WorldWideScience

Sample records for dense phase membrane

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

    KAUST Repository

    Villalobos Vazquez de la Parra, Luis Francisco

    2015-04-21

    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.

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

    Science.gov (United States)

    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.

  3. SUPPORTED DENSE CERAMIC MEMBRANES FOR OXYGEN SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Timothy L. Ward

    2000-06-30

    Mixed-conducting membranes have the ability to conduct oxygen with perfect selectivity at elevated temperatures, which makes them an extremely attractive alternative for oxygen separation and membrane reactor applications. The ability to reliably fabricate these membranes in thin or thick films would enable solid-state divisional limitations to be minimized, thus providing higher oxygen flux. Based on that motivation, the overall objective for this project is to develop and demonstrate a strategy for the fabrication of supported Wick film ceramic mixed conducting membranes, and improve the understanding of the fundamental issues associated with reliable fabrication of these membranes. The project has focused on the mixed-conducting ceramic composition SrCo{sub 0.5}FeO{sub x} because of its superior permeability and stability in reducing atmospheres. The fabrication strategy employed involves the deposition of SrCo{sub 0.5}FeO{sub x} thick films onto porous supports of the same composition. In the second year of this project, we completed characterization of the sintering and phase behavior of the porous SrCo{sub 0.5}FeO{sub x} supports, leading to a standard support fabrication methodology. Using a doctor blade method, pastes made from aerosol-derived SrCo{sub 0.5}FeO{sub x} powder dispersed with polyethylene glycol were applied to the supports, and the sintering behavior of the thick film membranes was examined in air and nitrogen atmospheres. It has been demonstrated that the desired crystalline phase content can be produced in the membranes, and that the material in the membrane layer can be highly densified without densifying the underlying support. However, considerable cracking and opening of the film occurred when films densified to a high extent. The addition of MgO into the SrCo{sub 0.5}FeO{sub x} supports was shown to inhibit support sintering so that temperatures up to 1300 C, where significant liquid formation occurs, could be used for film sintering

  4. Easy Fabrication of Dense Ceramic Membrane for Oxygen Separation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A combined EDTA-citrate complexing method was developed for the easy preparation of mixed oxygen-ionic and electronic conducting dense ceramic membrane for oxygen separation.The new method takes the advantage of lower calcination temperature for phase formation, lower membrane sintering temperature and higher relative density over the standard ceramic method.

  5. Dense ceramic membranes for methane conversion

    NARCIS (Netherlands)

    Bouwmeester, Henny J.M.

    2003-01-01

    Dense ceramic membranes made from mixed oxygen-ionic and electronic conducting perovskite-related oxides allow separation of oxygen from an air supply at elevated temperatures (>700 °C). By combining air separation and catalytic partial oxidation of methane to syngas into a ceramic membrane reactor,

  6. SUPPORTED DENSE CERAMIC MEMBRANES FOR OXYGEN SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Timothy L. Ward

    2002-07-01

    Mixed-conducting ceramics have the ability to conduct oxygen with perfect selectivity at elevated temperatures, making them extremely attractive as membrane materials for oxygen separation and membrane reactor applications. While the conductivity of these materials can be quite high at elevated temperatures (typically 800-1000 C), much higher oxygen fluxes, or, alternatively, equivalent fluxes at lower temperatures, could be provided by supported thin or thick film membrane layers. Based on that motivation, the objective of this project was to explore the use of ultrafine aerosol-derived powder of a mixed-conducting ceramic material for fabrication of supported thick-film dense membranes. The project focused on the mixed-conducting ceramic composition SrCo{sub 0.5}FeO{sub x} (SCFO) because of the desirable permeability and stability of that material, as reported in the literature. Appropriate conditions to produce the submicron SrCo{sub 0.5}FeO{sub x} powder using aerosol pyrolysis were determined. Porous supports of the same composition were produced by partial sintering of a commercially obtained powder that possessed significantly larger particle size than the aerosol-derived powder. The effects of sintering conditions (temperature, atmosphere) on the porosity and microstructure of the porous discs were studied, and a standard support fabrication procedure was adopted. Subsequently, a variety of paste and slurry formulations were explored utilizing the aerosol-derived SCFO powder. These formulations were applied to the porous SCFO support by a doctor blade or spin coating procedure. Sintering of the supported membrane layer was then conducted, and additional layers were deposited and sintered in some cases. The primary characterization methods were X-ray diffraction and scanning electron microscopy, and room-temperature nitrogen permeation was used to assess defect status of the membranes.We found that non-aqueous paste/slurry formulations incorporating

  7. Dense, layered membranes for hydrogen separation

    Science.gov (United States)

    Roark, Shane E.; MacKay, Richard; Mundschau, Michael V.

    2006-02-21

    This invention provides hydrogen-permeable membranes for separation of hydrogen from hydrogen-containing gases. The membranes are multi-layer having a central hydrogen-permeable layer with one or more catalyst layers, barrier layers, and/or protective layers. The invention also relates to membrane reactors employing the hydrogen-permeable membranes of the invention and to methods for separation of hydrogen from a hydrogen-containing gas using the membranes and reactors. The reactors of this invention can be combined with additional reactor systems for direct use of the separated hydrogen.

  8. Relaxation phenomena in dense gas separation membranes

    NARCIS (Netherlands)

    Wessling, Matthias

    1993-01-01

    Solution-diffusion membranes are widely used for the separation of gaseous and liquid mixtures. The separation of air (O2/N2), landfill gas (CH4/CO2) and purge gas streams (NH3/H2) in the ammonia synthesis are examples for state-of-the-art membrane gas separation processes. For the separation of liq

  9. Relaxation phenomena in dense gas separation membranes

    NARCIS (Netherlands)

    Wessling, Matthias

    1993-01-01

    Solution-diffusion membranes are widely used for the separation of gaseous and liquid mixtures. The separation of air (O2/N2), landfill gas (CH4/CO2) and purge gas streams (NH3/H2) in the ammonia synthesis are examples for state-of-the-art membrane gas separation processes. For the separation of

  10. Dense ceramic catalytic membranes and membrane reactors for energy and environmental applications.

    Science.gov (United States)

    Dong, Xueliang; Jin, Wanqin; Xu, Nanping; Li, Kang

    2011-10-21

    Catalytic membrane reactors which carry out separation and reaction in a single unit are expected to be a promising approach to achieve green and sustainable chemistry with less energy consumption and lower pollution. This article presents a review of the recent progress of dense ceramic catalytic membranes and membrane reactors, and their potential applications in energy and environmental areas. A basic knowledge of catalytic membranes and membrane reactors is first introduced briefly, followed by a short discussion on the membrane materials including their structures, composition and strategies for material development. The configuration of catalytic membranes, the design of membrane reaction processes and the high temperature sealing are also discussed. The performance of catalytic membrane reactors for energy and environmental applications are summarized and typical catalytic membrane reaction processes are presented and discussed. Finally, current challenges and difficulties related to the industrialization of dense ceramic membrane reactors are addressed and possible future research is also outlined.

  11. Myoglobin entrapment in poly(vinyl alcohol dense membranes

    Directory of Open Access Journals (Sweden)

    K. C. S. Figueiredo

    2014-09-01

    Full Text Available Our goal in this study was the immobilization of myoglobin in poly(vinyl alcohol dense membranes. Glutaraldehyde was investigated both as the crosslinking agent, aiming to increase the membrane stability in aqueous medium, and as the vehicle to bind myoglobin and PVA. Reaction and membrane synthesis were carried simultaneously in mild operating conditions in order to maintain the native protein folding. Membrane characterization comprised the water swelling degree, DSC, TGA, UV-visible spectroscopy, FTIR analysis and oxygen transport in a dialysis cell. The incorporation of myoglobin in the film decreased the water swelling degree and improved the membrane thermal properties compared to unmodified PVA membrane. The reduction of ferric iron in the prosthetic group of the protein to the ferrous form was observed. The increased affinity between oxygen and the immobilized myoglobin did not favor the release of this solute from the biocarrier.

  12. Phase Structure and Transport Properties of Dense Quark Matter

    CERN Document Server

    Schaefer, Thomas

    2010-01-01

    We provide a summary of our current knowledge of the phase structure of very dense quark matter. We concentrate on the question how the ground state at asymptotically high density -- color-flavor-locked (CFL) matter -- is modified as the density is lowered. We discuss the nature of the quasi-particle excitations, and present work on the transport properties of dense QCD matter.

  13. Phase transitions in dense 2-colour QCD

    CERN Document Server

    Boz, Tamer; Fister, Leonard; Skullerud, Jon-Ivar

    2013-01-01

    We investigate 2-colour QCD with 2 flavours of Wilson fermion at nonzero temperature T and quark chemical potential mu, with a pion mass of 700 MeV (m_pi/m_rho=0.8). From temperature scans at fixed mu we find that the critical temperature for the superfluid to normal transition depends only very weakly on mu above the onset chemical potential, while the deconfinement crossover temperature is clearly decreasing with mu. We also present results for the Landau-gauge gluon propagator in the hot and dense medium.

  14. Local Crystalline Structure in an Amorphous Protein Dense Phase.

    Science.gov (United States)

    Greene, Daniel G; Modla, Shannon; Wagner, Norman J; Sandler, Stanley I; Lenhoff, Abraham M

    2015-10-20

    Proteins exhibit a variety of dense phases ranging from gels, aggregates, and precipitates to crystalline phases and dense liquids. Although the structure of the crystalline phase is known in atomistic detail, little attention has been paid to noncrystalline protein dense phases, and in many cases the structures of these phases are assumed to be fully amorphous. In this work, we used small-angle neutron scattering, electron microscopy, and electron tomography to measure the structure of ovalbumin precipitate particles salted out with ammonium sulfate. We found that the ovalbumin phase-separates into core-shell particles with a core radius of ∼2 μm and shell thickness of ∼0.5 μm. Within this shell region, nanostructures comprised of crystallites of ovalbumin self-assemble into a well-defined bicontinuous network with branches ∼12 nm thick. These results demonstrate that the protein gel is comprised in part of nanocrystalline protein.

  15. Dense Persistent Pupillary Membrane in an Adult Patient

    Directory of Open Access Journals (Sweden)

    Yesim Altay

    2014-06-01

    Full Text Available Persistent pupillary membranes (PPM are congenital abnormalities which results from an incomplete involution of tunica vasculosa lentis and are rarely seen in adults. A thirty-year old man applied to the hospital with the complaint of uncommon-looking pupils and progressive blurring of vision in the left eye. On examination, uncorrected visual acuity (Snellen were 20/100 in the right eye and 20/640 in the left eye with amblyopia. On biomicroscopic examination, there were bilateral dense PPM and cataract in the left eye. Visual field analysis of right and left eyes showed great narrowing of visual fields. We present our case in order to emphasize that analysis of visual field of patients with PPM is as important as central vision when planning its treatment. For planning treatment of patients with PPM, visual impairment, size of pupillary opening, and visual field analysis should be considered.

  16. Phases of dense matter with holographic instantons

    CERN Document Server

    Preis, Florian

    2016-01-01

    We discuss nuclear matter and the transition to quark matter in the decompactified limit of the Sakai-Sugimoto model. Nuclear matter is included through instantons on the flavor branes of the model. Our approximation is based on the flat-space solution, but we allow for a dynamical instanton width and deformation and compute the energetically preferred number of instanton layers in the bulk as a function of the baryon chemical potential. We determine the regions in parameter space where the binding energy of nuclear matter is like in QCD, and compute the phase diagram in the plane of temperature and chemical potential.

  17. Dense film polyimide membranes for aggressive sour gas feed separations

    KAUST Repository

    Kraftschik, Brian

    2013-02-01

    Dense film membranes of the copolyimide 6FDA-DAM:DABA (3:2) are studied for simultaneous removal of CO2 and H2S from sour natural gas streams. Pure and mixed gas permeation as well as pure gas sorption data are reported at 35°C and pressures up to 62bar. The H2S partial pressures used are representative of highly aggressive field operations. Penetrant-induced plasticization effects are evident at feed pressures below 1bar in pure H2S feeds; sub-Tg thermal annealing is used to effectively mitigate this effect, and these annealed films are used throughout the study. Surprisingly, H2S/CH4 selectivity nearly doubles for mixed gas testing in comparison to the pure component ideal selectivity values and approaches the level of a state-of-the-art glassy polymer, cellulose acetate (CA), at H2S partial pressures above 2bar. Furthermore, permeation experiments using a 9.95% H2S, 19.9% CO2, 70.15% CH4 mixture at low feed pressures give CO2/CH4 selectivity of up to 49-over 30% greater than the pure component selectivity for 6FDA-DAM:DABA (3:2). The overall sour gas separation performance of this polyimide is comparable to high-performance rubbery polymer membranes, which have been reported for only moderate H2S partial pressure feeds, and is superior to that for CA based on a practical combined acid gas separation efficiency metric that we introduce. Finally, methods for continued development of the current polyimide membrane material for aggressive sour gas separations are presented. © 2012 Elsevier B.V.

  18. Dense inorganic membranes - studies on transport properties, defect chemistry and catalytic behaviour

    NARCIS (Netherlands)

    Elshof, ten Johan Evert

    1997-01-01

    Oxygen separation with dense oxide membranes may be an attractive method for the production of oxygen from air. Another possible application is the direct supply of oxygen in membrane reactors for the (partial) oxidation of hydrocarbons. The driving force for oxygen permeation through dense mixed io

  19. Gluonic phases, vector condensates, and exotic hadrons in dense QCD

    CERN Document Server

    Gorbar, E V; Miransky, V A; Hashimoto, Michio

    2007-01-01

    We study the dynamics in phases with vector condensates of gluons (gluonic phases) in dense two-flavor quark matter. These phases yield an example of dynamics in which the Higgs mechanism is provided by condensates of gauge (or gauge plus scalar) fields. Because vacuum expectation values of spatial components of vector fields break the rotational symmetry, it is naturally to have a spontaneous breakdown both of external and internal symmetries in this case. In particular, by using the Ginzburg-Landau approach, we establish the existence of a gluonic phase with both the rotational symmetry and the electromagnetic U(1) being spontaneously broken. In other words, this phase describes an anisotropic medium in which the color and electric superconductivities coexist. It is shown that this phase corresponds to a minimum of the Ginzburg-Landau potential and, unlike the two-flavor superconducting (2SC) phase, it does not suffer from the chromomagnetic instability. The dual (confinement) description of its dynamics is...

  20. Phase matching alters spatial multiphoton processes in dense atomic ensembles

    CERN Document Server

    Leszczyński, Adam; Wasilewski, Wojciech

    2016-01-01

    Multiphoton processes in dense atomic vapors such as four-wave mixing or coherent blue light generation are typically viewed from single-atom perspective. Here we study the surprisingly important effect of phase matching near two-photon resonances that arises due to spatial extent of the atomic medium within which the multiphoton process occurs. The non-unit refractive index of the atomic vapor may inhibit generation of light in nonlinear processes, significantly shift the efficiency maxima in frequencies and redirect emitted beam. We present these effects on an example of four-wave mixing in dense rubidium vapors in a double-ladder configuration. By deriving a simple theory that takes into account essential spatial properties of the process, we give precise predictions and confirm their validity in the experiment. The model allows us to improve on the geometry of the experiment and engineer more efficient four-wave mixing.

  1. Phase matching alters spatial multiphoton processes in dense atomic ensembles.

    Science.gov (United States)

    Leszczyński, Adam; Parniak, Michał; Wasilewski, Wojciech

    2017-01-09

    Multiphoton processes in dense atomic vapors such as four-wave mixing or coherent blue light generation are typically viewed from single-atom perspective. Here we study the surprisingly important effect of phase matching near two-photon resonances that arises due to spatial extent of the atomic medium within which the multiphoton process occurs. The non-unit refractive index of the atomic vapor may inhibit generation of light in nonlinear processes, significantly shift the efficiency maxima in frequencies and redirect emitted beam. We present these effects on an example of four-wave mixing in dense rubidium vapors in a double-ladder configuration. By deriving a simple theory that takes into account essential spatial properties of the process, we give precise predictions and confirm their validity in the experiment. The model allows us to improve on the geometry of the experiment and engineer more efficient four-wave mixing.

  2. A Novel Dense Mixed-Conducting Membrane for Oxygen Permeation

    Institute of Scientific and Technical Information of China (English)

    徐南平; 李世光; 金万勤; 时钧

    2000-01-01

    Perovskite type SrCo0.4Fe0.6O3-δ(SCF) membrane and a novel perovskite-related ZrO2 doped SrCo0.4Fe0.6O3-δ(SCFZ) membrane were successfully prepared by isostatic pressing. The sintered membranes were characterized by high-temperature X-ray diffraction (HTXRD) and energy dispersive spectroscopy (EDS). The oxygen permeabilities of membranes have been measured in the temperature range of 923 K to 1243 K. The oxygen permeation flux at 1123K and activation energy of SCFZ membrane with the thickness of 2mm are respectively 2.68×10-7 mol·cm-2·min-1 and 97.76 kJ·mol-1. The results of HTXRD in argon atmosphere and the oxygen permeation experiment indicate that the SCFZ membrane is stable at elevated temperature and low oxygen partial pressure.

  3. Linearly concatenated cyclobutane (ladderane) lipids form a dense bacterial membrane

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Strous, M.; Rijpstra, W.I.C.; Hopmans, E.C.; Geenevasen, J.A.J.; Duin, A.C.T. van; Niftrik, L.A.; Jetten, M.S.M.

    2002-01-01

    Lipid membranes are essential to the functioning of cells, enabling the existence of concentration gradients of ions and metabolites. Microbial membrane lipids can contain three-, five-, six- and even seven-membered aliphatic rings, but four-membered aliphatic cyclobutane rings have never been obser

  4. Prospects and problems of dense oxygen permeable membranes

    DEFF Research Database (Denmark)

    Hendriksen, P.V.; Larsen, P.H.; Mogensen, Mogens Bjerg

    2000-01-01

    The prospects of using mixed ionic/electronic conducting ceramics for syngas production in a catalytic membrane reactor are analysed. Problems relating to limited thermodynamic stability and poor dimensional stability of candidate materials are addressed, The consequences for these problems......, of flux improving measures like minimization of membrane thickness and minimization of the losses due to oxygen exchange over the membrane surfaces, are discussed. The analysis is conducted on two candidate materials: La0.6Sr0.4Co0.2Fe0.8O3-delta and SrFeCo0.5Ox. Finally. experimental investigations...

  5. Structural and dynamical transformations between neighboring dense microemulsion phases

    Science.gov (United States)

    Kotlarchyk, M.; Sheu, E. Y.; Capel, M.

    1992-07-01

    A small-angle x-ray scattering (SAXS) study of dense AOT-water-decane microemulsions [AOT denotes sodium bis(2-ethylhexyl) sulfosuccinate] was undertaken in order to delineate clearly the phase behavior and corresponding structural transitions for AOT-plus-water volume fractions ranging from φ=0.60 to 0.95. Spectra were collected for temperatures between T=3 and 65 °C. The resulting T-vs-φ phase diagram indicates three distinct structural domains when the water-to-AOT molar ratio is fixed at W=40.8, namely, the previously investigated L2 droplet phase, a high-temperature Lα lamellar phase, and a low-temperature L3 phase consisting of randomly connected lamellar sheets. A significantly wide coexistence region accompanies the droplet-to-lamellar phase transition, which is demonstrated to be first order. For W between 15 and 40, an analysis of the lamellar structure using a one-dimensional paracrystal model produces a Hosemann g factor indicative of an approximately constant variation in the lamellar spacing of about 8%. The SAXS study was supplemented by dielectric-relaxation, shear-viscosity, and quasielastic light-scattering measurements in order to substantiate the observed phase transitions and further our understanding of the structural and dynamical properties of the L3 phase. It was found that the L3 phase exhibits Newtonian behavior up to a shear rate of 790 s-1, in contradiction to previous theoretical considerations. The phase exhibits two distinct relaxation modes. A relaxation time of ~1 ms characterizes the Brownian motion of a single lamellar sheet, while the motion of the entire interconnected sheet assembly has a relaxation time on the order of 1 s.

  6. Cooling compact stars and phase transitions in dense QCD

    Energy Technology Data Exchange (ETDEWEB)

    Sedrakian, Armen [J.W. Goethe University, Institute for Theoretical Physics, Frankfurt am Main (Germany)

    2016-03-15

    We report new simulations of cooling of compact stars containing quark cores and updated fits to the Cas A fast cooling data. Our model is built on the assumption that the transient behaviour of the star in Cas A is due to a phase transition within the dense QCD matter in the core of the star. Specifically, the fast cooling is attributed to an enhancement in the neutrino emission triggered by a transition from a fully gapped, two-flavor, red-green color-superconducting quark condensate to a superconducting crystalline or an alternative gapless, color-superconducting phase. The blue-colored condensate is modeled as a Bardeen-Cooper-Schrieffer (BCS)-type color superconductor with spin-one pairing order parameter. We study the sensitivity of the fits to the phase transition temperature, the pairing gap of blue quarks and the timescale characterizing the phase transition (the latter modelled in terms of a width parameter). Relative variations in these parameter around their best-fit values larger than 10{sup -3} spoil the fit to the data. We confirm the previous finding that the cooling curves show significant variations as a function of compact star mass, which allows one to account for dispersion in the data on the surface temperatures of thermally emitting neutron stars. (orig.)

  7. Homogeneous porous perovskite supports for thin dense oxygen separation membranes

    NARCIS (Netherlands)

    Haar, van der L.M.; Verweij, H.

    2000-01-01

    Porous La1−xSrxCoO3−δ substrates (x=0.7, 0.5 and 0.2) were prepared as supports for thin mixed ionic-electronic conducting perovskite membranes. The preparation method is based on pyrolythic powder preparation, followed by high temperature calcination to reduce the sinter activity of the powder. Sub

  8. Prediction of a Low-Dense BC2N Phase

    Institute of Scientific and Technical Information of China (English)

    SHAO Xi

    2011-01-01

    We predict a low-dense phase of ternary boron-carbon-nitrogen compound with a cubic symmetry, named as ldBC2N. Crystal and electronic structures are studied by the ab initio pseudopotential density functional method.Lattice constant, electronic band structure and density of state as well as the phonon spectrum of ld-BC2N are calculated. Our results show that ld-BC2N is an indirect gap semiconductor with a band gap of 3.6eV, a theoretical Vickers hardness of 67.5 GPa and the bulk modulus of 280 GPa suggest that ld-BC2N is a superhard material which has low elastic moduli and high hardness compared with cubic BN.%@@ We predict a low-dense phase of ternary boron-carbon-nitrogen compound with a cubic symmetry,named as ldBC2N.Crystal and electronic structures are studied by the ab initio pseudopotential density functional method.Lattice constant,electronic band structure and density of state as well as the phonon spectrum of ld-BC2N are calculated.Our results show that ld-BC2N is an indirect gap semiconductor with a band gap of 3.6eV,a theoretical Vickers hardness of 67.5 GPa and the bulk modulus of 280 GPa suggest that ld-BC2N is a superhard materialwhich has low elastic moduli and high hardness compared with cubic BN.

  9. Dense pulmonary opacification in neonates treated with extracorporeal membrane oxygenation

    Energy Technology Data Exchange (ETDEWEB)

    Schlesinger, A.E.; Cornish, J.D.; Null, D.M.

    1986-09-01

    Chest radiographic findings in three neonates with respiratory failure secondary to meconium aspiration treated with extracorporeal membrane oxygenation (ECMO) are described. The degree of pulmonary opacification on the chest radiographs failed to correlate with the patients' clinical status as measured by the arterial oxygen levels but correlated well with the peak airway pressure (PAP) and continuous positive airway pressure (CPAP) settings on the mechanical ventilator. Because a variable portion of the arterial blood oxygenation is performed by the extracorporeal membrane oxygenator and unusually large fluctuations in airway pressure settings can occur in these patients while on ECMO, it is important to realize that the chest radiography may not be an accurate predictor of the patients' clinical status.

  10. Inactivation of Pseudomonas aeruginosa biofilm by dense phase carbon dioxide.

    Science.gov (United States)

    Mun, Sungmin; Jeong, Jin-Seong; Kim, Jaeeun; Lee, Youn-Woo; Yoon, Jeyong

    2009-01-01

    Dense phase carbon dioxide (DPCD) is one of the most promising techniques available to control microorganisms as a non-thermal disinfection method. However, no study on the efficiency of biofilm disinfection using DPCD has been reported. The efficiency of DPCD in inactivating Pseudomonas aeruginosa biofilm, which is known to have high antimicrobial resistance, was thus investigated. P. aeruginosa biofilm, which was not immersed in water but was completely wet, was found to be more effectively inactivated by DPCD treatment, achieving a 6-log reduction within 7 min. The inactivation efficiency increased modestly with increasing pressure and temperature. This study also reports that the water-unimmersed condition is one of the most important operating parameters in achieving efficient biofilm control by DPCD treatment. In addition, observations by confocal laser scanning microscopy revealed that DPCD treatment not only inactivated biofilm cells on the glass coupons but also caused detachment of the biofilm following weakening of its structure as a result of the DPCD treatment; this is an added benefit of DPCD treatment.

  11. Dense Membranes for Anode Supported all Perovskite IT-SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Rambabu Bobba

    2006-09-14

    During this first year of the project, a post doctoral fellow (Dr. Hrudananda Jena), and two graduate students (Mr. Vinay B. V. Sivareddy, Aswin Somuru), were supported through this project funds. Also, partial support was provided to three undergraduate students (Jonthan Dooley, India Snowden, Jeremy Gilmore) majoring in Chemistry, Physics, and Engineering disciplines. Various wet chemical methods of synthesis have been attempted to prepare perovskite oxide powders with a hope to improve and engineer its properties to meet the requirements of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFCs) components. Various compounds were synthesized, characterized by XRD, TEM, SEM, XPS, electron microprobe and their electrical transport properties were measured by EIS at elevated temperatures and compared. Sonochemical technique (power of ultra sonic probe 750 watt) combined with hydrothermal treatment of precursors for the preparation of calcium hydroxy apatites (Ca-HAp) was used for the first time. Ca-HAp was substituted with Sr and Mg (50% replacement of Ca in Ca-HAp) to study the effect of substitution on Ca-HAp. Calcium hydroxy apatite is a bioceramic and has potential applications as artificial bone, enamel materials. In this study we tried to investigate its use as proton conductors in PC-SOFC. The properties like electrical conductivity, crystal structure, compositions of CaHAp were studied and compared with the natural bone material. The comparison found to be excellent indicating the efficiency of the preparation techniques. The typical value of conductivity measured is 0.091 x 10{sup -6} Scm{sup -1} at 25 C and 19.26 x 10{sup -6} Scm{sup -1} at 850 C with an applied frequency of 100 kHz. The conductivity increases on increasing frequency and temperature and reaches 0.05mS/cm at 500 C. The crystal structure and phase stability of perovskites as well as apatites were investigated with respect to substitution of various iso-valent and alivalent ions to

  12. Effects of chitosan solution concentration and incorporation of chitin and glycerol on dense chitosan membrane properties.

    Science.gov (United States)

    Dallan, Paula Rulf Marreco; Moreira, Patrícia da Luz; Petinari, Leandro; Malmonge, Sônia Maria; Beppu, Marisa Masumi; Genari, Selma Candelária; Moraes, Angela Maria

    2007-02-01

    The aim of this work was to perform a systematic study about the effects induced by chitosan solution concentration and by chitin or glycerol incorporation on dense chitosan membranes with potential use as burn dressings. The membrane properties analyzed were total raw material cost, thickness, morphology, swelling ratio, tensile strength, percentage of strain at break, crystallinity, in vitro enzymatic degradation with lysozyme, and in vitro Vero cells adhesion. While the use of the most concentrated chitosan solution (2.5% w/w) increased membrane cost, it also improved the biomaterial mechanical resistance and ductility, as well as reduced membrane degradation when exposed for 2 months to lysozyme. The remaining evaluated properties were not affected by initial chitosan solution concentration. Chitin incorporation, on the other hand, reduced the membranes cost, swelling ratio, mechanical properties, and crystallinity, resulting in thicker biomaterials with irregular surface more easily degradable when exposed to lysozyme. Glycerol incorporation also reduced the membranes cost and crystallinity and increased membranes degradability after exposure to lysozyme. Strong Vero cells adhesion was not observed in any of the tested membrane formulations. The overall results indicate that the majority of the prepared membranes meet the performance requirements of temporary nonbiodegradable burn dressings (e.g. adequate values of mechanical resistance and ductility, low values of in vitro cellular adhesion on their surfaces, low extent of degradation when exposed to lysozyme solution, and high stability in aqueous solutions).

  13. Development of Pd Alloy Hydrogen Separation Membranes with Dense/Porous Hybrid Structure for High Hydrogen Perm-Selectivity

    Directory of Open Access Journals (Sweden)

    Jae-Yun Han

    2014-01-01

    Full Text Available For the commercial applications of hydrogen separation membranes, both high hydrogen selectivity and permeability (i.e., perm-selectivity are required. However, it has been difficult to fabricate thin, dense Pd alloy composite membranes on porous metal support that have a pore-free surface and an open structure at the interface between the Pd alloy films and the metal support in order to obtain the required properties simultaneously. In this study, we fabricated Pd alloy hydrogen separation membranes with dense/porous hybrid structure for high hydrogen perm-selectivity. The hydrogen selectivity of this membrane increased owing to the dense and pore-free microstructure of the membrane surface. The hydrogen permeation flux also was remarkably improved by the formation of an open microstructure with numerous open voids at the interface and by an effective reduction in the membrane thickness as a result of the porous structure formed within the Pd alloy films.

  14. Phases of Dense Matter in Supernovae and Neutron Stars

    Institute of Scientific and Technical Information of China (English)

    申虹; 王延楠

    2012-01-01

    We study the properties of dense matter at finite temperature with various proton fractions for use in supernova simulations. The relativistic mean-field theory is used to describe homogeneous nuclear matter, while the Thomas-Fermi approximation is adopted to describe inhomogeneous matter. We also discuss the equation of state of neutron star matter at zero temperature in a wide density range. The equation of state at high densities can be significantly softened by the inclusion of hyperons.

  15. Water and vapor permeability at different temperatures of poly (3-Hydroxybutyrate dense membranes

    Directory of Open Access Journals (Sweden)

    Luiz H. Poley

    2005-03-01

    Full Text Available Polyhydroxyalkanoates (PHAs are polymers produced from renewable resources with biodegradability and biocompatibility, being therefore attractive for medical and pharmaceutical purposes. Poly (3-hydroxybutyrate (PHB is the most important polymer of this family by considering the biotechnology process of its synthesis. In the present study, dense films of PHB were prepared by casting from chloroform solutions (1% m/m. Permeability studies with water, methanol, ethanol and n-propanol were performed using the gravimetric method at different temperatures (from 50 ºC to 65 ºC. Results provide new data on permeability coefficients of PHB membranes.

  16. Strength degradation and failure limits of dense and porous ceramic membrane materials

    DEFF Research Database (Denmark)

    Pećanac, G.; Foghmoes, Søren Preben Vagn; Lipińska-Chwałek, M.;

    2013-01-01

    Thin dense membrane layers, mechanically supported by porous substrates, are considered as the most efficient designs for oxygen supply units used in Oxy-fuel processes and membrane reactors. Based on the favorable permeation properties and chemical stability, several materials were suggested...... as promising membrane and substrate materials: Ba0.5Sr0.5Co0.8Fe0.2O3−δ, La0.6−xSr0.4Co0.2Fe0.8O3−δ (x=0, 0.02) and Ce0.9Gd0.1O1.95−δ. Although membranes operate at elevated temperatures, the ends of tubes in certain three-end concepts remain almost at room temperature. The current work concentrates...... on the failure potential of these membrane parts, where in a complex device also the highest residual stresses should arise due to differences in thermal expansion. In particular, sensitivity of the materials to subcritical crack growth was assessed since the long-term reliability of the component does not only...

  17. Gluonic phase in neutral two-flavor dense QCD

    CERN Document Server

    Gorbar, E V; Miransky, V A; Hashimoto, Michio

    2006-01-01

    In the Ginzburg-Landau approach, we describe a new phase in neutral two-flavor quark matter in which gluonic degrees of freedom play a crucial role. We call it a gluonic phase. In this phase gluonic dynamics cure a chromomagnetic instability in the 2SC solution and lead to spontaneous breakdown of the color gauge symmetry, the electromagnetic U(1), and the rotational SO(3). In other words, the gluonic phase describes an anisotropic medium in which the color and electric superconductivities coexist. Because most of the initial symmetries in this system are spontaneously broken, its dynamics is very rich.

  18. Dense ceramic membranes: A review of the state of the art

    Directory of Open Access Journals (Sweden)

    Kozhukharov, V.

    1999-02-01

    Full Text Available During the past several years the concepts of oxygen permeation through mixed valency ceramic membranes possess special interest. In this context, a classification and brief review of the major membrane ceramic materials will be presented. The focus will be on dense ceramic membranes as elements for advanced application. A discussion will be proposed for mixed conductor ceramics as perovskite ABO3 compounds. Dense membranes on perovskite base are the object of the present review and some details about processing and characterization of double (A- and B-site substituted La1-x Sr(BaxCo0.8Fe0.2O3-d perovskites will be presented.

    El concepto de permeación de oxígeno a través de membranas cerámicas de valencia mixta, ha venido adquiriendo especial relevancia a lo largo de los últimos años. En este contexto se hace se efectúa una clasificación y breve revisión de los materiales cerámicos más relevantes utilizados como membranas. En particular se orienta la descripción hacia las membranas cerámicas densas para aplicaciones avanzadas. Se propone un análisis de los conductores cerámicos mixtos, como los compuestos de tipo perovskita ABO3. Se realiza una revisión de los materiales de este tipo existentes, así como se describen algunos aspectos sobre el procesamiento y caracterización de las perovskitas tipo La1-x Sr(BaxCo0.8Fe0.2O3-d doblemente sustituidas (lugares A- y B-.

  19. Phases of dense matter with non-spherical nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pethick, C.J. [NORDITA, Copenhagen (Denmark)]|[Dept. of Physics, Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States); Ravenhall, D.G. [Dept. of Physics, Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)

    1998-06-01

    A brief review is given of some of the important physics related to phases with non-spherical nuclei that can exist in neutron stars and in matter in stellar collapse at densities just below the saturation density of nuclear matter. Comparisons are made with other systems that exhibit similar liquid-crystal-like phases, both in nuclear physics and in condensed matter physics. A short account is given of recent work on the elastic properties of these phases, and their vibration spectrum, as well as on neutron superfluid gaps. (orig.)

  20. Phase separation in dense glassy liquids: effect of quenching protocols

    Science.gov (United States)

    Chaudhuri, Pinaki; Horbach, Jürgen

    2016-08-01

    Extensive molecular dynamics simulations are used to investigate the phase separation kinetics in a glass-forming binary Lennard-Jones mixture. The focus is on the two-phase region at low temperatures (i.e. below the glass transition line), where coexistence between a low-density gas with a metastable amorphous solid, i.e. a glass occurs. Two different quench paths are chosen to get into the two-phase region starting from a structurally homogeneous state, one along which temperature is lowered at a fixed density, and in the other case, the volume is expanded to reach lower densities at fixed temperatures. Both paths are explored by tuning the rates of cooling or expansion, respectively. We analyze thermodynamic and structural properties of the phase-separating systems, in particular with respect to differences in the morphologies that are obtained from the different quench protocols.

  1. Hadron-quark phase transition in dense stars

    Energy Technology Data Exchange (ETDEWEB)

    Grassi, F.

    1987-10-01

    An equation of state is computed for a plasma of one flavor quarks interacting through some phenomenological potential, at zero temperature. Assuming that the confining potential is scalar and color-independent, it is shown that the quarks undergo a first-order mass phase transition. In addition, due to the way screening is introduced, all the thermodynamic quantities computed are independent of the actual shape of the interquark potential. This equation of state is then generalized to a several quark flavor plasma and applied to the study of the hadron-quark phase transition inside a neutron star. 45 refs., 4 figs.

  2. The Diamagnetic Phase Transition of Dense Electron Gas: Astrophysical Applications

    Science.gov (United States)

    Wang, Zhaojun; Lü, Guoliang; Zhu, Chunhua; Wu, Baoshan

    2016-10-01

    Neutron stars are ideal astrophysical laboratories for testing theories of the de Haas-van Alphen effect and diamagnetic phase transition which is associated with magnetic domain formation. The “magnetic interaction” between delocalized magnetic moments of electrons (the Shoenberg effect), can result in an effect of the diamagnetic phase transition into domains of alternating magnetization (Condon's domains). Associated with the domain formation are prominent magnetic field oscillation and anisotropic magnetic stress which may be large enough to fracture the crust of magnetar with a super-strong field. Even if the fracture is impossible as in “low-field” magnetar, the depinning phase transition of domain wall (DW) motion driven by low field rate (mainly due to the Hall effect) in the randomly perturbed crust can result in a catastrophically variation of magnetic field. This intermittent motion, similar to the avalanche process, makes the Hall effect be dissipative. These qualitative consequences about magnetized electron gas are consistent with observations of magnetar emission, and especially the threshold critical dynamics of driven DW can partially overcome the difficulties of “low-field” magnetar bursts and the heating mechanism of transient, or “outbursting” magnetar.

  3. Rheology and phase behavior of dense casein micelle dispersions

    Science.gov (United States)

    Bouchoux, A.; Debbou, B.; Gésan-Guiziou, G.; Famelart, M.-H.; Doublier, J.-L.; Cabane, B.

    2009-10-01

    Casein micelle dispersions have been concentrated through osmotic stress and examined through rheological experiments. In conditions where the casein micelles are separated from each other, i.e., below random-close packing, the dispersions have exactly the flow and dynamic properties of the polydisperse hard-sphere fluid, demonstrating that the micelles interact only through excluded volume effects in this regime. These interactions cause the viscosity and the elastic modulus to increase by three orders of magnitude approaching the concentration of random-close packing estimated at Cmax≈178 g/l. Above Cmax, the dispersions progressively turn into "gels" (i.e., soft solids) as C increases, with elastic moduli G' that are nearly frequency independent. In this second regime, the micelles deform and/or deswell as C increases, and the resistance to deformation results from the formation of bonds between micelles combined with the intrinsic mechanical resistance of the micelles. The variation in G' with C is then very similar to that observed with concentrated emulsions where the resistance to deformation originates from a set of membranes that separate the droplets. As in the case of emulsions, the G' values at high frequency are also nearly identical to the osmotic pressures required to compress the casein dispersions. The rheology of sodium caseinate dispersions in which the caseins are not structured into micelles is also reported. Such dispersions have the behavior of associative polymer solutions at all the concentrations investigated, further confirming the importance of structure in determining the rheological properties of casein micelle systems.

  4. The flat phase of quantum polymerized membranes

    CERN Document Server

    Coquand, O

    2016-01-01

    We investigate the flat phase of quantum polymerized phantom membranes by means of a nonperturbative renormalization group approach. We first implement this formalism for general quantum polymerized membranes and derive the flow equations that encompass both quantum and thermal fluctuations. We then deduce and analyze the flow equations relevant to study the flat phase and discuss their salient features : quantum to classical crossover and, in each of these regimes, strong to weak coupling crossover. We finally illustrate these features in the context of free standing graphene physics.

  5. Preparation and oxygen permeation properties of SrFe(Cu)O3-δ dense ceramic membranes

    Institute of Scientific and Technical Information of China (English)

    Heng Zhang; Tingting Wang; Xinfa Dong; Weiming Lin

    2009-01-01

    Mixed oxygen-ionic and electronic conducting membranes of SrFe(Cu)O3-δ were prepared by solid-state reaction method.The crystal structure,oxygen nonstoichiometry,and phase stability of the materials were studied by TGA and XRD.Oxygen permeation fluxes through these membranes were studied at operating temperature ranging from 750 to 950 ℃.Results showed that doping Cu in SrFeO3-δ compound had a significant effect on the formation of single-phased perovskite structure.For SrFe1-xCuxO3-δ series materials,the oxygen nonstoichiometry and the oxygen permeation flux increased considerably with the increase of Cu-doping content (x = 0.1-0.3).The sintering property of the membrane decreased significantly when the Cu substitution amount reached 40%.SrFe0.7CU0.3O3-δ showed high oxygen permeation flux,but SrCuO2 and Sr2Fe2O5 phases formed in the compound after oxygen permeation test induced cracks in the membrane.

  6. Dense superconducting phases of copper-bismuth at high pressure

    Science.gov (United States)

    Amsler, Maximilian; Wolverton, Chris

    2017-08-01

    Although copper and bismuth do not form any compounds at ambient conditions, two intermetallics, CuBi and Cu11Bi7 , were recently synthesized at high pressures. Here we report on the discovery of additional copper-bismuth phases at elevated pressures with high densities from ab initio calculations. In particular, a Cu2Bi compound is found to be thermodynamically stable at pressures above 59 GPa, crystallizing in the cubic Laves structure. In strong contrast to Cu11Bi7 and CuBi, cubic Cu2Bi does not exhibit any voids or channels. Since the bismuth lone pairs in cubic Cu2Bi are stereochemically inactive, the constituent elements can be closely packed and a high density of 10.52 g/cm3 at 0 GPa is achieved. The moderate electron-phonon coupling of λ =0.68 leads to a superconducting temperature of 2 K, which exceeds the values observed both in Cu11Bi7 and CuBi, as well as in elemental Cu and Bi.

  7. Towards the phase diagram of dense two-color matter

    CERN Document Server

    Cotter, Seamus; Hands, Simon; Skullerud, Jon-Ivar

    2012-01-01

    We study two-color QCD with two flavors of Wilson fermion as a function of quark chemical potential mu and temperature T. We find evidence of a superfluid phase at intermediate mu and low T where the quark number density and diquark condensate are both very well described by a Fermi sphere of nearly-free quarks disrupted by a BCS condensate. Our results suggest that the quark contribution to the energy density is negative (and balanced by a positive gauge contribution), although this result is highly sensitive to details of the energy renormalisation. We also find evidence that the chiral condensate in this region vanishes in the massless limit. This region gives way to a region of deconfined quark matter at higher T and mu, with the deconfinement temperature, determined from the renormalised Polyakov loop, decreasing only very slowly with increasing chemical potential. The quark number susceptibility chi_q does not exhibit any qualitative change at the deconfinement transition. We argue that this is because ...

  8. IMPROVED SUBGRID SCALE MODEL FOR DENSE TURBULENT SOLID-LIQUID TWO-PHASE FLOWS

    Institute of Scientific and Technical Information of China (English)

    TANG Xuelin; QIAN Zhongdong; WU Yulin

    2004-01-01

    The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules. Assuming that the solid-phase velocity distributions obey the Maxwell equations, the collision term for particles under dense two-phase flow conditions is also derived.In comparison with the governing equations of a dilute two-phase flow, the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations. Based on Cauchy-Helmholtz theorem and Smagorinsky model,a second-order dynamic sub-grid-scale (SGS) model, in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor, is proposed to model the two-phase governing equations by applying dimension analyses. Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls, the velocity and pressure fields, and the volumetric concentration are calculated. The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.

  9. Membranes as separators of dispersed emulsion phases

    NARCIS (Netherlands)

    Lefferts, A.G.

    1997-01-01

    The reuse or discharge of industrial waste waters, containing small fractions of dispersed oil, requires a purification treatment for which membranes can be used. If only little oil is present, removal of the dispersed phase might be preferable to the more commonly applied removal of the

  10. ORGANIC PERMSELECTIVE PERVAPORATION CHARACTERISTICS OF POLY(SILYLPROPYNE) AND COPOLYMER DENSE MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    WANG Xinwei; SHI Yanqiao; CHEN Guanwen

    1997-01-01

    An investigation into the organic permselective separation through poly [1-trimethylsilyl1-propyne] (PTMSP) and (1-trimethylsily1)-1-(1-penta-methyl-disilyl)-l-propyne copolymer (TMSP-PMDSP) dense membranes was made to gain an insight into the effect of the chemical structure of membrane materials on pervaporation (PV) characteristics. The results show that the copolymer has a higher separation factor αorg/water but with a relatively Lower value of flux Jt(g/m2·h)than pure PTMSP.This phenomenon may be attributed to the introduction of side chain with large bulk volume in copolymer, which brought about a decrease of excess free volume and the improvement of diffusion selectivity to some extent. With the same molar concentration of organic liquids in feed, THF/water solutions have the highest value of αorg/water as well as Jt in comparison with ethanol/water,iso-propanol/water and THF/water mixtures.

  11. Synthesis and characterization of gallium-based perovskitetype dense membrane with oxygen semipermeability

    Institute of Scientific and Technical Information of China (English)

    丛铀; 邵宗平; 杨维慎; 熊国兴; 林励吾

    2001-01-01

    La0.15Sr0.85Ga0.3Fe0.7O3-δ(LSGFO) and La0.15Sr0.85Co0.3Fe0.7O3-δ(LSCFO) mixed oxygen-ion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding dense membranes were fabricated. The properties of the oxide powders and membranes were characterized with combined SEM, XRD, H2-TPR, O2-TPD techniques, mechanical strength and oxygen permeation measurement. The results showed that LSGFO had much higher thermochemical stability than LSCFO due to the higher valence stability of Ga3+. After the temperature-programmed reduction by 5% H2 in Ar from 20℃to 1020℃, the basic perovskite structure of LSGFO was successfully preserved. LSGFO also favors the oxygen vacancy formation better than LSCFO. Oxygen permeation measurement demonstrated that LSGFO had higher oxygen permeation flux than LSCFO, but they had similar activation energy for oxygen transportation, with a value of 110 and 117 kJ ?mol-1, respectively. The difference in oxygen permeation f

  12. Synthesis and characterization of gallium-based perovskite- type dense membrane with oxygen semipermeability

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    La0.15Sr0.85Ga0.3Fe0.7O3-d (LSGFO) and La0.15Sr0.85Co0.3Fe0.7O3-d (LSCFO) mixed oxygen-ion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding dense membranes were fabricated. The properties of the oxide powders and membranes were characterized with combined SEM, XRD, H2-TPR, O2-TPD techniques, mechanical strength and oxygen permeation measurement. The results showed that LSGFO had much higher thermochemical stability than LSCFO due to the higher valence stability of Ga3+. After the temperature-programmed reduction by 5% H2 in Ar from 20℃ to 1020℃, the basic perovskite structure of LSGFO was successfully preserved. LSGFO also favors the oxygen vacancy formation better than LSCFO. Oxygen permeation measurement demonstrated that LSGFO had higher oxygen permeation flux than LSCFO, but they had similar activation energy for oxygen transportation, with a value of 110 and 117 kJ omol-1, respectively. The difference in oxygen permeation fluxes was correlated with the difference in oxygen vacancy concentrations for the two materials.

  13. Towards the heavy dense QCD phase diagram using Complex Langevin simulations

    CERN Document Server

    Aarts, Gert; Jäger, Benjamin; Seiler, Erhard; Sexty, Dénes; Stamatescu, Ion-Olimpiu

    2015-01-01

    Monte Carlo methods cannot probe far into the QCD phase diagram with a real chemical potential, due to the famous sign problem. Complex Langevin simulations, using adaptive step-size scaling and gauge cooling, are suited for sampling path integrals with complex weights. We report here on tests of the deconfinement transition in pure Yang-Mills SU(3) simulations and present an update on the QCD phase diagram in the limit of heavy and dense quarks.

  14. Results on the heavy-dense QCD phase diagram using complex Langevin

    CERN Document Server

    Aarts, Gert; Jäger, Benjamin; Sexty, Dénes

    2016-01-01

    Complex Langevin simulations have been able to successfully reproduce results from Monte Carlo methods in the region where the sign problem is mild and make predictions when it is exponentially hard. We present here our study of the QCD phase diagram and the boundary between the confined and deconfined phases in the limit of heavy and dense quarks (HDQCD) for 3 different lattice volumes. We also briefly discuss instabilities encountered in our simulations.

  15. Carbon molecular sieve dense film membranes derived from Matrimid® for ethylene/ethane separation

    KAUST Repository

    Rungta, Meha

    2012-04-01

    Development of dense film carbon molecular sieve (CMS) membranes for ethylene/ethane (C 2H 4/C 2H 6) separation is reported. A commercial polyimide, Matrimid®, was pyrolyzed under vacuum and inert argon atmosphere, and the resultant CMS films were characterized using pure C 2H 4 and C 2H 6 permeation at 35 °C, 50 psia feed pressure. The effects on C 2H 4/C 2H 6 separation caused by different final vacuum pyrolysis temperatures from 500 to 800 °C are reported. For all pyrolysis temperatures separation surpassed the estimated \\'upper bound\\' solution processable polymer line for C 2H 4 permeability vs. C 2H 4/C 2H 6 selectivity. C 2H 4 permeability decreased and selectivity increased with increasing pyrolysis temperature until 650-675 °C where an optimum combination of C 2H 4 permeability ∼14-15 Barrer with C 2H 4/C 2H 6 selectivity ∼12 was observed. A modified heating rate protocol for 675 °C showed further increase in permeability with no selectivity loss. CMS films produced from argon pyrolysis showed results comparable to vacuum pyrolysis. Further, mixed gas (63.2 mol% C 2H 4 + 36.8 mol% C 2H 6) permeation showed a slightly lower C 2H 4 permeability with C 2H 4/C 2H 6 selectivity increase rather than a decrease that is often seen with polymers. The high selectivity of these membranes was shown to arise from a high \\'entropic selection\\' indicating that the \\'slimmer\\' ethylene molecule has significant advantage over ethane in passing through the rigid \\'slit-shaped\\' CMS pore structure. © 2011 Elsevier Ltd. All rights reserved.

  16. Desalination membranes from functional block copolymer via non-solvent induced phase inversion

    Science.gov (United States)

    Sung, Hyemin; Poelma, Justin; Leibfarth, Frank; Hawker, Craig; Bang, Joona

    2012-02-01

    Commercially available reverse osmosis (RO) and forward osmosis (FO) membranes are most commonly derived from materials such as polysulfone, polyimide, and cellulose acetate. While these membranes have improved the efficiency of the desalination process, they suffer from mechanical and chemical stability, fouling issues, and low fluxes. In this study, we combine a well-established membrane formation method, non-solvent-induced phase separation, with the self-assembly of a functional amphiphilic block copolymersAn amine and acid functional polystyrene-block-poly(ethylene oxide-co-allyl glycidyl ether) were chosen for the membranes. Membranes were formed by casting a concentrated polymer solution (12 to 25 wt% polymer) on PET fabric followed by immersion in a non-solvent bath. Scanning electron microscopy revealed an asymmetric porous structure consisting of a dense skin layer on top of a highly porous layer. Membrane performance was investigating using an FO test cell under the seawater condition.

  17. Raman measurements of phase transitions in dense solid hydrogen and deuterium to 325 GPa.

    Science.gov (United States)

    Zha, Chang-sheng; Cohen, R E; Mao, Ho-kwang; Hemley, Russell J

    2014-04-01

    Raman spectroscopy of dense hydrogen and deuterium performed to 325 GPa at 300 K reveals previously unidentified transitions. Detailed analysis of the spectra from multiple experimental runs, together with comparison with previous infrared and Raman measurements, provides information on structural modifications of hydrogen as a function of density through the I-III-IV transition sequence, beginning near 200 GPa at 300 K. The data suggest that the transition sequence at these temperatures proceeds by formation of disordered stacking of molecular and distorted layers. Weaker spectral changes are observed at 250, 285, and 300 GPa, that are characterized by discontinuities in pressure shifts of Raman frequencies, and changes in intensities and linewidths. The results indicate changes in structure and bonding, molecular orientational order, and electronic structure of dense hydrogen at these conditions. The data suggest the existence of new phases, either variations of phase IV, or altogether new structures.

  18. New phase diagrams for dense carbon-oxygen mixtures and white dwarf evolution

    CERN Document Server

    Althaus, Leandro G; Isern, Jordi; Córsico, Alejandro H; Bertolami, Marcelo M Miller

    2011-01-01

    Cool white dwarfs are reliable and independent stellar chronometers. The most common white dwarfs have carbon-oxygen dense cores. Consequently, the cooling ages of very cool white dwarfs sensitively depend on the adopted phase diagram of the carbon-oxygen binary mixture. A new phase diagram of dense carbon-oxygen mixtures appropriate for white dwarf interiors has been recently obtained using direct molecular dynamics simulations. In this paper, we explore the consequences of this phase diagram in the evolution of cool white dwarfs. To do this we employ a detailed stellar evolutionary code and accurate initial white dwarf configurations, derived from the full evolution of progenitor stars. We use two different phase diagrams, that of Horowitz et al. (2010), which presents an azeotrope, and the phase diagram of Segretain & Chabrier (1993), which is of the spindle form. We computed the evolution of 0.593 and 0.878M_sun white dwarf models during the crystallization phase, and we found that the energy released...

  19. Conformational phases of membrane bound cytoskeletal filaments

    Science.gov (United States)

    Quint, David A.; Grason, Gregory; Gopinathan, Ajay

    2013-03-01

    Membrane bound cytoskeletal filaments found in living cells are employed to carry out many types of activities including cellular division, rigidity and transport. When these biopolymers are bound to a membrane surface they may take on highly non-trivial conformations as compared to when they are not bound. This leads to the natural question; What are the important interactions which drive these polymers to particular conformations when they are bound to a surface? Assuming that there are binding domains along the polymer which follow a periodic helical structure set by the natural monomeric handedness, these bound conformations must arise from the interplay of the intrinsic monomeric helicity and membrane binding. To probe this question, we study a continuous model of an elastic filament with intrinsic helicity and map out the conformational phases of this filament for various mechanical and structural parameters in our model, such as elastic stiffness and intrinsic twist of the filament. Our model allows us to gain insight into the possible mechanisms which drive real biopolymers such as actin and tubulin in eukaryotes and their prokaryotic cousins MreB and FtsZ to take on their functional conformations within living cells.

  20. Complexation-Induced Phase Separation: Preparation of Metal-Rich Polymeric Membranes

    KAUST Repository

    Villalobos Vazquez de la Parra, Luis Francisco

    2017-08-01

    The majority of state-of-the-art polymeric membranes for industrial or medical applications are fabricated by phase inversion. Complexation induced phase separation (CIPS)—a surprising variation of this well-known process—allows direct fabrication of hybrid membranes in existing facilities. In the CIPS process, a first step forms the thin metal-rich selective layer of the membrane, and a succeeding step the porous support. Precipitation of the selective layer takes place in the same solvent used to dissolve the polymer and is induced by a small concentration of metal ions. These ions form metal-coordination-based crosslinks leading to the formation of a solid skin floating on top of the liquid polymer film. A subsequent precipitation in a nonsolvent bath leads to the formation of the porous support structure. Forming the dense layer and porous support by different mechanisms while maintaining the simplicity of a phase inversion process, results in unprecedented control over the final structure of the membrane. The thickness and morphology of the dense layer as well as the porosity of the support can be controlled over a wide range by manipulating simple process parameters. CIPS 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. The nature of the CIPS process facilitates a precise loading of a high concentration of metal ions that are located in only the top layer of the membrane. Moreover, these metal ions can be converted—during the membrane fabrication process—to nanoparticles or crystals. This simple method opens up fascinating possibilities for the fabrication of metal-rich polymeric membranes with a new set of properties. This dissertation describes the process in depth and explores promising

  1. Study on the Motion state of Powdery materials in Dense-phase Pneumatic Conveying Pipe

    Directory of Open Access Journals (Sweden)

    Lia Zhihua

    2016-01-01

    Full Text Available Using the method of computational fluid dynamics, a model is created about powdery materials flowing in the dense-phase pneumatic conveying pipe. the motion state powdery materials flowing in the horizontal and vertical pipe is simulated. It is found that in the horizontal pipe the powdery materials represent the flow of dune-like state, and continuously move forward in this form, the volume fraction of powdery materials at the pipe's bottom is large, the velocity is low; In the vertical pipe, the columnar solid-plug can form and scatter continuously, and the motion state is closer to fluidization.

  2. Synthesis and characterization of dense membranes of silk fibroin with glycerin;Sintese e caracterizacao de membranas densas de fibroina de seda com glicerina

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Mariana F.; Moraes, Mariana A. de; Weska, Raquel F.; Nogueira, Grinia M.; Beppu, Marisa M., E-mail: beppu@feq.unicamp.b [Universidade Estadual de Campinas (FEQ/UNICAMP), SP (Brazil). Faculdade de Engenharia Quimica

    2009-07-01

    The addition of plasticizers seeks improvements in mechanical properties of dense membranes of silk fibroin with possible interactions by hydrogen bonds. The aim of the present study was to produce and characterize dense membranes of silk fibroin containing glycerin in two different concentrations. The characterization of the membranes was performed from scanning electron microscopy (SEM), mechanical traction tests, infrared spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results indicated that the addition of glycerin allowed obtaining homogeneous and more crystalline membranes and improved their properties of elongation. (author)

  3. Magnetic Phase Diagram of Dense Holographic Multiquarks in the Quark-gluon Plasma

    CERN Document Server

    Burikham, Piyabut

    2011-01-01

    We study phase diagram of the dense holographic gauge matter in the Sakai-Sugimoto model in the presence of the magnetic field above the deconfinement temperature. Even above the deconfinement, quarks could form colour bound states through the remaining strong interaction if the density is large. We demonstrate that in the presence of the magnetic field for a sufficiently large baryon density, the multiquark-pion gradient (MQ-$\\mathcal{5}\\phi$) phase is more thermodynamically preferred than the chiral-symmetric quark-gluon plasma. The phase diagrams between the holographic multiquark and the chiral-symmetric quark-gluon plasma phase are obtained at finite temperature and magnetic field. In the mixed MQ-$\\mathcal{5}\\phi$ phase, the pion gradient induced by the external magnetic field is found to be a linear response for small and moderate field strengths. Its population ratio decreases as the density is raised and thus the multiquarks dominate the phase. Temperature dependence of the baryon chemical potential,...

  4. Phase diagram of dense two-color QCD within lattice simulations

    Science.gov (United States)

    Braguta, V. V.; Ilgenfritz, E.-M.; Kotov, A. Yu.; Molochkov, A. V.; Nikolaev, A. A.

    2017-03-01

    We present the results of a low-temperature scan of the phase diagram of dense two-color QCD with Nf = 2 quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point μ = mπ/2 we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with nonzero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase the system is still in confinement, chiral symmetry is restored and the system is very similar to the quarkyonic state predicted by SU(Nc) theory at large Nc.

  5. Study of the phase diagram of dense two-color QCD within lattice simulation

    CERN Document Server

    Braguta, V V; Kotov, A Yu; Molochkov, A V; Nikolaev, A A

    2016-01-01

    In this paper we carry out a low-temperature scan of the phase diagram of dense two-color QCD with $N_f=2$ quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point $\\mu = m_{\\pi}/2$ we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with nonzero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase t...

  6. Structural, chemical surface and transport modifications of regenerated cellulose dense membranes due to low-dose {gamma}-radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, M.I. [Grupo de Caracterizacion Electrocinetica en Membranas e Interfases, Departamento de Fisica Aplicada I, Facultad de Ciencias, Universidad de Malaga, E-29071 Malaga (Spain); Heredia-Guerrero, J.A., E-mail: jose.alejandro@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-Universidad de Sevilla, Avda, Americo Vespuccio 49, 41092 Sevilla (Spain); Galan, P. [Grupo de Caracterizacion Electrocinetica en Membranas e Interfases, Departamento de Fisica Aplicada I, Facultad de Ciencias, Universidad de Malaga, E-29071 Malaga (Spain); Benitez, J.J. [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-Universidad de Sevilla, Avda, Americo Vespuccio 49, 41092 Sevilla (Spain); Benavente, J. [Grupo de Caracterizacion Electrocinetica en Membranas e Interfases, Departamento de Fisica Aplicada I, Facultad de Ciencias, Universidad de Malaga, E-29071 Malaga (Spain)

    2011-04-15

    Research highlights: {yields} Low dose {gamma}-radiation causes slight structural, chemical and morphological changes on regenerated cellulose films. {yields} Induced structural changes increase the fragility of irradiated films. {yields} Structural modifications reduce ion permeability of films. - Abstract: Modifications caused in commercial dense regenerated cellulose (RC) flat membranes by low-dose {gamma}-irradiation (average photons energy of 1.23 MeV) are studied. Slight structural, chemical and morphological surface changes due to irradiation in three films with different RC content were determined by ATR-FTIR, XRD, XPS and AFM. Also, the alteration of their mechanical elasticity has been studied. Modification of membrane performance was determined from solute diffusion coefficient and effective membrane fixed charge concentration obtained from NaCl diffusion measurements. Induced structural changes defining new and effective fracture propagation directions are considered to be responsible for the increase of fragility of irradiated RC membranes. The same structural changes are proposed to explain the reduction of the membrane ion permeability through a mechanism involving either ion pathways elongation and/or blocking.

  7. Cytoskeletal pinning controls phase separation in multicomponent lipid membranes.

    Science.gov (United States)

    Arumugam, Senthil; Petrov, Eugene P; Schwille, Petra

    2015-03-10

    We study the effect of a minimal cytoskeletal network formed on the surface of giant unilamellar vesicles by the prokaryotic tubulin homolog, FtsZ, on phase separation in freestanding lipid membranes. FtsZ has been modified to interact with the membrane through a membrane targeting sequence from the prokaryotic protein MinD. FtsZ with the attached membrane targeting sequence efficiently forms a highly interconnected network on membranes with a concentration-dependent mesh size, much similar to the eukaryotic cytoskeletal network underlying the plasma membrane. Using giant unilamellar vesicles formed from a quaternary lipid mixture, we demonstrate that the artificial membrane-associated cytoskeleton, on the one hand, suppresses large-scale phase separation below the phase transition temperature, and, on the other hand, preserves phase separation above the transition temperature. Our experimental observations support the ideas put forward in our previous simulation study: In particular, the picket fence effect on phase separation may explain why micrometer-scale membrane domains are observed in isolated, cytoskeleton-free giant plasma membrane vesicles, but not in intact cell membranes. The experimentally observed suppression of large-scale phase separation much below the transition temperatures also serves as an argument in favor of the cryoprotective role of the cytoskeleton. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  8. SECOND-ORDER MOMENT MODEL FOR DENSE TWO-PHASE TURBULENT FLOW OF BINGHAM FLUID WITH PARTICLES

    Institute of Scientific and Technical Information of China (English)

    ZENG Zhuo-xiong; ZHOU Li-xing; LIU Zhi-he

    2006-01-01

    The USM-θ model of Bingham fluid for dense two-phase turbulent flow was developed, which combines the second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. In this model, phases interaction and the extra term of Bingharn fluid yield stress are taken into account. An algorithm for USM-θ model in dense two-phase flow was proposed, in which the influence of particle volume fraction is accounted for. This model was used to simulate turbulent flow of Bingham fluid single-phase and dense liquid-particle two-phase in pipe. It is shown USM-θ model has better prediction result than the five-equation model, in which the particle-particle collision is modeled by the particle kinetic theory, while the turbulence of both phase is simulated by the two-equation turbulence model. The USM-θ model was then used to simulate the dense two-phase turbulent up flow of Bingham fluid with particles. With the increasing of the yield stress, the velocities of Bingham and particle decrease near the pipe centre. Comparing the two-phase flow of Bingham-particle with that of liquid-particle, it is found the source term of yield stress has significant effect on flow.

  9. Asymmetric polymeric membranes containing a metal-rich dense layer with a controlled thickness and method of making same

    KAUST Repository

    Peinemann, Klaus-Viktor

    2016-01-21

    A structure, and methods of making the structure are provided in which the structure can include: a membrane having a first layer and a second layer, the first layer comprising polymer chains formed with coordination complexes with metal ions, and the second layer consisting of a porous support layer formed of polymer chains substantially, if not completely, lacking the presence of metal ions. The structure can be an asymmetric polymeric membrane containing a metal-rich layer as the first layer. In various embodiments the first layer can be a metal-rich dense layer. The first layer can include pores. The polymer chains of the first layer can be closely packed. The second layer can include a plurality of macro voids and can have an absence of the metal ions of the first layer.

  10. Pro-apoptotic Bax molecules densely populate the edges of membrane pores.

    Science.gov (United States)

    Kuwana, Tomomi; Olson, Norman H; Kiosses, William B; Peters, Bjoern; Newmeyer, Donald D

    2016-06-03

    How the pro-apoptotic Bax protein permeabilizes the mitochondrial outer membrane is not fully understood. Previously, using cryo-electron microscopy (cryo-EM), we showed that activated Bax forms large, growing pores. Whether formed in liposomes or in mitochondrial outer membranes, Bax-induced pores exhibit the same morphology, with negative curvature flanking the edges and with no visible protein structure protruding from the membranes. Here we used cryo-EM to show that gold-labeled Bax molecules, after activation by Bid, became localized strictly at pore edges. This argues that Bax acts at short range to deform the membrane. Also, Bax molecules populated the walls of both small and large pores at the same density, implying that Bax is continuously recruited to the pores as they widen. Moreover, because all Bax molecules became oligomerized after membrane insertion, we infer that Bax oligomers are present at pore edges. We suggest that oligomerization may promote pore enlargement.

  11. Effects of Phase Separation Behavior on Morphology and Performance of Polycarbonate Membranes

    Directory of Open Access Journals (Sweden)

    Alamin Idris

    2017-04-01

    Full Text Available The phase separation behavior of bisphenol-A-polycarbonate (PC, dissolved in N-methyl-2-pyrrolidone and dichloromethane solvents in coagulant water, was studied by the cloud point method. The respective cloud point data were determined by titration against water at room temperature and the characteristic binodal curves for the ternary systems were plotted. Further, the physical properties such as viscosity, refractive index, and density of the solution were measured. The critical polymer concentrations were determined from the viscosity measurements. PC/NMP and PC/DCM membranes were fabricated by the dry-wet phase inversion technique and characterized for their morphology, structure, and thermal stability using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. The membranes’ performances were tested for their permeance to CO2, CH4, and N2 gases at 24 ± 0.5 °C with varying feed pressures from 2 to 10 bar. The PC/DCM membranes appeared to be asymmetric dense membrane types with appreciable thermal stability, whereas the PC/NMP membranes were observed to be asymmetric with porous structures exhibiting 4.18% and 9.17% decrease in the initial and maximum degradation temperatures, respectively. The ideal CO2/N2 and CO2/CH4 selectivities of the PC/NMP membrane decreased with the increase in feed pressures, while for the PC/DCM membrane, the average ideal CO2/N2 and CO2/CH4 selectivities were found to be 25.1 ± 0.8 and 21.1 ± 0.6, respectively. Therefore, the PC/DCM membranes with dense morphologies are appropriate for gas separation applications.

  12. A detailed investigation of proposed gas-phase syntheses of ammonia in dense interstellar clouds

    Science.gov (United States)

    Herbst, Eric; Defrees, D. J.; Mclean, A. D.

    1987-01-01

    The initial reactions of the Herbst and Klemperer (1973) and the Dalgarno (1974) schemes (I and II, respectively) for the gas-phase synthesis of ammonia in dense interstellar clouds were investigated. The rate of the slightly endothermic reaction between N(+) and H2 to yield NH(+) and H (scheme I) under interstellar conditions was reinvestigated under thermal and nonthermal conditions based on laboratory data. It was found that the relative importance of this reaction in synthesizing ammonia is determined by how the laboratory data at low temperature are interpreted. On the other hand, the exothermic reaction between N and H3(+) to form NH2(+) + H (scheme II) was calculated to possess significant activation energy and, therefore, to have a negligible rate coefficient under interstellar conditions. Consequently, this reaction cannot take place appreciably in interstellar clouds.

  13. Conceptual Design of an Ultra-Dense Phase Injector and Feed System

    Energy Technology Data Exchange (ETDEWEB)

    Ken Sprouse; Fred Widman; Alan Darby

    2006-03-30

    Pratt & Whitney Rocketdyne (PWR) has developed an innovative gasifier concept that uses rocket engine technology to significantly improve gasifier performance, life, and cost compared to current state-of-the-art systems. One key feature of the PWR concept is the use of an ultra-dense phase feed system to provide dry coal to the multi-element injector. This report describes the design of an ultra-dense phase multi-element injector and feed system for use on PWR gasifiers operating at pressures to 1,000 psia. For the design of this injector and feed system, the pulverized coal's Bingham fluid yield stress is approximately 11 Pascals (Pa) with a coefficient of rigidity of 10 centipoise (cp). These values are typical of earlier experimental testing conducted with dried pulverized coal below 18 wt% moisture -- see, e.g., Sprouse and Schuman (1983, 1986). Each individual injector element is designed for a coal flow rate between 3 and 4 tons/hr (0.76 to 1.0 kg/sec) at full flow conditions. Hence, a small 400 to 500 tons/day (4.2 to 5.25 kg/sec) gasifier will require a 6-element injector, a 1,500 tons/day (15.7 kg/sec) gasifier will require an 18-element injector and a 3,000 tons/day (31.5 kg/sec) gasifier will require a 36-element injector. These injectors and feed systems are capable of 'turn-down' below 50% of full-flow operation.

  14. Membrane curvature enables N-Ras lipid anchor sorting to liquid-ordered membrane phases

    DEFF Research Database (Denmark)

    Larsen, Jannik Bruun; Jensen, Martin Borch; Bhatia, Vikram Kjøller;

    2015-01-01

    Trafficking and sorting of membrane-anchored Ras GTPases are regulated by partitioning between distinct membrane domains. Here, in vitro experiments and microscopic molecular theory reveal membrane curvature as a new modulator of N-Ras lipid anchor and palmitoyl chain partitioning. Membrane...... curvature was essential for enrichment in raft-like liquid-ordered phases; enrichment was driven by relief of lateral pressure upon anchor insertion and most likely affects the localization of lipidated proteins in general....

  15. Electrospinning of PVDF nanofibrous membranes with controllable crystalline phases

    Science.gov (United States)

    Lei, Tingping; Zhu, Ping; Cai, Xiaomei; Yang, Le; Yang, Fan

    2015-07-01

    Effectively controlling crystalline phases of electrospun polyvinylidene fluoride (PVDF) nanofibers is crucial to produce membranes with special properties for specific applications. Here, the heating treatment during or after electrospinning has been investigated to determine an effective way to control crystalline phase of PVDF nanofibers. By simultaneously controlling the collector temperature and the flow rate during the fiber deposition, a comparatively lower temperature (≤70 °C) is required for obtaining α-, β-, or γ-phase-dominant nanofibrous membranes, whereas a much higher temperature (≥150 °C) is necessary for post-heating of already-deposited fibers. On the other hand, through finely tuning the heating during or after electrospinning, crosslinked nanofibrous membranes can be also obtained, which undoubtedly enhance mechanical performance of the membranes. Therefore, it is hopeful to fabricate high-performance electrospun PVDF nanofibrous membranes with synchronous control of crystalline phases and morphologies, which will further broaden the applications of PVDF materials.

  16. Synthesis of Dense BC3 Phases under High-Pressure and High-Temperature

    Science.gov (United States)

    Zinin, P.; Ming, L.; Acosta, T.; Jia, R.; Hellebrand, E.; Ishii, H.

    2010-12-01

    The finding of the new diamond-like B-C phases is of fundamental importance. These phases are potential high-temperature superconductors and their development is important for understanding the nature of high-temperature superconductivity (Moussa, Cohen, Phys. Rev. B, 77, 064518 2008). They will shed light on the nature of the bonding of the boron atoms in a diamond-like structure. Recently, theoretical simulations of pressure- and temperature-induced phase transition in the B-C system demonstrated that the incorporation of B atoms into a diamond structure should not lead to a drastic distortion of the cubic cell of a diamond (Lowther, J. Phys. Condense Matter. 17, 3221, 2005). In this report we present data on the synthesis of new dense phases cubic BC3 (c-BC3) phase from graphitic BC3 phase (g-BC3) phase under high pressure and high temperature. Two graphitic polycrystalline BCx samples were compressed in a diamond-anvil cell to about 24 GPa and 45 GPa, respectively, and then were laser-heated to ~2000 K. After quenching, each sample was decompressed gradually stepwise to the atmospheric pressure. Synchrotron-based X-ray diffraction patterns were taken before and after the laser-heating, and also at each pressure step-down. The experimental data showed that two new phases were synthesized: (a) an orthorhombic phase with a0 = 3.74 Å, b0 = 3.24 Å, c0=4.25 Å; and (b) a cubic phase with a0 = 3.587Å recovered from 24 GPa and 44 GPa, respectively. The zero-pressure lattice parameter of the cubic phase obtained in this study is larger than that of diamond (i.e., a0=3.5667 Å, ASTM # 6-0675), which is consistent with theoretical prediction The micro-Raman measurements were directly performed on the new phases. The Raman spectra excited by a green (Nd-YAG, 532-nm) laser were taken with a confocal Raman system (WiTec alpha300). The Raman spectrum of the c-BC3 phase is similar to that of diamond-like BC3 phase (Zinin et al., J. Raman Spectrosc., 38, 1362, 2007) with a

  17. Thermotropic and barotropic phase transitions on diacylphosphatidylethanolamine bilayer membranes.

    Science.gov (United States)

    Matsuki, Hitoshi; Endo, Shigeru; Sueyoshi, Ryosuke; Goto, Masaki; Tamai, Nobutake; Kaneshina, Shoji

    2017-07-01

    The bilayer phase transitions of four diacylphosphatidylethanolamines (PEs) with matched saturated acyl chains (Cn=12, 14, 16 and 18) and two PEs with matched unsaturated acyl chains containing a different kind of double bonds were observed by differential scanning calorimetry under atmospheric pressure and light-transmittance measurements under high pressure. The temperature-pressure phase diagrams for these PE bilayer membranes were constructed from the obtained phase-transition data. The saturated PE bilayer membranes underwent two different phase transitions related to the liquid crystalline (Lα) phase, the transition from the hydrated crystalline (Lc) phase and the chain melting (gel (Lβ) to Lα) transition, depending on the thermal history. Pressure altered the gel-phase stability of the bilayer membranes of PEs with longer chains at a low pressure. Comparing the thermodynamic quantities of the saturated PE bilayer membranes with those of diacylphosphatidylcholine (PC) bilayer membranes, the PE bilayer membranes showed higher phase-transition temperatures and formed more stable Lc phase, which originates from the strong interaction between polar head groups of PE molecules. On the other hand, the unsaturated PE bilayer membranes underwent the transition from the Lα phase to the inverted hexagonal (HII) phase at a high temperature and this transition showed a small transition enthalpy but high pressure-responsivity. It turned out that the kind of double bonds markedly affects both bilayer-bilayer and bilayer-nonbilayer transitions and the Lα/HII transition is a volume driven transition for the reconstruction of molecular packing. Further, the phase-transition behavior was explained by chemical potential curves of bilayer phases. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Glycans pattern the phase behaviour of lipid membranes

    Science.gov (United States)

    Subramaniam, Anand Bala; Guidotti, Guido; Manoharan, Vinothan N.; Stone, Howard A.

    2013-02-01

    Hydrated networks of glycans (polysaccharides)—in the form of cell walls, periplasms or gel-like matrices—are ubiquitously present adjacent to cellular plasma membranes. Yet, despite their abundance, the function of glycans in the extracellular milieu is largely unknown. Here we show that the spatial configuration of glycans controls the phase behaviour of multiphase model lipid membranes: inhomogeneous glycan networks stabilize large lipid domains at the characteristic length scale of the network, whereas homogeneous networks suppress macroscopic lipid phase separation. We also find that glycan-patterned phase separation is thermally reversible—thus indicating that the effect is thermodynamic rather than kinetic—and that phase patterning probably results from a preferential interaction of glycans with ordered lipid phases. These findings have implications for membrane-mediated transport processes, potentially rationalize long-standing observations that differentiate the behaviour of native and model membranes and may indicate an intimate coupling between cellular lipidomes and glycomes.

  19. Dense Pellicular Agarose-Glass Beads for Expanded Bed Application: Flow Hydrodynamics and Solid Phase Classifications

    Institute of Scientific and Technical Information of China (English)

    周鑫; 史清洪; 白姝; 孙彦

    2004-01-01

    Two dense pellicular agarose-glass matrices of different sizes and densities, i.e., AG-S and AG-L, have been characterized for their bed expansion behavior, flow hydrodynamics and particle classifications in an expanded bed system. A 26 mm ID column with side ports was used for sampling the liquid-solid suspension during expanded bed operations. Measurements of the collected solid phase at different column positions yielded the particle size and density distribution data. It was found that the composite matrices showed particle size as well as density classifications along the column axis, i.e., both the size and density of each matrix decreased with increasing the axial bed height. Their axial classifications were expressed by a correlation related to both the particle size and density as a function of the dimensionless axial bed height. The correlation was found to fairly describe the solid phase classifications in the expanded bed system. Moreover, it can also be applied to other two commercial solid matrices designed for expanded bed applications.

  20. Characterization of Pores in Dense Nanopapers and Nanofibrillated Cellulose Membranes: A Critical Assessment of Established Methods.

    Science.gov (United States)

    Orsolini, Paola; Michen, Benjamin; Huch, Anja; Tingaut, Philippe; Caseri, Walter R; Zimmermann, Tanja

    2015-11-25

    Nanofibrillated cellulose (NFC) is a natural fibrous material that can be readily processed into membranes. NFC membranes for fluid separation work in aqueous medium, thus in their swollen state. The present study is devoted to a critical investigation of porosity, pore volume, specific surface area, and pore size distribution of dry and wet NFC nanopapers, also known as membranes, with various established techniques, such as electron microscopy, helium pycnometry, mercury intrusion, gas adsorption (N2 and Kr), and thermoporometry. Although these techniques can be successfully applied to inorganic materials (e.g., mesoporous silica), it is necessary to appraise them for organic and hydrophilic products such as NFC membranes. This is due to different phenomena occurring at the materials interfaces with the probing fluids. Mercury intrusion and gas adsorption are often used for the characterization of porosity-related properties; nevertheless, both techniques characterize materials in the dry state. In parallel, thermoporometry was employed to monitor the structure changes upon swelling, and a water permeance test was run to show the accessibility of the membranes to fluids. For the first time, the methods were systematically screened, and we highlighted the need of uniform sample treatments prior to the measurements (i.e., sample cutting and outgassing protocols) in order to harmonize results from the literature. The need for revising the applicability range of mercury intrusion and the inappropriateness of nitrogen adsorption were pointed out. We finally present a table for selecting the most appropriate method to determine a desired property and propose guidelines for results interpretation from which future users could profit.

  1. Importance of the hexagonal lipid phase in biological membrane organisation

    Directory of Open Access Journals (Sweden)

    Juliette eJouhet

    2013-12-01

    Full Text Available Abstract:Domains are present in every natural membrane. They are characterised by a distinctive protein and/or lipid composition. Their size is highly variable from the nano- to the micrometer scale. The domains confer specific properties to the membrane leading to original structure and function. The determinants leading to domain organisation are therefore important but remain obscure. This review presents how the ability of lipids to organize into hexagonal II or lamellar phases can promote particular local structures within membranes. Since biological membranes are composed of a mixture of lipids, each with distinctive biophysical properties, lateral and transversal sorting of lipids can promote creation of domains inside the membrane through local modulation of the lipid phase. Lipid biophysical properties have been characterized for long based on in vitro analyses using non-natural lipid molecules; their re-examinations using natural lipids might open interesting perspectives on membrane architecture occurring in vivo in various cellular and physiological contexts.

  2. Numerical simulation of dense particle-gas two-phase flow using the minimal potential energy principle

    Institute of Scientific and Technical Information of China (English)

    Xiangjun Liu; Xuchang Xu; Wurong Zhang

    2006-01-01

    A simulation method of dense particle-gas two-phase flow has been developed. The binding force is introduced to present the impact of particle clustering and its expression is deduced according to the principle of minimal potential energy. The cluster collision,break-up and coalescence models are proposed based on the assumption that the particle cluster are treated as one discrete phase. These models are used to numerically study the two-phase flow field in a circulating fluidized bed (CFB). Detailed results of the cluster structure, cluster size, particle volume fraction, gas velocity, and particle velocity are obtained. The correlation between the simulation results and experimental data justifies that these models and algorithm are reasonable, and can be used to efficiently study the dense particle-gas two-phase flow.

  3. DRAG FORCE IN DENSE GAS-PARTICLE TWO-PHASE FLOW

    Institute of Scientific and Technical Information of China (English)

    由长福; 祁海鹰; 徐旭常

    2003-01-01

    Numerical simulations of flow over a stationary particle in a dense gas-particle two-phase flow have been carried out for small Reynolds numbers (less than 100).In order to study the influence of the particles interaction on the drag force,three particle arrangements have been tested:a single particle,two particles placed in the flow direction and many particles located regularly in the flow field.The Navier-Stokes equations are discretized in the three-dimensional space using finite volume method.For the first and second cases,the numerical results agree reasonably well with the data in literature.For the third case,i.e.,the multiparticle case,the influence of the particle volume fraction and Reynolds numbers on the drag force has been investigated.The results show that the computational values of the drag ratio agree approximately with the published results at higher Reynolds numbers (from 34.2 to 68.4),but there is a large difference between them at small Reynolds numbers.

  4. DRAG FORCE IN DENSE GAS—PARTICLE TWO—PHASE FLOW

    Institute of Scientific and Technical Information of China (English)

    由长福; 祁海鹰; 徐旭常

    2003-01-01

    Numerical simulations of flow over a stationary particle in a dense gas-particle two-phase flow have been carried out for small Reynolds numbers (leas than 100). In order to study theinfluence of the particles interaction on the drag force, three particle arrangements have been tested: asingle particle, two particles placed in the flow direction and many particles located regularly in the flowfield. The Navier-Stokes equations are discretized in the three-dimensional space using finite volumemethod. For the first and second cases, the numerical results agree reasonably well with the data inliterature. For the third case, i.e., the multiparticle case, the influence of the particle volume fractionand Reynolds numbers on the drag force has been investigated. The results show that the computationalvalues of the drag ratio agree approximately with the published results at higher Reynolds numbers(from 34.2 to 68.4), but there is a large difference between them at small Reynolds numbers.

  5. Comparison of bioaugmentation and biostimulation for the enhancement of dense nonaqueous phase liquid source zone bioremediation.

    Science.gov (United States)

    Da Silva, M L B; Daprato, R C; Gomez, D E; Hughes, J B; Ward, C H; Alvarez, P J J

    2006-12-01

    Two 11.7-m(3) experimental controlled release systems (ECRS), packed with sandy model aquifer material and amended with tetrachloroethene (PCE) dense nonaqueous phase liquid (DNAPL) source zone, were operated in parallel with identical flow regimes and electron donor amendments. Hydrogen Releasing Compound (Regenesis Bioremediation Products, Inc., San Clemente, California), and later dissolved lactate, served as electron donors to promote dechlorination. One ECRS was bioaugmented with an anaerobic dechlorinating consortium directly into the source zone, and the other served as a control (biostimulated only) to determine the benefits of bioaugmentation. The presence of halorespiring bacteria in the aquifer matrix before bioaugmentation, shown by nested polymerase chain reaction with phylogenetic primers, suggests that dechlorinating catabolic potential may be somewhat widespread. Results obtained corroborate that source zone reductive dechlorination of PCE is possible at near field scale and that a system bioaugmented with a competent halorespiring consortium can enhance DNAPL dissolution and dechlorination processes at significantly greater rates than in a system that is biostimulated only.

  6. Investigation of influence of coal properties on dense-phase pneumatic conveying at high pressure

    Institute of Scientific and Technical Information of China (English)

    Cai Liang; Xiaoxu Xie; Pan Xu; Xiaoping Chen; Changsui Zhao; Xin Wu

    2012-01-01

    Experiments of dense-phase pneumatic conveying of pulverized coal using nitrogen were carried out in a test facility at pressures of up to 3.7 MPa to study the effects of coal type,particle size and moisture content on flow characteristics.The Jenike shear test and scanning electron microscopy (SEM) were employed to provide a better understanding of effects of the material properties on flow characteristics.Two kinds of pulverized coals,Yanzhou and Datong,with similar particle size,moisture content and density,were used in the test.Pressure drop increases with increasing the particle size at similar solid-gas ratio,superficial velocity and pressure in the receiving hopper,and pressure drops through different test sections decrease firstly and then rise with increasing the conveying velocity for the same particle size,mass flow rate and pressure in the receiving hopper.The flowability of pulverized coal decreases with increasing the moisture content in the range from 3.24% to 8.18%.Unconfined yield strength (UYS) increases and flow function (FF) decreases with increasing the moisture content.Results of the shearing tests are consistent with the results of the conveying study.Pressure drops through different test sections are discussed and analyzed.

  7. Textural evolution and phase transformation in titania membranes: Part 2. - Supported membranes

    NARCIS (Netherlands)

    Kumar, Krishnankutty-Nair P.; Keizer, Klaas; Burggraaf, Anthonie J.; Okubo, Tatsuya; Nagamoto, Hidetoshi

    1993-01-01

    Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more

  8. Phase state dependent current fluctuations in pure lipid membranes

    CERN Document Server

    Wunderlich, B; Idzko, A-L; Keyser, U F; Wixforth, A; Myles, V M; Heimburg, T; Schneider, M F

    2009-01-01

    Current fluctuations in pure lipid membranes have been shown to occur under the influence of transmembrane electric fields (electroporation) as well as a result from structural rearrangements of the lipid bilayer during phase transition (soft perforation). We demonstrate that the ion permeability during lipid phase transition exhibits the same qualitative temperature dependence as the macroscopic heat capacity of a D15PC/DOPC vesicle suspension. Microscopic current fluctuations show distinct characteristics for each individual phase state. While current fluctuations in the fluid phase show spike-like behaviour of short time scales (~ 2ms) with a narrow amplitude distribution, the current fluctuations during lipid phase transition appear in distinct steps with time scales in the order of ~ 20ms. 1 We propose a theoretical explanation for the origin of time scales and permeability based on a linear relationship between lipid membrane susceptibilities and relaxation times in the vicinity of the phase transition.

  9. Lipidic cubic phase injector facilitates membrane protein serial femtosecond crystallography.

    Science.gov (United States)

    Weierstall, Uwe; James, Daniel; Wang, Chong; White, Thomas A; Wang, Dingjie; Liu, Wei; Spence, John C H; Bruce Doak, R; Nelson, Garrett; Fromme, Petra; Fromme, Raimund; Grotjohann, Ingo; Kupitz, Christopher; Zatsepin, Nadia A; Liu, Haiguang; Basu, Shibom; Wacker, Daniel; Han, Gye Won; Katritch, Vsevolod; Boutet, Sébastien; Messerschmidt, Marc; Williams, Garth J; Koglin, Jason E; Marvin Seibert, M; Klinker, Markus; Gati, Cornelius; Shoeman, Robert L; Barty, Anton; Chapman, Henry N; Kirian, Richard A; Beyerlein, Kenneth R; Stevens, Raymond C; Li, Dianfan; Shah, Syed T A; Howe, Nicole; Caffrey, Martin; Cherezov, Vadim

    2014-01-01

    Lipidic cubic phase (LCP) crystallization has proven successful for high-resolution structure determination of challenging membrane proteins. Here we present a technique for extruding gel-like LCP with embedded membrane protein microcrystals, providing a continuously renewed source of material for serial femtosecond crystallography. Data collected from sub-10-μm-sized crystals produced with less than 0.5 mg of purified protein yield structural insights regarding cyclopamine binding to the Smoothened receptor.

  10. A density functional theory study of hydrogen occupation in VNiTi alloys used for dense metal membranes

    Energy Technology Data Exchange (ETDEWEB)

    Evtimova, Jenny, E-mail: j.evtimova@itm.cnr.it [Institute on Membrane Technology (CNR-ITM), Italian National Research Council, Rende, CS 87030 (Italy); Department of Environmental and Chemical Engineering (DIATIC), University of Calabria, Rende, CS 87030 (Italy); Drioli, Enrico; De Luca, Giorgio [Institute on Membrane Technology (CNR-ITM), Italian National Research Council, Rende, CS 87030 (Italy)

    2016-04-25

    Attempting to further the development of non-noble dense metal membranes for H{sub 2} separation we conduct a density functional theory study of hydrogen occupancy in V-based alloys with Ni and Ti substitutional solutes. Clusters consisting of 19 quasi-randomly coordinated metal atoms are built to model body-centred cubic VNi and VNiTi alloys with different stoichiometry. The total energy of the target systems is calculated using spatially localised functions. The disposition of a pair of hydrogen atoms within the metal lattice is explored and the binding energy in both tetrahedral and octahedral interstices is evaluated. Large spatial distance between absorbed H atoms is favoured for each of the interstitial sites, rejecting the idea of H clustering in the investigated solid solutions. Moreover, simultaneous occupation of both tetrahedral and octahedral interstices is found to be energetically feasible despite the common believe for solely tetrahedral occupancy in metals with body-centred cubic structure. Nonetheless, the most favourable absorption site depends on the solute concentration in the V-based alloys. Calculations of the binding energy using cluster models with different metal atomic ratio provide information on the hydrogen absorption affinity as a function of alloy composition. Enhancement of the absorption affinity with added Ti until certain limit is found, while Ni solutes influence this property in the opposite direction. The applied methodology can be used further in high-throughput calculations to screen various metal alloys for hydrogen separation membranes. - Highlights: • Large distance between H atoms in VNiTi is favoured for sites of the same symmetry. • Simultaneous occupation of T and O sites in VNiTi alloys is energetically feasible. • Variation of alloy composition influences the site preference for H occupation. • Increase of the Ti:Ni ratio by V = const increases the hydrogen absorption affinity.

  11. Tension induced phase transitions in biomimetic fluid membranes

    Science.gov (United States)

    Shapiro, Marc; Vlahovska, Petia

    2012-11-01

    Membranes in eukaryotic cells are mixtures of hundreds of lipid species. The lipid diversity enables membranes to phase separate and form domains, called rafts, which play a critical role in cell functions such as signaling and trafficking. The phase transitions underlying raft formation have been extensively studied as a function of temperature and composition. However, the third dimension of the phase diagram, i.e., the tension (2D pressure), is still unexplored because membrane tension is difficult to control and quantify. To overcome this challenge, we develop two approaches, capillary micromechanics and electrodeformation, in which the tension is regulated by the area dilation accompanying deformation of a vesicle (a closed membrane). The first technique consists of forcing an initially quasi-spherical vesicle through a tapered glass microcapillary, while the second method utilizes uniform electric fields to deform the vesicle into an ellipsoid. Domains are visualized using a fluorescent dye, which preferentially partitions in one of the phases. The experimental results suggest that the miscibility temperature (at which domains form in an initially homogeneous membrane) increases with applied tension. Domain motions and coarsening are also investigated.

  12. Phase behaviors and membrane properties of model liposomes: Temperature effect

    Science.gov (United States)

    Wu, Hsing-Lun; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-09-01

    The phase behaviors and membrane properties of small unilamellar vesicles have been explored at different temperatures by dissipative particle dynamics simulations. The vesicles spontaneously formed by model lipids exhibit pre-transition from gel to ripple phase and main transition from ripple to liquid phase. The vesicle shape exhibits the faceted feature at low temperature, becomes more sphere-like with increasing temperature, but loses its sphericity at high temperature. As the temperature rises, the vesicle size grows but the membrane thickness declines. The main transition (Tm) can be identified by the inflection point. The membrane structural characteristics are analyzed. The inner and outer leaflets are asymmetric. The length of the lipid tail and area density of the lipid head in both leaflets decrease with increasing temperature. However, the mean lipid volume grows at low temperature but declines at high temperature. The membrane mechanical properties are also investigated. The water permeability grows exponentially with increasing T but the membrane tension peaks at Tm. Both the bending and stretching moduli have their minima near Tm. Those results are consistent with the experimental observations, indicating that the main signatures associated with phase transition are clearly observed in small unilamellar vesicles.

  13. Validation of a model of gas and dense phase CO jet releases for carbon capture and storage application

    OpenAIRE

    Wareing, CJ; Fairweather, M; Woolley, RM; Falle, SAEG

    2014-01-01

    Carbon capture and storage (CCS) presents a short-term option for significantly reducing the amount of carbon dioxide (CO) released into the atmosphere and mitigating the effects of climate change. To this end, National Grid initiated a programme of research known as the COOLTRANS research programme. Part of this work involves the development of a mathematical model for predicting the near-field dispersion of CO following the puncture or rupture of a high pressure dense phase pipeline typical...

  14. Modelling ruptures of buried high pressure dense phase CO2 pipelines in carbon capture and storage applications - Part I. Validation

    OpenAIRE

    Wareing, CJ; Fairweather, M.; Falle, SAEG; Woolley, RM

    2015-01-01

    Carbon dioxide (CO2) capture and storage presents a short-term option for significantly reducing the amount of CO2 released into the atmosphere and mitigating the effects of climate change. To this end, National Grid initiated the COOLTRANS research programme to consider the pipeline transportation of high pressure dense phase CO2, including the development and application of a mathematical model for predicting the sonic near-field dispersion of pure CO2 following the venting or failure of su...

  15. Characterization of the gas pulse frequency, amplitude and velocity in non-steady dense phase pneumatic conveying of powders

    Institute of Scientific and Technical Information of China (English)

    Kenneth C.Williams; Mark G.Jones; Ahmed A.Cenna

    2008-01-01

    Current modelling techniques for the prediction of conveying line pressure drop in low velocity dense phase pneumatic conveying are largely based on steady state analyses.Work in this area has been on-going for many years with only marginal improvements in the accuracy of prediction being achieved.Experimental and theoretical investigations undertaken by the authors suggest that the flow mechanisms involved in dense phase conveying are dominated by transient effects rather than those of steady state and are possibly the principal reasons for the limited improvement in accuracy.This paper reports on investigations on the pressure fluctuation behaviour in dense phase pneumatic conveying of powders.The pressure behaviour of the gas flow in the top section of the pipeline was found to exhibit pulsatile oscillations.In particular,the pulse velocity showed variation in magnitude while the frequency of the oscillations rarely exceeded 5 Hz.A wavelet analysis using the Daubechie 4 wavelet found that the amplitude of the oscillations increased along the pipeline.Furthermore,there was significant variation in gas pulse amplitude for different types of particulate material.

  16. Hydrogen Permeation Properties of Perovskite-type BaCe0.9Mn0.1O3-δDense Ceramic Membrane

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The electrical conduction properties of dense BaCe0.9Mn0.1O3-δ (BCM10) membrane were investigated in the temperature range of 600-900℃. High ionic and electronic conductivities at elevated temperatures make BCM10 a potential ceramic material for hydrogen separation. Hydrogen permeation through BCM10 membranes was studied using a hightemperature permeation cell. Little hydrogen could be detected at the sweep side. However,appreciable hydrogen can permeate through BCM10 membrane coated with porous platinum black,which shows that the process of hydrogen permeation through BCM10 membranes was controlled by the catalytic decomposition and recomposition of hydrogen on the surfaces of BCM10 membranes.

  17. Inverse lyotropic phases of lipids and membrane curvature

    Energy Technology Data Exchange (ETDEWEB)

    Shearman, G C; Ces, O; Templer, R H; Seddon, J M [Department of Chemistry, Imperial College London, SW7 2AZ (United Kingdom)

    2006-07-19

    In recent years it has become evident that many biological functions and processes are associated with the adoption by cellular membranes of complex geometries, at least locally. In this paper, we initially discuss the range of self-assembled structures that lipids, the building blocks of biological membranes, may form, focusing specifically on the inverse lyotropic phases of negative interfacial mean curvature. We describe the roles of curvature elasticity and packing frustration in controlling the stability of these inverse phases, and the experimental determination of the spontaneous curvature and the curvature elastic parameters. We discuss how the lyotropic phase behaviour can be tuned by the addition of compounds such as long-chain alkanes, which can relieve packing frustration. The latter section of the paper elaborates further on the structure, geometric properties, and stability of the inverse bicontinuous cubic phases.

  18. Aqueous phase deposition of dense tin oxide films with nano-structured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Yoshitake, E-mail: masuda-y@aist.go.jp; Ohji, Tatsuki; Kato, Kazumi

    2014-06-01

    Dense tin oxide films were successfully fabricated in an aqueous solution. The pH of the solutions was controlled to pH 1.3 by addition of HCl. Precise control of solution condition and crystal growth allowed us to obtain dense tin oxide films. Concave–convex surface of fluorine-doped tin oxide (FTO) substrates was entirely-covered with the continuous films. The films were about 65 nm in thickness and had nano-structured surfaces. Morphology of the films was strikingly different from our previous reported nano-sheet assembled structures. The films were not removed from the substrates by strong water flow or air blow to show strong adhesion strength. The aqueous solution process can be applied to surface coating of various materials such as nano/micro-structured surfaces, particles, fibers, polymers, metals or biomaterials. - Graphical abstract: Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. They had nano-structured surfaces. Concave-convex substrates were entirely-covered with the continuous films. - Highlights: • Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. • They had nano-structured surfaces. • Concave–convex substrates were entirely-covered with the continuous films.

  19. Composite Membrane Formation by Combination of Reaction-Induced and Nonsolvent-Induced Phase Separation

    KAUST Repository

    Aburabie, Jamaliah

    2017-05-25

    A novel method of preparing skinned asymmetric membranes with two distinctive layers is described: a top layer composed of chemically cross-linked polymer chains (dense layer) and a bottom layer of non-cross-linked polymer chains (porous substructure). The method consists of two simple steps that are compatible with industrial membrane fabrication facilities. Unlike conventional processes to prepare asymmetric membranes, with this approach it is possible to finely control the structure and functionalities of the final membrane. The thickness of the dense layer can be easily controlled over several orders of magnitude and targeted functional groups can be readily incorporated in it.

  20. Low-temperature phases of dense hydrogen and deuterium by first-principles path-integral molecular dynamics

    Science.gov (United States)

    Torrent, Marc; Geneste, Gregory

    2012-02-01

    The low-temperature phases of dense hydrogen and deuterium have been investigated using first-principles path-integral molecular dynamics, a technique that we have recently implemented in the ABINIT code and that allows to account for the quantum fluctuations of atomic nuclei. A massively parallelized scheme is applied to produce trajectories of several tens of thousands steps using a 64-atom supercell and a Trotter number of 64. The so-called phases I, II and III are studied and compared to the structures proposed in the literature. The quantum fluctuations produce configurational disorder and are shown to systematically enhance the symmetry of the system: a continuous gain of symmetry in the angular density of probability of the molecules is found from classical particles to quantum D2 and finally to quantum H2. Particular emphasis is made on the ``broken-symmetry'' phase (phase II).

  1. Large-Aperture Membrane Active Phased-Array Antennas

    Science.gov (United States)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  2. Photostability of gas- and solid-phase biomolecules within dense molecular clouds due to soft X-rays

    CERN Document Server

    Pilling, S; Nascimento, E M do; Marinho, R R T; Boechat-Roberty, H M; de Coutinho, L H; de Souza, G G B; de Castilho, R B; Cavasso-Filho, R L; Lago, A F; de Brito, A N

    2010-01-01

    An experimental photochemistry study involving gas- and solid-phase amino acids (glycine, DL-valine, DL-proline) and nucleobases (adenine and uracil) under soft X-rays was performed. The aim was to test the molecular stabilities of essential biomolecules against ionizing photon fields inside dense molecular clouds and protostellar disks analogs. In these environments, the main energy sources are the cosmic rays and soft X-rays. The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), employing 150 eV photons. In-situ sample analysis was performed by Time-of-flight mass spectrometer (TOF-MS) and Fourier transform infrared (FTIR) spectrometer, for gas- and solid- phase analysis, respectively. The half-life of solid phase amino acids, assumed to be present at grain mantles, is at least 3E5 years and 3E8 years inside dense molecular clouds and protoplanetary disks, respectively. We estimate that for gas-phase compounds these values increase one order of magnitude since the dissociation cr...

  3. Textural evolution and phase transformation in titania membranes: Part 1. -unsupported membranes

    NARCIS (Netherlands)

    Kumar, Krishnankutty-Nair P.; Keizer, Klaas; Burggraaf, Anthonie J.

    1993-01-01

    Textural evolution in sol–gel derived nanostructured unsupported titania membranes has been studied using differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermal gravimetry (TG), X-ray diffraction (XRD) and N2 adsorption. The anatase-to-rutile phase transformation kinet

  4. Molecular and atomic line surveys of galaxies I: the dense, star-forming phase as a beacon

    CERN Document Server

    Geach, James E

    2012-01-01

    We predict the space density of molecular gas reservoirs in the Universe, and place a lower limit on the number counts of carbon monoxide (CO), hydrogen cyanide (HCN) molecular and [CII] atomic emission lines in blind redshift surveys in the submillimeter-centimeter spectral regime. Our model uses: (a) recently available HCN Spectral Line Energy Distributions (SLEDs) of local Luminous Infrared Galaxies (LIRGs, L_IR>10^11 L_sun), (b) a value for epsilon=SFR/M_dense(H_2) provided by new developments in the study of star formation feedback on the interstellar medium and (c) a model for the evolution of the infrared luminosity density. Minimal 'emergent' CO SLEDs from the dense gas reservoirs expected in all star-forming systems in the Universe are then computed from the HCN SLEDs since warm, HCN-bright gas will necessarily be CO-bright, with the dense star-forming gas phase setting an obvious minimum to the total molecular gas mass of any star-forming galaxy. We include [CII] as the most important of the far-inf...

  5. Phase transition temperatures of 405-725 K in superfluid ultra-dense hydrogen clusters on metal surfaces

    Science.gov (United States)

    Holmlid, Leif; Kotzias, Bernhard

    2016-04-01

    Ultra-dense hydrogen H(0) with its typical H-H bond distance of 2.3 pm is superfluid at room temperature as expected for quantum fluids. It also shows a Meissner effect at room temperature, which indicates that a transition point to a non-superfluid state should exist above room temperature. This transition point is given by a disappearance of the superfluid long-chain clusters H2N(0). This transition point is now measured for several metal carrier surfaces at 405 - 725 K, using both ultra-dense protium p(0) and deuterium D(0). Clusters of ordinary Rydberg matter H(l) as well as small symmetric clusters H4(0) and H3(0) (which do not give a superfluid or superconductive phase) all still exist on the surface at high temperature. This shows directly that desorption or diffusion processes do not remove the long superfluid H2N(0) clusters. The two ultra-dense forms p(0) and D(0) have different transition temperatures under otherwise identical conditions. The transition point for p(0) is higher in temperature, which is unexpected.

  6. Catalytically active telomerase holoenzyme is assembled in the dense fibrillar component of the nucleolus during S phase.

    Science.gov (United States)

    Lee, Ji Hoon; Lee, Yang Sin; Jeong, Sun Ah; Khadka, Prabhat; Roth, Jürgen; Chung, In Kwon

    2014-02-01

    The maintenance of human telomeres requires the ribonucleoprotein enzyme telomerase, which is composed of telomerase reverse transcriptase (TERT), telomerase RNA component, and several additional proteins for assembly and activity. Telomere elongation by telomerase in human cancer cells involves multiple steps including telomerase RNA biogenesis, holoenzyme assembly, intranuclear trafficking, and telomerase recruitment to telomeres. Although telomerase has been shown to accumulate in Cajal bodies for association with telomeric chromatin, it is unclear where and how the assembly and trafficking of catalytically active telomerase is regulated in the context of nuclear architecture. Here, we show that the catalytically active holoenzyme is initially assembled in the dense fibrillar component of the nucleolus during S phase. The telomerase RNP is retained in nucleoli through the interaction of hTERT with nucleolin, a major nucleolar phosphoprotein. Upon association with TCAB1 in S phase, the telomerase RNP is transported from nucleoli to Cajal bodies, suggesting that TCAB1 acts as an S-phase-specific holoenzyme component. Furthermore, depletion of TCAB1 caused an increase in the amount of telomerase RNP associated with nucleolin. These results suggest that the TCAB1-dependent trafficking of telomerase to Cajal bodies occurs in a step separate from the holoenzyme assembly in nucleoli. Thus, we propose that the dense fibrillar component is the provider of active telomerase RNP for supporting the continued proliferation of cancer and stem cells.

  7. Numerical investigation of influence on heat transfer characteristics to pneumatically conveyed dense phase flow by selecting models and boundary conditions

    Science.gov (United States)

    Zheng, Y.; Liu, Q.; Li, Y.

    2012-03-01

    Solids moving with a gas stream in a pipeline can be found in many industrial processes, such as power generation, chemical, pharmaceutical, food and commodity transfer processes. A mass flow rate of the solids is important characteristic that is often required to be measured (and controlled) to achieve efficient utilization of energy and raw materials in pneumatic conveying systems. The methods of measuring the mass flow rate of solids in a pneumatic pipeline can be divided into direct and indirect (inferential) measurements. A thermal solids' mass flow-meter, in principle, should ideally provide a direct measurement of solids flow rate, regardless of inhomogeneities in solids' distribution and environmental impacts. One key issue in developing a thermal solids' mass flow-meter is to characterize the heat transfer between the hot pipe wall and the gas-solids dense phase flow. The Eulerian continuum modeling with gas-solid two phases is the most common method for pneumatic transport. To model a gas-solid dense phase flow passing through a heated region, the gas phase is described as a continuous phase and the particles as the second phase. This study aims to describe the heat transfer characteristics between the hot wall and the gas-solids dense phase flow in pneumatic pipelines by modeling a turbulence gas-solid plug passing through the heated region which involves several actual and crucial issues: selections of interphase exchange coefficient, near-wall region functions and different wall surface temperatures. A sensitivity analysis was discussed to identify the influence on the heat transfer characteristics by selecting different interphase exchange coefficient models and different boundary conditions. Simulation results suggest that sensitivity analysis in the choice of models is very significant. The simulation results appear to show that a combination of choosing the Syamlal-O'Brien interphase exchange coefficient model and the standard k-ɛ model along with

  8. Effects of Dense Phase-CO2 Treatments on Microflora, Enzymes and Browning of Chinese Winter Jujube Juice

    Directory of Open Access Journals (Sweden)

    Wei Zong

    2015-03-01

    Full Text Available Chinese winter jujube juice was treated with Dense Phase Carbon Dioxide (DPCD to inactivate microorganisms, Polyphenoloxidase (PPO activity, Peroxidase (POD activity and control browing. The effect of varying pressures (5 to 30 MPa and different treatment time (0 to 50 min on the amount of natural microorganisms, PPO activity, POD activity and browning degree were measured. After experiment, the inactivation of natural microorganisms, PPO activity and POD activity exposed to DPCD were significantly increased with increasing pressure. Treated jujube juice had lower browning degree than untreated jujube juice. The experimental results showed that the DPCD treatment can be regarded as a good pretreatment means for winter jujube juice processing.

  9. Dual Phase Membrane for High Temperature CO2 Separation

    Energy Technology Data Exchange (ETDEWEB)

    Jerry Lin

    2007-06-30

    This project aimed at synthesis of a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Metal-carbonate dual-phase membranes were prepared by the direct infiltration method and the synthesis conditions were optimized. Permeation tests for CO{sub 2} and N{sub 2} from 450-750 C showed very low permeances of those two gases through the dual-phase membrane, which was expected due to the lack of ionization of those two particular gases. Permeance of the CO{sub 2} and O{sub 2} mixture was much higher, indicating that the gases do form an ionic species, CO{sub 3}{sup 2-}, enhancing transport through the membrane. However, at temperatures in excess of 650 C, the permeance of CO{sub 3}{sup 2-} decreased rapidly, while predictions showed that permeance should have continued to increase with temperature. XRD data obtained from used membrane indicated that lithium iron oxides formed on the support surface. This lithium iron oxide layer has a very low conductivity, which drastically reduces the flow of electrons to the CO{sub 2}/O{sub 2} gas mixture; thus limiting the formation of the ionic species required for transport through the membrane. These results indicated that the use of stainless steel supports in a high temperature oxidative environment can lead to decreased performance of the membranes. This revelation created the need for an oxidation resistant support, which could be gained by the use of a ceramic-type membrane. Work was extended to synthesize a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Helium permeance of the support before and after infiltration of molten carbonate are on the order of 10{sup -6} and 10{sup -10} moles/m{sup 2} {center_dot} Pa {center_dot} s respectively, indicating that the molten carbonate is able to sufficiently infiltrate the membrane. It was found that La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (LSCF) was a suitable candidate for the support

  10. Near-critical fluctuations and cytoskeleton-assisted phase separation lead to subdiffusion in cell membranes

    CERN Document Server

    Ehrig, Jens; Schwille, Petra

    2010-01-01

    We address the relationship between membrane microheterogeneity and anomalous subdiffusion in cell membranes by carrying out Monte Carlo simulations of two-component lipid membranes. We find that near-critical fluctuations in the membrane lead to transient subdiffusion, while membrane-cytoskeleton interaction strongly affects phase separation, enhances subdiffusion, and eventually leads to hop diffusion of lipids. Thus, we present a minimum realistic model for membrane rafts showing the features of both microscopic phase separation and subdiffusion.

  11. Oxygen permeation in thin, dense Ce0.9Gd0.1O 1.95- membranes II. experimental determination

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Søgaard, Martin; Glasscock, Julie

    2011-01-01

    Thin (∼30 m), dense Ce0.9Gd0.1O1.95- (CGO10) membranes (5 5 cm2+) supported on a porous NiO/YSZ substrate were fabricated by tape casting, wet powder spraying and lamination. A La 0.58Sr0.4Co0.2Fe0.8O 3-δ/Ce0.9Gd0.1O1.95- (LSCF/CGO10) composite cathode was applied by screen printing. Oxygen...... compartment. The performance of the membrane was also investigated under varying CH 4 and H2O gas mixtures at 1106 K. The oxygen flux increased with decreasing steam to carbon ratio and was found to exceed 10 N mL min-1 cm-2 of O2 for steam to carbon ratios below 4:3. Post-test analysis of the tested membrane...

  12. Fast creation of dense MgB2 phase in wires made by IMD process

    Science.gov (United States)

    Kováč, P.; Hušek, I.; Melišek, T.; Kopera, L.; Kulich, M.

    2016-10-01

    Single-core MgB2 wires have been made by internal magnesium diffusion (IMD) into boron process. Heat treatments were performed at variable periods (4-90 min) for two adjusted temperatures 635 °C and 650 °C, with an overshoot of ≈20 °C after 5 min. Critical currents of differently treated MgB2/Ti/GlidCop wires have been measured and related with the MgB2 layers. The fast creation MgB2 compound has been observed after 8 min annealing at both temperatures and showing the critical current maxima. The less uniform MgB2 containing cracks was created for longer annealing periods (≥10 min), which resulted in lowered critical currents and worsened thermal stability. The fast creation of dense MgB2 allows it to utilize a continual and short heat treatment process for high current density wires made by IMD.

  13. Measuring dynamic membrane fluctuations in cell membrane using quantitative phase imaging (Conference Presentation)

    Science.gov (United States)

    Lee, SangYun; Kim, Kyoohyun; Park, YongKeun

    2017-02-01

    There is a strong correlation between the dynamic membrane fluctuations and the biomechanical properties of living cells. The dynamic membrane fluctuation consists of submicron displacements, and can be altered by changing the cells' pathophysiological conditions. These results have significant relevance to the understanding of RBC biophysics and pathology, as follows. RBCs must withstand large mechanical deformations during repeated passages through the microvasculature and the fenestrated walls of the splenic sinusoids. This essential ability is diminished with senescence, resulting in physiological destruction of the aging RBCs. Pathological destruction of the red cells, however, occurs in cells affected by a host of diseases such as spherocytosis, malaria, and Sickle cell disease, as RBCs depart from their normal discoid shape and lose their deformability. Therefore, quantifying the RBC deformability insight into a variety of problems regarding the interplay of cell structure, dynamics, and function. Furthermore, the ability to monitor mechanical properties of RBCs is of vital interest in monitoring disease progression or response to treatment as molecular and pharmaceutical approaches for treatment of chronic diseases. Here, we present the measurements of dynamic membrane fluctuations in live cells using quantitative phase imaging techniques. Measuring both the 3-D refractive index maps and the dynamic phase images of live cells are simultaneously measured, from which dynamic membrane fluctuation and deformability of cells are precisely calculated. We also present its applications to various diseases ranging from sickle cell diseases, babesiosis, and to diabetes.

  14. High-pressure synchrotron x-ray diffraction and infrared microspectroscopy: applications to dense hydrous phases

    CERN Document Server

    Liu, Z; Yang, H; Mao Ho Kwang; Hemley, R J

    2002-01-01

    Synchrotron x-ray diffraction (XRD) and infrared (IR) absorption spectra of hydrous and 'anhydrous' forms of phase X were measured to 30 GPa at room temperature. Three OH stretching modes were found in the hydrous phase, and surprisingly one sharp OH mode was observed in the previously characterized anhydrous phase. All OH stretching modes soften and broaden with increasing pressure and become very weak above approx 20 GPa. XRD indicates that the crystal structure remains stable up to 30 GPa. Combining IR absorption and XRD results, the behaviour is attributed to pressure-induced distortion of the Si sub 2 O sub 7 groups and disorder of the hydrogen atoms. The bulk moduli of the hydrous and 'anhydrous' phases are in the region of 74 GPa.

  15. Isotope effects in dense solid hydrogen - Phase transition in deuterium at 190 + or - 20 GPa

    Science.gov (United States)

    Hemley, R. J.; Mao, H. K.

    1989-01-01

    Raman measurements of solid normal deuterium compressed in a diamond-anvil cell indicate that the material undergoes a structural phase transformation at 190 + or - 20 GPa and 77 K. Spectroscopically, the transition appears analogous to that observed in hydrogen at 145 + or - 5 GPa. The large isotope effect on the transition pressure suggests there is a significant vibrational contribution to the relative stability of the solid phases of hydrogen at very high densities.

  16. Alfv\\'en wave phase mixing in flows -- why over-dense solar coronal open magnetic field structures are cool?

    CERN Document Server

    Tsiklauri, D

    2015-01-01

    Our magnetohydrodynamic (MHD) simulations and analytical calculations show that, when a background flow is present, mathematical expressions for the Alfv\\'en wave (AW) damping via phase mixing are modified by a following substitution $C_A^\\prime(x) \\to C_A^\\prime(x)+V_0^\\prime(x)$, where $C_A$ and $V_0$ are AW phase and the flow speeds and prime denotes derivative in the direction across the background magnetic field. In uniform magnetic field and over-dense plasma structures, in which $C_A$ is smaller compared to surrounding plasma, the flow, that is confined to the structure, in the same direction as the AW, reduces the effect of phase mixing, because on the edges of the structure $C_A^\\prime$ and $V_0^\\prime$ have opposite sign. Thus, the wave damps via phase mixing {\\it slower} compared to the case without the flow. This is the consequence of the co-directional flow reducing the wave front stretching in the transverse direction. Although, the result is generic and is applicable to different laboratory or ...

  17. Delicate polydimethylsiloxane hollow fibre membrane interfaces for condensed phase membrane introduction mass spectrometry (CP-MIMS).

    Science.gov (United States)

    Willis, Megan D; Duncan, Kyle D; Krogh, Erik T; Gill, Chris G

    2014-04-15

    On-line analytical techniques such as condensed phase membrane introduction mass spectrometry (CP-MIMS) permit direct and rapid analyte measurements in complex samples. Direct, rapid analytical methods are desirable because they eliminate potential contamination and/or dilution from sample workup steps, facilitate rapid sample screening and allow 'real-time' monitoring applications. PDMS hollow fibre membrane (HFM) flow cell interfaces (215 µm, 35 µm, and 0.5 µm thick composite) were coupled with an electrospray ionization (ESI) triple quadrupole mass spectrometer. A simultaneous push/pull methanol acceptor phase delivery system and membrane mounting via epoxy potting ensured that the delicate membranes were not ruptured during construction or sample measurements. Both flow cell and direct insertion 'J-Probe' interfaces using the 0.5 µm thick composite PDMS HFM were utilized for direct naphthenic acid measurements. Delicate HFM CP-MIMS interfaces were used for the rapid screening and continuous, on-line monitoring of carboxylic acids and hydroxylated compounds directly in complex sample matrices under ambient conditions at pptr - ppb detection limits. Push/pull acceptor phase (methanol) delivery maintained ambient hydrostatic pressures within the HFMs, improving ESI stability and analytical sensitivity, especially with stopped acceptor flow operation. Signal response times less than 2 min were achieved for thin, composite PDMS HFMs at 30°C. The continuous monitoring of naphthenic acid degradation was demonstrated. Delicate PDMS HFM CP-MIMS interfaces were developed and used for the direct, on-line detection of low volatility, polar analytes in complex aqueous samples. Composite PDMS HFM interfaces yielded the best overall analytical performance improvements, and were used to demonstrate the direct measurement of naphthenic acids in complex aqueous samples. Copyright © 2014 John Wiley & Sons, Ltd.

  18. A two-phase solid/fluid model for dense granular flows including dilatancy effects

    Science.gov (United States)

    Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Koné, El-Hadj; Narbona-Reina, Gladys

    2016-04-01

    Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [{Iverson et al.}, 2010]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure [{Bouchut et al.}, 2016]. The model is derived from a 3D two-phase model proposed by {Jackson} [2000] based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work [{Bouchut et al.}, 2015]. In particular, {Pitman and Le} [2005] replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's model by closing the mixture equations by a weak compressibility relation following {Roux and Radjai} [1998]. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To

  19. Theory of complex fluids in the warm-dense-matter regime, and application to phase-transitions in liquid carbon

    CERN Document Server

    Dharma-wardana, M W C

    2016-01-01

    Using data from recent laser-shock experiments and related density-functional molecular-dynamics simulations on carbon, we demonstrate that the ionic structures predicted within the neutral-pseudo-atom approach for a complex liquid in the warm-dense matter regime are in good agreement with available data, even where transient covalent bonding dominates ionic correlations. Evidence for an unusual phase transition of a liquid $\\to$ vapor with an abrupt decrease in ionization occurring simultaneously is presented. Here a covalently-bonded metallic-liquid, i.e., carbon of density 1.0 g/cm$^3$, transits to a disordered mono-atomic fluid at 7 eV. Other transitions where the mean ionization $Z$ drops abruptly are also uncovered

  20. Co-current and counter-current configurations for ethanol steam reforming in a dense Pd–Ag membrane reactor

    NARCIS (Netherlands)

    Gallucci, F.; De Falco, M.; Tosti, S.; Marrelli, L.; Basile, A.

    2008-01-01

    The ethanol steam-reforming reaction to produce pure hydrogen has been studied theoretically. A mathematical model has been formulated for a traditional system and a palladium membrane reactor packed with a Co-based catalyst and the simulation results related to the membrane reactor for both co-curr

  1. Moderate Temperature Dense Phase Hydrogen Storage Materials within the US Department of Energy (DOE H2 Storage Program: Trends toward Future Development

    Directory of Open Access Journals (Sweden)

    Scott McWhorter

    2012-05-01

    Full Text Available Hydrogen has many positive attributes that make it a viable choice to augment the current portfolio of combustion-based fuels, especially when considering reducing pollution and greenhouse gas (GHG emissions. However, conventional methods of storing H2 via high-pressure or liquid H2 do not provide long-term economic solutions for many applications, especially emerging applications such as man-portable or stationary power. Hydrogen storage in materials has the potential to meet the performance and cost demands, however, further developments are needed to address the thermodynamics and kinetics of H2 uptake and release. Therefore, the US Department of Energy (DOE initiated three Centers of Excellence focused on developing H2 storage materials that could meet the stringent performance requirements for on-board vehicular applications. In this review, we have summarized the developments that occurred as a result of the efforts of the Metal Hydride and Chemical Hydrogen Storage Centers of Excellence on materials that bind hydrogen through ionic and covalent linkages and thus could provide moderate temperature, dense phase H2 storage options for a wide range of emerging Proton Exchange Membrane Fuel Cell (PEM FC applications.

  2. Use of a Ceramic Membrane to Improve the Performance of Two-Separate-Phase Biocatalytic Membrane Reactor.

    Science.gov (United States)

    Ranieri, Giuseppe; Mazzei, Rosalinda; Wu, Zhentao; Li, Kang; Giorno, Lidietta

    2016-03-14

    Biocatalytic membrane reactors (BMR) combining reaction and separation within the same unit have many advantages over conventional reactor designs. Ceramic membranes are an attractive alternative to polymeric membranes in membrane biotechnology due to their high chemical, thermal and mechanical resistance. Another important use is their potential application in a biphasic membrane system, where support solvent resistance is highly needed. In this work, the preparation of asymmetric ceramic hollow fibre membranes and their use in a two-separate-phase biocatalytic membrane reactor will be described. The asymmetric ceramic hollow fibre membranes were prepared using a combined phase inversion and sintering technique. The prepared fibres were then used as support for lipase covalent immobilization in order to develop a two-separate-phase biocatalytic membrane reactor. A functionalization method was proposed in order to increase the density of the reactive hydroxyl groups on the surface of ceramic membranes, which were then amino-activated and treated with a crosslinker. The performance and the stability of the immobilized lipase were investigated as a function of the amount of the immobilized biocatalytst. Results showed that it is possible to immobilize lipase on a ceramic membrane without altering its catalytic performance (initial residual specific activity 93%), which remains constant after 6 reaction cycles.

  3. Use of a Ceramic Membrane to Improve the Performance of Two-Separate-Phase Biocatalytic Membrane Reactor

    Directory of Open Access Journals (Sweden)

    Giuseppe Ranieri

    2016-03-01

    Full Text Available Biocatalytic membrane reactors (BMR combining reaction and separation within the same unit have many advantages over conventional reactor designs. Ceramic membranes are an attractive alternative to polymeric membranes in membrane biotechnology due to their high chemical, thermal and mechanical resistance. Another important use is their potential application in a biphasic membrane system, where support solvent resistance is highly needed. In this work, the preparation of asymmetric ceramic hollow fibre membranes and their use in a two-separate-phase biocatalytic membrane reactor will be described. The asymmetric ceramic hollow fibre membranes were prepared using a combined phase inversion and sintering technique. The prepared fibres were then used as support for lipase covalent immobilization in order to develop a two-separate-phase biocatalytic membrane reactor. A functionalization method was proposed in order to increase the density of the reactive hydroxyl groups on the surface of ceramic membranes, which were then amino-activated and treated with a crosslinker. The performance and the stability of the immobilized lipase were investigated as a function of the amount of the immobilized biocatalytst. Results showed that it is possible to immobilize lipase on a ceramic membrane without altering its catalytic performance (initial residual specific activity 93%, which remains constant after 6 reaction cycles.

  4. Phase retrieval deblurring for imaging of dense object within a low scattering soft biological tissue

    Science.gov (United States)

    Shalev, Maya Aviv; Rivenson, Yair; Meiri, Amihai; Zalevsky, Zeev

    2016-09-01

    Tissues are characterized by a strong scattering of visible optical radiation, which prevents one from achieving deep-tissue imaging. We propose a computational imaging technique for the inference of specific macroscopic, spatial phase distribution features of the scattering media. The spatial phase distribution is reconstructed from several defocused intensity images. We empirically demonstrate the method by reconstructing the location of two fibula chicken bones, embedded within chicken breast tissue. The suggested technique is safe, using visible laser illumination, and noninvasive. It is also cost-effective since a simple optical system is used and the images are acquired using a conventional camera, and it does not require interferometric detection as well as direct access to the object in absence of the layer.

  5. Indications for a critical end point in the phase diagram for hot and dense nuclear matter.

    Science.gov (United States)

    Lacey, Roy A

    2015-04-10

    Excitation functions for the Gaussian emission source radii difference (R_{out}^{2}-R_{side}^{2}) obtained from two-pion interferometry measurements in Au+Au (sqrt[s_{NN}]=7.7-200  GeV) and Pb+Pb (sqrt[s_{NN}]=2.76  TeV) collisions are studied for a broad range of collision centralities. The observed nonmonotonic excitation functions validate the finite-size scaling patterns expected for the deconfinement phase transition and the critical end point (CEP), in the temperature versus baryon chemical potential (T,μ_{B}) plane of the nuclear matter phase diagram. A finite-size scaling (FSS) analysis of these data suggests a second order phase transition with the estimates T^{cep}∼165  MeV and μ_{B}^{cep}∼95  MeV for the location of the critical end point. The critical exponents (ν≈0.66 and γ≈1.2) extracted via the same FSS analysis place this CEP in the 3D Ising model universality class.

  6. SURVIVAL OF INTERSTELLAR MOLECULES TO PRESTELLAR DENSE CORE COLLAPSE AND EARLY PHASES OF DISK FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Hincelin, U. [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States); Wakelam, V.; Hersant, F.; Guilloteau, S. [University of Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Commerçon, B., E-mail: ugo.hincelin@virginia.edu [Laboratoire de radioastronomie, LERMA, Observatoire de Paris, Ecole Normale Supérieure (UMR 8112 CNRS), 24 rue Lhomond, F-75231 Paris Cedex 05 (France)

    2013-09-20

    An outstanding question of astrobiology is the link between the chemical composition of planets, comets, and other solar system bodies and the molecules formed in the interstellar medium. Understanding the chemical and physical evolution of the matter leading to the formation of protoplanetary disks is an important step for this. We provide some new clues to this long-standing problem using three-dimensional chemical simulations of the early phases of disk formation: we interfaced the full gas-grain chemical model Nautilus with the radiation-magnetohydrodynamic model RAMSES, for different configurations and intensities of the magnetic field. Our results show that the chemical content (gas and ices) is globally conserved during the collapsing process, from the parent molecular cloud to the young disk surrounding the first Larson core. A qualitative comparison with cometary composition suggests that comets are constituted of different phases, some molecules being direct tracers of interstellar chemistry, while others, including complex molecules, seem to have been formed in disks, where higher densities and temperatures allow for an active grain surface chemistry. The latter phase, and its connection with the formation of the first Larson core, remains to be modeled.

  7. Adhesion-induced phase behavior of two-component membranes and vesicles.

    Science.gov (United States)

    Rouhiparkouhi, Tahereh; Weikl, Thomas R; Discher, Dennis E; Lipowsky, Reinhard

    2013-01-22

    The interplay of adhesion and phase separation is studied theoretically for two-component membranes that can phase separate into two fluid phases such as liquid-ordered and liquid-disordered phases. Many adhesion geometries provide two different environments for these membranes and then partition the membranes into two segments that differ in their composition. Examples are provided by adhering vesicles, by hole- or pore-spanning membranes, and by membranes supported by chemically patterned surfaces. Generalizing a lattice model for binary mixtures to these adhesion geometries, we show that the phase behavior of the adhering membranes depends, apart from composition and temperature, on two additional parameters, the area fraction of one membrane segment and the affinity contrast between the two segments. For the generic case of non-vanishing affinity contrast, the adhering membranes undergo two distinct phase transitions and the phase diagrams in the composition/temperature plane have a generic topology that consists of two two-phase coexistence regions separated by an intermediate one-phase region. As a consequence, phase separation and domain formation is predicted to occur separately in each of the two membrane segments but not in both segments simultaneously. Furthermore, adhesion is also predicted to suppress the phase separation process for certain regions of the phase diagrams. These generic features of the adhesion-induced phase behavior are accessible to experiment.

  8. Dense with Sense

    Science.gov (United States)

    Aletras, Anthony H.; Ingkanisorn, W. Patricia; Mancini, Christine; Arai, Andrew E.

    2005-09-01

    Displacement encoding with stimulated echoes (DENSE) with a low encoding strength phase-cycled meta-DENSE readout and a two fold SENSE acceleration ( R = 2) is described. This combination reduces total breath-hold times for increased patient comfort during cardiac regional myocardial contractility studies. Images from phantoms, normal volunteers, and a patient are provided to demonstrate the SENSE-DENSE combination of methods. The overall breath-hold time is halved while preserving strain map quality.

  9. Indications for a critical point in the phase diagram for hot and dense nuclear matter

    Science.gov (United States)

    Lacey, Roy A.

    2016-12-01

    Two-pion interferometry measurements are studied for a broad range of collision centralities in Au+Au (√{sNN} = 7.7- 200 GeV) and Pb+Pb (√{sNN} = 2.76 TeV) collisions. They indicate non-monotonic excitation functions for the Gaussian emission source radii difference (Rout -Rside), suggestive of reaction trajectories which spend a fair amount of time near a soft point in the equation of state (EOS) that coincides with the critical end point (CEP). A Finite-Size Scaling (FSS) analysis of these excitation functions, provides further validation tests for the CEP. It also indicates a second order phase transition at the CEP, and the values Tcep ∼ 165 MeV and μBcep ∼ 95 MeV for its location in the (T ,μB)-plane of the phase diagram. The static critical exponents (ν ≈ 0.66 and γ ≈ 1.2) extracted via the same FSS analysis, place this CEP in the 3D Ising model (static) universality class. A Dynamic Finite-Size Scaling analysis of the excitation functions, gives the estimate z ∼ 0.87 for the dynamic critical exponent, suggesting that the associated critical expansion dynamics is dominated by the hydrodynamic sound mode.

  10. Imidazolium-Functionalized Poly(arylene ether sulfone) Anion-Exchange Membranes Densely Grafted with Flexible Side Chains for Fuel Cells.

    Science.gov (United States)

    Guo, Dong; Lai, Ao Nan; Lin, Chen Xiao; Zhang, Qiu Gen; Zhu, Ai Mei; Liu, Qing Lin

    2016-09-28

    With the intention of optimizing the performance of anion-exchange membranes (AEMs), a set of imidazolium-functionalized poly(arylene ether sulfone)s with densely distributed long flexible aliphatic side chains were synthesized. The membranes made from the as-synthesized polymers are robust, transparent, and endowed with microphase segregation capability. The ionic exchange capacity (IEC), hydroxide conductivity, water uptake, thermal stability, and alkaline resistance of the AEMs were evaluated in detail for fuel cell applications. Morphological observation with the use of atomic force microscopy and small-angle X-ray scattering reveals that the combination of high-local-density-type and side-chain-type architectures induces distinguished nanophase separation in the AEMs. The as-prepared membranes have advantages in effective water management and ionic conductivity over traditional main-chain polymers. Typically, the conductivity and IEC were in the ranges of 57.3-112.5 mS cm(-1) and 1.35-1.84 mequiv g(-1) at 80 °C, respectively. Furthermore, the membranes exhibit good thermal and alkaline stability and achieve a peak power density of 114.5 mW cm(-2) at a current density of 250.1 mA cm(-2). Therefore, the present polymers containing clustered flexible pendent aliphatic imidazolium promise to be attractive AEM materials for fuel cells.

  11. An asymmetric tubular ceramic-carbonate dual phase membrane for high temperature CO2 separation.

    Science.gov (United States)

    Dong, Xueliang; Ortiz Landeros, José; Lin, Y S

    2013-10-25

    For the first time, a tubular asymmetric ceramic-carbonate dual phase membrane was prepared by a centrifugal casting technique and used for high temperature CO2 separation. This membrane shows high CO2 permeation flux and permeance.

  12. Role of curvature and phase transition in lipid sorting and fission of membrane tubules.

    Science.gov (United States)

    Roux, Aurélien; Cuvelier, Damien; Nassoy, Pierre; Prost, Jacques; Bassereau, Patricia; Goud, Bruno

    2005-04-20

    We have recently developed a minimal system for generating long tubular nanostructures that resemble tubes observed in vivo with biological membranes. Here, we studied membrane tube pulling in ternary mixtures of sphingomyelin, phosphatidylcholine and cholesterol. Two salient results emerged: the lipid composition is significantly different in the tubes and in the vesicles; tube fission is observed when phase separation is generated in the tubes. This shows that lipid sorting may depend critically on both membrane curvature and phase separation. Phase separation also appears to be important for membrane fission in tubes pulled out of giant liposomes or purified Golgi membranes.

  13. Ca2+-induced phase separation in the membrane of palmitate-containing liposomes and its possible relation to membrane permeabilization.

    Science.gov (United States)

    Agafonov, Alexey V; Gritsenko, Elena N; Shlyapnikova, Elena A; Kharakoz, Dmitry P; Belosludtseva, Natalia V; Lezhnev, Enrik I; Saris, Nils-Erik L; Mironova, Galina D

    2007-01-01

    A Ca(2+)-induced phase separation of palmitic acid (PA) in the membrane of azolectin unilamellar liposomes has been demonstrated with the fluorescent membrane probe nonyl acridine orange (NAO). It has been shown that NAO, whose fluorescence in liposomal membranes is quenched in a concentration-dependent way, can be used to monitor changes in the volume of lipid phase. The incorporation of PA into NAO-labeled liposomes increased fluorescence corresponding to the expansion of membrane. After subsequent addition of Ca(2+), fluorescence decreased, which indicated separation of PA/Ca(2+) complexes into distinct membrane domains. The Ca(2+)-induced phase separation of PA was further studied in relation to membrane permeabilization caused by Ca(2+) in the PA-containing liposomes. A supposition was made that the mechanism of PA/Ca(2+)-induced membrane permeabilization relates to the initial stage of Ca(2+)-induced phase separation of PA and can be considered as formation of fast-tightening lipid pores due to chemotropic phase transition in the lipid bilayer.

  14. Detection of molecular interactions at membrane surfaces through colloid phase transitions

    Science.gov (United States)

    Baksh, Michael M.; Jaros, Michal; Groves, Jay T.

    2004-01-01

    The molecular architecture of-and biochemical processes within-cell membranes play important roles in all living organisms, with many drugs and infectious disease agents targeting membranes. Experimental studies of biochemical reactions on membrane surfaces are challenging, as they require a membrane environment that is fluid (like cell membranes) but nevertheless allows for the efficient detection and characterization of molecular interactions. One approach uses lipid membranes supported on solid substrates such as silica or polymers: although the membrane is trapped near the solid interface, it retains natural fluidity and biological functionality and can be implanted with membrane proteins for functional studies. But the detection of molecular interactions involving membrane-bound species generally requires elaborate techniques, such as surface plasmon resonance or total internal reflection fluorescence microscopy. Here we demonstrate that colloidal phase transitions of membrane-coated silica beads provide a simple and label-free method for monitoring molecular interactions on lipid membrane surfaces. By adjusting the lipid membrane composition and hence the pair interaction potential between the membrane-supporting silica beads, we poise our system near a phase transition so that small perturbations on the membrane surface induce dramatic changes in the macroscopic organization of the colloid. We expect that this approach, used here to probe with high sensitivity protein binding events at membrane surfaces, can be applied to study a broad range of cell membrane processes.

  15. Changes in the myosin secondary structure and shrimp surimi gel strength induced by dense phase carbon dioxide.

    Science.gov (United States)

    Guo, Minghui; Liu, Shucheng; Ismail, Marliya; Farid, Mohammed M; Ji, Hongwu; Mao, Weijie; Gao, Jing; Li, Chengyong

    2017-07-15

    Dense phase carbon dioxide (DPCD) could induce protein conformation changes. Myosin and shrimp surimi from Litopenaeus vannamei were treated with DPCD at 5-25MPa and 40-60°C for 20min. Myosin secondary structure was investigated by circular dichroism and shrimp surimi gel strength was determined using textural analysis to develop correlations between them. DPCD had a greater effect on secondary structure and gel strength than heating. With increasing pressure and temperature, the α-helix content of DPCD-treated myosin decreased, while the β-sheet, β-turn and random coil contents increased, and the shrimp surimi gel strength increased. The α-helix content was negatively correlated with gel strength, while the β-sheet, β-turn and random coil contents were positively correlated with gel strength. Therefore, when DPCD induced myosin to form a gel, the α-helix of myosin was unfolded and gradually converted to a β-sheet. Such transformations led to protein-protein interactions and cross-linking, which formed a three-dimensional network to enhance the gel strength.

  16. Effect of ceramide acyl chain length on skin permeability and thermotropic phase behavior of model stratum corneum lipid membranes.

    Science.gov (United States)

    Janůšová, Barbora; Zbytovská, Jarmila; Lorenc, Petr; Vavrysová, Helena; Palát, Karel; Hrabálek, Alexandr; Vávrová, Kateřina

    2011-03-01

    Stratum corneum ceramides play an essential role in the barrier properties of skin. However, their structure-activity relationships are poorly understood. We investigated the effects of acyl chain length in the non-hydroxy acyl sphingosine type (NS) ceramides on the skin permeability and their thermotropic phase behavior. Neither the long- to medium-chain ceramides (8-24 C) nor free sphingosine produced any changes of the skin barrier function. In contrast, the short-chain ceramides decreased skin electrical impedance and increased skin permeability for two marker drugs, theophylline and indomethacin, with maxima in the 4-6C acyl ceramides. The thermotropic phase behavior of pure ceramides and model stratum corneum lipid membranes composed of ceramide/lignoceric acid/cholesterol/cholesterol sulfate was studied by differential scanning calorimetry and infrared spectroscopy. Differences in thermotropic phase behavior of these lipids were found: those ceramides that had the greatest impact on the skin barrier properties displayed the lowest phase transitions and formed the least dense model stratum corneum lipid membranes at 32°C. In conclusion, the long hydrophobic chains in the NS-type ceramides are essential for maintaining the skin barrier function. However, this ability is not shared by their short-chain counterparts despite their having the same polar head structure and hydrogen bonding ability. Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Lipid membrane partitioning of lysolipids and fatty acids: Effects of membrane phase structure and detergent chain length

    DEFF Research Database (Denmark)

    Høyrup, Lise Pernille Kristine; Davidsen, Jesper; Jørgensen, Kent

    2001-01-01

    The lipid membrane partitioning of lysolipids (lysoPC) and fatty acids (FA) into unilamellar vesicles composed of saturated DC$-16$/PC phospholipids has been determined by means of isothermal titration calorimetry (ITC). The calorimetric titrations were performed at low temperatures in the ordered...... gel phase and at high temperatures in the disordered fluid phase of the phospholipid membrane vesicles. The long saturated acyl chains of the lysolipids and fatty acids varied from 10 to 16 carbon atoms and all titrations were performed below the critical micellar concentrations (cmc....... Oppositely, the membrane partitioning of fatty acids depends only weakly on the phase structure of the phospholipid vesicles. In addition, the thermodynamic measurements show that the partition coefficients for both the lysolipids and fatty acids toward gel and fluid lipid membranes become almost an order...

  18. Phase behavior of multicomponent membranes: Experimental and computational techniques

    DEFF Research Database (Denmark)

    Bagatolli, Luis; Kumar, P.B. Sunil

    2009-01-01

    membranes. Current increase in interest in the domain formation in multicomponent membranes also stems from the experiments demonstrating liquid ordered-liquid disordered coexistence in mixtures of lipids and cholesterol and the success of several computational models in predicting their behavior....... This review includes basic foundations on membrane model systems and experimental approaches applied in the membrane research area, stressing on recent advances in the experimental and computational techniques....

  19. Method of Making Reaction Induced Phase Separation Membranes and Uses Thereof

    KAUST Repository

    Peinemann, Klaus-Viktor

    2017-08-10

    Provided herein are methods of making asymmetric membranes comprising a first layer and a second layer. The methods include preparing a polymeric solution comprising one or more polymers, casting the polymeric solution to form a polymeric film, contacting the polymeric film with a solvent comprising a crosslinker under conditions to form a first layer on the top of the film, wherein the first layer is dense and solvent resistant, and contacting the polymeric film having the dense, solvent-resistant first layer with a non-solvent solution under conditions that form a porous second layer on the bottom of the film.

  20. Two-phase flow for fouling control in membranes

    NARCIS (Netherlands)

    Wibisono, Yusuf

    2014-01-01

    The real challenge of the use of NF/RO spiral-wound membrane modules in water treatment is membrane fouling. Fouling problems in NF/RO systems are more complicated than in low pressure membrane processes, becaused fouling usually occurs on the nanoscale, combined with the complex geometry of spiral-

  1. Ultra resolution chemical fingerprinting of dense non-aqueous phase liquids from manufactured gas plants by reversed phase comprehensive two-dimensional gas chromatography.

    Science.gov (United States)

    McGregor, Laura A; Gauchotte-Lindsay, Caroline; Daéid, Niamh Nic; Thomas, Russell; Daly, Paddy; Kalin, Robert M

    2011-07-22

    Ultra resolution chemical fingerprinting of dense non-aqueous phase liquids (DNAPLs) from former manufactured gas plants (FMGPs) was investigated using comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry (GC×GC TOFMS). Reversed phase GC×GC (i.e. a polar primary column coupled to a non-polar secondary column) was found to significantly improve the separation of polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues. Sample extraction and cleanup was performed simultaneously using accelerated solvent extraction (ASE), with recovery rates between 76% and 97%, allowing fast, efficient extraction with minimal solvent consumption. Principal component analysis (PCA) of the GC×GC data was performed in an attempt to differentiate between twelve DNAPLs based on their chemical composition. Correlations were discovered between DNAPL composition and historic manufacturing processes used at different FMGP sites. Traditional chemical fingerprinting methods generally follow a tiered approach with sample analysis on several different instruments. We propose ultra resolution chemical fingerprinting as a fast, accurate and precise method of obtaining more chemical information than traditional tiered approaches while using only a single analytical technique.

  2. Dense core secretory vesicles revealed as a dynamic Ca2+ store in neuroendocrine cells with a vesicle-associated membrane protein aequorin chimaera

    Science.gov (United States)

    Mitchell, Kathryn J.; Pinton, Paolo; Varadi, Aniko; Tacchetti, Carlo; Ainscow, Edward K.; Pozzan, Tullio; Rizzuto, Rosario; Rutter, Guy A.

    2001-01-01

    The role of dense core secretory vesicles in the control of cytosolic-free Ca2+ concentrations ([Ca2+]c) in neuronal and neuroendocrine cells is enigmatic. By constructing a vesicle-associated membrane protein 2–synaptobrevin.aequorin chimera, we show that in clonal pancreatic islet β-cells: (a) increases in [Ca2+]c cause a prompt increase in intravesicular-free Ca2+ concentration ([Ca2+]SV), which is mediated by a P-type Ca2+-ATPase distinct from the sarco(endo) plasmic reticulum Ca2+-ATPase, but which may be related to the PMR1/ATP2C1 family of Ca2+ pumps; (b) steady state Ca2+ concentrations are 3–5-fold lower in secretory vesicles than in the endoplasmic reticulum (ER) or Golgi apparatus, suggesting the existence of tightly bound and more rapidly exchanging pools of Ca2+; (c) inositol (1,4,5) trisphosphate has no impact on [Ca2+]SV in intact or permeabilized cells; and (d) ryanodine receptor (RyR) activation with caffeine or 4-chloro-3-ethylphenol in intact cells, or cyclic ADPribose in permeabilized cells, causes a dramatic fall in [Ca2+]SV. Thus, secretory vesicles represent a dynamic Ca2+ store in neuroendocrine cells, whose characteristics are in part distinct from the ER/Golgi apparatus. The presence of RyRs on secretory vesicles suggests that local Ca2+-induced Ca2+ release from vesicles docked at the plasma membrane could participate in triggering exocytosis. PMID:11571310

  3. Dense core secretory vesicles revealed as a dynamic Ca(2+) store in neuroendocrine cells with a vesicle-associated membrane protein aequorin chimaera.

    Science.gov (United States)

    Mitchell, K J; Pinton, P; Varadi, A; Tacchetti, C; Ainscow, E K; Pozzan, T; Rizzuto, R; Rutter, G A

    2001-10-01

    The role of dense core secretory vesicles in the control of cytosolic-free Ca(2+) concentrations ([Ca(2+)](c)) in neuronal and neuroendocrine cells is enigmatic. By constructing a vesicle-associated membrane protein 2-synaptobrevin.aequorin chimera, we show that in clonal pancreatic islet beta-cells: (a) increases in [Ca(2+)](c) cause a prompt increase in intravesicular-free Ca(2+) concentration ([Ca(2+)]SV), which is mediated by a P-type Ca(2+)-ATPase distinct from the sarco(endo) plasmic reticulum Ca(2+)-ATPase, but which may be related to the PMR1/ATP2C1 family of Ca(2+) pumps; (b) steady state Ca(2+) concentrations are 3-5-fold lower in secretory vesicles than in the endoplasmic reticulum (ER) or Golgi apparatus, suggesting the existence of tightly bound and more rapidly exchanging pools of Ca(2+); (c) inositol (1,4,5) trisphosphate has no impact on [Ca(2+)](SV) in intact or permeabilized cells; and (d) ryanodine receptor (RyR) activation with caffeine or 4-chloro-3-ethylphenol in intact cells, or cyclic ADPribose in permeabilized cells, causes a dramatic fall in [Ca(2+)](SV). Thus, secretory vesicles represent a dynamic Ca(2+) store in neuroendocrine cells, whose characteristics are in part distinct from the ER/Golgi apparatus. The presence of RyRs on secretory vesicles suggests that local Ca(2+)-induced Ca(2+) release from vesicles docked at the plasma membrane could participate in triggering exocytosis.

  4. Effect of Humic Acid on Migration, Distribution and Remediation of Dense Non-aqueous Phase Liquids: A laboratory investigation

    Science.gov (United States)

    Cheng, Z.; Wu, J.; Xu, H.; Gao, Y.

    2014-12-01

    Over the last decades, dense non-aqueous phase liquids (DNAPLs) contamination in the subsurface increases with the rapid development of oil industry and becomes the focus of many studies. The migration, distribution and remediation efficiency of DNAPLs in the subsurface environment are greatly affected by the solution chemistry besides the physical heterogeneities of aquifers. Humic acid (HA), which is ubiquitous in natural environments, is a surface active substance exhibiting solubility enhancement behavior for hydrophobic organic compounds such as DNAPLs. Here we reported a laboratory investigation to study the effects of HA on the infiltration, immobilization and subsequent recovery of DNAPL in porous media. Tetrachloroethylene (PCE) was selected as the representative DNAPL in this study. Two-dimensional (2-D) sandbox experiments were conducted to investigate the effects of different HA concentrations on the transport, distribution of PCE and the remediation of PCE using surfactant (Tween 80) flushing in a saturated porous media system. The surfactant flushing of PCE was performed after the PCE transport and distribution had reached equilibrium. A light transmission visualization method with charge-coupled device (CCD) camera was adopted to visualize PCE distribution and quantify its saturation. In addition, the experiments were also designed to gather data for the validation of multiphase flow models. Effluent samples were collected to determine dissolved PCE concentrations. PCE solubilization and PCE-water interfacial tension were experimentally determined in aqueous solutions of varying HA concentrations. The experimental results showed that the presence of HA can have a dramatic impact on PCE flow and entrapment, and significantly improved the recovery of PCE during surfactant enhanced aquifer remediation (SEAR). The findings are of use for better understanding of the migration and entrapment of DNAPLs and developing of SEAR technology.

  5. Vascular endothelial cell membranes differentiate between stretch and shear stress through transitions in their lipid phases.

    Science.gov (United States)

    Yamamoto, Kimiko; Ando, Joji

    2015-10-01

    Vascular endothelial cells (ECs) respond to the hemodynamic forces stretch and shear stress by altering their morphology, functions, and gene expression. However, how they sense and differentiate between these two forces has remained unknown. Here we report that the plasma membrane itself differentiates between stretch and shear stress by undergoing transitions in its lipid phases. Uniaxial stretching and hypotonic swelling increased the lipid order of human pulmonary artery EC plasma membranes, thereby causing a transition from the liquid-disordered phase to the liquid-ordered phase in some areas, along with a decrease in membrane fluidity. In contrast, shear stress decreased the membrane lipid order and increased membrane fluidity. A similar increase in lipid order occurred when the artificial lipid bilayer membranes of giant unilamellar vesicles were stretched by hypotonic swelling, indicating that this is a physical phenomenon. The cholesterol content of EC plasma membranes significantly increased in response to stretch but clearly decreased in response to shear stress. Blocking these changes in the membrane lipid order by depleting membrane cholesterol with methyl-β-cyclodextrin or by adding cholesterol resulted in a marked inhibition of the EC response specific to stretch and shear stress, i.e., phosphorylation of PDGF receptors and phosphorylation of VEGF receptors, respectively. These findings indicate that EC plasma membranes differently respond to stretch and shear stress by changing their lipid order, fluidity, and cholesterol content in opposite directions and that these changes in membrane physical properties are involved in the mechanotransduction that activates membrane receptors specific to each force.

  6. Dynamic quenchers in fluorescently labeled membranes. Theory for quenching in a three-phase system.

    Science.gov (United States)

    Omann, G M; Glaser, M

    1985-05-01

    The theory for quenching of fluorescently labeled membranes by dynamic quenchers is described for a three-phase system: a fluorescently labeled membrane, a nonlabeled membrane, and an aqueous phase. Two different experimental protocols are possible to determine quenching parameters. Using the first protocol, partition coefficients and bimolecular quenching constants were determined for a hydrophobic quencher in carbazole-labeled membranes in the presence of an unlabeled reference membrane. These parameters determined for 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) using this three-phase analysis were in good agreement with values determined by a two-phase analysis without the reference lipid. Hence, the theory was verified. In the second protocol, the quencher partition coefficient was determined for unlabeled membranes in the presence of a carbazole-labeled reference membrane. Partition coefficients for DDE determined by this method were the same as partition coefficients determined for carbazole-labeled membranes using the two-phase analysis. The greater ease in determining partition coefficients and bimolecular quenching constants by the three-phase analysis and, in particular, the ability to determine the partition coefficient in unlabeled membranes make the three-phase analysis especially useful. This method was used to study the effect varying the membrane lipid composition has on the partition coefficient. The data indicate that partition coefficients of DDE in fluid membranes are not dramatically dependent upon polar head group composition, fatty acid composition, or cholesterol content. However, partitioning into gel-phase lipids is at least 100-fold less than fluid-phase lipids.

  7. Pre-Combustion Carbon Dioxide Capture by a New Dual Phase Ceramic-Carbonate Membrane Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jerry

    2014-09-30

    This report documents synthesis, characterization and carbon dioxide permeation and separation properties of a new group of ceramic-carbonate dual-phase membranes and results of a laboratory study on their application for water gas shift reaction with carbon dioxide separation. A series of ceramic-carbonate dual phase membranes with various oxygen ionic or mixed ionic and electronic conducting metal oxide materials in disk, tube, symmetric, and asymmetric geometric configurations was developed. These membranes, with the thickness of 10 μm to 1.5 mm, show CO2 permeance in the range of 0.5-5×10-7 mol·m-2·s-1·Pa-1 in 500-900oC and measured CO2/N2 selectivity of up to 3000. CO2 permeation mechanism and factors that affect CO2 permeation through the dual-phase membranes have been identified. A reliable CO2 permeation model was developed. A robust method was established for the optimization of the microstructures of ceramic-carbonate membranes. The ceramic-carbonate membranes exhibit high stability for high temperature CO2 separations and water gas shift reaction. Water gas shift reaction in the dual-phase membrane reactors was studied by both modeling and experiments. It is found that high temperature syngas water gas shift reaction in tubular ceramic-carbonate dual phase membrane reactor is feasible even without catalyst. The membrane reactor exhibits good CO2 permeation flux, high thermal and chemical stability and high thermal shock resistance. Reaction and separation conditions in the membrane reactor to produce hydrogen of 93% purity and CO2 stream of >95% purity, with 90% CO2 capture have been identified. Integration of the ceramic-carbonate dual-phase membrane reactor with IGCC process for carbon dioxide capture was analyzed. A methodology was developed to identify optimum operation conditions for a membrane tube of given dimensions that would treat coal syngas with targeted performance. The calculation results show that the dual-phase membrane reactor could

  8. Pre-Combustion Carbon Dioxide Capture by a New Dual Phase Ceramic-Carbonate Membrane Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jerry Y. S. [Arizona State Univ., Tempe, AZ (United States)

    2015-01-31

    This report documents synthesis, characterization and carbon dioxide permeation and separation properties of a new group of ceramic-carbonate dual-phase membranes and results of a laboratory study on their application for water gas shift reaction with carbon dioxide separation. A series of ceramic-carbonate dual phase membranes with various oxygen ionic or mixed ionic and electronic conducting metal oxide materials in disk, tube, symmetric, and asymmetric geometric configurations was developed. These membranes, with the thickness of 10 μm to 1.5 mm, show CO2 permeance in the range of 0.5-5×10-7 mol·m-2·s-1·Pa-1 in 500-900°C and measured CO2/N2 selectivity of up to 3000. CO2 permeation mechanism and factors that affect CO2 permeation through the dual-phase membranes have been identified. A reliable CO2 permeation model was developed. A robust method was established for the optimization of the microstructures of ceramic-carbonate membranes. The ceramic-carbonate membranes exhibit high stability for high temperature CO2 separations and water gas shift reaction. Water gas shift reaction in the dual-phase membrane reactors was studied by both modeling and experiments. It is found that high temperature syngas water gas shift reaction in tubular ceramic-carbonate dual phase membrane reactor is feasible even without catalyst. The membrane reactor exhibits good CO2 permeation flux, high thermal and chemical stability and high thermal shock resistance. Reaction and separation conditions in the membrane reactor to produce hydrogen of 93% purity and CO2 stream of >95% purity, with 90% CO2 capture have been identified. Integration of the ceramic-carbonate dual-phase membrane reactor with IGCC process for carbon dioxide capture was analyzed. A methodology was developed to identify optimum operation conditions for a

  9. COOH-terminal isoleucine of lysosome-associated membrane protein-1 is optimal for its efficient targeting to dense secondary lysosomes.

    Science.gov (United States)

    Akasaki, Kenji; Suenobu, Michihisa; Mukaida, Maki; Michihara, Akihiro; Wada, Ikuo

    2010-12-01

    Lysosome-associated membrane protein-1 (LAMP-1) consists of a highly glycosylated luminal domain, a single-transmembrane domain and a short cytoplasmic tail that possesses a lysosome-targeting signal (GYQTI(382)) at the COOH terminus. It is hypothesized that the COOH-terminal isoleucine, I(382), could be substituted with any other bulky hydrophobic amino acid residue for LAMP-1 to exclusively localize in lysosomes. In order to test this hypothesis, we compared subcellular distribution of four substitution mutants with phenylalanine, leucine, methionine and valine at the COOH-terminus (termed I382F, I382L, I382M and I382V, respectively) with that of wild-type (WT)-LAMP-1. Double-labelled immunofluorescence analyses showed that these substitution mutants were localized as significantly to late endocytic organelles as WT-LAMP-1. However, the quantitative subcellular fractionation study revealed different distribution of WT-LAMP-1 and these four COOH-terminal mutants in late endosomes and dense secondary lysosomes. WT-LAMP-1 was accumulated three to six times more in the dense lysosomal fraction than the four mutants. The level of WT-LAMP-1 in late endosomal fraction was comparable to those of I382F, I382M and I382V. Conversely, I382L in the late endosomal fraction was approximately three times more abundant than WT-LAMP-1. These findings define the presence of isoleucine residue at the COOH-terminus of LAMP-1 as critical in governing its efficient delivery to secondary lysosomes and its ratio of lysosomes to late endosomes.

  10. Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review

    KAUST Repository

    Guillen, Gregory R.

    2011-04-06

    The methods and mechanisms of nonsolvent induced phase separation have been studied for more than fifty years. Today, phase inversion membranes are widely used in numerous chemical industries, biotechnology, and environmental separation processes. The body of knowledge has grown exponentially in the past fifty years, which suggests the need for a critical review of the literature. Here we present a review of nonsolvent induced phase separation membrane preparation and characterization for many commonly used membrane polymers. The key factors in membrane preparation discussed include the solvent type, polymer type and concentration, nonsolvent system type and composition, additives to the polymer solution, and film casting conditions. A brief introduction to membrane characterization is also given, which includes membrane porosity and pore size distribution characterization, membrane physical and chemical properties characterization, and thermodynamic and kinetic evaluation of the phase inversion process. One aim of this review is to lay out the basics for selecting polymer solvent nonsolvent systems with appropriate film casting conditions to produce membranes with the desired performance, morphology, and stability, and to choose the proper way to characterize these properties of nonsolvent induced phase inversion membranes. © 2011 American Chemical Society.

  11. Modelling ruptures of buried high-pressure dense-phase CO2 pipelines in carbon capture and storage applications - Part II. A full-scale rupture

    OpenAIRE

    Wareing, CJ; Fairweather, M.; Falle, SAEG; Woolley, RM

    2015-01-01

    Carbon capture and storage (CCS) presents a short-term option for significantly reducing the amount of carbon dioxide (CO2) released into the atmosphere. National Grid initiated the COOLTRANS research programme to consider the CCS pipeline transportation of high-pressure dense-phase CO2, including the development and application of a mathematical model for predicting the sonic near-field dispersion of pure CO2 following pipeline venting or failure. In Part I (Wareing et al., 2015a) validation...

  12. Characterization of Polysulfone Membranes Prepared with Thermally Induced Phase Separation Technique

    Science.gov (United States)

    Tiron, L. G.; Pintilie, Ș C.; Vlad, M.; Birsan, I. G.; Baltă, Ș

    2017-06-01

    Abstract Membrane technology is one of the most used water treatment technology because of its high removal efficiency and cost effectiveness. Preparation techniques for polymer membranes show an important aspect of membrane properties. Generally, polysulfone (PSf) and polyethersulfone (PES) are used for the preparation of ultrafiltration (UF) membranes. Polysulfone (PSf) membranes have been widely used for separation and purification of different solutions because of their excellent chemical and thermal stability. Polymeric membranes were obtained by phase inversion method. The polymer solution introduced in the nonsolvent bath (distilled water) initiate the evaporation of the solvent from the solution, this phenomenon has a strong influence on the transport properties. The effect of the coagulation bath temperature on the membrane properties is of interest for this study. Membranes are characterized by pure water flux, permeability, porosity and retention of methylene blue. The low temperature of coagulation bath improve the membrane’s rejection and its influence was most notable.

  13. Dense Breasts

    Science.gov (United States)

    ... also appear white on mammography, they can be hidden by or within dense breast tissue. Other imaging ... understanding of the possible charges you will incur. Web page review process: This Web page is reviewed ...

  14. PREPARATION OF EVOH MICROPOROUS MEMBRANES via THERMALLY INDUCED PHASE SEPARATION USING BINARY SOLVENTS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Microporous ethylene-vinyl alcohol copolymer (EVOH) flat membranes and hollow-fiber membranes with 38 mol% ethylene content were prepared via thermally induced phase separation (TIPS) using the mixture of 1,4-butanediol and poly(ethylene glycol)(PEG400) as diluents. Effects of the ratio of 1,4-butanediol to PEG400 on the phase diagrams, phase separation mechanism and membrane morphology were studied by small angle light scattering (SALS) measurements, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). It was found that by varying the composition of the binary solvent, the phase diagrams and membrane morphology can be controlled successfully. Moreover, the phase diagrams showed that broader regions of Liquid-Liquid (L-L) phase separation were obtained, as well as closer distances between L-L phase separation lines and Solid-Liquid (S-L) phase separation lines. Interconnected structures observed both in the flat membrane and hollow fiber membrane consist with the above results.

  15. Characterization of Polyamide 66 membranes prepared by phase inversion using formic acid and hydrochloric acid such as solvents

    Directory of Open Access Journals (Sweden)

    Patrícia Poletto

    2011-12-01

    Full Text Available The membranes properties prepared from water/formic acid (FA/ polyamide 66 (PA66 and water/hydrochloric acid (HCl/polyamide 66 (PA 66 systems has been studied. The different solvents interact distinctly with the polymer, affecting the membrane morphology. The asymmetric structure of the membranes showed a dense top layer and a porous sublayer. The membranes M-HCl prepared from HCl/PA 66 system showed a larger dense layer (around 23 μm in compared to those prepared from FA/PA 66 system (M-FA (around 10 μm. The membrane morphology was a determinant factor in results of water absorption, porosity and pure water flux. The lower thickness of dense layer in M-FA membranes resulted in a higher water absorption and, consequently, porosity, approximately 50%, compared with M-HCl membranes, approximately 15%. The same trend was observed to permeate flux, the lower thickness of dense layer higher pure water flux.

  16. Vertical pneumatic conveying in dilute and dense-phase flows: experimental study of the influence of particle density and diameter on fluid dynamic behavior

    Directory of Open Access Journals (Sweden)

    Narimatsu C.P.

    2001-01-01

    Full Text Available In this work, the effects of particle size and density on the fluid dynamic behavior of vertical gas-solid transport of Group D particles in a 53.4 mm diameter transport tube were studied. For the conditions tested, the experimental curves of pressure gradient versus air velocity presented a minimum pressure gradient point, which is associated with a change in the flow regime from dense to dilute phase. The increases in particle size from 1.00 to 3.68 mm and in density from 935 to 2500 kg/m³ caused an increase in pressure gradient for the dense-phase transport region, but were not relevant in dilute transport. The transition velocity between dense and dilute flow (Umin also increased with increasing particle density and diameter. An empirical equation was fitted for predicting transition air velocity for the transport of glass spheres. Additional experiments, covering a wider range of conditions and particles properties, are still needed to allow the fitting of a generalized equation for prediction of Umin.

  17. Phase-inversion tape-casting preparation and significant performance enhancement of Ce0.9Gd0.1O1.95- La0.6Sr0.4Co0.2Fe0.8O3-δ dual-phase asymmetric membrane for oxygen separation

    DEFF Research Database (Denmark)

    Huang, Hua; Cheng, Shiyang; Gao, Jianfeng;

    2014-01-01

    The dual-phase Ce0.9Gd0.1O1.95–La0.6Sr0.4Co0.2Fe0.8O3−δ asymmetric membrane was prepared via a phase-inversion tape-casting method. The membrane consisted of a thicker porous support layer and a thinner dense layer. When the dense side of the membrane was coated with a La0.6Sr0.4CoO3−δ catalytic...... activation layer, the oxygen permeation flux was markedly increased by a factor of 4.1–5.6, reaching 0.45 mL cm−2 min−1 at 900 °C. The flux increase can be attributed to enhanced surface oxygen exhange kinetics....

  18. Reactivity of Phenol Allylation Using Phase-Transfer Catalysis in Ion-Exchange Membrane Reactor

    Directory of Open Access Journals (Sweden)

    Ho Shing Wu

    2012-01-01

    Full Text Available This study investigates the reactivity of phenol allylation using quaternary ammonium salt as a phase-transfer catalyst in three types of membrane reactors. Optimum reactivity and turnover of phenol allylation were obtained using a respond surface methodology. The contact angle, water content, and degree of crosslinkage were measured to understand the microenvironment in the ion exchange membrane.

  19. Phase diagrams of lipid mixtures relevant to the study of membrane rafts

    DEFF Research Database (Denmark)

    Goni, Felix; Alonso, Alicia; Bagatolli, Luis

    2008-01-01

    The present paper reviews the phase properties of phosphatidylcholine-sphingomyelin-cholesterol mixtures, that are often used as models for membrane "raft" microdomains. The available data based on X-ray, microscopic and spectroscopic observations, surface pressure and calorimetric measurements, ...

  20. Phase diagrams of lipid mixtures relevant to the study of membrane rafts

    DEFF Research Database (Denmark)

    Goni, Felix; Alonso, Alicia; Bagatolli, Luis

    2008-01-01

    The present paper reviews the phase properties of phosphatidylcholine-sphingomyelin-cholesterol mixtures, that are often used as models for membrane "raft" microdomains. The available data based on X-ray, microscopic and spectroscopic observations, surface pressure and calorimetric measurements, ...

  1. Phase coexistence in a triolein-phosphatidylcholine system. Implications for lysosomal membrane properties.

    Science.gov (United States)

    Pakkanen, Kirsi I; Duelund, Lars; Vuento, Matti; Ipsen, John Hjort

    2010-02-01

    The effects of tri- and monoglycerides on phospholipid (POPC) membranes were studied using spectroscopical methods. Triolein was found to form two types of POPC-rich membranes, both with POPC or as a three-component system with monopalmitin. These two membrane types were determined as co-existing phases based on their spontaneous and stable separation and named heavy and light phase according to their sedimentation behaviour. Marked differences were seen in the physical properties of these phases, even though only minor compositional variation was detected. The light, less polar phase was found to be less ordered and more fluid and seemed to allow significantly lower amount of water penetration into the membrane-water interface than pure POPC membrane. The heavy phase, apart from their slightly altered water penetration, resembled more a pure POPC membrane. As triglycerides are present in lysosomal membranes, the present results can be seen as an implication for polarity-based water permeability barrier possibly contributing to the integrity of lysosomes.

  2. Morphology and Performance of PLLA Based Porous Membranes by Phase Separation Control

    Science.gov (United States)

    Xing, Qian; Dong, Xia; Li, Rongbo; Han, Charles C.; Wang, Dujin

    2013-03-01

    Poly (L-lactic acid) (PLLA) porous membranes with different morphologies and properties were prepared through immersion precipitation method. It has been proved that the rate and level of phase separation between PLLA/dioxane solution and coagulation baths were the original drive force for the ultimate structure and corresponding performance of PLLA membranes. The equilibrium thermodynamic phase diagram of PLLA/solvent/nonsolvent and the kinetic diffusion rate between solvent and nonsolvent were systematically investigated. NSFC 50925313 and 51173195

  3. Enrichment of membrane proteins by partitioning in detergent/polymer aqueous two-phase systems.

    Science.gov (United States)

    Everberg, Henrik; Gustavasson, Niklas; Tjerned, Folke

    2008-01-01

    Methods that combine efficient solubilization with enrichment of proteins and intact protein complexes are of central interest in current membrane proteomics. We have developed methods based on nondenaturing detergent extraction of yeast mitochondrial membrane proteins followed by enrichment of hydrophobic proteins in aqueous two-phase system. Combining the zwitterionic detergent Zwittergent 3-10 and the nonionic detergent Triton X-114 results in a complementary solubilization of proteins, which is similar to that of the anionic detergent sodium dodecyl sulfate (SDS) but with the important advantage of being nondenaturing. Detergent/polymer two-phase system partitioning offers removal of soluble proteins that can be further improved by manipulation of the driving forces governing protein distribution between the phases. Integral and peripheral membrane protein subunits from intact membrane protein complexes partition to the detergent phase while soluble proteins are found in the polymer phase. An optimized solubilization protocol is presented in combination with detergent/polymer two-phase partitioning as a mild and efficient method for initial enrichment of membrane proteins and membrane protein complexes in proteomic studies.

  4. Detectability comparison of simulated objects within a dense breast phantom using high energy x-ray phase sensitive and conventional imaging systems

    Science.gov (United States)

    Ghani, Muhammad U.; Wong, Molly D.; Wu, Di; Zheng, Bin; Chen, Wei; Fajardo, Laurie L.; Wu, Xizeng; Liu, Hong

    2017-02-01

    The objective of this study was to compare the detectability of simulated objects within a dense breast phantom using high energy x-rays for phase sensitive breast imaging in comparison with a conventional imaging system. A 5 cm thick phantom was used which represented a compressed breast consisting of 70% glandular and 30% adipose tissue ratio in non-uniform background. The phantom had a 6 × 6 matrix of holes with milled depths ranging from 1 to 0.1 mm and diameters ranging from 4.25 to 0.25 mm representing simulated tumors. The in-line phase sensitive prototype was equipped with a micro-focus x-ray source and a flat panel detector with a 50 μm pixel pitch, both mounted on an optical rail. Phase contrast image of the phantom was acquired at 120 kVp, 4.5 mAs at source to object distance (SOD) of 68 cm and source to image detector distance (SIDD) of 170 cm with a geometric magnification (M) of 2.5. A 2.5 mm aluminum (Al) filter was used for beam hardening. The conventional image was acquired using the same porotype with the phantom in contact with the detector at 40 kVp, 12.5 mAs under SID = 68 cm. The mean glandular dose (Dg) for both the acquisitions was 1.3 mGy. The observer study and CNR analyses indicated that the phase contrast image had higher disk detectability as compared to the conventional image. The edge enhancement provided by the phase sensitive images warrants in identifying boundaries of malignant tissues and in providing optimal results in phase retrieval process. The potential demonstrated by this study for imaging a dense breast with a high energy phase sensitive x-ray imaging to improve tumor detection in warrants further investigation of this technique.

  5. Predictive Service Life Tests for Roofing Membranes: Phase 1

    Science.gov (United States)

    1993-12-01

    April 1991), pp 37-38, 40, 42, 44, 46. Puterman . M., K.H. Reinhorn, and M. Marton, "Specifications for Quality Assurance of Single-Ply Membrane...Material." Third International Symposium on Roofing Technology (NRCA, 1991), pp 271-275. Puterman , M., I. Soroka, and A. Bentur, "Deterioration of

  6. Tuning of Block Copolymer Membrane Morphology through Water Induced Phase Inversion Technique

    KAUST Repository

    Madhavan, Poornima

    2016-06-01

    Isoporous membranes are attractive for the regulation and detection of transport at the molecular level. A well-defined asymmetric membranes from diblock copolymers with an ordered nanoporous membrane morphologies were fabricated by the combination of block copolymer self-assembly and non-solvent-induced phase separation (NIPS) technique. This is a straightforward and fast one step procedure to develop integrally anisotropic (“asymmetric”) membranes having isoporous top selective layer. Membranes prepared via this method exhibit an anisotropic cross section with a thin separation layer supported from underneath a macroporous support. These membrane poses cylindrical pore structure with ordered nanopores across the entire membrane surfaces with pore size in the range from 20 to 40 nm. Tuning the pore morphology of the block copolymer membranes before and after fabrication are of great interest. In this thesis, we first investigated the pore morphology tuning of asymmetric block copolymer membrane by complexing with small organic molecules. We found that the occurrence of hydrogen-bond formation between PS-b-P4VP block copolymer and –OH/ –COOH functionalized organic molecules significantly tunes the pore morphology of asymmetric nanoporous membranes. In addition, we studied the complexation behavior of ionic liquids with PS-b-P4VP block copolymer in solutions and investigated their effect on final membrane morphology during the non-solvent induced phase separation process. We found that non-protic ionic liquids facilitate the formation of hexagonal nanoporous block copolymer structure, while protic ionic liquids led to a lamella-structured membrane. Secondly, we demonstrated the catalytic activity of the gold nanoparticle-enhanced hollow fiber membranes by the reduction of nitrophenol. Also, we systematically investigated the pore morphology of isoporous PS-b-P4VP using 3D imaging technique. Thirdly, we developed well-distributed silver nanoparticles on the

  7. Effects of oxyethylated glycerol cryoprotectants on phase transitions of DPPC model membranes

    Directory of Open Access Journals (Sweden)

    Kasian N. A.

    2015-04-01

    Full Text Available Aim. To determine the effect of the oxyethylated glycerol cryoprotectants (OEGn with polymerization degrees n = 5, 25, 30 on the phase states and phase transitions of dipalmitoylphosphatidylcholine (DPPC-based model membranes. Methods. Differential scanning calorimetry. Results. Model lipid membranes on water/OEGn and water/glycerol subphases with varying cryoprotectant concentrations from 0 to ~ 100 % w/w were studied. A significant raise in the pre-transition and main phase transition temperatures with increasing OEGn concentration was noted whereas the membrane melting peak persist to 100 % w/w OEGn. A sharp increase in the melting enthalpy was observed for OEGn = 5. Conclusions. The solvating ability of the subphase in DPPC membranes decreases in the order water > glycerol > OEGn = 5 > OEGn = 25 > OEGn = 30, which correlates with the relative number of groups effectively contributing to the solvation process.

  8. The influence of the membrane-polymer interface on colloidal membrane dynamics and phase behavior

    Science.gov (United States)

    Zakhary, Mark J.

    A primary challenge in the field of self-assembly is to identify simple interactions that produce well-defined, complex, and controllable materials. A large part of this task is to creatively engineer appropriate assembly components with such suitable interactions built-in. Here, we demonstrate that rod-like subunits, experimentally modeled by fd bacteriophage viruses, with simple and predictable hard-core repulsive interactions, exhibit a great wealth of fascinating self-assembly behavior. These rods form two-dimensional liquid crystalline colloidal membranes consisting of monolayers of aligned particles owing purely to entropic considerations. Due to surface tension, rods near the edge of the monolayers twist, resulting in an elastic nematic ring surrounding the fluid-like membrane interior, and it is the rich phenomena rooted in the interplay between the edge and the interior that is the subject of this thesis. The chiral nature of the fd subunits causes a symmetry breaking at the membrane edge, which leads to chiral control of interfacial tension and resultantly a controllable, reversible morphological transition between membranes and one-dimensional twisted ribbons. Using optical microscopic and optical tweezer techniques, we show that a nucleation barrier exists in association with the membrane-ribbon transition, and investigate this barrier using fluctuation analysis as well as highly controlled force-extension experiments. The finite bending rigidity of the membrane edge is studied, and we show that long filamentous polymers spontaneously adhere to the edge, introducing the concept of geometrical edge-active agents. By analyzing the suppressed edge fluctuations of filament-bound membranes, it is found that the edge bending rigidity varies by up to an order of magnitude in a predictable and controllable way. Finally, we study the effect of the monolayer edge on the membrane coalescence, and observe two types of stable liquid crystalline defects that form at

  9. Partition behavior of surfactants, butanol, and salt during application of density-modified displacement of dense non-aqueous phase liquids

    Energy Technology Data Exchange (ETDEWEB)

    Damrongsiri, S. [Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Phaya-Thai Rd., Bangkok (Thailand); Tongcumpou, C., E-mail: tchantra@chula.ac.th [Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Phaya-Thai Rd., Bangkok (Thailand); Environmental Research Institute, Chulalongkorn University (Thailand); Sabatini, D.A. [School of Civil Engineering and Environmental Science, The University of Oklahoma, Oklahoma (United States)

    2013-03-15

    Highlights: ► Aqueous surfactant increases the partition of butanol aqueous phase. ► Water partition to NAPL phase via butanol and surfactant in NAPL phase. ► PCE partition to aqueous phase by solubilization into micelles. ► Surfactants cause the dramatically partition of water to NAPL phase. ► Aqueous salt dispels surfactant to NAPL phase. -- Abstract: Density-modified displacement (DMD) is a recent approach for removal of trapped dense NAPL (DNAPL). In this study, butanol and surfactant are contacted with the DNAPL to both reduce the density as well as release the trapped DNAPL (perchloroethylene: PCE). The objective of the study was to determine the distribution of each component (e.g., butanol, surfactant, water, PCE) between the original aqueous and PCE phases during the application of DMD. The results indicated that the presence of the surfactant increased the amount of n-butanol required to make the NAPL phase reach its desired density. In addition, water and anionic surfactant were found to partition along with the BuOH into the PCE phase. The water also found partitioned to reverse micelles in the modified phase. Addition of salt was seen to increase partitioning of surfactant to BuOH containing PCE phase. Subsequently, a large amount of water was solubilized into reverse micelles which lead to significantly increase in volume of the PCE phase. This work thus demonstrates the role of each component and the implications for the operation design of an aquifer treatment using the DMD technique.

  10. Dense and high-stability Ti2AlN MAX phase coatings prepared by the combined cathodic arc/sputter technique

    Science.gov (United States)

    Wang, Zhenyu; Liu, Jingzhou; Wang, Li; Li, Xiaowei; Ke, Peiling; Wang, Aiying

    2017-02-01

    Ti2AlN belongs to a family of ternary nano-laminate alloys known as the MAX phases, which exhibit a unique combination of metallic and ceramic properties. In the present work, the dense and high-stability Ti2AlN coating has been successfully prepared through the combined cathodic arc/sputter deposition, followed by heat post-treatment. It was found that the as-deposited Ti-Al-N coating behaved a multilayer structure, where (Ti, N)-rich layer and Al-rich layer grew alternately, with a mixed phase constitution of TiN and TiAlx. After annealing at 800 °C under vacuum condition for 1.5 h, although the multilayer structure still was found, part of multilayer interfaces became indistinct and disappeared. In particular, the thickness of the Al-rich layer decreased in contrast to that of as-deposited coating due to the inner diffusion of the Al element. Moreover, the Ti2AlN MAX phase emerged as the major phase in the annealed coatings and its formation mechanism was also discussed in this study. The vacuum thermal analysis indicated that the formed Ti2AlN MAX phase exhibited a high-stability, which was mainly benefited from the large thickness and the dense structure. This advanced technique based on the combined cathodic arc/sputter method could be extended to deposit other MAX phase coatings with tailored high performance like good thermal stability, high corrosion and oxidation resistance etc. for the next protective coating materials.

  11. Polymer Inclusion Membranes with Condensed Phase Membrane Introduction Mass Spectrometry (CP-MIMS): Improved Analytical Response Time and Sensitivity.

    Science.gov (United States)

    Vandergrift, Gregory W; Krogh, Erik T; Gill, Chris G

    2017-05-16

    Condensed phase membrane introduction mass spectrometry (CP-MIMS) is an online, in situ analysis technique for low volatility analytes. Analytes diffuse through a hollow fiber membrane, where they are then dissolved by a liquid (condensed) acceptor phase flowing through the membrane lumen. Permeating analytes are entrained to an atmospheric pressure ionization source for subsequent measurement by a mass spectrometer. Larger analytes, with inherently lower diffusivities, suffer from lengthy response times and lower sensitivity, limiting the use of CP-MIMS for their online, real-time measurement. We present the use of a heptane cosolvent in a methanol acceptor phase in combination with a polydimethylsiloxane (PDMS) membrane. The heptane generates an in situ polymer inclusion membrane (PIM) with the PDMS. We report improved measurement response times and greater sensitivity across a suite of analytes studied (gemfibrozil, nonylphenol, triclosan, 2,4,6-trichlorophenol, and naphthenic acids), with detection limits in the low parts per trillion (ppt) range. These improvements are attributed to increasing analyte diffusivities, as well as increased analyte partitioning across the PIM. Response times are ∼3× faster for the larger analytes studied, and calibration sensitivity is improved by up to ∼3.5× using 0.046 mole fraction heptane in the methanol acceptor. We report the use of short sample exposure times and the use of non-steady-state signals to reduce the analytical duty cycle, and illustrate that the use of a PIM provides a simple and robust variant of CP-MIMS amenable to rapid screening of analytes in complex samples.

  12. Free-cholesterol loading does not trigger phase separation of the fluorescent sterol dehydroergosterol in the plasma membrane of macrophages

    DEFF Research Database (Denmark)

    Wüstner, Daniel

    2008-01-01

    membrane distribution of the fluorescent cholesterol-mimicking sterol dehydroergosterol (DHE) was investigated in FC-loaded J774 macrophages. Wide field fluorescence and deconvolution microscopy were combined with quantitative assessment of sterol distribution in straightened plasma membrane image segments...... with increased membrane cholesterol content, sterols do not form a separate phase in the plasma membrane....

  13. Phase Diagrams and Ordering in Charged Membranes: Binary Mixtures of Charged and Neutral Lipids.

    Science.gov (United States)

    Shimokawa, Naofumi; Himeno, Hiroki; Hamada, Tsutomu; Takagi, Masahiro; Komura, Shigeyuki; Andelman, David

    2016-07-07

    We propose a model describing the phase behavior of two-component membranes consisting of binary mixtures of electrically charged and neutral lipids. We take into account the structural phase transition (main-transition) of the hydrocarbon chains, and investigate the interplay between this phase transition and the lateral phase separation. The presence of charged lipids significantly affects the phase behavior of the multicomponent membrane. Due to the conservation of lipid molecular volume, the main-transition temperature of charged lipids is lower than that of neutral ones. Furthermore, as compared with binary mixtures of neutral lipids, the membrane phase separation in binary mixtures of charged lipids is suppressed, in accord with recent experiments. We distinguish between two types of charged membranes: mixtures of charged saturated lipid/neutral unsaturated lipid and a second case of mixtures of neutral saturated lipid/charged unsaturated lipid. The corresponding phase behavior is calculated and shown to be very different. Finally, we discuss the effect of added salt on the phase separation and the temperature dependence of the lipid molecular area.

  14. Aqueous two-phase partition applied to the isolation of plasma membranes and Golgi apparatus from cultured mammalian cells

    Science.gov (United States)

    Morre, D. M.; Morre, D. J.

    2000-01-01

    Partitioning in dextran-poly(ethylene)glycol (PEG) aqueous-aqueous phase systems represents a mature technology with many applications to separations of cells and to the preparation of membranes from mammalian cells. Most applications to membrane isolation and purification have focused on plasma membranes, plasma membrane domains and separation of right side-out and inside-out plasma membrane vesicles. The method exploits a combination of membrane properties, including charge and hydrophobicity. Purification is based upon differential distributions of the constituents in a sample between the two principal compartments of the two phases (upper and lower) and at the interface. The order of affinity of animal cell membranes for the upper phase is: endoplasmic reticulum Golgi apparatusGolgi apparatus from transformed mammalian cells that combines aqueous two-phase partition and centrifugation. Also described is a periodic NADH oxidase, a new enzyme marker for right side-out plasma membrane vesicles not requiring detergent disruptions for measurement of activity.

  15. Preparation of ultrafiltration membrane by phase separation coupled with microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Suryani, Puput Eka [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. Soedarto, Semarang 50275, Central Java (Indonesia); Department of Chemical Engineering, Faculty of Engineering, UniversitasMuhammadiyah Surakarta Jl. Jendral Ahmad Yani, Surakarta 57102, Central Java (Indonesia); Purnama, Herry [Department of Chemical Engineering, Faculty of Engineering, UniversitasMuhammadiyah Surakarta Jl. Jendral Ahmad Yani, Surakarta 57102, Central Java (Indonesia); Susanto, Heru, E-mail: heru.susanto@undip.ac.id [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. Soedarto, Semarang 50275, Central Java (Indonesia)

    2015-12-29

    Preparation of low fouling ultrafiltration membrane is still a big challenge in the membrane field. In this paper, polyether sulfone (PES) ultrafiltration membranes were prepared by non-solvent-induced phase separation (NIPS) coupled with microwave irradiation. Polyethylene glycol (PEG) and polyethylene glycol methacrylate (PEGMA) were used as additives to improve membrane hydrophilicity. In this study, the concentration of additive, irradiation time and microwave power was varied. The membranes were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, while the performances were tested by adsorptive and ultrafiltration fouling experiments. The results show that the irradiation time and irradiation power are very important parameter that influence the membrane characteristic. In addition, type and concentration of additive are other important parameters. The results suggest that microwave irradiation is the most important parameter influencing the membrane characteristic. Both pure water flux and fouling resistance increase with increasing irradiation time, power irradiation, and additive concentration. PES membrane with addition of 10% w/w PEG and irradiated by 130 W microwave power for 180 seconds is the best membrane performance.

  16. Low concentration of DMSO stabilizes the bilayer gel phase rather than the interdigitated gel phase in dihexadecylphosphatidylcholine membrane.

    Science.gov (United States)

    Yamashita, Y; Kinoshita, K; Yamazaki, M

    2000-08-25

    We have investigated effects of dimethylsulfoxide (DMSO) on the phase stability of multilamellar vesicles of the ether-linked 1,2-dihexadecyl-sn-glycero-3-phosphatidylcholine (DHPC-MLV), which is known to be in the interdigitated gel (LbetaI) phase in excess water at 20 degrees C. The results of X-ray diffraction experiments indicate that the DHPC membrane was in the Lbeta, phase at X> or =0.12 (X=mole fraction of DMSO in DMSO/water mixture). The result of differential scanning calorimetry indicate that the gel to liquid-crystalline phase transition temperature increased, but the LbetaI to Pbeta, phase transition temperature decreased with an increase in DMSO concentration. These results show that DMSO stabilizes the bilayer gel phase rather than the LbetaI phase at its low concentration. The solubility of phosphorylcholine, which is the same structure as the headgroup of DHPC, decreased with an increase in DMSO concentration, indicating that the interaction free energy of the hydrophilic segments of the membrane with solvents increases with an increase in DMSO concentration. On the basis of the thermodynamic analysis, the mechanism of the stabilization of the bilayer gel phase of DHPC-MLV by DMSO is discussed. The decrease in the repulsive interaction between the headgroups of the phospholipid induced by the low concentrations of DMSO in water plays an important role in this stabilization.

  17. NaA Zeolite Membrane with High Performance Synthesized by Vapor Phase Transformation Method

    Institute of Scientific and Technical Information of China (English)

    程志林; 晁自胜; 林海强; 万惠霖

    2003-01-01

    NaA zeolite membrane was synthesized with high permeance on porous alumina substrate by the vapor phase transformation method. The membranes were characterized by XRD and SEM techniques. The XRD results showed that the membranes after the synthesis time of 24 h consisted of the pure NaA zeolite crystals. The SEM results showed that the membranes after the synthesis time of 48 h consisted of intergrown zeolite crystals.The H2 permeance of the NaA zeolite membranes was higher than 2.0 × 10-6 mol/(Pa·m2·s), and the maximum of the gas H2/C3H8 permselectivity was 7.15, which is higher than the corresponding Knudsen diffusion selectivity of which is 4.69.

  18. A novel CO2- and SO2-tolerant dual phase composite membrane for oxygen separation

    DEFF Research Database (Denmark)

    Cheng, Shiyang; Søgaard, Martin; Han, Li;

    2015-01-01

    A novel dual phase composite oxygen membrane (Al0.02Ga0.02Zn0.96O1.02 – Gd0.1Ce0.9O1.95-δ) was successfully prepared and tested. The membrane shows chemical stability against CO2 and SO2, and a stable oxygen permeation over 300 hours in CO2 was demonstrated. ZnO is cheap and non...

  19. Membrane-protein binding measured with solution-phase plasmonic nanocube sensors.

    Science.gov (United States)

    Wu, Hung-Jen; Henzie, Joel; Lin, Wan-Chen; Rhodes, Christopher; Li, Zhu; Sartorel, Elodie; Thorner, Jeremy; Yang, Peidong; Groves, Jay T

    2012-12-01

    We describe a solution-phase sensor of lipid-protein binding based on localized surface plasmon resonance (LSPR) of silver nanocubes. When silica-coated nanocubes are mixed in a suspension of lipid vesicles, supported membranes spontaneously assemble on their surfaces. Using a standard laboratory spectrophotometer, we calibrated the LSPR peak shift due to protein binding to the membrane surface and then characterized the lipid-binding specificity of a pleckstrin homology domain protein.

  20. Role of curvature and phase transition in lipid sorting and fission of membrane tubules

    OpenAIRE

    Roux, Aurélien; Cuvelier, Damien; Nassoy, Pierre; Prost, Jacques; Bassereau, Patricia; Goud, Bruno

    2005-01-01

    We have recently developed a minimal system for generating long tubular nanostructures that resemble tubes observed in vivo with biological membranes. Here, we studied membrane tube pulling in ternary mixtures of sphingomyelin, phosphatidylcholine and cholesterol. Two salient results emerged: the lipid composition is significantly different in the tubes and in the vesicles; tube fission is observed when phase separation is generated in the tubes. This shows that lipid sorting may depend criti...

  1. Study of the effects of different sterilization methods on the properties of dense and porous silk fibroin membranes;Estudo dos efeitos de diferentes metodos de esterilizacao nas propriedades de membranas densas de fibroina de seda

    Energy Technology Data Exchange (ETDEWEB)

    Weska, Raquel F.; Moraes, Mariana A. de; Beppu, Marisa M., E-mail: raquelweska@terra.com.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Quimica

    2009-07-01

    Silk fibroin has been widely explored for many biomedical applications, due to its biocompatibility and biodegradability. Sterilization is a fundamental step in biomaterials processing, and it must not alter in a negative way the functionality of medical devices. The aim of this study was to analyze the influence of different sterilization methods in the physical and chemical characteristics of dense silk fibroin membranes. Dense fibroin membranes were sterilized by ultraviolet radiation, 70% ethanol, autoclave, ethylene oxide and gamma radiation, and were analyzed by SEM, FTIR-ATR and XRD. The results for sterilization indicated that the methods didn't cause degradation of the membranes, but the methods that used organic solvent, or increase of humidity and/or temperature (70% ethanol, autoclave and ethylene oxide) altered the molecular conformation of fibroin, increasing the proportion of beta-sheet structure, what indicates an increase of crystallinity. This effect may be positive when a slower degradation of the membranes is desired, depending on the application as a bio material. (author)

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

    Science.gov (United States)

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

    2002-01-01

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

  3. Rationalization of reduced penetration of drugs through ceramide gel phase membrane.

    Science.gov (United States)

    Paloncýová, Markéta; DeVane, Russell H; Murch, Bruce P; Berka, Karel; Otyepka, Michal

    2014-11-25

    Since computing resources have advanced enough to allow routine molecular simulation studies of drug molecules interacting with biologically relevant membranes, a considerable amount of work has been carried out with fluid phospholipid systems. However, there is very little work in the literature on drug interactions with gel phase lipids. This poses a significant limitation for understanding permeation through the stratum corneum where the primary pathway is expected to be through a highly ordered lipid matrix. To address this point, we analyzed the interactions of p-aminobenzoic acid (PABA) and its ethyl (benzocaine) and butyl (butamben) esters with two membrane bilayers, which differ in their fluidity at ambient conditions. We considered a dioleoylphosphatidylcholine (DOPC) bilayer in a fluid state and a ceramide 2 (CER2, ceramide NS) bilayer in a gel phase. We carried out unbiased (100 ns long) and biased z-constraint molecular dynamics simulations and calculated the free energy profiles of all molecules along the bilayer normal. The free energy profiles converged significantly slower for the gel phase. While the compounds have comparable affinities for both membranes, they exhibit penetration barriers almost 3 times higher in the gel phase CER2 bilayer. This elevated barrier and slower diffusion in the CER2 bilayer, which are caused by the high ordering of CER2 lipid chains, explain the low permeability of the gel phase membranes. We also compared the free energy profiles from MD simulations with those obtained from COSMOmic. This method provided the same trends in behavior for the guest molecules in both bilayers; however, the penetration barriers calculated by COSMOmic did not differ between membranes. In conclusion, we show how membrane fluid properties affect the interaction of drug-like molecules with membranes.

  4. The study of membrane formation via phase inversion method by cloud point and light scattering experiment

    Science.gov (United States)

    Arahman, Nasrul; Maimun, Teuku; Mukramah, Syawaliah

    2017-01-01

    The composition of polymer solution and the methods of membrane preparation determine the solidification process of membrane. The formation of membrane structure prepared via non-solvent induced phase separation (NIPS) method is mostly determined by phase separation process between polymer, solvent, and non-solvent. This paper discusses the phase separation process of polymer solution containing Polyethersulfone (PES), N-methylpirrolidone (NMP), and surfactant Tetronic 1307 (Tet). Cloud point experiment is conducted to determine the amount of non-solvent needed on induced phase separation. Amount of water required as a non-solvent decreases by the addition of surfactant Tet. Kinetics of phase separation for such system is studied by the light scattering measurement. With the addition of Tet., the delayed phase separation is observed and the structure growth rate decreases. Moreover, the morphology of fabricated membrane from those polymer systems is analyzed by scanning electron microscopy (SEM). The images of both systems show the formation of finger-like macrovoids through the cross-section.

  5. Options for laser compression of matter to study dense-plasma phases at low entropy, including metallization of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Meyer-ter-Vehn, J.; Oparin, A. [Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Aoki, T. [Tokyo Institute of Technology, 4259 Nagatsuta, Midori-Ku, Yokohama 227 (Japan)

    1996-05-01

    The potential of high-power lasers for detailed studies of strongly coupled plasmas at low entropy is discussed, emphasizing multiple-shock techniques. Some outstanding features like metallization in solids and related ionization phase transitions in the fluid phase{emdash}predicted theoretically, but not yet observed experimentally{emdash}are reviewed. Planar multiple shock compression of solid hydrogen is described, using reverberating shocks between massive liners and, alternatively, a stepped pressure pulse acting from one side. In the latter case, shock splitting and a rarefaction shock show up at the metallic phase transition. {copyright} {ital 1996 American Institute of Physics.}

  6. Love wave phase velocity models of the southeastern margin of Tibetan Plateau from a dense seismic array

    Science.gov (United States)

    Han, Fengqin; Jia, Ruizhi; Fu, Yuanyuan V.

    2017-08-01

    Love wave dispersion maps across the southeastern margin of the Tibetan Plateau are obtained using earthquake data recorded by the temporary ChinArray and permanent China Digital Seismic Array. Fundamental mode Love wave phase velocity curves are measured by inverting Love wave amplitude and phase with the two-plane-wave method. The phase velocity maps with resolution better than 150 km are presented at periods of 20-100 s, which is unprecedented in the study area. The maps agree well with each other and show clear correlations with major tectonic structures. The Love wave phase velocity could provide new information about structures in the crust and upper mantle beneath the southeast margin of Tibetan Plateau, like the radial anisotropy.

  7. Template-mediated synthesis of periodic membranes for improved liquid-phase separations

    Energy Technology Data Exchange (ETDEWEB)

    Groger, H. [American Research Corp. of Virginia, Radford, VA (United States)

    1997-10-01

    Solid/liquid separations of particulates in waste streams will benefit from design and development of ultrafiltration (UF) membranes with uniform, tailorable pore size and chemical, thermal, and mechanical stability. Such membranes will perform solid/liquid separations with high selectivity, permeance, lifetime, and low operating costs. Existing organic and inorganic membrane materials do not adequately meet all these requirements. An innovative solution to the need for improved inorganic membranes is the application of mesoporous ceramics with narrow pore-size distributions and tailorable pore size (1.5 to 10 nm) that have recently been shown to form with the use of organic surfactant molecules and surfactant assemblies as removable templates. This series of porous ceramics, designated MCM-41, consists of silica or aluminosilicates distinguished by periodic arrays of uniform channels. In this Phase I Small Business Innovation Research program, American Research Corporation of Virginia will demonstrate the use of supported MCM-41 thin films deposited by a proprietary technique, as UF membranes. Technical objectives include deposition in thin, defect-free periodic mesoporous MCM-41 membranes on porous supports; measurement of membrane separation factors, permeance, and fouling; and measurement of membrane lifetime as part of an engineering and economic analysis.

  8. FORMATION AND MICROSTRUCTURE OF POLYETHYLENE MICROPOROUS MEMBRANES THROUGH THERMALLY INDUCED PHASE SEPARATION

    Institute of Scientific and Technical Information of China (English)

    LI Wenjun; YUAN Youxin; CABASSO,Israel

    1995-01-01

    Microporous membranes of low-high density polyethylene and their blends were prepared by thermally-induced phase separation of polymer/long-aliphatic chain alcohol (diluent)mixtures.The microstructures of this particular membrane, which depends on the diluent properties,polymer concentration and cooling rate, were observed by scanning electron microscopy."Beehive-type,"leafy-like, and lacy porous structure morphologies can be formed,depending on the blend composition and phase separation conditions, which were discussed by the polymer and diluent crystallization processes.

  9. Phase coexistence in films composed of DLPC and DPPC: a comparison between different model membrane systems.

    Science.gov (United States)

    Mangiarotti, Agustín; Caruso, Benjamín; Wilke, Natalia

    2014-07-01

    For the biophysical study of membranes, a variety of model systems have been used to measure the different parameters and to extract general principles concerning processes that may occur in cellular membranes. However, there are very few reports in which the results obtained with the different models have been compared. In this investigation, we quantitatively compared the phase coexistence in Langmuir monolayers, freestanding bilayers and supported films composed of a lipid mixture of DLPC and DPPC. Two-phase segregation was observed in most of the systems for a wide range of lipid proportions using fluorescence microscopy. The lipid composition of the coexisting phases was determined and the distribution coefficient of the fluorescent probe in each phase was quantified, in order to explore their thermodynamic properties. The comparison between systems was carried out at 30mN/m, since it is accepted that at this or higher lateral pressures, the mean molecular area in bilayers is equivalent to that observed in monolayers. Our study showed that while Langmuir monolayers and giant unilamellar vesicles had a similar phase behavior, supported films showed a different composition of the phases with the distribution coefficient of the fluorescent probe being close to unity. Our results suggest that, in supported membranes, the presence of the rigid substrate may have led to a stiffening of the liquid-expanded phase due to a loss in the degrees of freedom of the lipids as a consequence of the proximity of the solid material.

  10. Correlated lateral phase separations in stacks of lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Takuma, E-mail: hoshino-takuma@ed.tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978 (Israel); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Komura, Shigeyuki, E-mail: komura@tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Andelman, David, E-mail: andelman@post.tau.ac.il [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978 (Israel); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China)

    2015-12-28

    Motivated by the experimental study of Tayebi et al. [Nat. Mater. 11, 1074 (2012)] on phase separation of stacked multi-component lipid bilayers, we propose a model composed of stacked two-dimensional Ising spins. We study both its static and dynamical features using Monte Carlo simulations with Kawasaki spin exchange dynamics that conserves the order parameter. We show that at thermodynamical equilibrium, due to strong inter-layer correlations, the system forms a continuous columnar structure for any finite interaction across adjacent layers. Furthermore, the phase separation shows a faster dynamics as the inter-layer interaction is increased. This temporal behavior is mainly due to an effective deeper temperature quench because of the larger value of the critical temperature, T{sub c}, for larger inter-layer interaction. When the temperature ratio, T/T{sub c}, is kept fixed, the temporal growth exponent does not increase and even slightly decreases as a function of the increased inter-layer interaction.

  11. Dual phase high-temperature membranes for CO2 separation - performance assessment in post- and pre-combustion processes.

    Science.gov (United States)

    Anantharaman, Rahul; Peters, Thijs; Xing, Wen; Fontaine, Marie-Laure; Bredesen, Rune

    2016-10-20

    Dual phase membranes are highly CO2-selective membranes with an operating temperature above 400 °C. The focus of this work is to quantify the potential of dual phase membranes in pre- and post-combustion CO2 capture processes. The process evaluations show that the dual phase membranes integrated with an NGCC power plant for CO2 capture are not competitive with the MEA process for post-combustion capture. However, dual phase membrane concepts outperform the reference Selexol technology for pre-combustion CO2 capture in an IGCC process. The two processes evaluated in this work, post-combustion NGCC and pre-combustion IGCC, represent extremes in CO2 partial pressure fed to the separation unit. Based on the evaluations it is expected that dual phase membranes could be competitive for post-combustion capture from a pulverized coal fired power plant (PCC) and pre-combustion capture from an Integrated Reforming Cycle (IRCC).

  12. Temperature-dependent phase transitions in zeptoliter volumes of a complex biological membrane

    Energy Technology Data Exchange (ETDEWEB)

    Nikiforov, Maxim P; Jesse, Stephen; Kalinin, Sergei V [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Hohlbauch, Sophia; Proksch, Roger [Asylum Research, Santa Barbara, CA 93117 (United States); King, William P [Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801 (United States); Voitchovsky, Kislon [Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Contera, Sonia Antoranz [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, Oxford (United Kingdom)

    2011-02-04

    Phase transitions in purple membrane have been a topic of debate for the past two decades. In this work we present studies of a reversible transition of purple membrane in the 50-60 deg. C range in zeptoliter volumes under different heating regimes (global heating and local heating). The temperature of the reversible phase transition is 52 {+-} 5 deg. C for both local and global heating, supporting the hypothesis that this transition is mainly due to a structural rearrangement of bR molecules and trimers. To achieve high resolution measurements of temperature-dependent phase transitions, a new scanning probe microscopy-based method was developed. We believe that our new technique can be extended to other biological systems and can contribute to the understanding of inhomogeneous phase transitions in complex systems.

  13. Temperature-dependent phase transitions of a complex biological membrane in zeptoliter volumes

    Energy Technology Data Exchange (ETDEWEB)

    Nikiforov, Maxim [ORNL; Hohlbauch, Sophia [Asylum Research, Santa Barbara, CA; King, William P [University of Illinois, Urbana-Champaign; Voitchovsky, K [Massachusetts Institute of Technology (MIT); Contera, S Antoranz [University of Oxford; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL; Proksch, Roger [Asylum Research, Santa Barbara, CA

    2011-01-01

    Phase transitions in purple membrane have been a topic of debate for the past two decades. In this work we present studies of a reversible transition of purple membrane in the 50 60 C range in zeptoliter volumes under different heating regimes (global heating and local heating). The temperature of the reversible phase transition is 52 5 C for both local and global heating, supporting the hypothesis that this transition is mainly due to a structural rearrangement of bR molecules and trimers. To achieve high resolution measurements of temperature-dependent phase transitions, a new scanning probe microscopy-based method was developed. We believe that our new technique can be extended to other biological systems and can contribute to the understanding of inhomogeneous phase transitions in complex systems.

  14. Observational implications of a strong phase transition in the dense matter equation of state for the rotational evolution of neutron stars

    CERN Document Server

    Bejger, M; Haensel, P; Zdunik, J L; Fortin, M

    2016-01-01

    We explore the implications of a strong first-order phase transition region in the dense matter equation of state in the interiors of rotating neutron stars, and the resulting creation of two disjoint families of neutron-stars' configurations (the so-called high-mass twins). Rotating, axisymmetric and stationary stellar configurations are obtained numerically in the framework of general relativity, and their global parameters and stability are studied. The equation of state-induced instability divides stable neutron star configurations into two disjoint families: neutron stars (second family) and hybrid stars (third family), with an overlapping region in mass, the high-mass twin star region. These two regions are divided by an instability strip. Its existence has interesting astrophysical consequences for rotating neutron stars. We note that it provides a "natural" explanation for the rotational frequency cutoff in the observed distribution of neutron stars spins, and for the apparent lack of back-bending in ...

  15. Yeast lipids can phase separate into micrometer-scale membrane domains

    DEFF Research Database (Denmark)

    Klose, Christian; Ejsing, Christer S; Garcia-Saez, Ana J;

    2010-01-01

    The lipid raft concept proposes that biological membranes have the potential to form functional domains based on a selective interaction between sphingolipids and sterols. These domains seem to be involved in signal transduction and vesicular sorting of proteins and lipids. Although...... there is biochemical evidence for lipid raft-dependent protein and lipid sorting in the yeast Saccharomyces cerevisiae, direct evidence for an interaction between yeast sphingolipids and the yeast sterol ergosterol, resulting in membrane domain formation, is lacking. Here we show that model membranes formed from yeast...... total lipid extracts possess an inherent self-organization potential resulting in Ld-Lo phase coexistence at physiologically relevant temperature. Analyses of lipid extracts from mutants defective in sphingolipid metabolism as well as reconstitution of purified yeast lipids in model membranes of defined...

  16. MICROPOROUS PVDF-HFP-BASED POLYMER MEMBRANES FORMED FROM SUPERCRITICAL CO2 INDUCED PHASE SEPARATION

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Microporous poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)membranes following supercritical CO2 induced phase separation process were prepared using four solvents.The solid electrolytes of PVDF-HFP were formed by microporous PVDF-HFP membranes filled and swollen by a liquid electrolyte.The effect of the solvents on the morphology and structure,electrolyte absorptions and lithium ionic conductivity of the activated membranes were investigated.It was approved that all the membrane had the similar"sponge-like"and asymmetric structure when different solvent was used.As the mutual affinity between solvent and supercritical CO2 decreased,the membrane porosity and the average pore diameter increased.The PVDF-HFP membrane with porosity at 88% and pore size at 10 μm were successfully prepared.The uptake of electrolyte solution and lithium ionic conductivity could reach 487 wt% and 3.09×10-3 S/cm respectively for obtained membrane.

  17. Membrane Active Peptides: Modes-of-Action, Phase Transitions, and Supramolecular Assemblies

    Science.gov (United States)

    Huang, Huey W.

    1997-03-01

    Recent discoveries showed that 20-40 amino-acid peptides are used as very effective antimicrobials in the host-defense systems throughout the animal kingdom, including human. What distinguishes these peptide antimicrobials from the conventional antibiotics is that they attack the lipid matrix of the cytoplasmic membranes rather than protein targets. So the central questions are what are their modes-of-action and how do their distinguish the bacterial cell membranes from the host-cell membranes? Many of these peptides have very simple structures--they are helices with amphiphilic side chains. Despite such simplicities, their interactions with membranes are complex and interesting. The talk will discuss the optical, x-ray and neutron techniques for studying such systems and the experimental as well as theoretical results. The mode-of-action is a phase transition controlled by the concentration of the peptide bound to the membrane. The specificities with respect to membranes are achieved by having different critical concentrations for different lipid composistions of the membrane.

  18. Microstructures in phase-inversion membranes. Part I. Formation of macrovoids

    NARCIS (Netherlands)

    Smolders, C.A.; Smolders, C.A.; Reuvers, A.J.; Reuvers, A.J.; Boom, R.M.; Boom, R.M.; Wienk, I.M.; Wienk, I.M.

    1992-01-01

    A new mechanism for the formation of macrovoids in phase-inversion membranes is proposed. It is based on the observed difference in type of demixing of a thin film of a polymer solution when immersed in a nonsolvent bath: delayed or instantaneous demixing. The explanation for macrovoid formation ass

  19. Membranes Prepared by Self-assembly and Chelation Assisted Phase Inversion

    KAUST Repository

    Xie, Yihui

    2017-05-19

    We combine self-assembly in solution, complexation with metallic salts and phase separation induced by solvent-non-solvent exchange to prepare nanostructured membranes for separation in the nanofiltration range. The method was applied to synthesized poly(acrylic acid)-b-polysulfone-b-poly(acrylic acid) copolymers dissolved in a selective solvent mixture and immersed in aqueous Cu2+ or Ag+ solutions.

  20. A two-scale second-order moment two-phase turbulence model for simulating dense gas-particle flows

    Institute of Scientific and Technical Information of China (English)

    Zhuoxiong Zeng; Lixing Zhou; Jian Zhang; Keren Wang

    2005-01-01

    A two-scale second-order moment two-phase turbulence model accounting for inter-particle collision is developed, based on the concepts of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision and through a unified treatment of these two kinds of fluctuations. The proposed model is used to simulate gas-particle flows in a channel and in a downer. Simulation results are in agreement with the experimental results reported in references and are near the results obtained using the single-scale second-order moment two-phase turbulence model superposed with a particle collision model (USM-θ model)in most regions.

  1. Field assisted sintering of dense Al-substituted cubic phase Li7La3Zr2O12 solid electrolytes

    Science.gov (United States)

    Zhang, Yanhua; Chen, Fei; Tu, Rong; Shen, Qiang; Zhang, Lianmeng

    2014-12-01

    High performance lithium ion conducting Li7La3Zr2O12 solid electrolytes are prepared for the first time by field assisted sintering technology (FAST). The effect of sintering temperature on the phase compositions, microstructure and Li ionic conductivity is systematically investigated. The results show that pure cubic phase LLZO can be obtained at a range of temperatures from 1100 to 1180 °C for no more than 10 min. For the sample sintered at 1150 °C, a maximum relative density of 99.8% with a total ionic conductivity as high as 5.7 × 10-4 S cm-1 are obtained at room temperature. This value is the highest among the present research. Compared with the traditional preparation methods, the current FAST is very promising to obtain high performance LLZO for its advantages of very short sintering time, a single preparation step of reaction-densification processing, and relatively lower sintering temperature.

  2. Preparation and Characterization of Hydrophilically Modified PVDF Membranes by a Novel Nonsolvent Thermally Induced Phase Separation Method

    Directory of Open Access Journals (Sweden)

    Ningen Hu

    2016-11-01

    Full Text Available In this study, a nonsolvent thermally-induced phase separation (NTIPS method was first proposed to fabricate hydrophilically-modified poly(vinylidene fluoride (PVDF membranes to overcome the drawbacks of conventional thermally-induced phase separation (TIPS and nonsolvent-induced phase separation (NIPS methods. Hydrophilically-modified PVDF membranes were successfully prepared by blending in hydrophilic polymer polyvinyl alcohol (PVA at 140 °C. A series of PVDF/PVA blend membranes was prepared at different total polymer concentrations and blend ratios. The morphological analysis via SEM indicated that the formation mechanism of these hydrophilically-modified membranes was a combined NIPS and TIPS process. As the total polymer concentration increased, the tensile strength of the membranes increased; meanwhile, the membrane pore size, porosity and water flux decreased. With the PVDF/PVA blend ratio increased from 10:0 to 8:2, the membrane pore size and water flux increased. The dynamic water contact angle of these membranes showed that the hydrophilic properties of PVDF/PVA blend membranes were prominently improved. The higher hydrophilicity of the membranes resulted in reduced membrane resistance and, hence, higher permeability. The total resistance Rt of the modified PVDF membranes decreased significantly as the hydrophilicity increased. The irreversible fouling related to pore blocking and adsorption fouling onto the membrane surface was minimal, indicating good antifouling properties.

  3. Oxygen permeation in thin, dense Ce0.9Gd0.1O 1.95- membranes I. Model study

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Søgaard, Martin; Hendriksen, Peter Vang

    2011-01-01

    at the feed and permeate side of the membrane, related to the gaseous oxygen reduction and fuel oxidation, respectively, as well as the gas conversion and gas diffusion resistances in the porous support structure at the permeate side. The temperature and oxygen activity dependence of the oxide ionic......A model of a supported planar Ce0.9Gd0.1O 1.95-δ oxygen membrane in a plug-flow setup was constructed and a sensitivity analysis of its performance under varying operating conditions and membrane parameters was performed. The model takes into account the driving force losses at the catalysts...... and electronic conductivity and the oxygen nonstoichiometry of Ce0.9Gd0.1O1.95-δ were described based on literature data. The performance of the membrane was characterised by the delivered oxygen flux and the membrane voltage. The dependence of the performance on the various membrane and operating parameters...

  4. Membraner

    DEFF Research Database (Denmark)

    Bach, Finn

    2009-01-01

    Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner......Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner...

  5. NOVEL INORGANIC MEMBRANES FOR HIGH TEMPERATURE CARBON DIOXIDE SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Jerry Y.S. Lin

    2003-02-01

    We studied feasibility of two types of dense inorganic membranes which are fundamentally different from those porous inorganic membranes reported in the literature for separation of carbon dioxide from gas streams at high temperatures. The first is a symmetric, dense membrane made of Li{sub 2}ZrO{sub 3} and the second is a dual-phase metal-carbonate membrane. We have identified a unique CO{sub 2} sorption/desorption mechanism on lithium zirconate. Considering the all obtained data, we proposed a double layer model to describe the CO{sub 2} sorption/desorption behavior of lithium zirconate. In the model, final product after CO{sub 2} sorption is a particle which consists of a ZrO{sub 2} core inside and a Li{sub 2}CO{sub 3} shell. The understanding of CO{sub 2} sorption mechanisms suggests a means to improve CO{sub 2} sorption rate on this group of oxides. It also leads to the conclusion that lithium zirconate is not a suitable material for the proposed dense ceramic membrane for CO{sub 2} separation. Following the second concept of dense membrane for CO{sub 2} separation, we succeeded in preparing the hermetic (gas-tight) dense inorganic membrane consisting of a porous metal phase and a molten carbonate phase. The metal phase not only provides the mechanical support but also is electronically conducting, reducing the overall mass transfer resistance for CO{sub 2} permeation through the membrane. Permeation data showed that nitrogen or helium is not permeable through these membranes (only CO{sub 2}, with O{sub 2}, can permeate through the membrane based on the transport mechanism). This dual-phase membrane may offer promising properties for applications in membrane processes for separation of CO{sub 2} from flue (or coal gasification gas) at high temperatures (350-550 C).

  6. Distinguishing bicontinuous lipid cubic phases from isotropic membrane morphologies using (31)P solid-state NMR spectroscopy.

    Science.gov (United States)

    Yang, Yu; Yao, Hongwei; Hong, Mei

    2015-04-16

    Nonlamellar lipid membranes are frequently induced by proteins that fuse, bend, and cut membranes. Understanding the mechanism of action of these proteins requires the elucidation of the membrane morphologies that they induce. While hexagonal phases and lamellar phases are readily identified by their characteristic solid-state NMR line shapes, bicontinuous lipid cubic phases are more difficult to discern, since the static NMR spectra of cubic-phase lipids consist of an isotropic (31)P or (2)H peak, indistinguishable from the spectra of isotropic membrane morphologies such as micelles and small vesicles. To date, small-angle X-ray scattering is the only method to identify bicontinuous lipid cubic phases. To explore unique NMR signatures of lipid cubic phases, we first describe the orientation distribution of lipid molecules in cubic phases and simulate the static (31)P chemical shift line shapes of oriented cubic-phase membranes in the limit of slow lateral diffusion. We then show that (31)P T2 relaxation times differ significantly between isotropic micelles and cubic-phase membranes: the latter exhibit 2 orders of magnitude shorter T2 relaxation times. These differences are explained by the different time scales of lipid lateral diffusion on the cubic-phase surface versus the time scales of micelle tumbling. Using this relaxation NMR approach, we investigated a DOPE membrane containing the transmembrane domain (TMD) of a viral fusion protein. The static (31)P spectrum of DOPE shows an isotropic peak, whose T2 relaxation times correspond to that of a cubic phase. Thus, the viral fusion protein TMD induces negative Gaussian curvature, which is an intrinsic characteristic of cubic phases, to the DOPE membrane. This curvature induction has important implications to the mechanism of virus-cell fusion. This study establishes a simple NMR diagnostic probe of lipid cubic phases, which is expected to be useful for studying many protein-induced membrane remodeling phenomena

  7. Roles of Interleaflet Coupling and Hydrophobic Mismatch in Lipid Membrane Phase-Separation Kinetics

    Science.gov (United States)

    2016-01-01

    Characterizing the nanoscale dynamic organization within lipid bilayer membranes is central to our understanding of cell membranes at a molecular level. We investigate phase separation and communication across leaflets in ternary lipid bilayers, including saturated lipids with between 12 and 20 carbons per tail. Coarse-grained molecular dynamics simulations reveal a novel two-step kinetics due to hydrophobic mismatch, in which the initial response of the apposed leaflets upon quenching is to increase local asymmetry (antiregistration), followed by dominance of symmetry (registration) as the bilayer equilibrates. Antiregistration can become thermodynamically preferred if domain size is restricted below ∼20 nm, with implications for the symmetry of rafts and nanoclusters in cell membranes, which have similar reported sizes. We relate our findings to theory derived from a semimicroscopic model in which the leaflets experience a “direct” area-dependent coupling, and an “indirect” coupling that arises from hydrophobic mismatch and is most important at domain boundaries. Registered phases differ in composition from antiregistered phases, consistent with a direct coupling between the leaflets. Increased hydrophobic mismatch purifies the phases, suggesting that it contributes to the molecule-level lipid immiscibility. Our results demonstrate an interplay of competing interleaflet couplings that affect phase compositions and kinetics, and lead to a length scale that can influence lateral and transverse bilayer organization within cells. PMID:27574865

  8. Controlled in meso phase crystallization--a method for the structural investigation of membrane proteins.

    Directory of Open Access Journals (Sweden)

    Jan Kubicek

    Full Text Available We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i the stabilization of membrane proteins in the meso phase, (ii the control of hydration level and additive concentration by vapor diffusion. The new technology (iii significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII from Halobacterium salinarum for the first time.

  9. Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide

    DEFF Research Database (Denmark)

    Musko, Nikolai; Jensen, Anker Degn; Baiker, Alfons

    2012-01-01

    vapour–liquid or liquid–liquid equilibria data available in the literature. No experimental data for the CO2–2-butenal binary system were available in the literature; therefore, the bubble points of this mixture of varying composition at three different temperatures were measured in a high-pressure view...... cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO2 the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved...... in the so-called “expanded liquid” region, which is located near the critical point of the reacting mixture. It was also found that in this point the hydrogen concentration achieved its maximum in the CO2-expanded phase. Furthermore, the pressure – temperature regions where the multicomponent reaction...

  10. A mixed ionic and electronic conducting dual-phase membrane with high oxygen permeability.

    Science.gov (United States)

    Fang, Wei; Liang, Fangyi; Cao, Zhengwen; Steinbach, Frank; Feldhoff, Armin

    2015-04-13

    To combine good chemical stability and high oxygen permeability, a mixed ionic-electronic conducting (MIEC) 75 wt% Ce(0.85)Gd(0.1)Cu(0.05)O(2-δ)-25 wt% La(0.6)Ca(0.4)FeO(3-δ)(CGCO-LCF) dual-phase membrane based on a MIEC-MIEC composite has been developed. Copper doping into Ce(0.9)Gd(0.1)O(2-δ) (CGO) oxide enhances both ionic and electronic conductivity, which then leads to a change from ionic conduction to mixed conduction at elevated temperatures. For the first time we demonstrate that an intergranular film with 2-10 nm thickness containing Ce, Ca, Gd, La, and Fe has been formed between the CGCO grains in the CGCO-LCF one-pot dual-phase membrane. A high oxygen permeation flux of 0.70 mL min(-1) cm(-2) is obtained by the CGCO-LCF one-pot dual-phase membrane with 0.5 mm thickness at 950 °C using pure CO2 as the sweep gas, and the membrane shows excellent stability in the presence of CO2 even at lower temperatures (800 °C) during long-term operation.

  11. Sterol structure determines the separation of phases and the curvature of the liquid-ordered phase in model membranes.

    Science.gov (United States)

    Bacia, Kirsten; Schwille, Petra; Kurzchalia, Teymuras

    2005-03-01

    The existence of lipid rafts in biological membranes in vivo is still debated. In contrast, the formation of domains in model systems has been well documented. In giant unilamellar vesicles (GUVs) prepared from ternary mixtures of dioleoyl-phosphatidylcholine/sphingomyelin/cholesterol, a clear separation of liquid-disordered and sphingomyelin-enriched, liquid-ordered phases could be observed. This phase separation can lead to the fission of the liquid-ordered phase from the vesicle. Here we show that in cholesterol-containing GUVs, the phase separation can involve dynamic redistribution of lipids from one phase into another as a result of a cross-linking perturbation. We found that the molecular structure of a sterol used for the preparation of GUVs determines (i) its ability to induce phase separation and (ii) the curvature (positive or negative) of the formed liquid-ordered phase. As a consequence, the latter can pinch off to the outside or inside of the vesicle. Remarkably, some mixtures of sterols induce liquid-ordered domains exhibiting both positive and negative curvature, which can lead to a new type of budding behavior in GUVs. Our findings could have implications for the role of sterols in various cell-biological processes such as budding of secretory vesicles, endocytosis, or formation of multivesicular bodies.

  12. Thermotropic phase transitions in model membranes of the outer skin layer based on ceramide 6

    Science.gov (United States)

    Gruzinov, A. Yu.; Kiselev, M. A.; Ermakova, E. V.; Zabelin, A. V.

    2014-01-01

    The lipid intercellular matrix stratum corneum of the outer skin layer is a multilayer membrane consisting of a complex mixture of different lipids: ceramides, fatty acids, cholesterol, and its derivatives. The basis of the multilayer membrane is the lipid bilayer, i.e., a two-dimensional liquid crystal. Currently, it is known that the main way of substance penetration through the skin is the lipid matrix. The complexity of the actual biological system does not allow reliable direct study of its properties; therefore, system modeling is often used. Phase transitions in the lipid system whose composition simulates the native lipid matrix are studied by the X-ray synchrotron radiation diffraction method.

  13. Structure and properties of PVDF membrane with PES-C addition via thermally induced phase separation process

    Science.gov (United States)

    Wu, Lishun; Sun, Junfen

    2014-12-01

    Polyvinylidene fluoride (PVDF) membrane and PVDF membrane with phenolphthalein polyethersulfone (PES-C) addition were prepared via thermally induced phase separation (TIPS) method by using diphenyl carbonate (DPC) and dimethyl acetamide (DMAc) as mixed diluents. The effects of coagulation temperature and pre-evaporation time on structure and properties of membranes were studied. The changes of sewage flux in MBR and the attenuation coefficient of sewage flux were investigated. The resistance distributions of PVDF and PVDF/PES-C membranes were compared by resistance analysis. Membrane composition and structure were characterized by ATR-FTIR, TGA, SEM and AFM. The foulant on membranes was analyzed by FTIR. The contact angle of PVDF/PES-C membrane was lower than that of PVDF membrane. A thinner skin layer and a porous cellular support layer formed in PVDF/PES-C membrane and resulted in a higher porosity and pure water flux. The pure water flux and porosity of PVDF/PES-C membrane increased with rising coagulation temperature and decreased with extending pre-evaporation time. The flux attenuation coefficient, the cake layer resistance and internal fouling resistance of PVDF/PES-C membrane in MBR were smaller than those of PVDF membrane in MBR. The FTIR spectrum of foulant on membrane indicated that the foulant on PVDF/PES-C membrane was mostly composed of protein and polysaccharide, while the foulant on pure PVDF membrane included biopolymer clusters besides protein and polysaccharide.

  14. Growth Conditions and Cell Cycle Phase Modulate Phase Transition Temperatures in RBL-2H3 Derived Plasma Membrane Vesicles.

    Directory of Open Access Journals (Sweden)

    Erin M Gray

    Full Text Available Giant plasma membrane vesicle (GPMV isolated from a flask of RBL-2H3 cells appear uniform at physiological temperatures and contain coexisting liquid-ordered and liquid-disordered phases at low temperatures. While a single GPMV transitions between these two states at a well-defined temperature, there is significant vesicle-to-vesicle heterogeneity in a single preparation of cells, and average transition temperatures can vary significantly between preparations. In this study, we explore how GPMV transition temperatures depend on growth conditions, and find that average transition temperatures are negatively correlated with average cell density over 15°C in transition temperature and nearly three orders of magnitude in average surface density. In addition, average transition temperatures are reduced by close to 10°C when GPMVs are isolated from cells starved of serum overnight, and elevated transition temperatures are restored when serum-starved cells are incubated in serum-containing media for 12 h. We also investigated variation in transition temperature of GPMVs isolated from cells synchronized at the G1/S border through a double Thymidine block and find that average transition temperatures are systematically higher in GPMVs produced from G1 or M phase cells than in GPMVs prepared from S or G1 phase cells. Reduced miscibility transition temperatures are also observed in GPMVs prepared from cells treated with TRAIL to induce apoptosis or sphingomyelinase, and in some cases a gel phase is observed at temperatures above the miscibility transition in these vesicles. We conclude that at least some variability in GPMV transition temperature arises from variation in the local density of cells and asynchrony of the cell cycle. It is hypothesized that GPMV transition temperatures are a proxy for the magnitude of lipid-mediated membrane heterogeneity in intact cell plasma membranes at growth temperatures. If so, these results suggest that cells tune

  15. Effect of soil moisture dynamics on dense nonaqueous phase liquid (DNAPL) spill zone architecture in heterogeneous porous media.

    Science.gov (United States)

    Yoon, Hongkyu; Valocchi, Albert J; Werth, Charles J

    2007-03-20

    The amount, location, and form of NAPL in contaminated vadose zones are controlled by the spatial distribution of water saturation and soil permeability, the NAPL spill scenario, water infiltration events, and vapor transport. To evaluate the effects of these processes, we used the three-phase flow simulator STOMP, which includes a new permeability-liquid saturation-capillary pressure (k-S-P) constitutive model. This new constitutive model considers three NAPL forms: free, residual, and trapped. A 2-D vertical cross-section with five stratigraphic layers was assumed, and simulations were performed for seven cases. The conceptual model of the soil heterogeneity was based upon the stratigraphy at the Hanford carbon tetrachloride (CT) spill site. Some cases considered co-disposal of NAPL with large volumes of wastewater, as also occurred at the Hanford CT site. In these cases, the form and location of NAPL were most strongly influenced by high water discharge rates and NAPL evaporation to the atmosphere. In order to investigate the impact of heterogeneity, the hydraulic conductivity within the lower permeability layer was modeled as a realization of a random field having three different classes. For six extreme cases of 100 realizations, the CT mass that reached the water table varied by a factor of two, and was primarily controlled by the degree of lateral connectivity of the low conductivity class within the lowest permeability layer. The grid size at the top boundary had a dramatic impact on NAPL diffusive flux just after the spill event when the NAPL was present near the ground surface. NAPL evaporation with a fine grid spacing at the top boundary decreased CT mass that reached the water table by 74%, compared to the case with a coarse grid spacing, while barometric pumping had a marginal effect for the case of a continuous NAPL spill scenario considered in this work. For low water infiltration rate scenarios, the distribution of water content prior to a NAPL

  16. Live cell plasma membranes do not exhibit a miscibility phase transition over a wide range of temperatures.

    Science.gov (United States)

    Lee, Il-Hyung; Saha, Suvrajit; Polley, Anirban; Huang, Hector; Mayor, Satyajit; Rao, Madan; Groves, Jay T

    2015-03-26

    Lipid/cholesterol mixtures derived from cell membranes as well as their synthetic reconstitutions exhibit well-defined miscibility phase transitions and critical phenomena near physiological temperatures. This suggests that lipid/cholesterol-mediated phase separation plays a role in the organization of live cell membranes. However, macroscopic lipid-phase separation is not generally observed in cell membranes, and the degree to which properties of isolated lipid mixtures are preserved in the cell membrane remain unknown. A fundamental property of phase transitions is that the variation of tagged particle diffusion with temperature exhibits an abrupt change as the system passes through the transition, even when the two phases are distributed in a nanometer-scale emulsion. We support this using a variety of Monte Carlo and atomistic simulations on model lipid membrane systems. However, temperature-dependent fluorescence correlation spectroscopy of labeled lipids and membrane-anchored proteins in live cell membranes shows a consistently smooth increase in the diffusion coefficient as a function of temperature. We find no evidence of a discrete miscibility phase transition throughout a wide range of temperatures: 14-37 °C. This contrasts the behavior of giant plasma membrane vesicles (GPMVs) blebbed from the same cells, which do exhibit phase transitions and macroscopic phase separation. Fluorescence lifetime analysis of a DiI probe in both cases reveals a significant environmental difference between the live cell and the GPMV. Taken together, these data suggest the live cell membrane may avoid the miscibility phase transition inherent to its lipid constituents by actively regulating physical parameters, such as tension, in the membrane.

  17. Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes.

    Science.gov (United States)

    Santhosh, Poornima Budime; Drašler, Barbara; Drobne, Damjana; Kreft, Mateja Erdani; Kralj, Slavko; Makovec, Darko; Ulrih, Nataša Poklar

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to bê11 nm), silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm). Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a slightly increased effect on the fluidity of the model membranes in comparison with the incubated SPIONs. This indicates the low potential of the SPIONs to interact with the nontargeted cell membranes, which is a desirable factor for in vivo applications.

  18. "Reagentless" flow injection determination of ammonia and urea using membrane separation and solid phase basification

    Science.gov (United States)

    Akse, J. R.; Thompson, J. O.; Sauer, R. L.; Atwater, J. E.

    1998-01-01

    Flow injection analysis instrumentation and methodology for the determination of ammonia and ammonium ions in an aqueous solution are described. Using in-line solid phase basification beds containing crystalline media. the speciation of ammoniacal nitrogen is shifted toward the un-ionized form. which diffuses in the gas phase across a hydrophobic microporous hollow fiber membrane into a pure-water-containing analytical stream. The two streams flow in a countercurrent configuration on opposite sides of the membrane. The neutral pH of the analytical stream promotes the formation of ammonium cations, which are detected using specific conductance. The methodology provides a lower limit of detection of 10 microgram/L and a dynamic concentration range spanning three orders of magnitude using a 315-microliters sample injection volume. Using immobilized urease to enzymatically promote the hydrolysis of urea to produce ammonia and carbon dioxide, the technique has been extended to the determination of urea.

  19. Phase-inversion tape casting and oxygen permeation properties of supported ceramic membranes

    NARCIS (Netherlands)

    He, Wei; Huang, Hua; Gao, Jianfeng; Winnubst, A.J.A.; Chen, Chusheng

    2014-01-01

    A variant of tape casting, involving phase inversion, was explored for the preparation of supported ceramic oxygen separation membranes in one step. A slurry of Zr0.84Y0.16O1.92 (YSZ) andLa0.8Sr0.2MnO3 δ (LSM) powders in a N-methyl-2-pyrrolidone solution of polyethersulfone was tape cast, and immers

  20. In-line and selective phase separation of medium-chain carboxylic acids using membrane electrolysis.

    Science.gov (United States)

    Xu, Jiajie; Guzman, Juan J L; Andersen, Stephen J; Rabaey, Korneel; Angenent, Largus T

    2015-04-21

    We had extracted n-caproate from bioreactor broth. Here, we introduced in-line membrane electrolysis that utilized a pH gradient between two chambers to transfer the product into undissociated n-caproic acid without chemical addition. Due to the low maximum solubility of this acid, selective phase separation occurred, allowing simple product separation into an oily liquid containing ∼90% n-caproic and n-caprylic acid.

  1. PREPARATION OF ZINC OXIDE AND POLY-ETHYLENE OXIDE COMPOSITE MEMBRANES AND THEIR PHASE RELATIONSHIP

    OpenAIRE

    JESÚS FABIAN JURADO; CARLOS VARGAS HERNÁNDEZ; RUBÉN ANTONIO VARGAS

    2012-01-01

    Zinc oxide and organic polymer (poly-ethylene oxide) based nanocomposite membranes were prepared and their phase relationship investigated. The composites were characterized by XRD, Raman scattering, DSC, and impedance spectroscopy analysis. It was found that embedding inorganic nanoparticles of ZnO into the polymer matrix of PEO allowed for some crystallinity formation, and cross-linking of the polymer composites during annealing or synthesis. The XRD and Raman scattering results show more d...

  2. Energetics of the Phase Transition in Free-Standing versus Supported Lipid Membranes.

    Science.gov (United States)

    Mangiarotti, Agustín; Wilke, Natalia

    2015-07-16

    We compared the thermodynamic behavior of supported and free-standing films of phospholipids with different chain length and showed that the change in free energy for the phase transition to a denser state was greater in free-standing than in supported membranes, with the differences being independent of the chain length. The presence of the support promoted a decrease in the energy gap between the coexisting phases of 1.7 kJ mol(-1), and this was a long-range effect affecting both leaflets, probably related with the impediment of out-of-plane motion of the film by the solid surface.

  3. Threshold for spontaneous oscillation in a three-phase liquid membrane system involving nonionic surfactant.

    Science.gov (United States)

    Nanzai, Ben; Funazaki, Tomohisa; Igawa, Manabu

    2010-09-16

    This study of self-oscillation was conducted using a new three-phase liquid membrane system of ethanol aqueous solution, benzyl alcohol solution with nonionic surfactant, and pure water. Relations of the initial ethanol concentration to the oscillation amplitude and frequency, and to the induction period before oscillations were investigated. The oscillation amplitude is independent of the initial ethanol concentration, but the frequency and the induction period are related to it. The oscillation frequency increased concomitantly with the increased ethanol initial concentration, but the induction period before the electrical oscillations decreased with increasing concentration. To estimate the influence of ethanol diffusion on the electrical oscillations, the ethanol concentration in each phase was measured using separate experiments after different durations of oscillation. The diffusion coefficient was calculated using Fick's second law. Results show successful estimation of the threshold for oscillations. The threshold is defined in terms of the ethanol concentration at the interface between the benzyl alcohol phase and the pure water phase.

  4. Aqueous two-phase partition applied to the isolation of plasma membranes and Golgi apparatus from cultured mammalian cells

    Science.gov (United States)

    Morre, D. M.; Morre, D. J.

    2000-01-01

    Partitioning in dextran-poly(ethylene)glycol (PEG) aqueous-aqueous phase systems represents a mature technology with many applications to separations of cells and to the preparation of membranes from mammalian cells. Most applications to membrane isolation and purification have focused on plasma membranes, plasma membrane domains and separation of right side-out and inside-out plasma membrane vesicles. The method exploits a combination of membrane properties, including charge and hydrophobicity. Purification is based upon differential distributions of the constituents in a sample between the two principal compartments of the two phases (upper and lower) and at the interface. The order of affinity of animal cell membranes for the upper phase is: endoplasmic reticulum two-phase partition with other procedures to obtain a more highly purified preparation. A procedure is described for preparation of Golgi apparatus from transformed mammalian cells that combines aqueous two-phase partition and centrifugation. Also described is a periodic NADH oxidase, a new enzyme marker for right side-out plasma membrane vesicles not requiring detergent disruptions for measurement of activity.

  5. Warm gas phase chemistry as possible origin of high HDO/H2O ratios in hot and dense gases: application to inner protoplanetary discs

    CERN Document Server

    Thi, Wing-Fai; Kamp, Inga

    2009-01-01

    The origin of Earth oceans is controversial. Earth could have acquired its water either from hydrated silicates (wet Earth scenario) or from comets (dry Earth scenario). [HDO]/[H2O] ratios are used to discriminate between the scenarios. High [HDO]/[H2O] ratios are found in Earth oceans. These high ratios are often attributed to the release of deuterium enriched cometary water ice, which was formed at low gas and dust temperatures. Observations do not show high [HDO]/[H2O] in interstellar ices. We investigate the possible formation of high [HDO]/[H2O] ratios in dense (nH> 1E6 cm^{-3}) and warm gas (T=100-1000 K) by gas-phase photochemistry in the absence of grain surface chemistry. We derive analytical solutions, taking into account the major neutral-neutral reactions for gases at T>100 K. The chemical network is dominated by photodissociation and neutral-neutral reactions. Despite the high gas temperature, deuterium fractionation occurs because of the difference in activation energy between deuteration enrich...

  6. Motile Geobacter dechlorinators migrate into a model source zone of trichloroethene dense non-aqueous phase liquid: Experimental evaluation and modeling

    Science.gov (United States)

    Philips, Jo; Miroshnikov, Alexey; Haest, Pieter Jan; Springael, Dirk; Smolders, Erik

    2014-12-01

    Microbial migration towards a trichloroethene (TCE) dense non-aqueous phase liquid (DNAPL) could facilitate the bioaugmentation of TCE DNAPL source zones. This study characterized the motility of the Geobacter dechlorinators in a TCE to cis-dichloroethene dechlorinating KB-1™ subculture. No chemotaxis towards or away from TCE was found using an agarose in-plug bridge method. A second experiment placed an inoculated aqueous layer on top of a sterile sand layer and showed that Geobacter migrated several centimeters in the sand layer in just 7 days. A random motility coefficient for Geobacter in water of 0.24 ± 0.02 cm2·day- 1 was fitted. A third experiment used a diffusion-cell setup with a 5.5 cm central sand layer separating a DNAPL from an aqueous top layer as a model source zone to examine the effect of random motility on TCE DNAPL dissolution. With top layer inoculation, Geobacter quickly colonized the sand layer, thereby enhancing the initial TCE DNAPL dissolution flux. After 19 days, the DNAPL dissolution enhancement was only 24% lower than with an homogenous inoculation of the sand layer. A diffusion-motility model was developed to describe dechlorination and migration in the diffusion-cells. This model suggested that the fast colonization of the sand layer by Geobacter was due to the combination of random motility and growth on TCE.

  7. Extraction of yeast mitochondrial membrane proteins by solubilization and detergent/polymer aqueous two-phase partitioning.

    Science.gov (United States)

    Everberg, Henrik; Gustavsson, Niklas; Tjerneld, Folke

    2009-01-01

    Identification and characterization of membrane proteins is of increasing importance in modern proteomic studies. It is of central interest to have access to methods that combine efficient solubilization with enrichment of proteins and intact protein complexes. Separation methods have been developed based on nondenaturing detergent extraction of yeast mitochondrial membrane proteins followed by enrichment of hydrophobic proteins in aqueous two-phase system. Combining the zwitterionic detergent Zwittergent 3-10 and the nonionic detergent Triton X-114 results in a complementary solubilization of proteins, which is similar to that of the anionic detergent sodium dodecyl sulfate (SDS) but with the important advantage of being nondenaturing. Detergent/polymer two-phase system partitioning offers removal of soluble proteins, which can be further improved by manipulation of the driving forces governing protein distribution between the phases. Integral and peripheral membrane protein subunits from intact membrane protein complexes partition to the detergent phase while soluble proteins are found in the polymer phase. A protocol is presented which combines nondenaturing solubilization of membrane proteins with extraction in detergent/polymer two-phase system for application in proteomic studies as a mild and efficient method for enrichment of membrane proteins and membrane protein complexes.

  8. Dense-cored vesicles, smooth endoplasmic reticulum, and mitochondria are closely associated with non-specialized parts of plasma membrane of nerve terminals: implications for exocytosis and calcium buffering by intraterminal organelles.

    Science.gov (United States)

    Lysakowski, A; Figueras, H; Price, S D; Peng, Y Y

    1999-01-18

    To determine whether there are anatomical correlates for intraterminal Ca2+ stores to regulate exocytosis of dense-cored vesicles (DCVs) and whether these stores can modulate exocytosis of synaptic vesicles, we studied the spatial distributions of DCVs, smooth endoplasmic reticulum (SER), and mitochondria in 19 serially reconstructed nerve terminals in bullfrog sympathetic ganglia. On average, each bouton had three active zones, 214 DCVs, 26 SER fragments (SERFs), and eight mitochondria. DCVs, SERFs and mitochondria were located, on average, 690, 624, and 526 nm, respectively, away from active zones. Virtually no DCVs were within "docking" (i.e., similar to those for exocytosis of synaptic vesicles. Because there were virtually no SERFs or mitochondria within 50 nm of any active zone, Ca2+ modulation by these organelles is unlikely to affect ACh release evoked by a single action potential. In contrast, 30% of DCVs and 40% of SERFs were located within 50 nm of the nonspecialized regions of the plasma membrane. Because each bouton had at least one SERF within 50 nm of the plasma membrane and most of these SERFs had DCVs, but not mitochondria, near them, it is possible for Ca2+ release from the SER to provide the Ca2+ necessary for DCV exocytosis. The fact that 60% of the mitochondria had some part within 50 nm of the plasma membrane means that it is possible for mitochondrial Ca2+ buffering to affect DCV exocytosis.

  9. Treatment of phenol in synthetic saline wastewater by solvent extraction and two-phase membrane biodegradation.

    Science.gov (United States)

    Juang, Ruey-Shin; Huang, Wen-Ching; Hsu, Ya-Han

    2009-05-15

    Phenol in synthetic saline (100gL(-1) NaCl) and acidic (pH 3) wastewater was treated by a hybrid solvent extraction and two-phase membrane biodegradation process at 30 degrees C. Kerosene was adopted to be the organic solvent because it was biocompatible and had a suitable partition coefficient for phenol. Phenol in water was first extracted by kerosene in a batch stirred vessel and the loaded solvent was passed through the lumen of a polyvinylidene fluoride (PVDF) hollow-fiber membrane contactor; in the meantime, Pseudomonas putida BCRC 14365 in mineral salt medium was flowed across the shell, to which tetrasodium phyophosphate (1gL(-1)) was added as a dispersing agent. The effect of the initial phenol level in wastewater (110-2400mgL(-1)) on phenol removal and cell growth was experimentally studied. At a cell concentration of 0.023gL(-1), it was shown that the removal of phenol from saline wastewater was more efficient at a level of 2000mgL(-1) when 0.02-m(2) membrane module was used. The effects of bigger membrane module size (0.19m(2) area) and higher initial cell concentration (0.092-0.23gL(-1)) on the performance of such a hybrid process for the treatment of higher-level phenol in saline wastewater was also evaluated and discussed.

  10. Reactive phase inversion for manufacture of asymmetric poly (ether imide sulfone) membranes

    KAUST Repository

    Jalal, Taghreed

    2014-12-01

    Poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine) or TiO2 nanoparticles. Polysilsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. The membranes were characterized by field emission scanning electron microscopy, porosimetry and water flux measurements. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, which allowed 99.2% rejection of γ-globulin. Water flux recovery of 77.5% was achieved after filtration with proteins. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100% tetrahydrofuran. The possibility of using similar concept for homogeneous and stable attachment of nanoparticles on the membrane surface was demonstrated.

  11. Isoporous PS-b-PEO ultrafiltration membranes via self-assembly and water-induced phase separation

    KAUST Repository

    Karunakaran, Madhavan

    2014-03-01

    A simple and efficient approach towards the fabrication of a skinned membrane with highly ordered pores in the nanometer range is presented here. We successfully combined the self-assembly of PS-b-PEO block copolymer and water induced phase separation for the preparation of isoporous PS-b-PEO block copolymer membranes. We produced for the first time asymmetric isoporous PS-b-PEO membranes with a 100nm thin isoporous separating layer using water at room temperature as coagulant. This was possible by careful selection of the block lengths and the solvent system. FESEM, AFM and TEM measurements were employed to characterize the nanopores of membranes. The pure water fluxes were measured and the flux of membrane was exceptionally high (around 800Lm-2h-1bar-1). Protein rejection measurements were carried out for this membrane and the membrane had a retention of about 67% of BSA and 99% of γ-globulin. © 2013 Elsevier B.V.

  12. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...... for the lateral organization of membranes as wells as for physical properties like bending, permeability and elasticity...

  13. Conductive dense hydrogen

    Science.gov (United States)

    Eremets, M.; Troyan, I.

    2012-12-01

    Hydrogen at ambient pressures and low temperatures forms a molecular crystal which is expected to display metallic properties under megabar pressures. This metal is predicted to be superconducting with a very high critical temperature Tc of 200-400 K. The superconductor may potentially be recovered metastably at ambient pressures, and it may acquire a new quantum state as a metallic superfluid and a superconducting superfluid. Recent experiments performed at low temperatures T 220 GPa, new Raman modes arose, providing evidence for the transformation to a new opaque and electrically conductive phase IV. Above 260 GPa, in the next phase V, hydrogen reflected light well. Its resistance was nearly temperature-independent over a wide temperature range, down to 30 K, indicating that the hydrogen was metallic. Releasing the pressure induced the metallic phase to transform directly into molecular hydrogen with significant hysteresis at 200 GPa and 295 K. These data were published in our paper: M. I. Eremets and I. A. Troyan "Conductive dense hydrogen." Nature Materials 10: 927-931. We will present also new results on hydrogen: phase diagram with phases IV and V determined in P,T domain up to 300 GPa and 350 K. We will also discuss possible structures of phase IV based on our Raman and infrared measurements up to 300 GPa.

  14. Biomolecule-recognition gating membrane using biomolecular cross-linking and polymer phase transition.

    Science.gov (United States)

    Kuroki, Hidenori; Ito, Taichi; Ohashi, Hidenori; Tamaki, Takanori; Yamaguchi, Takeo

    2011-12-15

    We present for the first time a biomolecule-recognition gating system that responds to small signals of biomolecules by the cooperation of biorecognition cross-linking and polymer phase transition in nanosized pores. The biomolecule-recognition gating membrane immobilizes the stimuli-responsive polymer, including the biomolecule-recognition receptor, onto the pore surface of a porous membrane. The pore state (open/closed) of this gating membrane depends on the formation of specific biorecognition cross-linking in the pores: a specific biomolecule having multibinding sites can be recognized by several receptors and acts as the cross-linker of the grafted polymer, whereas a nonspecific molecule cannot. The pore state can be distinguished by a volume phase transition of the grafted polymer. In the present study, the principle of the proposed system is demonstrated using poly(N-isopropylacrylamide) as the stimuli-responsive polymer and avidin-biotin as a multibindable biomolecule-specific receptor. As a result of the selective response to the specific biomolecule, a clear permeability change of an order of magnitude was achieved. The principle is versatile and can be applied to many combinations of multibindable analyte-specific receptors, including antibody-antigen and lectin-sugar analogues. The new gating system can find wide application in the bioanalytical field and aid the design of novel biodevices.

  15. Porous Polyimide Membranes Prepared by Wet Phase Inversion for Use in Low Dielectric Applications

    Directory of Open Access Journals (Sweden)

    Jung Ah Lim

    2013-04-01

    Full Text Available A wet phase inversion process of polyamic acid (PAA allowed fabrication of a porous membrane of polyimide (PI with the combination of a low dielectric constant (1.7 and reasonable mechanical properties (Tensile strain: 8.04%, toughness: 3.4 MJ/m3, tensile stress: 39.17 MPa, and young modulus: 1.13 GPa, with further thermal imidization process of PAA. PAA was simply synthesized from purified pyromellitic dianhydride (PMDA and 4,4-oxydianiline (ODA in two different reaction solvents such as γ-butyrolactone (GBL and N-methyl-2-pyrrolidinone (NMP, which produce Mw/PDI of 630,000/1.45 and 280,000/2.0, respectively. The porous PAA membrane was fabricated by the wet phase inversion process based on a solvent/non-solvent system via tailored composition between GBL and NMP. The porosity of PI, indicative of a low electric constant, decreased with increasing concentration of GBL, which was caused by sponge-like formation. However, due to interplay between the low electric constant (structural formation and the mechanical properties, GBL was employed for further exploration, using toluene and acetone vs. DI-water as a coagulation media. Non-solvents influenced determination of the PAA membrane size and porosity. With this approach, insight into the interplay between dielectric properties and mechanical properties will inform a wide range of potential low-k material applications.

  16. Membrane-less micro fuel cell based on two-phase flow

    Science.gov (United States)

    Hashemi, S. M. H.; Neuenschwander, M.; Hadikhani, P.; Modestino, M. A.; Psaltis, D.

    2017-04-01

    Most microfluidic fuel cells use highly soluble fuels and oxidants in streams of liquid electrolytes to overcome the mass transport limitations that result from the low solubility of gaseous reactants such as hydrogen and oxygen. In this work, we address these limitations by implementing controlled two-phase flows of these gases in a set of microchannels electrolytically connected through a narrow gap. Annular flows of the gases reshape the concentration boundary layer over the surface of electrodes and increase the mass-transport limited current density in the system. Our results show that the power density of a two-phase system with hydrogen and oxygen streams is an order of magnitude higher than that of single phase system consisting of liquid electrolytes saturated with the same reactants. The reactor design described here can be employed to boost the performance of MFFCs and put them in a more competitive position compared to membrane based fuel cells.

  17. Warm dense crystallography

    Science.gov (United States)

    Valenza, Ryan A.; Seidler, Gerald T.

    2016-03-01

    The intense femtosecond-scale pulses from x-ray free electron lasers (XFELs) are able to create and interrogate interesting states of matter characterized by long-lived nonequilibrium semicore or core electron occupancies or by the heating of dense phases via the relaxation cascade initiated by the photoelectric effect. We address here the latter case of "warm dense matter" (WDM) and investigate the observable consequences of x-ray heating of the electronic degrees of freedom in crystalline systems. We report temperature-dependent density functional theory calculations for the x-ray diffraction from crystalline LiF, graphite, diamond, and Be. We find testable, strong signatures of condensed-phase effects that emphasize the importance of wide-angle scattering to study nonequilibrium states. These results also suggest that the reorganization of the valence electron density at eV-scale temperatures presents a confounding factor to achieving atomic resolution in macromolecular serial femtosecond crystallography (SFX) studies at XFELs, as performed under the "diffract before destroy" paradigm.

  18. Numerical study of the phase separation in binary lipid membrane containing protein inclusions under stationary shear flow.

    Science.gov (United States)

    Chen, Xiao-Bo; Shi, Hui-Ji; Niu, Li-Sha

    2009-03-26

    The phase separation of lipids is believed to be responsible for the formation of lipid rafts in biological cell membrane. In the present work, a continuum model and a particle model are constructed to study the phase separation in binary lipid membrane containing inclusions under stationary shear flow. In each model, employing the cell dynamical system (CDS) approach, the kinetic equations of the confusion-advection process are numerically solved. Snapshot figures of the phase morphology are performed to intuitively display such phase evolving process. Considering the effects from both the inclusions and the shear flow, the time growth law of the characteristic domain size is discussed.

  19. Bioenhanced dissolution of dense non-aqueous phase of trichloroethylene as affected by iron reducing conditions: model systems and environmental samples.

    Science.gov (United States)

    Paul, Laiby; Smolders, Erik

    2015-01-01

    The anaerobic biotransformation of trichloroethylene (TCE) can be affected by competing electron acceptors such as Fe (III). This study assessed the role of Fe (III) reduction on the bioenhanced dissolution of TCE dense non-aqueous phase liquid (DNAPL). Columns were set up as 1-D diffusion cells consisting of a lower DNAPL layer, a layer with an aquifer substratum and an upper water layer that is regularly refreshed. The substrata used were either inert sand or sand coated with 2-line ferrihydrite (HFO) or two environmental Fe (III) containing samples. The columns were inoculated with KB-1 and were repeatedly fed with formate. In none of the diffusion cells, vinyl chloride or ethene was detected while dissolved and extractable Fe (II) increased strongly during 60 d of incubation. The cis-DCE concentration peaked at 4.0 cm from the DNAPL (inert sand) while it was at 3.4 cm (sand+HFO), 1.7 cm and 2.5 cm (environmental samples). The TCE concentration gradients near the DNAPL indicate that the DNAPL dissolution rate was larger than that in an abiotic cell by factors 1.3 (inert sand), 1.0 (sand+HFO) and 2.2 (both environmental samples). This results show that high bioavailable Fe (III) in HFO reduces the TCE degradation by competitive Fe (III) reduction, yielding lower bioenhanced dissolution. However, Fe (III) reduction in environmental samples was not reducing TCE degradation and the dissolution factor was even larger than that of inert sand. It is speculated that physical factors, e.g. micro-niches in the environmental samples protect microorganisms from toxic concentrations of TCE.

  20. Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes

    Directory of Open Access Journals (Sweden)

    Santhosh PB

    2015-09-01

    Full Text Available Poornima Budime Santhosh,1,* Barbara Drašler,2,* Damjana Drobne,2 Mateja Erdani Kreft,3 Slavko Kralj,4 Darko Makovec,4 Nataša Poklar Ulrih1,5 1Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, 2Department of Biology, Biotechnical Faculty, University of Ljubljana, 3Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, 4Department for Materials Synthesis, Jožef Stefan Institute, 5Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Ljubljana, Slovenia *These authors share equal first authorship Abstract: Superparamagnetic iron oxide nanoparticles (SPIONs with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to be ~11 nm, silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm. Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a

  1. Focal junctions retard lateral movement and disrupt fluid phase connectivity in the plasma membrane

    DEFF Research Database (Denmark)

    Vind-Kezunovic, D.; Wojewodzka, U.; Gniadecki, R.

    2008-01-01

    containing liquid-ordered (L-o) lipids. Indeed, values of maximal fluorescence recovery after photobleaching revealed that the long-range mobility of cholera toxin B subunit (CTB, marker of L-o) was similar to 1.5-fold retarded within the focal junctions compared to the surrounding membrane. However, 1......,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI-C-18:0), which specifically partitions to the liquid-disordered (L-d), non-raft phase, was also enriched in focal junctions and its mobility was slightly retarded. Cross-linking of GM(1) by CTB or raft aggregation by methyl...

  2. NON-INVASIVE DETERMINATION OF THE LOCATION AND DISTRBUTION OF FREE-PHASE DENSE NONAQUEOUS PHASE LIQUIDS (DNAPL) BY SEISMIC REFLECTION TECHNIQUES

    Energy Technology Data Exchange (ETDEWEB)

    Michael G. Waddell; William J. Domoracki; Jerome Eyer

    2003-01-01

    The Earth Sciences and Resources Institute, University of South Carolina is conducting a proof of concept study to determine the location and distribution of subsurface DNAPL carbon tetrachloride (CCl{sub 4}) contamination at the 216-Z-9 crib, 200 West area, DOE Hanford Site, Washington by use of two-dimensional high-resolution seismic reflection surveys and borehole geophysical data. The study makes use of recent advances in seismic reflection amplitude versus offset (AVO) technology to directly detect the presence of subsurface DNAPL. The techniques proposed are noninvasive means of site characterization and direct free-phase DNAPL detection. This final report covers the results of Tasks 1, 2, and 3. Task (1) contains site evaluation and seismic modeling studies. The site evaluation consists of identifying and collecting preexisting geological and geophysical information regarding subsurface structure and the presence and quantity of DNAPL. The seismic modeling studies were undertaken to determine the likelihood that an AVO response exists and its probable manifestation. Task (2) is the design and acquisition of 2-D seismic reflection data to image areas of probable high concentration of DNAPL. Task (3) is the processing and interpretation of the 2-D data. During the commission of these tasks four seismic reflection profiles were collected. Subsurface velocity information was obtained by vertical seismic profile surveys in three wells. The interpretation of these data is in two parts. Part one is the construction and interpretation of structural contour maps of the contact between the Hanford Fine unit and the underlying Plio/Pleistocene unit and of the contact between the Plio/Pleistocene unit and the underlying caliche layer. These two contacts were determined to be the most likely surfaces to contain the highest concentration CCl{sub 4}. Part two of the interpretation uses the results of the AVO modeling to locate any seismic amplitude anomalies that might be

  3. Characterisation of dense non-aqueous phase liquids of coal tar using comprehensive two-dimensional gas chromatography coupled with time of flight mass spectrometry.

    Science.gov (United States)

    Gauchotte-Lindsay, Caroline; McGregor, Laura; Richards, Phil; Kerr, Stephanie; Glenn, Aliyssa; Thomas, Russell; Kalin, Robert

    2013-04-01

    Comprehensive two-dimensional gas chromatography (GCxGC) is a recently developed analytical technique in which two capillary columns with different stationary phases are placed in series enabling planar resolution of the analytes. The resolution power of GCxGC is one order of magnitude higher than that of one dimension gas chromatography. Because of its high resolution capacity, the use of GCxGC for complex environmental samples such as crude oils, petroleum derivatives and polychlorinated biphenyls mixtures has rapidly grown in recent years. We developed a one-step method for the forensic analysis of coal tar dense non-aqueous phase liquids (DNAPLs) from former manufactured gas plant (FMGP) sites. Coal tar is the by-product of the gasification of coal for heating and lighting and it is composed of thousands of organic and inorganic compounds. Before the boom of natural gases and oils, most towns and cities had one or several manufactured gas plants that have, in many cases, left a devastating environmental print due to coal tar contamination. The fate of coal tar DNAPLs, which can persist in the environment for more than a hundred years, is therefore of crucial interest. The presented analytical method consists of a unique clean-up/ extraction stage by pressurized liquid extraction and a single analysis of its organic chemical composition using GCxGC coupled with time of flight mass spectrometry (TOFMS). The chemical fingerprinting is further improved by derivatisation by N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) of the tar compounds containing -OH functions such as alcohols and carboxylic acids. We present here how, using the logical order of elution in GCxGC-TOFMS system, 1) the identification of never before observed -OH containing compounds is possible and 2) the isomeric selectivity of an oxidation reaction on a DNAPL sample can be revealed. Using samples collected at various FMGP sites, we demonstrate how this GCxGC method enables the simultaneous

  4. 高密度二氧化碳技术在食品加工中的应用研究%Research of the application of dense phase carbon dioxide in food processing

    Institute of Scientific and Technical Information of China (English)

    刘文营; 黄丽燕; 卢晓明; 张强; 赵维高; 王旭清; 韩兆鹏; 刘旭明

    2011-01-01

    As an important non-thermal processing technique,Dense Phase Carbon Dioxide(DPCD)has become one of the most active technologies for the inactivation of microorganisms,enzymes and ameliorate characters. The research progress of the application of DPCD in food processing was focused on,in the hope of providing serviceable message for intensive study and extensive use.%作为一项重要的非热加工技术,高密度二氧化碳(Dense Phase Carbon Dioxide,DPCD)技术已经成为目前食品杀菌、钝酶和改善食品品质上较为活跃的研究方向之一。对DPCD在食品加工领域的研究进展进行了综述,以期为DPCD技术的深入研究与广泛应用提供参考。

  5. 槽车密相补气式气力输送系统的设计%Design of air conveying system of tank trailer dense phase replenish gas type

    Institute of Scientific and Technical Information of China (English)

    言仿雷; 罗宝东

    2001-01-01

    介绍密相气力输送的基本原理和技术,一种采用密相脉冲补气式气力输送PET切片的槽车贮罐运输、中转、卸料、仓贮的系统的建立,节约投资、降低能耗,提高了经济效益.%Basic principle and technology of dense phase air conve ying were introduced,a system was built which dense phase impluse replenish gas air conveying tank trailer storage was used to transport,transfer,discharge and store PET chip.The investment was saved,the energy consumption was reduced,the ecnomic benefit was improved.

  6. Fabrication of phosphotungstic acid functionalized mesoporous silica composite membrane by alternative tape-casting incorporating phase inversion technique

    Science.gov (United States)

    Bai, Li; Zhang, Lan; He, Hong Quan; Rasheed, Raj Kamal S./O. Abdul; Zhang, Cai Zhi; Ding, Ovi Lian; Chan, Siew Hwa

    2014-01-01

    Meso-porous silica (MCM-41) membranes functionalized by phosphotungstic acid (HPW) for high temperature proton exchange membrane fuel cells (HT-PEMFCs) are successfully developed by a cost-effective tape-casting incorporating phase inversion and vacuum assisted wet impregnation techniques. The microstructure of the membrane is characterized by field emission scanning electron microscopy (FESEM). The effect of MCM-41 content on the tensile strength, ultimate elongation, and weight gain ratio and swelling ratio in water/methanol of the membranes are investigated in detail. The thermal stability of MCM-41 membrane with/without HPW is analyzed by thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) techniques. In particular, the effects of HPW loading and MCM-41 content on the proton conductivity of HPW/MCM-41 membranes are studied comprehensively. The results on the swelling ratio and tensile tension show that the developed membranes can be applied as an electrolyte membrane for HT-PEMFCs. The developed MCM-41 membrane, in which polyethersulfone (PESf) is used as the supporting backbone, is able to operate up to 200 °C. The single cell assembled from HPW/MCM-41 membrane with 70 wt.% HPW loading gives a peak output power of ∼230 mW cm-2 and ∼125 mW cm-2 in H2/air at 90 °C and in methanol/air at 150 °C without any humidification, respectively.

  7. Hydrophobic Mismatch and Phase Transition in a Membrane Composed by a Mixture of Linear and Bola Phospholipids

    Science.gov (United States)

    Longo, Gabriel; Szleifer, Igal

    2006-03-01

    Archeobacteria are microorganisms that can survive and proliferate in extreme habitats, such as high salt concentration environments, anaerobic conditions, and high or low temperatures. A membrane composed of bolaform phospholipids is what gives these unique survival qualities to the bacteria. The nature and composition of this membrane has not yet been elucidated. In this work, a membrane composed by a mixture of linear and bola phospholipids is studied using a molecular theory. The effect of changing the fraction of bolaform phospholipids, as well as the length of the hydrocarbon chain of the linear lipid are studied. A phase separation in the mixture between a thin bola rich membrane and a thick linear rich membrane is found. The thin membrane is mainly composed by ``spanning'' bola molecules whose polar heads are in opposed hydrophilic regions of the membrane. The phase separation is only present when the hydrocarbon chains of both molecular species have comparable sizes. The driving force for the phase separation is the size matching between the hydrophobic chains of the linear phospholipid and the spanning bola lipid.

  8. Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

    KAUST Repository

    Karunakaran, Madhavan

    2016-03-11

    In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

  9. Capacitive Detection of Low-Enthalpy, Higher-Order Phase Transitions in Synthetic and Natural Composition Lipid Membranes.

    Science.gov (United States)

    Taylor, Graham J; Heberle, Frederick A; Seinfeld, Jason S; Katsaras, John; Collier, C Patrick; Sarles, Stephen A

    2017-09-05

    In-plane lipid organization and phase separation in natural membranes play key roles in regulating many cellular processes. Highly cooperative, first-order phase transitions in model membranes consisting of few lipid components are well understood and readily detectable via calorimetry, densitometry, and fluorescence. However, far less is known about natural membranes containing numerous lipid species and high concentrations of cholesterol, for which thermotropic transitions are undetectable by the above-mentioned techniques. We demonstrate that membrane capacitance is highly sensitive to low-enthalpy thermotropic transitions taking place in complex lipid membranes. Specifically, we measured the electrical capacitance as a function of temperature for droplet interface bilayer model membranes of increasing compositional complexity, namely, (a) a single lipid species, (b) domain-forming ternary mixtures, and (c) natural brain total lipid extract (bTLE). We observed that, for single-species lipid bilayers and some ternary compositions, capacitance exhibited an abrupt, temperature-dependent change that coincided with the transition detected by other techniques. In addition, capacitance measurements revealed transitions in mixed-lipid membranes that were not detected by the other techniques. Most notably, capacitance measurements of bTLE bilayers indicated a transition at ∼38 °C not seen with any other method. Likewise, capacitance measurements detected transitions in some well-studied ternary mixtures that, while known to yield coexisting lipid phases, are not detected with calorimetry or densitometry. These results indicate that capacitance is exquisitely sensitive to low-enthalpy membrane transitions because of its sensitivity to changes in bilayer thickness that occur when lipids and excess solvent undergo subtle rearrangements near a phase transition. Our findings also suggest that heterogeneity confers stability to natural membranes that function near

  10. Membrane System for Recovery of Volatile Organic Compounds from Remediation Off-Gases.: Phase 1.

    Energy Technology Data Exchange (ETDEWEB)

    Wijmans, J.G.; Goakey, S.; Wang, X.; Baker, R.W.; Kaschemekat, J.H.

    1997-04-01

    In situ vacuum extraction, air or steam sparging, and vitrification are widely used methods of remediating soil contaminated with volatile organic compounds (VOCs). All of these processes produce a VOC-laden air stream from which the VOC must be removed before the air can be discharged or recycled to the generating process. Treatment of these off-gases is often a major portion of the cost of the remediation project. Carbon adsorption and catalytic incineration, the most common methods of treating these gas streams, suffer from significant drawbacks. This report covers the first phase of a two-phase project. The first phase involved the laboratory demonstration of the water separation section of the unit, the production and demonstration of new membrane modules to improve the separation, the design studies required for the demonstration system, and initial contacts with potential field sites. In the second phase, the demonstration system will be built and, after a short laboratory evaluation, will be tested at two field sites.

  11. INFLUENCE OF ALCOHOL-BASED NONSOLVENTS ON THE FORMATION AND MORPHOLOGY OF PVDF MEMBRANES IN PHASE INVERSION PROCESS

    Institute of Scientific and Technical Information of China (English)

    Dan-ying Zuo; Bao-ku Zhu; Jian-hua Cao; You-yi Xu

    2006-01-01

    Through the preparation of PVDF membranes using various nonsolvent coagulation baths following the phase inversion process, the influence of alcohol-based nonsolvents on the formation and structure of PVDF membranes were investigated. The light scattering and light transmission measurements were used to characterize the equilibrium phase diagram and the gelation speed, respectively. The locations of the crystallization-induced gelation boundaries for various systems and precipitation processes were explained from the corresponding thermodynamic and kinetic parameters. It was found that the better affinity between alcohol-based nonsolvents and DMAc solvent caused the gelation boundaries further away from the PVDF-DMAc axis with the coagulation bath varying from water, methanol, ethanol to iso-propanol. Due to the lower exchange rate of DMAc and alcohols, the delayed demixing took place for the membrane-forming using alcohols as baths, and the delayed time became longer when the coagulation bath was changed from methanol, ethanol to iso-propanol.The characterization results of membranes indicate that the influence of nonsolvents on the phase diagram and the precipitation process are in agreement with those on the membrane morphology. The better thermodynamic stability and a low exchange diffusion rate of PVDF/DMAc/alcohols favor the liquid-solid phase separation in gelation process, and therefore yield the membranes with a porous upper surface, a particular bottom surface and symmetrical structure.

  12. Electromagnetic induction of nanoscale zerovalent iron particles accelerates the degradation of chlorinated dense non-aqueous phase liquid: Proof of concept.

    Science.gov (United States)

    Phenrat, Tanapon; Kumloet, Itsaraphong

    2016-12-15

    In this study, a novel electromagnetically enhanced treatment concept is proposed for in situ remediation of a source zone of chlorinated dense non-aqueous phase liquid (DNAPL) that is slowly dissolved, causing contaminated groundwater for centuries. Here, we used polystyrene sulfonate (PSS)-modified nanoscale zerovalent iron (NZVI) particles (ferromagnetic) in combination with a low frequency (LF) (150 kHz) AC electromagnetic field (EMF) to accelerate the degradation of the DNAPLs via enhanced dissolution and reductive dechlorination. Trichloroethylene (TCE) and tetrachloroethylene (PCE) were used in a bench-scaled evaluation. The PSS-modified NZVI successfully targeted the DNAPL/water interface, as evidenced by the Pickering emulsion formation. Dechlorination of TCE- and PCE-DNAPL was measured by quantifying the by-product formation (acetylene, ethene, and ethane). Without magnetic induction heating (MIH) by LF EMF, PSS-modified NZVI transformed TCE- and PCE-DNAPL to ethene and ethane at the rate constants of 12.19 × 10(-3) and 1.00 × 10(-3) μmol/h/m(2), respectively, following pseudo zero-order reactions. However, four MIH cycles of PSS-NZVI increased the temperature up to 87 °C and increased the rate constants of TCE-DNAPL and PCE-DNAPL up to 14.58 and 58.01 times, respectively, in comparison to the dechlorination rate without MIH. Theoretical analysis suggested that the MIH of the PSS-modified NZVI enhanced the dechlorination of TCE- and PCE-DNAPL via the combination of the enhanced thermal dissolution of DNAPL, the effect of increasing the temperature on the rate constant (the Arrhenius equation), and the accelerated NZVI corrosion. Nevertheless, the effect of the Arrhenius equation was dominant. For the first time, this proof-of-concept study reveals the potential for using polyelectrolyte-modified NZVI coupled with LF EMF as a combined remediation technique for increasing the rate and completeness of in situ chlorinated DNAPL source remediation

  13. Dense topological spaces and dense continuity

    Science.gov (United States)

    Aldwoah, Khaled A.

    2013-09-01

    There are several attempts to generalize (or "widen") the concept of topological space. This paper uses equivalence relations to generalize the concept of topological space via the concept of equivalence relations. By the generalization, we can introduce from particular topology on a nonempty set X many new topologies, we call anyone of these new topologies a dense topology. In addition, we formulate some simple properties of dense topologies and study suitable generalizations of the concepts of limit points, closeness and continuity, as well as Jackson, Nörlund and Hahn dense topologies.

  14. Sugar-induced blue membrane: release of divalent cations during phase transition of purple membranes observed in sugar-derived glasses.

    Science.gov (United States)

    Rhinow, Daniel; Hampp, Norbert A

    2008-04-17

    The formation of blue membrane from purple membranes (PM) has been observed in glassy films made from PM and various sugars. The phase transition of PM at about 70 degrees C causes the complexation of divalent cations to be weakened. The vicinal diol structures in sugars are capable to complex divalent cations and delocalize them throughout the matrix as long as its glass transition temperature is lower than the phase transition temperature of PM. The loss of divalent cations from bacteriorhodopsin (BR), the only protein in PM, causes the formation of blue membrane (BM), which is accompanied by a loss of beta-sheet structure observable in the infrared spectrum. Glassy sugars are particular useful to observe this transition, as sugar entrapment does not restrict conformational changes of BR but rather retards them. The material obtained was named sugar-induced blue membrane (SIBM). The formation of SIBM is inhibited by the addition of divalent cations. Furthermore, SIBM is reverted immediately to PM by addition of water. A characteristic time dependence of the thermal reversion of SIBM to PM proves that the phase transition of PM triggers the release and uptake of divalent cations and the corresponding color change.

  15. Hyperons in dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Dapo, Haris

    2009-01-28

    -body force with a density-dependent interaction. This density-dependent interaction is fitted to the saturation properties of nuclear matter and used together with the V{sub low} {sub k} potential. The study of in-medium properties with these interactions is accomplished with a combination of Fermi liquid theory and random phase approximation(RPA). The Fermi liquid theory is then used to obtain the strength of the particle-hole interactions. The medium's response to neutrinos is represented via changes of the polarization function in the random phase approximation. The properties of neutrinos in dense matter are studied in both, Hartree-Fock and random phase, approximation. To understand how the changes in the mediums response alter the behavior of neutrinos in dense matter, we calculate the neutrino cross section and the neutrino mean free path. The neutrinos interact with baryons and leptons through the weak interaction, hence we calculate these for both neutral and charged currents. (orig.)

  16. Protein sorting by lipid phase-like domains supports emergent signaling function in B lymphocyte plasma membranes.

    Science.gov (United States)

    Stone, Matthew B; Shelby, Sarah A; Núñez, Marcos F; Wisser, Kathleen; Veatch, Sarah L

    2017-02-01

    Diverse cellular signaling events, including B cell receptor (BCR) activation, are hypothesized to be facilitated by domains enriched in specific plasma membrane lipids and proteins that resemble liquid-ordered phase-separated domains in model membranes. This concept remains controversial and lacks direct experimental support in intact cells. Here, we visualize ordered and disordered domains in mouse B lymphoma cell membranes using super-resolution fluorescence localization microscopy, demonstrate that clustered BCR resides within ordered phase-like domains capable of sorting key regulators of BCR activation, and present a minimal, predictive model where clustering receptors leads to their collective activation by stabilizing an extended ordered domain. These results provide evidence for the role of membrane domains in BCR signaling and a plausible mechanism of BCR activation via receptor clustering that could be generalized to other signaling pathways. Overall, these studies demonstrate that lipid mediated forces can bias biochemical networks in ways that broadly impact signal transduction.

  17. Dose-dense adjuvant chemotherapy in premenopausal breast cancer patients: A pooled analysis of the MIG1 and GIM2 phase III studies.

    Science.gov (United States)

    Lambertini, Matteo; Ceppi, Marcello; Cognetti, Francesco; Cavazzini, Giovanna; De Laurentiis, Michele; De Placido, Sabino; Michelotti, Andrea; Bisagni, Giancarlo; Durando, Antonio; Valle, Enrichetta; Scotto, Tiziana; De Censi, Andrea; Turletti, Anna; Benasso, Marco; Barni, Sandro; Montemurro, Filippo; Puglisi, Fabio; Levaggi, Alessia; Giraudi, Sara; Bighin, Claudia; Bruzzi, Paolo; Del Mastro, Lucia

    2017-01-01

    No evidence exists to recommend a specific chemotherapy regimen in young breast cancer patients. We performed a pooled analysis of two randomised clinical trials to evaluate the efficacy of adjuvant dose-dense chemotherapy in premenopausal breast cancer patients and its impact on the risk of treatment-induced amenorrhoea. In the MIG1 study, node-positive or high-risk node-negative patients were randomised to 6 cycles of fluorouracil/epirubicin/cyclophosphamide every 2 (dose-dense) or 3 (standard-interval) weeks. In the GIM2 study, node-positive patients were randomised to 4 cycles of dose-dense or standard-interval EC or FEC followed by 4 cycles of dose-dense or standard-interval paclitaxel. Using individual patient data, the hazard ratio (HR) for overall survival by means of a Cox proportional hazards model and the odds ratio for treatment-induced amenorrhoea through a logistic regression model were calculated for each study. A meta-analysis of the two studies was performed using the random effect model to compute the parameter estimates. A total of 1,549 patients were included. Dose-dense chemotherapy was associated with a significant improved overall survival as compared to standard-interval chemotherapy (HR, 0.71; 95% confidence intervals [CI], 0.54-0.95; p = 0.021). The pooled HRs were 0.78 (95% CI, 0.54-1.12) and 0.65 (95% CI, 0.40-1.06) for patients with hormone receptor-positive and -negative tumours, respectively (interaction p = 0.330). No increased risk of treatment-induced amenorrhoea was observed with dose-dense chemotherapy (odds ratio, 1.00; 95% CI, 0.80-1.25; p = 0.989). Dose-dense adjuvant chemotherapy may be considered the preferred treatment option in high-risk premenopausal breast cancer patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Triton X-114 phase separation in the isolation and purification of mouse liver microsomal membrane proteins.

    Science.gov (United States)

    Mathias, Rommel A; Chen, Yuan-Shou; Kapp, Eugene A; Greening, David W; Mathivanan, Suresh; Simpson, Richard J

    2011-08-01

    Integral membrane proteins (IMPs) mediate several cellular functions including cell adhesion, ion and nutrient transport, and cell signalling. IMPs are typically hard to isolate and purify due to their hydrophobic nature and low cellular abundance, however, microsomes are small lipid vesicles rich in IMPs, which form spontaneously when cells are mechanically disrupted. In this study, we have employed mouse liver microsomes as a model for optimising a method for IMP isolation and characterisation. Microsomes were collected by differential centrifugation, purified with sodium carbonate, and subjected to GeLC-MS/MS analysis. A total of 1124 proteins were identified in the microsome fraction, with 47% (524/1124) predicted by TMHMM to contain at least one transmembrane domain (TMD). The ability of phase partitioning using the detergent Triton X-114 (TX-114) to further enrich for membrane proteins was evaluated. Microsomes were subjected to successive rounds of solubility-based phase separation, with proteins partitioning into the aqueous phase, detergent phase, or TX-114-insoluble pellet fraction. GeLC-MS/MS analysis of the three TX-114 fractions identified 1212 proteins, of which 146 were not detected in the un-fractionated microsome sample. Conspicuously, IMPs partitioned to the detergent phase, with 56% (435/770) of proteins identified in that fraction containing at least one TMD. GO Slim characterisation of the microsome proteome revealed enrichment of proteins from the endoplasmic reticulum, mitochondria, Golgi apparatus, endosome, and cytoplasm. Further, enzymes including monooxygenases were well represented with 35 cytochrome P450 identifications (CYPs 1A2, 2A5, 2A12, 2B10, 2C29, 2C37, 2C39, 2C44, 2C50, 2C54. 2C67, 2C68, 2C70, 2D10, 2D11, 2D22, 2D26, 2D9, 2E1, 2F2, 2J5, 2U1, 3A11, 3A13, 3A25, 4A10, 4A12A, 4A12B, 4F13, 4F14, 4F15, 4V3, 51,7B1, and 8B1). Evaluation of biological processes showed enrichment of proteins involved in fatty acid biosynthesis and

  19. Modeling Discontinuous Phase Transitions in Gel Membranes: Focus on Hysteresis and Feedback Mechanisms

    Science.gov (United States)

    Kuksenok, Olga

    Feedback mechanisms are vital in a number of processes in biological systems. For example, feedback loops play an essential role during a limb development in mammals and are responsible for the asymmetric cell division to constrain the growth in plants to the specific regions. An integration of well-controlled feedback loops into the fully synthetic materials is an important step in designing a range of biomimetic functionalities. Herein, we focus on hydrogels functionalized with light-sensitive trisodium salt of copper chlorophyllin and study discontinuous phase transitions in these systems. Prior experimental studies had shown that illumination of these functionalized gels results in their heating and in discontinuous, first order phase transition upon the variation in temperature. Herein, we develop the first computational model for these gels; the framework of the model is based on the gel Lattice Spring Model, in this work we account for the gel heating under the illumination. The results of our simulations are in a good agreement with prior experimental studies. We focus on pattern development during the volume phase transitions in membranes of various thicknesses and show that one can effectively utilize light intensity to remotely control feedback loops in these systems.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mazanec, T.J.

    1997-07-01

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

  1. 高密度CO2对虾优势腐败菌的杀菌效果及机理%Sterilizing effect of dense phase carbon dioxide on dominant spoilage bacteria from shrimp and its mechanism

    Institute of Scientific and Technical Information of China (English)

    刘书成; 张良; 吉宏武※; 屈小娟; 章超桦; 郝记明

    2013-01-01

      为了探讨高密度CO2(dense phase carbon dioxide,DPCD)对水产品腐败菌的杀菌效果和机制,以一株凡纳滨对虾优势腐败菌(Chryseobacterium sp. LV1)为研究对象,研究了DPCD处理温度(30~55℃)、压力(5~25 MPa)、时间(5~60 min)对杀菌效果的影响,分析了DPCD处理前后该菌理化性质的变化。结果表明:DPCD对其具有较好的杀菌效果,温度升高、压力增大、延长时间都会增强杀菌效果,而且超临界CO2比亚临界CO2的杀菌效果好。当在45℃、15 MPa和55℃、15 MPa下处理菌悬液30 min时,菌落总数均能下降5个对数;菌悬液的pH值从6.97分别下降至5.58和5.56;细胞外蛋白由最初的78.69μg/mL分别增至151.91和157.40μg/mL,200~800 nm范围内的吸光度值增大,这说明DPCD处理改变了其细胞膜的通透性,造成胞内蛋白质和核酸泄漏;可溶性和不溶性蛋白的电泳图谱发生变化,说明DPCD处理能够诱导Chryseobacterium sp. LV1可溶性蛋白质变性,降低其溶解度;能够钝化与其新陈代谢相关的14种酶类;但不会造成其DNA的降解。因此,DPCD处理致使其理化性质的改变可能是杀菌的主要原因之一。研究结果将为DPCD技术在对虾加工中的应用提供参考。%  Dense phase carbon dioxide (DPCD) is a non-thermal pasteurization method that affects microorganisms and enzymes through molecular effects of CO2 under pressures below 50MPa and temperature below 60℃. The DPCD sterilization technique could be one of the most promising techniques for sterilizing foods without exposing them to adverse effects of heat, thereby retaining their fresh physical, nutritional, and sensory qualities. In order to investigate the sterilization effect and mechanism of aquatic product spoilage bacteria induced by dense phase carbon dioxide (DPCD), using a strain of Litopenaeus vannamei dominant spoilage bacteria (Chryseobacterium sp. LV

  2. Continuous Hydrolysis and Liquid–Liquid Phase Separation of an Active Pharmaceutical Ingredient Intermediate Using a Miniscale Hydrophobic Membrane Separator

    DEFF Research Database (Denmark)

    Cervera Padrell, Albert Emili; Morthensen, Sofie Thage; Lewandowski, Daniel Jacob

    2012-01-01

    Continuous hydrolysis of an active pharmaceutical ingredient intermediate, and subsequent liquid–liquid (L-L) separation of the resulting organic and aqueous phases, have been achieved using a simple PTFE tube reactor connected to a miniscale hydrophobic membrane separator. An alkoxide product...... a PTFE membrane with 28 cm2 of active area. A less challenging separation of water and toluene was achieved at total flow rates as high as 80 mL/min, with potential to achieve even higher flow rates. The operability and flexibility of the membrane separator and a plate coalescer were compared...

  3. Effect of membrane structure on the action of polyenes II: nystatin activity along the phase diagram of ergosterol- and cholesterol-containing POPC membranes.

    Science.gov (United States)

    González-Damián, J; Ortega-Blake, I

    2010-09-01

    Pores formed by the polyene antibiotic nystatin were studied in solvent-free lipid membranes. The membranes were formed by the tip-dip technique using 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) with different mol fractions (0-50%) of cholesterol or ergosterol. The effects of the mol fraction of sterol and of temperature variation (15-35°C) on the activity of the pores, their unitary conductances, lifetimes and time average conductances were studied. The results were used to analyze the behavior of nystatin channels along the phase diagrams previously reported for these lipid mixtures and to propose that membrane structure is the determinant factor for the known ergosterol/cholesterol selectivity.

  4. Segregated phases in pulmonary surfactant membranes do not show coexistence of lipid populations with differentiated dynamic properties

    DEFF Research Database (Denmark)

    Bernardino de la Serna, Jorge; Orädd, Greger; Bagatolli, Luis

    2009-01-01

    The composition of pulmonary surfactant membranes and films has evolved to support a complex lateral structure, including segregation of ordered/disordered phases maintained up to physiological temperatures. In this study, we have analyzed the temperature-dependent dynamic properties of native...... surfactant membranes and membranes reconstituted from two surfactant hydrophobic fractions (i.e., all the lipids plus the hydrophobic proteins SP-B and SP-C, or only the total lipid fraction). These preparations show micrometer-sized fluid ordered/disordered phase coexistence, associated with a broad...... from the two types of surfactant hydrophobic extract. These latter results suggest that lipid dynamics are similar in the coexisting fluid phases observed by fluorescence microscopy. Additionally, it is found that surfactant proteins significantly reduce the average intramolecular lipid mobility...

  5. Interaction between Antibacterial Peptide Apep10 and Escherichia coli Membrane Lipids Evaluated Using Liposome as Pseudo-Stationary Phase

    Science.gov (United States)

    Li, Man

    2017-01-01

    Liposomes constructed from Escherichia coli membrane lipids were used as a pseudo-stationary phase in capillary electrophoresis and immobilised liposome chromatography to evaluate the interaction between antibacterial peptide (ABP) Apep10 and bacterial membrane lipids. The peptide mobility decreased as the concentration of liposomes increased, providing evidence for the existence of this interaction. The binding constant between Apep10 and the Escherichia coli membranes lipid liposome was higher than that of Apep10 with a mixed phospholipids liposome at the same temperature. The capillary electrophoresis results indicate that the binding ability of Apep10 with a liposome was dependent on the liposome’s lipid compositions. Thermodynamic analysis by immobilised liposome chromatography indicated that hydrophobic and electrostatic effects contributed to the partitioning of Apep10 in the membrane lipids. The liposomes constructed from bacterial membrane lipid were more suitable as the model membranes used to study dynamic ABP/membrane interactions than those constructed from specific ratios of particular phospholipids, with its more biomimetic phospholipid composition and contents. This study provides an appropriate model for the evaluation of ABP-membrane interactions. PMID:28052090

  6. Phase-Sensitive Noise Suppression in a Photoacoustic Sensor based on Acoustic Circular Membrane Modes

    CERN Document Server

    Lassen, Mikael; Balslev-Harder, David; Petersen, Jan C

    2014-01-01

    A photoacoustic (PA) sensor based on higher order acoustic modes is demonstrated. The PA sensor is designed to enhance the gas-detection performance and simultaneously suppress ambient noise sources (e.g. flow noise, electrical noise and external acoustic noise). Two microphones are used and positioned such that the PA signals are ($\\pi$) out of phase. Ambient acoustic noise are approximately in the same phase and will be subtracted and thus improve the SNR. In addition, by placing the gas in- and outlets so that the gas flows through the node of the first higher order membrane mode the coupling of flow noise is approximately 20 dB lower compared with flow through the fundamental mode at 5 L/min. The noise reduction and thus the increase in sensitivity is demonstrated by measuring vibrational lines of methanol and methane using a broadband interband cascade laser emitting radiation at 3.38 $\\mu$m. A signal-to-noise improvement of 20 (26 dB) using higher order modes are demonstrated compared with the fundament...

  7. Uptake rate constants and partition coefficients for vapor phase organic chemicals using semipermeable membrane devices (SPMDs)

    Science.gov (United States)

    Cranor, W.L.; Alvarez, D.A.; Huckins, J.N.; Petty, J.D.

    2009-01-01

    To fully utilize semipermeable membrane devices (SPMDs) as passive samplers in air monitoring, data are required to accurately estimate airborne concentrations of environmental contaminants. Limited uptake rate constants (kua) and no SPMD air partitioning coefficient (Ksa) existed for vapor-phase contaminants. This research was conducted to expand the existing body of kinetic data for SPMD air sampling by determining kua and Ksa for a number of airborne contaminants including the chemical classes: polycyclic aromatic hydrocarbons, organochlorine pesticides, brominated diphenyl ethers, phthalate esters, synthetic pyrethroids, and organophosphate/organosulfur pesticides. The kuas were obtained for 48 of 50 chemicals investigated and ranged from 0.03 to 3.07??m3??g-1??d-1. In cases where uptake was approaching equilibrium, Ksas were approximated. Ksa values (no units) were determined or estimated for 48 of the chemicals investigated and ranging from 3.84E+5 to 7.34E+7. This research utilized a test system (United States Patent 6,877,724 B1) which afforded the capability to generate and maintain constant concentrations of vapor-phase chemical mixtures. The test system and experimental design employed gave reproducible results during experimental runs spanning more than two years. This reproducibility was shown by obtaining mean kua values (n??=??3) of anthracene and p,p???-DDE at 0.96 and 1.57??m3??g-1??d-1 with relative standard deviations of 8.4% and 8.6% respectively.

  8. Visualization of membrane protein crystals in lipid cubic phase using X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Anna J. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Armour, Wes [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Oxford e-Research Centre, 7 Keble Road, Oxford OX1 3QG (United Kingdom); Axford, Danny; Basham, Mark; Connolley, Thomas; Hall, David R. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Horrell, Sam [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); University of Liverpool, Liverpool L69 3BX (United Kingdom); McAuley, Katherine E.; Mykhaylyk, Vitaliy; Wagner, Armin; Evans, Gwyndaf, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom)

    2013-07-01

    A comparison of X-ray diffraction and radiographic techniques for the location and characterization of protein crystals is demonstrated on membrane protein crystals mounted within lipid cubic phase material. The focus in macromolecular crystallography is moving towards even more challenging target proteins that often crystallize on much smaller scales and are frequently mounted in opaque or highly refractive materials. It is therefore essential that X-ray beamline technology develops in parallel to accommodate such difficult samples. In this paper, the use of X-ray microradiography and microtomography is reported as a tool for crystal visualization, location and characterization on the macromolecular crystallography beamlines at the Diamond Light Source. The technique is particularly useful for microcrystals and for crystals mounted in opaque materials such as lipid cubic phase. X-ray diffraction raster scanning can be used in combination with radiography to allow informed decision-making at the beamline prior to diffraction data collection. It is demonstrated that the X-ray dose required for a full tomography measurement is similar to that for a diffraction grid-scan, but for sample location and shape estimation alone just a few radiographic projections may be required.

  9. Myelin membrane assembly is driven by a phase transition of myelin basic proteins into a cohesive protein meshwork.

    Directory of Open Access Journals (Sweden)

    Shweta Aggarwal

    Full Text Available Rapid conduction of nerve impulses requires coating of axons by myelin. To function as an electrical insulator, myelin is generated as a tightly packed, lipid-rich multilayered membrane sheath. Knowledge about the mechanisms that govern myelin membrane biogenesis is required to understand myelin disassembly as it occurs in diseases such as multiple sclerosis. Here, we show that myelin basic protein drives myelin biogenesis using weak forces arising from its inherent capacity to phase separate. The association of myelin basic protein molecules to the inner leaflet of the membrane bilayer induces a phase transition into a cohesive mesh-like protein network. The formation of this protein network shares features with amyloid fibril formation. The process is driven by phenylalanine-mediated hydrophobic and amyloid-like interactions that provide the molecular basis for protein extrusion and myelin membrane zippering. These findings uncover a physicochemical mechanism of how a cytosolic protein regulates the morphology of a complex membrane architecture. These results provide a key mechanism in myelin membrane biogenesis with implications for disabling demyelinating diseases of the central nervous system.

  10. Myelin membrane assembly is driven by a phase transition of myelin basic proteins into a cohesive protein meshwork.

    Science.gov (United States)

    Aggarwal, Shweta; Snaidero, Nicolas; Pähler, Gesa; Frey, Steffen; Sánchez, Paula; Zweckstetter, Markus; Janshoff, Andreas; Schneider, Anja; Weil, Marie-Theres; Schaap, Iwan A T; Görlich, Dirk; Simons, Mikael

    2013-01-01

    Rapid conduction of nerve impulses requires coating of axons by myelin. To function as an electrical insulator, myelin is generated as a tightly packed, lipid-rich multilayered membrane sheath. Knowledge about the mechanisms that govern myelin membrane biogenesis is required to understand myelin disassembly as it occurs in diseases such as multiple sclerosis. Here, we show that myelin basic protein drives myelin biogenesis using weak forces arising from its inherent capacity to phase separate. The association of myelin basic protein molecules to the inner leaflet of the membrane bilayer induces a phase transition into a cohesive mesh-like protein network. The formation of this protein network shares features with amyloid fibril formation. The process is driven by phenylalanine-mediated hydrophobic and amyloid-like interactions that provide the molecular basis for protein extrusion and myelin membrane zippering. These findings uncover a physicochemical mechanism of how a cytosolic protein regulates the morphology of a complex membrane architecture. These results provide a key mechanism in myelin membrane biogenesis with implications for disabling demyelinating diseases of the central nervous system.

  11. Metabolic remodeling of the human red blood cell membrane measured by quantitative phase microscopy

    Science.gov (United States)

    Park, YongKeun; Best, Catherine; Auth, Thorsten; Gov, Nir S.; Safran, Samuel; Popescu, Gabriel

    2011-02-01

    We have quantitatively and systemically measured the morphologies and dynamics of fluctuations in human RBC membranes using a full-field laser interferometry technique that accurately measures dynamic membrane fluctuations. We present conclusive evidence that the presence of adenosine 5'-triphosphate (ATP) facilitates nonequilibrium dynamic fluctuations in the RBC membrane and that these fluctuations are highly correlated with specific regions in the biconcave shape of RBCs. Spatial analysis reveals that these nonequilibrium membrane fluctuations are enhanced at the scale of the spectrin mesh size. Our results indicate the presence of dynamic remodeling in the RBC membrane cortex powered by ATP, which results in nonequilibrium membrane fluctuations.

  12. Streamlined Membrane Proteome Preparation for Shotgun Proteomics Analysis with Triton X-100 Cloud Point Extraction and Nanodiamond Solid Phase Extraction

    OpenAIRE

    Pham, Minh D.; Ting-Chun Wen; Hung-Cheng Li; Pei-Hsuan Hsieh; Yet-Ran Chen; Huan-Cheng Chang; Chau-Chung Han

    2016-01-01

    While mass spectrometry (MS) plays a key role in proteomics research, characterization of membrane proteins (MP) by MS has been a challenging task because of the presence of a host of interfering chemicals in the hydrophobic protein extraction process, and the low protease digestion efficiency. We report a sample preparation protocol, two-phase separation with Triton X-100, induced by NaCl, with coomassie blue added for visualizing the detergent-rich phase, which streamlines MP preparation fo...

  13. Numerical Simulation of Flow Regime in Dense-Phase Pneumatic Conveying with Different Pulverized Coal Particle Sizes%煤粉粒径对密相气力输送流型影响的数值模拟

    Institute of Scientific and Technical Information of China (English)

    彭小敏; 朱立平; 袁竹林

    2012-01-01

    The key problems of current numerical simulation of dense-phase pneumatic conveying were analyzed in this paper. To solve these problems, a new mathematical model for describing the contact force between particles was proposed, and the dense-phase gas-solid two-phase flow (even when the particles packed) could be simulated by the new model. Based on discrete particle modle (DEM), the new model used the solid phase volume concentration and the characteristics of particle motion to describe the contact force between particles to make sure that the new model can not only simulate dilute phase flow like dispersed flow regime but also dense gas-solid two-phase flow (even when the particles packed). The new model was used to numerically study the flow behaviors of dense phase pneumatic conveying at high pressure. The typical flow regimes, such as slug flow and dune flow which agreed well with experimental results, were obtained, and with the increase of particle size, the flow regime of pulverized coal in dense-phase pneumatic conveying changed into dune flow from sedimentation flow and then changed into slug flow from dune flow. The mean slug length decreased while the average solid concentration in horizontal pipe increased with the increase of particle size.%针对目前密相气力输送数值模拟过程中所存在的关键问题,提出了一种描述固相内部相互作用对颗粒运动影响的数学模型,采用该模型能够对稠密气固两相流动(乃至颗粒发生大量沉积的情况)进行数值模拟.新模型在离散颗粒模型的基础上,通过描述颗粒所在局部空间的固相浓度及颗粒群运动特征所建立,使其既能够模拟悬浮流动的稀相颗粒运动,又能模拟管内出现堆积情况的密相气固两相流.利用所建立的数学模型对高压密相煤粉气力输送的颗粒流动过程进行了数值模拟.模拟结果显示,随着颗粒粒径增大,粉体密相气力输送流型从沉积层流变化为沙丘

  14. Atoms in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs.

  15. Quantum dense key distribution

    CERN Document Server

    Degiovanni, I P; Castelletto, S; Rastello, M L; Bovino, F A; Colla, A M; Castagnoli, G C

    2004-01-01

    This paper proposes a new protocol for quantum dense key distribution. This protocol embeds the benefits of a quantum dense coding and a quantum key distribution and is able to generate shared secret keys four times more efficiently than BB84 one. We hereinafter prove the security of this scheme against individual eavesdropping attacks, and we present preliminary experimental results, showing its feasibility.

  16. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-11-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the current research, the electrical conductivity and Seebeck coefficient were measured as a function of temperature in air. Based on these measurements, the charge carrier concentration, net acceptor dopant concentration, activation energy of conduction and mobility were estimated. The studies on the fracture toughness of the LSFT and dual phase membranes at room temperature have been completed and reported previously. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affects the mechanical properties. To study the effect of temperature on the membranes when exposed to an inert environment, the membranes (LAFT and Dual phase) were heat treated at 1000 C in air and N{sub 2} atmosphere and hardness and fracture toughness of the membranes were studied after the treatment. The indentation method was used to find the fracture toughness and the effect of the heat treatment on the mechanical properties of the membranes. Further results on the investigation of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appears to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model will serve to study ''frozen'' profiles in patterned or composite membranes.

  17. Drying increases intracellular partitioning of amphiphilic substances into the lipid phase. Impact On membrane permeability and significance for desiccation tolerance

    Science.gov (United States)

    Golovina; Hoekstra; Hemminga

    1998-11-01

    Previously we proposed that endogenous amphiphilic substances may partition from the aqueous cytoplasm into the lipid phase during dehydration of desiccation-tolerant organ(ism)s and vice versa during rehydration. Their perturbing presence in membranes could thus explain the transient leakage from imbibing organisms. To study the mechanism of this phenomenon, amphiphilic nitroxide spin probes were introduced into the pollen of a model organism, Typha latifolia, and their partitioning behavior during dehydration and rehydration was analyzed by electron paramagnetic resonance spectroscopy. In hydrated pollen the spin probes mainly occurred in the aqueous phase; during dehydration, however, the amphiphilic spin probes partitioned into the lipid phase and had disappeared from the aqueous phase below 0.4 g water g-1 dry weight. During rehydration the probes reappeared in the aqueous phase above 0.4 g water g-1 dry weight. The partitioning back into the cytoplasm coincided with the decrease of the initially high plasma membrane permeability. A charged polar spin probe was trapped in the cytoplasm during drying. Liposome experiments showed that partitioning of an amphiphilic spin probe into the bilayer during dehydration caused transient leakage during rehydration. This was also observed with endogenous amphipaths that were extracted from pollen, implying similar partitioning behavior. In view of the fluidizing effect on membranes and the antioxidant properties of many endogenous amphipaths, we suggest that partitioning with drying may be pivotal to desiccation tolerance, despite the risk of imbibitional leakage.

  18. ANALYSIS OF A MIXED FINITE ELEMENT METHOD FOR A PHASE FIELD BENDING ELASTICITY MODEL OF VESICLE MEMBRANE DEFORMATION

    Institute of Scientific and Technical Information of China (English)

    Qiang Du; Liyong Zhu

    2006-01-01

    In this paper, we study numerical approximations of a recently proposed phase field model for the vesicle membrane deformation governed by the variation of the elastic bending energy. To overcome the challenges of high order nonlinear differential systems and the nonlinear constraints associated with the problem, we present the phase field bending elasticity model in a nested saddle point formulation. A mixed finite element method is then employed to compute the equilibrium configuration of a vesicle membrane with prescribed volume and surface area. Coupling the approximation results for a related linearized problem and the general theory of Brezzi-Rappaz-Raviart, optimal order error estimates for the finite element approximations of the phase field model are obtained. Numerical results areprovided to substantiate the derived estimates.

  19. Preparation of Gas Separation Membranes and their Evaluation

    Directory of Open Access Journals (Sweden)

    R. S. Chauhan

    2004-07-01

    Full Text Available Asymmetric membranes have been prepared form the polysulfone using dry-wet phase-inversion technique. These membranes show a thin dense skin at one surface and porous as well as the selectivity of membranes. In addition an online permeate composition analysis system has also been setup to quantify the concentration fo the two major components of atmospheric ari, namely oxygen and nitrogen using a gas chromatograph. Memvranes have been tested at various feed pressures. Teh developed membranes are capable of enriching atmospheric air to a level of 30 per cent and more.

  20. Gas phase recovery of hydrogen sulfide contaminated polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Kakati, Biraj Kumar; Kucernak, Anthony R. J.

    2014-04-01

    The effect of hydrogen sulfide (H2S) on the anode of a polymer electrolyte membrane fuel cell (PEMFC) and the gas phase recovery of the contaminated PEMFC using ozone (O3) were studied. Experiments were performed on fuel cell electrodes both in an aqueous electrolyte and within an operating fuel cell. The ex-situ analyses of a fresh electrode; a H2S contaminated electrode (23 μmolH2S cm-2); and the contaminated electrode cleaned with O3 shows that all sulfide can be removed within 900 s at room temperature. Online gas analysis of the recovery process confirms the recovery time required as around 720 s. Similarly, performance studies of an H2S contaminated PEMFC shows that complete rejuvenation occurs following 600-900 s O3 treatment at room temperature. The cleaning process involves both electrochemical oxidation (facilitated by the high equilibrium potential of the O3 reduction process) and direct chemical oxidation of the contaminant. The O3 cleaning process is more efficient than the external polarization of the single cell at 1.6 V. Application of O3 at room temperature limits the amount of carbon corrosion. Room temperature O3 treatment of poisoned fuel cell stacks may offer an efficient and quick remediation method to recover otherwise inoperable systems.

  1. High Modulus, High Conductivity Nanostructured Polymer Electrolyte Membranes via Polymerization-Induced Phase Separation

    Science.gov (United States)

    McIntosh, Lucas; Schulze, Morgan; Hillmyer, Marc; Lodge, Timothy

    2014-03-01

    Solvent-free, solid-state polymer electrolyte membranes (PEMs) will play a vital role in next-generation electrochemical devices such as Li-metal batteries and high- T fuel cells. The primary challenge is that these applications require PEMs with substantial mechanical robustness, as well as high ionic conductivity. The key to optimizing orthogonal macroscopic properties is to use a heterogeneous composite with well-defined nanoscopic morphology--specifically, long-range co-continuity of high modulus and ion transport domains, which has proven difficult to achieve in commonly-studied diblock copolymer-based electrolytes. We report a simple synthetic strategy to generate PEMs via polymerization-induced phase separation, where the delicate balance between controlled addition of styrene onto a poly(ethylene oxide) macro-chain transfer agent and simultaneous chemical crosslinking by divinylbenzene results in a disordered structure with domain size of order 10 nm. Crucially, both domains exhibit long-range continuity, which results in PEMs that are glassy solids (modulus ~ 1 GPa) owing to the isotropic network of stiff, crosslinked polystyrene, and are highly conductive (> 1 mS/cm at 70 °C) because ions migrate in channels of low Tg poly(ethylene oxide).

  2. Carbon-coated ceramic membrane reactor for the production of hydrogen by aqueous-phase reforming of sorbitol.

    Science.gov (United States)

    Neira D'Angelo, M F; Ordomsky, V; Schouten, J C; van der Schaaf, J; Nijhuis, T A

    2014-07-01

    Hydrogen was produced by aqueous-phase reforming (APR) of sorbitol in a carbon-on-alumina tubular membrane reactor (4 nm pore size, 7 cm long, 3 mm internal diameter) that allows the hydrogen gas to permeate to the shell side, whereas the liquid remains in the tube side. The hydrophobic nature of the membrane serves to avoid water loss and to minimize the interaction between the ceramic support and water, thus reducing the risks of membrane degradation upon operation. The permeation of hydrogen is dominated by the diffusivity of the hydrogen in water. Thus, higher operation temperatures result in an increase of the flux of hydrogen. The differential pressure has a negative effect on the flux of hydrogen due to the presence of liquid in the larger pores. The membrane was suitable for use in APR, and yielded 2.5 times more hydrogen than a reference reactor (with no membrane). Removal of hydrogen through the membrane assists in the reaction by preventing its consumption in undesired reactions.

  3. Structural Transitions in Dense Networks

    CERN Document Server

    Lambiotte, R; Bhat, U; Redner, S

    2016-01-01

    We introduce an evolving network model in which a new node attaches to a randomly selected target node and also to each of its neighbors with probability $p$. The resulting network is sparse for $p<\\frac{1}{2}$ and dense (average degree increasing with number of nodes $N$) for $p\\geq \\frac{1}{2}$. In the dense regime, individual networks realizations built by this copying mechanism are disparate and not self-averaging. Further, there is an infinite sequence of structural anomalies at $p=\\frac{2}{3}$, $\\frac{3}{4}$, $\\frac{4}{5}$, etc., where the dependences on $N$ of the number of triangles (3-cliques), 4-cliques, undergo phase transitions. When linking to second neighbors of the target can occur, the probability that the resulting graph is complete---where all nodes are connected---is non-zero as $N\\to\\infty$.

  4. Enrichment and identification of integral membrane proteins from barley aleurone layers by reversed-phase chromatography, SDS-PAGE, and LC-MS/MS

    DEFF Research Database (Denmark)

    Hynek, Radovan; Svensson, Birte; Jensen, O.N.

    2006-01-01

    The plasma membrane of the cereal aleurone layer is the site of perception of germination signals and release of enzymes to the starchy endosperm. Analysis of membrane proteins is challenging due to their hydrophobicity and low abundance; thus, little is known about the membrane proteins involved...... in seed germination. A membrane fraction highly enriched for the plasma membrane H+-ATPase was prepared from barley aleurone layers by aqueous two-phase partitioning. Because detergent and salt washes did not efficiently remove soluble proteins from the membrane preparations, an alternative procedure...... membrane proteins with relatively low levels of soluble contaminating proteins. Forty-six proteins associated with barley aleurone plasma membranes were identified, including proteins with more than 10 transmembrane domains. Among the identified proteins were two new isoforms of the plasma membrane H...

  5. Enrichment and identification of integral membrane proteins from barley aleurone layers by reversed-phase chromatography, SDS-PAGE and LC-MS/MS

    DEFF Research Database (Denmark)

    Hynek, Radovan; Svensson, Birte; Nørregaard Jensen, Ole

    2006-01-01

    The plasma membrane of the cereal aleurone layer is the site of perception of germination signals and release of enzymes to the starchy endosperm. Analysis of membrane proteins is challenging due to their hydrophobicity and low abundance, thus little is known about the membrane proteins involved...... in seed germination. A membrane fraction highly enriched for the plasma membrane H+-ATPase was prepared from barley aleurone layers by aqueous two-phase partitioning. Since detergent and salt washes did not efficiently remove soluble proteins from the membrane preparations, an alternative procedure...... membrane proteins with relatively low levels of soluble contaminating proteins. Forty-six proteins associated with barley aleurone plasma membranes were identified, including proteins with more than 10 transmembrane domains. Among the identified proteins were two new isoforms of the plasma membrane H...

  6. Dual-Phase Oxygen Transport Membranes for Stable Operation in Environments Containing Carbon Dioxide and Sulfur Dioxide.

    Science.gov (United States)

    Garcia-Fayos, Julio; Balaguer, María; Serra, José M

    2015-12-21

    Dual-phase membranes are appealing candidates for oxygen transport membranes owing to their unique combination of ambipolar electron-ion transport and endurance. However, O2 separation in industrial environments demands very high stability and effectiveness in the presence of CO2- and SO2-bearing process gases. Here, the composition of dual-phase membranes based on NiFe2O4-Ce(0.8) Tb(0.2)O(2-δ) (NFO-CTO) was optimized and the effective performance of catalytically-activated membranes was assessed in presence of CO2 and SO2. Further insight into the limiting mechanisms in the permeation was gained through electrical conductivity studies, permeation testing in several conditions and impedance spectroscopy analysis. The dual-phase membranes were prepared by one-pot sol-gel method and their permeability increases with increasing fluorite content. An O2 flux of 0.25 (ml min(-1)  cm(-2)) mm at 1000 °C was obtained for a thick self-standing membrane with 40:60 NFO/CTO composition. An in-depth study mimicking typical harsh conditions encountered in oxyfuel flue gases was performed on a 50:50 NFO/CTO membrane. CO2 content as well as SO2 presence in the sweep gas stream were evaluated in terms of O2 permeation. O2 fluxes of 0.13 and 0.09 mL min(-1)  cm(-2) at 850 °C were obtained for a 0.59 mm thick membrane under CO2 and 250 ppm SO2 in CO2 sweep conditions, respectively. Extended periods at work under CO2- and SO2-containing atmospheres revealed good permeation stability over time. Additionally, XRD, backscattered electrons detector (BSD)-SEM, and energy-dispersive X-ray spectroscopy (EDS) analysis of the spent membrane confirmed material stability upon prolonged exposure to SO2.

  7. A Physical Model to Study the Effects of Nozzle Design on Dense Two-Phase Flows in a Slab Mold Casting Ultra-Low Carbon Steels

    Science.gov (United States)

    Salazar-Campoy, María M.; Morales, R. D.; Nájera-Bastida, A.; Cedillo-Hernández, Valentín; Delgado-Pureco, J. C.

    2017-01-01

    Momentum transfer of argon-steel flows in a slab mold were studied through an air-water physical model and particle image velocimetry measurements under the effects of nozzle design (nozzles with square ports S, square ports with bottom design U and circular ports C) and gas flow rate. The ratio of drag momentum of the gas phase over the liquid phase defines the conditions for coupled (existence of momentum transfer between the phases) and channeled flows (defined as those conditions where there is not further momentum transfer between both phases). When the ratio of superficial velocities of the gas phase over the liquid phase in the nozzle bore is less than 0.14, the flow pattern in the mold is dependent on the nozzle design and flow rate of gas (2 to 10 L/minute). Above this magnitude, the flow pattern becomes uncoupled and independent from the nozzle design and from the flow rate of gas. The ratios of drag velocities of the gas phase on the liquid phase and their superficial velocities in the nozzle bore are strongly dependent on the volume fraction of the gas phase. Nozzle U delivers the smallest sizes of bubbles and the smaller amount of bubble swarms per unit time impacting on the narrow face of the mold. It is, therefore, the most recommendable to cast ultra-low carbon steels. Practical implications derived from these results are written down in the text.

  8. Measurement and Analysis of Bath-Side Interfacial Concentration Gradients during Membrane Quenching by Phase Inversion.

    Science.gov (United States)

    Gaides, Gary Edward

    A technique based on Fourier transform optical theory has been developed which allows for transient measurements of bath-side interfacial refractive index gradients during the quench step of membrane formation by phase inversion. From examination of individual Fourier components in a diffraction pattern associated with this one-dimensional mass transport process one is able to overcome the temporal and spatial resolution limitations imposed by many of the more traditional optical techniques. A first order expression relating the local refractive index gradient in the quench cell as a function of its measured spatial offset in the Fourier plane was derived for the purpose of determining the interfacial gradient which may be readily converted to individual species (solvent/nonsolvent) concentration gradients. Real-time interfacial gradients were able to be measured anywhere from 2 to 5 seconds after initiation of the quench using this technique. The r.m.s. errors associated with the reported interfacial species concentration gradient values were determined to range between 3% and 7% of the reported values for quench times less than 60 seconds. However, the reproducability of the experiment was shown to be well within these error limits. The bath-side interfacial refractive index gradient was measured as a function of time for both delayed (cellulose acetate in N,N-dimethylformamide with added nonsolvent ethanol) and instantaneous (cellulose acetate or polysulfone in N,N-dimethylformamide with added nonsolvent water) phase separation conditions with allowed variability in the following processing conditions: initial cast film thickness, initial solvent composition in the coagulation bath, initial nonsolvent composition in the casting solution, and initial polymer concentration in the casting solution. The directionality of the change associated with experimentally observed phenomena (bath-side interfacial solvent gradient and the time at which phase separation occurs

  9. Chemical composition and structural phase changes of Pd sample and properties of novel synthesized structure at dense deuterium gas under irradiation by γ-quanta

    Science.gov (United States)

    Didyk, A. Yu.; Wiśniewski, R.

    2012-12-01

    Studies have been carried out into the element composition of Pd and brass with associated materials and synthesized novel structure, placed in dense deuterium gas in a deuterium high-pressure chamber (DHPC) under the pressure 3 kbar and irradiated with γ-quanta of energy up to 8.8 MeV. Using the methods of scanning electron microscopy, microelement chemical analysis and X-ray diffraction, it was determined that in the absence in the chamber volume and walls of all HPC-forming materials the synthesized structure is largely composed of alumosilicates and Al and Si oxides with high content of Ti compounds as rutile TiO2. Pd1.5D2. Considerable anomalies in the chemical composition were found both in the surface and at large depth in a Pd specimen. The entire Pd surface turned into a structure comprised of Pd clusters, Cu and Zn compounds, with a notable content of Mg, Al, S, Si, K, Ca, Ti and Fe compounds. Results of evaluative calculations, including computation of the Q-value, are presented for nuclear reactions produced in a saturated with deuterium Pd specimen and dense deuterium gas under the action of γ-quanta, neutrons and protons of energies up to E n + E p ≈ E γ - E D MeV generated by deuteron fission. The obtained results can be explained by "collective effects" as chain reactions caused by deuteron fission induced by protons ( E p > 3.39 MeV) and neutrons ( E n > 2.25 MeV), as well as by thermonuclear synthesis of deuterium atoms elastically scattered by protons of energies up to E P < E γ - E D MeV.

  10. Mechanisms and modeling development of water transport/phase change in catalyst layers of portion exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Yexiang [Dept. of Thermal Engineering, Tsinghua University Beijing (China)], email: Yexiang.Xiao@energy.lth.se; Yuan, Jinliang; Sunden, Bengt [Dept. of Energy Sciences, Faculty of Engineering, Lund University (Sweden)], email: Jinliang.yuan@energy.lth.se, email: bengt.sunden@energy.lth.se

    2011-07-01

    Research on proton exchange membrane fuel cells has shown that incorporation of nanosized catalysts can effectively increase active areas and catalyst activity and make a great contribution to development in performance and catalyst utilization. Multiphase transport processes are as significant and complicated as water generation/transfer processes which occur in nano-structured catalyst layers. A review project has been launched aimed at gaining a comprehensive understanding of the mechanisms of water generation or transport phenomena. It covers catalytic reactions and water-phase change within the catalyst layers. The review proceeds in three main stages: Firstly, it characterizes and reconstructs the nano/micro-structured pores and solid-phases; secondly, it emphasises the importance of sensitive and consistent analysis of various water-phase change and transport schemes; and thirdly, it recommends development of microscopic models for multi-phase transport processes in the pores and the solid phases.

  11. Phenolic wastewater treatment through extractive recovery coupled with biodegradation in a two-phase partitioning membrane bioreactor.

    Science.gov (United States)

    Praveen, Prashant; Loh, Kai-Chee

    2015-12-01

    A two-phase partitioning membrane bioreactor (TPPMB) was designed and operated for treatment of high strength phenolic wastewater through extraction/stripping and concomitant biodegradation. Tributyl phosphate dissolved in kerosene was used as the organic phase, sodium hydroxide as the stripping phase and Pseudomonas putida for biodegradation. In a semi-dispersive approach, organic phase dispersed in the stripping solution was contacted with wastewater through semi-permeable membranes for removal of phenol from wastewater, while the microorganisms were inoculated directly into the wastewater for biodegradation. The TPPMB exhibited high phenol removal rates, and phenol concentrations of 1000-3000mg/L were reduced to undetected amounts within 2-4h. Up to 80% phenol was recovered through extraction, while the remaining was metabolized by the microorganisms. Phenol recovery in the TPPMB was enhanced by increasing the mass transfer rate of phenol through the membranes, and it was also estimated that phenol diffusion through the aqueous boundary layer on the tube side was the rate limiting step. The flexibility in adjusting inoculation time in the TPPMB prevented microorganisms from adverse effects of substrate inhibition, which facilitated complete removal of phenol from the wastewater. TPPMB retained the advantages of both solvent extraction and biodegradation, and it can be highly promising for the treatment of toxic industrial wastewater.

  12. Water Transport in Bicontinuous, Phase-Separated Membranes Made from Reactive Block Copolymers

    Science.gov (United States)

    2014-12-01

    1.7, Tokuyama A201, and Nexar MD9200 membranes at 35 °C. The gray line represents the typical sweat production for a Soldier performing at a medium...concentrated via rotary evaporation and precipitated into diethyl ether . The resulting yellow solid was washed with ether , redissolved into ethanol...membranes were then peeled from the surface and washed with water, acetone, ethyl acetate, acetone, and finally water. Membranes were then immersed in

  13. Effect of integral proteins in the phase stability of a lipid bilayer: Application to raft formation in cell membranes

    Science.gov (United States)

    Gómez, Jordi; Sagués, Francesc; Reigada, Ramon

    2010-04-01

    The existence of lipid rafts is a controversial issue. The affinity of cholesterol for saturated lipids is manifested in macroscopic phase separation in model membranes, and is believed to be the thermodynamic driving force for raft formation. However, there is no clear reason to explain the small (nanometric) size of raft domains in cell membranes. In a recent paper Yethiraj and Weisshaar [Biophys. J. 93, 3113 (2007)] proposed that the effect of neutral integral membrane proteins may prevent from the formation of large lipid domains. In this paper we extend this approach by studying the effect of the protein size, as well as the lipid-protein interaction. Depending on these factors, two different mechanisms for nanodomain stabilization are shown to be possible for static proteins. The application of these results to a biological context is discussed.

  14. Effects of Low Concentrations of Docosahexaenoic Acid on the Structure and Phase Behavior of Model Lipid Membranes

    Directory of Open Access Journals (Sweden)

    Chai Lor

    2015-12-01

    Full Text Available In this paper we report an X-ray diffraction study on the phase behavior of binary lipid mixtures of 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (DHA-PE and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC at low concentrations below 5.0 mol% DHA-PE. Our results show that DHA-PE induces phase separation into a DHA rich liquid crystalline (Lα phase and a DHA poor gel (Lβ′ phase at overall DHA-PE concentrations as low as 0.1 mol%. In addition, we find that the structure of the Lβ′ phase, from which the DHA-PE molecules are largely excluded, is modified in the phase-separated state at low DHA-PE concentrations, with a decrease in bilayer thickness of 1.34 nm for 0.1 mol% at room temperature, compared to pure DPPC bilayers. This result is contrary to that seen in similar studies on mono-unsaturated lipids where an increase in bilayer thickness is observed. The surprising effect of such low DHA-PE concentrations on membrane structure may be important in understanding the role of highly polyunsaturated lipids in biological membrane-based structures and similar artificial surfactant systems.

  15. Topical dorzolamide for macular edema in the early phase after vitrectomy and epiretinal membrane removal

    Directory of Open Access Journals (Sweden)

    Suzuki T

    2013-04-01

    /ms and the control group (467.8 µm, 64.0 pc/ms. Differences in mean intraocular pressure preoperatively and at 2 weeks, 1 month, and 3 months after surgery were not statistically significant between the two groups. Intraocular pressure never exceeded 21 mmHg.Conclusion: Topical dorzolamide significantly reduced mean central macular thickness at 1 month and mean aqueous flare at 2 weeks after surgery for epiretinal membrane compared with controls. Although further investigation of more cases and longer follow-up are needed, this study suggests that topical dorzolamide can be efficacious in reducing macular edema in the early phase after vitrectomy via its anti-inflammatory effect.Keywords: macular edema, dorzolamide, epiretinal membrane, vitrectomy, anti-inflammatory

  16. meta-DENSE complex acquisition for reduced intravoxel dephasing

    Science.gov (United States)

    Aletras, Anthony H.; Arai, Andrew E.

    2004-08-01

    Displacement encoding with stimulated echoes (DENSE) with a meta-DENSE readout and RF phase cycling to suppress the STEAM anti-echo is described for reducing intravoxel dephasing signal loss. This RF phase cycling scheme, when combined with existing meta-DENSE suppression of the T1 recovering signal, yields higher quality DENSE myocardial strain maps. Phantom and human images are provided to demonstrate the technique, which is capable of acquiring phase contrast displacement encoded images at low encoding gradient strengths providing better spatial resolution and less signal loss due to intravoxel dephasing than prior methods.

  17. Line tension at lipid phase boundaries regulates formation of membrane vesicles in living cells

    DEFF Research Database (Denmark)

    Vind-Kezunovic, D.; Nielsen, C.H.; Wojewodzka, U.;

    2008-01-01

    fluorescein-labeled cholera toxin B subunit which labels ganglioside GM(1) enriched plasma membrane rafts. Cholesterol depletion with methyl-beta-cyclodextrin enhanced DiI vesiculation, GM(1)/DiI domain separation and was accompanied by a detachment of the subcortical cytoskeleton from the plasma membrane...

  18. Line tension at lipid phase boundaries regulates formation of membrane vesicles in living cells

    DEFF Research Database (Denmark)

    Vind-Kezunovic, Dina; Helix Nielsen, Claus; Wojewodzka, Urszula;

    2008-01-01

    -labeled cholera toxin B subunit which labels ganglioside GM(1) enriched plasma membrane rafts. Cholesterol depletion with methyl-beta-cyclodextrin enhanced DiI vesiculation, GM(1)/DiI domain separation and was accompanied by a detachment of the subcortical cytoskeleton from the plasma membrane. Based...

  19. Relationship between erythrocyte membrane phase properties and susceptibility to secretory phospholipase A2.

    Science.gov (United States)

    Best, Katrina B; Ohran, Allison J; Hawes, Andrea C; Hazlett, Theodore L; Gratton, Enrico; Judd, Allan M; Bell, John D

    2002-11-26

    Normally, cell membranes resist hydrolysis by secretory phospholipase A(2). However, upon elevation of intracellular calcium, the cells become susceptible. Previous investigations demonstrated a possible relationship between changes in lipid order caused by increased calcium and susceptibility to phospholipase A(2). To further explore this relationship, we used temperature as an experimental means of manipulating membrane physical properties. We then compared the response of human erythrocytes to calcium ionophore at various temperatures in the range of 20-50 degrees C using fluorescence spectroscopy and two-photon fluorescence microscopy. The steady state fluorescence emission of the environment-sensitive probe, laurdan, revealed that erythrocyte membrane order decreases systematically with temperature throughout this range, especially between 28 and 45 degrees C. Furthermore, the ability of calcium ionophore to induce increased membrane order and susceptibility to phospholipase A(2) depended similarly on temperature. Both responses to calcium influx were enhanced as membrane fluidity increased. Analysis of the spatial distribution of laurdan fluorescence at several temperatures indicated that the ordering effect of intracellular calcium on fluid membranes generates an increase in the number of fluid-solid boundaries. Hydrolysis of the membrane appeared to progress outward from these boundaries. We conclude that phospholipase A(2) prefers to hydrolyze lipids in fluid regions of human erythrocyte membranes, but primarily when those regions coexist with domains of ordered lipids.

  20. Trans-complex formation by proteolipid channels in the terminal phase of membrane fusion

    DEFF Research Database (Denmark)

    Peters, C; Bayer, M J; Bühler, S

    2001-01-01

    +/calmodulin controls this terminal process in many intracellular fusion events. Here we identify V0, the membrane-integral sector of the vacuolar H+-ATPase, as a target of calmodulin on yeast vacuoles. Between docking and bilayer fusion, V0 sectors from opposing membranes form complexes. V0 trans...

  1. Numerical simulation of the phase separation in binary lipid membrane under the effect of stationary shear flow.

    Science.gov (United States)

    Chen, Xiao-Bo; Niu, Li-Sha; Shi, Hui-Ji

    2008-06-01

    A numerical simulation of the phase separation in binary lipid membrane under the effect of stationary shear flow is performed. We numerically solved the modified two-dimensional time-dependent Ginzburg-Landau (TDGL) equations with an external velocity term, employing the CDS (i.e., Cell Dynamical System) technique. In the present simulation, stationary shear flows with different shear rates are taken into account. The evolution process of the phase separation is illustrated macroscopically via the snapshot figures and simulated scattering patterns at several typical moments. For each case, the growth exponents of the characteristic domain sizes in both directions parallel and perpendicular to the flow are studied, and the domain area as well. Also, the behavior of the excess viscosity has been investigated, which is a peculiar rheological indicator of such a membrane system with domain structures.

  2. 60 Hz electric field changes the membrane potential during burst phase in pancreatic β-cells: in silico analysis.

    Science.gov (United States)

    Neves, Gesilda F; Silva, José R F; Moraes, Renato B; Fernandes, Thiago S; Tenorio, Bruno M; Nogueira, Romildo A

    2014-06-01

    The production, distribution and use of electricity can generate low frequency electric and magnetic fields (50-60 Hz). Considering that some studies showed adverse effects on pancreatic β-cells exposed to these fields; the present study aimed to analyze the effects of 60 Hz electric fields on membrane potential during the silent and burst phases in pancreatic β-cells using a mathematical model. Sinusoidal 60 Hz electric fields with amplitude ranging from 0.5 to 4 mV were applied on pancreatic β-cells model. The sinusoidal electric field changed burst duration, inter-burst intervals (silent phase) and spike sizes. The parameters above presented dose-dependent response with the voltage amplitude applied. In conclusion, theoretical analyses showed that a 60 Hz electric field with low amplitudes changes the membrane potential in pancreatic β-cells.

  3. Warm Dense Matter: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Kalantar, D H; Lee, R W; Molitoris, J D

    2004-04-21

    This document provides a summary of the ''LLNL Workshop on Extreme States of Materials: Warm Dense Matter to NIF'' which was held on 20, 21, and 22 February 2002 at the Wente Conference Center in Livermore, CA. The warm dense matter regime, the transitional phase space region between cold material and hot plasma, is presently poorly understood. The drive to understand the nature of matter in this regime is sparking scientific activity worldwide. In addition to pure scientific interest, finite temperature dense matter occurs in the regimes of interest to the SSMP (Stockpile Stewardship Materials Program). So that obtaining a better understanding of WDM is important to performing effective experiments at, e.g., NIF, a primary mission of LLNL. At this workshop we examined current experimental and theoretical work performed at, and in conjunction with, LLNL to focus future activities and define our role in this rapidly emerging research area. On the experimental front LLNL plays a leading role in three of the five relevant areas and has the opportunity to become a major player in the other two. Discussion at the workshop indicated that the path forward for the experimental efforts at LLNL were two fold: First, we are doing reasonable baseline work at SPLs, HE, and High Energy Lasers with more effort encouraged. Second, we need to plan effectively for the next evolution in large scale facilities, both laser (NIF) and Light/Beam sources (LCLS/TESLA and GSI) Theoretically, LLNL has major research advantages in areas as diverse as the thermochemical approach to warm dense matter equations of state to first principles molecular dynamics simulations. However, it was clear that there is much work to be done theoretically to understand warm dense matter. Further, there is a need for a close collaboration between the generation of verifiable experimental data that can provide benchmarks of both the experimental techniques and the theoretical capabilities

  4. Two phase flow simulation in a channel of a polymer electrolyte membrane fuel cell using the lattice Boltzmann method

    OpenAIRE

    Ben Salah, Yasser; Tabe, Yutaka; Chikahisa, Takemi

    2012-01-01

    Water management in polymer electrolyte (PEM) fuel cells is important for fuel cell performance and durability. Numerical simulations using the lattice Boltzmann method (LBM) are developed to elucidate the dynamic behavior of condensed water and gas flows in a polymer electrolyte membrane (PEM) fuel cell gas channel. A scheme for two-phase flow with large density differences was applied to establish the optimum gas channel design for different gas channel heights, droplet positions, and gas c...

  5. Fabrication of highly co2 selective metal organic framework membrane using liquid phase epitaxy approach

    KAUST Repository

    Eddaoudi, Mohamed

    2016-01-28

    Embodiments include a method of making a metal organic framework membrane comprising contacting a substrate with a solution including a metal ion and contacting the substrate with a solution including an organic ligand, sufficient to form one or more layers of a metal organic framework on a substrate. Embodiments further include a defect-free metal organic framework membrane comprising MSiF6(pyz)2, wherein M is a metal, wherein the thickness of the membrane is less than 1,000 µm, and wherein the metal organic has a growth orientation along the [110] plane relative to a substrate.

  6. LIPID RAFTS, FLUID/FLUID PHASE SEPARATION, AND THEIR RELEVANCE TO PLASMA MEMBRANE STRUCTURE AND FUNCTION

    OpenAIRE

    Sengupta, Prabuddha; Baird, Barbara; Holowka, David

    2007-01-01

    Novel biophysical approaches combined with modeling and new biochemical data have helped to recharge the lipid raft field and have contributed to the generation of a refined model of plasma membrane organization. In this review, we summarize new information in the context of previous literature to provide new insights into the spatial organization and dynamics of lipids and proteins in the plasma membrane of live cells. Recent findings of large-scale separation of liquid-ordered and liquid-di...

  7. Modelling dense relational data

    DEFF Research Database (Denmark)

    Herlau, Tue; Mørup, Morten; Schmidt, Mikkel Nørgaard;

    2012-01-01

    Relational modelling classically consider sparse and discrete data. Measures of influence computed pairwise between temporal sources naturally give rise to dense continuous-valued matrices, for instance p-values from Granger causality. Due to asymmetry or lack of positive definiteness they are no......Relational modelling classically consider sparse and discrete data. Measures of influence computed pairwise between temporal sources naturally give rise to dense continuous-valued matrices, for instance p-values from Granger causality. Due to asymmetry or lack of positive definiteness...... they are not naturally suited for kernel K-means. We propose a generative Bayesian model for dense matrices which generalize kernel K-means to consider off-diagonal interactions in matrices of interactions, and demonstrate its ability to detect structure on both artificial data and two real data sets....

  8. A Continuum Model for Water Transport in the Ionomer-Phase of Catalyst Coated Membranes for PEMFCs

    Directory of Open Access Journals (Sweden)

    Vladimir Gurau

    2010-01-01

    Full Text Available We study the problem of water transport in the ionomer-phase of catalyst coated membranes (CCMs for proton exchange membrane fuel cells (PEMFCs, where microscopic-scale phenomena at the distributed interfaces between structural components control the water management. Existing models for water transport in CCMs describe the transport in systems which consist exclusively of an ionomer-phase. Interfacial water fluxes across distributed interfaces representing various mechanisms of water transfer between ionomer and catalyst layer pores are not captured properly in these models. Here we develop a continuum model for water transport in CCMs using the method of volume averaging. Water is exchanged between ionomer and the catalyst layer pores by electro-osmotic discharge (EOD through the three-phase boundary (TPB regions and by sorption and desorption across the ionomer-pore interfaces. While the former mechanism does not affect directly the water content in the ionomer-phase, it represents an effective mechanism for water transfer during fuel cell operation and controls directly the water saturation in the catalyst pores.

  9. Facile fabrication of ultrathin hybrid membrane for highly flexible supercapacitors via in-situ phase separation of polyethersulfone

    Science.gov (United States)

    Zhao, Xiaoning; Ran, Fen; Shen, Kuiwen; Yang, Yunlong; Wu, Jiayu; Niu, Xiaoqin; Kong, Lingbin; Kang, Long; Chen, Shaowei

    2016-10-01

    In this article, a facile method based on in-situ phase-separation was developed for the fabrication of ultrathin hybrid membranes for highly flexible supercapacitors. The structures and morphologies of the prepared electrodes were characterized by scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) measurements; and the electrochemical behaviors were examined in 2 M KOH solution. SEM and FTIR characterizations reveal that activated carbon was imbedded into the polymer membrane of polyethersulfone to form a uniform and flexible hybrid membrane. When the thin polymer-carbon membrane (PCM) was used as an electrode material for supercapacitor, a high specific capacitance of 169.4 Fg-1 was obtained at a current density of 0.5 Ag-1 along with good long-term cycle life of 94.6% capacity retention after 2000 charging-discharging cycles. Benefiting from these merits, the as-fabricated PCM//PCM cell shows an excellent electrochemical property. These results suggest a promising route towards the fabrication of highly flexible electrodes for high-performance supercapacitors.

  10. Dynamic single-interface hollow fiber liquid phase microextraction of Cr(VI) using ionic liquid containing supported liquid membrane.

    Science.gov (United States)

    Pimparu, Rungaroon; Nitiyanontakit, Sira; Miró, Manuel; Varanusupakul, Pakorn

    2016-12-01

    The concept of dynamic single-interface hollow fiber membrane liquid-phase microextraction (HF-LPME), where the target analyte was extracted on-line and eluted inside the lumen of the HF membrane, was explored. An ionic liquid containing supported liquid membrane was used for the trace determination of Cr(VI) as a model compound. Since the extraction took place on-line inside the hollow fiber membrane, the mass transfer behavior was described and discussed in comparison with the conventional HF-LPME. The extraction efficiency was improved by a recirculation configuration of the sample solution at relatively high sampling flow rates as a result of the increased effective contact area. The positive pressure observed to be built up during extraction was overcome by a flow-balancing pressure design. The dynamic single-interface HF-LPME method with an enrichment factor of 41, a detection limit of 1.2µgL(-1) and determination limit of 4.0µgL(-1) was successfully applied to the reliable determination of Cr(VI) from environmental water samples. The quantification limit is below the maximum contaminant level in drinking water, set at 10µgL(-1) of hexavalent chromium by the California Environmental Protection Agency.

  11. Three-dimensional two-phase flow model of proton exchange membrane fuel cell with parallel gas distributors

    Science.gov (United States)

    Liu, Xunliang; Lou, Guofeng; Wen, Zhi

    A non-isothermal, steady-state, three-dimensional (3D), two-phase, multicomponent transport model is developed for proton exchange membrane (PEM) fuel cell with parallel gas distributors. A key feature of this work is that a detailed membrane model is developed for the liquid water transport with a two-mode water transfer condition, accounting for the non-equilibrium humidification of membrane with the replacement of an equilibrium assumption. Another key feature is that water transport processes inside electrodes are coupled and the balance of water flux is insured between anode and cathode during the modeling. The model is validated by the comparison of predicted cell polarization curve with experimental data. The simulation is performed for water vapor concentration field of reactant gases, water content distribution in the membrane, liquid water velocity field and liquid water saturation distribution inside the cathode. The net water flux and net water transport coefficient values are obtained at different current densities in this work, which are seldom discussed in other modeling works. The temperature distribution inside the cell is also simulated by this model.

  12. Effect of Extractant and Cold-drawing on the Structure and Performance of HDPE Hollow Fiber Membranes Fabricated via Thermally Induced Phase Separation Method

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-li; RUAN Wen-xiang; SONG Yi-lin; JI Jian-bing; YAO Ke-jian

    2006-01-01

    Microporous polyolefin hollow fiber membranes were prepared from high density polyethylene (HDPE)-paraffin solution via thermally induced phase separation (TIPS)method. Effects of extraction and cold-drawing condition on membrane structure and performance were investigated.Five volatile solvents were used as extractant. Dimension of hollow fiber and gas permeation rate of membrane were measured. Microstructure of membrane was examined by Scanning Electronic Microscope (SEM). The results show that the membrane treated by pentane possesses a higher porosity, nitrogen permeability and lower shrinkage than those of membranes extracted by other three extractants. It is also found that thc membrane stretched 133% shows the highest porosity and gas permeability in this study.

  13. Enrichment and identification of integral membrane proteins from barley aleurone layers by reversed-phase chromatography, SDS-PAGE, and LC-MS/MS

    DEFF Research Database (Denmark)

    Hynek, Radovan; Svensson, Birte; Jensen, O.N.

    2006-01-01

    The plasma membrane of the cereal aleurone layer is the site of perception of germination signals and release of enzymes to the starchy endosperm. Analysis of membrane proteins is challenging due to their hydrophobicity and low abundance; thus, little is known about the membrane proteins involved...... in seed germination. A membrane fraction highly enriched for the plasma membrane H+-ATPase was prepared from barley aleurone layers by aqueous two-phase partitioning. Because detergent and salt washes did not efficiently remove soluble proteins from the membrane preparations, an alternative procedure......+-ATPase, two proteins possibly involved in ion-channel regulation, and two proteins of unknown function. This represents the first analysis of membrane proteins involved in seed germination using a proteomics approach....

  14. Influences of membrane properties on phase response curve and synchronization stability in a model globus pallidus neuron.

    Science.gov (United States)

    Fujita, Tomohiro; Fukai, Tomoki; Kitano, Katsunori

    2012-06-01

    The activity patterns of the globus pallidus (GPe) and subthalamic nucleus (STN) are closely associated with motor function and dysfunction in the basal ganglia. In the pathological state caused by dopamine depletion, the STN-GPe network exhibits rhythmic synchronous activity accompanied by rebound bursts in the STN. Therefore, the mechanism of activity transition is a key to understand basal ganglia functions. As synchronization in GPe neurons could induce pathological STN rebound bursts, it is important to study how synchrony is generated in the GPe. To clarify this issue, we applied the phase-reduction technique to a conductance-based GPe neuronal model in order to derive the phase response curve (PRC) and interaction function between coupled GPe neurons. Using the PRC and interaction function, we studied how the steady-state activity of the GPe network depends on intrinsic membrane properties, varying ionic conductances on the membrane. We noted that a change in persistent sodium current, fast delayed rectifier Kv3 potassium current, M-type potassium current and small conductance calcium-dependent potassium current influenced the PRC shape and the steady state. The effect of those currents on the PRC shape could be attributed to extension of the firing period and reduction of the phase response immediately after an action potential. In particular, the slow potassium current arising from the M-type potassium and the SK current was responsible for the reduction of the phase response. These results suggest that the membrane property modulation controls synchronization/asynchronization in the GPe and the pathological pattern of STN-GPe activity.

  15. A fresh look at dense hydrogen under pressure. IV. Two structural models on the road from paired to monatomic hydrogen, via a possible non-crystalline phase.

    Science.gov (United States)

    Labet, Vanessa; Hoffmann, Roald; Ashcroft, N W

    2012-02-21

    In this paper, we examine the transition from a molecular to monatomic solid in hydrogen over a wide pressure range. This is achieved by setting up two models in which a single parameter δ allows the evolution from a molecular structure to a monatomic one of high coordination. Both models are based on a cubic Bravais lattice with eight atoms in the unit cell; one belongs to space group Pa3, the other to space group R3m. In Pa3 one moves from effective 1-coordination, a molecule, to a simple cubic 6-coordinated structure but through a very special point (the golden mean is involved) of 7-coordination. In R3m, the evolution is from 1 to 4 and then to 3 to 6-coordinate. If one studies the enthalpy as a function of pressure as these two structures evolve (δ increases), one sees the expected stabilization of minima with increased coordination (moving from 1 to 6 to 7 in the Pa3 structure, for instance). Interestingly, at some specific pressures, there are in both structures relatively large regions of phase space where the enthalpy remains roughly the same. Although the structures studied are always higher in enthalpy than the computationally best structures for solid hydrogen - those emerging from the Pickard and Needs or McMahon and Ceperley numerical laboratories - this result is suggestive of the possibility of a microscopically non-crystalline or "soft" phase of hydrogen at elevated pressures, one in which there is a substantial range of roughly equi-enthalpic geometries available to the system. A scaling argument for potential dynamic stabilization of such a phase is presented.

  16. From channel-forming ionic liquid crystals exhibiting humidity-induced phase transitions to nanostructured ion-conducting polymer membranes (adv. Mater. 26/2013).

    Science.gov (United States)

    Zhang, Heng; Li, Lei; Möller, Martin; Zhu, Xiaomin; Rueda, Jaime J Hernandez; Rosenthal, Martin; Ivanov, Dimitri A

    2013-07-12

    A novel wedge-shaped amphiphilic molecule bearing a sulfonate group at the tip displays humidity-induced phase transitions from a hexagonal columnar structure to a bicontinuous cubic phase. The mesophases can be frozen by photopolymerization of acrylic end-groups resulting in free-standing membranes with different topology of ionic nanochannels. The obtained membranes with a well-ordered ionic channel structure hold promise for applications in separation and catalysis.

  17. Experimental evaluation of enthalpy efficiency and gas-phase contaminant transfer in an enthalpy recovery unit with polymer membrane foils

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Yang, Jianrong; Fang, Lei

    2015-01-01

    and outdoor air by twin chambers was connected to the unit. Three chemical gases were dosed to the indoor exhaust air to mimic indoor air contaminants. Based on the measurements of temperature, humidity ratio, and contaminant concentrations of the indoor exhaust air and outdoor air supply upstream......Experimental studies were conducted in a laboratory setting to investigate the enthalpy efficiency and gas-phase contaminant transfer in a polymer membrane enthalpy recovery unit. One commercially available polymer membrane enthalpy recovery unit was used as a reference unit. Simulated indoor air...... and downstream of the unit, the temperature efficiencies, humidity efficiencies, enthalpy efficiencies, and contaminant transfer ratios were calculated. The results showed that over 60% of enthalpy recovery efficiency could be achieved and that the contaminant transfer ratios were in the range of 5.4% to 9...

  18. Solid-state membrane module

    Science.gov (United States)

    Gordon, John Howard; Taylor, Dale M.

    2011-06-07

    Solid-state membrane modules comprising at least one membrane unit, where the membrane unit has a dense mixed conducting oxide layer, and at least one conduit or manifold wherein the conduit or manifold comprises a dense layer and at least one of a porous layer and a slotted layer contiguous with the dense layer. The solid-state membrane modules may be used to carry out a variety of processes including the separating of any ionizable component from a feedstream wherein such ionizable component is capable of being transported through a dense mixed conducting oxide layer of the membrane units making up the membrane modules. For ease of construction, the membrane units may be planar.

  19. Geometric methods in the elastic theory of membranes in liquid crystal phases

    CERN Document Server

    Ji Xing Liu; Yu Zhang Xie

    1999-01-01

    This book contains a comprehensive description of the mechanical equilibrium and deformation of membranes as a surface problem in differential geometry. Following the pioneering work by W Helfrich, the fluid membrane is seen as a nematic or smectic - A liquid crystal film and its elastic energy form is deduced exactly from the curvature elastic theory of the liquid crystals. With surface variation the minimization of the energy at fixed osmotical pressure and surface tension gives a completely new surface equation in geometry that involves potential interest in mathematics. The investigations

  20. Studies of Phase Transitions and Critical Phenomena: I. Origin of Broken Particle-Hole Symmetry in Critical Fluids. I. Phase Transitions of Interacting Membranes.

    Science.gov (United States)

    Goldstein, Raymond Ethan

    The longstanding problem of the precise correspondence between critical phenomena in fluids and ferromagnets is resolved in Part I through a synthesis of mean field theory, exact results for lattice models, field-theoretic techniques, and by extensive quantitative comparison with experiment. Emphasis is placed on the origin of broken particle-hole symmetry in fluids as reflected in the form of the critical point scaling fields and in systematic variations in certain nonuniversal critical amplitudes with molecular polarizability. Those trends and the degree to which the scaling axes are linearly mixed versions of the bare "thermal" and "magnetic" fields in particle-hole symmetric systems are shown both for lattice models and real fluids to be intimately related to the presence of many-body interactions of the Axilrod-Teller type. A quantitatively accurate microscopic expression for the field-mixing operator of fluids is derived on the basis of an exact Hubbard-Stratonovich transformation relating the fluid Hamiltonian to that of a Landau-Ginzburg-Wilson model. A phenomenological theory of the phase behavior of multilamellar liquid crystals of hydrated phospholipid bilayers is developed in Part II, and its predictions tested by extensive comparison with experiment. A Ginzburg-Landau free energy functional based on the elastic properties of two coupled monolayers is proposed to describe intrabilayer ordering, and the phenomenon of structural phase transitions driven by membrane interactions is described by incorporating in addition the attractive dispersion interactions and repulsive "hydration" forces acting between membranes. The theory indicates and experiments support a connection between the pseudocriticality of the bilayer transitions and the large susceptibility of the in-plane order to membrane interactions. The pseudocriticality in turn is suggested to arise from the analog of a capillary critical point accessible by finite-size effects. Theoretical phase

  1. Phase coupling of a circadian neuropeptide with rest/activity rhythms detected using a membrane-tethered spider toxin.

    Directory of Open Access Journals (Sweden)

    Ying Wu

    2008-11-01

    Full Text Available Drosophila clock neurons are self-sustaining cellular oscillators that rely on negative transcriptional feedback to keep circadian time. Proper regulation of organismal rhythms of physiology and behavior requires coordination of the oscillations of individual clock neurons within the circadian control network. Over the last decade, it has become clear that a key mechanism for intercellular communication in the circadian network is signaling between a subset of clock neurons that secrete the neuropeptide pigment dispersing factor (PDF and clock neurons that possess its G protein-coupled receptor (PDFR. Furthermore, the specific hypothesis has been proposed that PDF-secreting clock neurons entrain the phase of organismal rhythms, and the cellular oscillations of other clock neurons, via the temporal patterning of secreted PDF signals. In order to test this hypothesis, we have devised a novel technique for altering the phase relationship between circadian transcriptional feedback oscillation and PDF secretion by using an ion channel-directed spider toxin to modify voltage-gated Na(+ channel inactivation in vivo. This technique relies on the previously reported "tethered-toxin" technology for cell-autonomous modulation of ionic conductances via heterologous expression of subtype-specific peptide ion channel toxins as chimeric fusion proteins tethered to the plasma membrane with a glycosylphosphatidylinositol (GPI anchor. We demonstrate for the first time, to our knowledge, the utility of the tethered-toxin technology in a transgenic animal, validating four different tethered spider toxin ion channel modifiers for use in Drosophila. Focusing on one of these toxins, we show that GPI-tethered Australian funnel-web spider toxin delta-ACTX-Hv1a inhibits Drosophila para voltage-gated Na(+ channel inactivation when coexpressed in Xenopus oocytes. Transgenic expression of membrane-tethered delta-ACTX-Hv1a in vivo in the PDF-secreting subset of clock neurons

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

    Energy Technology Data Exchange (ETDEWEB)

    Anand, M.; Ludwig, K.A.

    1996-04-01

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

  3. Racemic ofloxacin separation by supported-liquid membrane extraction with two organic phases

    Institute of Scientific and Technical Information of China (English)

    唐课文; 周春山; 蒋新宇

    2003-01-01

    Based on chemical thermodynamic theory, racemic ofloxacin is separatedin chiral systems by hollow fiber liquid-supported membrane technology combining with countercurrently fractional extraction. The two chiral solutions containing L-dibenzoyltartaric acid and D-dibenzoylta- rtaric acid in 1-octanol, flow through the lumen side and the shell side of fibers, respectively. The solution which flows through the lumen side of fibers also contains racemic ofloxacin. The wall of hollow fibers is filled with an aqueous of 0.1 mol/L Na2HPO4/H3PO4 buffer solution of pH = 6.86 containing 2 mmol/L of cetyltrimethyl ammonium bromide for 48 h. The fairly polar ofloxacin can cross the membrane back and forth, but dibenzoyltartaric acids cannot cross it. Fractional chiral extraction theory, mass transfer performance of hollow fiber membrane and enantioselectivity are investigated. Mathematical model of R/S = 0.96e0.03NTU for racemic ofloxacin separation by hollow fiber extraction, is established. The optical purity for ofloxacin enantiomers is up to 90% when 11 hollow fiber membrane modules of 22 cm in length in series are used.

  4. Improving gas separation properties of polymeric membranes based on glassy polymers by gas phase fluorination

    NARCIS (Netherlands)

    Syrtsova, D.A.; Kharitonov, A.P.; Teplyakov, V.V.; Koops, G.-H.

    2004-01-01

    The application area of existing gas separation membranes is limited by commercially available polymers for their preparation. In many cases the separation selectivity of these polymers is not sufficient for effective separation processes. One of the ways to improve the separation effectivity of exi

  5. Effect of membrane perturbants on the activity and phase distribution of inositol phosphorylceramide synthase; development of a novel assay.

    Science.gov (United States)

    Aeed, Paul A; Sperry, Andrea E; Young, Casey L; Nagiec, Marek M; Elhammer, Ake P

    2004-07-06

    The effect of 26 different membrane-perturbing agents on the activity and phase distribution of inositol phosphorylceramide synthase (IPC synthase) activity in crude Candida albicans membranes was investigated. The nonionic detergents Triton X-100, Nonidet P-40, Brij, Tween, and octylglucoside all inactivated the enzyme. However, at moderate concentrations, the activity of the Triton X-100- and octylglucoside-solubilized material could be partially restored by inclusion of 5 mM phosphatidylinositol (PI) in the solubilization buffer. The apparent molecular mass of IPC synthase activity solubilized in 2% Triton X-100 was between 1.5 x 10(6) and 20 x 10(6) Da, while under identical conditions, octylglucoside-solubilized activity remained associated with large presumably membrane-like structures. Increased detergent concentrations produced more drastic losses of enzymatic activity. The zwitterionic detergents Empigen BB, N-dodecyl-N,N-(dimethylammonio)butyrate (DDMAB), Zwittergent 3-10, and amidosulfobetaine (ASB)-16 all appeared capable of solubilizing IPC synthase. However, these agents also inactivated the enzyme essentially irreversibly. Solubilization with lysophospholipids again resulted in drastic losses of enzymatic activity that were not restored by the inclusion of PI. Lysophosphatidylinositol also appeared to compete, to some extent, with the donor substrate phosphatidylinositol. The sterol-containing agent digitonin completely inactivated IPC synthase. By contrast, sterol-based detergents such as 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO), and taurodeoxycholate (tDOC) had little or no effect on the enzyme activity. The IPC synthase activity in C. albicans membranes remained largely intact and sedimentable at CHAPS concentrations (4%) where >90% of the phospholipids and 60% of the total proteins were extracted from the membranes. At 2.5% CHAPS, a

  6. Recovery Of Chromium Metal (VI) Using Supported Liquid Membrane (SLM) Method, A study of Influence of NaCl and pH in Receiving Phase on Transport

    Science.gov (United States)

    Cholid Djunaidi, Muhammad; Lusiana, Retno A.; Rahayu, Maya D.

    2017-06-01

    Chromium metal(VI) is a valuable metal but in contrary has high toxicity, so the separation and recovery from waste are very important. One method that can be used for the separation and recovery of chromium (VI) is a Supported Liquid Membrane (SLM). SLM system contains of three main components: a supporting membrane, organic solvents and carrier compounds. The supported Membrane used in this research is Polytetrafluoroethylene (PTFE), organic solvent is kerosene, and the carrier compound used is aliquat 336. The supported liquid membrane is placed between two phases, namely, feed phase as the source of analyte (Cr(VI)) and the receiving phase as the result of separation. Feed phase is the electroplating waste which contains of chromium metal with pH variation about 4, 6 and 9. Whereas the receiving phase are the solution of HCl, NaOH, HCl-NaCl and NaOH-NaCl with pH variation about 1, 3, 5 and 7. The efficiency separation is determined by measurement of chromium in the feed and the receiving phase using AAS (Atomic Absorption Spectrophotometry). The experiment results show that transport of Chrom (VI) by Supported Liquid membrane (SLM) is influenced by pH solution in feed phase and receiving phase as well as NaCl in receiving phase. The highest chromium metal is transported from feed phase about 97,78%, whereas in receiving phase shows about 58,09%. The highest chromium metal transport happens on pH 6 in feed phase, pH 7 in receiving phase with the mixture of NaOH and NaCl using carrier compound aliquat 336.

  7. Dosimetric investigations of laser-induced phase transition of MX1-cell membranes by use of quantum dots

    Science.gov (United States)

    Beuthan, J.; Dressler, C.; Minet, O.; Müller, G.

    2006-05-01

    It is well known that laser scattered-light applicators when applied for laser-induced tumor therapy allow the precise thermal destruction of metastases. Using laser radiation in the NIR spectral range (usually, Nd:YAG laser systems λ = 1064 nm), a penetration depth of 5-10 cm (1/ e is the decrease in radiation intensity) is achieved in biological tissues. The major tissue-optical parameters, i.e., absorption coefficient μa, scattering coefficient μs, and the anisotropy factor g, show biological tissues to be strongly scattering media which have a so-called optical window in the NIR. As a consequence, the therapeutic laser radiation is scattered and absorbed at a deeper level, leading to a virtual enlargement of the laser applicator. The thermal sclerotization and the thermal cell damage originate within the absorbing volume of the laser radiation and spread outward by thermal diffusion. There are three dosimetrically relevant zones of thermal and biological damage: (1) a zone of thermal coagulation; (2) a threshold of partial necrosis (destruction of all metabolic processes in the cell is the maintenance of essential parts of the cytoskeleton and the plasma membrane); this is characterized by a specific temperature range, the so-called phase transition, which refers to the transition from the gel phase of the biomembrane to the fluid phase; the determination of this temperature zone is an integral part of the following experimental investigations on MX1 cells; (3) an external zone of thermal effects made up of partial and multiple damage with a statistical chance of survival. This paper describes the investigations on heat stress in cancer cells to verify the maximum phase transition of the outer MX1 cell membranes and the related results. For this purpose, a novel method of quantum dot fluorescence dosimetry was developed. The evaluation of the measured laser-induced fluorescences yields a first approximation of the determination of the phase transition on MX1

  8. Dense Plasma Focus Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Li, Shengtai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jungman, Gerard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hayes-Sterbenz, Anna Catherine [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-31

    The mechanisms for pinch formation in Dense Plasma Focus (DPF) devices, with the generation of high-energy ions beams and subsequent neutron production over a relatively short distance, are not fully understood. Here we report on high-fidelity 2D and 3D numerical magnetohydrodynamic (MHD) simulations using the LA-COMPASS code to study the pinch formation dynamics and its associated instabilities and neutron production.

  9. Phase separation in three-component lipid membranes: from Monte Carlo simulations to Ginzburg-Landau equations.

    Science.gov (United States)

    Reigada, Ramon; Buceta, Javier; Gómez, Jordi; Sagués, Francesc; Lindenberg, Katja

    2008-01-14

    Preferential affinity of cholesterol for saturated rather than unsaturated lipids underlies the thermodynamic process of the formation of lipid nanostructures in cell membranes, that is, of rafts. In this context, phase segregation of two-dimensional ternary lipid mixtures is formally studied from two different perspectives. The simplest approach is based on Monte Carlo simulations of an Ising model corresponding to two interconnected lattices, from which the basic features of the phenomenon are investigated. Then, the coarse-graining mean field procedure of the discrete Hamiltonian is adapted and a Ginzburg-Landau-like free energy expression is obtained. From this latter description, we construct kinetic equations that enable us to perform numerical simulations and to establish analytical phase separation criteria. Application of our formalism in the biological context is also discussed.

  10. Numerical simulation of three-dimensional gas/liquid two-phase flow in a proton exchange membrane fuel cell

    Institute of Scientific and Technical Information of China (English)

    ZHUGE Weilin; ZHANG Yangjun; MING Pingwen; LAO Xingsheng; CHEN Xiao

    2007-01-01

    Investigation into the formation and transport of liquid water in proton exchange membrane fuel cells (PEMFCs) is the key to fuel cell water management.A threedimensional gas/liquid two-phase flow and heat transfer model is developed based on the multiphase mixture theory.The reactant gas flow,diffusion,and chemical reaction as well as the liquid water transport and phase change process are modeled.Numerical simulations on liquid water distribution and its effects on the performance of a PEMFC are conducted.Results show that liquid water distributes mostly in the cathode,and predicted cell performance decreases quickly at high current density due to the obstruction of liquid water to oxygen diffusion.The simulation results agree well with experimental data.

  11. A novel microseeding method for the crystallization of membrane proteins in lipidic cubic phase.

    Science.gov (United States)

    Kolek, Stefan Andrew; Bräuning, Bastian; Stewart, Patrick Douglas Shaw

    2016-04-01

    Random microseed matrix screening (rMMS), in which seed crystals are added to random crystallization screens, is an important breakthrough in soluble protein crystallization that increases the number of crystallization hits that are available for optimization. This greatly increases the number of soluble protein structures generated every year by typical structural biology laboratories. Inspired by this success, rMMS has been adapted to the crystallization of membrane proteins, making LCP seed stock by scaling up LCP crystallization conditions without changing the physical and chemical parameters that are critical for crystallization. Seed crystals are grown directly in LCP and, as with conventional rMMS, a seeding experiment is combined with an additive experiment. The new method was used with the bacterial integral membrane protein OmpF, and it was found that it increased the number of crystallization hits by almost an order of magnitude: without microseeding one new hit was found, whereas with LCP-rMMS eight new hits were found. It is anticipated that this new method will lead to better diffracting crystals of membrane proteins. A method of generating seed gradients, which allows the LCP seed stock to be diluted and the number of crystals in each LCP bolus to be reduced, if required for optimization, is also demonstrated.

  12. Endobrevin/VAMP-8-dependent dense granule release mediates thrombus formation in vivo.

    Science.gov (United States)

    Graham, Gwenda J; Ren, Qiansheng; Dilks, James R; Blair, Price; Whiteheart, Sidney W; Flaumenhaft, Robert

    2009-07-30

    Individuals whose platelets lack dense or alpha-granules suffer various degrees of abnormal bleeding, implying that granule cargo contributes to hemostasis. Despite these clinical observations, little is known regarding the effects of impaired platelet granule secretion on thrombus formation in vivo. In platelets, SNARE proteins mediate the membrane fusion events required for granule cargo release. Endobrevin/VAMP-8 is the primary vesicle-SNARE (v-SNARE) responsible for efficient release of dense and alpha-granule contents; thus, VAMP-8(-/-) mice are a useful model to evaluate the importance of platelet granule secretion in thrombus formation. Thrombus formation, after laser-induced vascular injury, in these mice is delayed and decreased, but not absent. In contrast, thrombus formation is almost completely abolished in the mouse model of Hermansky-Pudlak syndrome, ruby-eye, which lacks dense granules. Evaluation of aggregation of VAMP-8(-/-) and ruby-eye platelets indicates that defective ADP release is the primary abnormality leading to impaired aggregation. These results demonstrate the importance of dense granule release even in the earliest phases of thrombus formation and validate the distal platelet secretory machinery as a potential target for antiplatelet therapies.

  13. Endobrevin/VAMP-8–dependent dense granule release mediates thrombus formation in vivo

    Science.gov (United States)

    Graham, Gwenda J.; Ren, Qiansheng; Dilks, James R.; Blair, Price; Flaumenhaft, Robert

    2009-01-01

    Individuals whose platelets lack dense or α-granules suffer various degrees of abnormal bleeding, implying that granule cargo contributes to hemostasis. Despite these clinical observations, little is known regarding the effects of impaired platelet granule secretion on thrombus formation in vivo. In platelets, SNARE proteins mediate the membrane fusion events required for granule cargo release. Endobrevin/VAMP-8 is the primary vesicle-SNARE (v-SNARE) responsible for efficient release of dense and α-granule contents; thus, VAMP-8−/− mice are a useful model to evaluate the importance of platelet granule secretion in thrombus formation. Thrombus formation, after laser-induced vascular injury, in these mice is delayed and decreased, but not absent. In contrast, thrombus formation is almost completely abolished in the mouse model of Hermansky-Pudlak syndrome, ruby-eye, which lacks dense granules. Evaluation of aggregation of VAMP-8−/− and ruby-eye platelets indicates that defective ADP release is the primary abnormality leading to impaired aggregation. These results demonstrate the importance of dense granule release even in the earliest phases of thrombus formation and validate the distal platelet secretory machinery as a potential target for antiplatelet therapies. PMID:19395672

  14. Rapid, highly efficient extraction and purification of membrane proteins using a microfluidic continuous-flow based aqueous two-phase system.

    Science.gov (United States)

    Hu, Rui; Feng, Xiaojun; Chen, Pu; Fu, Meng; Chen, Hong; Guo, Lin; Liu, Bi-Feng

    2011-01-07

    Membrane proteins play essential roles in regulating various fundamental cellular functions. To investigate membrane proteins, extraction and purification are usually prerequisite steps. Here, we demonstrated a microfluidic aqueous PEG/detergent two-phase system for the purification of membrane proteins from crude cell extract, which replaced the conventional discontinuous agitation method with continuous extraction in laminar flows, resulting in significantly increased extraction speed and efficiency. To evaluate this system, different separation and detection methods were used to identify the purified proteins, such as capillary electrophoresis, SDS-PAGE and nano-HPLC-MS/MS. Swiss-Prot database with Mascot search engine was used to search for membrane proteins from random selected bands of SDS-PAGE. Results indicated that efficient purification of membrane proteins can be achieved within 5-7s and approximately 90% of the purified proteins were membrane proteins (the highest extraction efficiency reported up to date), including membrane-associated proteins and integral membrane proteins with multiple transmembrane domains. Compared to conventional approaches, this new method had advantages of greater specific surface area, minimal emulsification, reduced sample consumption and analysis time. We expect the developed method to be potentially useful in membrane protein purifications, facilitating the investigation of membrane proteomics.

  15. Streamlined Membrane Proteome Preparation for Shotgun Proteomics Analysis with Triton X-100 Cloud Point Extraction and Nanodiamond Solid Phase Extraction

    Directory of Open Access Journals (Sweden)

    Minh D. Pham

    2016-05-01

    Full Text Available While mass spectrometry (MS plays a key role in proteomics research, characterization of membrane proteins (MP by MS has been a challenging task because of the presence of a host of interfering chemicals in the hydrophobic protein extraction process, and the low protease digestion efficiency. We report a sample preparation protocol, two-phase separation with Triton X-100, induced by NaCl, with coomassie blue added for visualizing the detergent-rich phase, which streamlines MP preparation for SDS-PAGE analysis of intact MP and shot-gun proteomic analyses. MP solubilized in the detergent-rich milieu were then sequentially extracted and fractionated by surface-oxidized nanodiamond (ND at three pHs. The high MP affinity of ND enabled extensive washes for removal of salts, detergents, lipids, and other impurities to ensure uncompromised ensuing purposes, notably enhanced proteolytic digestion and down-stream mass spectrometric (MS analyses. Starting with a typical membranous cellular lysate fraction harvested with centrifugation/ultracentrifugation, MP purities of 70%, based on number (not weight of proteins identified by MS, was achieved; the weight-based purity can be expected to be much higher.

  16. Viscoelastic behavior of dense microemulsions

    Science.gov (United States)

    Cametti, C.; Codastefano, P.; D'arrigo, G.; Tartaglia, P.; Rouch, J.; Chen, S. H.

    1990-09-01

    We have performed extensive measurements of shear viscosity, ultrasonic absorption, and sound velocity in a ternary system consisting of water-decane-sodium di(2-ethylhexyl)sulfo- succinate(AOT), in the one-phase region where it forms a water-in-oil microemulsion. We observe a rapid increase of the static shear viscosity in the dense microemulsion region. Correspondingly the sound absorption shows unambiguous evidence of a viscoelastic behavior. The absorption data for various volume fractions and temperatures can be reduced to a universal curve by scaling both the absorption and the frequency by the measured static shear viscosity. The sound absorption can be interpreted as coming from the high-frequency tail of the viscoelastic relaxation, describable by a Cole-Cole relaxation formula with unusually small elastic moduli.

  17. Monitoring of N-methyl carbamate pesticide residues in water using hollow fibre supported liquid membrane and solid phase extraction

    Science.gov (United States)

    Msagati, Titus A. M.; Mamba, Bhekie B.

    The aim of this work was to develop a method for the determination of N-methyl carbamates in water involving hollow fibre supported liquid membrane (HFSLM) and solid phase extraction (SPE) as sample preparation methods. Four N-methyl carbamate pesticides, aldicarb, carbaryl, carbofuran and methiocarb sulfoxide, were simultaneously extracted and analysed by a liquid chromatograph with a diode array detector (LC-UV/DAD) and a liquid chromatograph coupled to a ion trap quadrupole mass spectrometer (LC-ESI-MS). The high performance liquid chromatography (HPLC) separation of carabamate extracts was performed on a C18 column with water-acetonitrile as the mobile phase. The mass spectrometry analyses were carried out in the positive mode, operating under both the selected ion monitoring (SIM) and full scan modes. The solid phase recoveries of the extracts ranged between 8% and 98%, with aldicarb having the highest recoveries, followed by carbaryl, carbofuran and methiocarb had the lowest recovery. The HFSLM recovery ranged between 8% and 58% and the order of recovery was similar to the SPE trend. Factors controlling the efficiency of the HFSLM extraction such as sample pH, stripping phase pH, enrichment time, stirring speed as well as organic solvent used for entrapment of analytes, were optimised to achieve the highest enrichment factors.

  18. Low pH induces an interdigitated gel to bilayer gel phase transition in dihexadecylphosphatidylcholine membrane.

    Science.gov (United States)

    Furuike, S; Levadny, V G; Li, S J; Yamazaki, M

    1999-10-01

    We have investigated the influence of pH on the structures and phase behaviors of multilamellar vesicles of the ether-linked dihexadecylphosphatidylcholine (DHPC-MLV). This phospholipid is known to be in the interdigitated gel (L(beta)I) phase in excess water at 20 degrees C at neutral pH. The results of X-ray diffraction experiments indicate that a phase transition from L(beta)I phase to the bilayer gel phase occurred in DHPC-MLV in 0.5 M KCl around pH 3.9 with a decrease in pH, and that at low pH values, less than pH 2.2, DHPC-MLVs were in L(beta') phase. The results of fluorescence and light scattering method indicate that the gel to liquid-crystalline phase transition temperature (T(m)) of DHPC-MLV increased with a decrease in pH. On the basis of a thermodynamic analysis, we conclude that the main mechanism of the low-pH induced L(beta)I to bilayer gel phase transition in DHPC-MLV and the increase in its T(m) is connected with the decrease in the repulsive interaction between the headgroups of these phospholipids. As pH decreases, the phosphate groups of the headgroups begin to be protonated, and as a result, the apparent positive surface charges appear. However, surface dipoles decrease and the interaction free energy of the hydrophilic segments with water increases. The latter effect dominates the pure electrostatic repulsion between the charged headgroups, and thereby, the total repulsive interaction in the interface decreases.

  19. New Polymeric Membranes for Organic Solvent Nanofiltration

    KAUST Repository

    Aburabie, Jamaliah

    2017-05-01

    The focus of this dissertation was the development, synthesis and modification of polymers for the preparation of membranes for organic solvent nanofiltration. High chemical stability in a wide range of solvents was a key requirement. Membranes prepared from synthesized polymers as well as from commercial polymers were designed and chemically modified to reach OSN requirements. A solvent stable thin-film composite (TFC) membrane is reported, which is fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate. The membranes exhibited high fluxes towards solvents like THF, DMF and DMSO ranging around 20 L/m2 h at 5 bar with a MWCO of around 1000 g/mol. Ultrafiltration PTSC membranes were prepared by non-solvent induced phase separation and crosslinked with GPTMS. The crosslinking reaction was responsible for the formation of an inorganic-type-network that tuned the membrane pore size. The crosslinked membranes acquired high solvent stability in DMSO, DMF and THF with a MWCO above 1300 g/mol. Reaction Induced Phase Separation (RIPS) was introduced as a new method for the preparation of skinned asymmetric membranes. These membranes have two distinctive layers with different morphologies both from the same polymer. The top dense layer is composed of chemically crosslinked polymer chains while the bottom layer is a porous structure formed by non-crosslinked polymer chains. Such membranes were tested for vitamin B12 in solvents after either crosslinking the support or dissolving the support and fixing the freestanding membrane on alumina. Pebax® 1657 was utilized for the preparation of composite membranes by simple coating. Porous PAN membranes were coated with Pebax® 1657 which was then crosslinked using TDI. Crosslinked Pebax® membranes show high stability towards ethanol, propanol and acetone. The membranes were also stable in DMF once crosslinked PAN supports were used. Sodium alginate polymer was investigated for the preparation of thin film composite

  20. Structure and phase transitions of the multilamellar DMPC membranes in presence of the DMSO and DESO

    Science.gov (United States)

    Gorshkova, Yu E.; Ivankov, O. I.

    2017-05-01

    The structure and phase transitions of the prepared and formed spontaneously multilamellar vesicles (MLVs) of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in dimethyl sulfoxide (DMSO) and diethyl sulfoxide (DESO) were investigated using small angle neutron scattering (SANS). The both polar aprotic solvents increase the temperature of the main phase transition (Tm ). The pre-transition does not observed at sulfoxides mole fraction X = 0.2. The transition of the MLVs DMPC in the presence DMSO from gel to liquid-crystalline phase occurs at lower temperature. The method of the MLVs preparation has directly effects on the temperature of the main phase transition and its structure. The value of Tm is higher with ∼ 4.6 ºC in case of the spontaneous forming MLVs from extruded ULVs. The thickness of the solvent layer for prepared MLVs is less by 4.0 Å in gel phase and by 5.6 Å in liquid-crystalline phase than the thickness of the solvent layer for spontaneously formed MLVs.

  1. Microstructural Phase Changes of DPPC-Ergosterol Supported Membranes Stressed by Ethanol

    Science.gov (United States)

    Vanegas, Juan; Block, David; Faller, Roland; Longo, Marjorie

    2010-03-01

    Microstructure of DPPC-Ergosterol supported lipid bilayers (SLBs) stressed by ethanol is examined at the nanoscopic level using atomic force microscopy (AFM). Alcohols such as ethanol are known to cause changes in the phase behavior of phospholipids as well as inducing the formation of an interdigitated phase of reduced thickness, where the hydrophobic tails of the top and bottom lipids intercalate causing an increase in the area per lipid as well as the solvent exposed surface of the headgroups. SLBs composed of 75-100 mole % 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine (DPPC) and 0-25 mole % ergosterol were deposited on mica through the vesicle deposition method. In order to observe the ethanol-induced phase changes that can be observed in free bilayers, the vesicles must be prepared in buffer solution containing ethanol. The presence of salt is required to reduce the effect of the strong interaction between the bilayers and the support, which in the absence of ethanol and salt induces the formation of a tilted phase similar to the interdigitated phase in DPPC bilayers deposited above the melting temperature. As previously observer by other groups, ethanol-induced changes in SLBs often require heating above the transition temperature after addition of ethanol, or sample preparation in the presence of the alcohol. The later method was used as it produces more consistent results and the observations agree well with the previously reported phase diagram of DPPC-Ergosterol with ethanol.

  2. Dense deposit disease in a child with febrile sore throat

    Directory of Open Access Journals (Sweden)

    Giovanni Conti

    2017-01-01

    Full Text Available Dense deposit disease or membranoproliferative glomerulonephritis type II is a rare glomerulopathy characterized on renal biopsy by deposition of abnormal electron-dense material in the glomerular basement membrane. The pathophysiologic basis is uncontrolled systemic activation of the alternate pathway of the complement cascade. C3 nephritic factor, an autoantibody directed against the C3 convertase of the alternate pathway, plays a key role. In some patients, complement gene mutations have been identified. We report the case of a child who had persistent microscopic hematuria, proteinuria, and hypocomplementemia C3 for over 2 months. Renal biopsy confirmed the diagnosis of dense deposit disease.

  3. Removal of volatile to semi-volatile organic contaminants from water using hollow fiber membrane contactors and catalytic destruction of the contaminants in the gas phase

    OpenAIRE

    Tarafder, Shamsul Abedin

    2007-01-01

    Abstract Chlorinated organic compounds and ether compounds are frequently found in groundwater and efficient treatment options are needed. In this study, the efficient transferal of the compounds from the water phase to the gas phase was studied followed by the catalytic treatment of the gas phase. For the removal of the organic contaminants from water, a microporous polypropylene hollow fiber membrane (HFM) module was operated under low strip gas flow to water flow ratios (_< 5:1). Rem...

  4. Lattice simulations of phase morphology on lipid bilayers: Renormalization, membrane shape, and electrostatic dipole interactions

    Science.gov (United States)

    Amazon, Jonathan J.; Feigenson, Gerald W.

    2015-01-01

    When liquid phases coexist at equilibrium but are not driven to minimize domain interfacial contact energy, the resulting patterns of phase domains can have important implications for living cells. In this study we explore some of the interactions and conditions that produce the stable patterned phases that are observed in model lipid mixtures. By use of Monte Carlo simulations we find that background curvature is important for the formation of patterned (modulated) phases. The interactions that stabilize nanoscopic phase separation are still not well understood. We show that inclusion of an electrostatic dipole repulsion with decay lengths as short as two to four lipid diameters can break up domains at the nanometer scale and that the location of the miscibility critical point is sensitive to this interaction. The use of a coarse-grained simulation raises questions about comparing parameters in simulations performed at different length scales. Using renormalization group techniques we show how to reconcile this problem, treating line tension as a running coupling constant. PMID:25353504

  5. 高密度二氧化碳技术的杀菌机制及其在食品工业中的应用%Sterilization Mechanisms and Application of Dense-phase Carbon Dioxide in Food Processing

    Institute of Scientific and Technical Information of China (English)

    顾丰颖; 卢嘉; 王晓拓; 王爱华; 李敏敏; 贺妍; 范蓓

    2013-01-01

    Nowadays, dense phase CO2(DPCD) technology gradually emerges in the food industry as a new non-thermal pasteurization technology. This paper summarized the bactericidal mechanism of DPCD, the influencing factors for pasteurization, and its application in food industry, which provides reference for in-depth study and potential application.%近年来,作为一种新型的非热杀菌技术,高密度二氧化碳技术( DPCD)逐渐在食品工业中崭露头角。对该技术的杀菌机理进行系统的阐述,对影响杀菌效果的因素进行分析,并且对目前高密度二氧化碳技术在食品工业领域的应用进行综述,以期为高密度二氧化碳技术的深入研究与应用提供参考。

  6. DENSE PHASE REBURN COMBUSTION SYSTEM (DPRCS) DEMONSTRATION ON A 154 MWE TANGENTIAL FURNACE: ADDITIONAL AREA OF INTEREST-TO DEVELOP AND DEMONSTRATE AN IN-FURNACE MULTI-POLLUTANT REDUCTION TECHNOLOGY TO REDUCE NOx, SO2 & Hg

    Energy Technology Data Exchange (ETDEWEB)

    Allen C. Wiley; Steven Castagnero; Geoff Green; Kevin Davis; David White

    2004-03-01

    Semi-dense phase pneumatic delivery and injection of calcium and sodium sorbents, and microfine powdered coal, at various sidewall elevations of an online operating coal-fired power plant, was investigated for the express purpose of developing an in-furnace, economic multi-pollutant reduction methodology for NO{sub x}, SO{sub 2} & Hg. The 154 MWe tangentially-fired furnace that was selected for a full-scale demonstration, was recently retrofitted for NO{sub x} reduction with a high velocity rotating-opposed over-fire air system. The ROFA system, a Mobotec USA technology, has a proven track record of breaking up laminar flow along furnace walls, thereby enhancing the mix of all constituents of combustion. The knowledge gained from injecting sorbents and micronized coal into well mixed combustion gases with significant improvement in particulate retention time, should serve well the goals of an in-furnace multi-pollutant reduction technology; that of reducing back-end cleanup costs on a wide variety of pollutants, on a cost per ton basis, by first accomplishing significant in-furnace reductions of all pollutants.

  7. Platelet adhesion, contact phase coagulation activation, and C5a generation of polyethylene glycol acid-grafted high flux cellulosic membrane with varieties of grafting amounts.

    Science.gov (United States)

    Fushimi, F; Nakayama, M; Nishimura, K; Hiyoshi, T

    1998-10-01

    Grafting of polyethylene glycol chains onto cellulosic membrane can be expected to reduce the interaction between blood (plasma protein and cells) and the membrane surface. Alkylether carboxylic acid (PEG acid) grafted high flux cellulosic membranes for hemodialysis, in which the polyethylene glycol chain bears an alkyl group at one side and a carboxyl group at the other side, have been developed and evaluated. PEG acid-grafted high flux cellulosic membranes with various grafting amounts have been compared with respect to platelet adhesion, the contact phase of blood coagulation, and complement activation in vitro. A new method of quantitating platelet adhesion on hollow-fiber membrane surfaces has been developed, which is based on the determination of lactate dehydrogenase (LDH) activity after lysis of the adhered platelets. PEG acid-grafted high flux cellulosic membranes showed reduced platelet adhesion and complement activation effects in grafting amounts of 200 ppm or higher without detecting adverse effects up to grafting amounts of 850 ppm. The platelet adhesion of a PEG acid-grafted cellulosic membrane depends on both the flux and grafting amounts of the membrane. It is concluded that the grafting of PEG acid onto a cellulosic membrane improves its biocompatibility as evaluated in terms of platelet adhesion, complement activation, and thrombogenicity.

  8. Numerical Simulation on Dune Flow in Pressurized Dense Phase Pneumatic Conveying of Pulverized Coal in Horizontal Pipe%水平管加压密相煤粉气力输送沙丘流的数值模拟

    Institute of Scientific and Technical Information of China (English)

    蒲文灏; 赵长遂

    2011-01-01

    对Johnson等提出的摩擦正应力模型和Syamlal等提出的摩擦剪切黏度模型进行了修正,并将其与颗粒动理学理论相结合,建立了可以描述加压密相气力输送的气固湍流流动状况的三维多相流模型.该模型充分考虑了颗粒间碰撞和摩擦力作用,以及气相和颗粒团湍流脉动之间的相互作用.采用该模型对加压密相气力输送水平管沙丘流流动特性进行了三维数值模拟,并预测了单个沙丘和连续沙丘的形成及运动状况.结果表明:随着表观气速的增加,煤粉颗粒浓度减小,压降梯度呈现先减小后增大的趋势;在横截面上,煤粉颗粒分布呈现上窄下宽的趋势,且煤粉颗粒在管道底部沉积,并呈现月牙形状.模拟结果与试验结果吻合较好.%Modifications were made for the frictional normal stresses model proposed by Johnson et al. and the frictional shear viscosity model proposed by Syamlal et al. Combining the modified model with the kinetic theory for granular flow, a 3-D multi-phase flow model was built up for gas-solid turbulent flow in pressurized dense phase pneumatic conveying. The model sufficiently took account of the collision and friction action among particles, and the interaction among gas phase and turbulent fluctuation of particles.The model was used to carry out the 3-D numerical simulation for the dune flow characteristics in pressurized dense phase pneumatic conveying in a horizontal pipe. The formation and motion process of the single dune and the continuous dunes were predicted. Results show that with the increase of apparent gas velocity, the concentration of pulverized coal decreases, and the pressure drop gradient decreases at first and then increases. On the cross section, the distribution of pulverized coal appears to be narrow on the upper part and broad on the lower part. Besides, there are coal particles deposited on the bottom of the pipe to form the dune. The simulated results agree well

  9. Coarse-grained molecular dynamics simulation of binary charged lipid membranes: Phase separation and morphological dynamics

    CERN Document Server

    Ito, Hiroaki; Shimokawa, Naofumi

    2016-01-01

    Biomembranes, which are mainly composed of neutral and charged lipids, exhibit a large variety of functional structures and dynamics. Here, we report a coarse-grained molecular dynamics (MD) simulation of the phase separation and morphological dynamics in charged lipid bilayer vesicles. The screened long-range electrostatic repulsion among charged head groups delays or inhibits the lateral phase separation in charged vesicles compared with neutral vesicles, suggesting the transition of the phase-separation mechanism from spinodal decomposition to nucleation or homogeneous dispersion. Moreover, the electrostatic repulsion causes morphological changes, such as pore formation, and further transformations into disk, string, and bicelle structures, which are spatiotemporally coupled to the lateral segregation of charged lipids. Based on our coarse-grained MD simulation, we propose a plausible mechanism of pore formation at the molecular level. The pore formation in a charged-lipid-rich domain is initiated by the p...

  10. Small interfering ribonucleic acid induces liquid-to-ripple phase transformation in a phospholipid membrane

    Science.gov (United States)

    Choubey, Amit; Nomura, Ken-ichi; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

    2014-09-01

    Small interfering ribonucleic acid (siRNA) molecules play a pivotal role in silencing gene expression via the RNA interference mechanism. A key limitation to the widespread implementation of siRNA therapeutics is the difficulty of delivering siRNA-based drugs to cells. Here, we examine changes in the structure and dynamics of a dipalmitoylphosphatidylcholine bilayer in the presence of a siRNA molecule and mechanical barriers to siRNA transfection in the bilayer. Our all-atom molecular dynamics simulation shows that siRNA induces a liquid crystalline-to-ripple phase transformation in the bilayer. The ripple phase consists of a major region of non-interdigitated and a minor region of interdigitated lipid molecules with an intervening kink. In the ripple phase, hydrocarbon chains of lipid molecules have large compressive stresses, which present a considerable barrier to siRNA transfection.

  11. Effects of pentanol isomers on the phase behavior of phospholipid bilayer membranes.

    Science.gov (United States)

    Griffin, Kathryn L; Cheng, Chih-Yin; Smith, Eric A; Dea, Phoebe K

    2010-11-01

    Differential scanning calorimetry (DSC) was used to analyze the thermotropic phase behavior of dipalmitoylphosphatidylcholine (DPPC) bilayers in the presence of pentanol isomers. The concentration of each pentanol isomer needed to induce the interdigitated phase was determined by the appearance of a biphasic effect in the main transition temperatures, the onset of a hysteresis associated with the main transition from the gel-to-liquid crystalline phase, and the disappearance of the pretransition. Lower threshold concentrations were found to correlate with isomers of greater alkyl chain length while branching of the alkyl chain was found to increase biphasic behavior. The addition of a methyl group to butanol systems drastically decreased threshold concentrations. However, as demonstrated in the DPPC/neopentanol system, branching of the alkyl chain away from the -OH group lowers the threshold concentration while maintaining a biphasic effect.

  12. Small interfering ribonucleic acid induces liquid-to-ripple phase transformation in a phospholipid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Choubey, Amit; Nomura, Ken-ichi; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

    2014-09-15

    Small interfering ribonucleic acid (siRNA) molecules play a pivotal role in silencing gene expression via the RNA interference mechanism. A key limitation to the widespread implementation of siRNA therapeutics is the difficulty of delivering siRNA-based drugs to cells. Here, we examine changes in the structure and dynamics of a dipalmitoylphosphatidylcholine bilayer in the presence of a siRNA molecule and mechanical barriers to siRNA transfection in the bilayer. Our all-atom molecular dynamics simulation shows that siRNA induces a liquid crystalline-to-ripple phase transformation in the bilayer. The ripple phase consists of a major region of non-interdigitated and a minor region of interdigitated lipid molecules with an intervening kink. In the ripple phase, hydrocarbon chains of lipid molecules have large compressive stresses, which present a considerable barrier to siRNA transfection.

  13. Liquid-liquid electro-organo-synthetic processes in a carbon nanofibre membrane microreactor: Triple phase boundary effects in the absence of intentionally added electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, John D.; Ahn, Sunyhik D.; Taylor, James E.; Bull, Steven D. [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Bulman-Page, Philip C. [School of Chemistry, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Marken, Frank, E-mail: F.Marken@bath.ac.uk [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)

    2011-07-30

    Graphical abstract: Display Omitted Highlights: > Amphiphilic carbon nanofiber membrane employed in electro-synthesis. > Triple phase boundary process within a carbon membrane. > Electrochemical deuteration in a liquid|liquid micro-reactor system. > Triple phase boundary reaction zone effects in electro-synthesis. - Abstract: An amphiphilic carbon nanofibre membrane electrode (ca. 50 nm fibre diameter, 50-100 {mu}m membrane thickness) is employed as an active working electrode and separator between an aqueous electrolyte phase (with reference and counter electrode) and an immiscible organic acetonitrile phase (containing only the redox active material). Potential control is achieved with a reference and counter electrode located in the aqueous electrolyte phase, but the electrolysis is conducted in the organic acetonitrile phase in the absence of intentionally added supporting electrolyte. For the one-electron oxidation of n-butylferrocene coupled to perchlorate anion transfer from aqueous to organic phase effective electrolysis is demonstrated with an apparent mass transfer coefficient of m = 4 x 10{sup -5} m s{sup -1} and electrolysis of typically 1 mg n-butylferrocene in a 100 {mu}L volume. For the two-electron reduction of tetraethyl-ethylenetetracarboxylate the apparent mass transfer coefficient m = 4 x 10{sup -6} m s{sup -1} is lower due to a less extended triple phase boundary reaction zone in the carbon nanofibre membrane. Nevertheless, effective electrolysis of up to 6 mg tetraethyl-ethylenetetracarboxylate in a 100 {mu}L volume is demonstrated. Deuterated products are formed in the presence of D{sub 2}O electrolyte media. The triple phase boundary dominated mechanism and future microreactor design improvements are discussed.

  14. Purification of inkjet ink from water using liquid phase, electric discharge polymerization and cellulosic membrane filtration.

    Science.gov (United States)

    Jordan, Alexander T; Hsieh, Jeffery S; Lee, Daniel T

    2013-01-01

    A method to separate inkjet ink from water was developed using a liquid phase, electric discharge process. The liquid phase, electric discharge process with filtration or sedimentation was shown to remove 97% of inkjet ink from solutions containing between 0.1-0.8 g/L and was consistent over a range of treatment conditions. Additionally, particle size analysis of treated allyl alcohol and treated propanol confirmed the electric discharge treatment has a polymerization mechanism, and small molecule analysis of treated methanol using gas chromatography and mass spectroscopy confirmed the mechanism was free radical initiated polymerization.

  15. Dense Suspension Splash

    Science.gov (United States)

    Zhang, Wendy; Dodge, Kevin M.; Peters, Ivo R.; Ellowitz, Jake; Klein Schaarsberg, Martin H.; Jaeger, Heinrich M.

    2014-03-01

    Upon impact onto a solid surface at several meters-per-second, a dense suspension plug splashes by ejecting liquid-coated particles. We study the mechanism for splash formation using experiments and a numerical model. In the model, the dense suspension is idealized as a collection of cohesionless, rigid grains with finite surface roughness. The grains also experience lubrication drag as they approach, collide inelastically and rebound away from each other. Simulations using this model reproduce the measured momentum distribution of ejected particles. They also provide direct evidence supporting the conclusion from earlier experiments that inelastic collisions, rather than viscous drag, dominate when the suspension contains macroscopic particles immersed in a low-viscosity solvent such as water. Finally, the simulations reveal two distinct routes for splash formation: a particle can be ejected by a single high momentum-change collision. More surprisingly, a succession of small momentum-change collisions can accumulate to eject a particle outwards. Supported by NSF through its MRSEC program (DMR-0820054) and fluid dynamics program (CBET-1336489).

  16. Dense Axion Stars

    CERN Document Server

    Braaten, Eric; Zhang, Hong

    2015-01-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure.If the axion mass energy is $mc^2= 10^{-4}$ eV, these dilute axion stars have a maximum mass of about $10^{-14} M_\\odot$. We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If $mc^2 = 10^{-4}$ eV, the first branch of these dense axion stars has mas...

  17. Dense Axion Stars

    Science.gov (United States)

    Braaten, Eric; Mohapatra, Abhishek; Zhang, Hong

    2016-09-01

    If the dark matter particles are axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound systems of axions. In the previously known solutions for axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. The mass of these dilute axion stars cannot exceed a critical mass, which is about 10-14M⊙ if the axion mass is 10-4 eV . We study axion stars using a simple approximation to the effective potential of the nonrelativistic effective field theory for axions. We find a new branch of dense axion stars in which gravity is balanced by the mean-field pressure of the axion Bose-Einstein condensate. The mass on this branch ranges from about 10-20M⊙ to about M⊙ . If a dilute axion star with the critical mass accretes additional axions and collapses, it could produce a bosenova, leaving a dense axion star as the remnant.

  18. Dense Axion Stars

    Science.gov (United States)

    Mohapatra, Abhishek; Braaten, Eric; Zhang, Hong

    2016-03-01

    If the dark matter consists of axions, gravity can cause them to coalesce into axion stars, which are stable gravitationally bound Bose-Einstein condensates of axions. In the previously known axion stars, gravity and the attractive force between pairs of axions are balanced by the kinetic pressure. If the axion mass energy is mc2 =10-4 eV, these dilute axion stars have a maximum mass of about 10-14M⊙ . We point out that there are also dense axion stars in which gravity is balanced by the mean-field pressure of the axion condensate. We study axion stars using the leading term in a systematically improvable approximation to the effective potential of the nonrelativistic effective field theory for axions. Using the Thomas-Fermi approximation in which the kinetic pressure is neglected, we find a sequence of new branches of axion stars in which gravity is balanced by the mean-field interaction energy of the axion condensate. If mc2 =10-4 4 eV, the first branch of these dense axion stars has mass ranging from about 10-11M⊙ toabout M⊙.

  19. DENSE MEDIUM CYCLONE OPTIMIZATON

    Energy Technology Data Exchange (ETDEWEB)

    Gerald H. Luttrell; Chris J. Barbee; Peter J. Bethell; Chris J. Wood

    2005-06-30

    Dense medium cyclones (DMCs) are known to be efficient, high-tonnage devices suitable for upgrading particles in the 50 to 0.5 mm size range. This versatile separator, which uses centrifugal forces to enhance the separation of fine particles that cannot be upgraded in static dense medium separators, can be found in most modern coal plants and in a variety of mineral plants treating iron ore, dolomite, diamonds, potash and lead-zinc ores. Due to the high tonnage, a small increase in DMC efficiency can have a large impact on plant profitability. Unfortunately, the knowledge base required to properly design and operate DMCs has been seriously eroded during the past several decades. In an attempt to correct this problem, a set of engineering tools have been developed to allow producers to improve the efficiency of their DMC circuits. These tools include (1) low-cost density tracers that can be used by plant operators to rapidly assess DMC performance, (2) mathematical process models that can be used to predict the influence of changes in operating and design variables on DMC performance, and (3) an expert advisor system that provides plant operators with a user-friendly interface for evaluating, optimizing and trouble-shooting DMC circuits. The field data required to develop these tools was collected by conducting detailed sampling and evaluation programs at several industrial plant sites. These data were used to demonstrate the technical, economic and environmental benefits that can be realized through the application of these engineering tools.

  20. Symmetry energy in cold dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Kie Sang, E-mail: k.s.jeong@yonsei.ac.kr; Lee, Su Houng, E-mail: suhoung@yonsei.ac.kr

    2016-01-15

    We calculate the symmetry energy in cold dense matter both in the normal quark phase and in the 2-color superconductor (2SC) phase. For the normal phase, the thermodynamic potential is calculated by using hard dense loop (HDL) resummation to leading order, where the dominant contribution comes from the longitudinal gluon rest mass. The effect of gluonic interaction on the symmetry energy, obtained from the thermodynamic potential, was found to be small. In the 2SC phase, the non-perturbative BCS paring gives enhanced symmetry energy as the gapped states are forced to be in the common Fermi sea reducing the number of available quarks that can contribute to the asymmetry. We used high density effective field theory to estimate the contribution of gluon interaction to the symmetry energy. Among the gluon rest masses in 2SC phase, only the Meissner mass has iso-spin dependence although the magnitude is much smaller than the Debye mass. As the iso-spin dependence of gluon rest masses is even smaller than the case in the normal phase, we expect that the contribution of gluonic interaction to the symmetry energy in the 2SC phase will be minimal. The different value of symmetry energy in each phase will lead to different prediction for the particle yields in heavy ion collision experiment.

  1. Predictions of Phase Separation in Three-Component Lipid Membranes by the MARTINI Force Field

    DEFF Research Database (Denmark)

    Davis, Ryan S.; Sunil Kumar, P. B.; Sperotto, Maria Maddalena;

    2013-01-01

    PCs, such as dilinoleyl-phosphatidylcholine (DUPC) and diarachidonoyl-phosphatidylcholine (DAPC). Through systematic tweaking of the interactions between the hydrophobic groups of the PC molecules, we show that the appearance of phase separation in three-component lipid bilayers, as modeled through...

  2. Nonbilayer phase of lipoplex-membrane mixture determines endosomal escape of genetic cargo and transfection efficiency

    NARCIS (Netherlands)

    Zuhorn, IS; Bakowsky, U; Polushkin, E; Visser, WH; Stuart, MCA; Engberts, JBFN; Hoekstra, D; Visser, Willy H.

    2005-01-01

    Cationic lipids are widely used for gene delivery, and inclusion of dioleoylphosphatidylethanolamine (DOPE) as a helper lipid in cationic lipid-DNA formulations often promotes transfection efficacy. To investigate the significance of DOPE's preference to adopt a hexagonal phase in the mechanism of t

  3. Non-isothermal two-phase transport in the polymer electrolyte membrane fuel cell microporous layer

    Science.gov (United States)

    Ge, Nan

    This thesis investigates the water transport mechanisms in the crack-free microporous layer (MPL) of a polymer electrolyte membrane (PEM) fuel cell. Synchrotron X-ray radiography was used to visualize and quantify the in situ liquid water in the gas diffusion layers (GDLs) of an operating fuel cell. A methodology was developed to correct the artefact of imaging sample movement. Furthermore, to address inaccuracies due to the scattering effect and higher harmonics at the synchrotron beamline, a calibration technique was introduced in order to experimentally determine the liquid water X-ray attenuation coefficient. Through in situ radiography, liquid water breakthrough events were observed in the MPL, and measured water thicknesses were used as inputs into a one-dimensional (1D) heat and mass transport model. The 1D model was used to describe the coupled relationship between liquid and vapour transport through the cathode MPL and the temperature distributions in the operating fuel cell.

  4. Study of the two-phase dummy load shut-down strategy for proton exchange membrane fuel cells

    Science.gov (United States)

    Zhang, Q.; Lin, R.; Cui, X.; Xia, S. X.; Yang, Z.; Chang, Y. T.

    2017-02-01

    This paper presents a new system strategy designed to alleviate the performance decay caused by start-up/shut-down (SU/SD) conditions in proton exchange membrane fuel cells (PEMFCs). The innovative method was tested using a two-phase dummy load composed of a linearly declined main load and a fixed small auxiliary load. The initial value of the main load must be controlled within a proper range, and a closed-ended air exhaust is necessary. According to the analysis of in-situ current density distribution during SD processes, the two-phase dummy load can continuously fit the process of oxygen reduction in the cathode, whereas the conventional dummy load leads to local air starvation. Polarization curves and cyclic voltammetry (CV) were employed to evaluate the performance decay during SU/SD repetition. After tests of 900 cycles, the highest voltage degradation rate of the PEMFC was 3.33 μV cycle-1 (800 mA cm-2), and the electrochemical surface area (ECSA) loss was 0.0046 m2 g-1 cycle-1 with the two-phase dummy load strategy. After comparing results with similar work on a single PEMFC, the authors confirmed the preeminent effectiveness of this strategy. This strategy will also improve fuel cell stack performance due to controllable SD duration and comparatively low performance decay rates.

  5. Research on vacuum membrane distillation technique disposing of high concentration inorganic salt reverse osmosis dense dewatering%减压膜蒸馏技术处理无机高盐 RO 浓排水研究

    Institute of Scientific and Technical Information of China (English)

    郭建中; 路全忠; 杨才伟

    2012-01-01

      针对无机高盐 RO 浓排水具有含盐量高难处理的特点,本文研究了减压膜蒸馏技术处理无机高盐RO 浓排水试验阶段中不同料液温度、真空度、流速对膜通量的影响.结果表明:料液温度、真空度、流速与膜通量存在相关性.随着料液温度和真空度的提高,膜通量会相应增加;随着料液流速的增加膜通量也有增加,但流速小于0.2 m/s 时对膜通量的影响明显,当流速大于0.2m/s 时对膜通量影响小%  Aimed at the characteristic of high salinity and difficult dispose of high concentration inorganic salt reverse osmosis dewatering, this paper studies the vacuum membrane distillation technique dispose of high concentration inorganic salt reverse osmosis dewatering, and analyse the influence of different vacuum, material fluid temperature, flow velocity to membrane flux. The result shows that there is a correlation between membrane flux and vacuum, material fluid temperature and flow velocity. With increasing of vacuum and material fluid temperature, membrane flux increased accordingly; and when the velocity increased and membrane flux increased at the same time. With the velocity was less than 0.2 m/s, the influence to membrane flux came to be obvious, when the velocity was above 0.2 m/s, the influence to membrane flux went light.

  6. Electrospun doping of carbon nanotubes and platinum nanoparticles into the β-phase polyvinylidene difluoride nanofibrous membrane for biosensor and catalysis applications.

    Science.gov (United States)

    Zhang, Panpan; Zhao, Xinne; Zhang, Xuan; Lai, Yue; Wang, Xinting; Li, Jingfeng; Wei, Gang; Su, Zhiqiang

    2014-05-28

    A novel β-phase polyvinylidene difluoride (PVDF) nanofibrous membrane decorated with multiwalled carbon nanotubes (MWCNTs) and platinum nanoparticles (PtNPs) was fabricated by an improved electrospinning technique. The morphology of the fabricated PVDF-MWCNT-PtNP nanofibrous membrane was observed by scanning electron microscopy, and the formation of high β-phase in the hybrid nanofibrous membrane was investigated by Fourier transform infrared spectroscopy and differential scanning calorimetry. The uniform dispersion of MWCNTs and PtNPs in the PVDF hybrid nanofibrous membrane and their interaction were explored by transmission electron microscopy and X-ray diffraction. For the first time, we utilized this created PVDF-MWCNT-PtNP nanofibrous membrane for biosensor and catalysis applications. The nonenzymatic amperometric biosensor with highly stable and sensitive, and selective detection of both H2O2 and glucose was successfully fabricated based on the electrospun PVDF-MWCNT-PtNP nanofibrous membrane. In addition, the catalysis of the hybrid nanofibrous membrane for oxygen reduction reaction was tested, and a good catalysis performance was found. We anticipate that the strategies utilized in this work will not only guide the further design of functional nanofiber-based biomaterials and biodevices but also extend the potential applications in energy storage, cytology, and tissue engineering.

  7. Phase diagrams and morphological evolution in wrapping of rod-shaped elastic nanoparticles by cell membrane: a two-dimensional study.

    Science.gov (United States)

    Yi, Xin; Gao, Huajian

    2014-06-01

    A fundamental understanding of cell-nanomaterial interaction is essential for biomedical diagnostics, therapeutics, and nanotoxicity. Here, we perform a theoretical analysis to investigate the phase diagram and morphological evolution of an elastic rod-shaped nanoparticle wrapped by a lipid membrane in two dimensions. We show that there exist five possible wrapping phases based on the stability of full wrapping, partial wrapping, and no wrapping states. The wrapping phases depend on the shape and size of the particle, adhesion energy, membrane tension, and bending rigidity ratio between the particle and membrane. While symmetric morphologies are observed in the early and late stages of wrapping, in between a soft rod-shaped nanoparticle undergoes a dramatic symmetry breaking morphological change while stiff and rigid nanoparticles experience a sharp reorientation. These results are of interest to the study of a range of phenomena including viral budding, exocytosis, as well as endocytosis or phagocytosis of elastic particles into cells.

  8. [Ultrastructure of glomerular podocyts in the incipient phase of minimal change nephrotic syndrome with thin basement membrane disease].

    Science.gov (United States)

    Ogawa, Ryo; Miyoshi, Ken-ichi; Nagao, Tomoaki; Jotoku, Masanori; Irita, Jun; Okura, Takafumi; Higaki, Jitsuo

    2012-01-01

    An 80-year-old woman was referred to the Division of Nephrology at Ehime University Hospital because of leg edema in December 2010. She had been treated with 300 mg of tocopherol for scleroderma since 2007 and treated with 9 mg of prednisolone (PSL) for autoimmune hearing loss since 2010. Due to the occurrence of mild hematuria (5-9/HPF), proteinuria (0.9 g/day) and an increased serum creatinine level (1.31 mg/dL), a renal biopsy was performed. Light microscopy (LM) showed minor abnormality in the glomeruli, and immunohistology showed the absence of deposits of immunoglobulins and complements. Electron microscopy (EM) showed a thin glomerular basement membrane with a limited level of podocyte abnormalities. Due to the findings of intimal thickening of interlobular arteries and subcapsular accumulation of global sclerosis on LM, she was diagnosed with nephrosclerosis and thin basement membrane disease. Four weeks later, her leg edema had increased considerably and urinary protein had increased to 12.4 g/day. The second biopsy showed similar findings in LM and IF as the first biopsy, but EM revealed diffuse foot process effacement. She was diagnosed with minimal change nephrotic syndrome (MCNS) and treated with methylprednisolone pulse therapy followed by 40 mg of oral PSL. Her urinary protein had completely disappeared 6 weeks later. Complete remission with PSL treatment indicates that urinary protein at first renal biopsy was due to MCNS. Our case exhibited podocyte features in the incipient phase of human MCNS.

  9. Chemiluminescence-imaging detection of DNA on a solid-phase membrane by using a peroxidase-labeled macromolecular probe.

    Science.gov (United States)

    Azam, Md Golam; Yamasuji, Mutsumi; Krawczyk, Tomasz; Shibata, Takayuki; Kabashima, Tsutomu; Kai, Masaaki

    2015-07-01

    We have developed a novel method for sensitive chemiluminescence (CL)-imaging detection of DNA by using a macromolecular probe synthesized by attaching multiple molecules of horseradish peroxidase (HRP) and biotin in dextran backbone. The probe formed a macromolecular assembly by binding to streptavidin which specifically recognized biotinylated complementary DNA, which was hybridized to a target DNA on a solid-phase membrane. This methodology was applied to CL-imaging detection of a synthetic telomere DNA (TTAGGG)10 and human telomere DNA by using the CL probe comprising of dextranT2000 (MW=ca. 2000kDa) bonded to approximately 42 molecules of HRP and 210 molecules of biotin. The human telomere DNA in a small number of buccal mucous cells (ca. 70 cell numbers) of cheek tissue was quantitatively determined by the proposed CL detection method that afforded approximately 10 times higher sensitivity than that of the conventional CL method using commercially available HRP-avidin probe.

  10. Multidimensional representations of the phase response curve for both type 1 and type 2 membrane excitability

    Science.gov (United States)

    Raidt, Robert; Smith, Andrew J.; Oprisan, Sorinel A.

    2012-02-01

    Neurons are complex excitable cells with a highly nonlinear response to external perturbations, such as presynaptic inputs and biological noise. Single-cell activity is determined by the properties of ionic channels and the ionic makeup of cell's environment and is mathematically described by coupled and nonlinear evolution equations. The phase resetting curve (PRC) reduces the complexity of the biophysical mechanisms involved in generating action potentials to tabulating advances or delays of subsequent spikes of a neuron due to an external perturbation. The PRC is widely used to predict the activity of large neural networks that by replacing the computationally intensive integration of evolution equations with lookup tables. The fundamental assumption of the PRC approach in predicting phase-locked modes in coupled neural networks is that the transient PRC measured for isolated and bursting neurons (open-loop) remains the same under the recurrent inputs of a phase-locked mode (close-loop). The novelties of our approach are: 1) the use of discrete sine transforms (DST's) to store the PRC's as a series of coefficients, and 2) the use of multidimensional stacks to represent multidimensional objects.

  11. A new infrared spectroscopoic marker for cochleate phases in phosphatidylserine-containing model membranes.

    Science.gov (United States)

    Flach, C R; Mendelsohn, R

    1993-01-01

    Fourier transform-infrared (IR) spectroscopic and electron microscopic studies are reported for 1,2-dimyristoylphosphatidylserine (DMPS) and for DMPS/1,2-dimyristoylphosphatidylcholine mixtures in the presence and absence of Ca2+ ion. The frequency of the methyl symmetric deformation mode near 1,378 cm-1, previously assumed insensitive to changes in lipid morphology, has been found to respond to cochleate phase formation by undergoing an approximately 8 cm-1 increase. The new IR spectroscopic marker at 1,386 cm-1 has been used to identify and verify structures suggested from the phase diagram of J. R. Silvius and J. Gagné (1984. Biochemistry. 23:3241-3247) for this system. In addition, the ability of Mg2+ ion to induce cochleate formation has been demonstrated. Higher Mg2+ than Ca2+ levels are required for this process. Finally, IR spectroscopy has been used to monitor dehydration of the lipid surface through changes in the asymmetric PO2- stretching mode. Dehydration precedes cochleate phase formation (i.e., occurs at a lower Ca2+/phosphatidylserine level). Images FIGURE 3 FIGURE 3 PMID:8494975

  12. Joining of Ion Transport Membranes Using a Novel Transient Liquid Phase Process

    Energy Technology Data Exchange (ETDEWEB)

    Darryl P. Butt

    2006-08-30

    The feasibility of a novel transient liquid phase (TLP) joining method has been demonstrated in joining La{sub 0.9}Ca{sub 0.1}FeO{sub 3} materials. Metal oxide powders were processed to form the TLP compositions which were used in the joining process. The method has been successful in producing joint interfaces that effectively disappear, as they are the same material and have the same properties as the joined parts. The feasibility of the method has been demonstrated for a single system, but many systems where the method can potentially be applied have been identified.

  13. Characteristics of PVdF-HFP/TiO{sub 2} composite membrane electrolytes prepared by phase inversion and conventional casting methods

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwang Man; Ryu, Kwang Sun; Chang, Soon Ho [Ionics Devices Team, Basic Research Lab., Electronics and Telecommunications Research Institute (ETRI), 161 Gajong, Yusong, Daejon 305-700 (Korea, Republic of); Park, Nam-Gyu [Materials Science and Technology Division, Korea Institute of Science and Technology (KIST), 39-1 Hwaolgok, Seongbuk, Seoul 136-791 (Korea, Republic of)

    2006-08-15

    Porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based polymer membranes filled with various contents of titania (TiO{sub 2}) nanocrystalline particles are prepared by phase inversion technique and, along with conventional casting method for comparison. N-methyl-2-pyrrolidone (NMP) as a solvent is used to dissolve the polymer and to make the slurry with TiO{sub 2}. Cast film is obtained by spreading the slurry and evaporating NMP in a dry oven, while phase inversion membrane by promptly immersing the spread slurry into flowing water as a non-solvent. Physical and electrochemical characterizations, such as morphology, thermal and crystalline behavior, and other transport properties of lithium ionic species, are carried out for the polymer films/membranes and the polymer electrolytes with absorbing an electrolyte solution. Phase inversion polymer electrolytes are proved to show superior behaviors in electrochemical properties, such as ionic conductivity, electrochemical and interfacial stability, than cast film electrolytes. This is greatly owed to highly porous structure of phase inversion membranes. Even including the feature of interfacial resistance with lithium electrode, phase inversion polymer electrolytes of PVdF-HFP/(5-20wt.% TiO{sub 2}) can be optimized as the adequate ones in applying to the electrolyte medium of lithium rechargeable batteries. (author)

  14. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui

    2010-09-01

    The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.

  15. Numerical modeling for dilute and dense sprays

    Science.gov (United States)

    Chen, C. P.; Kim, Y. M.; Shang, H. M.; Ziebarth, J. P.; Wang, T. S.

    1992-01-01

    We have successfully implemented a numerical model for spray-combustion calculations. In this model, the governing gas-phase equations in Eulerian coordinate are solved by a time-marching multiple pressure correction procedure based on the operator-splitting technique. The droplet-phase equations in Lagrangian coordinate are solved by a stochastic discrete particle technique. In order to simplify the calculation procedure for the circulating droplets, the effective conductivity model is utilized. The k-epsilon models are utilized to characterize the time and length scales of the gas phase in conjunction with turbulent modulation by droplets and droplet dispersion by turbulence. This method entails random sampling of instantaneous gas flow properties and the stochastic process requires a large number of computational parcels to produce the satisfactory dispersion distributions even for rather dilute sprays. Two major improvements in spray combustion modelings were made. Firstly, we have developed a probability density function approach in multidimensional space to represent a specific computational particle. Secondly, we incorporate the Taylor Analogy Breakup (TAB) model for handling the dense spray effects. This breakup model is based on the reasonable assumption that atomization and drop breakup are indistinguishable processes within a dense spray near the nozzle exit. Accordingly, atomization is prescribed by injecting drops which have a characteristic size equal to the nozzle exit diameter. Example problems include the nearly homogeneous and inhomogeneous turbulent particle dispersion, and the non-evaporating, evaporating, and burning dense sprays. Comparison with experimental data will be discussed in detail.

  16. Separation membrane development

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.W. [Savannah River Technology Center, Aiken, SC (United States)

    1998-08-01

    A ceramic membrane has been developed to separate hydrogen from other gases. The method used is a sol-gel process. A thin layer of dense ceramic material is coated on a coarse ceramic filter substrate. The pore size distribution in the thin layer is controlled by a densification of the coating materials by heat treatment. The membrane has been tested by permeation measurement of the hydrogen and other gases. Selectivity of the membrane has been achieved to separate hydrogen from carbon monoxide. The permeation rate of hydrogen through the ceramic membrane was about 20 times larger than Pd-Ag membrane.

  17. 高密度CO_2预处理对樱桃番茄干燥的影响%Effect of dense phase carbon dioxide pretreatment on drying cherry tomato

    Institute of Scientific and Technical Information of China (English)

    龙婉蓉; 郭蕴涵; 赵翠萍; 汪政富; 胡小松

    2012-01-01

    将樱桃番茄经过和未经过高密度CO2(DPCD)预处理,然后进行热风干燥,以比较干燥速率和干燥后产品品质的变化,探索新型干燥工艺。结果发现,经过1、2和3MPaDPCD处理组与对照组相比,干燥速率提高,干燥时间缩短,产品收缩率降低,复水率提高,褐变度没有显著变化;但经高压处理的干燥产品VC和颜色比对照组差。综合各指标分析,除了VC和颜色,DPCD预处理后的干燥指标优于对照组。%In order to explore a new drying technique,cherry tomatoes treated with and without dense phase carbon dioxide(DPCD) were dried with hot air,and their drying rates and physicochemical quality were compared.The results indicated that,as compared to the control group without pretreatment of DPCD,the cherry tomatoes after DPCD treatment at 1,2,and 3MPa reduced in drying time and shrinkage,and increased in drying rate and rehydration rate,while their browning degrees had no significant change.The VC content and color of the dried products after higher DPCD pretreatment were significantly worse than that of the control group,In a word,excepted color and VC,the drying effect of cherry tomatoes after DPCD pretreatment was better than that of the control group.

  18. 高密度二氧化碳对荔枝汁品质的影响%Effect of Dense Phase Carbon Dioxide on the Quality of Litchi Juice

    Institute of Scientific and Technical Information of China (English)

    徐玉娟; 温靖; 肖更生; 吴继军; 陈于陇; 余元善; 唐道邦; 潘思轶

    2012-01-01

    In order to investigate the effect of dense phase carbon dioxide(DPCD) as a non-thermal sterilization technology on the quality and physio-chemical properties of litchi juice,freshly prepared litchi juice was subjected to DPCD treatment at 8 MPa and 36 ℃ for 10 min.The changes of pH,soluble solid content,conductivity,browning degree,vitamin C and free amino acids were evaluated.The results showed that DPCD treatment had a significant effect on pH,total acidity and PPO,but had no obvious effect on other indicators.Slight increases in reducing sugar,total polyphenol content and free amino acid content in DPCD-treated litchi juice were observed.%为探讨高密度二氧化碳(DPCD)非热杀菌技术对荔枝汁品质的影响,将新鲜荔枝汁经DPCD处理(8MPa、3 6℃、1 0 m in)后,测定p H值、可溶性固形物含量、电导率、褐变度、V C含量和游离氨基酸含量等指标的变化。结果表明:DPCD处理对荔枝汁的pH值、总酸度和多酚氧化酶(PPO)活性有显著影响,经DPCD处理后荔枝汁的还原糖、总多酚和游离氨基酸的含量略有增加,其他指标没有明显变化。

  19. 高密度二氧化碳对脂肪氧化酶活性与结构变性的影响%The Efiects of Dense Phase Carbon Dioxide on the Activity and Denaturation of Lipoxygenase

    Institute of Scientific and Technical Information of China (English)

    贝君; 吴继红; 廖小军; 胡小松

    2008-01-01

    研究了高密度二氧化碳(Dense Phase Carbon Dioxide,DPCD)技术对脂肪氧化酶(Lipoxygenase,LOX)活性与结构变性的影响.采用分光光度法测定LOX的活性,通过测定处理后的巯基含量、浊度等指标考察蛋白质的变性程度;采用电泳方法及透射电镜(Transmission Electric Microscopy,TEM)对处理过的LOX蛋白分子进行形态观察.试验结果显示,DPCD处理对LOX的钝化效果显著高于温和热处理的.55℃处理30min,酶活接近20%.而DPCD(55℃、10MPa)处理30min,酶活不到5%.随着处理温度和压强的增加,LOX活性显著下降,在温度55℃、压强大于10MPa时,LOX已经完全失活.DPCD处理后,LOX液中游离-SH基团的含量和浊度值显著增加,表明DPCD处理使LOX发生了变性.活性电泳和透射电镜观察结果表明,在55℃进行DPCD处理,可能导致LOX蛋白分子的聚合.

  20. Numerical Simulation of Vertical Upward Dense Phase Suspension Pneumatic Conveying Based on EMMS Model%基于EMMS模型垂直向上密相悬浮气力输送过程数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    潘刚

    2015-01-01

    基于EMMS模型,建立垂直向上密相悬浮输送过程的数学模型。对输送管道内固体颗粒的速度、体积分数以及管道内压力变化进行了研究。研究结果表明:固体颗粒在管道发生团聚现象;在高度方向上,固体颗粒速度呈现出先减小后趋于稳定的变化趋势,固相颗粒平均体积分数呈现出先增加后平稳的趋势;在高度=3.5~8 m范围内气力输送过程趋于稳定。%The mathematical model of vertical upward dense phase suspended transportation process is established based on EMMS model. The velocity and volume fraction of solid particles in the conveying pipeline and the pressure changes in the pipeline are studied. Research results show that agglomeration of solid particles in the pipeline.The velocity of solid particles decreases firstly and then tends to be stable in height direction.The average volume fraction of the solid particles increased first and then tends to be stable in height direction.The pneumatic conveying process is stable in the height h=3.5~8 m range.

  1. Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas, Phase 1. [Poly(etherimide) and poly(ether-ester-amide) membranes

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    During the last quarter several high performance membranes for the separation of hydrogen from nitrogen, carbon monoxide, hydrogen sulfide and carbon dioxide. The heat-resistant resin poly(etherimide) has been selected as the polymer with the most outstanding properties for the separation of hydrogen from nitrogen and carbon monoxide. Flat sheet and hollow fiber poly(etherimide) membranes have been prepared and evaluated with pure gases and gas mixtures at elevated pressures and temperatures. Multilayer composite poly(ether-ester-amide) membranes were also developed. These membranes are useful for the separation of carbon dioxide and hydrogen sulfide hydrogen. They have very high selectivities and extremely high normalized carbon dioxide and hydrogen sulfide fluxes. Separation of carbon dioxide/hydrogen streams is a key problem in hydrogen production from coal. The development of the two membranes now gives us two approaches to separate these gas streams, depending on the stream's composition. If the stream contains small quantities of hydrogen, the hydrogen- permeable poly(etherimide) membrane would be used to produce a hydrogen-enriched permeate. If the stream contains small quantities of carbon dioxide or hydrogen sulfide, the poly(ether-ester-amide) membrane would be used to produce a carbon dioxide/hydrogen sulfide-free, hydrogen-enriched residue stream. 6 fig., 4 tabs.

  2. Supported liquid membrane-protected molecularly imprinted beads for micro-solid phase extraction of sulfonamides in environmental waters.

    Science.gov (United States)

    Díaz-Álvarez, M; Barahona, F; Turiel, E; Martín-Esteban, A

    2014-08-29

    In this work, molecularly imprinted polymer (MIP) beads have been prepared and evaluated for the development of a supported liquid membrane-protected micro-solid phase extraction method for the analysis of sulfonamides (SAs) in aqueous samples. The performance of MIP beads was firstly evaluated in cartridges by conventional solid-phase extraction for the simultaneous analysis of SAs. Afterward, beads were packed into a polypropylene hollow fiber protected by an organic solvent immobilized in the pores of the capillary wall. During the process, the analytes were extracted from the aqueous sample to the immobilized organic solvent and then selectively retained by the MIP beads located inside the capillary. The effect of various experimental parameters as sample pH, time and stirring-rate among others, were studied for the establishment of optimum rebinding conditions. Relative recoveries for all sulfonamides tested in river and reservoir water samples by the proposed method using 100mL water sample spiked with 50μg L-1 of each sulfonamide were within 70-120%, with a relative standard deviation (RSD) <10% (n=3). The detection limits (LODs) were within 0.2-3μgL(-1), depending upon the sulfonamide and the type of water used.

  3. Alternate phase variation in expression of two major surface membrane proteins (MBA and UU376) of Ureaplasma parvum serovar 3.

    Science.gov (United States)

    Zimmerman, Carl-Ulrich R; Stiedl, Thomas; Rosengarten, Renate; Spergser, Joachim

    2009-03-01

    Ureaplasma urealyticum and Ureaplasma parvum are commensals and pathogens of the human urogenital tract and of newborn infants. There are four distinct U. parvum serovars and 10 distinct U. urealyticum serovars. Both species possess a distinct immunodominant variable surface protein, the multiple banded antigen (MBA), which shows size variability among isolates as a result of changes in the number of C-terminal repeating units. Adjacent to the MBA gene (UU375) lies UU376, which was annotated as 'Ureaplasma-specific conserved hypothetical gene'. In four different strains of U. parvum serovar 3, we demonstrated expression of UU376 by Western blot analysis and phase variation between UU376, here designated Upvmp376 (Ureaplasma phase-variable membrane protein 376), and MBA after application of selective pressure with hyperimmune antisera directed against either protein. By Southern blot analysis, we found that the switch between MBA and Upvmp376 expression is associated with a DNA inversion event in which the nonrepetitive region of the MBA gene and its putative promoter region are opposed to either the repetitive region of MBA or UU376. We propose that in U. parvum serovar 3, and presumably in all U. parvum and U. urealyticum, an inversion event at specific sites effects an alternate ON/OFF switching of the genes UU375 and UU376.

  4. From charge-mosaic to micelle self-assembly: Block copolymer membranes in the last 40 years

    KAUST Repository

    Nunes, Suzana Pereira

    2013-01-23

    Different strategies for membrane preparation based on block copolymers are reviewed in this paper, starting from early papers on charge-mosaic membranes and following with dense membranes for gas separation for applications like CO2 separation, pervaporation of aqueous solutions containing organic pollutants, low-fouling surfaces and finally tailoring porous membranes with very sharp pore size distribution. The approaches for manufacture of nanoporous films are summarized, including etching and preferential dissolution. The advantages of a new process based on micelle assembly and phase inversion are emphasized, confirming its perspective of up-scale and application at large scale. © 2012 American Chemical Society.

  5. Development of novel CO{sub 2}-stable oxygen permeable dual phase membranes for CO{sub 2} capture in an oxy-fuel process

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Huixia

    2012-07-19

    The combustion of fossil fuels in power stations with pure oxygen following the oxy-fuel process allows the Sequestration of CO{sub 2}. The pure oxygen needed can be separated from air by oxygen transporting ceramics like single phase perovskites. However, most of the so far developed single phase perovskites have stability problems in a CO{sub 2} containing atmosphere. Dual phase membranes are micro-scale mixtures of an electron conducting phase and an oxygen ion conducting phase and their compositions can be tailored according to practical requirements, which are considered to be promising substitutes for the single phase perovskite materials. In my thesis the issues of phase stability for perovskite-type material with the common composition Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 3-{delta}} (BSCF) as weil as the development of a series of novel CO{sub 2}-stable dual phase membranes were studied. In Chapter 2, the phase stability and permeation behavior of a dead-end BSCF tube membrane in high-purity oxygen at temperatures below 750 C, were elucidated using powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), high-angle annular dark-field (HAADF) and scanning transmission electron microscopy (STEM). lt was found that parts of the cubic perovskite BSCF transformed into a hexagonal perovskite Ba{sub 0.5{+-}x}Sr{sub 0.5{+-}x}CoO{sub 3-{delta}} (x {approx} 0.1) and a trigonal mixed oxide Ba{sub 1-x}Sr{sub x}CO{sub 2-y}Fe{sub y}O{sub 5{+-}{delta}} (x {approx} 0.15, y {approx} 0.25) in high-purity oxygen at 750 C. On the other hand, it was found that the partial degradation of cubic BSCF perovskite at 750 C was more pronounced under the strongly oxidizing conditions on the oxygen supply (feed) side than on the oxygen release (permeate) side of the membrane. The structural instability of BSCF is attributed to an oxidation of cobalt from Co{sup 2+} to Co{sup 3+} and Co{sup 4+}, which exhibits an ionic radius that is too small to be tolerated by

  6. Dense matter at RAON: Challenges and possibilities

    Science.gov (United States)

    Lee, Yujeong; Lee, Chang-Hwan; Gaitanos, T.; Kim, Youngman

    2016-11-01

    Dense nuclear matter is ubiquitous in modern nuclear physics because it is related to many interesting microscopic and macroscopic phenomena such as heavy ion collisions, nuclear structure, and neutron stars. The on-going rare isotope science project in Korea will build up a rare isotope accelerator complex called RAON. One of the main goals of RAON is to investigate rare isotope physics including dense nuclear matter. Using the relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) transport code, we estimate the properties of nuclear matter that can be created from low-energy heavyion collisions at RAON.We give predictions for the maximum baryon density, the isospin asymmetry and the temperature of nuclear matter that would be formed during 197Au+197Au and 132Sn+64Ni reactions. With a large isospin asymmetry, various theoretical studies indicate that the critical densities or temperatures of phase transitions to exotic states decrease. Because a large isospin asymmetry is expected in the dense matter created at RAON, we discuss possibilities of observing exotic states of dense nuclear matter at RAON for large isospin asymmetry.

  7. A comprehensive review of the lipid cubic phase or in meso method for crystallizing membrane and soluble proteins and complexes

    Energy Technology Data Exchange (ETDEWEB)

    Caffrey, Martin, E-mail: martin.caffrey@tcd.ie [Trinity College Dublin, Dublin (Ireland)

    2015-01-01

    A comprehensive and up-to-date review of the lipid cubic phase or in meso method for crystallizing membrane and soluble proteins and complexes is reported. Recent applications of the method for in situ serial crystallography at X-ray free-electron lasers and synchrotrons are described. The lipid cubic phase or in meso method is a robust approach for crystallizing membrane proteins for structure determination. The uptake of the method is such that it is experiencing what can only be described as explosive growth. This timely, comprehensive and up-to-date review introduces the reader to the practice of in meso crystallogenesis, to the associated challenges and to their solutions. A model of how crystallization comes about mechanistically is presented for a more rational approach to crystallization. The possible involvement of the lamellar and inverted hexagonal phases in crystallogenesis and the application of the method to water-soluble, monotopic and lipid-anchored proteins are addressed. How to set up trials manually and automatically with a robot is introduced with reference to open-access online videos that provide a practical guide to all aspects of the method. These range from protein reconstitution to crystal harvesting from the hosting mesophase, which is noted for its viscosity and stickiness. The sponge phase, as an alternative medium in which to perform crystallization, is described. The compatibility of the method with additive lipids, detergents, precipitant-screen components and materials carried along with the protein such as denaturants and reducing agents is considered. The powerful host and additive lipid-screening strategies are described along with how samples that have low protein concentration and cell-free expressed protein can be used. Assaying the protein reconstituted in the bilayer of the cubic phase for function is an important element of quality control and is detailed. Host lipid design for crystallization at low temperatures and for

  8. Dense Hypervelocity Plasma Jets

    Science.gov (United States)

    Case, Andrew; Witherspoon, F. Douglas; Messer, Sarah; Bomgardner, Richard; Phillips, Michael; van Doren, David; Elton, Raymond; Uzun-Kaymak, Ilker

    2007-11-01

    We are developing high velocity dense plasma jets for fusion and HEDP applications. Traditional coaxial plasma accelerators suffer from the blow-by instability which limits the mass accelerated to high velocity. In the current design blow-by is delayed by a combination of electrode shaping and use of a tailored plasma armature created by injection of a high density plasma at a few eV generated by arrays of capillary discharges or sparkgaps. Experimental data will be presented for a complete 32 injector gun system built for driving rotation in the Maryland MCX experiment, including data on penetration of the plasma jet through a magnetic field. We present spectroscopic measurements of plasma velocity, temperature, and density, as well as total momentum measured using a ballistic pendulum. Measurements are in agreement with each other and with time of flight data from photodiodes and a multichannel PMT. Plasma density is above 10^15 cm-3, velocities range up to about 100 km/s. Preliminary results from a quadrature heterodyne HeNe interferometer are consistent with these results.

  9. Solid-phase extraction and purification of membrane proteins using a UV-modified PMMA microfluidic bioaffinity μSPE device.

    Science.gov (United States)

    Battle, Katrina N; Jackson, Joshua M; Witek, Małgorzata A; Hupert, Mateusz L; Hunsucker, Sally A; Armistead, Paul M; Soper, Steven A

    2014-03-21

    We present a novel microfluidic solid-phase extraction (μSPE) device for the affinity enrichment of biotinylated membrane proteins from whole cell lysates. The device offers features that address challenges currently associated with the extraction and purification of membrane proteins from whole cell lysates, including the ability to release the enriched membrane protein fraction from the extraction surface so that they are available for downstream processing. The extraction bed was fabricated in PMMA using hot embossing and was comprised of 3600 micropillars. Activation of the PMMA micropillars by UV/O3 treatment permitted generation of surface-confined carboxylic acid groups and the covalent attachment of NeutrAvidin onto the μSPE device surfaces, which was used to affinity select biotinylated MCF-7 membrane proteins directly from whole cell lysates. The inclusion of a disulfide linker within the biotin moiety permitted release of the isolated membrane proteins via DTT incubation. Very low levels (∼20 fmol) of membrane proteins could be isolated and recovered with ∼89% efficiency with a bed capacity of 1.7 pmol. Western blotting indicated no traces of cytosolic proteins in the membrane protein fraction as compared to significant contamination using a commercial detergent-based method. We highlight future avenues for enhanced extraction efficiency and increased dynamic range of the μSPE device using computational simulations of different micropillar geometries to guide future device designs.

  10. Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation

    NARCIS (Netherlands)

    Wibisono, Yusuf; Yandi, Wetra; Golabi, Mohsen; Nugraha, Roni; Cornelissen, Emile R.; Kemperman, Antoine J.B.; Ederth, Thomas; Nijmeijer, Kitty

    2015-01-01

    Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG10MA

  11. Effects of octane on the fatty acid composition and transition temperature of Pseudomonas oleovorans membrane lipids during growth in two-liquid-phase continuous cultures

    NARCIS (Netherlands)

    Chen, Qi; Nijenhuis, Atze; Preusting, Hans; Dolfing, Jan; Janssen, Dick B.; Witholt, Bernard

    1995-01-01

    Growth of Pseudomonas oleovorans GPol in continuous culture containing a bulk n-octane phase resulted in changes of the fatty acid composition of the membrane lipids. Compared to citrate-grown cells, the ratio of C-18 to C-16 fatty acids and the ratio of unsaturated to saturated fatty acids increase

  12. Effects of octane on the fatty acid composition and transition temperature of Pseudomonas oleovorans membrane lipids during growth in two-liquid-phase continuous cultures

    NARCIS (Netherlands)

    Chen, Qi; Nijenhuis, Atze; Preusting, Hans; Dolfing, Jan; Janssen, Dick B.; Witholt, Bernard

    1995-01-01

    Growth of Pseudomonas oleovorans GPol in continuous culture containing a bulk n-octane phase resulted in changes of the fatty acid composition of the membrane lipids. Compared to citrate-grown cells, the ratio of C18 to C16 fatty acids and the ratio of unsaturated to saturated fatty acids increased

  13. Visualization of membrane protein crystals in lipid cubic phase using X-ray imaging.

    Science.gov (United States)

    Warren, Anna J; Armour, Wes; Axford, Danny; Basham, Mark; Connolley, Thomas; Hall, David R; Horrell, Sam; McAuley, Katherine E; Mykhaylyk, Vitaliy; Wagner, Armin; Evans, Gwyndaf

    2013-07-01

    The focus in macromolecular crystallography is moving towards even more challenging target proteins that often crystallize on much smaller scales and are frequently mounted in opaque or highly refractive materials. It is therefore essential that X-ray beamline technology develops in parallel to accommodate such difficult samples. In this paper, the use of X-ray microradiography and microtomography is reported as a tool for crystal visualization, location and characterization on the macromolecular crystallography beamlines at the Diamond Light Source. The technique is particularly useful for microcrystals and for crystals mounted in opaque materials such as lipid cubic phase. X-ray diffraction raster scanning can be used in combination with radiography to allow informed decision-making at the beamline prior to diffraction data collection. It is demonstrated that the X-ray dose required for a full tomography measurement is similar to that for a diffraction grid-scan, but for sample location and shape estimation alone just a few radiographic projections may be required.

  14. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; N. Nagabhushana; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. Thermogravimetric analysis (TGA) was carried out on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} to investigate oxygen deficiency ({delta}) of the sample. The TGA was performed in a controlled atmosphere using oxygen, argon, carbon monoxide and carbon dioxide with adjustable gas flow rates. In this experiment, the weight loss and gain of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} was directly measured by TGA. The weight change of the sample was evaluated at between 600 and 1250 C in air or 1000 C as a function of oxygen partial pressure. The oxygen deficiencies calculated from TGA data as a function of oxygen activity and temperature will be estimated and compared with that from neutron diffraction measurement in air. The LSFT and LSFT/CGO membranes were fabricated from the powder obtained from Praxair Specialty Ceramics. The sintered membranes were subjected to microstructure analysis and hardness analysis. The LSFT membrane is composed of fine grains with two kinds of grain morphology. The grain size distribution was characterized using image analysis. In LSFT/CGO membrane a lot of grain pullout was observed from the less dense, porous phase. The hardness of the LSFT and dual phase membranes were studied at various loads. The hardness values obtained from the cross section of the membranes were also compared to that of the values obtained from the surface. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. Measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} as a function of temperature an oxygen partial pressure are reported. Further analysis of the dilatometry data obtained previously is presented. A series of isotope transients

  15. Heavy mesons in dense matter

    NARCIS (Netherlands)

    Tolos, Laura; Gamermann, Daniel; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; LlanesEstrada, FJ; Pelaez,

    2011-01-01

    Charmed mesons in dense matter are studied within a unitary coupled-channel approach which takes into account Pauli-blocking effects and meson self-energies in a self-consistent manner. We obtain the open-charm meson spectral functions in this dense medium, and discuss their implications on hidden c

  16. The symmetry energy in cold dense matter

    CERN Document Server

    Jeong, Kie Sang

    2015-01-01

    We calculate the symmetry energy in cold dense matter both in the normal quark phase and in the 2-color superconductor (2SC) phase. For the normal phase, the thermodynamic potential is calculated by using hard dense loop (HDL) resummation to leading order, where the dominant contribution comes from the longitudinal gluon rest mass. The effect of gluonic interaction to the symmetry energy, obtained from the thermodynamic potential, was found to be small. In the 2SC phase, the non-perturbative BCS paring gives enhanced symmetry energy as the gapped states are forced to be in the common Fermi sea reducing the number of available quarks that can contribute to the asymmetry. We used high density effective field theory to estimate the contribution of gluon interaction to the symmetry energy. Among the gluon rest masses in 2SC phase, only the Meissner mass has iso-spin dependence although the magnitude is much smaller than the Debye mass. As the iso-spin dependence of gluon rest masses is even smaller than the case ...

  17. Development of novel CO{sub 2}-stable oxygen permeable dual phase membranes for CO{sub 2} capture in an oxy-fuel process

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Huixia

    2012-07-19

    The combustion of fossil fuels in power stations with pure oxygen following the oxy-fuel process allows the Sequestration of CO{sub 2}. The pure oxygen needed can be separated from air by oxygen transporting ceramics like single phase perovskites. However, most of the so far developed single phase perovskites have stability problems in a CO{sub 2} containing atmosphere. Dual phase membranes are micro-scale mixtures of an electron conducting phase and an oxygen ion conducting phase and their compositions can be tailored according to practical requirements, which are considered to be promising substitutes for the single phase perovskite materials. In my thesis the issues of phase stability for perovskite-type material with the common composition Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 3-{delta}} (BSCF) as weil as the development of a series of novel CO{sub 2}-stable dual phase membranes were studied. In Chapter 2, the phase stability and permeation behavior of a dead-end BSCF tube membrane in high-purity oxygen at temperatures below 750 C, were elucidated using powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), high-angle annular dark-field (HAADF) and scanning transmission electron microscopy (STEM). lt was found that parts of the cubic perovskite BSCF transformed into a hexagonal perovskite Ba{sub 0.5{+-}x}Sr{sub 0.5{+-}x}CoO{sub 3-{delta}} (x {approx} 0.1) and a trigonal mixed oxide Ba{sub 1-x}Sr{sub x}CO{sub 2-y}Fe{sub y}O{sub 5{+-}{delta}} (x {approx} 0.15, y {approx} 0.25) in high-purity oxygen at 750 C. On the other hand, it was found that the partial degradation of cubic BSCF perovskite at 750 C was more pronounced under the strongly oxidizing conditions on the oxygen supply (feed) side than on the oxygen release (permeate) side of the membrane. The structural instability of BSCF is attributed to an oxidation of cobalt from Co{sup 2+} to Co{sup 3+} and Co{sup 4+}, which exhibits an ionic radius that is too small to be tolerated by

  18. Chemistry in a spinneret - On the interplay of crosslinking and phase inversion during spinning of novel hollow fiber membranes

    NARCIS (Netherlands)

    Kopec, K.K.; Dutczak, S.M.; Wessling, Matthias; Stamatialis, Dimitrios

    2011-01-01

    This work explores a new method of simultaneous membrane formation and chemical modification in a spinning process for fabricating asymmetric composite hollow fiber membranes. This method is based on controlled crosslinking reaction between the membrane forming polyimide P84 and the chemically

  19. Exploiting the Phenomenon of Liquid-Liquid Phase Separation for Enhanced and Sustained Membrane Transport of a Poorly Water-Soluble Drug.

    Science.gov (United States)

    Indulkar, Anura S; Gao, Yi; Raina, Shweta A; Zhang, Geoff G Z; Taylor, Lynne S

    2016-06-01

    Recent studies on aqueous supersaturated lipophilic drug solutions prepared by methods including antisolvent addition, pH swing, or dissolution of amorphous solid dispersions (ASDs) have demonstrated that when crystallization is slow, these systems undergo liquid-liquid phase separation (LLPS) when the concentration of the drug in the medium exceeds its amorphous solubility. Following LLPS, a metastable equilibrium is formed where the concentration of drug in the continuous phase corresponds to the amorphous solubility while the dispersed phase is composed of a nanosized drug-rich phase. It has been reasoned that the drug-rich phase may act as a reservoir, enabling the rate of passive transport of the drug across a membrane to be maintained at the maximum value for an extended period of time. Herein, using clotrimazole as a model drug, and a flow-through diffusion cell, the reservoir effect is demonstrated. Supersaturated clotrimazole solutions at concentrations below the amorphous solubility show a linear relationship between the maximum flux and the initial concentration. Once the concentration exceeds the amorphous solubility, the maximum flux achieved reaches a plateau. However, the duration for which the high flux persists was found to be highly dependent on the number of drug-rich nanodroplets present in the donor compartment. Macroscopic amorphous particles of clotrimazole did not lead to the same reservoir effect observed with the nanodroplets formed through the process of LLPS. A first-principles mathematical model was developed which was able to fit the experimental receiver concentration-time profiles for concentration regimes both below and above amorphous solubility, providing support for the contention that the nanodroplet phase does not directly diffuse across the membrane but, instead, rapidly replenishes the drug in the aqueous phase that has been removed by transport across the membrane. This study provides important insight into the properties of

  20. Effects of cholesterol on phospholipid membranes: inhibition of the interdigitated gel phase of F-DPPC and F-DPPC/DPPC.

    Science.gov (United States)

    Smith, Eric A; Wang, Weidong; Dea, Phoebe K

    2012-02-01

    Unlike the parent phospholipid, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), the monofluorinated analog, 1-palmitoyl-2-(16-fluoropalmitoyl)sn-glycero-3-phosphocholine (F-DPPC), spontaneously forms an interdigitated gel phase (L(β)I) below the main transition temperature (T(m)). We have examined the effects of introducing cholesterol to F-DPPC and 1:1 F-DPPC/DPPC membranes using a combination of DSC, optical density, fluorescence intensity and polarization, (31)P NMR, and X-ray diffraction techniques. Cholesterol increases the fluidity of the gel phase, broadens the main transition, and decreases the main transition enthalpy. However, these results also reveal that there is an unusually large degree of phase coexistence between the L(β)I and non-interdigitated gel phases when cholesterol is added. Cholesterol encourages this phase segregation by partitioning into the thicker non-interdigitated domains. At higher cholesterol concentrations, the majority or all of the L(β)I phase of F-DPPC and 1:1 F-DPPC/DPPC is eliminated and is replaced by a non-interdigitated liquid-ordered (l(o)) phase with properties similar to DPPC/cholesterol. Consequently, cholesterol mitigates the influence the CF moiety has on the thermodynamic phase behavior of F-DPPC. Our findings demonstrate that there are multiple characteristics of cholesterol-rich membranes that disfavor interdigitation.

  1. X-ray scattering study of pike olfactory nerve: intensity of the axonal membrane, solution of the phase problem and electron density profile.

    Science.gov (United States)

    Luzzati, Vittorio; Vachette, Patrice; Benoit, Evelyne; Charpentier, Gilles

    2004-10-08

    Synchrotron radiation X-ray scattering experiments were performed on unmyelinated pike olfactory nerves. The difference between the meridional and the equatorial traces of the 2-D spectra yielded the 1-D equatorial intensity of the macromolecular components oriented with respect to the nerve: axonal membranes, microtubules and other cytoskeletal filaments. These 1-D spectra display a diffuse band typical of bilayer membranes and, at small s, a few sharper bands reminiscent of microtubules. All the spectra merge at large s. The intensity of the axonal membrane was determined via a noise analysis of the nerve-dependent spectra, involving also the notion that the thickness of the membrane is finite. The shape of the intensity function indicated that the electron density profile is not centrosymmetric. The knowledge of intensity and thickness paved the way to the electron density profile via an ab initio solution of the phase problem. An iterative procedure was adopted: (i) choose the lattice D of a 1-D pseudo crystal, interpolate the intensity at the points sh = h/D, adopt an arbitrary set of initial phases and compute the profile; (ii) determine the phases corresponding to this profile truncated by the thickness D/2; (iii) repeat the operation with the updated phases until a stable result is obtained. This iterative procedure was carried out for different D-values, starting in each case from randomly generated phases: stable results were obtained in less than 10,000 iterations. Most importantly, for D in the vicinity of 200 A, the overwhelming majority of the profiles were congruent with each other. These profiles were strongly asymmetric and otherwise typical of biological membranes.

  2. Effects of Additives and Coagulant Temperature on Fabrication of High Performance PVDF/Pluronic F127 Blend Hollow Fiber Membranes via Nonsolvent Induced Phase Separation

    Institute of Scientific and Technical Information of China (English)

    Chun Heng Loh; Rong Wang

    2012-01-01

    Poly(vinylidene fluoride) (PVDF) has become one of the most popular materials for membrane preparation via nonsolvent induced phase separation (NIPS) process. In this study, an amphiphilic block copolymer, Pluronic F127, has been used as both a pore-former and a surface-modifier in the fabrication of PVDF hollow fibermembranes to enhance the membrane permeability and hydrophilicity. The effects of 2nd additive and coagulant temperature on the formation of PVDF/Pluronic F 127 membranes have also been investigated. The as-spun hollow fibers were characterized in terms of cross-sectional morphology, pure water permeation (PWP), relative molecular mass cut-off (MWCO), membrane chemistry, and hydrolphilicity. It was obsered that the addition of Pluronic F 127 significantly increased the PWP of as-spun fibers, while the membrane contact angle was reduced. However, the size of macrovoids in the membranes was undesirably large. The addition of a 2nd additive, including lithium chloride (LiC1) and water, or an increase in coagulant temperature was found to effectively suppress the macrovoid for- mation in the Pluronic-containing membranes. In addition, the use of LiC1 as a 2nd additive also further enhanced the PWP and hydrophilicity of the membranes, while the surface pore size became smaller. PVDF hollow fiber with a PWP as high as 2330 L·m-2·h-1·MPa-1, a MWCO of 53000 and'a contact angle of 71 o was successfully fabricated with 3% (by mass) of Pluronic F127 and 3% (by mass) of LiC1 at a coagulant temperature of 25 ℃, which shows better performance as compared with most of PVDF hollow fiber membranes made by NIPS method.

  3. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-08-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Modeling of the isotopic transients on operating membranes (LSCrF-2828 at 900 C) and a ''frozen'' isotope profile have been analyzed in conjunction with a 1-D model to reveal the gradient in oxygen diffusivity through the membrane under conditions of high chemical gradients.

  4. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. The in situ electrical conductivity and Seebeck coefficient measurements were made on LSFT at 1000 and 1200 C over the oxygen activity range from air to 10{sup -15} atm. The electrical conductivity measurements exhibited a p to n type transition at an oxygen activity of 1 x 10{sup -10} at 1000 C and 1 x 10{sup -6} at 1200 C. Thermogravimetric studies were also carried out over the same oxygen activities and temperatures. Based on the results of these measurements, the chemical and mechanical stability range of LSFT were determined and defect structure was established. The studies on the fracture toughness of the LSFT and dual phase membranes exposed to air and N{sub 2} at 1000 C was done and the XRD and SEM analysis of the specimens were carried out to understand the structural and microstructural changes. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affect the mechanical properties. A complete transformation of fracture behavior was observed in the N{sub 2} treated LSFT samples. Further results to investigate the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Recent results on transient kinetic data are presented. The 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model is used to study ''frozen'' profiles in patterned or composite membranes.

  5. Active fluidization in dense glassy systems.

    Science.gov (United States)

    Mandal, Rituparno; Bhuyan, Pranab Jyoti; Rao, Madan; Dasgupta, Chandan

    2016-07-20

    Dense soft glasses show strong collective caging behavior at sufficiently low temperatures. Using molecular dynamics simulations of a model glass former, we show that the incorporation of activity or self-propulsion, f0, can induce cage breaking and fluidization, resulting in the disappearance of the glassy phase beyond a critical f0. The diffusion coefficient crosses over from being strongly to weakly temperature dependent as f0 is increased. In addition, we demonstrate that activity induces a crossover from a fragile to a strong glass and a tendency of active particles to cluster. Our results are of direct relevance to the collective dynamics of dense active colloidal glasses and to recent experiments on tagged particle diffusion in living cells.

  6. Topological Surface States in Dense Solid Hydrogen.

    Science.gov (United States)

    Naumov, Ivan I; Hemley, Russell J

    2016-11-11

    Metallization of dense hydrogen and associated possible high-temperature superconductivity represents one of the key problems of physics. Recent theoretical studies indicate that before becoming a good metal, compressed solid hydrogen passes through a semimetallic stage. We show that such semimetallic phases predicted to be the most stable at multimegabar (∼300  GPa) pressures are not conventional semimetals: they exhibit topological metallic surface states inside the bulk "direct" gap in the two-dimensional surface Brillouin zone; that is, metallic surfaces may appear even when the bulk of the material remains insulating. Examples include hydrogen in the Cmca-12 and Cmca-4 structures; Pbcn hydrogen also has metallic surface states but they are of a nontopological nature. The results provide predictions for future measurements, including probes of possible surface superconductivity in dense hydrogen.

  7. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-05-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, in situ neutron diffraction was used to characterize the chemical and structural properties of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} (here after as L2SF55T) specimen, which was subject to measurements of neutron diffraction from room temperature to 900 C. It was found that space group of R3c yielded a better refinement than a cubic structure of Pm3m. Oxygen occupancy was nearly 3 in the region from room temperature to 700 C, above which the occupancy decreased due to oxygen loss. Dense OTM bars provided by Praxair were loaded to fracture at varying stress rates. Studies were done at room temperature in air and at 1000 C in a specified environment to evaluate slow crack growth behavior. The X-Ray data and fracture mechanisms points to non-equilibrium decomposition of the LSFCO OTM membrane. The non-equilibrium conditions could probably be due to the nature of the applied stress field (stressing rates) and leads to transition in crystal structures and increased kinetics of decomposition. The formations of a Brownmillerite or Sr2Fe2O5 type structures, which are orthorhombic are attributed to the ordering of oxygen vacancies. The cubic to orthorhombic transitions leads to 2.6% increase in strains and thus residual stresses generated could influence the fracture behavior of the OTM membrane. Continued investigations on the thermodynamic properties (stability and phase-separation behavior) and total conductivity of prototype membrane materials were carried out. The data are needed together with the kinetic information to develop a complete model for the membrane transport. Previously characterization, stoichiometry and conductivity measurements for samples of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} were reported. In this report

  8. Study on Ultrasound-enhanced Dense Phase Carbon Dioxide Extraction of Sunflower Seed Oil%超声强化密相CO2萃取葵花籽油的研究

    Institute of Scientific and Technical Information of China (English)

    谭伟; 丘泰球; 范晓丹

    2007-01-01

    进行了超声强化密相CO2萃取葵花籽油的研究,探讨了萃取温度、压力、时间、CO2流速以及超声功率密度和频率对葵花籽油萃取率的影响.结果表明,附加20 kHz、100 W·L-1的超声波后,萃取压力、时间和CO2流速分别降低了5 MPa、0.5 h和0.5 L·h-1.超声对萃取的影响主要是由于超声的机械波动效应.采用了响应曲面法对超声强化萃取条件进行了优化,并得到优化后的萃取条件为:萃取温度28.3℃、压力28 MPa、时间178 min、CO2流速3.0 L·h-1、超声功率密度为100 W·L-1、超声频率为20 kHz.在优化条件下,UDCE与DCE相比能够提高19%的萃取率.%In this work, the effects of ultrasonic power density and frequency as well as extraction temperature, pressure, time and CO2 flow rate on the ultrasound-enhanced dense phase carbon dioxide extraction(UDCE) of sunflower seed oil are evaluated. Results show that extraction pressure, time and CO2 flow rate can be diminished by 5 MPa, 0.5 h and 0.5 L·h-1 with ultrasound. Effects of ultrasound on the extraction are due to the vibration. Response surface methodology is used to optimize the operating conditions, which are determined as follows: temperature 28.3℃, pressure 28 MPa, time 178 min,CO2 flow rate 3.0 L·h-1, ultrasonic power density 100 W·L-1 and ultrasonic frequency 20 kHz, respectively. Compared with DCE, UDCE can increase the extraction yield by 19% under optimum conditions.

  9. FCS diffusion laws in two-phase lipid membranes: determination of domain mean size by experiments and Monte Carlo simulations.

    Science.gov (United States)

    Favard, Cyril; Wenger, Jérôme; Lenne, Pierre-François; Rigneault, Hervé

    2011-03-02

    Many efforts have been undertaken over the last few decades to characterize the diffusion process in model and cellular lipid membranes. One of the techniques developed for this purpose, fluorescence correlation spectroscopy (FCS), has proved to be a very efficient approach, especially if the analysis is extended to measurements on different spatial scales (referred to as FCS diffusion laws). In this work, we examine the relevance of FCS diffusion laws for probing the behavior of a pure lipid and a lipid mixture at temperatures below, within and above the phase transitions, both experimentally and numerically. The accuracy of the microscopic description of the lipid mixtures found here extends previous work to a more complex model in which the geometry is unknown and the molecular motion is driven only by the thermodynamic parameters of the system itself. For multilamellar vesicles of both pure lipid and lipid mixtures, the FCS diffusion laws recorded at different temperatures exhibit large deviations from pure Brownian motion and reveal the existence of nanodomains. The variation of the mean size of these domains with temperature is in perfect correlation with the enthalpy fluctuation. This study highlights the advantages of using FCS diffusion laws in complex lipid systems to describe their temporal and spatial structure.

  10. Novel membrane bioreactor with gas/liquid two-phase flow for high-performance degradation of phenol

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, D.; Mercier-Bonin, M.; Lindley, N.D.; Lafforgue, C. [Inst. National des Sciences Appliquees, Toulouse (France)

    1998-09-01

    The use of a membrane bioreactor with cell retention to achieve high biomass concentrations has been examined for phenol degradation by the bacteria Alcaligenes eutrophus. This process is particularly interesting for toxic substrates as the hydraulic dilution rate and the growth rate are independently controlled. In the case of a transitory excess of phenol, this potentially toxic situation can be overcome by modifying the substrate concentration or the dilute rate without any loss of cells. The injection of a gas phase at the filter inlet increased both the permeate flow rate and the oxygen transfer capacity. This has enabled the cell concentration to reach a maximum value of 60 g L{sup {minus}1} with a hydraulic dilution rate of 0.5 h{sup {minus}1} and a phenol feed concentration of 8 g L{sup {minus}1}. The volumetric productivity of this process corresponds to a phenol degradation rate approaching 100 kg m{sup {minus}3} day{sup {minus}1}. The on-line measurement of the characteristic yellow color of 2-hydroxymuconate semialdehyde, a metabolic intermediate of the phenol degradation pathway, in the permeate provides an interesting basis for process control of phenol supply into the reactor since the color intensity correlates directly to the specific rate of phenol degradation.

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-01-01

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

  12. Modeling two-phase flow in three-dimensional complex flow-fields of proton exchange membrane fuel cells

    Science.gov (United States)

    Kim, Jinyong; Luo, Gang; Wang, Chao-Yang

    2017-10-01

    3D fine-mesh flow-fields recently developed by Toyota Mirai improved water management and mass transport in proton exchange membrane (PEM) fuel cell stacks, suggesting their potential value for robust and high-power PEM fuel cell stack performance. In such complex flow-fields, Forchheimer's inertial effect is dominant at high current density. In this work, a two-phase flow model of 3D complex flow-fields of PEMFCs is developed by accounting for Forchheimer's inertial effect, for the first time, to elucidate the underlying mechanism of liquid water behavior and mass transport inside 3D complex flow-fields and their adjacent gas diffusion layers (GDL). It is found that Forchheimer's inertial effect enhances liquid water removal from flow-fields and adds additional flow resistance around baffles, which improves interfacial liquid water and mass transport. As a result, substantial improvements in high current density cell performance and operational stability are expected in PEMFCs with 3D complex flow-fields, compared to PEMFCs with conventional flow-fields. Higher current density operation required to further reduce PEMFC stack cost per kW in the future will necessitate optimizing complex flow-field designs using the present model, in order to efficiently remove a large amount of product water and hence minimize the mass transport voltage loss.

  13. Phase I Safety and Immunogenicity Study of a Candidate Meningococcal Disease Vaccine Based on Neisseria lactamica Outer Membrane Vesicles▿

    Science.gov (United States)

    Gorringe, Andrew R.; Taylor, Stephen; Brookes, Charlotte; Matheson, Mary; Finney, Michelle; Kerr, Moyra; Hudson, Michael; Findlow, Jamie; Borrow, Ray; Andrews, Nick; Kafatos, George; Evans, Cariad M.; Read, Robert C.

    2009-01-01

    Natural immunity to meningococcal disease in young children is associated epidemiologically with carriage of commensal Neisseria species, including Neisseria lactamica. We have previously demonstrated that outer membrane vesicles (OMVs) from N. lactamica provide protection against lethal challenge in a mouse model of meningococcal septicemia. We evaluated the safety and immunogenicity of an N. lactamica OMV vaccine in a phase I placebo-controlled, double-blinded clinical trial. Ninety-seven healthy young adult male volunteers were randomized to receive three doses of either an OMV vaccine or an Alhydrogel control. Subsequently, some subjects who had received the OMV vaccine also received a fourth dose of OMV vaccine, 6 months after the third dose. Injection site reactions were more frequent in the OMV-receiving group, but all reactions were mild or moderate in intensity. The OMV vaccine was immunogenic, eliciting rises in titers of immunoglobulin G (IgG) against the vaccine OMVs, together with a significant booster response, as determined by an enzyme-linked immunosorbent assay. Additionally, the vaccine induced modest cross-reactive immunity to six diverse strains of serogroup B Neisseria meningitidis, including IgG against meningococcal OMVs, serum bactericidal antibodies, and opsonophagocytic activity. The percentages of subjects showing ≥4-fold rises in bactericidal antibody titer obtained were similar to those previously reported for the Norwegian meningococcal OMV vaccine against the same heterologous meningococcal strain panel. In conclusion, this N. lactamica OMV vaccine is safe and induces a weak but broad humoral immune response to N. meningitidis. PMID:19553555

  14. Phase I safety and immunogenicity study of a candidate meningococcal disease vaccine based on Neisseria lactamica outer membrane vesicles.

    Science.gov (United States)

    Gorringe, Andrew R; Taylor, Stephen; Brookes, Charlotte; Matheson, Mary; Finney, Michelle; Kerr, Moyra; Hudson, Michael; Findlow, Jamie; Borrow, Ray; Andrews, Nick; Kafatos, George; Evans, Cariad M; Read, Robert C

    2009-08-01

    Natural immunity to meningococcal disease in young children is associated epidemiologically with carriage of commensal Neisseria species, including Neisseria lactamica. We have previously demonstrated that outer membrane vesicles (OMVs) from N. lactamica provide protection against lethal challenge in a mouse model of meningococcal septicemia. We evaluated the safety and immunogenicity of an N. lactamica OMV vaccine in a phase I placebo-controlled, double-blinded clinical trial. Ninety-seven healthy young adult male volunteers were randomized to receive three doses of either an OMV vaccine or an Alhydrogel control. Subsequently, some subjects who had received the OMV vaccine also received a fourth dose of OMV vaccine, 6 months after the third dose. Injection site reactions were more frequent in the OMV-receiving group, but all reactions were mild or moderate in intensity. The OMV vaccine was immunogenic, eliciting rises in titers of immunoglobulin G (IgG) against the vaccine OMVs, together with a significant booster response, as determined by an enzyme-linked immunosorbent assay. Additionally, the vaccine induced modest cross-reactive immunity to six diverse strains of serogroup B Neisseria meningitidis, including IgG against meningococcal OMVs, serum bactericidal antibodies, and opsonophagocytic activity. The percentages of subjects showing > or =4-fold rises in bactericidal antibody titer obtained were similar to those previously reported for the Norwegian meningococcal OMV vaccine against the same heterologous meningococcal strain panel. In conclusion, this N. lactamica OMV vaccine is safe and induces a weak but broad humoral immune response to N. meningitidis.

  15. Novel solid-phase membrane tip extraction and gas chromatography with mass spectrometry methods for the rapid analysis of triazine herbicides in real waters.

    Science.gov (United States)

    Sanagi, Mohd Marsin; Muhammad, Sarmad S; Hussain, Iqbal; Ibrahim, Wan Aini Wan; Ali, Imran

    2015-02-01

    Novel, fast, selective, eco-friendly and reproducible solid-phase membrane tip extraction and gas chromatography with mass spectrometry methods were developed and validated for the analysis of triazine herbicides (atrazine and secbumeton) in stream and lake waters. The retention times of atrazine and secbumeton were 7.48 and 8.51 min. The solid-phase membrane tip extraction was carried out in semiautomated dynamic mode on multiwall carbon nanotubes enclosed in a cone-shaped polypropylene membrane cartridge. Acetone and methanol were found as the best preconditioning and desorption solvents, respectively. The extraction and desorption times for these herbicides were 15.0 and 10.0 min, respectively. The percentage recoveries of atrazine and secbumeton were 88.0 and 99.0%. The linearity range was 0.50-80.0 μg/L (r(2) > 0.994), with detection limits (extraction made these methods novel. The Solid-phase membrane tip extraction method was optimized by considering the effect of extraction time, desorbing solvents and time.

  16. Improved performance of polyvinylidenefluoride-hexafluoropropylene based nanocomposite polymer membranes containing lithium bis(oxalato)borate by phase inversion for lithium batteries

    Science.gov (United States)

    Aravindan, V.; Vickraman, P.; Madhavi, S.; Sivashanmugam, A.; Thirunakaran, R.; Gopukumar, S.

    2011-05-01

    Nanocomposite polymer electrolyte membranes were prepared by phase inversion technique in polyvinylidenefluoride-hexafluoropropylene (PVdF-HFP) matrix. These membranes were gelled with 0.5 M LiBOB in EC:DEC (1:1 v/v). These gel polymer membranes (GPMs) were incorporated with nanoparticles of AlO(OH) n and prepared composite polymer membranes (CPMs) also. The a.c. impedance analysis shows that AlO(OH) n filled membrane exhibits conductivity of 1.82 × 10 -3 S cm -1 at ambient temperature. The Li/CPM/LiFePO 4 cell delivered a specific discharge capacity of 158 and 147 mAh g -1 at first and at 20th cycle respectively discharged at C/20 rate. The cell experiences a capacity fade of 0.1 mAh g -1 cycle -1 over the investigated 20 cycles. The studies vindicate that AlO(OH) n filled PVdF-HFP polymer membranes could be the potential material to use as separator cum electrolyte in lithium batteries in conjunction with LiFePO 4 as a counterpart.

  17. Mechanics of dense suspensions in turbulent channel flows

    NARCIS (Netherlands)

    Picano, F.; Costa, P.; Breugem, W.P.; Brandt, L.

    2015-01-01

    Dense suspensions are usually investigated in the laminar limit where inertial effects are insignificant. When the flow rate is high enough, i.e. at high Reynolds number, the flow may become turbulent and the interaction between solid and liquid phases modifies the turbulence we know in single-phase

  18. Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas, Phase 1. [Polyetherimide, cellulose acetate and ethylcellulose

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    The goal of this program is to develop polymer membranes useful in the preparation of hydrogen from coal-derived synthesis gas. During this quarter the first experiment were aimed at developing high performance composite membranes for the separation of hydrogen from nitrogen and carbon monoxide. Three polymers have been selected as materials for these membranes: polyetherimide cellulose acetate and ethylcellulose. This quarter the investigators worked on polyetherimide and cellulose acetate membranes. The overall structure of these membranes is shown schematically in Figure 1. As shown, a microporous support membrane is first coated with a high flux intermediate layer then with an ultrathin permselective layer and finally, if necessary, a thin protective high flux layer. 1 fig., 4 tabs.

  19. A strategy for the systematic development of a liquid chromatographic mass spectrometric screening method for polymer electrolyte membrane degradation products using isocratic and gradient phase optimized liquid chromatography.

    Science.gov (United States)

    Zedda, M; Tuerk, J; Teutenberg, T; Peil, S; Schmidt, T C

    2009-12-18

    Within the scope of research for target and non-target LC-MS/MS analysis of membrane degradation products of polymer electrolyte membrane fuel cells, a systematic method development for the separation of structurally similar compounds was performed by phase optimized liquid chromatography. Five different stationary phases with different selectivities were used. Isocratic separation for 4-hydroxybenzoic acid, isophthalic acid, terephthalic acid, 4-hydroxybenzaldehyde and 4-formylbenzoic acid was achieved on a C18 and a Phenyl phase. Using the PRISMA model the separation efficiency was optimized. This was achieved on a serially connected mixed stationary phase composed of 30 mm C18, 150 mm Phenyl and 60 mm C30. For the LC-MS screening of unknown degradation products from polymer electrolyte membranes in the product water of a fuel cell, a solvent gradient is mandatory for less polar or later eluting compounds. By means of 4-mercaptobenzoic acid it could be shown that a solvent gradient can be applied in order to elute later eluting compounds in a short time. The adaptability of this method for the qualitative analysis by target and non-target LC-MS/MS screening has been shown by means of 4-hydroxybenzoic acid. The combination of solvent gradient and isocratic conditions makes this approach attractive for the purpose of a screening method for known and unknown analytes in a water sample.

  20. Effect of dry/wet-phase inversion method on fabricating polyetherimide-derived CMS membrane for H{sub 2}/N{sub 2} separation

    Energy Technology Data Exchange (ETDEWEB)

    Itta, Arun Kumar; Wey, Ming-Yen [Department of Environmental Engineering, National Chung Hsing University, Taichung 402 (China); Tseng, Hui-Hsin [School of Occupational Safety and Health, Chung Shan Medical University, Taichung 402 (China)

    2010-02-15

    The research investigated carbon molecular sieve (CMS) membranes through the dry/wet-phase inversion method from the casting polyetherimide (PEI) on alumina support for hydrogen separation. Different coating techniques such as dry method (slide casting followed by drying under vacuum; and spin coating followed by drying under vacuum); and wet method (spin coating and then later kept in an isopropyl alcohol (IPA)/water coagulating bath) at different pyrolysis temperatures of 550, 600, 650 C min{sup -1} were also investigated. The membranes were extensively characterized by field emission scanning electron microscopy (FE-SEM) for surface morphology studies and thermo gravimetric analysis (TGA) for thermal properties. The best performance was obtained from CMS membranes fabricated with the dry-phase method (slide casting/vacuum) and pyrolysis at 600 C, where the H{sub 2}/N{sub 2} permselectivity was 16.2. In contrast with the wet-phase, the increase in gas permselectivity by the dry-phase (slide casting/vacuum) was believed to be due to the quick solidification that prevents rearrangement of polymer aggregates and coalescence of the nascent voids formed due to the spinodal or nucleation growth. (author)

  1. Densely crosslinked polycarbosiloxanes .1. Synthesis

    NARCIS (Netherlands)

    Flipsen, T.A C; Derks, R.; van der Vegt, H.A.; Pennings, A.J; Hadziioannou, G

    1997-01-01

    Novel densely crosslinked polycarbosiloxanes were obtained by using functional branched prepolymers. Two types of soluble prepolymers were prepared from di- and trifunctional alkoxysilane monomers via cohydrolysis/condensation and for both final crosslinking occurred via hydrosilylation. The prepoly

  2. Interactions between oxygen permeation and homogeneous-phase fuel conversion on the sweep side of an ion transport membrane

    KAUST Repository

    Hong, Jongsup

    2013-02-01

    The interactions between oxygen permeation and homogeneous fuel oxidation reactions on the sweep side of an ion transport membrane (ITM) are examined using a comprehensive model, which couples the dependency of the oxygen permeation rate on the membrane surface conditions and detailed chemistry and transport in the vicinity of the membrane. We assume that the membrane surface is not catalytic to hydrocarbon or syngas oxidation. Results show that increasing the sweep gas inlet temperature and fuel concentration enhances oxygen permeation substantially. This is accomplished through promoting oxidation reactions (oxygen consumption) and the transport of the products and reaction heat towards the membrane, which lowers the oxygen concentration and increases the gas temperature near the membrane. Faster reactions at higher fuel concentration and higher inlet gas temperature support substantial fuel conversion and lead to a higher oxygen permeation flux without the contribution of surface catalytic activity. Beyond a certain maximum in the fuel concentration, extensive heat loss to the membrane (and feed side) reduces the oxidation kinetic rates and limits oxygen permeation as the reaction front reaches the membrane. The sweep gas flow rate and channel height have moderate impacts on oxygen permeation and fuel conversion due to the residence time requirements for the chemical reactions and the location of the reaction zone relative to the membrane surface. © 2012 Elsevier B.V.

  3. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite

    2014-01-01

    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes...... controlled by membrane structure, permeability and curvature as well as membrane proteins by using a wide range of biochemical, biophysical and microscopic techniques. This review gives an overview of some currently used model biomembrane systems. We will also discuss some key membrane protein properties...... that are relevant for protein-membrane interactions in terms of protein structure and how it is affected by membrane composition, phase behavior and curvature....

  4. Novel SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) membrane for hydrogen separation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Dense ceramic membranes with protonic and electronic conductivity have attracted considerable interest in recent years.In this paper,the powders of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were synthesized via the liquid citrate method,and the membranes of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were prepared by pressing followed by sintering.X-ray diffraction(XRD) was used to characterize the phase structure of both the powder and sintered membrane.The microstructure of the sintered membranes was studied by sc...

  5. Frontiers and challenges in warm dense matter

    CERN Document Server

    Desjarlais, Michael; Redmer, Ronald; Trickey, Samuel

    2014-01-01

    Warm Dense Matter (WDM) occupies a loosely defined region of phase space intermediate between solid, liquid, gas, and plasma, and typically shares characteristics of two or more of these phases. WDM is generally associated with the combination of strongly coupled ions and moderately degenerate electrons, and careful attention to quantum physics and electronic structure is essential. The lack of a small perturbation parameter greatly limits approximate attempts at its accurate description. Since WDM resides at the intersection of solid state and high energy density physics, many high energy density physics (HEDP) experiments pass through this difficult region of phase space. Thus, understanding and modeling WDM is key to the success of experiments on diverse facilities. These include the National Ignition Campaign centered on the National Ignition Facility (NIF), pulsed-power driven experiments on the Z machine, ion-beam-driven WDM experiments on the NDCX-II, and fundamental WDM research at the Linear Coherent...

  6. Automation of static and dynamic non-dispersive liquid phase microextraction. Part 2: Approaches based on impregnated membranes and porous supports.

    Science.gov (United States)

    Alexovič, Michal; Horstkotte, Burkhard; Solich, Petr; Sabo, Ján

    2016-02-11

    A critical overview on automation of modern liquid phase microextraction (LPME) approaches based on the liquid impregnation of porous sorbents and membranes is presented. It is the continuation of part 1, in which non-dispersive LPME techniques based on the use of the extraction phase (EP) in the form of drop, plug, film, or microflow have been surveyed. Compared to the approaches described in part 1, porous materials provide an improved support for the EP. Simultaneously they allow to enlarge its contact surface and to reduce the risk of loss by incident flow or by components of surrounding matrix. Solvent-impregnated membranes or hollow fibres are further ideally suited for analyte extraction with simultaneous or subsequent back-extraction. Their use can therefore improve the procedure robustness and reproducibility as well as it "opens the door" to the new operation modes and fields of application. However, additional work and time are required for membrane replacement and renewed impregnation. Automation of porous support-based and membrane-based approaches plays an important role in the achievement of better reliability, rapidness, and reproducibility compared to manual assays. Automated renewal of the extraction solvent and coupling of sample pretreatment with the detection instrumentation can be named as examples. The different LPME methodologies using impregnated membranes and porous supports for the extraction phase and the different strategies of their automation, and their analytical applications are comprehensively described and discussed in this part. Finally, an outlook on future demands and perspectives of LPME techniques from both parts as a promising area in the field of sample pretreatment is given.

  7. Oscillating propagators in heavy-dense QCD

    CERN Document Server

    Akerlund, Oscar; Rindlisbacher, Tobias

    2016-10-11

    Using Monte Carlo simulations and extended mean field theory calculations we show that the $3$-dimensional $\\mathbb{Z}_3$ spin model with complex external fields has non-monotonic correlators in some regions of its parameter space. This model serves as a proxy for heavy-dense QCD in $(3+1)$ dimensions. Non-monotonic correlators are intrinsically related to a complex mass spectrum and a liquid-like (or crystalline) behavior. A liquid phase could have implications for heavy-ion experiments, where it could leave detectable signals in the spatial correlations of baryons.

  8. The liquid phase epitaxy approach for the successful construction of ultra-thin and defect-free ZIF-8 membranes: Pure and mixed gas transport study

    KAUST Repository

    Shekhah, Osama

    2014-01-01

    The liquid-phase epitaxy (LPE) method was effectively implemented to deliberately grow/construct ultrathin (0.5-1 μm) continuous and defect-free ZIF-8 membranes. Permeation properties of different gas pair systems (O 2-N2, H2-CO2, CO2-CH 4, C3H6-C3H8, CH 4-n-C4H10) were studied using the time lag technique. This journal is © The Royal Society of Chemistry.

  9. Conductive dense hydrogen.

    Science.gov (United States)

    Eremets, M I; Troyan, I A

    2011-11-13

    Molecular hydrogen is expected to exhibit metallic properties under megabar pressures. This metal is predicted to be superconducting with a very high critical temperature, T(c), of 200-400 K, and it may acquire a new quantum state as a metallic superfluid and a superconducting superfluid. It may potentially be recovered metastably at ambient pressures. However, experiments carried out at low temperatures, Thydrogen remains in the molecular insulating state. Here we report on the transformation of normal molecular hydrogen at room temperature (295 K) to a conductive and metallic state. At 200 GPa the Raman frequency of the molecular vibron strongly decreased and the spectral width increased, evidencing a strong interaction between molecules. Deuterium behaved similarly. Above 220 GPa, hydrogen became opaque and electrically conductive. At 260-270 GPa, hydrogen transformed into a metal as the conductance of hydrogen sharply increased and changed little on further pressurizing up to 300 GPa or cooling to at least 30 K; and the sample reflected light well. The metallic phase transformed back at 295 K into molecular hydrogen at 200 GPa. This significant hysteresis indicates that the transformation of molecular hydrogen into a metal is accompanied by a first-order structural transition presumably into a monatomic liquid state. Our findings open an avenue for detailed and comprehensive studies of metallic hydrogen.

  10. Effects of dense phase carbon dioxide on muscle quality of Haliotis discus hannai%高密度CO2处理对皱纹盘鲍肌肉品质的影响

    Institute of Scientific and Technical Information of China (English)

    吕妙兄; 刘书成; 屈小娟; 章超桦; 吉宏武; 高加龙

    2013-01-01

      为了探讨高密度 CO2(DPCD)应用于加工皱纹盘鲍的可行性,在压力5~25 MPa、温度30~50℃、处理时间10~50 min下分别处理皱纹盘鲍,研究DPCD对其色泽、pH值、保水性、质量损失、质构等指标的影响规律。结果表明:与未处理的相比,DPCD处理对皱纹盘鲍的外观和pH值无显著影响(P>0.05),但对其色泽、基本营养成分、质量损失、保水性和质构有显著影响(P<0.05),并且随着处理强度的增加,其影响程度也加强;结合杀菌效果,DPCD处理皱纹盘鲍的适宜条件为:20 MPa、45℃、(40~50)min。研究结果将为DPCD加工技术在贝类肌肉食品中的应用提供参考。%Dense phase carbon dioxide (DPCD) is a non-thermal processing technology, which affects microorganisms and enzymes through molecular effects of CO2 under pressures below 50 MPa and 60 . DPCD℃has less significance effect on the quality of foods. DPCD has been applied to the process of meats, vegetables, seeds and food powders, fruits, spices and herbs, and fish. The studied objective is to investigate the effects of DPCD on bacteria inactivation and qualities of Haliotis discus hannai and to explore whether it can be applied to process Haliotis discus hannai. In this paper, the effects of pressure (5-25 MPa), exposure time (10-50 min) and temperature (30-50℃) of DPCD treatment on bacteria inactivation and qualities of Haliotis discus hannai were studied. DPCD can reach the ideal sterilizing effect for Haliotis discus hannai under the conditions of pressure 20MPa, temperature 45℃, exposure time 40-50 min. Compared with Haliotis discus hannai cooked in boiling water for 2 min (logarithmic decline of 3.59), the sterilizing effect was the equivalent by DPCD of 20 MPa and 45 for 40℃ -50 min (logarithmic decline of 3.46). The total number of colonies was less than 1000 cfu/mL. Compared with untreated Haliotis discus hannai, DPCD treatment had no

  11. Automated Motion Estimation for 2D Cine DENSE MRI

    Science.gov (United States)

    Gilliam, Andrew D.; Epstein, Frederick H.

    2013-01-01

    Cine displacement encoding with stimulated echoes (DENSE) is a magnetic resonance (MR) method that directly encodes tissue displacement into MR phase images. This technique has successfully interrogated many forms of tissue motion, but is most commonly used to evaluate cardiac mechanics. Currently, motion analysis from cine DENSE images requires manually delineated anatomical structures. An automated analysis would improve measurement throughput, simplify data interpretation, and potentially access important physiological information during the MR exam. In this article, we present the first fully automated solution for the estimation of tissue motion and strain from 2D cine DENSE data. Results using both simulated and human cardiac cine DENSE data indicate good agreement between the automated algorithm and the standard semi-manual analysis method. PMID:22575669

  12. A Green Method for Processing Polymers using Dense Gas Technology

    Directory of Open Access Journals (Sweden)

    Roshan B. Yoganathan

    2010-05-01

    Full Text Available Dense CO2 can be used as an environmentally-benign polymer processing medium because of its liquid-like densities and gas-like mass transfer properties.In this work, polymer bio-blends of polycarbonate (PC, a biocompatible polymer, and polycaprolactone (PCL, a biodegradable polymer were prepared. Dense CO2 was used as a reaction medium for the melt-phase PC polymerization in the presence of dense CO2-swollen PCL particles and this method was used to prepare porous PC/PCL blends. To extend the applicability of dense CO2 to the biomedical industry and polymer blend processing, the impregnation of ibuprofen into the blend was conducted and subsequent dissolution characteristics were observed.

  13. Supported Molten Metal Membranes for Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    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

  14. Electrochemical properties of honeycomb-like structured HFBI self-organized membranes on HOPG electrodes.

    Science.gov (United States)

    Yamasaki, Ryota; Takatsuji, Yoshiyuki; Lienemann, Michael; Asakawa, Hitoshi; Fukuma, Takeshi; Linder, Markus; Haruyama, Tetsuya

    2014-11-01

    HFBI (derived from Trichoderma sp.) is a unique structural protein, which forms a self-organized monolayer at both air/water interface and water/solid interfaces in accurate two-dimensional ordered structures. We have taken advantage of the unique functionality of HFBI as a molecular carrier for preparation of ordered molecular phase on solid substrate surfaces. The HFBI molecular carrier can easily form ordered structures; however, the dense molecular layers form an electrochemical barrier between the electrode and solution phase. In this study, the electrochemical properties of HFBI self-organized membrane-covered electrodes were investigated. Wild-type HFBI has balanced positive and negative charges on its surface. Highly oriented pyrolytic graphite (HOPG) electrodes coated with HFBI molecules were investigated electrochemically. To improve the electrochemical properties of this HFBI-coated electrode, the two types of HFBI variants, with oppositely charged surfaces, were prepared genetically. All three types of HFBI-coated HOPG electrode perform electron transfer between the electrode and solution phase through the dense HFBI molecular layer. This is because the HFBI self-organized membrane has a honeycomb-like structure, with penetrating holes. In the cases of HFBI variants, the oppositely charged HFBI membrane phases shown opposite electrochemical behaviors in electrochemical impedance spectroscopy. HFBI is a molecule with a unique structure, and can easily form honeycomb-like structures on solid material surfaces such as electrodes. The molecular membrane phase can be used for electrochemical molecular interfaces.

  15. 稠密可压缩气粒两相流动中的等熵声速计算建模及物理规律∗%On mo deling and physical laws of isentropic sp eed of sound in dense gas-particle two-phase compressible flows

    Institute of Scientific and Technical Information of China (English)

    陈大伟; 王裴; 蔚喜军; 孙海权; 马东军

    2016-01-01

    Study of isentropic sound speed of two-phase or multiphase flow has theoretical significance and wide application background. As is well known, the speed of sound in fluid containing particles in suspension differs from that in the pure fluid. In the particular case of bubbly liquids (gas liquid two-phase flow), the researches find that the differences can be drastic. Up to now, the isentropic speed of sound in the flow field with a small volume fraction of bubbles (less than 1%), has been investigated fully both experimentally and theoretically. In this paper, we consider another situation, as the case with solid particles in gas, which is the so-called gas particle two-phase flow. Although many results have been obtained in gas liquid two-phase flow, there is still a lot of basic work to do due to the large differences in the flow structure and flow pattern between gas particle two-phase flow and gas liquid two-phase flow. Treating the gas particle suspension as the relaxed equilibrium, thermodynamic arguments are used to obtain the isentropic speed of sound. Unlike the existing work, we are dedicated to developing the computational model under dense condition. The space volume occupied by particle phase and the interaction between particles are overall considered, then a new formula of isentropic sound speed is derived. The new formula includes formulae of the pure gas flow and the already existing dilute gas particle two-phase flow as a special case. On the one hand, the correctness of our formula is verified. On the other hand, the new formula is more general. The variations of sound speed with different mass fractions of particle phase are analyzed. The theoretical calculation results show that the overall physical law of sound speed change is that with the increase of the particle mass fraction, the sound speed first decreases and then increases. The velocity of sound propagation in gas particle two-phase flow is far smaller than in pure gas in a wide range

  16. Silence of Synaptotagmin VII inhibits release of dense core vesicles in PC12 cells

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Synaptotagmin VII (Syt VII), which has a higher Ca2+ affinity and slower disassembly kinetics with lipid than Syt I and Syt IX, was regarded as being uninvolved in synaptic vesicle (SV) exocytosis but instead possibly as a calcium sensor for the slower kinetic phase of dense core vesicles (DCVs) release. By using high temporal resolution capacitance and amperometry measurements, it was demonstrated that the knockdown of endogenous Syt VII attenuated the fusion of DCV with the plasma membrane, reduced the amplitude of the exocytotic burst of the Ca2+-triggered DCV release without affecting the slope of the sustained component, and blocked the fusion pore expansion. This suggests that Syt VII is the Ca2+ sensor of DCV fusion machinery and is an essential factor for the establishment and maintenance of the pool size of releasable DCVs in PC12 cells.

  17. Ion Beam Driven Warm Dense Matter Experiments

    Science.gov (United States)

    Bieniosek, F. M.; Henestroza, E.; Leitner, M. A.; Lidia, S. M.; Logan, B. G.; More, R. M.; Ni, P. A.; Seidl, P. A.; Waldron, W. L.; Barnard, J. J.

    2008-11-01

    We report plans and experimental results in ion beam-driven warm dense matter (WDM) experiments. Initial experiments use a 0.3 MeV K+ beam from the NDCX-I accelerator. The WDM conditions are to be achieved by longitudinal and transverse neutralized drift compression to provide a hot spot on the target with a 1-mm beam spot size, and 2-ns pulse length. As a technique for heating matter to high energy density, intense ion beams can deliver precise and uniform beam energy deposition, in a relatively large sample size, and can heat any solid-phase target material. The range of the beams in solid targets is less than 1 micron, which can be lengthened by using reduced density porous targets. We have developed a WDM target chamber and target diagnostics including a fast multi-channel optical pyrometer, optical streak camera, VISAR, and high-speed gated cameras. Initial experiments will explore measurement of temperature and other target parameters. Experiments are planned in areas such as dense electronegative targets, porous target homogenization and two-phase equation of state.

  18. A membrane bioreactor for the removal of dimethyl sulphide and toluene from waste air.

    Science.gov (United States)

    Van Langenhove, H; De Bo, I; Jacobs, P; Demeestere, K; Dewulf, J

    2004-01-01

    In biotrickling filters, mass transfer of hydrophobic compounds is the limiting factor. Biofilters are static systems, and so control and regulation of operational parameters such as pH and nutrient supply can be a problem. In membrane bioreactors, these drawbacks can be avoided. The hydrophobic membrane separates the waste air from the aqueous phase, thus avoiding mass-transfer limitation, while pH and nutrient supply can be directly controlled. In this contribution, an overview will be given of results obtained during a four-year project. First, the physical chemical characteristics (solubility, permeability, diffusivity) and microbial adhesion of different membranes were tested. This led to the selection of a composite membrane consisting of a porous polyvinylidenefluoride (PVDF) support layer coated with a thin (1 or 2.5 microm) dense polydimethylsiloxane (PDMS) top layer. This membrane was mounted into a module provided with four parallel rectangular channels for gas flow (in contact with the porous layer) and nutrient solution (in contact with the dense layer) respectively. After inoculation, a biofilm developed on the dense layer. Experiments were performed with dimethyl sulphide and toluene as target VOCs. Operational characteristics such as elimination capacity as a function of the volumetric load and residence time, effect of nutrient supply, long-term performance) were determined. Mass transfer was studied by measuring concentration profiles along the channels of the module in different conditions.

  19. One-Step Synthesis of Cross-Linked Ionic Polymer Thin Films in Vapor Phase and Its Application to an Oil/Water Separation Membrane.

    Science.gov (United States)

    Joo, Munkyu; Shin, Jihye; Kim, Jiyeon; You, Jae Bem; Yoo, Youngmin; Kwak, Moo Jin; Oh, Myung Seok; Im, Sung Gap

    2017-02-15

    In spite of the huge research interest, ionic polymers could not have been synthesized in the vapor phase because the monomers of ionic polymers contain nonvolatile ionic salts, preventing the monomers from vaporization. Here, we suggest a new, one-step synthetic pathway to form a series of cross-linked ionic polymers (CIPs) in the vapor phase via initiated chemical vapor deposition (iCVD). 2-(Dimethylamino)ethyl methacrylate (DMAEMA) and 4-vinylbenzyl chloride (VBC) monomers are introduced into the iCVD reactor in the vapor phase to form a copolymer film. Simultaneously in the course of the deposition process, the tertiary amine in DMAEMA and benzylic chloride in VBC undergo a Menshutkin nucleophilic substitution reaction to form an ionic ammonium-chloride complex, forming a highly cross-linked ionic copolymer film of p(DMAEMA-co-VBC). To the best of our knowledge, this is the first report on the synthesis of CIP films in the vapor phase. The newly developed CIP thin film is further applied to the surface modification of the membrane for oil/water separation. With the hydrophilic and underwater oleophobic membrane whose surface is modified with the CIP film, excellent separation efficiency (>99%) and unprecedentedly high permeation flux (average 2.32 × 10(5) L m(-2) h(-1)) are achieved.

  20. Final results of a phase I/II pilot study of capecitabine with or without vinorelbine after sequential dose-dense epirubicin and paclitaxel in high-risk early breast cancer

    Directory of Open Access Journals (Sweden)

    Müller Volkmar

    2010-08-01

    Full Text Available Abstract Background The integration of the non-cross-resistant chemotherapeutic agents capecitabine and vinorelbine into an intensified dose-dense sequential anthracycline- and taxane-containing regimen in high-risk early breast cancer (EBC could improve efficacy, but this combination was not examined in this context so far. Methods Patients with stage II/IIIA EBC (four or more positive lymph nodes received post-operative intensified dose-dense sequential epirubicin (150 mg/m² every 2 weeks and paclitaxel (225 mg/m² every 2 weeks with filgrastim and darbepoetin alfa, followed by capecitabine alone (dose levels 1 and 3 or with vinorelbine (dose levels 2 and 4. Capecitabine was given on days 1-14 every 21 days at 1000 or 1250 mg/m2 twice daily (dose levels 1/2 and 3/4, respectively. Vinorelbine 25 mg/m2 was given on days 1 and 8 of each 21-day course (dose levels 2 and 4. Results Fifty-one patients were treated. There was one dose-limiting toxicity (DLT at dose level 1. At dose level 2 (capecitabine and vinorelbine, five of 10 patients experienced DLTs. Therefore evaluation of vinorelbine was abandoned and dose level 3 (capecitabine monotherapy was expanded. Hand-foot syndrome and diarrhoea were dose limiting with capecitabine 1250 mg/m2 twice daily. At 35.2 months' median follow-up, the estimated 3-year relapse-free and overall survival rates were 82% and 91%, respectively. Conclusions Administration of capecitabine monotherapy after sequential dose-dense epirubicin and paclitaxel is feasible in node-positive EBC, while the combination of capecitabine and vinorelbine as used here caused more DLTs. Trial registration Current Controlled Trials ISRCTN38983527.

  1. Microsequencing of proteins and peptides in the Knauer sequencer with and without covalent attachment to polyvinylidene difluoride membranes by the wet-phase degradation technique.

    Science.gov (United States)

    Herfurth, E; Pilling, U; Wittmann-Liebold, B

    1991-05-01

    Proteins and large peptides were degraded with phenylisothiocyanate (PITC) in the horizontal flow-through-reactor of the Modular Knauer Sequencer (Fischer, S., Reimann, F. & Wittmann-Liebold, B. (1989) in Methods in Protein Sequence Analysis (Wittmann-Liebold, B., ed.) Springer-Verlag, Berlin, pp. 98-107) by the wet-phase filter technique (Wittmann-Liebold, B. (1988) J. Prot. Chem. 7, 224-225) employing polyvinylidene difluoride (PVDF) membranes without polybrene. In order to prevent losses of small peptides during solvent washes at the degradation, 1.4-phenylene diisothiocyanate (DITC) derivatized PVDF support (MilliGen, Burlington, MA) was used to covalently attach the peptide via its lysine groups in situ within the cross-flow reaction chamber onto this membrane (Herfurth, E., Pilling, U. & Wittmann-Liebold, B. (1990) J. Prot. Chem. 9, 267). We found these membranes very suitable for peptide degradations in the Knauer sequencer. In almost all cases we were able to identify the amino-acid residues of the peptide up to its last covalent fixation point to the membrane.

  2. Helicobacter pylori cholesteryl glucosides interfere with host membrane phase and affect type IV secretion system function during infection in AGS cells.

    Science.gov (United States)

    Wang, Hung-Jung; Cheng, Wen-Chi; Cheng, Hsin-Hung; Lai, Chih-Ho; Wang, Wen-Ching

    2012-01-01

    Helicobacter pylori infection is an aetiological cause of gastric disorders worldwide. H. pylori has been shown to assimilate and convert host cholesterol into cholesteryl glucosides (CGs) by cholesterol-α-glucosyltransferase encoded by capJ. Here, we show that CapJ-deficient (ΔcapJ) H. pylori resulted in greatly reduced type IV secretion system (TFSS)-associated activities, including the hummingbird phenotype of AGS cells, IL-8 production, CagA translocation/phosphorylation and CagA-mediated signalling events. Complementation of the ΔcapJ mutation with wild type cagJ or by adding CGs-containing lysates or exogenous fluorophore-tagged CGs reversed the mutant phenotypes. We also show that the wild-type but not ΔcapJ H. pylori recruited raft-associated components to sites of bacterial attachment. Fluorescence recovery after photobleaching (FRAP) analysis of AGS cells treated with fluorescence-tagged cholesterol/CGs revealed that there was a higher proportion of CGs associated with immobile fractions. CGs-associated membranes were also more resistant to a cold detergent extraction. Thus, we propose that CGs synthesized by H. pylori around host-pathogen contact sites partition in detergent-resistant membranes (DRMs), alters lateral-phase segregation in membrane and reorganizes membrane architecture. These processes together promote the formation of a functional TFSS and H. pylori infection.

  3. Different phase behavior and packing of ceramides with long (C16) and very long (C24) acyls in model membranes: infrared spectroscopy using deuterated lipids.

    Science.gov (United States)

    Školová, Barbora; Hudská, Klára; Pullmannová, Petra; Kováčik, Andrej; Palát, Karel; Roh, Jaroslav; Fleddermann, Jana; Estrela-Lopis, Irina; Vávrová, Kateřina

    2014-09-04

    Ceramides (Cer) are the central molecules in sphingolipid metabolism that participate in cellular signaling and also prevent excessive water loss by the skin. Previous studies showed that sphingosine-based Cer with a long 16C chain (CerNS16) and very long 24C-chain ceramides (CerNS24) differ in their biological actions. Increased levels of long CerNS16 at the expense of the very long CerNS24 have been found in atopic dermatitis patients, and this change correlated with the skin barrier properties. To probe the membrane behavior of the long CerNS16 and the very long chain CerNS24, we studied their interactions with fatty acids and cholesterol in model stratum corneum membranes using infrared spectroscopy. Using Cer with deuterated acyls and/or deuterated fatty acids, we showed differences in lipid mixing, packing, and thermotropic phase behavior between long and very long Cer. These differences were observed in the presence of lignoceric acid or a heterogeneous fatty acid mixture (C16-C24), in the presence or absence of cholesterol sulfate, and at 5-95% humidity. In these membranes, very long CerNS24 prefers an extended (splayed-chain) conformation in which the fatty acid is associated with the very long Cer chain. In contrast, the shorter CerNS16 and fatty acids are mostly phase separated.

  4. LiFAP-based PVdF-HFP microporous membranes by phase-inversion technique with Li/LiFePO{sub 4} cell

    Energy Technology Data Exchange (ETDEWEB)

    Aravindan, V.; Vickraman, P. [Gandhigram Rural University, Department of Physics, Gandhigram (India); Sivashanmugam, A.; Thirunakaran, R.; Gopukumar, S. [Central Electrochemical Research Institute, Electrochemical Energy Systems Division, Karaikudi (India)

    2009-12-15

    Polyvinylidenefluoride-hexafluoropropylene-based (PVdF-HFP-based) gel and composite microporous membranes (GPMs and CPMs) were prepared by phase-inversion technique in the presence 10 wt% of AlO(OH){sub n} nanoparticles. The prepared membranes were gelled with 0.5-M LiPF{sub 3}(CF{sub 2}CF{sub 3}){sub 3} (lithium fluoroalkylphosphate, LiFAP) in EC:DEC (1:1 v/v) and subjected to various characterizations; the AC impedance study shows that CPMs exhibit higher conductivity than GPMs. Mechanical stability measurements on these systems reveal that CPMs exhibit Young's modulus higher than that of bare and GPMs and addition of nanoparticles drastically improves the elongation break was also noted. Transition of the host from {alpha} to {beta} phase after the loading of nanosized filler was confirmed by XRD and Raman studies. Physico-chemical properties, like liquid uptake, porosity, surface area, and activation energy, of the membranes were calculated and results are summarized. Cycling performance of Li/CPM/LiFePO{sub 4} coin cell was fabricated and evaluated at C/10 rate and delivered a discharge capacity of 157 and 148 mAh g {sup -1} respectively for first and tenth cycles. (orig.)

  5. LiFAP-based PVdF-HFP microporous membranes by phase-inversion technique with Li/LiFePO4 cell

    Science.gov (United States)

    Aravindan, V.; Vickraman, P.; Sivashanmugam, A.; Thirunakaran, R.; Gopukumar, S.

    2009-12-01

    Polyvinylidenefluoride-hexafluoropropylene-based (PVdF-HFP-based) gel and composite microporous membranes (GPMs and CPMs) were prepared by phase-inversion technique in the presence 10 wt% of AlO(OH) n nanoparticles. The prepared membranes were gelled with 0.5-M LiPF3(CF2CF3)3 (lithium fluoroalkylphosphate, LiFAP) in EC:DEC (1:1 v/v) and subjected to various characterizations; the AC impedance study shows that CPMs exhibit higher conductivity than GPMs. Mechanical stability measurements on these systems reveal that CPMs exhibit Young’s modulus higher than that of bare and GPMs and addition of nanoparticles drastically improves the elongation break was also noted. Transition of the host from α to β phase after the loading of nanosized filler was confirmed by XRD and Raman studies. Physico-chemical properties, like liquid uptake, porosity, surface area, and activation energy, of the membranes were calculated and results are summarized. Cycling performance of Li/CPM/LiFePO4 coin cell was fabricated and evaluated at C/10 rate and delivered a discharge capacity of 157 and 148 mAh g-1 respectively for first and tenth cycles.

  6. Ionic liquid-impregnated agarose film two-phase micro-electrodriven membrane extraction (IL-AF-μ-EME) for the analysis of antidepressants in water samples.

    Science.gov (United States)

    Mohamad Hanapi, Nor Suhaila; Sanagi, Mohd Marsin; Ismail, Abd Khamim; Wan Ibrahim, Wan Aini; Saim, Nor'ashikin; Wan Ibrahim, Wan Nazihah

    2017-03-01

    The aim of this study was to investigate and apply supported ionic liquid membrane (SILM) in two-phase micro-electrodriven membrane extraction combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV) for pre-concentration and determination of three selected antidepressant drugs in water samples. A thin agarose film impregnated with 1-hexyl-3-methylimidazolium hexafluorophosphate, [C6MIM] [PF6], was prepared and used as supported ionic liquid membrane between aqueous sample solution and acceptor phase for extraction of imipramine, amitriptyline and chlorpromazine. Under the optimized extraction conditions, the method provided good linearity in the range of 1.0-1000μgL(-1), good coefficients of determination (r(2)=0.9974-0.9992) and low limits of detection (0.1-0.4μgL(-1)). The method showed high enrichment factors in the range of 110-150 and high relative recoveries in the range of 88.2-111.4% and 90.9-107.0%, for river water and tap water samples, respectively with RSDs of ≤7.6 (n=3). This method was successfully applied to the determination of the drugs in river and tap water samples. It is envisaged that the SILM improved the perm-selectivity by providing a pathway for targeted analytes which resulted in rapid extraction with high degree of selectivity and high enrichment factor.

  7. The Role of Oxygen Partial Pressure in Controlling the Phase Composition of La1- x Sr x Co y Fe1- y O3- δ Oxygen Transport Membranes Manufactured by Means of Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Marcano, D.; Mauer, G.; Sohn, Y. J.; Vaßen, R.; Garcia-Fayos, J.; Serra, J. M.

    2016-04-01

    La0.58Sr0.4Co0.2Fe0.8O3 - δ (LSCF) deposited on a metallic porous support by plasma spray-physical vapor deposition is a promising candidate for oxygen-permeation membranes. Ionic transport properties are regarded to depend on the fraction of perovskite phase present in the membrane. However, during processing, the LSCF powder decomposes into perovskite and secondary phases. In order to improve the ionic transport properties of the membranes, spraying was carried out at different oxygen partial pressures p(O2). It was found that coatings deposited at lower and higher oxygen partial pressures consist of 70% cubic/26% rhombohedral and 61% cubic/35% rhombohedral perovskite phases, respectively. During annealing, the formation of non-perovskite phases is driven by oxygen non-stoichiometry. The amount of oxygen added during spraying can be used to increase the perovskite phase fraction and suppress the formation of non-perovskite phases.

  8. Constructing dense genetic linkage maps

    NARCIS (Netherlands)

    Jansen, J.; Jong, de A.G.; Ooijen, van J.W.

    2001-01-01

    This paper describes a novel combination of techniques for the construction of dense genetic linkage maps. The construction of such maps is hampered by the occurrence of even small proportions of typing errors. Simulated annealing is used to obtain the best map according to the optimality criterion:

  9. Method for dense packing discovery.

    Science.gov (United States)

    Kallus, Yoav; Elser, Veit; Gravel, Simon

    2010-11-01

    The problem of packing a system of particles as densely as possible is foundational in the field of discrete geometry and is a powerful model in the material and biological sciences. As packing problems retreat from the reach of solution by analytic constructions, the importance of an efficient numerical method for conducting de novo (from-scratch) searches for dense packings becomes crucial. In this paper, we use the divide and concur framework to develop a general search method for the solution of periodic constraint problems, and we apply it to the discovery of dense periodic packings. An important feature of the method is the integration of the unit-cell parameters with the other packing variables in the definition of the configuration space. The method we present led to previously reported improvements in the densest-known tetrahedron packing. Here, we use the method to reproduce the densest-known lattice sphere packings and the best-known lattice kissing arrangements in up to 14 and 11 dimensions, respectively, providing numerical evidence for their optimality. For nonspherical particles, we report a dense packing of regular four-dimensional simplices with density ϕ=128/219≈0.5845 and with a similar structure to the densest-known tetrahedron packing.

  10. Unconditional Continuous Variable Dense Coding

    CERN Document Server

    Ralph, T C

    2002-01-01

    We investigate the conditions under which unconditional dense coding can be achieved using continuous variable entanglement. We consider the effect of entanglement impurity and detector efficiency and discuss experimental verification. We conclude that the requirements for a strong demonstration are not as stringent as previously thought and are within the reach of present technology.

  11. 超高压联合高密度 CO2处理钝化对虾多酚氧化酶%Inactivation of polyphenol oxidase from Litopenaeus vannamei treated by ultra high pressure combined dense phase carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    邓倩琳; 刘书成; 刘蒙娜; 刘媛; 郭明慧; 吉宏武; 李承勇; 高静

    2016-01-01

    Ultra high pressure (UHP) and dense phase carbon dioxide (DPCD) processes are effective non-thermal pasteurization methods that have gained increasing attention in inactivation of undesired enzymes and microorganisms in food industry. The advantage of UHP is to process foods that are already packaged and therefore are not liable to post-process contamination. Although UHP effectively eliminates microorganisms, it does not inactivate some key enzymes that reduce the product quality. For example, UHP may increase the activities of polyphenol oxidase (PPO) at lower pressure. As a continuous operation, DPCD needs aseptic filling to containers, but can inactivate enzymes. Therefore it is logical to combine these technologies to benefit from their individual advantages. The presence of carbon dioxide (CO2) in the sample medium might create a more acidic environment and synergistically interact with pressure to damage or alter the structures of enzymes and microbial cells. In order to make up for the disadvantage of UHP in inactivating PPO and use the advantage of DPCD in inactivating PPO, the inactivation effect of PPO from Litopenaeus vannamei treated by UHP combined with CO2 (UHP+CO2) was studied, and the feasibility of developing new shrimp products by UHP+CO2 was explored. The crude PPO extracts of 2 mL were treated with 2% CO2 (v/v) package alone, or UHP alone, or UHP + 2% CO2 (v/v). The treatment temperature was 30±2 ℃. The treatment pressure was 100, 200, 300, 400 and 500 MPa, respectively. The treatment time was 5, 10, 15, 20, 25 and 30 min, respectively. The results showed that: The PPO was inactivated more effectively by UHP+CO2 than CO2 treatment and UHP treatment alone. Treated at 100 MPa for 30 min by UHP+CO2, PPO activity dropped to 18.92%±1.52%. At 200 MPa for 10 min by UHP+CO2, PPO activity dropped to 10.91%±1.08%. At 300 MPa for 10 min by UHP+CO2, 95% PPO was inactivated. At 400 MPa for 5 min by UHP+CO2, the residual activity of PPO was less than 3

  12. Effect of Sintering Temperature on Microstructure and Hydrogen Permeation Properties of Perovskite Membrane

    Institute of Scientific and Technical Information of China (English)

    Marzieh Heidari; Akbar Zamaniyan; Aliakbar SafeKordi; Ensieh Ganji Babakhani; Mahdi Amanipour

    2013-01-01

    The BaCe0.9Y0.1O3-δ (BCY) perovskite membrane was successfully synthesized by liquid citrate method.The phase structure of the powder was characterized by X-ray diffraction (XRD).Scanning electron microscopy (SEM) was used to characterize microstructures of the membrane sintered under various conditions.Sintering temperatures and dwell time during sintering influence the final microstructure of the ceramic.Results showed that increasing sintering temperature resulted in a dense membrane with clear grains.An increase of dwell time was favorable to produce membranes with larger grains in the sintered ceramics.A density of 5.87 g/cm3 was reached for the membrane after sintering at 1200 C with dwell time of 10 h.This resulted in the formation of dense membranes with clear structure and average grain size of 0.27 μm.The influence of microstructure on the hydrogen permeation flux through BCY was observed by measuring the hydrogen permeation flux,and the results showed that hydrogen permeation flux increases with increasing the average grain size of the membrane.From H2 permeation rates,it was found that bulk diffusion rather than surface reaction played the dominant role in H2 transport.

  13. Charge-discharge studies on a lithium cell composed of PVdF-HFP polymer membranes prepared by phase inversion technique with a nanocomposite cathode

    Science.gov (United States)

    Manuel Stephan, A.; Teeters, Dale

    A novel polymer membrane of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by the phase inversion technique with two different non-solvents, 1-butanol or hexane. The prepared films were analyzed by scanning electron microscope (SEM) and nitrogen absorption/desorption techniques. The change in the morphology and pore diameter of the films prepared with different non-solvents correlates with the structure of the non-solvents used. This electrolyte membrane was coupled with a nanocomposite LiAl 0.01Co 0.99O 2 cathode which was prepared by a solid-state reaction method and subsequently by ball-milling. Lithium cells consisting of LiAl 0.01Co 0.99O 2/polymer electrolyte/Li were assembled and their charge-discharge studies were investigated.

  14. Liquid-phase membrane extraction of targeted pesticides from manufacturing wastewaters in a hollow fibre contactor with feed-stream recycle.

    Science.gov (United States)

    Đorđević, Jelena; Vladisavljević, Goran T; Trtić-Petrović, Tatjana

    2017-01-01

    A two-phase membrane extraction in a hollow fibre contactor with feed-stream recycle was applied to remove selected pesticides (tebufenozide, linuron, imidacloprid, acetamiprid and dimethoate) from their mixed aqueous solutions. The contactor consisted of 50 polypropylene hollow fibres impregnated with 5% tri-n-octylphosphine oxide in di-n-hexyl ether. For low-polar pesticides with log P ≥ 2 (tebufenozide and linuron), the maximum removal efficiency increased linearly from 85% to 96% with increasing the feed flow rate. The maximum removal efficiencies of more polar pesticides were significantly higher under feed recirculation (86%) than in a continuous single-pass operation (30%). It was found from the Wilson's plot that the mass transfer resistance of the liquid membrane can be neglected for low-polar pesticides. The pesticide removals from commercial formulations were similar to those from pure pesticide solutions, indicating that built-in adjuvants did not affect the extraction process.

  15. Solid phase extraction of zinc(II) using a PVC-based polymer inclusion membrane with di(2-ethylhexyl)phosphoric acid (D2EHPA) as the carrier.

    Science.gov (United States)

    Kolev, Spas D; Baba, Yoshinari; Cattrall, Robert W; Tasaki, Tsutomu; Pereira, Natalie; Perera, Jilska M; Stevens, Geoffrey W

    2009-05-15

    A polymer inclusion membrane (PIM) is reported consisting of 45% (m/m) di(2-ethylhexyl)phosphoric acid (D2EHPA) immobilized in poly(vinyl chloride) (PVC) for use as a solid phase absorbent for selectively extracting Zn(II) from aqueous solutions in the presence of Cd(II), Co(II), Cu(II), Ni(II) and Fe(II). Interference from Fe(III) in the sample is eliminated by precipitation with orthophosphate prior to the extraction of Zn(II). Studies using a dual compartment transport cell have shown that the Zn(II) flux (2.58 x 10(-6)mol m(-2)s(-1)) is comparable to that observed for supported liquid membranes. The stoichiometry of the extracted complex is shown to be ZnR(2).HR, where R is the D2EHPA anion.

  16. Peptide mapping of /sup 125/I-labelled membrane protein of influenza viruses by reverse-phase high-performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Darveau, A.; Lecomte, J. (Centre de Recherche en Virologie, Institut Armand-Frappier, Laval, Quebec (Canada)); Seidah, N.G.; Chretien, M. (Institut de Recherches Cliniques de Montreal, Montreal (Canada))

    1982-03-01

    The resolution potential of reverse-phase high-performance liquid chromatography (HPLC) for peptide analysis of hydrophobic viral membranes has been investigated, using as a model the membrane (M) protein of influenza virus. Proteolytic digests of /sup 125/I-labelled M protein CNBr fragments, extracted from radioiodinated whole virus, have been separated on a uBondapak C/sub 18/ column with an isopropanol or acetonitrile solvent system. Peptide mapping of trypsin digests of M protein from A/PR/8/34 (H1N1) and A/chicken/Germany/N/49 (H10N7) viruses was identical, whereas Staphylococcus aureus V8 protease digests showed minor differences in at least two peptides. The results also show that HPLC is a powerful tool for the separation of proteolytic digests of viral proteins, since the peptide maps are highly reproducible and recovery was always greater than 85%.

  17. Cholesterol rules: direct observation of the coexistence of two fluid phases in native pulmonary surfactant membranes at physiological temperatures

    DEFF Research Database (Denmark)

    Bernardino de la Serna, Jorge; Perez-Gil, Jesus; Simonsen, Adam C

    2004-01-01

    Pulmonary surfactant, the lipid-protein material that stabilizes the respiratory surface of the lungs, contains approximately equimolar amounts of saturated and unsaturated phospholipid species and significant proportions of cholesterol. Such lipid composition suggests that the membranes taking...... part in the surfactant structures could be organized heterogeneously in the form of inplane domains, originating from particular distributions of specific proteins and lipids. Here we report novel results concerning the lateral organization of bilayer membranes made of native pulmonary surfactant where...... of this material is naturally designed to be at the "edge" of a lateral structure transition under physiological conditions, likely providing particular structural and dynamic properties for its mechanical function. The observed lateral structure in native pulmonary surfactant membranes is dramatically affected...

  18. From biological membranes to biomimetic model membranes

    Directory of Open Access Journals (Sweden)

    Eeman, M.

    2010-01-01

    Full Text Available Biological membranes play an essential role in the cellular protection as well as in the control and the transport of nutrients. Many mechanisms such as molecular recognition, enzymatic catalysis, cellular adhesion and membrane fusion take place into the biological membranes. In 1972, Singer et al. provided a membrane model, called fluid mosaic model, in which each leaflet of the bilayer is formed by a homogeneous environment of lipids in a fluid state including globular assembling of proteins and glycoproteins. Since its conception in 1972, many developments were brought to this model in terms of composition and molecular organization. The main development of the fluid mosaic model was made by Simons et al. (1997 and Brown et al. (1997 who suggested that membrane lipids are organized into lateral microdomains (or lipid rafts with a specific composition and a molecular dynamic that are different to the composition and the dynamic of the surrounding liquid crystalline phase. The discovery of a phase separation in the plane of the membrane has induced an explosion in the research efforts related to the biology of cell membranes but also in the development of new technologies for the study of these biological systems. Due to the high complexity of biological membranes and in order to investigate the biological processes that occur on the membrane surface or within the membrane lipid bilayer, a large number of studies are performed using biomimicking model membranes. This paper aims at revisiting the fundamental properties of biological membranes in terms of membrane composition, membrane dynamic and molecular organization, as well as at describing the most common biomimicking models that are frequently used for investigating biological processes such as membrane fusion, membrane trafficking, pore formation as well as membrane interactions at a molecular level.

  19. Integrated method of thermosensitive triblock copolymer-salt aqueous two phase extraction and dialysis membrane separation for purification of lycium barbarum polysaccharide.

    Science.gov (United States)

    Wang, Yun; Hu, Xiaowei; Han, Juan; Ni, Liang; Tang, Xu; Hu, Yutao; Chen, Tong

    2016-03-01

    A polymer-salt aqueous two-phase system (ATPS) consisting of thermosensitive copolymer ethylene-oxide-b-propylene-oxide-b-ethylene-oxide (EOPOEO) and NaH2PO4 was employed in deproteinization for lycium barbarum polysaccharide (LBP). The effects of salt type and concentration, EOPOEO concentration, amount of crude LBP solution and temperature were studied. In the primary extraction process, LBP was preferentially partitioned to the bottom (salt-rich) phase with high recovery ratio of 96.3%, while 94.4% of impurity protein was removed to the top (EOPOEO-rich) phase. Moreover, the majority of pigments could be discarded to top phase. After phase-separation, the LBP in the bottom phase was further purified by dialysis membrane to remove salt and other small molecular impurities. The purity of LBP was enhanced to 64%. Additionally, the FT-IR spectrum was used to identify LBP. EOPOEO was recovered by a temperature-induced separation, and reused in a new ATPS. An ideal extraction and recycle result were achieved.

  20. Rapid haplotype reconstruction in predigrees with dense marker maps

    NARCIS (Netherlands)

    Windig, J.J.; Meuwissen, T.H.E.

    2004-01-01

    Reconstruction of marker phases is not straightforward when parents are untyped. In these cases information from other relatives has to be used. In dense marker maps, however, the space of possible haplotype configurations tends to be too large for procedures such as Monte Carlo Markov chains (MCMC)

  1. Menthol-induced action potentials in Conocephalum conicum as a result of unspecific interactions between menthol and the lipid phase of the plasma membrane.

    Science.gov (United States)

    Kupisz, Kamila; Trebacz, Kazimierz; Gruszecki, Wiesław I

    2015-07-01

    Our previous study has shown that the liverwort Conocephalum conicum generates action potentials (APs) in response to both temperature drop and menthol, which are also activators of the TRPM8 (transient receptor potential melastatin 8) receptor in animals. Not only similarities but also differences between electrical reactions to menthol and cooling observed in the liverwort aroused our interest in the action of menthol at the molecular level. Patch-clamp investigations have shown that menthol causes a reduction of current flowing through slow vacuolar (SV) channels to 29 ± 10% of the initial value (n = 9); simultaneously, it does not influence magnitudes of currents passing through a single SV channel. This may point to an unspecific interaction between menthol and the lipid phase of the membrane. An influence of menthol on lipid organization in membranes was investigated in two-component monomolecular layers formed with menthol and dipalmitoylphosphatidylcholine (DPPC) at the argon-water interface. Analyses of the mean molecular area parameters vs the molar fraction of the menthol component have shown over-additivity (approximately 20 Å(2) ) in the region of high molar fractions of menthol. Infrared absorption spectroscopy studies have shown that menthol, most probably, induces breaking of a hydrogen bond network formed by ester carbonyl groups and water bridges in the lipid membrane and binds to the polar head group region of DPPC. We conclude that the disruption in the lipid phase of the membrane influences ion channels and/or pumps and subsequently causes generation of APs in excitable plants such as C. conicum.

  2. Arginine in α-defensins: differential effects on bactericidal activity correspond to geometry of membrane curvature generation and peptide-lipid phase behavior.

    Science.gov (United States)

    Schmidt, Nathan W; Tai, Kenneth P; Kamdar, Karishma; Mishra, Abhijit; Lai, Ghee Hwee; Zhao, Kun; Ouellette, André J; Wong, Gerard C L

    2012-06-22

    The conserved tridisulfide array of the α-defensin family imposes a common triple-stranded β-sheet topology on peptides that may have highly diverse primary structures, resulting in differential outcomes after targeted mutagenesis. In mouse cryptdin-4 (Crp4) and rhesus myeloid α-defensin-4 (RMAD4), complete substitutions of Arg with Lys affect bactericidal peptide activity very differently. Lys-for-Arg mutagenesis attenuates Crp4, but RMAD4 activity remains mostly unchanged. Here, we show that the differential biological effect of Lys-for-Arg replacements can be understood by the distinct phase behavior of the experimental peptide-lipid system. In Crp4, small-angle x-ray scattering analyses showed that Arg-to-Lys replacements shifted the induced nanoporous phases to a different range of lipid compositions compared with the Arg-rich native peptide, consistent with the attenuation of bactericidal activity by Lys-for-Arg mutations. In contrast, such phases generated by RMAD4 were largely unchanged. The concordance between small-angle x-ray scattering measurements and biological activity provides evidence that specific types of α-defensin-induced membrane curvature-generating tendencies correspond directly to bactericidal activity via membrane destabilization.

  3. Role of microorganism growth phase in the accumulation and characteristics of biomacromolecules (BMM) in a membrane bioreactor

    DEFF Research Database (Denmark)

    Zhou, Zhongbo; Meng, Fangang; Liang, Shuang

    2012-01-01

    The objective of this study was to highlight the significance of microorganism growth on the production of biomacromolecules (BMM) in a membrane bioreactor (MBR). During the MBR operation, both polysaccharides and proteins in the sludge supernatant were found to increase steadily in exponential...

  4. Acquisition of desiccation tolerance in developing wheat embryos correlates with appearance of a fluid phase in membranes

    NARCIS (Netherlands)

    Golovina, E.A.; Hoekstra, F.A.

    2003-01-01

    Membrane behaviour in developing wheat (Triticum aestivum cv Priokskaya) embryos was studied in relation to the acquisition of desiccation tolerance, using spin probe techniques. Fresh embryos were able to develop into seedlings at day 15 after anthesis, but it took 18 d before fast-dried, isolated

  5. Acquisition of desiccation tolerance in developing wheat embryos correlates with appearance of a fluid phase in membranes

    NARCIS (Netherlands)

    Golovina, E.A.; Hoekstra, F.A.

    2003-01-01

    Membrane behaviour in developing wheat (Triticum aestivum cv Priokskaya) embryos was studied in relation to the acquisition of desiccation tolerance, using spin probe techniques. Fresh embryos were able to develop into seedlings at day 15 after anthesis, but it took 18 d before fast-dried, isolated

  6. STED microscopy detects and quantifies liquid phase separation in lipid membranes using a new far-red emitting fluorescent phosphoglycerolipid analogue.

    Science.gov (United States)

    Honigmann, Alf; Mueller, Veronika; Hell, Stefan W; Eggeling, Christian

    2013-01-01

    We have developed a bright, photostable, and far-red emitting fluorescent phosphoglycerolipid analogue to probe diffusion characteristics of lipids in membranes. The lipid analogue consists of a saturated (C18) phosphoethanolamine and a hydrophilic far-red emitting fluorescent dye (KK114) that is tethered to the head group by a long polyethylenglycol linker. In contrast to reported far-red emitting fluorescent lipid analogues, this one partitions predominantly into liquid ordered domains of phase-separated ternary bilayers. We performed fluorescence correlation spectroscopy with a super-resolution STED microscope (STED-FCS) to measure the lateral diffusion of the new lipid analogue in the liquid ordered (Lo) and disordered (Ld) phase. On a mica support, we observed micrometer large phases and found that the lipid analogue diffuses freely on all tested spatial scales (40-250 nm) in both the Ld and Lo phase with diffusion coefficients of 1.8 microm2 s(-1) and 0.7 microm2 s(-1) respectively. This indicates that the tight molecular packing of the Lo phase mainly slows down the diffusion rather than causing anomalous sub-diffusion. The same ternary mixture deposited on acid-cleaned glass forms Lo nanodomains of analogue into the nano-domains, where diffusion is slowed down. Our results suggest that STED-FCS in combination with a Lo-partitioning fluorescent lipid analogue can directly probe the presence of Lo nano-domains, which in the future should allow the study of potential lipid rafts in live-cell membranes.

  7. Highly permeable double-skinned forward osmosis membranes for anti-fouling in the emulsified oil-water separation process

    KAUST Repository

    Duong, Hoang Hanh Phuoc

    2014-04-15

    Forward osmosis (FO) has attracted wide attention in recent years. However, the FO performance may be restricted due to internal concentration polarization (ICP) and fast fouling propensity that occurs in the membrane sublayer. Particularly, these problems significantly affect the membrane performance when treating highly contaminated oily wastewater. Recently, double-skinned flat sheet cellulose acetate (CA) membranes consisting of two selective skins via the phase inversion method have demonstrated less ICP and fouling propensity over typical single-skinned membranes. However, these membranes exhibit low water fluxes of <12 LMH under 2 M NaCl draw solution. Therefore, a novel double-skinned FO membrane with a high water flux has been aimed for in this study for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between (i) a truly dense skin for salt rejection and (ii) a fairly loose dense skin for emulsified oil particle rejection. The former dense skin is a polyamide synthesized via interfacial polymerization, while the latter one is a self-assembled sulfonated pentablock copolymer (Nexar copolymer) layer. The resultant double-skinned membrane exhibits a high water flux of 17.2 LMH and a low reverse salt transport of 4.85 gMH using 0.5 M NaCl as the draw solution and DI water as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation. © 2014 American Chemical Society.

  8. Solids flow rate measurement in dense slurries

    Energy Technology Data Exchange (ETDEWEB)

    Porges, K.G.; Doss, E.D.

    1993-09-01

    Accurate and rapid flow rate measurement of solids in dense slurries remains an unsolved technical problem, with important industrial applications in chemical processing plants and long-distance solids conveyance. In a hostile two-phase medium, such a measurement calls for two independent parameter determinations, both by non-intrusive means. Typically, dense slurries tend to flow in laminar, non-Newtonian mode, eliminating most conventional means that usually rely on calibration (which becomes more difficult and costly for high pressure and temperature media). These issues are reviewed, and specific solutions are recommended in this report. Detailed calculations that lead to improved measuring device designs are presented for both bulk density and average velocity measurements. Cross-correlation, chosen here for the latter task, has long been too inaccurate for practical applications. The cause and the cure of this deficiency are discussed using theory-supported modeling. Fluid Mechanics are used to develop the velocity profiles of laminar non-Newtonian flow in a rectangular duct. This geometry uniquely allows the design of highly accurate `capacitive` devices and also lends itself to gamma transmission densitometry on an absolute basis. An absolute readout, though of less accuracy, is also available from a capacitive densitometer and a pair of capacitive sensors yields signals suitable for cross-correlation velocity measurement.

  9. Holographic Renormalization in Dense Medium

    Directory of Open Access Journals (Sweden)

    Chanyong Park

    2014-01-01

    describes a dense medium at finite temperature, is investigated in this paper. In a dense medium, two different thermodynamic descriptions are possible due to an additional conserved charge. These two different thermodynamic ensembles are classified by the asymptotic boundary condition of the bulk gauge field. It is also shown that in the holographic renormalization regularity of all bulk fields can reproduce consistent thermodynamic quantities and that the Bekenstein-Hawking entropy is nothing but the renormalized thermal entropy of the dual field theory. Furthermore, we find that the Reissner-Nordström AdS black brane is dual to a theory with conformal matter as expected, whereas a charged black brane with a nontrivial dilaton profile is mapped to a theory with nonconformal matter although its leading asymptotic geometry still remains as AdS space.

  10. Radiative properties of dense nanofluids.

    Science.gov (United States)

    Wei, Wei; Fedorov, Andrei G; Luo, Zhongyang; Ni, Mingjiang

    2012-09-01

    The radiative properties of dense nanofluids are investigated. For nanofluids, scattering and absorbing of electromagnetic waves by nanoparticles, as well as light absorption by the matrix/fluid in which the nanoparticles are suspended, should be considered. We compare five models for predicting apparent radiative properties of nanoparticulate media and evaluate their applicability. Using spectral absorption and scattering coefficients predicted by different models, we compute the apparent transmittance of a nanofluid layer, including multiple reflecting interfaces bounding the layer, and compare the model predictions with experimental results from the literature. Finally, we propose a new method to calculate the spectral radiative properties of dense nanofluids that shows quantitatively good agreement with the experimental results.

  11. Dilatons for Dense Hadronic Matter

    CERN Document Server

    Lee, Hyun Kyu

    2009-01-01

    The idea that the explicit breaking of scale invariance by the trace anomaly of QCD can be rephrased as a spontaneous breaking has been recently exploited to capture the low-energy strong interaction dynamics of dense (and also hot) matter in terms of two dilaton fields, the "soft" (chi_s) and the "hard" (chi_h) fields, in the frame work of the hidden local gauge symmetry. In the Freund-Nambu model, the spontaneous symmetry breaking of scale symmetry is induced by an explicitly breaking term, while the spontaneous symmetry breaking is possible in the flat potential model which is scale symmetric. We discuss the interplay of the soft and hard dilatons using the spontaneously broken scale symmetry schemes and uncover a novel structure of dense matter hitherto unexplored.

  12. Performance and Characterization for Blend Membrane of PES with Manganese(III Acetylacetonate as Metalorganic Nanoparticles

    Directory of Open Access Journals (Sweden)

    H. Abdallah

    2015-01-01

    Full Text Available This study describes the preparation, characterization, and evaluation of performance of blend Polyethersulfone (PES with manganese(III acetylacetonate Mn(acac3 to produce reverse osmosis blend membrane. The manganese(III acetylacetonate nanoparticles were prepared by a simple and environmentally benign route based on hydrolysis of KMnO4 followed by reaction with acetylacetone in rapid stirring rate. The prepared nanoparticle powder was dissolved in polymer solution mixture to produce RO PES/Mn(acac3 blend membrane, without any treatment of Polyethersulfone membrane surface. The membrane morphology, mechanical properties, and performance were presented. The scanning electron microscopy (SEM images have displayed a typical asymmetric membrane structure with a dense top layer due to the migration of Mn(acac3 nanoparticles to membrane surface during the phase inversion process. Contact angle measurements have indicated that the hydrophilicity of the membrane was improved by adding Mn(acac3. AFM images have proved excellent pores size distribution of blend membrane and lower surface roughness compared with bare PES. The desalination test was applied to blend membrane, where the blend membrane provided good performance; particularly, permeate flux was 24.2 Kg/m2·h and salt rejection was 99.5%.

  13. Effect of polyethyleneglycol on CH{sub 4} permeation through poly(amide-b-ethylene oxide)-based nanocomposite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Asghari, Morteza, E-mail: asghari@kashanu.ac.ir [Separation Processes Research Group (SPRG), University of Kashan, Kashan (Iran, Islamic Republic of); Energy Research Institute, University of Kashan, Ghotb-e-Ravandi Avenue, Kashan (Iran, Islamic Republic of); Mahmudi, Amir; Zargar, Vida [Separation Processes Research Group (SPRG), University of Kashan, Kashan (Iran, Islamic Republic of); Khanbabaei, Ghader [Polymer Science and Technology Division, Research Institute of Petroleum Industry, Tehran (Iran, Islamic Republic of)

    2014-11-01

    Graphical abstract: - Highlights: • A three-phase polymer/liquid/solid (PEBA/PEG/zeolite X) membrane was fabricated. • Nanocrystalline zeolite X was used as filler to stabilize membrane polymeric matrix. • Introducing zeolite to PEBA matrix caused its total free volume to decrease. • A gradual decrease with pressure was observed in CH{sub 4} permeability for the membranes. • In all the experiments, operating pressures varied from 2 to 8 bar. - Abstract: A three-phase polymer/liquid/solid poly(amide-b-ethylene oxide) (PEBA)/polyethylene glycol (PEG)/zeolite X was fabricated and its gas permeability was investigated. CH{sub 4} permeability of neat PEBA, two-phase PEBA/NaX and three-phase PEBA/PEG/NaX were compared for different pressures within the range of 2–8 bar. The fabricated membranes were structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscope (AFM). SEM images showed that the zeolite grain size was homogeneously smaller than 2 μm. They also revealed the dense structures of the membranes and no pores were observed at these magnifications. AFM surface images indicated that the membranes surface roughness increased significantly with increasing zeolite loading. CH{sub 4} permeability for single-, two- and three-phase membranes decreased from 3.13 to 2.81, from 3.96 to 2.31 and from 2.67 to 2.14 barrer, respectively.

  14. Composite oxygen transport membrane

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Composite oxygen transport membrane

    Science.gov (United States)

    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.

  16. Evolution of Binaries in Dense Stellar Systems

    CERN Document Server

    Ivanova, Natalia

    2011-01-01

    In contrast to the field, the binaries in dense stellar systems are frequently not primordial, and could be either dynamically formed or significantly altered from their primordial states. Destruction and formation of binaries occur in parallel all the time. The destruction, which constantly removes soft binaries from a binary pool, works as an energy sink and could be a reason for cluster entering the binary-burning phase. The true binary fraction is greater than observed, as a result, the observable binary fraction evolves differently from the predictions. Combined measurements of binary fractions in globular clusters suggest that most of the clusters are still core-contracting. The formation, on other hand, affects most the more evolutionary advanced stars, which significantly enhances the population of X-ray sources in globular clusters. The formation of binaries with a compact objects proceeds mainly through physical collisions, binary-binary and single-binary encounters; however, it is the dynamical for...

  17. Carbon nitride frameworks and dense crystalline polymorphs

    Science.gov (United States)

    Pickard, Chris J.; Salamat, Ashkan; Bojdys, Michael J.; Needs, Richard J.; McMillan, Paul F.

    2016-09-01

    We used ab initio random structure searching (AIRSS) to investigate polymorphism in C3N4 carbon nitride as a function of pressure. Our calculations reveal new framework structures, including a particularly stable chiral polymorph of space group P 43212 containing mixed s p2 and s p3 bonding, that we have produced experimentally and recovered to ambient conditions. As pressure is increased a sequence of structures with fully s p3 -bonded C atoms and three-fold-coordinated N atoms is predicted, culminating in a dense P n m a phase above 250 GPa. Beyond 650 GPa we find that C3N4 becomes unstable to decomposition into diamond and pyrite-structured CN2.

  18. Plasmon resonance in warm dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Thiele, R; Bornath, T; Fortmann, C; Holl, A; Redmer, R; Reinholz, H; Ropke, G; Wierling, A; Glenzer, S H; Gregori, G

    2008-02-21

    Collective Thomson scattering with extreme ultraviolet light or x-rays is shown to allow for a robust measurement of the free electron density in dense plasmas. Collective excitations like plasmons appear as maxima in the scattering signal. Their frequency position can directly be related to the free electron density. The range of applicability of the standard Gross-Bohm dispersion relation and of an improved dispersion relation in comparison to calculations based on the dielectric function in random phase approximation is investigated. More important, this well-established treatment of Thomson scattering on free electrons is generalized in the Born-Mermin approximation by including collisions. We show that, in the transition region from collective to non-collective scattering, the consideration of collisions is important.

  19. Localization of methyl-branched ceramide [EOS] species within the long-periodicity phase in stratum corneum lipid model membranes: A neutron diffraction study.

    Science.gov (United States)

    Eichner, Adina; Sonnenberger, Stefan; Dobner, Bodo; Hauß, Thomas; Schroeter, Annett; Neubert, Reinhard H H

    2016-11-01

    The outermost layer of the mammalian skin, the stratum corneum (SC), is a very thin structure and realizes simultaneously the main barrier properties. The penetration barrier for xenobiotica is mostly represented by a complex lipid matrix. There is great interest in the subject of getting information about the arrangement of the lipids, which are mainly ceramides (CER), free fatty acids (FFA) and cholesterol (CHOL). SC lipid model membranes containing synthetically derived lipids in a non-physiological ratio were investigated. To compare the study to a former experiment, a methyl-branched ceramide [EOS] species in presence of the ultra-long chain CER[AP], CHOL and behenic acid (23/10/33/33, wt%) was applied. The membrane structure was studied using the very versatile technique of neutron diffraction. We were able to identify a long-periodicity phase (LPP) with a size of 114Å or 118Å with CER[EOS]-br in a ratio of >60wt% of the ceramides. Furthermore, we figured out two additional coexisting short-periodicity phases (SPP) with repeat distances of 48Å and 45Å, respectively. Partial deuterations of CER[EOS]-br and CER[AP] enabled the localization of the molecules within the multiphase system. CER[EOS]-d3 was present in the LPP, but absent in both SPP. CER[AP]-d3 was determined in both short phases but not localized within the LPP. Besides, we revealed influences of humidity and time with respect to the long-periodicity phase. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Probing warm dense lithium by inelastic X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Saiz, E.; Riley, D. [School of Mathematics and Physics, Queen' s University of Belfast, Belfast (United Kingdom); Gregori, G. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford (United Kingdom); Gregori, G.; Clarke, R.J.; Neely, D.; Notley, M.M.; Spindloe, C. [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX (United Kingdom); Gericke, D.O.; Vorberger, J.; Wunsch, K. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry (United Kingdom); Barbrel, B.; Koenig, M. [Laboratoire pour l' Utilisation des Laser Intenses, Ecole Polytechnique - Universite Paris-6, 91 - Palaiseau (France); Freeman, R.R.; Weber, R.L.; Van Woerkom, L. [Department of Physics, The Ohio State University, Columbus, Ohio (United States); Glenzer, S.H.; Landen, O.L.; Neumayer, P.; Price, D. [Lawrence Livermore National Laboratory, Livermore, California (United States); Khattak, F.Y. [Department of Physics, Kohat University of Science and Technology, Kohat-26000, NWFP (Pakistan); Pelka, A.; Roth, M.; Schollmeier, M. [Institut fur Kernphysik, Technische Universitat Darmstadt (Germany)

    2008-10-15

    One of the grand challenges of contemporary physics is understanding strongly interacting quantum systems comprising such diverse examples as ultracold atoms in traps, electrons in high-temperature superconductors and nuclear matter. Warm dense matter, defined by temperatures of a few electron volts and densities comparable with solids, is a complex state of such interacting matter. Moreover, the study of warm dense matter states has practical applications for controlled thermonuclear fusion, where it is encountered during the implosion phase, and it also represents laboratory analogues of astrophysical environments found in the core of planets and the crusts of old stars. Here we demonstrate how warm dense matter states can be diagnosed and structural properties can be obtained by inelastic X-ray scattering measurements on a compressed lithium sample. Combining experiments and ab initio simulations enables us to determine its microscopic state and to evaluate more approximate theoretical models for the ionic structure. (authors)

  1. DENSE: Displacement Encoding with Stimulated Echoes in Cardiac Functional MRI

    Science.gov (United States)

    Aletras, Anthony H.; Ding, Shujun; Balaban, Robert S.; Wen, Han

    1999-03-01

    Displacement encoding with stimulated echoes (DENSE) was developed for high-resolution myocardial displacement mapping. Pixel phase is modulated by myocardial displacement and data spatial resolution is limited only by pixel size. 2D displacement vector maps were generated for the systolic action in canines with 0.94 × 1.9 mm nominal in-plane resolution and 2.3 mm/π displacement encoding. A radial strain of 0.208 was measured across the free left ventricular wall over 105 ms during systole. DENSE displacement maps require small first-order gradient moments for encoding. DENSE magnitude images exhibit black-blood contrast which allows for better myocardial definition and reduced motion-related artifacts.

  2. Constructing Dense Graphs with Unique Hamiltonian Cycles

    Science.gov (United States)

    Lynch, Mark A. M.

    2012-01-01

    It is not difficult to construct dense graphs containing Hamiltonian cycles, but it is difficult to generate dense graphs that are guaranteed to contain a unique Hamiltonian cycle. This article presents an algorithm for generating arbitrarily large simple graphs containing "unique" Hamiltonian cycles. These graphs can be turned into dense graphs…

  3. The electron-atom interaction in partially ionized dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Omarbakiyeva, Yu A; Ramazanov, T S; Roepke, G [IETP, Al Farabi Kazakh National University, Tole Bi 96a, Almaty 050012 (Kazakhstan)], E-mail: yultuz@physics.kz

    2009-05-29

    The electron-atom interaction is considered in dense partially ionized plasmas. The separable potential is constructed from scattering data using effective radius theory. Parameters of the interaction potential were obtained from phase shifts, scattering length and effective radius. The binding energy of the electron in the H{sup -} ion is determined for the singlet channel on the basis of the reconstructed separable potential. In dense plasmas, the influence of the Pauli exclusion principle on the phase shifts and the binding energy is considered. Due to the Pauli blocking, the binding energy vanishes at the Mott density. At that density the behavior of the phase shifts is drastically changed. This leads to modifications of macroscopic properties such as composition and transport coefficients.

  4. 高密度CO2杀菌和钝酶及其在食品加工中应用的研究进展%Review on Inactivation of Microorganisms and Enzyme by Dense Phase Carbon Dioxide and the Application

    Institute of Scientific and Technical Information of China (English)

    刘书成; 郭明慧; 刘媛; 刘蒙娜; 邓倩琳

    2016-01-01

    总结近10年来国内外在高密度CO2(Dense phase carbon dioxide,DPCD)技术的基础研究和应用研究领域的相关工作。基础研究领域主要包括DPCD与食品体系的相平衡、DPCD杀灭微生物营养体和芽孢的效果与机制、DPCD钝酶的效果与机制等,应用研究领域主要包括DPCD在液体(果蔬汁、啤酒、牛奶)和固体食品(鲜切果蔬、肉制品、海洋食品)加工中应用。提出DPCD技术未来发展可能需要解决的问题。%Dense phase carbon dioxide(DPCD)is one of the verypromising food non-thermal processing technologies, which was mainly used to inactivate microorganism and enzymein food. The paper reviews the progress oflast decademade in the basic research and application research of DPCD technology at home and abroad. The basic research fields of DPCD technology include phase equilibrium between DPCD and food system, effect and mechanism of inactivation microbial vegetative and spore by DPCD, effect and mechanism of inactivation enzyme by DPCD.The application research fields of DPCD technology include liquid food(fruit and vegetable juice,beer, milk)and solid food(fresh cut fruit and vegetable,meat,seafood) processing. Finally,some problems to be solved are discussed on the development of DPCD technology in future. The reviews will provide the reference for the research and application of DPCD in food processing.

  5. Development of high performance nano-porous polyethersulfone ultrafiltration membranes with hydrophilic surface and superior antifouling properties

    Energy Technology Data Exchange (ETDEWEB)

    Rahimpour, Ahmad, E-mail: ahmadrahimpour@yahoo.com [Nanobiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of); Madaeni, Sayed Siavash [Membrane Research Center, Department of Chemical Engineering, Razi University, Kermanshah (Iran, Islamic Republic of); Jahanshahi, Mohsen [Nanobiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of); Mansourpanah, Yaghoub [Department of Chemistry, Faculty of Science, Lorestan University, Khorramabad (Iran, Islamic Republic of); Mortazavian, Narmin [Nanobiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of)

    2009-08-30

    Hydrophilic nano-porous polyethersulfone ultrafiltration membranes were developed for milk concentration. The membranes were prepared from new dope solution containing polyethersulfone (PES)/polyvinylpirrolidone (PVP)/polyethyleneglycole (PEG)/cellulose acetate phthalate (CAP)/acrylic acid/Triton X-100 using phase inversion induced by immersion precipitation technique. This casting solution leads to formation of new hydrophilic membranes. The morphological studies were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the hydrophilicity and performance of membranes were examined by contact angel measurements and cross-flow filtration (pure water flux, milk water permeation, protein rejection and antifouling measurements). The contact angle measurements indicate that a surface with superior hydrophilicity was obtained for PES membranes. Two concentrations of PES (16 and 14.4 wt.%) and two different non-solvents (pure water and mixtures of water and IPA) were used for preparation of membranes. The morphological studies showed that the higher concentration of PES and the presence of IPA in the gelation media results in formation of a membrane with a dense top and sub-layer with small pores on the surface. The pure water flux of membranes was decreased when higher polymer concentration and mixtures of water and IPA were employed for membrane formation. On the other hand, the milk water permeation and protein rejection were increased using mixtures of water and IPA as non-solvent. Furthermore, the fouling analysis of the membranes demonstrated that the membrane surface with fewer tendencies for fouling was obtained.

  6. Probing Cold Dense Nuclear Matter

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, Ramesh; Shneor, R.; Monaghan, Peter; Anderson, Bryon; Aniol, Konrad; Annand, John; Arrington, John; Benaoum, Hachemi; Benmokhtar, Fatiha; Bertozzi, William; Boeglin, Werner; Chen, Jian-Ping; Choi, Seonho; Cisbani, Evaristo; Craver, Brandon; Frullani, Salvatore; Garibaldi, Franco; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Hansen, Jens-Ole; Higinbotham, Douglas; Holmstrom, Timothy; Ibrahim, Hassan; Igarashi, Ryuichi; De Jager, Cornelis; Jans, Eddy; Jiang, Xiaodong; Kaufman, Lisa; Kelleher, Aidan; Kolarkar, Ameya; Kumbartzki, Gerfried; LeRose, John; Lindgren, Richard; Liyanage, Nilanga; Margaziotis, Demetrius; Markowitz, Pete; Marrone, Stefano; Mazouz, Malek; Meekins, David; Michaels, Robert; Moffit, Bryan; Perdrisat, Charles; Piasetzky, Eliazer; Potokar, Milan; Punjabi, Vina; Qiang, Yi; Reinhold, Joerg; Ron, Guy; Rosner, Guenther; Saha, Arunava; Sawatzky, Bradley; Shahinyan, Albert; Sirca, Simon; Slifer, Karl; Solvignon, Patricia; Sulkosky, Vince; Sulkosky, Vincent; Sulkosky, Vince; Sulkosky, Vincent; Urciuoli, Guido; Voutier, Eric; Watson, John; Weinstein, Lawrence; Wojtsekhowski, Bogdan; Wood, Stephen; Zheng, Xiaochao; Zhu, Lingyan

    2008-06-01

    The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

  7. Probing Cold Dense Nuclear Matter

    CERN Document Server

    Subedi, R; Monaghan, P; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertozzi, W; Boeglin, W; Chen, J -P; Choi, Seonho; Cisbani, E; Craver, B; Frullani, S; Garibaldi, F; Gilad, S; Gilman, R; Glamazdin, O; Hansen, J -O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; De Jager, C W; Jans, E; Jiang, X; Kaufman, L; Kelleher, A; Kolarkar, A; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Ron, G; Rosner, G; Saha, A; Sawatzky, B; Shahinyan, A; Širca, S; Slifer, K; Solvignon, P; Sulkosky, V; Urciuoli, G; Voutier, E; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Zheng, X -C; Zhu, L; 10.1126/science.1156675

    2009-01-01

    The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, where a proton is knocked-out of the nucleus with high momentum transfer and high missing momentum, show that in 12C the neutron-proton pairs are nearly twenty times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.

  8. Dilatons in Dense Baryonic Matter

    CERN Document Server

    Lee, Hyun Kyu

    2013-01-01

    We discuss the role of dilaton, which is supposed to be representing a special feature of scale symmetry of QCD, trace anomaly, in dense baryonic matter. The idea that the scale symmetry breaking of QCD is responsible for the spontaneous breaking of chiral symmetry is presented along the similar spirit of Freund-Nambu model. The incorporation of dilaton field in the hidden local symmetric parity doublet model is briefly sketched with the possible role of dilaton at high density baryonic matter, the emergence of linear sigma model in dilaton limit.

  9. Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: a novel platform for eco-friendly biofouling mitigation.

    Science.gov (United States)

    Wibisono, Yusuf; Yandi, Wetra; Golabi, Mohsen; Nugraha, Roni; Cornelissen, Emile R; Kemperman, Antoine J B; Ederth, Thomas; Nijmeijer, Kitty

    2015-03-15

    Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG10MA), cationic (polyDMAEMA) and anionic (polySPMA) hydrogels have been successfully grafted onto polypropylene (PP) feed spacers via plasma-mediated UV-polymerization. These coatings maintained their chemical stability after 7 days incubation in neutral (pH 7), acidic (pH 5) and basic (pH 9) environments. Anti-biofouling properties of these coatings were evaluated by Escherichia coli attachment assay and nanofiltration experiments at a TMP of 600 kPag using tap water with additional nutrients as feed and by using optical coherence tomography. Especially the anionic polySPMA-coated PP feed spacer shows reduced attachment of E. coli and biofouling in the spacer-filled narrow channels resulting in delayed biofilm growth. Employing this highly hydrophilic coating during removal of biofouling by two-phase flow cleaning also showed enhanced cleaning efficiency, feed channel pressure drop and flux recoveries. The strong hydrophilic nature and the presence of negative charge on polySPMA are most probably responsible for the improved antifouling behavior. A combination of polySPMA-coated PP feed spacers and two-phase flow cleaning therefore is promising and an environmentally friendly approach to control biofouling in NF/RO systems employing spiral-wound membrane modules.

  10. A miniature condensed-phase membrane introduction mass spectrometry (CP-MIMS) probe for direct and on-line measurements of pharmaceuticals and contaminants in small, complex samples.

    Science.gov (United States)

    Duncan, Kyle D; Willis, Megan D; Krogh, Erik T; Gill, Christopher G

    2013-06-15

    High-throughput, automated analytical measurements are desirable in many analytical scenarios, as are rapid sample pre-screening techniques to identify 'positive' samples for subsequent measurements using more time-consuming conventional methodologies (e.g., liquid chromatography/mass spectrometry (LC/MS)). A miniature condensed-phase membrane introduction mass spectrometry (CP-MIMS) probe for the direct and continuous, on-line measurement of pharmaceuticals and environmental contaminants in small, complex samples is presented. A miniature polydimethylsiloxane hollow fibre membrane (PDMS-HFM) probe is coupled with an electrospray ionization (ESI) triple quadrupole mass spectrometer. Analytes are transported from the probe to the ESI source by a methanol acceptor phase. The probe can be autosampler mounted and directly inserted in small samples (≥400 μL) allowing continuous and simultaneous pptr-ppb level detection of target analytes (chlorophenols, triclosan, gemfibrozil, nonylphenol) in complex samples (artificial urine, beer, natural water, waste water, plant tissue). The probe has been characterized and optimized for acceptor phase flow rate, sample mixing and probe washing. Signal response times, detection limits and calibration data are given for selected ion monitoring (SIM) and tandem mass spectrometry (MS/MS) measurements of target analytes at trace levels. Comparisons with flow cell type CP-MIMS systems are given. Analyte depletion effects are evaluated for small samples (≥400 μL). On-line measurements in small volumes of complex samples, temporally resolved reaction monitoring and in situ/in vivo demonstrations are presented. The miniature CP-MIMS probe developed was successfully used for the direct, on-line detection of target analytes in small volumes (40 mL to 400 μL) of complex samples at pptr to low ppb levels. The probe can be readily automated as well as deployed for in situ/in vivo monitoring, including reaction monitoring, small sample

  11. A comparative differential scanning calorimetry study of the effects of cholesterol and various oxysterols on the thermotropic phase behavior of dipalmitoylphosphatidylcholine bilayer membranes.

    Science.gov (United States)

    Benesch, Matthew G K; McElhaney, Ronald N

    2016-02-01

    We have carried out a comparative differential scanning calorimetric (DSC) study of the effects of cholesterol (C) and the eight most physiologically relevant oxysterols on the thermotropic phase behavior of dipalmitoylphosphatidylcholine (DPPC) bilayer membranes. The structures of these oxysterols differ from that of C by the presence of additional hydroxyl, keto or epoxy groups on the steroid ring system or by the presence of a hydroxyl group in the alkyl side chain. In general, the progressive incorporation of these oxysterols reduces the temperature, cooperativity and enthalpy of the pretransition of DPPC to a greater extent than C, indicating that their presence thermally destabilizes and disorders the gel states of DPPC bilayers to a greater extent than C. Similarly, the incorporation of these oxysterols either increases the temperature of the broad component of the main phase transition to a smaller extent than C or actually decreases it. Again, this indicates that the presence of these compounds is less effective at thermally stabilizing and ordering the sterol-rich domains of DPPC bilayers than is C itself. Moreover, the incorporation of these oxysterols decrease the cooperativity and enthalpy of the main phase transition of DPPC to a smaller extent than C, indicating that they are somewhat less miscible in fluid DPPC bilayers than is C. Particularly notable in this regard is 25-hydroxycholesterol, which exhibits a markedly reduced miscibility in both gel and fluid DPPC bilayers compared to C itself. In general, the effectiveness of these oxysterols in stabilizing and ordering DPPC bilayers decreases as their rate of interbilayer exchange and the polarity of the oxysterol increases. We close by providing a tentative molecular explanation for the results of our DSC studies and of those of previous biophysical studies of the effects of various oxysterol on lipid bilayer model membranes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Proteomic analysis of oil body membrane proteins accompanying the onset of desiccation phase during sunflower seed development.

    Science.gov (United States)

    Thakur, Anita; Bhatla, Satish C

    2015-01-01

    A noteworthy metabolic signature accompanying oil body (OB) biogenesis during oilseed development is associated with the modulation of the oil body membranes proteins. Present work focuses on 2-dimensional polyacrylamide gel electrophoresis (2-D PAGE)-based analysis of the temporal changes in the OB membrane proteins analyzed by LC-MS/MS accompanying the onset of desiccation (20-30 d after anthesis; DAA) in the developing seeds of sunflower (Helianthus annuus L.). Protein spots unique to 20-30 DAA stages were picked up from 2-D gels for identification and the identified proteins were categorized into 7 functional classes. These include proteins involved in energy metabolism, reactive oxygen scavenging, proteolysis and protein turnover, signaling, oleosin and oil body biogenesis-associated proteins, desiccation and cytoskeleton. At 30 DAA stage, exclusive expressions of enzymes belonging to energy metabolism, desiccation and cytoskeleton were evident which indicated an increase in the metabolic and enzymatic activity in the cells at this stage of seed development (seed filling). Increased expression of cruciferina-like protein and dehydrin at 30 DAA stage marks the onset of desiccation. The data has been analyzed and discussed to highlight desiccation stage-associated metabolic events during oilseed development.

  13. (Ce,Gd)O2−δ-based dual phase membranes for oxygen separation

    DEFF Research Database (Denmark)

    Samson, Alfred Junio; Søgaard, Martin; Hendriksen, Peter Vang

    2014-01-01

    Composite membranes based on selected combinations of the ionic conductor Ce0.9Gd0.1O1.95 (CGO) and electronic/mixed conductors (Ag–CuO, LaCoO3 (LC), La0.6Sr0.4CoO3−δ (LSC), La0.6Sr0.4FeO3−δ (LSF), (La0.6Sr0.4)0.99Co0.2Fe0.8O3−δ (LSCF), and La0.75Sr0.25Cr0.97V0.03O3−δ (LSCrV)) were prepared...... CGO and the other materials were detected by X-ray diffraction. The highest flux of 1.53×10−7molcm−2s−1 (0.21Nmlcm−2min−1) at 800°C under N2/air was obtained for a CGO/LSC composite with a thickness of ca. 1mm. The oxygen flux of the CGO/LSC membrane exhibited no degradation after 300h of operation...

  14. Predicted reentrant melting of dense hydrogen at ultra-high pressures

    Science.gov (United States)

    Geng, Hua Y.; Wu, Q.

    2016-11-01

    The phase diagram of hydrogen is one of the most important challenges in high-pressure physics and astrophysics. Especially, the melting of dense hydrogen is complicated by dimer dissociation, metallization and nuclear quantum effect of protons, which together lead to a cold melting of dense hydrogen when above 500 GPa. Nonetheless, the variation of the melting curve at higher pressures is virtually uncharted. Here we report that using ab initio molecular dynamics and path integral simulations based on density functional theory, a new atomic phase is discovered, which gives an uplifting melting curve of dense hydrogen when beyond 2 TPa, and results in a reentrant solid-liquid transition before entering the Wigner crystalline phase of protons. The findings greatly extend the phase diagram of dense hydrogen, and put metallic hydrogen into the group of alkali metals, with its melting curve closely resembling those of lithium and sodium.

  15. Predicted reentrant melting of dense hydrogen at ultra-high pressures

    CERN Document Server

    Geng, Hua Y

    2016-01-01

    The phase diagram of hydrogen is one of the most important challenges in high-pressure physics and astrophysics. Especially, the melting of dense hydrogen is complicated by dimer dissociation, metallization and nuclear quantum effect of protons, which together lead to a cold melting of dense hydrogen when above 500 GPa. Nonetheless, the variation of the melting curve at higher pressures is virtually uncharted. Here we report that using ab initio molecular dynamics and path integral simulations based on density functional theory, a new atomic phase is discovered, which gives an uplifting melting curve of dense hydrogen when beyond 2 TPa, and results in a reentrant solid-liquid transition before entering the Wigner crystalline phase of protons. The findings greatly extend the phase diagram of dense hydrogen, and put metallic hydrogen into the group of alkali metals, with its melting curve closely resembling those of lithium and sodium.

  16. Relevance of diffusion through bacterial spore coats/membranes and the associated concentration boundary layers in the initial lag phase of inactivation: a case study for Bacillus subtilis with ozone and monochloramine.

    Science.gov (United States)

    Fernando, W J N; Othman, R

    2006-02-01

    Disinfectants are generally used to inactivate microorganisms in solutions. The process of inactivation involves the disinfectant in the liquid diffusing towards the bacteria sites and thereafter reacting with bacteria at rates determined by the respective reaction rates. Such processes have demonstrated an initial lag phase followed by an active depletion phase of bacteria. This paper attempts to study the importance of the combined effects of diffusion of the disinfectant through the outer membrane of the bacteria and transport through the associated concentration boundary layers (CBLs) during the initial lag phase. Mathematical equations are developed correlating the initial concentration of the disinfectant with time required for reaching a critical concentration (C*) at the inner side of the membrane of the cell based on diffusion of disinfectant through the outer membranes of the bacteria and the formation of concentration boundary layers on both sides of the membranes. Experimental data of the lag phases of inactivation already available in the literature for inactivation of Bacillus subtilis spores with ozone and monochloramine are tested with the equations. The results seem to be in good agreement with the theoretical equations indicating the importance of diffusion process across the outer cell membranes and the resulting CBL's during the lag phase of disinfection.

  17. Time to Definitive Health-Related Quality of Life Score Deterioration in Patients with Resectable Metastatic Colorectal Cancer Treated with FOLFOX4 versus Sequential Dose-Dense FOLFOX7 followed by FOLFIRI: The MIROX Randomized Phase III Trial.

    Directory of Open Access Journals (Sweden)

    Zeinab Hamidou

    Full Text Available We previously showed that a sequential chemotherapy with dose-dense oxaliplatin (FOLFOX7 and irinotecan (FOLFIRI; irinotecan plus 5-fluorouracil/leucovorin is not superior to FOLFOX4 in patients at advanced stage of colorectal cancer with liver metastases. Here we aimed to determine whether time to health-related quality of life (HRQoL score definitive deterioration (TUDD differs by study arm.HRQoL was evaluated using the European Organization for Research and Treatment of Cancer (EORTC QLQ-C30 at baseline and every 4 cycles until the end of the study or death. Functional scale, symptom scale, global health status, and financial difficulties were analyzed. The TUDD was defined as the time interval between randomization and the first decrease in HRQoL score ≥ 5-point with no further improvement in HRQoL score ≥ 5 points or any further HRQoL data. TUDD was estimated using the Kaplan-Meier method and the long-rank test. Cox regression analyses were used to identify HRQoL items influencing TUDD. Sensitivity analyses were done using a multiple imputation method and different definitions of TUDD.Of the 284 patients, 171 (60.2% completed HRQoL questionnaires. Cox multivariate analysis showed no statistically significant difference in TUDD for most of the QLQ-C30 scales between treatments. Patients with dyspnea and those without symptoms at baseline had a significantly longer TUDD when there was a delay >12 months between diagnosis of the primary tumor and metastases (HR 0.48 [0.26-0.89] and when there was diarrhea (HR 0.59 [0.36-0.96], respectively.This study shows that TUDD does not differ significantly according to type of treatment. The TUDD method produces meaningful longitudinal HRQoL results that may facilitate effective clinical decision making in patients with mCRC.ClinicalTrials.gov NCT00268398.

  18. Capture, isolation and electrochemical detection of industrially-relevant engineered aerosol nanoparticles using poly (amic) acid, phase-inverted, nano-membranes

    Energy Technology Data Exchange (ETDEWEB)

    Okello, Veronica A. [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Gass, Samuel; Pyrgiotakis, Georgios [Center for Nanotechnology and Nanotoxicology, Harvard School of Public Health, Department of Environmental Health, 665 Huntington Avenue, Boston, MA 02115-6021 (United States); Du, Nian; Lake, Andrew; Kariuki, Victor [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Sotiriou, Georgios A. [Center for Nanotechnology and Nanotoxicology, Harvard School of Public Health, Department of Environmental Health, 665 Huntington Avenue, Boston, MA 02115-6021 (United States); Addolorato, Jessica [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Demokritou, Philip, E-mail: pdemokri@hsph.harvard.edu [Center for Nanotechnology and Nanotoxicology, Harvard School of Public Health, Department of Environmental Health, 665 Huntington Avenue, Boston, MA 02115-6021 (United States); Sadik, Omowunmi A., E-mail: osadik@binghamton.edu [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States)

    2014-08-30

    Graphical abstract: - Highlights: • Exposure level assessment of aerosol nanoparticles reported using Harvard's VENGES. • Device equipped with pi-conjugated conducting PAA membrane filters/sensor arrays. • PAA membrane motifs used to capture, isolate and detect the nanoparticles. • Manipulating the PAA delocalized π electron enabled electrocatalytic detection. • Fe{sub 2}O{sub 3}, ZnO and TiO{sub 2} quantified using impedance spectroscopy and cyclic voltammetry. - Abstract: Workplace exposure to engineered nanoparticles (ENPs) is a potential health and environmental hazard. This paper reports a novel approach for tracking hazardous airborne ENPs by applying online poly (amic) acid membranes (PAA) with offline electrochemical detection. Test aerosol (Fe{sub 2}O{sub 3}, TiO{sub 2} and ZnO) nanoparticles were produced using the Harvard (Versatile Engineered Generation System) VENGES system. The particle morphology, size and elemental composition were determined using SEM, XRD and EDS. The PAA membrane electrodes used to capture the airborne ENPs were either stand-alone or with electron-beam gold-coated paper substrates. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to conceptually illustrate that exposure levels of industry-relevant classes of airborne nanoparticles could be captured and electrochemically detected at PAA membranes filter electrodes. CV parameters showed that PAA catalyzed the reduction of Fe{sub 2}O{sub 3} to Fe{sup 2+} with a size-dependent shift in reduction potential (E{sup 0}). Using the proportionality of peak current to concentration, the amount of Fe{sub 2}O{sub 3} was found to be 4.15 × 10{sup −17} mol/cm{sup 3} PAA electrodes. Using EIS, the maximum phase angle (Φ{sub max}) and the interfacial charge transfer resistance (R{sub ct}) increased significantly using 100 μg and 1000 μg of TiO{sub 2} and ZnO respectively. The observed increase in Φ{sub max} and R{sub ct} at increasing

  19. Emulsification using microporous membranes

    Directory of Open Access Journals (Sweden)

    Goran T. Vladisavljević

    2011-10-01

    Full Text Available Membrane emulsification is a process of injecting a pure dispersed phase or pre-emulsion through a microporous membrane into the continuous phase. As a result of the immiscibility of the two phases, droplets of the dispersed phase are formed at the outlets of membrane pores. The droplets formed in the process are removed from the membrane surface by applying cross-flow or stirring of the continuous phase or using a dynamic (rotating or vibrating membrane. The most commonly used membrane for emulsification is the Shirasu Porous Glass (SPG membrane, fabricated through spinodal decomposition in a melt consisting of Japanese volcanic ash (Shirasu, boric acid and calcium carbonate. Microsieve membranes are increasingly popular as an alternative to highly tortuous glass and ceramic membranes. Microsieves are usually fabricated from nickel by photolithography and electroplating or they can be manufactured from silicon nitride via Reactive Ion Etching (RIE. An advantage of microsieves compared to the SPG membrane is in much higher transmembrane fluxes and higher tolerance to fouling by the emulsion ingredients due to the existence of short, straight through pores. Unlike conventional emulsification devices such as high-pressure valve homogenisers and rotor-stator devices, membrane emulsification devices permit a precise control over the mean pore size over a wide range and during the process insignificant amount of energy is dissipated as heat. The drop size is primarily determined by the pore size, but it depends also on other parameters, such as membrane wettability, emulsion formulation, shear stress on the membrane surface, transmembrane pressure, etc.

  20. Multi-scale First-Principles Modeling of Three-Phase System of Polymer Electrolyte Membrane Fuel Cel

    Energy Technology Data Exchange (ETDEWEB)

    Brunello, Giuseppe; Choi, Ji; Harvey, David; Jang, Seung

    2012-07-01

    The three-phase system consisting of Nafion, graphite and platinum in the presence of water is studied using molecule dynamics simulation. The force fields describing the molecular interaction between the components in the system are developed to reproduce the energies calculated from density functional theory modeling. The configuration of such complicated three-phase system is predicted through MD simulations. The nanophase-segregation and transport properties are investigated from the equilibrium state. The coverage of the electrolyte on the platinum surface and the dissolution of oxygen are analyzed.