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Sample records for composite metal membranes

  1. Composite metal membrane

    DOEpatents

    Peachey, N.M.; Dye, R.C.; Snow, R.C.; Birdsell, S.A.

    1998-04-14

    A composite metal membrane including a first metal layer of Group IVB met or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof is provided together with a process for the recovery of hydrogen from a gaseous mixture including contacting a hydrogen-containing gaseous mixture with a first side of a nonporous composite metal membrane including a first metal of Group IVB metals or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof, and, separating hydrogen from a second side of the nonporous composite metal membrane.

  2. Composite metal membrane

    DOEpatents

    Peachey, Nathaniel M.; Dye, Robert C.; Snow, Ronny C.; Birdsell, Stephan A.

    1998-01-01

    A composite metal membrane including a first metal layer of Group IVB met or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof is provided together with a process for the recovery of hydrogen from a gaseous mixture including contacting a hydrogen-containing gaseous mixture with a first side of a nonporous composite metal membrane including a first metal of Group IVB metals or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof, and, separating hydrogen from a second side of the nonporous composite metal membrane.

  3. Novel preparation techniques for thin metal-ceramic composite membranes

    SciTech Connect

    Yeung, K.L.; Varma, A.

    1995-09-01

    Composite metal membranes obtained by supporting thin metallic films on ceramic substrates have good thermal and mechanical stability. The use of a thin metal film increases transmembrane flux, while retaining high permselectivity that is characteristic of metallic membranes. Novel techniques have been developed for preparing metal-ceramic composite membranes. By the appropriate use of osmotic pressure, the microstructure, porosity, and thickness of the deposited metal can be systematically manipulated. Three new procedures are described for film densification and fabrication: (1) the osmotic pressure is used to densify an existing supported metal membrane; (2) densification and growth of the film is managed under the influence of osmotic pressure by using a dilute plating solution; and (3) films of varying porosity are deposited on the ceramic membrane by combining electroless deposition and osmotic pressure. Silver, palladium, and palladium-silver films prepared by these techniques on a commercial alumina membrane (Membralox) are thermally more stable than similar films deposited by conventional electroless plating.

  4. Hydrogen-permeable composite metal membrane and uses thereof

    DOEpatents

    Edlund, David J.; Friesen, Dwayne T.

    1993-06-08

    Various hydrogen production and hydrogen sulfide decomposition processes are disclosed that utilize composite metal membranes that contain an intermetallic diffusion barrier separating a hydrogen-permeable base metal and a hydrogen-permeable coating metal. The barrier is a thermally stable inorganic proton conductor.

  5. Method of making sulfur-resistant composite metal membranes

    DOEpatents

    Way, J Douglas [Boulder, CO; Lusk, Mark [Golden, CO; Thoen, Paul [Littleton, CO

    2012-01-24

    The invention provides thin, hydrogen-permeable, sulfur-resistant membranes formed from palladium or palladium-alloy coatings on porous, ceramic or metal supports. Also disclosed are methods of making these membranes via sequential electroless plating techniques, wherein the method of making the membrane includes decomposing any organic ligands present on the substrate, reducing the palladium crystallites on the substrate to reduced palladium crystallites, depositing a film of palladium metal on the substrate and then depositing a second, gold film on the palladium film. These two metal films are then annealed at a temperature between about 200.degree. C. and about 1200.degree. C. to form a sulfur-resistant, composite PdAu alloy membrane.

  6. Composite Membranes for CO2 Capture: High Performance Metal Organic Frameworks/Polymer Composite Membranes for Carbon Dioxide Capture

    SciTech Connect

    2010-07-01

    IMPACCT Project: A team of six faculty members at Georgia Tech are developing an enhanced membrane by fitting metal organic frameworks, compounds that show great promise for improved carbon capture, into hollow fiber membranes. This new material would be highly efficient at removing CO2 from the flue gas produced at coal-fired power plants. The team is analyzing thousands of metal organic frameworks to identify those that are most suitable for carbon capture based both on their ability to allow coal exhaust to pass easily through them and their ability to select CO2 from that exhaust for capture and storage. The most suitable frameworks would be inserted into the walls of the hollow fiber membranes, making the technology readily scalable due to their high surface area. This composite membrane would be highly stable, withstanding the harsh gas environment found in coal exhaust.

  7. Method for preparation of thermally and mechanically stable metal/porous substrate composite membranes

    DOEpatents

    Damle, Ashok S.

    2004-07-13

    A method is provided for the preparation of metal/porous substrate composite membranes by flowing a solution of metal to be plated over a first surface of a porous substrate and concurrently applying a pressure of gas on a second surface of the porous substrate, such that the porous substrate separates the solution of metal from the gas, and the use of the resulting membrane for the production of highly purified hydrogen gas.

  8. Metalized Nanocellulose Composites as a Feasible Material for Membrane Supports: Design and Applications for Water Treatment.

    PubMed

    Cruz-Tato, Perla; Ortiz-Quiles, Edwin O; Vega-Figueroa, Karlene; Santiago-Martoral, Liz; Flynn, Michael; Díaz-Vázquez, Liz M; Nicolau, Eduardo

    2017-04-04

    Herein, we study the feasibility of using nanocellulose (NC)-based composites with silver and platinum nanoparticles as additive materials to fabricate the support layer of thin film composite (TFC) membranes for water purification applications. In brief, the NC surface was chemically modified and then was decorated with silver and platinum nanoparticles, respectively, by chemical reduction. These metalized nanocellulose composites (MNC) were characterized by several techniques including: FTIR, XPS, TGA, XRD, and XANES to probe their integrity. Thereafter, we fabricated the MNC-TFC membranes and the support layer was modified to improve the membrane properties. The membranes were thoroughly characterized, and the performance was evaluated in forward osmosis (FO) mode with various feed solutions: nanopure water, urea, and wastewater samples. The fabricated membranes exhibited finger-like pore morphologies and varying pore sizes. Interestingly, higher water fluxes and solute rejection was obtained with the MNC-TFC membranes with wastewater samples. The overall approach of this work provides an effort to fabricated membranes with high water flux and enhanced selectivity.

  9. Electrospun cellulose acetate composites containing supported metal nanoparticles for antifungal membranes.

    PubMed

    Quirós, Jennifer; Gonzalo, Soledad; Jalvo, Blanca; Boltes, Karina; Perdigón-Melón, José Antonio; Rosal, Roberto

    2016-09-01

    Electrospun cellulose acetate composites containing silver and copper nanoparticles supported in sepiolite and mesoporous silica were prepared and tested as fungistatic membranes against the fungus Aspergillus niger. The nanoparticles were in the 3-50nm range for sepiolite supported materials and limited by the size of mesopores (5-8nm) in the case of mesoporous silica. Sepiolite and silica were well dispersed within the fibers, with larger aggregates in the micrometer range, and allowed a controlled release of metals to create a fungistatic environment. The effect was assessed using digital image analysis to evaluate fungal growth rate and fluorescence readings using a viability stain. The results showed that silver and copper nanomaterials significantly impaired the growth of fungi when the spores were incubated either in direct contact with particles or included in cellulose acetate composite membranes. The fungistatic effect took place on germinating spores before hyphae growth conidiophore formation. After 24h the cultures were separated from fungistatic materials and showed growth impairment only due to the prior exposure. Growth reduction was important for all the particles and membranes with respect to non-exposed controls. The effect of copper and silver loaded materials was not significantly different from each other with average reductions around 70% for bare particles and 50% for membranes. Copper on sepiolite was particularly efficient with a decrease of metabolic activity of up to 80% with respect to controls. Copper materials induced rapid maturation and conidiation with fungi splitting in sets of subcolonies. Metal-loaded nanomaterials acted as reservoirs for the controlled release of metals. The amount of silver or copper released daily by composite membranes represented roughly 1% of their total load of metals. Supported nanomaterials encapsulated in nanofibers allow formulating active membranes with high antifungal performance at the same time

  10. Thermally tolerant multilayer metal membrane

    DOEpatents

    Dye, Robert C.; Snow, Ronny C.

    2001-01-01

    A composite metal membrane including a first metal layer of a Group IVB or Group VB metal sandwiched between two layers of a Group VIIIB metal selected from the group consisting of palladium, platinum, nickel, rhodium, iridium, cobalt, and alloys thereof, and a non-continuous layer of a metal chalcogenide upon one layer of the Group VIIIB metal is disclosed together with a process for the recovery of hydrogen from a gaseous mixture using such a composite membrane and a process for forming such a composite metal membrane.

  11. Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for heavy metal removal.

    PubMed

    Genç, O; Soysal, L; Bayramoğlu, G; Arica, M Y; Bektaş, S

    2003-02-28

    The effective removal of toxic heavy metals from environmental samples still remains a major topic of present research. Metal-chelating membranes are very promising materials as adsorbents when compared with conventional beads because they are not compressible, and they eliminate internal diffusion limitations. The purpose of this study was to evaluate the performance of a novel adsorbent, Procion Green H-4G immobilized poly(hydroxyethylmethacrylate (HEMA)/chitosan) composite membranes, for the removal of three toxic heavy metal ions, namely, Cd(II), Pb(II) and Hg(II) from aquatic systems. The Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes were characterized by elemental analysis, scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The immobilized amount of the Procion Green H-4G was calculated as 0.018+/-0.003 micromol/cm(2) from the nitrogen and sulphur stoichiometry. The adsorption capacity of Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for selected heavy metal ions from aqueous media containing different amounts of these ions (30-400mg/l) and at different pH values (2.0-6.0) was investigated. The amount of Cd(II), Pb(II) and Hg(II) adsorbed onto the membranes measured at equilibrium, increased with time during the first 45 min and then remained unchanged toward the equilibrium adsorption. The maximum amounts of heavy metal ions adsorbed were 43.60+/-1.74, 68.81+/-2.75 and 48.22+/-1.92 mg/g for Cd(II), Pb(II) and Hg(II), respectively. The heavy metal ion adsorption on the pHEMA/chitosan membranes (carrying no dye) were relatively low, 6.31+/-0.13 mg/g for Cd(II), 18.73+/-0.37 mg/g for Pb(II) and 18.82+/-0.38 mg/g for Hg(II). Competitive adsorption of the metal ions was also studied. When the metal ions competed with each other, the adsorbed amounts were 12.74+/-0.38 mg Cd(II)/g, 28.80+/-0.86 mg Pb(II)/g and 18.41+/-0.54 mg Hg(II)/g. Procion

  12. Solid Oxide Membrane (SOM) Process for Facile Electrosynthesis of Metal Carbides and Composites

    NASA Astrophysics Data System (ADS)

    Zou, Xingli; Chen, Chaoyi; Lu, Xionggang; Li, Shangshu; Xu, Qian; Zhou, Zhongfu; Ding, Weizhong

    2017-02-01

    Metal carbides (MCs) and composites including TiC, SiC, TaC, ZrC, NbC, Ti5Si3/TiC, and Nb/Nb5Si3 have been directly electrosynthesized from their stoichiometric metal oxides/carbon (MOs/C) mixture precursors by an innovative solid oxide membrane (SOM)-assisted electrochemical process. MOs/C mixture powders including TiO2/C, SiO2/C, Ta2O5/C, ZrO2/C, Nb2O5/C, TiO2/SiO2/C, Nb2O5/SiO2 were pressed to form porous pellets and then served as cathode precursors. A SOM-based anode, made from yttria-stabilized zirconia (YSZ)-based membrane, was used to control the electroreduction process. The SOM electrochemical process was performed at 1273 K (1000 °C) and 3.5 to 4.0 V in molten CaCl2. The oxygen component contained in the MOs/C precursors was gradually removed during electroreduction process, and thus, MOs/C can be directly converted into MCs and composites at the cathode. The reaction mechanism of the electroreduction process and the characteristics of the obtained MCs and composites products were systematically investigated. The results show that the electrosynthesis process typically involves compounding, electroreduction, dissolution-electrodeposition, and in situ carbonization processes. The products can be predesigned and controlled to form micro/nanostructured MCs and composites. Multicomponent multilayer composites (MMCs) have also been tried to electrosynthesize in this work. It is suggested that the SOM-assisted electroreduction process has great potential to be used for the facile and green synthesis of various MCs and composites.

  13. Multilayer sulfur-resistant composite metal membranes and methods of making and repairing the same

    SciTech Connect

    Way, J. Douglas; Hatlevik, Oyvind

    2014-07-15

    The invention relates to thin, hydrogen-permeable, sulfur-resistant membranes formed from multi-layers of palladium or palladium-alloy coatings on porous, ceramic or metal supports, methods of making these membranes, methods of repairing layers of these membranes and devices that incorporate these membranes.

  14. Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

    DOEpatents

    Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan; Velikokhatnyi, Oleg

    2017-02-07

    The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VII of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.

  15. Large deformation ionic polymer-metal composites actuators based on porous Nafion membranes

    NASA Astrophysics Data System (ADS)

    Zhao, Dongxu; Li, Dichen; Wang, Yanjie; Luo, Meng; Chen, Hualing

    2016-04-01

    With advantages of low driving voltage, good flexibility and high electromechanical efficiency, ionic polymer-metal composites (IPMCs), which are one of the most attractive smart materials, have been research hotspot in actuators, sensors and artificial muscles. However, a serious drawback of little deformation of thick IPMC actuator limits its application. In this paper, we fabricated thick porous Nafion membranes by freeze-drying process. A series of Thermogravimetric analyses (TGA), Field emission scanning electron microscopy (FE-SEM) and Water uptake (WUP) tests were performed to examine the validity of the freeze-drying process and the pore size and the porosity. Then, the porous IPMCs were fabricated with the freeze-drying processed Nafion membranes by the solution casting and reducing plating. Finally, the IPMC actuators with the dimensions of 25× 5× 1 in millimeters were achieved and tested. The terminal deformation of the porous IPMC actuator increased by 739.7%, compared with the ordinary IPMC actuator with the same dimensions under the driving voltage of 2VDC.

  16. Composite fuel cell membranes

    DOEpatents

    Plowman, K.R.; Rehg, T.J.; Davis, L.W.; Carl, W.P.; Cisar, A.J.; Eastland, C.S.

    1997-08-05

    A bilayer or trilayer composite ion exchange membrane is described suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

  17. Composite fuel cell membranes

    DOEpatents

    Plowman, Keith R.; Rehg, Timothy J.; Davis, Larry W.; Carl, William P.; Cisar, Alan J.; Eastland, Charles S.

    1997-01-01

    A bilayer or trilayer composite ion exchange membrane suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

  18. Interactive Thermal Effects on Metal-Organic Framework Polymer Composite Membranes.

    PubMed

    Cacho-Bailo, Fernando; Téllez, Carlos; Coronas, Joaquín

    2016-07-04

    Polymeric membranes are important tools for intensifying separation processes in chemical industries, concerning strategic tasks such as CO2 sequestration, H2 production, and water supply and disposal. Mixed-matrix and supported membranes have been widely developed; recently many of them have been based on metal-organic frameworks (MOFs). However, most of the impacts MOFs have within the polymer matrix have yet to be determined. The effects related to thermal behavior arising from the combination of MOF ZIF-8 and polysulfone have now been quantified. The catalyzed oxidation of the polymer is strongly affected by the MOF crystal size and distribution inside the membrane. A 16 wt % 140 nm-sized ZIF-8 loading causes a 40 % decrease in the observed activation energy of the polysulfone oxidation that takes place at a temperature (545 °C) 80 °C lower than in the raw polymer (625 °C).

  19. Composite zeolite membranes

    DOEpatents

    Nenoff, Tina M.; Thoma, Steven G.; Ashley, Carol S.; Reed, Scott T.

    2002-01-01

    A new class of composite zeolite membranes and synthesis techniques therefor has been invented. These membranes are essentially defect-free, and exhibit large levels of transmembrane flux and of chemical and isotopic selectivity.

  20. Surface Decoration of Amino-Functionalized Metal-Organic Framework/Graphene Oxide Composite onto Polydopamine-Coated Membrane Substrate for Highly Efficient Heavy Metal Removal.

    PubMed

    Rao, Zhuang; Feng, Kai; Tang, Beibei; Wu, Peiyi

    2017-01-25

    A new metal-organic framework/graphene oxide composite (IRMOF-3/GO) with high adsorption capacity of copper(II) (maximal adsorption amount = 254.14 mg/g at pH 5.0 and 25 °C) was prepared. Novel and highly efficient nanofiltration (NF) membrane can be facilely fabricated via surface decoration of IRMOF-3/GO onto polydopamine (PDA)-coated polysulfone (PSF) substrate. After decoration of IRMOF-3/GO, membrane surface potential increased from 6.7 to 13.1 mV at pH 5.0 and 25 °C. Due to the adsorption effect of IRMOF-3/GO and the enhancement of membrane surface potential, the prepared NF membrane (the loading amount of IRMOF-3/GO is ca. 13.6 g/m(2)) exhibits a highly efficient rejection of copper(II). The copper(II) rejection reaches up to ∼90%, while maintaining a relatively high flux of ∼31 L/m(2)/h at the pressure of 0.7 MPa and pH 5.0. Moreover, the membrane also presents an outstanding stability throughout the 2000 min NF testing period. Thus, the newly developed NF membrane shows a promising potential for water cleaning. This work provides a worthy reference for designing highly efficient NF membranes modified by metal-organic framework (MOF) relevant materials.

  1. Solid polymer electrolyte composite membrane comprising a porous support and a solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide

    DOEpatents

    Liu, Han; Mittelsteadt, Cortney K; Norman, Timothy J; Griffith, Arthur E; LaConti, Anthony B

    2015-02-24

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a thin, rigid, dimensionally-stable, non-electrically-conducting support, the support having a plurality of cylindrical, straight-through pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores are unevenly distributed, with some or no pores located along the periphery and more pores located centrally. The pores are completely filled with a solid polymer electrolyte, the solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide. The solid polymer electrolyte may also be deposited over the top and/or bottom surfaces of the support.

  2. A Metal Chelating Porous Polymeric Support: The Missing Link for a Defect-Free Metal-Organic Framework Composite Membrane.

    PubMed

    Barankova, Eva; Tan, Xiaoyu; Villalobos, Luis Francisco; Litwiller, Eric; Peinemann, Klaus-Viktor

    2017-03-06

    Since the discovery of size-selective metal-organic frameworks (MOFs), researchers have tried to incorporate these materials into gas separation membranes. Impressive gas selectivities were found, but these MOF membranes were mostly made on inorganic supports, which are generally too bulky and expensive for industrial gas separation. Forming MOF layers on porous polymer supports is industrially attractive but technically challenging. Two features to overcome these problems are described: 1) a metal chelating support polymer to bind the MOF layer, and 2) control of MOF crystal growth by contra-diffusion, aiming at a very thin nanocrystalline MOF layer. Using a metal chelating poly-thiosemicarbazide (PTSC) support and adjusting the metal and organic ligand concentrations carefully, a very compact ZIF-8 (ZIF=zeolitic imidazolate framework) layer was produced that displayed interference colors because of its smooth surface and extreme thinness-within the range of visible light. High performances were measured in terms of hydrogen/propane (8350) and propylene/propane (150) selectivity.

  3. Polyarylether composition and membrane

    DOEpatents

    Hung, Joyce; Brunelle, Daniel Joseph; Harmon, Marianne Elisabeth; Moore, David Roger; Stone, Joshua James; Zhou, Hongyi; Suriano, Joseph Anthony

    2010-11-09

    A composition including a polyarylether copolymer is provided. The copolymer includes a polyarylether backbone; and a sulfonated oligomeric group bonded to the polyarylether suitable for use as a cation conducting membrane. Method of bonding a sulfonated oligomeric group to the polyarylether backbone to form a polyarylether copolymer. The membrane may be formed from the polyarylether copolymer composition. The chain length of the sulfonated oligomeric group may be controlled to affect or control the ion conductivity of the membrane.

  4. Ionic polymer-metal composite actuators employing sulfonated poly (styrene-ethylene-butylene-styrene) as ionic-exchange membranes

    NASA Astrophysics Data System (ADS)

    Wang, Xuan-Lun; Oh, Il-Kwon; Lu, Jun; Ju, Jin-Hun; Lee, Sun-Woo

    2007-07-01

    There is growing interest in biomimetic motions by employing ionic polymer-metal composites (IPMCs) as the candidates for the fabrication of artificial muscle. However, the membrane materials currently used in IPMC actuators have been limited to a few commercially available perfluorinated ionic polymers, such as Nafion, and they suffer from several shortcomings among which their high cost presents a major obstacle for wide application. With excellent proton conductivity and high water uptake capacity, commercially available Sulfonated poly (styrene-ethylene-butylene-styrene) (SEBS) of low cost has been investigated for many years as a fuel cell membrane. Herein, we report the preparation of a novel IPMC actuator based on the sulfonated SEBS (SSEBS) membrane. The platinum electrodes of the SEBS actuators were obtained with electroless plating procedure, and the cation exchange with lithium was performed by soaking the composite membranes into a 1.5N LiCl solution. The surface and cross-sectional morphologies of the SSEBS actuators were observed by using scanning electron microscopy (SEM), which revealed that the platinum layer up to 8µm was deposited on the top and bottom surfaces of the SSEBS membrane. The electromechanical bending responses were investigated under alternating current excitations with various driving frequencies and voltage amplitudes, which showed high electrical strains under sinusoidal signal. The effect of the membrane thickness on the performance of the actuators was also addressed in this presentation. This kind of IPMC has great potentials for the applications in biomimetic sensors and actuators, which can be utilized to mimic the locomotion of fish and insects and can be applied to micro-robots and bio-medical devices as well.

  5. Ionic polymer-metal composite actuators obtained from radiation-grafted cation- and anion-exchange membranes.

    PubMed

    Park, Jong Hyuk; Han, Man Jae; Song, Dae Seock; Jho, Jae Young

    2014-12-24

    Two series of ionic polymer-metal composites (IPMCs), one cationic and one anionic, are designed and prepared from radiation-grafted ion-exchange membranes. Through examination of the properties of the membranes synthesized from the two grafting monomers and the two base polymers, acrylic acid-grafted poly(vinylidene fluoride-co-hexafluoropropylene) and quarternized 4-vinylpyridine-grafted poly(ethylene-co-tetrafluoroethylene) with the appropriate amount of ionic groups are employed for the fabrication of cation and anion IPMCs, respectively. The bending displacement of the cation IPMC is comparable to Nafion-based IPMC under direct- and alternating-current voltage, but back-relaxation is not observed. The actuation performance of the anion IPMC is highly improved over those reported earlier in the literature for the other anion IPMCs.

  6. The Influence of Pores in Track Etched Membranes and Prepared on their Base Polymer/Metal Composites on their Fracture Strength

    NASA Astrophysics Data System (ADS)

    Gumirova, V. N.; Bedin, S. A.; Abdurashidova, G. S.; Razumovskaya, I. V.

    The strength of track etched membranes and prepared on their base polymer/metal composites is analysed in point of view of the pores form evolution during the extension and the interaction of elastic mechanical fields on closely positioned pores. The stress-strain curves for track membranes and composites PET/Cu are demonstrated for pore density 1.2×107сm-2 and diameters from 0.06 μm to 2.9 μm

  7. A review of composite and metallic bipolar plates in proton exchange membrane fuel cell: Materials, fabrication, and material selection

    NASA Astrophysics Data System (ADS)

    Taherian, Reza

    2014-11-01

    Proton exchange membrane (PEM) fuel cells offer exceptional potential for a clean, efficient, and reliable power source. The bipolar plate (BP) is a key component in this device, as it connects each cell electrically, supplies reactant gases to both anode and cathode, and removes reaction products from the cell. BPs have primarily been fabricated from high-density graphite, but in recent years, much attention has been paid to develop the cost-effective and feasible alternative materials. Recently, two different classes of materials have been attracted attention: metals and composite materials. This paper offers a comprehensive review of the current researches being carried out on the metallic and composite BPs, covering materials and fabrication methods. In this research, the phenomenon of ionic contamination due to the release of the corrosion products of metallic BP and relative impact on the durability as well as performance of PEM fuel cells is extensively investigated. Furthermore, in this paper, upon several effective parameters on commercialization of PEM fuel cells, such as stack cost, weight, volume, durability, strength, ohmic resistance, and ionic contamination, a material selection is performed among the most common BPs currently being used. This material selection is conducted by using Simple Additive Weighting Method (SAWM).

  8. Crown-Ether Derived Graphene Hybrid Composite for Membrane-Free Potentiometric Sensing of Alkali Metal Ions.

    PubMed

    Olsen, Gunnar; Ulstrup, Jens; Chi, Qijin

    2016-01-13

    We report the design and synthesis of newly functionalized graphene hybrid material that can be used for selective membrane-free potentiometric detection of alkali metal ions, represented by potassium ions. Reduced graphene oxide (RGO) functionalized covalently by 18-crown[6] ether with a dense surface coverage is achieved by the introduction of a flexible linking molecule. The resulting hybrid composite is highly stable and is capable of detecting potassium ions down to micromolar ranges with a selectivity over other cations (including Ca(2+), Li(+), Na(+), NH4(+)) at concentrations up to 25 mM. This material can be combined further with disposable chips, demonstrating its promise as an effective ion-selective sensing component for practical applications.

  9. METAL COMPOSITIONS

    DOEpatents

    Seybolt, A.U.

    1959-02-01

    Alloys of uranium which are strong, hard, and machinable are presented, These alloys of uranium contain bctween 0.1 to 5.0% by weight of at least one noble metal such as rhodium, palladium, and gold. The alloys may be heat treated to obtain a product with iniproved tensile and compression strengths,

  10. Ionic Polymer-Metal Composites (IPMCs) with Various Ion Exchange Membranes and Their Potential Use in IPMC Applications

    NASA Astrophysics Data System (ADS)

    Park, Jiyeon

    Ionic polymer metal composites (IPMCs) have been widely studied and drawn great attention for the last several years in robotics and medical fields due to their great potential as actuators, artificial muscles, and more. Each part of an IPMC is important, but the role of ionic exchange membrane should be emphasized because, after all, it is where ions migrate when voltage is applied to produce motion. So far, most researches have been done on IPMCs made with commercially available ionic exchange membranes such as Nafion or Flemion. In this thesis, the research is mainly focused on fabricating IPMCs with several other ionic exchange membranes that are commercially available and characterization of optical, physical, and electromechanical properties of those IPMCs. Five different ion exchange membranes of DuPont (N115), Golden Energy Fuel Cells Inc (GEFC-700)., fuMA Tech (F-14100), Membranes International Inc. (CMI-7000S) and University of Nevada Las Vegas (19-PSU-S1) are the chosen membranes. N115, GEFC-700, and F-14100 have the same structure. CMI-7000S is a reinforced membrane by mixing fibers with the ion exchange membrane. 19-PSU-S1 is a membrane that was made at UNLV for fuel cell application. The physical properties of the ionic exchange membranes were studied by examining water uptake. The thermal analysis also was carried out with Differential Scanning Calorimetry (DSC). Water uptake and ion exchange capacities were measured to confirm the physical properties of IPMCs. The structure of the IPMCs was observed under Scanning Electron Microscopy (SEM). The structures of fabricated IPMCs were observed by SEM and DSC. Capacitance was also measured by drawing impedance curves. Young's modulus (E) was measured to determine the stiffness of each IPMC. Lastly, bending actuation test was carried out to observe the actual performance of each IPMC in water. The water uptake of all IPMCs is less than 40%. 19-PSU-S1 absorbed the most water (35.2 %) and CMI-7000S absorbed

  11. Amorphous metal composites

    DOEpatents

    Byrne, Martin A.; Lupinski, John H.

    1984-01-01

    An improved amorphous metal composite and process of making the composite. The amorphous metal composite comprises amorphous metal (e.g. iron) and a low molecular weight thermosetting polymer binder. The process comprises placing an amorphous metal in particulate form and a thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  12. 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.

  13. 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.

  14. 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.

  15. Composite oxygen transport membrane

    DOEpatents

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2016-11-15

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  16. Composite oxygen transport membrane

    DOEpatents

    Christie, Gervase Maxwell; Lane, Jonathan A.

    2014-08-05

    A method of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. In the porous fuel oxidation layer and the optional porous surface exchange layer, A is Calcium and in the dense separation layer A is not Calcium and, preferably is Strontium. Preferred materials are (La.sub.0.8Ca.sub.0.2).sub.0.95Cr.sub.0.5Mn.sub.0.5O.sub.3-.delta. for the porous fuel oxidation and optional porous surface exchange layers and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer. The use of such materials allows the membrane to sintered in air and without the use of pore formers to reduce membrane manufacturing costs. The use of materials, as described herein, for forming the porous layers have application for forming any type of porous structure, such as a catalyst support.

  17. Metal etching composition

    NASA Technical Reports Server (NTRS)

    Otousa, Joseph E. (Inventor); Thomas, Clark S. (Inventor); Foster, Robert E. (Inventor)

    1991-01-01

    The present invention is directed to a chemical etching composition for etching metals or metallic alloys. The composition includes a solution of hydrochloric acid, phosphoric acid, ethylene glycol, and an oxidizing agent. The etching composition is particularly useful for etching metal surfaces in preparation for subsequent fluorescent penetrant inspection.

  18. Complexation-induced phase separation: preparation of composite membranes with a nanometer-thin dense skin loaded with metal ions.

    PubMed

    Villalobos, Luis Francisco; Karunakaran, Madhavan; Peinemann, Klaus-Viktor

    2015-05-13

    We present the development of a facile phase-inversion method for forming asymmetric membranes with a precise high metal ion loading capacity in only the dense layer. The approach combines the use of macromolecule-metal intermolecular complexes to form the dense layer of asymmetric membranes with nonsolvent-induced phase separation to form the porous support. This allows the independent optimization of both the dense layer and porous support while maintaining the simplicity of a phase-inversion process. Moreover, it facilitates control over (i) the thickness of the dense layer throughout several orders of magnitude from less than 15 nm to more than 6 μm, (ii) the type and amount of metal ions loaded in the dense layer, (iii) the morphology of the membrane surface, and (iv) the porosity and structure of the support. This simple and scalable process provides a new platform for building multifunctional membranes with a high loading of well-dispersed metal ions in the dense layer.

  19. Proton Conductance of a Superior Water-Stable Metal-Organic Framework and Its Composite Membrane with Poly(vinylidene fluoride).

    PubMed

    Luo, Hong-Bin; Wang, Mei; Liu, Shao-Xian; Xue, Chen; Tian, Zheng-Fang; Zou, Yang; Ren, Xiao-Ming

    2017-03-22

    Proton-exchange membranes (PEMs) as separators have important technological applications in electrochemical devices, including fuel cells, electrochemical sensors, electrochemical reactors, and electrochromic displays. The composite membrane of a proton-conducting metal-organic framework (MOF) and an organic polymer combines the unique physical and chemical nature of the polymer and the high proton conductivity of the MOF, bringing together the best of both components to potentially fabricate high-performance PEMs. In this study, we have investigated the proton-transport nature of a zirconium(IV) MOF, MOF-808 (1). This superior-water-stability MOF shows striking proton conductivity with σ = 7.58 × 10(-3) S·cm(-1) at 315 K and 99% relative humidity. The composite membranes of 1 and poly(vinylidene fluoride) (PVDF) have further been fabricated and are labeled as 1@PVDF-X, where X represents the mass percentage of 1 (as X%) in 1@PVDF-X and X = 10-55%. The composite membranes exhibit good mechanical features and durability for practical application and a considerable proton conductivity of 1.56 × 10(-4) S·cm(-1) in deionized water at 338 K as well. Thus, the composite membranes show promising applications as alternative PEMs in diverse electrochemical devices.

  20. Composite oxygen transport membrane

    SciTech Connect

    Lu, Zigui; Plonczak, Pawel J.; Lane, Jonathan A.

    2016-11-08

    A method is described of producing a composite oxygen ion membrane and a composite oxygen ion membrane in which a porous fuel oxidation layer and a dense separation layer and optionally, a porous surface exchange layer are formed on a porous support from mixtures of (Ln.sub.1-xA.sub.x).sub.wCr.sub.1-yB.sub.yO.sub.3-.delta. and a doped zirconia. Preferred materials are (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.7Fe.sub.0.3O.sub.3-.delta. for the porous fuel oxidation layer, (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.5Fe.sub.0.5O.sub.3-.delta. for the dense separation layer, and (La.sub.0.8Sr.sub.0.2).sub.0.95Cr.sub.0.3Fe.sub.0.7O.sub.3-.delta. for the porous surface exchange layer. Firing the said fuel activation and separation layers in nitrogen atmosphere unexpectedly allows the separation layer to sinter into a fully densified mass.

  1. Composite membrane with integral rim

    DOEpatents

    Routkevitch, Dmitri; Polyakov, Oleg G

    2015-01-27

    Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

  2. Stable catalyst layers for hydrogen permeable composite membranes

    SciTech Connect

    Way, J. Douglas; Wolden, Colin A

    2014-01-07

    The present invention provides a hydrogen separation membrane based on nanoporous, composite metal carbide or metal sulfide coated membranes capable of high flux and permselectivity for hydrogen without platinum group metals. The present invention is capable of being operated over a broad temperature range, including at elevated temperatures, while maintaining hydrogen selectivity.

  3. Composite sensor membrane

    DOEpatents

    Majumdar, Arun; Satyanarayana, Srinath; Yue, Min

    2008-03-18

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

  4. Supported Molten Metal Membranes for Hydrogen Separation

    SciTech Connect

    Datta, Ravindra; Ma, Yi Hua; Yen, Pei-Shan; Deveau, Nicholas; Fishtik, Ilie; Mardilovich, Ivan

    2013-09-30

    We describe here our results on the feasibility of a novel dense metal membrane for hydrogen separation: Supported Molten Metal Membrane, or SMMM.1 The goal in this work was to develop these new membranes based on supporting thin films of low-melting, non- precious group metals, e.g., tin (Sn), indium (In), gallium (Ga), or their alloys, to provide a flux and selectivity of hydrogen that rivals the conventional but substantially more expensive palladium (Pd) or Pd alloy membranes, which are susceptible to poisoning by the many species in the coal-derived syngas, and further possess inadequate stability and limited operating temperature range. The novelty of the technology presented numerous challenges during the course of this project, however, mainly in the selection of appropriate supports, and in the fabrication of a stable membrane. While the wetting instability of the SMMM remains an issue, we did develop an adequate understanding of the interaction between molten metal films with porous supports that we were able to find appropriate supports. Thus, our preliminary results indicate that the Ga/SiC SMMM at 550 ºC has a permeance that is an order of magnitude higher than that of Pd, and exceeds the 2015 DOE target. To make practical SMM membranes, however, further improving the stability of the molten metal membrane is the next goal. For this, it is important to better understand the change in molten metal surface tension and contact angle as a function of temperature and gas-phase composition. A thermodynamic theory was, thus, developed, that is not only able to explain this change in the liquid-gas surface tension, but also the change in the solid-liquid surface tension as well as the contact angle. This fundamental understanding has allowed us to determine design characteristics to maintain stability in the face of changing gas composition. These designs are being developed. For further progress, it is also important to understand the nature of solution and

  5. Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Mortensen, Andreas; Llorca, Javier

    2010-08-01

    In metal matrix composites, a metal is combined with another, often nonmetallic, phase to produce a novel material having attractive engineering attributes of its own. A subject of much research in the 1980s and 1990s, this class of materials has, in the past decade, increased significantly in variety. Copper matrix composites, layered composites, high-conductivity composites, nanoscale composites, microcellular metals, and bio-derived composites have been added to a palette that, ten years ago, mostly comprised ceramic fiber- or particle-reinforced light metals together with some well-established engineering materials, such as WC-Co cermets. At the same time, research on composites such as particle-reinforced aluminum, aided by novel techniques such as large-cell 3-D finite element simulation or computed X-ray microtomography, has served as a potent vehicle for the elucidation of the mechanics of high-contrast two-phase elastoplastic materials, with implications that range well beyond metal matrix composites.

  6. Layered plasma polymer composite membranes

    DOEpatents

    Babcock, W.C.

    1994-10-11

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is [>=]2 and is the number of selective layers. 2 figs.

  7. Composite solid polymer electrolyte membranes

    DOEpatents

    Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.

    2001-06-19

    The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

  8. Composite solid polymer electrolyte membranes

    DOEpatents

    Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.

    2006-05-30

    The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

  9. Hard metal composition

    DOEpatents

    Sheinberg, H.

    1983-07-26

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 wt % boron carbide and the remainder a metal mixture comprising from 70 to 90% tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 and 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  10. Hard metal composition

    DOEpatents

    Sheinberg, Haskell

    1986-01-01

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  11. Composite membrane, method of preparation and use

    SciTech Connect

    Blume, I.; Pinnau, I.

    1990-10-16

    This paper discusses a membrane for gas separation or pervaporation. The membrane is a composite of a microporous support membrane and an ultrathin permselective membrane, the permselective membrane being made from a polyamide-polyether block copolymer. The membrane is particularly useful in separating polar gases from non-polar gases.

  12. Hydrocarbon-based polymer electrolyte cerium composite membranes for improved proton exchange membrane fuel cell durability

    NASA Astrophysics Data System (ADS)

    Lee, Hyejin; Han, Myungseong; Choi, Young-Woo; Bae, Byungchan

    2015-11-01

    Hydrocarbon-based cerium composite membranes were prepared for proton exchange membrane fuel cell applications to increase oxidative stability. Different amounts of cerium ions were impregnated in sulfonated poly(arylene ether sulfone) (SPES) membranes and their physicochemical properties were investigated according to the cerium content. Field-emission scanning electron microscopy and inductively coupled plasma analyses confirmed the presence of cerium ions in the composite membranes and 1H NMR indicated the successful coordination of sulfonic acid groups with the metal ions. Increasing amounts of cerium ions resulted in decreases in the proton conductivity and water uptake, but enhanced oxidative stability. The oxidative stability of the composite membranes was proven via a hydrogen peroxide exposure experiment which mimicked fuel cell operating conditions. In addition, more than 2200 h was achieved with the composite membrane under in situ accelerated open circuit voltage (OCV) durability testing (DOE protocol), whereas the corresponding pristine SPES membrane attained only 670 h.

  13. Nanostructured metal-polyaniline composites

    DOEpatents

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2010-08-31

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  14. Composite polymeric/ceramic pervaporation membrane reactor

    SciTech Connect

    Zhu, Y.; Tsotsis, T.T.

    1995-12-01

    We have investigated the preparation of composite polymeric/ceramic membranes. We have studied the effect of the preparation techniques on the properties of these composite membranes. A model has been developed to describe the transport characteristics. We have used these membranes in pervaporation membrane reactor applications. Our experimental data and modeling results will be presented.

  15. Metal Nanoparticle Aerogel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Sibille, Laurent; Ignont, Erica; Snow, Lanee; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have fabricated sol-gels containing gold and silver nanoparticles. Formation of an aerogel produces a blue shift in the surface plasmon resonance as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping this blue shift does not obey effective medium theories. Annealing the samples in a reducing atmosphere at 400 C eliminates this discrepancy and results in narrowing and further blue shifting of the plasmon resonance. Metal particle aggregation also results in a deviation from the predictions of effective medium theories, but can be controlled through careful handling and by avoiding the use of alcohol. By applying effective medium theories to the heterogeneous interlayer surrounding each metal particle, we extend the technique of immersion spectroscopy to inhomogeneous materials characterized by spatially dependent dielectric constants, such as aerogels. We demonstrate that the shift in the surface plasmon wavelength provides the average fractional composition of each component (air and silica) in this inhomogeneous layer, i.e. the porosity of the aerogel or equivalently, for these materials, the catalytic dispersion. Additionally, the kinetics suggest that collective particle interactions in coagulated metal clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  16. Dimensionally stable metallic hydride composition

    DOEpatents

    Heung, Leung K.

    1994-01-01

    A stable, metallic hydride composition and a process for making such a composition. The composition comprises a uniformly blended mixture of a metal hydride, kieselguhr, and a ballast metal, all in the form of particles. The composition is made by subjecting a metal hydride to one or more hydrogen absorption/desorption cycles to disintegrate the hydride particles to less than approximately 100 microns in size. The particles are partly oxidized, then blended with the ballast metal and the kieselguhr to form a uniform mixture. The mixture is compressed into pellets and calcined. Preferably, the mixture includes approximately 10 vol. % or more kieselguhr and approximately 50 vol. % or more ballast. Metal hydrides that can be used in the composition include Zr, Ti, V, Nb, Pd, as well as binary, tertiary, and more complex alloys of La, Al, Cu, Ti, Co, Ni, Fe, Zr, Mg, Ca, Mn, and mixtures and other combinations thereof. Ballast metals include Al, Cu and Ni.

  17. Preparation and characterization of water-soluble carbon nanotube reinforced Nafion membranes and so-based ionic polymer metal composite actuators

    NASA Astrophysics Data System (ADS)

    Ru, Jie; Wang, Yanjie; Chang, Longfei; Chen, Hualing; Li, Dichen

    2016-09-01

    In this paper, we developed a new kind of ionic polymer metal composite (IPMC) actuator by doping water-soluble sulfonated multi-walled carbon nanotube (sMWCNT) into Nafion matrix to overcome some major drawbacks of traditional IPMCs, such as relatively low bending deformation and carring capacity at low driving voltages. Firstly, sMWCNT was synthesized via diazotization coupling reaction, and then doped into Nafion matrix by casting method. Subsequently, the electrochemical and electromechanical properties of sMWCNT-reinforced Nafion membranes and the corresponding IPMCs were investigated. Finally, the effects of sMWCNT on the performances of IPMCs were evaluated and analyzed systematacially. The results showed that sMWCNT was homogeneously dispersed in Nafion matrix without any entangled structure or obvious agglomeration. The main factors for superior actuation performances, like water-uptake ratio, proton conductivity and elastic modulus, increased significantly. Compared to the pure Nafion IPMC and MWCNT/Nafion IPMC, much superior electrochemical and electromechanical performances were achieved in the sMWCNT/Nafion IPMC, which were attributed to the numerous insertion sites, high surface conductivity and excellent mechanical strength as well as the homogeneous dispersity of the incorporated sMWCNT. Herein, a trace amount of sMWCNT can improve the performances of IPMCs significantly for realistic applications.

  18. Electronically Conductive Composite Polymer Membranes.

    DTIC Science & Technology

    1985-09-20

    coats the individual fibers which make up the webs. Clearly, at this loading level ( 10 w/w S Nafion in the Gr), only a small fraction of the...NOO014-82K-0612 Task No. NR 627-838 cc TECHNICAL REPORT NO. 10 Mn Electronically Conductive Composite Polymer Membranes I- I by 0 Reginald M. Penner... 10 of Document Control Data - DO Form 1473. Copies of form available from cognizant contract administrator 85 IV, 03 O88 UNCLASSI FIED SECURITY

  19. Method of making metal-polymer composite catalysts

    DOEpatents

    Zelena, Piotr; Bashyam, Rajesh

    2009-06-23

    A metal-polymer-carbon composite catalyst for use as a cathode electrocatalyst in fuel cells. The catalyst includes a heteroatomic polymer; a transition metal linked to the heteroatomic polymer by one of nitrogen, sulfur, and phosphorus, and a recast ionomer dispersed throughout the heteroatomic polymer-carbon composite. The method includes forming a heteroatomic polymer-carbon composite and loading the transition metal onto the composite. The invention also provides a method of making a membrane electrode assembly for a fuel cell that includes the metal-polymer-carbon composite catalyst.

  20. Composite membranes and methods for making same

    DOEpatents

    Routkevitch, Dmitri; Polyakov, Oleg G

    2012-07-03

    Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

  1. Metal/ceramic composites with high hydrogen permeability

    DOEpatents

    Dorris, Stephen E.; Lee, Tae H.; Balachandran, Uthamalingam

    2003-05-27

    A membrane for separating hydrogen from fluids is provided comprising a sintered homogenous mixture of a ceramic composition and a metal. The metal may be palladium, niobium, tantalum, vanadium, or zirconium or a binary mixture of palladium with another metal such as niobium, silver, tantalum, vanadium, or zirconium.

  2. Reactor process using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.

    1994-01-01

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane. Also disclosed is a method regenerating a porous metal oxide ceramic membrane used in a photoelectrochemical catalytic process by periodically removing the reactants and regenerating the membrane using a variety of chemical, thermal, and electrical techniques.

  3. Reactor process using metal oxide ceramic membranes

    DOEpatents

    Anderson, M.A.

    1994-05-03

    A reaction vessel for use in photoelectrochemical reactions includes as its reactive surface a metal oxide porous ceramic membrane of a catalytic metal such as titanium. The reaction vessel includes a light source and a counter electrode. A provision for applying an electrical bias between the membrane and the counter electrode permits the Fermi levels of potential reaction to be favored so that certain reactions may be favored in the vessel. The electrical biasing is also useful for the cleaning of the catalytic membrane. Also disclosed is a method regenerating a porous metal oxide ceramic membrane used in a photoelectrochemical catalytic process by periodically removing the reactants and regenerating the membrane using a variety of chemical, thermal, and electrical techniques. 2 figures.

  4. Membranes Remove Metal Ions Fron Industrial Liquids

    NASA Technical Reports Server (NTRS)

    Hsu, W. P. L.; May, C.

    1983-01-01

    Use of membrane films affords convenient and economical alternative for removing and recovering metal cations present in low concentrations from large quantities of liquid solutions. Possible applications of membrane films include use in analytical chemistry for determination of small amounts of toxic metallic impurities in lakes, streams, and municipal effluents. Also suitable for use as absorber of certain pollutant gases and odors present in confined areas.

  5. Reactor vessel using metal oxide ceramic membranes

    DOEpatents

    Anderson, Marc A.; Zeltner, Walter A.

    1992-08-11

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

  6. LIQUID METAL COMPOSITIONS CONTAINING URANIUM

    DOEpatents

    Teitel, R.J.

    1959-04-21

    Liquid metal compositions containing a solid uranium compound dispersed therein is described. Uranium combines with tin to form the intermetallic compound USn/sub 3/. It has been found that this compound may be incorporated into a liquid bath containing bismuth and lead-bismuth components, if a relatively small percentage of tin is also included in the bath. The composition has a low thermal neutron cross section which makes it suitable for use in a liquid metal fueled nuclear reactor.

  7. Metallic glass composition

    DOEpatents

    Kroeger, Donald M.; Koch, Carl C.

    1986-01-01

    A metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon carbon and phosphorous to which is added an amount of a ductility enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

  8. Metal ion separations by supported liquid membranes

    SciTech Connect

    Gyves, J. de; San Miguel, E.R. de

    1999-06-01

    Carrier-mediated transport through supported liquid membranes is currently recognized as a potentially valuable technology for selective separation and concentration of toxic and valuable metal ions. In this paper, a review of the fundamental aspects concerning metal ion transport and the influencing factors are surveyed in terms of data modeling, membrane efficiency (permeability, selectivity, stability), and data acquisition and evaluation. An account of the information reviewed demonstrates the need for critical reflection on system performances in order to accomplish scaling up operations. On the same basis, an attempt to outline some future trends in the field is presented.

  9. Novel Metallic Membranes for Hydrogen Separation

    SciTech Connect

    Dogan, Omer

    2011-02-27

    To reduce dependence on oil and emission of greenhouse gases, hydrogen is favored as an energy carrier for the near future. Hydrogen can be converted to electrical energy utilizing fuel cells and turbines. One way to produce hydrogen is to gasify coal which is abundant in the U.S. The coal gasification produces syngas from which hydrogen is then separated. Designing metallic alloys for hydrogen separation membranes which will work in a syngas environment poses significant challenges. In this presentation, a review of technical targets, metallic membrane development activities at NETL and challenges that are facing the development of new technologies will be given.

  10. High Flux Metallic Membranes for Hydrogen Recovery and Membrane Reactors

    SciTech Connect

    Buxbaum, Robert

    2010-06-30

    We made and tested over 250 new alloys for use as lower cost, higher flux hydrogen extraction membrane materials. Most of these were intermetallic, or contained significant intermetallic content, particularly based on B2 alloy compositions with at least one refractory component; B2 intermetallics resemble BCC alloys, in structure, but the atoms have relatively fixed positions, with one atom at the corners of the cube, the other at the centers. The target materals we were looking for would contain little or no expensive elements, no strongly toxic or radioactive elements, would have high flux to hydrogen, while being fabricable, brazable, and relatively immune to hydrogen embrittlement and corrosion in operation. The best combination of properties of the membrane materials we developed was, in my opinion, a Pd-coated membrane consisting of V -9 atomic % Pd. This material was relatively cheap, had 5 times the flux of Pd under the same pressure differential, was reasonably easy to fabricate and braze, and not bad in terms of embrittlement. Based on all these factors we project, about 1/3 the cost of Pd, on an area basis for a membrane designed to last 20 years, or 1/15 the cost on a flux basis. Alternatives to this membrane replaced significant fractions of the Pd with Ni and or Co. The cost for these membranes was lower, but so was the flux. We produced successful brazed products from the membrane materials, and made them into flat sheets. We tested, unsuccessfully, several means of fabricating thematerials into tubes, and eventually built a membrane reactor using a new, flat-plate design: a disc and doughnut arrangement, a design that seems well- suited to clean hydrogen production from coal. The membranes and reactor were tested successfully at Western Research. A larger equipment company (Chart Industries) produced similar results using a different flat-plate reactor design. Cost projections of the membrane are shown to be attractive.

  11. Surface functionalization of metal organic frameworks for mixed matrix membranes

    DOEpatents

    Albenze, Erik; Lartey, Michael; Li, Tao; Luebke, David R.; Nulwala, Hunaid B.; Rosi, Nathaniel L.; Venna, Surendar R.

    2017-03-21

    Mixed Matrix Membrane (MMM) are composite membranes for gas separation and comprising a quantity of inorganic filler particles, in particular metal organic framework (MOF), dispersed throughout a polymer matrix comprising one or more polymers. This disclosure is directed to MOF functionalized through addition of a pendant functional group to the MOF, in order to improve interaction with a surrounding polymer matrix in a MMM. The improved interaction aids in avoiding defects in the MMM due to incompatible interfaces between the polymer matrix and the MOF particle, in turn increasing the mechanical and gas separation properties of the MMM. The disclosure is also directed to a MMM incorporating the surface functionalized MOF.

  12. Synthesis of Carbon Nanotube (CNT) Composite Membranes

    PubMed Central

    Altalhi, Tariq; Ginic-Markovic, Milena; Han, Ninghui; Clarke, Stephen; Losic, Dusan

    2011-01-01

    Carbon nanotubes are attractive approach for designing of new membranes for advanced molecular separation because of their unique transport properties and ability to mimic biological protein channels. In this work the synthetic approach for fabrication of carbon nanotubes (CNTs) composite membranes is presented. The method is based on growth of multi walled carbon nanotubes (MWCNT) using chemical vapour deposition (CVD) on the template of nanoporous alumina (PA) membranes. The influence of experimental conditions including carbon precursor, temperature, deposition time, and PA template on CNT growth process and quality of fabricated membranes was investigated. The synthesis of CNT/PA composites with controllable nanotube dimensions such as diameters (30–150 nm), and thickness (5–100 μm), was demonstrated. The chemical composition and morphological characteristics of fabricated CNT/PA composite membranes were investigated by various characterisation techniques including scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD). Transport properties of prepared membranes were explored by diffusion of dye (Rose Bengal) used as model of hydrophilic transport molecule. PMID:24957494

  13. 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.

  14. 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.

  15. Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs)-Based Composite Membranes: A Review

    PubMed Central

    Ma, Lining; Dong, Xinfa; Chen, Mingliang; Zhu, Li; Wang, Chaoxian; Yang, Fenglin; Dong, Yingchao

    2017-01-01

    Membrane separation technology is widely explored for various applications, such as water desalination and wastewater treatment, which can alleviate the global issue of fresh water scarcity. Specifically, carbon nanotubes (CNTs)-based composite membranes are increasingly of interest due to the combined merits of CNTs and membrane separation, offering enhanced membrane properties. This article first briefly discusses fabrication and growth mechanisms, characterization and functionalization techniques of CNTs, and then reviews the fabrication methods for CNTs-based composite membranes in detail. The applications of CNTs-based composite membranes in water treatment are comprehensively reviewed, including seawater or brine desalination, oil-water separation, removal of heavy metal ions and emerging pollutants as well as membrane separation coupled with assistant techniques. Furthermore, the future direction and perspective for CNTs-based composite membranes are also briefly outlined. PMID:28335452

  16. Islet Amyloid Polypeptide Membrane Interactions: Effects of Membrane Composition.

    PubMed

    Zhang, Xiaoxue; St Clair, Johnna R; London, Erwin; Raleigh, Daniel P

    2017-01-17

    Amyloid formation by islet amyloid polypeptide (IAPP) contributes to β-cell dysfunction in type 2 diabetes. Perturbation of the β-cell membrane may contribute to IAPP-induced toxicity. We examine the effects of lipid composition, salt, and buffer on IAPP amyloid formation and on the ability of IAPP to induce leakage of model membranes. Even low levels of anionic lipids promote amyloid formation and membrane permeabilization. Increasing the percentage of the anionic lipids, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (POPS) or 1,2-dioleoyl-sn-glycero-3-phospho(1'-rac-glycerol), enhances the rate of amyloid formation and increases the level of membrane permeabilization. The choice of zwitterionic lipid has no noticeable effect on membrane-catalyzed amyloid formation but in most cases affects leakage, which tends to decrease in the following order: 1,2-dioleoyl-sn-glycero-3-phosphocholine > 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine > sphingomyelin. Uncharged lipids that increase the level of membrane order weaken the ability of IAPP to induce leakage. Leakage is due predominately to pore formation rather than complete disruption of the vesicles under the conditions used in these studies. Cholesterol at or below physiological levels significantly reduces the rate of vesicle-catalyzed IAPP amyloid formation and decreases the susceptibility to IAPP-induced leakage. The effects of cholesterol on amyloid formation are masked by 25 mol % POPS. Overall, there is a strong inverse correlation between the time to form amyloid and the extent of vesicle leakage. NaCl reduces the rate of membrane-catalyzed amyloid formation by anionic vesicles, but accelerates amyloid formation in solution. The implications for IAPP membrane interactions are discussed, as is the possibility that the loss of phosphatidylserine asymmetry enhances IAPP amyloid formation and membrane damage in vivo via a positive feedback loop.

  17. Advanced metal-membrane technology-commercialization

    SciTech Connect

    Edlund, D.J.

    1995-06-01

    The gasification of coal offers a potentially significant source of hydrogen for use in clean power generation and as a primary chemical feedstock. However, hydrogen derived from coal continues to be more expensive than hydrogen derived from natural gas or petroleum, due in large part to the expense of separating hydrogen from the mixture of gases produced during gasification. At Bend Research, we have been developing a novel hydrogen-permeable metal membrane that promises to be economical for hydrogen separation and purification, including the purification of hydrogen derived from gasifying coal. Furthermore, the membrane is ideally suited for use at high temperatures (200{degrees} to 500{degrees}C), making it feasible to produce pure hydrogen directly from hot gas streams. Through a partnership with Teledyne Wah Chang, we are proceeding with scale-up of prototype membrane modules and field tests to demonstrate the technology to potential users. Additionally, we are working with potential customers to estimate capital savings and operating costs for integrated systems. In this paper, we present some of the operating characteristics of the metal membrane, including its use to drive equilibrium-limited reactions toward complete conversion (e.g., the water-gas-shift reaction). We also describe our activities for commercializing this technology for a variety of applications.

  18. Metal-matrix composites: Status and prospects

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Applications of metal matrix composites for air frames and jet engine components are discussed. The current state of the art in primary and secondary fabrication is presented. The present and projected costs were analyzed to determine the cost effectiveness of metal matrix composites. The various types of metal matrix composites and their characteristics are described.

  19. Composite materials for polymer electrolyte membrane microbial fuel cells.

    PubMed

    Antolini, Ermete

    2015-07-15

    Recently, the feasibility of using composite metal-carbon, metal-polymer, polymer-carbon, polymer-polymer and carbon-carbon materials in microbial fuel cells (MFCs) has been investigated. These materials have been tested as MFC anode catalyst (microorganism) supports, cathode catalysts and membranes. These hybrid materials, possessing the properties of each component, or even with a synergistic effect, would present improved characteristics with respect to the bare components. In this paper we present an overview of the use of these composite materials in microbial fuel cells. The characteristics of the composite materials as well as their effect on MFC performance were compared with those of the individual component and/or the conventionally used materials.

  20. Anion-conducting polymer, composition, and membrane

    DOEpatents

    Pivovar, Bryan S.; Thorn, David L.

    2010-12-07

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  1. Anion-conducting polymer, composition, and membrane

    DOEpatents

    Pivovar, Bryan S.; Thorn, David L.

    2009-09-01

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  2. Anion-conducting polymer, composition, and membrane

    DOEpatents

    Pivovar, Bryan S [Los Alamos, NM; Thorn, David L [Los Alamos, NM

    2011-11-22

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  3. Anion-Conducting Polymer, Composition, and Membrane

    DOEpatents

    Pivovar, Bryan S.; Thorn, David L.

    2008-10-21

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  4. Method of joining metallic and composite components

    NASA Technical Reports Server (NTRS)

    Semmes, Edmund B. (Inventor)

    2010-01-01

    A method is provided for joining a metallic member to a structure made of a composite matrix material. One or more surfaces of a portion of the metallic member that is to be joined to the composite matrix structure is provided with a plurality of outwardly projecting studs. The surface including the studs is brought into engagement with a portion of an uncured composite matrix material so that fibers of the composite matrix material intertwine with the studs, and the metallic member and composite structure form an assembly. The assembly is then companion cured so as to join the metallic member to the composite matrix material structure.

  5. Optimizing Misch-Metal Compositions In Metal Hydride Anodes

    NASA Technical Reports Server (NTRS)

    Bugga, Ratnakumar V.; Halpert, Gerald

    1995-01-01

    Electrochemical cells based on metal hydride anodes investigated experimentally in effort to find anode compositions maximizing charge/discharge-cycle performances. Experimental anodes contained misch metal alloyed with various proportions of Ni, Co, Mn, and Al, and experiments directed toward optimization of composition of misch metal.

  6. Characterization of Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Chun, H. J.; Karalekas, D.

    1994-01-01

    Experimental methods were developed, adapted, and applied to the characterization of a metal matrix composite system, namely, silicon carbide/aluminim (SCS-2/6061 Al), and its constituents. The silicon carbide fiber was characterized by determining its modulus, strength, and coefficient of thermal expansion. The aluminum matrix was characterized thermomechanically up to 399 C (750 F) at two strain rates. The unidirectional SiC/Al composite was characterized mechanically under longitudinal, transverse, and in-plane shear loading up to 399 C (750 F). Isothermal and non-isothermal creep behavior was also measured. The applicability of a proposed set of multifactor thermoviscoplastic nonlinear constitutive relations and a computer code was investigated. Agreement between predictions and experimental results was shown in a few cases. The elastoplastic thermomechanical behavior of the composite was also described by a number of new analytical models developed or adapted for the material system studied. These models include the rule of mixtures, composite cylinder model with various thermoelastoplastic analyses and a model based on average field theory. In most cases satisfactory agreement was demonstrated between analytical predictions and experimental results for the cases of stress-strain behavior and thermal deformation behavior at different temperatures. In addition, some models yielded detailed three-dimensional stress distributions in the constituents within the composite.

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

    DOEpatents

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

    2006-04-04

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

  8. Metal-To-Composite Shaft Splice

    NASA Technical Reports Server (NTRS)

    Kish, Jules; Nguyen, Dean; Lauder, Tim

    1992-01-01

    Strong, lightweight shaft formed without awkward bolted flanges. Composite and metal portions of shaft joined by winding composite portion onto outer surface and into spiral groove of metal portion. Groove and composite material constitute structural bond. If opposing spiral grooves used, then two shafts locked together against torques in both directions.

  9. Donnan dialysis of transition metal ions using anion exchange membrane modified with Xylenol Orange

    SciTech Connect

    Sawicka, B.; Brajter, K.; Trojanowicz, M.; Kado, B. )

    1991-01-01

    A chelating ion-exchange membrane was obtained by modification of a PTFE-based anion-exchange membrane with Xylenol Orange. Its utility for dialysis of Cu(II), Ni(II), Mn(II), and Zn(II) was investigated by using receiver solutions without and with iminodiacetate. 1,2-diaminocyclohexanetetraacetic acid, and tetraethylenepentamine. In comparison to commercial PTFE cation-exchange membranes, modified chelating membranes exhibit for the metal ions investigated a larger differentiation of retention in the membrane phase and transport-to-receiver solution depending on the modifier used and the composition of the receiver solution.

  10. Evaluation of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Okelly, K. P.

    1971-01-01

    The results of an evaluation of candidate metal-matrix composite materials for shuttle space radiators mounted to external structure are presented. The evaluation was specifically applicable to considerations of the manufacturing and properties of a potential space radiator. Two candidates, boron/aluminum and graphite/aluminum were obtained or made in various forms and tested in sufficient depth to allow selection of one of the two for future scale-up programs. The effort accomplished on this program verified that aluminum reinforced with boron was within the state-of-the-art in industry and possessed properties usable in the external skin areas available for shuttle radiators where re-entry temperatures will not exceed 800 F. It further demonstrated that graphite/aluminum has an apparently attractive future for space applications but requires extension development prior to scale-up.

  11. Aqueous alkali metal hydroxide insoluble cellulose ether membrane

    NASA Technical Reports Server (NTRS)

    Hoyt, H. E.; Pfluger, H. L. (Inventor)

    1969-01-01

    A membrane that is insoluble in an aqueous alkali metal hydroxide medium is described. The membrane is a resin which is a water-soluble C2-C4 hydroxyalkyl cellulose ether polymer and an insolubilizing agent for controlled water sorption, a dialytic and electrodialytic membrane. It is particularly useful as a separator between electrodes or plates in an alkaline storage battery.

  12. Chlorine-resistant composite membranes with high organic rejection

    DOEpatents

    McCray, Scott B.; Friesen, Dwayne T.; Barss, Robert P.; Nelson, Leslie D.

    1996-01-01

    A method for making a chlorine-resistant composite polyamide membrane having high organic rejection, the essential step of which comprises treating a conventional composite membrane with an acyl halide. The novel membrane is especially suitable for the treatment of water containing chlorine or lower molecular weight organic compounds.

  13. Metal oxide porous ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1991-01-01

    A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  14. Metal oxide porous ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1992-01-01

    A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  15. Silicon-nitride and metal composite

    DOEpatents

    Landingham, Richard L.; Huffsmith, Sarah A.

    1981-01-01

    A composite and a method for bonding the composite. The composite includes a ceramic portion of silicon nitride, a refractory metal portion and a layer of MoSi.sub.2 indirectly bonding the composite together. The method includes contacting the layer of MoSi.sub.2 with a surface of the silicon nitride and with a surface of the metal; heating the layer to a temperature below 1400.degree. C.; and, simultaneously with the heating, compressing the layer such that the contacting is with a pressure of at least 30 MPa. This composite overcomes useful life problems in the fabrication of parts for a helical expander for use in power generation.

  16. Silicon-nitride and metal composite

    DOEpatents

    Landingham, R.L.; Huffsmith, S.A.

    A composite and a method for bonding the composite are described. The composite includes a ceramic portion of silicon nitride, a refractory metal portion and a layer of MoSi/sub 2/ indirectly bonding the composite together. The method includes contacting the layer of MoSi/sub 2/ with a surface of the silicon nitride and with a surface of the metal; heating the layer to a temperature below 1400/sup 0/C; and, simultaneously, compressing the layer such that the contacting is with a pressure of at least 30 MPa. This composite overcomes useful life problems in the fabrication of parts for a helical expander for use in power generation.

  17. Brazing C-C composites to metals

    SciTech Connect

    Liu, J.Y.; Banerjee, P.; Chin, B.A.

    1994-12-31

    Carbon-carbon composites are attractive for use at high temperature because of their high strength, modulus, chemical stability and resistance to activation by radiation. In these applications, the C-C composite must be joined to itself and to metals. The research described in this paper has led to the invention of a new brazing filler metal from the Cu-Mu-Ti system and the development of a brazing process for joining CC composites to metals. The newly invented brazing filler metal compositions, with controllable melting points ranging from 800{emdash}920{degrees}C has excellent wettability on both C-C composites and metals (stainless steel, Nb, Mo, W, and Zr). Sound joints of C-C composite/metal were produced using the brazing filler metal and the specially developed brazing processes. Finite element analyses were used to predict the residual stress distribution in the brazed joints. Theoretical predictions were confirmed by interlayer experiments. The brazed joints were studied using optical and scanning electron microscopy (SEM) to examine the microstructure and fractured brazed joints. The results showed 100% bonding was obtained using the developed braze metal and brazing procedure.

  18. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1994-01-01

    A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

  19. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1997-01-01

    A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

  20. Composite Membrane with Underwater-Oleophobic Surface for Anti-Oil-Fouling Membrane Distillation.

    PubMed

    Wang, Zhangxin; Hou, Deyin; Lin, Shihong

    2016-04-05

    In this study, we fabricated a composite membrane for membrane distillation (MD) by modifying a commercial hydrophobic polyvinylidene fluoride (PVDF) membrane with a nanocomposite coating comprising silica nanoparticles, chitosan hydrogel and fluoro-polymer. The composite membrane exhibits asymmetric wettability, with the modified surface being in-air hydrophilic and underwater oleophobic, and the unmodified surface remaining hydrophobic. By comparing the performance of the composite membrane and the pristine PVDF membrane in direct contact MD experiments using a saline emulsion with 1000 ppm crude oil (in water), we showed that the fabricated composite membrane was significantly more resistant to oil fouling compared to the pristine hydrophobic PVDF membrane. Force spectroscopy was conducted for the interaction between an oil droplet and the membrane surface using a force tensiometer. The difference between the composite membrane and the pristine PVDF membrane in their interaction with an oil droplet served to explain the difference in the fouling propensities between these two membranes observed in MD experiments. The results from this study suggest that underwater oleophobic coating can effectively mitigate oil fouling in MD operations, and that the fabricated composite membrane with asymmetric wettability can enable MD to desalinate hypersaline wastewater with high concentrations of hydrophobic contaminants.

  1. Anodized Aluminum Oxide Templated Synthesis of Metal-Organic Frameworks Used as Membrane Reactors.

    PubMed

    Yu, Yifu; Wu, Xue-Jun; Zhao, Meiting; Ma, Qinglang; Chen, Junze; Chen, Bo; Sindoro, Melinda; Yang, Jian; Han, Shikui; Lu, Qipeng; Zhang, Hua

    2017-01-09

    The incorporation of metal-organic frameworks (MOFs) into membrane-shaped architectures is of great importance for practical applications. The currently synthesized MOF-based membranes show many disadvantages, such as poor compatibility, low dispersity, and instability, which severely limit their utility. Herein, we present a general, facile, and robust approach for the synthesis of MOF-based composite membranes through the in situ growth of MOF plates in the channels of anodized aluminum oxide (AAO) membranes. After being used as catalysis reactors, they exhibit high catalytic performance and stability in the Knoevenagel condensation reaction. The high catalytic performance might be attributed to the intrinsic structure of MOF-based composite membranes, which can remove the products from the reaction zone quickly, and prevent the aggregation and loss of catalysts during reaction and recycling process.

  2. Urea transport through composite polyallylamine membranes

    NASA Technical Reports Server (NTRS)

    Ballou, E. V.; Kubo, L. Y.; Spitze, L. A.; Wydeven, T.; Clark, J. A.

    1977-01-01

    Polyallylamine composite reverse osmosis membranes were prepared by plasma polymerization and deposition onto small-pored cellulose acetate/cellulose nitrate films. The polyallylamine coated the porous substrate with a thin uniform polymer film which exhibited water permeability and urea rejection, of interest because of the potential application of reverse osmosis to urine purification in closed environmental systems. The flux of C-14 labeled urea was studied under the influence of osmotic gradients provided by sodium chloride solutions. The urea flux was found to be enhanced by an osmotic pressure gradient in the same direction and diminished, but not prevented, by an opposing osmotic pressure gradient. Consideration is given to the mechanism of the urea transport, as well as to the influence of concentration polarization on the experimental results. The minimization of coupled flow in pores of a critical size range is apparently necessary to improve urea rejection.

  3. 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.

  4. Separation of metals by supported liquid membrane

    DOEpatents

    Takigawa, Doreen Y.

    1992-01-01

    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.

  5. Method of making amorphous metal composites

    DOEpatents

    Byrne, Martin A.; Lupinski, John H.

    1982-01-01

    The process comprises placing an amorphous metal in particulate form and a low molecular weight (e.g., 1000-5000) thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  6. Enhanced ethylene separation and plasticization resistance in polymer membranes incorporating metal-organic framework nanocrystals

    NASA Astrophysics Data System (ADS)

    Bachman, Jonathan E.; Smith, Zachary P.; Li, Tao; Xu, Ting; Long, Jeffrey R.

    2016-08-01

    The implementation of membrane-based separations in the petrochemical industry has the potential to reduce energy consumption significantly relative to conventional separation processes. Achieving this goal, however, requires the development of new membrane materials with greater selectivity, permeability and stability than available at present. Here, we report composite materials consisting of nanocrystals of metal-organic frameworks dispersed within a high-performance polyimide, which can exhibit enhanced selectivity for ethylene over ethane, greater ethylene permeability and improved membrane stability. Our results suggest that framework-polymer interactions reduce chain mobility of the polymer while simultaneously boosting membrane separation performance. The increased stability, or plasticization resistance, is expected to improve membrane utility under real process conditions for petrochemical separations and natural gas purification. Furthermore, this approach can be broadly applied to numerous polymers that encounter aggressive environments, potentially making gas separations possible that were previously inaccessible to membranes.

  7. Enhanced ethylene separation and plasticization resistance in polymer membranes incorporating metal-organic framework nanocrystals.

    PubMed

    Bachman, Jonathan E; Smith, Zachary P; Li, Tao; Xu, Ting; Long, Jeffrey R

    2016-08-01

    The implementation of membrane-based separations in the petrochemical industry has the potential to reduce energy consumption significantly relative to conventional separation processes. Achieving this goal, however, requires the development of new membrane materials with greater selectivity, permeability and stability than available at present. Here, we report composite materials consisting of nanocrystals of metal-organic frameworks dispersed within a high-performance polyimide, which can exhibit enhanced selectivity for ethylene over ethane, greater ethylene permeability and improved membrane stability. Our results suggest that framework-polymer interactions reduce chain mobility of the polymer while simultaneously boosting membrane separation performance. The increased stability, or plasticization resistance, is expected to improve membrane utility under real process conditions for petrochemical separations and natural gas purification. Furthermore, this approach can be broadly applied to numerous polymers that encounter aggressive environments, potentially making gas separations possible that were previously inaccessible to membranes.

  8. Fabrication of COF-MOF Composite Membranes and Their Highly Selective Separation of H2/CO2.

    PubMed

    Fu, Jingru; Das, Saikat; Xing, Guolong; Ben, Teng; Valtchev, Valentin; Qiu, Shilun

    2016-06-22

    The search for new types of membrane materials has been of continuous interest in both academia and industry, given their importance in a plethora of applications, particularly for energy-efficient separation technology. In this contribution, we demonstrate for the first time that a metal-organic framework (MOF) can be grown on the covalent-organic framework (COF) membrane to fabricate COF-MOF composite membranes. The resultant COF-MOF composite membranes demonstrate higher separation selectivity of H2/CO2 gas mixtures than the individual COF and MOF membranes. A sound proof for the synergy between two porous materials is the fact that the COF-MOF composite membranes surpass the Robeson upper bound of polymer membranes for mixture separation of a H2/CO2 gas pair and are among the best gas separation MOF membranes reported thus far.

  9. Regulation of the divalent metal ion transporter via membrane budding

    PubMed Central

    Mackenzie, KimberlyD; Foot, Natalie J; Anand, Sushma; Dalton, Hazel E; Chaudhary, Natasha; Collins, Brett M; Mathivanan, Suresh; Kumar, Sharad

    2016-01-01

    The release of extracellular vesicles (EVs) is important for both normal physiology and disease. However, a basic understanding of the targeting of EV cargoes, composition and mechanism of release is lacking. Here we present evidence that the divalent metal ion transporter (DMT1) is unexpectedly regulated through release in EVs. This process involves the Nedd4-2 ubiquitin ligase, and the adaptor proteins Arrdc1 and Arrdc4 via different budding mechanisms. We show that mouse gut explants release endogenous DMT1 in EVs. Although we observed no change in the relative amount of DMT1 released in EVs from gut explants in Arrdc1 or Arrdc4 deficient mice, the extent of EVs released was significantly reduced indicating an adaptor role in biogenesis. Furthermore, using Arrdc1 or Arrdc4 knockout mouse embryonic fibroblasts, we show that both Arrdc1 and Arrdc4 are non-redundant positive regulators of EV release. Our results suggest that DMT1 release from the plasma membrane into EVs may represent a novel mechanism for the maintenance of iron homeostasis, which may also be important for the regulation of other membrane proteins. PMID:27462458

  10. Carbide-reinforced metal matrix composite by direct metal deposition

    NASA Astrophysics Data System (ADS)

    Novichenko, D.; Thivillon, L.; Bertrand, Ph.; Smurov, I.

    Direct metal deposition (DMD) is an automated 3D laser cladding technology with co-axial powder injection for industrial applications. The actual objective is to demonstrate the possibility to produce metal matrix composite objects in a single-step process. Powders of Fe-based alloy (16NCD13) and titanium carbide (TiC) are premixed before cladding. Volume content of the carbide-reinforced phase is varied. Relationships between the main laser cladding parameters and the geometry of the built-up objects (single track, 2D coating) are discussed. On the base of parametric study, a laser cladding process map for the deposition of individual tracks was established. Microstructure and composition of the laser-fabricated metal matrix composite objects are examined. Two different types of structures: (a) with the presence of undissolved and (b) precipitated titanium carbides are observed. Mechanism of formation of diverse precipitated titanium carbides is studied.

  11. Polybenzimidazole-multiwall carbon nanotubes composite membranes for polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Guerrero Moreno, Nayibe; Gervasio, Dominic; Godínez García, Andrés; Pérez Robles, Juan Francisco

    2015-12-01

    Polymer membranes are prepared as a composite of polybenzimidazole and non-functionalized multiwall carbon nanotubes (PBI-CNT) and polybenzimidazole (PBI) only. Each is doped with H3PO4 (PA) and used as a proton exchange membrane (PEM) as the electrolyte in a fuel cell. The proton conductivities at 180 °C for the doped PBI membrane (PBIPA) and the doped PBI-CNT membrane (PBICNTPA) are 6.3 × 10-2 and 7.4 × 10-2 Scm-1 respectively. A single fuel cell having these membranes as electrolyte has a Pt catalyzed hydrogen gas fed anode and a similar oxygen cathode without humidification of feed gases; the cell with the PBICNTPA membrane has higher open circuit voltage (0.96 V) than that with a PBIPA membrane (0.8 V) at 180 °C. The mechanical stability of the membrane improves with CNTs addition. The tensile strength of the composite PBI-CNT membrane with 1 wt.% CNTs loading is 32% higher and the Young's Modulus is 147% higher than the values for a membrane of PBI alone. The improvement in conductivity and mechanical properties in the composite membrane due to the CNT addition indicates that a PBI-CNT membrane is a good alternative as a membrane electrolyte in a PEMFC.

  12. Transformation of metal-organic frameworks for molecular sieving membranes

    NASA Astrophysics Data System (ADS)

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-04-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

  13. Transformation of metal-organic frameworks for molecular sieving membranes

    PubMed Central

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-01-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively. PMID:27090597

  14. Nanofiber Composite Membranes for Alkaline Fuel Cells: Generation of Compositional, Morphological, and Functional Property Relationships

    DTIC Science & Technology

    2015-12-01

    properties of nanofiber composite anion-exchange membranes for alkaline fuel cells. A new membrane fabrication strategy, utilizing polymer fiber...electrospinning, will be employed to make hydroxide-conducting membranes with an entirely new morphology, where one electrospun polymer provides pathways...for ion conductivity and the second electrospun polymer restricts ionomer swelling and imparts mechanical strength to the membrane. The functional

  15. Poly(acrylonitrile)chitosan composite membranes for urease immobilization.

    PubMed

    Gabrovska, Katya; Georgieva, Aneliya; Godjevargova, Tzonka; Stoilova, Olya; Manolova, Nevena

    2007-05-10

    (Poly)acrylonitrile/chitosan (PANCHI) composite membranes were prepared. The chitosan layer was deposited on the surface as well as on the pore walls of the base membrane. This resulted in the reduction of the pore size of the membrane and in an increase of their hydrophilicity. The pore structure of PAN and PANCHI membranes were determined by TEM and SEM analyses. It was found that the average size of the pore under a selective layer base PAN membrane is 7 microm, while the membrane coated with 0.25% chitosan shows a reduced pore size--small or equal to 5 microm and with 0.35% chitosan--about 4 microm. The amounts of the functional groups, the degree of hydrophilicity and transport characteristics of PAN/Chitosan composite membranes were determined. Urease was covalently immobilized onto all kinds of PAN/chitosan composite membranes using glutaraldehyde. Both the amount of bound protein and relative activity of immobilized urease were measured. The highest activity (94%) was measured for urease bound to PANCHI2 membranes (0.25% chitosan). The basic characteristics (pH(opt), pH(stability), T(opt), T(stability), heat inactivation and storage stability) of immobilized urease were determined. The obtained results show that the poly(acrylonitrile)chitosan composite membranes are suitable for enzyme immobilization.

  16. High performance thin-film composite forward osmosis membrane.

    PubMed

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A; Schiffman, Jessica D; Elimelech, Menachem

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 mum) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m(2-)h(-1), while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution.

  17. Synthesis and characterization of functionalized silica/SPES composite membranes

    NASA Astrophysics Data System (ADS)

    Gahlot, Swati; Sharma, Prem Prakash; Kulshrestha, Vaibhav

    2015-06-01

    Mesoporous silica (MCM-41) has been synthesized via sol gel route. Sulfonation of MCM-41 has been done. Synthesized Sulfonated MCM-41 (S-MCM-41) has been incorporated within SPES (sulfonated poly ether sulfone) polymer matrix to prepare composite membranes. Various concentration of S-MCM-41 has been incorporated into SPES i.e. 1, 2, 5, 10 and 20 wt% to synthesize membranes of different wt% of mesoporous silica. FTIR and XRD of MCM-41 and S-MCM-41 were done to confirm the chemical and structural properties. AFM and UTM are used to find out morphology and mechanical properties of the composites. The water uptake and ionic conductivity of the composite membranes increases with MCM content in composite membrane. Mechanical stability of the membrane also found to be increases with MCM content.

  18. Preparation and performance of nano silica/Nafion composite membrane for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Keping; McDermid, Scott; Li, Jing; Kremliakova, Natalia; Kozak, Paul; Song, Chaojie; Tang, Yanghua; Zhang, Jianlu; Zhang, Jiujun

    Composite membranes made from Nafion ionomer with nano phosphonic acid-functionalised silica and colloidal silica were prepared and evaluated for proton exchange membrane fuel cells (PEMFCs) operating at elevated temperature and low relative humidity (RH). The phosphonic acid-functionalised silica additive obtained from a sol-gel process was well incorporated into Nafion membrane. The particle size determined using transmission electron microscope (TEM) had a narrow distribution with an average value of approximately 11 nm and a standard deviation of ±4 nm. The phosphonic acid-functionalised silica additive enhanced proton conductivity and water retention by introducing both acidic groups and porous silica. The proton conductivity of the composite membrane with the acid-functionalised silica was 0.026 S cm -1, 24% higher than that of the unmodified Nafion membrane at 85 °C and 50% RH. Compared with the Nafion membrane, the phosphonic acid-functionalised silica (10% loading level) composite membrane exhibited 60 mV higher fuel cell performance at 1 A cm -2, 95 °C and 35% RH, and 80 mV higher at 0.8 A cm -2, 120 °C and 35% RH. The fuel cell performance of composite membrane made with 6% colloidal silica without acidic group was also higher than unmodified Nafion membrane, however, its performance was lower than the acid-functionalised silica additive composite membrane.

  19. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    SciTech Connect

    Haryadi, Sugianto, D.; Ristopan, E.

    2015-12-29

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm{sup −1} and 3300 cm{sup −1} respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10{sup −2} S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

  20. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Haryadi, Sugianto, D.; Ristopan, E.

    2015-12-01

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm-1 and 3300 cm-1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10-2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

  1. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  2. Metal-containing lubricant compositions

    SciTech Connect

    Hunt, M.W.; Kennedy, S.

    1987-05-12

    A lubricating oil composition is described comprising: a major amount of a lubricating oil; from 1 to 10 (wt)% of an ashless dispersant compound; or from 0.3 to 10 (wt)% of a nitrogen or ester containing polymeric viscosity index improver dispersant.

  3. Separation membranes. Interfacial microfluidic processing of metal-organic framework hollow fiber membranes.

    PubMed

    Brown, Andrew J; Brunelli, Nicholas A; Eum, Kiwon; Rashidi, Fereshteh; Johnson, J R; Koros, William J; Jones, Christopher W; Nair, Sankar

    2014-07-04

    Molecular sieving metal-organic framework (MOF) membranes have great potential for energy-efficient chemical separations, but a major hurdle is the lack of a scalable and inexpensive membrane fabrication mechanism. We describe a route for processing MOF membranes in polymeric hollow fibers, combining a two-solvent interfacial approach for positional control over membrane formation (at inner and outer surfaces, or in the bulk, of the fibers), a microfluidic approach to replenishment or recycling of reactants, and an in situ module for membrane fabrication and permeation. We fabricated continuous molecular sieving ZIF-8 membranes in single and multiple poly(amide-imide) hollow fibers, with H2/C3H8 and C3H6/C3H8 separation factors as high as 370 and 12, respectively. We also demonstrate positional control of the ZIF-8 films and characterize the contributions of membrane defects and lumen bypass.

  4. Electrochemical Synthesis of Ultrathin Film Composite Membranes

    DTIC Science & Technology

    1993-10-27

    Nicholson, M. S., "Effect of Polymer Electrode Morphology on Performance of a Lithium /Polypyrrole Battery ," May 1991. 2. Chao Liu, Ph. D., "Development... applications including uses in electrochemical science (1) and in membrane- based separations (2). The membrane typically acts as a selective barrier... applications , the membrane is asked to transport a specific ionic species (e.g. OH- (3)) from one half-cell to another and reject all other ions

  5. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    NASA Technical Reports Server (NTRS)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  6. Heterogeneity in Lipid Composition of the Outer Membrane and Cytoplasmic Membrane of Pseudomonas BAL-31

    PubMed Central

    Diedrich, D. L.; Cota-Robles, E. H.

    1974-01-01

    The outer membranes and cytoplasmic membranes of the marine bacterium Pseudomonas BAL-31 were separated by washing the cells three times in 0.5 M NaCl and twice in 0.5 M sucrose. Electron microscopy during the removal of membranes revealed that the outer membranes fragmented in a regular manner to give rise to fairly uniform vesicles measuring approximately 140 nm in diameter. Isolated outer membranes had a buoyant density in sucrose of 1.230 g per cm3, whereas the cytoplasmic membranes had a density of 1.194 g per cm3. The removal of the outer membrane during the application of this procedure was monitored by measuring the release of 2-keto-3-deoxyoctulosonic acid and phospholipid. The cells lost 85.5% of their 2-keto-3-deoxyoctulosonic acid and 47.3% of their phospholipid during this treatment. Complete recovery of outer membrane material could be achieved. The removal of 25.5% of the 2-keto-3-deoxyoctulosonic acid and 0.9% of the phospholipid rendered the cells sensitive to lysis with Triton X-100. The phospholipid composition of the outer membrane was calculated to be 78.9% phosphatidylethanolamine and 16.1% phosphatidylglycerol. The phospholipid composition of the cytoplasmic membrane proved to be 71.5% phosphatidylethanolamine and 23.5% phosphatidylglycerol. The fatty acid composition was also found to be quantitatively heterogeneous between the two membranes. Images PMID:4852262

  7. Composite membranes, methods of making same, and applications of same

    SciTech Connect

    Pintauro, Peter N.; Park, Andrew; Ballengee, Jason

    2016-05-24

    In one aspect of the present invention, a method of fabricating a composite membrane includes: forming a first polymer solution from a first polymer and a second polymer solution from a second polymer, respectively, where the first polymer includes a charged polymer and the second polymer includes an uncharged polymer; electrospinning, separately and simultaneously, the first and second polymer solutions to form a dual fiber mat with first polymer fibers and second polymer fibers; and processing the dual fiber mat by softening and flowing one of the first or second polymer fibers to fill in the void space between the other of the first and second polymer fibers so as to form the composite membrane. In some embodiments, the composite membrane may be a proton exchange membrane (PEM) or an anion exchange membrane (AEM).

  8. Palladium/Copper Alloy Composite Membranes for High Temperature Hydrogen Separation

    SciTech Connect

    J. Douglas Way; Paul M. Thoen

    2006-08-31

    This report summarizes progress made during the a three year University Coal Research grant (DEFG26-03NT41792) at the Colorado School of Mines. The period of performance was September 1, 2003 through August of 2006. We made excellent progress toward our goal of contributing to the development of high productivity, sulfur tolerant composite metal membranes for hydrogen production and membrane reactors. Composite Pd and Pd alloy metal membranes with thin metal films (1-7 {micro}m) were prepared on porous stainless steel and ceramic supports that meet or exceed the DOE 2010 and 2015 pure hydrogen flux targets at differential pressure of only 20 psi. For example, a 2 {micro}m pure Pd membrane on a Pall AccuSep{reg_sign} substrate achieved an ideal H{sub 2}/N{sub 2} separation factor of over 6000, with a pure hydrogen flux of 210 SCFH/ft{sup 2} at only 20 psig feed pressure. Similar performance was achieved with a Pd{sub 80}Au{sub 20} composite membrane on a similar stainless steel substrate. Extrapolating the pure hydrogen flux of this PdAu membrane to the DOE Fossil Energy target conditions of 150 psia feed pressure and 50 psia permeate pressure gives a value of 508 SCFH/ft{sup 2}, exceeding the 2015 target. At these thicknesses, it is the support cost that will dominate the cost of a large scale module. In a direct comparison of FCC phase PdCu and PdAu alloys on identical supports, we showed that a Pd{sub 85}Au{sub 15} (mass %) alloy membrane is not inhibited by CO, CO{sub 2}, or steam present in a water-gas shift feed mixture at 400 C, has better resistance to sulfur than a Pd{sub 94}Cu{sub 6} membrane, and has over twice the hydrogen permeance.

  9. Metal-metal laminar composites for high temperature applications

    NASA Technical Reports Server (NTRS)

    Hoffman, C. A.; Weeton, J. W.

    1972-01-01

    A study was conducted to obtain indications of the potentialities of laminar metal-metal composites for elevated temperature use. Most of the composites consisted of multiple layers or laminae of tungsten alternated with laminae of Nichrome V, a ductile, weaker but oxidation-resistant alloy. Composites with 50 volume percent of each phase were tested in tension and stress rupture at temperatures of 871 and 1093 C (1600 and 2000 F) and in impact at 23 and 524 C (73 and 975 F). A tension and a short time stress-rupture test was conducted on specimens of 77 v/o W-Re-Hf-C/23 v/o Inconel alloy 600 at 1093 C (2000 F).

  10. METCAN-PC - METAL MATRIX COMPOSITE ANALYZER

    NASA Technical Reports Server (NTRS)

    Murthy, P. L.

    1994-01-01

    High temperature metal matrix composites offer great potential for use in advanced aerospace structural applications. The realization of this potential however, requires concurrent developments in (1) a technology base for fabricating high temperature metal matrix composite structural components, (2) experimental techniques for measuring their thermal and mechanical characteristics, and (3) computational methods to predict their behavior. METCAN (METal matrix Composite ANalyzer) is a computer program developed to predict this behavior. METCAN can be used to computationally simulate the non-linear behavior of high temperature metal matrix composites (HT-MMC), thus allowing the potential payoff for the specific application to be assessed. It provides a comprehensive analysis of composite thermal and mechanical performance. METCAN treats material nonlinearity at the constituent (fiber, matrix, and interphase) level, where the behavior of each constituent is modeled accounting for time-temperature-stress dependence. The composite properties are synthesized from the constituent instantaneous properties by making use of composite micromechanics and macromechanics. Factors which affect the behavior of the composite properties include the fabrication process variables, the fiber and matrix properties, the bonding between the fiber and matrix and/or the properties of the interphase between the fiber and matrix. The METCAN simulation is performed as point-wise analysis and produces composite properties which are readily incorporated into a finite element code to perform a global structural analysis. After the global structural analysis is performed, METCAN decomposes the composite properties back into the localized response at the various levels of the simulation. At this point the constituent properties are updated and the next iteration in the analysis is initiated. This cyclic procedure is referred to as the integrated approach to metal matrix composite analysis. METCAN

  11. Self-Healing Metals and Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Ferguson, J. B.; Schultz, Benjamin F.; Rohatgi, Pradeep K.

    2014-06-01

    Self-healing in inorganic materials is a relatively new area in materials science and engineering that draws inspiration from biological systems that can self-repair damage. This article reviews the preliminary attempts to impart self-healing behavior to metals. Several challenges yet exist in the development of metallic alloys that can self-repair damage, including surface bonding issues, such as liquid/solid contact angle (wetting) and oxidation, and practical issues, such as capillary pressure for delivery of a liquid metal to a damaged area or crack, and the overall mechanical properties of a composite system. Although the applied research approaches reviewed have obtained marginal success, the development of self-healing metallic systems has the potential to benefit a wide range of industrial applications and thus deserves greater investment in fundamental research.

  12. Novel amine-based presursor compounds and composite membranes thereof

    DOEpatents

    Lee, Eric K. L.; Tuttle, Mark E.

    1989-01-01

    Novel amine-based precursor compounds comprising the condensation products of dialkylenetriamine and alpha, beta-unsaturated acid halides are disclosed, as well as composite membranes containing such compounds, the membranes being useful in RO-type processes for desalination and the removal of low molecular weight organic compounds such as phenols and carboxylic acids.

  13. Resin infusion of layered metal/composite hybrid and resulting metal/composite hybrid laminate

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J. (Inventor); Grimsley, Brian W. (Inventor); Weiser, Erik S. (Inventor); Jensen, Brian J. (Inventor)

    2009-01-01

    A method of fabricating a metal/composite hybrid laminate is provided. One or more layered arrangements are stacked on a solid base to form a layered structure. Each layered arrangement is defined by a fibrous material and a perforated metal sheet. A resin in its liquid state is introduced along a portion of the layered structure while a differential pressure is applied across the laminate structure until the resin permeates the fibrous material of each layered arrangement and fills perforations in each perforated metal sheet. The resin is cured thereby yielding a metal/composite hybrid laminate.

  14. Composite plasma polymerized sulfonated polystyrene membrane for PEMFC

    SciTech Connect

    Nath, Bhabesh Kumar; Khan, Aziz; Chutia, Joyanti

    2015-10-15

    Highlights: • Methyl methane sulfonate (MMS) is used as the sulfonating agent. • The proton conductivity of the membrane is found to be 0.141 S cm{sup −1}. • Power density of fuel cell with styrene/MMS membrane is 0.5 W cm{sup −2}. • The membrane exhibits thermal stability up to 140 °C. - Abstract: This work presents the introduction of an organic compound methyl methane sulfonate (MMS) for the first time in fabrication of polystyrene based proton exchange membrane (PEM) by plasma polymerization process. The membrane is fabricated by co-polymerizing styrene and MMS in capacitively coupled continuous RF plasma. The chemical composition of the plasma polymerized polymer membrane is investigated using Fourier Transform Infrared Spectroscopy which reveals the formation of composite structure of styrene and MMS. The surface morphology studied using AFM and SEM depicts the effect of higher partial pressure of MMS on surface topography of the membrane. The proton transport property of the membrane studied using electrochemical impedance spectroscopy shows the achievement of maximum proton conductivity of 0.141 S cm{sup −1} which is comparable to Nafion 117 membrane. Fuel cell performance test of the synthesized membrane shows a maximum power density of 500 mW cm{sup −2} and current density of 0.62 A cm{sup −2} at 0.6 V.

  15. Micromechanical Modeling of Woven Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Pindera, Marek-Jerzy

    1997-01-01

    This report presents the results of an extensive micromechanical modeling effort for woven metal matrix composites. The model is employed to predict the mechanical response of 8-harness (8H) satin weave carbon/copper (C/Cu) composites. Experimental mechanical results for this novel high thermal conductivity material were recently reported by Bednarcyk et al. along with preliminary model results. The micromechanics model developed herein is based on an embedded approach. A micromechanics model for the local (micro-scale) behavior of the woven composite, the original method of cells (Aboudi), is embedded in a global (macro-scale) micromechanics model (the three-dimensional generalized method of cells (GMC-3D) (Aboudi). This approach allows representation of true repeating unit cells for woven metal matrix composites via GMC-3D, and representation of local effects, such as matrix plasticity, yarn porosity, and imperfect fiber-matrix bonding. In addition, the equations of GMC-3D were reformulated to significantly reduce the number of unknown quantities that characterize the deformation fields at the microlevel in order to make possible the analysis of actual microstructures of woven composites. The resulting micromechanical model (WCGMC) provides an intermediate level of geometric representation, versatility, and computational efficiency with respect to previous analytical and numerical models for woven composites, but surpasses all previous modeling work by allowing the mechanical response of a woven metal matrix composite, with an elastoplastic matrix, to be examined for the first time. WCGMC is employed to examine the effects of composite microstructure, porosity, residual stresses, and imperfect fiber-matrix bonding on the predicted mechanical response of 8H satin C/Cu. The previously reported experimental results are summarized, and the model predictions are compared to monotonic and cyclic tensile and shear test data. By considering appropriate levels of porosity

  16. Metallic and intermetallic-bonded ceramic composites

    SciTech Connect

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B.

    1995-05-01

    The purpose of this task is to establish a framework for the development and fabrication of metallic-phase-reinforced ceramic matrix composites with improved fracture toughness and damage resistance. The incorporation of metallic phases that plastically deform in the crack tip region, and thus dissipate strain energy, will result in an increase in the fracture toughness of the composite as compared to the monolithic ceramic. It is intended that these reinforced ceramic matrix composites will be used over a temperature range from 20{degrees}C to 800-1200{degrees}C for advanced applications in the industrial sector. In order to systematically develop these materials, a combination of experimental and theoretical studies must be undertaken.

  17. Robust Polymer Composite Membranes for Hydrogen Separation

    SciTech Connect

    2009-11-01

    This factsheet describes a research project whose primary goal is to achieve a major improvement in the combined economics and performance of polymenzimidazole-based (PBI) membrane technology in the application of hydrogen separation from a syngas stream.

  18. Antimicrobial metallic copper surfaces kill Staphylococcus haemolyticus via membrane damage

    PubMed Central

    Santo, Christophe Espírito; Quaranta, Davide; Grass, Gregor

    2012-01-01

    Recently, copper (Cu) in its metallic form has regained interest for its antimicrobial properties. Use of metallic Cu surfaces in worldwide hospital trials resulted in remarkable reductions in surface contaminations. Yet, our understanding of why microbes are killed upon contact to the metal is still limited and different modes of action have been proposed. This knowledge, however, is crucial for sustained use of such surfaces in hospitals and other hygiene-sensitive areas. Here, we report on the molecular mechanisms by which the Gram-positive Staphylococcus haemolyticus is inactivated by metallic Cu. Staphylococcus haemolyticus was killed within minutes on Cu but not on stainless steel demonstrating the antimicrobial efficacy of metallic Cu. Inductively coupled plasma mass spectroscopy (ICP-MS) analysis and in vivo staining with Coppersensor-1 indicated that cells accumulated large amounts of Cu ions from metallic Cu surfaces contributing to lethal damage. Mutation rates of Cu- or steel-exposed cells were similarly low. Instead, live/dead staining indicated cell membrane damage in Cu- but not steel-exposed cells. These findings support a model of the cellular targets of metallic Cu toxicity in bacteria, which suggests that metallic Cu is not genotoxic and does not kill via DNA damage. In contrast, membranes constitute the likely Achilles’ heel of Cu surface-exposed cells. PMID:22950011

  19. Fabrication of bioinspired composite nanofiber membranes with robust superhydrophobicity for direct contact membrane distillation.

    PubMed

    Liao, Yuan; Wang, Rong; Fane, Anthony G

    2014-06-03

    The practical application of membrane distillation (MD) for water purification is hindered by the absence of desirable membranes that can fulfill the special requirements of the MD process. Compared to the membranes fabricated by other methods, nanofiber membranes produced by electrospinning are of great interest due to their high porosity, low tortuosity, large surface pore size, and high surface hydrophobicity. However, the stable performance of the nanofiber membranes in the MD process is still unsatisfactory. Inspired by the unique structure of the lotus leaf, this study aimed to develop a strategy to construct superhydrophobic composite nanofiber membranes with robust superhydrophobicity and high porosity suitable for use in MD. The newly developed membrane consists of a superhydrophobic silica-PVDF composite selective skin formed on a polyvinylidene fluoride (PVDF) porous nanofiber scaffold via electrospinning. This fabrication method could be easily scaled up due to its simple preparation procedures. The effects of silica diameter and concentration on membrane contact angle, sliding angle, and MD performance were investigated thoroughly. For the first time, the direct contact membrane distillation (DCMD) tests demonstrate that the newly developed membranes are able to present stable high performance over 50 h of testing time, and the superhydrophobic selective layer exhibits excellent durability in ultrasonic treatment and a continuous DCMD test. It is believed that this novel design strategy has great potential for MD membrane fabrication.

  20. Lipid exchange between membranes: effects of membrane surface charge, composition, and curvature.

    PubMed

    Zhu, Tao; Jiang, Zhongying; Ma, Yuqiang

    2012-09-01

    Intermembrane lipid exchange is critical to membrane functions and pharmaceutical applications. The exchange process is not fully understood and it is explored by quartz crystal microbalance with dissipation monitor method in this research. It is found that intermembrane lipid exchange is accelerated with the decrease of vesicle size and the increase of charge and liquid crystalline lipid composition ratio. Vesicle adsorption rate, membrane lateral pressure gradient, and lipid lateral diffusion coefficient are inferred to be critical in deciding the lipid exchange kinetics between membranes. Besides that, the membrane contact situation during lipid exchange is also studied. The maximum total membrane contact area is found to increase with the decrease of vesicle size, charged and liquid crystalline lipid composition ratio. A competition mechanism between the vesicle adsorption rate and the intermembrane lipid exchange rate was proposed to control the maximum total membrane contact area.

  1. Separation of tritiated water from water using composite membranes

    SciTech Connect

    Duncan, J.; Nelson, D.

    1996-10-01

    Polymeric composite membranes are being developed to remove tritium from contaminated water at DOE sites. Industrial membrane systems are being developed that have proven to be energy efficient, and membrane technologies such as reverse-osmosis have been well developed for desalination and other industrial/municipal applications. Aromatic polyphosphazene membranes are being investigated because they have excellent radiological, thermal, and chemical stability. The FY 1996 effort is directed toward delineating a potential mechanism, providing a statistical approach to data acquisition, refining a mass balance, and designing a staged array module.

  2. SEPARATION OF TRITIATED WATER FROM WATER USING COMPOSITE MEMBRANES

    SciTech Connect

    DUNCAN JB; NELSON DA

    1995-12-18

    The work in this task involves the use of composite membranes to remove tritium from contaminated water at DOE sites. Experience with membrane systems in industry indicates that they are inherently energy efficient. Furthermore, membrane technologies such as reverse-osmosis have been well developed for desalination and other industrial/municipal applications. Aromatic polyphosphazenes were chosen as the polymeric material for the membranes being investigated because they have excellent radiological, thermal, and chemical stability. The FY-96 effort is directed toward empirical delineation of a potential mechanism, providing a statistical approach to data acquisition, further mass balance determination, and a preliminary design for the module staged array.

  3. Metal-polymer composites comprising nanostructures and applications thereof

    DOEpatents

    Wang, Hsing-Lin [Los Alamos, NM; Jeon, Sea Ho [Dracut, MA; Mack, Nathan H [Los Alamos, NM

    2012-04-03

    Metal-polymer composites, and methods of making and use thereof, said composites comprising a thermally-cured dense polyaniline substrate; an acid dopant; and, metal nanostructure deposits wherein the deposits have a morphology dependent upon the acid dopant.

  4. Metal-polymer composites comprising nanostructures and applications thereof

    DOEpatents

    Wang, Hsing-Lin; Jeon, Sea Ho; Mack, Nathan H.

    2011-08-02

    Metal-polymer composites, and methods of making and use thereof, said composites comprising a thermally-cured dense polyaniline substrate; an acid dopant; and, metal nanostructure deposits wherein the deposits have a morphology dependent upon the acid dopant.

  5. TUNABLE COMPOSITE MEMBRANES FOR GAS SEPARATIONS

    SciTech Connect

    J.P. Ferraris; K.J. Balkus, Jr.; I.H. Musselman

    1999-01-01

    Poly 2-(3-thienyl)ethylacetate (PAET) was synthesized and solution cast as thin films to form dense membranes. These membranes are mechanically robust and are redox active, holding out promise as gas separation materials. The permeability properties of PAET membranes were evaluated for N{sub 2} (0.048 {+-} 0.008 Barrers), O{sub 2} (0.24 {+-} 0.02 Barrers), CH{sub 4} (0.081 {+-} 0.005 Barrers), and CO{sub 2} (1.4 {+-} 0.1 Barrers). The corresponding selectivity values ({alpha}) were: O{sub 2}/N{sub 2} = 5.1, CO{sub 2}/N{sub 2} = 29, and CO{sub 2}/CH{sub 4} = 18.

  6. Preparation of Chitosan/Polystyrene Sulfonate Multilayered Composite Metal Nanoparticles and Its Application.

    PubMed

    Xiong, Fangxin; Chen, Chunxiao; Liu, Shantang

    2016-06-01

    Metal-Chitosan (CTS) composite was first synthesized through the metal composition of chitosan (CTS) and metal ions. The formed composite was alternately deposited on the base with sodium polystyrene sulfonate (PSS) through a layer-by-layer self-assembling technique, followed by an in situ reduction by sodium borohydride to produce a polyelectrolyte nanocomposite thin film containing metal nanoparticles. Assembly, surface morphology and electrochemical properties of the composite membrane were analyzed by UV-visible absorption spectroscopy (UV-vis), atomic force microscopy (AFM) and cyclic voltammetry (CV). The UV-Vis results indicated that the absorbance of the multilayer film at the characteristic absorption peak increased as the membrane bilayers increased, in a good linear relationship, which demonstrated that the multilayer film was uniformly assembled on the base. AFM images showed that the surface of the multilayer thin-film composite had some degree of roughness and metal nanoparticles of 10-20 nm in size were generated on the membrane. The CV results indicated that the metal nanocomposite film had excellent electrocatalytic activity to glucose and had a potential for applications in electrochemical sensors.

  7. Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

    SciTech Connect

    Way, J.; Wolden, Colin

    2013-09-30

    Colorado School of Mines (CSM) developed high temperature, hydrogen permeable membranes that contain no platinum group metals with the goal of separating hydrogen from gas mixtures representative of gasification of carbon feedstocks such as coal or biomass in order to meet DOE NETL 2015 hydrogen membrane performance targets. We employed a dual synthesis strategy centered on transition metal carbides. In the first approach, novel, high temperature, surface diffusion membranes based on nanoporous Mo{sub 2}C were fabricated on ceramic supports. These were produced in a two step process that consisted of molybdenum oxide deposition followed by thermal carburization. Our best Mo{sub 2}C surface diffusion membrane achieved a pure hydrogen flux of 367 SCFH/ft{sup 2} at a feed pressure of only 20 psig. The highest H{sub 2}/N{sub 2} selectivity obtained with this approach was 4.9. A transport model using “dusty gas” theory was derived to describe the hydrogen transport in the Mo{sub 2}C coated, surface diffusion membranes. The second class of membranes developed were dense metal foils of BCC metals such as vanadium coated with thin (< 60 nm) Mo{sub 2}C catalyst layers. We have fabricated a Mo{sub 2}C/V composite membrane that in pure gas testing delivered a H{sub 2} flux of 238 SCFH/ft{sup 2} at 600 °C and 100 psig, with no detectable He permeance. This exceeds the 2010 DOE Target flux. This flux is 2.8 times that of pure Pd at the same membrane thickness and test conditions and over 79% of the 2015 flux target. In mixed gas testing we achieved a permeate purity of ≥99.99%, satisfying the permeate purity milestone, but the hydrogen permeance was low, ~0.2 SCFH/ft{sup 2}.psi. However, during testing of a Mo{sub 2}C coated Pd alloy membrane with DOE 1 feed gas mixture a hydrogen permeance of >2 SCFH/ft{sup 2}.psi was obtained which was stable during the entire test, meeting the permeance associated with the 2010 DOE target flux. Lastly, the Mo{sub 2}C/V composite

  8. Metal mesh scaffold for tissue engineering of membranes.

    PubMed

    Alavi, S Hamed; Kheradvar, Arash

    2012-04-01

    Engineering of the membrane-like tissue structures to be utilized in highly dynamic loading environments such as the cardiovascular system has been a challenge in the past decade. Scaffolds are critical components of the engineered tissue membranes and allow them being formed in vitro and remain secure in vivo when implanted in the body. Several approaches have been taken to develop scaffolds for tissue membranes. However, all methods entail limitations due to structural vulnerability, short-term functionality, and mechanical properties of the resulted membrane constructs. To overcome these issues, we have developed a novel hybrid scaffold made of an extra thin layer of metal mesh tightly enclosed by biological matrix components. This approach retains all the advantages of using biological scaffolds while developing a strong extracellular matrix that can stand various types of loads after implantation inside the body.

  9. Emissivity of freestanding membranes with thin metal coatings

    SciTech Connect

    Zwol, P. J. van Vles, D. F.; Voorthuijzen, W. P.; Péter, M.; Vermeulen, H.; Zande, W. J. van der; Sturm, J. M.; Kruijs, R. W. E. van de; Bijkerk, F.

    2015-12-07

    Freestanding silicon nitride membranes with thicknesses down to a few tens of nanometers find use as TEM windows or soft X-ray spectral purity filters. As the thickness of a membrane decreases, emissivity vanishes, which limits radiative heat emission and resistance to heat loads. We show that thin metal layers with thicknesses in the order of 1 nm enhance the emissivity of thin membranes by two to three orders of magnitude close to the theoretical limit of 0.5. This considerably increases thermal load capacity of membranes in vacuum environments. Our experimental results are in line with classical theory in which we adapt thickness dependent scattering terms in the Drude and Lorentz oscillators.

  10. Metal-organic frameworks for membrane-based separations

    NASA Astrophysics Data System (ADS)

    Denny, Michael S.; Moreton, Jessica C.; Benz, Lauren; Cohen, Seth M.

    2016-12-01

    As research into metal-organic frameworks (MOFs) enters its third decade, efforts are naturally shifting from fundamental studies to applications, utilizing the unique features of these materials. Engineered forms of MOFs, such as membranes and films, are being investigated to transform laboratory-synthesized MOF powders to industrially viable products for separations, chemical sensors and catalysts. Following encouraging demonstrations of gas separations using MOF-based membranes, liquid-phase separations are now being explored in an effort to build effective membranes for these settings. In this Review, we highlight MOF applications that are in their nascent stages, specifically liquid-phase separations using MOF-based mixed-matrix membranes. We also highlight the analytical techniques that provide important insights into these materials, particularly at surfaces and interfaces, to better understand MOFs and their interactions with other materials, which will ultimately lead to their use in advanced technologies.

  11. Anionically-Conductive Ultrathin Film Composite Membranes

    DTIC Science & Technology

    1994-08-19

    these polymers in pervaporation separations. The interfacial polymerizations we have developed are used to prepare ultrathin films of conductive... pervaporation -separations, etc. We are continuing this research effort by exploring in particular sensor and pervaporation applications of these coated...particular emphasis are in novel biosensors and novel membranes for pervaporation separations. IV. Research Articles. 1. Lei, J.; Menon, V. P.; Martin, C. R

  12. Microwave Absorbing Properties of Metallic Glass/Polymer Composites

    DTIC Science & Technology

    2011-09-01

    Technical Report ARWSB-TR-11022 Microwave Absorbing Properties of Metallic Glass/Polymer Composites Stephen Bartolucci...Technical 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Microwave Absorbing Properties of Metallic Glass/Polymer Composites 5a. CONTRACT...this study, the microwave absorption characteristics of metallic glass / polymer composites were investigated. Electromagnetic wave absorption

  13. Alkali metal protective garment and composite material

    DOEpatents

    Ballif, III, John L.; Yuan, Wei W.

    1980-01-01

    A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

  14. Designing a New Class of Electrocatalysts for Polymer Electrolyte Membrane Fuel Cells: Probing Size, Composition, and Structure Dependent Electrocatalytic Performance in High-Quality, One-Dimensional Noble Metal Nanostructures

    NASA Astrophysics Data System (ADS)

    Koenigsmann, Christopher

    A key challenge in the practical commercialization of PEMFCs is the extremely high cost and relatively poor durability of carbon supported Pt nanoparticle (Pt NP/C) electrocatalysts utilized in both the anode and cathode half-cells. Herein, we synthesize and characterize a new class of high-quality one-dimensional noble metal nanostructures as a potentially new and promising structural paradigm for the next generation of electrocatalyst materials. Specifically, we investigate the nature of the complex interplay amongst size, chemical composition, and electrocatalytic performance in high-quality elemental and bimetallic 1D noble metal nanowire systems with an emphasis on achieving efficient and sustainable methods for catalyst preparation. In terms of nanowire dimensions and composition, an interesting and measureable size-dependent enhancement in performance emerges in the case of elemental Pt, Pd, and Pd1-xAux nanowires possessing diameters ranging from the submicron (d = ˜200 nm) to the ultrathin regime (d = ˜1 nm). In a similar context, we have considered the role of chemical composition in 1D electrocatalysts and noted significant composition-dependent enhancements in activity and durability in high-quality, bimetallic Pd1-xAux and Pd1-xPtx NWs. A key finding that is apparent from these experimental results is that widely seen behavioral trends in the composition- and size-dependent performance for 0D nanoparticle-based catalysts do not hold in the case of 1D architectures, because of the patently unique structural and electronic effects, associated with their anisotropic structures. As a culmination of our efforts to take advantage of these intrinsic structure-activity correlations, our group has developed a morphology-, size-, and composition-optimized Pd9Au NW possessing a Pt monolayer shell (PtML˜Pd9Au NWs) electrocatalyst with an ultrathin 2 nm diameter, which yielded outstanding Pt mass and platinum group metal activities of 2.56 A/mgPt and 0.64 A

  15. Interaction of Spin-Labeled Lipid Membranes with Transition Metal Ions

    PubMed Central

    2015-01-01

    The large values of spin relaxation enhancement (RE) for PC spin-labels in the phospholipid membrane induced by paramagnetic metal salts dissolved in the aqueous phase can be explained by Heisenberg spin exchange due to conformational fluctuations of the nitroxide group as a result of membrane fluidity, flexibility of lipid chains, and, possibly, amphiphilic nature of the nitroxide label. Whether the magnetic interaction occurs predominantly via Heisenberg spin exchange (Ni) or by the dipole–dipole (Gd) mechanism, it is essential for the paramagnetic ion to get into close proximity to the nitroxide moiety for efficient RE. For different salts of Ni the RE in phosphatidylcholine membranes follows the anionic Hofmeister series and reflects anion adsorption followed by anion-driven attraction of paramagnetic cations on the choline groups. This adsorption is higher for chaotropic ions, e.g., perchlorate. (A chaotropic agent is a molecule in water solution that can disrupt the hydrogen bonding network between water molecules.) However, there is no anionic dependence of RE for model membranes made from negatively charged lipids devoid of choline groups. We used Ni-induced RE to study the thermodynamics and electrostatics of ion/membrane interactions. We also studied the effect of membrane composition and the phase state on the RE values. In membranes with cholesterol a significant difference is observed between PC labels with nitroxide tethers long enough vs not long enough to reach deep into the membrane hydrophobic core behind the area of fused cholesterol rings. This study indicates one must be cautious in interpreting data obtained by PC labels in fluid membranes in terms of probing membrane properties at different immersion depths when it can be affected by paramagnetic species at the membrane surface. PMID:26490692

  16. Interaction of Spin-Labeled Lipid Membranes with Transition Metal Ions.

    PubMed

    Dzikovski, Boris; Livshits, Vsevolod; Freed, Jack

    2015-10-22

    The large values of spin relaxation enhancement (RE) for PC spin-labels in the phospholipid membrane induced by paramagnetic metal salts dissolved in the aqueous phase can be explained by Heisenberg spin exchange due to conformational fluctuations of the nitroxide group as a result of membrane fluidity, flexibility of lipid chains, and, possibly, amphiphilic nature of the nitroxide label. Whether the magnetic interaction occurs predominantly via Heisenberg spin exchange (Ni) or by the dipole-dipole (Gd) mechanism, it is essential for the paramagnetic ion to get into close proximity to the nitroxide moiety for efficient RE. For different salts of Ni the RE in phosphatidylcholine membranes follows the anionic Hofmeister series and reflects anion adsorption followed by anion-driven attraction of paramagnetic cations on the choline groups. This adsorption is higher for chaotropic ions, e.g., perchlorate. (A chaotropic agent is a molecule in water solution that can disrupt the hydrogen bonding network between water molecules.) However, there is no anionic dependence of RE for model membranes made from negatively charged lipids devoid of choline groups. We used Ni-induced RE to study the thermodynamics and electrostatics of ion/membrane interactions. We also studied the effect of membrane composition and the phase state on the RE values. In membranes with cholesterol a significant difference is observed between PC labels with nitroxide tethers long enough vs not long enough to reach deep into the membrane hydrophobic core behind the area of fused cholesterol rings. This study indicates one must be cautious in interpreting data obtained by PC labels in fluid membranes in terms of probing membrane properties at different immersion depths when it can be affected by paramagnetic species at the membrane surface.

  17. Comparative study of metal induced phospholipid modifications in the heavy metal tolerant filamentous fungus Paecilomyces marquandii and implications for the fungal membrane integrity.

    PubMed

    Słaba, Mirosława; Bernat, Przemysław; Różalska, Sylwia; Nykiel, Justyna; Długoński, Jerzy

    2013-01-01

    In this work we compared the effect of five heavy metals: Zn, Pb, Cd, Ni and Cu on phospholipid composition of the ubiquitous soil fungus Paecilomyces marquandii, originating from a strongly metal polluted area and characterized by high tolerance to these elements. Cd, Ni and Cu caused an increase in phosphatidylcholine (PC). Only Pb decreased PC content, which was accompanied by a significant rise in the phosphatidic acids (PA) level, probably due to activation of phospholipase D which hydrolyzes PC to PA. This could result in membrane fluidity disturbance, and thus affect its integrity. The assessment of propidium iodide influx showed strong disturbance of membrane integrity for Cu and Pb stressed mycelia, whereas mycelia treated with Ni were impermeable to this dye. The results obtained revealed a strong Cu and Pb toxicity involving disruption of membrane integrity. Pb action was reflected by lipid composition, whereas changes in Cu treated mycelia did not completely elucidate its harmful effect on the membrane, which was most probably caused by Cu induced lipid peroxidation. Zn did not induce quantitative changes in PC and phosphatidylethanolamine (PE) but caused changes in phospholipid lipid saturation, which appears to be important for fungus adaptation to the presence of metals. The enhanced PC content balanced by higher PC saturation can help in the maintenance of proper membrane fluidity and result in alleviating the Cd and Ni induced stress. These results will allow to clarify the mechanism of Pb toxicity and help to elucidate the cellular basis of fungal membrane adaptation to heavy metals.

  18. Biosensors Based on Ultrathin Film Composite Membranes

    DTIC Science & Technology

    1994-01-25

    Lehninger , A . L . Principles of Biochemistry, 1st ed.; Worth Publishers, Inc.: New York, 1982. (33) Ouellette, R. J. Introduction to General Organic...Riley, R. L ; Strathmann, H. Membrane Separation Systems - A Research & Development Needs Assessment, Department of Energy: Washington, D.C., 1990...Boguslavsky, L . L ; Inagaki, T.; Karan, H. L ; Lee, H. S.; Skotheim, T. A .; Okamoto, Y. Anal. Chem. 1991, 63(7), 677-682. (12) Gunasingham, H.; Tan, Chin-H.; Seow

  19. Solid polymer electrolyte composite membrane comprising laser micromachined porous support

    DOEpatents

    Liu, Han [Waltham, MA; LaConti, Anthony B [Lynnfield, MA; Mittelsteadt, Cortney K [Natick, MA; McCallum, Thomas J [Ashland, MA

    2011-01-11

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  20. Nanostructured metal-polyaniline composites and applications thereof

    SciTech Connect

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2012-10-02

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  1. Quantitative NDE applied to composites and metals

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S.; Winfree, William P.; Parker, F. Raymond; Heath, D. Michele; Welch, Christopher S.

    1989-01-01

    Research at the NASA/Langley Research Center concerning quantitative NDE of composites and metals is reviewed. The relationship between ultrasonics and polymer cure is outlined. NDE models are presented, which can be used to develop measurement technologies for characterizing the curing of a polymer system for composite materials. The models can be used to determine the glass transition temperature, the degree of cure, and the cure rate. The application of the model to control autoclave processing of composite materials is noted. Consideration is given to the use of thermal diffusion models combined with controlled thermal input measurements to determine the thermal diffusivity of materials. Also, a two-dimensional physical model is described that permits delaminations in samples of Space Shuttle Solid Rocket Motors to be detected in thermograms in the presence of cooling effects and uneven heating.

  2. Liquid Metal Infiltration Processing of Metallic Composites: A Critical Review

    NASA Astrophysics Data System (ADS)

    Sree Manu, K. M.; Ajay Raag, L.; Rajan, T. P. D.; Gupta, Manoj; Pai, B. C.

    2016-10-01

    Metal matrix composites (MMC) are one of the advanced materials widely used for aerospace, automotive, defense, and general engineering applications. MMC can be tailored to have superior properties such as enhanced high-temperature performance, high specific strength and stiffness, increased wear resistance, better thermal and mechanical fatigue, and creep resistance than those of unreinforced alloys. To fabricate such composites with ideal properties, the processing technique has to ensure high volume fraction of reinforcement incorporation, uniform distribution of the reinforcement, and acceptable adhesion between the matrix and the reinforcing phase without unwanted interfacial reactions which degrades the mechanical properties. A number of processing techniques such as stir casting/vortex method, powder metallurgy, infiltration, casting etc. have been developed to synthesize MMC employing a variety of alloy and the reinforcement's combinations. Among these, infiltration process is widely used for making MMC with high volume fraction of reinforcements and offers many more advantages compared to other conventional manufacturing processes. The present paper critically reviews the various infiltration techniques used for making the MMC, their process parameters, characteristics, and selected studies carried out worldwide and by authors on the development of metal ceramic composites by squeeze infiltration process.

  3. Constructing Free Standing Metal Organic Framework MIL-53 Membrane Based on Anodized Aluminum Oxide Precursor

    NASA Astrophysics Data System (ADS)

    Zhang, Yunlu; Gao, Qiuming; Lin, Zhi; Zhang, Tao; Xu, Jiandong; Tan, Yanli; Tian, Weiqian; Jiang, Lei

    2014-05-01

    Metal organic framework (MOF) materials have attracted great attention due to their well-ordered and controllable pores possessing of prominent potentials for gas molecule sorption and separation performances. Organizing the MOF crystals to a continuous membrane with a certain scale will better exhibit their prominent potentials. Reports in recent years concentrate on well grown MOF membranes on specific substrates. Free standing MOF membranes could have more important applications since they are independent from the substrates. However, the method to prepare such a membrane has been a great challenge because good mechanical properties and stabilities are highly required. Here, we demonstrate a novel and facile technique for preparing the free standing membrane with a size as large as centimeter scale. The substrate we use proved itself not only a good skeleton but also an excellent precursor to fulfill the reaction. This kind of membrane owns a strong mechanical strength, based on the fact that it is much thinner than the composite membranes grown on substrates and it could exhibit good property of gas separation.

  4. Constructing Free Standing Metal Organic Framework MIL-53 Membrane Based on Anodized Aluminum Oxide Precursor

    PubMed Central

    Zhang, Yunlu; Gao, Qiuming; Lin, Zhi; Zhang, Tao; Xu, Jiandong; Tan, Yanli; Tian, Weiqian; Jiang, Lei

    2014-01-01

    Metal organic framework (MOF) materials have attracted great attention due to their well-ordered and controllable pores possessing of prominent potentials for gas molecule sorption and separation performances. Organizing the MOF crystals to a continuous membrane with a certain scale will better exhibit their prominent potentials. Reports in recent years concentrate on well grown MOF membranes on specific substrates. Free standing MOF membranes could have more important applications since they are independent from the substrates. However, the method to prepare such a membrane has been a great challenge because good mechanical properties and stabilities are highly required. Here, we demonstrate a novel and facile technique for preparing the free standing membrane with a size as large as centimeter scale. The substrate we use proved itself not only a good skeleton but also an excellent precursor to fulfill the reaction. This kind of membrane owns a strong mechanical strength, based on the fact that it is much thinner than the composite membranes grown on substrates and it could exhibit good property of gas separation. PMID:24821299

  5. Influence of membrane lipid composition on flavonoid-membrane interactions: Implications on their biological activity.

    PubMed

    Selvaraj, Stalin; Krishnaswamy, Sridharan; Devashya, Venkappayya; Sethuraman, Swaminathan; Krishnan, Uma Maheswari

    2015-04-01

    The membrane interactions and localization of flavonoids play a vital role in altering membrane-mediated cell signaling cascades as well as influence the pharmacological activities such as anti-tumour, anti-microbial and anti-oxidant properties of flavonoids. Various techniques have been used to investigate the membrane interaction of flavonoids. These include partition coefficient, fluorescence anisotropy, differential scanning calorimetry, NMR spectroscopy, electrophysiological methods and molecular dynamics simulations. Each technique will provide specific information about either alteration of membrane fluidity or localization of flavonoids within the lipid bilayer. Apart from the diverse techniques employed, the concentrations of flavonoids and lipid membrane composition employed in various studies reported in literature also are different and together these variables contribute to diverse findings that sometimes contradict each other. This review highlights different techniques employed to investigate the membrane interaction of flavonoids with special emphasis on erythrocyte model membrane systems and their significance in understanding the nature and extent of flavonoid-membrane interactions. We also attempt to correlate the membrane localization and alteration in membrane fluidity with the biological activities of flavonoids such as anti-oxidant, anti-cancer and anti-microbial properties.

  6. Fabrication and characterization of magnetic nanoparticle composite membranes

    NASA Astrophysics Data System (ADS)

    Cruickshank, Akeem Armand

    To effectively and accurately deliver drugs within the human body, both new designs and components for implantable micropumps are being studied. Designs must ensure high biocompatibility, drug compatibility, accuracy and small power consumption. The focus of this thesis was to fabricate a prototype magnetic nanoparticle membrane for eventual incorporation into a biomedical pump and then determine the relationship between this membrane deflection and applied pneumatic or magnetic force. The magnetic nanoparticle polymer composite (MNPC) membranes in this study were composed of crosslinked polydimethylsiloxane (PDMS) and iron oxide nanoparticles (IONPs). An optimal iron oxide fabrication route was identified and particle size in each batch was approximately 24.6 nm. Once these nanoparticles were incorporated into a membrane (5 wt. %), the nanoparticle formed agglomerates with an average diameter of 2.26 +/-1.23 microm. Comparisons between the 0 and 5 wt. % loading of particles into the membranes indicated that the elastic modulus of the composite decreased with increasing particle concentration. The pressure- central deflection of the membranes could not be predicated by prior models and variation between magnetic and pneumatic pressure-deflection curves was quantified. Attempts to fabricate membranes with above 5 wt. % nanoparticles were not successful (no gelation). Fourier Transform Infrared (FTIR) spectroscopy results suggest that excess oleic acid on the nanoparticles prior to mixing might have prevented crosslinking.

  7. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, Suri A.; Pemsler, J. Paul; Cooke, Richard A.; Litchfield, John K.; Smith, Mark B.

    1996-01-01

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates.

  8. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, S.A.; Pemsler, J.P.; Cooke, R.A.; Litchfield, J.K.; Smith, M.B.

    1996-03-05

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates. 2 figs.

  9. NOVEL COMPOSITE MEMBRANES AND PROCESS FOR NATURAL GAS UPGRADING

    SciTech Connect

    Johann LeRoux

    2002-02-01

    The first phase of this project involved the development of a high performance composite membranes for the treatment of natural gas. The objective of the second phase is to demonstrate the commercial potential of a full-size membrane module in a pilot scale field test. This phase is undertaken jointly with our commercial partner, UOP LLC. At the conclusion of Phase I, two composite membrane products had been developed for the enrichment (sweetening) of natural gas. The one was a low pressure membrane with a high CO{sub 2}/CH{sub 4} separation factor that falls within the target range of 25-30 (at 50 C) set for the program. This is a significant improvement over current commercial membranes that have separation factors of around 18-19. The second membrane had excellent high pressure capability and good contamination resistance, with a separation factor of 20-22. Based on the performance and the economic evaluation of the newly developed membranes, and with the input of UOP and DOE, it was decided to devote the demonstration phase of the program to the field testing and commercial evaluation of natural gas dehydration membranes. Due to the events of September 11, the program was also extended by 6 months until June 30, 2002. In Phase II, UOP has essentially completed preparation of the field test site. Site preparation included the re-design of the test system, purchase and installation of analytical equipment, and making the necessary piping and other hardware changes. IMS has produced two commercial sized dehydration membrane modules for the field tests. These have been successfully tested up to pressures expected in the field tests, and the modules have been shipped to the test site. The remainder of the program will comprise performance testing of the membrane modules, evaluation of the results and submission of the final report with recommendations.

  10. Synthesis and performance of antifouling and self-cleaning polyethersulfone/graphene oxide composite membrane functionalized with photoactive semiconductor catalyst.

    PubMed

    Dizge, Nadir; Gonuldas, Hakan; Ozay, Yasin; Ates, Hasan; Ocakoglu, Kasim; Harputlu, Ersan; Yildirimcan, Saadet; Unyayar, Ali

    2017-02-01

    This study was performed to synthesize membranes of polyethersulfone (PES) blended with graphene oxide (GO) and PES blended with GO functionalized with photoactive semiconductor catalyst (TiO2 and ZnO). The antifouling and self-cleaning properties of composite membranes were also investigated. The GO was prepared from natural graphite powder by oxidation method at low temperature. TiO2 and ZnO nanopowders were synthesized by anhydrous sol-gel method. The surface of TiO2 and ZnO nanopowders was modified by a surfactant (myristic acid) to obtain a homogeneously dispersed mixture in a solvent, and then GO was functionalized by loading with these metal oxide nanopowders. The PES membranes blended with GO and functionalized GO into the casting solution were prepared via phase inversion method and tested for their antifouling as well as self-cleaning properties. The composite membranes were synthesized as 14%wt. of PES polymer with three different concentrations (0.5, 1.0, and 2.0%wt.) of GO, GO-TiO2, and GO-ZnO. The functionalization of membranes improved hydrophilicity property of membranes as compared to neat PES membrane. However, the lowest flux was obtained by functionalized membranes with GO-TiO2. The results showed that functionalized membranes demonstrated better self-cleaning property than neat PES membrane. Moreover, the flux recovery rate of functionalized membranes over five cycles was higher than that of neat membrane.

  11. Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.

    PubMed

    Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C

    2015-07-15

    Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.

  12. Composite Metal-hydrogen Electrodes for Metal-Hydrogen Batteries

    SciTech Connect

    Ruckman, M W; Wiesmann, H; Strongin, M; Young, K; Fetcenko, M

    1997-04-01

    The purpose of this project is to develop and conduct a feasibility study of metallic thin films (multilayered and alloy composition) produced by advanced sputtering techniques for use as anodes in Ni-metal hydrogen batteries. The anodes could be incorporated in thin film solid state Ni-metal hydrogen batteries that would be deposited as distinct anode, electrolyte and cathode layers in thin film devices. The materials could also be incorporated in secondary consumer batteries (i.e. type AF(4/3 or 4/5)) which use electrodes in the form of tapes. The project was based on pioneering studies of hydrogen uptake by ultra-thin Pd-capped metal-hydrogen ratios exceeding and fast hydrogen charging and Nb films, these studies suggested that materials with those of commercially available metal hydride materials discharging kinetics could be produced. The project initially concentrated on gas phase and electrochemical studies of Pd-capped niobium films in laboratory-scale NiMH cells. This extended the pioneering work to the wet electrochemical environment of NiMH batteries and exploited advanced synchrotron radiation techniques not available during the earlier work to conduct in-situ studies of such materials during hydrogen charging and discharging. Although batteries with fast charging kinetics and hydrogen-metal ratios approaching unity could be fabricated, it was found that oxidation, cracking and corrosion in aqueous solutions made pure Nb films-and multiiayers poor candidates for battery application. The project emphasis shifted to alloy films based on known elemental materials used for NiMH batteries. Although commercial NiMH anode materials contain many metals, it was found that 0.24 µm thick sputtered Zr-Ni films cycled at least 50 times with charging efficiencies exceeding 95% and [H]/[M] ratios of 0.7-1.0. Multilayered or thicker Zr-Ni films could be candidates for a thin film NiMH battery that may have practical applications as an integrated power source for

  13. Fatigue evaluation of composite-reinforced, integrally stiffened metal panels

    NASA Technical Reports Server (NTRS)

    Dumesnil, C. E.

    1973-01-01

    The fatigue behavior of composite-reinforced, integrally stiffened metal panels was investigated in combined metal and composite materials subjected to fatigue loading. The systems investigated were aluminum-graphite/epoxy, and aluminum-S glass/epoxy. It was found that the composite material would support the total load at limit stress after the metal had completely failed, and the weight of the composite-metal system would be equal to that of an all metal system which would carry the same total load at limit stress.

  14. Evaluation of membrane models and their composition for islet amyloid polypeptide-membrane aggregation.

    PubMed

    Caillon, Lucie; Lequin, Olivier; Khemtémourian, Lucie

    2013-09-01

    Human islet amyloid polypeptide (IAPP) forms amyloid fibrils in the pancreatic islets of patients suffering from type 2 diabetes mellitus (T2DM). The formation of IAPP fibrils has been shown to cause membrane damage which most likely is responsible for the death of pancreatic islet β-cells during the pathogenesis of T2DM. Several studies have demonstrated a clear interaction between IAPP and lipid membranes. However the effect of different lipid compositions and of various membrane mimetics (including micelles, bicelles, SUV and LUV) on fibril formation kinetics and fibril morphology has not yet systematically been analysed. Here we report that the interaction of IAPP with various membrane models promoted different processes of fibril formation. Our data reveal that in SDS and DPC micelles, IAPP adopts a stable α-helical structure for several days, suggesting that the micelle models may stabilize monomeric or small oligomeric species of IAPP. In contrast, zwitterionic DMPC/DHPC bicelles and DOPC SUV accelerate the fibril formation compared to zwitterionic DOPC LUV, indicating that the size of the membrane model and its curvature influence the fibrillation process. Negatively charged membranes decrease the lag-time of the fibril formation kinetics while phosphatidylethanolamine and cholesterol have an opposite effect, probably due to the modulation of the physical properties of the membrane and/or due to direct interactions with IAPP within the membrane core. Finally, our results show that the modulation of lipid composition influences not only the growth of fibrils at the membrane surface but also the interactions of β-sheet oligomers with membranes.

  15. METal matrix composite ANalyzer (METCAN): Theoretical manual

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Chamis, C. C.

    1993-01-01

    This manuscript is intended to be a companion volume to the 'METCAN User's Manual' and the 'METAN Demonstration Manual.' The primary purpose of the manual is to give details pertaining to micromechanics and macromechanics equations of high temperature metal matrix composites that are programmed in the METCAN computer code. The subroutines which contain the programmed equations are also mentioned in order to facilitate any future changes or modifications that the user may intend to incorporate in the code. Assumptions and derivations leading to the micromechanics equations are briefly mentioned.

  16. Metal Matrix Composite Materials for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Jones, C. S. (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) are attractive materials for aerospace applications because of their high specific strength, high specific stiffness, and lower thermal expansion coefficient. They are affordable since complex parts can be produced by low cost casting process. As a result there are many commercial and Department of Defense applications of MMCs today. This seminar will give an overview of MMCs and their state-of-the-art technology assessment. Topics to be covered are types of MMCs, fabrication methods, product forms, applications, and material selection issues for design and manufacture. Some examples of current and future aerospace applications will also be presented and discussed.

  17. Materials analysis by ultrasonics: Metals, ceramics, composites

    NASA Technical Reports Server (NTRS)

    Vary, Alex (Editor)

    1987-01-01

    Research results in analytical ultrasonics for characterizing structural materials from metals and ceramics to composites are presented. General topics covered by the conference included: status and advances in analytical ultrasonics for characterizing material microstructures and mechanical properties; status and prospects for ultrasonic measurements of microdamage, degradation, and underlying morphological factors; status and problems in precision measurements of frequency-dependent velocity and attenuation for materials analysis; procedures and requirements for automated, digital signal acquisition, processing, analysis, and interpretation; incentives for analytical ultrasonics in materials research and materials processing, testing, and inspection; and examples of progress in ultrasonics for interrelating microstructure, mechanical properties, and dynamic response.

  18. Selective Metallization Induced by Laser Activation: Fabricating Metallized Patterns on Polymer via Metal Oxide Composite.

    PubMed

    Zhang, Jihai; Zhou, Tao; Wen, Liang

    2017-02-28

    Recently, metallization on polymer substrates has been given more attention due to its outstanding properties of both plastics and metals. In this study, the metal oxide composite of copper-chromium oxide (CuO·Cr2O3) was incorporated into the polymer matrix to design a good laser direct structuring (LDS) material, and the well-defined copper pattern (thickness =10 μm) was successfully fabricated through selective metallization based on 1064 nm near-infrared pulsed laser activation and electroless copper plating. We also prepared polymer composites incorporated with CuO and Cr2O3; however, these two polymer composites both had very poor capacity of selective metallization, which has no practical value for LDS technology. In our work, the key reasons causing the above results were systematically studied and elucidated using XPS, UV-vis-IR, optical microscopy, SEM, contact angle, ATR FTIR, and so on. The results showed that 54.0% Cu(2+) in the polymer composite of CuO·Cr2O3 (the amount =5 wt %) is reduced to Cu(0) (elemental copper) after laser activation (irradiation); however, this value is only 26.8% for the polymer composite of CuO (the amount =5 wt %). It was confirmed that to achieve a successful selective metallization after laser activation, not only was the new formed Cu(0) (the catalytic seeds) the crucial factor, but the number of generated Cu(0) catalytic seeds was also important. These two factors codetermined the final results of the selective metallization. The CuO·Cr2O3 is very suitable for applications of fabricating metallic patterns (e.g., metal decoration, circuit) on the inherent pure black or bright black polymer materials via LDS technology, which has a prospect of large-scale industrial applications.

  19. Development of Damped Metal Matrix Composites for Advanced Structural Applications

    DTIC Science & Technology

    1990-04-01

    DTIP FiLE COPY Applied Research Laboratory (Dto 00 CD Technical Report NO DEVELOPMENT OF DAMPED METAL MATRIX COMPOSITES FOR ADVANCED STRUCTURAL...DEVELOPMENT OF DAMPED METAL MATRIX COMPOSITES FOR ADVANCED STRUCTURAL APPLICATIONS by Clark A. Updike Ram B. Bhagat Technical Report No. TR 90-004 April 1990... Metal Matrix Composites for Advanced Structural Applications 12 PERSONAL AUTHOR(S) C.A. Updike, R. Bhagat 1 3a TYPE OF REPORT 13b TIME COVERED 14. DATE

  20. 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.

  1. Separation of gases through gas enrichment membrane composites

    DOEpatents

    Swedo, Raymond J.; Kurek, Paul R.

    1988-01-01

    Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

  2. Separation of gases through gas enrichment membrane composites

    DOEpatents

    Swedo, R.J.; Kurek, P.R.

    1988-07-19

    Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

  3. 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.

  4. Economic manufacturing of bulk metallic glass compositions by microalloying

    DOEpatents

    Liu, Chain T.

    2003-05-13

    A method of making a bulk metallic glass composition includes the steps of:a. providing a starting material suitable for making a bulk metallic glass composition, for example, BAM-11; b. adding at least one impurity-mitigating dopant, for example, Pb, Si, B, Sn, P, to the starting material to form a doped starting material; and c. converting the doped starting material to a bulk metallic glass composition so that the impurity-mitigating dopant reacts with impurities in the starting material to neutralize deleterious effects of the impurities on the formation of the bulk metallic glass composition.

  5. Tunable composite membranes for gas separations. Quarterly technical progress report, May--July 1996

    SciTech Connect

    Ferraris, J.P.; Balkus, K.J. Jr.; Musselman, I.H.

    1996-08-05

    Significant progress has been made in the synthesis and characterization of conducting polymer composite membranes for gas separations. Zeolite/polyalkylthiophene composite membranes have been prepared and characterized for zeolite NaY.

  6. Immobilized transition metal-based radical scavengers and their effect on durability of Aquivion® perfluorosulfonic acid membranes

    NASA Astrophysics Data System (ADS)

    D'Urso, C.; Oldani, C.; Baglio, V.; Merlo, L.; Aricò, A. S.

    2016-01-01

    A simple and broadly applicable preparation procedure to obtain silica-supported transition metal (namely Cr, Co and Mn)-based radical scavengers, containing sulfonic acid functionalities, is reported. These systems are widely characterised in terms of structure, bulk and surface composition and morphology by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), X-Ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The scavenger material is loaded in ePTFE reinforced membranes prepared from Aquivion® perfluorosulfonic acid (PFSA) dispersions. All these composite membranes show longer lifetime in Accelerated Stress Tests (AST) and reduced fluoride release in Fenton's tests than the scavenger-free membranes without any loss in electrochemical performance. The Cr-scavenger-based polymer electrolyte shows a three-time larger stability than the pristine membrane.

  7. Separation of macromolecular proteins and rejection of toxic heavy metal ions by PEI/cSMM blend UF membranes.

    PubMed

    Kanagaraj, P; Nagendran, A; Rana, D; Matsuura, T; Neelakandan, S

    2015-01-01

    The charged surface modifying macromolecule (cSMM) was blended into the casting solution of poly(ether imide) (PEI) to prepare surface modified ultrafiltration membranes by phase inversion technique. The separation of proteins including bovine serum albumin, egg albumin, pepsin and trypsin was investigated by the fabricated membranes. On increasing cSMM content, solute rejection decreases whereas membrane flux increases. The pore size and surface porosity of the 5 wt% cSMM blend PEI membranes increases to 41.4 Å and 14.8%, respectively. Similarly, the molecular weight cut-off of the membranes ranged from 20 to 45 kDa, depending on the various compositions of the prepared membranes. The toxic heavy metal ions Cu(II), Cr(III), Zn(II) and Pb(II) from aqueous solutions were subjected to rejection by the prepared blended membrane with various concentration of polyethyleneimine (PETIM) as water soluble polymeric ligand. It was found that the rejection behavior of metal ion depends on the PETIM concentration and the stability complexation of metal ion with ligand.

  8. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.

    1995-05-01

    Ceramic-metal composites are being developed because their high stiffness-to weight ratios, good fracture toughness, and variable electrical and thermal properties give them advantages over more conventional materials. However, because ceramic-metal composite components presently are more expensive than monolithic materials, improvements in processing are required to reduce manufacturing costs. Reactive metal penetration is a promising new method for making ceramic- and metal-matrix composites that has the advantage of being inherently a net-shape process. This technique, once fully developed, will provide another capability for manufacturing the advanced ceramic composites that are needed for many light-weight structural and wear applications. The lower densities of these composites lead directly to energy savings in use. Near-net-shape fabrication of composite parts should lead to additional savings because costly and energy intensive grinding and machining operations are significantly reduced, and the waste generated from such finishing operations is minimized. The goals of this research program are: (1) to identify feasible compositional systems for making composites by reactive metal penetration; (2) to understand the mechanism(s) of composite formation by reactive metal penetration; and (3) to learn how to control and optimize reactive metal penetration for economical production of composites and composite coatings.

  9. Metallic glass nanostructures of tunable shape and composition.

    PubMed

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J; Schroers, Jan

    2015-04-22

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top-down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties.

  10. Metal Matrix Composites for Rocket Engine Applications

    NASA Technical Reports Server (NTRS)

    McDonald, Kathleen R.; Wooten, John R.

    2000-01-01

    This document is from a presentation about the applications of Metal Matrix Composites (MMC) in rocket engines. Both NASA and the Air Force have goals which would reduce the costs and the weight of launching spacecraft. Charts show the engine weight distribution for both reuseable and expendable engine components. The presentation reviews the operating requirements for several components of the rocket engines. The next slide reviews the potential benefits of MMCs in general and in use as materials for Advanced Pressure Casting. The next slide reviews the drawbacks of MMCs. The reusable turbopump housing is selected to review for potential MMC application. The presentation reviews solutions for reusable turbopump materials, pointing out some of the issues. It also reviews the development of some of the materials.

  11. Composite lightweight non-metallic vehicle frame

    SciTech Connect

    Pabst, R.D.

    1986-03-04

    A non-metallic ladder type automotive frame is described having beam elements formed of composite plastic materials. The frame consists of: paired opposed elongate lateral beams interconnected by plural cross beams, each of the beams and cross beams having, a rigid lower density core formed by foaming plastic material in a peripheral mold to create a structure having closed cells and a graduated density that is greatest at the periphery of the core, and a higher density peripheral skin formed of polymeric matrix material adhered to the core and embedding reinforcing fiber in the form of woven cloth, plural layers of the cloth, covering the peripheral surfaces of the beams and additional layers of the cloth covering top and bottom portions of the beams, and means of releasably fastening automotive components to at least some of the beams.

  12. Polyamino acid functionalized membranes for metal capture and nanofiltration of organics: Modeling and experimental verification

    NASA Astrophysics Data System (ADS)

    Hestekin, Jamie Allen

    2000-10-01

    Passive membranes have been used for separations ranging from seawater desalination via reverse osmosis to the separation of particles with microfiltration membranes. However the attachment of macromolecules, with multiple functional sites, to microfiltration membranes allows for more selective separations. For these reasons, we have designed a novel membrane system, consisting of cellulose-based microfiltration membranes functionalized with polyamino acids (2,500--15,000 MW). Because of the high carboxyl content of the polyamino acids, these membranes have been shown to be extremely useful for the separation of heavy metals from aqueous solutions. The primary objective of this research was to establish the sorption mechanisms of functionalized microfiltration membranes and use these mechanisms to predict the rate behavior of metal transport through these membranes. Both cellulose acetate and pure cellulose were used as membrane support materials. Extensive experiments (pH 3--6) were conducted (under convective flow mode) with the derivatized membranes involving the heavy metals: lead, cadmium, nickel, copper, and selected mixtures with calcium in aqueous solutions. Metal sorption results were found to be a function of derivatization (aldehydes) density of membranes and degree of attachment of the polyfunctional groups, number of functional groups per chain, membrane surface area, and the type of metals to be sorbed. We have obtained metal sorption capacities as high as 1.5 g metal/g membrane. As opposed to homogeneous solution systems, the molar sorption capacities of the functional carboxyl sites are significantly enhanced in the membrane pores because of counterion condensation resulting partly from the extremely high charge densities in the membrane pores. This phenomenon was incorporated in a kinetic model for the prediction of sorption behavior. The model studied the effect of pore size, polyamino acid attachment density, pH, and metal type. Finally, in

  13. 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.

  14. 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.

  15. Solid polymer electrolyte composite membrane comprising plasma etched porous support

    DOEpatents

    Liu, Han; LaConti, Anthony B.

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  16. The effect of solid metal composition on solid metal/ liquid metal partitioning of trace elements

    NASA Astrophysics Data System (ADS)

    Rai, N.; van Westrenen, W.

    2010-12-01

    Fundamental understanding of the partitioning behaviour of elements between different core and/or mantle phases is needed to constrain processes of planetary differentiation and evolution. The partitioning behaviour of elements between solid metal and liquid metal in the Fe-S system, of relevance to core crystallisation in planetesimals and the terrestrial planets, has been investigated by several workers [1-6], most of whom [1-5] conclude that variations in partition coefficients can be explained by variations in melt composition. However, recently Stewart et al. [6] showed that the crystal-lattice strain model commonly used to describe silicate mineral - silicate melt partitioning can be applied to partially molten metallic systems. This suggests the structure of the solid metal also plays a role in determining solid metal / molten metal partitioning. Here, we investigate the effect of the structure of the solid metal in the Fe-S system on solid/liquid metal partitioning by obtaining new element partitioning data at pressures between 0.5 and 3 GPa. The effect of the solid metal is isolated from pressure-temperature-melt composition effects by performing experiments at constant P and T with two Fe-S bulk compositions on either side of the eutectic composition. In addition to the effect of solid metal composition we investigate the effects of pressure and S content on trace element partitioning behaviour and the application of the lattice strain model to our results. Starting mixtures were doped with several hundred ppm levels of trace elements Ni, Co, W, Mo, V, Nb, Ta, Sn, Cu, Pb, Zn, Cr, Mn, P, Ge,. Experiments were performed using a QUICKPress piston cylinder apparatus at the VU University, Amsterdam using alumina capsules. Experiments were heated to 1073 K at pressure and allowed to sinter for a duration of 10 hours before the temperature was raised at a rate of 50 K / min to the target value. Preliminary EPMA data for a 1 GPa experiment with FeS as the solid

  17. Inelastic deformation of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Lissenden, C. J.; Herakovich, C. T.; Pindera, M-J.

    1993-01-01

    A theoretical model capable of predicting the thermomechanical response of continuously reinforced metal matrix composite laminates subjected to multiaxial loading was developed. A micromechanical model is used in conjunction with nonlinear lamination theory to determine inelastic laminae response. Matrix viscoplasticity, residual stresses, and damage to the fiber/matrix interfacial zone are explicitly included in the model. The representative cell of the micromechanical model is considered to be in a state of generalized plane strain, enabling a quasi two-dimensional analysis to be performed. Constant strain finite elements are formulated with elastic-viscoplastic constitutive equations. Interfacial debonding is incorporated into the model through interface elements based on the interfacial debonding theory originally presented by Needleman, and modified by Tvergaard. Nonlinear interfacial constitutive equations relate interfacial tractions to displacement discontinuities at the interface. Theoretical predictions are compared with the results of an experimental program conducted on silicon carbide/titanium (SiC/Ti) unidirectional, (O4), and angle-ply, (+34)(sub s), tubular specimens. Multiaxial loading included increments of axial tension, compression, torque, and internal pressure. Loadings were chosen in an effort to distinguish inelastic deformation due to damage from matrix plasticity and separate time-dependent effects from time-independent effects. Results show that fiber/matrix debonding is nonuniform throughout the composite and is a major factor in the effective response. Also, significant creep behavior occurs at relatively low applied stress levels at room temperature.

  18. Stabilization of composition fluctuations in mixed membranes by hybrid lipids

    NASA Astrophysics Data System (ADS)

    Safran, Samuel; Palmieri, Benoit

    2013-03-01

    A ternary mixture model is proposed to describe composition fluctuations in mixed membranes composed of saturated, unsaturated and hybrid lipids. The asymmetric hybrid lipid has one saturated and one unsaturated hydrocarbon chain and it can reduce the packing incompatibility between saturated and unsaturated lipids. A methodology to recast the free-energy of the lattice in terms of a continuous isotropic field theory is proposed and used to analyze composition fluctuations above the critical temperature. The effect of hybrid lipids on fluctuations domains rich in saturated/unsaturated lipids is predicted. The correlation length of such fluctuations decreases significantly with increasing amounts of hybrids even if the temperature is maintained close to the critical temperature. This provides an upper bound for the domain sizes expected in rafts stabilized by hybrids, above the critical temperature. When the hybrid composition of the membrane is increased further, a crossover value is found above which ``stripe-like'' fluctuations are observed. The wavelength of these fluctuations decreases with increasing hybrid fraction and tends toward a molecular size in a membrane that contains only hybrids.

  19. Membrane deformation controlled by monolayer composition of embedded amphiphilic nanoparticles

    NASA Astrophysics Data System (ADS)

    van Lehn, Reid; Alexander-Katz, Alfredo

    2014-03-01

    In recent work, we have shown that charged, amphiphilic nanoparticles (NPs) can spontaneously insert into lipid bilayers, embedding the NP in a conformation resembling a transmembrane protein. Many embedded membrane proteins exert an influence on surrounding lipids that lead to deformation and membrane-mediated interactions that may be essential for function. Similarly, embedded NPs will also induce membrane deformations related to the same physicochemical forces. Unlike many transmembrane proteins, however, the highly charged NPs may exert preferential interactions on surrounding lipid head groups. In this work, we use atomistic molecular dynamics simulations to show that the membrane around embedded particles may experience local thinning, head group reorientation, and an increase in lipid density depending on the size and surface composition of the NP. We quantify the extent of these deformations and illustrate the complex interplay between lipid tail group and head group interactions that go beyond pure thickness deformations that may be expected from coarse-grained or continuum models. This work thus suggests guidelines for the design of particles that spontaneously partition into lipid bilayers and influence local membrane mechanical properties in a targeted manner.

  20. Porous anisotropic metal nanostructures through controlled transmetallation across a dialysis membrane.

    PubMed

    Shukla, Sourabh; Pasricha, Renu; Sastry, Murali

    2009-11-01

    Nanostructured metals with hollow interiors are of technological importance due to their unique optoelectronic properties and enhanced surface area. We describe herein, a novel method for the synthesis of anisotropic gold and palladium nanoparticles through a simple galvanic replacement reaction across a semi-permeable dialysis membrane. The control over the reaction kinetics achieved by the presence of membrane enables one to tune the bimetal composition, particle porosity and morphology. Rapid outward diffusion of silver ions generated from the sacrificial silver nanoparticles even at room temperatures prevents the precipitation of high quantities of silver chloride, thereby circumventing the need for product purification. The porous anisotropic nanostructures have potential applications in catalysis, cell imaging and therapeutics.

  1. Composite membrane of niobium(V) oxide and cellulose acetate: Preparation and characterization

    SciTech Connect

    Campos, E.A.; Gushikem, Y.

    1997-09-01

    Composite membranes of niobium(V) oxide and cellulose acetate (Cel/Nb{sub 2}O{sub 5}) were prepared with the following Nb{sub 2}O{sub 5} loadings (in wt%): 1.1, 6.1, 9.8, 15.6, and 20.9. The thermal stability of the membranes slightly decreased in relation to the pure membrane on incorporation of the metal oxide into the matrix. Scanning electron microscopy and niobium mapping with an X-ray EDS microprobe showed that the metal oxide particles are homogeneously dispersed in the matrix. The electronic absorption bands indicated that the oxide particle size varies from that of the monomer to those of oligomer species on increased Nb{sub 2}O{sub 5} loading in the matrix. The dispersed oxide possesses mainly Lewis acid character, a clear indication that on increasing the oxide loading in the matrix, the coordination number of the metal is not saturated by formation of the Nb-O-Nb bond. These materials can be useful in ion-exchange process, as supports for enzymes, in catalytic reactions, and in reverse osmosis experiments.

  2. A typical flat-panel membrane bioreactor with a composite membrane for sulfur removal

    NASA Astrophysics Data System (ADS)

    Guan, Jian; Xiao, Yuan; Song, Jimin; Miao, Junhe

    2014-03-01

    The aim of this work was to provide a concrete study to understand the effects of operation on biofilm morphology and microstructure and degradation efficiency for the disposal of sulfur dioxide produced by coal-fired power plants. For this purpose, a flat-panel reactor-membrane bioreactor (MBR) with a composite membrane consisting of a dense layer and a support layer was designed; the membrane bioreactors inoculated with Thiobacillus ferrooxidans were further conducted for the removal of sulfur dioxide. Dry weight, active biomass, pressure drop, removal efficiency, morphology and structure of the formed biofilms were investigated and analyzed over period of biofilm formation. The results found that the dry weight, biomass, pressure drops and removal efficiency increased rapidly during biofilm formation, remained relatively stable in the stabilization period of biofilm growth, and finally reached 0.085 g, 7.00 μg, 180 Pa, and 78%, respectively. Our results suggested the MBR is available for flue-gas desulfurization.

  3. Compositional Heterogeneity in Ternary Models for the Cell Membrane

    NASA Astrophysics Data System (ADS)

    Smith, Robin; Heberle, Frederick; Wu, Jing; Feigenson, Gerald

    2010-03-01

    Ternary models for the cell membrane comprised of cholesterol (Chol) plus high and low melting temperature lipids exhibit rich phase behavior as a function of temperature and composition. Of particular interest is a region of coexisting disordered and ordered fluid phases that is thought to indicate how lipids organize to promote protein function in the cell membrane. We have used fluorescence resonance energy transfer to investigate the ternary mixtures DOPC(1,2-dioleoyl-sn-glycero-3-phosphocholine)/bSM (porcine brainsphingomyelin)/Chol and POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine)/bSM/Chol at high compositional resolution. We confirmed liquid coexistence for DOPC/bSM/Chol at 15 and 25C that melts by 35C, but in contrast to previous studies we detected no fluid-phase compositional heterogeneity for POPC/bSM/Chol from 5-35C. If domains exist, they must be smaller than the approximately 5 nm sensitivity provided by the fluorescent lipid analogs employed. We propose electron spin resonance and x-ray scattering for measuring whether liquid-phase compositional heterogeneity occurs for POPC/bSM/Chol. Understanding POPC/bSM/Chol phase behavior will provide a framework for investigating peptide/lipid interactions in a biologically relevant lipid mixture.

  4. Arc spray fabrication of metal matrix composite monotape

    NASA Technical Reports Server (NTRS)

    Westfall, L. J. (Inventor)

    1985-01-01

    Arc metal spraying is used to spray liquid metal onto an array of high strength fibers that were previously wound onto a large drum contained inside a controlled atmosphere chamber. This chamber is first evacuated to remove gaseous contaminants and then backfilled with a neutral gas up to atmospheric pressure. This process is used to produce a large size metal matrix composite monotape.

  5. Amorphous Metals and Composites as Mirrors and Mirror Assemblies

    NASA Technical Reports Server (NTRS)

    Hofmann, Douglas C. (Inventor); Davis, Gregory L. (Inventor); Agnes, Gregory S. (Inventor); Shapiro, Andrew A. (Inventor)

    2016-01-01

    A mirror or mirror assembly fabricated by molding, pressing, assembling, or depositing one or more bulk metal glass (BMG), bulk metal glass composite (BMGMC), or amorphous metal (AM) parts and where the optical surface and backing of the mirror can be fabricated without machining or polishing by utilizing the unique molding capabilities of this class of materials.

  6. Metallized Nanotube Polymer Composite (MNPC) and Methods for Making Same

    NASA Technical Reports Server (NTRS)

    Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Nazem, Negin (Inventor); Taylor, Larry (Inventor); Kang, Jin Ho (Inventor); Kim, Jae-Woo (Inventor); Sauti, Godfrey (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2017-01-01

    A novel method to develop highly conductive functional materials which can effectively shield various electromagnetic effects (EMEs) and harmful radiations. Metallized nanotube polymer composites (MNPC) are composed of a lightweight polymer matrix, superstrong nanotubes (NT), and functional nanoparticle inclusions. MNPC is prepared by supercritical fluid infusion of various metal precursors (Au, Pt, Fe, and Ni salts), incorporated simultaneously or sequentially, into a solid NT-polymer composite followed by thermal reduction. The infused metal precursor tends to diffuse toward the nanotube surface preferentially as well as the surfaces of the NT-polymer matrix, and is reduced to form nanometer-scale metal particles or metal coatings. The conductivity of the MNPC increases with the metallization, which provides better shielding capabilities against various EMEs and radiations by reflecting and absorbing EM waves more efficiently. Furthermore, the supercritical fluid infusion process aids to improve the toughness of the composite films significantly regardless of the existence of metal.

  7. New extensions in the development of deformation processed metal-metal matrix composites

    SciTech Connect

    Ellis, T.W.; Gibson, E.D.

    1993-10-01

    Copper-Refractory metal composites have been under development for some time. The experience gained with these materials has been used as a starting point for investigations into other alloy systems. Deformation processing for the production of metal-metal matrix composites has been applied to titanium-yttrium, yttrium-niobium, copper-cobalt, aluminum-niobium and magnesium-refractory metal alloys. This process has been used to produce elevated strength material and also for the production of electrical capacitors.

  8. Control of porosity and pore size of metal reinforced carbon nanotube membranes.

    PubMed

    Dumee, Ludovic; Velleman, Leonora; Sears, Kallista; Hill, Matthew; Schutz, Jurg; Finn, Niall; Duke, Mikel; Gray, Stephen

    2010-12-21

    Membranes are crucial in modern industry and both new technologies and materials need to be designed to achieve higher selectivity and performance. Exotic materials such as nanoparticles offer promising perspectives, and combining both their very high specific surface area and the possibility to incorporate them into macrostructures have already shown to substantially increase the membrane performance. In this paper we report on the fabrication and engineering of metal-reinforced carbon nanotube (CNT) Bucky-Paper (BP) composites with tuneable porosity and surface pore size. A BP is an entangled mesh non-woven like structure of nanotubes. Pure CNT BPs present both very high porosity (>90%) and specific surface area (>400 m2/g). Furthermore, their pore size is generally between 20-50 nm making them promising candidates for various membrane and separation applications. Both electro-plating and electroless plating techniques were used to plate different series of BPs and offered various degrees of success. Here we will report mainly on electroless plated gold/CNT composites. The benefit of this method resides in the versatility of the plating and the opportunity to tune both average pore size and porosity of the structure with a high degree of reproducibility. The CNT BPs were first oxidized by short UV/O3 treatment, followed by successive immersion in different plating solutions. The morphology and properties of these samples has been investigated and their performance in air permeation and gas adsorption will be reported.

  9. Control of Porosity and Pore Size of Metal Reinforced Carbon Nanotube Membranes

    PubMed Central

    Dumee, Ludovic; Velleman, Leonora; Sears, Kallista; Hill, Matthew; Schutz, Jurg; Finn, Niall; Duke, Mikel; Gray, Stephen

    2011-01-01

    Membranes are crucial in modern industry and both new technologies and materials need to be designed to achieve higher selectivity and performance. Exotic materials such as nanoparticles offer promising perspectives, and combining both their very high specific surface area and the possibility to incorporate them into macrostructures have already shown to substantially increase the membrane performance. In this paper we report on the fabrication and engineering of metal-reinforced carbon nanotube (CNT) Bucky-Paper (BP) composites with tuneable porosity and surface pore size. A BP is an entangled mesh non-woven like structure of nanotubes. Pure CNT BPs present both very high porosity (>90%) and specific surface area (>400 m2/g). Furthermore, their pore size is generally between 20–50 nm making them promising candidates for various membrane and separation applications. Both electro-plating and electroless plating techniques were used to plate different series of BPs and offered various degrees of success. Here we will report mainly on electroless plated gold/CNT composites. The benefit of this method resides in the versatility of the plating and the opportunity to tune both average pore size and porosity of the structure with a high degree of reproducibility. The CNT BPs were first oxidized by short UV/O3 treatment, followed by successive immersion in different plating solutions. The morphology and properties of these samples has been investigated and their performance in air permeation and gas adsorption will be reported. PMID:24957493

  10. Characteristics of ionic polymer-metal composite with chemically doped TiO2 particles

    NASA Astrophysics Data System (ADS)

    Jung, Youngsoo; Kim, Seong Jun; Kim, Kwang J.; Lee, Deuk Yong

    2011-12-01

    Many studies have investigated techniques to improve the bending performance of ionic polymer-metal composite (IPMC) actuators, including 'doping' of metal particles in the polymer membrane usually by means of physical processes. This study is mainly focused on the characterization of the physical, electrochemical and electromechanical properties of TiO2-doped ionic polymer membranes and IPMCs prepared by the sol-gel method, which results in a uniform distribution of the particles inside the polymer membrane. X-ray and UV-visible spectra indicate the presence of anatase-TiO2 in the modified membranes. TiO2-doped membranes (0.16 wt%) exhibit the highest level of water uptake. The glass transition temperature of these membranes, measured using differential scanning calorimetry (DSC), increases with the increase of the amount of TiO2 in the membrane. Dynamic mechanical analysis (DMA) demonstrated that the storage modulus of dried TiO2-doped ionic polymer membranes increases as the amount of TiO2 in the membrane increases, whereas the storage modulus of hydrated samples is closely related to the level of water uptake. Electrochemical impedance spectroscopy (EIS) shows that the conductivity of TiO2-doped membranes decreases with increasing TiO2 content in spite of an internal resistance drop in the samples. Above all, bending deflection of TiO2-doped IPMC decreased with higher TiO2 content in the membrane while the blocking force of each sample increased with the higher TiO2 content. Additionally, it was determined that the lifetime of IPMC is strongly dependent on the level of water uptake.

  11. Evaluation of waterjet-machined metal matrix composite tensile specimens

    SciTech Connect

    Lavender, C.A.; Smith, M.T.

    1986-04-01

    Four magnesium/boron carbide metal matrix composite (MMC) tensile specimens fabricated using the waterjet machining method were evaluated in order to determine the effects of the waterjet material removal process on the composite material surface structure and properties. These results were then compared with data from material conventionally machined. Results showed that while waterjet cutting produces a rough surface finish and does not meet specified dimensional tolerances, the technique appears to be suitable for sectioning and rough machining of metal matrix composites.

  12. Aqueous alternatives for metal and composite cleaning

    NASA Technical Reports Server (NTRS)

    Quitmeyer, Joann

    1994-01-01

    For many years the metalworking industry has cleaned metal and composite substrates with chlorinated solvents. Recently, however, health and disposal related environmental concerns have increased regarding chlorinated solvents, including 1,1,1-trichloroethane, trichloroethylene, methylene chloride, or Freon'. World leaders have instituted a production ban of certain ozone depleting chlorofluorocarbons (CFC's) by 1996. The Occupational Safety and Health Administration (OSHA) has instituted worker vapor exposure limitations for virtually all of the solvents used in solvent-based cleaners. In addition, the United States Environmental Protection Agency (EPA) has defined nearly all solvent-based cleaners as 'hazardous'. Cradle to grave waste responsibility is another reason manufacturers are trying to replace chlorinated solvents in their cleaning processes. Because of these factors, there now is a world wide effort to reduce and/or eliminate the use of chlorinated solvents for industrial cleaning. Waterbased cleaners are among the alternatives being offered to the industry. New technology alkaline cleaners are now available that can be used instead of chlorinated solvents in many cleaning processes. These waterbased cleaners reduce the release of volatile organic compounds (VOC's) by as much as 99 percent. (The definition and method of calculation of VOC's now varies from region to region.) Hazardous waste generation can also be significantly reduced or eliminated with new aqueous technology. This in turn can ease worker exposure restrictions and positively impact the environment. This paper compares the chemical and physical properties of this aqueous cleaners versus chlorinated solvents.

  13. Robust control of ionic polymer metal composites

    NASA Astrophysics Data System (ADS)

    Kang, Sunhyuk; Shin, Jongho; Kim, Seong Jun; Kim, H. Jin; Hyup Kim, Yong

    2007-12-01

    Ionic polymer-metal composites (IPMCs) have been considered for various applications due to their light weight, large bending, and low actuation voltage requirements. However, their response can be slow and vary widely, depending on various factors such as fabrication processes, water content, and contact conditions with the electrodes. In order to utilize their capability in various high-performance microelectromechanical systems, controllers need to address this uncertainty and non-repeatability while improving the response speed. In this work, we identified an empirical model for the dynamic relationship between the applied voltage and the IPMC beam deflection, which includes the uncertainties and variations of the response. Then, four types of controller were designed, and their performances were compared: a proportional-integral-derivative (PID) controller with optimized gains using a co-evolutionary algorithm, and three types of robust controller based on H_\\infty , H_\\infty with loop shaping, and μ-synthesis, respectively. Our results show that the robust control techniques can significantly improve the IPMC performance against non-repeatability or parametric uncertainties, in terms of the faster response and lower overshoot than the PID control, using lower actuation voltage.

  14. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.

    1997-04-01

    Achieving better performance in commercial products and processes often is dependent on availability of new and improved materials. Ceramic-metal composites have advantages over more conventional materials because of their high stiffness-to-weight ratios, good fracture toughness, and because their electrical and thermal properties can be varied through control of their compositions and microstructures. However, ceramic composites will be more widely used only when their costs are competitive with other materials and when designers have more confidence in their reliability. Over the past four years reactive metal penetration has been shown to be a promising technique for making ceramic and metal-matrix composites to near-net-shape with control of both composition and microstructure. It appears that, with sufficient development, reactive metal penetration could be an economical process for manufacturing many of the advanced ceramic composites that are needed for light-weight structural and wear applications for transportation and energy conversion devices. Near-net-shape fabrication of parts is a significant advantage because costly and energy intensive grinding and machining operations are substantially reduced, and the waste generated from such finishing operations is minimized. The most promising compositions to date consist of Al and Al{sub 2}O{sub 3}; thus, these composites should be of particular interest to the aluminum industry. The goals of this ceramic-metal composite research and development program are: (1) to identify compositions favorable for making composites by reactive metal penetration; (2) to understand the mechanism(s) by which these composites are formed; (3) to control and optimize the process so that composites and composite coatings can be made economically; and (4) to apply R&D results to problems of interest to the aluminum industry.

  15. Sorting of amphiphile membrane components in curvature and composition gradients

    NASA Astrophysics Data System (ADS)

    Tian, Aiwei

    Phase and shape heterogeneities in biomembranes are of functional importance. However, it is difficult to elucidate the roles membrane heterogeneities play in maintaining cellular function due to the complexity of biomembranes. Therefore, investigations of phase behavior and composition/curvature coupling in lipid and polymer model membranes offer some advantages. In this thesis, phase properties in lipid and polymer giant vesicles were studied. Line tension at the fluid/fluid phase boundary of giant lipid unilamellar vesicles was determined directly by micropipette aspiration, and found to be composition-dependent. Dynamics of calcium-induced domains within polyanionic vesicles subject to chemical stimuli were investigated, which revealed the strength of molecular interaction and suggested applications in triggered delivery. In addition, curvature sorting of lipids and proteins was examined. Lipid membrane tethers were pulled from giant unilamellar vesicles using two micropipettes and a bead. Tether radius can be controlled and measured in this system. By examining fluorescence intensity of labeled molecules as a function of curvature, we found that DiI dyes (lipid analogues with spontaneous curvatures) had no curvature preference down to radii of 10 nm. Theoretical calculation predicted that the distribution of small lipids was dominated by entropy instead of bending energy. However protein Cholera toxin subunit B was efficiently sorted away from the high positive curvature due to its negative spontaneous curvature. Bending stiffness was determined to decrease as curvature increased in homogeneous membranes with ternary lipid mixtures near a critical consulate point, revealing the strong preferential intermolecular interactions of such mixtures. In addition, diffusion controlled domain growth was observed in tethers pulled from phase-separated vesicles, which provides a new dynamic sorting principle for lipids and proteins in curvature gradients.

  16. Membrane Composition Variation and Underdamped Mechanics near Transmembrane Proteins and Coats

    NASA Astrophysics Data System (ADS)

    Rautu, S. Alex; Rowlands, George; Turner, Matthew S.

    2015-03-01

    We study the effect of transmembrane proteins on the shape, composition, and thermodynamic stability of the surrounding membrane. When the coupling between membrane composition and curvature is strong enough, the nearby membrane composition and shape both undergo a transition from overdamped to underdamped spatial variation, well before the membrane becomes unstable in the bulk. This transition is associated with a change in the sign of the thermodynamic energy and, hence, favors the early stages of coat assembly necessary for vesiculation (budding) and may suppress the activity of mechanosensitive membrane channels and transporters. Our results suggest an approach to obtain physical parameters of the membrane that are otherwise difficult to measure.

  17. A facile TiO2/PVDF composite membrane synthesis and their application in water purification

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zhang, Yiming; Fan, Rong; Lewis, Rosmala

    2016-01-01

    In this work, we have demonstrated a facile wet chemical method to synthesise TiO2/PVDF composite membranes as alternative water purification method to traditional polymer-based membrane. For the first time, hydrothermally grown TiO2 nanofibers under alkali conditions were successfully inserted into PVDF membranes matrix. The structure, permeability and anti-fouling performance of as-prepared PVDF/TiO2 composite membranes were studied systematically. The TiO2/PVDF composite membranes prepared in this work promise great potential uses in water purification applications as microfiltration membranes due to its excellent physical/chemical resistance, anti-fouling and mechanical properties.

  18. Method of making metal matrix composites reinforced with ceramic particulates

    DOEpatents

    Cornie, James A.; Kattamis, Theodoulos; Chambers, Brent V.; Bond, Bruce E.; Varela, Raul H.

    1989-01-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys.

  19. Method of making metal matrix composites reinforced with ceramic particulates

    DOEpatents

    Cornie, J.A.; Kattamis, T.; Chambers, B.V.; Bond, B.E.; Varela, R.H.

    1989-08-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys. 2 figs.

  20. NOVEL COMPOSITE MEMBRANES FOR HYDROGEN SEPARATION IN GASIFICATION PROCESSES IN VISION 21 ENERGY PLANTS

    SciTech Connect

    Michael Schwartz

    2003-07-01

    ITN Energy Systems, along with its team members, the Idaho National Engineering and Environmental Laboratory, Nexant Consulting, Argonne National Laboratory and Praxair, propose to develop a novel composite membrane structure for hydrogen separation as a key technology module within the future ''Vision 21'' fossil fuel plants. The ITN team is taking a novel approach to hydrogen separation membrane technology where fundamental engineering material development is fully integrated into fabrication designs; combining functionally graded materials, monolithic module concept and plasma spray manufacturing techniques. The technology is based on the use of Ion Conducting Ceramic Membranes (ICCM) for the selective transport of hydrogen. The membranes are comprised of composites consisting of a proton conducting ceramic and a second metallic phase to promote electrical conductivity. Functional grading of the membrane components allows the fabrication of individual membrane layers of different materials, microstructures and functions directly into a monolithic module. Plasma spray techniques, common in industrial manufacturing, are well suited for fabricating ICCM hydrogen separation modules inexpensively, yielding compact membrane modules that are amenable to large scale, continuous manufacturing with low costs. This program will develop and evaluate composite membranes and catalysts for hydrogen separation. Components of the monolithic modules will be fabricated by plasma spray processing. The engineering and economic characteristics of the proposed ICCM approach, including system integration issues, will also be assessed. This will result in a complete evaluation of the technical and economic feasibility of ICCM hydrogen separation for implementation within the ''Vision 21'' fossil fuel plant. The ICCM hydrogen separation technology is targeted for use within the gasification module of the ''Vision 21'' fossil fuel plant. The high performance and low-cost manufacturing of

  1. NOVEL COMPOSITE MEMBRANES FOR HYDROGEN SEPARATION IN GASIFICATION PROCESSES IN VISION 21 ENERGY PLANTS

    SciTech Connect

    Michael Schwartz

    2003-10-01

    ITN Energy Systems, along with its team members, the Idaho National Engineering and Environmental Laboratory, Nexant Consulting, Argonne National Laboratory and Praxair, propose to develop a novel composite membrane structure for hydrogen separation as a key technology module within the future ''Vision 21'' fossil fuel plants. The ITN team is taking a novel approach to hydrogen separation membrane technology where fundamental engineering material development is fully integrated into fabrication designs; combining functionally graded materials, monolithic module concept and plasma spray manufacturing techniques. The technology is based on the use of Ion Conducting Ceramic Membranes (ICCM) for the selective transport of hydrogen. The membranes are comprised of composites consisting of a proton conducting ceramic and a second metallic phase to promote electrical conductivity. Functional grading of the membrane components allows the fabrication of individual membrane layers of different materials, microstructures and functions directly into a monolithic module. Plasma spray techniques, common in industrial manufacturing, are well suited for fabricating ICCM hydrogen separation modules inexpensively, yielding compact membrane modules that are amenable to large scale, continuous manufacturing with low costs. This program will develop and evaluate composite membranes and catalysts for hydrogen separation. Components of the monolithic modules will be fabricated by plasma spray processing. The engineering and economic characteristics of the proposed ICCM approach, including system integration issues, will also be assessed. This will result in a complete evaluation of the technical and economic feasibility of ICCM hydrogen separation for implementation within the ''Vision 21'' fossil fuel plant. The ICCM hydrogen separation technology is targeted for use within the gasification module of the ''Vision 21'' fossil fuel plant. The high performance and low-cost manufacturing of

  2. High Temperature Self-Healing Metallic Composite

    NASA Astrophysics Data System (ADS)

    Kutelia, E. R.; Bakhtiyarov, S. I.; Tsurtsumia, O. O.; Bakhtiyarov, A. S.; Eristavi, B.

    2012-01-01

    This work presents the possibility to realize the self healing mechanisms for heterogeneous architectural metal/ceramic high temperature sandwich thermal barrier coating systems on the surfaces refractory metals by analogy of wound healing in the skin.

  3. Preparation of Sulfonated Poly(aryl ether sulfone) Electrospun Mat/Phosphosilicate Composite Proton Exchange Membrane

    NASA Astrophysics Data System (ADS)

    Wang, Limei; Dou, Liyan; Guan, Guoying

    2017-03-01

    Side-chain-type sulfonated poly(aryl ether sulfone) (SPES) was synthesized and then electrospun into mats. Phosphosilicate glass (PS) via in situ sol-gel synthesis was enclosed in the mats to form a new reinforced composite membrane. The SPES/PS composite membranes showed satisfactory dimensional change behavior with varying humidity. Especially, the composite membrane exhibits excellent proton conductivity at harsh measurement conditions of low humidity at 80°C. The composite membrane with outstanding combined properties has potential applications for high temperature polymer electrolyte membrane fuel cells.

  4. Preparation of Sulfonated Poly(aryl ether sulfone) Electrospun Mat/Phosphosilicate Composite Proton Exchange Membrane

    NASA Astrophysics Data System (ADS)

    Wang, Limei; Dou, Liyan; Guan, Guoying

    2017-01-01

    Side-chain-type sulfonated poly(aryl ether sulfone) (SPES) was synthesized and then electrospun into mats. Phosphosilicate glass (PS) via in situ sol-gel synthesis was enclosed in the mats to form a new reinforced composite membrane. The SPES/PS composite membranes showed satisfactory dimensional change behavior with varying humidity. Especially, the composite membrane exhibits excellent proton conductivity at harsh measurement conditions of low humidity at 80°C. The composite membrane with outstanding combined properties has potential applications for high temperature polymer electrolyte membrane fuel cells.

  5. Simplified process for leaching precious metals from fuel cell membrane electrode assemblies

    DOEpatents

    Shore, Lawrence; Matlin, Ramail

    2009-12-22

    The membrane electrode assemblies of fuel cells are recycled to recover the catalyst precious metals from the assemblies. The assemblies are cryogenically embrittled and pulverized to form a powder. The pulverized assemblies are then mixed with a surfactant to form a paste which is contacted with an acid solution to leach precious metals from the pulverized membranes.

  6. Electrospun Superhydrophobic Organic/Inorganic Composite Nanofibrous Membranes for Membrane Distillation.

    PubMed

    Li, Xiong; Yu, Xufeng; Cheng, Cheng; Deng, Li; Wang, Min; Wang, Xuefen

    2015-10-07

    Electrospun superhydrophobic organic/inorganic composite nanofibrous membranes exhibiting excellent direct contact membrane distillation (DCMD) performance were fabricated by a facile route combining the hydrophobization of silica nanoparticles (SiO2 NPs) and colloid electrospinning of the hydrophobic silica/poly(vinylidene fluoride) (PVDF) matrix. Benefiting from the utilization of SiO2 NPs with three different particle sizes, the electrospun nanofibrous membranes (ENMs) were endowed with three different delicate nanofiber morphologies and fiber diameter distribution, high porosity, and superhydrophobic property, which resulted in excellent waterproofing and breathability. Significantly, structural attributes analyses have indicated the major contributing role of fiber diameter distribution on determining the augment of permeate vapor flux through regulating mean flow pore size (MFP). Meanwhile, the extremely high liquid entry pressure of water (LEPw, 2.40 ± 0.10 bar), robust nanofiber morphology of PVDF immobilized SiO2 NPs, remarkable mechanical properties, thermal stability, and corrosion resistance endowed the as-prepared membranes with prominent desalination capability and stability for long-term MD process. The resultant choreographed PVDF/silica ENMs with optimized MFP presented an outstanding permeate vapor flux of 41.1 kg/(m(2)·h) and stable low permeate conductivity (∼2.45 μs/cm) (3.5 wt % NaCl salt feed; ΔT = 40 °C) over a DCMD test period of 24 h without membrane pores wetting detected. This result was better than those of typical commercial PVDF membranes and PVDF and modified PVDF ENMs reported so far, suggesting them as promising alternatives for MD applications.

  7. Effect of driving frequency on actuation characteristics of ionic polymer-metal composites

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Yang, Y. W.

    2008-12-01

    In this paper, the effect of driving frequency on the actuation characteristics of ionic polymer-metal composites (IPMCs) is studied. The charge motion within the polyelectrolyte membrane under a dynamic electric potential is first formulated and investigated. Subsequently, the dynamic ion-ion interactions within the polyelectrolyte membrane clusters are studied. By analyzing the volumetric changes of the membrane clusters due to the electric field induced stresses and the elastic stresses in the backbones of the membrane, the bending moment expression due to the applied electric potential is obtained. By using this bending moment expression, the vibrations of an IPMC cantilevered beam subjected to electric potentials of different frequencies are calculated. The characteristics of the IPMCs behavior are discussed with comparison with experimental results.

  8. Ionic Polymer Metal Composites As Tactile Sensors

    NASA Astrophysics Data System (ADS)

    Mieney, Chris

    The field of electroactive polymers (EAPs) is rapidly growing. These materials are being scouted for use as linear actuators, specifically in the areas of artificial muscle design, and also for use as biomimetic sensors. IPMCs, or ionic polymer metal composites, are a form of EAP that are being proposed for application in both of these fields. IPMCs are composed of a solvated ionic EAP sandwiched between two metal electrodes. In the literature, there are a wealth of conceptual designs and data related to the use of IPMCs as actuators. However, sufficient data and characterization related to their use as sensors is grossly deficient. This research aims to rectify the gap between the theoretical concept of using these materials for sensing and actual proof of concept by quantifying voltage responses due to small force inputs in various electrolytes (LiCl, NiCl2, NiSO4, and De-Ionized water). Two different load profiles were implemented to evaluate the voltage response to a continuous input, to assess the feasibility of using IPMCs as a precision sensor, and to a cyclical input, to assess the feasibility of using IPMCs as a simpler binary sensor. Normal and reversed polarity voltage profiles were also collected to quantify the reversibility of the material response. Results from the study showed that the IPMCs showed a reversible response in all liquids tested. The results also showed that the response of the materials in LiCl was the least sensitive, but showed good repeatability, while the response in NiCl2 exhibited the greatest sensitivity, but the worst repeatability. The response in NiSO4 was slightly more sensitive than in LiCl and only slightly less repeatable, but the materials in NiSO4 demonstrated an almost completely reversible response. Interestingly, the response in DI water was only slightly less sensitive than in NiCl2 and results obtained using DI water demonstrated the feasibility of developing an IPMC sensor using DI water as the electrolyte

  9. Interaction of Cytotoxic and Cytoprotective Bile Acids with Model Membranes: Influence of the Membrane Composition.

    PubMed

    Esteves, M; Ferreira, M J; Kozica, A; Fernandes, A C; Gonçalves da Silva, A; Saramago, B

    2015-08-18

    To understand the role of bile acids (BAs) in cell function, many authors have investigated their effect on biomembrane models which are less complex systems, but there are still many open questions. The present study aims to contribute for the deepening of the knowledge of the interaction between BAs and model membranes, in particular, focusing on the effect of BA mixtures. The cytotoxic deoxycholic acid (DCA), the cytoprotective ursodeoxycholic acid (UDCA), and the equimolar mixture (DCA + UDCA) were investigated. Monolayers and liposomes were taken as model membranes with two lipid compositions: an equimolar mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM), and cholesterol (Chol)) traditionally associated with the formation of lipid rafts and an equimolar POPC/SM binary mixture. The obtained results showed that DCA causes the fluidization of monolayers and bilayers, leading to the eventual rupture of POPC/SM liposomes at high concentration. UDCA may provide a stabilization of POPC/SM membranes but has a negligible effect on the Chol-containing liposomes. In the case of equimolar mixture DCA/UDCA, the interactions depend not only on the lipid composition but also on the design of the experiment. The BA mixture has a greater impact on the monolayers than do pure BAs, suggesting a cooperative DCA-UDCA interaction that enhances the penetration of UDCA in both POPC/SM and POPC/SM/Chol monolayers. For the bilayers, the presence of UDCA in the mixture decreases the disturbing effect of DCA.

  10. Method for joining carbon-carbon composites to metals

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Moorhead, A.J.

    1997-07-15

    A method for joining carbon-carbon composites to metals by brazing. Conventional brazing of recently developed carbon-bonded carbon fiber (CBCF) material to a metal substrate is limited by the tendency of the braze alloy to ``wick`` into the CBCF composite rather than to form a strong bond. The surface of the CBCF composite that is to be bonded is first sealed with a fairly dense carbonaceous layer achieved by any of several methods. The sealed surface is then brazed to the metal substrate by vacuum brazing with a Ti-Cu-Be alloy. 1 fig.

  11. Method for joining carbon-carbon composites to metals

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Moorhead, Arthur J.

    1997-01-01

    A method for joining carbon-carbon composites to metals by brazing. Conventional brazing of recently developed carbon-bonded carbon fiber (CBCF) material to a metal substrate is limited by the tendency of the braze alloy to "wick" into the CBCF composite rather than to form a strong bond. The surface of the CBCF composite that is to be bonded is first sealed with a fairly dense carbonaceous layer achieved by any of several methods. The sealed surface is then brazed to the metal substrate by vacuum brazing with a Ti-Cu-Be alloy.

  12. Directly susceptible, noncarbon metal ceramic composite crucible

    DOEpatents

    Holcombe, Jr., Cressie E.; Kiggans, Jr., James O.; Morrow, S. Marvin; Rexford, Donald

    1999-01-01

    A sintered metal ceramic crucible suitable for high temperature induction melting of reactive metals without appreciable carbon or silicon contamination of the melt. The crucible comprises a cast matrix of a thermally conductive ceramic material; a perforated metal sleeve, which serves as a susceptor for induction heating of the crucible, embedded within the ceramic cast matrix; and a thermal-shock-absorber barrier interposed between the metal sleeve and the ceramic cast matrix to allow for differential thermal expansions between the matrix and the metal sleeve and to act as a thermal-shock-absorber which moderates the effects of rapid changes of sleeve temperature on the matrix.

  13. Membrane composition influences the topology bias of bacterial integral membrane proteins.

    PubMed

    Bay, Denice C; Turner, Raymond J

    2013-02-01

    Small multidrug resistance (SMR) protein family members confer bacterial resistance to toxic antiseptics and are believed to function as dual topology oligomers. If dual topology is essential for SMR activity, then the topology bias should change as bacterial membrane lipid compositions alter to maintain a "neutral" topology bias. To test this hypothesis, a bioinformatic analysis of bacterial SMR protein sequences was performed to determine a membrane protein topology based on charged amino acid residues within loops, and termini regions according to the positive inside rule. Three bacterial lipid membrane parameters were examined, providing the proportion of polar lipid head group charges at the membrane surface (PLH), the relative hydrophobic fatty acid length (FAL), and the proportion of fatty acid unsaturation (FAU). Our analysis indicates that individual SMR pairs, and to a lesser extent SMR singleton topology biases, are significantly correlated to increasing PLH, FAL and FAU differences validating the hypothesis. Correlations between the topology biases of SMR proteins identified in Gram+ compared to Gram- species and each lipid parameter demonstrated a linear inverse relationship.

  14. Method of making metal oxide ceramic membranes with small pore sizes

    DOEpatents

    Anderson, Marc A.; Xu, Qunyin

    1992-01-01

    A method for the production of metal oxide ceramic membranes is composed of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

  15. Charge dynamics in ionic polymer metal composites

    NASA Astrophysics Data System (ADS)

    Porfiri, Maurizio

    2008-11-01

    In this paper, we study the charge dynamics in ionic polymer metal composites (IPMCs) in response to a voltage difference applied across their electrodes. We use the Poisson-Nernst-Planck equations to model the time evolution of the electric potential and the concentration of mobile counterions. We present an analytical solution of the nonlinear initial-boundary value problem by using matched asymptotic expansions. We determine the charge and electric potential distributions as functions of time in the whole IPMC region. We show that in the bulk polymer region the IPMC is approximately electroneutral; in contrast, charge distribution boundary layers arise at the polymer-electrode interfaces. Prominent charge depletion and enrichment at the polymer-electrode interface are present even at moderately low input-voltage levels. We use the proposed analytical solution to derive a physics-based circuit model of IPMCs. The equivalent circuit comprises a linear resistor in series connection with a nonlinear capacitor. We derive closed-form expressions for the resistance and the capacitance by conducting a qualitative phase-plane analysis of the inner approximation of the asymptotic expansion. The circuit conductivity is independent of the IPMC dielectric constant and is proportional to the ion diffusivity; whereas, the capacitance is proportional to the square root of the dielectric constant and is independent of the diffusivity. The conductivity depends on the polymer thickness, while the capacitance is independent of it. The capacitance nonlinearity is extremely pronounced, and dramatic capacitance reduction is observed for moderately low voltage levels. We validate the proposed analytical solution along with the derived circuit model through extensive comparisons with finite element results available in the technical literature.

  16. Removal and recovery of heavy metals from wastewaters by supported liquid membranes.

    PubMed

    Yang, X J; Fane, A G; MacNaughton, S

    2001-01-01

    The removal and recovery of Cu, Cr and Zn from plating rinse wastewater using supported liquid membranes (SLM) are investigated. SLMs with specific organic extractants as the liquid membrane carriers in series are able to remove and concentrate heavy metals with very high purity, which is very promising for recycling of heavy metals in the electroplating industry. A technical comparison between the membrane process and the conventional chemical precipitation process was made.

  17. Thermoelectric metal comparator determines composition of alloys and metals

    NASA Technical Reports Server (NTRS)

    Stone, C. C.; Walker, D. E.

    1967-01-01

    Emf comparing device nondestructively inspects metals and alloys for conformance to a chemical specification. It uses the Seebeck effect to measure the difference in emf produced by the junction of a hot probe and the junction of a cold contact on the surface of an unknown metal.

  18. A fabrication approach of ionic polymer-metal composite for deformation sensors

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Tan, Yonghong; Dong, Ruili; He, Hong

    2015-11-01

    In this paper a fabrication method of ionic polymer-metal composite for deformation sensors is proposed. In this method, the Nafion film is sandwiched in between the electrodes made by foils of cheaper metal. Then, the IPMC is covered by protecting coating in order to keep the solution in the Nafion membrane from evaporation so as to derive stable operation performance when it works in dry air environment. Based on the Nernst equation, the electrical potential difference between two electrodes is determined by the ion concentration difference in the clearance inside and near the electrodes.

  19. Amino acid composition analysis of human secondary transport proteins and implications for reliable membrane topology prediction.

    PubMed

    Saidijam, Massoud; Azizpour, Sonia; Patching, Simon G

    2016-07-08

    Secondary transporters in humans are a large group of proteins that transport a wide range of ions, metals, organic and inorganic solutes involved in energy transduction, control of membrane potential and osmotic balance, metabolic processes and in the absorption or efflux of drugs and xenobiotics. They are also emerging as important targets for development of new drugs and as target sites for drug delivery to specific organs or tissues. We have performed amino acid composition (AAC) and phylogenetic analyses and membrane topology predictions for 336 human secondary transport proteins and used the results to confirm protein classification and to look for trends and correlations with structural domains and specific substrates and/or function. Some proteins showed statistically high contents of individual amino acids or of groups of amino acids with similar physicochemical properties. One recurring trend was a correlation between high contents of charged and/or polar residues with misleading results in predictions of membrane topology, which was especially prevalent in Mitochondrial Carrier family proteins. We demonstrate how charged or polar residues located in the middle of transmembrane helices can interfere with their identification by membrane topology tools resulting in missed helices in the prediction. Comparison of AAC in the human proteins with that in 235 secondary transport proteins from Escherichia coli revealed similar overall trends along with differences in average contents for some individual amino acids and groups of similar amino acids that are presumed to result from a greater number of functions and complexity in the higher organism.

  20. Rhodococcus erythropolis cells adapt their fatty acid composition during biofilm formation on metallic and non-metallic surfaces.

    PubMed

    Rodrigues, Carlos J C; de Carvalho, Carla C C R

    2015-12-01

    Several parameters are involved in bacterial adhesion and biofilm formation including surface type, medium composition and cellular surface hydrophobicty. When the cells are placed inside tubes, parameters such as oxygen availability should also influence cell adhesion. To understand which cellular lipids are involved in the molecular events of biofilm formation in Rhodococcus erythropolis, cell adhesion was promoted on different metallic and non-metallic surfaces immersed in culture media. These cells were able to modulate the fatty acid composition of the cell membrane in response to both the surface to which they adhered and the growth medium used. To assess the response of the cells to both surfaces and operational conditions, biofilms were also promoted inside a reactor built with five different types of tubes and with medium recirculation. The biofilm biomass could be directly related not to the hydrophobicity of the tubes used but to the oxygen permeability of the tubes. Besides this, cell age influenced the adhesion of the R. erythropolis cells to the tubes. Principal component analysis showed that the lipid composition of the cells could separate cells attached to metallic from those on non-metallic surfaces in the plane formed by PC1 and PC2, and influence biofilm biomass.

  1. Experimental investigations on mechanical behavior of aluminium metal matrix composites

    NASA Astrophysics Data System (ADS)

    Rajesh, A. M.; Kaleemulla, Mohammed

    2016-09-01

    Today we are widely using aluminium based metal matrix composite for structural, aerospace, marine and automobile applications for its light weight, high strength and low production cost. The purpose of designing metal matrix composite is to add the desirable attributes of metals and ceramics to the base metal. In this study we developed aluminium metal matrix hybrid composite by reinforced Aluminium7075 alloy with silicon carbide (SiC) and aluminium oxide (alumina) by method of stir casting. This technique is less expensive and very effective. The Hardness test and Wear test were performed on the specimens which are prepared by stir casting techniques. The result reveals that the addition of silicon carbide and alumina particles in aluminium matrix improves the mechanical properties.

  2. Metal oxide composite dosimeter method and material

    DOEpatents

    Miller, Steven D.

    1998-01-01

    The present invention is a method of measuring a radiation dose wherein a radiation responsive material consisting essentially of metal oxide is first exposed to ionizing radiation. The metal oxide is then stimulating with light thereby causing the radiation responsive material to photoluminesce. Photons emitted from the metal oxide as a result of photoluminescence may be counted to provide a measure of the ionizing radiation.

  3. Metal matrix composite structural panel construction

    NASA Technical Reports Server (NTRS)

    Mcwithey, R. R.; Royster, D. M. (Inventor); Bales, T. T.

    1983-01-01

    Lightweight capped honeycomb stiffeners for use in fabricating metal or metal/matrix exterior structural panels on aerospace type vehicles and the process for fabricating same are disclosed. The stiffener stringers are formed in sheets, cut to the desired width and length and brazed in spaced relationship to a skin with the honeycomb material serving directly as the required lightweight stiffeners and not requiring separate metal encasement for the exposed honeycomb cells.

  4. Outer membrane vesicles of Tannerella forsythia: biogenesis, composition, and virulence.

    PubMed

    Friedrich, V; Gruber, C; Nimeth, I; Pabinger, S; Sekot, G; Posch, G; Altmann, F; Messner, P; Andrukhov, O; Schäffer, C

    2015-12-01

    Tannerella forsythia is the only 'red-complex' bacterium covered by an S-layer, which has been shown to affect virulence. Here, outer membrane vesicles (OMVs) enriched with putative glycoproteins are described as a new addition to the virulence repertoire of T. forsythia. Investigations of this bacterium are hampered by its fastidious growth requirements and the recently discovered mismatch of the available genome sequence (92A2 = ATCC BAA-2717) and the widely used T. forsythia strain (ATCC 43037). T. forsythia was grown anaerobically in serum-free medium and biogenesis of OMVs was analyzed by electron and atomic force microscopy. This revealed OMVs with a mean diameter of ~100 nm budding off from the outer membrane while retaining the S-layer. An LC-ESI-TOF/TOF proteomic analysis of OMVs from three independent biological replicates identified 175 proteins. Of these, 14 exhibited a C-terminal outer membrane translocation signal that directs them to the cell/vesicle surface, 61 and 53 were localized to the outer membrane and periplasm, respectively, 22 were predicted to be extracellular, and 39 to originate from the cytoplasm. Eighty proteins contained the Bacteroidales O-glycosylation motif, 18 of which were confirmed as glycoproteins. Release of pro-inflammatory mediators from the human monocytic cell line U937 and periodontal ligament fibroblasts upon stimulation with OMVs followed a concentration-dependent increase that was more pronounced in the presence of soluble CD14 in conditioned media. The inflammatory response was significantly higher than that caused by whole T. forsythia cells. Our study represents the first characterization of T. forsythia OMVs, their proteomic composition and immunogenic potential.

  5. Steel-SiC Metal Matrix Composite Development

    SciTech Connect

    Smith, Don D.

    2005-07-17

    The goal of this project is to develop a method for fabricating SiC-reinforced high-strength steel. We are developing a metal-matrix composite (MMC) in which SiC fibers are be embedded within a metal matrix of steel, with adequate interfacial bonding to deliver the full benefit of the tensile strength of the SiC fibers in the composite.

  6. Ionic polymer metal composites with nanoporous carbon electrodes

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar; Brandell, Daniel; Mäeorg, Uno; Torop, Janno; Volobujeva, Olga; Punning, Andres; Johanson, Urmas; Aabloo, Alvo

    2010-04-01

    Ionic Polymer Metal Composites (IPMCs) are soft electroactive polymer materials that bend in response to the voltage stimulus (1 - 4 V). They can be used as actuators or sensors. In this paper, we introduce two new highly-porous carbon materials for assembling high specific area electrodes for IPMC actuators and compare their electromechanical performance with recently reported IPMCs based on RuO2 electrodes. We synthesize ionic liquid (Emi-Tf) actuators with either Carbide-Derived Carbon (CDC) (derived from TiC) or coconut shell based activated carbon electrodes. The carbon electrodes are applied onto ionic liquid-swollen Nafion membranes using the direct assembly process. Our results show that actuators assembled with CDC electrodes have the greatest peak-to-peak strain output, reaching up to 20.4 mɛ (equivalent to >2%) at a 2 V actuation signal, exceeding that of the RuO2 electrodes by more than 100%. The electrodes synthesized from TiC-derived carbon also revealed significantly higher maximum strain rate. The differences between the materials are discussed in terms of molecular interactions and mechanisms upon actuation in the different electrodes.

  7. [Study on spectroscopic characterization and property of PES/ micro-nano cellulose composite membrane material].

    PubMed

    Tang, Huan-Wei; Zhang, Li-Ping; Li, Shuai; Zhao, Guang-Jie; Qin, Zhu; Sun, Su-Qin

    2010-03-01

    In the present paper, the functional groups of PES/micro-nano cellulose composite membrane materials were characterized by Fourier transform infrared spectroscopy (FTIR). Also, changes in crystallinity in composite membrane materials were analyzed using X-ray diffraction (XRD). The effects of micro-nano cellulose content on hydrophilic property of composite membrane material were studied by measuring hydrophilic angle. The images of support layer structure of pure PES membrane material and composite membrane material were showed with scanning electron microscope (SEM). These results indicated that in the infrared spectrogram, the composite membrane material had characteristic peaks of both PES and micro-nano cellulose without appearance of other new characteristics peaks. It revealed that there were no new functional groups in the composite membrane material, and the level of molecular compatibility was achieved, which was based on the existence of inter-molecular hydrogen bond association between PES and micro-nano cellulose. Due to the existence of micro-nano cellulose, the crystallinity of composite membrane material was increased from 37.7% to 47.9%. The more the increase in micro-nano cellulose mass fraction, the better the van de Waal force and hydrogen bond force between composite membrane material and water were enhanced. The hydrophilic angle of composite membrane material was decreased from 55.8 degrees to 45.8 degrees and the surface energy was raised from 113.7 to 123.5 mN x m(-2). Consequently, the hydrophilic property of composite membrane material was improved. The number of pores in the support layer of composite membrane material was lager than that of pure PES membrane. Apparently, pores were more uniformly distributed.

  8. Modelling compression sensing in ionic polymer metal composites

    NASA Astrophysics Data System (ADS)

    Volpini, Valentina; Bardella, Lorenzo; Rodella, Andrea; Cha, Youngsu; Porfiri, Maurizio

    2017-03-01

    Ionic polymer metal composites (IPMCs) consist of an ionomeric membrane, including mobile counterions, sandwiched between two thin noble metal electrodes. IPMCs find application as sensors and actuators, where an imposed mechanical loading generates a voltage across the electrodes, and, vice versa, an imposed electric field causes deformation. Here, we present a predictive modelling approach to elucidate the dynamic sensing response of IPMCs subject to a time-varying through-the-thickness compression (‘compression sensing’). The model relies on the continuum theory recently developed by Porfiri and co-workers, which couples finite deformations to the modified Poisson–Nernst–Planck (PNP) system governing the IPMC electrochemistry. For the ‘compression sensing’ problem we establish a perturbative closed-form solution along with a finite element (FE) solution. The systematic comparison between these two solutions is a central contribution of this study, offering insight on accuracy and mathematical complexity. The method of matched asymptotic expansions is employed to find the analytical solution. To this end, we uncouple the force balance from the modified PNP system and separately linearise the PNP equations in the ionomer bulk and in the boundary layers at the ionomer–electrode interfaces. Comparison with FE results for the fully coupled nonlinear system demonstrates the accuracy of the analytical solution to describe IPMC sensing for moderate deformation levels. We finally demonstrate the potential of the modelling scheme to accurately reproduce experimental results from the literature. The proposed model is expected to aid in the design of IPMC sensors, contribute to an improved understanding of IPMC electrochemomechanical response, and offer insight into the role of nonlinear phenomena across mechanics and electrochemistry.

  9. Gel bead composition for metal adsorption

    SciTech Connect

    Scott, C.D.; Woodward, C.A.; Byers, C.H.

    1990-12-18

    This patent describes a gel bead consisting essentially of a sufficient amount of water and propylene glycol alginate to allow for bead formation and a sufficient amount of bone gelatin to allow for metal absorption and chemically crosslinked in an alkaline medium to form a stable structure. A gel bead contained therein a biological absorbent capable of removing metals from solution.

  10. Compositions and methods for removal of toxic metals and radionuclides

    NASA Technical Reports Server (NTRS)

    Cuero, Raul G. (Inventor); McKay, David S. (Inventor)

    2007-01-01

    The present invention relates to compositions and methods for the removal of toxic metals or radionuclides from source materials. Toxic metals may be removed from source materials using a clay, such as attapulgite or highly cationic bentonite, and chitin or chitosan. Toxic metals may also be removed using volcanic ash alone or in combination with chitin or chitosan. Radionuclides may be removed using volcanic ash alone or in combination with chitin or chitosan.

  11. Membrane permeable luminescent metal complexes for cellular imaging

    NASA Astrophysics Data System (ADS)

    Neugebauer, Ute; Cosgrave, Lynda; Pellegrin, Yann; Devocelle, Marc; Forster, Robert J.; Keyes, Tia E.

    2012-06-01

    The spectroscopic and photophysical properties of ruthenium polypyridyl polypeptide conjugates of the type [Ru(bpy)2PIC-Argn]n+2+, where bpy is 2,2-bipyridyl (bpy), PIC is 2-(4-carboxyphenyl)imidazo[4,5- f][1,10]phenanthroline and PIC-Argn is this ligand peptide bonded to polyarginine where n is 5 or 8, is described. The resonance Raman spectroscopy of the peptide conjugated complex and parent are strongly pH dependent and demonstrate a switch of lowest energy charge transfer transition between bpy and pic ligands as s function of pH. The pKa of the imidazole ring on the complex is obtained from resonance Raman spectroscopy as 7.8 +/- 0.2. The luminescence lifetime of the complex is strongly oxygen dependent and a Stern-Volmer plot of O2 quenching for [Ru(bpy)2(PIC-Arg8)]10+ yielded a KSV value of 2300 +/- 420 M-1 which was independent of pH over the range 2 to 11. The complexes, because of their large Stokes shifts can, uniquely, be used under identical conditions of probe concentration and excitation wavelength for resonance Raman and luminescence cellular imaging. Cellular imaging was conducted using SP2 myeloma cells which confirmed that the [Ru(bpy)2(PIC-Arg8)]10+ is readily taken up by mammalian cells although the parent and pentarginine analogues are not membrane permeable. Preliminary examples of multi-parameter imaging using these probes were presented. Resonance Raman maps of [Ru(bpy)2(PIC-Arg8)]10+ within living myeloma cells showed on the basis of spectral discrimination, attributed to pH, three distinct regions of the cell could be identified, ascribed to the nucleus, the cytoplasm and the membranes. Luminescence lifetime imaging showed quite large variations in the probe lifetime within the living cell which was tentatively ascribed to variation in O2 concentration about the cell. Preliminary estimates of O2 concentration were made and it was found that the membranes, both inner and outer are the most O2 rich regions of the cell. Overall, we propose

  12. Polyrhodanine modified anodic aluminum oxide membrane for heavy metal ions removal.

    PubMed

    Song, Jooyoung; Oh, Hyuntaek; Kong, Hyeyoung; Jang, Jyongsik

    2011-03-15

    Polyrhodanine was immobilized onto the inner surface of anodic aluminum oxide (AAO) membrane via vapor deposition polymerization method. The polyrhodanine modified membrane was applied to remove heavy metal ions from aqueous solution because polyrhodanine could be coordinated with specific metal ions. Several parameters such as initial metal concentration, contact time and metal species were evaluated systematically for uptake efficiencies of the fabricated membrane under continuous flow condition. Adsorption isotherms of Hg(II) ion on the AAO-polyrhodanine membrane were analyzed with Langmuir and Freundlich isotherm models. The adsorption rate of Hg(II) ion on the membrane was obeyed by a pseudo-second order equation, indicating the chemical adsorption. The maximum removal capacity of Hg(II) ion onto the fabricated membrane was measured to be 4.2 mmol/g polymer. The AAO-polyrhodanine membrane had also remarkable uptake performance toward Ag(I) and Pb(II) ions. Furthermore, the polyrhodanine modified membrane could be recycled after recovery process. These results demonstrated that the polyrhodanine modified AAO membrane provided potential applications for removing the hazardous heavy metal ions from wastewater.

  13. Exploring the potential of membrane bioreactors to enhance metals removal from wastewater: pilot experiences.

    PubMed

    Fatone, F; Eusebi, A L; Pavan, P; Battistoni, P

    2008-01-01

    The potential of membrane bioreactors to enhance the removal of selected metals from low loaded sewages has been explored. A 1400 litre pilot plant, equipped with an industrial submerged module of hollow fibre membranes, has been used in three different configurations: membrane bioreactor, operating in sequencing batch modality, for the treatment of real mixed municipal/industrial wastewater; membrane-assisted biosorption reactor, for the treatment of real leachate from municipal landfills; continuously fed membrane bioreactor, for the treatment of water charged with cadmium and nickel ions. The results show that: (a) in treating wastewaters with low levels of heavy metals (< one milligram per litre concentration), operating high sludge ages is not an effective strategy to significantly enhance the metals removal; (b) Hg and Cd are effectively removed already in conventional systems with gravitational final clarifiers, while Cu, Cr, Ni can rely on a additional performance in membrane bioreactors; (c) the further membrane effect is remarkable for Cu and Cr, while it is less significant for Ni. Basically, similar membrane effects recur in three different experimental applications that let us estimate the potential of membrane system to retain selected metal complexes. The future development of the research will investigate the relations between the membrane effect and the manipulable filtration parameters (i.e., permeate flux, solids content, filtration cycle).

  14. Performance evaluation and characterization of metallic bipolar plates in a proton exchange membrane (PEM) fuel cell

    NASA Astrophysics Data System (ADS)

    Hung, Yue

    Bipolar plate and membrane electrode assembly (MEA) are the two most repeated components of a proton exchange membrane (PEM) fuel cell stack. Bipolar plates comprise more than 60% of the weight and account for 30% of the total cost of a fuel cell stack. The bipolar plates perform as current conductors between cells, provide conduits for reactant gases, facilitate water and thermal management through the cell, and constitute the backbone of a power stack. In addition, bipolar plates must have excellent corrosion resistance to withstand the highly corrosive environment inside the fuel cell, and they must maintain low interfacial contact resistance throughout the operation to achieve optimum power density output. Currently, commercial bipolar plates are made of graphite composites because of their relatively low interfacial contact resistance (ICR) and high corrosion resistance. However, graphite composite's manufacturability, permeability, and durability for shock and vibration are unfavorable in comparison to metals. Therefore, metals have been considered as a replacement material for graphite composite bipolar plates. Since bipolar plates must possess the combined advantages of both metals and graphite composites in the fuel cell technology, various methods and techniques are being developed to combat metallic corrosion and eliminate the passive layer formed on the metal surface that causes unacceptable power reduction and possible fouling of the catalyst and the electrolyte. The main objective of this study was to explore the possibility of producing efficient, cost-effective and durable metallic bipolar plates that were capable of functioning in the highly corrosive fuel cell environment. Bulk materials such as Poco graphite, graphite composite, SS310, SS316, incoloy 800, titanium carbide and zirconium carbide were investigated as potential bipolar plate materials. In this work, different alloys and compositions of chromium carbide coatings on aluminum and SS316

  15. Joining and fabrication of metal-matrix composite materials

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Wiant, H. R.; Bales, T. T.

    1975-01-01

    Manufacturing technology associated with developing fabrication processes to incorporate metal-matrix composites into flight hardware is studied. The joining of composite to itself and to titanium by innovative brazing, diffusion bonding, and adhesive bonding is examined. The effects of the fabrication processes on the material properties and their influence on the design of YF-12 wing panels are discussed.

  16. Metal-dielectric composite for dispersion free optics

    NASA Astrophysics Data System (ADS)

    Balasubrahmaniyam, M.; Patra, Anuradha; Ganesan, A. R.; Kasiviswanathan, S.

    2013-02-01

    Bergman formulation has been used to extract effective dielectric function of Au nanoparticles (AuNPs) embedded metal oxide (MO) composite thin films. The extracted composite dielectric function helps further understanding ofthe resonance features in optical far-field responses. Detailed analysis on the extracted dielectric functions point towards the possibility of using them for dispersion free optics.

  17. FIBER-REINFORCED METALLIC COMPOSITE MATERIALS.

    DTIC Science & Technology

    COMPOSITE MATERIALS), (*FIBER METALLURGY, TITANIUM ALLOYS , NICKEL ALLOYS , REINFORCING MATERIALS, TUNGSTEN, WIRE, MOLYBDENUM ALLOYS , COBALT ALLOYS , CHROMIUM ALLOYS , ALUMINUM ALLOYS , MECHANICAL PROPERTIES, POWDER METALLURGY.

  18. Chitosan/silica coated carbon nanotubes composite proton exchange membranes for fuel cell applications.

    PubMed

    Liu, Hai; Gong, Chunli; Wang, Jie; Liu, Xiaoyan; Liu, Huanli; Cheng, Fan; Wang, Guangjin; Zheng, Genwen; Qin, Caiqin; Wen, Sheng

    2016-01-20

    Silica-coated carbon nanotubes (SCNTs), which were obtained by a simple sol-gel method, were utilized in preparation of chitosan/SCNTs (CS/SCNTs) composite membranes. The thermal and oxidative stability, morphology, mechanical properties, water uptake and proton conductivity of CS/SCNTs composite membranes were investigated. The insulated and hydrophilic silica layer coated on CNTs eliminates the risk of electronic short-circuiting and enhances the interaction between SCNTs and chitosan to ensure the homogenous dispersion of SCNTs, although the water uptake of CS/SCNTs membranes is reduced owing to the decrease of the effective number of the amino functional groups of chitosan. The CS/SCNTs composite membranes are superior to the pure CS membrane in thermal and oxidative stability, mechanical properties and proton conductivity. The results of this study suggest that CS/SCNTs composite membranes exhibit promising potential for practical application in proton exchange membranes.

  19. Design of poly(ether block amide)/polyacrylonitrile composite membrane for carbon dioxide capture

    NASA Astrophysics Data System (ADS)

    Wang, Lianjun; Ji, Pengfei; Li, Yang; di, Mingming; Lv, Quan; Li, Shuguang

    2015-03-01

    In this study, poly(ether block amide) was used as coating material to develop a novel composite polymer membrane for CO2 capture. Polyacrylonitrile (PAN) ultrafiltration membrane was applied as substrate. Between them, a gutter layer prepared from cross-linked polydimethylsiloxane (PDMS) blending with amino silicone was introduced to improve separation performance of the composite membrane. The separation properties of resultant triple layer composite membrane was characterized using pure CO2 and N2 gases. It was found that the crosslinking degree of the gutter layer had great influence on membrane performance, which could be significantly improved with the help of amino-PDMS gutter layer compared with that of the membrane having Pebax coating directly onto PAN substrate. Using 2 wt.% Pebax coating solution and properly cross-linked gutter layer, the designed Pebax/amino-PDMS/PAN composite membrane showed CO2 permeance of 147 GPU and CO2/N2 selectivity of 62.

  20. Alginate Hydrogel: A Shapeable and Versatile Platform for in Situ Preparation of Metal-Organic Framework-Polymer Composites.

    PubMed

    Zhu, He; Zhang, Qi; Zhu, Shiping

    2016-07-13

    This work reports a novel in situ growth approach for incorporating metal-organic framework (MOF) materials into an alginate substrate, which overcomes the challenges of processing MOF particles into specially shaped structures for real industrial applications. The MOF-alginate composites are prepared through the post-treatment of a metal ion cross-linked alginate hydrogel with a MOF ligand solution. MOF particles are well distributed and embedded in and on the surface of the composites. The macroscopic shape of the composite can be designed by controlling the shape of the corresponding hydrogel; thus MOF-alginate beads, fibers, and membranes are obtained. In addition, four different MOF-alginate composites, including HKUST-1-, ZIF-8-, MIL-100(Fe)-, and ZIF-67-alginate, were successfully prepared using different metal ion cross-linked alginate hydrogels. The mechanism of formation is revealed, and the composite is demonstrated to be an effective absorbent for water purification.

  1. Metal Compression Forming of aluminum alloys and metal matrix composites

    SciTech Connect

    Viswanathan, S.; Ren, W.; Porter, W.D.; Brinkman, C.R.; Sabau, A.S.; Purgert, R.M.

    2000-02-01

    Metal Compression Forming (MCF) is a variant of the squeeze casting process, in which molten metal is allowed to solidify under pressure in order to close porosity and form a sound part. However, the MCF process applies pressure on the entire mold face, thereby directing pressure on all regions of the casting and producing a uniformly sound part. The process is capable of producing parts with properties close to those of forgings, while retaining the near net shape, complexity in geometry, and relatively low cost of the casting process.

  2. Importance of the support material in thin palladium composite membranes for steady hydrogen permeation at elevated temperatures.

    PubMed

    Okazaki, Junya; Ikeda, Takuji; Pacheco Tanaka, David A; Llosa Tanco, Margot A; Wakui, Yoshito; Sato, Koich; Mizukami, Fujio; Suzuki, Toshishige M

    2009-10-14

    Hydrogen permeation performance of palladium membranes supported on porous alpha-alumina and yttria-stabilized zirconia (YSZ) was studied at 300-850 degrees C. The hydrogen permeation flux across the palladium-alpha-alumina membrane decreased markedly during permeation tests conducted at >600 degrees C. The SEM and XPS studies of the post-test membrane revealed the presence of aluminium in the palladium layer. Such migration of aluminium was not observed by heating the palladium-alpha-alumina membrane under an argon atmosphere, indicating that hydrogen is responsible for this phenomenon. Hydrogen-induced strong metal-support interaction might be related to this considerable loss of the hydrogen flux. Reduction of alumina to Al(0) by active hydrogen at the membrane-support interface and subsequent migration of Al(0) into the palladium layer represents the most plausible mechanism for the aluminium diffusion. Actually, Al(0) that migrated into the palladium membrane layer generated less hydrogen-permeable palladium-aluminium alloy or inter-metallic compound phase. In contrast, no such strong interaction was found between the YSZ support and the palladium membrane. This composite membrane exhibited a steady permeation of hydrogen at 650 degrees C for 336 h. Having a remarkably high reduction potential, Y(III) is unlikely to be reduced to Y(0), although Zr(IV) has a comparable reduction potential to that of Al(III). A binary phase diagram shows a liquid alloy phase present for the Pd/Al couple at temperatures greater than 615 degrees C (eutectic point), while an inter-metallic compound or liquid alloy phase in the Pd-Zr binary system is not apparent at temperatures less than 750 degrees C. Consequently, inter-diffusion of zirconium with palladium did not occur during operations at 650 degrees C.

  3. Composite metal foil and ceramic fabric materials

    DOEpatents

    Webb, Brent J.; Antoniak, Zen I.; Prater, John T.; DeSteese, John G.

    1992-01-01

    The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed.

  4. Composite metal foil and ceramic fabric materials

    DOEpatents

    Webb, B.J.; Antoniak, Z.I.; Prater, J.T.; DeSteese, J.G.

    1992-03-24

    The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed. 11 figs.

  5. New composite membranes based on modified Nafion or Flemion for PEM fuel cell application

    NASA Astrophysics Data System (ADS)

    Tian, Huimin

    A new composite membrane based on Nafion or Flemion and Silicotungstic acid (STA) was fabricated using a simple solvent evaporation procedure. The optimum evaporation temperature and the amount of STA have been investigated. The evaporation of solvent can be divided into two steps during membrane preparation. Firstly, the solvent was evaporated at 70°C for two hours. Secondly, the evaporated membrane was kept in an vacuum oven at 135°C overnight. The optimum amount of STA in the casting electrolyte solution is in the range from 5 x 10-4 to 5 x 10-3 M. The obtained cast composite membranes exhibit good thermal and mechanical properties. Study of the ionic conductivity shows that the composite membrane with STA gives a higher ionic conductivity than that without STA. The conductivity of composite membrane increases with the increase of STA concentration. When the STA concentration in the 10mL casting electrolyte solution is 5 x 10-3M, the conductivities of the composite membranes can reach up to 0.120 ohm-1 · cm-1 for Nafion/STA membrane and 0.133 ohm -1 · cm-1 for Flemion/STA membrane. On the other hand, the water uptake measurement shows that the water content of the composite membrane with STA is higher than that of composite membrane without STA. Consequently, due to the high conductivity and the high hydrated abiliy of STA, ionic conductivity and water uptake of the composite membrane can be significantly improved by the addition of STA. The morphology of the composite membrane was studied using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results of AFM and SEM showed that the STA was uniformly dispersed in the Nafion and Flemion composite membranes. The structure of a composite membrane with STA has been studied by X-ray diffraction (XRD), the fourier transform infrared spectroscopy (FTIR), thermoanalysis and X-ray photoelectron spectroscopy (XPS). The results indicated that STA was successfully introduced into the structure of

  6. Intrinsic manufacture of hollow thermoplastic composite/metal structures

    NASA Astrophysics Data System (ADS)

    Barfuss, Daniel; Grützner, Raik; Garthaus, Christian; Gude, Maik; Müller, Roland; Langrebe, Dirk

    2016-10-01

    In contrast to common and classical joining technologies for composite/metal hybrid structures such as bonding and riveting, profile and contour joints offer a promising potential for novel lightweight hybrid structures. First and foremost, joining systems with a form closure function enable to pass very high loads into rod- and tube-shaped fibre reinforced structures and achieve high degrees of material utilization for the composite part. This paper demonstrates the theoretical and technological principals for a resource efficient design and production of highly loaded thermoplastic composite profile structures with integrated metallic load introduction elements and a multi scale form closure. The hybrid structures are produced in an integral blow moulding process in which a braided tape-preform is simultaneously consolidated and formed into the metallic load introduction element. These metallic load introduction elements are manufactured in a two-stage process of external and internal hydroforming, after forming simulations have assured process stability for consistent quality.

  7. Metals Ions Removal by Polymer Membranes of Different Porosity

    PubMed Central

    2013-01-01

    The effect of the amount of pore generating agent (polyvinylpyrrolidone) added to standard polymer membranes containing 18 wt.% of polyethersulfone on the physicochemical properties of the membranes and their capacity for removal of iron and copper ions from the liquid phase was studied. The membranes were obtained by the phase inversion method. The results have shown that the modification of polymer membranes by the use of different amounts of the pore forming agent in their syntheses leads to significant changes in porosity and has beneficial effect on equilibrium water content. The membranes studied were found to show different acid-base surface character, but for all membranes studied, a significant dominance of oxygen groups of acidic character was evidenced. The most effective were the membranes of the lowest content of polyvinylpyrrolidone, while the lowest values of resistance showed the membranes of the highest content of PVP, and so the ones of the greatest porosity. PMID:23818836

  8. Wear resistance and wear mechanisms in polymer + metal composites.

    PubMed

    Olea-Mejia, Oscar; Brostow, Witold; Buchman, Eli

    2010-12-01

    We have investigated composites containing metallic micro-size and nano-sized particles as the 10 wt% dispersed phase. Branched low density polyethylene (LDPE) was the matrix. Microsized metals were Al, Ag and Ni; nanosized metals were Al and Ag. Several mechanisms of wear are observed in function of the kind and size of metal used: deformation, delamination, abrasion, adhesion and rolls formation. The presence of Ag particles increases the wear rate as compared to neat LDPE. The presence of Al particles lowers the wear of LDPE significantly; nanoparticles are more effective than microparticles.

  9. Aminoalcohol functionalized zirconium phosphate as versatile filler for starch-based composite membranes.

    PubMed

    Pica, Monica; Donnadio, Anna; Bianchi, Valentina; Fop, Sacha; Casciola, Mario

    2013-08-14

    Microcrystalline zirconium phosphate was exfoliated by treatment with aqueous solutions of α,ω-alkylaminoalcohols and employed for the fabrication of potato starch composite membranes. Glycerol-based and glycerol-free composite membranes, containing 5 wt% of filler, were prepared from gelatinized starch and characterized for their physico-chemical properties. Despite of a partial filler reaggregation, as revealed by XRD and SEM analysis, all the composites exhibited a significant increase in the Young's modulus with respect to the glycerol-starch membrane, up to 80% and 190% for the glycerol-based and the glycerol-free composites, respectively. For both kinds of membranes the filler delays to a large extent the starch decomposition above about 300°C. A significant reduction in the water uptake of the composites was also observed with respect to the neat glycerol-based membrane, up to about 70% for the glycerol-free composites.

  10. Chemical and microstructural analyses for heavy metals removal from water media by ceramic membrane filtration.

    PubMed

    Ali, Asmaa; Ahmed, Abdelkader; Gad, Ali

    2017-01-01

    This study aims to investigate the ability of low cost ceramic membrane filtration in removing three common heavy metals namely; Pb(2+), Cu(2+), and Cd(2+) from water media. The work includes manufacturing ceramic membranes with dimensions of 15 by 15 cm and 2 cm thickness. The membranes were made from low cost materials of local clay mixed with different sawdust percentages of 0.5%, 2.0%, and 5.0%. The used clay was characterized by X-ray diffraction (XRD) and X-ray fluorescence analysis. Aqueous solutions of heavy metals were prepared in the laboratory and filtered through the ceramic membranes. The influence of the main parameters such as pH, initial driving pressure head, and concentration of heavy metals on their removal efficiency by ceramic membranes was investigated. Water samples were collected before and after the filtration process and their heavy metal concentrations were determined by chemical analysis. Moreover, a microstructural analysis using scanning electronic microscope (SEM) was performed on ceramic membranes before and after the filtration process. The chemical analysis results showed high removal efficiency up to 99% for the concerned heavy metals. SEM images approved these results by showing adsorbed metal ions on sides of the internal pores of the ceramic membranes.

  11. Preparation and Properties of Nano-Hydroxyapatite/Gelatin/Poly(vinyl alcohol) Composite Membrane.

    PubMed

    Liao, Haotian; Shi, Kun; Peng, Jinrong; Qu, Ying; Liao, Jinfeng; Qian, Zhiyong

    2015-06-01

    In this study, the bone-like composite membrane based on blends of gelatin (Gel), nano-hydroxyapatite (n-HA) and poly(vinyl alcohol) (PVA) was fabricated by solvent casting and evaporation methods. The effect of n-HA content and the ratio of Gel/PVA on the properties of the composite was investigated. The Gel/PVA and n-HA/Gel/PVA composite membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), water contact angle measurement and scanning electron microscopy (SEM). The mechanical properties of the composites were determined by tensile tests. The as prepared composite membranes exhibited hydrophobility, the water contact angle of composite membrane was 126.6 when its mass ratio of n-HA/Gel/PVA was 10/50/40. The tensile strength of composite membranes was greatly increased due to the introduction of n-HA, and the tensile strength was increased to 74.92 MPa when the mass ratio of n-HA/Gel/PVA was 10/50/40. SEM observation indicated that n-HA was dispersed in the membranes and a sea-island structure was formed in the n-HA/Gel/PVA composite membranes, resulting in a significant increase in tensile strength. The as-prepared n-HA/Gel/PVA composite membranes may be applied in the field of bone tissue engineering.

  12. Improved Joining of Metal Components to Composite Structures

    NASA Technical Reports Server (NTRS)

    Semmes, Edmund

    2009-01-01

    Systems requirements for complex spacecraft drive design requirements that lead to structures, components, and/or enclosures of a multi-material and multifunctional design. The varying physical properties of aluminum, tungsten, Invar, or other high-grade aerospace metals when utilized in conjunction with lightweight composites multiply system level solutions. These multi-material designs are largely dependent upon effective joining techAn improved method of joining metal components to matrix/fiber composite material structures has been invented. The method is particularly applicable to equipping such thin-wall polymer-matrix composite (PMC) structures as tanks with flanges, ceramic matrix composite (CMC) liners for high heat engine nozzles, and other metallic-to-composite attachments. The method is oriented toward new architectures and distributing mechanical loads as widely as possible in the vicinities of attachment locations to prevent excessive concentrations of stresses that could give rise to delaminations, debonds, leaks, and other failures. The method in its most basic form can be summarized as follows: A metal component is to be joined to a designated attachment area on a composite-material structure. In preparation for joining, the metal component is fabricated to include multiple studs projecting from the aforementioned face. Also in preparation for joining, holes just wide enough to accept the studs are molded into, drilled, or otherwise formed in the corresponding locations in the designated attachment area of the uncured ("wet') composite structure. The metal component is brought together with the uncured composite structure so that the studs become firmly seated in the holes, thereby causing the composite material to become intertwined with the metal component in the joining area. Alternately, it is proposed to utilize other mechanical attachment schemes whereby the uncured composite and metallic parts are joined with "z-direction" fasteners. The

  13. Enhanced electromechanical response of Ionic Polymer-Metal Composite (IPMC) actuators by various Nafion roughening levels

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Liu, Jiayu; Chen, Hualing

    2016-04-01

    Recently, Ionic polymer metal composites (IPMCs), becoming an increasingly popular material, are used as soft actuators for its inherent properties of light weight, flexibility, softness, especial efficient transformation from electrical energy to mechanical energy with large bending strain response to low activation voltage. This paper mainly focuses on the suitable conditions for surface-roughening of Nafion 117 membrane. The surfaces of Nafion membrane were pretreated and optimized by sandblasting, mainly considering the change of sandblasting time and powder size. The modified surfaces are characterized in terms of their topography from the confocal laser scanning microscope (CLSM) and SEM. Then, the detailed change in surface and interfacial electrodes and performances for IPMC actuators prepared by the roughened membranes, were measured and discussed. The results show that an optimized roughening condition with large interface area (capacitance) can effectively increases the electromechanical responses of IPMC.

  14. Performance of polymer nano composite membrane electrode assembly using Alginate as a dopant in polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Mulijani, S.

    2016-11-01

    Polymer membrane and composite polymer for membrane electrode assembly (MEAs) are synthesized and studied for usage in direct methanol fuel cell (DMFC). In this study, we prepared 3 type of MEAs, polystyrene (PS), sulfonated polystyrene (SPS) and composite polymer SPS-alginat membrane via catalyst hot pressed method. The performance and properties of prepared MEAs were evaluated and analyzed by impedance spectrometry and scanning electron microscopy (SEM). The result showed that, water up take of MEA composite polymer SPS-alginate was obtained higher than that in SPS and PS. The proton conductivity of MEA-SPS-alginate was also higher than that PS and PSS. SEM characterization revealed that the intimate contact between the carbon catalyst layers (CL) and the membranes, and the uniformly porous structure correlate positively with the MEAs prepared by hot pressed method, exhibiting high performances for DMFC.

  15. Performance of polymer nano composite membrane electrode assembly using Alginate as a dopant in polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Mulijani, S.

    2017-01-01

    Polymer membrane and composite polymer for membrane electrode assembly (MEAs) are synthesized and studied for usage in direct methanol fuel cell (DMFC). In this study, we prepared 3 type of MEAs, polystyrene (PS), sulfonated polystyrene (SPS) and composite polymer SPS-alginat membrane via catalyst hot pressed method. The performance and properties of prepared MEAs were evaluated and analyzed by impedance spectrometry and scanning electron microscopy (SEM). The result showed that, water up take of MEA composite polymer SPS-alginate was obtained higher than that in SPS and PS. The proton conductivity of MEA-SPS-alginate was also higher than that PS and PSS. SEM characterization revealed that the intimate contact between the carbon catalyst layers (CL) and the membranes, and the uniformly porous structure correlate positively with the MEAs prepared by hot pressed method, exhibiting high performances for DMFC.

  16. Palladium/Copper Alloy Composite Membranes for High Temperature Hydrogen Separation

    SciTech Connect

    J. Douglas Way; Paul M. Thoen

    2005-08-31

    This report summarizes progress made during the second year of research funding from DOE Grant DE-FG26-03NT41792 at the Colorado School of Mines. The period of performance was September 1, 2004 through August of 2005. We have reformulated our Pd plating process to minimize the presence of carbon contamination in our membranes. This has improved durability and increased permeability. We have developed techniques for plating the outside diameter of ceramic and metal substrate tubes. This configuration has numerous advantages including a 40% increase in specific surface area, the ability to assay the alloy composition non-destructively, the ability to potentially repair defects in the plated surface, and the ability to visually examine the plated surfaces. These improvements have allowed us to already meet the 2007 DOE Fossil Energy pure H{sub 2} flux target of 100 SCFH/ft{sup 2} for a hydrogen partial pressure difference of 100 psi with several Pd-Cu alloy membranes on ceramic microfilter supports. Our highest pure H{sub 2} flux on inexpensive, porous alumina support tubes at the DOE target conditions is 215 SCFH/ft{sup 2}. Progress toward meeting the other DOE Fossil Energy performance targets is also summarized. Additionally, we have adapted our membrane fabrication procedure to apply Pd and Pd alloy films to commercially available porous stainless steel substrates. Stable performance of Pd-Cu films on stainless steel substrates was demonstrated over a three week period at 400 C. Finally, we have fabricated and tested Pd-Au alloy membranes. These membranes also exceed both the 2007 and 2010 DOE pure H{sub 2} flux targets and exhibit ideal H{sub 2}/N{sub 2} selectivities of over 1000 at partial pressure difference of 100 psi.

  17. Removal of aqueous Hg(II) and Cr(VI) using phytic acid doped polyaniline/cellulose acetate composite membrane.

    PubMed

    Li, Renjie; Liu, Lifen; Yang, Fenglin

    2014-09-15

    Conductive composite membrane-phytic acid (PA) doped polyaniline (PANI)/cellulose acetate (CA) (PANI-PA/CA) was prepared in a simple and environmental-friendly method, in which aniline was blended with CA/PA solution and polymerized before the phase conversion. The resultant composite membranes were characterized by SEM, EDX, FTIR-ATR, BET and electrical resistance measurements. When used as adsorbent for Hg(II) and Cr(VI) ions, the prepared composite membrane exhibits excellent adsorption capability. The adsorption of Hg(II) and Cr(VI) follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model, with the maximum adsorption capacity reaching 280.11 and 94.34 mg g(-1), respectively. The heavy metal loaded composite membrane can be regenerated and reused after treatment with acid or alkali solution, making it a promising and practical adsorbent for Hg(II) and Cr(VI) removal. Tests with river water were also carried out, indicating good performance and application.

  18. Distribution of Fullerene Nanoparticles between Water and Solid Supported Lipid Membranes: Thermodynamics and Effects of Membrane Composition on Distribution.

    PubMed

    Ha, Yeonjeong; Katz, Lynn E; Liljestrand, Howard M

    2015-12-15

    The distribution coefficient (Klipw) of fullerene between solid supported lipid membranes (SSLMs) and water was examined using different lipid membrane compositions. Klipw of fullerene was significantly higher with a cationic lipid membrane compared to that with a zwitterionic or anionic lipid membrane, potentially due to the strong interactions between negative fullerene dispersions and positive lipid head groups. The higher Klipw for fullerene distribution to ternary lipid mixture membranes was attributed to an increase in the interfacial surface area of the lipid membrane resulting from phase separation. These results imply that lipid composition can be a critical factor that affects bioconcentration of fullerene. Distribution of fullerene into zwitterionic unsaturated lipid membranes was dominated by the entropy contribution (ΔS) and the process was endothermic (ΔH > 0). This result contrasts the partitioning thermodynamics of highly and moderately hydrophobic chemicals indicating that the lipid-water distribution mechanism of fullerene may be different from that of molecular level chemicals. Potential mechanisms for the distribution of fullerene that may explain these differences include adsorption on the lipid membrane surfaces and partitioning into the center of lipid membranes (i.e., absorption).

  19. Reduced graphene oxide-metal/metal oxide composites: facile synthesis and application in water purification.

    PubMed

    Sreeprasad, T S; Maliyekkal, Shihabudheen M; Lisha, K P; Pradeep, T

    2011-02-15

    This paper describes a versatile, and simple synthetic route for the preparation of a range of reduced graphene oxide (RGO)-metal/metal oxide composites and their application in water purification. The inherent reduction ability of RGO has been utilized to produce the composite structure from the respective precursor ions. Various spectroscopic and microscopic techniques were employed to characterize the as-synthesized composites. The data reveal that the RGO-composites are formed through a redox-like reaction between RGO and the metal precursor. RGO is progressively oxidized primarily to graphene oxide (GO) and the formed metal nanoparticles are anchored onto the carbon sheets. Metal ion scavenging applications of RGO-MnO(2) and RGO-Ag were demonstrated by taking Hg(II) as the model pollutant. RGO and the composites give a high distribution coefficient (K(d)), greater than 10 L g(-1) for Hg(II) uptake. The K(d) values for the composites are found to be about an order of magnitude higher compared to parent RGO and GO for this application. A methodology was developed to immobilize RGO-composites on river sand (RS) using chitosan as the binder. The as-supported composites are found to be efficient adsorbent candidates for field application.

  20. Dynamic Loading Characteristics in Metals and Composites

    DTIC Science & Technology

    2009-12-01

    and appreciated. While the static strengths of composite materials , for example, have been considerably explored and documented, fewer studies have...yield of the woven laminates varied linearly with the strain rate. As noted by Taniguchi et al. [13], most composite materials displayed strain rate...EXPERIMENTAL SETUP AND PROCEDURES The material of the specimens tested is aluminum alloy AA3003-H14. The dimensions of the specimens are given in

  1. Facile Fabrication of Composite Membranes with Dual Thermo- and pH-Responsive Characteristics.

    PubMed

    Ma, Bing; Ju, Xiao-Jie; Luo, Feng; Liu, Yu-Qiong; Wang, Yuan; Liu, Zhuang; Wang, Wei; Xie, Rui; Chu, Liang-Yin

    2017-04-11

    Facile fabrication of novel functional membranes with excellent dual thermo- and pH-responsive characteristics has been achieved by simply designing dual-layer composite membranes. pH-Responsive poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers and polystyrene blended with thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) nanogels are respectively used to construct the top layer and bottom layer of composite membranes. The stretching/coiling conformation changes of the P4VP chains around the pKa (~3.5-4.5) provide the composite membranes with extraordinary pH-responsive characteristics, and the volume phase transitions of PNIPAM nanogels at the pore/matrix interfaces in the bottom layer around the volume phase transition temperature (VPTT, ~33 oC) provide the composite membranes with great thermo-responsive characteristics. The microstructures, permeability performances and dual stimuli-responsive characteristics can be well tuned by adjusting the content of PNIPAM nanogels and the thickness of the PS-b-P4VP top layer. The water fluxes of the composite membranes can be changed in order of magnitude by changing the environment temperature and pH, and the dual thermo- and pH-responsive permeation performances of the composite membranes are satisfactorily reversible and reproducible. The membrane fabrication strategy in this work provides valuable guidance for further development of dual stimuli-responsive membranes or even multi stimuli-responsive membranes.

  2. Metal Ion Speciation and Dissolved Organic Matter Composition in Soil Solutions

    NASA Astrophysics Data System (ADS)

    Benedetti, M. F.; Ren, Z. L.; Bravin, M.; Tella, M.; Dai, J.

    2014-12-01

    Knowledge of the speciation of heavy metals and the role of dissolved organic matter (DOM) in soil solution is a key to understand metal mobility and ecotoxicity. In this study, soil column-Donnan membrane technique (SC-DMT) was used to measure metal speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources and concentrations. DOM composition in these soil solutions was also determined. Our results show that in soil solution Pb and Cu are dominant in complex form, whereas Cd, Ni and Zn mainly exist as free ions; for the whole range of soil solutions, only 26.2% of DOM is reactive and consists mainly of fulvic acid (FA). The metal speciation measured by SC-DMT was compared to the predicted ones obtained via the NICA-Donnan model using the measured FA concentrations. The free ion concentrations predicted by speciation modelling were in good agreement with the measurements. Diffusive gradients in thin-films gels (DGT) were also performed to quantify the labile metal species in the fluxes from solid phase to solution in fourteen soils. The concentrations of metal species detected by DGT were compared with the free ion concentrations measured by DMT and the maximum concentrations calculated based on the predicted metal speciation in SC-DMT soil solutions. It is concluded that both inorganic species and a fraction of FA bound species account for the amount of labile metals measured by DGT, consistent with the dynamic features of this technique. The comparisons between measurements using analytical techniques and mechanistic model predictions provided mutual validation in their performance. Moreover, we show that to make accurate modelling of metal speciation in soil solutions, the knowledge of DOM composition is the crucial information, especially for Cu; like in previous studies the modelling of Pb speciation is not optimal and an updated of Pb generic binding parameters is required to reduce model prediction uncertainties.

  3. A flow-cytometry method for analyzing the composition of membrane rafts.

    PubMed

    Morales-García, M Guadalupe; Fournié, Jean-Jacques; Moreno-Altamirano, M Maximina Bertha; Rodríguez-Luna, Gabriela; Flores, Ricardo-Mondragón; Sánchez-García, F Javier

    2008-10-01

    Membrane rafts are involved in a broad variety of biological processes. Their protein composition under growth factor stimulation, anti-inflammatory or proinflammatory microenvironments, or in the course of pathogenic infections still remains to be determined. However, current techniques aimed at the identification of particular proteins on membrane rafts are not devoid of pitfalls. Membrane rafts were obtained by detergent-free based differential centrifugation from Jurkat T cells and J774 macrophages. Membrane rafts were labeled with fluorochrome-labeled antibodies directed against different cell membrane molecules, and with fluorochrome-labeled cholera toxin B that targets GM1 and analyzed by flow cytometry. CD3, CD11a, and GM1 were shown to be differentially expressed on Jurkat T cell-derived membrane rafts, indicating heterogeneity in membrane rafts composition. On the other hand, it was shown in J774 cell-derived membrane rafts that most but not all CD14 is present in the GM1-containing membrane fragments, thus confirming the heterogeneity of membrane rafts composition in other cell lines. The method described here allows the fluorometric assessment of the relative expression of more than one membrane raft component at a time, and at a single vesicle level in a fast and sensitive manner. This method seems to be a suitable approach to evaluate the molecular heterogeneity in membrane rafts composition.

  4. Effect of surface modification of microfiltration membrane on capture of toxic heavy metal ions.

    PubMed

    Madaeni, Sayed Siavash; Heidary, Farhad

    2012-01-01

    A novel complexing membrane containing 8-hydroxyquinoline groups was used for the removal of heavy metal ions (Cd2+ and Ni2+) from aqueous solution. The functionalized membranes were characterized by FTIR-ATR, SEM and EDAX for the presence of functional groups, the physical structure of the membranes and the analysis of the particles deposited on the membrane, respectively. The influence of 8-hydroxyquinoline concentration, feed concentration, pH and temperature of the solution on capture capability was studied. The modified membrane showed a higher affinity to Cd2+ cations than to Ni2+. The metal ion rejection was increased with an increase in concentration of 8-hydroxyquinoline from 0.5 to 2.0 wt%. However at a ligand concentration higher than 2.0 wt%, no significant change was observed in the metal rejection. The experimental results revealed that the metal rejection was decreased with an increase in metal ion concentration in the feed. Moreover the rejection depended on feed pH and is higher for elevated pH. By changing the temperature in the range of 23-28 degrees C, no considerable effect on metal rejection was observed. However, a higher temperature resulted in a decline in metal rejection. For filtration of a mixture of the two metal ions, the retention was similar to that of the single cations, i.e. Cd > Ni but with smaller absolute rejections.

  5. Transition metal ion FRET to measure short-range distances at the intracellular surface of the plasma membrane

    PubMed Central

    Senning, Eric N.; Aman, Teresa K.

    2016-01-01

    Biological membranes are complex assemblies of lipids and proteins that serve as platforms for cell signaling. We have developed a novel method for measuring the structure and dynamics of the membrane based on fluorescence resonance energy transfer (FRET). The method marries four technologies: (1) unroofing cells to isolate and access the cytoplasmic leaflet of the plasma membrane; (2) patch-clamp fluorometry (PCF) to measure currents and fluorescence simultaneously from a membrane patch; (3) a synthetic lipid with a metal-chelating head group to decorate the membrane with metal-binding sites; and (4) transition metal ion FRET (tmFRET) to measure short distances between a fluorescent probe and a transition metal ion on the membrane. We applied this method to measure the density and affinity of native and introduced metal-binding sites in the membrane. These experiments pave the way for measuring structural rearrangements of membrane proteins relative to the membrane. PMID:26755772

  6. Gel bead composition for metal adsorption

    SciTech Connect

    Scott, Charles D.; Woodward, Charlene A.; Byers, Charles H.

    1990-01-01

    The invention is a gel bead comprising propylene glycol alginate and bone gelatin and is capable of removing metals such as Sr and Cs from solution without adding other adsorbents. The invention could have application to the nuclear industry's waste removal activities.

  7. Gel bead composition for metal adsorption

    DOEpatents

    Scott, Charles D.; Woodward, Charlene A.; Byers, Charles H.

    1991-01-01

    The invention is a gel bead comprising propylene glycol alginate and bone gelatin and is capable of removing metals such as Sr and Cs from solution without adding other adsorbents. The invention could have application to the nuclear industry's waste removal activities.

  8. Determining eutectic composition in metal alloys

    NASA Technical Reports Server (NTRS)

    Ashbrook, R. L.; Kim, Y. G.

    1977-01-01

    Tube crucible and furnace are used to separate eutectic mixture from trial-melt ingot. As ingot is a slowly heated to melting point, initial surface meeting will be eutectic mixture. Molten metal is collected at bottom of crucible, where it is solidified.

  9. Thermally Conductive Metal-Tube/Carbon-Composite Joints

    NASA Technical Reports Server (NTRS)

    Copeland, Robert J.

    2004-01-01

    An improved method of fabricating joints between metal and carbon-fiber-based composite materials in lightweight radiators and heat sinks has been devised. Carbon-fiber-based composite materials have been used in such heat-transfer devices because they offer a combination of high thermal conductivity and low mass density. Metal tubes are typically used to carry heat-transfer fluids to and from such heat-transfer devices. The present fabrication method helps to ensure that the joints between the metal tubes and the composite-material parts in such heat-transfer devices have both (1) the relatively high thermal conductances needed for efficient transfer of heat and (2) the flexibility needed to accommodate differences among thermal expansions of dissimilar materials in operation over wide temperature ranges. Techniques used previously to join metal tubes with carbon-fiber-based composite parts have included press fitting and bonding with epoxy. Both of these prior techniques have been found to yield joints characterized by relatively high thermal resistances. The present method involves the use of a solder (63 percent Sn, 37 percent Pb) to form a highly thermally conductive joint between a metal tube and a carbon-fiber-based composite structure. Ordinarily, the large differences among the coefficients of thermal expansion of the metal tube, solder, and carbon-fiber-based composite would cause the solder to pull away from the composite upon post-fabrication cooldown from the molten state. In the present method, the structure of the solder is modified (see figure) to enable it to deform readily to accommodate the differential thermal expansion.

  10. Single-walled metal oxide nanotubes and nanotube membranes for molecular separations

    NASA Astrophysics Data System (ADS)

    Kang, Dun-Yen

    first unambiguous demonstration of covalent modification of the interior of single-walled nanotube materials. The investigations in Chapter 4 reveal a direct (in situ) route for synthesizing organic-functionalized alumino-silicate nanotubes via the use of organosilanes with functional groups in the synthesis itself (as opposed to post-synthesis modification). This work creates a one-step route for the incorporation of functional groups at the interior of nanotubes, thus bypassing the limitations of the low functional group loading as well as additional processing steps in the post-synthesis functionalization methodology of Chapter 3. The two functionalization methods developed (post-synthesis and direct functionalization) together may enable a range of applications of nanotube materials, including separations, catalysis, and molecular capture/encapsulation/storage. The direction of the work then turned to the fabrication of nanotube-containing membranes. In view of the absence of a good predictive model for the performance of nanotube-containing membranes, Chapter 5 describes the development of analytical models for quantitatively predicting the separation properties of composite membranes containing (nano)tubular fillers. These models provide useful guidance for evaluating/optimizing existing nanotube-based membranes as well as preparing nanotube-based membranes with novel device architectures and enhanced separation performance. In Chapter 6, the fabrication and characterization of free-standing nanotube/ polymer composite membranes with good organic-inorganic interface adhesion and good nanotube dispersion is discussed. A detailed investigation of the structure and propreties of these membranes (at nano-, micro-, and macro- length scales) is presented. It is shown that hese nanocomposite membranes could be effectively used to construct scalable membrane separation devices. This work is the first demonstration of a defect-free membrane containing well

  11. The assessment of metal fiber reinforced polymeric composites

    NASA Technical Reports Server (NTRS)

    Chung, Wenchiang R.

    1990-01-01

    Because of their low cost, excellent electrical conductivity, high specific strength (strength/density), and high specific modulus (modulus/density) short metal fiber reinforced composites have enjoyed a widespread use in many critical applications such as automotive industry, aircraft manufacturing, national defense, and space technology. However, little data has been found in the study of short metal fibrous composites. Optimum fiber concentration in a resin matrix and fiber aspect ratio (length-to-diameter ratio) are often not available to a user. Stress concentration at short fiber ends is the other concern when the composite is applied to a load-bearing application. Fracture in such composites where the damage will be initiated or accumulated is usually difficult to be determined. An experimental investigation is therefore carefully designed and undertaken to systematically evaluate the mechanical properties as well as electrical properties. Inconel 601 (nickel based) metal fiber with a diameter of eight microns is used to reinforce commercially available thermoset polyester resin. Mechanical testing such as tensile, impact, and flexure tests along with electrical conductivity measurements is conducted to study the feasibility of using such composites. The advantages and limitations of applying chopped metal fiber reinforced polymeric composites are also discussed.

  12. Studies on the optimization of deformation processed metal metal matrix composites

    SciTech Connect

    Ellis, Tim W.

    1994-01-04

    A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New and novel alloying procedures were investigated to extend the range of production methods available for these material. These studies focused on the use of High Pressure Gas Atomization and the development of new containment technologies for the liquid alloy. This allowed the production of alloys with a much more refined starting microstructure and lower contamination than available by other methods. The knowledge gained in the previous studies was used to develop two completely new families of deformation processed metal metal matrix composites. These composites are based on immissible alloys with yttrium and magnesium matrices and refractory metal reinforcement. This work extends the physical property range available in deformation processed metal metal matrix composites. Additionally, it also represents new ways to apply these metals in engineering applications.

  13. High temperature metal matrix composites for future aerospace systems

    NASA Technical Reports Server (NTRS)

    Stephens, Joseph R.

    1988-01-01

    Research was conducted on metal matrix composites and intermetallic matrix composites to understand their behavior under anticipated future operating conditions envisioned for aerospace power and propulsion systems of the 21st century. Extremes in environmental conditions, high temperature, long operating lives, and cyclic conditions dictate that the test evaluations not only include laboratory testing, but simulated flight conditions. The various processing techniques employed to fabricate composites are discussed along with the basic research underway to understand the behavior of high temperature composites, and the relationship of this research to future aerospace systems.

  14. High temperature metal matrix composites for future aerospace systems

    NASA Technical Reports Server (NTRS)

    Stephens, Joseph R.

    1987-01-01

    Research was conducted on metal matrix composites and intermetallic matrix composites to understand their behavior under anticipated future operating conditions envisioned for aerospace power and propulsion systems of the 21st century. Extremes in environmental conditions, high temperature, long operating lives, and cyclic conditions dictate that the test evaluations not only include laboratory testing, but simulated flight conditions. The various processing techniques employed to fabricate composites are discussed along with the basic research underway to understand the behavior of high temperature composites, and the relationship of this research to future aerospace systems.

  15. Methods of making metallic glass foil laminate composites

    DOEpatents

    Vianco, P.T.; Fisher, R.W.; Hosking, F.M.; Zanner, F.J.

    1996-08-20

    A process for the fabrication of a rapidly solidified foil laminate composite. An amorphous metallic glass foil is flux treated and coated with solder. Before solidification of the solder the foil is collected on a take-up spool which forms the composite into a solid annular configuration. The resulting composite exhibits high strength, resiliency and favorable magnetic and electrical properties associated with amorphous materials. The composite also exhibits bonding strength between the foil layers which significantly exceeds the bulk strength of the solder alone. 6 figs.

  16. Structural Durability of Damaged Metallic Panel Repaired with Composite Patches

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C.

    1997-01-01

    Structural durability/damage tolerance characteristics of an aluminum tension specimen possessing a short crack and repaired by applying a fiber composite surface patch is investigated via computational simulation. The composite patch is made of graphite/epoxy plies with various layups. An integrated computer code that accounts for all possible failure modes is utilized for the simulation of combined fiber-composite/aluminum structural degradation under loading. Damage initiation, growth, accumulation, and propagation to structural fracture are included in the simulation. Results show the structural degradation stages due to tensile loading and illustrate the use of computational simulation for the investigation of a composite patch repaired cracked metallic panel.

  17. Methods of making metallic glass foil laminate composites

    DOEpatents

    Vianco, Paul T.; Fisher, Robert W.; Hosking, Floyd M.; Zanner, Frank J.

    1996-01-01

    A process for the fabrication of a rapidly solidified foil laminate composite. An amorphous metallic glass foil is flux treated and coated with solder. Before solidification of the solder the foil is collected on a take-up spool which forms the composite into a solid annular configuration. The resulting composite exhibits high strength, resiliency and favorable magnetic and electrical properties associated with amorphous materials. The composite also exhibits bonding strength between the foil layers which significantly exceeds the bulk strength of the solder alone.

  18. A new high-performance ionic polymer–metal composite based on Nafion/polyimide blends

    NASA Astrophysics Data System (ADS)

    Nam, Jungsoo; Hwang, Taeseon; Kim, Kwang Jin; Lee, Dong-Chan

    2017-03-01

    For the first time, we report ion-exchange membranes based on Nafion and polyimide (PI, Kapton) blends to fabricate ionic polymer–metal composites (IPMCs). Polyamic acid [PAA, poly(pyromellitic dianhydride-co-4,4‧-oxydianiline), as a precursor of PI] solution was blended with Nafion solution using physical blending method to provide PAA–Nafion blend membrane. This work demonstrates that, by simple physical blending method, the thermal and mechanical properties of Nafion can be improved while maintaining the excellent actuating performance. After thermal imidization, PAA converted into PI, resulting in PI–Nafion blend membrane. Optimum conditions to cast PAA–Nafion blends and thermal imidization have been established, and blend membranes with PI wt% of 6, 12, 18, and 30 were prepared. Fourier transform infrared spectroscopy confirmed the incorporation of PI in the Nafion matrix. Thermal decomposition unique to the PI became more noticeable as the content of PI increased, which was measured by thermogravimetric analysis. Dynamic mechanical analysis showed that the storage modulus (E‧) increased as a function of PI content while loss modulus (E″) exhibited only a minor change, which resulted in the decrease in the damping properties (tan δ). The blend membranes were fabricated into IPMCs by deposition of platinum electrode onto the membrane surface through electroless plating process. Among tested, NPI-18 IPMC actuator, which has 18 wt% of PI in Nafion, showed comparable electromechanical performance to the commercially available Nafion 117 IPMC actuator.

  19. Fabrication and characterization of a flow-through nanoporous gold nanowire/AAO composite membrane

    NASA Astrophysics Data System (ADS)

    Liu, L.; Lee, W.; Huang, Z.; Scholz, R.; Gösele, U.

    2008-08-01

    The fabrication of a composite membrane of nanoporous gold nanowires and anodic aluminum oxide (AAO) is demonstrated by the electrodeposition of Au-Ag alloy nanowires into an AAO membrane, followed by selective etching of silver from the alloy nanowires. This composite membrane is advantageous for flow-through type catalytic reactions. The morphology evolution of the nanoporous gold nanowires as a function of the diameter of the Au-Ag nanowire 'precursors' is also investigated.

  20. High-Performance Metal/Carbide Composites with Far-From-Equilibrium Compositions and Controlled Microstructures

    PubMed Central

    Hu, Liangfa; O’Neil, Morgan; Erturun, Veysel; Benitez, Rogelio; Proust, Gwénaëlle; Karaman, Ibrahim; Radovic, Miladin

    2016-01-01

    The prospect of extending existing metal-ceramic composites to those with the compositions that are far from thermodynamic equilibrium is examined. A current and pressure-assisted, rapid infiltration is proposed to fabricate composites, consisting of reactive metallic and ceramic phases with controlled microstructure and tunable properties. An aluminum (Al) alloy/Ti2AlC composite is selected as an example of the far-from-equilibrium systems to fabricate, because Ti2AlC exists only in a narrow region of the Ti-Al-C phase diagram and readily reacts with Al. This kind of reactive systems challenges conventional methods for successfully processing corresponding metal-ceramic composites. Al alloy/Ti2AlC composites with controlled microstructures, various volume ratios of constituents (40/60 and 27/73) and metallic phase sizes (42–83 μm, 77–276 μm, and 167–545 μm), are obtained using the Ti2AlC foams with different pore structures as preforms for molten metal (Al alloy) infiltration. The resulting composites are lightweight and display exceptional mechanical properties at both ambient and elevated temperatures. These structures achieve a compressive strength that is 10 times higher than the yield strength of the corresponding peak-aged Al alloy at ambient temperature and 14 times higher at 400 °C. Possible strengthening mechanisms are described, and further strategies for improving properties of those composites are proposed. PMID:27752106

  1. High-Performance Metal/Carbide Composites with Far-From-Equilibrium Compositions and Controlled Microstructures

    NASA Astrophysics Data System (ADS)

    Hu, Liangfa; O’Neil, Morgan; Erturun, Veysel; Benitez, Rogelio; Proust, Gwénaëlle; Karaman, Ibrahim; Radovic, Miladin

    2016-10-01

    The prospect of extending existing metal-ceramic composites to those with the compositions that are far from thermodynamic equilibrium is examined. A current and pressure-assisted, rapid infiltration is proposed to fabricate composites, consisting of reactive metallic and ceramic phases with controlled microstructure and tunable properties. An aluminum (Al) alloy/Ti2AlC composite is selected as an example of the far-from-equilibrium systems to fabricate, because Ti2AlC exists only in a narrow region of the Ti-Al-C phase diagram and readily reacts with Al. This kind of reactive systems challenges conventional methods for successfully processing corresponding metal-ceramic composites. Al alloy/Ti2AlC composites with controlled microstructures, various volume ratios of constituents (40/60 and 27/73) and metallic phase sizes (42–83 μm, 77–276 μm, and 167–545 μm), are obtained using the Ti2AlC foams with different pore structures as preforms for molten metal (Al alloy) infiltration. The resulting composites are lightweight and display exceptional mechanical properties at both ambient and elevated temperatures. These structures achieve a compressive strength that is 10 times higher than the yield strength of the corresponding peak-aged Al alloy at ambient temperature and 14 times higher at 400 °C. Possible strengthening mechanisms are described, and further strategies for improving properties of those composites are proposed.

  2. Fabrication and EM shielding properties of electrospining PANi/MWCNT/PEO fibrous membrane and its composite

    NASA Astrophysics Data System (ADS)

    Zhang, Zhichun; Jiang, Xueyong; Liu, Yanju; Leng, Jinsong

    2012-04-01

    In this paper, Polyaniline-based fibrous membranes were fabricated with multi-walled carbon nanotubes and polyethylene oxide (PEO) by the electrospinning method. And then PANi/PEO/MWCNT fibrous membranes reinforced epoxy based nanocomposite was then fabricated. The morphology and electrical properties of PANi /MWCNT /PEO fibrous membrane was characterized by scanning electron microscope (SEM). The morphologies of the membranes indicate that the electrospining method can fabricate well nano structures fibrous membrane. The EM properties of the composite reinforced with the electrospining fibrous membrane were measured by vector network analyzer. The results show that the permittivity real, image parts and permeability real part of the composite increase by filling with PANI/PEO and PANI/CNT/PEO membrane. The EM shielding and absorb performance is base on the dielectric dissipation. And different membranes made of different materials show different EM parameter, and different EM shielding performance, which can be used to the EM shielding and stealth material design and fabrication.

  3. A polytetrafluoroethylene porous membrane and dimethylhexadecylamine quaternized poly (vinyl benzyl chloride) composite membrane for intermediate temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Cao, Yuan-Cheng; Xu, Chenxi; Zou, Linling; Scott, Keith; Liu, Jiyan

    2015-10-01

    A composite material for phosphoric acid (PA) loaded membrane was prepared using a porous polytetrafluoroethylene (PTFE) thin film. N, N-Dimethylhexadecylamine partially quaternized poly (vinyl benzyl chloride) (qPVBzCl-) was synthesized as the substrate for the phosphoric acid loaded polymer membrane. SEM observation indicated that the pores were filled with the qPVBzCl-. The maximum PA loading level was calculated to be 4.67-5.12 per repeat unit on average. TGA results showed that resultant composite membrane was stable in the intermediate temperature from 100 °C to 200 °C. The composite membrane tensile stress was 56.23 MPa, and the Young's Modulus was 0.25 GPa, and the fractured elongation was 23%. The conductivity of the composite membrane after the PA addition (H3PO4@PTFE/qPVBzCl-) increased from 0.085 S cm-1 to 0.11 S cm-1 from 105 °C to 180 °C. The peak power density of the H2/O2 at 175 °C under low humidity condition (<1%) for H3PO4@PTFE/qPVBzCl- membranes was 360 mW cm-2.

  4. Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

    NASA Astrophysics Data System (ADS)

    Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

    2016-01-01

    In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

  5. Polypeptide and phospholipid composition of the membrane of rat liver peroxisomes: comparison with endoplasmic reticulum and mitochondrial membranes

    PubMed Central

    1982-01-01

    Membranes were isolated from highly purified peroxisomes, mitochondria, and rough and smooth microsomes of rat liver by the one-step Na2CO3 procedure described in the accompanying paper (1982, J. Cell Biol. 93:97-102). The polypeptide compositions of these membranes were determined by SDS PAGE and found to be greatly dissimilar. The peroxisomal membrane contains 12% of the peroxisomal protein and consists of three major polypeptides (21,700, 67,700 and 69,700 daltons) as well as some minor polypeptides. The major peroxisomal membrane proteins as well as most of the minor ones are absent from the endoplasmic reticulum (ER). Conversely, most ER proteins are absent from peroxisomes. By electron microscopy, purified peroxisomal membranes are approximately 6.8 nm thick and have a typical trilaminar appearance. The phospholipid/protein ratio of peroxisomal membranes is approximately 200 nmol/mg; the principal phospholipids are phosphatidyl choline and phosphatidyl ethanolamine as in ER and mitochondrial membranes. In contrast to the mitochondria, peroxisomal membranes contain no cardiolipin. All the membranes investigated contain a polypeptide band with a molecular mass of approximately 15,000 daltons. Whether this represents an exceptional common membrane protein or a coincidence is unknown. The implications of these results for the biogenesis of peroxisomes are discussed. PMID:7068748

  6. Poly(vinyl alcohol)/poly(vinyl chloride) composite polymer membranes for secondary zinc electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Yang, Jen Ming; Wu, Cheng-Yeou

    A microporous composite polymer membrane composed of poly(vinyl alcohol) (PVA) and poly(vinyl chloride) (PVC), was prepared by a solution casting method and a partial dissolution process. The characteristic properties of microporous PVA/PVC composite polymer membranes containing 2.5-10 wt.% PVC polymers as fillers were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), capillary flow porometry (CFP), micro-Raman spectroscopy, dynamic mechanical analyzer (DMA) and the AC impedance method. The electrochemical properties of a secondary Zn electrode with the PVA/PVC composite polymer membrane were studied using the galvanostatic charge/discharge method. The PVA/PVC composite polymer membrane showed good thermal, mechanical and electrochemical properties. As a result, the PVA/PVC composite polymer membrane appears to be a good candidate for use on the secondary Zn electrodes.

  7. Hybrid membranes of metal-organic molecule nanocages for aromatic/aliphatic hydrocarbon separation by pervaporation.

    PubMed

    Zhao, Cui; Wang, Naixin; Wang, Lin; Huang, Hongliang; Zhang, Rong; Yang, Fan; Xie, Yabo; Ji, Shulan; Li, Jian-Rong

    2014-11-21

    Hybrid membranes composed of porous metal-organic molecule nanocages as fillers embedded in a hyperbranched polymer (Boltorn W3000) were fabricated, which exhibit excellent pervaporation separation performances towards aromatic/aliphatic hydrocarbons. The unique nature of the molecule-based fillers and their good dispersion and compatibility in/with the polymer are responsible for the good membrane properties.

  8. High-speed pectic enzyme fractionation by immobilised metal ion affinity membranes.

    PubMed

    Camperi, S A; Grasselli, M; Cascone, O

    2000-01-01

    Immobilised metal ion affinity polysulfone hollow-fibre membranes, with a high capacity for protein adsorption, were prepared and their utilisation for commercial pectic enzyme fractionation was studied. The pass-through fraction containing pectinlyase is useful for fruit-juice clarification without methanol production on account of pectinesterase being retained by the IDA-Cu2+ membrane.

  9. Metal matrix coated fiber composites and the methods of manufacturing such composites

    DOEpatents

    Weeks, Jr., Joseph K.; Gensse, Chantal

    1993-01-01

    A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials.

  10. Porous metal hydride composite and preparation and uses thereof

    DOEpatents

    Steyert, William A.; Olsen, Clayton E.

    1982-01-01

    A composite formed from large pieces of aggregate formed from (1) metal hydride (or hydride-former) powder and (2) either metal powder or plastic powder or both is prepared. The composite has large macroscopic interconnected pores (much larger than the sizes of the powders which are used) and will have a very fast heat transfer rate and low windage loss. It will be useful, for example, in heat engines, hydrogen storage devices, and refrigerator components which depend for their utility upon both a fast rate of hydriding and dehydriding. Additionally, a method of preparing the composite and a method of increasing the rates of hydriding and dehydriding of metal hydrides are also given.

  11. Porous metal hydride composite and preparation and uses thereof

    DOEpatents

    Steyert, W.A.; Olsen, C.E.

    1980-03-12

    A composite formed from large pieces of aggregate formed from (1) metal hydride (or hydride-former) powder and (2) either metal powder or plastic powder or both is prepared. The composite has large macroscopic interconnected pores (much larger than the sizes of the powders which are used) and will have a very fast heat transfer rate and low windage loss. It will be useful, for example, in heat engines, hydrogen storage devices, and refrigerator components which depend for their utility upon both a fast rate of hydriding and dehydriding. Additionally, a method of preparing the composite and a method of increasing the rates of hydriding and dehydriding of metal hydrides are also given.

  12. Preparation and performance of novel thermally stable polyamide/PPENK composite nanofiltration membranes

    NASA Astrophysics Data System (ADS)

    Hu, Lijie; Zhang, Shouhai; Han, Runlin; Jian, Xigao

    2012-09-01

    Novel thermally stable composite nanofiltration (NF) membranes were prepared from piperazine (PIP) and trimesoyl chloride (TMC) on poly (phthalazione ether nitrile ketone) (PPENK) ultrafiltration (UF) membranes by interfacial polymerization. The effects of monomers concentration, reaction time and organic solvents on the performance of composite membranes were investigated. The effects of operating pressure and the salt solution concentration on the performance of composite membranes were also discussed. The different salts rejection of PPENK composite membranes decreased in the order of Na2SO4 > MgSO4 > Al2(SO4)3 > NaCl > MgCl2, which indicated a negative charge at the membrane surface. The flux and Na2SO4 rejection of PPENK composite membranes reached 57.9 L/m2 h and 98.4% under the optimized conditions and operating pressure of 1.0 MPa. Furthermore, the morphology and chemical structure of membranes were examined by scanning electronic microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. Moreover, the thermal stability of PPENK NF membranes was also investigated. When temperature of the feed solution raised from 20 °C to 80 °C, the permeation flux increased about four times without significant change of rejection. The flux increased first then reached a plateau and the rejection kept constant when PPENK NF membranes in boiling de-ionized water were boiled to 3 h.

  13. Nanocellulose based asymmetric composite membrane for the multiple functions in cell encapsulation.

    PubMed

    Park, Minsung; Shin, Sungchul; Cheng, Jie; Hyun, Jinho

    2017-02-20

    We describe the nanocomposite membrane for cell encapsulation using nanocelluose hydrogels. One of the surfaces of bacterial cellulose (BC) pellicles was coated with collagen to enhance cell adhesion and the opposite side of the BC pellicles was coated with alginate to protect transplanted cells from immune rejection by the reduced pore size of the composite membrane. The morphology of nanocomposite membrane was observed by scanning electron microscopy and the permeability of the membrane was estimated by the release test using different molecular weights of polymer solution. The nanocomposite membrane was permeable to small molecules but impermeable to large molecules such as IgG antibodies inferring the potential use in cell implantation. In addition, the BC-based nanocomposite membrane showed a superior mechanical property due to the incorporation of compared with alginate membranes. The cells attached efficiently to the surface of BC composite membranes with a high level of cell viability as well as bioactivity. Cells grown on the BC composite membrane kit released dopamine freely to the medium through the membrane, which showed that the BC composite membrane would be a promising cell encapsulation material in implantation.

  14. Anisotropic Damage Mechanics Modeling in Metal Matrix Composites

    DTIC Science & Technology

    1993-05-15

    conducted on a titanium aluminide SiC-reinforced metal matrix composite. Center-cracked plates with laminate layups of (0/90) and (±45). were tested...Kattan, P. I., "Finite Strain Plasticity and Damage in Constitutive Modeling of Metals with Spin Tensors," Applied Mechanics Reviews, Vol. 45, No. 3...34Contractors Meeting on Mechanics of Materials," Dayton, Ohio, October 1991. Voyiadjis, G. Z., and Kattan, P. I., "Finite Strain Plasticity and Damage in

  15. Pallasites - Metal composition, classification and relationships with iron meteorites

    NASA Technical Reports Server (NTRS)

    Scott, E. R. D.

    1977-01-01

    A comparative study was conducted of the metal composition of 34 pallasites in order to shed further light on the origin of these meteorites. Concentrations of Au, As, Co, Ga, Ge, Ir, Ni, and W in pallasitic metal were determined. Most pallasites are found to have similar compositions indicating a close genetic relationship, and are designated as main group. The Eagle Station Trio is unrelated to the main group as indicated by higher Ni, Ge, and Ir and lower As, Au, and Ga contents in the metal, and olivine richer in Fe and Sc and poorer in Mg and Mn. The trio of Springwater, Rawlinna and Phillips County have metal compositions appropriate to high-Ni main group members, but their fayalite contents suggest they are not closely related to it. Pavlodar and Glorieta Mountain appear to be unique pallasites, and Brenham an anomalous main group member. Krasnoyarsk is classified as a main group member. Main group pallasites have metal compositions which overlap those of IIIAB iron meteorites on a Ga-Ge plot, and they have similar Au, As, Cr, Ir, Ni and W contents to high-Ni IIIAB irons.

  16. Composite yarns of multiwalled carbon nanotubes with metallic electrical conductivity.

    PubMed

    Randeniya, Lakshman K; Bendavid, Avi; Martin, Philip J; Tran, Canh-Dung

    2010-08-16

    Unique macrostructures known as spun carbon-nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room-temperature conductivities of about 5 x 10(2) S cm(-1). Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal-CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self-fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu-CNT and Au-CNT composite yarns prepared by this method have metal-like electrical conductivities (2-3 x 10(5) S cm(-1)) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30-50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications.

  17. Hydrogen transport membranes

    DOEpatents

    Mundschau, Michael V.

    2005-05-31

    Composite hydrogen transport membranes, which are used for extraction of hydrogen from gas mixtures are provided. Methods are described for supporting metals and metal alloys which have high hydrogen permeability, but which are either too thin to be self supporting, too weak to resist differential pressures across the membrane, or which become embrittled by hydrogen. Support materials are chosen to be lattice matched to the metals and metal alloys. Preferred metals with high permeability for hydrogen include vanadium, niobium, tantalum, zirconium, palladium, and alloys thereof. Hydrogen-permeable membranes include those in which the pores of a porous support matrix are blocked by hydrogen-permeable metals and metal alloys, those in which the pores of a porous metal matrix are blocked with materials which make the membrane impervious to gases other than hydrogen, and cermets fabricated by sintering powders of metals with powders of lattice-matched ceramic.

  18. Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.

    SciTech Connect

    Pratt, Joseph William; Cordaro, Joseph Gabriel; Sartor, George B.; Dedrick, Daniel E.; Reeder, Craig L.

    2012-02-01

    In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. Acknowledgements The authors would like to thank the following people who participated in this project: Ned Stetson (U.S. Department of Energy) for sponsorship and support of the project. Ken Stewart (Sandia) for building the flow-through calorimeter and cycling test stations. Isidro Ruvalcaba, Jr. (Sandia) for qualitative experiments on the interaction of sodium alanate with water. Terry Johnson (Sandia) for sharing his expertise and knowledge of metal hydrides, and sodium alanate in particular. Marcina Moreno (Sandia) for programmatic assistance. John Khalil (United Technologies Research Corp) for insight into the hazards of reactive metal hydrides and real-world accident scenario experiments. Summary In an attempt to mitigate and/or manage hazards associated with storing bulk quantities of reactive metal hydrides, polymer composite materials (a mixture of a mitigating polymer and a metal hydride) were synthesized and tested

  19. Membrane filtration technology for the metals fabrication industry

    SciTech Connect

    Peden, J.; Lindsey, T.

    1995-12-31

    Membrane filtration for separating contaminants from aqueous cleaning solutions based on molecular size, shape, and charge is described in this paper. Ultrafiltration is a pressure driven membrane filtration technique capable of producing high quality filtrate from wastewater. Three case studies are briefly described where ultrafiltration has been incorporated into the manufacturing process.

  20. Testing composite-to-metal tubular lap joints

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.; Slavin, A.M.

    1993-11-01

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  1. Fiber shape effects on metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Brown, H. C.; Lee, H.-J.

    1992-01-01

    The effects of different fiber shapes on the behavior of metal matrix composites is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers in a three by three unit cell array of a SiC/Ti-15-3 metal matrix composite is used in the analysis. The model is employed to represent five fiber shapes that include a circle, an ellipse, a kidney, and two different cross shapes. The distribution of stresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis using the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes. In general, fiber dominated properties are not affected by fiber geometry and matrix dominated properties are only moderately affected.

  2. Dry sliding wear of heat treated hybrid metal matrix composites

    NASA Astrophysics Data System (ADS)

    Naveed, Mohammed; Khan, A. R. Anwar

    2016-09-01

    In recent years, there has been an ever-increasing demand for enhancing mechanical properties of Aluminum Matrix Composites (AMCs), which are finding wide applications in the field of aerospace, automobile, defence etc,. Among all available aluminium alloys, Al6061 is extensively used owing to its excellent wear resistance and ease of processing. Newer techniques of improving the hardness and wear resistance of Al6061 by dispersing an appropriate mixture of hard ceramic powder and whiskers in the aluminium alloy are gaining popularity. The conventional aluminium based composites possess only one type of reinforcements. Addition of hard reinforcements such as silicon carbide, alumina, titanium carbide, improves hardness, strength and wear resistance of the composites. However, these composites possessing hard reinforcement do posses several problems during their machining operation. AMCs reinforced with particles of Gr have been reported to be possessing better wear characteristics owing to the reduced wear because of formation of a thin layer of Gr particles, which prevents metal to metal contact of the sliding surfaces. Further, heat treatment has a profound influence on mechanical properties of heat treatable aluminium alloys and its composites. For a solutionising temperature of 5500C, solutionising duration of 1hr, ageing temperature of 1750C, quenching media and ageing duration significantly alters mechanical properties of both aluminium alloy and its composites. In the light of the above, the present paper aims at developing aluminium based hybrid metal matrix composites containing both silicon carbide and graphite and characterize their mechanical properties by subjecting it to heat treatment. Results indicate that increase of graphite content increases wear resistance of hybrid composites reinforced with constant SiC reinforcement. Further heat treatment has a profound influence on the wear resistance of the matrix alloy as well as its hybrid composites

  3. Microchannel-patterned and heparin micro-contact-printed biodegradable composite membranes for tissue-engineering applications.

    PubMed

    Baran, Erkan T; Tuzlakoğlu, Kadriye; Salgado, António; Reis, Rui L

    2011-06-01

    Microchannel-patterned starch-poly(capro-lactone)/hydydroxyapatite (SPCL-HA) and starch-poly(lactic acid) (SPLA) composite membranes were produced for use as a laminated tissue-engineering scaffold that incorporates both physical and biochemical patterns. For this purpose, SPCL (30% starch) blended with inorganic hydroxyl apatite (50%) and SPLA (50% starch) membranes were made with compressive moulding. Consequently, the microchannel structures (width 102 µm, 174 µm intervals) were developed on the composite membranes by means of micro-patterned metal mould(s) and hydraulic pressing. An elastomer poly(dimetylsiloxane) stamp was used to transfer heparin as a biochemical cue over the microchannel surfaces by micro-contact printing (µCP). Toluidine blue staining of developed capillaries and heparin µCP-coated membranes showed that heparin was transferred predominantly over the microchannel surfaces. Fibroblast cell culture over the microchannel-formed and heparin µCP-modified SPCL-HA and SPLA membranes showed distinct growth patterns. In contrast to the uniform cell layer formed on unmodified microchannels, the cells were bridging across the grooves of heparin-printed microchannels. At extended culture periods, the heparin-printed microchannels were covered with a layer of fibroblast cells without cellular ingrowths inside. This study indicated that the topographical pattern could induce an organization of fibroblasts only with the biochemical cue and the cells' functions can be controlled spatially over the microchannels by using both cues.

  4. Metallic Coatings for Graphite/Epoxy Composites

    DTIC Science & Technology

    1980-08-01

    Aero Structures Dept -. Radomes Section B-2 DISTRIBUTION (cont.)K COPIES * U. S. Army Air Mobility R&D Laboratory 1II 1Fort Eustis, VA ATTN: SAVDL-EU...for graphite/epoxy laminated aircraft structures were developed to provide protection against moisture penetration, electro’)- magnetic interference...performance * aircraft. Utilization of advanced composite structures to their design limits neces- sitates the protection of these structures against

  5. Plasma spray forming metals, intermetallics, and composites

    NASA Astrophysics Data System (ADS)

    Sampath, Sanjay; Herman, Herbert

    1993-07-01

    Plasma spray processing is a droplet deposition method that combines the steps of melting, rapid solidification, and consolidation into a single step. The versatility of the technology enables the processing of freestanding bulk, near-net shapes of a wide range of alloys, intermetallics, ceramics, and composites, while still retaining the benefits of rapid solidification processing. In particular, it is possible to produce dense forms through vacuum plasma spraying.

  6. NOVEL POLY-GLUTAMIC ACID FUNCTIONALIZED MICROFILTRATION MEMBRANES FOR SORPTION OF HEAVY METALS AT HIGH CAPACITY

    EPA Science Inventory

    Various sorbent/ion exchange materials have been reported in the literature for metal ion entrapment. We have developed a highly innovative and new approach to obtain high metal pick-up utilizing poly-amino acids (poly-L-glutamic acid, 14,000 MW) covalently attached to membrane p...

  7. Measuring the composition-curvature coupling in binary lipid membranes by computer simulations

    SciTech Connect

    Barragán Vidal, I. A. Müller, M.; Rosetti, C. M.; Pastorino, C.

    2014-11-21

    The coupling between local composition fluctuations in binary lipid membranes and curvature affects the lateral membrane structure. We propose an efficient method to compute the composition-curvature coupling in molecular simulations and apply it to two coarse-grained membrane models—a minimal, implicit-solvent model and the MARTINI model. Both the weak-curvature behavior that is typical for thermal fluctuations of planar bilayer membranes as well as the strong-curvature regime corresponding to narrow cylindrical membrane tubes are studied by molecular dynamics simulation. The simulation results are analyzed by using a phenomenological model of the thermodynamics of curved, mixed bilayer membranes that accounts for the change of the monolayer area upon bending. Additionally the role of thermodynamic characteristics such as the incompatibility between the two lipid species and asymmetry of composition are investigated.

  8. Internal zone growth method for producing metal oxide metal eutectic composites

    DOEpatents

    Clark, Grady W.; Holder, John D.; Pasto, Arvid E.

    1980-01-01

    An improved method for preparing a cermet comprises preparing a compact having about 85 to 95 percent theoretical density from a mixture of metal and metal oxide powders from a system containing a eutectic composition, and inductively heating the compact in a radiofrequency field to cause the formation of an internal molten zone. The metal oxide particles in the powder mixture are effectively sized relative to the metal particles to permit direct inductive heating of the compact by radiofrequency from room temperature. Surface melting is prevented by external cooling or by effectively sizing the particles in the powder mixture.

  9. Durable hydrophobic coating composition for metallic surfaces and method for the preparation of the composition

    DOEpatents

    Liu, Jiong

    2017-02-14

    A durable hydrophobic coating composition containing fluorinated silanes for metallic surfaces, such as stainless steel surfaces. The composition includes at least one fluorine-containing silane compound, at least one phosphorus-containing silane compound, and at least one hydrolysable compound. This coating is suitable for condenser tubes, among other applications, to promote dropwise condensation.

  10. Synthesis, Annealing and Performance of Pd-Au Asymmetric Composite Membranes for Hydrogen Purification

    SciTech Connect

    Ma, Yi Hua; Chen, Chao-Huang; Catalano, Jacopo; Guazzone, Federico; Payzant, E Andrew

    2013-01-01

    Composite asymmetric Pd-Au membranes, based on porous Inconel and Hastelloy tubular supports, were prepared by means of electroless deposition and galvanic displacement techniques and tested, before and after Au deposition, in pure H2 atmosphere. The final membranes, with Au average bulk composition up to 16.7 wt%, were 9 15 m thick and showed, for the entire duration of characterization, H2/He ideal selectivity in excess of 900. The annealing of the as-prepared membranes was conducted through the coating and diffusion mechanism in He and H2 atmospheres at 500 C. The annealing conditions were chosen after non-isothermal and isothermal HT-XRD studies on coupons synthetized with similar preparation methods. After the formation of the Pd-Au layer, the membranes showed steady flux and a stable Au gradient on the membrane top layer. Comparisons between permeance for Pd/Au and pure Pd membranes indicated that the membranes with an Au average bulk composition of 4.5 and 5.4 wt% had an enhancement, up to 20%, of the H2 permeability in the temperature range 250 450 C with respect to pure Pd membranes. On the other hand, the membrane having the highest Au composition, 16.7 wt%, even though characterized by a lower H2 permeability (77% of pure Pd) had a rather high surface Au composition (approximately 46 wt%), which might provide good H2S poisoning tolerance.

  11. Preparation and characterization of phosphorylated Zr-doped hybrid silica/PSF composite membrane.

    PubMed

    Zhang, Yuqing; Jin, Zhenhua; Shan, Xing; Sunarso, Jaka; Cui, Ping

    2011-02-15

    Polysulfone (PSF) membranes are broadly applied in many fields owing to good physicochemical stability, resistance to oxidation and chlorine. But when treated with wastewater containing oil, PSF membranes are easy to be contaminated for its hydrophobicity, which can result in the declining of flux and lifespan of the membrane and limit their application in large scale. To enhance the capability of PSF membrane in the above circumstances, phosphorylated Zr-doped hybrid silica particles (SZP particles) were firstly prepared. SZP particles have various point defects inside their structure and lots of hydroxide radicals on their surface. SZP particles were added to the porous matrix of PSF to prepare a novel composite membrane (SZP/PSF) through a phase inversion process. Finally, the optimum preparation conditions of SZP/PSF composite membranes were determined. The optimum conditions are: the mass ratio of PSF, PEG400 and SZP is 12:10:10; ultrasound 10 min inside each 30 min; the pre-evaporating time is 10s. Optimized SZP/PSF composite membrane was characterized by scanning electron microscope (SEM) and ultrafiltration experiment. The results indicate that SZP particles can be uniformly dispersed in SZP/PSF composite membranes with excellent hydrophilic property, antifouling capability and tensile strength. Therefore, it can be concluded that the optimized SZP/PSF composite membrane is desirable in the treatment of wastewater containing oil and wastewater.

  12. Development of cesium phosphotungstate salt and chitosan composite membrane for direct methanol fuel cells.

    PubMed

    Xiao, Yanxin; Xiang, Yan; Xiu, Ruijie; Lu, Shanfu

    2013-10-15

    A novel composite membrane has been developed by doping cesium phosphotungstate salt (CsxH3-xPW12O40 (0≤x≤3), Csx-PTA) into chitosan (CTS/Csx-PTA) for application in direct methanol fuel cells (DMFCs). Uniform distribution of Csx-PTA nanoparticles has been achieved in the chitosan matrix. The proton conductivity of the composite membrane is significantly affected by the Csx-PTA content in the composite membrane as well as the Cs substitution in PTA. The highest proton conductivity for the CTS/Csx-PTA membranes was obtained with x=2 and Cs2-PTA content of 5 wt%. The value is 6×10(-3) S cm(-1) and 1.75×10(-2) S cm(-1) at 298 K and 353 K, respectively. The methanol permeability of CTS/Cs2-PTA membrane is about 5.6×10(-7), 90% lower than that of Nafion-212 membrane. The highest selectivity factor (φ) was obtained on CTS/Cs2-PTA-5 wt% composite membrane, 1.1×10(4)/Scm(-3)s. The present study indicates the promising potential of CTS/Csx-PTA composite membrane as alternative proton exchange membranes in direct methanol fuel cells.

  13. Zirconium oxide nanotube-Nafion composite as high performance membrane for all vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Aziz, Md. Abdul; Shanmugam, Sangaraju

    2017-01-01

    A high-performance composite membrane for vanadium redox flow battery (VRB) consisting of ZrO2 nanotubes (ZrNT) and perfluorosulfonic acid (Nafion) was fabricated. The VRB operated with a composite (Nafion-ZrNT) membrane showed the improved ion-selectivity (ratio of proton conductivity to permeability), low self-discharge rate, high discharge capacity and high energy efficiency in comparison with a pristine commercial Nafion-117 membrane. The incorporation of zirconium oxide nanotubes in the Nafion matrix exhibits high proton conductivity (95.2 mS cm-1) and high oxidative stability (99.9%). The Nafion-ZrNT composite membrane exhibited low vanadium ion permeability (3.2 × 10-9 cm2 min-1) and superior ion selectivity (2.95 × 107 S min cm-3). The VRB constructed with a Nafion-ZrNT composite membrane has lower self-discharge rate maintaining an open-circuit voltage of 1.3 V for 330 h relative to a pristine Nafion membrane (29 h). The discharge capacity of Nafion-ZrNT membrane (987 mAh) was 3.5-times higher than Nafion-117 membrane (280 mAh) after 100 charge-discharge cycles. These superior properties resulted in higher coulombic and voltage efficiencies with Nafion-ZrNT membranes compared to VRB with Nafion-117 membrane at a 40 mA cm-2 current density.

  14. Composite Nafion 117-TMSP membrane for Fe-Cr redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Haryadi, Gunawan, Y. B.; Mursid, S. P.; Harjogi, D.

    2016-04-01

    The modification of Nafion 117 - TMSP (trimethoxysylilprophanthiol) composite membrane has been conducted by in-situ sol-gel method followed by characterization of structural and properties of material using spectroscopic techniques. The performance of composite membrane has then been examined in the single stack module of Fe-Cr Redox Flow Battery. It was found that the introduction of silica from TMSP through sol-gel process within the Nafion 117 membrane produced composite membrane that has slightly higher proton conductivity values as compared to the pristine of Nafion 117 membrane observed by electrochemical impedance spectroscopy. The degree of swelling of water in the composite membrane demonstrated greatly reduced than a pristine Nafion 117 signifying low water cross over. The SEM-EDX measurements indicated that there was no phase separation occurred suggesting that silica nanoparticles are distributed homogeneously within the composite membrane. The composite membrane used as separator in the system of Fe-Cr Redox Flow Battery revealed no cross mixing (crossover) occurred between anolyte and catholyte in the system as observed from the total voltage measurements that closed to the theoretical value. The battery efficiency generally increased as the volume of the electrolytes enlarged.

  15. Characterization of the mycoplasma membrane proteins. VI. Composition and disposition of proteins in membranes from aging Mycoplasma hominis cultures.

    PubMed

    Amar, A; Rottem, S; Kahane, I; Razin, S

    1976-03-05

    Membranes of Mycoplasma hominis cells from cultures progressing from the mid to the end of the logarithmic phase of growth became richer in protein, poorer in phospholipids and cholesterol, heavier in density, and more viscous as determined by EPR. The membrane-bound ATPase activity declined steeply. Electrophoretic analysis failed to show marked changes in membrane protein composition on aging, apart from an increase in the staining intensity of one protein band (Mr approximately 130 000) concomitant with a decrease in the staining intensity of several minor protein bands of high molecular weight. To test for possible changes in the disposition of the various membrane proteins on aging of cultures, a comparison was made of the susceptibility of membrane proteins of intact cells and isolated membranes to trypsinization and lactoperoxidase-mediated iodination. The iodination values and the percent of membrane protein released by trypsinization of intact cells were similar in cells from cultures of different ages, indicating no significant changes in the organization of the proteins on the outer surface. On the other hand, trypsinization and iodination of isolated membranes were found to be most markedly affected by the culture age, indicating significant changes in the organization of the proteins on the inner membrane surface. Thus, the iodination values of isolated membranes decreased by almost two fold, while the percentage of protein released from the membrane by trypsin increased from 28% to 50% during the experimental period. It is suggested that aging in M. hominis cultures is accompanied by a continuous increase in the packing density of the protein molecules on the inner surface of the cell membrane.

  16. Contact Sensor Attachment to Titanium Metal Composites

    NASA Technical Reports Server (NTRS)

    Vargas-Aburto, Carlos

    1997-01-01

    A Pd-13wt%Cr solid solution is a promising high-temperature strain gage alloy. In bulk form it has a number of properties that are desirable in a resistance strain gage material, such as a linear electrical-resistance-versus-temperature curve to 1000 C and stable electrical resistance in air at 1000 C. However, unprotected fine wire gages fabricated from this alloy perform well only to 600 C. At higher temperatures severe oxidation degrades their electrical performance. In this work Auger electron spectroscopy has been used to study the oxidation chemistry of the alloy wires and ribbons. Results indicate that the oxidation is caused by a complex mechanism that is not yet fully understood. As expected, during oxidation, a layer of chromium oxide is formed. This layer, however, forms beneath a layer of metallic palladium. The results of this study have increased the understanding of the oxidation mechanism of Pd-13wt%Cr.

  17. Aluminum/alkaline earth metal composites and method for producing

    DOEpatents

    Russell, Alan M; Anderson, Iver E; Kim, Hyong J; Freichs, Andrew E

    2014-02-11

    A composite is provided having an electrically conducting Al matrix and elongated filaments comprising Ca and/or Sr and/or Ba disposed in the matrix and extending along a longitudinal axis of the composite. The filaments initially comprise Ca and/or Sr and/or Ba metal or allow and then may be reacted with the Al matrix to form a strengthening intermetallic compound comprising Al and Ca and/or Sr and/or Ba. The composite is useful as a long-distance, high voltage power transmission conductor.

  18. Finite element analysis of metal matrix composite blade

    NASA Astrophysics Data System (ADS)

    Isai Thamizh, R.; Velmurugan, R.; Jayagandhan, R.

    2016-10-01

    In this work, compressor rotor blade of a gas turbine engine has been analyzed for stress, maximum displacement and natural frequency using ANSYS software for determining its failure strength by simulating the actual service conditions. Static stress analysis and modal analysis have been carried out using Ti-6Al-4V alloy, which is currently used in compressor blade. The results are compared with those obtained using Ti matrix composites reinforced with SiC. The advantages of using metal matrix composites in the gas turbine compressor blades are investigated. From the analyses carried out, it seems that composite rotor blades have lesser mass, lesser tip displacement and lower maximum stress values.

  19. Fracture criteria for discontinuously reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.; Goree, J. G.; Albritton, J.; Ratnaparkhi, P.

    1988-01-01

    Summarized is the progress achieved during the period September 16, 1987 to August 15, l988 on NASA Grant NAG1-724, Fracture Criteria for Discontinuously Reinforced Metal Matrix Composites. Appended are copies of three manuscripts prepared under NASA funding during the performance period.

  20. A Study on Dynamic Properties of Composite Metal Foams

    DTIC Science & Technology

    2012-12-01

    steel hollow sphere foam ( HSF ) made by Hollomet with average cell diameter of 2.45 mm and 3 specimen dimensions 23 × 23 × 40 mm for comparison...List of Symbols, Abbreviations, and Acronyms CMF Composite Metal Foam EDS Energy Dispersive Spectroscopy HSF hollow sphere foam LVDT Linear

  1. Metal matrix composites: History, status, factors and future

    NASA Astrophysics Data System (ADS)

    Cyriac, Ajith James

    The history, status, and future of metal matrix composites are presented by evaluating the progression of available literature through time. The trends that existed and issues that still prevail are discussed and a prediction of the future for MMCs is presented. The factors that govern the performance of metal matrix composites are also discussed. In many developed countries and in several developing countries there exists continued interest in MMCs. Researchers tried numerous combinations of matrices and reinforcements since work strictly on MMCs began in the 1950s. This led to developments for aerospace and defense applications, but resultant commercial applications were limited. The introduction of ceramic whiskers as reinforcement and the development of 'in-situ' eutectics in the 1960s aided high temperature applications in aircraft engines. In the late 1970s the automobile industries started to take MMCs seriously. In the last 20 years, MMCs evolved from laboratories to a class of materials with numerous applications and commercial markets. After the collapse of the Berlin Wall, prevailing order in the world changed drastically. This effect was evident in the progression of metal matrix composites. The internet connected the world like never before and tremendous information was available for researchers around the world. Globalization and the internet resulted in the transformation of the world to a more level playing field, and this effect is evident in the nature and source of research on metal matrix composites happening around the world.

  2. Fracture criteria for discontinuously reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.; Goree, J. G.; Albritton, J.; Ratnarparkhi, P.

    1988-01-01

    The effect of sample configuration on the details of initial crack propagation in discontinuously whisker reinforced aluminum metal matrix composites was investigated. Care was taken to allow direct comparison of fracture toughness values utilizing differing sample configurations and orientations, holding all materials variables constant, e.g., extrusion ration, heat treatment, and chemistry.

  3. Surface modification of silica- and cellulose-based microfiltration membranes with functional polyamino acids for heavy metal sorption

    SciTech Connect

    Ritchie, S.M.C.; Bhattacharyya, D.; Bachas, L.G.; Olin, T.; Sikdar, S.K.

    1999-09-14

    Functionalized membranes represent a field with multiple applications. Examination of specific metal-macromolecule interactions on these surfaces presents an excellent method for characterization of these materials. These interactions may also be exploited for heavy metal sorption from drinking and industrial water sources. Various low-capacity, silica-based ion-exchange and chelating sorbents (about 0.5 mmol of metal/g or resin) are available for treatment of such waters. Cellulosic membrane-based sorbents, functionalized with polyamino acids, present an excellent approach for high-capacity (3--14 mmol of metal/g or sorbent) metal sorption. Silica-based membrane sorbents posses metal sorption capacities approaching those of cellulosic-based membranes, with the added benefits of excellent acid and solvent resistance. Metal sorption capacities of silica-based membrane sorbents possess metal sorption capacities approaching those of cellulosic-based membranes, with the added benefits of excellent acid and solvent resistance. Metal sorption capacities of silica-based membrane sorbents with various polyamino acids range from 0.6 mmol to 1.4 mmol of metal/g of sorbent. Ion exchange, chelation, and electrostatic interactions form the basis of metal sorption. Electrostatic interactions are greatly magnified in membrane-based sorbents, and are partly responsible for their high capacities. Regeneration of these sorbents has also been shown, including the possibility for selective desorption of metals.

  4. Preparation and evaluation of composite membrane for vanadium redox battery applications

    NASA Astrophysics Data System (ADS)

    Chieng, S. C.; Kazacos, M.; Skyllas-Kazacos, M.

    A composite membrane has been fabricated from Daramic (a microporous separator), treated with Amberlite 400CG (an ion-exchange resin), and cross-linked using divinyl benzene. Coulombic, voltage and energy efficiencies of 95, 85 and 83%, respectively, have been achieved when this membrane is employed in the vanadium redox cell. Long-term charge/discharge cycling has been conducted on the membrane for more than 700 cycles (4000 h), without any appreciable drop in performance. The composite membrane satisfies the stability, low area resistance, selectivity, and low-cost requirements for use as a separator in the vanadium redox battery.

  5. 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.

  6. Controlled release and antibacterial activity of tetracycline hydrochloride-loaded bacterial cellulose composite membranes.

    PubMed

    Shao, Wei; Liu, Hui; Wang, Shuxia; Wu, Jimin; Huang, Min; Min, Huihua; Liu, Xiufeng

    2016-07-10

    Bacterial cellulose (BC) is widely used in biomedical applications. In this study, we prepared an antibiotic drug tetracycline hydrochloride (TCH)-loaded bacterial cellulose (BC) composite membranes, and evaluated the drug release, antibacterial activity and biocompatibility. The structure and morphology of the fabricated BC-TCH composite membranes were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TCH release results show that the incorporation of BC matrix to load TCH is able to control the release. In vitro antibacterial assay demonstrate that the developed BC-TCH composites displayed excellent antibacterial activity solely associated with the loaded TCH drug. More importantly, the BC-TCH composite membranes display good biocompatibility. These characteristics of BC-TCH composite membranes indicate that they may successfully serve as wound dressings and other medical biomaterials.

  7. Burn-Resistant, Strong Metal-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel M.; Tayal, Moti J.

    2003-01-01

    Ceramic particulate fillers increase the specific strengths and burn resistances of metals: This is the conclusion drawn by researchers at Johnson Space Center's White Sands Test Facility. The researchers had theorized that the inclusion of ceramic particles in metal tools and other metal objects used in oxygen-rich atmospheres (e.g., in hyperbaric chambers and spacecraft) could reduce the risk of fire and the consequent injury or death of personnel. In such atmospheres, metal objects act as ignition sources, creating fire hazards. However, not all metals are equally hazardous: some are more burn-resistant than others are. It was the researchers purpose to identify a burn-resistant, high-specific-strength ceramic-particle/metal-matrix composite that could be used in oxygen-rich atmospheres. The researchers studied several metals. Nickel and cobalt alloys exhibit high burn resistances and are dense. The researchers next turned to ceramics, which they knew do not act as ignition sources. Unlike metals, ceramics are naturally burn-resistant. Unfortunately, they also exhibit low fracture toughnesses.

  8. Electroless synthesis of cellulose-metal aerogel composites

    NASA Astrophysics Data System (ADS)

    Schestakow, M.; Muench, F.; Reimuth, C.; Ratke, L.; Ensinger, W.

    2016-05-01

    An environmentally benign electroless plating procedure enables a dense coating of silver nanoparticles onto complex cellulose aerogel structures. In the course of the nanoparticle deposition, the morphological characteristics of the aerogel are preserved, such as the continuous self-supporting network structure. While achieving a high metal loading, the large specific surface area as well as the low density is retained in the cellulose-metal aerogel composite. Due to the interesting features of cellulose aerogel substrates (e.g., the accessibility of its open-porous network) and electroless plating (e.g., the possibility to control the density, size, and composition of the deposited metal nanoparticles), the outlined synthetic scheme provides a facile and flexible route towards advanced materials in heterogeneous catalysis, plasmonics, and sensing.

  9. Membrane Composition Tunes the Outer Hair Cell Motor

    NASA Astrophysics Data System (ADS)

    Rajagopalan, L.; Sfondouris, J.; Oghalai, J. S.; Pereira, F. A.; Brownell, W. E.

    2009-02-01

    Cholesterol and docosahexaenoic acid (DHA), an ω-3 fatty acid, affect membrane mechanical properties in different ways and modulate the function of membrane proteins. We have probed the functional consequence of altering cholesterol and DHA levels in the membranes of OHCs and prestin expressing HEK cells. Large, dynamic and reversible changes in prestin-associated charge movement and OHC motor activity result from altering the concentration of membrane cholesterol. Increasing membrane cholesterol shifts the q/V function ~ 50 mV in the hyperpolarizing direction, possibly a response related to increases in membrane stiffness. The voltage shift is linearly related to total membrane cholesterol. Increasing cholesterol also decreases the total charge moved in a linear fashion. Decreasing membrane cholesterol shifts the q/V function ~ 50 mV in the depolarizing direction with little or no effect on the amount of charge moved. In vivo increases in membrane cholesterol transiently increase but ultimately lead to decreases in DPOAE. Docosahexaenoic acid shifts the q/V function in the hyperpolarizing direction < 15 mV and increases total charge moved. Tuning of cochlear function by membrane cholesterol contributes to the exquisite temporal and frequency processing of mammalian hearing by optimizing the cochlear amplifier.

  10. Thermal expansion behavior of LDEF metal matrix composites

    NASA Technical Reports Server (NTRS)

    Le, Tuyen D.; Steckel, Gary L.

    1993-01-01

    The thermal expansion behavior of Long Duration Exposure Facility (LDEF) metal matrix composite materials was studied by (1) analyzing the flight data that was recorded on orbit to determine the effects of orbital time and heating/cooling rates on the performance of the composite materials, and (2) characterizing and comparing the thermal expansion behavior of post-flight LDEF and lab-control samples. The flight data revealed that structures in space are subjected to nonuniform temperature distributions, and thermal conductivity of a material is an important factor in establishing a uniform temperature distribution and avoiding thermal distortion. The flight and laboratory data showed that both Gr/Al and Gr/Mg composites were stabilized after prolonged thermal cycling on orbit. However, Gr/Al composites showed more stable thermal expansion behavior than Gr/Mg composites and offer advantages for space structures particularly where very tight thermal stability requirements in addition to high material performance must be met.

  11. A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Wang, Zhiwei; Zhang, Junyao; Zhang, Xingran; Ma, Jinxing; Wu, Zhichao

    2015-03-01

    Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

  12. A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors

    PubMed Central

    Huang, Jian; Wang, Zhiwei; Zhang, Junyao; Zhang, Xingran; Ma, Jinxing; Wu, Zhichao

    2015-01-01

    Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs. PMID:25784160

  13. A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors.

    PubMed

    Huang, Jian; Wang, Zhiwei; Zhang, Junyao; Zhang, Xingran; Ma, Jinxing; Wu, Zhichao

    2015-03-18

    Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs.

  14. Probabilistic fatigue life prediction of metallic and composite materials

    NASA Astrophysics Data System (ADS)

    Xiang, Yibing

    Fatigue is one of the most common failure modes for engineering structures, such as aircrafts, rotorcrafts and aviation transports. Both metallic materials and composite materials are widely used and affected by fatigue damage. Huge uncertainties arise from material properties, measurement noise, imperfect models, future anticipated loads and environmental conditions. These uncertainties are critical issues for accurate remaining useful life (RUL) prediction for engineering structures in service. Probabilistic fatigue prognosis considering various uncertainties is of great importance for structural safety. The objective of this study is to develop probabilistic fatigue life prediction models for metallic materials and composite materials. A fatigue model based on crack growth analysis and equivalent initial flaw size concept is proposed for metallic materials. Following this, the developed model is extended to include structural geometry effects (notch effect), environmental effects (corroded specimens) and manufacturing effects (shot peening effects). Due to the inhomogeneity and anisotropy, the fatigue model suitable for metallic materials cannot be directly applied to composite materials. A composite fatigue model life prediction is proposed based on a mixed-mode delamination growth model and a stiffness degradation law. After the development of deterministic fatigue models of metallic and composite materials, a general probabilistic life prediction methodology is developed. The proposed methodology combines an efficient Inverse First-Order Reliability Method (IFORM) for the uncertainty propogation in fatigue life prediction. An equivalent stresstransformation has been developed to enhance the computational efficiency under realistic random amplitude loading. A systematical reliability-based maintenance optimization framework is proposed for fatigue risk management and mitigation of engineering structures.

  15. Rapid induction bonding of composites, plastics, and metals

    NASA Technical Reports Server (NTRS)

    Buckley, John D.; Fox, Robert L.

    1991-01-01

    The Toroid Bonding Gun is and induction heating device. It is a self contained, portable, low powered induction welding system developed for bonding or joining plastic, ceramic, or metallic parts. Structures can be bonded in a factory or in a the field. This type of equipment allows for applying heat directly to the bond lines and/or to the adhesives without heating the entire structure, supports, and fixtures of a bonding assembly. The induction heating gun originally developed for use in the fabrication of space Gangs of bonders are now used to rapidly join composite sheet and structural components. Other NASA-developed applications of this bonding technique include the joining of thermoplastic composites, thermosetting composites, metals, and combinations of these materials.

  16. Characterization of ultrastructure and collagen composition of the teratoma membrane: comparison to the amniotic membrane.

    PubMed

    Kim, Kyung Sook; Cho, Chang-Hoon; Kim, Young-Sun; Yoon, Kyung-Sik; Jung, Min-Hyung; Park, Hun-Kuk

    2013-04-01

    The structural and morphological properties of the teratoma membrane were investigated to better understand the pathogenesis of ovarian teratomas. A mature cystic teratoma and amnion were obtained from patients who underwent laparoscopic cystectomy and uncomplicated delivery, respectively. The teratoma membrane was divided into three layers according to the results of the histological analysis. Each layer showed distinct morphological properties, including an outer layer that was uniformly arranged, a middle layer with an irregular pattern of fibers, and an inner layer that was structurally dense with a wavy pattern of fibers. The morphology of the layers of the amniotic membrane was the reverse that of the teratoma membrane. In the teratoma membrane, the outer layer was primarily composed of type III collagen and the inner layer had a large amount of type III and IV collagen. The amniotic membrane showed a small amount of type III collagen in the outer layer, whereas the inner layer had large amounts of type I, III, and IV collagen. In the teratoma membrane, the collagen fibrils were arranged regularly in the outer layer, but irregularly in the inner layer. In the amniotic membrane, the arrangement of collagen fibrils was the reverse that of the teratoma membrane. Additionally, the collagen fibrils in the teratoma membrane were thinner than those of the amniotic membrane and had slightly shorter d-spacing. Two membranes showed the differences in collagen fibril arrangement, which may caused by the different functional roles.

  17. Modeling and Analysis on Pervaporation Separation of Composite Zeolite Membranes

    NASA Astrophysics Data System (ADS)

    Mann, Stewart

    Pervaporation is a membrane separation technology that has had industrial application and which is the subject of ongoing research. Two major factors are important in judging the quality of a membrane: selectivity and permeation flux. Although many types of materials can be used for the separation layer, zeolites will be the material considered in this thesis. A simple mathematical model has been developed to demonstrate the inter-relationships between relative permeation flux, reduced selectivity, and the relative resistance to mass transfer of the support to the zeolite layer. The model was applied to several membranes from our laboratory and to two examples from the literature. The model offers a useful way of conceptualizing membrane performance and facilitates the comparison of different membrane performances. The model predicts the effect of different supports on zeolite supported membrane performance.

  18. Exceptionally strong and robust millimeter-scale graphene-alumina composite membranes.

    PubMed

    Berdova, Maria; Perros, Alexander Pyymaki; Kim, Wonjae; Riikonen, Juha; Ylitalo, Tuomo; Heino, Jouni; Li, Changfeng; Kassamakov, Ivan; Hæggström, Edward; Lipsanen, Harri; Franssila, Sami

    2014-09-05

    Graphene has attracted attention as a potential strengthening material and functional component in suspended membranes as utilized in micro and nanosystems. Development of a practical and scalable fabrication process is a necessary step to allow the exceptional material properties of graphene to be fully exploited in composite structures. Using standard and scalable microfabrication processes, we fabricated free-standing chemical vapor deposition monolayer graphene-reinforced Al2O3 composite membranes, 0.5 mm in diameter, that are strong and robust. Bulge tests revealed that the graphene reinforcement increased the membrane fracture strength by a factor of at least three and maximum sustainable strain from 0.28% to at least 0.69%. We show that the graphene-reinforced membranes are even tolerant to significant cracking without loss of membrane integrity. The graphene composite membranes' freestanding area of ∼ 200 000 μm(2) is almost a thousand times larger than suspended graphene membranes reported elsewhere. The presented graphene composite membranes may be seen as representing an interesting new class of durable composite materials warranting further study and having potential for broad applicability in a variety of fields.

  19. Hydrophilic nanofibers as new supports for thin film composite membranes for engineered osmosis.

    PubMed

    Bui, Nhu-Ngoc; McCutcheon, Jeffrey R

    2013-02-05

    Engineered osmosis (e.g., forward osmosis, pressure-retarded osmosis, direct osmosis) has emerged as a new platform for applications to water production, sustainable energy, and resource recovery. The lack of an adequately designed membrane has been the major challenge that hinders engineered osmosis (EO) development. In this study, nanotechnology has been integrated with membrane science to build a next generation membrane for engineered osmosis. Specifically, hydrophilic nanofiber, fabricated from different blends of polyacrylonitrile and cellulose acetate via electrospinning, was found to be an effective support for EO thin film composite membranes due to its intrinsically wetted open pore structure with superior interconnectivity. The resulting composite membrane exhibits excellent permselectivity while also showing a reduced resistance to mass transfer that commonly impacts EO processes due to its thin, highly porous nanofiber support layer. Our best membrane exhibited a two to three times enhanced water flux and 90% reduction in salt passage when compared to a standard commercial FO membrane. Furthermore, our membrane exhibited one of the lowest structural parameters reported in the open literature. These results indicate that hydrophilic nanofiber supported thin film composite membranes have the potential to be a next generation membrane for engineered osmosis.

  20. Engineering plasmonic metal colloids through composition and structural design.

    PubMed

    Motl, N E; Smith, A F; DeSantis, C J; Skrabalak, S E

    2014-06-07

    The optical properties of metal nanomaterials are determined by a set of parameters that include composition, particle size and shape, overall architecture, and local environment. This Tutorial Review examines the influence of each of these factors on the localized surface plasmon resonance of colloidal metal nanoparticles. This examination is paralleled with a discussion of the advances which have enabled the synthesis of structurally defined metal nanomaterials, as these samples serve as the best platforms for elucidating the fundamental properties of plasmonic colloids. Based on the analysis of such samples, five guidelines are presented to aid the rational design and synthesis of new metal nanostructures for advanced applications in nanomedicine, energy, chemical sensing, and colloidal plasmonics in general.

  1. Preparation of new composite membranes for water desalination using electrodialysis

    NASA Astrophysics Data System (ADS)

    Klaysom, Chalida; Germain, Leatitia; Burr, Shawn; Ladewig, Bradley P.; Wang, Lianzhou; da Costa, Joe D.; Lu, G. Q. M.

    2008-12-01

    The use of polyethersulfone (PES), an excellent but highly hydrophobic thermoplastic, as a matrix material for ionexchange membranes was investigated. To make PES ion-exchangeable, sulfonate groups were introduced to the polymer chains by sulfonation reaction with chlorosulfonic acid. The degree of sulfonation of sPES was estimated to be 21%. Preliminary experiments investigated the effect of polyethylene glycol (PEG) and Pluronic F127 as fillers to improve the hydrophilicity of the membranes. Moreover, a lab scale electrodialysis cell has been designed and set up to evaluate the performance of these novel membranes compared to the benchmark of commercial membranes. The results show promising properties of ion-exchange capacity, water uptake, conductivity and hydophilicity from blended membranes, comparable to commercial membranes, though the performance of the prepared membranes did not exceed the commercial one. Further characterization of the transport properties of ion-exchange membranes need to be investigated to be able to understand the effects of the fillers on the performance of the membranes in ED application.

  2. Metal-ceramic laminate composite magnetoelectric gradiometer.

    PubMed

    Bedekar, V; Bichurin, M I; Ivanov, S N; Pukinski, Y J; Priya, S

    2010-03-01

    Gradiometer resembles in functionality a magnetic field sensor where it measures the magnetic field gradient and its sensitivity is determined by the ability to quantify differential voltage change with respect to a reference value. Magnetoelectric (ME) gradiometer designed in this study is based upon the nickel (Ni)-Pb(Zr,Ti)O(3) (PZT) composites and utilizes the ring-dot piezoelectric transformer structure working near the resonance as the basis. The samples had the ring-dot electrode pattern printed on the top surface of PZT, where ring acts as the input while dot acts as the output. There is an insulation gap between the input and output section of 1.2 mm. The generated magnetic field due to converse ME effect interacts with the external applied magnetic field producing flux gradient, which is detected through the frequency shift and output voltage change in gradiometer structure. The measurements of output voltage dependence on applied magnetic field clearly illustrate that the proposed design can provide high sensitivity and bandwidth.

  3. Membrane crystallinity and fuel crossover in direct ethanol fuel cells with Nafion composite membranes containing phosphotungstic acid

    SciTech Connect

    Kim, Hongjun; Lee, Sunghwan; Kim, Suran; Oh, Chungik; Ryu, Jeongjae; Kim, Jaegyu; Park, Eugene; Hong, Seungbum; No, Kwangsoo

    2016-11-01

    Interest has been growing in direct ethanol fuel cells (DEFCs) due to their non-toxicity, low cost and potential contribution to energy issues in third world countries. A reduction in fuel cross-over is of key importance to enhance the performance of DEFCs that operate at low temperatures (<100 °C). We report on the effect of the addition of phosphotungstic acid (PWA) in Nafion membrane on the ethanol-crossover for DEFC application. A set of PWANafion composite membranes (PWA 0, 5, 10, 15, 20 wt%) was prepared by solution casting and their microstructures, diffraction patterns and permeability were systematically characterized. The significant reduction in ethanol-crossover was observed with increasing PWA concentration in PWA-Nafion membranes, which was mainly attributed to an improvement in crystallinity of the membrane. PWA provides additional nucleation sites during solidification leading to higher crystallinity, which is supported by the membrane permeability tests. These PWA-Nafion composites were implemented in proto-type DEFC devices as a membrane and the maximum power density achieved was 22% higher than that of commercial Nafion-117 device.

  4. Soft metal constructs for large strain sensor membrane

    NASA Astrophysics Data System (ADS)

    Michaud, Hadrien O.; Teixidor, Joan; Lacour, Stéphanie P.

    2015-03-01

    Thin gold films on silicone display large reversible change in electrical resistance upon stretching. Eutectic liquid metal conductors maintain bulk metal conductivity, even upon extensive elongation. When integrated together, the soft metals enable multidirectional, large strain sensor skin. Their fabrication process combines thermal evaporation of thin gold film patterns through stencil mask with microplotting of eutectic gallium indium microwires, and packaging in silicone rubber. Using three-element rectangular rosettes, we demonstrate a sensor skin that can reliably and locally quantify the plane strain vector in surfaces subject to stretch (up to 50% strain) and indentation. This hybrid technology will find applications in soft robotics, prosthetics and wearable health monitoring systems.

  5. High-performance zeolite NaA membranes on polymer-zeolite composite hollow fiber supports.

    PubMed

    Ge, Qinqin; Wang, Zhengbao; Yan, Yushan

    2009-12-02

    We report a new strategy: use of polymer-zeolite composite hollow fibers as supports. Zeolite membranes with high performance (flux = 8.0-9.0 kg m(-2) h(-1), alpha >10 000) can be synthesized directly on polymer-zeolite composite hollow fiber supports by a single in situ hydrothermal crystallization. The zeolite crystals imbedded in the polymer hollow fiber serve as seeds for the zeolite membrane growth, and they also "anchor" the zeolite membrane to the support to increase the adhesion of the zeolite membrane. Therefore, a separate and often complex seeding process can be omitted. A very uniform crystal distribution can be obtained easily, so continuous zeolite membranes can be prepared with high reproducibility. These composite hollow fibers can be produced simply by blending zeolite crystals into the polymer feed before the hollow fiber extrusion and thus are expected to be inexpensive.

  6. 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.

  7. Reverse osmosis performance of modified polyvinyl alcohol thin-film composite membranes

    SciTech Connect

    Lang, K.; Chowdhury, G.; Matsuura, T.; Sourirajan, S. )

    1994-08-01

    Membrane separation characteristics in the nanofiltration (NF) and reverse osmosis (RO) regions of the filtration spectrum are governed by a complex combination of both steric hindrance and surface force interactions. NF and RO membranes having surface charges show unusual selectivity behavior not predicted on the basis of physical pore size alone. Hence, practical characterizations should employ techniques to gain insight on membrane function. In this work, the separation characteristics of an anionically charged modified polyvinyl alcohol (PVA) thin-film composite membrane under different operating pressures were investigated. A qualitative measurement of the surface force interactions between solutes and membrane polymer was conducted using liquid chromatography technique. An attempt was also made to study the chlorine resistance of the composite membrane.

  8. Synthesis of silicalite-poly(furfuryl alcohol) composite membranes for oxygen enrichment from air

    PubMed Central

    2011-01-01

    Silicalite-poly(furfuryl alcohol) [PFA] composite membranes were prepared by solution casting of silicalite-furfuryl alcohol [FA] suspension on a porous polysulfone substrate and subsequent in situ polymerization of FA. X-ray diffraction, nitrogen sorption, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to characterize silicalite nanocrystals and silicalite-PFA composite membranes. The silicalite-PFA composite membrane with 20 wt.% silicalite loading exhibits good oxygen/nitrogen selectivity (4.15) and high oxygen permeability (1,132.6 Barrers) at 50°C. Silicalite-PFA composite membranes are promising for the production of oxygen-enriched air for various applications. PMID:22209012

  9. Synthesis of silicalite-poly(furfuryl alcohol) composite membranes for oxygen enrichment from air

    NASA Astrophysics Data System (ADS)

    He, Li; Li, Dan; Wang, Kun; Suresh, Akkihebbal K.; Bellare, Jayesh; Sridhar, Tam; Wang, Huanting

    2011-12-01

    Silicalite-poly(furfuryl alcohol) [PFA] composite membranes were prepared by solution casting of silicalite-furfuryl alcohol [FA] suspension on a porous polysulfone substrate and subsequent in situ polymerization of FA. X-ray diffraction, nitrogen sorption, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to characterize silicalite nanocrystals and silicalite-PFA composite membranes. The silicalite-PFA composite membrane with 20 wt.% silicalite loading exhibits good oxygen/nitrogen selectivity (4.15) and high oxygen permeability (1,132.6 Barrers) at 50°C. Silicalite-PFA composite membranes are promising for the production of oxygen-enriched air for various applications.

  10. Synthesis of silicalite-poly(furfuryl alcohol) composite membranes for oxygen enrichment from air.

    PubMed

    He, Li; Li, Dan; Wang, Kun; Suresh, Akkihebbal K; Bellare, Jayesh; Sridhar, Tam; Wang, Huanting

    2011-12-30

    Silicalite-poly(furfuryl alcohol) [PFA] composite membranes were prepared by solution casting of silicalite-furfuryl alcohol [FA] suspension on a porous polysulfone substrate and subsequent in situ polymerization of FA. X-ray diffraction, nitrogen sorption, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to characterize silicalite nanocrystals and silicalite-PFA composite membranes. The silicalite-PFA composite membrane with 20 wt.% silicalite loading exhibits good oxygen/nitrogen selectivity (4.15) and high oxygen permeability (1,132.6 Barrers) at 50°C. Silicalite-PFA composite membranes are promising for the production of oxygen-enriched air for various applications.

  11. The effect of organic loading on bacterial community composition of membrane biofilms in a submerged polyvinyl chloride membrane bioreactor.

    PubMed

    Xia, Siqing; Li, Jixiang; He, Shuying; Xie, Kang; Wang, Xiaojia; Zhang, Yanhao; Duan, Liang; Zhang, Zhiqiang

    2010-09-01

    The effect of organic loading on bacterial community composition of membrane biofilms was investigated using a submerged polyvinyl chloride membrane bioreactor. The low and high loadings were set at 0.33 and 0.52 gCOD/(gVSSd), respectively. The results showed that membrane fouling occurred earlier and faster under the high loading conditions. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that the similarity of bacterial community in the membrane biofilms between the two loadings was 0.67, higher than that in the mixed liquors (0.52-0.55), which indicated that some specific bacteria were selected preferentially on the membranes. Clone library analysis of the membrane biofilms indicated that Betaproteobacteria and Bacteroidetes under the high loading were 54.72% and 19.81%, respectively. Microarray results further confirmed that the two bacteria were the dominant microorganisms in the high loading biofilm. The severe membrane fouling may be aroused mainly by the enrichment of the two bacteria under the high loading.

  12. Making a Metal-Lined Composite-Overwrapped Pressure Vessel

    NASA Technical Reports Server (NTRS)

    DeLay, Tom

    2005-01-01

    process has been devised for the fabrication of a pressure vessel that comprises a composite-material (matrix/fiber) shell with a metal liner on its inner surface. The use of the composite material makes it possible for the tank to be strong enough to withstand the anticipated operating pressure and yet weigh less than does an equivalent all-metal tank. The metal liner is used as a barrier against permeation: In the absence of such a barrier, the pressurized gas in the tank could leak by diffusing through the composite-material shell. The figure depicts workpieces at four key stages in the process, which consists of the following steps: 1. A mandrel that defines the size and shape of the pressure vessel is made by either molding or machining a piece of tooling wax. 2. Silver paint is applied to the surface of the mandrel to make it electrically conductive. 3. The ends of the mandrel are fitted with metal bosses. 4. The mandrel is put into a plating bath, wherein the metal liner is electrodeposited. Depending on the applications, the liner metal could be copper, nickel, gold, or an alloy. Typical liner thicknesses range from 1 to 10 mils (0.025 to 0.25 mm). 5. The wax is melted from within, leaving the thin metal liner. 6. A hollow shaft that includes holes and fittings through which the liner can be pressurized is sealed to both ends of the liner. The liner is pressurized to stiffen (and hence stabilize) it for the next step. 7. The pressurized liner is placed in a filament-winding machine, which is then operated to cover the liner with multiple layers of an uncured graphite-fiber/epoxy-matrix or other suitable composite material. 8. The composite-overwrapped liner is cured in an oven. 9. The pressure is relieved and the shaft is removed. The tank is then ready for use. The process as described above accommodates variations: a) The mandrel could be made of a wax that melts at a higher temperature and not removed until the tank is cured in the oven. b) The tank need

  13. SOLAR METALLICITY DERIVED FROM IN SITU SOLAR WIND COMPOSITION

    SciTech Connect

    Von Steiger, R.; Zurbuchen, T. H. E-mail: thomasz@umich.edu

    2016-01-01

    We use recently released solar wind compositional data to determine the metallicity of the Sun—the fraction per unit mass that is composed of elements heavier than He. We focus on a present-day solar sample available to us, which is the least fractionated solar wind from coronal holes near the poles of the Sun. Using these data, we derive a metallicity of Z = 0.0196 ± 0.0014, which is significantly larger than recent published values based on photospheric spectroscopy, but consistent with results from helioseismology.

  14. The Role of the Interface in Refractory Metal Alloy Composites

    NASA Technical Reports Server (NTRS)

    Grobstein, Toni; Yun, Hee M.

    1991-01-01

    Creep-rupture and tensile tests have been used to evaluate thoriated W-wire reinforced Nb-1 percent Zr alloy matrix composites fabricated via arc-spray monotape technique. A significant creep strength enhancement was observed over the unreinforced matrix alloy while matrix integrity was maintained; the fiber/matrix interface phase is noted to be a strong and ductile W/Nb alloy, which is formed due to the mutual solubility of the constituent metals. High strength, toughness, and thermal stability are demonstrated by this material system, which is also resistant to liquid alkali metal corrosion.

  15. Innovative Technologies to Manufacture Hybrid Metal Foam/Composite Components

    SciTech Connect

    Carrino, L.; Durante, M.; Franchitti, S.; Sorrentino, L.; Tersigni, L.

    2011-01-17

    The aim of this paper is to verify the technological feasibility to realize hybrid metal-foam/composite component and the mechanical performances of the final structure. The hybrid component is composed by a cylindrical core in aluminum foam, the most used between those commercially available, and an outer layer in epoxy/S2-glass, manufactured by filament winding technology.A set of experimental tests have been carried out, to the aim to estimate the improvement of the hybrid component characteristics, compared to the sum of the single components (metal foam cylinder and epoxy/S2-glass tube).

  16. Influence of Filler Metals in Welding Wires on the Phase and Chemical Composition of Weld Metal

    NASA Astrophysics Data System (ADS)

    Kozyrev, N. A.; Osetkovskiy, I. V.; Kozyreva, O. A.; Zernin, E. A.; Kartsev, D. S.

    2016-04-01

    The influence of filler metals used in welding wires on the phase and chemical composition of the metal, which is surfaced to mining equipment exposed to abrasive wear, has been investigated. Under a laboratory environment, samples of Mo-V-B and Cr-Mn-Mo-V wires were made. The performed experiments have revealed that fillers of the Cr-Mn-Mo-V system used in powder wire show better wear resistance of the weld metal than that of the Mn-Mo-V-B system; the absence of boron, which promotes grain refinement in the Mn-Mo-V-B system, significantly reduces wear resistance; the Mn-Mo-V-B weld metal has a finer structure than the Cr-Mn-Mo-V weld metal.

  17. Electrochemically reduced graphene oxide / sulfonated polyether ether ketone composite membrane for electrochemical applications

    NASA Astrophysics Data System (ADS)

    Seetharaman, S.; Ramya, K.; Dhathathreyan, K. S.

    2013-06-01

    A simple and effective method for the preparation of sulfonated polyether ether ketone (SPEEK) based composites with electrochemical reduced graphene oxide (EGO) as inorganic fillers has been described. The resulting dispersions are homogeneous and the cast membranes show significant improvement on tensile strength and thermal properties. It has high ionic conductivity and is cost effective making it a promising alternative membrane for electrochemical applications.

  18. Adhesion and hemifusion of cytoplasmic myelin lipid membranes are highly dependent on the lipid composition

    PubMed Central

    Banquy, Xavier; Kristiansen, Kai; Lee, Dong Woog; Israelachvili, Jacob N.

    2012-01-01

    We report the effects of calcium ions on the adhesion and hemifusion mechanisms of model supported myelin lipid bilayer membranes of differing lipid composition. As in our previous studies [1, 2], the lipid compositions used mimic “healthy” and “diseased-like” (experimental autoimmune encephalomyelitis, EAE) membranes. Our results show that the interaction forces as a function of membrane separation distance are well described by a generic model that also (and in particular) includes the hydrophobic interaction arising from the hydrophobically exposed (interior) parts of the bilayers. The model is able to capture the mechanical instability that triggers the onset of the hemifusion event, and highlights the primary role of the hydrophobic interaction in membrane fusion. The effects of lipid composition on the fusion mechanism, and the adhesion forces between myelin lipid bilayers, can be summarized as follow: in calcium-free buffer, healthy membranes do not present any signs of adhesion or hemifusion, while diseased membranes hemifuse easily. Addition of 2 mM calcium favors adhesion and hemifusion of the membranes independently of their composition, but the mechanisms involved in the two processes were different: healthy bilayers systematically presented stronger adhesion forces and lower energy barriers to fusion compared to diseased bilayers. These results are of particular relevance for understanding lesion development (demyelination, swelling, vacuolization and/or vesiculation) in myelin associated diseases such as multiple sclerosis and its relationship to lipid domain formation in myelin membranes. PMID:22047743

  19. 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.

  20. Nonhazardous solvent composition and method for cleaning metal surfaces

    DOEpatents

    Googin, John M.; Simandl, Ronald F.; Thompson, Lisa M.

    1993-01-01

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140.degree. F. and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140.degree. F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

  1. Nonhazardous solvent composition and method for cleaning metal surfaces

    DOEpatents

    Googin, J.M.; Simandl, R.F.; Thompson, L.M.

    1993-05-04

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140 F and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140 F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

  2. Wear and friction behavior of metal impregnated microporous carbon composites

    SciTech Connect

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

    1996-11-01

    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.

  3. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, Toni L.

    1992-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  4. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, T. L.

    1989-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared on a strength to density basis. The effect of fiber orientation on the creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  5. Screening of metal matrix composites using ultrasonic C-scans

    SciTech Connect

    Johnson, W.S.

    1989-01-01

    Ultrasonic C-scans can be used to find some types of defects in continuous fiber-reinforced metal matrix composites such as boron/aluminum composites. These defects are related to the fatigue behavior and fracture location of each inspected specimen. The C-scan technique determined the relative amount of defects in boron/aluminum composites. The defects were primarily identified as gaps in the fiber spacing. Those specimens with higher defect densities had shorter fatigue lives, lower fatigue endurance limits, and greater reductions in the elastic unloading modulus (that is, stiffness) because of fatigue cycling. This type of data could be used to set accept/reject levels for a composite panel based on C-scan indications. 8 refs.

  6. NOVEL COMPOSITE MEMBRANES AND PROCESS FOR NATURAL GAS UPGRADING

    SciTech Connect

    Ben Bikson; Sal Giglia; Jibin Hao

    2003-03-01

    In the second phase of this project, the newly developed membrane module for natural gas dehydration was tested and evaluated in a pilot plant located at a commercial natural gas treatment site. This phase was undertaken jointly with UOP LLC, our commercialization partner. The field test demonstrated that a commercial-size membrane module for natural gas dehydration was successfully manufactured. The membrane module operated reliably over 1000 psi differential pressure across the membrane in the field test. The effects of feed gas pressure, permeate gas pressure, feed flow rate, purge ratio (flow rate ratio of permeate outlet to feed), and feed gas dew point on the membrane module performance were determined and found to meet the design expectations. Although water vapor permeance was lower than expected, substantial natural gas dehydration was demonstrated with low purge ratio. For example, dew point was suppressed by as much as 30 F with only about 2 {approx} 3% purge ratio. However the bore side pressure drops were significantly higher than the projected value from the fluid dynamic calculation. It is likely that not all the fibers were open in either the sweep or the permeate tube sheet end. This could help to explain the relatively low water vapor permeances that were measured in the field. An economic evaluation of the membrane process and the traditional Triethylene Glycol (TEG) process to dehydrate natural gas was performed and the economics of the two processes were compared. Two sets of membrane module performance properties were used in the economic analysis of the membrane process. One was from the results of this field test and the other from the results of the previous small-scale test with a medium pressure membrane variant conducted at 750 psig. The membrane process was competitive with the TEG process for the natural gas feed flow rate below 10 MMSCFD for the membrane with previously measured water vapor permeance. The membrane process was

  7. Preparation and Characterization of a Hydrophobic Metal-Organic Framework Membrane Supported on Thin Porous Metal Sheet

    SciTech Connect

    Liu, Jian; Canfield, Nathan L.; Liu, Wei

    2016-02-29

    A hydrophobic metal-organic framework (MOF) UiO-66-CH3 is prepared and its solvothermal stability is investigated in comparison to UiO-66. It is confirmed that the MOF stability is enhanced by introduction of the two methyl groups, while the water adsorption is reduced. Given its hydrophobicity and stability, UiO-66-CH3 is proposed as an attractive membrane material for gas separation under moisture conditions. The UiO-66-CH3 membrane is prepared on a 50µm-thin porous Ni support sheet for the first time by use of a secondary growth method. It is found that uniform seed coating on the support is necessary to form a continuous membrane. In addition to growth time and temperature, presence of a modulator in the growth solution is found to be useful for controlling hydrothermal membrane growth on the seeded support. A dense, inter-grown membrane layer is formed by 24-h growth over a temperature range from 120 oC to 160 oC. The membrane surface comprises 500 nm octahedral crystals, which are supposed to grow out of the original 100 nm spherical seeding crystals. The separation characteristics of resulting membranes are tested with pure CO2, air, CO2/air mixture, and humid CO2/air mixture. CO2 permeance as high as 1.9E-06 mol/m2/s/Pa at 31oC is obtained. Unlike the hydrophilic zeolite membranes, CO2 permeation through this membrane is not blocked by the presence of water vapor in the feed gas. The results suggest that this MOF framework is a promising membrane material worth to be further investigated for separation of CO2 and other small molecules from humid gas mixtures.

  8. Metal matrix composite micromechanics: In-situ behavior influence on composite properties

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Hopkins, D. A.; Chamis, C. C.

    1989-01-01

    Recent efforts in computational mechanics methods for simulating the nonlinear behavior of metal matrix composites have culminated in the implementation of the Metal Matrix Composite Analyzer (METCAN) computer code. In METCAN material nonlinearity is treated at the constituent (fiber, matrix, and interphase) level where the current material model describes a time-temperature-stress dependency of the constituent properties in a material behavior space. The composite properties are synthesized from the constituent instantaneous properties by virtue of composite micromechanics and macromechanics models. The behavior of metal matrix composites depends on fabrication process variables, in situ fiber and matrix properties, bonding between the fiber and matrix, and/or the properties of an interphase between the fiber and matrix. Specifically, the influence of in situ matrix strength and the interphase degradation on the unidirectional composite stress-strain behavior is examined. These types of studies provide insight into micromechanical behavior that may be helpful in resolving discrepancies between experimentally observed composite behavior and predicted response.

  9. SURFACE MODIFICATION OF SILICA- AND CELLULOSE-BASED MICROFILTRATION MEMBRANES WITH FUNCTIONAL POLYAMINO ACIDS FOR HEAVY METAL SORPTION

    EPA Science Inventory

    Functionalized membranes represent a field with multiple applications. Examination of specific metal-macromolecule interactions on these surfaces presents an excellent method for characterizion of these materials. These interactions may also be exploited for heavy metal sorptio...

  10. Characterization of phospholipid composition and its control in the plasma membrane of developing soybean root

    SciTech Connect

    Whitman, C.E.

    1985-01-01

    The phospholipid composition of plasma membrane enriched fractions from developing soybean root and several mechanisms which may regulate it have been examined. Plasma membrane vesicles were isolated from meristematic and mature sections of four-day-old dark grown soybean roots (Glycine max (L.) Merr. Cult. Wells II). Analysis of lipid extracts revealed two major phospholipid classes: phosphatidylcholine and phosphatidylethanolamine. Minor phospholipid classes were phosphatidylinositol, phosphatidylserine, phosphatidylgylcerol and diphosphatidylgylcerol. Phospholipid composition was similar at each developmental stage. Fatty acids of phosphatidylcholine and phosphatidylethanolamine were 16:0, 18:0, 18:2, and 18:3. Fatty acid composition varied with both phospholipid class and the developmental stage of the root. The degradation of phosphatidylcholine by endogenous phospholipase D during membrane isolation indicated that this enzyme might be involved in phospholipid turnover within the membrane. Phospholipase D activity was heat labile and increasing the pH of the enzyme assay from 5.3 to 7.8 resulted in 90% inhibition of activity. The turnover of fatty acids within the phospholipids of the plasma membrane was studied. Mature root sections were incubated with (1-/sup 14/C) acetate, 1 mM Na acetate and 50 ..mu..g/ml chloramphenicol. Membrane lipid extracts analyzed for phospholipid class and acyl chain composition revealed that the long incubation times did not alter the phospholipid composition of the plasma membrane enriched fraction.

  11. Immobilization of imidazole moieties in polymer electrolyte composite membrane for elevated temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Ke; Zhou, Bei; Ye, Gongbo; Pan, Mu; Zhang, Haining

    2015-12-01

    Development of membrane electrolyte with reasonable proton conductivity at elevated temperature without external humidification is essential for practical applications of elevated temperature proton exchange membrane fuel cells. Herein, a novel polymer electrolyte composite membrane using imidazole as anhydrous proton carriers for elevated temperature fuel cells is investigated. The imidazole moieties are immobilized inside the Nafion/poly(tetrafluoroethylene) (PTFE) composite membrane through in situ formation of imidazole functionalized silica nanoparticles in Nafion dispersion. The thus-formed membrane exhibits strong Coulombic interaction between negatively charged sulfonic acid groups of Nafion and protonated imidazole moieties, leading to an anhydrous proton conductivity of 0.018 S cm-1 at 180 °C. With the introduction of PTFE matrix, the mechanical strength of the membrane is greatly improved. The peak power density of a single cell assembled from the hybrid membrane is observed to be 130 mW cm-2 under 350 mA cm-2 at 110 °C without external humidification and it remains stable for 20 h continuous operation. The obtained results demonstrate that the developed composite membranes could be utilized as promising membrane electrolytes for elevated temperature fuel cells.

  12. Space applications for ionic polymer-metal composite sensors, actuators, and artificial muscles

    NASA Astrophysics Data System (ADS)

    Krishen, Kumar

    2009-06-01

    Ionic polymer-metal composites (IPMCs) are composites of a noble metal, conductive polymer or carbon/graphite, and charged polyelectrolyte membrane. IPMCs have shown considerable progress in producing actuation in electric fields. These composites are also capable of sensing motion by producing a voltage difference when bent by a mechanical force. Work to date has yielded a force greater than 40 times the weight of an IPMC and large bending displacements with very low-input voltages. There is sufficient reason to believe that artificial muscles with viable strength can be produced with these composites. The IPMC, in addition to being resilient and elastic, is also lightweight and has a reaction speed that ranges from 1 microsecond to 1 second. For space missions, devices based on IPMCs will have numerous applications. On planetary surfaces, robotic arms and end effectors, motion-producing motors, actuators, and controllers are just a few examples of devices that can be produced using IPMCs. In this paper, examples of various envisioned space applications of IPMCs will be provided. The impacts of these applications on future space missions will also be discussed.

  13. Microstructure and strength of a deformation processed aluminum-20%tin metal-metal composite

    NASA Astrophysics Data System (ADS)

    Xu, Kai

    An Al-20vol.% Sn metal-metal composite was deformation processed by extrusion, swaging, and wire drawing to a total true strain of 7.4, resulting in a microstructure with Sn filaments in an Al matrix. Both the size and spacing of the Sn filaments decreased as deformation processing progressed. Immediately after deformation, the Sn second phase showed a convoluted, ribbon-shaped filamentary morphology, but the Sn filaments spheroidized during prolonged storage at room temperature. The driving force for spheroidization is chemical potential gradient due to curvature difference along Sn filaments. A critical wavelength of lambda crit = 2piR can be used to determine the spheroidization tendency of Sn cylinder. When lambda > 2piR, spheroidization is predicted to occur. The strength of these composites increased exponentially with the reduction in spacing of the Sn filaments. The relationship between UTS and deformation true strain is UTS = 72.6 exp(0.20eta). A Hall-Petch relationship between strength and filament spacing has been observed. Strengthening results from the filaments acting as barriers for dislocation motion. The primary shape instability modes are cylinderization of ribbons, boundary splitting, spheroidization of cylinders, and edge spheroidization of ribbons. The determining factors dictating which mechanism is active are grain boundary energy, interfacial energy, and ribbon cross section aspect ratio. The fiber texture was determined by orientation imaging microscopy to be <100> for Al and <001> for Sn. The 290 MPa ultimate tensile strength of the composite was greater than the rule-of-mixtures prediction. Comparisons are made with Al-Nb, Al-Ti and Al-Mg deformation processed metal metal composites and to various strengthening models for metal-metal composites.

  14. PALLADIUM/COPPER ALLOY COMPOSITE MEMBRANES FOR HIGH TEMPERATURE HYDROGEN SEPARATION

    SciTech Connect

    J. Douglas Way

    2004-08-31

    This report summarizes progress made during the first year of research funding from DOE Grant No. DE-FG26-03NT41792 at the Colorado School of Mines. The period of performance was September 1, 2003 through August of 2004. Composite membranes, consisting of a thin Pd alloy film supported on a porous substrate have been investigated as a means of reducing the membrane cost and improving H{sub 2} flux. An electroless plating technique was utilized to deposit subsequent layers of palladium and copper over zirconia and alumina-based microfilters. The composite membranes thus made were annealed and tested at temperatures ranging from 250 to 500 C, under very high feed pressures (up to 450 psig) using pure gases and gaseous mixtures containing H{sub 2}, CO, CO{sub 2}, H{sub 2}O and H{sub 2}S, with the purpose of determining the effects these variables had on the H{sub 2} permeation rate, selectivity and percent recovery. The inhibition caused by CO/CO{sub 2} gases on a 7 {micro}m thick Pd-Cu composite membrane was less than 17% over a wide range of compositions at 350 C. H{sub 2}S caused a strong inhibition of the H{sub 2} flux of the same Pd-Cu composite membrane, which is accentuated at levels of 100 ppm or higher. The membrane was exposed to 50 ppm three times without permanent damage. At higher H{sub 2}S levels, above 100 ppm the membrane suffered some physical degradation and its performances was severely affected. The use of sweep gases improved the hydrogen flux and recovery of a Pd-Cu composite membrane. Recently, we have been able to dramatically reduce the thickness of these Pd alloy membranes to approximately one micron. This is significant because at this thickness, it is the cost of the porous support that controls the materials cost of a composite Pd alloy membrane, not the palladium inventory. Very recent results show that the productivity of our membranes is very high, essentially meeting the DOE pure hydrogen flux target value set by the DOE Hydrogen

  15. TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

    PubMed

    Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

    2014-09-01

    A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

  16. Laminated metals composites fracture and ballistic impact behavior

    SciTech Connect

    Lesuer, D.R.; Syn, C.K.; Sherby, O.D.; Wadsworth, J.

    1998-01-20

    Recent advances in the fracture and ballistic impact response of laminated metal composites (LMCs) are reviewed. The laminate structure can provide significant improvements to these properties relative to the component materials. Typical fracture and ballistic impact properties in LMCs are illustrated for systems containing Al alloys and Al matrix composites. The unique mechanisms operating in a layered structure that contribute to fracture or ballistic impact resistance are discussed. The influence of laminate architecture, component material properties and interface strength on mechanisms and properties are briefly reviewed for these Al-based LMCs.

  17. Electrical conductivity of a bulk metallic glass composite

    NASA Astrophysics Data System (ADS)

    Wang, K.; Fujita, T.; Chen, M. W.; Nieh, T. G.; Okada, H.; Koyama, K.; Zhang, W.; Inoue, A.

    2007-10-01

    The authors report the electrical conductivity of a bulk metallic glass (BMG) based composite fabricated by warm extrusion of a mixture of gas-atomized glassy powders and ductile α-brass powders. The conductivity of the BMG composite can be well modeled by the percolation theory and the critical percolation threshold volume of the high-conductive brass phase was estimated to be about 10%. It was found that the short irregular brass fibers can dramatically reduce the resistivity of the BMG, leading to an improved material with both high strength and good conductivity for functional applications.

  18. The Effect of Nano-Morphology Modification Using an Amphiphilic Polymer on the Proton Conductivity of Composite Membrane for a Polymer Membrane-Based Fuel Cell.

    PubMed

    Roh, Sung-Hee; Rho, Seon-Gyun; Kim, Sang-Chai; Kim, Ju-Young; Jung, Ho-Young

    2016-02-01

    The effect of morphology modification using an amphiphilic polymer on the proton conductivity of composite membrane for a polymer membrane-based fuel cell was investigated. The proton conductivity of each composite membrane was analyzed by the electrochemical impedance spectroscopy (EIS). The morphological change was confirmed by scanning electron microscope (SEM). In the composite membrane, the proton conductive component was sulfonated poly(ether ether ketone) (sPEEK), while the nonconductive component was poly(vinylidenedifluoride) and the amphiphilic polymer as a compatibilizer was urethane acrylate non-ionomer (UAN). UAN as a compatibilizer improved the interfacial stability between sPEEK and PVdF polymers, even though two polymers were apparently immiscible. The homogeneous distribution of sPEEK and PVdF domains in the composite membrane was obtained with the introduction of UAN due to the amphiphilicity. Therefore, it was found that the proton conductivity of the composite membrane increased with the incorporation of UAN as a compatibilizer.

  19. SPEEK/PVDF/PES Composite as Alternative Proton Exchange Membrane for Vanadium Redox Flow Batteries

    NASA Astrophysics Data System (ADS)

    Fu, Zhimin; Liu, Jinying; Liu, Qifeng

    2016-01-01

    A membrane consisting of a blend of sulfonated poly(ether ether ketone) (SPEEK), poly(vinylidene fluoride) (PVDF), and poly(ether sulfone) (PES) has been fabricated and used as an ion exchange membrane for application in vanadium redox flow batteries (VRBs). The vanadium ion permeability of the SPEEK/PVDF/PES membrane was one order of magnitude lower than that of Nafion 117 membrane. The low-cost composite membrane exhibited better performance than Nafion 117 membrane at the same operating condition. A VRB single cell with SPEEK/PVDF/PES membrane showed significantly lower capacity loss, higher coulombic efficiency (>95%), and higher energy efficiency (>82%) compared with Nafion 117 membrane. In the self-discharge test, the duration of the cell with the SPEEK/PVDF/PES membrane was nearly two times longer than that with Nafion 117 membrane. Considering these good properties and its low cost, SPEEK/PVDF/PES membrane is expected to have excellent commercial prospects as an ion exchange membrane for VRB systems.

  20. Physically Gelled Room-Temperature Ionic Liquid-Based Composite Membranes for CO2/N-2 Separation: Effect of Composition and Thickness on Membrane Properties and Performance

    SciTech Connect

    Nguyen, PT; Voss, BA; Wiesenauer, EF; Gin, DL; Nobe, RD

    2013-07-03

    An aspartame-based, low molecular-weight organic gelator (LMOG) was used to form melt-infused and composite membranes with two different imidazolium-based room-temperature ionic liquids (RTILs) for CO2 separation from N-2. Previous work demonstrated that LMOGs can gel RTILs at low, loading levels, and this aspartame-based LMOG was selected because it has been reported to gel a large number of RTILs. The imidazolium-based RTILs were used because of their inherent good properties for CO2/light gas separations. Analysis of the resulting bulk RTIL/LMOG physical gels showed that these materials have high sol-gel transition temperatures (ca. 135 degrees C) suitable for flue gas applications. Gas permeabilities and burst pressure measurements of thick, melt infused membranes revealed a trade-off between high CO2 permeabilities and good mechanical stability as a function of the LMOG loading. Defect-free, composite membranes of the gelled RTILs were successfully fabricated by choosing an appropriate porous membrane support (hydrophobic PTFE) using a suitable coating technique (roller coating). The thicknesses of the applied composite gel layers ranged from 10.3 to 20.7 mu m, which represents an order of magnitude decrease in active layer thickness, compared to the original melt-infused gel RTIL membranes.

  1. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint metal/composite semi-constrained cemented prosthesis is a device intended to be implanted to replace...

  2. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint metal/composite semi-constrained cemented prosthesis is a device intended to be implanted to replace...

  3. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint metal/composite semi-constrained cemented prosthesis is a device intended to be implanted to replace...

  4. 21 CFR 888.3500 - Knee joint femorotibial metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint femorotibial metal/composite semi... § 888.3500 Knee joint femorotibial metal/composite semi-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite semi-constrained cemented prosthesis is a...

  5. 21 CFR 888.3490 - Knee joint femorotibial metal/composite non-constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint femorotibial metal/composite non... § 888.3490 Knee joint femorotibial metal/composite non-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite non-constrained cemented prosthesis is a...

  6. 21 CFR 888.3490 - Knee joint femorotibial metal/composite non-constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Knee joint femorotibial metal/composite non... § 888.3490 Knee joint femorotibial metal/composite non-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite non-constrained cemented prosthesis is a...

  7. 21 CFR 888.3490 - Knee joint femorotibial metal/composite non-constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Knee joint femorotibial metal/composite non... § 888.3490 Knee joint femorotibial metal/composite non-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite non-constrained cemented prosthesis is a...

  8. 21 CFR 888.3500 - Knee joint femorotibial metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Knee joint femorotibial metal/composite semi... § 888.3500 Knee joint femorotibial metal/composite semi-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite semi-constrained cemented prosthesis is a...

  9. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint metal/composite semi-constrained cemented prosthesis is a device intended to be implanted to replace...

  10. 21 CFR 888.3500 - Knee joint femorotibial metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Knee joint femorotibial metal/composite semi... § 888.3500 Knee joint femorotibial metal/composite semi-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite semi-constrained cemented prosthesis is a...

  11. 21 CFR 888.3500 - Knee joint femorotibial metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Knee joint femorotibial metal/composite semi... § 888.3500 Knee joint femorotibial metal/composite semi-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite semi-constrained cemented prosthesis is a...

  12. 21 CFR 888.3490 - Knee joint femorotibial metal/composite non-constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Knee joint femorotibial metal/composite non... § 888.3490 Knee joint femorotibial metal/composite non-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite non-constrained cemented prosthesis is a...

  13. 21 CFR 888.3490 - Knee joint femorotibial metal/composite non-constrained cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Knee joint femorotibial metal/composite non... § 888.3490 Knee joint femorotibial metal/composite non-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite non-constrained cemented prosthesis is a...

  14. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ankle joint metal/composite semi-constrained... Ankle joint metal/composite semi-constrained cemented prosthesis. (a) Identification. An ankle joint metal/composite semi-constrained cemented prosthesis is a device intended to be implanted to replace...

  15. 21 CFR 888.3500 - Knee joint femorotibial metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Knee joint femorotibial metal/composite semi... § 888.3500 Knee joint femorotibial metal/composite semi-constrained cemented prosthesis. (a) Identification. A knee joint femorotibial metal/composite semi-constrained cemented prosthesis is a...

  16. Highly hydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles.

    PubMed

    Tiraferri, Alberto; Kang, Yan; Giannelis, Emmanuel P; Elimelech, Menachem

    2012-09-26

    Thin-film composite polyamide membranes are state-of-the-art materials for membrane-based water purification and desalination processes, which require both high rejection of contaminants and high water permeabilities. However, these membranes are prone to fouling when processing natural waters and wastewaters, because of the inherent surface physicochemical properties of polyamides. The present work demonstrates the fabrication of forward osmosis polyamide membranes with optimized surface properties via facile and scalable functionalization with fine-tuned nanoparticles. Silica nanoparticles are coated with superhydrophilic ligands possessing functional groups that impart stability to the nanoparticles and bind irreversibly to the native carboxyl moieties on the membrane selective layer. The tightly tethered layer of nanoparticles tailors the surface chemistry of the novel composite membrane without altering the morphology or water/solute permeabilities of the membrane selective layer. Surface characterization and interfacial energy analysis confirm that highly hydrophilic and wettable membrane surfaces are successfully attained. Lower intermolecular adhesion forces are measured between the new membrane materials and model organic foulants, indicating the presence of a bound hydration layer at the polyamide membrane surface that creates a barrier for foulant adhesion.

  17. Method of thermal strain hysteresis reduction in metal matrix composites

    NASA Technical Reports Server (NTRS)

    Dries, Gregory A. (Inventor); Tompkins, Stephen S. (Inventor)

    1987-01-01

    A method is disclosed for treating graphite reinforced metal matrix composites so as to eliminate thermal strain hysteresis and impart dimensional stability through a large thermal cycle. The method is applied to the composite post fabrication and is effective on metal matrix materials using graphite fibers manufactured by both the hot roll bonding and diffusion bonding techniques. The method consists of first heat treating the material in a solution anneal oven followed by a water quench and then subjecting the material to a cryogenic treatment in a cryogenic oven. This heat treatment and cryogenic stress reflief is effective in imparting a dimensional stability and reduced thermal strain hysteresis in the material over a -250.degree. F. to +250.degree. F. thermal cycle.

  18. Metal matrix composite fuel for space radioisotope energy sources

    NASA Astrophysics Data System (ADS)

    Williams, H. R.; Ning, H.; Reece, M. J.; Ambrosi, R. M.; Bannister, N. P.; Stephenson, K.

    2013-02-01

    Radioisotope fuels produce heat that can be used for spacecraft thermal control or converted to electricity. They must retain integrity in the event of destruction or atmospheric entry of the parent spacecraft. Addition of a metal matrix to the actinide oxide could yield a more robust fuel form. Neodymium (III) oxide (Nd2O3) - niobium metal matrix composites were produced using Spark Plasma Sintering; Nd2O3 is a non-radioactive surrogate for americium (III) oxide (Am2O3). Two compositions, 70 and 50 wt% Nd2O3, were mechanically tested under equibiaxial (ring-on-ring) flexure according to ASTM C1499. The addition of the niobium matrix increased the mean flexural strength by a factor of about 2 compared to typical ceramic nuclear fuels, and significantly increased the Weibull modulus to over 20. These improved mechanical properties could result in reduced fuel dispersion in severe accidents and improved safety of space radioisotope power systems.

  19. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    SciTech Connect

    Kim, Hyong June

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  20. Comparison of biofouling mechanisms between cellulose triacetate (CTA) and thin-film composite (TFC) polyamide forward osmosis membranes in osmotic membrane bioreactors.

    PubMed

    Wang, Xinhua; Zhao, Yanxiao; Yuan, Bo; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-02-01

    There are two types of popular forward osmosis (FO) membrane materials applied for researches on FO process, cellulose triacetate (CTA) and thin film composite (TFC) polyamide. However, performance and fouling mechanisms of commercial TFC FO membrane in osmotic membrane bioreactors (OMBRs) are still unknown. In current study, its biofouling behaviors in OMBRs were investigated and further compared to the CTA FO membrane. The results indicated that β-D-glucopyranose polysaccharides and microorganisms accounted for approximately 77% of total biovolume on the CTA FO membrane while β-D-glucopyranose polysaccharides (biovolume ratio of 81.1%) were the only dominant biofoulants on the TFC FO membrane. The analyses on the biofouling structure implied that a tighter biofouling layer with a larger biovolume was formed on the CTA FO membrane. The differences in biofouling behaviors including biofoulants composition and biofouling structure between CTA and TFC FO membranes were attributed to different membrane surface properties.

  1. Metal matrix coated fiber composites and the methods of manufacturing such composites

    DOEpatents

    Weeks, J.K. Jr.; Gensse, C.

    1993-09-14

    A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials. 8 figures.

  2. Interface Characteristics and the Mechanical Properties of Metal Matrix Composites.

    DTIC Science & Technology

    1987-09-28

    oxide were identified to most probably be y - A120 3 or the MgAI20 4 type spinel. Details are given in Appendix K. Summary -. The research reported ...Zecas aT Austit. INTERFACE CHARACTERISTICS AND THE MECHANICAL PROPERTIES OF METAL MATRIX COMPOSITES UTCMSE-87-3 Office of Naval Research Technical Report ...THIS PAGE (When Date Entered) READ INSTRUCTIONSREPORT DOCUMENTATION PAGE I RE COSPLETIOR~BEFORE MPLETING FORM VI REPORT NUMBER 2. GOVT ACCESSION NO., 3

  3. Active Metal Brazing of Carbon-Carbon Composites to Titanium

    NASA Technical Reports Server (NTRS)

    Singh, M.; Shpargel, T. P.; Morscher, G.; Asthana, R.

    2004-01-01

    The Ti-metal/C-C composite joints were formed by reactive brazing with three commercial brazes, namely, Cu-ABA, TiCuNi, and TiCuSil. The joint microstructures were examined using optical microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). The results of the microstructure analysis indicate solute redistribution across the joint which led to good wetting, spreading, and metallurgical bond formation via interdiffusion.

  4. Elucidating the Composition and Distribution of Trace Metals in Corals

    NASA Astrophysics Data System (ADS)

    Farfan, G.; Webb, S. M.; Apprill, A.; Hansel, C. M.

    2014-12-01

    Coral reefs host a plethora of marine life and thereby provide a wealth of aesthetic and economic benefits to coastal countries. Anthropogenic influences, including local coastal water contamination, however threaten the health of these delicate ecosystems. Metal incorporation into carbonate minerals, the backbone of coral reefs, is known to have a large yet variable impact on carbonate structure and solubility. Yet, trace metal influences on the structure, porosity, composition, and solubility of coral skeletons is largely unknown. Here, we coupled synchrotron-based micro-X-ray fluorescence (u-XRF) mapping and X-ray absorption near edge structure (XANES) spectroscopy with micro-X-ray diffraction (XRD) to explore the distribution and speciation of trace metals associated with corals and their impact on the carbonate structure of corals obtained from reefs varying in anthropogenic influence - Florida Keys, FL USA and the Federated States of Micronesia. Iron and copper were the most abundant metals in the biological tissue, while in some areas zinc was observed in the tissue, overlapping with the skeleton. Trace metals were not detectable in the aragonite skeletons; in fact, the distributions of Ca and Fe were anti-correlated. XANES spectra show that the iron is primarily Fe(III), likely as the poorly crystalline iron oxide ferrihydrite structure or trapped within ferretin proteins. The same trace metals were observed in corals of different species and from different environments. This in situ investigation corroborates previous studies that corals tend to incorporate iron into the biological components but not into the aragonite skeleton. Given the dominant partitioning of metals within the biological tissue rather than the coral skeleton, the specific carbon molecules responsible for metal attenuation and their fate under changing geochemical conditions and following coral death require exploration.

  5. Refractory metal alloys and composites for space nuclear power systems

    SciTech Connect

    Titran, R.H.; Stephens, J.R.; Petrasek, D.W.

    1988-01-01

    Space power requirements for future NASA and other United States missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary power source to meet these high levels of electrical demand. One method to achieve maximum efficiency is to operate the power supply, energy conversion system, and related components at relatively high temperatures. For systems now in the planning stages, design temperatures range from 1300 K for the immediate future to as high as 1700 K for the advanced systems. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide base line information for space power systems in the 1900's and the 21st century. Special emphasis is focused on the refractory metal alloys of niobium and on the refractory metal composites which utilize tungsten alloy wire for reinforcement. Basic research on the creep and creep-rupture properties of wires, matrices, and composites will be discussed. 20 refs., 27 figs., 1 tab.

  6. Refractory metal alloys and composites for space nuclear power systems

    NASA Technical Reports Server (NTRS)

    Titran, Robert H.; Stephens, Joseph R.; Petrasek, Donald W.

    1988-01-01

    Space power requirements for future NASA and other U.S. missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the Space Shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary power source to meet these high levels of electrical demand. One method to achieve maximum efficiency is to operate the power supply, energy conservation system, and related components at relatively high temperatures. For systems now in the planning stages, design temperatures range from 1300 K for the immediate future to as high as 1700 K for the advanced systems. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide baseline information for space power systems in the 1900's and the 21st century. Special emphasis is focused on the refractory metal alloys of niobium and on the refractory metal composites which utilize tungsten alloy wires for reinforcement. Basic research on the creep and creep-rupture properties of wires, matrices, and composites are discussed.

  7. Influence of inorganic complexes on the transport of trace metals through permeation liquid membrane.

    PubMed

    Bayen, Stéphane; Gunkel-Grillon, Peggy; Worms, Isabelle; Martin, Michel; Buffle, Jacques

    2009-07-30

    Under specific conditions (pH, concentrations), trace metals may form, with environmental inorganic ligands, neutral complexes which, in principle, might diffuse passively through biological membranes or influence the response of (bio)analytical sensors for trace metals based on permeation liquid membrane (PLM). In this study, metal (Cu, Cd, Pb) transport through the planar PLM device was evaluated in the presence of major environmental inorganic ligands such as sulfate, carbonate and chloride under conditions where neutral complexes may be formed (up to 73% of neutral metal complex in the solution). In the presence of sulfate, comparison of predicted and experimental PLM fluxes of Cu, Pb and Cd, suggests that passive transport of neutral sulfate-metal complexes does not occur. This was confirmed by comparing fluxes in the presence and absence of carrier. In the presence of carbonate (for Cd, Cu and Pb) and chloride (for Pb and Cd), however, experimental PLM fluxes were greater than predicted (up to 4 and 25 times in the presence of carbonate and chloride, respectively), but experiments in the absence of carrier in the membrane revealed that no passive transport of neutral complexes (MCl(2) or MCO(3)) occurs through PLM. A possible mechanism is discussed. In parallel to the experiments with PLM, the influence of carbonate on the internalization fluxes of Cu(II) and Pb(II) by the freshwater algae, Chlamydomonas reinhardtii, was assessed. Similarly to the results of PLM, the fluxes of these two metals were larger than expected (based on the free metal ion activity model). Thus, even though PLM and bioaccumulation mechanisms are certainly different, similar unexpected behaviours occur for the metal transport through the PLM and biological membrane of C. reinhardtii, in the presence of carbonate.

  8. Formation and growth of lithium metal dendrites through solid block copolymer membranes

    NASA Astrophysics Data System (ADS)

    Harry, Katherine; Higa, Kenneth; Balsara, Nitash

    Dendrite growth from lithium metal in electrochemical systems is the primary problem that precludes the wide use of lithium metal as an anode material. While polystyrene-block-poly(ethylene oxide) copolymer electrolytes extend cell life by suppressing dendrite growth, dendrites eventually do grow and the batteries fail by a short-circuit. In situ hard X-ray microtomography experiments coupled with stress simulations shed light on the formation and growth of dendritic structures through stiff solid polymer electrolyte membranes.

  9. Microfluidic free-flow zone electrophoresis and isotachophoresis using carbon black nano-composite PDMS sidewall membranes.

    PubMed

    Fu, Xiaotong; Mavrogiannis, Nicholas; Ibo, Markela; Crivellari, Francesca; Gagnon, Zachary R

    2017-01-01

    We present a new type of free-flow electrophoresis (FFE) device for performing on-chip microfluidic isotachophoresis and zone electrophoresis. FFE is performed using metal gallium electrodes, which are isolated from a main microfluidic flow channel using thin micron-scale polydimethylsiloxane/carbon black (PDMS/CB) composite membranes integrated directly into the sidewalls of the microfluidic channel. The thin membrane allows for field penetration and effective electrophoresis, but serves to prevent bubble generation at the electrodes from electrolysis. We experimentally demonstrate the ability to use this platform to perform on-chip free-flow electrophoretic separation and isotachophoretic concentration. Due to the small size and simple fabrication procedure, this PDMS/CB platform could be used as a part of an on-chip upstream sample preparation toolkit for portable microfluidic diagnostic applications.

  10. Composite Nafion/sulfonated zirconia membranes: effect of the filler surface properties on proton transport characteristics

    PubMed Central

    D’Epifanio, Alessandra; Navarra, Maria Assunta; Weise, F. Christoph; Mecheri, Barbara; Farrington, Jaime; Licoccia, Silvia; Greenbaum, Steve

    2009-01-01

    Due to their strong acidity and water affinity, sulfated zirconia nanoparticles were evaluated as inorganic additives in the formation of composite Nafion-based membranes. Two types of sulfated zirconia were obtained according to the preparation experimental conditions. Sulfated zirconia-doped Nafion membranes were prepared by a casting procedure. The properties of the composite membranes were compared with those of an unfilled Nafion membrane obtained by the same preparation method. The water uptake, measured at room temperature in a wide relative humidity range, was higher for the composite membranes, this confirming the hydrophilic nature of the selected additives. The membrane doped by zirconia particles having the highest sulphate group concentration showed the highest water diffusion coefficient in the whole range of temperature and relative humidity investigated due to the presence of SO42− providing extra acid sites for water diffusion. The proton diffusivity calculated from impedance spectroscopy measurements was compared with water self diffusion coefficients measured by NMR Spectroscopy. The difference between proton and water diffusivity became significant only at high humidification levels, highlighting the role of water in the intermolecular proton transfer mechanism. Finally, great improvements were found when using the composite membrane as electrolyte in a fuel cell working at very low relative humidity. PMID:20209115

  11. Electrospun PDLLA/PLGA composite membranes for potential application in guided tissue regeneration.

    PubMed

    Zhang, Ershuai; Zhu, Chuanshun; Yang, Jun; Sun, Hong; Zhang, Xiaomin; Li, Suhua; Wang, Yonglan; Sun, Lu; Yao, Fanglian

    2016-01-01

    With the aim to explore a membrane system with appropriate degradation rate and excellent cell-occlusiveness for guided tissue regeneration (GTR), a series of poly(D, L-lactic acid) (PDLLA)/poly(D, L-lactic-co-glycolic acid) (PLGA) (100/0, 70/30, 50/50, 30/70, 0/100, w/w) composite membranes were fabricated via electrospinning. The fabricated membranes were evaluated by morphological characterization, water contact angle measurement and tensile test. In vitro degradation was characterized in terms of the weight loss and the morphological change. Moreover, in vitro cytologic research revealed that PDLLA/PLGA composite membranes could efficiently inhibit the infiltration of 293 T cells. Finally, subcutaneous implant test on SD rat in vivo showed that PDLLA/PLGA (70/30, 50/50) composite membranes could function well as a physical barrier to prevent cellular infiltration within 13 weeks. These results suggested that electrospun PDLLA/PLGA (50/50) composite membranes could serve as a promising barrier membrane for guided tissue regeneration due to suitable biodegradability, preferable mechanical properties and excellent cellular shielding effects.

  12. Actomyosin dynamics drive local membrane component organization in an in vitro active composite layer

    PubMed Central

    Husain, Kabir; Iljazi, Elda; Bhat, Abrar; Bieling, Peter; Mullins, R. Dyche; Rao, Madan; Mayor, Satyajit

    2016-01-01

    The surface of a living cell provides a platform for receptor signaling, protein sorting, transport, and endocytosis, whose regulation requires the local control of membrane organization. Previous work has revealed a role for dynamic actomyosin in membrane protein and lipid organization, suggesting that the cell surface behaves as an active composite composed of a fluid bilayer and a thin film of active actomyosin. We reconstitute an analogous system in vitro that consists of a fluid lipid bilayer coupled via membrane-associated actin-binding proteins to dynamic actin filaments and myosin motors. Upon complete consumption of ATP, this system settles into distinct phases of actin organization, namely bundled filaments, linked apolar asters, and a lattice of polar asters. These depend on actin concentration, filament length, and actin/myosin ratio. During formation of the polar aster phase, advection of the self-organizing actomyosin network drives transient clustering of actin-associated membrane components. Regeneration of ATP supports a constitutively remodeling actomyosin state, which in turn drives active fluctuations of coupled membrane components, resembling those observed at the cell surface. In a multicomponent membrane bilayer, this remodeling actomyosin layer contributes to changes in the extent and dynamics of phase-segregating domains. These results show how local membrane composition can be driven by active processes arising from actomyosin, highlighting the fundamental basis of the active composite model of the cell surface, and indicate its relevance to the study of membrane organization. PMID:26929326

  13. Electrospun Nafion®/Polyphenylsulfone composite membranes for regenerative Hydrogen bromine fuel cells

    DOE PAGES

    Park, Jun; Wycisk, Ryszard; Pintauro, Peter N.; ...

    2016-02-29

    Here, the regenerative H2/Br2-HBr fuel cell, utilizing an oxidant solution of Br2 in aqueous HBr, shows a number of benefits for grid-scale electricity storage. The membrane-electrode assembly, a key component of a fuel cell, contains a proton-conducting membrane, typically based on the perfluorosulfonic acid (PFSA) ionomer. Unfortunately, the high cost of PFSA membranes and their relatively high bromine crossover are serious drawbacks. Nanofiber composite membranes can overcome these limitations. In this work, composite membranes were prepared from electrospun dual-fiber mats containing Nafion® PFSA ionomer for facile proton transport and an uncharged polymer, polyphenylsulfone (PPSU), for mechanical reinforcement, and swelling control.more » After electrospinning, Nafion/PPSU mats were converted into composite membranes by softening the PPSU fibers, through exposure to chloroform vapor, thus filling the voids between ionomer nanofibers. It was demonstrated that the relative membrane selectivity, referenced to Nafion® 115, increased with increasing PPSU content, e.g., a selectivity of 11 at 25 vol% of Nafion fibers. H2-Br2 fuel cell power output with a 65 m thick membrane containing 55 vol% Nafion fibers was somewhat better than that of a 150 m Nafion® 115 reference, but its cost advantage due to a four-fold decrease in PFSA content and a lower bromine species crossover make it an attractive candidate for use in H2/Br2-HBr systems.« less

  14. Self-sterilized composite membranes of cellulose acetate/polyethylene glycol for water desalination.

    PubMed

    Ahmad, Adnan; Jamshed, Fahad; Riaz, Tabinda; Gul, Sabad-E-; Waheed, Sidra; Sabir, Aneela; AlAnezi, Adnan Alhathal; Adrees, Muhammad; Jamil, Tahir

    2016-09-20

    Cellulose acetate/Polyethylene glycol-600 composite membranes were fabricated by two step phase inversion procedure and modified by in-situ reduction of silver nitrate. FTIR spectra demonstrated the existence of functional groups for bonding of silver with oxygen at 370cm(-1), 535cm(-1). The XRD diffractogram indicates characteristic peaks at 2θ values of 38.10°, 44.30°, 64.40°, and 77.30° which confirm the successful incorporation of silver within matrix of composite membranes. The morphology of composite membranes with appearances of spongy voids was exemplified from the scanning electron microscope. The atomic force microscopy was used to determine the increase in the surface roughness of the membranes. The increase in hydrophilicity, measured through contact angle, is rendered to the embedment of silver. The modification of membranes increased the flux from 0.80 to 0.95L/hr.m(2). The resulting membranes have outstanding ability to fight against gram negative Escherichia Coli and Bacillus Sabtilus. The novel cellulose acetate/polyethylene glycol membranes customized with silver have paved the path for evolution of axenic membranes.

  15. Erythrocyte membrane composition in patients with primary hypercholesterolemia.

    PubMed

    Vayá, A; Martínez Triguero, M; Réganon, E; Vila, V; Martínez Sales, V; Solá, E; Hernández Mijares, A; Ricart, A

    2008-01-01

    There are conflicting results regarding the erythrocyte membrane cholesterol and phospholipid content in patients with primary hypercholesterolemia (PHC), due to methodological problems in obtaining haemoglobin-free ghosts. At the same time, the different units used and the fact that the cholesterol and phospholipids are not expressed in relation with integral protein membrane content, produces contradictory results. We have analysed in 33 patients with PHC (12 male, 31 female) aged 43+/-12 years and in 33 healthy normolipaemic volunteers (9 male, 24 female) aged 43+/-13 years plasma lipids, along with, erythrocyte membrane cholesterol, phospholipids and integral proteins. PHC patients showed increased erythrocyte membrane cholesterol: 0.36+/-0.15 mg/mg when compared with controls: 0.29+/-0.75 mg/mg; p=0.018. Phospholipid membrane content, although higher in the cases, did not reach statistical significance (PHC patients: 0.38+/-0.15 mg/mg vs. 0.33+/-0.72 mg/mg; p=0.098). The cholesterol/phospholipids ratio (Chol/Ph) was 0.99+/-0.22 in PHC patients versus 0.92+/-0.28 in controls; p=0.127. Our results suggest that there is a slight increase in erythrocyte membrane cholesterol in patients with PHC. Given the increasing importance of erythrocyte membrane cholesterol in the stability of the atheroma plaque due its possible contribution to the clinical signs of ischaemic heart disease, it seems relevant to determine this parameter in risk populations. Therefore, a simple and reproducible method needs to be standardised which would enable comparisons between laboratories and facilitate further studies aimed to it as a marker of acute coronary syndromes.

  16. Composites PVDF-TrFE/BT used as bioactive membranes for enhancing bone regeneration

    NASA Astrophysics Data System (ADS)

    Gimenes, Rossano; Zaghete, Maria A.; Bertolini, Marcio; Varela, Jose A.; Coelho, Luciane O.; Silva, Nelson F., Jr.

    2004-07-01

    In this paper a piezoelectric composite membranes were developed for charge generator to promoter bone regeneration on defects sites. Is known that the osteogenesis process is induced by interactions between biological mechanisms and electrical phenomena. The membranes were prepared by mixing Barium Titanate (BT) powders and PVDF-TrFE (PVDF:TrFE = 60:40 mol%) on dimethylformamide medium. This precursor solution was dried and crystallized at 100oC for 12 hours. Composites membranes were obtained by following methods: solvent casting (SC), spincoating (SP), solvent extraction by water addition (WS) and hot pressing (HP). The microstructural analysis performed by SEM showed connectivity type 3-0 and 3-1 with high homogeneity for samples of ceramic volume fraction major than 0.50. Powder agglomerates within the polymer matrix was evidenced were observed for composites with the BT volume fraction major than 40%. The composite of ceramic fraction of 0.55 presented the best values of remanent polarization (~33mC/cm2), but the flexibility of these composites with the larger ceramic fraction was significantly affected. For in vivo evaluation PVDF-TrFE/BT 90/10 membranes with 3cm larger were longitudinally implanted under tibiae of male rabbit. After 21 days the animals were sacrificed. By histological analyses were observed neo formed bone with a high mitotic activity. In the interface bone-membrane was evidenced a pronounced callus formation. These results encourage further applications of these membranes in bone-repair process.

  17. Development and characterization of composite YSZ-PEI electrophoretically deposited membrane for Li-ion battery.

    PubMed

    Hadar, R; Golodnitsky, D; Mazor, H; Ripenbein, T; Ardel, G; Barkay, Z; Gladkich, A; Peled, E

    2013-02-14

    In this work, the electrophoretic-deposition (EPD) method was used to fabricate pristine and composite ceramic-polymer membranes for application in planar and 3D microbattery configurations. The major focus was on the effect of polyethyleneimine additive on the morphology, composition, and electrochemical properties of the membrane. The ionic conductivity, cycleability, and charge/discharge behavior of planar LiFePO(4)/Li cells comprising composite porous YSZ-based membrane with impregnated LiPF(6) EC:DEC electrolyte were found to be similar to the cells with commercial Celgard membrane. Conformal EPD coating of the electrode materials by a thin-film ceramic separator is advantageous for high-power operation and safety of batteries.

  18. Synthesis and characterization of chitosan/ZnO nanoparticle composite membranes.

    PubMed

    Li, Li-Hua; Deng, Jian-Cheng; Deng, Hui-Ren; Liu, Zi-Ling; Xin, Ling

    2010-05-27

    Novel chitosan/ZnO nanoparticle (CS/nano-ZnO) composite membranes were prepared via the method of sol-cast transformation and studied by UV-vis absorption spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray fluorescence spectrometry (EDX). The characterization revealed that ZnO nanoparticles dispersed homogeneously within the chitosan matrix. The mechanical and antibacterial properties of the product were investigated. The results showed that the ZnO content had an effect on the mechanical properties of CS/nano-ZnO composite membranes, and that the antibacterial activities of CS membranes for Bacillus subtilis, Escherichia coli, and Staphylococcus aureus were enhanced by the incorporation of ZnO. Further, CS/nano-ZnO composite membranes with 6-10 wt% ZnO exhibited high antibacterial activities.

  19. Ultra-thin-polysiloxane-film-composite membranes for the optimisation of amperometric oxidase enzyme electrodes.

    PubMed

    Myler, S; Collyer, S D; Bridge, K A; Higson, S P J

    2002-01-01

    An outer ultra-thin-polydimethyldichlorosiloxane film composite membrane has been used as the outer covering barrier in an amperometric glucose oxidase enzyme electrode biosensor. The composite membrane was formed via the condensation polymerisation of dimethyldichlorosilane at the surface of a host porous alumina membrane. Homogeneous polydimethyldichlorosiloxane films of <100 nm thickness acted as effective substrate diffusional barriers and were supported by the underlying porous alumina surface. Glucose and oxygen permeability coefficients were determined using diffusion chamber apparatus. Polysiloxane composite membranes were found to offer some screening functionality towards anionic biological interferents such as ascorbate. On exposure to blood an approximate 25% signal drift was observed during the first 2 h exposure to blood; after this time responses remained almost stable. Whole blood glucose determinations showed a close correlation (r(2)=0.98) to analyses performed via standard hospital analyses.

  20. Refractory metal alloys and composites for space power systems

    NASA Technical Reports Server (NTRS)

    Stephens, R.; Petrasek, D. W.; Titran, R. H.

    1990-01-01

    Results are presented on recent studies of refractory-metal-alloy and refractory-metal-composite technologies for space power systems, with emphasis on work performed at the Lewis Research Center in support of the Ground Engineering System (GES) for the SP-100 reactor. Special attention is given to the mechanical properties of alloys with compositions Nb-1Zr and Nb-0.1Zr-0.1C (the PWC-11 alloy) and to advanced fiber-reinforced composites. The results to date indicate that, for the GES at a power level of about 100 kWe, the PWC-11 has attractive creep properties that will extend the capabilities of the SP-100 reactor compared to a similar system fabricated from Nb-1Zr. On the other hand, tungsten-reinforced Nb-1Zr composites were found to provide a ten-fold and four-fold creep strength over Nb-1Zr and PWC-11, respectively, at 1400 to 1500 K.

  1. Orientation and dynamics of melittin in membranes of varying composition utilizing NBD fluorescence.

    PubMed

    Raghuraman, H; Chattopadhyay, Amitabha

    2007-02-15

    Melittin is a cationic hemolytic peptide isolated from the European honey bee, Apis mellifera. The organization of membrane-bound melittin has earlier been shown to be dependent on the physical state and composition of membranes. In this study, we covalently labeled the N-terminal (Gly-1) and Lys-7 of melittin with an environment-sensitive fluorescent probe, the NBD group, to monitor the influence of negatively charged lipids and cholesterol on the organization and dynamics of membrane-bound melittin. Our results show that the NBD group of melittin labeled at its N-terminal end does not exhibit red edge excitation shift in DOPC and DOPC/DOPG membranes, whereas the NBD group of melittin labeled at Lys-7 exhibits REES of approximately 8 nm. This could be attributed to difference in membrane microenvironment experienced by the NBD groups in these analogs. Interestingly, the membrane environment of the NBD groups is sensitive to the presence of cholesterol, which is supported by time-resolved fluorescence measurements. Importantly, the orientation of melittin is found to be parallel to the membrane surface as determined by membrane penetration depth analysis using the parallax method in all cases. Our results constitute the first report to our knowledge describing the orientation of melittin in cholesterol-containing membranes. These results assume significance in the overall context of the role of membrane lipids in the orientation and function of membrane proteins and peptides.

  2. Self-diffusion of ions in Nafion-117 membrane having mixed ionic composition.

    PubMed

    Chaudhury, Sanhita; Agarwal, Chhavi; Pandey, A K; Goswami, A

    2012-02-09

    The self-diffusion coefficients (SDCs) of Na(+), Cs(+), and Ba(2+) have been determined in Nafion-117 membrane having mixed cationic compositions. Membranes with different proportions of Na(+)-Cs(+), Cs(+)-Ba(2+), Na(+)-Ba(2+), and Ag(+)-Ba(2+) cations have been prepared by equilibrating with solutions containing different ratios of these cations. The SDCs of the cations (D(Na), D(Cs), D(Ba)) and the ionic compositions of the membrane have been determined using a radiotracer method. For the Na-Cs and Cs-Ba systems, the SDCs of the cations have been found to be independent of the ionic compositions of the membrane. In the case of the Na-Ba system, D(Na) does not change with ionic composition, while D(Ba) has been found to be strongly dependent on the ionic composition of the membrane and decreases continuously with increasing Na(+) content in the membrane. Similar results have also been obtained for D(Ba) in the case of the Ag-Ba system. The specific conductivities (κ(imp)) of the membrane in mixed cationic forms have also been obtained from ac impedance measurement and compared with that (κ(cal)) calculated from the SDC data. For the Na-Ba system, the increment of κ(imp) with increase in the Na(+) content of the membrane has been found to be parabolic, whereas for the Na-Cs system the increment is linear. The reason behind the different behaviors for different types of ionic systems has been qualitatively explained based on different transport pathways of the cations in the membrane.

  3. Fiber shape effects on metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Brown, H. C.; Lee, H.-J.; Chamis, C. C.

    1992-01-01

    The effects of different fiber shapes on the behavior of a SiC/Ti-15 metal matrix composite is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers is used in the analysis. The model is employed to represent five different fiber shapes: a circle, an ellipse, a kidney, and two different cross shapes. The distribution of microstresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis for the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes and assess their potential benefits. No clear benefits result from different fiber shapes though there are some increases/decreases in isolated properties.

  4. The mechanical behavior of a hybrid metal matrix composite

    NASA Astrophysics Data System (ADS)

    Zok, F.; Jansson, S.; Evans, A. G.; Nardone, V.

    1991-09-01

    The mechanical behavior of a unidirectionally reinforced hybrid metal matrix composite in two different states has been studied: one with a “weakly bonded” interface and the other with a “strong” interface. Similarities and contrasts in mechanical behavior have been related to the properties of the interface. The longitudinal tensile strength and the crack growth initiation resistance are found to be insensitive to the condition of the interface. However, the material with the “weak” interface exhibits extensive debonding, resulting in a steeply increasing resistance curve and a large work of rupture. Furthermore, the weak interface reduces the transverse and torsional strength of the composite. This study illustrates how the tailoring of interfacial properties can improve the mechanical performance of composites for certain structural applications.

  5. Material and structural studies of metal and polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Signorelli, R. A.; Serafini, T. T.; Johns, R. H.

    1973-01-01

    Fiber-reinforced composites and design analysis methods for these materials are being developed because of the vast potential of composites for decreasing weight and/or increasing use temperature capability in aerospace systems. These composites have potential for use in airbreathing engine components as well as aeronautical and space vehicle structures. Refractory wire-superalloy composites for use up to 2200 F or more and metal-matrix composites for lower temperature applications such as aerospace structures and turbojet fan and compressor blades are under investigation and are discussed. The development of a number of resin systems, including the polyimides and polyphenylquinoxalines, is described and their potential for use at temperatures approaching 315 C (600 F) is indicated. Various molecular modifications that improve processability and/or increase thermal and oxidative resistance of the resins are also described. Structural analysis methods are discussed for determining the stresses and deformations in complex composite systems. Consideration is also given to residual stresses resulting from the curing process and to the foreign object damage problem in fan blade applications.

  6. Diffusion analysis for two-phase metal-matrix composite

    NASA Technical Reports Server (NTRS)

    Tenney, D. R.

    1976-01-01

    Diffusion controlled filament matrix interaction in a metal matrix composite, where the filaments and matrix comprise a two phase binary alloy system, was mathematically modeled. The problem of a diffusion controlled, two phase moving interface by means of a one dimensional, variable grid, finite difference technique was analyzed. Concentration dependent diffusion coefficients and equilibrium solubility limits were used, and the change in filament diameter and compositional changes in the matrix were calculated as a function of exposure time at elevated temperatures. With the tungsten nickel (W-Ni) system as a model composite system, unidirectional composites containing from 0.06 to 0.44 initial filament volume fraction were modeled. Compositional changes in the matrix were calculated by superposition of the contributions from neighboring filaments. Alternate methods for determining compositional changes between first and second nearest neighbor filaments were also considered. The results show the relative importance of filament volume fraction, filament diameter, exposure temperature, and exposure time as they affect the rate and extent of filament matrix interaction.

  7. A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes

    PubMed Central

    Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A.; Sadrzadeh, Mohtada

    2016-01-01

    A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from −20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at −20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes. PMID:26924449

  8. A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes

    NASA Astrophysics Data System (ADS)

    Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A.; Sadrzadeh, Mohtada

    2016-02-01

    A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from ‑20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at ‑20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes.

  9. Effect of sterol esters on lipid composition and antioxidant status of erythrocyte membrane of hypercholesterolemic rats.

    PubMed

    Sengupta, Avery; Ghosh, Mahua

    2014-01-01

    Hypercholesterolemia is a major cause of coronary heart disease. Erythrocyte membrane is affected during hypercholesterolemia. The effect of EPA-DHA rich sterol ester and ALA rich sterol ester on erythrocyte membrane composition, osmotic fragility in normal and hypercholesterolemic rats and changes in antioxidant status of erythrocyte membrane were studied. Erythrocyte membrane composition, osmotic fragility of the membrane and antioxidant enzyme activities was analyzed. Osmotic fragility data suggested that the erythrocyte membrane of hypercholesterolemia was relatively more fragile than that of the normal rats' membrane which could be reversed with the addition of sterol esters in the diet. The increased plasma cholesterol in hypercholesterolemic rats could also be lowered by the sterol ester administration. There was also marked changes in the antioxidant enzyme activities of the erythrocyte membrane. Antioxidant enzyme levels decreased in the membrane of the hypercholesterolemic subjects were increased with the treatment of the sterol esters. The antioxidative activity of ALA rich sterol ester was better in comparison to EPA-DHA rich sterol ester. In conclusion, rat erythrocytes appear to be deformed and became more fragile in cholesterol rich blood. This deformity and fragility was partially reversed by sterol esters by virtue of their ability to lower the extent of hypercholesterolemia.

  10. Composites for removing metals and volatile organic compounds and method thereof

    DOEpatents

    Coronado, Paul R.; Coleman, Sabre J.; Reynolds, John G.

    2006-12-12

    Functionalized hydrophobic aerogel/solid support structure composites have been developed to remove metals and organic compounds from aqueous and vapor media. The targeted metals and organics are removed by passing the aqueous or vapor phase through the composite which can be in molded, granular, or powder form. The composites adsorb the metals and the organics leaving a purified aqueous or vapor stream. The species-specific adsorption occurs through specific functionalization of the aerogels tailored towards specific metals and/or organics. After adsorption, the composites can be disposed of or the targeted metals and/or organics can be reclaimed or removed and the composites recycled.

  11. Metal/Graphitic Carbon Nitride Composites: Synthesis, Structures, and Applications.

    PubMed

    Wang, Luona; Wang, Chengyin; Hu, Xiaoya; Xue, Huaiguo; Pang, Huan

    2016-12-06

    Graphitic carbon nitride (g-C3 N4 ) has been widely used in fields related to energy and materials science. However, nanostructured g-C3 N4 photocatalysts synthesized by traditional thermal polycondensation methods have the disadvantage of small specific surface areas and wide band gaps; these limit the catalytic activity and application range of g-C3 N4 . Based on the unique nanostructure of g-C3 N4 , it is a feasible method to modify g-C3 N4 with metals to design novel metal-semiconductor composites. Metals alter the photochemical properties of g-C3 N4 , in particular, narrow the band gap and expand photoabsorption into the visible range, which improves the photocatalytic performance. This review covers recent progress in metal/g-C3 N4 nanocomposites for photocatalysts, organic systems, biosensors, and so on. The aim is to summarize the synthetic methods, nanostructures, and applications of metal/g-C3 N4 nanocomposite materials, as well as discuss future research directions in these areas.

  12. Integrated Water Gas Shift Membrane Reactors Utilizing Novel, Non Precious Metal Mixed Matrix Membrane

    SciTech Connect

    Ferraris, John

    2013-09-30

    Nanoparticles of zeolitic imidazolate frameworks and other related hybrid materials were prepared by modifying published synthesis procedures by introducing bases, changing stoichiometric ratios, or adjusting reaction conditions. These materials were stable at temperatures >300 °C and were compatible with the polymer matrices used to prepare mixed- matrix membranes (MMMs). MMMs tested at 300 °C exhibited a >30 fold increase in permeability, compared to those measured at 35 °C, while maintaining H{sub 2}/CO{sub 2} selectivity. Measurements at high pressure (up to 30 atm) and high temperature (up to 300 °C) resulted in an increase in gas flux across the membrane with retention of selectivity. No variations in permeability were observed at high pressures at either 35 or 300 °C. CO{sub 2}-induced plasticization was not observed for Matrimid®, VTEC, and PBI polymers or their MMMs at 30 atm and 300 °C. Membrane surface modification by cross-linking with ethanol diamine resulted in an increase in H{sub 2}/CO{sub 2} selectivity at 35 °C. Spectrometric analysis showed that the cross-linking was effective to temperatures <150 °C. At higher temperatures, the cross-linked membranes exhibit a H{sub 2}/CO{sub 2} selectivity similar to the uncross-linked polymer. Performance of the polybenzimidazole (PBI) hollow fibers prepared at Santa Fe Science and Technology (SFST, Inc.) showed increased flux o to a flat PBI membrane. A water-gas shift reactor has been built and currently being optimized for testing under DOE conditions.

  13. Glomerular basement membrane composition and the filtration barrier.

    PubMed

    Miner, Jeffrey H

    2011-09-01

    The glomerular basement membrane (GBM) is an especially thick basement membrane that contributes importantly to the kidney's filtration barrier. The GBM derives from the fusion of separate podocyte and endothelial cell basement membranes during glomerulogenesis and consists primarily of laminin-521 (α5β2γ1), collagen α3α4α5(IV), nidogens-1 and -2, and agrin. Of these nine proteins, mutations in the genes encoding four of them (LAMB2, COL4A3, COL4A4, and COL4A5) cause glomerular disease in humans as well as in mice. Furthermore, mutation of a fifth (Lama5) gene in podocytes in mice causes proteinuria, nephrotic syndrome, and progression to renal failure. These results highlight the importance of the GBM for establishing and maintaining a properly functioning glomerular filtration barrier.

  14. Chelating polymer modified P84 nanofiltration (NF) hollow fiber membranes for high efficient heavy metal removal.

    PubMed

    Gao, Jie; Sun, Shi-Peng; Zhu, Wen-Ping; Chung, Tai-Shung

    2014-10-15

    High performance nanofiltration (NF) membranes for heavy metal removal have been molecularly designed by adsorption of chelating polymers containing negatively charged functional groups such as poly (acrylic acid-co-maleic acid) (PAM), poly (acrylic acid) (PAA) and poly (dimethylamine-co-epichlorohydrin-co-ethylenediamine) (PDMED) on the positively charged polyethyleneimine (PEI) cross-linked P84 hollow fiber substrates. Not only do these chelating polymers change the membrane surface charge and pore size, but also provide an extra mean to remove heavy metal ions through adsorption in addition to traditional steric effect and Donnan exclusion. The adsorbed membranes have comparable water permeability and superior rejections to heavy metals, for instance, Pb(NO3)2, CuSO4, NiCl2, CdCl2, ZnCl2, Na2Cr2O7 and Na2HAsO4, with rejections higher than 98%. The membranes also display excellent rejections to mixed ions with rejections more than 99%. The newly developed membranes show reasonably stability during 60-h tests as well as multiple washes.

  15. Method for Synthesizing Metal Nanowires in Anodic Alumina Membranes Using Solid State Reduction

    NASA Technical Reports Server (NTRS)

    Martinez-Inesta, Maria M (Inventor); Feliciano, Jennie (Inventor); Quinones-Fontalvo, Leonel (Inventor)

    2016-01-01

    The invention proposes a novel method for the fabrication of regular arrays of MNWs using solid-state reduction (SSR). Using this method copper (Cu), silver (Ag), and palladium (Pd) nanowire (NWs) arrays were synthesized using anodic alumina membranes (AAMs) as templates. Depending on the metal loading used the NWs reached different diameters.

  16. Nanofiber Ion-Exchange Membranes for the Rapid Uptake and Recovery of Heavy Metals from Water.

    PubMed

    Chitpong, Nithinart; Husson, Scott M

    2016-12-20

    An evaluation of the performance of polyelectrolyte-modified nanofiber membranes was undertaken to determine their efficacy in the rapid uptake and recovery of heavy metals from impaired waters. The membranes were prepared by grafting poly(acrylic acid) (PAA) and poly(itaconic acid) (PIA) to cellulose nanofiber mats. Performance measurements quantified the dynamic ion-exchange capacity for cadmium (Cd), productivity, and recovery of Cd(II) from the membranes by regeneration. The dynamic binding capacities of Cd(II) on both types of nanofiber membrane were independent of the linear flow velocity, with a residence time of as low as 2 s. Analysis of breakthrough curves indicated that the mass flow rate increased rapidly at constant applied pressure after membranes approached equilibrium load capacity for Cd(II), apparently due to a collapse of the polymer chains on the membrane surface, leading to an increased porosity. This mechanism is supported by hydrodynamic radius (Rh) measurements for PAA and PIA obtained from dynamic light scattering, which show that Rh values decrease upon Cd(II) binding. Volumetric productivity was high for the nanofiber membranes, and reached 0.55 mg Cd/g/min. The use of ethylenediaminetetraacetic acid as regeneration reagent was effective in fully recovering Cd(II) from the membranes. Ion-exchange capacities were constant over five cycles of binding-regeneration.

  17. Nanofiber Ion-Exchange Membranes for the Rapid Uptake and Recovery of Heavy Metals from Water

    PubMed Central

    Chitpong, Nithinart; Husson, Scott M.

    2016-01-01

    An evaluation of the performance of polyelectrolyte-modified nanofiber membranes was undertaken to determine their efficacy in the rapid uptake and recovery of heavy metals from impaired waters. The membranes were prepared by grafting poly(acrylic acid) (PAA) and poly(itaconic acid) (PIA) to cellulose nanofiber mats. Performance measurements quantified the dynamic ion-exchange capacity for cadmium (Cd), productivity, and recovery of Cd(II) from the membranes by regeneration. The dynamic binding capacities of Cd(II) on both types of nanofiber membrane were independent of the linear flow velocity, with a residence time of as low as 2 s. Analysis of breakthrough curves indicated that the mass flow rate increased rapidly at constant applied pressure after membranes approached equilibrium load capacity for Cd(II), apparently due to a collapse of the polymer chains on the membrane surface, leading to an increased porosity. This mechanism is supported by hydrodynamic radius (Rh) measurements for PAA and PIA obtained from dynamic light scattering, which show that Rh values decrease upon Cd(II) binding. Volumetric productivity was high for the nanofiber membranes, and reached 0.55 mg Cd/g/min. The use of ethylenediaminetetraacetic acid as regeneration reagent was effective in fully recovering Cd(II) from the membranes. Ion-exchange capacities were constant over five cycles of binding-regeneration. PMID:27999394

  18. Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

  19. Effect of Composite Substrates on the Mechanical Behavior of Brazed Joints in Metal-Composite System

    NASA Technical Reports Server (NTRS)

    Singh, M.; Morscher, Gregory N.; Shpargel, Tarah; Asthana, Rajiv

    2006-01-01

    Advanced composite components are being considered for a wide variety of demanding applications in aerospace, space exploration, and ground based systems. A number of these applications require robust integration technologies to join dissimilar materials (metalcomposites) into complex structural components. In this study, three types of composites (C-C, C-SiC, and SiC-SiC) were vacuum brazed to commercially pure Ti using the active metal braze alloy Cusil-ABA (63Ag-35.3Cu-1.75Ti). Composite substrates with as fabricated and polished surfaces were used for brazing. The microstructure and composition of the joint, examined using scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), showed sound metallurgical bonding in all systems. The butt strap tensile (BST) test was performed on bonded specimens at room and elevated temperatures. Effect of substrate composition, interlaminar properties, and surface roughness on the mechanical properties and failure behavior of joints will be discussed.

  20. Novel Nonporous Fouling-Resistant Composite Nanofiltration Membranes and Membrane Separation Systems for Wastewater Treatment.

    DTIC Science & Technology

    2007-11-02

    nanofiltration can produce dischargeable water, but all current nanofiltration membranes are finely porous and only moderately hydrophilic. They are... nanofiltration systems by lowering capital costs, reducing energy consumption, and decreasing system down-time.

  1. Rheological properties of poly(vinyl alcohol) (PVA) derived composite membranes for fuel cells

    NASA Astrophysics Data System (ADS)

    Remiš, T.

    2017-01-01

    Rheological properties of new anhydrous proton conducting membrane based on PVA, tetraethyl orthosilicate (TEOS),sulfosuccinic acid (SSA), titanium dioxide (TiO2)was examined at various stoichiometric ratios. SSA was used as sulfonating agents to form a crosslinked structure and as proton source, whereas TEO Sand TiO2were utilized to improve the thermal and mechanical properties of the membrane. In order to verify that all the substances were immobilized into the matrix, the membranes were analysed by means of FT-IR. The rheological, mechanical and thermal properties of the membranes were investigated using rheometer ARES G2 and thermogravimetic analyser (TGA).The analysis of mixed PVA solutions exhibited a unique behaviour of viscosity with increased crosslink density. The dynamic storage modulus G´ of dried composite membranes shows better mechanical resistance and increased tolerance to pressure applied during membrane electrode assembly (MEA).

  2. Swelling and morphology of the skin layer of polyamide composite membranes: an atomic force microscopy study.

    PubMed

    Freger, Viatcheslav

    2004-06-01

    The paper introduces a new methodology for studying polyamide composite membranes for reverse osmosis (RO) and nanofiltration (NF) in liquid environments. The methodology is based on atomic force microscopy of the active layer, which had been separated from the support and placed on a solid substrate. The approach was employed to determine the thickness, interfacial morphology, and dimensional changes in solution (swelling) of polyamide films. The face (active) and back (facing the support) surfaces of the RO films appeared morphologically similar, in agreement with the recently proposed model of skin formation. Measured thickness and swelling data in conjunction with the intrinsic permeability of the membranes suggest that the selective barrier in RO membrane constitutes only a fraction of the polyamide skin, whereas NF membranes behave as nearly uniform films. For NF membranes, there was reasonable correlation between the changes in the swelling and in the permeability of the membrane and the salinity and pH of the feed.

  3. Composite hydrogen separation element and module

    DOEpatents

    Edlund, David J.; Newbold, David D.; Frost, Chester B.

    1997-01-01

    There are disclosed improvements in multicomponent composite metal membranes useful for the separation of hydrogen, the improvements comprising the provision of at least one common-axis hole through all components of the composite membrane and the provision of a gas-tight seal around the periphery of the hole or holes through a coating metal layer of the membrane.

  4. Composite hydrogen separation element and module

    DOEpatents

    Edlund, D.J.; Newbold, D.D.; Frost, C.B.

    1997-07-08

    There are disclosed improvements in multicomponent composite metal membranes useful for the separation of hydrogen, the improvements comprising the provision of at least one common-axis hole through all components of the composite membrane and the provision of a gas-tight seal around the periphery of the hole or holes through a coating metal layer of the membrane. 11 figs.

  5. A physics-based model of the electrical impedance of ionic polymer metal composites

    NASA Astrophysics Data System (ADS)

    Cha, Youngsu; Aureli, Matteo; Porfiri, Maurizio

    2012-06-01

    In this paper, we analyze the chemoelectrical behavior of ionic polymer metal composites (IPMCs) in the small voltage range with a novel hypothesis on the charge dynamics in proximity of the electrodes. In particular, we homogenize the microscopic properties of the interfacial region through a so-called composite layer which extends between the polymer membrane and the metal electrode. This layer accounts for the dissimilar properties of its constituents by describing the charge distribution via two species of charge carriers, that is, electrons and mobile counterions. We model the charge dynamics in the IPMC by adapting the multiphysics formulation based on the Poisson-Nernst-Planck (PNP) framework, which is enriched through an additional term to capture the electron transport in the composite layer. Under the hypothesis of small voltage input, we use the linearized PNP model to derive an equivalent IPMC circuit model with lumped elements. The equivalent model comprises a resistor connected in series with the parallel of a capacitor and a Warburg impedance element. These elements idealize the phenomena of charge build up in the double layer region and the faradaic impedance related to mass transfer, respectively. We validate the equivalent model through measurements on in-house fabricated samples addressing both IPMC step response and impedance, while assessing the influence of repeated plating cycles on the electrical properties of IPMCs. Experimental results are compared with theoretical findings to identify the equivalent circuit parameters. Findings from this study are compared with alternative impedance models proposed in the literature.

  6. Fabrication, characteristics and electrical model of an ionic polymer metal-carbon nanotube composite

    NASA Astrophysics Data System (ADS)

    He, Qingsong; Song, Linlin; Yu, Min; Dai, ZhenDong

    2015-07-01

    We develop an ionic polymer metal-carbon nanotube composite (IPMCC) actuator composed of a multiwalled carbon nanotube (MWCNT)/Nafion membrane sandwiched between two hybrid electrodes, composed of palladium, platinum and MWCNTs. The surface morphology and cross-sectional structure of the metal-carbon nanotube hybrid electrode were observed using scanning electron microscopy (SEM). SEM investigation indicated that the MWCNT layer can adhere very well with the platinum-palladium metal electrode, fill the cracks in the metal surface, and prevent the oxidation of nanoscale platinum particles. These observations show that the surface resistance of the total electrode is retained and the stability of electrode property is maintained. The displacement, blocking force and nonlinear current versus voltage (V-I) characteristics were measured. Compared with an ionic polymer metal composite (IPMC), the IPMCC shows a more stable displacement and blocking force under 1, 1.2 and 2 V at 0.1 Hz, and 2.34-3.29 times higher effective air-operating time under 3 V at 0.1 Hz. It can be observed from the V-I characteristics that the change in shape becomes significant at amplitudes higher than 1.2 V. An equivalent circuit is used to model the nonlinear behavior of the IPMCC, in which the leakage current was taken into account and analyzed. The values of the components in the circuit are estimated and electrical behavior is simulated by using the Pspice software. Compared with the model with no consideration of the leakage current, the simulations obtained by the model considering leakage current showed better agreement with the experimental results. The impressive leakage current (20 mA), which is successfully simulated by the proposed model with the nonlinear circuit, is shown to play an important role in the total current.

  7. Modified effective dielectric function for metallic granular composites with high percolation threshold.

    PubMed

    Su, Xiong-Rui; Zhang, Zong-Suo; Liu, Shao-Ding; Hao, Zhong-Hua

    2010-03-01

    We propose the effective dielectric function theory of metal granular composites modified with the metal particle size. The modified theory is used to explain the electrical conductivity, resonant plasmon absorption, and large nonlinear absorption of Au-TiO2 granular composite films with high-density metallic particles and a high electric percolation threshold. It is revealed that the decreasing metal particle size leads to an increasing percolation threshold and large enhancement of optical nonlinearity of the composites.

  8. Enhancement of the fuel cell performance of a high temperature proton exchange membrane fuel cell running with titanium composite polybenzimidazole-based membranes

    NASA Astrophysics Data System (ADS)

    Lobato, Justo; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Pinar, F. Javier

    2011-10-01

    The fuel cell performance of a composite PBI-based membrane with TiO2 has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The PBI composite membrane incorporating TiO2 showed the best performance and reached 1000 mW cm-2 at 175 °C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 mΩ cm2 h-1 and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H3PO4/PBI r.u. whereas the PBI standard membrane only retained 1 mol H3PO4/PBI r.u. Taking into account the results obtained in this study, the TiO2-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs.

  9. Performance of a membrane bioreactor used for the treatment of wastewater contaminated with heavy metals.

    PubMed

    Katsou, Evina; Malamis, Simos; Loizidou, Maria

    2011-03-01

    In this work the performance of a Membrane bioreactor (MBR) was assessed for the removal of 3-15 mg/l of copper, lead, nickel and zinc from wastewater. The average removal efficiencies accomplished by the MBR system were 80% for Cu(II), 98% for Pb(II), 50% for Ni(II) and 77% for Zn(II). The addition of 5 g/l vermiculite into the biological reactor enhanced metal removal to 88% for copper, 85% for zinc and 60% for nickel due to adsorption of metal ions on the mineral, while it reduced biomass inhibition and increased biomass growth. The metal ions remaining in soluble form penetrated into the permeate, while those attached to sludge flocs were effectively retained by the ultrafiltration membranes. The average heterotrophic biomass inhibition was 50%, while it reduced to 29% when lower metal concentrations were fed into the reactor in the presence of vermiculite. The respective autotrophic biomass inhibition was 70% and 36%. The presence of heavy metals and vermiculite in the mixed liquor adversely impacted on membrane fouling.

  10. Robust Thermoresponsive Polymer Composite Membrane with Switchable Superhydrophilicity and Superhydrophobicity for Efficient Oil-Water Separation.

    PubMed

    Ou, Ranwen; Wei, Jing; Jiang, Lei; Simon, George P; Wang, Huanting

    2016-01-19

    Herein, we report for the first time on the fabrication of a robust, thermoresponsive polymer membrane produced by the combination of an elastic polyurethane (TPU) microfiber web and poly(N-isopropylacrylamide) (PNIPAM). PNIPAM hydrogel is evenly coated on the surface of TPU microfibers, and thus, the wettability of TPU-PNIPAM membrane is amplified by taking advantage of the hierarchical structure and increased surface roughness. The TPU-PNIPAM membrane possesses switchable superhydrophilicity and superhydrophobicity as the temperature of membrane changes from 25 to 45 °C. The composite membrane is shown successfully able to separate a 1 wt % oil-in-water emulsion and 1 wt % water-in-oil emulsion at 25 and 45 °C, respectively, with a high separation efficiency of ≥99.26%. Furthermore, the composite membranes show excellent mechanical properties, and they are highly flexible and mechanically tough. The smart composite membranes reported here have shown great potential for further development for practical high-efficiency oil-water separations.

  11. Transport Properties of Multivalent Cations in Nafion-117 Membrane with Mixed Ionic Composition.

    PubMed

    Chaudhury, Sanhita; Agarwal, Chhavi; Goswami, A

    2015-08-20

    The transport characteristics of multivalent cations like Ba(2+) and Eu(3+) have been studied in bi-ionic form of the Nafion-117 membrane. The membranes have been prepared by loading different proportions of H(+)-Ba(2+)/Mg(2+)-Ba(2+)/Ba(2+)-Eu(3+)/H(+)-Eu(3+)/Na(+)-Eu(3+). The cationic compositions of the membranes have been determined from the measured ion exchange isotherms. Results show that the self-diffusion coefficient of Ba(2+) (D(Ba)) in H-Ba/Mg-Ba systems as well as the self-diffusion coefficient of Eu(3+) (D(Eu)) in H-Eu/Na-Eu systems are strongly dependent on the membrane ionic compositions and decreased continuously with increasing concentration of the highly hydrated ions (H(+)/Na(+)/Mg(2+)) in the membrane. Increase in the proportion of H(+)/Na(+)/Mg(2+) ions in the membrane increases the effective charge on the membrane matrix. This causes stronger electrostatic interaction of the less hydrated multivalent ions (Ba(2+)/Eu(3+)) with the membrane matrix charges, which ultimately results in their slower self-diffusion coefficients. The higher the valence, the stronger the electrostatic interaction is with the fixed ionic charges; hence, in general, D(Eu) is affected more as compared to D(Ba). On the basis of the free-volume theory for polymers, the effective interaction potential (Φ) of the Ba(2+) with the fixed ionic sites in the membrane has been calculated and found to be on the order of approximately millivolts. The higher the proportion of hydrated ion in the membrane, the higher the Φ is and the stronger the ion pair formation is with the fixed ionic sites in the membrane. However, in the Ba-Eu system, as the electrostatic interactions of the two ions with the membrane matrix are close, D(Ba) and D(Eu) are independent of the membrane ionic composition. The ionic composition dependence of D(Ba) in the H-Ba system is reflected in the transport rate of Ba(2+), showing the importance of such measurements in understanding the transport

  12. Biofouling Mitigation in Forward Osmosis Using Graphene Oxide Functionalized Thin-Film Composite Membranes.

    PubMed

    Perreault, François; Jaramillo, Humberto; Xie, Ming; Ude, Mercy; Nghiem, Long D; Elimelech, Menachem

    2016-06-07

    Forward osmosis (FO) is an emerging membrane process with potential applications in the treatment of highly fouling feedwaters. However, biofouling, the adhesion of microorganisms to the membrane and the subsequent formation of biofilms, remains a major limitation since antifouling membrane modifications offer limited protection against biofouling. In this study, we evaluated the use of graphene oxide (GO) for biofouling mitigation in FO. GO functionalization of thin-film composite membranes (GO-TFC) increased the surface hydrophilicity and imparted antimicrobial activity to the membrane without altering its transport properties. After 1 h of contact time, deposition and viability of Pseudomonas aeruginosa cells on GO-TFC were reduced by 36% and 30%, respectively, compared to pristine membranes. When GO-TFC membranes were tested for treatment of an artificial secondary wastewater supplemented with P. aeruginosa, membrane biofouling was reduced by 50% after 24 h of operation. This biofouling resistance is attributed to the reduced accumulation of microbial biomass on GO-TFC compared to pristine membranes. In addition, confocal microscopy demonstrated that cells deposited on the membrane surface are inactivated, resulting in a layer of dead cells on GO-TFC that limit biofilm formation. These findings highlight the potential of GO to be used for biofouling mitigation in FO.

  13. Preparation and characterization of N-methylene phosphonic and quaternized chitosan composite membranes for electrolyte separations.

    PubMed

    Saxena, Arunima; Kumar, Arvind; Shahi, Vinod K

    2006-11-15

    Chitosan was functionalized either by introducing a phosphonic acid group or by quaternization of existing primary ammonium groups in order to make it a water-soluble material. Functionalized chitosans and poly(vinyl alcohol) (PVA)-based nanoporous charged membranes were prepared in aqueous media and gelated in methanol at 10 degrees C to tailor their pore structure. These membranes were extensively characterized for their physicochemical, electrochemical, and permeation characteristics using FTIR, TGA, DSC, water content, ion-exchange capacity, ionic transport properties, and membrane permeability studies. N-Methylene phosphonic chitosan (NMPC)/PVA-based membranes exhibited mild cation selectivity and quaternized chitosan (QC)/PVA composite membranes had mild anion selectivity, while a blend of NMPC-QC/PVA membranes exhibited weak cation selectivity because of formation of zwitterionic structure. Viscosity measurements and interaction studies for individual and mixed solutions of NMPC and QC were carried out for the prediction of charge interactions between -PO3H2 and -N+(CH3)3 groups and effect on molecular weight due to functionalization. Elaborate electrochemical and permeation experiments were conducted in order to predict suitability of these membranes for the separation of mono- and bivalent electrolytes based on their hydrated ionic radius, and it was found that among all the synthesized membranes, PC/QC-30 had the highest relative permeability, which may extend its suitability for electrolyte separations. Observations were correlated with equivalent pore radius of the different membranes as estimated by membrane permeability measurements.

  14. Synthesis of highly conductive cotton fiber/nanostructured silver/polyaniline composite membranes for water sterilization application

    NASA Astrophysics Data System (ADS)

    Abu-Thabit, Nedal Y.; Basheer, Rafil A.

    2014-09-01

    Electrically conductive composite membranes (ECCMs) composed of cotton fibers, conductive polyaniline and silver nanostructures were prepared and utilized as electrifying filter membranes for water sterilization. Silver metal and polyaniline were formed in situ during the oxidative polymerization of aniline monomers in the presence of silver nitrate as weak oxidizing agent. The reaction was characterized by long induction period and the morphology of the obtained ECCMs contained silver nanoparticles and silver flakes of 500-1000 nm size giving a membrane electrical resistance in the range of 10-30 Ohm sq-1. However, when dimethylformamide (DMF) was employed as an auxiliary reducing agent to trigger and speed up the polymerization reaction, silver nanostructures such as wires, ribbons, plates were formed and were found to be embedded between polyaniline coating and cotton fibers. These ECCMs exhibited a slightly lower resistance in the range of 2-10 Ohm sq.-1 and, therefore, were utilized for the fabrication of a bacteria inactivation device. When water samples containing 107-108 CFU mL-1 E. coli bacteria were passed through the prepared ECCMs by gravity force, with a filtration rate of 0.8 L h-1 and at an electric potential of 20 V, the fabricated device showed 92% bacterial inactivation efficiency. When the treated solution was passed through the membrane for a second time under the same conditions, no E. coli bacteria was detected.

  15. Highly efficient metal grating coupler for membrane-based integrated photonics.

    PubMed

    Dolores-Calzadilla, V; Heiss, D; Smit, M

    2014-05-01

    We present the design of a metal grating coupler compatible with membrane photonic circuit platforms, consisting of a buried metal grating and a metal mirror. A nonapodized design provides a fiber-to-chip coupling efficiency at 1.55 μm up to 73%, whereas apodized designs show theoretical efficiencies as high as 89%, with a 3 dB bandwidth of 61 and 78 nm, respectively. An important advantage is that the coupling efficiency is independent from the underlying layer stack, enabling its use in diverse applications. For example, a thin buffer layer is required to achieve optical coupling for the heterogeneous integration of III-V and silicon photonics, whereas a thick buffer is of interest for thermal isolation between photonic membranes and CMOS circuits.

  16. Casting of Ashalloy metal matrix composites: 1994. Interim report

    SciTech Connect

    Rohatgi, P.K.

    1996-05-01

    Research carried out so far has demonstrated that aluminum-fly ash composites, ``Ashalloy,`` containing up to 20 vol% fly ash may be synthesized by stir casting techniques. Composites containing still higher volume percent fly ash, up to 60 vol%, can be produced by pressure infiltration. A variety of shapes were cast from the slurry of molten aluminum alloy containing fly ash particles and it is now possible to explore application of Ashalloy composites in various industries. The potential advantages of Ashalloy composites lie in (a) a high value added use of coal fly ash, (b) saving energy by replacing metal with fly ash, (c) improving certain properties of the base alloy at a reduced cost, and (d) solving the disposal problem of fly ash. Fabrication of Ashalloy components may require both casting and deformation processing techniques, since Ashalloy can find applications in wrought components as well as in castings. In addition, machining will be frequently required to produce final dimensions, except in net shaped processing. The presence of hard and abrasive fly ash particles may cause serious problem of abrasive wear. Research efforts carried out to demonstrate abrasive wear behavior, machinability, and forgeability of Ashalloy composites are reported here.

  17. Enhanced CO2 permeability of membranes by incorporating polyzwitterion@CNT composite particles into polyimide matrix.

    PubMed

    Liu, Ye; Peng, Dongdong; He, Guangwei; Wang, Shaofei; Li, Yifan; Wu, Hong; Jiang, Zhongyi

    2014-08-13

    In this study, polyzwitterion is introduced into a CO2 separation membrane. Composite particles of polyzwitterion coated carbon nanotubes (SBMA@CNT) are prepared via a precipitation polymerization method. Hybrid membranes are fabricated by incorporating SBMA@CNT in polyimide matrix and utilized for CO2 separation. The prepared composite particles and hybrid membranes are characterized by transmission electron microscopy (TEM) with element mapping, field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC) and an electronic tensile machine. Water uptake and water state of membranes are measured to probe the relationship among water uptake, water state and CO2 transport behavior. Hybrid membranes show significantly enhanced CO2 permeability compared to an unfilled polyimide membrane at a humidified state. A hybrid membrane with 5 wt % SBMA@CNT exhibits the maximum CO2 permeability of 103 Barrer with a CO2/CH4 selectivity of 36. The increase of CO2 permeability is attributed to the incorporation of the SBMA@CNT composite particles. First, SBMA@CNT form interconnected channels for CO2 transport due to the facilitated transport effect of the quaternary ammonium in repeat unit of pSBMA. Second, SBMA@CNT improve water uptake and adjust water state of membrane, which further increases CO2 permeability. Meanwhile, the variation of CO2/CH4 selectivity is dependent on the bound water portion in the membrane. A gas permeation test at a dry state and a pressure test are conducted to further probe the membrane separation performance.

  18. Modification of Thin Film Composite (TFC) Membrane by Incorporation with Copper Nanoparticles (Cu-NPs) for Antibacterial Properties

    NASA Astrophysics Data System (ADS)

    Zhong, Chen

    Membrane biofouling has been a challenging problem restricting the application of reverse osmosis (RO) desalination process. Copper is known for its antimicrobial properties and is easily available with low cost. In this paper, copper nanoparticles (Cu-NPs) with a mean diameter of 15nm were synthesized by the reduction of copper (II) chloride with sodium borohydride (NaBH4), using cetyl trimethylammonium bromide ((C16H33)N(CH3) 3Br, CTAB) as a capping agent. After purification of Cu-NPs by dialysis, the particles were successfully immobilized onto the surface of thin film composite (TFC) membranes via either electrostatic interactions or by covalent bonding with cysteamine as a linker. The electrostatic method was simply to immerse the newly made TFC membranes to the Cu-NPs suspension. Since the CTAB had formed cationic bilayer outside the Cu-NPs, the Cu-NPs was not only adsorbed on the membranes but also attached to the surface because of the electrostatic effect with the negatively charged membrane surface. The covalent bonding method utilized cysteamine (C4H12N2S 2) to activate the thin film layer with thiol functional groups first and then incorporated the metallic copper nanoparticles to form the stable covalent chemical bonding in between. The resulting membranes by these two methods were labeled as TFC-CuNPs and TFC-S-CuNPs, respectively, in this study. Scanning electron microscopy (SEM) imaging and associated energy-dispersive X-ray spectroscopy (EDS) showed that large amounts of Cu-NPs existed on both types of membranes. Surface hydrophilicity of the membranes was enhanced by the presence of Cu-NPs, as indicated by the measured contact angle of 63.25 +/- 0.75 for TFC, 38.63 +/- 2.16 for TFC-CuNPs, and 58.00 +/- 3.39 for TFC-S-CuNPs. Consistently, the water flux obtained from the RO desalination system was increased from 47.07 +/- 0.84 for TFC, 49.10 +/- 0.22 for TFC-CuNPs, and 69.13 +/- 1.43 for TFC-S-CuNPs, with this increase in hydrophilicity. The salt

  19. Metal-organic framework composites: from fundamentals to applications

    NASA Astrophysics Data System (ADS)

    Li, Shaozhou; Huo, Fengwei

    2015-04-01

    Metal-organic frameworks (MOFs) are a class of crystallized porous polymeric materials consisting of metal ions or clusters linked together by organic bridging ligands. Due to their permanent porosity, rich surface chemistry and tuneable pore sizes, MOFs have emerged as one type of important porous solid and have attracted intensive interests in catalysis, gas adsorption, separation and storage over the past two decades. When compared with pure MOFs, the combination of MOFs with functional species or matrix materials not only shows enhanced properties, but also broadens the applications of MOFs in new fields, such as bio-imaging, drug delivery and electrical catalysis, owing to the interactions of the functional species/matrix with the MOF structures. Although the synthesis, chemical modification and potential applications of MOFs have been reviewed previously, there is an increasing awareness on the synthesis and applications of their composites, which have rarely been reviewed. This review aims to fill this gap and discuss the fabrication, properties, and applications of MOF composites. The remaining challenges and future opportunities in this field, in terms of processing techniques, maximizing composite properties, and prospects for applications, have also been indicated.

  20. Effects of weight loss on erythrocyte membrane composition and fluidity in overweight and moderately obese women.

    PubMed

    Cazzola, Roberta; Rondanelli, Mariangela; Trotti, Rosita; Cestaro, Benvenuto

    2011-04-01

    A previous study showed chemical and physical impairment of the erythrocyte membrane of overweight and moderately obese women. The present study investigated the effects of a low-calorie diet (800 kcal/day deficit for 8 weeks) on erythrocyte membrane properties in 70 overweight and moderately obese (body mass index, 25-33 kg/m(2)) normotensive, nondiabetic women. At the end of dietary intervention, 24.3% of women dropped out, 45.7% lost less than 5% of their initial weight (Group I) and only 30% of patients lost at least 5% of their initial body weight (Group II). Group I showed no significant changes in erythrocyte membrane composition and function. The erythrocyte membranes of Group II showed significant reductions in malondialdehyde, lipofuscin, cholesterol, sphingomyelin, palmitic acid and nervonic acid and an increase in di-homo-γ-linolenic acid, arachidonic acid and membrane fluidity. Moreover, Group II showed an improvement in total cholesterol, low-density lipoprotein cholesterol, glycemia and insulin resistance. These changes in erythrocyte membrane composition could reflect a virtuous cycle resulting from the reduction in insulin resistance associated with increased membrane fluidity that, in turn, results in a sequence of metabolic events that concur to further improve membrane fluidity.

  1. Effect of gas composition on Ru dissolution and crossover in polymer-electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Cheng, Tommy T. H.; Jia, Nengyou; Colbow, Vesna; Wessel, Silvia; Dutta, Monica

    Pt-Ru-based anodes are commonly used in polymer-electrolyte membrane fuel cells (PEMFCs) to provide improved CO tolerance for reformate fuel applications. However, Ru crossover from the anode to the cathode has been identified as a critical durability problem that has severe performance implications. In the present study, an anode accelerated stress test (AST) was used to simulate potential spikes that occur during fuel cell start-ups and shutdowns to induce Ru crossover. The effects of fuel gas composition, namely hydrogen and carbon dioxide concentrations, on Ru dissolution and crossover were investigated. The cell performance losses were correlated with the degree of Ru crossover as determined by the changes in cathode cyclic voltammetry (CV) characteristics and neutron activation analysis (NAA). It was found that higher hydrogen concentration in the fuel accelerated Ru crossover and that the presence of carbon dioxide hindered Ru crossover. In particular, the injection of 20 vol.% carbon dioxide during potential cycling resulted in very minor Ru crossover, which showed essentially identical performance losses and CV characteristic changes as a fuel cell composed of a Ru-free anode. The experimental results suggest that the Ru species in our Pt-Ru metal oxide catalysts need to go through a reduction step by hydrogen before dissolution. The presence of carbon dioxide may play a role in hindering the reduction step.

  2. Ultrafine-grained Aluminm and Boron Carbide Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Vogt, Rustin

    Cryomilling is a processing technique used to generate homogenously distributed boron carbide (B4C) particulate reinforcement within an ultrafine-grained aluminum matrix. The motivation behind characterizing a composite consisting of cryomilled aluminum B4C metal matrix composite is to design and develop a high-strength, lightweight aluminum composite for structural and high strain rate applications. Cryomilled Al 5083 and B4C powders were synthesized into bulk composite by various thermomechanical processing methods to form plate and extruded geometries. The effects of processing method on microstructure and mechanical behavior for the final consolidated composite were investigated. Cryomilling for extended periods of time in liquid nitrogen has shown to increase strength and thermal stability. The effects associated with cryomilling with stearic acid additions (as a process-control agent) on the degassing behavior of Al powders is investigated and results show that the liberation of compounds associated with stearic acid were suppressed in cryomilled Al powders. The effect of thermal expansion mismatch strain on strengthening due to geometrically necessary dislocations resulting from quenching is investigated and found not to occur in bulk cryomilled Al 5083 and B 4C composites. Previous cryomilled Al 5083 and B4C composites have exhibited ultrahigh strength associated with considerable strain-to-failure (>14 pct.) at high strain rates (>103/s) during mechanical testing, but only limited strain-to-failure (˜0.75 pct.) at quasi-static strain rates (10-3/s). The increased strain to failure at high strain rates is attributed to micro-flaw developments, including kinking, extensive axial splitting, and grain growth were observed after high strain rate deformation, and the significance of these mechanisms is considered.

  3. Metal-nanotube composites as radiation resistant materials

    NASA Astrophysics Data System (ADS)

    González, Rafael I.; Valencia, Felipe; Mella, José; van Duin, Adri C. T.; So, Kang Pyo; Li, Ju; Kiwi, Miguel; Bringa, Eduardo M.

    2016-07-01

    The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

  4. Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

    2001-01-01

    We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

  5. Metal Alloy Compositions And Process Background Of The Invention

    DOEpatents

    Flemings, Merton C.; Martinez-Ayers, Raul A.; de Figueredo, Anacleto M.; Yurko, James A.

    2003-11-11

    A skinless metal alloy composition free of entrapped gas and comprising primary solid discrete degenerate dendrites homogeneously dispersed within a secondary phase is formed by a process wherein the metal alloy is heated in a vessel to render it a liquid. The liquid is then rapidly cooled while vigorously agitating it under conditions to avoid entrapment of gas while forming solid nuclei homogeneously distributed in the liquid. Agitation then is ceased when the liquid contains a small fraction solid or the liquid-solid alloy is removed from the source of agitation while cooling is continued to form the primary solid discrete degenerate dendrites in liquid secondary phase. The solid-liquid mixture then can be formed such as by casting.

  6. Membrane transporters and protein traffic networks differentially affecting metal tolerance: a genomic phenotyping study in yeast

    PubMed Central

    Ruotolo, Roberta; Marchini, Gessica; Ottonello, Simone

    2008-01-01

    Background The cellular mechanisms that underlie metal toxicity and detoxification are rather variegated and incompletely understood. Genomic phenotyping was used to assess the roles played by all nonessential Saccharomyces cerevisiae proteins in modulating cell viability after exposure to cadmium, nickel, and other metals. Results A number of novel genes and pathways that affect multimetal as well as metal-specific tolerance were discovered. Although the vacuole emerged as a major hot spot for metal detoxification, we also identified a number of pathways that play a more general, less direct role in promoting cell survival under stress conditions (for example, mRNA decay, nucleocytoplasmic transport, and iron acquisition) as well as proteins that are more proximally related to metal damage prevention or repair. Most prominent among the latter are various nutrient transporters previously not associated with metal toxicity. A strikingly differential effect was observed for a large set of deletions, the majority of which centered on the ESCRT (endosomal sorting complexes required for transport) and retromer complexes, which - by affecting transporter downregulation and intracellular protein traffic - cause cadmium sensitivity but nickel resistance. Conclusion The data show that a previously underestimated variety of pathways are involved in cadmium and nickel tolerance in eukaryotic cells. As revealed by comparison with five additional metals, there is a good correlation between the chemical properties and the cellular toxicity signatures of various metals. However, many conserved pathways centered on membrane transporters and protein traffic affect cell viability with a surprisingly high degree of metal specificity. PMID:18394190

  7. Cellular membrane composition requirement by antimicrobial and anticancer peptide GA-K4.

    PubMed

    Mishig-Ochir, Tsogbadrakh; Gombosuren, Davaadulam; Jigjid, Altanchimeg; Tuguldur, Badamkhatan; Chuluunbaatar, Galbadrakh; Urnukhsaikhan, Enerelt; Pathak, Chinar; Lee, Bong-Jin

    2016-12-16

    Naturally occurring antimicrobial peptides important for innate immunity are widely studied for their antimicrobial and anticancer activity. The primary target of these AMPs is believed to be the bacterial cytoplasmic membrane. However, the interaction between cytoplasmic membrane and the antimicrobial peptides remains poorly understood. Therefore to focus on the target membrane composition that is required by AMPs to interact with membranes, we have examined the interaction of the antimicrobial and anticancer active 11-residue GA-K4 (FLKWLFKWAKK) peptide with model and intact cell membranes. Effect on the structural conformational properties of GA-K4 peptide was investigated by means of far-UV CD and fluorescence spectroscopic methods. The different conformation of GA-K4 peptide in large unilamellar vesicles (LUV) bilayer and micelle environment suggest that the curvature has an influence on the secondary structure acquired by the peptide. Furthermore, the leakage experiment result confirmed that GA-K4 induced the leakage of cytoplasmic membrane in Staphylococcus аureus bacterial cells. Fluorescence data revealed the interfacial location of GA-K4 peptide in the model membranes. The blue-shift in emission wavelength by tryptophan residues in fluorescence data indicated the penetration of GA-K4 peptide in micelles and phospholipid bilayers. These results showed that the GA-K4 peptide is a membrane-active peptide and its activity depends on membrane curvature and lipid composition. Although further studies are required to confirm the mechanism of action, the data suggest mechanism of toroidal pore formation for the interaction of GA-K4 peptide with membranes. Our studies will be helpful in better understanding of the membrane requirment of peptides to express their therapeutic effects.

  8. Performance of composite Nafion/PVA membranes for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Mollá, Sergio; Compañ, Vicente

    2011-03-01

    This work has been focused on the characterization of the methanol permeability and fuel cell performance of composite Nafion/PVA membranes in function of their thickness, which ranged from 19 to 97 μm. The composite membranes were made up of Nafion® polymer deposited between polyvinyl alcohol (PVA) nanofibers. The resistance to methanol permeation of the Nafion/PVA membranes shows a linear variation with the thickness. The separation between apparent and true permeability permits to give an estimated value of 4.0 × 10-7 cm2 s-1 for the intrinsic or true permeability of the bulk phase at the composite membranes. The incorporation of PVA nanofibers causes a remarkable reduction of one order of magnitude in the methanol permeability as compared with pristine Nafion® membranes. The DMFC performances of membrane-electrode assemblies prepared from Nafion/PVA and pristine Nafion® membranes were tested at 45, 70 and 95 °C under various methanol concentrations, i.e., 1, 2 and 3 M. The nanocomposite membranes with thicknesses of 19 μm and 47 μm reached power densities of 211 mW cm-2 and 184 mW cm-2 at 95 °C and 2 M methanol concentration. These results are comparable to those found for Nafion® membranes with similar thickness at the same conditions, which were 210 mW cm-2 and 204 mW cm-2 respectively. Due to the lower amount of Nafion® polymer present within the composite membranes, it is suggested a high degree of utilization of Nafion® as proton conductive material within the Nafion/PVA membranes, and therefore, significant savings in the consumed amount of Nafion® are potentially able to be achieved. In addition, the reinforcement effect caused by the PVA nanofibers offers the possibility of preparing membranes with very low thickness and good mechanical properties, while on the other hand, pristine Nafion® membranes are unpractical below a thickness of 50 μm.

  9. Brazing SiC/SiC Composites to Metals

    NASA Technical Reports Server (NTRS)

    Steffier, Wayne S.

    2004-01-01

    Experiments have shown that active brazing alloys (ABAs) can be used to join SiC/SiC composite materials to metals, with bond strengths sufficient for some structural applications. The SiC/SiC composite coupons used in the experiments were made from polymerbased SiC fiber preforms that were chemical-vapor-infiltrated with SiC to form SiC matrices. Some of the metal coupons used in the experiments were made from 304 stainless steel; others were made from oxygen-free, high-conductivity copper. Three ABAs were chosen for the experiments: two were chosen randomly from among a number of ABAs that were on hand at the time; the third ABA was chosen because its titanium content (1.25 percent) is less than those of the other two ABAs (1.75 and 4.5 percent, respectively) and it was desired to evaluate the effect of reducing the titanium content, as described below. The characteristics of ABAs that are considered to be beneficial for the purpose of joining SiC/SiC to metal include wettability, reactivity, and adhesion to SiC-based ceramics. Prior to further development, it was verified that the three chosen ABAs have these characteristics. For each ABA, suitable vacuum brazing process conditions were established empirically by producing a series of (SiC/SiC)/ABA wetting samples. These samples were then sectioned and subjected to scanning electron microscopy (SEM) and energy-dispersive x-ray spectrometry (EDS) for analysis of their microstructures and compositions. Specimens for destructive mechanical tests were fabricated by brazing of lap joints between SiC/SiC coupons 1/8-in. (.3.2- mm) thick and, variously, stainless steel or copper tabs. The results of destructive mechanical tests and the SEM/EDS analysis were used to guide the development of a viable method of brazing the affected materials.

  10. The Role of Partial Crystallinity on Hydrogen Permeation in Fe–Ni–B–Mo Based Metallic Glass Membranes

    SciTech Connect

    Brinkman, K.; Su, D.; Fox, E.; Korinko, P.; Missimer, D.; Adams, T.

    2011-08-15

    A potentially exciting material for membrane separations are metallic glass materials due to their low cost, high elastic toughness and resistance to hydrogen embrittlement as compared to crystalline Pd-based membrane systems. However, at elevated temperatures and extended operation times structural changes including partial crystallinity may appear in these amorphous metallic systems. This study reports on the investigation of time and temperature dependent crystalline phase formation in conjunction with in situ crystallization/hydrogen permeation experiments at elevated temperatures. At temperatures near 400 C a FeNi crystalline phase appears as 22 vol.% inside the host amorphous matrix and the resulting composite structure remains stable over 3 h at temperature. The hydrogen permeation at 400 C of the partially crystalline material is similar to the fully amorphous material near 5 x 10{sup -9} mol H{sub 2}/m s Pa{sup 1/2}, while ambient temperature electrochemical permeation at 25 C revealed an order of magnitude decrease in the permeation of partially crystalline materials due to differences in the amorphous versus crystalline phase activation energy for hydrogen permeation.

  11. Thermal expansion in metal/lithia-alumina-silica (LAS) composites

    NASA Astrophysics Data System (ADS)

    Wolff, E. G.

    1988-03-01

    Lithia-alumina-silica (LAS) with metallic dispersions offers a new approach toward near-zero, isotropic, thermal expansion composites. The metallic phase contributes a positive coefficient of thermal expansion (CTE) to the negative CTE of the glass/ceramic matrix. In addition, the metal will increase the electrical and thermal conductivities over those of the matrix alone. The LAS system offers tailorable negative CTEs and light weight compared to other negative CTE ceramics. The most negative CTE phase is crystalline β-eucryptite, whose proportion in an initially glassy matrix can be controlled by heat treatment. Dispersed metal powders were both hot-pressed and cold-pressed and sintered together with LAS matrices prepared by sol gel methods. Super Invar powder was studied for its minimal CTE mismatch, while titanium powders offered a compromise between light weight and low CTE. An ultralow-expansion (ULE) glass- and linear variable differential transducer (LVDT)-based differential dilatometer was developed for rapid screening of compositions, while a double-laser Michelson interferometer was used for precise near-zero CTE measurements. The reinforced β-eucryptite glass/ceramic matrix exhibited both a U-shaped ΔL/L curve with temperature and some thermal hysteresis, depending on the fabrication and heat treatment sequences. The temperature of the zero-CTE portion of this curve was found to change with increasing titanium powder content. Results are also given for mixtures of Super Invar powders in ULE glass and β-eucryptite matrices. Negative CTEs in a LAS matrix above ambient temperatures were more difficult to obtain than below, although the use of petalite (high-silica LAS) appears promising.

  12. Conductivity in zeolite-polymer composite membranes for PEMFCs

    NASA Astrophysics Data System (ADS)

    Sancho, T.; Soler, J.; Pina, M. P.

    Structured materials, such as zeolites can be candidates to be used as electrolytes in proton exchange membrane fuel cells (PEMFC) to substitute polymeric membranes, taking advantage of their higher chemical and thermal stability and their specific adsorption properties. The possibility to work at temperatures of nearly 150 °C would make easy the selection of the fuel, decreasing the influence of CO in the catalyst poisoning, and it would also improve the kinetics of the electrochemical reactions involved. In this work, four zeolites and related materials have been studied: mordenite, NaA zeolite, umbite and ETS-10. In special, the influence of relative humidity and temperature have been carefully explored. A conductivity cell was designed and built to measure in cross direction, by using the electrochemical impedance spectroscopy. The experimental system was validated using Nafion ® as a reference material by comparing the results with bibliography data. Samples were prepared by pressing the zeolite powders, with size of 1 μm on average, using polymer PVDF (10 wt.%) as a binder. The results here obtained, in spite of not reaching the absolute values of the Nafion ® ones, show a lower effect of the dehydration phenomenon on the conduction performance in the temperature range studied (from room temperature to 150 °C). This increase of the operation temperature range would give important advantages to the PEMFC. ETS-10 sample shows the best behaviour with respect to conductivity exhibiting an activation energy value comparable with reported for Nafion ® membrane.

  13. Ethanol fermentation integrated with PDMS composite membrane: An effective process.

    PubMed

    Fu, Chaohui; Cai, Di; Hu, Song; Miao, Qi; Wang, Yong; Qin, Peiyong; Wang, Zheng; Tan, Tianwei

    2016-01-01

    The polydimethylsiloxane (PDMS) membrane, prepared in water phase, was investigated in separation ethanol from model ethanol/water mixture and fermentation-pervaporation integrated process. Results showed that the PDMS membrane could effectively separate ethanol from model solution. When integrated with batch ethanol fermentation, the ethanol productivity was enhanced compared with conventional process. Fed-batch and continuous ethanol fermentation with pervaporation were also performed and studied. 396.2-663.7g/m(2)h and 332.4-548.1g/m(2)h of total flux with separation factor of 8.6-11.7 and 8-11.6, were generated in the fed-batch and continuous fermentation with pervaporation scenario, respectively. At the same time, high titre ethanol production of ∼417.2g/L and ∼446.3g/L were also achieved on the permeate side of membrane in the two scenarios, respectively. The integrated process was environmental friendly and energy saving, and has a promising perspective in long-terms operation.

  14. Novel polyvinyl alcohol-bioglass 45S5 based composite nanofibrous membranes as bone scaffolds.

    PubMed

    Shankhwar, Nisha; Kumar, Manishekhar; Mandal, Biman B; Srinivasan, A

    2016-12-01

    Composite nanofibrous membranes based on sol-gel derived 45SiO2 24.5CaO 24.5 Na2O 6 P2O5 (bioglass, BG) and 43SiO2 24.5CaO 24.5 Na2O 6 P2O5 2Fe2O3 (magnetic bioglass, MBG) blended with polyvinyl alcohol (PVA) have been electrospun. These low cost membranes were mostly amorphous in structure with minor crystalline (sodium calcium phosphate) precipitates. All membranes were biodegradable. Among these, the composites exhibited higher tensile strength, better proliferation of human osteosarcoma MG63 cells and higher alkaline phosphatase enzyme activity than the bare PVA membrane, indicating their potential in bone tissue engineering. The magnetic PVA-MBG scaffold was also found to be a promising candidate for magnetic hyperthermia application.

  15. In vitro and in vivo evaluation of chitosan/β-glycerol phosphate composite membrane for guided bone regeneration.

    PubMed

    Cui, Jun; Liang, Jie; Wen, Yong; Sun, Xiaoning; Li, Tiejun; Zhang, Gairong; Sun, Kangning; Xu, Xin

    2014-09-01

    Chitosan and β-glycerol phosphate (CS/β-GP) composite, with a thermosensitive sol-gel transition behavior, has been tested as one of the viable materials for barrier membrane fabrication. These studies have provided us with a new concept for a guided bone regeneration (GBR) membrane design. The composition, porous structure of the membrane, and the neutral mild preparation procedures make the CS/β-GP membrane a potentially active guide for bone regeneration. In this study, the CS/β-GP composite membrane, with different concentrations of β-GP, was studied to assess their potential utility in GBR application. The initial attachment of the ST2 stromal cell line to the CS/β-GP composite membrane was better than their attachment to the pure CS membrane. The proliferation and osteoblastic differentiation of the cells were much higher on the CS/β-GP composite membrane as compared to the pure CS membrane (p < 0.05). A mild inflammatory response was observed around the implanted CS/β-GP composite membrane without any foreign body reaction that continued up to 4 weeks of postsurgery. This primary study indicated that the in vitro and in vivo bioactivities of the CS/β-GP composite membrane fulfilled the requirements for GBR technique.

  16. Hydrogen Selective Thin Palladium-Copper Composite Membranes on Alumina Supports

    SciTech Connect

    Lim, Hankwon; Oyama, S. Ted

    2011-08-15

    Thin and defect-free Pd–Cu composite membranes with high hydrogen permeances and selectivities were prepared by electroless plating of palladium and copper on porous alumina supports with pore sizes of 5 and 100 nm coated with intermediate layers. The intermediate layers on the 100 nm supports were prepared by the deposition of boehmite sols of different particle sizes, and provided a graded, uniform substrate for the formation of defect-free, ultra-thin palladium composite layers. The dependence of hydrogen flux on pressure difference was studied to understand the dominant mechanism of hydrogen transport through a Pd–Cu composite membrane plated on an alumina support with a pore size of 5 nm. The order in hydrogen pressure was 0.98, and indicated that bulk diffusion through the Pd–Cu layer was fast and the overall process was limited by external mass-transfer or a surface process. Scanning electron microscopy (SEM) images of the Pd–Cu composite membrane showed a uniform substrate created after depositing one intermediate layer on top of the alumina support and a dense Pd–Cu composite layer with no visible defects. Cross-sectional views of the membrane showed that the Pd–Cu composite layer had a top layer thickness of 160 nm (0.16 μm), which is much thinner than previously reported.

  17. Emissivity measurements in thin metallized membrane reflectors used for microwave radiometer sensors

    NASA Technical Reports Server (NTRS)

    Schroeder, Lyle C.; Cravey, Robin L.; Scherner, Michael J.; Hearn, Chase P.; Blume, Hans-Juergen C.

    1995-01-01

    This paper is concerned with electromagnetic losses in metallized films used for inflatable reflectors. An inflatable membrane is made of tough elastic material such as Kapton, and it is not electromagnetically reflective by design. A film of conducting metal is added to the membrane to enhance its reflective properties. Since the impetus for use of inflatables for spacecraft is the light weight and compact packaging, it is important that the metal film be as thin as possible. However, if the material is not conductive or thick enough, the radiation due to the emissivity of the reflector could be a significant part of the radiation gathered by the radiometer. The emissivity would be of little consequence to a radar or solar collector; but for a radiometer whose signal is composed of thermal radiation, this contribution could be severe. Bulk properties of the metal film cannot be used to predict its loss. For this reason, a program of analysis and measurement was undertaken to determine the emissivities of a number of candidate metallized film reflectors. This paper describes the three types of measurements which were performed on the metallized thin films: (1) a network analyzer system with an L-band waveguide; (2) an S-band radiometer; and (3) a network analyzer system with a C-band antenna free-space transmission system.

  18. Pressurized Shell Molds For Metal-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday K.; Lusignea, Richard N.; Cornie, James

    1993-01-01

    Balanced-pressure molds used to make parts in complex shapes from fiber-reinforced metal-matrix composite materials. In single step, molding process makes parts in nearly final shapes; only minor finishing needed. Because molding pressure same on inside and outside, mold does not have to be especially strong and can be made of cheap, nonstructural material like glass or graphite. Fibers do not have to be cut to conform to molds. Method produces parts with high content of continuous fibers. Parts stiff but light in weight, and coefficients of thermal expansion adjusted. Parts resistant to mechanical and thermal fatigue superior to similar parts made by prior fabrication methods.

  19. Simulation of Fatigue Behavior of High Temperature Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Tong, Mike T.; Singhal, Suren N.; Chamis, Christos C.; Murthy, Pappu L. N.

    1996-01-01

    A generalized relatively new approach is described for the computational simulation of fatigue behavior of high temperature metal matrix composites (HT-MMCs). This theory is embedded in a specialty-purpose computer code. The effectiveness of the computer code to predict the fatigue behavior of HT-MMCs is demonstrated by applying it to a silicon-fiber/titanium-matrix HT-MMC. Comparative results are shown for mechanical fatigue, thermal fatigue, thermomechanical (in-phase and out-of-phase) fatigue, as well as the effects of oxidizing environments on fatigue life. These results show that the new approach reproduces available experimental data remarkably well.

  20. Plastic stability of metallic glass composites under tension

    NASA Astrophysics Data System (ADS)

    Wu, F. F.; Li, S. T.; Zhang, G. A.; Wu, X. F.; Lin, P.

    2013-10-01

    The plastic stability of metallic glass composites (MGCs) under tension was investigated. There exists a critical normalized strain-hardening rate determining the plastic stability of MGCs: if the normalized strain-hardening rate is smaller than the critical normalized strain-hardening rate, the plastic instability occurs, thus, leading to localized plastic strain in MGCs; otherwise the plastic stability is in charge of the plastic deformation of the MGCs, so the strain localization or necking is effectively suppressed, which results in homogeneous elongation in MGCs.