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Sample records for affect membrane performance

  1. Factors affecting alcohol-water pervaporation performance of hydrophobic zeolite-silicone rubber mixed matrix membranes

    EPA Science Inventory

    Mixed matrix membranes (MMMs) consisting of ZSM-5 zeolite particles dispersed in silicone rubber exhibited ethanol-water pervaporation permselectivities up to 5 times that of silicone rubber alone and 3 times higher than simple vapor-liquid equilibrium (VLE). A number of conditi...

  2. Comparison of ceftiofur hydrochloride and estradiol cypionate for metritis prevention and reproductive performance in dairy cows affected with retained fetal membranes.

    PubMed

    Risco, C A; Hernandez, J

    2003-06-01

    The objective of this study was to compare the effect of ceftiofur hydrochloride and estradiol cypionate (ECP) administration for metritis prevention and reproductive performance in dairy cows affected with retained fetal membranes (RFMs). After parturition, 97 dairy cows affected with RFM from a single dairy herd were randomly allocated to 1 of 3 treatment groups. Cows in-group 1 (n=31) were treated daily for 5 days with ceftiofur hydrochloride (2.2mg/kg, i.m.); cows in group 2 (n=33) were treated once with ECP (4 mg, i.m.); and cows in group 3 (n=33) were not treated. The proportion of cows with metritis, uterine involution patterns and the calving-to-conception interval were compared between groups. The proportion of cows that developed metritis was significantly different (P<0.05) in cows treated with ceftiofur hydrochloride (13%), compared with cows treated with ECP (42%) or cows that received no treatment (42%). Uterine involution patterns (i.e. median time to complete retraction of the uterus and mean diameter measure of cervix and uterine horns) were not significantly different between groups. Cows treated with ECP were 0.40 times as likely to conceive as control cows (P=0.05); median time to conception in cows treated with ECP (192 days) was longer, compared to control cows (124 days). We conclude that systemic administration of ceftioufur hydrochloride is beneficial for prevention of metritis, but its effect on reproductive performance was not significantly different to that of ECP or no treatment. In addition, administration of ECP did not have beneficial effects on metritis prevention and reproductive performance.

  3. Buffers affect the bending rigidity of model lipid membranes.

    PubMed

    Bouvrais, Hélène; Duelund, Lars; Ipsen, John H

    2014-01-14

    In biophysical and biochemical studies of lipid bilayers the influence of the used buffer is often ignored or assumed to be negligible on membrane structure, elasticity, or physical properties. However, we here present experimental evidence, through bending rigidity measurements performed on giant vesicles, of a more complex behavior, where the buffering molecules may considerably affect the bending rigidity of phosphatidylcholine bilayers. Furthermore, a synergistic effect on the bending modulus is observed in the presence of both salt and buffer molecules, which serves as a warning to experimentalists in the data interpretation of their studies, since typical lipid bilayer studies contain buffer and ion molecules.

  4. Quantum Tunneling Affects Engine Performance.

    PubMed

    Som, Sibendu; Liu, Wei; Zhou, Dingyu D Y; Magnotti, Gina M; Sivaramakrishnan, Raghu; Longman, Douglas E; Skodje, Rex T; Davis, Michael J

    2013-06-20

    We study the role of individual reaction rates on engine performance, with an emphasis on the contribution of quantum tunneling. It is demonstrated that the effect of quantum tunneling corrections for the reaction HO2 + HO2 = H2O2 + O2 can have a noticeable impact on the performance of a high-fidelity model of a compression-ignition (e.g., diesel) engine, and that an accurate prediction of ignition delay time for the engine model requires an accurate estimation of the tunneling correction for this reaction. The three-dimensional model includes detailed descriptions of the chemistry of a surrogate for a biodiesel fuel, as well as all the features of the engine, such as the liquid fuel spray and turbulence. This study is part of a larger investigation of how the features of the dynamics and potential energy surfaces of key reactions, as well as their reaction rate uncertainties, affect engine performance, and results in these directions are also presented here.

  5. How Lipid Membranes Affect Pore Forming Toxin Activity.

    PubMed

    Rojko, Nejc; Anderluh, Gregor

    2015-12-15

    , events associated with pore formation can modulate properties of the lipid membrane and affect its organization. Model membranes do not necessarily reproduce the physicochemical properties of the native cellular membrane, and caution is needed when transferring results from model to native lipid membranes. In this context, the utilization of novel approaches that enable studying PFTs on living cells at a single molecule level should reveal complex protein-lipid membrane interactions in greater detail.

  6. Gas separation performance of inorganic polyphosphazene membranes

    SciTech Connect

    Stone, M.L.

    1995-07-01

    The objective of this research program was to develop, characterize, and evaluate the potential of phosphazene polymers for separations performed in harsh environments. The program was divided into two general areas, gas separations and metal ion separations involving aqueous solutions. Each of these two areas is the subject of a topical report; this report deals with the gas separations. Throughout the world, there is rapidly growing interest in membrane separation as an energy efficient way to separate components of a process stream or waste stream, such as in desalination of water or clarification of fruit juices. In some cases membranes perform separations that are otherwise very difficult, such as breaking azeotropes. In the early stages of the work reported here, there was interest in separating acid gases from process flue gases and in natural gas sweetening. As a result, research was undertaken to characterize membrane performance. First, a pure gas test apparatus was developed to determine the permeabilities of a number of gases through various membranes at a variety of temperatures. Second, an automated mixed gas test cell was developed in which membranes could be exposed to mixtures of pairs of gases. Each of these approaches has its advantages and each will be discussed separately.

  7. Ceramic membranes: The effects of deposition and drying conditions on membrane morphology and performance

    NASA Astrophysics Data System (ADS)

    Webster, Elizabeth T.

    a transport model to characterize the mechanisms of fluid flow and the morphologies of the membranes. Electron microscopy was employed to evaluate membrane coverage and to identify defects in the membranes. The results of the factorial experiments indicate that membrane performance is strongly affected by humidity during deposition and drying. These results underscore the importance of controlling process humidity during fabrication of ceramic membranes.

  8. SPREADSHEET BASED SCALING CALCULATIONS AND MEMBRANE PERFORMANCE

    EPA Science Inventory

    Many membrane element manufacturers provide a computer program to aid buyers in the use of their elements. However, to date there are few examples of fully integrated public domain software available for calculating reverse osmosis and nanofiltration system performance. The Total...

  9. Does Membrane Thickness Affect the Transport of Selective Ions Mediated by Ionophores in Synthetic Membranes?

    PubMed

    Lomora, Mihai; Dinu, Ionel Adrian; Itel, Fabian; Rigo, Serena; Spulber, Mariana; Palivan, Cornelia G

    2015-08-31

    Biomimetic polymer nanocompartments (polymersomes) with preserved architecture and ion-selective membrane permeability represent cutting-edge mimics of cellular compartmentalization. Here it is studied whether the membrane thickness affects the functionality of ionophores in respect to the transport of Ca(2+) ions in synthetic membranes of polymersomes, which are up to 2.6 times thicker than lipid membranes (5 nm). Selective permeability toward calcium ions is achieved by proper insertion of ionomycin, and demonstrated by using specific fluorescence markers encapsulated in their inner cavities. Preservation of polymersome architecture is shown by a combination of light scattering, transmission electron microscopy, and fluorescence spectroscopy. By using a combination of stopped-flow and fluorescence spectroscopy, it is shown that ionomycin can function and transport calcium ions across polymer membranes with thicknesses in the range 10.7-13.4 nm (7.1-8.9 times larger than the size of the ionophore). Thicker membranes induce a decrease in transport, but do not block it due to the intrinsic flexibility of these synthetic membranes. The design of ion selective biomimetic nanocompartments represents a new path toward the development of cellular ion nanosensors and nano-reactors, in which calcium sensitive biomacromolecules can be triggered for specific biological functions.

  10. The Zeamine Antibiotics Affect the Integrity of Bacterial Membranes

    PubMed Central

    Masschelein, Joleen; Clauwers, Charlien; Stalmans, Karen; Nuyts, Koen; De Borggraeve, Wim; Briers, Yves; Aertsen, Abram; Michiels, Chris W.

    2014-01-01

    The zeamines (zeamine, zeamine I, and zeamine II) constitute an unusual class of cationic polyamine-polyketide-nonribosomal peptide antibiotics produced by Serratia plymuthica RVH1. They exhibit potent bactericidal activity, killing a broad range of Gram-negative and Gram-positive bacteria, including multidrug-resistant pathogens. Examination of their specific mode of action and molecular target revealed that the zeamines affect the integrity of cell membranes. The zeamines provoke rapid release of carboxyfluorescein from unilamellar vesicles with different phospholipid compositions, demonstrating that they can interact directly with the lipid bilayer in the absence of a specific target. DNA, RNA, fatty acid, and protein biosynthetic processes ceased simultaneously at subinhibitory levels of the antibiotics, presumably as a direct consequence of membrane disruption. The zeamine antibiotics also facilitated the uptake of small molecules, such as 1-N-phenylnaphtylamine, indicating their ability to permeabilize the Gram-negative outer membrane (OM). The valine-linked polyketide moiety present in zeamine and zeamine I was found to increase the efficiency of this process. In contrast, translocation of the large hydrophilic fluorescent peptidoglycan binding protein PBDKZ-GFP was not facilitated, suggesting that the zeamines cause subtle perturbation of the OM rather than drastic alterations or defined pore formation. At zeamine concentrations above those required for growth inhibition, membrane lysis occurred as indicated by time-lapse microscopy. Together, these findings show that the bactericidal activity of the zeamines derives from generalized membrane permeabilization, which likely is initiated by electrostatic interactions with negatively charged membrane components. PMID:25452285

  11. Electrospun polyethersulfone affinity membrane: membrane preparation and performance evaluation.

    PubMed

    Ma, Zuwei; Lan, Zhengwei; Matsuura, Takeshi; Ramakrishna, Seeram

    2009-11-01

    Non-woven polyethersulfone (PES) membranes were prepared by electrospinning. After heat treatment and surface activation, the membranes were covalently functionalized with ligands to be used as affinity membranes. The membranes were characterized in terms of fiber diameter, porosity, specific area, pore size, ligand density and binding capacities. To evaluate the binding efficiency of the membrane, dynamic adsorption of bovine serum albumin (BSA) on the Cibacron blue F3GA (CB) functionalized PES membrane was studied. Experimental breakthrough curves were fitted with the theoretical curves based on the plate model to estimate plate height (H(p)) of the affinity membrane. The high value of H(p) (1.6-8 cm) of the affinity membrane implied a poor dynamic binding efficiency, which can be explained by the intrinsic microstructures of the material. Although the electrospun membrane might not be an ideal candidate for the preparative affinity membrane chromatography for large-scale production, it still can be used for fast small-scale protein purification in which a highly efficient binding is not required. Spin columns packed with protein A/G immobilized PES membranes were demonstrated to be capable of binding IgG specifically. SDS-PAGE results demonstrated that the PES affinity membrane had high specific binding selectivity for IgG molecules and low non-specific protein adsorption. Compared with other reported affinity membranes, the PES affinity membrane had a comparable IgG binding capacity of 4.5 mg/ml, and had a lower flow through pressure drop due to its larger pore size. In conclusion, the novel PES affinity membrane is an ideal spin column packing material for fast protein purification.

  12. Iron Deprivation Affects Drug Susceptibilities of Mycobacteria Targeting Membrane Integrity

    PubMed Central

    Pal, Rahul; Hameed, Saif; Fatima, Zeeshan

    2015-01-01

    Multidrug resistance (MDR) acquired by Mycobacterium tuberculosis (MTB) through continuous deployment of antitubercular drugs warrants immediate search for novel targets and mechanisms. The ability of MTB to sense and become accustomed to changes in the host is essential for survival and confers the basis of infection. A crucial condition that MTB must surmount is iron limitation, during the establishment of infection, since iron is required by both bacteria and humans. This study focuses on how iron deprivation affects drug susceptibilities of known anti-TB drugs in Mycobacterium smegmatis, a “surrogate of MTB.” We showed that iron deprivation leads to enhanced potency of most commonly used first line anti-TB drugs that could be reverted upon iron supplementation. We explored that membrane homeostasis is disrupted upon iron deprivation as revealed by enhanced membrane permeability and hypersensitivity to membrane perturbing agent leading to increased passive diffusion of drug and TEM images showing detectable differences in cell envelope thickness. Furthermore, iron seems to be indispensable to sustain genotoxic stress suggesting its possible role in DNA repair machinery. Taken together, we for the first time established a link between cellular iron and drug susceptibility of mycobacteria suggesting iron as novel determinant to combat MDR. PMID:26779346

  13. Spreadsheet Based Scaling Calculations and Membrane Performance

    SciTech Connect

    Wolfe, T D; Bourcier, W L; Speth, T F

    2000-12-28

    Many membrane element manufacturers provide a computer program to aid buyers in the use of their elements. However, to date there are few examples of fully integrated public domain software available for calculating reverse osmosis and nanofiltration system performance. The Total Flux and Scaling Program (TFSP), written for Excel 97 and above, provides designers and operators new tools to predict membrane system performance, including scaling and fouling parameters, for a wide variety of membrane system configurations and feedwaters. The TFSP development was funded under EPA contract 9C-R193-NTSX. It is freely downloadable at www.reverseosmosis.com/download/TFSP.zip. TFSP includes detailed calculations of reverse osmosis and nanofiltration system performance. Of special significance, the program provides scaling calculations for mineral species not normally addressed in commercial programs, including aluminum, iron, and phosphate species. In addition, ASTM calculations for common species such as calcium sulfate (CaSO{sub 4}{times}2H{sub 2}O), BaSO{sub 4}, SrSO{sub 4}, SiO{sub 2}, and LSI are also provided. Scaling calculations in commercial membrane design programs are normally limited to the common minerals and typically follow basic ASTM methods, which are for the most part graphical approaches adapted to curves. In TFSP, the scaling calculations for the less common minerals use subsets of the USGS PHREEQE and WATEQ4F databases and use the same general calculational approach as PHREEQE and WATEQ4F. The activities of ion complexes are calculated iteratively. Complexes that are unlikely to form in significant concentration were eliminated to simplify the calculations. The calculation provides the distribution of ions and ion complexes that is used to calculate an effective ion product ''Q.'' The effective ion product is then compared to temperature adjusted solubility products (Ksp's) of solids in order to calculate a Saturation Index (SI) for each solid of

  14. Evaluation method of membrane performance in membrane distillation process for seawater desalination.

    PubMed

    Chung, Seungjoon; Seo, Chang Duck; Choi, Jae-Hoon; Chung, Jinwook

    2014-01-01

    Membrane distillation (MD) is an emerging desalination technology as an energy-saving alternative to conventional distillation and reverse osmosis method. The selection of appropriate membrane is a prerequisite for the design of an optimized MD process. We proposed a simple approximation method to evaluate the performance of membranes for MD process. Three hollow fibre-type commercial membranes with different thicknesses and pore sizes were tested. Experimental results showed that one membrane was advantageous due to the highest flux, whereas another membrane was due to the lowest feed temperature drop. Regression analyses and multi-stage calculations were used to account for the trade-offeffects of flux and feed temperature drop. The most desirable membrane was selected from tested membranes in terms of the mean flux in a multi-stage process. This method would be useful for the selection of the membranes without complicated simulation techniques.

  15. Application of forward osmosis membrane technology for oil sands process-affected water desalination.

    PubMed

    Jiang, Yaxin; Liang, Jiaming; Liu, Yang

    2016-01-01

    The extraction process used to obtain bitumen from the oil sands produces large volumes of oil sands process-affected water (OSPW). As a newly emerging desalination technology, forward osmosis (FO) has shown great promise in saving electrical power requirements, increasing water recovery, and minimizing brine discharge. With the support of this funding, a FO system was constructed using a cellulose triacetate FO membrane to test the feasibility of OSPW desalination and contaminant removal. The FO systems were optimized using different types and concentrations of draw solution. The FO system using 4 M NH4HCO3 as a draw solution achieved 85% water recovery from OSPW, and 80 to 100% contaminant rejection for most metals and ions. A water backwash cleaning method was applied to clean the fouled membrane, and the cleaned membrane achieved 77% water recovery, a performance comparable to that of new FO membranes. This suggests that the membrane fouling was reversible. The FO system developed in this project provides a novel and energy efficient strategy to remediate the tailings waters generated by oil sands bitumen extraction and processing.

  16. RF Performance of Membrane Aperture Shells

    NASA Technical Reports Server (NTRS)

    Flint, Eirc M.; Lindler, Jason E.; Thomas, David L.; Romanofsky, Robert

    2007-01-01

    This paper provides an overview of recent results establishing the suitability of Membrane Aperture Shell Technology (MAST) for Radio Frequency (RF) applications. These single surface shells are capable of maintaining their figure with no preload or pressurization and minimal boundary support, yet can be compactly roll stowed and passively self deploy. As such, they are a promising technology for enabling a future generation of RF apertures. In this paper, we review recent experimental and numerical results quantifying suitable RF performance. It is shown that candidate materials possess metallic coatings with sufficiently low surface roughness and that these materials can be efficiently fabricated into RF relevant doubly curved shapes. A numerical justification for using a reflectivity metric, as opposed to the more standard RF designer metric of skin depth, is presented and the resulting ability to use relatively thin coating thickness is experimentally validated with material sample tests. The validity of these independent film sample measurements are then confirmed through experimental results measuring RF performance for reasonable sized doubly curved apertures. Currently available best results are 22 dBi gain at 3 GHz (S-Band) for a 0.5m aperture tested in prime focus mode, 28dBi gain for the same antenna in the C-Band (4 to 6 GHz), and 36.8dBi for a smaller 0.25m antenna tested at 32 GHz in the Ka-Band. RF range test results for a segmented aperture (one possible scaling approach) are shown as well. Measured antenna system actual efficiencies (relative to the unachievable) ideal for these on axis tests are generally quite good, typically ranging from 50 to 90%.

  17. Microsequence analysis of electroblotted proteins. II. Comparison of sequence performance on different types of PVDF membranes.

    PubMed

    Reim, D F; Speicher, D W

    1992-11-15

    The influence of different types of polyvinylidene difluoride (PVDF) membranes on gas phase sequence performance has been evaluated. These PVDF membranes have been classified as either high retention (Trans-Blot and ProBlott) or low retention membranes (Immobilon-P) based on their ability to bind proteins during electroblotting from gels. Initial yields, repetitive yields, and extraction efficiency of the anilinothiazolinone amino acid derivatives have been compared for several standard proteins that have been either electroblotted or loaded onto PVDF membranes by direct adsorption. These results show that the major differences in initial sequence yields between membranes arise from differences in the amount of protein actually transferred to the membrane rather than sequencer-related factors. In contrast to several previous observations from other laboratories, more tightly bound proteins do not sequence with lower initial yields and initial yields are not affected by the ratio of surface area to protein. The stronger binding on high retention PVDF membranes does not adversely affect recoveries of difficult to extract, or very hydrophobic, amino acid derivatives. Several amino acids, especially tryptophan, are actually recovered in dramatically higher yield on high retention membranes compared with either Immobilon or glass filters. At the same time, the protein and peptide binding properties of high retention membranes will frequently improve the repetitive yield by minimizing sample extraction during the sequencer cycle. Stronger protein binding together with improved electroblotting yields offer substantially improved sequence performance when high retention PVDF membranes are used.

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

    PubMed

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

    2010-05-15

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

  19. Phosphoric acid distribution and its impact on the performance of polybenzimidazole membranes

    NASA Astrophysics Data System (ADS)

    Mack, Florian; Heissler, Stefan; Laukenmann, Ruben; Zeis, Roswitha

    2014-12-01

    Phosphoric acid doped polybenzimidazole (PBI) is the most common membrane material for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC). The PBI membrane is usually doped by immersion in hot phosphoric acid. Immersion time and acid temperature affect the doping level of the membrane. In this work we studied the influence of doping time and temperature on the ex-situ and in-situ proton conductivities of poly (2, 5-benzimidazole) (AB-PBI) membranes as well as the fuel cell performance. Confocal Raman microscopy was employed to spatially resolve the acid distribution within the AB-PBI membranes. Therefore the interactions between the basic nitrogen-sides of the AB-PBI polymer and the phosphoric acid protons were investigated. We found that membranes with a 6 h doping time had significantly higher proton conductivity than those doped for only 3 h. In terms of absolute acid up-take, however, the difference was rather small. This result shows that the doping level alone does not define the conductivity of the membrane. The conductivity is also influenced by the micro acid distribution within the membrane. Highest membrane conductivity and fuel cell performance with fumapem AM cross-linked membranes were achieved with a doping time of 6 h and a doping temperature of 120 °C.

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

    NASA Astrophysics Data System (ADS)

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

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

  1. Biofouling behavior and performance of forward osmosis membranes with bioinspired surface modification in osmotic membrane bioreactor.

    PubMed

    Li, Fang; Cheng, Qianxun; Tian, Qing; Yang, Bo; Chen, Qianyuan

    2016-07-01

    Forward osmosis (FO) has received considerable interest for water and energy related applications in recent years. Biofouling behavior and performance of cellulose triacetate (CTA) forward osmosis membranes with bioinspired surface modification via polydopamine (PD) coating and poly (ethylene glycol) (PEG) grafting (PD-g-PEG) in a submerged osmotic membrane bioreactor (OMBR) were investigated in this work. The modified membranes exhibited lower flux decline than the pristine one in OMBR, confirming that the bioinspired surface modification improved the antifouling ability of the CTA FO membrane. The result showed that the decline of membrane flux related to the increase of the salinity and MLSS concentration of the mixed liquid. It was concluded that the antifouling ability of modified membranes ascribed to the change of surface morphology in addition to the improvement of membrane hydrophilicity. The bioinspired surface modifications might improve the anti-adhesion for the biopolymers and biocake.

  2. Effect of membrane character and solution chemistry on microfiltration performance.

    PubMed

    Gray, S R; Ritchie, C B; Tran, T; Bolto, B A; Greenwood, P; Busetti, F; Allpike, B

    2008-02-01

    To help understand and predict the role of natural organic matter (NOM) in the fouling of low-pressure membranes, experiments were carried out with an apparatus that incorporates automatic backwashing and long filtration runs. Three hollow fibre membranes of varying character were included in the study, and the filtration of two different surface waters was compared. The hydrophilic membrane had greater flux recovery after backwashing than the hydrophobic membranes, but the efficiency of backwashing decreased at extended filtration times. NOM concentration of these waters (7.9 and 9.1mg/L) had little effect on the flux of the membranes at extended filtration times, as backwashing of the membrane restored the flux to similar values regardless of the NOM concentration. The solution pH also had little effect at extended filtration times. The backwashing efficiency of the hydrophilic membrane was dramatically different for the two waters, and the presence of colloid NOM alone could not explain these differences. It is proposed that colloidal NOM forms a filter cake on the surface of the membranes and that small molecular weight organics that have an adsorption peak at 220nm but not 254nm were responsible for "gluing" the colloids to the membrane surface. Alum coagulation improved membrane performance in all instances, and this was suggested to be because coagulation reduced the concentration of "glue" that holds the organic colloids to the membrane surface.

  3. Spatial proton exchange membrane fuel cell performance under bromomethane poisoning

    NASA Astrophysics Data System (ADS)

    Reshetenko, Tatyana V.; Artyushkova, Kateryna; St-Pierre, Jean

    2017-02-01

    The poisoning effects of 5 ppm CH3Br in the air on the spatial performance of a proton exchange membrane fuel cell (PEMFC) were studied using a segmented cell system. The presence of CH3Br caused performance loss from 0.650 to 0.335 V at 1 A cm-2 accompanied by local current density redistribution. The observed behavior was explained by possible bromomethane hydrolysis with the formation of Br-. Bromide and bromomethane negatively affected the oxygen reduction efficiency over a wide range of potentials because of their adsorption on Pt, which was confirmed by XPS. Moreover, the PEMFC exposure to CH3Br led to a decrease in the anode and cathode electrochemical surface area (∼52-57%) due to the growth of Pt particles through agglomeration and Ostwald ripening. The PEMFC did not restore its performance after stopping bromomethane introduction to the air stream. However, the H2/N2 purge of the anode/cathode and CV scans almost completely recovered the cell performance. The observed final loss of ∼50 mV was due to an increased activation overpotential. PEMFC exposure to CH3Br should be limited to concentrations much less than 5 ppm due to serious performance loss and lack of self-recovery.

  4. Factors affecting plant growth in membrane nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Wheeler, R. M.; Sager, J. C.; Knott, W. M.

    1990-01-01

    The development of the tubular membrane plant growth unit for the delivery of water and nutrients to roots in microgravity has recently focused on measuring the effects of changes in physical variables controlling solution availability to the plants. Significant effects of membrane pore size and the negative pressure used to contain the solution were demonstrated. Generally, wheat grew better in units with a larger pore size but equal negative pressure and in units with the same pore size but less negative pressure. Lettuce also exhibited better plant growth at less negative pressure.

  5. Performance of PDMS membranes in pervaporation: effect of silicalite fillers and comparison with SBS membranes.

    PubMed

    Dobrak, A; Figoli, A; Chovau, S; Galiano, F; Simone, S; Vankelecom, I F J; Drioli, E; Van der Bruggen, B

    2010-06-01

    Laboratory-made silicalite filled PDMS membranes were tested by means of concentration and temperature influence on the membrane performance in removal of ethanol from ethanol/water mixtures. This allowed studying the applicability of solution-diffusion model in the transport mechanism description. Experiments were performed by varying the ethanol concentration in the feed and temperature. Two types of fillers were incorporated into the PDMS network: commercial zeolite silicalite (CBV 3002) and laboratory-made colloidal silicalite-1. Obtained results were then compared with data gathered for unfilled PDMS membranes to examine the effect of fillers incorporation. Moreover, the comparison with novel block co-polymer based porous and dense SBS membranes was done. It was found that the solution-diffusion model was a good representation of ethanol transport through both filled and unfilled PDMS membranes, whereas the water flux did not obey this model due to the swelling effects. Incorporation of the fillers increased membrane stability and improved the selectivity. Performance of the SBS membranes characterized by a dense structure was found to be similar to the performance of filled PDMS membranes.

  6. Securin and separase modulate membrane traffic by affecting endosomal acidification.

    PubMed

    Bacac, Marina; Fusco, Carlo; Planche, Anne; Santodomingo, Jaime; Demaurex, Nicolas; Leemann-Zakaryan, Ruzanna; Provero, Paolo; Stamenkovic, Ivan

    2011-05-01

    Securin and separase play a key role in sister chromatid separation during anaphase. However, a growing body of evidence suggests that in addition to regulating chromosome segregation, securin and separase display functions implicated in membrane traffic in Caenorhabditis elegans and Drosophila. Here we show that in mammalian cells both securin and separase associate with membranes and that depletion of either protein causes robust swelling of the trans-Golgi network (TGN) along with the appearance of large endocytic vesicles in the perinuclear region. These changes are accompanied by diminished constitutive protein secretion as well as impaired receptor recycling and degradation. Unexpectedly, cells depleted of securin or separase display defective acidification of early endosomes and increased membrane recruitment of vacuolar (V-) ATPase complexes, mimicking the effect of the specific V-ATPase inhibitor Bafilomycin A1. Taken together, our findings identify a new functional role of securin and separase in the modulation of membrane traffic and protein secretion that implicates regulation of V-ATPase assembly and function.

  7. Effect of membrane characteristics on the performance of membrane bioreactors for oily wastewater treatment.

    PubMed

    Mafirad, S; Mehrnia, M R; Sarrafzadeh, M H

    2011-01-01

    Influence of membrane material and pore size on the performance of a submerged membrane bioreactor (sMBR) for oily wastewater treatment was investigated. The sMBR had a working volume of about 19 L with flat sheet modules at the same hydrodynamic conditions. Five types of micro- and ultra-polymeric membranes containing cellulose acetate (CA), cellulose nitrate (CN), polyamide (PA), polyvinylidene difluoride (PVDF) and polyethersulfone (PES) were used and their filtration performance in terms of permeability, permeate quality and fouling intensity were evaluated. Characterization of the membranes was done by performing some analysis such as pore size distribution; contact angle and scanning electronic microscopy (SEM) microphotograph on all membranes. The quality of permeates from each membrane was identified by measuring chemical oxygen demand (COD). The results showed more irreversible fouling intensity for membranes with larger pore size which can be due to more permeation of bioparticles and colloids inside the pores. Membrane characteristics have a major role in the preliminary time of the filtration before cake layer formation so that the PA with the highest hydrophilicity had the lowest permeability decline by fouling in this period. Also, the PVDF and PES membranes had better performance according to better permeate quality in the preliminary time of the filtration related to smaller pore size and also their better fouling resistance and chemical stability properties. However, all membranes resulted in the same permeability and permeate quality after cake layer formation. An overall efficiency of about 95% in COD removal was obtained for oily wastewater treatment by the membranes used in this study.

  8. Effects of transmembrane hydraulic pressure on performance of forward osmosis membranes.

    PubMed

    Coday, Bryan D; Heil, Dean M; Xu, Pei; Cath, Tzahi Y

    2013-03-05

    Forward osmosis (FO) is an emerging membrane separation process that continues to be tested and implemented in various industrial water and wastewater treatment applications. The growing interests in the technology have prompted laboratories and manufacturers to adopt standard testing methods to ensure accurate comparison of membrane performance under laboratory-controlled conditions; however, standardized methods might not capture specific operating conditions unique to industrial applications. Experiments with cellulose triacetate (CTA) and polyamide thin-film composite (TFC) FO membranes demonstrated that hydraulic transmembrane pressure (TMP), common in industrial operation of FO membrane elements, could affect membrane performance. Experiments were conducted with three FO membranes and with increasing TMP up to a maximum of 50 psi (3.45 bar). The feed solution was a mixture of salts and the draw solution was either a NaCl solution or concentrated seawater at similar osmotic pressure. Results revealed that TMP minimally affected water flux, reverse salt flux (RSF), and solute rejection of the CTA membrane. However, water flux through TFC membranes might slightly increase with increasing TMP, and RSF substantially declines with increasing TMP. It was observed that rejection of feed constituents was influenced by TMP and RSF.

  9. Insights into the Impact of the Nafion Membrane Pretreatment Process on Vanadium Flow Battery Performance.

    PubMed

    Jiang, Bo; Yu, Lihong; Wu, Lantao; Mu, Di; Liu, Le; Xi, Jingyu; Qiu, Xinping

    2016-05-18

    Nafion membranes are now the most widely used membranes for long-life vanadium flow batteries (VFBs) because of their extremely high chemical stability. Today, the type of Nafion membrane that should be selected and how to pretreat these Nafion membranes have become critical issues, which directly affects the performance and cost of VFBs. In this work, we chose the Nafion 115 membrane to investigate the effect of the pretreatment process (as received, wet, boiled, and boiled and dried) on the performance of VFBs. The relationship between the nanostructure and transport properties of Nafion 115 membranes is elucidated by wide-angle X-ray diffraction and small-angle X-ray scattering techniques. The self-discharge process, battery efficiencies, electrolyte utilization, and long-term cycling stability of VFBs with differently pretreated Nafion membranes are presented comprehensively. An online monitoring system is used to monitor the electrolyte volume that varies during the long-term charge-discharge test of VFBs. The capacity fading mechanism and electrolyte imbalance of VFBs with these Nafion 115 membranes are also discussed in detail. The optimal pretreatment processes for the benchmark membrane and practical application are synthetically selected.

  10. Fabrication and performance of PET mesh enhanced cellulose acetate membranes for forward osmosis.

    PubMed

    Li, Guoliang; Wang, Jun; Hou, Deyin; Bai, Yu; Liu, Huijuan

    2016-07-01

    Polyethylene terephthalate mesh (PET) enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis (FO) mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2μm. The performance of the optimal FO membrane was tested using 0.2mol/L NaCl as the feed solution and 1.5mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47L/(m(2)·hr) and salt rejection of 95.48% in FO mode. While in pressure retarded osmosis (PRO) mode, the water flux was 4.74L/(m(2)·hr) and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes.

  11. Modeling the effect of membrane conductivity on the performance of alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Raya, Isaac P.; Ellis, Michael W.; Hernandez-Guerrero, Abel; Elizalde-Blancas, Francisco

    2016-03-01

    The present work proposes and demonstrates a methodology to capture the effect of operating conditions on ionic conductivity of membranes immersed in alkaline media. Based on reported experimental results for an anion exchange membrane (A-201 by Tokuyama) and a cation exchange membrane (Nafion 211), two novel expressions are developed for the ionic conductivity by incorporating the effects of solution concentration and temperature. The expression for the cationic conductivity is applied in a cell-level model to predict the performance of an alkaline direct borohydride fuel cell; it is found that the membrane ionic conductivity significantly affects the cell performance and capturing its functionality is essential to accurately predict the fuel cell performance.

  12. Yeast mutants affecting possible quality control of plasma membrane proteins.

    PubMed

    Li, Y; Kane, T; Tipper, C; Spatrick, P; Jenness, D D

    1999-05-01

    Mutations gef1, stp22, STP26, and STP27 in Saccharomyces cerevisiae were identified as suppressors of the temperature-sensitive alpha-factor receptor (mutation ste2-3) and arginine permease (mutation can1(ts)). These suppressors inhibited the elimination of misfolded receptors (synthesized at 34 degrees C) as well as damaged surface receptors (shifted from 22 to 34 degrees C). The stp22 mutation (allelic to vps23 [M. Babst and S. Emr, personal communication] and the STP26 mutation also caused missorting of carboxypeptidase Y, and ste2-3 was suppressed by mutations vps1, vps8, vps10, and vps28 but not by mutation vps3. In the stp22 mutant, both the mutant and the wild-type receptors (tagged with green fluorescent protein [GFP]) accumulated within an endosome-like compartment and were excluded from the vacuole. GFP-tagged Stp22p also accumulated in this compartment. Upon reaching the vacuole, cytoplasmic domains of both mutant and wild-type receptors appeared within the vacuolar lumen. Stp22p and Gef1p are similar to tumor susceptibility protein TSG101 and voltage-gated chloride channel, respectively. These results identify potential elements of plasma membrane quality control and indicate that cytoplasmic domains of membrane proteins are translocated into the vacuolar lumen.

  13. Effects of small halocarbon molecules on reverse osmosis membrane performance

    SciTech Connect

    Cheng, R.C.; Glater, J.; Neethling, J.B. )

    1990-01-01

    The reverse osmosis (RO) membrane industry has long been concerned with problems of performance decline due to fouling. Colloidal and biological fouling have been discussed to some extent in the literature but little is known about the effect of small organic molecules on membrane performance. The work reported in this paper involved controlled laboratory experiments with three small halocarbons and three different types of commercial RO membranes. The compounds used were CHCl{sub 3}, CHBr{sub 3} and CCl{sub 4}. The first two represent typical small and large THM's. Carbon tetrachloride was selected as a non-polar model compound. Membranes representing three different polymer systems were provided by E. I. du Pont Inc.

  14. Attribution, Affect, and College Exam Performance.

    ERIC Educational Resources Information Center

    Arkin, Robert M.; Maruyama, Geoffrey M.

    1979-01-01

    College students attributed their own performance and the performance of the average student to ability, test difficulty, preparation, and luck. Successful students perceived internal factors and unsuccessful students perceived external factors as more important causes of their own performance. Students' anxiety and their ratings of the course and…

  15. Alteration of membrane phospholipid methylation by adenosine analogs does not affect T lymphocyte activation

    SciTech Connect

    Gormand, F.; Pacheco, Y. ); Fonlupt, P. ); Revillard, J.P. )

    1990-01-01

    Membrane phospholipid methylation has been described during activation of various immune cells. Moreover recent data indicated modulation of immune cells functions by adenosine. As S-adenosyl-methionine and S-adenosyl-homocysteine are adenosine analogs and modulators of transmethylation reactions, the effects of SAH and SAM were investigated on membrane phospholipid methylation and lymphocyte activation. SAM was shown to induce the membrane phospholipid methylation as assessed by the {sup 3}Hmethyl-incorporation in membrane extract. This effect was inhibited by SAH. In contrast SAM and SAH did not affect the phytohemagglutinin-induced proliferative response of peripheral blood mononuclear cells. SAH neither modified the early internalization of membrane CD3 antigens nor did it prevent the late expression of HLA-DR antigens on lymphocytes activated by phytohemagglutinin. These results indicate that in vitro alteration of phospholipid methylation does not affect subsequent steps of human T lymphocyte activation and proliferation.

  16. Membrane fluidization triggers membrane remodeling which affects the thermotolerance in Escherichia coli.

    PubMed

    Shigapova, Natalia; Török, Zsolt; Balogh, Gábor; Goloubinoff, Pierre; Vígh, László; Horváth, Ibolya

    2005-03-25

    Treatment of Escherichia coli with non-lethal doses of heat or benzyl alcohol (BA) causes transient membrane fluidization and permeabilization, and induces the rapid transcription of heat-shock genes in a sigma32-dependent manner. This early response is followed by a rapid adaptation (priming) of the cells to otherwise lethal elevated temperature, in strong correlation with an observed remodeling of the composition and alkyl chain unsaturation of membrane lipids. The acquisition of cellular thermotolerance in BA-primed cells is unrelated to protein denaturation and is not accompanied by the formation of major heat-shock proteins, such as GroEL and DnaK. This suggests that the rapid remodeling of membrane composition is sufficient for the short-term bacterial thermotolerance.

  17. Phosphocreatine interacts with phospholipids, affects membrane properties and exerts membrane-protective effects.

    PubMed

    Tokarska-Schlattner, Malgorzata; Epand, Raquel F; Meiler, Flurina; Zandomeneghi, Giorgia; Neumann, Dietbert; Widmer, Hans R; Meier, Beat H; Epand, Richard M; Saks, Valdur; Wallimann, Theo; Schlattner, Uwe

    2012-01-01

    A broad spectrum of beneficial effects has been ascribed to creatine (Cr), phosphocreatine (PCr) and their cyclic analogues cyclo-(cCr) and phospho-cyclocreatine (PcCr). Cr is widely used as nutritional supplement in sports and increasingly also as adjuvant treatment for pathologies such as myopathies and a plethora of neurodegenerative diseases. Additionally, Cr and its cyclic analogues have been proposed for anti-cancer treatment. The mechanisms involved in these pleiotropic effects are still controversial and far from being understood. The reversible conversion of Cr and ATP into PCr and ADP by creatine kinase, generating highly diffusible PCr energy reserves, is certainly an important element. However, some protective effects of Cr and analogues cannot be satisfactorily explained solely by effects on the cellular energy state. Here we used mainly liposome model systems to provide evidence for interaction of PCr and PcCr with different zwitterionic phospholipids by applying four independent, complementary biochemical and biophysical assays: (i) chemical binding assay, (ii) surface plasmon resonance spectroscopy (SPR), (iii) solid-state (31)P-NMR, and (iv) differential scanning calorimetry (DSC). SPR revealed low affinity PCr/phospholipid interaction that additionally induced changes in liposome shape as indicated by NMR and SPR. Additionally, DSC revealed evidence for membrane packing effects by PCr, as seen by altered lipid phase transition. Finally, PCr efficiently protected against membrane permeabilization in two different model systems: liposome-permeabilization by the membrane-active peptide melittin, and erythrocyte hemolysis by the oxidative drug doxorubicin, hypoosmotic stress or the mild detergent saponin. These findings suggest a new molecular basis for non-energy related functions of PCr and its cyclic analogue. PCr/phospholipid interaction and alteration of membrane structure may not only protect cellular membranes against various insults, but could

  18. Long term performance of membranes in an anaerobic membrane bioreactor treating municipal wastewater.

    PubMed

    Dong, Qirong; Parker, Wayne; Dagnew, Martha

    2016-02-01

    The long term impact of SRT (100-40 days) and recovery cleaning on membrane performance of an AnMBR treating authentic municipal wastewater in a large pilot plant was assessed. Successful operation of the pilot plant at a flux of 17 LMH was maintained for a period of 536 days during which the longest period of operation without recovery cleaning or membrane replacement was 178 days. Lower SRT (40 days) reduced the fouling propensity of the mixed liquor in terms of TSS concentration and the dewaterability indicators including colloidal COD (cCOD) concentration and capillary suction time (CST). Critical fluxes ranged from 21 to 23 LMH to 25-27 LMH for SRTs of 70 and 40 days respectively and this was consistent with the reduced concentrations of TSS and improved dewaterability under the latter conditions. Recovery cleaning was found to result in substantial reduction of resistance as indicated by both pilot plant operation and clean water flux tests. The long-term fouling rate was observed to be higher with cleaned membranes as compared to virgin membranes. The lower membrane fouling with virgin membranes suggested that accumulation of foulants, which were resistant to cleaning, caused the higher fouling rates for the cleaned membranes.

  19. Basic investigation into the electrical performance of solid electrolyte membranes

    NASA Technical Reports Server (NTRS)

    Richter, R.

    1982-01-01

    The electrical performance of solid electrolyte membranes was investigated analytically and the results were compared with experimental data. It is concluded that in devices that are used for pumping oxygen the major power losses have to be attributed to the thin film electrodes. Relations were developed by which the effectiveness of tubular solid electrolyte membranes can be determined and the optimum length evaluated. The observed failure of solid electrolyte tube membranes in very localized areas is explained by the highly non-uniform current distribution in the membranes. The analysis points to a possible contact resistance between the electrodes and the solid electrolyte material. This possible contact resistance remains to be investigated experimentally. It is concluded that film electrodes are not appropriate for devices which operate with current flow, i.e., pumps though they can be employed without reservation in devices that measure oxygen pressures if a limited increase in the response time can be tolerated.

  20. The depth of porphyrin in a membrane and the membrane's physical properties affect the photosensitizing efficiency.

    PubMed Central

    Lavi, Adina; Weitman, Hana; Holmes, Robert T; Smith, Kevin M; Ehrenberg, Benjamin

    2002-01-01

    Photosensitized biological processes, as applied in photodynamic therapy, are based on light-triggered generation of molecular singlet oxygen by a membrane-residing sensitizer. Most of the sensitizers currently used are hydrophobic or amphiphilic porphyrins and their analogs. The possible activity of the short-lived singlet oxygen is limited to the time it is diffusing in the membrane, before it emerges into the aqueous environment. In this paper we demonstrate the enhancement of the photosensitization process that is obtained by newly synthesized protoporphyrin derivatives, which insert their tetrapyrrole chromophore deeper into the lipid bilayer of liposomes. The insertion was measured by fluorescence quenching by iodide and the photosensitization efficiency was measured with 9,10-dimethylanthracene, a fluorescent chemical target for singlet oxygen. We also show that when the bilayer undergoes a melting phase transition, or when it is fluidized by benzyl alcohol, the sensitization efficiency decreases because of the enhanced diffusion of singlet oxygen. The addition of cholesterol or of dimyristoyl phosphatydilcholine to the bilayer moves the porphyrin deeper into the bilayer; however, the ensuing effect on the sensitization efficiency is different in these two cases. These results could possibly define an additional criterion for the choice and design of hydrophobic, membrane-bound photosensitizers. PMID:11916866

  1. Factors affecting filtration characteristics in membrane-coupled moving bed biofilm reactor.

    PubMed

    Lee, Woo-Nyoung; Kang, In-Joong; Lee, Chung-Hak

    2006-05-01

    Factors affecting filtration characteristics in submerged hollow fiber membrane were investigated in membrane-coupled moving bed biofilm reactor (M-CMBBR). The trend of membrane biofouling in M-CMBBR was quite different from that in a conventional membrane bioreactor (MBR). The M-CMBBR showed much lower biofouling rate than a conventional MBR. Whereas the membrane biofouling in conventional MBR system is known to be dependent mostly on biochemical effects of mixed liquor (soluble COD, EPS, etc.), the extent of biofouling in M-CMBBR was largely dependent on the potential collision energy of biofilm carriers (media) moving freely and colliding with surfaces of submerged hollow fibers. The collisions between circulating media and hollow fiber membranes gave rise to frictional forces which mitigated the formation of biofilms on the outer surface of hollow fibers. Consequently, the membrane permeability was greatly enhanced. The potential collision energy of moving media was dependent on the media volume fraction as well as the air flow rate. The membrane permeability was found to be proportional to the relative potential collision energy of the biofilm carriers. The frictional effect on the morphology of biofilms formed on the surface of organic membrane under various operating condition was also examined and identified through their visualization with SEM and AFM.

  2. Critical process parameters affecting zincrometal performance

    SciTech Connect

    Iezzi, R.A.

    1984-01-01

    A laboratory study aimed at improving the corrosion resistance of Zincrometal has shown that excellent Zincrometal performance in laboratory corrosion tests can be obtained by achieving a trivalent (Cr+3) to hexavalent (Cr+6) Dacromet chromium ratio of at least 15. Increasing thermal energy input during curing increases the Cr+3/Cr+6 ratio and improves corrosion resistance in laboratory tests. Increasing curing energy input in production may be a viable approach to improve Zincrometal performance, provided that steels not susceptible to strain aging are used.

  3. Factors Affecting Information Literacy Perception and Performance

    ERIC Educational Resources Information Center

    Zehner, Drusilla Charlene Beecher

    2009-01-01

    Information literacy, defined as, "the set of skills needed to find, retrieve, analyze, and use information" (American Library Association, 2003, paragraph 1), is necessary for success in life. The present study will examine whether the factors of gender, race, and/or socioeconomic status impact information literacy performance and…

  4. Lipid composition affects the rate of photosensitized dissipation of cross-membrane diffusion potential on liposomes

    PubMed Central

    Ytzhak, Shany; Wuskell, Joseph P.; Loew, Leslie M.; Ehrenberg, Benjamin

    2010-01-01

    Hydrophobic or amphiphilic tetrapyrrole sensitizers are taken up by cells and are usually located in cellular lipid membranes. Singlet oxygen is photogenerated by the sensitizer and it diffuses in the membrane and causes oxidative damage to membrane components. This damage can occur to membrane lipids and to membrane-localized proteins. Depolarization of the Nernst electric potential on cells’ membranes has been observed in cellular photosensitization, but it was not established whether lipid oxidation is a relevant factor leading to abolishing the resting potential of cells’ membranes and to their death. In this work we studied the effect of liposomes’ lipid composition on the kinetics of hematoporphyrin-photosensitized dissipation of K+-diffusion electric potential that was generated across the membranes. We employed an electrochromic voltage-sensitive spectroscopic probe that possesses a high fluorescence signal response to the potential. We found a correlation between the structure and unsaturation of lipids and the leakage of the membrane, following photosensitization. As the extent of non-conjugated unsaturation of the lipids is increased from 1 to 6 double bonds, the kinetics of depolarization become faster. We also found that the kinetics of depolarization is affected by the percentage of the unsaturated lipids in the liposome: as the fraction of the unsaturated lipids increases the leakage trough the membrane is enhanced. When liposomes are composed of a lipid mixture similar to that of natural membranes and photosensitization is being carried out under usual photodynamic therapy (PDT) conditions, photodamage to the lipids is not likely to cause enhanced permeability of ions through the membrane, which would have been a mechanism that leads to cell death. PMID:20536150

  5. Upgrading natural gas by means of highly performing polyimide membranes

    SciTech Connect

    Stern, S.A.

    1993-12-31

    The objective of the present research project is to assess the potential usefulness of membrane separation processes for the removal of acid gases (CO{sub 2} and H{sub 2}S) and H{sub 2}O vapor from low-quality natural gas. The following tasks were performed during the last two years of the project: (1) A laboratory-scale apparatus for measuring the permeability and selectivity of polymer membranes to gas mixtures was built and tested. (2) The permeability and selectivity of seven new polyamide membranes to binary CH{sub 4}/CO{sub 2} and ternary CH{sub 4}/CO{sub 2}/H{sub 2}S mixtures were measured at 95{degrees}F (35{degrees}C) and at ``upstream`` pressures in the range from 58.8 psia to 200 psia (4 atm to 13.6 atm). (3) Gas separation measurements were made using binary CH{sub 4}/CO{sub 2} and ternary CH{sub 4}/CO{sub 2}/H{sub 2}S feed gas mixtures. (4) Process design studies and economic evaluations of membrane processes for upgrading low-quality natural gas were made using the experimentally obtained permeability and selectivity values for the three most promising polyamide membranes. For the sake of comparison, similar studies were made also for cellulose acetate membranes, which are at present being widely used on an industrial scale for the separation of CO{sub 2} from natural gas.

  6. Factors affecting penetrating captive bolt gun performance.

    PubMed

    Gibson, Troy J; Mason, Charles W; Spence, Jade Y; Barker, Heather; Gregory, Neville G

    2015-01-01

    Captive bolt stunning is used for rendering livestock insensible at slaughter. The mechanical factors relating to performance of 6 penetrating captive bolt gun (CBG) models were examined. The Matador Super Sécurit 3000 and the .25 Cash Euro Stunner had the highest kinetic energy values (443 J and 412 J, respectively) of the CBGs tested. Ninety percent (27/30) of CBGs held at a government gun repository (United Kingdom) were found to have performed at a normal standard for the model, while 53% (10/19) of commercial contractor CBGs tested were found to underperform for the gun model. When the .22 Cash Special was fired 500 times at 4 shots per min, the gun reached a peak temperature of 88.8°C after 2.05 hr. Repeat firing during extended periods significantly reduced the performance of the CBG. When deciding on the appropriate CBG/cartridge combination, the kinetic energy delivered to the head of the nonhuman animal, bolt penetration depth, and species/animal type must be considered. It is recommended that CBGs are routinely checked for wear to the bolt and barrel if they are repeatedly fired in a session.

  7. Does posttraumatic stress disorder (PTSD) affect performance?

    PubMed

    LeBlanc, Vicki R; Regehr, Cheryl; Jelley, R Blake; Barath, Irene

    2007-08-01

    Research has increasingly identified alarming levels of traumatic stress symptoms in individuals working in emergency services and other high stress jobs. This study examined the effects of prior critical incident exposure and current posttraumatic symptoms on the performance of a nonpatient population, police recruits, during an acutely stressful event. A stressful policing situation was created through the use of a video simulator room that was responsive to actions of participants. The performance of participants to the simulated emergency was evaluated by 3 independent blinded raters. Prior exposure to critical incidents was measured using the Critical Incident History Questionnaire and current level of traumatic stress symptoms was measured using the Impact of Events Scale-Revised. Neither previous exposure to critical incidents nor trauma symptoms correlated with performance level. Recruits with high or severe levels of trauma symptoms did not demonstrate impairments in judgment, communication, or situation control compared with their colleagues with lesser or no trauma symptoms. On the basis of these findings, there is no reason to believe that police recruits with PTSD are prone to making errors of communication or judgment that would place them or others at increased risk.

  8. Performance of porous inorganic membranes in non-osmotic desalination.

    PubMed

    Duke, M C; Mee, S; da Costa, J C Diniz

    2007-09-01

    The supply security of fresh drinking water is decreasing and raising a critical situation for communities worldwide. Inorganic membranes such as alumina and molecular sieve silica have in the past been shown to be highly effective at separating gases and could offer promise as liquid separators due to their high flux and stability. In this work, we develop a range of inorganic membranes with pore size ranging from 0.3 to 500nm and relate this to separation and transport performance. Best separation results were achieved for the silica membrane pressurised to only 7bar, exhibiting a flux of around 1.8kgm(-2)h(-1) and NaCl rejection of 98% with 3.5wt% (seawater-like) feed. Potable water from seawater-like feed was achieved from the membrane in a single stage after regeneration. Conditions such as pressure and temperature were also modified showing performance characteristics and diffusion mechanisms. The non-osmotic set-up for inorganic membranes is therefore a viable technology for desalination.

  9. Body position affects performance in untrained cyclists

    PubMed Central

    Ashe, M; Scroop, G; Frisken, P; Amery, C; Wilkins, M; Khan, K

    2003-01-01

    Objective: To compare cardiovascular and ventilatory variables in upright versus aero cycle ergometry at submaximal and maximal exercise intensities in untrained cyclists. Method: Ten physically active men (mean (SD) age 19.1 (1.10) years) who were unfamiliar with aerobars underwent maximal exercise testing and steady state cycling at 50, 100, and 150 W. Results: Participants had significantly greater maxima for oxygen uptake (VO2), ventilation, heart rate, and workload maximum in the upright position. During steady state cycling at the three workloads, VO2 (ml/kg/min) and gross mechanical efficiency were significantly greater in the upright position. Conclusions: In untrained subjects performing with maximal effort, the upright position permits greater VO2, ventilation, heart rate, and workload maxima. Further, in the steady state, exercise cycling may be less costly in the upright position. For this reason, untrained cyclists need to weigh body position effects against the well known aerodynamic advantages of the aero position. PMID:14514538

  10. Novel nanocomposite Kevlar fabric membranes: Fabrication characterization, and performance in oil/water separation

    NASA Astrophysics Data System (ADS)

    Karimnezhad, Hanieh; Rajabi, Laleh; Salehi, Ehsan; Derakhshan, Ali Ashraf; Azimi, Sara

    2014-02-01

    Nanocomposite membranes with hydrophilic surface were fabricated for separation of oil (n-hexane) from oil/water emulsion. Three different nanomaterials namely, para-aminobenzoate alumoxane (PAB-A), boehmite-epoxide and polycitrate alumoxane (PC-A) were coated on the Kevlar fabric (support), according to a three-step dip-coating protocol. FTIR, SEM, TEM, UV/vis spectrophotometer, and wettability analyses were used to characterize the composite membranes. The three coating layers interacted chemically with one another and also physically with the Kevlar fabric. Water uptake measurements indicated that the membrane is a hydrophilic one. SEM and TEM analyses showed the smooth surface of the composite membrane and three-dimensional dendrimeric hyper-branched structure of (PC-A), respectively. A dead-end filtration setup was applied to test the membranes performance under natural gravity force. Effect of pH as an important variable affecting separation process was investigated with the neutral pH provided the optimum condition for the separation. Oil rejection and permeate fluxes were also monitored. The optimum flux and rejection obtained, were 7392 (Lm-2 h-1) and 89.06% at pH 7, respectively. Fouling occurred as a gel layer on the membrane surface. The deposited oil droplets on the surface of the membrane were successfully washed away with satisfactory permeate flux recovery (FRR = 88.88% at neutral pH), using hot distilled water and acidic solution as eluents.

  11. Microstructured Electrolyte Membranes to Improve Fuel Cell Performance

    NASA Astrophysics Data System (ADS)

    Wei, Xue

    Fuel cells, with the advantages of high efficiency, low greenhouse gas emission, and long lifetime are a promising technology for both portable power and stationary power sources. The development of efficient electrolyte membranes with high ionic conductivity, good mechanical durability and dense structure at low cost remains a challenge to the commercialization of fuel cells. This thesis focuses on exploring novel composite polymer membranes and ceramic electrolytes with the microstructure engineered to improve performance in direct methanol fuel cells (DMFCs) and solid oxide fuel cells (SOFCs), respectively. Polymer/particle composite membranes hold promise to meet the demands of DMFCs at lower cost. The structure of composite membranes was controlled by aligning proton conducting particles across the membrane thickness under an applied electric field. The field-induced structural changes caused the membranes to display an enhanced water uptake, proton conductivity, and methanol permeability in comparison to membranes prepared without an applied field. Although both methanol permeability and proton conductivity are enhanced by the applied field, the permeability increase is relatively lower than the proton conductivity improvement, which results in enhanced proton/methanol selectivity and improved DMFC performance. Apatite ceramics are a new class of fast ion conductors being studied as alternative SOFC electrolytes in the intermediate temperature range. An electrochemical/hydrothermal deposition method was developed to grow fully dense apatite membranes containing well-developed crystals with c-axis alignment to promote ion conductivity. Hydroxyapatite seed crystals were first deposited onto a metal substrate electrochemically. Subsequent ion substitution during the hydrothermal growth process promoted the formation of dense, fully crystalline films with microstructure optimal for ion transport. The deposition parameters were systematically investigated, such as

  12. Alcohol/ether separation by pervaporation. High performance membrane design

    SciTech Connect

    Roizard, D.; Jonquieres, A.; Leger, C.

    1999-02-01

    Several routes were investigated to design high performance membranes for the separation of tert-butyl ethers (octane enhancers) from alcohols by pervaporation. These routes aim at incorporating Lewis base groups into good film-forming polymers with different structures. The Lewis base groups showed a high affinity to alcohols in screening tests, thus imparting high pervaporation selectivity to the polymer materials. They led to several membranes able to extract pure ethanol out of the azeotropic mixture, but with very low permeation rates. Further modifications of the polymer structure allowed the authors to synthesize materials with greatly enhanced transfer rates and with acceptable selectivity for industrial applications. Structure-property relationships were derived from sorption and pervaporation data for a qualitative prediction of the effect of polymer structure on the flux and selectivity. For these solvent-polymer systems the diffusion phenomenon appears to further improve the pervaporation selectivity for alcohol compared with that given by the sorption process at the membrane face.

  13. Temperature effect on transport performance by inorganic nanofiltration membranes

    SciTech Connect

    Tsuru, Toshinori; Izumi, Shuhei; Yoshioka, Tomohisa; Asaeda, Masashi

    2000-03-01

    The effect of temperature on nanofiltration performance was examined using three inorganic membranes with a molecular-weight cutoff of approximately 200, 600, and 2,000, respectively. The inorganic porous membranes were prepared from silica-zirconia colloidal sols and used in nanofiltration experiments for neutral solutes over a temperature range of 20 to 60 C. The rejection of solutes decreased with an increase in temperature for the membranes, while the permeate volume flux increased. Three transport coefficients--reflection coefficient, solute permeability, and water permeability--were obtained using the Spiegler-Kedem equation, which accounts for the contribution of convection and diffusion to solute flux. As a result, the reflection coefficient corresponding to the fraction of solutes reflected by the membrane in convective flow was almost constant, irrespective of experimental temperature. The dependency was larger for larger solutes and membranes with smaller pore diameters. Therefore, the hindered diffusion of solutes through micropores was indicative of an activated process. Moreover, pure water permeability, after correction for the temperature effect on viscosity, also increased with experimental temperature.

  14. Improvement of Membrane Performances to Enhance the Yield of Vanillin in a Pervaporation Reactor

    PubMed Central

    Camera-Roda, Giovanni; Cardillo, Antonio; Loddo, Vittorio; Palmisano, Leonardo; Parrino, Francesco

    2014-01-01

    In membrane reactors, the interaction of reaction and membrane separation can be exploited to achieve a “process intensification”, a key objective of sustainable development. In the present work, the properties that the membrane must have to obtain this result in a pervaporation reactor are analyzed and discussed. Then, the methods to enhance these properties are investigated for the photocatalytic synthesis of vanillin, which represents a case where the recovery from the reactor of vanillin by means of pervaporation while it is produced allows a substantial improvement of the yield, since its further oxidation is thus prevented. To this end, the phenomena that control the permeation of both vanillin and the reactant (ferulic acid) are analyzed, since they ultimately affect the performances of the membrane reactor. The results show that diffusion of the aromatic compounds takes place in the presence of low concentration gradients, so that the process is controlled by other phenomena, in particular by the equilibrium with the vapor at the membrane-permeate interface. On this basis, it is demonstrated that the performances are enhanced by increasing the membrane thickness and/or the temperature, whereas the pH begins to limit the process only at values higher than 6.5. PMID:24957123

  15. Improvement of membrane performances to enhance the yield of vanillin in a pervaporation reactor.

    PubMed

    Camera-Roda, Giovanni; Cardillo, Antonio; Loddo, Vittorio; Palmisano, Leonardo; Parrino, Francesco

    2014-02-28

    In membrane reactors, the interaction of reaction and membrane separation can be exploited to achieve a "process intensification", a key objective of sustainable development. In the present work, the properties that the membrane must have to obtain this result in a pervaporation reactor are analyzed and discussed. Then, the methods to enhance these properties are investigated for the photocatalytic synthesis of vanillin, which represents a case where the recovery from the reactor of vanillin by means of pervaporation while it is produced allows a substantial improvement of the yield, since its further oxidation is thus prevented. To this end, the phenomena that control the permeation of both vanillin and the reactant (ferulic acid) are analyzed, since they ultimately affect the performances of the membrane reactor. The results show that diffusion of the aromatic compounds takes place in the presence of low concentration gradients, so that the process is controlled by other phenomena, in particular by the equilibrium with the vapor at the membrane-permeate interface. On this basis, it is demonstrated that the performances are enhanced by increasing the membrane thickness and/or the temperature, whereas the pH begins to limit the process only at values higher than 6.5.

  16. Proton electrolyte membrane properties and direct methanol fuel cell performance. II. Fuel cell performance and membrane properties effects

    NASA Astrophysics Data System (ADS)

    Silva, V. S.; Schirmer, J.; Reissner, R.; Ruffmann, B.; Silva, H.; Mendes, A.; Madeira, L. M.; Nunes, S. P.

    In order to study the relationship between the properties of proton electrolyte membranes (PEMs), obtained through standard characterization methods, and the direct methanol fuel cell (DMFC) performance, inorganic-organic hybrid membranes, modified via in situ hydrolysis, were used in a membrane electrolyte assembly (MEA) for DMFC application. The membranes, the characterization of which was performed in the previous paper of this series, were based on sulfonated poly(ether ether ketone) (sPEEK) with a sulfonation degree (SD) of 87% and were loaded with different amounts of zirconium oxide (5.0, 7.5, 10.0, 12.5 wt.%). The standard characterization methods applied were impedance spectroscopy (proton conductivity), water uptake, and pervaporation (permeability to methanol). The MEAs were characterized investigating the DMFC current-voltage polarization curves, constant voltage current (CV, 35 mV), and open-circuit voltage (OCV). The fuel cell ohmic resistance (null phase angle impedance, NPAI) and CO 2 concentration in the cathode outlet were also measured. The characterization results show that the incorporation of the inorganic oxide in the polymer network decreases the DMFC current density for CV experiments, CO 2 concentration in the cathode outlet for both OCV and CV experiments and, finally, the maximum power density output. The opposite effect was verified in terms of the NPAI (ohmic resistance) for both OCV and CV experiments. A good agreement was found between the studied DMFC performance parameters and the characterization results evaluated by impedance spectroscopy, water uptake and pervaporation experiments.

  17. Engineering the performance of mixed matrix membranes for gas separations

    NASA Astrophysics Data System (ADS)

    Shu, Shu

    Mixed matrix membranes that comprise domains of organic and inorganic components are investigated in this research. Such materials effectively circumvent the polymeric 'upper bound trade-off curve' and show properties highly attractive for industrial gas separations. Nevertheless, lack of intrinsic compatibility between the organic polymers and inorganic fillers poses the biggest challenge to successful fabrication of mixed matrix membranes. Consequently, control of the nanoscale interface between the sieve and polymer has been the key technical challenge to the implementation of composite membrane materials. The overarching goal of this research was to devise and explore approaches to enhance the performance of mixed matrix membranes by properly tailoring the sieve/polymer interface. In an effort to pursue the aforementioned objective, three approaches were developed and inspected: (i) use of silane coupling agents, (ii) hydrophobizing of sieve surface through alcohol etherification reactions, and (iii) a two-step modification sequence involving the use of a Grignard reagent. A comparison was drawn to evaluate these methodologies and the most effective strategy (Grignard treatment) was selected and further investigated. Successful formulation and characterization of mixed matrix membranes constituting zeolite 4A modified via the Grignard treatment are described in detail. Membranes with impressive improvements in gas separation efficiency and mechanical properties were demonstrated. The basis for the improvements in polymer/sieve compatibility enabled by this specific process were proposed and investigated. A key aspect of the present study was illuminating the detailed chemical mechanisms involved in the Grignard modification. Systematic characterization and carefully designed experiments revealed that the formation of distinctive surface structures is essentially a heterogeneous nucleation process, where Mg(OH)2 crystals grow from the nuclei previously extracted

  18. Experimental study on performance of a planar membrane humidifier for a proton exchange membrane fuel cell stack

    NASA Astrophysics Data System (ADS)

    Hwang, Jenn Jiang; Chang, Wei Ru; Kao, Jenn Kun; Wu, Wei

    2012-10-01

    Experiments are conducted to evaluate the performance of a planar membrane humidifier for a PEM fuel cell stack. The humidification performance of the humidifier adopted here includes the dew point approach temperature (DPAT), water recovery ratio (WRR), and water vapor transfer rate (WVTR). Parametric studies involve the dry inlet temperature, the wet inlet dew point, and the flow rate across the humidifier. Results show that increasing the flow rate across the humidifier linearly increases its pressure drop. However, the DPAT increases sharply at high flow rates (>350 SLPM) due to the inadequate WVTR limited by the humidifier size. In addition, increasing the wet inlet dew point reduces the humidification performance by increasing the DPAT and reducing in the WRR. Moreover, an increase in the dry inlet temperature could reduce the DPAT at the low flow rate of 100 SLPM, but does not affect the DPAT at the high flow rate of 450 SLPM. Furthermore, the electrochemical performance of the stack-humidifier assembly is only 10% less than that of the stack tested on a commercial test station. Stability test reveals a satisfactory reliability of the present membrane humidifier as well.

  19. Truncated brush border myosin I affects membrane traffic in polarized epithelial cells.

    PubMed

    Durrbach, A; Raposo, G; Tenza, D; Louvard, D; Coudrier, E

    2000-05-01

    We investigate, in this study, the potential involvement of an acto-myosin-driven mechanism in endocytosis of polarized cells. We observed that depolymerization of actin filaments using latrunculin A decreases the rate of transferrin recycling to the basolateral plasma membrane of Caco-2 cells, and increases its delivery to the apical plasma membrane. To analyze whether a myosin was involved in endocytosis, we produced, in this polarized cell line, truncated, non-functional, brush border, myosin I proteins (BBMI) that we have previously demonstrated to have a dominant negative effect on endocytosis of unpolarized cells. These non-functional proteins affect the rate of transferrin recycling and the rate of transepithelial transport of dipeptidyl-peptidase IV from the basolateral plasma membrane to the apical plasma membrane. They modify the distribution of internalized endocytic tracers in apical multivesicular endosomes that are accessible to fluid phase tracers internalized from apical and basolateral plasma membrane domains. Altogether, these observations suggest that an acto-myosin-driven mechanism is involved in the trafficking of basolaterally internalized molecules to the apical plasma membrane.

  20. α-Synuclein Oligomers Induced by Docosahexaenoic Acid Affect Membrane Integrity

    PubMed Central

    Fecchio, Chiara; De Franceschi, Giorgia; Relini, Annalisa; Greggio, Elisa; Dalla Serra, Mauro; Bubacco, Luigi; Polverino de Laureto, Patrizia

    2013-01-01

    A key feature of Parkinson disease is the aggregation of α-synuclein and its intracellular deposition in fibrillar form. Increasing evidence suggests that the pathogenicity of α-synuclein is correlated with the activity of oligomers formed in the early stages of its aggregation process. Oligomers toxicity seems to be associated with both their ability to bind and affect the integrity of lipid membranes. Previously, we demonstrated that α-synuclein forms oligomeric species in the presence of docosahexaenoic acid and that these species are toxic to cells. Here we studied how interaction of these oligomers with membranes results in cell toxicity, using cellular membrane-mimetic and cell model systems. We found that α-synuclein oligomers are able to interact with large and small unilamellar negatively charged vesicles acquiring an increased amount of α-helical structure, which induces small molecules release. We explored the possibility that oligomers effects on membranes could be due to pore formation, to a detergent-like effect or to fibril growth on the membrane. Our biophysical and cellular findings are consistent with a model where α-synuclein oligomers are embedded into the lipid bilayer causing transient alteration of membrane permeability. PMID:24312431

  1. Deoxygenation affects tyrosine phosphoproteome of red cell membrane from patients with sickle cell disease.

    PubMed

    Siciliano, Angela; Turrini, Franco; Bertoldi, Mariarita; Matte, Alessandro; Pantaleo, Antonella; Olivieri, Oliviero; De Franceschi, Lucia

    2010-04-15

    Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder related to the production of a defective form of hemoglobin, hemoglobin S (HbS). One of the hallmarks of SCD is the presence of dense, dehydrate highly adhesive sickle red blood cells (RBCs) that result from persistent membrane damage associated with HbS polymerization, abnormal activation of membrane cation transports and generation of distorted and rigid red cells with membrane perturbation and cytoskeleton dysfunction. Although modulation of phosphorylation state of the proteins from membrane and cytoskeleton networks has been proposed to participate in red cell homeostasis, much still remains to be investigated in normal and diseased red cells. Here, we report that tyrosine (Tyr-) phosphoproteome of sickle red cells was different from normal controls and was affected by deoxygenation. We found proteins, p55 and band 4.1, from the junctional complex, differently Tyr-phosphorylated in SCD RBCs compared to normal RBCs under normoxia and modulated by deoxygenation, while band 4.2 was similarly Tyr-phosphorylated in both conditions. In SCD RBCs we identified the phosphopeptides for protein 4.1R located in the protein FERM domain (Tyr-13) and for alpha-spectrin located near or in a linker region (Tyr-422 and Tyr-1498) involving protein areas crucial for their functions in the context of red cell membrane properties, suggesting that Tyr-phosphorylation may be part of the events involved in maintaining membrane mechanical stability in SCD red cells.

  2. Performance processes within affect-related performance zones: a multi-modal investigation of golf performance.

    PubMed

    van der Lei, Harry; Tenenbaum, Gershon

    2012-12-01

    Individual affect-related performance zones (IAPZs) method utilizing Kamata et al. (J Sport Exerc Psychol 24:189-208, 2002) probabilistic model of determining the individual zone of optimal functioning was utilized as idiosyncratic affective patterns during golf performance. To do so, three male golfers of a varsity golf team were observed during three rounds of golf competition. The investigation implemented a multi-modal assessment approach in which the probabilistic relationship between affective states and both, performance process and performance outcome, measures were determined. More specifically, introspective (i.e., verbal reports) and objective (heart rate and respiration rate) measures of arousal were incorporated to examine the relationships between arousal states and both, process components (i.e., routine consistency, timing), and outcome scores related to golf performance. Results revealed distinguishable and idiosyncratic IAPZs associated with physiological and introspective measures for each golfer. The associations between the IAPZs and decision-making or swing/stroke execution were strong and unique for each golfer. Results are elaborated using cognitive and affect-related concepts, and applications for practitioners are provided.

  3. Mathematics Anxiety and the Affective Drop in Performance

    ERIC Educational Resources Information Center

    Ashcraft, Mark H.; Moore, Alex M.

    2009-01-01

    The authors provide a brief review of the history and assessment of math anxiety, its relationship to personal and educational consequences, and its important impact on measures of performance. Overall, math anxiety causes an "affective drop," a decline in performance when math is performed under timed, high-stakes conditions, both in laboratory…

  4. Sewage sludge treatment in a thermophilic membrane reactor (TMR): factors affecting foam formation.

    PubMed

    Collivignarelli, Maria Cristina; Castagnola, Federico; Sordi, Marco; Bertanza, Giorgio

    2016-11-04

    Foam formation in the excess sludge treatment facilities of biological wastewater treatment plants (WWTPs) may represent a critical issue as it could lead to several operative problems and reduce the overall plant performance. This trouble also affects a novel technology recently proposed for sludge minimization, the thermophilic membrane reactor (TMR), operating with alternate aeration/non-aeration cycles. This technology, which has proven to be extremely resilient and suitable for treating industrial wastewater of different nature, demonstrated a high potential also as a solution for integrating existing WWTPs, aiming at the "zero sludge production." In this work, an experimental study was conducted with a TMR pilot plant (fed daily with thickened sewage sludge) by adjusting the duration of aeration/non-aeration alternate cycles. Extracellular polymeric substance (EPS) concentration (and its soluble and bound fractions) has been monitored along with foaming power indices. The results highlight that foaming can be correlated to the presence of soluble protein fraction of EPS. Moreover, EPS production seems to be reduced by increasing the duration of the non-aeration cycles: optimal operating conditions resulted 2 h of aeration followed by 6 h of non-aeration. These conditions allow to obtain an EPS concentration of 500 mg L(-1) with respect to 2300 mg L(-1) measured at the beginning of experimental work.

  5. [MORPHOLOGICAL FEATURES OF RAT MUCOUS MEMBRANE OF THE TONGUE EARLY AFFECTED BY ACRYLIC RESIN MONOMER].

    PubMed

    Davydenko, V; Nidzelskiy, M; Starchenko, I; Davydenko, A; Kuznetsov, V

    2016-03-01

    Base materials, made on the basis of various derivatives of acrylic and methacrylic acids, have been widely used in prosthetic dentistry. Free monomer, affecting the tissues of prosthetic bed and the whole body, is always found in dentures. Therefore, study of the effect of acrylic resins' monomer on mucous membrane of the tongue is crucial. Rat tongue is very similar to human tongue, and this fact has become the basis for selecting these animals to be involved into the experiment. The paper presents the findings related to the effect of "Ftoraks" base acrylic resin monomer on the state of rat mucous membrane of the tongue and its regeneration. The microscopy has found that the greatest changes in the mucous membrane of the tongue occur on day 3 and 7 day after applying the monomer and are of erosive and inflammatory nature. Regeneration of tongue epithelium slows down.

  6. Factors that affect the permeability of commercial hollow-fibre membranes in a submerged anaerobic MBR (HF-SAnMBR) system.

    PubMed

    Robles, A; Ruano, M V; Ribes, J; Ferrer, J

    2013-03-01

    A demonstration plant with two commercial HF ultrafiltration membrane modules (PURON(®), Koch Membrane Systems, PUR-PSH31) was operated with urban wastewater. The effect of the main operating variables on membrane performance at sub-critical and supra-critical filtration conditions was tested. The physical operating variables that affected membrane performance most were gas sparging intensity and back-flush (BF) frequency. Indeed, low gas sparging intensities (around 0.23 Nm(3) h(-1) m(-2)) and low BF frequencies (30-s back-flush for every 10 basic filtration-relaxation cycles) were enough to enable membranes to be operated sub-critically even when levels of mixed liquor total solids were high (up to 25 g L(-1)). On the other hand, significant gas sparging intensities and BF frequencies were required in order to maintain long-term operating at supra-critical filtration conditions. After operating for more than two years at sub-critical conditions (transmembrane flux between 9 and 13.3 LMH at gas sparging intensities of around 0.23 Nm(3) h(-1) m(-2) and MLTS levels from around 10-30 g L(-1)) no significant irreversible/irrecoverable fouling problems were detected (membrane permeability remained above 100 LMH bar(-1) and total filtration resistance remained below 10(13) m(-1)), therefore no chemical cleaning was conducted. Membrane performance was similar to the aerobic HF membranes operated in full-scale MBR plants.

  7. Treatment of oil sands process-affected water (OSPW) using a membrane bioreactor with a submerged flat-sheet ceramic microfiltration membrane.

    PubMed

    Xue, Jinkai; Zhang, Yanyan; Liu, Yang; Gamal El-Din, Mohamed

    2016-01-01

    The release of oil sands process-affected water (OSPW) into the environment is a concern because it contains persistent organic pollutants that are toxic to aquatic life. A modified Ludzack-Ettinger membrane bioreactor (MLE-MBR) with a submerged ceramic membrane was continuously operated for 425 days to evaluate its feasibility on OSPW treatment. A stabilized biomass concentration of 3730 mg mixed liquor volatile suspended solids per litre and a naphthenic acid (NA) removal of 24.7% were observed in the reactor after 361 days of operation. Ultra Performance Liquid Chromatography/High Resolution Mass Spectrometry analysis revealed that the removal of individual NA species declined with increased ring numbers. Pyrosequencing analysis revealed that Betaproteobacteria were dominant in sludge samples from the MLE-MBR, with microorganisms such as Rhodocyclales and Sphingobacteriales capable of degrading hydrocarbon and aromatic compounds. During 425 days of continuous operation, no severe membrane fouling was observed as the transmembrane pressure (TMP) of the MLE-MBR never exceeded -20 kPa given that the manufacturer's suggested critical TMP for chemical cleaning is -35 kPa. Our results indicated that the proposed MLE-MBR has a good potential for removing recalcitrant organics in OSPW.

  8. Perfectionism, Performance, and State Positive Affect and Negative Affect after a Classroom Test

    ERIC Educational Resources Information Center

    Flett, Gordon L.; Blankstein, Kirk R.; Hewitt, Paul L.

    2009-01-01

    The current study examined the associations among trait dimensions of perfectionism, test performance, and levels of positive and negative affect after taking a test. A sample of 92 female university students completed the Multidimensional Perfectionism Scale one week prior to an actual class test. Measures of positive affect and negative affect…

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

    PubMed

    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.

  10. Identification of Yeast Genes Involved in K+ Homeostasis: Loss of Membrane Traffic Genes Affects K+ Uptake

    PubMed Central

    Fell, Gillian L.; Munson, Amanda M.; Croston, Merriah A.; Rosenwald, Anne G.

    2011-01-01

    Using the homozygous diploid Saccharomyces deletion collection, we searched for strains with defects in K+ homeostasis. We identified 156 (of 4653 total) strains unable to grow in the presence of hygromycin B, a phenotype previously shown to be indicative of ion defects. The most abundant group was that with deletions of genes known to encode membrane traffic regulators. Nearly 80% of these membrane traffic defective strains showed defects in uptake of the K+ homolog, 86Rb+. Since Trk1, a plasma membrane protein localized to lipid microdomains, is the major K+ influx transporter, we examined the subcellular localization and Triton-X 100 insolubility of Trk1 in 29 of the traffic mutants. However, few of these showed defects in the steady state levels of Trk1, the localization of Trk1 to the plasma membrane, or the localization of Trk1 to lipid microdomains, and most defects were mild compared to wild-type. Three inositol kinase mutants were also identified, and in contrast, loss of these genes negatively affected Trk1 protein levels. In summary, this work reveals a nexus between K+ homeostasis and membrane traffic, which does not involve traffic of the major influx transporter, Trk1. PMID:22384317

  11. Identification of yeast genes involved in k homeostasis: loss of membrane traffic genes affects k uptake.

    PubMed

    Fell, Gillian L; Munson, Amanda M; Croston, Merriah A; Rosenwald, Anne G

    2011-06-01

    Using the homozygous diploid Saccharomyces deletion collection, we searched for strains with defects in K(+) homeostasis. We identified 156 (of 4653 total) strains unable to grow in the presence of hygromycin B, a phenotype previously shown to be indicative of ion defects. The most abundant group was that with deletions of genes known to encode membrane traffic regulators. Nearly 80% of these membrane traffic defective strains showed defects in uptake of the K(+) homolog, (86)Rb(+). Since Trk1, a plasma membrane protein localized to lipid microdomains, is the major K(+) influx transporter, we examined the subcellular localization and Triton-X 100 insolubility of Trk1 in 29 of the traffic mutants. However, few of these showed defects in the steady state levels of Trk1, the localization of Trk1 to the plasma membrane, or the localization of Trk1 to lipid microdomains, and most defects were mild compared to wild-type. Three inositol kinase mutants were also identified, and in contrast, loss of these genes negatively affected Trk1 protein levels. In summary, this work reveals a nexus between K(+) homeostasis and membrane traffic, which does not involve traffic of the major influx transporter, Trk1.

  12. Hybrid Adsorption-Membrane Biological Reactors for Improved Performance and Reliability of Perchlorate Removal Processes

    DTIC Science & Technology

    2008-12-01

    carbon supply for the autotrophic perchlorate reducing bacteria. The membrane used in the reactor is a hollow-fiber microfiltration membrane made from...1 HYBRID ADSORPTION- MEMBRANE BIOLOGICAL REACTORS FOR IMPROVED PERFORMANCE AND RELIABILITY OF PERCHLORATE REMOVAL PROCESSES L.C. Schideman...Center Champaign, IL 61826, USA ABSTRACT This study introduces the novel HAMBgR process (Hybrid Adsorption Membrane Biological Reactor) and

  13. Factors Affecting Performance of Undergraduate Students in Construction Related Disciplines

    ERIC Educational Resources Information Center

    Olatunji, Samuel Olusola; Aghimien, Douglas Omoregie; Oke, Ayodeji Emmanuel; Olushola, Emmanuel

    2016-01-01

    Academic performance of students in Nigerian institutions has been of much concern to all and sundry hence the need to assess the factors affecting performance of undergraduate students in construction related discipline in Nigeria. A survey design was employed with questionnaires administered on students in the department of Quantity Surveying,…

  14. Focus of Attention Affects Performance of Motor Skills in Music

    ERIC Educational Resources Information Center

    Duke, Robert A.; Cash, Carla Davis; Allen, Sarah E.

    2011-01-01

    To test the extent to which learners performing a simple keyboard passage would be affected by directing their focus of attention to different aspects of their movements, 16 music majors performed a brief keyboard passage under each of four focus conditions arranged in a counterbalanced design--a total of 64 experimental sessions. As they…

  15. Graphene-doped electrospun nanofiber membrane electrodes and proton exchange membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Wei, Meng; Jiang, Min; Liu, Xiaobo; Wang, Min; Mu, Shichun

    2016-09-01

    A rational electrode structure can allow proton exchange membrane (PEM) fuel cells own high performance with a low noble metal loading and an optimal transport pathway for reaction species. In this study, we develop a graphene doped polyacrylonitile (PAN)/polyvinylident fluoride (PVDF) (GPP) electrospun nanofiber electrode with improved electrical conductivity and high porosity, which could enhance the triple reaction boundary and promote gas and water transport throughout the porous electrode. Thus the increased electrochemical active surface area (ECSA) of Pt catalysts and fuel cell performance can be expected. As results, the ECSA of hot-pressed electrospun electrodes with 2 wt% graphene oxide (GO) is up to 84.3 m2/g, which is greatly larger than that of the conventional electrode (59.5 m2/g). Significantly, the GPP nanofiber electrospun electrode with Pt loading of 0.2 mg/cm2 exhibits higher fuel cell voltage output and stability than the conventional electrode.

  16. Microvillus inclusion disease: a genetic defect affecting apical membrane protein traffic in intestinal epithelium.

    PubMed

    Ameen, N A; Salas, P J

    2000-01-01

    The striking similarities between microvillus inclusions (MIs) in enterocytes in microvillus inclusion disease (MID) and vacuolar apical compartment in tissue culture epithelial cells, led us to analyze endoscopic biopsies of duodenal mucosa of a patient after the samples were used for diagnostic procedures. Samples from another patient with an unrelated disease were used as controls. The MID enterocytes showed a decrease in the thickness of the apical F-actin layer, and normal microtubules. The immunofluorescence analysis of the distribution of five apical membrane markers (sucrase isomaltase, alkaline phosphatase, NHE-3 Na+/H+ exchanger, cGMP-dependent protein kinase, and cystic fibrosis trans-membrane conductance regulator), showed low levels of these proteins in their standard localization at the apical membrane as compared with normal duodenal epithelium processed in parallel. Instead, four of these markers were found in a diffuse distribution in the apical cytoplasm, below the terminal web (as indicated by co-localization with F-actin and cytokeratin 19), and in MIs as well. The basolateral protein Na(+)-K+ATPase, in contrast, was normally localized. These results support the hypothesis that MID may represent the first genetic defect affecting apical membrane traffic, possibly in a late step of apical exocytosis.

  17. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Schluesener, Hermann J.

    2010-03-01

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  18. Predicting performance expectations from affective impressions: linking affect control theory and status characteristics theory.

    PubMed

    Dippong, Joseph; Kalkhoff, Will

    2015-03-01

    Affect control theory (ACT) and status characteristics theory (SCT) offer separate and distinct explanations for how individuals interpret and process status- and power-relevant information about interaction partners. Existing research within affect control theory offers evidence that status and power are related to the affective impressions that individuals form of others along the dimensions of evaluation and potency, respectively. Alternately, status characteristics theory suggests that status and power influence interaction through the mediating cognitive construct of performance expectations. Although both theories have amassed an impressive amount of empirical support, research has yet to articulate theoretical and empirical connections between affective impressions and performance expectations. The purpose of our study is to address this gap. Elaborating a link between ACT and SCT in terms of their central concepts can serve as a stepping stone to improving the explanatory capacity of both theories, while providing a potential bridge by which they can be employed jointly.

  19. Preparation, characterization, physical testing and performance of fluorocarbon membranes and separators

    NASA Technical Reports Server (NTRS)

    Lagow, R. J.; Dumitru, E. T.

    1982-01-01

    The direct fluorination method of converting carefully selected hydrocarbon substrates to fluorinated membranes was successfully applied to produce promising, novel membranes for electrochemical devices. A family of polymer blends was identified which permits wide latitude in the concentration of both crosslinks and carboxyl groups in hydrocarbon membranes. These membranes were successfully fluorinated and are potentially competitive with commercial membranes in performance, and potentially much cheaper in price.

  20. Performance pressure and caffeine both affect cognitive performance, but likely through independent mechanisms.

    PubMed

    Boere, Julia J; Fellinger, Lizz; Huizinga, Duncan J H; Wong, Sebastiaan F; Bijleveld, Erik

    2016-02-01

    A prevalent combination in daily life, performance pressure and caffeine intake have both been shown to impact people's cognitive performance. Here, we examined the possibility that pressure and caffeine affect cognitive performance via a shared pathway. In an experiment, participants performed a modular arithmetic task. Performance pressure and caffeine intake were orthogonally manipulated. Findings indicated that pressure and caffeine both negatively impacted performance. However, (a) pressure vs. caffeine affected performance on different trial types, and (b) there was no hint of an interactive effect. So, though the evidence is indirect, findings suggest that pressure and caffeine shape performance via distinct mechanisms, rather than a shared one.

  1. The Evolutionarily Conserved Protein PHOTOSYNTHESIS AFFECTED MUTANT71 Is Required for Efficient Manganese Uptake at the Thylakoid Membrane in Arabidopsis

    PubMed Central

    Steinberger, Iris; Herdean, Andrei; Gandini, Chiara; Labs, Mathias; Flügge, Ulf-Ingo; Geimer, Stefan; Schmidt, Sidsel Birkelund; Husted, Søren; Spetea, Cornelia; Leister, Dario

    2016-01-01

    In plants, algae, and cyanobacteria, photosystem II (PSII) catalyzes the light-driven oxidation of water. The oxygen-evolving complex of PSII is a Mn4CaO5 cluster embedded in a well-defined protein environment in the thylakoid membrane. However, transport of manganese and calcium into the thylakoid lumen remains poorly understood. Here, we show that Arabidopsis thaliana PHOTOSYNTHESIS AFFECTED MUTANT71 (PAM71) is an integral thylakoid membrane protein involved in Mn2+ and Ca2+ homeostasis in chloroplasts. This protein is required for normal operation of the oxygen-evolving complex (as evidenced by oxygen evolution rates) and for manganese incorporation. Manganese binding to PSII was severely reduced in pam71 thylakoids, particularly in PSII supercomplexes. In cation partitioning assays with intact chloroplasts, Mn2+ and Ca2+ ions were differently sequestered in pam71, with Ca2+ enriched in pam71 thylakoids relative to the wild type. The changes in Ca2+ homeostasis were accompanied by an increased contribution of the transmembrane electrical potential to the proton motive force across the thylakoid membrane. PSII activity in pam71 plants and the corresponding Chlamydomonas reinhardtii mutant cgld1 was restored by supplementation with Mn2+, but not Ca2+. Furthermore, PAM71 suppressed the Mn2+-sensitive phenotype of the yeast mutant Δpmr1. Therefore, PAM71 presumably functions in Mn2+ uptake into thylakoids to ensure optimal PSII performance. PMID:27020959

  2. The fat of the matter: how dietary fatty acids can affect exercise performance.

    PubMed

    Pierce, Barbara J; McWilliams, Scott R

    2014-11-01

    Fatty-acid composition of fat stores affects exercise performance in a variety of vertebrates although few such studies focus on flying vertebrates such as migratory birds, which are exceptional exercisers. We first discuss the natural variation in quality of fat available in natural foods eaten by migratory birds and their behavioral preferences for specific fatty acids in these foods. We then outline three proposed hypotheses for how dietary fatty acids can affect exercise performance, and some of the evidence to date that pertains to these hypotheses with special emphasis on the exercise performance of migratory birds. In theory, selectively feeding on certain long-chain unsaturated fatty acids may be advantageous because (1) such fatty acids may be metabolized more quickly and may stimulate key facets of aerobic metabolism (fuel hypothesis); (2) such fatty acids may affect composition and key functions of lipid-rich cell membranes (membrane hypothesis); and (3) such fatty acids may directly act as signaling molecules (signal hypothesis). Testing these hypotheses requires cleverly designed experiments that can distinguish between them by demonstrating that certain fatty acids stimulate oxidative capacity, including gene expression and activity of key oxidative enzymes, and that this stimulation changes during exercise.

  3. Principals' Perception regarding Factors Affecting the Performance of Teachers

    ERIC Educational Resources Information Center

    Akram, Muhammad Javaid; Raza, Syed Ahmad; Khaleeq, Abdur Rehman; Atika, Samrana

    2011-01-01

    This study investigated the perception of principals on how the factors of subject mastery, teaching methodology, personal characteristics, and attitude toward students affect the performance of teachers at higher secondary level in the Punjab. All principals of higher secondary level in the Punjab were part of the population of the study. From…

  4. Factors Affecting Performance in an Introductory Sociology Course

    ERIC Educational Resources Information Center

    Kwenda, Maxwell

    2011-01-01

    This study examines factors affecting students' performances in an Introductory Sociology course over five semesters. Employing simple and ordered logit regression models, the author explains final grades by focusing on individual demographic and educational characteristics that students bring into the classroom. The results show that a student's…

  5. Effect of ozone on the performance of a hybrid ceramic membrane-biological activated carbon process.

    PubMed

    Guo, Jianning; Hu, Jiangyong; Tao, Yi; Zhu, Jia; Zhang, Xihui

    2014-04-01

    Two hybrid processes including ozonation-ceramic membrane-biological activated carbon (BAC) (Process A) and ceramic membrane-BAC (Process B) were compared to treat polluted raw water. The performance of hybrid processes was evaluated with the removal efficiencies of turbidity, ammonia and organic matter. The results indicated that more than 99% of particle count was removed by both hybrid processes and ozonation had no significant effect on its removal. BAC filtration greatly improved the removal of ammonia. Increasing the dissolved oxygen to 30.0 mg/L could lead to a removal of ammonia with concentrations as high as 7.80 mg/L and 8.69 mg/L for Processes A and B, respectively. The average removal efficiencies of total organic carbon and ultraviolet absorbance at 254 nm (UV254, a parameter indicating organic matter with aromatic structure) were 49% and 52% for Process A, 51% and 48% for Process B, respectively. Some organic matter was oxidized by ozone and this resulted in reduced membrane fouling and increased membrane flux by 25%-30%. However, pre-ozonation altered the components of the raw water and affected the microorganisms in the BAC, which may impact the removals of organic matter and nitrite negatively.

  6. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production

    PubMed Central

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role. PMID:26217252

  7. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production.

    PubMed

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role.

  8. Preparatory power posing affects nonverbal presence and job interview performance.

    PubMed

    Cuddy, Amy J C; Wilmuth, Caroline A; Yap, Andy J; Carney, Dana R

    2015-07-01

    The authors tested whether engaging in expansive (vs. contractive) "power poses" before a stressful job interview--preparatory power posing--would enhance performance during the interview. Participants adopted high-power (i.e., expansive, open) poses or low-power (i.e., contractive, closed) poses, and then prepared and delivered a speech to 2 evaluators as part of a mock job interview. All interview speeches were videotaped and coded for overall performance and hireability and for 2 potential mediators: verbal content (e.g., structure, content) and nonverbal presence (e.g., captivating, enthusiastic). As predicted, those who prepared for the job interview with high- (vs. low-) power poses performed better and were more likely to be chosen for hire; this relation was mediated by nonverbal presence, but not by verbal content. Although previous research has focused on how a nonverbal behavior that is enacted during interactions and observed by perceivers affects how those perceivers evaluate and respond to the actor, this experiment focused on how a nonverbal behavior that is enacted before the interaction and unobserved by perceivers affects the actor's performance, which, in turn, affects how perceivers evaluate and respond to the actor. This experiment reveals a theoretically novel and practically informative result that demonstrates the causal relation between preparatory nonverbal behavior and subsequent performance and outcomes.

  9. How motivation affects academic performance: a structural equation modelling analysis.

    PubMed

    Kusurkar, R A; Ten Cate, Th J; Vos, C M P; Westers, P; Croiset, G

    2013-03-01

    Few studies in medical education have studied effect of quality of motivation on performance. Self-Determination Theory based on quality of motivation differentiates between Autonomous Motivation (AM) that originates within an individual and Controlled Motivation (CM) that originates from external sources. To determine whether Relative Autonomous Motivation (RAM, a measure of the balance between AM and CM) affects academic performance through good study strategy and higher study effort and compare this model between subgroups: males and females; students selected via two different systems namely qualitative and weighted lottery selection. Data on motivation, study strategy and effort was collected from 383 medical students of VU University Medical Center Amsterdam and their academic performance results were obtained from the student administration. Structural Equation Modelling analysis technique was used to test a hypothesized model in which high RAM would positively affect Good Study Strategy (GSS) and study effort, which in turn would positively affect academic performance in the form of grade point averages. This model fit well with the data, Chi square = 1.095, df = 3, p = 0.778, RMSEA model fit = 0.000. This model also fitted well for all tested subgroups of students. Differences were found in the strength of relationships between the variables for the different subgroups as expected. In conclusion, RAM positively correlated with academic performance through deep strategy towards study and higher study effort. This model seems valid in medical education in subgroups such as males, females, students selected by qualitative and weighted lottery selection.

  10. Sleep complaints affecting school performance at different educational levels.

    PubMed

    Pagel, James F; Kwiatkowski, Carol F

    2010-01-01

    The clear association between reports of sleep disturbance and poor school performance has been documented for sleepy adolescents. This study extends that research to students outside the adolescent age grouping in an associated school setting (98 middle school students, 67 high school students, and 64 college students). Reported restless legs and periodic limb movements are significantly associated with lower GPA's in junior high students. Consistent with previous studies, daytime sleepiness was the sleep variable most likely to negatively affects high school students. Sleep onset and maintenance insomnia were the reported sleep variables significantly correlated with poorer school performance in college students. This study indicates that different sleep disorder variables negatively affect performance at different age and educational levels.

  11. PMCA activity and membrane tubulin affect deformability of erythrocytes from normal and hypertensive human subjects.

    PubMed

    Monesterolo, Noelia E; Nigra, Ayelen D; Campetelli, Alexis N; Santander, Verónica S; Rivelli, Juan F; Arce, Carlos A; Casale, Cesar H

    2015-11-01

    Our previous studies demonstrated formation of a complex between acetylated tubulin and brain plasma membrane Ca(2+)-ATPase (PMCA), and the effect of the lipid environment on structure of this complex and on PMCA activity. Deformability of erythrocytes from hypertensive human subjects was reduced by an increase in membrane tubulin content. In the present study, we examined the regulation of PMCA activity by tubulin in normotensive and hypertensive erythrocytes, and the effect of exogenously added diacylglycerol (DAG) and phosphatidic acid (PA) on erythrocyte deformability. Some of the key findings were that: (i) PMCA was associated with tubulin in normotensive and hypertensive erythrocytes, (ii) PMCA enzyme activity was directly correlated with erythrocyte deformability, and (iii) when tubulin was present in the erythrocyte membrane, treatment with DAG or PA led to increased deformability and associated PMCA activity. Taken together, our findings indicate that PMCA activity is involved in deformability of both normotensive and hypertensive erythrocytes. This rheological property of erythrocytes is affected by acetylated tubulin and its lipid environment because both regulate PMCA activity.

  12. Effect of titania nanotubes on the flux and separation performance of polyethersulfone membranes

    NASA Astrophysics Data System (ADS)

    Subramaniam, M. N.; Goh, P. S.; Ismail, A. F.; Lau, W. J.

    2016-06-01

    The improvement of membrane performances in terms of separation and permeation is a constant research problem. In this study, polyethersulfone (PES) hollow fiber nanocomposite membranes were fabricated with titania nanotubes (TNT) synthesized via hydrothermal method used as inorganic filler to improve separation and membrane permeation. The membranes were prepared using dry/wet phase inversion process. The concentration of PES was fixed at 18% and TNT was added at concentration of 0.1% wt. The membranes were characterized in terms of pure water permeation rate (PWP), proteins (BSA) rejection, porosity and water contact angle. The results showed that addition of TNT improves the water flux and rejection rate as well as increasing hydrophilicity of the membrane. The flux of membrane is improved more than 20% while the rejection has been improved from 79% to 96%. The addition of TNT into the membrane matrix has shown that photocatalytic property can be introduced to a normal membrane.

  13. Tailoring the structure of thin film nanocomposite membranes to achieve seawater RO membrane performance.

    PubMed

    Lind, Mary Laura; Eumine Suk, Daniel; Nguyen, The-Vinh; Hoek, Eric M V

    2010-11-01

    Herein we report on the formation and characterization of pure polyamide thin film composite (TFC) and zeolite-polyamide thin film nanocomposite (TFN) reverse osmosis (RO) membranes. Four different physical-chemical post-treatment combinations were applied after the interfacial polymerization reaction to change the molecular structure of polyamide and zeolite-polyamide thin films. Both TFC and TFN hand-cast membranes were more permeable, hydrophilic, and rough than a commercial seawater RO membrane. Salt rejection by TFN membranes was consistently below that of hand-cast TFC membranes; however, two TFN membranes exhibited 32 g/L NaCl rejections above 99.4%, which was better than the commercial membrane under the test conditions employed. The nearly defect-free TFN films that produced such high rejections were achieved only with wet curing, regardless of other post-treatments. Polyamide films formed in the presence of zeolite nanoparticles were less cross-linked than similarly cast pure polyamide films. At the very low nanoparticle loadings evaluated, differences between pure polyamide and zeolite-polyamide membrane water and salt permeability correlated weakly with extent of cross-linking of the polyamide film, which suggests that defects and molecular-sieving largely govern transport through zeolite-polyamide thin film nanocomposite membranes.

  14. Factors Affecting Polymer Electrolyte Fuel Cells Performance and Reproducibility

    SciTech Connect

    Moller-Holst S.

    1998-11-01

    Development of fuel cells is often based on small-scale laboratory studies. Due to limited time and budgets, a minimum number of cells are usually prepared and tested, thus, conclusions about improved performance are often drawn from studies of a few cells. Generally, statistics showing the significance of an effect are seldom reported. In this work a simple PEM fuel cell electrode optimization experiment is used as an example to illustrate the importance of statistical evaluation of factors affecting cell performance. The use of fractional factorial design of experiments to reduce the number of cells that have to be studied is also addressed.

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

    NASA Astrophysics Data System (ADS)

    Mulijani, S.

    2016-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Mulijani, S.

    2017-01-01

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

  17. The double effects of silver nanoparticles on the PVDF membrane: Surface hydrophilicity and antifouling performance

    NASA Astrophysics Data System (ADS)

    Li, Jian-Hua; Shao, Xi-Sheng; Zhou, Qing; Li, Mi-Zi; Zhang, Qi-Qing

    2013-01-01

    In this study, silver nanoparticles were used to endow poly(vinylidene fluoride) (PVDF) membrane with excellent surface hydrophilicity and outstanding antifouling performance. Silver nanoparticles were successfully immobilized onto PVDF membrane surface under the presence of poly(acrylic acid) (PAA). The double effects of silver nanoparticles on PVDF membrane, i.e., surface hydrophilicity and anti-fouling performance, were systematically investigated. Judging from result of water static contact measurement, silver nanoparticles had provided a significant improvement in PVDF membrane surface hydrophilicity. And the possible explanation on the improvement of PVDF membrane surface hydrophilicity with silver nanoparticles was firstly proposed in this study. Membrane permeation and anti-bacterial tests were carried out to characterize the antifouling performance of PVDF membrane. Flux recovery ratio (FRR) increased about 40% after the presence of silver nanoparticles on the PVDF membrane surface, elucidating the anti-organic fouling performance of PVDF membrane was elevated by silver nanoparticles. Simultaneously, anti-bacterial test confirmed that PVDF membrane showed superior anti-biofouling activity because of silver nanoparticles. The above-mentioned results clarified that silver nanoparticles can endow PVDF membrane with both excellent surface hydrophilicity and outstanding antifouling performance in this study.

  18. Enhanced performance of PVDF nanocomposite membrane by nanofiber coating: A membrane for sustainable desalination through MD.

    PubMed

    Efome, Johnson E; Rana, Dipak; Matsuura, Takeshi; Lan, Christopher Q

    2016-02-01

    Membrane distillation (MD) is a promising separation technique capable of being used in the desalination of marine and brackish water. Poly(vinylidene fluoride) (PVDF) flat sheet nano-composite membranes were surface modified by coating with electro-spun PVDF nano-fibres to increase the surface hydrophobicity. For this purpose, the nano-composite membrane containing 7 wt.% superhydrophobic SiO2 nano-particles, which showed the highest flux in our previous work, was first subjected to pore size augmentation by increasing the concentration of the pore forming agent (Di-ionized water). Then, the prepared flat sheet membranes were subjected to nanofibres coating by electro-spinning. The uncoated and coated composite fabricated membranes were characterized using contact angle, liquid entry pressure of water, and scanning electron microscopy. The membranes were further tested for 6 h desalination by direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD), with a 3.5 wt.% synthetic NaClaq as the feed. In DCMD the feed liquid and permeate side temperature were maintained at 27.5 °C and 15 °C, respectively. For VMD, the feed liquid temperature was 27 °C and a vacuum of 94.8 kPa was applied on the permeate side. The maximum permeate flux achieved was 3.2 kg/m(2).h for VMD and 6.5 kg/m(2).h for DCMD. The salt rejection obtained was higher than 99.98%. The coated membranes showed a more stable flux than the uncoated membranes indicating that the double layered membranes have great potential in solving the pore wetting problem in MD.

  19. Renewable energy powered membrane technology. 2. The effect of energy fluctuations on performance of a photovoltaic hybrid membrane system.

    PubMed

    Richards, B S; Capão, D P S; Schäfer, A I

    2008-06-15

    This paper reports on the performance fluctuations during the operation of a batteryless hybrid ultrafiltration--nanofiltration/reverse osmosis (UF-NF/RO) membrane desalination system powered by photovoltaics treating brackish groundwater in outback Australia. The renewable energy powered membrane (RE-membrane) system is designed to supply clean drinking water to a remote community of about 50 inhabitants. The performance of the RE-membrane system over four different solar days is summarized using four different NF membranes (BW30, NF90, ESPA4, TFC-S), and examined in more detail for the BW30 membrane. On an Australian spring day, the system produced 1.1 m3 of permeate with an average conductivity of 0.28 mS x cm(-1), recovering 28% of the brackish (8.29 mS x cm(-1) conductivity) feedwater with an average specific energy consumption of 2.3 kWh x m(-3). The RE-membrane system tolerated large fluctuations in solar irradiance (500--1200 W x m(-2)), resulting in only small increases in the permeate conductivity. When equipped with the NF90 (cloudy day) and ESPA4 (rainy day) membranes, the system was still able to produce 1.36 m(-3) and 0.85 m(-3) of good quality permeate, respectively. The TFC-S membrane was not able to produce adequate water quality from the bore water tested. It is concluded that batteryless operation is a simple and robust way to operate such systems under conditions ranging from clear skies to medium cloud cover.

  20. Binaural auditory beats affect vigilance performance and mood.

    PubMed

    Lane, J D; Kasian, S J; Owens, J E; Marsh, G R

    1998-01-01

    When two tones of slightly different frequency are presented separately to the left and right ears the listener perceives a single tone that varies in amplitude at a frequency equal to the frequency difference between the two tones, a perceptual phenomenon known as the binaural auditory beat. Anecdotal reports suggest that binaural auditory beats within the electroencephalograph frequency range can entrain EEG activity and may affect states of consciousness, although few scientific studies have been published. This study compared the effects of binaural auditory beats in the EEG beta and EEG theta/delta frequency ranges on mood and on performance of a vigilance task to investigate their effects on subjective and objective measures of arousal. Participants (n = 29) performed a 30-min visual vigilance task on three different days while listening to pink noise containing simple tones or binaural beats either in the beta range (16 and 24 Hz) or the theta/delta range (1.5 and 4 Hz). However, participants were kept blind to the presence of binaural beats to control expectation effects. Presentation of beta-frequency binaural beats yielded more correct target detections and fewer false alarms than presentation of theta/delta frequency binaural beats. In addition, the beta-frequency beats were associated with less negative mood. Results suggest that the presentation of binaural auditory beats can affect psychomotor performance and mood. This technology may have applications for the control of attention and arousal and the enhancement of human performance.

  1. Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

    2015-11-01

    Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations.

  2. Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

    PubMed Central

    Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

    2015-01-01

    Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations. PMID:26552839

  3. Partial calcium depletion during membrane filtration affects gelation of reconstituted milk protein concentrates.

    PubMed

    Eshpari, H; Jimenez-Flores, R; Tong, P S; Corredig, M

    2015-12-01

    Milk protein concentrate powders (MPC) with improved rehydration properties are often manufactured using processing steps, such as acidification and high-pressure processing, and with addition of other ingredients, such as sodium chloride, during their production. These steps are known to increase the amount of serum caseins or modify the mineral equilibrium, hence improving solubility of the retentates. The processing functionality of the micelles may be affected. The aim of this study was to investigate the effects of partial acidification by adding glucono-δ-lactone (GDL) to skim milk during membrane filtration on the structural changes of the casein micelles by observing their chymosin-induced coagulation behavior, as such coagulation is affected by both the supramolecular structure of the caseins and calcium equilibrium. Milk protein concentrates were prepared by preacidification with GDL to pH 6 using ultrafiltration (UF) and diafiltration (DF) followed by spray-drying. Reconstituted UF and DF samples (3.2% protein) treated with GDL showed significantly increased amounts of soluble calcium and nonsedimentable caseins compared with their respective controls, as measured by ion chromatography and sodium dodecyl sulfate-PAGE electrophoresis, respectively. The primary phase of chymosin-induced gelation was not significantly different between treatments as measured by the amount of caseino-macropeptide released. The rheological properties of the reconstituted MPC powders were determined immediately after addition of chymosin, both before and after dialysis against skim milk, to ensure similar serum composition for all samples. Reconstituted samples before dialysis showed no gelation (defined as tan δ=1), and after re-equilibration only control UF and DF samples showed gelation. The gelation properties of reconstituted MPC powders were negatively affected by the presence of soluble casein, and positively affected by the amount of both soluble and insoluble

  4. Membrane transporters and protein traffic networks differentially affecting metal tolerance: a genomic phenotyping study in yeast

    PubMed Central

    Ruotolo, Roberta; Marchini, Gessica; Ottonello, Simone

    2008-01-01

    Background The cellular mechanisms that underlie metal toxicity and detoxification are rather variegated and incompletely understood. Genomic phenotyping was used to assess the roles played by all nonessential Saccharomyces cerevisiae proteins in modulating cell viability after exposure to cadmium, nickel, and other metals. Results A number of novel genes and pathways that affect multimetal as well as metal-specific tolerance were discovered. Although the vacuole emerged as a major hot spot for metal detoxification, we also identified a number of pathways that play a more general, less direct role in promoting cell survival under stress conditions (for example, mRNA decay, nucleocytoplasmic transport, and iron acquisition) as well as proteins that are more proximally related to metal damage prevention or repair. Most prominent among the latter are various nutrient transporters previously not associated with metal toxicity. A strikingly differential effect was observed for a large set of deletions, the majority of which centered on the ESCRT (endosomal sorting complexes required for transport) and retromer complexes, which - by affecting transporter downregulation and intracellular protein traffic - cause cadmium sensitivity but nickel resistance. Conclusion The data show that a previously underestimated variety of pathways are involved in cadmium and nickel tolerance in eukaryotic cells. As revealed by comparison with five additional metals, there is a good correlation between the chemical properties and the cellular toxicity signatures of various metals. However, many conserved pathways centered on membrane transporters and protein traffic affect cell viability with a surprisingly high degree of metal specificity. PMID:18394190

  5. Membrane protein assembly: two cytoplasmic phosphorylated serine sites of Vpu from HIV-1 affect oligomerization

    PubMed Central

    Chen, Chin-Pei; Lin, Meng-Han; Chan, Ya-Ting; Chen, Li-Chyong; Ma, Che; Fischer, Wolfgang B.

    2016-01-01

    Viral protein U (Vpu) encoded by human immunodeficiency virus type 1 (HIV-1) is a short integral membrane protein which is known to self-assemble within the lipid membrane and associate with host factors during the HIV-1 infectivity cycle. In this study, full-length Vpu (M group) from clone NL4-3 was over-expressed in human cells and purified in an oligomeric state. Various single and double mutations were constructed on its phosphorylation sites to mimic different degrees of phosphorylation. Size exclusion chromatography of wild-type Vpu and mutants indicated that the smallest assembly unit of Vpu was a dimer and over time Vpu formed higher oligomers. The rate of oligomerization increased when (i) the degree of phosphorylation at serines 52 and 56 was decreased and (ii) when the ionic strength was increased indicating that the cytoplasmic domain of Vpu affects oligomerization. Coarse-grained molecular dynamic simulations with models of wild-type and mutant Vpu in a hydrated lipid bilayer supported the experimental data in demonstrating that, in addition to a previously known role in downregulation of host factors, the phosphorylation sites of Vpu also modulate oligomerization. PMID:27353136

  6. Does Question Structure Affect Exam Performance in the Geosciences?

    NASA Astrophysics Data System (ADS)

    Day, E. A.; D'Arcy, M. K.; Craig, L.; Streule, M. J.; Passmore, E.; Irving, J. C. E.

    2015-12-01

    The jump to university level exams can be challenging for some students, often resulting in poor marks, which may be detrimental to their confidence and ultimately affect their overall degree class. Previous studies have found that question structure can have a strong impact on the performance of students in college level exams (see Gibson et al., 2015, for a discussion of its impact on physics undergraduates). Here, we investigate the effect of question structure on the exam results of geology and geophysics undergraduate students. Specifically, we analyse the performance of students in questions that have a 'scaffolded' framework and compare them to their performance in open-ended questions and coursework. We also investigate if observed differences in exam performance are correlated with the educational background and gender of students, amongst other factors. It is important for all students to be able to access their degree courses, no matter what their backgrounds may be. Broadening participation in the geosciences relies on removing systematic barriers to achievement. Therefore we recommend that exams are either structured with scaffolding in questions at lower levels, or students are explicitly prepared for this transition. We also recommend that longitudinal studies of exam performance are conducted within individual departments, and this work outlines one approach to analysing performance data.

  7. Breakthrough performance of linear-DNA on ion-exchange membrane columns.

    PubMed

    Ma Montesinos-Cisneros, Rosa; Ortega, Jaime; Guzmán, Roberto; Tejeda-Mansir, Armando

    2006-07-01

    Breakthrough performance of linear-DNA adsorption on ion-exchange membrane columns was theoretically and experimentally investigated using batch and fixed-bed systems. System dispersion curves showed the absence of flow non-idealities in the experimental arrangement. Breakthrough curves were not significantly affected by flow-rate or inlet solution concentration. In the theoretical analysis a model was integrated by the serial coupling of the membrane transport model and the system dispersion model. A transport model that considers finite kinetic rate and column dispersed flow was used in the study. A simplex optimization routine coupled to the solution of the partial differential model equations was employed to estimate the maximum adsorption capacity constant, the equilibrium desorption constant and the forward interaction rate-constant, which are the parameters of the membrane transport model. Through this approach a good prediction of the adsorption phenomena is obtained for inlet concentrations and flow rates greater than 0.2 mg/ml and 0.16 ml/min.

  8. Effect of low dosage of coagulant on the ultrafiltration membrane performance in feedwater treatment.

    PubMed

    Ma, Baiwen; Yu, Wenzheng; Liu, Huijuan; Qu, Jiuhui

    2014-03-15

    One of the critical issues for the widely application of ultrafiltration (UF) in water treatment is membrane fouling owning to the dissolved organic matter. The aim of the present study is to explore the effect of various particle sizes caused by low dosages of coagulant with dissolved organic matter on the UF membrane performance. Aluminum chloride was added to the synthetic water with the hydrophobic humic acid (HA), the hydrophilic bovine serum albumin (BSA) - a protein- and their 1:1 (mass ratio) mixture. The results showed that there was a critical dose of Al that could cause dramatic flux reduction by blocking the membrane pores after coagulating with HA/BSA. For HA or BSA, the critical dose of Al was relatively lower at pH 6.0 than that at pH 8.0. After coagulation, the flux decline caused by HA was slightly varied as a function of pH while that caused by BSA was greatly affected by pH. The flux decline caused by the 1:1 (mass ratio) HA/BSA mixture after coagulation was similar to that caused by HA after coagulation because BSA could be encapsulated by HA. In addition, the peak value of the molecular weight (MW) distribution of HA coagulated with Al was changed more drastically compared to that of BSA after filtration.

  9. Breakthrough performance of plasmid DNA on ion-exchange membrane columns.

    PubMed

    Montesinos-Cisneros, Rosa Ma; Olivas, Jonathan de la Vega; Ortega, Jaime; Guzmán, Roberto; Tejeda-Mansir, Armando

    2007-01-01

    Breakthrough performance of plasmid DNA adsorption on ion-exchange membrane columns was theoretically and experimentally investigated using batch and fixed-bed systems. System dispersion curves showed the absence of flow non-idealities in the experimental arrangement. Breakthrough curves (BTC) were significantly affected by inlet flow rate and solute concentration. In the theoretical analysis, a model was integrated by the serial coupling of the membrane transport model and the system dispersion model. A transport model that considers finite kinetic rate and column dispersed flow was used in the study. A simplex optimization routine, coupled to the solution of the partial differential model equations, was employed to estimate the maximum adsorption capacity constant, the equilibrium desorption constant, and the forward interaction rate constant, which are the parameters of the membrane transport model. The analysis shows that as inlet concentration or flow rate increases, the deviation of the model from the experimental behavior decreases. The BTCs displacement as inlet concentration increases was explained in terms of a greater degree of column saturation reached and more efficient operation accomplished. The degree of column saturation was not influenced by inlet flow rate. It was necessary to consider in the column model the slight variation in the BTC produced by the axial dispersion, in order to accomplish the experimental curve dispersion. Consequently, the design criteria that for Pe > 40 the column axial dispersion can be neglected should be taken with precaution.

  10. Error framing effects on performance: cognitive, motivational, and affective pathways.

    PubMed

    Steele-Johnson, Debra; Kalinoski, Zachary T

    2014-01-01

    Our purpose was to examine whether positive error framing, that is, making errors salient and cuing individuals to see errors as useful, can benefit learning when task exploration is constrained. Recent research has demonstrated the benefits of a newer approach to training, that is, error management training, that includes the opportunity to actively explore the task and framing errors as beneficial to learning complex tasks (Keith & Frese, 2008). Other research has highlighted the important role of errors in on-the-job learning in complex domains (Hutchins, 1995). Participants (N = 168) from a large undergraduate university performed a class scheduling task. Results provided support for a hypothesized path model in which error framing influenced cognitive, motivational, and affective factors which in turn differentially affected performance quantity and quality. Within this model, error framing had significant direct effects on metacognition and self-efficacy. Our results suggest that positive error framing can have beneficial effects even when tasks cannot be structured to support extensive exploration. Whereas future research can expand our understanding of error framing effects on outcomes, results from the current study suggest that positive error framing can facilitate learning from errors in real-time performance of tasks.

  11. Dramatic improvement of membrane performance for microalgae harvesting with a simple bubble-generator plate.

    PubMed

    Hwang, Taewoon; Oh, You-Kwan; Kim, Bohwa; Han, Jong-In

    2015-06-01

    To overcome fouling issue in membrane-based algae harvesting and thus make an otherwise promising harvesting option more competitive, a bubble-generator plate was developed. According to computational fluid dynamics analysis, the plate generated substantial hydrodynamic power in terms of high pressure, velocity, and shear stress. When installed in a membrane filtration system with membranes of different surface and structural characteristics (one prepared by the phase inversion method, and a commercial one) the bubble-generator was indeed effective in reducing fouling. Without the plate, the much cheaper homemade membrane had the similar performance as the commercial one. Use of the bubble-generator considerably improved the performance of both membranes, and revealed a valuable synergy with the asymmetrical structure of the homemade membrane. This result clearly showed that the ever-problematic fouling could be mitigated in a rather easy manner, and in so doing, that membrane technology could indeed become a practical option for algae harvesting.

  12. Ensure the best performance from membranes and demineralizers

    SciTech Connect

    Strauss, S.D.

    1993-03-01

    This article discusses how the use of various membrane technologies to provide high-purity water for power generation has increased dramatically in the last 10 years. This trend has been driven primarily by three factors: (1) reduction in costs achieved through reduced chemical, operation, and maintenance requirements; (2) reduction of waste-treatment requirements in response to new environmental legislation; and (3) reduction of man-power requirements for monitoring regeneration of ion-exchange (IX) regenerations. The economic impact of membrane technology applied ahead of a makeup water demineralizer can be illustrated by a series of examples with three different waters, each used at three different flow rates. A cost analysis is provided for each case, before and after backfitting a membrane system. For perspective, the leading membrane technologies are reviewed first.

  13. Enhanced Performance of Polyurethane Hybrid Membranes for CO2 Separation by Incorporating Graphene Oxide: The Relationship between Membrane Performance and Morphology of Graphene Oxide.

    PubMed

    Wang, Ting; Zhao, Li; Shen, Jiang-nan; Wu, Li-guang; Van der Bruggen, Bart

    2015-07-07

    Polyurethane hybrid membranes containing graphene oxide (GO) with different morphologies were prepared by in situ polymerization. The separation of CO2/N2 gas mixtures was studied using these novel membranes. The results from the morphology characterization of GO samples indicated that the oxidation process in the improved Hummers method introduced oxygenated functional groups into graphite, making graphite powder exfoliate into GO nanosheets. The surface defects on the GO sheets increased when oxidation increased due to the introduction of more oxygenated functional groups. Both the increase in oxygenated functional groups on the GO surface and the decrease in the number of GO layers leads to a better distribution of GO in the polymer matrix, increasing thermal stability and gas separation performance of membranes. The addition of excess oxidant destroyed the structure of GO sheets and forms structural defects, which depressed the separation performance of membranes. The hybrid membranes containing well-distributed GO showed higher permeability and permeability selectivity for the CO2. The formation of GO aggregates in the hybrid membranes depressed the membrane performance at a high content of GO.

  14. Method for preparing membranes with adjustable separation performance

    DOEpatents

    Peterson, E.S.; Orme, C.J.; Stone, M.L.

    1995-01-31

    Methods for adjustable separation of solutes and solvents involve the combination of the use of a maximally swollen membrane and subsequent vacuum depressurization exerted on the permeate side of that membrane. By adjusting the extent of depressurization it is possible to separate solvent from solutes and solutes from each other. Improved control of separation parameters as well as improved flux rates characterize the present invention. 2 figs.

  15. Method for preparing membranes with adjustable separation performance

    DOEpatents

    Peterson, Eric S.; Orme, Christopher J.; Stone, Mark L.

    1995-01-01

    Methods for adjustable separation of solutes and solvents involve the combination of the use of a maximally swollen membrane and subsequent vacuum depressurization exerted on the permeate side of that membrane. By adjusting the extent of depressurization it is possible to separate solvent from solutes and solutes from each other. Improved control of separation parameters as well as improved flux rates characterize the present invention.

  16. Towards Enhanced Gas Sensor Performance with Fluoropolymer Membranes

    PubMed Central

    Graunke, Thorsten; Schmitt, Katrin; Raible, Stefan; Wöllenstein, Jürgen

    2016-01-01

    In this paper we report on how to increase the selectivity of gas sensors by using fluoropolymer membranes. The mass transport of polar and non-polar gases through a polymer membrane matrix was studied by systematic selection of polymers with different degrees of fluorination, as well as polymers whose monomers have ether groups (-O-) in addition to fluorine groups (-F). For the study, a set of application-relevant gases including H2, CO, CO2, NO2, methane, ethanol, acetone, and acetaldehyde as well as various concentrations of relative humidity were used. These gases have different functional groups and polarities, yet have a similar kinetic diameter and are therefore typically difficult to separate. The concentrations of the gases were chosen according to international indicative limit values (TWA, STEL). To measure the concentration in the feed and permeate, we used tin-dioxide-based metal oxide gas sensors with palladium catalyst (SnO2:Pd), catalytic sensors (also SnO2:Pd-based) and thermal conductivity sensors. This allows a close examination of the interdependence of diffusion and physicochemical operating principle of the sensor. Our goal is to increase the selectivity of gas sensors by using inexpensive fluoropolymer membranes. The measurements showed that through membranes with low polarity, preferably non-polar gases are transported. Furthermore, the degree of crystallization influences the permeability and selectivity of a polymer membrane. Basically the polar polymers showed a higher permeability to water vapor and polar substances than non-polar polymer membranes. PMID:27690045

  17. Effects of microbial degradation of biofoulants on microfiltration membrane performance in a membrane bioreactor.

    PubMed

    Okamura, Daisuke; Mori, Yoshihiko; Hashimoto, Tomotaka; Hori, Katsutoshi

    2010-11-15

    In membrane bioreactors (MBRs) for wastewater treatment, membrane fouling, particularly biofouling caused by soluble microbial products (SMP), is a nuisance problem causing decreases in permeation flux. In a previous study, we identified primary biofoulants of microfiltration (MF) membranes in SMP as polysaccharides containing uronic acids that undergo inter- and intramolecular ionic cross-linking by polyvalent cations, forming a gelatinous mass that clogs membrane pores. In the present study, we therefore attempted to isolate biofoulant-degrading microorganisms from activated sludge on a polygalacturonic acid-overlaid agar medium and evaluate their efficiency for preventing biofouling of MF membranes. Among the isolates, the fungal strain HO1 identified as Phialemonium curvatum degraded 30% of polysaccharides containing uronic acids into smaller molecules in a SMP solution containing a high concentration of saccharides after 30 days of cultivation. Microfiltration tests using a laboratory-scale submerged MBR indicated that the filtration resistance of this degraded SMP solution was lower than that of the control SMP solution without fungal inoculation. Importantly, accumulation of gelatinous mass on the membrane responsible for biofouling was avoided in the SMP solution augmented with P. curvatum HO1 during the microfiltration test. This is the first report to describe a new method for avoiding biofouling of MBRs by microbial degradation of primary biofoulants.

  18. Tail regeneration affects the digestive performance of a Mediterranean lizard

    NASA Astrophysics Data System (ADS)

    Sagonas, Kostas; Karambotsi, Niki; Bletsa, Aristoula; Reppa, Aikaterini; Pafilis, Panayiotis; Valakos, Efstratios D.

    2017-04-01

    In caudal autotomy, lizards shed their tail to escape from an attacking predator. Since the tail serves multiple functions, caudal regeneration is of pivotal importance. However, it is a demanding procedure that requires substantial energy and nutrients. Therefore, lizards have to increase energy income to fuel the extraordinary requirements of the regenerating tail. We presumed that autotomized lizards would adjust their digestion to acquire this additional energy. To clarify the effects of tail regeneration on digestion, we compared the digestive performance before autotomy, during regeneration, and after its completion. Tail regeneration indeed increased gut passage time but did not affect digestive performance in a uniform pattern: though protein income was maximized, lipid and sugar acquisition remained stable. This divergence in proteins may be attributed to their particular role in tail reconstruction, as they are the main building blocks for tissue formation.

  19. Can small shifts in circadian phase affect performance?

    PubMed Central

    Burgess, Helen J.; Legasto, Carlo S.; Fogg, Louis F.; Smith, Mark R.

    2012-01-01

    Small shifts in circadian timing occur frequently as a result of daylight saving time or later weekend sleep. These subtle shifts in circadian phase have been shown to influence subjective sleepiness, but it remains unclear if they can significantly affect performance. In a retrospective analysis we examined performance on the Psychomotor Vigilance Test before bedtime and after wake time in 11 healthy adults on fixed sleep schedules based on their habitual sleep times. The dim light melatonin onset, a marker of circadian timing, was measured on two occasions. An average 1.1 hour shift away from a proposed optimal circadian phase angle (6 hours between melatonin onset and midpoint of sleep) significantly slowed mean, median and fastest 10% reaction times before bedtime and after wake time (p<0.05). These results add to previous reports that suggest that humans may be sensitive to commonly occurring small shifts in circadian timing. PMID:22695081

  20. Can small shifts in circadian phase affect performance?

    PubMed

    Burgess, Helen J; Legasto, Carlo S; Fogg, Louis F; Smith, Mark R

    2013-01-01

    Small shifts in circadian timing occur frequently as a result of daylight saving time or later weekend sleep. These subtle shifts in circadian phase have been shown to influence subjective sleepiness, but it remains unclear if they can significantly affect performance. In a retrospective analysis we examined performance on the Psychomotor Vigilance Test before bedtime and after wake time in 11 healthy adults on fixed sleep schedules based on their habitual sleep times. The dim light melatonin onset, a marker of circadian timing, was measured on two occasions. An average 1.1 h shift away from a proposed optimal circadian phase angle (6 h between melatonin onset and midpoint of sleep) significantly slowed mean, median and fastest 10% reaction times before bedtime and after wake time (p < 0.05). These results add to previous reports that suggest that humans may be sensitive to commonly occurring small shifts in circadian timing.

  1. Performance of polydimethylsiloxane membrane contactor process for selective hydrogen sulfide removal from biogas.

    PubMed

    Tilahun, Ebrahim; Bayrakdar, Alper; Sahinkaya, Erkan; Çalli, Bariş

    2017-01-13

    H2S in biogas affects the co-generation performance adversely by corroding some critical components within the engine and it has to be removed in order to improve the biogas quality. This work presents the use of polydimethylsiloxane (PDMS) membrane contactor for selective removal of H2S from the biogas. Experiments were carried out to evaluate the effects of different pH of absorption liquid, biogas flowrate and temperature on the absorption performances. The results revealed that at the lowest loading rate (91mg H2S/m(2)·h) more than 98% H2S and 59% CO2 absorption efficiencies were achieved. The CH4 content in the treated gas increased from 60 to 80% with nearly 5% CH4 loss. Increasing the pH (7-10) and loading rate (91-355mg H2S/m(2)·h) enhanced the H2S absorption capacity, and the maximum H2S/CO2 and H2S/CH4 selectivity factors were 2.5 and 58, respectively. Temperature played a key role in the process and lower temperature was beneficial for intensifying H2S absorption performance. The highest H2S fluxes at pH 10 and 7 were 3.4g/m(2)·d and 1.8g/m(2)·d with overall mass transfer coefficients of 6.91×10(-6) and 4.99×10(-6)m/s, respectively. The results showed that moderately high H2S fluxes with low CH4 loss may be achieved by using a robust and cost-effective membrane based absorption process for desulfurization of biogas. A tubular PDMS membrane contactor was tested for the first time to remove H2S from biogas under slightly alkaline conditions and the suggested process could be a promising for real scale applications.

  2. Soluble Amyloid β-Oligomers Affect Dielectric Membrane Properties by Bilayer Insertion and Domain Formation: Implications for Cell Toxicity

    PubMed Central

    Valincius, Gintaras; Heinrich, Frank; Budvytyte, Rima; Vanderah, David J.; McGillivray, Duncan J.; Sokolov, Yuri; Hall, James E.; Lösche, Mathias

    2008-01-01

    It is well established that Alzheimer's amyloid β-peptides reduce the membrane barrier to ion transport. The prevailing model ascribes the resulting interference with ion homeostasis to the formation of peptide pores across the bilayer. In this work, we examine the interaction of soluble prefibrillar amyloid β (Aβ1–42)-oligomers with bilayer models, observing also dramatic increases in ion current at micromolar peptide concentrations. We demonstrate that the Aβ-induced ion conductances across free-standing membranes and across substrate-supported “tethered” bilayers are quantitatively similar and depend on membrane composition. However, characteristic signatures of the molecular transport mechanism were distinctly different from ion transfer through water-filled pores, as shown by a quantitative comparison of the membrane response to Aβ-oligomers and to the bacterial toxin α-hemolysin. Neutron reflection from tethered membranes showed that Aβ-oligomers insert into the bilayer, affecting both membrane leaflets. By measuring the capacitance of peptide-free membranes, as well as their geometrical thicknesses, the dielectric constants in the aliphatic cores of 1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-diphytanoyl-sn-glycero-3-phosphocholine bilayers were determined to be ɛ = 2.8 and 2.2, respectively. The magnitude of the Aβ-induced increase in ɛ indicates that Aβ-oligomers affect membranes by inducing lateral heterogeneity in the bilayers, but an increase in the water content of the bilayers was not observed. The activation energy for Aβ-induced ion transport across the membrane is at least three times higher than that measured for membranes reconstituted with α-hemolysin pores, Ea = 36.8 vs. 9.9 kJ/mol, indicating that the molecular mechanisms underlying both transport processes are fundamentally different. The Aβ-induced membrane conductance shows a nonlinear dependence on the peptide concentration in the membrane. Moreover, Ea depends on

  3. Effect of gamma-ray irradiation at low doses on the performance of PES ultrafiltration membrane

    NASA Astrophysics Data System (ADS)

    Zhang, Xue; Niu, Lixia; Li, Fuzhi; Yu, Suping; Zhao, Xuan; Hu, Hongying

    2016-10-01

    The influence of gamma irradiation on the performance of polyether sulfone (PES) ultrafiltration (UF) membrane was investigated at low absorbed doses (0-75 kGy) using a cobalt source. The performance of the UF membranes was tested using low level radioactive wastewater (LLRW) containing three types of surfactants (anionic, cationic and nonionic surfactants). The physical and chemical properties of membrane surface were analyzed, and relationships between these properties and separation performance and fouling characteristics were determined. At 10-75 kGy irradiation, there were no significant changes observed in the membrane surface roughness or polymer functional groups, however the contact angle decreased sharply from 92° to ca. 70° at irradiation levels as low as 10 kGy. When membranes were exposed to the surfactant-containing LLRW, the flux decreased more sharply for higher dosed irradiated membranes, while flux in virgin membranes increased during the filtration processes. The study highlights that fouling properties of membrane may be changed due to the changes of surface hydrophilicity at low dose irradiation, while other surface properties and retentions remain stable. Therefore, a membrane fouling test with real or simulated wastewater is recommended to fully evaluate the membrane irradiation resistance.

  4. Improved PVDF membrane performance by doping extracellular polymeric substances of activated sludge.

    PubMed

    Guan, Yan-Fang; Huang, Bao-Cheng; Qian, Chen; Wang, Long-Fei; Yu, Han-Qing

    2017-04-15

    Polyvinylidene fluoride (PVDF) membrane has been widely applied in water and wastewater treatment because of its high mechanical strength, thermal stability and chemical resistance. However, the hydrophobic nature of PVDF membrane makes it readily fouled, substantially reducing water flux and overall membrane rejection ability. In this work, an in-situ blending modifier, i.e., extracellular polymeric substances (EPS) from activated sludge, was used to enhance the anti-fouling ability of PVDF membrane. Results indicate that the pure water flux of the membrane and its anti-fouling performance were substantially improved by blending 8% EPS into the membrane. By introducing EPS, the membrane hydrophilicity was increased and the cross section morphology was changed when it interacted with polyvinl pyrrolidone, resulting in the formation of large cavities below the finger-like pores. In addition, the fraction of pores with a size of 100-500 nm increased, which was also beneficial to improving membrane performance. Surface thermodynamic calculations indicate the EPS-functionalized membrane had a higher cohesion free energy, implying its good pollutant rejection and anti-fouling ability. This work provides a simple, efficient and cost-effective method to improve membrane performance and also extends the applications of EPS.

  5. Heat-induced aggregation of thylakoid membranes affect their interfacial properties.

    PubMed

    Östbring, Karolina; Rayner, Marilyn; Albertsson, Per-Åke; Erlanson-Albertsson, Charlotte

    2015-04-01

    Many of our most popular lipid containing foods are in emulsion form. These foods are often highly palatable with high caloric density, that subsequently increases the risk of overconsumption and possibly lead to obesity. Regulating the lipid bioavailability of high-fat foods is one approach to prevent overconsumption. Thylakoids, the chloroplast membrane, creates a barrier around lipid droplets, which prolong lipolysis and increase satiety as demonstrated both in animal and human studies. However, a reduced lipase inhibiting capacity has been reported after heat treatment but the mechanism has not yet been fully established. The aim of this study was to investigate thylakoids' emulsifying properties post heat-treatment and possible links to alterations in lipase inhibiting capacity and chlorophyll degradation. Heat-treatment of thylakoids at either 60 °C, 75 °C or 90 °C for time interval ranging from 15 s to 4 min reduced ability to stabilise emulsions, having increased lipid droplets sizes, reduced emulsification capacity, and elevated surface load as consequence. Emulsifying properties were also found to display a linear relationship to both chlorophyll and lipase inhibiting capacity. The correlations support the hypothesis that heat-treatment induce chlorophyll degradation which promote aggregation within proteins inside the thylakoid membrane known to play a decisive role in interfacial processes. Therefore, heat-treatment of thylakoids affects both chlorophyll content, lipase inhibiting capacity and ability to stabilise the oil-water interface. Since the thylakoid's appetite reducing properties are a surface-related phenomenon, the results are useful to optimize the effect of thylakoids as an appetite reducing agent.

  6. Enhancing performance and surface antifouling properties of polysulfone ultrafiltration membranes with salicylate-alumoxane nanoparticles

    NASA Astrophysics Data System (ADS)

    Mokhtari, Samaneh; Rahimpour, Ahmad; Shamsabadi, Ahmad Arabi; Habibzadeh, Setareh; Soroush, Masoud

    2017-01-01

    To improve the hydrophilicity and antifouling properties of polysulfone (PS) ultrafiltration membranes, we studied the use of salicylate-alumoxane (SA) nanoparticles as a novel hydrophilic additive. The effects of SA nanoparticles on the membrane characteristics and performance were investigated in terms of membrane structure, permeation flux, solute rejection, hydrophilicity, and antifouling ability. The new mixed-matrix membranes (MMMs) possess asymmetric structures. They have smaller finger-like pores and smoother surfaces than the neat PS membranes. The embedment of SA nanoparticles in the polymer matrix and the improvement of surface hydrophilicity were investigated. Ultrafiltration experiments indicated that the pure-water flux of the new MMMs initially increases with SA nanoparticles loading followed by a decrease at high loadings. Higher BSA solution flux was achieved for the MMMs compared to the neat PS membranes. Membranes with 1 wt.% SA nanoparticles exhibit the highest flux recovery ratio of 87% and the lowest irreversible fouling of 13%.

  7. High performance RO membranes for desalination and wastewater reclamation and their operation results.

    PubMed

    Henmi, M; Fusaoka, Y; Tomioka, H; Kurihara, M

    2010-01-01

    Reverse osmosis (RO) membrane is one of the most powerful tools for solving the global water crisis, and is used in a variety of water treatment scenes such as drinking water purification, waste-water treatment, boiler feed water production, ultra pure water production for semiconductor industry, etc. The desired performance of RO membrane varies according to quality of feed water being treated, and Toray has been developing RO membranes with suitable characteristic for each operating condition. RO membranes for seawater desalination and wastewater reclamation are especially regarded as most promising targets. Recently, high boron removal and energy saving RO membrane for seawater desalination and low fouling RO membrane for wastewater reclamation have been developed. In this paper, the prospect of attaining these renovative RO membrane, and furthermore, job references will be discussed.

  8. Magnetization influence on the performance of ferrosoferric oxide: polyacrylonitrile membranes in ultrafiltration of pig blood solution.

    PubMed

    Huang, Zheng-Qing; Guo, Xing-Peng; Guo, Chun-Liang; Zhang, Zhi

    2006-05-01

    Three kinds of membranes were prepared from suspensions containing polyacrylonitrile, dimethyl sulfoxide, polyethylene glycol and different amount of Fe3O4 by the phase inversion process. The rejection rate and the flux of membrane were investigated in the filtration of pig blood solution. SEM also studied the morphologies of fouled membranes. The permeate flux and the rejection rate decline fast in the initial several minutes and then change slowly. The magnetized membrane has a higher flux and a relative flux than the corresponding non-magnetized membrane. And the magnetized membrane containing about 3 wt% Fe3O4 has a prominent anti-fouling performance with above 52% relative flux. The results indicate that the magnetized ferrosoferric oxide-polyacrylonitrile membranes are promising in the recovery of blood proteins in the slaughterhouse effluents. In addition, the hydraulic resistance model explained results and the fouling mechanism was also given.

  9. Impact of colloidal and soluble organic material on membrane performance in membrane bioreactors for municipal wastewater treatment.

    PubMed

    Rosenberger, S; Laabs, C; Lesjean, B; Gnirss, R; Amy, G; Jekel, M; Schrotter, J-C

    2006-02-01

    Two parallel membrane bioreactors (2 m3 each) were operated over a period of 2 years. Both pilots were optimised for nitrification, denitrification, and enhanced biological phosphorous elimination, treating identical municipal wastewater under comparable operating conditions. The only constructional difference between the pilots was the position of the denitrification zone (pre-denitrification in pilot 1 and post-denitrification in pilot 2). Despite identical modules and conditions, the two MBRs showed different permeabilities and fouling rates. The differences were not related to the denitrification scheme. In order to find an explanation for the different membrane performances, a one-year investigation was initiated and the membrane performance as well as the operating regime and characteristics of the activated sludge were closely studied. MLSS concentrations, solid retention time, loading rates, and filtration flux were found not to be responsible for the different performance of the submerged modules. These parameters were kept identical in the two pilot plants. Instead, the non-settable fraction of the sludges (soluble and colloidal material, i.e. polysaccharides, proteins and organic colloids) was found to impact fouling and to cause the difference in membrane performance between the two MBR. This fraction was analysed by spectrophotometric and size exclusion chromatography (SEC) methods. In a second step, the origin of these substances was investigated. The results point to microbiologically produced substances such as extracellular polymeric substances (EPS) or soluble microbial products (SMP).

  10. The science of cycling: factors affecting performance - part 2.

    PubMed

    Faria, Erik W; Parker, Daryl L; Faria, Irvin E

    2005-01-01

    This review presents information that is useful to athletes, coaches and exercise scientists in the adoption of exercise protocols, prescription of training regimens and creation of research designs. Part 2 focuses on the factors that affect cycling performance. Among those factors, aerodynamic resistance is the major resistance force the racing cyclist must overcome. This challenge can be dealt with through equipment technological modifications and body position configuration adjustments. To successfully achieve efficient transfer of power from the body to the drive train of the bicycle the major concern is bicycle configuration and cycling body position. Peak power output appears to be highly correlated with cycling success. Likewise, gear ratio and pedalling cadence directly influence cycling economy/efficiency. Knowledge of muscle recruitment throughout the crank cycle has important implications for training and body position adjustments while climbing. A review of pacing models suggests that while there appears to be some evidence in favour of one technique over another, there remains the need for further field research to validate the findings. Nevertheless, performance modelling has important implications for the establishment of performance standards and consequent recommendations for training.

  11. Lithium-oxygen batteries-Limiting factors that affect performance

    NASA Astrophysics Data System (ADS)

    Padbury, Richard; Zhang, Xiangwu

    2011-05-01

    Lithium-oxygen batteries have recently received attention due to their extremely high theoretical energy densities, which far exceed that of any other existing energy storage technology. The significantly larger theoretical energy density of the lithium-oxygen batteries is due to the use of a pure lithium metal anode and the fact that the cathode oxidant, oxygen, is stored externally since it can be readily obtained from the surrounding air. Before the lithium-oxygen batteries can be realized as high performance, commercially viable products, there are still many challenges to overcome, from designing their cathode structure, to optimizing their electrolyte compositions and elucidating the complex chemical reactions that occur during charge and discharge. The scientific obstacles that are related to the performance of the lithium-oxygen batteries open up an exciting opportunity for researchers from many different backgrounds to utilize their unique knowledge and skills to bridge the knowledge gaps that exist in current research projects. This article is a summary of the most significant limiting factors that affect the performance of the lithium-oxygen batteries from the perspective of the authors. The article indicates the relationships that form between various limiting factors and highlights the complex yet captivating nature of the research within this field.

  12. Direct ultrafiltration performance and membrane integrity monitoring by microbiological analysis.

    PubMed

    Ferrer, O; Casas, S; Galvañ, C; Lucena, F; Bosch, A; Galofré, B; Mesa, J; Jofre, J; Bernat, X

    2015-10-15

    The feasibility of substituting a conventional pre-treatment, consisting of dioxi-chlorination, coagulation/flocculation, settling and sand filtration, of a drinking water treatment plant (DWTP) by direct ultrafiltration (UF) has been assessed from a microbiological standpoint. Bacterial indicators, viral indicators and human viruses have been monitored in raw river, ultrafiltered and conventionally pre-treated water samples during two years. Direct UF has proven to remove bacterial indicators quite efficiently and to a greater extent than the conventional process does. Nevertheless, the removal of small viruses such as some small bacteriophages and human viruses (e.g. enteroviruses and noroviruses) is lower than the current conventional pre-treatment. Membrane integrity has been assessed during two years by means of tailored tests based on bacteriophages with different properties (MS-2, GA and PDR-1) and bacterial spores (Bacillus spores). Membrane integrity has not been compromised despite the challenging conditions faced by directly treating raw river water. Bacteriophage PDR-1 appears as a suitable microbe to test membrane integrity, as its size is slightly larger than the considered membrane pore size. However, its implementation at full scale plant is still challenging due to difficulties in obtaining enough phages for its seeding.

  13. Parents' job insecurity affects children's academic performance through cognitive difficulties.

    PubMed

    Barling, J; Zacharatos, A; Hepburn, C G

    1999-06-01

    The authors developed and tested a model in which children who perceive their parents to be insecure about their jobs are distracted cognitively, which in turn affects their academic performance negatively. Participants were 102 female and 18 male undergraduates (mean age = 18 years), their fathers (mean age = 49 years), and their mothers (mean age = 47 years). Students completed questionnaires measuring perceived parental job insecurity, identification with parents, and cognitive difficulties; 3 months later, they also reported their midyear grades. Fathers and mothers each completed questionnaires assessing their job insecurity. Support for the model was obtained using LISREL 8, and as predicted, children's identification with their mothers and fathers moderated the relationship between their perceptions of their mothers' and fathers' job insecurity and their own cognitive difficulties.

  14. Irrelevant events affect voters' evaluations of government performance

    PubMed Central

    Healy, Andrew J.; Malhotra, Neil; Mo, Cecilia Hyunjung

    2010-01-01

    Does information irrelevant to government performance affect voting behavior? If so, how does this help us understand the mechanisms underlying voters’ retrospective assessments of candidates’ performance in office? To precisely test for the effects of irrelevant information, we explore the electoral impact of local college football games just before an election, irrelevant events that government has nothing to do with and for which no government response would be expected. We find that a win in the 10 d before Election Day causes the incumbent to receive an additional 1.61 percentage points of the vote in Senate, gubernatorial, and presidential elections, with the effect being larger for teams with stronger fan support. In addition to conducting placebo tests based on postelection games, we demonstrate these effects by using the betting market's estimate of a team's probability of winning the game before it occurs to isolate the surprise component of game outcomes. We corroborate these aggregate-level results with a survey that we conducted during the 2009 NCAA men's college basketball tournament, where we find that surprising wins and losses affect presidential approval. An experiment embedded within the survey also indicates that personal well-being may influence voting decisions on a subconscious level. We find that making people more aware of the reasons for their current state of mind reduces the effect that irrelevant events have on their opinions. These findings underscore the subtle power of irrelevant events in shaping important real-world decisions and suggest ways in which decision making can be improved. PMID:20615955

  15. Irrelevant events affect voters' evaluations of government performance.

    PubMed

    Healy, Andrew J; Malhotra, Neil; Mo, Cecilia Hyunjung

    2010-07-20

    Does information irrelevant to government performance affect voting behavior? If so, how does this help us understand the mechanisms underlying voters' retrospective assessments of candidates' performance in office? To precisely test for the effects of irrelevant information, we explore the electoral impact of local college football games just before an election, irrelevant events that government has nothing to do with and for which no government response would be expected. We find that a win in the 10 d before Election Day causes the incumbent to receive an additional 1.61 percentage points of the vote in Senate, gubernatorial, and presidential elections, with the effect being larger for teams with stronger fan support. In addition to conducting placebo tests based on postelection games, we demonstrate these effects by using the betting market's estimate of a team's probability of winning the game before it occurs to isolate the surprise component of game outcomes. We corroborate these aggregate-level results with a survey that we conducted during the 2009 NCAA men's college basketball tournament, where we find that surprising wins and losses affect presidential approval. An experiment embedded within the survey also indicates that personal well-being may influence voting decisions on a subconscious level. We find that making people more aware of the reasons for their current state of mind reduces the effect that irrelevant events have on their opinions. These findings underscore the subtle power of irrelevant events in shaping important real-world decisions and suggest ways in which decision making can be improved.

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  17. Performance of cell-penetrating peptide-linked polymers physically mixed with poorly membrane-permeable molecules on cell membranes.

    PubMed

    Sakuma, Shinji; Suita, Masaya; Yamamoto, Takafumi; Masaoka, Yoshie; Kataoka, Makoto; Yamashita, Shinji; Nakajima, Noriko; Shinkai, Norihiro; Yamauchi, Hitoshi; Hiwatari, Ken-Ichiro; Hashizume, Akio; Tachikawa, Hiroyuki; Kimura, Ryoji; Ishimaru, Yuki; Kasai, Atsushi; Maeda, Sadaaki

    2012-05-01

    We are investigating a new class of penetration enhancers that enable poorly membrane-permeable molecules physically mixed with them to effectively penetrate cell membranes without their concomitant cellular uptake. Since we previously revealed that poly(N-vinylacetamide-co-acrylic acid) modified with d-octaarginine, which is a typical cell-penetrating peptide, significantly enhanced the nasal absorption of insulin, we examined the performance of the polymers on cell membranes. When Caco-2 cells were incubated with 5(6)-carboxyfluorescein (CF) for 30 min, approximately 0.1% of applied CF was internalized into the cells. This poor membrane permeability was dramatically enhanced by d-octaarginine-linked polymers; a 25-fold increase in the cellular uptake of CF was observed when the polymer concentration was adjusted to 0.2mg/mL. None of the individual components, for example, d-octaarginine, had any influence on CF uptake, demonstrating that only d-octaarginine anchored chemically to the polymeric platform enhanced the membrane permeation of CF. The polymer-induced CF uptake was consistently high even when the incubation time was extended to 120 min. Confocal laser scanning microphotographs of cells incubated with d-octaarginine-linked polymers bearing rhodamine red demonstrated that the cell outline was stained with red fluorescence. The polymer-induced CF uptake was significantly suppressed by 5-(N-ethyl-N-isopropyl)amiloride, which is an inhibitor of macropinocytosis. Results indicated that d-octaarginine-linked polymers remained on the cell membrane and poorly membrane-permeable CF was continuously internalized into cells mainly via macropinocytosis repeated for the individual peptidyl branches in the polymer backbone.

  18. Performance of membrane electrode assemblies based on proton exchange membranes prepared by pre-irradiation induced grafting

    NASA Astrophysics Data System (ADS)

    Li, Jingye; Matsuura, Akio; Kakigi, Tomoyuki; Miura, Takaharu; Oshima, Akihiro; Washio, Masakazu

    Proton exchange membranes (PEMs) were prepared by pre-irradiation induced grafting of styrene (S) or styrene/divinylbenzene (S/DVB) into the radiation-crosslinked polytetrafluoroethylene (RX-PTFE) films and then sulfonated. The thicknesses of the obtained PEMs were lower than 20 μm and the ion exchange capacity (IEC) values were around 2 meq g -1. The surfaces of the PEMs and carbon electrodes were coated with Nafion ® dispersion, and then membrane electrode assembles (MEAs) were prepared by hot-pressing them together. A MEA based on a Nafion ® 112 membrane was also prepared under same procedure for comparison. The performances of the MEAs in a single cell were tested under different cell temperatures and humidifications. Electrochemical impedance spectra (EIS) were measured with ac frequencies which ranged from 100 kHz to 1 Hz at a dc density of 0.5 A cm -2. The obtained impedance curves in Nyquist representation were semicircular.

  19. Two coiled-coil domains of Chlamydia trachomatis IncA affect membrane fusion events during infection.

    PubMed

    Ronzone, Erik; Paumet, Fabienne

    2013-01-01

    Chlamydia trachomatis replicates in a parasitophorous membrane-bound compartment called an inclusion. The inclusions corrupt host vesicle trafficking networks to avoid the degradative endolysosomal pathway but promote fusion with each other in order to sustain higher bacterial loads in a process known as homotypic fusion. The Chlamydia protein IncA (Inclusion protein A) appears to play central roles in both these processes as it participates to homotypic fusion and inhibits endocytic SNARE-mediated membrane fusion. How IncA selectively inhibits or activates membrane fusion remains poorly understood. In this study, we analyzed the spatial and molecular determinants of IncA's fusogenic and inhibitory functions. Using a cell-free membrane fusion assay, we found that inhibition of SNARE-mediated fusion requires IncA to be on the same membrane as the endocytic SNARE proteins. IncA displays two coiled-coil domains showing high homology with SNARE proteins. Domain swap and deletion experiments revealed that although both these domains are capable of independently inhibiting SNARE-mediated fusion, these two coiled-coil domains cooperate in mediating IncA multimerization and homotypic membrane interaction. Our results support the hypothesis that Chlamydia employs SNARE-like virulence factors that positively and negatively affect membrane fusion and promote infection.

  20. Ankyrin and band 3 differentially affect expression of membrane glycoproteins but are not required for erythroblast enucleation

    SciTech Connect

    Ji, Peng; Lodish, Harvey F.

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Ankyrin and band 3 are not required for erythroblasts enucleation. Black-Right-Pointing-Pointer Loss of ankyrin does not affect erythroid membrane glycoprotein expression. Black-Right-Pointing-Pointer Loss of band 3 influences erythroid membrane glycoprotein expression. -- Abstract: During late stages of mammalian erythropoiesis the nucleus undergoes chromatin condensation, migration to the plasma membrane, and extrusion from the cytoplasm surrounded by a segment of plasma membrane. Since nuclear condensation occurs in all vertebrates, mammalian erythroid membrane and cytoskeleton proteins were implicated as playing important roles in mediating the movement and extrusion of the nucleus. Here we use erythroid ankyrin deficient and band 3 knockout mouse models to show that band 3, but not ankyrin, plays an important role in regulating the level of erythroid cell membrane proteins, as evidenced by decreased cell surface expression of glycophorin A in band 3 knockout mice. However, neither band 3 nor ankyrin are required for enucleation. These results demonstrate that mammalian erythroblast enucleation does not depend on the membrane integrity generated by the ankyrin-band 3 complex.

  1. A model-based parametric analysis of a direct ethanol polymer electrolyte membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Andreadis, G. M.; Podias, A. K. M.; Tsiakaras, P. E.

    In the present work, a model-based parametric analysis of the performance of a direct ethanol polymer electrolyte membrane fuel cell (DE-PEMFC) is conducted with the purpose to investigate the effect of several parameters on the cell's operation. The analysis is based on a previously validated one-dimensional mathematical model that describes the operation of a DE-PEMFC in steady state. More precisely, the effect of several operational and structural parameters on (i) the ethanol crossover rate from the anode to the cathode side of the cell, (ii) the parasitic current generation (mixed potential formation) and (iii) the total cell performance is investigated. According to the model predictions it was found that the increase of the ethanol feed concentration leads to higher ethanol crossover rates, higher parasitic currents and higher mixed potential values resulting in the decrease of the cell's power density. However there is an optimum ethanol feed concentration (approximately 1.0 mol L -1) for which the cell power density reaches its highest value. The platinum (Pt) loading of the anode and the cathode catalytic layers affects strongly the cell performance. Higher values of Pt loading of the catalytic layers increase the specific reaction surface area resulting in higher cell power densities. An increase of the anode catalyst loading compared to an equal one of the cathode catalyst loading has greater impact on the cell's power density. Another interesting finding is that increasing the diffusion layers' porosity up to a certain extent, improves the cell power density despite the fact that the parasitic current increases. This is explained by the fact that the reactants' concentrations over the catalysts are increased, leading to lower activation overpotential values, which are the main source of the total cell overpotentials. Moreover, the use of a thicker membrane leads to lower ethanol crossover rate, lower parasitic current and lower mixed potential values

  2. Performance comparison of long and short-side chain perfluorosulfonic membranes for high temperature polymer electrolyte membrane fuel cell operation

    NASA Astrophysics Data System (ADS)

    Stassi, A.; Gatto, I.; Passalacqua, E.; Antonucci, V.; Arico, A. S.; Merlo, L.; Oldani, C.; Pagano, E.

    A new Aquivion™ E79-03S short-side chain perfluorosulfonic membrane with a thickness of 30 μm (dry form) and an equivalent weight (EW) of 790 g/equiv recently developed by Solvay-Solexis for high-temperature operation was tested in a pressurised (3 bar abs.) polymer electrolyte membrane (PEM) single cell at a temperature of 130 °C. For comparison, a standard Nafion™ membrane (EW 1100 g/equiv) of similar thickness (50 μm) was investigated under similar operating conditions. Both membranes were tested for high temperature operation in conjunction with an in-house prepared carbon supported Pt electrocatalyst. The electrocatalyst consisted of nanosized Pt particles (particle size ∼2 nm) dispersed on a high surface area carbon black. The electrochemical tests showed better performance for the Aquivion™ membrane as compared to Nafion™ with promising properties for high temperature PEM fuel cell applications. Beside the higher open circuit voltage and lower ohmic constraints, a higher electrocatalytic activity was observed at high temperature for the electrocatalyst-Aquivion™ ionomer interface indicating a better catalyst utilization.

  3. LRRK2 Affects Vesicle Trafficking, Neurotransmitter Extracellular Level and Membrane Receptor Localization

    PubMed Central

    Spissu, Ylenia; Sanna, Giovanna; Xiong, Yulan; Dawson, Ted M.; Dawson, Valina L.; Galioto, Manuela; Rocchitta, Gaia; Biosa, Alice; Serra, Pier Andrea; Carri, Maria Teresa; Crosio, Claudia; Iaccarino, Ciro

    2013-01-01

    The leucine-rich repeat kinase 2 (LRRK2) gene was found to play a role in the pathogenesis of both familial and sporadic Parkinson’s disease (PD). LRRK2 encodes a large multi-domain protein that is expressed in different tissues. To date, the physiological and pathological functions of LRRK2 are not clearly defined. In this study we have explored the role of LRRK2 in controlling vesicle trafficking in different cellular or animal models and using various readouts. In neuronal cells, the presence of LRRK2G2019S pathological mutant determines increased extracellular dopamine levels either under basal conditions or upon nicotine stimulation. Moreover, mutant LRRK2 affects the levels of dopamine receptor D1 on the membrane surface in neuronal cells or animal models. Ultrastructural analysis of PC12-derived cells expressing mutant LRRK2G2019S shows an altered intracellular vesicle distribution. Taken together, our results point to the key role of LRRK2 to control vesicle trafficking in neuronal cells. PMID:24167564

  4. Performance of an anaerobic membrane bioreactor for pharmaceutical wastewater treatment.

    PubMed

    Svojitka, Jan; Dvořák, Lukáš; Studer, Martin; Straub, Jürg Oliver; Frömelt, Heinz; Wintgens, Thomas

    2017-04-01

    Anaerobic treatment of wastewater and waste organic solvents originating from the pharmaceutical and chemical industries was tested in a pilot anaerobic membrane bioreactor, which was operated for 580days under different operational conditions. The goal was to test the long-term treatment efficiency and identify inhibitory factors. The highest COD removal of up to 97% was observed when the influent concentration was increased by the addition of methanol (up to 25gL(-1) as COD). Varying and generally lower COD removal efficiency (around 78%) was observed when the anaerobic membrane bioreactor was operated with incoming pharmaceutical wastewater as sole carbon source. The addition of waste organic solvents (>2.5gL(-1) as COD) to the influent led to low COD removal efficiency or even to the breakdown of anaerobic digestion. Changes in the anaerobic population (e.g., proliferation of the genus Methanosarcina) resulting from the composition of influent were observed.

  5. High Performance Immobilized Liquid Membrane for Carbon Dioxide Separations

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2005-01-01

    An immobilized liquid membrane has a substrate. A plurality of capsules is disposed on the substrate. Each of the capsules is permeable to a first gas of a mixture of gases comprising the st gas and a second gas. Each of the capsules is substantially impermeable to the second gas. A liquid is disposed in each of the capsules that is permeable to the first gas and substantially impermeable to the second gas.

  6. Effects of salinity build-up on the performance and bacterial community structure of a membrane bioreactor.

    PubMed

    Luo, Wenhai; Phan, Hop V; Hai, Faisal I; Price, William E; Guo, Wenshan; Ngo, Hao H; Yamamoto, Kazuo; Nghiem, Long D

    2016-01-01

    This study investigated the effects of salinity increase on bacterial community structure in a membrane bioreactor (MBR) for wastewater treatment. The influent salt loading was increased gradually to simulate salinity build-up in the bioreactor during the operation of a high retention-membrane bioreactor (HR-MBR). Bacterial community diversity and structure were analyzed using 454 pyrosequencing of 16S rRNA genes of MBR mixed liquor samples. Results show that salinity increase reduced biological performance but did not affect microbial diversity in the bioreactor. Unweighted UniFrac and taxonomic analyses were conducted to relate the reduced biological performance to the change of bacterial community structure. In response to the elevated salinity condition, the succession of halophobic bacteria by halotolerant/halophilic microbes occurred and thereby the biological performance of MBR was recovered. These results suggest that salinity build-up during HR-MBR operation could be managed by allowing for the proliferation of halotolerant/halophilic bacteria.

  7. Analyte loss due to membrane filter adsorption as determined by high-performance liquid chromatography.

    PubMed

    Carlson, M; Thompson, R D

    2000-02-01

    The phenomenon of membrane filter adsorption in high-performance liquid chromatography (HPLC) is investigated utilizing 16 brands of filters representing 3 polymeric materials: cellulose acetate (CA), nylon, and polyvinylidene difluoride in a variety of diameters (3, 4, 7, 13, and 25 mm). Sixteen compounds commonly encountered in drug preparations are selected as sample analytes and classified as acidic, basic, and neutral in chemical behavior. Six mobile phase/sample solvent mixtures are included: 3 with methanol-water and 3 with acetonitrile-water as major constituents. When using methanol as the mobile phase organic component, CA, nylon, and polyvinylidene difluoride (PVDF) filters exhibit negligible to moderate adsorption levels with regard to the neutral and basic drug compounds. The acidic drug test compounds are adsorbed by 50% of all 3 filter materials tested in methanol-water. In acetonitrile, neutral compounds are affected by 31.4%, basic compounds are affected by 47.0%, and acidic compounds are affected by 53.6% of the nylon and PVDF filters. CA is incompatible with acetonitrile and is excluded from the study with this solvent.

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

    NASA Astrophysics Data System (ADS)

    Aziz, Md. Abdul; Shanmugam, Sangaraju

    2017-01-01

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

  9. High performance radiation-grafted membranes and electrodes for polymer electrolyte fuel cells

    SciTech Connect

    Nezu, Shinji; Seko, Hideo; Gondo, Masaki; Ito, Naoki

    1996-12-31

    Polymer electrolyte fuel cells (PEFC) have attracted much attention for stationary and electric vehicle applications. Much progress has been made to improve their performance recently. However there are still several problems to overcome for commercialization. Among them, the cost of polymer electrolyte membranes seems to be rather critical, because a cost estimate of a practical fuel cell stack shows that the membrane cost must be reduced at least by two orders of magnitude based on current perfluorosulfonic acid membranes eg. Nafion{reg_sign}. Thus the development of new membrane materials is strongly desired. Styrene grafted tetrafluoroethylene-hexafluoropropylene copolymer (FEP) membranes have been studied for a fuel cell application by G. Scherer et al. These authors showed that membranes obtained by radiation grafting served as an alternative membrane for fuel cells although there were several problems to overcome in the future. These problems include shorter life time which was concluded to result from the decomposition of grafted polystyrene side chains. We report here the performance of our fuel cells which were fabricated from our radiation grafted membranes (IMRA MEMBRANE) and gas diffusion electrodes.

  10. Influence of Brij58 on the Characteristic and Performance of PES Membrane for Water Treatment Process

    NASA Astrophysics Data System (ADS)

    Mukramah; Syawaliah; Mulyati, S.; Arahman, N.

    2017-03-01

    This study proposes a modification of polyether sulfone (PES) membrane by blending the polymer with a hydrophilic additive of Brij-58. Flat-sheet PES membrane was prepared through a non-solvent induced phase separation (NIPS) method using dimethylformamide (DMF) as a solvent. PES membrane was modified by adding Brij-58 into dope solution at a different concentration, i.e 1, 3, 5, 7, and 10 wt %. The fabricated membranes were characterized by means of Scanning Electron Microscopy (SEM) and Fourier Transform Infra-Red (FTIR) spectroscopy. Filtration performance of membrane was analyzed by using a dead-end module. It is found that the addition of a small amount of Brij into polymer solution brought about the increase of water flux. FT-IR investigation showed that the additive exist on the surface of a blended membrane.

  11. Development of a novel Submerged Membrane Electro-Bioreactor (SMEBR): performance for fouling reduction.

    PubMed

    Bani-Melhem, Khalid; Elektorowicz, Maria

    2010-05-01

    A novel Submerged Membrane Electro-Bioreactor (SMEBR) was developed to treat wastewater and control the problem of membrane fouling. To validate the new design, experimental work was achieved in a few phases. This paper describes the design constraints and criteria of the new developed SMEBR system, and shows the results of the performance of the SMEBR system to reduce membrane fouling when intermittent direct current (DC) (15 min ON/45 min OFF) was applied using cylindrical iron mesh for both electrodes. Application of the SMEBR system enhanced the membrane filterability by reducing the fouling rate up to 16.3% without any backwashing of the membrane module. The improvement in membrane filterability associated with a decrease in zeta potential of the mixed liquor flocs from -30.5 up to -15.3 mV and a decrease in specific resistance to filtration (SRF) up to 40% was observed.

  12. Effect of deacetylation degree in chitosan composite membranes on pervaporation performance

    SciTech Connect

    Lee, Y.M.; Park, H.B.; Nam, S.Y.; Won, J.M.; Kim, H.

    1998-06-01

    The effect of the degree of deacetylation in chitosan composite membranes on their pervaporation performance for ethanol dehydration was investigated. The degree of deacetylation of chitosans was measured by using an infrared spectroscopic method and elemental analysis. The chitosan composite membranes were prepared by coating a chitosan solution onto a microporous polyethersulfone membrane with 3--7 nm pore sizes. Then the surface of the top layer (chitosan) of well-dried membranes was crosslinked with sulfuric acid, and pervaporation experiments for binary mixtures (water-ethanol) were carried out at various conditions. In the case of a chitosan membrane with a high degree of deacetylation, the flux increases while the separation factor decreases compared with membranes with a low degree of deacetylation.

  13. Facile surface modification of anion-exchange membranes for improvement of diffusion dialysis performance.

    PubMed

    Kim, Do-Hyeong; Park, Han-Sol; Seo, Seok-Jun; Park, Jin-Soo; Moon, Seung-Hyeon; Choi, Young-Woo; Jiong, Young Su; Kim, Dong Hee; Kang, Moon-Sung

    2014-02-15

    In this study, a facile membrane modification method by spin-coating of pyrrole (Py) monomers dissolved in a volatile solvent followed by an interfacial polymerization is proposed. The surface of a commercial anion-exchange membrane (i.e., Neosepta-AFX, Astom Corp., Japan) was successfully modified with polypyrrole (Ppy) to improve the acid recovery performance in diffusion dialysis (DD). The result of DD experiments revealed that both the acid and metal ion transports are significantly influenced by the surface modification. The metal crossover through the membranes was largely reduced while mostly maintaining the acid permeability by introducing a thin Ppy layer with excellent repelling property to cations on the membrane surface. As a result, the anion-exchange membrane modified with the optimum content of Py monomer (5 vol.%) exhibited excellent acid dialysis coefficient (KAcid) and selectivity (KAcid/KMetal) which is approximately twice as high as that of the pristine membrane.

  14. Relative Age Affects Marathon Performance in Male and Female Athletes

    PubMed Central

    Connick, Mark J.; Beckman, Emma M.; Tweedy, Sean M.

    2015-01-01

    Marathon runners are ranked in 5-year age groups. However the extent to which 5-year groupings facilitates equitable competition has not been evaluated. The aim of this study was to evaluate the effect of relative age in male and female marathon running. Marathon finishing times for the top ten male (aged 20-69 years) and female athletes (aged 20-64 years) were obtained from the 2013 New York and Chicago marathons. Intra-class and inter-class validity were evaluated by comparing performances within (intra-class) and between (inter-class) the 5-year age groups. Results showed intra-class effects in all male age groups over 50 years, in all female age groups over 40 years, and in male and female 20-24 age groups (p < 0.05). Inter-class differences existed between the 20-24 and 25-29 age groups in both males and females, between all male age groups over 50 years, and between all female age groups over 40 years (p < 0.05). This study provided the first evaluation of the effects of relative age in male and female marathon running. The results provide preliminary but compelling evidence that the relatively older male athletes in age groups over 50 years and the relatively older females in age groups over 40 years are competitively disadvantaged compared to the younger athletes in these age groups. Key points Results showed a curvilinear relationship between age and marathon running performance with the negative effect of age becoming more pronounced in older runners. Relative age effects were found in all age groups over age 50 years in males and over age 40 years in females indicating that the relatively older runners were competitively disadvantaged compared to the relatively younger runners in these age groups. Relative age affected the 20-24 age classification which is consistent with the hypothesis that marathon performance improves until peak performance occurs in the 25-29 age classification. PMID:26336355

  15. Relative Age Affects Marathon Performance in Male and Female Athletes.

    PubMed

    Connick, Mark J; Beckman, Emma M; Tweedy, Sean M

    2015-09-01

    Marathon runners are ranked in 5-year age groups. However the extent to which 5-year groupings facilitates equitable competition has not been evaluated. The aim of this study was to evaluate the effect of relative age in male and female marathon running. Marathon finishing times for the top ten male (aged 20-69 years) and female athletes (aged 20-64 years) were obtained from the 2013 New York and Chicago marathons. Intra-class and inter-class validity were evaluated by comparing performances within (intra-class) and between (inter-class) the 5-year age groups. Results showed intra-class effects in all male age groups over 50 years, in all female age groups over 40 years, and in male and female 20-24 age groups (p < 0.05). Inter-class differences existed between the 20-24 and 25-29 age groups in both males and females, between all male age groups over 50 years, and between all female age groups over 40 years (p < 0.05). This study provided the first evaluation of the effects of relative age in male and female marathon running. The results provide preliminary but compelling evidence that the relatively older male athletes in age groups over 50 years and the relatively older females in age groups over 40 years are competitively disadvantaged compared to the younger athletes in these age groups. Key pointsResults showed a curvilinear relationship between age and marathon running performance with the negative effect of age becoming more pronounced in older runners.Relative age effects were found in all age groups over age 50 years in males and over age 40 years in females indicating that the relatively older runners were competitively disadvantaged compared to the relatively younger runners in these age groups.Relative age affected the 20-24 age classification which is consistent with the hypothesis that marathon performance improves until peak performance occurs in the 25-29 age classification.

  16. Factors affecting student performance in an undergraduate genetics course.

    PubMed

    Bormann, J Minick; Moser, D W; Bates, K E

    2013-05-01

    The objective of this study was to determine some of the factors that affect student success in a genetics course. Genetics for the Kansas State University College of Agriculture is taught in the Department of Animal Sciences and Industry and covers Mendelian inheritance, molecular genetics, and quantitative/population genetics. Data collected from 1,516 students over 7 yr included year and semester of the course; age; gender; state of residence; population of hometown; Kansas City metro resident or not; instructor of course; American College Testing Program (ACT) scores; number of transfer credits; major; college; preveterinary student or not; freshman, sophomore, junior, and senior grade point average (GPA); semester credits when taking genetics; class standing when enrolled in genetics; cumulative GPA before and after taking genetics; semester GPA in semester taking genetics, number of semesters between the biology prerequisite and genetics; grade in biology; location of biology course; and final percentage in genetics. Final percentage in genetics did not differ due to instructor, gender, state of residence, major, or college (P > 0.16). Transfer students tended to perform better than nontransfer students (P = 0.09), and students from the Kansas City metro outscored students from other areas (P = 0.03). Preveterinary option students scored higher in genetics than non-preveterinary students (P < 0.01). Seniors scored higher than juniors and sophomores, who scored higher than freshmen (P < 0.02). We observed a tendency for students with higher grades in biology to perform better in genetics (P = 0.06). Students who took biology at Kansas State University performed better in genetics than students who transferred the credit (P < 0.01). There was a negative regression of hometown population on score in genetics (P < 0.01), and positive regressions of ACT score, all measures of GPA, course load, and cumulative credits on final percentage in the course (P < 0.02). To

  17. Alkali doped poly (2,5-benzimidazole) membrane for alkaline water electrolysis: Characterization and performance

    NASA Astrophysics Data System (ADS)

    Diaz, Liliana A.; Hnát, Jaromír; Heredia, Nayra; Bruno, Mariano M.; Viva, Federico A.; Paidar, Martin; Corti, Horacio R.; Bouzek, Karel; Abuin, Graciela C.

    2016-04-01

    The properties and performance of linear and cross-linked KOH doped ABPBI membranes as electrolyte/separator for zero gap alkaline water electrolysis cells are evaluated and compared with a commercial Zirfon® diaphragm. Stability in alkaline environment, swelling, thermal properties, water sorption, KOH uptake and conductivity of linear (L-ABPBI) and cross-linked (C-ABPBI) membranes doped with different concentrations of KOH are analyzed. Linear membranes show stability up to 3.0 mol·dm-3 KOH doping, while cross-linked membranes are stable up to 4.2 mol·dm-3 KOH doping. Both kinds of membranes exhibit good thermal stability and reasonable specific ionic conductivity at 22 °C in the range between 7 and 25 mS·cm-1, being slightly higher the conductivity of C-ABPBI membranes than that of L-ABPBI ones. In short-term electrolysis tests both L-ABPBI and C-ABPBI membranes show better performance than Zirfon diaphragm in the range from 50 to 70 °C. A current density of 335 mA·cm-2 at a cell voltage of 2.0 V is attained with C-ABPBI membranes doped in 3 mol·dm-3 KOH at 70 °C, a performance comparable with that of commercial units operating at temperatures ca. 80 °C and 30 wt% KOH (6.7 mol·dm-3) as electrolyte.

  18. Improved performance of single-chamber microbial fuel cells through control of membrane deformation.

    PubMed

    Zhang, Xiaoyuan; Cheng, Shaoan; Huang, Xia; Logan, Bruce E

    2010-03-15

    Cation (CEMs) and anion exchange membrane (AEMs) are commonly used in microbial fuel cells (MFCs) to enhance Coulombic efficiencies (CEs) by reducing the flux of oxygen through the cathode to bacteria on the anode. AEMs typically work better than CEMs, but in initial experiments we observed the opposite using a membrane electrode assembly MFC. The reason was identified to be membrane deformation, which resulted in water and gas trapped between the membrane and cathode. To correct this, stainless steel mesh was used to press the membrane flat against the cathode. With the steel mesh, AEM performance increased to 46+/-4 W/m(3) in a single cathode MFC, and 98+/-14 W/m(3) in a double-cathode MFC. These power densities were higher than those using a CEM of 32+/-2 W/m(3) (single cathode) and 63+/-6 W/m(3) (double cathode). Higher pH gradients across the membrane and salt precipitation on the cathode were responsible for the reduced performance of the CEM compared to the AEM. CEs reached over 90% for both membranes at >2A/m(2). These results demonstrate the importance of avoiding water accumulation in thin films between membranes and electrodes, and explain additional reasons for poorer performance of CEMs compared to AEMs.

  19. Performance evaluation of cross-flow membrane system for wastewater reuse from the wood-panels industry.

    PubMed

    Dizge, Nadir

    2014-01-01

    The objectives of this investigation were to perform a series of lab-scale membrane separation experiments under various operating conditions to investigate the performance behaviour of nanofiltration membrane (NF 270) for wastewater reuse from the wood-panels industry. The operating condition effects, e.g. cross-flow velocity (CFV), trans membrane pressure (TMP) and temperature, on the permeate flux and contaminant rejection efficiency were investigated. Moreover, three different samples: (1) raw wastewater collected from the wood-panels industry; (2) ultrafiltration pre-treated wastewater (UF-NF); and (3) coagulation/flocculation pre-treated wastewater (CF-NF) were employed in this study. The UF-NF was proposed as a pre-treatment process because it could reduce the chemical oxygen demand (COD) effectively with lower energy consumption than CF-NF. The performance of NF 270 membrane was assessed by measurements of the many parameters (pH, conductivity, total dissolved solids, COD, suspended solids, total nitrogen, nitrite, nitrate, and total phosphate) under various operating conditions. It was noted that the contaminant rejection was affected by changing TMP and CFV. It was concluded that the purified water stream can be recycled into the process for water reuse or safely disposed to the river.

  20. Evaluation of dialyzer jacket structure and hollow-fiber dialysis membranes to achieve high dialysis performance.

    PubMed

    Hirano, Ayaka; Yamamoto, Ken-ichiro; Matsuda, Masato; Ogawa, Takehito; Yakushiji, Taiji; Miyasaka, Takehiro; Sakai, Kiyotaka

    2011-02-01

    The objective of this study was to determine the optimum dialyzer jacket structure and hollow-fiber dialysis membrane, both of which are indispensable factors for achieving high dialysis performance, by clarifying the relationship between the dialysis performance and the flow of dialysate and blood in a hollow-fiber dialyzer. We evaluated the clearance, dialysate, and blood flow for four commercially available hollow-fiber dialyzers, namely, the APS-15S, APS-15SA, TS-1.6UL, and CX-1.6U. To evaluate dialysate and blood flow, we measured the residence-time distribution of dialysate and blood flow of these dialyzers by the pulse-response method. We also determined the clearances of urea, creatinine, vitamin B(12), and lysozyme to evaluate the dialysis performance of these dialyzers. While the baffle and taper structures allow effective supply of dialysate into the dialyzer jacket, the hollow-fiber shape, inner diameter, and packing density significantly influence the dialysate flow. In dialyzers with long taper-holding slits, the slit area is a key design parameter for achieving optimum dialysate flow. Similarly, the blood flow is significantly influenced by the structure of the inflowing and outflowing blood ports at the header of a dialyzer, and the shape and inner diameter of the hollow fibers. Hollow fibers with smaller inner diameters cause an increase in blood pressure, which causes blood to enter the hollow fibers more easily. The hollow-fiber shape hardly affects the blood flow. While improved dialysate and blood flow cause higher clearance of low molecular-weight substances, higher membrane area and pure-water permeability accelerate internal filtration, thereby causing an increase in the clearance of large molecular-weight substances.

  1. Effect of polyethersulfone concentration on flat and hollow fiber membrane performance

    SciTech Connect

    Wood, H.; Wang, J. ); Sourirajan, S. )

    1993-11-01

    Flat and hollow fiber (HF) membranes are made in order to determine the effect of the polyethersulfone (PES) concentration in the precursor film-casting solution on the resultant flat and hollow fiber membrane performance. The additive polyvinylpyrrolidone (PVP) is included in the film-casting solution to ensure that membranes can be made over wide variations in the PES polymer concentration. In general, membrane permeability decreases and solute separation ability increases as the PES concentration increases. However, for both flat and HF membranes, performance is strongly dependent on whether the PES concentration is above or below the critical value. Flux greatly decreases and solute-separation ability increases when the critical PES concentration is at the critical value. 20 refs., 1 fig., 4 tabs.

  2. Common α2A and α2C adrenergic receptor polymorphisms do not affect plasma membrane trafficking.

    PubMed

    Hurt, Carl M; Sorensen, Matt W; Angelotti, Timothy

    2014-06-01

    Various naturally occurring polymorphic forms of human G protein-coupled receptors (GPCRs) have been identified and linked to diverse pathological diseases, including receptors for vasopressin type 2 (nephrogenic diabetes insipidus) and gonadotropin releasing hormone (hypogonadotropic hypogonadism). In most cases, polymorphic amino acid mutations disrupt protein folding, altering receptor function as well as plasma membrane expression. Other pathological GPCR variants have been found that do not alter receptor function, but instead affect only plasma membrane trafficking (e.g., delta opiate and histamine type 1 receptors). Thus, altered membrane trafficking with retained receptor function may be another mechanism causing polymorphic GPCR dysfunction. Two common human α2A and α2C adrenergic receptor (AR) variants have been identified (α2A N251K and α2C Δ322-325 ARs), but pharmacological analysis of ligand binding and second messenger signaling has not consistently demonstrated altered receptor function. However, possible alterations in plasma membrane trafficking have not been investigated. We utilized a systematic approach previously developed for the study of GPCR trafficking motifs and accessory proteins to assess whether these α2 AR variants affected intracellular trafficking or plasma membrane expression. By combining immunofluorescent microscopy, glycosidic processing analysis, and quantitative fluorescent-activated cell sorting (FACS), we demonstrate that neither variant receptor had altered intracellular localization, glycosylation, nor plasma membrane expression compared to wild-type α2 ARs. Therefore, pathopharmacological properties of α2A N251K and α2C Δ322-325 ARs do not appear to be due to altered receptor pharmacology or plasma membrane trafficking, but may involve interactions with other intracellular signaling cascades or proteins.

  3. How does γ-irradiation affect the properties of a microfiltration membrane constituted of two polymers with different radiolytic behavior?

    NASA Astrophysics Data System (ADS)

    Fortin, Nicolas; Albela, Belén; Bonneviot, Laurent; Rouif, Sophie; Sanchez, Jean-Yves; Portinha, Daniel; Fleury, Etienne

    2012-03-01

    The objective of this work is to present the behavior of a fluorinated microporous membrane composed of poly(vinylidene fluoride) (PVDF) mechanically reinforced by a polyamide-66 (PA-66) fabric under γ-irradiation with dose ranging between 0 and 100 kGy, in inert atmosphere and at room temperature. Particular attention was paid to the evolution of mechanical properties, the surface morphology and pores size distribution of this membrane, in order to study the filtration capacity and selectivity with increasing radiation dose. Moreover, the repartition of the generated radicals onto the two components of the membrane was achieved by electron spin resonance (ESR) spectroscopy. Two different regimes are observed depending on the dose range, and a correlation between the mechanical behavior of the membrane and the evolution of the concentration of the radicals in the PA fabric is observed. Globally, the porosity of the surface membrane does not vary whatever the dose may be, but the mechanical properties of the membrane as well as the permeability are strongly affected, even for low radiation dose such as 10 kGy. These results are related to chain scissions on the PA fabric, which occurred preferentially, compared to cross-linking, in the investigated dose range.

  4. Influence of poly(ethylene glycol) as pore-generator on morphology and performance of chitosan/poly(vinyl alcohol) membrane adsorbents

    NASA Astrophysics Data System (ADS)

    Salehi, E.; Madaeni, S. S.

    2014-01-01

    Macroporous chitosan/poly(vinyl alcohol) membrane adsorbents were synthesized by solvent evaporation in the presence of poly(ethylene glycol) which was utilized as porogen. The membranes were applied for Cu(II) ion adsorption from water. SEM, AFM and wettability analyses were performed for membrane characterization. Insertion of poly(ethylene glycol) generated macrovoids in the dense structure of CS/PVA membranes through particulate leaching out mechanism. According to the static adsorption tests, the uptake capacity of the porous membranes is elevated (∼26 mg/g) compared to that of the dense membranes (∼10 mg/g). This phenomenon is attributed to the increase in the density of active sites, water affinity and surface roughness as a result of the porogen effects. The approachability of the ions to the active sites was also affected by these important parameters. Both size and density of the macrovoids increased with increasing PEG content from nil to 5 wt%. Fragility of the resultant porous structures prohibited synthesizing CS/PVA membranes with higher porogen contents. Desorption tests showed that the porous membranes were better regenerated in comparison to the dense membranes using Na2EDTA as eluant. Generally, the results suggested that the CS/PVA membranes, comprising PEG as pore-generator agent, are potential candidates for adsorption and elimination of Cu(II) ions from water.

  5. Launch Conditions Might Affect the Formation of Blood Vessel in the Quail Chorioallantoic Membrane

    NASA Technical Reports Server (NTRS)

    Henry, M. K.; Unsworth, B. R.; Sychev, B. R.; Guryeva, T. S.; Dadasheva, O. A.; Piert, S. J.; Lagel, K. E.; Dubrovin, L. C.; Jahns, G. C.; Boda, K.; Sabo, V.; Samet, M. M.; Lelkes, P. I.

    1998-01-01

    AS 2 part of the first joint USA-Russian MIR/Shuttle program, fertilized quail eggs were flown on the MIR 18 mission. Post-flight examination indicated impaired survival of both the embryos in space and also of control embryos exposed to vibrational and g-forces simulating the conditions experienced during the launch of Progress 227. We hypothesized that excess mechanical forces and/or other conditions during the launch might cause abnormal development of the blood supply in the chorioallantoic membrane (CAM) leading to the impaired survival of the embryos. The CAM, a highly vascularized extraembryonic organ, provides for the oxygen exchange across the egg shell and is thus pivotal for proper embryonic development. To test our hypothesis, we compared angiogenesis In CAMS of eggs which were either exposed to the vibration and g-force profile simulating the conditions at launch of Progress 227 (synchronous controls), or kept under routine conditions in a laboratory Incubator (laboratory controls). At various time points during Incubation, the eggs were fixed in paraformaldehyde for subsequent dissection. At the time of dissection, the CAM was carefully lifted from the egg shell and examined as whole mounts by bright-field and fluorescent microscopy. The development or the vasculature (angiogenesis) was assessed from the density of blood vessels per viewing field and evaluated by computer aided image analysis. We observed a significant decrease In blood-vessel density in the synchronous controls versus "normal" laboratory controls beginning from day 10 of Incubation. The decrease in vascular density was restricted to the smallest vessels only, suggesting that conditions during the launch and/or during the subsequent Incubation of the eggs may affect the normal progress of angiogenesis in the CAM. Abnormal angiogenesis In the CAM might contribute to the impaired survival of the embryos observed in synchronous controls as well as in space.

  6. Factors affecting seasonal variation of membrane filtration resistance caused by Chlorella algae.

    PubMed

    Babel, Sandhya; Takizawa, Satoshi; Ozaki, Hiroaki

    2002-03-01

    A seasonal fluctuation pattern was observed in membrane filtration resistance by Chlorella algae cultured in open ponds in the tropical environment. In order to investigate the causes of this phenomenon, Chlorella was cultivated under controlled conditions and the cake resistance was measured by batch filtration in dead-end mode. The filtration resistance was found to be a function of environmental conditions. Algae could grow favourably and offered low specific cake resistance (R,s) on the order of 10(11) m/g for the culture temperature from 28 degrees C to 35 degrees C. The algal growth was inhibited and the specific cake resistance increased to the order of 10(12) m/g below or above this optimum temperature range. Strong solar radiation, coupled with high temperatures, also inhibited the growth of algae and resulted in higher specific cake resistance. The specific cake resistance of algae cultured at different temperatures increased with the amount of the extracellular organic matter (EOM) extracted by 0.1 N NaOH. Hence EOM, rather than bacteria present in the mono-algal culture, was considered to be the primary factor affecting the cake resistance. The specific cake resistance increased drastically after actively growing cells were stored in nutrient-free water under dark conditions. However, the resistance was slightly decreased when the algal cells were stored in NSIII nutrient media in a dark room, indicating the effect of nutrient availability on the change of the specific cake resistance under the light-limiting conditions. EOM extracted from the cells kept in the nutrient-free water contained less sugar than the fresh culture, whereas the EOM extracted from the cells stored in the NSIII media contained more sugar. The molecular distribution of the EOM shifted from below 1,000 kDa before storage to more than 2,000 kDa after storage in both the nutrient-free and NSIII media.

  7. Potential electrostatic interactions in multiple regions affect human metapneumovirus F-mediated membrane fusion.

    PubMed

    Chang, Andres; Hackett, Brent A; Winter, Christine C; Buchholz, Ursula J; Dutch, Rebecca Ellis

    2012-09-01

    The recently identified human metapneumovirus (HMPV) is a worldwide respiratory virus affecting all age groups and causing pneumonia and bronchiolitis in severe cases. Despite its clinical significance, no specific antiviral agents have been approved for treatment of HMPV infection. Unlike the case for most paramyxoviruses, the fusion proteins (F) of a number of strains, including the clinical isolate CAN97-83, can be triggered by low pH. We recently reported that residue H435 in the HRB linker domain acts as a pH sensor for HMPV CAN97-83 F, likely through electrostatic repulsion forces between a protonated H435 and its surrounding basic residues, K295, R396, and K438, at low pH. Through site-directed mutagenesis, we demonstrated that a positive charge at position 435 is required but not sufficient for F-mediated membrane fusion. Arginine or lysine substitution at position 435 resulted in a hyperfusogenic F protein, while replacement with aspartate or glutamate abolished fusion activity. Studies with recombinant viruses carrying mutations in this region confirmed its importance. Furthermore, a second region within the F(2) domain identified as being rich in charged residues was found to modulate fusion activity of HMPV F. Loss of charge at residues E51, D54, and E56 altered local folding and overall stability of the F protein, with dramatic consequences for fusion activity. As a whole, these studies implicate charged residues and potential electrostatic interactions in function, pH sensing, and overall stability of HMPV F.

  8. High-Performance Water Filtration Membranes using Surface Modification and New Materials

    NASA Astrophysics Data System (ADS)

    Huang, Xinwei

    Water scarcity is one of the most critical challenges faced by mankind and it is only getting worse due to source pollution and rising population. There is critical need for the development of water filtration membranes in order to treat polluted water and turn water from non-potable sources such as waste waster and ocean water into freshwater for human consumption and agricultural irrigation. Filtration Membranes are generally classified into four categories: microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), with decreasing pore size for rejecting different sized substances. Commercial filtration membranes are able to provide decent flux and rejection for their targeted applications. However, most of them suffer from fouling issues when the microorganisms and organic matter such as proteins and polysaccharides in the water source deposit onto the membrane surface, impeding the permeation of water and lowering the flux. Therefore, it is of high demand to develop membranes that are anti-fouling. Foulants such as protein particles adhere to the membrane surface via hydrophobic interactions. In order to minimize such effects, a typical way is to increase the hydrophilicity of the membrane by surface modification or by utilizing hydrophilic membrane materials. Foulants also tend to get trapped in the open "pores" on a rough membrane surface with ridges and valleys. It is then expected that a smoother membrane surface tend to lessen such effects. Incorporating antimicrobial properties into the membrane is also an effective way to reduce fouling as this inhibits the growth of microorganisms on the membrane surfaces. New materials are also used to fabricate membranes with improved performance. Conducting polymers have recently been discovered as a new category of membrane-making materials that are hydrophilic and low-fouling. A new type of polyaniline derivative has been used to fabricate UF membranes that demonstrate chlorine

  9. Heteroepitaxially grown zeolitic imidazolate framework membranes with unprecedented propylene/propane separation performances.

    PubMed

    Kwon, Hyuk Taek; Jeong, Hae-Kwon; Lee, Albert S; An, He Seong; Lee, Jong Suk

    2015-09-30

    Propylene/propane separation is one of the most challenging separations, currently achieved by energy-intensive cryogenic distillation. Despite the great potential for energy-efficient membrane-based separations, no commercial membranes are currently available due to the limitations of current polymeric materials. Zeolitic imidazolate framework, ZIF-8, with the effective aperture size of ∼4.0 Å, has been shown to be very promising for propylene/propane separation. Despite the extensive research on ZIF-8 membranes, only a few reported ZIF-8 membranes have displayed good propylene/propane separation performances presumably due to the challenges of controlling the microstructures of polycrystalline membranes. Here we report the first well-intergrown membranes of ZIF-67 (Co-substituted ZIF-8) by heteroepitaxially growing ZIF-67 on ZIF-8 seed layers. The ZIF-67 membranes exhibited impressively high propylene/propane separation capabilities. Furthermore, when a tertiary growth of ZIF-8 layers was applied to heteroepitaxially grown ZIF-67 membranes, the membranes exhibited unprecedentedly high propylene/propane separation factors of ∼200 possibly due to enhanced grain boundary structure.

  10. A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes

    PubMed Central

    Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A.; Sadrzadeh, Mohtada

    2016-01-01

    A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from −20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at −20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes. PMID:26924449

  11. A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes

    NASA Astrophysics Data System (ADS)

    Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A.; Sadrzadeh, Mohtada

    2016-02-01

    A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from ‑20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at ‑20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes.

  12. Calcium influx affects intracellular transport and membrane repair following nanosecond pulsed electric field exposure

    NASA Astrophysics Data System (ADS)

    Thompson, Gary Lee; Roth, Caleb C.; Dalzell, Danielle R.; Kuipers, Marjorie; Ibey, Bennett L.

    2014-05-01

    The cellular response to subtle membrane damage following exposure to nanosecond pulsed electric fields (nsPEF) is not well understood. Recent work has shown that when cells are exposed to nsPEF, ion permeable nanopores (<2 nm) are created in the plasma membrane in contrast to larger diameter pores (>2 nm) created by longer micro- and millisecond duration pulses. Nanoporation of the plasma membrane by nsPEF has been shown to cause a transient increase in intracellular calcium concentration within milliseconds after exposure. Our research objective is to determine the impact of nsPEF on calcium-dependent structural and repair systems in mammalian cells. Chinese hamster ovary (CHO-K1) cells were exposed in the presence and absence of calcium ions in the outside buffer to either 1 or 20, 600-ns duration electrical pulses at 16.2 kV/cm, and pore size was determined using propidium iodide and calcium green. Membrane organization was observed with morphological changes and increases in FM1-43 fluorescence. Migration of lysosomes, implicated in membrane repair, was followed using confocal microscopy of red fluorescent protein-tagged LAMP1. Microtubule structure was imaged using mEmerald-tubulin. We found that at high 600-ns PEF dosage, calcium-induced membrane restructuring and microtubule depolymerization coincide with interruption of membrane repair via lysosomal exocytosis.

  13. Calcium influx affects intracellular transport and membrane repair following nanosecond pulsed electric field exposure.

    PubMed

    Thompson, Gary Lee; Roth, Caleb C; Dalzell, Danielle R; Kuipers, Marjorie; Ibey, Bennett L

    2014-05-01

    The cellular response to subtle membrane damage following exposure to nanosecond pulsed electric fields (nsPEF) is not well understood. Recent work has shown that when cells are exposed to nsPEF, ion permeable nanopores (<2  nm) are created in the plasma membrane in contrast to larger diameter pores (>2  nm) created by longer micro- and millisecond duration pulses. Nanoporation of the plasma membrane by nsPEF has been shown to cause a transient increase in intracellular calcium concentration within milliseconds after exposure. Our research objective is to determine the impact of nsPEF on calcium-dependent structural and repair systems in mammalian cells. Chinese hamster ovary (CHO-K1) cells were exposed in the presence and absence of calcium ions in the outside buffer to either 1 or 20, 600-ns duration electrical pulses at 16.2  kV/cm, and pore size was determined using propidium iodide and calcium green. Membrane organization was observed with morphological changes and increases in FM1-43 fluorescence. Migration of lysosomes, implicated in membrane repair, was followed using confocal microscopy of red fluorescent protein-tagged LAMP1. Microtubule structure was imaged using mEmerald-tubulin. We found that at high 600-ns PEF dosage, calcium-induced membrane restructuring and microtubule depolymerization coincide with interruption of membrane repair via lysosomal exocytosis.

  14. Evaluation of membrane performance and fouling by pyrolysis-GC/MS

    SciTech Connect

    Speth, T.F.; Fromme, W.R.; Summers, R.S.

    1995-10-01

    The loss of membrane efficiency due to fouling is one of the main impediments to the development of membrane processes for use in drinking water treatment. Membrane fouling is dependent on the water quality and the membrane properties and construction. In general, fouling is defined as the accumulation of material on the surface, or in the pores, of a membrane that decreases the water flux through the membrane. The consequences of fouling can be severe, fouling can reduce the water flux through a membrane up to 90 percent. There are five broad fouling categories: sparingly soluble inorganics, colloidal or particulate matter, dissolved organics, chemical reactants, and microorganisms. Dissolved organics and colloidal matter are considered to be the most serious of the foulants due to the difficulty in removing them with pretreatment processes. Membranes can be fouled either by cake-layer formation or adsorption. Improved nanofiltration performance will lead to an increased use of nanofiltration as a drinking water treatment method. Pyrolysis-gas chromatography/mass spectroscopy (Py-GC/MS) has the ability to elucidate natural organic matter characteristics. Pyrolysis is used to thermally cleave organic molecules into volatile fragments that are then separated by gas chromatography and identified by mass spectroscopy. The objective of this research is to relate the productivity of membrane systems that treat different water`s to natural organic characteristics as determined by Py-GC/MS. Membrane studies will be completed with a cellulose acetate membrane that has a nominal molecular-weight cutoff of 500 Daltons (Amicon YCO5), and a thin-film polyamide membrane (Fluid Systems) that has a nominal molecular-weight cutoff of 200 Daltons.

  15. Supported Ionic Liquid Membranes and Ion-Jelly® Membranes with [BMIM][DCA]: Comparison of Its Performance for CO2 Separation

    PubMed Central

    Couto, Ricardo; Neves, Luísa; Simões, Pedro; Coelhoso, Isabel

    2015-01-01

    In this work, a supported ionic liquid membrane (SILM) was prepared by impregnating a PVDF membrane with 1-butyl-3-methylimidazolium dicyanamide ([BMIM][DCA]) ionic liquid. This membrane was tested for its permeability to pure gases (CO2, N2 and O2) and ideal selectivities were calculated. The SILM performance was also compared to that of Ion-Jelly® membranes, a new type of gelled membranes developed recently. It was found that the PVDF membrane presents permeabilities for pure gases similar or lower to those presented by the Ion-Jelly® membranes, but with increased ideal selectivities. This membrane presents also the highest ideal selectivity (73) for the separation of CO2 from N2 when compared with SILMs using the same PVDF support but with different ionic liquids. PMID:25594165

  16. Supported Ionic Liquid Membranes and Ion-Jelly® Membranes with [BMIM][DCA]: Comparison of Its Performance for CO2 Separation.

    PubMed

    Couto, Ricardo; Neves, Luísa; Simões, Pedro; Coelhoso, Isabel

    2015-01-14

    In this work, a supported ionic liquid membrane (SILM) was prepared by impregnating a PVDF membrane with 1-butyl-3-methylimidazolium dicyanamide ([BMIM][DCA]) ionic liquid. This membrane was tested for its permeability to pure gases (CO2, N2 and O2) and ideal selectivities were calculated. The SILM performance was also compared to that of Ion-Jelly® membranes, a new type of gelled membranes developed recently. It was found that the PVDF membrane presents permeabilities for pure gases similar or lower to those presented by the Ion-Jelly® membranes, but with increased ideal selectivities. This membrane presents also the highest ideal selectivity (73) for the separation of CO2 from N2 when compared with SILMs using the same PVDF support but with different ionic liquids.

  17. Characterization and anti-fouling performance of nano-Al₂O₃/PVDF membrane for Songhua river raw water filtration.

    PubMed

    Yu, S L; Shi, W X; Lu, Y; Yang, J X

    2011-01-01

    Polyvinylidene fluoride (PVDF) flat ultrafiltration membranes modified by nano-sized alumina (Al₂O₃) particles were prepared by phase inversion process and their properties and anti-fouling performances were examined. The influence of three types of natural organic matters on the modified membrane fouling was also studied. Raw water was taken from two different locations, i.e., Harbin and Zhaoyuan, of Songhua River. Dissolved organic compounds in the raw water were fractionated using XAD resins into three fractions, i.e., hydrophobic fraction, transphilic fraction, and hydrophilic fraction (HPI). The three adsorbed compounds were further eluted and dissolved into distilled water respectively to prepare the feed for the fouling tests. All solutions were adjusted to a concentration of 10.6 mg C/L, which equals to the total organic carbon (TOC) of the raw water. Results show that the addition of nano-Al₂O₃ particulars did not affect the inherent traits of the PVDF membranes, however, its surface hydrophilic properties were improved significantly with the addition of nanoparticles and anti-fouling performance was enhanced as well. The HPIs in the Songhua River were the main foulant, causing more fouling to membrane than hydrophobic and transphilic matters.

  18. Item Context Factors Affecting Students' Performance on Mathematics Items

    ERIC Educational Resources Information Center

    Salgado, Felipe Almuna; Stacey, Kaye

    2014-01-01

    This paper reports how the context in which a mathematics item is embedded impacts on students' performance. The performance of Year 10 students on four PISA items was compared with performance on variants with more familiar contexts. Performance was not better when they solved items with more familiar contexts but there was some evidence that…

  19. Altered membrane lipid composition and functional parameters of circulating cells in cockles (Cerastoderma edule) affected by disseminated neoplasia.

    PubMed

    Le Grand, Fabienne; Soudant, Philippe; Marty, Yanic; Le Goïc, Nelly; Kraffe, Edouard

    2013-01-01

    Membrane lipid composition and morpho-functional parameters were investigated in circulating cells of the edible cockle (Cerastoderma edule) affected by disseminated neoplasia (neoplastic cells) and compared to those from healthy cockles (hemocytes). Membrane sterol levels, phospholipid (PL) class and subclass proportions and their respective fatty acid (FA) compositions were determined. Morpho-functional parameters were evaluated through total hemocyte count (THC), mortality rate, phagocytosis ability and reactive oxygen species (ROS) production. Both morpho-functional parameters and lipid composition were profoundly affected in neoplastic cells. These dedifferentiated cells displayed higher THC (5×), mortality rate (3×) and ROS production with addition of carbonyl cyanide m-chloro phenylhydrazone (1.7×) but lower phagocytosis ability (½×), than unaffected hemocytes. Total PL amounts were higher in neoplastic cells than in hemocytes (12.3 and 5.1 nmol×10(-6) cells, respectively). However, sterols and a particular subclass of PL (plasmalogens; 1-alkenyl-2-acyl PL) were present in similar amounts in both cell type membranes. This led to a two times lower proportion of these membrane lipid constituents in neoplastic cells when compared to hemocytes (20.5% vs. 42.1% of sterols in total membrane lipids and 21.7% vs. 44.2% of plasmalogens among total PL, respectively). Proportions of non-methylene interrupted FA- and 20:1n-11-plasmalogen molecular species were the most impacted in neoplastic cells when compared to hemocytes (⅓× and ¼×, respectively). These changes in response to this leukemia-like disease in bivalves highlight the specific imbalance of plasmalogens and sterols in neoplastic cells, in comparison to the greater stability of other membrane lipid components.

  20. The influence of zeolite (clinoptilolite) on the performance of a hybrid membrane bioreactor.

    PubMed

    Rezaei, M; Mehrnia, M R

    2014-04-01

    This work aims to investigate the effect of clinoptilolite on the performance of membrane bioreactor (MBR). The control membrane bioreactor without clinoptilolite (CMBR) and the hybrid membrane bioreactor with clinoptilolite (HMBR), in two parallel simultaneous MBRs within long and short term filtration experiments, were studied. Sludge properties, transmembrane pressure (TMP) rise as an index for membrane fouling and nutrient removal from synthetic wastewater in the CMBR and HMBR were compared. In HMBR, sludge properties improvement such as 22.5% rise in MLSS, 7% more accumulation of large particles, reduction of soluble microbial products (SMP) to half of this value in CMBR, no increase in sludge volume index (SVI) and 66% TMP reduced. The results of short term filtration showed that the trend of TMP increase in terms of flux will be slower in HMBR. Improvement of biological wastewater treatment quality and ease of membrane operation are concluded from this study.

  1. High performance zeolite LTA pervaporation membranes on ceramic hollow fibers by dipcoating-wiping seed deposition.

    PubMed

    Wang, Zhengbao; Ge, Qinqin; Shao, Jia; Yan, Yushan

    2009-05-27

    We demonstrate for the first time that by one single hydrothermal synthesis a zeolite LTA membrane with a high flux of 9.0 kg/m(2) h and high water/ethanol separation factor of 10,000 could be formed on a ceramic hollow fiber that is known for its ability to form a compact module. The flux is the highest reported in the literatures. A novel seeding method, dipcoating-wiping, is key to obtaining zeolite membranes with high separation performance because it reproducibly produces a uniform and trace seed layer on the support. This new seeding method is expected to have serious implications for making defect-free zeolite films and membranes for many applications. The membranes reported here have the potential to solve the key problems that have prevented zeolite membranes from widespread use for biofuel production.

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

    PubMed

    Ge, Qinqin; Wang, Zhengbao; Yan, Yushan

    2009-12-02

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

  3. High Performance Fuel Cell and Electrolyzer Membrane Electrode Assemblies (MEAs) for Space Energy Storage Systems

    NASA Technical Reports Server (NTRS)

    Valdez, Thomas I.; Billings, Keith J.; Kisor, Adam; Bennett, William R.; Jakupca, Ian J.; Burke, Kenneth; Hoberecht, Mark A.

    2012-01-01

    Regenerative fuel cells provide a pathway to energy storage system development that are game changers for NASA missions. The fuel cell/ electrolysis MEA performance requirements 0.92 V/ 1.44 V at 200 mA/cm2 can be met. Fuel Cell MEAs have been incorporated into advanced NFT stacks. Electrolyzer stack development in progress. Fuel Cell MEA performance is a strong function of membrane selection, membrane selection will be driven by durability requirements. Electrolyzer MEA performance is catalysts driven, catalyst selection will be driven by durability requirements. Round Trip Efficiency, based on a cell performance, is approximately 65%.

  4. Impact of synthetic or real urban wastewater on membrane bioreactor (MBR) performances and membrane fouling under stable conditions.

    PubMed

    Villain, Maud; Bourven, Isabelle; Guibaud, Gilles; Marrot, Benoît

    2014-03-01

    Influence of substrate type (synthetic (SWW) or real wastewater (RWW)) on lab scale MBR performances (e.g. COD and N-NH4(+) removal rates and bioactivities) was assessed. Membrane fouling was related to MBR biological medium characteristics. With RWW, autotrophic biomass was better acclimated with complete ammonium removal. MBR biological medium was characterized by main soluble microbial products (SMP) (proteins, polysaccharides and humic-like substances) quantification and molecular weights (MW) distribution determination. The biological medium of SWW acclimation contained 60mgL(-1) more of SMP, mainly composed of proteins and polysaccharides. A protein fraction having high MW (>600kDa) could be responsible for higher removable fouling fraction in that case. SMP of RWW experiment were mainly composed of small proteic and humic-like fractions, poorly retained by the membrane and resulting in a weak augmentation of irremovable and irreversible fouling fractions compared to SWW acclimation. Therefore RWW utilization is preferable to approach real operating MBR.

  5. Acute intrastriatal administration of quinolinic acid affects the expression of the coat protein AP-2 and its interaction with membranes.

    PubMed

    Borgonovo, Janina; Seltzer, Alicia; Sosa, Miguel Angel

    2009-10-01

    Clathrin-coated vesicle endocytosis is thought to be crucial for the maintenance of synaptic transmission and for the cell plasticity at the nervous system. In this study, we demonstrated that acute intrastriatal administration of quinolinic acid (QUIN), an agonist of the N-methyl-D: -aspartate receptor, induces a decrease of the coat protein AP-2 expression and affects their interaction with membranes. By western blot analysis we observed that at 24 h after QUIN intrastriatal injection, alpha1 subunit of AP-2 and alpha2, at lesser extent, were reduced in the striatal membranes. The decrease of both subunits expression was extended to 48 h after treatment, although the soluble proteins were mostly affected. Other areas of the brain were not affected by the treatment, except the cerebellum, where a significant increase of soluble AP-2 (both subunits) was observed at 48 h after injection. Another coat protein, as the phosphoprotein AP-180, was not affected by the injection of QUIN. We also confirmed that QUIN injection causes increasing loss of striatal neurons after the administration of the toxin. We concluded that QUIN may affect the endocytotic machinery of the striatum, by inducing changes in the AP-2 behaviour. Consequently, the internalization of NMDAR and/or AMPAR may be affected, by QUIN, contributing to the excitotoxic effect of the drug.

  6. Membrane installation for enhanced up-flow anaerobic sludge blanket (UASB) performance.

    PubMed

    Liu, Yin; Zhang, Kaisong; Bakke, Rune; Li, Chunming; Liu, Haining

    2013-09-01

    It is postulated that up-flow anaerobic sludge blanket (UASB) reactor efficiency can be enhanced by a membrane immersed in the reactor to operate it as an anaerobic membrane bioreactor (AnMBR) for low-strength wastewater treatment. This postulate was tested by comparing the performance with and without a hollow fiber microfiltration membrane module immersed in UASB reactors operated at two specific organic loading rates (SOLR). Results showed that membrane filtration enhanced process performance and stability, with over 90% total organic carbon (TOC) removal consistently achieved. More than 91% of the TOC removal was achieved by suspended biomass, while less than 6% was removed by membrane filtration and digestion in the membrane attached biofilm during stable AnMBRs operation. Although the membrane and its biofilm played an important role in initial stage of the high SOLR test, linear increased TOC removal by bulk sludge mainly accounted for the enhanced process performance, implying that membrane led to enhanced biological activity of the suspended sludge. The high retention of active fine sludge particles in suspension was the main reason for this significant improvement of performance and biological activity, which led to decreased SOLR with time to a theoretical optimal level around 2  g COD/g MLVSS·d and the establishment of a microbial community dominated by Methanothrix-like microbes. It was concluded that UASB process performance can be enhanced by transforming such to AnMBR operation when the loading rate is too high for sufficient sludge retention, and/or when the effluent water quality demands are especially stringent.

  7. Preparation and Preliminary Dialysis Performance Research of Polyvinylidene Fluoride Hollow Fiber Membranes

    PubMed Central

    Zhang, Qinglei; Lu, Xiaolong; Liu, Juanjuan; Zhao, Lihua

    2015-01-01

    In this study, the separation properties of Polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were improved by optimizing membrane morphology and structure. The results showed that the PVDF membrane had better mechanical and separation properties than Fresenius Polysulfone High-Flux (F60S) membrane. The PVDF membrane tensile stress at break, tensile elongation and bursting pressure were 11.3 MPa, 395% and 0.625 MPa, respectively. Ultrafiltration (UF) flux of pure water reached 108.2 L∙h−1∙m−2 and rejection of Albumin from bovine serum was 82.3%. The PVDF dialyzers were prepared by centrifugal casting. The influences of membrane area and simulate fluid flow rate on dialysis performance were investigated. The results showed that the clearance rate of urea and Lysozyme (LZM) were improved with increasing membrane area and fluid flow rate while the rejection of albumin from bovine serum (BSA) had little influence. The high-flux PVDF dialyzer UF coefficient reached 62.6 mL/h/mmHg. The PVDF dialyzer with membrane area 0.69 m2 has the highest clearance rate to LZM and urea. The clearance rate of LZM was 66.8% and urea was 87.7%. PMID:25807890

  8. Preparation and preliminary dialysis performance research of polyvinylidene fluoride hollow fiber membranes.

    PubMed

    Zhang, Qinglei; Lu, Xiaolong; Liu, Juanjuan; Zhao, Lihua

    2015-03-19

    In this study, the separation properties of Polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were improved by optimizing membrane morphology and structure. The results showed that the PVDF membrane had better mechanical and separation properties than Fresenius Polysulfone High-Flux (F60S) membrane. The PVDF membrane tensile stress at break, tensile elongation and bursting pressure were 11.3 MPa, 395% and 0.625 MPa, respectively. Ultrafiltration (UF) flux of pure water reached 108.2 L∙h-1∙m-2 and rejection of Albumin from bovine serum was 82.3%. The PVDF dialyzers were prepared by centrifugal casting. The influences of membrane area and simulate fluid flow rate on dialysis performance were investigated. The results showed that the clearance rate of urea and Lysozyme (LZM) were improved with increasing membrane area and fluid flow rate while the rejection of albumin from bovine serum (BSA) had little influence. The high-flux PVDF dialyzer UF coefficient reached 62.6 mL/h/mmHg. The PVDF dialyzer with membrane area 0.69 m2 has the highest clearance rate to LZM and urea. The clearance rate of LZM was 66.8% and urea was 87.7%.

  9. Investigation on surface molecular conformations and pervaporation performance of the poly(vinyl alcohol) (PVA) membrane.

    PubMed

    Zhang, Wei; Zhang, Zhennan; Wang, Xinping

    2009-05-01

    A simple method of changing pre-treatment temperature in the course of film formation was used to tune the surface structures of PVA membranes. Surface structure and property of the resulting membranes were characterized by X-ray photoelectron spectroscopy (XPS), sum frequency generation (SFG) vibrational spectroscopy, and contact angle measurements. The results show that PVA have different molecular conformations at the membrane surface while those membranes were prepared at different pre-treatment temperature. At higher pre-treatment temperatures, polar acetoxyl residues and hydroxyl groups of the PVA chains oriented in a more orderly fashion, as induced by the faster evaporation of water. When the membranes were in air, CH(3) groups adjacent to the acetoxyl groups covered the surface in order to minimize the surface free energy, while backbones of the PVA were rarely observed. These surfaces exhibited a hydrophilic nature upon contact with water due to rapid surface reconstruction. Conversely, at lower pre-treatment temperatures, the backbone CH(2) groups dominated the surface, forming a less hydrophilic surface. When the PVA membranes were employed to separate ethanol/water mixtures, it was found that the PVA membranes with more hydrophilic surface exhibited higher water selectivity. Our investigation indicates that molecular conformations on the membrane surface have considerable influence on pervaporation performance.

  10. Improving the Performance and Antifouling Properties of Thin-Film Composite Membranes for Water Separation Technologies

    NASA Astrophysics Data System (ADS)

    Tiraferri, Alberto

    Membrane-based water separation processes utilize semi-permeable membranes to retain dissolved solids and contaminants. Deployment of these technologies for desalination and wastewater reuse has the potential to sustainably increase the supply of potable, agricultural, and industrial water. Despite considerable development of semi-permeable membranes in the last decades, several design obstacles hampering their progress have yet to be overcome. Specifically, major membrane improvements are currently sought with respect to their performance and productivity, as well as their resistance to fouling. This dissertation research aims at the advancement of semi-permeable membranes by rational optimization of their design to: (i) understand and improve their transport properties and (ii) reduce fouling by organic molecules and delay biofouling by microorganisms. In particular, thin-film composite polyamide membranes for both reverse osmosis and forward osmosis processes are the main target of the investigation. The structural and physicochemical properties of thin-film composite membranes are both characterized and tailored through implementation of original techniques and novel functionalization protocols. The membrane structure and morphology are rationally modified to enhance the mass transport within the support layer. The influence of fabrication conditions on support layer formation and on its final structure is elucidated. The intricate interrelationship among the performance of the different layers of the composite membrane is highlighted and a new protocol is developed to characterize the transport properties of membranes deployed in forward osmosis processes. Novel approaches to impart targeted properties to the active surface of thin-film composite membranes are also proposed. The functionalization is achieved by exploiting the inherent moieties of the polyamide layer to irreversibly bind nanomaterials with desired properties. An experimental method to determine

  11. Performances and fouling control of a flat sheet membrane in a MBR pilot-plant.

    PubMed

    Grélot, A; Grelier, P; Tazi-Pain, A; Lesjean, B; Brüss, U; Grasmick, A

    2010-01-01

    This paper deals with the performance and the optimisation of the hydraulic operating conditions of the A3 Water Solutions flat sheet membrane technology in a MBR pilot-plant to achieve a satisfying fouling control and also a reduction in the required aeration. Two vertically stacked modules were tested at pilot-scale at Anjou Recherche under typical biological operating conditions (mixed liquor suspended solids concentration (MLSS) =10 g/l; sludge retention time (SRT) =28 days; food to microorganism ratio (F/M)=0.12 kg COD/kg MLSS/d). The use of a double-deck and of specific backwashes for this membrane technology enabled to achieve satisfying membrane performances for a net flux of 25 L h(-1) m(-2), 20 degrees C at a low specific aeration demand per membrane surface (SADm = 0.2 Nm(3) h(-1) m(-2)) which corresponds to a specific aeration demand per permeate volume unit (SADp) of 8 Nm(3) air/m(3) permeate, which is lower than reported for many commercial membrane systems. The mixed liquor characteristics (foaming, MLSS concentration) appeared to influence the fouling behaviour of the membranes but no correlation was found with the fouling rate. However, with the new operating conditions, the system is robust and can cope with fouling resulting from biological stress and daily peak flows for MLSS concentrations in the membrane tank up to 18 g/l.

  12. Electrochemical performance and transport properties of a Nafion membrane in a hydrogen-bromine cell environment

    NASA Technical Reports Server (NTRS)

    Baldwin, Richard S.

    1987-01-01

    The overall energy conversion efficiency of a hydrogen-bromine energy storage system is highly dependent upon the characteristics and performance of the ion-exchange membrane utilized as a half-cell separator. The electrochemical performance and transport properties of a duPont Nafion membrane in an aqueous HBr-Br2 environment were investigated. Membrane conductivity data are presented as a function of HBr concentration and temperature for the determination of ohmic voltage losses across the membrane in an operational cell. Diffusion-controlled bromine permeation rates and permeabilities are presented as functions of solution composition and temperature. Relationships between the degree of membrane hydration and the membrane transport characteristics are discussed. The solution chemistry of an operational hydrogen-bromine cell undergoing charge from 45% HBr to 5% HBr is discussed, and, based upon the experimentally observed bromine permeation behavior, predicted cell coulombic losses due to bromine diffusion through the membrane are presented as a function of the cell state-of-charge.

  13. Harvesting microalgal biomass using a magnetically induced membrane vibration (MMV) system: filtration performance and energy consumption.

    PubMed

    Bilad, M R; Discart, V; Vandamme, D; Foubert, I; Muylaert, K; Vankelecom, Ivo F J

    2013-06-01

    This study was performed to investigate the effectiveness of submerged microfiltration to harvest both a marine diatom Phaeodactylum tricornutum and a Chlorella vulgaris in a recently developed magnetically induced membrane vibrating (MMV) system. We assess the filtration performance by conducting the improved flux step method (IFM), fed-batch concentration filtrations and membrane fouling autopsy using two lab-made membranes with different porosity. The full-scale energy consumption was also estimated. Overall results suggest that the MMV offers a good fouling control and the process was proven to be economically attractive. By combining the membrane filtration (15× concentration) with centrifugation to reach a final concentration of 25% w/v, the energy consumption to harvest P. tricornutum and C. vulgaris was, respectively, as low as 0.84 and 0.77kWh/m(3), corresponding to 1.46 and 1.39 kWh/kg of the harvested biomass.

  14. Amide functionalized MWNT/SPEEK composite membrane for better electrochemical performance

    NASA Astrophysics Data System (ADS)

    Gahlot, Swati; Sharma, Prem P.; Kulshrestha, Vaibhav

    2016-05-01

    Nanocomposite membranes based on multiwalled carbon nanotube /SPEEK (sulfonated poly ether ether ketone) have been synthesized via simple solution casting. Prior to use CNT have been purified and grafted with carboxylic acid groups onto its walls by means of sulfuric and nitric acid. Afterwards, amidation of carboxylated CNTs (c-CNT) has been done. Amidated CNT (a-CNT) is then incorporated in SPEEK polymer matrix to synthesize nanocomposite membranes. Physicochemical, structural, thermal and mechanical characterizations are done through the respective techniques. Electric and ionic conductivities have also been evaluated. Composites membranes show the enhanced electrochemical performance with higher electric conductivity.

  15. Enhancement of the fuel cell performance of a high temperature proton exchange membrane fuel cell running with titanium composite polybenzimidazole-based membranes

    NASA Astrophysics Data System (ADS)

    Lobato, Justo; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Pinar, F. Javier

    2011-10-01

    The fuel cell performance of a composite PBI-based membrane with TiO2 has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The PBI composite membrane incorporating TiO2 showed the best performance and reached 1000 mW cm-2 at 175 °C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 mΩ cm2 h-1 and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H3PO4/PBI r.u. whereas the PBI standard membrane only retained 1 mol H3PO4/PBI r.u. Taking into account the results obtained in this study, the TiO2-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs.

  16. Performance of composite Nafion/PVA membranes for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Mollá, Sergio; Compañ, Vicente

    2011-03-01

    This work has been focused on the characterization of the methanol permeability and fuel cell performance of composite Nafion/PVA membranes in function of their thickness, which ranged from 19 to 97 μm. The composite membranes were made up of Nafion® polymer deposited between polyvinyl alcohol (PVA) nanofibers. The resistance to methanol permeation of the Nafion/PVA membranes shows a linear variation with the thickness. The separation between apparent and true permeability permits to give an estimated value of 4.0 × 10-7 cm2 s-1 for the intrinsic or true permeability of the bulk phase at the composite membranes. The incorporation of PVA nanofibers causes a remarkable reduction of one order of magnitude in the methanol permeability as compared with pristine Nafion® membranes. The DMFC performances of membrane-electrode assemblies prepared from Nafion/PVA and pristine Nafion® membranes were tested at 45, 70 and 95 °C under various methanol concentrations, i.e., 1, 2 and 3 M. The nanocomposite membranes with thicknesses of 19 μm and 47 μm reached power densities of 211 mW cm-2 and 184 mW cm-2 at 95 °C and 2 M methanol concentration. These results are comparable to those found for Nafion® membranes with similar thickness at the same conditions, which were 210 mW cm-2 and 204 mW cm-2 respectively. Due to the lower amount of Nafion® polymer present within the composite membranes, it is suggested a high degree of utilization of Nafion® as proton conductive material within the Nafion/PVA membranes, and therefore, significant savings in the consumed amount of Nafion® are potentially able to be achieved. In addition, the reinforcement effect caused by the PVA nanofibers offers the possibility of preparing membranes with very low thickness and good mechanical properties, while on the other hand, pristine Nafion® membranes are unpractical below a thickness of 50 μm.

  17. Performance and Results of the LBNE 35 Ton Membrane Cryostat Prototype

    NASA Astrophysics Data System (ADS)

    Montanari, David; Adamowski, Mark; Hahn, Alan; Norris, Barry; Reichenbacher, Juergen; Rucinski, Russell; Stewart, Jim; Tope, Terry

    We report on the performance and commissioning of the first membrane cryostat to be used for scientific application. The Long Baseline Neutrino Experiment (LBNE) has designed and fabricated a membrane cryostat prototype in collaboration with Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI). LBNE has designed and fabricated the supporting cryogenic system infrastructure and successfully commissioned and operated the first membrane cryostat. Original goals of the prototype are: to demonstrate the membrane cryostat technology in terms of thermal performance, feasibility for liquid argon and leak tightness; to demonstrate that we can remove all the impurities from the vessel and achieve the purity requirements in a membrane cryostat without evacuation; to demonstrate that we can achieve and maintain the purity requirements of the liquid argon using mol sieve and copper filters. The purity requirements of a large liquid argon detector such as LBNE are contaminants below 200 parts per trillion (ppt) oxygen equivalent. LBNE is planning the design and construction of a large liquid argon detector. This presentation will present requirements, design and construction of the LBNE 35 ton membrane cryostat prototype, and detail the commissioning and performance. The experience and results of this prototype are extremely important for the development of the LBNE detector.

  18. Performance and results of the LBNE 35 ton membrane cryostat prototype

    DOE PAGES

    Montanari, David; Adamowski, Mark; Hahn, Alan; ...

    2015-07-15

    We report on the performance and commissioning of the first membrane cryostat to be used for scientific application. The Long Baseline Neutrino Experiment (LBNE) has designed and fabricated a membrane cryostat prototype in collaboration with Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI). LBNE has designed and fabricated the supporting cryogenic system infrastructure and successfully commissioned and operated the first membrane cryostat. Original goals of the prototype are: to demonstrate the membrane cryostat technology in terms of thermal performance, feasibility for liquid argon and leak tightness; to demonstrate that we can remove all the impurities from the vessel and achieve the puritymore » requirements in a membrane cryostat without evacuation; to demonstrate that we can achieve and maintain the purity requirements of the liquid argon using mol sieve and copper filters. The purity requirements of a large liquid argon detector such as LBNE are contaminants below 200 parts per trillion (ppt) oxygen equivalent. LBNE is planning the design and construction of a large liquid argon detector. This presentation will present requirements, design and construction of the LBNE 35 ton membrane cryostat prototype, and detail the commissioning and performance. The experience and results of this prototype are extremely important for the development of the LBNE detector.« less

  19. Performance and results of the LBNE 35 ton membrane cryostat prototype

    SciTech Connect

    Montanari, David; Adamowski, Mark; Hahn, Alan; Norris, Barry; Reichenbacher, Juergen; Rucinski, Russell; Stewart, Jim; Tope, Terry

    2015-07-15

    We report on the performance and commissioning of the first membrane cryostat to be used for scientific application. The Long Baseline Neutrino Experiment (LBNE) has designed and fabricated a membrane cryostat prototype in collaboration with Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI). LBNE has designed and fabricated the supporting cryogenic system infrastructure and successfully commissioned and operated the first membrane cryostat. Original goals of the prototype are: to demonstrate the membrane cryostat technology in terms of thermal performance, feasibility for liquid argon and leak tightness; to demonstrate that we can remove all the impurities from the vessel and achieve the purity requirements in a membrane cryostat without evacuation; to demonstrate that we can achieve and maintain the purity requirements of the liquid argon using mol sieve and copper filters. The purity requirements of a large liquid argon detector such as LBNE are contaminants below 200 parts per trillion (ppt) oxygen equivalent. LBNE is planning the design and construction of a large liquid argon detector. This presentation will present requirements, design and construction of the LBNE 35 ton membrane cryostat prototype, and detail the commissioning and performance. The experience and results of this prototype are extremely important for the development of the LBNE detector.

  20. How Does Test Exemption Affect Schools' and Students' Academic Performance?

    ERIC Educational Resources Information Center

    Jennings, Jennifer L.; Beveridge, Andrew A.

    2009-01-01

    Analyzing data from a large urban district in Texas, this study examines how high-stakes test exemptions alter officially reported scores and asks whether test exemption has implications for the academic achievement of special education students. Test exemption inflated overall passing rates but especially affected the passing rates of African…

  1. Selected Factors Affecting the Performance Assessment of Elementary Teachers.

    ERIC Educational Resources Information Center

    Thomson, Scott

    1990-01-01

    This study determined whether nontraditional assessment factors (principal's gender, choice of subject matter for demonstrating competence, or years of teacher experience) would affect elementary teachers' scores when completing the Leon County (Florida) Teacher Assessment Process. Principal's gender and subject selected were significant…

  2. An Analysis of Team Composition as It Affects Simulation Performance.

    ERIC Educational Resources Information Center

    Krishnakumar, Parameswar; Chisholm, Thomas Alexander

    This study investigated the extent to which sex composition and average team academic achievement of student simulation teams affect team effectiveness. Seventy-four students in two sections of a marketing principles class were divided into 20 teams to test their decision-making skills. For 10 weeks, each team operated a simulated supermarket…

  3. Certain Organizational Characteristics Affect ACO Preventive Care Quality Performance.

    PubMed

    Ticse, Caroline

    2016-06-01

    Key findings. (1) ACOs at provider workforce extremes--few primary care providers or many specialists--performed worse on measures of preventive care quality relative to those with more PCPs and fewer specialists. (2) Upfront investment in ACO formation is associated with higher performance in preventive care quality. (3) ACOs with a higher proportion of minority beneficiaries performed worse on disease prevention measures than did ACOs with a lower proportion of minority beneficiaries. (4) ACOs facing barriers to quality performance may benefit from organizational characteristics such as electronic health record capabilities and hospital inclusion in the ACO.

  4. Conductive area ratio of multiblock copolymer electrolyte membranes evaluated by e-AFM and its impact on fuel cell performance

    NASA Astrophysics Data System (ADS)

    Takimoto, Naohiko; Takamuku, Shogo; Abe, Mitsutaka; Ohira, Akihiro; Lee, Hae-Seung; McGrath, James E.

    The correlation between membrane surface morphology and fuel cell performance was investigated using a series of hydrophilic-hydrophobic multiblock copolymers based on poly(arylene ether sulfone) with different block lengths. The proton conductive regions on the membrane surface were successfully observed by using electrochemical atomic force microscopy (e-AFM). The results revealed a strong dependence of the hydrophilic/hydrophobic microphase-separated structure on the block length. The conductive area ratio (CAR) estimated from the proton conduction image decreased as the block length increased, and it was found to be closely connected with cell resistance that determines fuel cell performance. The well-defined phase-separated structure of multiblock copolymers can improve proton conductivity without any undesirable increments in water uptake or swelling, but in some instances, it affects the interfacial connection with the catalyst layer, resulting in lower fuel cell performance. The results of this study suggest the necessity for further improvement of the membrane morphology by optimizing both the casting conditions and the molecular design of the block sequences.

  5. Osmotic membrane bioreactor for wastewater treatment and the effect of salt accumulation on system performance and microbial community dynamics.

    PubMed

    Qiu, Guanglei; Ting, Yen-Peng

    2013-12-01

    An osmotic membrane bioreactor was developed for wastewater treatment. The effects of salt accumulation on system performance and microbial community dynamics were investigated. Evident deterioration of biological activity, especially nitrification, was observed, which resulted in significant accumulation of organic matter and NH4(+)-N within the bioreactor. Arising from the elevation of salinity, almost all the dominant species was taken over by high salt-tolerant species. Significant succession among different species of Nitromonas was observed for ammonia-oxidizing bacteria. For nitrite-oxidizing bacteria, Nitrospira was not evidently affected, whereas Nitrobacter was eliminated from the system. Salt accumulation also caused significant shifts in denitrifying bacterial community from α- to γ-Proteobacteria members. Overall, the microbial community adapted to the elevated salinity conditions and brought about a rapid recovery of the biological activity. Membrane fouling occurred but was insignificant. Biofouling and inorganic scaling coexisted, with magnesium/calcium phosphate/carbonate compounds identified as the inorganic foulants.

  6. Learners' Metalinguistic and Affective Performance in Blogging to Write

    ERIC Educational Resources Information Center

    Chen, Ping-Ju

    2016-01-01

    The documentation of the benefits of blog use in foreign language education has proliferated since 2006. In the field of blogging to write, most studies focus on learners' linguistic performance and perceptions. To provide an analysis of learners' writing performance by using blogs, in addition to the often-researched areas, this study examines…

  7. Young Children's Knowledge About Effects of Affect on Performance.

    ERIC Educational Resources Information Center

    Pierce, Jean W.

    1985-01-01

    Addresses the issue of whether preschoolers are aware of the connection between their emotions, their performance on a task of eye-hand coordination, and their evaluation of the task and their performance. Results indicate a developmental trend that children's predictions conform more to mood congruity theory as they grow older. (Author/DST)

  8. Highly conductive anion exchange membrane for high power density fuel-cell performance.

    PubMed

    Ren, Xiaoming; Price, Samuel C; Jackson, Aaron C; Pomerantz, Natalie; Beyer, Frederick L

    2014-08-27

    Anion exchange membrane fuel cells (AEMFCs) are regarded as a new generation of fuel cell technology that has the potential to overcome many obstacles of the mainstream proton exchange membrane fuel cells (PEMFCs) in cost, catalyst stability, efficiency, and system size. However, the low ionic conductivity and poor thermal stability of current anion exchange membranes (AEMs) have been the key factors limiting the performance of AEMFCs. In this study, an AEM made of styrenic diblock copolymer with a quaternary ammonium-functionalized hydrophilic block and a cross-linkable hydrophobic block and possessing bicontinuous phases of a hydrophobic network and hydrophilic conduction paths was found to have high ionic conductivity at 98 mS cm(-1) and controlled membrane swelling with water uptake at 117 wt % at 22 °C. Membrane characterizations and fuel cell tests of the new AEM were carried out together with a commercial AEM, Tokuyama A201, for comparison. The high ionic conductivity and water permeability of the new membrane reported in this study is attributed to the reduced torturosity of the ionic conduction paths, while the hydrophobic network maintains the membrane mechanical integrity, preventing excessive water uptake.

  9. Enhancing the performance of nanofiltration membranes by modifying the active layer with aramide dendrimers.

    PubMed

    de Jubera, Ana M Saenz; Gao, Yuan; Moore, Jeffrey S; Cahill, David G; Mariñas, Benito J

    2012-09-04

    The fully aromatic polyamide active layer of a commercial nanofiltration membrane was modified with three generations (G1, G2, and G3) of aramide dendrimers, all with oligoethylene glycol chains on their peripheries. Permeation experiments revealed that the rejection of Rhodamine WT, used as a surrogate for organic contaminants, improved 1-2 orders of magnitude for membranes modified with G2 and G3 dendrimers at loadings of 0.7-3.5 μg/cm(2) (dendrimer layer thicknesses of ~1-6 nm) compared to the performance of unmodified membranes. In contrast, the corresponding water permeability of dendrimer-modified membranes decreased by only ~30%. Although an enhancement in the rejection of H(3)AsO(3), NaCl, and BaCl(2) was also observed for dendritic membranes, the effect was less pronounced than that for rhodamine WT. Characterization of membranes modified with 3.5 μg/cm(2) dendrimers G2 and G3 by Rutherford backscattering spectrometry with the aid of heavy ion probes (Ag(+) and Ba(2+)) revealed that accessibility of the larger Ba(2+) probe to carboxylate groups on the active layer decreased for the membranes modified with dendrimers.

  10. Even a Chronic Mild Hyperglycemia Affects Membrane Fluidity and Lipoperoxidation in Placental Mitochondria in Wistar Rats

    PubMed Central

    Figueroa-García, María del Consuelo; Espinosa-García, María Teresa; Martinez-Montes, Federico; Palomar-Morales, Martín; Mejía-Zepeda, Ricardo

    2015-01-01

    It is known the deleterious effects of diabetes on embryos, but the effects of diabetes on placenta and its mitochondria are still not well known. In this work we generated a mild hyperglycemia model in female wistar rats by intraperitoneal injection of streptozotocin in 48 hours-old rats. The sexual maturity onset of the female rats was delayed around 6–7 weeks and at 16 weeks-old they were mated, and sacrificed at day 19th of pregnancy. In placental total tissue and isolated mitochondria, the fatty acids composition was analyzed by gas chromatography, and lipoperoxidation was measured by thiobarbituric acid reactive substances. Membrane fluidity in mitochondria was measured with the excimer forming probe dipyrenylpropane and mitochondrial function was measured with a Clark-type electrode. The results show that even a chronic mild hyperglycemia increases lipoperoxidation and decreases mitochondrial function in placenta. Simultaneously, placental fatty acids metabolism in total tissue is modified but in a different way than in placental mitochondria. Whereas the chronic mild hyperglycemia induced a decrease in unsaturated to saturated fatty acids ratio (U/S) in placental total tissue, the ratio increased in placental mitochondria. The measurements of membrane fluidity showed that fluidity of placenta mitochondrial membranes increased with hyperglycemia, showing consistency with the fatty acids composition through the U/S index. The thermotropic characteristics of mitochondrial membranes were changed, showing lower transition temperature and activation energies. All of these data together demonstrate that even a chronic mild hyperglycemia during pregnancy of early reproductive Wistar rats, generates an increment of lipoperoxidation, an increase of placental mitochondrial membrane fluidity apparently derived from changes in fatty acids composition and consequently, mitochondrial malfunction. PMID:26630275

  11. Even a Chronic Mild Hyperglycemia Affects Membrane Fluidity and Lipoperoxidation in Placental Mitochondria in Wistar Rats.

    PubMed

    Figueroa-García, María del Consuelo; Espinosa-García, María Teresa; Martinez-Montes, Federico; Palomar-Morales, Martín; Mejía-Zepeda, Ricardo

    2015-01-01

    It is known the deleterious effects of diabetes on embryos, but the effects of diabetes on placenta and its mitochondria are still not well known. In this work we generated a mild hyperglycemia model in female wistar rats by intraperitoneal injection of streptozotocin in 48 hours-old rats. The sexual maturity onset of the female rats was delayed around 6-7 weeks and at 16 weeks-old they were mated, and sacrificed at day 19th of pregnancy. In placental total tissue and isolated mitochondria, the fatty acids composition was analyzed by gas chromatography, and lipoperoxidation was measured by thiobarbituric acid reactive substances. Membrane fluidity in mitochondria was measured with the excimer forming probe dipyrenylpropane and mitochondrial function was measured with a Clark-type electrode. The results show that even a chronic mild hyperglycemia increases lipoperoxidation and decreases mitochondrial function in placenta. Simultaneously, placental fatty acids metabolism in total tissue is modified but in a different way than in placental mitochondria. Whereas the chronic mild hyperglycemia induced a decrease in unsaturated to saturated fatty acids ratio (U/S) in placental total tissue, the ratio increased in placental mitochondria. The measurements of membrane fluidity showed that fluidity of placenta mitochondrial membranes increased with hyperglycemia, showing consistency with the fatty acids composition through the U/S index. The thermotropic characteristics of mitochondrial membranes were changed, showing lower transition temperature and activation energies. All of these data together demonstrate that even a chronic mild hyperglycemia during pregnancy of early reproductive Wistar rats, generates an increment of lipoperoxidation, an increase of placental mitochondrial membrane fluidity apparently derived from changes in fatty acids composition and consequently, mitochondrial malfunction.

  12. Factors affecting intrauterine contraceptive device performance. I. Endometrial cavity length.

    PubMed

    Hasson, H M; Berger, G S; Edelman, D A

    1976-12-15

    The relationship of endometrial cavity length to intrauterine contraceptive device (IUD) performance was evaluated in 319 patients wearing three types of devices. The rate of events, defined as pregnancy, expulsion, or medical removal, increased significantly when the length of the IUD was equal to, exceeded, or was shorter by two or more centimeters than the length of the endometrial cavity. Total uterine length was found to be a less accurate prognostic indicator of IUD performance than endometrial cavity length alone.

  13. Performance of EVA-Based Membranes for SCL in Hard Rock

    NASA Astrophysics Data System (ADS)

    Holter, Karl Gunnar

    2016-04-01

    reduction of the tensile bond strength could be demonstrated after 35 freeze-thaw cycles with -3 °C minimum temperature at the membrane location in the lining. Further work is required to verify the performance of the SCL system under exposure to high hydrostatic pressures and the effects of long term mechanical exposure.

  14. Glutaraldehyde cross-linking of amniotic membranes affects their nanofibrous structures and limbal epithelial cell culture characteristics.

    PubMed

    Lai, Jui-Yang; Ma, David Hui-Kang

    2013-01-01

    Given that the cells can sense nanometer dimensions, the chemical cross-linking-mediated alteration in fibrillar structure of collagenous tissue scaffolds is critical to determining their cell culture performances. This article explores, for the first time, the effect of nanofibrous structure of glutaraldehyde (GTA) cross-linked amniotic membrane (AM) on limbal epithelial cell (LEC) cultivation. Results of ninhydrin assays demonstrated that the amount of new cross-links formed between the collagen chains is significantly increased with increasing the cross-linking time from 1 to 24 hours. By transmission electron microscopy, the AM treated with GTA for a longer duration exhibited a greater extent of molecular aggregation, thereby leading to a considerable increase in nanofiber diameter and resistance against collagenase degradation. In vitro biocompatibility studies showed that the samples cross-linked with GTA for 24 hours are not well-tolerated by the human corneal epithelial cell cultures. When the treatment duration is less than 6 hours, the biological tissues cross-linked with GTA for a longer time may cause slight reductions in 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt, and anti-inflammatory activities. Nevertheless, significant collagen molecular aggregation also enhances the stemness gene expression, indicating a high ability of these AM matrices to preserve the progenitors of LECs in vitro. It is concluded that GTA cross-linking of collagenous tissue materials may affect their nanofibrous structures and corneal epithelial stem cell culture characteristics. The AM treated with GTA for 6 hours holds promise for use as a niche for the expansion and transplantation of limbal epithelial progenitor cells.

  15. In vivo wound healing and antibacterial performances of electrospun nanofibre membranes.

    PubMed

    Liu, Xin; Lin, Tong; Fang, Jian; Yao, Gang; Zhao, Hongqiong; Dodson, Michael; Wang, Xungai

    2010-08-01

    In this work, nanofibre membranes have been produced from polyvinyl alcohol (PVA), polycaprolactone (PCL), polyacrylonitrile (PAN), poly (vinylidene fluoride-co-hexafluoropropene) (PVdF-HFP), and polymer blend of PAN and polyurethane (PEU) using an electrospinning technique, and wound healing performance of the as-spun nanofibre membranes was examined in vivo using female Sprague-Dawley rats. To understand the nutrition effect, a wool protein was coated on PVA and PCL nanofibres and incorporated into PVA nanofibres via coelectrospinning of a PVA solution containing the wool protein. Silver nanoparticles were also applied to PVA nanofibres to improve antibacterial activity. It was found that the wound healing performance is mainly influenced by the porosity, air permeability, and surface wettability of the nanofibre membranes. A nanofibre membrane with good hydrophilicity and high porosity considerably facilitates the healing of wound especially at the early healing stage. However, the fiber diameter and antibacterial activity have little effect on the wound healing efficiency. As pores in nanofibre membranes are typically smaller than that of conventional cotton gauze, the nanofibre membrane should be able to decontaminate and prevent exogenous infections via sieve effect. This work provides basic understanding of material structure-property relationship for further design of efficient nanofibre-based wound dressing materials.

  16. Morphological architecture of dual-layer hollow fiber for membrane distillation with higher desalination performance.

    PubMed

    Wang, Peng; Teoh, May May; Chung, Tai-Shung

    2011-11-01

    A new strategy to enhance the desalination performance of polyvinylidene fluoride (PVDF) hollow fiber membrane for membrane distillation (MD) via architecture of morphological characteristics is explored in this study. It is proposed that a dual-layer hollow fiber consisting of a fully finger-like macrovoid inner-layer and a sponge-like outer-layer may effectively enhance the permeation flux while maintaining the wetting resistance. Dual-layer fibers with the proposed morphology have been fabricated by the dry-jet wet spinning process via careful choice of dopes composition and coagulation conditions. In addition to high energy efficiency (EE) of 94%, a superior flux of 98.6 L m(-2) h(-1) is obtained during the direct contact membrane distillation (DCMD) desalination experiments. Moreover, the liquid entry pressure (LEP) and long-term DCMD performance test show high wetting resistance and long-term stability. Mathematical modeling has been conducted to investigate the membrane mass transfer properties in terms of temperature profile and apparent diffusivity of the membranes. It is concluded that the enhancement in permeation flux arises from the coupling effect of two mechanisms; namely, a higher driving force and a lower mass transfer resistance, while the later is the major contribution. This work provides an insight on MD fundamentals and strategy to tailor making ideal membranes for DCMD application in desalination industry.

  17. Anion-conductive membranes with ultralow vanadium permeability and excellent performance in vanadium flow batteries.

    PubMed

    Mai, Zhensheng; Zhang, Huamin; Zhang, Hongzhang; Xu, Wanxing; Wei, Wenping; Na, Hui; Li, Xianfeng

    2013-02-01

    Anion exchange membranes prepared from quaternized poly(tetramethyl diphenyl ether sulfone) (QAPES) were first investigated in the context of vanadium flow battery (VFB) applications. The membranes showed an impressive suppression effect on vanadium ions. The recorded vanadium permeability was 0.02×10(-7)-0.09×10(-7) cm(2) min(-1), which was two orders of magnitude lower than that of Nafion 115. The self-discharge duration of a VFB single cell with a QAPES membrane is four times longer than that of Nafion 115. The morphological difference in hydrophilic domains between QAPES and Nafion was confirmed by TEM. After soaking the membranes in VO(2)(+) solution, adsorbed vanadium ions can barely be found in QAPES, whereas the hydrophilic domains of Nafion were stained. In the ex situ chemical stability test, QAPES showed a high tolerance to VO(2)(+) and remained intact after immersion in VO(2)(+) solution for over 250 h. The performance of a VFB single cell assembled with QAPES membranes is equal to or even better than that of Nafion 115 and remains stable in a long-term cycle test. These results indicate that QAPES membranes can be an ideal option in the fabrication of high-performance VFBs with low electric capacity loss.

  18. Performance of ceramic ultrafiltration membranes and fouling behavior of a dye-polysaccharide binary system.

    PubMed

    Zuriaga-Agustí, E; Alventosa-deLara, E; Barredo-Damas, S; Alcaina-Miranda, M I; Iborra-Clar, M I; Mendoza-Roca, J A

    2014-05-01

    Ultrafiltration membrane processes have become an established technology in the treatment and reuse of secondary effluents. Nevertheless, membrane fouling arises as a major obstacle in the efficient operation of these systems. In the current study, the performance of tubular ultrafiltration ceramic membranes was evaluated according to the roles exerted by membrane pore size, transmembrane pressure and feed concentration on a binary foulant system simulating textile wastewater. For that purpose, carboxymethyl cellulose sodium salt (CMC) and an azo dye were used as colloidal and organic foulants, respectively. Results showed that a larger pore size enabled more solutes to get adsorbed into the pores, producing a sharp permeate flux decline attributed to the rapid pore blockage. Besides, an increase in CMC concentration enhanced severe fouling in the case of the tighter membrane. Concerning separation efficiency, organic matter was almost completely removed with removal efficiency above 98.5%. Regarding the dye, 93% of rejection was achieved. Comparable removal efficiencies were attributed to the dynamic membrane formed by the cake layer, which governed process performance in terms of rejection and selectivity. As a result, none of the evaluated parameters showed significant influence on separation efficiency, supporting the significant role of cake layer on filtration process.

  19. Influence of operating conditions on ceramic ultrafiltration membrane performance when treating textile effluents.

    PubMed

    Barredo-Damas, S; Alcaina-Miranda, M I; Gemma, M; Iborra-Clar, M I; Mendoza-Roca, J A

    2011-01-01

    This work studies the performance of three commercial ceramic ultrafiltration membranes (ZrO(2)-TiO(2)) treating raw effluent from a textile industry. The effect of crossflow velocity at 3, 4 and 5 m s(-1) as well as membrane characteristics, such as molecular weight cut-off (30, 50 and 150 kDa), on process performance were studied. Experiments were carried out in concentration mode in order to observe the effect of volume reduction factor simultaneously. Results showed a combined influence of both crossflow velocity and molecular weight cut-off on flux performance. TOC and COD removals up to 70% and 84% respectively were reached. On the other hand, almost complete color (>97%) and turbidity (>99%) removals were achieved for all the membranes and operating conditions.

  20. Graphene-Coated Hollow Fiber Membrane as the Cathode in Anaerobic Electrochemical Membrane Bioreactors--Effect of Configuration and Applied Voltage on Performance and Membrane Fouling.

    PubMed

    Werner, Craig M; Katuri, Krishna P; Hari, Ananda Rao; Chen, Wei; Lai, Zhiping; Logan, Bruce E; Amy, Gary L; Saikaly, Pascal E

    2016-04-19

    Electrically conductive, graphene-coated, hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 and 0.9 V) using a new rectangular reactor configuration compared to a previous tubular design (0.7 V). The onset of biofouling was delayed and minimized in rectangular reactors operated at 0.9 V compared to those at 0.7 V due to higher rates of hydrogen production. Maximum transmembrane pressures for the rectangular reactor were only 0.10 bar (0.7 V) or 0.05 bar (0.9 V) after 56 days of operation compared to 0.46 bar (0.7 V) for the tubular reactor after 52 days. The thickness of the membrane biofouling layer was approximately 0.4 μm for rectangular reactors and 4 μm for the tubular reactor. Higher permeate quality (TSS = 0.05 mg/L) was achieved in the rectangular AnEMBR than that in the tubular AnEMBR (TSS = 17 mg/L), likely due to higher current densities that minimized the accumulation of cells in suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

  1. Membrane-attached biofilms for VOC wastewater treatment. 2: Effect of biofilm thickness on performance

    SciTech Connect

    Santos, L.M.F. dos; Livingston, A.G.

    1995-07-05

    This article reports a study of the performance of membrane-attached biofilms grown in a single tube extractive membrane bioreactor (STEMB) used for the treatment of a synthetic wastewater containing a toxic VOC (1,2-dichloroethane [DCE]). Mass balances show that complete mineralization of DCE was achieved, and that the biofilms were effective in reducing air stripping to negligible levels. Experimental results are presented showing the evolution over time of biofilm thickness and its influence on the flux of DCE across the membrane. It has been found that a trade-off exists between the positive influence of biofilms in reducing air-stripping of DCE, and the negative influence of biofilms in reducing DCE flux across the membrane. These considerations lead to an optimal biofilm thickness in the region of 200 to 400 {mu}m being recommended for this system.

  2. Aversive Pavlovian Responses Affect Human Instrumental Motor Performance

    PubMed Central

    Rigoli, Francesco; Pavone, Enea Francesco; Pezzulo, Giovanni

    2012-01-01

    In neuroscience and psychology, an influential perspective distinguishes between two kinds of behavioral control: instrumental (habitual and goal-directed) and Pavlovian. Understanding the instrumental-Pavlovian interaction is fundamental for the comprehension of decision-making. Animal studies (as those using the negative auto-maintenance paradigm), have demonstrated that Pavlovian mechanisms can have maladaptive effects on instrumental performance. However, evidence for a similar effect in humans is scarce. In addition, the mechanisms modulating the impact of Pavlovian responses on instrumental performance are largely unknown, both in human and non-human animals. The present paper describes a behavioral experiment investigating the effects of Pavlovian conditioned responses on performance in humans, focusing on the aversive domain. Results showed that Pavlovian responses influenced human performance, and, similar to animal studies, could have maladaptive effects. In particular, Pavlovian responses either impaired or increased performance depending on modulator variables such as threat distance, task controllability, punishment history, amount of training, and explicit punishment expectancy. Overall, these findings help elucidating the computational mechanisms underlying the instrumental-Pavlovian interaction, which might be at the base of apparently irrational phenomena in economics, social behavior, and psychopathology. PMID:23060738

  3. Environmental context change affects memory for performed actions.

    PubMed

    Sahakyan, Lili

    2010-03-01

    The current study investigated the effect of environmental context change between the study and test on the recall of action phrases that either were performed during encoding (subject-performed tasks, SPTs) or were verbally encoded (verbal tasks, VTs). Both SPTs and VTs showed the same magnitude of impaired recall when the study and test contexts mismatched. Furthermore, changing the context between the two study lists reduced cross-list intrusion errors compared to encoding the lists in the same context. Both SPTs and VTs benefited from studying the lists in different contexts as evidenced by reduced intrusions. Taken together, the results suggest that SPTs are integrated with their context because they suffered when context changed between the study and test, and they also benefited when they were performed in two environments versus the same environment.

  4. Wheat gluten hydrolysate affects race performance in the triathlon.

    PubMed

    Koikawa, Natsue; Aoki, Emi; Suzuki, Yoshio; Sakuraba, Keishoku; Nagaoka, Isao; Aoki, Kazuhiro; Shimmura, Yuki; Sawaki, Keisuke

    2013-07-01

    Wheat gluten hydrolysate (WGH) is a food ingredient, prepared by partial enzymatic digestion of wheat gluten, which has been reported to suppress exercise-induced elevation of serum creatinine kinase (CK) activity. However, its effects on athletic performance have not yet been elucidated. This is the presentation of an experiment performed on five female college triathletes who completed an Olympic distance triathlon with or without ingestion of 21 g of WGH during the cycling leg. The experiment was performed in a crossover double-blind manner. The race time of the running leg and thus the total race time was significantly shorter when WGH was ingested. However, serum CK levels exhibited no apparent differences between the two WGH or placebo groups.

  5. When children affect parents: Children's academic performance and parental investment.

    PubMed

    Yurk Quadlin, Natasha

    2015-07-01

    Sociologists have extensively documented the ways that parent resources predict children's achievement. However, less is known about whether and how children's academic performance shapes parental investment behaviors. I use data from the Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS-K) and longitudinal fixed effects models to examine how changes in teacher assessments are related to changes in the conferral of various parent resources. Overall, I find that the relationship between achievement and investment varies based on the directionality in children's achievement and the type of resource at hand. Children whose performance improves receive a broad range of enrichment resources, while declines in performance are met with corrective educational resources. Results are largely consistent whether language or math assessments are used to predict investment, and also among children whose achievement does not change over time. I discuss these patterns, along with implications for the use of parent resources in education and family research.

  6. Performance enhancement with powdered activated carbon (PAC) addition in a membrane bioreactor (MBR) treating distillery effluent.

    PubMed

    Satyawali, Yamini; Balakrishnan, Malini

    2009-10-15

    This work investigated the effect of powdered activated carbon (PAC) addition on the operation of a membrane bioreactor (MBR) treating sugarcane molasses based distillery wastewater (spentwash). The 8L reactor was equipped with a submerged 30 microm nylon mesh filter with 0.05 m(2) filtration area. Detailed characterization of the commercial wood charcoal based PAC was performed before using it in the MBR. The MBR was operated over 200 days at organic loading rates (OLRs) varying from 4.2 to 6.9 kg m(-3)d(-1). PAC addition controlled the reactor foaming during start up and enhanced the critical flux by around 23%; it also prolonged the duration between filter cleaning. Operation at higher loading rates was possible and for a given OLR, the chemical oxygen demand (COD) removal was higher with PAC addition. However, biodegradation in the reactor was limited and the high molecular weight compounds were not affected by PAC supplementation. The functional groups on PAC appear to interact with the polysaccharide portion of the sludge, which may reduce its propensity to interact with the nylon mesh.

  7. Mechanics and molecular filtration performance of graphyne nanoweb membranes for selective water purification

    NASA Astrophysics Data System (ADS)

    Lin, Shangchao; Buehler, Markus J.

    2013-11-01

    Two-dimensional carbon materials such as the 2D nanoweb-like graphyne membrane are promising as molecular sieves for energy and environmental applications. Based on the application of water purification - the removal of contaminants from wastewater and seawater - here we use molecular dynamics (MD) simulations to investigate the interplay between mechanical forces, filtration mechanisms, and overall performance for graphyne membranes with different pore sizes. We carry out biaxial tensile tests and verify the superior mechanical robustness and tolerance of graphyne membranes against possible deformations from the membrane installation process. A possible ultimate stress in excess of 15 GPa and an ultimate strain of 1.2-2.7% are determined. We also demonstrate their excellent filtration performance with barrier-free water permeation and perfect rejection of the representative contaminants considered here, including divalent heavy metal salts (copper sulfate), hydrophobic organic chemicals (benzene and carbon tetrachloride), and inorganic monovalent salts (sodium chloride). We find that graphtriyne, with an effective pore diameter of 3.8 Å, exhibits an optimal purification performance, because the contaminant rejection rate is more sensitive to pore size than water permeability. In addition, we find that the hydrophobic graphyne membranes exhibit higher rejection rates for hydrophilic contaminants compared to the hydrophobic ones. This size exclusion effect is a result of the larger hydrated radii of hydrophilic species due to stronger interactions between them and water molecules. Finally, we find that the maximum deformation of graphtriyne at the ultimate strain before material failure has only a minor impact on its filtration performance. One of the advantages of using graphyne for water purification is that no chemical functionalization or defects need to be introduced, which maintains the structural integrity of the membrane, and possibly, the long-term device

  8. Teacher Dispositions Affecting Self-Esteem and Student Performance

    ERIC Educational Resources Information Center

    Helm, Carroll

    2007-01-01

    Research supports several factors related to student success. Darling-Hammond (2000) indicated that the quality of teachers, as measured by whether the teachers were fully certified and had a major in their teaching field, was related to student performance. Measures of teacher preparation and certification were the strongest predictors of student…

  9. Factors Affecting Student Performance in Law School Economics Courses.

    ERIC Educational Resources Information Center

    Siegfried, John J.

    1981-01-01

    Noting the increasing role of economics in the law, many law schools have introduced formal economics instruction into their curricula. Several of the controversies surrounding liberal arts courses taught in law schools are examined. Prior formal coursework in the subject appeared to have no relationship to course performance. (MLW)

  10. Factors Affecting School District Performance Scores in Louisiana

    ERIC Educational Resources Information Center

    Harrison, Ronnie

    2010-01-01

    The purpose of this study was to investigate the relationship between District Performance Scores (DPS) in Louisiana and (a) socio-economic status of students, (b) academic achievement using average ACT scores, (c) percentage of certified teachers, (d) district class size, (e) per pupil expenditure, and (f) percentage of minority students in…

  11. Performativity and Affectivity: Lesson Observations in England's Further Education Colleges

    ERIC Educational Resources Information Center

    Edgington, Ursula

    2013-01-01

    Teaching and learning observations (TLOs) are used in educational environments worldwide to measure and improve quality and support professional development. TLOs can be positive for teachers who enjoy opportunities to "perform" their craft and/or engage in professional dialogue. However, if this crucial, collaborative developmental…

  12. Does Participative Decision Making Affect Lecturer Performance in Higher Education?

    ERIC Educational Resources Information Center

    Sukirno, D. S.; Siengthai, Sununta

    2011-01-01

    Purpose: The relationship between participation and job performance has captured the interest of not only business researchers but also education researchers. However, the topic has not gained significant attention in the educational management research arena. The purpose of this paper is to empirically examine the impact of participation in…

  13. How Motivation Affects Academic Performance: A Structural Equation Modelling Analysis

    ERIC Educational Resources Information Center

    Kusurkar, R. A.; Ten Cate, Th. J.; Vos, C. M. P.; Westers, P.; Croiset, G.

    2013-01-01

    Few studies in medical education have studied effect of quality of motivation on performance. Self-Determination Theory based on quality of motivation differentiates between Autonomous Motivation (AM) that originates within an individual and Controlled Motivation (CM) that originates from external sources. To determine whether Relative Autonomous…

  14. Unit Cohesion and the Surface Navy: Does Cohesion Affect Performance

    DTIC Science & Technology

    1989-12-01

    Relationship of Group Cohe- sion to Group Performance: A Research Integration Attempt, by L. W. Oliver, A199069, July 1988. Cartwright , D., "The Nature of...Group Cohesiveness," in Darwin Cart- wright and Alvin Zander, eds., Group Dynamics: Research and Theory, New York: Harper and Row, 1968. Gujarati, D. N

  15. Fluid and solute transfer characteristics in a dialyzer with a high-performance membrane.

    PubMed

    Mineshima, Michio

    2011-01-01

    To date, many types of high-flux dialyzers with high-performance membranes have been developed. They seem to have a higher internal filtration flow rate (Q(IF)) because of a higher ultrafiltration coefficient. In the health reimbursement system in Japan, commercially available dialyzers are categorized into five types based on their β(2)-microglobulin clearance (K(BMG)) values. Although the K(BMG) value was not correlated strongly with the Q(IF) value for 26 types of commercially available dialyzers, almost all the dialyzers with a higher Q(IF) value had a higher KBMG value. These dialyzers seem to have a higher convective transport because of internal filtration in addition to diffusive transport. We measured the blood flow velocity in a cross-sectional plane of the dialyzer using pulse Doppler ultra-sonography to evaluate QIF. It is a useful method for the bedside monitoring because it is noninvasive to the patient and produces reliable data with a higher reproducibility. On the other hand, membrane fouling occurs more easily in higher Q(IF) dialyzers, compared with conventional dialyzers, because of the higher degree of membrane fouling. Internal filtration-enhanced hemodialysis (IFEHD) using these dialyzers, therefore, has the advantage of increasing solute removal efficiency by enhancing convective transport and the simultaneous disadvantage of decreasing solute removal efficiency by causing membrane fouling. Thus, IFEHD treatment should be performed using a dialyzer with a high-performance membrane to ensure that the advantage is superior to the disadvantage.

  16. Temperature-dependent gas transport performance of vertically aligned carbon nanotube/parylene composite membranes.

    PubMed

    Zhang, Lei; Yang, Junhe; Wang, Xianying; Zhao, Bin; Zheng, Guangping

    2014-01-01

    A novel composite membrane consisting of vertically aligned carbon nanotubes (CNTs) and parylene was successfully fabricated. Seamless filling of the spaces in CNT forests with parylene was achieved by a low-pressure chemical vapor deposition (CVD) technique and followed with the Ar/O2 plasma etching to expose CNT tips. Transport properties of various gases through the CNT/parylene membranes were explored. And gas permeances were independent on feed pressure in accordance with the Knudsen model, but the permeance values were over 60 times higher than that predicted by the Knudsen diffusion kinetics, which was attributed to specular momentum reflection inside smooth CNT pores. Gas permeances and enhancement factors over the Knudsen model firstly increased and then decreased with rising temperature, which confirmed the existence of non-Knudsen transport. And surface adsorption diffusion could affect the gas permeance at relatively low temperature. The gas permeance of the CNT/parylene composite membrane could be improved by optimizing operating temperature.

  17. Does familiarity with computers affect computerized neuropsychological test performance?

    PubMed

    Iverson, Grant L; Brooks, Brian L; Ashton, V Lynn; Johnson, Lynda G; Gualtieri, C Thomas

    2009-07-01

    The purpose of this study was to determine whether self-reported computer familiarity is related to performance on computerized neurocognitive testing. Participants were 130 healthy adults who self-reported whether their computer use was "some" (n = 65) or "frequent" (n = 65). The two groups were individually matched on age, education, sex, and race. All completed the CNS Vital Signs (Gualtieri & Johnson, 2006b) computerized neurocognitive battery. There were significant differences on 6 of the 23 scores, including scores derived from the Symbol-Digit Coding Test, Stroop Test, and the Shifting Attention Test. The two groups were also significantly different on the Psychomotor Speed (Cohen's d = 0.37), Reaction Time (d = 0.68), Complex Attention (d = 0.40), and Cognitive Flexibility (d = 0.64) domain scores. People with "frequent" computer use performed better than people with "some" computer use on some tests requiring rapid visual scanning and keyboard work.

  18. Scales affect performance of Monarch butterfly forewings in autorotational flight

    NASA Astrophysics Data System (ADS)

    Demko, Anya; Lang, Amy

    2012-11-01

    Butterfly wings are characterized by rows of scales (approximately 100 microns in length) that create a shingle-like pattern of cavities over the entire surface. It is hypothesized that these cavities influence the airflow around the wing and increase aerodynamic performance. A forewing of the Monarch butterfly (Danus plexippus) naturally undergoes autorotational flight in the laminar regime. Autorotational flight is an accurate representation of insect flight because the rotation induces a velocity gradient similar to that found over a flapping wing. Drop test flights of 22 forewings before and after scale removal were recorded with a high-speed camera and flight behavior was quantified. It was found that removing the scales increased the descent speed and decreased the descent factor, a measure of aerodynamic efficacy, suggesting that scales increased the performance of the forewings. Funded by NSF REU Grant 1062611.

  19. Neuroticism Negatively Affects Multitasking Performance through State Anxiety

    DTIC Science & Technology

    2009-02-01

    interruptions, is greater than ever. As a result, multitasking has become a necessity in both home and work life for many individuals (e.g., Bühner...at work and at home . As such, researchers have begun to focus attention on understanding and predicting multitasking performance. Though past...technological innovation, and information overload, the pace of life is rapidly increasing. The pressure to do more in less time, often with frequent

  20. Personality Factors Affecting Pilot Combat Performance: A Preliminary Investigation

    DTIC Science & Technology

    1997-09-01

    collected by personnel from Metrica , Inc., under Contract F33615-91-D-0010 (Delivery Order 0005) sponsored by the Air Force Armstrong Laboratory. The...authors would like to thank ’their colleagues at Metrica for their contributions to . this effort; in particular, Mr John Quebe and Mr Martin Dittmar...aircrew combat performance. San Antonio TX: Metrica Inc. 7 . Dolgin, D.L., & Gibb, G.D. (1988). Personality assessment in aviator selection (NAMRL

  1. Luminance controlled pupil size affects Landolt C task performance

    SciTech Connect

    Berman, S.M. ); Fein, G. ); Jewett, D.L.; Ashford, F. )

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m[sup 2] and 73 cd/m[sup 2]. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  2. Luminance controlled pupil size affects Landolt C task performance. Revision

    SciTech Connect

    Berman, S.M.; Fein, G.; Jewett, D.L.; Ashford, F.

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m{sup 2} and 73 cd/m{sup 2}. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  3. Factors That Affect Academic Performance Among Pharmacy Students

    PubMed Central

    Sansgiry, Sujit S.; Bhosle, Monali; Sail, Kavita

    2006-01-01

    Objective The objective of this study was to examine factors such as academic competence, test competence, time management, strategic studying, and test anxiety, and identify whether these factors could distinguish differences among students, based on academic performance and enrollment in the experiential program. Methods A cross-sectional study design utilizing questionnaires measuring previously validated constructs was used to evaluate the effect of these factors on students with low and high cumulative grade point averages (GPAs). Pharmacy students (N = 198) enrolled at the University of Houston participated in the study. Results Academic performance was significantly associated with factors such as academic competence and test competence. Students with a cumulative GPA of 3.0 or greater significantly differed in their level of test competence than those with a GPA of less than 3.0. Students enrolled in their experiential year differed from students enrolled in their second year of curriculum on factors such as test anxiety, academic competence, test competence, and time management skills. Conclusion Test competence was an important factor to distinguish students with low vs. high academic performance. Factors such as academic competence, test competence, test anxiety and time management improve as students' progress in their experiential year. PMID:17149433

  4. Characterization of EVA/clay nanocomposite membranes and its pervaporation performance.

    PubMed

    Anilkumar, S; Kumaran, M G; Thomas, Sabu

    2008-04-03

    Pervaporation separation of chlorinated hydrocarbon/acetone mixtures has been investigated using nanoclay modified poly(ethylene-co-vinyl acetate) films. The results have been compared with the unfilled poly(ethylene-co-vinyl acetate) films. The nanoclay modified membranes were characterized by X-ray diffraction technique. The dispersion of layered silicates in the polymer matrix was analyzed using transmission electron microscopy. The nanoclay showed excellent dispersion in the polymer matrix. The effect of free volume on the pervaporation performance was investigated by positron annihilation lifetime spectroscopy. Poly(ethylene-co-vinyl acetate) nanocomposite membrane showed high selectivity because of the plateletlike morphology and high aspect ratio of layered silicates. The nano clay content and the swelling effects on pervaporation performance of nano composite membranes have been investigated in detail.

  5. Graphene Oxide Quantum Dots Covalently Functionalized PVDF Membrane with Significantly-Enhanced Bactericidal and Antibiofouling Performances

    PubMed Central

    Zeng, Zhiping; Yu, Dingshan; He, Ziming; Liu, Jing; Xiao, Fang-Xing; Zhang, Yan; Wang, Rong; Bhattacharyya, Dibakar; Tan, Timothy Thatt Yang

    2016-01-01

    Covalent bonding of graphene oxide quantum dots (GOQDs) onto amino modified polyvinylidene fluoride (PVDF) membrane has generated a new type of nano-carbon functionalized membrane with significantly enhanced antibacterial and antibiofouling properties. A continuous filtration test using E. coli containing feedwater shows that the relative flux drop over GOQDs modified PVDF is 23%, which is significantly lower than those over pristine PVDF (86%) and GO-sheet modified PVDF (62%) after 10 h of filtration. The presence of GOQD coating layer effectively inactivates E. coli and S. aureus cells, and prevents the biofilm formation on the membrane surface, producing excellent antimicrobial activity and potentially antibiofouling capability, more superior than those of previously reported two-dimensional GO sheets and one-dimensional CNTs modified membranes. The distinctive antimicrobial and antibiofouling performances could be attributed to the unique structure and uniform dispersion of GOQDs, enabling the exposure of a larger fraction of active edges and facilitating the formation of oxidation stress. Furthermore, GOQDs modified membrane possesses satisfying long-term stability and durability due to the strong covalent interaction between PVDF and GOQDs. This study opens up a new synthetic avenue in the fabrication of efficient surface-functionalized polymer membranes for potential waste water treatment and biomolecules separation. PMID:26832603

  6. Fluid-Structure interaction analysis and performance evaluation of a membrane blade

    NASA Astrophysics Data System (ADS)

    Saeedi, M.; Wüchner, R.; Bletzinger, K.-U.

    2016-09-01

    Examining the potential of a membrane blade concept is the goal of the current work. In the sailwing concept the surface of the wing, or the blade in this case, is made from pre-tensioned membranes which meet at the pre-tensioned edge cable at the trailing edge. Because of the dependency between membrane deformation and applied aerodynamic load, two-way coupled fluid-structure interaction analysis is necessary for evaluation of the aerodynamic performance of such a configuration. The in-house finite element based structural solver, CARAT++, is coupled with OpenFOAM in order to tackle the multi-physics problem. The main aerodynamic characteristics of the membrane blade including lift coefficient, drag coefficient and lift to drag ratio are compared with its rigid counterpart. A single non-rotating NREL phase VI blade is studied here as a first step towards analyzing the concept for the rotating case. Compared with the rigid blade, the membrane blade has a higher slope of the lift curve. For higher angles of attack, lift and drag coefficients as well as the lift to drag ratio is higher for the membrane blade. A single non-rotating blade is studied here as a first step towards analyzing the concept for the rotating case.

  7. SAPO-34 Membranes for N-2/CH4 separation: Preparation, characterization, separation performance and economic evaluation

    SciTech Connect

    Li, SG; Zong, ZW; Zhou, SJ; Huang, Y; Song, ZN; Feng, XH; Zhou, RF; Meyer, HS; Yu, M; Carreon, MA

    2015-08-01

    SAPO-34 membranes were synthesized by several routes towards N-2/CH4 separation. Membrane synthesis parameters including water content in the gel, crystallization time, support pore size, and aluminum source were investigated. High performance N-2-selective membranes were obtained on 100-nm-pore alumina tubes by using Al(i-C3H7O)(3) as aluminum source with a crystallization time of 6 h. These membranes separated N-2 from CH, with N-2 permeance as high as 500 GPU with separation selectivity of 8 at 24 degrees C. for a 50/50 N-2/CH4 mixture. Nitrogen and CH, adsorption isotherms were measured on SAPO-34 crystals. The N-2 and CH, heats of adsorption were 11 and 15 kJ/mol, respectively, which lead to a preferential adsorption of CE-H-4 over N-2 in the N-2/CH4 mixture. Despite this, the SAPO-34 membranes were selective for N-2 over CH4 in the mixture because N-2 diffuses much faster than CH4 and differences in diffusivity played a more critical role than the competitive adsorption. Preliminary economic evaluation indicates that the required N-2/CH4 selectivity would be 15 in order to maintain a CH4 loss below 10%. For small nitrogen-contaminated gas wells, our current SAPO-34 membranes have potential to compete with the benchmark technology cryogenic distillation for N-2 rejection. (C) 2015 Elsevier B.V. All rights reserved,

  8. Graphene Oxide Quantum Dots Covalently Functionalized PVDF Membrane with Significantly-Enhanced Bactericidal and Antibiofouling Performances

    NASA Astrophysics Data System (ADS)

    Zeng, Zhiping; Yu, Dingshan; He, Ziming; Liu, Jing; Xiao, Fang-Xing; Zhang, Yan; Wang, Rong; Bhattacharyya, Dibakar; Tan, Timothy Thatt Yang

    2016-02-01

    Covalent bonding of graphene oxide quantum dots (GOQDs) onto amino modified polyvinylidene fluoride (PVDF) membrane has generated a new type of nano-carbon functionalized membrane with significantly enhanced antibacterial and antibiofouling properties. A continuous filtration test using E. coli containing feedwater shows that the relative flux drop over GOQDs modified PVDF is 23%, which is significantly lower than those over pristine PVDF (86%) and GO-sheet modified PVDF (62%) after 10 h of filtration. The presence of GOQD coating layer effectively inactivates E. coli and S. aureus cells, and prevents the biofilm formation on the membrane surface, producing excellent antimicrobial activity and potentially antibiofouling capability, more superior than those of previously reported two-dimensional GO sheets and one-dimensional CNTs modified membranes. The distinctive antimicrobial and antibiofouling performances could be attributed to the unique structure and uniform dispersion of GOQDs, enabling the exposure of a larger fraction of active edges and facilitating the formation of oxidation stress. Furthermore, GOQDs modified membrane possesses satisfying long-term stability and durability due to the strong covalent interaction between PVDF and GOQDs. This study opens up a new synthetic avenue in the fabrication of efficient surface-functionalized polymer membranes for potential waste water treatment and biomolecules separation.

  9. Graphene Oxide Quantum Dots Covalently Functionalized PVDF Membrane with Significantly-Enhanced Bactericidal and Antibiofouling Performances.

    PubMed

    Zeng, Zhiping; Yu, Dingshan; He, Ziming; Liu, Jing; Xiao, Fang-Xing; Zhang, Yan; Wang, Rong; Bhattacharyya, Dibakar; Tan, Timothy Thatt Yang

    2016-02-02

    Covalent bonding of graphene oxide quantum dots (GOQDs) onto amino modified polyvinylidene fluoride (PVDF) membrane has generated a new type of nano-carbon functionalized membrane with significantly enhanced antibacterial and antibiofouling properties. A continuous filtration test using E. coli containing feedwater shows that the relative flux drop over GOQDs modified PVDF is 23%, which is significantly lower than those over pristine PVDF (86%) and GO-sheet modified PVDF (62%) after 10 h of filtration. The presence of GOQD coating layer effectively inactivates E. coli and S. aureus cells, and prevents the biofilm formation on the membrane surface, producing excellent antimicrobial activity and potentially antibiofouling capability, more superior than those of previously reported two-dimensional GO sheets and one-dimensional CNTs modified membranes. The distinctive antimicrobial and antibiofouling performances could be attributed to the unique structure and uniform dispersion of GOQDs, enabling the exposure of a larger fraction of active edges and facilitating the formation of oxidation stress. Furthermore, GOQDs modified membrane possesses satisfying long-term stability and durability due to the strong covalent interaction between PVDF and GOQDs. This study opens up a new synthetic avenue in the fabrication of efficient surface-functionalized polymer membranes for potential waste water treatment and biomolecules separation.

  10. Biofilm development in a membrane-aerated biofilm reactor: effect of flow velocity on performance.

    PubMed

    Casey, E; Glennon, B; Hamer, G

    2000-02-20

    The effect of liquid flow velocity on biofilm development in a membrane-aerated biofilm reactor was investigated both by mathematical modeling and by experiment, using Vibrio natriegens as a test organism and acetate as carbon substrate. It was shown that velocity influenced mass transfer in the diffusion boundary layer, the biomass detachment rate from the biofilm, and the maximum biofilm thickness attained. Values of the overall mass transfer coefficient of a tracer through the diffusion boundary layer, the biofilm, and the membrane were shown to be identical during different experiments at the maximum biofilm thickness. Comparison of the results with published values of this parameter in membrane attached biofilms showed a similar trend. Therefore, it was postulated that this result might indicate the mechanism that determines the maximum biofilm thickness in membrane attached biofilms. In a series of experiments, where conditions were set so that the active layer of the membrane attached biofilm was located close to the membrane biofilm interface, it was shown that the most critical effect on process performance was the effect of velocity on biofilm structure. Biofilm thickness and effective diffusivity influenced reaction and diffusion in a complex manner such that the yield of biomass on acetate was highly variable. Consideration of endogenous respiration in the mathematical model was validated by direct experimental measurements of yield coefficients. Good agreement between experimental measurements of acetate and oxygen uptake rates and their prediction by the mathematical model was achieved.

  11. Positive affective tone and team performance: The moderating role of collective emotional skills.

    PubMed

    Collins, Amy L; Jordan, Peter J; Lawrence, Sandra A; Troth, Ashlea C

    2016-01-01

    Research on affect as a group-level phenomenon has shown that over time, individual members within a group become highly similar in their affect (i.e., members experience and display similar emotions and moods), and often become similar enough that the aggregation of individuals' affect can meaningfully represent the "affective tone" of the group. It is generally assumed that a more positive affective tone will lead to better team performance. We challenge the conclusion that positive affective tone is always good for team performance, suggesting that the relationship between positive affective tone and team performance is subject to moderating influences. Across two studies, we demonstrate that the self-reported collective emotional skills of team members play a crucial role in determining whether positive affective tone is beneficial or detrimental to team performance. Implications for theory and practice are discussed.

  12. Fabrication of SnO2 Asymmetric Membranes for High Performance Lithium Battery Anode.

    PubMed

    Wu, Ji; Chen, Hao; Byrd, Ian; Lovelace, Shavonne; Jin, Congrui

    2016-06-08

    Alloy electrode material like tin dioxide (SnO2) possesses much higher specific capacity as compared to commercial graphite anode in lithium ion battery (783 vs 372 mAh g(-1)). However, the huge volume change (260%) of SnO2-based anode during the alloying and dealloying process can cause significant electrode pulverization and rapid capacity loss. Herein we report the synthesis of SnO2 asymmetric membranes via a unique combination of phase inversion and sol-gel chemistry to overcome this big challenge. The SnO2 asymmetric membrane electrode demonstrates a specific capacity of 500 mAh g(-1) based on the overall electrode mass at a current density of 280 mA g(-1) (∼0.5C) with >96% capacity retention after 400 cycles. When the current density is increased from 28 to 560 mA g(-1), its overall capacity is only reduced by 36%. Such an outstanding rate and cycling performance is attributed to the existence of networking porous structure in the membrane that can provide high electrical conductivity, multiple diffusion channels, and free volumes for electrode expansion. The carbonization temperature has a dramatic impact on the electrode performance. Membranes carbonized at 500 °C show an excellent cycling performance, whereas the capacity of the membrane carbonized at 800 °C decreases by 51% in 100 cycles. Such a drastic difference in cycle life is caused by the reduction of small SnO2 NPs (∼3.9 nm) into large metallic tin spheres (∼40 nm) at 800 °C. This is the first original report on using asymmetric membrane structure to stabilize an SnO2-based lithium ion battery anode with an excellent electrochemical performance.

  13. Characterization of titanium dioxide: Factors affecting photocatalytic performance

    SciTech Connect

    Presley, R.W.

    1995-06-01

    Titanium dioxide is being evaluated as a photocatalyst in the destruction of contaminants in aqueous waste streams. Commercial samples of TiO{sub 2} powder have been obtained for base line studies of the photocatalytic destruction of salicylic acid standards. These commercial samples have been prepared by flame hydrolysis and aerosol or spray pyrolysis. Additional samples of TiO{sub 2} have been prepared in house by precipitation from TiCl{sub 4} in aqueous solution, some with the addition of dopants. X-ray powder diffraction data analysis indicates the predominate phase of these commercial and prepared powders to be anatase. A minor amount of the rutile crystalline phase of TiO{sub 2} was observed at various levels in some of these catalysts. The broadness of the x-ray diffraction bands varied among the samples analyzed and indicated the primary particle size to be within the 500 to 1,000 angstrom range with the product produced in house having the smallest crystallite size. Experiments were then performed to assess the photocatalytic performance of these various types of catalyst in the destruction of 30 ppm salicylic acid in deionized water.

  14. Elevated Performance of Thin Film Nanocomposite Membranes Enabled by Modified Hydrophilic MOFs for Nanofiltration.

    PubMed

    Zhu, Junyong; Qin, Lijuan; Uliana, Adam; Hou, Jingwei; Wang, Jing; Zhang, Yatao; Li, Xin; Yuan, Shushan; Li, Jian; Tian, Miaomiao; Lin, Jiuyang; Van der Bruggen, Bart

    2017-01-18

    Metal-organic frameworks (MOFs) are studied for the design of advanced nanocomposite membranes, primarily due to their ultrahigh surface area, regular and highly tunable pore structures, and favorable polymer affinity. However, the development of engineered MOF-based membranes for water treatment lags behind. Here, thin-film nanocomposite (TFN) membranes containing poly(sodium 4-styrenesulfonate) (PSS) modified ZIF-8 (mZIF) in a polyamide (PA) layer were constructed via a facile interfacial polymerization (IP) method. The modified hydrophilic mZIF nanoparticles were evenly dispersed into an aqueous solution comprising piperazine (PIP) monomers, followed by polymerizing with trimesoyl chloride (TMC) to form a composite PA film. FT-IR spectroscopy and XPS analyses confirm the presence of mZIF nanoparticles on the top layer of the membranes. SEM and AFM images evince a retiform morphology of the TFN-mZIF membrane surface, which is intimately linked to the hydrophilicity and adsorption capacity of mZIF nanoparticles. Furthermore, the effect of different ZIF-8 loadings on the overall membrane performance was studied. Introducing the hydrophilizing mZIF nanoparticles not only furnishes the PA layer with a better surface hydrophilicity and more negative charge but also more than doubles the original water permeability, while maintaining a high retention of Na2SO4. The ultrahigh retentions of reactive dyes (e.g., reactive black 5 and reactive blue 2, >99.0%) for mZIF-functionalized PA membranes ensure their superior nanofiltration performance. This facile, cost-effective strategy will provide a useful guideline to integrate with other modified hydrophilic MOFs to design nanofiltration for water treatment.

  15. Gas Separation Membranes Derived from High-Performance Immiscible Polymer Blends Compatibilized with Small Molecules.

    PubMed

    Panapitiya, Nimanka P; Wijenayake, Sumudu N; Nguyen, Do D; Huang, Yu; Musselman, Inga H; Balkus, Kenneth J; Ferraris, John P

    2015-08-26

    An immiscible polymer blend comprised of high-performance copolyimide 6FDA-DAM:DABA(3:2) (6FDD) and polybenzimidazole (PBI) was compatibilized using 2-methylimidazole (2-MI), a commercially available small molecule. Membranes were fabricated from blends of 6FDD:PBI (50:50) with and without 2-MI for H2/CO2 separations. The membranes demonstrated a matrix-droplet type microstructure as evident with scanning electron microscopy (SEM) imaging where 6FDD is the dispersed phase and PBI is the continuous phase. In addition, membranes with 2-MI demonstrated a uniform microstructure as observed by smaller and more uniformly dispersed 6FDD domains in contrast to 6FDD:PBI (50:50) blend membranes without 2-MI. This compatibilization effect of 2-MI was attributed to interfacial localization of 2-MI that lowers the interfacial energy similar to a surfactant. Upon the incorporation of 2-MI, the H2/CO2 selectivity improved remarkably, compared to the pure blend, and surpassed the Robeson's upper bound. To our knowledge, this is the first report of the use of a small molecule to compatibilize a high-performance immiscible polymer blend. This approach could afford a novel class of membranes in which immiscible polymer blends can be compatibilized in an economical and convenient fashion.

  16. Investigation of Factors Affecting Aerodynamic Performance of Nebulized Nanoemulsion

    PubMed Central

    Kamali, Hosein; Abbasi, Shayan; Amini, Mohammad Ali; Amani, Amir

    2016-01-01

    This work aimed to prepare a nanoemulsion preparation containing budesonide and assess its aerodynamic behavior in comparison with suspension of budesonide. In-vitro aerodynamic performance of the corresponding micellar solution (ie. nanoemulsion preparation without oil) was investigated too. Nanoemulsions of almond oil containing budesonide, as a hydrophobic model drug molecule, were prepared and optimized. Then, the effect of variation of surfactant/co-surfactant concentration on the aerodynamic properties of the nebulized aerosol was studied. The results indicated that the most physically stable formulation makes the smallest aerodynamic size. The concentration of co-surfactant was also shown to be critical in determination of aerodynamic size. Furthermore, the optimized sample, with 3% w/w almond oil, 20% w/w Tween 80+Span 80 and 2% w/w ethanol showed a smaller MMAD in comparison with the commercially available suspension and the micellar solution. PMID:28243265

  17. Prepartum nutritional strategy affects reproductive performance in dairy cows.

    PubMed

    Cardoso, F C; LeBlanc, S J; Murphy, M R; Drackley, J K

    2013-09-01

    Negative energy balance during early postpartum is associated with reduced reproductive performance in dairy cows. A pooled statistical analysis of 7 studies completed in our group from 1993 to 2010 was conducted to investigate the association between prepartum energy feeding regimen and reproductive performance. The interval from calving to pregnancy (days to pregnancy, DTP) was the dependent variable to assess reproductive performance. Individual data for 408 cows (354 multiparous and 54 primiparous) were included in the analysis. The net energy for lactation (NEL) intake was determined from each cow's average dry matter intake and calculated dietary NEL density. Treatments applied prepartum were classified as either controlled-energy (CE; limited NEL intake to ≤100% of requirement) or high-energy (HE; cows were allowed to consume >100%) diets fed during the far-off (FO) or close-up (CU) dry periods. Cow was the experimental unit. The Cox proportional hazard model revealed that days to pregnancy was shorter for CE (median=157 d) than HE (median=167 d) diets during the CU period [hazard ratio (HR)=0.70]. Cows fed HE diets during the last 4 wk prepartum lost more body condition score in the first 6 wk postpartum than those fed CE diets (-0.43 and -0.30, respectively). Cows fed CE diets during the FO period had lower nonesterified fatty acids concentrations in wk 1, 2, and 3 of lactation than cows fed HE diets. Higher nonesterified fatty acids concentration in wk 1 postpartum was associated with a greater probability of disease (n=251; odds ratio=1.18). Cows on the CE regimen during the FO period had greater plasma glucose concentrations during wk 1 and 3 after calving than cows fed the HE regimen. Higher plasma glucose (HG) concentration compared with lower glucose (LG) in wk 3 (HG: n=154; LG: n=206) and wk 4 (HG: n=71; LG: n=254) after calving was associated with shorter days to pregnancy (wk 3: median=151 and 171 d for HG and LG, respectively, and HR=1.3; wk 4

  18. Factors affecting the performance of large-aperture microphone arrays.

    PubMed

    Silverman, Harvey F; Patterson, William R; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m x 8 m x 3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  19. Factors affecting the performance of large-aperture microphone arrays

    NASA Astrophysics Data System (ADS)

    Silverman, Harvey F.; Patterson, William R.; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m×8 m×3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  20. α- tocopherol’s location in membranes is not affected by their composition

    SciTech Connect

    Marquardt, Drew; Kucerka, Norbert; Katsaras, John; Harroun, Thad A.

    2014-10-15

    To this day, α-tocopherol's (aToc) role in humans is not well known. In previous studies, we have tried to connect aToc's biological function with its location in a-lipid bilayer. In the present study, we have determined, by means of small-angle neutron diffraction, that not only is aToc's hydroxyl group located high in the membrane but its tail also resides far from the center of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers. In addition, we located aToc's hydroxyl group above the lipid backbone in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and Sphingomyelin bilayers, suggesting that aToc's location near the lipid water interface may be a universal property of vitamin E. Lastly, in light of these data, how aToc efficiently terminates lipid hydroperoxy radicals at the membrane center remains an open question.

  1. α- tocopherol’s location in membranes is not affected by their composition

    DOE PAGES

    Marquardt, Drew; Kucerka, Norbert; Katsaras, John; ...

    2014-10-15

    To this day, α-tocopherol's (aToc) role in humans is not well known. In previous studies, we have tried to connect aToc's biological function with its location in a-lipid bilayer. In the present study, we have determined, by means of small-angle neutron diffraction, that not only is aToc's hydroxyl group located high in the membrane but its tail also resides far from the center of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers. In addition, we located aToc's hydroxyl group above the lipid backbone in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and Sphingomyelin bilayers, suggesting that aToc's location near the lipid water interface may be a universal propertymore » of vitamin E. Lastly, in light of these data, how aToc efficiently terminates lipid hydroperoxy radicals at the membrane center remains an open question.« less

  2. Static Magnetic Field Attenuates Lipopolysaccharide-Induced Inflammation in Pulp Cells by Affecting Cell Membrane Stability

    PubMed Central

    Tsao, Jeng-Ting; Lee, Lin-Wen; Lin, Che-Tong

    2015-01-01

    One of the causes of dental pulpitis is lipopolysaccharide- (LPS-) induced inflammatory response. Following pulp tissue inflammation, odontoblasts, dental pulp cells (DPCs), and dental pulp stem cells (DPSCs) will activate and repair damaged tissue to maintain homeostasis. However, when LPS infection is too serious, dental repair is impossible and disease may progress to irreversible pulpitis. Therefore, the aim of this study was to examine whether static magnetic field (SMF) can attenuate inflammatory response of dental pulp cells challenged with LPS. In methodology, dental pulp cells were isolated from extracted teeth. The population of DPSCs in the cultured DPCs was identified by phenotypes and multilineage differentiation. The effects of 0.4 T SMF on DPCs were observed through MTT assay and fluorescent anisotropy assay. Our results showed that the SMF exposure had no effect on surface markers or multilineage differentiation capability. However, SMF exposure increases cell viability by 15%. In addition, SMF increased cell membrane rigidity which is directly related to higher fluorescent anisotropy. In the LPS-challenged condition, DPCs treated with SMF demonstrated a higher tolerance to LPS-induced inflammatory response when compared to untreated controls. According to these results, we suggest that 0.4 T SMF attenuates LPS-induced inflammatory response to DPCs by changing cell membrane stability. PMID:25884030

  3. α-Tocopherol's Location in Membranes Is Not Affected by Their Composition.

    PubMed

    Marquardt, Drew; Kučerka, Norbert; Katsaras, John; Harroun, Thad A

    2015-04-21

    To this day, α-tocopherol's (aToc) role in humans is not well known. In previous studies, we have tried to connect aToc's biological function with its location in a lipid bilayer. In the present study, we have determined, by means of small-angle neutron diffraction, that not only is aToc's hydroxyl group located high in the membrane but its tail also resides far from the center of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers. In addition, we located aToc's hydroxyl group above the lipid backbone in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and sphingomyelin bilayers, suggesting that aToc's location near the lipid-water interface may be a universal property of vitamin E. In light of these data, how aToc efficiently terminates lipid hydroperoxy radicals at the membrane center remains an open question.

  4. Noise Affects Performance on the Montreal Cognitive Assessment.

    PubMed

    Dupuis, Kate; Marchuk, Veronica; Pichora-Fuller, M Kathleen

    2016-09-01

    We investigated the effect of background noise on performance on the Montreal Cognitive Assessment (MoCA). Two groups of older adults (one with clinically normal hearing, one with hearing loss) and a younger adult group with clinically normal hearing were administered two versions of the MoCA under headphones in low and high levels of background noise. Intensity levels used to present the test were customized based on the hearing abilities of participants with hearing loss to yield a uniform level of difficulty across listeners in the high-level noise condition. Both older groups had poorer MoCA scores in noise than the younger group. Importantly, all participants had poorer MoCA scores in the high-noise (M = 22.7/30) compared to the low-noise condition (M = 25.7/30, p < .001). Results suggest that background noise in the test environment should be considered when cognitive tests are conducted and results interpreted, especially when testing older adults.

  5. Performance assessment of membrane distillation for skim milk and whey processing.

    PubMed

    Hausmann, Angela; Sanciolo, Peter; Vasiljevic, Todor; Kulozik, Ulrich; Duke, Mikel

    2014-01-01

    Membrane distillation is an emerging membrane process based on evaporation of a volatile solvent. One of its often stated advantages is the low flux sensitivity toward concentration of the processed fluid, in contrast to reverse osmosis. In the present paper, we looked at 2 high-solids applications of the dairy industry: skim milk and whey. Performance was assessed under various hydrodynamic conditions to investigate the feasibility of fouling mitigation by changing the operating parameters and to compare performance to widespread membrane filtration processes. Whereas filtration processes are hydraulic pressure driven, membrane distillation uses vapor pressure from heat to drive separation and, therefore, operating parameters have a different bearing on the process. Experimental and calculated results identified factors influencing heat and mass transfer under various operating conditions using polytetrafluoroethylene flat-sheet membranes. Linear velocity was found to influence performance during skim milk processing but not during whey processing. Lower feed and higher permeate temperature was found to reduce fouling in the processing of both dairy solutions. Concentration of skim milk and whey by membrane distillation has potential, as it showed high rejection (>99%) of all dairy components and can operate using low electrical energy and pressures (<10 kPa). At higher cross-flow velocities (around 0.141 m/s), fluxes were comparable to those found with reverse osmosis, achieving a sustainable flux of approximately 12 kg/h·m(2) for skim milk of 20% dry matter concentration and approximately 20 kg/h·m(2) after 18 h of operation with whey at 20% dry matter concentration.

  6. How neighbor canopy architecture affects target plant performance

    SciTech Connect

    Tremmel, D.C.; Bazzaz, F.A. )

    1993-10-01

    Plant competition occurs through the negative effects that individual plants have on resource availability to neighboring individuals. Therefore competition experiments need to examine how different species change resource availability to their neighbors, and how different species respond to these changes-allocationally, architecturally, and physiologically-through time. In a greenhouse study we used a model system of annuals to examine how canopies of species having differing morphologies differed in their architectures and light-interception abilities, and how different species performed when grown in these canopies. Abutilon theophrasti, Datura stramonium, and Polygonum pensylvanicum were grown as [open quotes]targets[close quotes]. Plants were grown in pots, with one target plant and four neighbor plants. Detailed measurements of neighbor canopy structure and target plant canopy architecture were made at five harvests. Species with different morphologies showed large differences in canopy structure, particularly when grass and forb species were compared. Setaria, a grass, had a more open canopy than the other species (all forbs), and was a consistently weak competitor. Overall, however, the relative effects of different neighbors on target biomass varied with target species. Target biomass was poorly correlated with neighbor biomass and leaf area, but was highly correlated with a measure of target light-interception ability that took into account both target leaf deployment and neighbor light interception. Despite clear differences among neighbor species in canopy structure and effect on light penetration, the results suggest no broad generalizations about the effects of different species as neighbors. Knowledge of morphological, physiological, and life history characteristics of both the target and neighbor species may be necessary to explain the results of their competition. 53 refs., 4 figs., 4 tabs.

  7. Effect of non-solvent additives on the morphology, pore structure, and direct contact membrane distillation performance of PVDF-CTFE hydrophobic membranes.

    PubMed

    Zheng, Libing; Wu, Zhenjun; Zhang, Yong; Wei, Yuansong; Wang, Jun

    2016-07-01

    Four common types of additives for polymer membrane preparation including organic macromolecule and micromolecule additives, inorganic salts and acids, and the strong non-solvent H2O were used to prepare poly (vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) hydrophobic flat-sheet membranes. Membrane properties including morphology, porosity, hydrophobicity, pore size and pore distribution were investigated, and the permeability was evaluated via direct contact membrane distillation (DCMD) of 3.5g/L NaCl solution in a DCMD configuration. Both inorganic and organic micromolecule additives were found to slightly influence membrane hydrophobicity. Polyethylene glycol (PEG), organic acids, LiCl, MgCl2, and LiCl/H2O mixtures were proved to be effective additives to PVDF-CTFE membranes due to their pore-controlling effects and the capacity to improve the properties and performance of the resultant membranes. The occurrence of a pre-gelation process showed that when organic and inorganic micromolecules were added to PVDF-CTFE solution, the resultant membranes presented a high interconnectivity structure. The membrane prepared with dibutyl phthalate (DBP) showed a nonporous surface and symmetrical cross-section. When H2O and LiCl/H2O mixtures were also used as additives, they were beneficial for solid-liquid demixing, especially when LiCl/H2O mixed additives were used. The membrane prepared with 5% LiCl+2% H2O achieved a flux of 24.53kg/(m(2)·hr) with 99.98% salt rejection. This study is expected to offer a reference not only for PVDF-CTFE membrane preparation but also for other polymer membranes.

  8. Exploring the synergetic effects of graphene oxide (GO) and polyvinylpyrrodione (PVP) on poly(vinylylidenefluoride) (PVDF) ultrafiltration membrane performance

    NASA Astrophysics Data System (ADS)

    Chang, Xiaojing; Wang, Zhenxing; Quan, Shuai; Xu, Yanchao; Jiang, Zaixing; Shao, Lu

    2014-10-01

    Membrane surface and cross-sectional morphology created during membrane formation is one of the most essential factors determining membrane separation performance. However, the complicated interactions between added nanoparticles and additives influencing membrane morphology and performance during building membrane architectures had been generally neglected. In this study, asymmetric PVDF composite ultrafiltration (UF) membranes containing graphene oxides (GO) were prepared by using N-methyl pyrrolidone (NMP) as solvent and polyvinylpyrrodione (PVP) as the pore forming reagent. In the first time, the effects of mutual interactions between GO and PVP on membranes surface compositions, morphology and performance were investigated in detail. The variation in chemical properties of different membranes and hydrogen bonds in the membrane containing GO and PVP were confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Atomic force microscopy (AFM), scanning electron microscopy (SEM), and contact angle (CA) were utilized to clarify the synergetic effects of GO and PVP on morphologies and surface hydrophilicity of membranes. Besides, water flux, bovine serum albumin (BSA) rejection and attenuate coefficient were also determined to investigate filtration performance of various membranes. Compared with pure PVDF membrane, the comprehensive performance of PVDF/GO/PVP membrane has been obviously improved. The surface hydrophilicity and anti-fouling performance were enhanced by the synergistic effects of incorporated GO and PVP. When the PVP content was 0.25 wt.% and the GO content was 0.5 wt.%, the optimized performance can be obtained due to the formation of hydrogen bonds between GO and PVP.

  9. CTP:phosphocholine cytidylyltransferase α (CCTα) and lamins alter nuclear membrane structure without affecting phosphatidylcholine synthesis.

    PubMed

    Gehrig, Karsten; Ridgway, Neale D

    2011-06-01

    CTP:phosphocholine cytidylyltransferase α (CCTα) is a nuclear enzyme that catalyzes the rate-limiting step in the CDP-choline pathway for phosphatidylcholine (PC) synthesis. Lipid activation of CCTα results in its translocation to the nuclear envelope and expansion of an intranuclear membrane network termed the nucleoplasmic reticulum (NR) by a mechanism involving membrane deformation. Nuclear lamins are also required for stability and proliferation of the NR, but whether this unique structure, or the nuclear lamina in general, is required for PC synthesis is not known. To examine this relationship, the nuclear lamina was depleted by RNAi or disrupted by expression of the Hutchinson-Gilford progeria syndrome (HGPS) mutant lamin A (progerin), and the effect on CCTα and choline metabolism was analyzed. siRNA-mediated silencing of lamin A/C or lamin B1 in CHO cells to diminish the NR had no effect on PC synthesis, while double knockdown non-specifically inhibited the pathway. Confirming this minor role in PC synthesis, only 10% of transiently overexpressed choline/ethanolamine phosphotransferase was detected in the NR. In CHO cells, CCTα was nucleoplasmic and co-localized with GFP-progerin in nuclear folds and invaginations; however, HGPS fibroblasts displayed an abnormal distribution of CCTα in the cytoplasm and nuclear envelope that was accompanied by a 2-fold reduction in PC synthesis. In spite of its altered localization, choline-labeling experiments showed that CCT activity was unaffected, and inhibition of PC synthesis was traced to reduced activity of a hemicholinium-sensitive choline transporter. We conclude that CCTα and lamins specifically cooperate to form the NR, but the overall structure of the nuclear envelope has a minimal impact on CCT activity and PC synthesis.

  10. Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M.; Elzatahry, Ahmed A.; Zheng, Gengfeng

    2015-08-01

    capacitances at current densities from 1 to 20 A g-1, with excellent capacitance retention (>90%) at 10 A g-1 for over 10 000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm-2 at 1.65 V vs. the RHE. Electronic supplementary information (ESI) available: Supporting figures, with additional SEM images, EDS spectra, N2 sorption isotherms, charge-discharge curves, cycling performance, Ragone plot, Nyquist plots and linear scan voltammogram plots. See DOI: 10.1039/c5nr04603c

  11. Enhanced treatment performance of coking wastewater and reduced membrane fouling using a novel EMBR.

    PubMed

    Jiang, Bei; Du, Cong; Shi, Shengnan; Tan, Liang; Li, Meidi; Liu, Jiaxin; Xue, Lanlan; Ji, Xiangyu

    2017-04-01

    A novel EMBR (electric field applied in MBR) by placing stainless steel mesh cathode inside a flat membrane module and stainless steel mesh anode outside the module was built and operated to enhance the treatment performance of coking wastewater containing phenol, pyridine and quinoline and reduce the membrane fouling. The degradation rates of COD, phenol, pyridine and quinoline in EMBR with electric field (reactor A) were significantly higher than the sum of EMBR without electric field (reactor B) and only electro-catalytic degradation during the long-term treatment, confirming that a coupling effect was existed between biodegradation and electro-catalytic degradation process. Illumina sequencing data revealed that bacterial community was richer and more diverse in reactor A. Comamonas strain JB as the inoculums was the most dominant genus in each reactor and electric field applied in reactor A further improved the abundance of strain JB. The membrane fouling in reactor A was reduced.

  12. Performance evaluation of attached growth membrane bioreactor for treating polluted surface water.

    PubMed

    Li, Lu; Suwanate, Siwaporn; Visvanathan, C

    2017-01-25

    Attached growth membrane bioreactor (aMBR) process was investigated for treating polluted surface water with CODMn around 10mg/L of raw water. Lab scale reactors, aMBR with 15% PVA-gel as carrier and conventional membrane filtration reactor (MF) were tested in parallel. aMBR achieved two times higher CODMn removal than MF system. Ammonia removal occurred almost completely in both MF and aMBR system - around 94% and 96%, respectively. Permeate turbidity was almost totally removed while UV254 removal was around 15% in MF and 20% in aMBR system. aMBR system largely mitigated membrane fouling and prolonged the system operation time. Results showed 2h hydraulic retention time provided relatively higher removal efficiency and stable operation performance. Modified Stover Kincannon model was able to match the aMBR system.

  13. Effect of surfactants and temperature on the hyperfiltration performance of poly(ether/urea) membranes

    NASA Technical Reports Server (NTRS)

    Leban, M. I.; Wydeven, T. J.

    1984-01-01

    The individual and combined effects of pasteurization temperature (347 K) and surfactants (anionic, cationic, and neutral) on a poly(ether/urea) thin-film hyperfiltration membrane were studied. Performance of this positively charged membrane was measured in terms of sodium chloride rejection and water flux. The observed effect was mostly on water flux and minimal on salt rejection. Pasteurization temperature caused an irreversible flux decline (flux decline slope of 0.09). The gradual flux reduction caused by neutral and cationic surfactants was reversible, whereas the flux reduction caused by anionic surfactant was irreversible and of similar magnitude to flux reduction caused by pasteurization temperature. The effects of anionic surfactant and pasteurization temperature were additive. Because of flux decline at elevated temperatures the poly(ether/urea) membrane is not very attractive for long-term spaceflight use.

  14. Reverse osmosis membrane composition, structure and performance modification by bisulphite, iron(III), bromide and chlorite exposure.

    PubMed

    Ferrer, O; Gibert, O; Cortina, J L

    2016-10-15

    Reverse osmosis (RO) membrane exposure to bisulphite, chlorite, bromide and iron(III) was assessed in terms of membrane composition, structure and performance. Membrane composition was determined by Rutherford backscattering spectrometry (RBS) and membrane performance was assessed by water and chloride permeation, using a modified version of the solution-diffusion model. Iron(III) dosage in presence of bisulphite led to an autooxidation of the latter, probably generating free radicals which damaged the membrane. It comprised a significant raise in chloride passage (chloride permeation coefficient increased 5.3-5.1 fold compared to the virgin membrane under the conditions studied) rapidly. No major differences in terms of water permeability and membrane composition were observed. Nevertheless, an increase in the size of the network pores, and a raise in the fraction of aggregate pores of the polyamide (PA) layer were identified, but no amide bond cleavage was observed. These structural changes were therefore, in accordance with the transport properties observed.

  15. Characterization and Evaluation of Reverse Osmosis Membranes Modified with Ag2O Nanoparticles to Improve Performance.

    PubMed

    Al-Hobaib, Abdullah S; Al-Sheetan, Khalid M; Shaik, Mohammed Rafi; Al-Andis, Naser M; Al-Suhybani, M S

    2015-12-01

    The objective of this work was to prepare and characterize a new and highly efficient modified membrane by in situ interfacial polymerization on porous polysulfone supports. The process used m-phenylenediamine and trimesoyl chloride in hexane, incorporating silver oxide Ag2O nanoparticles of varied concentrations from 0.001 to 0.1 wt%. Ag2O nanoparticles were prepared at different sizes varying between 20 and 50 nm. The modified membranes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), transmission electron microscopy (TEM), and contact angle measurement. The results showed a smooth membrane surface and average surface roughness from 31 to 74 nm. Moreover, hydrophilicity improved and the contact angle decreased to 41° at 0.009 wt% silver oxide. The performances of the developed membranes were investigated by measuring permeate fluxes and salt rejection capability by passing NaCl solutions (2000 ppm) through the membranes at 225 psi. The results showed that the flux increased from 26 to 40.5 L/m(2) h, while the salt rejection was high, at 99 %, with 0.003 wt% Ag2O nanoparticles.

  16. Pervaporation performance of PPO membranes in dehydration of highly hazardous mmh and udmh liquid propellants.

    PubMed

    Moulik, Siddhartha; Kumar, K Praveen; Bohra, Subha; Sridhar, Sundergopal

    2015-05-15

    Polyphenylene oxide (PPO) membranes synthesized from 2,6-dimethyl phenol monomer were subjected to pervaporation-based dehydration of the highly hazardous and hypergolic monomethyl hydrazine (MMH) and unsymmetrical dimethyl hydrazine (UDMH) liquid propellants. Membranes were characterized by TGA, DSC and SEM to study the effect of temperature besides morphologies of surface and cross-section of the films, respectively. Molecular dynamics (MD) simulation was used to study the diffusion behavior of solutions within the membrane. CFD method was employed to solve the governing mass transfer equations by considering the flux coupling. The modeling results were highlighted by the experimental data and were in good agreement. High separation factors (35-70) and reasonable water fluxes (0.1-0.2 kg/m(2)h) were observed for separation of the aqueous azeotropes of MMH (35 wt%) and UDMH (20 wt%) and their further enrichment to >90% purity. Effect of feed composition, membrane thickness and permeate pressure on separation performance of PPO membranes were investigated to determine optimum operating conditions.

  17. Performance assessment of a pilot-size vacuum rotation membrane bioreactor treating urban wastewater

    NASA Astrophysics Data System (ADS)

    Alnaizy, Raafat; Aidan, Ahmad; Luo, Haonan

    2011-12-01

    This study investigated the suitability and performance of a pilot-scale membrane bioreactor (MBR). Huber vacuum rotation membrane (VRM 20/36) bioreactor was installed at the Sharjah sewage treatment plant (STP) in the United Arab Emirate for 12 months. The submerged membranes were flat sheets with a pore size of 0.038 μm. The VRM bioreactor provided a final effluent of very high quality. The average reduction on parameters such as COD was from 620 to 3 mg/l, BOD from 239 to 3 mg/l, Ammonia from 37 to 2 mg/l, turbidity from 225NTU to less than 3NTU, and total suspended solids from 304 mg/l to virtually no suspended solids. The rotating mechanism of the membrane panels permitted the entire membrane surface to receive the same intensive degree of air scouring, which lead to a longer duration. The MBR process holds a promising future because of its smaller footprints in contrast to conventional systems, superior effluent quality, and high loading rate capacity.

  18. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

    NASA Astrophysics Data System (ADS)

    Reis, Rackel; Dumée, Ludovic F.; Tardy, Blaise L.; Dagastine, Raymond; Orbell, John D.; Schutz, Jürg A.; Duke, Mikel C.

    2016-07-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

  19. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification.

    PubMed

    Reis, Rackel; Dumée, Ludovic F; Tardy, Blaise L; Dagastine, Raymond; Orbell, John D; Schutz, Jürg A; Duke, Mikel C

    2016-07-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

  20. Tunable High Performance Cross-Linked Alkaline Anion Exchange Membranes for Fuel Cell Applications

    SciTech Connect

    Robertson, Nicholas J.; Kostalik, IV, Henry A.; Clark, Timothy J.; Mutolo, Paul F.; Abruña, Héctor D.; Coates, Geoffrey W.

    2010-02-23

    Fuel cells are energy conversion devices that show great potential in numerous applications ranging from automobiles to portable electronics. However, further development of fuel cell components is necessary for them to become commercially viable. One component critical to their performance is the polymer electrolyte membrane, which is an ion conductive medium separating the two electrodes. While proton conducting membranes are well established (e.g., Nafion), hydroxide conducting membranes (alkaline anion exchange membranes, AAEMs) have been relatively unexplored by comparison. Operating under alkaline conditions offers significant efficiency benefits, especially for the oxygen reduction reaction; therefore, effective AAEMs could significantly advance fuel cell technologies. Here we demonstrate the use of ring-opening metathesis polymerization to generate new cross-linked membrane materials exhibiting high hydroxide ion conductivity and good mechanical properties. Cross-linking allows for increased ion incorporation, which, in turn supports high conductivities. This facile synthetic approach enables the preparation of cross-linked materials with the potential to meet the demands of hydrogen-powered fuel cells as well as direct methanol fuel cells.

  1. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

    PubMed Central

    Reis, Rackel; Dumée, Ludovic F.; Tardy, Blaise L.; Dagastine, Raymond; Orbell, John D.; Schutz, Jürg A.; Duke, Mikel C.

    2016-01-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties. PMID:27363670

  2. Performance of single chamber biocatalyzed electrolysis with different types of ion exchange membranes.

    PubMed

    Rozendal, René A; Hamelers, Hubertus V M; Molenkamp, Redmar J; Buisman, Cees J N

    2007-05-01

    In this paper hydrogen production through biocatalyzed electrolysis was studied for the first time in a single chamber configuration. Single chamber biocatalyzed electrolysis was tested in two configurations: (i) with a cation exchange membrane (CEM) and (ii) with an anion exchange membrane (AEM). Both configurations performed comparably and produced over 0.3 m3 H2/m3 reactor liquid volume/day at 1.0 V applied voltage (overall hydrogen efficiencies around 23%). Analysis of the water that permeated through the membrane revealed that a large part of potential losses in the system were associated with a pH gradient across the membrane (CEM DeltapH=6.4; AEM DeltapH=4.4). These pH gradient associated potential losses were lower in the AEM configuration (CEM 0.38 V; AEM 0.26 V) as a result of its alternative ion transport properties. This benefit of the AEM, however, was counteracted by the higher cathode overpotentials occurring in the AEM configuration (CEM 0.12 V at 2.39 A/m2; AEM 0.27 V at 2.15 A/m2) as a result of a less effective electroless plating method for the AEM membrane electrode assembly (MEA).

  3. The biocompatibility and separation performance of antioxidative polysulfone/vitamin E TPGS composite hollow fiber membranes.

    PubMed

    Dahe, Ganpat J; Teotia, Rohit S; Kadam, Sachin S; Bellare, Jayesh R

    2011-01-01

    The extended interaction of blood with certain materials like hemodialysis membranes results in the activation of cellular element as well as inflammatory response. This results in hypersensitive reactions and increased reactive oxygen species, which occurs during or immediately after dialysis. Although polysulfone (Psf) hollow fiber has been commercially used for acute and chronic hemodialysis, its biocompatibility remains a major concern. To overcome this, we have successfully made composite Psf hollow fiber membrane consisting of hydrophilic/hydrophobic micro-domains of Psf and Vitamin E TPGS (TPGS). These were prepared by dry-wet spinning using 5, 10, 15, 20 wt% TPGS as an additive in dope solution. TPGS was successfully entrapped in Psf hollow fiber, as confirmed by ATR-FTIR and TGA. The selective skin was formed at inner side of hollow fibers, as confirmed by SEM study. In vitro biocompatibility and performance of the Psf/TPGS composite membranes were examined, with cytotoxicity, ROS generation, hemolysis, platelet adhesion, contact and complement activation, protein adsorption, ultrafiltration coefficient, solute rejection and urea clearance. We show that antioxidative composite Psf exhibits enhanced biocompatibility, and the membranes show high flux and high urea clearance, about two orders of magnitude better than commercial hemodialysis membranes on a unit area basis.

  4. A review on the performance and modelling of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Boucetta, A.; Ghodbane, H.; Ayad, M. Y.; Bahri, M.

    2016-07-01

    Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flows and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.

  5. Affective Responses to an Aerobic Dance Class: The Impact of Perceived Performance.

    ERIC Educational Resources Information Center

    Bartholomew, John B.; Miller, Bridget M.

    2002-01-01

    Tested the mastery hypothesis as an explanation for the affective benefits of acute exercise. Undergraduate women from a self-selected aerobic dance class rated their exercise performance following class. Affect questionnaires were completed before and at 5 and 20 minutes after the class. Results showed an overall improvement in affect following…

  6. The membrane-extrinsic domain of cytochrome b(558/566) from the archaeon Sulfolobus acidocaldarius performs pivoting movements with respect to the membrane surface.

    PubMed

    Schoepp-Cothenet, B; Schütz, M; Baymann, F; Brugna, M; Nitschke, W; Myllykallio, H; Schmidt, C

    2001-01-05

    The orientation of the membrane-attached cytochrome b(558/566)-haem with respect to the membrane was determined by electron paramagnetic resonance spectroscopy on two-dimensionally ordered oxidised membrane fragments from Sulfolobus acidocaldarius. Unlike the other redox centres in the membrane, the cytochrome b(558/566)-haem was found to cover a range of orientations between 25 degrees and 90 degrees. The described results are reminiscent of those obtained on the Rieske cluster of bc complexes and indicate that the membrane-extrinsic domain of cytochrome b(558/566) can perform pivoting motion between two extreme positions. Such a conformational flexibility is likely to play a role in electron transfer with its redox partners.

  7. Oncogenic Mutations Differentially Affect Bax Monomer, Dimer, and Oligomeric Pore Formation in the Membrane

    NASA Astrophysics Data System (ADS)

    Zhang, Mingzhen; Zheng, Jie; Nussinov, Ruth; Ma, Buyong

    2016-09-01

    Dysfunction of Bax, a pro-apoptotic regulator of cellular metabolism is implicated in neurodegenerative diseases and cancer. We have constructed the first atomistic models of the Bax oligomeric pore consisting with experimental residue-residue distances. The models are stable, capturing well double electron-electron resonance (DEER) spectroscopy measurements and provide structural details in line with the DEER data. Comparison with the latest experimental results revealed that our models agree well with both Bax and Bak pores, pointed to a converged structural arrangement for Bax and Bak pore formation. Using multi-scale molecular dynamics simulations, we probed mutational effects on Bax transformation from monomer → dimer → membrane pore formation at atomic resolution. We observe that two cancer-related mutations, G40E and S118I, allosterically destabilize the monomer and stabilize an off-pathway swapped dimer, preventing productive pore formation. This observation suggests a mechanism whereby the mutations may work mainly by over-stabilizing the monomer → dimer transformation toward an unproductive off-pathway swapped-dimer state. Our observations point to misfolded Bax states, shedding light on the molecular mechanism of Bax mutation-elicited cancer. Most importantly, the structure of the Bax pore facilitates future study of releases cytochrome C in atomic detail.

  8. Membrane stretch affects gating modes of a skeletal muscle sodium channel.

    PubMed Central

    Tabarean, I V; Juranka, P; Morris, C E

    1999-01-01

    The alpha subunit of the human skeletal muscle Na(+) channel recorded from cell-attached patches yielded, as expected for Xenopus oocytes, two current components that were stable for tens of minutes during 0.2 Hz stimulation. Within seconds of applying sustained stretch, however, the slower component began decreasing and, depending on stretch intensity, disappeared in 1-3 min. Simultaneously, the faster current increased. The resulting fast current kinetics and voltage sensitivity were indistinguishable from the fast components 1) left after 10 Hz depolarizations, and 2) that dominated when alpha subunit was co-expressed with human beta1 subunit. Although high frequency depolarization-induced loss of slow current was reversible, the stretch-induced slow-to-fast conversion was irreversible. The conclusion that stretch converted a single population of alpha subunits from an abnormal slow to a bona fide fast gating mode was confirmed by using gigaohm seals formed without suction, in which fast gating was originally absent. For brain Na(+) channels, co-expressing G proteins with the channel alpha subunit yields slow gating. Because both stretch and beta1 subunits induced the fast gating mode, perhaps they do so by minimizing alpha subunit interactions with G proteins or with other regulatory molecules available in oocyte membrane. Because of the possible involvement of oocyte molecules, it remains to be determined whether the Na(+) channel alpha subunit was directly or secondarily susceptible to bilayer tension. PMID:10423424

  9. Oncogenic Mutations Differentially Affect Bax Monomer, Dimer, and Oligomeric Pore Formation in the Membrane

    PubMed Central

    Zhang, Mingzhen; Zheng, Jie; Nussinov, Ruth; Ma, Buyong

    2016-01-01

    Dysfunction of Bax, a pro-apoptotic regulator of cellular metabolism is implicated in neurodegenerative diseases and cancer. We have constructed the first atomistic models of the Bax oligomeric pore consisting with experimental residue-residue distances. The models are stable, capturing well double electron-electron resonance (DEER) spectroscopy measurements and provide structural details in line with the DEER data. Comparison with the latest experimental results revealed that our models agree well with both Bax and Bak pores, pointed to a converged structural arrangement for Bax and Bak pore formation. Using multi-scale molecular dynamics simulations, we probed mutational effects on Bax transformation from monomer → dimer → membrane pore formation at atomic resolution. We observe that two cancer-related mutations, G40E and S118I, allosterically destabilize the monomer and stabilize an off-pathway swapped dimer, preventing productive pore formation. This observation suggests a mechanism whereby the mutations may work mainly by over-stabilizing the monomer → dimer transformation toward an unproductive off-pathway swapped-dimer state. Our observations point to misfolded Bax states, shedding light on the molecular mechanism of Bax mutation-elicited cancer. Most importantly, the structure of the Bax pore facilitates future study of releases cytochrome C in atomic detail. PMID:27630059

  10. Students' Achievement Goals, Emotion Perception Ability and Affect and Performance in the Classroom: A Multilevel Examination

    ERIC Educational Resources Information Center

    Vassiou, Aikaterini; Mouratidis, Athanasios; Andreou, Eleni; Kafetsios, Konstantinos

    2016-01-01

    Performance at school is affected not only by students' achievement goals but also by emotional exchanges among classmates and their teacher. In this study, we investigated relationships between students' achievement goals and emotion perception ability and class affect and performance. Participants were 949 Greek adolescent students in 49 classes…

  11. 40 CFR Table 3 to Subpart Nnnnn of... - Performance Test Requirements for HCl Production Affected Sources

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 14 2011-07-01 2011-07-01 false Performance Test Requirements for HCl... Requirements for HCl Production Affected Sources As stated in § 63.9020, you must comply with the following requirements for performance tests for HCl production for each affected source. For each HCl process vent...

  12. High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode

    NASA Astrophysics Data System (ADS)

    Kim, Sang Moon; Ahn, Chi-Yeong; Cho, Yong-Hun; Kim, Sungjun; Hwang, Wonchan; Jang, Segeun; Shin, Sungsoo; Lee, Gunhee; Sung, Yung-Eun; Choi, Mansoo

    2016-05-01

    We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance.

  13. High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode

    PubMed Central

    Kim, Sang Moon; Ahn, Chi-Yeong; Cho, Yong-Hun; Kim, Sungjun; Hwang, Wonchan; Jang, Segeun; Shin, Sungsoo; Lee, Gunhee; Sung, Yung-Eun; Choi, Mansoo

    2016-01-01

    We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance. PMID:27210793

  14. Improving dynamic performance of proton-exchange membrane fuel cell system using time delay control

    NASA Astrophysics Data System (ADS)

    Kim, Young-Bae

    Transient behaviour is a key parameter for the vehicular application of proton-exchange membrane (PEM) fuel cell. The goal of this presentation is to construct better control technology to increase the dynamic performance of a PEM fuel cell. The PEM fuel cell model comprises a compressor, an injection pump, a humidifier, a cooler, inlet and outlet manifolds, and a membrane-electrode assembly. The model includes the dynamic states of current, voltage, relative humidity, stoichiometry of air and hydrogen, cathode and anode pressures, cathode and anode mass flow rates, and power. Anode recirculation is also included with the injection pump, as well as anode purging, for preventing anode flooding. A steady-state, isothermal analytical fuel cell model is constructed to analyze the mass transfer and water transportation in the membrane. In order to prevent the starvation of air and flooding in a PEM fuel cell, time delay control is suggested to regulate the optimum stoichiometry of oxygen and hydrogen, even when there are dynamical fluctuations of the required PEM fuel cell power. To prove the dynamical performance improvement of the present method, feed-forward control and Linear Quadratic Gaussian (LQG) control with a state estimator are compared. Matlab/Simulink simulation is performed to validate the proposed methodology to increase the dynamic performance of a PEM fuel cell system.

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

    PubMed

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

    2017-02-01

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

  16. Influence of photo-induced superhydrophilicity of titanium dioxide nanoparticles on the anti-fouling performance of ultrafiltration membranes

    NASA Astrophysics Data System (ADS)

    Madaeni, S. S.; Ghaemi, N.; Alizadeh, A.; Joshaghani, M.

    2011-05-01

    Fouling is one of the most present prominent problems in almost all membrane processes. An increase in the membrane hydrophilicity is one of the effective ways to improve the membrane resistance to fouling. In this research, TiO 2 nanoparticles were deposited on the surface of composite ultrafiltration (UF) membrane, and then irradiated by ultraviolet (UV) light. The coating of the membrane surface with TiO 2 nanoparticles and radiation with (UV) light led to the considerable increase of hydrophilicity on the membrane surface. The deposition of TiO 2 nanoparticles was carried out through coordinance bonds with OH functional groups of the polymer on the membrane surface. The flux through a coated and (UV) light radiated membrane was increased to a large extent compared to a virgin membrane. In this research, the effect of different concentrations of TiO 2 nanoparticles in the presence and absence of (UV) irradiation was investigated, and the role of increasing of hydrophilicity on the anti-fouling property of membranes was studied. In order to characterize the membranes FTIR, XRD, SEM, water contact angle and cross-flow filtration were employed. This procedure is a useful technique for improvement of hydrophilicity to decrease (increase) fouling (anti-fouling performance) and enhance the permeation of membranes.

  17. Comparative studies on performance of radiation-induced and thermal cross-linked ion-exchange membrane for water electrolysis

    NASA Astrophysics Data System (ADS)

    Chakrabarty, Tina; Jasti, Amaranadh; Goel, N. K.; Shahi, Vinod K.; Sabharwal, Sunil

    2011-07-01

    Radiation-induced and thermal cross-linked sulfonated poly(ether sulfone) (SPS)-sulfonated poly(ether ether ketone) (SPK) composite ion-exchange membranes (SPS/SPK(γ) and SPS/SPK(T), respectively) were prepared. Their performances for water electrolysis were comparatively assessed. Thermal cross-linked membrane (SPS/SPK(T)) showed cross-linking of part functional groups (-SO 3H) and thus deterioration in membrane conductivity. While, radiation-induced cross-linked membrane (SPS/SPK(γ)) avoided any cross-linking between functional groups and thus conductivity. Electrolysis performances of these membranes were evaluated in comparison with Nafion117 membrane. Relatively low current efficiency (CE) for SPS/SPK and SPS/SPK(T) membranes was due to their high mass transfer (water) via electro-osmotic drag, which was negligible for SPS/SPK(γ) membrane. SPS/SPK(γ) membrane exhibited comparable stabilities and water splitting performance with Nafion117 membrane, which revealed its suitability as substitute for electrochemical applications.

  18. Identifying Affective Domains That Correlate and Predict Mathematics Performance in High-Performing Students in Singapore

    ERIC Educational Resources Information Center

    Lim, Siew Yee; Chapman, Elaine

    2015-01-01

    Past studies have shown that distinct yet highly correlated sub-constructs of three broad mathematics affective variables: (a) motivation, (b) attitudes and (c) anxiety, have varying degree of correlation with mathematics achievement. The sub-constructs of these three affective constructs are as follows: (a) (i) amotivation, (ii) external…

  19. Psoralen and Ultraviolet A Light Treatment Directly Affects Phosphatidylinositol 3-Kinase Signal Transduction by Altering Plasma Membrane Packing.

    PubMed

    Van Aelst, Britt; Devloo, Rosalie; Zachée, Pierre; t'Kindt, Ruben; Sandra, Koen; Vandekerckhove, Philippe; Compernolle, Veerle; Feys, Hendrik B

    2016-11-18

    Psoralen and ultraviolet A light (PUVA) are used to kill pathogens in blood products and as a treatment of aberrant cell proliferation in dermatitis, cutaneous T-cell lymphoma, and graft-versus-host disease. DNA damage is well described, but the direct effects of PUVA on cell signal transduction are poorly understood. Because platelets are anucleate and contain archetypal signal transduction machinery, they are ideally suited to address this. Lipidomics on platelet membrane extracts showed that psoralen forms adducts with unsaturated carbon bonds of fatty acyls in all major phospholipid classes after PUVA. Such adducts increased lipid packing as measured by a blue shift of an environment-sensitive fluorescent probe in model liposomes. Furthermore, the interaction of these liposomes with lipid order-sensitive proteins like amphipathic lipid-packing sensor and α-synuclein was inhibited by PUVA. In platelets, PUVA caused poor membrane binding of Akt and Bruton's tyrosine kinase effectors following activation of the collagen glycoprotein VI and thrombin protease-activated receptor (PAR) 1. This resulted in defective Akt phosphorylation despite unaltered phosphatidylinositol 3,4,5-trisphosphate levels. Downstream integrin activation was furthermore affected similarly by PUVA following PAR1 (effective half-maximal concentration (EC50), 8.4 ± 1.1 versus 4.3 ± 1.1 μm) and glycoprotein VI (EC50, 1.61 ± 0.85 versus 0.26 ± 0.21 μg/ml) but not PAR4 (EC50, 50 ± 1 versus 58 ± 1 μm) signal transduction. Our findings were confirmed in T-cells from graft-versus-host disease patients treated with extracorporeal photopheresis, a form of systemic PUVA. In conclusion, PUVA increases the order of lipid phases by covalent modification of phospholipids, thereby inhibiting membrane recruitment of effector kinases.

  20. Influence of chemical microstructure of single-ion polymeric electrolyte membranes on performance of lithium-ion batteries.

    PubMed

    Zhang, Yunfeng; Rohan, Rupesh; Cai, Weiwei; Xu, Guodong; Sun, Yubao; Lin, An; Cheng, Hansong

    2014-10-22

    A novel protocol to generate and control porosity in polymeric structures is presented for fabrication of single ion polymer electrolyte (SIPE) membranes for lithium ion batteries. A series of SIPEs with varying ratios of aliphatic and aromatic segments was successfully synthesized and subsequently blended with PVDF-HFP to fabricate membranes of various sizes of pores. The membranes were characterized using techniques including SEM, solvent uptake capacity measurement and ionic conductivity. We demonstrate that appropriate membrane porosity enhances ionic conductivity, reduces interfacial resistance between electrodes and electrolyte and ultimately boosts performance of Li-ion batteries. The implication of the structure-performance relationship for battery design is discussed.

  1. Performance equations for a polymer electrolyte membrane fuel cell with unsaturated cathode feed

    NASA Astrophysics Data System (ADS)

    Hsuen, Hsiao-Kuo; Yin, Ken-Ming

    A mathematical formulation for the cathode of a membrane electrode assembly of a polymer electrolyte membrane fuel cell is proposed, in which the effect of unsaturated vapor feed in the cathode is considered. This mechanistic model formulates the water saturation front within the gas diffusion layer with an explicit analytical expression as a function of operating conditions. The multi-phase flows of gaseous species and liquid water are correlated with the established capillary pressure equilibrium in the medium. In addition, less than fully hydrated water contents in the polymer electrolyte and catalyst layers are considered, and are integrated with the relevant liquid and vapor transfers in the gas diffusion layer. The developed performance equations take into account the influences of all pertinent material properties on cell performance using first principles. The mathematical approach is logical and concise in terms of revealing the underlying physical significance in comparison with many other empirical data fitting models.

  2. High-performance Polymer Membranes with Multi-functional Amphiphilic Micelles for CO2 Capture.

    PubMed

    Kim, Sang Jin; Jeon, Harim; Kim, Dong Jun; Kim, Jong Hak

    2015-11-01

    Herein, we report a high performance polymer membrane with simultaneously large improvements in the CO2 permeability and CO2/N2 selectivity. These improvements are obtained by incorporation of a multi-functional amphiphilic comb copolymer micelle, that is, poly(dimethylsiloxane)-g-poly(oxyethylene methacrylate) (PDMS-g-POEM), into a poly(amide-b-ethylene oxide) (Pebax) matrix. Both CO2 and N2 permeabilities continuously increased with PDMS-g-POEM content, whereas the CO2/N2 selectivity increased up to 40 wt % of PDMS-g-POEM, which enabled the maximum performance to approach the upper bound limit (2008). The membranes with PDMS-g-POEM exhibited greater CO2 permeability and CO2/N2 selectivity than those with a zeolitic imidazolate framework (ZIF-8), a well-known expensive inorganic filler, indicating the effectiveness of PDMS-g-POEM micelles for CO2 capture.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-03-18

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

  6. Enteric YaiW Is a Surface-Exposed Outer Membrane Lipoprotein That Affects Sensitivity to an Antimicrobial Peptide

    PubMed Central

    Arnold, Markus F. F.; Caro-Hernandez, Paola; Tan, Karen; Runti, Giulia; Wehmeier, Silvia; Scocchi, Marco; Doerrler, William T.; Ferguson, Gail P.

    2014-01-01

    yaiW is a previously uncharacterized gene found in enteric bacteria that is of particular interest because it is located adjacent to the sbmA gene, whose bacA ortholog is required for Sinorhizobium meliloti symbiosis and Brucella abortus pathogenesis. We show that yaiW is cotranscribed with sbmA in Escherichia coli and Salmonella enterica serovar Typhi and Typhimurium strains. We present evidence that the YaiW is a palmitate-modified surface exposed outer membrane lipoprotein. Since BacA function affects the very-long-chain fatty acid (VLCFA) modification of S. meliloti and B. abortus lipid A, we tested whether SbmA function might affect either the fatty acid modification of the YaiW lipoprotein or the fatty acid modification of enteric lipid A but found that it did not. Interestingly, we did observe that E. coli SbmA suppresses deficiencies in the VLCFA modification of the lipopolysaccharide of an S. meliloti bacA mutant despite the absence of VLCFA in E. coli. Finally, we found that both YaiW and SbmA positively affect the uptake of proline-rich Bac7 peptides, suggesting a possible connection between their cellular functions. PMID:24214946

  7. Identification of key water quality characteristics affecting the filterability of biologically treated effluent in low-pressure membrane filtration.

    PubMed

    Nguyen, T; Fan, L; Roddick, F A; Harris, J L

    2010-01-01

    There are many water quality characteristics which could influence the filterability of biologically treated effluent from Melbourne's Western Treatment Plant (WTP). Statistical correlation was used to identify the key water characteristics affecting the microfiltration (MF) and ultrafiltration (UF) filterability in terms of permeate volume of the treated effluent. The models developed showed that turbidity, dissolved organic carbon (DOC) and total suspended solids (TSS) were the key factors which influenced the MF and UF filterability. Turbidity was the dominant factor affecting the accuracy of the model for MF filterability while DOC was the major factor affecting the accuracy of the model for UF filterability. A prediction accuracy of 85% was obtained for MF and 86% for UF filterability of the WTP effluent. The characteristics of the organic components of the wastewater were demonstrated by EEM spectra to have seasonal variation which would have reduced the prediction accuracy. As turbidity, DOC and TSS can be determined on-line, the models would be useful for rapid prediction of the filterability of WTP effluent and this may assist the control of low-pressure membrane filtration processes.

  8. Combined effects of positive and negative affectivity and job satisfaction on job performance and turnover intentions.

    PubMed

    Bouckenooghe, Dave; Raja, Usman; Butt, Arif Nazir

    2013-01-01

    Capturing data from employee-supervisor dyads (N = 321) from eight organizations in Pakistan, including human service organizations, an electronics assembly plant, a packaging material manufacturing company, and a small food processing plant, we used moderated regression analysis to examine whether the relationships between trait affect (positive affectivity [PA] and negative affectivity [NA]) and two key work outcome variables (job performance and turnover) are contingent upon the level of job satisfaction. We applied the Trait Activation Theory to explain the moderating effect of job satisfaction on the relationship between affect and performance and between affect and turnover. Overall, the data supported our hypotheses. Positive and negative affectivity influenced performance and the intention to quit, and job satisfaction moderated these relationships. We discuss in detail the results of these findings and their implications for research and practice.

  9. Chemical properties of lipids strongly affect the kinetics of the membrane-induced aggregation of α-synuclein

    PubMed Central

    Brown, James W. P.; Ouberai, Myriam M.; Flagmeier, Patrick; Vendruscolo, Michele; Buell, Alexander K.; Sparr, Emma; Dobson, Christopher M.

    2016-01-01

    Intracellular α-synuclein deposits, known as Lewy bodies, have been linked to a range of neurodegenerative disorders, including Parkinson’s disease. α-Synuclein binds to synthetic and biological lipids, and this interaction has been shown to play a crucial role for both α-synuclein’s native function, including synaptic plasticity, and the initiation of its aggregation. Here, we describe the interplay between the lipid properties and the lipid binding and aggregation propensity of α-synuclein. In particular, we have observed that the binding of α-synuclein to model membranes is much stronger when the latter is in the fluid rather than the gel phase, and that this binding induces a segregation of the lipids into protein-poor and protein-rich populations. In addition, α-synuclein was found to aggregate at detectable rates only when interacting with membranes composed of the most soluble lipids investigated here. Overall, our results show that the chemical properties of lipids determine whether or not the lipids can trigger the aggregation of α-synuclein, thus affecting the balance between functional and aberrant behavior of the protein. PMID:27298346

  10. Effects of membrane molecular weight cutoff on performance of a novel bioartificial liver.

    PubMed

    Shi, Xiao-lei; Zhang, Yue; Han, Bing; Gu, Jin-yang; Chu, Xue-hui; Xiao, Jiang-qiang; Ren, Hao-zhen; Tan, Jiao-jun; Ding, Yi-tao

    2011-03-01

    Immunoisolation using semipermeable membranes has been incorporated into bioartificial liver (BAL) devices to separate cellular components of the recipient's immune system from the cells within the BAL device. This study was designed to explore the influence of membrane molecular weight cutoff on performance of the multilayer radial-flow BAL using porcine hepatocytes cocultured with mesenchymal stem cells. In this study, healthy beagles underwent 6-h treatment with a BAL containing membrane with 200 kDa retention rating or 1200 kDa retention rating. Functional markers of BAL performance were monitored before and after treatment, as well as cytotoxic immune response to BAL therapy. The results showed that hepatocyte performance levels such as albumin secretion, urea synthesis, and viability were all significantly higher in 200 kDa retention rating group compared with the 1200 kDa retention rating group after treatment (P <  0.05). Significant levels of canine proteins were detected in BAL medium from the 1200 kDa retention rating group. Fluorescence microscopy further verified that heavy deposition of canine IgG, IgM, and complement (C3) on coculture cells was obtained after BAL treatment in the 1200 kDa retention rating group. However, only trace deposits of canine immunoproteins were observed on coculture cells obtained from BAL in the 200 kDa retention rating group. Small membrane molecular weight cutoff of the BAL could reduce the transfer of xenoreactive antibodies into the BAL medium and improve the performance of the BAL.

  11. Enhanced submerged membrane bioreactor combined with biosurfactant rhamnolipids: performance for frying oil degradation and membrane fouling reduction.

    PubMed

    Qin, Lei; Zhang, Guoliang; Meng, Qin; Zhang, Hongzi; Xu, Lusheng; Lv, Bosheng

    2012-12-01

    In this study, a novel submerged membrane bioreactor (SMBR) combined with rhamnolipids was developed to treat frying oil wastewater and control the problem of membrane fouling. To validate the feasibility of this new design, a hybrid SMBR with additional rhamnolipids (RSMBR) and a controlled SMBR (CSMBR) were run in parallel. Results demonstrated that RSMBR not only held high removal efficiency of oil up to 90% at short hydraulic time, but also exhibited 10 times higher membrane permeability in comparison to CSMBR. The presence of rhamnolipids greatly enhanced the contact and reaction between the microorganism and oil molecules. The great improvement in membrane filterability was associated with an increase in hydrophobicity of flocs as well as the increase of particle size from 53.06 to 145.54 μm. The oil strongly adhered to the surface of flocs by rhamnolipids, and consequently prevented larger oil droplets directly depositing on the membrane surface.

  12. Membrane fouling and performance evaluation of conventional membrane bioreactor (MBR), moving biofilm MBR and oxic/anoxic MBR.

    PubMed

    Khan, Sher Jamal; Ahmad, Aman; Nawaz, Muhammad Saqib; Hankins, Nicholas P

    2014-01-01

    In this study, three laboratory scale submerged membrane bioreactors (MBRs) comprising a conventional MBR (C-MBR), moving bed MBR (MB-MBR) and anoxic-oxic MBR (A/O-MBR) were continuously operated with synthesized domestic wastewater (chemical oxygen demand, COD = 500 mg/L) for 150 days under similar operational and environmental conditions. Kaldnes(®) plastic media with 20% dry volume was used as a biofilm carrier in the MB-MBR and A/O-MBR. The treatment performance and fouling propensity of the MBRs were evaluated. The effect of cake layer formation in all three MBRs was almost the same. However, pore blocking caused a major difference in the resultant water flux. The A/O-MBR showed the highest total nitrogen and phosphorus (PO4-P) removal efficiencies of 83.2 and 69.7%, respectively. Due to the high removal of nitrogen, fewer protein contents were found in the soluble and bound extracellular polymeric substances (EPS) of the A/O-MBR. Fouling trends of the MBRs showed 12, 14 and 20 days filtration cycles for C-MBR, MB-MBR and A/O-MBR, respectively. A 25% reduction of the soluble EPS and a 37% reduction of the bound EPS concentrations in A/O-MBR compared with C-MBR was a major contributing factor for fouling retardation and the enhanced filtration capacity of the A/O-MBR.

  13. A pilot-scale photocatalyst-membrane hybrid reactor: performance and characterization.

    PubMed

    Ryu, J; Choi, W; Choo, K H

    2005-01-01

    We developed and tested a pilot-scale photocatalyst-membrane hybrid reactor for water treatment. The performance of the pilot-scale reactor was evaluated by monitoring the degradation efficiency of several organic pollutants and the membrane suction pressure at different operating conditions. The concentration of humic acids rather increased in the initial period of UV illumination and then decreased gradually, which could be ascribed to the photoinduced desorption of humic acids from the TiO2 surface. The decoloring rate of methylene blue was faster than that of rhodamine B, whereas the order of mineralization rates of the dyes was reversed. 4-chlorophenol of 100 ppb was fully degraded under UV irradiation in 2 hours, which suggests that this hybrid reactor would be more suitable in removing micropollutants in water. The reactor was operated with either continuous or intermittent suction mode. In a continuous suction mode, the formation of TiO2 cake layers on the membrane surface occurred and caused a substantial increase in suction pressure. However, no further fouling (or suction pressure build-up) took place with an intermittent suction mode with the 9-min suction and 3-min pause period. The photocatalyst-membrane hybrid reactor system developed in this study could be an attractive option for controlling micropollutants in water.

  14. Design and Synthesis of Oriented Guest-Host Nanostructures for Enhanced Membrane Performances

    SciTech Connect

    Hu, M.Z.

    2005-11-15

    This project has demonstrated a novel nanomaterial design concept and a synthesis method for ''guesthost'' type superionic-conducting nanocomposite membranes. This concept consists of nanophases of oxide electrolyte nanograins (guest) encapsulated inside the nanopore channels of an oxide layer matrix (host), with channels oriented perpendicular to the layer surface. Using ionic conducting YSZ (yttrium stabilized zirconia) as a special case, we have shown that the host-guest design allows orientation of a large number channels, allowing a high density of nanograin boundaries/interfaces to be built into the film to enhance cross-membrane conductivity. This structure allowed conductivity measurements with impedance spectroscopy to be performed for the first time at room temperature. Cross-membrane conductivity values at low temperature ranges of interest are the higher than any reported values. The conductivity-enhancing mechanisms could be attributed to (1) controlled orientation and increased number density of YSZ nanograin-host interfaces and (2) creation and stabilization of YSZ nanocrystalline phases inside nanopore channels (<10 nm dia.). This successful initial demonstration of host-guest nanostructures is expected to have direct impact on fuel cell technologies, and may also have beneficial use in a broad range of applications such as in solar cells, sensors, chemical/gas separations, catalysis, and magnetic memory devices. This work may also lead to a new way to develop membrane technologies that offer orders-of-magnitude higher permeability and selectivity, as well as improved thermal stability of the desirable nanocrystalline phases.

  15. The use of nanoparticles in polymeric and ceramic membrane structures: review of manufacturing procedures and performance improvement for water treatment.

    PubMed

    Kim, Jeonghwan; Van der Bruggen, Bart

    2010-07-01

    Membrane separations are powerful tools for various applications, including wastewater treatment and the removal of contaminants from drinking water. The performance of membranes is mainly limited by material properties. Recently, successful attempts have been made to add nanoparticles or nanotubes to polymers in membrane synthesis, with particle sizes ranging from 4 nm up to 100 nm. Ceramic membranes have been fabricated with catalytic nanoparticles for synergistic effects on the membrane performance. Breakthrough effects that have been reported in the field of water and wastewater treatment include fouling mitigation, improvement of permeate quality and flux enhancement. Nanomaterials that have been used include titania, alumina, silica, silver and many others. This paper reviews the role of engineered nanomaterials in (pressure driven) membrane technology for water treatment, to be applied in drinking water production and wastewater recycling. Benefits and drawbacks are described, which should be taken into account in further studies on potential risks related to release of nanoparticles into the environment.

  16. Effect of polymer concentration on the structure and performance of PEI hollow fiber membrane contactor for CO2 stripping.

    PubMed

    Naim, R; Ismail, A F

    2013-04-15

    A series of polyetherimide (PEI) hollow fiber membranes with various polymer concentrations (13-16 wt.%) for CO2 stripping process in membrane contactor application was fabricated via wet phase inversion method. The PEI membranes were characterized in terms of liquid entry pressure, contact angle, gas permeation and morphology analysis. CO2 stripping performance was investigated via membrane contactor system in a stainless steel module with aqueous diethanolamine as liquid absorbent. The hollow fiber membranes showed decreasing patterns in gas permeation, contact angle, mean pore size and effective surface porosity with increasing polymer concentration. On the contrary, wetting pressure of PEI membranes has enhanced significantly with polymer concentration. Various polymer concentrations have different effects on the CO2 stripping flux in which membrane with 14 wt.% polymer concentration showed the highest stripping flux of 2.7 × 10(-2)mol/m(2)s. From the performance comparison with other commercial membrane, it is anticipated that the PEI membrane has a good prospect in CO2 stripping via membrane contactor.

  17. Superhydrophobic and superhydrophilic surface-enhanced separation performance of porous inorganic membranes for biomass-to-biofuel conversion applications

    DOE PAGES

    Hu, Michael Z.; Engtrakul, Chaiwat; Bischoff, Brian L.; ...

    2016-11-14

    A new class of inorganic-based membranes, i.e., High-Performance Architectured Surface Selective (HiPAS) membranes, is introduced to provide high perm-selective flux by exploiting unique separation mechanisms induced by superhydrophobic or superhydrophilic surface interactions and confined capillary condensation in enlarged membrane pores (~8 nm). The super-hydro-tunable HiPAS membranes were originally developed for the purpose of bio-oil/biofuel processing to achieve selective separations at higher flux relative to size selective porous membranes (e.g., inorganic zeolite-based membranes) and better high-temperature tolerance than polymer membranes (>250 C) for hot vapor processing. Due to surface-enhanced separation selectivity, HiPAS membranes can thus possibly enable larger pores to facilitatemore » large-flux separations by increasing from sub-nanometer pores to mesopores (2-50 nm) for vapor phase or micron-scale pores for liquid phase separations. In this paper, we describe an innovative membrane concept and a materials synthesis strategy to fabricate HiPAS membranes, and demonstrate selective permeation in both vapor- and liquid-phase applications. High permeability and selectivity were demonstrated using surrogate mixtures, such as ethanol-water, toluene-water, and toluene-phenol-water. The overall membrane evaluation results show promise for the future processing of biomass pyrolysis and upgraded product vapors and condensed liquid bio-oil intermediates.« less

  18. Development of high performance nano-porous polyethersulfone ultrafiltration membranes with hydrophilic surface and superior antifouling properties

    NASA Astrophysics Data System (ADS)

    Rahimpour, Ahmad; Madaeni, Sayed Siavash; Jahanshahi, Mohsen; Mansourpanah, Yaghoub; Mortazavian, Narmin

    2009-08-01

    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.

  19. Layer-by-Layer Fabrication of High-Performance Polyamide/ZIF-8 Nanocomposite Membrane for Nanofiltration Applications.

    PubMed

    Wang, Luying; Fang, Manquan; Liu, Jing; He, Jing; Li, Jiding; Lei, Jiandu

    2015-11-04

    The conventional blending fabrication for thin-film nanocomposite (TFN) membranes is to disperse porous fillers in aqueous/organic phases prior to interfacial polymerization, and the aggregation of fillers may lead to the significant decrease in membrane performance. To overcome this limitation, we proposed a novel layer-by-layer (LBL) fabrication to prepare a polyamide (PA)/ZIF-8 nanocomposite membrane with a multilayer structure: a porous substrate, a ZIF-8 interlayer, and a PA coating layer. The PA/ZIF-8 (LBL) membrane for nanofiltration applications was prepared by growing an interlayer of ZIF-8 nanoparticles on an ultrafiltration membrane through in situ growth and then coating it with an ultrathin PA layer through interfacial polymerization. The obtained PA/ZIF-8 (LBL) membrane exhibited both better permeance and selectivity than did the conventional PA/ZIF-8 TFN membrane because of the ZIF-8 in situ growth producing a ZIF-8 interlayer with more ZIF-8 nanoparticles but fewer aggregates. Compared with the pure PA membrane (the flux of 11.2 kg/m(2)/h and rejection of 99.6%) for dye removal, the obtained PA/ZIF-8 (LBL) membranes achieved a significant improvement in membrane permeance and selectivity. (Flux was up to 27.1 kg/m(2)/h, and the rejection reaches 99.8%.) This LBL fabrication is a promising methodology for other polymer nanocomposite membranes simultaneously having high permeance and good selectivity.

  20. Superhydrophobic and superhydrophilic surface-enhanced separation performance of porous inorganic membranes for biomass-to-biofuel conversion applications

    SciTech Connect

    Hu, Michael Z.; Engtrakul, Chaiwat; Bischoff, Brian L.; Jang, Gyoung G.; Theiss, Timothy J.; Davis, Mark F.

    2016-11-14

    A new class of inorganic-based membranes, i.e., High-Performance Architectured Surface Selective (HiPAS) membranes, is introduced to provide high perm-selective flux by exploiting unique separation mechanisms induced by superhydrophobic or superhydrophilic surface interactions and confined capillary condensation in enlarged membrane pores (~8 nm). The super-hydro-tunable HiPAS membranes were originally developed for the purpose of bio-oil/biofuel processing to achieve selective separations at higher flux relative to size selective porous membranes (e.g., inorganic zeolite-based membranes) and better high-temperature tolerance than polymer membranes (>250 C) for hot vapor processing. Due to surface-enhanced separation selectivity, HiPAS membranes can thus possibly enable larger pores to facilitate large-flux separations by increasing from sub-nanometer pores to mesopores (2-50 nm) for vapor phase or micron-scale pores for liquid phase separations. In this paper, we describe an innovative membrane concept and a materials synthesis strategy to fabricate HiPAS membranes, and demonstrate selective permeation in both vapor- and liquid-phase applications. High permeability and selectivity were demonstrated using surrogate mixtures, such as ethanol-water, toluene-water, and toluene-phenol-water. The overall membrane evaluation results show promise for the future processing of biomass pyrolysis and upgraded product vapors and condensed liquid bio-oil intermediates.

  1. Cross-linked high conductive membranes based on water soluble ionomer for high performance proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Guo, Xin; Zhang, Gang; Ni, Jing; Zhao, Chengji; Liu, Zhongguo; Zhang, Liyuan; Li, Mingyu; Xu, Shuai; Na, Hui

    2013-11-01

    In this paper, a series of proton exchange membranes prepared by “Click Reaction” are reported. The cross-linked membranes are based on water soluble sulfonated poly (ether ether ketone) containing dipropenyl groups (SDPEEK-nE/nH). Compared with self-crosslinked membranes (SDPEEK-nS), this “Click” cross-linked membranes using 1,2-Ethanedithiol and 1,6-Hexanedithiol as the cross-linker exhibit extremely reduced water uptake and swelling ratio. The lowest proton conductivity at 80 °C of the “Click” cross-linked membranes reaches to 0.168 S cm-1, and the highest methanol permeability of the “Click” cross-linked SDPEEK-8E is only 4.13 × 10-7 cm2 s-1, which is 5 times lower than that of Nafion 117 membrane. All the results imply that the cross-linked membranes with novel thiol cross-linker are promising alternative material for fuel cell application.

  2. Comparative acoustic performance and mechanical properties of silk membranes for the repair of chronic tympanic membrane perforations.

    PubMed

    Allardyce, Benjamin J; Rajkhowa, Rangam; Dilley, Rodney J; Xie, Zhigang; Campbell, Luke; Keating, Adrian; Atlas, Marcus D; von Unge, Magnus; Wang, Xungai

    2016-12-01

    The acoustic and mechanical properties of silk membranes of different thicknesses were tested to determine their suitability as a repair material for tympanic membrane perforations. Membranes of different thickness (10-100μm) were tested to determine their frequency response and their resistance to pressure loads in a simulated ear canal model. Their mechanical rigidity to pressure loads was confirmed by tensile testing. These membranes were tested alongside animal cartilage, currently the strongest available myringoplasty graft as well as paper, which is commonly used for simpler procedures. Silk membranes showed resonant frequencies within the human hearing range and a higher vibrational amplitude than cartilage, suggesting that silk may offer good acoustic energy transfer characteristics. Silk membranes were also highly resistant to simulated pressure changes in the middle ear, suggesting they can resist retraction, a common cause of graft failure resulting from chronic negative pressures in the middle ear. Part of this strength can be explained by the substantially higher modulus of silk films compared with cartilage. This allows for the production of films that are much thinner than cartilage, with superior acoustic properties, but that still provide the same level of mechanical support as thicker cartilage. Together, these in vitro results suggest that silk membranes may provide good hearing outcomes while offering similar levels of mechanical support to the reconstructed middle ear.

  3. Flow and fouling in membrane filters: Effects of membrane morphology

    NASA Astrophysics Data System (ADS)

    Sanaei, Pejman; Cummings, Linda J.

    2015-11-01

    Membrane filters are widely-used in microfiltration applications. Many types of filter membranes are produced commercially, for different filtration applications, but broadly speaking the requirements are to achieve fine control of separation, with low power consumption. The answer to this problem might seem obvious: select the membrane with the largest pore size and void fraction consistent with the separation requirements. However, membrane fouling (an inevitable consequence of successful filtration) is a complicated process, which depends on many parameters other than membrane pore size and void fraction; and which itself greatly affects the filtration process and membrane functionality. In this work we formulate mathematical models that can (i) account for the membrane internal morphology (internal structure, pore size & shape, etc.); (ii) fouling of membranes with specific morphology; and (iii) make some predictions as to what type of membrane morphology might offer optimum filtration performance.

  4. Performance of a Cross-Flow Humidifier with a High Flux Water Vapor Transport Membrane

    SciTech Connect

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-30

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  5. Performance of a cross-flow humidifier with a high flux water vapor transport membrane

    NASA Astrophysics Data System (ADS)

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-01

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  6. Does medical students’ clinical performance affect their actual performance during medical internship?

    PubMed Central

    Han, Eui-Ryoung; Chung, Eun-Kyung

    2016-01-01

    INTRODUCTION This study examines the relationship between the clinical performance of medical students and their performance as doctors during their internships. METHODS This retrospective study involved 63 applicants of a residency programme conducted at Chonnam National University Hospital, South Korea, in November 2012. We compared the performance of the applicants during their internship with their clinical performance during their fourth year of medical school. The performance of the applicants as interns was periodically evaluated by the faculty of each department, while their clinical performance as fourth-year medical students was assessed using the Clinical Performance Examination (CPX) and the Objective Structured Clinical Examination (OSCE). RESULTS The performance of the applicants as interns was positively correlated with their clinical performance as fourth-year medical students, as measured by the CPX and OSCE. The performance of the applicants as interns was moderately correlated with the patient-physician interaction items addressing communication and interpersonal skills in the CPX. CONCLUSION The clinical performance of medical students during their fourth year in medical school was related to their performance as medical interns. Medical students should be trained to develop good clinical skills through actual encounters with patients or simulated encounters using manikins, to enable them to become more competent doctors. PMID:26768172

  7. Comparison of the performance of natural latex membranes prepared with different procedures and PTFE membrane in guided bone regeneration (GBR) in rabbits.

    PubMed

    Moura, Jonas M L; Ferreira, Juliana F; Marques, Leonardo; Holgado, Leandro; Graeff, Carlos F O; Kinoshita, Angela

    2014-09-01

    This work assessed the performance of membranes made of natural latex extracted from Hevea brasiliensis prepared with three different methods: polymerized immediately after collection without the use of ammonia (L1); polymerized after preservation in ammonia solution (L2); and polymerized after storage in ammonia, followed by Soxhlet technique for the extraction of substances (L3). Polytetrafluoroethylene (PTFE) membrane was used as control. Two 10-mm diameter bone defects were surgically made in the calvaria of thirty adult male New Zealand rabbits. Defects (total n = 60) were treated with guided bone regeneration (GBR) using L1, L2, L3 or PTFE membranes (n = 15 for each membrane). Ten animals were euthanized after 7, 20 and 60 days postoperatively so that five samples (n = 5) of each treatment were collected at each time, and bone regeneration was assessed microscopically. The microscopic analysis revealed defects filled with blood clot and new bone formation at the margins of the defect in all 7-day samples, while 20-day defects were mainly filled with fibrous connective tissue. After 60 days defects covered with L1 membranes showed a significantly larger bone formation area in comparison to the other groups (P < 0.05, ANOVA, Tukey). Additionally, bone tissue hypersensitization for L1 and PTFE membranes was also investigated in six additional rabbits. The animals were subjected to the same surgical procedure for the confection of one 10-mm diameter bone defect that was treated with L1 (n = 3) or PTFE (n = 3). Fifty-three days later, a second surgery was performed to make a second defect, which was treated with the same type of membrane used in the first surgery. Seven days later, the animals were euthanized and samples analyzed. No differences among L1 and PTFE samples collected from sensitized and non-sensitized animals were found (P > 0.05, Kruskal-Wallis). Therefore, the results demonstrated that latex membranes presented performance

  8. Tespa1 is a novel component of mitochondria-associated endoplasmic reticulum membranes and affects mitochondrial calcium flux.

    PubMed

    Matsuzaki, Hiroshi; Fujimoto, Takahiro; Tanaka, Masatoshi; Shirasawa, Senji

    2013-04-12

    Regulation of intracellular Ca(2+) concentration is critical in numerous biological processes. Inositol 1,4,5-trisphosphate receptor (IP3R) functions as the Ca(2+) release channel on endoplasmic reticulum (ER) membranes. Much attention has been dedicated to mitochondrial Ca(2+) uptake via mitochondria-associated ER membranes (MAM) which is involved in intracellular Ca(2+) homeostasis; however, the molecular mechanisms that link the MAM to mitochondria still remain elusive. We previously reported that Tespa1 (thymocyte-expressed, positive selection-associated gene 1) expressed in lymphocytes physically interacts with IP3R. In this study, we first performed double-immunocytochemical staining of Tespa1 with a mitochondrial marker or an ER marker on an acute T lymphoblastic leukemia cell line, Jurkat cells, by using anti-ATP synthase or anti-calnexin antibody, respectively, and demonstrated that Tespa1 was localized very close to mitochondria and the Tespa1 localization was overlapped with restricted portion of ER. Next, we examined the effects of Tespa1 on the T cell receptor (TCR) stimulation-induced Ca(2+) flux by using Ca(2+) imaging in Jurkat cells. Reduction of Tespa1 protein by Tespa1-specific siRNA diminished TCR stimulation-induced Ca(2+) flux into both mitochondria and cytoplasm through the analyses of the mitochondrial Ca(2+) indicator (Rhod-2) and the cytoplasmic Ca(2+) indicator (Fluo-4), respectively. Furthermore, co-immunoprecipitation assay in HEK293 cells revealed that exogenous Tespa1 protein physically interacted with a MAM-associated protein, GRP75 (glucose-regulated protein 75), but not with an outer mitochondrial membrane protein, VDAC1 (voltage-dependent anion channel 1). All these results suggested that Tespa1 will participate in the molecular link between IP3R-mediated Ca(2+) release and mitochondrial Ca(2+) uptake in the MAM compartment.

  9. Biocompatibility and functional performance of a polyethylene glycol acid-grafted cellulosic membrane for hemodialysis.

    PubMed

    Sirolli, V; Di Stante, S; Stuard, S; Di Liberato, L; Amoroso, L; Cappelli, P; Bonomini, M

    2000-06-01

    In order to improve the biochemical reactivity of the cellulose polymer, which is mainly attributed to the presence of surface hydroxyl groups, derivatized cellulosic membranes have been engineered replacing or masking some or all of the hydroxyl groups in the manufacturing process of the membrane. The present study was set up to analyze both biocompatibility and functional performance of two different derivatized cellulosic membranes (cellulose diacetate; polyethylene glycol, PEG, acid-grafted cellulose) as compared to a synthetic membrane (polymethylmethacrylate, PMMA). Cellulose diacetate is prepared by substituting hydroxyl groups with acetyl groups; PEG cellulose is obtained by grafting PEG chains onto the cellulosic polymer with a smaller amount of substitution than cellulose diacetate. While the three dialyzers provided similar urea and creatinine removal, the dialyzer containing cellulose diacetate showed a reduced ability to remove 32-microglobulin compared to that containing PEG cellulose or PMMA. A transient reduction in leukocyte count was observed for both derivatized cellulosic membranes. The neutrophil and monocyte counts throughout the entire dialysis session showed a closer parallelism with the cellular expression of the adhesive receptor CD 15s (sialyl-Lewis x molecule) than with CD11b/CD18 expression. Platelet activation, as indicated by the percentage of cells expressing the activation markers CD62P (P-selectin) and CD63 (gp53), occurred with all membranes at 15 min of dialysis and also with PMMA at 30 min. An increased formation of platelet-neutrophil and platelet-monocyte coaggregates was found at 15 and 30 min during dialysis with cellulose diacetate and PMMA but not with PEG cellulose. Generally in concomitance with the increase in platelet-neutrophil coaggregates, an increased hydrogen peroxide production by neutrophils occurred. Our results indicate that derivatizing cellulose may represent a useful approach to improve the biocompatibility

  10. Electromembrane extraction of tartrazine from food samples: Effects of nano-sorbents on membrane performance.

    PubMed

    Yaripour, Saeid; Mohammadi, Ali; Nojavan, Saeed

    2016-07-01

    In the present study, for the first time electromembrane extraction followed by high-performance liquid chromatography coupled with ultraviolet detection was developed and validated for the determination of tartrazine in some food samples. The parameters influencing electromembrane extraction were evaluated and optimized. The membrane consists of 1-octanol immobilized in the pores of a hollow fiber. As a driving force, a 30 V electrical field was applied to make the analyte migrate from sample solution with pH 3, through the supported liquid membrane into an acceptor solution with pH 10. Best preconcentration (enrichment factor >21) was obtained in extraction duration of 15 min. Effects of some solid nano-sorbents like carbon nanotubes and molecularly imprinted polymers on membrane performance and electromembrane extraction efficiency were evaluated. The method provided the linearity in the range 25-1000 ng/mL for tartrazine (R(2) > 0.9996) with repeatability range (RSD) between 3.8 and 8.5% (n = 3). The limits of detection and quantitation were 7.5 and 25 ng/mL, respectively. Finally, the method was applied to the determination and quantification of tartrazine from some food samples with relative recoveries in the range between 90 and 98%.

  11. Effect of gamma irradiation at intermediate doses on the performance of reverse osmosis membranes

    NASA Astrophysics Data System (ADS)

    Combernoux, Nicolas; Labed, Véronique; Schrive, Luc; Wyart, Yvan; Carretier, Emilie; Moulin, Philippe

    2016-07-01

    The goal of this study is to explain the degradation of Polyamide (PA) composite reverse osmosis membrane (RO) in function of the irradiation dose. Irradiations were performed with a gamma 60Co source in wet conditions and under oxygen atmosphere. For different doses of 0.2 and 0.5 MGy with a constant dose rate of 0.5 kGy h-1, RO membranes performances (NaCl retention, permeability) were studied before and after irradiation. ATR-FTIR, ion chromatography and gas chromatography were used to characterize structural modification. Results showed that the permeability of RO membranes irradiated at 0.2 MGy exhibited a small decrease, related to scissions of the PVA coating. However, retention did not change at this dose. At 0.5 MGy, permeability showed a large increase of a factor around 2 and retention began to decrease from 99% to 95%. Chromatography measurements revealed a strong link between permselectivity properties variation, ion leakage and oxygen consumption. Add to ATR-FTIR observations, these results emphasized that the cleavages of amide and ester bonds were observed at 0.5 MGy, more precisely the loss of hydrogen bonds between polyamide chains. By different analysis, modifications of the polysulfone layer occur until a dose of 0.2 MGy.

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

    SciTech Connect

    2010-07-01

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

  13. Layered conductive polymer on nylon membrane templates for high performance, thin-film supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Shi, HaoTian Harvey; Naguib, Hani E.

    2016-04-01

    Flexible Thin-film Electrochemical Capacitors (ECs) are emerging technology that plays an important role as energy supply for various electronics system for both present era and the future. Intrinsically conductive polymers (ICPs) are promising pseudo-capacitive materials as they feature both good electrical conductivity and high specific capacitance. This study focuses on the construction and characterization of ultra-high surface area porous electrodes based on coating of nano-sized conductive polymer materials on nylon membrane templates. Herein, a novel nano-engineered electrode material based on nylon membranes was presented, which allows the creation of super-capacitor devices that is capable of delivering competitive performance, while maintaining desirable mechanical characteristics. With the formation of a highly conductive network with the polyaniline nano-layer, the electrical conductivity was also increased dramatically to facilitate the charge transfer process. Cyclic voltammetry and specific capacitance results showed promising application of this type of composite materials for future smart textile applications.

  14. Performance assessment of a submerged membrane bioreactor using a novel microbial consortium.

    PubMed

    Chon, Kangmin; Lee, Kyungpyo; Kim, In-Soo; Jang, Am

    2016-06-01

    The performance of a submerged membrane bioreactor (MBR) with and without a novel microbial consortium (NMBR vs. CMBR) was compared to provide deeper insights into the effects of changes in water quality and dissolved organic matter (DOM) characteristics by a novel microbial consortium on the fouling characteristics of MBR processes. Despite similar operating conditions and identical DOM properties in the feed waters, NMBR exhibited a lower propensity to release polysaccharide-like compounds with low molecular weight by bacterial activities compared to CMBR. These compounds have a great fouling potential for MBR processes. Therefore, an increase in the transmembrane pressure (TMP) of NMBR (normalized TMP (TMP/TMP0): 1.14) was much slower and less significant than that observed in CMBR (TMP/TMP0: 2.61). These observations imply that the novel microbial consortium can efficiently mitigate membrane fouling by hydrophilic DOM in MBR processes.

  15. Investigation of cross-linked and additive containing polymer materials for membranes with improved performance in pervaporation and gas separation.

    PubMed

    Hunger, Katharina; Schmeling, Nadine; Jeazet, Harold B Tanh; Janiak, Christoph; Staudt, Claudia; Kleinermanns, Karl

    2012-10-22

    Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes.

  16. Investigation of Cross-Linked and Additive Containing Polymer Materials for Membranes with Improved Performance in Pervaporation and Gas Separation

    PubMed Central

    Hunger, Katharina; Schmeling, Nadine; Jeazet, Harold B. Tanh; Janiak, Christoph; Staudt, Claudia; Kleinermanns, Karl

    2012-01-01

    Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes. PMID:24958427

  17. To branch out or stay focused? Affective shifts differentially predict organizational citizenship behavior and task performance.

    PubMed

    Yang, Liu-Qin; Simon, Lauren S; Wang, Lei; Zheng, Xiaoming

    2016-06-01

    We draw from personality systems interaction (PSI) theory (Kuhl, 2000) and regulatory focus theory (Higgins, 1997) to examine how dynamic positive and negative affective processes interact to predict both task and contextual performance. Using a twice-daily diary design over the course of a 3-week period, results from multilevel regression analysis revealed that distinct patterns of change in positive and negative affect optimally predicted contextual and task performance among a sample of 71 employees at a medium-sized technology company. Specifically, within persons, increases (upshifts) in positive affect over the course of a workday better predicted the subsequent day's organizational citizenship behavior (OCB) when such increases were coupled with decreases (downshifts) in negative affect. The optimal pattern of change in positive and negative affect differed, however, in predicting task performance. That is, upshifts in positive affect over the course of the workday better predicted the subsequent day's task performance when such upshifts were accompanied by upshifts in negative affect. The contribution of our findings to PSI theory and the broader affective and motivation regulation literatures, along with practical implications, are discussed. (PsycINFO Database Record

  18. Performance-Based Occupational Affective Behavior Analysis (OABA). Implementation and Supporting Research.

    ERIC Educational Resources Information Center

    Pucel, David J.; And Others

    This document contains two sections: implementation of the performance-based Occupational Affective Behavior Analysis (OABA), and supporting research. Section 1 presents OABA, an analytic procedure designed to identify those affective behaviors important to success in an occupation, and gives directions on how to implement the procedure. The…

  19. Investigating Learner Affective Performance in Web-Based Learning by Using Entrepreneurship as a Metaphor

    ERIC Educational Resources Information Center

    Liu, Ming-Chou; Chi, Ming-Hsiao

    2012-01-01

    In the era of the Internet, factors which influence effective learning in a Web-based learning environment are well worth exploring. In addition to knowledge acquisition and skills training, affect is also an important factor, since successful learning requires excellent affective performance. Thus this study focuses on learners' affective…

  20. Psychological Factor Affecting English Speaking Performance for the English Learners in Indonesia

    ERIC Educational Resources Information Center

    Haidara, Youssouf

    2016-01-01

    In every learning situation or environment, human psychology plays a significant role. English speaking is a language skill that is highly affected by human psychology. This research aimed at describing the psychological factor that affects negatively the English speaking performance for the English learners in Indonesia. A descriptive qualitative…

  1. Using a False Biofeedback Methodology to Explore Relationships between Learners' Affect, Metacognition, and Performance

    ERIC Educational Resources Information Center

    Strain, Amber Chauncey; Azevedo, Roger; D'Mello, Sidney K.

    2013-01-01

    We used a false-biofeedback methodology to manipulate physiological arousal in order to induce affective states that would influence learners' metacognitive judgments and learning performance. False-biofeedback is a method used to induce physiological arousal (and resultant affective states) by presenting learners with audio stimuli of false heart…

  2. Happy Places, Horrible Times, and Scary Learners: Affective Performances and Sticky Objects in Inclusive Classrooms

    ERIC Educational Resources Information Center

    Naraian, Srikala; Khoja-Moolji, Shenila

    2016-01-01

    Drawing on data from two studies conducted in US public schools, this paper traces the affective productions and performances of teachers to illustrate the role of affect in delineating (non)normative pedagogical practices in inclusive classrooms. Occupying a borderland space in narrative inquiry that permitted the straddling of differing…

  3. PEG-imbedded PEO membrane developed by a novel highly efficient strategy toward superior gas transport performance.

    PubMed

    Quan, Shuai; Tang, Yu Pan; Wang, Zhen Xing; Jiang, Zai Xing; Wang, Rong Guo; Liu, Yu Yan; Shao, Lu

    2015-03-01

    Low-molecular-weight poly(ethylene glycol) (PEG) is deliberately incorporated into synthesized swellable poly(ethylene oxide) (PEO) membranes via a facile post-treatment strategy. The membranes exhibit both larger fractional free volume (FFV) and a higher content of CO2-philic building units, resulting in significant increments in both CO2 permeability and CO2/H2 selectivity. The separation performance correlates nicely with the microstructure of the membranes. This study may provide useful insights in the formation and mass transport behavior of highly efficient polymeric membranes applicable to clean energy purification and CO2 capture, and possibly bridge the material-induced technology gap between academia and industry.

  4. Assessing membrane fouling and the performance of pilot-scale membrane bioreactor (MBR) to treat real municipal wastewater during winter season in Nordic regions.

    PubMed

    Gurung, Khum; Ncibi, Mohamed Chaker; Sillanpää, Mika

    2017-02-01

    In this study, the performance of a pilot-scale membrane bioreactor (MBR) to treat real municipal wastewater was assessed at low temperatures (7 to 20°C) in Nordic regions. First, the effect of low temperatures on membrane fouling was evaluated by monitoring trans-membrane pressure. A significant membrane fouling was observed when the sludge temperature inside the MBR unit was below 10°C with a 75% permeability drop, thus indicating high deterioration of the membrane performance at low temperatures. Moreover, increasing values of sludge volume index (SVI) during low temperatures showed high deterioration of sludge settleability. As for the pollution removal, MBR achieved high performances primarily for pathogens and emerging micropollutants. The average log reductions of 1.82, 3.02, and 1.94 log units were achieved for norovirus GI, norovirus GII, and adenoviruses, respectively. Among the four trace organic compounds (TrOCs), the average removal efficiencies of bisoprolol, diclofenac and bisphenol A were 65%, 38%, and >97%, respectively. However, carbamazepine was not efficiently removed (-89% to 28%). Regarding trace metals, an average removal of >80% was achieved for Cd, Pb, and V. For the rest of the metals, the removal capacities were between 30 and 60%.

  5. Preparation, characterization and performance of poly(m-phenylene isophthalamide)/organically modified montmorillonite nanocomposite membranes in removal of perfluorooctane sulfonate.

    PubMed

    Luo, Qin; Liu, Yanxia; Liu, Guixia; Zhao, Changwei

    2016-08-01

    Nanocomposite membranes containing poly(m-phenylene isophthalamide) (PMIA) and organically modified montmorillonite (OMMT) were prepared by a combination of solution dispersion and wet-phase inversion methods, and the effects of OMMT addition on the properties and performance of fabricated nanofiltration membranes were investigated. The membranes were characterized by contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis, and zeta potential. The performance of the membranes was elucidated by the removal of perfluorooctane sulfonate (PFOS) at neutral pH. Increasing OMMT concentration improved the thermal stability and hydrophilicity of the membranes. The permeation and rejection of PFOS were significantly improved. The performance of fabricated nanofiltration membranes in removal of PFOS varied depending on the solute and membrane properties as well as solution conditions. Finally, a comparison between fabricated membranes and a commercial NF membrane (ESNA1-K1, Hydecanme) proved that the OMMT addition is a convenient procedure for producing nanocomposite membranes with superior properties and performance.

  6. U.S. DOE Progress Towards Developing Low-Cost, High Performance, Durable Polymer Electrolyte Membranes for Fuel Cell Applications

    PubMed Central

    Houchins, Cassidy; Kleen, Greg J.; Spendelow, Jacob S.; Kopasz, John; Peterson, David; Garland, Nancy L.; Ho, Donna Lee; Marcinkoski, Jason; Martin, Kathi Epping; Tyler, Reginald; Papageorgopoulos, Dimitrios C.

    2012-01-01

    Low cost, durable, and selective membranes with high ionic conductivity are a priority need for wide-spread adoption of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Electrolyte membranes are a major cost component of PEMFC stacks at low production volumes. PEMFC membranes also impose limitations on fuel cell system operating conditions that add system complexity and cost. Reactant gas and fuel permeation through the membrane leads to decreased fuel cell performance, loss of efficiency, and reduced durability in both PEMFCs and DMFCs. To address these challenges, the U.S. Department of Energy (DOE) Fuel Cell Technologies Program, in the Office of Energy Efficiency and Renewable Energy, supports research and development aimed at improving ion exchange membranes for fuel cells. For PEMFCs, efforts are primarily focused on developing materials for higher temperature operation (up to 120 °C) in automotive applications. For DMFCs, efforts are focused on developing membranes with reduced methanol permeability. In this paper, the recently revised DOE membrane targets, strategies, and highlights of DOE-funded projects to develop new, inexpensive membranes that have good performance in hot and dry conditions (PEMFC) and that reduce methanol crossover (DMFC) will be discussed. PMID:24958432

  7. U.S. DOE Progress Towards Developing Low-Cost, High Performance, Durable Polymer Electrolyte Membranes for Fuel Cell Applications.

    PubMed

    Houchins, Cassidy; Kleen, Greg J; Spendelow, Jacob S; Kopasz, John; Peterson, David; Garland, Nancy L; Ho, Donna Lee; Marcinkoski, Jason; Martin, Kathi Epping; Tyler, Reginald; Papageorgopoulos, Dimitrios C

    2012-12-18

    Low cost, durable, and selective membranes with high ionic conductivity are a priority need for wide-spread adoption of polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Electrolyte membranes are a major cost component of PEMFC stacks at low production volumes. PEMFC membranes also impose limitations on fuel cell system operating conditions that add system complexity and cost. Reactant gas and fuel permeation through the membrane leads to decreased fuel cell performance, loss of efficiency, and reduced durability in both PEMFCs and DMFCs. To address these challenges, the U.S. Department of Energy (DOE) Fuel Cell Technologies Program, in the Office of Energy Efficiency and Renewable Energy, supports research and development aimed at improving ion exchange membranes for fuel cells. For PEMFCs, efforts are primarily focused on developing materials for higher temperature operation (up to 120 °C) in automotive applications. For DMFCs, efforts are focused on developing membranes with reduced methanol permeability. In this paper, the recently revised DOE membrane targets, strategies, and highlights of DOE-funded projects to develop new, inexpensive membranes that have good performance in hot and dry conditions (PEMFC) and that reduce methanol crossover (DMFC) will be discussed.

  8. Enhancement of fuel cell performance with less-water dependent composite membranes having polyoxometalate anchored nanofibrous interlayer

    NASA Astrophysics Data System (ADS)

    Abouzari-lotf, Ebrahim; Jacob, Mohan V.; Ghassemi, Hossein; Ahmad, Arshad; Nasef, Mohamed Mahmoud; Zakeri, Masoumeh; Mehdipour-Ataei, Shahram

    2016-09-01

    Polyoxometalate immobilized nanofiber was used to fabricate low gas permeable layer for composite membranes designed for proton exchange membrane fuel cell (PEMFC) operating at low relative humidity (RH). The composite membranes revealed enhanced proton conductivity in dry conditions compared with state-of-the-art pristine membrane (Nafion 112, N112). This was coupled with a low fuel crossover inheriting the composite membranes about 100 mV higher OCV than N112 when tested in PEMFC at 60 °C and 40% RH. A maximum power density of up to 930 mW cm-2 was also achieved which is substantially higher than the N112 under similar conditions (577 mW cm-2). Such remarkable performance enhancement along with undetectable leaching of immobilized polyoxometalate, high dimensional stability and low water uptake of the composite membranes suggest a strong potential for PEMFC under low RH operation.

  9. Effect of Polyvnylpyrrolidone (PVP) in Binary Solution on the Performance of Polyethersulfone Hollow Fibre Membrane for Sodium Chloride Separation

    NASA Astrophysics Data System (ADS)

    Bolong, N.; Ismail, A. F.; Salim, M. R.

    2010-03-01

    In membrane preparation, phase inversion is a versatile technique that allow polymer to be transformed from liquid to a solid state in a controlled manner. The preparation and process involves many factors and parameters specifically in fabricating hollow fibre membrane. In this study, dope solution factor in the process of fabricating hollow fibre membrane were explored. The effects of polymer concentration and polyvinylpyrrolidone (PVP) as additive in the dope solution on the morphology and separation performance were found able to produced high porous membranes, well interconnected pores and surface properties. Employing polyethersulfone (PES) as polymer, hollow fibre membranes were fabricated using N-methyl-2-pyrrolidone (NMP) as solvent and using water as the external coagulant. Finally the fabricated ultrafiltration membranes were characterized and evaluated based on solute transport concentration (sodium chloride) and pure water permeation properties.

  10. Performing a secondary executive task with affective stimuli interferes with decision making under risk conditions.

    PubMed

    Gathmann, Bettina; Pawlikowski, Mirko; Schöler, Tobias; Brand, Matthias

    2014-05-01

    Previous studies demonstrated that executive functions are crucial for advantageous decision making under risk and that therefore decision making is disrupted when working memory capacity is demanded while working on a decision task. While some studies also showed that emotions can affect decision making under risk, it is unclear how affective processing and executive functions predict decision-making performance in interaction. The current experimental study used a between-subjects design to examine whether affective pictures (positive and negative pictures compared to neutral pictures), included in a parallel executive task (working memory 2-back task), have an impact on decision making under risk as assessed by the Game of Dice Task (GDT). Moreover, the performance GDT plus 2-back task was compared to the performance in the GDT without any additional task (GDT solely). The results show that the performance in the GDT differed between groups (positive, negative, neutral, and GDT solely). The groups with affective pictures, especially those with positive pictures in the 2-back task, showed more disadvantageous decisions in the GDT than the groups with neutral pictures and the group performing the GDT without any additional task. However, executive functions moderated the effect of the affective pictures. Regardless of affective influence, subjects with good executive functions performed advantageously in the GDT. These findings support the assumption that executive functions and emotional processing interact in predicting decision making under risk.

  11. miRNAs in the vitreous humor of patients affected by idiopathic epiretinal membrane and macular hole

    PubMed Central

    Ragusa, Marco; Barbagallo, Cristina; Longo, Antonio; Avitabile, Teresio; Uva, Maurizio G.; Bonfiglio, Vincenza; Toro, Mario D.; Caltabiano, Rosario; Mariotti, Cesare; Boscia, Francesco; Romano, Mario; Di Pietro, Cinzia; Barbagallo, Davide; Purrello, Michele; Reibaldi, Michele

    2017-01-01

    Purpose The aim of the present study was to assess the expression of miRNAs in the Vitreous Humor (VH) of patients with Macular Hole (MH) and Epiretinal Membrane (ERM) compared to a control group. Methods In this prospective, comparative study, 2-ml of VH was extracted from the core of the vitreous chamber in consecutive patients who underwent standard vitrectomy for ERM and MH. RNA was extracted and TaqMan® Low Density Arrays (TLDAs) were used to profile the transcriptome of 754 miRNAs. Results were validated by single TaqMan® assays. Finally, we created a biological network of differentially expressed miRNA targets and their nearest neighbors. Results Overall 10 eyes with MH, 16 eyes with idiopathic ERM and 6 controls were enrolled in the study. Profiling data identified 5 miRNAs differentially expressed in patients affected by MH and ERM with respect to controls. Four were downregulated (miR-19b, miR-24, miR-155, miR-451) and 1 was downregulated (miR-29a); TaqMan® assays of the VH of patients affected by MH and ERM, with respect to controls, showed that the most differentially expressed were miR-19b (FC -9.13, p:<0.00004), mir-24 (FC -7.52, p:<0.004) and miR-142-3p (FC -5.32, p:<0.011). Our network data showed that deregulation of differentially expressed miRNAs induces an alteration of several pathways associated with genes involved in both MH and ERM. Conclusion The present study suggests that disregulation of miR-19b, miR-24 and miR-142-3p, might be related to the alterations that characterize patients affected by MH and ERM. PMID:28328945

  12. Effects of bolt torque and contact resistance on the performance of the polymer electrolyte membrane electrolyzers

    NASA Astrophysics Data System (ADS)

    Selamet, Omer F.; Ergoktas, M. Said

    2015-05-01

    The effect of bolt torque and contact resistance on the performance of Proton Exchange Membrane (PEM) Electrolyzers are investigated by a 50 cm2 cell. The cell is designed and manufactured in house. The performance and contact resistance of the cell with three different gasket materials for demanding bolt torques are measured. The pressure distribution inside the cell is obtained by using pressure sensitive films. The pressure acting on the membrane electrode assembly (MEA) is calculated by analyzing and quantifying intensities of pressure film images. 3D plots of pressure distribution for predefined bolt torque values are obtained to understand the pressure distribution over the active area. The performance of the cell is enhanced when bolt torque is increased. However, beyond a value, relatively weak cell components such as diffusion layers are damaged and performance loss is observed due to the mass transfer limitations. The best efficiency is reached at 15 Nm bolt torque for Polytetrafluoroethylene (PTFE) and Ethylene Propylene Diene Monomer (EPDM) gaskets. For silicon gasket best efficiency is reached at 15 Nm at lower current densities and at 10 Nm at higher current densities. Increasing clamping pressure is found to be developing more contact points between the interfaces and results in decrease in contact resistance inside the cell.

  13. PREPARATION AND APPLICATION OF HIGH PERFORMANCE SILICONE RUBBER MIXED MATRIX MEMBRANES FOR ETHANOL-WATER PERVAPORATION

    EPA Science Inventory

    Polydimethyl siloxane (PDMS) and zeolite incorporated mixed matrix materials are gaining importance in a variety of applications including membrane separation. PDMS based membranes are used in pervaporation (PV), a membrane technology, for the selective removal of organics such ...

  14. Morphology-properties relationship of gas plasma treated hydrophobic meso-porous membranes and their improved performance for desalination by membrane distillation

    NASA Astrophysics Data System (ADS)

    Dumée, Ludovic F.; Alglave, Hortense; Chaffraix, Thomas; Lin, Bao; Magniez, Kevin; Schütz, Jürg

    2016-02-01

    The impact on performance of the surface energy and roughness of membrane materials used for direct contact membrane distillation are critical but yet poorly investigated parameters. The capacity to alter the wettability of highly hydrophobic materials such as poly(tetra-fluoro-ethylene) (PTFE) by gas plasma treatments is reported in this paper. An equally important contribution from this investigation arises from illustrating how vaporized material from the treated sample participates after a short while in the composition of the plasma and fundamentally changes the result of surface chemistry processes. The water contact angle across the hydrophobic membranes is generally controlled by varying the plasma gas conditions, such as the plasma power, chamber pressure and irradiation duration. Changes to surface porosity and roughness of the bulk material as well as the surface chemistry, through specific and partial de-fluorination of the surface were detected and systematically studied by Fourier transform infra-red analysis and scanning electron microscopy. It was found that the rupture of fibrils, formed during membrane processing by thermal-stretching, led to the formation of a denser surface composed of nodules similar to these naturally acting as bridging points across the membrane material between fibrils. This structural change has a profound and impart a permanent effect on the permeation across the modified membranes, which was found to be enhanced by up to 10% for long plasma exposures while the selectivity of the membranes was found to remain unaffected by the treatment at a level higher than 99.99%. This is the first time that an investigation demonstrates how the permeation characteristics of these membranes is directly related to data from spectral, morphological and surface charge analyses, which provide new insights on the impact of plasma treatments on both, the surface charge and roughness, of PTFE porous materials.

  15. Preparation of Sulfobetaine-Grafted PVDF Hollow Fiber Membranes with a Stably Anti-Protein-Fouling Performance

    PubMed Central

    Li, Qian; Lin, Han-Han; Wang, Xiao-Lin

    2014-01-01

    Based on a two-step polymerization method, two sulfobetaine-based zwitterionic monomers, including 3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide (MPDSAH) and 2-(methacryloyloxyethyl) ethyl-dimethyl-(3-sulfopropyl) ammonium (MEDSA), were successfully grafted from poly(vinylidene fluoride) (PVDF) hollow fiber membrane surfaces in the presence of N,N′-methylene bisacrylamide (MBAA) as a cross-linking agent. The mechanical properties of the PVDF membrane were improved by the zwitterionic surface layers. The surface hydrophilicity of PVDF membranes was significantly enhanced and the polyMPDSAH-g-PVDF membrane showed a higher hydrophilicity due to the higher grafting amount. Compared to the polyMEDSA-g-PVDF membrane, the polyMPDSAH-g-PVDF membrane showed excellent significantly better anti-protein-fouling performance with a flux recovery ratio (RFR) higher than 90% during the cyclic filtration of a bovine serum albumin (BSA) solution. The polyMPDSAH-g-PVDF membrane showed an obvious electrolyte-responsive behavior and its protein-fouling-resistance performance was improved further during the filtration of the protein solution with 100 mmol/L of NaCl. After cleaned with a membrane cleaning solution for 16 days, the grafted MPDSAH layer on the PVDF membrane could be maintain without any chang; however, the polyMEDSA-g-PVDF membrane lost the grafted MEDSA layer after this treatment. Therefore, the amide group of sulfobetaine, which contributed significantly to the higher hydrophilicity and stability, was shown to be imperative in modifying the PVDF membrane for a stable anti-protein-fouling performance via the two-step polymerization method. PMID:24957171

  16. Preparation of Sulfobetaine-Grafted PVDF Hollow Fiber Membranes with a Stably Anti-Protein-Fouling Performance.

    PubMed

    Li, Qian; Lin, Han-Han; Wang, Xiao-Lin

    2014-04-08

    Based on a two-step polymerization method, two sulfobetaine-based zwitterionic monomers, including 3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide (MPDSAH) and 2-(methacryloyloxyethyl) ethyl-dimethyl-(3-sulfopropyl) ammonium (MEDSA), were successfully grafted from poly(vinylidene fluoride) (PVDF) hollow fiber membrane surfaces in the presence of N,N'-methylene bisacrylamide (MBAA) as a cross-linking agent. The mechanical properties of the PVDF membrane were improved by the zwitterionic surface layers. The surface hydrophilicity of PVDF membranes was significantly enhanced and the polyMPDSAH-g-PVDF membrane showed a higher hydrophilicity due to the higher grafting amount. Compared to the polyMEDSA-g-PVDF membrane, the polyMPDSAH-g-PVDF membrane showed excellent significantly better anti-protein-fouling performance with a flux recovery ratio (RFR) higher than 90% during the cyclic filtration of a bovine serum albumin (BSA) solution. The polyMPDSAH-g-PVDF membrane showed an obvious electrolyte-responsive behavior and its protein-fouling-resistance performance was improved further during the filtration of the protein solution with 100 mmol/L of NaCl. After cleaned with a membrane cleaning solution for 16 days, the grafted MPDSAH layer on the PVDF membrane could be maintain without any chang; however, the polyMEDSA-g-PVDF membrane lost the grafted MEDSA layer after this treatment. Therefore, the amide group of sulfobetaine, which contributed significantly to the higher hydrophilicity and stability, was shown to be imperative in modifying the PVDF membrane for a stable anti-protein-fouling performance via the two-step polymerization method.

  17. Performance of a membrane bioreactor used for the treatment of wastewater contaminated with heavy metals.

    PubMed

    Katsou, Evina; Malamis, Simos; Loizidou, Maria

    2011-03-01

    In this work the performance of a Membrane bioreactor (MBR) was assessed for the removal of 3-15 mg/l of copper, lead, nickel and zinc from wastewater. The average removal efficiencies accomplished by the MBR system were 80% for Cu(II), 98% for Pb(II), 50% for Ni(II) and 77% for Zn(II). The addition of 5 g/l vermiculite into the biological reactor enhanced metal removal to 88% for copper, 85% for zinc and 60% for nickel due to adsorption of metal ions on the mineral, while it reduced biomass inhibition and increased biomass growth. The metal ions remaining in soluble form penetrated into the permeate, while those attached to sludge flocs were effectively retained by the ultrafiltration membranes. The average heterotrophic biomass inhibition was 50%, while it reduced to 29% when lower metal concentrations were fed into the reactor in the presence of vermiculite. The respective autotrophic biomass inhibition was 70% and 36%. The presence of heavy metals and vermiculite in the mixed liquor adversely impacted on membrane fouling.

  18. Effects of biofouling on ion transport through cation exchange membranes and microbial fuel cell performance.

    PubMed

    Choi, Mi-Jin; Chae, Kyu-Jung; Ajayi, Folusho F; Kim, Kyoung-Yeol; Yu, Hye-Weon; Kim, Chang-Won; Kim, In S

    2011-01-01

    This study examines the effects of biofouling on the electrochemical properties of cation exchange membranes (CEMs), such as membrane electrical resistance (MER), specific proton conductivity (SC), and ion transport number (t(+)), in addition to on microbial fuel cell (MFC) performance. CEM biofouling using a 15.5 ± 4.6 μm biofilm was found to slightly increase the MER from 15.65 Ω cm(2) (fresh Nafion) to 19.1 Ω cm(2), whereas an increase of almost two times was achieved when the electrolyte was changed from deionized water to an anolyte containing a high cation concentration supporting bacterial growth. The simple physical cleaning of CEMs had little effect on the Coulombic efficiency (CE), whereas replacing a biofouled CEM with new one resulted in considerable increase of up to 59.3%, compared to 45.1% for a biofouled membrane. These results clearly suggest the internal resistance increase of MFC was mainly caused by the sulfonate functional groups of CEM being occupied with cations contained in the anolyte, rather than biofouling itself.

  19. Performance evaluation of microbial electrochemical systems operated with Nafion and supported ionic liquid membranes.

    PubMed

    Koók, László; Nemestóthy, Nándor; Bakonyi, Péter; Zhen, Guangyin; Kumar, Gopalakrishnan; Lu, Xueqin; Su, Lianghu; Saratale, Ganesh Dattatraya; Kim, Sang-Hyoun; Gubicza, László

    2017-05-01

    In this work, the performance of dual-chamber microbial fuel cells (MFCs) constructed either with commonly used Nafion(®) proton exchange membrane or supported ionic liquid membranes (SILMs) was assessed. The behavior of MFCs was followed and analyzed by taking the polarization curves and besides, their efficiency was characterized by measuring the electricity generation using various substrates such as acetate and glucose. By using the SILMs containing either [C6mim][PF6] or [Bmim][NTf2] ionic liquids, the energy production of these MFCs from glucose was comparable to that obtained with the MFC employing polymeric Nafion(®) and the same substrate. Furthermore, the MFC operated with [Bmim][NTf2]-based SILM demonstrated higher energy yield in case of low acetate loading (80.1 J g(-1) CODin m(-2) h(-1)) than the one with the polymeric Nafion(®) N115 (59 J g(-1) CODin m(-2) h(-1)). Significant difference was observed between the two SILM-MFCs, however, the characteristics of the system was similar based on the cell polarization measurements. The results suggest that membrane-engineering applying ionic liquids can be an interesting subject field for bioelectrochemical system research.

  20. N-linked glycans do not affect plasma membrane localization of multidrug resistance protein 4 (MRP4) but selectively alter its prostaglandin E2 transport activity.

    PubMed

    Miah, M Fahad; Conseil, Gwenaëlle; Cole, Susan P C

    2016-01-22

    Multidrug resistance protein 4 (MRP4) is a member of subfamily C of the ATP-binding cassette superfamily of membrane transport proteins. MRP4 mediates the ATP-dependent efflux of many endogenous and exogenous solutes across the plasma membrane, and in polarized cells, it localizes to the apical or basolateral plasma membrane depending on the tissue type. MRP4 is a 170 kDa glycoprotein and here we show that MRP4 is simultaneously N-glycosylated at Asn746 and Asn754. Furthermore, confocal immunofluorescence studies showed that N-glycans do not affect MRP4's apical membrane localization in polarized LLC-PK1 cells or basolateral membrane localization in polarized MDCKI cells. However, vesicular transport assays showed that N-glycans differentially affect MRP4's ability to transport prostaglandin E2, but not estradiol glucuronide. Together these data indicate that N-glycosylation at Asn746 and Asn754 is not essential for plasma membrane localization of MRP4 but cause substrate-selective effects on its transport activity.

  1. Some Factors That Affecting the Performance of Mathematics Teachers in Junior High School in Medan

    ERIC Educational Resources Information Center

    Manullang, Martua; Rajagukguk, Waminton

    2016-01-01

    Some Factor's That Affecting The Mathematic Teacher Performance For Junior High School In Medan. This research will examine the effect of direct and indirect of the Organizational Knowledge towards the achievement motivation, decision making, organizational commitment, the performance of mathematics teacher. The research method is a method of…

  2. Using Representations in Geometry: A Model of Students' Cognitive and Affective Performance

    ERIC Educational Resources Information Center

    Panaoura, Areti

    2014-01-01

    Self-efficacy beliefs in mathematics, as a dimension of the affective domain, are related with students' performance on solving tasks and mainly on overcoming cognitive obstacles. The present study investigated the interrelations of cognitive performance on geometry and young students' self-efficacy beliefs about using representations for solving…

  3. Centrality and Charisma: Comparing How Leader Networks "and" Attributions Affect Team Performance

    ERIC Educational Resources Information Center

    Balkundi, Prasad; Kilduff, Martin; Harrison, David A.

    2011-01-01

    When leaders interact in teams with their subordinates, they build social capital that can have positive effects on team performance. Does this social capital affect team performance because subordinates come to see the leader as charismatic? We answered this question by examining 2 models. First, we tested the charisma-to-centrality model…

  4. The Developmental Dynamics of Children's Academic Performance and Mothers' Homework-Related Affect and Practices

    ERIC Educational Resources Information Center

    Silinskas, Gintautas; Kiuru, Noona; Aunola, Kaisa; Lerkkanen, Marja-Kristiina; Nurmi, Jari-Erik

    2015-01-01

    This study investigated the longitudinal associations between children's academic performance and their mothers' affect, practices, and perceptions of their children in homework situations. The children's (n = 2,261) performance in reading and math was tested in Grade 1 and Grade 4, and the mothers (n = 1,476) filled out questionnaires on their…

  5. Affective Cues and Processing Strategy: Color-Coded Examination Forms Influence Performance.

    ERIC Educational Resources Information Center

    Sinclair, Robert C.; Soldat, Alexander S.; Mark, Melvin M.

    1998-01-01

    Argues that external cues provide affective information that influence processing strategy and, therefore, examination performance. Notes the differences in performance for two midterm examinations, identical, except that they were printed on blue and red paper. Discusses a method for appropriately adjusting scores to control for form effects.…

  6. Performance Assessment in CTE: Focusing on the Cognitive, Psychomotor ...and Affective Domains

    ERIC Educational Resources Information Center

    Washer, Bart; Cochran, Lori

    2012-01-01

    When a student is performing in the psychomotor domain, the authors believe the student is also performing in the cognitive domain (sequencing steps, evaluating the situation) and in the affective domain (appreciating a job well done, quality control, safety). As Dabney Doty, former instructor at the University of Central Missouri, stated, "There…

  7. The developmental dynamics of children's academic performance and mothers' homework-related affect and practices.

    PubMed

    Silinskas, Gintautas; Kiuru, Noona; Aunola, Kaisa; Lerkkanen, Marja-Kristiina; Nurmi, Jari-Erik

    2015-04-01

    This study investigated the longitudinal associations between children's academic performance and their mothers' affect, practices, and perceptions of their children in homework situations. The children's (n = 2,261) performance in reading and math was tested in Grade 1 and Grade 4, and the mothers (n = 1,476) filled out questionnaires on their affect, practices, and perceptions while their children were in Grades 2, 3, and 4. The results showed, first, that the more help in homework the mothers reported, the slower was the development of their children's academic performance from Grade 1 to Grade 4. This negative association was true especially if mothers perceived their children not to be able to work autonomously. Second, children's good academic performance in Grade 1 predicted mothers' perception of child's ability to be autonomous and positive affect in homework situations later on, whereas poor performance predicted mothers' negative affect, help, and monitoring. Finally, mothers' negative affect mediated the association between children's poor performance, maternal practices, and perceptions of their children.

  8. High-performance membrane-electrode assembly with an optimal polytetrafluoroethylene content for high-temperature polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jeong, Gisu; Kim, MinJoong; Han, Junyoung; Kim, Hyoung-Juhn; Shul, Yong-Gun; Cho, EunAe

    2016-08-01

    Although high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have a high carbon monoxide tolerance and allow for efficient water management, their practical applications are limited due to their lower performance than conventional low-temperature PEMFCs. Herein, we present a high-performance membrane-electrode assembly (MEA) with an optimal polytetrafluoroethylene (PTFE) content for HT-PEMFCs. Low or excess PTFE content in the electrode leads to an inefficient electrolyte distribution or severe catalyst agglomeration, respectively, which hinder the formation of triple phase boundaries in the electrodes and result in low performance. MEAs with PTFE content of 20 wt% have an optimal pore structure for the efficient formation of electrolyte/catalyst interfaces and gas channels, which leads to high cell performance of approximately 0.5 A cm-2 at 0.6 V.

  9. Constructing all carbon nanotube hollow fiber membranes with improved performance in separation and antifouling for water treatment.

    PubMed

    Wei, Gaoliang; Yu, Hongtao; Quan, Xie; Chen, Shuo; Zhao, Huimin; Fan, Xinfei

    2014-07-15

    Manipulating carbon nanotubes (CNTs) through engineering into advanced membranes with superior performance for disinfection and decontamination of water shows great promise but is challenging. In this paper, a facile assembly of CNTs into novel hollow fiber membranes with tunable inner/outer diameters and structures is developed for the first time. These free-standing membranes composed entirely of CNTs feature a porosity of 86±5% and a permeation flux of about 460±50 L m(-2) h(-1) at a pressure differential of 0.04 MPa across the membrane. The randomly oriented interwoven structure of CNTs endows the membranes considerable resistance to pore blockage. Moreover, the adsorption capability of the CNT hollow fiber membranes, which is crucial in the efficient removal of small and trace contaminant molecules, is about 2 orders of magnitude higher than that of commercial polyvinylidene fluoride hollow fiber membranes. The unique advantage of the CNT hollow fiber membranes over other commercial membranes is that they can be in situ electrochemically regenerated after adsorption saturation.

  10. Mechanically enhanced PES electrospun nanofiber membranes (ENMs) for microfiltration: The effects of ENM properties on membrane performance.

    PubMed

    Bae, Jiyeol; Baek, Inchan; Choi, Heechul

    2016-11-15

    The application of electrospun nanofiber membranes (ENMs) as microfilters for the process of water purification requires the substrate to possess suitable strength, permeability, and a smooth surface. Therefore, the fiber homogeneity, inter-fiber adhesion, and surface roughness of the ENMs must be carefully controlled. Concurrently, an understanding of the ENMs' rejection mechanism for contaminants is necessary for the effective application of ENMs. In this study, we demonstrate the fabrication of polyethersulfone (PES) ENMs, which are useful for water purification as water treatment membranes. An optimum fabrication condition that can significantly improve the mechanical property and surface roughness of the PES membrane is also illustrated. This technique induces the solvent remaining on the fiber's surface after the electrospinning process, and the mechanical properties and surface roughness of the membrane are improved by the solvent-induced fusion of the fiber. The fabricated PES ENMs also show higher clean water productivity. Additionally, we show that a particulate contaminant in water is mainly rejected on the ENM surface by using a water filtration test. Based on our conclusions, we suggest the appropriate ENM regeneration method and confirm that the fabricated ENMs show excellent regeneration ability.

  11. Performance of cellulose acetate - polyethersulphone blend membrane prepared using microwave heating for palm oil mill effluent treatment.

    PubMed

    Idris, A; Ahmed, I; Jye, H W

    2007-01-01

    The objective of this research is to investigate the performance of blend cellulose acetate (CA)-polyethersulphone (PES) membranes prepared using microwave heating (MWH) techniques and then compare it with blend CA-PES membranes prepared using conventional heating (CH) methods using bovine serum albumin solution. The superior membranes were then used in the treatment of palm oil mill effluent (POME). Various blends of CA-PES have been blended with PES in the range of 1-5 wt%. This distinctive series of dope formulations of blend CA/PES and pure CA was prepared using N, N-dimethylformamide (DMF) as solvent. The dope solution was prepared by MW heating for 5 min at a high pulse and the membranes were prepared by phase inversion method. The performances of these membranes were evaluated in terms of pure water and permeate flux, percentage removal of total suspended solids (TSS), chemical oxygen demand (COD) and biochemical oxygen demand (BOD). The results indicate that blend membranes prepared using the microwave technique is far more superior compared to that prepared using CH. Blend membranes with 19% CA, 1-3% PES and 80% of DMF solvent were found to be the best membrane formulation.

  12. Preparation, characterization, physical testing and performance of flurocarbon membranes and separators

    NASA Technical Reports Server (NTRS)

    Lagow, R. J.; Dumitru, E. T.

    1983-01-01

    The direct fluorination method of converting carefully selected hydrocarbon substrates to fluorinated membranes was successfully applied to produce promising, novel membranes for electrochemical devices. A family of polymer blends was identified which permits wide latitude in the concentration of both crosslinks and carboxyl groups in hydrocarbon membranes. The membranes of paragraph two were successfully fluorinated.

  13. Potato tuber expression of Arabidopsis WRINKLED1 increase triacylglycerol and membrane lipids while affecting central carbohydrate metabolism.

    PubMed

    Hofvander, Per; Ischebeck, Till; Turesson, Helle; Kushwaha, Sandeep K; Feussner, Ivo; Carlsson, Anders S; Andersson, Mariette

    2016-09-01

    Tuber and root crops virtually exclusively accumulate storage products in the form of carbohydrates. An exception is yellow nutsedge (Cyperus esculentus) in which tubers have the capacity to store starch and triacylglycerols (TAG) in roughly equal amounts. This suggests that a tuber crop can efficiently handle accumulation of energy dense oil. From a nutritional as well as economic aspect, it would be of interest to utilize the high yield capacity of tuber or root crops for oil accumulation similar to yellow nutsedge. The transcription factor WRINKLED1 from Arabidopsis thaliana, which in seed embryos induce fatty acid synthesis, has been shown to be a major factor for oil accumulation. WRINKLED1 was expressed in potato (Solanum tuberosum) tubers to explore whether this factor could impact tuber metabolism. This study shows that a WRINKLED1 transcription factor could induce triacylglycerol accumulation in tubers of transformed potato plants grown in field (up to 12 nmol TAG/mg dry weight, 1% of dry weight) together with a large increase in polar membrane lipids. The changes in metabolism further affected starch accumulation and composition concomitant with massive increases in sugar content.

  14. The outer membrane protein TolC from Sinorhizobium meliloti affects protein secretion, polysaccharide biosynthesis, antimicrobial resistance, and symbiosis.

    PubMed

    Cosme, Ana M; Becker, Anke; Santos, Mário R; Sharypova, Larissa A; Santos, Pedro M; Moreira, Leonilde M

    2008-07-01

    Sinorhizobium meliloti is capable of establishing a symbiotic nitrogen fixation relationship with Medicago sativa. During this process, it must cope with diverse environments and has evolved different types of transport systems that help its propagation in the plant roots. TolC protein family members are the outer-membrane components of several transport systems involved in the export of diverse molecules, playing an important role in bacterial survival. In this work, we have characterized the protein TolC from S. meliloti 2011. An insertional mutation in the tolC gene strongly affected the resistance phenotype to antimicrobial agents and induced higher susceptibility to osmotic and oxidative stresses. Immunodetection experiments and comparison of the extracellular proteins present in the supernatant of the wild-type versus tolC mutant strains showed that the calcium-binding protein ExpE1, the endoglycanase ExsH, and the product of open reading frame SMc04171, a putative hemolysin-type calcium-binding protein, are secreted by a TolC-dependent secretion system. In the absence of TolC, neither succinoglycan nor galactoglucan were detected in the culture supernatant. Moreover, S. meliloti tolC mutant induced a reduced number of nonfixing nitrogen nodules in M. sativa roots. Taken together, our results confirm the importance of TolC in protein secretion, exopolysaccharide biosynthesis, antimicrobials resistance, and symbiosis.

  15. Putative Membrane-Bound Transporters MFSD14A and MFSD14B Are Neuronal and Affected by Nutrient Availability

    PubMed Central

    Lekholm, Emilia; Perland, Emelie; Eriksson, Mikaela M.; Hellsten, Sofie V.; Lindberg, Frida A.; Rostami, Jinar; Fredriksson, Robert

    2017-01-01

    Characterization of orphan transporters is of importance due to their involvement in cellular homeostasis but also in pharmacokinetics and pharmacodynamics. The tissue and cellular localization, as well as function, is still unknown for many of the solute carriers belonging to the major facilitator superfamily (MFS) Pfam clan. Here, we have characterized two putative novel transporters MFSD14A (HIAT1) and MFSD14B (HIATL1) in the mouse central nervous system and found protein staining throughout the adult mouse brain. Both transporters localized to neurons and MFSD14A co-localized with the Golgi marker Giantin in primary embryonic cortex cultures, while MFSD14B staining co-localized with an endoplasmic retention marker, KDEL. Based on phylogenetic clustering analyses, we predict both to have organic substrate profiles, and possible involvement in energy homeostasis. Therefore, we monitored gene regulation changes in mouse embryonic primary cultures after amino acid starvations and found both transporters to be upregulated after 3 h of starvation. Interestingly, in mice subjected to 24 h of food starvation, both transporters were downregulated in the hypothalamus, while Mfsd14a was also downregulated in the brainstem. In addition, in mice fed a high fat diet (HFD), upregulation of both transporters was seen in the striatum. Both MFSD14A and MFSD14B were intracellular neuronal membrane-bound proteins, expressed in the Golgi and Endoplasmic reticulum, affected by both starvation and HFD to varying degree in the mouse brain. PMID:28179877

  16. Factors Affecting the Performance of Hispanic and Non-Hispanic Marine Corps Enlistees

    DTIC Science & Technology

    2015-03-01

    THE PERFORMANCE OF HISPANIC AND NON-HISPANIC MARINE CORPS ENLISTEES by Matthew Curry March 2015 Thesis Advisor: Simona Tick Co-Advisor...March 20 15 Master ’s Thesis 4. TITLE AND SUBTITLE FACTORS AFFECTING THE PERFORMANCE OF HISPANIC AND NON- HISPANIC MARINE CORPS ENLISTEES 6. AUTHOR...S) Matthew Cmw 7. PERFORMING ORGANIZATION NA:i\\tiE(S) AND ADDRESS(ES) Naval Postgraduate School Monterey, CA 93943-5000 9. SPONSORING /MONITORING

  17. Investigation of compressive membrane action in ultra high performance concrete slab strips

    NASA Astrophysics Data System (ADS)

    Foust, Bradley Wade

    Reinforced concrete slabs are found in very common structural systems in both civilian and military applications. The boundary conditions that support the slab play an important role in the response to a particular load. Specifically, the amount of lateral and rotational restraint dictates how a slab responds to a particular load. Compressive membrane (i.e., in-plane) forces are present in slabs when the boundaries are sufficiently stiff, therefore restricting the slab from both lateral translations and rotations. Advancements have been made to account for the additional capacity due to compressive membrane forces in conventional strength concrete. In today's world, concrete performance is improving because of increasing compressive strengths and additional ductility present in concrete members. As a result of this current improvement, there is an urgent need to investigate compressive membrane theory in ultra-high-performance concrete (UHPC) slabs to better understand their behavior. Existing compressive membrane theory should be revisited to determine if current theory is applicable, or if it is not, what modifications should be made. This study will provide insight into the validity of existing theory that is currently used to predict the ultimate capacity in conventional-strength concrete slabs and attempt to modify the existing equations to account for high-strength concrete materials. A matrix of 14 normal-strength concrete (NSC) and 13 UHPC slabs was tested both statically and dynamically to better understand the behavior of each material set and the effects that boundary conditions have on slab response. The results from these experiments were then compared to response calculations made from existing theory as well as finite element analyses. Valuable data sets on rigidly restrained UHPC slab response were obtained through an experimental research program. The experiments helped to validate the associated numerical analysis that was performed. It was

  18. Size, but not experience, affects the ontogeny of constriction performance in ball pythons (Python regius).

    PubMed

    Penning, David A; Dartez, Schuyler F

    2016-03-01

    Constriction is a prey-immobilization technique used by many snakes and is hypothesized to have been important to the evolution and diversification of snakes. However, very few studies have examined the factors that affect constriction performance. We investigated constriction performance in ball pythons (Python regius) by evaluating how peak constriction pressure is affected by snake size, sex, and experience. In one experiment, we tested the ontogenetic scaling of constriction performance and found that snake diameter was the only significant factor determining peak constriction pressure. The number of loops applied in a coil and its interaction with snake diameter did not significantly affect constriction performance. Constriction performance in ball pythons scaled differently than in other snakes that have been studied, and medium to large ball pythons are capable of exerting significantly higher pressures than those shown to cause circulatory arrest in prey. In a second experiment, we tested the effects of experience on constriction performance in hatchling ball pythons over 10 feeding events. By allowing snakes in one test group to gain constriction experience, and manually feeding snakes under sedation in another test group, we showed that experience did not affect constriction performance. During their final (10th) feedings, all pythons constricted similarly and with sufficiently high pressures to kill prey rapidly. At the end of the 10 feeding trials, snakes that were allowed to constrict were significantly smaller than their non-constricting counterparts.

  19. Analytical Investigation and Improvement of Performance of a Proton Exchange Membrane (Pem) Fuel Cell in Mobile Applications

    NASA Astrophysics Data System (ADS)

    Khazaee, I.

    2015-05-01

    In this study, the performance of a proton exchange membrane fuel cell in mobile applications is investigated analytically. At present the main use and advantages of fuel cells impact particularly strongly on mobile applications such as vehicles, mobile computers and mobile telephones. Some external parameters such as the cell temperature (Tcell ) , operating pressure of gases (P) and air stoichiometry (λair ) affect the performance and voltage losses in the PEM fuel cell. Because of the existence of many theoretical, empirical and semi-empirical models of the PEM fuel cell, it is necessary to compare the accuracy of these models. But theoretical models that are obtained from thermodynamic and electrochemical approach, are very exact but complex, so it would be easier to use the empirical and smi-empirical models in order to forecast the fuel cell system performance in many applications such as mobile applications. The main purpose of this study is to obtain the semi-empirical relation of a PEM fuel cell with the least voltage losses. Also, the results are compared with the existing experimental results in the literature and a good agreement is seen.

  20. Effect of relative humidity cycles accompanied by intermittent start/stop switches on performance degradation of membrane electrode assembly components in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Qiu, Yanling; Zhong, Hexiang; Wang, Meiri; Zhang, Huamin

    2015-06-01

    The performance degradation of membrane electrode assembly (MEA) components in proton exchange membrane fuel cell (PEMFC) is studied by designing relative humidity (RH) cycles accompanied by intermittent start/stop switches. Cathode catalyst activity, permeability and resistance of proton exchange membrane (PEM) as well as cell performance are monitored during the test procedure. The interfaces of MEA, the catalyst particle distribution near the cathode inlet are characterized by SEM and TEM, respectively. The results demonstrate both the overall H2 permeability and crossover current of PEM are doubled compared with its initial properties. Signs of PEM degradation, including periodical thinning, cracks and pinholes formation, are observed after 300 RH cycles and 40 times of start/stop switches. The average Pt particle size increases by more than 75%, and the cathode electrochemical surface area decreases by 48% after the test procedure. Meanwhile, the cathode catalyst layer becomes looser due to the dissolution of some smaller Pt particles and catalyst agglomeration in the RH cycles and the high potential during the intermittent start/stop switches. The membrane resistance demonstrates downshift variation during the RH cycles. PEMFC performance, however, decays due to the chemical and electrochemical attack as well as the mechanical stresses.

  1. High-performance multi-functional reverse osmosis membranes obtained by carbon nanotube·polyamide nanocomposite

    PubMed Central

    Inukai, Shigeki; Cruz-Silva, Rodolfo; Ortiz-Medina, Josue; Morelos-Gomez, Aaron; Takeuchi, Kenji; Hayashi, Takuya; Tanioka, Akihiko; Araki, Takumi; Tejima, Syogo; Noguchi, Toru; Terrones, Mauricio; Endo, Morinobu

    2015-01-01

    Clean water obtained by desalinating sea water or by purifying wastewater, constitutes a major technological objective in the so-called water century. In this work, a high-performance reverse osmosis (RO) composite thin membrane using multi-walled carbon nanotubes (MWCNT) and aromatic polyamide (PA), was successfully prepared by interfacial polymerization. The effect of MWCNT on the chlorine resistance, antifouling and desalination performances of the nanocomposite membranes were studied. We found that a suitable amount of MWCNT in PA, 15.5 wt.%, not only improves the membrane performance in terms of flow and antifouling, but also inhibits the chlorine degradation on these membranes. Therefore, the present results clearly establish a solid foundation towards more efficient large-scale water desalination and other water treatment processes. PMID:26333385

  2. High-performance multi-functional reverse osmosis membranes obtained by carbon nanotube·polyamide nanocomposite.

    PubMed

    Inukai, Shigeki; Cruz-Silva, Rodolfo; Ortiz-Medina, Josue; Morelos-Gomez, Aaron; Takeuchi, Kenji; Hayashi, Takuya; Tanioka, Akihiko; Araki, Takumi; Tejima, Syogo; Noguchi, Toru; Terrones, Mauricio; Endo, Morinobu

    2015-09-03

    Clean water obtained by desalinating sea water or by purifying wastewater, constitutes a major technological objective in the so-called water century. In this work, a high-performance reverse osmosis (RO) composite thin membrane using multi-walled carbon nanotubes (MWCNT) and aromatic polyamide (PA), was successfully prepared by interfacial polymerization. The effect of MWCNT on the chlorine resistance, antifouling and desalination performances of the nanocomposite membranes were studied. We found that a suitable amount of MWCNT in PA, 15.5 wt.%, not only improves the membrane performance in terms of flow and antifouling, but also inhibits the chlorine degradation on these membranes. Therefore, the present results clearly establish a solid foundation towards more efficient large-scale water desalination and other water treatment processes.

  3. High-performance multi-functional reverse osmosis membranes obtained by carbon nanotube·polyamide nanocomposite

    NASA Astrophysics Data System (ADS)

    Inukai, Shigeki; Cruz-Silva, Rodolfo; Ortiz-Medina, Josue; Morelos-Gomez, Aaron; Takeuchi, Kenji; Hayashi, Takuya; Tanioka, Akihiko; Araki, Takumi; Tejima, Syogo; Noguchi, Toru; Terrones, Mauricio; Endo, Morinobu

    2015-09-01

    Clean water obtained by desalinating sea water or by purifying wastewater, constitutes a major technological objective in the so-called water century. In this work, a high-performance reverse osmosis (RO) composite thin membrane using multi-walled carbon nanotubes (MWCNT) and aromatic polyamide (PA), was successfully prepared by interfacial polymerization. The effect of MWCNT on the chlorine resistance, antifouling and desalination performances of the nanocomposite membranes were studied. We found that a suitable amount of MWCNT in PA, 15.5 wt.%, not only improves the membrane performance in terms of flow and antifouling, but also inhibits the chlorine degradation on these membranes. Therefore, the present results clearly establish a solid foundation towards more efficient large-scale water desalination and other water treatment processes.

  4. Performance improvement of proton exchange membrane fuel cell by using annular shaped geometry

    NASA Astrophysics Data System (ADS)

    Khazaee, I.; Ghazikhani, M.

    2011-03-01

    A complete three-dimensional and single phase CFD model for a different geometry of proton exchange membrane (PEM) fuel cell is used to investigate the effect of using different connections between bipolar plate and gas diffusion layer on the performances, current density and gas concentration. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components. This computational fluid dynamics code is used as the direct problem solver, which is used to simulate the three-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC that cannot be investigated experimentally. The results show that the predicted polarization curves by using this model are in good agreement with the experimental results. Also the results show that by increasing the number of connection between GDL and bipolar plate the performance of the fuel cell enhances.

  5. Causal attribution and affective response as mediated by task performance and self-acceptance.

    PubMed

    Green, T D; Bailey, R C; Zinser, O; Williams, D E

    1994-12-01

    Predictions derived from cognitive consistency theories, self-esteem theories, and ego-serving-bias theory concerning how students would make attributional and affective responses to their academic performance were investigated. 202 university students completed a measure of self-acceptance of their college ability and made attributional and affective responses to an hypothetical examination performance. Analyses showed that students receiving positive feedback perceived greater internal causality and responded with greater positive affect than students receiving negative feedback. Self-acceptance did not moderate the attributions or affective reactions. The results supported the ego-serving-bias theory and provided partial support for self-esteem theory. Findings did not support predictions from cognitive-consistency theory.

  6. System performance and cost sensitivity comparisons of stretched membrane heliostat reflectors with current generation glass/metal concepts

    SciTech Connect

    Murphy, L.M.; Anderson, J.V.; Short, W.; Wendelin, T.

    1985-12-01

    Heliostat costs have long been recognized as a major factor in the cost of solar central receiver plants. Research on stretched membrane heliostats has been emphasized because of their potential as a cost-effective alternative to current glass/metal designs. However, the cost and performance potential of stretched membrane heliostats from a system perspective has not been studied until this time. The optical performance of individual heliostats is predicted here using results established in previous structural studies. These performance predictions are used to compare both focused and unfocused stretched membrane heliostats with state-of-the-art glass/metal heliostats from a systems perspective. We investigated the sensitivity of the relative cost and performance of fields of heliostats to a large number of parameter variations, including system size, delivery temperature, heliostat module size, surface specularity, hemispherical reflectance, and macroscopic surface quality. The results indicate that focused stretched membrane systems should have comparable performance levels to those of current glass/metal heliostat systems. Further, because of their relatively lower cost, stretched membrane heliostats should provide an economically attractive alternative to current glass/metal heliostats over essentially the entire range of design parameters studied. Unfocused stretched membrane heliostats may also be attractive for a somewhat more limited range of applications, including the larger plant sizes and lower delivery temperatures.

  7. Biological Fuel Cells and Membranes.

    PubMed

    Ghassemi, Zahra; Slaughter, Gymama

    2017-01-17

    Biofuel cells have been widely used to generate bioelectricity. Early biofuel cells employ a semi-permeable membrane to separate the anodic and cathodic compartments. The impact of different membrane materials and compositions has also been explored. Some membrane materials are employed strictly as membrane separators, while some have gained significant attention in the immobilization of enzymes or microorganisms within or behind the membrane at the electrode surface. The membrane material affects the transfer rate of the chemical species (e.g., fuel, oxygen molecules, and products) involved in the chemical reaction, which in turn has an impact on the performance of the biofuel cell. For enzymatic biofuel cells, Nafion, modified Nafion, and chitosan membranes have been used widely and continue to hold great promise in the long-term stability of enzymes and microorganisms encapsulated within them. This article provides a review of the most widely used membrane materials in the development of enzymatic and microbial biofuel cells.

  8. Biological Fuel Cells and Membranes

    PubMed Central

    Ghassemi, Zahra; Slaughter, Gymama

    2017-01-01

    Biofuel cells have been widely used to generate bioelectricity. Early biofuel cells employ a semi-permeable membrane to separate the anodic and cathodic compartments. The impact of different membrane materials and compositions has also been explored. Some membrane materials are employed strictly as membrane separators, while some have gained significant attention in the immobilization of enzymes or microorganisms within or behind the membrane at the electrode surface. The membrane material affects the transfer rate of the chemical species (e.g., fuel, oxygen molecules, and products) involved in the chemical reaction, which in turn has an impact on the performance of the biofuel cell. For enzymatic biofuel cells, Nafion, modified Nafion, and chitosan membranes have been used widely and continue to hold great promise in the long-term stability of enzymes and microorganisms encapsulated within them. This article provides a review of the most widely used membrane materials in the development of enzymatic and microbial biofuel cells. PMID:28106711

  9. Diversification of the AlpB Outer Membrane Protein of Helicobacter pylori Affects Biofilm Formation and Cellular Adhesion

    PubMed Central

    Osaki, Takako; Fukutomi, Toshiyuki; Hanawa, Tomoko; Kurata, Satoshi; Zaman, Cynthia; Hojo, Fuhito; Kamiya, Shigeru

    2016-01-01

    ABSTRACT Helicobacter pylori is one of the most common causes of bacterial infection in humans, and it forms biofilms on human gastric mucosal epithelium as well as on in vitro abiotic surfaces. Bacterial biofilm is critical not only for environmental survival but also for successful infection. We previously demonstrated that strain TK1402, which was isolated from a Japanese patient with duodenal and gastric ulcers, has high biofilm-forming ability in vitro relative to other strains. In addition, we showed that outer membrane vesicles (OMV) play an important role in biofilm formation. The aim of this study was to analyze which protein(s) in the OMV contributes to biofilm formation in TK1402. We obtained a spontaneous mutant strain derived from TK1402 lacking biofilm-forming ability. The protein profiles of the OMV were compared between this mutant strain and the wild type, and it was found that AlpB, an outer membrane protein in the OMV of the mutant strain, was markedly decreased compared to that of the wild type. Restoration of TK1402 alpB to the mutant strain fully recovered the ability to form biofilm. However, restoration with alpB from other strains demonstrated incomplete recovery of biofilm-forming ability. We therefore inferred that the variable region of AlpB (amino acid positions 121 to 146) was involved in TK1402 biofilm formation. In addition, diversification of the AlpB sequence was shown to affect the ability to adhere to AGS cells. These results demonstrate a new insight into the molecular mechanisms of host colonization by H. pylori. IMPORTANCE Bacterial biofilm is critical not only for environmental survival but also for successful infection. The mechanism of Helicobacter pylori adherence to host cells mediated by cell surface adhesins has been the focus of many studies, but little is known regarding factors involved in H. pylori biofilm formation. Our study demonstrated that AlpB plays an important role in biofilm formation and that this property

  10. Diversification of the AlpB Outer Membrane Protein of Helicobacter pylori Affects Biofilm Formation and Cellular Adhesion.

    PubMed

    Yonezawa, Hideo; Osaki, Takako; Fukutomi, Toshiyuki; Hanawa, Tomoko; Kurata, Satoshi; Zaman, Cynthia; Hojo, Fuhito; Kamiya, Shigeru

    2017-03-15

    Helicobacter pylori is one of the most common causes of bacterial infection in humans, and it forms biofilms on human gastric mucosal epithelium as well as on in vitro abiotic surfaces. Bacterial biofilm is critical not only for environmental survival but also for successful infection. We previously demonstrated that strain TK1402, which was isolated from a Japanese patient with duodenal and gastric ulcers, has high biofilm-forming ability in vitro relative to other strains. In addition, we showed that outer membrane vesicles (OMV) play an important role in biofilm formation. The aim of this study was to analyze which protein(s) in the OMV contributes to biofilm formation in TK1402. We obtained a spontaneous mutant strain derived from TK1402 lacking biofilm-forming ability. The protein profiles of the OMV were compared between this mutant strain and the wild type, and it was found that AlpB, an outer membrane protein in the OMV of the mutant strain, was markedly decreased compared to that of the wild type. Restoration of TK1402 alpB to the mutant strain fully recovered the ability to form biofilm. However, restoration with alpB from other strains demonstrated incomplete recovery of biofilm-forming ability. We therefore inferred that the variable region of AlpB (amino acid positions 121 to 146) was involved in TK1402 biofilm formation. In addition, diversification of the AlpB sequence was shown to affect the ability to adhere to AGS cells. These results demonstrate a new insight into the molecular mechanisms of host colonization by H. pyloriIMPORTANCE Bacterial biofilm is critical not only for environmental survival but also for successful infection. The mechanism of Helicobacter pylori adherence to host cells mediated by cell surface adhesins has been the focus of many studies, but little is known regarding factors involved in H. pylori biofilm formation. Our study demonstrated that AlpB plays an important role in biofilm formation and that this property depends

  11. Improvement of hydrophobic integral membrane protein identification by mild performic acid oxidation-assisted digestion.

    PubMed

    Cao, Rui; Liu, Yisong; Chen, Ping; Lv, Rong; Song, Qin; Sheng, Tingting; He, Quanyuan; Wang, Yin; Wang, Xianchun; Liang, Songping

    2010-12-15

    Integral membrane proteins (IMPs) are critical for the maintenance of biological systems and represent important targets for the treatment of disease. The hydrophobicity and low abundance of IMPs make them difficult to analyze. In proteomic analyses, hydrophobic peptides including transmembrane domains are often underrepresented, and this reduces the sequence coverage and reliability of the identified IMPs. Here we report a new strategy, mild performic acid oxidation treatment (mPAOT), for improvement of IMP identification. In the mPAOT strategy, the hydrophobicity of IMPs is significantly decreased by oxidizing their methionine and cysteine residues with performic acid, thereby improving the solubility and enzymolysis of these proteins. The application of the mPAOT strategy to the analysis of IMPs from human nasopharyngeal carcinoma CNE1 cell line demonstrated that many IMPs, including those with high hydrophobicity, could be reliably identified.

  12. Effect of operating conditions on the performances of multichannel ceramic UF membranes for textile mercerization wastewater treatment.

    PubMed

    Zebić Avdičević, Maja; Košutić, Krešimir; Dobrović, Slaven

    2017-01-01

    Textile wastewaters are rated as one of the most polluting in all industrial sectors, and membrane separation is the most promising technology for their treatment and reuse of auxiliary chemicals. This study evaluates the performance of three types of tubular ceramic ultrafiltration membranes differing by mean pore size (1, 2 and 500 kDa) treating textile mercerization wastewater from a textile mill at different operating conditions: cross-flow velocity (CFV) and temperature. Acceptable results were obtained with 1 kDa ceramic membrane, with rejection efficiencies 92% for suspended solids, 98% for turbidity, 98% for color and 53% for total organic carbon at 20°C and 3 m s(-1) CFV. Highest fouling effect was observed for 500 kDa membrane and lowest CFV. According to the observed results, 1 kDa membrane could be used for the treatment of wastewater from the textile mercerization process in terms of permeate quality.

  13. A high performance membrane for sorption and pervaporation separation of ethyl tert-butyl ether and ethanol mixtures

    SciTech Connect

    Luo, G.S.; Niang, M.; Schaetzel, P.

    1999-02-01

    A new kind of membrane was prepared by blending 5 wt% poly(1-vinylpyrrolidone-co-acrylic acid) with cellulose acetate propionate for the separation of ethyl tert-butyl ether and ethanol mixtures. The membrane properties were evaluated by pervaporation and sorption of mixtures of ethyl tert-butyl ether/ethanol. The experimental results show that the selectivity and the fluxes of this membrane depend upon the feed composition and upon the temperature. The minimum values of ethanol concentration in the permeate and in the sorption solution were obtained in the vicinity of the azeotropic point. Compared with the pure CAP membrane, the new membrane shows high performance for the separation of ETBE and EtOH mixtures, especially under high temperature conditions.

  14. Performance of a submerged anaerobic membrane bioreactor with forward osmosis membrane for low-strength wastewater treatment.

    PubMed

    Chen, Lin; Gu, Yangshuo; Cao, Chuqing; Zhang, Jun; Ng, Jing-Wen; Tang, Chuyang

    2014-03-01

    A submerged anaerobic membrane bioreactor with forward osmosis membrane (FO-AnMBR) was operated at 25 °C for the treatment of synthetic wastewater. As the experiment progressed, the water flux reduced due to the membrane fouling and the increasing salinity in the reactor, and achieved at around 3.5 LMH in one cycle. It was worth noting that the level of salinity in the reactor was not a concern in terms of inhibition or toxic effects on the biological processes. The FO-AnMBR process exhibited greater than 96% removal of organic carbon, nearly 100% of total phosphorus and 62% of ammonia-nitrogen, respectively, suggesting a better removal efficiency than the conventional anaerobic membrane bioreactor. The methane and carbon dioxide compositions achieved concentrations of around 65%-78% and 22%-35%, respectively; and no obvious difference in the biogas composition was observed with the changes of conductivity. With respect to the methane yield, an average value of 0.21 L CH4 g(-1) COD was obtained, exhibiting the feasibility of energy recovery by this FO-AnMBR system. Additionally, an increase in the salinity enhanced the accumulation of soluble microbial products, especially for the proteins with 88.9% increment as the conductivity increased from 1.2 to 17.3 ms cm(-1). In contrast, a relatively stable concentration of extracellular polymer substances (EPS) was observed, indicating that the influence of conductivity on EPS cannot be directly correlated.

  15. An Evaluation of the Performance and Economics of Membranes and Separators in Single Chamber Microbial Fuel Cells Treating Domestic Wastewater

    PubMed Central

    Christgen, Beate; Scott, Keith; Dolfing, Jan; Head, Ian M.; Curtis, Thomas P.

    2015-01-01

    The cost of materials is one of the biggest barriers for wastewater driven microbial fuel cells (MFCs). Many studies use expensive materials with idealistic wastes. Realistically the choice of an ion selective membrane or nonspecific separators must be made in the context of the cost and performance of materials available. Fourteen membranes and separators were characterized for durability, oxygen diffusion and ionic resistance to enable informed membrane selection for reactor tests. Subsequently MFCs were operated in a cost efficient reactor design using Nafion, ethylene tetrafluoroethylene (ETFE) or polyvinylidene fluoride (PVDF) membranes, a nonspecific separator (Rhinohide), and a no-membrane design with a carbon-paper internal gas diffusion cathode. Peak power densities during polarisation, from MFCs using no-membrane, Nafion and ETFE, reached 67, 61 and 59 mWm-2, and coulombic efficiencies of 68±11%, 71±12% and 92±6%, respectively. Under 1000Ω, Nafion and ETFE achieved an average power density of 29 mWm-2 compared to 24 mWm-2 for the membrane-less reactors. Over a hypothetical lifetime of 10 years the generated energy (1 to 2.5 kWhm-2) would not be sufficient to offset the costs of any membrane and separator tested. PMID:26305330

  16. Fine-Tuning the Surface of Forward Osmosis Membranes via Grafting Graphene Oxide: Performance Patterns and Biofouling Propensity.

    PubMed

    Hegab, Hanaa M; ElMekawy, Ahmed; Barclay, Thomas G; Michelmore, Andrew; Zou, Linda; Saint, Christopher P; Ginic-Markovic, Milena

    2015-08-19

    Graphene oxide (GO) nanosheets were attached to the polyamide selective layer of thin film composite (TFC) forward osmosis (FO) membranes through a poly L-Lysine (PLL) intermediary using either layer-by-layer or hybrid (H) grafting strategies. Fourier transform infrared spectroscopy, zeta potential, and thermogravimetric analysis confirmed the successful attachment of GO/PLL, the surface modification enhancing both the hydrophilicity and smoothness of the membrane's surface demonstrated by water contact angle, atomic force microscopy, and transmission electron microscopy. The biofouling resistance of the FO membranes determined using an adenosine triphosphate bioluminescence test showed a 99% reduction in surviving bacteria for GO/PLL-H modified membranes compared to pristine membrane. This antibiofouling property of the GO/PLL-H modified membrane was reflected in reduced flux decline compared to all other samples when filtering brackish water under biofouling conditions. Further, the high density and tightly bound GO nanosheets using the hybrid modification reduced the reverse solute flux compared to the pristine, which reflects improved membrane selectivity. These results illustrate that the GO/PLL-H modification is a valuable addition to improve the performance of FO TFC membranes.

  17. Performance of fuel cell using calcium phosphate hydrogel membrane prepared from waste incineration fly ash and chicken bone powder.

    PubMed

    Fukui, Kunihiro; Arimitsu, Naoki; Jikihara, Kenji; Yamamoto, Tetsuya; Yoshida, Hideto

    2009-09-15

    Waste incineration fly ash and bone powder could be successfully recycled to calcium phosphate hydrogel, a type of fast proton conductor. The electric conductivity of the crystallized hydrogel from them was compared with that from calcium carbonate reagent. It was found that the conductivity of the hydrogel from bone powder is almost equal to that from calcium carbonate reagent, which is higher than that from incineration fly ash. Because the crystallized hydrogel from incineration ash has a lower crystallinity than that from bone powder and calcium carbonate reagent. However, the difference of the conductivity among them can be hardly observed above 100 degrees C. The fuel cell with membrane electrode assembly (MEA) using the calcium phosphate hydrogel membrane prepared from incineration fly ash and bone powder was observed to generate electricity. The performance of fuel cells having the hydrogel membrane obtained from all raw materials increases with the cell temperature, and the fuel cell containing the hydrogel membrane from incineration fly ash has the highest dependence of the fuel cell performance. For this reason, the difference in the cell performance among them can be hardly observed above 120 degrees C. This tendency agrees with the change in the electric conductivity with the temperature. Further, the performance of all fuel cells with the hydrogel membrane is superior to that of the fuel cell with perfluorosulfonic polymer membrane at temperatures greater than approximately 85 degrees C.

  18. Use of mechanistic carbon corrosion model to predict performance loss in Polymer Electrolyte Membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Dhanushkodi, S. R.; Kundu, S.; Fowler, M. W.; Pritzker, M. D.

    2014-12-01

    A membrane electrode assembly is subjected to carbon corrosion accelerated stress tests (ASTs) involving the application of square-wave voltage cycles with different upper limits to measure the resulting loss in the mass of the carbon support at the cathode catalyst layer (CL) and the associated degradation in performance. Carbon loss is determined from the amount of CO2 evolved during degradation, while the performance loss is measured from the reduction in the cell voltage at 1.5 A cm-2 relative to the performance obtained in its beginning-of-life state. A kinetic model for carbon corrosion describing the rate of evolution of CO2 is shown to accurately predict the carbon loss measured during the various carbon corrosion ASTs in this study. A plot of the performance losses from the various carbon corrosion ASTs versus the corresponding carbon losses reveals that all the data demonstrate consistent degradation regardless of the AST conditions, and these result can be fitted with an exponential function termed the 'fingerprint' expression. By combining the carbon corrosion model and fingerprint expression, both the carbon loss and performance loss of a cathode CL during a carbon corrosion AST can be accurately predicted based only on knowledge of the waveform of the input voltage.

  19. Tail autotomy affects bipedalism but not sprint performance in a cursorial Mediterranean lizard

    NASA Astrophysics Data System (ADS)

    Savvides, Pantelis; Stavrou, Maria; Pafilis, Panayiotis; Sfenthourakis, Spyros

    2017-02-01

    Running is essential in all terrestrial animals mainly for finding food and mates and escaping from predators. Lizards employ running in all their everyday functions, among which defense stands out. Besides flight, tail autotomy is another very common antipredatory strategy within most lizard families. The impact of tail loss to sprint performance seems to be species dependent. In some lizard species, tail shedding reduces sprint speed, in other species, increases it, and, in a few species, speed is not affected at all. Here, we aimed to clarify the effect of tail autotomy on the sprint performance of a cursorial lizard with particular adaptations for running, such as bipedalism and spike-like protruding scales (fringes) on the toepads that allow high speed on sandy substrates. We hypothesized that individuals that performed bipedalism, and have more and larger fringes, would achieve higher sprint performance. We also anticipated that tail shedding would affect sprint speed (though we were not able to define in what way because of the unpredictable effects that tail loss has on different species). According to our results, individuals that ran bipedally were faster; limb length and fringe size had limited effects on sprint performance whereas tail autotomy affected quadrupedal running only in females. Nonetheless, tail loss significantly affected bipedalism: the ability for running on hindlimbs was completely lost in all adult individuals and in 72.3% of juveniles.

  20. Tail autotomy affects bipedalism but not sprint performance in a cursorial Mediterranean lizard.

    PubMed

    Savvides, Pantelis; Stavrou, Maria; Pafilis, Panayiotis; Sfenthourakis, Spyros

    2017-02-01

    Running is essential in all terrestrial animals mainly for finding food and mates and escaping from predators. Lizards employ running in all their everyday functions, among which defense stands out. Besides flight, tail autotomy is another very common antipredatory strategy within most lizard families. The impact of tail loss to sprint performance seems to be species dependent. In some lizard species, tail shedding reduces sprint speed, in other species, increases it, and, in a few species, speed is not affected at all. Here, we aimed to clarify the effect of tail autotomy on the sprint performance of a cursorial lizard with particular adaptations for running, such as bipedalism and spike-like protruding scales (fringes) on the toepads that allow high speed on sandy substrates. We hypothesized that individuals that performed bipedalism, and have more and larger fringes, would achieve higher sprint performance. We also anticipated that tail shedding would affect sprint speed (though we were not able to define in what way because of the unpredictable effects that tail loss has on different species). According to our results, individuals that ran bipedally were faster; limb length and fringe size had limited effects on sprint performance whereas tail autotomy affected quadrupedal running only in females. Nonetheless, tail loss significantly affected bipedalism: the ability for running on hindlimbs was completely lost in all adult individuals and in 72.3% of juveniles.

  1. Ankyrin and band 3 differentially affect expression of membrane glycoproteins but are not required for erythroblast enucleation.

    PubMed

    Ji, Peng; Lodish, Harvey F

    2012-01-27

    During late stages of mammalian erythropoiesis the nucleus undergoes chromatin condensation, migration to the plasma membrane, and extrusion from the cytoplasm surrounded by a segment of plasma membrane. Since nuclear condensation occurs in all vertebrates, mammalian erythroid membrane and cytoskeleton proteins were implicated as playing important roles in mediating the movement and extrusion of the nucleus. Here we use erythroid ankyrin deficient and band 3 knockout mouse models to show that band 3, but not ankyrin, plays an important role in regulating the level of erythroid cell membrane proteins, as evidenced by decreased cell surface expression of glycophorin A in band 3 knockout mice. However, neither band 3 nor ankyrin are required for enucleation. These results demonstrate that mammalian erythroblast enucleation does not depend on the membrane integrity generated by the ankyrin-band 3 complex.

  2. Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

    PubMed

    Cheng, Zhi-Lin; Han, Shuai

    2016-01-01

    A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment.

  3. Novel proton exchange membrane fuel cell electrodes to improve performance of reversible fuel cell systems

    NASA Astrophysics Data System (ADS)

    Brown, Tim Matthew

    Proton exchange membrane (PEM) fuel cells react fuel and oxidant to directly and efficiently produce electrical power, without the need for combustion, heat engines, or motor-generators. Additionally, PEM fuel cell systems emit zero to virtually zero criteria pollutants and have the ability to reduce CO2 emissions due to their efficient operation, including the production or processing of fuel. A reversible fuel cell (RFC) is one particular application for a PEM fuel cell. In this application the fuel cell is coupled with an electrolyzer and a hydrogen storage tank to complete a system that can store and release electrical energy. These devices can be highly tailored to specific energy storage applications, potentially surpassing the performance of current and future secondary battery technology. Like all PEM applications, RFCs currently suffer from performance and cost limitations. One approach to address these limitations is to improve the cathode performance by engineering more optimal catalyst layer geometry as compared to the microscopically random structure traditionally used. Ideal configurations are examined and computer modeling shows promising performance improvements are possible. Several novel manufacturing methods are used to build and test small PEM fuel cells with novel electrodes. Additionally, a complete, dynamic model of an RFC system is constructed and the performance is simulated using both traditional and novel cathode structures. This work concludes that PEM fuel cell microstructures can be tailored to optimize performance based on design operating conditions. Computer modeling results indicate that novel electrode microstructures can improve fuel cell performance, while experimental results show similar performance gains that bolster the theoretical predictions. A dynamic system model predicts that novel PEM fuel cell electrode structures may enable RFC systems to be more competitive with traditional energy storage technology options.

  4. Improving the performance of an aerobic membrane bioreactor (MBR) treating pharmaceutical wastewater with powdered activated carbon (PAC) addition.

    PubMed

    Kaya, Yasemin; Bacaksiz, A Murat; Golebatmaz, Ugur; Vergili, Ilda; Gönder, Z Beril; Yilmaz, Gulsum

    2016-04-01

    In this study, the effects of organic loading rate (OLR) and the addition of powdered activated carbon (PAC) on the performance and membrane fouling of MBR were conducted to treat real pharmaceutical process wastewater. Over 145 days of operation, the MBR system was operated at OLRs ranging from 1 to 2 kg COD m(-3) day(-1) without sludge wasting. The addition of PAC provided an improvement in the flux, despite an increase in the OLR:PAC ratio. The results demonstrated that the hybrid PAC-MBR system maintained a reduced amount of membrane fouling and steadily increased the removal performance of etodolac. PAC addition reduced the deposition of extracellular polymeric substance and organic matter on the membrane surface and resulted an increase in COD removal even at higher OLRs with low PAC addition. Membrane fouling mechanisms were investigated using combined adsorption fouling models. Modified fouling index values and normalized mass transfer coefficient values indicated that predominant fouling mechanism was cake adsorption.

  5. Superhydrophobic and superhydrophilic surface-enhanced separation performance of porous inorganic membranes for biomass-to-biofuel conversion applications

    SciTech Connect

    Hu, Michael Z.; Engtrakul, Chaiwat; Bischoff, Brian L.; Jang, Gyoung G.; Theiss, Timothy J.; Davis, Mark F.

    2016-11-14

    A new class of porous membranes is introduced to provide unique separation mechanisms by surface interactions and capillary condensation. High-performance architectural surface selective (HiPAS) membranes were designed for high perm-selective flux and high-temperature tolerance for hot vapor processing and liquid processing Due to surface-enhanced selectivity, larger-fluxes were achieved by utilizing larger pore sizes (~8 nm for vapor phase and micron-sized pores for liquid phase separations). This paper describes a membrane-based separation concept for biomass conversion pathways and demonstrates the initial data for selective permeation of toluene-water and toluene-phenol-water relevant to biofuel processing.

  6. Malaysian and Singaporean students' affective characteristics and mathematics performance: evidence from PISA 2012.

    PubMed

    Thien, Lei Mee; Ong, Mei Yean

    2015-01-01

    This paper attempts to identify the extent to which the affective characteristics of Malaysian and Singaporean students' attainment compared to the OECD average in Programme for International Student Assessment (PISA) 2012, and examine the influence of students' affective characteristics, gender, and their socioeconomic status on mathematics performance at both student and school levels. Sample consisted of 5197 and 5546 15-year-old Malaysian and Singaporean students. Data were analysed using hierarchical linear modelling approach with HLM 7.0 software. Results showed that the Index of economic, social, and cultural status (ESCS), mathematics self-efficacy, and mathematics anxiety have significant effects on mathematics performance in Malaysia and Singapore at the student level. Proportion of boys at the school level has no significant effects on mathematics performance for both Malaysian and Singaporean students. ESCS mean at the school level has positive and significant effects on mathematics performance in Malaysia, but not in Singapore. Limitations, implications, and future studies were discussed.

  7. Performances of anaerobic and aerobic membrane bioreactors for the treatment of synthetic textile wastewater.

    PubMed

    Yurtsever, Adem; Sahinkaya, Erkan; Aktaş, Özgür; Uçar, Deniz; Çınar, Özer; Wang, Zhiwei

    2015-09-01

    This study aims at comparatively evaluating anaerobic and aerobic MBRs for the treatment of azo-dye containing synthetic wastewater. Also, the filtration performances of AnMBR and AeMBR were compared under similar operating conditions. In both MBRs, high COD removal efficiencies were observed. Although almost complete color removal was observed in AnMBR, only partial (30-50%) color removal was achieved in AeMBR. AnMBR was successfully operated up to 9 L/(m(2)h) (LMH) and no chemical cleaning was required at 4.5 LMH for around 50 days. AeMBR was operated successfully up to 20 LMH. The filtration resistance of AnMBR was generally higher compared to AeMBR although reversible fouling rates were comparable. In both MBRs, offline chemical cleaning with NaOCl and sulfuric acid almost completely removed irreversible fouling and the resistances of chemically cleaned membranes were close to those of new membranes.

  8. Performance of hydrophobic interaction ligands for human membrane-bound catechol-O-methyltransferase purification.

    PubMed

    Santos, Fátima Milhano; Pedro, Augusto Quaresma; Soares, Rui Filipe; Martins, Rita; Bonifácio, Maria João; Queiroz, João António; Passarinha, Luís António

    2013-06-01

    Despite of membrane catechol-O-methyltransferase (MBCOMT, EC 2.1.1.6) physiological importance on catecholamines' O-methylation, no studies allowed their total isolation. Therefore, for the first time, we compare the performance of three hydrophobic adsorbents (butyl-, epoxy-, and octyl-Sepharose) in purification of recombinant human COMT (hMBCOMT) from crude Brevibacillus choshinensis cell lysates to develop a sustainable chromatographic process. Hydrophobic matrices were evaluated in terms of selectivity and hMBCOMT's binding and elution conditions. Results show that hMBCOMT's adsorption was promoted on octyl and butyl at ≤375 mM NaH2 PO4, while on epoxy higher concentrations (>850 mM) were required. Additionally, hMBCOMT's elution was promoted on epoxy, butyl, and octyl using respectively 0.1-0.5, 0.25-1, and 1% of Triton X-100. On butyl media, a stepwise strategy using 375 and 0 mM NaH2PO4, followed by three elution steps at 0.25, 0.7 and 1% Triton X-100, allowed selective hMBCOMT isolation. In conclusion, significant amounts of MBCOMT were purified with high selectivity on a single chromatography procedure, despite its elution occurs on multiple peaks. Although successful applications of hydrophobic interaction chromatography in purification of membrane proteins are uncommon, we proved that traditional hydrophobic matrices can open a promising unexplored field to fulfill specific requirements for kinetic and pharmacological trials.

  9. Preparation of a self-humidifying membrane electrode assembly for fuel cell and its performance analysis

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Mao, Zongqiang; Xu, Jingming; Xie, Xiaofeng; Yang, Lizhai

    2003-10-01

    A novel nano-porous material SiO2-gel was prepared. After being purified by H2O2, then protonized by H2SO4 and desiccated in vacuum, the SiO2-gel, mixed with Nafion solution, was coated between an electrode and a solid electrolyte, which made a new type of self-humidifying membrane electrode assembly. The SiO2 powder was characterized by FTIR, BET and XRD. The surface of the electrodes was characterized by SEM and EDS. The performances of the self-humidifying membrane electrodes were analyzed by polarization discharge and AC impedance under the operation modes of external humidification and self-humidification respectively. Experimental-results indicated that the SiO2 powder held super-hydrophilicity, and the layer of SiO2 and Nafion polymer between electrode and solid electrolyte expanded three-dimension electrochemistry reac-tion area, maintained stability of catalyst layer and enhanced back-diffusion of water from cathode to anode, so the PEM Fuel cell can generate electricity at self-humidification mode. The power density of single PEM fuel cell reached 1.5 W/cm2 under 0.2 Mpa, 70°C and dry hydrogen and oxygen.

  10. Cellulose acetate hollow fiber membranes blended with phospholipid polymer and their performance for hemopurification.

    PubMed

    Ye, Sang Ho; Watanabe, Junji; Ishihara, Kazuhiko

    2004-01-01

    Commercially available hollow fiber membranes (HFMs) made from synthetic polymers, including cellulose acetate (CA) HFMs, used as hemopurification membranes, need to improve in hemocompatibility, by suppressing protein adsorption and clot formation. In this study, CA HFMs blended with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer (PMB30 composed of MPC and n-butyl methacrylate (BMA)) were prepared by a dry-jet wet spinning process. Their performances were evaluated by characterizing their properties such as structure, permeability and protein adsorption. CA/PMB30-blend HFMs showed structure changes such as increase of porosity, development of large pores and decreasing of the thickness of the active layer. And the structure and permeability of CA/PMB30-blend HFMs were controllable by changing preparation conditions. Also, the CA/PMB30-blend HFMs had good permeability, low protein adsorption and low fouling property during the permeability experiment in comparison with CA HFMs, because the hydrophilic and hemocompatible MPC copolymer (PMB30) existed on the surface of the HFM.

  11. Oral impacts affecting daily performance in a low dental disease Thai population.

    PubMed

    Adulyanon, S; Vourapukjaru, J; Sheiham, A

    1996-12-01

    The aim of the study was to measure incidence of oral impacts on daily performances and their related features in a low dental disease population. 501 people aged 35-44 years in 16 rural villages in Ban Phang district, Khon Kaen, Thailand, were interviewed about oral impacts on nine physical, psychological and social aspects of performance during the past 6 months, and then had an oral examination. The clinical and behavioural data showed that the sample had low caries (DMFT = 2.7) and a low utilization of dental services. 73.6% of all subjects had at least one daily performance affected by an oral impact. The highest incidence of performances affected were Eating (49.7%), Emotional stability (46.5%) and Smiling (26.1%). Eating, Emotional stability and Cleaning teeth performances had a high frequency or long duration of impacts, but a low severity. The low frequency performances; Physical activities, Major role activity and Sleeping were rated as high severity. Pain and discomfort were mainly perceived as the causes of impacts (40.1%) for almost every performance except Smiling. Toothache was the major causal oral condition (32.7%) of almost all aspects of performance. It was concluded that this low caries people have as high an incidence of oral impacts as industrialized, high dental disease populations. Frequency and severity presented the paradoxical effect on different performances and should both be taken into account for overall estimation of impacts.

  12. [Research on the performance comparing and building of affective computing database based on physiological parameters].

    PubMed

    Li, Xin; Du, Xiaojuan; Zhang, Yunpeng; Ying, Lijuan; Li, Changwuz

    2014-08-01

    The validity and reasonableness of emotional data are the key issues in the cognitive affective computing research. Effects of the emotion recognition are decided by the quality of selected data directly. Therefore, it is an important part of affective computing research to build affective computing database with good performance, so that it is the hot spot of research in this field. In this paper, the performance of two classical cognitive affective computing databases, the Massachusetts Institute of Technology (MIT) cognitive affective computing database and Germany Augsburg University emotion recognition database were compared, their data structure and data types were compared respectively, and emotional recognition effect based on the data were studied comparatively. The results indicated that the analysis based on the physical parameters could get the effective emotional recognition, and would be a feasible method of pressure emotional evaluation. Because of the lack of stress emotional evaluation data based on the physiological parameters domestically, there is not a public stress emotional database. We hereby built a dataset for the stress evaluation towards the high stress group in colleges, candidates of postgraduates of Ph. D and master as the subjects. We then acquired their physiological parameters, and performed the pressure analysis based on this database. The results indicated that this dataset had a certain reference value for the stress evaluation, and we hope this research can provide a reference and support for emotion evaluation and analysis.

  13. Influence of ionomer content on the structure and performance of PEFC membrane electrode assemblies

    SciTech Connect

    Xie, Jian; Xu, Fan; WoodIII, David L; More, Karren Leslie; Zawodzinski, Thomas; Smith, Wayne H

    2010-01-01

    Nafion ionomer content of the cathode catalyst-layer of a polymer electrolyte fuel cell (PEFC), made by the decal hot pressing method, has been investigated for its effect on performance and structure of the membrane electrode assembly (MEA). Varying Nafion content was shown to have an effect on performance within the entire range of polarization curves (i.e. kinetic, ohmic, and mass-transport regions) as well as on the structure. AFM analysis shows the effect of Nafion on the dispersion of carbon aggregates. Further analysis using TEM demonstrates the effect of Nafion on both the dispersion of carbon aggregates and the distribution and thickness of the Nafion ionomer films surrounding the catalyst/carbon aggregates. The MEA structure change correlates well with the MEA performance on both kinetics and mass-transport region. The determining factors on the performance of MEA are the interfacial zone (between the ionomer and catalyst particle), the dispersion of catalyst/carbon aggregates and the distribution/thickness of Nafion films. An optimized Nafion content in the range of 27 6 wt.% for the cathode was determined for an E-TEK 20% Pt3Cr/C catalyst at a loading of 0.20mg Pt/cm2.

  14. Current short circuit implementation for performance improvement and lifetime extension of proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Zhan, Yuedong; Guo, Youguang; Zhu, Jianguo; Li, Li

    2014-12-01

    To improve its performance, extend its lifetime, and overcome the problem of the slow dynamic during the start-up and the operation process of a proton exchange membrane fuel cell (PEMFC), this paper presents current short circuit and smart energy management approaches for a main PEMFC with auxiliary PEMFC, battery and supercapacitor as hybrid power source in parallel with an intelligent uninterrupted power supply (UPS) system. The hybrid UPS system consists of two low-cost 63-cell 300 W PEMFC stacks, 3-cell lead-acid battery, and 20-cell series-connected supercapacitors. Based on the designed intelligent hybrid UPS system, experimental tests and theoretical studies are conducted. Firstly, the modeling of PEMFC is obtained and evaluated. Then the performance improvement mechanism of the current short circuit is proposed and analyzed based on the Faradaic process and non-Faradaic process of electrochemical theory. Finally, the performances of the main PEMFC with the auxiliary PEMFC/battery/supercapacitor hybrid power source and intelligent energy management are experimentally measured and analyzed. The proposed current short circuit method can significantly extend the lifetime, improve the performance of PEMFC and decrease the size of the main FC for stationary, backup power sources and vehicular applications.

  15. Antecedent Factors Affecting Academic Performance of Graduate Students at the Nairobi Evangelical Graduate School of Theology

    ERIC Educational Resources Information Center

    Mbogo, Rosemary Wahu

    2016-01-01

    This paper reports the findings of a Master's level thesis work that was done in 1997 to assess the antecedent factors affecting the academic performance of graduate students at the Nairobi Evangelical School of Theology (N.E.G.S.T.), which is currently Africa International University (AIU). The paper reviews the effect of lack of finance on…

  16. Internal Challenges Affecting Academic Performance of Student-Athletes in Ghanaian Public Universities

    ERIC Educational Resources Information Center

    Apaak, Daniel; Sarpong, Emmanuel Osei

    2015-01-01

    This paper examined internal challenges affecting academic performance of student-athletes in Ghanaian public universities, using a descriptive survey research design. Proportionate random sampling technique was employed to select Three Hundred and Thirty-Two (332) respondents for the study. The instrument used in gathering data for the study was…

  17. ULTRAFINE CARBON PARTICLE (UFCP) INHALATION AFFECTS CARDIOVASCULAR PERFORMANCE IN HYPERTENSIVE RATS (SHR)

    EPA Science Inventory

    Inhaled UfCP affect cardiovascular performance in healthy rats (Harder et al. Inhal Toxicol 2005; 17:29-42) without apparent pulmonary damage. To assess whether geriatric cardiovascular compromised rats are more susceptible to UfCP effects, male adult (6months) and geriatric (13m...

  18. Factors Affecting University Entrants' Performance in High-Stakes Tests: A Multiple Regression Analysis

    ERIC Educational Resources Information Center

    Uy, Chin; Manalo, Ronaldo A.; Cabauatan, Ronaldo R.

    2015-01-01

    In the Philippines, students seeking admission to a university are usually required to meet certain entrance requirements, including passing the entrance examinations with questions on IQ and English, mathematics, and science. This paper aims to determine the factors that affect the performance of entrants into business programmes in high-stakes…

  19. Students Perceptions on Factors That Affect Their Academic Performance: The Case of Great Zimbabwe University (GZU)

    ERIC Educational Resources Information Center

    Mapuranga, Barbra; Musingafi, Maxwell C. C.; Zebron, Shupikai

    2015-01-01

    Some educators argue that entry standards are the most important determinants of successful completion of a university programme; others maintain that non-academic factors must also be considered. In this study we sought to investigate open and distance learning students' perceptions of the factors affecting academic performance and successful…

  20. Motivating Factors that Affect Enrolment and Student Performance in an ODL Engineering Program

    ERIC Educational Resources Information Center

    Dadigamuwa, P. R.; Senanayake, Samans

    2012-01-01

    The present study was carried out to determine the motivating factors for enrolling in an engineering study programme in open and distance learning (ODL) and the factors that affect the students' performance. The study was conducted with two convenient samples of students following distance learning courses in engineering technology, conducted by…

  1. Study of Core Competency Elements and Factors Affecting Performance Efficiency of Government Teachers in Northeastern Thailand

    ERIC Educational Resources Information Center

    Chansirisira, Pacharawit

    2012-01-01

    The research aimed to investigate the core competency elements and the factors affecting the performance efficiency of the civil service teachers in the northeastern region, Thailand. The research procedure consisted of two steps. In the first step, the data were collected using a questionnaire with the reliability (Cronbach's Alpha) of 0.90. The…

  2. Novel synthesis of FAU-type zeolite membrane with high performance.

    PubMed

    Cheng, Zhilin; Gao, Enqing; Wan, Huilin

    2004-08-07

    FAU-type zeolite membranes were synthesized by the vapor phase transformation (VPT) methods with or without prior seeding on the substrate, and it was revealed that the CO(2)/N(2) selectivity of the seeded membrane is greater than that of the unseeded membrane.

  3. Antimicrobial PVK:SWNT nanocomposite coated membrane for water purification: performance and toxicity testing.

    PubMed

    Ahmed, Farid; Santos, Catherine M; Mangadlao, Joey; Advincula, Rigoberto; Rodrigues, Debora F

    2013-08-01

    This study demonstrated that coated nitrocellulose membranes with a nanocomposite containing 97% (wt%) of polyvinyl-N-carbazole (PVK) and 3% (wt%) of single-walled carbon nanotubes (SWNTs) (97:3 wt% ratio PVK:SWNT) achieve similar or improved removal of bacteria when compared with 100% SWNTs coated membranes. Membranes coated with the nanocomposite exhibited significant antimicrobial activity toward Gram-positive and Gram-negative bacteria (≈ 80-90%); and presented a virus removal efficiency of ≈ 2.5 logs. Bacterial cell membrane damage was considered a possible mechanism of cellular inactivation since higher efflux of intracellular material (Deoxyribonucleic acid, DNA) was quantified in the filtrate of PVK-SWNT and SWNT membranes than in the filtrate of control membranes. To evaluate possible application of these membrane filters for drinking water treatment, toxicity of PVK-SWNT was tested against fibroblast cells. The results demonstrated that PVK-SWNT was non toxic to fibroblast cells as opposed to pure SWNT (100%). These results suggest that it is possible to synthesize antimicrobial nitrocellulose membranes coated with SWNT based nanocomposites for drinking water treatment. Furthermore, membrane filters coated with the nanocomposite PVK-SWNT (97:3 wt% ratio PVK:SWNT) will produce more suitable coated membranes for drinking water than pure SWNTs coated membranes (100%), since the reduced load of SWNT in the nanocomposite will reduce the use of costly and toxic SWNT nanomaterial on the membranes.

  4. A general mathematical model for analyzing the performance of fuel-cell membrane-electrode assemblies

    NASA Astrophysics Data System (ADS)

    Zhu, Huayang; Kee, Robert J.

    We have developed a general mathematical model to represent the membrane-electrode assembly (MEA) of fuel-cell systems. The model is used to analyze the effects of various polarization resistances on cell performance. The model accommodates arbitrary gas mixtures on the anode and cathode sides of the MEA. Moreover, it accommodates a variety of porous electrode and electrolyte structures. Concentration overpotentials are based on a dusty-gas representation of transport through porous electrodes. The activation overpotentials are represented using the Butler-Volmer equation. Although the model is general, the emphasis in this paper is on solid-oxide fuel-cell (SOFC) systems for the direct electrochemical oxidation (DECO) of hydrocarbons.

  5. Statistical Simulation of the Performance and Degradation of a PEMFC Membrane Electrode Assembly

    SciTech Connect

    Harvey, David; Bellemare-Davis, Alexander; Karan, Kunal; Jayansankar, Barath; Pharoah, Jon; Colbow, Vesna; Young, Alan; Wessel, Silvia

    2012-07-01

    A 1-D MEA Performance model was developed that considered transport of liquid water, agglomerate catalyst structure, and the statistical variation of the MEA characteristic parameters. The model was validated against a low surface area carbon supported catalyst across various platinum loadings and operational conditions. The statistical variation was found to play a significant role in creating noise in the validation data and that there was a coupling effect between movement in material properties with liquid water transport. Further, in studying the low platinum loaded catalyst layers it was found that liquid water played a significant role in the increasing the overall transport losses. The model was then further applied to study platinum dissolution via potential cycling accelerated stress tests, in which the platinum was found to dissolve nearest the membrane effectively resulting in reaction distribution shifts within the layer.

  6. Predicting nitrogen loading with land-cover composition: how can watershed size affect model performance?

    PubMed

    Zhang, Tao; Yang, Xiaojun

    2013-01-01

    Watershed-wide land-cover proportions can be used to predict the in-stream non-point source pollutant loadings through regression modeling. However, the model performance can vary greatly across different study sites and among various watersheds. Existing literature has shown that this type of regression modeling tends to perform better for large watersheds than for small ones, and that such a performance variation has been largely linked with different interwatershed landscape heterogeneity levels. The purpose of this study is to further examine the previously mentioned empirical observation based on a set of watersheds in the northern part of Georgia (USA) to explore the underlying causes of the variation in model performance. Through the combined use of the neutral landscape modeling approach and a spatially explicit nutrient loading model, we tested whether the regression model performance variation over the watershed groups ranging in size is due to the different watershed landscape heterogeneity levels. We adopted three neutral landscape modeling criteria that were tied with different similarity levels in watershed landscape properties and used the nutrient loading model to estimate the nitrogen loads for these neutral watersheds. Then we compared the regression model performance for the real and neutral landscape scenarios, respectively. We found that watershed size can affect the regression model performance both directly and indirectly. Along with the indirect effect through interwatershed heterogeneity, watershed size can directly affect the model performance over the watersheds varying in size. We also found that the regression model performance can be more significantly affected by other physiographic properties shaping nitrogen delivery effectiveness than the watershed land-cover heterogeneity. This study contrasts with many existing studies because it goes beyond hypothesis formulation based on empirical observations and into hypothesis testing to

  7. Nutritional effects of egg shell membrane supplements on chicken performance and immunity.

    PubMed

    Makkar, S; Rath, N C; Packialakshmi, B; Huff, W E; Huff, G R

    2015-06-01

    Eggshell membranes (ESM) contain a variety of proteins and peptides which help in the development of embryo and provide protection to it. Many of the peptides and proteins associated with ESM have antimicrobial, immune-modulatory, and adjuvant properties. We hypothesized that the membrane byproducts from egg, provided as posthatch nutritional supplements to chickens, may improve their performance and immunity. To explore its effect, we fed 3 groups of broiler chicks with feed containing 0, 0.2, and 0.4% ESM from d 1 posthatch through 14 d and regular feed thereafter. The birds were individually weighed at the onset of the study and at weekly intervals until the termination at third wk when they were bled and euthanized. The relative weights of liver, spleen, bursa, and heart, hematology profiles, and clinical chemistry variables including serum IgM, IgG, and corticosterone concentrations were measured. The chickens in the ESM treated groups showed a statistically significant increase in BW with no impact on relative organ weights. Compared with controls, the WBC and lymphocyte percentage increased in chickens fed 0.4% ESM whereas the monocyte percentage decreased at both levels of ESM. Except for the serum protein which increased in ESM fed birds no other metabolic clinical chemistry variables showed any significant change. Both IgM and IgG(Y) levels were elevated and corticosterone levels reduced in chickens fed ESM supplemented diets. Our results suggest that ESM supplements during the early phases of growth may improve immunity and stress variables, and enhance their growth performance without any detrimental effect on other physiological parameters.

  8. Nutritional Supplement of Hatchery Eggshell Membrane Improves Poultry Performance and Provides Resistance against Endotoxin Stress

    PubMed Central

    Makkar, S. K.; Rath, N. C.; Packialakshmi, B.; Zhou, Z. Y.; Huff, G. R.; Donoghue, A. M.

    2016-01-01

    Eggshells are significant part of hatchery waste which consist of calcium carbonate crust, membranes, and proteins and peptides of embryonic origins along with other entrapped contaminants including microbes. We hypothesized that using this product as a nutritional additive in poultry diet may confer better immunity to the chickens in the paradigm of mammalian milk that enhances immunity. Therefore, we investigated the effect of hatchery eggshell membranes (HESM) as a short term feed supplement on growth performance and immunity of chickens under bacterial lipopolysaccharide (LPS) challenged condition. Three studies were conducted to find the effect of HESM supplement on post hatch chickens. In the first study, the chickens were fed either a control diet or diets containing 0.5% whey protein or HESM as supplement and evaluated at 5 weeks of age using growth, hematology, clinical chemistry, plasma immunoglobulins, and corticosterone as variables. The second and third studies were done to compare the effects of LPS on control and HESM fed birds at 5 weeks of age following at 4 and 24 h of treatment where the HESM was also sterilized with ethanol to deplete bacterial factors. HESM supplement caused weight gain in 2 experiments and decreased blood corticosterone concentrations. While LPS caused a significant loss in body weight at 24 h following its administration, the HESM supplemented birds showed significantly less body weight loss compared with the control fed birds. The WBC, heterophil/lymphocyte ratio, and the levels of IgG were low in chickens fed diets with HESM supplement compared with control diet group. LPS challenge increased the expression of pro-inflammatory cytokine gene IL-6 but the HESM fed birds showed its effect curtailed, also, which also, favored the up-regulation of anti-inflammatory genes compared with control diet fed chickens. Post hatch supplementation of HESM appears to improve performance, modulate immunity, and increase resistance of

  9. Influence of silica nanospheres on the separation performance of thin film composite poly(piperazine-amide) nanofiltration membranes

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Wang, Yihua; Song, Jie; Guan, Yipeng; Yu, Hui; Pan, Xianhui; Wu, Feiyang; Zhang, Meng

    2015-01-01

    A novel thin film nanocomposite nanofiltration (TFNN) membrane was fabricated by introducing silica nanospheres (ca. 235 ± 11 nm) in the interfacial polymerization process of trimesoyl chloride (TMC) and piperazine (PIP) over polysulfone (PS) support for investigating the effect of silica nanofiller on the separation performance (i.e., permeability and salt rejection) of conventional thin film composite poly(piperazine-amide) nanofiltration (TFCN) membrane. The physicochemical characterization results show that all of the silica nanospheres are uniformly embedded on the surface of TFNN membrane. The introduction of silica nanospheres improves the hydrophilicity of the TFCN membrane and also causes its isoelectric point shift to a lower pH value. Moreover, the active poly(piperazine-amide) barrier layer of TFNN membrane (60.8 ± 2.3 nm) is thinner than that of the pristine TFCN membrane (72.1 ± 2.5 nm) as a control sample. The separation performance tests reveal that the addition of silica nanospheres can obviously elevate the salt rejection of the pristine TFCN membrane from 87.58 ± 0.15 to 94.81 ± 0.17% under 2000 ppm of MgSO4 solution and 0.5 MPa operating pressure, simultaneously accompanied by the increases of permeate flux from 19.36 ± 0.75 to 22.65 ± 0.68 L/m2 h. Additionally, compared with pristine TFCN membrane, the fabricated TFNN membrane has relatively low salt rejection (43.20 ± 0.27%) in 0.5 MPa operating pressure for 500 ppm of NaCl aqueous solution, which demonstrates that the introduction of silica nanospheres can dramatically promote the divalent-ionic separation selectivity. Furthermore, the experimental results suggest that the nanocomposite TFNN membrane possesses stable filtration performance in the softening process of MgSO4 aqueous solution. The separation performance improvement should be attributed to the optimizations of microstructures and surface features of active barrier layer of TFNN membrane, caused by the addition of silica

  10. The influence of membrane electrode assembly water content on the performance of a polymer electrolyte membrane fuel cell as investigated by 1H NMR microscopy.

    PubMed

    Feindel, Kirk W; Bergens, Steven H; Wasylishen, Roderick E

    2007-04-21

    The relation between the performance of a self-humidifying H(2)/O(2) polymer electrolyte membrane fuel cell and the amount and distribution of water as observed using (1)H NMR microscopy was investigated. The integrated (1)H NMR image signal intensity (proportional to water content) from the region of the polymer electrolyte membrane between the catalyst layers was found to correlate well with the power output of the fuel cell. Several examples are provided which demonstrate the sensitivity of the (1)H NMR image intensity to the operating conditions of the fuel cell. Changes in the O(2)(g) flow rate cause predictable trends in both the power density and the image intensity. Higher power densities, achieved by decreasing the resistance of the external circuit, were found to increase the water in the PEM. An observed plateau of both the power density and the integrated (1)H NMR image signal intensity from the membrane electrode assembly and subsequent decline of the power density is postulated to result from the accumulation of H(2)O(l) in the gas diffusion layer and cathode flow field. The potential of using (1)H NMR microscopy to obtain the absolute water content of the polymer electrolyte membrane is discussed and several recommendations for future research are provided.

  11. Universal and culture-specific factors in the recognition and performance of musical affect expressions.

    PubMed

    Laukka, Petri; Eerola, Tuomas; Thingujam, Nutankumar S; Yamasaki, Teruo; Beller, Grégory

    2013-06-01

    We present a cross-cultural study on the performance and perception of affective expression in music. Professional bowed-string musicians from different musical traditions (Swedish folk music, Hindustani classical music, Japanese traditional music, and Western classical music) were instructed to perform short pieces of music to convey 11 emotions and related states to listeners. All musical stimuli were judged by Swedish, Indian, and Japanese participants in a balanced design, and a variety of acoustic and musical cues were extracted. Results first showed that the musicians' expressive intentions could be recognized with accuracy above chance both within and across musical cultures, but communication was, in general, more accurate for culturally familiar versus unfamiliar music, and for basic emotions versus nonbasic affective states. We further used a lens-model approach to describe the relations between the strategies that musicians use to convey various expressions and listeners' perceptions of the affective content of the music. Many acoustic and musical cues were similarly correlated with both the musicians' expressive intentions and the listeners' affective judgments across musical cultures, but the match between musicians' and listeners' uses of cues was better in within-cultural versus cross-cultural conditions. We conclude that affective expression in music may depend on a combination of universal and culture-specific factors.

  12. Enhanced performance of anion exchange membranes via crosslinking of ion cluster regions for fuel cells

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Development of anion exchange membranes (AEMs) with high hydroxide conductivity, good dimensional and alkaline stabilities is still a challenge for the practical application of AEM fuel cells. In this study, we report a new strategy to prepare high-performance AEMs with crosslinked ionic regions. A series of phenolphthalein-containing poly(arylene ether sulfone)s crosslinked AEMs was synthesized by grafting ion groups selectively and densely on the phenolphthalein units to form ion clusters that are further crosslinked to generate the hydrophilic ionic regions. The crosslinking reaction not only improved the dimensional stability of the AEMs, but also increased the aggregation of the ion clusters leading to the formation of hydrophilic/hydrophobic phase-separated morphology and ion-conducting channels. As a result, enhancements in both ion conductivity and dimensional stability can be achieved. The crosslinked AEMs showed high hydroxide conductivities in the range of 52.2-143.4 mS cm-1 from 30 to 80 °C and a superb ratio of relative conductivity to relative swelling at 80 °C. Furthermore, the crosslinked AEMs also exhibited good mechanical properties, thermal and alkaline stabilities and desirable single cell performance. This work presents a promising strategy for the synthesis of high-performance AEMs for fuel cells.

  13. Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin

    2014-01-01

    Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a recirculating control loop which had no water quality maintenance. Results show that periodic water maintenance can improve performance of the SWME. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage of this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the evaluation of water recirculation maintenance components was to enhance the robustness of the SWME through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A patented bed design that was developed for a United Technologies Aerospace System military application provided a low pressure drop means for water maintenance in the SWME recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for the ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

  14. A Quality Improvement Study on Avoidable Stressors and Countermeasures Affecting Surgical Motor Performance and Learning

    PubMed Central

    Conrad, Claudius; Konuk, Yusuf; Werner, Paul D.; Cao, Caroline G.; Warshaw, Andrew L.; Rattner, David W.; Stangenberg, Lars; Ott, Harald C.; Jones, Daniel B.; Miller, Diane L; Gee, Denise W.

    2012-01-01

    OBJECTIVE To explore how the two most important components of surgical performance - speed and accuracy - are influenced by different forms of stress and what the impact of music on these factors is. SUMMARY BACKGROUND DATA Based on a recently published pilot study on surgical experts, we designed an experiment examining the effects of auditory stress, mental stress, and music on surgical performance and learning, and then correlated the data psychometric measures to the role of music in a novice surgeon’s life. METHODS 31 surgeons were recruited for a crossover study. Surgeons were randomized to four simple standardized tasks to be performed on the Surgical SIM VR laparoscopic simulator, allowing exact tracking of speed and accuracy. Tasks were performed under a variety of conditions, including silence, dichotic music (auditory stress), defined classical music (auditory relaxation), and mental loading (mental arithmetic tasks). Tasks were performed twice to test for memory consolidation and to accommodate for baseline variability. Performance was correlated to the Brief Musical Experience Questionnaire (MEQ). RESULTS Mental loading influences performance with respect to accuracy, speed, and recall more negatively than does auditory stress. Defined classical music might lead to minimally worse performance initially, but leads to significantly improved memory consolidation. Furthermore, psychologic testing of the volunteers suggests that surgeons with greater musical commitment, measured by the MEQ, perform worse under the mental loading condition. CONCLUSION Mental distraction and auditory stress negatively affect specific components of surgical learning and performance. If used appropriately, classical music may positively affect surgical memory consolidation. It also may be possible to predict surgeons’ performance and learning under stress through psychological tests on the role of music in a surgeon’s life. Further investigation is necessary to determine

  15. Synthesis and Performance Evaluations of SAPO-34 Membranes- Milestone Report for FCRD-MRWFD-2016-000263

    SciTech Connect

    Bhave, Ramesh R.; Jubin, Robert Thomas; Spencer, Barry B.; Nair, Sankar

    2016-07-01

    This report describes the synthesis and evaluation of molecular sieve zeolite membranes to separate and concentrate tritiated water (HTO) from dilute HTO-bearing aqueous streams. Several silico alumino phosphate (SAPO-34) molecular sieve zeolite membranes were synthesized on tubular supports and characterized with gas and vapor permeation measurements. The pervaporation process performance was evaluated for the separation and concentration of tritiated water. Experiments were performed over a range of tritiated water concentration that correspond to the range anticipated in a nuclear fuel processing system that includes both acid and water streams recycling. The permeate was recovered under vacuum. The tritium concentration ranged from 0.5 to 1 mCi/mL which is about 0.1 mg/L or 0.1 ppm. The separation factors calculated from the measured tritium concentrations ranged from 0.83-0.98. The HTO concentration was three orders of magnitude lower than prior experiments performed with simulated feed containing HDO (>100 ppm) using deuterated water where high separation factors (>10) were obtained using SAPO membranes on alumina disk supports. Although the membrane performance characterization results for HTO were lower than expected, they can be explained on the basis of low feed volume and three orders of magnitude lower HTO concentration compared to HDO concentration in deuterated water. Several new approaches are proposed, such as tuning the diffusion coefficient of HTO, and optimization of membrane thickness that may help achieve preferential transport of tritium (HTO) resulting in a substantially more concentrated permeate.

  16. Multilayered poly(vinylidene fluoride) composite membranes with improved interfacial compatibility: correlating pervaporation performance with free volume properties.

    PubMed

    An, Quanfu; Chen, Jung-Tsai; De Guzman, Manuel; Hung, Wei-Song; Lee, Kueir-Rarn; Lai, Juin-Yih

    2011-09-06

    A spin-coating process integrated with an ozone-induced graft polymerization technique was applied in this study. The purpose was to improve the poor interfacial compatibility between a selective layer of poly(2-hydroxyethyl methacrylate) (PHEMA) and the surface of a poly(vinylidene fluoride) (PVDF) substrate. The composite membranes thus fabricated were tested for their pervaporation performance in dehydrating an ethyl acetate/water mixture. Furthermore, the composite membranes were characterized by field emission scanning electron microscopy (FE-SEM) for morphological change observation and by Fourier transform infrared spectroscopy equipped with attenuated total reflectance (ATR-FTIR) for surface chemical composition analysis. Effects of grafting density and spin-coating speed on pervaporation performance were examined. The composite membrane pervaporation performance was elucidated by means of free volume and depth profile data obtained with the use of a variable monoenergy slow positron beam (VMSPB). Results indicated that a smaller free volume was correlated with a higher pervaporation performance of a composite membrane consisting of a selective layer of spin-coated PHEMA on a PHEMA-grafted PVDF substrate (S-PHEMA/PHEMA-g-PVDF). The composite membrane depth profile illustrated that an S-PHEMA layer spin-coated at a higher revolutions per minute (rpm) was thinner and denser than that at a lower rpm.

  17. Enhanced pervaporation performance of multi-layer PDMS/PVDF composite membrane for ethanol recovery from aqueous solution.

    PubMed

    Zhan, Xia; Li, Jiding; Huang, Junqi; Chen, Cuixian

    2010-01-01

    Multi-layer PDMS/PVDF composite membrane with an alternative PDMS/PVDF/non-woven-fiber/PVDF/PDMS configuration was prepared in this paper. The porous PVDF substrate was obtained by casting PVDF solution on both sides of non-woven fiber with immersion precipitation phase inversion method. Polydimethylsiloxane (PDMS) was then cured by phenyltrimethoxylsilane (PTMOS) and coated onto the surface of porous PVDF substrate one layer by the other to obtain multi-layer PDMS/PVDF composite membrane. The multi-layer composite membrane was used for ethanol recovery from aqueous solution by pervaporation, and exhibited enhanced separation performance compared with one side PDMS/PVDF composite membranes, especially in the low ethanol concentration range. The maximum separation factor of multi-layer PDMS/PVDF composite membrane was obtained at 60 degrees C, and the total flux increased exponentially along with the increase of temperature. The composite membrane gave the best pervaporation performance with a separation factor of 15, permeation rate of 450 g/m(2)h with a 5 wt.% ethanol concentration at 60 degrees C.

  18. The absence of chlorophyll b affects lateral mobility of photosynthetic complexes and lipids in grana membranes of Arabidopsis and barley chlorina mutants.

    PubMed

    Tyutereva, Elena V; Evkaikina, Anastasiia I; Ivanova, Alexandra N; Voitsekhovskaja, Olga V

    2017-04-05

    The lateral mobility of integral components of thylakoid membranes, such as plastoquinone, xanthophylls, and pigment-protein complexes, is critical for the maintenance of efficient light harvesting, high rates of linear electron transport, and successful repair of damaged photosystem II (PSII). The packaging of the photosynthetic pigment-protein complexes in the membrane depends on their size and stereometric parameters which in turn depend on the composition of the complexes. Chlorophyll b (Chlb) is an important regulator of antenna size and composition. In this study, the lateral mobility (the mobile fraction size) of pigment-protein complexes and lipids in grana membranes was analyzed in chlorina mutants of Arabidopsis and barley lacking Chlb. In the Arabidopsis ch1-3 mutant, diffusion of membrane lipids decreased as compared to wild-type plants, but the diffusion of photosynthetic complexes was not affected. In the barley chlorina f2 3613 mutant, the diffusion of pigment-protein complexes significantly decreased, while the diffusion of lipids increased, as compared to wild-type plants. We propose that the size of the mobile fractions of pigment-protein complexes in grana membranes in vivo is higher than reported previously. The data are discussed in the context of the protein composition of antennae, characteristics of the plastoquinone pool, and production of reactive oxygen species in leaves of chlorina mutants.

  19. Performance and sleepiness during a 24 h wake in constant conditions are affected by diet.

    PubMed

    Lowden, Arne; Holmbäck, Ulf; Akerstedt, Torbjörn; Forslund, Jeanette; Lennernäs, Maria; Forslund, Anders

    2004-02-01

    This study investigated the effects of high-carbohydrate (HC) and high-fat (HF) diet on cognitive performance, and subjective and objective sleepiness. Seven male participants were kept awake for 24 h in a metabolic ward. Meals were given every 4h and cognitive performance and sleepiness ratings were assessed hourly. The Karolinska Drowsiness Test (KDT, EEG derived) was performed twice after meal. Performance in simple reaction time showed a significant interaction of diet and the post-prandial period, a slower reaction time was observed for the HC-diet 3.5 h after meal intake. Diet did not affect EEG measures but a general post-prandial increase of objective sleepiness was observed 3.5h after meal servings. The HC-diet was significantly associated with an increase of subjective sleepiness. The study demonstrated that the HC-diet caused larger oscillation in performance and increased sleepiness as compared to HF-diet throughout day and night.

  20. Performance Validation and Scaling of a Capillary Membrane Solid-Liquid Separation System

    SciTech Connect

    Rogers, S; Cook, J; Juratovac, J; Goodwillie, J; Burke, T

    2011-10-25

    Algaeventure Systems (AVS) has previously demonstrated an innovative technology for dewatering algae slurries that dramatically reduces energy consumption by utilizing surface physics and capillary action. Funded by a $6M ARPA-E award, transforming the original Harvesting, Dewatering and Drying (HDD) prototype machine into a commercially viable technology has required significant attention to material performance, integration of sensors and control systems, and especially addressing scaling issues that would allow processing extreme volumes of algal cultivation media/slurry. Decoupling the harvesting, dewatering and drying processes, and addressing the rate limiting steps for each of the individual steps has allowed for the development individual technologies that may be tailored to the specific needs of various cultivation systems. The primary performance metric used by AVS to assess the economic viability of its Solid-Liquid Separation (SLS) dewatering technology is algae mass production rate as a function of power consumption (cost), cake solids/moisture content, and solids capture efficiency. An associated secondary performance metric is algae mass loading rate which is dependent on hydraulic loading rate, area-specific hydraulic processing capacity (gpm/in2), filter:capillary belt contact area, and influent algae concentration. The system is capable of dewatering 4 g/L (0.4%) algae streams to solids concentrations up to 30% with capture efficiencies of 80+%, however mass production is highly dependent on average cell size (which determines filter mesh size and percent open area). This paper will present data detailing the scaling efforts to date. Characterization and performance data for novel membranes, as well as optimization of off-the-shelf filter materials will be examined. Third party validation from Ohio University on performance and operating cost, as well as design modification suggestions will be discussed. Extrapolation of current productivities

  1. Time-dependence of pervaporation performance for the separation of ethanol/water mixtures through poly(vinyl alcohol) membrane.

    PubMed

    Li, Gewei; Zhang, Wei; Yang, Juping; Wang, Xinping

    2007-02-15

    To clarify the cause of time-dependent separation behavior, the pervaporation performance with operating time through pure poly(vinyl alcohol) (PVA) membrane and glutaraldehyde (GA) cross-linked PVA membranes was investigated. The results showed that the water concentration in the permeate for the air-side surface of the PVA membrane increased dramatically from 92.2 to 95.7% in about 110 min and then remained almost unchanged. However, the water selectivity for the glass-side surface did not change with operating time. Similar results were observed for the GA cross-linked PVA membranes. Furthermore, the contact angle of water on the air-side surfaces of those membranes decreased with the time of contact with the feed. These results revealed that this dynamic pervaporation process was mainly attributable to the reconstruction of hydroxyl groups at the air-side surfaces of PVA membranes in response to the change of their surrounding medium during pervaporation. The reconstruction at the glass-side surface of the membrane did not occur because of the preferential localization of hydroxyl groups at the interface between the membrane and the glass plate during film formation of PVA solution. The above conclusion was further confirmed by the following results. The water concentration in the permeate through PVA membranes with the air-side surface facing the feed reached equilibrium more quickly with increasing operation temperature or decreasing degree of cross-linking, which was consistent with the fact that the rate of surface reconstruction accelerated with the increase of temperature or the decrease of the degree of cross-linking.

  2. Human resources management and firm performance: The differential role of managerial affective and continuance commitment.

    PubMed

    Gong, Yaping; Law, Kenneth S; Chang, Song; Xin, Katherine R

    2009-01-01

    In this study, the authors developed a dual-concern (i.e., maintenance and performance) model of human resources (HR) management. The authors identified commonly examined HR practices that apply to the middle manager level and classified them into the maintenance- and performance-oriented HR subsystems. The authors found support for the 2-factor model on the basis of responses from 2,148 managers from 463 firms operating in China. Regression results indicate that the performance-oriented HR subsystems had a positive relationship with firm performance and that the relationship was mediated by middle managers' affective commitment to the firm. The maintenance-oriented HR subsystems had a positive relationship with middle managers' continuance commitment but not with their affective commitment and firm performance. This study contributes to the understanding of how HR practices relate to firm performance and offers an improved test of the argument that valuable and firm-specific HR provide a source of competitive advantage. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

  3. Centrality and charisma: comparing how leader networks and attributions affect team performance.

    PubMed

    Balkundi, Prasad; Kilduff, Martin; Harrison, David A

    2011-11-01

    When leaders interact in teams with their subordinates, they build social capital that can have positive effects on team performance. Does this social capital affect team performance because subordinates come to see the leader as charismatic? We answered this question by examining 2 models. First, we tested the charisma-to-centrality model according to which the leader's charisma facilitates the occupation of a central position in the informal advice network. From this central position, the leader positively influences team performance. Second, we examined the centrality-to-charisma model according to which charisma is attributed to those leaders who are socially active in terms of giving and receiving advice. Attributed charisma facilitates increased team performance. We tested these 2 models in 2 different studies. In the first study, based on time-separated, multisource data emanating from members of 56 work teams, we found support for the centrality-to-charisma model. Formal leaders who were central within team advice networks were seen as charismatic by subordinates, and this charisma was associated with high team performance. To clarify how leader network centrality affected the emergence of charismatic leadership, we designed Study 2 in which, for 79 student teams, we measured leader networking activity and leader charisma at 2 different points in time and related these variables to team performance measured at a third point in time. On the basis of this temporally separated data set, we again found support for the centrality-to-charisma model.

  4. Screening antiallergic components from Carthamus tinctorius using rat basophilic leukemia 2H3 cell membrane chromatography combined with high-performance liquid chromatography and tandem mass spectrometry.

    PubMed

    Han, Shengli; Huang, Jing; Cui, Ronghua; Zhang, Tao

    2015-02-01

    Carthamus tinctorius, used in traditional Chinese medicine, has many pharmacological effects, such as anticoagulant effects, antioxidant effects, antiaging effects, regulation of gene expression, and antitumor effects. However, there is no report on the antiallergic effects of the components in C. tinctorius. In the present study, we investigated the antiallergic components of C. tinctorius and its mechanism of action. A rat basophilic leukemia 2H3/cell membrane chromatography coupled online with high-performance liquid chromatography and tandem mass spectrometry method was developed to screen antiallergic components from C. tinctorius. The screening results showed that Hydroxysafflor yellow A, from C. tinctorius, was the targeted component that retained on the rat basophilic leukemia 2H3/cell membrane chromatography column. We measured the amount of β-hexosaminidase and histamine released in mast cells and the key markers of degranulation. The release assays showed that Hydroxysafflor yellow A could attenuate the immunoglobulin E induced release of allergic cytokines without affecting cell viability from 1.0 to 50.0 μM. In conclusion, the established rat basophilic leukemia 2H3 cell membrane chromatography coupled with online high-performance liquid chromatography and tandem mass spectrometry method successfully screened and identified Hydroxysafflor yellow A from C. tinctorius as a potential antiallergic component. Pharmacological analysis elucidated that Hydroxysafflor yellow A is an effective natural component for inhibiting immunoglobulin E-antigen-mediated degranulation.

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

    SciTech Connect

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

    1994-08-01

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

  6. Virus removal retention challenge tests performed at lab scale and pilot scale during operation of membrane units.

    PubMed

    Humbert, H; Machinal, C; Labaye, Ivan; Schrotter, J C

    2011-01-01

    The determination of the virus retention capabilities of UF units during operation is essential for the operators of drinking water treatment facilities in order to guarantee an efficient and stable removal of viruses through time. In previous studies, an effective method (MS2-phage challenge tests) was developed by the Water Research Center of Veolia Environnement for the measurement of the virus retention rates (Log Removal Rate, LRV) of commercially available hollow fiber membranes at lab scale. In the present work, the protocol for monitoring membrane performance was transferred from lab scale to pilot scale. Membrane performances were evaluated during pilot trial and compared to the results obtained at lab scale with fibers taken from the pilot plant modules. PFU culture method was compared to RT-PCR method for the calculation of LRV in both cases. Preliminary tests at lab scale showed that both methods can be used interchangeably. For tests conducted on virgin membrane, a good consistency was observed between lab and pilot scale results with the two analytical methods used. This work intends to show that a reliable determination of the membranes performances based on RT-PCR analytical method can be achieved during the operation of the UF units.

  7. Using representations in geometry: a model of students' cognitive and affective performance

    NASA Astrophysics Data System (ADS)

    Panaoura, Areti

    2014-05-01

    Self-efficacy beliefs in mathematics, as a dimension of the affective domain, are related with students' performance on solving tasks and mainly on overcoming cognitive obstacles. The present study investigated the interrelations of cognitive performance on geometry and young students' self-efficacy beliefs about using representations for solving geometrical tasks. The emphasis was on confirming a theoretical model for the primary-school and secondary-school students and identifying the differences and similarities for the two ages. A quantitative study was developed and data were collected from 1086 students in Grades 5-8. Confirmatory factor analysis affirmed the existence of a coherent model of affective dimensions about the use of representations for understanding the geometrical concepts, which becomes more stable across the educational levels.

  8. Fabrication Method for Laboratory-Scale High-Performance Membrane Electrode Assemblies for Fuel Cells.

    PubMed

    Sassin, Megan B; Garsany, Yannick; Gould, Benjamin D; Swider-Lyons, Karen E

    2017-01-03

    Custom catalyst-coated membranes (CCMs) and membrane electrode assemblies (MEAs) are necessary for the evaluation of advanced electrocatalysts, gas diffusion media (GDM), ionomers, polymer electrolyte membranes (PEMs), and electrode structures designed for use in next-generation fuel cells, electrolyzers, or flow batteries. This Feature provides a reliable and reproducible fabrication protocol for laboratory scale (10 cm(2)) fuel cells based on ultrasonic spray deposition of a standard Pt/carbon electrocatalyst directly onto a perfluorosulfonic acid PEM.

  9. Relationship between performance deterioration of a polyamide reverse osmosis membrane used in a seawater desalination plant and changes in its physicochemical properties.

    PubMed

    Suzuki, Tasuma; Tanaka, Ryohei; Tahara, Marina; Isamu, Yuya; Niinae, Masakazu; Lin, Lin; Wang, Jingbo; Luh, Jeanne; Coronell, Orlando

    2016-09-01

    While it is known that the performance of reverse osmosis membranes is dependent on their physicochemical properties, the existing literature studying membranes used in treatment facilities generally focuses on foulant layers or performance changes due to fouling, not on the performance and physicochemical changes that occur to the membranes themselves. In this study, the performance and physicochemical properties of a polyamide reverse osmosis membrane used for three years in a seawater desalination plant were compared to those of a corresponding unused membrane. The relationship between performance changes during long-term use and changes in physicochemical properties was evaluated. The results showed that membrane performance deterioration (i.e., reduced water flux, reduced contaminant rejection, and increased fouling propensity) occurred as a result of membrane use in the desalination facility, and that the main physicochemical changes responsible for performance deterioration were reduction in PVA coating coverage and bromine uptake by polyamide. The latter was likely promoted by oxidant residual in the membrane feed water. Our findings indicate that the optimization of membrane materials and processes towards maximizing the stability of the PVA coating and ensuring complete removal of oxidants in feed waters would minimize membrane performance deterioration in water purification facilities.

  10. Risk factors and impact of retained fetal membranes on performance of dairy bovines reared under subtropical conditions.

    PubMed

    Kumari, Susavi; Prasad, Shiv; Kumaresan, Arumugam; Manimaran, Ayyasamy; Patbandha, Tapas Kumar; Pathak, Rupal; Boro, Prasanta; Mohanty, Tushar Kumar; Ravi, Sanjay Kumar

    2015-02-01

    The risk factors and impact of retained fetal membranes (RFM) on productive and reproductive performance of crossbred cattle, Zebu cattle, and Murrah buffalos were evaluated using data spread over 12 years. Multivariable logistic regression model was used to identify risk factors and to quantify their odds ratio (OR). Overall incidence of RFM in crossbred cattle, Zebu cattle, and Murrah buffalos were 26, 16, and 13 %, respectively; and significant risk factors for RFM in crossbred cattle were abortion (OR = 3.9), dead calf (OR = 4.1), dystocia (OR = 4.3), pluriparity (OR = 1.5), and shorter gestation length (OR = 4.3). In Zebu cattle, abortion (OR = 4.0), dead calf (OR = 3.7), dystocia (OR = 3.9), lower birth weight of calf (OR = 1.6), and shorter gestation length (OR = 6.4) were significant risk factors for RFM. In Murrah buffalos, abortion (OR = 19.2), dead calf (OR = 4.4), dystocia (OR = 4.7), pluriparity (OR = 1.7), shorter gestation length (OR = 12.7), and calving during summer season (OR = 1.8) were the risk factors for RFM. Although the occurrence of RFM did not affect fertility parameters, a significant (P < 0.05) decrease in 305-day milk yield and total milk yield was observed in RFM-affected crossbred cattle. Taken together, it may be concluded that increased parity, abnormal calving, and short gestation length were the main risk factors for RFM in dairy bovine.

  11. Tadpole swimming performance and activity affected by acute exposure to sublethal levels of carbaryl

    USGS Publications Warehouse

    Bridges, C.M.

    1997-01-01

    General activity and swimming performance (i.e., sprint speed and distance) of plains leopard frog tadpoles (Rana blairi) were examined after acute exposure to three sublethal concentrations of carbaryl (3.5, 5.0, and 7.2 mg/L). Both swimming performance and spontaneous swimming activity are important for carrying out life history functions (e.g., growth and development) and for escaping from predators. Measured tadpole activity diminished by nearly 90% at 3.5 mg/L carbaryl and completely ceased at 7.2 mg/L. Sprint speed and sprint distance also decreased significantly following exposure. Carbaryl affected both swimming performance and activity after just 24 h, suggesting that 24 h may be an adequate length of exposure to determine behavioral effects on tadpoles. Slight recovery of activity levels was noted at 24 and 48 h post-exposure; no recovery of swimming performance was observed. Reduction in activity and swimming performance may result in increased predation rates and, because activity is closely associated with feeding, may result in slowed growth leading to a failure to emerge before pond drying or an indirect reduction in adult fitness. Acute exposure to sublethal toxicants such as carbaryl may not only affect immediate survival of tadpoles but also impact critical life history functions and generate changes at the local population level.

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

    SciTech Connect

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

    2013-01-01

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

  13. Study on the separation performance of the multi-channel reduced graphene oxide membranes

    NASA Astrophysics Data System (ADS)

    Zhao, Yongjiao; Li, Chun; Fan, Xiaoyan; Wang, Jiesheng; Yuan, Guang; Song, Xinxiang; Chen, Jing; Li, Zhangde

    2016-10-01

    The multi-channel reduced graphene oxide membranes with separation function have been synthesized by a simple hydrothermal reduction method and vacuum filtration. In the as-synthesized membranes, the size, number, and type of the nanochannels can be controlled by the reduced temperature. The flux and retention rate of solution are investigated by filtering different size dye molecules. The interception and adsorption effect in the separation process are discussed. Furthermore, the sizes of the nanochannels in the membranes prepared by the different reduced temperatures are estimated. The results indicate that the multi-channel reduced graphene oxide membranes have potential application in water purification area.

  14. Influence of the semi-permeable membrane on the performance of dynamic field gradient focusing

    PubMed Central

    Burke, Jeffrey M.; Ivory, Cornelius F.

    2010-01-01

    This paper is part of our continued effort to understand the underlying principles of dynamic field gradient focusing. In this investigation, we examined three problems associated with the use of a semi-permeable membrane. First, the influence of steric and ionic exclusion of current carrying ions through the membrane was examined. It was found that resistance to the transport of ions across the membrane resulted in a shallowing of the electric field profile and an increase in the size of the defocusing zone, which is where the slope of the electric field is reversed so that it disperses rather than concentrates solutes. These problems could be reduced by using a membrane with large pores relative to the size of the buffering ions and completely void of fixed charges. Next, a numerical simulation was used to investigate concentration polarization of protein onto the surface of the membrane. Due to the presence of a transverse electric field, species were pulled toward the membrane. If the membrane is restrictive to those species, a concentrated, polarized layer will form on the surface. The simulation showed that by decreasing the channel to a depth of 20 μm, the concentrated region next to the membrane could be reduced. Finally, it was found that changes in column volume due to loss of membrane structural integrity could be mitigated by including a porous ceramic support. The variation in peak elution times was decreased from greater than 20% to less than 3%. PMID:20191552

  15. Performance and durability of carbon black-supported Pd catalyst covered with silica layers in membrane-electrode assemblies of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Fujii, Keitaro; Ito, Mizuki; Sato, Yasushi; Takenaka, Sakae; Kishida, Masahiro

    2015-04-01

    Pd metal particles supported on a high surface area carbon black (Pd/CB) were covered with silica layers to improve the durability under severe cathode condition of proton exchange membrane fuel cells (PEMFCs). The performance and the durability of the silica-coated Pd/CB (SiO2/Pd/CB) were investigated by rotating disk electrode (RDE) in aqueous HClO4 and single cell test of the membrane-electrode assemblies (MEAs). SiO2/Pd/CB showed excellent durability exceeding Pt/CB during potential cycle in single cell test as well as in RDE measurement while Pd/CB significantly degraded. Furthermore, the MEA using SiO2/Pd/CB as the cathode catalyst showed higher performance than that using Pd/CB even in the initial state. The catalytic activity of SiO2/Pd/CB was higher than that of Pd/CB, and the drop of the cell performances due to the inhibition of electron conduction, proton conduction, and oxygen diffusion by the silica layer was not significant. It has been shown that the silica-coating is a very practical technique that can stabilize metal species originally unstable in the cathode condition of PEMFCs without a decrease in the cell performance.

  16. Flexible carbon nanofiber/polyvinylidene fluoride composite membranes as interlayers in high-performance Lithiumsbnd Sulfur batteries

    NASA Astrophysics Data System (ADS)

    Wang, Zhenhua; Zhang, Jing; Yang, Yuxiang; Yue, Xinyang; Hao, Xiaoming; Sun, Wang; Rooney, David; Sun, Kening

    2016-10-01

    Traditionally polyvinylidene fluoride membranes have been used in applications such as membrane distillation, wastewater treatment, desalination and separator fabrication. Within this work we demonstrate that a novel carbon nanofiber/polyvinylidene fluoride (CNF/PVDF) composite membrane can be used as an interlayer for Lithiumsbnd Sulfur (Lisbnd S) batteries yielding both high capacity and long cycling life. This PVDF membrane is shown to effectively separate dissolved lithium polysulfide with the high electronic conductivity CNF not only reducing the internal resistance in the sulfur cathode but also helping immobilize the polysulfide through its abundant nanospaces. The resulting Lisbnd S battery assembled with the CNF/PVDF composite membrane effectively solves the polysulfide permeation problem and exhibits excellent electrochemical performance. It is further shown that the CNF/PVDF electrode has an excellent cycling stability and retains a capacity of 768.6 mAh g-1 with a coulombic efficiency above 99% over 200 cycles at 0.5C, which is more than twice that of a cell without CNF/PVDF (374 mAh g-1). In addition, the low-cost raw materials and the simple preparation process of CNF/PVDF composite membrane is also amenable for industrial production.

  17. Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane

    NASA Astrophysics Data System (ADS)

    Wahiduzzaman; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

    2017-01-01

    We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO2 and 99% N2. Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature. The MOF nanoparticles of 100-200 nm in size displayed higher surface area and adsorption capacity comparing to that of 30-60 nm in size. Nanofibrous membrane was produced by electrospinning of MOF blended PAN solution followed by electrospraying of additional MOF nanoparticles. This yielded uniform MOF deposition on nanofibers, occurred due to electrostatic attraction between highly charged nanoparticles and conductive nanofibers. A test bench for real-time CO2 adsorption at room temperature was built with non-dispersive Infrared (NDIR) CO2 sensors. Comparative tests were performed on the membrane to investigate its enhanced adsorption capacity. Three layers of the as-produced membranes displayed CO2 adsorption for approximately 2 h. Thermogravimetric analysis (TGA) of the membrane showed the thermal stability of the MOF and PAN up to 290 and 425 °C, respectively.

  18. Impact of membrane characteristics on the performance and cycling of the Br2-H2 redox flow cell

    NASA Astrophysics Data System (ADS)

    Tucker, Michael C.; Cho, Kyu Taek; Spingler, Franz B.; Weber, Adam Z.; Lin, Guangyu

    2015-06-01

    The Br2/H2 redox flow cell shows promise as a high-power, low-cost energy storage device. In this paper, the effect of various aspects of material selection and processing of proton exchange membranes on the operation of the Br2/H2 redox flow cell is determined. Membrane properties have a significant impact on the performance and efficiency of the system. In particular, there is a tradeoff between conductivity and crossover, where conductivity limits system efficiency at high current density and crossover limits efficiency at low current density. The impact of thickness, pretreatment procedure, swelling state during cell assembly, equivalent weight, membrane reinforcement, and addition of a microporous separator layer on this tradeoff is assessed. NR212 (50 μm) pretreated by soaking in 70 °C water is found to be optimal for the studied operating conditions. For this case, an energy efficiency of greater than 75% is achieved for current density up to 400 mA cm-2, with a maximum obtainable energy efficiency of 88%. A cell with this membrane was cycled continuously for 3164 h. Membrane transport properties, including conductivity and bromine and water crossover, were found to decrease moderately upon cycling but remained higher than those for the as-received membrane.

  19. Synthesis and performance of novel anion exchange membranes based on imidazolium ionic liquids for alkaline fuel cell applications

    NASA Astrophysics Data System (ADS)

    Fang, Jun; Lyu, Ming; Wang, Xin; Wu, Yongbin; Zhao, Jinbao

    2015-06-01

    Novel anion exchange membranes (AEMs) based on two types of imidazolium ionic liquids, 1-vinyl-3-methylimidazolium iodide [VMI]I and 1-vinyl-3-butylimidazolium bromide [VBI]Br, have been synthesized by copolymerization. The obtained membranes are characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal and chemical stability. The conductivity reaches 0.0226 Scm-1 at 30 °C. All the membranes show excellent thermostability. The membranes are stable in 10 mol L-1 NaOH solution at 60 °C for 120 h without obvious changes in ion conductivity. Fuel cell performance using the resulting membrane has been investigated. The open circuit voltage (OCV) of the H2/O2 fuel cell is 1.07 V. A peek power density of 116 mW cm-2 is obtained at a current density of 230 mA cm-2 at 60 °C. The results demonstrate the brilliant prospect of the developed membranes for alkaline fuel cell applications.

  20. Synthesis and performances of bio-sourced nanostructured carbon membranes elaborated by hydrothermal conversion of beer industry wastes.

    PubMed

    El Korhani, Oula; Zaouk, Doumit; Cerneaux, Sophie; Khoury, Randa; Khoury, Antonio; Cornu, David

    2013-03-07

    Hydrothermal carbonization (HTC) process of beer wastes (Almaza Brewery) yields a biochar and homogeneous carbon-based nanoparticles (NPs). The NPs have been used to prepare carbon membrane on commercial alumina support. Water filtration experiments evidenced the quasi-dense behavior of the membrane with no measurable water flux below an applied nitrogen pressure of 6 bar. Gas permeation tests were conducted and gave remarkable results, namely (1) the existence of a limit temperature of utilization of the membrane, which was below 100°C in our experimental conditions, (2) an evolution of the microstructure of the carbon membrane with the operating temperature that yielded to improved performances in gas separation, (3) the temperature-dependent gas permeance should follow a Knudsen diffusion mechanism, and (4) He permeance was increasing with the applied pressure, whereas N2 and CO2 permeances remained stable in the same conditions. These results yielded an enhancement of both the He/N2 and He/CO2 permselectivities with the applied pressure. These promising results made biomass-sourced HTC-processed carbon membranes encouraging candidates as ultralow-cost and sustainable membranes for gas separation applications.

  1. Impact of membrane characteristics on the performance and cycling of the Br₂–H₂ redox flow cell

    SciTech Connect

    Tucker, Michael C.; Cho, Kyu Taek; Spingler, Franz B.; Weber, Adam Z.; Lin, Guangyu

    2015-03-04

    The Br₂/H₂ redox flow cell shows promise as a high-power, low-cost energy storage device. In this paper, the effect of various aspects of material selection and processing of proton exchange membranes on the operation of the Br₂/H₂ redox flow cell is determined. Membrane properties have a significant impact on the performance and efficiency of the system. In particular, there is a tradeoff between conductivity and crossover, where conductivity limits system efficiency at high current density and crossover limits efficiency at low current density. The impact of thickness, pretreatment procedure, swelling state during cell assembly, equivalent weight, membrane reinforcement, and addition of a microporous separator layer on this tradeoff is assessed. NR212 (50 μm) pretreated by soaking in 70 °C water is found to be optimal for the studied operating conditions. For this case, an energy efficiency of greater than 75% is achieved for current density up to 400 mA cm⁻², with a maximum obtainable energy efficiency of 88%. A cell with this membrane was cycled continuously for 3164 h. Membrane transport properties, including conductivity and bromine and water crossover, were found to decrease moderately upon cycling but remained higher than those for the as-received membrane.

  2. Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane.

    PubMed

    Wahiduzzaman; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

    2017-12-01

    We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO2 and 99% N2. Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature. The MOF nanoparticles of 100-200 nm in size displayed higher surface area and adsorption capacity comparing to that of 30-60 nm in size. Nanofibrous membrane was produced by electrospinning of MOF blended PAN solution followed by electrospraying of additional MOF nanoparticles. This yielded uniform MOF deposition on nanofibers, occurred due to electrostatic attraction between highly charged nanoparticles and conductive nanofibers. A test bench for real-time CO2 adsorption at room temperature was built with non-dispersive Infrared (NDIR) CO2 sensors. Comparative tests were performed on the membrane to investigate its enhanced adsorption capacity. Three layers of the as-produced membranes displayed CO2 adsorption for approximately 2 h. Thermogravimetric analysis (TGA) of the membrane showed the thermal stability of the MOF and PAN up to 290 and 425 °C, respectively.

  3. Impact of membrane characteristics on the performance and cycling of the Br-2-H-2 redox flow cell

    SciTech Connect

    Tucker, MC; Cho, KT; Spingler, FB; Weber, AZ; Lin, GY

    2015-06-15

    The Br-2/H-2 redox flow cell shows promise as a high-power, low-cost energy storage device. In this paper, the effect of various aspects of material selection and processing of proton exchange membranes on the operation of the Br-2/H-2 redox flow cell is determined. Membrane properties have a significant impact on the performance and efficiency of the system. In particular, there is a tradeoff between conductivity and crossover, where conductivity limits system efficiency at high current density and crossover limits efficiency at low current density. The impact of thickness, pretreatment procedure, swelling state during cell assembly, equivalent weight, membrane reinforcement, and addition of a microporous separator layer on this tradeoff is assessed. NR212 (50 mu m) pretreated by soaking in 70 degrees C water is found to be optimal for the studied operating conditions. For this case, an energy efficiency of greater than 75% is achieved for current density up to 400 mA cm(-2), with a maximum obtainable energy efficiency of 88%. A cell with this membrane was cycled continuously for 3164 h. Membrane transport properties, including conductivity and bromine and water crossover, were found to decrease moderately upon cycling but remained higher than those for the as-received membrane. (C) 2015 Elsevier B.V. All rights reserved.

  4. Impact of membrane characteristics on the performance and cycling of the Br₂–H₂ redox flow cell

    DOE PAGES

    Tucker, Michael C.; Cho, Kyu Taek; Spingler, Franz B.; ...

    2015-03-04

    The Br₂/H₂ redox flow cell shows promise as a high-power, low-cost energy storage device. In this paper, the effect of various aspects of material selection and processing of proton exchange membranes on the operation of the Br₂/H₂ redox flow cell is determined. Membrane properties have a significant impact on the performance and efficiency of the system. In particular, there is a tradeoff between conductivity and crossover, where conductivity limits system efficiency at high current density and crossover limits efficiency at low current density. The impact of thickness, pretreatment procedure, swelling state during cell assembly, equivalent weight, membrane reinforcement, and additionmore » of a microporous separator layer on this tradeoff is assessed. NR212 (50 μm) pretreated by soaking in 70 °C water is found to be optimal for the studied operating conditions. For this case, an energy efficiency of greater than 75% is achieved for current density up to 400 mA cm⁻², with a maximum obtainable energy efficiency of 88%. A cell with this membrane was cycled continuously for 3164 h. Membrane transport properties, including conductivity and bromine and water crossover, were found to decrease moderately upon cycling but remained higher than those for the as-received membrane.« less

  5. Synthesis and performances of bio-sourced nanostructured carbon membranes elaborated by hydrothermal conversion of beer industry wastes

    PubMed Central

    2013-01-01

    Hydrothermal carbonization (HTC) process of beer wastes (Almaza Brewery) yields a biochar and homogeneous carbon-based nanoparticles (NPs). The NPs have been used to prepare carbon membrane on commercial alumina support. Water filtration experiments evidenced the quasi-dense behavior of the membrane with no measurable water flux below an applied nitrogen pressure of 6 bar. Gas permeation tests were conducted and gave remarkable results, namely (1) the existence of a limit temperature of utilization of the membrane, which was below 100°C in our experimental conditions, (2) an evolution of the microstructure of the carbon membrane with the operating temperature that yielded to improved performances in gas separation, (3) the temperature-dependent gas permeance should follow a Knudsen diffusion mechanism, and (4) He permeance was increasing with the applied pressure, whereas N2 and CO2 permeances remained stable in the same conditions. These results yielded an enhancement of both the He/N2 and He/CO2 permselectivities with the applied pressure. These promising results made biomass-sourced HTC-processed carbon membranes encouraging candidates as ultralow-cost and sustainable membranes for gas separation applications. PMID:23497215

  6. Synthesis and performances of bio-sourced nanostructured carbon membranes elaborated by hydrothermal conversion of beer industry wastes

    NASA Astrophysics Data System (ADS)

    El Korhani, Oula; Zaouk, Doumit; Cerneaux, Sophie; Khoury, Randa; Khoury, Antonio; Cornu, David

    2013-03-01

    Hydrothermal carbonization (HTC) process of beer wastes (Almaza Brewery) yields a biochar and homogeneous carbon-based nanoparticles (NPs). The NPs have been used to prepare carbon membrane on commercial alumina support. Water filtration experiments evidenced the quasi-dense behavior of the membrane with no measurable water flux below an applied nitrogen pressure of 6 bar. Gas permeation tests were conducted and gave remarkable results, namely (1) the existence of a limit temperature of utilization of the membrane, which was below 100°C in our experimental conditions, (2) an evolution of the microstructure of the carbon membrane with the operating temperature that yielded to improved performances in gas separation, (3) the temperature-dependent gas permeance should follow a Knudsen diffusion mechanism, and (4) He permeance was increasing with the applied pressure, whereas N2 and CO2 permeances remained stable in the same conditions. These results yielded an enhancement of both the He/N2 and He/CO2 permselectivities with the applied pressure. These promising results made biomass-sourced HTC-processed carbon membranes encouraging candidates as ultralow-cost and sustainable membranes for gas separation applications.

  7. Imp2, the PSTPIP homolog in fission yeast, affects sensitivity to the immunosuppressant FK506 and membrane trafficking in fission yeast

    SciTech Connect

    Kita, Ayako; Higa, Mari; Doi, Akira; Satoh, Ryosuke; Sugiura, Reiko

    2015-02-13

    Cytokinesis is a highly ordered process that divides one cell into two cells, which is functionally linked to the dynamic remodeling of the plasma membrane coordinately with various events such as membrane trafficking. Calcineurin is a highly conserved serine/threonine protein phosphatase, which regulates multiple biological functions, such as membrane trafficking and cytokinesis. Here, we isolated imp2-c3, a mutant allele of the imp2{sup +} gene, encoding a homolog of the mouse PSTPIP1 (proline-serine-threonine phosphatase interacting protein 1), using a genetic screen for mutations that are synthetically lethal with calcineurin deletion in fission yeast. The imp2-c3 mutants showed a defect in cytokinesis with multi-septated phenotypes, which was further enhanced upon treatment with the calcineurin inhibitor FK506. Notably, electron micrographs revealed that the imp2-c3 mutant cells accumulated aberrant multi-lamella Golgi structures and putative post-Golgi secretory vesicles, and exhibited fragmented vacuoles in addition to thickened septa. Consistently, imp2-c3 mutants showed a reduced secretion of acid phosphatase and defects in vacuole fusion. The imp2-c3 mutant cells exhibited a weakened cell wall, similar to the membrane trafficking mutants identified in the same genetic screen such as ypt3-i5. These findings implicate the PSTPIP1 homolog Imp2 in Golgi/vacuole function, thereby affecting various cellular processes, including cytokinesis and cell integrity. - Highlights: • We isolated imp2-c3, in a synthetic lethal screen with calcineurin in fission yeast. • The imp2{sup +} gene encodes a component of the actin contractile ring similar to Cdc15. • The imp2-c3 mutants showed defects in cytokinesis, which were exacerbated by FK506. • The imp2-c3 mutants were defective in membrane trafficking and cell wall integrity. • Our study revealed a novel role for Imp2 in the Golgi/vacuolar membrane trafficking.

  8. Surface patterning of polymeric separation membranes and its influence on the filtration performance

    NASA Astrophysics Data System (ADS)

    Maruf, Sajjad

    Polymeric membrane based separation technologies are crucial for addressing the global issues such as water purification. However, continuous operations of these processes are often hindered by fouling which increases mass transport resistance of the membrane to permeation and thus the energy cost, and eventually replacement of the membrane in the system. In comparison to other anti-fouling strategies, the use of controlled surface topography to mitigate fouling has not been realized mainly due to the lack of methods to create targeted topography on the porous membrane surface. This thesis aims to develop a new methodology to create surface-patterned polymeric separation membrane to improve their anti-fouling characteristics during filtration. First, successful fabrication of sub-micron surface patterns directly on a commercial ultrafiltration (UF) membrane surface using nanoimprint lithographic (NIL) technique was demonstrated. Comprehensive filtration studies revealed that the presence of these sub-micron surface patterns mitigates not only the onset of colloidal particle deposition, but also lowers the rate of growth of cake layer after initial deposition, in comparison with un-patterned membranes. The anti-fouling effects were also observed for model protein solutions. Staged filtration experiments, with backwash cleaning, revealed that the permeate flux of the patterned membrane after protein fouling was considerably higher than that of the pristine or un-patterned membrane. In addition to the surface-patterning of UF membranes, successful fabrication of a surface-patterned thin film composite (TFC) membrane was shown for the first time. A two-step fabrication process was carried out by (1) nanoimprinting a polyethersulfone (PES) support using NIL, and (2) forming a thin dense film atop the PES support via interfacial polymerization (IP). Fouling experiments suggest that the surface patterns alter the hydrodynamics at the membrane-feed interface, which is

  9. An ultrasensitive bio-surrogate for nanoporous filter membrane performance metrology directed towards contamination control in microlithography applications

    NASA Astrophysics Data System (ADS)

    Ahmad, Farhan; Mish, Barbara; Qiu, Jian; Singh, Amarnauth; Varanasi, Rao; Bedford, Eilidh; Smith, Martin

    2016-03-01

    Contamination tolerances in semiconductor manufacturing processes have changed dramatically in the past two decades, reaching below 20 nm according to the guidelines of the International Technology Roadmap for Semiconductors. The move to narrower line widths drives the need for innovative filtration technologies that can achieve higher particle/contaminant removal performance resulting in cleaner process fluids. Nanoporous filter membrane metrology tools that have been the workhorse over the past decade are also now reaching limits. For example, nanoparticle (NP) challenge testing is commonly applied for assessing particle retention performance of filter membranes. Factors such as high NP size dispersity, low NP detection sensitivity, and high NP particle-filter affinity impose challenges in characterizing the next generation of nanoporous filter membranes. We report a novel bio-surrogate, 5 nm DNA-dendrimer conjugate for evaluating particle retention performance of nanoporous filter membranes. A technique capable of single molecule detection is employed to detect sparse concentration of conjugate in filter permeate, providing >1000- fold higher detection sensitivity than any existing 5 nm-sized particle enumeration technique. This bio-surrogate also offers narrow size distribution, high stability and chemical tunability. This bio-surrogate can discriminate various sub-15 nm pore-rated nanoporous filter membranes based on their particle retention performance. Due to high bio-surrogate detection sensitivity, a lower challenge concentration of bio-surrogate (as compared to other NPs of this size) can be used for filter testing, providing a better representation of customer applications. This new method should provide better understanding of the next generation filter membranes for removing defect-causing contaminants from lithography processes.

  10. Preparation of Polyvinylidene Fluoride (PVDF) Hollow Fiber Hemodialysis Membranes.

    PubMed

    Zhang, Qinglei; Lu, Xiaolong; Zhao, Lihua

    2014-02-27

    In this study, the polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS). The influences of PVDF membrane thickness and polyethylene glycol (PEG) content on membrane morphologies, pore size, mechanical and permeable performance were investigated. It was found that membrane thickness and PEG content affected both the structure and performance of hollow fiber membranes. The tensile strength and rejection of bovine serum albumin (BSA) increased with increasing membrane thickness, while the Ultrafiltration flux (UF) flux of pure water was the opposite. The tensile strength, porosity and rejection of BSA increased with increasing PEG content within a certain range. Compared with commercial F60S membrane, the PVDF hollow fiber membrane showed higher mechanical and permeable performance. It was proven that PVDF material had better hydrophilicity and lower BSA adsorption, which was more suitable for hemodialysis. All the results indicate that PVDF hollow fiber membrane is promising as a hemodialysis membrane.

  11. The absence of myristic acid decreases membrane binding of p60src but does not affect tyrosine protein kinase activity.

    PubMed Central

    Buss, J E; Kamps, M P; Gould, K; Sefton, B M

    1986-01-01

    We have constructed two point mutants of Rous sarcoma virus in which the amino-terminal glycine residue of the transforming protein, p60src, was changed to an alanine or a glutamic acid residue. Both mutant proteins failed to become myristylated and, more importantly, no longer transformed cells. The lack of transformation could not be attributed to defects in the catalytic activity of the mutant p60src proteins. In vitro phosphorylation of the peptide angiotensin or of the cellular substrate proteins enolase and p36 revealed no significant differences in the Km or specific activity of the mutant and wild-type p60src proteins. However, when cellular fractions were prepared, less than 12% of the nonmyristylated p60src proteins was bound to membranes. In contrast, more than 82% of the wild-type protein was associated with membranes. Wild-type p60src was phosphorylated by protein kinase C, a protein kinase which associates with membranes when activated. The mutant proteins were not. This finding supports the idea that within the intact cell the nonmyristylated p60src proteins are cytoplasmic and suggests that this apparent solubility is not an artifact of the cell fractionation procedure. The myristyl groups of p60src apparently encourages a tight association between protein and membranes and, by determining the cellular location of the enzyme, allows transformation to occur. Images PMID:3009860

  12. Removal from the membrane affects the interaction of rat osseous plate ecto-nucleosidetriphosphate diphosphohydrolase-1 with substrates and ions.

    PubMed

    Garçon, Daniela P; Masui, Douglas C; Furriel, Rosa P M; Leone, Francisco A

    2008-01-01

    We have characterized the kinetic properties of ectonucleoside triphosphate diphosphohydrolase 1 (E-NTPDase1) from rat osseous plate membranes. A novel finding of the present study is that the solubilized enzyme shows high- and low-affinity sites for the substrate in contrast with a single substrate site for the membrane-bound enzyme. In addition, contrary to the Michaelian chraracteristics of the membrane-bound enzyme, the site-site interactions after solubilization with 0.5% digitonin plus 0.1% lysolecithin resulted in a less active ectonucleoside triphosphate diphosphohydrolase, showing activity of about 398.3 nmol Pi min(-1) mg(-1). The solubilized enzyme has M (r) of 66-72 kDa, and its catalytic efficiency was significantly increased by magnesium and calcium ions; but the ATP/ADP activity ratio was always <2.0. Partial purification and kinetic characterization of the rat osseous plate E-NTPDase1 in a solubilized form may lead to a better understanding of a possible function of the enzyme as a modulator of nucleotidase activity or purinergic signaling in matrix vesicle membranes. The simple procedure to obtain the enzyme in a solubilized form may also be attractive for comparative studies of particular features of the active sites from this and other ATPases.

  13. Influence of sludge retention time at constant food to microorganisms ratio on membrane bioreactor performances under stable and unstable state conditions.

    PubMed

    Villain, Maud; Marrot, Benoît

    2013-01-01

    Food to microorganisms ratio (F/M) and sludge retention time (SRT) are known to affect in different ways biomass growth, bioactivities and foulants characteristics. Thus the aim of this study was to dissociate the effects of SRT from those of F/M ratio on lab-scale membrane bioreactors performances during stable and unstable state. Two acclimations were stabilized at a SRT of either 20 or 50 d with a constant F/M ratio of 0.2 kg(COD)kg(MLVSS)(-1) d(-1). During stable state, a higher N-NH(4)(+) removal rate (78%) was obtained at SRT of 50 d as an easier autotroph development was observed. Soluble microbial products (SMPs) release was double at 50 d with a majority of polysaccharides (49% of total SMP). The unstable conditions consisted in F/M ratio changes and operation without air and nutrient. Autotrophs were highly affected by the tested disturbances and SMP retention on membrane surface exhibited consistent changes during the performed stresses.

  14. Nutritional effects of egg shell membrane supplements on chicken performance and immunity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eggshell membranes (ESM) contain a variety of proteins and peptides which help in the development of embryo and provide protection to it. Many of the peptides and proteins associated with ESM have antimicrobial, immune-modulatory, and adjuvant properties. We hypothesized that the membrane byproducts...

  15. Performances of nanofiltration and low pressure reverse osmosis membranes for desalination: characterization and modelling

    NASA Astrophysics Data System (ADS)

    Boussouga, Y. A.; Lhassani, A.

    2017-03-01

    The nanofiltration and the reverse osmosis processes are the most common techniques for the desalination of water contaminated by an excess of salts. In this present study, we were interested in the characterization of commercial, composite and asymmetric membranes of nanofiltration (NF90, NF270) and low pressure reverse osmosis (BW30LE). The two types of characterization that we opted for our study: (i) characterization of electrical proprieties, in terms of the surface charge of various membranes studied by the measurement of the streaming potential, (ii) hydrodynamic characterization in terms of hydraulic permeability with pure water, mass transfer and phenomenological parameters for each system membrane/salt using hydrodynamic approaches. The irreversible thermodynamics allowed us to model the observed retention Robs of salts (NaCl and Na2SO4) for the different membranes studied, to understand and to predict a good filtration with a membrane. A study was conducted on the type of mass transfer for each system membrane/salt: convection and diffusion. The results showed that all tested membranes are negatively charged for the solutions at neutral pH, this is explained by their material composition. The results also showed competitiveness between the different types of membranes. In view of that the NF remains effective in terms of selective retention with less energy consumption than LPRO.

  16. Executive dysfunction affects word list recall performance: Evidence from amyotrophic lateral sclerosis and other neurodegenerative diseases.

    PubMed

    Consonni, Monica; Rossi, Stefania; Cerami, Chiara; Marcone, Alessandra; Iannaccone, Sandro; Francesco Cappa, Stefano; Perani, Daniela

    2017-03-01

    The Rey Auditory Verbal Learning Test (RAVLT) is widely used in clinical practice to evaluate verbal episodic memory. While there is evidence that RAVLT performance can be influenced by executive dysfunction, the way executive disorders affect the serial position curve (SPC) has not been yet explored. To this aim, we analysed immediate and delayed recall performances of 13 non-demented amyotrophic lateral sclerosis (ALS) patients with a specific mild executive dysfunction (ALSci) and compared their performances to those of 48 healthy controls (HC) and 13 cognitively normal patients with ALS. Moreover, to control for the impact of a severe dysexecutive syndrome and a genuine episodic memory deficit on the SPC, we enrolled 15 patients with a diagnosis of behavioural variant of frontotemporal dementia (bvFTD) and 18 patients with probable Alzheimer's disease (AD). Results documented that, compared to cognitively normal subjects, ALSci patients had a selective mid-list impairment for immediate recall scores. The bvFTD group obtained low performances with a selectively increased forgetting rate for terminal items, whereas the AD group showed a disproportionately large memory loss on the primary and middle part of the SPC for immediate recall scores and were severely impaired in the delayed recall trial. These results suggested that subtle executive dysfunctions might influence the recall of mid-list items, possibly reflecting deficiency in control strategies at retrieval of word lists, whereas severer dysexecutive syndrome might also affect the recall of terminal items possibly due to attention deficit or retroactive interference.

  17. Neural Efficiency in Expert Cognitive-Motor Performers During Affective Challenge.

    PubMed

    Costanzo, Michelle E; VanMeter, John W; Janelle, Christopher M; Braun, Allen; Miller, Matthew W; Oldham, Jessica; Russell, Bartlett A H; Hatfield, Bradley D

    2016-01-01

    Skilled individuals demonstrate a spatially localized or relatively lower response in brain activity characterized as neural efficiency when performing within their domain of expertise. Elite athletes are experts in their chosen sport and thus must be not only adept in the motor domain but must be resilient to performing under the stress of high-level competition. Such stability of performance suggests this population processes emotion and mental stress in an adaptive and efficient manner. This study sought to determine if athletes with a history of successful performance under circumstances of mental stress demonstrate neural efficiency during affective challenges compared to age-matched controls. Using functional magnetic resonance imaging, the blood-oxygen level-dependent response was recorded during emotional challenge induced by sport-specific and general unpleasant images. The athletes demonstrated neural efficiency in brain regions critical to emotion regulation (prefrontal cortex) and affect (insula) independently of their domain of expertise, suggesting adaptive processing of negative events and less emotional reactivity to unpleasant stimuli.

  18. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Analysis of Factors Affecting Its Performance

    NASA Technical Reports Server (NTRS)

    Perry, Bruce A.; Anderson, Molly S.

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station Water Processor Assembly to form a complete water recovery system for future missions. A preliminary chemical process simulation was previously developed using Aspen Custom Modeler® (ACM), but it could not simulate thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. This paper describes modifications to the ACM simulation of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version can be used to model thermal startup and predicts the total energy consumption of the CDS. The simulation has been validated for both NaC1 solution and pretreated urine feeds and no longer requires retuning when operating parameters change. The simulation was also used to predict how internal processes and operating conditions of the CDS affect its performance. In particular, it is shown that the coefficient of performance of the thermoelectric heat pump used to provide heating and cooling for the CDS is the largest factor in determining CDS efficiency. Intrastage heat transfer affects CDS performance indirectly through effects on the coefficient of performance.

  19. High-performance multilayer composite membranes with mussel-inspired polydopamine as a versatile molecular bridge for CO2 separation.

    PubMed

    Li, Panyuan; Wang, Zhi; Li, Wen; Liu, Yanni; Wang, Jixiao; Wang, Shichang

    2015-07-22

    It is desirable to develop high-performance composite membranes for efficient CO2 separation in CO2 capture process. Introduction of a highly permeable polydimethylsiloxane (PDMS) intermediate layer between a selective layer and a porous support has been considered as a simple but efficient way to enhance gas permeance while maintaining high gas selectivity, because the introduced intermediate layer could benefit the formation of an ultrathin defect-free selective layer owing to the circumvention of pore penetration phenomenon. However, the selection of selective layer materials is unfavorably restricted because of the low surface energy of PDMS. Various highly hydrophilic membrane materials such as amino group-rich polyvinylamine (PVAm), a representative facilitated transport membrane material for CO2 separation, could not be facilely coated over the surface of the hydrophobic PDMS intermediate layer uniformly. Inspired by the hydrophilic nature and strong adhesive ability of polydopamine (PDA), PDA was therefore selected as a versatile molecular bridge between hydrophobic PDMS and hydrophilic PVAm. The PDA coating endows a highly compatible interface between both components with a large surface energy difference via multiple-site cooperative interactions. The resulting multilayer composite membrane with a thin facilitated transport PVAm selective layer exhibits a notably enhanced CO2 permeance (1887 GPU) combi