott E; Heemstra, John R; Beutner, Gregory L

    2005-07-25

    In 1935, R. C. Fuson formulated the principle of vinylogy to explain how the influence of a functional group may be felt at a distant point in the molecule when this position is connected by conjugated double-bond linkages to the group. In polar reactions, this concept allows the extension of the electrophilic or nucleophilic character of a functional group through the pi system of a carbon-carbon double bond. This vinylogous extension has been applied to the aldol reaction by employing "extended" dienol ethers derived from gamma-enolizable alpha,beta-unsaturated carbonyl compounds. Since 1994, several methods for the catalytic, enantioselective, vinylogous aldol reaction have appeared, with which varying degrees of regio- (site), enantio-, and diastereoselectivity can be attained. In this Review, the current scope and limitations of this transformation, as well as its application in natural product synthesis, are discussed. PMID:15940727

  20. Electrochemical promotion of catalytic reactions

    NASA Astrophysics Data System (ADS)

    Imbihl, R.

    2010-05-01

    The electrochemical promotion of heterogeneously catalyzed reactions (EPOC) became feasible through the use of porous metal electrodes interfaced to a solid electrolyte. With the O 2- conducting yttrium stabilized zirconia (YSZ), the Na + conducting β″-Al 2O 3 (β-alumina), and several other types of solid electrolytes the EPOC effect has been demonstrated for about 100 reaction systems in studies conducted mainly in the mbar range. Surface science investigations showed that the physical basis for the EPOC effect lies in the electrochemically induced spillover of oxygen and alkali metal, respectively, onto the surface of the metal electrodes. For the catalytic promotion effect general concepts and mechanistic schemes were proposed but these concepts and schemes are largely speculative. Applying surface analytical tools to EPOC systems the proposed mechanistic schemes can be verified or invalidated. This report summarizes the progress which has been achieved in the mechanistic understanding of the EPOC effect.

  1. Catalytic decarbonylation of biosourced substrates.

    PubMed

    Ternel, Jérémy; Lebarbé, Thomas; Monflier, Eric; Hapiot, Frédéric

    2015-05-11

    Linear α-olefins (LAO) are one of the main targets in the field of surfactants, lubricants, and polymers. With the depletion of petroleum resources, the production of LAO from renewable feedstocks has gained increasing interest in recent years. In the present study, we demonstrated that Ir catalysts were suitable to decarbonylate a wide range of biosourced substrates under rather mild conditions (160 °C, 5 h reaction time) in the presence of potassium iodide and acetic anhydride. The resulting LAO were obtained with good conversion and selectivity provided that the purity of the substrate, the nature of the ligand, and the amounts of the additives were controlled accurately. The catalytic system could be recovered efficiently by using a Kugelrohr distillation apparatus and recycled. PMID:25855489

  2. APPARATUS FOR CATALYTICALLY COMBINING GASES

    DOEpatents

    Busey, H.M.

    1958-08-12

    A convection type recombiner is described for catalytically recombining hydrogen and oxygen which have been radiolytically decomposed in an aqueous homogeneous nuclear reactor. The device is so designed that the energy of recombination is used to circulate the gas mixture over the catalyst. The device consists of a vertical cylinder having baffles at its lower enda above these coarse screens having platinum and alumina pellets cemented thereon, and an annular passage for the return of recombined, condensed water to the reactor moderator system. This devicea having no moving parts, provides a simple and efficient means of removing the danger of accumulated hot radioactive, explosive gases, and restoring them to the moderator system for reuse.

  3. 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.

  4. 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.

  5. Membrane Systems in Cyanobacteria

    SciTech Connect

    Liberton, Michelle L.; Pakrasi, Himadri B.

    2008-01-01

    Cyanobacteria are photosynthetic prokaryotes with highly differentiated membrane systems. In addition to a Gram-negative-type cell envelope with plasma membrane and outer membrane separated by a periplasmic space, cyanobacteria have an internal system of thylakoid membranes where the fully functional electron transfer chains of photosynthesis and respiration reside. The presence of different membrane systems lends these cells a unique complexity among bacteria. Cyanobacteria must be able to reorganize the membranes, synthesize new membrane lipids, and properly target proteins to the correct membrane system. The outer membrane, plasma membrane, and thylakoid membranes each have specialized roles in the cyanobacterial cell. Understanding the organization, functionality, protein composition and dynamics of the membrane systems remains a great challenge in cyanobacterial cell biology.

  6. Induced fit and the catalytic mechanism of isocitrate dehydrogenase.

    PubMed

    Gonçalves, Susana; Miller, Stephen P; Carrondo, Maria A; Dean, Anthony M; Matias, Pedro M

    2012-09-11

    NADP(+) dependent isocitrate dehydrogenase (IDH; EC 1.1.1.42) belongs to a large family of α-hydroxyacid oxidative β-decarboxylases that catalyze similar three-step reactions, with dehydrogenation to an oxaloacid intermediate preceding β-decarboxylation to an enol intermediate followed by tautomerization to the final α-ketone product. A comprehensive view of the induced fit needed for catalysis is revealed on comparing the first "fully closed" crystal structures of a pseudo-Michaelis complex of wild-type Escherichia coli IDH (EcoIDH) and the "fully closed" reaction product complex of the K100M mutant with previously obtained "quasi-closed" and "open" conformations. Conserved catalytic residues, binding the nicotinamide ring of NADP(+) and the metal-bound substrate, move as rigid bodies during domain closure by a hinge motion that spans the central β-sheet in each monomer. Interactions established between Thr105 and Ser113, which flank the "phosphorylation loop", and the nicotinamide mononucleotide moiety of NADP(+) establish productive coenzyme binding. Electrostatic interactions of a Lys100-Leu103-Asn115-Glu336 tetrad play a pivotal role in assembling a catalytically competent active site. As predicted, Lys230* is positioned to deprotonate/reprotonate the α-hydroxyl in both reaction steps and Tyr160 moves into position to protonate C3 following β-decarboxylation. A proton relay from the catalytic triad Tyr160-Asp307-Lys230* connects the α-hydroxyl of isocitrate to the bulk solvent to complete the picture of the catalytic mechanism. PMID:22891681

  7. Catalytic Iodination of the Aliphatic C-F Bond by YbI3(THF)3: Mechanistic Insight and Synthetic Utility.

    PubMed

    Janjetovic, Mario; Ekebergh, Andreas; Träff, Annika M; Hilmersson, Göran

    2016-06-17

    A facile iodination protocol of unactivated alkyl fluorides using catalytic amounts of YbI3(THF)3 in the presence of iodotrimethylsilane as a stoichiometric fluoride trapping agent is presented. (1)H NMR spectroscopy demonstrates a two-step catalytic cycle where TMSI regenerates active YbI3(THF)3. Finally, the catalytic reaction is extended into a one-pot procedure to demonstrate a potential application of the method. Overall, the findings present a distinct strategy for C-F bond transformations in the presence of catalytic YbI3(THF)3. PMID:27243465

  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. Roles of N-Terminal Fatty Acid Acylations in Membrane Compartment Partitioning: Arabidopsis h-Type Thioredoxins as a Case Study[C][W

    PubMed Central

    Traverso, José A.; Micalella, Chiara; Martinez, Aude; Brown, Spencer C.; Satiat-Jeunemaître, Béatrice; Meinnel, Thierry; Giglione, Carmela

    2013-01-01

    N-terminal fatty acylations (N-myristoylation [MYR] and S-palmitoylation [PAL]) are crucial modifications affecting 2 to 4% of eukaryotic proteins. The role of these modifications is to target proteins to membranes. Predictive tools have revealed unexpected targets of these acylations in Arabidopsis thaliana and other plants. However, little is known about how N-terminal lipidation governs membrane compartmentalization of proteins in plants. We show here that h-type thioredoxins (h-TRXs) cluster in four evolutionary subgroups displaying strictly conserved N-terminal modifications. It was predicted that one subgroup undergoes only MYR and another undergoes both MYR and PAL. We used plant TRXs as a model protein family to explore the effect of MYR alone or MYR and PAL in the same family of proteins. We used a high-throughput biochemical strategy to assess MYR of specific TRXs. Moreover, various TRX–green fluorescent protein fusions revealed that MYR localized protein to the endomembrane system and that partitioning between this membrane compartment and the cytosol correlated with the catalytic efficiency of the N-myristoyltransferase acting at the N terminus of the TRXs. Generalization of these results was obtained using several randomly selected Arabidopsis proteins displaying a MYR site only. Finally, we demonstrated that a palmitoylatable Cys residue flanking the MYR site is crucial to localize proteins to micropatching zones of the plasma membrane. PMID:23543785

  10. Role of Acidic Residues in Helices TH8–TH9 in Membrane Interactions of the Diphtheria Toxin T Domain

    PubMed Central

    Ghatak, Chiranjib; Rodnin, Mykola V.; Vargas-Uribe, Mauricio; McCluskey, Andrew J.; Flores-Canales, Jose C.; Kurnikova, Maria; Ladokhin, Alexey S.

    2015-01-01

    The pH-triggered membrane insertion of the diphtheria toxin translocation domain (T domain) results in transferring the catalytic domain into the cytosol, which is relevant to potential biomedical applications as a cargo-delivery system. Protonation of residues is suggested to play a key role in the process, and residues E349, D352 and E362 are of particular interest because of their location within the membrane insertion unit TH8–TH9. We have used various spectroscopic, computational and functional assays to characterize the properties of the T domain carrying the double mutation E349Q/D352N or the single mutation E362Q. Vesicle leakage measurements indicate that both mutants interact with the membrane under less acidic conditions than the wild-type. Thermal unfolding and fluorescence measurements, complemented with molecular dynamics simulations, suggest that the mutant E362Q is more susceptible to acid destabilization because of disruption of native intramolecular contacts. Fluorescence experiments show that removal of the charge in E362Q, and not in E349Q/D352N, is important for insertion of TH8–TH9. Both mutants adopt a final functional state upon further acidification. We conclude that these acidic residues are involved in the pH-dependent action of the T domain, and their replacements can be used for fine tuning the pH range of membrane interactions. PMID:25875295

  11. Functionalization of a membrane sublayer using reverse filtration of enzymes and dopamine coating.

    PubMed

    Luo, Jianquan; Meyer, Anne S; Mateiu, R V; Kalyani, Dayanand; Pinelo, Manuel

    2014-12-24

    High permeability, high enzyme loading, and strong antifouling ability are the desired features for a biocatalytic membrane to be used in an enzymatic membrane reactor (EMR). To achieve these goals, the membrane sublayer was enriched with laccase by reverse filtration in this case, and the resulting enzyme-loaded sublayer was covered with a dopamine coating. After membrane reversal, the virgin membrane skin layer was facing the feed and the enzymes were entrapped by a polydopamine network in the membrane sublayer. Thus, the membrane sublayer was functionalized as a catalytically active layer. The effects of the original membrane properties (i.e., materials, pore size, and structure), enzyme type (i.e., laccase and alcohol dehydrogenase), and coating conditions (i.e., time and pH) on the resulting biocatalytic membrane permeability, enzyme loading, and activity were investigated. Using a RC10 kDa membrane with sponge-like sublayer to immobilize laccase with dopamine coating, the trade-off between permeability and enzyme loading was broken, and enzyme loading reached 44.5% without any permeability loss. After 85 days of storage and reuse 14 times, more than 80% of the immobilized laccase activity was retained for the membrane with a dopamine coating, while the relative activity was less than 40% without the coating. The resistance to high temperature and acidic/alkaline pH was also improved by the dopamine coating for the immobilized laccase. Moreover, this biocatalytic membrane could resist mild hydrodynamic cleaning (e.g., back-flushing), but the catalytic ability was reduced by chemical cleaning at extreme pH (e.g., 1.5 and 11.5). Since the immobilized enzyme is not directly facing the bulk of EMRs and the substrate can be specifically selected by the separation skin layer, this biocatalytic membrane is promising for cascade catalytic reactions. PMID:25420028

  12. Radiation-Grafted Polymer Electrolyte Membranes for Water Electrolysis Cells: Evaluation of Key Membrane Properties.

    PubMed

    Albert, Albert; Barnett, Alejandro O; Thomassen, Magnus S; Schmidt, Thomas J; Gubler, Lorenz

    2015-10-14

    Radiation-grafted membranes can be considered an alternative to perfluorosulfonic acid (PFSA) membranes, such as Nafion, in a solid polymer electrolyte electrolyzer. Styrene, acrylonitrile, and 1,3-diisopropenylbenzene monomers are cografted into preirradiated 50 μm ethylene tetrafluoroethylene (ETFE) base film, followed by sulfonation to introduce proton exchange sites to the obtained grafted films. The incorporation of grafts throughout the thickness is demonstrated by scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analysis of the membrane cross-sections. The membranes are analyzed in terms of grafting kinetics, ion-exchange capacity (IEC), and water uptake. The key properties of radiation-grafted membranes and Nafion, such as gas crossover, area resistance, and mechanical properties, are evaluated and compared. The plot of hydrogen crossover versus area resistance of the membranes results in a property map that indicates the target areas for membrane development for electrolyzer applications. Tensile tests are performed to assess the mechanical properties of the membranes. Finally, these three properties are combined to establish a figure of merit, which indicates that radiation-grafted membranes obtained in the present study are promising candidates with properties superior to those of Nafion membranes. A water electrolysis cell test is performed as proof of principle, including a comparison to a commercial membrane electrode assembly (MEA). PMID:26393461

  13. Do Membranes Dream of Electric Tubes? Advanced Membranes Using Carbon Nanotube - Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    de Lannoy, Charles-Francois Pedro Claude Karolek Ghislain

    Membrane technologies represent an energy efficient, effective solution for treating municipal and commercial waters/wastewaters. Membranes are predominantly polymer-based and despite steady advances in polymeric materials, they continue to suffer from operational problems including biofouling and breakages. This work addresses these two disparate problems by developing novel CNT-polymer nanocomposite materials that contain variously functionalized carbon nanotubes (fCNTs) in low quantities (<0.5wt%). Several strategies have been employed to achieve highly functional CNT-polymer nanocomposite membranes including blend mixing, ionic charge association, and covalent cross-linking with monomer and oligomer constituents. These CNT-polymer nanocomposite membranes were compared to traditional polymer membranes across various properties including increased Young's Modulus, changes in surface hydrophilicity, fine control over molecular weight cut-off and flux, and surface electrical conductivity. Membranes with high surface electrical conductivity were further tested for their anti-biofouling properties. Finally, CNT stability and polymer compatibility were evaluated throughout membrane manufacture, use, and cleaning. The incorporation of CNTs mixed in bulk phase and linked through ionic associations in polymer matrices showed significant (50%) increases in Young's modulus for certain CNT functionalizations and derivatization percent. Membranes formed with high surface electrical conductivity demonstrated almost complete resistance to biofouling (> 95%) in long-term bacterially challenged experiments. CNTs and polymer mixtures that lacked covalent or ionic bonds were susceptible to significant (up to 10%) loss of CNTs during membrane non-solvent gelation and aggressive chemical cleaning treatment. Functionalized carbon nanotubes endow polymer membranes with their unique strength and electrically conductive properties. These added properties were demonstrated to greatly

  14. Topological entropy of catalytic sets: Hypercycles revisited

    NASA Astrophysics Data System (ADS)

    Sardanyés, Josep; Duarte, Jorge; Januário, Cristina; Martins, Nuno

    2012-02-01

    The dynamics of catalytic networks have been widely studied over the last decades because of their implications in several fields like prebiotic evolution, virology, neural networks, immunology or ecology. One of the most studied mathematical bodies for catalytic networks was initially formulated in the context of prebiotic evolution, by means of the hypercycle theory. The hypercycle is a set of self-replicating species able to catalyze other replicator species within a cyclic architecture. Hypercyclic organization might arise from a quasispecies as a way to increase the informational containt surpassing the so-called error threshold. The catalytic coupling between replicators makes all the species to behave like a single and coherent evolutionary multimolecular unit. The inherent nonlinearities of catalytic interactions are responsible for the emergence of several types of dynamics, among them, chaos. In this article we begin with a brief review of the hypercycle theory focusing on its evolutionary implications as well as on different dynamics associated to different types of small catalytic networks. Then we study the properties of chaotic hypercycles with error-prone replication with symbolic dynamics theory, characterizing, by means of the theory of topological Markov chains, the topological entropy and the periods of the orbits of unimodal-like iterated maps obtained from the strange attractor. We will focus our study on some key parameters responsible for the structure of the catalytic network: mutation rates, autocatalytic and cross-catalytic interactions.

  15. Structure-based identification of catalytic residues

    PubMed Central

    Yahalom, Ran; Reshef, Dan; Wiener, Ayana; Frankel, Sagiv; Kalisman, Nir; Lerner, Boaz; Keasar, Chen

    2011-01-01

    The identification of catalytic residues is an essential step in functional characterization of enzymes. We present a purely structural approach to this problem, which is motivated by the difficulty of evolution-based methods to annotate structural genomics targets that have few or no homologs in the databases. Our approach combines a state-of-the-art support vector machine (SVM) classifier with novel structural features that augment structural clues by spatial averaging and Z-scoring. Special attention is paid to the class imbalance problem that stems from the overwhelming number of non-catalytic residues in enzymes compared to catalytic residues. This problem is tackled by: 1) optimizing the classifier to maximize a performance criterion that considers both type I and type II errors in the classification of catalytic and non-catalytic residues; 2) under-sampling non-catalytic residues before SVM training; and 3) during SVM training, penalizing errors in learning catalytic residues more than errors in learning non-catalytic residues. Tested on four enzyme datasets – one specifically designed by us to mimic the structural genomics scenario and three previously-evaluated datasets – our structure-based classifier is never inferior to similar structure-based classifiers and comparable to classifiers that use both structural and evolutionary features. In addition to evaluation of the performance of catalytic residue identification, we also present detailed case studies on three proteins. This analysis suggests that many false positive predictions may correspond to binding sites and other functional residues. A web server that implements the method, our own-designed database, and the source code of the programs are publicly available at http://www.cs.bgu.ac.il/~meshi/functionPrediction. PMID:21491495

  16. Structure-based identification of catalytic residues.

    PubMed

    Yahalom, Ran; Reshef, Dan; Wiener, Ayana; Frankel, Sagiv; Kalisman, Nir; Lerner, Boaz; Keasar, Chen

    2011-06-01

    The identification of catalytic residues is an essential step in functional characterization of enzymes. We present a purely structural approach to this problem, which is motivated by the difficulty of evolution-based methods to annotate structural genomics targets that have few or no homologs in the databases. Our approach combines a state-of-the-art support vector machine (SVM) classifier with novel structural features that augment structural clues by spatial averaging and Z scoring. Special attention is paid to the class imbalance problem that stems from the overwhelming number of non-catalytic residues in enzymes compared to catalytic residues. This problem is tackled by: (1) optimizing the classifier to maximize a performance criterion that considers both Type I and Type II errors in the classification of catalytic and non-catalytic residues; (2) under-sampling non-catalytic residues before SVM training; and (3) during SVM training, penalizing errors in learning catalytic residues more than errors in learning non-catalytic residues. Tested on four enzyme datasets, one specifically designed by us to mimic the structural genomics scenario and three previously evaluated datasets, our structure-based classifier is never inferior to similar structure-based classifiers and comparable to classifiers that use both structural and evolutionary features. In addition to the evaluation of the performance of catalytic residue identification, we also present detailed case studies on three proteins. This analysis suggests that many false positive predictions may correspond to binding sites and other functional residues. A web server that implements the method, our own-designed database, and the source code of the programs are publicly available at http://www.cs.bgu.ac.il/∼meshi/functionPrediction. PMID:21491495

  17. Effects of protein crowding on membrane systems.

    PubMed

    Guigas, Gernot; Weiss, Matthias

    2016-10-01

    Cellular membranes are typically decorated with a plethora of embedded and adsorbed macromolecules, e.g. proteins, that participate in numerous vital processes. With typical surface densities of 30,000 proteins per μm(2) cellular membranes are indeed crowded places that leave only few nanometers of private space for individual proteins. Here, we review recent advances in our understanding of protein crowding in membrane systems. We first give a brief overview on state-of-the-art approaches in experiment and simulation that are frequently used to study crowded membranes. After that, we review how crowding can affect diffusive transport of proteins and lipids in membrane systems. Next, we discuss lipid and protein sorting in crowded membrane systems, including effects like protein cluster formation, phase segregation, and lipid droplet formation. Subsequently, we highlight recent progress in uncovering crowding-induced conformational changes of membranes, e.g. membrane budding and vesicle formation. Finally, we give a short outlook on potential future developments in the field of crowded membrane systems. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26724385

  18. IRBIT Interacts with the Catalytic Core of Phosphatidylinositol Phosphate Kinase Type Iα and IIα through Conserved Catalytic Aspartate Residues

    PubMed Central

    Ando, Hideaki; Hirose, Matsumi; Gainche, Laura; Kawaai, Katsuhiro; Bonneau, Benjamin; Ijuin, Takeshi; Itoh, Toshiki; Takenawa, Tadaomi; Mikoshiba, Katsuhiko

    2015-01-01

    Phosphatidylinositol phosphate kinases (PIPKs) are lipid kinases that generate phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a critical lipid signaling molecule that regulates diverse cellular functions, including the activities of membrane channels and transporters. IRBIT (IP3R-binding protein released with inositol 1,4,5-trisphosphate) is a multifunctional protein that regulates diverse target proteins. Here, we report that IRBIT forms signaling complexes with members of the PIPK family. IRBIT bound to all PIPK isoforms in heterologous expression systems and specifically interacted with PIPK type Iα (PIPKIα) and type IIα (PIPKIIα) in mouse cerebellum. Site-directed mutagenesis revealed that two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are involved in the interaction with IRBIT. Furthermore, phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfered with the interaction, suggesting that IRBIT interacts with catalytic cores of PIPKs. Mutations of phosphorylation sites in the serine-rich region of IRBIT affected the selectivity of its interaction with PIPKIα and PIPKIIα. The structural flexibility of the serine-rich region, located in the intrinsically disordered protein region, is assumed to underlie the mechanism of this interaction. Furthermore, in vitro binding experiments and immunocytochemistry suggest that IRBIT and PIPKIα interact with the Na+/HCO3− cotransporter NBCe1-B. These results suggest that IRBIT forms signaling complexes with PIPKIα and NBCe1-B, whose activity is regulated by PI(4,5)P2. PMID:26509711

  19. Effect of Porosity on Surface Catalytic Efficiency

    NASA Technical Reports Server (NTRS)

    Stewart, David A.; Pallix, Joan; Rasky, Daniel J. (Technical Monitor)

    1994-01-01

    This paper describes the effect of surface porosity of thermal protection materials on surface catalytic efficiency using test data taken from both arc-jet and side-arm reactor facilities. Relative surface porosity of the samples varied from 6% to 50%. Surface porosity was measured using a flow apparatus and Bernoulli equation. The surface catalytic efficiency of the materials was calculated using aerothermodynamic, and kinetic theories. The catalytic efficiency of the materials are compared at surface temperatures between room temperature and 2500 F. The data are presented in the form of graphs and tables.

  20. 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.

  1. A charged membrane paradigm at large D

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Sayantani; Mandlik, Mangesh; Minwalla, Shiraz; Thakur, Somyadip

    2016-04-01

    We study the effective dynamics of black hole horizons in Einstein-Maxwell theory in a large number of spacetime dimensions D. We demonstrate that horizon dynamics may be recast as a well posed initial value problem for the motion of a codimension one non gravitational membrane moving in flat space. The dynamical degrees of freedom of this membrane are its shape, charge density and a divergence free velocity field. We determine the equations that govern membrane dynamics at leading order in the large D expansion. Our derivation of the membrane equations assumes that the solution preserves an SO( D - p - 2) isometry with p held fixed as D is taken to infinity. However we are able to cast our final membrane equations into a completely geometric form that makes no reference to this symmetry algebra.

  2. Final Report

    SciTech Connect

    Taylor, Philip L.

    2012-11-11

    Our research program was aimed at elucidating the nature of proton transport in ionomer membranes by means of a combination of analytical theory and molecular modeling. There were two broad thrusts. The first of these was directed towards understanding the equilibrium structure of Nafion and related polymers at various levels of hydration. The second thrust was concerned with the transport of protons through a membrane of this type. The research on structure proceeded by building on existing work, but with the introduction of some novel techniques, among which is a hybrid Molecular Dynamics--Monte Carlo approach. This method permits rapid computations by temporarily decoupling the motion of the polar side chains from that of the perfluorinated backbone, while still retaining the essential aspects of the constraint that phase separation can only continue to a very limited degree. Competition between an elastic energy due to this constraint and the tendency to phase separation lead to the equilibrium structure, which turns out to be qualitatively different at different levels of hydration. The use of a carefully formulated dielectric function was necessary to achieve accurate results. The work on transport of protons in Nafion-like membranes also involved a combination of theory and simulation. Atomistic molecular-dynamics simulations were employed to determine some of the characteristic parameters for the diffusion of hydronium in hydrated membranes. These results were used in a theoretical model of non-linear diffusion to predict transport coefficients. Among our results was the discovery that treatment with strong electric fields may enhance the properties of the polymer membranes. Our computer simulations showed that the vigorous application of a stretching force or an electric field can modify the structure of the ionomer that lies at the heart of a polymer-electrolyte-membrane fuel cell. If these predictions are verified experimentally, then it should be

  3. Composite sensor membrane

    DOEpatents

    Majumdar, Arun; Satyanarayana, Srinath; Yue, Min

    2008-03-18

    A sensor may include a membrane to deflect in response to a change in surface stress, where a layer on the membrane is to couple one or more probe molecules with the membrane. The membrane may deflect when a target molecule reacts with one or more probe molecules.

  4. Self-propulsion and interactions of catalytic particles in a chemically active medium

    NASA Astrophysics Data System (ADS)

    Banigan, Edward J.; Marko, John F.

    2016-01-01

    Enzymatic "machines," such as catalytic rods or colloids, can self-propel and interact by generating gradients of their substrates. We theoretically investigate the behaviors of such machines in a chemically active environment where their catalytic substrates are continuously synthesized and destroyed, as occurs in living cells. We show how the kinetic properties of the medium modulate self-propulsion and pairwise interactions between machines, with the latter controlled by a tunable characteristic interaction range analogous to the Debye screening length in an electrolytic solution. Finally, we discuss the effective force arising between interacting machines and possible biological applications, such as partitioning of bacterial plasmids.

  5. 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.

  6. 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

  7. 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

  8. Liquid Droplets on a Highly Deformable Membrane

    NASA Astrophysics Data System (ADS)

    Schulman, Rafael D.; Dalnoki-Veress, Kari

    2015-11-01

    We examine the deformation produced by microdroplets atop thin elastomeric and glassy free-standing films. Because of the Laplace pressure, the droplets deform the elastic membrane thereby forming a bulge. Thus, two angles define the droplet or membrane geometry: the angles the deformed bulge and the liquid surface make with the film. These angles are measured as a function of the film tension, and are in excellent agreement with a force balance at the contact line. Finally, we find that if the membrane has an anisotropic tension, the droplets are no longer spherical but become elongated along the direction of high tension.

  9. A review of tin oxide-based catalytic systems: Preparation, characterization and catalytic behavior

    NASA Technical Reports Server (NTRS)

    Hoflund, Gar B.

    1987-01-01

    This paper reviews the important aspects of the preparation, characterization and catalytic behavior of tin oxide-based catalytic systems including doped tin oxide, mixed oxides which contain tin oxide, Pt supported on tin oxide and Pt/Sn supported on alumina. These systems have a broad range of applications and are continually increasing in importance. However, due to their complex nature, much remains to be understood concerning how they function catalytically.

  10. Catalytic microwave pyrolysis of biomass for renewable phenols and fuels

    NASA Astrophysics Data System (ADS)

    Bu, Quan

    Bio-oil is an unstable intermediate and needs to be upgraded before its use. This study focused on improving the selectivity of bio-oilby catalytic pyrolysis of biomass using activated carbon (AC) catalysts. Firstly, the effects of process conditions on product quality and product yield were investigated by catalytic microwave pyrolysis of biomass using AC as a catalyst. The optimized reaction condition for bio-oil and volatile was determined. Chemical composition analysis by GC/MS showed that phenols rich bio-oils were obtained. Furthermore, the effects of different carbon sources based AC catalysts on products yield and chemical composition selectivity of obtained bio-oils were investigated during microwave pyrolysis of Douglas fir pellet. The catalysts recycling test of the selected catalysts indicated that the AC catalysts can be used for 3-4 times with high concentration of phenolic compounds. The individual surface polar/acidic oxygen functional groups analysis suggested the changes of functional groups in ACs explained the reaction mechanism of this process. In addition, the potential for production of renewable phenols and fuels by catalytic pyrolysis of biomass using lignin as a model compound was explored. The main chemical compounds of the obtained bio-oils were phenols, guaiacols, hydrocarbons and esters. The thermal decomposition behaviors of lignin and kinetics study were investigated by TGA. The change of functional groups of AC catalyst indicated the bio-oil reduction was related to the reaction mechanism of this process. Finally, the effects of Fe-modified AC catalyst on bio-oil upgrading and kintic study of biomass pyrolysis were investigated. The catalytic pyrolysis of biomass using the Fe-modified AC catalyst may promote the occurrence of the fragmentation of cellulose, rather than repolymerization as in the non-catalytic pyrolysis which leads to partial of guaiacols derived from furans. Results showed that the main chemical compounds of bio

  11. CATALYTIC OXIDATION OF GROUNDWATER STRIPPING EMISSIONS

    EPA Science Inventory

    The paper reviews the applicability of catalytic oxidation to control ground-water air stripping gaseous effluents, with special attention to system designs and case histories. The variety of contaminants and catalyst poisons encountered in stripping operations are also reviewed....

  12. Catalytic Aminohalogenation of Alkenes and Alkynes

    PubMed Central

    Chemler, Sherry R.; Bovino, Michael T.

    2013-01-01

    Catalytic aminohalogenation methods enable the regio- and stereoselective vicinal difunctionalization of alkynes, allenes and alkenes with amine and halogen moieties. A range of protocols and reaction mechanisms including organometallic, Lewis base, Lewis acid and Brønsted acid catalysis have been disclosed, enabling the regio- and stereoselective synthesis of halogen-functionalized acyclic amines and nitrogen heterocycles. Recent advances including aminofluorination and catalytic enantioselective aminohalogenation reactions are summarized in this review. PMID:23828735

  13. An Iron Reservoir to the Catalytic Metal

    PubMed Central

    Liu, Fange; Geng, Jiafeng; Gumpper, Ryan H.; Barman, Arghya; Davis, Ian; Ozarowski, Andrew; Hamelberg, Donald; Liu, Aimin

    2015-01-01

    The rubredoxin motif is present in over 74,000 protein sequences and 2,000 structures, but few have known functions. A secondary, non-catalytic, rubredoxin-like iron site is conserved in 3-hydroxyanthranilate 3,4-dioxygenase (HAO), from single cellular sources but not multicellular sources. Through the population of the two metal binding sites with various metals in bacterial HAO, the structural and functional relationship of the rubredoxin-like site was investigated using kinetic, spectroscopic, crystallographic, and computational approaches. It is shown that the first metal presented preferentially binds to the catalytic site rather than the rubredoxin-like site, which selectively binds iron when the catalytic site is occupied. Furthermore, an iron ion bound to the rubredoxin-like site is readily delivered to an empty catalytic site of metal-free HAO via an intermolecular transfer mechanism. Through the use of metal analysis and catalytic activity measurements, we show that a downstream metabolic intermediate can selectively remove the catalytic iron. As the prokaryotic HAO is often crucial for cell survival, there is a need for ensuring its activity. These results suggest that the rubredoxin-like site is a possible auxiliary iron source to the catalytic center when it is lost during catalysis in a pathway with metabolic intermediates of metal-chelating properties. A spare tire concept is proposed based on this biochemical study, and this concept opens up a potentially new functional paradigm for iron-sulfur centers in iron-dependent enzymes as transient iron binding and shuttling sites to ensure full metal loading of the catalytic site. PMID:25918158

  14. Chemical and catalytic properties of elemental carbon

    SciTech Connect

    Chang, S.G.; Brodzinsky, R.; Gundel, L.A.; Novakov, T.

    1980-10-01

    Elemental carbon particles resulting from incomplete combustion of fossil fuel are one of the major constituents of airborne particulate matter. These particles are a chemically and catalytically active material and can be an effective carrier for other toxic air pollutants through their adsorptive capability. The chemical, adsorptive, and catalytic behaviors of carbon particles depend very much on their crystalline structure, surface composition, and electronic properties. This paper discusses these properties and examines their relevance to atmospheric chemistry.

  15. Catalytic Radical Domino Reactions in Organic Synthesis

    PubMed Central

    Sebren, Leanne J.; Devery, James J.; Stephenson, Corey R.J.

    2014-01-01

    Catalytic radical-based domino reactions represent important advances in synthetic organic chemistry. Their development benefits synthesis by providing atom- and step-economical methods to complex molecules. Intricate combinations of radical, cationic, anionic, oxidative/reductive, and transition metal mechanistic steps result in cyclizations, additions, fragmentations, ring-expansions, and rearrangements. This Perspective summarizes recent developments in the field of catalytic domino processes. PMID:24587964

  16. Correlation of Catalytic Rates With Solubility Parameters

    NASA Technical Reports Server (NTRS)

    Lawson, Daniel D.; England, Christopher

    1987-01-01

    Catalyst maximizes activity when its solubility parameter equals that of reactive species. Catalytic activities of some binary metal alloys at maximum when alloy compositions correspond to Hildebrand solubility parameters equal to those of reactive atomic species on catalyst. If this suggestive correlation proves to be general, applied to formulation of other mixed-metal catalysts. Also used to identify reactive species in certain catalytic reactions.

  17. Transformation of iron oxides on PI electrospun membranes

    NASA Astrophysics Data System (ADS)

    Li, Penggang; Lv, Fengzhu; Liu, Leipeng; Ding, Ling; Zhang, Yihe

    2016-09-01

    Iron oxides/PI fiber membranes, especially magnetic PI membranes, are important flexible porous materials available application in the field of wave absorption, magnetic recording, membrane separation and catalysts. Therefore, α-Fe2O3 loaded PI composite fibers were prepared by electrospinning of poly(amic acid) PAA solution followed by loading Fe3+ on the PAA membrane by ion-exchange and then imidization. Then the α-Fe2O3 on PI membrane were reduced by H2 to give magnetic PI membranes. The content of α-Fe2O3 and Fe3O4 on PI can be controlled by adjustment the ion-exchange time. The saturation magnetization of the composite membranes can reach up to 4 emu/g and the final composite membranes have magnetic response ability.

  18. Materials for next-generation desalination and water purification membranes

    NASA Astrophysics Data System (ADS)

    Werber, Jay R.; Osuji, Chinedum O.; Elimelech, Menachem

    2016-05-01

    Membrane-based separations for water purification and desalination have been increasingly applied to address the global challenges of water scarcity and the pollution of aquatic environments. However, progress in water purification membranes has been constrained by the inherent limitations of conventional membrane materials. Recent advances in methods for controlling the structure and chemical functionality in polymer films can potentially lead to new classes of membranes for water purification. In this Review, we first discuss the state of the art of existing membrane technologies for water purification and desalination, highlight their inherent limitations and establish the urgent requirements for next-generation membranes. We then describe molecular-level design approaches towards fabricating highly selective membranes, focusing on novel materials such as aquaporin, synthetic nanochannels, graphene and self-assembled block copolymers and small molecules. Finally, we highlight promising membrane surface modification approaches that minimize interfacial interactions and enhance fouling resistance.

  19. Catalytic partial oxidation of pyrolysis oils

    NASA Astrophysics Data System (ADS)

    Rennard, David Carl

    2009-12-01

    This thesis explores the catalytic partial oxidation (CPO) of pyrolysis oils to syngas and chemicals. First, an exploration of model compounds and their chemistries under CPO conditions is considered. Then CPO experiments of raw pyrolysis oils are detailed. Finally, plans for future development in this field are discussed. In Chapter 2, organic acids such as propionic acid and lactic acid are oxidized to syngas over Pt catalysts. Equilibrium production of syngas can be achieved over Rh-Ce catalysts; alternatively mechanistic evidence is derived using Pt catalysts in a fuel rich mixture. These experiments show that organic acids, present in pyrolysis oils up to 25%, can undergo CPO to syngas or for the production of chemicals. As the fossil fuels industry also provides organic chemicals such as monomers for plastics, the possibility of deriving such species from pyrolysis oils allows for a greater application of the CPO of biomass. However, chemical production is highly dependent on the originating molecular species. As bio oil comprises up to 400 chemicals, it is essential to understand how difficult it would be to develop a pure product stream. Chapter 3 continues the experimentation from Chapter 2, exploring the CPO of another organic functionality: the ester group. These experiments demonstrate that equilibrium syngas production is possible for esters as well as acids in autothermal operation with contact times as low as tau = 10 ms over Rh-based catalysts. Conversion for these experiments and those with organic acids is >98%, demonstrating the high reactivity of oxygenated compounds on noble metal catalysts. Under CPO conditions, esters decompose in a predictable manner: over Pt and with high fuel to oxygen, non-equilibrium products show a similarity to those from related acids. A mechanism is proposed in which ethyl esters thermally decompose to ethylene and an acid, which decarbonylates homogeneously, driven by heat produced at the catalyst surface. Chapter 4

  20. A Structure-Based Approach for Detection of Thiol Oxidoreductases and Their Catalytic Redox-Active Cysteine Residues

    PubMed Central

    Marino, Stefano M.; Gladyshev, Vadim N.

    2009-01-01

    Cysteine (Cys) residues often play critical roles in proteins, for example, in the formation of structural disulfide bonds, metal binding, targeting proteins to the membranes, and various catalytic functions. However, the structural determinants for various Cys functions are not clear. Thiol oxidoreductases, which are enzymes containing catalytic redox-active Cys residues, have been extensively studied, but even for these proteins there is little understanding of what distinguishes their catalytic redox Cys from other Cys functions. Herein, we characterized thiol oxidoreductases at a structural level and developed an algorithm that can recognize these enzymes by (i) analyzing amino acid and secondary structure composition of the active site and its similarity to known active sites containing redox Cys and (ii) calculating accessibility, active site location, and reactivity of Cys. For proteins with known or modeled structures, this method can identify proteins with catalytic Cys residues and distinguish thiol oxidoreductases from the enzymes containing other catalytic Cys types. Furthermore, by applying this procedure to Saccharomyces cerevisiae proteins containing conserved Cys, we could identify the majority of known yeast thiol oxidoreductases. This study provides insights into the structural properties of catalytic redox-active Cys and should further help to recognize thiol oxidoreductases in protein sequence and structure databases. PMID:19424433

  1. Human airway epithelia express catalytically active NEU3 sialidase

    PubMed Central

    Hyun, Sang Won; Feng, Chiguang; Zhang, Lei; Liu, Anguo; Guang, Wei; Nguyen, Chinh; Sun, Wenji; Luzina, Irina G.; Webb, Tonya J.; Atamas, Sergei P.; Passaniti, Antonino; Twaddell, William S.; Puché, Adam C.; Wang, Lai-Xi; Cross, Alan S.; Goldblum, Simeon E.

    2014-01-01

    Sialic acids on glycoconjugates play a pivotal role in many biological processes. In the airways, sialylated glycoproteins and glycolipids are strategically positioned on the plasma membranes of epithelia to regulate receptor-ligand, cell-cell, and host-pathogen interactions at the molecular level. We now demonstrate, for the first time, sialidase activity for ganglioside substrates in human airway epithelia. Of the four known mammalian sialidases, NEU3 has a substrate preference for gangliosides and is expressed at mRNA and protein levels at comparable abundance in epithelia derived from human trachea, bronchi, small airways, and alveoli. In small airway and alveolar epithelia, NEU3 protein was immunolocalized to the plasma membrane, cytosolic, and nuclear subcellular fractions. Small interfering RNA-induced silencing of NEU3 expression diminished sialidase activity for a ganglioside substrate by >70%. NEU3 immunostaining of intact human lung tissue could be localized to the superficial epithelia, including the ciliated brush border, as well as to nuclei. However, NEU3 was reduced in subepithelial tissues. These results indicate that human airway epithelia express catalytically active NEU3 sialidase. PMID:24658138

  2. Method of fabricating electrode catalyst layers with directionally oriented carbon support for proton exchange membrane fuel cell

    DOEpatents

    Liu, Di-Jia; Yang, Junbing

    2012-03-20

    A membrane electrode assembly (MEA) of the invention comprises an anode and a cathode and a proton conductive membrane therebetween, the anode and the cathode each comprising a patterned sheet of longitudinally aligned transition metal-containing carbon nanotubes, wherein the carbon nanotubes are in contact with and are aligned generally perpendicular to the membrane, wherein a catalytically active transition metal is incorporated throughout the nanotubes.

  3. Catalytic hydrogenation of carbon monoxide

    SciTech Connect

    Wayland, B.B.

    1992-12-01

    This project is focused on developing strategies to accomplish the reduction and hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. Our approaches to this issue are based on the recognition that rhodium macrocycles have unusually favorable thermodynamic values for producing a series of intermediate implicated in the catalytic hydrogenation of CO. Observations of metalloformyl complexes produced by reactions of H{sub 2} and CO, and reductive coupling of CO to form metallo {alpha}-diketone species have suggested a multiplicity of routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in constructing energy profiles for a variety of potential pathways, and these schemes are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. Variation of the electronic and steric effects associated with the ligand arrays along with the influences of the reaction medium provide the chemical tools for tuning these factors. Emerging knowledge of the factors that contribute to M-H, M-C and M-O bond enthalpies is directing the search for ligand arrays that will expand the range of metal species that have favorable thermodynamic parameters to produce the primary intermediates for CO hydrogenation. Studies of rhodium complexes are being extended to non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics. Multifunctional catalyst systems designed to couple the ability of rhodium complexes to produce formyl and diketone intermediates with a second catalyst that hydrogenates these imtermediates are promising approaches to accomplish CO hydrogenation at mild conditions.

  4. Sheet Membrane Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  5. Formylglycine, a Post-Translationally Generated Residue with Unique Catalytic Capabilities and Biotechnology Applications

    PubMed Central

    Appel, Mason J.; Bertozzi, Carolyn R.

    2015-01-01

    Formylglycine (fGly) is a catalytically essential residue found almost exclusively in the active sites of type I sulfatases. Formed by post-translational oxidation of cysteine or serine side chains, this aldehyde-functionalized residue participates in a unique and highly efficient catalytic mechanism for sulfate ester hydrolysis. The enzymes that produce fGly, formylglycine-generating enzyme (FGE) and anaerobic sulfatase-maturating enzyme (anSME), are as unique and specialized as fGly itself. FGE especially is structurally and mechanistically distinct, and serves the sole function of activating type I sulfatase targets. This review summarizes the current state of knowledge regarding the mechanism by which fGly contributes to sulfate ester hydrolysis, the molecular details of fGly biogenesis by FGE and anSME, and finally, recent biotechnology applications of fGly beyond its natural catalytic function. PMID:25514000

  6. Formylglycine, a post-translationally generated residue with unique catalytic capabilities and biotechnology applications.

    PubMed

    Appel, Mason J; Bertozzi, Carolyn R

    2015-01-16

    Formylglycine (fGly) is a catalytically essential residue found almost exclusively in the active sites of type I sulfatases. Formed by post-translational oxidation of cysteine or serine side chains, this aldehyde-functionalized residue participates in a unique and highly efficient catalytic mechanism for sulfate ester hydrolysis. The enzymes that produce fGly, formylglycine-generating enzyme (FGE) and anaerobic sulfatase-maturating enzyme (anSME), are as unique and specialized as fGly itself. FGE especially is structurally and mechanistically distinct, and serves the sole function of activating type I sulfatase targets. This review summarizes the current state of knowledge regarding the mechanism by which fGly contributes to sulfate ester hydrolysis, the molecular details of fGly biogenesis by FGE and anSME, and finally, recent biotechnology applications of fGly beyond its natural catalytic function. PMID:25514000

  7. An investigation on the catalytic capacity of dolomite in transesterification and the calculation of kinetic parameters.

    PubMed

    Niu, Sheng-Li; Huo, Meng-Jia; Lu, Chun-Mei; Liu, Meng-Qi; Li, Hui

    2014-04-01

    The catalytic capacity of dolomite in transesterification was investigated and the kinetic parameters were calculated. The activated dolomites as transesterification catalyst were characterized by X-ray diffraction, nitrogen adsorption and desorption and Hammett indicator method, where the original dolomite was analyzed by thermogravimetric and X-ray fluorescence in advance. Its potential catalytic capacity was validated from aspects of the activated temperature and the reused property, where the reliability of the experimental system was also examined. Then, influences of the catalyst added amount, the mole ratio of methanol to oil, the transesterification temperature and the transesterification time on the catalytic capacity were investigated. Finally, kinetic parameters of the transesterification catalyzed by the activated dolomite were calculated. PMID:24583217

  8. Biochemical heterogeneity of skeletal-muscle microsomal membranes. Membrane origin, membrane specificity and fibre types

    PubMed Central

    Salviati, Giovanni; Volpe, Pompeo; Salvatori, Sergio; Betto, Romeo; Damiani, Ernesto; Margreth, Alfredo; Pasquali-Ronchetti, Ivonne

    1982-01-01

    1. Microsomes were isolated from rabbit fast-twitch and slow-twitch muscle and were separated into heavy and light fractions by centrifugation in a linear (0.3–2m) sucrose density gradient. The membrane origin of microsomal vesicles was investigated by studying biochemical markers of the sarcoplasmic-reticulum membranes and of surface and T-tubular membranes, as well as their freeze-fracture properties. 2. Polyacrylamide-gel electrophoresis showed differences in the Ca2+-dependent ATPase/calsequestrin ratio between heavy and light fractions, which were apparently consistent with their respective origin from cisternal and longitudinal sarcoplasmic reticulum, as well as unrelated differences, such as peptides specific to slow-muscle microsomes (mol.wts. 76000, 60000, 56000 and 45000). 3. Freeze-fracture electron microscopy of muscle microsomes demonstrated that vesicles truly derived from the sarcoplasmic reticulum, with an average density of 9nm particles on the concave face of about 3000/μm2 for both fast and slow muscle, were admixed with vesicles with particle densities below 1000/μm2. 4. As determined in the light fractions, the sarcoplasmic-reticulum vesicles accounted for 84% and 57% of the total number of microsomal vesicles, for fast and slow muscle respectively. These values agreed closely with the percentage values of Ca2+-dependent ATPase protein obtained by gel densitometry. 5. The T-tubular origin of vesicles with a smooth concave fracture face in slow-muscle microsomes is supported by their relative high content in total phospholipid and cholesterol, compared with the microsomes of fast muscle, and by other correlative data, such as the presence of (Na++K+)-dependent ATPase activity and of low amounts of Na+-dependent membrane phosphorylation. 6. Among intrinsic sarcoplasmic-reticulum membrane proteins, a proteolipid of mol.wt. 12000 is shown to be identical in the microsomes of both fast and slow muscle and the Ca2+-dependent ATPase to be

  9. Methanotroph outer membrane preparation.

    PubMed

    Karlsen, Odd A; Berven, Frode S; Jensen, Harald B; Fjellbirkeland, Anne

    2011-01-01

    All presently known methanotrophs are gram-negative bacteria suggesting that they are surrounded by a two-layered membrane: an inner or cytoplasmic membrane and an outer membrane. In the methanotroph Methylococcus capsulatus (Bath), separation of the two membranes has allowed studies on protein and lipid composition of the outer membrane. Its outer membrane can be isolated from purified cell envelopes by selective solubilization of the inner membranes with the detergent Triton X-100. The proteins associated with the outer membrane can further be fractionated into integral and tightly associated proteins and peripheral loosely associated proteins. We present here protocols for this fractionation and show how the proteins associated with the outer leaflet of the outer membrane can be isolated and identified by whole-cell biotin surface labeling. PMID:21419921

  10. Development of membrane electrode assembly for high temperature proton exchange membrane fuel cell by catalyst coating membrane method

    NASA Astrophysics Data System (ADS)

    Liang, Huagen; Su, Huaneng; Pollet, Bruno G.; Pasupathi, Sivakumar

    2015-08-01

    Membrane electrode assembly (MEA), which contains cathode and anode catalytic layer, gas diffusion layers (GDL) and electrolyte membrane, is the key unit of a PEMFC. An attempt to develop MEA for ABPBI membrane based high temperature (HT) PEMFC is conducted in this work by catalyst coating membrane (CCM) method. The structure and performance of the MEA are examined by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and I-V curve. Effects of the CCM preparation method, Pt loading and binder type are investigated for the optimization of the single cell performance. Under 160 °C and atmospheric pressure, the peak power density of the MEA, with Pt loading of 0.5 mg cm-2 and 0.3 mg cm-2 for the cathode and the anode, can reach 277 mW cm-2, while a current density of 620 A cm-2 is delivered at the working voltage of 0.4 V. The MEA prepared by CCM method shows good stability operating in a short term durability test: the cell voltage maintained at ∼0.45 V without obvious drop when operated at a constant current density of 300 mA cm-2 and 160 °C under ambient pressure for 140 h.

  11. Mechanisms of membrane toxicity of hydrocarbons.

    PubMed Central

    Sikkema, J; de Bont, J A; Poolman, B

    1995-01-01

    Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated. PMID:7603409

  12. Regulation of a muralytic enzyme by dynamic membrane topology

    SciTech Connect

    Sun, Qingan; Kuty, Gabriel F.; Arockiasamy, Arulandu; Xu, Min; Young, Ry; Sacchettini, James C.

    2010-08-16

    R{sup 21}, the lysozyme of coliphage 21, has an N-terminal signal-anchor-release (SAR) domain that directs its secretion in a membrane-tethered, inactive form and then its release and activation in the periplasm. Both genetic and crystallographic studies show that the SAR domain, once extracted from the bilayer, refolds into the body of the enzyme and effects muralytic activation by repositioning one residue of the canonical lysozyme catalytic triad.

  13. Membrane selectivity in pervaporation

    SciTech Connect

    Kujawski, W.

    1996-06-01

    A qualitative description is presented of pervaporation which discusses the initial preferential sorption into the membrane, diffusion of liquid, phase transition from liquid to vapor phase, followed by diffusion of vapors and fast desorption from the other side of the membrane. The overall separation of each pervaporation step was calculated in terms of separation factor {alpha}. The results show that in the case of hydrophilic membranes (i.e., dense polyamide-6 membrane and ion-exchange membrane PESS-1) and water-ethanol mixtures, the phase transition step decreases the overall separation. Also, diffusion through the membrane is unfavorable to water at a low concentration range.

  14. The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers

    SciTech Connect

    Olek, Anna T.; Rayon, Catherine; Makowski, Lee; Kim, Hyung Rae; Ciesielski, Peter; Badger, John; Paul, Lake N.; Ghosh, Subhangi; Kihara, Daisuke; Crowley, Michael; Himmel, Michael E.; Bolin, Jeffrey T.; Carpita, Nicholas C.

    2014-07-10

    Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice (Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongated structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. As a result, the arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize.

  15. The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers

    DOE PAGESBeta

    Olek, Anna T.; Rayon, Catherine; Makowski, Lee; Kim, Hyung Rae; Ciesielski, Peter; Badger, John; Paul, Lake N.; Ghosh, Subhangi; Kihara, Daisuke; Crowley, Michael; et al

    2014-07-10

    Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice (Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongatedmore » structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. As a result, the arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize.« less

  16. The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers.

    PubMed

    Olek, Anna T; Rayon, Catherine; Makowski, Lee; Kim, Hyung Rae; Ciesielski, Peter; Badger, John; Paul, Lake N; Ghosh, Subhangi; Kihara, Daisuke; Crowley, Michael; Himmel, Michael E; Bolin, Jeffrey T; Carpita, Nicholas C

    2014-07-01

    Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice (Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongated structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. The arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize. PMID:25012190

  17. SOFC system with integrated catalytic fuel processing

    NASA Astrophysics Data System (ADS)

    Finnerty, Caine; Tompsett, Geoff. A.; Kendall, Kevin; Ormerod, R. Mark

    In recent years, there has been much interest in the development of solid oxide fuel cell technology operating directly on hydrocarbon fuels. The development of a catalytic fuel processing system, which is integrated with the solid oxide fuel cell (SOFC) power source is outlined here. The catalytic device utilises a novel three-way catalytic system consisting of an in situ pre-reformer catalyst, the fuel cell anode catalyst and a platinum-based combustion catalyst. The three individual catalytic stages have been tested in a model catalytic microreactor. Both temperature-programmed and isothermal reaction techniques have been applied. Results from these experiments were used to design the demonstration SOFC unit. The apparatus used for catalytic characterisation can also perform in situ electrochemical measurements as described in previous papers [C.M. Finnerty, R.H. Cunningham, K. Kendall, R.M. Ormerod, Chem. Commun. (1998) 915-916; C.M. Finnerty, N.J. Coe, R.H. Cunningham, R.M. Ormerod, Catal. Today 46 (1998) 137-145]. This enabled the performance of the SOFC to be determined at a range of temperatures and reaction conditions, with current output of 290 mA cm -2 at 0.5 V, being recorded. Methane and butane have been evaluated as fuels. Thus, optimisation of the in situ partial oxidation pre-reforming catalyst was essential, with catalysts producing high H 2/CO ratios at reaction temperatures between 873 K and 1173 K being chosen. These included Ru and Ni/Mo-based catalysts. Hydrocarbon fuels were directly injected into the catalytic SOFC system. Microreactor measurements revealed the reaction mechanisms as the fuel was transported through the three-catalyst device. The demonstration system showed that the fuel processing could be successfully integrated with the SOFC stack.

  18. VOC Destruction by Catalytic Combustion Microturbine

    SciTech Connect

    Tom Barton

    2009-03-10

    This project concerned the application of a catalytic combustion system that has been married to a micro-turbine device. The catalytic combustion system decomposes the VOC's and transmits these gases to the gas turbine. The turbine has been altered to operate on very low-level BTU fuels equivalent to 1.5% methane in air. The performance of the micro-turbine for VOC elimination has some flexibility with respect to operating conditions, and the system is adaptable to multiple industrial applications. The VOC source that was been chosen for examination was the emissions from coal upgrading operations. The overall goal of the project was to examine the effectiveness of a catalytic combustion based system for elimination of VOCs while simultaneously producing electrical power for local consumption. Project specific objectives included assessment of the feasibility for using a Flex-Microturbine that generates power from natural gas while it consumes VOCs generated from site operations; development of an engineering plan for installation of the Flex-Microturbine system; operation of the micro-turbine through various changes in site and operation conditions; measurement of the VOC destruction quantitatively; and determination of the required improvements for further studies. The micro-turbine with the catalytic bed worked effectively to produce power on levels of fuel much lower than the original turbine design. The ability of the device to add or subtract supplemental fuel to augment the amount of VOC's in the inlet air flow made the device an effective replacement for a traditional flare. Concerns about particulates in the inlet flow and the presence of high sulfur concentrations with the VOC mixtures was identified as a drawback with the current catalytic design. A new microturbine design was developed based on this research that incorporates a thermal oxidizer in place of the catalytic bed for applications where particulates or contamination would limit the lifetime of

  19. Reactivity and Catalytic Activity of Hydrogen Atom Chemisorbed Silver Clusters.

    PubMed

    Manzoor, Dar; Pal, Sourav

    2015-06-18

    Metal clusters of silver have attracted recent interest of researchers as a result of their potential in different catalytic applications and low cost. However, due to the completely filled d orbital and very high first ionization potential of the silver atom, the silver-based catalysts interact very weakly with the reacting molecules. In the current work, density functional theory calculations were carried out to investigate the effect of hydrogen atom chemisorption on the reactivity and catalytic properties of inert silver clusters. Our results affirm that the hydrogen atom chemisorption leads to enhancement in the binding energy of the adsorbed O2 molecule on the inert silver clusters. The increase in the binding energy is also characterized by the decrease in the Ag-O and increase in the O-O bond lengths in the case of the AgnH silver clusters. Pertinent to the increase in the O-O bond length, a significant red shift in the O-O stretching frequency is also noted in the case of the AgnH silver clusters. Moreover, the hydrogen atom chemisorbed silver clusters show low reaction barriers and high heat of formation of the final products for the environmentally important CO oxidation reaction as compared to the parent catalytically inactive clusters. The obtained results were compared with those of the corresponding gold and hydrogen atom chemisorbed gold clusters obtained at the same level of theory. It is expected the current computational study will provide key insights for future advances in the design of efficient nanosilver-based catalysts through the adsorption of a small atom or a ligand. PMID:25988294

  20. Ambidextrous Binding of Cell and Membrane Bilayers by Soluble Matrix Metalloproteinase-12

    PubMed Central

    Koppisetti, Rama K.; Fulcher, Yan G.; Jurkevich, Alexander; Prior, Stephen H.; Xu, Jia; Lenoir, Marc; Overduin, Michael; Van Doren, Steven R.

    2014-01-01

    Matrix metalloproteinases (MMPs) regulate tissue remodeling, inflammation, and disease progression. Some soluble MMPs are inexplicably active near cell surfaces. Here, we demonstrate binding of MMP-12 directly to bilayers and cellular membranes using paramagnetic NMR and fluorescence. Opposing sides of the catalytic domain engage spin-labeled membrane mimics. Loops project from the β-sheet interface to contact the phospholipid bilayer with basic and hydrophobic residues. The distal membrane interface comprises loops on the other side of the catalytic cleft. Both interfaces mediate MMP-12 association with vesicles and cell membranes. MMP-12 binds plasma membranes and is internalized to hydrophobic perinuclear features, the nuclear membrane, and inside the nucleus within minutes. While binding of TIMP-2 to MMP-12 hinders membrane interactions beside the active site, TIMP-2-inhibited MMP-12 binds vesicles and cells, suggesting compensatory rotation of its membrane approaches. MMP-12 association with diverse cell membranes may target its activities to modulate innate immune responses and inflammation. PMID:25412686

  1. Ambidextrous binding of cell and membrane bilayers by soluble matrix metalloproteinase-12.

    PubMed

    Koppisetti, Rama K; Fulcher, Yan G; Jurkevich, Alexander; Prior, Stephen H; Xu, Jia; Lenoir, Marc; Overduin, Michael; Van Doren, Steven R

    2014-01-01

    Matrix metalloproteinases (MMPs) regulate tissue remodelling, inflammation and disease progression. Some soluble MMPs are inexplicably active near cell surfaces. Here we demonstrate the binding of MMP-12 directly to bilayers and cellular membranes using paramagnetic NMR and fluorescence. Opposing sides of the catalytic domain engage spin-labelled membrane mimics. Loops project from the β-sheet interface to contact the phospholipid bilayer with basic and hydrophobic residues. The distal membrane interface comprises loops on the other side of the catalytic cleft. Both interfaces mediate MMP-12 association with vesicles and cell membranes. MMP-12 binds plasma membranes and is internalized to hydrophobic perinuclear features, the nuclear membrane and inside the nucleus within minutes. While binding of TIMP-2 to MMP-12 hinders membrane interactions beside the active site, TIMP-2-inhibited MMP-12 binds vesicles and cells, suggesting compensatory rotation of its membrane approaches. MMP-12 association with diverse cell membranes may target its activities to modulate innate immune responses and inflammation. PMID:25412686

  2. Expression and purification of integral membrane metallopeptidase HtpX.

    PubMed

    Arolas, Joan L; García-Castellanos, Raquel; Goulas, Theodoros; Akiyama, Yoshinori; Gomis-Rüth, F Xavier

    2014-07-01

    Little is known about the catalytic mechanism of integral membrane (IM) peptidases. HtpX is an IM metallopeptidase that plays a central role in protein quality control by preventing the accumulation of misfolded proteins in the membrane. Here we report the recombinant overexpression and purification of a catalytically ablated form of HtpX from Escherichia coli. Several E. coli strains, expression vectors, detergents, and purification strategies were tested to achieve maximum yields of pure and well-folded protein. HtpX was successfully overexpressed in E. coli BL21(DE3) cells using a pET-derived vector attaching a C-terminal His8-tag, extracted from the membranes using octyl-β-d-glucoside, and purified to homogeneity in the presence of this detergent in three consecutive steps: cobalt-affinity, anion-exchange, and size-exclusion chromatography. The production of HtpX in milligram amounts paves the way for structural studies, which will be essential to understand the catalytic mechanism of this IM peptidase and related family members. PMID:24769134

  3. Quantifying defects in zeolites and zeolite membranes

    NASA Astrophysics Data System (ADS)

    Hammond, Karl Daniel

    Zeolites are crystalline aluminosilicates that are frequently used as catalysts to transform chemical feedstocks into more useful materials in a size- or shape-selective fashion; they are one of the earliest forms of nanotechnology. Zeolites can also be used, especially in the form of zeolite membranes (layers of zeolite on a support), to separate mixtures based on the size of the molecules. Recent advances have also created the possibility of using zeolites as alkaline catalysts, in addition to their traditional applications as acid catalysts and catalytic supports. Transport and catalysis in zeolites are greatly affected by physical and chemical defects. Such defects can be undesirable (in the case of zeolite membranes), or desirable (in the case of nitrogen-doped alkaline zeolites). Studying zeolites at the relevant length scales requires indirect experimental methods such as vapor adsorption or atomic-scale modeling such as electronic structure calculations. This dissertation explores both experimental and theoretical characterization of zeolites and zeolite membranes. Physical defects, important in membrane permeation, are studied using physical adsorption experiments and models of membrane transport. The results indicate that zeolite membranes can be modeled as a zeolite powder on top of a support---a "supported powder," so to speak---for the purposes of adsorption. Mesoporosity that might be expected based on permeation and confocal microscopy measurements is not observed. Chemical defects---substitutions of nitrogen for oxygen---are studied using quantum mechanical models that predict spectroscopic properties. These models provide a method for simulating the 29Si NMR spectra of nitrogendefected zeolites. They also demonstrate that nitrogen substitutes into the zeolite framework (not just on the surface) under the proper reaction conditions. The results of these studies will be valuable to experimentalists and theorists alike in our efforts to understand the

  4. Energy efficiency in membrane bioreactors.

    PubMed

    Barillon, B; Martin Ruel, S; Langlais, C; Lazarova, V

    2013-01-01

    Energy consumption remains the key factor for the optimisation of the performance of membrane bioreactors (MBRs). This paper presents the results of the detailed energy audits of six full-scale MBRs operated by Suez Environnement in France, Spain and the USA based on on-site energy measurement and analysis of plant operation parameters and treatment performance. Specific energy consumption is compared for two different MBR configurations (flat sheet and hollow fibre membranes) and for plants with different design, loads and operation parameters. The aim of this project was to understand how the energy is consumed in MBR facilities and under which operating conditions, in order to finally provide guidelines and recommended practices for optimisation of MBR operation and design to reduce energy consumption and environmental impacts. PMID:23787304

  5. Materials for high-temperature catalytic combustion

    SciTech Connect

    Ramesh, K.S.; Cox, J.L.; Parks, W.P. Jr.

    1994-04-01

    Catalytic combustion systems for gas turbines must operate at temperatures of at least 1200{degrees}C. Support structure material must retain its integrity under prolonged exposure to high temperature, thermal cycling, and severe chemical conditions; and the material must be capable of being formed into thin sections. The performance requirements of a high-temperature stable ceramic support must be balanced with reasonable costs of preparation. An increasing number of materials have potential for successful exposure to high-temperature conditions. Two major problems of high-temperature catalyst systems are loss of surface area and catalytic activity. Incorporation of the catalytic component into the host lattice can circumvent this problem. Use of supporting active metal oxides on carrier materials with high thermal resistance appears to be a very promising way to make stable catalysts. The challenge will be to provide sufficient low-temperature activity and high-temperature stability; therefore, there exists a need to engineer catalytic materials for high-temperature combustion environments. Developments in catalytic materials and preparation procedures are reviewed. Future areas of research are discussed.

  6. 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.

  7. 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.

  8. 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.

  9. Ionene membrane battery separator

    NASA Technical Reports Server (NTRS)

    Moacanin, J.; Tom, H. Y.

    1969-01-01

    Ionic transport characteristics of ionenes, insoluble membranes from soluble polyelectrolyte compositions, are studied for possible application in a battery separator. Effectiveness of the thin film of separator membrane essentially determines battery lifetime.

  10. Composite zeolite membranes

    DOEpatents

    Nenoff, Tina M.; Thoma, Steven G.; Ashley, Carol S.; Reed, Scott T.

    2002-01-01

    A new class of composite zeolite membranes and synthesis techniques therefor has been invented. These membranes are essentially defect-free, and exhibit large levels of transmembrane flux and of chemical and isotopic selectivity.

  11. Hybrid adsorptive membrane reactor

    DOEpatents

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  12. Supertubes and Superconducting Membranes

    SciTech Connect

    Cordero, Ruben; Miguel-Pilar, Zelin

    2007-02-09

    We show the equivalence between configurations that arise from string theory of type IIA, called supertubes, and superconducting membranes at the bosonic level. We find equilibrium and oscillating configurations for a tubular membrane carrying a current along its axis.

  13. Premature rupture of membranes

    MedlinePlus

    ... When the water breaks early, it is called premature rupture of membranes (PROM). Most women will go ... th week of pregnancy, it is called preterm premature rupture of membranes (PPROM). The earlier your water ...

  14. Hybrid adsorptive membrane reactor

    NASA Technical Reports Server (NTRS)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  15. Supported inorganic membranes

    DOEpatents

    Sehgal, Rakesh; Brinker, Charles Jeffrey

    1998-01-01

    Supported inorganic membranes capable of molecular sieving, and methods for their production, are provided. The subject membranes exhibit high flux and high selectivity. The subject membranes are substantially defect free and less than about 100 nm thick. The pores of the subject membranes have an average critical pore radius of less than about 5 .ANG., and have a narrow pore size distribution. The subject membranes are prepared by coating a porous substrate with a polymeric sol, preferably under conditions of low relative pressure of the liquid constituents of the sol. The coated substrate is dried and calcined to produce the subject supported membrane. Also provided are methods of derivatizing the surface of supported inorganic membranes with metal alkoxides. The subject membranes find use in a variety of applications, such as the separation of constituents of gaseous streams, as catalysts and catalyst supports, and the like.

  16. Final Report

    SciTech Connect

    DeTar, Carleton

    2012-12-10

    This document constitutes the Final Report for award DE-FC02-06ER41446 as required by the Office of Science. It summarizes accomplishments and provides copies of scientific publications with significant contribution from this award.

  17. Final Report

    SciTech Connect

    Gurney, Kevin R

    2015-01-12

    This document constitutes the final report under DOE grant DE-FG-08ER64649. The organization of this document is as follows: first, I will review the original scope of the proposed research. Second, I will present the current draft of a paper nearing submission to Nature Climate Change on the initial results of this funded effort. Finally, I will present the last phase of the research under this grant which has supported a Ph.D. student. To that end, I will present the graduate student’s proposed research, a portion of which is completed and reflected in the paper nearing submission. This final work phase will be completed in the next 12 months. This final workphase will likely result in 1-2 additional publications and we consider the results (as exemplified by the current paper) high quality. The continuing results will acknowledge the funding provided by DOE grant DE-FG-08ER64649.

  18. Structure of the ATP Synthase Catalytic Complex (F1) from Escherichia coli in an Autoinhibited conformation

    SciTech Connect

    G Cingolani; T Duncan

    2011-12-31

    ATP synthase is a membrane-bound rotary motor enzyme that is critical for cellular energy metabolism in all kingdoms of life. Despite conservation of its basic structure and function, autoinhibition by one of its rotary stalk subunits occurs in bacteria and chloroplasts but not in mitochondria. The crystal structure of the ATP synthase catalytic complex (F{sub 1}) from Escherichia coli described here reveals the structural basis for this inhibition. The C-terminal domain of subunit {var_epsilon} adopts a heretofore unknown, highly extended conformation that inserts deeply into the central cavity of the enzyme and engages both rotor and stator subunits in extensive contacts that are incompatible with functional rotation. As a result, the three catalytic subunits are stabilized in a set of conformations and rotational positions distinct from previous F{sub 1} structures.

  19. Investigation of aligned carbon nanotubes as a novel catalytic electrodes for PEM fuel cells.

    SciTech Connect

    Liu, D. J.; Yang, J.; Gosztola, D. J.

    2007-01-01

    Recent progress in synthesizing and characterizing aligned carbon nanotubes (ACNT) as the electrode catalyst material for proton exchange membrane fuel cells (PEMFC) is reported. Catalytically functionalized ACNT active towards the electrocatalytic reduction of oxygen were prepared by a chemical vapor deposition method. The electrocatalytic activities and the nanostructures of the ACNT layers were investigated by cyclic voltammetry and scanning electron microscopy. To understand the nature of the transition metal as the catalytically active site in the ACNT, we also conducted an in situ X-ray absorption spectroscopic investigation at the Advanced Photon Source at Argonne National Laboratory. The oxidation state and coordination structure of the transition metals embedded inside the nanotubes were monitored by examining the EXAFS spectra collected under different polarization potentials. We clearly observed the change in the electronic and coordinational structures during the oxygen reduction reaction.

  20. Composite fuel cell membranes

    DOEpatents

    Plowman, Keith R.; Rehg, Timothy J.; Davis, Larry W.; Carl, William P.; Cisar, Alan J.; Eastland, Charles S.

    1997-01-01

    A bilayer or trilayer composite ion exchange membrane suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

  1. Composite fuel cell membranes

    DOEpatents

    Plowman, K.R.; Rehg, T.J.; Davis, L.W.; Carl, W.P.; Cisar, A.J.; Eastland, C.S.

    1997-08-05

    A bilayer or trilayer composite ion exchange membrane is described suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

  2. A Mechanistic Study of Chemically Modified Inorganic Membranes for Gas and Liquid Separations

    SciTech Connect

    Way, J Douglas

    2011-01-21

    This final report will summarize the progress made during the period August 1, 1993 - October 31, 2010 with support from DOE grant number DE-FG03-93ER14363. The objectives of the research have been to investigate the transport mechanisms in micro- and mesoporous, metal oxide membranes and to examine the relationship between the microstructure of the membrane, the membrane surface chemistry, and the separation performance of the membrane. Examples of the membrane materials under investigation are the microporous silica hollow fiber membrane manufactured by PPG Industries, chemically modified mesoporous oxide membranes, and polymer membranes containing microporous oxides (mixed matrix membranes). Analytical techniques such as NMR, FTIR and Raman spectroscopy, thermal analysis, and gas adsorption were used to investigate membrane microstructure and to probe the chemical interactions occurring at the gas-membrane interface.

  3. Meniscus membranes for separations

    DOEpatents

    Dye, Robert C.; Jorgensen, Betty; Pesiri, David R.

    2004-01-27

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  4. Meniscus Membranes For Separation

    DOEpatents

    Dye, Robert C.; Jorgensen, Betty; Pesiri, David R.

    2005-09-20

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  5. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1992-07-07

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  6. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1991-10-22

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  7. Polyphosphazene semipermeable membranes

    DOEpatents

    Allen, Charles A.; McCaffrey, Robert R.; Cummings, Daniel G.; Grey, Alan E.; Jessup, Janine S.; McAtee, Richard E.

    1988-01-01

    A semipermeable, inorganic membrane is disclosed; the membrane is prepared from a phosphazene polymer and, by the selective substitution of the constituent groups bound to the phosphorous in the polymer structure, the selective passage of fluid from a feedstream can be controlled. Resistance to high temperatures and harsh chemical environments is observed in the use of the phosphazene polymers as semipermeable membranes.

  8. Water vapor diffusion membranes

    NASA Technical Reports Server (NTRS)

    Holland, F. F., Jr.; Smith, J. K.

    1974-01-01

    The program is reported, which was designed to define the membrane technology of the vapor diffusion water recovery process and to test this technology using commercially available or experimental membranes. One membrane was selected, on the basis of the defined technology, and was subjected to a 30-day demonstration trial.

  9. Versatile Membrane Deformation Potential of Activated Pacsin

    PubMed Central

    Byrnes, Laura J.; Sondermann, Holger

    2012-01-01

    Endocytosis is a fundamental process in signaling and membrane trafficking. The formation of vesicles at the plasma membrane is mediated by the G protein dynamin that catalyzes the final fission step, the actin cytoskeleton, and proteins that sense or induce membrane curvature. One such protein, the F-BAR domain-containing protein pacsin, contributes to this process and has been shown to induce a spectrum of membrane morphologies, including tubules and tube constrictions in vitro. Full-length pacsin isoform 1 (pacsin-1) has reduced activity compared to its isolated F-BAR domain, implicating an inhibitory role for its C-terminal Src homology 3 (SH3) domain. Here we show that the autoinhibitory, intramolecular interactions in pacsin-1 can be released upon binding to the entire proline-rich domain (PRD) of dynamin-1, resulting in potent membrane deformation activity that is distinct from the isolated F-BAR domain. Most strikingly, we observe the generation of small, homogenous vesicles with the activated protein complex under certain experimental conditions. In addition, liposomes prepared with different methods yield distinct membrane deformation morphologies of BAR domain proteins and apparent activation barriers to pacsin-1's activity. Theoretical free energy calculations suggest bimodality of the protein-membrane system as a possible source for the different outcomes, which could account for the coexistence of energetically equivalent membrane structures induced by BAR domain-containing proteins in vitro. Taken together, our results suggest a versatile role for pacsin-1 in sculpting cellular membranes that is likely dependent both on protein structure and membrane properties. PMID:23236520

  10. 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).

  11. Controlling the catalytic aerobic oxidation of phenols.

    PubMed

    Esguerra, Kenneth Virgel N; Fall, Yacoub; Petitjean, Laurène; Lumb, Jean-Philip

    2014-05-28

    The oxidation of phenols is the subject of extensive investigation, but there are few catalytic aerobic examples that are chemo- and regioselective. Here we describe conditions for the ortho-oxygenation or oxidative coupling of phenols under copper (Cu)-catalyzed aerobic conditions that give rise to ortho-quinones, biphenols or benzoxepines. We demonstrate that each product class can be accessed selectively by the appropriate choice of Cu(I) salt, amine ligand, desiccant and reaction temperature. In addition, we evaluate the effects of substituents on the phenol and demonstrate their influence on selectivity between ortho-oxygenation and oxidative coupling pathways. These results create an important precedent of catalyst control in the catalytic aerobic oxidation of phenols and set the stage for future development of catalytic systems and mechanistic investigations. PMID:24784319

  12. Xylan-Degrading Catalytic Flagellar Nanorods.

    PubMed

    Klein, Ágnes; Szabó, Veronika; Kovács, Mátyás; Patkó, Dániel; Tóth, Balázs; Vonderviszt, Ferenc

    2015-09-01

    Flagellin, the main component of flagellar filaments, is a protein possessing polymerization ability. In this work, a novel fusion construct of xylanase A from B. subtilis and Salmonella flagellin was created which is applicable to build xylan-degrading catalytic nanorods of high stability. The FliC-XynA chimera when overexpressed in a flagellin deficient Salmonella host strain was secreted into the culture medium by the flagellum-specific export machinery allowing easy purification. Filamentous assemblies displaying high surface density of catalytic sites were produced by ammonium sulfate-induced polymerization. FliC-XynA nanorods were resistant to proteolytic degradation and preserved their enzymatic activity for a long period of time. Furnishing enzymes with self-assembling ability to build catalytic nanorods offers a promising alternative approach to enzyme immobilization onto nanostructured synthetic scaffolds. PMID:25966869

  13. The catalytic core of RNase P.

    PubMed Central

    Green, C J; Rivera-León, R; Vold, B S

    1996-01-01

    A deletion mutant of the catalytic RNA component of Escherichia coli RNase P missing residues 87-241 retains the ability to interact with the protein component to form a functional catalyst. The deletion of this phylogenetically conserved region significantly increases the Km, indicating that the deleted structures may be important for binding to the precursor tRNA substrate but not for the cleavage reaction. Under some reaction conditions, this RNase P deletion mutant can become a relatively non-specific nuclease, indicating that this RNA's catalytic center may be more exposed. The catalytic core of the RNase P is formed by less than one third of the 377 residues of the RNase P RNA. PMID:8628683

  14. 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}.

  15. ADAR proteins: structure and catalytic mechanism.

    PubMed

    Goodman, Rena A; Macbeth, Mark R; Beal, Peter A

    2012-01-01

    Since the discovery of the adenosine deaminase (ADA) acting on RNA (ADAR) family of proteins in 1988 (Bass and Weintraub, Cell 55:1089-1098, 1988) (Wagner et al. Proc Natl Acad Sci U S A 86:2647-2651, 1989), we have learned much about their structure and catalytic mechanism. However, much about these enzymes is still unknown, particularly regarding the selective recognition and processing of specific adenosines within substrate RNAs. While a crystal structure of the catalytic domain of human ADAR2 has been solved, we still lack structural data for an ADAR catalytic domain bound to RNA, and we lack any structural data for other ADARs. However, by analyzing the structural data that is available along with similarities to other deaminases, mutagenesis and other biochemical experiments, we have been able to advance the understanding of how these fascinating enzymes function. PMID:21769729

  16. Temperature Modulation of a Catalytic Gas Sensor

    PubMed Central

    Brauns, Eike; Morsbach, Eva; Kunz, Sebastian; Baeumer, Marcus; Lang, Walter

    2014-01-01

    The use of catalytic gas sensors usually offers low selectivity, only based on their different sensitivities for various gases due to their different heats of reaction. Furthermore, the identification of the gas present is not possible, which leads to possible misinterpretation of the sensor signals. The use of micro-machined catalytic gas sensors offers great advantages regarding the response time, which allows advanced analysis of the sensor response. By using temperature modulation, additional information about the gas characteristics can be measured and drift effects caused by material shifting or environmental temperature changes can be avoided. In this work a miniaturized catalytic gas sensor which offers a very short response time (<150 ms) was developed. Operation with modulated temperature allows analysis of the signal spectrum with advanced information content, based on the Arrhenius approach. Therefore, a high-precise electronic device was developed, since theory shows that harmonics induced by the electronics must be avoided to generate a comprehensible signal. PMID:25356643

  17. 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.

  18. 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

  19. Final Report - Advanced MEA's for Enhanced Operating Conditions, Amenable to High Volume Manufacture

    SciTech Connect

    Debe, Mark K.

    2007-09-30

    This report summarizes the work completed under a 3M/DOE contract directed at advancing the key fuel cell (FC) components most critical for overcoming the polymer electrolyte membrane fuel cell (PEMFC) performance, durability & cost barriers. This contract focused on the development of advanced ion exchange membranes & electrocatalysts for PEMFCs that will enable operation under ever more demanding automotive operating conditions & the use high volume compatible processes for their manufacture. Higher performing & more durable electrocatalysts must be developed for PEMFCs to meet the power density & lifetime hours required for FC vehicles. At the same time the amount of expensive Pt catalyst must be reduced to lower the MEA costs. While these two properties are met, the catalyst must be made resistant to multiple degradation mechanisms to reach necessary operating lifetimes. In this report, we present the work focused on the development of a completely new approach to PEMFC electrocatalyts, called nanostructured thin film (NSTF) catalysts. The carbon black supports are eliminated with this new approach which eliminates the carbon corrosion issue. The thin film nature of the catalyst significantly improves its robustness against dissolution & grain growth, preserving the surface area. Also, the activity of the NSTF for oxygen reduction is improved by over 500% compared to dispersed Pt catalyts. Finally, the process for fabricating the NSTF catalysts is consistent with high volume roll-good manufacturing & extremely flexible towards the introduction of new catalyst compositions & structures. This report documents the work done to develop new multi-element NSTF catalysts with properties that exceed pure Pt, that are optimized for use with the membranes discussed below, & advance the state-of-the-art towards meeting the DOE 2010 targets for PEMFC electrocatalysts. The work completed advances the understanding of the NSTF catalyst technology, identifies new NSTF

  20. High temperature ceramic membrane reactors for coal liquid upgrading

    SciTech Connect

    Tsotsis, T.T. . Dept. of Chemical Engineering); Liu, P.K.T. ); Webster, I.A. )

    1992-01-01

    Membrane reactors are today finding extensive applications for gas and vapor phase catalytic reactions (see discussion in the introduction and recent reviews by Armor [92], Hsieh [93] and Tsotsis et al. [941]). There have not been any published reports, however, of their use in high pressure and temperature liquid-phase applications. The idea to apply membrane reactor technology to coal liquid upgrading has resulted from a series of experimental investigations by our group of petroleum and coal asphaltene transport through model membranes. Coal liquids contain polycyclic aromatic compounds, which not only present potential difficulties in upgrading, storage and coprocessing, but are also bioactive. Direct coal liquefaction is perceived today as a two-stage process, which involves a first stage of thermal (or catalytic) dissolution of coal, followed by a second stage, in which the resulting products of the first stage are catalytically upgraded. Even in the presence of hydrogen, the oil products of the second stage are thought to equilibrate with the heavier (asphaltenic and preasphaltenic) components found in the feedstream. The possibility exists for this smaller molecular fraction to recondense with the unreacted heavy components and form even heavier undesirable components like char and coke. One way to diminish these regressive reactions is to selectively remove these smaller molecular weight fractions once they are formed and prior to recondensation. This can, at least in principle, be accomplished through the use of high temperature membrane reactors, using ceramic membranes which are permselective for the desired products of the coal liquid upgrading process. An additional incentive to do so is in order to eliminate the further hydrogenation and hydrocracking of liquid products to undesirable light gases.

  1. Catalytically solid-phase self-organization of nanoporous SnS with optical depolarizability.

    PubMed

    Cheng, Chih-Hsien; Chi, Yu-Chieh; Wu, Chung-Lun; Lin, Chun-Jung; Tsai, Ling-Hsuan; Chang, Jung-Hung; Chen, Mu Ku; Shih, Min-Hsiung; Lee, Chao-Kuei; Wu, Chih-I; Tsai, Din Ping; Lin, Gong-Ru

    2016-02-28

    The catalytic solid-phase synthesis of self-organized nanoporous tin sulfide (SnS) with enhanced absorption, manipulative transmittance and depolarization features is demonstrated. Using an ultralow radio-frequency (RF) sputtering power, the variation of the orientation angle between the anodized aluminum oxide (AAO) membrane and the axis of the sputtered ion beam detunes the catalytically synthesized SnS from nanorod to nanoporous morphology, along the sidewall of the AAO membrane. The ultraslow catalytic sputtering synthesis on the AAO at the RF plasma power of 20 W and the orientation angle of 0° regulates the porosity and integrality of nanoporous SnS, with average pore diameter of 80-150 nm. When transferring from planar to nanoporous structure, the phase composition changes from SnS to SnS2-Sn2S3, and the optical bandgap shrinks from 1.43 to 1.16 eV, due to the preferred crystalline orientation, which also contributes to an ultralow reflectance of <1% at 200-500 nm when both the transmittance and the surface scattering remain at their maxima. The absorption coefficient is enhanced by nearly one order of magnitude with its minimum of >5 × 10(4) cm(-1) at the wavelength between 200 and 700 nm, due to the red-shifting of the absorption spectrum to at least 100 nm. The catalytically self-organized nanoporous SnS causes strong haze and beam divergence of 20°-30° by depolarized nonlinear scattering at the surface, which favors the solar energy conversion with reduced surface reflection and enhanced photon scattering under preserved transmittance. PMID:26842460

  2. Catalytically solid-phase self-organization of nanoporous SnS with optical depolarizability

    NASA Astrophysics Data System (ADS)

    Cheng, Chih-Hsien; Chi, Yu-Chieh; Wu, Chung-Lun; Lin, Chun-Jung; Tsai, Ling-Hsuan; Chang, Jung-Hung; Chen, Mu Ku; Shih, Min-Hsiung; Lee, Chao-Kuei; Wu, Chih-I.; Tsai, Din Ping; Lin, Gong-Ru

    2016-02-01

    The catalytic solid-phase synthesis of self-organized nanoporous tin sulfide (SnS) with enhanced absorption, manipulative transmittance and depolarization features is demonstrated. Using an ultralow radio-frequency (RF) sputtering power, the variation of the orientation angle between the anodized aluminum oxide (AAO) membrane and the axis of the sputtered ion beam detunes the catalytically synthesized SnS from nanorod to nanoporous morphology, along the sidewall of the AAO membrane. The ultraslow catalytic sputtering synthesis on the AAO at the RF plasma power of 20 W and the orientation angle of 0° regulates the porosity and integrality of nanoporous SnS, with average pore diameter of 80-150 nm. When transferring from planar to nanoporous structure, the phase composition changes from SnS to SnS2-Sn2S3, and the optical bandgap shrinks from 1.43 to 1.16 eV, due to the preferred crystalline orientation, which also contributes to an ultralow reflectance of <1% at 200-500 nm when both the transmittance and the surface scattering remain at their maxima. The absorption coefficient is enhanced by nearly one order of magnitude with its minimum of >5 × 104 cm-1 at the wavelength between 200 and 700 nm, due to the red-shifting of the absorption spectrum to at least 100 nm. The catalytically self-organized nanoporous SnS causes strong haze and beam divergence of 20°-30° by depolarized nonlinear scattering at the surface, which favors the solar energy conversion with reduced surface reflection and enhanced photon scattering under preserved transmittance.

  3. Femtosecond laser machining of electrospun membranes

    NASA Astrophysics Data System (ADS)

    Wu, Yiquan; Vorobyev, A. Y.; Clark, Robert L.; Guo, Chunlei

    2011-01-01

    We demonstrate that a femtosecond laser can be used to machine arbitrary patterns and pattern arrays into free-standing electrospun polycaprolactone (PCL) membranes. We also examine the influence of various laser irradiation settings on the final microstructure of electrospun membranes. A beam fluence of 0.6 J/cm2 is used to ablate holes in 100 μm thick PCL membranes. The machined holes have an average diameter of 436 μm and a center-to-center spacing of 1000 μm. Based on these results, the femtosecond ablation of electrospun membranes shows great potential for fabricating a variety of functional tissue scaffolds. This technique will advance scaffold design by providing the ability to rapidly tailor surface morphology, while minimizing and controlling the deformation of the electrospun fibers.

  4. Economics of vanadium redox flow battery membranes

    NASA Astrophysics Data System (ADS)

    Minke, Christine; Turek, Thomas

    2015-07-01

    The membrane is a key component of the vanadium redox flow battery (VRFB) in terms of electrochemical performance as well as costs. The standard material Nafion® is cost intensive and therefore several alternative materials are in the focus of research. In this paper a substantial analytical approach is presented in order to quantify bottom price limits for different types of membranes. An in-depth analysis of material and production cost allows statements concerning cost potentials of different ion exchange membranes (IEM) and nano filtration membranes (NFM). The final result reveals that expected costs of IEM and NFM at high production volumes differ by one order of magnitude. Moreover, an analysis of the current market situation is made to provide a framework for economic considerations at present.

  5. Modifications of the chemical structure of phenolics differentially affect physiological activities in pulvinar cells of Mimosa pudica L. I. Multimode effect on early membrane events.

    PubMed

    Rocher, Françoise; Dédaldéchamp, Fabienne; Saeedi, Saed; Fleurat-Lessard, Pierrette; Chollet, Jean-Francois; Roblin, Gabriel

    2014-11-01

    A study of the structure-activity relationship carried out on several benzoic acid-related phenolics indicates that this type of compounds hinders the osmocontractile reaction of pulvinar cells in the range of 0-100%. Tentatively, we tried to find a way that could explain this differential action. With this aim, the relationship between the inhibitory effect and important molecular physico-chemical parameters (namely lipophilicity and degree of dissociation) was drawn. In addition, the effect of a variety of these compounds was investigated on their capacity to modify the electrical transmembrane potential and induce modifications in proton fluxes. Finally, using plasma membrane vesicles purified from pulvinar tissues, we examined the effects of some selected compounds on the proton pump activity and catalytic activity of the plasma membrane H(+)-ATPase. Taken together, the results indicate that a modification of the molecular structure of phenolics may induce important variation in the activity of the compound on these early membrane events. Among the tested phenolics, salicylic acid (SA) and acetylsalicylic acid (ASA, aspirin) are of particuler note, as they showed atypical effects on the physiological processes studied. PMID:25306527

  6. Probing the Catalytic Mechanism of S-Ribosylhomocysteinase (LuxS) with Catalytic Intermediates and Substrate Analogues

    SciTech Connect

    Gopishetty, Bhaskar; Zhu, Jinge; Rajan, Rakhi; Sobczak, Adam J.; Wnuk, Stanislaw F.; Bell, Charles E.; Pei, Dehua

    2009-05-12

    S-Ribosylhomocysteinase (LuxS) cleaves the thioether bond in S-ribosylhomocysteine (SRH) to produce homocysteine (Hcys) and 4,5-dihydroxy-2,3-pentanedione (DPD), the precursor of the type II bacterial quorum sensing molecule (AI-2). The catalytic mechanism of LuxS comprises three distinct reaction steps. The first step involves carbonyl migration from the C1 carbon of ribose to C2 and the formation of a 2-ketone intermediate. The second step shifts the C=O group from the C2 to C3 position to produce a 3-ketone intermediate. In the final step, the 3-ketone intermediate undergoes a {beta}-elimination reaction resulting in the cleavage of the thioether bond. In this work, the 3-ketone intermediate was chemically synthesized and shown to be chemically and kinetically competent in the LuxS catalytic pathway. Substrate analogues halogenated at the C3 position of ribose were synthesized and reacted as time-dependent inhibitors of LuxS. The time dependence was caused by enzyme-catalyzed elimination of halide ions. Examination of the kinetics of halide release and decay of the 3-ketone intermediate catalyzed by wild-type and mutant LuxS enzymes revealed that Cys-84 is the general base responsible for proton abstraction in the three reaction steps, whereas Glu-57 likely facilitates substrate binding and proton transfer during catalysis.

  7. Understanding transport in model water desalination membranes

    NASA Astrophysics Data System (ADS)

    Chan, Edwin

    Polyamide based thin film composites represent the the state-of-the-art nanofiltration and reverse osmosis membranes used in water desalination. The performance of these membranes is enabled by the ultrathin (~100 nm) crosslinked polyamide film in facilitating the selective transport of water over salt ions. While these materials have been refined over the last several decades, understanding the relationships between polyamide structure and membrane performance remains a challenge because of the complex and heterogeneous nature of the polyamide film. In this contribution, we present our approach to addressing this challenge by studying the transport properties of model polyamide membranes synthesized via molecular layer-by-layer (mLbL) assembly. First, we demonstrate that mLbL can successfully construct polyamide membranes with well-defined nanoscale thickness and roughness using a variety of monomer formulations. Next, we present measurement tools for characterizing the network structure and transport of these model polyamide membranes. Specifically, we used X-ray and neutron scattering techniques to characterize their structure as well as a recently-developed indentation based poromechanics approach to extrapolate their water diffusion coefficient. Finally, we illustrate how these measurements can provide insight into the original problem by linking the key polyamide network properties, i.e. water-polyamide interaction parameter and characteristic network mesh size, to the membrane performance.

  8. Properties and performance of EUVL pellicle membranes

    NASA Astrophysics Data System (ADS)

    Gallagher, Emily E.; Vanpaemel, Johannes; Pollentier, Ivan; Zahedmanesh, Houman; Adelmann, Christoph; Huyghebaert, Cedric; Jonckheere, Rik; Lee, Jae Uk

    2015-10-01

    EUV mask protection during handling and exposure remains a challenge for high volume manufacturing using EUV scanners. A thin, transparent membrane can be mounted above the mask pattern so that any particle that falls onto the front of the mask is held out of focus and does not image. The fluoropolymer membranes that are compatible with 193nm lithography absorb too strongly at the 13.5nm EUV exposure wavelength to be considered. Initially, the industry planned to expose EUV masks without any pellicle; however, the time and cost of fabricating and qualifying an EUV mask is simply too high to risk decimating wafer yield each time a particle falls onto the mask pattern. Despite the challenges of identifying a membrane for EUV, the industry has returned to the pellicle concept for protection. EUVL pellicles have been in development for more than a decade and reasonable options exist. Meeting all pellicle requirements is difficult, so this type of risk-mitigation effort is needed to ensure that there is a viable high-volume manufacturing option. This paper first reviews the desired membrane properties for EUVL pellicles. Next, candidate materials are introduced based on reported properties and compatibility with fabrication. Finally a set of candidate membranes are fabricated. These membranes are screened using a simplified set of tests to assess their suitability as an EUV pellicle. EUV transmission, film stress, and film durability data are included. The results are presented along with general guidelines for pellicle membrane properties for EUV manufacturing.

  9. A premixed hydrogen/oxygen catalytic igniter

    NASA Technical Reports Server (NTRS)

    Green, James M.

    1989-01-01

    The catalytic ignition of hydrogen and oxygen propellants was studied using a premixing hydrogen/oxygen injector. The premixed injector was designed to eliminate problems associated with catalytic ignition caused by poor propellant mixing in the catalyst bed. Mixture ratio, mass flow rate, and propellant inlet temperature were varied parametrically in testing, and a pulse mode life test of the igniter was conducted. The results of the tests showed that the premixed injector eliminated flame flashback in the reactor and increased the life of the igniter significantly. The results of the experimental program and a comparison with data collected in a previous program are given.

  10. Catalytic Enantioselective Functionalization of Unactivated Terminal Alkenes.

    PubMed

    Coombs, John R; Morken, James P

    2016-02-18

    Terminal alkenes are readily available functional groups which appear in α-olefins produced by the chemical industry, and they appear in the products of many contemporary synthetic reactions. While the organic transformations that apply to alkenes are amongst the most studied reactions in all of chemical synthesis, the number of reactions that apply to nonactivated terminal alkenes in a catalytic enantioselective fashion is small in number. This Minireview highlights the cases where stereocontrol in catalytic reactions of 1-alkenes is high enough to be useful for asymmetric synthesis. PMID:26764019

  11. Continuous in vitro evolution of catalytic function.

    PubMed

    Wright, M C; Joyce, G F

    1997-04-25

    A population of RNA molecules that catalyze the template-directed ligation of RNA substrates was made to evolve in a continuous manner in the test tube. A simple serial transfer procedure was used to achieve approximately 300 successive rounds of catalysis and selective amplification in 52 hours. During this time, the population size was maintained against an overall dilution of 3 x 10(298). Both the catalytic rate and amplification rate of the RNAs improved substantially as a consequence of mutations that accumulated during the evolution process. Continuous in vitro evolution makes it possible to maintain laboratory "cultures" of catalytic molecules that can be perpetuated indefinitely. PMID:9110984

  12. Catalytic Wastewater Treatment Using Pillared Clays

    NASA Astrophysics Data System (ADS)

    Perathoner, Siglinda; Centi, Gabriele

    After introduction on the use of solid catalysts in wastewater treatment technologies, particularly advanced oxidation processes (AOPs), this review discussed the use of pillared clay (PILC) materials in three applications: (i) wet air catalytic oxidation (WACO), (ii) wet hydrogen peroxide catalytic oxidation (WHPCO) on Cu-PILC and Fe-PILC, and (iii) behavior of Ti-PILC and Fe-PILC in the photocatalytic or photo-Fenton conversion of pollutants. Literature data are critically analyzed to evidence the main direction to further investigate, in particularly with reference to the possible practical application of these technologies to treat industrial, municipal, or agro-food production wastewater.

  13. Continuous in vitro evolution of catalytic function

    NASA Technical Reports Server (NTRS)

    Wright, M. C.; Joyce, G. F.

    1997-01-01

    A population of RNA molecules that catalyze the template-directed ligation of RNA substrates was made to evolve in a continuous manner in the test tube. A simple serial transfer procedure was used to achieve approximately 300 successive rounds of catalysis and selective amplification in 52 hours. During this time, the population size was maintained against an overall dilution of 3 x 10(298). Both the catalytic rate and amplification rate of the RNAs improved substantially as a consequence of mutations that accumulated during the evolution process. Continuous in vitro evolution makes it possible to maintain laboratory "cultures" of catalytic molecules that can be perpetuated indefinitely.

  14. Janus droplet as a catalytic micromotor

    NASA Astrophysics Data System (ADS)

    Shklyaev, Sergey

    2015-06-01

    Self-propulsion of a Janus droplet in a solution of surfactant, which reacts on a half of a drop surface, is studied theoretically. The droplet acts as a catalytic motor creating a concentration gradient, which generates its surface-tension-driven motion; the self-propulsion speed is rather high, 60 μ \\text{m/s} and more. This catalytic motor has several advantages over other micromotors: simple manufacturing, easily attained neutral buoyancy. In contrast to a single-fluid droplet, which demonstrates a self-propulsion as a result of symmetry breaking instability, for the Janus one no stability threshold exists; hence, the droplet radius can be scaled down to micrometers.

  15. Final Report

    SciTech Connect

    White, John M.

    2007-04-24

    Under our grant, DE-FG02-03ER15480, "Early transition metal oxides as catalysts: crossing scales from clusters to single crystals to functioning materials," catalytic activity of high surface area, powdered transition metal oxides (TMO, e.g. vanadium, niobium, molybdenum, and tungsten) supported on Al2O3, SiO2, ZrO2 and TiO2 have been extensively studied. In contrast, virtually no studies have been conducted for TMOs supported on well-ordered, single-crystalline oxides. This is largely due to a number of experimental difficulties related to the preparation of well-ordered oxide surfaces and to the charging problems associated with electron based probes on insulators. In our experiments we have selected TiO2(110) as a well-ordered substrate. TiO2(110) is a semiconductor (EG = 3.0 eV) and as such it has been extensively studied using ensemble averaged, as well as atomically resolved probes.1 In this work our goal was to create a well characterized, WO3/TiO2(110) model catalyst and interrogate its chemical activity for reactions of interest to this program. Initial studies of the chemical activity of the WO3 clusters on TiO2(110) focused on the partial oxidation of CH3OH. Only molecular desorption of CH3OH was observed. For 1 ML of CH3OH adsorbed on clean TiO2(110), the fraction of CH3OH desorbing from Ti4+ (250-400K) and BBO (150-250 K) sites is approximately the same, similar to H2O desorption. For CH3OH desorption from WO3/TiO2(110), a larger fraction of CH3OH desorbs from oxygen terminated sites, suggesting that the Ti4+ sites were covered by WO3. Current studies of alcohol oxidation reactions focus on the higher alcohols, such as 2-propanol and 2?butanol. In other studies, we have explored the adsorption of formaldehyde as one of the potential products in the partial oxidation of CH3OH. A catalytic polymerization reaction resulting in the formation of trioxane (paraformaldehyde) was observed.

  16. Tracking Membrane Protein Association in Model Membranes

    PubMed Central

    Reffay, Myriam; Gambin, Yann; Benabdelhak, Houssain; Phan, Gilles; Taulier, Nicolas; Ducruix, Arnaud; Hodges, Robert S.; Urbach, Wladimir

    2009-01-01

    Membrane proteins are essential in the exchange processes of cells. In spite of great breakthrough in soluble proteins studies, membrane proteins structures, functions and interactions are still a challenge because of the difficulties related to their hydrophobic properties. Most of the experiments are performed with detergent-solubilized membrane proteins. However widely used micellar systems are far from the biological two-dimensions membrane. The development of new biomimetic membrane systems is fundamental to tackle this issue. We present an original approach that combines the Fluorescence Recovery After fringe Pattern Photobleaching technique and the use of a versatile sponge phase that makes it possible to extract crucial informations about interactions between membrane proteins embedded in the bilayers of a sponge phase. The clear advantage lies in the ability to adjust at will the spacing between two adjacent bilayers. When the membranes are far apart, the only possible interactions occur laterally between proteins embedded within the same bilayer, whereas when membranes get closer to each other, interactions between proteins embedded in facing membranes may occur as well. After validating our approach on the streptavidin-biotinylated peptide complex, we study the interactions between two membrane proteins, MexA and OprM, from a Pseudomonas aeruginosa efflux pump. The mode of interaction, the size of the protein complex and its potential stoichiometry are determined. In particular, we demonstrate that: MexA is effectively embedded in the bilayer; MexA and OprM do not interact laterally but can form a complex if they are embedded in opposite bilayers; the population of bound proteins is at its maximum for bilayers separated by a distance of about 200 Å, which is the periplasmic thickness of Pseudomonas aeruginosa. We also show that the MexA-OprM association is enhanced when the position and orientation of the protein is restricted by the bilayers. We

  17. Elastic membranes in confinement

    NASA Astrophysics Data System (ADS)

    Bostwick, Joshua; Miksis, Michael; Davis, Stephen

    2014-11-01

    An elastic membrane stretched between two walls takes a shape defined by its length and the volume of fluid it encloses. Many biological structures, such as cells, mitochondria and DNA, have finer internal structure in which a membrane (or elastic member) is geometrically ``confined'' by another object. We study the shape stability of elastic membranes in a ``confining'' box and introduce repulsive van der Waals forces to prevent the membrane from intersecting the wall. We aim to define the parameter space associated with mitochondria-like deformations. We compare the confined to `unconfined' solutions and show how the structure and stability of the membrane shapes changes with the system parameters.

  18. Separation membrane development

    SciTech Connect

    Lee, M.W.

    1998-08-01

    A ceramic membrane has been developed to separate hydrogen from other gases. The method used is a sol-gel process. A thin layer of dense ceramic material is coated on a coarse ceramic filter substrate. The pore size distribution in the thin layer is controlled by a densification of the coating materials by heat treatment. The membrane has been tested by permeation measurement of the hydrogen and other gases. Selectivity of the membrane has been achieved to separate hydrogen from carbon monoxide. The permeation rate of hydrogen through the ceramic membrane was about 20 times larger than Pd-Ag membrane.

  19. Potential scorpionate antibiotics: targeted hydrolysis of lipid II containing model membranes by vancomycin-TACzyme conjugates and modulation of their antibacterial activity by Zn-ions.

    PubMed

    Bauke Albada, H; Arnusch, Christopher J; Branderhorst, Hilbert M; Verel, Anne-Marie; Janssen, Wouter T M; Breukink, Eefjan; de Kruijff, Ben; Pieters, Roland J; Liskamp, Rob M J

    2009-07-15

    The antibiotic vancomycin-that binds lipid II in the bacterial cell membrane-was conjugated to a mono- and tetravalent mimic of the tris-histidine catalytic triad of metalloenzymes. Targeted hydrolysis by the conjugate was observed using model membranes containing lipid II, and in vitro MIC-values of the targeted mimic constructs could be modulated by Zn-ions. PMID:19524434

  20. Membrane Flotation Assay

    PubMed Central

    Vogt, Dorothee A; Ott, Melanie

    2016-01-01

    Many postitive-stranded RNA viruses, such as Hepatitis C virus (HCV), highjack cellular membranes, including the Golgi, ER, mitchondria, lipid droplets, and utilize them for replication of their RNA genome or assembly of new virions. By investigating how viral proteins associate with cellular membranes we will better understand the roles of cellular membranes in the viral life cycle. Our lab has focused specifically on the role of lipid droplets and lipid-rich membranes in the life cycle of HCV. To analyze the role of lipid-rich membranes in HCV RNA replication, we utilized a membrane flotation assay based on an 10–20–30% iodixanol density gradient developed by Yeaman et al. (2001). This gradient results in a linear increase in density over almost the entire length of the gradient, and membrane particles are separated in the gradient based on their buoyant characteristics. To preserve membranes in the lysate, cells are broken mechanically in a buffer lacking detergent. The cell lysate is loaded on the bottom of the gradient, overlaid with the gradient, and membranes float up as the iodixanol gradient self-generates. The lipid content of membranes and the concentration of associated proteins will determine the separation of different membranes within the gradient. After centrifugation, fractions can be sampled from the top of the gradient and analyzed using standard SDS-PAGE and western blot analysis for proteins of interest.