Science.gov

Sample records for semi-permeable membrane devices

  1. Development of bioassay techniques with extracts from semi-permeable membrane devices (SPMDs)

    SciTech Connect

    Metcalfe, T.L.; White, P.; Mackay, D.; Metcalfe, C.

    1995-12-31

    Semi-permeable membrane devices (SPMDs), consisting of polyethylene bags filled with triolein, have been used to monitor for lipophilic organic contaminants in water. Although extracts from SPMDs have most often been analyzed for concentrations of organic contaminants, there is also the potential to monitor the toxicity of these extracts using in vitro and in vivo bioassays. SPMDs were deployed for four weeks at several sites along a corridor extending from Peche Island in the Detroit River to Pelee Island in western Lake Erie to monitor the distribution of toxic organic contaminants in the water. Analysis of the extracts from the SPMDs for concentrations of PCBs and other organochlorine compounds, and polynuclear aromatic hydrocarbons (PAHs) indicated that the regions in the Detroit River within the Trenton Channel and near Zug Island were the most highly contaminated. Bioassays conducted with extracts from the SPMDs included the in vitro SOS Chromotest for genotoxic activity, an acute lethality test with Daphnia magna, and a fish embryotoxicity test with embryos of Japanese medaka (Oryzias latipes). These bioassay data generally indicated that the toxicity and concentrations of organic contaminants in the SPMD extracts were correlated. This study indicates that there is potential to use short-term bioassays of extracts from SPMDs to monitor for in situ contamination in the aquatic environment.

  2. USE OF SEMI-PERMEABLE MEMBRANE DEVICES TO MONITOR POLLUTANTS IN WATER AND ASSESS THEIR EFFECTS: A LABORATORY TEST AND FIELD VERIFICATION. (U915464)

    EPA Science Inventory

    Uptake of eight pesticides of different classes (organochlorines, synthetic pyrethroids, dinitroanilines, amides) by semi-permeable membrane devices (SPMDs) was studied in a laboratory continuous-flow system. After 20 days of exposure, membrane concentration factors were in th...

  3. Persistent Organic Pollutants in Semi-permeable Membrane Devices (SPMDs) Deployed in the Ambient Air of Alaska

    NASA Astrophysics Data System (ADS)

    Wu, T. H.; Cahill, C. F.

    2005-12-01

    Triolein containing semi-permeable membrane devices (SPMDs) were deployed in the ambient air of Alaska at five locations (Barrow, Poker Flat Research Range, Denali National Park and Preserve, Trapper Creek and Homer) during a one year study. Samples were screened for polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and organochlorine compounds (OCPs). Total PCBs ranged from 5-30 ng/SPMD for three-month time-integrated samples. Measurements of selected PAH ratios suggest mixed sources (petrogenic and pyrogenic) at the five locations. The percent ratio of pp-DDT [1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane] to total DDT (DDT and all metabolites) ranged from 17-66%. A higher percentage may indicate the presence of a fresh input of DDT into the atmosphere or non-metabolized DDT that has remained in the environment. Ratio of trans-chlordane (TC) to cis-chlordane (CC) varied from 0.7-1.2. Higher ratios of TC to CC may indicate fresh input into Alaska from various source regions during deployment of SPMDs.

  4. An analysis of using semi-permeable membrane devices to assess persistent organic pollutants in ambient air of Alaska

    NASA Astrophysics Data System (ADS)

    Wu, Ted Hsin-Yeh

    A region of concern for persistent organic pollutants (POPS) contamination is the Arctic, because of POPs' ability to migrate long distances through the atmosphere toward cold regions, condense out of the atmosphere in those region, deposit in sensitive arctic ecosystems and bioaccumulate in Arctic species. Thus, monitoring of POP concentrations in the Arctic is necessary. However, traditional active air monitoring techniques for POPs may not be feasible in the Arctic, because of logistics and cost. While these issues may be overcome using passive air sampling devices, questions arise about the interpretation of the contaminant concentrations detected using the passive air samplers. In this dissertation semi-permeable membrane devices (SPMDs) containing triolein were characterized and evaluated for use in sampling the ambient air of Alaska for three classes of POPS (organochlorines [OCs], polychlorinated biphenyls [PCBs] and polyaromatic hydrocarbons [PAHs]). In addition, a SPMD-based sampling campaign for POPS was conducted simultaneously at five sites in Alaska during a one-year period. The POP concentrations obtained from the SPMDs were examined to determine the spatial and seasonal variability at the locations. POP concentrations detected in SPMDs were influenced by exposure to sunlight, concentrations of particulate-bound contaminants and changes in temperature. PAH concentrations in a SPMD mounted in a sunlight-blocking deployment unit were higher than in a SPMD exposed to sunlight (P = 0.007). PCB concentrations in SPMD exposed to filtered and non-filtered air were significantly different (P < 0.0001). Derived PAH air concentrations measured using SPMD were within a factor of approximately 7 of those obtained from an air sampler in Barrow, Alaska. The field study showed three distinct groups of samples. Barrow was separated from the sub-Arctic samples and a Homer sample (September-December) was distinct from the sub-Arctic samples. The separations suggest

  5. Using semi-permeable membrane devices and stable nitrogen isotopes to detect anthropogenic influences on the Truckee River, USA

    USGS Publications Warehouse

    Saito, L.; Rosen, Michael R.; Chandra, S.; Fritsen, C.H.; Arufe, J.A.; Redd, C.

    2008-01-01

    Stable nitrogen isotopes (??15N) and semipermeable membrane devices (SPMDs) were used together to provide evidence of potential anthropogenic connections to aquatic organisms in the Truckee River, which flows through the Reno/Sparks metropolitan area in Nevada. Crayfish, snail, and periphyton ??15N values, and SPMD toxicity data collected during high and low flow periods at seven primary sites on the river were used with water quality and flow data for the assessment. All biota showed an increase of ??15N on both dates at sites downstream of inflows of a water-quality impaired tributary and urban drain relative to upstream. In addition, most of the lowest ??15N values on each date occurred at the most downstream site on the river. SPMDs sample lipophilic organic contaminants and can be used to assess organic contaminant toxicity to aquatic organisms because they use a membrane that mimics organic contaminant uptake by fish. In this study, results from a fluoroscan test [pyrene index (PI)] of SPMD extracts that responds to higher molecular weight polycyclic aromatic hydrocarbons (PAHs) showed patterns similar to stable isotope data, although observed peaks in PI values occurred in the urban area upstream of where peak ??15N values occurred. The CYP1A biomarker test, which responds to PAHs, certain polychlorinated biphenyls (PCBs), and organochlorines, showed peak toxic equivalents (TEQ) values farther downstream of the urban area. Thus, it is likely that PAHs were contributing to toxicity in the urban area, whereas other nonurban sources of organic carbon may have been present farther downstream. The combined use of stable isotope measurements and SPMDs provided a means of simultaneously examining whether aquatic biota are incorporating constituents from potential food sources (via stable isotopes) or exposure through water (via SPMDs). ?? Mary Ann Liebert, Inc. 2008.

  6. PAH assessment in the main Brazilian offshore oil and gas production area using semi-permeable membrane devices (SPMD) and transplanted bivalves

    NASA Astrophysics Data System (ADS)

    André Lourenço, Rafael; Francisco de Oliveira, Fábio; Haddad Nudi, Adriana; Rebello Wagener, Ângela de Luca; Guadalupe Meniconi, Maria de Fátima; Francioni, Eleine

    2015-06-01

    The Campos Basin is Brazil's main oil and gas production area. In 2013, more than 50 million cubic meters of produced water (PW) was discharged into these offshore waters. Despite the large volumes of PW that are discharged in the Campos Basin each day, the ecological concern of the chemicals in the PW are not completely understood. Polycyclic aromatic hydrocarbons (PAH) are the most important contributors to the ecological hazards that are posed by discharged PW. This study aimed to evaluate the potential bioaccumulation of PAH using transplanted bivalves (Nodipecten nodosus) and semi-permeable membrane devices (SPMD). The study was conducted in two platforms that discharge PW (P19 and P40). Another platform that does not discharge PW (P25) was investigated for comparison with the obtained results. Time-integrated hydrocarbon concentrations using SPMD and transplanted bivalves were estimated from the seawater near the three platforms. The bioaccumulation of the PAH in the transplanted bivalves at platforms P19 and P40 were up to fivefold greater than the bioaccumulation of the PAH at platform P25. The lowest PAH concentrations were estimated for platform P25 (4.3-6.2 ng L-1), and the highest PAH concentrations were estimated for platform P19 (9.2-37.3 ng L-1). Both techniques were effective for determining the bioavailability of the PAH and for providing time-integrated hydrocarbon concentrations regarding oil and gas production activities.

  7. Electrostatic interaction of neutral semi-permeable membranes

    NASA Astrophysics Data System (ADS)

    Vinogradova, Olga I.; Bocquet, Lyderic; Bogdanov, Artem N.; Tsekov, Roumen; Lobaskin, Vladimir

    2012-01-01

    We consider an osmotic equilibrium between bulk solutions of polyelectrolyte bounded by semi-permeable membranes and separated by a thin film of salt-free liquid. Although the membranes are neutral, the counter-ions of the polyelectrolyte molecules permeate into the gap and lead to a steric charge separation. This gives rise to a distance-dependent membrane potential, which translates into a repulsive electrostatic disjoining pressure. From the solution of the nonlinear Poisson-Boltzmann equation, we obtain the distribution of the potential and of ions. We then derive an explicit formula for the pressure exerted on the membranes and show that it deviates from the classical van't Hoff expression for the osmotic pressure. This difference is interpreted in terms of a repulsive electrostatic disjoining pressure originating from the overlap of counterion clouds inside the gap. We also develop a simplified theory based on a linearized Poisson-Boltzmann approach. A comparison with simulation of a primitive model for the electrolyte is provided and does confirm the validity of the theoretical predictions. Beyond the fundamental result that the neutral surfaces can repel, this mechanism not only helps to control the adhesion and long-range interactions of living cells, bacteria, and vesicles, but also allows us to argue that electrostatic interactions should play enormous role in determining behavior and functions of systems bounded by semi-permeable membranes.

  8. Algae Bioreactor Using Submerged Enclosures with Semi-Permeable Membranes

    NASA Technical Reports Server (NTRS)

    Trent, Jonathan D (Inventor); Gormly, Sherwin J (Inventor); Embaye, Tsegereda N (Inventor); Delzeit, Lance D (Inventor); Flynn, Michael T (Inventor); Liggett, Travis A (Inventor); Buckwalter, Patrick W (Inventor); Baertsch, Robert (Inventor)

    2013-01-01

    Methods for producing hydrocarbons, including oil, by processing algae and/or other micro-organisms in an aquatic environment. Flexible bags (e.g., plastic) with CO.sub.2/O.sub.2 exchange membranes, suspended at a controllable depth in a first liquid (e.g., seawater), receive a second liquid (e.g., liquid effluent from a "dead zone") containing seeds for algae growth. The algae are cultivated and harvested in the bags, after most of the second liquid is removed by forward osmosis through liquid exchange membranes. The algae are removed and processed, and the bags are cleaned and reused.

  9. The casting and mechanism of formation of semi-permeable polymer membranes in a microgravity environment

    NASA Astrophysics Data System (ADS)

    Vera, I.

    The National Electric Company of Venezuela, C.A.D.A.F.E., is sponsoring the development of this experiment which represents Venezuela's first scientific experiment in space. The apparatus for the automatic casting of polymer thin films will be contained in NASA's payload No. G-559 of the Get Away Special program for a future orbital space flight in the U.S. Space Shuttle. Semi-permeable polymer membranes have important applications in a variety of fields, such as medecine, energy, and pharmaceuticals, and in general fluid separation processes such as reverse osmosis, ultra-filtration, and electro-dialysis. The casting of semi-permeable membranes in space will help to identify the roles of convection in determining the strucutre of these membranes.

  10. 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

  11. Seasonal Assessment of Biomass and Fatty Acid Productivity by Tetraselmis sp. in the Ocean Using Semi-Permeable Membrane Photobioreactors.

    PubMed

    Kim, Z-Hun; Park, Hanwool; Lee, Choul-Gyun

    2016-06-28

    A green microalga, Tetraselmis sp., was cultivated in the coastal seawater of Young-Heung Island using semi-permeable membrane photobioreactors (SPM-PBRs) in different seasons. The microalgae in the SPM-PBRs were able to grow on nutrients diffused into the PBRs from the surrounding seawater through SPMs. The biomass productivity varied depending on the ion permeabilities of the SPMs and environmental conditions, whereas the quality and quantity of fatty acids were constant. The temperature of seawater had a greater influence than solar radiation did on productivity of Tetraselmis sp. in SPM-PBRs. SPM-PBRs could provide technologies for concurrent algal biomass and fatty acids production, and eutrophication reduction in the ocean. PMID:26975763

  12. Semi-Permeable Membrane Retention of Synovial Fluid Lubricants Hyaluronan and Proteoglycan 4 for a Biomimetic Bioreactor

    PubMed Central

    Blewis, Megan E.; Lao, Brian J.; Jadin, Kyle D.; McCarty, William J.; Bugbee, William D.; Firestein, Gary S.

    2010-01-01

    Synovial fluid (SF) contains lubricant macromolecules, hyaluronan (HA), and proteoglycan 4 (PRG4). The synovium not only contributes lubricants to SF through secretion by synoviocyte lining cells, but also concentrates lubricants in SF due to its semi-permeable nature. A membrane that recapitulates these synovium functions may be useful in a bioreactor system for generating a bioengineered fluid (BF) similar to native SF. The objectives were to analyze expanded polytetrafluoroethylene membranes with pore sizes of 50 nm, 90 nm, 170 nm, and 3 μm in terms of (1) HA and PRG4 secretion rates by adherent synoviocytes, and (2) the extent of HA and PRG4 retention with or without synoviocytes adherent on the membrane. Experiment 1: Synoviocytes were cultured on tissue culture (TC) plastic or membranes ± IL-1β + TGF-β1 + TNF-α, a cytokine combination that stimulates lubricant synthesis. HA and PRG4 secretion rates were assessed by analysis of medium. Experiment 2: Bioreactors were fabricated to provide a BF compartment enclosed by membranes ± adherent synoviocytes, and an external compartment of nutrient fluid (NF). A solution with HA (1 mg/mL, MW ranging from 30 to 4,000 kDa) or PRG4 (50 μg/mL) was added to the BF compartment, and HA and PRG4 loss into the NF compartment after 2, 8, and 24 h was determined. Lubricant loss kinetics were analyzed to estimate membrane permeability. Experiment 1: Cytokine-regulated HA and PRG4 secretion rates on membranes were comparable to those on TC plastic. Experiment 2: Transport of HA and PRG4 across membranes was lowest with 50 nm membranes and highest with 3 μm membranes, and transport of high MW HA was decreased by adherent synoviocytes (for 50 and 90 nm membranes). The permeability to HA mixtures for 50 nm membranes was ~20 × 10−8 cm/s (− cells) and ~5 × 10−8 cm/s (+ cells), for 90 nm membranes was ~35 × 10−8 cm/s (− cells) and ~ 19 × 10−8 cm/s (+ cells), for 170 nm membranes was ~74 × 10−8 cm/s (± cells

  13. Chemical Schemes for Maintaining Different Compositions Across a Semi-permeable Membrane with Application to Proto-cells

    NASA Astrophysics Data System (ADS)

    Bigan, Erwan; Steyaert, Jean-Marc; Douady, Stéphane

    2015-12-01

    Osmotic pressure arising from a higher total chemical concentration inside proto-cells is thought to have played a role in the emergence and selection of self-replicating proto-cells. We present two chemical schemes through which different equilibrium compositions can coexist on each side of a semi-permeable membrane. The first scheme relies upon the concept of moieties and associated number of degrees of freedom. The second scheme relies upon the concept of siphons and of pass reaction capable of transferring matter from outside a siphon into it. Using simple example reaction networks, we show that both schemes are compatible with stationary proto-cell growth with up-concentration, but suffer from shortcomings. To alleviate these we propose a third scheme derived from the second one by having the pass reaction catalyzed by the membrane surface instead of occurring in bulk solution. This may have proven an intermediate step before having the pass reaction occurring only when the nutrient crosses the membrane. This suggests an evolutionary path for the emergence of active transport.

  14. The casting of semi-permeable membranes in a microgravity environment

    NASA Technical Reports Server (NTRS)

    Vera, I.

    1986-01-01

    The experiment is to study polymeric membranes. Presently, semipermeable membranes are being manufactured from several different kinds of polymers all over the world and specific applications have been identified in fluid separation processes such as reverse osmosis, ultrafiltration and electrodialysis. Although, the ultrastructure of asymmetric and composite membranes have been under intensive study, still there are many questions about the factors affecting this structure and their degree of correlation. Nevertheless, there is indication that the entire morphological structure of polymeric membranes could be affected by the difference in specific gravity between the cast solution and the coagulation liquid normally used in the membranes preparation process. The casting of semipermeable membranes in space might help to identify the effect of gravity upon the structure of these membranes. It is important to recognize that the casting process involves changes of state and that in a microgravity environment, there will be a reduction on buoyancy-driven natural convection and density gradients.

  15. Organochlorine contaminants in double-crested cormorants from Green Bay, WI: I. Large-scale extraction and isolation from eggs using semi-permeable membrane dialysis.

    PubMed

    Meadows, J C; Tillitt, D E; Schwartz, T R; Schroeder, D J; Echols, K R; Gale, R W; Powell, D C; Bursian, S J

    1996-08-01

    A 41.3-kg sample of double-crested cormorant (Phalacrocorax auritus) egg contents was extracted, yielding over 2 L of egg lipid. The double-crested cormorant (DCC) egg extract, after clean-up and concentration, was intended for use in egg injection studies to determine the embryotoxicity of the organic contaminants found within the eggs. Large-scale dialysis was used as a preliminary treatment to separate the extracted contaminants from the co-extracted sample lipids. The lipid was dialyzed in 80x5 cm semi-permeable membrane devices (SPMDs) in 50-ml aliquants. After the removal of 87 g of cholesterol by freeze-fractionation, the remaining lipid carryover (56 g) was removed by 100 routine gel permeation chromatography (GPC) operations. A 41,293-g sample was thus extracted and purified to the extent that it could easily be placed at a volume of 5 ml, the volume calculated to be necessary for the egg injection study. Analyses were performed comparing contaminant concentrations in the final purified extract to those present in the original egg material, in the extract after dialysis and cholesterol removal, and in the excluded materials. Recoveries of organochlorine pesticides through dialysis and cholesterol ranged from 96% to 135%. Total polychlorinated biphenyls in the final extract were 96% of those measured in the original egg material. Analysis of excluded lipid and cholesterol indicated that 92% of the polychlorinated dibenzo-dioxins and -furans were separated into the final extract. PMID:8781072

  16. Application of semi-permeable membrane dialysis/ion trap mass spectrometry technique to determine polybrominated diphenyl ethers and polychlorinated biphenyls in milk fat.

    PubMed

    Roszko, Marek; Rzepkowska, Małgorzata; Szterk, Arkadiusz; Szymczyk, Krystyna; Jędrzejczak, Renata; Bryła, Marcin

    2012-10-20

    Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are hazardous food contaminants, their maximum legally allowable levels in food and environment are in the low pgg(-1) range. Therefore some highly selective and sensitive analytical methods must be used to determine them. The 96/23/EC Directive implemented by EC Decision of 12 August 2002 requires recovery rate of an analyte at a concentration below 1 ng g(-1) within the 50-120% range at relative standard deviation (RSD) as low as possible. A method to determine low level PCBs and PBDEs in milk fat based on the semi-permeable membrane dialysis/ion trap GC MS technique was developed. Validation experiments proved that the method performance was within bounds set by the currently standing UE regulations. Recovery rates calculated on the basis of labeled internal standards for majority of the studied indicator PCB congeners and PBDE congeners were close to 100% at RSD below 20%. Also, dioxin-like PCBs recovery rates were compatible with the 1883/2006 EC Regulation (80-120%, RSD below 15%). The developed method turned out to be linear within a far broader concentration range than the studied 0.0025-10 pg μL(-1) range entirely sufficient for analyses of PCB and PBDE in milk fat. Within that range coefficient of linear correlation (R(2)) of calibration curves exceeded 0.98. PMID:23021802

  17. Evaporative Cooling Membrane Device

    NASA Technical Reports Server (NTRS)

    Lomax, Curtis (Inventor); Moskito, John (Inventor)

    1999-01-01

    An evaporative cooling membrane device is disclosed having a flat or pleated plate housing with an enclosed bottom and an exposed top that is covered with at least one sheet of hydrophobic porous material having a thin thickness so as to serve as a membrane. The hydrophobic porous material has pores with predetermined dimensions so as to resist any fluid in its liquid state from passing therethrough but to allow passage of the fluid in its vapor state, thereby, causing the evaporation of the fluid and the cooling of the remaining fluid. The fluid has a predetermined flow rate. The evaporative cooling membrane device has a channel which is sized in cooperation with the predetermined flow rate of the fluid so as to produce laminar flow therein. The evaporative cooling membrane device provides for the convenient control of the evaporation rates of the circulating fluid by adjusting the flow rates of the laminar flowing fluid.

  18. Nitrification and Denitrification Communities Associated with a Semi-Permeable Swine Waste Lagoon Biocover

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ammonia emission from swine waste lagoons presents a serious environmental challenge to pork producers. Semi-permeable swine waste lagoon biocovers have been developed to serve as a physical barrier and as an attachment site for biofilm development, but microbial analysis of the biocover technology...

  19. A framework for understanding semi-permeable barrier effects on migratory ungulates

    USGS Publications Warehouse

    Sawyer, Hall; Kauffman, Matthew J.; Middleton, Arthur D.; Morrison, Thomas A.; Nielson, Ryan M.; Wyckoff, Teal B.

    2013-01-01

    1. Impermeable barriers to migration can greatly constrain the set of possible routes and ranges used by migrating animals. For ungulates, however, many forms of development are semi-permeable, and making informed management decisions about their potential impacts to the persistence of migration routes is difficult because our knowledge of how semi-permeable barriers affect migratory behaviour and function is limited. 2. Here, we propose a general framework to advance the understanding of barrier effects on ungulate migration by emphasizing the need to (i) quantify potential barriers in terms that allow behavioural thresholds to be considered, (ii) identify and measure behavioural responses to semi-permeable barriers and (iii) consider the functional attributes of the migratory landscape (e.g. stopovers) and how the benefits of migration might be reduced by behavioural changes. 3. We used global position system (GPS) data collected from two subpopulations of mule deer Odocoileus hemionus to evaluate how different levels of gas development influenced migratory behaviour, including movement rates and stopover use at the individual level, and intensity of use and width of migration route at the population level. We then characterized the functional landscape of migration routes as either stopover habitat or movement corridors and examined how the observed behavioural changes affected the functionality of the migration route in terms of stopover use. 4. We found migratory behaviour to vary with development intensity. Our results suggest that mule deer can migrate through moderate levels of development without any noticeable effects on migratory behaviour. However, in areas with more intensive development, animals often detoured from established routes, increased their rate of movement and reduced stopover use, while the overall use and width of migration routes decreased. 5. Synthesis and applications. In contrast to impermeable barriers that impede animal movement

  20. Design of a new membrane stretching device

    NASA Astrophysics Data System (ADS)

    Shao, Yiran

    Cell stretching device has been applied into the lab use for many years to help researchers study about the behavior of cells during the stretching process. Because the cell responses to the different mechanical stimuli, especially in the case of disease, the cell stretching device is a necessary tool to study the cell behavior in a controlled environment. However existing devices have limitations, such as too big to fit the culture chamber, unable to be observed during the stretching process and too expensive to fabricate. In this thesis, a new cell stretcher is designed to resolve these limitations. Many typical cell stretching devices only work under simple conditions. For instance they can only apply the strain on the cell in uniaxial or equibiaxial directions. On the other hand the environment of cells' survival is varying. Many new cell stretchers have been developed, which have the same property that cells can be stretched via the radical deformation of the elastomeric membrane. The aim of this new design is to create a cell stretching device that fits in general lab conditions. This device is designed to fit on a microscope to observe, as well as in the incubator. In addition, two small step motors are used to control the strain, adjust the frequency, and maintain the stability precisely. Problems such as the culture media leakage and the membrane breakage are solved by the usage of multiple materials for both the cell stretcher and the membrane. Based on the experimental results, this device can satisfy the requirements of target users with a reduced manufacturing cost. In the future, an auto-focus tracking function will be developed to allow real time observation of the cells' behavior.

  1. Semi-permeable coatings fabricated from comb-polymers efficiently protect proteins in vivo.

    PubMed

    Liu, Mi; Johansen, Pål; Zabel, Franziska; Leroux, Jean-Christophe; Gauthier, Marc A

    2014-01-01

    In comparison to neutral linear polymers, functional and architecturally complex (that is, non-linear) polymers offer distinct opportunities for enhancing the properties and performance of therapeutic proteins. However, understanding how to harness these parameters is challenging, and studies that capitalize on them in vivo are scarce. Here we present an in vivo demonstration that modification of a protein with a polymer of appropriate architecture can impart low immunogenicity, with a commensurably low loss of therapeutic activity. These combined properties are inaccessible by conventional strategies using linear polymers. For the model protein L-asparaginase, a comb-polymer bio-conjugate significantly outperformed the linear polymer control in terms of lower immune response and more sustained bioactivity. The semi-permeability characteristics of the coatings are consistent with the phase diagram of the polymer, which will facilitate the application of this strategy to other proteins and with other therapeutic models. PMID:25407758

  2. Tensioning device for a stretched membrane collector

    DOEpatents

    Murphy, L.M.

    1984-01-01

    Disclosed is a solar concentrating collector comprising an elestic membrane member for concentrating sunlight, a frame for holding the membrane member in plane and in tension, and a tensioning means for varying the tension of the membrane member. The tensioning means is disposed at the frame and is adapted to releasably attach the membrane member thereto. The tensioning means is also adapted to uniformly and symmetrically subject the membrane member to stretching forces such that membrane stresses produced thereby are distributed uniformly over a thickness of the membrane member and reciprocal twisting moments are substantially prevented from acting about said frame.

  3. Tensioning device for a stretched membrane collector

    DOEpatents

    Murphy, Lawrence M.

    1984-01-01

    Disclosed is a solar concentrating collector comprising an elastic membrane member for concentrating sunlight, a frame for holding the membrane member in plane and in tension, and a tensioning means for varying the tension of the membrane member. The tensioning means is disposed at the frame and is adapted to releasably attach the membrane member thereto. The tensioning means is also adapted to uniformly and symmetrically subject the membrane member to stretching forces such that membrane stresses produced thereby are distributed uniformly over a thickness of the membrane member and reciprocal twisting moments are substantially prevented from acting about said frame.

  4. Semipermeable membrane devices link site-specific contaminants to effects: Part 1 - Induction of CYP1A in rainbow trout from contaminants in Prince William Sound, Alaska.

    PubMed

    Springman, Kathrine R; Short, Jeffrey W; Lindeberg, Mandy R; Maselko, Jacek M; Khan, Colin; Hodson, Peter V; Rice, Stanley D

    2008-12-01

    Extracts from semi-permeable membrane devices (SPMDs) deployed on beaches in Prince William Sound (PWS), Alaska, were used to evaluate if complex contaminant mixtures from different sources can be distinguished by the resulting cytochrome P450 1A (CYP1A) activity in exposed test animals. Deployment sites included canneries, salmon hatcheries, and beaches where lingering oil remains from discharges during the 1964 earthquake or the 1989 Exxon Valdez oil spill. Other sites were selected at random to evaluate region-wide contaminant inputs or were located in salmon streams to evaluate contaminants carried and released by migrating salmon carcasses following reproduction. Following standard deployments of approximately 28 d, an aliquot of the accumulated contaminants was intraperitoneally injected without cleanup into juvenile rainbow trout (Oncorhynchus mykiss). After 2 d and 7 d, the activity of CYP1A was measured by the ethoxyresorufin-o-deethylase (EROD) assay. Exposure to extracts from the oiled sites and one hatchery site with numerous creosote pilings elicited strong EROD responses, whereas fish exposed to salmon stream extracts elicited weak but significant responses during late summer compared to late spring. Responses from the other sites were not significant, indicating contaminants from these sources are unlikely to cause CYP1A induction in resident biota. Rather than simply assessing extant contaminants, this method evaluates the potency of the different sites for bringing about aryl hydrocarbon receptor responses in resident biota. PMID:18845333

  5. A SURVEY OF INDOOR AIR CONTAMINATES USING SEMIPERMEABLE MEMBRANE DEVICES

    EPA Science Inventory

    Semipermeable membrane devices (SPMDs) were deployed in indoor areas in approximately 50 residences along the border between Arizona and Mexico to measure airborne contaminants. The results of the primary analyses and gas chromatographic/mass spectrometric confirmation for org...

  6. Use of Semipermeable Membrane Devices (SPMDs) in Petroleum Polluted Waters

    USGS Publications Warehouse

    Alvarez, David A.

    2010-01-01

    Passive samplers, in particular semipermeable membrane devices (SPMDs), can be used in monitoring petroleum spills. This document is intended to provide a brief discussion of issues surrounding the use and capabilities of the SPMD.

  7. Development of active-transport membrane devices

    SciTech Connect

    Laciak, D.V.

    1994-07-01

    This report introduces the concept of Air Products` AT membranes for the separation of NH{sub 3} and CO{sub 2} from process gas streams and presents results from the first year fabrication concept development studies.

  8. Gas Transfer in Cellularized Collagen-Membrane Gas Exchange Devices

    PubMed Central

    Lo, Justin H.; Bassett, Erik K.; Penson, Elliot J. N.; Hoganson, David M.

    2015-01-01

    Chronic lower respiratory disease is highly prevalent in the United States, and there remains a need for alternatives to lung transplant for patients who progress to end-stage lung disease. Portable or implantable gas oxygenators based on microfluidic technologies can address this need, provided they operate both efficiently and biocompatibly. Incorporating biomimetic materials into such devices can help replicate native gas exchange function and additionally support cellular components. In this work, we have developed microfluidic devices that enable blood gas exchange across ultra-thin collagen membranes (as thin as 2 μm). Endothelial, stromal, and parenchymal cells readily adhere to these membranes, and long-term culture with cellular components results in remodeling, reflected by reduced membrane thickness. Functionally, acellular collagen-membrane lung devices can mediate effective gas exchange up to ∼288 mL/min/m2 of oxygen and ∼685 mL/min/m2 of carbon dioxide, approaching the gas exchange efficiency noted in the native lung. Testing several configurations of lung devices to explore various physical parameters of the device design, we concluded that thinner membranes and longer gas exchange distances result in improved hemoglobin saturation and increases in pO2. However, in the design space tested, these effects are relatively small compared to the improvement in overall oxygen and carbon dioxide transfer by increasing the blood flow rate. Finally, devices cultured with endothelial and parenchymal cells achieved similar gas exchange rates compared with acellular devices. Biomimetic blood oxygenator design opens the possibility of creating portable or implantable microfluidic devices that achieve efficient gas transfer while also maintaining physiologic conditions. PMID:26020102

  9. A new integrated membrane filtration and chromatographic device.

    PubMed

    Xu, Yanke; Sirkar, Kamalesh K; Dai, Xiao-Ping; Luo, Robert G

    2005-01-01

    To improve protein separation, a novel integrated device combining membrane filtration and chromatography has been developed. The device basically consists of a hollow fiber filtration module whose shell side is filled with chromatographic resin beads. However, there is an essentially impermeable coated zone near the hollow fiber module outlet. The integrated device enjoys the advantages of both membrane filtration and chromatography; it also allows one to load the chromatographic media directly from the fermentation broth or lysate and separate the adsorbed proteins through the subsequent elution step in a cyclic process. Interfacial polymerization was carried out to coat the bottom section of the hollow fiber membrane; the rest of the hollow fiber membrane remained unaffected. Myoglobin (Mb) and alpha-lactalbumin (alpha-LA) were primarily used as model proteins in a binary mixture; binary mixtures of Mb and bovine serum albumin (BSA) were also investigated. Separation behaviors of binary protein mixtures were studied in devices having either an ultrafiltration (UF) or a microfiltration (MF) membrane. Experimental results show that the breakthrough time and the protein loading capacities were dramatically improved after introducing the impermeable coating in both UF and MF modules. For a synthetic yeast fermentation broth feed, four loading-washing-elution-reequilibration-based cyclic runs for separation of Mb and alpha-LA were performed in the device using a MF membrane with a coated zone without cleaning in between. The Mb and alpha-LA elution profiles for the four consecutive runs were almost superimposable. Due to lower transmembrane flux in this device plus the periodical washing-elution during the chromatographic separation, fouling was not a problem, unlike in conventional microfiltration. PMID:15801803

  10. Anodic Aluminum Oxide (AAO) Membranes for Cellular Devices

    NASA Astrophysics Data System (ADS)

    Ventura, Anthony P.

    Anodic Aluminum Oxide (AAO) membranes can be fabricated with a highly tunable pore structure making them a suitable candidate for cellular hybrid devices with single-molecule selectivity. The objective of this study was to characterize the cellular response of AAO membranes with varying pore sizes to serve as a proof-of-concept for an artificial material/cell synapse system. AAO membranes with pore diameters ranging from 34-117 nm were achieved via anodization at a temperature of -1°C in a 2.7% oxalic acid electrolyte. An operating window was established for this setup to create membranes with through-pore and disordered pore morphologies. C17.2 neural stem cells were seeded onto the membranes and differentiated via serum withdrawal. The data suggests a highly tunable correlation between AAO pore diameter and differentiated cell populations. Analysis of membranes before and after cell culture indicated no breakdown of the through-pore structure. Immunocytochemistry (ICC) showed that AAO membranes had increased neurite outgrowth when compared to tissue culture treated (TCT) glass, and neurite outgrowth varied with pore diameter. Additionally, lower neuronal percentages were found on AAO as compared to TCT glass; however, neuronal population was also found to vary with pore diameter. Scanning electron microscopy (SEM) and ICC images suggested the presence of a tissue-like layer with a mixed-phenotype population. AAO membranes appear to be an excellent candidate for cellular devices, but more work must be completed to understand the surface chemistry of the AAO membranes as it relates to cellular response.

  11. APPLICATION OF SEMIPERMEABLE MEMBRANE DEVICES TO INDOOR AIR SAMPLING

    EPA Science Inventory

    Semipermeable membrane devices (SPMDs) are a relatively new passive sampling technique for nonpolar organic compounds that have been extensively used for surface water sampling. A small body of literature indicates that SPMDs are also useful for air sampling. Because SPMDs ha...

  12. Semipermeable membrane devices used to estimate bioconcentration of polychlorinated biphenyls

    USGS Publications Warehouse

    Chambers, D.B.

    1999-01-01

    Aquatic organisms passively accumulate hydrophobic organic compounds, such as polychlorinated biphenyls, even when ambient water concentrations of the contaminant are below analytical detection limits. However, contaminant concentrations in tissue samples are subject to an inherently high level of variability due to differences in species, life stage, and gender bioconcentration potentials. Semipermeable membrane devices (SPMDs) were used to sample Aroclor 1254, a mixture of readily bioconcentrated polychlorinated biphenyls (PCBs), in a contaminated wetland near Flat Top, WV. The devices consisted of triolein, a lipid found in fish, enclosed in a polyethylene membrane. SPMDs were deployed in the water column and in direct contact with wetland sediments along a previously identified concentration gradient of PCBs. The devices were retrieved after a 25-day exposure period. Analytes were recovered by dialyzing the devices in nanograde hexane. Hexane dialysates were condensed and analyzed by gas chromatography. All deployed devices sequestered quantifiable amounts of Aroclor 1254. Water-column SPMDs accumulated PCBs far in excess of ambient water concentrations. The devices contacting sediments accumulated PCBs at all sites, though accumulated concentrations did not exceed concentrations in sediment. Patterns of PCB concentration in the devices corresponded to the identified gradient at the site. Results from the water-column SPMDs were used to estimate the concentration of the dissolved, bioavailable fraction of PCBs present in the water column. These concentrations ranged from 0.01 to 0.09 ??g/L of bioavailable Aroclor 1254.

  13. Mathematical modeling of a flat-membrane-controlled release device

    SciTech Connect

    Ramraj, R.; Farrell, S.; Loney, N.W.

    1999-08-01

    The closed form solution to a mathematical model of a flat membrane device successfully predicts the release profile of benzoic acid. Physically, the device consists of a given concentration of benzoic acid in octanol (reservoir) bounded by a microporous flat film (Cellgard 2400) with water-filled pores. The prediction shows excellent agreement with the experimentally derived release profile (maximum difference < 10%). Predicted results are obtained from the use of the steady state plus the first term of the transient solution (infinite series) and with the use of the first nonzero eigenvalue.

  14. A venturi device reduces membrane fouling in a submerged membrane bioreactor.

    PubMed

    Kayaalp, Necati; Ozturkmen, Gokmen

    2016-01-01

    In this study, for the first time, a venturi device was integrated into a submerged membrane bioreactor (MBR) to improve membrane surface cleaning and bioreactor oxygenation. The performances of a blower and the venturi device were compared in terms of membrane fouling and bioreactor oxygenation. Upon comparing membrane fouling, the performances were similar for a low operation flux (18 L/m(2).h); however, at a medium flux (32 L/m(2).h), the venturi system operated 3.4 times longer than the blower system, and the final transmembrane pressure was one-third that of the blower system. At the highest flux studied (50 L/m(2).h), the venturi system operated 5.4 times longer than the blower system. The most notable advantage of using a venturi device was that the dissolved oxygen (DO) concentration of the MBR was in the range of 7 to 8 mg/L at a 3 L/min aeration rate, while the DO concentration of the MBR was inadequate (a maximum of 0.29 mg/L) in the blower system. A clean water oxygenation test at a 3 L/min aeration rate indicated that the standard oxygen transfer rate for the venturi system was 9.5 times higher than that of the blower system. PMID:27386992

  15. Separation of bioactive peptides by membrane processes: technologies and devices.

    PubMed

    Bazinet, Laurent; Firdaous, Loubna

    2013-04-01

    Although many patents reported bioactive peptides with numerous demonstrated bioactivities and potential applications, there exist some limitations to the production of large quantities to satisfy the growing market demands. Indeed, considering that most functional peptides are present in complex matrices containing a large number of hydrolyzed protein fractions, their separation and purification are required. Some advances have been made in the use of conventional pressure-driven processes for the continuous production and separation of peptides, however, most of these patented technologies are not scalable and demonstrate a low selectivity when separating similar sized biomolecules. To improve the separation efficiency, the use of an external electric field during pressure-driven filtration was proposed and patented. However, whatever the claims, the pressure gradient brings about the accumulation of peptides at the nearby membrane surface and affects the membrane transport selectivity. To overcome these drawbacks, a recent patent proposed the simultaneous fractionation of acidic and basic peptides, using a conventional electrodialysis cell, in which some ion exchange membranes are replaced by ultrafiltration ones. The perspectives in the field of peptide separation will be the development of new membrane materials and new equipments such as microfluidic devices to improve selectivity and yield of production. PMID:23003009

  16. Nanoscale pressure sensors realized from suspended graphene membrane devices

    SciTech Connect

    Aguilera-Servin, Juan; Miao, Tengfei; Bockrath, Marc

    2015-02-23

    We study the transport properties of graphene layers placed over ∼200 nm triangular holes via attached electrodes under applied pressure. We find that the injected current division between counter electrodes depends on pressure and can be used to realize a nanoscale pressure sensor. Estimating various potential contributions to the resistivity change of the deflected graphene membrane including piezoresistivity, changing gate capacitance, and the valley Hall effect due to the pressure-induced synthetic magnetic field, we find that the valley Hall effect yields the largest expected contribution to the longitudinal resistivity modulation for accessible device parameters. Such devices in the ballistic transport regime may enable the realization of tunable valley polarized electron sources.

  17. Semi-Permeable Paleochannels as Conduits for Submarine Groundwater Discharge to the Coast in Barataria Bay, Louisiana

    NASA Astrophysics Data System (ADS)

    Breaux, A.; Kolker, A.; Telfeyan, K.; Kim, J.; Johannesson, K. H.; Cable, J. E.

    2014-12-01

    Many studies have focused on hydrological and geochemical fluxes to the ocean from land to the ocean via submarine groundwater discharge (SGD), however few have assessed these contributions of SGD in deltaic settings. The Mississippi River delta is the largest delta in North America, and the magnitude of groundwater that discharges from the river into its delta is relatively unknown. Hydrological budgets indicate that there is a large magnitude of surface water lost in the Mississippi's delta as the river flows into the Gulf of Mexico. Recent evidence in our study indicates that paleochannels, or semi-permeable buried sandy bodies that were former distributaries of the river, allow for water to discharge out of the Mississippi's main channel and into its delta driven by a difference in hydraulic head between the river and the lower lying coastal embayments. Our study uses geophysical data, including sonar and resistivity methods, to detect the location of these paleochannels in Barataria Bay, a coastal bay located in the Mississippi Delta. High resolution CHIRP sonar data shows that these paleochannel features are ubiquitous in the Mississippi Delta, whereas resistivity data indicates that lower salinity water is found during high river flow in bays proximate to the river. Sediment core analysis is also used to characterize the area of study, as well as further understand the regional geology of the Mississippi Delta and estimate values of permeability and hydraulic conductivity of sediments taken from two locations in Barataria Bay. The geophysical and sediment core data will likewise be used to contextualize geochemical data collected in the field, which includes an assessment of major cations and anions, as well as in situ Rn-222 activities, a method that has been proven to be useful as a tracer of groundwater movement. The results may be useful in understanding the potential global magnitude of hydrological and geochemical fluxes of other large rivers with

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

    PubMed

    2016-01-21

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

  19. Pilot Scale Water Gas Shift - Membrane Device for Hydrogen from Coal

    SciTech Connect

    Barton, Tom

    2013-06-30

    The objectives of the project were to build pilot scale hydrogen separation systems for use in a gasification product stream. This device would demonstrate fabrication and manufacturing techniques for producing commercially ready facilities. The design was a 2 lb/day hydrogen device which included composite hydrogen separation membranes, a water gas shift monolith catalyst, and stainless steel structural components. Synkera Technologies was to prepare hydrogen separation membranes with metallic rims, and to adjust the alloy composition in their membranes to a palladium-gold composition which is sulfur resistant. Chart was to confirm their brazing technology for bonding the metallic rims of the composite membranes to their structural components and design and build the 2 lbs/day device incorporating membranes and catalysts. WRI prepared the catalysts and completed the testing of the membranes and devices on coal derived syngas. The reactor incorporated eighteen 2'' by 7'' composite palladium alloy membranes. These membranes were assembled with three stacks of three paired membranes. Initial vacuum testing and visual inspection indicated that some membranes were cracked, either in transportation or in testing. During replacement of the failed membranes, while pulling a vacuum on the back side of the membranes, folds were formed in the flexible composite membranes. In some instances these folds led to cracks, primarily at the interface between the alumina and the aluminum rim. The design of the 2 lb/day device was compromised by the lack of any membrane isolation. A leak in any membrane failed the entire device. A large number of tests were undertaken to bring the full 2 lb per day hydrogen capacity on line, but no single test lasted more than 48 hours. Subsequent tests to replace the mechanical seals with brazing have been promising, but the technology remains promising but not proven.

  20. 78 FR 1158 - Anesthesiology Devices; Reclassification of Membrane Lung for Long-Term Pulmonary Support...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-08

    ..., 1979 (44 FR 63387), FDA published a proposed rule for classification of membrane lungs for long-term... rule and on July 16, 1982 (47 FR 31130), a final rule was published for membrane lungs for long- term... requirement for premarket approval for membrane lungs for long-term pulmonary support devices (52 FR 17732...

  1. Device and method for the measurement of gas permeability through membranes

    DOEpatents

    Agarwal, Pradeep K.; Ackerman, John; Borgialli, Ron; Hamann, Jerry; Muknahalliptna, Suresh

    2006-08-08

    A device for the measuring membrane permeability in electrical/electrochemical/photo-electrochemical fields is provided. The device is a permeation cell and a tube mounted within the cell. An electrode is mounted at one end of the tube. A membrane is mounted within the cell wherein a corona is discharged from the electrode in a general direction toward the membrane thereby generating heated hydrogen atoms adjacent the membrane. A method for measuring the effects of temperature and pressure on membrane permeability and selectivity is also provided.

  2. Purification of triolein for use in semipermeable membrane devices (SPMDs)

    USGS Publications Warehouse

    Lebo, J.A.; Almeida, F.V.; Cranor, W.L.; Petty, J.D.; Huckins, J.N.; Rastall, A.; Alvarez, D.A.; Mogensen, B.B.; Johnson, B.T.

    2004-01-01

    Analyses of triolein-containing semipermeable membrane devices (SPMDs) have sometimes been impeded by interferences caused by impurities endemic to triolein that codialyze with the analytes. Oleic acid and methyl oleate have been the most troublesome of these impurities because of their relatively high concentrations in triolein and because significant residues of both can persist even after size exclusion chromatographic (SEC) fractionation. These residues have also been blamed for false-positive signals during bioindicator testing of SPMD dialysates. To prevent these problems, a simple, cost-effective procedure was developed for purifying triolein destined for use in SPMDs: the bulk triolein is repeatedly (6x) partitioned against methanol. Tests of the procedure show that 14C-oleic acid is completely removed from the triolein. After SEC fractionation, dialysates of standard-size SPMDs made with the purified triolein contain less than 5 ??g of methyl oleate as compared to sometimes more than 500 ??g for dialysates (also after SEC) of SPMDs made with unpurified triolein. Gas chromatographic analyses with flame ionization and electron capture detection show that the purification treatment also greatly reduces the number and size of peaks caused by unidentified contaminants in the triolein. Microtox basic assay of dialysates of SPMDs shows that those made with the purified triolein have lower acute toxicities than dialysates of SPMDs made with unpurified triolein. Yeast estrogen screen (YES) testing of SPMDs fabricated with unpurified and purified triolein demonstrates that the purification process removes all background estrogenic activity. Published by Elsevier Ltd.

  3. Advanced membrane devices. Interim report for October 1996--September 1997

    SciTech Connect

    Laciak, D.V.; Langsam, M.; Lewnard, J.J.; Reichart, G.C.

    1997-12-31

    Under this Cooperative Agreement, Air Products and Chemicals, Inc. has continued to investigate and develop improved membrane technology for removal of carbon dioxide from natural gas. The task schedule for this reporting period included a detailed assessment of the market opportunity (Chapter 2), continued development and evaluation of membranes and membrane polymers (Chapter 3) and a detailed economic analysis comparing the potential of Air Products membranes to that of established acid gas removal processes (Chapter 4).

  4. A MEMS Device Capable of Measuring Near-Field Thermal Radiation between Membranes

    PubMed Central

    Feng, Chong; Tang, Zhenan; Yu, Jun; Sun, Changyu

    2013-01-01

    For sensors constructed by freestanding membranes, when the gap between a freestanding membrane and the substrate or between membranes is at micron scale, the effects of near-field radiative heat transfer on the sensors' thermal performance should be considered during sensor design. The radiative heat flux is transferred from a membrane to a plane or from a membrane to a membrane. In the current study of the near-field thermal radiation, the scanning probe technology has difficulty in making a membrane separated at micron scale parallel to a plane or another membrane. A novel MEMS (micro electromechanical system) device was developed by sacrificial layer technique in this work to realize a double parallel freestanding membrane structure. Each freestanding membrane has a platinum thin-film resistor and the distance between the two membranes is 1 μm. After evaluating the electrical and thermal characteristics of the lower freestanding membrane,experimental measurements of near-field radiative heat transfer between the lower membrane and the upper membrane were carried out by setting the lower membrane as a heat emitter and the upper membrane as a heat receiver. The near-field radiative heat transfer between the two membranes was validated by finding a larger-than-blackbody radiative heat transfer based on the experimental data. PMID:23385413

  5. Neural Membrane Signaling Platforms

    PubMed Central

    Wallace, Ron

    2010-01-01

    Throughout much of the history of biology, the cell membrane was functionally defined as a semi-permeable barrier separating aqueous compartments, and an anchoring site for proteins. Little attention was devoted to its possible regulatory role in intracellular molecular processes and neuron electrical signaling. This article reviews the history of membrane studies and the current state of the art. Emphasis is placed on natural and artificial membrane studies of electric field effects on molecular organization, especially as these may relate to impulse propagation in neurons. Implications of these studies for new designs in artificial intelligence are briefly examined. PMID:20640161

  6. Membrane processes and devices for separation of bioactive peptides.

    PubMed

    Bazinet, Laurent; Firdaous, Loubna

    2009-01-01

    In recent years, functional foods and nutraceuticals has attracted much attention, particularly for their impact on human health and prevention of certain diseases. Consequently, the production and properties of bioactive peptides has received an increasing scientific interest over the past few years. Considering that most functional peptides are present in complex matrices containing a large number of hydrolyzed protein fractions, their separation and purification are required. Conventional pressure-driven processes can be used for amino acids and peptides separation but are limited by their fouling problems and their low selectivity when separating similar sized biomolecules. To improve the separation efficiency, an external electric field was applied during pressure-driven filtration. However, the pressure gradient brings about the accumulation of peptides at the nearby membrane surface and affects the membrane transport selectivity. Processes combining an electrical field as a driving force to porous membranes have been developed for the separation of biopeptides to obtain better purified products. Compounds of higher molecular weights than the membrane cut-off can be separated. The first trials were carried-out to perform the separation of amino acids and peptides with a filtration module specially designed and using one ultrafiltration membrane. More recently, electrodialysis with ultrafiltration membranes has been developed to fractionate simultaneously acidic and basic peptides, using a conventional electrodialysis cell, in which some ion exchange membranes are replaced by ultrafiltration ones. The perspectives in this field will be the understanding of the interactions of peptides and membrane as well as the development of new membrane materials limitating or increasing these interactions to improve the selectivity and the yield of production of specific peptides. This review article also discusses recent patents related to bioactive peptides. PMID

  7. Hollow Fiber Membrane Dehumidification Device for Air Conditioning System.

    PubMed

    Zhao, Baiwang; Peng, Na; Liang, Canzeng; Yong, Wai Fen; Chung, Tai-Shung

    2015-01-01

    In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18-22 g/m³ to a range of 13.5-18.3 g/m³. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process. PMID:26580660

  8. Hollow Fiber Membrane Dehumidification Device for Air Conditioning System

    PubMed Central

    Zhao, Baiwang; Peng, Na; Liang, Canzeng; Yong, Wai Fen; Chung, Tai-Shung

    2015-01-01

    In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18–22 g/m3 to a range of 13.5–18.3 g/m3. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process. PMID:26580660

  9. SCREENING FOR TOXIC INDUSTRIAL CHEMICALS USING SEMIPERMEABLE MEMBRANE DEVICES WITH RAPID TOXICITY ASSAYS

    EPA Science Inventory

    A time-integrated sampling device interfaced with two toxicity-based assays is reported for monitoring volatile toxic industrial chemicals (TICs). Semipermeable membrane devices (SPMDs) using dimethylsulfoxide (DMSO) as the fill solvent accumulated each of 17 TICs from the vapor...

  10. Berlin Heart EXCOR Ventricular Assist Device: Multilayer Membrane Rupture in a Pediatric Patient.

    PubMed

    Di Molfetta, Arianna; Filippelli, Sergio; Ferrari, Gianfranco; Secinaro, Aurelio; Zielinski, Krystzof; Amodeo, Antonio

    2016-08-01

    A 2-year-old child was implanted with an Berlin Heart EXCOR Ventricular Assist Device (Berlin Heart, Berlin, Germany) as a bridge to heart transplantation for idiopathic dilated cardiomyopathy. At postoperative day 296, a significant reduction of membrane movement was observed. The device was explanted and tested on a hydronumerical circulation simulator. Findings suggested that the integrity of the multilayered membrane had been compromised. This was confirmed by a computed tomography scan of the device. The computed tomography evidenced a detachment of the 3-layered membrane, with a thinner, convex layer on the side of the air chamber and an opposite convexity of the remaining membranes. These showed an additional air space within the layers. PMID:27449447

  11. Hydrogel-swelling driven delivery device for corrosion resistance of metal in water.

    PubMed

    Gu, Yu; Yang, Li-Ming; Chen, Jie; Wang, Ling-Ling; Chen, Bin

    2015-01-01

    Corrosion on steel and copper pipes in industry can trigger pollution and weakness due to undesired chemical and biochemical reactions. Too much or too little inhibitor can decrease its efficiency, even causing waste and pollution. In this contribution, an innovative delivery device driven by hydrogel swelling, mainly consisting of a semi-permeable membrane, a hydrogel-swelling force drive and a release orifice, was developed to control the release of inhibitor in a water system at a constant rate, leading the amount of inhibitor to maintain a proper concentration. The effects of hydrogel mass and orifice dimension on release property were studied for controlling release rate. Moreover, a weight loss experiment on carbon steels was carried out to show the incredible anti-corrosion function of the system. PMID:26676016

  12. Sol-Gel Based Polybenzimidazole Membranes for Hydrogen Pumping Devices

    SciTech Connect

    Benicewicz, Brian

    2014-02-26

    Electrochemical hydrogen pumping using a high temperature (>100°C) PBI membrane was demonstrated under non-humidified and humidified conditions at ambient pressures. Relatively low voltages were required to operate the pump over a wide range of hydrogen flow rates. The advantages of the high temperature capability were shown by operating the pump on reformate feed gas mixtures containing various amounts of CO and CO{sub 2}. Gas purity measurements on the cathode gas product were conducted and significant reductions in gas impurities were detected. The applicability of the PBI membrane for electrochemical hydrogen pumping and its durability under typical operating conditions was established with tests that lasted for nearly 4000 hours.

  13. Silicon Nitride Membranes for Filtration and Separation

    SciTech Connect

    Galambos, Paul; Zavadil, Kevin; Shul, Randy; Willison, Christi Gober; Miller, Sam

    1999-07-19

    Semi-Permeable silicon nitride membranes have been developed using a Bosch etch process followed by a reactive ion etch (NE) process. These membranes were observed to allow air but not water to pass through them into surface micromachined, silicon nitride microfluidic channels. Membranes with this property have potential use in microfluidic systems as gas bubble traps and vents, filters to remove particles and gas partitioning membranes. Membrane permeation was measured as 1.6 x 10{sup {minus}8} mol/m{sup 2}Pa s of helium for inline membranes at the entrance and exit of the silicon nitride microfluidic channels.

  14. Polymeric barrier membranes for device packaging, diffusive control and biocompatibility

    NASA Astrophysics Data System (ADS)

    Wasikiewicz, J. M.; Roohpour, N.; Paul, D.; Grahn, M.; Ateh, D.; Rehman, I.; Vadgama, P.

    2008-11-01

    Current state-of-the-art implantable micron feature electronic devices are capable of monitoring and stimulating functions in vivo. Within an EU Framework VI project a further step was taken in developing key microsystem technologies and communication methods that could bring intelligence directly to the human interface, in the form of reactive medical implants and ambulatory measurement systems. Information from these devices is planned to be transmitted out into the wider environment for remote processing. However, the packaging of such state-of-the-art devices to enhance tissue biocompatibility, and to protect conducting elements from in vivo corrosion during extended use, along with protecting the body from toxins leaching from implant components, remains a concern. Candidate polymeric barriers as hydration resistant and solute impermeable interfaces to mitigate such major problems of chronic implantation were investigated. Materials studied included silicone rubber, PVC, polyurethane, and diamond-like carbon (DLC). Polymer permeability to water solutes was marginally improved through incorporation of lipid into these structures. Surface biocompatibility was assessed on the basis of protein film deposition in vitro and by cell viability studies in tissue culture. Short-term toxicity was not observed for any of the tested materials, though there were substantial differences in hydration. Additionally, polypyrrole over active electrodes shows feasibility for controlled tissue interfacing whilst retaining electrical conductivity.

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

    SciTech Connect

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

    2013-10-14

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

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

    SciTech Connect

    Susan Agro, Anthony DeCarmine, Shari Williams

    2005-12-30

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

  17. Hollow-Fiber Membrane Chamber as a Device for In Situ Environmental Cultivation▿

    PubMed Central

    Aoi, Yoshiteru; Kinoshita, Tomoyuki; Hata, Toru; Ohta, Hiroaki; Obokata, Haruko; Tsuneda, Satoshi

    2009-01-01

    A hollow-fiber membrane chamber (HFMC) was developed as an in situ cultivation device for environmental microorganisms. The HFMC system consists of 48 to 96 pieces of porous hollow-fiber membrane connected with injectors. The system allows rapid exchange of chemical compounds, thereby simulating a natural environment. Comparative analysis through the cultivation of three types of environmental samples was performed using this newly designed device and a conventional agar-based petri dish. The results show that the ratios of novel phylotypes in isolates, species-level diversities, and cultivabilities in HFMC-based cultivation are higher than those in an agar-based petri dish for all three samples, suggesting that the new in situ cultivation device is effective for cultivation of various environmental microorganisms. PMID:19329655

  18. Engineered Asymmetric Heterogeneous Membrane: A Concentration-Gradient-Driven Energy Harvesting Device.

    PubMed

    Zhang, Zhen; Kong, Xiang-Yu; Xiao, Kai; Liu, Qian; Xie, Ganhua; Li, Pei; Ma, Jie; Tian, Ye; Wen, Liping; Jiang, Lei

    2015-11-25

    Engineered asymmetric membranes for intelligent molecular and ionic transport control at the nanoscale have gained significant attention and offer prospects for broad application in nanofluidics, energy conversion, and biosensors. Therefore, it is desirable to construct a high-performance heterogeneous membrane capable of coordinating highly selective and rectified ionic transport with a simple, versatile, engineered method to mimic the delicate functionality of biological channels. Here, we demonstrate an engineered asymmetric heterogeneous membrane by combining a porous block copolymer (BCP) membrane, polystyrene-b-poly(4-vinylpyridine) (PS48400-b-P4VP21300), with a track-etched asymmetric porous polyethylene terephthalate membrane. The introduction of chemical, geometrical, and electrostatic heterostructures provides our heterogeneous membrane with excellent anion selectivity and ultrahigh ionic rectification with a ratio of ca. 1075, which is considerably higher than that of existing ionic rectifying systems. This anion-selective heterogeneous membrane was further developed into an energy conversion device to harvest the energy stored in an electrochemical concentration gradient. The concentration polarization phenomenon that commonly exists in traditional reverse electrodialysis can be eliminated with an asymmetric bipolar structure, which considerably increases the output power density. This work presents an important paradigm for the use of versatile BCPs in nanofluidic systems and opens new and promising routes to various breakthroughs in the fields of chemistry, materials science, bioscience, and nanotechnology. PMID:26535954

  19. Use of membranes for ethylene recovery in polymerization processes

    SciTech Connect

    Dembicki, D.R.; Coan, F.L.; Glassford, C.L.; Overman, D.C.

    1986-11-18

    This patent describes an improved process for manufacture of ethylene polymers wherein the improvement comprises: (a) contacting at least part of the gas mixture remaining after polymerization containing unconverted ethylene monomer with a normally solid, semi-permeable, asymmetric, water-dry, cellulose triacetate hollow fiber membrane at conditions which promote selective permeation of ethylene through the membrane; and (b) recycling the ethylene-enriched permeate as feed for the ethylene polymerization.

  20. Production of Fluconazole-Loaded Polymeric Micelles Using Membrane and Microfluidic Dispersion Devices.

    PubMed

    Lu, Yu; Chowdhury, Danial; Vladisavljević, Goran T; Koutroumanis, Konstantinos; Georgiadou, Stella

    2016-01-01

    Polymeric micelles with a controlled size in the range between 41 and 80 nm were prepared by injecting the organic phase through a microengineered nickel membrane or a tapered-end glass capillary into an aqueous phase. The organic phase was composed of 1 mg·mL(-1) of PEG-b-PCL diblock copolymers with variable molecular weights, dissolved in tetrahydrofuran (THF) or acetone. The pore size of the membrane was 20 μm and the aqueous/organic phase volumetric flow rate ratio ranged from 1.5 to 10. Block copolymers were successfully synthesized with Mn ranging from ~9700 to 16,000 g·mol(-1) and polymeric micelles were successfully produced from both devices. Micelles produced from the membrane device were smaller than those produced from the microfluidic device, due to the much smaller pore size compared with the orifice size in a co-flow device. The micelles were found to be relatively stable in terms of their size with an initial decrease in size attributed to evaporation of residual solvent rather than their structural disintegration. Fluconazole was loaded into the cores of micelles by injecting the organic phase composed of 0.5-2.5 mg·mL(-1) fluconazole and 1.5 mg·mL(-1) copolymer. The size of the drug-loaded micelles was found to be significantly larger than the size of empty micelles. PMID:27231945

  1. Production of Fluconazole-Loaded Polymeric Micelles Using Membrane and Microfluidic Dispersion Devices

    PubMed Central

    Lu, Yu; Chowdhury, Danial; Vladisavljević, Goran T.; Koutroumanis, Konstantinos; Georgiadou, Stella

    2016-01-01

    Polymeric micelles with a controlled size in the range between 41 and 80 nm were prepared by injecting the organic phase through a microengineered nickel membrane or a tapered-end glass capillary into an aqueous phase. The organic phase was composed of 1 mg·mL−1 of PEG-b-PCL diblock copolymers with variable molecular weights, dissolved in tetrahydrofuran (THF) or acetone. The pore size of the membrane was 20 μm and the aqueous/organic phase volumetric flow rate ratio ranged from 1.5 to 10. Block copolymers were successfully synthesized with Mn ranging from ~9700 to 16,000 g·mol−1 and polymeric micelles were successfully produced from both devices. Micelles produced from the membrane device were smaller than those produced from the microfluidic device, due to the much smaller pore size compared with the orifice size in a co-flow device. The micelles were found to be relatively stable in terms of their size with an initial decrease in size attributed to evaporation of residual solvent rather than their structural disintegration. Fluconazole was loaded into the cores of micelles by injecting the organic phase composed of 0.5–2.5 mg·mL−1 fluconazole and 1.5 mg·mL−1 copolymer. The size of the drug-loaded micelles was found to be significantly larger than the size of empty micelles. PMID:27231945

  2. Gelatin- and DNA-based ionic conducting membranes for electrochromic devices

    NASA Astrophysics Data System (ADS)

    Pawlicka, A.; Firmino, A.; Vieira, D.; Sentanin, F.; Grote, J. G.; Kajzar, F.

    2009-09-01

    Gelatin and DNA are abundant natural products with very good biodegradation properties and can be used to obtain acetic acid or LiClO4-based gel polymer electrolytes (GPEs) with high ionic conductivity and good stability. This article presents the results of the ionic conductivity measurements of GPEs membranes based on crosslinked and plasticized gelatin and on plasticized DNA as well as on inserted/extracted charge density of electrochemical devices (ECDs) obtained with these samples. The membranes were analyzed by impedance spectroscopy, UV-Vis spectroscopy and the ECDs by charge density measurements, respectively. At room temperature the measured ionic conductivity of the membranes is in the range of 10-4-10-5 S/cm. It obeys predominantly an Arrhenius relationship in function of temperature. The ECD with red gelatin changed the color from red to deep red and the ECD with DNA-based electrolyte changes from transparent to blue. The inserted charge density values of these ECDs were of -3.0 mC/cm2 for the device with red gelatin and -6.6 mC/cm2 for the ECD with DNA-based electrolyte. The reverse potential application promoted a charge extraction and, as consequence, bleaching of the devices. Good ionic conductivity results combined with transparency and good adhesion to the electrodes and promising preliminary results of small ECDs have shown that gelatin and DNA-based GPEs are very promising materials to be used as gel polymer electrolytes in electrochromic devices.

  3. A thin permeable-membrane device for single-molecule manipulation

    NASA Astrophysics Data System (ADS)

    Park, Chang-Young; Jacobson, David R.; Nguyen, Dan T.; Willardson, Sam; Saleh, Omar A.

    2016-01-01

    Single-molecule manipulation instruments have unparalleled abilities to interrogate the structure and elasticity of single biomolecules. Key insights are derived by measuring the system response in varying solution conditions; yet, typical solution control strategies require imposing a direct fluid flow on the measured biomolecule that perturbs the high-sensitivity measurement and/or removes interacting molecules by advection. An alternate approach is to fabricate devices that permit solution changes by diffusion of the introduced species through permeable membranes, rather than by direct solution flow through the sensing region. Prior implementations of permeable-membrane devices are relatively thick, disallowing their use in apparatus that require the simultaneous close approach of external instrumentation from two sides, as occurs in single-molecule manipulation devices like the magnetic tweezer. Here, we describe the construction and use of a thin microfluidic device appropriate for single-molecule studies. We create a flow cell of only ˜500 μm total thickness by sandwiching glass coverslips around a thin plastic gasket and then create permeable walls between laterally separated channels in situ through photo-induced cross-linking of poly(ethylene glycol) diacrylate hydrogels. We show that these membranes permit passage of ions and small molecules (thus permitting solution equilibration in the absence of direct flow), but the membranes block the passage of larger biomolecules (thus retaining precious samples). Finally, we demonstrate the suitability of the device for high-resolution magnetic-tweezer experiments by measuring the salt-dependent folding of a single RNA hairpin under force.

  4. Modelling heat and mass transfer in a membrane-based air-to-air enthalpy exchanger

    NASA Astrophysics Data System (ADS)

    Dugaria, S.; Moro, L.; Del, D., Col

    2015-11-01

    The diffusion of total energy recovery systems could lead to a significant reduction in the energy demand for building air-conditioning. With these devices, sensible heat and humidity can be recovered in winter from the exhaust airstream, while, in summer, the incoming air stream can be cooled and dehumidified by transferring the excess heat and moisture to the exhaust air stream. Membrane based enthalpy exchangers are composed by different channels separated by semi-permeable membranes. The membrane allows moisture transfer under vapour pressure difference, or water concentration difference, between the two sides and, at the same time, it is ideally impermeable to air and other contaminants present in exhaust air. Heat transfer between the airstreams occurs through the membrane due to the temperature gradient. The aim of this work is to develop a detailed model of the coupled heat and mass transfer mechanisms through the membrane between the two airstreams. After a review of the most relevant models published in the scientific literature, the governing equations are presented and some simplifying assumptions are analysed and discussed. As a result, a steady-state, two-dimensional finite difference numerical model is setup. The developed model is able to predict temperature and humidity evolution inside the channels. Sensible and latent heat transfer rate, as well as moisture transfer rate, are determined. A sensitive analysis is conducted in order to determine the more influential parameters on the thermal and vapour transfer.

  5. A novel membrane device for the removal of water vapor and water droplets from air

    NASA Technical Reports Server (NTRS)

    Ray, Rod; Newbold, David D.; Mccray, Scott B.; Friesen, Dwayne T.; Kliss, Mark

    1992-01-01

    One of the key challenges facing NASA engineers is the development of systems for separating liquids and gases in microgravity environments. In this paper, a novel membrane-based phase separator is described. This device, known as a water recovery heat exchanger (WRHEX), overcomes the inherent deficiencies of current phase-separation technology. Specifically, the WRHEX cools and removes water vapor or water droplets from feed-air streams without the use of a vacuum or centrifugal force. As is shown in this paper, only a low-power air blower and a small stream of recirculated cool water is required for WRHEX operation. This paper presents the results of tests using this novel membrane device over a wide range of operating conditions. The data show that the WRHEX produces a dry air stream containing no entrained or liquid water - even when the feed air contains water droplets or mist. An analysis of the operation of the WRHEX is presented.

  6. Fabrication and characterization of an integrated ionic device from suspended polypyrrole and alamethicin-reconstituted lipid bilayer membranes

    NASA Astrophysics Data System (ADS)

    Northcutt, Robert; Sundaresan, Vishnu-Baba

    2012-09-01

    Conducting polymers are electroactive materials that undergo conformal relaxation of the polymer backbone in the presence of an electrical field through ion exchange with solid or aqueous electrolytes. This conformal relaxation and the associated morphological changes make conducting polymers highly suitable for actuation and sensing applications. Among smart materials, bioderived active materials also use ion transport for sensing and actuation functions via selective ion transport. The transporter proteins extracted from biological cell membranes and reconstituted into a bilayer lipid membrane in bioderived active materials regulate ion transport for engineering functions. The protein transporter reconstituted in the bilayer lipid membrane is referred to as the bioderived membrane and serves as the active component in bioderived active materials. Inspired by the similarities in the physics of transduction in conducting polymers and bioderived active materials, an integrated ionic device is formed from the bioderived membrane and the conducting polymer membrane. This ionic device is fabricated into a laminated thin-film membrane and a common ion that can be processed by the bioderived and the conducting polymer membranes couple the ionic function of these two membranes. An integrated ionic device, fabricated from polypyrrole (PPy) doped with sodium dodecylbenzenesulfonate (NaDBS) and an alamethicin-reconstituted DPhPC bilayer lipid membrane, is presented in this paper. A voltage-gated sodium current regulates the electrochemical response in the PPy(DBS) layer. The integrated device is fabricated on silicon-based substrates through microfabrication, electropolymerization, and vesicle fusion, and ionic activity is characterized through electrochemical measurements.

  7. Detection of persistent organic pollutants in the Mississippi Delta using semipermeable membrane devices

    USGS Publications Warehouse

    Zimmerman, L.R.; Thurman, E.M.; Bastian, K.C.

    2000-01-01

    From semipermeable membrane devices (SPMDs) placed in five Mississippi Delta streams in 1996 and 1997, the persistent organic pollutants (POPs) aldrin, chlordane, DCPA, DDT, dieldrin, endrin, heptachlor, mirex, nonachlor, and toxaphene were detected. In addition, the insecticides chlorpyriphos, endosulfan, and hexachlorocyclohexanes were detected. Two low-solubility herbicides not detected commonly in surface water, pendimethalin and trifluralin, were also detected. Copyright (C) 2000 Elsevier Science B.V.

  8. Controlled systemic delivery of indomethacin using membrane-moderated, cream formulation-based transdermal devices.

    PubMed

    Rao, P Rama; Chalasani, Kishore B; Chauhan, Abhay S; Jain, Akhlesh K; Diwan, Prakash V; Ram, Meduri Kodanda

    2006-01-01

    The present study was carried out to design a viable and practically effective transdermal systems of indomethacin using cream-based drug reservoirs and suitable rate controlling membranes. As vehicles, a more lipophilic base (F(1)) and a cream formulation containing predominant aqueous phase (F(2)) were chosen to study the influence of vehicle nature and role of permeation enhancers that increases thermodynamic activity and to provide diffusible species of drug to skin. Rate controlling membranes of cellulose acetate (CA) and ethyl cellulose (EC) with polyvinyl pyrollidine and hydroxypropyl methyl cellulose were used to design transdermal devices. In vivo, effective plasma concentrations of indomethacin are maintained up to 24 hr whereas oral formulation showed only up to 8 hr. Although the plasma drug levels between both EC films differ insignificantly, PVP film showed a better pharmacokinetic profile. The pharmacodynamic performance of the transdermal devices exhibited good anti-inflammatory activity over 24 hr compared with orally administered indomethacin. In vivo studies indicate the superiority of CA films over the EC films. Further, enhancement may be achieved with other classic enhancers/enhancement strategies with such devices containing aqueous cream vehicle and the optimum membranes. PMID:16556573

  9. A Potential Nanofiber Membrane Device for Filling Surgical Residual Cavity to Prevent Glioma Recurrence and Improve Local Neural Tissue Reconstruction

    PubMed Central

    Huang, Daoxiang; Lin, Chao; Wen, Xuejun; Gu, Shuying; Zhao, Peng

    2016-01-01

    This study aims to develop a novel device with nanofiber membrane capable of sustained release of temozolomide (TMZ) and neuron growth factor (NGF). An improved bio-availability of TMZ and NGF in surroundings proximal to the device was expected to be attained for a prolonged period of time. The device was developed by integrating TMZ-doped polycaprolactone (PCL) nanofiber (TP) membrane and NGF-coated PCL (NGFP) membrane using sodium alginate hydrogel. TP was prepared by direct electrospinning of TMZ/PCL. NGFP membrane was developed by layer-by-layer assembling technology. The incorporation of TMZ-doped nanofiber and NGFP nanofiber in the device was confirmed by scanning electron microscopy. The number of NGF layer in NGF-coated PCL membrane could be readily measured with energy spectrum analysis. The in vitro release study showed that TP-NGFP-TP membrane could efficiently liberate TMZ to inhibit the growth of C6 glioma cells, and sufficient NGF to induce the differentiation of PC12 neuron cells over four weeks. Such TP-NGFP-TP membrane device can be employed as a tampon to fill up surgical residual cavity and afford residual glioma removal, structural support, hemostasis, and local neural tissue reconstruction in the surgical treatment of glioma. The study opens a horizon to develop multifunctional biomaterial device for maximized glioma treatment efficacy. PMID:27548322

  10. A Potential Nanofiber Membrane Device for Filling Surgical Residual Cavity to Prevent Glioma Recurrence and Improve Local Neural Tissue Reconstruction.

    PubMed

    Huang, Daoxiang; Lin, Chao; Wen, Xuejun; Gu, Shuying; Zhao, Peng

    2016-01-01

    This study aims to develop a novel device with nanofiber membrane capable of sustained release of temozolomide (TMZ) and neuron growth factor (NGF). An improved bio-availability of TMZ and NGF in surroundings proximal to the device was expected to be attained for a prolonged period of time. The device was developed by integrating TMZ-doped polycaprolactone (PCL) nanofiber (TP) membrane and NGF-coated PCL (NGFP) membrane using sodium alginate hydrogel. TP was prepared by direct electrospinning of TMZ/PCL. NGFP membrane was developed by layer-by-layer assembling technology. The incorporation of TMZ-doped nanofiber and NGFP nanofiber in the device was confirmed by scanning electron microscopy. The number of NGF layer in NGF-coated PCL membrane could be readily measured with energy spectrum analysis. The in vitro release study showed that TP-NGFP-TP membrane could efficiently liberate TMZ to inhibit the growth of C6 glioma cells, and sufficient NGF to induce the differentiation of PC12 neuron cells over four weeks. Such TP-NGFP-TP membrane device can be employed as a tampon to fill up surgical residual cavity and afford residual glioma removal, structural support, hemostasis, and local neural tissue reconstruction in the surgical treatment of glioma. The study opens a horizon to develop multifunctional biomaterial device for maximized glioma treatment efficacy. PMID:27548322

  11. Sensor-actuator coupled device for active tracheal tube using solid polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    Ihara, Tadashi; Nakamura, Taro; Mukai, Toshiharu; Asaka, Kinji

    2007-04-01

    A sensor-actuator coupled device was developed using solid polymer electrolyte membrane (SPM) as an active tracheal tube for ventilator. Active tracheal tube is a novel type of tube for ventilator that removes patient's phlegm automatically upon sensing the narrowing of trachea by phlegm. This type of active tube is extremely useful in clinical settings as currently the sole measure to remove phlegm from patient's tube is to do it manually by a nurse every few hours. As SPM works both as a sensor and an actuator, an effective compact device was developed. SPM based sensor-actuator coupled device was fabricated with modified gold plating method. Prepared SPM was fixed as an array on a plastic pipe of diameter 22 mm and was connected to a ventilator circuit and driven by a ventilator with a volume control ventilation (VCV) mode. SPM was connected both to a sensing unit and an actuation unit. Generated voltage developed by the membrane with the setting of the maximum pressure from 5 cmH IIO to 20 cmH IIO was in order of several hundred μV. SPM sensor demonstrated a biphasic response to the ventilator flow. The sensor data showed nearly linearly proportional voltage development to the intra-tracheal pressure. The sensed signal was filtered and digitized with an A/D converting unit on a PC board. A real time operating program was used to detect the sensed signal that indicates the narrowing of trachea. The program then activated a driving signal to control the actuation of the membrane. The signal was sent to a D/A converting unit. The output of the D/A unit was sent to an amplifier and the galvanostat unit which drives the membrane with constant current regardless of the change in the load. It was demonstrated that the sensor-actuator unit detects the narrowing of trachea within several hundreds milli-seconds and responds by actuating the same membrane with the driving voltage of 3-4 V and driving current of several hundred milli-ampere for each membrane. SPM array

  12. HPLC-PFD determination of priority pollutant PAHs in water, sediment, and semipermeable membrane devices

    USGS Publications Warehouse

    Williamson, K.S.; Petty, J.D.; Huckins, J.N.; Lebo, J.A.; Kaiser, E.M.

    2002-01-01

    High performance liquid chromatography coupled with programmable fluorescence detection was employed for the determination of 15 priority pollutant polycyclic aromatic hydrocarbons (PPPAHs) in water, sediment, and semipermeable membrane devices (SPMDs). Chromatographic separation using this analytical method facilitates selectivity, sensitivity (ppt levels), and can serve as a non-destructive technique for subsequent analysis by other chromatographic and spectroscopic techniques. Extraction and sample cleanup procedures were also developed for water, sediment, and SPMDs using various chromatographic and wet chemical methods. The focus of this publication is to examine the enrichment techniques and the analytical methodologies used in the isolation, characterization, and quantitation of 15 PPPAHs in different sample matrices.

  13. Considerations involved with the use of semipermeable membrane devices for monitoring environmental contaminants

    USGS Publications Warehouse

    Petty, J.D.; Orazio, C.E.; Huckins, J.N.; Gale, R.W.; Lebo, J.A.; Meadows, J.C.; Echols, K.R.; Cranor, W.L.

    2000-01-01

    Semipermeable membrane devices (SPMDs) are used with increasing frequency, and throughout the world as samplers of organic contaminants. The devices can be used to detect a variety of lipophilic chemicals in water, sediment/soil, and air. SPMDs are designed to sample nonpolar, hydrophobic chemicals. The maximum concentration factor achievable for a particular chemical is proportional to its octanol-water partition coefficient. Techniques used for cleanup of SPMD extracts for targeted analytes and for general screening by full-scan mass spectrometry do not differ greatly from techniques used for extracts of other matrices. However, SPMD extracts contain potential interferences that are specific to the membrane-lipid matrix. Procedures have been developed or modified to alleviate these potential interferences. The SPMD approach has been demonstrated to be applicable to sequestering and analyzing a wide array of environmental contaminants including organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polychlorinated dioxins and dibenzofurans, selected organophosphate pesticides and pyrethroid insecticides, and other nonpolar organic chemicals. We present herein an overview of effective procedural steps for analyzing exposed SPMDs for trace to ultra-trace levels of contaminants sequestered from environmental matrices. Copyright (C) 2000.

  14. Three-compartment model for contaminant accumulation by semipermeable membrane devices

    USGS Publications Warehouse

    Gale, R.W.

    1998-01-01

    Passive sampling of dissolved hydrophobic contaminants with lipid (triolein)-containing semipermeable membrane devices (SPMDs) has been gaining acceptance for environmental monitoring. Understanding of the accumulation process has employed a simple polymer film-control model of uptake by the polymer-enclosed lipid, while aqueous film control has been only briefly discussed. A more complete three-compartment model incorporating both aqueous film (turbulent-diffusive) and polymer film (diffusive) mass transfer is developed here and is fit to data from accumulation studies conducted in constant-concentration, flow-through dilutors. This model predicts aqueous film control of the whole device for moderate to high K(ow) compounds, rather than polymer film control. Uptake rates for phenanthrene and 2,2',5,5'- tetrachlorobiphenyl were about 4.8 and 4.2 L/day/standard SPMD, respectively. Maximum 28 day SPMD concentration factors of 30 000 are predicted for solutes with log K(ow) values of >5.5. Effects of varying aqueous and polymer film thicknesses and solute diffusivities in the polymer film are modeled, and overall accumulation by the whole device is predicted to remain under aqueous film control, although accumulation in the triolein may be subject to polymer film control. The predicted half-life and integrative response of SPMDs to pulsed concentration events is proportional to log K(SPMD).Passive sampling of dissolved hydrophobic contaminants with lipid (triolein)-containing semipermeable membrane devices (SPMDs) has been gaining acceptance for environmental monitoring. Understanding of the accumulation process has employed a simple polymer film-control model of uptake by the polymer-enclosed lipid, while aqueous film control has been only briefly discussed. A more complete three-compartment model incorporating both aqueous film (turbulent-diffusive) and polymer film (diffusive) mass transfer is developed here and is fit to data from accumulation studies conducted in

  15. Dense chitosan surgical membranes produced by a coincident compression-dehydration process

    PubMed Central

    Dooley, Thomas P.; Ellis, April L.; Belousova, Maria; Petersen, Don; DeCarlo, Arthur A.

    2012-01-01

    High density chitosan membranes were produced via a novel manufacturing process for use as implantable resorbable surgical membranes. The innovative method utilizes the following three sequential steps: (1) casting an acidic chitosan solution within a silicon mold, followed by freezing; (2) neutralizing the frozen acidic chitosan solution in alkaline solution to facilitate polymerization; and (3) applying coincident compression-dehydration under a vacuum. Resulting membranes of 0.2 – 0.5 mm thickness have densities as high as 1.6 g/cm3. Inclusion of glycerol prior to the compression-dehydration step provides additional physical and clinical handling benefits. The biomaterials exhibit tensile strength with a maximum load as high as 10.9 N at ~ 2.5 mm width and clinically-relevant resistance to suture pull-out with a maximum load as high as 2.2 N. These physical properties were superior to those of a commercial reconstituted collagen membrane. The dense chitosan membranes have excellent clinical handling characteristics, such as pliability and “memory” when wet. They are semi-permeable to small molecules, biodegradable in vitro in lysozyme solution, and the rates of degradation are inversely correlated to the degree of deacetylation. Furthermore, the dense chitosan membranes are biocompatible and resorbable in vivo as demonstrated in a rat oral wound healing model. The unique combination of physical, in vitro, in vivo, and clinical handling properties demonstrate the high utility of dense chitosan membranes produced by this new method. The materials may be useful as surgical barrier membranes, scaffolds for tissue engineering, wound dressings, and as delivery devices for active ingredients. PMID:23565872

  16. Pancreatic acellular matrix supports islet survival and function in a synthetic tubular device: in vitro and in vivo studies.

    PubMed

    De Carlo, E; Baiguera, S; Conconi, M T; Vigolo, S; Grandi, C; Lora, S; Martini, C; Maffei, P; Tamagno, G; Vettor, R; Sicolo, N; Parnigotto, P P

    2010-02-01

    Increasing pancreatic islet survival and function is a starting point for obtaining a valuable bioartificial pancreas for the treatment of type 1 diabetes. In this context, decellularized matrices, obtained after the removal of tissue cellular part, are known to support in vitro adhesion, growth, and function of several cell types. We demonstrate that a homologous acellular pancreatic matrix is a suitable scaffold for rat islet cultures maintaining their long-term viability and function. Islets adhered to the pancreatic matrix showed a constant glucose-induced insulin release during long-term in vitro incubation, while islets cultured without a matrix or on the liver matrix showed a progressive reduction. In order to obtain implantable devices, acellular matrix/islet cultures were entrapped into poly(vinyl alcohol) (PVA)/ poly(ethylene glycol) (PEG) tubes obtained by the freezing/thawing procedure. Under this condition, an in vitro constant insulin release was detected. The devices were then implanted into diabetic rats where reduced insulin requirement was noted suggesting insulin secretory activity of islets contained in the device. Indeed, immunofluorescence confirmed the presence of insulin- and glucagon-producing cells into the explanted devices. These data show that PVA/PEG semi-permeable membrane can obtain devices that restore, at least in part, insulin secretion. PMID:20043127

  17. Dialysis membrane for separation on microchips

    DOEpatents

    Singh, Anup K.; Kirby, Brian J.; Shepodd, Timothy J.

    2010-07-13

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and forms a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  18. Event monitoring of herbicides with naked and membrane-covered Empore disk integrative passive sampling devices.

    PubMed

    Stephens, B Scott; Kapernick, Anita P; Eaglesham, Geoff; Mueller, Jochen F

    2009-08-01

    Subsequent to an initial wet season flood event in the Brisbane River, Australia, both fast (naked disk) and slow (membrane-covered) variants of SDB-RPS Empore disk passive sampling devices were deployed with an automated grab sampling program. A trend increase in the aquatic dissolved concentrations of diuron and simazine was observed over a 10-day period. Kinetic and equilibrium parameters for each sampler were calculated based on the dynamic concentration. Absolute percent difference for duplicate passive samples was <10% in the fast and <25% in the slow samplers. For kinetic sampling, significantly shortened integrative periods are available with the fast compared with the slow variant, with higher sampling rates offering improved detection limits. The study demonstrates a method for determining kinetic parameters of passive samplers in a variable concentration field deployment, and illustrates the differences in quality between active and passive data, in terms of capturing changes in concentration associated with rainfall events. PMID:19520390

  19. A Novel Teflon-membrane Gas Tension Device for Denitrification-studies in Oxygen Minimum Zones

    NASA Astrophysics Data System (ADS)

    Reed, A. C.; McNeil, C. L.; D'Asaro, E. A.; Altabet, M. A.; Johnson, B.; Bourbonnais, A.

    2014-12-01

    Oxygen Minimum Zones (OMZs) are global hotspots for the biogeochemical transformation of biologically-available forms of nitrogen to unusable nitrogen-gas. We present a new Teflon-membrane based Gas Tension Device (GTD) for measuring the excess N2 signal generated by denitrification and anammox in OMZs, with a hydrostatic pressure-independent response and a depth range from 0 - 550 m, a significant advancement from previous GTD models. The GTD consists of a 4/1000" thick by 2" diameter Teflon-membrane with a water-side plenum connected to SeaBird 5T pump. Dissolved gases in the water equilibrate across the membrane with a low-dead-volume housing connected to a high-precision quart pressure sensor. Laboratory data characterizing the GTD will be presented. The e-folding (response) time ranges from 14 min at continuous (100%) pumping to 28 min at pulse (10%) pumping. We also demonstrate the pressure dependence of the partial pressures from Henry's Law in the laboratory for pure nitrogen, pure oxygen, and standard atmospheric ratios of gases. GTD's were field tested on two floats deployed in the Eastern Tropical North Pacific (ETNP) OMZ for 15 days that targeted a productive mesoscale surface eddy originating from the Mexican coast. We anticipated that high organic carbon export should stimulate denitrification within the OMZ below. The floats profiled between the surface and 400 m depth and concurrently measured T, S, PAR, O2 (SBE 43 and Optode), and nitrate (SUNA). The N2-profiles from the GTDs are validated against independently measured N2/Ar ratio data collected during the deployment.

  20. Stabilized liquid membrane device (SLMD) for the passive, integrative sampling of labile metals in water

    USGS Publications Warehouse

    Brumbaugh, W.G.; Petty, J.D.; Huckins, J.N.; Manahan, S.E.

    2002-01-01

    A stabilized liquid membrane device (SLMD) is described for potential use as an in situ, passive, integrative sampler for cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in natural waters. The SLMD (patent pending) consists of a 2.5-cm-wide by 15-cm-long strip of low-density polyethylene (LDPE) layflat tubing containing 1 mL of an equal mixture (v/v) of oleic acid (cis-9-octadecenoic acid) and EMO-8Q (7-[4-ethyl-1-methyloctyl]-8-quinolinol). The reagent mixture continuously diffuses to the exterior surface of the LDPE membrane, and provides for sequestration of several divalent metals for up to several weeks. Depending on sampler configuration, concentration factors of several thousand can be realized for these metal ions after just a few days. In addition to in situ deployment, the SLMD may be useful for laboratory determination of labile metal species in grab samples. Methods for minimizing the effects of water flow on the sampling rate are currently under investigation.

  1. (13) C Breath Tests Are Feasible in Patients With Extracorporeal Membrane Oxygenation Devices.

    PubMed

    Bednarsch, Jan; Menk, Mario; Malinowski, Maciej; Weber-Carstens, Steffen; Pratschke, Johann; Stockmann, Martin

    2016-07-01

    Temporary extracorporeal membrane oxygenation (ECMO) has been established as an essential part of therapy in patients with pulmonary or cardiac failure. As physiological gaseous exchange is artificially altered in this patient group, it is debatable whether a (13) C-breath test can be carried out. In this proof of technical feasibility report, we assess the viability of the (13) C-breath test LiMAx (maximum liver function capacity) in patients on ECMO therapy. All breath probes for the test device were obtained directly via the membrane oxygenator. Data of four patients receiving liver function assessment with the (13) C-breath test LiMAx while having ECMO therapy were analyzed. All results were compared with validated scenarios of the testing procedures. The LiMAx test could successfully be carried out in every case without changing ECMO settings. Clinical course of the patients ranging from multiorgan failure to no sign of liver insufficiency was in accordance with the results of the LiMAx liver function test. The (13) C-breath test is technically feasible in the context of ECMO. Further evaluation of (13) C-breath test in general would be worthwhile. The LiMAx test as a (13) C-breath test accessing liver function might be of particular predictive interest if patients with ECMO therapy develop multiorgan failure. PMID:26527580

  2. Development of a microfluidic device for determination of cell osmotic behavior and membrane transport properties.

    PubMed

    Chen, Hsiu-Hung; Purtteman, Jester J P; Heimfeld, Shelly; Folch, Albert; Gao, Dayong

    2007-12-01

    An understanding of cell osmotic behavior and membrane transport properties is indispensable for cryobiology research and development of cell-type-specific, optimal cryopreservation conditions. A microfluidic perfusion system is developed here to measure the kinetic changes of cell volume under various extracellular conditions, in order to determine cell osmotic behavior and membrane transport properties. The system is fabricated using soft lithography and is comprised of microfluidic channels and a perfusion chamber for trapping cells. During experiments, rat basophilic leukemia (RBL-1 line) cells were injected into the inlet of the device, allowed to flow downstream, and were trapped within a perfusion chamber. The fluid continues to flow to the outlet due to suction produced by a Hamilton Syringe. Two sets of experiments have been performed: the cells were perfused by (1) hypertonic solutions with different concentrations of non-permeating solutes and (2) solutions containing a permeating cryoprotective agent (CPA), dimethylsulfoxide (Me(2)SO), plus non-permeating solute (sodium chloride (NaCl)), respectively. From experiment (1), cell osmotically inactive volume (V(b)) and the permeability coefficient of water (L(p)) for RBL cells are determined to be 41% [n=18, correlation coefficient (r(2)) of 0.903] of original/isotonic volume, and 0.32+/-0.05 microm/min/atm (n=8, r(2)>0.963), respectively, for room temperature (22 degrees C). From experiment (2), the permeability coefficient of water (L(p)) and of Me(2)SO (P(s)) for RBL cells are 0.38+/-0.09 microm/min/atm and (0.49+/-0.13) x 10(-3)cm/min (n=5, r(2)>0.86), respectively. We conclude that this device enables us to: (1) readily monitor the changes of extracellular conditions by perfusing single or a group of cells with prepared media; (2) confine cells (or a cell) within a monolayer chamber, which prevents imaging ambiguity, such as cells overlapping or moving out of the focus plane; (3) study individual cell

  3. [Membrane permeability of brain cell processes after death].

    PubMed

    Agafonov, V A

    1975-07-01

    Experiments were conducted on rats. A study was made of persistence of semipermeability of the membranes of the cell processes of the brain (contraction) with the action of a hypertonic buffer at various periods after death. The membranes of the processes proved to retain the property of semi-permeability even 48 hours after death. Prefixation of the postmortem material in the glutaraldehyde did not influence the sensitivity of the membranes of the processes to the osmotic strength of the surrounding solution. PMID:1227661

  4. Semipermeable membrane devices (SPMDs) as universal environmental monitors for trace contaminants

    SciTech Connect

    Prest, H.F.; Hodgins, M.M.; Jacobson, L.A.; Huckins, J.N.; Petty, J.D.; Brown, J.; Wilson, M.

    1995-12-31

    The vast majority of data complied on trace contaminants in water has been acquired through biomonitoring; using organisms as bioconcentrators of trace substances. A particularly successful and widely applied approach utilizes bivalves in local, national, and international mussel watch programs. Attractive features of this approach are the widespread occurrence of bivalves, their high tolerance and viability, ease of analysis, and high bioconcentration factors for a wide range of compounds. However, uncertainties about uptake, deputation and biotransformation of contaminants convolute the data and make quantitative statements about water concentrations difficult. Recent developments demonstrate semipermeable membrane devices (SPMDs) are a promising new tool for biomonitoring. SPMDs are inexpensive, tolerant of extreme conditions, and concentrations of analytes sequestered by SPMDs can be used to infer bioconcentration potential and average ambient concentrations. The authors present data from freshwater systems such as the San Juan River comparing spatial trends in PAH metabolites in fish bile and PAHs sequestered by SPMDs, and marine environments such as PAHs in SPMDs deployed in Cook Inlet, Alaska. These data support the case for SPMDs as universal monitoring devices or pseudo-organisms that will provide a standardized approach to measuring and monitoring trace contaminants on both local and global scales.

  5. Topographically-patterned porous membranes in a microfluidic device as an in vitro model of renal reabsorptive barriers

    PubMed Central

    Frohlich, Else M.; Alonso, José Luis; Borenstein, Jeffrey T.; Zhang, Xin; Arnaout, M. Amin

    2015-01-01

    Models of reabsorptive barriers require both a means to provide realistic physiologic cues to and quantify transport across a layer of cells forming the barrier. Here we have topographically-patterned porous membranes with several user-defined pattern types. To demonstrate the utility of the patterned membranes, we selected one type of pattern and applied it to a membrane to serve as a cell culture support in a microfluidic model of a renal reabsorptive barrier. The topographic cues in the model resemble physiological cues found in vivo while the porous structure allows quantification of transport across the cell layer. Sub-micron surface topography generated via hot-embossing onto a track-etched polycarbonate membrane, fully replicated topographical features and preserved porous architecture. Pore size and shape were analyzed with SEM and image analysis to determine the effect of hot embossing on pore morphology. The membrane was assembled into a bilayer microfluidic device and a human kidney proximal tubule epithelial cell line (HK-2) and primary renal proximal tubule epithelial cells (RPTEC) were cultured to confluency on the membrane. Immunofluorescent staining of both cell types revealed protein expression indicative of the formation of a reabsorptive barrier responsive to mechanical stimulation: ZO-1 (tight junction), paxillin (focal adhesions) and acetylated α-tubulin (primary cilia). HK-2 and RPTEC aligned in the direction of ridge/groove topography of the membrane in the device, evidence that the device has mechanical control over cell response. This topographically-patterned porous membrane provides an in vitro platform on which to model reabsorptive barriers with meaningful applications for understanding biological transport phenomenon, underlying disease mechanisms, and drug toxicity. PMID:23636129

  6. SCREENING BIOAVAILABLE HYDROPHOBIC TOXICANTS IN SURFACE WATERS WITH SEMIPERMEABLE MEMBRANE DEVICES: ROLE OF INHERENT OLEIC ACID IN TOXICITY EVALUATIONS

    EPA Science Inventory

    Semipermeable membrane devices (SPMDs) were deployed for 4 weeks in two rivers in Lithuania, The SPMD dialysates were tested in the Microtox assay and, surprisingly, the sample from the relatively clean (U) over bar la River exhibited three times more toxicity than the sample fro...

  7. Membrane Protein Incorporation into Nano-Bioelectronics: An insight into Rhodopsin Controlled SiNW-FET Devices

    NASA Astrophysics Data System (ADS)

    Tunuguntla, Ramya

    Biological systems use different energy sources to interact with their environments by creating ion gradients, membrane electric potentials, or a proton motive force to accomplish strikingly complex tasks on the nanometer length scale, such as energy harvesting, and whole organism replication. Most of this activity involves a vast arsenal of active and passive ion channels, membrane receptors and ion pumps that mediate complex and precise transport across biological membranes. Despite the remarkable rate of progress exhibited by modern microelectronic devices, they still cannot compete with the efficiency and precision of biological systems on the component level. At the same time, the sophistication of these molecular machines provides an excellent opportunity to use them in hybrid bioelectronic devices where such a combination could deliver enhanced electronic functionality and enable seamless bi-directional interfaces between man-made and biological assemblies. Artificial membrane systems allow researchers to study the structure and function of membrane proteins in a matrix that approximates their natural environment and to integrate these proteins in ex-vivo devices such as electronic biosensors, thin-film protein arrays, or bio-fuel cells. Since most membrane proteins have vectorial functions, both functional studies and applications require effective control over protein orientation within a lipid bilayer. In our work, we have explored the role of the bilayer surface charge in determining transmembrane protein orientation and functionality during formation of proteoliposomes. We reconstituted a model vectorial ion pump, proteorhodopsin, in liposomes of opposite charges and varying charge densities and determined the resultant protein orientation. Antibody-binding assay and proteolysis of proteoliposomes showed physical evidence of preferential orientation, and functional assays verified vectorial nature of ion transport in this system. Our results indicate

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

    SciTech Connect

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

    1994-08-01

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

  9. Semipermeable-membrane devices as an in situ and laboratory testing chamber

    SciTech Connect

    Gardiner, W.W.; Word, J.Q.

    1995-12-31

    The use of semipermeable-membrane devices (SPMDs) to measure the bioavailability of dissolved (< 10{angstrom}) hydrophobic-organic-compounds has recently been established. These low-density polyethylene bags are effective and relatively easy in situ devices for evaluating bioaccumulation potentials of polyaromatic hydrocarbons, pesticides, polychlorinated biphenyls, and dioxins. The authors believe SPMDs may also be effective in situ and laboratory testing chambers for evaluating dissolved contaminant effects on sensitive life stages of freshwater/marine fish and invertebrates. Applications may include dissolved contaminant toxicity of effluents, porewater, water-column, and surface microlayer. In laboratory tests, the applicability of SPMD-testing chambers was explored with marine bivalve larvae (Mytilus galloprovincialis). Test solutions were filtered seawater, dissolved copper, ammonia, and an elutriate preparation that included both organic and inorganic contaminants. SPMDs were filled with seawater, immersed in test solutions for 24-h, then spiked with fertilized M. galloprovincialis embryos. Following 48-h exposures, >90% survival and normal development was observed in the controls, indicating that incubation in the SPMDs did not adversely affect larval development. Incubation in test treatments resulted in slight, but not significantly different, reductions in normal development, relative to the controls. The authors believe longer SPMD immersion prior to testing will likely be required to allow SPMD contents to reach equilibrium with test solutions before eliciting a significant toxicological response. While this may limit the application of SPMDs for short term in situ exposures, they may be used for field/laboratory exposures of a week or more or for collecting equilibrated field samples for laboratory testing.

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

    USGS Publications Warehouse

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

    2009-01-01

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

  11. Sequestration of priority pollutant PAHs from sediment pore water employing semipermeable membrane devices.

    PubMed

    Williamson, Kelly S; Petty, Jimmie D; Huckins, James N; Lebo, Jon A; Kaiser, Edwin M

    2002-11-01

    Semipermeable membrane devices (SPMDs) were employed to sample sediment pore water in static exposure studies under controlled laboratory conditions using (control pond and formulated) sediments fortified with 15 priority pollutant polycyclic aromatic hydrocarbons (PPPAHs). The sediment fortification level of 750 ng/g was selected on the basis of what might be detected in a sediment sample from a contaminated area. The sampling interval consisted of 0, 4, 7, 14, and 28 days for each study. The analytical methodologies, as well as the extraction and sample cleanup procedures used in the isolation, characterization, and quantitation of 15 PPPAHs at different fortification levels in SPMDs, water, and sediment were reported previously (Williamson, M.S. Thesis, University of Missouri-Columbia, USA; Williamson et al., Chemosphere (This issue--PII: S0045-6535(02)00394-6)) and used for this project. Average (mean) extraction recoveries for each PPPAH congener in each matrix are reported and discussed. No procedural blank extracts (controls) were found to contain any PPPAH residues above the method quantitation limit, therefore, no matrix interferences were detected. The focus of this publication is to demonstrate the ability to sequester environmental contaminants, specifically PPPAHs, from sediment pore water using SPMDs and two different types of fortified sediment. PMID:12431008

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

    NASA Astrophysics Data System (ADS)

    Cranor, Walter L.; Alvarez, David A.; Huckins, James N.; Petty, Jimmie D.

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

  13. Sequestration of priority pollutant PAHs from sediment pore water employing semipermeable membrane devices

    USGS Publications Warehouse

    Williamson, K.S.; Petty, J.D.; Huckins, J.N.; Lebo, J.A.; Kaiser, E.M.

    2002-01-01

    Semipermeable membrane devices (SPMDs) were employed to sample sediment pore water in static exposure studies under controlled laboratory conditions using (control pond and formulated) sediments fortified with 15 priority pollutant polycyclic aromatic hydrocarbons (PPPAHs). The sediment fortification level of 750 ng/g was selected on the basis of what might be detected in a sediment sample from a contaminated area. The sampling interval consisted of 0, 4, 7, 14, and 28 days for each study. The analytical methodologies, as well as the extraction and sample cleanup procedures used in the isolation, characterization, and quantitation of 15 PPPAHs at different fortification levels in SPMDs, water, and sediment were reported previously (Williamson, M.S. Thesis, University of Missouri - Columbia, USA; Williamson et al., Chemosphere (This issue - PII: S0045-6535(02)00394-6)) and used for this project. Average (mean) extraction recoveries for each PPPAH congener in each matrix are reported and discussed. No procedural blank extracts (controls) were found to contain any PPPAH residues above the method quantitation limit, therefore, no matrix interferences were detected. The focus of this publication is to demonstrate the ability to sequester environmental contaminants, specifically PPPAHs, from sediment pore water using SPMDs and two different types of fortified sediment.

  14. Evaluation of persistent hydrophobic organic compounds in the Columbia River Basin using semipermeable-membrane devices

    USGS Publications Warehouse

    McCarthy, K.A.; Gale, R.W.

    2001-01-01

    Persistent hydrophobic organic compounds are of concern in the Columbia River because they have been correlated with adverse effects on wildlife. We analysed samples from nine main-stem and six tributary sites throughout the Columbia River Basin (Washington and Oregon) for polychlorinated dibenzo-p-dioxins, dibenzofurans, polychlorinated biphenyls, organochlorine pesticides, and priority-pollutant polycyclic aromatic hydrocarbons. Because these compounds may have important biological consequences at aqueous concentrations well below the detection limits associated with conventional sampling methods, we used semipermeable-membrane devices to sample water and achieved parts-per-quintillion detection limits. All of these compound classes were prevalent within the basin, but concentrations of many analytes were highest in the vicinity of Portland-Vancouver, indicating that the Willamette subbasin-and perhaps the urban area in particular-is an important source of these compounds. Data collected during basin low-flow conditions in 1997 and again during basin high-flow conditions in 1998 indicate that in-stream processes such as dilution by relatively clean inflow, and flow through island hyporheic zones may be important mechanisms for attenuating dissolved concentrations of hydrophobic compounds.

  15. Low-temperature bonded glass-membrane microfluidic device for in vitro organ-on-a-chip cell culture models

    NASA Astrophysics Data System (ADS)

    Pocock, Kyall J.; Gao, Xiaofang; Wang, Chenxi; Priest, Craig; Prestidge, Clive A.; Mawatari, Kazuma; Kitamori, Takehiko; Thierry, Benjamin

    2015-12-01

    The integration of microfluidics with living biological systems has paved the way to the exciting concept of "organson- a-chip", which aims at the development of advanced in vitro models that replicate the key features of human organs. Glass based devices have long been utilised in the field of microfluidics but the integration of alternative functional elements within multi-layered glass microdevices, such as polymeric membranes, remains a challenge. To this end, we have extended a previously reported approach for the low-temperature bonding of glass devices that enables the integration of a functional polycarbonate porous membrane. The process was initially developed and optimised on specialty low-temperature bonding equipment (μTAS2001, Bondtech, Japan) and subsequently adapted to more widely accessible hot embosser units (EVG520HE Hot Embosser, EVG, Austria). The key aspect of this method is the use of low temperatures compatible with polymeric membranes. Compared to borosilicate glass bonding (650 °C) and quartz/fused silica bonding (1050 °C) processes, this method maintains the integrity and functionality of the membrane (Tg 150 °C for polycarbonate). Leak tests performed showed no damage or loss of integrity of the membrane for up to 150 hours, indicating sufficient bond strength for long term cell culture. A feasibility study confirmed the growth of dense and functional monolayers of Caco-2 cells within 5 days.

  16. Comparing the Accumulation of PCBs by Passive Samplers and Mussels from the Water Column at a Contaminated Sediment Site

    EPA Science Inventory

    Passive samplers, including semi-permeable membrane devices (SPMDs), solid phase microextraction (SPME) and polyethylene devices (PEDs), provide innovative tools for measuring hydrophobic organic contaminants (HOCs) originating from contaminated waters and sediments. Because the...

  17. Evaluating PCB Bioavailability Using Passive Samplers and Mussles at a Contaminated Sediment Site

    EPA Science Inventory

    Passive samplers, including semi-permeable membrane devices (SPMDs), solid phase microextraction (SPME) and polyethylene devices (PEDs), provide innovative tools for measuring hydrophobic organic contaminants (HOCs) originating from contaminated waters and sediments. Because the...

  18. Quantification of the specific membrane capacitance of single cells using a microfluidic device and impedance spectroscopy measurement.

    PubMed

    Tan, Qingyuan; Ferrier, Graham A; Chen, Brandon K; Wang, Chen; Sun, Yu

    2012-09-01

    The specific membrane capacitance (SMC) is an electrical parameter that correlates with both the electrical activity and morphology of the plasma membrane, which are physiological markers for cellular phenotype and health. We have developed a microfluidic device that enables impedance spectroscopy measurements of the SMC of single biological cells. Impedance spectra induced by single cells aspirated into the device are captured over a moderate frequency range (5 kHz-1 MHz). Maximum impedance sensitivity is achieved using a tapered microfluidic channel, which effectively routes electric fields across the cell membranes. The SMC is extracted by curve-fitting impedance spectra to an equivalent circuit model. From our measurement, acute myeloid leukemia (AML) cells are found to exhibit larger SMC values in hypertonic solutions as compared with those in isotonic solutions. In addition, AML cell phenotypes (AML2 and NB4) exhibiting varying metastatic potential yield distinct SMC values (AML2: 16.9 ± 1.9 mF/m(2) (n = 23); NB4: 22.5 ± 4.7 mF/m(2) (n = 23)). Three-dimensional finite element simulations of the microfluidic device confirm the feasibility of this approach. PMID:23940502

  19. Lab-on-a-Membrane Foldable Devices for Duplex Drop-Volume Electrochemical Biosensing Using Quantum Dot Tags.

    PubMed

    Kokkinos, Christos; Angelopoulou, Michailia; Economou, Anastasios; Prodromidis, Mamas; Florou, Ageliki; Haasnoot, Willem; Petrou, Panagiota; Kakabakos, Sotirios

    2016-07-01

    This work describes a new type of integrated lab-on-a-membrane foldable device suitable for on-site duplex electrochemical biosensing using drop-size sample volumes. The devices are fabricated entirely by screen-printing on a nylon membrane and feature two assay zones which are located symmetrically on either side of a three-electrode voltammetric cell with a bismuth citrate-loaded graphite working electrode. After the completion of two spatially separated drop-volume competitive immunoassays on the assay zones using biotinylated antibodies labeled with streptavidin-conjugated Pb- and Cd-based quantum dots (QDs), respectively, the QD labels are dissolved releasing Pb(II) and Cd(II) in the assay zones. Then, the two assay zones are folded over, and they are brought in contact with the voltammetric cell for simultaneous anodic stripping voltammetric (ASV) determination of Pb(II) and Cd(II) at the bismuth nanostructured layer formed on the working electrode by reduction of the bismuth citrate during the preconcentration step. The fabrication of the devices is discussed in detail, and their operational characteristics are exhaustively studied. In order to demonstrate their applicability to the analysis in complex matrices, duplex ASV-QDs-based determination of bovine casein and bovine immunoglobulin G is carried out in milk samples yielding limits of detection of 0.04 μg mL(-1) and 0.02 μg mL(-1), respectively. The potential of the devices to detect milk adulteration is further demonstrated. These new membrane devices enable duplex biosensing with distinct advantages over existing approaches in terms of cost, fabrication, and operational simplicity and rapidity, portability, sample size, disposability, sensitivity, and suitability for field analysis. PMID:27257985

  20. Method for dialysis on microchips using thin porous polymer membrane

    DOEpatents

    Singh, Anup K.; Kirby, Brian J.; Shepodd, Timothy J.

    2009-05-19

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and forms a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  1. Dialysis on microchips using thin porous polymer membranes

    DOEpatents

    Singh, Anup K.; Kirby, Brian J.; Shepodd, Timothy J.

    2007-09-04

    Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and form a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.

  2. Membrane microdomains: from seeing to understanding

    PubMed Central

    Truong-Quang, Binh-An; Lenne, Pierre-François

    2014-01-01

    The plasma membrane is a composite material, which forms a semi-permeable barrier and an interface for communication between the intracellular and extracellular environments. While the existence of membrane microdomains with nanoscale organization has been proved by the application of numerous biochemical and physical methods, direct observation of these heterogeneities using optical microscopy has remained challenging for decades, partly due to the optical diffraction limit, which restricts the resolution to ~200 nm. During the past years, new optical methods which circumvent this fundamental limit have emerged. Not only do these techniques allow direct visualization, but also quantitative characterization of nanoscopic structures. We discuss how these emerging optical methods have refined our knowledge of membrane microdomains and how they may shed light on the basic principles of the mesoscopic membrane organization. PMID:24600455

  3. Surgical Membranes as Directional Delivery Devices to Generate Tissue: Testing in an Ovine Critical Sized Defect Model

    PubMed Central

    Knothe Tate, Melissa L.; Chang, Hana; Moore, Shannon R.; Knothe, Ulf R.

    2011-01-01

    Purpose Pluripotent cells residing in the periosteum, a bi-layered membrane enveloping all bones, exhibit a remarkable regenerative capacity to fill in critical sized defects of the ovine femur within two weeks of treatment. Harnessing the regenerative power of the periosteum appears to be limited only by the amount of healthy periosteum available. Here we use a substitute periosteum, a delivery device cum implant, to test the hypothesis that directional delivery of endogenous periosteal factors enhances bone defect healing. Methods Newly adapted surgical protocols were used to create critical sized, middiaphyseal femur defects in four groups of five skeletally mature Swiss alpine sheep. Each group was treated using a periosteum substitute for the controlled addition of periosteal factors including the presence of collagen in the periosteum (Group 1), periosteum derived cells (Group 2), and autogenic periosteal strips (Group 3). Control group animals were treated with an isotropic elastomer membrane alone. We hypothesized that periosteal substitute membranes incorporating the most periosteal factors would show superior defect infilling compared to substitute membranes integrating fewer factors (i.e. Group 3>Group 2>Group 1>Control). Results Based on micro-computed tomography data, bone defects enveloped by substitute periosteum enabling directional delivery of periosteal factors exhibit superior bony bridging compared to those sheathed with isotropic membrane controls (Group 3>Group 2>Group 1, Control). Quantitative histological analysis shows significantly increased de novo tissue generation with delivery of periosteal factors, compared to the substitute periosteum containing a collagen membrane alone (Group 1) as well as compared to the isotropic control membrane. Greatest tissue generation and maximal defect bridging was observed when autologous periosteal transplant strips were included in the periosteum substitute. Conclusion Periosteum-derived cells as well

  4. Membrane stabilizer

    DOEpatents

    Mingenbach, William A.

    1988-01-01

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

  5. Use of mussels and semipermeable membrane devices to assess bioavailability of residual polynuclear aromatic hydrocarbons three years after the Exxon Valdez oil spill

    SciTech Connect

    Shigenaka, G.; Henry, C.B. Jr.

    1995-12-31

    Mussels (Mytilus cf. trossulus) were transplanted to a heavily oiled and extensively treated site on Smith Island, Prince William Sound, Alaska, in 1992. A new monitoring and assessment tool, the semipermeable membrane device, was also deployed to compare hydrocarbon uptake with mussels and to evaluate the route of exposure to mussels. Both mussels and semipermeable membrane devices accumulated polynuclear aromatic hydrocarbons during 14- and 52-day deployments, particularly at the oiled site. Accumulation levels were similar between mussels and the semipermeable membrane devices, but the distribution of individual hydrocarbons differed. The results permit some inference about route of exposure to mussels. Sheens leaching from subsurface deposits of residual oil, and particulate material with adsorbed hydrocarbons were apparently more important exposure pathways than dissolved hydrocarbons in water. Semipermeable membrane devices show promise as monitoring tools and to provide insights into exposure pathways for biota. 20 refs., 7 figs., 4 tabs.

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

    PubMed

    2016-02-12

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

  7. UV-Induced Radical Photo-Polymerization: A Smart Tool for Preparing Polymer Electrolyte Membranes for Energy Storage Devices

    PubMed Central

    Nair, Jijeesh R.; Chiappone, Annalisa; Destro, Matteo; Jabbour, Lara; Meligrana, Giuseppina; Gerbaldi, Claudio

    2012-01-01

    In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or nanoscale microfibrillated cellulose fibers are also demonstrated. The ionic conductivity of the various prepared membranes is very high, with average values approaching 10-3 S cm-1 at ambient temperature. The electrochemical stability window is wide (anodic breakdown voltages > 4.5 V vs. Li in all the cases) along with good cyclability in lithium cells at ambient temperature. The galvanostatic cycling tests are conducted by constructing laboratory-scale lithium cells using LiFePO4 as cathode and lithium metal as anode with the selected polymer electrolyte membrane as the electrolyte separator. The results obtained demonstrate that UV induced radical photo-polymerization is a well suited method for an easy and rapid preparation of easy tunable quasi-solid polymer electrolyte membranes for energy storage devices. PMID:24958425

  8. UV-Induced Radical Photo-Polymerization: A Smart Tool for Preparing Polymer Electrolyte Membranes for Energy Storage Devices

    PubMed Central

    Nair, Jijeesh R.; Chiappone, Annalisa; Destro, Matteo; Jabbour, Lara; Zeng, Juqin; Lupo, Francesca Di; Garino, Nadia; Meligrana, Giuseppina; Francia, Carlotta; Gerbaldi, Claudio

    2012-01-01

    In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or nanoscale microfibrillated cellulose fibers are also demonstrated. The ionic conductivity of the various prepared membranes is very high, with average values approaching 10−3 S cm−1 at ambient temperature. The electrochemical stability window is wide (anodic breakdown voltages > 4.5 V vs. Li in all the cases) along with good cyclability in lithium cells at ambient temperature. The galvanostatic cycling tests are conducted by constructing laboratory-scale lithium cells using LiFePO4 as cathode and lithium metal as anode with the selected polymer electrolyte membrane as the electrolyte separator. The results obtained demonstrate that UV induced radical photo-polymerization is a well suited method for an easy and rapid preparation of easy tunable quasi-solid polymer electrolyte membranes for energy storage devices. PMID:24958178

  9. UV-Induced Radical Photo-Polymerization: A Smart Tool for Preparing Polymer Electrolyte Membranes for Energy Storage Devices.

    PubMed

    Nair, Jijeesh R; Chiappone, Annalisa; Destro, Matteo; Jabbour, Lara; Zeng, Juqin; Di Lupo, Francesca; Garino, Nadia; Meligrana, Giuseppina; Francia, Carlotta; Gerbaldi, Claudio

    2012-01-01

    In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or nanoscale microfibrillated cellulose fibers are also demonstrated. The ionic conductivity of the various prepared membranes is very high, with average values approaching 10-3 S cm-1 at ambient temperature. The electrochemical stability window is wide (anodic breakdown voltages > 4.5 V vs. Li in all the cases) along with good cyclability in lithium cells at ambient temperature. The galvanostatic cycling tests are conducted by constructing laboratory-scale lithium cells using LiFePO4 as cathode and lithium metal as anode with the selected polymer electrolyte membrane as the electrolyte separator. The results obtained demonstrate that UV induced radical photo-polymerization is a well suited method for an easy and rapid preparation of easy tunable quasi-solid polymer electrolyte membranes for energy storage devices. PMID:24958178

  10. UV-Induced Radical Photo-Polymerization: A Smart Tool for Preparing Polymer Electrolyte Membranes for Energy Storage Devices.

    PubMed

    Nair, Jijeesh R; Chiappone, Annalisa; Destro, Matteo; Jabbour, Lara; Meligrana, Giuseppina; Gerbaldi, Claudio

    2012-01-01

    In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or nanoscale microfibrillated cellulose fibers are also demonstrated. The ionic conductivity of the various prepared membranes is very high, with average values approaching 10-3 S cm-1 at ambient temperature. The electrochemical stability window is wide (anodic breakdown voltages > 4.5 V vs. Li in all the cases) along with good cyclability in lithium cells at ambient temperature. The galvanostatic cycling tests are conducted by constructing laboratory-scale lithium cells using LiFePO4 as cathode and lithium metal as anode with the selected polymer electrolyte membrane as the electrolyte separator. The results obtained demonstrate that UV induced radical photo-polymerization is a well suited method for an easy and rapid preparation of easy tunable quasi-solid polymer electrolyte membranes for energy storage devices. PMID:24958425

  11. Development of the permeability/performance reference compound approach for in situ calibration of semipermeable membrane devices

    USGS Publications Warehouse

    Huckins, J.N.; Petty, J.D.; Lebo, J.A.; Almeida, F.V.; Booij, K.; Alvarez, D.A.; Cranor, W.L.; Clark, R.C.; Mogensen, B.B.

    2002-01-01

    Permeability/performance reference compounds (PRCs) are analytically noninterfering organic compounds with moderate to high fugacity from semipermeable membrane devices (SPMDs) that are added to the lipid prior to membrane enclosure. Assuming that isotropic exchange kinetics (IEK) apply and that SPMD-water partition coefficients are known, measurement of PRC dissipation rate constants during SPMD field exposures and laboratory calibration studies permits the calculation of an exposure adjustment factor (EAF). In theory, PRC-derived EAF ratios reflect changes in SPMD sampling rates (relative to laboratory data) due to differences in exposure temperature, membrane biofouling, and flow velocity-turbulence at the membrane surface. Thus, the PRC approach should allow for more accurate estimates of target solute/vapor concentrations in an exposure medium. Under some exposure conditions, the impact of environmental variables on SPMD sampling rates may approach an order of magnitude. The results of this study suggest that most of the effects of temperature, facial velocity-turbulence, and biofouling on the uptake rates of analytes with a wide range of hydrophobicities can be deduced from PRCs with a much narrower range of hydrophobicities. Finally, our findings indicate that the use of PRCs permits prediction of in situ SPMD sampling rates within 2-fold of directly measured values.

  12. Membrane-based microchannel device for continuous quantitative extraction of dissolved free sulfide from water and from oil.

    PubMed

    Toda, Kei; Ebisu, Yuki; Hirota, Kazutoshi; Ohira, Shin-Ichi

    2012-09-01

    Underground fluids are important natural sources of drinking water, geothermal energy, and oil-based fuels. To facilitate the surveying of such underground fluids, a novel microchannel extraction device was investigated for in-line continuous analysis and flow injection analysis of sulfide levels in water and in oil. Of the four designs investigated, the honeycomb-patterned microchannel extraction (HMCE) device was found to offer the most effective liquid-liquid extraction. In the HMCE device, a thin silicone membrane was sandwiched between two polydimethylsiloxane plates in which honeycomb-patterned microchannels had been fabricated. The identical patterns on the two plates were accurately aligned. The extracted sulfide was detected by quenching monitoring of fluorescein mercuric acetate (FMA). The sulfide extraction efficiencies from water and oil samples of the HMCE device and of three other designs (two annular and one rectangular channel) were examined theoretically and experimentally. The best performance was obtained with the HMCE device because of its thin sample layer (small diffusion distance) and large interface area. Quantitative extraction from both water and oil could be obtained using the HMCE device. The estimated limit of detection for continuous monitoring was 0.05 μM, and sulfide concentrations in the range of 0.15-10 μM could be determined when the acceptor was 5 μM FMA alkaline solution. The method was applied to natural water analysis using flow injection mode, and the data agreed with those obtained using headspace gas chromatography-flame photometric detection. The analysis of hydrogen sulfide levels in prepared oil samples was also performed. The proposed device is expected to be used for real time survey of oil wells and groundwater wells. PMID:22840703

  13. Assessment of mitochondrial membrane potential using an on-chip microelectrode in a microfluidic device

    PubMed Central

    Dávila, Antonio; Wallace, Douglas C.; Burke, Peter

    2010-01-01

    The mitochondrial membrane potential is used to generate and regulate energy in living systems, driving the conversion of ADP to ATP, regulating ion homeostasis, and controlling apoptosis, all central to human health and disease. Therefore, there is a need for tools to study its regulation in a controlled environment for potential clinical and scientific applications. For this aim, an on-chip tetraphenylphosphonium (TPP+) selective microelectrode sensor was constructed in a microfluidic environment. The concentration of isolated mitochondria (Heb7A) used in a membrane potential measurement was 0.3 ng μL−1, four orders of magnitude smaller than the concentration used in conventional assays (3 μg μL−1). In addition, the volume of the chamber (85 μL) is 2 orders of magnitude smaller than traditional experiments. As a demonstration, changes in the membrane potential are clearly measured in response to a barrage of well-known substrates and inhibitors of the electron transport chain. This general approach, which to date has not been demonstrated for study of mitochondrial function and bio-energetics in generally, can be instrumental in advancing the field of mitochondrial research and clinical applications by allowing high throughput studies of the regulation, dynamics, and statistical properties of the mitochondrial membrane potential in response to inhibitors and inducers of apoptosis in a controlled (microfluidic) chemical environment. PMID:20383402

  14. A Feasibility Study of Pressure Retarded Osmosis Power Generation System based on Measuring Permeation Volume using Reverse Osmosis Membrane

    NASA Astrophysics Data System (ADS)

    Enomoto, Hiroshi; Fujitsuka, Masashi; Hasegawa, Tomoyasu; Kuwada, Masatoshi; Tanioka, Akihiko; Minagawa, Mie

    Pressure Retarded Osmosis (PRO) power generation system is a hydroelectric power system which utilize permeation flow through a semi-permeable membrane. Permeation flow is generated by potential energy of salinity difference between sea water and fresh water. As membrane cost is expensive, permeation performance of membrane must be higher to realize PRO system. We have investigated Reverse Osmosis (RO) membrane products as semi-permeable membrane and measured permeation volume of a few products. Generation power by membrane area calculated from permeation volume is about 0.62W/m2. But by our improvements (more salt water volume, spacer of fresh water channel with a function of discharging concentrated salinity, extra low pressure type of membrane, washing support layer of membrane when generation power reduces to half), generation power may be 2.43W/m2. Then power system cost is about 4.1 million yen/kW. In addition, if support layer of membrane makes thinner and PRO system is applied to the equipment that pumping power on another purpose is avairable (wastewater treatment plant located at the seaside, thermal and nuclear power plant or sea water desalination plant), generation power may be more. By these improvements PRO system may be able to realize at the cost close to photovoltaic power system.

  15. Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2011-01-01

    A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to 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 development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a 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 bed design further leverages a sorbent developed for ISS that introduces 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 clear 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.

  16. Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Rector, Tony; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2012-01-01

    A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to 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 water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a 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 process further leverages a sorbent developed for ISS that introduces 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. This

  17. Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2012-01-01

    A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to 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 development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a 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 Transport Water Loop. The bed design further leverages a sorbent developed for the ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System. 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 crewed spaceflight Environmental Control and Life Support System hardware.

  18. Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2013-01-01

    A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to 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 development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a 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 bed design further leverages a sorbent developed for ISS that introduces 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.

  19. Integrated SDS removal and protein digestion by hollow fiber membrane based device for SDS-assisted proteome analysis.

    PubMed

    Xia, Simin; Yuan, Huiming; Chen, Yuanbo; Liang, Zheng; Zhang, Lihua; Zhang, Yukui

    2015-08-15

    In this work, a novel integrated sample preparation device for SDS-assisted proteome analysis was developed, by which proteins dissolved in 4% (w/v) SDS were first diluted by 50% methanol, and then SDS was online removed by a hollow fiber membrane interface (HFMI) with 50mM ammonium bicarbonate (pH 8.0) as an exchange buffer, finally digested by an immobilized enzyme reactor (IMER). To evaluate the performance of such an integrated device, bovine serum albumin dissolved in 4% (w/v) SDS as a model sample was analyzed; it could be found that similar to that obtained by direct analysis of BSA digests without SDS (the sequence coverage of 60.3±1.0%, n=3), with HFMI as an interface for SDS removal, BSA was identified with the sequence coverage of 61.0±1.0% (n=3). However, without SDS removal by HFMI, BSA could not be digested by the IMER and none peptides could be detected. In addition, such an integrated sample preparation device was also applied for the analysis of SDS extracted proteins from rat brain, compared to those obtained by filter-aided sample preparation (FASP), not only the identified protein group and unique peptide number were increased by 12% and 39% respectively, but also the sample pretreatment time was shortened from 24h to 4h. All these results demonstrated that such an integrated sample preparation device would provide an alternative tool for SDS assisted proteome analysis. PMID:25966408

  20. Realizing Synchronous Energy Harvesting and Ion Separation with Graphene Oxide Membranes

    NASA Astrophysics Data System (ADS)

    Sun, Pengzhan; Zheng, Feng; Zhu, Miao; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Zhu, Hongwei

    2014-07-01

    A synchronous ion separation and electricity generation process has been developed using G-O membranes. In addition to the size effect proposed prevsiouly, the separation of ions can be attributed to the different interactions between ions and G-O membranes; the generation of electricity is due to the confinement of G-O membranes, and the mobility difference of ions. Efficient energy transduction has been achieved with G-O membranes, converting magnetic, thermal and osmotic energy to electricity, distinguishing this material from other commercial semi-permeable membranes. Our study indicated that G-O membranes could find potential applications in the purification of wastewater, while producing electricity simultaneously. With G-O membranes, industrial magnetic leakage and waste heat could also be used to produce electricity, affording a superior approach for energy recovery.

  1. Realizing synchronous energy harvesting and ion separation with graphene oxide membranes.

    PubMed

    Sun, Pengzhan; Zheng, Feng; Zhu, Miao; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Zhu, Hongwei

    2014-01-01

    A synchronous ion separation and electricity generation process has been developed using G-O membranes. In addition to the size effect proposed prevsiouly, the separation of ions can be attributed to the different interactions between ions and G-O membranes; the generation of electricity is due to the confinement of G-O membranes, and the mobility difference of ions. Efficient energy transduction has been achieved with G-O membranes, converting magnetic, thermal and osmotic energy to electricity, distinguishing this material from other commercial semi-permeable membranes. Our study indicated that G-O membranes could find potential applications in the purification of wastewater, while producing electricity simultaneously. With G-O membranes, industrial magnetic leakage and waste heat could also be used to produce electricity, affording a superior approach for energy recovery. PMID:24984782

  2. Realizing Synchronous Energy Harvesting and Ion Separation with Graphene Oxide Membranes

    PubMed Central

    Sun, Pengzhan; Zheng, Feng; Zhu, Miao; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Zhu, Hongwei

    2014-01-01

    A synchronous ion separation and electricity generation process has been developed using G-O membranes. In addition to the size effect proposed prevsiouly, the separation of ions can be attributed to the different interactions between ions and G-O membranes; the generation of electricity is due to the confinement of G-O membranes, and the mobility difference of ions. Efficient energy transduction has been achieved with G-O membranes, converting magnetic, thermal and osmotic energy to electricity, distinguishing this material from other commercial semi-permeable membranes. Our study indicated that G-O membranes could find potential applications in the purification of wastewater, while producing electricity simultaneously. With G-O membranes, industrial magnetic leakage and waste heat could also be used to produce electricity, affording a superior approach for energy recovery. PMID:24984782

  3. A computer simulation study of the separation of aqueous solutions using thin zeolite membranes

    NASA Astrophysics Data System (ADS)

    Lin, J.; Murad, S.

    2001-07-01

    A recently developed molecular simulation scheme for studying solutions undergoing osmosis and reverse osmosis was used to study the separation of aqueous solutions using thin zeolite membranes. This method allows for the preservation of the atomic roughness of the membranes, while the molecules that constitute the membranes are also allowed to vibrate. In the simulations, two thin membranes cut from a cubic cell of ZK-4 zeolite were used as the semi-permeable membranes to separate water from aqueous NaCl solutions. Both osmosis and reverse-osmosis phenomena were observed. The study showed that ZK-4 zeolite membranes show promise for use in membrane-based separation of aqueous electrolyte solutions, as well as other similar systems.

  4. Membrane stabilizer

    DOEpatents

    Mingenbach, W.A.

    1988-02-09

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

  5. Fast isolation of hydrophobic organic environmental contaminants from exposed semipermeable membrane devices (SPMDs) prior to GC analysis.

    PubMed

    Setková, Lucie; Hajslová, Jana; Bergqvist, Per-Anders; Kocourek, Vladimír; Kazda, Radek; Suchan, Petr

    2005-10-28

    Semipermeable membrane devices (SPMD) represent a passive sampling technology that is becoming widely used for monitoring of surface waters pollution. While "classic" procedures employ dialysis to recover target compounds from exposed SPMDs, in the present study analytes were isolated from cut membrane together with sequestering medium (triolein) using hexane as an extraction solvent. This approach allowed us to reduce the time needed for accomplishment of isolation step from 48 h to only 1 h. Automated gel permeation chromatography (GPC) clean-up is employed in the following step to separate triolein from analytes fraction. Musk compounds (MCs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and several other persistent organochlorine compounds (OCs) were determined in the respective fraction by GC method employing selective detectors (MSD, ECD). As shown in a series of analyses of SPMDs deployed in various aquatic ecosystems, high recoveries and good repeatability of results together with a possibility to obtain the information on the pollution of sampling site at the day of sample arrival to laboratory make this newly implemented procedure an interesting alternative to time consuming dialysis. PMID:16199223

  6. Potential Usage of Thermoelectric Devices in a High-Temperature Polymer Electrolyte Membrane (PEM) Fuel Cell System: Two Case Studies

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Chen, Min; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2012-06-01

    Methanol-fueled, high-temperature polymer electrolyte membrane fuel cell (HTPEMFC) power systems are promising as the next generation of vehicle engines, efficient and environmentally friendly. Currently, their performance still needs to be improved, and they still rely on a large Li-ion battery for system startup. In this article, to handle these two issues, the potential of thermoelectric (TE) devices applied in a HTPEMFC power system has been preliminarily evaluated. First, right after the fuel cell stack or the methanol reformer, thermoelectric generators (TEGs) are embedded inside a gas-liquid heat exchanger to form a heat recovery subsystem jointly for electricity production. It is calculated that the recovered power can increase the system efficiency and mitigate the dependence on Li-ion battery during system startup. To improve the TEG subsystem performance, a finite-difference model is then employed and two main parameters are identified. Second, TE coolers are integrated into the methanol steam reformer to regulate heat fluxes herein and improve the system dynamic performance. Similar modification is also done on the evaporator to improve its dynamic performance as well as to reduce the heat loss during system startup. The results demonstrate that the TE-assisted heat flux regulation and heat-loss reduction can also effectively help solve the abovementioned two issues. The preliminary analysis in this article shows that a TE device application inside HTPEMFC power systems is of great value and worthy of further study.

  7. Bioacceptable and calcification-resistant membranes and interfaces for implantable sensors and devices

    NASA Astrophysics Data System (ADS)

    Galeska, Izabela Ewa

    The rational design and characterization of biocompatible, semipermeable and calcification resistant materials to serve as an outer membrane for implantable glucose biosensors, was the primary focus of this research. Multilayered films of polyanions (i.e. Nafion(TM), a perfluorinated ionomer, and Humic Acids (HAs), naturally occurring biopolymers), fabricated by layer-by-layer self-assembly with oppositely charged ferric ions were investigated as potential membranes. Spectroscopic ellipsometry and quartz crystal microbalance studies point towards a stepwise film growth, with growth rates of 47 and 24.3 nm per layer (for Nafion and HAs respectively) that can be altered depending on the pH and ionic strength of the polyanion solution. Nafion/Fe3+ assembled films exhibited an order of magnitude lower calcification as compared to dip-coated Nafion films and did not require annealing to impart insolubility. Similarly the HAs/Fe3+ films were also devoid of calcification, even after four-week immersion in DMEM cell culture media. Significantly, in vivo studies on the HAs/Fe3 films point to their biocompatibility as demonstrated by mild tissue reaction. These results, along with controllable glucose permeability, could prove vital in prolonging the lifetime of implantable biosensors. Additionally in effort to minimize tissue trauma upon implantation, novel poly(lactic-co-glycolic acid) (PLGA) microsphere/poly(vinyl alcohol) (PVA) hydrogel composites were investigated for dexamethasone delivery. A release rate of 25 to 40% over one month, following a zero order profile, was achieved by preferential adsorption of surface active polyacids (poly(acrylic acid), Nafion and HAs) on the hydrogel dispersed microspheres. Environmental scanning electron microscopy investigation on the degradation mechanism of the microspheres pointed towards their slow homogeneous degradation in the PVA hydrogels that was significantly surface-accelerated in the presence of polyacids. The physico

  8. Using semipermeable membrane devices (SPMDs) to assess the toxicity and teratogenicity of aquatic amphibian habitats

    USGS Publications Warehouse

    Bridges, C.M.; Little, E.E.

    2003-01-01

    Environmental contamination has been suspected of being partially responsible for recent declines in amphibian populations. It is often not feasible to identify all of the compounds in an environment, nor the concentrations in which they are present. SPMDs are passive sampling devices that uptake lipophilic compounds from the environment in a manner similar to aquatic organisms. The extracts from the SPMDs, therefore, contain a composite sample of the compounds that are present in the environment. In this paper, we outline the methods from studies in which we have used extracts from SPMDs in toxicity tests on amphibian larvae. Using SPMD extracts makes it possible to establish potential links between amphibian deformities and declines and environmental contamination by lipophilic compounds.

  9. Comparing polychlorinated biphenyl concentrations and patterns in the Saginaw River using sediment, caged fish, and semipermeable membrane devices

    USGS Publications Warehouse

    Echols, K.R.; Gale, R.W.; Schwartz, T.R.; Huckins, J.N.; Williams, L.L.; Meadows, J.C.; Morse, D.; Petty, J.D.; Orazio, C.E.; Tillitt, D.E.

    2000-01-01

    Three techniques of assessing bioavailable polychlorinated biphenyls (PCBs) in the Saginaw River, MI, were compared: sediments, caged fish, and semipermeable membrane devices (SPMDs). SPMDs and caged fish were placed in the river for 28 days at five sites where sediments were also sampled. The samples were analyzed for PCB congeners to determine concentrations and patterns. Total PCB concentrations ranged from 33 to 280 ng/g (dry weight) in sediments, 46 to 290 ng/g (wet weight) in caged fish, and 77 to 790 ng/g in SPMDs. Previously reported rates of PCB accumulation by SPMDs were used to estimate aqueous concentrations from the PCB concentrations detected in the SPMDs. Sediment-water partition coefficients were used to estimate aqueous PCB concentrations from sediment. Steady-state bioconcentration factors and depuration rate constants were used to estimate dissolved PCB concentrations from caged channel catfish. Relative PCB patterns from the SPMDs, caged fish, and sediment were compared using principal components analysis. SPMD and sediment samples provide complementary information. Sediments reflect long-term accumulation and weathering, while SPMDs integrate water concentrations only during the sampling period. Because of higher water solubilities of lower-chlorinated PCBs these predominate in the SPMDs as compared to in the fish and sediments. Contaminant profile differences between caged fish and SPMDs are likely due to metabolism and depuration of certain PCB congeners by fish.Three techniques of assessing bioavailable polychlorinated biphenyls (PCBs) in the Saginaw River, Ml, were compared: sediments, caged fish, and semipermeable membrane devices (SPMDs). SPMDs and caged fish were placed in the river for 28 days at five sites where sediments were also sampled. The samples were analyzed for PCB congeners to determine concentrations and patterns. Total PCB concentrations ranged from 33 to 280 ng/g (dry weight) in sediments, 46 to 290 ng/g (wet weight) in

  10. Comparison of organic contaminant accumulation by semipermeable membrane devices (SPMDs) and the caged mussel species Mytilus edulis

    SciTech Connect

    Hofelt, C.; Shea, D.

    1995-12-31

    The accumulation of anthropogenic contaminants by sentinel species such as the blue mussel, Mytilus edulis, is common in many monitoring programs such as the National Status and Trends Mussel Watch Program. Bivalves are used because they are filter-feeding organisms with a high lipid content and therefore accumulate pollutants readily, and they do not appear to metabolize contaminants to a large extent. There are difficulties associated with this approach however, such as mortality, changing lipid mass and respiration rates, and interspecies differences; therefore the use of a non-living substrate may be more practical. The semipermeable membrane device (SPMD) consists of a length of thin-walled polyethylene tubing with a film of high molecular weight neutral lipid (triolein) sealed inside. The SPMD, when suspended in the water column, will concentrate lipophilic organic contaminants from the surrounding environment. The authors deployed SPMDs and caged Mytilus edulis side-by-side at five sites near New Bedford Harbor, MA; an area highly contaminated with polychlorinated biphenyls (PCBs). A good correlation was observed between the SPMDs and the caged blue mussels, with R{sup 2} ranging from 0.57 to 0.85 (N = 16) for chlorinated pesticides and from 0.81 to 0.96 (N = 20) for PCBs. Bioconcentration factors (BCF) based on water column concentrations were also calculated and a good correlation was obtained between the SPMD BCFs and corresponding octanol-water partition coefficients. Unlike previous investigations, the authors found good agreement even with the highest chlorinated PCBs suggesting that there was no steric hindrance of uptake through the SPMD membrane.

  11. Estimation of uptake rate constants for PCB congeners accumulated by semipermeable membrane devices and brown treat (Salmo trutta)

    USGS Publications Warehouse

    Meadows, J.C.; Echols, K.R.; Huckins, J.N.; Borsuk, F.A.; Carline, R.F.; Tillitt, D.E.

    1998-01-01

    The triolein-filled semipermeable membrane device (SPMD) is a simple and effective method of assessing the presence of waterborne hydrophobic chemicals. Uptake rate constants for individual chemicals are needed to accurately relate the amounts of chemicals accumulated by the SPMD to dissolved water concentrations. Brown trout and SPMDs were exposed to PCB- contaminated groundwater in a spring for 28 days to calculate and compare uptake rates of specific PCB congeners by the two matrixes. Total PCB congener concentrations in water samples from the spring were assessed and corrected for estimated total organic carbon (TOC) sorption to estimate total dissolved concentrations. Whole and dissolved concentrations averaged 4.9 and 3.7 ??g/L, respectively, during the exposure. Total concentrations of PCBs in fish rose from 0.06 to 118.3 ??g/g during the 28-day exposure, while concentrations in the SPMD rose from 0.03 to 203.4 ??g/ g. Uptake rate constants (k1) estimated for SPMDs and brown trout were very similar, with k1 values for SPMDs ranging from one to two times those of the fish. The pattern of congener uptake by the fish and SPMDs was also similar. The rates of uptake generally increased or decreased with increasing K(ow), depending on the assumption of presence or absence of TOC.The triolein-filled semipermeable membrane device (SPMD) is a simple and effective method of assessing the presence of waterborne hydrophobic chemicals. Uptake rate constants for individual chemicals are needed to accurately relate the amounts of chemicals accumulated by the SPMB to dissolved water concentrations. Brown trout and SPMDs were exposed to PCB-contaminated groundwater in a spring for 28 days to calculate and compare uptake rates of specific PCB congeners by the two matrixes. Total PCB congener concentrations in water samples from the spring were assessed and corrected for estimated total organic carbon (TOC) sorption to estimate total dissolved concentrations. Whole and

  12. Caged mussels and semipermeable membrane devices as indicators of organic contaminant uptake in Dorchester and Duxbury Bays, Massachusetts

    SciTech Connect

    Peven, C.S.; Uhler, A.D.; Querzoli, F.J.

    1996-02-01

    An experiment to measure organic contaminant depuration by the blue mussel (Mytilus edulis) was carried out by transplanting mussels in stainless steel cages from a known contaminated site in Dorchester Bay, Massachusetts to a documented clean site in Duxbury Bay, Massachusetts approximately 30 nmi south of the original collection site. A parallel contaminant uptake experiment was performed in which mussels from Duxbury Bay were collected and deployed in similar cages in Dorchester Bay. The bivalves were collected from each transplant site at set intervals over a period of 95 days to monitor the rates and selectivity of depuration and uptake, respectively, of polynuclear atomic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and chlorinated pesticides. In a related study, semipermeable membrane devices (SPMD: polyethylene bags) containing the lipid material triolein were deployed in Dorchester Bay and collected at the same frequency as the caged mussels to evaluate their effectiveness as models for estimating bioconcentration of target organic contaminants. At the Duxbury site, results suggest that the caged mussels depurated contaminants within 68 days to levels found in native animals at the site. At the Dorchester site, bivalves concentrated the contaminants to a level similar to the native M. edulis. PCB and DDT uptake rates were found to be similar between caged mussels and SPMDs; PAH uptake by the SPMDs was initially lower than by transplanted bivalves. PCB and PAH assemblages were noticeably different between bivalves and SPMDs deployed at the same site.

  13. Darcy Permeability of Hollow Fiber Membrane Bundles Made from Membrana Polymethylpentene Fibers Used in Respiratory Assist Devices.

    PubMed

    Madhani, Shalv P; D'Aloiso, Brandon D; Frankowski, Brian; Federspiel, William J

    2016-01-01

    Hollow fiber membranes (HFMs) are used in blood oxygenators for cardiopulmonary bypass or in next generation artificial lungs. Flow analyses of these devices is typically done using computational fluid dynamics (CFD) modeling HFM bundles as porous media, using a Darcy permeability coefficient estimated from the Blake-Kozeny (BK) equation to account for viscous drag from fibers. We recently published how well this approach can predict Darcy permeability for fiber bundles made from polypropylene HFMs, showing the prediction can be significantly improved using an experimentally derived correlation between the BK constant (A) and bundle porosity (ε). In this study, we assessed how well our correlation for A worked for predicting the Darcy permeability of fiber bundles made from Membrana polymethylpentene (PMP) HFMs, which are increasingly being used clinically. Swatches in the porosity range of 0.4 to 0.8 were assessed in which sheets of fiber were stacked in parallel, perpendicular, and angled configurations. Our previously published correlation predicted Darcy within ±8%. A new correlation based on current and past measured permeability was determined: A = 497ε - 103; using this correlation measured Darcy permeability was within ±6%. This correlation varied from 8% to -3.5% of our prior correlation over the tested porosity range. PMID:26809086

  14. Assessment of the usefulness of semipermeable membrane devices for long-term watershed monitoring in an urban slough system

    USGS Publications Warehouse

    McCarthy, K.

    2006-01-01

    Semipermeable membrane devices (SPMDs) were deployed at eight sites within the Buffalo Slough, near Portland, Oregon, to (1) measure the spatial and seasonal distribution of dissolved polycyclic aromatic hydrocarbon (PAH) and organochlorine (OC) compounds in the slough, (2) assess the usefulness of SPMDs as a tool for investigating and monitoring hydrophobic compounds throughout the Columbia Slough system, and (3) evaluate the utility of SPMDs as a tool for measuring the long-term effects of watershed improvement activities. Data from the SPMDs revealed clear spatial and seasonal differences in water quality within the slough and indicate that for hydrophobic compounds, this time-integrated passive-sampling technique is a useful tool for long-term watershed monitoring. In addition, the data suggest that a spiking rate of 2-5 ??g/SPMD of permeability/performance reference compounds, including at least one compound that is not susceptible to photodegradation, may be optimum for the conditions encountered here. ?? Springer Science + Business Media, Inc. 2006.

  15. Numerical study of a novel micro-diaphragm flow channel with piezoelectric device for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ma, H. K.; Huang, S. H.; Chen, B. R.; Cheng, L. W.

    Previous studies have shown that the amplitude of the vibration of a piezoelectric (PZT) device produces an oscillating flow that changes the chamber volume along with a curvature variation of the diaphragm. In this study, an actuating micro-diaphragm with piezoelectric effects is utilized as an air-flow channel in proton exchange membrane fuel cell (PEMFC) systems, called PZT-PEMFC. This newly designed gas pump, with a piezoelectric actuation structure, can feed air into the system of an air-breathing PEMFC. When the actuator moves outward to increase the cathode channel volume, the air is sucked into the chamber; moving inward decreases the channel's volume and thereby compresses air into the catalyst layer and enhancing the chemical reaction. The air-standard PZT-PEMFC cycle is proposed to describe an air-breathing PZT-PEMFC. A novel design for PZT-PEMFCs has been proposed and a three-dimensional, transitional model has been successfully built to account for its major phenomena and performance. Moreover, at high frequencies, PZT actuation leads to a more stable current output, more drained water, higher sucked air, higher hydrogen consumption, and also overcomes concentration losses.

  16. Analysis of NAD(P)+/NAD(P)H cofactors by imprinted polymer membranes associated with ion-sensitive field-effect transistor devices and Au-quartz crystals.

    PubMed

    Pogorelova, Svetlana P; Zayats, Maya; Bourenko, Tatyana; Kharitonov, Andrei B; Lioubashevski, Oleg; Katz, Eugenii; Willner, Itamar

    2003-02-01

    Specific recognition sites for the NAD(P)+ and NAD(P)H cofactors are imprinted in a cross-linked acrylamide-acrylamidophenylboronic acid copolymer membrane. The imprinted membranes, associated with pH-sensitive field-effect transistors (ISFETs) or Au-quartz piezoelectric crystals, enable the potentiometric or microgravimetric analysis of the oxidized NAD(P)+ cofactors and the reduced NAD(P)H cofactors, respectively. The NAD+- and NADP+-imprinted membranes associated with the ISFET allow the analysis of NAD+ and NADP+ with sensitivities that correspond to 15.0 and 18.0 mVdecade(-1) and detection limits of 4 x 10(-7) and 2 x 10(-7) M, respectively. The NADH- and NADPH-imprinted membranes associated with the ISFET device enable the analysis of NADH and NADPH with sensitivities that correspond to 24.2 and 21.8 mV x decade(-1) and lower detection limits that are 1 x 10(-7) and 2 x 10(-7) M, respectively. The ISFET devices functionalized with the NADH and NADPH membranes are employed in the analysis of the biocatalyzed oxidation of lactic acid and ethanol in the presence of lactate dehydrogenase and alcohol dehydrogenase, respectively. PMID:12585477

  17. Simple Host−Guest Chemistry To Modulate the Process of Concentration and Crystallization of Membrane Proteins by Detergent Capture in a Microfluidic Device

    SciTech Connect

    Li, Liang; Nachtergaele, Sigrid; Seddon, Annela M.; Tereshko, Valentina; Ponomarenko, Nina; Ismagilov, Rustem F.

    2009-01-15

    This paper utilizes cyclodextrin-based host-guest chemistry in a microfluidic device to modulate the crystallization of membrane proteins and the process of concentration of membrane protein samples. Methyl-{beta}-cyclodextrin (MBCD) can efficiently capture a wide variety of detergents commonly used for the stabilization of membrane proteins by sequestering detergent monomers. Reaction Center (RC) from Blastochloris viridis was used here as a model system. In the process of concentrating membrane protein samples, MBCD was shown to break up free detergent micelles and prevent them from being concentrated. The addition of an optimal amount of MBCD to the RC sample captured loosely bound detergent from the protein-detergent complex and improved sample homogeneity, as characterized by dynamic light scattering. Using plug-based microfluidics, RC crystals were grown in the presence of MBCD, giving a different morphology and space group than crystals grown without MBCD. The crystal structure of RC crystallized in the presence of MBCD was consistent with the changes in packing and crystal contacts hypothesized for removal of loosely bound detergent. The incorporation of MBCD into a plug-based microfluidic crystallization method allows efficient use of limited membrane protein sample by reducing the amount of protein required and combining sparse matrix screening and optimization in one experiment. The use of MBCD for detergent capture can be expanded to develop cyclodextrin-derived molecules for fine-tuned detergent capture and thus modulate membrane protein crystallization in an even more controllable way.

  18. Light-addressed electrodeposition of enzyme-entrapped chitosan membranes for multiplexed enzyme-based bioassays using a digital micromirror device.

    PubMed

    Huang, Shih-Hao; Wei, Lu-Shiuan; Chu, Hsiao-Tzu; Jiang, Yeu-Long

    2013-01-01

    This paper describes a light-addressed electrolytic system used to perform an electrodeposition of enzyme-entrapped chitosan membranes for multiplexed enzyme-based bioassays using a digital micromirror device (DMD). In this system, a patterned light illumination is projected onto a photoconductive substrate serving as a photo-cathode to electrolytically produce hydroxide ions, which leads to an increased pH gradient. The high pH generated at the cathode can cause a local gelation of chitosan through sol-gel transition. By controlling the illumination pattern on the DMD, a light-addressed electrodeposition of chitosan membranes with different shapes and sizes, as well as multiplexed micropatterning, was performed. The effect of the illumination time of the light pattern on the dimensional resolution of chitosan membrane formation was examined experimentally. Moreover, multiplexed enzyme-based bioassay of enzyme-entrapped chitosan membranes was also successfully demonstrated through the electrodeposition of the chitosan membranes with various shapes/sizes and entrapping different enzymes. As a model experiment, glucose and ethanol were simultaneously detected in a single detection chamber without cross-talk using shape-coded chitosan membranes entrapped with glucose oxidase (GOX), peroxidase (POD), and Amplex Red (AmR) or alcohol oxidase (AOX), POD, and AmR by using same fluorescence indicator (AmR). PMID:23959236

  19. Overview and comparison of lipid-containing semipermeable membrane devices and oysters (Crassostrea gigas) for assessing organic chemical exposure

    USGS Publications Warehouse

    Huckins, J.N.; Prest, H.F.; Petty, J.D.; Lebo, J.A.; Hodgins, M.M.; Clark, R.C.; Alvarez, D.A.; Gala, W.R.; Steen, A.; Gale, R.; Ingersoll, C.G.

    2004-01-01

    We performed 20-d, flow-through exposures of lipid-containing semipermeable membrane devices (SPMDs) and Pacific oysters (Crassostrea gigas) to three concentrations (nominally 10, 100, and 250 ng/L) of a diverse mixture of polycyclic aromatic hydrocarbons (PAHs). Exposure water was seawater free of particulates larger than 0.1 ??m. The results of these controlled laboratory studies demonstrated that SPMDs and oysters concentrate the same chemicals but that the relative amounts accumulated are different. For oysters, the 20-d mean (across treatments) concentration factors (CFs) of test compounds with log Kow ??? 4.8 were much lower (4.0- to 20-fold lower) than those of the same compounds in SPMDs. In contrast, the 20-d CFs of PAHs with log K ow ??? 5.6 in oysters from the low-level treatment were higher than the corresponding CFs for SPMDs. The CFs of these compounds in oysters from the low-level treatment ranged from approximately 3.0- to 13-fold higher than those in oysters from the high-level treatment. This physiologically mediated difference in oyster CFs appears to be linked to active feeding in the low-level treatment and to apparent toxicity-induced cessation of feeding (i.e., valve closure) in the high-level treatment. Because CFs for these compounds in oysters were not independent of exposure concentrations, it follows that tissue levels were not proportional to exposure concentration. However, both sampling approaches have advantages and disadvantages, and the appropriateness of their use depends on the goals of a given study.

  20. How useful are the "other" semipermeable membrane devices (SPMDs); the mini-unit (15.2 cm long)?

    PubMed

    Goodbred, Steven L; Bryant, Wade L; Rosen, Michael R; Alvarez, David; Spencer, Terri

    2009-06-15

    Mini (15.2 cm) semipermeable membrane devices (SPMDs) were used successfully in 169 streams from six metropolitan areas of the US to sequester hydrophobic organic compounds (HOCs) that are indicative of urbanization. A microscale assay the P450RGS, which responds to compounds that bind to the aryl hydrocarbon receptor (AhR), and the Fluoroscan, a chemical screen for polycyclic aromatic hydrocarbons (PAHs), were performed on each mini SPMD extract. Results show both tests were sensitive enough to respond in streams with low urbanization and responded exponentially in a predictable way to a gradient of urbanization. Mini SPMDs had sufficient sampling rates to detect HOCs using gas chromatography with mass spectrometric detection (GC/MS) in streams with low levels of urbanization. The total number of HOCs in streams had a linear response to a gradient of urbanization, where 73 of 140 targeted compounds were detected. A diverse group of compounds was found in urban streams including, PAHs, insecticides, herbicides, musk fragrances, waste water treatment compounds and flame retardants. Pentachloroanisole (PCA), a breakdown product of pentachlorophenol (wood preservative), was the most ubiquitous HOC, and was detected in 71% of streams. An evaluation of mini SPMD performance showed they can detect concentrations in water below toxicity benchmarks for many HOCs with the exception of 2,3,7,8 tetrachlorodibenzo-p-dioxin. A comparison of mini SPMDs with full sized (91.4 cm) SPMDs showed they have several distinct advantages. The most notable advantages are their low cost, small size, and reduced chance of vandalism. The greatest limitation is the inability to detect compounds at low concentrations (pg/L). Mini SPMDs perform quite well in a wide array of environmental settings and applications and should be considered as an option in environmental studies. PMID:19328522

  1. How useful are the "other" semipermeable membrane devices (SPMDs); the mini-unit (15.2 cm long)?

    USGS Publications Warehouse

    Goodbred, Steven L.; Bryant, Wade L.; Rosen, Michael R.; Alvarez, David; Spencer, Terri

    2009-01-01

    Mini (15.2 cm) semipermeable membrane devices (SPMDs) were used successfully in 169 streams from six metropolitan areas of the US to sequester hydrophobic organic compounds (HOCs) that are indicative of urbanization. A microscale assay the P450RGS, which responds to compounds that bind to the aryl hydrocarbon receptor (AhR), and the Fluoroscan, a chemical screen for polycyclic aromatic hydrocarbons (PAHs), were performed on each mini SPMD extract. Results show both tests were sensitive enough to respond in streams with low urbanization and responded exponentially in a predictable way to a gradient of urbanization. Mini SPMDs had sufficient sampling rates to detect HOCs using gas chromatography with mass spectrometric detection (GC/MS) in streams with low levels of urbanization. The total number of HOCs in streams had a linear response to a gradient of urbanization, where 73 of 140 targeted compounds were detected. A diverse group of compounds was found in urban streams including, PAHs, insecticides, herbicides, musk fragrances, waste water treatment compounds and flame retardants. Pentachloroanisole (PCA), a breakdown product of pentachlorophenol (wood preservative), was the most ubiquitous HOC, and was detected in 71% of streams. An evaluation of mini SPMD performance showed they can detect concentrations in water below toxicity benchmarks for many HOCs with the exception of 2,3,7,8 tetrachlorodibenzo-p-dioxin. A comparison of mini SPMDs with full sized (91.4 cm) SPMDs showed they have several distinct advantages. The most notable advantages are their low cost, small size, and reduced chance of vandalism. The greatest limitation is the inability to detect compounds at low concentrations (pg/L). Mini SPMDs perform quite well in a wide array of environmental settings and applications and should be considered as an option in environmental studies.

  2. Field-based evaluation of semipermeable membrane devices (SPMDs) as passive air samplers of polyaromatic hydrocarbons (PAHs)

    USGS Publications Warehouse

    Bartkow, M.E.; Huckins, J.N.; Muller, J.F.

    2004-01-01

    Semipermeable membrane devices (SPMDs) have been used as passive air samplers of semivolatile organic compounds in a range of studies. However, due to a lack of calibration data for polyaromatic hydrocarbons (PAHs), SPMD data have not been used to estimate air concentrations of target PAHs. In this study, SPMDs were deployed for 32 days at two sites in a major metropolitan area in Australia. High-volume active sampling systems (HiVol) were co-deployed at both sites. Using the HiVol air concentration data from one site, SPMD sampling rates were measured for 12 US EPA Priority Pollutant PAHs and then these values were used to determine air concentrations at the second site from SPMD concentrations. Air concentrations were also measured at the second site with co-deployed HiVols to validate the SPMD results. PAHs mostly associated with the vapour phase (Fluorene to Pyrene) dominated both the HiVol and passive air samples. Reproducibility between replicate passive samplers was satisfactory (CV<20%) for the majority of compounds. Sampling rates ranged between 0.6 and 6.1 m3 d-1. SPMD-based air concentrations were calculated at the second site for each compound using these sampling rates and the differences between SPMD-derived air concentrations and those measured using a HiVol were, on average, within a factor of 1.5. The dominant processes for the uptake of PAHs by SPMDs were also assessed. Using the SPMD method described herein, estimates of particulate sorbed airborne PAHs with five rings or greater were within 1.8-fold of HiVol measured values. ?? 2004 Elsevier Ltd. All rights reserved.

  3. Field-based evaluation of semipermeable membrane devices (SPMDs) as passive air samplers of polyaromatic hydrocarbons (PAHs)

    NASA Astrophysics Data System (ADS)

    Bartkow, Michael E.; Huckins, James N.; Müller, Jochen F.

    2004-11-01

    Semipermeable membrane devices (SPMDs) have been used as passive air samplers of semivolatile organic compounds in a range of studies. However, due to a lack of calibration data for polyaromatic hydrocarbons (PAHs), SPMD data have not been used to estimate air concentrations of target PAHs. In this study, SPMDs were deployed for 32 days at two sites in a major metropolitan area in Australia. High-volume active sampling systems (HiVol) were co-deployed at both sites. Using the HiVol air concentration data from one site, SPMD sampling rates were measured for 12 US EPA Priority Pollutant PAHs and then these values were used to determine air concentrations at the second site from SPMD concentrations. Air concentrations were also measured at the second site with co-deployed HiVols to validate the SPMD results. PAHs mostly associated with the vapour phase (Fluorene to Pyrene) dominated both the HiVol and passive air samples. Reproducibility between replicate passive samplers was satisfactory (CV<20%) for the majority of compounds. Sampling rates ranged between 0.6 and 6.1 m3 d-1. SPMD-based air concentrations were calculated at the second site for each compound using these sampling rates and the differences between SPMD-derived air concentrations and those measured using a HiVol were, on average, within a factor of 1.5. The dominant processes for the uptake of PAHs by SPMDs were also assessed. Using the SPMD method described herein, estimates of particulate sorbed airborne PAHs with five rings or greater were within 1.8-fold of HiVol measured values.

  4. Spontaneous structuration in coacervate-based protocells by polyoxometalate-mediated membrane assembly.

    PubMed

    Williams, David S; Patil, Avinash J; Mann, Stephen

    2014-05-14

    Molecularly crowded, polyelectrolyte/ribonucleotide-enriched membrane-free coacervate droplets are transformed into membrane-bounded sub-divided vesicles by using a polyoxometalate-mediated surface-templating procedure. The coacervate to vesicle transition results in reconstruction of the coacervate micro-droplets into novel three-tiered micro-compartments comprising a semi-permeable negatively charged polyoxometalate/polyelectrolyte outer membrane, a sub-membrane coacervate shell, and an internal aqueous lumen. We demonstrate that organic dyes, ssDNA, magnetic nanoparticles and enzymes can be concentrated into the interior of the micro-compartments by sequestration into the coacervate micro-droplets prior to vesicle formation. The vesicle-encapsulated proteins are inaccessible to proteases in the external medium, and can be exploited for the spatial localization and coupling of two-enzyme cascade reactions within single or between multiple populations of hybrid vesicles dispersed in aqueous media. PMID:24515342

  5. Magnetic Membrane System

    DOEpatents

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

    2004-12-30

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

  6. Surface Characterization of Asymmetric Bi-Soft Segment Poly(ester urethane urea) Membranes for Blood-Oxygenation Medical Devices

    PubMed Central

    Faria, Mónica; Geraldes, Vítor; de Pinho, Maria Norberta

    2012-01-01

    Asymmetric bi-soft segment poly(ester urethane urea) (PEUU) membranes containing polycaprolactone (PCL) as a second soft segment are synthesized with PCL-diol ranging from 0% to 15% (w/w). Bulk and surface characteristics of the PEUU membranes were investigated by scanning electron microscopy (SEM), static water contact angles, and surface streaming potentials and were correlated to hemocompatibility properties, namely, hemolysis and thrombosis degrees. SEM analysis reveals PEUU membranes with asymmetric cross-sections and top dense surfaces with distinct morphologies. The increase in PCL-diol content yields PEUU membranes with blood-contacting surfaces that are smoother, more hydrophilic, and with higher maximum zeta potentials. The results obtained in this work give no evidence of a correlation between hydrophilicity/zeta potentials and the hemolysis/thrombosis degree of blood-contacting surfaces of the PEUU membranes. In contrast, other hemocompatibility aspects reveal that the more hydrophilic membranes are associated with lower platelet deposition and inhibition of extreme states of platelet activation. PMID:22164163

  7. [Evaluation of non-invasive hemoglobin measurements using the Masimo Rainbow Radical-7® device in a patient with extracorporeal membrane oxygenation].

    PubMed

    Moreno, I; Artieda, O; Vicente, R; Zarragoikoetxea, I; Vicente, J L; Barberá, M

    2014-01-01

    Circulatory assist devices such as extracorporeal membrane oxygenation are indicated in cases of cardiogenic shock refractory to optimal conventional treatment. Bleeding is a serious complication of such systems, mainly due to coagulation disorders caused by continuous administration of heparin, as well as platelet dysfunction. Serial coagulation and hemoglobin (Hb) measurements are essential. Hb measurements can be performed through repeated arterial blood gasometry, and more recently with a new spectrophotometric sensor, Masimo Rainbow Radical-7® device, which gives Hb values continuously and non-invasively. We report a case of a patient undergoing cardiac surgery who required extracorporeal membrane oxygenation for severe cardiogenic shock immediately after surgery. We compare the correlation and the level of agreement with Hb levels measured by 2 existing systems in clinical practice. Our results indicate that the Masimo® spectrophotometric monitor showed statistically comparable Hb values, in the correlation (r=.85; P<.01) and in agreement with those obtained by serial blood gas analyzer, ABL800 FLEX® (wavelength). In view of these results we consider the Masimo® device as a valid alternative for the continuous follow-up of the Hb and control of bleeding in these patients. PMID:24370278

  8. Water-quality data from semipermeable-membrane devices and polar organic chemical integrative samplers deployed in the McKenzie River basin, Oregon

    USGS Publications Warehouse

    McCarthy, Kathleen A.; Alvarez, David A.

    2012-01-01

    Two types of passive samplers—the semipermeable membrane device (SPMD) and the polar organic chemical integrative sampler (POCIS)—are being used to collect data from the McKenzie River, Oregon. The McKenzie River is the source of drinking water for the City of Eugene, Oregon, and passive-sampler data are part of an ongoing monitoring effort designed to help understand and protect the drinking water source. Data from the passive samplers are reported here. This data report is dynamic and will be appended with additional data as they become available.

  9. Concerted sampling of water for trace organic contaminants by bivalves and semipermeable membrane devices in south San Francisco Bay and Elkhorn Slough

    SciTech Connect

    Hodgins, M.M.; Jacobson, L.A.; Prest, H.F.

    1995-12-31

    Bivalves have been widely applied as biomonitors in detecting organic contaminants in aquatic environments. Recently semipermeable membrane devices (SPMDS) have been shown to be effective pre-concentrators of trace levels of organic compounds in water and air. This study compares accumulation of trace organic compounds in oysters (Crassotrea gigas) and mussels (Mytilus califorianus) to those in SPMDs in south San Francisco Bay and Elkhorn Slough. The authors report concentration levels and trends in the profiles for organochlorine pesticides, polychlorinated biphenyls and polyaromatic hydrocarbons in SPMDs and bivalves from a series of locations in both areas.

  10. In-line sample concentration by evaporation through porous hollow fibers and micromachined membranes embedded in microfluidic devices.

    PubMed

    Zhang, Hainan; Tiggelaar, Roald M; Schlautmann, Stefan; Bart, Jacob; Gardeniers, Han

    2016-02-01

    Two types of microfluidic systems, a porous hollow fiber and a thin supported membrane with an array of micromachined holes, are investigated for concentrating mass-limited analyte samples. Water evaporation is driven by the partial pressure difference across the hydrophobic membrane, induced by dry sweeping gas on the permeate side. An analytical model permitting clarification of the contribution of design and process parameters on acquisition of concentrated solution and prediction of achievable concentration factors is presented. Concentrating an exemplary solution utilizing the two systems has been studied at different experimental conditions to validate the model. The results show that the hollow fiber gives controllable concentration factors of more than 10. For the micromachined membrane concentrator concentration factors of 6-8 were achieved, at much lower flow rates than predicted by the model. Because of the asymptotic dependence of concentration factor on flow rate, accurate control of the liquid feed is extremely critical in the flow rate range where high concentration factors are obtained, and the smallest variations in liquid flow rate may easily lead to supersaturation and deposition of solutes in the pores. This changes membrane porosity in an unpredictable way and limits the maximum attainable concentration factor. PMID:26331575

  11. Induced- and alternating-current electro-osmotic control of the diffusion layer growth in a microchannel-membrane interface device

    NASA Astrophysics Data System (ADS)

    Park, Sinwook; Yossifon, Gilad

    2014-11-01

    The passage of an electric current through an ionic permselective medium under an applied electric field is characterized by the formation of ionic concentration gradients, which result in regions of depleted and enriched ionic concentration at opposite ends of the medium. Induced-current electro-osmosis (ICEO) and alternating-current-electro-osmosis (ACEO) are shown to control the growth of the diffusion layer (DL) which, in turn, controls the diffusion limited ion transport through the microchannel-membrane system. We fabricated and tested devices made of a Nafion membrane connecting two opposite PDMS microchannels. An interdigitated electrode array was embedded within the microchannel with various distances from the microchannel-membrane interface. The induced ICEO (floating electrodes) / ACEO (active electrodes) vortices formed at the electrode array stir the fluid and thereby suppress the growth of the DL. The intensity of the ACEO vortices is controlled by either varying the voltage amplitude or the frequency, each having its own unique effect. Enhancement of the limiting current by on-demand control of the diffusion length is of importance in on-chip electro-dialysis, desalination and preconcentration of analytes.

  12. North American neonatal extracorporeal membrane oxygenation (ECMO) devices and team roles: 2008 survey results of Extracorporeal Life Support Organization (ELSO) centers.

    PubMed

    Lawson, D Scott; Lawson, Andrea F; Walczak, Rich; McRobb, Craig; McDermott, Patty; Shearer, Ian R; Lodge, Andrew; Jaggers, James

    2008-09-01

    In early 2008, surveys of active extracorporeal membrane oxygenation (ECMO) centers in North America were conducted by electronic mail regarding neonatal ECMO equipment and professional staff. Eighty of 103 (78%) North American ECMO centers listed in the Extracorporeal Life Support Organization directory as neonatal centers responded to the survey. Of the responding centers, 82.5% routinely used roller pumps for neonatal ECMO, and the remaining 17.5% used centrifugal pumps. Silicone membrane oxygenators were used by 67% of the respondents, whereas 19% used micro-porous hollow fiber oxygenators, and 14% used polymethylpentene hollow fiber oxygenators. Of the silicone membrane oxygenator users, 86% used the Medtronic Ecmotherm heat exchanger, 10% used the Gish HE-4 heat exchanger, and 4% used the Terumo Conducer device. Sixty-four percent of the responding centers used some form of in-line blood gas monitoring. Six percent of the centers used a bubble trap in the arterial line, and 5% used an arterial line filter. A bladder was used by 85% of the centers, and 4% of these used a mechanical bladder box for servo regulation; the remaining 96% used pressure servo regulation. An air bubble detector was used by 88% of the responding centers. A surface coating was used by 44% of the centers on all their neonatal ECMO patients. Thirty-one percent of the centers use an activated clotting time of 180-220 seconds. At 54% of the responding centers, perfusionists were involved with the ECMO program, registered nurses were involved at 70% of the centers, and respiratory therapists were involved at 46% of the centers. Compared with a 2002 survey, silicone membrane use is declining, and the use of centrifugal blood pumps and coated ECMO circuits is becoming more apparent. ECMO teams are still multidisciplinary, made up of combinations of registered nurses, respiratory therapists, and perfusionists. PMID:18853828

  13. 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

  14. Molecular assessment of the membrane menaquinones of irradiated micrococcus on disposable medical devices with high performance liquid chromatography (HPLC)

    NASA Astrophysics Data System (ADS)

    Ghojaie, M.

    1993-10-01

    The genus of micrococcus and its main species like; M. Roseus, M. Nishinomiyansis consist of upto 10% of microbial contamination of disposable medical devices. Chemical alteration of Menuquinones Mainly [MK-7-(H2), MK-8(H2),…] from some Irradiated species of the micrococcus at different doses (500 Gy to 25 kGy; the sterilization dose) are quantitatively evaluated by HPLC.

  15. Offshore Membrane Enclosures for Growing Algae (OMEGA: A System for Biofuel Production, Wastewater Treatment, and CO2 Sequestration

    NASA Technical Reports Server (NTRS)

    Trent, Jonathan; Embaye, Tsegereda; Buckwalter, Patrick; Richardson, Tra-My; Kagawa, Hiromi; Reinsch, Sigrid; Martis, Mary

    2010-01-01

    We are developing Offshore Membrane Enclosures for Growing Algae (OMEGA). OMEGAs are closed photo-bioreactors constructed of flexible, inexpensive, and durable plastic with small sections of semi-permeable membranes for gas exchange and forward osmosis (FO). Each OMEGA modules is filled with municipal wastewater and provided with CO2 from coastal CO2 sources. The OMEGA modules float just below the surface, and the surrounding seawater provides structural support, temperature control, and mixing for the freshwater algae cultures inside. The salinit7 gradient from inside to outside drives forward osmosis through the patches of FO membranes. This concentrates nutrients in the wastewater, which enhances algal growth, and slowly dewaters the algae, which facilitates harvesting. Thy concentrated algal biomass is harvested for producing biofuels and fertilizer. OMEGA system cleans the wastewater released into the surrounding coastal waters and functions as a carbon sequestration system.

  16. Offshore Membrane Enclosure for Growing Algai (Omega) System for Biofuel Production, Wastewater Treatment, and CO2 Sequestration

    NASA Technical Reports Server (NTRS)

    Trent, Jonathan; Embaye, Tsegereda; Buckwalter, Patrick; Richardson, Tra-My; Kagawa, Hiromi; Reinsch, Sigrid

    2010-01-01

    We are developing Offshore Membrane Enclosures for Growing Algae (OMEGA). OMEGAs are closed photo-bioreactors constructed of flexible, inexpensive, and durable plastic with small sections of semi-permeable membranes for gas exchange and forward osmosis (FO). Each OMEGA modules is filled with municipal wastewater and provided with CO2 from coastal CO2 sources. The OMEGA modules float just below the surface, and the surrounding seawater provides structural support, temperature control, and mixing for the freshwater algae cultures inside. The salinity gradient from inside to outside drives forward osmosis through the patches of FO membranes. This concentrates nutrients in the wastewater, which enhances algal growth, and slowly dewaters the algae, which facilitates harvesting. The concentrated algal biomass is harvested for producing biofuels and fertilizer. OMEGA system cleans the wastewater released into the surrounding coastal waters and functions as a carbon sequestration system.

  17. Effect of electrode geometry on field strength in plastic microfluidic devices and application to cell membrane permeabilization

    NASA Astrophysics Data System (ADS)

    Chooljian, Marc; Paredes, Jacobo; Liepmann, Dorian

    2014-11-01

    We have developed a method that allows embedding of electrodes in up to 3 walls of a plastic microfluidic channel. Electric field strength and homogeneity of various electrode geometries is analyzed theoretically and experimentally by evaluating the efficiency of on-chip lysis of cells. Electric field-mediated disruption of membranes is an important tool in diagnostics, basic biology, and synthetic biology due to the ability to permeabilize the cell membrane without changing the chemical composition of the buffer. Typically, fields of the required magnitude are applied to the cell by discharging a capacitor through a mixture of cells in a cuvette, resulting in a transient high-voltage pulse. We demonstrate that is possible to substitute a spatially varied DC electric field along a microchannel and to control the timing of the pulses by changing the electrode spacing and the flow rate. Homogeneity of the field with respect to the cross section of the channel is key to achieving critical field strength regardless of the cell's lateral position in the channel. A comparison of 2D versus 3D electrode geometries on the efficiency of electroporation and on side-effects arising due to the electric field (recirculating flows and hydrolysis) is presented.

  18. Occurrence and concentrations of polycyclic aromatic hydrocarbons in semipermeable membrane devices and clams in three urban streams of the Dallas-Fort Worth Metropolitan Area, Texas

    USGS Publications Warehouse

    Moring, J.B.; Rose, D.R.

    1997-01-01

    Semipermeable membrane devices (SPMDs) and Asiatic clams, Corbicula fluminea (MuLLER), were deployed at stream sites in the Dallas-Fort Worth Metropolitan Area to assess the presence of bioavailable, dissolved polycyclic aromatic hydrocarbons (PAHs). Twenty-four PAHs were detected in SPMDs, 20 of which occurred at all sites. Only three PAHs were detected in the co-deployed clams. Throughout all sites, non-alkylated PAHs were found at greater levels in SPMDs than alkylated forms. Nine of 16 Priority Pollutant PAHs were detected in SPMDs. Estimated concentrations of PAHs in water were generally two to three orders of magnitude less than standard minimum analytical reporting levels; however, for bent (a) anthracene, benzo (a) pyrene, and chrysene, estimated concentrations in water exceeded the U.S. Environmental Protection Agency's human health criteria for these carcinogens in water and aquatic organisms.

  19. Fullerene-assisted electron-beam lithography for pattern improvement and loss reduction in InP membrane waveguide devices.

    PubMed

    Jiao, Yuqing; Pello, Josselin; Mejia, Alonso Millan; Shen, Longfei; Smalbrugge, Barry; Geluk, Erik Jan; Smit, Meint; van der Tol, Jos

    2014-03-15

    In this Letter, we present a method to prepare a mixed electron-beam resist composed of a positive resist (ZEP520A) and C60 fullerene. The addition of C60 to the ZEP resist changes the material properties under electron beam exposure significantly. An improvement in the thermal resistance of the mixed material has been demonstrated by fabricating multimode interference couplers and coupling regions of microring resonators. The fabrication of distributed Bragg reflector structures has shown improvement in terms of pattern definition accuracy with respect to the same structures fabricated with normal ZEP resist. Straight InP membrane waveguides with different lengths have been fabricated using this mixed resist. A decrease of the propagation loss from 6.6 to 3.3  dB/cm has been demonstrated. PMID:24690859

  20. Miniaturized supported liquid membrane device for selective on-line enrichment of basic drugs in plasma combined with capillary zone electrophoresis.

    PubMed

    Pálmarsdóttir, S; Thordarson, E; Edholm, L E; Jönsson, J A; Mathiasson, L

    1997-05-01

    A hollow fiber miniaturized supported liquid membrane (SLM) device for sample preparation is connected on-line with capillary electrophoresis and used for determination of a basic drug, bambuterol, in human plasma. The analyte is extracted from the outside of the hollow fiber (donor) through the liquid membrane (pores of the fiber impregnated with organic solvent) into the acceptor solution in the fiber lumen. The process is driven by differences in pH between the donor and acceptor solution. The whole volume of the acceptor solution can then be injected into the CZE capillary by using the double-stacking procedure for large volume-injection. Very clean extracts of low ionic strength are obtained from the SLM treatment, making this sample pretreatment method compatible with the CZE double-stacking procedure, which in turn makes it possible to inject large volumes of sample onto the separation capillary. Good performance of the whole procedure is demonstrated, and detection limits in the low nanomolar range were obtained in spite of the relatively weak UV absorbance of bambuterol. Extractions through the miniaturized SLM unit can be performed for 5-6 h without regenerating the fiber. The regeneration procedure was tested, and no relevant changes in the performance of the extraction could be found after seven regenerations, allowing the same fiber to be used for a week. PMID:9145027

  1. A review of water recovery by vapour permeation through membranes.

    PubMed

    Bolto, Brian; Hoang, Manh; Xie, Zongli

    2012-02-01

    In vapour permeation the feed is a vapour, not a liquid as in pervaporation. The process employs a polymeric membrane as a semi-permeable barrier between the feed side under high pressure and the permeate side under low pressure. Separation is achieved by the different degrees to which components are dissolved in and diffuse through the membrane, the system working according to a solution-diffusion mechanism. The materials used in the membrane depend upon the types of compounds being separated, so water transport is favoured by hydrophilic material, whether organic or inorganic. The process is used for the dehydration of natural gas and various organic solvents, notably alcohol as biofuel, as well as the removal of water from air and its recovery from waste steam. Waste steam can be found in almost every plant/factory where steam is used. It is frequently contaminated and cannot be reused. Discharging the spent steam to the atmosphere is a serious energy loss and environmental issue. Recycling the steam can significantly improve the overall energy efficiency of an industry, which is responsible for massive CO(2) emissions. Steam separation at high fluxes and temperatures has been accomplished with a composite poly(vinyl alcohol) membrane containing silica nanoparticles, and also, less efficiently, with an inorganic zeolite membrane. PMID:22100055

  2. Assessment of the significance of direct and indirect pollution inputs to a major salmon-producing river using polyethylene membrane devices.

    PubMed

    Moles, Adam; Holland, Larry; Andersson, Ole

    2006-08-01

    Conventional passive sampling devices for monitoring pollution input often prove to be cost-prohibitive when assessing large spatial and temporal scales. The Kenai River, a major salmon-producing river in Alaska (USA), served as the perfect laboratory to test the utility of polyethylene membrane devices for assessing chronic nonpoint-source inputs to a large riverine watershed. Comparison of the relative levels of polycyclic aromatic hydrocarbons (PAHs) at a large number of locations over time allowed us to assess the significance and potential source of these compounds in the river. Concentrations of PAH were greatest near urban areas and peaked during the late winter, when streams flows and dilution were low. Vessel activity and PAH levels peaked in July and were heaviest in the lower 16 km of the river, where fishing activity was concentrated. Nearly one-third of the vessels observed on the river were powered by two-stroke engines, which release a higher proportion of unburned fuel into the water than the cleaner burning four-stroke engines. The low concentrations of hydrocarbons upriver of the boat traffic suggest very little remote delivery of these contaminants to the watershed. Polyethylene strips proved to be an excellent, low-cost tool for determining the PAH patterns in a large watershed. PMID:16916019

  3. Membrane with supported internal passages

    NASA Technical Reports Server (NTRS)

    Gonzalez-Martin, Anuncia (Inventor); Salinas, Carlos E. (Inventor); Cisar, Alan J. (Inventor); Hitchens, G. Duncan (Inventor); Murphy, Oliver J. (Inventor)

    2000-01-01

    The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface comprising permanent tubes preferably placed at the ends of the fluid passages. The invention also provides an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane.

  4. Development of a membrane-less dynamic field gradient focusing device for the separation of low-molecular-weight molecules

    PubMed Central

    Burke, Jeffrey M.; Smith, Colin D.; Ivory, Cornelius F.

    2010-01-01

    Dynamic field gradient focusing uses an electric field gradient generated by controlling the voltage profile of an electrode array to separate and concentrate charged analytes according to their individual electrophoretic mobilities. This study describes a new instrument in which the electrodes have been placed within the separation channel. The major challenge faced with this device is that when applied voltages to the electrodes are larger than the redox potential of water, electrolysis will occur, producing hydrogen ions (H+) plus oxygen gas on the anodes and hydroxide (OH−) plus hydrogen gas on the cathodes. The resulting gas bubbles and pH excursions can cause problems with system performance and reproducibility. An on-column, degassing system that can remove gas bubbles “on-the-fly” is described. In addition, the use of a high capacity, low-conductivity buffer to address the problem of the pH shift that occurs due to the production of H+ on the anodes is illustrated. Finally, the successful separation of three, low-molecular-weight dyes (amaranth, bromophenol blue and methyl red) is described. PMID:20191553

  5. Determination of uptake kinetics (sampling rates) by lipid-containing semipermeable membrane devices (SPMDs) for polycyclic aromatic hydrocarbons (PAHs) in water

    USGS Publications Warehouse

    Huckins, J.N.; Petty, J.D.; Orazio, C.E.; Lebo, J.A.; Clark, R.C.; Gibson, V.L.; Gala, W.R.; Echols, K.R.

    1999-01-01

    The use of lipid-containing semipermeable membrane devices (SPMDs) is becoming commonplace, but very little sampling rate data are available for the estimation of ambient contaminant concentrations from analyte levels in exposed SPMDs. We determined the aqueous sampling rates (R(s)s; expressed as effective volumes of water extracted daily) of the standard (commercially available design) 1-g triolein SPMD for 15 of the priority pollutant (PP) polycyclic aromatic hydrocarbons (PAHs) at multiple temperatures and concentrations. Under the experimental conditions of this study, recovery- corrected R(s) values for PP PAHs ranged from ???1.0 to 8.0 L/d. These values would be expected to be influenced by significant changes (relative to this study) in water temperature, degree of biofouling, and current velocity- turbulence. Included in this paper is a discussion of the effects of temperature and octanol-water partition coefficient (K(ow)); the impacts of biofouling and hydrodynamics are reported separately. Overall, SPMDs responded proportionally to aqueous PAH concentrations; i.e., SPMD R(s) values and SPMD-water concentration factors were independent of aqueous concentrations. Temperature effects (10, 18, and 26 ??C) on Rs values appeared to be complex but were relatively small.The use of lipid-containing semipermeable membrane devices (SPMDs) is becoming commonplace, but very little sampling rate data are available for the estimation of ambient contaminant concentrations from analyte levels in exposed SPMDs. We determined the aqueous sampling rates (Rss; expressed as effective volumes of water extracted daily) of the standard (commercially available design) 1-g triolein SPMD for 15 of the priority pollutant (PP) polycyclic aromatic hydrocarbons (PAHs) at multiple temperatures and concentrations. Under the experimental conditions of this study, recovery-corrected Rs values for PP PAHs ranged from ???1.0 to 8.0 L/d. These values would be expected to be influenced by

  6. Identification of methyl triclosan and halogenated analogues in male common carp (Cyprinus carpio) from Las Vegas Bay and semipermeable membrane devices from Las Vegas Wash, Nevada

    USGS Publications Warehouse

    Leiker, T.J.; Abney, S.R.; Goodbred, S.L.; Rosen, Michael R.

    2009-01-01

    Methyl triclosan and four halogenated analogues have been identified in extracts of individual whole-body male carp (Cyprinus carpio) tissue that were collected from Las Vegas Bay, Nevada, and Semipermeable Membrane Devices (SPMD) that were deployed in Las Vegas Wash, Nevada. Methyl triclosan is believed to be the microbially methylated product of the antibacterial agent triclosan (2, 4, 4'-trichloro-4-hydroxydiphenyl ether, Chemical Abstract Service Registry Number 3380-34-5, Irgasan DP300). The presence of methyl triclosan and four halogenated analogues was confirmed in SPMD extracts by comparing low- and high-resolution mass spectral data and Kovats retention indices of methyl triclosan with commercially obtained triclosan that was derivatized to the methyl ether with ethereal diazomethane. The four halogenated analogues of methyl triclosan detected in both whole-body tissue and SPMD extracts were tentatively identified by high resolution mass spectrometry. Methyl triclosan was detected in all 29 male common carp from Las Vegas Bay with a mean concentration of 596????g kg- 1 wet weight (ww) which is more than an order of magnitude higher than previously reported concentrations in the literature. The halogenated analogs were detected less frequently (21%-76%) and at much lower concentrations (< 51????g kg- 1 ww). None of these compounds were detected in common carp from a Lake Mead reference site in Overton Arm, Nevada.

  7. Accumulation of polycyclic aromatic hydrocarbons in semipermeable membrane devices and caged mussels (Mytilus edulis L.) in relation to water column phase distribution

    SciTech Connect

    Axelman, J.; Naes, K.; Naef, C.; Broman, D.

    1999-11-01

    Semipermeable membrane devices (SPMDs) and blue mussels (Mytilus edulis L.) were deployed at a site contaminated by discharges of polycyclic aromatic hydrocarbons (PAHs) from an aluminium reduction plant, and at a reference site. The accumulation of PAHs in SPMDs versus mussels, along with the ability of the two matrices to predict contaminant concentrations in the ambient environment, were evaluated through concurrent measurements of particulate, dissolved, and colloidal PAHs in the water column. Analysis of the results showed that blue mussels were more efficient at sequestering PAHs than were SPMDs. The PAH profile (i.e,, the relative abundance of individual PAHs) in the two matrices were similar, but differed significantly from the profile in the dissolved phase. Further, back-calculation of the ambient dissolved concentrations from SPMDs indicated systematic overtrapping with increasing hydrophobicity. Calculation of in situ bioconcentration factors (BCFs) for the blue mussels at the smelter site indicated that uptake via particles or from colloids dominated over direct uptake from the dissolved phase, as opposed to the reference site. The in situ BCFs differed markedly from literature values, which implies that the use of mussels to predict ambient concentrations would require that site-specific BCFs be applied.

  8. Guidelines for the use of the semipermeable membrane device (SPMD) and the polar organic chemical integrative sampler (POCIS) in environmental monitoring studies

    USGS Publications Warehouse

    Alvarez, David A.

    2010-01-01

    the semipermeable membrane device (SPMD) and the polar organic chemical integrative sampler (POCIS). The tips given in this document focus on these two samplers but are applicable to most types of passive sampling devices. The information in this guide is heavily weighted towards the sampling of water; however, information specific to the use of SPMDs for air sampling will also be covered.

  9. Investigation of the distribution of organochlorine and polycyclic aromatic hydrocarbon compounds in the Lower Columbia River using semipermeable-membrane devices

    USGS Publications Warehouse

    McCarthy, Kathleen A.; Gale, Robert W.

    1999-01-01

    Organochlorine and polycyclic aromatic hydrocarbon compounds are of concern in the Columbia River Basin because of their adverse effects on fish and wildlife. Because these compounds can have important biological consequences at concentrations well below the detection limits associated with conventional water-sampling techniques, we used semipermeable membrane devices (SPMDs) to sample water, and achieved sub-parts-per-quintillion detection limits. We deployed SPMDs during 1997 low-flow conditions and 1998 high-flow conditions at nine main-stem sites and seven tributary sites, spanning approximately 700 miles of the Columbia River. We also collected streambed sediment from three sites. SPMD extracts and sediments were analyzed for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, organochlorine pesticides and related transformation products, and polycyclic aromatic hydrocarbons. Our data indicate that (1) in the absence of additional sources, mechanisms such as volatilization, dilution, and settling of suspended particles can act to significantly reduce concentrations of contaminants along the river's flow path, (2) elevated concentrations of contaminants in the Portland-Vancouver area are primarily from local rather than upstream sources, (3) elevated concentrations of many compounds tend to be diluted during periods of high discharge, (4) much higher discharge in the main stem considerably dilutes elevated concentrations entering from tributaries, (5) the distribution of hydrophobic organic compounds in streambed sediment is not necessarily indicative of their distribution in the dissolved-phase, and (6) SPMDs can reveal patterns of contaminant occurrence at environmentally relevant concentrations that are undetectable by conventional water-sampling techniques.

  10. Time-integrated, flux-based monitoring using semipermeable membrane devices to estimate the contribution of industrial facilities to regional polychlorinated biphenyl budgets

    SciTech Connect

    McCarthy, J.F.; Southworth, G.R.; Ham, K.D.; Palmer, J.A.

    2000-02-01

    Passive monitoring of polychlorinated biphenyls (PCB) using semipermeable membrane devices (SPMD) was employed to evaluate the contribution of point and nonpoint sources to the flux of PCB in a drainage system encompassing three US Department of Energy (US DOE) industrial and research facilities in eastern Tennessee, USA. Polychlorinated biphenyls concentrations were highest at outfalls containing process waste from the DOE industrial facilities. The significance of these releases was evaluated by calculating the PCB flux (mass per unit time) at different monitoring locations. The flux was calculated from the time-integrated estimates of the aqueous concentrations of PCB and estimates of the volumetric flow rates of discharges and receiving streams during the deployment period. The DOE discharges accounted for most of the flux of PCB entering the Clinch River from the DOE drainage areas, but these sources constituted only 10% of the flux in the Clinch River about the DOE sources. Principal components analysis was helpful in attributing sources of PCB. In a stream receiving multiple inputs of PCB, congener profiles from upstream sources and discrete discharges were consistent with a mixture of those congener profiles in the downstream receiving water. In another stream with a single upstream source of PCB, changes in PCB flux and congener profiles suggested an apparent steady-state distribution between dissolved PCB and PCB adsorbed to organic matter on the streambed. The flux of dissolved PCB along different stream reaches reflected changes in the sediment organic content. Subtle alterations in congener profiles moving downstream suggested preferential desorption of less chlorinated congeners and sorption of more highly chlorinated congeners to sediment. Time-integrated, flux-based monitoring can be useful across a range of spatial scales for evaluating the significance of point and nonpoint contaminant sources and can help identify and prioritize feasible remedial

  11. Comparison of the uptake of polycyclic aromatic hydrocarbons and organochlorine pesticides by semipermeable membrane devices and caged fish (Carassius carassius) in Taihu Lake, China

    USGS Publications Warehouse

    Ke, R.; Xu, Y.; Huang, S.; Wang, Z.; Huckins, J.N.

    2007-01-01

    Uptake of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) by triolein-containing semipermeable membrane devices (SPMDs) and by crucian carp (Carassius carassius) was studied in Taihu Lake, a shallow, freshwater lake in China. Crucian carp and SPMDs were deployed side by side for 32 d. The first-order uptake rate constants of individual PAHs and OCPs for the two matrices were calculated and compared to relate the amounts of chemicals accumulated by the matrices to dissolved water concentrations. On a wet-weight basis, total concentrations of PAHs and OCPs in crucian carp fillets averaged 49.5 and 13.6 ng/g, respectively, after the 32-d exposure, whereas concentrations in whole SPMDs averaged 716.9 and 62.3 ng/g, respectively. The uptake rate constants of PAHs and OCPs by SPMDs averaged seven- and fivefold higher, respectively, than those for crucian carp; however, the patterns of uptake rate constants derived from test chemical concentrations in the crucian carp and SPMDs were similar. Although equilibrium was not reached for some PAHs and OCPs during the 32-d exposure period, a reasonably good correlation between the concentration factors (CFs) and octanol/water partition coefficient (K ow) values of PAHs and OCPs in SPMDs (r = 0.86, p < 0.001) was observed when potential sorption to dissolved organic carbon was taken into account. Similar efforts to correlate the CFs and Kow values of PAHs and OCPs in crucian carp (r = 0.75, p < 0.001) were less successful, likely because of PAH metabolism by finfish. Overall, the present results suggest that SPMDs may serve as a surrogate for contaminant monitoring with fish in freshwater lake environments. ?? 2007 SETAC.

  12. Photosensitized degradation kinetics of trace halogenated contaminants in natural waters using membrane introduction mass spectrometry as an in situ reaction monitor.

    PubMed

    Letourneau, Dane R; Gill, Chris G; Krogh, Erik T

    2015-11-01

    The photochemically mediated dechlorination of polyhalogenated compounds represents a potential decontamination strategy and a relevant environmental process in chemically reducing media. We report the UV irradiation of natural and artificial waters containing natural dissolved organic matter to effect the photo-sensitized degradation of chlorinated organic compounds, including tetrachloromethane, 1,1,1-tricloroethane, perchloroethene, 1,2-dibromo-3-chloropropane and chlorobenzene at trace (ppb) levels in aqueous solution. The degradation kinetics are followed in situ using membrane introduction mass spectrometry. By re-circulating the reaction mixture in a closed loop configuration over a semi-permeable hollow fiber polydimethylsiloxane membrane in a flow cell interface, volatile and semi-volatile compounds are continuously monitored using a quadrupole ion trap mass spectrometer. The time resolved quantitative information provides useful mechanistic insights, including kinetic data. Pseudo first-order rate constants for the degradation of contaminant mixtures in natural waters are reported. PMID:26439106

  13. TOXICOLOGICAL STUDIES IN TROPICAL ECOSYSTEMS: AN ECOTOXICOLOGICAL RISK ASSESSMENT OF PESTICIDE RUNOFF IN SOUTH FLORIDA ESTUARINE ECOSYSTEMS

    EPA Science Inventory

    A multi-year study in the C-111 canal and associated sites in Florida Bay was undertaken in order to determine the potential contaminant risk that exists in South Florida. After examining extensive surface water data, as well as sediment, tissue, and semi-permeable membrane devic...

  14. Designing Mimics of Membrane Active Proteins

    PubMed Central

    Sgolastra, Federica; deRonde, Brittany M.; Sarapas, Joel M.; Som, Abhigyan; Tew, Gregory N.

    2014-01-01

    CONSPECTUS As a semi-permeable barrier that controls the flux of biomolecules in and out the cell, the plasma membrane is critical in cell function and survival. Many proteins interact with the plasma membrane and modulate its physiology. Within this large landscape of membrane-active molecules, researchers have focused significant attention on two specific classes of peptides, antimicrobial peptides (AMPs) and cell penetrating peptides (CPPs) because of their unique properties. In this account, we describe our efforts over the last decade to build and understand synthetic mimics of antimicrobial peptides (SMAMPs). These endeavors represent one specific example of a much larger effort to understand how synthetic molecules interact with and manipulate the plasma membrane. Using both defined molecular weight oligomers and easier to produce, but heterogeneous, polymers, it has been possible to generate scaffolds with biological potency superior to the natural analogs. In one case, a compound has progressed through a phase II clinical trial for pan)staph infections. Modern biophysical assays highlighted the interplay between the synthetic scaffold and lipid composition leading to negative Gaussian curvature, a requirement for both pore formation and endosomal escape. The complexity of this interplay between lipids, bilayer components, and the scaffolds remains to be better resolved, but significant new insight has been provided. It is worthwhile to consider the various aspects of permeation and how these are related to ‘pore formation.’ More recently, our efforts have expanded toward protein transduction domains, or cell penetrating peptide, mimics. The combination of unique molecular scaffolds and guanidinium) rich side chains has produced an array of polymers with robust transduction (and delivery) activity. Being a new area, the fundamental interactions between these new scaffolds and the plasma membrane are just beginning to be understood. Negative Gaussian

  15. Evaluation of the measurement of Cu(II) bioavailability in complex aqueous media using a hollow-fiber supported liquid membrane device (HFSLM) and two microalgae species (Pseudokirchneriella subcapitata and Scenedesmus acutus).

    PubMed

    Rodríguez-Morales, Erik A; Rodríguez de San Miguel, Eduardo; de Gyves, Josefina

    2015-11-01

    The environmental bioavailability of copper was determined using a hollow-fiber supported liquid membrane (HFSLM) device as a chemical surrogate and two microalgae species (Scenedesmus acutus and Pseudokirchneriella subcapitata). Several experimental conditions were studied: pH, the presence of organic matter, inorganic anions, and concomitant cations. The results indicated a strong relationship between the response given by the HFSLM and the microalgae species with free copper concentrations measured by an ion selective electrode (ISE), in accordance with the free-ion activity model (FIAM). A significant positive correlation was evident when comparing the bioavailability results measured by the HFSLM and the S. acutus microalga species, showing that the synthetic device may emulate biological uptake and, consequently, be used as a chemical test for bioavailability measurements using this alga as a biological reference. PMID:26431807

  16. Kawasaki Disease With Giant Coronary Aneurysms Requiring a Ventricular Assist Device to Separate From Extracorporeal Membrane Oxygenation: Coronary Issues Can Be a Pediatric Problem Too!

    PubMed

    Adler, Adam C; Kodavatiganti, Ramesh

    2016-08-15

    Kawasaki disease, although common in children, may rarely affect the coronary arteries, leading to aneurysm formation and potential for coronary thrombus formation. Extremely rarely, coronary aneurysms from Kawasaki disease can thrombose, resulting in ischemic myocardium. We present a case of a 31-month-old patient requiring a left ventricular assist device after thrombosis of giant coronary aneurysms led to ischemic cardiomyopathy. At the termination of the surgical procedure, we encountered 2 periods of ventricular assist device dropout requiring intervention. With the increase in the number of pediatric patients with assist devices, we review the basic care for a patient requiring emergent surgery. PMID:27310902

  17. Neonatal extracorporeal membrane oxygenation devices, techniques and team roles: 2011 survey results of the United States' Extracorporeal Life Support Organization centers.

    PubMed

    Lawson, Scott; Ellis, Cory; Butler, Katie; McRobb, Craig; Mejak, Brian

    2011-12-01

    In early 2011, surveys of active Extracorporeal Life Support Organization (ELSO) centers within the United States were conducted by electronic mail regarding neonatal Extracorporeal Membrane Oxygenation (ECMO) equipment and professional staff. Seventy-four of 111 (67%) U.S. centers listed in the ELSO directory as neonatal centers responded to the survey. Of the responding centers, 53% routinely used roller pumps for neonatal ECMO, 15% reported using centrifugal pumps and 32% reported using a combination of both. Of the centers using centrifugal pumps, 51% reported that they do not use a compliance bladder in the circuit. The majority (95%) of roller pump users reported using a compliance bladder and 97% reported using Tygon" S-97-E tubing in the raceway of their ECMO circuits. Silicone membrane oxygenators were reportedly used by 25% of the respondents, 5% reported using micro-porous hollow fiber oxygenators (MPHF), 70% reported using polymethylpentene (PMP) hollow fiber oxygenators and 5% reported using a combination of the different types. Some form of in-line blood monitoring was used by 88% of the responding centers and 63% of responding centers reported using a circuit surface coating. Anticoagulation monitoring via the activated clotting time (ACT) was reported by 100% of the reporting centers. The use of extracorporeal cardiopulmonary resuscitation (ECPR) was reported by 53% of the responding centers with 82% of those centers using a crystalloid primed circuit to initiate ECPR. A cooling protocol was used by 77% of the centers which have an ECPR program. When these data are compared with surveys from 2002 and 2008 it shows that the use of silicone membrane oxygenators continues to decline, the use of centrifugal pumps continues to increase and ECMO personnel continues to be comprised of multidisciplinary groups of dedicated allied health care professionals. PMID:22416604

  18. Neonatal Extracorporeal Membrane Oxygenation Devices, Techniques and Team Roles: 2011 Survey Results of the United States’ Extracorporeal Life Support Organization Centers

    PubMed Central

    Lawson, Scott; Ellis, Cory; Butler, Katie; McRobb, Craig; Mejak, Brian

    2011-01-01

    Abstract: In early 2011, surveys of active Extracorporeal Life Support Organization (ELSO) centers within the United States were conducted by electronic mail regarding neonatal Extracorporeal Membrane Oxygenation (ECMO) equipment and professional staff. Seventy-four of 111 (67%) U.S. centers listed in the ELSO directory as neonatal centers responded to the survey. Of the responding centers, 53% routinely used roller pumps for neonatal ECMO, 15% reported using centrifugal pumps and 32% reported using a combination of both. Of the centers using centrifugal pumps, 51% reported that they do not use a compliance bladder in the circuit. The majority (95%) of roller pump users reported using a compliance bladder and 97% reported using Tygon® S-97-E tubing in the raceway of their ECMO circuits. Silicone membrane oxygenators were reportedly used by 25% of the respondents, 5% reported using micro-porous hollow fiber oxygenators (MPHF), 70%reported using polymethylpentene (PMP) hollow fiber oxygenators and 5% reported using a combination of the different types. Some form of in-line blood monitoring was used by 88% of the responding centers and 63% of responding centers reported using a circuit surface coating. Anticoagulation monitoring via the activated clotting time (ACT) was reported by 100% of the reporting centers. The use of extracorporeal cardiopulmonary resuscitation (ECPR) was reported by 53% of the responding centers with 82% of those centers using a crystalloid primed circuit to initiate ECPR. A cooling protocol was used by 77% of the centers which have an ECPR program. When these data are compared with surveys from 2002 and 2008 it shows that the use of silicone membrane oxygenators continues to decline, the use of centrifugal pumps continues to increase and ECMO personnel continues to be comprised of multidisciplinary groups of dedicated allied health care professionals. PMID:22416604

  19. Supported membrane nanodevices.

    PubMed

    Anrather, Dorothea; Smetazko, Michaela; Saba, Miriam; Alguel, Yilmaz; Schalkhammer, Thomas

    2004-01-01

    Supported membrane nanodevices are based on natural or artificial ion channels embedded in a lipid membrane deposited on a chip wafer. Membrane conductance is modulated by biorecognitive events, with the use of intrinsic binding sites of the ion channel or via artificial sites fused to the channel protein. Artificial ion gates are constructed by coupling a specific ligand for the analyte near the channel entrance or a site important to triggering channel conformation. The binding event leads to the closure of the ion channel or induces a conformational change of the channel, reducing the ion flux. The signal transduced from the device is the decrease in the ion flux-induced electron current at a silver-silver chloride electrode at ultimate single-molecule sensitivity. Among the natural ion channels, gramicidin A, a transport antibiotic, was found to be most suitable, and thus was used by AMBRI, Australia, to set up prototypes of membrane biochips, using self-association of the dimer. Covalent dimerization-based devices, developed by the Vienna group, make use of the down-regulation of the permanently open membrane-spanning bisgramicidine ion channel. The reactive group at the C-terminus, a hydroxy group, allows precise coupling of the analyte-binding moiety in gramicidin as well as bisgramicidin. The device is set up with bilayer membranes deposited on apertures of a hydrophobic frame structure produced via microlithography, facing an aqueous or hydro-gel micro-environment on both sides, constructing black lipid membranes or patch-clamp devices "on chip." The setup of the device needs gel membrane supports that allow membrane formation and contribute to the stability of the bilayer by exposure of functional groups that promote electrostatic interaction and formation of hydrogen bridges and enable the introduction of covalent spacers and anchors. Photo-cross-linked polyvinylpyrrolidone and polyacrylamide, electropolymerized polydiaminobenzene and coated agarose, as

  20. Minimally invasive implantation of an extracorporeal membrane oxygenation circuit used as a temporary left ventricular assist device: a new concept for bridging to permanent cardiac support.

    PubMed

    Saito, Shunsuke; Fleischer, Bernhard; Maeß, Christoph; Baraki, Hassina; Kutschka, Ingo

    2015-03-01

    The implantation of cardiac assist devices is associated with poor outcome in patients with multiple organ failure and unknown neurologic status. Therefore, temporary left ventricular assist devices (LVAD) using, for example, extracorporeal centrifugal pumps may provide the chance to further evaluate the patient's clinical course and a potential qualification for implantable LVAD therapy. On the other hand, a main disadvantage of the temporary LVAD implantation is the need for redo surgery, increasing the risk of the final LVAD Implantation. To minimize this drawback of the temporary LVAD implantation, we implanted the temporary LVAD using a minimally invasive technique. The operation was done without cardiopulmonary bypass support, and the temporary LVAD was implanted through upper hemisternotomy and left anterior mini-thoracotomy. The patient recovered from multiple organ failure and was successfully bridged to a permanent LVAD therapy. PMID:25370719

  1. Membrane Based Thermal Control Development

    NASA Technical Reports Server (NTRS)

    Murdoch, Karen

    1997-01-01

    The investigation of the feasibility of using a membrane device as a water boiler for thermal control is reported. The membrane device permits water vapor to escape to the vacuum of space but prevents the loss of liquid water. The vaporization of the water provides cooling to the water loop. This type of cooling device would have application for various types of short duration cooling needs where expenditure of water is allowed and a low pressure source is available such as in space or on a planet's surface. A variety of membrane samples, both hydrophilic and hydrophobic, were purchased to test for this thermal control application. An initial screening test determined if the membrane could pose a sufficient barrier to maintain water against vacuum. Further testing compared the heat transfer performance of those membranes that passed the screening test.

  2. Electrophoresis device

    NASA Technical Reports Server (NTRS)

    Rhodes, P. H.; Snyder, R. S. (Inventor)

    1982-01-01

    A device for separating cellular particles of a sample substance into fractionated streams of different cellular species includes a casing having a distribution chamber, a separation chamber, and a collection chamber. The electrode chambers are separated from the separation chamber interior by means of passages such that flow variations and membrane variations around the slotted portion of the electrode chamber do not enduce flow perturbations into the laminar buffer curtain flowing in the separation chamber. The cellular particles of the sample are separated under the influence of the electrical field and the separation chamber into streams of different cellular species. The streams of separated cells enter a partition array in the collection chamber where they are fractionated and collected.

  3. Microfluidic Cell Culture Device

    NASA Technical Reports Server (NTRS)

    Takayama, Shuichi (Inventor); Cabrera, Lourdes Marcella (Inventor); Heo, Yun Seok (Inventor); Smith, Gary Daniel (Inventor)

    2014-01-01

    Microfluidic devices for cell culturing and methods for using the same are disclosed. One device includes a substrate and membrane. The substrate includes a reservoir in fluid communication with a passage. A bio-compatible fluid may be added to the reservoir and passage. The reservoir is configured to receive and retain at least a portion of a cell mass. The membrane acts as a barrier to evaporation of the bio-compatible fluid from the passage. A cover fluid may be added to cover the bio-compatible fluid to prevent evaporation of the bio-compatible fluid.

  4. Bacteria/virus filter membrane

    NASA Technical Reports Server (NTRS)

    Lysaght, M. S.; Goodwin, F.; Roebelen, G.

    1977-01-01

    Hollow acrylate fiber membrane that filters bacterial and viral organisms can be used with closed-cycle life-support systems for underwater habitations or laboratories. Membrane also has applications in fields of medicine, gnotobiotics, pharmaceutical production, and industries and research facilities that require sterile water. Device eliminates need for strong chemicals or sterilizing agents, thereby reducing costs.

  5. Advanced underwater lift device

    NASA Technical Reports Server (NTRS)

    Flanagan, David T.; Hopkins, Robert C.

    1993-01-01

    Flexible underwater lift devices ('lift bags') are used in underwater operations to provide buoyancy to submerged objects. Commercially available designs are heavy, bulky, and awkward to handle, and thus are limited in size and useful lifting capacity. An underwater lift device having less than 20 percent of the bulk and less than 10 percent of the weight of commercially available models was developed. The design features a dual membrane envelope, a nearly homogeneous envelope membrane stress distribution, and a minimum surface-to-volume ratio. A proof-of-concept model of 50 kg capacity was built and tested. Originally designed to provide buoyancy to mock-ups submerged in NASA's weightlessness simulators, the device may have application to water-landed spacecraft which must deploy flotation upon impact, and where launch weight and volume penalties are significant. The device may also be useful for the automated recovery of ocean floor probes or in marine salvage applications.

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

    PubMed

    Praveen, Prashant; Loh, Kai-Chee

    2015-12-01

    A two-phase partitioning membrane bioreactor (TPPMB) was designed and operated for treatment of high strength phenolic wastewater through extraction/stripping and concomitant biodegradation. Tributyl phosphate dissolved in kerosene was used as the organic phase, sodium hydroxide as the stripping phase and Pseudomonas putida for biodegradation. In a semi-dispersive approach, organic phase dispersed in the stripping solution was contacted with wastewater through semi-permeable membranes for removal of phenol from wastewater, while the microorganisms were inoculated directly into the wastewater for biodegradation. The TPPMB exhibited high phenol removal rates, and phenol concentrations of 1000-3000mg/L were reduced to undetected amounts within 2-4h. Up to 80% phenol was recovered through extraction, while the remaining was metabolized by the microorganisms. Phenol recovery in the TPPMB was enhanced by increasing the mass transfer rate of phenol through the membranes, and it was also estimated that phenol diffusion through the aqueous boundary layer on the tube side was the rate limiting step. The flexibility in adjusting inoculation time in the TPPMB prevented microorganisms from adverse effects of substrate inhibition, which facilitated complete removal of phenol from the wastewater. TPPMB retained the advantages of both solvent extraction and biodegradation, and it can be highly promising for the treatment of toxic industrial wastewater. PMID:26210322

  7. Highly Efficient Capture and Enumeration of Low Abundance Prostate Cancer Cells Using Prostate-Specific Membrane Antigen Aptamers Immobilized to a Polymeric Microfluidic Device

    PubMed Central

    Dharmasiri, Udara; Balamurugan, Subramanian; Adams, André A.; Okagbare, Paul I.; Obubuafo, Annie; Soper, Steven A.

    2010-01-01

    Prostate tumor cells over-express a prostate specific membrane antigen (PSMA) that can be used as a marker to select these cells from highly heterogeneous clinical samples, even when found in low abundance. Antibodies and aptamers have been developed that specifically bind to PSMA. In this study, anti-PSMA aptamers were immobilized onto the surface of a capture bed poised within a poly(methyl methacrylate), PMMA, microchip, which was fabricated into a high throughput micro-sampling unit (HTMSU) used for the selective isolation of rare circulating prostate tumor cells resident in a peripheral blood matrix. The HTMSU capture bed consisted of 51 ultra-high aspect ratio parallel curvilinear channels with a width similar to the prostate cancer cell dimensions. The surface density of the PSMA-specific aptamers on a UV-modified PMMA microfluidic capture bed surface was determined to be 8.4 × 1012 molecules/cm2. Using a linear velocity for optimal cell capture in the aptamer-tethered HTMSU (2.5 mm/s), a recovery of 90% of LNCaP cells (prostate cancer cell line; used as a model in this example) was found. Due to the low abundance of these cells, the input volume required was 1 mL and this could be processed in approximately 29 min using an optimized linear flow rate of 2.5 mm/s. Captured cells were subsequently released intact from the affinity surface using 0.25% (w/v) trypsin followed by counting individual cells using a contact conductivity sensor integrated into the HTMSU that provided high detection and sampling efficiency (~100%) and did not require staining of the cells for enumeration. PMID:19722212

  8. Modeling flow in nanoporous, membrane reservoirs and interpretation of coupled fluxes

    NASA Astrophysics Data System (ADS)

    Geren, Filiz

    The average pore size in unconventional, tight-oil reservoirs is estimated to be less than 100 nm. At this pore size, Darcy flow is no longer the dominating flow mechanism and a combination of diffusive flows determines the flow characteristics. Concentration driven self-diffusion has been well known and included in the flow and transport models in porous media. However, when the sizes of the pores and pore-throats decrease down to the size of the hydrocarbon molecules, the porous medium acts like a semi-permeable membrane, and the size of the pore openings dictates the direction of transport between adjacent pores. Accordingly, characterization of flow and transport in tight unconventional plays requires understanding of their membrane properties. This Master of Science thesis first highlights the membrane properties of nanoporous, unconventional reservoirs and then discusses how filtration effects can be incorporated into the models of transport in nanoporous media within the coupled flux concept. The effect of filtration on fluid composition and its impact on black-oil fluid properties like bubble point pressure is also demonstrated. To define filtration and filtration pressure in unconventional, tight-oil reservoirs, analogy to chemical osmosis is applied two pore systems connected with a pore throat, which shows membrane properties. Because the pore throat selectivity permits the passage of fluid molecules by their sizes, given a filtration pressure difference between the two pore systems, the concentration difference between the systems is determined by flash calculations. The results are expressed in the form of filtration (membrane) efficiency, which is essential parameter to define coupled fluxes for porous media flow.

  9. Nanoengineered field induced charge separation membranes manufacture thereof

    DOEpatents

    O'Brien, Kevin C.; Haslam, Jeffery J.; Bourcier, William L.; Floyd, III, William Clary

    2016-08-02

    A device according to one embodiment includes a porous membrane having a surface charge and pore configuration characterized by a double layer overlap effect being present in pores of the membrane, where the porous membrane includes functional groups that preferentially interact with either cations or anions. A device according to another embodiment includes a porous membrane having a surface charge in pores thereof sufficient to impart anion or cation selectivity in the pores. Additional devices, systems and methods are also presented.

  10. Evolution of Barrier Membranes in Periodontal Regeneration-"Are the third Generation Membranes really here?".

    PubMed

    Sam, George; Pillai, Baiju Radhamoni Madhavan

    2014-12-01

    In the last decades, Guide Tissue Regeneration (GTR) technique has been applied for the treatment of various periodontal defects such as intrabony defects, furcation involvements and localized gingival recession defects. From early days of using membranes with the simple aim of minimizing toxic response in the host, membranes have come a long way. Third generation membranes not only act as barriers but also as delivery devices to release specific agents. Many clinical trials have focused on using membranes as delivery devices for antibiotics and growth factors. In this article we take a brief look at the evolution of barrier membranes and future avenues with regard to third generation membranes. PMID:25654055

  11. In-membrane micro fuel cell

    DOEpatents

    Omosebi, Ayokunle; Besser, Ronald

    2016-09-06

    An in-membrane micro fuel cell comprises an electrically-insulating membrane that is permissive to the flow of cations, such as protons, and a pair of electrodes deposited on channels formed in the membrane. The channels are arranged as conduits for fluids, and define a membrane ridge between the channels. The electrodes are porous and include catalysts for promoting the liberation of a proton and an electron from a chemical species and/or or the recombination of a proton and an electron with a chemical specie. The fuel cell may be provided a biosensor, an electrochemical sensor, a microfluidic device, or other microscale devices fabricated in the fuel cell membrane.

  12. Membrane tension and membrane fusion.

    PubMed

    Kozlov, Michael M; Chernomordik, Leonid V

    2015-08-01

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

  13. Membrane tethering

    PubMed Central

    Chia, Pei Zhi Cheryl

    2014-01-01

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

  14. Ionization suppression effects with condensed phase membrane introduction mass spectrometry: methods to increase the linear dynamic range and sensitivity.

    PubMed

    Duncan, Kyle D; Vandergrift, Gregory W; Krogh, Erik T; Gill, Chris G

    2015-03-01

    Condensed phase membrane introduction mass spectrometry (CP-MIMS) is an online analytical method that allows for the direct, trace level measurement of a wide range of analytes in complex samples. The technique employs a semi-permeable membrane that transfers analytes from a sample into a flowing acceptor solvent, which is directly infused to an atmospheric pressure ionization source, such as electrospray or atmospheric pressure chemical ionization. While CP-MIMS and variants of the technique have been in the literature for nearly a decade, much of the work has focused on instrument development. Few studies have thoroughly addressed quantitative methods related to detection limits, ionization suppression, or linear dynamic range. We examine ionization suppression in the direct rapid quantitation of analytes by CP-MIMS and introduce several analytical strategies to mitigate these effects, including the novel implementation of a continuously infused internal standard in the acceptor phase solvent, and modulation of acceptor phase flow rate. Several representative analytes were used to evaluate this approach with spiked, complex sample matrices, including primary wastewater effluent and artificial urine. Also reported are improved measured detection limits in the low part-per-trillion range, using a 'stopped-flow' acceptor mode. PMID:25800178

  15. 21 CFR 874.3930 - Tympanostomy tube with semipermeable membrane.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3930... membrane is a device intended to be implanted for ventilation or drainage of the middle ear and for preventing fluids from entering the middle ear cavity. The device is inserted through the tympanic...

  16. 21 CFR 874.3930 - Tympanostomy tube with semipermeable membrane.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3930... membrane is a device intended to be implanted for ventilation or drainage of the middle ear and for preventing fluids from entering the middle ear cavity. The device is inserted through the tympanic...

  17. 21 CFR 874.3930 - Tympanostomy tube with semipermeable membrane.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3930... membrane is a device intended to be implanted for ventilation or drainage of the middle ear and for preventing fluids from entering the middle ear cavity. The device is inserted through the tympanic...

  18. 21 CFR 874.3930 - Tympanostomy tube with semipermeable membrane.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3930... membrane is a device intended to be implanted for ventilation or drainage of the middle ear and for preventing fluids from entering the middle ear cavity. The device is inserted through the tympanic...

  19. 21 CFR 874.3930 - Tympanostomy tube with semipermeable membrane.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3930... membrane is a device intended to be implanted for ventilation or drainage of the middle ear and for preventing fluids from entering the middle ear cavity. The device is inserted through the tympanic...

  20. Membrane Processes.

    PubMed

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

    2015-10-01

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

  1. Membrane Processes.

    PubMed

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

    2016-10-01

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

  2. Multicomponent membranes

    DOEpatents

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

    1988-01-01

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

  3. Method of retrieving a liquid sample, a suction lysimeter, a portable suction lysimeter, a lysimeter system, and a deep lysimeter

    DOEpatents

    Hubbell, Joel M.; Sisson, James B.

    2003-08-26

    A method of retrieving a liquid sample comprises providing a portable lysimeter including a semi-permeable membrane and a chamber in fluid communication with the semi-permeable membrane; making a hole at a site from which a liquid sample is desired; evacuating the chamber by applying a vacuum to the chamber; lowering the portable lysimeter into the hole; obtaining a sample in the chamber; and retrieving the lysimeter from the bore; wherein it is not necessary to backfill the bore. A portable lysimeter includes a semi-permeable member and a chamber in fluid communication with the semi-permeable membrane.

  4. Microreactor array device.

    PubMed

    Wiktor, Peter; Brunner, Al; Kahn, Peter; Qiu, Ji; Magee, Mitch; Bian, Xiaofang; Karthikeyan, Kailash; LaBaer, Joshua

    2015-01-01

    We report a device to fill an array of small chemical reaction chambers (microreactors) with reagent and then seal them using pressurized viscous liquid acting through a flexible membrane. The device enables multiple, independent chemical reactions involving free floating intermediate molecules without interference from neighboring reactions or external environments. The device is validated by protein expressed in situ directly from DNA in a microarray of ~10,000 spots with no diffusion during three hours incubation. Using the device to probe for an autoantibody cancer biomarker in blood serum sample gave five times higher signal to background ratio compared to standard protein microarray expressed on a flat microscope slide. Physical design principles to effectively fill the array of microreactors with reagent and experimental results of alternate methods for sealing the microreactors are presented. PMID:25736721

  5. Microreactor Array Device

    PubMed Central

    Wiktor, Peter; Brunner, Al; Kahn, Peter; Qiu, Ji; Magee, Mitch; Bian, Xiaofang; Karthikeyan, Kailash; LaBaer, Joshua

    2015-01-01

    We report a device to fill an array of small chemical reaction chambers (microreactors) with reagent and then seal them using pressurized viscous liquid acting through a flexible membrane. The device enables multiple, independent chemical reactions involving free floating intermediate molecules without interference from neighboring reactions or external environments. The device is validated by protein expressed in situ directly from DNA in a microarray of ~10,000 spots with no diffusion during three hours incubation. Using the device to probe for an autoantibody cancer biomarker in blood serum sample gave five times higher signal to background ratio compared to standard protein microarray expressed on a flat microscope slide. Physical design principles to effectively fill the array of microreactors with reagent and experimental results of alternate methods for sealing the microreactors are presented. PMID:25736721

  6. Microreactor Array Device

    NASA Astrophysics Data System (ADS)

    Wiktor, Peter; Brunner, Al; Kahn, Peter; Qiu, Ji; Magee, Mitch; Bian, Xiaofang; Karthikeyan, Kailash; Labaer, Joshua

    2015-03-01

    We report a device to fill an array of small chemical reaction chambers (microreactors) with reagent and then seal them using pressurized viscous liquid acting through a flexible membrane. The device enables multiple, independent chemical reactions involving free floating intermediate molecules without interference from neighboring reactions or external environments. The device is validated by protein expressed in situ directly from DNA in a microarray of ~10,000 spots with no diffusion during three hours incubation. Using the device to probe for an autoantibody cancer biomarker in blood serum sample gave five times higher signal to background ratio compared to standard protein microarray expressed on a flat microscope slide. Physical design principles to effectively fill the array of microreactors with reagent and experimental results of alternate methods for sealing the microreactors are presented.

  7. 21 CFR 868.5610 - Membrane lung for long-term pulmonary support.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Membrane lung for long-term pulmonary support. 868... SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5610 Membrane lung for long-term pulmonary support. (a) Identification. A membrane lung for long-term pulmonary...

  8. 21 CFR 868.5610 - Membrane lung for long-term pulmonary support.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Membrane lung for long-term pulmonary support. 868... SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5610 Membrane lung for long-term pulmonary support. (a) Identification. A membrane lung for long-term pulmonary...

  9. 21 CFR 868.5610 - Membrane lung for long-term pulmonary support.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Membrane lung for long-term pulmonary support. 868... SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5610 Membrane lung for long-term pulmonary support. (a) Identification. A membrane lung for long-term pulmonary...

  10. 21 CFR 868.5610 - Membrane lung for long-term pulmonary support.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Membrane lung for long-term pulmonary support. 868... SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5610 Membrane lung for long-term pulmonary support. (a) Identification. A membrane lung for long-term pulmonary...

  11. Immobilized fluid membranes for gas separation

    DOEpatents

    Liu, Wei; Canfield, Nathan L; Zhang, Jian; Li, Xiaohong Shari; Zhang, Jiguang

    2014-03-18

    Provided herein are immobilized liquid membranes for gas separation, methods of preparing such membranes and uses thereof. In one example, the immobilized membrane includes a porous metallic host matrix and an immobilized liquid fluid (such as a silicone oil) that is immobilized within one or more pores included within the porous metallic host matrix. The immobilized liquid membrane is capable of selective permeation of one type of molecule (such as oxygen) over another type of molecule (such as water). In some examples, the selective membrane is incorporated into a device to supply oxygen from ambient air to the device for electrochemical reactions, and at the same time, to block water penetration and electrolyte loss from the device.

  12. Crystalline Membranes

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  13. Development of a passive sampler based on a polymer inclusion membrane for total ammonia monitoring in freshwaters.

    PubMed

    Almeida, M Inês G S; Silva, Adélia M L; Coleman, Rhys A; Pettigrove, Vincent J; Cattrall, Robert W; Kolev, Spas D

    2016-05-01

    A passive sampler for determining the time-weighted average total ammonia (i.e. molecular ammonia and the ammonium cation) concentration (C TWA) in freshwaters, which incorporated a polymer inclusion membrane (PIM) as a semi-permeable barrier separating the aqueous source solution from the receiving solution (i.e. 0.8 mol L(-1) HCl), was developed for the first time. The PIM was composed of dinonylnaphthalene sulfonic acid (DNNS) as a carrier, poly (vinyl chloride) (PVC) as a base polymer and 1-tetradecanol as a modifier. Its optimal composition was found to be 35 wt% commercial DNNS, 55 wt% PVC and 10 wt% 1-tetradecanol. The effect of environmental variables such as the water matrix, pH and temperature were also studied using synthetic freshwaters. The passive sampler was calibrated under laboratory conditions using synthetic freshwaters and exhibited a linear response within the concentration range 0.59-2.8 mg L(-1) NH4(+) (0.46-2.1 mg N L(-1)) at 20 °C. The performance of the sampler was further investigated under field conditions over 7 days. A strong correlation between spot sampling and passive sampling was achieved, thus providing a proof-of-concept for the passive sampler for reliably measuring the C(TWA) of total ammonia in freshwaters, which can be used as an indicator in tracking sources of faecal contamination in stormwater drains. PMID:26873214

  14. Biological membranes

    PubMed Central

    Watson, Helen

    2015-01-01

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

  15. Membranous nephropathy

    MedlinePlus

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

  16. Photovoltaic device

    DOEpatents

    Reese, Jason A.; Keenihan, James R.; Gaston, Ryan S.; Kauffmann, Keith L.; Langmaid, Joseph A.; Lopez, Leonardo C.; Maak, Kevin D.; Mills, Michael E.; Ramesh, Narayan; Teli, Samar R.

    2015-06-02

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device with a multilayered photovoltaic cell assembly and a body portion joined at an interface region and including an intermediate layer, at least one interconnecting structural member, relieving feature, unique component geometry, or any combination thereof.

  17. Photovoltaic device

    SciTech Connect

    Reese, Jason A.; Keenihan, James R.; Gaston, Ryan S.; Kauffmann, Keith L.; Langmaid, Joseph A.; Lopez, Leonardo C.; Maak, Kevin D.; Mills, Michael E.; Ramesh, Narayan; Teli, Samar R.

    2015-09-01

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device (10) with a multilayered photovoltaic cell assembly (100) and a body portion (200) joined at an interface region (410) and including an intermediate layer (500), at least one interconnecting structural member (1500), relieving feature (2500), unique component geometry, or any combination thereof.

  18. Membrane with internal passages to permit fluid flow and an electrochemical cell containing the same

    NASA Technical Reports Server (NTRS)

    Cisar, Alan J. (Inventor); Gonzalez-Martin, Anuncia (Inventor); Hitchens, G. Duncan (Inventor); Murphy, Oliver J. (Inventor)

    1997-01-01

    The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface, an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane for purposes of hydration.

  19. Boundary layer control device for duct silencers

    NASA Technical Reports Server (NTRS)

    Schmitz, Fredric H. (Inventor); Soderman, Paul T. (Inventor)

    1993-01-01

    A boundary layer control device includes a porous cover plate, an acoustic absorber disposed under the porous cover plate, and a porous flow resistive membrane interposed between the porous cover plate and the acoustic absorber. The porous flow resistive membrane has a flow resistance low enough to permit sound to enter the acoustic absorber and high enough to damp unsteady flow oscillations.

  20. Ion transport membrane module and vessel system

    DOEpatents

    Stein, VanEric Edward; Carolan, Michael Francis; Chen, Christopher M.; Armstrong, Phillip Andrew; Wahle, Harold W.; Ohrn, Theodore R.; Kneidel, Kurt E.; Rackers, Keith Gerard; Blake, James Erik; Nataraj, Shankar; van Doorn, Rene Hendrik Elias; Wilson, Merrill Anderson

    2008-02-26

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; and (c) one or more gas manifolds in flow communication with interior regions of the membrane modules and with the exterior of the pressure vessel.The ion transport membrane system may be utilized in a gas separation device to recover oxygen from an oxygen-containing gas or as an oxidation reactor to oxidize compounds in a feed gas stream by oxygen permeated through the mixed metal oxide ceramic material of the membrane modules.

  1. Ion transport membrane module and vessel system

    DOEpatents

    Stein, VanEric Edward; Carolan, Michael Francis; Chen, Christopher M.; Armstrong, Phillip Andrew; Wahle, Harold W.; Ohrn, Theodore R.; Kneidel, Kurt E.; Rackers, Keith Gerard; Blake, James Erik; Nataraj, Shankar; van Doorn, Rene Hendrik Elias; Wilson, Merrill Anderson

    2007-02-20

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; and (c) one or more gas manifolds in flow communication with interior regions of the membrane modules and with the exterior of the pressure vessel. The ion transport membrane system may be utilized in a gas separation device to recover oxygen from an oxygen-containing gas or as an oxidation reactor to oxidize compounds in a feed gas stream by oxygen permeated through the mixed metal oxide ceramic material of the membrane modules.

  2. Ion transport membrane module and vessel system

    DOEpatents

    Stein, VanEric Edward; Carolan, Michael Francis; Chen, Christopher M.; Armstrong, Phillip Andrew; Wahle, Harold W.; Ohrn, Theodore R.; Kneidel, Kurt E.; Rackers, Keith Gerard; Blake, James Erik; Nataraj, Shankar; Van Doorn, Rene Hendrik Elias; Wilson, Merrill Anderson

    2012-02-14

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an exterior, an inlet, and an outlet; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region, wherein any inlet and any outlet of the pressure vessel are in flow communication with exterior regions of the membrane modules; and (c) one or more gas manifolds in flow communication with interior regions of the membrane modules and with the exterior of the pressure vessel. The ion transport membrane system may be utilized in a gas separation device to recover oxygen from an oxygen-containing gas or as an oxidation reactor to oxidize compounds in a feed gas stream by oxygen permeated through the mixed metal oxide ceramic material of the membrane modules.

  3. Electronic polymers in lipid membranes

    PubMed Central

    Johansson, Patrik K.; Jullesson, David; Elfwing, Anders; Liin, Sara I.; Musumeci, Chiara; Zeglio, Erica; Elinder, Fredrik; Solin, Niclas; Inganäs, Olle

    2015-01-01

    Electrical interfaces between biological cells and man-made electrical devices exist in many forms, but it remains a challenge to bridge the different mechanical and chemical environments of electronic conductors (metals, semiconductors) and biosystems. Here we demonstrate soft electrical interfaces, by integrating the metallic polymer PEDOT-S into lipid membranes. By preparing complexes between alkyl-ammonium salts and PEDOT-S we were able to integrate PEDOT-S into both liposomes and in lipid bilayers on solid surfaces. This is a step towards efficient electronic conduction within lipid membranes. We also demonstrate that the PEDOT-S@alkyl-ammonium:lipid hybrid structures created in this work affect ion channels in the membrane of Xenopus oocytes, which shows the possibility to access and control cell membrane structures with conductive polyelectrolytes. PMID:26059023

  4. Use of Chemical Analysis and Assays of Semipermeable Membrane Devices Extracts to Assess the Response of Bioavailable Organic Pollutants in Streams to Urbanization in Six Metropolitan Areas of the United States

    USGS Publications Warehouse

    Bryant, Wade L.; Goodbred, Steve L.; Leiker, Thomas L.; Inouye, Laura; Johnson, B. Thomas

    2007-01-01

    Studies to assess the effects of urbanization on stream ecosystems are being conducted as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. The overall objectives of these studies are to (1) determine how hydrologic, geomorphic, water quality, habitat, and biological characteristics respond to land-use changes associated with urbanization in specific environmental settings, and (2) compare these responses across environmental settings. As part of an integrated assessment, semipermeable membrane devices (SPMDs) were deployed in streams along a gradient of urban land-use intensity in and around Atlanta, Georgia; Raleigh-Durham, North Carolina; and Denver-Fort Collins, Colorado, in 2003; and Dallas-Fort Worth, Texas; Milwaukee-Green Bay, Wisconsin; and Portland, Oregon, in 2004. Sites were selected to avoid point-source discharge and to minimize natural variability within each of the six metropolitan areas. In addition to standard chemical analysis for hydrophobic organic contaminants, three assays were used to address mixtures and potential toxicity: (1) Fluoroscan provides an estimate of the total concentration of polycyclic aromatic hydrocarbons (PAHs); (2) the P450RGS assay indicates the presence and levels of aryl hydrocarbon receptor agonists; and (3) Microtox? measures toxicological effects on photo-luminescent bacteria. Of the 140 compounds targeted or identified by gas chromatography/mass spectrometry analysis in this study, 67 were not detected. In terms of numbers and types of compounds, the following were detected: 2 wood preservatives, 6 insecticides (parent compounds), 5 herbicides, 22 polycyclic aromatic hydrocarbons, 2 dibenzofurans, 4 polychlorinated biphenyls, 7 compounds associated with fragrances or personal care products, 4 steroids associated with wastewater, 5 polydibromated diphenyl ethers (flame retardants), 3 plasticizers, 3 antimicrobials/disinfectants, and 3 detergent metabolites. Of the 73 compounds

  5. Microfluidic Device

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Lin, Jeffrey Chun-Hui (Inventor); Kasdan, Harvey (Inventor)

    2015-01-01

    Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.

  6. Microfluidic Device

    NASA Technical Reports Server (NTRS)

    Tai, Yu-Chong (Inventor); Zheng, Siyang (Inventor); Lin, Jeffrey Chun-Hui (Inventor); Kasdan, Harvey L. (Inventor)

    2016-01-01

    Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.

  7. Sealing device

    SciTech Connect

    Garcia-Crespo, Andres Jose

    2013-12-10

    A sealing device for sealing a gap between a dovetail of a bucket assembly and a rotor wheel is disclosed. The sealing device includes a cover plate configured to cover the gap and a retention member protruding from the cover plate and configured to engage the dovetail. The sealing device provides a seal against the gap when the bucket assemply is subjected to a centrifugal force.

  8. Membrane magic

    SciTech Connect

    Buecker, B.

    2005-09-01

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

  9. BRAKE DEVICE

    DOEpatents

    O'Donnell, T.J.

    1959-03-10

    A brake device is described for utilization in connection with a control rod. The device comprises a pair of parallelogram link mechanisms, a control rod moveable rectilinearly therebetween in opposite directions, and shoes resiliently supported by the mechanism for frictional engagement with the control rod.

  10. Electrochromic devices

    DOEpatents

    Allemand, Pierre M.; Grimes, Randall F.; Ingle, Andrew R.; Cronin, John P.; Kennedy, Steve R.; Agrawal, Anoop; Boulton, Jonathan M.

    2001-01-01

    An electrochromic device is disclosed having a selective ion transport layer which separates an electrochemically active material from an electrolyte containing a redox active material. The devices are particularly useful as large area architectural and automotive glazings due to there reduced back reaction.

  11. Detection of Molecular Charges at Cell Membrane

    NASA Astrophysics Data System (ADS)

    Sakata, Toshiya; Miyahara, Yuji

    2008-01-01

    Molecular charges at the cell membrane have been successfully detected using cell-based field-effect devices. Mouse fibroblast cells were adhered to the Si3N4 gate surface of the field-effect devices. The negative charges of sialic acid at the surface of the cell membrane could be detected as a shift of the flatband voltage of the field-effect devices. Quantitative analysis of molecular charges at the cell membrane could be demonstrated in relation to the number of adhered cells on the Si3N4 gate surface. The platform based on the field-effect devices is suitable for a simple, accurate and non-invasive system for cell functional analysis.

  12. Catalytic Membrane Sensors

    SciTech Connect

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  13. PLASMA DEVICE

    DOEpatents

    Gow, J.D.; Wilcox, J.M.

    1961-12-26

    A device is designed for producing and confining highenergy plasma from which neutrons are generated in copious quantities. A rotating sheath of electrons is established in a radial electric field and axial magnetic field produced within the device. The electron sheath serves as a strong ionizing medium to gas introdueed thereto and also functions as an extremely effective heating mechanism to the resulting plasma. In addition, improved confinement of the plasma is obtained by ring magnetic mirror fields produced at the ends of the device. Such ring mirror fields are defined by the magnetic field lines at the ends of the device diverging radially outward from the axis of the device and thereafter converging at spatial annular surfaces disposed concentrically thereabout. (AFC)

  14. A membrane stirrer for product recovery and substrate feeding.

    PubMed

    Femmer, T; Carstensen, F; Wessling, M

    2015-02-01

    During fermentation processes, in situ product recovery (ISPR) using submerged membranes allows a continuous operation mode with effective product removal. Continuous recovery reduces product inhibition and organisms in the reactor are not exposed to changing reaction conditions. For an effective in situ product removal, submerged membrane systems should have a sufficient large membrane area and an anti-fouling concept integrated in a compact device for the limited space in a lab-scale bioreactor. We present a new membrane stirrer with integrated filtration membranes on the impeller blades as well as an integrated gassing concept in an all-in-one device. The stirrer is fabricated by rapid prototyping and is equipped with a commercial micromesh membrane. Filtration performance is tested using a yeast cell suspension with different stirring speeds and aeration fluxes. We reduce membrane fouling by backflushing through the membrane with the product stream. PMID:25212847

  15. [Membranous nephropathy].

    PubMed

    Mercadal, Lucile

    2013-12-01

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

  16. Membrane species mobility under in-lipid-membrane forced convection.

    PubMed

    Hu, Shu-Kai; Huang, Ling-Ting; Chao, Ling

    2016-08-17

    Processing and managing cell membrane proteins for characterization while maintaining their intact structure is challenging. Hydrodynamic flow has been used to transport membrane species in supported lipid bilayers (SLBs) where the hydrophobic cores of the membrane species can be protected during processing. However, the forced convection mechanism of species embedded in lipid bilayers is still unclear. Developing a controlled SLB platform with a practical model to predict the membrane species mobility in the platform under in-lipid-membrane forced convection is imperative to ensure the practical applicability of SLBs in processing and managing membrane species with various geometrical properties. The mobility of membrane species is affected by the driving force from the aqueous environment in addition to the frictions from the lipid bilayer, in which both lipid leaflets may exhibit different speeds relative to that of the moving species. In this study, we developed a model, based on the applied driving force and the possible frictional resistances that the membrane species encounter, to predict how the mobility under in-lipid-membrane forced convection is influenced by the sizes of the species' hydrophilic portion in the aqueous environment and the hydrophobic portion embedded in the membrane. In addition, we used a microfluidic device for controlling the flow to arrange the lipid membrane and the tested membrane species in the desirable locations in order to obtain a SLB platform which can provide clear mobility responses of the species without disturbance from the species dispersion effect. The model predictions were consistent with the experimental observations, with the sliding friction coefficient between the upper leaflet and the hydrophilic portion of the species as the only regressed parameter. The result suggests that not only the lateral drag frictions from the lipid layers but also the sliding frictions between the species and the lipid layer planes

  17. Nanoporous materials for biomedical devices.

    SciTech Connect

    Adiga, S. P.; Curtiss, L. A.; Elam, J. W.; Pellin, M. J.; Shih, C.-C.; Shin, C.-M.; Lin, S.-J.; Su, Y.-Y.; Gittard, S. D.; Zhang, J.; Narayan, R. J.; National Yang-Ming Univ.; Taipei Medical Univ.; Univ. of North Carolina at Chapel Hill

    2008-01-01

    Nanoporous materials are currently being developed for use in implantable drug delivery systems, bioartificial organs, and other novel medical devices. Advances in nanofabrication have made it possible to precisely control the pore size, pore distribution, porosity, and chemical properties of pores in nanoporous materials. As a result, these materials are attractive for regulating and sensing transport at the molecular level. In this work, the use of nanoporous membranes for biomedical applications is reviewed. The basic concepts underlying membrane transport are presented in the context of design considerations for efficient size sorting. Desirable properties of nanoporous membranes used in implantable devices, including biocompatibility and antibiofouling behavior, are also discussed. In addition, the use of surface modification techniques to improve the function of nanoporous membranes is reviewed. An intriguing possibility involves functionalizing nanoporous materials with smart polymers in order to modulate biomolecular transport in response to pH, temperature, ionic concentration, or other stimuli. These efforts open up avenues to develop smart medical devices that respond to specific physiological conditions.

  18. Gripping device

    NASA Technical Reports Server (NTRS)

    Parma, George F. (Inventor)

    1989-01-01

    This invention relates to a gripping device, and more particularly to one with a large moment carrying capability for handling long workpieces of various diameters and which can be particularly used as an end effector on a robotic arm.

  19. Assistive Devices

    MedlinePlus

    ... center provides information on VA benefits for assistive technology. Medicare − Benefits may include assistive devices, such as ... a Web site that provides information about assistive technology products. Go to the “Products” section to find ...

  20. Device Performance

    SciTech Connect

    Not Available

    2006-06-01

    In the Device Performance group, within the National Center for Photovoltaic's Measurements and Characterization Division, we measure the performance of PV cells and modules with respect to standard reporting conditions--defined as a reference temperature (25 C), total irradiance (1000 Wm-2), and spectral irradiance distribution (IEC standard 60904-3). Typically, these are ''global'' reference conditions, but we can measure with respect to any reference set. To determine device performance, we conduct two general categories of measurements: spectral responsivity (SR) and current versus voltage (I-V). We usually perform these measurements using standard procedures, but we develop new procedures when required by new technologies. We also serve as an independent facility for verifying device performance for the entire PV community. We help the PV community solve its special measurement problems, giving advice on solar simulation, instrumentation for I-V measurements, reference cells, measurement procedures, and anomalous results. And we collaborate with researchers to analyze devices and materials.

  1. Lipid membranes for membrane proteins.

    PubMed

    Kukol, Andreas

    2015-01-01

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

  2. Metallization of bacterial cellulose for electrical and electronic device manufacture

    SciTech Connect

    Evans, Barbara R.; O'Neill, Hugh M.; Jansen, Valerie Malyvanh; Woodward, Jonathan

    2006-01-17

    The employment of metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The fuel cell includes an electrolyte membrane comprising a membrane support structure comprising bacterial cellulose, an anode disposed on one side of the electrolyte membrane, and a cathode disposed on an opposite side of the electrolyte membrane. At least one of the anode and the cathode comprises an electrode support structure comprising bacterial cellulose, and a catalyst disposed in or on the electrode support structure.

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

    DOEpatents

    Way, J. Douglas; Hatlevik, Oyvind

    2014-07-15

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

  4. 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.

  5. Omniphobic Membrane for Robust Membrane Distillation

    SciTech Connect

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

    2014-11-01

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

  6. Synthetic membranes for water purification: status and future.

    PubMed

    Fane, Anthony G; Wang, Rong; Hu, Matthew X

    2015-03-01

    Membrane technology offers the best options to "drought proof" mankind on an increasingly thirsty planet by purifying seawater or used (waste) water. Although desalination by reverse osmosis (RO) and wastewater treatment by membrane bioreactors are well established the various membrane technologies still need to be significantly improved in terms of separation properties, energy demand and costs. We can now define the ideal characteristics of membranes and advances in material science and novel chemistries are leading to increasingly effective membranes. However developments in membranes must be matched by improved device design and membrane engineering. It is likely that limitations in fluid mechanics and mass transfer will define the upper bounds of membrane performance. Nevertheless major advances and growth over the next 20 years can be anticipated with RO remaining as the key to desalination and reclamation, with other membrane processes growing in support and in niche areas. PMID:25613795

  7. Ventricular assist devices in pediatrics

    PubMed Central

    Fuchs, A; Netz, H

    2001-01-01

    The implantation of a mechanical circulatory device for end-stage ventricular failure is a possible therapeutic approach in adult and pediatric cardiac surgery and cardiology. The aim of this article is to present mechanical circulatory assist devices used in infants and children with special emphasis on extracorporeal membrane oxygenation, Berlin Heart assist device, centrifugal pump and Medos assist device. The success of long-term support with implantable ventricular assist devices in adults and children has led to their increasing use as a bridge to transplantation in patients with otherwise non-treatable left ventricular failure, by transforming a terminal phase heart condition into a treatable cardiopathy. Such therapy allows rehabilitation of patients before elective cardiac transplantation (by removing contraindications to transplantation mainly represented by organ impairment) or acting as a bridge to recovery of the native left ventricular function (depending on underlying cardiac disease). Treatment may also involve permanent device implantation when cardiac transplantation is contraindicated. Indications for the implantation of assisted circulation include all states of cardiac failure that are reversible within a variable period of time or that require heart transplantation. This article will address the current status of ventricular assist devices by examining historical aspects of its development, current technical issues and clinical features of pediatric ventricular assist devices, including indications and contraindications for support. PMID:22368605

  8. Infrared microthermography of microfabricated devices

    NASA Astrophysics Data System (ADS)

    Furstenberg, Robert; Kendziora, C. A.; Stepnowski, Stanley V.; McGill, R. Andrew

    2007-06-01

    We report a new experimental apparatus for infrared microthermography applicable to a wide class of samples including semitransparent ones and perforated devices. This setup is particularly well suited for the thermography of microfabricated devices. Traditionally, temperature calibration is performed using calibration hot plates, but this is not applicable to transmissive samples. In this work a custom designed miniature calibration oven in conjunction with spatial filtering is used to obtain accurate static and transient temperature maps of actively heated devices. The procedure does not require prior knowledge of the emissivity. Calibration and image processing algorithms are discussed and analyzed. We show that relatively inexpensive uncooled bolometer arrays can be a suitable detector choice in certain radiometric applications. As an example, we apply this method in the analysis of temperature profiles of an actively heated microfabricated preconcentrator device that incorporates a perforated membrane and is used in trace detection of illicit substances.

  9. Infrared microthermography of microfabricated devices

    SciTech Connect

    Furstenberg, Robert; Kendziora, C. A.; Stepnowski, Stanley V.; McGill, R. Andrew

    2007-06-15

    We report a new experimental apparatus for infrared microthermography applicable to a wide class of samples including semitransparent ones and perforated devices. This setup is particularly well suited for the thermography of microfabricated devices. Traditionally, temperature calibration is performed using calibration hot plates, but this is not applicable to transmissive samples. In this work a custom designed miniature calibration oven in conjunction with spatial filtering is used to obtain accurate static and transient temperature maps of actively heated devices. The procedure does not require prior knowledge of the emissivity. Calibration and image processing algorithms are discussed and analyzed. We show that relatively inexpensive uncooled bolometer arrays can be a suitable detector choice in certain radiometric applications. As an example, we apply this method in the analysis of temperature profiles of an actively heated microfabricated preconcentrator device that incorporates a perforated membrane and is used in trace detection of illicit substances.

  10. Infrared microthermography of microfabricated devices.

    PubMed

    Furstenberg, Robert; Kendziora, C A; Stepnowski, Stanley V; McGill, R Andrew

    2007-06-01

    We report a new experimental apparatus for infrared microthermography applicable to a wide class of samples including semitransparent ones and perforated devices. This setup is particularly well suited for the thermography of microfabricated devices. Traditionally, temperature calibration is performed using calibration hot plates, but this is not applicable to transmissive samples. In this work a custom designed miniature calibration oven in conjunction with spatial filtering is used to obtain accurate static and transient temperature maps of actively heated devices. The procedure does not require prior knowledge of the emissivity. Calibration and image processing algorithms are discussed and analyzed. We show that relatively inexpensive uncooled bolometer arrays can be a suitable detector choice in certain radiometric applications. As an example, we apply this method in the analysis of temperature profiles of an actively heated microfabricated preconcentrator device that incorporates a perforated membrane and is used in trace detection of illicit substances. PMID:17614631