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Sample records for adult microporous membrane

  1. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  2. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, M.A.; Guangyao Sheng.

    1993-05-04

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  3. Supported microporous ceramic membranes

    DOEpatents

    Webster, Elizabeth; Anderson, Marc

    1993-01-01

    A method for permformation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms.

  4. Supported microporous ceramic membranes

    DOEpatents

    Webster, E.; Anderson, M.

    1993-12-14

    A method for the formation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms. 4 figures.

  5. Denitrification incorporating microporous membranes

    SciTech Connect

    Reising, A.R.; Schroeder, E.D.

    1996-07-01

    A microbial system for removal of nitrate from drinking water in which the denitrification reactions are physically separated from the water being treated by a microporous membrane was studied. The experimental system was composed of two equal-volume cells separated by a 0.02 {mu}m pore size polytetrafluoroethylene membrane. No pressure difference existed across the membrane, and nitrate ions were transported through the membrane by diffusion. Results of experiments with biofilm denitrification and suspended-culture systems are presented. Deoxygenation by N{sub 2} stripping and by SO{sub 3}{sup {minus}2} produced equivalent results. Removal rates with the suspended culture systems were greater than those with biofilms. Effective membrane diffusivities calculated for suspended-culture systems were approximately the same as for sterile systems, indicating that resistance to transport was not changed by the addition of the suspended microbial culture. The methanol requirement observed in the experiments was 1.4 g total organic carbon (TOC) per g NO{sub 3}{sup {minus}}-N removed. Removal rates followed first-order pseudotransport controlled models for both the biofilm and suspended-culture systems. A prototype continuous-flow system is presented.

  6. Inorganic dual-layer microporous supported membranes

    DOEpatents

    Brinker, C. Jeffrey; Tsai, Chung-Yi; Lu, Yungfeng

    2003-03-25

    The present invention provides for a dual-layer inorganic microporous membrane capable of molecular sieving, and methods for production of the membranes. The inorganic microporous supported membrane includes a porous substrate which supports a first inorganic porous membrane having an average pore size of less than about 25 .ANG. and a second inorganic porous membrane coating the first inorganic membrane having an average pore size of less than about 6 .ANG.. The dual-layered membrane is produced by contacting the porous substrate with a surfactant-template polymeric sol, resulting in a surfactant sol coated membrane support. The surfactant sol coated membrane support is dried, producing a surfactant-templated polymer-coated substrate which is calcined to produce an intermediate layer surfactant-templated membrane. The intermediate layer surfactant-templated membrane is then contacted with a second polymeric sol producing a polymeric sol coated substrate which is dried producing an inorganic polymeric coated substrate. The inorganic polymeric coated substrate is then calcined producing an inorganic dual-layered microporous supported membrane in accordance with the present invention.

  7. Solvent-resistant microporous polymide membranes

    DOEpatents

    Miller, W.K.; McCray, S.B.; Friesen, D.T.

    1998-03-10

    An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

  8. Solvent-resistant microporous polymide membranes

    DOEpatents

    Miller, Warren K.; McCray, Scott B.; Friesen, Dwayne T.

    1998-01-01

    An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

  9. Method for making a microporous membrane

    NASA Technical Reports Server (NTRS)

    Gavalas, Lillian Susan (Inventor)

    2013-01-01

    A method for making a microporous membrane comprises the steps of: providing a plurality of carbon nanotubes having a hollow interior diameter of 20 Angstroms or less; sonicating the plurality of carbon nanotubes utilizing a solution comprising deionized, distilled water and a surfactant that coats at least one of the plurality of carbon nanotubes; collecting the coated carbon nanotubes; forming a matrix that supports the plurality of carbon nanotubes; embedding the coated carbon nanotubes into the matrix; rinsing the coated nanotubes to remove at least a portion of the surfactant; curing the nanotube-matrix assembly; and cutting the nanotube-matrix assembly to a particular thickness so as to open the ends of the embedded nanotubes. The hollow interiors of the plurality of embedded carbon nanotubes comprise the pores of the microporous membrane.

  10. Gas transmission through microporous membranes

    NASA Astrophysics Data System (ADS)

    Turel, Tacibaht

    2008-10-01

    An ideal protective clothing material should be a good barrier against harmful gases or vapor while allowing moisture vapor and air passage through the material. In the study and design of barrier materials, one of the critical issues is to balance these requirements, which may sometimes be mutually exclusive. Therefore it is critical to understand the macroscopic and microscopic structure of the attack mechanisms as well as the barrier materials and the transport phenomena in such systems. In this study, air and gas transmission through barrier systems consisting of porous membranes was investigated experimentally and a molecular-level probabilistic model was constructed to evaluate the effect of various parameters on the gas flow. The effect of membrane parameters such as porosity, pore size distribution, thickness as well as gas parameters such as molecule diameters were examined at single layer as well as multiple layers. To understand the gas behavior for harmful chemicals and to ensure safety during experimental studies, mimics of such gases were obtained which were comparable to the actual gases in shape, molecular weight and other chemical properties. Air, ammonia and several mimic gases of harmful chemical agents were studied. Beta-pinene was used as a mimic of sarin and prenol was used as a mimic of nitrogen mustard. Gas transmission experiments were conducted on polyester, nylon and polypropylene membranes each of which had different porosity and pore size distributions. Experiments were done at different pressure values and a comparison was made between permeability testing machines based on volumetric and manometric principles as to their ability to accommodate high permeability membranes. Physical and chemical adsorption of such gases on porous membranes was also investigated after the addition of active elements on the membrane surfaces which can interact with the gas molecules. An experimental setup was developed to measure concentration changes

  11. Hydrogenotrophic denitrification in a microporous membrane bioreactor.

    PubMed

    Mansell, Bruce O; Schroeder, Edward D

    2002-11-01

    Hydrogenotrophic denitrification of nitrate contaminated groundwater in a bench-scale microporous membrane bioreactor has been investigated. To prevent microbial contamination of the effluent from the reactor the nitrate-laden water treated was separated from the denitrifying culture with a 0.02 microm pore diameter membrane. Equal pressure was maintained across the membrane and nitrate was removed by molecular diffusion through the membrane and into the denitrifying culture. The system was operated with a hydrogenotrophic denitrification culture to circumvent the addition of an organic substrate to the water. Removal efficiencies ranging from 96% to 92% were achieved at influent concentrations ranging from 20 to 40 mg/L NO3(-)-N. The flux values achieved in this study were 2.7-5.3 g NO3-N m 2d(-1). The microporous membrane served as an effective barrier for preventing microbial contamination of the product water as evidenced by the effluent heterotrophic plate count of 9 (+/- 3.5) CFU/mL. The hydrogenotrophic culture was analyzed using available 16S and 23S rRNA-targeted oligonucleotide probes. It was determined that the enrichment process selected for organisms belonging to the beta subclass of Proteobacteria. Further analysis of the hydrogenotrophic culture indicated that the organisms may belong to the beta-3 subgroup of Proteobacteria and have yet to be identified as hydrogenotrophic denitrifiers.

  12. Functionalizing Microporous Membranes for Protein Purification and Protein Digestion

    NASA Astrophysics Data System (ADS)

    Dong, Jinlan; Bruening, Merlin L.

    2015-07-01

    This review examines advances in the functionalization of microporous membranes for protein purification and the development of protease-containing membranes for controlled protein digestion prior to mass spectrometry analysis. Recent studies confirm that membranes are superior to bead-based columns for rapid protein capture, presumably because convective mass transport in membrane pores rapidly brings proteins to binding sites. Modification of porous membranes with functional polymeric films or TiO2 nanoparticles yields materials that selectively capture species ranging from phosphopeptides to His-tagged proteins, and protein-binding capacities often exceed those of commercial beads. Thin membranes also provide a convenient framework for creating enzyme-containing reactors that afford control over residence times. With millisecond residence times, reactors with immobilized proteases limit protein digestion to increase sequence coverage in mass spectrometry analysis and facilitate elucidation of protein structures. This review emphasizes the advantages of membrane-based techniques and concludes with some challenges for their practical application.

  13. Characterization of microporous membranes using confocal scanning laser microscopy in fluorescence mode

    NASA Astrophysics Data System (ADS)

    Charcosset, C.; Bernengo, J.-C.

    2000-12-01

    Confocal Scanning Laser Microscopy (CSLM) in fluorescence mode was used to characterize microporous membranes. Two microfiltration membranes were investigated: a mixed ester (cellulose nitrate/cellulose acetate) 1.2 μm-rated membrane and a polycarbonate track-etched membrane with cylindrical pores of 2 μm diameter. Optical sections of the membranes stained with rhodamine and mounted in glycerol were performed at 1 μm intervals, from 0 to 10 μm. CSLM was found useful for microporous membrane characterization, as it gives some insight into bulk membrane morphology.

  14. Ion separations based on electrical potentials nanoporous and microporous membranes

    NASA Astrophysics Data System (ADS)

    Armstrong, Jason

    monovalent ions (e.g. Li+ and Cs+), via a streaming-potential mechanism. In these separations, flow through a negatively charged membrane yields a positive (permeate minus feed) streaming potential, which retards the transport of a more mobile cation to a greater extent than transport of a less mobile cation. Thus, (PSS)1-modified, 30-nm PCTE membranes enabled Li+ and Cs+ separation, whereas (PSS-PAH)1-modified membranes separated acetate- and Br-. Cation selectivities were ~3 for solutions containing 1.5 mM Li2SO 4 and 1.5 mM Cs2SO4, whereas anion selectivities were ~6 for 0.5 mM Mg(Acetate)2, 0.5 mM MgBr2. The streaming potential method gave only modest selectivities, however, and required low ion concentrations. Electrical potentials applied across microporous glass membranes also facilitate separation of monovalent ions with different electrophoretic mobilities. This dissertation describes a filtration cell with porous electrodes to enable cross-flow filtration with an applied potential. With the appropriate potentials, the cell afforded some separation of K+ and Li+, but the average selectivities were ~3. Moreover, the rejection of both ions plateaued near 90% at sufficiently high current to flow rate ratios. Buffer depletion or nonuniform cross-flow and electric fields may lead to membrane areas with low rejection and prevent high selectivities. Fabrication of a dual cross-flow cell (cross-flow on feed and permeate sides) limits buffer depletion issues and may provide higher monovalent ion selectivities.

  15. Nanowire-integrated microporous silicon membrane for continuous fluid transport in micro cooling device

    SciTech Connect

    So, Hongyun; Pisano, Albert P.; Cheng, Jim C.

    2013-10-14

    We report an efficient passive micro pump system combining the physical properties of nanowires and micropores. This nanowire-integrated microporous silicon membrane was created to feed coolant continuously onto the surface of the wick in a micro cooling device to ensure it remains hydrated and in case of dryout, allow for regeneration of the system. The membrane was fabricated by photoelectrochemical etching to form micropores followed by hydrothermal growth of nanowires. This study shows a promising approach to address thermal management challenges for next generation electronic devices with absence of external power.

  16. Comparison of microporous and nonporous membrane bioreactor systems for the treatment of BTEX in vapor streams.

    PubMed

    Attaway, H; Gooding, C H; Schmidt, M G

    2002-05-01

    Increased regulatory constraints on industrial releases of atmospheric volatile organic compounds (VOCs) have resulted in an interest in using biofilters, bioscrubbers and air/liquid membranes for treatment of vapor phase waste streams. In this report, we describe the comparison of the use of two fundamentally different types of membrane module systems that allow the rapid diffusion of vapor phase aromatics and oxygen to an active biofilm for subsequent biodegradation. One system used a commercial membrane module containing microporous polypropylene fibers while the other used a nonporous silicone tubing membrane module for the delivery of substrate (a mixture of benzene, ethylbenzene, toluene, and xylenes [BTEX]) and electron acceptor (O(2)). Tests of the systems under similar conditions with BTEX in the vapor feed stream showed significant performance advantages for the silicone membrane system. The average surface-area-based BTEX removal rate for the microporous membrane system over 500 h of operation was 7.88 microg h(-1) cm(-2) while the rate for the silicone membrane system was 23.87 microg h(-1) cm(-2). The percentages of BTEX removal were also consistently better in the silicone membrane system versus the microporous system. Part of the performance problem associated with the microporous membrane system appeared to be internal water condensation and possible plugging of the pores with biomass over time that could not be resolved with vapor phase backflushing. PMID:11986927

  17. Synthesis and characterization of microporous inorganic membranes for propylene/propane separation

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoli

    Membrane-based gas separation is promising for efficient propylene/propane (C3H6/C3H8) separation with low energy consumption and minimum environment impact. Two microporous inorganic membrane candidates, MFI-type zeolite membrane and carbon molecular sieve membrane (CMS) have demonstrated excellent thermal and chemical stability. Application of these membranes into C3H6/C3H 8 separation has not been well investigated. This dissertation presents fundamental studies on membrane synthesis, characterization and C3H 6/C3H8 separation properties of MFI zeolite membrane and CMS membrane. MFI zeolite membranes were synthesized on α-alumina supports by secondary growth method. Novel positron annihilation spectroscopy (PAS) techniques were used to non-destructively characterize the pore structure of these membranes. PAS reveals a bimodal pore structure consisting of intracrystalline zeolitic micropores of ~0.6 nm in diameter and irregular intercrystalline micropores of 1.4 to 1.8 nm in size for the membranes. The template-free synthesized membrane exhibited a high permeance but a low selectivity in C3H 6/C3H8 mixture separation. CMS membranes were synthesized by coating/pyrolysis method on mesoporous gamma-alumina support. Such supports allow coating of thin, high-quality polymer films and subsequent CMS membranes with no infiltration into support pores. The CMS membranes show strong molecular sieving effect, offering a high C3H 6/C3H8 mixture selectivity of ~30. Reduction in membrane thickness from 500 nm to 300 nm causes an increase in C3H8 permeance and He/N2 selectivity, but a decrease in the permeance of He, N 2 and C3H6 and C3H6/C 3H8 selectivity. This can be explained by the thickness dependent chain mobility of the polymer film resulting in final carbon membrane of reduced pore size with different effects on transport of gas of different sizes, including possible closure of C3H6-accessible micropores. CMS membranes demonstrate excellent C3H6/C 3H8 separation

  18. Towards high water permeability in triazine-framework-based microporous membranes for dehydration of ethanol.

    PubMed

    Tang, Yu Pan; Wang, Huan; Chung, Tai Shung

    2015-01-01

    The microstructural evolution of a series of triazine framework-based microporous (TFM) membranes under different conditions has been explored in this work. The pristine TFM membrane is in situ fabricated in the course of polymer synthesis via a facile Brønsted-acid-catalyzed cyclotrimerizaiton reaction. The as-synthesized polymer exhibits a microporous network with high thermal stability. The free volume size of the TFM membranes gradually evolved from a unimodal distribution to a bimodal distribution under annealing, as analyzed by positron annihilation lifetime spectroscopy (PALS). The emergence of the bimodal distribution is probably ascribed to the synergetic effect of quenching and thermal cyclization reaction. In addition, the fractional free volume (FFV) of the membranes presents a concave trend with increasing annealing temperature. Vapor sorption tests reveal that the mass transport properties are closely associated with the free volume evolution, which provides an optimal condition for dehydration of biofuels. A promising separation performance with extremely high water permeability has been attained for dehydration of an 85 wt % ethanol aqueous solution at 45 °C. The study on the free volume evolution of the TFM membranes may provide useful insights about the microstructure and mass transport behavior of the microporous polymeric materials.

  19. Removal of endotoxin from water by microfiltration through a microporous polyethylene hollow-fiber membrane

    SciTech Connect

    Sawada, Y.; Fujii, R.; Igami, I.; Kawai, A.; Kamiki, T.; Niwa, M.

    1986-04-01

    The microporous polyethylene hollow-fiber membrane has a unique microfibrile structure throughout its depth and has been found to possess the functions of filtration and adsorption of endotoxin in water. The membrane has a maximum pore diameter of approximately 0.04 micron, a diameter which is within the range of microfiltration. Approximately 10 and 20% of the endotoxin in tap water and subterranean water, respectively, was smaller than 0.025 micron. Endotoxin in these water sources was efficiently removed by the microporous polyethylene hollow-fiber membrane. Escherichia coli O113 culture broth contained 26.4% of endotoxin smaller than 0.025 micron which was also removed. Endotoxin was leaked into the filtrate only when endotoxin samples were successively passed through the membrane. These results indicate that endotoxin smaller than the pore size of the membrane was adsorbed and then leaked into the filtrate because of a reduction in binding sites. Dissociation of /sup 3/H-labeled endotoxin from the membrane was performed, resulting in the removal of endotoxin associated with the membrane by alcoholic alkali at 78% efficiency.

  20. Positively charged microporous ceramic membrane for the removal of Titan Yellow through electrostatic adsorption.

    PubMed

    Cheng, Xiuting; Li, Na; Zhu, Mengfu; Zhang, Lili; Deng, Yu; Deng, Cheng

    2016-06-01

    To develop a depth filter based on the electrostatic adsorption principle, positively charged microporous ceramic membrane was prepared from a diatomaceous earth ceramic membrane. The internal surface of the highly porous ceramic membrane was coated with uniformly distributed electropositive nano-Y2O3 coating. The dye removal performance was evaluated through pressurized filtration tests using Titan Yellow aqueous solution. It showed that positively charged microporous ceramic membrane exhibited a flow rate of 421L/(m(2)·hr) under the trans-membrane pressure of 0.03bar. Moreover it could effectively remove Titan Yellow with feed concentration of 10mg/L between pH3 to 8. The removal rate increased with the enhancement of the surface charge properties with a maximum rejection of 99.6%. This study provides a new and feasible method of removing organic dyes in wastewater. It is convinced that there will be a broad market for the application of charged ceramic membrane in the field of dye removal or recovery from industry wastewater. PMID:27266317

  1. Engineering Surface Energy and Nanostructure of Microporous Films for Expanded Membrane Distillation Applications.

    PubMed

    Boo, Chanhee; Lee, Jongho; Elimelech, Menachem

    2016-08-01

    We investigated the factors that determine surface omniphobicity of microporous membranes and evaluated the potential application of these membranes in desalination of low surface tension wastewaters by membrane distillation (MD). Specifically, the effects of surface morphology and surface energy on membrane surface omniphobicity were systematically investigated by evaluating wetting resistance to low surface tension liquids. Single and multilevel re-entrant structures were achieved by using cylindrical glass fibers as a membrane substrate and grafting silica nanoparticles (SiNPs) on the fibers. Surface energy of the membrane was tuned by functionalizing the fiber substrate with fluoroalkylsilane (FAS) having two different lengths of fluoroalkyl chains. Results show that surface omniphobicity of the modified fibrous membrane increased with higher level of re-entrant structure and with lower surface energy. The secondary re-entrant structure achieved by SiNP coating on the cylindrical fibers was found to play a critical role in enhancing the surface omniphobicity. Membranes coated with SiNPs and chemically modified by the FAS with a longer fluoroalkyl chain (or lower surface energy) exhibited excellent surface omniphobicity and showed wetting resistance to low surface tension liquids such as ethanol (22.1 mN m(-1)). We further evaluated performance of the membranes in desalination of saline feed solutions with varying surface tensions by membrane distillation (MD). The engineered membranes exhibited stable MD performance with low surface tension feed waters, demonstrating the potential application omniphobic membranes in desalinating complex, high salinity industrial wastewaters. PMID:27391088

  2. Engineering Surface Energy and Nanostructure of Microporous Films for Expanded Membrane Distillation Applications.

    PubMed

    Boo, Chanhee; Lee, Jongho; Elimelech, Menachem

    2016-08-01

    We investigated the factors that determine surface omniphobicity of microporous membranes and evaluated the potential application of these membranes in desalination of low surface tension wastewaters by membrane distillation (MD). Specifically, the effects of surface morphology and surface energy on membrane surface omniphobicity were systematically investigated by evaluating wetting resistance to low surface tension liquids. Single and multilevel re-entrant structures were achieved by using cylindrical glass fibers as a membrane substrate and grafting silica nanoparticles (SiNPs) on the fibers. Surface energy of the membrane was tuned by functionalizing the fiber substrate with fluoroalkylsilane (FAS) having two different lengths of fluoroalkyl chains. Results show that surface omniphobicity of the modified fibrous membrane increased with higher level of re-entrant structure and with lower surface energy. The secondary re-entrant structure achieved by SiNP coating on the cylindrical fibers was found to play a critical role in enhancing the surface omniphobicity. Membranes coated with SiNPs and chemically modified by the FAS with a longer fluoroalkyl chain (or lower surface energy) exhibited excellent surface omniphobicity and showed wetting resistance to low surface tension liquids such as ethanol (22.1 mN m(-1)). We further evaluated performance of the membranes in desalination of saline feed solutions with varying surface tensions by membrane distillation (MD). The engineered membranes exhibited stable MD performance with low surface tension feed waters, demonstrating the potential application omniphobic membranes in desalinating complex, high salinity industrial wastewaters.

  3. Preparation of uniform-sized agarose beads by microporous membrane emulsification technique.

    PubMed

    Zhou, Qing-Zhu; Wang, Lian-Yan; Ma, Guang-Hui; Su, Zhi-Guo

    2007-07-01

    Uniform-sized agarose beads were prepared by membrane emulsification technique in this study. Agarose was dissolved in boiling water (containing 0.9% sodium chloride) and used as water phase. A mixture of liquid paraffin and petroleum ether containing 4 wt% of hexaglycerin penta ester (PO-500) emulsifier was used as oil phase. At 55 degrees C, the water phase permeated through uniform pores of microporous membrane into the oil phase by a pressure of nitrogen gas to form uniform W/O emulsion. Then the emulsion was cooled down to room temperature under gentle agitation to form gel beads. The effect of oil phase, emulsifier, especially temperature on the uniformity of the beads were investigated and interpreted from interfacial tension between water phase and oil phase. Under optimized condition, the coefficient variation (C.V.) showing the size distribution of the beads was under 15%. This was the first report to prepare uniform agarose beads by membrane emulsification, and to investigate the effect of temperature on the size distribution of the droplets and beads. The beads with different size can be prepared by using membranes with different pore size, and the result showed that there was a linear relationship between the average diameter of beads and pore size of the membranes; beads with diameter from 15 to 60 microm were able to obtain in this study.

  4. Immobilization of L-lysine on microporous PVDF membranes for neuron culture.

    PubMed

    Young, Tai-Horng; Lin, Ui-Hsiang; Lin, Dar-Jong; Chang, Hsu-Hsien; Cheng, Liao-Ping

    2009-01-01

    Microporous poly(vinylidene fluoride) (PVDF) membranes with dense or porous surface were prepared by immersion precipitation of PVDF/TEP solutions in coagulation baths containing different amounts of water. Onto the membrane surface, poly(glycidyl methacrylate) (PGMA) was grafted by plasma-induced free radical polymerization. Then, L-lysine was covalently bonded to the as-grafted PGMA through ring-opening reactions between epoxide and amine to form amino alcohol. The highest attainable graft density of PGMA on a PVDF membrane was 0.293 mg/cm2. This was obtained when the reaction was carried out on a porous surface under an optimized reaction condition. For immobilization of L-lysine, the yield was found to depend on the reaction temperature and L-lysine concentration. The maximal yield was 0.226 mg/cm2, a value considerably higher than reported in the literature using other immobilization methods. Furthermore, neurons were cultured on L-lysine-immobilized PVDF membranes. The results indicated that these membrane surfaces were suited to the growth of neurons, with a MTT value higher than that of the standard culture dish. PMID:19323885

  5. Highly Conductive Anion-Exchange Membranes from Microporous Tröger's Base Polymers.

    PubMed

    Yang, Zhengjin; Guo, Rui; Malpass-Evans, Richard; Carta, Mariolino; McKeown, Neil B; Guiver, Michael D; Wu, Liang; Xu, Tongwen

    2016-09-12

    The development of polymeric anion-exchange membranes (AEMs) combining high ion conductivity and long-term stability is a major challenge for materials chemistry. AEMs with regularly distributed fixed cationic groups, based on the formation of microporous polymers containing the V-shape rigid Tröger's base units, are reported for the first time. Despite their simple preparation, which involves only two synthetic steps using commercially available precursors, the polymers provide AEMs with exceptional hydroxide conductivity at relatively low ion-exchange capacity, as well as a high swelling resistance and chemical stability. An unprecedented hydroxide conductivity of 164.4 mS cm(-1) is obtained at a relatively a low ion-exchange capacity of 0.82 mmol g(-1) under optimal operating conditions. The exceptional anion conductivity appears related to the intrinsic microporosity of the charged polymer matrix, which facilitates rapid anion transport. PMID:27505421

  6. Impact of polymer electrolyte membrane fuel cell microporous layer nano-scale features on thermal conductance

    NASA Astrophysics Data System (ADS)

    Botelho, S. J.; Bazylak, A.

    2015-04-01

    In this study, the microporous layer (MPL) of the polymer electrolyte membrane (PEM) fuel cell was analysed at the nano-scale. Atomic force microscopy (AFM) was utilized to image the top layer of MPL particles, and a curve fitting algorithm was used to determine the particle size and filling radius distributions for SGL-10BB and SGL-10BC. The particles in SGL-10BC (approximately 60 nm in diameter) have been found to be larger than those in SGL-10BB (approximately 40 nm in diameter), highlighting structural variability between the two materials. The impact of the MPL particle interactions on the effective thermal conductivity of the bulk MPL was analysed using a discretization of the Fourier equation with the Gauss-Seidel iterative method. It was found that the particle spacing and filling radius dominates the effective thermal conductivity, a result which provides valuable insight for future MPL design.

  7. Evaluation of a new microporous filtration membrane system for therapeutic plasma exchange.

    PubMed

    Kurtz, S R; Carey, P M; McGill, M; Pineda, A A; Zaroulis, C G; Case, M T

    1987-01-01

    A new therapeutic plasma exchange device developed by Sarns Inc./3M was evaluated in plasmapheresis of 20 healthy volunteers and in a multicenter clinical study of therapeutic plasma exchange that included 49 patients. Safety and efficacy of plasma separation from whole blood were assessed for a module that contains Durapore microporous surfactant-free polyvinylidene fluoride membrane (Millipore Corp., Bedford, Mass., USA). The extra-corporeal volume was 80 ml. Citrate and heparin anticoagulants were utilized. Mean plasma separation efficiency was 62% with unhindered passage of plasma proteins through the membrane pores and no hemolysis or activation of complement as measured by total hemolytic complement (CH50) and C3 conversion. Mean decrease in platelet count after procedures was 10%. No severe reactions occurred, and citrate effects (13%) were comparable to values reported with centrifugal instruments. The Sarns Inc./3M Therapore device is a rapid, safe and efficient system for plasma exchange and potentially for source plasma collection. The principal benefits are small extracorporeal volume and cell-free filtrate.

  8. Functional gold nanoparticles coupled with microporous membranes: a flow controlled assay for colorimetric visualization of proteins.

    PubMed

    Chen, Yu-Yuan; Unnikrishnan, Binesh; Li, Yu-Jia; Huang, Chih-Ching

    2014-11-21

    We report a rapid and simple assay for colorimetric visualization of thrombin at nanomolar levels using functional gold nanoparticles (FAuNPs) coupled with microporous membranes. We used a 29-mer thiolated-thrombin-binding-aptamer (TBA29) to prepare TBA29 functionalized AuNPs (TBA29-AuNPs) for the selective detection of human thrombin. The sensing mechanism is based on the principle of TBA29-AuNPs flowing down through the nitrocellulose membrane (NCM) pores at different flow rates after binding to thrombin. Compared with free TBA29-AuNPs, when thrombin-TBA29-AuNPs were dropped on the NCM, the particles flowed down more easily through the NCM pores along with the buffer solution due to the increase in the gravity of particles. Therefore, color intensities of TBA29-AuNPs on the NCM depended on the concentration of thrombin; the color intensity was lighter when the concentration of thrombin was higher. Thrombin can be detected at the nanomolar level with the naked eye using this colorimetric probe. A protein G modified AuNP based probe (PG-AuNPs/NCM) was employed to detect human immunoglobulin G (hIgG) in plasma samples to demonstrate the practicality of our sensing system. Also, fibrinogen modified Au NPs were analyzed to demonstrate that this concept of detection could be extended to other proteins or systems, by functionalizing with suitable molecules.

  9. Bio-electrochemical characterization of air-cathode microbial fuel cells with microporous polyethylene/silica membrane as separator.

    PubMed

    Kircheva, Nina; Outin, Jonathan; Perrier, Gérard; Ramousse, Julien; Merlin, Gérard; Lyautey, Emilie

    2015-12-01

    The aim of this work was to study the behavior over time of a separator made of a low-cost and non-selective microporous polyethylene membrane (RhinoHide®) in an air-cathode microbial fuel cell with a reticulated vitreous carbon foam bioanode. Performances of the microporous polyethylene membrane (RhinoHide®) were compared with Nafion®-117 as a cationic exchange membrane. A non-parametric test (Mann-Whitney) done on the different sets of coulombic or energy efficiency data showed no significant difference between the two types of tested membrane (p<0.05). Volumetric power densities were ranging from 30 to 90 W·m(-3) of RVC foam for both membranes. Similar amounts of biomass were observed on both sides of the polyethylene membrane illustrating bacterial permeability of this type of separator. A monospecific denitrifying population on cathodic side of RhinoHide® membrane has been identified. Electrochemical impedance spectroscopy (EIS) was used at OCV conditions to characterize electrochemical behavior of MFCs by equivalent electrical circuit fitted on both Nyquist and Bode plots. Resistances and pseudo-capacitances from EIS analyses do not differ in such a way that the nature of the membrane could be considered as responsible.

  10. Vapor-Particle Separation Using Microporous Metallic Membrane in Crossflow Filtration

    SciTech Connect

    Cheng, Mengdawn

    2013-01-01

    Simultaneous separation of vapor and particles in industrial processes could be a key step toward manufacturing of high-quality goods. The separation is critical for successful measurement of volatile or semi-volatile aerosol particles, which no reliable technique exists. We have developed a technique for separation of vapor and particles simultaneously using a specialty microporous metallic membrane. The separator allows the thermally denuded particles traverse straight through the membrane tube, while the vapor molecules permeate through the membrane, separate from the particles and are removed subsequently. The separation technique virtually eliminates the possibility of contamination by vapor re- condensation. We tested the prototype of the vapor-particle separator (VPS) using aerosols prepared from sodium chloride to represent non-volatile aerosols. Chemical like dioctyl phthalate was chosen to represent volatile particles. The test aerosol particles were generated by an atomizer followed by a tandem differential mobility analyser to produce a stream of monodisperse particles in the size range of 10 to 100 nm. In real world particles, we tested the VPS using diesel engine particles that is a mixture of complex chemical composition. Number concentration of the nonvolatile particles reduced as the temperature increased, but the mode diameter of the aerosol population remained unchanged. Number concentration of the volatile particles was also reduced as the temperature increased, but their mode diameters became smaller as particles shrunk in diameter. Differences in the thermal behaviour of the particles were attributed to its transition energy barrier and evaporation rate. Mass balance analysis suggests the separation of vapor and test particles was reasonably complete. Thus, we conclude the VPS could provide an effective means for quantitative characterization of aerosol volatility and separation of vapors from particles.

  11. Reconstruction of hepatic stellate cell-incorporated liver capillary structures in small hepatocyte tri-culture using microporous membranes.

    PubMed

    Kasuya, Junichi; Sudo, Ryo; Masuda, Genta; Mitaka, Toshihiro; Ikeda, Mariko; Tanishita, Kazuo

    2015-03-01

    In liver sinusoids, hepatic stellate cells (HSCs) locate the outer surface of microvessels to form a functional unit with endothelia and hepatocytes. To reconstruct functional liver tissue in vitro, formation of the HSC-incorporated sinusoidal structure is essential. We previously demonstrated capillary formation of endothelial cells (ECs) in tri-culture, where a polyethylene terephthalate (PET) microporous membrane was intercalated between the ECs and hepatic organoids composed of small hepatocytes (SHs), i.e. hepatic progenitor cells, and HSCs. However, the high thickness and low porosity of the membranes limited heterotypic cell-cell interactions, which are essential to form HSC-EC hybrid structures. Here, we focused on the effective use of the thin and highly porous poly( d, l-lactide-co-glycolide) (PLGA) microporous membranes in SH-HSC-EC tri-culture to reconstruct the HSC-incorporated liver capillary structures in vitro. First, the formation of EC capillary-like structures was induced on Matrigel-coated PLGA microporous membranes. Next, the membranes were stacked on hepatic organoids composed of small SHs and HSCs. When the pore size and porosity of the membranes were optimized, HSCs selectively migrated to the EC capillary-like structures. This process was mediated in part by platelet-derived growth factor (PDGF) signalling. In addition, the HSCs were located along the outer surface of the EC capillary-like structures with their long cytoplasmic processes. In the HSC-incorporated capillary tissues, SHs acquired high levels of differentiated functions, compared to those without ECs. This model will provide a basis for the construction of functional, thick, vascularized liver tissues in vitro.

  12. Graphene-sensitized microporous membrane/solvent microextraction for the preconcentration of cinnamic acid derivatives in Rhizoma Typhonii.

    PubMed

    Xing, Rongrong; Hu, Shuang; Chen, Xuan; Bai, Xiaohong

    2014-09-01

    A novel graphene-sensitized microporous membrane/solvent microextraction method named microporous membrane/graphene/solvent synergistic microextraction, coupled with high-performance liquid chromatography and UV detection, was developed and introduced for the extraction and determination of three cinnamic acid derivatives in Rhizoma Typhonii. Several factors affecting performance were investigated and optimized, including the types of graphene and extraction solvent, concentration of graphene dispersed in octanol, sample phase pH, ionic strength, stirring rate, extraction time, extraction temperature, and sample volume. Under optimized conditions, the enrichment factors of cinnamic acid derivatives ranged from 75 to 269. Good linearities were obtained from 0.01 to 10 μg/mL for all analytes with regression coefficients between 0.9927 and 0.9994. The limits of quantification were <1 ng/mL, and satisfactory recoveries (99-104%) and precision (1.1-10.8%) were also achieved. The synergistic microextraction mechanism based on graphene sensitization was analyzed and described. The experimental results showed that the method was simple, sensitive, practical, and effective for the preconcentration and determination of cinnamic acid derivatives in Rhizoma Typhonii.

  13. Application of micro-porous polycarbonate membranes in dye-sensitized solar cells: Cell performance and long-term stability

    NASA Astrophysics Data System (ADS)

    Lue, Shingjiang Jessie; Lo, Pei Wen; Hung, Ling-Yung; Tung, Yung Liang

    This research investigates the cell performance and long-term stability of dye-sensitized solar cells (DSSCs) containing micro-porous polycarbonate (PC) film as the frame work material to stabilize the electrolyte solution. The track-etched PC film has cylindrical pore geometry, which is beneficial for ion transport in the electrolyte trapped inside the PC film. The photovoltaic efficiency of the DSSC with 0.2-μm PC membrane is 5.75 ± 0.73% under irradiation of 100 mW cm -2, which is slightly lower than that (6.34 ± 0.44%) of cells without PC film. The differences in fill factor and open-circuit voltage between the DSSCs with and without PC film are not statistically significant. The long-term cell performance is carried out at continuous illumination of 100 mW cm -2 (1 sun) and in darkness at 60 °C for up to 1000 h. There is no significant efficiency difference between the cells with and without PC film in light soaking (4.33% vs. 4.52%) for 960 h. In darkness, however, the cells with PC film demonstrate much higher efficiency (at 2.37%) than cells without PC (0.85%) after 1000 h. The improved long-term efficiency data and the higher percentage of working cells confirm the superior lifetime and performance using the micro-porous PC film.

  14. The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes

    PubMed Central

    Akhmetshina, Alsu A.; Davletbaeva, Ilsiya M.; Grebenschikova, Ekaterina S.; Sazanova, Tatyana S.; Petukhov, Anton N.; Atlaskin, Artem A.; Razov, Evgeny N.; Zaripov, Ilnaz I.; Martins, Carla F.; Neves, Luísa A.; Vorotyntsev, Ilya V.

    2015-01-01

    Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence of the modifier used on the polymeric structure was studied. The supported ionic liquid membranes (SILMs) were tested for He, N2, NH3, H2S, and CO2 gas separation and ideal selectivities were calculated. The high values of ideal selectivity for ammonia-based systems with permanent gases were observed on polymer matrixes immobilized with [bmim][PF6] and [emim][Tf2N]. The modification of SILMs by nanosize silica particles leads to an increase of NH3 separation relatively to CO2 or H2S. PMID:26729177

  15. The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes.

    PubMed

    Akhmetshina, Alsu A; Davletbaeva, Ilsiya M; Grebenschikova, Ekaterina S; Sazanova, Tatyana S; Petukhov, Anton N; Atlaskin, Artem A; Razov, Evgeny N; Zaripov, Ilnaz I; Martins, Carla F; Neves, Luísa A; Vorotyntsev, Ilya V

    2015-12-30

    Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf₂N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence of the modifier used on the polymeric structure was studied. The supported ionic liquid membranes (SILMs) were tested for He, N₂, NH₃, H₂S, and CO₂ gas separation and ideal selectivities were calculated. The high values of ideal selectivity for ammonia-based systems with permanent gases were observed on polymer matrixes immobilized with [bmim][PF₆] and [emim][Tf₂N]. The modification of SILMs by nanosize silica particles leads to an increase of NH₃ separation relatively to CO₂ or H₂S.

  16. Microporous layer based on SiC for high temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lobato, Justo; Zamora, Héctor; Cañizares, Pablo; Plaza, Jorge; Rodrigo, Manuel Andrés

    2015-08-01

    This work reports the evaluation of Silicon Carbide (SiC) for its application in microporous layers (MPL) of HT-PEMFC electrodes and compares results with those obtained using conventional MPL based on Vulcan XC72. Influence of the support load on the MPL prepared with SiC was evaluated, and the MPL were characterized by XRD, Hg porosimetry and cyclic voltammetries. In addition, a short lifetest was carried out to evaluate performance in accelerated stress conditions. Results demonstrate that SiC is a promising alternative to carbonaceous materials because of its higher electrochemical and thermal stability and the positive effect on mass transfer associated to its different pore size distribution. Ohmic resistance is the most significant challenge to be overcome in further studies.

  17. On-line automated sample preparation for liquid chromatography using parallel supported liquid membrane extraction and microporous membrane liquid-liquid extraction.

    PubMed

    Sandahl, Margareta; Mathiasson, Lennart; Jönsson, Jan Ake

    2002-10-25

    An automated system was developed for analysis of non-polar and polar ionisable compounds at trace levels in natural water. Sample work-up was performed in a flow system using two parallel membrane extraction units. This system was connected on-line to a reversed-phase HPLC system for final determination. One of the membrane units was used for supported liquid membrane (SLM) extraction, which is suitable for ionisable or permanently charged compounds. The other unit was used for microporous membrane liquid-liquid extraction (MMLLE) suitable for uncharged compounds. The fungicide thiophanate methyl and its polar metabolites carbendazim and 2-aminobenzimidazole were used as model compounds. The whole system was controlled by means of four syringe pumps. While extracting one part of the sample using the SLM technique. the extract from the MMLLE extraction was analysed and vice versa. This gave a total analysis time of 63 min for each sample resulting in a sample throughput of 22 samples per 24 h.

  18. Polysulfide-Blocking Microporous Polymer Membrane Tailored for Hybrid Li-Sulfur Flow Batteries.

    PubMed

    Li, Changyi; Ward, Ashleigh L; Doris, Sean E; Pascal, Tod A; Prendergast, David; Helms, Brett A

    2015-09-01

    Redox flow batteries (RFBs) present unique opportunities for multi-hour electrochemical energy storage (EES) at low cost. Too often, the barrier for implementing them in large-scale EES is the unfettered migration of redox active species across the membrane, which shortens battery life and reduces Coulombic efficiency. To advance RFBs for reliable EES, a new paradigm for controlling membrane transport selectivity is needed. We show here that size- and ion-selective transport can be achieved using membranes fabricated from polymers of intrinsic microporosity (PIMs). As a proof-of-concept demonstration, a first-generation PIM membrane dramatically reduced polysulfide crossover (and shuttling at the anode) in lithium-sulfur batteries, even when sulfur cathodes were prepared as flowable energy-dense fluids. The design of our membrane platform was informed by molecular dynamics simulations of the solvated structures of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) vs lithiated polysulfides (Li2Sx, where x = 8, 6, and 4) in glyme-based electrolytes of different oligomer length. These simulations suggested polymer films with pore dimensions less than 1.2-1.7 nm might incur the desired ion-selectivity. Indeed, the polysulfide blocking ability of the PIM-1 membrane (∼0.8 nm pores) was improved 500-fold over mesoporous Celgard separators (∼17 nm pores). As a result, significantly improved battery performance was demonstrated, even in the absence of LiNO3 anode-protecting additives. PMID:26237233

  19. Polysulfide-Blocking Microporous Polymer Membrane Tailored for Hybrid Li-Sulfur Flow Batteries.

    PubMed

    Li, Changyi; Ward, Ashleigh L; Doris, Sean E; Pascal, Tod A; Prendergast, David; Helms, Brett A

    2015-09-01

    Redox flow batteries (RFBs) present unique opportunities for multi-hour electrochemical energy storage (EES) at low cost. Too often, the barrier for implementing them in large-scale EES is the unfettered migration of redox active species across the membrane, which shortens battery life and reduces Coulombic efficiency. To advance RFBs for reliable EES, a new paradigm for controlling membrane transport selectivity is needed. We show here that size- and ion-selective transport can be achieved using membranes fabricated from polymers of intrinsic microporosity (PIMs). As a proof-of-concept demonstration, a first-generation PIM membrane dramatically reduced polysulfide crossover (and shuttling at the anode) in lithium-sulfur batteries, even when sulfur cathodes were prepared as flowable energy-dense fluids. The design of our membrane platform was informed by molecular dynamics simulations of the solvated structures of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) vs lithiated polysulfides (Li2Sx, where x = 8, 6, and 4) in glyme-based electrolytes of different oligomer length. These simulations suggested polymer films with pore dimensions less than 1.2-1.7 nm might incur the desired ion-selectivity. Indeed, the polysulfide blocking ability of the PIM-1 membrane (∼0.8 nm pores) was improved 500-fold over mesoporous Celgard separators (∼17 nm pores). As a result, significantly improved battery performance was demonstrated, even in the absence of LiNO3 anode-protecting additives.

  20. Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes.

    PubMed

    Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

    2016-01-01

    New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas. PMID:27498607

  1. Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

    NASA Astrophysics Data System (ADS)

    Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

    2016-08-01

    New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, C4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas.

  2. Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes.

    PubMed

    Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

    2016-08-08

    New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas.

  3. Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

    NASA Astrophysics Data System (ADS)

    Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

    2016-08-01

    New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas.

  4. Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

    PubMed Central

    Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

    2016-01-01

    New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas. PMID:27498607

  5. Experimental observations on the effect of added dispersing agent on phenol biodegradation in a microporous membrane bioreactor.

    PubMed

    Juang, Ruey-Shin; Chung, Tsuey-Ping; Wang, Maw-Ling; Lee, Duu-Jong

    2008-03-01

    The effect of added dispersing agent tetrasodium pyrophosphate (TSP) on the degradation of phenol by Pseudomonas putida BCRC 14365 in a microporous membrane bioreactor was experimentally studied at 30 degrees C and pH 7. The hollow fibers were pre-wetted with ethanol to make them more hydrophilic. Phenol solution was passed through the lumen of the module and the cell medium was flowed across the shell. All Experiments were carried out at a fixed initial cell density of 0.023 g/L (0.06 optical density). Phenol could be completely degraded with the help of the biofilm formed on the outer surfaces of the fibers even though its level was high up to 3 g/L. It was also shown that the presence of TSP in cell medium could improve biodegradation. The amount of added TSP was optimized to be 1 g/L under the conditions studied. In this situation, 3 g/L of phenol could be completely removed within 76 h, much shorter than the absence of TSP (within 92 h).

  6. Microporous Poly(L-Lactic Acid) Membranes Fabricated by Polyethylene Glycol Solvent-Cast/Particulate Leaching Technique

    PubMed Central

    Selvam, Shivaram; Chang, Wenji V.; Nakamura, Tamako; Samant, Deedar M.; Thomas, Padmaja B.; Trousdale, Melvin D.; Mircheff, Austin K.; Schechter, Joel E.

    2009-01-01

    With the eventual goal of developing a tissue-engineered tear secretory system, we found that primary lacrimal gland acinar cells grown on solid poly(L-lactic acid) (PLLA) supports expressed the best histiotypic morphology. However, to be able to perform vectorial transport functions, epithelia must be supported by a permeable substratum. In the present study, we describe the use of a solvent-cast/particulate leaching technique to fabricate microporous PLLA membranes (mpPLLAm) from PLLA/polyethylene glycol blends. Scanning electron microscopy revealed pores on both the air-cured (∼4 μm) and glass-cured sides (<2 μm) of the mpPLLAm. Diffusion studies were performed with mpPLLAm fabricated from 57.1% PLLA/42.9% polyethylene glycol blends to confirm the presence of channelized pores. The data reveal that glucose, L-tryptophan, and dextran (a high molecular weight glucose polymer) readily permeate mpPLLAm. Diffusion of the immunoglobulin G through the mpPLLAm decreased with time, suggesting the possible adsorption and occlusion of the pores. Cells cultured on the mpPLLAm (57.1/42.9 wt%) grew to subconfluent monolayers but retained histiotypic morphological and physiological characteristics of lacrimal acinar cells in vivo. Our results suggest that mpPLLAm fabricated using this technique may be useful as a scaffold for a bioartificial lacrimal gland device. PMID:19260769

  7. Multiple inert gas elimination technique by micropore membrane inlet mass spectrometry--a comparison with reference gas chromatography.

    PubMed

    Kretzschmar, Moritz; Schilling, Thomas; Vogt, Andreas; Rothen, Hans Ulrich; Borges, João Batista; Hachenberg, Thomas; Larsson, Anders; Baumgardner, James E; Hedenstierna, Göran

    2013-10-15

    The mismatching of alveolar ventilation and perfusion (VA/Q) is the major determinant of impaired gas exchange. The gold standard for measuring VA/Q distributions is based on measurements of the elimination and retention of infused inert gases. Conventional multiple inert gas elimination technique (MIGET) uses gas chromatography (GC) to measure the inert gas partial pressures, which requires tonometry of blood samples with a gas that can then be injected into the chromatograph. The method is laborious and requires meticulous care. A new technique based on micropore membrane inlet mass spectrometry (MMIMS) facilitates the handling of blood and gas samples and provides nearly real-time analysis. In this study we compared MIGET by GC and MMIMS in 10 piglets: 1) 3 with healthy lungs; 2) 4 with oleic acid injury; and 3) 3 with isolated left lower lobe ventilation. The different protocols ensured a large range of normal and abnormal VA/Q distributions. Eight inert gases (SF6, krypton, ethane, cyclopropane, desflurane, enflurane, diethyl ether, and acetone) were infused; six of these gases were measured with MMIMS, and six were measured with GC. We found close agreement of retention and excretion of the gases and the constructed VA/Q distributions between GC and MMIMS, and predicted PaO2 from both methods compared well with measured PaO2. VA/Q by GC produced more widely dispersed modes than MMIMS, explained in part by differences in the algorithms used to calculate VA/Q distributions. In conclusion, MMIMS enables faster measurement of VA/Q, is less demanding than GC, and produces comparable results.

  8. Facile surface glycosylation of PVDF microporous membrane via direct surface-initiated AGET ATRP and improvement of antifouling property and biocompatibility

    NASA Astrophysics Data System (ADS)

    Yuan, Jing; Meng, Jian-qiang; Kang, Yin-lin; Du, Qi-yun; Zhang, Yu-feng

    2012-01-01

    This paper describes a facile and novel approach for the surface glycosylation of poly(vinylidene difluoride) (PVDF) microporous membrane. A glycopolymer poly(D-gluconamidoethyl methacrylate) (PGAMA) was tethered onto the membrane surface via activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) directly initiated from the PVDF surface. Chemical changes of membrane surface were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It was revealed that PGAMA was successfully grafted onto the membrane surface and its grafting density can be modulated in a wide range up to 2.4 μmol/cm2. The effects of glycosylation on membrane morphology, flux and surface hydrophilicity were investigated. Field emission scanning electron microscopy (FESEM) results indicated shrinkage of the surface pore diameters and the growth of the glycopolymer layer on the membrane surface. The static water contact angle (WCA) of the membrane surface decreased from 110° to 30.4° with the increase of grafting density, indicating that the PGAMA grafts dramatically improved the surface hydrophilicity. The protein adsorption and platelets adhesion experiments indicated that the grafted PGAMA could effectively improve the membrane antifouling property and biocompatibility.

  9. Studies on self-assembly phenomena of hydrophilization of microporous polypropylene membrane by acetone aldol condensation products: New separator for high-power alkaline batteries

    NASA Astrophysics Data System (ADS)

    Ciszewski, Aleksander; Rydzyńska, Bożena

    Commercial hydrophobic polypropylene (PP) membranes were modified by a novel chemical method. This procedure consists of two steps. In the first step, the virgin hydrophobic PP membrane is saturated with acetone; in the second step, the filled membrane is dipped in aqueous KOH solution (d = 1.28 g cm -3), i.e. in the electrolyte typical for the nickel-cadmium cell. This two-step procedure starts the aldol condensation process of acetone and its products accumulated and adsorbed onto walls of micropores make the membrane hydrophilic. The presented method provided the hydrophilic PP membrane, persistent and soaked with KOH solution with electrolytic resistance of 23-29 mΩ cm 2. This result was compared with the data obtained with commercial hydrophilic membranes: Celgard 3501 and Cellophane. The aldol condensation process of acetone was monitored using the HPLC-ES-MS technique, and modified PP membranes were evaluated by FT-IR and SEM measurements. With the above-mentioned membrane as a separator, nickel-cadmium cells showed good high-rate performance.

  10. Composition analysis of a polymer electrolyte membrane fuel cell microporous layer using scanning transmission X-ray microscopy and near edge X-ray absorption fine structure analysis

    NASA Astrophysics Data System (ADS)

    George, Michael G.; Wang, Jian; Banerjee, Rupak; Bazylak, Aimy

    2016-03-01

    The novel application of scanning transmission X-ray microscopy (STXM) to the microporous layer (MPL) of a polymer electrolyte membrane fuel cell is investigated. A spatially resolved chemical component distribution map is obtained for the MPL of a commercially available SGL 25 BC sample. This is achieved with near edge X-ray absorption fine structure spectroscopic analysis. Prior to analysis the sample is embedded in non-reactive epoxy and ultra-microtomed to a thickness of 100 nm. Polytetrafluoroethylene (PTFE), carbon particle agglomerates, and supporting epoxy resin distributions are identified and reconstructed for a scanning area of 6 μm × 6 μm. It is observed that the spatial distribution of PTFE is strongly correlated to the carbon particle agglomerations. Additionally, agglomerate structures of PTFE are identified, possibly indicating the presence of a unique mesostructure in the MPL. STXM analysis is presented as a useful technique for the investigation of chemical species distributions in the MPL.

  11. Microporous membrane liquid-liquid extraction coupled on-line with normal-phase liquid chromatography for the determination of cationic surfactants in river and waste water.

    PubMed

    Norberg, J; Thordarson, E; Mathiasson, L; Jönsson, J A

    2000-02-11

    Membrane-based continuous liquid-liquid extraction combined on-line with normal-phase liquid chromatography is proposed for the determination of cationic surfactants in complex aqueous samples. The technique has the potential for complete automation. Selective enrichment of cationic surfactants from spiked river water and waste-water samples with simultaneous removal of matrix constituents, followed by a quantitative transfer of the extract onto a liquid chromatographic column and separation of the surfactant homologues yielding low detection limits, has been realised. The homologues of alkyldimethylbenzylammonium chloride (Dodigen 226) were chosen as model compounds in the method development. Dodigen homologues were ion-paired with heptanoic acid and extracted into chlorobutane by means of microporous membrane liquid-liquid extraction. It was thereby possible to attain an enrichment of over 250 times for one of the homologues, viz. the concentration in the organic liquid is 250 times higher than in the original sample. Detection limits for the three best-detected homologues of the mixture were in the range 0.7-5 microg/l in spiked river water samples. Ion-pair normal-phase liquid chromatography, again with heptanoic acid as counter-ion, gave the necessary separation of the surfactant homologues.

  12. Evaluation of liquid-liquid microextraction using polypropylene microporous membranes for the determination of organophosphorus flame retardants and plasticizers in water samples.

    PubMed

    García-López, M; Rodríguez, I; Cela, R

    2008-09-12

    In this work, the suitability of the microporous membrane liquid-liquid extraction (MMLLE) technique for the concentration of several organophosphate esters (OPs) in water samples is assessed. Analytes were first extracted into a few microlitres of an organic solvent, immobilized in the pores of a hollow polypropylene membrane, and then determined by gas chromatography with nitrogen-phosphorus detection (GC-NPD). Main parameters controlling the efficiency of the extraction step were identified and their effects on the performance of the technique discussed. Under final working conditions, 2 cm long polypropylene membranes, containing about 7 microL of octanol in the pores, were dipped in a glass vial filled with 115 mL of water with a 30% of sodium chloride. Extractions were carried out for 12h, at room temperature, under magnetic stirring. After that, analytes were recovered from the membrane with 0.2 mL of ethyl acetate. This extract was mixed with the internal standard (50 microL of a tripentyl phosphate solution in the same solvent) and finally reduced to ca. 50 microL. Overall enrichment factors for the optimized method ranged from 35 to 1400 times, and the achieved limits of quantification from 0.008 to 0.12 ng mL(-1), depending on the considered compound. Globally, the method showed an acceptable linearity and precision for all species, except for tris(2-ethylhexyl) phosphate (TEHP). Performance of the MMLLE approach is compared with that reported for other solid- and liquid-phase microextraction techniques and its suitability for the analysis of real water samples discussed. PMID:18724988

  13. Impact of micro-porous layer on liquid water distribution at the catalyst layer interface and cell performance in a polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Tabe, Yutaka; Aoyama, Yusuke; Kadowaki, Kazumasa; Suzuki, Kengo; Chikahisa, Takemi

    2015-08-01

    In polymer electrolyte membrane fuel cells, a gas diffusion layer (GDL) with a micro-porous layer (MPL) gives better anti-flooding performance than GDLs without an MPL. To investigate the function and mechanism of the MPL to suppress water flooding, the liquid water distribution at the cathode catalyst layer (CL) surface are observed by a freezing method; in the method liquid water is immobilized in ice form by rapid freezing, followed by disassembling the cell for observations. The ice covered area is quantified by image processing and cells with and without an MPL are compared. The results show that the MPL suppresses water accumulation at the interface due to smaller pore size and finer contact with the CL, and this results in less water flooding. Investigation of ice formed after -10 °C cold start shutdowns and the temporary performance deterioration at ordinary temperatures also indicates a significant influence of the liquid water accumulating at the interface. The importance of the fine contact between CL and MPL, the relative absence of gaps, is demonstrated by a gas diffusion electrode (GDE) which is directly coated with catalyst ink on the surface of the MPL achieving finer contact of the layers.

  14. Validation of a microbiological method using Acholeplasma laidlawii for assessing performance of microporous membranes for mycoplasma clearance.

    PubMed

    Cronholm, Karen; Bates, Shawn; Nguyen, Nhung; Leahy, Anne; Blanchard, Mark; Lentine, Kerry Roche

    2009-01-01

    While no recognized industry standard currently exists for mycoplasma clearance testing of membrane filters, several methods have been used by membrane manufacturers and contract test laboratories. This validation exercise documents one approach to mycoplasma clearance testing and incorporates validation guidelines recognized in the biopharmaceutical industry today. The benefits of this method are (1) the consistent production of small monodisperse cells, 0.37 x 0.41 microm, at titers in excess of 1 x 10(9) CFU mL(-1) within 20-24 h of incubation; (2) the consistent detection of low levels of Acholeplasma laidlawii with an absence of false negative results; and (3) the ability to distinguish among membrane filters with different bubble points. The results of the validation exercise demonstrate that the equipment, materials, and test methods of the A. laidlawii filter challenge test are suitably understood and in a state of control. This method is appropriate to characterize the performance of membrane filters used in biopharmaceutical applications.

  15. Quantifying the loss of methane through secondary gas mass transport (or 'slip') from a micro-porous membrane contactor applied to biogas upgrading.

    PubMed

    McLeod, Andrew; Jefferson, Bruce; McAdam, Ewan J

    2013-07-01

    Secondary gas transport during the separation of a binary gas with a micro-porous hollow fibre membrane contactor (HMFC) has been studied for biogas upgrading. In this application, the loss or 'slip' of the secondary gas (methane) during separation is a known concern, specifically since methane possesses the intrinsic calorific value. Deionised (DI) water was initially used as the physical solvent. Under these conditions, carbon dioxide (CO2) and methane (CH4) absorption were dependent upon liquid velocity (V(L)). Whilst the highest CO2 flux was recorded at high V(L), selectivity towards CO2 declined due to low residence times and a diminished gas-side partial pressure, and resulted in slip of approximately 5.2% of the inlet methane. Sodium hydroxide was subsequently used as a comparative chemical absorption solvent. Under these conditions, CO2 mass transfer increased by increasing gas velocity (VG) which is attributed to the excess of reactive hydroxide ions present in the solvent, and the fast conversion of dissolved CO2 to carbonate species reinitiating the concentration gradient at the gas-liquid interface. At high gas velocities, CH4 slip was reduced to 0.1% under chemical conditions. Methane slip is therefore dependent upon whether the process is gas phase or liquid phase controlled, since methane mass transport can be adequately described by Henry's law within both physical and chemical solvents. The addition of an electrolyte was found to further retard CH4 absorption via the salting out effect. However, their applicability to physical solvents is limited since electrolytic concentration similarly impinges upon the solvents' capacity for CO2. This study illustrates the significance of secondary gas mass transport, and furthermore demonstrates that gas-phase controlled systems are recommended where greater selectivity is required.

  16. Multiresidue determination of pesticides in industrial and fresh orange juice by hollow fiber microporous membrane liquid-liquid extraction and detection by liquid chromatography-electrospray-tandem mass spectrometry.

    PubMed

    Bedendo, Gizelle Cristina; Jardim, Isabel Cristina Sales Fontes; Carasek, Eduardo

    2012-01-15

    A procedure involving hollow fiber microporous membrane liquid-liquid extraction (HF-MMLLE) and detection by liquid chromatography with tandem mass spectrometry was developed and applied. The extraction is based on liquid-liquid microextraction with a polypropylene porous membrane as a solid support for the solvent. On the membrane walls the solvent forms a renewable liquid membrane which improves the trueness of the method and promotes the sample clean-up. The applicability of this method was evaluated through the simultaneous extraction of 18 pesticides of different classes: polar organophosphates, carbamates, neonicotinoids, amides, pyrimidines, benzimidazoles and triazoles in industrial and fresh orange juice. The parameters affecting the extraction efficiency were optimized by multivariable designs. Under optimized conditions, analytes were concentrated onto 1.5 cm long microporous membranes placed directly into the sample containing 9mL of juice at pH 7.0, 4 g of ammonium sulfate and 400 μL of toluene:ethyl acetate (85:15, v/v). The best extraction conditions were achieved at 25°C with 35 min of extraction time. The analyte desorption was carried out using 50 μL of methanol:acetone (50:50, v/v) for 2 min in an ultrasonic bath. Limits of detection ranging between 0.003-0.33 mgL(-1), 0.003-0.35 mg L(-1) and 0.003-0.15 mgL(-1) were obtained for the carton orange juice, carton light orange juice and fresh orange juice samples, respectively. Good repeatability (lower than 7.6%) was obtained for all three sample types. The method was applied to five different juice samples containing soybean extract, orange pulp, nectar, light juice and fresh orange juice. The results suggest that the proposed method represents a very simple and low-cost alternative microextraction procedure rendering adequate limits of quantification for the determination of these pesticides in juice samples.

  17. Peritrophic membrane origin in adult bees (Hymenoptera): immunolocalization.

    PubMed

    Teixeira, Aparecida das Dores; Marques-Araújo, Solange; Zanuncio, José Cola; Serrão, José Eduado

    2015-01-01

    The midgut is a region of the digestive tract of bees with the lumen lined by a peritrophic membrane that is composed of chitin and proteins (peritrophins). The origin of the peritrophins in the midgut of adult bees is unknown. This study used an anti-peritrophin 55-kDa antibody to immunolocalize the sites of the peritrophic membrane synthesis in nine species of adult bees' representatives of different families and sociability levels. In all studied species the peritrophin-55 is produced by digestive cells in the entire midgut in the rough endoplasmic reticulum following transference to Golgi apparatus and released by secretory vesicles, which fuses with the plasma membrane and microvilli. Thus, in the representatives of different groups of bees, the PM is of type I.

  18. Use of extracorporeal membrane oxygenation in adults.

    PubMed

    Lafç, Gökhan; Budak, Ali Baran; Yener, Ali Ümit; Cicek, Omer Faruk

    2014-01-01

    Since the first successful application of the heart-lung machine in 1953 by John Gibbon [1], great efforts have been made to modify the bypass techniques and devices in order to allow prolonged extracorporeal circulation in the intensive care unit (ICU), commonly referred to as extracorporeal membrane oxygenation (ECMO). ECMO uses classic cardiopulmonary bypass technology to support circulation. It provides continuous, non-pulsatile cardiac output and extracorporeal oxygenation [2]. Veno-venous ECMO (VV ECMO) provides respiratory support, while veno-arterial ECMO (VA ECMO) provides cardio-respiratory support to patients with severe but potentially reversible cardiac or respiratory deterioration refractory to standard therapeutic modalities. ECMO is a temporary form of life support providing a prolonged biventricular circulatory and pulmonary support for patients experiencing both pulmonary and cardiac failure unresponsive to conventional therapy. Despite the advent of newer ventricular assist devices that are more suitable for long term support, ECMO is simple to establish, cost-effective to operate.

  19. Poromechanics of microporous media

    NASA Astrophysics Data System (ADS)

    Brochard, L.; Vandamme, M.; Pellenq, R. J.-M.

    2012-04-01

    Microporous media, i.e., porous media made of pores with a nanometer size, are important for a variety of applications, for instance for sequestration of carbon dioxide in coal, or for storage of hydrogen in metal-organic frameworks. In a pore of nanometer size, fluid molecules are not in their bulk state anymore since they interact with the atoms of the solid: they are said to be in an adsorbed state. For such microporous media, conventional poromechanics breaks down. In this work we derive poroelastic constitutive equations which are valid for a generic porous medium, i.e., even for a porous medium with pores of nanometer size. The complete determination of the poromechanical behavior of a microporous medium requires knowing how the amount of fluid adsorbed depends on both the fluid bulk pressure and the strain of the medium. The derived constitutive equations are validated with the help of molecular simulations on one-dimensional microporous media. Even when a microporous medium behaves linearly in the absence of any fluid (i.e., its bulk modulus does not depend on strain), we show that fluid adsorption can induce non-linear behavior (i.e., its drained bulk modulus can then depend significantly on strain). We also show that adsorption can lead to an apparent Biot coefficient of the microporous medium greater than unity or smaller than zero. The poromechanical response of a microporous medium to adsorption significantly depends on the pore size distribution. Indeed, the commensurability (i.e., the ratio of the size of the pores to that of the fluid molecules) proves to play a major role. For a one-dimensional model of micropores with a variety of pore sizes, molecular simulations show that the amount of adsorbed fluid depends linearly on the strain of the medium. We derive linearized constitutive equations which are valid when such a linear dependence of the adsorbed amount of fluid on the strain is observed. As an application, the case of methane and coal is

  20. Hollow Microporous Organic Capsules

    PubMed Central

    Li, Buyi; Yang, Xinjia; Xia, Lingling; Majeed, Muhammad Irfan; Tan, Bien

    2013-01-01

    Fabrication of hollow microporous organic capsules (HMOCs) could be very useful because of their hollow and porous morphology, which combines the advantages of both microporous organic polymers and non-porous nanocapsules. They can be used as storage materials or reaction chambers while supplying the necessary path for the design of controlled uptake/release systems. Herein, the synthesis of HMOCs with high surface area through facile emulsion polymerization and hypercrosslinking reactions, is described. Due to their tailored porous structure, these capsules possessed high drug loading efficiency, zero-order drug release kinetics and are also demonstrated to be used as nanoscale reactors for the prepareation of nanoparticles (NPs) without any external stabilizer. Moreover, owing to their intrinsic biocompatibility and fluorescence, these capsules exhibit promising prospect for biomedical applications. PMID:23820511

  1. Venovenous extracorporeal membrane oxygenation in adult respiratory failure

    PubMed Central

    Hsin, Chun-Hsien; Wu, Meng-Yu; Huang, Chung-Chi; Kao, Kuo-Chin; Lin, Pyng-Jing

    2016-01-01

    Abstract Despite a potentially effective therapy for adult respiratory failure, a general agreement on venovenous extracorporeal membrane oxygenation (VV-ECMO) has not been reached among institutions due to its invasiveness and high resource usage. To establish consensus on the timing of intervention, large ECMO organizations have published the respiratory extracorporeal membrane oxygenation survival prediction (RESP) score and the ECMOnet score, which allow users to predict hospital mortality for candidates with their pre-ECMO presentations. This study was aimed to test the predictive powers of these published scores in a medium-sized cohort enrolling adults treated with VV-ECMO for acute respiratory failure, and develop an institutional prediction model under the framework of the 3 scores if a superior predictive power could be achieved. This retrospective study included 107 adults who received VV-ECMO for severe acute respiratory failure (a PaO2/FiO2 ratio <70 mm Hg) in a tertiary referral center from 2007 to 2015. Essential demographic and clinical data were collected to calculate the RESP score, the ECMOnet score, and the sequential organ failure assessment (SOFA) score before VV-ECMO. The predictive power of hospital mortality of each score was presented as the area under receiver-operating characteristic curve (AUROC). The multivariate logistic regression was used to develop an institutional prediction model. The surviving to discharge rate was 55% (n = 59). All of the 3 published scores had a real but poor predictive power of hospital mortality in this study. The AUROCs of RESP score, ECMOnet score, and SOFA score were 0.662 (P = 0.004), 0.616 (P = 0.04), and 0.667 (P = 0.003), respectively. An institutional prediction model was established from these score parameters and presented as follows: hospital mortality (Y) = −3.173 + 0.208 × (pre-ECMO SOFA score) + 0.148 × (pre-ECMO mechanical ventilation day) + 1.021

  2. Molecular simulations of supercritical fluid permeation through disordered microporous carbons.

    PubMed

    Boţan, Alexandru; Vermorel, Romain; Ulm, Franz-Josef; Pellenq, Roland J-M

    2013-08-13

    Fluid transport through microporous carbon-based materials is inherent in numerous applications, ranging from gas separation by carbon molecular sieves to natural gas production from coal seams and gas shales. The present study investigates the steady-state permeation of supercritical methane in response to a constant cross-membrane pressure drop. We performed dual control volume grand canonical molecular dynamics (DCV-GCMD) simulations to mimic the conditions of actual permeation experiments. To overcome arbitrary assumptions regarding the investigated porous structures, the membranes were modeled after the CS1000a and CS1000 molecular models, which are representative of real microporous carbon materials. When adsorption-induced molecular trapping (AIMT) mechanisms are negligible, we show that the permeability of the microporous material, although not significantly sensitive to the pressure gradient, monotonically decreases with temperature and reservoir pressures, consistent with diffusion theory. However, when AIMT occurs, the permeability increases with temperature in agreement with experimental data found in the literature. PMID:23886335

  3. Ultra-thin microporous/hybrid materials

    DOEpatents

    Jiang, Ying-Bing; Cecchi, Joseph L.; Brinker, C. Jeffrey

    2012-05-29

    Ultra-thin hybrid and/or microporous materials and methods for their fabrication are provided. In one embodiment, the exemplary hybrid membranes can be formed including successive surface activation and reaction steps on a porous support that is patterned or non-patterned. The surface activation can be performed using remote plasma exposure to locally activate the exterior surfaces of porous support. Organic/inorganic hybrid precursors such as organometallic silane precursors can be condensed on the locally activated exterior surfaces, whereby ALD reactions can then take place between the condensed hybrid precursors and a reactant. Various embodiments can also include an intermittent replacement of ALD precursors during the membrane formation so as to enhance the hybrid molecular network of the membranes.

  4. Particle-filled microporous materials

    DOEpatents

    McAllister, J.W.; Kinzer, K.E.; Mrozinski, J.S.; Johnson, E.J.; Dyrud, J.F.

    1990-09-18

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated. 3 figs.

  5. Particle-filled microporous materials

    DOEpatents

    McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.; Dyrud, James F.

    1990-01-01

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

  6. Particle-filled microporous materials

    DOEpatents

    McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.

    1992-07-14

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

  7. A highly crystalline layered silicate with three-dimensionally microporous layers

    NASA Astrophysics Data System (ADS)

    Jeong, Hae-Kwon; Nair, Sankar; Vogt, Thomas; Dickinson, L. Charles; Tsapatsis, Michael

    2003-01-01

    Layered silicates with three-dimensional microporosity within the layers have the potential to enable new applications in catalysis, adsorption and ion-exchange. Until now no such materials have been reported. However, here we present the synthesis and structure of AMH-3, a silicate with three-dimensionally microporous layers, obtained in high purity and crystallinity. AMH-3 is composed of silicate layers containing eight-membered rings in all three principal crystal directions, and spaced by strontium cations, sodium cations and water molecules. Because of its three-dimensional pore structure, acid and thermal stability, this layered material could find applications in polymer-silicate composites for membrane applications, for synthesis of combined microporous-mesoporous materials, and for the formation of new zeolites and microporous films. Its existence also opens new possibilities for the synthesis of other layered silicates with multidimensional microporous framework layers.

  8. Alternative Sources of Adult Stem Cells: Human Amniotic Membrane

    NASA Astrophysics Data System (ADS)

    Wolbank, Susanne; van Griensven, Martijn; Grillari-Voglauer, Regina; Peterbauer-Scherb, Anja

    Human amniotic membrane is a highly promising cell source for tissue engineering. The cells thereof, human amniotic epithelial cells (hAEC) and human amniotic mesenchymal stromal cells (hAMSC), may be immunoprivileged, they represent an early developmental status, and their application is ethically uncontroversial. Cell banking strategies may use freshly isolated cells or involve in vitro expansion to increase cell numbers. Therefore, we have thoroughly characterized the effect of in vitro cultivation on both phenotype and differentiation potential of hAEC. Moreover, we present different strategies to improve expansion including replacement of animal-derived supplements by human platelet products or the introduction of the catalytic subunit of human telomerase to extend the in vitro lifespan of amniotic cells. Characterization of the resulting cultures includes phenotype, growth characteristics, and differentiation potential, as well as immunogenic and immunomodulatory properties.

  9. Filtration performance of microporous ceramic supports.

    PubMed

    Belouatek, Aissa; Ouagued, Abdellah; Belhakem, Mustapha; Addou, Ahmed

    2008-04-24

    The use of inorganic membranes in pollution treatment is actually limited by the cost of such membranes. Advantages of inorganic membranes are their chemical, thermal and pH properties. The purpose of this work was the development of microporous ceramic materials based on clay for liquid waste processing. The supports or ceramic filters having various compositions were prepared and thermally treated at 1100 degrees C. The results show that, at the temperature studied, porosity varied according to the support composition from 12% for the double-layered (ceramic) support to 47% for the activated carbon- filled support with a mean pore diameter between 0.8 and 1.3 microm, respectively. Volumes of 5 l of distilled water were filtered tangentially for 3 h under an applied pressure of 3.5 and 5.5 bar. The retention of tubular supports prepared was tested with molecules of varying size (Evans blue, NaCl and Sacharose). The study of the liquid filtration and flow through these supports showed that the retention rate depends on support composition and pore diameter, and solute molecular weight. The S1 support (mixture of barbotine and 1% (w/w) activated carbon) gave a flux for distilled water of 68 L/m2 h while the double-layered support resulted in a flux of 8 L/m2 h for the same solution at the pressure of 3.5 bar. At a pressure of 5.5 bar an increase in the distilled water flux through the various supports was observed. It was significant for the S1 support (230 L/m h).

  10. Silicon Micropore based Electromechanical Transducer to Differentiate Tumor Cells

    NASA Astrophysics Data System (ADS)

    Ali, Waqas; Raza, Muhammad U.; Khanzada, Raja R.; Kim, Young-Tae; Iqbal, Samir M.

    2015-03-01

    Solid-state micropores have been used before to differentiate cancer cells from normal cells using size-based filtering. Tumor cells differ from normal ones not only in size but also in physical properties like elasticity, shape, motility etc. Tumor cells show different physical attributes depending on the stage and type of cancer. We report a micropore based electromechanical transducer that differentiated cancer cells based on their mechanophysical properties. The device was interfaced with a high-speed patch-clamp measurement system that biased the ionic solution across the silicon-based membrane. The bias resulted in the flow of ionic current. Electrical pulses were generated when cells passed through. Different cells depicted characteristic pulses. Translocation profiles of cells that were either small or were more elastic and flexible caused electrical pulses shorter in widths and amplitudes whereas cells with larger size or lesser elasticity/flexibility showed deeper and wider pulses. Three non-small cell lung cancer (NSCLC) cell lines NCI-H1155, A549 and NCI-H460 were successfully differentiated. NCI-H1155, due to their comparatively smaller size, were found quickest in translocating through. The solid-sate micropore based electromechanical transducer could process the whole blood sample of cancer patient without any pre-processing requirements and is ideal for point-of-care applications. Support Acknowledged from NSF through ECCS-1201878.

  11. [The delivery mechanism of micro-porous osmotic pump tablets].

    PubMed

    Zhao, Xue-ling; Li, Qiang; Gong, Xian-feng; Li, San-ming

    2007-02-01

    To investigate the delivery mechanism of micro-porous osmotic pump tablets ( MPOP), taking tramadol hydrochloride ( TR) as the model drug, tramadol hydrochloride micro-porous osmotic pump tablets (TR MPOP) were prepared with compressible starch as diluent, cellulose acetate as coating material, polyethylene glycol 400 as pore-forming agents. The equilibrium solubility and osmolality of TR were determined. The effects of fillers in tablet cores, coating levels, and osmotic pressures of release media on expansion behavior of preparations were described. The influences of the category, osmolality, and pH value of release media, release methods, and release conditions on release curves of tablets were evaluated. Based on several models, the delivery pattern of TR MPOP was fitted. The equilibrium solubility in water and osmolality of TR were (775.8 +/- 17.7) g x L(-1) and 4.036 Osmol x kg(-1), respectively. During the drug-release period, it was observed that the tablets expanded markedly in response to the expansion characteristics of compressible starch and the osmotic pressure difference across the membrane. When osmotic pressure of release media increased, the significant change of the equilibrium solubility of TR was not found, but the release rates of TR MPOP decreased significantly. The delivery rate was not influenced by the pH of release mediums, dissolution methods and paddle stirring rates. The drug release profile conformed to the model of zero order in 8 h. The pore-forming agents were dissolved in release medium, which caused micro-pores. The expansion of tablets made the size of micropores bigger, and then the drug-releasing pores were obtained. It was proved that the drivers of drug delivering from TR MPOP were mainly the difference of osmotic pressure, and secondly the difference of solubility. TR MPOP were the controlled-release preparation.

  12. Membrane domains of intestinal epithelial cells: distribution of Na+,K+- ATPase and the membrane skeleton in adult rat intestine during fetal development and after epithelial isolation

    PubMed Central

    1989-01-01

    The organization of the basolateral membrane domain of highly polarized intestinal absorptive cells was studied in adult rat intestinal mucosa, during development of polarity in fetal intestine, and in isolated epithelial sheets. Semi-thin frozen sections of these tissues were stained with a monoclonal antibody (mAb 4C4) directed against Na+,K+- ATPase, and with other reagents to visualize distributions of the membrane skeleton (fodrin), an epithelial cell adhesion molecule (uvomorulin), an apical membrane enzyme (aminopeptidase), and filamentous actin. In intact adult epithelium, Na+,K+-ATPase, membrane- associated fodrin, and uvomorulin were concentrated in the lateral, but not basal, subdomain. In the stratified epithelium of fetal intestine, both fodrin and uvomorulin were localized in areas of cell-cell contact at 16 and 17 d gestation, a stage when Na+,K+-ATPase was not yet expressed. These molecules were excluded from apical domains and from cell surfaces in contact with basal lamina. When Na+,K+-ATPase appeared at 18-19 d, it was codistributed with fodrin. Detachment of epithelial sheets from adult intestinal mucosa did not disrupt intercellular junctions or lateral cell contacts, but cytoplasmic blebs appeared at basal cell surfaces, and a diffuse pool of fodrin and actin accumulated in them. At the same time, Na+,K+-ATPase moved into the basal membrane subdomain, and extensive endocytosis of basolateral membrane, including Na+,K+-ATPase, occurred. Endocytosis of uvomorulin was not detected and no fodrin was associated with endocytic vesicles. Uvomorulin, along with some membrane-associated fodrin and some Na+,K+-ATPase, remained in the lateral membrane as long as intercellular contacts were maintained. Thus, in this polarized epithelium, interaction of lateral cell-cell adhesion molecules as well as basal cell-substrate interactions are required for maintaining the stability of the lateral membrane skeleton and the position of resident membrane proteins

  13. Tetrakis-amido high flux membranes

    DOEpatents

    McCray, Scott B.

    1989-01-01

    Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

  14. Tetrakis-amido high flux membranes

    DOEpatents

    McCray, S.B.

    1989-10-24

    Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

  15. Composite membranes for fluid separations

    DOEpatents

    Blume, Ingo; Peinemann, Klaus-Viktor; Pinnau, Ingo; Wijmans, Johannes G.

    1992-01-01

    A method for designing and making composite membranes having a microporous support membrane coated with a permselective layer. The method involves calculating the minimum thickness of the permselective layer such that the selectivity of the composite membrane is close to the intrinsic selectivity of the perselective layer. The invention also provides high performance membranes with optimized properties.

  16. Composite membranes for fluid separations

    DOEpatents

    Blume, Ingo; Peinemann, Klaus-Viktor; Pinnau, Ingo; Wijmans, Johannes G.

    1990-01-01

    A method for designing and making composite membranes having a microporous support membrane coated with a permselective layer. The method involves calculating the minimum thickness of the permselective layer such that the selectivity of the composite membrane is close to the intrinsic selectivity of the permselective layer. The invention also provides high performance membranes with optimized properties.

  17. Composite membranes for fluid separations

    DOEpatents

    Blume, Ingo; Peinemann, Klaus-Viktor; Pinnau, Ingo; Wijmans, Johannes G.

    1991-01-01

    A method for designing and making composite membranes having a microporous support membrane coated with a permselective layer. The method involves calculating the minimum thickness of the permselective layer such that the selectivity of the composite membrane is close to the intrinsic selectivity of the permselective layer. The invention also provides high performance membranes with optimized properties.

  18. Search for selective ion diffusion through membranes

    NASA Technical Reports Server (NTRS)

    May, C. E.; Philipp, W. H.

    1983-01-01

    The diffusion rates of several ions through some membranes developed as battery separators were measured. The ions investigated were Li(+), Rb(+), Cl(-), and So4. The members were crosslinked polyvinyl alcohol, crosslinked polyacrylic acid, a copolymer of the two, crosslinked calcium polyacrylate, cellulose, and several microporous polyphenylene oxide based films. No true specificity for diffusion of any of these ions was found for any of the membranes. But the calcium polyacrylate membrane was found to exhibit ion exchange with the diffusing ions giving rise to the leaching of the calcium ion and low reproducibility. These findings contrast earlier work where the calcium polyacrylate membrane did show specificity to the diffusion of the copper ion. In general, Fick's law appeared to be obeyed. Except for the microporous membranes, the coefficients for ion diffusion through the membranes were comparable with their values in water. For the microporous membranes, the values found for the coefficients were much less, due to the tortuosity of the micropores.

  19. Pressure induced swelling in microporous materials

    DOEpatents

    Vogt, Thomas; Hriljac, Joseph A.; Lee, Yongjae

    2006-07-11

    A method for capturing specified materials which includes contacting a microporous material with a hydrostatic fluid having at least one specified material carried therein, under pressure which structurally distorts the lattice sufficiently to permit entry of the at least one specified material. The microporous material is capable of undergoing a temporary structural distortion which alters resting lattice dimensions under increased ambient pressure and at least partially returning to rest lattice dimensions when returned to ambient pressure. The pressure of the fluid is then reduced to permit return to at least partial resting lattice dimension while the at least one specified material is therein. By this method, at least one specified material is captured in the microporous material to form a modified microporous material.

  20. Does aberrant membrane transport contribute to poor outcome in adult acute myeloid leukemia?

    PubMed Central

    Chigaev, Alexandre

    2015-01-01

    Acute myeloid leukemia in adults is a highly heterogeneous disease. Gene expression profiling performed using unsupervised algorithms can be used to distinguish specific groups of patients within a large patient cohort. The identified gene expression signatures can offer insights into underlying physiological mechanisms of disease pathogenesis. Here, the analysis of several related gene expression clusters associated with poor outcome, worst overall survival and highest rates of resistant disease and obtained from the patients at the time of diagnosis or from previously untreated individuals is presented. Surprisingly, these gene clusters appear to be enriched for genes corresponding to proteins involved in transport across membranes (transporters, carriers and channels). Several ideas describing the possible relationship of membrane transport activity and leukemic cell biology, including the “Warburg effect,” the specific role of chloride ion transport, direct “import” of metabolic energy through uptake of creatine phosphate, and modification of the bone marrow niche microenvironment are discussed. PMID:26191006

  1. Unprovoked deep venous thrombosis in a young adult associated with membranous obstruction of inferior vena cava.

    PubMed

    Epperla, Narendranath; Usoltseva, Natalia

    2014-01-01

    Unprovoked deep venous thrombosis (DVT) in young adults is an unusual phenomenon, but it is associated with significant morbidity. Developmental anomalies of the inferior vena cava (IVC) should be considered as a possible aetiological factor, and appropriate investigations should be performed to determine the conclusive diagnosis and necessary treatment plan. We report a case of spontaneous thrombosis of the IVC and bilateral iliac venous system in a young man, associated with membranous obstruction of the IVC. He was diagnosed using several different investigational techniques, and successfully treated with mechanical thrombectomy, thrombolysis therapy and anticoagulation.

  2. Extracorporeal membrane oxygenation and CO2 removal in an adult after near drowning.

    PubMed

    Peralta, Ruben; Ryan, Daniel P; Iribrane, Alexander; Fitzsimons, Michael G

    2005-03-01

    Near drowning is a common event among otherwise healthy young people. The development of ARDS in the setting may significantly increase mortality. The traditional means of ventilation may lead to barotrauma. Extracorporeal membrane oxygenation (ECMO) is an effective means to improve oxygenation and remove carbon dioxide, while allowing the lungs to recover from the acute insult. It may be especially successful in those victims with single organ injury. We report the use of ECMO in a young adult with ARDS and pneumonia after near drowning.

  3. Interface physics in microporous media : LDRD final report.

    SciTech Connect

    Yaklin, Melissa A.; Knutson, Chad E.; Noble, David R.; Aragon, Alicia R.; Chen, Ken Shuang; Giordano, Nicholas J.; Brooks, Carlton, F.; Pyrak-Nolte, Laura J.; Liu, Yihong

    2008-09-01

    This document contains a summary of the work performed under the LDRD project entitled 'Interface Physics in Microporous Media'. The presence of fluid-fluid interfaces, which can carry non-zero stresses, distinguishes multiphase flows from more readily understood single-phase flows. In this work the physics active at these interfaces has been examined via a combined experimental and computational approach. One of the major difficulties of examining true microporous systems of the type found in filters, membranes, geologic media, etc. is the geometric uncertainty. To help facilitate the examination of transport at the pore-scale without this complication, a significant effort has been made in the area of fabrication of both two-dimensional and three-dimensional micromodels. Using these micromodels, multiphase flow experiments have been performed for liquid-liquid and liquid-gas systems. Laser scanning confocal microscopy has been utilized to provide high resolution, three-dimensional reconstructions as well as time resolved, two-dimensional reconstructions. Computational work has focused on extending lattice Boltzmann (LB) and finite element methods for probing the interface physics at the pore scale. A new LB technique has been developed that provides over 100x speed up for steady flows in complex geometries. A new LB model has been developed that allows for arbitrary density ratios, which has been a significant obstacle in applying LB to air-water flows. A new reduced order model has been developed and implemented in finite element code for examining non-equilibrium wetting in microchannel systems. These advances will enhance Sandia's ability to quantitatively probe the rich interfacial physics present in microporous systems.

  4. Venovenous extracorporeal membrane oxygenation in adult respiratory failure: Scores for mortality prediction.

    PubMed

    Hsin, Chun-Hsien; Wu, Meng-Yu; Huang, Chung-Chi; Kao, Kuo-Chin; Lin, Pyng-Jing

    2016-06-01

    Despite a potentially effective therapy for adult respiratory failure, a general agreement on venovenous extracorporeal membrane oxygenation (VV-ECMO) has not been reached among institutions due to its invasiveness and high resource usage. To establish consensus on the timing of intervention, large ECMO organizations have published the respiratory extracorporeal membrane oxygenation survival prediction (RESP) score and the ECMOnet score, which allow users to predict hospital mortality for candidates with their pre-ECMO presentations. This study was aimed to test the predictive powers of these published scores in a medium-sized cohort enrolling adults treated with VV-ECMO for acute respiratory failure, and develop an institutional prediction model under the framework of the 3 scores if a superior predictive power could be achieved. This retrospective study included 107 adults who received VV-ECMO for severe acute respiratory failure (a PaO2/FiO2 ratio <70 mm Hg) in a tertiary referral center from 2007 to 2015. Essential demographic and clinical data were collected to calculate the RESP score, the ECMOnet score, and the sequential organ failure assessment (SOFA) score before VV-ECMO. The predictive power of hospital mortality of each score was presented as the area under receiver-operating characteristic curve (AUROC). The multivariate logistic regression was used to develop an institutional prediction model. The surviving to discharge rate was 55% (n = 59). All of the 3 published scores had a real but poor predictive power of hospital mortality in this study. The AUROCs of RESP score, ECMOnet score, and SOFA score were 0.662 (P = 0.004), 0.616 (P = 0.04), and 0.667 (P = 0.003), respectively. An institutional prediction model was established from these score parameters and presented as follows: hospital mortality (Y) = -3.173 + 0.208 × (pre-ECMO SOFA score) + 0.148 × (pre-ECMO mechanical ventilation day) + 1.021

  5. High-Throughput Cloning of Temperature-Sensitive Caenorhabditis elegans Mutants with Adult Syncytial Germline Membrane Architecture Defects

    PubMed Central

    Lowry, Josh; Yochem, John; Chuang, Chien-Hui; Sugioka, Kenji; Connolly, Amy A.; Bowerman, Bruce

    2015-01-01

    The adult Caenorhabditis elegans hermaphrodite gonad consists of two mirror-symmetric U-shaped arms, with germline nuclei located peripherally in the distal regions of each arm. The nuclei are housed within membrane cubicles that are open to the center, forming a syncytium with a shared cytoplasmic core called the rachis. As the distal germline nuclei progress through meiotic prophase, they move proximally and eventually cellularize as their compartments grow in size. The development and maintenance of this complex and dynamic germline membrane architecture are relatively unexplored, and we have used a forward genetic screen to identify 20 temperature-sensitive mutations in 19 essential genes that cause defects in the germline membrane architecture. Using a combined genome-wide SNP mapping and whole genome sequencing strategy, we have identified the causal mutations in 10 of these mutants. Four of the genes we have identified are conserved, with orthologs known to be involved in membrane biology, and are required for proper development or maintenance of the adult germline membrane architecture. This work provides a starting point for further investigation of the mechanisms that control the dynamics of syncytial membrane architecture during adult oogenesis. PMID:26311651

  6. Veno-arterial extracorporeal membrane oxygenation for cardiogenic shock due to myocarditis in adult patients.

    PubMed

    Pozzi, Matteo; Banfi, Carlo; Grinberg, Daniel; Koffel, Catherine; Bendjelid, Karim; Robin, Jacques; Giraud, Raphaël; Obadia, Jean François

    2016-07-01

    Myocarditis is an inflammatory disease of the heart muscle with established histological, immunological and immunohistochemical diagnostic criteria. Different triggers could be advocated as possible etiologies of myocarditis such as viral and non-viral infections, medications, systemic autoimmune diseases and toxic reactions. The spectrum of clinical presentations of myocarditis is broad and varies from subclinical asymptomatic courses to refractory cardiogenic shock. The prognosis of patients with myocarditis depends mainly on the severity of clinical presentation. In particular, myocarditis patients developing cardiogenic shock refractory to optimal maximal medical treatment may benefit from the use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) as a temporary mechanical circulatory support (MCS). The aim of the present report is to offer a review of the most important articles of the literature showing the results of VA-ECMO in the specific setting of cardiogenic shock due to myocarditis in adult patients. PMID:27499982

  7. A Population Pharmacokinetic Model for Vancomycin in Adult Patients Receiving Extracorporeal Membrane Oxygenation Therapy.

    PubMed

    Moore, J N; Healy, J R; Thoma, B N; Peahota, M M; Ahamadi, M; Schmidt, L; Cavarocchi, N C; Kraft, W K

    2016-09-01

    The literature on the pharmacokinetics of vancomycin in patients undergoing extracorporeal membrane oxygenation (ECMO) therapy is sparse. A population pharmacokinetic (PK) model for vancomycin in ECMO patients was developed using a nonlinear mixed effects modeling on the concentration-time profiles of 14 ECMO patients who received intravenous vancomycin. Model selection was based on log-likelihood criterion, goodness of fit plots, and scientific plausibility. Identification of covariates was done using a full covariate model approach. The pharmacokinetics of vancomycin was adequately described with a two-compartment model. Parameters included clearance of 2.83 L/hr, limited central volume of distribution 24.2 L, and low residual variability 0.67%. Findings from the analysis suggest that standard dosing recommendations for vancomycin in non-ECMO patients are adequate to achieve therapeutic trough concentrations in ECMO patients. This further shows that ECMO minimally affects the PK of vancomycin in adults including in higher-weight patients. PMID:27639260

  8. A Population Pharmacokinetic Model for Vancomycin in Adult Patients Receiving Extracorporeal Membrane Oxygenation Therapy

    PubMed Central

    Healy, JR; Thoma, BN; Peahota, MM; Ahamadi, M; Schmidt, L; Cavarocchi, NC; Kraft, WK

    2016-01-01

    The literature on the pharmacokinetics of vancomycin in patients undergoing extracorporeal membrane oxygenation (ECMO) therapy is sparse. A population pharmacokinetic (PK) model for vancomycin in ECMO patients was developed using a nonlinear mixed effects modeling on the concentration–time profiles of 14 ECMO patients who received intravenous vancomycin. Model selection was based on log‐likelihood criterion, goodness of fit plots, and scientific plausibility. Identification of covariates was done using a full covariate model approach. The pharmacokinetics of vancomycin was adequately described with a two‐compartment model. Parameters included clearance of 2.83 L/hr, limited central volume of distribution 24.2 L, and low residual variability 0.67%. Findings from the analysis suggest that standard dosing recommendations for vancomycin in non‐ECMO patients are adequate to achieve therapeutic trough concentrations in ECMO patients. This further shows that ECMO minimally affects the PK of vancomycin in adults including in higher‐weight patients. PMID:27639260

  9. Influence of pH and temperature on hemolysis by adult Schistosoma mansoni membranes.

    PubMed

    Kasschau, M R; Byam-Smith, M P; Gentry, D S; Watson, F N

    1995-03-01

    Membrane fractions from homogenized adult Schistosoma mansoni are known to lyse host red blood cells (RBC's), which serve as an important nutrient source for the parasite. In order to learn more about the hemolytic process, we investigated the effects of pH and temperature on the steps involved in the hemolytic process. For maximum schistosome induced hemolysis to occur the worm lytic agent must be in contact with RBCs in a low pH (pH 5.1), high temperature (37 degrees C) environment for a short time (30 min), after which hemolysis occurs at both pH 7.5 and 5.1. At pH 7.5 the hemolytic process is relatively temperature independent and highly concentration dependent. Dose-response experiments suggest that a multi-hit process of hemolysis is probably involved. Temperature and dextran experiments suggest that a pore is formed in the RBC membrane at pH 7.5. At pH 5.1 hemolysis is temperature dependent and not very concentration dependent. Dose-response data suggest that a single-hit process of hemolysis is utilized at low pH. The hemolytic process at pH 7.5, the pH of the host blood, and pH 5.1, the approximate pH of the worm gut, appears to be very different. PMID:7722474

  10. 21 CFR 177.2250 - Filters, microporous polymeric.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Filters, microporous polymeric. 177.2250 Section... as Components of Articles Intended for Repeated Use § 177.2250 Filters, microporous polymeric. Microporous polymeric filters identified in paragraph (a) of this section may be safely used, subject to...

  11. 21 CFR 177.2250 - Filters, microporous polymeric.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Filters, microporous polymeric. 177.2250 Section... as Components of Articles Intended for Repeated Use § 177.2250 Filters, microporous polymeric. Microporous polymeric filters identified in paragraph (a) of this section may be safely used, subject to...

  12. 21 CFR 177.2250 - Filters, microporous polymeric.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Filters, microporous polymeric. 177.2250 Section... as Components of Articles Intended for Repeated Use § 177.2250 Filters, microporous polymeric. Microporous polymeric filters identified in paragraph (a) of this section may be safely used, subject to...

  13. 21 CFR 177.2250 - Filters, microporous polymeric.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Filters, microporous polymeric. 177.2250 Section... as Components of Articles Intended for Repeated Use § 177.2250 Filters, microporous polymeric. Microporous polymeric filters identified in paragraph (a) of this section may be safely used, subject to...

  14. Supported liquid membrane system

    SciTech Connect

    Takigawa, D.Y.; Bush, H. Jr.

    1990-12-31

    A cell apparatus for a supported liquid membrane including opposing faceplates, each having a spirally configured groove, an inlet groove at a first end of the spirally configured groove, and an outlet groove at the other end of the spirally configured groove, within the opposing faces of the faceplates, a microporous membrane situated between the grooved faces of the faceplates, said microporous membrane containing an extractant mixture selective for a predetermined chemical species within the pores of said membrane, means for aligning the grooves of the faceplates in an directly opposing configuration with the porous membrane being situated therebetween, such that the aligned grooves form a pair of directly opposing channels, separate feed solution and stripping solution compartments connected to respective channels between the faceplates and the membrane, separate pumping means for passing feed solution and stripping solution through the channels is provided.

  15. Electrochemically Produced Graphene for Microporous Layers in Fuel Cells.

    PubMed

    Najafabadi, Amin Taheri; Leeuwner, Magrieta J; Wilkinson, David P; Gyenge, Előd L

    2016-07-01

    The microporous layer (MPL) is a key cathodic component in proton exchange membrane fuel cells owing to its beneficial influence on two-phase mass transfer. However, its performance is highly dependent on material properties such as morphology, porous structure, and electrical resistance. To improve water management and performance, electrochemically exfoliated graphene (EGN) microsheets are considered as an alternative to the conventional carbon black (CB) MPLs. The EGN-based MPLs decrease the kinetic overpotential and the Ohmic potential loss, whereas the addition of CB to form a composite EGN+CB MPL improves the mass-transport limiting current density drastically. This is reflected by increases of approximately 30 and 70 % in peak power densities at 100 % relative humidity (RH) compared with those for CB- and EGN-only MPLs, respectively. The composite EGN+CB MPL also retains the superior performance at a cathode RH of 20 %, whereas the CB MPL shows significant performance loss. PMID:27254459

  16. Binding kinetics of Clostridium difficile toxins A and B to intestinal brush border membranes from infant and adult hamsters

    SciTech Connect

    Rolfe, R.D. )

    1991-04-01

    This study was undertaken to determine if the relative resistance of neonates and infants to Clostridium difficile-associated intestinal disease can be related to age-dependent differences in intestinal receptors for C. difficile toxins A and B. Brush border membranes (BBMs) from the small intestines of adult and infant hamsters were examined for their ability to bind radiolabeled toxins A and B. (125I)toxin A bound to both infant and adult hamster BBMs at physiological temperature, whereas (125I)toxin B did not bind to the BBMs under any of the conditions examined. The number of (125I)toxin A molecules bound at saturation was approximately 4 x 10(10) per micrograms of membrane protein for adult BBMs and 1 x 10(11) per micrograms of membrane protein for infant BBMs. Scatchard plot analysis suggested the presence of a single class of toxin A binding sites on both infant and adult hamster BBMs. Maximal binding capacity and Kd values were 0.63 pmol/mg of protein and 66.7 nM, respectively, for the infant BBMs, and 0.24 pmol/mg of protein and 27 nM, respectively, for the adult BBMs. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses of extracted BBM proteins revealed differences in the proteins of infant and adult BBMs. However, there were not any detectable differences in the protein bands which bound (125I)toxin A between infant and adult hamsters. The results from these investigations indicate that differences in the binding kinetics of toxins A and/or B to infant and adult hamster BBMs do not account for the observed differences in their susceptibility to C. difficile-associated intestinal disease.

  17. 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.

  18. Separation of metals by supported liquid membranes

    SciTech Connect

    Takigawa, D.Y.

    1990-12-31

    A supported liquid membrane system for the separation of a preselected chemical species within a feedstream, preferably an aqueous feedstream, includes a feed compartment containing a feed solution having at least one preselected chemical species therein, a stripping compartment containing a stripping solution therein, and a microporous polybenzimidazole membrane situated between the compartments, the microporous polybenzimidazole membrane containing an extractant mixture selective for the preselected chemical species within the membrane pores is disclosed along with a method of separating preselected chemical species from a feedstream with such a system, and a supported liquid membrane for use in such a system.

  19. Role of extracorporeal membrane oxygenation in adult respiratory failure: an overview.

    PubMed

    Anand, Suneesh; Jayakumar, Divya; Aronow, Wilbert S; Chandy, Dipak

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) provides complete or partial support of the heart and lungs. Ever since its inception in the 1960s, it has been used across all age groups in the management of refractory respiratory failure and cardiogenic shock. While it has gained widespread acceptance in the neonatal and pediatric physician community, ECMO remains a controversial therapy for Acute Respiratory Distress Syndrome (ARDS) in adults. Its popularity was revived during the swine flu (H1N1) pandemic and advancements in technology have contributed to its increasing usage. ARDS continues to be a potentially devastating condition with significant mortality rates. Despite gaining more insights into this entity over the years, mechanical ventilation remains the only life-saving, yet potentially harmful intervention available for ARDS. ECMO shows promise in this regard by offering less dependence on mechanical ventilation, thereby potentially reducing ventilator-induced injury. However, the lack of rigorous clinical data has prevented ECMO from becoming the standard of care in the management of ARDS. Therefore, the results of two large ongoing randomized trials, which will hopefully throw more light on the role of ECMO in the management of this disease entity, are keenly awaited. In this article we will provide a basic overview of the development of ECMO, the types of ECMO, the pathogenesis of ARDS, different ventilation strategies for ARDS, the role of ECMO in ARDS and the role of ECMO as a bridge to lung transplantation. PMID:26848884

  20. Electron transfer reactions in microporous solids

    SciTech Connect

    Mallouk, T.E.

    1993-01-01

    Basic thrust the research program involves use of microporous solids (zeolites, clays, layered and tunnel structure oxide semiconductors) as organizing media for artificial photosynthetic systems. Purpose of the microporous solid is twofold. First, it induces spatial organization of photoactive and electroactive components (sensitizers, semiconductor particles, electron relays, and catalysts) at the solid-solution interface, enhancing the quantum efficiency of charge separation and separating physically the ultimate electron donor and acceptor in the electron transport chain. Second, since the microcrystalline solid admits only molecules of a certain charge and size, it is possible to achieve permanent charge separation by sieving chemical photoproducts (e.g., H[sub 2] and I[sub 3][sup [minus

  1. Microporous glassy fillers for dental composites.

    PubMed

    Mabie, C P; Menis, D L

    1978-07-01

    A microporous filler giving greatly improved finish ability, systemic nontoxic X-ray opacification, low thermal expansion (27.2 x 10(-6)/degrees C), and satisfactory translucencies has been developed for dental composite resin restorations. These fillers are prepared from frits obtained by the low-temperature calcination of gelled inorganic sols followed by a pulsed high-temperature treatment. Composites prepared from these fillers are within the range of commercial products with regard to strength and setting contraction.

  2. Microporous polyimide films for reduced dielectric applications

    SciTech Connect

    Saunders, R.S.; Aubert, J.H.; McNamara, W.F.

    1996-08-01

    Limiting factor to computer chip speed and size is the dielectric constant of the interlayer insulating materials, which has been reduced going from inorganic to organic type materials. A further reduction, together with better mechanical properties, is still needed. We have developed a spincoating method in conjunction with a thermodynamic process (Non-solvent Induced Phase Separation) to create microporous polyimide films with both lower dielectric constant and better stress reduction properties compared to solid films. In this method, we spincoat a soluble polyimide solution in 1, 3-dimethoxybenzene solvent onto a Si wafer, and then immediately submerse the wet polymer film into a non-solvent bath, typically toluene. Phase separation of the polymer occurs on a micron size scale and the resulting microporous structure becomes locked in by the high glass transition temperature of the polyimide. Factors affecting film morphology, thickness, pore size, and % porosity include polymer concentration, spin speed, and non-solvent type. Morphology is explained in terms of thermodynamics and kinetics of phase separation and diffusion, using an idealized ternary phase diagram. One particular film having 68% porosity, 22 microns thickness, and 1.4 micron pore size had a dielectric constant of 1.88 and loss of 0.002. Stress measurements indicated that the microporous film reduced surface stress on the wafer by more than a factor of 10 compared to analogous solid polyimide film.

  3. Kinetic modelling of molecular hydrogen transport in microporous carbon materials.

    SciTech Connect

    Hankel, M.; Zhang, H.; Nguyen, T. X.; Bhatia, S. K.; Gray, S. K.; Smith, S. C.

    2011-01-01

    The proposal of kinetic molecular sieving of hydrogen isotopes is explored by employing statistical rate theory methods to describe the kinetics of molecular hydrogen transport in model microporous carbon structures. A Lennard-Jones atom-atom interaction potential is utilized for the description of the interactions between H{sub 2}/D{sub 2} and the carbon framework, while the requisite partition functions describing the thermal flux of molecules through the transition state are calculated quantum mechanically in view of the low temperatures involved in the proposed kinetic molecular sieving application. Predicted kinetic isotope effects for initial passage from the gas phase into the first pore mouth are consistent with expectations from previous modeling studies, namely, that at sufficiently low temperatures and for sufficiently narrow pore mouths D{sub 2} transport is dramatically favored over H{sub 2}. However, in contrast to expectations from previous modeling, the absence of any potential barrier along the minimum energy pathway from the gas phase into the first pore mouth yields a negative temperature dependence in the predicted absolute rate coefficients - implying a negative activation energy. In pursuit of the effective activation barrier, we find that the minimum potential in the cavity is significantly higher than in the pore mouth for nanotube-shaped models, throwing into question the common assumption that passage through the pore mouths should be the rate-determining step. Our results suggest a new mechanism that, depending on the size and shape of the cavity, the thermal activation barrier may lie in the cavity rather than at the pore mouth. As a consequence, design strategies for achieving quantum-mediated kinetic molecular sieving of H{sub 2}/D{sub 2} in a microporous membrane will need, at the very least, to take careful account of cavity shape and size in addition to pore-mouth size in order to ensure that the selective step, namely passage

  4. Improved fibroblast functionalities by microporous pattern fabricated by microelectromechanical systems.

    PubMed

    Wei, Hongbo; Zhao, Lingzhou; Chen, Bangdao; Bai, Shizhu; Zhao, Yimin

    2014-01-01

    Fibroblasts, which play an important role in biological seal formation and maintenance, determine the long-term success of percutaneous implants. In this study, well-defined microporous structures with micropore diameters of 10-60 µm were fabricated by microelectromechanical systems and their influence on the fibroblast functionalities was observed. The results show that the microporous structures with micropore diameters of 10-60 µm did not influence the initial adherent fibroblast number; however, those with diameters of 40 and 50 µm improved the spread, actin stress fiber organization, proliferation and fibronectin secretion of the fibroblasts. The microporous structures with micropore diameters of 40-50 µm may be promising for application in the percutaneous part of an implant.

  5. Detecting a single molecule using a micropore-nanopore hybrid chip

    PubMed Central

    2013-01-01

    Nanopore-based DNA sequencing and biomolecule sensing have attracted more and more attention. In this work, novel sensing devices were built on the basis of the chips containing nanopore arrays in polycarbonate (PC) membranes and micropores in Si3N4 films. Using the integrated chips, the transmembrane ionic current induced by biomolecule's translocation was recorded and analyzed, which suggested that the detected current did not change linearly as commonly expected with increasing biomolecule concentration. On the other hand, detailed translocation information (such as translocation gesture) was also extracted from the discrete current blockages in basic current curves. These results indicated that the nanofluidic device based on the chips integrated by micropores and nanopores possessed comparative potentials in biomolecule sensing. PMID:24261484

  6. Micropores and methods of making and using thereof

    DOEpatents

    Perroud, Thomas D.; Patel, Kamlesh D.; Meagher, Robert J.

    2016-08-02

    Disclosed herein are methods of making micropores of a desired height and/or width between two isotropic wet etched features in a substrate which comprises single-level isotropic wet etching the two features using an etchant and a mask distance that is less than 2.times. a set etch depth. Also disclosed herein are methods using the micropores and microfluidic devices comprising the micropores.

  7. Three-dimensional interconnected microporous poly(dimethylsiloxane) microfluidic devices.

    PubMed

    Yuen, Po Ki; Su, Hui; Goral, Vasiliy N; Fink, Katherine A

    2011-04-21

    This technical note presents a fabrication method and applications of three-dimensional (3D) interconnected microporous poly(dimethylsiloxane) (PDMS) microfluidic devices. Based on soft lithography, the microporous PDMS microfluidic devices were fabricated by molding a mixture of PDMS pre-polymer and sugar particles in a microstructured mold. After curing and demolding, the sugar particles were dissolved and washed away from the microstructured PDMS replica revealing 3D interconnected microporous structures. Other than introducing microporous structures into the PDMS replica, different sizes of sugar particles can be used to alter the surface wettability of the microporous PDMS replica. Oxygen plasma assisted bonding was used to enclose the microstructured microporous PDMS replica using a non-porous PDMS with inlet and outlet holes. A gas absorption reaction using carbon dioxide (CO(2)) gas acidified water was used to demonstrate the advantages and potential applications of the microporous PDMS microfluidic devices. We demonstrated that the acidification rate in the microporous PDMS microfluidic device was approximately 10 times faster than the non-porous PDMS microfluidic device under similar experimental conditions. The microporous PDMS microfluidic devices can also be used in cell culture applications where gas perfusion can improve cell survival and functions.

  8. Microprobes aluminosilicate ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Methods have been developed to make mixed alumina-silicate and aluminosilicate particulate microporous ceramic membranes. One method involves the making of separate alumina and silica sols which are then mixed. Another method involves the creation of a combined sol with aluminosilicate particles. The resulting combined alumina and silica membranes have high surface area, a very small pore size, and a very good temperature stability.

  9. Microporous polyimide films for reduced dielectric applications

    SciTech Connect

    Saunders, R.S.; Aubert, J.H.; McNamara, W.F.

    1995-01-01

    With all the advances in the microelectronics industry, a limiting factor to computer chip speed and size is becoming the dielectric constant of the interlayer insulating materials. Dielectric constants of these layers have been reduced in going from inorganic to organic type materials. A further reduction in dielectric constant, coupled with better mechanical properties are still required for these types of materials. The authors have developed a technique involving spincoating in conjunction with a thermodynamic process called {open_quotes}Non-solvent Induced Phase Separation{close_quotes} (NSIPS) to create microporous polyimide films that exhibit both a lower dielectric constant and better stress reduction properties compared to their solid film counterparts. In this technique, the authors spincoat a soluble polyimide solution in 1,3-dimethoxybenzene solvent onto a silicon wafer, and then immediately submerse the {open_quotes}wet{close_quotes} polymer film into a non-solvent bath, typically toluene. Phase separation of the polymer occurs on a micron size scale and the resulting microporous structure becomes locked in by the high glass transition temperature of the polyimide. The authors have determined the factors affecting the film morphology, thickness, pore size, and percent porosity; these factors include the polymer concentration, spin speed, and the type of non-solvent used. The different morphologies obtained for the varying non-solvents are explained in terms of thermodynamics and kinetics of phase separation and diffusion, using an idealized ternary phase diagram. One particular film having a porosity of 68%, thickness of 22 microns and pore size of 1.4 microns had a measured dielectric constant of 1.88 and dielectric loss of 0.002. Stress measurements indicated that the microporous film reduced surface stress on the wafer by more than a factor of 10 when compared to the analogous solid polyimide film.

  10. Thermodynamics and transport in microporous media

    SciTech Connect

    Glandt, E.D.

    1992-09-01

    Focus of this report is on the thermodynamic properties/behavior of fluids contained or adsorbed on the random microporus materials (disordered solids). The Madden-Glandt formalism for fluids in disordered matrices is applied to realistic systems (gas adsorption in carbons, polymer partitioning). Work on microgeometry of solids and their percolation and connectedness properties was continued; a study of the simplest model for microporous materials (random-pore or ''Swiss cheese'' model) was completed. Work on irreversible adsorption was continued; a simple model for correlated adsorption was studied.

  11. Mitochondrial membrane potential in single living adult rat cardiac myocytes exposed to anoxia or metabolic inhibition.

    PubMed Central

    Di Lisa, F; Blank, P S; Colonna, R; Gambassi, G; Silverman, H S; Stern, M D; Hansford, R G

    1995-01-01

    1. The relation between mitochondrial membrane potential (delta psi m) and cell function was investigated in single adult rat cardiac myocytes during anoxia and reoxygenation. delta psi m was studied by loading myocytes with JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'- tetra-ethylbenzimidazolylcarbocyanine iodide), a fluorescent probe characterized by two emission peaks (539 and 597 nm with excitation at 490 nm) corresponding to monomer and aggregate forms of the dye. 2. De-energizing conditions applied to mitochondria, cell suspensions or single cells decreased the aggregate emission and increased the monomer emission. This latter result cannot be explained by changes of JC-1 concentration in the aqueous mitochondrial matrix phase indicating that hydrophobic interaction of the probe with membranes has to be taken into account to explain JC-1 fluorescence properties in isolated mitochondria or intact cells. 3. A different sensitivity of the two JC-1 forms to delta psi m changes was shown in isolated mitochondria by the effects of ADP and FCCP and the calibration with K+ diffusion potentials. The monomer emission was responsive to values of delta psi m below 140 mV, which hardly modified the aggregate emission. Thus JC-1 represents a unique double sensor which can provide semi-quantitative information in both low and high potential ranges. 4. At the onset of glucose-free anoxia the epifluorescence of individual myocytes studied in the single excitation (490 nm)-double emission (530 and 590 nm) mode showed a gradual decline of the aggregate emission, which reached a plateau while electrically stimulated (0.2 Hz) contraction was still retained. The subsequent failure of contraction was followed by the rise of the emission at 530 nm, corresponding to the monomer form of the dye, concomitantly with the development of rigor contracture. 5. The onset of the rigor was preceded by the increase in intracellular Mg2+ concentration ([Mg2+]i) monitored by mag-indo-1 epifluorescence

  12. Immersion Calorimetry: Molecular Packing Effects in Micropores.

    PubMed

    Madani, S Hadi; Silvestre-Albero, Ana; Biggs, Mark J; Rodríguez-Reinoso, Francisco; Pendleton, Phillip

    2015-12-21

    Repeated and controlled immersion calorimetry experiments were performed to determine the specific surface area and pore-size distribution (PSD) of a well-characterized, microporous poly(furfuryl alcohol)-based activated carbon. The PSD derived from nitrogen gas adsorption indicated a narrow distribution centered at 0.57±0.05 nm. Immersion into liquids of increasing molecular sizes ranging from 0.33 nm (dichloromethane) to 0.70 nm (α-pinene) showed a decreasing enthalpy of immersion at a critical probe size (0.43-0.48 nm), followed by an increase at 0.48-0.56 nm, and a second decrease at 0.56-0.60 nm. This maximum has not been reported previously. After consideration of possible reasons for this new observation, it is concluded that the effect arises from molecular packing inside the micropores, interpreted in terms of 2D packing. The immersion enthalpy PSD was consistent with that from quenched solid density functional theory (QSDFT) analysis of the nitrogen adsorption isotherm.

  13. Immersion Calorimetry: Molecular Packing Effects in Micropores.

    PubMed

    Madani, S Hadi; Silvestre-Albero, Ana; Biggs, Mark J; Rodríguez-Reinoso, Francisco; Pendleton, Phillip

    2015-12-21

    Repeated and controlled immersion calorimetry experiments were performed to determine the specific surface area and pore-size distribution (PSD) of a well-characterized, microporous poly(furfuryl alcohol)-based activated carbon. The PSD derived from nitrogen gas adsorption indicated a narrow distribution centered at 0.57±0.05 nm. Immersion into liquids of increasing molecular sizes ranging from 0.33 nm (dichloromethane) to 0.70 nm (α-pinene) showed a decreasing enthalpy of immersion at a critical probe size (0.43-0.48 nm), followed by an increase at 0.48-0.56 nm, and a second decrease at 0.56-0.60 nm. This maximum has not been reported previously. After consideration of possible reasons for this new observation, it is concluded that the effect arises from molecular packing inside the micropores, interpreted in terms of 2D packing. The immersion enthalpy PSD was consistent with that from quenched solid density functional theory (QSDFT) analysis of the nitrogen adsorption isotherm. PMID:26394883

  14. Low aspect ratio micropores for single-particle and single-cell analysis.

    PubMed

    Goyal, Gaurav; Mulero, Rafael; Ali, Jamel; Darvish, Armin; Kim, Min Jun

    2015-05-01

    This paper describes microparticle and bacterial translocation studies using low aspect ratio solid-state micropores. Micropores, 5 μm in diameter, were fabricated in 200 nm thick free-standing silicon nitride membranes, resulting in pores with an extremely low aspect ratio, nominally 0.04. For microparticle translocation experiments, sulfonated polystyrene microparticles and magnetic microbeads in size range of 1-4 μm were used. Using the microparticle translocation characteristics, we find that particle translocations result in a change only in the pore's geometrical resistance while the access resistance remains constant. Furthermore, we demonstrate the ability of our micropore to probe high-resolution shape information of translocating analytes using concatenated magnetic microspheres. Distinct current drop peaks were observed for each microsphere of the multibead architecture. For bacterial translocation experiments, nonflagellated Escherichia coli (strain HCB 5) and wild type flagellated Salmonella typhimurium (strain SJW1103) were used. Distinct current signatures for the two bacteria were obtained and this difference in translocation behavior was attributed to different surface protein distributions on the bacteria. Our findings may help in developing low aspect ratio pores for high-resolution microparticle characterization and single-cell analysis.

  15. Dietary fat and hormonal effects on erythrocyte membrane fluidity and lipid composition in adult women.

    PubMed

    Berlin, E; Bhathena, S J; Judd, J T; Nair, P P; Jones, D Y; Taylor, P R

    1989-08-01

    Erythrocyte ghost membrane fluidity and phospholipid linoleate were significantly increased when higher levels of polyunsaturated fats were fed to healthy, free living, premenopausal women. Fluidity was assessed by diphenylhexatriene (DPH) fluorescence polarization measurements with hypotonically lysed red blood cells from 31 female subjects fed one of two sets of diets, which were formulated from typical US foods to contain polyunsaturate to saturate ratios (P/S) of 1.0 or 0.3. Both groups of women were fed diets with 40% of energy as fat for four menstrual cycles followed by low-fat diets having 20% of energy as fat for the next four menstrual cycles. Blood was sampled during the fourth cycle of each dietary period at times estimated to correspond to maximum secretions of estrogen and progesterone to assess interactive hormonal and dietary effects on membrane composition and fluidity. Red blood cell membranes were most fluid following higher levels of linoleate intake, either by higher (40%) total fat or higher P/S levels. Membrane fluidity was directly related to the phospholipid oleate and linoleate contents and inversely related to the molar cholesterol/phospholipid ratio. Hormonal status effects on the membranes were not extensive. Membrane fluidity in cells from women fed P/S = 0.3 diets was higher at 40% than at 20% fat during the luteal phase of the fourth cycle. In contrast, women fed the P/S = 1.0 diets had more fluid red cells at 40% fat during the follicular phase of the cycle. Regression analysis showed a direct linear correlation between membrane fluidity and red cell membrane insulin binding demonstrating a relation between receptor binding and cell membrane fluidity in the human female.

  16. Microporous separators for Fe/V redox flow batteries

    NASA Astrophysics Data System (ADS)

    Wei, Xiaoliang; Li, Liyu; Luo, Qingtao; Nie, Zimin; Wang, Wei; Li, Bin; Xia, Guan-Guang; Miller, Eric; Chambers, Jeff; Yang, Zhenguo

    2012-11-01

    The Fe/V redox flow battery has demonstrated promising performance with distinct advantages over other redox flow battery systems. Due to the less oxidative nature of the Fe(III) species, hydrocarbon-based ion exchange membranes or separators can be used. Daramic® microporous polyethylene separators were tested on Fe/V flow cells using sulphuric/chloric mixed acid-supporting electrolytes. Among them, separator C exhibited good flow cell cycling performance with satisfactory repeatability over a broad temperature range of 5-50 °C. Energy efficiency (EE) of C remains around 70% at current densities of 50-80 mA cm-2 in temperatures ranging from room temperature to 50 °C. The capacity decay problem could be circumvented through hydraulic pressure balancing by means of applying different pump rates to the positive and negative electrolytes. Stable capacity and energy were obtained over 20 cycles at room temperature and 40 °C. These results show that extremely low-cost separators ($1-20 m-2) are applicable in the Fe/V flow battery system with acceptable energy efficiency. This represents a remarkable breakthrough: a significant reduction of the capital cost of the Fe/V flow battery system, which could further its market penetration in grid stabilization and renewable integration.

  17. Microporous device for local electric recordings on model lipid bilayers

    NASA Astrophysics Data System (ADS)

    Kaufeld, Theresa; Steinem, Claudia; Schmidt, Christoph F.

    2015-01-01

    A powerful approach for characterizing lipid membranes and embedded proteins is the reconstitution of model lipid bilayers. The extreme fragility of 5 nm thick bilayers is a challenge for device design and requires a trade off of stability against accessibility. We here present a microporous lab-on-chip device that allows us to form stable, solvent-free lipid bilayers from giant unilamellar vesicles (GUVs) in a geometry that provides a unique set of access possibilities. The device is constructed around a micro-fabricated silicon chip with clusters of 1 µm-diameter pores and provides optical access to the lipid bilayers for high-NA epifluorescence imaging. At the same time, solvent exchange is possible on both sides of the lipid bilayer. Complete coverage can be achieved with GUVs, so that voltages can be applied across the lipid bilayer and single-channel currents can be measured using external or integrated silver/silver chloride electrodes. We describe the micro-fabrication by standard cleanroom techniques and the characterization of the device by atomic force microscopy, scanning electron microscopy and impedance spectroscopy. In proof-of-concept experiments we demonstrate that the device is capable of low-noise, single-ion-channel recordings. Electronic Supplementary Information (ESI) available: See DOI: 10.1039/b000000x/

  18. Microporous Separators for Fe/V Redox Flow Batteries

    SciTech Connect

    Wei, Xiaoliang; Li, Liyu; Luo, Qingtao; Nie, Zimin; Wang, Wei; Li, Bin; Xia, Guanguang; Miller, Eric; Chambers, Jeff; Yang, Zhenguo

    2012-06-28

    The Fe/V redox flow battery has demonstrated promising performance that is advantageous over other redox flow battery systems. The less oxidative nature of the Fe(III) species enables use of hydrocarbon - based ion exchange membranes or separators. Daramic(reg. sign) microporous polyethylene separators were tested on Fe/V flow cells using the sulphuric/chloric mixed acid - supporting electrolytes. Among them, Daramic(reg. sign) C exhibited good flow cell cycling performance with satisfactory repeatability over a broad temperature range of 5 - 50 degrees C. Energy efficiency (EE) of C remains above 67% at current densities of 50 - 80 cm{sup -2} in the temperature range from room temperature to 50 degrees C. The capacity decay problem could be circumvented through hydraulic pressure balancing by applying different pump rates to the positive and negative electrolytes. Stable capacity and energy were obtained over 40 cycles at room temperature and 40 degrees C. These results manifest that the extremely low-cost separators ($10/cm2) are applicable in the Fe/V flow battery system at an acceptable sacrifice of energy efficiency. This stands for a remarkable breakthrough in significant reduction of the capital cost of the Fe/V flow battery system, and is promising to promote its market penetration in grid stabilization and renewable integration.

  19. Poly-methyl pentene oxygenators have improved gas exchange capability and reduced transfusion requirements in adult extracorporeal membrane oxygenation.

    PubMed

    Khoshbin, Espeed; Roberts, Neil; Harvey, Chris; Machin, David; Killer, Hilliary; Peek, Giles J; Sosnowski, Andrzej W; Firmin, Richard K

    2005-01-01

    The performance of poly-methyl pentene (PMP) oxygenators (Medos Hilite 7000LT) was compared with that of silicone membrane (SM) oxygenators (Medtronic 1-4500-2A) for adult extracorporeal membrane oxygenation (ECMO). Forty consecutive patients were selected retrospectively pre- and post-introduction of PMP oxygenators. They were selected according to the dates they received ECMO and were separated into two equal groups with similar backgrounds. The flow path resistance, gas and heat exchange efficiency, consumption of coagulation factors and platelets, blood transfusion requirements, and incidence of clots for each oxygenator type was assessed. Adult PMP oxygenators showed lower blood path resistance than SM oxygenators. However, lower consumption of blood products in these oxygenators was a direct result of their smaller surface area and heparin coated design, reducing contact activation of coagulation factors. These oxygenators are noticeably smaller, require lower priming volumes, and have better gas exchange capability than SM oxygenators. They showed greater stability and preservation of coagulation factors and platelets compared with SM oxygenators. They also had the advantage of a functioning integrated heat exchanger. Using a single PMP oxygenator in the first instance may be adequate for the majority of patients and would significantly reduce red blood cell consumption during ECMO.

  20. Secretory Carrier Membrane Protein (SCAMP) deficiency influences behavior of adult flies

    PubMed Central

    Zheng, JiaLin C.; Tham, Chook Teng; Keatings, Kathleen; Fan, Steven; Liou, Angela Yen-Chun; Numata, Yuka; Allan, Douglas; Numata, Masayuki

    2014-01-01

    Secretory Carrier Membrane Proteins (SCAMPs) are a group of tetraspanning integral membrane proteins evolutionarily conserved from insects to mammals and plants. Mammalian genomes contain five SCAMP genes SCAMP1-SCAMP5 that regulate membrane dynamics, most prominently membrane-depolarization and Ca2+-induced regulated secretion, a key mechanism for neuronal and neuroendocrine signaling. However, the biological role of SCAMPs has remained poorly understood primarily owing to the lack of appropriate model organisms and behavior assays. Here we generate Drosophila Scamp null mutants and show that they exhibit reduced lifespan and behavioral abnormalities including impaired climbing, deficiency in odor associated long-term memory, and a susceptibility to heat-induced seizures. Neuron-specific restoration of Drosophila Scamp rescues all Scamp null behavioral phenotypes, indicating that the phenotypes are due to loss of neuronal Scamp. Remarkably, neuronal expression of human SCAMP genes rescues selected behavioral phenotypes of the mutants, suggesting the conserved function of SCAMPs across species. The newly developed Drosophila mutants present the first evidence that genetic depletion of SCAMP at the organismal level leads to varied behavioral abnormalities, and the obtained results indicate the importance of membrane dynamics in neuronal functions in vivo. PMID:25478561

  1. Membranous Glomerulopathy in an Adult Patient with X-Linked Agammaglobulinemia Receiving Intravenous Gammaglobulin

    PubMed Central

    Endo, LM; Giannobile, JV; Dobbs, AK; Foote, JB; Szymanska, E; Warnock, DG; Cook, WJ; Conley, ME; Schroeder, HW

    2013-01-01

    Background Immune complex deposition in the subepithelial zone of glomerular capillaries can lead to membranous glomerulopathy. Objective To present the case of a 23-year-old man with X-linked agammaglobulinemia (XLA) who developed idiopathic membranous glomerulopathy while receiving intravenous immunoglobulin (IVIG). Methods We performed an immunological workup, genetic testing, and a renal biopsy. Results XLA was confirmed with less than 0.02% CD19+ cells in the blood after sequence analysis revealed a nonfunctional BTK gene. He presented with microhematuria, which persisted for 3 years and spanned treatment with 5 different preparations of intravenous gammaglobulin. Immunohistochemistry revealed membranous glomerulopathy. Conclusion Although endogenous serum immunoglobulin (Ig) production is severely impaired in XLA, rare B lymphocytes that have managed to mature can produce functional IgG antibodies. The pathogenic immune complexes could reflect IVIG reacting with polymorphic autoantigens, an endogenous IgG-producing clone reacting with a common idiotype present in the IVIG, or both. PMID:21905506

  2. Cognitive performance in older adults is inversely associated with fish consumption but not erythrocyte membrane n-3 fatty acids.

    PubMed

    Danthiir, Vanessa; Hosking, Diane; Burns, Nicholas R; Wilson, Carlene; Nettelbeck, Ted; Calvaresi, Eva; Clifton, Peter; Wittert, Gary A

    2014-03-01

    Higher n-3 (ω-3) polyunsaturated fatty acids (PUFAs) and fish intake may help maintain cognitive function in older age. However, evidence is inconsistent; few studies have examined the relation in cognitively healthy individuals across numerous cognitive domains, and none to our knowledge have considered lifetime fish intake. We examined associations between multiple domains of cognition and erythrocyte membrane n-3 PUFA proportions and historical and contemporary fish intake in 390 normal older adults, analyzing baseline data from the Older People, Omega-3, and Cognitive Health trial. We measured n-3 PUFA in erythrocyte membranes, and we assessed historical and contemporary fish intake by food-frequency questionnaires. We assessed cognitive performance on reasoning, working memory, short-term memory, retrieval fluency, perceptual speed, simple/choice reaction time, speed of memory-scanning, reasoning speed, inhibition, and psychomotor speed. Cognitive outcomes for each construct were factor scores from confirmatory factor analysis. Multiple linear regression models controlled for a number of potential confounding factors, including age, education, sex, apolipoprotein E-ε 4 allele, physical activity, smoking, alcohol intake, socioeconomic variables, and other health-related variables. Higher erythrocyte membrane eicosapaentonoic acid proportions predicted slower perceptual and reasoning speed in females, which was attenuated once current fish intake was controlled. No other associations were present between n-3 PUFA proportions and cognitive performance. Higher current fish consumption predicted worse performance on several cognitive speed constructs. Greater fish consumption in childhood predicted slower perceptual speed and simple/choice reaction time. We found no evidence to support the hypothesis that higher proportions of long-chain n-3 fatty acids or fish intake benefits cognitive performance in normal older adults.

  3. Membranous nephropathy associated with malignant pleural mesothelioma in an adult patient: A case report

    PubMed Central

    Pu, Xinyu; Dou, Yanna; Liu, Dong; Lu, Shan; Quan, Songxia; Zhang, Xiaoxue; Ma, Shuang; Zhao, Zhanzheng

    2016-01-01

    A 23-year-old man presented to our hospital with membranous nephropathy and received a detailed examination, including pleural biopsy, due to a feeling of chest oppression. The result of the pleural biopsy was malignant pleural mesothelioma. However, the patient did not have a history of asbestos or tobacco exposure. A review of the English literature identified only 7 reported cases of concomitant malignant mesothelioma and nephrotic syndrome. Furthermore, among the 7 cases reviewed, 6 had a history of asbestos exposure, 1 had a history of prolonged tobacco exposure and in only 1 case the renal pathology results revealed the presence of membranous nephropathy. PMID:27699035

  4. Membranous nephropathy associated with malignant pleural mesothelioma in an adult patient: A case report

    PubMed Central

    Pu, Xinyu; Dou, Yanna; Liu, Dong; Lu, Shan; Quan, Songxia; Zhang, Xiaoxue; Ma, Shuang; Zhao, Zhanzheng

    2016-01-01

    A 23-year-old man presented to our hospital with membranous nephropathy and received a detailed examination, including pleural biopsy, due to a feeling of chest oppression. The result of the pleural biopsy was malignant pleural mesothelioma. However, the patient did not have a history of asbestos or tobacco exposure. A review of the English literature identified only 7 reported cases of concomitant malignant mesothelioma and nephrotic syndrome. Furthermore, among the 7 cases reviewed, 6 had a history of asbestos exposure, 1 had a history of prolonged tobacco exposure and in only 1 case the renal pathology results revealed the presence of membranous nephropathy.

  5. MEMBRANE BIOTREATMENT OF VOC-LADEN AIR

    EPA Science Inventory

    The paper discusses membrane biotreatment of air laden with volatile organic compounds (VOCs). Microporous flat-sheet and hollow-fiber membrane contactors were used to support air-liquid mass transfer interfaces. These modules were used in a two-step process to transfer VOCs fr...

  6. Structure and Capacitance of Electrical Double Layers inside Micropores

    NASA Astrophysics Data System (ADS)

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Sumpter, Bobby G.; Meunier, Vincent

    2010-03-01

    Recent experiments indicate that the specific capacitance of micropores (diameter less than 2nm) increases anomalously as the pore size decreases^[1]. To understand the physical origin of this discovery, we performed a series of molecular dynamics simulations to study the electrical double layers (EDLs) in micropores with different shapes (tube vs slit) and pore sizes (0.668nm - 3.342nm). Several different aqueous electrolytes (K^+, Na^+, Cl^-, and F^- in water) were used in these micropores. We quantified the structure of EDLs inside the pores, and computed the capacitance of EDLs. The scaling of capacitance shows a qualitative agreement with the experimental observations. We attribute the anomalous enhancement of capacitance in micropores to the short-range ionelectrode and ionsolvent interactions.[1] J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, and P.L. Taberna, Science 2006, 313, 1760.

  7. Supercritical Processing of Functionalized Size Selective Microporous Materials

    SciTech Connect

    Shin, Yongsoon; Zemanian, Thomas S.; Fryxell, Glen E.; Wang, Li Q.; Liu, Jun

    2000-05-01

    Zeolites and related microporous materials are qidely used in industry as size selective catalysts due to the uniform pore size and shape. The modification of such materials by organic funtional molecules will greatly broaden the application.

  8. Microporous polymer films and methods of their production

    DOEpatents

    Aubert, J.H.

    1995-06-06

    A process is described for producing thin microporous polymeric films for a variety of uses. The process utilizes a dense gas (liquefied gas or supercritical fluid) selected to combine with a solvent-containing polymeric film so that the solvent is dissolved in the dense gas, the polymer is substantially insoluble in the dense gas, and two phases are formed. A microporous film is obtained by removal of a dense gas-solvent phase. 9 figs.

  9. Fluoride-assisted synthesis of bimodal microporous SSZ-13 zeolite.

    PubMed

    Zhu, Xiaochun; Kosinov, Nikolay; Hofmann, Jan P; Mezari, Brahim; Qian, Qingyun; Rohling, Roderigh; Weckhuysen, Bert M; Ruiz-Martínez, Javier; Hensen, Emiel J M

    2016-02-21

    The presence of small amount of fluoride in alkaline hydrothermal synthesis of SSZ-13 zeolite yields bimodal microporous particles with substantially improved performance in the methanol-to-olefins (MTO) reaction. Hydrocarbon uptake measurements and fluorescence microspectroscopy of spent catalysts demonstrate enhanced diffusion through micropores at the grain boundaries of nanocrystals running through the zeolite particles. Fluoride-assisted SSZ-13 synthesis is a cheap and scalable approach to optimize the performance of MTO zeolite catalysts. PMID:26810114

  10. Diclofenac delays micropore closure following microneedle treatment in human subjects.

    PubMed

    Brogden, Nicole K; Milewski, Mikolaj; Ghosh, Priyanka; Hardi, Lucia; Crofford, Leslie J; Stinchcomb, Audra L

    2012-10-28

    Drugs absorbed poorly through the skin are commonly delivered via injection with a hypodermic needle, which is painful and increases the risk of transmitting infectious diseases. Microneedles (MNs) selectively and painlessly permeabilize the outermost skin layer, allowing otherwise skin-impermeable drugs to cross the skin through micron-sized pores and reach therapeutic concentrations. However, rapid healing of the micropores prevents further drug delivery, blunting the clinical utility of this unique transdermal technique. We present the first human study demonstrating that micropore lifetime can be extended following MN treatment. Subjects received one-time MN treatment and daily topical application of diclofenac sodium. Micropore closure was measured with impedance spectroscopy, and area under the admittance-time curve (AUC) was calculated. AUC was significantly higher at MN+diclofenac sodium sites vs. placebo, suggesting slower rates of micropore healing. Colorimetry measurements confirmed the absence of local erythema and irritation. This mechanistic human proof-of-concept study demonstrates that micropore lifetime can be prolonged with simple topical administration of a non-specific cyclooxygenase inhibitor, suggesting the involvement of subclinical inflammation in micropore healing. These results will allow for longer patch wear time with MN-enhanced delivery, thus increasing patient compliance and expanding the transdermal field to a wider variety of clinical conditions. PMID:22929967

  11. Water-Dispersible, Responsive, and Carbonizable Hairy Microporous Polymeric Nanospheres.

    PubMed

    Mai, Weicong; Sun, Bin; Chen, Luyi; Xu, Fei; Liu, Hao; Liang, Yeru; Fu, Ruowen; Wu, Dingcai; Matyjaszewski, Krzysztof

    2015-10-21

    Multifunctionalization of microporous polymers is highly desirable but remains a significant challenge, considering that the current microporous polymers are generally hydrophobic and nonresponsive to different environmental stimuli and difficult to be carbonized without damage of their well-defined nanomorphology. Herein, we demonstrate a facile and versatile method to fabricate water-dispersible, pH/temperature responsive and readily carbonizable hairy microporous polymeric nanospheres based on combination of the hyper-cross-linking chemistry with the surface-initiated atom transfer radical polymerization (SI-ATRP). The hyper-cross-linking creates a highly microporous core, whereas the SI-ATRP provides diverse functionalities by surface grafting of hairy functional blocks. The as-prepared materials present multifunctional properties, including sensitive response to pH/temperature, high adsorption capacity toward adsorbates from aqueous solution, and valuable transformation into well-defined microporous carbon nanospheres because of hybrid of carbonizable core and thermo-decomposable protection shell. We hope this strategy could promote the development of both functional microporous polymers and advanced hairy nanoparticles for multipurpose applications.

  12. SANS Investigations of CO2 Adsorption in Microporous Carbon

    DOE PAGES

    Bahadur, Jitendra; Melnichenko, Yuri B.; He, Lilin; Contescu, Cristian I.; Gallego, Nidia C.; Carmichael, Justin R.

    2015-08-07

    The high pressure adsorption behavior of CO2 at T = 296 K in microporous carbon was investigated by small-angle neutron scattering (SANS) technique. A strong densification of CO2 in micropores accompanied by non-monotonic adsorption-induced pore deformation was observed. The density of confined CO2 increases rapidly with pressure and reaches the liquid –like density at 20 bar, which corresponds to the relative pressure of P/Psat ~0.3. At P > 20 bar density of confined CO2 increases slowly approaching a plateau at higher pressure. The size of micropores first increases with pressure, reaches a maximum at 20 bar,more » and then decreases with pressure. A complementary SANS experiment conducted on the same microporous carbon saturated with neutron-transparent and non-adsorbing inert gas argon shows no deformation of micropores at pressures up to ~200 bars. This result demonstrates that the observed deformation of micropores in CO2 is an adsorption-induced phenomenon, caused by the solvation pressure - induced strain and strong densification of confined CO2 .« less

  13. Microporous Cell-laden Hydrogels for Engineered Tissue Constructs

    PubMed Central

    Park, Jae Hong; Chung, Bong Geun; Lee, Won Gu; Kim, Jinseok; Brigham, Mark D.; Shim, Jaesool; Lee, Seunghwan; Hwang, Changmo; Durmus, Naside Gozde; Demirci, Utkan; Khademhosseini, Ali

    2010-01-01

    In this paper, we describe an approach to generate microporous cell-laden hydrogels for fabricating biomimetic tissue engineered constructs. Micropores at different length scales were fabricated in cell-laden hydrogels by micromolding fluidic channels and leaching sucrose crystals. Microengineered channels were created within cell-laden hydrogel precursors that contained agarose solution mixed with sucrose crystals. The rapid cooling of the agarose solution was used to gel the solution and form micropores in place of the sucrose crystals. The sucrose leaching process generated micropores that were homogeneously distributed within the gels, while enabling the direct immobilization of cells within the gels. We also characterized the physical, mechanical, and biological properties (i.e. microporosity, diffusivity, and cell viability) of cell-laden agarose gels as a function of engineered porosity. The microporosity was controlled from 0% to 40% and the diffusivity of molecules in the porous agarose gels increased as compared to controls. Furthermore, the viability of human hepatocyte cells that were cultured in microporous agarose gels corresponded to the diffusion profile generated away from the microchannels. Based on their enhanced diffusive properties, microporous cell-laden hydrogels containing a microengineered fluidic channel could be a useful tool for generating tissue structures for regenerative medicine and drug discovery applications. PMID:20091766

  14. Nanofiber based triple layer hydro-philic/-phobic membrane - a solution for pore wetting in membrane distillation

    NASA Astrophysics Data System (ADS)

    Prince, J. A.; Rana, D.; Matsuura, T.; Ayyanar, N.; Shanmugasundaram, T. S.; Singh, G.

    2014-11-01

    The innovative design and synthesis of nanofiber based hydro-philic/phobic membranes with a thin hydro-phobic nanofiber layer on the top and a thin hydrophilic nanofiber layer on the bottom of the conventional casted micro-porous layer which opens up a solution for membrane pore wetting and improves the pure water flux in membrane distillation.

  15. Nanofiber based triple layer hydro-philic/-phobic membrane--a solution for pore wetting in membrane distillation.

    PubMed

    Prince, J A; Rana, D; Matsuura, T; Ayyanar, N; Shanmugasundaram, T S; Singh, G

    2014-01-01

    The innovative design and synthesis of nanofiber based hydro-philic/phobic membranes with a thin hydro-phobic nanofiber layer on the top and a thin hydrophilic nanofiber layer on the bottom of the conventional casted micro-porous layer which opens up a solution for membrane pore wetting and improves the pure water flux in membrane distillation. PMID:25377488

  16. Nanofiber based triple layer hydro-philic/-phobic membrane - a solution for pore wetting in membrane distillation

    PubMed Central

    Prince, J. A.; Rana, D.; Matsuura, T.; Ayyanar, N.; Shanmugasundaram, T. S.; Singh, G.

    2014-01-01

    The innovative design and synthesis of nanofiber based hydro-philic/phobic membranes with a thin hydro-phobic nanofiber layer on the top and a thin hydrophilic nanofiber layer on the bottom of the conventional casted micro-porous layer which opens up a solution for membrane pore wetting and improves the pure water flux in membrane distillation. PMID:25377488

  17. Membranes in Lithium Ion Batteries

    PubMed Central

    Yang, Min; Hou, Junbo

    2012-01-01

    Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some selected membranes in lithium ion batteries. Based on the type of electrolyte used, literature concerning ceramic-glass and polymer solid ion conductors, microporous filter type separators and polymer gel based membranes is reviewed. PMID:24958286

  18. Conjugated microporous polymers: design, synthesis and application.

    PubMed

    Xu, Yanhong; Jin, Shangbin; Xu, Hong; Nagai, Atsushi; Jiang, Donglin

    2013-10-21

    Conjugated microporous polymers (CMPs) are a class of organic porous polymers that combine π-conjugated skeletons with permanent nanopores, in sharp contrast to other porous materials that are not π-conjugated and with conventional conjugated polymers that are nonporous. As an emerging material platform, CMPs offer a high flexibility for the molecular design of conjugated skeletons and nanopores. Various chemical reactions, building blocks and synthetic methods have been developed and a broad variety of CMPs with different structures and specific properties have been synthesized, driving the rapid growth of the field. CMPs are unique in that they allow the complementary utilization of π-conjugated skeletons and nanopores for functional exploration; they have shown great potential for challenging energy and environmental issues, as exemplified by their excellent performance in gas adsorption, heterogeneous catalysis, light emitting, light harvesting and electrical energy storage. This review describes the molecular design principles of CMPs, advancements in synthetic and structural studies and the frontiers of functional exploration and potential applications.

  19. [Extracorporeal membrane oxygenation for treatment of acute respiratory failure in adults].

    PubMed

    Pedersen, Charles Marinus; Jensen, Reinhold; Lindskov, Christian

    2016-09-19

    Extracorporeal membrane oxygenation (ECMO) can support gas exchange independently of mechanical ventilation in patients with severe acute respiratory failure. Veno-venous ECMO is a temporary technique for providing life support by pulmonary dysfunction. ECMO should be considered for patients with respiratory failure when they cannot survive with conventional therapy. ECMO may be used either as a rescue therapy or to prevent ventilator-associated lung injury. Exact criteria for ECMO are not available. Transportation while using ECMO is safe when a team from the management centre provides it. PMID:27649710

  20. DEMONSTRATION OF PILOT-SCALE PERVAPORATION SYSTEMS FOR VOLATILE ORGANIC COMPOUND REMOVAL FROM A SURFACTANT ENHANCED AQUIFER REMEDIATION FLUID. II. HOLLOW FIBER MEMBRANE MODULES

    EPA Science Inventory

    Pilot-scale demonstration of pervaporation-based removal of volatile organic compounds from a surfactant enhanced aquifer remediation (SEAR) fluid has been conducted at USEPA's Test & Evaluation Facility using hollow fiber membrane modules. The membranes consisted of microporous...

  1. Expression of nestin, mesothelin and epithelial membrane antigen (EMA) in developing and adult human meninges and meningiomas.

    PubMed

    Petricevic, Josko; Forempoher, Gea; Ostojic, Ljerka; Mardesic-Brakus, Snjezana; Andjelinovic, Simun; Vukojevic, Katarina; Saraga-Babic, Mirna

    2011-11-01

    The spatial and temporal pattern of appearance of nestin, epithelial membrane antigen (EMA) and mesothelin proteins was immunohistochemically determined in the cells of normal developing and adult human meninges and meningiomas. Human meninges developed as two mesenchymal condensations in the head region. The simple squamous epithelium on the surface of leptomeninges developed during mesenchymal to epithelial transformation. Nestin appeared for the first time in week 7, EMA in week 8, while mesothelin appeared in week 22 of development. In the late fetal period and after birth, nestin expression decreased, whereas expression of EMA and mesothelin increased. EMA appeared in all surface epithelial cells and nodules, while mesothelin was found only in some of them. In adult meninges, all three proteins were predominantly localized in the surface epithelium and meningeal nodules. In meningothelial meningiomas (WHO grade I), EMA was detected in all tumor cells except in the endothelial cells, mesothelin characterized nests of tumor cells, while nestin was found predominantly in the walls of blood vessels. The distribution pattern of those proteins in normal meningeal and tumor cells indicates that nestin might characterize immature cells, while EMA and mesothelin appeared in maturing epithelial cells. Neoplastic transformation of these specific cell lineages contributes to the cell population in meningiomas.

  2. Seroepidemiology of varicella-zoster virus in Korean adolescents and adults using fluorescent antibody to membrane antigen test.

    PubMed

    Han, S B; Kang, K R; Huh, D H; Lee, H C; Kim, J H; Kang, J H; Ma, S H

    2015-06-01

    We conducted a cross-sectional seroepidemiological study in 2012-2013 to determine the seroprevalence of varicella-zoster virus (VZV) in adolescents and adults living in Korea, where varicella vaccination has been recommended universally at age 12-15 months since 2005. Residual serum samples were collected from 1196 healthy adults and adolescents aged ⩾10 years between November 2012 and March 2013. The fluorescent antibody to membrane antigen (FAMA) test and enzyme-linked immunosorbent assay (ELISA) were performed to determine the seroprevalence of VZV. The seroprevalences of VZV were compared between six age groups: 10-19, 20-29, 30-39, 40-49, 50-59, and ⩾60 years. The seroprevalence of VZV in the entire study cohort was 99·1% according to the FAMA test and 93·1% as determined by ELISA. The seroprevalences of the six age groups were as follows: 96·0%, 99·5%, 99·5%, 99·5%, 100%, and 100%, respectively, by the FAMA test, and 83·3%, 93·0%, 93·0%, 97·5%, 94·5%, and 97·5%, respectively, by ELISA. Seroprevalence increased significantly with age (P < 0·001); moreover, the seroprevalence in subjects aged 10-19 years was significantly lower than in other age groups (P < 0·001), as measured by both the FAMA test and ELISA. Thus, strategies to increase protective immunity against VZV in teenagers are necessary.

  3. Position paper for the organization of extracorporeal membrane oxygenation programs for acute respiratory failure in adult patients.

    PubMed

    Combes, Alain; Brodie, Daniel; Bartlett, Robert; Brochard, Laurent; Brower, Roy; Conrad, Steve; De Backer, Daniel; Fan, Eddy; Ferguson, Niall; Fortenberry, James; Fraser, John; Gattinoni, Luciano; Lynch, William; MacLaren, Graeme; Mercat, Alain; Mueller, Thomas; Ogino, Mark; Peek, Giles; Pellegrino, Vince; Pesenti, Antonio; Ranieri, Marco; Slutsky, Arthur; Vuylsteke, Alain

    2014-09-01

    The use of extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure (ARF) in adults is growing rapidly given recent advances in technology, even though there is controversy regarding the evidence justifying its use. Because ECMO is a complex, high-risk, and costly modality, at present it should be conducted in centers with sufficient experience, volume, and expertise to ensure it is used safely. This position paper represents the consensus opinion of an international group of physicians and associated health-care workers who have expertise in therapeutic modalities used in the treatment of patients with severe ARF, with a focus on ECMO. The aim of this paper is to provide physicians, ECMO center directors and coordinators, hospital directors, health-care organizations, and regional, national, and international policy makers a description of the optimal approach to organizing ECMO programs for ARF in adult patients. Importantly, this will help ensure that ECMO is delivered safely and proficiently, such that future observational and randomized clinical trials assessing this technique may be performed by experienced centers under homogeneous and optimal conditions. Given the need for further evidence, we encourage restraint in the widespread use of ECMO until we have a better appreciation for both the potential clinical applications and the optimal techniques for performing ECMO.

  4. Developing a simple preinterventional score to predict hospital mortality in adult venovenous extracorporeal membrane oxygenation: A pilot study.

    PubMed

    Cheng, Yu-Ting; Wu, Meng-Yu; Chang, Yu-Sheng; Huang, Chung-Chi; Lin, Pyng-Jing

    2016-07-01

    Despite gaining popularity, venovenous extracorporeal membrane oxygenation (VV-ECMO) remains a controversial therapy for acute respiratory failure (ARF) in adult patients due to its equivocal survival benefits. The study was aimed at identifying the preinterventional prognostic predictors of hospital mortality in adult VV-ECMO patients and developing a practical mortality prediction score to facilitate clinical decision-making.This retrospective study included 116 adult patients who received VV-ECMO for severe ARF in a tertiary referral center, from 2007 to 2015. The definition of severe ARF was PaO2/ FiO2 ratio < 70 mm Hg under advanced mechanical ventilation (MV). Preinterventional variables including demographic characteristics, ventilatory parameters, and severity of organ dysfunction were collected for analysis. The prognostic predictors of hospital mortality were generated with multivariate logistic regression and transformed into a scoring system. The discriminative power on hospital mortality of the scoring system was presented as the area under receiver operating characteristic curve (AUROC).The overall hospital mortality rate was 47% (n = 54). Pre-ECMO MV day > 4 (OR: 4.71; 95% CI: 1.98-11.23; P < 0.001), pre-ECMO sequential organ failure assessment (SOFA) score >9 (OR: 3.16; 95% CI: 1.36-7.36; P = 0.01), and immunocompromised status (OR: 2.91; 95% CI: 1.07-7.89; P = 0.04) were independent predictors of hospital mortality of adult VV-ECMO. A mortality prediction score comprising of the 3 binary predictors was developed and named VV-ECMO mortality score. The total score was estimated as follows: VV-ECMO mortality score = 2 × (Pre-ECMO MV day > 4) + 1 × (Pre-ECMO SOFA score >9) + 1 × (immunocompromised status). The AUROC of VV-ECMO mortality score was 0.76 (95% CI: 0.67-0.85; P < 0.001). The corresponding hospital mortality rates to VV-ECMO mortality scores were 18% (Score 0), 35% (Score 1), 56% (Score 2), 75% (Score

  5. Characterization of ion channels on the surface membrane of adult rat skeletal muscle.

    PubMed Central

    Chua, M; Betz, W J

    1991-01-01

    The channels present on the surface membrane of isolated rat flexor digitorum brevis muscle fibers were surveyed using the patch clamp technique. 85 out of 139 fibers had a novel channel which excluded the anions chloride, sulfate, and isethionate with a permeability ratio of chloride to sodium of less than 0.05. The selectivity sequence for cations was Na+ = K+ = Cs+ greater than Ca++ = Mg++ greater than N-Methyl-D-Glucamine. The channel remained closed for long periods, and had a large conductance of approximately 320 pS with several subconductance states at approximately 34 pS levels. Channel activity was not voltage dependent and the reversal potential for cations in muscle fibers of approximately 0 mV results in the channel's behaving as a physiological leakage conductance. Voltage activated potassium channels were present in 65 of the cell attached patches and had conductances of mostly 6, 12, and 25 pS. The voltage sensitivity of the potassium channels was consistent with that of the delayed rectifier current. Only three patches contained chloride channels. The scarcity of chloride channels despite the known high chloride conductance of skeletal muscle suggests that most of the chloride channels must be located in the transverse tubular system. PMID:1714780

  6. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers.

    PubMed

    Xu, Lai; Li, Youyong

    2016-06-30

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers.

  7. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers

    PubMed Central

    Xu, Lai; Li, Youyong

    2016-01-01

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers. PMID:27356483

  8. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers

    NASA Astrophysics Data System (ADS)

    Xu, Lai; Li, Youyong

    2016-06-01

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers.

  9. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers.

    PubMed

    Xu, Lai; Li, Youyong

    2016-01-01

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers. PMID:27356483

  10. Adult venovenous extracorporeal membrane oxygenation for severe respiratory failure: Current status and future perspectives.

    PubMed

    Sen, Ayan; Callisen, Hannelisa E; Alwardt, Cory M; Larson, Joel S; Lowell, Amelia A; Libricz, Stacy L; Tarwade, Pritee; Patel, Bhavesh M; Ramakrishna, Harish

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration. PMID:26750681

  11. Adult venovenous extracorporeal membrane oxygenation for severe respiratory failure: Current status and future perspectives

    PubMed Central

    Sen, Ayan; Callisen, Hannelisa E.; Alwardt, Cory M.; Larson, Joel S.; Lowell, Amelia A.; Libricz, Stacy L.; Tarwade, Pritee; Patel, Bhavesh M.; Ramakrishna, Harish

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration. PMID:26750681

  12. Effects of phytanic acid on the vitamin E status, lipid composition and physical properties of retinal cell membranes: implications for adult Refsum disease.

    PubMed

    Young, S P; Johnson, A W; Muller, D P

    2001-12-01

    Adult Refsum disease is an inherited disorder in which phytanic acid accumulates in tissues and serum. Two hypotheses have been proposed to explain the pathogenesis of this condition. The molecular distortion hypothesis suggests that phytanic acid may alter membrane composition and structure, thereby affecting membrane function(s). The anti-metabolite hypothesis suggests that an accumulation of phytanic acid in membranes may interfere with vitamin E function. These two hypotheses were investigated by studying the effects of modulating phytanic acid and alpha-tocopherol concentrations on the fatty acid composition and certain physical parameters of cultured retinal cells. Results showed that (a) the phospholipid fraction of retinal cells readily incorporated phytanic acid, (b) the incorporation of phytanic acid increased membrane fluidity, (c) there was no competition for uptake between phytanic acid and alpha-tocopherol, and (d) the incorporation of phytanic acid did not increase the susceptibility of membranes to lipid peroxidation in vitro. These results obtained with cultured retinal cells suggest that the molecular distortion hypothesis, but not the anti-metabolite hypothesis, could explain the pathogenesis of adult Refsum disease. In vitro tissue culture models can, however, only approximate to the much more complex situation that occurs in vivo.

  13. Distribution and Speciation of Nutrient Elements around Micropores

    SciTech Connect

    Jassogne, Laurence; Hettiarachchi, Ganga; Chittleborough, David; McNeill, Ann

    2009-07-21

    In Australia a class of soils known as duplex soils covers approximately 20% of the continent. Their defining characteristic is a sharp texture contrast between the A (or E) and B horizon. The upper B horizon at the point of contact with the E horizon is often highly sodic and of such a high strength that root growth and proliferation, water conductivity, aeration, water storage, and water uptake are restricted. Roots growing in these soils rely on channels created by previous roots or cracks arising from shrink-swell forces associated with seasonal wetting and drying. Although the characteristics of rhizospheres compared with the soil matrix are well documented there is a paucity of knowledge about how long these changes persist after roots decay. This knowledge is fundamental to our understanding of root growth in duplex soils in which plants rely on pore networks formed by previous plants to proliferate in the subsoil. In this study we investigated the heterogeneous chemistry of micropores in situ using synchrotron-based {mu}-x-ray fluorescence spectroscopy (XRF), {mu}-x-ray absorption near edge structure spectroscopy (XANES), and extended {mu}-x-ray absorption fine structure spectroscopy (EXAFS). The distribution maps of Ca, Mn, Fe, Cu, and Zn at micrometer resolution were collected using {mu}-XRF. Subsequently, specific locations with higher concentrations (hot spots) of Mn, Fe, Cu, or Zn were selected and XANES and EXAFS spectra were collected to study the speciation of these elements around the micropore compared with the soil matrix. The {mu}-XRF maps showed that Mn was depleted around one of the micropores studied but accumulated around another micropore. Copper and Zn accumulated around the micropores, whereas Ca was predominantly inside micropores. There was no difference between matrix and micropore surface with respect to the distribution of Fe. Around micropores Mn was present in reduced form (Mn II) and Fe was in its oxidized form (Fe III). Manganese

  14. Ionomer-Membrane Water Processing Apparatus

    NASA Technical Reports Server (NTRS)

    MacCallum, Taber K. (Inventor); Kelsey, Laura (Inventor)

    2016-01-01

    This disclosure provides water processing apparatuses, systems, and methods for recovering water from wastewater such as urine. The water processing apparatuses, systems, and methods can utilize membrane technology for extracting purified water in a single step. A containment unit can include an ionomer membrane, such as Nafion(Registered Trademark), over a hydrophobic microporous membrane, such as polytetrafluoroethylene (PTFE). The containment unit can be filled with wastewater, and the hydrophobic microporous membrane can be impermeable to liquids and solids of the wastewater but permeable to gases and vapors of the wastewater, and the ionomer membrane can be permeable to water vapor but impermeable to one or more contaminants of the gases and vapors. The containment unit can be exposed to a dry purge gas to maintain a water vapor partial pressure differential to drive permeation of the water vapor, and the water vapor can be collected and processed into potable water.

  15. The adult brain tissue response to hollow fiber membranes of varying surface architecture with or without cotransplanted cells

    NASA Astrophysics Data System (ADS)

    Zhang, Ning

    A variety of biomaterials have been chronically implanted into the central nervous system (CNS) for repair or therapeutic purposes. Regardless of the application, chronic implantation of materials into the CNS induces injury and elicits a wound healing response, eventually leading to the formation of a dense extracellular matrix (ECM)-rich scar tissue that is associated with the segregation of implanted materials from the surrounding normal tissue. Often this reaction results in impaired performance of indwelling CNS devices. In order to enhance the performance of biomaterial-based implantable devices in the CNS, this thesis investigated whether adult brain tissue response to implanted biomaterials could be manipulated by changing biomaterial surface properties or further by utilizing the biology of co-transplanted cells. Specifically, the adult rat brain tissue response to chronically implanted poly(acrylonitrile-vinylchloride) (PAN-PVC) hollow fiber membranes (HFMs) of varying surface architecture were examined temporally at 2, 4, and 12 weeks postimplantation. Significant differences were discovered in the brain tissue response to the PAN-PVC HFMs of varying surface architecture at 4 and 12 weeks. To extend this work, whether the soluble factors derived from a co-transplanted cellular component further affect the brain tissue response to an implanted HFM in a significant way was critically exploited. The cells used were astrocytes, whose ability to influence scar formation process following CNS injury by physical contact with the host tissue had been documented in the literature. Data indicated for the first time that astrocyte-derived soluble factors ameliorate the adult brain tissue reactivity toward HFM implants in an age-dependent manner. While immature astrocytes secreted soluble factors that suppressed the brain tissue reactivity around the implants, mature astrocytes secreted factors that enhanced the gliotic response. These findings prove the feasibility

  16. Performance Evaluation of Microporous Separator in Fe/V Redox Flow Battery

    SciTech Connect

    Wei, Xiaoliang; Luo, Qingtao; Li, Bin; Nie, Zimin; Miller, Eric; Chambers, Jeff; Sprenkle, Vincent L.; Wang, Wei

    2013-04-08

    The newly developed Fe/V redox flow battery has demonstrated attractive cell performance. However, the deliverable energy density is relatively inferior due to the low cell voltage. To compensate this disadvantage and compete with other redox flow battery systems, cost reduction of the Fe/V system is necessary. This paper describes evaluation of hydrocarbon-based Daramic® microporous separators for use in the Fe/V system. The separator B having ion exchange capacity demonstrated excellent capacity retention capability. Separator B exhibited energy efficiency above 65% over a broad temperature range of 5-50oC and at current densities up to 80mA/cm2. Plus, separator B is very inexpensive and has exceptional mechanical properties. Therefore, this separator shows great potential to replace the expensive Nafion® membrane. This will drive down the capital cost and make the Fe/V system a promising low-cost energy storage technology.

  17. Rendering non-energetic microporous coordination polymers explosive.

    PubMed

    McDonald, Kyle A; Bennion, Jonathan C; Leone, Amanda K; Matzger, Adam J

    2016-09-18

    Adsorption of oxidizing guest molecules into a non-energetic microporous coordination polymer produces explosives with desirable oxygen balance, high heat released upon decomposition, and suppressed vapor pressure of the guest. Here, this results in primary explosives, materials very sensitive to impact, that have the potential to be used as replacements for lead-based initiators.

  18. Anisotropic microporous supports impregnated with polymeric ion-exchange materials

    DOEpatents

    Friesen, Dwayne; Babcock, Walter C.; Tuttle, Mark

    1985-05-07

    Novel ion-exchange media are disclosed, the media comprising polymeric anisotropic microporous supports containing polymeric ion-exchange or ion-complexing materials. The supports are anisotropic, having small exterior pores and larger interior pores, and are preferably in the form of beads, fibers and sheets.

  19. Anisotropic microporous supports impregnated with polymeric ion-exchange materials

    DOEpatents

    Friesen, D.; Babcock, W.C.; Tuttle, M.

    1985-05-07

    Novel ion-exchange media are disclosed, the media comprising polymeric anisotropic microporous supports containing polymeric ion-exchange or ion-complexing materials. The supports are anisotropic, having small exterior pores and larger interior pores, and are preferably in the form of beads, fibers and sheets. 5 figs.

  20. Rendering non-energetic microporous coordination polymers explosive.

    PubMed

    McDonald, Kyle A; Bennion, Jonathan C; Leone, Amanda K; Matzger, Adam J

    2016-09-18

    Adsorption of oxidizing guest molecules into a non-energetic microporous coordination polymer produces explosives with desirable oxygen balance, high heat released upon decomposition, and suppressed vapor pressure of the guest. Here, this results in primary explosives, materials very sensitive to impact, that have the potential to be used as replacements for lead-based initiators. PMID:27523573

  1. Fundamental Studies of Crystal Growth of Microporous Materials

    NASA Technical Reports Server (NTRS)

    Singh, Ramsharan; Doolittle, John, Jr.; Payra, Pramatha; Dutta, Prabir K.; George, Michael A.; Ramachandran, Narayanan; Schoeman, Brian J.

    2003-01-01

    Microporous materials are framework structures with well-defined porosity, often of molecular dimensions. Zeolites contain aluminum and silicon atoms in their framework and are the most extensively studied amongst all microporous materials. Framework structures with P, Ga, Fe, Co, Zn, B, Ti and a host of other elements have also been made. Typical synthesis of microporous materials involve mixing the framework elements (or compounds, thereof) in a basic solution, followed by aging in some cases and then heating at elevated temperatures. This process is termed hydrothermal synthesis, and involves complex chemical and physical changes. Because of a limited understanding of this process, most synthesis advancements happen by a trial and error approach. There is considerable interest in understanding the synthesis process at a molecular level with the expectation that eventually new framework structures will be built by design. The basic issues in the microporous materials crystallization process include: (a) Nature of the molecular units responsible for the crystal nuclei formation; (b) Nature of the nuclei and nucleation process; (c) Growth process of the nuclei into crystal; (d) Morphological control and size of the resulting crystal; (e) Surface structure of the resulting crystals; and (f) Transformation of frameworks into other frameworks or condensed structures.

  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. Supported liquid membranes

    SciTech Connect

    Danesi, P.R.

    1984-01-01

    The possibility of utilizing thin layers of organic solutions of solvent extraction reagents, immobilized on microporous inert supports interposed between two aqueous solutions, for selectively removing metal ions from a mixture represents an attractive alternative to liquid-liquid extraction. A detailed knowledge of the liquid-liquid extraction equilibria and mass transfer kinetics is required to understand and to describe quantitatively the rate laws which control the permeation of metal species through Supported Liquid Membranes (SLM) and to exploit them for separation processes. This paper attempts to understand the mechanism of transport through SLM.

  4. Yeast-based microporous carbon materials for carbon dioxide capture.

    PubMed

    Shen, Wenzhong; He, Yue; Zhang, Shouchun; Li, Junfen; Fan, Weibin

    2012-07-01

    A hierarchical microporous carbon material with a Brunauer-Emmett-Teller surface area of 1348 m(2) g(-1) and a pore volume of 0.67 cm(3) g(-1) was prepared from yeast through chemical activation with potassium hydroxide. This type of material contains large numbers of nitrogen-containing groups (nitrogen content >5.3 wt%), and, consequently, basic sites. As a result, this material shows a faster adsorption rate and a higher adsorption capacity of CO(2) than the material obtained by directly carbonizing yeast under the same conditions. The difference is more pronounced in the presence of N(2) or H(2)O, showing that chemical activation of discarded yeast with potassium hydroxide could afford high-performance microporous carbon materials for the capture of CO(2).

  5. Reverse Micelle Based Synthesis of Microporous Materials in Microgravity

    NASA Technical Reports Server (NTRS)

    Dutta, Prabir K.

    2001-01-01

    Microporous materials include a large group of solids of varying chemical composition as well as porosity. These materials are characterized by channels and cavities of molecular dimensions. The framework structure is made up of interconnecting T-O-T' bonds, where T and T' can be Si, Al, P, Ga, Fe, Co, Zn, B and a host of other elements. Materials with Si-O-Al bonding in the framework are called zeolites and are extensively used in many applications. Ion-exchange properties of these materials are exploited in the consumer and environmental industries. Chemical and petroleum industries use zeolites as catalysts in hydrocarbon transform ations. Synthesis of new microporous frameworks has led to the development of new technologies, and thus considerable effort worldwide is expended in their discovery. Microporous materials are typically made under hydrothermal conditions. Influence of nature of starting reactants, structure directing agents, pH, temperature, and aging all have profound influence on the synthesis process. This is primarily because the most interesting open frameworks are not necessarily the stable structures in the reaction medium. Thus, the discovery of new frameworks is often tied to finding the right composition and synthesis conditions that allow for kinetic stabilization of the structure. This complexity of the synthesis process and limited understanding of it has made it difficult to develop directed is of microporous materials and most advances in this field have been made by trial and error. The basic issues in crystal growth of these materials include: (1) Nature of the nucleation process; (2) Molecular structure and assembly of nuclei; (3) Growth of nuclei into crystals; (4) Morphology control; and (5) Transformation of frameworks into other structures. The NASA-funded research described in this paper focuses on all the above issues and has been described in several publications. We present the highlights of our program, especially with the

  6. Fundamental Studies of Crystal Growth of Microporous Materials

    NASA Technical Reports Server (NTRS)

    Dutta, P.; George, M.; Ramachandran, N.; Schoeman, B.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Microporous materials are framework structures with well-defined porosity, often of molecular dimensions. Zeolites contain aluminum and silicon atoms in their framework and are the most extensively studied amongst all microporous materials. Framework structures with P, Ga, Fe, Co, Zn, B, Ti and a host of other elements have also been made. Typical synthesis of microporous materials involve mixing the framework elements (or compounds, thereof) in a basic solution, followed by aging in some cases and then heating at elevated temperatures. This process is termed hydrothermal synthesis, and involves complex chemical and physical changes. Because of a limited understanding of this process, most synthesis advancements happen by a trial and error approach. There is considerable interest in understanding the synthesis process at a molecular level with the expectation that eventually new framework structures will be built by design. The basic issues in the microporous materials crystallization process include: (1) Nature of the molecular units responsible for the crystal nuclei formation; (2) Nature of the nuclei and nucleation process; (3) Growth process of the nuclei into crystal; (4) Morphological control and size of the resulting crystal; (5) Surface structure of the resulting crystals; (6) Transformation of frameworks into other frameworks or condensed structures. The NASA-funded research described in this report focuses to varying degrees on all of the above issues and has been described in several publications. Following is the presentation of the highlights of our current research program. The report is divided into five sections: (1) Fundamental aspects of the crystal growth process; (2) Morphological and Surface properties of crystals; (3) Crystal dissolution and transformations; (4) Modeling of Crystal Growth; (5) Relevant Microgravity Experiments.

  7. Microporous calcium phosphate ceramics driving osteogenesis through surface architecture.

    PubMed

    Zhang, Jingwei; Barbieri, Davide; ten Hoopen, Hetty; de Bruijn, Joost D; van Blitterswijk, Clemens A; Yuan, Huipin

    2015-03-01

    The presence of micropores in calcium phosphate (CaP) ceramics has shown its important role in initiating inductive bone formation in ectopic sites. To investigate how microporous CaP ceramics trigger osteoinduction, we optimized two biphasic CaP ceramics (i.e., BCP-R and BCP-S) to have the same chemical composition, equivalent surface area per volume, comparable protein adsorption, similar ion (i.e., calcium and phosphate) exchange and the same surface mineralization potential, but different surface architecture. In particular, BCP-R had a surface roughness (Ra) of 325.4 ± 58.9 nm while for BCP-S it was 231.6 ± 35.7 nm. Ceramic blocks with crossing or noncrossing channels of 250, 500, 1000, and 2000 µm were implanted in paraspinal muscle of dogs for 12 weeks. The percentage of bone volume in the channels was not affected by the type of pores (i.e., crossing vs. closed) or their size, but it was greatly influenced by the ceramic type (i.e., BCP-R vs. BCP-S). Significantly, more bone was formed in the channels of BCP-R than in those of BCP-S. Since the two CaP ceramics differed only in their surface architecture, the results hereby demonstrate that microporous CaP ceramics may induce ectopic osteogenesis through surface architecture.

  8. On the physical adsorption of vapors by microporous carbons

    SciTech Connect

    Bradley, R.H. . Inst. of Surface Science and Technology); Rand, B. . Division of Ceramics)

    1995-01-01

    The physical adsorption of nonpolar and polar vapors by active carbons is discussed in relation to pore structure and pore wall chemistry. For nonpolar vapors the Dubinin-Radushkevich equation is used to derive micropore volumes (W[sub 0]), average adsorption energies (E[sub 0]), and micropore widths (L) for a number of systems. These parameters are used to interpret the adsorption behavior of nitrogen which, because it is a relatively small molecule, is frequently used at 77 K to probe porosity and surface area. Results are presented for three carbons from differing precursors, namely, coal, coconut shells, and polyvinylidene chloride (PVDC) to illustrate the applicability of the technique. For the latter carbon increases in micropore size, induced by activation in carbon dioxide, and reductions in accessible pore volume caused by heat treatment in argon are also characterized and related to structural changes. The approach is then extended to the adsorption of larger hydrogen vapors, where the resulting W[sub 0] values may require correction for molecular packing effects which occur in the lower relative pressure regions of the isotherms, i.e., during the filling of ultramicropores. These packing effects are shown to limit the use of the Polanyi characteristic curve for correlating isotherm data for several vapors, of differing molecular size, by one adsorbent. Data for the adsorption of water, which is a strongly polar liquid, have been interpreted using the Dubinin-Serpinsky equation.

  9. Simple and Stable Lipid Bilayer Formation: A Droplets Contacting Method using Parylene Micro-pores for Multiple Ion Channel Recordings

    NASA Astrophysics Data System (ADS)

    Tsuji, Yutaro; Kawano, Ryuji; Osaki, Toshihisa; Sasaki, Hirotaka; Miki, Norihisa; Takeuchi, Shoji

    This paper describes multiple ion-channel recordings through membrane proteins reconstituted in bilayer lipid membranes (BLMs) array. The BLMs array can be prepared by “Droplets Contacting Method” which forms BLMs at the interface of two lipid monolayers. Since this method does not require skilled techniques, it is highly reproducible and can be applied to automated system. We used a double well chip (DWC) for the droplets contacting method. We attempted to confine the BLMs forming areas with parylene micro-pore (parylene double well chip, PDWC) to augment the mechanical stability of BLMs. Subsequently, we arrayed the PDWC with electrodes for multiple recordings of channel proteins. We successfully demonstrated 14 channels simultaneous ion channel recordings through α-hemolysin.

  10. Hollow fiber gas-liquid membrane contactors for acid gas capture: a review.

    PubMed

    Mansourizadeh, A; Ismail, A F

    2009-11-15

    Membrane contactors using microporous membranes for acid gas removal have been extensively reviewed and discussed. The microporous membrane acts as a fixed interface between the gas and the liquid phase without dispersing one phase into another that offers a flexible modular and energy efficient device. The gas absorption process can offer a high selectivity and a high driving force for transport even at low concentrations. Using hollow fiber gas-liquid membrane contactors is a promising alternative to conventional gas absorption systems for acid gas capture from gas streams. Important aspects of membrane contactor as an efficient energy devise for acid gas removal including liquid absorbents, membrane characteristics, combination of membrane and absorbent, mass transfer, membrane modules, model development, advantages and disadvantages were critically discussed. In addition, current status and future potential in research and development of gas-liquid membrane contactors for acid gas removal were also briefly discussed.

  11. Temperature polarization coefficients in membrane distillation

    SciTech Connect

    Martinez-Diez, L.; Vazquez-Gonzalez, M.I.; Florido-Diaz, F.J.

    1998-04-01

    Membrane distillation is a membrane process in which two liquid phases at different temperatures are separated by a microporous hydrophobic membrane. The membrane plays the role of a physical support for the vapor-liquid interface. The aim of this paper is to study pure water transport by membrane distillation through a PTFE flat membrane. The dependence of the phenomenon on average temperature and recirculation rate at the membrane sides is investigated. The influence of these operating conditions on water transport is discussed by taking into account mass and heat transfer within the membrane and the adjoining liquid phases. The concept of temperature polarization is introduced into the transport equations and shown to be important in the interpretation of the experimental results.

  12. Thermodynamics and transport in microporous media. Progress report

    SciTech Connect

    Glandt, E.D.

    1992-09-01

    Focus of this report is on the thermodynamic properties/behavior of fluids contained or adsorbed on the random microporus materials (disordered solids). The Madden-Glandt formalism for fluids in disordered matrices is applied to realistic systems (gas adsorption in carbons, polymer partitioning). Work on microgeometry of solids and their percolation and connectedness properties was continued; a study of the simplest model for microporous materials (random-pore or ``Swiss cheese`` model) was completed. Work on irreversible adsorption was continued; a simple model for correlated adsorption was studied.

  13. Method for rapidly producing microporous and mesoporous materials

    DOEpatents

    Coronado, P.R.; Poco, J.F.; Hrubesh, L.W.; Hopper, R.W.

    1997-11-11

    An improved, rapid process is provided for making microporous and mesoporous materials, including aerogels and pre-ceramics. A gel or gel precursor is confined in a sealed vessel to prevent structural expansion of the gel during the heating process. This confinement allows the gelation and drying processes to be greatly accelerated, and significantly reduces the time required to produce a dried aerogel compared to conventional methods. Drying may be performed either by subcritical drying with a pressurized fluid to expel the liquid from the gel pores or by supercritical drying. The rates of heating and decompression are significantly higher than for conventional methods. 3 figs.

  14. Construction of nano- and microporous frameworks from octahedral bubble clusters.

    PubMed

    Woodley, S M; Watkins, M B; Sokol, A A; Shevlin, S A; Catlow, C R A

    2009-05-01

    We report a general method of constructing microporous, cubic frameworks from eight different high symmetry small clusters of ZnO, which were previously predicted via the application of an evolutionary algorithm. Using interatomic potentials, the lattice energies of the structures formed are computed. We analyse the relative stabilities within particular subsets of these periodic structures, and show that frameworks constructed from edge-sharing units of clusters with the T(h) point group are predicted to be much more stable than those with T(d). Our results have general implications for the nanostructures of systems whose bulk structures are based on tetrahedral coordination.

  15. Method for rapidly producing microporous and mesoporous materials

    DOEpatents

    Coronado, Paul R.; Poco, John F.; Hrubesh, Lawrence W.; Hopper, Robert W.

    1997-01-01

    An improved, rapid process is provided for making microporous and mesoporous materials, including aerogels and pre-ceramics. A gel or gel precursor is confined in a sealed vessel to prevent structural expansion of the gel during the heating process. This confinement allows the gelation and drying processes to be greatly accelerated, and significantly reduces the time required to produce a dried aerogel compared to conventional methods. Drying may be performed either by subcritical drying with a pressurized fluid to expel the liquid from the gel pores or by supercritical drying. The rates of heating and decompression are significantly higher than for conventional methods.

  16. The role of UHMW-PE in microporous PE separators

    SciTech Connect

    Wang, L.C.; Harvey, M.K.; Stein, H.L.; Scheunemann, U.

    1997-12-01

    Microporous PE separators have gained large popularity in the lead acid battery industry, particularly in SLI (Starting, Lighting and Ignition) Automotive Applications. The PE (Polyethylene) in battery separator is actually UHMW-PE (Ultra High Molecular Weight Polyethylene). UHMW-PE has a molecular weight more than ten times that of conventional HDPE (High Density Polyethylene). This paper gives an overview of the UHMW-PE`s contributions to the PE battery separator process, assembly, and performance, in comparison to other conventional separators, such as PVC (Polyvinyl Chloride), cellulose, and glass fiber.

  17. Pentavalent outer membrane vesicles of Vibrio cholerae induce adaptive immune response and protective efficacy in both adult and passive suckling mice models.

    PubMed

    Sinha, Ritam; Koley, Hemanta; Nag, Dhrubajyoti; Mitra, Soma; Mukhopadhyay, Asish K; Chattopadhyay, Brajadulal

    2015-03-01

    Recently, we demonstrated oral immunizations with single serotype outer membrane vesicles of Vibrio cholerae induced serogroup specific protective immunity in the RITARD model. In our present study, we advanced our research by formulating multi-serotype outer membrane vesicles, mixing the OMVs of five virulent V. cholerae strains. Four doses of oral immunization with cholera pentavalent outer membrane vesicles (CPMVs) induced V. cholerae specific B and T cell responses. CPMVs-immunized mice generated long lasting serum IgG, IgA, IgM as well as mucosal sIgA and also elicited a higher percentage of CD4+ T cell distribution in spleen. Our study revealed that in vitro CPMVs-activated dendritic cells were secreting T cell polarizing cytokines, IL-12p40, IL-4, IL-6 and IL-1β. Moreover, purified splenic CD4+ T cells of immunized mice also secreted IL-4, IL-13 and IL-17 cytokines, indicating the initiation of Th2 and Th17 cell mediated immune responses. CPMVs immunized adult female mice and their offspring were significantly protected from heterologous challenge with wild type V. cholerae. CPMVs could be exploited for the development of a novel non-living vaccine against circulating cholera in near future.

  18. Facile preparation and ultra-microporous structure of melamine-resorcinol-formaldehyde polymeric microspheres.

    PubMed

    Zhou, Huanhuan; Xu, Sheng; Su, Haiping; Wang, Mei; Qiao, Wenming; Ling, Licheng; Long, Donghui

    2013-05-01

    A facile hydrothermal method was developed to synthesize nitrogen-rich phenolic microspheres with a tunable ultra-microporous structure for CO(2) adsorption. The results highlighted that chemical composition and ultramicroporous size, much more than surface area, dictated the CO(2) uptake in a microporous organic polymer.

  19. The formation of an ordered microporous aluminum-based material mediated by phthalic acid.

    PubMed

    Zhang, Wei; Cai, Jian-Hua; Huang, Pei-Pei; Hu, Lin-Lin; Cao, An-Min; Wan, Li-Jun

    2016-06-28

    By using phthalic acid as a soft template, we showed that it was possible to prepare a microporous aluminum-based material when the precipitation of Al(3+) was properly controlled. We also identified that this microporous aluminum-based material could be promising for the removal of fluoride ions in water treatment. PMID:27263661

  20. Observation of microporous cesium salts of 12-tungstosilicic acid using scanning transmission electron microscopy.

    PubMed

    Hiyoshi, Norihito; Kamiya, Yuichi

    2015-06-21

    Heteropolyanions and their arrays in microporous cesium salts of 12-tungstosilicic acid, Cs2.5H1.5[SiW12O40] and Cs4.0[SiW12O40], were observed by aberration-corrected scanning transmission electron microscopy. Microstructures that form micropores in the polyoxometalates were visualized.

  1. Microporous carbon derived from polyaniline base as anode material for lithium ion secondary battery

    SciTech Connect

    Xiang, Xiaoxia; Liu, Enhui; Huang, Zhengzheng; Shen, Haijie; Tian, Yingying; Xiao, Chengyi; Yang, Jingjing; Mao, Zhaohui

    2011-08-15

    Highlights: {yields} Nitrogen-containing microporous carbon was prepared from polyaniline base by K{sub 2}CO{sub 3} activation, and used as anode material for lithium ion secondary battery. {yields} K{sub 2}CO{sub 3} activation promotes the formation of amorphous and microporous structure. {yields} High nitrogen content, and large surface area with micropores lead to strong intercalation between carbon and lithium ion, and thus improve the lithium storage capacity. -- Abstract: Microporous carbon with large surface area was prepared from polyaniline base using K{sub 2}CO{sub 3} as an activating agent. The physicochemical properties of the carbon were characterized by scanning electron microscope, X-ray diffraction, Brunauer-Emmett-Teller, elemental analyses and X-ray photoelectron spectroscopy measurement. The electrochemical properties of the microporous carbon as anode material in lithium ion secondary battery were evaluated. The first discharge capacity of the microporous carbon was 1108 mAh g{sup -1}, whose first charge capacity was 624 mAh g{sup -1}, with a coulombic efficiency of 56.3%. After 20 cycling tests, the microporous carbon retains a reversible capacity of 603 mAh g{sup -1} at a current density of 100 mA g{sup -1}. These results clearly demonstrated the potential role of microporous carbon as anode for high capacity lithium ion secondary battery.

  2. Impact of mineral micropores on transport and fate of organic contaminants: a review.

    PubMed

    Cheng, Hefa; Hu, Erdan; Hu, Yuanan

    2012-03-15

    Nanometer-scale pores are abundant in porous geological media (soils, sediments, and aquifer materials), and may account for over >90% of total mineral surface areas. Sorption of organic contaminants in mineral micropores (<2 nm) plays a key role in controlling their fate and transport when the porous geological media have very low organic carbon contents (<0.1%). Significant adsorption of hydrophobic organic contaminants could only occur in the hydrophobic micropore spaces because of the strong competition from water. The rate of desorption from micropores is very slow due to hindered diffusion, resulting in distinct two-stage desorption behavior for microporous solids. Size exclusion effect prevents micropore-sorbed contaminants from being accessed by microorganisms and their extracellular enzymes, thus reducing their bioavailability and biodegradation rates. Results from recent studies indicate that sorption in micropores can also inhibit abiotic degradation of reactive contaminants by protecting them in confined spaces with little reactive water, slowing down hydrolysis and other water-mediated transformations. As a result of the inhibitory effect on abiotic and biotic transformations, and the slow desorption due to hindered diffusion, sorption in hydrophobic micropores of porous geological media can cause preservation of anthropogenic organic contaminants in the subsurface and may increase their persistence to the time scale of geological ages under appropriate conditions. From a practical perspective, understanding the role of mineral micropores is important in assessing the long-term ecotoxicological risk of organic contaminants in the subsurface and designing remediation strategies.

  3. Improved bioresorbable microporous intravascular stents for gene therapy.

    PubMed

    Ye, Y W; Landau, C; Meidell, R S; Willard, J E; Moskowitz, A; Aziz, S; Carlisle, E; Nelson, K; Eberhart, R C

    1996-01-01

    Drug imbibing microporous stents are under development at a number of centers to enhance healing of the arterial wall after balloon coronary angioplasty procedures. The authors improved the mechanical strength and reservoir properties of a biodegradable microporous stent reported to this Society in 1994. A combined tubular/helical coil stent is readily fabricated by flotation/precipitation and casting/ winding techniques. A two stage solvent swelling technique allows precise adjustment of the surface hydrophilic/hydrophobic balance. These developments permit seven-fold improvement in drug capacity without significantly altering mechanical properties. Stents modified in this manner retain tensile and compressive strength and are suitable for remote deployment. Elution kinetics of these modified stents suggest they are suitable for gene delivery. Successful gene transfer and transmural expression have been demonstrated after implantation of stents impregnated with a recombinant adenovirus carrying a nuclear localizing beta-galactosidase reporter gene into rabbit carotid arteries. These studies suggest that surface modified, bioresorbable polymer stents ultimately may be useful adjunctive devices for gene transfer during percutaneous transluminal revascularization.

  4. Highly Monodisperse Microporous Polymeric and Carbonaceous Nanospheres with Multifunctional Properties

    PubMed Central

    Ouyang, Yi; Shi, Huimin; Fu, Ruowen; Wu, Dingcai

    2013-01-01

    Fabrication of monodisperse porous polymeric nanospheres with diameters below 500 nm remains a great challenge, due to serious crosslinking between neighboring nanospheres during pore-making process. Here we show how a versatile hypercrosslinking strategy can be used to prepare monodisperse microporous polystyrene nanospheres (MMPNSs) with diameters as low as ca. 190 nm. In our approach, an unreactive crosslinked PS outer skin as protective layer can be in-situ formed at the very beginning of hypercrosslinking treatment to minimize the undesired inter-sphere crosslinking. The as-prepared MMPNSs with a well-developed microporous network demonstrate unusual multifunctional properties, including remarkable colloidal stability in aqueous solution, good adsorption-release property for drug, and large adsorption capacity toward organic vapors. Surprisingly, MMPNSs can be directly transformed into high-surface-area monodisperse carbon nanospheres with good colloidal stability via a facile hydrothermal-assisted carbonization procedure. These findings provide a new benchmark for fabricating well-defined porous nanospheres with great promise for various applications. PMID:23478487

  5. Interpenetrating polymer network ion exchange membranes and method for preparing same

    DOEpatents

    Alexandratos, Spiro D.; Danesi, Pier R.; Horwitz, E. Philip

    1989-01-01

    Interpenetrating polymer network ion exchange membranes include a microporous polymeric support film interpenetrated by an ion exchange polymer and are produced by absorbing and polymerizing monomers within the support film. The ion exchange polymer provides ion exchange ligands at the surface of and throughout the support film which have sufficient ligand mobility to extract and transport ions across the membrane.

  6. Recovery of ammonia from poultry litter using flat gas permeable membranes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of flat gas-permeable membranes was investigated as components of a new process to capture and recover ammonia (NH3) in poultry houses. This process includes the passage of gaseous NH3 through a microporous hydrophobic membrane, capture with a circulating dilute acid on the other side of the...

  7. Effect of phase inversion on microporous structure development of Al 2O 3/poly(vinylidene fluoride-hexafluoropropylene)-based ceramic composite separators for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Jeong, Hyun-Seok; Kim, Dong-Won; Jeong, Yeon Uk; Lee, Sang-Young

    To improve the thermal shrinkage of the separators that are essential to securing the electrical isolation between electrodes in lithium-ion batteries, we develop a new separator based on a ceramic composite membrane. Introduction of microporous, ceramic coating layers onto both sides of a polyethylene (PE) separator allows such a progress. The ceramic coating layers consist of nano-sized alumina (Al 2O 3) powders and polymeric binders (PVdF-HFP). The microporous structure of the ceramic coating layers is observed to be crucial to governing the thermal shrinkage as well as the ionic transport of the ceramic composite separators. This microporous structure is determined by controlling the phase inversion, more specifically, nonsolvent (water) contents in the coating solutions. To provide a theoretical basis for this approach, a pre-investigation on the phase diagram for a ternary mixture comprising PVdF-HFP, acetone, and water is conducted. On the basis of this observation, the effect of phase inversion on the morphology and air permeability (i.e. Gurley value) of ceramic coating layers is systematically discussed. In addition, to explore the application of ceramic composite separators to lithium-ion batteries, the influence of the structural change in the coating layers on the thermal shrinkage and electrochemical performance of the separators is quantitatively identified.

  8. Porous membrane utilization in plant nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Hinkle, C. R.; Prince, R. P.; Knott, W. M., III

    1987-01-01

    A spacecraft hydroponic plant growth unit of tubular configuration, employing a microporous membrane as a capilary interface between plant roots and a nutrient solution, is presented. All three of the experimental trials undertaken successfully grew wheat from seed to harvest. Attention is given to the mass/seed, number of seeds/head, ratio of seed dry mass to total plant dry mass, production of tillers, and mass of seed/plant. Dry matter production is found to be reduced with increasing suction pressure; this is true for both average seed and average total dry matter/plant. This may be due to a reduction in water and nutrient availability through the microporous membrane.

  9. A plasma membrane protein is involved in cell contact-mediated regulation of tissue-specific genes in adult hepatocytes

    PubMed Central

    1991-01-01

    We have identified the liver-regulating protein (LRP), a cell surface protein involved in the maintenance of hepatocyte differentiation when cocultured with rat liver epithelial cells (RLEC). LRP was defined by immunoreactivity to a monoclonal antibody (mAb L8) prepared from RLEC. mAb L8 specifically detected two polypeptides of 85 and 73 kD in immunoprecipitation of both hepatocyte- and RLEC-iodinated plasma membranes. The involvement of these polypeptides, which are integral membrane proteins, in cell interaction-mediated regulation of hepatocytes was assessed by evaluating the perturbing effects of the antibody on cocultures with RLEC. Several parameters characteristic of differentiated hepatocytes were studied, such as liver-specific and house-keeping gene expression, cytoskeletal organization and deposition of extracellular matrix (ECM). An early cytoskeletal disturbance was evidenced and a marked alteration of hepatocyte functional capacity was observed in the presence of the antibody, together with a loss of ECM deposition. By contrast, cell-cell aggregation or cell adhesion to various extracellular matrix components were not affected. These findings suggest that LRP is distinct from an extracellular matrix receptor. The fact that early addition of mAb L8 during cell contact establishment was necessary to be effective may indicate that LRP is a novel plasma membrane protein that plays an early pivotal role in the coordinated metabolic changes which lead to the differentiated phenotype of mature hepatocytes. PMID:1918151

  10. A Case of Scrub Typhus Complicated by Adult Respiratory Distress Syndrome and Successful Management with Extracorporeal Membrane Oxygenation.

    PubMed

    Choi, Woo Young; Lee, Seung Yun; Kwon, Hea Yoon; Im, Jae Hyoung; Durey, Areum; Baek, Ji Hyeon; Kim, Young Sam; Kang, Jae-Seung; Lee, Jin-Soo

    2016-09-01

    A 67-year-old woman was diagnosed as having scrub typhus with pneumonitis. On admission, she was started on a combination therapy with levofloxacin and doxycycline. However, the patient developed severe acute respiratory distress syndrome (ARDS) on the 2nd day, and as a result, she underwent extracorporeal membrane oxygenation (ECMO). She was weaned from ECMO on the 10th day, as her respiratory status gradually improved. She was discharged without sequelae on the 23rd day. The outcome suggests that the use of ECMO should be considered for patients with ARDS induced from scrub typhus. PMID:27458040

  11. Suppression of secondary electron yield by micro-porous array structure

    NASA Astrophysics Data System (ADS)

    Ye, M.; He, Y. N.; Hu, S. G.; Wang, R.; Hu, T. C.; Yang, J.; Cui, W. Z.

    2013-02-01

    We study secondary electron yield (SEY) suppression for metal materials using a roughened surface with a micro-porous array. First, we perform a Monte Carlo simulation of the electron trajectory in a single cylindrical well using a phenomenological model of secondary electron emission and the SEY suppression efficiency of a micro-porous array. The simulation results show that the SEY of a roughened surface is affected significantly by the aspect ratio of the micro-pores and the surface porosity of the metal plate. Then, to verify the simulation results, we produce a micro-porous array on metal plates using photolithography and measure their SEYs. We show that the micro-porous array structure can efficiently suppress the SEY of metal materials, and the measurements agree quantitatively with the corresponding simulation results. Finally, we derive an analytical formula to evaluate easily the SEY suppression efficiency of the Ag micro-porous array. In total, the micro-porous array proposed in this paper offers an alternative to SEY suppression in related areas such as multipactor effects in satellite payloads or electron cloud effects in accelerators.

  12. Suppression of secondary electron yield by micro-porous array structure

    SciTech Connect

    Ye, M.; He, Y. N.; Hu, S. G.; Wang, R.; Hu, T. C.; Yang, J.; Cui, W. Z.

    2013-02-21

    We study secondary electron yield (SEY) suppression for metal materials using a roughened surface with a micro-porous array. First, we perform a Monte Carlo simulation of the electron trajectory in a single cylindrical well using a phenomenological model of secondary electron emission and the SEY suppression efficiency of a micro-porous array. The simulation results show that the SEY of a roughened surface is affected significantly by the aspect ratio of the micro-pores and the surface porosity of the metal plate. Then, to verify the simulation results, we produce a micro-porous array on metal plates using photolithography and measure their SEYs. We show that the micro-porous array structure can efficiently suppress the SEY of metal materials, and the measurements agree quantitatively with the corresponding simulation results. Finally, we derive an analytical formula to evaluate easily the SEY suppression efficiency of the Ag micro-porous array. In total, the micro-porous array proposed in this paper offers an alternative to SEY suppression in related areas such as multipactor effects in satellite payloads or electron cloud effects in accelerators.

  13. Synthetic Zeolites and Other Microporous Oxide Molecular Sieves

    NASA Astrophysics Data System (ADS)

    Sherman, John D.

    1999-03-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

  14. A three-dimensional microporous coordination polymer with fluorescent property

    NASA Astrophysics Data System (ADS)

    Gao, Chaoying; Liu, Shuxia; Xie, Linhua; Ren, Yuanhang; Cao, Ruige; Cao, Jianfang; Zhao, Xinyu

    2008-11-01

    A microporous metal-organic coordination polymer formulated as [Cd 2(btec)(H 2O) 2]·0.8DMF (1), where btec = 1,2,4,5-benzenetetracarboxylate and DMF = N, N-dimethylformamide, has been isolated under solvothermal condition and characterized by elemental analyses, IR, thermal stability analysis, fluorescent spectrum, and single-crystal X-ray diffraction analysis. The framework in 1 possesses a three-dimensional architecture with ordered one-dimensional rhombus channels, the dimensions of channels are approximately 10 Å at the widest and 3 Å at the narrowest spacing considering the van der Waal radii of atoms in the framework running along the a-axis. Furthermore, compound 1 shows intense photoluminescent property at room temperature.

  15. Wear and Friction Behavior of Metal Impregnated Microporous Carbon Composites

    NASA Technical Reports Server (NTRS)

    Goller, Gultekin; Koty, D. P.; Tewari, S. N.; Singh, M.; Tekin, A.

    1996-01-01

    Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the composites is very sensitive to the size and distribution of the microstructural constituents.

  16. Reactive Infiltration of Silicon Melt Through Microporous Amorphous Carbon Preforms

    NASA Technical Reports Server (NTRS)

    Sangsuwan, P.; Tewari, S. N.; Gatica, J. E.; Singh, M.; Dickerson, R.

    1999-01-01

    The kinetics of unidirectional capillary infiltration of silicon melt into microporous carbon preforms have been investigated as a function of the pore morphology and melt temperature. The infiltrated specimens showed alternating bands of dark and bright regions, which corresponded to the unreacted free carbon and free silicon regions, respectively. The decrease in the infiltration front velocity for increasing infiltration distances, is in qualitative agreement with the closed-form solution of capillarity driven fluid flow through constant cross section cylindrical pores. However, drastic changes in the thermal response and infiltration front morphologies were observed for minute differences in the preforms microstructure. This suggests the need for a dynamic percolation model that would account for the exothermic nature of the silicon-carbon chemical reaction and the associated pore closing phenomenon.

  17. Synthetic zeolites and other microporous oxide molecular sieves.

    PubMed

    Sherman, J D

    1999-03-30

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

  18. Nanoscale encapsulation: the structure of cations in hydrophobic microporous aluminosilicates

    SciTech Connect

    Wasserman, S.R.; Yuchs, S.E.; Giaquinta, D.; Soderholm, L.; Song, Kang

    1996-10-01

    Hydrophobic microporous aluminosilicates, created by organic surface modification of inherently hydrophilic materials such as zeolites and clays, are currently being investigated as storage media for hazardous cations. Use of organic monolayers to modify the surface of an aluminosilicate after introducing an ion into the zeolite/clay reduces the interaction of water with the material. Resulting systems are about 20 times more resistant to leaching of stored ion. XAS spectra from the encapsulated ion demonstrate that byproducts from the organic modifier can complex with the stored cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and speciation of the encapsulated ion may change upon application of the hydrophobic layer.

  19. Controlled release of chlorhexidine from amorphous microporous silica.

    PubMed

    Verraedt, E; Pendela, M; Adams, E; Hoogmartens, J; Martens, J A

    2010-02-25

    A new system for the controlled release of the antiseptic chlorhexidine is presented. Amorphous microporous silica (AMS) excipient material was synthesized via an acid catalyzed sol-gel method and shaped as powder or coating. Chlorhexidine diacetate was introduced into the pores of the AMS silica via the incipient wetness impregnation method. This silica reservoir maintained a slow release of chlorhexidine over more than 7days. Chlorhexidine release was controlled by configurational diffusion in the AMS pores having free diameters of less than 1nm. The release of chlorhexidine was fine tuned by adapting particle size and pore diameter. Controlled release of chlorhexidine from an AMS coating on silicon wafer was demonstrated. PMID:19804804

  20. Effects of supplemental long-chain omega-3 fatty acids and erythrocyte membrane fatty acid content on circulating inflammatory markers in a randomized controlled trial of healthy adults.

    PubMed

    Flock, Michael R; Skulas-Ray, Ann C; Harris, William S; Gaugler, Trent L; Fleming, Jennifer A; Kris-Etherton, Penny M

    2014-10-01

    The long-chain omega-3 polyunsaturated (n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), may have anti-inflammatory effects. We evaluated the dose-response effect of EPA+DHA supplementation on circulating TNF-α, IL-6, and CRP and explored associations between red blood cell (RBC) membrane PUFA content and TNF-α, IL-6, and CRP. Young adults with low fish intake (n=116) received one of five doses (0, 300, 600, 900, or 1,800 mg/d EPA+DHA) for 5 months. There were no significant effects of supplemental EPA+DHA on IL-6 or CRP; however, there was a marginal treatment effect for TNF-α (p<0.08). At baseline, higher quartiles of RBC DHA were associated with lower TNF-α (p=0.001); higher quartiles of arachidonic acid were associated with higher TNF-α (p=0.005). EPA+DHA supplementation had no dose-response effect on TNF-α, IL-6, or CRP in healthy young adults; however, associations between inflammatory markers and RBC PUFA warrant further investigation.

  1. Lignin-based microporous materials as selective adsorbents for carbon dioxide separation.

    PubMed

    Meng, Qing Bo; Weber, Jens

    2014-12-01

    Suitable solid adsorbents are demanded for carbon capture and storage (CCS) processes. In this work, a novel microporous polymer is developed by hypercrosslinking of organosolv lignin, which is a renewable resource. Reaction with formaldehyde dimethyl acetal (FDA) via Friedel-Crafts reaction gives microporous networks, with moderate capacity of carbon dioxide but excellent selectivity towards CO2 /N2 mixture as predicted on the basis of ideal adsorption-solution theory (IAST). Pyrolysis of pure organosolv lignin results in microporous carbon powders, while pyrolysis of hypercrosslinked organosolv lignin yields shape-persistent materials with increased CO2 capacity while maintaining very good selectivity.

  2. Output characteristics of a laser utilizing rhodamine 6G in microporous glass

    SciTech Connect

    Al'tshuler, G.B.; Dul'neva, E.G.; Krylov, K.I.; Meshkovskii, I.K.; Urbanovich, V.S.

    1983-06-01

    A study was made of the lasing characteristics of new active media in the form of microporous glass containing a dye. The efficiency of conversion of the pump radiation, and the spatial and frequency spectra of the output radiation were determined for lasers with dispersive and nondispersive resonators and with active elements in the form of an ethanol solution of rhodamine 6G or microporous glass containing either rhodamine 6G or its ethanol solution. It was found that the use of active elements made of microporous glass and containing rhodamine 6G improved considerably the spatial characteristics of the output radiation compared with those obtained using liquid active media.

  3. The economic effect of extracorporeal membrane oxygenation to support adults with severe respiratory failure in Brazil: a hypothetical analysis

    PubMed Central

    Park, Marcelo; Mendes, Pedro Vitale; Zampieri, Fernando Godinho; Azevedo, Luciano Cesar Pontes; Costa, Eduardo Leite Vieira; Antoniali, Fernando; Ribeiro, Gustavo Calado de Aguiar; Caneo, Luiz Fernando; da Cruz Neto, Luiz Monteiro; Carvalho, Carlos Roberto Ribeiro; Trindade, Evelinda Marramon

    2014-01-01

    Objective To analyze the cost-utility of using extracorporeal oxygenation for patients with severe acute respiratory distress syndrome in Brazil. Methods A decision tree was constructed using databases from previously published studies. Costs were taken from the average price paid by the Brazilian Unified Health System (Sistema Único de Saúde; SUS) over three months in 2011. Using the data of 10,000,000 simulated patients with predetermined outcomes and costs, an analysis was performed of the ratio between cost increase and years of life gained, adjusted for quality (cost-utility), with survival rates of 40 and 60% for patients using extracorporeal membrane oxygenation. Results The decision tree resulted in 16 outcomes with different life support techniques. With survival rates of 40 and 60%, respectively, the increased costs were R$=-301.00/-14.00, with a cost of R$=-30,913.00/-1,752.00 paid per six-month quality-adjusted life-year gained and R$=-2,386.00/-90.00 per quality-adjusted life-year gained until the end of life, when all patients with severe ARDS were analyzed. Analyzing only patients with severe hypoxemia (i.e., a ratio of partial oxygen pressure in the blood to the fraction of inspired oxygen <100mmHg), the increased cost was R$=-5,714.00/272.00, with a cost per six-month quality-adjusted life-year gained of R$=-9,521.00/293.00 and a cost of R$=-280.00/7.00 per quality-adjusted life-year gained. Conclusion The cost-utility ratio associated with the use of extracorporeal membrane oxygenation in Brazil is potentially acceptable according to this hypothetical study. PMID:25295819

  4. SiO2/polyacrylonitrile membranes via centrifugal spinning as a separator for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Yanilmaz, Meltem; Lu, Yao; Li, Ying; Zhang, Xiangwu

    2015-01-01

    Centrifugal spinning is a fast, cost-effective and safe alternative to the electrospinning technique, which is commonly used for making fiber-based separator membranes. In this work, SiO2/polyacrylonitrile (PAN) membranes were produced by using centrifugal spinning and they were characterized by using different electrochemical techniques for use as separators in Li-ion batteries. SiO2/PAN membranes exhibited good wettability and high ionic conductivity due to their highly porous fibrous structure. Compared with commercial microporous polyolefin membranes, SiO2/PAN membranes had larger liquid electrolyte uptake, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. SiO2/PAN membrane separators were assembled into lithium/lithium iron phosphate cells and these cells delivered high capacities and exhibited good cycling performance at room temperature. In addition, cells using SiO2/PAN membranes showed superior C-rate performance compared to those using microporous PP membrane.

  5. Template-mediated Synthesis of Hollow Microporous Organic Nanorods with Tunable Aspect Ratio

    PubMed Central

    Li, Qingyin; Jin, Shangbin; Tan, Bien

    2016-01-01

    Hollow microporous organic nanorods (HMORs) with hypercrosslinked polymer (HCPs) shells were synthesized through emulsion polymerization followed by hypercrosslinking. The HMORs have tunable aspect ratios, high BET surface areas and monodispersed morphologies, showing good performance in gas adsorpion. PMID:27506370

  6. Effect of pH and zinc stress on micropore system of rye roots

    NASA Astrophysics Data System (ADS)

    Szatanik-Kloc, A.

    2012-07-01

    After zinc stress the total micropore volume decreased remarkably while the average micropore radius increased remarkably for the rye roots. Pore size distribution functions of the roots after the additional zinc application showed the decrease of the small micropore fraction from ca 2 to 10 nm and the increase of the large micropore from ca 22 to 50 nm. The root surface pores were fractal. After the stress pore fractal dimension increased. The changes of the microporosity observed in the roots surface can be related to the high content of zinc in the cell wall and/or due to the shortage of Ca+2 the intercellular spaces particularly in the tissues of seminal cortex of the studied roots might have grown.

  7. Template-mediated Synthesis of Hollow Microporous Organic Nanorods with Tunable Aspect Ratio

    NASA Astrophysics Data System (ADS)

    Li, Qingyin; Jin, Shangbin; Tan, Bien

    2016-08-01

    Hollow microporous organic nanorods (HMORs) with hypercrosslinked polymer (HCPs) shells were synthesized through emulsion polymerization followed by hypercrosslinking. The HMORs have tunable aspect ratios, high BET surface areas and monodispersed morphologies, showing good performance in gas adsorpion.

  8. Template-mediated Synthesis of Hollow Microporous Organic Nanorods with Tunable Aspect Ratio.

    PubMed

    Li, Qingyin; Jin, Shangbin; Tan, Bien

    2016-08-10

    Hollow microporous organic nanorods (HMORs) with hypercrosslinked polymer (HCPs) shells were synthesized through emulsion polymerization followed by hypercrosslinking. The HMORs have tunable aspect ratios, high BET surface areas and monodispersed morphologies, showing good performance in gas adsorpion.

  9. Characterization of the micropore structure of activated carbons by adsorptions of nitrogen and some hydrocarbons

    SciTech Connect

    Guezel, F.

    1999-02-01

    In the present study the effects of the duration of carbonization and physical activation properties of activated carbon from vegetable materials were investigated. Peanut shells were used to obtain active carbon. These shells were activated chemically with ZnCl{sub 2} and/or CO{sub 2} for different times, and the micropore structures of these active carbons were studied by measuring the adsorption isotherms for nitrogen and some hydrocarbons such as benzene, n-butane, isobutane, 2,2-dimethylbutane, and isooctane. As the physical activation time was increased, the primary micropores, which were measured at 0.01 relative pressure, were reduced, and they were replaced by larger secondary and tertiary micropores which were measured at 0.15--0.01 and 0.30--0.15 relative pressures. The ratios of the mesopore volume to the micropore volume also increased as the duration of physical activation increased.

  10. Citrate impairs the micropore diffusion of phosphate into pure and C-coated goethite

    NASA Astrophysics Data System (ADS)

    Mikutta, Christian; Lang, Friederike; Kaupenjohann, Martin

    2006-02-01

    Anions of polycarboxylic low-molecular-weight organic acids (LMWOA) compete with phosphate for sorption sites of hydrous Fe and Al oxides. To test whether the sorption of LMWOA anions decreases the accessibility of micropores (<2 nm) of goethite (α-FeOOH) for phosphate, we studied the kinetics of citrate-induced changes in microporosity and the phosphate sorption kinetics of synthetic goethite in the presence and absence of citrate in batch systems for 3 weeks (500 μM of each ion, pH 5). We also used C-coated goethite obtained after sorption of dissolved organic matter in order to simulate organic coatings in the soil. We analyzed our samples with N 2 adsorption and electrophoretic mobility measurements. Citrate clogged the micropores of both adsorbents by up to 13% within 1 h of contact. The micropore volume decreased with increasing concentration and residence time of citrate. In the absence of citrate, phosphate diffused into micropores of the pure and C-coated goethite. The C coating (5.6 μmol C m -2) did not impair the intraparticle diffusion of phosphate. In the presence of citrate, the diffusion of phosphate into the micropores of both adsorbents was strongly impaired. We attribute this to the micropore clogging and the ligand-induced dissolution of goethite by citrate. While the diffusion limitation of phosphate by citrate was stronger when citrate was added before phosphate to pure goethite, the order of addition of both ions to C-coated goethite had only a minor effect on the intraparticle diffusion of phosphate. Micropore clogging and dissolution of microporous hydrous Fe and Al oxides may be regarded as potential strategies of plants to cope with phosphate deficiency in addition to ligand-exchange.

  11. Hypercrosslinked aromatic heterocyclic microporous polymers: a new class of highly selective CO2 capturing materials.

    PubMed

    Luo, Yali; Li, Buyi; Wang, Wei; Wu, Kangbing; Tan, Bien

    2012-11-01

    Aromatic heterocyclic microporous polymers with high surface areas are obtained by directly crosslinking of the heterocyclic monomers under mild conditions. Owing to the narrow pore system and the heteroatom-rich pore surface, these networks exhibit high CO(2) adsorption capacity and selectivity. At 273 K, the CO(2)/N(2) selectivity of Py-1 is about 117, which is among the highest the reported microporous materials.

  12. Metal oxide membranes for gas separation

    DOEpatents

    Anderson, M.A.; Webster, E.T.; Xu, Q.

    1994-08-30

    A method for formation of a microporous ceramic membrane onto a porous support includes placing a colloidal suspension of metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane having mean pore sizes less than 30 Angstroms and useful for ultrafiltration, reverse osmosis, or gas separation. 4 figs.

  13. Metal oxide membranes for gas separation

    DOEpatents

    Anderson, Marc A.; Webster, Elizabeth T.; Xu, Qunyin

    1994-01-01

    A method for permformation of a microporous ceramic membrane onto a porous support includes placing a colloidal suspension of metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane having mean pore sizes less than 30 Angstroms and useful for ultrafiltration, reverse osmosis, or gas separation.

  14. SANS Investigations of CO2 Adsorption in Microporous Carbon

    SciTech Connect

    Bahadur, Jitendra; Melnichenko, Yuri B.; He, Lilin; Contescu, Cristian I.; Gallego, Nidia C.; Carmichael, Justin R.

    2015-08-07

    The high pressure adsorption behavior of CO2 at T = 296 K in microporous carbon was investigated by small-angle neutron scattering (SANS) technique. A strong densification of CO2 in micropores accompanied by non-monotonic adsorption-induced pore deformation was observed. The density of confined CO2 increases rapidly with pressure and reaches the liquid –like density at 20 bar, which corresponds to the relative pressure of P/Psat ~0.3. At P > 20 bar density of confined CO2 increases slowly approaching a plateau at higher pressure. The size of micropores first increases with pressure, reaches a maximum at 20 bar, and then decreases with pressure. A complementary SANS experiment conducted on the same microporous carbon saturated with neutron-transparent and non-adsorbing inert gas argon shows no deformation of micropores at pressures up to ~200 bars. This result demonstrates that the observed deformation of micropores in CO2 is an adsorption-induced phenomenon, caused by the solvation pressure - induced strain and strong densification of confined CO2 .

  15. Investigation on the antibacterial micro-porous titanium with silver nano-particles.

    PubMed

    Dong, Wei; Zhu, Yingchun; Zhang, Jingxian; Lu, Liqiang; Zhao, Chengjian; Qin, Lifeng; Li, Yingbin

    2013-10-01

    Micro-porous titanium is coated with silver nanoparticles by using a simple chemical reduction method that exhibits excellent antibacterial ability. Scanning electron microscopy (SEM) shows that the silver nanoparticles with average sizes of about 100 nm are formed homogeneously on the micro-porous titanium surface. After the micro-porous Ti coated with silver nano particles is treated by heating, the average size of the silver nano particles is slightly increased, but the nano particles are more uniformly dispersed on the surface of the micro-porous titanium. X-ray diffraction (XRD) indicates that those nanoparticles are metallic silver produced on the micro-porous titanium surface. The samples of micro-porous titanium coated with silver nanoparticles inhibit the growth of Escherichia coli. Our results show that the electrical double layer of the samples play an important role in the antibiosis and this study opens a new window for antibacterial mechanism which may be suitable for the other antibacterial metallic materials.

  16. Microporous Co@CoO nanoparticles with superior microwave absorption properties.

    PubMed

    Liu, Tong; Pang, Yu; Zhu, Mu; Kobayashi, Satoru

    2014-02-21

    Nanoporous metal materials with many potential applications have been synthesized by a chemical dealloying approach. The fabrication of nanoporous metal nanoparticles (NPs), however, is still challenging due to the difficulties in producing suitable nanoscale precursors. Herein, nanoporous Co NPs of 31 nm have been successfully prepared by dealloying Co-Al NPs, and surprisingly they possess micropores in a range from 0.7 to 1.7 nm and a large surface area of 50 m(2) g(-1). The crystalline size of the microporous NPs is 2-5 nm. Through the passivation process, the microporous Co NPs covered with CoO (Co@CoO) are generated as a result of the surface oxidation of Co. They exhibit better microwave absorption properties than their nonporous counterpart. An enhanced reflection loss (RL) value of -90.2 dB is obtained for the microporous Co@CoO NPs with a thickness of merely 1.3 mm. The absorption bandwidth corresponding to the RL below -10 dB reaches 7.2 GHz. The microwave absorption mechanism is discussed in terms of micropore morphology, core@shell structure and nanostructure. This novel microporous material may open new routes for designing high performance microwave absorbers.

  17. Asymmetric hydration structure around calcium ion restricted in micropores fabricated in activated carbons.

    PubMed

    Ohkubo, Takahiro; Kusudo, Tomoko; Kuroda, Yasushige

    2016-11-23

    The adsorbed phase and hydration structure of an aqueous solution of Ca(NO3)2 restricted in micropores fabricated in activated carbons (ACs) having different average pore widths (0.63 and 1.1 nm) were investigated with the analysis of adsorption isotherms and x-ray absorption fine structure (XAFS) spectra on Ca K-edge. The adsorbed density of Ca(2+) per unit micropore volume in the narrower pore was higher than in the wider pore, while the adsorbed amount per unit mass of carbon with the narrower pore was half of the amount of ACs with the larger pore. On the other hand, variations in the bands assigned to double-electron (KM I) and 1s  →  3d excitations in XAFS spectra demonstrate the formation of a distorted hydration cluster around Ca(2+) in the micropore, although the structural parameters of hydrated Ca(2+) in the micropores were almost consistent with the bulk aqueous solution, as revealed by the analysis of extended XAFS (EXAFS) spectra. In contrast to the hydration structure of monovalent ions such as Rb(+), which generally presents a dehydrated structure in smaller than 1 nm micropores in ACs, the present study clearly explains that the non-spherically-symmetric structure of hydrated Ca(2+) restricted in carbon micropores whose sizes are around 1 nm is experimentally revealed where any dehydration phenomena from the first hydration shell around Ca(2+) could not be observed. PMID:27624154

  18. Experimental study of spray cooling performance on micro-porous coated surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Yoon-Ho; Choi, Chihwan; Lee, Kyu-Jung; Han, Donghyouck

    2009-08-01

    Experiments on evaporative spray cooling of flat heaters with plain and micro-porous coated surfaces were performed in this study. Micro-porous coated surfaces were made by using the DOM [Diamond particle, Omegabond 101, Methyl-Ethyl-Keton] coating method. In pure air-jet cooling, micro-porous coating did not show heat transfer improvement over plain surface. In spray cooling, however, three different flow patterns (complete wetting, evaporative wetting and dryout) were observed on both plain and micro-porous coated surfaces. The effects of various operating conditions, such as water flow rate, particle size, and coating thickness on the micro-porous coated surface were investigated. It was found that the level of surface wetting was an important factor in determining the performance of spray cooling. The level of surface wetting depended on the balance between the amount of liquid absorbed by capillary force over porosity and the amount of liquid evaporated. A micro-porous coated surface has a very high cooling capacity, especially in the evaporative wetting zone. The liquid flow rate and coating thickness are significant factors in the evaporative wetting zone, but are not in the complete wetting zone and the dryout zone.

  19. Catalytic effect of transition metals on microwave-induced degradation of atrazine in mineral micropores.

    PubMed

    Hu, Erdan; Cheng, Hefa

    2014-06-15

    With their high catalytic activity for redox reactions, transition metal ions (Cu(2+) and Fe(3+)) were exchanged into the micropores of dealuminated Y zeolites to prepare effective microporous mineral sorbents for sorption and microwave-induced degradation of atrazine. Due to its ability to complex with atrazine, loading of copper greatly increased the sorption of atrazine. Atrazine sorption on iron-exchanged zeolites was also significantly enhanced, which was attributed to the hydrolysis of Fe(3+) polycations in mineral micropores and electrostatic interactions of protonated atrazine molecules with the negatively charged pore wall surface. Copper and iron species in the micropores also significantly accelerated degradation of the sorbed atrazine (and its degradation intermediates) under microwave irradiation. The catalytic effect was attributed to the easy reducibility and high oxidation activity of Cu(2+) and Fe(3+) species stabilized in the micropores of the zeolites. It was postulated that the surface species of transition metals (monomeric Cu(2+), Cu(2+)-O-Cu(2+) complexes, FeO(+), and dinuclear Fe-O-Fe-like species) in the mineral micropores were thermally activated under microwave irradiation, and subsequently formed highly reactive sites catalyzing oxidative degradation of atrazine. The transition metal-exchanged zeolites, particularly the iron-exchanged ones, were relatively stable when leached under acidic conditions, which suggests that they are reusable in sorption and microwave-induced degradation. These findings offer valuable insights on designing of effective mineral sorbents that can selectively uptake atrazine from aqueous solutions and catalyze its degradation under microwave irradiation.

  20. Membranes for Environmentally Friendly Energy Processes

    PubMed Central

    He, Xuezhong; Hägg, May-Britt

    2012-01-01

    Membrane separation systems require no or very little chemicals compared to standard unit operations. They are also easy to scale up, energy efficient, and already widely used in various gas and liquid separation processes. Different types of membranes such as common polymers, microporous organic polymers, fixed-site-carrier membranes, mixed matrix membranes, carbon membranes as well as inorganic membranes have been investigated for CO2 capture/removal and other energy processes in the last two decades. The aim of this work is to review the membrane systems applied in different energy processes, such as post-combustion, pre-combustion, oxyfuel combustion, natural gas sweetening, biogas upgrading, hydrogen production, volatile organic compounds (VOC) recovery and pressure retarded osmosis for power generation. Although different membranes could probably be used in a specific separation process, choosing a suitable membrane material will mainly depend on the membrane permeance and selectivity, process conditions (e.g., operating pressure, temperature) and the impurities in a gas stream (such as SO2, NOx, H2S, etc.). Moreover, process design and the challenges relevant to a membrane system are also being discussed to illustrate the membrane process feasibility for a specific application based on process simulation and economic cost estimation. PMID:24958426

  1. Coagulation Parameter Thresholds Associated with Non-Bleeding in the Eighth Hour of Adult Cardiac Surgical Post-Cardiotomy Extracorporeal Membrane Oxygenation.

    PubMed

    Riley, Jeffrey B; Schears, Gregory J; Nuttall, Gregory A; Oliver, William C; Ereth, Mark H; Dearani, Joseph A

    2016-06-01

    Excessive bleeding and allogeneic transfusion during adult post-cardiotomy venoarterial extracorporeal membrane oxygenation (ECMO) are potentially harmful and expensive. Balancing the inhibition of clotting and distinguishing surgical from non-surgical bleeding in post-operative period is difficult. The sensitivity of coagulation tests including Thromboelastography(®) (TEG) to predict chest tube drainage in the early hours of ECMO was examined with the use of receiver-operating characteristics (ROC). The results are useful to incorporate in clinical evidence-based algorithms to guide management decisions. In the eighth hour of ECMO, 26 of the 53 adult patients (49%) studied were identified as non-bleeders (less than 2.0 mL/kg/h). All had experienced various types of cardiac surgical procedures. Fifty-two percent were female and the group was 54 ± 19 (mean ± 1 SD) years old. The coagulation parameter threshold with the maximum sensitivity and specificity to predict non-bleeding at 8 hours on ECMO was the kaolin plus heparinase TEG maximum amplitude (KH-TEG MA) at a significant ROC threshold (t) > 50 mm. The activated partial thromboplastin time (aPTT) t < 49 seconds, KH-TEG alpha-angle t > 51°, and the kaolin activated clotting time (ACT) t < 148 seconds were sensitive predictors of non-bleeders. The whole-blood KH-TEG MA was superior to the plasma-based aPTT or International Normalization Ratio (INR) to predict bleeding in the eighth hour of ECMO. Using coagulation laboratory thresholds that predict non-bleeding can begin a process of identifying patients earlier that are likely to bleed. Awareness of these parameter thresholds may improve care through patient protection from unnecessary transfusion and prolonging the life of the ECMO circuit. An algorithm incorporating the ROC thresholds was created to help recognize surgical bleeding to minimize unnecessary transfusions. PMID:27578897

  2. Electrically Controlled Membranes Exploiting Cassie-Wenzel Wetting Transitions

    PubMed Central

    Bormashenko, Edward; Pogreb, Roman; Balter, Sagi; Aurbach, Doron

    2013-01-01

    We report electrically controlled membranes which become permeable when an electrical field is exerted on a droplet deposited on the membrane. Micro-porous polycarbonate membranes are obtained with the breath-figures assembly technique, using micro-scaled stainless steel gauzes as supports. The membranes demonstrate pronounced Cassie-Baxter wetting. Air cushions trapped by the droplet prevent water penetration through the membrane. We demonstrate two possibilities for controlling the permeability of the membrane, namely contact and non-contact scenarios. When an electrical field is exerted on a droplet deposited on the membrane, the triple-line is de-pinned and the wetting transition occurs in the non-contact scheme. Thus, the membrane becomes permeable. The contact scheme of the permeability control is based on the electrowetting phenomenon. PMID:24149769

  3. Fabrication of resorbable microporous intravascular stents for gene therapy applications.

    PubMed

    Rajasubramanian, G; Meidell, R S; Landau, C; Dollar, M L; Holt, D B; Willard, J E; Prager, M D; Eberhart, R C

    1994-01-01

    The authors have produced resorbable, microporous endoluminal stents from Poly-L-lactic acid (PLLA)/Poly epsilon-caprolactone (PCL) blends. Both helical and tube stent designs have been obtained by solvent casting and flotation-precipitation fabrication techniques. A range of PLLA/PCL blend ratios and process variables were employed to investigate their influence on mechanical properties, porosity, and degradation rate. Polymer blends with higher PLLA proportions exhibit higher elastic moduli and ultimate tensile strength, and lower elongation, porosity, and degradation rates than do materials with higher PCL content. Stents with suitable mechanical properties for deployment and support of the vessel wall were obtained. Poly(ethylene oxide) was incorporated into these devices using an acid swelling technique, opening the pore structure and improving the hydrophilic character, thereby enabling the uptake of recombinant adenoviral vectors. The 50:50 PLLA/PCL blended stents were impregnated with recombinant adenovirus (AdCMB beta Gal, encoding a nuclear localizing variant of Escherichia coli beta-galactosidase). Cultured CV-1 cells incubated with stents impregnated with the recombinant virus expressed nuclear localized beta-galactosidase activity, confirming that absorbed virus is released from the matrix in an infectious form, with kinetics suggesting that genetically enhanced endovascular devices of this design are feasible.

  4. Synthetic zeolites and other microporous oxide molecular sieves

    PubMed Central

    Sherman, John D.

    1999-01-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow “tailoring” of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

  5. Reverse Micelle Based Synthesis of Microporous Materials in Microgravity

    NASA Technical Reports Server (NTRS)

    Dutta, Prabir K.

    1995-01-01

    Formation of zincophosphates from zinc and phosphate containing reverse micelles (water droplets in hexane) has been examined. The frameworks formed resemble that made by conventional hydrothermal synthesis. Dynamics of crystal growth are however quite different, and form the main focus of this study. In particular, the formation of zincophosphate with the sodalite framework was examined in detail. The intramicellar pH was found to have a strong influence on crystal growth. Crystals with a cubic morphology were formed directly from the micelles, without an apparent intermediate amorphous phase over a period of four days by a layer-bylayer growth at the intramicellar pH of 7.6. At a pH of 6.8, an amorphous precipitate rapidly sediments in hours. Sodalite was eventually formed from this settled phase via surface diffusion and reconstruction within four days. With a rotating cell, it was possible to minimize sedimentation and crystals were found to grow epitaxially from the spherical, amorphous particles. Intermediate pH's of 7.2 led to formation of aggregated sodalite crystals prior to settling, again without any indication of an intermediate amorphous phase. These diverse pathways were possible due to changes in intramicellar supersaturation conditions by minor changes in pH. In contrast, conventional syntheses in this pH range all proceeded by similar crystallization pathways through an amorphous gel. This study establishes that synthesis of microporous frameworks is not only possible in reverse micellar systems, but they also allow examination of possible crystallization pathways.

  6. Synthetic zeolites and other microporous oxide molecular sieves.

    PubMed

    Sherman, J D

    1999-03-30

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

  7. Two supramolecular microporous frameworks stabilized by hydroxyl anionic water cluster

    NASA Astrophysics Data System (ADS)

    Jian, Fang Fang; Wang, Jing; Huang, Li Hua; Wang, Xian; Xiao, Hai Lian

    2010-06-01

    Two stable supramolecular microporous framework complexes, from the same [MCl(phen) 2] + (M = Cu, Ni), containing chiral hydroxyl anionic water cluster polymer, were synthesized, and their crystal structures were described. These supramolecular frameworks showed very high stability even if they were heated to 300 °C. Thermal analysis and powder X-ray diffraction results indicated that the water molecules were removed when heated from 150 °C to 300 °C without losing the main crystal framework. Water molecules can be reassembled by exposing the dehydrated form to an atmosphere saturated with water vapor. It indicated that the dehydrated form may be utilized as a potential absorbing agent for water and water vapor. The stable dehydrated form, [MCl(phen) 2][(OH)(H 2O)], suggested the stronger anionic H-bonding and intracluster proton transfer process OH -·H 2O → H 2O·OH -. The "anion- π interaction" was found in the crystal lattice of [MCl(phen) 2][(OH)(H 2O)]. This paper reported an example of supramolecular polymer with open channels that could be formed/collapse reversibly upon hydration/dehydration.

  8. Evaluation of microporous carbon filters as catalysts for ozone decomposition

    SciTech Connect

    Whinnery, L.; Coutts, D.; Shen, C.; Adams, R.; Quintana, C.; Showalter, S.

    1994-12-31

    Ozone is produced in small quantities in photocopiers and laser printers in the workplace and large quantities in industrial waste water treatment facilities. Carbon filters are commonly used to decompose this unwanted ozone. The three most important factors in producing a filter for this purpose are flow properties, efficiency, and cost. Most ozone decomposition applications require very low back-pressure at modest flow rates. The tradeoff between the number of pores and the size of the pores will be discussed. Typical unfiltered emissions in the workplace are approximately 1 ppm. The maximum permissible exposure limit, PEL, for worker exposure to ozone is 0.1 ppm over 8 hours. Several methods have been examined to increase the efficiency of ozone decomposition. Carbon surfaces were modified with catalysts, the surface activated, and the surface area was increased, in attempts to decompose ozone more effectively. Methods to reduce both the processing and raw material costs were investigated. Several sources of microporous carbon were investigated as ozone decomposition catalysts. Cheaper processing routes including macropore templating, faster drying and extracting methods were also studied.

  9. Mechanics considerations for microporous titanium as an orthopedic implant material.

    PubMed

    Thelen, Sarah; Barthelat, François; Brinson, L Catherine

    2004-06-15

    This article investigates mechanics issues related to potential use of a recently developed porous titanium (Ti) material for load-bearing implants. This material may have advantages over solid Ti of enhancing the bone-implant interface strength by promoting bone and soft tissue ingrowth and of reducing the bone-implant modulus mismatch, which can lead to stress shielding. Experimental data from ultrasound experiments and uniaxial compression testing on microporous Ti are presented. Analytic models to predict its elastic modulus and Poisson's ratio are discussed, including "structural" approaches (Gibson and Ashby's cellular solids) and a "composite material" approach (Mori-Tanaka). Finally, two-dimensional finite element models based on optical micrographs of the material are presented. Simulations were performed for different conditions and levels of approximation. Results demonstrate that simple analytic models provide good estimates of the elastic properties of the porous Ti and that the moduli can be significantly reduced to decrease the mismatch between solid Ti and bone. The finite element simulations show that bone ingrowth will dramatically reduce stress concentrations around the pores. PMID:15162401

  10. Preparation and evaluation of composite membranes for zinc/bromine storage batteries

    NASA Astrophysics Data System (ADS)

    Arnold, Charles, Jr.; Assink, Roger A.

    Low coulombic efficiencies of zinc/bromine redox batteries were attributed to migration of bromine and negatively charged bromine moieties through the microporous separator used to separate the catholyte from the anolyte. While it was demonstrated that improvements in coulombic efficiency can be achieved by replacing the microporous separator with a cationic ion exchange membrane, these membranes are expensive and/or not sufficiently conductive to be practicable. It was found that the rate of bromine permeation can be reduced by two orders of magnitude with minimal decreases in conductivity by impregnating commercial microporous polyethylene type separators with sulfonated polysulfone, a cationic polyelectrolyte that was developed in earlier work for other redox storage batteries.

  11. Preparation and evaluation of composite membranes for zinc/bromine storage batteries

    SciTech Connect

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

    1989-01-01

    Low coulombic efficiencies of zinc/bromine redox batteries have been attributed to migration of bromine and negatively charged bromine moieties through the microporous separator used to separate the catholyte from the anolyte. While it has been demonstrated that improvements in coulombic efficiency can be achieved by replacing the microporous separator with a cationic ion exchange membrane, these membranes are expensive and/or not sufficiently conductive to be practicable. We have found that the rate of bromine permeation can be reduced by two orders of magnitude with minimal decreases in conductivity by impregnating commercial microporous polyethylene type separators with sulfonated polysulfone, a cationic polyelectrolyte that was developed in earlier work for other redox storage batteries. 5 refs., 1 fig., 1 tab.

  12. Tuning microcavities in thermally rearranged polymer membranes for CO2 capture.

    PubMed

    Han, S H; Kwon, H J; Kim, K Y; Seong, J G; Park, C H; Kim, S; Doherty, C M; Thornton, A W; Hill, A J; Lozano, A E; Berchtold, K A; Lee, Y M

    2012-04-01

    Microporous materials have a great importance in catalysis, delivery, storage and separation in terms of their performance and efficiency. Most microporous materials are comprised of inorganic frameworks, while thermally rearranged (TR) polymers are a microporous organic polymer which is tuned to optimize the cavity sizes and distribution for difficult separation applications. The sub-nano sized microcavities are controlled by in situ thermal treatment conditions which have been investigated by positron annihilation lifetime spectroscopy (PALS). The size and relative number of cavities increased from room temperature to 230 °C resulting in improvements in both permeabilities and selectivities for H(2)/CO(2) separation due to the significant increase of gas diffusion and decrease of CO(2) solubility. The highest performance of the well-tuned TR-polymer membrane was 206 Barrer for H(2) permeability and 6.2 of H(2)/CO(2) selectivity, exceeding the polymeric upper bound for gas separation membranes.

  13. Development of Pd-Ag Compostie Membrane for Separation of Hydrogen at Elevated Temperature

    SciTech Connect

    Shamsuddin Ilias

    2009-02-28

    Pd-based membrane reactor offers the possibility of combining reaction and separation in a single operation at high temperatures to overcome the equilibrium limitations experienced in conventional reactor configurations. In this project to develop a defect-free and hermally-stable Pd-film on microporous stainless steel (MPSS) support for H2-separation and membrane reactor applications, the electroless plating process was revisited with an aim to improve the membrane morphology. Specifically, this study includes; (a) an improvement f activation step using Pulse Laser Deposition (PLD), (b) development of a novel surfactant induced electroless plating (SIEP) for depositing robust Pd-film on microporous support, and (c) application of Pd-membrane as membrane reactor in steam methanol reforming (SMR) reactions.

  14. Development of an alternating magnetic-field-assisted finishing process for microelectromechanical systems micropore x-ray optics.

    PubMed

    Riveros, Raul E; Yamaguchi, Hitomi; Mitsuishi, Ikuyuki; Takagi, Utako; Ezoe, Yuichiro; Kato, Fumiki; Sugiyama, Susumu; Yamasaki, Noriko; Mitsuda, Kazuhisa

    2010-06-20

    X-ray astronomy research is often limited by the size, weight, complexity, and cost of functioning x-ray optics. Micropore optics promises an economical alternative to traditional (e.g., glass or foil) x-ray optics; however, many manufacturing difficulties prevent micropore optics from being a viable solution. Ezoe et al. introduced microelectromechanical systems (MEMS) micropore optics having curvilinear micropores in 2008. Made by either deep reactive ion etching or x-ray lithography, electroforming, and molding (LIGA), MEMS micropore optics suffer from high micropore sidewall roughness (10-30nmrms) which, by current standards, cannot be improved. In this research, a new alternating magnetic-field-assisted finishing process was developed using a mixture of ferrofluid and microscale abrasive slurry. A machine was built, and a set of working process parameters including alternating frequency, abrasive size, and polishing time was selected. A polishing experiment on a LIGA-fabricated MEMS micropore optic was performed, and a change in micropore sidewall roughness of 9.3+/-2.5nmrms to 5.7+/-0.7nmrms was measured. An improvement in x-ray reflectance was also seen. This research shows the feasibility and confirms the effects of this new polishing process on MEMS micropore optics.

  15. Enhanced electric double-layer capacitance by desolvation of lithium ions in confined nanospaces of microporous carbon.

    PubMed

    Urita, Koki; Ide, Nozomi; Isobe, Kosuke; Furukawa, Hiroshi; Moriguchi, Isamu

    2014-04-22

    Carbon electrodes with specific microporous structures are strongly desired to improve the performance of electric double-layer capacitors (EDLCs). We report solvated states of Li ions in confined carbon micropores affecting specific capacitance. The average Li(+) solvation number of 1 M LiClO4/propylene carbonate (PC) electrolyte introduced into porous carbon electrodes was determined using Raman spectroscopy and (7)Li NMR. Micropores with slightly larger pore size against the solvated molecules and the narrow two-dimensional spaces decreased the solvation number, enhancing specific capacitance. Hence, specific carbon morphology may be related to high EDL capacitance, and micropore structure is important in obtaining highly capacitive EDLC materials. PMID:24646017

  16. Development of an alternating magnetic-field-assisted finishing process for microelectromechanical systems micropore x-ray optics

    SciTech Connect

    Riveros, Raul E.; Yamaguchi, Hitomi; Mitsuishi, Ikuyuki; Takagi, Utako; Ezoe, Yuichiro; Kato, Fumiki; Sugiyama, Susumu; Yamasaki, Noriko; Mitsuda, Kazuhisa

    2010-06-20

    X-ray astronomy research is often limited by the size, weight, complexity, and cost of functioning x-ray optics. Micropore optics promises an economical alternative to traditional (e.g., glass or foil) x-ray optics; however, many manufacturing difficulties prevent micropore optics from being a viable solution. Ezoe et al. introduced microelectromechanical systems (MEMS) micropore optics having curvilinear micropores in 2008. Made by either deep reactive ion etching or x-ray lithography, electroforming, and molding (LIGA), MEMS micropore optics suffer from high micropore sidewall roughness (10-30nmrms) which, by current standards, cannot be improved. In this research, a new alternating magnetic-field-assisted finishing process was developed using a mixture of ferrofluid and microscale abrasive slurry. A machine was built, and a set of working process parameters including alternating frequency, abrasive size, and polishing time was selected. A polishing experiment on a LIGA-fabricated MEMS micropore optic was performed, and a change in micropore sidewall roughness of 9.3{+-}2.5nmrms to 5.7{+-}0.7nmrms was measured. An improvement in x-ray reflectance was also seen. This research shows the feasibility and confirms the effects of this new polishing process on MEMS micropore optics.

  17. Resistance to biodegradative stress cracking in microporous vascular access grafts.

    PubMed

    Carson, R J; Edwards, A; Szycher, M

    1996-10-01

    Degradative cracking, more commonly known as "environmental stress cracking" (ESC) has been observed in many implanted polyetherurethane elastomers. This phenomenon has been attributed to biochemical and cellular interactions at the surface of the implanted material causing polymer chain cleavage. This may result in surface fissuring followed by the deep cracking associated with considerable biodegradation of the polymer, resulting in loss of mechanical strength and the formation of aneurysms in an in vivo situation. These cracking effects are believed to be due to mechanical stress combined with the oxidising actions of macrophages and giant cells, as surface cracking has been observed to occur directly under adherent macrophages on a polyetherurethane implant. These cells form part of the body's immune response which uses enzymes and reactive oxygen species (O2, O2-, and HO. and H2O2) to degrade foreign material. We describe a modification of an in vitro test method developed by Zaho et al. [1] using glass wool and a Hydrogen Peroxide/Cobalt (II) Chloride (H2O2/CoCl2) mixture to replicate the oxidising effects of macrophages in vivo. The modifications were made to establish a routine testing system for resistance to biodegradation which could be used to screen a range of polymers designed for use in microporous vascular grafts. The grafts are pre-stressed by a method devised by Stokes et al. [2] where each graft is stretched to a predetermined elongation over a mandrel and the strain is fixed by tying PTFE tape around each end of the mandrel. PMID:8913848

  18. Microporous titanosilicate AM-2: Rb-exchange and thermal behaviour

    SciTech Connect

    Doebelin, Nicola . E-mail: nicola@doebelin.org; Armbruster, Thomas

    2007-01-18

    Rb-exchange and thermal stability of the microporous titanosilicate AM-2 were analysed by powder X-ray diffraction, thermo-gravimetric analysis, and chemical analysis of the mother liquid after exchange. The dehydration and thermal stability of the exchanged structure were monitored with in situ high temperature powder X-ray diffraction. Crystal structures were refined with Rietveld methods at 25 and 400 deg. C. The AM-2 structure was found to incorporate Rb{sup +} by replacing K{sup +}. After four exchange cycles and 166 h reaction time at 90 deg. C, the chemical composition was refined to K{sub 0.18}Rb{sub 1.82}TiSi{sub 3}O{sub 9}.H{sub 2}O. Extrapolation suggests that higher exchange ratios may be obtained after further cycles. H{sub 2}O was expelled by heating, leading to a dehydrated structure at 360 deg. C. Dehydration was associated with a change of space group symmetry from orthorhombic P2{sub 1}2{sub 1}2{sub 1} to monoclinic P2{sub 1}, which proved to be reversible after rehydration. This change of symmetry leaves the AM-2 characteristic structural topology uninfluenced and causes only minor distortions. The monoclinic AM-2 structure breaks down above 600 deg. C to become X-ray amorphous, and at 750 deg. C a wadeite-type phase (K {sub x}Rb{sub 2-x}TiSi{sub 3}O{sub 9}) crystallises. This transformation is irreversible and leads to immobilisation of Rb{sup +}.

  19. Centrifugal membrane filtration -- Task 9

    SciTech Connect

    1996-08-01

    The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, to demonstrate applications for the SpinTek technology within the US Department of Energy (DOE) Environmental management (EM) Program. The technology uses supported microporous membranes rotating at high rpm, under pressure, to separate suspended and colloidal solids from liquid streams, yielding a solids-free permeate stream and a highly concentrated solids stream. This is a crosscutting technology that falls under the Efficient Separations and Processing Crosscutting Program, with potential application to tank wastes, contaminated groundwater, landfill leachate, and secondary liquid waste streams from other remediation processes, including decontamination and decommissioning systems. Membrane-screening tests were performed with the SpinTek STC-X4 static test cell filtration unit, using five ceramic membranes with different pore size and composition. Based on permeate flux, a 0.25-{micro}m TiO{sub 2}/Al{sub 2}O{sub 3} membrane was selected for detailed performance evaluation using the SpinTek ST-IIL centrifugal membrane filtration unit with a surrogate tank waste solution. An extended test run of 100 hr performed on a surrogate tank waste solution showed some deterioration in filtration performance, based on flux, apparently due to the buildup of solids near the inner portion of the membrane where relative membrane velocities were low. Continued testing of the system will focus on modifications to the shear pattern across the entire membrane surface to affect improved long-term performance.

  20. Role of transiently altered sarcolemmal membrane permeability and basic fibroblast growth factor release in the hypertrophic response of adult rat ventricular myocytes to increased mechanical activity in vitro.

    PubMed Central

    Kaye, D; Pimental, D; Prasad, S; Mäki, T; Berger, H J; McNeil, P L; Smith, T W; Kelly, R A

    1996-01-01

    One of the trophic factors that has been implicated in initiating or facilitating growth in response to increased mechanical stress in several tissues and cell types is basic fibroblast growth factor (bFGF; FGF-2). Although mammalian cardiac muscle cells express bFGF, it is not known whether it plays a role in mediating cardiac adaptation to increased load, nor how release of the cytosolic 18-kD isoform of bFGF would be regulated in response to increased mechanical stress. To test the hypothesis that increased mechanical activity induces transient alterations in sarcolemmal permeability that allow cytosolic bFGF to be released and subsequently to act as an autocrine and paracrine growth stimulus, we examined primary isolates of adult rat ventricular myocytes maintained in serum-free, defined medium that were continually paced at 3 Hz for up to 5 d. Paced myocytes, but not nonpaced control cells, exhibited a "hypertrophic" response, which was characterized by increases in the rate of phenylalanine incorporation, total cellular protein content, and cell size. These changes could be mimicked in control cells by exogenous recombinant bFGF and could be blocked in continually paced cells by a specific neutralizing anti-bFGF antibody. In addition, medium conditioned by continually paced myocytes contained significantly more bFGF measured by ELISA and more mitogenic activity for 3T3 cells, activity that could be reduced by a neutralizing anti-bFGF antibody. The hypothesis that transient membrane disruptions sufficient to allow release of cytosolic bFGF occur in paced myocytes was examined by monitoring the rate of uptake into myocytes from the medium of 10-kD dextran linked to fluorescein. Paced myocytes exhibited a significantly higher rate of fluoresceinlabeled dextran uptake. These data are consistent with the hypothesis that nonlethal, transient alterations in sarcolemmal membrane permeability with release of cytosolic bFGF is one mechanism by which increased

  1. Superporous thermo-responsive hydrogels by combination of cellulose fibers and aligned micropores.

    PubMed

    Halake, Kantappa S; Lee, Jonghwi

    2014-05-25

    In the area of artificial hydrogels, simultaneous engineering of the volume transition characteristics and mechanical properties of stimuli-responsive hydrogels is an important subject. By unrestricted architecting of hierarchical structures, natural hydrogels are able to provide a wide range of swelling and mechanical properties, beyond the limits of artificial hydrogels. Herein, a combination of nanostructures and microstructures was developed to construct superporous hydrogels. Fibers of microfibrillated cellulose (MFC), an eco-friendly reinforcing material, were used as nanostructures, aligned micropores were used as microstructures, and in situ photopolymerization was used to immobilize the two structures together within the gel networks of poly(N-isopropyl acrylamide) (PNIPAm). The introduction of MFC distinctly enhanced volume transition, mainly by decreasing the swelling ratios above the transition. The introduction of directional micropores increased the swelling ratio below the transition and decreased the swelling ratio above the transition, thereby also enhancing the volume transition. Additionally, the formation of aligned micropores achieved fast water infiltration, which is beneficial for superabsorbent applications. The introduction of aligned micropores reduced the elastic modulus, but this could partially be compensated for by reinforcement with MFC. This combination of crystalline nanofibers and aligned micropores has great potential for the development of stimuli-responsive superporous hydrogels outperforming current artificial hydrogels.

  2. An activated microporous carbon prepared from phenol-melamine-formaldehyde resin for lithium ion battery anode

    SciTech Connect

    Zhu, Yinhai; Xiang, Xiaoxia; Liu, Enhui; Wu, Yuhu; Xie, Hui; Wu, Zhilian; Tian, Yingying

    2012-08-15

    Highlights: ► Microporous carbon was prepared by chemical activation of phenol-melamine-formaldehyde resin. ► Activation leads to high surface area, well-developed micropores. ► Micropores lead to strong intercalation between carbon and lithium ion. ► Large surface area promotes to improve the lithium storage capacity. -- Abstract: Microporous carbon anode materials were prepared from phenol-melamine-formaldehyde resin by ZnCl{sub 2} and KOH activation. The physicochemical properties of the obtained carbon materials were characterized by scanning electron microscope, X-ray diffraction, Brunauer–Emmett–Teller, and elemental analysis. The electrochemical properties of the microporous carbon as anode materials in lithium ion secondary batteries were evaluated. At a current density of 100 mA g{sup −1}, the carbon without activation shows a first discharge capacity of 515 mAh g{sup −1}. After activation, the capacity improved obviously. The first discharge capacity of the carbon prepared by ZnCl{sub 2} and KOH activation was 1010 and 2085 mAh g{sup −1}, respectively. The reversible capacity of the carbon prepared by KOH activation was still as high as 717 mAh g{sup −1} after 20 cycles, which was much better than that activated by ZnCl{sub 2}. These results demonstrated that it may be a promising candidate as an anode material for lithium ion secondary batteries.

  3. Restricted access: on the nature of adsorption/desorption hysteresis in amorphous, microporous polymeric materials.

    PubMed

    Jeromenok, Jekaterina; Weber, Jens

    2013-10-22

    The phenomenon of low-pressure adsorption/desorption hysteresis, which is commonly observed in microporous polymers, is investigated by detailed gas adsorption studies. Diffusional limitations by pore blocking effects, which arise as a consequence of the micropore morphology and connectivity, are discussed as the origin of the hysteresis rather than swelling effects, which have been suggested previously. Micropores with narrow openings, which cannot be filled easily, are expected to be present next to open pores. Those pores are termed restricted-access pores and are only filled in the course of the adsorption process as a consequence of the increasing solvation pressure exhibited from already filled micropores. As a consequence of the results presented here, it is suggested to use the desorption branch in addition to the adsorption branch for the extraction of the porosity characteristics, such as specific surface area, pore volume, and pore size distribution. The magnitude of the low-pressure hysteresis might hence give an idea of the micropore connectivity, which is important information for potential applications.

  4. Effect of Thickness of HA-Coating on Microporous Silk Scaffolds Using Alternate Soaking Technology

    PubMed Central

    Zhu, Rui; Xue, Yingsen; Hao, Zhangying; Xie, Zhenghong; Fan, Xiangli; Fan, Hongbin

    2014-01-01

    Hydroxyapatite (HA) can be coated on various materials surface and has the function of osteogenicity. Microporous silk scaffold has excellent biocompatibility. In this study, alternate soaking technology was used to coat HA on microporous silk scaffolds. However, the cell proliferation was found to decrease with the increasing thickness (cycles of soaking) of HA-coating. This study aims to determine the best thickness (cycles of soaking) of HA-coating on microporous silk scaffolds. The SEM observation showed that group with one cycle of alternate soaking (1C-HA) has the most optimal porosity like non-HA-modified microporous silk scaffolds. The proliferation of osteoblasts has no significant difference between noncoated HA (N-HA) and 1C-HA groups, which are both significantly higher than those in two cycles of soaking (2C-HA) and three cycles of soaking (3C-HA) groups. The transcription levels of specific genes (runx2 and osteonectin) in osteoblasts of 1C-HA group were significantly higher than those of N-HA group. Moreover, the levels showed no significant difference among 1C-HA, 2C-HA, and 3C-HA groups. In conclusion, microporous silk scaffold with 1 cycle of HA-coating can combine the biocompatibility of silk and osteogenicity of HA. PMID:25093176

  5. Random lasing of microporous surface of Cr2+:ZnSe crystal induced by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Yang, Xianheng; Feng, Guoying; Yao, Ke; Yi, Jiayu; Zhang, Hong; Zhou, Shouhuan

    2015-06-01

    We demonstrate a random lasing emission based on microporous surface of Cr2+:ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10-4 Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ˜13 μm and smaller ones with ˜1.2 μm on the surface of Cr2+:ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr2+:ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr2+:ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength.

  6. Porous and Microporous Honeycomb Composites as Potential Boundary-Layer Bleed Materials

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Willis, B. P.; Schoenenberger, M.

    1997-01-01

    Results of an experimental investigation are presented in which the use of porous and microporous honeycomb composite materials is evaluated as an alternate to perforated solid plates for boundary-layer bleed in supersonic aircraft inlets. The terms "porous" and "microporous," respectively, refer to bleed orifice diameters roughly equal to and much less than the displacement thickness of the approach boundary-layer. A Baseline porous solid plate, two porous honeycomb, and three microporous honeycomb configurations are evaluated. The performance of the plates is characterized by the flow coefficient and relative change in boundary-layer profile parameters across the bleed region. The tests were conducted at Mach numbers of 1.27 and 1.98. The results show the porous honeycomb is not as efficient at removing mass compared to the baseline. The microporous plates were about equal to the baseline with one plate demonstrating a significantly higher efficiency. The microporous plates produced significantly fuller boundary-layer profiles downstream of the bleed region for a given mass flow removal rate than either the baseline or the porous honeycomb plates.

  7. Optical detection of pores in adipocyte membrane

    NASA Astrophysics Data System (ADS)

    Yanina, I. Yu.; Doubrovski, V. A.; Tuchin, V. V.

    2013-08-01

    Structures that can be interpreted as cytoplasm droplets leaking through the membrane are experimentally detected on the membranes of adipocytes using optical digital microscopy. The effect of an aqueous alcohol solution of brilliant green on the amount and sizes of structures is studied. It is demonstrated that the optical irradiation of the adipocytes that are sensitized with the aid of the brilliant green leads to an increase in the amount of structures (pores) after the irradiation. The experimental results confirm the existence of an earlier-proposed effect of photochemical action on the sensitized cells of adipose tissue that involves additional formation of pores in the membrane of the sensitized cell under selective optical irradiation. The proposed method for the detection of micropores in the membrane of adipose tissue based on the detection of the cytoplasm droplets leaking from the cell can be considered as a method for the optical detection of nanosized pores.

  8. Membrane based apparatus for measurement of volatile particles

    SciTech Connect

    Cheng, Meng-Dawn; Allman, Steve L.

    2014-07-08

    A vapor particle separator including a temperature controlled chamber for desorbing vapors from the particulates of an exhaust gas and a separation chamber including a micro porous membrane. The micro porous membrane provides an interface between at least one particle passageway and at least one vapor passageway through the separation chamber. The particle passageway extends from an entrance to the separation chamber to a particle exit from the separation chamber. The vapor passageway extends from the micro-porous membrane to a vapor exit from the separation chamber that is separate from the particle exit from the separation chamber.

  9. Silica/polyacrylonitrile hybrid nanofiber membrane separators via sol-gel and electrospinning techniques for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yanilmaz, Meltem; Lu, Yao; Zhu, Jiadeng; Zhang, Xiangwu

    2016-05-01

    Silica/polyacrylonitrile (SiO2/PAN) hybrid nanofiber membranes were fabricated by using sol-gel and electrospinning techniques and their electrochemical performance was evaluated for use as separators in lithium-ion batteries. The aim of this study was to design high-performance separator membranes with enhanced electrochemical performance and good thermal stability compared to microporous polyolefin membranes. In this study, SiO2 nanoparticle content up to 27 wt% was achieved in the membranes by using sol-gel technique. It was found that SiO2/PAN hybrid nanofiber membranes had superior electrochemical performance with good thermal stability due to their high SiO2 content and large porosity. Compared with commercial microporous polyolefin membranes, SiO2/PAN hybrid nanofiber membranes had larger liquid electrolyte uptake, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. SiO2/PAN hybrid nanofiber membranes with different SiO2 contents (0, 16, 19 and 27 wt%) were also assembled into lithium/lithium iron phosphate cells, and high cell capacities and good cycling performance were demonstrated at room temperature. In addition, cells using SiO2/PAN hybrid nanofiber membranes with high SiO2 contents showed superior C-rate performance compared to those with low SiO2 contents and commercial microporous polyolefin membrane.

  10. A novel method to fabricate high permeance, high selectivity thin-film composite membranes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report a thin-film composite (TFC) membrane fabrication method based on transfer of a pre-formed, cured active layer onto a microporous support. This method can be used with supports of relatively high pore size and porosity, thus reducing mass transfer resistance from the support. Ethanol-select...

  11. 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.

  12. High-temperature stability and saturation magnetization of superparamagnetic nickel nanoparticles in microporous polysilazane-derived ceramics and their gas permeation properties.

    PubMed

    Seifollahi Bazarjani, Mahdi; Müller, Mathis M; Kleebe, Hans-Joachim; Jüttke, Yvonne; Voigt, Ingolf; Baghaie Yazdi, Mehrdad; Alff, Lambert; Riedel, Ralf; Gurlo, Aleksander

    2014-08-13

    Superparamagnetic Ni nanoparticles with diameters of about 3 nm are formed in situ at room temperature in a polysilazane matrix, forming Ni/polysilazane nanocomposite, in the reaction between a polysilazane and trans-bis(aceto-kO)bis(2-aminoethanol-k(2)N,O)nickel(II). The thermolysis of the Ni/polysilazane nanocomposite at 700 °C in an argon atmosphere results in a microporous superparamagnetic Ni/silicon oxycarbonitride (Ni/SiCNO) ceramic nanocomposite. The growth of Ni nanoparticles in Ni/SiCNO ceramic nanocomposite is totally suppressed even after thermolysis at 700 °C, as confirmed by HRTEM and SQUID characterizations. The analysis of saturation magnetization of Ni nanoparticles in Ni/polysilazane and Ni/SiCNO nanocomposites indicates that the saturation magnetization of Ni nanoparticles is higher than expected values and infers that the surfaces of Ni nanoparticles are not oxidized. The microporous superparamagnetic Ni/SiCNO nanocomposite is shaped as a free-standing monolith and foam. In addition, Ni/SiCNO membranes are fabricated by the dip-coating of a tubular alumina substrate in a dispersion of Ni/polysilazane in THF followed by a thermolysis at 700 °C under an argon atmosphere. The gas separation performance of Ni/SiCNO membranes at 25 and 300 °C is assessed by the single gas permeance (pressure rise technique) using He, H2, CO2, N2, CH4, n-propene, n-propane, n-butene, n-butane, and SF6 as probe molecules. After hydrothermal treatment, the higher increase in the hydrogen permeance compared to the permeance of other gases as a function of temperature indicates that the hydrogen affinity of Ni nanoparticles influences the transport of hydrogen in the Ni/SiCNO membrane and Ni nanoparticles stabilize the structure against hydrothermal corrosion. PMID:25014337

  13. Hierarchical mesoporous/microporous carbon with graphitized frameworks for high-performance lithium-ion batteries

    SciTech Connect

    Lv, Yingying; Fang, Yin; Qian, Xufang; Tu, Bo; Wu, Zhangxiong; Asiri, Abdullah M.; Zhao, Dongyuan

    2014-11-01

    A hierarchical meso-/micro-porous graphitized carbon with uniform mesopores and ordered micropores, graphitized frameworks, and extra-high surface area of ∼2200 m{sup 2}/g, was successfully synthesized through a simple one-step chemical vapor deposition process. The commercial mesoporous zeolite Y was utilized as a meso-/ micro-porous template, and the small-molecule methane was employed as a carbon precursor. The as-prepared hierarchical meso-/micro-porous carbons have homogeneously distributed mesopores as a host for electrolyte, which facilitate Li{sup +} ions transport to the large-area micropores, resulting a high reversible lithium ion storage of 1000 mA h/g and a high columbic efficiency of 65% at the first cycle.

  14. Methyllithium-Doped Naphthyl-Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance.

    PubMed

    Xu, Dan; Sun, Lei; Li, Gang; Shang, Jin; Yang, Rui-Xia; Deng, Wei-Qiao

    2016-06-01

    Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol(-1) and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target.

  15. Sorption of phenanthrene and benzene on differently structural kerogen: important role of micropore-filling.

    PubMed

    Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong

    2014-02-01

    Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (Vo,d) initially increase and then decrease. The Vo,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The Vo,d of phenanthrene and benzene on the kerogen samples accounts for 23-46% and 36-65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling.

  16. Manganese oxide nanowires, films, and membranes and methods of making

    DOEpatents

    Suib, Steven Lawrence; Yuan, Jikang

    2008-10-21

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer are substantially axially aligned.

  17. High temperature catalytic membrane reactors

    SciTech Connect

    Not Available

    1990-03-01

    Current state-of-the-art inorganic oxide membranes offer the potential of being modified to yield catalytic properties. The resulting modules may be configured to simultaneously induce catalytic reactions with product concentration and separation in a single processing step. Processes utilizing such catalytically active membrane reactors have the potential for dramatically increasing yield reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity. Examples of commercial interest include hydrogenation, dehydrogenation, partial and selective oxidation, hydrations, hydrocarbon cracking, olefin metathesis, hydroformylation, and olefin polymerization. A large portion of the most significant reactions fall into the category of high temperature, gas phase chemical and petrochemical processes. Microporous oxide membranes are well suited for these applications. A program is proposed to investigate selected model reactions of commercial interest (i.e. dehydrogenation of ethylbenzene to styrene and dehydrogenation of butane to butadiene) using a high temperature catalytic membrane reactor. Membranes will be developed, reaction dynamics characterized, and production processes developed, culminating in laboratory-scale demonstration of technical and economic feasibility. As a result, the anticipated increased yield per reactor pass economic incentives are envisioned. First, a large decrease in the temperature required to obtain high yield should be possible because of the reduced driving force requirement. Significantly higher conversion per pass implies a reduced recycle ratio, as well as reduced reactor size. Both factors result in reduced capital costs, as well as savings in cost of reactants and energy.

  18. Controlling the porosity of microporous silica by sol-gel processing using an organic template approach

    SciTech Connect

    Lu, Y.; Cao, G.Z.; Kale, R.P.; Delattre, L.; Lopez, G.P.; Brinker, C.J. |

    1996-12-31

    The authors use an organic template approach to prepare microporous silica with controlled pore size and narrow pore size distributions. This was accomplished by fabricating relatively dense hybrid silica matrices incorporating organic template ligands by sol-gel synthesis and then removing the organic ligands to create a microporous silica network. Comparison of computer simulation results and experimental data indicated that using this fugitive template approach, pore volume can be controlled by the amount of organic template added to the system, and pore size can be controlled by the size of the organic ligands.

  19. Metal-organic framework@microporous organic network: hydrophobic adsorbents with a crystalline inner porosity.

    PubMed

    Chun, Jiseul; Kang, Sungah; Park, Nojin; Park, Eun Ji; Jin, Xing; Kim, Kwang-Dae; Seo, Hyun Ook; Lee, Sang Moon; Kim, Hae Jin; Kwon, Woo Hyun; Park, Young-Kwon; Kim, Ji Man; Kim, Young Dok; Son, Seung Uk

    2014-05-14

    This work reports the synthesis and application of metal-organic framework (MOF)@microporous organic network (MON) hybrid materials. Coating a MOF, UiO-66-NH2, with MONs forms hybrid microporous materials with hydrophobic surfaces. The original UiO-66-NH2 shows good wettability in water. In comparison, the MOF@MON hybrid materials float on water and show excellent performance for adsorption of a model organic compound, toluene, in water. Chemical etching of the MOF results in the formation of hollow MON materials. PMID:24786337

  20. Applications of membrane processes for in-process materials recycling

    SciTech Connect

    Kim, B.M.; Thornton, R.F.; Shapiro, A.P.; Freshour, A.R.; El-Shoubary, Y.

    1996-12-31

    Zero discharge of wastes should be the ultimate goal of manufacturers. Waste reduction lowers costs and lessens liability associated with plant effluents. One approach toward this goal is elimination or minimization of wastes by in-process recycling of waste materials. We have examined opportunities for waste minimization for many equipment manufacturing plants and have evaluated membrane processes for in-process recycling. Membrane processes evaluated include vibrating membranes for suspended solid removal, ion exchange membranes for acid recovery, reverse osmosis and electrodialysis for dissolved salt removal, microporous membranes for recycling of machining coolants, oil emulsions, alkaline cleaners and others. This paper presents several examples of evaluations of membrane processes for materials recycling in manufacturing plants. 5 figs., 1 tab.

  1. TNF-α triggers rapid membrane insertion of Ca(2+) permeable AMPA receptors into adult motor neurons and enhances their susceptibility to slow excitotoxic injury.

    PubMed

    Yin, Hong Z; Hsu, Cheng-I; Yu, Stephen; Rao, Shyam D; Sorkin, Linda S; Weiss, John H

    2012-12-01

    Excitotoxicity (caused by over-activation of glutamate receptors) and inflammation both contribute to motor neuron (MN) damage in amyotrophic lateral sclerosis (ALS) and other diseases of the spinal cord. Microglial and astrocytic activation in these conditions results in release of inflammatory mediators, including the cytokine, tumor necrosis factor-alpha (TNF-α). TNF-α has complex effects on neurons, one of which is to trigger rapid membrane insertion of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type glutamate receptors, and in some cases, specific insertion of GluA2 lacking, Ca(2+) permeable AMPA receptors (Ca-perm AMPAr). In the present study, we use a histochemical stain based upon kainate stimulated uptake of cobalt ions ("Co(2+) labeling") to provide the first direct demonstration of the presence of substantial numbers of Ca-perm AMPAr in ventral horn MNs of adult rats under basal conditions. We further find that TNF-α exposure causes a rapid increase in the numbers of these receptors, via a phosphatidylinositol 3 kinase (PI3K) and protein kinase A (PKA) dependent mechanism. Finally, to assess the relevance of TNF-α to slow excitotoxic MN injury, we made use of organotypic spinal cord slice cultures. Co(2+) labeling revealed that MNs in these cultures possess Ca-perm AMPAr. Addition of either a low level of TNF-α, or of the glutamate uptake blocker, trans-pyrrolidine-2,4-dicarboxylic acid (PDC) to the cultures for 48 h resulted in little MN injury. However, when combined, TNF-α+PDC caused considerable MN degeneration, which was blocked by the AMPA/kainate receptor blocker, 2,3-Dihydroxy-6-nitro-7-sulfamoylbenzo (F) quinoxaline (NBQX), or the Ca-perm AMPAr selective blocker, 1-naphthyl acetylspermine (NASPM). Thus, these data support the idea that prolonged TNF-α elevation, as may be induced by glial activation, acts in part by increasing the numbers of Ca-perm AMPAr on MNs to enhance injurious excitotoxic effects of deficient

  2. Microstructure investigation on micropore formation in microporous silica materials prepared via a catalytic sol-gel process by small angle X-ray scattering.

    PubMed

    Shimizu, Wataru; Hokka, Junsuke; Sato, Takaaki; Usami, Hisanao; Murakami, Yasushi

    2011-08-01

    The so-called sol-gel technique has been shown to be a template-free, efficient way to create functional porous silica materials having uniform micropores. This appears to be closely linked with a postulation that the formation of weakly branched polymer-like aggregates in a precursor solution is a key to the uniform micropore generation. However, how such a polymer-like structure can precisely be controlled, and further, how the generated low-fractal dimension solution structure is imprinted on the solid silica materials still remain elusive. Here we present fabrication of microporous silica from tetramethyl orthosilicate (TMOS) using a recently developed catalytic sol-gel process based on a nonionic hydroxyacetone (HA) catalyst. Small angle X-ray scattering (SAXS), nitrogen adsorption porosimetry, and transmission electron microscope (TEM) allowed us to observe the whole structural evolution, ranging from polymer-like aggregates in the precursor solution to agglomeration with heat treatment and microporous morphology of silica powders after drying and hydrolysis. Using the HA catalyst with short chain monohydric alcohols (methanol or ethanol) in the precursor solution, polymer-like aggregates having microscopic correlation length (or mesh-size) < 2 nm and low fractal dimensions ∼2, which is identical to that of an ideal coil polymer, can selectively be synthesized, yielding the uniform micropores with diameters <2 nm in the solid materials. In contrast, the absence of HA or substitution of 1-propanol led to considerably different scattering behavior reflecting the particle-like aggregate formation in the precursor solution, which resulted in the formation of mesopores (diameter >2 nm) in the solid product due to apertures between the particle-like aggregates. The data demonstrate that the extremely fine porous silica architecture comes essentially from a gaussian polymer-like nature of the silica aggregates in the precursor having the microscopic mesh-size and

  3. Synthesis, characterization, and application of novel microporous mixed metal oxides, and nanostructured layered material-polymer films

    NASA Astrophysics Data System (ADS)

    Jeong, Hae-Kwon

    Zeolites are microporous crystalline aluminosilicates with pores and cavities of molecular dimension. They consist of interconnected aluminum and silicon tetrahedra to build a variety of 3D open framework structures. Due to their structure, stability, and activity, zeolites have been widely used in a broad variety of applications in industry. It is, therefore, of great interest to make new structures with potentially novel properties. In this regard, there has recently been a growing interest in the synthesis of novel mixed metal oxides with octahedral and tetrahedral units owing to the possibility to find unique electronic and optical properties. Hence, these materials can find advanced applications as well as conventional applications, just like zeolites. Research efforts have led to the discovery of several mixed octahedral and tetrahedral metal oxides with novel crystal structures including titanium silicates and cerium silicate. Layered materials with transport paths along the thickness of the layers are of particular interest due to potential usage as selective layers of nanometer scale in nanocomposite membranes. A new layered silicate (we call AMH-3) has been synthesized under hydrothermal conditions. The crystal structure solution via powder X-ray diffraction has revealed its unique layer structure of three dimensional microporosity within layers. Layered materials with porous layers will open up new areas of applications, such as selective nanocomposite separation membranes. Polymer/selective-flake nanocomposite membranes have been fabricated for the first time, which can, in principle, be scaled down to submicrometer structures. A layered aluminophosphate with a porous net layer is used as a selective phase and a polyimide as a continuous phase. The microstructures of the nanocomposite membranes were investigated using various characterization techniques. Nanocomposite membranes with 10 wt% layered aluminophosphate show substantial enhancement in

  4. Comparison of Intraprostatic Ethanol Diffusion Using a Microporous Hollow Fiber Catheter Versus a Standard Needle

    PubMed Central

    King, Benjamin J.; Plante, Mark K.; Kida, Masatoshi; Mann-Gow, Travis K.; Odland, Rick; Zvara, Peter

    2013-01-01

    Purpose Transurethral intraprostatic ethanol chemoablation of the prostate has shown promising preliminary clinical results for benign prostatic hyperplasia with some variability in clinical outcome. This is likely due to the uneven prostate diffusion caused by varying resistance of the tissue type in which the tip of the needle is embedded. We examined whether the distribution of the injectable in the canine prostate could be improved using a microporous hollow fiber catheter (Twin Star Medical, Minneapolis, Minnesota). Materials and Methods The prostate was exposed in 9 mongrel dogs. A single injection of 98% ethanol was delivered in each lobe using a microporous hollow fiber catheter and a standard needle. Prostates were harvested and fixed in 10% formalin. After injection 2.5 mm step sections were obtained and scanned. The ethanol induced tissue lesions were traced on hematoxylin and eosin sections. Three-dimensional reconstructions were created and the volume of each prostate lesion was calculated using stereology. Results Ethanol induced tissue changes were seen bilaterally in 8 of 9 ethanol injected prostates. In all cases the lesion created by microporous hollow fiber catheter injection was larger than that in the contralateral lobe injected with the control needle. When data were pooled, the hollow fiber catheter injection produced significantly greater tissue changes than the control needle injection (p = 0.03). Conclusions Improved distribution and absent backflow were seen when using the microporous hollow fiber catheter, supporting its potential as a new method to treat prostate disease. PMID:22425049

  5. Unidirectional Fast Growth and Forced Jumping of Stretched Droplets on Nanostructured Microporous Surfaces.

    PubMed

    Aili, Abulimiti; Li, Hongxia; Alhosani, Mohamed H; Zhang, TieJun

    2016-08-24

    Superhydrophobic nanostructured surfaces have demonstrated outstanding capability in energy and water applications by promoting dropwise condensation, where fast droplet growth and efficient condensate removal are two key parameters. However, these parameters remain contradictory. Although efficient droplet removal is easily obtained through coalescence jumping on uniform superhydrophobic surfaces, simultaneously achieving fast droplet growth is still challenging. Also, on such surfaces droplets can grow to larger sizes without restriction if there is no coalescence. In this work, we show that superhydrophobic nanostructured microporous surfaces can manipulate the droplet growth and jumping. Microporous surface morphology effectively enhances the growth of droplets in pores owing to large solid-liquid contact area. At low supersaturations, the upward growth rate (1-1.5 μm/s) of these droplets in pores is observed to be around 15-25 times that of the droplets outside the pores. Meanwhile, their top curvature radius increases relatively slowly (∼0.25 μm/s) due to pore confinement, which results in a highly stretched droplet surface. We also observed forced jumping of stretched droplets in pores either through coalescence with spherical droplets outside pores or through self-pulling without coalescence. Both experimental observation and theoretical modeling reveal that excess surface free energy stored in the stretched droplet surface and micropore confinement are responsible for this pore-scale-forced jumping. These findings reveal the insightful physics of stretched droplet dynamics and offer guidelines for the design and fabrication of novel super-repellent surfaces with microporous morphology.

  6. Unidirectional Fast Growth and Forced Jumping of Stretched Droplets on Nanostructured Microporous Surfaces.

    PubMed

    Aili, Abulimiti; Li, Hongxia; Alhosani, Mohamed H; Zhang, TieJun

    2016-08-24

    Superhydrophobic nanostructured surfaces have demonstrated outstanding capability in energy and water applications by promoting dropwise condensation, where fast droplet growth and efficient condensate removal are two key parameters. However, these parameters remain contradictory. Although efficient droplet removal is easily obtained through coalescence jumping on uniform superhydrophobic surfaces, simultaneously achieving fast droplet growth is still challenging. Also, on such surfaces droplets can grow to larger sizes without restriction if there is no coalescence. In this work, we show that superhydrophobic nanostructured microporous surfaces can manipulate the droplet growth and jumping. Microporous surface morphology effectively enhances the growth of droplets in pores owing to large solid-liquid contact area. At low supersaturations, the upward growth rate (1-1.5 μm/s) of these droplets in pores is observed to be around 15-25 times that of the droplets outside the pores. Meanwhile, their top curvature radius increases relatively slowly (∼0.25 μm/s) due to pore confinement, which results in a highly stretched droplet surface. We also observed forced jumping of stretched droplets in pores either through coalescence with spherical droplets outside pores or through self-pulling without coalescence. Both experimental observation and theoretical modeling reveal that excess surface free energy stored in the stretched droplet surface and micropore confinement are responsible for this pore-scale-forced jumping. These findings reveal the insightful physics of stretched droplet dynamics and offer guidelines for the design and fabrication of novel super-repellent surfaces with microporous morphology. PMID:27486890

  7. Micropore extrusion-induced alignment transition from perpendicular to parallel of cylindrical domains in block copolymers

    NASA Astrophysics Data System (ADS)

    Qu, Ting; Zhao, Yongbin; Li, Zongbo; Wang, Pingping; Cao, Shubo; Xu, Yawei; Li, Yayuan; Chen, Aihua

    2016-02-01

    The orientation transition from perpendicular to parallel alignment of PEO cylindrical domains of PEO-b-PMA(Az) films has been demonstrated by extruding the block copolymer (BCP) solutions through a micropore of a plastic gastight syringe. The parallelized orientation of PEO domains induced by this micropore extrusion can be recovered to perpendicular alignment via ultrasonication of the extruded BCP solutions and subsequent annealing. A plausible mechanism is proposed in this study. The BCP films can be used as templates to prepare nanowire arrays with controlled layers, which has enormous potential application in the field of integrated circuits.The orientation transition from perpendicular to parallel alignment of PEO cylindrical domains of PEO-b-PMA(Az) films has been demonstrated by extruding the block copolymer (BCP) solutions through a micropore of a plastic gastight syringe. The parallelized orientation of PEO domains induced by this micropore extrusion can be recovered to perpendicular alignment via ultrasonication of the extruded BCP solutions and subsequent annealing. A plausible mechanism is proposed in this study. The BCP films can be used as templates to prepare nanowire arrays with controlled layers, which has enormous potential application in the field of integrated circuits. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09140c

  8. Structural micro-porous carbon anode for rechargeable lithium-ion batteries

    DOEpatents

    Delnick, F.M.; Even, W.R. Jr.; Sylwester, A.P.; Wang, J.C.F.; Zifer, T.

    1995-06-20

    A secondary battery having a rechargeable lithium-containing anode, a cathode and a separator positioned between the cathode and anode with an organic electrolyte solution absorbed therein is provided. The anode comprises three-dimensional microporous carbon structures synthesized from polymeric high internal phase emulsions or materials derived from this emulsion source, i.e., granules, powders, etc. 6 figs.

  9. MicroRNA functionalized microporous titanium oxide surface by lyophilization with enhanced osteogenic activity.

    PubMed

    Wu, Kaimin; Song, Wen; Zhao, Lingzhou; Liu, Mengyuan; Yan, Jun; Andersen, Morten Østergaard; Kjems, Jørgen; Gao, Shan; Zhang, Yumei

    2013-04-10

    Developing biomedical titanium (Ti) implants with high osteogenic ability and consequent rigid osseointegration is a constant requirement from the clinic. In this study, we fabricate novel miRNA functionalized microporous Ti implants by lyophilizing miRNA lipoplexes onto a microporous titanium oxide surface formed by microarc oxidation (MAO). The microporous titanium oxide surface provides a larger surface area for miRNA loading and enables spatial retention of the miRNAs within the pores until cellular delivery. The loading of lipoplexes into the micropores on the MAO Ti surface is facilitated by the superhydrophilicity and Ti-OH groups gathering of the MAO surface after UV irradiation followed by lyophilization. A high miRNA transfection efficiency was observed in mesenchymal stem cells (MSCs) seeded onto the miRNA functionalized surface with no apparent cytotoxicity. When functionalizing the Ti surface with miR-29b that enhances osteogenic activity and antimiR-138 that inhibits miR-138 inhibition of endogenous osteogenesis, clear stimulation of MSC osteogenic differentiation was observed, in terms of up-regulating osteogenic expression and enhancing alkaline phosphatase production, collagen secretion and ECM mineralization. The novel miRNA functionalized Ti implants with enhanced osteogenic activity promisingly lead to more rapid and robust osseointegration of a clinical bone implant interface. Our study implies that lyophilization may constitute a versatile method for miRNA loading to other biomaterials with the aim of controlling cellular function. PMID:23459382

  10. Modelling the effect of wettability distributions on oil recovery from microporous carbonate reservoirs

    NASA Astrophysics Data System (ADS)

    Kallel, W.; van Dijke, M. I. J.; Sorbie, K. S.; Wood, R.; Jiang, Z.; Harland, S.

    2016-09-01

    Carbonate-hosted hydrocarbon reservoirs are known to be weakly- to moderately oil-wet, but the pore-scale wettability distribution is poorly understood. Moreover, micropores, which often dominate in carbonate reservoirs, are usually assumed to be water-wet and their role in multi-phase flow is neglected. Modelling the wettability of carbonates using pore network models is challenging, because of our inability to attribute appropriate chemical characteristics to the pore surfaces and over-simplification of the pore shapes. Here, we implement a qualitatively plausible wettability alteration scenario in a two-phase flow network model that captures a diversity of pore shapes. The model qualitatively reproduces patterns of wettability alteration recently observed in microporous carbonates via high-resolution imaging. To assess the combined importance of pore-space structure and wettability on petrophysical properties, we consider a homogeneous Berea sandstone network and a heterogeneous microporous carbonate network, whose disconnected coarse-scale pores are connected through a sub-network of fine-scale pores. Results demonstrate that wettability effects are significantly more profound in the carbonate network, as the wettability state of the micropores controls the oil recovery.

  11. Effect of Processing Variables on the Microstructure and Mechanical Properties of Microporous Carbon Materials

    NASA Technical Reports Server (NTRS)

    Singh, M.; Dacek, R. F.

    1996-01-01

    Microporous carbon materials with different pore and strut sizes have been fabricated by the pyrolysis of furfuryl alcohol resin, triethylene glycol, and p-toluene sulfonic acid mixtures. The resulting materials were characterized by scanning electron microscopy and density measurements. The room temperature flexural strength and modulus of these materials decreases with increasing amount of acid curing agent.

  12. Microporous polyurethane material for size selective heterogeneous catalysis of the Knoevenagel reaction.

    PubMed

    Dey, Sandeep Kumar; de Sousa Amadeu, Nader; Janiak, Christoph

    2016-06-14

    The first polyurethane material which is microporous (BET surface area of 312 m(2) g(-1)) is prepared by solvothermal synthesis and acts as highly efficient and recyclable heterogeneous catalyst in the Knoevenagel condensation showing size selectivity, and in the Henry reaction showing substrate selectivity under mild reaction conditions. PMID:27240738

  13. A highly crystalline microporous hybrid organic-inorganic aluminosilicate resembling the AFI-type zeolite.

    PubMed

    Bellussi, Giuseppe; Millini, Roberto; Montanari, Erica; Carati, Angela; Rizzo, Caterina; Parker, Wallace O; Cruciani, Giuseppe; de Angelis, Alberto; Bonoldi, Lucia; Zanardi, Stefano

    2012-07-28

    ECS-14, a crystalline microporous hybrid organic-inorganic aluminosilicate, has been synthesized by using 1,4-bis-(triethoxysilyl)-benzene (BTEB) as a source of silica. Its structure contains a system of linear channels with 12-membered ring openings, running along the [001] direction, resembling the pore architecture of the AFI framework type. PMID:22717682

  14. Size and spacial distribution of micropores in SBA-15 using CM-SANS

    SciTech Connect

    Pollock, Rachel A; Walsh, Brenna R; Fry, Jason A; Ghampson, Tyrone; Centikol, Ozgul; Melnichenko, Yuri B; Kaiser, Helmut; Pynn, Roger; Frederick, Brian G

    2011-01-01

    Diffraction intensity analysis of small-angle neutron scattering measurements of dry SBA-15 have been combined with nonlocal density functional theory (NLDFT) analysis of nitrogen desorption isotherms to characterize the micropore, secondary mesopore, and primary mesopore structure. The radial dependence of the scattering length density, which is sensitive to isolated surface hydroxyls, can only be modeled if the NLDFT pore size distribution is distributed relatively uniformly throughout the silica framework, not localized in a 'corona' around the primary mesopores. Contrast matching-small angle neutron scattering (CM-SANS) measurements, using water, decane, tributylamine, cyclohexane, and isooctane as direct probes of the size of micropores indicate that the smallest pores in SBA-15 have diameter between 5.7 and 6.2 {angstrom}. Correlation of the minimum pore size with the onset of the micropore size distribution provides direct evidence that the shape of the smallest micropores is cylinderlike, which is consistent with their being due to unraveling of the polymer template.

  15. Homochiral Crystallization of Microporous Framework Materials from Achiral Precursors by Chiral Catalysis

    PubMed Central

    Zhang, Jian; Chen, Shumei; Wu, Tao; Feng, Pingyun; Bu, Xianhui

    2009-01-01

    While it is not uncommon to form chiral crystals during crystallization, the formation of bulk porous homochiral materials from achiral building units is rare. Reported here is the homochiral crystallization of microporous materials through the chirality induction effect of natural alkaloids. The resulting material possesses permanent microporosity and has a uniform pore size of 9.3Å. PMID:18774816

  16. Doppler optical coherence tomography imaging of local fluid flow and shear stress within microporous scaffolds

    NASA Astrophysics Data System (ADS)

    Jia, Yali; Bagnaninchi, Pierre O.; Yang, Ying; Haj, Alicia El; Hinds, Monica T.; Kirkpatrick, Sean J.; Wang, Ruikang K.

    2009-05-01

    Establishing a relationship between perfusion rate and fluid shear stress in a 3D cell culture environment is an ongoing and challenging task faced by tissue engineers. We explore Doppler optical coherence tomography (DOCT) as a potential imaging tool for in situ monitoring of local fluid flow profiles inside porous chitosan scaffolds. From the measured fluid flow profiles, the fluid shear stresses are evaluated. We examine the localized fluid flow and shear stress within low- and high-porosity chitosan scaffolds, which are subjected to a constant input flow rate of 0.5 ml.min-1. The DOCT results show that the behavior of the fluid flow and shear stress in micropores is strongly dependent on the micropore interconnectivity, porosity, and size of pores within the scaffold. For low-porosity and high-porosity chitosan scaffolds examined, the measured local fluid flow and shear stress varied from micropore to micropore, with a mean shear stress of 0.49+/-0.3 dyn.cm-2 and 0.38+/-0.2 dyn.cm-2, respectively. In addition, we show that the scaffold's porosity and interconnectivity can be quantified by combining analyses of the 3D structural and flow images obtained from DOCT.

  17. Structural micro-porous carbon anode for rechargeable lithium-ion batteries

    DOEpatents

    Delnick, Frank M.; Even, Jr., William R.; Sylwester, Alan P.; Wang, James C. F.; Zifer, Thomas

    1995-01-01

    A secondary battery having a rechargeable lithium-containing anode, a cathode and a separator positioned between the cathode and anode with an organic electrolyte solution absorbed therein is provided. The anode comprises three-dimensional microporous carbon structures synthesized from polymeric high internal phase emulsions or materials derived from this emulsion source, i.e., granules, powders, etc.

  18. Membrane Extraction for Detoxification of Biomass Hydrolysates

    SciTech Connect

    Grzenia, D. L.; Schell, D. J.; Wickramasinghe, S. R.

    2012-05-01

    Membrane extraction was used for the removal of sulfuric acid, acetic acid, 5-hydroxymethyl furfural and furfural from corn stover hydrolyzed with dilute sulfuric acid. Microporous polypropylene hollow fiber membranes were used. The organic extractant consisted of 15% Alamine 336 in: octanol, a 50:50 mixture of oleyl alcohol:octanol or oleyl alcohol. Rapid removal of sulfuric acid, 5-hydroxymethyl and furfural was observed. The rate of acetic acid removal decreased as the pH of the hydrolysate increased. Regeneration of the organic extractant was achieved by back extraction into an aqueous phase containing NaOH and ethanol. A cleaning protocol consisting of flushing the hydrolysate compartment with NaOH and the organic phase compartment with pure organic phase enabled regeneration and reuse of the module. Ethanol yields from hydrolysates detoxified by membrane extraction using 15% Alamine 336 in oleyl alcohol were about 10% higher than those from hydrolysates detoxified using ammonium hydroxide treatment.

  19. Membrane air-stripping: Effects of pretreatment

    SciTech Connect

    Castro, K. ); Zander, A.K. . Dept. of Civil and Environmental Engineering)

    1995-03-01

    As a result of the Safe Drinking Water Act and its 1986 amendments, the number of regulated volatile organic chemicals (VOCs) has increased substantially. The discovery of drinking water supply sources contaminated by VOCs is also increasing. These factors have led to the development of alternative treatment methods for control of VOCs. Microporous polypropylene hollow-fiber membranes offer significant advantages over packed-tower aeration for removing volatile organic chemicals. A laboratory study assessed the performance of membrane air-stripping in continuous operation, while exposed to various pretreatments. Results indicate that membrane air-stripping is compatible with low-pH or low-chlorine waters but not with waters of high pH or high-chlorine concentration or those that are ozonated.

  20. DNA sequencing using fluorescence background electroblotting membrane

    DOEpatents

    Caldwell, K.D.; Chu, T.J.; Pitt, W.G.

    1992-05-12

    A method for the multiplex sequencing on DNA is disclosed which comprises the electroblotting or specific base terminated DNA fragments, which have been resolved by gel electrophoresis, onto the surface of a neutral non-aromatic polymeric microporous membrane exhibiting low background fluorescence which has been surface modified to contain amino groups. Polypropylene membranes are preferably and the introduction of amino groups is accomplished by subjecting the membrane to radio or microwave frequency plasma discharge in the presence of an aminating agent, preferably ammonia. The membrane, containing physically adsorbed DNA fragments on its surface after the electroblotting, is then treated with crosslinking means such as UV radiation or a glutaraldehyde spray to chemically bind the DNA fragments to the membrane through amino groups contained on the surface. The DNA fragments chemically bound to the membrane are subjected to hybridization probing with a tagged probe specific to the sequence of the DNA fragments. The tagging may be by either fluorophores or radioisotopes. The tagged probes hybridized to the target DNA fragments are detected and read by laser induced fluorescence detection or autoradiograms. The use of aminated low fluorescent background membranes allows the use of fluorescent detection and reading even when the available amount of DNA to be sequenced is small. The DNA bound to the membranes may be reprobed numerous times. No Drawings

  1. Minicircle microporation-based non-viral gene delivery improved the targeting of mesenchymal stem cells to an injury site.

    PubMed

    Mun, Ji-Young; Shin, Keun Koo; Kwon, Ohsuk; Lim, Yong Taik; Oh, Doo-Byoung

    2016-09-01

    Genetic engineering approaches to improve the therapeutic potential of mesenchymal stem cells (MSCs) have been made by viral and non-viral gene delivery methods. Viral methods have severe limitations in clinical application because of potential oncogenic, pathogenic, and immunogenic risks, while non-viral methods have suffered from low transfection efficiency and transient weak expression as MSCs are hard-to-transfect cells. In this study, minicircle, which is a minimal expression vector free of bacterial sequences, was employed for MSC transfection as a non-viral gene delivery method. The conventional cationic liposome method was not effective for MSC transfection as it resulted in very low transfection efficiency (less than 5%). Microporation, a new electroporation method, greatly improved the transfection efficiency of minicircles by up to 66% in MSCs without any significant loss of cell viability. Furthermore, minicircle microporation generated much stronger and prolonged transgene expression compared with plasmid microporation. When MSCs microporated with minicircle harboring firefly luciferase gene were subcutaneously injected to mice, the bioluminescence continued for more than a week, whereas the bioluminescence of the MSCs induced by plasmid microporation rapidly decreased and disappeared in mice within three days. By minicircle microporation as a non-viral gene delivery, MSCs engineered to overexpress CXCR4 showed greatly increased homing ability toward an injury site as confirmed through in vivo bioluminescence imaging in mice. In summary, the engineering of MSCs through minicircle microporation is expected to enhance the therapeutic potential of MSCs in clinical applications. PMID:27315214

  2. Vaccination of sheep against haemonchosis with H11, a gut membrane-derived protective antigen from the adult parasite: prevention of the periparturient rise and colostral transfer of protective immunity.

    PubMed

    Andrews, S J; Hole, N J; Munn, E A; Rolph, T P

    1995-07-01

    Pregnant ewes were immunised with a fraction highly enriched in the membrane glycoprotein antigen H11, isolated from the intestinal brush border of adult Haemonchus contortus. Immunity induced by immunisation was able to abolish almost completely (98-99%) the worm egg output from pregnant ewes challenged with ca. 10,000 infective larvae of H. contortus during the last trimester. Furthermore, lambs born and reared on vaccinated ewes had substantial antibody levels to H11 derived from maternal transfer. This antibody conferred moderate protection against a bolus challenge of ca. 3000 infective larvae of H. contortus in 5-week-old lambs.

  3. Liquid membrane purification of biogas

    SciTech Connect

    Majumdar, S.; Guha, A.K.; Lee, Y.T.; Papadopoulos, T.; Khare, S. . Dept. of Chemistry and Chemical Engineering)

    1991-03-01

    Conventional gas purification technologies are highly energy intensive. They are not suitable for economic removal of CO{sub 2} from methane obtained in biogas due to the small scale of gas production. Membrane separation techniques on the other hand are ideally suited for low gas production rate applications due to their modular nature. Although liquid membranes possess a high species permeability and selectivity, they have not been used for industrial applications due to the problems of membrane stability, membrane flooding and poor operational flexibility, etc. A new hollow-fiber-contained liquid membrane (HFCLM) technique has been developed recently. This technique overcomes the shortcomings of the traditional immobilized liquid membrane technology. A new technique uses two sets of hydrophobic, microporous hollow fine fibers, packed tightly in a permeator shell. The inter-fiber space is filled with an aqueous liquid acting as the membrane. The feed gas mixture is separated by selective permeation of a species through the liquid from one fiber set to the other. The second fiber set carries a sweep stream, gas or liquid, or simply the permeated gas stream. The objectives (which were met) of the present investigation were as follows. To study the selective removal of CO{sub 2} from a model biogas mixture containing 40% CO{sub 2} (the rest being N{sub 2} or CH{sub 4}) using a HFCLM permeator under various operating modes that include sweep gas, sweep liquid, vacuum and conventional permeation; to develop a mathematical model for each mode of operation; to build a large-scale purification loop and large-scale permeators for model biogas separation and to show stable performance over a period of one month.

  4. Sorption of chlorophenols on microporous minerals: mechanism and influence of metal cations, solution pH, and humic acid.

    PubMed

    Yang, Hui; Hu, Yuanan; Cheng, Hefa

    2016-10-01

    Sorption of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) on a range of dealuminated zeolites were investigated to understand the mechanism of their sorption on microporous minerals, while the influence of common metal cations, solution pH, and humic acid was also studied. Sorption of chlorophenols was found to increase with the hydrophobicity of the sorbates and that of the microporous minerals, indicating the important role of hydrophobic interactions, while sorption was also stronger in the micropores of narrower sizes because of greater enhancement of the dispersion interactions. The presence of metal cations could enhance chlorophenol sorption due to the additional electrostatic attraction between metal cations exchanged into the mineral micropores and the chlorophenolates, and this effect was apparent on the mineral sorbent with a high density of surface cations (2.62 sites/nm(2)) in its micropores. Under circum-neutral or acidic conditions, neutral chlorophenol molecules adsorbed into the hydrophobic micropores through displacing the "loosely bound" water molecules, while their sorption was negligible under moderately alkaline conditions due to electrostatic repulsion between the negatively charged zeolite framework and anionic chlorophenolates. The influence of humic acid on sorption of chlorophenols on dealuminated Y zeolites suggests that its molecules did not block the micropores but created a secondary sorption sites by forming a "coating layer" on the external surface of the zeolites. These mechanistic insights could help better understand the interactions of ionizable chlorophenols and metal cations in mineral micropores and guide the selection and design of reusable microporous mineral sorbents for sorptive removal of chlorophenols from aqueous stream. PMID:27364487

  5. Sorption of chlorophenols on microporous minerals: mechanism and influence of metal cations, solution pH, and humic acid.

    PubMed

    Yang, Hui; Hu, Yuanan; Cheng, Hefa

    2016-10-01

    Sorption of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) on a range of dealuminated zeolites were investigated to understand the mechanism of their sorption on microporous minerals, while the influence of common metal cations, solution pH, and humic acid was also studied. Sorption of chlorophenols was found to increase with the hydrophobicity of the sorbates and that of the microporous minerals, indicating the important role of hydrophobic interactions, while sorption was also stronger in the micropores of narrower sizes because of greater enhancement of the dispersion interactions. The presence of metal cations could enhance chlorophenol sorption due to the additional electrostatic attraction between metal cations exchanged into the mineral micropores and the chlorophenolates, and this effect was apparent on the mineral sorbent with a high density of surface cations (2.62 sites/nm(2)) in its micropores. Under circum-neutral or acidic conditions, neutral chlorophenol molecules adsorbed into the hydrophobic micropores through displacing the "loosely bound" water molecules, while their sorption was negligible under moderately alkaline conditions due to electrostatic repulsion between the negatively charged zeolite framework and anionic chlorophenolates. The influence of humic acid on sorption of chlorophenols on dealuminated Y zeolites suggests that its molecules did not block the micropores but created a secondary sorption sites by forming a "coating layer" on the external surface of the zeolites. These mechanistic insights could help better understand the interactions of ionizable chlorophenols and metal cations in mineral micropores and guide the selection and design of reusable microporous mineral sorbents for sorptive removal of chlorophenols from aqueous stream.

  6. Semipermeable thin-film membranes comprising siloxane, alkoxysilyl and aryloxysilyl oligomers and copolymers

    DOEpatents

    Babcock, W.C.; Friesen, D.T.

    1988-11-01

    Novel semipermeable membranes and thin film composite (TFC) gas separation membranes useful in the separation of oxygen, nitrogen, hydrogen, water vapor, methane, carbon dioxide, hydrogen sulfide, lower hydrocarbons, and other gases are disclosed. The novel semipermeable membranes comprise the polycondensation reaction product of two complementary polyfunctional compounds, each having at least two functional groups that are mutually reactive in a condensation polymerization reaction, and at least one of which is selected from siloxanes, alkoxsilyls and aryloxysilyls. The TFC membrane comprises a microporous polymeric support, the surface of which has the novel semipermeable film formed thereon, preferably by interfacial polymerization.

  7. Semipermeable thin-film membranes comprising siloxane, alkoxysilyl and aryloxysilyl oligomers and copolymers

    DOEpatents

    Babcock, Walter C.; Friesen, Dwayne T.

    1988-01-01

    Novel semiperimeable membranes and thin film composite (TFC) gas separation membranes useful in the separation of oxygen, nitrogen, hydrogen, water vapor, methane, carbon dioxide, hydrogen sulfide, lower hydrocarbons, and other gases are disclosed. The novel semipermeable membranes comprise the polycondensation reaction product of two complementary polyfunctional compounds, each having at least two functional groups that are mutually reactive in a condensation polymerization reaction, and at least one of which is selected from siloxanes, alkoxsilyls and aryloxysilyls. The TFC membrane comprises a microporous polymeric support, the surface of which has the novel semipermeable film formed thereon, preferably by interfacial polymerization.

  8. Preparation and Char Characterization of Composite Membrane for High Temperature Gas Separation.

    SciTech Connect

    Illias, S.; King, F.G.

    1997-07-31

    A palladium-ceramic composite membrane was developed by electroless deposition of palladium on microporous ceramic substrate. By measuring the permeation characteristics of pure and mixed gases, it was found that the new membrane has a very high permeability and selectivity for hydrogen. During this reporting period, a concurrent flow model for a membrane module was developed to study the performance of palladium-ceramic composite membranes for hydrogen separation in terms of product purity under various operating conditions. The model neglects mass transfer resistance but it was found that the difference between the predicted and actual hydrogen composition was less than 12%.

  9. Preparation and characterization of composite membrane for high temperature gas separation

    SciTech Connect

    Ilias, S.; King, F.G.; Su, N.

    1994-10-01

    The objective of this project is to develop thin film palladium membranes for separation of hydrogen in high temperature applications. The authors plan to use electroless plating to deposit thin palladium films on microporous ceramic and silver substrates and then characterize the membrane in terms of permeability and selectivity for gas separation. To accomplish the research objective, the project requires three tasks: Development of a process for composite membrane fabrication; Characterization of composite membrane; and Development of theoretical model for hydrogen gas separation. The experimental procedures are described.

  10. Separation of Hydrogen Using an Electroless Deposited Thin-Film Palladium-Ceramic Composite Membrane

    SciTech Connect

    Ilias, S.; King, F.G.; Fan, Ting-Fang; Roy, S.

    1996-12-31

    The primary objective of this project was to prepare and characterize a hydrogen permselective palladium-ceramic composite membrane for high temperature gas separations and catalytic membrane reactors. Electroless plating method was used to deposit a thin palladium film on microporous ceramic substrate. The objective of this paper is to discuss the preparation and characterization of a thin-film palladium-ceramic composite membrane for selective separation of hydrogen at elevated temperatures and pressures. In this paper, we also present a model to describe the hydrogen transport through the palladium-ceramic composite membrane in a cocurrent flow configuration.

  11. A polystyrene-based microfluidic device with three-dimensional interconnected microporous walls for perfusion cell culture

    PubMed Central

    Chan, Chung Yu; Goral, Vasiliy N.; DeRosa, Michael E.; Huang, Tony Jun

    2014-01-01

    In this article, we present a simple, rapid prototyped polystyrene-based microfluidic device with three-dimensional (3D) interconnected microporous walls for long term perfusion cell culture. Patterned 3D interconnected microporous structures were created by a chemical treatment together with a protective mask and the native hydrophobic nature of the microporous structures were selectively made hydrophilic using oxygen plasma treatment together with a protective mask. Using this polystyrene-based cell culture microfluidic device, we successfully demonstrated the support of four days perfusion cell culture of hepatocytes (C3A cells). PMID:25379110

  12. 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.

  13. Gas separation by composite solvent-swollen membranes

    DOEpatents

    Matson, S.L.; Lee, E.K.L.; Friesen, D.T.; Kelly, D.J.

    1989-04-25

    There is disclosed a composite immobilized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorus or sulfur atom, and having a boiling point of at least 100 C and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation. 3 figs.

  14. Gas separation by composite solvent-swollen membranes

    DOEpatents

    Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

    1989-01-01

    There is disclosed a composite immobulized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorous or sulfur atom, and having a boiling point of at least 100.degree. C. and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation.

  15. Membrane distillation employed for separation of water isotopic compounds

    SciTech Connect

    Chmielewski, A.G.; Zakrzewska-Trznadel, G.

    1995-04-01

    An attempt to apply membrane distillation (MD) for the enrichment of waste isotopic compounds was made. The process was conducted as a direct-contact MD with flat-sheet microporous, hydrophobic polytetrafluorethylene (PTFE) membranes in the temperature range 323-353K. The distillate condensation was carried out directly into a stream of cooling water. The comparison between calculated Rayleigh distillation curves and the results of permeation experiments demonstrated the MD process to be more efficient than simple distillation for enrichment of the heavy isotopes in water.

  16. REFORMING OF LIQUID HYDROCARBONS IN A NOVEL HYDROGEN-SELECTIVE MEMBRANE-BASED FUEL PROCESSOR

    SciTech Connect

    Shamsuddin Ilias

    2003-06-30

    We propose to develop an inorganic metal-metal composite membrane to study reforming of liquid hydrocarbons and methanol by equilibrium shift in membrane-reactor configuration, viewed as fuel processor. Based on our current understanding and experience in the Pd-ceramic composite membrane, we propose to further develop this membrane to a Pd and Pd-Ag alloy membrane on microporous stainless steel support to provide structural reliability from distortion due to thermal cycling. Because of the metal-metal composite structure, we believe that the associated end-seal problem in the Pd-ceramic composite membrane in tubular configuration would not be an issue at all. We plan to test this membrane as membrane-reactor-separator for reforming liquid hydrocarbons and methanol for simultaneous production and separation of high-purity hydrogen for PEM fuel cell applications. To improve the robustness of the membrane film and deep penetration into the pores, we have used osmotic pressure field in the electroless plating process. Using this novel method, we deposited thin Pd-film on the inside of microporous stainless steel tube and the deposited film appears to robust and defect free. Work is in progress to evaluate the hydrogen perm-selectivity of the Pd-stainless steel membrane.

  17. DNA sequencing using fluorescence background electroblotting membrane

    DOEpatents

    Caldwell, Karin D.; Chu, Tun-Jen; Pitt, William G.

    1992-01-01

    A method for the multiplex sequencing on DNA is disclosed which comprises the electroblotting or specific base terminated DNA fragments, which have been resolved by gel electrophoresis, onto the surface of a neutral non-aromatic polymeric microporous membrane exhibiting low background fluorescence which has been surface modified to contain amino groups. Polypropylene membranes are preferably and the introduction of amino groups is accomplished by subjecting the membrane to radio or microwave frequency plasma discharge in the presence of an aminating agent, preferably ammonia. The membrane, containing physically adsorbed DNA fragments on its surface after the electroblotting, is then treated with crosslinking means such as UV radiation or a glutaraldehyde spray to chemically bind the DNA fragments to the membrane through said smino groups contained on the surface thereof. The DNA fragments chemically bound to the membrane are subjected to hybridization probing with a tagged probe specific to the sequence of the DNA fragments. The tagging may be by either fluorophores or radioisotopes. The tagged probes hybridized to said target DNA fragments are detected and read by laser induced fluorescence detection or autoradiograms. The use of aminated low fluorescent background membranes allows the use of fluorescent detection and reading even when the available amount of DNA to be sequenced is small. The DNA bound to the membrances may be reprobed numerous times.

  18. Meso- and micropore characteristics of coal lithotypes: Implications for CO2 adsorption

    USGS Publications Warehouse

    Mastalerz, Maria; Drobniak, A.; Rupp, J.

    2008-01-01

    Lithotypes (vitrain, clarain, and fusain) of high volatile bituminous Pennsylvanian coals (Ro of 0.56-0.62%) from Indiana (the Illinois Basin) have been studied with regard to meso- and micropore characteristics using low-pressure nitrogen and carbon dioxide adsorption techniques, respectively. High-pressure CO2 adsorption isotherms were obtained from lithotypes of the Lower Block Coal Member (the Brazil Formation) and the Springfield Coal Member (the Petersburg Formation), and after evacuation of CO2, the lithotypes were re-analyzed for meso- and micropore characteristics to investigate changes related to high-pressure CO2 adsorption. Coal lithotypes have differing Brunauer-Emmett-Teller (BET) surface areas and mesopore volumes, with significantly lower values in fusains than in vitrains or clarains. Fusains have very limited pore volume in the pore size width of 4-10 nm, and the volume, increases with an increase in pore size, in contrast to vitrain, for which a 4-10 nm range is the dominant pore'Wlidth. For clarain, both pores of 4-10 nm and pores larger than 20 nm contribute substantially to the mesoporosity. Micropore surface areas are the smallest for fusain (from 72.8 to 98.2 m2/g), largest for vitrain (from 125.0 to,158.4 m2 /g), and intermediate for clarain (from 110.5 to 124.4 m2/g). Similar relationships are noted for micropore volumes, and the lower values of these parameters in fusains are related to smaller volumes of all incremental micropore sizes. In the Springfield and the Lower Block Coal Members, among lithotypes studied, fusain has the lowest adsorption capacity. For the Lower Block, vitrain has significantly higher adsorption capacity than fusain and clarain, whereas for the Springfield, vitrain and clarain have comparable but still significantly higher adsorption capacities than fusain. The Lower Block vitrain and fusain have much higher adsorption capacities than those in the Springfield, whereas the clarains of the two coals are comparable

  19. Forward osmosis with a novel thin-film inorganic membrane.

    PubMed

    You, Shijie; Tang, Chuyang; Yu, Chen; Wang, Xiuheng; Zhang, Jinna; Han, Jia; Gan, Yang; Ren, Nanqi

    2013-08-01

    Forward osmosis (FO) represents a new promising membrane technology for liquid separation driven by the osmotic pressure of aqueous solution. Organic polymeric FO membranes are subject to severe internal concentration polarization due to asymmetric membrane structure, and low stability due to inherent chemical composition. To address these limitations, this study focuses on the development of a new kind of thin-film inorganic (TFI) membrane made of microporous silica xerogels immobilized onto a stainless steel mesh (SSM) substrate. The FO performances of the TFI membrane were evaluated upon a lab-scale cell-type FO reactor using deionized water as feed solution and sodium chloride (NaCl) as draw solution. The results demonstrated that the TFI membrane could achieve transmembrane water flux of 60.3 L m(-2) h(-1) driven by 2.0 mol L(-1) NaCl draw solution at ambient temperature. Meanwhile, its specific solute flux, i.e. the solute flux normalized by the water flux (0.19 g L(-1)), was 58.7% lower than that obained for a commercial cellulose triacetate (CTA) membrane (0.46 g L(-1)). The quasi-symmetry thin-film microporous structure of the silica membrane is responsible for low-level internal concentration polarization, and thus enhanced water flux during FO process. Moreover, the TFI membrne demonstrated a substantially improved stability in terms of mechanical strength, and resistance to thermal and chemical stimulation. This study not only provides a new method for fabricating quasi-symmetry thin-film inorganic silica membrane, but also suggests an effective strategy using this alternative membrane to achieve improved FO performances for scale-up applications. PMID:23829428

  20. A semiconducting microporous framework of Cd6Ag4(SPh)16 clusters interlinked using rigid and conjugated bipyridines.

    PubMed

    Xu, Chao; Hedin, Niklas; Shi, Hua-Tian; Zhang, Qian-Feng

    2014-04-11

    Ternary supertetrahedral chalcogenolate clusters were interlinked with bipyridines into a microporous semiconducting framework with properties qualitatively different from those of the original clusters. Both the framework and the clusters were effective photocatalysts, and rapidly degraded the dye rhodamine B.

  1. An Elastic Monolithic Catalyst: A Microporous Metalloporphyrin-Containing Framework-Wrapped Melamine Foam for Process-Intensified Acyl Transfer.

    PubMed

    Wu, Keyi; Guo, Jia; Wang, Changchun

    2016-05-10

    The advent of conjugated microporous polymers (CMPs) has had significant impact in catalysis. However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of CMPs in catalytic reactions. Herein, the preparation of a foam-supporting CMP composite with interconnective micropores and macropores and elastic properties is reported. Metalloporphyrin-based CMP organogels are synthesized within the melamine foam by a room-temperature oxidative homocoupling reaction of terminal alkynes. Upon drying, the CMP-based xerogels tightly wrap the framework skeletons of the foam, while the foam cells are still open to allow for the preservation of elasticity and macroporosity. Such a hierarchical structure is efficient for acyl transfer, facilitates substrate diffusion within interpenetrative macropores and micropores, and could be used to intensify catalytic processes.

  2. Polymer nanosieve membranes for CO2-capture applications

    NASA Astrophysics Data System (ADS)

    Du, Naiying; Park, Ho Bum; Robertson, Gilles P.; Dal-Cin, Mauro M.; Visser, Tymen; Scoles, Ludmila; Guiver, Michael D.

    2011-05-01

    Microporous organic polymers (MOPs) are of potential significance for gas storage, gas separation and low-dielectric applications. Among many approaches for obtaining such materials, solution-processable MOPs derived from rigid and contorted macromolecular structures are promising because of their excellent mass transport and mass exchange capability. Here we show a class of amorphous MOP, prepared by [2+3] cycloaddition modification of a polymer containing an aromatic nitrile group with an azide compound, showing super-permeable characteristics and outstanding CO2 separation performance, even under polymer plasticization conditions such as CO2/light gas mixtures. This unprecedented result arises from the introduction of tetrazole groups into highly microporous polymeric frameworks, leading to more favourable CO2 sorption with superior affinity in gas mixtures, and selective CO2 transport by presorbed CO2 molecules that limit access by other light gas molecules. This strategy provides a direction in the design of MOP membrane materials for economic CO2 capture processes.

  3. π-Conjugated Microporous Polymer Films: Designed Synthesis, Conducting Properties, and Photoenergy Conversions

    PubMed Central

    Gu, Cheng; Huang, Ning; Chen, Youchun; Qin, Leiqiang; Xu, Hong; Zhang, Shitong; Li, Fenghong; Ma, Yuguang; Jiang, Donglin

    2015-01-01

    Conjugated microporous polymers are a unique class of polymers that combine extended π-conjugation with inherent porosity. However, these polymers are synthesized through solution-phase reactions to yield insoluble and unprocessable solids, which preclude not only the evaluation of their conducting properties but also the fabrication of thin films for device implementation. Here, we report a strategy for the synthesis of thin films of π-conjugated microporous polymers by designing thiophene-based electropolymerization at the solution–electrode interface. High-quality films are prepared on a large area of various electrodes, the film thickness is controllable, and the films are used for device fabrication. These films are outstanding hole conductors and, upon incorporation of fullerenes into the pores, function as highly efficient photoactive layers for energy conversions. Our film strategy may boost the applications in photocatalysis, energy storage, and optoelectronics. PMID:26418672

  4. The Electrochemistry with Lithium versus Sodium of Selenium Confined To Slit Micropores in Carbon.

    PubMed

    Xin, Sen; Yu, Le; You, Ya; Cong, Huai-Ping; Yin, Ya-Xia; Du, Xue-Li; Guo, Yu-Guo; Yu, Shu-Hong; Cui, Yi; Goodenough, John B

    2016-07-13

    Substitution of selenium for sulfur in the cathode of a rechargeable battery containing Sx molecules in microporous slits in carbon allows a better characterization of the electrochemical reactions that occur. Paired with a metallic lithium anode, the Sex chains are converted to Li2Se in a single-step reaction. With a sodium anode, a sequential chemical reaction is characterized by a continuous chain shortening of Sex upon initial discharge before completing the reduction to Na2Se; on charge, the reconstituted Sex molecules retain a smaller x value than the original Sex chain molecule. In both cases, the Se molecules remain almost completely confined to the micropore slits to give a long cycle life. PMID:27347697

  5. Microporous carbon nanosheets with redox-active heteroatoms for pseudocapacitive charge storage

    NASA Astrophysics Data System (ADS)

    Yun, Y. S.; Kim, D.-H.; Hong, S. J.; Park, M. H.; Park, Y. W.; Kim, B. H.; Jin, H.-J.; Kang, K.

    2015-09-01

    We report microporous carbon nanosheets containing numerous redox active heteroatoms fabricated from exfoliated waste coffee grounds by simple heating with KOH for pseudocapacitive charge storage. We found that various heteroatom combinations in carbonaceous materials can be a redox host for lithium ion storage. The bio-inspired nanomaterials had unique characteristics, showing superior electrochemical performances as cathode for asymmetric pseudocapacitors.We report microporous carbon nanosheets containing numerous redox active heteroatoms fabricated from exfoliated waste coffee grounds by simple heating with KOH for pseudocapacitive charge storage. We found that various heteroatom combinations in carbonaceous materials can be a redox host for lithium ion storage. The bio-inspired nanomaterials had unique characteristics, showing superior electrochemical performances as cathode for asymmetric pseudocapacitors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04231c

  6. CO2 capture from humid flue gases and humid atmosphere using a microporous coppersilicate.

    PubMed

    Datta, Shuvo Jit; Khumnoon, Chutharat; Lee, Zhen Hao; Moon, Won Kyung; Docao, Son; Nguyen, Thanh Huu; Hwang, In Chul; Moon, Dohyun; Oleynikov, Peter; Terasaki, Osamu; Yoon, Kyung Byung

    2015-10-16

    Capturing CO2 from humid flue gases and atmosphere with porous materials remains costly because prior dehydration of the gases is required. A large number of microporous materials with physical adsorption capacity have been developed as CO2-capturing materials. However, most of them suffer from CO2 sorption capacity reduction or structure decomposition that is caused by co-adsorbed H2O when exposed to humid flue gases and atmosphere. We report a highly stable microporous coppersilicate. It has H2O-specific and CO2-specific adsorption sites but does not have H2O/CO2-sharing sites. Therefore, it readily adsorbs both H2O and CO2 from the humid flue gases and atmosphere, but the adsorbing H2O does not interfere with the adsorption of CO2. It is also highly stable after adsorption of H2O and CO2 because it was synthesized hydrothermally.

  7. Ordered microporous layered lanthanide 1,3,5-benzenetriphosphonates pillared with cationic organic molecules.

    PubMed

    Araki, Takahiro; Kondo, Atsushi; Maeda, Kazuyuki

    2015-04-13

    Novel isomorphous pillared-layer-type crystalline lanthanide 1,3,5-benzenetriphosphonates were prepared with bpy and dbo as organic pillars (LnBP-bpy and LnBP-dbo; Ln: Ce, Pr, and Nd). Ab initio crystal structure solution using synchrotron X-ray powder diffraction data revealed that the organic pillars do not exist as neutral coordinating ligands but as cationic molecules. Especially the LnBP-dbo phases have ordered interlayer space filled with water molecules between the dbo pillars, and the interlayer water is successfully removed by heating under vacuum with slightly distorted but basically retained pillared layer structures. Microporosity of the materials is confirmed by adsorption of nitrogen, carbon dioxide, and hydrogen gases. Such microporous layered metal phosphonates pillared with cationic molecules should be unprecedented and should offer new strategies to design ordered microporous materials.

  8. Effect of hydrophilic treatment of microporous layer on fuel cell performance

    SciTech Connect

    Mukundan, Rangachary; Davey, John R; Fairweather, Joseph D; Borup, Rodney L; Spernjak, Dusan; Spendelow, Jacob; Hussey, Daniel S; Jacobson, David L; Wilde, Peter; Schweiss, Ruediger

    2010-01-01

    The gas diffusion layer in a polymer electrolyte fuel cell is the component primarily responsible for effective water management under a wide variety of conditions. The incorporation of hydrophilic alumosilicate fibers in the microporous layer leads to an improvement in the fuel cell performance associated with a decrease in the mass transport resistance especially under high RH operation. This improvement in performance is obtained without sacrificing performance under low RH conditions. The alumosilicate fibers create domains that wick liquid water away from the catalyst layer. The improved mass transport performance is corroborated by AC impedance and neutron radiography analysis and is consistent with an increase in the average pore diameter inside the microporous layer.

  9. Use of a new microporous insulation in a sub car at Acme Steel

    SciTech Connect

    Harvey, H.; Gamble, F.C.; MacKenzie, I.B.

    1996-12-31

    Acme Steel Co. is a small integrated steel company headquartered in Riverdale IL., with its blast furnace and coke plant operations located in the city of Chicago. Rail transportation between the two plants is by Conrail with two crews assigned exclusively to Acme. The torpedo cars used for this service are specially reinforced, with 36 in. wheels and additional braking capability for safety on public rail tracks. Over a seven month period, microporous insulating panels 0.28 in. thick in No. 49 sub ladle saved an average 24 degrees in the iron on arrival at the BOF compared to the average for the rest of the fleet. The microporous insulation replaced 0.25 in. of compressed fiber panel.

  10. Microporous structure with layered interstitial surface treatment, and method and apparatus for preparation thereof

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1992-01-01

    A microporous structure with layered interstitial surface treatments, and the method and apparatus for its preparation are disclosed. The structure is prepared by sequentially subjecting a uniformly surface treated structure to atomic oxygen treatment to remove an outer layer of surface treatment to a generally uniform depth, and then surface treating the so exposed layer with another surface treating agent. The atomic oxygen/surface treatment steps may optionally be repeated, each successive time to a lesser depth, to produce a microporous structure having multilayered surface treatments. The apparatus employs at least one side arm from a main oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

  11. Microporous structure with layered interstitial surface treatment, and method and apparatus for preparation thereof

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1994-01-01

    A microporous structure with layered interstitial surface treatments, and method and apparatus for preparation thereof is presented. The structure is prepared by sequentially subjecting a uniformly surface-treated structure to atomic oxygen treatment to remove an outer layer of surface treatment to a generally uniform depth, and then surface treating the so exposed layer with another surface treating agent. The atomic oxygen/surface treatment steps may optionally be repeated, each successive time to a lesser depth, to produce a microporous structure having multilayered surface treatments. The apparatus employs at least one side arm from a main atomic oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

  12. The Electrochemistry with Lithium versus Sodium of Selenium Confined To Slit Micropores in Carbon.

    PubMed

    Xin, Sen; Yu, Le; You, Ya; Cong, Huai-Ping; Yin, Ya-Xia; Du, Xue-Li; Guo, Yu-Guo; Yu, Shu-Hong; Cui, Yi; Goodenough, John B

    2016-07-13

    Substitution of selenium for sulfur in the cathode of a rechargeable battery containing Sx molecules in microporous slits in carbon allows a better characterization of the electrochemical reactions that occur. Paired with a metallic lithium anode, the Sex chains are converted to Li2Se in a single-step reaction. With a sodium anode, a sequential chemical reaction is characterized by a continuous chain shortening of Sex upon initial discharge before completing the reduction to Na2Se; on charge, the reconstituted Sex molecules retain a smaller x value than the original Sex chain molecule. In both cases, the Se molecules remain almost completely confined to the micropore slits to give a long cycle life.

  13. A Luminescent Hypercrosslinked Conjugated Microporous Polymer for Efficient Removal and Detection of Mercury Ions.

    PubMed

    Xiang, Lu; Zhu, Yunlong; Gu, Shuai; Chen, Dongyang; Fu, Xian; Zhang, Yindong; Yu, Guipeng; Pan, Chunyue; Hu, Yuehua

    2015-09-01

    A hypercrosslinked conjugated microporous polymer (HCMP-1) with a robustly efficient absorption and highly specific sensitivity to mercury ions (Hg(2+)) is synthesized in a one-step Friedel-Crafts alkylation of cost-effective 2,4,6-trichloro-1,3,5-triazine and dibenzofuran in 1,2-dichloroethane. HCMP-1 has a moderate Brunauer-Emmett-Teller specific surface (432 m(2) g(-1)), but it displays a high adsorption affinity (604 mg g(-1)) and excellent trace efficiency for Hg(2+). The π-π* electronic transition among the aromatic heterocyclic rings endows HCMP-1 a strong fluorescent property and the fluorescence is obviously weakened after Hg(2+) uptake, which makes the hypercrosslinked conjugated microporous polymer a promising fluorescent probe for Hg(2+) detection, owning a super-high sensitivity (detection limit 5 × 10(-8) mol L(-1)). PMID:26088466

  14. Hybrid Ultra-Microporous Materials for Selective Xenon Adsorption and Separation.

    PubMed

    Mohamed, Mona H; Elsaidi, Sameh K; Pham, Tony; Forrest, Katherine A; Schaef, Herbert T; Hogan, Adam; Wojtas, Lukasz; Xu, Wenqian; Space, Brian; Zaworotko, Michael J; Thallapally, Praveen K

    2016-07-11

    The demand for Xe/Kr separation continues to grow due to the industrial significance of high-purity Xe gas. Current separation processes rely on energy intensive cryogenic distillation. Therefore, less energy intensive alternatives, such as physisorptive separation, using porous materials, are required. Herein we show that an underexplored class of porous materials called hybrid ultra-microporous materials (HUMs) affords new benchmark selectivity for Xe separation from Xe/Kr mixtures. The isostructural materials, CROFOUR-1-Ni and CROFOUR-2-Ni, are coordination networks that have coordinatively saturated metal centers and two distinct types of micropores, one of which is lined by CrO4 (2-) (CROFOUR) anions and the other is decorated by the functionalized organic linker. These nets offer unprecedented selectivity towards Xe. Modelling indicates that the selectivity of these nets is tailored by synergy between the pore size and the strong electrostatics afforded by the CrO4 (2-) anions. PMID:27238977

  15. Synthesis and characterization of functional thienyl-phosphine microporous polymers for carbon dioxide capture.

    PubMed

    Chen, Xianghui; Qiao, Shanlin; Du, Zhengkun; Zhou, Yuanhang; Yang, Renqiang

    2013-07-25

    A novel kind of functional organic microporous polymer is designed by introducing polar organic groups (P=O and P=S) and electron-rich heterocyclic into the framework to obtain high carbon dioxide capture capacity. The estimated Brunauer-Emmett-Teller (BET) surface areas of these polymers are about 600 m(2) g(-1) and the highest CO2 uptake is 2.26 mmol g(-1) (1.0 bar/273 K). Interestingly, the polymer containing P=O groups shows greater CO2 capture capacity than that containing P=S groups at the same temperature. In addition, these polymers show high isosteric heats of CO2 adsorption (28.6 kJ mol(-1) ), which can be competitive with some nitrogen-rich networks. Therefore, these microporous polymers are promising candidates for carbon dioxide capture.

  16. Electron transfer reactions in microporous solids. Progress report, September 1990--January 1993

    SciTech Connect

    Mallouk, T.E.

    1993-01-01

    Basic thrust the research program involves use of microporous solids (zeolites, clays, layered and tunnel structure oxide semiconductors) as organizing media for artificial photosynthetic systems. Purpose of the microporous solid is twofold. First, it induces spatial organization of photoactive and electroactive components (sensitizers, semiconductor particles, electron relays, and catalysts) at the solid-solution interface, enhancing the quantum efficiency of charge separation and separating physically the ultimate electron donor and acceptor in the electron transport chain. Second, since the microcrystalline solid admits only molecules of a certain charge and size, it is possible to achieve permanent charge separation by sieving chemical photoproducts (e.g., H{sub 2} and I{sub 3}{sup {minus}}, or H{sub 2} and O{sub 2)} from each other. Spectroscopic and electrochemical methods are used to study the kinetics of electron transfer reactions in these hybrid molecular/solid state assemblies.

  17. Tadalafil inclusion in microporous silica as effective dissolution enhancer: optimization of loading procedure and molecular state characterization.

    PubMed

    Mehanna, Mohammed M; Motawaa, Adel M; Samaha, Magda W

    2011-05-01

    Tadalafil is an efficient drug used to treat erectile dysfunction characterized by poor water solubility, which has a negative influence on its bioavailability. Utilization of microporous silica represents an effective and facile technology to increase the dissolution rate of poorly soluble drugs. Our strategy involved directly introducing tadalafil as guest molecule into microporous silica as host material by incipient wetness impregnation method. To optimize tadalafil inclusion, response surface methodology (RSM) using 3(3) factorial design was utilized. Furthermore, to investigate the molecular state of tadalafil, Fourier-transform infrared spectroscopy, differential scanning calorimetery, thermal gravimetrical analysis, nitrogen adsorption, and powder X-ray diffraction (PXRD) were carried out. The results obtained pointed out that the quantity of microporous silica was the predominant factor that increased the loading efficiency. For the optimized formula, the loading efficiency was 42.50 wt %. Adsorption-desorption experiments indicated that tadalafil has been introduced into the micropores. Powder XRD and differential scanning calorimetry analyses revealed that tadalafil is arranged in amorphous form. In addition, the dissolution rate of tadalafil from the microporous silica was faster than that of free drug. Amorphous tadalafil occluded in microporous silica did not crystallize over 3 months. These findings contributed in opening a new strategy concerning the utilization of porous silica for the dissolution rate enhancement. PMID:21374616

  18. A Perylene-Based Microporous Coordination Polymer Interacts Selectively with Electron-Poor Aromatics.

    PubMed

    Tran, Ly D; Ma, Jialiu; Wong-Foy, Antek G; Matzger, Adam J

    2016-04-11

    The design, synthesis, and properties of the new microporous coordination polymer UMCM-310 are described. The unique electronic character of the perylene-based linker enables selective interaction with electron-poor aromatics leading to efficient separation of nitroaromatics. UMCM-310 possesses high surface area and large pore size and thus permits the separation of large organic molecules based on adsorption rather than size exclusion.

  19. Conjugated microporous polymers with dimensionality-controlled heterostructures for green energy devices.

    PubMed

    Zhuang, Xiaodong; Gehrig, Dominik; Forler, Nina; Liang, Haiwei; Wagner, Manfred; Hansen, Michael Ryan; Laquai, Frédéric; Zhang, Fan; Feng, Xinliang

    2015-07-01

    Dimensionality for conjugated micro-porous polymers (CMP-nD, n = 0, 1, 2) is proven to be of great importance for tailoring their photophysical properties. Moreover, CMP-nD can further be converted into boron and nitrogen co-doped porous carbons (nDBN, n = 0, 1, 2) with maintained 0D, 1D, and 2D nano-structures and highly efficient catalytic performance.

  20. Fluorinated microporous organic polymers: design and applications in CO₂ adsorption and conversion.

    PubMed

    Yang, Zhen-Zhen; Zhao, Yanfei; Zhang, Hongye; Yu, Bo; Ma, Zhishuang; Ji, Guipeng; Liu, Zhimin

    2014-11-21

    Fluorinated microporous organic polymers (F-MOPs) were designed, showing twice higher CO2 adsorption capacity than corresponding non-fluorous MOPs. The incorporation of phenanthroline moieties into F-MOPs afforded them the ability to coordinate with Ag(I), and the resultant F-MOP-Ag(I) displayed high efficiency for the reaction of CO2 with propargyl alcohols to form α-alkylidene cyclic carbonates at 25 °C.

  1. The first route to highly stable crystalline microporous zirconium phosphonate metal-organic frameworks.

    PubMed

    Taddei, Marco; Costantino, Ferdinando; Marmottini, Fabio; Comotti, Angiolina; Sozzani, Piero; Vivani, Riccardo

    2014-12-01

    The first crystalline microporous zirconium phosphonate metal-organic framework (UPG-1) was synthesized using the novel tritopic ligand 2,4,6-tris(4-(phosphonomethyl)phenyl)-1,3,5-triazine. Its crystal structure was solved ab initio from laboratory powder X-ray diffraction data. UPG-1 displays remarkable thermal stability and hydrolysis resistance and has a good absorption affinity towards n-butane and CO2.

  2. Synthesis and gas adsorption properties of tetra-armed microporous organic polymer networks based on triphenylamine.

    PubMed

    Yang, Xiao; Yao, Shuwen; Yu, Miao; Jiang, Jia-Xing

    2014-04-01

    Two novel tetra-armed microporous organic polymers have been designed and synthesized via a nickel-catalyzed Yamamoto-type Ullmann cross-coupling reaction or Suzuki cross-coupling polycondensation. These polymers are stable in various solvents, including concentrated hydrochloric acid, and are thermally stable. The homocoupled polymer YPTPA shows much higher Brunauer-Emmet-Teller-specific surface area up to 1557 m(2) g(-1) than the copolymer SPTPA (544 m(2) g(-1)), and a high CO2 uptake ability of 3.03 mmol g(-1) (1.13 bar/273 K) with a CO2 /N2 sorption selectivity of 17.3:1. Both polymers show high isosteric heats of CO2 adsorption (22.7-26.5 kJ mol(-1)) because the incorporation of nitrogen atoms into the skeleton of microporous organic polymers enhances the interaction between the pore wall and the CO2 molecules. The values are higher than those of the porous aromatic frameworks, which contain neither additional polar functional groups nor nitrogen atoms, and are rather close to those of previously reported microporous organic polymers containing the nitrogen atoms on the pore wall. These data show that these materials would be potential candidates for applications in post-combustion CO2 capture and sequestration technology.

  3. A single-ligand ultra-microporous MOF for precombustion CO2 capture and hydrogen purification

    PubMed Central

    Nandi, Shyamapada; De Luna, Phil; Daff, Thomas D.; Rother, Jens; Liu, Ming; Buchanan, William; Hawari, Ayman I.; Woo, Tom K.; Vaidhyanathan, Ramanathan

    2015-01-01

    Metal organic frameworks (MOFs) built from a single small ligand typically have high stability, are rigid, and have syntheses that are often simple and easily scalable. However, they are normally ultra-microporous and do not have large surface areas amenable to gas separation applications. We report an ultra-microporous (3.5 and 4.8 Å pores) Ni-(4-pyridylcarboxylate)2 with a cubic framework that exhibits exceptionally high CO2/H2 selectivities (285 for 20:80 and 230 for 40:60 mixtures at 10 bar, 40°C) and working capacities (3.95 mmol/g), making it suitable for hydrogen purification under typical precombustion CO2 capture conditions (1- to 10-bar pressure swing). It exhibits facile CO2 adsorption-desorption cycling and has CO2 self-diffusivities of ~3 × 10−9 m2/s, which is two orders higher than that of zeolite 13X and comparable to other top-performing MOFs for this application. Simulations reveal a high density of binding sites that allow for favorable CO2-CO2 interactions and large cooperative binding energies. Ultra-micropores generated by a small ligand ensures hydrolytic, hydrostatic stabilities, shelf life, and stability toward humid gas streams. PMID:26824055

  4. Capture and conversion of CO2 at ambient conditions by a conjugated microporous polymer

    PubMed Central

    Xie, Yong; Wang, Ting-Ting; Liu, Xiao-Huan; Zou, Kun; Deng, Wei-Qiao

    2013-01-01

    Conjugated microporous polymers are a new class of porous materials with an extended π-conjugation in an amorphous organic framework. Owing to the wide-ranging flexibility in the choice and design of components and the available control of pore parameters, these polymers can be tailored for use in various applications, such as gas storage, electronics and catalysis. Here we report a class of cobalt/aluminium-coordinated conjugated microporous polymers that exhibit outstanding CO2 capture and conversion performance at atmospheric pressure and room temperature. These polymers can store CO2 with adsorption capacities comparable to metal-organic frameworks. The cobalt-coordinated conjugated microporous polymers can also simultaneously function as heterogeneous catalysts for the reaction of CO2 and propylene oxide at atmospheric pressure and room temperature, wherein the polymers demonstrate better efficiency than a homogeneous salen-cobalt catalyst. By combining the functions of gas storage and catalysts, this strategy provides a direction for cost-effective CO2 reduction processes. PMID:23727768

  5. Phenomena affecting morphology of microporous poly(acrylonitrile) prepared via phase separation from solution

    SciTech Connect

    Legasse, R.R.; Weagley, R.J.; Leslie, P.K.; Schneider, D.A.

    1990-01-01

    This paper is concerned with controlling the morphology of microporous polymers prepared via thermal demixing of solutions. 2 wt % solutions of poly(acrylonitrile) in maleic anhydride, a poor solvent, are first cooled to produce separated polymer-rich and solvent-rich phases. Removing the solvent by freeze drying then produces a microporous material having a density of 33 mg/cm{sup 3}, a void fraction of 97%, and a pore size of about 10 {mu}m. We find that the morphology cannot be explained by existing models, which focus on phase diagrams and kinetics of phase transformations during cooling of the solution. In conflict with those models, we find that two radically different morphologies can be produced even when the polymer concentration and cooling path are held strictly constant. A hypothesis that polymer degradation causes the different morphologies is not supported by GPC, {sup 13}C NMR, and FTIR experiments. Instead, we offer evidence that the different microporous morphologies are caused by different polymer conformations in solutions having the same concentration and temperature. 11 refs., 3 figs.

  6. A single-ligand ultra-microporous MOF for precombustion CO2 capture and hydrogen purification.

    PubMed

    Nandi, Shyamapada; De Luna, Phil; Daff, Thomas D; Rother, Jens; Liu, Ming; Buchanan, William; Hawari, Ayman I; Woo, Tom K; Vaidhyanathan, Ramanathan

    2015-12-01

    Metal organic frameworks (MOFs) built from a single small ligand typically have high stability, are rigid, and have syntheses that are often simple and easily scalable. However, they are normally ultra-microporous and do not have large surface areas amenable to gas separation applications. We report an ultra-microporous (3.5 and 4.8 Å pores) Ni-(4-pyridylcarboxylate)2 with a cubic framework that exhibits exceptionally high CO2/H2 selectivities (285 for 20:80 and 230 for 40:60 mixtures at 10 bar, 40°C) and working capacities (3.95 mmol/g), making it suitable for hydrogen purification under typical precombustion CO2 capture conditions (1- to 10-bar pressure swing). It exhibits facile CO2 adsorption-desorption cycling and has CO2 self-diffusivities of ~3 × 10(-9) m(2)/s, which is two orders higher than that of zeolite 13X and comparable to other top-performing MOFs for this application. Simulations reveal a high density of binding sites that allow for favorable CO2-CO2 interactions and large cooperative binding energies. Ultra-micropores generated by a small ligand ensures hydrolytic, hydrostatic stabilities, shelf life, and stability toward humid gas streams. PMID:26824055

  7. Highly sensitive gas-phase explosive detection by luminescent microporous polymer networks

    PubMed Central

    Räupke, André; Palma-Cando, Alex; Shkura, Eugen; Teckhausen, Peter; Polywka, Andreas; Görrn, Patrick; Scherf, Ullrich; Riedl, Thomas

    2016-01-01

    We propose microporous networks (MPNs) of a light emitting spiro-carbazole based polymer (PSpCz) as luminescent sensor for nitro-aromatic compounds. The MPNs used in this study can be easily synthesized on arbitrarily sized/shaped substrates by simple and low-cost electrochemical deposition. The resulting MPN afford an extremely high specific surface area of 1300 m2/g, more than three orders of magnitude higher than that of the thin films of the respective monomer. We demonstrate, that the luminescence of PSpCz is selectively quenched by nitro-aromatic analytes, e.g. nitrobenzene, 2,4-DNT and TNT. In striking contrast to a control sample based on non-porous spiro-carbazole, which does not show any luminescence quenching upon exposure to TNT at levels of 3 ppm and below, the microporous PSpCz shows a clearly detectable response even at TNT concentrations as low as 5 ppb, clearly demonstrating the advantage of microporous films as luminescent sensors for traces of explosive analytes. This level states the vapor pressure of TNT at room temperature. PMID:27373905

  8. CO2 Capture in the Sustainable Wheat-Derived Activated Microporous Carbon Compartments

    NASA Astrophysics Data System (ADS)

    Hong, Seok-Min; Jang, Eunji; Dysart, Arthur D.; Pol, Vilas G.; Lee, Ki Bong

    2016-10-01

    Microporous carbon compartments (MCCs) were developed via controlled carbonization of wheat flour producing large cavities that allow CO2 gas molecules to access micropores and adsorb effectively. KOH activation of MCCs was conducted at 700 °C with varying mass ratios of KOH/C ranging from 1 to 5, and the effects of activation conditions on the prepared carbon materials in terms of the characteristics and behavior of CO2 adsorption were investigated. Textural properties, such as specific surface area and total pore volume, linearly increased with the KOH/C ratio, attributed to the development of pores and enlargement of pores within carbon. The highest CO2 adsorption capacities of 5.70 mol kg‑1 at 0 °C and 3.48 mol kg‑1 at 25 °C were obtained for MCC activated with a KOH/C ratio of 3 (MCC-K3). In addition, CO2 adsorption uptake was significantly dependent on the volume of narrow micropores with a pore size of less than 0.8 nm rather than the volume of larger pores or surface area. MCC-K3 also exhibited excellent cyclic stability, facile regeneration, and rapid adsorption kinetics. As compared to the pseudo-first-order model, the pseudo-second-order kinetic model described the experimental adsorption data methodically.

  9. Highly sensitive gas-phase explosive detection by luminescent microporous polymer networks

    NASA Astrophysics Data System (ADS)

    Räupke, André; Palma-Cando, Alex; Shkura, Eugen; Teckhausen, Peter; Polywka, Andreas; Görrn, Patrick; Scherf, Ullrich; Riedl, Thomas

    2016-07-01

    We propose microporous networks (MPNs) of a light emitting spiro-carbazole based polymer (PSpCz) as luminescent sensor for nitro-aromatic compounds. The MPNs used in this study can be easily synthesized on arbitrarily sized/shaped substrates by simple and low-cost electrochemical deposition. The resulting MPN afford an extremely high specific surface area of 1300 m2/g, more than three orders of magnitude higher than that of the thin films of the respective monomer. We demonstrate, that the luminescence of PSpCz is selectively quenched by nitro-aromatic analytes, e.g. nitrobenzene, 2,4-DNT and TNT. In striking contrast to a control sample based on non-porous spiro-carbazole, which does not show any luminescence quenching upon exposure to TNT at levels of 3 ppm and below, the microporous PSpCz shows a clearly detectable response even at TNT concentrations as low as 5 ppb, clearly demonstrating the advantage of microporous films as luminescent sensors for traces of explosive analytes. This level states the vapor pressure of TNT at room temperature.

  10. Highly sensitive gas-phase explosive detection by luminescent microporous polymer networks.

    PubMed

    Räupke, André; Palma-Cando, Alex; Shkura, Eugen; Teckhausen, Peter; Polywka, Andreas; Görrn, Patrick; Scherf, Ullrich; Riedl, Thomas

    2016-01-01

    We propose microporous networks (MPNs) of a light emitting spiro-carbazole based polymer (PSpCz) as luminescent sensor for nitro-aromatic compounds. The MPNs used in this study can be easily synthesized on arbitrarily sized/shaped substrates by simple and low-cost electrochemical deposition. The resulting MPN afford an extremely high specific surface area of 1300 m(2)/g, more than three orders of magnitude higher than that of the thin films of the respective monomer. We demonstrate, that the luminescence of PSpCz is selectively quenched by nitro-aromatic analytes, e.g. nitrobenzene, 2,4-DNT and TNT. In striking contrast to a control sample based on non-porous spiro-carbazole, which does not show any luminescence quenching upon exposure to TNT at levels of 3 ppm and below, the microporous PSpCz shows a clearly detectable response even at TNT concentrations as low as 5 ppb, clearly demonstrating the advantage of microporous films as luminescent sensors for traces of explosive analytes. This level states the vapor pressure of TNT at room temperature. PMID:27373905

  11. Adsorption of pharmaceuticals to microporous activated carbon treated with potassium hydroxide, carbon dioxide, and steam.

    PubMed

    Fu, Heyun; Yang, Liuyan; Wan, Yuqiu; Xu, Zhaoyi; Zhu, Dongqiang

    2011-01-01

    Adsorption of sulfapyridine, tetracycline, and tylosin to a commercial microporous activated carbon (AC) and its potassium hydroxide (KOH)-, CO-, and steam-treated counterparts (prepared by heating at 850°C) was studied to explore efficient adsorbents for the removal of selected pharmaceuticals from water. Phenol and nitrobenzene were included as additional adsorbates, and nonporous graphite was included as a model adsorbent. The activation treatments markedly increased the specific surface area and enlarged the pore sizes of the mesopores of AC (with the strongest effects shown on the KOH-treated AC). Adsorption of large-size tetracycline and tylosin was greatly enhanced, especially for the KOH-treated AC (more than one order of magnitude), probably due to the alleviated size-exclusion effect. However, the treatments had little effect on adsorption of low-size phenol and nitrobenzene due to the predominance of micropore-filling effect in adsorption and the nearly unaffected content of small micropores causative to such effect. These hypothesized mechanisms on pore-size dependent adsorption were further tested by comparing surface area-normalized adsorption data and adsorbent pore size distributions with and without the presence of adsorbed antibiotics. The findings indicate that efficient adsorption of bulky pharmaceuticals to AC can be achieved by enlarging the adsorbent pore size through suitable activation treatments.

  12. CO2 Capture in the Sustainable Wheat-Derived Activated Microporous Carbon Compartments

    PubMed Central

    Hong, Seok-Min; Jang, Eunji; Dysart, Arthur D.; Pol, Vilas G.; Lee, Ki Bong

    2016-01-01

    Microporous carbon compartments (MCCs) were developed via controlled carbonization of wheat flour producing large cavities that allow CO2 gas molecules to access micropores and adsorb effectively. KOH activation of MCCs was conducted at 700 °C with varying mass ratios of KOH/C ranging from 1 to 5, and the effects of activation conditions on the prepared carbon materials in terms of the characteristics and behavior of CO2 adsorption were investigated. Textural properties, such as specific surface area and total pore volume, linearly increased with the KOH/C ratio, attributed to the development of pores and enlargement of pores within carbon. The highest CO2 adsorption capacities of 5.70 mol kg−1 at 0 °C and 3.48 mol kg−1 at 25 °C were obtained for MCC activated with a KOH/C ratio of 3 (MCC-K3). In addition, CO2 adsorption uptake was significantly dependent on the volume of narrow micropores with a pore size of less than 0.8 nm rather than the volume of larger pores or surface area. MCC-K3 also exhibited excellent cyclic stability, facile regeneration, and rapid adsorption kinetics. As compared to the pseudo-first-order model, the pseudo-second-order kinetic model described the experimental adsorption data methodically. PMID:27698448

  13. The Importance of Ion Packing on the Dynamics of Ionic Liquids during Micropore Charging

    SciTech Connect

    He, Yadong; Qiao, Rui; Vatamanu, Jenel; Borodin, Oleg; Bedrov, Dmitry; Huang, Jingsong; Sumpter, Bobby G.

    2015-12-07

    There is an emerging concern that using room-temperature ionic liquids (RTILs) together with microporous electrodes may compromise supercapacitors power density in spite of their benefit for enhancing energy density due to possibly slow transport of ions inside narrow pores. Based on molecular simulations of the diffusion of EMIM+ and TFSI ions in slit-shaped micropores (width < 2 nm,) under conditions similar to those during pore charging, we show that, in pores that accommodate only a single layer of ions, the ions diffuse increasingly faster as the pore becomes charged, even faster than Na^+ ions in bulk water. However, this trend can be reversed when the pore becomes highly charged. In pores wide enough to fit more than one layer of ions, the ion diffusion is typically slower than in the bulk, and only changes modestly as the pore becomes charged. Analysis of these results revealed that the fast (or slow) diffusion of ions inside a micropore is correlated most strongly with the dense (or loose) ion packing inside the pore during charging. The molecular details of ions and the precise width of pores modify these trends relatively weakly, except when the pore size is so narrow that the conformation of ions is strongly constrained by the pore walls. Insight from these results should be useful for establishing guidelines for the design of RTILs and porous electrode materials for supercapacitors.

  14. The Importance of Ion Packing on the Dynamics of Ionic Liquids during Micropore Charging

    DOE PAGES

    He, Yadong; Qiao, Rui; Vatamanu, Jenel; Borodin, Oleg; Bedrov, Dmitry; Huang, Jingsong; Sumpter, Bobby G.

    2015-12-07

    There is an emerging concern that using room-temperature ionic liquids (RTILs) together with microporous electrodes may compromise supercapacitors power density in spite of their benefit for enhancing energy density due to possibly slow transport of ions inside narrow pores. Based on molecular simulations of the diffusion of EMIM+ and TFSI ions in slit-shaped micropores (width < 2 nm,) under conditions similar to those during pore charging, we show that, in pores that accommodate only a single layer of ions, the ions diffuse increasingly faster as the pore becomes charged, even faster than Na^+ ions in bulk water. However, this trendmore » can be reversed when the pore becomes highly charged. In pores wide enough to fit more than one layer of ions, the ion diffusion is typically slower than in the bulk, and only changes modestly as the pore becomes charged. Analysis of these results revealed that the fast (or slow) diffusion of ions inside a micropore is correlated most strongly with the dense (or loose) ion packing inside the pore during charging. The molecular details of ions and the precise width of pores modify these trends relatively weakly, except when the pore size is so narrow that the conformation of ions is strongly constrained by the pore walls. Insight from these results should be useful for establishing guidelines for the design of RTILs and porous electrode materials for supercapacitors.« less

  15. Electrogenerated thin films of microporous polymer networks with remarkably increased electrochemical response to nitroaromatic analytes.

    PubMed

    Palma-Cando, Alex; Scherf, Ullrich

    2015-06-01

    Thin films of microporous polymer networks (MPNs) have been generated by electrochemical polymerization of a series of multifunctional carbazole-based monomers. The microporous films show high Brunauer-Emmett-Teller (BET) surface areas up to 1300 m2 g(-1) as directly measured by krypton sorption experiments. A correlation between the number of polymerizable carbazole units of the monomer and the resulting surface area is observed. Electrochemical sensing experiments with 1,3,5-trinitrobenzene as prototypical nitroaromatic analyte demonstrate an up to 180 times increased current response of MPN-modified glassy carbon electrodes in relation to the nonmodified electrode. The phenomenon probably involves intermolecular interactions between the electron-poor nitroaromatic analytes and the electron-rich, high surface area microporous deposits, with the electrochemical reduction at the MPN-modified electrodes being an adsorption-controlled process for low scan rates. We expect a high application potential of such MPN-modified electrodes for boosting the sensitivity of electrochemical sensor devices. PMID:25946727

  16. Capture and conversion of CO2 at ambient conditions by a conjugated microporous polymer.

    PubMed

    Xie, Yong; Wang, Ting-Ting; Liu, Xiao-Huan; Zou, Kun; Deng, Wei-Qiao

    2013-01-01

    Conjugated microporous polymers are a new class of porous materials with an extended π-conjugation in an amorphous organic framework. Owing to the wide-ranging flexibility in the choice and design of components and the available control of pore parameters, these polymers can be tailored for use in various applications, such as gas storage, electronics and catalysis. Here we report a class of cobalt/aluminium-coordinated conjugated microporous polymers that exhibit outstanding CO2 capture and conversion performance at atmospheric pressure and room temperature. These polymers can store CO2 with adsorption capacities comparable to metal-organic frameworks. The cobalt-coordinated conjugated microporous polymers can also simultaneously function as heterogeneous catalysts for the reaction of CO2 and propylene oxide at atmospheric pressure and room temperature, wherein the polymers demonstrate better efficiency than a homogeneous salen-cobalt catalyst. By combining the functions of gas storage and catalysts, this strategy provides a direction for cost-effective CO2 reduction processes.

  17. Development of high performance barrier membranes for enhanced protection and comfort

    NASA Astrophysics Data System (ADS)

    Tan, Kuitian

    New barrier membrane materials are needed to provide enhanced performance for occupations where resistance to harmful particles and liquid penetration is needed. Smaller pore sizes are necessary to provide the level of chemical and biological protection required for first responders, medical personnel, and chemical workers. These materials need to be comfortable while being liquid resistant and less accessible to harmful particles. To combine barrier property with high water vapor transmission rate (WVTR), a novel microporous polyurethane membrane that responds to moisture/liquid content was developed. The membrane surface was modified by graft polymerization with different molecular weights of poly(ethylene glycol) (PEG). The hydrophilicity of microporous polyurethane membranes was improved after surface modification with PEG. Both the surface pore sizes and the constricted part of through pore sizes of the bulk PU membranes were greatly reduced. Water vapor transmission rate (WVTR) measurements indicated that the pores of the modified PU membranes were responsive to the moisture content, and the membranes remain sufficient comfort after modification. An antimicrobial microporous polyurethane membrane was developed by grafting a moiety of 2,2,5,5-tetramethyl-imidozalidin-4-one (TMIO) hydantoin onto microporous polyurethane (PU) membrane substrate as an N-halamine precursor. When challenged by liquid suspension of microorganisms, TMIO modified PU membranes showed significant antibacterial properties against E. coli and S. aureus, with a total reduction achieved for both bacteria after a two-hour contact period. WVTR remained essentially unchanged after surface modification indicating that enhanced protection was achieved at no sacrifice of wearer comfort. Electrospun antimicrobial nanofibrous nylon 6 membranes were fabricated by incorporation of three structurally different N-halamine additives, chlorinated 5,5-dimethylhydantoin (CDMH), chlorinated 2

  18. Vacuum membrane distillation: Experiments and modeling

    SciTech Connect

    Bandini, S.; Saavedra, A.; Sarti, G.C.

    1997-02-01

    Vacuum membrane distillation is a membrane-based separation process considered here to remove volatile organic compounds from aqueous streams. Microporous hydrophobic membranes are used to separate the aqueous stream from a gas phase kept under vacuum. The evaporation of the liquid stream takes place on one side of the membrane, and mass transfer occurs through the vapor phase inside the membrane. The role of operative conditions on the process performance is widely investigated in the case of dilute binary aqueous mixtures containing acetone, ethanol, isopropanol, ethylacetate, methylacetate, or methylterbutyl ether. Temperature, composition, flow rate of the liquid feed, and pressure downstream the membrane are the main operative variables. Among these, the vacuum-side pressure is the major design factor since it greatly affects the separation efficiency. A mathematical model description of the process is developed, and the results are compared with the experiments. The model is finally used to predict the best operative conditions in which the process can work for the case of benzene removal from waste waters.

  19. 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.

  20. A dual-spatially-confined reservoir by packing micropores within dense graphene for long-life lithium/sulfur batteries

    NASA Astrophysics Data System (ADS)

    Li, Hongfei; Yang, Xiaowei; Wang, Xiaomin; He, Yu-Shi; Ye, Fangmin; Liu, Meinan; Zhang, Yuegang

    2016-01-01

    In lithium/sulfur batteries, micropores could bring about strong interactions with polysulfides, but could not alleviate the partial polysulfide overflowing outside because of the volume expansion of the lithiated sulfur. A dual-spatially-confined reservoir for sulfur by wrapping microporous carbon with dense graphene, micro@meso-porous DSC (dual-spatial carbon), is synthesized to solve this issue. Such a structure is prepared through two distinctive methods: graphene promoted in situ hydrothermal carbonization of organics to grow micropores on itself, and liquid mediated drying of graphene hydrogel to form mesoporous graphene frameworks. In contrast to previously reported hierarchical carbon/S, the inner micropores are mainly responsible for loading sulfur, which could help confine its particle size, thus increasing the electrical/ionic conductivity and the utilization of sulfur, and restrain lithium polysulfide dissolution because of strong interaction with pore walls; while the outer mesopores act as another reservoir to stabilize the overflowed polysulfide and to enhance the Li+ transport. The S-micro@meso-porous DSC cathode exhibits better discharge capacity and cycling performance than S-microporous AC and S-micro@macro-porous DSC, i.e., 59% and 37% higher capacity remaining at 0.5 C than the latter two, respectively.In lithium/sulfur batteries, micropores could bring about strong interactions with polysulfides, but could not alleviate the partial polysulfide overflowing outside because of the volume expansion of the lithiated sulfur. A dual-spatially-confined reservoir for sulfur by wrapping microporous carbon with dense graphene, micro@meso-porous DSC (dual-spatial carbon), is synthesized to solve this issue. Such a structure is prepared through two distinctive methods: graphene promoted in situ hydrothermal carbonization of organics to grow micropores on itself, and liquid mediated drying of graphene hydrogel to form mesoporous graphene frameworks. In

  1. Prospects for using membrane distallation for reprocessing liquid radioactive wastes

    SciTech Connect

    Dytnerskii, Y.I.; Karlin, Y.V.; Kropotov, B.N.

    1994-05-01

    Membrane distillation is a promising method for deep desalinization and for removal of impurities of different nature from water. The crux of the method is as follows. The initial (hot) solution, heated up to 30-70{degrees}C, is fed into one side of a hydrophobic microporous membrane. A less heated (cold) distillate moves along the other. Since the membrane is hydrophobic and the pores are small ({approximately}1 {mu}m and less), the liquid phase does not penetrate into the pores in accordance with Kelvin`s law. The vapor evaporating from the surface of the hot solution (the evaporation surface in this case are solution meniscuses forming at the entrance into a pore) penetrates into the pores of the membrane, diffuses through the air layer in the pore, and condenses on the surface of the menisci of cold liquid. In the process rarefaction is produced in the pores, and this accelerates evaporation and therefore increases its efficiency.

  2. Inorganic membranes for carbon capture and power generation

    NASA Astrophysics Data System (ADS)

    Snider, Matthew T.

    Inorganic membranes are under consideration for cost-effective reductions of carbon emissions from coal-fired power plants, both in the capture of pollutants post-firing and in the direct electrochemical conversion of coal-derived fuels for improved plant efficiency. The suitability of inorganic membrane materials for these purposes stems as much from thermal and chemical stability in coal plant operating conditions as from high performance in gas separations and power generation. Hydrophilic, micro-porous zeolite membrane structures are attractive for separating CO2 from N2 in gaseous waste streams due to the attraction of CO2 to the membrane surface and micropore walls that gives the advantage to CO2 transport. Recent studies have indicated that retention of the templating agent used in zeolite synthesis can further block N2 from the micropore interior and significantly improve CO2/N2 selectivity. However, the role of the templating agent in micro-porous transport has not been well investigated. In this work, gas sorption studies were conducted by high-pressure thermo-gravimetric analysis on Zeolite Y membrane materials to quantify the effect of the templating agent on CO2, N2, and H2O adsorption/desorption, as well as to examine the effect of humidification on overall membrane performance. In equilibrium conditions, the N2 sorption enthalpy was nearly unchanged by the presence of the templating agent, but the N2 pore occupation was reduced ˜1000x. Thus, the steric nature of the blocking of N2 from the micropores by the templating agent was confirmed. CO2 and H2O sorption enthalpies were similarly unaffected by the templating agent, and the micropore occupations were only reduced as much as the void volume taken up by the templating agent. Thus, the steric blocking effect did not occur for molecules more strongly attracted to the micropore walls. Additionally, in time-transient measurements the CO 2 and H2O mobilities were significantly enhanced by the presence

  3. Inorganic membranes for carbon capture and power generation

    NASA Astrophysics Data System (ADS)

    Snider, Matthew T.

    Inorganic membranes are under consideration for cost-effective reductions of carbon emissions from coal-fired power plants, both in the capture of pollutants post-firing and in the direct electrochemical conversion of coal-derived fuels for improved plant efficiency. The suitability of inorganic membrane materials for these purposes stems as much from thermal and chemical stability in coal plant operating conditions as from high performance in gas separations and power generation. Hydrophilic, micro-porous zeolite membrane structures are attractive for separating CO2 from N2 in gaseous waste streams due to the attraction of CO2 to the membrane surface and micropore walls that gives the advantage to CO2 transport. Recent studies have indicated that retention of the templating agent used in zeolite synthesis can further block N2 from the micropore interior and significantly improve CO2/N2 selectivity. However, the role of the templating agent in micro-porous transport has not been well investigated. In this work, gas sorption studies were conducted by high-pressure thermo-gravimetric analysis on Zeolite Y membrane materials to quantify the effect of the templating agent on CO2, N2, and H2O adsorption/desorption, as well as to examine the effect of humidification on overall membrane performance. In equilibrium conditions, the N2 sorption enthalpy was nearly unchanged by the presence of the templating agent, but the N2 pore occupation was reduced ˜1000x. Thus, the steric nature of the blocking of N2 from the micropores by the templating agent was confirmed. CO2 and H2O sorption enthalpies were similarly unaffected by the templating agent, and the micropore occupations were only reduced as much as the void volume taken up by the templating agent. Thus, the steric blocking effect did not occur for molecules more strongly attracted to the micropore walls. Additionally, in time-transient measurements the CO 2 and H2O mobilities were significantly enhanced by the presence

  4. Heat and mass transport resistances in vacuum membrane distillation per drop

    SciTech Connect

    Bandini, S.; Sarti, G.C.

    1999-07-01

    Vacuum membrane distillation (VMD) is a separation process based on the use of microporous hydrophobic membranes. The membrane is located between an aqueous phase and a permeate, which is kept under vacuum at pressure values below the equilibrium vapor pressure of the feed. The liquid stream vaporizes at one side of the membrane, and the vapors diffuse through the gas phase inside the membrane pores. The process rate and performance are affected highly by the transport phenomena both in the liquid phase and through the membrane. Heat- and mass-transfer resistance in the liquid phase, as well as mass-transfer resistance through the membrane, play an important role in determining the process performance. Based on VMD experimental data for several binary aqueous mixtures containing volatile organic compounds, a simple criterion to investigate the role of each transport resistance on the separation efficiency is discussed.

  5. Extracorporeal membrane oxygenation circuitry.

    PubMed

    Lequier, Laurance; Horton, Stephen B; McMullan, D Michael; Bartlett, Robert H

    2013-06-01

    The extracorporeal membrane oxygenation circuit is made of a number of components that have been customized to provide adequate tissue oxygen delivery in patients with severe cardiac and/or respiratory failure for a prolonged period of time (days to weeks). A standard extracorporeal membrane oxygenation circuit consists of a mechanical blood pump, gas-exchange device, and a heat exchanger all connected together with circuit tubing. Extracorporeal membrane oxygenation circuits can vary from simple to complex and may include a variety of blood flow and pressure monitors, continuous oxyhemoglobin saturation monitors, circuit access sites, and a bridge connecting the venous access and arterial infusion limbs of the circuit. Significant technical advancements have been made in the equipment available for short- and long-term extracorporeal membrane oxygenation applications. Contemporary extracorporeal membrane oxygenation circuits have greater biocompatibility and allow for more prolonged cardiopulmonary support time while minimizing the procedure-related complications of bleeding, thrombosis, and other physiologic derangements, which were so common with the early application of extracorporeal membrane oxygenation. Modern era extracorporeal membrane oxygenation circuitry and components are simpler, safer, more compact, and can be used across a wide variety of patient sizes from neonates to adults. PMID:23735989

  6. A Carbonaceous Membrane based on a Polymer of Intrinsic Microporosity (PIM-1) for Water Treatment

    PubMed Central

    Kim, Hee Joong; Kim, Dong-Gyun; Lee, Kyuchul; Baek, Youngbin; Yoo, Youngjae; Kim, Yong Seok; Kim, Byoung Gak; Lee, Jong-Chan

    2016-01-01

    As insufficient access to clean water is expected to become worse in the near future, water purification is becoming increasingly important. Membrane filtration is the most promising technologies to produce clean water from contaminated water. Although there have been many studies to prepare highly water-permeable carbon-based membranes by utilizing frictionless water flow inside the carbonaceous pores, the carbon-based membranes still suffer from several issues, such as high cost and complicated fabrication as well as relatively low salt rejection. Here, we report for the first time the use of microporous carbonaceous membranes via controlled carbonization of polymer membranes with uniform microporosity for high-flux nanofiltration. Further enhancement of membrane performance is observed by O2 plasma treatment. The optimized membrane exhibits high water flux (13.30 LMH Bar−1) and good MgSO4 rejection (77.38%) as well as antifouling properties. This study provides insight into the design of microporous carbonaceous membranes for water purification. PMID:27782212

  7. Microfabrication of High-Resolution Porous Membranes for Cell Culture

    PubMed Central

    Kim, Monica Y.; Li, David Jiang; Pham, Long K.; Wong, Brandon G.

    2014-01-01

    Microporous membranes are widely utilized in cell biology to study cell-cell signaling and cell migration. However, the thickness and low porosity of commercial track-etched membranes limit the quality of cell imaging and the degree of cell-cell contact that can be achieved on such devices. We employ photolithography-based microfabrication to achieve porous membranes with pore diameter as small as 0.9 μm, up to 40% porosity, and less than 5% variation in pore size. Through the use of a soap release layer, membranes as thin as 1 μm can be achieved. The thin membranes minimally disrupt contrast enhancement optics, thus allowing good quality imaging of unlabeled cells under white light, unlike commercial membranes. In addition, the polymer membrane materials display low autofluorescence even after patterning, facilitating high quality fluorescence microscopy. Finally, confocal imaging suggests that substantial cell-cell contact is possible through the pores of these thin membranes. This membrane technology can enhance existing uses of porous membranes in cell biology as well as enable new types of experiments. PMID:24567663

  8. Gas diffusion layers coated with a microporous layer containing hydrophilic carbon nanotubes for performance enhancement of polymer electrolyte fuel cells under both low and high humidity conditions

    NASA Astrophysics Data System (ADS)

    Kitahara, Tatsumi; Nakajima, Hironori; Okamura, Kosuke

    2015-06-01

    Gas diffusion layers (GDLs) coated with a hydrophobic microporous layer (MPL) composed of carbon black and polytetrafluoroethylene (PTFE) have been commonly used to improve the water management characteristics of polymer electrolyte fuel cells (PEFCs). However, the hydrophobic MPL coated GDL designed to prevent dehydration of the membrane under low humidity conditions is generally inferior at reducing flooding under high humidity conditions. It is therefore important to develop a robust MPL coated GDL that can enhance the PEFC performance regardless of the humidity conditions. In the present study, a GDL coated with an MPL containing hydrophilic carbon nanotubes (CNTs) was developed. The less hydrophobic pores incorporating CNTs are effective at conserving the membrane humidity under low humidity conditions. The MPL with CNTs is also effective at expelling excess water from the catalyst layer while maintaining oxygen flow pathways from the GDL substrate, allowing the mean flow pore diameter to be decreased to 2 μm without reducing the ability of the MPL to prevent flooding under high humidity conditions. An MPL coated GDL with a CNT content of 4 mass% exhibits significantly higher performance under both low and high humidity conditions than a hydrophobic MPL coated GDL.

  9. A COMPOSITE HOLLOW FIBER MEMBRANE-BASED PERVAPORATION PROCESS FOR SEPARATION OF VOCS FROM AQUEOUS SURFACTANT SOLUTIONS. (R825511C027)

    EPA Science Inventory

    The separation and recovery of VOCs from surfactant-containing aqueous solutions by a composite hollow fiber membrane-based pervaporation process has been studied. The process employed hydrophobic microporous polypropylene hollow fibers having a thin plasma polymerized silicon...

  10. Facile Carbonization of Microporous Organic Polymers into Hierarchically Porous Carbons Targeted for Effective CO2 Uptake at Low Pressures.

    PubMed

    Gu, Shuai; He, Jianqiao; Zhu, Yunlong; Wang, Zhiqiang; Chen, Dongyang; Yu, Guipeng; Pan, Chunyue; Guan, Jianguo; Tao, Kai

    2016-07-20

    The advent of microporous organic polymers (MOPs) has delivered great potential in gas storage and separation (CCS). However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of MOPs in CCS. Herein, facile chemical activation of the single microporous organic polymers (MOPs) resulted in a series of hierarchically porous carbons with hierarchically meso-microporous structures and high CO2 uptake capacities at low pressures. The MOPs precursors (termed as MOP-7-10) with a simple narrow micropore structure obtained in this work possess moderate apparent BET surface areas ranging from 479 to 819 m(2) g(-1). By comparing different activating agents for the carbonization of these MOPs matrials, we found the optimized carbon matrials MOPs-C activated by KOH show unique hierarchically porous structures with a significant expansion of dominant pore size from micropores to mesopores, whereas their microporosity is also significantly improved, which was evidenced by a significant increase in the micropore volume (from 0.27 to 0.68 cm(3) g(-1)). This maybe related to the collapse and the structural rearrangement of the polymer farmeworks resulted from the activation of the activating agent KOH at high temperature. The as-made hierarchically porous carbons MOPs-C show an obvious increase in the BET surface area (from 819 to 1824 m(2) g(-1)). And the unique hierarchically porous structures of MOPs-C significantly contributed to the enhancement of the CO2 capture capacities, which are up to 214 mg g(-1) (at 273 K and 1 bar) and 52 mg g(-1) (at 273 K and 0.15 bar), superior to those of the most known MOPs and porous carbons. The high physicochemical stabilities and appropriate isosteric adsorption heats as well as high CO2/N2 ideal selectivities endow these hierarchically porous carbon materials great potential in gas sorption and separation. PMID:27332739

  11. Facile Carbonization of Microporous Organic Polymers into Hierarchically Porous Carbons Targeted for Effective CO2 Uptake at Low Pressures.

    PubMed

    Gu, Shuai; He, Jianqiao; Zhu, Yunlong; Wang, Zhiqiang; Chen, Dongyang; Yu, Guipeng; Pan, Chunyue; Guan, Jianguo; Tao, Kai

    2016-07-20

    The advent of microporous organic polymers (MOPs) has delivered great potential in gas storage and separation (CCS). However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of MOPs in CCS. Herein, facile chemical activation of the single microporous organic polymers (MOPs) resulted in a series of hierarchically porous carbons with hierarchically meso-microporous structures and high CO2 uptake capacities at low pressures. The MOPs precursors (termed as MOP-7-10) with a simple narrow micropore structure obtained in this work possess moderate apparent BET surface areas ranging from 479 to 819 m(2) g(-1). By comparing different activating agents for the carbonization of these MOPs matrials, we found the optimized carbon matrials MOPs-C activated by KOH show unique hierarchically porous structures with a significant expansion of dominant pore size from micropores to mesopores, whereas their microporosity is also significantly improved, which was evidenced by a significant increase in the micropore volume (from 0.27 to 0.68 cm(3) g(-1)). This maybe related to the collapse and the structural rearrangement of the polymer farmeworks resulted from the activation of the activating agent KOH at high temperature. The as-made hierarchically porous carbons MOPs-C show an obvious increase in the BET surface area (from 819 to 1824 m(2) g(-1)). And the unique hierarchically porous structures of MOPs-C significantly contributed to the enhancement of the CO2 capture capacities, which are up to 214 mg g(-1) (at 273 K and 1 bar) and 52 mg g(-1) (at 273 K and 0.15 bar), superior to those of the most known MOPs and porous carbons. The high physicochemical stabilities and appropriate isosteric adsorption heats as well as high CO2/N2 ideal selectivities endow these hierarchically porous carbon materials great potential in gas sorption and separation.

  12. 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

  13. Development of phosphate-based ceramic membranes

    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. Investigation into anomalous total secondary electron yield for micro-porous Ag surface under oblique incidence conditions

    NASA Astrophysics Data System (ADS)

    Ye, M.; He, Y. N.; Hu, S. G.; Yang, J.; Wang, R.; Hu, T. C.; Peng, W. B.; Cui, W. Z.

    2013-09-01

    We study the dependence of total secondary electron yield (SEY) of micro-porous silver surface on incident angle of primary electron. First, we produce regular and random micro-porous surfaces on silver plated aluminium samples by photolithography pattern process and direct chemical etching method, respectively. Second, we study the dependence of the SEY characteristics of these surfaces on the primary electron incident angle from 0° to 60°. The experimental results show that micro-porous surface with large porosity can suppress SEY effectively either for normal incidence or oblique incidence. The maximum SEY of the directly chemical etched sample can reach a 45% reduction relative to the original flat sample. We also show the anomalous experimental phenomenon that the SEY of directly chemical etched sample with large porosity does not increase with incident angle. Third, we explain the complicated SEY dependence on incident angle qualitatively by the secondary electron trapping effect in micro-pores as well as the Monte Carlo simulation based on phenomenological model of secondary electron emission. Finally, we suggest a third order polynomial formula to describe the SEY dependence on incident angle which will be useful in particle simulation. In total, we demonstrate that micro-porous surface with large porosity is effective in SEY suppression under both normal and oblique incidence and thus the proposed direct chemical etching method is prospective in related areas such as multipactor improvement.

  15. Deformation of Microporous Carbons during N2, Ar, and CO2 Adsorption: Insight from the Density Functional Theory.

    PubMed

    Balzer, Christian; Cimino, Richard T; Gor, Gennady Y; Neimark, Alexander V; Reichenauer, Gudrun

    2016-08-16

    Using the nonlocal density functional theory, we investigate adsorption of N2 (77 K), Ar (77 K), and CO2 (273 K) and respective adsorption-induced deformation of microporous carbons. We show that the smallest micropores comparable in size and even smaller than the nominal molecular diameter of the adsorbate contribute significantly to the development of the adsorption stress. While pores of approximately the nominal adsorbate diameter exhibit no adsorption stress regardless of their filling level, the smaller pores cause expansive adsorption stresses up to almost 4 GPa. Accounting for this effect, we determined the pore-size distribution of a synthetic microporous carbon by simultaneously fitting its experimental CO2 adsorption isotherm (273 K) and corresponding adsorption-induced strain measured by in situ dilatometry. Based on the pore-size distribution and the elastic modulus fitted from CO2 data, we predicted the sample's strain isotherms during N2 and Ar adsorption (77 K), which were found to be in reasonable agreement with respective experimental data. The comparison of calculations and experimental results suggests that adsorption-induced deformation caused by micropores is not limited to the low relative pressures typically associated with the micropore filling, but is effective over the whole relative pressure range up to saturation pressure. PMID:27420036

  16. Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.

    PubMed

    Lv, Jinze; Zhu, Lizhong

    2013-01-01

    A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

  17. A dual-spatially-confined reservoir by packing micropores within dense graphene for long-life lithium/sulfur batteries.

    PubMed

    Li, Hongfei; Yang, Xiaowei; Wang, Xiaomin; He, Yu-Shi; Ye, Fangmin; Liu, Meinan; Zhang, Yuegang

    2016-01-28

    In lithium/sulfur batteries, micropores could bring about strong interactions with polysulfides, but could not alleviate the partial polysulfide overflowing outside because of the volume expansion of the lithiated sulfur. A dual-spatially-confined reservoir for sulfur by wrapping microporous carbon with dense graphene, micro@meso-porous DSC (dual-spatial carbon), is synthesized to solve this issue. Such a structure is prepared through two distinctive methods: graphene promoted in situ hydrothermal carbonization of organics to grow micropores on itself, and liquid mediated drying of graphene hydrogel to form mesoporous graphene frameworks. In contrast to previously reported hierarchical carbon/S, the inner micropores are mainly responsible for loading sulfur, which could help confine its particle size, thus increasing the electrical/ionic conductivity and the utilization of sulfur, and restrain lithium polysulfide dissolution because of strong interaction with pore walls; while the outer mesopores act as another reservoir to stabilize the overflowed polysulfide and to enhance the Li(+) transport. The S-micro@meso-porous DSC cathode exhibits better discharge capacity and cycling performance than S-microporous AC and S-micro@macro-porous DSC, i.e., 59% and 37% higher capacity remaining at 0.5 C than the latter two, respectively.

  18. Chelating agent-free, vapor-assisted crystallization method to synthesize hierarchical microporous/mesoporous MIL-125 (Ti).

    PubMed

    McNamara, Nicholas D; Hicks, Jason C

    2015-03-11

    Titanium-based microporous heterogeneous catalysts are widely studied but are often limited by the accessibility of reactants to active sites. Metal-organic frameworks (MOFs), such as MIL-125 (Ti), exhibit enhanced surface areas due to their high intrinsic microporosity, but the pore diameters of most microporous MOFs are often too small to allow for the diffusion of larger reactants (>7 Å) relevant to petroleum and biomass upgrading. In this work, hierarchical microporous MIL-125 exhibiting significantly enhanced interparticle mesoporosity was synthesized using a chelating-free, vapor-assisted crystallization method. The resulting hierarchical MOF was examined as an active catalyst for the oxidation of dibenzothiophene (DBT) with tert-butyl hydroperoxide and outperformed the solely microporous analogue. This was attributed to greater access of the substrate to surface active sites, as the pores in the microporous analogues were of inadequate size to accommodate DBT. Moreover, thiophene adsorption studies suggested the mesoporous MOF contained larger amounts of unsaturated metal sites that could enhance the observed catalytic activity. PMID:25695286

  19. Random lasing of microporous surface of Cr{sup 2+}:ZnSe crystal induced by femtosecond laser

    SciTech Connect

    Yang, Xianheng; Feng, Guoying E-mail: zhoush@scu.edu.cn; Yao, Ke; Yi, Jiayu; Zhang, Hong; Zhou, Shouhuan E-mail: zhoush@scu.edu.cn

    2015-06-15

    We demonstrate a random lasing emission based on microporous surface of Cr{sup 2+}:ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10{sup −4} Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ∼13 μm and smaller ones with ∼1.2 μm on the surface of Cr{sup 2+}:ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr{sup 2+}:ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr{sup 2+}:ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength.

  20. Self-formation of microporous polysulfone hollow fiber using a single nozzle spinneret and reduction of phase-inversion speed

    NASA Astrophysics Data System (ADS)

    Kim, Hyung Jin; Jang, Chang Sik; Kim, Byeong Hee; Seo, Young Ho

    2016-06-01

    This study proposed a simple fabrication technique for microporous hollow fibers whose inner channel was naturally formed because of a slow phase inversion speed. Conventionally, microporous hollow fibers have been fabricated by extruding a polymer solution through the outer nozzle and a bore liquid through the inner nozzle of a dual nozzle spinneret. Injecting a bore liquid played a key role for the formation of a hollow structure. In this study, the self-formation of a hollow structure of microporous fiber was developed using a single nozzle spinneret without a bore liquid. A sharp tip single nozzle spinneret of 200 µm in diameter was fabricated by the wetting effect of a liquid pre-polymer of polydimethylsiloxane, and polysulfone solution was extruded through the prepared single nozzle spinneret. The temperature of the coagulant bath was controlled in order to reduce the speed of phase change, because the phase-change speed depended on the temperature of the coagulant solution. An inner channel in the microporous fiber was successfully fabricated by reducing the phase-change speed and by increasing the solidification speed. The inner diameter of the microporous hollow fiber was decreased as the temperature of the coagulant bath was increased, and eventually the inner channel was not formed at the higher bath temperature rather than 25 °C.

  1. DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

    SciTech Connect

    Wei-Heng Shih; Tejas Patil; Qiang Zhao

    2003-03-25

    The huge emissions of carbon dioxide from fossil fuel fired power plants and industrial plants over the last century have resulted in an increase of the atmospheric carbon dioxide concentration. Climatological modeling work has predicted severe climate disruption as a result of the trapping of heat due to CO{sub 2}. As an attempt to address this global warming effect, DOE has initiated the Vision 21 concept for future power plants. We first synthesized mesoporous aluminosilicates that have high surface area and parallel pore channels for membrane support materials. Later we synthesized microporous aluminosilicates as the potential thin membrane materials for selective CO{sub 2} adsorption. The pore size is controlled to be less that 1 nm so that the adsorption of CO{sub 2} on the pore wall will block the passage of N{sub 2}. Mesoporous and precipitated alumina were synthesized as the base material for CO{sub 2} adsorbent. The porous alumina is doped with Ba to enhance its CO{sub 2} affinity due to the basicity of Ba. It is shown by gas chromatograph (GC) that the addition of Ba enhances the separation CO{sub 2} from N{sub 2}. It was found that mesoporous alumina has larger specific surface area and better selectivity of CO{sub 2} than precipitated alumina. Ba improves the affinity of mesoporous alumina with CO{sub 2}. Phase may play an important role in selective adsorption of CO{sub 2}. It is speculated that mesoporous alumina is more reactive than precipitated alumina creating the xBaO {center_dot}Al{sub 2}O{sub 3} phase that may be more affinitive to CO{sub 2} than N{sub 2}. On the other hand, the barium aluminates phase (Ba{sub 3}Al{sub 2}O{sub 6}) in the mesoporous sample does not help the adsorption of CO{sub 2}. Microporous aluminosilicate was chosen as a suitable candidate for CO{sub 2}/N{sub 2} separation because the pore size is less than 10 {angstrom}. If a CO{sub 2} adsorbent is added to the microporous silica, the adsorption of CO{sub 2} can block the

  2. Electroosmotic flow can generate ion current rectification in nano- and micropores.

    PubMed

    Yusko, Erik C; An, Ran; Mayer, Michael

    2010-01-26

    This paper introduces a strategy for generating ion current rectification through nano- and micropores. This method generates ion current rectification by electroosmotic-driven flow of liquids of varying viscosity (and hence varying conductance) into or out of the narrowest constriction of a pore. The magnitude of current rectification was described by a rectification factor, R(f), which is defined by the ratio of the current measured at a positive voltage divided by the current measured at a negative voltage. This method achieved rectification factors in the range of 5-15 using pores with diameters ranging from 10 nm to 2.2 microm. These R(f) values are similar to the rectification factors reported in other nanopore-based methods that did not employ segmented surface charges. Interestingly, this work showed that in cylindrical nanopores with diameters of 10 nm and a length of at least 275 nm, electroosmotic flow was present and could generate ion current rectification. Unlike previous methods for generating ion current rectification that require nanopores with diameters comparable to the Debye length, this work demonstrated ion current rectification in micropores with diameters 500 times larger than the Debye length. Thus this method extends the concept of fluidic diodes to the micropore range. Several experiments designed to alter or remove electroosmotic flow through the pore demonstrated that electroosmotic flow was required for the mode of ion current rectification reported here. Consequently, the magnitude of current rectification could be used to indicate the presence of electroosmotic flow and the breakdown of electroosmotic flow with decreasing ionic strength and hence increasing electric double layer overlap inside nanopores.

  3. Ab initio molecular dynamics study of the interlayer and micropore structure of aqueous montmorillonite clays

    NASA Astrophysics Data System (ADS)

    Suter, James L.; Kabalan, Lara; Khader, Mahmoud; Coveney, Peter V.

    2015-11-01

    Ab initio molecular dynamics simulations have been performed to gain an understanding of the interfacial microscopic structure and reactivity of fully hydrated clay edges. The models studied include both micropore and interlayer water. We identify acidic sites through dissociation mechanisms; the resulting ions can be stabilized by both micropore and interlayer water. We find clay edges possess a complex amphoteric behavior, which depends on the face under consideration and the location of isomorphic substitution. For the neutral (1 1 0) surface, we do not observe any dissociation on the timescale accessible. The edge terminating hydroxyl groups participate in a hydrogen bonded network of water molecules that spans the interlayer between periodic images of the clay framework. With isomorphic substitutions in the tetrahedral layer of the (1 1 0) clay edge, we find the adjacent exposed apical oxygen behaves as a Brönsted base and abstracts a proton from a nearby water molecule, which in turn removes a proton from an AlOH2 group. With isomorphic substitutions in the octahedral layer of the (1 1 0) clay edge the adjacent exposed apical oxygen atom does not abstract a proton from the water molecules, but increases the number of hydrogen bonded water molecules (from one to two). Acid treated clays are likely to have both sites protonated. The (0 1 0) surface does not have the same interfacial hydrogen bonding structure; it is much less stable and we observe dissociation of half the terminal SiOH groups (tbnd Sisbnd Osbnd H → tbnd Sisbnd O- + H+) in our models. The resulting anions are stabilized by solvation from both micropore and interlayer water molecules. This suggests that, when fully hydrated, the (0 1 0) surface can act as a Brönsted acid, even at neutral pH.

  4. Highly selective and stable carbon dioxide uptake in polyindole-derived microporous carbon materials.

    PubMed

    Saleh, Muhammad; Tiwari, Jitendra N; Kemp, K Christain; Yousuf, Muhammad; Kim, Kwang S

    2013-05-21

    Adsorption with solid sorbents is considered to be one of the most promising methods for the capture of carbon dioxide (CO₂) from power plant flue gases. In this study, microporous carbon materials used for CO₂ capture were synthesized by the chemical activation of polyindole nanofibers (PIF) at temperatures from 500 to 800 °C using KOH, which resulted in nitrogen (N)-doped carbon materials. The N-doped carbon materials were found to be microporous with an optimal adsorption pore size for CO₂ of 0.6 nm and a maximum (Brunauer-Emmett-Teller) BET surface area of 1185 m(2) g(-1). The PIF activated at 600 °C (PIF6) has a surface area of 527 m(2) g(-1) and a maximum CO₂ storage capacity of 3.2 mmol g(-1) at 25 °C and 1 bar. This high CO₂ uptake is attributed to its highly microporous character and optimum N content. Additionally, PIF6 material displays a high CO₂ uptake at low pressure (1.81 mmol g(-1) at 0.2 bar and 25 °C), which is the best low pressure CO₂ uptake reported for carbon-based materials. The adsorption capacity of this material remained remarkably stable even after 10 cycles. The isosteric heat of adsorption was calculated to be in the range of 42.7-24.1 kJ mol(-1). Besides the excellent CO₂ uptake and stability, PIF6 also exhibits high selectivity values for CO₂ over N₂, CH₄, and H₂ of 58.9, 12.3, and 101.1 at 25 °C, respectively, and these values are significantly higher than reported values.

  5. Molecular simulation of RMM: ordered mesoporous SBA-15 type material having microporous ZSM-5 walls.

    PubMed

    Sonwane, C G; Li, Q

    2005-09-29

    SBA-15 is a novel porous material with uniform size mesopores arranged in a regular pattern. The adjacent mesopores are connected to each other by microporous walls. The major disadvantages of these materials are that the walls are amorphous and have low thermal, hydrothermal, and mechanical stability. Recently, there have been a few attempts to either coat the walls of SBA-15 by microporous crystalline zeolites or to fabricate SBA-15 using CMK-3 in such a way that the walls are made up of ZSM-5. The present work provides a first-ever study of RMM (replicated mesoporous materials, which are SBA-15 like ordered mesoporous materials with walls made up of ZSM-5) using molecular modeling. A random orientation of the unit cells and the distribution of sizes of the supercells located at nucleation sites would be ideal to model the RMM. However, such a study would introduce more uncertainties with regard to voids between the individual supercells, noncrystalline silica, and the location of active sites where the nucleation occurs. In a simpler model studied in the present work, the walls of SBA-15 were made up of regularly arranged ZSM-5 having the same orientation. The structure was characterized by estimating the nitrogen accessible area/volume by Connolly surfaces, small-angle and wide-angle X-ray diffraction patterns, methane adsorption, and ice as a probe to study the pore structure. It was found that RMMs have significantly higher methane adsorption capacity compared to SBA-15 and the majority of methane is adsorbed in the microporous walls of RMM. Further research in the field of RMM is needed to obtain the details of zeolitic wall structure. PMID:16853309

  6. Microporous silica prepared by organic templating: Relationship between the molecular template and pore structure

    SciTech Connect

    Lu, Y.; Brinker, C.J. |; Cao, G.; Kale, R.P.; Prabakar, S.; Lopez, G.P.

    1999-05-01

    Microporous silica materials with a controlled pore size and a narrow pore size distribution have been prepared by sol-gel processing using an organic-templating approach. Microporous networks were formed by pyrolytic removal of organic ligands (methacryloxypropyl groups) from organic/inorganic hybrid materials synthesized by copolymerization of 3-methacryloxypropylsilane (MPS) and tetraethoxysilane (TEOS). Molecular simulations and experimental measurements were conducted to examine the relationship between the microstructural characteristics of the porous silica (e.g., pore size, total pore volume, and pore connectivity) and the size and amount of organic template ligands added. Adsorption measurements suggest that the final porosity of the microporous silica is due to both primary pores (those present in the hybrid material prior to pyrolysis) and secondary pores (those created by pyrolytic removal of organic templates). Primary pores were inaccessible to N{sub 2} at 77 K but accessible to CO{sub 2} at 195 K; secondary pores were accessible to both N{sub 2} (at 77 K) and CO{sub 2} (at 195 K) in adsorption measurements. Primary porosity decreases with the amount of organic ligands added because of the enhanced densification of MPS/TEOS hybrid materials as the mole fraction of trifunctional MPS moieties increases. Pore volumes measured by nitrogen adsorption experiments at 77 K suggest that the secondary (template-derived) porosity exhibits a percolation behavior as the template concentration is increased. Gas permeation experiments indicate that the secondary pores are approximately 5 {angstrom} in diameter, consistent with predictions based on molecular simulations.

  7. Through-plane conductivities of membranes for nonaqueous redox flow batteries

    SciTech Connect

    Anderson, Travis Mark; Small, Leo J.; Pratt, III, Harry D.; Hudak, Nicholas S.

    2015-08-13

    In this study, nonaqueous redox flow batteries (RFB) leverage nonaqueous solvents to enable higher operating voltages compared to their aqueous counterparts. Most commercial components for flow batteries, however, are designed for aqueous use. One critical component, the ion-selective membrane, provides ionic conductance between electrodes while preventing crossover of electroactive species. Here we evaluate the area-specific conductances and through-plane conductivities of commercially available microporous separators (Celgard 2400, 2500) and anion exchange membranes (Neosepta AFX, Neosepta AHA, Fumasep FAP-450, Fumasep FAP-PK) soaked in acetonitrile, propylene carbonate, or two imidazolium-based ionic liquids. Fumasep membranes combined with acetonitrile-based electrolyte solutions provided the highest conductance values and conductivities by far. When tested in ionic liquids, all anion exchange membranes displayed conductivities greater than those of the Celgard microporous separators, though the separators’ decreased thickness-enabled conductances on par with the most conductive anion exchange membranes. Ionic conductivity is not the only consideration when choosing an anion exchange membrane; testing of FAP-450 and FAP-PK membranes in a nonaqueous RFB demonstrated that the increased mechanical stability of PEEK-supported FAP-PK minimized swelling, in turn decreasing solvent mediated crossover and enabling greater electrochemical yields (40% vs. 4%) and Coulombic efficiencies (94% vs. 90%) compared to the unsupported, higher conductance FAP-450.

  8. Through-plane conductivities of membranes for nonaqueous redox flow batteries

    DOE PAGES

    Anderson, Travis Mark; Small, Leo J.; Pratt, III, Harry D.; Hudak, Nicholas S.

    2015-08-13

    In this study, nonaqueous redox flow batteries (RFB) leverage nonaqueous solvents to enable higher operating voltages compared to their aqueous counterparts. Most commercial components for flow batteries, however, are designed for aqueous use. One critical component, the ion-selective membrane, provides ionic conductance between electrodes while preventing crossover of electroactive species. Here we evaluate the area-specific conductances and through-plane conductivities of commercially available microporous separators (Celgard 2400, 2500) and anion exchange membranes (Neosepta AFX, Neosepta AHA, Fumasep FAP-450, Fumasep FAP-PK) soaked in acetonitrile, propylene carbonate, or two imidazolium-based ionic liquids. Fumasep membranes combined with acetonitrile-based electrolyte solutions provided the highest conductancemore » values and conductivities by far. When tested in ionic liquids, all anion exchange membranes displayed conductivities greater than those of the Celgard microporous separators, though the separators’ decreased thickness-enabled conductances on par with the most conductive anion exchange membranes. Ionic conductivity is not the only consideration when choosing an anion exchange membrane; testing of FAP-450 and FAP-PK membranes in a nonaqueous RFB demonstrated that the increased mechanical stability of PEEK-supported FAP-PK minimized swelling, in turn decreasing solvent mediated crossover and enabling greater electrochemical yields (40% vs. 4%) and Coulombic efficiencies (94% vs. 90%) compared to the unsupported, higher conductance FAP-450.« less

  9. Importance of Micropore-Mesopore Interfaces in Carbon Dioxide Capture by Carbon-Based Materials.

    PubMed

    Durá, Gema; Budarin, Vitaliy L; Castro-Osma, José A; Shuttleworth, Peter S; Quek, Sophie C Z; Clark, James H; North, Michael

    2016-08-01

    Mesoporous carbonaceous materials (Starbons®) derived from low-value/waste bio-resources separate CO2 from CO2 /N2 mixtures. Compared to Norit activated charcoal (AC), Starbons® have much lower microporosities (8-32 % versus 73 %) yet adsorb up to 65 % more CO2 . The presence of interconnected micropores and mesopores is responsible for the enhanced CO2 adsorption. The Starbons® also showed three-four times higher selectivity for CO2 adsorption rather than N2 adsorption compared to AC.

  10. Importance of Micropore-Mesopore Interfaces in Carbon Dioxide Capture by Carbon-Based Materials.

    PubMed

    Durá, Gema; Budarin, Vitaliy L; Castro-Osma, José A; Shuttleworth, Peter S; Quek, Sophie C Z; Clark, James H; North, Michael

    2016-08-01

    Mesoporous carbonaceous materials (Starbons®) derived from low-value/waste bio-resources separate CO2 from CO2 /N2 mixtures. Compared to Norit activated charcoal (AC), Starbons® have much lower microporosities (8-32 % versus 73 %) yet adsorb up to 65 % more CO2 . The presence of interconnected micropores and mesopores is responsible for the enhanced CO2 adsorption. The Starbons® also showed three-four times higher selectivity for CO2 adsorption rather than N2 adsorption compared to AC. PMID:27336368

  11. Conjugated Microporous Poly(Benzochalcogenadiazole)s for Photocatalytic Oxidative Coupling of Amines under Visible Light.

    PubMed

    Wang, Zi Jun; Garth, Kim; Ghasimi, Saman; Landfester, Katharina; Zhang, Kai A I

    2015-10-26

    Metal-free visible-light photocatalysts offer a clean, sustainable solution to many pressing environmental issues. Herein, we present a molecular design strategy to fine-tune the valence and conduction band levels of a series of conjugated microporous polymer networks based on poly(benzochalcogenadiazole) for heterogeneous photocatalysis. Enhanced photocatalytic efficiency was observed by altering the chalcogene moieties in the electron-accepting benzochalcogenadiazole unit of the polymer backbone structure. Photooxidative coupling of benzylamines was chosen as a model reaction. This design strategy leading to enhanced efficiency could potentially improve a wide range of photoredox reactions.

  12. Efficient fixation of CO2 by a zinc-coordinated conjugated microporous polymer.

    PubMed

    Xie, Yong; Wang, Ting-Ting; Yang, Rui-Xia; Huang, Nian-Yu; Zou, Kun; Deng, Wei-Qiao

    2014-08-01

    Zinc-coordinated conjugated microporous polymers (Zn-CMPs), prepared by linking salen zinc and 1,3,5-triethynylbenzene, exhibit extraordinary activities (turnover frequencies of up to 11600 h(-1) ), broad substrate scope, and group tolerance for the synthesis of functional organic carbonates by coupling epoxides with CO2 at 120 °C and 3.0 MPa without the use of additional solvents. The catalytic activity of Zn-CMP is comparable to those of homogeneous catalysts and superior to those of other heterogeneous catalysts. This catalyst could be reused more than ten times without a significant decrease in performance.

  13. Performance of a cross-flow humidifier with a high flux water vapor transport membrane

    NASA Astrophysics Data System (ADS)

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-01

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  14. Performance of a Cross-Flow Humidifier with a High Flux Water Vapor Transport Membrane

    SciTech Connect

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-30

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  15. Membrane distillation

    NASA Astrophysics Data System (ADS)

    Bryk, Mikhail T.; Nigmatullin, R. R.

    1994-12-01

    Studies in the field of membrane distillation are analysed. A critical analysis of the theoretical and experimental investigations of membrane distillation is presented. Attention is concentrated on the mechanism of mass transfer and the influence of various external factors on the process characteristics. Questions concerning the creation of modules and apparatus for membrane distillation and aspects of the practical employment of such distillation in order to obtain pure water, for the purification of waste water, and for the concentration of technological solutions in various branches of industry are considered quite fully. The advantages and disadvantages of membrane distillation compared with other membrane methods are analysed. The bibliography includes 97 references.

  16. Effect of deacetylation degree in chitosan composite membranes on pervaporation performance

    SciTech Connect

    Lee, Y.M.; Park, H.B.; Nam, S.Y.; Won, J.M.; Kim, H.

    1998-06-01

    The effect of the degree of deacetylation in chitosan composite membranes on their pervaporation performance for ethanol dehydration was investigated. The degree of deacetylation of chitosans was measured by using an infrared spectroscopic method and elemental analysis. The chitosan composite membranes were prepared by coating a chitosan solution onto a microporous polyethersulfone membrane with 3--7 nm pore sizes. Then the surface of the top layer (chitosan) of well-dried membranes was crosslinked with sulfuric acid, and pervaporation experiments for binary mixtures (water-ethanol) were carried out at various conditions. In the case of a chitosan membrane with a high degree of deacetylation, the flux increases while the separation factor decreases compared with membranes with a low degree of deacetylation.

  17. Influences of Hydrogen Micropores and Intermetallic Particles on Fracture Behaviors of Al-Zn-Mg-Cu Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Su, Hang; Yoshimura, Takuro; Toda, Hiroyuki; Bhuiyan, Md. Shahnewaz; Uesugi, Kentaro; Takeuchi, Akihisa; Sakaguchi, Nobuhito; Watanabe, Yoshio

    2016-09-01

    The combined effects of hydrogen micropores and intermetallic particles on the voids initiation and growth behavior of Al-Zn-Mg-Cu aluminum alloys during deformation and fracture are investigated with the help of the high-resolution X-ray tomography. It is interesting to note that the high-hydrogen concentration induced by an EDM cutting process results in the initiation of quasi-cleavage fracture near surface. With the increase of strain, the quasi-cleavage fracture is gradually replaced by dimple fracture. Voids initiation related to the dimple fracture is caused by both intermetallic particles fracture and interfacial debonding between particles and matrix. The nucleation of hydrogen micropores on intermetallic particles accelerates the voids initiation. The existence of triaxial stress ahead of the tip of a quasi-cleavage crack enhances growth rate for both hydrogen micropores and voids.

  18. Asymmetric Membrane Osmotic Capsules for Terbutaline Sulphate

    PubMed Central

    Gobade, N. G.; Koland, Marina; Harish, K. H.

    2012-01-01

    The aim of the present study was to design an asymmetric membrane capsule, an osmotic pump-based drug delivery system of ethyl cellulose for controlled release of terbutaline sulphate. asymmetric membrane capsules contains pore-forming water soluble additive, sorbitol in different concentrations in the capsule shell membrane, which after coming in contact with water, dissolves, resulting in an in situ formation of a microporous structure. The terbutaline sulphate is a β-adrenoreceptor agonist widely used in the treatment of asthma. The oral dosage regimen of terbutaline sulphate is 5 mg twice or thrice daily, the plasma half-life is approximate 3-4 h and it produces GI irritation with extensive first pass metabolism. Hence, terbutaline sulphate was chosen as a model drug with an aim to develop controlled release system. Different formulations of ethyl cellulose were prepared by phase inversion technique using different concentrations of sorbitol as pore forming agent. It was found that the thickness of the prepared asymmetric membrane capsules was increased with increase in concentration of ethyl cellulose and pore forming agent, i.e. sorbitol. The dye release study in water and 10% sodium chloride solution indicates that, the asymmetric membrane capsules follow osmotic principle to release content. The pores formed due to sorbitol were confirmed by microscopic observation of transverse section of capsule membrane. Data of in vitro release study of terbutaline sulphate from asymmetric membrane capsules indicated that, the capsules prepared with 10% and 12.5% of ethyl cellulose and 25% of sorbitol released as much as 97.44% and 76.27% in 12 h, respectively with zero order release rate. Hence asymmetric membrane capsule of 10% ethyl cellulose and 25% of sorbitol is considered as optimum for controlled oral delivery of terbutaline sulphate. PMID:23204625

  19. Asymmetric membrane osmotic capsules for terbutaline sulphate.

    PubMed

    Gobade, N G; Koland, Marina; Harish, K H

    2012-01-01

    The aim of the present study was to design an asymmetric membrane capsule, an osmotic pump-based drug delivery system of ethyl cellulose for controlled release of terbutaline sulphate. asymmetric membrane capsules contains pore-forming water soluble additive, sorbitol in different concentrations in the capsule shell membrane, which after coming in contact with water, dissolves, resulting in an in situ formation of a microporous structure. The terbutaline sulphate is a β-adrenoreceptor agonist widely used in the treatment of asthma. The oral dosage regimen of terbutaline sulphate is 5 mg twice or thrice daily, the plasma half-life is approximate 3-4 h and it produces GI irritation with extensive first pass metabolism. Hence, terbutaline sulphate was chosen as a model drug with an aim to develop controlled release system. Different formulations of ethyl cellulose were prepared by phase inversion technique using different concentrations of sorbitol as pore forming agent. It was found that the thickness of the prepared asymmetric membrane capsules was increased with increase in concentration of ethyl cellulose and pore forming agent, i.e. sorbitol. The dye release study in water and 10% sodium chloride solution indicates that, the asymmetric membrane capsules follow osmotic principle to release content. The pores formed due to sorbitol were confirmed by microscopic observation of transverse section of capsule membrane. Data of in vitro release study of terbutaline sulphate from asymmetric membrane capsules indicated that, the capsules prepared with 10% and 12.5% of ethyl cellulose and 25% of sorbitol released as much as 97.44% and 76.27% in 12 h, respectively with zero order release rate. Hence asymmetric membrane capsule of 10% ethyl cellulose and 25% of sorbitol is considered as optimum for controlled oral delivery of terbutaline sulphate. PMID:23204625

  20. Effects of thermal efficiency in DCMD and the preparation of membranes with low thermal conductivity

    NASA Astrophysics Data System (ADS)

    Li, Zhehao; Peng, Yuelian; Dong, Yajun; Fan, Hongwei; Chen, Ping; Qiu, Lin; Jiang, Qi

    2014-10-01

    The effects of the membrane characteristics and operational conditions on the vapor flux and thermal efficiency in a direct contact membrane distillation (DCMD) process were studied with a mathematical simulation. The membrane temperature, driving force of vapor transfer, membrane distillation coefficient, etc. were used to analyze the effects. The operating conditions that increased the vapor flux improved the thermal efficiency. The membrane characteristics of four microporous membranes and their performances in DCMD were compared. A polysulfone (PSf) membrane prepared via vapor-induced phase separation exhibited the lowest thermal conductivity. The PSf and polyvinylidene difluoride (PVDF) membranes were modified using SiO2 aerogel blending and coating to reduce the thermal conductivity of the membrane. The coating process was more effective than the blending process toward this end. The changes in the structure of the modified membrane were observed with a scanning electron microscope. Si was found on the modified membrane surface with an energy spectrometer. The PVDF composite and support membranes were tested during the DCMD process; the composite membrane had a higher vapor flux and a better thermal efficiency than the support. A new method based on a 3ω technique was used to measure the thermal conductivity of the membranes.

  1. Mathematical modeling of a flat-membrane-controlled release device

    SciTech Connect

    Ramraj, R.; Farrell, S.; Loney, N.W.

    1999-08-01

    The closed form solution to a mathematical model of a flat membrane device successfully predicts the release profile of benzoic acid. Physically, the device consists of a given concentration of benzoic acid in octanol (reservoir) bounded by a microporous flat film (Cellgard 2400) with water-filled pores. The prediction shows excellent agreement with the experimentally derived release profile (maximum difference < 10%). Predicted results are obtained from the use of the steady state plus the first term of the transient solution (infinite series) and with the use of the first nonzero eigenvalue.

  2. Effects of CO{sub 2} activation on electrochemical performance of microporous carbons derived from poly(vinylidene fluoride)

    SciTech Connect

    Lee, Seul-Yi; Park, Soo-Jin

    2013-11-15

    In this work, we have prepared microporous carbons (MPCs) derived from poly(vinylidene fluoride) (PVDF), and the physical activation of MPCs using CO{sub 2} gas is subsequently carried out with various activation temperatures to investigate the electrochemical performance. PVDF is successfully converted into MPCs with a high specific surface area and well-developed micropores. After CO{sub 2} activation, the specific surface areas of MPCs (CA-MPCs) are enhanced by 12% compared with non-activated MPCs. With increasing activation temperature, the micropore size distributions of A-MPCs also become narrower and shift to larger pore size. It is also confirmed that the CO{sub 2} activation had developed the micropores and introduced the oxygen-containing groups to MPCs′ surfaces. From the results, the specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on CA-MPCs are distinctly improved through CO{sub 2} activation. The highest specific capacitance of the A-MPCs activated at 700 °C is about 125 F/g, an enhancement of 74% in comparison with NA-MPCs, at a discharge current of 2 A/g in a 6 M KOH electrolyte solution. We also found that micropore size of 0.67 nm has a specific impact on the capacitance behaviors, besides the specific surface area of the electrode samples. - Graphical abstract: The A-MPC samples with high specific surface area (ranging from 1030 to 1082 m{sup 2}/g), corresponding to micropore sizes of 0.67 and 0.72 nm, and with the amount of oxygen-containing groups ranging from 3.2% to 4.4% have been evaluated as electrodes for EDLC applications. . Display Omitted - Highlights: • Microporous carbons (MPCs) were synthesized without activation process. • Next, we carried out the CO{sub 2} activation of MPCs with activation temperatures. • It had developed the micropores and introduced the O-functional groups to MPCs. • The highest specific capacitance: 125 F/g, an increase of 74% compared to MPCs.

  3. Using Microporous Polytetrafluoroethylene Thin Sheets as a Flexible Solar Diffuser to Minimize Sunlight Glint to Cameras in Space

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2016-01-01

    An innovative design of using microporous PTFE thin sheets as a solar diffuser for MLI blankets or mechanical structure has been developed. It minimizes sunlight or stray-light glint to cameras when it is incident on these components in space. A microporous black PTFE thin sheet solar diffuser has been qualified for flight at NASA GSFC and installed to the TAGSAM arm MLI, OCAMS PolyCam sunshade MLI and SamCam motor riser MLI in the NASA OSIRIS-REx mission to meet the SamCam camera BRDF requirement.

  4. UV Raman spectroscopic studies on active sites and synthesis mechanisms of transition metal-containing microporous and mesoporous materials.

    PubMed

    Fan, Fengtao; Feng, Zhaochi; Li, Can

    2010-03-16

    Microporous and mesoporous materials are widely used as catalysts and catalyst supports. Although the incorporation of transition metal ions into the framework of these materials (by isomorphous substitution of Al and Si) is an effective means of creating novel catalytic activity, the characterization of the transition metal species within these materials is difficult. Both the low concentration of the highly dispersed transition metal and the coexistence of extraframework transition metal species present clear challenges. Moreover, the synthetic mechanisms that operate under the highly inhomogeneous conditions of hydrothermal synthesis are far from well understood. A useful technique for addressing these challenges is UV Raman spectroscopy, which is a powerful technique for catalyst characterization and particularly for transition metal-containing microporous and mesoporous materials. Conventional Raman spectroscopy, using visible and IR wavelengths, often fails to provide the information needed for proper characterization as a result of fluorescence interference. But shifting the excitation source to the UV range addresses this difficulty: interference from fluorescence (which typically occurs at 300-700 nm or greater) is greatly diminished. Moreover, signal intensity is enhanced because Raman intensity is proportional to the fourth power of the scattered light frequency. In this Account, we review recent advances in UV Raman spectroscopic characterization of (i) highly dispersed transition metal oxides on supports, (ii) transition metal ions in the framework of microporous and mesoporous materials, and (iii) the synthetic mechanisms involved in making microporous materials. By taking advantage of the strong UV resonance Raman effect, researchers have made tremendous progress in the identification of isolated transition metal ions incorporated in the framework of microporous and mesoporous materials such as TS-1, Ti-MCM-41, Fe-ZSM-5, and Fe-SBA-15. The synthetic

  5. Bioprocess intensification of antibiotic production by Streptomyces coelicolor A3(2) in micro-porous culture.

    PubMed

    Ndlovu, T M; Ward, A C; Glassey, J; Eskildsen, J; Akay, G

    2015-04-01

    A novel functionalized micro-porous matrix was developed with well-controlled physicochemical proprieties such as pore size and surface chemistry. The matrix was used as a solid support in the growth of "Streptomyces coelicolor" A3(2) to enhance the production of antibiotics. The results shown support a higher production of prodigiosin and actinorhodin with overall production increase of 2-5 and 6-17, respectively, compared to conventional submerged liquid culture, offering a potential improvement in volumetric productivity. Scanning Electron Microscopy was used to evaluate pore size as well as bacterial adhesion, penetration, proliferation and migration within the micro-porous matrix.

  6. The use of fibrous, supramolecular membranes and human tubular cells for renal epithelial tissue engineering: towards a suitable membrane for a bioartificial kidney.

    PubMed

    Dankers, Patricia Y W; Boomker, Jasper M; Huizinga-van der Vlag, Ali; Smedts, Frank M M; Harmsen, Martin C; van Luyn, Marja J A

    2010-11-10

    A bioartificial kidney, which is composed of a membrane cartridge with renal epithelial cells, can substitute important kidney functions in patients with renal failure. A particular challenge is the maintenance of monolayer integrity and specialized renal epithelial cell functions ex vivo. We hypothesized that this can be improved by electro-spun, supramolecular polymer membranes which show clear benefits in ease of processability. We found that after 7 d, in comparison to conventional microporous membranes, renal tubular cells cultured on top of our fibrous supramolecular membranes formed polarized monolayers, which is prerequisite for a well-functioning bioartificial kidney. In future, these supramolecular membranes allow for incorporation of peptides that may increase cell function even further.

  7. Capture and Reversible Storage of Volatile Iodine by Novel Conjugated Microporous Polymers Containing Thiophene Units.

    PubMed

    Qian, Xin; Zhu, Zhao-Qi; Sun, Han-Xue; Ren, Feng; Mu, Peng; Liang, Weidong; Chen, Lihua; Li, An

    2016-08-17

    Conjugated microporous polymers having thiophene building blocks (SCMPs), which originated from ethynylbenzene monomers with 2,3,5-tribromothiophene, were designedly synthesized through Pd(0)/CuI catalyzed Sonogashira-Hagihara cross-coupling polymerization. The morphologies, structure and physicochemical properties of the as-synthesized products were characterized through scanning electron microscope (SEM), thermogravimeter analysis (TGA), (13)C CP/MAS solid state NMR and Fourier transform infrared spectroscope (FTIR) spectra. Nitrogen sorption-desorption analysis shows that the as-synthesized SCMPs possesses a high specific surface area of 855 m(2) g(-1). Because of their abundant porosity, π-conjugated network structure, as well as electron-rich thiophene building units, the SCMPs show better adsorption ability for iodine and a high uptake value of 222 wt % was obtained, which can compete with those nanoporous materials such as silver-containing zeolite, metal-organic frameworks (MOFs) and conjugated microporous polymers (CMPs), etc. Our study might provide a new possibility for the design and synthesis of functional CMPs containing electron-rich building units for effective capture and reversible storage of volatile iodine to address environmental issues.

  8. Three-dimensional microporous polypyrrole/polysulfone composite film electrode for supercapacitance performance

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojuan; Shi, Yanlong; Jin, Shuping

    2015-10-01

    The three-dimensional microporous polypyrrole/polysulfone (PPY/PSF) composite film was fabricated via a simple polymerization method. The morphology structure and chemical composition of the composite film were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The electrochemical properties of the composite film electrode were evaluated by cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. The material exhibits excellent capacitance performance including high capacitance of 500 F g-1 at 0.3 A g-1 current density, good cycle stability in 800 continuous cycles (only 4.5% decay after 800 cycles at 0.3 A g-1), and low inter resistance. The good property of the PPY/PSF electrode should be attributed to its structural features, including two-layer microporous structure which facilitates the penetration of electrolytes into the inner surface, high surface area which provides more active sites. These results show that the composite film is a promising candidate for high energy electrochemical capacitors.

  9. Interconnected, microporous hollow fibers for tissue engineering: commercially relevant, industry standard scale-up manufacturing.

    PubMed

    Tuin, Stephen A; Pourdeyhimi, Behnam; Loboa, Elizabeth G

    2014-09-01

    Significant progress has been achieved in the field of tissue engineering to create functional tissue using biomimetic three-dimensional scaffolds that support cell growth, proliferation, and extracellular matrix production. However, many of these constructs are severely limited by poor nutrient diffusion throughout the tissue-engineered construct, resulting in cell death and tissue necrosis at the core. Nutrient transport can be improved by creation and use of scaffolds with hollow and microporous fibers, significantly improving permeability and nutrient diffusion. The purpose of this review is to highlight current technological advances in the fabrication of hollow fibers with interconnected pores throughout the fiber walls, with specific emphasis on developing hollow porous nonwoven fabrics for use as tissue engineering constructs via industry standard processing technologies: Spunbond processing and polymer melt extrusion. We outline current methodologies to create hollow and microporous scaffolds with the aim of translating that knowledge to the production of such fibers into nonwoven tissue engineering scaffolds via spunbond technology, a commercially relevant and viable melt extrusion manufacturing approach that allows for facile scale-up.

  10. Pore-size dependence and characteristics of water diffusion in slitlike micropores

    SciTech Connect

    Diallo, S. O.

    2015-07-16

    The temperature dependence of the dynamics of water inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing pore size on the water dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (similar to 12 and 18 angstrom, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the water molecules is observed as the pore gap or temperature decreases. Suppression, we found, is accompanied by a systematic dependence of the average translational diffusion coefficient D-r and relaxation time [tau(0)] of the restricted water on pore size and temperature. We observed D-r values and tested against a proposed scaling law, in which the translational diffusion coefficient D-r of water within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient D-c associated with the water bound to the pore walls and the ratio theta of this strictly confined water to the total water inside the pore, yielding unique characteristic parameters for water transport in these carbon channels across the investigated temperature range.

  11. Pore-size dependence and characteristics of water diffusion in slitlike micropores

    DOE PAGES

    Diallo, S. O.

    2015-07-16

    The temperature dependence of the dynamics of water inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing pore size on the water dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (similar to 12 and 18 angstrom, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the water molecules is observed as the pore gap or temperature decreases. Suppression, we found, is accompanied by a systematic dependence of the average translational diffusion coefficient D-r and relaxation timemore » [tau(0)] of the restricted water on pore size and temperature. We observed D-r values and tested against a proposed scaling law, in which the translational diffusion coefficient D-r of water within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient D-c associated with the water bound to the pore walls and the ratio theta of this strictly confined water to the total water inside the pore, yielding unique characteristic parameters for water transport in these carbon channels across the investigated temperature range.« less

  12. Capture and Reversible Storage of Volatile Iodine by Novel Conjugated Microporous Polymers Containing Thiophene Units.

    PubMed

    Qian, Xin; Zhu, Zhao-Qi; Sun, Han-Xue; Ren, Feng; Mu, Peng; Liang, Weidong; Chen, Lihua; Li, An

    2016-08-17

    Conjugated microporous polymers having thiophene building blocks (SCMPs), which originated from ethynylbenzene monomers with 2,3,5-tribromothiophene, were designedly synthesized through Pd(0)/CuI catalyzed Sonogashira-Hagihara cross-coupling polymerization. The morphologies, structure and physicochemical properties of the as-synthesized products were characterized through scanning electron microscope (SEM), thermogravimeter analysis (TGA), (13)C CP/MAS solid state NMR and Fourier transform infrared spectroscope (FTIR) spectra. Nitrogen sorption-desorption analysis shows that the as-synthesized SCMPs possesses a high specific surface area of 855 m(2) g(-1). Because of their abundant porosity, π-conjugated network structure, as well as electron-rich thiophene building units, the SCMPs show better adsorption ability for iodine and a high uptake value of 222 wt % was obtained, which can compete with those nanoporous materials such as silver-containing zeolite, metal-organic frameworks (MOFs) and conjugated microporous polymers (CMPs), etc. Our study might provide a new possibility for the design and synthesis of functional CMPs containing electron-rich building units for effective capture and reversible storage of volatile iodine to address environmental issues. PMID:27458782

  13. Enhancement of Heat Transfer with Pool and Spray Impingement Boiling on Microporous and Nanowire Surface Coatings

    SciTech Connect

    Thiagarajan, S. J.; Wang, W.; Yang, R.; Narumanchi, S.; King, C.

    2010-09-01

    The DOE National Renewable Energy Laboratory (NREL) is leading a national effort to develop next-generation cooling technologies for hybrid vehicle electronics. The goal is to reduce the size, weight, and cost of power electronic modules that convert direct current from batteries to alternating current for the motor, and vice versa. Aggressive thermal management techniques help to increase power density and reduce weight and volume, while keeping chip temperatures within acceptable limits. The viability of aggressive cooling schemes such as spray and jet impingement in conjunction with enhanced surfaces is being explored. Here, we present results from a series of experiments with pool and spray boiling on enhanced surfaces, such as a microporous layer of copper and copper nanowires, using HFE-7100 as the working fluid. Spray impingement on the microporous coated surface showed an enhancement of 100%-300% in the heat transfer coefficient at a given wall superheat with respect to spray impingement on a plain surface under similar operating conditions. Critical heat flux also increased by 7%-20%, depending on flow rates.

  14. Injectable and microporous scaffold of densely-packed, growth factor-encapsulating chitosan microgels.

    PubMed

    Riederer, Michael S; Requist, Brennan D; Payne, Karin A; Way, J Douglas; Krebs, Melissa D

    2016-11-01

    In this work, an emulsion crosslinking method was developed to produce chitosan-genipin microgels which acted as an injectable and microporous scaffold. Chitosan was characterized with respect to pH by light scattering and aqueous titration. Microgels were characterized with swelling, light scattering, and rheometry of densely-packed microgel solutions. The results suggest that as chitosan becomes increasingly deprotonated above the pKa, repulsive forces diminish and intermolecular attractions cause pH-responsive chain aggregation; leading to microgel-microgel aggregation as well. The microgels with the most chitosan and least cross-linker showed the highest yield stress and a storage modulus of 16kPa when condensed as a microgel paste at pH 7.4. Two oppositely-charged growth factors could be encapsulated into the microgels and endothelial cells were able to proliferate into the 3D microgel scaffold. This work motivates further research on the applications of the chitosan microgel scaffold as an injectable and microporous scaffold in regenerative medicine. PMID:27516331

  15. Fabrication of microporous calcite block from calcium hydroxide compact under carbon dioxide atmosphere at high temperature.

    PubMed

    Otsu, Akihiro; Tsuru, Kanji; Maruta, Michito; Munar, Melvin L; Matsuya, Shigeki; Ishikawa, Kunio

    2012-01-01

    Effects of carbonation temperature and compacting pressure on basic properties of calcite block were studied using Ca(OH)2 compact made with 0.2-2.0 MPa and their carbonation at 200-800ºC for 1 h. Microporous calcite was obtained only when carbonated at 600ºC using Ca(OH)2 compact made with 0.2 MPa even though thermogravimetry analysis showed that calcite powder was stable up to 920ºC under CO2 atmosphere. CaO formed by carbonation at 700ºC and 800ºC is thought to be caused by the limited CO2 diffusion interior to the Ca(OH)2 compact. Also, unreacted Ca(OH)2 was found for Ca(OH)2 compact prepared with 0.5 MPa or higher pressure even when carbonated at 600ºC. As a result of high temperature carbonation, crystallite size of the calcite, 58.0 nm, was significantly larger when compared to that of calcite prepared at room temperature, 35.5 nm. Porosity and diametral tensile strength of the microporous calcite were 39.5% and 6.4 MPa. PMID:22864212

  16. Microporation and ‘Iron’ tophoresis for treating Iron deficiency anemia

    PubMed Central

    Modepalli, Naresh; Jo, Seongbong; Repka, Michael A.; Murthy, S. Narasimha

    2012-01-01

    Purpose Iontophoretic mediated transdermal delivery of ferric pyrophosphate (FPP) in combination with microneedle pretreatment was investigated as a potential treatment for iron deficiency anemia (IDA). Methods In vitro transdermal delivery studies were performed using hairless rat skin and pharmacodynamic studies were performed in hairless anemic rat model. The hematological and biochemical parameters like hemoglobin, hematocrit and % serum transferrin were monitored in rats at healthy, anemic condition and post treatment. Micropores created by the microneedles were visualized in histological skin sections after staining with hemotoxylin and eosin. The recovery of micropores was investigated in vivo by measuring Transepidermal water loss (TEWL) at different time points. Results The passive, microneedle and iontophoresis mediated delivery did not lead to significant improvement in hematological and biochemical parameters in anemic rats, when used individually. When iontophoresis (0.15 mA/cm2 for 4 hours) was combined with microneedle pretreatment (for 2 minutes), therapeutically adequate amount of FPP was delivered and there was significant recovery of rats from IDA. Conclusions Microneedle and iontophoresis mediated delivery of iron via transdermal route could be developed as a potential treatment for IDA. The transdermal controlled delivery of iron could become a potential, safe and effective alternative to parenteral iron therapy. PMID:23187864

  17. Activation of micropore-confined sulfur within hierarchical porous carbon for lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Joon; Kim, Hee Soo; Ahn, Jihoon; Lee, Kyung Jae; Yoo, Won Cheol; Sung, Yung-Eun

    2016-02-01

    Hierarchical porous carbon is often used in Li-S batteries due to the widely perceived benefits regarding the wide range of pore sizes. However, such notions are based solely on demonstrations of improved cyclic performances, and specific evidence to prove the utilization of the pores is yet to be found. Herein, we report, for the first time, the evidence for gradual activation of micropore-confined sulfur within porous carbon structures. By systematic comparison of microporous and hierarchical porous structures, we show that at sufficiently low current, sulfur infused hierarchical porous structures display a slowly activated and reversible reaction at 1.75 V vs Li/Li+ during discharge. This is in addition to the conventionally reported two voltage plateau at 2.3 and 2.1 V. Furthermore, the effects of LiNO3 decomposition on the system and the electrochemical mechanism behind the activation process is elucidated. Overall, the findings supplement the currently known electrochemical mechanisms occurring within porous structures and pave the way for more efficient utilization of hierarchical porous structures for applications in Li-S batteries.

  18. Kinetics of desorption of hexane from the microporous metal organic framework RPM-1

    SciTech Connect

    Smith, M.; Culp, J. T.; Bittner, E.; Parker, B.; Li, J.; Bockrath, B. C.

    2007-03-06

    The kinetics of desorption of hexane from the microporous metal framework RPM-1 has been studied using a pulse mass analyzer. In this method a small sample of organic liquid was injected into a heated carrier gas that passes through a packed bed of adsorbent. The change in mass of the bed with time was observed following the adsorption of the pulse. RPM-1 is a microporous material of the general formula [M3(bpdc)3(bpy)] · 4DMF · H2O, where M is either Co or Zn, bpdc is biphenyl dicarboxylate and bpy is 4,4'-bipyridine. The pores are channels of larger supercages (11 × 11 × 5 Å) connected by smaller windows of approximately 8 Å diameter. The desorption of hexane was well represented by a combination of two first order processes. Activation energies determined for the two processes over a temperature range of 373–473 K were 56 and 63 kJ/mol for RPM-1 (Co). The two activation energies are similar to isosteric heats of adsorption measured independently in earlier work at corresponding coverages. Similar values were found for RPM-1 (Zn). The pulse mass analyzer was found to be an effective way to investigate the dynamics of adsorption processes.

  19. Microporous organic polymer-based lithium ion batteries with improved rate performance and energy density

    NASA Astrophysics Data System (ADS)

    Zhang, Chong; Yang, Xiao; Ren, Wenfeng; Wang, Yanhong; Su, Fabing; Jiang, Jia-Xing

    2016-06-01

    Microporous organic polymers with triphenylamine segments were employed as cathode materials for lithium ion batteries. YPTPA with the highest surface area exhibits a discharge plateau at ∼3.6 V vs. Li/Li+, an initial Coulombic efficiency of 96.8% at 50 mA g-1 and a discharge capacity of 105.7 mAh g-1 at 200 mA g-1. Compared to the homo-coupled polymer of OPTPA with relatively low surface area (66 m2 g-1), SPTPA and YPTPA with higher surface area (544 and 1557 m2 g-1, respectively) show enhanced rate performances and energy densities. YPTPA can deliver 97.6 mAh g-1 within less than 3 min at high rate of 2000 mA g-1 and the energy density of 334 Wh kg-1 under an ultrahigh power density of 6816 W kg-1, while OPTPA only presents 48.2 mAh g-1 at 2000 mA g-1 with an energy density of 155 Wh kg-1 under 6414 W kg-1. The great improvement in electrochemical properties of SPTPA and YPTPA demonstrates that increasing surface area of polymer cathodes by interweaving the redox-active units into microporous polymer skeleton is an efficient way to develop advanced polymer cathode materials with outstanding electrochemical performance.

  20. Acidic and Hydrophobic Microporous Clays Pillared with Mixed Metal Oxide Nano-Sols

    NASA Astrophysics Data System (ADS)

    Han, Yang-Su; Yamanaka, Shoji; Choy, Jin-Ho

    1999-04-01

    Silica-metal oxide sol pillared clays have been synthesized from montmorillonite by exchanging interlamellar (Na+) ions with silica sol particles modified with polyhydroxy metal cations. Though the silica sol particle itself is negatively charged in the pH range used in present experiment, 1.5-2.7, the ion-exchange-type intercalation of the silica sol into montmorillonite was realized by modifying the surface charge of the sol particles from negative to positive. The positively charged silica sol particles were prepared by titrating metal aqueous solutions (Mz+=Fe3+, Al3+, Cr3+, and Zr4+) with NaOH in the presence of silica sol particles, which were easily intercalated inbetween the silicate layers of clay. On pillaring of oxide sols and subsequent calcining at 400°C, new porous materials were obtained with high BET surface areas of 320-720 m2/g, pore volumes of 0.24-0.50 ml/g, and basal spacings in the range 40-60 Å. Furthermore, their thermal stability could be remarkably improved up to 700°C. According to the adsorption measurements of nitrogen and solvent vapors, the micropores in the samples of size 9-13 Å dominate due to the multilayer stacking of interlayer sol particles inbetween silicate layers. Temperature-programmed desorption (TPD) spectra of ammonia revealed that the microporous samples are weakly acidic, but with different strengths, depending on the doped metal species.

  1. Percolation and diffusion in two-dimensional microporous media: Pillared clays

    NASA Astrophysics Data System (ADS)

    Chen, B. Y.; Kim, H.; Mahanti, S. D.; Pinnavaia, T. J.; Cai, Z. X.

    1994-03-01

    We have investigated the adsorptive and diffusive properties of N2, H2O, and rare gas atoms (Ar and He) in the pillared layered silicate clay systems [Cr(en)3+3]x[Co(en)3+2-(en)]1-x-L, where L is vermiculite (V), fluorohectorite (FHT), or montmorillonite (M), and (en) is an ethylenediamine ligand. In these mixed ion intercalates the intercalated [Cr(en)3+3] cation, where all three en ligands are coordinated to chromium, represents a laterally small pillaring agent, whereas [Co(en)3+2-en] represents a laterally large, ligand-dissociated species. Such systems are excellent models for two-dimensional microporous media. Adsorption measurements were carried out for N2, H2O, and Ar and diffusion studies were performed using simulation methods for both Ar and He. We find that the adsorptive and diffusive properties depend sensitively on the size of the diffusing species and the concentrations x and (1-x) of the intercalants. For Ar adsorption in the FHT system we observe a percolative response when x reaches 0.79. Using simple geometrical models to describe these microporous media, along with computer simulation, we can understand the x=0.79 percolation threshold. In addition, simulation studies of the relative diffusion rates of He and Ar for x=0 and 1, and comparison of these rates with experimental measurements by Zhou and Solin, suggest that He diffusion near narrow constrictions may be strongly suppressed by quantum effects.

  2. Capacitive Deionization using Biomass-based Microporous Salt-Templated Heteroatom-Doped Carbons.

    PubMed

    Porada, Slawomir; Schipper, Florian; Aslan, Mesut; Antonietti, Markus; Presser, Volker; Fellinger, Tim-Patrick

    2015-06-01

    Microporous carbons are an interesting material for electrochemical applications. In this study, we evaluate several such carbons without/with N or S doping with regard to capacitive deionization. For this purpose, we extent the salt-templating synthesis towards biomass precursors and S-doped microporous carbons. The sample with the largest specific surface area (2830 m(2)  g(-1) ) showed 1.0 wt % N and exhibited a high salt-sorption capacity of 15.0 mg g(-1) at 1.2 V in 5 mM aqueous NaCl. While being a promising material from an equilibrium performance point of view, our study also gives first insights to practical limitations of heteroatom-doped carbon materials. We show that high heteroatom content may be associated with a low charge efficiency. The latter is a key parameter for capacitive deionization and is defined as the ratio between the amounts of removed salt molecules and electrical charge.

  3. Pore-size dependence and characteristics of water diffusion in slitlike micropores

    NASA Astrophysics Data System (ADS)

    Diallo, S. O.

    2015-07-01

    The temperature dependence of the dynamics of water inside microporous activated carbon fibers (ACF) is investigated by means of incoherent elastic and quasielastic neutron-scattering techniques. The aim is to evaluate the effect of increasing pore size on the water dynamics in these primarily hydrophobic slit-shaped channels. Using two different micropore sizes (˜12 and 18 Å, denoted, respectively, ACF-10 and ACF-20), a clear suppression of the mobility of the water molecules is observed as the pore gap or temperature decreases. This suppression is accompanied by a systematic dependence of the average translational diffusion coefficient Dr and relaxation time <τ0> of the restricted water on pore size and temperature. The observed Dr values are tested against a proposed scaling law, in which the translational diffusion coefficient Dr of water within a porous matrix was found to depend solely on two single parameters, a temperature-independent translational diffusion coefficient Dc associated with the water bound to the pore walls and the ratio θ of this strictly confined water to the total water inside the pore, yielding unique characteristic parameters for water transport in these carbon channels across the investigated temperature range.

  4. Injectable and microporous scaffold of densely-packed, growth factor-encapsulating chitosan microgels.

    PubMed

    Riederer, Michael S; Requist, Brennan D; Payne, Karin A; Way, J Douglas; Krebs, Melissa D

    2016-11-01

    In this work, an emulsion crosslinking method was developed to produce chitosan-genipin microgels which acted as an injectable and microporous scaffold. Chitosan was characterized with respect to pH by light scattering and aqueous titration. Microgels were characterized with swelling, light scattering, and rheometry of densely-packed microgel solutions. The results suggest that as chitosan becomes increasingly deprotonated above the pKa, repulsive forces diminish and intermolecular attractions cause pH-responsive chain aggregation; leading to microgel-microgel aggregation as well. The microgels with the most chitosan and least cross-linker showed the highest yield stress and a storage modulus of 16kPa when condensed as a microgel paste at pH 7.4. Two oppositely-charged growth factors could be encapsulated into the microgels and endothelial cells were able to proliferate into the 3D microgel scaffold. This work motivates further research on the applications of the chitosan microgel scaffold as an injectable and microporous scaffold in regenerative medicine.

  5. Automated and inexpensive method to manufacture solid- state nanopores and micropores in robust silicon wafers

    NASA Astrophysics Data System (ADS)

    Vega, M.; Granell, P.; Lasorsa, C.; Lerner, B.; Perez, M.

    2016-02-01

    In this work an easy, reproducible and inexpensive technique for the production of solid state nanopores and micropores using silicon wafer substrate is proposed. The technique is based on control of pore formation, by neutralization etchant (KOH) with a strong acid (HCl). Thus, a local neutralization is produced around the nanopore, which stops the silicon etching. The etching process was performed with 7M KOH at 80°C, where 1.23µm/min etching speed was obtained, similar to those published in literature. The control of the pore formation with the braking acid method was done using 12M HCl and different extreme conditions: i) at 25°C, ii) at 80°C and iii) at 80°C applying an electric potential. In these studies, it was found that nanopores and micropores can be obtained automatically and at a low cost. Additionally, the process was optimized to obtain clean silicon wafers after the pore fabrication process. This method opens the possibility for an efficient scale-up from laboratory production.

  6. Development of microporous structure and its application to optical film for cellulose triacetate containing diisodecyl adipate.

    PubMed

    Shimada, Hikaru; Nobukawa, Shogo; Yamaguchi, Masayuki

    2015-04-20

    Phase separation in plasticized cellulose triacetate (CTA) films is investigated to produce a microporous film that can be used in optical devices. Hot-stretched CTA films containing diisodecyl adipate (DIDA) show negative orientation birefringence similar to the hot-stretched pure CTA. After extracting DIDA from the stretched films by immersion into an organic solvent, however, the films exhibit positive birefringence. Moreover, the magnitude of the birefringence increases with the wavelength, known as extraordinary dispersion, which is an essential property in the preparation of an ideal quarter-wave plate. Numerous ellipsoidal pores with micro-scale were detected in the film after the immersion, indicating that DIDA were segregated and formed ellipsoidal domains in the CTA matrix during annealing and stretching. These results indicate that extraordinary wavelength dispersion is given by the combinations of orientation birefringence from CTA and form birefringence from micropores. Furthermore, it was found that annealing time and stretching condition affect the phase separation as well as the shape and size of pores. PMID:25662683

  7. Embolization of experimental aneurysms using a heparin-loaded stent graft with micropores

    SciTech Connect

    Nishi, Shogo; Nakayama, Yasuhide; Ueda-Ishibashi, Hatsue; Matsuda, Takehisa

    2003-03-01

    Purpose: For percutaneous transluminal angioplasty (PTA), a heparin-loaded stent graft, composed of a commercially available metallic stent with a microporous and surface-modified thin film, has been developed. Early controlled endothelialization is promoted by a regular array of micropores produced by an excimer laser ablation technique. Early thrombus is prevented by a drug delivery system established by impregnation of photoreactive gelatin with heparin. Our stent grafts were used for embolization of experimental carotid aneurysms with an autologous external jugular vein patch in dogs. Materials and methods: At 1 month after formation, the aneurysms were occluded with stent grafts. Affected arteries were removed with the aneurysms, immediately (two aneurysms in one dog), 1 week (four aneurysms in two dogs), 1 month (three aneurysms in two dogs) and 3 months (four aneurysms in two dogs) after embolization, and were studied histologically to evaluate patency and endothelialization over the intraluminal surface of the thin film. Results: Treated carotid arteries were all patent with occluded aneurysms completely at any periods. Even at 1 week after embolization, endothelialization was confirmed on the surface of the stent graft on the lumen side. At 1 and 3 months, all treated aneurysms with enough patent parent arteries were filled with organized tissues and completely occluded. Conclusion: Our developed stent graft appears to be promising for the treatment of aneurysms, especially with respect to immediate termination of blood inflow and early endothelialization in the neck of the aneurysm.

  8. Accelerated wound healing by injectable microporous gel scaffolds assembled from annealed building blocks

    PubMed Central

    Griffin, Donald R.; Weaver, Westbrook M.; Scumpia, Philip; Di Carlo, Dino; Segura, Tatiana

    2015-01-01

    Summary Injectable hydrogels can provide a scaffold for in situ tissue regrowth and regeneration, however these injected materials require gel degradation prior to tissue reformation limiting their ability to provide physical support. We have created a new class of injectable biomaterial that circumvents this challenge by providing an interconnected microporous network for simultaneous tissue reformation and material degradation. We assemble monodisperse micro-gel building blocks into an interconnected microporous annealed particle (MAP) scaffold. Through microfluidic formation, we tailor the chemical and physical properties of the building blocks, providing downstream control of the physical and chemical properties of the assembled MAP scaffold. In vitro, cells incorporated during MAP scaffold formation proliferated and formed extensive 3D networks within 48 hours. In vivo, the injectable MAP scaffold facilitated cell migration resulting in rapid cutaneous tissue regeneration and tissue structure formation within 5 days. The combination of microporosity and injectability achieved with MAP scaffolds will enable novel routes to tissue regeneration in vivo and tissue creation de novo. PMID:26030305

  9. Effects of surface heterogeneity on the adsorption of CO₂ in microporous carbons.

    PubMed

    Liu, Yangyang; Wilcox, Jennifer

    2012-02-01

    Carbon capture combined with utilization and storage has the potential to serve as a near-term option for CO(2) emissions reduction. CO(2) capture by carbon-based sorbents and CO(2) storage in geologic formations such as coal and shale both require a thorough understanding of the CO(2) adsorption properties in microporous carbon-based materials. Complex pore structures for natural organic materials, such as coal and gas shale, in addition to general carbon-based porous materials are modeled as a collection of independent, noninterconnected, functionalized graphitic slit pores with surface heterogeneities. Electronic structure calculations coupled with van der Waals-inclusive corrections have been performed to investigate the electronic properties of functionalized graphitic surfaces. With Bader charge analysis, electronic structure calculations can provide the initial framework comprising both the geometry and corresponding charge information required to carry out statistical modeling. Grand canonical Monte Carlo simulations were carried out to determine the adsorption isotherms for a given adsorbent-adsorbate interaction at temperature/pressure conditions relevant to carbon capture applications to focus on the effect of the surface functionalities. On the basis of the current work, oxygen-containing functional groups were predicted to enhance CO(2) adsorption in microporous carbon materials in the absence of water vapor, and the hydrated graphite was found to hinder CO(2) adsorption. PMID:22216997

  10. A transverse isotropic model for microporous solids: Application to coal matrix adsorption and swelling

    NASA Astrophysics Data System (ADS)

    Espinoza, D. N.; Vandamme, M.; Dangla, P.; Pereira, J.-M.; Vidal-Gilbert, S.

    2013-12-01

    Understanding the adsorption-induced swelling in coal is critical for predictable and enhanced coal bed methane production. The coal matrix is a natural anisotropic disordered microporous solid. We develop an elastic transverse isotropic poromechanical model for microporous solids which couples adsorption and strain through adsorption stress functions and expresses the adsorption isotherm as a multivariate function depending on fluid pressure and solid strains. Experimental data from the literature help invert the anisotropic adsorptive-mechanical properties of Brzeszcze coal samples exposed to CO2. The main findings include the following: (1) adsorption-induced swelling can be modeled by including fluid-specific and pressure-dependent adsorption stress functions into equilibrium equations, (2) modeling results suggest that swelling anisotropy is mostly caused by anisotropy of the solid mechanical properties, and (3) the total amount of adsorbed gas measured by immersing coal in the adsorbate overestimates adsorption amount compared to in situ conditions up to ˜20%. The developed fully coupled model can be upscaled to determine the coal seam permeability through permeability-stress relationships.

  11. Acid gas scrubbing by composite solvent-swollen membranes

    DOEpatents

    Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

    1988-01-01

    A composite immobilized liquid membrane suitable for acid gas scrubbing is disclosed. The membrane is a solvent-swollen polymer and a microporous polymeric support, the solvent being selected from a class of highly polar solvents containing at least one atom selected from nitrogen, oxygen, phosphorous and sulfur, and having a boiling point of at least 100.degree. C. and a solubility parameter of from about 7.5 to about 13.5 (cal/cm.sup.3 -atm).sup.1/2. Such solvents are homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. Also disclosed are methods of acid gas scrubbing of high- and low-Btu gas effluents with such solvent-swollen membranes.

  12. Acid gas scrubbing by composite solvent-swollen membranes

    DOEpatents

    Matson, S.L.; Lee, E.K.L.; Friesen, D.T.; Kelly, D.J.

    1988-04-12

    A composite immobilized liquid membrane suitable for acid gas scrubbing is disclosed. The membrane is a solvent-swollen polymer and a microporous polymeric support, the solvent being selected from a class of highly polar solvents containing at least one atom selected from nitrogen, oxygen, phosphorus and sulfur, and having a boiling point of at least 100 C and a solubility parameter of from about 7.5 to about 13.5 (cal/cm[sup 3]-atm)[sup 1/2]. Such solvents are homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. Also disclosed are methods of acid gas scrubbing of high- and low-Btu gas effluents with such solvent-swollen membranes. 3 figs.

  13. A new multilayered composite hollow fiber membrane for artificial lung.

    PubMed

    Kamo, J; Uchida, M; Hirai, T; Yosida, H; Kamada, K; Takemura, T

    1990-10-01

    The gas transfer performances in a gas/membrane/liquid system were investigated in detail with various membranes. It was found that the oxygen flux in the gas/membrane/liquid system was saturated when the oxygen flux (Fg-g) in the gas/membrane/gas system became more than 1.0 x 10(-5) cm3 (STP) cm-2s-1cm Hg-1 (Fcg-g). This was explained as follows: The resistance of a boundary layer at liquid phase is dominant, i.e., the membrane resistance is negligible in the region of Fg-g which is greater than Fcg-g. Consequently, Fg-g of the membrane should be designed to be greater than Fcg-g, in order to satisfy the gas transfer performance required for blood oxygenation. On the basis of the results above, we have developed a new three-layered composite hollow fiber membrane (MHF) consisting of an ultrathin polyurethane layer supported between two microporous polyethylene layers to prevent serum leakage. It was shown through the evaluation in vitro that MHF had good gas transfer performances for long-term perfusion, and no serum leakage was observed. These characteristics suggest that MHF is quite suitable for long-term usage such as extracorporeal membrane oxygenation (ECMO). PMID:2241604

  14. 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

  15. 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

  16. Development of a membrane oxygenator for ECMO using a novel fine silicone hollow fiber.

    PubMed

    Funakubo, A; Higami, T; Sakuma, I; Fukui, Y; Kawamura, T; Sato, K; Sueoka, A; Nosé, Y

    1996-01-01

    One of the limitations of conventional silicone hollow fiber oxygenators compared with microporous membrane oxygenators is poor gas permeability. However, the silicone hollow fiber is free from plasma leakage, which is the major life limiting factor of the microporous membrane oxygenator. It has been difficult to fabricate a fine, thin hollow fiber for reduction of resistance to gas permeability because of the poor mechanical strength of conventional silicone materials. The authors developed a novel silicone material with sufficient mechanical strength, and a fine silicone hollow fiber with a diameter of 30 microns and wall thickness of 50 microns, which is approximately half that of a conventional silicone hollow fiber. Using this newly developed silicone hollow fiber, the authors developed a compact extracapillary flow membrane oxygenator. The oxygenator consists of fine silicone hollow fibers inserted in a housing made of polycarbonate. The housing is a cylindrical case, 20 cm long and 55 mm in inside diameter. The hollow fibers are cross-wound. The surface area of the membrane is 2.0 m2, and priming volume is 230 ml. Gas transfer performance of the newly developed oxygenator was evaluated by in vitro experiments. Oxygen and carbon dioxide transfer rates were 195 ml/min and 165 ml/min, at a blood flow rate 3 L/min. The novel silicone membrane oxygenator developed in this study can be used for extended duration in such applications as extracorporeal membrane oxygenation.

  17. 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.

  18. Charged membranes.

    PubMed

    Thatcher, Jack D

    2013-04-16

    This Teaching Resource provides three animated lessons that describe the storage and utilization of energy across plasma membranes. The "Na,K ATPase" animation explains how these pumps establish the electrochemical gradient that stores energy across plasma membranes. The "ATP synthesizing complexes" animation shows how these complexes transfer energy from the inner mitochondrial membrane to adenosine triphosphate (ATP). The "action potential" lesson explains how charged membranes are used to propagate signals along the axons of neurons. These animations serve as valuable resources for any collegiate-level course that describes these important factors. Courses that might employ them include introductory biology, biochemistry, biophysics, cell biology, pharmacology, and physiology.

  19. SEPARATION OF DILUTE ELECTROLYTES IN POLY(AMINO ACID) FUNCTIONALIZED MICROPOROUS MEMBRANES: MODEL EVALUATION AND EXPERIMENTAL RESULTS. (R829621)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  20. Surface glycosylation of polysulfone membrane towards a novel complexing membrane for boron removal.

    PubMed

    Meng, Jianqiang; Yuan, Jing; Kang, Yinlin; Zhang, Yufeng; Du, Qiyun

    2012-02-15

    In this study, a novel complexing membrane was synthesized for boron removal from aqueous solution. A glycopolymer, poly(2-gluconamidoethyl methacrylate) (PGAMA), was grafted onto the chloromethylated polysulfone (CMPSF) microporous membrane via surface-initiated ATRP (SIATRP). The glycosylated PSF (GlyPSF) membrane was characterized by attenuated total refection-Flourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM). It was demonstrated that PGAMA was successfully anchored onto the membrane surface and the grafting yield can be tuned in a wide range up to 5.9 mg/cm(2) by varying the polymerization time. The complexing membrane can adsorb boron rapidly with the equilibrium reached within 2h and has a remarkable high boron adsorption capacity higher than 2.0 mmol/g at optimized conditions. Freundlich, Langmuir, and Dubinin-Radushkevich adsorption isotherms were applied, and the data were best described by Langmuir model. Kinetic data were analyzed, and the data fitted very well to the pseudo-second-order rate expression. The optimal pH for boron uptake is in a wide range of 6-9, and the optimal initial boron concentration is over 300 mg/L. Studies of ionic strength effects indicated the formation of inner-sphere surface complexes. The complexed boron can be leached quantitatively under acid condition.

  1. Fluorescent nanoparticles based on a microporous organic polymer network: fabrication and efficient energy transfer to surface-bound dyes.

    PubMed

    Patra, Abhijit; Koenen, Jan-Moritz; Scherf, Ullrich

    2011-09-14

    Well-defined nanoparticles composed of a tetraphenylmethane-based microporous polymer network with an average particle diameter of 30-60 nm were fabricated by a miniemulsion polymerization technique. Strong green emission was observed and efficient excitation energy transfer from nanoparticles to surface-bound dye molecules was explored. PMID:21805006

  2. Core-shell conjugated microporous polymers: a new strategy for exploring color-tunable and -controllable light emissions.

    PubMed

    Xu, Yanhong; Nagai, Atsushi; Jiang, Donglin

    2013-02-25

    A core-shell strategy is demonstrated for designing a conjugated microporous polymer that allows the tuning of light emission over a wide wavelength range in a controlled manner. The polymers not only emit efficiently with an eight-fold enhanced luminescence but also sustain light emissions, irrespective of solvent and state.

  3. Rapid biofabrication of tubular tissue constructs by centrifugal casting in a decellularized natural scaffold with laser-machined micropores.

    PubMed

    Kasyanov, Vladimir A; Hodde, Jason; Hiles, Michael C; Eisenberg, Carol; Eisenberg, Leonard; De Castro, Luis E F; Ozolanta, Iveta; Murovska, Modra; Draughn, Robert A; Prestwich, Glenn D; Markwald, Roger R; Mironov, Vladimir

    2009-01-01

    Centrifugal casting allows rapid biofabrication of tubular tissue constructs by suspending living cells in an in situ cross-linkable hydrogel. We hypothesize that introduction of laser-machined micropores into a decellularized natural scaffold will facilitate cell seeding by centrifugal casting and increase hydrogel retention, without compromising the biomechanical properties of the scaffold. Micropores with diameters of 50, 100, and 200 mum were machined at different linear densities in decellularized small intestine submucosa (SIS) planar sheets and tubular SIS scaffolds using an argon laser. The ultimate stress and ultimate strain values for SIS sheets with laser-machined micropores with diameter 50 mum and distance between holes as low as 714 mum were not significantly different from unmachined control SIS specimens. Centrifugal casting of GFP-labeled cells suspended in an in situ cross-linkable hyaluronan-based hydrogel resulted in scaffold recellularization with a high density of viable cells inside the laser-machined micropores. Perfusion tests demonstrated the retention of the cells encapsulated within the HA hydrogel in the microholes. Thus, an SIS scaffold with appropriately sized microholes can be loaded with hydrogel encapsulated cells by centrifugal casting to give a mechanically robust construct that retains the cell-seeded hydrogel, permitting rapid biofabrication of tubular tissue construct in a "bioreactor-free" fashion.

  4. Micropore diffusion in coal chars under reactive conditions: Annual topical report, 15 September 1987--15 September 1988

    SciTech Connect

    Calo, J.M.; Perkins, M.T.; Lilly, W.D.

    1988-01-01

    The current project is concerned with the development and application of a new technique to measure micropore diffusion under actual gasification conditions. The method is an outgrowth of and related to the transient kinetics approach to the measurement of kinetic rate parameters for char-gas reactions that has been developed in our laboratory. It can be shown that the initial transient behavior of a species introduced as a step-function into a ''gradientless'' reactor in which char is present, is controlled by the transport resistance offered by the char micropores. Therefore, this data can be analyzed for micropore diffusion time constants. In addition, due to the time-resolved nature of the process in the reactor, the initial diffusion step is separated (in time) from any subsequent gas-solid reaction steps. Therefore, diffusion measurements can be performed under gasification conditions. Diffusion time constant data have been obtained for a few microporous carbonaceous materials, including a Sigma (pine wood) char, a Fischer coconut char and PSOC-467 (Deadman No. 2) subbituminous coal char, in addition to the previously reported (DOE/PC/90529-Annual-1) 5A zeolite data. These data have been compared to other results, where possible, and, for the most part, they behave as expected. 65 refs., 12 figs.

  5. Kagomé type extra-large microporous solid based on a paddle-wheel Cu2+ dimer.

    PubMed

    Horike, Satoshi; Hasegawa, Shinpei; Tanaka, Daisuke; Higuchi, Masakazu; Kitagawa, Susumu

    2008-10-01

    A robust extra-large microporous coordination polymer with a Kagomé type structure was synthesized by carboxylate/amine multifunctional ligand with a Cu2+ cluster and the hexagonal 1D channels (approximately 15 A) showed type I and IV adsorption isotherms for gas molecules.

  6. Synthesis of Two-dimensional Microporous Carbonaceous Polymer Nanosheets and Their Application as High-performance CO2 Capture Sorbent.

    PubMed

    Zhang, Miao; Liu, Lin; He, Teng; Wu, Guotao; Chen, Ping

    2016-06-21

    The synthesis of two-dimensional (2D) polymer nanosheets with a well-defined microporous structure remains challenging in materials science. Here, a new kind of 2D microporous carbonaceous polymer nanosheets was synthesized through polymerization of a very low concentration of 1,4-dicyanobenzene in molten zinc chloride at 400-500 °C. This type of nanosheets has a thickness in the range of 3-20 nm, well-defined microporosity, a high surface area (∼537 m(2)  g(-1) ), and a large micropore volume (∼0.45 cm(3)  g(-1) ). The microporous carbonaceous polymer nanosheets exhibit superior CO2 sorption capability (8.14 wt % at 298 K and 1 bar) and a relatively high CO2 selectivity toward N2 (25.6). Starting from different aromatic nitrile monomers, a variety of 2D carbonaceous polymer nanosheets can be obtained showing a certain universality of the ionothermal method reported herein.

  7. Super liquid-repellent gas membranes for carbon dioxide capture and heart-lung machines.

    PubMed

    Paven, Maxime; Papadopoulos, Periklis; Schöttler, Susanne; Deng, Xu; Mailänder, Volker; Vollmer, Doris; Butt, Hans-Jürgen

    2013-01-01

    In a gas membrane, gas is transferred between a liquid and a gas through a microporous membrane. The main challenge is to achieve a high gas transfer while preventing wetting and clogging. With respect to the oxygenation of blood, haemocompatibility is also required. Here we coat macroporous meshes with a superamphiphobic-or liquid repellent-layer to meet this challenge. The superamphiphobic layer consists of a fractal-like network of fluorinated silicon oxide nanospheres; gas trapped between the nanospheres keeps the liquid from contacting the wall of the membrane. We demonstrate the capabilities of the membrane by capturing carbon dioxide gas into a basic aqueous solution and in addition use it to oxygenate blood. Usually, blood tends to clog membranes because of the abundance of blood cells, platelets, proteins and lipids. We show that human blood stored in a superamphiphobic well for 24 h can be poured off without leaving cells or adsorbed protein behind.

  8. Super liquid-repellent gas membranes for carbon dioxide capture and heart–lung machines

    PubMed Central

    Paven, Maxime; Papadopoulos, Periklis; Schöttler, Susanne; Deng, Xu; Mailänder, Volker; Vollmer, Doris; Butt, Hans-Jürgen

    2013-01-01

    In a gas membrane, gas is transferred between a liquid and a gas through a microporous membrane. The main challenge is to achieve a high gas transfer while preventing wetting and clogging. With respect to the oxygenation of blood, haemocompatibility is also required. Here we coat macroporous meshes with a superamphiphobic—or liquid repellent—layer to meet this challenge. The superamphiphobic layer consists of a fractal-like network of fluorinated silicon oxide nanospheres; gas trapped between the nanospheres keeps the liquid from contacting the wall of the membrane. We demonstrate the capabilities of the membrane by capturing carbon dioxide gas into a basic aqueous solution and in addition use it to oxygenate blood. Usually, blood tends to clog membranes because of the abundance of blood cells, platelets, proteins and lipids. We show that human blood stored in a superamphiphobic well for 24 h can be poured off without leaving cells or adsorbed protein behind. PMID:24065073

  9. Hollow Fiber Spacesuit Water Membrane Evaporator Development and Testing for Advanced Spacesuits

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Trevino, Luis; Tsioulos, Gus; Settles, Joseph; Colunga, Aaron; Vogel, Matthew; Vonau, Walt

    2010-01-01

    Grant Bue and Matthew Vogel presented the two types of Spacesuit Water Membrane Evaporators (SWME) that were developed based on hydrophobic microporous membranes. One type, the Sheet Membrane (SaM) SWME, is composed of six concentric Teflon sheet membranes fixed on cylindrical-supporting screens to form three concentric annular water channels. Those water channels are surrounded by vacuum passages to draw off the water vapor that passes through the membrane. The other type, the Hollow Fiber (HoFi) SWME, is composed of more than 14,000 tubes. Water flows through the tubes and water vapor passes through the tube wall to the shell side that vents to the vacuum of space. Both SWME types have undergone testing to baseline the performance at predicted operating temperatures and flow rates; the units also have been subjected to contamination testing and other conditions to test resiliency.

  10. Synthetic Two-Dimensional Materials: A New Paradigm of Membranes for Ultimate Separation.

    PubMed

    Zheng, Zhikun; Grünker, Ronny; Feng, Xinliang

    2016-08-01

    Microporous membranes act as selective barriers and play an important role in industrial gas separation and water purification. The permeability of such membranes is inversely proportional to their thickness. Synthetic two-dimensional materials (2DMs), with a thickness of one to a few atoms or monomer units are ideal candidates for developing separation membranes. Here, groundbreaking advances in the design, synthesis, processing, and application of 2DMs for gas and ion separations, as well as water desalination are presented. This report describes the syntheses, structures, and mechanical properties of 2DMs. The established methods for processing 2DMs into selective permeation membranes are also discussed and the separation mechanism and their performances addressed. Current challenges and emerging research directions, which need to be addressed for developing next-generation separation membranes, are summarized. PMID:27214781

  11. Separating Oil-Water Nanoemulsions using Flux-Enhanced Hierarchical Membranes

    PubMed Central

    Solomon, Brian R.; Hyder, Md. Nasim; Varanasi, Kripa K.

    2014-01-01

    Membranes that separate oil-water mixtures based on contrasting wetting properties have recently received significant attention. Separation of nanoemulsions, i.e. oil-water mixtures containing sub-micron droplets, still remains a key challenge. Tradeoffs between geometric constraints, high breakthrough pressure for selectivity, high flux, and mechanical durability make it challenging to design effective membranes. In this paper, we fabricate a hierarchical membrane by the phase inversion process that consists of a nanoporous separation skin layer supported by an integrated microporous layer. We demonstrate the separation of water-in-oil emulsions well below 1 μm in size. In addition, we tune the parameters of the hierarchical membrane fabrication to control the skin layer thickness and increase the total flux by a factor of four. These simple yet robust hierarchical membranes with engineered wetting characteristics show promise for large-scale, efficient separation systems. PMID:24980852

  12. Synthetic Two-Dimensional Materials: A New Paradigm of Membranes for Ultimate Separation.

    PubMed

    Zheng, Zhikun; Grünker, Ronny; Feng, Xinliang

    2016-08-01

    Microporous membranes act as selective barriers and play an important role in industrial gas separation and water purification. The permeability of such membranes is inversely proportional to their thickness. Synthetic two-dimensional materials (2DMs), with a thickness of one to a few atoms or monomer units are ideal candidates for developing separation membranes. Here, groundbreaking advances in the design, synthesis, processing, and application of 2DMs for gas and ion separations, as well as water desalination are presented. This report describes the syntheses, structures, and mechanical properties of 2DMs. The established methods for processing 2DMs into selective permeation membranes are also discussed and the separation mechanism and their performances addressed. Current challenges and emerging research directions, which need to be addressed for developing next-generation separation membranes, are summarized.

  13. A Nd:YAG Laser-microperforated poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-basal Membrane Matrix Composite film as Substrate for Keratinocytes

    SciTech Connect

    Serrano,F.; Lopez, L.; Jadraque, M.; Koper, M.; Ellis, G.; Cano, P.; Martin, M.; Garrido, L.

    2007-01-01

    Epithelia cultured for the treatment of ulcers, burns and for gene therapy applications require a flexible biomaterial for growth and transplantation that is adaptable to body contours. We tested several materials and found that a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) polyester provided support for keratinocytes, although adhesion to this material proved to be suboptimal. Since epithelia adhere to the mesoderm through basal membranes, we engineered a basal membrane surrogate by preparing composites of PHBHV with basal membrane matrix (BMM). To allow cell migration into injuried areas the polyester film was micromachined to insert high-density micropores through a Nd:YAG laser ablation process. These flexible composites provided firm attachment for keratinocytes from the outer root sheath of human hair allowing keratinocyte migration through micropores. Films of microperforated PHBHV-BMM may be of use for the replacement of diseased or injured skin epithelia.

  14. A Nd:YAG laser-microperforated poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-basal membrane matrix composite film as substrate for keratinocytes.

    PubMed

    Serrano, Fernando; López-G, Laura; Jadraque, Maria; Koper, Mariëlle; Ellis, Gary; Cano, Pilar; Martín, Margarita; Garrido, Leoncio

    2007-02-01

    Epithelia cultured for the treatment of ulcers, burns and for gene therapy applications require a flexible biomaterial for growth and transplantation that is adaptable to body contours. We tested several materials and found that a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) polyester provided support for keratinocytes, although adhesion to this material proved to be suboptimal. Since epithelia adhere to the mesoderm through basal membranes, we engineered a basal membrane surrogate by preparing composites of PHBHV with basal membrane matrix (BMM). To allow cell migration into injuried areas the polyester film was micromachined to insert high-density micropores through a Nd:YAG laser ablation process. These flexible composites provided firm attachment for keratinocytes from the outer root sheath of human hair allowing keratinocyte migration through micropores. Films of microperforated PHBHV-BMM may be of use for the replacement of diseased or injured skin epithelia. PMID:17027945

  15. Nanoporous silicon nitride membranes fabricated from porous nanocrystalline silicon templates

    NASA Astrophysics Data System (ADS)

    Desormeaux, J. P. S.; Winans, J. D.; Wayson, S. E.; Gaborski, T. R.; Khire, T. S.; Striemer, C. C.; McGrath, J. L.

    2014-08-01

    The extraordinary permeability and manufacturability of ultrathin silicon-based membranes are enabling devices with improved performance and smaller sizes in such important areas as molecular filtration and sensing, cell culture, electroosmotic pumping, and hemodialysis. Because of the robust chemical and mechanical properties of silicon nitride (SiN), several laboratories have developed techniques for patterning nanopores in SiN using reactive ion etching (RIE) through a template structure. These methods however, have failed to produce pores small enough for ultrafiltration (<100 nm) in SiN and involve templates that are prone to microporous defects. Here we present a facile, wafer-scale method to produce nanoporous silicon nitride (NPN) membranes using porous nanocrystalline silicon (pnc-Si) as a self-assembling, defect free, RIE masking layer. By modifying the mask layer morphology and the RIE etch conditions, the pore sizes of NPN can be adjusted between 40 nm and 80 nm with porosities reaching 40%. The resulting NPN membranes exhibit higher burst pressures than pnc-Si membranes while having 5× greater permeability. NPN membranes also demonstrate the capacity for high resolution separations (<10 nm) seen previously with pnc-Si membranes. We further demonstrate that human endothelial cells can be grown on NPN membranes, verifying the biocompatibility of NPN and demonstrating the potential of this material for cell culture applications.

  16. Biofouling and microbial communities in membrane distillation and reverse osmosis.

    PubMed

    Zodrow, Katherine R; Bar-Zeev, Edo; Giannetto, Michael J; Elimelech, Menachem

    2014-11-18

    Membrane distillation (MD) is an emerging desalination technology that uses low-grade heat to drive water vapor across a microporous hydrophobic membrane. Currently, little is known about the biofilms that grow on MD membranes. In this study, we use estuarine water collected from Long Island Sound in a bench-scale direct contact MD system to investigate the initial stages of biofilm formation. For comparison, we studied biofilm formation in a bench-scale reverse osmosis (RO) system using the same feedwater. These two membrane desalination systems expose the natural microbial community to vastly different environmental conditions: high temperatures with no hydraulic pressure in MD and low temperature with hydraulic pressure in RO. Over the course of 4 days, we observed a steady decline in bacteria concentration (nearly 2 orders of magnitude) in the MD feed reservoir. Even with this drop in planktonic bacteria, significant biofilm formation was observed. Biofilm morphologies on MD and RO membranes were markedly different. MD membrane biofilms were heterogeneous and contained several colonies, while RO membrane biofilms, although thicker, were a homogeneous mat. Phylogenetic analysis using next-generation sequencing of 16S rDNA showed significant shifts in the microbial communities. Bacteria representing the orders Burkholderiales, Rhodobacterales, and Flavobacteriales were most abundant in the MD biofilms. On the basis of the results, we propose two different regimes for microbial community shifts and biofilm development in RO and MD systems. PMID:25295386

  17. Biofouling and microbial communities in membrane distillation and reverse osmosis.

    PubMed

    Zodrow, Katherine R; Bar-Zeev, Edo; Giannetto, Michael J; Elimelech, Menachem

    2014-11-18

    Membrane distillation (MD) is an emerging desalination technology that uses low-grade heat to drive water vapor across a microporous hydrophobic membrane. Currently, little is known about the biofilms that grow on MD membranes. In this study, we use estuarine water collected from Long Island Sound in a bench-scale direct contact MD system to investigate the initial stages of biofilm formation. For comparison, we studied biofilm formation in a bench-scale reverse osmosis (RO) system using the same feedwater. These two membrane desalination systems expose the natural microbial community to vastly different environmental conditions: high temperatures with no hydraulic pressure in MD and low temperature with hydraulic pressure in RO. Over the course of 4 days, we observed a steady decline in bacteria concentration (nearly 2 orders of magnitude) in the MD feed reservoir. Even with this drop in planktonic bacteria, significant biofilm formation was observed. Biofilm morphologies on MD and RO membranes were markedly different. MD membrane biofilms were heterogeneous and contained several colonies, while RO membrane biofilms, although thicker, were a homogeneous mat. Phylogenetic analysis using next-generation sequencing of 16S rDNA showed significant shifts in the microbial communities. Bacteria representing the orders Burkholderiales, Rhodobacterales, and Flavobacteriales were most abundant in the MD biofilms. On the basis of the results, we propose two different regimes for microbial community shifts and biofilm development in RO and MD systems.

  18. Membrane-Based Water Evaporator for a Space Suit

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; McCann, Charles J.; O'Connell, Mary K.; Andrea, Scott

    2004-01-01

    A membrane-based water evaporator has been developed that is intended to serve as a heat-rejection device for a space suit. This evaporator would replace the current sublimator that is sensitive to contamination of its feedwater. The design of the membrane-based evaporator takes advantage of recent advances in hydrophobic micropore membranes to provide robust heat rejection with much less sensitivity to contamination. The low contamination sensitivity allows use of the heat transport loop as feedwater, eliminating the need for the separate feedwater system used for the sublimator. A cross section of the evaporator is shown in the accompanying figure. The space-suit cooling loop water flows into a distribution plenum, through a narrow annulus lined on both sides with a hydrophobic membrane, into an exit plenum, and returns to the space suit. Two perforated metal tubes encase the membranes and provide structural strength. Evaporation at the membrane inner surface dissipates the waste heat from the space suit. The water vapor passes through the membrane, into a steam duct and is vented to the vacuum environment through a back-pressure valve. The back-pressure setting can be adjusted to regulate the heat-rejection rate and the water outlet temperature.

  19. Hyper-parallel tempering Monte Carlo simulations of Ar adsorption in new models of microporous non-graphitizing activated carbon: effect of microporosity

    NASA Astrophysics Data System (ADS)

    Terzyk, Artur P.; Furmaniak, Sylwester; Gauden, Piotr A.; Harris, Peter J. F.; Wloch, Jerzy; Kowalczyk, Piotr

    2007-10-01

    The adsorption of gases on microporous carbons is still poorly understood, partly because the structure of these carbons is not well known. Here, a model of microporous carbons based on fullerene-like fragments is used as the basis for a theoretical study of Ar adsorption on carbon. First, a simulation box was constructed, containing a plausible arrangement of carbon fragments. Next, using a new Monte Carlo simulation algorithm, two types of carbon fragments were gradually placed into the initial structure to increase its microporosity. Thirty six different microporous carbon structures were generated in this way. Using the method proposed recently by Bhattacharya and Gubbins (BG), the micropore size distributions of the obtained carbon models and the average micropore diameters were calculated. For ten chosen structures, Ar adsorption isotherms (87 K) were simulated via the hyper-parallel tempering Monte Carlo simulation method. The isotherms obtained in this way were described by widely applied methods of microporous carbon characterisation, i.e. Nguyen and Do, Horvath-Kawazoe, high-resolution αs plots, adsorption potential distributions and the Dubinin-Astakhov (DA) equation. From simulated isotherms described by the DA equation, the average micropore diameters were calculated using empirical relationships proposed by different authors and they were compared with those from the BG method.

  20. Reactive melt infiltration of silicon-molybdenum alloys into microporous carbon preforms

    NASA Technical Reports Server (NTRS)

    Singh, M.; Behrendt, D. R.

    1995-01-01

    Investigations on the reactive melt infiltration of silicon-1.7 and 3.2 at.% molybdenum alloys into microporous carbon preforms have been carried out by modeling, differential thermal analysis (DTA), and melt infiltration experiments. These results indicate that the pore volume fraction of the carbon preform is a very important parameter in determining the final composition of the reaction-formed silicon carbide and the secondary phases. Various undesirable melt infiltration results, e.g. choking-off, specimen cracking, silicon veins, and lake formation, and their correlation with inadequate preform properties are presented. The liquid silicon-carbon reaction exotherm temperatures are influenced by the pore and carbon particle size of the preform and the compositions of infiltrants. Room temperature flexural strength and fracture toughness of materials made by the silicon-3.2 at.% molybdenum alloy infiltration of medium pore size preforms are also discussed.

  1. Accelerated wound healing by injectable microporous gel scaffolds assembled from annealed building blocks

    NASA Astrophysics Data System (ADS)

    Griffin, Donald R.; Weaver, Westbrook M.; Scumpia, Philip O.; di Carlo, Dino; Segura, Tatiana

    2015-07-01

    Injectable hydrogels can provide a scaffold for in situ tissue regrowth and regeneration, yet gel degradation before tissue reformation limits the gels' ability to provide physical support. Here, we show that this shortcoming can be circumvented through an injectable, interconnected microporous gel scaffold assembled from annealed microgel building blocks whose chemical and physical properties can be tailored by microfluidic fabrication. In vitro, cells incorporated during scaffold formation proliferated and formed extensive three-dimensional networks within 48 h. In vivo, the scaffolds facilitated cell migration that resulted in rapid cutaneous-tissue regeneration and tissue-structure formation within five days. The combination of microporosity and injectability of these annealed gel scaffolds should enable novel routes to tissue regeneration and formation in vivo.

  2. Novel thiophene-bearing conjugated microporous polymer honeycomb-like porous spheres with ultrahigh iodine uptake.

    PubMed

    Ren, Feng; Zhu, Zhaoqi; Qian, Xin; Liang, Weidong; Mu, Peng; Sun, Hanxue; Liu, Jiehua; Li, An

    2016-07-28

    Two conjugated microporous polymers containing thiophene-moieties (SCMPs) were obtained by the polymerization of 3,3',5,5'-tetrabromo-2,2'-bithiophene and ethynylbenzene monomers through the palladium-catalyzed Sonogashira-Hagihara crosscoupling reaction. The resulting SCMPs show high thermal stability with a decomposition temperature above 300 °C. Scanning electron microscopy images show that the resulting SCMPs formed as an aggregation composed of micrometer-sized SCMP spheres, in which honeycomb-like porous spheres with penetrated pores on the surface were observed. Taking advantage of such a unique honeycomb-like porous morphology as well as π-conjugated structures, the SCMPs show ultrahigh absorption performance for iodine vapour with an uptake of up to 345 wt% obtained, which is the highest value reported to date for CMPs, thus making the resulting SCMPs ideal absorbent materials for reversible iodine capture to address environmental issues. PMID:27417941

  3. Fractional diffusion interpretation of simulated single-file systems in microporous materials.

    PubMed

    Demontis, Pierfranco; Suffritti, Giuseppe B

    2006-11-01

    The single-file diffusion of water in the straight channels of two different crystalline microporous aluminosilicates (zeolites bikitaite and Li-ABW) was studied by comparing the results of molecular dynamics computer simulations with the predictions of anomalous diffusion theory modeled by using fractional diffusion equations. At high coverage, the agreement is reasonably good, in particular for sufficiently large displacements and sufficiently long times. At low coverage, interesting phenomena appear in the simulation results, such as multimodal propagators, which could be interpreted on the basis of fractional Fokker-Planck equations. The results are discussed also in view of different theories that have been proposed to model the single-file diffusion process.

  4. Thermochemistry of organic reactions in microporous oxides by atomistic simulations: benchmarking against periodic B3LYP.

    PubMed

    Bleken, Francesca; Svelle, Stian; Lillerud, Karl Petter; Olsbye, Unni; Arstad, Bjørnar; Swang, Ole

    2010-07-15

    The methylation of ethene by methyl chloride and methanol in the microporous materials SAPO-34 and SSZ-13 has been studied using different periodic atomistic modeling approaches based on density functional theory. The RPBE functional, which earlier has been used successfully in studies of surface reactions on metals, fails to yield a qualitatively correct description of the transition states under study. Employing B3LYP as functional gives results in line with experimental data: (1) Methanol is adsorbed more strongly than methyl chloride to the acid site. (2) The activation energies for the methylation of ethene are slightly lower for SSZ-13. Furthermore, the B3LYP activation energies are lower for methyl chloride than for methanol. PMID:20557090

  5. Microporous polyvinylidene fluoride film with dense surface enables efficient piezoelectric conversion

    NASA Astrophysics Data System (ADS)

    Chen, Dajing; Zhang, John X. J.

    2015-05-01

    We demonstrate that asymmetric porous polyvinylidene fluoride (PVDF) film, with pores mostly distributed in the bulk but not at the surfaces, can be used as a highly efficient piezoelectric energy generation device. For such microporous PVDF film with dense or pore-free surface, piezoelectric theory shows the efficiency of energy conversion by piezoelectric device depends upon the structure compressibility. Film mechanical properties can be controlled by dispersing micro-scale pores in a polymer matrix with a dense top layer. Piezoelectric output is enhanced by optimization of PVDF micro-structure and electromechanical coupling efficiency. The power output increased three folds with a designed three-dimensional asymmetric porous structure as compared to solid film.

  6. Fabrication of Microporous Corundum-Spinel Refractory Castables by Foam-Gelcasting Methods

    NASA Astrophysics Data System (ADS)

    Chen, Huan; Liang, Feng; Fang, Wei; Chen, Hui; Du, Xing; Wang, Fucheng; Zhao, Lei

    2015-08-01

    Microporous corundum-spinel castables with high strength and low thermal conductivity have been fabricated by foam-gelcasting methods. A systematical investigation on different properties of samples, such as porosity, pore size distribution, thermal conductivity, cold modulus of rupture, and cold crushing strength has been taken in this paper, and scanning electron microscopy (SEM) was used to characterize the microstructure of samples. Results show that the average pore size increases correspondingly when the content of foaming agent increases from 0 to 2.0 wt.%. It was found that when the content of the foaming agent is up to 1.5 wt.%, the thermal conductivity, cold modulus of rupture, and cold crushing strength of samples were 0.751 W/mK at 1000 °C, 30.5, and 136 MPa, respectively.

  7. Surface texture and percolation effects in microporous oriented films of polyolefins

    NASA Astrophysics Data System (ADS)

    Novikov, D. V.; Kuryndin, I. S.; Bukošek, V.; Elyashevich, G. K.

    2012-11-01

    The surface structure of polypropylene and polyethylene microporous films prepared by the extrusion of the polymer melt with the subsequent stages of annealing, uniaxial extension, and thermal fixation of the samples has been analyzed using scanning electron microscopy. It has been shown that percolation through pores corresponds to the axial texture of the surface with the channel structure described by the fractal cluster model. The transition from open pores (through-flow channels) to closed pores leads to the formation of surface regions with a biaxial texture. An increase in the density of the solid phase cluster is accompanied by the formation of a homogeneous biaxial texture with a period of alternation of the density in two mutually perpendicular directions, one of which coincides with the direction of orientation of the films.

  8. Low-pressure argon adsorption assessment of micropore connectivities in activated carbons.

    PubMed

    Zimny, T; Villieras, F; Finqueneisel, G; Cossarutto, L; Weber, J V

    2006-01-01

    Low-pressure argon adsorption has been used to study the energetic distribution of microporous activated carbons differing by their burn-off. The collected isotherms were analyzed using the derivative isotherm summation method. Some oscillations on the experimental curves for very low partial pressures were detected. The results are analyzed and discussed according to the literature and could be attributed to local overheating caused by spontaneous mass transfer of argon through constrictions between former pores and the new opening pore or deadend pores. We used the dynamic character of the experimental method and mainly the discrepancy of the quasi-equilibrium state to deduce key parameters related to the porosity topology. PMID:16112680

  9. Analytic theory of two-dimensional NMR in systems with coupled macro- and micropores.

    PubMed

    Johnson, David Linton; Schwartz, Lawrence M

    2014-09-01

    Two-dimensional (2D) nuclear magnetic resonance (NMR) experiments involve a sequence of longitudinal (T(1)) and transverse (T(2)) measurements. When such experiments are applied to porous media, they are believed to provide new and important information regarding diffusive coupling between distinct pore subpopulations. However, we show in this paper that, in many cases of interest, this is simply not true. One often encounters systems in which the one-dimensional (1D) T(1) and T(2) processes are each controlled by just two distinct decay modes. If these modes form a complete set, then one can derive analytic formulas that describe, exactly, the 2D NMR measurements. Therefore, for such systems, the 2D measurements bring no additional information over that which is already present in the 1D results. Our predictions agree quite well with numerical results based on the microporous grain-consolidation (μ-GC) model. PMID:25314457

  10. Microporous Polymers from a Carbazole-Based Triptycene Monomer: Synthesis and Their Applications for Gas Uptake.

    PubMed

    Zhai, Tian-Long; Tan, Liangxiao; Luo, Yi; Liu, Jun-Min; Tan, Bien; Yang, Xiang-Liang; Xu, Hui-Bi; Zhang, Chun

    2016-01-01

    Two kinds of novel organic microporous polymers TCPs (TCP-A and TCP-B) were prepared by two cost-effective synthetic strategies from the monomer of tricarbazolyltriptycene (TCT). Their structure and properties were characterized by FT-IR, solid (13) C NMR, powder XRD, SEM, TEM, and gas absorption measurements. TCP-B displayed a high surface area (1469 m(2)  g(-1) ) and excellent H2 storage (1.70 wt % at 1 bar/77 K) and CO2 uptake abilities (16.1 wt % at 1 bar/273 K), which makes it a promising material for potential application in gas storage.

  11. Effect of nanoparticle coating on the thermal conductivity of microporous thermal insulations.

    PubMed

    Lee, Dong-Bok; Kwon, Hyuk-Chon; Kim, Yun-Il; Park, Sung; Lee, Jae Chun; Misture, Scott

    2010-05-01

    Microporous thermal insulations were prepared from mixtures of nano-sized fumed silica, micron-sized fibers and opacifier particles. Those micron-sized particles were dry coated with nano-sized fumed silica particles by mechanical process using a compressive-shear type mill. The effect of nanoparticle coating on the thermal conductivity of the insulation media was investigated using a hot-wire method. Effect of nanoparticle coating was found to be more pronounced for the insulation composed of fumed silica and fiber than for the one composed of fumed silica, fiber and an opacifier. By adding 15% SiC or TiO2 opacifier, the thermal conductivity of the insulation samples could be lowered to 0.08 Wm(-1) K(-1) at temperature range of 805 approximately 817 degrees C. The temperature dependent thermal conductivity of the sample containing glass fiber did not exhibit any remarkable changes compared to the one containing ceramic fiber.

  12. Divalent Fe Atom Coordination in Two-Dimensional Microporous Graphitic Carbon Nitride.

    PubMed

    Oh, Youngtak; Hwang, Jin Ok; Lee, Eui-Sup; Yoon, Minji; Le, Viet-Duc; Kim, Yong-Hyun; Kim, Dong Ha; Kim, Sang Ouk

    2016-09-28

    Graphitic carbon nitride (g-C3N4) is a rising two-dimensional material possessing intrinsic semiconducting property with unique geometric configuration featuring superimposed heterocyclic sp(2) carbon and nitrogen network, nonplanar layer chain structure, and alternating buckling. The inherent porous structure of heptazine-based g-C3N4 features electron-rich sp(2) nitrogen, which can be exploited as a stable transition metal coordination site. Multiple metal-functionalized g-C3N4 systems have been reported for versatile applications, but local coordination as well as its electronic structure variation upon incoming metal species is not well understood. Here we present detailed bond coordination of divalent iron (Fe(2+)) through micropore sites of graphitic carbon nitride and provide both experimental and computational evidence supporting the aforementioned proposition. In addition, the utilization of electronic structure variation is demonstrated through comparative photocatalytic activities of pristine and Fe-g-C3N4.

  13. UV-Visible and Plasmonic Nanospectroscopy of the CO2 Adsorption Energetics in a Microporous Polymer.

    PubMed

    Nugroho, Ferry A A; Xu, Chao; Hedin, Niklas; Langhammer, Christoph

    2015-10-20

    In the context of carbon capture and storage (CCS), micro- and mesoporous polymers have received significant attention due to their ability to selectively adsorb and separate CO2 from gas streams. The performance of such materials is critically dependent on the isosteric heat of adsorption (Qst) of CO2 directly related to the interaction strength between CO2 and the adsorbent. Here, we show using the microporous polymer PIM-1 as a model system that its Qst can be conveniently determined by in situ UV-vis optical transmission spectroscopy directly applied on the adsorbent or, with higher resolution, by indirect nanoplasmonic sensing based on localized surface plasmon resonance in metal nanoparticles. Taken all together, this study provides a general blueprint for efficient optical screening of micro- and mesoporous polymeric materials for CCS in terms of their CO2 adsorption energetics and kinetics.

  14. Microporous aluminophosphate nanosheets and their nanomorphic zeolite analogues tailored by hierarchical structure-directing amines.

    PubMed

    Seo, Yongbeom; Lee, Sungjune; Jo, Changbum; Ryoo, Ryong

    2013-06-19

    Multiamines with amphiphilic structures have been synthesized to serve as simultaneous structure-directing agents in micro- and meso-structural levels for aluminophosphate materials (AlPOs) and their analogues, such as silicoaluminophosphate, cobalt aluminophosphate, and gallium phosphate. The amine molecules are assembled into a micelle with a specific morphology to function as a meso-level structure director. Individual amine groups in the micelle are able to direct the formation of microporous crystalline AlPO structure. The resultant meso-level morphologies of the AlPOs are typically nanosheets of uniform thickness, which can be tailored in the range of 2-5 nm by the number of amine groups. Sponge-like disordered mesoporous morphologies can be generated, depending on the amine structures. Using such multiamines provides a versatile route to various phosphate materials with a structural hierarchy for enhanced porous functionalities. PMID:23731379

  15. Molding mineral within microporous hydrogels by a polymer-induced liquid-precursor (PILP) process.

    PubMed

    Cheng, Xingguo; Gower, Laurie B

    2006-01-01

    Natural biominerals often have exquisite morphologies, where the cells exercise a high degree of crystallographic control through secretion of biological macromolecules and regulation of ion transport. One important example is the sea urchin spine. It has recently been shown to be formed through deposition of a transient amorphous calcium carbonate (ACC) precursor phase that later transforms to single-crystalline calcite, ultimately forming an elaborate three-dimensional microporous calcium carbonate structure with interconnected pores. Macromolecules associated with the mineral phase are thought to play a key role in regulating this transformation. The work described here mimics this type of morphological control by "molding" an amorphous calcium carbonate precursor within a porous poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel that has been prepared as a negative replica from the void space of an urchin spine. Using an acidic biomimetic polymer as a process-directing agent, we show that polyaspartic acid induces amorphous calcium carbonate (ACC) nanoparticles, which have fluidic character and therefore are able to infiltrate the PHEMA hydrogel replica and coalesce into the convoluted morphology that replicates the original microporous structure of the sea urchin spine. By "molding" calcium carbonate into a complex morphology at room temperature, using a precursor process that is induced by a biomimetic acidic macromolecule, the PILP process is a useful in vitro model for examining different aspects of the amorphous-to-crystalline transformation process that is apparently used by a variety of biomineralizing organisms. For example, although we were able to replicate the overall morphology of the spine, it had polycrystalline texture; further studies with this system will focus on controlling the nucleation event, which may help to elucidate how such a convoluted structure can be prepared with single-crystalline texture via an amorphous precursor. Through a

  16. Acoustic and reservoir properties of microporous carbonate rocks: Implication of micrite particle size and morphology

    NASA Astrophysics Data System (ADS)

    Regnet, J. B.; Robion, P.; David, C.; Fortin, J.; Brigaud, B.; Yven, B.

    2015-02-01

    This integrated study provides significant insight into parameters controlling the acoustic and reservoir properties of microporous limestones, improving the knowledge of the relationships among petrophysic and microstructural content. Petrophysical properties measured from laboratory and logging tools (porosity, permeability, electrical conductivity, and acoustic properties) have been coupled with thin section and scanning electron microscope observations on the EST205 borehole from the Oxfordian limestone aquifer of the eastern part of the Paris Basin. A major achievement is the establishment of the link between micrite microtexture types (particle morphology and nature of intercrystal contacts) and the physical response, introducing a new effective and interesting rock-typing approach for microporous reservoirs. Fluid-flow properties are enhanced by the progressive augmentation of intercrystalline microporosity and associated pore throat diameter, as the coalescence of micrite particles decreases. Concerning acoustic properties, the slow increase of P wave velocity can be seen as a reflection of crystal size and growing contact cementation leading to a more cohesive and stiffer micrite microtexture. By applying poroelasticity theory on our samples, we show that velocity dispersion can be a very useful tool for data discrimination in carbonates. This dispersion analysis highlights the presence of microcracks in the rocks, and their overall effect on acoustic and transport properties. The presence of microcracks is also confirmed with observations and permeability measurements under high confining pressure. Finally, a possible origin of high porous levels in neritic limestones is a mineralogical transformation of carbonates through freshwater-related diagenesis during subaerial exposure time. Finally, by applying poroelasticity theory on our samples, we show that velocity dispersion can be a very useful tool for data discrimination in carbonates.

  17. Effect of microporation on passive and iontophoretic delivery of diclofenac sodium.

    PubMed

    Patel, Hiren; Joshi, Abhay; Joshi, Amit; Stagni, Grazia

    2015-01-01

    Skin pretreatment with a microneedle roller (microporation (MP)) appears a simple and inexpensive technique to increase transdermal delivery of topically applied drug products. This study investigates the effect of MP on the passive and iontophoretic delivery of diclofenac (DCF) by quantifying dermis and plasma levels of DCF in a rabbit model. New Zealand albino female rabbits received either: (i) a topical application of 4 g of Voltaren® 1% gel with or without pretreatment with a microroller (0.5 mm needle length; density 23 microneedles per cm(2) area) or (ii) a DCF solution (40 mg/2.5 mL) via iontophoresis (IOMED transQ(E) medium size patch), with or without microroller pretreatment. A 300 µA/cm(2) cathodic current was applied for 20 min for a total of 80 mA. DCF concentrations were monitored in dermis with microdialysis sampling every 20 min for 5 h. Plasma samples were collected over the same period. In the passive delivery studies, microroller pretreatment increased Cmax by 1.5- and 2.0-fold in skin and plasma, respectively, and AUC by 1.5- and 2.4-fold in skin and plasma, respectively. In the iontophoresis delivery studies, microporation increased Cmax by 2.0-fold both in skin and in plasma, and AUC by 1.1- and 1.8-fold in skin and plasma, respectively. In conclusion, microneedle pretreatment increased significantly the systemic exposure of DCF from either passive or iontophoretic delivery, whereas the effect in skin was less pronounced.

  18. Surface acoustic wave technique for the characterization of porous properties of microporous silicate thin films

    NASA Astrophysics Data System (ADS)

    Hietala, Susan Leslie

    1997-12-01

    Features of gas adsorption onto sol-gel derived microporous silicate thin films, for characterization of porous properties, are detailed using a surface acoustic wave (SAW) technique. Mass uptake and film effective modulus changes calculated from the SAW data are investigated in detail. The effects of stress and surface tension on the SAW sensor are calculated and found to be negligible in these experiments. Transient behavior recorded during nitrogen adsorption at 77 K is discussed in the context of mass uptake and effective modulus contributions. The time constant associated with the effective modulus calculation is consistent with that of diffusivity of nitrogen into a 5A zeolite. Further calculations indicate that the transient behavior is not due to thermal effects. A unique dual sensor SAW experiment to decouple the mass and effective modulus contributions to the frequency response was performed in conjunction with a Silicon beam-bending experiment. The beam-bending experiment results in a calculation of stress induced during adsorption of methanol on a microporous silicate thin film. The decoupled mass and effective modulus calculated from the SAW data have similar shaped isotherms, and are quite different from that of the stress developed in the Silicon beam. The total effective modulus change calculated from the SAW data is consistent with that calculated using Gassmann's equation. The SAW system developed for this work included unique electronics and customized hardware which is suitable for work under vacuum and at temperatures from 77K to 473K. This unique setup is suitable for running thin film samples on a Micromeritics ASAP 2000 Gas Adsorption unit in automatic mode. This setup is also general enough to be compatible with a custom gas adsorption unit and the beam bending apparatus, both using standard vacuum assemblies.

  19. SiC-BASED HYDROGEN SELECTIVE MEMBRANES FOR WATER-GAS-SHIFT REACTION

    SciTech Connect

    Paul K.T. Liu

    2001-10-16

    This technical report summarizes our activities conducted in Yr II. In Yr I we successfully demonstrated the feasibility of preparing the hydrogen selective SiC membrane with a chemical vapor deposition (CVD) technique. In addition, a SiC macroporous membrane was fabricated as a substrate candidate for the proposed SiC membrane. In Yr II we have focused on the development of a microporous SiC membrane as an intermediate layer between the substrate and the final membrane layer prepared from CVD. Powders and supported thin silicon carbide films (membranes) were prepared by a sol-gel technique using silica sol precursors as the source of silicon, and phenolic resin as the source of carbon. The powders and films were prepared by the carbothermal reduction reaction between the silica and the carbon source. The XRD analysis indicates that the powders and films consist of SiC, while the surface area measurement indicates that they contain micropores. SEM and AFM studies of the same films also validate this observation. The powders and membranes were also stable under different corrosive and harsh environments. The effects of these different treatments on the internal surface area, pore size distribution, and transport properties, were studied for both the powders and the membranes using the aforementioned techniques and XPS. Finally the SiC membrane materials are shown to have satisfactory hydrothermal stability for the proposed application. In Yr III, we will focus on the demonstration of the potential benefit using the SiC membrane developed from Yr I and II for the water-gas-shift (WGS) reaction.

  20. Membrane-on-a-chip: microstructured silicon/silicon-dioxide chips for high-throughput screening of membrane transport and viral membrane fusion.

    PubMed

    Kusters, Ilja; van Oijen, Antoine M; Driessen, Arnold J M

    2014-04-22

    Screening of transport processes across biological membranes is hindered by the challenge to establish fragile supported lipid bilayers and the difficulty to determine at which side of the membrane reactants reside. Here, we present a method for the generation of suspended lipid bilayers with physiological relevant lipid compositions on microstructured Si/SiO2 chips that allow for high-throughput screening of both membrane transport and viral membrane fusion. Simultaneous observation of hundreds of single-membrane channels yields statistical information revealing population heterogeneities of the pore assembly and conductance of the bacterial toxin α-hemolysin (αHL). The influence of lipid composition and ionic strength on αHL pore formation was investigated at the single-channel level, resolving features of the pore-assembly pathway. Pore formation is inhibited by a specific antibody, demonstrating the applicability of the platform for drug screening of bacterial toxins and cell-penetrating agents. Furthermore, fusion of H3N2 influenza viruses with suspended lipid bilayers can be observed directly using a specialized chip architecture. The presented micropore arrays are compatible with fluorescence readout from below using an air objective, thus allowing high-throughput screening of membrane transport in multiwell formats in analogy to plate readers.

  1. A Solvent-Free Surface Suspension Melt Technique for Making Biodegradable PCL Membrane Scaffolds for Tissue Engineering Applications.

    PubMed

    Suntornnond, Ratima; An, Jia; Tijore, Ajay; Leong, Kah Fai; Chua, Chee Kai; Tan, Lay Poh

    2016-01-01

    In tissue engineering, there is limited availability of a simple, fast and solvent-free process for fabricating micro-porous thin membrane scaffolds. This paper presents the first report of a novel surface suspension melt technique to fabricate a micro-porous thin membrane scaffolds without using any organic solvent. Briefly, a layer of polycaprolactone (PCL) particles is directly spread on top of water in the form of a suspension. After that, with the use of heat, the powder layer is transformed into a melted layer, and following cooling, a thin membrane is obtained. Two different sizes of PCL powder particles (100 µm and 500 µm) are used. Results show that membranes made from 100 µm powders have lower thickness, smaller pore size, smoother surface, higher value of stiffness but lower ultimate tensile load compared to membranes made from 500 µm powder. C2C12 cell culture results indicate that the membrane supports cell growth and differentiation. Thus, this novel membrane generation method holds great promise for tissue engineering. PMID:27007364

  2. Effects of ultrathin silicone coating of porous membrane on gas transfer and hemolytic performance.

    PubMed

    Niimi, Y; Ueyama, K; Yamaji, K; Yamane, S; Tayama, E; Sueoka, A; Kuwana, K; Tahara, K; Nosé, Y

    1997-10-01

    To assess the effect of an ultrathin (0.2 microm) silicone-coated microporous membrane oxygenator on gas transfer and hemolytic performance, a silicone-coated capillary membrane oxygenator (Mera HP Excelung-prime, HPO-20H-C, Senko Medical Instrument Mfg. Co., Ltd., Tokyo, Japan) was compared with a noncoated polypropylene microporous membrane oxygenator of the same model and manufacturer using an in vitro test circuit. The 2 oxygenators showed little difference in the oxygen (O2) transfer rate over a wide range of blood flow rates (1 L/min to 8 L/min). The carbon dioxide (CO2) transfer rate was almost the same in both devices at low blood flow rates, but the silicone-coated oxygenator showed a decrease of more than 20% in the CO2 transfer rate at higher blood flow rates. This loss in performance could be partly attenuated by increasing the gas/blood flow ratio from 0.5 or 1.0 to 2.0. In the hemolysis study, the silicone-coated membrane oxygenator showed a smaller increase in plasma free hemoglobin than the noncoated oxygenator. The pressure drop across both oxygenators was the same. These results suggest that the ultrathin silicone-coated porous membrane oxygenator may be a useful tool for long-term extracorporeal lung support while maintaining a sufficient gas transfer rate and causing less blood component damage.

  3. 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.

  4. Investigation of gas diffusion layer compression by electrochemical impedance spectroscopy on running polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Dotelli, Giovanni; Omati, Luca; Gallo Stampino, Paola; Grassini, Paolo; Brivio, Davide

    Two gas diffusion layers based on the same carbon cloth substrate, produced by an Italian Company (SAATI), and coated with microporous layers of different hydrophobicities, were assembled in a polymer electrolyte membrane fuel cell and its performances assessed. For comparison the cell mounting the carbon cloth without microporous layer was also tested. The membrane electrode assembly was made of Nafion ® 212 with Pt load 0.3/0.6 mg cm -2 (anode/cathode). The cell testing was run at 60 °C and 80 °C with fully humidified air (100%RH) and 80%RH hydrogen feedings. The assembly of gas diffusion layers and membrane with electrodes was compressed to 30% and 50% of its initial thickness. For each configuration polarization and power curves were recorded; in order to evaluate the role of different GDLs, AC impedance spectroscopy of the running cell was also performed. The higher compression ratio caused the worsening of cell performances, partially mitigated when the operating temperature was raised to 80 °C. The presence of the microporous layer onto the carbon cloth resulted extremely beneficial for the operations especially at high current density; moreover, it sensibly reduces the high frequency resistance of the overall assembly.

  5. Adult Books for Young Adults.

    ERIC Educational Resources Information Center

    Carter, Betty

    1997-01-01

    Considers the differences between young adult and adult books and maintains that teachers must be familiar with young adults' tastes for both. Suggests that traffic between these publishing divisions is a two-way street, with young adults reading adult books and adults reading young adult books. (TB)

  6. 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

  7. Membrane Nanotubes

    NASA Astrophysics Data System (ADS)

    Derényi, I.; Koster, G.; van Duijn, M. M.; Czövek, A.; Dogterom, M.; Prost, J.

    There is a growing pool of evidence showing the biological importance of membrane nanotubes (with diameter of a few tens of nanometers and length upto tens of microns) in various intra- and intercellular transport processes. These ubiquitous structures are often formed from flat membranes by highly localized forces generated by either the pulling of motor proteins or the pushing of polymerizing cytoskeletal filaments. In this chapter we give an overview of the theory of membrane nanotubes, their biological relevance, and the most recent experiments designed for the study of their formation and dynamics. We also discuss the effect of membrane proteins or lipid composition on the shape of the tubes, and the effect of antagonistic motor proteins on tube formation.

  8. Performance of Multiple Risk Assessment Tools to Predict Mortality for Adult Respiratory Distress Syndrome with Extracorporeal Membrane Oxygenation Therapy: An External Validation Study Based on Chinese Single-center Data

    PubMed Central

    Huang, Lei; Li, Tong; Xu, Lei; Hu, Xiao-Min; Duan, Da-Wei; Li, Zhi-Bo; Gao, Xin-Jing; Li, Jun; Wu, Peng; Liu, Ying-Wu; Wang, Song; Lang, Yu-Heng

    2016-01-01

    Background: There has been no external validation of survival prediction models for severe adult respiratory distress syndrome (ARDS) with extracorporeal membrane oxygenation (ECMO) therapy in China. The aim of study was to compare the performance of multiple models recently developed for patients with ARDS undergoing ECMO based on Chinese single-center data. Methods: A retrospective case study was performed, including twenty-three severe ARDS patients who received ECMO from January 2009 to July 2015. The PRESERVE (Predicting death for severe ARDS on VV-ECMO), ECMOnet, Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) score, a center-specific model developed for inter-hospital transfers receiving ECMO, and the classical risk-prediction scores of Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) were calculated. In-hospital and six-month mortality were regarded as the endpoints and model performance was evaluated by comparing the area under the receiver operating characteristic curve (AUC). Results: The RESP and APACHE II scores showed excellent discriminate performance in predicting survival with AUC of 0.835 (95% confidence interval [CI], 0.659–1.010, P = 0.007) and 0.762 (95% CI, 0.558–0.965, P = 0.035), respectively. The optimal cutoff values were risk class 3.5 for RESP and 35.5 for APACHE II score, and both showed 70.0% sensitivity and 84.6% specificity. The excellent performance of these models was also evident for the pneumonia etiological subgroup, for which the SOFA score was also shown to be predictive, with an AUC of 0.790 (95% CI, 0.571–1.009, P = 0.038). However, the ECMOnet and the score developed for externally retrieved ECMO patients failed to demonstrate significant discriminate power for the overall cohort. The PRESERVE model was unable to be evaluated fully since only one patient died six months postdischarge. Conclusions: The RESP, APCHAE II, and SOFA scorings

  9. Vacuum membrane distillation by microchip with temperature gradient.

    PubMed

    Zhang, Yaopeng; Kato, Shinji; Anazawa, Takanori

    2010-04-01

    A multilayered microchip (25 x 95 mm) used for vacuum distillation is designed, fabricated and tested by rectification of a water-methanol mixture. The polymer chip employs a cooling channel to generate a temperature gradient along a distillation channel below, which is separated into a channel (72 microm deep) for liquid phase and a channel (72 microm deep) for vapor phase by an incorporated microporous poly(tetrafluoroethylene) (PTFE) membrane. The temperature gradient is controlled by adjusting hotplate temperature and flow rate of cooling water to make the temperatures in the stripping section higher than the increasing boiling points of the water-enriched liquids and the temperatures in the rectifying section lower than the decreasing dew points of the methanol-enriched vapors. The effects of temperature gradient, feed composition, feed flow rate and membrane pore size on the micro distillation are also investigated. A theoretical plate number up to 1.8 is achieved at the optimum conditions. PMID:20300677

  10. Extraction of molybdenum by a supported liquid membrane method.

    PubMed

    Basualto, Carlos; Marchese, José; Valenzuela, Fernando; Acosta, Adolfo

    2003-04-10

    This is a report on the extraction of molybdenum(VI) ions using a supported liquid membrane, prepared by dissolving in kerosene, the extractant Alamine 336 (a long-chain tertiary amine) employed as mobile carrier. A flat hydrophobic microporous membrane was utilised as solid support. Appropriate conditions for Mo(VI) extraction through the liquid membrane were obtained from the results of liquid-liquid extraction and stripping partition experiments. The influence of feed solution acidity, the carrier extractant concentration in the organic liquid film and the content of strip agent on the metal flux through membrane were investigated. It was established that maximal extraction of metal is achieved at a pH 2.0 if sulphuric acid is used in the feed solution and at a pH value over 11.0 if Na(2)CO(3) is used as strip agent. Moreover, the molybdenum extraction through membrane is enhanced when a 0.02 mol l(-1) content of the amine carrier in the organic phase is used. The present paper deals with an equilibrium investigation of the extraction of Mo(VI) by Alamine 336 and its permeation conditions through the liquid membrane, and examines a possible mechanism of extraction.

  11. Eggplant-derived microporous carbon sheets: towards mass production of efficient bifunctional oxygen electrocatalysts at low cost for rechargeable Zn-air batteries.

    PubMed

    Li, Bing; Geng, Dongsheng; Lee, Xinjing Shannon; Ge, Xiaoming; Chai, Jianwei; Wang, Zhijuan; Zhang, Jie; Liu, Zhaolin; Hor, T S Andy; Zong, Yun

    2015-05-25

    We report 2D microporous carbon sheets with high surface area, derived from eggplant via simple carbonization and KOH activation, as low cost yet efficient bifunctional catalysts for high performance rechargeable zinc-air batteries.

  12. Eggplant-derived microporous carbon sheets: towards mass production of efficient bifunctional oxygen electrocatalysts at low cost for rechargeable Zn-air batteries.

    PubMed

    Li, Bing; Geng, Dongsheng; Lee, Xinjing Shannon; Ge, Xiaoming; Chai, Jianwei; Wang, Zhijuan; Zhang, Jie; Liu, Zhaolin; Hor, T S Andy; Zong, Yun

    2015-05-25

    We report 2D microporous carbon sheets with high surface area, derived from eggplant via simple carbonization and KOH activation, as low cost yet efficient bifunctional catalysts for high performance rechargeable zinc-air batteries. PMID:25920952

  13. Light-emitting conjugated polymers with microporous network architecture: interweaving scaffold promotes electronic conjugation, facilitates exciton migration, and improves luminescence.

    PubMed

    Xu, Yanhong; Chen, Long; Guo, Zhaoqi; Nagai, Atsushi; Jiang, Donglin

    2011-11-01

    Herein we report a strategy for the design of highly luminescent conjugated polymers by restricting rotation of the polymer building blocks through a microporous network architecture. We demonstrate this concept using tetraphenylethene (TPE) as a building block to construct a light-emitting conjugated microporous polymer. The interlocked network successfully restricted the rotation of the phenyl units, which are the major cause of fluorescence deactivation in TPE, thus providing intrinsic luminescence activity for the polymers. We show positive "CMP effects" that the network promotes π-conjugation, facilitates exciton migration, and improves luminescence activity. Although the monomer and linear polymer analogue in solvents are nonemissive, the network polymers are highly luminescent in various solvents and the solid state. Because emission losses due to rotation are ubiquitous among small chromophores, this strategy can be generalized for the de novo design of light-emitting materials by integrating the chromophores into an interlocked network architecture.

  14. Ozone treatment of coal- and coffee grounds-based active carbons: Water vapor adsorption and surface fractal micropores

    SciTech Connect

    Tsunoda, Ryoichi; Ozawa, Takayoshi; Ando, Junichi

    1998-09-15

    Characteristics of the adsorption iostherms of water vapor on active carbons from coal and coffee grounds and those ozonized ones from the surface fractal dimension analysis are discussed. The upswing of the adsorption isotherms in the low relative pressure of coffee grounds-based active carbon, of which isotherms were not scarcely affected on ozonization, was attributed to the adsorption of water molecules on the metallic oxides playing the role of oxygen-surface complexes, which formed the corrugated surfaces on the basal planes of micropore walls with the surface fractal dimension D{sub s} > 2. On the other hand, coal-based active carbon with D{sub s} < 2, which indicated the flat surfaces of micropore walls, showed little effect on the upswing even on ozonization, even though the adsorption amounts of water vapor were increased in the low relative pressure.

  15. Membrane air stripping: A process for removal of organics from aqueous solutions

    SciTech Connect

    Mahmud, H.; Kumar, A.; Narbaitz, R.M.; Matsuura, T.

    1998-10-01

    The membrane air-stripping (MAS) process using microporous polypropylene hollow fiber membranes has shown potential for the removal of volatile organics from aqueous streams over conventional treatment processes, particularly in reducing the size of the equipment. This paper reviews the theoretical aspects and experimental investigations on the performance of these membranes in terms of overall mass transfer capabilities in the removal of organics from aqueous solutions. The reported findings of the effect of pH, ozone, chlorine, influence of packing density and possible fouling on the performance of these hollow fibers membranes are presented. The fate of the stripped air is discussed. Other possible applications as well as the future research needs are highlighted, along with critical assessment of the reported work.

  16. Selectivity characteristics of potentiometric carbon dioxide sensors with various gas membrane materials

    SciTech Connect

    Kobos, R.K.; Parks, S.J.; Meyerhoff, M.E.

    1982-10-01

    The selectivity characteristics of potentiometric carbon dioxide sensors with regard to various organic and inorganic acid interferences have been systematically examined. When used in conjunction with a standard silicone rubber CO/sub 2/ permeable membrane, the sensor displays surprisingly large response to several organic acids having low volatility, e.g., benzoic, cinnamic, and salicylic acids. If the outer membrane is changed to a microporous Teflon material, the response to these substances is diminished, but poor selectivity over volatile organics and acidic gases results. The use of a new homogeneous Teflon-like membrane meterial is shown to offer dramatic improvement in selectivity for CO/sub 2/ over all of the compounds tested. The mechanistic reasons for this enhanced selectivity are discussed as are alternate methods for reducing organic acid interferences when using more conventional membrane materials. 4 figures, 1 table.

  17. Structure and properties of ITQ-8: a hydrous layer silicate with microporous silicate layers.

    PubMed

    Marler, Bernd; Müller, Melanie; Gies, Hermann

    2016-06-21

    ITQ-8 is a new hydrous layer silicate (HLS) with a chemical composition of [C4H8(C7H13N)2]8 [Si64O128(OH)16]·48H2O per unit cell. The synthesis of ITQ-8 was first described in 2002 by Díaz-Cabañas et al., the structure of this material, however, remained unsolved at that time. Physico-chemical characterization using solid-state NMR spectroscopy, SEM, TG-DTA, and FTIR spectroscopy confirmed that ITQ-8 is a layer silicate. The XRD powder pattern was indexed in the monoclinic system with lattice parameters of a0 = 35.5168(5) Å, b0 = 13.3989(2) Å, c0 = 16.0351(2) Å, β = 106.74(2)°. The crystal structure was solved by simulated annealing. Rietveld refinement of the structure in space group C2/c converged to residual values of RBragg = 0.023, RF = 0.022 and chi(2) = 2.3 confirming the structure model. The structure of ITQ-8 contains silicate layers with a topology that resembles a (11-1) section of the framework of zeolite levyne. So far, this layer topology is unique among layer silicates. The layer can be regarded as made up of 4-, 6-, double-six and 8-rings which are interconnected to form cup-like "half-cages". Unlike other HLSs, which possess impermeable silicate layers, ITQ-8 contains 8-rings pores with a free diameter of 3.5 Å × 3.4 Å and can be regarded as a "small-pore layer silicate". In the crystal structure, the organic cations, 1,4-diquiniclidiniumbutane, used as structure directing agents during synthesis are intercalated between the silicate layers. Clusters (bands) of water molecules which are hydrogen bonded to each other and to the terminal Si-OH/Si-O(-) groups are located between the organic cations and interconnect the silicate layers. ITQ-8 is a very interesting material as precursor for the synthesis of microporous framework silicates by topotactic condensation or interlayer expansion reactions leading to 3D micro-pore systems which may be useful in applications as e.g. catalysts, catalyst supports and adsorbents of for separation. PMID

  18. Fabrication of GaN Microporous Structure at a GaN/Sapphire Interface as the Template for Thick-Film GaN Separation Grown by HVPE

    NASA Astrophysics Data System (ADS)

    Chen, Jianli; Cheng, Hongjuan; Zhang, Song; Lan, Feifei; Qi, Chengjun; Xu, Yongkuan; Wang, Zaien; Li, Jing; Lai, Zhanping

    2016-10-01

    In this paper, a microporous structure at the GaN/sapphire interface has been obtained by an electrochemical etching method via a selective etching progress using an as-grown GaN/sapphire wafer grown by metal organic chemical vapor deposition. The as-prepared GaN interfacial microporous structure has been used as a template for the following growth of thick-film GaN crystal by hydride vapor phase epitaxy (HVPE), facilitating the fabrication of a free-standing GaN substrate detached from a sapphire substrate. The evolution of the interfacial microporous structure has been investigated by varying the etching voltages and time, and the formation mechanism of interfacial microporous structure has been discussed in detail as well. Appropriate interfacial microporous structure is beneficial for separating the thick GaN crystal grown by HVPE from sapphire during the cooling down process. The separation that occurred at the place of interfacial microporous can be attributed to the large thermal strain between GaN and sapphire. This work realized the fabrication of a free-standing GaN substrate with high crystal quality and nearly no residual strain.

  19. Imine-linked polymer-derived nitrogen-doped microporous carbons with excellent CO2 capture properties.

    PubMed

    Wang, Jiacheng; Senkovska, Irena; Oschatz, Martin; Lohe, Martin R; Borchardt, Lars; Heerwig, Andreas; Liu, Qian; Kaskel, Stefan

    2013-04-24

    A series of nitrogen-doped microporous carbons (NCs) was successfully prepared by direct pyrolysis of high-surface-area microporous imine-linked polymer (ILP, 744 m(2)/g) which was formed using commercial starting materials based on the Schiff base condensation under catalyst-free conditions. These NCs have moderate specific surface areas of up to 366 m(2)/g, pore volumes of 0.43 cm(3)/g, narrow micropore size distributions, and a high density of nitrogen functional groups (5.58-8.74%). The resulting NCs are highly suitable for CO2 capture adsorbents because of their microporous textural properties and large amount of Lewis basic sites. At 1 bar, NC-800 prepared by the pyrolysis of ILP at 800 °C showed the highest CO2 uptakes of 1.95 and 2.65 mmol/g at 25 and 0 °C, respectively. The calculated adsorption capacity for CO2 per m(2) (μmol of CO2/m(2)) of NC-800 is 7.41 μmol of CO2/m(2) at 1 bar and 25 °C, the highest ever reported for porous carbon adsorbents. The isosteric heats of CO2 adsorption (Qst) for these NCs are as high as 49 kJ/mol at low CO2 surface coverage, and still ~25 kJ/mol even at high CO2 uptake (2.0 mmol/g), respectively. Furthermore, these NCs also exhibit high stability, excellent adsorption selectivity for CO2 over N2, and easy regeneration and reuse without any evident loss of CO2 adsorption capacity.

  20. Suppressed N2O formation during NH3 selective catalytic reduction using vanadium on zeolitic microporous TiO2

    PubMed Central

    Lee, Seung Gwan; Lee, Hyun Jeong; Song, Inhak; Youn, Seunghee; Kim, Do Heui; Cho, Sung June

    2015-01-01

    Emission of N2O from mobile and off-road engine is now being currently regulated because of its high impact compared to that of CO2, thereby implying that N2O formation from the exhaust gas after-treatment system should be suppressed. Selective catalytic reduction using vanadium supported TiO2 catalyst in mobile and off-road engine has been considered to be major source for N2O emission in the system. Here we have demonstrated that vanadium catalyst supported on zeolitic microporous TiO2 obtained from the hydrothermal reaction of bulk TiO2 at 400 K in the presence of LiOH suppresses significantly the N2O emission compared to conventional VOx/TiO2 catalyst, while maintaining the excellent NOx reduction, which was ascribed to the location of VOx domain in the micropore of TiO2, resulting in the strong metal support interaction. The use of zeolitic microporous TiO2 provides a new way of preparing SCR catalyst with a high thermal stability and superior catalytic performance. It can be also extended further to the other catalytic system employing TiO2-based substrate. PMID:26235671

  1. Introduction of an ionic liquid into the micropores of a metal-organic framework and its anomalous phase behavior.

    PubMed

    Fujie, Kazuyuki; Yamada, Teppei; Ikeda, Ryuichi; Kitagawa, Hiroshi

    2014-10-13

    Controlling the dynamics of ionic liquids (ILs) is a significant issue for widespread use. Metal-organic frameworks (MOFs) are ideal host materials for ILs because of their small micropores and tunable host-guest interactions. Herein, we demonstrate the first example of an IL incorporated within the micropores of a MOF. The system studied consisted of EMI-TFSA (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide) and ZIF-8 (composed of Zn(MeIM)2 ; H(MeIM)=2-methylimidazole) as the IL and MOF, respectively. Construction of the EMI-TFSA in ZIF-8 was confirmed by X-ray powder diffraction, nitrogen gas adsorption, and infrared absorption spectroscopy. Differential scanning calorimetry and solid-state NMR measurements showed that the EMI-TFSA inside the micropores demonstrated no freezing transition down to 123 K, whereas bulk EMI-TFSA froze at 231 K. Such anomalous phase behavior originates from the nanosize effect of the MOF on the IL. This result provides a novel strategy for stabilizing the liquid phase of the ILs down to a lower temperature region. PMID:25167856

  2. Degradation of N-nitrosodimethylamine (NDMA) and its precursor dimethylamine (DMA) in mineral micropores induced by microwave irradiation.

    PubMed

    He, Yuanzhen; Cheng, Hefa

    2016-05-01

    Removal of N-nitrosodimethylamine (NDMA) in drinking water treatment poses a significant technical challenge due to its small molecular size, high polarity and water solubility, and poor biodegradability. Degradation of NDMA and its precursor, dimethylamine (DMA), was investigated by adsorbing them from aqueous solution using porous mineral sorbents, followed by destruction under microwave irradiation. Among the mineral sorbents evaluated, dealuminated ZSM-5 exhibited the highest sorption capacities for NDMA and DMA, which decreased with the density of surface cations present in the micropores. In contrast, the degradation rate of the sorbed NDMA increased with the density of surface cations under microwave irradiation. Evolutions of the degradation products and C/N ratio indicate that the sorbed NDMA and DMA could be eventually mineralized under continuous microwave irradiation. The degradation rate was strongly correlated with the bulk temperature of ZSM-5 and microwave power, which is consistent with the mechanism of pyrolysis caused by formation of micro-scale "hot spots" within the mineral micropores under microwave irradiation. Compared to existing treatment options for NDMA removal, microporous mineral sorption coupled with microwave-induced degradation has the unique advantages of being able to simultaneously remove NDMA and DMA and cause their full mineralization, and thus could serve as a promising alternative method. PMID:26971806

  3. Biodiesel production from sunflower, soybean, and waste cooking oils by transesterification using lipase immobilized onto a novel microporous polymer.

    PubMed

    Dizge, Nadir; Aydiner, Coskun; Imer, Derya Y; Bayramoglu, Mahmut; Tanriseven, Aziz; Keskinler, Bülent

    2009-03-01

    This study aims at carrying out lipase-catalyzed synthesis of fatty acid methyl esters (biodiesel) from various vegetable oils using lipase immobilized onto a novel microporous polymeric matrix (MPPM) as a low-cost biocatalyst. The research is focused on three aspects of the process: (a) MPPM synthesis (monolithic, bead, and powder forms), (b) microporous polymeric biocatalyst (MPPB) preparation by immobilization of lipase onto MPPM, and (c) biodiesel production by MPPB. Experimental planning of each step of the study was separately carried out in accordance with design of experiment (DoE) based on Taguchi methodology. Microporous polymeric matrix (MPPM) containing aldehyde functional group was synthesized by polyHIPE technique using styrene, divinylbenzene, and polyglutaraldehyde. Thermomyces lanuginosus lipase was covalently attached onto MPPM with 80%, 85%, and 89% immobilization efficiencies using bead, powder, and monolithic forms, respectively. Immobilized enzymes were successfully used for the production of biodiesel using sunflower, soybean, and waste cooking oils. It was shown that immobilized enzymes retain their activities during 10 repeated batch reactions at 25 degrees C, each lasting 24h. Since the developed novel method is simple yet effective, it could have a potential to be used industrially for the production of chemicals requiring immobilized lipases. PMID:19028094

  4. Suppressed N2O formation during NH3 selective catalytic reduction using vanadium on zeolitic microporous TiO2.

    PubMed

    Lee, Seung Gwan; Lee, Hyun Jeong; Song, Inhak; Youn, Seunghee; Kim, Do Heui; Cho, Sung June

    2015-08-03

    Emission of N2O from mobile and off-road engine is now being currently regulated because of its high impact compared to that of CO2, thereby implying that N2O formation from the exhaust gas after-treatment system should be suppressed. Selective catalytic reduction using vanadium supported TiO2 catalyst in mobile and off-road engine has been considered to be major source for N2O emission in the system. Here we have demonstrated that vanadium catalyst supported on zeolitic microporous TiO2 obtained from the hydrothermal reaction of bulk TiO2 at 400 K in the presence of LiOH suppresses significantly the N2O emission compared to conventional VOx/TiO2 catalyst, while maintaining the excellent NOx reduction, which was ascribed to the location of VOx domain in the micropore of TiO2, resulting in the strong metal support interaction. The use of zeolitic microporous TiO2 provides a new way of preparing SCR catalyst with a high thermal stability and superior catalytic performance. It can be also extended further to the other catalytic system employing TiO2-based substrate.

  5. Highly microporous carbons derived from a complex of glutamic acid and zinc chloride for use in supercapacitors

    NASA Astrophysics Data System (ADS)

    Dong, Xiao-Ling; Lu, An-Hui; He, Bin; Li, Wen-Cui

    2016-09-01

    The selection of carbon precursor is an important factor when designing carbon materials. In this study, a complex derived from L-glutamic acid and zinc chloride was used to prepare highly microporous carbons via facile pyrolysis. L-glutamic acid, a new carbon precursor with nitrogen functionality, coordinated with zinc chloride resulted in a homogeneous distribution of Zn2+ on the molecular level. During pyrolysis, the evaporation of the in situ formed zinc species creates an abundance of micropores together with the inert gases. The obtained carbons exhibit high specific surface area (SBET: 1203 m2 g-1) and a rich nitrogen content (4.52 wt%). In excess of 89% of the pore volume consists of micropores with pore size ranging from 0.5 to 1.2 nm. These carbons have been shown to be suitable for use as supercapacitor electrodes, and have been tested in 6 M KOH where a capacitance of 217 F g-1 was achieved at a current density of 0.5 A g-1. A long cycling life of 30 000 cycles was achieved at a current density of 1 A g-1, with only a 9% loss in capacity. The leakage current through a two-electrode device was measured as 2.3 μA per mg of electrode and the self-discharge characteristics were minimal.

  6. Suppressed N2O formation during NH3 selective catalytic reduction using vanadium on zeolitic microporous TiO2

    NASA Astrophysics Data System (ADS)

    Lee, Seung Gwan; Lee, Hyun Jeong; Song, Inhak; Youn, Seunghee; Kim, Do Heui; Cho, Sung June

    2015-08-01

    Emission of N2O from mobile and off-road engine is now being currently regulated because of its high impact compared to that of CO2, thereby implying that N2O formation from the exhaust gas after-treatment system should be suppressed. Selective catalytic reduction using vanadium supported TiO2 catalyst in mobile and off-road engine has been considered to be major source for N2O emission in the system. Here we have demonstrated that vanadium catalyst supported on zeolitic microporous TiO2 obtained from the hydrothermal reaction of bulk TiO2 at 400 K in the presence of LiOH suppresses significantly the N2O emission compared to conventional VOx/TiO2 catalyst, while maintaining the excellent NOx reduction, which was ascribed to the location of VOx domain in the micropore of TiO2, resulting in the strong metal support interaction. The use of zeolitic microporous TiO2 provides a new way of preparing SCR catalyst with a high thermal stability and superior catalytic performance. It can be also extended further to the other catalytic system employing TiO2-based substrate.

  7. Hollow Fiber Spacesuit Water Membrane Evaporator Development and Testing for Advanced Spacesuits

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Trevino, Luis A.; Tsioulos, Gus; Settles, Joseph; Colunga, Aaron; Vogel, Matthew; Vonau, Walt

    2010-01-01

    The spacesuit water membrane evaporator (SWME) is being developed to perform the thermal control function for advanced spacesuits to take advantage of recent advances in micropore membrane technology in providing a robust heat-rejection device that is potentially less sensitive to contamination than is the sublimator. Principles of a sheet membrane SWME design were demonstrated using a prototypic test article that was tested in a vacuum chamber at JSC in July 1999. The Membrana Celgard X50-215 microporous hollow fiber (HoFi) membrane was selected after recent contamination tests as the most suitable candidate among commercial alternatives for HoFi SWME prototype development. A design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype consisting 14,300 tube bundled into 30 stacks, each of which are formed into a chevron shape and separated by spacers and organized into three sectors of ten nested stacks. Vacuum chamber testing has been performed characterize heat rejection as a function of inlet water temperature and water vapor backpressure and to show contamination resistance to the constituents expected to be found in potable water produced by the distillation processes. Other tests showed the tolerance to freezing and suitability to reject heat in a Mars pressure environment.

  8. The influence of variations in biophysical conditions on hemolysis near ultrasonically activated gas-filled micropores

    SciTech Connect

    Miller, D.L.; Thomas, R.M. )

    1990-05-01

    Hemolysis induced by 1.9-MHz ultrasound in 0.5% suspensions of canine erythrocytes with 3.7-{mu}m-diam micropore-trapped gas bodies was investigated for a variety of biophysical conditions. For isotonic media, hemolysis increased with exposure duration but did not greatly change with exposure temperature, or prior heat treatment. The temperature results were especially interesting because increased temperatures might have been expected to increase the sensitivity of the cells to the ultrasonically activated gas bodies. Variations in osmolarity had little influence on the results. Increasing the viscosity of the medium decreased the effect, and this did not seem to depend on the molecular weight of the dextran additive. A medium with elevated mass density seemed to increase the effectiveness of the exposures. This condition eliminated the density difference between the cells and the medium, and might have been expected to reduce the effectiveness of the exposures, because the radiation force, which theoretically gathers cells to the gas bodies, is minimized for such conditions. This information should aid in developing refinements to the theoretical understanding of low-intensity ultrasonic bioeffects.

  9. Direct Observation of Xe and Kr Adsorption in a Xe-selective Microporous Metal Organic Framework

    DOE PAGES

    Chen, Xianyin; Plonka, Anna M.; Banerjee, Debasis; Krishna, Rajamani; Schaef, Herbert T.; Ghose, Sanjit; Thallapally, Praveen K.; Parise, John B.

    2015-05-22

    We found that the cryogenic separation of noble gases is energy-intensive and expensive, especially when low concentrations are involved. Metal–organic frameworks (MOFs) containing polarizing groups within their pore spaces are predicted to be efficient Xe/Kr solid-state adsorbents, but no experimental insights into the nature of the Xe–network interaction are available to date. Here we report a new microporous MOF (designated SBMOF-2) that is selective toward Xe over Kr under ambient conditions, with a Xe/Kr selectivity of about 10 and a Xe capacity of 27.07 wt % at 298 K. Single-crystal diffraction results show that the Xe selectivity may be attributedmore » to the specific geometry of the pores, forming cages built with phenyl rings and enriched with polar -OH groups, both of which serve as strong adsorption sites for polarizable Xe gas. The Xe/Kr separation in SBMOF-2 was investigated with experimental and computational breakthrough methods. These experiments showed that Kr broke through the column first, followed by Xe, which confirmed that SBMOF-2 has a real practical potential for separating Xe from Kr. Our calculations showed that the capacity and adsorption selectivity of SBMOF-2 are comparable to those of the best-performing unmodified MOFs such as NiMOF-74 or Co formate.« less

  10. Preparing two-dimensional microporous carbon from Pistachio nutshell with high areal capacitance as supercapacitor materials

    NASA Astrophysics Data System (ADS)

    Xu, Jiandong; Gao, Qiuming; Zhang, Yunlu; Tan, Yanli; Tian, Weiqian; Zhu, Lihua; Jiang, Lei

    2014-07-01

    Two-dimensional (2D) porous carbon AC-SPN-3 possessing of amazing high micropore volume ratio of 83% and large surface area of about 1069 m2 g-1 is high-yield obtained by pyrolysis of natural waste Pistachio nutshells with KOH activation. The AC-SPN-3 has a curved 2D lamellar morphology with the thickness of each slice about 200 nm. The porous carbon is consists of highly interconnected uniform pores with the median pore diameter of about 0.76 nm, which could potentially improve the performance by maximizing the electrode surface area accessible to the typical electrolyte ions (such as TEA+, diameter = ~0.68 nm). Electrochemical analyses show that AC-SPN-3 has significantly large areal capacitance of 29.3/20.1 μF cm-2 and high energy density of 10/39 Wh kg-1 at power of 52/286 kW kg-1 in 6 M KOH aqueous electrolyte and 1 M TEABF4 in EC-DEC (1:1) organic electrolyte system, respectively.

  11. Preparing two-dimensional microporous carbon from Pistachio nutshell with high areal capacitance as supercapacitor materials.

    PubMed

    Xu, Jiandong; Gao, Qiuming; Zhang, Yunlu; Tan, Yanli; Tian, Weiqian; Zhu, Lihua; Jiang, Lei

    2014-07-02

    Two-dimensional (2D) porous carbon AC-SPN-3 possessing of amazing high micropore volume ratio of 83% and large surface area of about 1069 m(2) g(-1) is high-yield obtained by pyrolysis of natural waste Pistachio nutshells with KOH activation. The AC-SPN-3 has a curved 2D lamellar morphology with the thickness of each slice about 200 nm. The porous carbon is consists of highly interconnected uniform pores with the median pore diameter of about 0.76 nm, which could potentially improve the performance by maximizing the electrode surface area accessible to the typical electrolyte ions (such as TEA(+), diameter = ~0.68 nm). Electrochemical analyses show that AC-SPN-3 has significantly large areal capacitance of 29.3/20.1 μF cm(-2) and high energy density of 10/39 Wh kg(-1) at power of 52/286 kW kg(-1) in 6 M KOH aqueous electrolyte and 1 M TEABF4 in EC-DEC (1:1) organic electrolyte system, respectively.

  12. The contribution of sulfate ions and protons to the specific capacitance of microporous carbon monoliths

    NASA Astrophysics Data System (ADS)

    Barranco, V.; Garcia-Gomez, A.; Kunowsky, M.; Linares-Solano, A.; Ibañez, J.; King, M.; Rojo, J. M.

    2014-09-01

    The monoliths studied in this work show large specific surface areas (up to 1600 m2 g-1), high densities (up to 1.17 g cm-3) and high electrical conductivities (up to 9.5 S cm-1). They are microporous carbons with pore sizes up to 1.3 nm but most of them below 0.75 nm. They also show oxygen functionalities. The electrochemical behavior of the monoliths is studied in three-electrode cells with aqueous H2SO4 solution as electrolyte. This work deals with the contribution of the sulfate ions and protons to the specific capacitance of carbon monoliths having different surface areas and different contents of oxygen groups. Protons contribute with a pseudocapacitance (up to 152 F g-1) in addition to the double layer capacitance. Sulfate ions contribute with a double layer capacitance only. At the double layer, the capacitance of the sulfate ions (up to 291 F g-1) is slightly higher than that of protons (up to 251 F g-1); both capacitances increase as the surface area increases. The preference of protons to be electroadsorbed at the double layer and the broader voltage window of these ions account for their higher contribution (70%) to the double layer capacitance.

  13. Direct Observation of Xe and Kr Adsorption in a Xe-selective Microporous Metal Organic Framework

    SciTech Connect

    Chen, Xianyin; Plonka, Anna M.; Banerjee, Debasis; Krishna, Rajamani; Schaef, Herbert T.; Ghose, Sanjit; Thallapally, Praveen K.; Parise, John B.

    2015-05-22

    We found that the cryogenic separation of noble gases is energy-intensive and expensive, especially when low concentrations are involved. Metal–organic frameworks (MOFs) containing polarizing groups within their pore spaces are predicted to be efficient Xe/Kr solid-state adsorbents, but no experimental insights into the nature of the Xe–network interaction are available to date. Here we report a new microporous MOF (designated SBMOF-2) that is selective toward Xe over Kr under ambient conditions, with a Xe/Kr selectivity of about 10 and a Xe capacity of 27.07 wt % at 298 K. Single-crystal diffraction results show that the Xe selectivity may be attributed to the specific geometry of the pores, forming cages built with phenyl rings and enriched with polar -OH groups, both of which serve as strong adsorption sites for polarizable Xe gas. The Xe/Kr separation in SBMOF-2 was investigated with experimental and computational breakthrough methods. These experiments showed that Kr broke through the column first, followed by Xe, which confirmed that SBMOF-2 has a real practical potential for separating Xe from Kr. Our calculations showed that the capacity and adsorption selectivity of SBMOF-2 are comparable to those of the best-performing unmodified MOFs such as NiMOF-74 or Co formate.

  14. Fabrication and characterization of micro-porous cellulose filters for indoor air quality control.

    PubMed

    Yoon, Younghan; Kim, Sungyoun; Ahn, Kwang Ho; Ko, Kwang Baik; Kim, Kwang-Soo

    2016-01-01

    Micro-porous cellulose filters were fabricated from paper mulberry pulp, which has been used for thousands of years with Korean history. 'Han-ji' is the name of a traditional paper used widely in Korea in construction, textile, craftworks and many household items but before now it has not been used for filtration purpose. Seeking for the utilization of this abundant natural material, this study aims to develop a fabrication process for the traditional paper to be used as a filter for dust filtration, and evaluate the performance by lab-scale experiments. To create pores in the paper, cellulose pulp was pretreated using several methods such as TEMPO oxidation and enzyme hydrolysis, or freeze dried with an alcoholic freezing medium, t-butyl alcohol, instead of water. The filters were characterized and their dust removal performance was tested at a lab scale while also monitoring pressure loss. Chemical oxidation and enzymatic pretreatment were helpful in fabricating a homogeneous filter but would not remove fine-dust particles because of its loose, enlarged pores. The best removal efficiency was observed with filters that were not pretreated but in which water had been exchanged with t-butyl alcohol before freeze-drying. The filter attained a dust removal efficiency higher than 99% over the entire experimental period, with a pressure loss of less than 230 Pa, at a 6.67 (cm3/s)/cm2 air-to-cloth ratio.

  15. An electrochemical and high-speed imaging study of micropore decontamination by acoustic bubble entrapment.

    PubMed

    Offin, Douglas G; Birkin, Peter R; Leighton, Timothy G

    2014-03-14

    Electrochemical and high-speed imaging techniques are used to study the abilities of ultrasonically-activated bubbles to clean out micropores. Cylindrical pores with dimensions (diameter × depth) of 500 μm × 400 μm (aspect ratio 0.8), 125 μm × 350 μm (aspect ratio 2.8) and 50 μm × 200 μm (aspect ratio 4.0) are fabricated in glass substrates. Each pore is contaminated by filling it with an electrochemically inactive blocking organic material (thickened methyl salicylate) before the substrate is placed in a solution containing an electroactive species (Fe(CN)6(3-)). An electrode is fabricated at the base of each pore and the Faradaic current is used to monitor the decontamination as a function of time. For the largest pore, decontamination driven by ultrasound (generated by a horn type transducer) and bulk fluid flow are compared. It is shown that ultrasound is much more effective than flow alone, and that bulk fluid flow at the rates used cannot decontaminate the pore completely, but that ultrasound can. In the case of the 125 μm pore, high-speed imaging is used to elucidate the cleaning mechanisms involved in ultrasonic decontamination and reveals that acoustic bubble entrapment is a key feature. The smallest pore is used to explore the limits of decontamination and it is found that ultrasound is still effective at this size under the conditions employed.

  16. Reactive Melt Infiltration of Silicon-Niobium Alloys in Microporous Carbons

    NASA Technical Reports Server (NTRS)

    Singh, M.; Behrendt, D. R.

    1994-01-01

    Studies of the reactive melt infiltration of silicon-niobium alloys in microporous carbon preforms prepared by the pyrolysis of a polymer precursor have been carried out using modeling, Differential Thermal Analysis (DTA), and melt infiltration. Mercury porosimetry results indicate a very narrow pore size distribution with virtually all the porosity within the carbon preforms open to infiltrants. The morphology and amount of the residual phases (niobium disilicide and silicon) in the infiltrated material can be tailored according to requirements by careful control of the properties (pore size and pore volume) of the porous carbon preforms and alloy composition. The average room temperature four-point flexural strength of a reaction-formed silicon carbide material (made by the infiltration of medium pore size carbon preform with Si - 5 at. % Nb alloy) is 290 +/- 40 MPa (42 +/- 6 ksi) and the fracture toughness is 3.7 +/- 0.3 MPa square root of m. The flexural strength decreases at high temperatures due to relaxation of residual thermal stresses and the presence of free silicon in the material.

  17. Activated Microporous Carbon Derived from Almond Shells for High Energy Density Asymmetric Supercapacitors.

    PubMed

    Wu, Chun; Yang, Shaoran; Cai, Junjie; Zhang, Qiaobao; Zhu, Ying; Zhang, Kaili

    2016-06-22

    Via the activation treatment of carbonized almond shells with HNO3 and KOH, activated microporous carbon (AMC-3 and AMC-2) was successfully synthesized. These two AMC electrodes demonstrate remarkable electrochemical behaviors such as high rate capability, high specific capacitance, and excellent cycle stability when serving as electrodes for supercapacitors. More importantly, through the use of a Zn-Ni-Co ternary oxide (ZNCO) positive electrode and the AMC negative electrode, asymmetric supercapacitors (ASC) were assembled that deliver superior energy density (53.3 Wh kg(-1) at a power density of 1126.1 W kg(-1) for ASC-2 and 53.6 Wh kg(-1) at a power density of 1124.5 W kg(-1) for ASC-3) and excellent stability (82.7% and 83.4% specific capacitance retention for ZNCO//AMC ASC-2 and ZNCO//AMC ASC-3, respectively, after 5000 cycles). Through these two methods, low-cost, renewable, and environmentally friendly electrode materials can be provided for high energy density supercapacitors. PMID:27253880

  18. Modelling metal centres, acid sites and reaction mechanisms in microporous catalysts.

    PubMed

    O'Malley, Alexander J; Logsdail, A J; Sokol, A A; Catlow, C R A

    2016-07-01

    We discuss the role of QM/MM (embedded cluster) computational techniques in catalytic science, in particular their application to microporous catalysis. We describe the methodologies employed and illustrate their utility by briefly summarising work on metal centres in zeolites. We then report a detailed investigation into the behaviour of methanol at acidic sites in zeolites H-ZSM-5 and H-Y in the context of the methanol-to-hydrocarbons/olefins process. Studying key initial steps of the reaction (the adsorption and subsequent methoxylation), we probe the effect of framework topology and Brønsted acid site location on the energetics of these initial processes. We find that although methoxylation is endothermic with respect to the adsorbed system (by 17-56 kJ mol(-1) depending on the location), there are intriguing correlations between the adsorption/reaction energies and the geometries of the adsorbed species, of particular significance being the coordination of methyl hydrogens. These observations emphasise the importance of adsorbate coordination with the framework in zeolite catalysed conversions, and how this may vary with framework topology and site location, particularly suited to investigation by QM/MM techniques. PMID:27136967

  19. Preparation and characterization of microporous fibers for sample preparation and LC-MS determination of drugs.

    PubMed

    Buszewski, Boguslaw; Nowaczyk, Jacek; Ligor, Tomasz; Olszowy, Pawel; Ligor, Magdalena; Wasiniak, Bartlomiej; Miekisch, Wolfram; Schubert, Jochen K; Amann, Anton

    2009-07-01

    The aim of this study was the preparation of polypyrrole (PPy) fibers for solid phase microextraction (SPME). PPy coatings were obtained during the electrochemical polymerization process. The utility of various metal wires (Fe, Cu, Ag, Cu/Ag, kanthal and medical stainless steel) as a support for polymers was compared. Various experimental conditions of the synthesis process such as scan rate, voltage limits and number of scans and deposition time were applied. The average polymer thickness was in the range of 7-125 microm and its weight was in the scope of 0.65-5.6 mg. Different techniques, mainly elemental analysis, Fourier transform infrared spectroscopy, microscopy, and chromatography were performed for the characterization of obtained fibers with microporous structure. The extraction efficiency of cardiovascular drugs (metoprolol, propranolol, oxprenolol, propafenone and mexiletine) by means of fibers was tested. The concentration of mentioned compounds in standard solution was in the span of 10-150 ng/mL. LC-MS was employed for determination of drugs in desorption solution. LODs varied from 0.013 to 1.51 ng/mL for metoprolol and mexiletine respectively. The repeatability of extraction was obtained with the RSD values lower than 10%. PMID:19569094

  20. The hydrogen-storing microporous silica 'Microcluster' reduces acetaldehyde contained in a distilled spirit.

    PubMed

    Kato, Shinya; Miwa, Nobuhiko

    2016-12-01

    Acetaldehyde is a detrimental substance produced in alcoholic liquor aging. We assessed an ability of hydrogen-storing microporous silica 'Microcluster' (MC+) to reduce acetaldehyde, as compared with autoclave-dehydrogenated MC+ (MC-). Acetaldehyde was quantified spectrophotometrically by an enzymatic method. Authentic acetaldehyde was treated by MC+ for 20min, and decreased from 43.4ppm to 10.9ppm, but maintained at 49.3ppm by MC-. On the other hand, acetaldehyde contained in a distilled spirit was decreased from 29.5ppm to 3.1ppm at 20min by MC+, but not decreased by MC-. Addition of MC+ or MC- to distilled water without acetaldehyde showed no seeming effect on the quantification used. Accordingly acetaldehyde in a distilled spirit is reduced to ethanol by hydrogen contained in MC+, but not by the silica moiety of MC+. Hydrogen gas of 1.2mL was released for 20min from MC+ of 0.59g in water, resulting in dissolved hydrogen of 1.09ppm and an oxidation- reduction potential of -687.0mV indicative of a marked reducing ability. Thus, MC+ has an ability to reduce acetaldehyde in a distilled spirit due to dissolved hydrogen released from MC+. PMID:27612695