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Sample records for aao tubular membranes

  1. Effect of Processing Parameters on Pore Structure and Thickness of Anodic Aluminum Oxide (AAO) Tubular Membranes.

    PubMed

    Belwalkar, A; Grasing, E; Van Geertruyden, W; Huang, Z; Misiolek, W Z

    2008-07-01

    Nanoporous anodic aluminum oxide (AAO) tubular membranes were fabricated from aluminum alloy tubes in sulfuric and oxalic acid electrolytes using a two-step anodization process. The membranes were investigated for characteristics such as pore size, interpore distance and thickness by varying applied voltage and electrolyte concentration. Morphology of the membranes was examined using light optical and scanning electron microscopy and characterized using ImageJ software. Results showed that membranes having narrow pore size and uniform pore distribution with parallel channel arrays were obtained. The pore sizes were ranging from 14 to 24 nm and the wall thicknesses as high as 76 microm. It was found that the pore size increased in direct proportion with the applied voltage and inversely with the electrolyte concentration while the interpore distance increased linearly with the applied voltage. It was also observed that increase in acid concentration increased tubular membrane wall thickness that improved mechanical handling. By using anodic alumina technology, robust ceramic tubes with uniformly distributed pore-structure and parallel nano-channels of lengths and sizes practical for industrial applications were reliably produced in quantity. PMID:19578471

  2. Effect of Processing Parameters on Pore Structure and Thickness of Anodic Aluminum Oxide (AAO) Tubular Membranes

    PubMed Central

    Belwalkar, A.; Grasing, E.; Huang, Z.; Misiolek, W.Z.

    2008-01-01

    Nanoporous anodic aluminum oxide (AAO) tubular membranes were fabricated from aluminum alloy tubes in sulfuric and oxalic acid electrolytes using a two-step anodization process. The membranes were investigated for characteristics such as pore size, interpore distance and thickness by varying applied voltage and electrolyte concentration. Morphology of the membranes was examined using light optical and scanning electron microscopy and characterized using ImageJ software. Results showed that membranes having narrow pore size and uniform pore distribution with parallel channel arrays were obtained. The pore sizes were ranging from 14 to 24 nm and the wall thicknesses as high as 76 µm. It was found that the pore size increased in direct proportion with the applied voltage and inversely with the electrolyte concentration while the interpore distance increased linearly with the applied voltage. It was also observed that increase in acid concentration increased tubular membrane wall thickness that improved mechanical handling. By using anodic alumina technology, robust ceramic tubes with uniformly distributed pore-structure and parallel nano-channels of lengths and sizes practical for industrial applications were reliably produced in quantity. PMID:19578471

  3. 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.

  4. Fabrication and characterization of nanostructured Mg-doped CdS/AAO nanoporous membrane for sensing applications

    NASA Astrophysics Data System (ADS)

    Shaban, Mohamed; Mustafa, Mona; Hamdy, Hany

    2016-04-01

    In this study, Mg-doped CdS nanostructure was deposited onto anodic aluminum oxide (AAO) membrane substrate using sol-gel spin coating method. The AAO membrane was prepared by a two-step anodization process combined with pore widening process. The morphology, chemical composition, and structure of the spin- coated CdS nanostructure have been studied. The morphology of the fabricated AAO membrane and the deposited Mg-doped CdS nanostructure was investigated using scanning electron microscopy (SEM). The SEM of AAO illustrates a typical hexagonal and smooth nanoporous alumina membrane with interpore distance of ~ 100 nm, the pore diameter of ~ 60 nm. SEM of Mgdoped CdS shows porous nanostructured film of CdS nanoparticles. This film well adherents and covers the AAO substrate. The energy dispersive X-ray (EDX) pattern exhibits the signals of Al, O from AAO membrane and Mg, Cd, and S from the deposited CdS. This indicates the high purity of the fabricated membrane and the deposited Mg-doped CdS nanostructure. Using X-ray diffraction (XRD) pattern, Scherrer equation was used to calculate the average crystallite size. Additionally, the texture coefficients and density of dislocations were calculated. The fabricated CdS/AAO was applied to detect glucose of different concentrations. The proposed method has some advantages such as simple technology, low cost of processing, and high throughput. All of these factors facilitate the use of the prepared films in sensing applications.

  5. Self-Cleaning Tubular-Membrane Module

    NASA Technical Reports Server (NTRS)

    Sarbolouki, M. N.

    1983-01-01

    Tubular membranes made self-cleaning with aid of flow reversing valve. Sponge balls scrub membrane surfaces as they travel inside membrane tubes. A four-way flow-reversal valve automatically reverses flow in tubes at preset intervals so sponge balls reciprocate along tubes. Baskets at ends of tubes prevent sponges from escaping. Automatic cleaning feature added to existing membrane processing equipment with minimal modifications.

  6. Tubular Membrane Plant-Growth Unit

    NASA Technical Reports Server (NTRS)

    Dreschel, Thomas W.

    1992-01-01

    Hydroponic system controls nutrient solution for growing crops in space. Pump draws nutrient solution along inside of tubular membrane in pipe from reservoir, maintaining negative pressure in pipe. Roots of plants in slot extract nutrient through membrane within pipe. Crop plants such as wheat, rice, lettuce, tomatoes, soybeans, and beans grown successfully with system.

  7. Pressure driven flow in porous tubular membranes

    NASA Astrophysics Data System (ADS)

    Tilton, Nils; Martinand, Denis; Serre, Eric; Lueptow, Richard

    2011-11-01

    We consider the steady laminar flow of a Newtonian incompressible fluid in a porous tubular membrane with pressure-driven transmembrane flow. Due to its fundamental importance to membrane filtration systems, this flow has been studied extensively both analytically and numerically, yet a robust analytic solution has not been found. The problem is challenging due to the coupling between the transmembrane pressure and velocity with the simultaneous coupling between the axial pressure gradient and the axial velocity. We present a robust analytical solution which incorporates Darcy's law on the membrane surface. The solution is in the form of an asymptotic expansion about a small parameter related to the membrane permeability. We verify the analytical solution with comparison to 2-D spectral direct numerical simulations of ultrafiltration and microfiltration systems with typical operating conditions, as well as extreme cases of cross-flow reversal and axial flow exhaustion. In all cases, the agreement between the analytical and numerical results is excellent. Finally, we use the analytical and numerical results to provide guidelines about when common simplifying assumptions about the permeate flow may be made. Specifically, the assumptions of a parabolic axial velocity profile and uniform transmembrane velocity are valid only for small permeabilities.

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

    DOEpatents

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

    2006-04-04

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

  9. Numerical Observation of a Tubular Phase in Anisotropic Membranes

    SciTech Connect

    Bowick, M.; Falcioni, M.; Thorleifsson, G.

    1997-08-01

    We provide the first numerical evidence for the existence of a tubular phase, predicted by Radzihovsky and Toner (RT), for anisotropic tethered membranes without self-avoidance. Incorporating anisotropy into the bending rigidity of a simple model of a tethered membrane with free boundary conditions, we show that the model indeed has two phase transitions corresponding to the flat-to-tubular and tubular-to-crumpled transitions. For the tubular phase we measure the Flory exponent {nu}{sub F} and the roughness exponent {zeta} . We find {nu}{sub F}=0.305(14) and {zeta}=0.895(60) , which are in reasonable agreement with the theoretical predictions of RT; {nu}{sub F}=1/4 and {zeta}=1 . {copyright} {ital 1997} {ital The American Physical Society}

  10. Enhanced water vapour flow in silica microchannels and interdiffusive water vapour flow through anodic aluminium oxide (AAO) membranes

    NASA Astrophysics Data System (ADS)

    Lei, Wenwen; McKenzie, David R.

    2015-12-01

    Enhanced liquid water flows through carbon nanotubes reinvigorated the study of moisture permeation through membranes and micro- and nano-channels. The study of water vapour through micro-and nano-channels has been neglected even though water vapour is as important as liquid water for industry, especially for encapsulation of electronic devices. Here we measure moisture flow rates in silica microchannels and interdiffusive water vapour flows in anodic aluminium oxide (AAO) membrane channels for the first time. We construct theory for the flow rates of the dominant modes of water transport through four previously defined standard configurations and benchmark it against our new measurements. The findings show that measurements of leak behaviour made using other molecules, such as helium, are not reliable. Single phase water vapour flow is overestimated by a helium measurement, while Washburn or capillary flow is underestimated or for all channels when boundary slip applies, to an extent that depends on the slip length for the liquid phase flows.

  11. Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation.

    PubMed

    Ciambelli, P; Arurault, L; Sarno, M; Fontorbes, S; Leone, C; Datas, L; Sannino, D; Lenormand, P; Du Plouy, S Le Blond

    2011-07-01

    Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects. PMID:21576783

  12. Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation

    NASA Astrophysics Data System (ADS)

    Ciambelli, P.; Arurault, L.; Sarno, M.; Fontorbes, S.; Leone, C.; Datas, L.; Sannino, D.; Lenormand, P.; Le Blond Du Plouy, S.

    2011-07-01

    Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects.

  13. Helium permeation through a silicalite-1 tubular membrane

    NASA Astrophysics Data System (ADS)

    Hernández, M. G.; Salinas-Rodríguez, E.; Gómez, S. A.; Roa-Neri, J. A. E.; Alfaro, S.; Valdés-Parada, F. J.

    2015-06-01

    A silicalite-1 tubular membrane was prepared on the inner surface of a porous α-alumina support. Helium permeation at different feed volumetric flows (11-41 mL/min) with different sweep flow rates (9-90 mL/min) at STP conditions was measured. The molar fraction was obtained as a function of the residence time ratio. The influences of the geometric parameters of the tubular system and the feed flow rates on the permeation through the membrane were investigated. The dependence of the permeances with the residence time ratio was experimentally obtained and we propose that this dependence is a useful design criterion for tubular membrane permeation systems. The best results in this work were obtained for Q He, in / Q N2, in = 0.22 for V SS / V TS = 7.3. Also, the data showed that an appropriate combination of the flows and the area sections of the system resulted in an optimum value for the Péclet number of 0.3. The experimental data were reproduced by numerically solving the Maxwell-Stefan equations under the assumption that transport across the membrane can be modeled in terms of a Robin-type boundary condition.

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

    PubMed

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

    2013-10-25

    For the first time, a tubular asymmetric ceramic-carbonate dual phase membrane was prepared by a centrifugal casting technique and used for high temperature CO2 separation. This membrane shows high CO2 permeation flux and permeance. PMID:24022119

  15. Modification of tubular ceramic membranes with carbon nanotubes using catalytic chemical vapor deposition.

    PubMed

    Tran, Duc Trung; Thieffry, Guillemette; Jacob, Matthieu; Batiot-Dupeyrat, Catherine; Teychene, Benoit

    2015-01-01

    In this study, carbon nanotubes (CNTs) were successfully grown on tubular ceramic membranes using the catalytic chemical vapor deposition (CCVD) method. CNTs were synthesized at 650°C for 3-6 h under a 120 mL min(-1) flow of C2H6 on ceramic membranes impregnated with iron salt. The synthesis procedure was beforehand optimized in terms of catalyst amount, impregnation duration and reaction temperature, using small pieces of tubular ceramic membranes. The yield, size and structure of the CNTs produced were characterized using thermogravimetric analysis and microscopic imaging techniques. Afterwards, preliminary filtration tests with alginate and phenol were performed on two modified tubular membranes. The results indicate that the addition of CNTs on the membrane material increased the permeability of ceramic membrane and its ability to reject alginate and adsorb phenol, yet decreased its fouling resistance. PMID:26465312

  16. Tubular dense perovskite type membranes. Preparation, sealing, and oxygen permeation properties

    SciTech Connect

    Li, S.; Qi, H.; Xu, N.; Shi, J.

    1999-12-01

    Tubular dense perovskite type membranes were prepared by isostatic pressing and plastic extrusion. The resulting tubular La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3{minus}{delta}} perovskite type membrane prepared by plastic extrusion (designated as PE-LSCF) has a lower density and oxygen permeation flux compared with that prepared by isostatic pressing (designated as IP-LSCF). A ceramic binder developed by the research center provided reliable sealing for the tubular dense membrane at high temperature. The oxygen permeation flux increases with increasing temperature, and the value is about 0.13 cm{sup 3}/cm{sup 2} min (STP) at 1,123 K. The activation energy for oxygen permeation is 168 kJ/mol at the temperature range of 1,073--1,173. X-ray diffraction analysis for the membranes over 110 h of operation indicated that SrSO{sub 4}, CoSO{sub 4}, SrO, Co{sub 2}O{sub 3}, and La{sub 2}O{sub 3} were formed on the surfaces of the tubular membrane, especially for the tubular PE-LSCF membrane, because of interaction with trace SO{sub 2} in the air and the helium and segregation of surface elements.

  17. Microbial alkaloid staurosporine induces formation of nanometer-wide membrane tubular extensions (cytonemes, membrane tethers) in human neutrophils

    PubMed Central

    Stadnichuk, Vladimir; Molotkovsky, Julian G; Romanova, Julia M; Sud’ina, Galina F; Klein, Thomas

    2010-01-01

    In the present work, we demonstrate that microbial alkaloid staurosporine (STS) and Ro 31-8220, structurally related to STS protein kinase C inhibitor, caused development of membrane tubular extensions in human neutrophils upon adhesion to fibronectin-coated substrata. STS-induced tubular extensions interconnected neutrophils in a network and bound serum-opsonized bacteria Salmonella enterica serovar Typhimurium. The diameter of STS-induced extensions varied in the range 160–200 nm. The extensions were filled with cytoplasm and covered with membrane, as they included fluorescent cytoplasmic and lipid dyes. Neither protein kinase C inhibitors H-7 and bisindolylmaleimide VII, nor tyrosine protein kinase inhibitors tyrphostin AG 82 and genistein caused such extensions formation. Supposedly, STS induces membrane tubular extension formation promoting actin cytoskeleton depolymerization or affecting NO synthesis. PMID:20009568

  18. [The photoluminescence and absorption properties of Co/AAO nano-array composites].

    PubMed

    Li, Shou-Yi; Wang, Cheng-Wei; Li, Yan; Wang, Jian; Ma, Bao-Hong

    2008-03-01

    Ordered Co/AAO nano-array structures were fabricated by alternating current (AC) electrodeposition method within the cylindrical pores of anodic aluminum oxide (AAO) template prepared in oxalic acid electrolyte. The photoluminescence (PL) emission and photoabsorption of AAO templates and Co/AAO nano-array structures were investigated respectively. The results show that a marked photoluminescence band of AAO membranes occurs in the wavelength range of 350-550 nm and their PL peak position is at 395 nm. And with the increase in the deposition amount of Co nanoparticles, the PL intensity of Co/AAO nano-array structures decreases gradually, and their peak positions of the PL are invariable (395 nm). Meanwhile the absorption edges of Co/AAO show a larger redshift, and the largest shift from the near ultraviolet to the infrared exceeds 380 nm. The above phenomena caused by Co nano-particles in Co/AAO composite were analyzed. PMID:18536402

  19. The More the Tubular: Dynamic Bundling of Actin Filaments for Membrane Tube Formation

    PubMed Central

    Weichsel, Julian; Geissler, Phillip L.

    2016-01-01

    Tubular protrusions are a common feature of living cells, arising from polymerization of stiff protein filaments against a comparably soft membrane. Although this process involves many accessory proteins in cells, in vitro experiments indicate that similar tube-like structures can emerge without them, through spontaneous bundling of filaments mediated by the membrane. Using theory and simulation of physical models, we have elaborated how nonequilibrium fluctuations in growth kinetics and membrane shape can yield such protrusions. Enabled by a new grand canonical Monte Carlo method for membrane simulation, our work reveals a cascade of dynamical transitions from individually polymerizing filaments to highly cooperatively growing bundles as a dynamical bottleneck to tube formation. Filament network organization as well as adhesion points to the membrane, which bias filament bending and constrain membrane height fluctuations, screen the effective attractive interactions between filaments, significantly delaying bundling and tube formation. PMID:27384915

  20. The More the Tubular: Dynamic Bundling of Actin Filaments for Membrane Tube Formation.

    PubMed

    Weichsel, Julian; Geissler, Phillip L

    2016-07-01

    Tubular protrusions are a common feature of living cells, arising from polymerization of stiff protein filaments against a comparably soft membrane. Although this process involves many accessory proteins in cells, in vitro experiments indicate that similar tube-like structures can emerge without them, through spontaneous bundling of filaments mediated by the membrane. Using theory and simulation of physical models, we have elaborated how nonequilibrium fluctuations in growth kinetics and membrane shape can yield such protrusions. Enabled by a new grand canonical Monte Carlo method for membrane simulation, our work reveals a cascade of dynamical transitions from individually polymerizing filaments to highly cooperatively growing bundles as a dynamical bottleneck to tube formation. Filament network organization as well as adhesion points to the membrane, which bias filament bending and constrain membrane height fluctuations, screen the effective attractive interactions between filaments, significantly delaying bundling and tube formation. PMID:27384915

  1. Hydrogen transport through tubular membranes of palladium-coated tantalum and niobium

    SciTech Connect

    Buxbaum, R.E.; Kinney, A.B.

    1996-02-01

    Palladium-based membranes have been used for decades in hydrogen extraction because of their high permeability and good surface properties and because palladium, like all metals, is 100% selective for hydrogen transport. The authors describe experiments with hydrogen-extraction membranes made of palladium-coated niobium and tantalum heat-exchanger tubers. The cost was about $45/ft of 3/8 inch tubular membrane, and the fluxes were as high as 0.001 47 mol/m{sup 2} s Pa{sup 1/2} at 420 C. The main transport resistance is in the refractory metal substrate. Durability tests showed a 15% reduction in flux for 31 days of continuous membrane operation. Assuming durability is maintained for at least 1 year, this price and flux should allow competitive application for hydrogen recovery in petrochemical plants and for membrane reactors.

  2. Nonlinear Sorting, Curvature Generation, and Crowding of Endophilin N-BAR on Tubular Membranes

    PubMed Central

    Zhu, Chen; Das, Sovan L.; Baumgart, Tobias

    2012-01-01

    The curvature of biological membranes is controlled by membrane-bound proteins. For example, during endocytosis, the sorting of membrane components, vesicle budding, and fission from the plasma membrane are mediated by adaptor and accessory proteins. Endophilin is a peripherally binding membrane protein that functions as an endocytic accessory protein. Endophilin's membrane tubulation capacity is well known. However, to understand the thermodynamic and mechanical aspects of endophilin function, experimental measurements need to be compared to quantitative theoretical models. We present measurements of curvature sorting and curvature generation of the endophilin A1 N-BAR domain on tubular membranes pulled from giant unilamellar vesicles. At low concentration, endophilin functions primarily as a membrane curvature sensor; at high concentrations, it also generates curvature. We determine the spontaneous curvature induced by endophilin and observe sigmoidal curvature/composition coupling isotherms that saturate at high membrane tensions and protein solution concentrations. The observation of saturation is supported by a strong dependence of lateral diffusion coefficients on protein density on the tether membrane. We develop a nonlinear curvature/composition coupling model that captures our experimental observations. Our model predicts a curvature-induced phase transition among two states with varying protein density and membrane curvature. This transition could act as a switch during endocytosis. PMID:22768939

  3. Transport characteristics of L-citrulline in renal apical membrane of proximal tubular cells.

    PubMed

    Mitsuoka, Keisuke; Shirasaka, Yoshiyuki; Fukushi, Akimasa; Sato, Masanobu; Nakamura, Toshimichi; Nakanishi, Takeo; Tamai, Ikumi

    2009-04-01

    L-Citrulline has diagnostic potential for renal function, because its plasma concentration increases with the progression of renal failure. Although L-citrulline extracted by glomerular filtration in kidney is mostly reabsorbed, the mechanism involved is not clearly understood. The present study was designed to characterize L-citrulline transport across the apical membranes of renal epithelial tubular cells, using primary-cultured rat renal proximal tubular cells, as well as the human kidney proximal tubular cell line HK-2. L-Citrulline was transported in a Na(+)-dependent manner from the apical side of both cell types cultured on permeable supports with a microporous membrane. Kinetic analysis indicated that the transport involves two distinct Na(+)-dependent saturable systems and one Na(+)-independent saturable system in HK-2 cells. The uptake was competitively inhibited by neutral and cationic, but not anionic amino acids. Relatively large cationic and anionic compounds inhibited the uptake, but smaller ones did not. In HK-2 cells, mRNA expression of SLC6A19 and SLC7A9, which encode B(0)AT1 and b(0,+)AT, respectively, was detected by RT-PCR. In addition, L-citrulline transport was significantly decreased in HK-2 cells in which either SLC6A19 or SLC7A9 was silenced. Hence, these results suggest that amino acid transporters B(0)AT1 and b(0,+)AT are involved in the reabsorption of L-citrulline in the kidney, at least in part, by mediating the apical membrane transport of L-citrulline in renal tubule cells. PMID:19322909

  4. Natural clinoptilolite composite membranes on tubular stainless steel supports for water softening.

    PubMed

    Adamaref, Solmaz; An, Weizhu; Jarligo, Maria Ophelia; Kuznicki, Tetyana; Kuznicki, Steven M

    2014-01-01

    Disk membranes generated from high-purity natural clinoptilolite mineral rock have shown promising water desalination and de-oiling performance. In order to scale up production of these types of membranes for industrial wastewater treatment applications, a coating strategy was devised. A composite mixture of natural clinoptilolite from St. Cloud (Winston, NM, USA) and aluminum phosphate was deposited on the inner surface of porous stainless steel tubes by the slip casting technique. The commercial porous stainless steel tubes were pre-coated with a TiO2 layer of about 10 μm. Phase composition and morphology of the coating materials were investigated using X-ray diffraction and scanning electron microscopy. Water softening performance of the fabricated membranes was evaluated using Edmonton (Alberta, Canada) municipal tap water as feed source. Preliminary experimental results show a high water flux of 7.7 kg/(m(2) h) and 75% reduction of hardness and conductivity in a once-through membrane process at 95 °C and feed pressure of 780 kPa. These results show that natural zeolite coated, stainless steel tubular membranes have high potential for large-scale purification of oil sands steam-assisted gravity drainage water at high temperature and pressure requirements. PMID:25353948

  5. Investigation of H2S separation from H2S/CH4 mixtures using functionalized and non-functionalized vertically aligned carbon nanotube membranes

    NASA Astrophysics Data System (ADS)

    Gilani, Neda; Towfighi, Jafar; Rashidi, Alimorad; Mohammadi, Toraj; Omidkhah, Mohammad Reza; Sadeghian, Ahmad

    2013-04-01

    Separation of H2S from binary mixtures of H2S/CH4 using vertically aligned carbon nanotube membranes fabricated in anodic aluminum oxide (AAO) template was studied experimentally. Carbon nanotubes (CNTs) were grown in five AAO templates with different pore diameters using chemical vapor deposition, and CNT/AAO membranes with tubular carbon nanotube structure and open caps were selected for separation of H2S. For this, two tubular CNT/AAO membranes were fabricated with the CNT inner diameters of 23 and 8 nm. It was found that permeability and selectivity of the membrane with inner diameter of 23 nm for CNT were independent of upstream feed pressure and H2S feed concentration unlike that of CNT having an inner diameter of 8 nm. Selectivity of these membranes for separation of H2S was obtained in the ranges of 1.36-1.58 and 2.11-2.86, for CNTs with internal diameters of 23 and 8 nm, respectively. In order to enhance the separation of H2S from H2S/CH4 mixtures, dodecylamine was used to functionalize the CNT/AAO membrane with higher selectivity. The results showed that for amido-functionalized membrane, both upstream feed pressure and H2S partial pressure in the feed significantly increased H2S permeability, and selectivity for H2S being in the range of 3.0-5.57 respectively.

  6. Tubular lipid membranes pulled from vesicles: Dependence of system equilibrium on lipid bilayer curvature

    NASA Astrophysics Data System (ADS)

    Golushko, I. Yu.; Rochal, S. B.

    2016-01-01

    Conditions of joint equilibrium and stability are derived for a spherical lipid vesicle and a tubular lipid membrane (TLM) pulled from this vesicle. The obtained equations establish relationships between the geometric and physical characteristics of the system and the external parameters, which have been found to be controllable in recent experiments. In particular, the proposed theory shows that, in addition to the pressure difference between internal and external regions of the system, the variable spontaneous average curvature of the lipid bilayer (forming the TLM) also influences the stability of the lipid tube. The conditions for stability of the cylindrical phase of TLMs after switching off the external force that initially formed the TLM from a vesicle are discussed. The loss of system stability under the action of a small axial force compressing the TLM is considered.

  7. Helical image reconstruction of the outward-open human erythrocyte band 3 membrane domain in tubular crystals.

    PubMed

    Yamaguchi, Tomohiro; Fujii, Takashi; Abe, Yoshito; Hirai, Teruhisa; Kang, Dongchon; Namba, Keiichi; Hamasaki, Naotaka; Mitsuoka, Kaoru

    2010-03-01

    The C-terminal membrane domain of erythrocyte band 3 functions as an anion exchanger. Here, we report the three-dimensional (3D) structure of the membrane domain in an inhibitor-stabilized, outward-open conformation at 18A resolution. Unstained, frozen-hydrated tubular crystals containing the membrane domain of band 3 purified from human red blood cells (hB3MD) were examined using cryo-electron microscopy and iterative helical real-space reconstruction (IHRSR). The 3D image reconstruction of the tubular crystals showed the molecular packing of hB3MD dimers with dimensions of 60 x 110 A in the membrane plane and a thickness of 70A across the membrane. Immunoelectron microscopy and carboxyl-terminal digestion demonstrated that the intracellular surface of hB3MD was exposed on the outer surface of the tubular crystal. A 3D density map revealed that hB3MD consists of at least two subdomains and that the outward-open form is characterized by a large hollow area on the extracellular surface and continuous density on the intracellular surface. PMID:20005958

  8. The macula densa tubular basement membrane: a unique plaque of basement membrane specialization.

    PubMed

    Bonsib, S M

    1986-01-01

    The inner (luminal) surface of the macula densa (MD) basement membrane (BM) was exposed by solubilization of the overlying epithelium permitting examination of its structural features by scanning electron microscopy (SEM). Nineteen macula densa BM were identified in five autopsy kidneys and seven renal biopsies by this SEM technique. The MD BM consists of an oval plaque of specialized BM, restricted to the glomerular hilum and arteriolar aspect of the thick ascending limb of Henle. It contains haphazardly oriented shallow tunnels, slender pleats, and bridges of BM which do not resemble any other nephron BM examined by this technique. The MD BM, critically located between MD and lacis cells appears to firmly anchor the MD to the juxtaglomerular apparatus and may amplify the extent of interaction between lacis cell processes or lacis cell interstitial space and MD cell processes. PMID:3453363

  9. Enhancement of permeate flux by gas slugs for crossflow ultrafiltration in tubular membrane module

    SciTech Connect

    Cheng, T.W.; Yeh, H.M.; Gau, C.T.

    1998-11-01

    Flux enhancements by gas slugs for dextran T500 solutions ultrafiltrated in a ZrO{sub 2}/carbon tubular membrane module were measured and are discussed for various resistances of the concentration boundary layer. These resistances are functions of the liquid velocity, the transmembrane pressure, and the feed concentration in the liquid-phase ultrafiltration. When the boundary layer resistance is low, the flux enhancement by gas slugs is limited. For a liquid ultrafiltration system with a severe concentration polarization, or operated in conditions of low liquid velocity, high transmembrane pressure, and high feed concentration, flux enhancement by gas slugs is very significant if the gas velocity exceeds a certain threshold. This threshold gas velocity depends on the extent of the concentration polarization in the single liquid-phase ultrafiltration system. It is concluded that the same permeate flux obtained in single liquid-phase ultrafiltration with a higher crossflow velocity can also be achieved with a lower liquid velocity by introducing gas slug of moderate velocity, and lead to reduced energy consumption.

  10. [Flow field test on the tangential section of polypropylene tubular membrane module annular gap in rotating linear tangential flow].

    PubMed

    Wang, Chengduan; Chen, Wenmei; Li, Jianming; Jiang, Guangming

    2002-07-01

    A new type of polypropylene tubular membrane apparatus of rotating cross flow was designed to study experimentally the flow field characteristics of the tangential section of the membrane annular gap. The authors designed rotary linear tangential flow tubular membrane separator and its test system for the first time. Through the system, the flow field of rotary linear tangential flow with the advanced Particle Image Velocimetry (PIV) was tested for the first time. A lot of streamlines and vorticity maps of the tangential section of separator in different operation conditions were obtained. The velocity distribution characteristics were analyzed quantitatively: 1. At non-vortex area, no matter how the operation parameters change, the velocity near to rotary tangential flow entrance was higher than the velocity far from entrance at the same radial coordinates. At vortex area, generally the flow velocity of inner vortex was lower than the outer vortex. At the vortex center, the velocity was lowest, the tangential velocity were equal to zero generally. At the vortex center zone, the tangential velocity was less than the axial velocity. 2. Under test operations, the tangential velocity and axial velocity of vortices borders are 1-2 times of average axial velocity of membrane module annular gap. The maximum tangential velocity and axial velocity of ellipse vortices were 2-6 times of average axial velocity of membrane module annular gap. 3. The vortices that are formed on the tangential section, there existed mass transfer between inner and outer parts of fluid. Much fluid of outer vortices got into the inner ones, which was able to prevent membrane tube from particles blocking up very soon. PMID:12371104

  11. Tubular ceramic-supported sol-gel silica-based membranes for flue gas carbon dioxide capture and sequestration.

    SciTech Connect

    Tsai, C. Y.; Xomeritakis, George K.; Brinker, C. Jeffrey; Jiang, Ying-Bing

    2009-03-01

    Pure, amine-derivatized and nickel-doped sol-gel silica membranes have been developed on tubular Membralox-type commercial ceramic supports for the purpose of carbon dioxide separation from nitrogen under coal-fired power plant flue gas conditions. An extensive synthetic and permeation test study was carried out in order to optimize membrane CO{sub 2} permeance, CO{sub 2}:N{sub 2} separation factor and resistance against densification. Pure silica membranes prepared under optimized conditions exhibited an attractive combination of CO{sub 2} permeance of 2.0 MPU (1 MPU = 1 cm{sup 3}(STP) {center_dot} cm{sup -2} min{sup -1} atm{sup -1}) and CO{sub 2}:N{sub 2} separation factor of 80 with a dry 10:90 (v/v) CO{sub 2}:N{sub 2} feed at 25 C. However, these membranes exhibited flux decline phenomena under prolonged exposure to humidified feeds, especially in the presence of trace SO{sub 2} gas in the feed. Doping the membranes with nickel (II) nitrate salt was effective in retarding densification, as manifested by combined higher permeance and higher separation factor of the doped membrane compared to the pure (undoped) silica membrane after 168 hours exposure to simulated flue gas conditions.

  12. A colorimetric sensor based on anodized aluminum oxide (AAO) substrate for the detection of nitroaromatics.

    SciTech Connect

    Liu, Y.; Wang, H. H.; Indacochea, J. E.; Wang, M. L.

    2011-12-15

    Simple and low cost colorimetric sensors for explosives detection were explored and developed. Anodized aluminum oxide (AAO) with large surface area through its porous structure and light background color was utilized as the substrate for colorimetric sensors. Fabricated thin AAO films with thickness less than {approx} 500 nm allowed us to observe interference colors which were used as the background color for colorimetric detection. AAO thin films with various thickness and pore-to-pore distance were prepared through anodizing aluminum foils at different voltages and times in dilute sulfuric acid. Various interference colors were observed on these samples due to their difference in structures. Accordingly, suitable anodization conditions that produce AAO samples with desired light background colors for optical applications were obtained. Thin film interference model was applied to analyze the UV-vis reflectance spectra and to estimate the thickness of the AAO membranes. We found that the thickness of produced AAO films increased linearly with anodization time in sulfuric acid. In addition, the growth rate was higher for AAO anodized using higher voltages. The thin film interference formulism was further validated with a well established layer by layer deposition technique. Coating poly(styrene sulfonate) sodium salt (PSS) and poly(allylamine hydrochloride) (PAH) layer by layer on AAO thin film consistently shifted its surface color toward red due to the increase in thickness. The red shift of UV-vis reflectance was correlated quantitatively to the number of layers been assembled. This sensitive red shift due to molecular attachment (increase in thickness) on AAO substrate was applied toward nitroaromatics detection. Aminopropyltrimethoxysilane (APTS) which can be attached onto AAO nanowells covalently through silanization and attract TNT molecules was coated and applied for TNT detection. UV-vis spectra of AAO with APTS shifted to the longer wavelength side due to

  13. ARSENIC DETERMINATION IN SALINE WATERS UTILIZING A TUBULAR MEMBRANE AS A GAS-LIQUID SEPATRATOR FOR HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    EPA Science Inventory

    A tubular silicone rubber membrane is evaluated as a gas-liquid separator for the determination of arsenic in saline waters via HG-ICP-MS. The system was optimized in terms of NaBH and HCI concentrations. The intermediate gas and carrier gas were optimized in terms of sensitiity ...

  14. Three-Dimensional Visualization of the Tubular-Lamellar Transformation of the Internal Plastid Membrane Network during Runner Bean Chloroplast Biogenesis.

    PubMed

    Kowalewska, Łucja; Mazur, Radosław; Suski, Szymon; Garstka, Maciej; Mostowska, Agnieszka

    2016-04-01

    Chloroplast biogenesis is a complex process that is integrated with plant development, leading to fully differentiated and functionally mature plastids. In this work, we used electron tomography and confocal microscopy to reconstruct the process of structural membrane transformation during the etioplast-to-chloroplast transition in runner bean (Phaseolus coccineus). During chloroplast development, the regular tubular network of paracrystalline prolamellar bodies (PLBs) and the flattened porous membranes of prothylakoids develop into the chloroplast thylakoids. Three-dimensional reconstruction is required to provide us with a more complete understanding of this transformation. We provide spatial models of the bean chloroplast biogenesis that allow such reconstruction of the internal membranes of the developing chloroplast and visualize the transformation from the tubular arrangement to the linear system of parallel lamellae. We prove that the tubular structure of the PLB transforms directly to flat slats, without dispersion to vesicles. We demonstrate that the grana/stroma thylakoid connections have a helical character starting from the early stages of appressed membrane formation. Moreover, we point out the importance of particular chlorophyll-protein complex components in the membrane stacking during the biogenesis. The main stages of chloroplast internal membrane biogenesis are presented in a movie that shows the time development of the chloroplast biogenesis as a dynamic model of this process. PMID:27002023

  15. Analysis of Tubular Membrane Networks in Cardiac Myocytes from Atria and Ventricles

    PubMed Central

    Kohl, Tobias; Lehnart, Stephan E.

    2014-01-01

    In cardiac myocytes a complex network of membrane tubules - the transverse-axial tubule system (TATS) - controls deep intracellular signaling functions. While the outer surface membrane and associated TATS membrane components appear to be continuous, there are substantial differences in lipid and protein content. In ventricular myocytes (VMs), certain TATS components are highly abundant contributing to rectilinear tubule networks and regular branching 3D architectures. It is thought that peripheral TATS components propagate action potentials from the cell surface to thousands of remote intracellular sarcoendoplasmic reticulum (SER) membrane contact domains, thereby activating intracellular Ca2+ release units (CRUs). In contrast to VMs, the organization and functional role of TATS membranes in atrial myocytes (AMs) is significantly different and much less understood. Taken together, quantitative structural characterization of TATS membrane networks in healthy and diseased myocytes is an essential prerequisite towards better understanding of functional plasticity and pathophysiological reorganization. Here, we present a strategic combination of protocols for direct quantitative analysis of TATS membrane networks in living VMs and AMs. For this, we accompany primary cell isolations of mouse VMs and/or AMs with critical quality control steps and direct membrane staining protocols for fluorescence imaging of TATS membranes. Using an optimized workflow for confocal or superresolution TATS image processing, binarized and skeletonized data are generated for quantitative analysis of the TATS network and its components. Unlike previously published indirect regional aggregate image analysis strategies, our protocols enable direct characterization of specific components and derive complex physiological properties of TATS membrane networks in living myocytes with high throughput and open access software tools. In summary, the combined protocol strategy can be readily applied

  16. ER stress and basement membrane defects combine to cause glomerular and tubular renal disease resulting from Col4a1 mutations in mice

    PubMed Central

    Jones, Frances E.; Bailey, Matthew A.; Murray, Lydia S.; Lu, Yinhui; McNeilly, Sarah; Schlötzer-Schrehardt, Ursula; Lennon, Rachel; Sado, Yoshikazu; Brownstein, David G.; Mullins, John J.; Kadler, Karl E.; Van Agtmael, Tom

    2016-01-01

    ABSTRACT Collagen IV is a major component of basement membranes, and mutations in COL4A1, which encodes collagen IV alpha chain 1, cause a multisystemic disease encompassing cerebrovascular, eye and kidney defects. However, COL4A1 renal disease remains poorly characterized and its pathomolecular mechanisms are unknown. We show that Col4a1 mutations in mice cause hypotension and renal disease, including proteinuria and defects in Bowman's capsule and the glomerular basement membrane, indicating a role for Col4a1 in glomerular filtration. Impaired sodium reabsorption in the loop of Henle and distal nephron despite elevated aldosterone levels indicates that tubular defects contribute to the hypotension, highlighting a novel role for the basement membrane in vascular homeostasis by modulation of the tubular response to aldosterone. Col4a1 mutations also cause diabetes insipidus, whereby the tubular defects lead to polyuria associated with medullary atrophy and a subsequent reduction in the ability to upregulate aquaporin 2 and concentrate urine. Moreover, haematuria, haemorrhage and vascular basement membrane defects confirm an important vascular component. Interestingly, although structural and compositional basement membrane defects occurred in the glomerulus and Bowman's capsule, no tubular basement membrane defects were detected. By contrast, medullary atrophy was associated with chronic ER stress, providing evidence for cell-type-dependent molecular mechanisms of Col4a1 mutations. These data show that both basement membrane defects and ER stress contribute to Col4a1 renal disease, which has important implications for the development of treatment strategies for collagenopathies. PMID:26839400

  17. Gaia15aao is ASASSN-15bk

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, L.

    2015-02-01

    The supernova Gaia15aao reported in ATEL #7014 was first discovered by the ASAS-SN group as ASASSN-15bk on 2015-01-19.62 (ATEL #6979) and classified spectroscopically (ATEL #6988) on 2015-01-25. Gaia observation from 2015-01-12 preceded ASASSN's detection by about a week, however, the actual discovery in the Gaia data happened on 2015-01-26.

  18. Preparation and characterization of micro-cell membrane chromatographic column with silica-based porous layer open tubular capillary as cellular membrane carrier.

    PubMed

    Zhang, Fugeng; Zhao, Xinchao; Xu, Bei; Cheng, Shuai; Tang, Cheng; Duan, Hongquan; Xiao, Xuefeng; Du, Wuxun; Xu, Liang

    2016-04-01

    Cell membrane chromatography (CMC) is a powerful tool to study membrane protein interactions and to screen active compounds extracted from natural products. Unfortunately, a large amount of cells are typically required for column preparation in order to carry out analyses in an efficient manner. Micro-CMC (mCMC) has recently been developed by using a silica capillary as a membrane carrier. However, a reduced retention of analytes is generally associated with mCMC mostly due to a low ligand (cellular membrane) capacity. To solve this common problem, in this work a silica-based porous layer open tubular (PLOT) capillary was fabricated and, to the best of our knowledge, for the first time applied to mCMC. The mCMC column was prepared by physical adsorption of rabbit red blood cell (rRBC) membranes onto the inner surface of the PLOT capillary. The effects of the PLOT capillaries fabricated by different feed compositions, on the immobilization amount of cellular membranes (represented by the fluorescence intensity of the capillary immobilized with fluorescein isothiocyanate isomer-labeled cellular membranes) and on the dynamic binding capacity (DBC) of verapamil (VP, a widely used calcium antagonist which specific interacts with L-type calcium channel proteins located on cellular membrane of rRBC) have been systematically investigated. The fluorescence intensity of the mCMC column when combined with the PLOT capillary was found to be more than five times higher than the intensity using a bare capillary. This intriguing result indicates that the PLOT capillary exhibits a higher cellular membrane capacity. The DBC of VP in the PLOT column was found to be more than nine times higher than that in the bare capillary. An rRBC/CMC column was also prepared for comparative studies. As a result, mCMC provides similar chromatographic retention factors and stability with common CMC; however, the cellular membrane consumption for mCMC was found to be more than 460 times lower than

  19. Experimental and theoretical analysis of tubular membrane aeration for Mammalian cell bioreactors.

    PubMed

    Qi, Hanshi N; Goudar, Chetan T; Michaels, James D; Henzler, Hans-Jugen; Jovanovic, Goran N; Konstantinov, Konstantin B

    2003-01-01

    A combination of experimental and theoretical approaches was used to characterize the dynamics of oxygen transfer in a membrane-aerated bioreactor. Pressure profiles along the length of the membrane at varying entrance and exit pressures were determined by actual experimental measurements, unlike most previous studies that have relied solely on theoretical descriptions of the pressure profile in the tubing. The mass transfer coefficient, k(L)a, was also determined under these conditions and was found to be essentially independent of tubing exit pressure. Measurement of the tubing pressure profile coupled with estimation of k(L)a allowed for computation of the oxygen transfer rate (OTR) along the length of the tubing. A mathematical model that incorporated friction pressure loss and losses due to tubing bending was developed to describe the pressure and hence OTR characteristics of membrane-aerated systems. The applicability of the model was verified by testing it on experimentally measured pressure data, and in all cases the model accurately described experimental data. When tubing properties are known, the mathematical model presented in this study allows for a priori estimation of OTR profiles along the length of the tubing. This information is vital for optimal design and scale-up of membrane-aerated bioreactors for mammalian cell culture. PMID:12892480

  20. Rejection of organic micro-pollutants from water by a tubular, hydrophilic pervaporative membrane designed for irrigation applications.

    PubMed

    Sule, May N; Templeton, Michael R; Bond, Tom

    2016-01-01

    The links between chemical properties, including those relating to molecular size, solubility, hydrophobicity and vapour pressure, and rejection of model aromatic micro-pollutants by a tubular, hydrophilic polymer pervaporation membrane designed for irrigation applications were investigated. Open air experiments were conducted at room temperature for individual solutions of fluorene, naphthalene, phenol, 1,2-dichlorobenzene, 1,2-diethylbenzene and 2-phenoxyethanol. Percentage rejection generally increased with increased molecular size for the model micro-pollutants (47-86%). Molecular weight and log Kow had the strongest positive relationships with rejection, as demonstrated by respective correlation coefficients of r = 0.898 and 0.824. Rejection was also strongly negatively correlated with aqueous solubility and H-bond δ. However, properties which relate to vapour phase concentrations of the micro-pollutants were not well correlated with rejection. Thus, physicochemical separation processes, rather than vapour pressure, drive removal of aromatic contaminants by the investigated pervaporation tube. This expanded knowledge could be utilized in considering practical applications of pervaporative irrigation systems for treating organic-contaminated waters such as oilfield-produced waters. PMID:26585567

  1. The delayed rectifier potassium conductance in the sarcolemma and the transverse tubular system membranes of mammalian skeletal muscle fibers

    PubMed Central

    DiFranco, Marino; Quinonez, Marbella

    2012-01-01

    A two-microelectrode voltage clamp and optical measurements of membrane potential changes at the transverse tubular system (TTS) were used to characterize delayed rectifier K currents (IKV) in murine muscle fibers stained with the potentiometric dye di-8-ANEPPS. In intact fibers, IKV displays the canonical hallmarks of KV channels: voltage-dependent delayed activation and decay in time. The voltage dependence of the peak conductance (gKV) was only accounted for by double Boltzmann fits, suggesting at least two channel contributions to IKV. Osmotically treated fibers showed significant disconnection of the TTS and displayed smaller IKV, but with similar voltage dependence and time decays to intact fibers. This suggests that inactivation may be responsible for most of the decay in IKV records. A two-channel model that faithfully simulates IKV records in osmotically treated fibers comprises a low threshold and steeply voltage-dependent channel (channel A), which contributes ∼31% of gKV, and a more abundant high threshold channel (channel B), with shallower voltage dependence. Significant expression of the IKV1.4 and IKV3.4 channels was demonstrated by immunoblotting. Rectangular depolarizing pulses elicited step-like di-8-ANEPPS transients in intact fibers rendered electrically passive. In contrast, activation of IKV resulted in time- and voltage-dependent attenuations in optical transients that coincided in time with the peaks of IKV records. Normalized peak attenuations showed the same voltage dependence as peak IKV plots. A radial cable model including channels A and B and K diffusion in the TTS was used to simulate IKV and average TTS voltage changes. Model predictions and experimental data were compared to determine what fraction of gKV in the TTS accounted simultaneously for the electrical and optical data. Best predictions suggest that KV channels are approximately equally distributed in the sarcolemma and TTS membranes; under these conditions, >70% of IKV

  2. The Na conductance in the sarcolemma and the transverse tubular system membranes of mammalian skeletal muscle fibers.

    PubMed

    DiFranco, Marino; Vergara, Julio L

    2011-10-01

    Na (and Li) currents and fluorescence transients were recorded simultaneously under voltage-clamp conditions from mouse flexor digitorum brevis fibers stained with the potentiometric dye di-8-ANEPPS to investigate the distribution of Na channels between the surface and transverse tubular system (TTS) membranes. In fibers rendered electrically passive, voltage pulses resulted in step-like fluorescence changes that were used to calibrate the dye response. The effects of Na channel activation on the TTS voltage were investigated using Li, instead of Na, because di-8-ANEPPS transients show anomalies in the presence of the latter. Na and Li inward currents (I(Na), I(Li); using half of the physiological ion concentration) showed very steep voltage dependences, with no reversal for depolarizations beyond the calculated equilibrium potential, suggesting that most of the current originates from a noncontrolled membrane compartment. Maximum peak I(Li) was ∼ 30% smaller than for I(Na), suggesting a Li-blocking effect. I(Li) activation resulted in the appearance of overshoots in otherwise step-like di-8-ANEPPS transients. Overshoots had comparable durations and voltage dependence as those of I(Li). Simultaneously measured maximal overshoot and peak I(Li) were 54 ± 5% and 773 ± 53 µA/cm(2), respectively. Radial cable model simulations predicted the properties of I(Li) and di-8-ANEPPS transients when TTS access resistances of 10-20 Ω cm(2), and TTS-to-surface Na permeability density ratios in the range of 40:60 to 70:30, were used. Formamide-based osmotic shock resulted in incomplete detubulation. However, results from a subpopulation of treated fibers (low capacitance) provide confirmatory evidence that a significant proportion of I(Li), and the overshoot in the optical signals, arises from the TTS in normal fibers. The quantitative evaluation of the distribution of Na channels between the sarcolemma and the TTS membranes, as provided here, is crucial for the

  3. Flow injection analysis with tubular membrane ion-selective electrode and coated wires for buspirone hydrochloride.

    PubMed

    Abdel-Ghani, Nour; Issa, Yousry; Shoukry, Adel; Ahmed, Howayda

    2007-01-01

    New Plastic membrane ion-selective electrode for buspirone hydrochloride based on buspironium tetraphenylborate was prepared. The electrode exhibited mean slope of calibration graph of 58.4 mV per decade of BusCl concentration at 25 degrees C. The electrode can be used within the concentration range 6.3 x 10(-5) - 10(-2) M BusCl at a pH range of 2.5-7.0. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal temperature coefficient of the electrode, amounting to 0.00056 V degrees C(-1). The electrode showed a very good selectivity for BusCl with respect to a number of inorganic cations, sugars and amino acids. The electrode was applied to the potentiometric determination of the buspirone ion and its pharmaceutical preparation under batch and flow injection conditions. Also, buspirone was determined by conductimetric titrations. Graphite rod, copper and silver coated wire electrodes were prepared and characterized as sensors for the drug under investigation. PMID:17822267

  4. Carbon molecular sieve membranes on porous composite tubular supports for high performance gas separations

    DOE PAGESBeta

    Lee, Pyung -Soo; Bhave, Ramesh R.; Nam, Seung -Eun; Kim, Daejin

    2016-01-11

    Thin carbon molecular sieve membranes (<500 nm) were fabricated inside of long geometry (9 inch) of stainless steel tubes with all welded construction. Alumina intermediate layer on porous stainless steel tube support was used to reduce effective support pore size and to provide a more uniform surface roughness. Novolac phenolic resin solution was then coated on the inside of porous stainless steel tube by slip casting while their viscosities were controlled from 5 centipoises to 30 centipoises. Carbonization was carried out at 700 °C in which thermal stress was minimized and high quality carbon films were prepared. The highest separationmore » performance characteristics were obtained using 20 cP phenolic resin solutions. The fabricated CMSM showed good separation factor for He/N2 462, CO2/N2 97, and O2/N2 15.4. As the viscosity of polymer precursor solution was reduced from 20 cP to 15 cP, gas permeance values almost doubled with somewhat lower separation factor He/N2 156, CO2/N2 88, and O2/N2 7.7.« less

  5. Fabrication of nanowire network AAO and its application in SERS

    PubMed Central

    2013-01-01

    In this paper, nanowire network anodized aluminum oxide (AAO) was fabricated by just adding a simple film-eroding process after the production of porous AAO. After depositing 50 nm of Au onto the surface, nanowire network AAO can be used as ultrasensitive and high reproducibility surface-enhanced Raman scattering (SERS) substrate. The average Raman enhancement factor of the nanowire network AAO SERS substrate can reach 5.93 × 106, which is about 14% larger than that of commercial Klarite® substrates. Simultaneously, the relative standard deviations in the SERS intensities are limited to approximately 7%. All of the results indicate that our large-area low-cost high-performance nanowire structure AAO SERS substrates have a great advantage in chemical/biological sensing applications. PMID:24261342

  6. Surface heat shock protein 90 serves as a potential receptor for calcium oxalate crystal on apical membrane of renal tubular epithelial cells.

    PubMed

    Fong-Ngern, Kedsarin; Sueksakit, Kanyarat; Thongboonkerd, Visith

    2016-07-01

    Adhesion of calcium oxalate monohydrate (COM) crystals on renal tubular epithelial cells is a crucial step in kidney stone formation. Finding potential crystal receptors on the apical membrane of the cells may lead to a novel approach to prevent kidney stone disease. Our previous study identified a large number of crystal-binding proteins on the apical membrane of MDCK cells. However, their functional role as potential crystal receptors had not been validated. The present study aimed to address the potential role of heat shock protein 90 (HSP90) as a COM crystal receptor. The apical membrane was isolated from polarized MDCK cells by the peeling method and recovered proteins were incubated with COM crystals. Western blot analysis confirmed the presence of HSP90 in the apical membrane and the crystal-bound fraction. Immunofluorescence staining without permeabilization and laser-scanning confocal microscopy confirmed the surface HSP90 expression on the apical membrane of the intact cells. Crystal adhesion assay showed that blocking surface HSP90 by specific anti-HSP90 antibody and knockdown of HSP90 by small interfering RNA (siRNA) dramatically reduced crystal binding on the apical surface of MDCK cells (by approximately 1/2 and 2/3, respectively). Additionally, crystal internalization assay revealed the presence of HSP90 on the membrane of endocytic vesicle containing the internalized COM crystal. Moreover, pretreatment of MDCK cells with anti-HSP90 antibody significantly reduced crystal internalization (by approximately 1/3). Taken together, our data indicate that HSP90 serves as a potential receptor for COM crystals on the apical membrane of renal tubular epithelial cells and is involved in endocytosis/internalization of the crystals into the cells. PMID:27115409

  7. Fabrication of indium sulfide nanofibers via a hydrothermal method assisted by AAO template

    SciTech Connect

    Zhu Xiaoyi; Ma Junfeng . E-mail: majf@mail.ouc.edu.cn; Wang Yonggang; Tao Jiantao; Zhou Jun; Zhao Zhongqiang; Xie Lijin; Tian Hua

    2006-08-10

    {beta}-In{sub 2}S{sub 3} nanofibers were successfully synthesized via a hydrothermal method with AAO membrane as a template at 150 deg. C for 15 h. XRD patterns indicated the perfect crystallization of {beta}-In{sub 2}S{sub 3}. SEM images showed that the {beta}-In{sub 2}S{sub 3} nanofibers grew up from the channel ends of the AAO template. TEM images confirmed that the nanofibers had a high aspect ratio of ca. 40-50 and diameters of about 10 nm. The room temperature photoluminescence (PL) spectrum of the {beta}-In{sub 2}S{sub 3} nanofibers indicated its potential applications in light-emission devices.

  8. Performance and mechanisms for the removal of phthalates and pharmaceuticals from aqueous solution by graphene-containing ceramic composite tubular membrane coupled with the simultaneous electrocoagulation and electrofiltration process.

    PubMed

    Yang, Gordon C C; Chen, Ying-Chun; Yang, Hao-Xuan; Yen, Chia-Heng

    2016-07-01

    In this study, commonly detected emerging contaminants (ECs) in water, including di-n-butyl phthalate (DnBP), di(2-ethylhexyl) phthalate (DEHP), cephalexin (CLX), sulfamethoxazole (SMX) and caffeine (CAF), were selected as the target contaminants. A lab-prepared graphene-containing ceramic composite tubular membrane (TGCCM) coupled with the simultaneous electrocoagulation and electrofiltration process (EC/EF) in crossflow filtration mode was used to remove target contaminants in model solution. Meanwhile, a comparison of the removal efficiency was made among various tubular composite membranes reported, including carbon fibers/carbon/alumina composite tubular membrane (TCCACM), titania/alumina composite tubular membrane (TTACM) and alumina tubular membrane (TAM). The results of this study showed that the removal efficiencies for DnBP and DEHP were 99%, whereas 32-97% for cephalexin (CLX), sulfamethoxazole (SMX) and caffeine (CAF). In this work the mechanisms involved in removing target ECs were proposed and their roles in removing various ECs were also discussed. Further, two actual municipal wastewaters were treated to evaluate the applicability of the aforementioned treatment technology (i.e., TGCCM coupled with EC/EF) to various aqueous solutions in the real world. PMID:27131034

  9. The Software System for the AAO's HERMES Spectrograph

    NASA Astrophysics Data System (ADS)

    Shortridge, K.; Farrell, T.; Vuong, M.; Birchall, M.; Heald, R.

    2013-10-01

    The AAO's HERMES spectrograph will start operation in 2013. Its primary project will be a Galactic Archaeology survey that aims to reconstruct the early history of our Galaxy through precise measurements of the chemical abundances of one million stars. This paper describes some of the software aspects of the HERMES project: how it has evolved from the earlier AAO 2dF system, the extensive use of simulation for testing, the overall observing system, and the data reduction pipeline.

  10. MICAL-L1 is a tubular endosomal membrane hub that connects Rab35 and Arf6 with Rab8a

    PubMed Central

    Rahajeng, Juliati; Giridharan, Sai Srinivas Panapakkam; Cai, Bishuang; Naslavsky, Naava; Caplan, Steve

    2011-01-01

    Endocytosis is a conserved process across species in which cell surface receptors and lipids are internalized from the plasma membrane. Once internalized, receptors can either be degraded or recycled back to the plasma membrane. A variety of small GTP-binding proteins regulate receptor recycling. Despite our familiarity with many of the key regulatory proteins involved in this process, our understanding of the mode by which these proteins cooperate and the sequential manner in which they function remains limited. In this study, we identify two GTP-binding proteins as interaction partners of the endocytic regulatory protein MICAL-L1. First, we demonstrate that Rab35 is a MICAL-L1 binding partner in vivo. Over-expression of active Rab35 impairs the recruitment of MICAL-L1 to tubular recycling endosomes, whereas Rab35 depletion promotes enhanced MICAL-L1 localization to these structures. Moreover, we demonstrate that Arf6 forms a complex with MICAL-L1 and plays a role in its recruitment to tubular endosomes. Overall, our data suggest a model in which Rab35 is a critical upstream regulator of MICAL-L1 and Arf6, while both MICAL-L1 and Arf6 regulate Rab8a function. PMID:21951725

  11. Cell Adhesion and Growth on the Anodized Aluminum Oxide Membrane.

    PubMed

    Park, Jeong Su; Moon, Dalnim; Kim, Jin-Seok; Lee, Jin Seok

    2016-03-01

    Nanotopological cues are popular tools for in vivo investigation of the extracellular matrix (ECM) and cellular microenvironments. The ECM is composed of multiple components and generates a complex microenvironment. The development of accurate in vivo methods for the investigation of ECM are important for disease diagnosis and therapy, as well as for studies on cell behavior. Here, we fabricated anodized aluminum oxide (AAO) membranes using sulfuric and oxalic acid under controlled voltage and temperature. The membranes were designed to possess three different pore and interpore sizes, AAO-1, AAO-2, and AAO-3 membranes, respectively. These membranes were used as tools to investigate nanotopology-signal induced cell behavior. Cancerous cells, specifically, the OVCAR-8 cell-line, were cultured on porous AAO membranes and the effects of these membranes on cell shape, proliferation, and viability were studied. AAO-1 membranes bearing small sized pores were found to maintain the spreading shape of the cultured cells. Cells cultured on AAO-2 and AAO-3 membranes, bearing large pore-sized AAO membranes, changed shape from spreading to rounding. Furthermore, cellular area decreased when cells were cultured on all three AAO membranes that confirmed decreased levels of focal adhesion kinase (FAK). Additionally, OVCAR-8 cells exhibited increased proliferation on AAO membranes possessing various pore sizes, indicating the importance of the nanosurface structure in regulating cell behaviors, such as cell proliferation. Our results suggest that porous-AAO membranes induced nanosurface regulated cell behavior as focal adhesion altered the intracellular organization of the cytoskeleton. Our results may find potential applications as tools in in vivo cancer research studies. PMID:27280255

  12. Rapid Ca2+ flux through the transverse tubular membrane, activated by individual action potentials in mammalian skeletal muscle

    PubMed Central

    Launikonis, Bradley S; Stephenson, D George; Friedrich, Oliver

    2009-01-01

    Periods of low frequency stimulation are known to increase the net Ca2+ uptake in skeletal muscle but the mechanism responsible for this Ca2+ entry is not known. In this study a novel high-resolution fluorescence microscopy approach allowed the detection of an action potential-induced Ca2+ flux across the tubular (t-) system of rat extensor digitorum longus muscle fibres that appears to be responsible for the net uptake of Ca2+ in working muscle. Action potentials were triggered in the t-system of mechanically skinned fibres from rat by brief field stimulation and t-system [Ca2+] ([Ca2+]t-sys) and cytoplasmic [Ca2+] ([Ca2+]cyto) were simultaneously resolved on a confocal microscope. When initial [Ca2+]t-sys was ≥ 0.2 mm a Ca2+ flux from t-system to the cytoplasm was observed following a single action potential. The action potential-induced Ca2+ flux and associated t-system Ca2+ permeability decayed exponentially and displayed inactivation characteristics such that further Ca2+ entry across the t-system could not be observed after 2–3 action potentials at 10 Hz stimulation rate. When [Ca2+]t-sys was closer to 0.1 mm, a transient rise in [Ca2+]t-sys was observed almost concurrently with the increase in [Ca2+]cyto following the action potential. The change in direction of Ca2+ flux was consistent with changes in the direction of the driving force for Ca2+. This is the first demonstration of a rapid t-system Ca2+ flux associated with a single action potential in mammalian skeletal muscle. The properties of this channel are inconsistent with a flux through the L-type Ca2+ channel suggesting that an as yet unidentified t-system protein is conducting this current. This action potential-activated Ca2+ flux provides an explanation for the previously described Ca2+ entry and accumulation observed with prolonged, intermittent muscle activity. PMID:19332499

  13. Proximal renal tubular acidosis

    MedlinePlus

    Renal tubular acidosis - proximal; Type II RTA; RTA - proximal; Renal tubular acidosis type II ... by alkaline substances, mainly bicarbonate. Proximal renal tubular acidosis (Type II RTA) occurs when bicarbonate is not ...

  14. Cooperation of the ER-shaping proteins atlastin, lunapark, and reticulons to generate a tubular membrane network.

    PubMed

    Wang, Songyu; Tukachinsky, Hanna; Romano, Fabian B; Rapoport, Tom A

    2016-01-01

    In higher eukaryotes, the endoplasmic reticulum (ER) contains a network of membrane tubules, which transitions into sheets during mitosis. Network formation involves curvature-stabilizing proteins, including the reticulons (Rtns), as well as the membrane-fusing GTPase atlastin (ATL) and the lunapark protein (Lnp). Here, we have analyzed how these proteins cooperate. ATL is needed to not only form, but also maintain, the ER network. Maintenance requires a balance between ATL and Rtn, as too little ATL activity or too high Rtn4a concentrations cause ER fragmentation. Lnp only affects the abundance of three-way junctions and tubules. We suggest a model in which ATL-mediated fusion counteracts the instability of free tubule ends. ATL tethers and fuses tubules stabilized by the Rtns, and transiently sits in newly formed three-way junctions. Lnp subsequently moves into the junctional sheets and forms oligomers. Lnp is inactivated by mitotic phosphorylation, which contributes to the tubule-to-sheet conversion of the ER. PMID:27619977

  15. Erythropoietin protects the tubular basement membrane by promoting the bone marrow to release extracellular vesicles containing tPA-targeting miR-144.

    PubMed

    Zhou, Yang; Fang, Li; Yu, Yanting; Niu, Jing; Jiang, Lei; Cao, Hongdi; Sun, Qi; Zen, Ke; Dai, Chunsun; Yang, Junwei

    2016-01-01

    Renal fibrosis is an inevitable outcome of chronic kidney disease (CKD). Erythropoietin (EPO) has been recently reported to be able to mitigate renal fibrosis. The mechanism underlying the protective effect of EPO, however, remains elusive. In the present study, employing a mouse model of renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction (UUO), we demonstrated that EPO markedly reduced the disruption of the tubular basement membrane (TBM) through attenuating the activation of tissue plasminogen activator (tPA) and matrix metalloproteinase 9 (MMP9), the major matrix proteolytic network in the obstructed kidney. Instead of acting directly on tPA in the kidney, EPO strongly increased the level of circulating microRNA (miR)-144, which was delivered to the injured renal fibroblasts via extracellular vesicles (EVs) to target the tPA 3'-untranslated region and suppress tPA expression. The protective effect of EPO on mouse TBM was inhibited by miR-144 antagomir. Furthermore, in vitro results confirmed that EPO could stimulate bone marrow-derived Sca-1(+)CD44(+)CD11b(-)CD19(-) cells to secrete miR-144-containing EVs, which markedly suppressed tPA expression, as well as metalloproteinase 9 (MMP9) level and activity, in cultured renal fibroblasts. In conclusion, our study provides the first evidence that EPO protects mouse renal TBM through promoting bone marrow cells to generate and secrete miR-144, which, in turn, is efficiently delivered into the mouse kidney via EVs to inhibit the activation of the tPA/MMP9-mediated proteolytic network. This finding thus suggests that EPO, a hormone widely used to treat anemia in CKD, is a potential therapeutic strategy for renal fibrosis. PMID:26469975

  16. Tubular Coupling

    NASA Technical Reports Server (NTRS)

    Rosenbaum, Bernard J. (Inventor)

    2000-01-01

    A system for coupling a vascular overflow graft or cannula to a heart pump. A pump pipe outlet is provided with an external tapered surface which receives the end of a compressible connula. An annular compression ring with a tapered internal bore surface is arranged about the cannula with the tapered internal surface in a facing relationship to the external tapered surface. The angle of inclination of the tapered surfaces is converging such that the spacing between the tapered surfaces decreases from one end of the external tapered surface to the other end thereby providing a clamping action of the tapered surface on a cannula which increases as a function of the length of cannula segment between the tapered surfaces. The annular compression ring is disposed within a tubular locking nut which threadedly couples to the pump and provides a compression force for urging the annular ring onto the cannula between the tapered surfaces. The nut has a threaded connection to the pump body. The threaded coupling to the pump body provides a compression force for the annular ring. The annular ring has an annular enclosure space in which excess cannula material from the compression between the tapered surfaces to "bunch up" in the space and serve as an enlarged annular ring segment to assist holding the cannula in place. The clamped cannula provides a seamless joint connection to the pump pipe outlet where the clamping force is uniformly applied to the cannula because of self alignment of the tapered surfaces. The nut can be easily disconnected to replace the pump if necessary.

  17. Fast anodization fabrication of AAO and barrier perforation process on ITO glass

    NASA Astrophysics Data System (ADS)

    Liu, Sida; Xiong, Zuzhou; Zhu, Changqing; Li, Ma; Zheng, Maojun; Shen, Wenzhong

    2014-04-01

    Thin films of porous anodic aluminum oxide (AAO) on tin-doped indium oxide (ITO) substrates were fabricated through evaporation of a 1,000- to 2,000-nm-thick Al, followed by anodization with different durations, electrolytes, and pore widening. A faster method to obtain AAO on ITO substrates has been developed, which with 2.5 vol.% phosphoric acid at a voltage of 195 V at 269 K. It was found that the height of AAO films increased initially and then decreased with the increase of the anodizing time. Especially, the barrier layers can be removed by extending the anodizing duration, which is very useful for obtaining perforation AAO and will broaden the application of AAO on ITO substrates.

  18. Pulsed electrodeposition into AAO templates for CVD growth of carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Sklar, G. P.; Paramguru, K.; Misra, M.; La Combe, J. C.

    2005-08-01

    Anodic aluminium oxide (AAO) templates for multi-walled carbon nanotube (MWCNT) growth were produced by anodization of aluminium followed by pulse-reverse electrodeposition of cobalt inside the AAO pores. Cobalt functioned as the catalyst for H2/C2H2 chemical vapour deposition (CVD) growth of fairly well graphitized MWCNTs initiating inside the majority of the AAO pores and quickly growing beyond the pore confines. A technique is introduced for the production of AAO templates that fill evenly during pulsed electrodeposition. The electrodeposition produced an active metallic catalyst in the pore bottoms, with minimal over-filling. This process also eliminates the reduction step necessary when alternating current (AC) electrodeposition is used for filling AAO pores.

  19. Fast anodization fabrication of AAO and barrier perforation process on ITO glass

    PubMed Central

    2014-01-01

    Thin films of porous anodic aluminum oxide (AAO) on tin-doped indium oxide (ITO) substrates were fabricated through evaporation of a 1,000- to 2,000-nm-thick Al, followed by anodization with different durations, electrolytes, and pore widening. A faster method to obtain AAO on ITO substrates has been developed, which with 2.5 vol.% phosphoric acid at a voltage of 195 V at 269 K. It was found that the height of AAO films increased initially and then decreased with the increase of the anodizing time. Especially, the barrier layers can be removed by extending the anodizing duration, which is very useful for obtaining perforation AAO and will broaden the application of AAO on ITO substrates. PMID:24708829

  20. Fast anodization fabrication of AAO and barrier perforation process on ITO glass.

    PubMed

    Liu, Sida; Xiong, Zuzhou; Zhu, Changqing; Li, Ma; Zheng, Maojun; Shen, Wenzhong

    2014-01-01

    Thin films of porous anodic aluminum oxide (AAO) on tin-doped indium oxide (ITO) substrates were fabricated through evaporation of a 1,000- to 2,000-nm-thick Al, followed by anodization with different durations, electrolytes, and pore widening. A faster method to obtain AAO on ITO substrates has been developed, which with 2.5 vol.% phosphoric acid at a voltage of 195 V at 269 K. It was found that the height of AAO films increased initially and then decreased with the increase of the anodizing time. Especially, the barrier layers can be removed by extending the anodizing duration, which is very useful for obtaining perforation AAO and will broaden the application of AAO on ITO substrates. PMID:24708829

  1. Micro-Tubular Fuel Cells

    NASA Technical Reports Server (NTRS)

    Kimble, Michael C.; Anderson, Everett B.; Jayne, Karen D.; Woodman, Alan S.

    2004-01-01

    Micro-tubular fuel cells that would operate at power levels on the order of hundreds of watts or less are under development as alternatives to batteries in numerous products - portable power tools, cellular telephones, laptop computers, portable television receivers, and small robotic vehicles, to name a few examples. Micro-tubular fuel cells exploit advances in the art of proton-exchange-membrane fuel cells. The main advantage of the micro-tubular fuel cells over the plate-and-frame fuel cells would be higher power densities: Whereas the mass and volume power densities of low-pressure hydrogen-and-oxygen-fuel plate-and-frame fuel cells designed to operate in the targeted power range are typically less than 0.1 W/g and 0.1 kW/L, micro-tubular fuel cells are expected to reach power densities much greater than 1 W/g and 1 kW/L. Because of their higher power densities, micro-tubular fuel cells would be better for powering portable equipment, and would be better suited to applications in which there are requirements for modularity to simplify maintenance or to facilitate scaling to higher power levels. The development of PEMFCs has conventionally focused on producing large stacks of cells that operate at typical power levels >5 kW. The usual approach taken to developing lower-power PEMFCs for applications like those listed above has been to simply shrink the basic plate-and-frame configuration to smaller dimensions. A conventional plate-and-frame fuel cell contains a membrane/electrode assembly in the form of a flat membrane with electrodes of the same active area bonded to both faces. In order to provide reactants to both electrodes, bipolar plates that contain flow passages are placed on both electrodes. The mass and volume overhead of the bipolar plates amounts to about 75 percent of the total mass and volume of a fuel-cell stack. Removing these bipolar plates in the micro-tubular fuel cell significantly increases the power density.

  2. Surface and interface analysis of poly-hydroxyethylmethacrylate-coated anodic aluminium oxide membranes

    NASA Astrophysics Data System (ADS)

    Ali, Nurshahidah; Duan, Xiaofei; Jiang, Zhong-Tao; Goh, Bee Min; Lamb, Robert; Tadich, Anton; Poinern, Gérrard Eddy Jai; Fawcett, Derek; Chapman, Peter; Singh, Pritam

    2014-01-01

    The surface and interface of poly (2-hydroxyethylmethacrylate) (PHEMA) and anodic aluminium oxide (AAO) membranes were comprehensively investigated using Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. It was found that 1s→π* (Cdbnd O) and 1s→σ* (Csbnd O) transitions were dominant on the surface of both bulk PHEMA polymer and PHEMA-surface coated AAO (AAO-PHEMA) composite. Findings from NEXAFS, Fourier-Transform Infrared (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analyses suggest the possibility of chemical interaction between carbon from the ester group of polymer and AAO membrane.

  3. Nanoporous Aluminum Oxide Membranes Coated with Atomic Layer Deposition-Grown Titanium Dioxide for Biomedical Applications: An In Vitro Evaluation.

    PubMed

    Petrochenko, Peter E; Kumar, Girish; Fu, Wujun; Zhang, Qin; Zheng, Jiwen; Liang, Chengdu; Goering, Peter L; Narayan, Roger J

    2015-12-01

    The surface topographies of nanoporous anodic aluminum oxide (AAO) and titanium dioxide (TiO2) membranes have been shown to modulate cell response in orthopedic and skin wound repair applications. In this study, we: (1) demonstrate an improved atomic layer deposition (ALD) method for coating the porous structures of 20, 100, and 200 nm pore diameter AAO with nanometer-thick layers of TiO2 and (2) evaluate the effects of uncoated AAO and TiO2-coated AAO on cellular responses. The TiO2 coatings were deposited on the AAO membranes without compromising the openings of the nanoscale pores. The 20 nm TiO2-coated membranes showed the highest amount of initial protein adsorption via the micro bicinchoninic acid (micro-BCA) assay; all of the TiO2-coated membranes showed slightly higher protein adsorption than the uncoated control materials. Cell viability, proliferation, and inflammatory responses on the TiO2-coated AAO membranes showed no adverse outcomes. For all of the tested surfaces, normal increases in proliferation (DNA content) of L929 fibroblasts were observed over from 4 hours to 72 hours. No increases in TNF-alpha production were seen in RAW 264.7 macrophages grown on TiO2-coated AAO membranes compared to uncoated AAO membranes and tissue culture polystyrene (TCPS) surfaces. Both uncoated AAO membranes and TiO2-coated AAO membranes showed no significant effects on cell growth and inflammatory responses. The results suggest that TiO2-coated AAO may serve as a reasonable prototype material for the development of nanostructured wound repair devices and orthopedic implants. PMID:26510320

  4. Nanoporous aluminum oxide membranes coated with atomic layer deposition-grown titanium dioxide for biomedical applications: An in vitro evaluation

    DOE PAGESBeta

    Kumar, Girish; Fu, Wujun; Zhang, Qin Fen; Zheng, Jiwen; Liang, Chengdu; Goering, Peter L.; Narayan, Roger J.; Petrochenko, Peter E.

    2015-12-01

    The surface topographies of nanoporous anodic aluminum oxide (AAO) and titanium dioxide (TiO2) membranes have been shown to modulate cell response in orthopedic and skin wound repair applications. In this study, we: (1) demonstrate an improved atomic layer deposition (ALD) method for coating the porous structures of 20, 100, and 200 nm pore diameter AAO with nanometer-thick layers of TiO2 and (2) evaluate the effects of uncoated AAO and TiO2-coated AAO on cellular responses. The TiO2 coatings were deposited on the AAO membranes without compromising the openings of the nanoscale pores. The 20 nm TiO2-coated membranes showed the highest amountmore » of initial protein adsorption via the micro bicinchoninic acid (micro-BOA) assay; all of the TiO2-coated membranes showed slightly higher protein adsorption than the uncoated control materials. Cell viability, proliferation, and inflammatory responses on the TiO2-coated AAO membranes showed no adverse outcomes. For all of the tested surfaces, normal increases in proliferation (DNA content) of L929 fibroblasts were observed over from 4 hours to 72 hours. No increases in TNF-alpha production were seen in RAW 264.7 macrophages grown on TiO2-coated AAO membranes compared to uncoated AAO membranes and tissue culture polystyrene (TOPS) surfaces. Both uncoated AAO membranes and TiO2-coated AAO membranes showed no significant effects on cell growth and inflammatory responses. In conclusion, the results suggest that TiO2-coated AAO may serve as a reasonable prototype material for the development of nanostructured wound repair devices and orthopedic implants.« less

  5. Surface-modified anodic aluminum oxide membrane with hydroxyethyl celluloses as a matrix for bilirubin removal.

    PubMed

    Xue, Maoqiang; Ling, Yisheng; Wu, Guisen; Liu, Xin; Ge, Dongtao; Shi, Wei

    2013-01-01

    Microporous anodic aluminum oxide (AAO) membranes were modified by 3-glycidoxypropyltrimethoxysilane to produce terminal epoxy groups. These were used to covalently link hydroxyethyl celluloses (HEC) to amplify reactive groups of AAO membrane. The hydroxyl groups of HEC-AAO composite membrane were further modified with 1,4-butanediol diglycidyl ether to link arginine as an affinity ligand. The contents of HEC and arginine of arginine-immobilized HEC-AAO membrane were 52.1 and 19.7mg/g membrane, respectively. As biomedical adsorbents, the arginine-immobilized HEC-AAO membranes were tested for bilirubin removal. The non-specific bilirubin adsorption on the unmodified HEC-AAO composite membranes was 0.8mg/g membrane. Higher bilirubin adsorption values, up to 52.6mg/g membrane, were obtained with the arginine-immobilized HEC-AAO membranes. Elution of bilirubin showed desorption ratio was up to 85% using 0.3M NaSCN solution as the desorption agent. Comparisons equilibrium and dynamic capacities showed that dynamic capacities were lower than the equilibrium capacities. In addition, the adsorption mechanism of bilirubin and the effects of temperature, initial concentration of bilirubin, albumin concentration and ionic strength on adsorption were also investigated. PMID:23290920

  6. Humic acid removal and easy-cleanability using temperature-responsive ZrO2 tubular membranes grafted with poly(N-isopropylacrylamide) brush chains.

    PubMed

    Zhao, Yijiang; Zhou, Shouyong; Li, Meisheng; Xue, Ailian; Zhang, Yan; Wang, Jingang; Xing, Weihong

    2013-05-01

    New poly(N-isopropylacrylamide) brushes grafted with ZrO2 (PNIPAAm-g-ZrO2) composite membranes, which had been prepared in our laboratory, were used for humic acid (HA) removal. We found that the fluxes associated with such membranes, when compared to those obtained from unmodified ZrO2 membranes, declined slightly at both 25 °C and 35 °C. The PNIPAAm-g-ZrO2 membrane achieved a high rejection, of 98.0%, at a suitable steady flux of 111.9 L m(-2) h(-1) at 25 °C. This membrane exhibited good anti-fouling properties as well as improved membrane performance during filtration of HA. The important role of pH and Ca(2+) concentration in HA removal was also investigated. Lower adsorption fouling and a higher rejection were obtained at higher pH levels. The Ca(2+) ions reduced the electrostatic exclusion and played a cross-linking role between HA and the PNIPAAm-g-ZrO2 membrane surface. Fouling was severe in the presence of Ca(2+). These tests led to the development of an environment-friendly membrane cleaning method, by means of temperature-change water elution around LCST of PNIPAAm-brushes. After the alternate temperature-change (25 °C/35 °C) cleaning, a flux recovery of 98.2% was obtained for the PNIPAAm-g-ZrO2 membrane. Moreover, after four repeated experiments, the anti-fouling and easy-cleaning properties were still maintained. It is implied that PNIPAAm-brushes were firmly "stuck" to the membrane surface, and could not easily be removed by water cleaning or HA filtration. The PNIPAAm-g-ZrO2 membranes exhibited good stability and great potential for HA removal. PMID:23466218

  7. Nanoporous aluminum oxide membranes coated with atomic layer deposition-grown titanium dioxide for biomedical applications: An in vitro evaluation

    SciTech Connect

    Kumar, Girish; Fu, Wujun; Zhang, Qin Fen; Zheng, Jiwen; Liang, Chengdu; Goering, Peter L.; Narayan, Roger J.

    2015-12-01

    The surface topographies of nanoporous anodic aluminum oxide (AAO) and titanium dioxide (TiO2) membranes have been shown to modulate cell response in orthopedic and skin wound repair applications. In this study, we: (1) demonstrate an improved atomic layer deposition (ALD) method for coating the porous structures of 20, 100, and 200 nm pore diameter AAO with nanometer-thick layers of TiO2 and (2) evaluate the effects of uncoated AAO and TiO2-coated AAO on cellular responses. The TiO2 coatings were deposited on the AAO membranes without compromising the openings of the nanoscale pores. The 20 nm TiO2-coated membranes showed the highest amount of initial protein adsorption via the micro bicinchoninic acid (micro-BOA) assay; all of the TiO2-coated membranes showed slightly higher protein adsorption than the uncoated control materials. Cell viability, proliferation, and inflammatory responses on the TiO2-coated AAO membranes showed no adverse outcomes. For all of the tested surfaces, normal increases in proliferation (DNA content) of L929 fibroblasts were observed over from 4 hours to 72 hours. No increases in TNF-alpha production were seen in RAW 264.7 macrophages grown on TiO2-coated AAO membranes compared to uncoated AAO membranes and tissue culture polystyrene (TOPS) surfaces. Both uncoated AAO membranes and TiO2-coated AAO membranes showed no significant effects on cell growth and inflammatory responses. In conclusion, the results suggest that TiO2-coated AAO may serve as a reasonable prototype material for the development of nanostructured wound repair devices and orthopedic implants.

  8. A supramolecular tubular nanoreactor.

    PubMed

    Li, Zhi-Qiang; Zhang, Ying-Ming; Chen, Yong; Liu, Yu

    2014-07-01

    The extremely strong noncovalent complexation between the rigid host of phthalocyanine-bridged β-cyclodextrins and the amphiphilic guest carboxylated porphyrin is employed to construct a hollow tubular structure as a supramolecular nanoreactor. A representative coupling reaction occurs in the hydrophobic interlayers of the tubular walls in pure water at room temperature, leading to an enhancement of ten times higher reaction rate without any adverse effect on catalytic activity and conversion. PMID:24890802

  9. H2 production from simulated coal syngas containing H2S in multi-tubular Pd and 80 wt% Pd-20 wt% Cu membrane reactors

    SciTech Connect

    Iyoha, O.; Enick, R.M.; Killmeyer, R.P.; Howard, B.H.; Ciocco, M.V.; Morreale, B.

    2007-12-01

    99.7% conversion of CO in a simulated syngas feed containing 53% CO, 35% H2 and 12% CO2 was achieved via the water–gas shift (WGS) reaction in a counter-current Pd multi-tube membrane reactor (MR) at 1173 K and 2 s residence time. This conversion is significantly greater than the 32% equilibrium conversion associated with a conventional (non-membrane) reactor primarily due to the high rate of H2 extraction from the reaction zone through the Pd membranes at elevated temperatures. Furthermore, nearly complete H2 recovery was attained in the permeate, resulting in the simultaneous production of a high-pressure CO2 (>99%) retentate stream after condensation of the steam. When Pd80 wt%Cu tubes were used in the reactor, a significantly lower CO conversion of 68% was attained at comparable residence times, probably due to the lower H2 permeance of the alloy. When H2S was added to the syngas feed and the H2S-to-H2 ratio was maintained below the threshold required for thermodynamically stable sulfides to form, the Pd and Pd80 wt%Cu MRs retained their mechanical integrity and H2 selectivity, but a precipitous drop in CO conversion was observed due to deactivation of the catalytic surface. The Pd and Pd80 wt%Cu MRs were observed to fail within minutes after increasing the H2S-to-H2 ratio to levels above that expected for thermodynamically stable sulfides to form, as evidenced by rupturing of the membrane tubes. SEM–EDS analyses of the membranes suggested that at high H2S-to-H2 ratios, the H2S compromised the mechanical integrity of the MRs by preferentially attacking the grain boundary region.

  10. Influence of wet etching time cycles on morphology features of thin porous Anodic Aluminum oxide (AAO) template for nanostructure's synthesis

    NASA Astrophysics Data System (ADS)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Al-Diabat, Ahmad M.; Bououdina, M.

    2015-12-01

    This study examines the influence of chemical wet etching time cycles on the morphological features of thin porous AAO template. Pore widening via wet-etching treatment at room temperature was found to modify the pore quality of AAO template and reduces the barrier layer on the bottom of AAO pore array in order to facilitate uniform electrodeposition of nanostructures onto AAO template. High quality AAO pore arrays with different mean pore diameters (64, 70, and 87 nm) were prepared under controllable pore-widening time cycles of 10, 30 and 45 min at room temperature, respectively. The AAO templates and the produced Cu nanorods were characterized using FESEM, EDX, XRD and AFM. The results indicate that the morphology of the aligned arrays of Cu nanorods is strongly affected by the duration of etching and the removal of AAO template. This study showed that the optimum etching duration required to maintain the aligned nanorods without any fracture is approximately 5 min. In addition, the regular hemispherical concave Al surface ensuring the self-ordering of AAO pore can be established when striping is employed for 45 min. Thus, it can be inferred that the duration of wet etching treatment (striping) of Al oxide film performed after the first-step anodization plays a vital role in the final arrangement of nanopores.

  11. Supertubes and Superconducting Membranes

    SciTech Connect

    Cordero, Ruben; Miguel-Pilar, Zelin

    2007-02-09

    We show the equivalence between configurations that arise from string theory of type IIA, called supertubes, and superconducting membranes at the bosonic level. We find equilibrium and oscillating configurations for a tubular membrane carrying a current along its axis.

  12. The thermomechanical stability of micro-solid oxide fuel cells fabricated on anodized aluminum oxide membranes

    NASA Astrophysics Data System (ADS)

    Kwon, Chang-Woo; Lee, Jae-Il; Kim, Ki-Bum; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2012-07-01

    The thermomechanical stability of micro-solid oxide fuel cells (micro-SOFCs) fabricated on an anodized aluminum oxide (AAO) membrane template is investigated. The full structure consists of the following layers: AAO membrane (600 nm)/Pt anode/YSZ electrolyte (900 nm)/porous Pt cathode. The utilization of a 600-nm-thick AAO membrane significantly improves the thermomechanical stability due to its well-known honeycomb-shaped nanopore structure. Moreover, the Pt anode layer deposited in between the AAO membrane and the YSZ electrolyte preserves its integrity in terms of maintaining the triple-phase boundary (TPB) and electrical conductivity during high-temperature operation. Both of these results guarantee thermomechanical stability of the micro-SOFC and extend the cell lifetime, which is one of the most critical issues in the fabrication of freestanding membrane-type micro-SOFCs.

  13. Westinghouse tubular SOFC technology

    SciTech Connect

    Ray, E.R.

    1992-12-01

    A summary of significant developments and accomplishments which have recently occurred throughout the tubular Solidi Oxide Fuel Cell (SOFC) program include: Demonstration that thousands of tubular solid oxide fuel cells can be fabricated with consistent and reproducible performance. Continuous operation of a 3 kWe tubular SOFC system for over six months at a customer`s test site. Demonstration of stable performance and lifetime in excess of 5,300 hours for a 3 kWe generator module, operating on desulfurized natural gas without external humidification. Demonstration of stable performance and life times in excess of 30,000 hours in multiple single cell tests. Design, construction and operation of a dedicated cell, module and generator Pre-Pilot Manufacturing Facility (PPMF). Successful 6,840 hour bundle tests of 50 cm. cells produced at the PPMF. Significant improvements in cell performance and life and marked reduction in cell degradation. Design, construction and successful operation of a 20 kWe tubular solid oxide fuel cell generator module. Design, construction, shipment and installation of 25 kWe (40 kWe peak power) field units.

  14. Westinghouse tubular SOFC technology

    SciTech Connect

    Ray, E.R.

    1992-01-01

    A summary of significant developments and accomplishments which have recently occurred throughout the tubular Solidi Oxide Fuel Cell (SOFC) program include: Demonstration that thousands of tubular solid oxide fuel cells can be fabricated with consistent and reproducible performance. Continuous operation of a 3 kWe tubular SOFC system for over six months at a customer's test site. Demonstration of stable performance and lifetime in excess of 5,300 hours for a 3 kWe generator module, operating on desulfurized natural gas without external humidification. Demonstration of stable performance and life times in excess of 30,000 hours in multiple single cell tests. Design, construction and operation of a dedicated cell, module and generator Pre-Pilot Manufacturing Facility (PPMF). Successful 6,840 hour bundle tests of 50 cm. cells produced at the PPMF. Significant improvements in cell performance and life and marked reduction in cell degradation. Design, construction and successful operation of a 20 kWe tubular solid oxide fuel cell generator module. Design, construction, shipment and installation of 25 kWe (40 kWe peak power) field units.

  15. Effects of the voltage and time of anodization on modulation of the pore dimensions of AAO films for nanomaterials synthesis

    NASA Astrophysics Data System (ADS)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Maryam, W.; Ahmad, M. A.; Bououdina, M.

    2015-12-01

    Highly-ordered and hexagonal-shaped nanoporous anodic aluminum oxide (AAO) of 1 μm thickness of Al pre-deposited onto Si substrate using two-step anodization was successfully fabricated. The growth mechanism of the porous AAO film was investigated by anodization current-time behavior for different anodizing voltages and by visualizing the microstructural procedure of the fabrication of AAO film by two-step anodization using cross-sectional and top view of FESEM imaging. Optimum conditions of the process variables such as annealing time of the as-deposited Al thin film and pore widening time of porous AAO film were experimentally determined to obtain AAO films with uniformly distributed and vertically aligned porous microstructure. Pores with diameter ranging from 50 nm to 110 nm and thicknesses between 250 nm and 1400 nm, were obtained by controlling two main influential anodization parameters: the anodizing voltage and time of the second-step anodization. X-ray diffraction analysis reveals amorphous-to-crystalline phase transformation after annealing at temperatures above 800 °C. AFM images show optimum ordering of the porous AAO film anodized under low voltage condition. AAO films may be exploited as templates with desired size distribution for the fabrication of CuO nanorod arrays. Such nanostructured materials exhibit unique properties and hold high potential for nanotechnology devices.

  16. Tubular Secretion in CKD.

    PubMed

    Suchy-Dicey, Astrid M; Laha, Thomas; Hoofnagle, Andrew; Newitt, Rick; Sirich, Tammy L; Meyer, Timothy W; Thummel, Ken E; Yanez, N David; Himmelfarb, Jonathan; Weiss, Noel S; Kestenbaum, Bryan R

    2016-07-01

    Renal function generally is assessed by measurement of GFR and urinary albumin excretion. Other intrinsic kidney functions, such as proximal tubular secretion, typically are not quantified. Tubular secretion of solutes is more efficient than glomerular filtration and a major mechanism for renal drug elimination, suggesting important clinical consequences of secretion dysfunction. Measuring tubular secretion as an independent marker of kidney function may provide insight into kidney disease etiology and improve prediction of adverse outcomes. We estimated secretion function by measuring secreted solute (hippurate, cinnamoylglycine, p-cresol sulfate, and indoxyl sulfate) clearance using liquid chromatography-tandem mass spectrometric assays of serum and timed urine samples in a prospective cohort study of 298 patients with kidney disease. We estimated GFR by mean clearance of creatinine and urea from the same samples and evaluated associations of renal secretion with participant characteristics, mortality, and CKD progression to dialysis. Tubular secretion rate modestly correlated with eGFR and associated with some participant characteristics, notably fractional excretion of electrolytes. Low clearance of hippurate or p-cresol sulfate associated with greater risk of death independent of eGFR (hazard ratio, 2.3; 95% confidence interval, 1.1 to 4.7; hazard ratio, 2.5; 95% confidence interval, 1.0 to 6.1, respectively). Hazards models also suggested an association between low cinnamoylglycine clearance and risk of dialysis, but statistical analyses did not exclude the null hypothesis. Therefore, estimates of proximal tubular secretion function correlate with glomerular filtration, but substantial variability in net secretion remains. The observed associations of net secretion with mortality and progression of CKD require confirmation. PMID:26614381

  17. Proximal tubular NHEs: sodium, protons and calcium?

    PubMed Central

    Alexander, R. Todd; Dimke, Henrik; Cordat, Emmanuelle

    2016-01-01

    Na+/H+ exchange activity in the apical membrane of the proximal tubule is fundamental to the reabsorption of Na+ and water from the filtrate. The role of this exchange process in bicarbonate reclamation and, consequently, the maintenance of acid-base homeostasis has been appreciated for at least half a century and remains a pillar of renal tubular physiology. More recently, apical Na+/H+ exchange, mediated by Na+/H+ exchanger isoform 3 (NHE3), has been implicated in proximal tubular reabsorption of Ca2+ and Ca2+ homeostasis in general. Overexpression of NHE3 increased paracellular Ca2+ flux in a proximal tubular cell model. Consistent with this observation, mice with genetic deletion of Nhe3 have a noticable renal Ca2+ leak. These mice also display decreased intestinal Ca2+ uptake and osteopenia. This review highlights the traditional roles of proximal tubular Na+/H+ exchange and summarizes recent novel findings implicating the predominant isoform, NHE3, in Ca2+ homeostasis. PMID:23761670

  18. The biocompatibility and anti-biofouling properties of magnetic core-multishell Fe@C NWs-AAO nanocomposites.

    PubMed

    Lindo, André M; Pellicer, Eva; Zeeshan, Muhammad A; Grisch, Roman; Qiu, Famin; Sort, Jordi; Sakar, Mahmut S; Nelson, Bradley J; Pané, Salvador

    2015-05-28

    Soft-magnetic core-multishell Fe@C NWs-AAO nanocomposites were synthesized using anodization, electrodeposition and low-pressure chemical vapour deposition (CVD) at 900 °C. High chemical and mechanical stability is achieved by the conversion from amorphous to θ- and δ-Al2O3 phases above 600 °C. Moreover, the surface properties of the material evolve from bioactive, for porous AAO, to bioinert, for Fe@C NW filled AAO nanocomposite. Although the latter is not cytotoxic, cells do not adhere onto the surface of the magnetic nanocomposite, thus proving its anti-biofouling character. PMID:25920767

  19. Wnt5a Deficiency Leads to Anomalies in Ureteric Tree Development, Tubular Epithelial Cell Organization and Basement Membrane Integrity Pointing to a Role in Kidney Collecting Duct Patterning

    PubMed Central

    Pietilä, Ilkka; Prunskaite-Hyyryläinen, Renata; Kaisto, Susanna; Tika, Elisavet; van Eerde, Albertien M.; Salo, Antti M.; Garma, Leonardo; Miinalainen, Ilkka; Feitz, Wout F.; Bongers, Ernie M. H. F.; Juffer, André; Knoers, Nine V. A. M.; Renkema, Kirsten Y.; Myllyharju, Johanna; Vainio, Seppo J.

    2016-01-01

    The Wnts can be considered as candidates for the Congenital Anomaly of Kidney and Urinary Tract, CAKUT diseases since they take part in the control of kidney organogenesis. Of them Wnt5a is expressed in ureteric bud (UB) and its deficiency leads to duplex collecting system (13/90) uni- or bilateral kidney agenesis (10/90), hypoplasia with altered pattern of ureteric tree organization (42/90) and lobularization defects with partly fused ureter trunks (25/90) unlike in controls. The UB had also notably less tips due to Wnt5a deficiency being at E15.5 306 and at E16.5 765 corresponding to 428 and 1022 in control (p<0.02; p<0.03) respectively. These changes due to Wnt5a knock out associated with anomalies in the ultrastructure of the UB daughter epithelial cells. The basement membrane (BM) was malformed so that the BM thickness increased from 46.3 nm to 71.2 nm (p<0.01) at E16.5 in the Wnt5a knock out when compared to control. Expression of a panel of BM components such as laminin and of type IV collagen was also reduced due to the Wnt5a knock out. The P4ha1 gene that encodes a catalytic subunit of collagen prolyl 4-hydroxylase I (C-P4H-I) in collagen synthesis expression and the overall C-P4H enzyme activity were elevated by around 26% due to impairment in Wnt5a function from control. The compound Wnt5a+/-;P4ha1+/- embryos demonstrated Wnt5a-/- related defects, for example local hyperplasia in the UB tree. A R260H WNT5A variant was identified from renal human disease cohort. Functional studies of the consequence of the corresponding mouse variant in comparison to normal ligand reduced Wnt5a-signalling in vitro. Together Wnt5a has a novel function in kidney organogenesis by contributing to patterning of UB derived collecting duct development contributing putatively to congenital disease. PMID:26794322

  20. Wnt5a Deficiency Leads to Anomalies in Ureteric Tree Development, Tubular Epithelial Cell Organization and Basement Membrane Integrity Pointing to a Role in Kidney Collecting Duct Patterning.

    PubMed

    Pietilä, Ilkka; Prunskaite-Hyyryläinen, Renata; Kaisto, Susanna; Tika, Elisavet; van Eerde, Albertien M; Salo, Antti M; Garma, Leonardo; Miinalainen, Ilkka; Feitz, Wout F; Bongers, Ernie M H F; Juffer, André; Knoers, Nine V A M; Renkema, Kirsten Y; Myllyharju, Johanna; Vainio, Seppo J

    2016-01-01

    The Wnts can be considered as candidates for the Congenital Anomaly of Kidney and Urinary Tract, CAKUT diseases since they take part in the control of kidney organogenesis. Of them Wnt5a is expressed in ureteric bud (UB) and its deficiency leads to duplex collecting system (13/90) uni- or bilateral kidney agenesis (10/90), hypoplasia with altered pattern of ureteric tree organization (42/90) and lobularization defects with partly fused ureter trunks (25/90) unlike in controls. The UB had also notably less tips due to Wnt5a deficiency being at E15.5 306 and at E16.5 765 corresponding to 428 and 1022 in control (p<0.02; p<0.03) respectively. These changes due to Wnt5a knock out associated with anomalies in the ultrastructure of the UB daughter epithelial cells. The basement membrane (BM) was malformed so that the BM thickness increased from 46.3 nm to 71.2 nm (p<0.01) at E16.5 in the Wnt5a knock out when compared to control. Expression of a panel of BM components such as laminin and of type IV collagen was also reduced due to the Wnt5a knock out. The P4ha1 gene that encodes a catalytic subunit of collagen prolyl 4-hydroxylase I (C-P4H-I) in collagen synthesis expression and the overall C-P4H enzyme activity were elevated by around 26% due to impairment in Wnt5a function from control. The compound Wnt5a+/-;P4ha1+/- embryos demonstrated Wnt5a-/- related defects, for example local hyperplasia in the UB tree. A R260H WNT5A variant was identified from renal human disease cohort. Functional studies of the consequence of the corresponding mouse variant in comparison to normal ligand reduced Wnt5a-signalling in vitro. Together Wnt5a has a novel function in kidney organogenesis by contributing to patterning of UB derived collecting duct development contributing putatively to congenital disease. PMID:26794322

  1. Tubular toxicity of proteinuria.

    PubMed

    Baines, Richard J; Brunskill, Nigel J

    2011-03-01

    Proteinuria is a prognostic indicator of progressive kidney disease and poor cardiovascular outcomes. Abnormally filtered bioactive macromolecules interact with proximal tubular epithelial cells (PTECs), which results in the development of proteinuric nephropathy. This condition is characterized by alterations in PTEC growth, apoptosis, gene transcription and inflammatory cytokine production as a consequence of dysregulated signaling pathways that are stimulated by proteinuric tubular fluid. The megalin-cubilin complex mediates the uptake of several proteins, including albumin, into PTECs. Megalin might also possess intrinsic signaling properties and the ability to regulate cell signaling pathways and gene transcription after processing regulated intramembrane proteolysis. Megalin could, therefore, link abnormal PTEC albumin exposure with altered growth factor receptor activation, proinflammatory and profibrotic signaling, and gene transcription. Evidence now suggests that other PTEC pathways for protein reabsorption of (patho)physiological importance might be mediated by the neonatal Fc receptor and CD36. PMID:21151210

  2. Origin of the bottlenecks in preparing anodized aluminum oxide (AAO) templates on ITO glass.

    PubMed

    Foong, Thelese R B; Sellinger, Alan; Hu, Xiao

    2008-11-25

    Nanoporous anodic alumina (AAO) templates are routinely created with ease on substrates, particularly Si wafers. However, the inability to stabilize Al anodization on indium tin oxide (ITO) glass is a key stumbling block that has prevented AAO-assisted deposition of nanomaterial arrays extending from ITO that are attractive for a range of opto-electronic applications (e.g., solar cells and photonic devices). We report on the processing of stable AAO templates directly on ITO substrates by utilizing an ultrathin (0.3 nm) adhesion/passivation layer of Ti between ITO and Al. Precise control of the Ti layer thickness to within the subnanometer (0.2-0.5 nm) range is essential for the anodization process for two factors: (1) to prevent the delamination of Al and destruction of ITO; and (2) to prevent the formation of thick barrier layers at the bottom of the pore channels, which prevent pore connectivity to the conductive ITO substrate. We explore the complex correlation between the electrical properties of substrates (and interlayers) and barrier layer formation and further highlight the criteria for successful barrier layer removal. PMID:19206390

  3. Enhancing the platinum atomic layer deposition infiltration depth inside anodic alumina nanoporous membrane

    SciTech Connect

    Vaish, Amit Krueger, Susan; Dimitriou, Michael; Majkrzak, Charles; Vanderah, David J.; Chen, Lei; Gawrisch, Klaus

    2015-01-15

    Nanoporous platinum membranes can be straightforwardly fabricated by forming a Pt coating inside the nanopores of anodic alumina membranes (AAO) using atomic layer deposition (ALD). However, the high-aspect-ratio of AAO makes Pt ALD very challenging. By tuning the process deposition temperature and precursor exposure time, enhanced infiltration depth along with conformal coating was achieved for Pt ALD inside the AAO templates. Cross-sectional scanning electron microscopy/energy dispersive x-ray spectroscopy and small angle neutron scattering were employed to analyze the Pt coverage and thickness inside the AAO nanopores. Additionally, one application of platinum-coated membrane was demonstrated by creating a high-density protein-functionalized interface.

  4. Expandable tubulars for use in geologic structures

    DOEpatents

    Spray, Jeffery A.; Svedeman, Steven; Walter, David; Mckeighan, Peter; Siebanaler, Shane; Dewhurst, Peter; Hobson, Steven; Foss, Doug; Wirz, Holger; Sharpe, Aaron; Apostal, Michael

    2014-08-12

    An expandable tubular includes a plurality of leaves formed from sheet material that have curved surfaces. The leaves extend around a portion or fully around the diameter of the tubular structure. Some of the adjacent leaves of the tubular are coupled together. The tubular is compressed to a smaller diameter so that it can be inserted through previously deployed tubular assemblies. Once the tubular is properly positioned, it is deployed and coupled or not coupled to a previously deployed tubular assembly. The tubular is useful for all types of wells and boreholes.

  5. Impedance spectroscopy of highly ordered nano-porous electrodes based on Au-AAO (anodic aluminum oxide) structure.

    PubMed

    Ahn, Jaehwan; Cho, Sungbo; Min, Junhong

    2013-11-01

    Electrochemical measurements using the microelectrodes are increasingly utilized for the label-free detection of the small amount of biological materials such as DNA, protein, and cells. However, the interfacial electrode impedance increases and may hinder the detection of weak signals as the size of electrode decreases. To enhance the measurement sensitivity while reducing the electrode size, in this study, microelectrodes employing a nanoporous structure were fabricated and characterized by using electrical impedance spectroscopy. We made the highly ordered honeycomb nanoporous structure of Anodic Aluminum Oxide (AAO) by electrochemical anodizing and formed Au layer on the surface of AAO (Au/AAO) by electroless Au plating method. The electrical characteristics of the fabricated Au/AAO electrodes were evaluated by using de Levie's model derived for the pore electrodes. As a result, the interfacial electrode impedance of the fabricated Au/AAO electrodes was 2-3 order lower than the value of the planar electrodes at frequencies below 1 kHz. It implies this nanoporous electrode could be directly applied to label free detection of biomaterials. PMID:24245278

  6. Immobilized tubular fermentor

    SciTech Connect

    Gencer, M.A.; Mutharasan, R.

    1983-09-01

    In this article, a mathematical model describing the kinetics of ethanol fermentation in a whole cell immobilized tubular fermentor is proposed. Experimental results show reasonable agreement with the proposed model. A procedure for treating the fermentation data for determining the ethanol inhibition constants k1 and k2 is described. The ethanol productivity of the immobilized cell fermentor is compared with those of traditional fermentors. Experimental studies indicate that with Saccharomyces cerevisiae (NRRL Y132) culture, ethanol productivity in the range 21.2-83.7 g ethanol/L/h at ethanol concentration of 76-60 g/L can be achieved. This is comparable to or higher than those reported in the literature for yeast. The product yield factor of 0.5 g ethanol/g glucose was obtained. The immobilized cell fermentor does not show washout at dilution rates of 7/h and shows good stability over a 650-h operating period.

  7. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    Lapointe, Donat J. E. (Inventor); Wright, Lawrence T. (Inventor); Vincent, Laurence J. (Inventor)

    1987-01-01

    A tapered tubular polyester sleeve is described to serve as the flexible foundation for a spacesuit limb covering. The tube has a large end and a small end with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end. A requisite number of warp yarns extend the full length of the sleeve. Other warp yarns extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel, heated in an oven, and then attached to the arm or other limb of the spacesuit.

  8. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    LaPointe, Donat J. E. (Inventor); Vincent, Laurence J. (Inventor); Wright, Lawrence T. (Inventor)

    1988-01-01

    A tapered tubular polyester sleeve as set forth. It has a large end 12 and a small end 14 with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end 12. A requisite number of warp yarns 16 extend the full length of the sleeve. Other warp yarns exemplified at 18, 22, 26, 28, 30 and 32 extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn 40 which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel 42, heated in an oven 44 and is thereafter placed on the arm or other limb of a space suit exemplified at 50.

  9. [The SERS Detection of Sudan I by Using AAO as Template to Prepare the Substrate].

    PubMed

    Pan, Xiao-hui; Zhang, Qin; Guo, Wei; Chen, Fa-he

    2015-06-01

    The large-scale controllable, ordered two-dimensional arrays of gold nanostructure with hot-spot were prepared together with chemical molecules were modified on the surface to concentrate Sudan I within the zone of the SERS effect, which lead to analytical detection of Sudan I in high resolution. The vapor of gold was deposed on anodic aluminum oxide(AAO) template by -200 nm thickness to replicate its nanochannels, and the negative structure i. e. large-scale ordered gold nano-hemisphere array, was obtained after the removal of the template of AAO by NaOH solution. Au nano-hemisphere array was modified by 1-Dodecanethiol which can be self-assembled monolayer on the surface and concentrate Sudan I within the zone of the SERS detection, which can facilitate the measurement of Sudan I. Due to the order and regularity of Au nano-hemisphere array, the signal of Sudan I in the range of laser illumination is stable and uniform, and the quantitative analysis of Sudan I was realized. The SERS intensity of Sudan I is logistic proportional to the concentration in the range of 10(-7) to 5 x 10(-4) mol x L(-1). The corresponding correlation coefficient of the liner equation is 0.99, the recoveries of Sudan I are between 77% - 117%. The limit of detection for Sudan I is 4 x 10(-1) mol x L(-1), comparable to that of HPLC of Chinese national standard method. PMID:26601366

  10. Steam reforming of methanol over copper loaded anodized aluminum oxide (AAO) prepared through electrodeposition

    NASA Astrophysics Data System (ADS)

    Linga Reddy, E.; Karuppiah, J.; Lee, Hyun Chan; Kim, Dong Hyun

    2014-12-01

    In order to study the steam reforming of methanol (SRM) to produce hydrogen for fuel cells, porous γ-alumina support is developed on Al substrate using anodic oxidation process and copper catalyst particles are deposited homogeneously over anodic aluminum oxide (AAO) surface by electrodeposition method. We investigated the effect of electrodeposition time and hot water treatment (HWT) on the activity of catalysts for SRM reaction in the temperature range between 160 and 360 °C. The experimental results indicate that the SRM activity, CO2 and dimethyl ether (DME) selectivity's over Cu catalysts increased as the electrodeposition time increased from 30 to 120 s, further increment in deposition time of Cu have no significant effect on it. The rates of SRM conversion are found to be higher for the catalysts made from the supports obtained after HWT, which may be due to the enhancement in the surface area of AAO support. It is found that the SRM activity and CO2 selectivity strongly depended upon the free exposed copper sites available for methanol adsorption and reaction, and DME in products is mainly observed in the reaction temperature range between 300 and 350 °C and it is higher for the catalysts with low Cu content.

  11. Mechanisms of albumin uptake by proximal tubular cells.

    PubMed

    Brunskill, N

    2001-01-01

    The likely role of albumin in the induction tubulo-interstitial injury in proteinuria has stimulated considerable interest in the entry of albumin into the proximal tubule and its subsequent uptake by proximal tubular cells. Currently, there is considerable controversy over the degree of glomerular permeability to albumin. After filtration, however, albumin binds to megalin and cubulin, two giant receptors in the apical membrane of proximal tubular cells. Albumin is subsequently re-absorbed by proximal tubular cells by receptor-mediated endocytosis, a process subject to complex regulation. The interaction of albumin with proximal tubule cells also leads to the generation of intracellular signals. The understanding of these pathways may provide important insights into the pathogenesis of renal scarring in proteinuria. PMID:11158855

  12. Stacked pulse-electroplated CoNiMnP-AAO nanocomposite permanent magnets for MEMS

    NASA Astrophysics Data System (ADS)

    Wu, P. R.; Chao, T. Y.; Cheng, Y. T.

    2015-12-01

    The paper presents a CMOS compatible pulse-electroplating technique combined with a low temperature bonding process for the synthesis of CoNiMnP-AAO (anodic alumina oxide) nanocomposite films and the fabrication of stacked composite permanent magnets (PMs). The magnetic nanocomposite film exhibits the best characteristics of the coercivity of 2472 Oe, remanence of 4000 G, and {{≤ft(\\text{BH}\\right)}\\max} of 16.13 kJ m-3, in the existing CoNiMnP systems. Meanwhile, a surface magnetic flux density of 9.2 mT generated by a 15-layer-stacked composite PM with a volume of 9 mm3 has shown the potential for various magnetic microelectromechanical systems (MEMS) fabrication using the nanocomposite material.

  13. Flux calibration of the AAO/UKST SuperCOSMOS Hα Survey

    NASA Astrophysics Data System (ADS)

    Frew, David J.; Bojičić, Ivan S.; Parker, Quentin A.; Pierce, Mark J.; Gunawardhana, M. L. P.; Reid, W. A.

    2014-05-01

    The AAO/UKST SuperCOSMOS Hα Survey (SHS) was, when completed in 2003, a powerful addition to extant wide-field surveys. The combination of areal coverage, spatial resolution and sensitivity in a narrow imaging band, still marks it out today as an excellent resource for the astronomical community. The 233 separate fields are available online in digital form, with each field covering 25 deg2. The SHS has been the motivation for equivalent surveys in the north, and new digital Hα surveys now beginning in the south such as VPHAS+. It has been the foundation of many important discovery projects with the Macquarie/AAO/Strasbourg Hα planetary nebula project being a particularly successful example. However, the full potential of the SHS has been hampered by lack of a clear route to acceptable flux calibration from the base photographic data. We have determined the calibration factors for 170 individual SHS fields, and present a direct pathway to the measurement of integrated Hα fluxes and surface brightnesses for resolved nebulae detected in the SHS. We also include a catalogue of integrated Hα fluxes for >100 planetary and other nebulae measured from the SHS, and use these data to show that fluxes, accurate to ±0.10-0.14 dex (˜25-35 per cent), can be obtained from these fields. For the remaining 63 fields, a mean calibration factor of 12.0 counts pixel-1 R-1 can be used, allowing the determination of reasonable integrated fluxes accurate to better than ±0.2 dex (˜50 per cent). We outline the procedures involved and the caveats that need to be appreciated in achieving such flux measurements. This paper forms a handy reference source that will significantly increase the scientific utility of the SHS.

  14. Renal tubular vasopressin receptors downregulated by dehydration

    SciTech Connect

    Steiner, M.; Phillips, M.I. )

    1988-03-01

    Receptors for arginine vasopressin (AVP) were characterized in tubular epithelial basolateral membranes (BL membranes) prepared from the kidneys of male Spraque-Dawley rats. Association of ({sup 3}H)AVP was rapid, reversible, and specific. Saturation studies revealed a single class of saturable binding sites with a maximal binding (B{sub max}) of 184 {plus minus} 15 fmol/mg protein. The V{sub 2} receptor antagonist was more than 3,700 times as effective in displacing ({sup 3}H)AVP than was the V{sub 1} antagonist. To investigate the physiological regulation of vasopressin receptors, the effects of elevated levels of circulating AVP on receptor characteristics were studied. Seventy-two-hour water deprivation significantly elevated plasma osmolality and caused an 11.5-fold increase in plasma (AVP). Scatchard analysis revealed a 38% decreased in the number of AVP receptors on the BL membranes from dehydrated animals. The high-affinity binding sites on the BL membranes fit the pharmacological profile for adenylate cyclase-linked vasopressin receptors (V{sub 2}), which mediate the antidiuretic action of the hormone. The authors conclude that physiologically elevated levels of AVP can downregulate vasopressin receptors in the kidney.

  15. Device for inserting tubular members together

    SciTech Connect

    Milberger, L.J.

    1992-03-17

    This patent describes a well, a lower tubular member with a sealing surface located in the well, an upper tubular member which inserts into engagement with the lower tubular member during running in, the upper and lower tubular members being exposed to well fluid pressure, an improved means for sliding the upper tubular member into engagement with the lower tubular member. It comprises the upper tubular member having a first side and a second side, the second side having a sealing section which mates with the sealing surface of the lower tubular sidewall; axially spaced apart seal means located on the running tool sidewall for sealingly engaging the first side of the upper tubular member above and below the sealing section during running in, for defining a low pressure area between the running tool and the first side which is isolated from the well fluid pressure; the sealing section of the upper tubular member being exposed to well fluid pressure during running in, resulting in a pressure difference across the upper tubular member between the first side of the tubular member and the sealing section, means for eliminating the pressure difference across the upper tubular member between the first side and the sealing section after the upper tubular member has reached its engaged position with the lower tubular member, allowing the sealing section to move radially into engagement with the sealing surface. This patent also describes a method for sliding an upper tubular member into engagement with a sealing surface of a lower tubular member in a well having well fluid pressure, comprising in combination: providing the upper tubular member with a first side and a second side and providing the second side with a sealing section for mating with the sealing surface of the lower tubular member.

  16. A strategy for depositing different types of cells in three dimensions to mimic tubular structures in tissues.

    PubMed

    Yuan, Bo; Jin, Yu; Sun, Yi; Wang, Dong; Sun, Jiashu; Wang, Zhuo; Zhang, Wei; Jiang, Xingyu

    2012-02-14

    The fabrication of tubular structures, with multiple cell types forming different layers of the tube walls, is described using a stress-induced rolling membrane (SIRM). Cell orientation inside the tubes can also be controlled by topographical contact guidance. These layered tubes precisely mimic blood vessels and many other tubular structures, suggesting that they may be of great use in tissue engineering. PMID:22403828

  17. A NAP-AAO3 Regulatory Module Promotes Chlorophyll Degradation via ABA Biosynthesis in Arabidopsis Leaves[W][OPEN

    PubMed Central

    Yang, Jiading; Worley, Eric

    2014-01-01

    Chlorophyll degradation is an important part of leaf senescence, but the underlying regulatory mechanisms are largely unknown. Excised leaves of an Arabidopsis thaliana NAC-LIKE, ACTIVATED BY AP3/PI (NAP) transcription factor mutant (nap) exhibited lower transcript levels of known chlorophyll degradation genes, STAY-GREEN1 (SGR1), NON-YELLOW COLORING1 (NYC1), PHEOPHYTINASE (PPH), and PHEIDE a OXYGENASE (PaO), and higher chlorophyll retention than the wild type during dark-induced senescence. Transcriptome coexpression analysis revealed that abscisic acid (ABA) metabolism/signaling genes were disproportionately represented among those positively correlated with NAP expression. ABA levels were abnormally low in nap leaves during extended darkness. The ABA biosynthetic genes 9-CIS-EPOXYCAROTENOID DIOXYGENASE2, ABA DEFICIENT3, and ABSCISIC ALDEHYDE OXIDASE3 (AAO3) exhibited abnormally low transcript levels in dark-treated nap leaves. NAP transactivated the promoter of AAO3 in mesophyll cell protoplasts, and electrophoretic mobility shift assays showed that NAP can bind directly to a segment (−196 to −162 relative to the ATG start codon) of the AAO3 promoter. Exogenous application of ABA increased the transcript levels of SGR1, NYC1, PPH, and PaO and suppressed the stay-green phenotype of nap leaves during extended darkness. Overexpression of AAO3 in nap leaves also suppressed the stay-green phenotype under extended darkness. Collectively, the results show that NAP promotes chlorophyll degradation by enhancing transcription of AAO3, which leads to increased levels of the senescence-inducing hormone ABA. PMID:25516602

  18. Chemical synthesis, characterisation, and biocompatibility of nanometre scale porous anodic aluminium oxide membranes for use as a cell culture substrate for the vero cell line: a preliminary study.

    PubMed

    Poinern, Gérrard Eddy Jai; Le, Xuan Thi; O'Dea, Mark; Becker, Thomas; Fawcett, Derek

    2014-01-01

    In this preliminary study we investigate for the first time the biomedical potential of using porous anodic aluminium oxide (AAO) membranes as a cell substrate for culturing the Cercopithecus aethiops (African green monkey) Kidney (Vero) epithelial cell line. One advantage of using the inorganic AAO membrane is the presence of nanometre scale pore channels that allow the exchange of molecules and nutrients across the membrane. The size of the pore channels can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The cellular interaction and response of the Vero cell line with an in-house synthesised AAO membrane, a commercially available membrane, and a glass control were assessed by investigating cell adhesion, morphology, and proliferation over a 72 h period. The number of viable cells proliferating over the respective membrane surfaces revealed that the locally produced in-house AAO membrane had cells numbers similar to the glass control. The study revealed evidence of focal adhesion sites over the surface of the nanoporous membranes and the penetration of cellular extensions into the pore structure as well. The outcome of the study has revealed that nanometre scale porous AAO membranes have the potential to become practical cell culture scaffold substrates with the capability to enhance adhesion and proliferation of Vero cells. PMID:24579077

  19. Chemical Synthesis, Characterisation, and Biocompatibility of Nanometre Scale Porous Anodic Aluminium Oxide Membranes for Use as a Cell Culture Substrate for the Vero Cell Line: A Preliminary Study

    PubMed Central

    Poinern, Gérrard Eddy Jai; Le, Xuan Thi; Becker, Thomas; Fawcett, Derek

    2014-01-01

    In this preliminary study we investigate for the first time the biomedical potential of using porous anodic aluminium oxide (AAO) membranes as a cell substrate for culturing the Cercopithecus aethiops (African green monkey) Kidney (Vero) epithelial cell line. One advantage of using the inorganic AAO membrane is the presence of nanometre scale pore channels that allow the exchange of molecules and nutrients across the membrane. The size of the pore channels can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The cellular interaction and response of the Vero cell line with an in-house synthesised AAO membrane, a commercially available membrane, and a glass control were assessed by investigating cell adhesion, morphology, and proliferation over a 72 h period. The number of viable cells proliferating over the respective membrane surfaces revealed that the locally produced in-house AAO membrane had cells numbers similar to the glass control. The study revealed evidence of focal adhesion sites over the surface of the nanoporous membranes and the penetration of cellular extensions into the pore structure as well. The outcome of the study has revealed that nanometre scale porous AAO membranes have the potential to become practical cell culture scaffold substrates with the capability to enhance adhesion and proliferation of Vero cells. PMID:24579077

  20. Tubular lysosome morphology and distribution within macrophages depend on the integrity of cytoplasmic microtubules

    SciTech Connect

    Swanson, J.; Bushnell, A.; Silverstein, S.C.

    1987-04-01

    Pinocytosis of the fluorescent dye lucifer yellow labels elongated, membrane-bound tubular organelles in several cell types, including cultured human monocytes, thioglycolate-elicited mouse peritoneal macrophages, and the macrophage-like cell line J774.2. These tubular structures can be identified as lysosomes by acid phosphatase histochemistry and immunofluorescence localization of cathepsin L. The abundance of tubular lysosomes is markedly increased by treatment with phorbol 12-myristate 13-acetate. When labeled by pinocytosis of microperoxidase and examined by electron microscopic histochemistry, the tubular lysosomes have an outside diameter of approx. = 75 nm and a length of several micrometers; they radiate from the cell's centrosphere in alignment with cytoplasmic microtubules and intermediate filaments. Incubation of phorbol myristate acetate-treated macrophages at 4/sup 0/C or in medium containing 5 ..mu..M colchicine or nocodazole at 37/sup 0/C leads to disassembly of microtubules and fragmentation of the tubular lysosomes. Return of the cultures to 37/sup 0/C or removal of nocodazole from the medium leads to reassembly of microtubules and the reappearance of tubular lysosomes within 10-20 min. The authors conclude that microtubules are essential for the maintenance of tubular lysosome morphology and that, in macrophages, a significant proportion of the lysosomal compartment is contained within these tubular structures.

  1. Responses of Proximal Tubular Cells to Injury in Congenital Renal Disease: Fight or Flight

    PubMed Central

    Chevalier, Robert L.; Forbes, Michael S.; Galarreta, Carolina I.; Thornhill, Barbara A.

    2013-01-01

    Most chronic kidney disease in children results from congenital or inherited disorders, which can be studied in mouse models. Following 2 weeks of unilateral ureteral obstruction (UUO) in the adult mouse, nephron loss is due to proximal tubular mitochondrial injury and cell death. In neonatal mice, proximal tubular cell death is delayed beyond 2 weeks of complete UUO, and release of partial UUO allows remodeling of remaining nephrons. Progressive cyst expansion develops in polycystic kidney disease (PKD), a common inherited renal disorder. The PCY mutant mouse (which develops late-onset PKD) develops thinning of the glomerulotubular junction in parallel with growth of cysts in adulthood. Renal insufficiency in nephropathic cystinosis, a rare inherited renal disorder, results from progressive tubular cystine accumulation. In the Ctns knock out mouse (a model of cystinosis), proximal tubular cells become flattened, with loss of mitochondria and thickening of tubular basement membrane. In each model, persistent obstructive or metabolic stress leads ultimately to the formation of atubular glomeruli. The initial “fight” response (proximal tubular survival) switches to a “flight” response (proximal tubular cell death) with ongoing oxidative injury and mitochondrial damage. Therapies should be directed at reducing proximal tubular mitochondrial oxidative injury to enhance repair and regeneration. PMID:23949631

  2. Preparation of thin hexagonal highly-ordered anodic aluminum oxide (AAO) template onto silicon substrate and growth ZnO nanorod arrays by electrodeposition

    NASA Astrophysics Data System (ADS)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Qaeed, M. A.; Bououdina, M.

    2014-12-01

    In this study, anodic aluminum oxide (AAO) templates of Aluminum thin films onto Ti-coated silicon substrates were prepared for growth of nanostructure materials. Hexagonally highly ordered thin AAO templates were fabricated under controllable conditions by using a two-step anodization. The obtained thin AAO templates were approximately 70 nm in pore diameter and 250 nm in length with 110 nm interpore distances within an area of 3 cm2. The difference between first and second anodization was investigated in details by in situ monitoring of current-time curve. A bottom barrier layer of the AAO templates was removed during dropping the voltage in the last period of the anodization process followed by a wet etching using phosphoric acid (5 wt%) for several minutes at ambient temperature. As an application, Zn nanorod arrays embedded in anodic alumina (AAO) template were fabricated by electrodeposition. Oxygen was used to oxidize the electrodeposited Zn nanorods in the AAO template at 700 °C. The morphology, structure and photoluminescence properties of ZnO/AAO assembly were analyzed using Field-emission scanning electron microscope (FESEM), Energy dispersive X-ray spectroscopy (EDX), Atomic force microscope (AFM), X-ray diffraction (XRD) and photoluminescence (PL).

  3. SERS activity with tenfold detection limit optimization on a type of nanoporous AAO-based complex multilayer substrate

    NASA Astrophysics Data System (ADS)

    Sui, Chaofan; Wang, Kaige; Wang, Shuang; Ren, Junying; Bai, Xiaohong; Bai, Jintao

    2016-03-01

    Most of SERS applications are constricted by heterogeneous hotspots and aggregates of nanostructure, which result in low sensitivity and poor reproducibility of characteristic signals. This work intends to introduce SERS properties of a type of SERS-active substrate, Au-CuCl2-AAO, which is innovatively developed on a porous anodic alumina oxide (AAO) template. Spectral measuring results of Rhodamine 6G (R6G) on this substrate optimized by controlling morphology and gold thickness showed that enhancement factor (2.30 × 107) and detection limit (10-10 M) were both improved and represented better performance than its template AAO. Homogenous hot spots across the region of interest were achieved by scanning SERS intensity distribution for the band at 1505 cm-1 in 5 × 5 μm2 area. Furthermore, the promising SERS activity of the flower-patterned substrate was theoretically explained through simulation of the electromagnetic field distribution. In addition, this SERS substrate is proposed for applications within the field of chemical and biochemical analyses.Most of SERS applications are constricted by heterogeneous hotspots and aggregates of nanostructure, which result in low sensitivity and poor reproducibility of characteristic signals. This work intends to introduce SERS properties of a type of SERS-active substrate, Au-CuCl2-AAO, which is innovatively developed on a porous anodic alumina oxide (AAO) template. Spectral measuring results of Rhodamine 6G (R6G) on this substrate optimized by controlling morphology and gold thickness showed that enhancement factor (2.30 × 107) and detection limit (10-10 M) were both improved and represented better performance than its template AAO. Homogenous hot spots across the region of interest were achieved by scanning SERS intensity distribution for the band at 1505 cm-1 in 5 × 5 μm2 area. Furthermore, the promising SERS activity of the flower-patterned substrate was theoretically explained through simulation of the

  4. Effects of anodic aluminum oxide membrane on performance of nanostructured solar cells

    NASA Astrophysics Data System (ADS)

    Dang, Hongmei; Singh, Vijay

    2015-05-01

    Three nanowire solar cell device configurations have been fabricated to demonstrate the effects of the host anodized aluminum oxide (AAO) membrane on device performance. The three configurations show similar transmittance spectra, indicating that AAO membrane has negligible optical absorption. Power conversion efficiency (PCE) of the device is studied as a function of the carrier transport and collection in cell structures with and without AAO membrane. Free standing nanowire solar cells exhibit PCE of 9.9%. Through inclusion of AAO in solar cell structure, interface defects and traps caused by humidity and oxygen are reduced, and direct contact of CdTe tentacles with SnO2 and formation of micro shunt shorts are prevented; hence PCE is improved to 11.1%-11.3%. Partially embedded nanowire solar cells further reduce influence of non-ideal and non-uniform nanowire growth and generate a large amount of carriers in axial direction and also a small quantity of carriers in lateral direction, thus becoming a promising solar cell structure. Thus, including AAO membrane in solar cell structure provides favorable electro-optical properties as well as mechanical advantages.

  5. A Simple Tubular Reactor Experiment.

    ERIC Educational Resources Information Center

    Hudgins, Robert R.; Cayrol, Bertrand

    1981-01-01

    Using the hydrolysis of crystal violet dye by sodium hydroxide as an example, the theory, apparatus, and procedure for a laboratory demonstration of tubular reactor behavior are described. The reaction presented can occur at room temperature and features a color change to reinforce measured results. (WB)

  6. Research Perspectives: The 2013 AAOS/ORS Research Symposium on Bone Quality and Fracture Prevention

    PubMed Central

    Donnelly, Eve; Lane, Joseph M.; Boskey, Adele L.

    2016-01-01

    Bone fracture resistance is determined by the amount of bone present (“bone quantity”) and by a number of other geometric and material factors grouped under the term “bone quality.” In May 2013, a workshop was convened among a group of clinicians and basic science investigators to review the current state of the art in Bone Quality and Fracture Prevention and to make recommendations for future directions for research. The AAOS/ORS/OREF workshop was attended by 64 participants, including two representatives of the National Institutes of Arthritis and Musculoskeletal and Skin Diseases and 13 new investigators whose posters stimulated additional interest. A key outcome of the workshop was a set of recommendations regarding clinically relevant aspects of both bone quality and quantity that clinicians can use to inform decisions about patient care and management. The common theme of these recommendations was the need for more education of clinicians in areas of bone quality and for basic science studies to address specific topics of pathophysiology, diagnosis, prevention, and treatment of altered bone quality. In this report, the organizers with the assistance of the speakers and other attendees highlight the major findings of the meeting that justify the recommendations and needs for this field. PMID:24700449

  7. DC electrodeposition of NiGa alloy nanowires in AAO template

    NASA Astrophysics Data System (ADS)

    Maleki, K.; Sanjabi, S.; Alemipour, Z.

    2015-12-01

    NiGa alloy nanowires were electrodeposited from an acidic sulfate bath into nanoporous anodized alumina oxide (AAO). This template was fabricated by two-step anodizing. The effects of bath composition and current density were explored on the Ga content of electrodeposited nanowires. The Ga content in the deposits was increased by increasing both Ga in the bath composition and electrodepositing current density. The NiGa alloy nanowires were synthesized for Ga content up to 2-4% without significant improving the magnetic properties. Above this threshold Ga clusters were formed and decreased the magnetic properties of the nanowires. For Ga content of the alloy above 30%, the wires were too short and incomplete. X-ray diffraction patterns reveal that the significant increase of Ga content in the nanowires, changes the FCC crystal structure of Ni to an amorphous phase. It also causes a sizeable increase in the Ga cluster size; these both lead to a significant reduction in the coercivity and the magnetization respectively.

  8. Methane emissions from a full-scale A/A/O wastewater treatment plant.

    PubMed

    Wang, Jinhe; Zhang, Jian; Xie, Huijun; Qi, Pengyu; Ren, Yangang; Hu, Zhen

    2011-05-01

    Methane (CH(4)) emissions from a full-scale anaerobic/anoxic/oxic (A/A/O) wastewater treatment plant (WWTP) (Jinan, China) were investigated during spring and summer of 2010. Results showed that the major emission sources of CH(4) performed the following descending order: anaerobic tanks, oxic tanks, aerated grit chambers and sludge concentration tanks. The total annual fluxes of CH(4) emissions from the Jinan WWTP were 1.69 × 10(4)kg yr(-1), with the emission factors of per capita emissions of 11.3g CH(4) person(-1)yr(-1) and flow-based emissions of 1.55 × 10(-4)g CH(4) (L of wastewater)(-1). The estimated source strength of methane for all WWTPs in China was 6.2 Gg yr(-1) (1 Gg=10(9)g). The most significant factors influencing methane emissions were dissolved oxygen concentration in aerated grit chamber and oxic tank and water temperature in high density settler tanks. PMID:21084185

  9. Laser-MBE of nickel nanowires using AAO template: a new active substrate of surface enhanced Raman scattering.

    PubMed

    Zhang, Lisheng; Fang, Yan; Zhang, Pengxiang

    2008-01-01

    The highly ordered anodic aluminum oxide (AAO) template was fabricated using aluminum anodizing in electrolytes with two-step method, which apertures were about 50-80nm. The nickel nanowires with about 40-70nm in diameter was prepared on the AAO template by laser-MBE (molecular beam epitaxy). And high quality Raman spectra of SudanII were obtained on the glass covered with the nickel nanowires. On the nickel nanowires there are both surface enhanced Raman scattering (SERS) and tip enhanced Raman scattering (TERS). The new observations not only enlarge the range of SERS applications, but also imply a possible new enhancement mechanism. Otherwise the Raman and SERS frequencies of SudanII molecule were calculated using, respectively, DFT and B3PW91. PMID:17627875

  10. Synthesis of Hollow Nanorods of SiO2 Anode Material by AAO Template Synthesis Method for Lithium Ion Battery.

    PubMed

    Yoo, Gi-Won; Kim, Cheong; Jang, Byeong-Chan; Yang, Su-Bin; Son, Jong-Tae

    2015-11-01

    Silicon oxide hollow nanorods (SiO2-HNs) were prepared via a two-step anodization of aluminum template. SiO2 was synthesized using tetraethyl orthosilicate (TEOS) as the Si source that has not been applied to the anodic aluminum oxide (AAO) template method. The SiO2-HNs obtained were characterized by X-ray diffraction, scanning electron microscopy and electrochemical test. The results show that SiO2 nanorods with hollow morphology were successfully formed by the AAO template. The SiO2-HNs were investigated as an anode material for lithium-ion batteries and delivered an initial reversible capacity of 1344.26 mA h g(-1) at a current density of 17 mAg(-1). To the best of our knowledge, this is the first report of the synthesis of SiO2-HN using TEOS as the Si source by a two-step anodization of AAO template. PMID:26726592

  11. SERS activity with tenfold detection limit optimization on a type of nanoporous AAO-based complex multilayer substrate.

    PubMed

    Sui, Chaofan; Wang, Kaige; Wang, Shuang; Ren, Junying; Bai, Xiaohong; Bai, Jintao

    2016-03-21

    Most of SERS applications are constricted by heterogeneous hotspots and aggregates of nanostructure, which result in low sensitivity and poor reproducibility of characteristic signals. This work intends to introduce SERS properties of a type of SERS-active substrate, Au-CuCl2-AAO, which is innovatively developed on a porous anodic alumina oxide (AAO) template. Spectral measuring results of Rhodamine 6G (R6G) on this substrate optimized by controlling morphology and gold thickness showed that enhancement factor (2.30 × 10(7)) and detection limit (10(-10) M) were both improved and represented better performance than its template AAO. Homogenous hot spots across the region of interest were achieved by scanning SERS intensity distribution for the band at 1505 cm(-1) in 5 × 5 μm(2) area. Furthermore, the promising SERS activity of the flower-patterned substrate was theoretically explained through simulation of the electromagnetic field distribution. In addition, this SERS substrate is proposed for applications within the field of chemical and biochemical analyses. PMID:26911325

  12. Ultrafast excited state deactivation of doped porous anodic alumina membranes

    NASA Astrophysics Data System (ADS)

    Makhal, Abhinandan; Sarkar, Soumik; Pal, Samir Kumar; Yan, Hongdan; Wulferding, Dirk; Cetin, Fatih; Lemmens, Peter

    2012-08-01

    Free-standing, bi-directionally permeable and ultra-thin anodic aluminum oxide (AAO) membranes establish attractive templates (host) for the synthesis of nano-dots and rods of various materials (guest). This is due to their chemical and structural integrity and high periodicity on length scales of 5-150 nm which are often used to host photoactive nano-materials for various device applications including dye-sensitized solar cells. In the present study, AAO membranes are synthesized by using electrochemical methods and a detailed structural characterization using FEG-SEM, XRD and TGA confirms the porosity and purity of the material. Defect-mediated photoluminescence quenching of the porous AAO membrane in the presence of an electron accepting guest organic molecule (benzoquinone) is studied by means of steady-state and picosecond/femtosecond-resolved luminescence measurements. Using time-resolved luminescence transients, we have also revealed light harvesting of complexes of porous alumina impregnated with inorganic quantum dots (Maple Red) or gold nanowires. Both the Förster resonance energy transfer and the nano-surface energy transfer techniques are employed to examine the observed quenching behavior as a function of the characteristic donor-acceptor distances. The experimental results will find their relevance in light harvesting devices based on AAOs combined with other materials involving a decisive energy/charge transfer dynamics.

  13. Tumor-promoting phorbol esters effect alkalinization of canine renal proximal tubular cells

    SciTech Connect

    Mellas, J.; Hammerman, M.R.

    1986-03-01

    We have demonstrated the presence of specific receptors for tumor-promoting phorbol esters in the plasma membrane of the canine renal proximal tubular cell. These compounds affect proximal tubular metabolism in vitro. For example, we have shown that they inhibit gluconeogenesis in canine renal proximal tubular segments. Tumor-promoting phorbol esters have been shown to effect alkalinization of non-renal cells, by enhancing Na/sup +/-H/sup +/ exchange across the plasma membrane. To determine whether the actions of tumor-promoting phorbol esters in proximal tubular segments might be mediated by a similar process, we incubated suspensions of segments from dog kidney with these compounds and measured changes in intracellular pH using (/sup 14/C)-5,5-dimethoxazoladine-2-4-dione (DMO) and flow dialysis. Incubation of segments with phorbol 12,13 dibutyrate, but not inactive phorbol ester, 4 ..gamma.. phorbol, effected alkalinization of cells within the segments in a concentration-dependent manner. Alkalinization was dependent upon the presence of extracellular (Na/sup +/) > intracellular (Na/sup +/), was prevented by amiloride and was demonstrable in the presence of SITS. Our findings suggest that tumor-promoting esters stimulate the Na/sup +/-H/sup +/ exchanger known to be present in the brush border membrane of the renal proximal tubular cell. It is possible that the stimulation reflects a mechanism by which phorbol esters affect metabolic processes in these cells.

  14. Three-dimensional nanotube electrode arrays for hierarchical tubular structured high-performance pseudocapacitors.

    PubMed

    Gao, Yuan; Lin, Yuanjing; Chen, Jiaqi; Lin, Qingfeng; Wu, Yue; Su, Wenjun; Wang, Wenli; Fan, Zhiyong

    2016-07-21

    Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with high uniformity. The large surface area of such a structure leads to remarkable surface area enhancement up to 51.8 times compared to a planar structure. Combining with electrochemically deposited manganese dioxide (MnO2) nanoflakes on the inner side wall of the FTO nanotubes, the unique hierarchical tubular structured pseudocapacitor electrode demonstrated the highest areal capacitance of 193.8 mF cm(-2) at the scan rate of 5 mV s(-1) and 184 mF cm(-2) at the discharge current density of 0.6 mA cm(-2), which is 18.5 times that of a planar electrode. And it also showed a volumetric capacitance of 112.6 F cm(-3) at the scan rate of 5 mV s(-1) and 108.8 F cm(-3) at the discharge current density of 0.6 mA cm(-2). In addition, the cyclic stability test also indicated that a nanostructured pseudocapacitive electrode has a much larger capacitance retention after 3000 cycles of the charge-discharge process compared with a planar electrode, primarily due to the mechanical stability of the nanostructure. Moreover, pseudocapacitor device fabrication based on such electrodes shows the volumetric capacitance of 17.5 F cm(-3), and the highest specific energy of 1.56 × 10(-3) Wh cm(-3). With the merit of facile fabrication procedures and largely enhanced electrochemical performance, such a 3-D structure has high potency for energy storage systems for a wide range of practical applications. PMID:27337295

  15. Renal tubular secretion of pramipexole.

    PubMed

    Knop, Jana; Hoier, Eva; Ebner, Thomas; Fromm, Martin F; Müller, Fabian

    2015-11-15

    The dopamine agonist pramipexole is cleared predominantly by the kidney with a major contribution of active renal secretion. Previously the organic cation transporter 2 (OCT2) was shown to be involved in the uptake of pramipexole by renal tubular cells, while the mechanism underlying efflux into tubular lumen remains unclear. Cimetidine, a potent inhibitor of multidrug and toxin extrusion proteins 1 (MATE1) and 2-K (MATE2-K), decreases renal pramipexole clearance in humans. We hypothesized that, in addition to OCT2, pramipexole may be a substrate of MATE-mediated transport. Pramipexole uptake was investigated using MDCK or HEK cells overexpressing OCT2, MATE1 or MATE2-K and the respective vector controls (Co). Transcellular pramipexole transport was investigated in MDCK cells single- or double-transfected with OCT2 and/or MATE1 and in Co cells, separating a basal from an apical compartment in a model for renal tubular secretion. Pramipexole uptake was 1.6-, 1.1-, or 1.6-folds in cells overexpressing OCT2, MATE1 or MATE2-K, respectively as compared to Co cells (p<0.05). In transcellular transport experiments, intracellular pramipexole accumulation was 1.7-folds in MDCK-OCT2 (p<0.001), and transcellular pramipexole transport was 2.2- and 4.0-folds in MDCK-MATE1 and MDCK-OCT2-MATE1 cells as compared to Co cells (p<0.001). Transcellular pramipexole transport was pH dependent and inhibited by cimetidine with IC50 values of 12μM and 5.5μM in MATE1 and OCT2-MATE1 cells, respectively. Taken together, coordinate activity of OCT2-mediated uptake and MATE-mediated efflux determines pramipexole renal secretion. Reduced OCT2 or MATE transport activity due to genetic variation or drug-drug interactions may affect pramipexole renal secretion. PMID:26360835

  16. AAO-assisted synthesis of highly ordered, large-scale TiO2 nanowire arrays via sputtering and atomic layer deposition.

    PubMed

    Yao, Zhao; Wang, Cong; Li, Yang; Kim, Nam-Young

    2015-01-01

    Highly ordered nanoporous anodic aluminum oxide (AAO) thin films were fabricated in oxalic acid under a constant voltage via a two-step anodization process. To investigate the high-aspect-ratio (7.5:1) filling process, both sputtering and atomic layer deposition (ALD) were used to form TiO2 nanowires. Field emission scanning electron microscopy and high-resolution transmission electron microscopy images indicated that mushroom-like TiO2 structures were sputtered onto the AAO template surface, and the ALD-coated TiO2 exhibited fine filling results and clear crystal grain boundaries. Large-scale and free-standing TiO2 nanowire arrays were liberated by selectively removing the aluminum substrate and AAO template via a wet etching process with no collapsing or agglomeration after the drying process. ALD-deposited TiO2 nanowire arrays that were 67 nm in diameter and 400 nm high were transferred from the AAO template. The ALD process enabled the rapid, simple synthesis of highly ordered TiO2 nanowire arrays with desired parameters such as diameter, density, and thickness determined using diverse AAO templates. PMID:25897309

  17. AAO-assisted synthesis of highly ordered, large-scale TiO2 nanowire arrays via sputtering and atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Yao, Zhao; Wang, Cong; Li, Yang; Kim, Nam-Young

    2015-04-01

    Highly ordered nanoporous anodic aluminum oxide (AAO) thin films were fabricated in oxalic acid under a constant voltage via a two-step anodization process. To investigate the high-aspect-ratio (7.5:1) filling process, both sputtering and atomic layer deposition (ALD) were used to form TiO2 nanowires. Field emission scanning electron microscopy and high-resolution transmission electron microscopy images indicated that mushroom-like TiO2 structures were sputtered onto the AAO template surface, and the ALD-coated TiO2 exhibited fine filling results and clear crystal grain boundaries. Large-scale and free-standing TiO2 nanowire arrays were liberated by selectively removing the aluminum substrate and AAO template via a wet etching process with no collapsing or agglomeration after the drying process. ALD-deposited TiO2 nanowire arrays that were 67 nm in diameter and 400 nm high were transferred from the AAO template. The ALD process enabled the rapid, simple synthesis of highly ordered TiO2 nanowire arrays with desired parameters such as diameter, density, and thickness determined using diverse AAO templates.

  18. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J; Hryn, John N; Elam, Jeffrey W

    2013-08-27

    A nanoporous catalytic membrane which displays several unique features Including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity. Also provided is a method for producing a catalytic membrane having flow-through pores and discreet catalytic clusters adhering to the inside surfaces of the pores.

  19. Tubular inverse opal scaffolds for biomimetic vessels

    NASA Astrophysics Data System (ADS)

    Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

    2016-07-01

    There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels.There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially

  20. Acquired distal renal tubular acidosis in man.

    PubMed

    Better, O S

    1982-10-01

    Distal renal tubular acidosis (dRTA) may complicate renal transplantation, liver cirrhosis, and obstructive uropathy. Indeed, its occurrence may be an early clue to an episode of rejection of the graft or to obstructive uropathy. The mechanism in most patients with dRTA is impaired distal secretion of protons. In some patients, however, back leak of protons from tubular lumen to blood may abolish distal tubular ability to maintain urine to blood proton gradients. In patients with obstructive uropathy the spectrum of tubular acidosis is widened by the occurrence of additional defects in tubular secretion of potassium and impairment of hydrogen ion secretion secondary to hypoaldosteronism. Hyperkalemia is also seen in "voltage dependent" states such as following the administration of lithium and amiloride. Hyperkalemia per se is conducive to acidosis by a combination of extrarenal and several intrarenal mechanisms. PMID:6755051

  1. Cooperation of MICAL-L1, syndapin2, and phosphatidic acid in tubular recycling endosome biogenesis

    PubMed Central

    Giridharan, Sai Srinivas Panapakkam; Cai, Bishuang; Vitale, Nicolas; Naslavsky, Naava; Caplan, Steve

    2013-01-01

    Endocytic transport necessitates the generation of membrane tubules and their subsequent fission to transport vesicles for sorting of cargo molecules. The endocytic recycling compartment, an array of tubular and vesicular membranes decorated by the Eps15 homology domain protein, EHD1, is responsible for receptor and lipid recycling to the plasma membrane. It has been proposed that EHD dimers bind and bend membranes, thus generating recycling endosome (RE) tubules. However, recent studies show that molecules interacting with CasL-Like1 (MICAL-L1), a second, recently identified RE tubule marker, recruits EHD1 to preexisting tubules. The mechanisms and events supporting the generation of tubular recycling endosomes were unclear. Here, we propose a mechanism for the biogenesis of RE tubules. We demonstrate that MICAL-L1 and the BAR-domain protein syndapin2 bind to phosphatidic acid, which we identify as a novel lipid component of RE. Our studies demonstrate that direct interactions between these two proteins stabilize their association with membranes, allowing for nucleation of tubules by syndapin2. Indeed, the presence of phosphatidic acid in liposomes enhances the ability of syndapin2 to tubulate membranes in vitro. Overall our results highlight a new role for phosphatidic acid in endocytic recycling and provide new insights into the mechanisms by which tubular REs are generated. PMID:23596323

  2. Mars Life? - Microscopic Tubular Structures

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This electron microscope image shows tubular structures of likely Martian origin. These structures are very similar in size and shape to extremely tiny microfossils found in some Earth rocks. This photograph is part of a report by a NASA research team published in the Aug. 16, 1996, issue of the journal Science. A two-year investigation by the team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller.

  3. Mars Life? - Microscopic Tubular Structures

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This electron microscope image shows extremely tiny tubular structures that are possible microscopic fossils of bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller. The fossil-like structures were found in carbonate minerals formed along pre-existing fractures in the meteorite in a fashion similar to the way fossils occur in limestone on Earth, although on a microscopic scale.

  4. Separation of methane-nitrogen mixtures using synthesis vertically aligned carbon nanotube membranes

    NASA Astrophysics Data System (ADS)

    Gilani, Neda; Daryan, Jafar Towfighi; Rashidi, Alimorad; Omidkhah, Mohammad Reza

    2012-03-01

    In this paper, capabilities of carbon nanotube (CNT) membranes fabricated in cylindrical pores of anodic aluminum oxide (AAO) substrate to separate the binary mixtures of CH4/N2 are studied experimentally. For this purpose, the permeability and selectivity of three CNT/AAO membranes with different growth time as 6 h, 12 h and 18 h are investigated. CNTs are grown vertically through holes of AAO with average pore diameter of 45 nm by chemical vapor deposition (CVD) of acetylene gas. CNT/AAO membranes with the same CNTs' outer diameters and different inner diameters are synthesized. The AAO are characterized by SEM analysis. In addition, SEM, TEM, BET N2 adsorption analysis and Raman spectroscopy are employed to characterize aligned CNTs. Study on permeability and selectivity of membranes for three binary mixtures of CH4/N2 showed that when the CNT inner diameters are 34 nm and 24 nm, viscous flow is the governing mechanism and insignificant selectivities of 1.2-1.24 are achieved. However, the membrane with CNT inner diameter and wall thickness of 8 nm and 16 nm respectively is considerably selective for CH4 over N2. It was also found that CH4 mole fraction in the feed and upstream feed pressure have major effect on permeability and selectivity. The membrane with 18 h synthesis time showed the selectivity is in the range of 1.8-3.85. The enhancement factor for N2 single gas diffusivity was also found to be about three times larger than that predicted by Knudsen diffusion model.

  5. Tubular Unimolecular Transmembrane Channels: Construction Strategy and Transport Activities.

    PubMed

    Si, Wen; Xin, Pengyang; Li, Zhan-Ting; Hou, Jun-Li

    2015-06-16

    Lipid bilayer membranes separate living cells from their environment. Membrane proteins are responsible for the processing of ion and molecular inputs and exports, sensing stimuli and signals across the bilayers, which may operate in a channel or carrier mechanism. Inspired by these wide-ranging functions of membrane proteins, chemists have made great efforts in constructing synthetic mimics in order to understand the transport mechanisms, create materials for separation, and develop therapeutic agents. Since the report of an alkylated cyclodextrin for transporting Cu(2+) and Co(2+) by Tabushi and co-workers in 1982, chemists have constructed a variety of artificial transmembrane channels by making use of either the multimolecular self-assembly or unimolecular strategy. In the context of the design of unimolecular channels, important advances have been made, including, among others, the tethering of natural gramicidin A or alamethicin and the modification of various macrocycles such as crown ethers, cyclodextrins, calixarenes, and cucurbiturils. Many of these unimolecular channels exhibit high transport ability for metal ions, particularly K(+) and Na(+). Concerning the development of artificial channels based on macrocyclic frameworks, one straightforward and efficient approach is to introduce discrete chains to reinforce their capability to insert into bilayers. Currently, this approach has found the widest applications in the systems of crown ethers and calixarenes. We envisioned that for macrocycle-based unimolecular channels, control of the arrangement of the appended chains in the upward and/or downward direction would favor the insertion of the molecular systems into bilayers, while the introduction of additional interactions among the chains would further stabilize a tubular conformation. Both factors should be helpful for the formation of new efficient channels. In this Account, we discuss our efforts in designing new unimolecular artificial channels from

  6. 2015 Equilibrium Committee Amendment to the 1995 AAO-HNS Guidelines for the Definition of Ménière's Disease.

    PubMed

    Goebel, Joel A

    2016-03-01

    Ménière's disease is a disorder of the inner ear that causes attacks of vertigo and hearing loss, tinnitus, aural fullness in the involved ear. Over the past 4 decades, the Equilibrium Committee of the AAO-HNS has issued guidelines for diagnostic criteria, with the latest version being published in 1995. These criteria were reviewed in 2015 by the Equilibrium Committee, and revisions were approved at the recent meeting of the committee at the 2015 AAO-HNSF Annual Meeting. The following commentary outlines the amended and approved criteria. PMID:26884364

  7. Catalytic nanoporous membranes

    DOEpatents

    Pellin, Michael J.; Hryn, John N.; Elam, Jeffrey W.

    2009-12-01

    A nanoporous catalytic membrane which displays several unique features including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity.

  8. A family of carbon-based nanocomposite tubular structures created by in situ electron beam irradiation.

    PubMed

    Liu, Jian-Wei; Xu, Jie; Ni, Yong; Fan, Feng-Jia; Zhang, Chuan-Ling; Yu, Shu-Hong

    2012-05-22

    We report a unique approach for the fabrication of a family of curling tubular nanostructures rapidly created by a rolling up of carbon membranes under in situ TEM electron beam irradiation. Multiwall tubes can also be created if irradiation by electron beam is performed long enough. This general approach can be extended to curve the conductive carbon film loaded with various functional nanomaterials, such as nanocrystals, nanorods, nanowires, and nanosheets, providing a unique strategy to make composite tubular structures and composite materials by a combination of desired optical, electronic, and magnetic properties, which could find potential applications, including fluid transportation, encapsulation, and capillarity on the nanometer scale. PMID:22530775

  9. Tubular inverse opal scaffolds for biomimetic vessels.

    PubMed

    Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

    2016-07-14

    There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels. PMID:27241065

  10. Characterization of Anodic Aluminum Oxide Membrane with Variation of Crystallizing Temperature for pH Sensor.

    PubMed

    Yeo, Jin-Ho; Lee, Sung-Gap; Jo, Ye-Won; Jung, Hye-Rin

    2015-11-01

    We fabricated electrolyte-dielectric-metal (EDM) device incorporating a high-k Al2O3 sensing membrane from a porous anodic aluminum oxide (AAO) using a two step anodizing process for pH sensors. In order to change the properties of the AAO template, the crystallizing temperature was varied from 400 degrees C to 700 degrees C over 2 hours. The structural properties were observed by field emission scanning electron microscopy (FE-SEM). The pH sensitivity increased with an increase in the crystallizing temperature from 400 degrees C to 600 degrees C. However at 700 degrees C, deformation occurred. The porous AAO sensor with a crystallizing temperature of 600 degrees C displayed the good sensitivity and long-term stability and the values were 55.7 mV/pH and 0.16 mV/h, respectively. PMID:26726567

  11. The Reticulon and Dp1/Yop1p Proteins Form Immobile Oligomers in the Tubular Endoplasmic Reticulum*S⃞

    PubMed Central

    Shibata, Yoko; Voss, Christiane; Rist, Julia M.; Hu, Junjie; Rapoport, Tom A.; Prinz, William A.; Voeltz, Gia K.

    2008-01-01

    We recently identified a class of membrane proteins, the reticulons and DP1/Yop1p, which shape the tubular endoplasmic reticulum (ER) in yeast and mammalian cells. These proteins are highly enriched in the tubular portions of the ER and virtually excluded from other regions. To understand how they promote tubule formation, we characterized their behavior in cellular membranes and addressed how their localization in the ER is determined. Using fluorescence recovery after photobleaching, we found that yeast Rtn1p and Yop1p are less mobile in the membrane than normal ER proteins. Sucrose gradient centrifugation and cross-linking analyses show that they form oligomers. Mutants of yeast Rtn1p, which no longer localize exclusively to the tubular ER or are even totally inactive in inducing ER tubules, are more mobile and oligomerize less extensively. The mammalian reticulons and DP1 are also relatively immobile and can form oligomers. The conserved reticulon homology domain that includes the two membrane-embedded segments is sufficient for the localization of the reticulons to the tubular ER, as well as for their diffusional immobility and oligomerization. Finally, ATP depletion in both yeast and mammalian cells further decreases the mobilities of the reticulons and DP1. We propose that oligomerization of the reticulons and DP1/Yop1p is important for both their localization to the tubular domains of the ER and for their ability to form tubules. PMID:18442980

  12. Ileal bladder substitute: antireflux nipple or afferent tubular segment?

    PubMed

    Studer, U E; Spiegel, T; Casanova, G A; Springer, J; Gerber, E; Ackermann, D K; Gurtner, F; Zingg, E J

    1991-01-01

    Spheroidal bladder substitutes made from double-folded ileal segments, similar to Goodwin's cup-patch technique, are devoid of major coordinated wall contractions. This, together with the reservoir's direct anastomosis to the membranous urethra, prevents major intraluminal pressure peaks and assures a residue-free voiding of sterile urine. In order to determine whether, under these conditions, an afferent tubular isoperistaltic ileal segment of 20-cm length protects the upper urinary tract as efficiently as an antireflux nipple, 60 male patients who were subjected to radical cystectomy were prospectively randomised to groups in which a bladder substitute was formed together with either of these 2 antireflux devices. An analysis of the results obtained in 20 patients from each group who could be followed for more than 1 year (median observation time 30 and 36 months) showed no differences between the groups in metabolic disturbances, kidney size, reservoir capacity, diurnal and nocturnal urinary continence, the incidence of urinary tract infection or episodes of acute pyelonephritis. Later than 1 year postoperatively, intravenous urograms of the renoureteral units of 25% of the patients with antireflux nipples showed persistent but generally slight dilatation of the upper urinary tracts. This observation was significantly more frequent than it was in patients with afferent tubular segments. Urodynamic and radiographic studies showed that the competence of the antireflux nipples was secured by the raised surrounding intravesical pressure. This, however, also resulted in a transient functional obstruction, and a gradual rise of the basal pressure in the upper urinary tracts was recorded. In patients with afferent ileal tubular segments, contrast medium could be forced upwards into the renal pelvis when the bladder substitutes were overfilled. However, despite raised intravesical pressures, peristalsis in the isoperistaltic afferent tubular segment gradually returned

  13. Tubular endocytosis drives remodelling of the apical surface during epithelial morphogenesis in Drosophila.

    PubMed

    Fabrowski, Piotr; Necakov, Aleksandar S; Mumbauer, Simone; Loeser, Eva; Reversi, Alessandra; Streichan, Sebastian; Briggs, John A G; De Renzis, Stefano

    2013-01-01

    During morphogenesis, remodelling of cell shape requires the expansion or contraction of plasma membrane domains. Here we identify a mechanism underlying the restructuring of the apical surface during epithelial morphogenesis in Drosophila. We show that the retraction of villous protrusions and subsequent apical plasma membrane flattening is an endocytosis-driven morphogenetic process. Quantitation of endogenously tagged GFP::Rab5 dynamics reveals a massive increase in apical endocytosis that correlates with changes in apical morphology. This increase is accompanied by the formation of tubular plasma membrane invaginations that serve as platforms for the de novo generation of Rab5-positive endosomes. We identify the Rab5-effector Rabankyrin-5 as a regulator of this pathway and demonstrate that blocking dynamin activity results in the complete inhibition of tubular endocytosis, in the disappearance of Rab5 endosomes, and in the inhibition of surface flattening. These data collectively demonstrate a requirement for endocytosis in morphogenetic remodelling during epithelial development. PMID:23921440

  14. Tubular Liposomes with Variable Permeability for Reconstitution of FtsZ Rings

    PubMed Central

    Osawa, Masaki; Erickson, Harold P.

    2012-01-01

    We have developed a system for producing tubular multilamellar liposomes that incorporate the protein FtsZ on the inside. We start with a mixture of spherical multilamellar liposomes with FtsZ initially on the outside. Shearing forces generated by applying a coverslip most likely distort some of the spherical liposomes into a tubular shape, and causes some to leak and incorporate FtsZ inside. We describe protocols for liposome preparation, and for preparing membrane-targeted FtsZ that can assemble contractile Z rings inside the tubular liposomes. We also describe the characterization of the multilamellar liposomes in terms of the permeability or leakiness for a small fluorescent dye and larger protein molecules. These liposomes may be useful for reconstitution of other biological systems. PMID:19903547

  15. VCP-dependent muscle degeneration is linked to defects in a dynamic tubular lysosomal network in vivo

    PubMed Central

    Johnson, Alyssa E; Shu, Huidy; Hauswirth, Anna G; Tong, Amy; Davis, Graeme W

    2015-01-01

    Lysosomes are classically viewed as vesicular structures to which cargos are delivered for degradation. Here, we identify a network of dynamic, tubular lysosomes that extends throughout Drosophila muscle, in vivo. Live imaging reveals that autophagosomes merge with tubular lysosomes and that lysosomal membranes undergo extension, retraction, fusion and fission. The dynamics and integrity of this tubular lysosomal network requires VCP, an AAA-ATPase that, when mutated, causes degenerative diseases of muscle, bone and neurons. We show that human VCP rescues the defects caused by loss of Drosophila VCP and overexpression of disease relevant VCP transgenes dismantles tubular lysosomes, linking tubular lysosome dysfunction to human VCP-related diseases. Finally, disruption of tubular lysosomes correlates with impaired autophagosome-lysosome fusion, increased cytoplasmic poly-ubiquitin aggregates, lipofuscin material, damaged mitochondria and impaired muscle function. We propose that VCP sustains sarcoplasmic proteostasis, in part, by controlling the integrity of a dynamic tubular lysosomal network. DOI: http://dx.doi.org/10.7554/eLife.07366.001 PMID:26167652

  16. Treatment of well tubulars with gelatin

    SciTech Connect

    Lowther, F.E.

    1992-08-04

    This patent describes a method for treating a tubular in a well. It comprises: passing a mass of gelatin downward through the tubular; and passing the mass of gelating, upward in the well tubular toward the surface. This patent also describes a method of treating tubulars in a cased well having at least one string of tubing therein. It comprises positioning a mass in the annulus formed between the casing and the at least one string of tubing; and passing the mass downward in the annulus and in contact with both the inner wall of the casing and the outer wall of the tubing to deposit a protective layer on each of the walls.

  17. METHOD AND APPARATUS FOR FABRICATING TUBULAR UNITS

    DOEpatents

    Haldeman, G.W.

    1959-02-24

    A method and apparatus are described for fabricating tubular assemblies such as clad fuel elements for nuclear reactors. According to this method, a plurality of relatively short cylindrical slug-shaped members are inserted in an outer protective tubular jacket, and the assembly is passed through a reducing die to draw the outer tubular member into tight contact with the slug members, the slugs being automatically spaced with respect to each other and helium being inserted during the drawing operation to fill the spaces. The apparatus includes a pusher rod which functions to space the slugelements equidistantly by pushing on them in the direction of drawing but traveling at a slower rate than that of the tubular member.

  18. The North Slope of Alaska and Adjacent Arctic Ocean (NSA/AAO) cart site begins operation: Collaboration with SHEBA and FIRE

    SciTech Connect

    Zak, D. B.; Church, H.; Ivey, M.; Yellowhorse, L.; Zirzow, J.; Widener, K. B.; Rhodes, P.; Turney, C.; Koontz, A.; Stamnes, K.; Storvold, R.; Eide, H. A.; Utley, P.; Eagan, R.; Cook, D.; Hart, D.; Wesely, M.

    2000-04-04

    Since the 1997 Atmospheric Radiation Measurement (ARM) Science Team Meeting, the North Slope of Alaska and Adjacent Arctic Ocean (NSA/AAO) Cloud and Radiation Testbed (CART) site has come into being. Much has happened even since the 1998 Science Team Meeting at which this paper was presented. To maximize its usefulness, this paper has been updated to include developments through July 1998.

  19. An open tubular ion chromatograph.

    PubMed

    Yang, Bingcheng; Zhang, Min; Kanyanee, Tinakorn; Stamos, Brian N; Dasgupta, Purnendu K

    2014-12-01

    We describe an open tubular ion chromatograph (OTIC) that uses anion exchange latex coated 5 μm radius silica and 9.8 μm radius poly(methyl methacrylate) tubes and automated time/pressure based hydrodynamic injection for pL-nL scale injections. It is routinely possible to generate 50,000 plates or more (up to 150,000 plates/m, columns between 0.3 and 0.8 m have been used), and as such, fast separations are possible, comparable to or in some cases better than the current practice of IC. With an optimized admittance detector, nonsuppressed detection permits LODs of submicromolar to double digit micromolar for a variety of analytes. However, large volume injections are possible and can significantly improve on this. A variety of eluents, the use of organic modifiers, and variations of eluent pH can be used to tailor a given separation. The approach is discussed in the context of extraterrestrial exploration, especially Mars, where the existence of large amounts of perchlorate in the soil needs to be confirmed. These columns can survive drying and freezing, and small footprint, low power consumption, and simplicity make OTIC a good candidate for such a mission. PMID:25394230

  20. Shear Stress-Induced Alteration of Epithelial Organization in Human Renal Tubular Cells

    PubMed Central

    Belloy, Marcy; Saulnier-Blache, Jean-Sébastien; Casemayou, Audrey; Ducasse, Laure; Grès, Sandra; Bellière, Julie; Caubet, Cécile; Bascands, Jean-Loup; Schanstra, Joost P.; Buffin-Meyer, Bénédicte

    2015-01-01

    Tubular epithelial cells in the kidney are continuously exposed to urinary fluid shear stress (FSS) generated by urine movement and recent in vitro studies suggest that changes of FSS could contribute to kidney injury. However it is unclear whether FSS alters the epithelial characteristics of the renal tubule. Here, we evaluated in vitro and in vivo the influence of FSS on epithelial characteristics of renal proximal tubular cells taking the organization of junctional complexes and the presence of the primary cilium as markers of epithelial phenotype. Human tubular cells (HK-2) were subjected to FSS (0.5 Pa) for 48h. Control cells were maintained under static conditions. Markers of tight junctions (Claudin-2, ZO-1), Par polarity complex (Pard6), adherens junctions (E-Cadherin, β-Catenin) and the primary cilium (α-acetylated Tubulin) were analysed by quantitative PCR, Western blot or immunocytochemistry. In response to FSS, Claudin-2 disappeared and ZO-1 displayed punctuated and discontinuous staining in the plasma membrane. Expression of Pard6 was also decreased. Moreover, E-Cadherin abundance was decreased, while its major repressors Snail1 and Snail2 were overexpressed, and β-Catenin staining was disrupted along the cell periphery. Finally, FSS subjected-cells exhibited disappeared primary cilium. Results were confirmed in vivo in a uninephrectomy (8 months) mouse model where increased FSS induced by adaptive hyperfiltration in remnant kidney was accompanied by both decreased epithelial gene expression including ZO-1, E-cadherin and β-Catenin and disappearance of tubular cilia. In conclusion, these results show that proximal tubular cells lose an important number of their epithelial characteristics after long term exposure to FSS both in vitro and in vivo. Thus, the changes in urinary FSS associated with nephropathies should be considered as potential insults for tubular cells leading to disorganization of the tubular epithelium. PMID:26146837

  1. 78 FR 37584 - U.S. Steel Tubular Products, Inc., Mckeesport Tubular Operations Division, Subsidiary of United...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-21

    ... Employment and Training Administration U.S. Steel Tubular Products, Inc., Mckeesport Tubular Operations Division, Subsidiary of United States Steel Corporation, Mckeesport, Pennsylvania; Notice of Amended... workers of U.S. Steel Tubular Products, McKeesport Tubular Operations Division, a subsidiary of...

  2. CD36 mediates proximal tubular binding and uptake of albumin and is upregulated in proteinuric nephropathies.

    PubMed

    Baines, Richard J; Chana, Ravinder S; Hall, Matthew; Febbraio, Maria; Kennedy, David; Brunskill, Nigel J

    2012-10-01

    Dysregulation of renal tubular protein handling in proteinuria contributes to the development of chronic kidney disease. We investigated the role of CD36 as a novel candidate mediator of albumin binding and endocytosis in the kidney proximal tubule using both in vitro and in vivo approaches, and in nephrotic patient renal biopsy samples. In CD36-transfected opossum kidney proximal tubular cells, both binding and uptake of albumin were substantially enhanced. A specific CD36 inhibitor abrogated this effect, but receptor-associated protein, which blocks megalin-mediated endocytosis of albumin, did not. Mouse proximal tubular cells expressed CD36 and this was absent in CD36 null animals, whereas expression of megalin was equal in these animals. Compared with wild-type mice, CD36 null mice demonstrated a significantly increased urinary protein-to-creatinine ratio and albumin-to-creatinine ratio. Proximal tubular cells expressed increased CD36 when exposed to elevated albumin concentrations in culture medium. Expression of CD36 was studied in renal biopsy tissue obtained from adult patients with heavy proteinuria due to minimal change disease, membranous nephropathy, or focal segmental glomerulosclerosis. Proximal tubular CD36 expression was markedly increased in proteinuric individuals. We conclude that CD36 is a novel mediator influencing binding and uptake of albumin in the proximal tubule that is upregulated in proteinuric renal diseases. CD36 may represent a potential therapeutic target in proteinuric nephropathy. PMID:22791331

  3. Osteoprotegerin in Exosome-Like Vesicles from Human Cultured Tubular Cells and Urine

    PubMed Central

    Benito-Martin, Alberto; Ucero, Alvaro Conrado; Zubiri, Irene; Posada-Ayala, Maria; Fernandez-Fernandez, Beatriz; Cannata-Ortiz, Pablo; Sanchez-Nino, Maria Dolores; Ruiz-Ortega, Marta; Egido, Jesus; Alvarez-Llamas, Gloria; Ortiz, Alberto

    2013-01-01

    Urinary exosomes have been proposed as potential diagnostic tools. TNF superfamily cytokines and receptors may be present in exosomes and are expressed by proximal tubular cells. We have now studied the expression of selected TNF superfamily proteins in exosome-like vesicles from cultured human proximal tubular cells and human urine and have identified additional proteins in these vesicles by LC-MS/MS proteomics. Human proximal tubular cells constitutively released exosome-like vesicles that did not contain the TNF superfamily cytokines TRAIL or TWEAK. However, exosome-like vesicles contained osteoprotegerin (OPG), a TNF receptor superfamily protein, as assessed by Western blot, ELISA or selected reaction monitoring by nLC-(QQQ)MS/MS. Twenty-one additional proteins were identified in tubular cell exosome-like vesicles, including one (vitamin D binding protein) that had not been previously reported in exosome-like vesicles. Twelve were extracellular matrix proteins, including the basement membrane proteins type IV collagen, nidogen-1, agrin and fibulin-1. Urine from chronic kidney disease patients contained a higher amount of exosomal protein and exosomal OPG than urine from healthy volunteers. Specifically OPG was increased in autosomal dominant polycystic kidney disease urinary exosome-like vesicles and expressed by cystic epithelium in vivo. In conclusion, OPG is present in exosome-like vesicles secreted by proximal tubular epithelial cells and isolated from Chronic Kidney Disease urine. PMID:24058411

  4. Three-dimensional nanotube electrode arrays for hierarchical tubular structured high-performance pseudocapacitors

    NASA Astrophysics Data System (ADS)

    Gao, Yuan; Lin, Yuanjing; Chen, Jiaqi; Lin, Qingfeng; Wu, Yue; Su, Wenjun; Wang, Wenli; Fan, Zhiyong

    2016-07-01

    Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with high uniformity. The large surface area of such a structure leads to remarkable surface area enhancement up to 51.8 times compared to a planar structure. Combining with electrochemically deposited manganese dioxide (MnO2) nanoflakes on the inner side wall of the FTO nanotubes, the unique hierarchical tubular structured pseudocapacitor electrode demonstrated the highest areal capacitance of 193.8 mF cm-2 at the scan rate of 5 mV s-1 and 184 mF cm-2 at the discharge current density of 0.6 mA cm-2, which is 18.5 times that of a planar electrode. And it also showed a volumetric capacitance of 112.6 F cm-3 at the scan rate of 5 mV s-1 and 108.8 F cm-3 at the discharge current density of 0.6 mA cm-2. In addition, the cyclic stability test also indicated that a nanostructured pseudocapacitive electrode has a much larger capacitance retention after 3000 cycles of the charge-discharge process compared with a planar electrode, primarily due to the mechanical stability of the nanostructure. Moreover, pseudocapacitor device fabrication based on such electrodes shows the volumetric capacitance of 17.5 F cm-3, and the highest specific energy of 1.56 × 10-3 Wh cm-3. With the merit of facile fabrication procedures and largely enhanced electrochemical performance, such a 3-D structure has high potency for energy storage systems for a wide range of practical applications.Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with

  5. Glutamatergic Signaling Maintains the Epithelial Phenotype of Proximal Tubular Cells

    PubMed Central

    Bozic, Milica; de Rooij, Johan; Parisi, Eva; Ortega, Marta Ruiz; Fernandez, Elvira

    2011-01-01

    Epithelial–mesenchymal transition (EMT) contributes to the progression of renal tubulointerstitial fibrosis. The N-methyl-d-aspartate receptor (NMDAR), which is present in proximal tubular epithelium, is a glutamate receptor that acts as a calcium channel. Activation of NMDAR induces actin rearrangement in cells of the central nervous system, but whether it helps maintain the epithelial phenotype of the proximal tubule is unknown. Here, knockdown of NMDAR1 in a proximal tubule cell line (HK-2) induced changes in cell morphology, reduced E-cadherin expression, and increased α-SMA expression. Induction of EMT with TGF-β1 led to downregulation of both E-cadherin and membrane-associated β-catenin, reorganization of F-actin, expression of mesenchymal markers de novo, upregulation of Snail1, and increased cell migration; co-treatment with NMDA attenuated all of these changes. Furthermore, NMDA reduced TGF-β1–induced phosphorylation of Erk1/2 and Akt and the activation of Ras, suggesting that NMDA antagonizes TGF-β1–induced EMT by inhibiting the Ras-MEK pathway. In the unilateral ureteral obstruction model, treatment with NMDA blunted obstruction-induced upregulation of α-SMA, FSP1, and collagen I and downregulation of E-cadherin. Taken together, these results suggest that NMDAR plays a critical role in preserving the normal epithelial phenotype and modulating tubular EMT. PMID:21597037

  6. Salicylate-induced proximal tubular dysfunction.

    PubMed

    Tsimihodimos, Vasilis; Psychogios, Nikolaos; Kakaidi, Varvara; Bairaktari, Eleni; Elisaf, Moses

    2007-09-01

    We describe the case of a 17-year-old girl who was admitted to our clinic for drug poisoning. Twelve hours after the ingestion of 25 tablets of aspirin (12.5 g of acetylsalicylic acid), the patient had a generalized proximal tubular dysfunction characterized by glucosuria (in the face of normal serum glucose levels), proteinuria, and uric acid wasting. Further characterization of the tubular dysfunction using high-resolution proton nuclear magnetic resonance spectroscopy of the urine showed a pattern consistent with proximal tubular injury. An important characteristic of the salicylate-induced proximal tubular dysfunction in our patient was its rapid reversibility. A trend toward normalization of fractional excretion values of electrolytes was observed 2 days after ingestion. Determination of serum and urine metabolites and spectroscopy of urine 15 days later showed no evidence of tubular dysfunction. The mechanisms potentially implicated in the pathogenesis of salicylate-induced Fanconi syndrome are discussed and a brief review of the relevant literature is provided. PMID:17720526

  7. How bio-filaments twist membranes.

    PubMed

    Fierling, Julien; Johner, Albert; Kulić, Igor M; Mohrbach, Hervé; Müller, Martin Michael

    2016-06-29

    We study the deformations of a fluid membrane imposed by adhering stiff bio-filaments due to the torques they apply. In the limit of small deformations, we derive a general expression for the energy and the deformation field of the membrane. This expression is specialised to different important cases including closed and helical bio-filaments. In particular, we analyse interface-mediated interactions and membrane wrapping when the filaments apply a local torque distribution on a tubular membrane. PMID:27291854

  8. A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes

    NASA Astrophysics Data System (ADS)

    Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

    2015-12-01

    Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

  9. A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes.

    PubMed

    Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

    2015-12-01

    Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well. PMID:26706687

  10. Concurrent feline immune-complex nephritis. Tubular antigen-positive and renal amyloidosis.

    PubMed

    Saegusa, S; Shimizu, F; Nagase, M; Kasegawa, A

    1979-08-01

    We describe tubular antigen-positive immune-complex nephritis in a case of feline renal amyloidosis. Amyloid deposition was observed in mesangial area, and thickening of capillary walls was shown in the majority of the glomeruli. This case was also characterized with typical fluorescent granular depositions of cat IgG and C3 along the glomerular capillary walls as seen in human membranous glomerulonephritis. The fluorescent pattern of tubular antigen was identical with that of IgG and C3. Electron micrograph showed the thickening and irregularity of glomerular basement membranes, fusion of foot processes, and deposits of electron-dense or sometimes translucent materials, mostly in the intramembranous location. The causal sequence of the coincidental deposition of amyloid and immune complexes is discussed. PMID:157110

  11. Tubular Colonic Duplication Presenting as Rectovestibular Fistula

    PubMed Central

    Bendre, Pradnya; D'souza, Flavia; Ramchandra, Mukunda; Nage, Amol; Palse, Nitin

    2015-01-01

    Complete colonic duplication is a very rare congenital anomaly that may have different presentations according to its location and size. Complete colonic duplication can occur in about 15% of all gastrointestinal duplications. Double termination of tubular colonic duplication in the perineum is even more uncommon. We present a case of a Y-shaped tubular colonic duplication which presented with a rectovestibular fistula and a normal anus. Radiological evaluation and initial exploration for sigmoidostomy revealed duplicated colons with a common vascular supply. Endorectal mucosal resection of theduplicated distal segment till the colostomy site with division of the septum of the proximal segment and colostomy closure proved curative without compromise of the continence mechanism. Tubular colonic duplication should always be ruled out when a diagnosis of perineal canal is considered in cases of vestibular fistula alongwith a normal anus. PMID:26473141

  12. Tubular Colonic Duplication Presenting as Rectovestibular Fistula.

    PubMed

    Karkera, Parag J; Bendre, Pradnya; D'souza, Flavia; Ramchandra, Mukunda; Nage, Amol; Palse, Nitin

    2015-09-01

    Complete colonic duplication is a very rare congenital anomaly that may have different presentations according to its location and size. Complete colonic duplication can occur in about 15% of all gastrointestinal duplications. Double termination of tubular colonic duplication in the perineum is even more uncommon. We present a case of a Y-shaped tubular colonic duplication which presented with a rectovestibular fistula and a normal anus. Radiological evaluation and initial exploration for sigmoidostomy revealed duplicated colons with a common vascular supply. Endorectal mucosal resection of theduplicated distal segment till the colostomy site with division of the septum of the proximal segment and colostomy closure proved curative without compromise of the continence mechanism. Tubular colonic duplication should always be ruled out when a diagnosis of perineal canal is considered in cases of vestibular fistula alongwith a normal anus. PMID:26473141

  13. Tubular solid oxide fuel cell current collector

    DOEpatents

    Bischoff, Brian L.; Sutton, Theodore G.; Armstrong, Timothy R.

    2010-07-20

    An internal current collector for use inside a tubular solid oxide fuel cell (TSOFC) electrode comprises a tubular coil spring disposed concentrically within a TSOFC electrode and in firm uniform tangential electrical contact with the electrode inner surface. The current collector maximizes the contact area between the current collector and the electrode. The current collector is made of a metal that is electrically conductive and able to survive under the operational conditions of the fuel cell, i.e., the cathode in air, and the anode in fuel such as hydrogen, CO, CO.sub.2, H.sub.2O or H.sub.2S.

  14. Deployable and retractable telescoping tubular structure development

    NASA Technical Reports Server (NTRS)

    Thomson, M. W.

    1994-01-01

    A new deployable and retractable telescoping boom capable of high deployed stiffness and strength is described. Deployment and retraction functions are controlled by simple, reliable, and fail-safe latches between the tubular segments. The latch and a BI-STEM (Storable Tubular Extendible Member) actuator work together to eliminate the need for the segments to overlap when deployed. This yields an unusually lightweight boom and compact launch configuration. An aluminum space-flight prototype with three joints displays zero structural deadband, low hysteresis, and high damping. The development approach and difficulties are discussed. Test results provide a joint model for sizing flight booms of any diameter and length.

  15. Fabrication of Pd Micro-Membrane Supported on Nano-Porous Anodized Aluminum Oxide for Hydrogen Separation.

    PubMed

    Kim, Taegyu

    2015-08-01

    In the present study, nano-porous anodized aluminum oxide (AAO) was used as a support of the Pd membrane. The AAO fabrication process consists of an electrochemical polishing, first/second anodizing, barrier layer dissolving and pores widening. The Pd membrane was deposited on the AAO support using an electroless plating with ethylenediaminetetraacetic acid (EDTA) as a plating agent. The AAO had the regular pore structure with the maximum pore diameter of ~100 nm so it had a large opening area but a small free standing area. The 2 µm-thick Pd layer was obtained by the electroless plating for 3 hours. The Pd layer thickness increased with increasing the plating time. However, the thickness was limited to ~5 µm in maximum. The H2 permeation flux was 0.454 mol/m2-s when the pressure difference of 66.36 kPa0.5 was applied at the Pd membrane under 400 °C. PMID:26369167

  16. Changes of bacterial diversity and tetracycline resistance in sludge from AAO systems upon exposure to tetracycline pressure.

    PubMed

    Huang, Manhong; Qi, Fangfang; Wang, Jue; Xu, Qi; Lin, Li

    2015-11-15

    Two lab-scale anaerobic-anoxic-oxic (AAO) systems were used to investigate the changes in tetracycline (TC) resistance and bacterial diversity upon exposure to TC pressure. High-throughput sequencing was used to detect diversity changes in microorganisms at the level of class in sludge from different bioreactors with and without TC. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect the abundances of eight tetracycline resistance genes (TRGs), tetA, tetB, tetC, tetE, tetM, tetO, tetS and tetX. The results showed that the diversities of the microbial communities of anoxic, anaerobic and aerobic sludge all increased with the addition of TC. TC substantially changed the structure of the microbial community regardless of oxygen conditions. Bacteroidetes and Proteobacteria were the dominant species in the three kinds of sludge and were substantially enriched with TC pressure. In sludge with TC added, almost all target TRGs proliferated more than those in sludge without TC except tetX, which decreased in anaerobic sludge with TC addition. The concentration of efflux pump genes, tet(A-C, E), was the highest among the three groups of TRGs in the different kinds of sludge. PMID:26079369

  17. Micro/nano-hybrid lens for enhancing light extraction using micro-milling and anodic aluminium oxide (AAO)

    NASA Astrophysics Data System (ADS)

    Kim, Shin Hyeong; Kim, Min Gu; Kang, Jeong Jin; Lee, Pyeong An; Kim, Bo Hyun; Cho, Young Hak

    2016-01-01

    In the recent past there has been much research towards increasing the transmission of light in optical systems by reducing the Fresnel reflection of radiation, as the reflection of light from surfaces seriously decreases the performance of an optical device. These drawbacks have been overcome by mainly two methods, which are anti-reflective coating and anti-reflective nanostructure formation. In this study, we developed a simple fabrication process for Al micro/nano hybrid lens (MNHL) moulds for efficient light extraction using micro-milling and anodic aluminum oxide (AAO). From these moulds, two different types of polymer MNHL were fabricated using hot-embossing; one was a polymer MNHL that was covered with nanostructures over the entire surface, and the other was one for which only the microlens surface was covered with nanostructures. Two different types of polymer MNHLs were evaluated and compared with each other concerning the light extraction performance. The MNHL with nanostructures only on the microlens surface exhibited a higher light extraction performance than the other by 20.7%. It is expected that the fabricated MNHL can be used for the amplification of small signals when observing the presence of bio-molecules dyed with a fluorescent material.

  18. Structural influence on Raman scattering of a new C60 thin film prepared by AAO template with the method of pressure difference.

    PubMed

    Zhixun, Luo; Yan, Fang

    2006-01-01

    An anodic aluminum oxide (AAO) template is prepared by anodizing aluminum in oxalic acid solution. C60 crystals were grown, using the pressure difference method, in the pores of the template, representing a brushlike thin film layer with a honeycomb boundary structure in one side and nail arrays in the other side. Different Raman spectra of the C60 thin film from the both sides are presented, which indicate the different uniformly ordered structure character and the interface behavior of the C60 film on the surface with C60 crystals in the AAO nanopores. On the basis of energy and group theory, the strengthening of the Raman intensity and the broadening of Raman modes may imply that more transition spectral lines between vibration or rotation energy levels of C60 molecules were excited and detected. PMID:16827561

  19. Direct emissions of N2O, CO 2, and CH 4 from A/A/O bioreactor systems: impact of influent C/N ratio.

    PubMed

    Ren, Yangang; Wang, Jinhe; Xu, Li; Liu, Cui; Zong, Ruiqiang; Yu, Jianlin; Liang, Shuang

    2015-06-01

    Direct emissions of N2O, CO2, and CH4, three important greenhouse gases (GHGs), from biological sewage treatment process have attracted increasing attention worldwide, due to the increasing concern about climate change. Despite the tremendous efforts devoted to understanding GHG emission from biological sewage treatment process, the impact of influent C/N ratios, in terms of chemical oxygen demand (COD)/total nitrogen (TN), on an anaerobic/anoxic/oxic (A/A/O) bioreactor system has not been investigated. In this work, the direct GHG emission from A/A/O bioreactor systems fed with actual sewage was analyzed under different influent C/N ratios over a 6-month period. The results showed that the variation in influent carbon (160 to 500 mg/L) and nitrogen load (35 to 95 mg/L) dramatically influenced pollutant removal efficiency and GHG production from this process. In the A/A/O bioreactor systems, the GHG production increased from 26-39 to 112-173 g CO2-equivalent as influent C/N ratios decreased from 10.3/10.7 to 3.5/3.8. Taking consideration of pollutant removal efficiency and direct biogenic GHG (N2O, CO2, and CH4) production, the optimum influent C/N ratio was determined to be 7.1/7.5, at which a relatively high pollutant removal efficiency and meanwhile a low level of GHG production (30.4 g CO2-equivalent) can be achieved. Besides, mechanical aeration turned out to be the most significant factor influencing GHG emission from the A/A/O bioreactor systems. PMID:25850740

  20. Ag-nanoparticles-decorated NiO-nanoflakes grafted Ni-nanorod arrays stuck out of porous AAO as effective SERS substrates.

    PubMed

    Zhou, Qitao; Meng, Guowen; Huang, Qing; Zhu, Chuhong; Tang, Haibin; Qian, Yiwu; Chen, Bin; Chen, Bensong

    2014-02-28

    NiO-nanoflakes (NiO-NFs) grafted Ni-nanorod (Ni-NR) arrays stuck out of the porous anodic aluminum oxide (AAO) template are achieved by a combinatorial process of AAO-confined electrodeposition of Ni-NRs, selectively etching part of the AAO template to expose the Ni-NRs, wet-etching the exposed Ni-NRs in ammonia to obtain Ni(OH)2-NFs grafted onto the cone-shaped Ni-NRs, and annealing to transform Ni(OH)2-NFs in situ into NiO-NFs. By top-view sputtering, Ag-nanoparticles (Ag-NPs) are decorated on each NiO-NFs grafted Ni-NR (denoted as NiO-NFs@Ni-NR). The resultant Ag-NPs-decorated NiO-NFs@Ni-NR (denoted as Ag-NPs@NiO-NFs@Ni-NR) arrays exhibit not only strong surface-enhanced Raman scattering (SERS) activity but also reproducible SERS-signals over the whole array. It is demonstrated that the strong SERS-activity is mainly ascribed to the high density of sub-10 nm gaps (hot spots) between the neighboring Ag-NPs, the semiconducting NiO-NFs induced chemical enhancement effect, and the lightning rod effect of the cone-shaped Ni-NRs. The three-level hierarchical nanostructure arrays stuck out of the AAO template can be utilized to probe polychlorinated biphenyls (PCBs, a kind of global environmental hazard) with a concentration as low as 5 × 10(-6) M, showing promising potential in SERS-based rapid detection of organic environmental pollutants. PMID:24419246

  1. Familial myopathy with tubular aggregates associated with abnormal pupils.

    PubMed

    Shahrizaila, Nortina; Lowe, James; Wills, Adrian

    2004-09-28

    The authors describe familial tubular aggregate myopathy associated with abnormal pupils. Four family members from two generations had myopathy and pupillary abnormalities. The myopathologic findings consisted of tubular aggregates in many fibers but predominantly type I fibers. PMID:15452313

  2. Epidermal growth factor attenuates tubular necrosis following mercuric chloride damage by regeneration of indigenous, not bone marrow-derived cells

    PubMed Central

    Yen, Tzung-Hai; Alison, Malcolm R; Goodlad, Robert A; Otto, William R; Jeffery, Rosemary; Cook, H Terence; Wright, Nicholas A; Poulsom, Richard

    2015-01-01

    To assess effects of epidermal growth factor (EGF) and pegylated granulocyte colony-stimulating factor (P-GCSF; pegfilgrastim) administration on the cellular origin of renal tubular epithelium regenerating after acute kidney injury initiated by mercuric chloride (HgCl2). Female mice were irradiated and male whole bone marrow (BM) was transplanted into them. Six weeks later recipient mice were assigned to one of eight groups: control, P-GCSF+, EGF+, P-GCSF+EGF+, HgCl2, HgCl2+P-GCSF+, HgCl2+EGF+ and HgCl2+P-GCSF+EGF+. Following HgCl2, injection tubular injury scores increased and serum urea nitrogen levels reached uraemia after 3 days, but EGF-treated groups were resistant to this acute kidney injury. A four-in-one analytical technique for identification of cellular origin, tubular phenotype, basement membrane and S-phase status revealed that BM contributed 1% of proximal tubular epithelium in undamaged kidneys and 3% after HgCl2 damage, with no effects of exogenous EGF or P-GCSF. Only 0.5% proximal tubular cells were seen in S-phase in the undamaged group kidneys; this increased to 7–8% after HgCl2 damage and to 15% after addition of EGF. Most of the regenerating tubular epithelium originated from the indigenous pool. BM contributed up to 6.6% of the proximal tubular cells in S-phase after HgCl2 damage, but only to 3.3% after additional EGF. EGF administration attenuated tubular necrosis following HgCl2 damage, and the major cause of this protective effect was division of indigenous cells, whereas BM-derived cells were less responsive. P-GCSF did not influence damage or regeneration. PMID:25389045

  3. Effect of various de-anodizing techniques on the surface stability of non-colored and colored nanoporous AAO films in acidic solution

    NASA Astrophysics Data System (ADS)

    Awad, Ahmed M.; Shehata, Omnia S.; Heakal, Fakiha El-Taib

    2015-12-01

    Anodic aluminum oxide (AAO) is well known as an important nanostructured material, and a useful template in the fabrication of nanostructures. Nanoporous anodic alumina (PAA) with high open porosity was prepared by adopting three de-anodizing regimes following the first anodizing step and preceding the second one. The de-anodizing methods include electrolytic etching (EE) and chemical etching using either phosphoric acid (PE) or sodium hydroxide (HE) solutions. Three of the obtained AAO samples were black colored by electrodeposition of copper nanoparticles in their pores. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used to characterize the electrochemical performance of the two sets of the prepared samples. In general, the data obtained in aggressive aerated 0.5 M HCl solution demonstrated dissimilar behavior for the three prepared samples despite that the second anodizing step was the same for all of them. The data indicated that the resistance and thickness of the inner barrier part of nano-PAA film, are the main controlling factors determining its stability. On the other hand, coloring the film decreased its stability due to the galvanic effect. The difference in the electrochemical behavior of the three colored samples was discussed based on the difference in both the pore size and thickness of the outer porous part of PAA film as supported by SEM, TEM and cross-sectional micrographs. These results can thus contribute for better engineering applications of nanoporous AAO.

  4. SEM and XPS studies of nanohole arrays on InP(1 0 0) surfaces created by coupling AAO templates and low energy Ar + ion sputtering

    NASA Astrophysics Data System (ADS)

    Robert-Goumet, C.; Monier, G.; Zefack, B.; Chelda, S.; Bideux, L.; Gruzza, B.; Awitor, O. K.

    2009-10-01

    The aim of the present study is to demonstrate the feasibility to form well-ordered nanoholes on InP(1 0 0) surfaces by low Ar + ion sputtering process in UHV conditions from anodized aluminum oxide (AAO) templates. This process is a promising approach in creating ordered arrays of surface nanostructures with controllable size and morphology. To follow the Ar + ion sputtering effects on the AAO/InP surfaces, X-ray photoelectron spectroscopy (XPS) was used to determine the different surface species. In 4d and P 2p core level spectra were recorded on different InP(1 0 0) surfaces after ions bombardment. XPS results showed the presence of metallic indium on both smooth InP(1 0 0) and AAO/InP(1 0 0) surfaces. Finally, we showed that this experiment led to the formation of metallic In dropplets about 10 nm in diameter on nanoholes patterned InP surface while the as-received InP(1 0 0) surface generated metallic In about 60 nm in diameter.

  5. Comparative physiology of renal tubular transport mechanisms.

    PubMed Central

    Long, S.; Giebisch, G.

    1979-01-01

    This manuscript discusses current concepts of glomerular filtration and tubular transport of sodium, water, potassium, and urinary acidification by vertebrate kidneys in a comparative context. Work in mammalian and amphibian nephrons receives major emphasis due to our interest in application of new techniques for investigation of cellular mechanisms; when available, data from other vertebrate classes are discussed. Images FIG. 3 PMID:395765

  6. [Hypokalemic pareses secondary to renal tubular acidosis].

    PubMed

    Gøransson, L G; Apeland, T; Omdal, R

    2000-01-30

    A 24 year old woman presented with flaccid paralysis, severe hypokalaemia and hyperchloremia, metabolic acidosis. Immunological tests and labial glandular biopsy indicated primary Sjögren's syndrome as the underlying cause of her distal renal tubular acidosis. The patient recovered after alkali and potassium substitution and was put on oral treatment with potassium citrate. PMID:10827521

  7. Tubular copper thrust chamber design study

    NASA Technical Reports Server (NTRS)

    Masters, A. I.; Galler, D. E.

    1992-01-01

    The use of copper tubular thrust chambers is particularly important in high performance expander cycle space engines. Tubular chambers have more surface area than flat wall chambers, and this extra surface area provides enhanced heat transfer for additional energy to power the cycle. This paper was divided into two sections: (1) a thermal analysis and sensitivity study; and (2) a preliminary design of a selected thrust chamber configuration. The thermal analysis consisted of a statistical optimization to determine the optimum tube geometry, tube booking, thrust chamber geometry, and cooling routing to achieve the maximum upper limit chamber pressure for a 25,000 pound thrust engine. The preliminary design effort produced a layout drawing of a tubular thrust chamber that is three inches shorter than the Advanced Expander Test Bed (AETB) milled channel chamber but is predicted to provide a five percent increase in heat transfer. Testing this chamber in the AETB would confirm the inherent advantages of tubular chamber construction and heat transfer.

  8. PROGRESS REPORT OF FY 2004 ACTIVITIES: IMPROVED WATER VAPOR AND CLOUD RETRIEVALS AT THE NSA/AAO

    SciTech Connect

    E. R. Westwater; V. V. Leuskiy; M. Klein; A. J. Gasiewski; and J. A. Shaw

    2004-11-01

    The basic goals of the research are to develop and test algorithms and deploy instruments that improve measurements of water vapor, cloud liquid, and cloud coverage, with a focus on the Arctic conditions of cold temperatures and low concentrations of water vapor. The importance of accurate measurements of column amounts of water vapor and cloud liquid has been well documented by scientists within the Atmospheric Radiation Measurement Program. Although several technologies have been investigated to measure these column amounts, microwave radiometers (MWR) have been used operationally by the ARM program for passive retrievals of these quantities: precipitable water vapor (PWV) and integrated water liquid (IWL). The technology of PWV and IWL retrievals has advanced steadily since the basic 2-channel MWR was first deployed at ARM CART sites Important advances are the development and refinement of the tipcal calibration method [1,2], and improvement of forward model radiative transfer algorithms [3,4]. However, the concern still remains that current instruments deployed by ARM may be inadequate to measure low amounts of PWV and IWL. In the case of water vapor, this is especially important because of the possibility of scaling and/or quality control of radiosondes by the water amount. Extremely dry conditions, with PWV less than 3 mm, commonly occur in Polar Regions during the winter months. Accurate measurements of the PWV during such dry conditions are needed to improve our understanding of the regional radiation energy budgets. The results of a 1999 experiment conducted at the ARM North Slope of Alaska/Adjacent Arctic Ocean (NSA/AAO) site during March of 1999 [5] have shown that the strength associated with the 183 GHz water vapor absorption line makes radiometry in this frequency regime suitable for measuring low amounts of PWV. As a portion of our research, we conducted another millimeter wave radiometric experiment at the NSA/AAO in March-April 2004. This

  9. 78 FR 14361 - U.S. Steel Tubular Products, Inc., Mckeesport Tubular Operations Division, Subsidiary of United...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... Employment and Training Administration U.S. Steel Tubular Products, Inc., Mckeesport Tubular Operations Division, Subsidiary of United States Steel Corporation, Mckeesport, PA; Notice of Initiation of...) filed on December 20, 2012 on behalf of workers of U.S. Steel Tubular Products, McKeesport...

  10. Renal tubular acidosis complicated with hypokalemic periodic paralysis.

    PubMed

    Chang, Y C; Huang, C C; Chiou, Y Y; Yu, C Y

    1995-07-01

    Three Chinese girls with hypokalemic periodic paralysis secondary to different types of renal tubular acidosis are presented. One girl has primary distal renal tubular acidosis complicated with nephrocalcinosis. Another has primary Sjögren syndrome with distal renal tubular acidosis, which occurs rarely with hypokalemic periodic paralysis in children. The third has an isolated proximal renal tubular acidosis complicated with multiple organ abnormalities, unilateral carotid artery stenosis, respiratory failure, and consciousness disturbance. The diagnostic evaluation and emergent and prophylactic treatment for these three types of renal tubular acidosis are discussed. PMID:7575850

  11. Pattern Selection in Growing Tubular Tissues

    NASA Astrophysics Data System (ADS)

    Ciarletta, P.; Balbi, V.; Kuhl, E.

    2014-12-01

    Tubular organs display a wide variety of surface morphologies including circumferential and longitudinal folds, square and hexagonal undulations, and finger-type protrusions. Surface morphology is closely correlated to tissue function and serves as a clinical indicator for physiological and pathological conditions, but the regulators of surface morphology remain poorly understood. Here, we explore the role of geometry and elasticity on the formation of surface patterns. We establish morphological phase diagrams for patterns selection and show that increasing the thickness or stiffness ratio between the outer and inner tubular layers induces a gradual transition from circumferential to longitudinal folding. Our results suggest that physical forces act as regulators during organogenesis and give rise to the characteristic circular folds in the esophagus, the longitudinal folds in the valves of Kerckring, the surface networks in villi, and the crypts in the large intestine.

  12. Tubular lap joints for wind turbine applications

    SciTech Connect

    Reedy, E.D. Jr.; Guess, T.R.

    1990-01-01

    A combined analytical/experimental study of the strength of thick- walled, adhesively bonded PMMA-to-aluminum and E-glass/epoxy composite-to-aluminum tubular lap joints under axial load has been conducted. Test results include strength and failure mode data. Moreover, strain gages placed along the length of the outer tubular adherend characterize load transfer from one adherend to the other. The strain gage data indicate that load transfer is nonuniform and that the relatively compliant PMMA has the shorter load transfer length. Strains determined by a finite element analysis of the tested joints are in excellent agreement with those measured. Calculated bond stresses are highest in the region of observed failure, and extensive bond yielding is predicted in the E- glass/epoxy composite-to-aluminum joint prior to joint failure. 4 refs., 13 figs., 1 tab.

  13. Tubular Heart Pumping Mechanisms in Ciona Intestinalis

    NASA Astrophysics Data System (ADS)

    Battista, Nicholas; Miller, Laura

    2015-11-01

    In vertebrate embryogenesis, the first organ to form is the heart, beginning as a primitive heart tube. However, many invertebrates have tubular hearts from infancy through adulthood. Heart tubes have been described as peristaltic and impedance pumps. Impedance pumping assumes a single actuation point of contraction, while traditional peristalsis assumes a traveling wave of actuation. In addition to differences in flow, this inherently implies differences in the conduction system. It is possible to transition from pumping mechanism to the other with a change in the diffusivity of the action potential. In this work we consider the coupling between the fluid dynamics and electrophysiology of both mechanisms, within a basal chordate, the tunicate. Using CFD with a neuro-mechanical model of tubular pumping, we discuss implications of the both mechanisms. Furthermore, we discuss the implications of the pumping mechanism on evolution and development.

  14. Glomerular tubular balance: mediation by luminal hypotonicity.

    PubMed

    Häberle, D A; Müller, U; Nagel, W

    1989-01-01

    Late proximal rat tubular segments were microperfused with slightly hypo- or hypertonic artificial late proximal tubular fluid (ATF) at low (11-13 nl/min) or high (30-38 nl/min) perfusion rates. Volume reabsorption, net chloride and solute reabsorption were measured as a function of length. In addition, the transepithelial resistance and voltage (Vte) were measured as a function of the applied osmotic gradient. Hypertonic solutions equilibrated to isotonicity by solute outflow rather than water influx. With hypertonic ATF the lumen positive Vte was decreased compared with free flow or with hypotonic ATF. The resistance was not significantly different between the different groups. In contrast to hypotonic ATF, hypertonic or isotonic ATF was not significantly reabsorbed. In addition, hypotonic ATF maintained its hypotonicity along the perfused segments. Its reabsorption was flow-dependent. Hypotonicity appeared to enhance solute reabsorption. PMID:2725432

  15. Latch ring for connecting tubular member

    SciTech Connect

    Milberger, L.J.

    1991-06-04

    This patent describes a device for releasably locking an inner member well bore of a tubular outer member, comprising a combination of a grooved inner member profile formed on the exterior of the inner member; a grooved outer member profile formed in the bore of the outer member; a split ring carried by the inner member the ring having a grooved outer profile on its exterior mates with the outer member profile; and the inner member being axially movable.

  16. Tubular electric heater with a thermocouple assembly

    DOEpatents

    House, R.K.; Williams, D.E.

    1975-08-01

    This patent relates to a thermocouple or other instrumentation which is installed within the walls of a tubular sheath surrounding a process device such as an electric heater. The sheath comprises two concentric tubes, one or both of which have a longitudinal, concave crease facing the other tube. The thermocouple is fixedly positioned within the crease and the outer tube is mechanically reduced to form an interference fit onto the inner tube. (auth)

  17. Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes

    PubMed Central

    2012-01-01

    Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors. PMID:22731888

  18. Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes

    NASA Astrophysics Data System (ADS)

    Hevia, Samuel; Homm, Pía; Cortes, Andrea; Núñez, Verónica; Contreras, Claudia; Vera, Jenniffer; Segura, Rodrigo

    2012-06-01

    Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors.

  19. Hydrogen-Selective Membrane

    DOEpatents

    Collins, John P.; Way, J. Douglas

    1995-09-19

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 .mu.m but typically less than about 20 .mu.m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m.sup.2.s at a temperature of greater than about 500.degree. C. and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500.degree. C. and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400.degree. C. and less than about 1000.degree. C. before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process.

  20. Hydrogen-selective membrane

    DOEpatents

    Collins, J.P.; Way, J.D.

    1995-09-19

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 {micro}m but typically less than about 20 {micro}m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m{sup 2}s at a temperature of greater than about 500 C and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500 C and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400 C and less than about 1000 C before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process. 9 figs.

  1. Hydrogen-selective membrane

    DOEpatents

    Collins, John P.; Way, J. Douglas

    1997-01-01

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 .mu.m but typically less than about 20 .mu.m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m.sup.2. s at a temperature of greater than about 500.degree. C. and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500.degree. C. and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400.degree. C. and less than about 1000.degree. C. before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process.

  2. Hydrogen-selective membrane

    DOEpatents

    Collins, J.P.; Way, J.D.

    1997-07-29

    A hydrogen-selective membrane comprises a tubular porous ceramic support having a palladium metal layer deposited on an inside surface of the ceramic support. The thickness of the palladium layer is greater than about 10 {micro}m but typically less than about 20 {micro}m. The hydrogen permeation rate of the membrane is greater than about 1.0 moles/m{sup 2} s at a temperature of greater than about 500 C and a transmembrane pressure difference of about 1,500 kPa. Moreover, the hydrogen-to-nitrogen selectivity is greater than about 600 at a temperature of greater than about 500 C and a transmembrane pressure of about 700 kPa. Hydrogen can be separated from a mixture of gases using the membrane. The method may include the step of heating the mixture of gases to a temperature of greater than about 400 C and less than about 1000 C before the step of flowing the mixture of gases past the membrane. The mixture of gases may include ammonia. The ammonia typically is decomposed to provide nitrogen and hydrogen using a catalyst such as nickel. The catalyst may be placed inside the tubular ceramic support. The mixture of gases may be supplied by an industrial process such as the mixture of exhaust gases from the IGCC process. 9 figs.

  3. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M; Kromer, Brian R; Litwin, Michael M; Rosen, Lee J; Christie, Gervase Maxwell; Wilson, Jamie R; Kosowski, Lawrence W; Robinson, Charles

    2014-01-07

    A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.

  4. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  5. A simple auxetic tubular structure with tuneable mechanical properties

    NASA Astrophysics Data System (ADS)

    Ren, Xin; Shen, Jianhu; Ghaedizadeh, Arash; Tian, Hongqi; Xie, Yi Min

    2016-06-01

    Auxetic materials and structures are increasingly used in various fields because of their unusual properties. Auxetic tubular structures have been fabricated and studied due to their potential to be adopted as oesophageal stents where only tensile auxetic performance is required. However, studies on compressive mechanical properties of auxetic tubular structures are limited in the current literature. In this paper, we developed a simple tubular structure which exhibits auxetic behaviour in both compression and tension. This was achieved by extending a design concept recently proposed by the authors for generating 3D metallic auxetic metamaterials. Both compressive and tensile mechanical properties of the auxetic tubular structure were investigated. It was found that the methodology for generating 3D auxetic metamaterials could be effectively used to create auxetic tubular structures as well. By properly adjusting certain parameters, the mechanical properties of the designed auxetic tubular structure could be easily tuned.

  6. Hyaluronan in Tubular and Interstitial Nephrocalcinosis

    NASA Astrophysics Data System (ADS)

    Verkoelen, Carl F.

    2007-04-01

    Hyaluronan (HA) is the major glycosaminoglycan (GAG) component of the renal medullary interstitium. HA is extremely large (up to 104 kDa) and composed of thousands repeating disaccharides of glucuronic acid (GlcUA) and N-acetylglucosamine (GlcNAc). HA is synthesized by hyaluronan synthases (HASs) and degraded by hyaluronidases (Hyals). The production of HA by renomedullary interstitial cells is mediated by local osmolality. When excess water needs to be excreted, increased interstitial HA seems to antagonize water reabsorption, while the opposite occurs during water conservation. Hence, papillary interstitial HA is low and Hyal high during anti-diuresis, whereas during diuresis HA is high and Hyal low. The polyanion HA plays a role in the reabsorption of hypotonic fluid by immobilizing cations (Na+) via the carboxylate (COO-) groups of GlcUA. The binding of Ca2+ to anionic HA is probably also responsible for the fact that the papilla does not become a stone despite the extremely high interstitial phosphate and oxalate. HA is also an excellent crystal binding molecule. The expression of HA at the luminal surface of renal tubular cells leads to tubular nephrocalcinosis (tubular NC). Calcium staining methods (Von Kossa, Yasue) demonstrated that crystallization inhibitors cannot avoid the occasional precipitation of calcium phosphate in the papillary interstitium (interstitial NC). These crystals are probably immediately immobilized by the gel-like HA matrix. After ulcerating through the pelvic wall the calcified matrix becomes a Randall's plaque. The attachment of calcium oxalate crystals from the primary urine to plaque may ultimately lead to the development of clinical stones in the renal calyces (nephrolithiasis).

  7. Distal Renal Tubular Acidosis and Calcium Nephrolithiasis

    NASA Astrophysics Data System (ADS)

    Moe, Orson W.; Fuster, Daniel G.; Xie, Xiao-Song

    2008-09-01

    Calcium stones are commonly encountered in patients with congenital distal renal tubular acidosis, a disease of renal acidification caused by mutations in either the vacuolar H+-ATPase (B1 or a4 subunit), anion exchanger-1, or carbonic anhydrase II. Based on the existing database, we present two hypotheses. First, heterozygotes with mutations in B1 subunit of H+-ATPase are not normal but may harbor biochemical abnormalities such as renal acidification defects, hypercalciuria, and hypocitraturia which can predispose them to kidney stone formation. Second, we propose at least two mechanisms by which mutant B1 subunit can impair H+-ATPase: defective pump assembly and defective pump activity.

  8. Advanced beaded and tubular structural panels

    NASA Technical Reports Server (NTRS)

    Musgrove, M. D.; Greene, B. E.

    1975-01-01

    A program to develop lightweight beaded and tubular structural panels is described. Applications include external surfaces, where aerodynamically acceptable, and primary structure protected by heat shields. The design configurations were optimized and selected with a computer code which iterates geometric parameters to satisfy strength, stability, and weight constraints. Methods of fabricating these configurations are discussed. Nondestructive testing produced extensive combined compression, shear, and bending test data on local buckling specimens and large panels. The optimized design concepts offer 25 to 30% weight savings compared to conventional stiffened sheet construction.

  9. Tubular solid oxide fuel cell development program

    SciTech Connect

    1995-08-01

    This paper presents an overview of the Westinghouse Solid Oxide Fuel Cell (SOFC) development activities and current program status. The Westinghouse goal is to develop a cost effective cell that can operate for 50,000 to 100,000 hours. Progress toward this goal will be discussed and test results presented for multiple single cell tests which have now successfully exceeded 56,000 hours of continuous power operation at temperature. Results of development efforts to reduce cost and increase power output of tubular SOFCs are described.

  10. Role of mitochondrial-derived oxidants in renal tubular cell cold storage injury

    PubMed Central

    Mitchell, Tanecia; Saba, Hamida; Laakman, Joe; Parajuli, Nirmala; MacMillan-Crow, Lee Ann

    2013-01-01

    Cold storage (CS) is regarded as a necessary procedure during donation of a deceased donor kidney that helps to optimize organ viability. Increased oxidant generation during both CS as well as during the reperfusion (or rewarming/CS.RW) phase have been suggested to be a major contributor to renal injury; although the source and/or biochemical pathways involved with oxidant production remain unclear. The purpose of this study was to determine if renal tubular mitochondrial superoxide is capable of inducing oxidant production and mitochondrial damage in response to a CS.RW insult. To test the role of mitochondrial superoxide in CS.RW injury, we used rat renal proximal tubular (NRK) cells overexpressing manganese superoxide dismutase (MnSOD), the major mitochondrial antioxidant. Oxidant production, mitochondrial membrane potential, respiratory complex function, and cell death were all altered following exposure of NRK cells to CS.RW. MnSOD overexpression or inhibition of nitric oxide synthase (NOS) provided significant protection against oxidant generation, respiratory complex inactivation, and cell death. These findings implicate mitochondrial superoxide, nitric oxide, and their reaction product, peroxynitrite, as key signaling molecules involved in CS.RW injury of renal tubular cells, and suggest that therapeutic inhibition of these pathways may protect the donor kidney. PMID:20659553

  11. Analysis of an active tubular liquid-feed direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Xu, Chao; Faghri, Amir

    2011-08-01

    A two-dimensional, two-phase, non-isothermal model was developed for an active, tubular, liquid-feed direct methanol fuel cell (DMFC). The liquid-gas, two-phase mass transport in the porous anode and cathode was formulated based on the multi-fluid approach in the porous media. The two-phase mass transport in the anode and cathode channels was modeled using the drift-flux and the homogeneous mist-flow models, respectively. Water and methanol crossovers through the membrane were considered due to the effects of diffusion, electro-osmotic drag, and convection. The model enabled a numerical investigation of the effects of various operating parameters, such as current density, methanol flow rate, and oxygen flow rate, on the mass and heat transport characteristics in the tubular DMFC. It was shown that by choosing a proper tube radius and distance between the adjacent cells, a tubular DMFC stack can achieve a much higher energy density compared to its planar counterpart. The results also showed that a large anode flow rate is needed in order to avoid severe blockage of liquid methanol to the anode electrode due to the gas accumulation in the channel. Besides, lowering the flow rate of either the methanol solution or air can lead to a temperature increase along the flow channel. The methanol and water crossovers are nearly independent of the methanol flow rate and the air flow rate.

  12. Membrane tubulation from giant lipid vesicles in alternating electric fields.

    PubMed

    Antonova, K; Vitkova, V; Meyer, C

    2016-01-01

    We report on the formation of tubular membrane protrusions from giant unilamellar vesicles in alternating electric fields. The construction of the experimental chamber permitted the application of external AC fields with strength of dozens of V/mm and kHz frequency during relatively long time periods (several minutes). Besides the vesicle electrodeformation from quasispherical to prolate ellipsoidal shape, the formation of long tubular membrane protrusions with length of up to several vesicle diameters, arising from the vesicular surface in the field direction, was registered and analyzed. The threshold electric field at which the electro-induced protrusions appeared was lower than the field strengths inducing membrane electroporation. PMID:26871107

  13. The determinants of transverse tubular volume in resting skeletal muscle

    PubMed Central

    Sim, Jingwei; Fraser, James A

    2014-01-01

    The transverse tubular (t)-system of skeletal muscle couples sarcolemmal electrical excitation with contraction deep within the fibre. Exercise, pathology and the composition of the extracellular fluid (ECF) can alter t-system volume (t-volume). T-volume changes are thought to contribute to fatigue, rhabdomyolysis and disruption of excitation–contraction coupling. However, mechanisms that underlie t-volume changes are poorly understood. A multicompartment, history-independent computer model of rat skeletal muscle was developed to define the minimum conditions for t-volume stability. It was found that the t-system tends to swell due to net ionic fluxes from the ECF across the access resistance. However, a stable t-volume is possible when this is offset by a net efflux from the t-system to the cell and thence to the ECF, forming a net ion cycle ECF→t-system→sarcoplasm→ECF that ultimately depends on Na+/K+-ATPase activity. Membrane properties that maximize this circuit flux decrease t-volume, including PNa(t) > PNa(s), PK(t) < PK(s) and N(t) < N(s) [P, permeability; N, Na+/K+-ATPase density; (t), t-system membrane; (s), sarcolemma]. Hydrostatic pressures, fixed charges and/or osmoles in the t-system can influence the magnitude of t-volume changes that result from alterations in this circuit flux. Using a parameter set derived from literature values where possible, this novel theory of t-volume was tested against data from previous experiments where t-volume was measured during manipulations of ECF composition. Predicted t-volume changes correlated satisfactorily. The present work provides a robust, unifying theoretical framework for understanding the determinants of t-volume. PMID:25384782

  14. Preparation and gas separation properties of zeolite T membrane.

    PubMed

    Cui, Ying; Kita, Hidetoshi; Okamoto, Ken-ichi

    2003-09-01

    Zeolite T membranes were synthesized on tubular porous mullite tubes by hydrothermal synthesis. The membranes selectively permeated carbon dioxide from CO2/CH4 and CO2/N2 mixtures with high separation performances, which were due to combined effects of molecular sieving and competitive adsorption. PMID:13678177

  15. 75 FR 3248 - Certain Oil Country Tubular Goods From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-20

    ... the notice in the Federal Register of September 30, 2009 (74 FR 50242). The hearing was held in... COMMISSION Certain Oil Country Tubular Goods From China Determination On the basis of the record \\1... oil country tubular goods (``OCTG''), primarily provided for in subheadings 7304.29, 7305.20, and...

  16. Inductor Hardening for Magnetic-Pulse Treatment of Tubular Parts

    NASA Astrophysics Data System (ADS)

    Kurlaeyv, N. V.; Bobin, K. N.; Ryngach, N. A.; Rakhmyanov, A. Kh.

    2016-04-01

    This paper focuses on the issues of modernization of standardized inductor construction for crimping tubular parts by the pulse electromagnetic field with the aim of increasing reliability of technique and its durability. There is given the description of the pilot model of the composite inductor for crimping tubular parts, as well as the results obtained during its test operation.

  17. A potential platform for developing 3D tubular scaffolds for paediatric organ development.

    PubMed

    de Mel, Achala; Yap, Trixie; Cittadella, Giorgio; Hale, Luke Richard; Maghsoudlou, Panagiotis; de Coppi, Paolo; Birchall, Martin A; Seifalian, Alexander M

    2015-03-01

    Children suffer from damaged or loss of hollow organs i.e. trachea, oesophagus or arteries from birth defects or diseases. Generally these organs possess an outer matrix consisting of collagen, elastin, and cells such as smooth muscle cells (SMC) and a luminal layer consisting of endothelial or epithelial cells, whilst presenting a barrier to luminal content. Tissue engineering research enables the construction of such organs and this study explores this possibility with a bioabsorbable nanocomposite biomaterial, polyhedral oligomeric silsesquioxane poly(ε-caprolactone) urea urethane (POSS-PCL).Our established methods of tubular graft extrusion were modified using a porogen-incorporated POSS-PCL and a new lamination method was explored. Porogen (40, 60 or 105 µm) were introduced to POSS-PCL, which were fabricated into a bilayered, dual topography matching the exterior and luminal interior of tubular organs. POSS-PCL with different amounts of porogen were tested for their suitability as a SMC layer by measuring optimal interactions with human adipose derived stem cells. Angiogenesis potential was tested with the chorioallantoic membrane assay. Tensile strength and burst pressures of bilayared tubular grafts were determined. Scaffolds made with 40 µm porogen demonstrated optimal adipose derived stem cell integration and the scaffolds were able to accommodate angiogenesis. Mechanical properties of the grafts confirmed their potential to match the relevant physiological and biophysical parameters. This study presents a platform for the development of hollow organs for transplantation based on POSS-PCL. These bilayered-tubular structures can be tailor-made for cellular integration and match physico-mechanical properties of physiological systems of interest. More specific luminal cell integration and sources of SMC for the external layer could be further explored. PMID:25737129

  18. Renal tubular acidosis due to the milk-alkali syndrome.

    PubMed

    Rochman, J; Better, O S; Winaver, J; Chaimowitz, C; Barzilai, A; Jacobs, R

    1977-06-01

    A 60-year-old man with a history of excessive ingestion of calcium carbonate presented with azotemia, hypercalcemia and hyperphosphatemia. His acid-base status was initially normal. Following the cessation of calcium carbonate treatment, the hypercalcemia and azotemia disappeared, and the patient was found to be in metabolic acidosis with blunted acid excretion and a urine pH of 6.1. Kidney biopsy showed focal tubular calcification; the tubular damage was apparently caused by hypercalcemia and had resulted in renal tubular acidosis. During the three months of observation since that time there has been a tendecy for spontaneous remission of the renal tubular acidosis. Impaired renal hydrogen ion excretion prevented the development of metabolic alkalosis despite ingestion of alkali initially, and was later responsible for the metabolic acidosis. Renal tubular acidosis occurring as a sequel to the milk-alkali syndrome may aggravate the danger of nephrocalcinosis in this syndrome. PMID:885714

  19. Confined semiflexible biopolymers suppress fluctuations of soft membrane tubes

    NASA Astrophysics Data System (ADS)

    Abel, Steven; Mirzaeifard, Sina

    Membrane nanotubes are tubular membrane structures that contain actin and connect cells over long distances. Disrupting the actin cytoskeleton abrogates membrane nanotubes, making them an interesting model system for studying membrane-biopolymer interactions. In this study, we use Monte Carlo computer simulations to investigate tubular, elastic membrane structures with and without semiflexible polymers confined inside. At small values of membrane bending rigidity, fluid membranes adopt irregular, highly fluctuating shapes while non-fluid membranes maintain extended tube-like structures. With increasing bending rigidity, fluid membranes exhibit a local maximum in specific heat that is coincident with a transition to extended tube-like structures. We further find that confining a semiflexible polymer within a fluid membrane tube suppresses membrane shape fluctuations and reduces the specific heat of the membrane. Polymers with a sufficiently large persistence length can significantly deform the membrane tube, leading to localized bulges in the membrane that accommodate regions in which the polymer forms loops. Analytical calculations of the energies of idealized polymer-membrane configurations provide additional insight into the formation of polymer-induced membrane deformations.

  20. Renal tubular secretion of glutathione (GSH)

    SciTech Connect

    Scott, R.D.; Curthoys, N.P.

    1986-05-01

    The rapid turnover of renal GSH may require its secretion into the tubular lumen. Renal clearance of plasma GSH was measured in rats anesthetized with Inactin and infused with (/sup 3/H)inulin. Renal ..gamma..-glutamyltranspeptidase (..gamma..GT) was then inactivated (> 97%) by infusion of acivicin and samples were collected for 6-7 h. By 4.5 h arterial and urinary GSH increased from 5..mu..M and 1.3 n mol/h to 23 ..mu..M and 2400-7000 nmol/h, respectively. The ratio of urinary GSH to filtered load increased from < 0.01 to 0.7-2.6. When renal GSH was decreased to 30% of normal by pretreating rats with buthionine sulfoximine (BSO), the subsequent inactivation of ..gamma..GT caused only a slight increase in arterial GSH and urinary GSH increased to only 400-600 nmol/h (60-70% of filtered load). The amount of GSH filtered by the kidney was reduced by initially treating a rat with acivicin and 3 h later infusing purified ..gamma..GT (0.2 mg/h) to degrade plasma GSH. Just before infusion of ..gamma..GT, arterial GSH was 23 ..mu..M and urinary GSH was equal to 90% of the filtered load. At 1 h after infusion of ..gamma..GT, arterial GSH decreased to 0.3 ..mu..M, whereas urinary GSH remained elevated (1200-1800 nmol/h) and now equalled 10-20 times the filtered load. When similar experiments were carried out in BSO treated rats, maximal urinary GSH was reduced to 200 nmol/h, a value that was still 10 times the filtered load. Therefore, secreted GSH constitutes a significant portion of the GSH that is normally catabolized within the tubular lumen.

  1. Experimental and Theoretical Studies of Electroosmotic Membrane Micropumps

    NASA Astrophysics Data System (ADS)

    Xu, Zuli; Miao, Jianying; Wang, Ning; Sheng, Ping

    2008-03-01

    Electroosmotic (EO) effect means fluid flow (through a porous medium) induced by an applied electric field E. EO pumps have the advantages of no moving parts and easily-controlled accurate flow rate at low applied voltages. We have fabricated nano-channel EO membrane pumps using anodic aluminum oxide (AAO) as the template [1]. The diameter of the uniform-sized nanochannels can range from 60-300nm, with a membrane thickness of 30-100 microns. The EO effect is enhanced by coating the nano-channels with silica. By using de-ionized water, the nanopump performance is shown to agree reasonably well with the theoretical model, with factors such as the ratio of the double layer thickness to channel diameter, channel geometry, and treatment of the AAO membranes playing important roles. With silica coating to the nanochannels, the nanopump can produce a maximum pressure of 1 atm and a maximum flow rate of 86,000μL/min.cm2 under an applied field of 0.94 V/μm. Besides DI water, the micropumps have also been tested to work well with salt, acid or base solution. [1] J.Y. Miao, Z.L. Xu, X.Y. Zhang, N. Wang, Z.Y. Yang, P. Sheng, submitted to Advanced Materials (Appeared online: 10.1002/adma.200700767).

  2. The swan-neck lesion: proximal tubular adaptation to oxidative stress in nephropathic cystinosis.

    PubMed

    Galarreta, Carolina I; Forbes, Michael S; Thornhill, Barbara A; Antignac, Corinne; Gubler, Marie-Claire; Nevo, Nathalie; Murphy, Michael P; Chevalier, Robert L

    2015-05-15

    Cystinosis is an inherited disorder resulting from a mutation in the CTNS gene, causing progressive proximal tubular cell flattening, the so-called swan-neck lesion (SNL), and eventual renal failure. To determine the role of oxidative stress in cystinosis, histologic sections of kidneys from C57BL/6 Ctns(-/-) and wild-type mice were examined by immunohistochemistry and morphometry from 1 wk to 20 mo of age. Additional mice were treated from 1 to 6 mo with vehicle or mitoquinone (MitoQ), an antioxidant targeted to mitochondria. The leading edge of the SNL lost mitochondria and superoxide production, and became surrounded by a thickened tubular basement membrane. Progression of the SNL as determined by staining with lectin from Lotus tetragonolobus accelerated after 3 mo, but was delayed by treatment with MitoQ (38 ± 4% vs. 28 ± 1%, P < 0.01). Through 9 mo, glomeruli had retained renin staining and intact macula densa, whereas SNL expressed transgelin, an actin-binding protein, but neither kidney injury molecule-1 (KIM-1) nor cell death was observed. After 9 mo, clusters of proximal tubules exhibited localized oxidative stress (4-hydroxynonenal binding), expressed KIM-1, and underwent apoptosis, leading to the formation of atubular glomeruli and accumulation of interstitial collagen. We conclude that nephron integrity is initially maintained in the Ctns(-/-) mouse by adaptive flattening of cells of the SNL through loss of mitochondria, upregulation of transgelin, and thickened basement membrane. This adaptation ultimately fails in adulthood, with proximal tubular disruption, formation of atubular glomeruli, and renal failure. Antioxidant treatment targeted to mitochondria delays initiation of the SNL, and may provide therapeutic benefit in children with cystinosis. PMID:25694483

  3. Tubular optical microcavities of indefinite medium for sensitive liquid refractometers.

    PubMed

    Tang, Shiwei; Fang, Yangfu; Liu, Zhaowei; Zhou, Lei; Mei, Yongfeng

    2016-01-01

    Optical microcavities enable circulated light to intensively interact with a detecting liquid, thus promising high sensitivity in fluidic refractometers. Based on Mie scattering theory, we propose a tubular metamaterial device for liquid sensing, which utilizes anisotropic metamaterials with hyperbolic dispersion called indefinite media (IM). Besides traditional whispering gallery modes (WGMs), such tubular cavities can support surface plasmon polariton (SPP) WGMs, enabling high sensitivity liquid detection. Three configurations of such metamaterial tubes for sensing are discussed: tube-in-liquid, hollow-tube-in-liquid and liquid-in-tube; these are analyzed using numerical formulas and compared with dielectric and metal materials. Compared with traditional dielectric media (DM), the IM tubular cavity exhibits a higher sensitivity (S), which is close to that of a metal tubular cavity. However, compared with metal media, such an IM cavity can achieve higher quality (Q) factors similar to the DM tubular cavity. Therefore, the IM tubular cavity can offer the highest figures of merit (QS) for the sensing performance among the three types of materials. Our results suggest a novel tubular optofluidic device based on metamaterials, which could be useful for liquid refractometers. PMID:26605851

  4. RAB-10 Promotes EHBP-1 Bridging of Filamentous Actin and Tubular Recycling Endosomes.

    PubMed

    Wang, Peixiang; Liu, Hang; Wang, Yu; Liu, Ou; Zhang, Jing; Gleason, Adenrele; Yang, Zhenrong; Wang, Hui; Shi, Anbing; Grant, Barth D

    2016-06-01

    EHBP-1 (Ehbp1) is a conserved regulator of endocytic recycling, acting as an effector of small GTPases including RAB-10 (Rab10). Here we present evidence that EHBP-1 associates with tubular endosomal phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] enriched membranes through an N-terminal C2-like (NT-C2) domain, and define residues within the NT-C2 domain that mediate membrane interaction. Furthermore, our results indicate that the EHBP-1 central calponin homology (CH) domain binds to actin microfilaments in a reaction that is stimulated by RAB-10(GTP). Loss of any aspect of this RAB-10/EHBP-1 system in the C. elegans intestinal epithelium leads to retention of basolateral recycling cargo in endosomes that have lost their normal tubular endosomal network (TEN) organization. We propose a mechanism whereby RAB-10 promotes the ability of endosome-bound EHBP-1 to also bind to the actin cytoskeleton, thereby promoting endosomal tubulation. PMID:27272733

  5. RAB-10 Promotes EHBP-1 Bridging of Filamentous Actin and Tubular Recycling Endosomes

    PubMed Central

    Wang, Yu; Liu, Ou; Zhang, Jing; Gleason, Adenrele; Yang, Zhenrong; Wang, Hui; Shi, Anbing; Grant, Barth D.

    2016-01-01

    EHBP-1 (Ehbp1) is a conserved regulator of endocytic recycling, acting as an effector of small GTPases including RAB-10 (Rab10). Here we present evidence that EHBP-1 associates with tubular endosomal phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] enriched membranes through an N-terminal C2-like (NT-C2) domain, and define residues within the NT-C2 domain that mediate membrane interaction. Furthermore, our results indicate that the EHBP-1 central calponin homology (CH) domain binds to actin microfilaments in a reaction that is stimulated by RAB-10(GTP). Loss of any aspect of this RAB-10/EHBP-1 system in the C. elegans intestinal epithelium leads to retention of basolateral recycling cargo in endosomes that have lost their normal tubular endosomal network (TEN) organization. We propose a mechanism whereby RAB-10 promotes the ability of endosome-bound EHBP-1 to also bind to the actin cytoskeleton, thereby promoting endosomal tubulation. PMID:27272733

  6. [Tubular involvement in glomerular diseases of the kidney (author's transl)].

    PubMed

    Lubee, G; Balzar, E

    1977-01-21

    An attempt is made in this study to provide an answer to the question whether glomerular diseases are accompanied by tubular disorders. The urinary lysozyme activity was determined by means of a turbidimetric assay method in 10 healthy children as controls, 10 patients with glomerulonephritis, 8 patients with Alport's syndrome (hereditary glomerulonephritis with deafness) and 12 children with idiopathic nephrotic syndrome. In most of the cases a significant increase in urinary lysozyme excretion, indicative of tubular damage, was found and this finding correlates well with the tubular morphology of the patients. PMID:320767

  7. Genetics Home Reference: renal tubular acidosis with deafness

    MedlinePlus

    ... a disorder characterized by kidney (renal) problems and hearing loss. The kidneys normally filter fluid and waste products ... In people with renal tubular acidosis with deafness , hearing loss caused by changes in the inner ear (sensorineural ...

  8. Autophagy and Tubular Cell Death in the Kidney.

    PubMed

    Havasi, Andrea; Dong, Zheng

    2016-05-01

    Many common renal insults such as ischemia and toxic injury primarily target the tubular epithelial cells, especially the highly metabolically active proximal tubular segment. Tubular epithelial cells are particularly dependent on autophagy to maintain homeostasis and respond to stressors. The pattern of autophagy in the kidney has a unique spatial and chronologic signature. Recent evidence has shown that there is complex cross-talk between autophagy and various cell death pathways. This review specifically discusses the interplay between autophagy and cell death in the renal tubular epithelia. It is imperative to review this topic because recent discoveries have improved our mechanistic understanding of the autophagic process and have highlighted its broad clinical applications, making autophagy a major target for drug development. PMID:27339383

  9. Atypical presentation of distal renal tubular acidosis in two siblings.

    PubMed

    Tasic, Velibor; Korneti, Petar; Gucev, Zoran; Hoppe, Bernd; Blau, Nenad; Cheong, Hae Il

    2008-07-01

    Primary distal renal tubular acidosis (dRTA) is an inherited disease characterized by the inability of the distal tubule to lower urine pH <5.50 during systemic acidosis. We report two male siblings who presented with severe hyperchloremic metabolic acidosis, high urinary pH, nephrocalcinosis, growth retardation, sensorineural hearing loss, and hypokalemic paralysis. Laboratory investigations revealed proximal tubular dysfunction (low molecular weight proteinuria, generalized hyperaminoaciduria, hypophosphatemia with hyperphosphaturia, and hypouricemia with hyperuricosuria). There was significant hyperoxaluria and laboratory evidence for mild rhabdomyolysis. Under potassium and alkali therapy, proximal tubular abnormalities, muscular enzymes, and oxaluria normalized. A homozygous mutation in the ATP6V1B1 gene, which is responsible for dRTA with early hearing loss, was detected in both siblings. In conclusion, proximal tubular dysfunction and hyperoxaluria may be found in children with dRTA and are reversible under appropriate therapy. PMID:18386070

  10. Distal Renal Tubular Acidosis in Infancy: A Bicarbonate Wasting State

    ERIC Educational Resources Information Center

    Rodriguez-Soriano, J.; And Others

    1975-01-01

    Studied were three unrelated infants with distal renal tubular acidosis (a condition characterized by an inability to acidify the urine to minimal pH levels resulting in the loss of bicarbonates). (DB)

  11. Radially composite piezoelectric ceramic tubular transducer in radial vibration.

    PubMed

    Shuyu, Lin; Shuaijun, Wang

    2011-11-01

    The radially composite piezoelectric tubular transducer is studied. It is composed of radially poled piezoelectric and a long metal tube. The electro-mechanical equivalent circuit of the radially poled piezoelectric and metal tube in radial vibration is obtained. Based on the force and velocity boundary conditions, the six-port electro-mechanical equivalent circuit for the composite tubular transducer is given and the resonance/anti-resonance frequency equations are obtained. The relationship between the resonance frequency and the dimensions is analyzed. Numerically simulated results obtained by the finite element method are compared with those from the analytical method. Composite piezoelectric tubular transducers are designed and manufactured. The resonance/anti-resonance frequencies are measured, and it is shown that the theoretical results are in good agreement with the simulated and experimental results. It is expected that radially composite piezoelectric tubular transducers can be used as high-power ultrasonic radiators in ultrasonic applications, such as ultrasonic liquid processing. PMID:22083782

  12. Development of an alternating flat to tubular Kevlar parachute tape

    SciTech Connect

    Ericksen, R.H.; Koch, R.

    1989-01-01

    An alternating flat to tubular Kevlar tape was developed to replace braided suspension lines and woven tape radials on the new crew escape module parachute system for the F-111 aircraft. Weaves were developed which had high strength efficiency and low weight throughout the flat, tubular, and transition sections. A tubular section strength of 535 lbs at a weight of 0.044 oz/yd was achieved. This reduces suspension line weight by 8% compared with that of the most efficient braid which has a strength of 470 lbs and weighs 0.048 oz/yd. Length measuring procedures for production control and inspection were developed. Using these procedures it was possible to produce alternating weave fabric with less than 1% variation in length in the tubular sections. 3 refs., 4 figs., 3 tabs.

  13. Mobility in geometrically confined membranes.

    PubMed

    Domanov, Yegor A; Aimon, Sophie; Toombes, Gilman E S; Renner, Marianne; Quemeneur, François; Triller, Antoine; Turner, Matthew S; Bassereau, Patricia

    2011-08-01

    Lipid and protein lateral mobility is essential for biological function. Our theoretical understanding of this mobility can be traced to the seminal work of Saffman and Delbrück, who predicted a logarithmic dependence of the protein diffusion coefficient (i) on the inverse of the size of the protein and (ii) on the "membrane size" for membranes of finite size [Saffman P, Delbrück M (1975) Proc Natl Acad Sci USA 72:3111-3113]. Although the experimental proof of the first prediction is a matter of debate, the second has not previously been thought to be experimentally accessible. Here, we construct just such a geometrically confined membrane by forming lipid bilayer nanotubes of controlled radii connected to giant liposomes. We followed the diffusion of individual molecules in the tubular membrane using single particle tracking of quantum dots coupled to lipids or voltage-gated potassium channels KvAP, while changing the membrane tube radius from approximately 250 to 10 nm. We found that both lipid and protein diffusion was slower in tubular membranes with smaller radii. The protein diffusion coefficient decreased as much as 5-fold compared to diffusion on the effectively flat membrane of the giant liposomes. Both lipid and protein diffusion data are consistent with the predictions of a hydrodynamic theory that extends the work of Saffman and Delbrück to cylindrical geometries. This study therefore provides strong experimental support for the ubiquitous Saffman-Delbrück theory and elucidates the role of membrane geometry and size in regulating lateral diffusion. PMID:21768336

  14. Inflatable Tubular Structures Rigidized with Foams

    NASA Technical Reports Server (NTRS)

    Tinker, Michael L.; Schnell, Andrew R.

    2010-01-01

    Inflatable tubular structures that have annular cross sections rigidized with foams, and the means of erecting such structures in the field, are undergoing development. Although the development effort has focused on lightweight structural booms to be transported in compact form and deployed in outer space, the principles of design and fabrication are also potentially applicable to terrestrial structures, including components of ultralightweight aircraft, lightweight storage buildings and shelters, lightweight insulation, and sales displays. The use of foams to deploy and harden inflatable structures was first proposed as early as the 1960s, and has been investigated in recent years by NASA, the U.S. Air Force Research Laboratory, industry, and academia. In cases of deployable booms, most of the investigation in recent years has focused on solid cross sections, because they can be constructed relatively easily. However, solid-section foam-filled booms can be much too heavy for some applications. In contrast, booms with annular cross sections according to the present innovation can be tailored to obtain desired combinations of stiffness and weight through choice of diameters, wall thicknesses, and foam densities. By far the most compelling advantage afforded by this innovation is the possibility of drastically reducing weights while retaining or increasing the stiffnesses, relative to comparable booms that have solid foamfilled cross sections. A typical boom according to this innovation includes inner and outer polyimide film sleeves to contain foam that is injected between them during deployment.

  15. Tubular filamentation for laser material processing.

    PubMed

    Xie, Chen; Jukna, Vytautas; Milián, Carles; Giust, Remo; Ouadghiri-Idrissi, Ismail; Itina, Tatiana; Dudley, John M; Couairon, Arnaud; Courvoisier, Francois

    2015-01-01

    An open challenge in the important field of femtosecond laser material processing is the controlled internal structuring of dielectric materials. Although the availability of high energy high repetition rate femtosecond lasers has led to many advances in this field, writing structures within transparent dielectrics at intensities exceeding 10(13) W/cm(2) has remained difficult as it is associated with significant nonlinear spatial distortion. This letter reports the existence of a new propagation regime for femtosecond pulses at high power that overcomes this challenge, associated with the generation of a hollow uniform and intense light tube that remains propagation invariant even at intensities associated with dense plasma formation. This regime is seeded from higher order nondiffracting Bessel beams, which carry an optical vortex charge. Numerical simulations are quantitatively confirmed by experiments where a novel experimental approach allows direct imaging of the 3D fluence distribution within transparent solids. We also analyze the transitions to other propagation regimes in near and far fields. We demonstrate how the generation of plasma in this tubular geometry can lead to applications in ultrafast laser material processing in terms of single shot index writing, and discuss how it opens important perspectives for material compression and filamentation guiding in atmosphere. PMID:25753215

  16. Developments in open tubular liquid chromatography

    SciTech Connect

    Vargo, J.D.; Maskarinec, M.P.; Sepaniak, M.J.

    1984-04-01

    In this report the band broadening introduced by detection flow cell use in open tubular liquid chromatography (OTLC) was thoroughly examined. Serious loss of chromatographic efficiency and resolution can occur if the flow cell size is not properly matched with the ID of the column. Detection in a flow cell was shown to be more sensitive than on-column detection, but at the expense of some loss in chromatographic efficiency. The use of fluorescence as a sensitive detection method for OTLC was presented in detail. The application of the laser as excitation source was developed. The laser based fluorometric system proved to be a sensitive detection method which was relatively easy to operate and optimize. This system allowed on-column detection to be used. An electro-etching procedure for borosilicate glass developed by Jorgenson and Guthrie was modified such that longer columns could be effectively etched. It was shown that the acidification of the etched glass surface significantly increased capacity factor (k') values for bonded phase columns. Soda-lime glass was shown to be the most suitable material for column fabrication. Complex natural samples were separated by OTLC. The alkyl phenol compounds in a coal-derived liquid were separated and tentatively identified. A chromatographic separation of a derivatized sample of coal oil bases is also presented.

  17. Cytocompatibility of a silk fibroin tubular scaffold.

    PubMed

    Wang, Jiannan; Wei, Yali; Yi, Honggen; Liu, Zhiwu; Sun, Dan; Zhao, Huanrong

    2014-01-01

    Regenerated silk fibroin (SF) materials are increasingly used for tissue engineering applications. In order to explore the feasibility of a novel biomimetic silk fibroin tubular scaffold (SFTS) crosslinked by poly(ethylene glycol) diglycidyl ether (PEG-DE), biocompatibility with cells was evaluated. The novel biomimetic design of the SFTS consisted of three distinct layers: a regenerated SF intima, a silk braided media and a regenerated SF adventitia. The SFTS exhibited even silk fibroin penetration throughout the braid, forming a porous layered tube with superior mechanical, permeable and cell adhesion properties that are beneficial to vascular regeneration. Cytotoxicity and cell compatibility were tested on L929 cells and human umbilical vein endothelial cells (EA.hy926). DNA content analysis, scanning electron and confocal microscopies and MTT assay showed no inhibitory effects on DNA replication. Cell morphology, viability and proliferation were good for L929 cells, and satisfactory for EA.hy926 cells. Furthermore, the suture retention strength of the SFTS was about 23N and the Young's modulus was 0.2-0.3MPa. Collectively, these data demonstrate that PEG-DE crosslinked SFTS possesses the appropriate cytocompatibility and mechanical properties for use as vascular scaffolds as an alternative to vascular autografts. PMID:24268279

  18. Tubular filamentation for laser material processing

    PubMed Central

    Xie, Chen; Jukna, Vytautas; Milián, Carles; Giust, Remo; Ouadghiri-Idrissi, Ismail; Itina, Tatiana; Dudley, John M.; Couairon, Arnaud; Courvoisier, Francois

    2015-01-01

    An open challenge in the important field of femtosecond laser material processing is the controlled internal structuring of dielectric materials. Although the availability of high energy high repetition rate femtosecond lasers has led to many advances in this field, writing structures within transparent dielectrics at intensities exceeding 1013 W/cm2 has remained difficult as it is associated with significant nonlinear spatial distortion. This letter reports the existence of a new propagation regime for femtosecond pulses at high power that overcomes this challenge, associated with the generation of a hollow uniform and intense light tube that remains propagation invariant even at intensities associated with dense plasma formation. This regime is seeded from higher order nondiffracting Bessel beams, which carry an optical vortex charge. Numerical simulations are quantitatively confirmed by experiments where a novel experimental approach allows direct imaging of the 3D fluence distribution within transparent solids. We also analyze the transitions to other propagation regimes in near and far fields. We demonstrate how the generation of plasma in this tubular geometry can lead to applications in ultrafast laser material processing in terms of single shot index writing, and discuss how it opens important perspectives for material compression and filamentation guiding in atmosphere. PMID:25753215

  19. Cadmium, metallothionein and renal tubular toxicity.

    PubMed

    Nordberg, M; Jin, T; Nordberg, G F

    1992-01-01

    Cadmium-induced nephrotoxicity develops at cadmium concentrations in the renal cortex of 10-300 micrograms/g wet weight. The actual concentration at which it develops depends on a number of factors, e.g., exposure route, chemical species of cadmium administered, rate of administration and simultaneous exposure to other metals. The role of these factors can be explained by a mechanism of cadmium nephrotoxicity in which both extracellular and intracellular metallothionein binding play an essential role. In reindeer used for human food, cadmium was shown to be bound to metallothionein-like proteins. If cadmium bound to such proteins enters the blood plasma via the gastrointestinal tract, this is of special toxicological significance. Metallothionein-bound cadmium in the plasma of experimental animals is efficiently transported to the kidney. Tubular dysfunction in the kidney following a normally tubulotoxic dose of cadmium bound to metallothionein was prevented by preinduction of metallothionein synthesis by small non-toxic doses of cadmium. PMID:1303954

  20. Electrolyte composition of renal tubular cells in gentamicin nephrotoxicity

    SciTech Connect

    Matsuda, O.; Beck, F.X.; Doerge, A.T.; Thurau, K.

    1988-06-01

    The effect of long-term gentamicin administration on sodium, potassium, chloride and phosphorus concentrations was studied in individual rat renal tubular cells using electron microprobe analysis. Histological damage was apparent only in proximal tubular cells. The extent of damage was only mild after 7 days of gentamicin administration (60 mg/kg body wt/day) but much more pronounced after 10 days. GFR showed a progressive decline during gentamicin treatment. In non-necrotic proximal tubular cells, sodium was increased from 14.6 +/- 0.3 (mean +/- SEM) in controls to 20.6 +/- 0.4 after 7 and 22.0 +/- 0.8 mmol/kg wet wt after 10 days of gentamicin administration. Chloride concentration was higher only after 10 days (20.6 +/- 0.6 vs. 17.3 +/- 0.2 mmol/kg wet wt). Both cell potassium and phosphorus concentrations were diminished by 6 and 15, and by 8 and 25 mmol/kg wet wt after 7 and 10 days of treatment, respectively. In contrast, no major alterations in distal tubular cell electrolyte concentrations could be observed after either 7 or 10 days of gentamicin administration. As in proximal tubular cells, distal tubular cell phosphorus concentrations were, however, lowered by gentamicin treatment. These results clearly indicate that gentamicin exerts its main effect on proximal tubular cells. Decreased potassium and increased sodium and chloride concentrations were observed in proximal tubular cells exhibiting only mild histological damage prior to the onset of advanced tissue injury. Necrotic cells, on the other hand, showed widely variable intracellular electrolyte concentration patterns.

  1. Effects of cytokines on potassium channels in renal tubular epithelia.

    PubMed

    Nakamura, Kazuyoshi; Komagiri, You; Kubokawa, Manabu

    2012-02-01

    Renal tubular potassium (K(+)) channels play important roles in the formation of cell-negative potential, K(+) recycling, K(+) secretion, and cell volume regulation. In addition to these physiological roles, it was reported that changes in the activity of renal tubular K(+) channels were involved in exacerbation of renal cell injury during ischemia and endotoxemia. Because ischemia and endotoxemia stimulate production of cytokines in immune cells and renal tubular cells, it is possible that cytokines would affect K(+) channel activity. Although the regulatory mechanisms of renal tubular K(+) channels have extensively been studied, little information is available about the effects of cytokines on these K(+) channels. The first report was that tumor necrosis factor acutely stimulated the single channel activity of the 70 pS K(+) channel in the rat thick ascending limb through activation of tyrosine phosphatase. Recently, it was also reported that interferon-γ (IFN-γ) and interleukin-1β (IL-1β) modulated the activity of the 40 pS K(+) channel in cultured human proximal tubule cells. IFN-γ exhibited a delayed suppression and an acute stimulation of K(+) channel activity, whereas IL-1β acutely suppressed the channel activity. Furthermore, these cytokines suppressed gene expression of the renal outer medullary potassium channel. The renal tubular K(+) channels are functionally coupled to the coexisting transporters. Therefore, the effects of cytokines on renal tubular transporter activity should also be taken into account, when interpreting their effects on K(+) channel activity. PMID:22042037

  2. Straightening tubular flow for side-by-side visualization.

    PubMed

    Angelelli, Paolo; Hauser, Helwig

    2011-12-01

    Flows through tubular structures are common in many fields, including blood flow in medicine and tubular fluid flows in engineering. The analysis of such flows is often done with a strong reference to the main flow direction along the tubular boundary. In this paper we present an approach for straightening the visualization of tubular flow. By aligning the main reference direction of the flow, i.e., the center line of the bounding tubular structure, with one axis of the screen, we are able to natively juxtapose (1.) different visualizations of the same flow, either utilizing different flow visualization techniques, or by varying parameters of a chosen approach such as the choice of seeding locations for integration-based flow visualization, (2.) the different time steps of a time-dependent flow, (3.) different projections around the center line , and (4.) quantitative flow visualizations in immediate spatial relation to the more qualitative classical flow visualization. We describe how to utilize this approach for an informative interactive visual analysis. We demonstrate the potential of our approach by visualizing two datasets from two different fields: an arterial blood flow measurement and a tubular gas flow simulation from the automotive industry. PMID:22034324

  3. Structural studies of tubular discotic liquid crystals

    NASA Astrophysics Data System (ADS)

    Mindyuk, Oksana Yaroslavovna

    1999-11-01

    Discotic liquid crystals based on the rigid ring-shaped phenylacetylene macrocycle molecule (PAM) are of great interest due to their potential organization into supramolecular channels. We have used high resolution X-ray diffraction to study the structure of pure and doped PAM and to demonstrate that PAM forms a tubular columnar liquid crystal with an unexpected distortion and doubling of the underlying hexagonal lattice. We have doped PAM with different percentages of silver ions and determined that doping did not change peak positions on the powder diffraction data but significantly altered the intensity of the peaks. This implies that the silver ions were most likely intercalated within the channels formed by the PAM molecules, thus leaving the lattice parameters unaffected. We have also used grazing incidence X-ray diffraction and X-ray reflectivity to study Langmuir films of PAM. PAM adopts an "edge-on" molecular arrangement at the air-water interface. We will discuss the direct observation of the structural reorganization within macromolecular Langmuir films of disc-shaped ionophoric molecules arising from interactions with potassium and cesium ions in the subphase. The columnar order is disrupted by CsCl in the subphase and strongly enhanced by KCl in the subphase, thus effectively tailoring the structural properties of the Langmuir films for potential applications. We have also used X-ray reflectivity (XR) and grazing incidence x-ray diffraction (GID) to study Langmuir films of another macrocyclic ionophore: torand (tributyldodecahydrohexaazakekulene, "TBDK") molecules. TBDK is a rigid, triangular molecule; it has been investigated as a potential surface-active complexing agent. The system forms a stable monolayer at the air-water interface and exhibits two distinct structural phases at lower and higher pressures.

  4. Clinical profile of distal renal tubular acidosis.

    PubMed

    Jha, Ratan; Muthukrishnan, J; Shiradhonkar, Shekhar; Patro, Kiran; Harikumar, Kvs; Modi, K D

    2011-03-01

    To determine the clinical profile and progression of renal dysfunction in distal renal tubular acidosis (dRTA), we retrospectively studied 96 consecutive cases of dRTA diagnosed at our center. Patients with unexplained metabolic bone disease, short stature, hypokalemia, re-current renal stones, chronic obstructive uropathy or any primary autoimmune condition known to cause dRTA were screened. Distal RTA was diagnosed on the basis of systemic metabolic acidosis with urine pH >5.5 and positive urine anion gap. In those patients who had fasting urine pH >5.5 with normal baseline systemic pH and bicarbonate levels (incomplete RTA), acid load test with ammonium chloride was done. A cause of dRTA could be established in 53 (54%) patients. Urological defect in children (22/44) and autoimmune disease in adults (11/52) were the commonest causes. Hypokalemic paralysis, proximal muscle weakness and voiding difficulty were the common modes of presentation. Doubling of serum creatinine during the study period was noted in 13 out of 27 patients who had GFR <60 mL/min at presentation whereas in only one of the 70 with initial GFR >60 mL/min (P <0.005). In conclusion, urological disorders were the commonest cause of dRTA in children while autoimmune disorders were the commonest asso-ciation in adults. Worse baseline renal function, longer duration of disease and greater frequency of nephrolithiasis/nephrocalcinosis and urological disorders were noted in those who had wor-sening of renal dysfunction during the study period. PMID:21422623

  5. Human embryonic mesenchymal stem cells participate in differentiation of renal tubular cells in newborn mice

    PubMed Central

    Yuan, Li; Liu, Hou-Qi; Wu, Min-Juan

    2016-01-01

    Stem cells are used with increasing success in the treatment of renal tubular injury. However, whether mesenchymal stem cells (MSC) differentiate into renal tubular epithelial cells remains controversial. The aims of the present study were to observe the localization of human embryonic MSCs (hMSCs) in the kidneys of newborn mice, and to investigate hMSC differentiation into tubular epithelium. Primary culture hMSCs were derived from 4–7-week-old embryos and labeled with the cell membrane fluorescent dye PKH-26. The degree of apoptosis, cell growth, differentiation and localization of hMSCs with and without this label were then determined using immunohistochemical methods and flow cytometry. hMSCs and PKH26-labeled hMSCs were revealed to differentiate into chondrocytes and adipocytes, and were demonstrated to have similar proliferative capability. In the two cell types, the antigens CD34 and CD45, indicative of hematopoietic lineages, were not expressed; however, the expression of the mesenchymal markers CD29 and CD90 in MSCs, was significantly increased. During a 4-week culture period, laser confocal microscopy revealed that PKH26-labeled hMSCs in the kidneys of newborn mice gradually dispersed. Two weeks after the injection of the PKH26-labeled cells, the percentage of PKH26-labeled hMSCs localized to the renal tubules was 10±2.1%. In conclusion, PKH26 labeling has no effect on hMSC differentiation, proliferation and mesenchymal cell surface features, and hMSCs injected into the kidneys of newborn mice may transform to renal tubule epithelium. PMID:27446255

  6. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, the possibility of using a more complex interfacial engineering approach to the development of reliable and stable oxygen transport perovskite ceramic membranes/metal seals is discussed. Experiments are presented and ceramic/metal interactions are characterized. Crack growth and fracture toughness of the membrane in the reducing conditions are also discussed. Future work regarding this approach is proposed are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  7. Prevention of apoptosis averts glomerular tubular disconnection and podocyte loss in proteinuric kidney disease.

    PubMed

    Burlaka, Ievgeniia; Nilsson, Linnéa M; Scott, Lena; Holtbäck, Ulla; Eklöf, Ann-Christine; Fogo, Agnes B; Brismar, Hjalmar; Aperia, Anita

    2016-07-01

    There is a great need for treatment that arrests progression of chronic kidney disease. Increased albumin in urine leads to apoptosis and fibrosis of podocytes and tubular cells and is a major cause of functional deterioration. There have been many attempts to target fibrosis, but because of the lack of appropriate agents, few have targeted apoptosis. Our group has described an ouabain-activated Na,K-ATPase/IP3R signalosome, which protects from apoptosis. Here we show that albumin uptake in primary rat renal epithelial cells is accompanied by a time- and dose-dependent mitochondrial accumulation of the apoptotic factor Bax, down-regulation of the antiapoptotic factor Bcl-xL and mitochondrial membrane depolarization. Ouabain opposes these effects and protects from apoptosis in albumin-exposed proximal tubule cells and podocytes. The efficacy of ouabain as an antiapoptotic and kidney-protective therapeutic tool was then tested in rats with passive Heymann nephritis, a model of proteinuric chronic kidney disease. Chronic ouabain treatment preserved renal function, protected from renal cortical apoptosis, up-regulated Bax, down-regulated Bcl-xL, and rescued from glomerular tubular disconnection and podocyte loss. Thus we have identified a novel clinically feasible therapeutic tool, which has the potential to protect from apoptosis and rescue from loss of functional tissue in chronic proteinuric kidney disease. PMID:27217195

  8. Renal proximal tubular dysgenesis associated with severe neonatal hemosiderotic liver disease.

    PubMed

    Bale, P M; Kan, A E; Dorney, S F

    1994-01-01

    We report the necropsy findings for three infants with the unusual combination of proximal renal tubular dysgenesis and severe congenital liver disease with excessive iron in several organs resembling neonatal hemochromatosis. Two of the infants were caucasian siblings and one was an Australian aborigine. One died in utero at 35 weeks of gestation and two died at 7 days. The liveborn infants presented with anuria and liver failure. The livers all showed marked loss of hepatocytes and replacement by pseudotubules in the collapsed lobules. The liveborn infants also showed giant cell transformation of hepatocytes, small regenerative nodules, cholestasis, and normal bile ducts. Absence of proximal renal convolutions was confirmed by epithelial membrane antigen positivity in nearly all tubules. In each family there was another sibling with congenital liver disease, fatal in one case, but no renal tubular dysgenesis. No infection or metabolic disease was uncovered in any of our patients, and the cause of the hepatocyte destruction was not determined. The combination in three infants of two rare congenital diseases could be genetic or acquired in utero from the same etiological agent. Alternatively, the absence of proximal convolutions could be secondary to hypoperfusion, perhaps because of shock due to extensive necrosis of hepatocytes. PMID:8066004

  9. Anorexia nervosa, laxative abuse, hypopotassemia and distal renal tubular acidosis.

    PubMed

    Pines, A; Kaplinsky, N; Olchovsky, D; Frankl, O; Goldfarb, D; Iaina, A

    1985-01-01

    A case of anorexia nervosa in a 28-year-old woman with laxative abuse, hypopotassemia and severe metabolic acidosis, is described. The diagnosis of classical renal tubular acidosis, Type I, was confirmed by our inability to decrease urinary pH beyond 5.5 and to increase ammonia excretion during an ammonium chloride loading test. A bicarbonate loading test and normal plasma aldosterone with high renin activity excluded proximal renal tubular acidosis, hyporeninemic-hypoaldosteronemic renal tubular acidosis and Bartter's syndrome. The inability to increase ammonium excretion during severe metabolic acidosis following ammonium chloride loading did not favor the possibility of a transient physiological adaptation of ammoniagenesis at the tubular cell level, related to potassium depletion. Although mental disorder, laxative abuse, abstinence from food intake and severe potassium depletion intermingled in a vicious cycle, we assume that one of the following possibilities may explain the clinical presentation in our patient: either two separated and unrelated disorders, or laxative abuse as the cause of renal tubular acidification impairment. PMID:3972559

  10. Autophagy Induces Prosenescent Changes in Proximal Tubular S3 Segments.

    PubMed

    Baisantry, Arpita; Bhayana, Sagar; Rong, Song; Ermeling, Esther; Wrede, Christoph; Hegermann, Jan; Pennekamp, Petra; Sörensen-Zender, Inga; Haller, Hermann; Melk, Anette; Schmitt, Roland

    2016-06-01

    Evidence suggests that autophagy promotes the development of cellular senescence. Because cellular senescence contributes to renal aging and promotes the progression from AKI to CKD, we investigated the potential effect of tubular autophagy on senescence induction. Compared with kidneys from control mice, kidneys from mice with conditional deletion of autophagy-related 5 (Atg5) for selective ablation of autophagy in proximal tubular S3 segments (Atg5(Δ) (flox/) (Δ) (flox)) presented with significantly less tubular senescence, reduced interstitial fibrosis, and superior renal function 30 days after ischemia/reperfusion injury. To correlate this long-term outcome with differences in the early injury process, kidneys were analyzed 2 hours and 3 days after reperfusion. Notably, compared with kidneys of control mice, Atg5(Δ) (flox/) (Δ) (flox) kidneys showed more cell death in outer medullary S3 segments at 2 hours but less tubular damage and inflammation at day 3. These data suggest that the lack of autophagy prevents early survival mechanisms in severely damaged tubular cells. However, if such compromised cells persist, then they may lead to maladaptive repair and proinflammatory changes, thereby facilitating the development of a senescent phenotype and CKD. PMID:26487561

  11. Construction and evaluation of PVC conventional and tubular tripelennamine-selective electrodes: their application in pharmaceutical preparations.

    PubMed

    Lima, J L; Montenegro, M C; Sales, M G

    1996-06-01

    The construction and evaluation of tripelennamine conventionally-shaped ion-selective electrodes and tubular detectors for the determination of this compound in pharmaceutical formulations are described. Electrodes with conventional configuration have been constructed without an internal reference solution, using several types of immobilized ionic sensors in PVC. The different electrode membranes were prepared by using tripelennamine tetraphenylborate as ionic-exchanger, dissolved in 2-nitrophenyl octyl ether (type A), dibutylphthalate (type B) and bis-(2-ethylhexyl)sebacate (type C) as plasticizer solvents. The general working characteristics of the different types of conventional electrodes were evaluated in tripelennamine solutions, with adjusted ionic strength, showing a linear response in the concentration range of about 4 x 10(-5) - 1 x 10(-1) M and a slope near the theoretical value. The electrodes presented a fast response (> 20 s) and a high reproducibility (> or = 0.2 mV per day). The electrode selectivity in the presence of some interferents, such as sodium, potassium, lithium, ammonium, chlorpheniramine, diphenydramine, promethazine, meclizine and pentazocine, was good, particularly for those whose sensor membrane was prepared with tripelennamine tetraphenylborate dissolved in 2-nitrophenyl octyl ether (type A). Tubular detectors were also prepared using the same sensor membrane and were evaluated in a low-dispersion flow-injection manifold. Under these conditions the detectors presented response characteristics similar to those of the corresponding conventionally-shaped electrodes. The analysis of different pharmaceutical forms (creams, syrups and gels) gave good results with mean recoveries of 99.8-100.6% when the experiments were conducted by direct potentiometry and 99.9-100.4% where the same determinations were conducted by flow-injection analysis with tubular detectors. PMID:8817997

  12. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    SciTech Connect

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; Liu, Rui; Chen, Shuang; Chen, Si; Yung, Ka Yi; Yamato, Kazuhiro; Cai, Zhonghou; Bright, Frank V.; Zeng, Xiao Cheng; Gong, Bing

    2015-01-01

    As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of Kdimer > 1013 M-1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (-49.77 kcal mol-1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results in well-aligned tubular stacks. The persistent tubular assemblies of 3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for 3.

  13. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    SciTech Connect

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; Liu, Rui; Chen, Shuang; Chen, Si; Yung, Ka Yi; Yamato, Kazuhiro; Cai, Zhonghou; Bright, Frank V.; Zeng, Xiao Cheng; Gong, Bing

    2014-09-16

    As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of K-dimer > 1013 M-1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (-49.77 kcal mol-1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results in well-aligned tubular stacks. Furthermore, the persistent tubular assemblies of 3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for 3.

  14. Open–closed switching of synthetic tubular pores

    PubMed Central

    Kim, Yongju; Kang, Jiheong; Shen, Bowen; Wang, Yanqiu; He, Ying; Lee, Myongsoo

    2015-01-01

    While encouraging progress has been made on switchable nanopores to mimic biological channels and pores, it remains a great challenge to realize long tubular pores with a dynamic open–closed motion. Here we report μm-long, dynamic tubular pores that undergo rapid switching between open and closed states in response to a thermal signal in water. The tubular walls consist of laterally associated primary fibrils stacked from disc-shaped molecules in which the discs readily tilt by means of thermally regulated dehydration of the oligoether chains placed on the wall surfaces. Notably, this pore switching mediates a controlled water-pumping catalytic action for the dehydrative cyclization of adenosine monophosphate to produce metabolically active cyclic adenosine monophosphate. We believe that our work may allow the creation of a variety of dynamic pore structures with complex functions arising from open–closed motion. PMID:26456695

  15. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    DOE PAGESBeta

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; Liu, Rui; Chen, Shuang; Chen, Si; Yung, Ka Yi; Yamato, Kazuhiro; Cai, Zhonghou; Bright, Frank V.; et al

    2014-09-16

    As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of K-dimer > 1013 M-1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (-49.77 kcal mol-1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results in well-aligned tubular stacks. Furthermore, themore » persistent tubular assemblies of 3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for 3.« less

  16. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    DOE PAGESBeta

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; Liu, Rui; Chen, Shuang; Chen, Si; Yung, Ka Yi; Yamato, Kazuhiro; Cai, Zhonghou; Bright, Frank V.; et al

    2015-01-01

    As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of Kdimer > 1013 M-1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (-49.77 kcal mol-1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results in well-aligned tubular stacks. The persistentmore » tubular assemblies of 3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for 3.« less

  17. Power generation characteristics of tubular type SOFC by wet process

    SciTech Connect

    Tajiri, H.; Nakayama, T.; Kuroishi, M.

    1996-12-31

    The development of a practical solid oxide fuel cell requires improvement of a cell performance and a cell manufacturing technology suitable for the mass production. In particular tubular type SOFC is thought to be superior in its reliability because its configuration can avoid the high temperature sealing and reduce the thermal stress resulting from the contact between cells. The authors have fabricated a tubular cell with an air electrode support by a wet processing technique, which is suitable for mass production in improving a power density. To enhance the power output of the module, the Integrated Tubular-Type (ITT) cell has been developed. This paper reports the performance of the single cells with various active anode areas and the bundle with series-connected 9-ITT cells with an active anode area of 840 cm{sup 2}.

  18. Klinefelter's syndrome with renal tubular acidosis: impact on height.

    PubMed

    Jebasingh, F; Paul, T V; Spurgeon, R; Abraham, S; Jacob, J J

    2010-02-01

    A 19-year-old Indian man presented with a history of proximal muscle weakness, knock knees and gynaecomastia. On examination he had features of rickets and bilateral small testes. Karyotyping revealed a chromosomal pattern of 47,XXX, confirming the diagnosis of Klinefelter's syndrome. He was also found to have hyperchloraemic metabolic acidosis with hypokalaemia, hypophosphataemia, phosphaturia and glycosuria, which favoured a diagnosis of proximal renal tubular acidosis. Patients with Klinefelter's syndrome typically have a tall stature due to androgen deficiency, resulting in unfused epiphyses and an additional X chromosome. However, this patient had a short stature due to associated proximal renal tubular acidosis. To the best of our knowledge, this is the second case of Klinefelter's syndrome with short stature due to associated renal tubular acidosis reported in the literature. This report highlights the need to consider other causes when patients with Klinefelter's syndrome present with a short stature. PMID:20358137

  19. Pulse shear stress for anaerobic membrane bioreactor fouling control.

    PubMed

    Yang, Jixiang; Spanjers, Henri; van Lier, Jules B

    2011-01-01

    Increase of shear stress at membrane surfaces is a generally applied strategy to minimize membrane fouling. It has been reported that a two-phase flow, better known as slug flow, is an effective way to increase shear stress. Hence, slug flow was introduced into an anaerobic membrane bioreactor for membrane fouling control. Anaerobic suspended sludge was cultured in an anaerobic membrane bioreactor (AMBR) operated with a side stream inside-out tubular membrane unit applying sustainable flux flow regimes. The averaged particle diameter decreased from 20 to 5 microm during operation of the AMBR. However, the COD removal efficiency did not show any significant deterioration, whereas the specific methanogenic activity (SMA) increased from 0.16 to 0.41 gCOD/g VSS/day. Nevertheless, the imposed gas slug appeared to be insufficient for adequate fouling control, resulting in rapidly increasing trans membrane pressures (TMP) operating at a flux exceeding 16 L/m2/h. Addition of powdered activated carbon (PAC) enhanced the effect of slug flow on membrane fouling. However, the combined effect was still considered as not being significant. The tubular membrane was subsequently equipped with inert inserts for creating a locally increased shear stress for enhanced fouling control. Results show an increase in the membrane flux from 16 L/m2/h to 34 L/m2/h after the inserts were mounted in the membrane tube. PMID:22097007

  20. How to make tubular crystals by reconstitution of detergent-solubilized Ca2(+)-ATPase.

    PubMed Central

    Young, H S; Rigaud, J L; Lacapère, J J; Reddy, L G; Stokes, D L

    1997-01-01

    In an attempt to better define the parameters governing reconstitution and two-dimensional crystallization of membrane proteins, we have studied Ca2(+)-ATPase from rabbit sarcoplasmic reticulum. This ion pump forms vanadate-induced crystals in its native membrane and has previously been reconstituted at high lipid-to-protein ratios for functional studies. We have characterized the reconstitution of purified Ca2(+)-ATPase at low lipid-to-protein ratios and discovered procedures that produce long, tubular crystals suitable for helical reconstruction. C12E8 (n-dodecyl-octaethylene-glycol monoether) was used to fully solubilize various mixtures of lipid and purified Ca2(+)-ATPase, and BioBeads were then used to remove the C12E8. Slow removal resulted in two populations of vesicles, and the proteoliposome population was separated from the liposome population on a sucrose density gradient. These proteoliposomes had a lipid-to-protein ratio of 1:2, and virtually 100% of molecules faced the outside of vesicles, as determined by fluorescein isothiocyanate labeling. Cycles of freeze-thaw caused considerable aggregation of these proteoliposomes, and, if phosphatidyl ethanolamine and phosphatidic acid were included, or if the bilayers were doped with small amounts of C12E8, vanadate-induced tubular crystals grew from the aggregates. Thus our procedure comprised two steps-reconstitution followed by crystallization-allowing us to consider mechanisms of bilayer formation separately from those of crystallization and tube formation. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 5 FIGURE 6 PMID:9168030

  1. Electrocatalytic oxidation of n-propanol to produce propionic acid using an electrocatalytic membrane reactor.

    PubMed

    Li, Jiao; Li, Jianxin; Wang, Hong; Cheng, Bowen; He, Benqiao; Yan, Feng; Yang, Yang; Guo, Wenshan; Ngo, Huu Hao

    2013-05-18

    An electrocatalytic membrane reactor assembled using a nano-MnO2 loading microporous Ti membrane as an anode and a tubular stainless steel as a cathode was used to oxidize n-propanol to produce propionic acid. The high efficiency and selectivity obtained is related to the synergistic effect between the reaction and separation in the reactor. PMID:23572114

  2. Hot fire test results of subscale tubular combustion chambers

    NASA Technical Reports Server (NTRS)

    Kazaroff, John M.; Jankovsky, Robert S.; Pavli, Albert J.

    1992-01-01

    Advanced, subscale, tubular combustion chambers were built and test fired with hydrogen-oxygen propellants to assess the increase in fatigue life that can be obtained with this type of construction. Two chambers were tested: one ran for 637 cycles without failing, compared to a predicted life of 200 cycles for a comparable smooth-wall milled-channel liner configuration. The other chamber failed at 256 cycles, compared to a predicted life of 118 cycles for a comparable smooth-wall milled-channel liner configuration. Posttest metallographic analysis determined that the strain-relieving design (structural compliance) of the tubular configuration was the cause of this increase in life.

  3. Lipid Gymnastics: Tethers and Fingers in membrane

    NASA Astrophysics Data System (ADS)

    Tayebi, Lobat; Miller, Gregory; Parikh, Atul

    2009-03-01

    A significant body of evidence now links local mesoscopic structure (e.g., shape and composition) of the cell membrane with its function; the mechanisms by which cellular membranes adopt the specific shapes remain poorly understood. Among all the different structures adopted by cellular membranes, the tubular shape is one of the most surprising one. While their formation is typically attributed to the reorganization of membrane cytoskeleton, many exceptions exist. We report the instantaneous formation of tubular membrane mesophases following the hydration under specific thermal conditions. The shapes emerge in a bimodal way where we have two distinct diameter ranges for tubes, ˜20μm and ˜1μm, namely fat fingers and narrow tethers. We study the roughening of hydrated drops of 3 lipids in 3 different spontaneous curvatures at various temp. and ionic strength to figure out the dominant effect in selection of tethers and fingers. Dynamics of the tubes are of particular interest where we observe four distinct steps of birth, coiling, uncoiling and retraction with different lifetime on different thermal condition. These dynamics appear to reflect interplay between membrane elasticity, surface adhesion, and thermal or hydrodynamic gradient.

  4. In vitro hydrodynamic evaluation of a biovalve with stent (tubular leaflet type) for transcatheter pulmonary valve implantation.

    PubMed

    Sumikura, Hirohito; Nakayama, Yasuhide; Ohnuma, Kentaro; Kishimoto, Satoru; Takewa, Yoshiaki; Tatsumi, Eisuke

    2015-12-01

    We have been developing an autologous heart valve-shaped tissue with a stent (stent-biovalve) for transcatheter pulmonary valve implantation (TPVI) using "in-body tissue architecture" technology. In this study, the hydrodynamic performance of a stent-biovalve with tubular leaflets was evaluated by changing its leaflet height in an in vitro test in order to determine the appropriate stent-biovalve form for the pulmonary valve. A specially designed, self-expandable, stent-mounted, cylindrical acrylic mold was placed in a dorsal subcutaneous pouch of goat, and the implant was extracted 2 months later. Only the cylindrical acrylic mold was removed from the implant, and a tubular hollow structure of membranous connective tissue impregnated with the stent strut was obtained. Half of tubular tissue was completely folded in half inwards, and 3 commissure parts were connected to form 3 leaflets, resulting in the preparation of a stent-biovalve with tubular leaflets (25-mm ID). The stent-biovalve with adjusting leaflet height (13, 14, 15, 17, 20, and 25 mm) was fixed to a specially designed pulsatile mock circulation circuit under pulmonary valve conditions using 37 °C saline. The mean pressure difference and effective orifice area were better than those of the biological valve. The lowest and highest leaflet heights had a high regurgitation rate due to lack of coaptation or prevention of leaflet movement, respectively. The lowest regurgitation (ca. 11%) was observed at a height of 15 mm. The leaflet height was found to significantly affect the hydrodynamics of stent-biovalves, and the existence of an appropriate leaflet height became clear. PMID:26141924

  5. Water desalination by air-gap membrane distillation using meltblown polypropylene nanofiber membrane

    NASA Astrophysics Data System (ADS)

    Rosalam, S.; Chiam, C. K.; Widyaparamitha, S.; Chang, Y. W.; Lee, C. A.

    2016-06-01

    This paper presents a study of air gap membrane distillation (AGMD) using meltblown polypropylene (PP) nanofiber membrane to produce fresh water via desalination process. PP nanofiber membranes with the effective area 0.17 m2 are tested with NaCl solutions (0.5 - 4.0 wt.%) and seawater as the feed solutions (9400 - 64800 μS/cm) in a tubular membrane module. Results show that the flux decreases with increasing the membrane thickness from 547 to 784 μm. The flux increases with the feed flow rate and temperature difference across the membrane. The feed concentration affects the flux insignificantly. The AGMD system can reject the salts at least 96%. Water vapor permeation rate is relatively higher than solute permeation rate resulting in the conductivity value of permeate decreases when the corresponding flux increases. The AGMD system produces the fresh water (200 - 1520 μS/cm) that is suitable for drinking, fisheries or irrigation.

  6. Nonperturbative Renormalization Group Approach to Polymerized Membranes

    NASA Astrophysics Data System (ADS)

    Essafi, Karim; Kownacki, Jean-Philippe; Mouhanna, Dominique

    2014-03-01

    Membranes or membrane-like materials play an important role in many fields ranging from biology to physics. These systems form a very rich domain in statistical physics. The interplay between geometry and thermal fluctuations lead to exciting phases such flat, tubular and disordered flat phases. Roughly speaking, membranes can be divided into two group: fluid membranes in which the molecules are free to diffuse and thus no shear modulus. On the other hand, in polymerized membranes the connectivity is fixed which leads to elastic forces. This difference between fluid and polymerized membranes leads to a difference in their critical behaviour. For instance, fluid membranes are always crumpled, whereas polymerized membranes exhibit a phase transition between a crumpled phase and a flat phase. In this talk, I will focus only on polymerized phantom, i.e. non-self-avoiding, membranes. The critical behaviour of both isotropic and anisotropic polymerized membranes are studied using a nonperturbative renormalization group approach (NPRG). This allows for the investigation of the phase transitions and the low temperature flat phase in any internal dimension D and embedding d. Interestingly, graphene behaves just as a polymerized membrane in its flat phase.

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

    PubMed

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

    2016-04-19

    Electrically conductive, graphene-coated, hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 and 0.9 V) using a new rectangular reactor configuration compared to a previous tubular design (0.7 V). The onset of biofouling was delayed and minimized in rectangular reactors operated at 0.9 V compared to those at 0.7 V due to higher rates of hydrogen production. Maximum transmembrane pressures for the rectangular reactor were only 0.10 bar (0.7 V) or 0.05 bar (0.9 V) after 56 days of operation compared to 0.46 bar (0.7 V) for the tubular reactor after 52 days. The thickness of the membrane biofouling layer was approximately 0.4 μm for rectangular reactors and 4 μm for the tubular reactor. Higher permeate quality (TSS = 0.05 mg/L) was achieved in the rectangular AnEMBR than that in the tubular AnEMBR (TSS = 17 mg/L), likely due to higher current densities that minimized the accumulation of cells in suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance. PMID:26691927

  8. 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.

  9. Coiled sheet metal strip opens into tubular configuration

    NASA Technical Reports Server (NTRS)

    Park, J. J.

    1966-01-01

    Copper alloy is converted into a spring material that can be rolled into a compact coil which will spontaneously open to form a tube in the long direction of the strip. The copper alloy is passed through a furnace at a prescribed temperature while restraining the strip in the desired tubular configuration.

  10. Rapid magnetic cell delivery for large tubular bioengineered constructs.

    PubMed

    Gonzalez-Molina, J; Riegler, J; Southern, P; Ortega, D; Frangos, C C; Angelopoulos, Y; Husain, S; Lythgoe, M F; Pankhurst, Q A; Day, R M

    2012-11-01

    Delivery of cells into tubular tissue constructs with large diameters poses significant spatial and temporal challenges. This study describes preliminary findings for a novel process for rapid and uniform seeding of cells onto the luminal surface of large tubular constructs. Fibroblasts, tagged with superparamagnetic iron oxide nanoparticles (SPION), were directed onto the luminal surface of tubular constructs by a magnetic field generated by a k4-type Halbach cylinder device. The spatial distribution of attached cells, as measured by the mean number of cells, was compared with a conventional, dynamic, rotational cell-delivery technique. Cell loading onto the constructs was measured by microscopy and magnetic resonance imaging. The different seeding techniques employed had a significant effect on the spatial distribution of the cells (p < 0.0001). The number of attached cells at defined positions within the same construct was significantly different for the dynamic rotation technique (p < 0.05). In contrast, no significant differences in the number of cells attached to the luminal surface were found between the defined positions on the construct loaded with the Halbach cylinder. The technique described overcomes limitations associated with existing cell-delivery techniques and is amenable to a variety of tubular organs where rapid loading and uniform distribution of cells for therapeutic applications are required. PMID:22696487

  11. An Improved Design of a Simple Tubular Reactor Experiment.

    ERIC Educational Resources Information Center

    Asfour, Abdul-Fattah A.

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment which: (1) examines the effect of residence time on conversion in a tubular flow reactor; and (2) compares the experimental conversions with those obtained from plug-flow and laminar-flow reactor models. (JN)

  12. Hemodynamic and tubular changes induced by contrast media.

    PubMed

    Caiazza, Antonella; Russo, Luigi; Sabbatini, Massimo; Russo, Domenico

    2014-01-01

    The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI. PMID:24678510

  13. Urinary Markers of Tubular Injury in Early Diabetic Nephropathy

    PubMed Central

    Fiseha, Temesgen; Tamir, Zemenu

    2016-01-01

    Diabetic nephropathy (DN) is a common and serious complication of diabetes associated with adverse outcomes of renal failure, cardiovascular disease, and premature mortality. Early and accurate identification of DN is therefore of critical importance to improve patient outcomes. Albuminuria, a marker of glomerular involvement in early renal damage, cannot always detect early DN. Thus, more sensitive and specific markers in addition to albuminuria are needed to predict the early onset and progression of DN. Tubular injury, as shown by the detection of tubular injury markers in the urine, is a critical component of the early course of DN. These urinary tubular markers may increase in diabetic patients, even before diagnosis of microalbuminuria representing early markers of normoalbuminuric DN. In this review we summarized some new and important urinary markers of tubular injury, such as neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver-type fatty acid binding protein (L-FABP), N-acetyl-beta-glucosaminidase (NAG), alpha-1 microglobulin (A1M), beta 2-microglobulin (B2-M), and retinol binding protein (RBP) associated with early DN. PMID:27293888

  14. Urinary Markers of Tubular Injury in Early Diabetic Nephropathy.

    PubMed

    Fiseha, Temesgen; Tamir, Zemenu

    2016-01-01

    Diabetic nephropathy (DN) is a common and serious complication of diabetes associated with adverse outcomes of renal failure, cardiovascular disease, and premature mortality. Early and accurate identification of DN is therefore of critical importance to improve patient outcomes. Albuminuria, a marker of glomerular involvement in early renal damage, cannot always detect early DN. Thus, more sensitive and specific markers in addition to albuminuria are needed to predict the early onset and progression of DN. Tubular injury, as shown by the detection of tubular injury markers in the urine, is a critical component of the early course of DN. These urinary tubular markers may increase in diabetic patients, even before diagnosis of microalbuminuria representing early markers of normoalbuminuric DN. In this review we summarized some new and important urinary markers of tubular injury, such as neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver-type fatty acid binding protein (L-FABP), N-acetyl-beta-glucosaminidase (NAG), alpha-1 microglobulin (A1M), beta 2-microglobulin (B2-M), and retinol binding protein (RBP) associated with early DN. PMID:27293888

  15. Hemodynamic and Tubular Changes Induced by Contrast Media

    PubMed Central

    Caiazza, Antonella; Russo, Luigi; Russo, Domenico

    2014-01-01

    The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI. PMID:24678510

  16. EGCG decreases binding of calcium oxalate monohydrate crystals onto renal tubular cells via decreased surface expression of alpha-enolase.

    PubMed

    Kanlaya, Rattiyaporn; Singhto, Nilubon; Thongboonkerd, Visith

    2016-06-01

    Crystal retention on tubular cell surface inside renal tubules is considered as the earliest and crucial step for kidney stone formation. Therapeutics targeting this step would cease the development of kidney stone. This study thus aimed to investigate the potential role of epigallocatechin-3-gallate (EGCG), a major antioxidant found in green tea leaves, in the reduction of calcium oxalate monohydrate (COM) crystal binding onto renal tubular cells. Pretreatment of the cells with EGCG for up to 6 h significantly diminished crystal-binding capability in a dose-dependent manner. Indirect immunofluorescence assay without and with cell permeabilization followed by laser-scanning confocal microscopy revealed that EGCG significantly reduced surface expression of alpha-enolase, whereas its intracellular level was increased. Western blot analysis confirmed such contradictory changes in membrane and cytosolic fractions of EGCG-treated cells, whereas the total level in whole cell lysate remained unchanged. Moreover, overexpression of surface alpha-enolase and enhancement of cell-crystal adhesion induced by 10 mM sodium oxalate were completely abolished by EGCG. Taken together, these data indicate that EGCG decreases binding of COM crystals onto renal tubular cells by decreasing the surface expression of alpha-enolase via re-localization or inhibition of alpha-enolase shuttling from the cytoplasm to the plasma membrane. These findings may also explain the effects of EGCG in reducing COM crystal deposition in previous animal models of kidney stone disease. Thus, EGCG may be useful for the prevention of new or recurrent stone formation. PMID:26898643

  17. Downregulation of renal tubular Wnt/β-catenin signaling by Dickkopf-3 induces tubular cell death in proteinuric nephropathy

    PubMed Central

    Wong, D W L; Yiu, W H; Wu, H J; Li, R X; Liu, Y; Chan, K W; Leung, J C K; Chan, L Y Y; Lai, K N; Tang, S C W

    2016-01-01

    Studies on the role of Wnt/β-catenin signaling in different forms of kidney disease have yielded discrepant results. Here, we report the biphasic change of renal β-catenin expression in mice with overload proteinuria in which β-catenin was upregulated at the early stage (4 weeks after disease induction) but abrogated at the late phase (8 weeks). Acute albuminuria was observed at 1 week after bovine serum albumin injection, followed by partial remission at 4 weeks that coincided with overexpression of renal tubular β-catenin. Interestingly, a rebound in albuminuria at 8 weeks was accompanied by downregulated tubular β-catenin expression and heightened tubular apoptosis. In addition, there was an inverse relationship between Dickkopf-3 (Dkk-3) and renal tubular β-catenin expression at these time points. In vitro, a similar trend in β-catenin expression was observed in human kidney-2 (HK-2) cells with acute (upregulation) and prolonged (downregulation) exposure to albumin. Induction of a proapoptotic phenotype by albumin was significantly enhanced by silencing β-catenin in HK-2 cells. Finally, Dkk-3 expression and secretion was increased after prolonged exposure to albumin, leading to the suppression of intracellular β-catenin signaling pathway. The effect of Dkk-3 on β-catenin signaling was confirmed by incubation with exogenous Dkk-3 in HK-2 cells. Taken together, these data suggest that downregulation of tubular β-catenin signaling induced by Dkk-3 has a detrimental role in chronic proteinuria, partially through the increase in apoptosis. PMID:27010856

  18. Diacylglycerol Kinase α Regulates Tubular Recycling Endosome Biogenesis and Major Histocompatibility Complex Class I Recycling*

    PubMed Central

    Xie, Shuwei; Naslavsky, Naava; Caplan, Steve

    2014-01-01

    Major histocompatibility complex class I (MHC I) presents intracellular-derived peptides to cytotoxic T lymphocytes and its subcellular itinerary is important in regulating the immune response. While a number of diacylglycerol kinase isoforms have been implicated in clathrin-dependent internalization, MHC I lacks the typical motifs known to mediate clathrin-dependent endocytosis. Here we show that depletion of diacylglycerol kinase α (DGKα), a kinase devoid of a clathrin-dependent adaptor protein complex 2 binding site, caused a delay in MHC I recycling to the plasma membrane without affecting the rate of MHC I internalization. We demonstrate that DGKα knock-down causes accumulation of intracellular and surface MHC I, resulting from decreased degradation. Furthermore, we provide evidence that DGKα is required for the generation of phosphatidic acid required for tubular recycling endosome (TRE) biogenesis. Moreover, we show that DGKα forms a complex with the TRE hub protein, MICAL-L1. Given that MICAL-L1 and the F-BAR-containing membrane-tubulating protein Syndapin2 associate selectively with phosphatidic acid, we propose a positive feedback loop in which DGKα generates phosphatidic acid to drive its own recruitment to TRE via its interaction with MICAL-L1. Our data support a novel role for the involvement of DGKα in TRE biogenesis and MHC I recycling. PMID:25248744

  19. Diabetes increases susceptibility of primary cultures of rat proximal tubular cells to chemically induced injury

    SciTech Connect

    Zhong Qing; Terlecky, Stanley R.; Lash, Lawrence H.

    2009-11-15

    Diabetic nephropathy is characterized by increased oxidative stress and mitochondrial dysfunction. In the present study, we prepared primary cultures of proximal tubular (PT) cells from diabetic rats 30 days after an ip injection of streptozotocin and compared their susceptibility to oxidants (tert-butyl hydroperoxide, methyl vinyl ketone) and a mitochondrial toxicant (antimycin A) with that of PT cells isolated from age-matched control rats, to test the hypothesis that PT cells from diabetic rats exhibit more cellular and mitochondrial injury than those from control rats when exposed to these toxicants. PT cells from diabetic rats exhibited higher basal levels of reactive oxygen species (ROS) and higher mitochondrial membrane potential, demonstrating that the PT cells maintain the diabetic phenotype in primary culture. Incubation with either the oxidants or mitochondrial toxicant resulted in greater necrotic and apoptotic cell death, greater evidence of morphological damage, greater increases in ROS, and greater decreases in mitochondrial membrane potential in PT cells from diabetic rats than in those from control rats. Pretreatment with either the antioxidant N-acetyl-L-cysteine or a catalase mimetic provided equivalent protection of PT cells from both diabetic and control rats. Despite the greater susceptibility to oxidative and mitochondrial injury, both cytoplasmic and mitochondrial glutathione concentrations were markedly higher in PT cells from diabetic rats, suggesting an upregulation of antioxidant processes in diabetic kidney. These results support the hypothesis that primary cultures of PT cells from diabetic rats are a valid model in which to study renal cellular function in the diabetic state.

  20. Renal proximal tubular cell fibronectin accumulation in response to glucose is polyol pathway dependent

    PubMed

    Morrisey; Steadman; Williams; Phillips

    1999-06-01

    Thickening and reduplication of the tubular basement membrane has been reported as an early event in diabetic nephropathy. In the current study we have examined the polar requirements of proximal tubular cells for the D-glucose stimulated accumulation of fibronectin. We also examined the mechanism by which glucose led to accumulation of fibronectin, with particular emphasis on the polyol pathway. Incubation of confluent monolayers of LLC-PK1 cells grown on tissue culture inserts with 25 mM D-glucose on either their apical or basolateral aspect, led to fibronectin accumulation in the basolateral compartment. This reached statistical significance 24 h following apical addition of glucose (2.7 fold increase compared to 5 mM D-glucose, p = 0.007, n = 6), and 12 h after the basolateral addition of glucose (2.54 fold increase compared to 5 mM D-glucose, p = 0.02, n = 6). The increase in fibronectin concentration in response to glucose was inhibited by the aldose reductase inhibitor sorbinil. At a dose of 100&mgr;M sorbinil there was 59% inhibition of fibronectin accumulation in response to glucose, 48 h after the addition of the inhibitor (4.76 +/- 1.4 vs 11.53 +/- 1.41, mean +/- SD, p = 0.01, n = 3). Exposure of cells to glucose at either their apical or basolateral aspect lead to accumulation of intracellular glucose and polyol pathway activation, as assessed by sorbitol accumulation. Accumulation of intracellular glucose and hence subsequent polyol pathway activation occurred independently of transport of glucose by either apical sodium linked glucose transporter (SLGT) or basolateral GLUT 1. The data demonstrate that fibronectin generation in response to glucose was non-polar in terms application of glucose, but polar in terms of fibronectin accumulation. Furthermore modulation of fibronectin was mediated by polyol pathway activation, and more specifically related to the metabolism of sorbitol to fructose. PMID:10354307

  1. Testing composite-to-metal tubular lap joints

    NASA Astrophysics Data System (ADS)

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

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

  2. Buckling characteristics of hypersonic aircraft wing tubular panels

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Shideler, John L.; Fields, Roger A.

    1986-01-01

    The buckling characteristics of Rene 41 tubular panels installed as wing panels on a hypersonic wing test structure (HWTS) were determined nondestructively through use of a force/stiffness technique. The nondestructive buckling tests were carried out under different combined load conditions and different temperature environments. Two panels were subsequently tested to buckling failure in a universal tension compression testing machine. In spite of some data scattering because of large extrapolations of data points resulting from termination of the test at a somewhat low applied load, the overall test data correlated fairly well with theoretically predicted buckling interaction curves. The structural efficiency of the tubular panels was slightly higher than that of the beaded panels which they replaced.

  3. Testing composite-to-metal tubular lap joints

    SciTech Connect

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

    1993-11-01

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

  4. Molecular interactions between albumin and proximal tubular cells.

    PubMed

    Brunskill, N J

    1998-01-01

    In glomerular diseases the filtration of excess proteins into the proximal tubule, together with their subsequent reabsorption may represent an important pathological mechanism underlying progressive renal scarring. The most prominent protein in glomerular filtrate, albumin, is reabsorbed by receptor-mediated endocytosis by proximal tubular cells. It binds both to scavenger-type receptors and to megalin in the proximal tubule. Some of these receptors appear to be shared with other cell types, particularly endothelial cells. The endocytic uptake of albumin is subjected to complex hormonal and enzymatic regulation. In addition to being reabsorbed in the proximal tubule, albumin may act as a signalling molecule in these cells, and may induce the expression of numerous pro-inflammatory genes. Modulation of the interaction of albumin with proximal tubular cells may eventually prove to be of therapeutic importance in the treatment of renal diseases. PMID:9807019

  5. [Primary distal renal tubular acidosis: a case report].

    PubMed

    Abdallah, Jihene Ben; Charfeddine, Bassem; Braham, Imen; Neffati, Souhir; Othmen, Leila Ben; Letaief, Affef; Smach, Mohamed Ali; Bourfifa, Zoheier; Dridi, Hedi; Limem, Khalifa

    2011-01-01

    The primary distal renal tubular acidosis is characterized biochemically by the inability of the kidney to produce appropriately acid urine in the presence of systemic metabolic acidosis or after acid loading (e.g. ammonium chloride). It is secondary to defective excretion of H(+) by the cells of the collecting duct. We report the observation of the child MC, 4-year-old, for whom the association of polyuria-polydipsia syndrome, a failure to thrive, nephrolithiasis, hypercalciuria, and especially a high urine pH in the presence of metabolic acidosis did evoke diagnosis of distal renal tubular acidosis. An urine acidification test with ammonium chloride was performed, the urinary pH was always higher than 5.5, thus confirming the diagnosis. PMID:21464016

  6. Dynamic model of microalgal production in tubular photobioreactors.

    PubMed

    Fernández, I; Acién, F G; Fernández, J M; Guzmán, J L; Magán, J J; Berenguel, M

    2012-12-01

    A dynamic model for microalgal culture is presented. The model takes into account the fluid-dynamic and mass transfer, in addition to biological phenomena, it being based on fundamental principles. The model has been calibrated and validated using data from a pilot-scale tubular photobioreactor but it can be extended to other designs. It can be used to determine, from experimental measurements, the values of characteristic parameters. The model also allows a simulation of the system's dynamic behaviour in response to solar radiation, making it a useful tool for design and operation optimization of photobioreactors. Moreover, the model permits the identification of local pH gradients, dissolved oxygen and dissolved carbon dioxide; that can damage microalgae growth. In addition, the developed model can map the different characteristic time scales of phenomena inside microalgae cultures within tubular photobioreactors, meaning it is a valuable tool in the development of advanced control strategies for microalgae cultures. PMID:23073105

  7. Phyllotactic transformations as plastic deformations of tubular crystals with defects

    NASA Astrophysics Data System (ADS)

    Beller, Daniel; Nelson, David

    Tubular crystals are 2D lattices in cylindrical topologies, which could be realized as assemblies of colloidal particles, and occur naturally in biological microtubules and in single-walled carbon nanotubes. Their geometry can be understood in the language of phyllotaxis borrowed from botany. We study the mechanics of plastic deformations in tubular crystals in response to tensile stress, as mediated by the formation and separation of dislocation pairs in a triangular lattice. Dislocation motion allows the growth of one phyllotactic arrangement at the expense of another, offering a low-energy, stepwise mode of plastic deformation in response to external stresses. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, dislocation glide. The crystal's bending modulus is found to produce simple but important corrections to the tube's deformation mechanics.

  8. An early Cambrian agglutinated tubular lophophorate with brachiopod characters

    PubMed Central

    Zhang, Z.-F.; Li, G.-X.; Holmer, L. E.; Brock, G. A.; Balthasar, U.; Skovsted, C. B.; Fu, D.-J.; Zhang, X.-L.; Wang, H.-Z.; Butler, A.; Zhang, Z.-L.; Cao, C.-Q.; Han, J.; Liu, J.-N.; Shu, D.-G.

    2014-01-01

    The morphological disparity of lophotrochozoan phyla makes it difficult to predict the morphology of the last common ancestor. Only fossils of stem groups can help discover the morphological transitions that occurred along the roots of these phyla. Here, we describe a tubular fossil Yuganotheca elegans gen. et sp. nov. from the Cambrian (Stage 3) Chengjiang Lagerstätte (Yunnan, China) that exhibits an unusual combination of phoronid, brachiopod and tommotiid (Cambrian problematica) characters, notably a pair of agglutinated valves, enclosing a horseshoe-shaped lophophore, supported by a lower bipartite tubular attachment structure with a long pedicle with coelomic space. The terminal bulb of the pedicle provided anchorage in soft sediment. The discovery has important implications for the early evolution of lophotrochozoans, suggesting rooting of brachiopods into the sessile lophotrochozoans and the origination of their bivalved bauplan preceding the biomineralization of shell valves in crown brachiopods. PMID:24828016

  9. Evacuated, displacement compression mold. [of tubular bodies from thermosetting plastics

    NASA Technical Reports Server (NTRS)

    Heier, W. C. (Inventor)

    1974-01-01

    A process of molding long thin-wall tubular bodies from thermosetting plastic molding compounds is described wherein the tubular body lengths may be several times the diameters. The process is accomplished by loading a predetermined quantity of molding compound into a female mold cavity closed at one end by a force mandrel. After closing the other end of the female mold with a balance mandrel, the loaded cavity is evacuated by applying a vacuum of from one-to-five mm pressure for a period of fifteen-to-thirty minutes. The mold temperature is raised to the minimum temperature at which the resin constituent of the compound will soften or plasticize and a pressure of 2500 psi is applied.

  10. Recovery of ammonia from swine manure using gas-permeable membranes: Effect of waste strength and pH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen recovery of swine manure was investigated using gas-permeable membranes. The process involved a continuous recirculation of an acidic solution through a tubular gas-permeable membrane submerged in a manure filled vessel. Ammonia contained in manure was concentrated in the acidic solution ...

  11. Optimal startup control of a jacketed tubular reactor.

    NASA Technical Reports Server (NTRS)

    Hahn, D. R.; Fan, L. T.; Hwang, C. L.

    1971-01-01

    The optimal startup policy of a jacketed tubular reactor, in which a first-order, reversible, exothermic reaction takes place, is presented. A distributed maximum principle is presented for determining weak necessary conditions for optimality of a diffusional distributed parameter system. A numerical technique is developed for practical implementation of the distributed maximum principle. This involves the sequential solution of the state and adjoint equations, in conjunction with a functional gradient technique for iteratively improving the control function.

  12. Tubular space truss structure for SKITTER 2 robot

    NASA Technical Reports Server (NTRS)

    Beecham, Richard; Dejulio, Linda; Delorme, Paul; Eck, Eric; Levy, Avi; Lowery, Joel; Radack, Joe; Sheffield, Randy; Stevens, Scott

    1988-01-01

    The Skitter 2 is a three legged transport vehicle designed to demonstrate the principle of a tripod walker in a multitude of environments. The tubular truss model of Skitter 2 is a proof of principal design. The model will replicate the operational capabilities of Skitter 2 including its ability to self-right itself. The project's focus was on the use of light weight tubular members in the final structural design. A strong design for the body was required as it will undergo the most intense loading. Triangular geometry was used extensively in the body, providing the required structural integrity and eliminating the need for cumbersome shear panels. Both the basic femur and tibia designs also relied on the strong geometry of the triangle. An intense literature search aided in the development of the most suitable weld techniques, joints, linkages, and materials required for a durable design. The hinge design features the use of spherical rod end bearings. In order to obtain a greater range of mobility in the tibia, a four-bar linkage was designed which attaches both to the femur and the tibia. All component designs, specifically the body, femur, and the tibia were optimized using the software package IDEAS 3.8A Supertab. The package provided essential deformation and stress analysis information on each component's design. The final structure incurred only a 0.0544 inch deflection in a maximum (worst case) loading situation. The highest stress experienced by any AL6061-T6 tubular member was 1920 psi. The structural integrity of the final design facilitated the use of Aluminum 6061-T6 tubing. The tubular truss structure of Skitter 2 is an effective and highly durable design. All facets of the design are structurally sound and cost effective.

  13. A tubular flux-switching permanent magnet machine

    NASA Astrophysics Data System (ADS)

    Wang, J.; Wang, W.; Clark, R.; Atallah, K.; Howe, D.

    2008-04-01

    The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.

  14. Mechanical models for the self-organization of tubular patterns

    PubMed Central

    2013-01-01

    Organogenesis, such as long tubule self-organization, requires long-range coordination of cell mechanics to arrange cell positions and to remodel the extracellular matrix. While the current mainstream in the field of tissue morphogenesis focuses primarily on genetics and chemical signaling, the influence of cell mechanics on the programming of patterning cues in tissue morphogenesis has not been adequately addressed. Here, we review experimental evidence and propose quantitative mechanical models by which cells can create tubular patterns. PMID:23719257

  15. Elastomer liners for geothermal tubulars Y267 EPDM Liner Program:

    SciTech Connect

    Hirasuna, A.R.; Davis, D.L.; Flickinger, J.E.; Stephens, C.A.

    1987-12-01

    The elastomer, Y267 EPDM, has been identified as a hydrothermally stable material which can operate at temperatures in excess of 320/sup 0/C. The goal of the Y267 Liner Program was to demonstrate the feasibility of using this material as a liner for mild steel tubulars to prevent or mitigate corrosion. If successful, the usage of EPDM lined pipe by the geothermal community may have a significant impact on operating costs and serve as a viable alternative to the use of alloyed tubulars. Tooling procedures were developed under this program to mold a 0.64 cm (0.25'') thick Y267 EPDM liner into a tubular test section 61 cm (2') in length and 19.1 cm (7.5'') in diameter (ID). A successful effort was made to identify a potential coupling agent to be used to bond the elastomer to the steel tubular wall. This agent was found to withstand the processing conditions associated with curing the elastomer at 288/sup 0/C and to retain a significant level of adhesive strength following hydrothermal testing in a synthetic brine at 260/sup 0/C for a period of 166 hours. Bonding tests were conducted on specimens of mild carbon steel and several alloys including Hastelloy C-276. An objective of the program was to field test the lined section of pipe mentioned above at a geothermal facility in the Imperial Valley. Though a test was conducted, problems encountered during the lining operation precluded an encouraging outcome. The results of the field demonstration were inconclusive. 6 refs., 13 figs., 13 tabs

  16. Inorganic fluoride. Divergent effects on human proximal tubular cell viability.

    PubMed Central

    Zager, R. A.; Iwata, M.

    1997-01-01

    Fluoride (F) is a widely distributed nephrotoxin with exposure potentially resulting from environmental pollution and from fluorinated anesthetic use (eg, isoflurane). This study sought to characterize some of the subcellular determinants of fluoride cytotoxicity and to determine whether subtoxic F exposure affects tubular cell vulnerability to superimposed ATP depletion and nephrotoxic attack. Human proximal tubular cells (HK-2) were cultured with differing amounts of NaF (0 to 20 mmol/L, overlapping with clinically relevant intrarenal/urinary levels after fluorinated anesthetic use). After completing 24-hour exposures, cell injury was determined (vital dye uptake). Fluoride effects on cell deacylation ([3]H-C20:4 release) and PLA2 activity were also assessed. To determine whether subtoxic F exposure alters tubular cell susceptibility to superimposed injury, cells were exposed to subtoxic NaF doses for 0 to 24 hours and then challenged with simulated ischemia (ATP depletion plus Ca2+ overload) or a clinically relevant nephrotoxic insult (myoglobin exposure). NaF induced dose-dependent cytotoxicity (up to approximately 90% vital dye uptake and increased [3H]C20:4 release). Extracellular Ca2+ chelation (EGTA) and PLA2 inhibitor therapy (aristolochic acid, dibucaine, or mepacrine) each conferred significant protective effects. When subtoxic NaF doses were applied, partial cytosolic PLA2 depletion rapidly developed (approximately 85% within 3 hours, determined on cell extracts). These partially PLA2-depleted cells were markedly resistant to ATP depletion/Ca2+ ionophore injury and to myoglobin-induced attack (approximately 50% decrease in cell death). We conclude that 1) F induces dose-dependent cytotoxicity in cultured human proximal tubular cells, 2) this occurs, in part, via Ca(2+)- and PLA2-dependent mechanism(s), 3) partial cytosolic PLA2 depletion subsequently results, and 4) subtoxic fluoride exposure can acutely increase cell resistance to further attack

  17. Tubular space truss structure for SKITTER 2 robot

    NASA Astrophysics Data System (ADS)

    Beecham, Richard; Dejulio, Linda; Delorme, Paul; Eck, Eric; Levy, Avi; Lowery, Joel; Radack, Joe; Sheffield, Randy; Stevens, Scott

    1988-05-01

    The Skitter 2 is a three legged transport vehicle designed to demonstrate the principle of a tripod walker in a multitude of environments. The tubular truss model of Skitter 2 is a proof of principal design. The model will replicate the operational capabilities of Skitter 2 including its ability to self-right itself. The project's focus was on the use of light weight tubular members in the final structural design. A strong design for the body was required as it will undergo the most intense loading. Triangular geometry was used extensively in the body, providing the required structural integrity and eliminating the need for cumbersome shear panels. Both the basic femur and tibia designs also relied on the strong geometry of the triangle. An intense literature search aided in the development of the most suitable weld techniques, joints, linkages, and materials required for a durable design. The hinge design features the use of spherical rod end bearings. In order to obtain a greater range of mobility in the tibia, a four-bar linkage was designed which attaches both to the femur and the tibia. All component designs, specifically the body, femur, and the tibia were optimized using the software package IDEAS 3.8A Supertab. The package provided essential deformation and stress analysis information on each component's design. The final structure incurred only a 0.0544 inch deflection in a maximum (worst case) loading situation. The highest stress experienced by any AL6061-T6 tubular member was 1920 psi. The structural integrity of the final design facilitated the use of Aluminum 6061-T6 tubing. The tubular truss structure of Skitter 2 is an effective and highly durable design. All facets of the design are structurally sound and cost effective.

  18. A permanent magnet tubular linear generator for wave energy conversion

    NASA Astrophysics Data System (ADS)

    Yu, Haitao; Liu, Chunyuan; Yuan, Bang; Hu, Minqiang; Huang, Lei; Zhou, Shigui

    2012-04-01

    A novel three-phase permanent magnet tubular linear generator (PMTLG) with Halbach array is proposed for the sea wave energy conversion. Non-linear axi-symmetrical finite element method (FEM) is implemented to calculate the magnetic fields along air-gap for different Halbach arrays of PMTLGs. The PMTLG characteristics are analyzed and the simulation results are validated by the experiment. An assistant tooth is implemented to greatly minimize the end and cogging effects which cause the oscillatory detent force.

  19. Tubular biomarkers to assess progression of diabetic nephropathy.

    PubMed

    Tramonti, Gianfranco; Kanwar, Yashpal S

    2011-05-01

    Despite aggressive management, many patients with diabetic nephropathy still develop end-stage renal disease. Accompanying tubulointerstitial damage is important in the progression of diabetic nephropathy. Markers of tubular damage, such as NGAL, KIM-1, and LFABP, have been proposed for monitoring the effectiveness of therapy. However, Nielsen et al. report a lack of an independent correlation between these biomarkers and glomerular filtration rate. Therefore, these markers seem to offer no improvement in the management of diabetic nephropathy. PMID:21527942

  20. Tissue cell assisted fabrication of tubular catalytic platinum microengines

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Moo, James Guo Sheng; Pumera, Martin

    2014-09-01

    We report a facile platform for mass production of robust self-propelled tubular microengines. Tissue cells extracted from fruits of banana and apple, Musa acuminata and Malus domestica, are used as the support on which a thin platinum film is deposited by means of physical vapor deposition. Upon sonication of the cells/Pt-coated substrate in water, microscrolls of highly uniform sizes are spontaneously formed. Tubular microengines fabricated with the fruit cell assisted method exhibit a fast motion of ~100 bodylengths per s (~1 mm s-1). An extremely simple and affordable platform for mass production of the micromotors is crucial for the envisioned swarms of thousands and millions of autonomous micromotors performing biomedical and environmental remediation tasks.We report a facile platform for mass production of robust self-propelled tubular microengines. Tissue cells extracted from fruits of banana and apple, Musa acuminata and Malus domestica, are used as the support on which a thin platinum film is deposited by means of physical vapor deposition. Upon sonication of the cells/Pt-coated substrate in water, microscrolls of highly uniform sizes are spontaneously formed. Tubular microengines fabricated with the fruit cell assisted method exhibit a fast motion of ~100 bodylengths per s (~1 mm s-1). An extremely simple and affordable platform for mass production of the micromotors is crucial for the envisioned swarms of thousands and millions of autonomous micromotors performing biomedical and environmental remediation tasks. Electronic supplementary information (ESI) available: Related video. See DOI: 10.1039/c4nr03720k

  1. Berberine activates Nrf2 nuclear translocation and inhibits apoptosis induced by high glucose in renal tubular epithelial cells through a phosphatidylinositol 3-kinase/Akt-dependent mechanism.

    PubMed

    Zhang, Xiuli; Liang, Dan; Lian, Xu; Jiang, Yan; He, Hui; Liang, Wei; Zhao, Yue; Chi, Zhi-Hong

    2016-06-01

    Apoptosis of tubular epithelial cells is a major feature of diabetic kidney disease, and hyperglycemia triggers the generation of free radicals and oxidant stress in tubular cells. Berberine (BBR) is identified as a potential anti-diabetic herbal medicine due to its beneficial effects on insulin sensitivity, glucose metabolism and glycolysis. In this study, the underlying mechanisms involved in the protective effects of BBR on high glucose-induced apoptosis were explored using cultured renal tubular epithelial cells (NRK-52E cells) and human kidney proximal tubular cell line (HK-2 cells). We identified the pivotal role of phosphatidylinositol 3-kinase (PI3K)/Akt in BBR cellular defense mechanisms and revealed the novel effect of BBR on nuclear factor (erythroid-derived 2)-related factor-2 (Nrf2) and heme oxygenase (HO)-1 in NRK-52E and HK-2 cells. BBR attenuated reactive oxygen species production, antioxidant defense (GSH and SOD) and oxidant-sensitive proteins (Nrf2 and HO-1), which also were blocked by LY294002 (an inhibitor of PI3K) in HG-treated NRK-52E and HK-2 cells. Furthermore, BBR improved mitochondrial function by increasing mitochondrial membrane potential. BBR-induced anti-apoptotic function was demonstrated by decreasing apoptotic proteins (cytochrome c, Bax, caspase3 and caspase9). All these findings suggest that BBR exerts the anti-apoptosis effects through activation of PI3K/Akt signal pathways and leads to activation of Nrf2 and induction of Nrf2 target genes, and consequently protecting the renal tubular epithelial cells from HG-induced apoptosis. PMID:26979714

  2. 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.

  3. Pediatric Tubular Pulmonary Heart Valve from Decellularized Engineered Tissue Tubes

    PubMed Central

    Reimer, Jay M.; Syedain, Zeeshan H.; Haynie, Bee H.T.; Tranquillo, Robert T.

    2015-01-01

    Pediatric patients account for a small portion of the heart valve replacements performed, but a pediatric pulmonary valve replacement with growth potential remains an unmet clinical need. Herein we report the first tubular heart valve made from two decellularized, engineered tissue tubes attached with absorbable sutures, which can meet this need, in principle. Engineered tissue tubes were fabricated by allowing ovine dermal fibroblasts to replace a sacrificial fibrin gel with an aligned, cell-produced collagenous matrix, which was subsequently decellularized. Previously, these engineered tubes became extensively recellularized following implantation into the sheep femoral artery. Thus, a tubular valve made from these tubes may be amenable to recellularization and, ideally, somatic growth. The suture line pattern generated three equi-spaced “leaflets” in the inner tube, which collapsed inward when exposed to back pressure, per tubular valve design. Valve testing was performed in a pulse duplicator system equipped with a secondary flow loop to allow for root distention. All tissue-engineered valves exhibited full leaflet opening and closing, minimal regurgitation (< 5%), and low systolic pressure gradients (< 2.5 mmHg) under pulmonary conditions. Valve performance was maintained under various trans-root pressure gradients and no tissue damage was evident after 2 million cycles of fatigue testing. PMID:26036175

  4. Gage for measuring fluted oil field tubular members

    SciTech Connect

    Case, W.A.; Burt, J.R.

    1987-03-17

    A gage is described for measuring the nominal diameter of an elongated tubular member having circumferentially spaced apart radially outwardly extending flutes and for calibrating the amount of wear to the flutes and predicting the future wear life of the tubular member. The gage comprises: a first gage part including a pair of spaced apart colinear elongated first handlebar halves with a generally semi-circular first half ring positioned between the first handlebar halves. The first half ring includes at least one flute engaging surface which includes stepped arcuate flute engaging portions positioned at radii from the center of the first ring half corresponding to different diameters to be measured; a second gage part including a pair of spaced apart colinear elongated second handlebar halves with a generally semicircular second half ring positioned between the second handlebar halves. The second half ring includes at least one flute engaging surface which includes stepped arcuate flute engaging portions positioned a radii from the center of the second ring half corresponding to different diameters to be measured. The number of flute engaging surfaces of the first and second ring halves is equal to the number of flutes on the tubular member; and a hinge pivotally connecting together one handlebar half of the first gage part to one handlebar half of the second gage part.

  5. Band gap in tubular pillar phononic crystal plate.

    PubMed

    Shu, Fengfeng; Liu, Yongshun; Wu, Junfeng; Wu, Yihui

    2016-09-01

    In this paper, a phononic crystal (PC) plate with tubular pillars is presented and investigated. The band structures and mode displacement profiles are calculated by using finite element method. The result shows that a complete band gap opens when the ratio of the pillar height to the plate thickness is about 1.6. However, for classic cylinder pillar structures, a band gap opens when the ratio is equal or greater than 3. A tubular pillar design with a void room in it enhances acoustic multiple scattering and gives rise to the opening of the band gap. In order to verify it, a PC structure with double tubular pillars different in size (one within the other) is introduced and a more than 2times band gap enlargement is observed. Furthermore, the coupling between the resonant mode and the plate mode around the band gap is characterized, as well as the effect of the geometrical parameters on the band gap. The behavior of such structure could be utilized to design a pillar PC with stronger structural stability and to enlarge band gaps. PMID:27376841

  6. A Tubular Biomaterial Construct Exhibiting a Negative Poisson's Ratio.

    PubMed

    Lee, Jin Woo; Soman, Pranav; Park, Jeong Hun; Chen, Shaochen; Cho, Dong-Woo

    2016-01-01

    Developing functional small-diameter vascular grafts is an important objective in tissue engineering research. In this study, we address the problem of compliance mismatch by designing and developing a 3D tubular construct that has a negative Poisson's ratio νxy (NPR). NPR constructs have the unique ability to expand transversely when pulled axially, thereby resulting in a highly-compliant tubular construct. In this work, we used projection stereolithography to 3D-print a planar NPR sheet composed of photosensitive poly(ethylene) glycol diacrylate biomaterial. We used a step-lithography exposure and a stitch process to scale up the projection printing process, and used the cut-missing rib unit design to develop a centimeter-scale NPR sheet, which was rolled up to form a tubular construct. The constructs had Poisson's ratios of -0.6 ≤ νxy ≤ -0.1. The NPR construct also supports higher cellular adhesion than does the construct that has positive νxy. Our NPR design offers a significant advance in the development of highly-compliant vascular grafts. PMID:27232181

  7. Developmental changes in renal tubular transport-an overview.

    PubMed

    Gattineni, Jyothsna; Baum, Michel

    2015-12-01

    The adult kidney maintains a constant volume and composition of extracellular fluid despite changes in water and salt intake. The neonate is born with a kidney that has a small fraction of the glomerular filtration rate of the adult and immature tubules that function at a lower capacity than that of the mature animal. Nonetheless, the neonate is also able to maintain a constant extracellular fluid volume and composition. Postnatal renal tubular development was once thought to be due to an increase in the transporter abundance to meet the developmental increase in glomerular filtration rate. However, postnatal renal development of each nephron segment is quite complex. There are isoform changes of several transporters as well as developmental changes in signal transduction that affect the capacity of renal tubules to reabsorb solutes and water. This review will discuss neonatal tubular function with an emphasis on the differences that have been found between the neonate and adult. We will also discuss some of the factors that are responsible for the maturational changes in tubular transport that occur during postnatal renal development. PMID:24253590

  8. Method and apparatus for forming flues on tubular stock

    DOEpatents

    Beck, D.E.; Carson, C.

    1979-12-21

    The present invention is directed to a die mechanism utilized for forming flues on long, relatively narrow tubular stock. These flues are formed by displacing a die from within the tubular stock through perforations previously drilled through the tubular stock at selected locations. The drawing of the die upsets the material to form the flue of the desired configuration. The die is provided with a lubricating system which enables the lubricant to be dispensed uniformly about the entire periphery of the die in contact with the material being upset so as to assure the formation of the flues. Further, the lubricant is dispensed from within the die onto the peripheral surface of the latter at pressures in the range of about 2000 to 10,000 psi so as to assure the adequate lubrication of the die during the drawing operation. By injecting the lubricant at such high pressures, low viscosity liquid, such as water and/or alcohol, may be efficiently used as a lubricant and also provides a mechanism by which the lubricant may be evaporated from the surface of the flues at ambient conditions so as to negate the cleansing operations previously required prior to joining the flues to other conduit mechanisms by fusion welding and the like.

  9. The rebirth of interest in renal tubular function.

    PubMed

    Lowenstein, Jerome; Grantham, Jared J

    2016-06-01

    The measurement of glomerular filtration rate by the clearance of inulin or creatinine has evolved over the past 50 years into an estimated value based solely on plasma creatinine concentration. We have examined some of the misconceptions and misunderstandings of the classification of renal disease and its course, which have followed this evolution. Furthermore, renal plasma flow and tubular function, which in the past were estimated by the clearance of the exogenous aryl amine, para-aminohippurate, are no longer measured. Over the past decade, studies in experimental animals with reduced nephron mass and in patients with reduced renal function have identified small gut-derived, protein-bound uremic retention solutes ("uremic toxins") that are poorly filtered but are secreted into the lumen by organic anion transporters (OATs) in the proximal renal tubule. These are not effectively removed by conventional hemodialysis or peritoneal dialysis. Residual renal function, urine produced in patients with advanced renal failure or undergoing dialysis treatment, may represent, at least in part, secretion of fluid and uremic toxins, such as indoxyl sulfate, mediated by proximal tubule OATs and might serve as a useful survival function. In light of this new evidence of the physiological role of proximal tubule OATs, we suggest that measurement of renal tubular function and renal plasma flow may be of considerable value in understanding and managing chronic kidney disease. Data obtained in normal subjects indicate that renal plasma flow and renal tubular function might be measured by the clearance of the endogenous aryl amine, hippurate. PMID:26936872

  10. Tubular transport and metabolism of cimetidine in chicken kidneys

    SciTech Connect

    Rennick, B.; Ziemniak, J.; Smith, I.; Taylor, M.; Acara, M.

    1984-02-01

    Renal tubular transport and renal metabolism of (/sup 14/C)cimetidine (CIM) were investigated by unilateral infusion into the renal portal circulation in chickens (Sperber technique). (/sup 14/C)CIM was actively transported at a rate 88% that of simultaneously infused p-aminohippuric acid, and its transport was saturable. The following organic cations competitively inhibited the tubular transport of (/sup 14/C)CIM with decreasing potency: CIM, ranitidine, thiamine, procainamide, guanidine and choline. CIM inhibited the transport of (/sup 14/C)thiamine, (/sup 14/C)amiloride and (/sup 14/C)tetraethylammonium. During CIM infusion, two renal metabolites, CIM sulfoxide and hydroxymethylcimetidine, were found in urine. When CIM sulfoxide was infused, its transport efficiency was 32% and not saturable. CIM sulfoxide did ot inhibit the simultaneous renal tubular transport of p-aminohippuric acid or tetraethylammonium. CIM is transported by the organic cation transport system and the kidney metabolizes CIM. Transport of CIM and other cationic drugs could produce a drug interaction to alter drug excretion.

  11. HCaRG Accelerates Tubular Repair after Ischemic Kidney Injury

    PubMed Central

    Matsuda, Hiroyuki; Lavoie, Julie L.; Gaboury, Louis; Hamet, Pavel

    2011-01-01

    The repair of the kidney after ischemia/reperfusion injury involves proliferation of proximal tubular epithelial cells as well as cell migration and differentiation. Immediately after reperfusion, expression of hypertension-related calcium-regulated gene (HCaRG/COMMD5) decreases, but its expression increases even higher than baseline during repair. HCaRG inhibits proliferation and accelerates wound healing and differentiation in cultured cells, but whether HCaRG can stimulate renal repair after ischemia/reperfusion injury is unknown. Here, transgenic mice overexpressing human HCaRG survived longer and recovered renal function faster than littermate controls after ischemia/reperfusion (64% versus 25% survival at 7 days). Proliferation of proximal tubular epithelial cells stopped earlier after ischemia/reperfusion injury, E-cadherin levels recovered more rapidly, and vimentin induction abated faster in transgenic mice. HCaRG overexpression also reduced macrophage infiltration and inflammation after injury. Taken together, these data suggest that HCaRG accelerates repair of renal proximal tubules by modulating cell proliferation of resident tubular epithelial cells and by facilitating redifferentiation. PMID:21921141

  12. ADVANCED HYDROGEN TRANSPORT MEMBRANES FOR VISION 21 FOSSIL FUEL PLANTS

    SciTech Connect

    Carl R. Evenson; Anthony F. Sammells; Richard T. Treglio; U. Balachandran; Richard N. Kleiner; James E. Stephan; Frank E. Anderson; Clive Brereton; Warren Wolfs; James Lockhart

    2004-10-21

    During this quarter, work was focused on characterizing the stability of layered composite membranes in a one hundred percent permeate environment. Permeation data was also collected on cermets as a function of thickness. A thin film deposition procedure was used to deposit dense thin BCY/Ni onto a tubular porous support. Thin film tubes were then tested for permeation at ambient pressure. Process flow diagrams were prepared for inclusion of hydrogen separation membranes into IGCC power plants under varying conditions. Finally, membrane promoted alkane dehydrogenation experiments were performed.

  13. Synthesis of mono- and bi-layer MFI zeolite films on macroporous alumina tubular supports: Application to nanofiltration

    NASA Astrophysics Data System (ADS)

    Said, Ali; Limousy, Lionel; Nouali, Habiba; Michelin, Laure; Halawani, Jalal; Toufaily, Joumana; Hamieh, Tayssir; Dutournié, Patrick; Daou, T. Jean

    2015-10-01

    This work is dedicated to the development of MFI-type structure zeolite films (single-layer or bilayer) on the internal layer of a specific macroporous alumina tubular support for nanofiltration applications. The bottom MFI layer was obtained by direct hydrothermal synthesis while a secondary growth method was used for the top MFI layer. A complete characterization of the obtained MFI membranes (single-layer or bilayer) is proposed using various techniques, such as X-ray diffraction, scanning electron microscopy, mercury porosimetry and nitrogen sorption measurements. Dense and highly crystallized films of MFI-type structure zeolite were obtained for both single-layer and bilayer MFI films. The total film thickness were around 7.1±0.5 μm and 14.5±1 μm for single-layer and bilayer MFI films respectively. The Si/Al molar ratio of the MFI films varied between 185 and 305 for single-layer and bilayer MFI films respectively. The hydraulic permeability of the tubular MFI membrane was achieved by the filtration of pure water. The hydraulic permeability of the single-layer and bilayer MFI membranes decreased rapidly at the beginning of the conditioning process, and stabilized at 1.08×10-14 m3 m-2 and 1.02×10-15 m3 m-2 after 15 h and the rejection rates of neutral solute (Vb 12) are 10% and 50% for the single-layer and bilayer MFI films respectively.

  14. 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

  15. Proximal tubular injury in Chinese herbs nephropathy: monitoring by neutral endopeptidase enzymuria.

    PubMed

    Nortier, J L; Deschodt-Lanckman, M M; Simon, S; Thielemans, N O; de Prez, E G; Depierreux, M F; Tielemans, C L; Richard, C; Lauwerys, R R; Bernard, A M; Vanherweghem, J L

    1997-01-01

    Neutral endopeptidase (NEP) is a 94 kDa ectoenzyme of the proximal tubule brush border, physiologically released into the urine with apical membrane fragments. As proximal tubular atrophy was a histological hallmark of Chinese herbs nephropathy (CHN), this study firstly determined renal excretion of NEP in healthy control subjects (N = 31), in patients with CHN (N = 26) and in women having consumed Chinese herbs and whose renal function was normal but running the risk of developing CHN (N = 27). Another patient group consisted of female patients with glomerular diseases (N = 12). At the same time, measurements of urinary microproteins (Clara cell protein, retinol binding protein, beta 2-microglobulin and alpha 1-microglobulin) were performed, as indicators of tubular dysfunction. Cell damage was estimated by the excretion of N-acetyl-beta-D-glucosaminidase (NAG). In the control group, the physiological NEP enzymuria was 43.1 micrograms/24 hr (geometric mean). In CHN patients, levels of urinary NEP were significantly decreased in those with moderate renal failure (26.7 micrograms/24 hr; N = 21; P < 0.05) and almost abolished in end-stage renal failure patients (4.35 micrograms/24 hr; N = 5; P < 0.05). In patients at risk as well as in patients with glomerular diseases, urinary NEP levels were not statistically different from those observed in control subjects (40.68 micrograms/24 hr and 48.5 micrograms/24 hr, respectively). Several degrees of tubular dysfunction and injury were noted in patients groups, as attested by increased urinary microproteins and NAG excretions. Considering the data from control and CHN patients, NEP enzymuria positively correlated with individual creatinine clearance values (r = 0.76; P = 0.0001) and negatively correlated with urinary microproteins levels (r = -0.55; P = 0.00001). Finally, NEP was regularly quantitated in the urine of 6 CHN patients for a period ranging from six months to two years and in 19 patients at risk during two years

  16. The molecular interactions between filtered proteins and proximal tubular cells in proteinuria.

    PubMed

    Baines, Richard J; Brunskill, Nigel J

    2008-01-01

    Proteinuria is associated with progressive chronic kidney disease and poor cardiovascular outcomes. Exposure of proximal tubular epithelial cells to excess proteins leads to the development of proteinuric nephropathy with tubular atrophy, interstitial inflammation and scarring. Numerous signalling pathways are activated in proximal tubular epithelial cells under proteinuric conditions resulting in gene transcription, altered growth and the secretion of inflammatory and profibrotic mediators. Megalin, the proximal tubular scavenger receptor for filtered macromolecules, has intrinsic signalling functions and may also link albumin to growth factor receptor signalling via regulated intramembrane proteolysis. It now seems that endocytosis is not always a prerequisite for albumin-evoked alterations in proximal tubular cell phenotype. Recent evidence shows the presence of other potential receptors for proteins, such as the neonatal Fc receptor and CD36, in the proximal tubular epithelium. PMID:18849618

  17. Exo70 Generates Membrane Curvature for Morphogenesis and Cell Migration

    PubMed Central

    Zhao, Yuting; Liu, Jianglan; Yang, Changsong; Capraro, Benjamin R.; Baumgart, Tobias; Bradley, Ryan P.; Ramakrishnan, N.; Xu, Xiaowei; Radhakrishnan, Ravi; Svitkina, Tatyana; Guo, Wei

    2013-01-01

    Dynamic shape changes of the plasma membrane are fundamental to many processes ranging from morphogenesis and cell migration to phagocytosis and viral propagation. Here we demonstrate that Exo70, a component of the exocyst complex, induces tubular membrane invaginations towards the lumen of synthetic vesicles in vitro and generates protrusions on the surface of cells. Biochemical analyses using Exo70 mutants and independent molecular dynamics simulations based on Exo70 structure demonstrate that Exo70 generates negative membrane curvature through an oligomerization-based mechanism. In cells, the membrane-deformation function of Exo70 is required for protrusion formation and directional cell migration. Exo70 thus represents a membrane-bending protein that may couple actin dynamics and plasma membrane remodeling for morphogenesis. PMID:23948253

  18. Separating hydrogen from coal gasification gases with alumina membranes

    SciTech Connect

    Egan, B.Z. ); Fain, D.E.; Roettger, G.E.; White, D.E. )

    1991-01-01

    Synthesis gas produced in coal gasification processes contains hydrogen, along with carbon monoxide, carbon dioxide, hydrogen sulfide, water, nitrogen, and other gases, depending on the particular gasification process. Development of membrane technology to separate the hydrogen from the raw gas at the high operating temperatures and pressures near exit gas conditions would improve the efficiency of the process. Tubular porous alumina membranes with mean pore radii ranging from about 9 to 22 {Angstrom} have been fabricated and characterized. Based on hydrostatic tests, the burst strength of the membranes ranged from 800 to 1600 psig, with a mean value of about 1300 psig. These membranes were evaluated for separating hydrogen and other gases. Tests of membrane permeabilities were made with helium, nitrogen, and carbon dioxide. Measurements were made at room temperature in the pressure range of 15 to 589 psi. Selected membranes were tested further with mixed gases simulating a coal gasification product gas. 5 refs., 7 figs.

  19. 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

  20. Macrophage matrix metalloproteinase-9 mediates epithelial-mesenchymal transition in vitro in murine renal tubular cells.

    PubMed

    Tan, Thian Kui; Zheng, Guoping; Hsu, Tzu-Ting; Wang, Ying; Lee, Vincent W S; Tian, Xinrui; Wang, Yiping; Cao, Qi; Wang, Ya; Harris, David C H

    2010-03-01

    As a rich source of pro-fibrogenic growth factors and matrix metalloproteinases (MMPs), macrophages are well-placed to play an important role in renal fibrosis. However, the exact underlying mechanisms and the extent of macrophage involvement are unclear. Tubular cell epithelial-mesenchymal transition (EMT) is an important contributor to renal fibrosis and MMPs to induction of tubular cell EMT. The aim of this study was to investigate the contribution of macrophages and MMPs to induction of tubular cell EMT. The murine C1.1 tubular epithelial cell line and primary tubular epithelial cells were cultured in activated macrophage-conditioned medium (AMCM) derived from lipopolysaccharide-activated J774 macrophages. MMP-9, but not MMP-2 activity was detected in AMCM. AMCM-induced tubular cell EMT in C1.1 cells was inhibited by broad-spectrum MMP inhibitor (GM6001), MMP-2/9 inhibitor, and in AMCM after MMP-9 removal by monoclonal Ab against MMP-9. AMCM-induced EMT in primary tubular epithelial cells was inhibited by MMP-2/9 inhibitor. MMP-9 induced tubular cell EMT in both C1.1 cells and primary tubular epithelial cells. Furthermore, MMP-9 induced tubular cell EMT in C1.1 cells to an extent similar to transforming growth factor-beta. Transforming growth factor-beta-induced tubular cell EMT in C1.1 cells was inhibited by MMP-2/9 inhibitor. Our in vitro study provides evidence that MMPs, specifically MMP-9, secreted by effector macrophages can induce tubular cell EMT and thereby contribute to renal fibrosis. PMID:20075196

  1. Method and tool for contracting tubular members by electro-hydraulic forming before hydroforming

    DOEpatents

    Golovashchenko, Sergey Fedorovich

    2011-03-15

    A tubular preform is contracted in an electro-hydraulic forming operation. The tubular preform is wrapped with one or more coils of wire and placed in a chamber of an electro-hydraulic forming tool. The electro-hydraulic forming tool is discharged to form a compressed area on a portion of the tube. The tube is then placed in a hydroforming tool that expands the tubular preform to form a part.

  2. BLOC-1 and BLOC-3 regulate VAMP7 cycling to and from melanosomes via distinct tubular transport carriers.

    PubMed

    Dennis, Megan K; Delevoye, Cédric; Acosta-Ruiz, Amanda; Hurbain, Ilse; Romao, Maryse; Hesketh, Geoffrey G; Goff, Philip S; Sviderskaya, Elena V; Bennett, Dorothy C; Luzio, J Paul; Galli, Thierry; Owen, David J; Raposo, Graça; Marks, Michael S

    2016-08-01

    Endomembrane organelle maturation requires cargo delivery via fusion with membrane transport intermediates and recycling of fusion factors to their sites of origin. Melanosomes and other lysosome-related organelles obtain cargoes from early endosomes, but the fusion machinery involved and its recycling pathway are unknown. Here, we show that the v-SNARE VAMP7 mediates fusion of melanosomes with tubular transport carriers that also carry the cargo protein TYRP1 and that require BLOC-1 for their formation. Using live-cell imaging, we identify a pathway for VAMP7 recycling from melanosomes that employs distinct tubular carriers. The recycling carriers also harbor the VAMP7-binding scaffold protein VARP and the tissue-restricted Rab GTPase RAB38. Recycling carrier formation is dependent on the RAB38 exchange factor BLOC-3. Our data suggest that VAMP7 mediates fusion of BLOC-1-dependent transport carriers with melanosomes, illuminate SNARE recycling from melanosomes as a critical BLOC-3-dependent step, and likely explain the distinct hypopigmentation phenotypes associated with BLOC-1 and BLOC-3 deficiency in Hermansky-Pudlak syndrome variants. PMID:27482051

  3. Glucose-Induced Down Regulation of Thiamine Transporters in the Kidney Proximal Tubular Epithelium Produces Thiamine Insufficiency in Diabetes

    PubMed Central

    Larkin, James R.; Zhang, Fang; Godfrey, Lisa; Molostvov, Guerman; Zehnder, Daniel; Rabbani, Naila; Thornalley, Paul J.

    2012-01-01

    Increased renal clearance of thiamine (vitamin B1) occurs in experimental and clinical diabetes producing thiamine insufficiency mediated by impaired tubular re-uptake and linked to the development of diabetic nephropathy. We studied the mechanism of impaired renal re-uptake of thiamine in diabetes. Expression of thiamine transporter proteins THTR-1 and THTR-2 in normal human kidney sections examined by immunohistochemistry showed intense polarised staining of the apical, luminal membranes in proximal tubules for THTR-1 and THTR-2 of the cortex and uniform, diffuse staining throughout cells of the collecting duct for THTR-1 and THTR-2 of the medulla. Human primary proximal tubule epithelial cells were incubated with low and high glucose concentration, 5 and 26 mmol/l, respectively. In high glucose concentration there was decreased expression of THTR-1 and THTR-2 (transporter mRNA: −76% and −53% respectively, p<0.001; transporter protein −77% and −83% respectively, p<0.05), concomitant with decreased expression of transcription factor specificity protein-1. High glucose concentration also produced a 37% decrease in apical to basolateral transport of thiamine transport across cell monolayers. Intensification of glycemic control corrected increased fractional excretion of thiamine in experimental diabetes. We conclude that glucose-induced decreased expression of thiamine transporters in the tubular epithelium may mediate renal mishandling of thiamine in diabetes. This is a novel mechanism of thiamine insufficiency linked to diabetic nephropathy. PMID:23285265

  4. The dental management of troublesome twos: renal tubular acidosis and rampant caries

    PubMed Central

    B, Sandhyarani; Huddar, Dayanand; Patil, Anil; Sankeshwari, Banashree

    2013-01-01

    Renal tubular acidosis is a group of disorders in which there is metabolic acidosis due to defect in renal tubular acidification mechanism to maintain normal plasma bicarbonate and blood pH. Irrespective of organ system involved, oral cavity often reflects the disease occurring anywhere in the body. Thus congenital chronic renal diseases, causing acid–base disturbances affects development and structure of the teeth. Chronic renal tubular acidosis causes enamel defects, dental caries, oral candidiasis, angular cheilitis, etc. We hereby present an unusual case report of a 4-year-old boy suffering from renal tubular acidosis associated with rampant caries, whose full mouth rehabilitation has been done. PMID:23667245

  5. High temperature helical tubular receiver for concentrating solar power system

    NASA Astrophysics Data System (ADS)

    Hossain, Nazmul

    In the field of conventional cleaner power generation technology, concentrating solar power systems have introduced remarkable opportunity. In a solar power tower, solar energy concentrated by the heliostats at a single point produces very high temperature. Falling solid particles or heat transfer fluid passing through that high temperature region absorbs heat to generate electricity. Increasing the residence time will result in more heat gain and increase efficiency. A novel design of solar receiver for both fluid and solid particle is approached in this paper which can increase residence time resulting in higher temperature gain in one cycle compared to conventional receivers. The helical tubular solar receiver placed at the focused sunlight region meets the higher outlet temperature and efficiency. A vertical tubular receiver is modeled and analyzed for single phase flow with molten salt as heat transfer fluid and alloy625 as heat transfer material. The result is compared to a journal paper of similar numerical and experimental setup for validating our modeling. New types of helical tubular solar receivers are modeled and analyzed with heat transfer fluid turbulent flow in single phase, and granular particle and air plug flow in multiphase to observe the temperature rise in one cyclic operation. The Discrete Ordinate radiation model is used for numerical analysis with simulation software Ansys Fluent 15.0. The Eulerian granular multiphase model is used for multiphase flow. Applying the same modeling parameters and boundary conditions, the results of vertical and helical receivers are compared. With a helical receiver, higher temperature gain of heat transfer fluid is achieved in one cycle for both single phase and multiphase flow compared to the vertical receiver. Performance is also observed by varying dimension of helical receiver.

  6. Tubular Overexpression of Gremlin Induces Renal Damage Susceptibility in Mice

    PubMed Central

    Droguett, Alejandra; Krall, Paola; Burgos, M. Eugenia; Valderrama, Graciela; Carpio, Daniel; Ardiles, Leopoldo; Rodriguez-Diez, Raquel; Kerr, Bredford; Walz, Katherina; Ruiz-Ortega, Marta; Egido, Jesus; Mezzano, Sergio

    2014-01-01

    A growing number of patients are recognized worldwide to have chronic kidney disease. Glomerular and interstitial fibrosis are hallmarks of renal progression. However, fibrosis of the kidney remains an unresolved challenge, and its molecular mechanisms are still not fully understood. Gremlin is an embryogenic gene that has been shown to play a key role in nephrogenesis, and its expression is generally low in the normal adult kidney. However, gremlin expression is elevated in many human renal diseases, including diabetic nephropathy, pauci-immune glomerulonephritis and chronic allograft nephropathy. Several studies have proposed that gremlin may be involved in renal damage by acting as a downstream mediator of TGF-β. To examine the in vivo role of gremlin in kidney pathophysiology, we generated seven viable transgenic mouse lines expressing human gremlin (GREM1) specifically in renal proximal tubular epithelial cells under the control of an androgen-regulated promoter. These lines demonstrated 1.2- to 200-fold increased GREM1 expression. GREM1 transgenic mice presented a normal phenotype and were without proteinuria and renal function involvement. In response to the acute renal damage cause by folic acid nephrotoxicity, tubule-specific GREM1 transgenic mice developed increased proteinuria after 7 and 14 days compared with wild-type treated mice. At 14 days tubular lesions, such as dilatation, epithelium flattening and hyaline casts, with interstitial cell infiltration and mild fibrosis were significantly more prominent in transgenic mice than wild-type mice. Tubular GREM1 overexpression was correlated with the renal upregulation of profibrotic factors, such as TGF-β and αSMA, and with increased numbers of monocytes/macrophages and lymphocytes compared to wild-type mice. Taken together, our results suggest that GREM1-overexpressing mice have an increased susceptibility to renal damage, supporting the involvement of gremlin in renal damage progression. This

  7. Reconstruction of Female Urethra with Tubularized Anterior Vaginal Flap

    PubMed Central

    Sawant, Ajit; Kumar, Vikash; Pawar, Prakash; Tamhankar, Ashwin; Bansal, Sumit; Kapadnis, Lomesh; Savalia, Abhishek

    2016-01-01

    Introduction Female urethral injury is a rare disease. Causes of urethral injuries are prolonged obstructed labour, gynaecological surgeries like vaginoplasty and post traumatic urethral injuries. The present study was conducted to evaluate outcome of female urethral reconstruction using tubularized anterior vaginal wall flap covered with fibroadipose martius flap and autologous fascia sling in patients with urethral loss. Aim Aim of study was to evaluate outcome of reconstruction of female urethra with tubularized anterior vaginal flap. Materials and Methods Retrospective analysis of all the patients with complete urethral loss was done from August 2008 to July 2015. Total seven patients were included in study. All patients presenting with total urethral loss were included. These patients were treated with tubularized anterior vaginal flap. Neourethra was covered with Martius labial flap and autologous fascia lata or rectus abdominis fascia sling. Most common cause of urethral loss was obstructed labour (57.1%). Postoperatively patients were assessed for continence, urine flow rate, ultrasound for upper urinary tract and post void residue. Results Mean operative time was 180 minutes (160-200 minutes) and Intraoperative blood loss was 220ml (170-260 ml). Mean postoperative hospital stay was eight days (seven to nine days) Mean post surgery maximum urine flow rate was more than 15ml/sec (6.7-18.2ml/sec) and mean post void residual urine was 22.5ml (10-50ml). Median follow-up time was 35 months. All patients were catheter free and continent post three weeks of surgery except one patient who developed mild stress urinary incontinence. One patient developed urethral stenosis which was managed by intermittent serial urethral dilatation. Conclusion Female neourethral reconstruction with tabularized anterior vaginal flap and autologous pubovaginal sling is feasible in patients of total urethral loss with success rate of approximately 86%. It should be considered in

  8. Distal renal tubular acidosis and amelogenesis imperfecta: A rare association.

    PubMed

    Ravi, P; Ekambaranath, T S; Arasi, S Ellil; Fernando, E

    2013-11-01

    Renal tubular acidosis (RTA) is characterized by a normal anion gap with hyperchloremic metabolic acidosis. Primary distal RTA (type I) is the most common RTA in children. Childhood presentation of distal RTA includes vomiting, failure to thrive, metabolic acidosis, and hypokalemia. Amelogenesis imperfecta (AI) represents a condition where the dental enamel and oral tissues are affected in an equal manner resulting in the hypoplastic or hypopigmented teeth. We report a 10-year-old girl, previously asymptomatic presented with the hypokalemic paralysis and on work-up found out to have type I RTA. The discoloration of teeth and enamel was diagnosed as AI. PMID:24339526

  9. Type 4 renal tubular acidosis in a kidney transplant recipient.

    PubMed

    Kulkarni, Manjunath

    2016-02-01

    We report a case of a 66-year-old diabetic patient who presented with muscle weakness 2 weeks after kidney transplantation. Her immunosuppressive regimen included tacrolimus, mycophenolate mofetil, and steroids. She was found to have hyperkalemia and normal anion gap metabolic acidosis. Tacrolimus levels were in therapeutic range. All other drugs such as beta blockers and trimethoprim - sulfamethoxazole were stopped. She did not respond to routine antikalemic measures. Further evaluation revealed type 4 renal tubular acidosis. Serum potassium levels returned to normal after starting sodium bicarbonate and fludrocortisone therapy. Though hyperkalemia is common in kidney transplant recipients, determining exact cause can guide specific treatment. PMID:27105603

  10. Ibuprofen-related renal tubular acidosis in pregnancy

    PubMed Central

    Mallett, Andrew; Lynch, Matthew; John, George T; Healy, Helen; Lust, Karin

    2011-01-01

    Ibuprofen-related renal tubular acidosis (RTA) has not been previously described in pregnancy but its occurrence outside of pregnancy is being increasingly described. In this case, a 34-year-old woman presented in the third trimester of pregnancy with Type 1 or distal RTA related to ibuprofen and codeine abuse. It was complicated by acute on chronic renal dysfunction and hypokalemia. Delivery at 37 weeks gestation due to concerns of evolving preeclampsia resulted in the birth of a healthy neonate. RTA and hypokalemia were remediated and ibuprofen and codeine abuse ceased. Some renal dysfunction however continued. Thorough and repeated history taking as well as vigilance for this condition is suggested.

  11. Excitation of symmetric surface wavesby electron tubular beams

    NASA Astrophysics Data System (ADS)

    Akimov, Yu A.; Olefir, V. P.; Azarenkov, N. A.

    2006-08-01

    The nonlinear theory of symmetric surface wave excitation by a low-density electron tubular beam in a cylindrical plasma-vacuum-metal waveguide is presented. A set of nonlinear equations is derived that describes the time evolution of the plasma-beam interaction. The influence of the beam and waveguide structure parameters on the saturation amplitude and excitation efficiency of the surface wave is investigated both numerically and analytically. Thermalization of the electron beam in the wave-fields is studied as well.

  12. Molecular Dynamics Study of Carbon Nanotubes/Polyamide Reverse Osmosis Membranes: Polymerization, Structure, and Hydration.

    PubMed

    Araki, Takumi; Cruz-Silva, Rodolfo; Tejima, Syogo; Takeuchi, Kenji; Hayashi, Takuya; Inukai, Shigeki; Noguchi, Toru; Tanioka, Akihiko; Kawaguchi, Takeyuki; Terrones, Mauricio; Endo, Morinobu

    2015-11-11

    Carbon nanotubes/polyamide (PA) nanocomposite thin films have become very attractive as reverse osmosis (RO) membranes. In this work, we used molecular dynamics to simulate the influence of single walled carbon nanotubes (SWCNTs) in the polyamide molecular structure as a model case of a carbon nanotubes/polyamide nanocomposite RO membrane. It was found that the addition of SWCNTs decreases the pore size of the composite membrane and increases the Na and Cl ion rejection. Analysis of the radial distribution function of water confined in the pores of the membranes shows that SWCNT+PA nanocomposite membranes also exhibit smaller clusters of water molecules within the membrane, thus suggesting a dense membrane structure (SWCNT+PA composite membranes were 3.9% denser than bare PA). The results provide new insights into the fabrication of novel membranes reinforced with tubular structures for enhanced desalination performance. PMID:26505521

  13. Toxicological significance of renal Bcrp: Another potential transporter in the elimination of mercuric ions from proximal tubular cells

    SciTech Connect

    Bridges, Christy C. Zalups, Rudolfs K.; Joshee, Lucy

    2015-06-01

    Secretion of inorganic mercury (Hg{sup 2+}) from proximal tubular cells into the tubular lumen has been shown to involve the multidrug resistance-associated protein 2 (Mrp2). Considering similarities in localization and substrate specificity between Mrp2 and the breast cancer resistance protein (Bcrp), we hypothesize that Bcrp may also play a role in the proximal tubular secretion of mercuric species. In order to test this hypothesis, the uptake of Hg{sup 2+} was examined initially using inside-out membrane vesicles containing Bcrp. The results of these studies suggest that Bcrp may be capable of transporting certain conjugates of Hg{sup 2+}. To further characterize the role of Bcrp in the handling of mercuric ions and in the induction of Hg{sup 2+}-induced nephropathy, Sprague–Dawley and Bcrp knockout (bcrp{sup −/−}) rats were exposed intravenously to a non-nephrotoxic (0.5 μmol·kg{sup −1}), a moderately nephrotoxic (1.5 μmol·kg{sup −1}) or a significantly nephrotoxic (2.0 μmol·kg{sup −1}) dose of HgCl{sub 2}. In general, the accumulation of Hg{sup 2+} was greater in organs of bcrp{sup −/−} rats than in Sprague–Dawley rats, suggesting that Bcrp may play a role in the export of Hg{sup 2+} from target cells. Within the kidney, cellular injury and necrosis was more severe in bcrp{sup −/−} rats than in controls. The pattern of necrosis, which was localized in the inner cortex and the outer stripe of the outer medulla, was significantly different from that observed in Mrp2-deficient animals. These findings suggest that Bcrp may be involved in the cellular export of select mercuric species and that its role in this export may differ from that of Mrp2. - Highlights: • Bcrp may mediate transport of mercury out of proximal tubular cells. • Hg-induced nephropathy was more severe in Bcrp knockout rats. • Bcrp and Mrp2 may differ in their ability to transport Hg.

  14. Protein Kinase C-δ Mediates Shedding of Angiotensin-Converting Enzyme 2 from Proximal Tubular Cells

    PubMed Central

    Xiao, Fengxia; Zimpelmann, Joseph; Burger, Dylan; Kennedy, Christopher; Hébert, Richard L.; Burns, Kevin D.

    2016-01-01

    Angiotensin-converting enzyme 2 (ACE2) degrades angiotensin (Ang) II to Ang-(1–7), and protects against diabetic renal injury. Soluble ACE2 fragments are shed from the proximal tubule, and appear at high levels in the urine with diabetes. High glucose-induced shedding of ACE2 from proximal tubular cells is mediated by the enzyme “a disintegrin and metalloproteinase-17″ (ADAM17). Here, we investigated the mechanism for constitutive shedding of ACE2. Mouse proximal tubular cells were cultured and ACE2 shedding into the media was assessed by enzyme activity assay and immunoblot analysis. Cells were incubated with pharmacologic inhibitors, or transfected with silencing (si) RNA. Incubation of proximal tubular cells with increasing concentrations of D-glucose stimulated ACE2 shedding, which peaked at 16 mM, while L-glucose (osmotic control) had no effect on shedding. In cells maintained in 7.8 mM D-glucose, ACE2 shedding was significantly inhibited by the pan-protein kinase C (PKC) competitive inhibitor sotrastaurin, but not by an inhibitor of ADAM17. Incubation of cells with the PKC-α and -β1-specific inhibitor Go6976, the PKC β1 and β2-specific inhibitor ruboxistaurin, inhibitors of matrix metalloproteinases-2,-8, and -9, or an inhibitor of ADAM10 (GI250423X) had no effect on basal ACE2 shedding. By contrast, the PKC-δ inhibitor rottlerin significantly inhibited both constitutive and high glucose-induced ACE2 shedding. Transfection of cells with siRNA directed against PKC-δ reduced ACE2 shedding by 20%, while knockdown of PKC-ε was without effect. These results indicate that constitutive shedding of ACE2 from proximal tubular cells is mediated by PKC-δ, which is also linked to high glucose-induced shedding. Targeting PKC-δ may preserve membrane-bound ACE2 in proximal tubule in disease states and diminish Ang II-stimulated adverse signaling. PMID:27313531

  15. Ceramide-Induced Apoptosis in Renal Tubular Cells: A Role of Mitochondria and Sphingosine-1-Phoshate

    PubMed Central

    Ueda, Norishi

    2015-01-01

    Ceramide is synthesized upon stimuli, and induces apoptosis in renal tubular cells (RTCs). Sphingosine-1 phosphate (S1P) functions as a survival factor. Thus, the balance of ceramide/S1P determines ceramide-induced apoptosis. Mitochondria play a key role for ceramide-induced apoptosis by altered mitochondrial outer membrane permeability (MOMP). Ceramide enhances oligomerization of pro-apoptotic Bcl-2 family proteins, ceramide channel, and reduces anti-apoptotic Bcl-2 proteins in the MOM. This process alters MOMP, resulting in generation of reactive oxygen species (ROS), cytochrome C release into the cytosol, caspase activation, and apoptosis. Ceramide regulates apoptosis through mitogen-activated protein kinases (MAPKs)-dependent and -independent pathways. Conversely, MAPKs alter ceramide generation by regulating the enzymes involving ceramide metabolism, affecting ceramide-induced apoptosis. Crosstalk between Bcl-2 family proteins, ROS, and many signaling pathways regulates ceramide-induced apoptosis. Growth factors rescue ceramide-induced apoptosis by regulating the enzymes involving ceramide metabolism, S1P, and signaling pathways including MAPKs. This article reviews evidence supporting a role of ceramide for apoptosis and discusses a role of mitochondria, including MOMP, Bcl-2 family proteins, ROS, and signaling pathways, and crosstalk between these factors in the regulation of ceramide-induced apoptosis of RTCs. A balancing role between ceramide and S1P and the strategy for preventing ceramide-induced apoptosis by growth factors are also discussed. PMID:25751724

  16. Helical arrays of U-shaped ATP synthase dimers form tubular cristae in ciliate mitochondria

    PubMed Central

    Mühleip, Alexander W.; Joos, Friederike; Wigge, Christoph; Frangakis, Achilleas S.; Kühlbrandt, Werner; Davies, Karen M.

    2016-01-01

    F1Fo-ATP synthases are universal energy-converting membrane protein complexes that synthesize ATP from ADP and inorganic phosphate. In mitochondria of yeast and mammals, the ATP synthase forms V-shaped dimers, which assemble into rows along the highly curved ridges of lamellar cristae. Using electron cryotomography and subtomogram averaging, we have determined the in situ structure and organization of the mitochondrial ATP synthase dimer of the ciliate Paramecium tetraurelia. The ATP synthase forms U-shaped dimers with parallel monomers. Each complex has a prominent intracrista domain, which links the c-ring of one monomer to the peripheral stalk of the other. Close interaction of intracrista domains in adjacent dimers results in the formation of helical ATP synthase dimer arrays, which differ from the loose dimer rows in all other organisms observed so far. The parameters of the helical arrays match those of the cristae tubes, suggesting the unique features of the P. tetraurelia ATP synthase are directly responsible for generating the helical tubular cristae. We conclude that despite major structural differences between ATP synthase dimers of ciliates and other eukaryotes, the formation of ATP synthase dimer rows is a universal feature of mitochondria and a fundamental determinant of cristae morphology. PMID:27402755

  17. Helical arrays of U-shaped ATP synthase dimers form tubular cristae in ciliate mitochondria.

    PubMed

    Mühleip, Alexander W; Joos, Friederike; Wigge, Christoph; Frangakis, Achilleas S; Kühlbrandt, Werner; Davies, Karen M

    2016-07-26

    F1Fo-ATP synthases are universal energy-converting membrane protein complexes that synthesize ATP from ADP and inorganic phosphate. In mitochondria of yeast and mammals, the ATP synthase forms V-shaped dimers, which assemble into rows along the highly curved ridges of lamellar cristae. Using electron cryotomography and subtomogram averaging, we have determined the in situ structure and organization of the mitochondrial ATP synthase dimer of the ciliate Paramecium tetraurelia. The ATP synthase forms U-shaped dimers with parallel monomers. Each complex has a prominent intracrista domain, which links the c-ring of one monomer to the peripheral stalk of the other. Close interaction of intracrista domains in adjacent dimers results in the formation of helical ATP synthase dimer arrays, which differ from the loose dimer rows in all other organisms observed so far. The parameters of the helical arrays match those of the cristae tubes, suggesting the unique features of the P. tetraurelia ATP synthase are directly responsible for generating the helical tubular cristae. We conclude that despite major structural differences between ATP synthase dimers of ciliates and other eukaryotes, the formation of ATP synthase dimer rows is a universal feature of mitochondria and a fundamental determinant of cristae morphology. PMID:27402755

  18. Prohibitin is associated with antioxidative protection in hypoxia/reoxygenation-induced renal tubular epithelial cell injury

    NASA Astrophysics Data System (ADS)

    Zhou, Tian-Biao; Qin, Yuan-Han; Lei, Feng-Ying; Huang, Wei-Fang; Drummen, Gregor P. C.

    2013-11-01

    Prohibitin is an evolutionary conserved and pleiotropic protein that has been implicated in various cellular functions, including proliferation, tumour suppression, apoptosis, transcription, and mitochondrial protein folding. We recently demonstrated that prohibitin downregulation results in increased renal interstitial fibrosis. Here we investigated the role of oxidative stress and prohibitin expression in a hypoxia/reoxygenation injury system in renal tubular epithelial cells with lentivirus-based delivery vectors to knockdown or overexpress prohibitin. Our results show that increased prohibitin expression was negatively correlated with reactive oxygen species, malon dialdehyde, transforming-growth-factor-β1, collagen-IV, fibronectin, and apoptosis (r = -0.895, -0.764, -0.798, -0.826, -0.817, -0.735 each P < 0.01), but positively correlated with superoxide dismutase, glutathione and mitochondrial membrane potential (r = 0.807, 0.815, 0.739; each P < 0.01). We postulate that prohibitin acts as a positive regulator of mechanisms that counteract oxidative stress and extracellular matrix accumulation and therefore has an antioxidative effect.

  19. Towards thermal design optimization of tubular digesters in cold climates: a heat transfer model.

    PubMed

    Perrigault, Thibault; Weatherford, Vergil; Martí-Herrero, Jaime; Poggio, Davide

    2012-11-01

    A cold climate, low cost, tubular digester is monitored and temperatures from different parts of the slurry, greenhouse, and adobe walls are presented, discussing the thermal performance of the digester. The slurry exhibits a vertical gradient of 6°C, with a mean value of 24.5°C, while the ambient temperature varies from 10°C to 30°C, showing the efficiency of the system as a solar heat collector with thermal inertia. A simple time-dependent thermal model is developed using inputs of solar radiation, wind velocity, ambient temperature, and digester geometry. The model outputs include temperatures of the slurry, the biogas, its holding membrane and the greenhouse air, wall and cover. Radiative, convective and conductive heat transfer phenomena are considered between all system elements. The model has 0.47°C (2%) standard error for the average slurry temperature. This model can be used to predict the influence of geometry and materials on the performance of the digester. PMID:22989653

  20. Lysophosphatidic acid-induced calcium mobilization and proliferation in kidney proximal tubular cells.

    PubMed

    Dixon, R J; Young, K; Brunskill, N J

    1999-02-01

    Patients with proteinuria tend to develop progressive renal disease with proximal tubular cell atrophy and interstitial scarring. It has been suggested that the nephrotoxicity of albuminuric states may be due to the protein molecule itself or by lipids, such as lysophosphatidic acid (LPA), that albumin carries. LPA was found to cause a transient increase in intracytoplasmic free Ca2+ ([Ca2+]i) in opossum kidney proximal tubule cells (OK) that was maximal at 100 microM LPA and was dose dependent with an EC50 of 2.6 x 10(-6) M. This Ca2+ mobilization was from both internal stores and across the plasma membrane and was pertussis toxin (PTX) insensitive. Treatment of OK cells with 100 microM LPA for 5 min was found to cause a twofold increase in [3H]thymidine incorporation and a three- to fivefold increase over control after 24 h. This was highly PTX sensitive and insensitive to pretreatment with the tyrosine kinase inhibitors genistein and herbimycin A. These findings may be of significance in the progression of renal disease and indicate the potential importance of lipids in modulating proximal tubule cell function and growth. PMID:9950949

  1. Models for coupling of salt and water transport; Proximal tubular reabsorption in Necturus kidney.

    PubMed

    Sackin, H; Boulpaep, E L

    1975-12-01

    Models for coupling of salt and water transport are developed with two important assumptions appropriate for leaky epithelia. (a) The tight junction is permeable to both sale and water. (b) Active Na transport into the lateral speces is assumed to occur uniformly along the length of the channel. The proposed models deal specifically with the intraepithelial mechanism of proximal tubular resbsorption in the Necturus kidney although they have implications for epithelial transport in the gallbladder and small intestine as well. The first model (continuous version) is similar to the standing gradient model devised by Diamond and Bossert but used different boundary conditions. In contrast to Diamond and Bossert's model, the predicted concentration profiles are relatively flat with no sizable gradients along the interspace. The second model (compartment version) expands Curran's model of epithelial salt and water transport by including additional compartments and considering both electrical and chemical driving forces for individual Na and Cl ions as well as hydraulic and osmotic driving forces for water. In both models, ion and water fluxes are investigated as a function of the transport parameters. The behavior of the models is consistent with previously suggested mechanisms for the control of net transport, particularly during saline diuresis. Under all conditions the predicted ratio of net solute to solvent flux, or emergent concentration, deviates from exact isotonicity (except when the basement membrane has an appreciable salt reflection coefficient). However, the degree of hypertonicity may be small enough to be experimentally indistinguishable from isotonic transport. PMID:1104761

  2. Renal mucinous tubular and spindle cell carcinoma: report of four cases and literature review.

    PubMed

    Wang, Hui; Xie, Jun; Lu, Changqing; Zhang, Dachuan; Jiang, Jingting

    2015-01-01

    Mucinous tubular and spindle cell carcinoma of the kidney (MTSCC-K) is an unusual renal tumor. It is important to increase the recognition of the clinicopathological features of MTSCC-K and improve its clinical and differential diagnosis. This report described four cases of MTSCC-K with clinical, imaging, and pathological examination and showed that the tumor boundaries of MTSCC-K were clear, and tumor cells arranged into tubules and cord-like beams, between which was lightly stained myxoid stroma. The tumor cells were smaller and cube- or oval-shaped, with single small eosinophilic nucleoli, low-grade nuclei, and little nuclear fission. The myxoid stroma was scattered around lymphocytes and plasma cells. Immunohistochemical markers including CK7, CD117, EMA (epithelial membrane antigen), vimentin, and CK8/18, showed positive expression in tumor cells, but the tumor cells were negative for CD10 and villin. The proliferation index of Ki-67 was 5-10%. Since MTSCC-K is a rare low-grade malignancy, with unique histological and immunohistochemical characteristics, it is important for clinicians and pathologists to have a defined awareness of this tumor type in order to decrease the rate of misdiagnosis. PMID:26045827

  3. Shear flow-induced formation of tubular cell protrusions in multiple myeloma cells

    PubMed Central

    Porat, Ziv; Yaron, Itamar; Katz, Ben-Zion; Kam, Zvi; Geiger, Benjamin

    2011-01-01

    Exposure of live cells to shear flow induces major changes in cell shape, adhesion to the extracellular matrix, and migration. In the present study, we show that exposure of cultured multiple myeloma (MM) cells to shear flow of 4–36 dynes/cm2 triggers the extension of long tubular protrusions (denoted FLow-Induced Protrusions, or FLIPs) in the direction of the flow. These FLIPs were found to be rich in actin, contain few or no microtubules and, apart from endoplasmic reticulum (ER)-like membranal structures, are devoid of organelles. Studying the dynamics of this process revealed that FLIPs elongate at their tips in a shear force-dependent manner, and retract at their bases. Examination of this force dependence revealed considerable heterogeneity in the mechanosensitivity of individual cells, most likely reflecting the diversity of the malignant B-cell population. The mechanisms underlying FLIP formation following mechanical perturbation, and their relevance to the cellular trafficking of MM cells, are discussed. PMID:21344380

  4. Nano-tubular cellulose for bioprocess technology development.

    PubMed

    Koutinas, Athanasios A; Sypsas, Vasilios; Kandylis, Panagiotis; Michelis, Andreas; Bekatorou, Argyro; Kourkoutas, Yiannis; Kordulis, Christos; Lycourghiotis, Alexis; Banat, Ibrahim M; Nigam, Poonam; Marchant, Roger; Giannouli, Myrsini; Yianoulis, Panagiotis

    2012-01-01

    Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in "cold pasteurization" processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc. PMID:22496794

  5. Recent progress in tubular solid oxide fuel cell technology

    SciTech Connect

    Singhal, S.C.

    1997-12-31

    The tubular design of solid oxide fuel cells (SOFCs) and the materials used therein have been validated by successful, continuous electrical testing over 69,000 h of early technology cells built on a calcia-stabilized zirconia porous support tube (PST). In the latest technology cells, the PST has been eliminated and replaced by a doped lanthanum manganite air electrode tube. These air electrode supported (AES) cells have shown a power density increase of about 33% with a significantly improved performance stability over the previously used PST type cells. These cells have also demonstrated the ability to thermally cycle over 100 times without any mechanical damage or performance loss. In addition, recent changes in processes used to fabricate these cells have resulted in significant cost reduction. This paper reviews the fabrication and performance of the state-of-the-art AES tubular cells. It also describes the materials and processing studies that are underway to further reduce the cell cost, and summarizes the recently built power generation systems that employed state-of-the-art AES cells.

  6. Advances in tubular solid oxide fuel cell technology

    SciTech Connect

    Singhal, S.C.

    1996-12-31

    The design, materials and fabrication processes for the earlier technology Westinghouse tubular geometry cell have been described in detail previously. In that design, the active cell components were deposited in the form of thin layers on a ceramic porous support tube (PST). The tubular design of these cells and the materials used therein have been validated by successful electrical testing for over 65,000 h (>7 years). In these early technology PST cells, the support tube, although sufficiently porous, presented an inherent impedance to air flow toward air electrode. In order to reduce such impedance to air flow, the wall thickness of the PST was first decreased from the original 2 mm (the thick-wall PST) to 1.2 mm (the thin-wall PST). The calcia-stabilized zirconia support tube has now been completely eliminated and replaced by a doped lanthanum manganite tube in state-of-the-art SOFCs. This doped lanthanum manganite tube is extruded and sintered to about 30 to 35 percent porosity, and serves as the air electrode onto which the other cell components are fabricated in thin layer form. These latest technology cells are designated as air electrode supported (AES) cells.

  7. A Polymeric Nanomedicine Diminishes Inflammatory Events in Renal Tubular Cells

    PubMed Central

    Ocaña-Salceda, Carlos; Sancho, Mónica; Orzáez, Mar; Messeguer, Angel; Ruiz-Ortega, Marta; Egido, Jesús; Vicent, María J.; Ortiz, Alberto; Ramos, Adrián M.

    2013-01-01

    The polyglutamic acid/peptoid 1 (QM56) nanoconjugate inhibits apoptosis by interfering with Apaf-1 binding to procaspase-9. We now describe anti-inflammatory properties of QM56 in mouse kidney and renal cell models. In cultured murine tubular cells, QM56 inhibited the inflammatory response to Tweak, a non-apoptotic stimulus. Tweak induced MCP-1 and Rantes synthesis through JAK2 kinase and NF-κB activation. Similar to JAK2 kinase inhibitors, QM56 inhibited Tweak-induced NF-κB transcriptional activity and chemokine expression, despite failing to inhibit NF-κB-p65 nuclear translocation and NF-κB DNA binding. QM56 prevented JAK2 activation and NF-κB-p65(Ser536) phosphorylation. The anti-inflammatory effect and JAK2 inhibition by QM56 were observed in Apaf-1−/− cells. In murine acute kidney injury, QM56 decreased tubular cell apoptosis and kidney inflammation as measured by down-modulations of MCP-1 and Rantes mRNA expression, immune cell infiltration and activation of the JAK2-dependent inflammatory pathway. In conclusion, QM56 has an anti-inflammatory activity which is independent from its role as inhibitor of Apaf-1 and apoptosis and may have potential therapeutic relevance. PMID:23300960

  8. Thermal conductivity modeling of core-shell and tubular nanowires.

    PubMed

    Yang, Ronggui; Chen, Gang; Dresselhaus, Mildred S

    2005-06-01

    The heteroepitaxial growth of crystalline core-shell nanostructures of a variety of materials has become possible in recent years, allowing the realization of various novel nanoscale electronic and optoelectronic devices. The increased surface or interface area will decrease the thermal conductivity of such nanostructures and impose challenges for the thermal management of such devices. In the meantime, the decreased thermal conductivity might benefit the thermoelectric conversion efficiency. In this paper, we present modeling results on the lattice thermal conductivity of core-shell and tubular nanowires along the wire axis direction using the phonon Boltzmann equation. We report the dependence of the thermal conductivity on the surface conditions and the core-shell geometry for silicon core-germanium shell and tubular silicon nanowires at room temperature. The results show that the effective thermal conductivity changes not only with the composition of the constituents but also with the radius of the nanowires and nanopores due to the nature of the ballistic phonon transport. The results in this work have implications for the design and operation of a variety of nanoelectronic devices, optoelectronic devices, and thermoelectric materials and devices. PMID:15943452

  9. Toward automated cochlear implant insertion using tubular manipulators

    NASA Astrophysics Data System (ADS)

    Granna, Josephine; Rau, Thomas S.; Nguyen, Thien-Dang; Lenarz, Thomas; Majdani, Omid; Burgner-Kahrs, Jessica

    2016-03-01

    During manual cochlear implant electrode insertion the surgeon is at risk to damage the intracochlear fine-structure, as the electrode array is inserted through a small opening in the cochlea blindly with little force-feedback. This paper addresses a novel concept for cochlear electrode insertion using tubular manipulators to reduce risks of causing trauma during insertion and to automate the insertion process. We propose a tubular manipulator incorporated into the electrode array composed of an inner wire within a tube, both elastic and helically shaped. It is our vision to use this manipulator to actuate the initially straight electrode array during insertion into the cochlea by actuation of the wire and tube, i.e. translation and slight axial rotation. In this paper, we evaluate the geometry of the human cochlea in 22 patient datasets in order to derive design requirements for the manipulator. We propose an optimization algorithm to automatically determine the tube set parameters (curvature, torsion, diameter, length) for an ideal final position within the cochlea. To prove our concept, we demonstrate that insertion can be realized in a follow-the-leader fashion for 19 out of 22 cochleas. This is possible with only 4 different tube/wire sets.

  10. Parallel, fluorous open-tubular chromatography using microstructured fibers.

    PubMed

    Daley, Adam B; Wright, Ramin D; Oleschuk, Richard D

    2011-04-01

    Although commonly used in gas chromatography, open-tubular columns for liquid chromatography have seen their development hindered by a number of factors both theoretical and practical. Requiring small diameters, great lengths and specialized detection systems to achieve a proper chromatographic response, columns of this sort have largely been ignored despite the highly desirable column performance an optimized system would provide. Here, we introduce the use of microstructured fibers (MSFs) as a platform for the development of multiplexed open-tubular liquid chromatography (OTLC) columns. The multiple, parallel silica channels presented by the MSF act as a promising substrate for an OTLC column, as they have diameters near the ideal range for interactions (1-3 μm), minimize flow-induced backpressure through their many uniform paths, and increase the loading capacity compared to a single capillary channel of similar size. Additionally, with outer diameters comparable to regular fused silica capillaries, MSFs can easily be employed in conventional chromatographic systems, eliminating the need for specialized equipment. Finally, MSF columns of this type can be functionalized using silane coupling techniques to allow the introduction of a wide variety of stationary phase chemistries. While in this report we explore the potential and limitations of fluorine-functionalized MSFs as OTLC columns, other stationary phase materials could easily be substituted by choosing appropriate silanization reagents. Particular attention here will be paid to the physical and performance characteristics of the fabricated columns, as well as avenues for their improvement and implementation. PMID:21435484

  11. Understanding shape and morphology of unusual tubular starch nanocrystals.

    PubMed

    Gong, Bei; Liu, Wenxia; Tan, Hua; Yu, Dehai; Song, Zhaoping; Lucia, Lucian A

    2016-10-20

    Starch nanocrystals (SNC) are aptly described as the insoluble degradation byproducts of starch granules that purportedly display morphologies that are platelet-like, round, square, and oval-like. In this work, we reported the preparation of SNC with unprecedented tubular structures through sulfuric acid hydrolysis of normal maize starch, subsequent exposure to ammonia and relaxation at 4°C. High-resolution transmission electron microscopy observation clearly proved that the SNCs possess tubular nanostructures with polygonal cross-section. After further reviewing the transformations of SNC by acid hydrolysis, ammonia treatment, and curing time at 4°C, a mechanism for T-SNC formation is suggested. It is conjectured that T-SNC gradually self-assembles by combination of smaller platelet-like/square nanocrystals likely loosely aggregated by starch molecular chains from residual amorphous regions. This work paves the way for the pursuit of new approaches for the preparation of starch-based nanomaterials possessing unique morphologies. PMID:27474612

  12. Nano-Tubular Cellulose for Bioprocess Technology Development

    PubMed Central

    Koutinas, Athanasios A.; Sypsas, Vasilios; Kandylis, Panagiotis; Michelis, Andreas; Bekatorou, Argyro; Kourkoutas, Yiannis; Kordulis, Christos; Lycourghiotis, Alexis; Banat, Ibrahim M.; Nigam, Poonam; Marchant, Roger; Giannouli, Myrsini; Yianoulis, Panagiotis

    2012-01-01

    Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in “cold pasteurization” processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc. PMID:22496794

  13. Tubular bamboo charcoal for anode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Li, Jun; Ye, Dingding; Zhu, Xun; Liao, Qiang; Zhang, Biao

    2014-12-01

    The anode material plays a significant role in determining the performance of microbial fuel cells (MFCs). In this study, the bamboo charcoal tube is proposed as a novel anode substrate by carbonizing the natural bamboo. Its surface functional groups, biocompatibility and internal resistance are thoroughly investigated. Performance of the MFCs with a conventional graphite tube anode and a bamboo charcoal tube anode is also compared. The results indicate that the tubular bamboo charcoal anode exhibits advantages over the graphite tube anode in terms of rougher surface, superior biocompatibility and smaller total internal resistance. Moreover, the X-ray photoelectron spectroscopy (XPS) analysis for the bamboo charcoal reveals that the introduced C-N bonds facilitate the electron transfer between the biofilm and electrodes. As a result, the MFC with a bamboo charcoal tube anode achieves a 50% improvement in the maximum power density over the graphite tube case. Furthermore, scale-up of the bamboo charcoal tube anode is demonstrated by employing a bundle of tubular bamboo charcoal to reach higher power output.

  14. Tubular dielectric elastomer actuator for active fluidic control

    NASA Astrophysics Data System (ADS)

    McCoul, David; Pei, Qibing

    2015-10-01

    We report a novel low-profile, biomimetic dielectric elastomer tubular actuator capable of actively controlling hydraulic flow. The tubular actuator has been established as a reliable tunable valve, pinching a secondary silicone tube completely shut in the absence of a fluidic pressure bias or voltage, offering a high degree of resistance against fluidic flow, and able to open and completely remove this resistance to flow with an applied low power actuation voltage. The system demonstrates a rise in pressure of ∼3.0 kPa when the dielectric elastomer valve is in the passive, unactuated state, and there is a quadratic fall in this pressure with increasing actuation voltage, until ∼0 kPa is reached at 2.4 kV. The device is reliable for at least 2000 actuation cycles for voltages at or below 2.2 kV. Furthermore, modeling of the actuator and fluidic system yields results consistent with the observed experimental dependence of intrasystem pressure on input flow rate, actuator prestretch, and actuation voltage. To our knowledge, this is the first actuator of its type that can control fluid flow by directly actuating the walls of a tube. Potential applications may include an implantable artificial sphincter, part of a peristaltic pump, or a computerized valve for fluidic or pneumatic control.

  15. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

    Obermeyer, Franklin D.; Middlebrooks, Willis B.; DeMario, Edmund E.

    1994-01-01

    Vibration dampener for dampening vibration of a tubular member, such as an instrumentation tube of the type found in nuclear reactor pressure vessels. The instrumentation tube is received in an outer tubular member, such as a guide thimble tube. The vibration dampener comprises an annular sleeve which is attachable to the inside surface of the guide thimble tube and which is sized to surround the instrumentation tube. Dimples are attached to the interior wall of the sleeve for radially supporting the instrumentation tube. The wall of the sleeve has a flexible spring member, which is formed from the wall, disposed opposite the dimples for biasing the instrumentation tube into abutment with the dimples. Flow-induced vibration of the instrumentation tube will cause it to move out of contact with the dimples and further engage the spring member, which will flex a predetermined amount and exert a reactive force against the instrumentation tube to restrain its movement. The amount by which the spring member will flex is less than the unrestrained amplitude of vibration of the instrumentation tube. The reactive force exerted against the instrumentation tube will be sufficient to return it to its original axial position within the thimble tube. In this manner, vibration of the instrumentation tube is dampened so that in-core physics measurements are accurate and so that the instrumentation tube will not wear against the inside surface of the guide thimble tube.

  16. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

    Obermeyer, F.D.; Middlebrooks, W.B.; DeMario, E.E.

    1994-10-18

    Vibration dampener for dampening vibration of a tubular member, such as an instrumentation tube of the type found in nuclear reactor pressure vessels is disclosed. The instrumentation tube is received in an outer tubular member, such as a guide thimble tube. The vibration dampener comprises an annular sleeve which is attachable to the inside surface of the guide thimble tube and which is sized to surround the instrumentation tube. Dimples are attached to the interior wall of the sleeve for radially supporting the instrumentation tube. The wall of the sleeve has a flexible spring member, which is formed from the wall, disposed opposite the dimples for biasing the instrumentation tube into abutment with the dimples. Flow-induced vibration of the instrumentation tube will cause it to move out of contact with the dimples and further engage the spring member, which will flex a predetermined amount and exert a reactive force against the instrumentation tube to restrain its movement. The amount by which the spring member will flex is less than the unrestrained amplitude of vibration of the instrumentation tube. The reactive force exerted against the instrumentation tube will be sufficient to return it to its original axial position within the thimble tube. In this manner, vibration of the instrumentation tube is dampened so that in-core physics measurements are accurate and so that the instrumentation tube will not wear against the inside surface of the guide thimble tube. 14 figs.

  17. Surface and interfacial creases in a bilayer tubular soft tissue

    NASA Astrophysics Data System (ADS)

    Razavi, Mir Jalil; Pidaparti, Ramana; Wang, Xianqiao

    2016-08-01

    Surface and interfacial creases induced by biological growth are common types of instability in soft biological tissues. This study focuses on the criteria for the onset of surface and interfacial creases as well as their morphological evolution in a growing bilayer soft tube within a confined environment. Critical growth ratios for triggering surface and interfacial creases are investigated both analytically and numerically. Analytical interpretations provide preliminary insights into critical stretches and growth ratios for the onset of instability and formation of both surface and interfacial creases. However, the analytical approach cannot predict the evolution pattern of the model after instability; therefore nonlinear finite element simulations are carried out to replicate the poststability morphological patterns of the structure. Analytical and computational simulation results demonstrate that the initial geometry, growth ratio, and shear modulus ratio of the layers are the most influential factors to control surface and interfacial crease formation in this soft tubular bilayer. The competition between the stretch ratios in the free and interfacial surfaces is one of the key driving factors to determine the location of the first crease initiation. These findings may provide some fundamental understanding in the growth modeling of tubular biological tissues such as esophagi and airways as well as offering useful clues into normal and pathological functions of these tissues.

  18. Numerical investigation of cavitation performance on bulb tubular turbine

    NASA Astrophysics Data System (ADS)

    Sun, L. G.; Guo, P. C.; Zheng, X. B.; Luo, X. Q.

    2016-05-01

    The cavitation flow phenomena may occur in the bulb tubular turbine at some certain operation conditions, which even decrease the performance of units and causes insatiably noise and vibration when it goes worse. A steady cavitating flow numerical simulations study is carried out on the bulb tubular unit with the same blade pitch angle and different guide vane openings by using the commercial code ANSYS CFX in this paper. The phenomena of cavitation induction areas and development process are obtained and draws cavitation performance curves. The numerical results show that the travelling bubble cavity is the main types of cavitation development over a wide operating range of discharge and this type of cavitation begins to sensitive to the value of cavitation number when the discharge exceeding a certain valve, in this condition, it can lead to a severe free bubble formation with the gradually decrement of cavitation number. The reported cavitation performance curves results indicate that the flow blockage incident would happen because of a mount of free bubble formation in the flow passage when the cavity developed to certain extend, which caused head drop behavior and power broken dramatically and influenced the output power.

  19. Additive manufacturing of patient-specific tubular continuum manipulators

    NASA Astrophysics Data System (ADS)

    Amanov, Ernar; Nguyen, Thien-Dang; Burgner-Kahrs, Jessica

    2015-03-01

    Tubular continuum robots, which are composed of multiple concentric, precurved, elastic tubes, provide more dexterity than traditional surgical instruments at the same diameter. The tubes can be precurved such that the resulting manipulator fulfills surgical task requirements. Up to now the only material used for the component tubes of those manipulators is NiTi, a super-elastic shape-memory alloy of nickel and titan. NiTi is a cost-intensive material and fabrication processes are complex, requiring (proprietary) technology, e.g. for shape setting. In this paper, we evaluate component tubes made of 3 different thermoplastic materials (PLA, PCL and nylon) using fused filament fabrication technology (3D printing). This enables quick and cost-effective production of custom, patient-specific continuum manipulators, produced on site on demand. Stress-strain and deformation characteristics are evaluated experimentally for 16 fabricated tubes of each thermoplastic with diameters and shapes equivalent to those of NiTi tubes. Tubes made of PCL and nylon exhibit properties comparable to those made of NiTi. We further demonstrate a tubular continuum manipulator composed of 3 nylon tubes in a transnasal, transsphenoidal skull base surgery scenario in vitro.

  20. Helical DNA origami tubular structures with various sizes and arrangements.

    PubMed

    Endo, Masayuki; Yamamoto, Seigi; Emura, Tomoko; Hidaka, Kumi; Morone, Nobuhiro; Heuser, John E; Sugiyama, Hiroshi

    2014-07-14

    We developed a novel method to design various helical tubular structures using the DNA origami method. The size-controlled tubular structures which have 192, 256, and 320 base pairs for one turn of the tube were designed and prepared. We observed the formation of the expected short tubes and unexpected long ones. Detailed analyses of the surface patterns of the tubes showed that the short tubes had mainly a left-handed helical structure. The long tubes mainly formed a right-handed helical structure and extended to the directions of the double helical axes as structural isomers of the short tubes. The folding pathways of the tubes were estimated by analyzing the proportions of short and long tubes obtained at different annealing conditions. Depending on the number of base pairs involved in one turn of the tube, the population of left-/right-handed and short/long tubes changed. The bending stress caused by the stiffness of the bundled double helices and the non-natural helical pitch determine the structural variety of the tubes. PMID:24888699

  1. Hierarchy in inorganic membranes.

    PubMed

    Caro, Juergen

    2016-06-13

    Thin films of a few μm thickness for particle filtration and gas separation cannot be applied as self-supporting layers since they are mechanically insufficiently strong. Therefore, these top layers for particle filtration and gas separation are usually deposited on porous mechanically strong supports with a hierarchical pore structure. To reduce the pressure drop of a gas stream over the membrane and to ensure high fluxes in filtration and gas separation, the cross section of the support is usually asymmetric or graded with a small thickness of the layer with the smallest pore size called the top layer. Since the pressure drop over a capillary with radius r is ∼r(4), the layer with the smallest pore size should be as thin as possible. The disk-like planar supports are usually prepared by sequential tape casting which is an expensive technology. Tubular supports with a hierarchical cross section can be prepared in one step by hollow fiber spinning, double mantle spinning or centrifugal casting. PMID:26466665

  2. 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

  3. 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

  4. Biochemical heterogeneity of skeletal-muscle microsomal membranes. Membrane origin, membrane specificity and fibre types

    PubMed Central

    Salviati, Giovanni; Volpe, Pompeo; Salvatori, Sergio; Betto, Romeo; Damiani, Ernesto; Margreth, Alfredo; Pasquali-Ronchetti, Ivonne

    1982-01-01

    1. Microsomes were isolated from rabbit fast-twitch and slow-twitch muscle and were separated into heavy and light fractions by centrifugation in a linear (0.3–2m) sucrose density gradient. The membrane origin of microsomal vesicles was investigated by studying biochemical markers of the sarcoplasmic-reticulum membranes and of surface and T-tubular membranes, as well as their freeze-fracture properties. 2. Polyacrylamide-gel electrophoresis showed differences in the Ca2+-dependent ATPase/calsequestrin ratio between heavy and light fractions, which were apparently consistent with their respective origin from cisternal and longitudinal sarcoplasmic reticulum, as well as unrelated differences, such as peptides specific to slow-muscle microsomes (mol.wts. 76000, 60000, 56000 and 45000). 3. Freeze-fracture electron microscopy of muscle microsomes demonstrated that vesicles truly derived from the sarcoplasmic reticulum, with an average density of 9nm particles on the concave face of about 3000/μm2 for both fast and slow muscle, were admixed with vesicles with particle densities below 1000/μm2. 4. As determined in the light fractions, the sarcoplasmic-reticulum vesicles accounted for 84% and 57% of the total number of microsomal vesicles, for fast and slow muscle respectively. These values agreed closely with the percentage values of Ca2+-dependent ATPase protein obtained by gel densitometry. 5. The T-tubular origin of vesicles with a smooth concave fracture face in slow-muscle microsomes is supported by their relative high content in total phospholipid and cholesterol, compared with the microsomes of fast muscle, and by other correlative data, such as the presence of (Na++K+)-dependent ATPase activity and of low amounts of Na+-dependent membrane phosphorylation. 6. Among intrinsic sarcoplasmic-reticulum membrane proteins, a proteolipid of mol.wt. 12000 is shown to be identical in the microsomes of both fast and slow muscle and the Ca2+-dependent ATPase to be

  5. Primary gradient defect distal renal tubular acidosis presenting as hypokalaemic periodic paralysis.

    PubMed

    Koul, P A; Wahid, A; Bhat, F A

    2005-07-01

    A 45 year old man presented with recurrent hypokalaemic paralysis. Laboratory investigations revealed renal tubular acidosis as the cause of the hypokalaemia, and dynamic tubular studies suggested a gradient defect as the underlying cause. The patient had associated dextrocardia. To our knowledge, this is the first report of this condition. PMID:15983101

  6. Expanded plug method for developing circumferential mechanical properties of tubular materials

    DOEpatents

    Hendrich, William Ray; McAfee, Wallace Jefferson; Luttrell, Claire Roberta

    2006-11-28

    A method for determining the circumferential properties of a tubular product, especially nuclear fuel cladding, utilizes compression of a polymeric plug within the tubular product to determine strain stress, yield stress and other properties. The process is especially useful in the determination of aging properties such as fuel rod embrittlement after long burn-down.

  7. Optimization of production conditions and material characteristics of tubular stabilizer bars

    NASA Astrophysics Data System (ADS)

    Muhr, R.

    1983-08-01

    Weight reduction of car tubular stabilizer bars is studied. Optimization of prematerial, forming and tempering procedures, and surface treatment are discussed. Steel qualities and production conditions were examined for feasibility with sample stabilizer bars. It is concluded that tubular stabilizer bars can be manufactured and practically used in cars. Tube diameters must not be too small, otherwise the weight saving is minimal.

  8. Low gas prices and rig count cut business for makers of oil country tubular goods

    SciTech Connect

    1995-09-01

    After years of scavenging used drill pipe and trying everything they could think of to make existing pipe last, contractors in the petroleum industry are buying more new pipe. Although supplies of tubular goods are growing tighter, the supply and demand curves haven`t met. However, while the market for drill pipe may be increasing, the market for other tubular goods is decreasing.

  9. 78 FR 77420 - Certain Oil Country Tubular Goods From the Republic of Turkey: Preliminary Negative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... Duty Investigations, 78 FR 45505 (July 29, 2013). \\2\\ Maverick Tube Corporation, United States Steel... International Trade Administration Certain Oil Country Tubular Goods From the Republic of Turkey: Preliminary... tubular goods (OCTG) from the Republic of Turkey (Turkey). The period of investigation is January 1,...

  10. Proximal tubular renal dysfunction or damage in HIV-infected patients.

    PubMed

    Del Palacio, María; Romero, Sara; Casado, José L

    2012-01-01

    Antiretroviral-associated toxicity, especially in the case of tenofovir plus boosted protease inhibitors, could affect different functions of the proximal renal tubule. Considering the long-term use of antiretroviral therapy and the concomitant presence of other risk factors, several degrees of proximal tubular toxicity, from chronic subclinical renal dysfunction to Fanconi syndrome, could be observed in HIV-infected patients. However, the clinical significance of isolated tubular dysfunction, in the short and long term, remains unclear. In addition, primary tubular abnormalities, even severe, may be missed until they affect the glomerular function. Therefore, there is a need for new biomarkers, not only based in serum creatinine and estimated glomerular filtration rates, that might help to identify tubular cell toxicity and predict the clinical outcome in HIV-infected patients. Increased values of urinary beta-2-microglobulin and retinol-binding protein, observed in up to 70% of patients, have been associated to tenofovir-associated mitochondrial dysfunction. Together with other tubular parameters or in isolation, both biomarkers could be useful for diagnosing proximal tubular toxicity. Other molecules, such as urinary kidney injury molecule- 1, neutrophil gelatinase associated lipocalin, or N-acetyl-b-D-glucosaminidase, could help to distinguish between tubular cell damage and dysfunction. Here, we review the current knowledge on tubular toxicity in HIV-infected patients on antiretroviral therapy. PMID:22833061

  11. 78 FR 52213 - Certain Oil Country Tubular Goods From India, Korea, the Philippines, Saudi Arabia, Taiwan...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-22

    ... Commission, Washington, DC, and by publishing the notice in the Federal Register of July 10, 2013 (78 FR... COMMISSION Certain Oil Country Tubular Goods From India, Korea, the Philippines, Saudi Arabia, Taiwan..., and Vietnam of certain oil country tubular goods, provided for primarily in subheadings 7304.29,...

  12. Electrospinning of small diameter 3-D nanofibrous tubular scaffolds with controllable nanofiber orientations for vascular grafts.

    PubMed

    Wu, Huijun; Fan, Jintu; Chu, Chih-Chang; Wu, Jun

    2010-12-01

    The control of nanofiber orientation in nanofibrous tubular scaffolds can benefit the cell responses along specific directions. For small diameter tubular scaffolds, however, it becomes difficult to engineer nanofiber orientation. This paper reports a novel electrospinning technique for the fabrication of 3-D nanofibrous tubular scaffolds with controllable nanofiber orientations. Synthetic absorbable poly-ε-caprolactone (PCL) was used as the model biomaterial to demonstrate this new electrospinning technique. Electrospun 3-D PCL nanofibrous tubular scaffolds of 4.5 mm in diameter with different nanofiber orientations (viz. circumferential, axial, and combinations of circumferential and axial directions) were successfully fabricated. The degree of nanofiber alignment in the electrospun 3-D tubular scaffolds was quantified by using the fast Fourier transform (FFT) analysis. The results indicated that excellent circumferential nanofiber alignment could be achieved in the 3-D nanofibrous PCL tubular scaffolds. The nanofibrous tubular scaffolds with oriented nanofibers had not only directional mechanical property but also could facilitate the orientation of the endothelial cell attachment on the fibers. Multiple layers of aligned nanofibers in different orientations can produce 3-D nanofibrous tubular scaffolds of different macroscopic properties. PMID:20890639

  13. 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.

  14. Efficiency and temperature dependence of water removal by membrane dryers.

    PubMed

    Leckrone, K J; Hayes, J M

    1997-03-01

    The vapor pressure of water in equilibrium with sorption sites within a Nafion membrane is given by log P(WN) = -3580/T + 10.01, where P(WN) is expressed in Torr and T is the membrane temperature, in kelvin. The efficiency of dryers based on selective permeation of water through Nafion can thus be enhanced by cooling the membrane. Residual water in effluents exceeds equilibrium levels if insufficient time is allowed for water to diffuse to the membrane surface as gas passes through the dryer. For tubular configurations, this limitation can be avoided if L > or = Fc(10(3.8)/120 pi D), where L is the length of the tubular membrane, in centimeters, Fc is the gas flow rate, in mL/ min, and D is the diffusion coefficient for water in the carrier gas at the operating temperature of the dryer, in cm2/s. An efficient dryer that at room temperature dries gas to a dew point of -61 degrees C is described; the same dryer maintained at 0 degrees C yields a dew point of -80 degrees C and removes water as effectively as Mg(ClO4)2 or a dry ice/acetone slush. The use of Nafion membranes to construct devices capable of delivering gas streams with low but precisely controlled humidities is discussed. PMID:11536807

  15. Efficiency and temperature dependence of water removal by membrane dryers

    NASA Technical Reports Server (NTRS)

    Leckrone, K. J.; Hayes, J. M.

    1997-01-01

    The vapor pressure of water in equilibrium with sorption sites within a Nafion membrane is given by log P(WN) = -3580/T + 10.01, where P(WN) is expressed in Torr and T is the membrane temperature, in kelvin. The efficiency of dryers based on selective permeation of water through Nafion can thus be enhanced by cooling the membrane. Residual water in effluents exceeds equilibrium levels if insufficient time is allowed for water to diffuse to the membrane surface as gas passes through the dryer. For tubular configurations, this limitation can be avoided if L > or = Fc(10(3.8)/120 pi D), where L is the length of the tubular membrane, in centimeters, Fc is the gas flow rate, in mL/ min, and D is the diffusion coefficient for water in the carrier gas at the operating temperature of the dryer, in cm2/s. An efficient dryer that at room temperature dries gas to a dew point of -61 degrees C is described; the same dryer maintained at 0 degrees C yields a dew point of -80 degrees C and removes water as effectively as Mg(ClO4)2 or a dry ice/acetone slush. The use of Nafion membranes to construct devices capable of delivering gas streams with low but precisely controlled humidities is discussed.

  16. Efficiency and temperature dependence of water removal by membrane dryers

    SciTech Connect

    Leckrone, K.J.; Hayes, J.M.

    1997-03-01

    The vapor pressure of water in equilibrium with sorption sites within a Nafion membrane is given by log P{sub WN} = -3580/T + 10.01, where P{sub WN} is expressed in Torr and T is the membrane temperature, in kelvin. The efficiency of dryers based on selective permeation of water through Nafion can thus be enhanced by cooling the membrane. Residual water in effluents exceeds equilibrium levels if insufficient time is allowed for water to diffuse to the membrane surface as gas passes through the dryer. For tubular configurations, this limitation can be avoided if L > F{sub c}(10{sup 3.8}/120{pi}D), where L is the length of the tubular membrane, in centimeters, F{sub c} is the gas flow rate, in mL/min, and D is the diffusion coefficient for water in the carrier gas at the operating temperature of the dryer, in cm{sup 2}/s. An efficient dryer that at room temperature dries gas to a dew point of -61 {degree}C is described; the same dryer maintained at 0 {degree}C yields a dew point of -80 {degree}C and removes water as effectively as Mg(ClO{sub 4}){sub 2} or a dry ice/acetone slush. The use of Nafion membranes to construct devices capable of delivering gas streams with low but precisely controlled humidities is discussed. 41 refs., 6 figs., 3 tabs.

  17. Excitability of the T-tubular system in rat skeletal muscle: roles of K+ and Na+ gradients and Na+-K+ pump activity.

    PubMed

    Nielsen, O B; Ørtenblad, N; Lamb, G D; Stephenson, D G

    2004-05-15

    Strenuous exercise causes an increase in extracellular [K(+)] and intracellular Na(+) ([Na(+)](i)) of working muscles, which may reduce sarcolemma excitability. The excitability of the sarcolemma is, however, to some extent protected by a concomitant increase in the activity of muscle Na(+)-K(+) pumps. The exercise-induced build-up of extracellular K(+) is most likely larger in the T-tubules than in the interstitium but the significance of the cation shifts and Na(+)-K(+) pump for the excitability of the T-tubular membrane and the voltage sensors is largely unknown. Using mechanically skinned fibres, we here study the role of the Na(+)-K(+) pump in maintaining T-tubular function in fibres with reduced chemical K(+) gradient. The Na(+)-K(+) pump activity was manipulated by changing [Na(+)](i). The responsiveness of the T-tubules was evaluated from the excitation-induced force production of the fibres. Compared to control twitch force in fibres with a close to normal intracellular [K(+)] ([K(+)](i)), a reduction in [K(+)](i) to below 60 mM significantly reduced twitch force. Between 10 and 50 mM Na(+), the reduction in force depended on [Na(+)](i), the twitch force at 40 mM K(+) being 22 +/- 4 and 54 +/- 9% (of control force) at a [Na(+)](i) of 10 and 20 mM, respectively (n= 4). Double pulse stimulation of fibres at low [K(+)](i) showed that although elevated [Na(+)](i) increased the responsiveness to single action potentials, it reduced the capacity of the T-tubules to respond to high frequency stimulation. It is concluded that a reduction in the chemical gradient for K(+), as takes place during intensive exercise, may depress T-tubular function, but that a concomitant exercise-induced increase in [Na(+)](i) protects T-tubular function by stimulating the Na(+)-K(+) pump. PMID:15034125

  18. Complex Dynamic Development of Poliovirus Membranous Replication Complexes

    PubMed Central

    Nair, Vinod; Hansen, Bryan T.; Hoyt, Forrest H.; Fischer, Elizabeth R.; Ehrenfeld, Ellie

    2012-01-01

    Replication of all positive-strand RNA viruses is intimately associated with membranes. Here we utilize electron tomography and other methods to investigate the remodeling of membranes in poliovirus-infected cells. We found that the viral replication structures previously described as “vesicles” are in fact convoluted, branching chambers with complex and dynamic morphology. They are likely to originate from cis-Golgi membranes and are represented during the early stages of infection by single-walled connecting and branching tubular compartments. These early viral organelles gradually transform into double-membrane structures by extension of membranous walls and/or collapsing of the luminal cavity of the single-membrane structures. As the double-membrane regions develop, they enclose cytoplasmic material. At this stage, a continuous membranous structure may have double- and single-walled membrane morphology at adjacent cross-sections. In the late stages of the replication cycle, the structures are represented mostly by double-membrane vesicles. Viral replication proteins, double-stranded RNA species, and actively replicating RNA are associated with both double- and single-membrane structures. However, the exponential phase of viral RNA synthesis occurs when single-membrane formations are predominant in the cell. It has been shown previously that replication complexes of some other positive-strand RNA viruses form on membrane invaginations, which result from negative membrane curvature. Our data show that the remodeling of cellular membranes in poliovirus-infected cells produces structures with positive curvature of membranes. Thus, it is likely that there is a fundamental divergence in the requirements for the supporting cellular membrane-shaping machinery among different groups of positive-strand RNA viruses. PMID:22072780

  19. Deducing the symmetry of helical assemblies: Applications to membrane proteins.

    PubMed

    Coudray, Nicolas; Lasala, Ralph; Zhang, Zhening; Clark, Kathy M; Dumont, Mark E; Stokes, David L

    2016-08-01

    Helical reconstruction represents a convenient and powerful approach for structure determination of macromolecules that assemble into helical arrays. In the case of membrane proteins, formation of tubular crystals with helical symmetry represents an attractive alternative, especially when their small size precludes the use of single-particle analysis. An essential first step for helical reconstruction is to characterize the helical symmetry. This process is often daunting, due to the complexity of helical diffraction and to the low signal-to-noise ratio in images of individual assemblies. Furthermore, the large diameters of the tubular crystals produced by membrane proteins exacerbates the innate ambiguities that, if not resolved, will produce incorrect structures. In this report, we describe a set of tools that can be used to eliminate ambiguities and to validate the choice of symmetry. The first approach increases the signal-to-noise ratio along layer lines by incoherently summing data from multiple helical assemblies, thus producing several candidate indexing schemes. The second approach compares the layer lines from images with those from synthetic models built with the various candidate schemes. The third approach uses unit cell dimensions measured from collapsed tubes to distinguish between these candidate schemes. These approaches are illustrated with tubular crystals from a boron transporter from yeast, Bor1p, and a β-barrel channel from the outer membrane of E. coli, OmpF. PMID:27255388

  20. Dysfunctional tubular endoplasmic reticulum constitutes a pathological feature of Alzheimer’s disease

    PubMed Central

    Sharoar, Md. Golam; Shi, Qi; Ge, Yingying; He, Wanxia; Hu, Xiangyou; Perry, George; Zhu, Xiongwei; Yan, Riqiang

    2015-01-01

    Pathological features in Alzheimer’s brains include mitochondrial dysfunction and dystrophic neurites (DNs) in areas surrounding amyloid plaques. Using a mouse model that overexpresses reticulon 3 (RTN3) and spontaneously develops age-dependent hippocampal DNs, here we report that DNs contain both RTN3 and REEPs, topologically similar proteins that can shape tubular endoplasmic reticulum (ER). Importantly, ultrastructural examinations of such DNs revealed gradual accumulation of tubular ER in axonal termini, and such abnormal tubular ER inclusion is found in areas surrounding amyloid plaques in biopsy samples from AD brains. Functionally, abnormally clustered tubular ER induces enhanced mitochondrial fission in the early stages of DN formation and eventual mitochondrial degeneration at later stages. Furthermore, such DNs are abrogated when RTN3 is ablated in aging and AD mouse models. Hence, abnormally clustered tubular ER can be pathogenic in brain regions: disrupting mitochondrial integrity, inducing DNs formation and impairing cognitive function in AD and aging brains PMID:26619807

  1. Renal Function in Diabetic Disease Models: The Tubular System in the Pathophysiology of the Diabetic Kidney

    PubMed Central

    Vallon, Volker; Thomson, Scott C.

    2013-01-01

    Diabetes mellitus affects the kidney in stages. At the onset of diabetes mellitus, in a subset of diabetic patients the kidneys grow large, and glomerular filtration rate (GFR) becomes supranormal, which are risk factors for developing diabetic nephropathy later in life. This review outlines a pathophysiological concept that focuses on the tubular system to explain these changes. The concept includes the tubular hypothesis of glomerular filtration, which states that early tubular growth and sodium-glucose cotransport enhance proximal tubule reabsorption and make the GFR supranormal through the physiology of tubuloglomerular feedback. The diabetic milieu triggers early tubular cell proliferation, but the induction of TGF-β and cyclin-dependent kinase inhibitors causes a cell cycle arrest and a switch to tubular hypertrophy and a senescence-like phenotype. Although this growth phenotype explains unusual responses like the salt paradox of the early diabetic kidney, the activated molecular pathways may set the stage for tubulointerstitial injury and diabetic nephropathy. PMID:22335797

  2. Dysfunctional tubular endoplasmic reticulum constitutes a pathological feature of Alzheimer's disease.

    PubMed

    Sharoar, M G; Shi, Q; Ge, Y; He, W; Hu, X; Perry, G; Zhu, X; Yan, R

    2016-09-01

    Pathological features in Alzheimer's brains include mitochondrial dysfunction and dystrophic neurites (DNs) in areas surrounding amyloid plaques. Using a mouse model that overexpresses reticulon 3 (RTN3) and spontaneously develops age-dependent hippocampal DNs, here we report that DNs contain both RTN3 and REEPs, topologically similar proteins that can shape tubular endoplasmic reticulum (ER). Importantly, ultrastructural examinations of such DNs revealed gradual accumulation of tubular ER in axonal termini, and such abnormal tubular ER inclusion is found in areas surrounding amyloid plaques in biopsy samples from Alzheimer's disease (AD) brains. Functionally, abnormally clustered tubular ER induces enhanced mitochondrial fission in the early stages of DN formation and eventual mitochondrial degeneration at later stages. Furthermore, such DNs are abrogated when RTN3 is ablated in aging and AD mouse models. Hence, abnormally clustered tubular ER can be pathogenic in brain regions: disrupting mitochondrial integrity, inducing DNs formation and impairing cognitive function in AD and aging brains. PMID:26619807

  3. Facile fabrication of Ag dendrite-integrated anodic aluminum oxide membrane as effective three-dimensional SERS substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Cong-yun; Lu, Ya; Zhao, Bin; Hao, Yao-wu; Liu, Ya-qing

    2016-07-01

    A novel surface enhanced Raman scattering (SERS)-active substrate has been successfully developed, where Ag-dendrites are assembled on the surface and embedded in the channels of anodic aluminum oxide (AAO) membrane, via electrodeposition in AgNO3/PVP aqueous system. Reaction conditions were systematically investigated to attain the best Raman enhancement. The growth mechanism of Ag dendritic nanostructures has been proposed. The Ag dendrite-integrated AAO membrane with unique hierarchical structures exhibits high SERS activity for detecting rhodamine 6G with a detection limit as low as 1 × 10-11 M. Furthermore, the three-dimensional (3D) substrates display a good reproducibility with the average intensity variations at the major Raman peak less than 12%. Most importantly, the 3D SERS substrates without any surface modification show an outstanding SERS response for the molecules with weak affinity for noble metal surfaces. The potential application for the detection of polycyclic aromatic hydrocarbons (PAHs) was evaluated with fluoranthene as Raman target molecule and a sensitive SERS detection with a limit down to 10-8 M was reached. The 3D SERS-active substrate shows promising potential for rapid detection of trace organic pollutants even weak affinity molecules in the environment.

  4. Efficiency of sunlight utilization: tubular versus flat photobioreactors

    PubMed

    Tredici; Zittelli

    1998-01-20

    The light saturation effect imposes a serious limitation on the efficiency with which solar energy can be utilized in outdoor algal cultures. One solution proposed to reduce the intensity of incident solar radiation and overcome the light saturation effect is "spatial dilution of light" (i.e., distribution of the impinging photon flux on a greater photosynthetic surface area), but consistent experimental data supporting a significant positive influence of spatial light dilution on the productivity and the photosynthetic efficiency of outdoor algal cultures have never been reported. We used a coiled tubular reactor and compared a near-horizontal straight tubular reactor and a near-horizontal flat panel in outdoor cultivation of the cyanobacterium Arthrospira (Spirulina) platensis under defined operating conditions for optimum productivity. The photosynthetic efficiency achieved in the tubular systems was significantly higher because their curved surface "diluted" the impinging solar radiation and thus reduced the light saturation effect. This interpretation was supported by the results of experiments carried out in the laboratory under continuous artificial illumination using both a flat and a curved chamber reactor. The study also showed that, when the effect of light saturation is eliminated or reduced, productivity and solar irradiance are linearly correlated even at very high diurnal irradiance values, and supported findings that outdoor algal cultures are light-limited even during bright summer days. It was also observed that, besides improving the photosynthetic efficiency of the culture, spatial dilution of light also leads to higher growth rates and lowers the cellular content of accessory pigments; that is, it reduces mutual shading in the culture. The inadequacy of using volumetric productivity as the sole criterion for comparing reactors of different surface-to-volume ratio and of the areal productivity for evaluating the performance of elevated

  5. Ceramic membranes for high temperature hydrogen separation

    SciTech Connect

    Fain, D.E.; Roettger, G.E.

    1996-08-01

    Ceramic gas separation membranes can provide very high separation factors if the pore size is sufficiently small to separate gas molecules by molecular sieving and if oversized pores are adequately limited. Ceramic membranes typically have some pores that are substantially larger than the mean pore size and that should be regarded as defects. To assess the effects of such defects on the performance of ceramic membranes, a simple mathematical model has been developed to describe flow through a gas separation membrane that has a primary mode of flow through very small pores but that has a secondary mode of flow through undesirably large pores. This model permits separation factors to be calculated for a specified gas pair as a function of the molecular weights and molecular diameters of the gases, the membrane pore diameter, and the diameter and number of defects. This model will be described, and key results from the model will be presented. The separation factors of the authors membranes continue to be determined using a permeance test system that measures flows of pure gases through a membrane at temperatures up to 275{degrees}C. A primary goal of this project for FY 1996 is to develop a mixed gas separation system for measuring the separation efficiency of membranes at higher temperatures. Performance criteria have been established for the planned mixed gas separation system and design of the system has been completed. The test system is designed to measure the separation efficiency of membranes at temperatures up to 600{degrees}C and pressures up to 100 psi by separating the constituents of a gas mixture containing hydrogen. The system will accommodate the authors typical experimental membrane that is tubular and has a diameter of about 9 mm and a length of about 23 cm. The design of the new test system and its expected performance will be discussed.

  6. Preparations of an inorganic-framework proton exchange nanochannel membrane

    NASA Astrophysics Data System (ADS)

    Yan, X. H.; Jiang, H. R.; Zhao, G.; Zeng, L.; Zhao, T. S.

    2016-09-01

    In this work, a proton exchange membrane composed of straight and aligned proton conducting nanochannels is developed. Preparation of the membrane involves the surface sol-gel method assisted with a through-hole anodic aluminum oxide (AAO) template to form the framework of the PEM nanochannels. A monomolecular layer (SO3Hsbnd (CH2)3sbnd Sisbnd (OCH3)3) is subsequently added onto the inner surfaces of the nanochannels to shape a proton-conducting pathway. Straight nanochannels exhibit long range order morphology, contributing to a substantial improvement in the proton mobility and subsequently proton conductivity. In addition, the nanochannel size can be altered by changing the surface sol-gel condition, allowing control of the active species/charge carrier selectivity via pore size exclusion. The proton conductivity of the nanochannel membrane is reported as high as 11.3 mS cm-1 at 70 °C with a low activation energy of 0.21 eV (20.4 kJ mol-1). First-principle calculations reveal that the activation energy for proton transfer is impressively low (0.06 eV and 0.07 eV) with the assistance of water molecules.

  7. Atypical distal renal tubular acidosis confirmed by mutation analysis.

    PubMed

    Weber, S; Soergel, M; Jeck, N; Konrad, M

    2000-12-01

    In autosomal dominant distal renal tubular acidosis type I (dRTA) impaired hydrogen ion secretion is associated with metabolic acidosis, hyperchloremic hypokalemia, hypercalciuria, nephrocalcinosis, and/or nephrolithiasis. A retardation of growth is commonly observed. In this report we present a family with autosomal dominant dRTA with an atypical and discordant clinical picture. The father presented with severe nephrocalcinosis, nephrolithiasis, and isosthenuria but metabolic acidosis was absent. His 6-year-old daughter, however, suffered from metabolic acidosis, hypokalemia, and hypercalciuria. In addition, sonography revealed multiple bilateral renal cysts but no nephrocalcinosis. Mutation analysis of the AE1 gene coding for the renal Cl-/HCO3(-)-exchanger AE1 displayed a heterozygous Arg589Cys exchange in both patients but not in the healthy family members. This point mutation is frequently associated with autosomal dominant dRTA. Diagnosis of autosomal dominant dRTA is supported in this family by results of AE1 mutation analysis. PMID:11149111

  8. A new alternative mechanism in glioblastoma vascularization: tubular vasculogenic mimicry

    PubMed Central

    Boisselier, Blandine; Peglion, Florent; Rousseau, Audrey; Colin, Carole; Idbaih, Ahmed; Marie, Yannick; Mokhtari, Karima; Thomas, Jean-Léon; Eichmann, Anne; Delattre, Jean-Yves; Maniotis, Andrew J.; Sanson, Marc

    2010-01-01

    Glioblastoma is one of the most angiogenic human tumours and endothelial proliferation is a hallmark of the disease. A better understanding of glioblastoma vasculature is needed to optimize anti-angiogenic therapy that has shown a high but transient efficacy. We analysed human glioblastoma tissues and found non-endothelial cell-lined blood vessels that were formed by tumour cells (vasculogenic mimicry of the tubular type). We hypothesized that CD133+ glioblastoma cells presenting stem-cell properties may express pro-vascular molecules allowing them to form blood vessels de novo. We demonstrated in vitro that glioblastoma stem-like cells were capable of vasculogenesis and endothelium-associated genes expression. Moreover, a fraction of these glioblastoma stem-like cells could transdifferentiate into vascular smooth muscle-like cells. We describe here a new mechanism of alternative glioblastoma vascularization and open a new perspective for the antivascular treatment strategy. PMID:20375132

  9. Scavenging energy from human motion with tubular dielectric polymer

    NASA Astrophysics Data System (ADS)

    Jean-Mistral, Claire; Basrour, Skandar

    2010-04-01

    Scavenging energy from human motion is a challenge to supply low consumption systems for sport or medical applications. A promising solution is to use electroactive polymers and especially dielectric polymers to scavenge mechanical energy during walk. In this paper, we present a tubular dielectric generator which is the first step toward an integration of these structures into textiles. For a 10cm length and under a strain of 100%, the structure is able to scavenge 1.5μJ for a poling voltage of 200V and up to 40μJ for a poling voltage of 1000V. A 30cm length structure is finally compared to our previous planar structure, and the power management module for those structures is discussed.

  10. Electrical Modulation of the Local Conduction at Oxide Tubular Interfaces

    SciTech Connect

    Hsieh, Ying-Hui; Strelcov, Evgheni; Jia-Ming, Liou; Chia-Ying, Shen; Yi-Chun, Chen; Kalinin, Sergei V; Ying-Hao, Chu

    2013-01-01

    Hetero-interfaces between complex oxides have sparked considerable interest due to their fascinating physical properties and offer new possibilities for next-generation electronic devices. The key to realize practical applications is the control through external stimulus. In this study, we take the self-assembled BiFeO3-CoFe2O4 hetero-interface as a model system to demonstrate the non-volatile electric control of the local conduction at the complex oxide tubular interface. The fundamental mechanism behind this modulation was explored based on static and dynamic conducting atomic force microscopy. We found the movement of oxygen vacancies in the BiFeO3-CoFe2O4 heterostructure is the key to drive this intriguing behavior. This study delivers a possibility of designing new device for next-generation electronic devices.

  11. [Diagnostic difficulties in a case of constricted tubular visual field].

    PubMed

    Dogaru, Oana-Mihaela; Rusu, Monica; Hâncu, Dacia; Horvath, Kárin

    2013-01-01

    In the paper below we present the clinical case of a 48 year old female with various symptoms associated with functional visual disturbance -constricted tubular visual fields, wich lasts from 6 years; the extensive clinical and paraclinical ophthalmological investigations ruled out the presence of an organic disorder. In the present, we suspect a diagnosis of hysteria, still uncertain, wich represented over time a big challenge in psychology and ophthalmology. The mechanisms and reasons for hysteria are still not clear and it could represent a fascinating research theme. The tunnel, spiral or star-shaped visual fields are specific findings in hysteria for patients who present visual disturbance. The question of whether or not a patient with hysterical visual impairment can or cannot "see" is still unresolved. PMID:24701812

  12. Tubular cellulose/starch gel composite as food enzyme storehouse.

    PubMed

    Barouni, Eleftheria; Petsi, Theano; Kanellaki, Maria; Bekatorou, Argyro; Koutinas, Athanasios

    2015-12-01

    The objective of this study was to produce a composite biocatalyst, based on porous cellulosic material, produced after wood sawdust delignification (tubular cellulose; TC) and starch gel (SG), for the development of bioprocesses related to enzyme applications. The composite biocatalyst was studied by Scanning Electron Microscopy to observe the SG deposition in the TC pores, and porosimetry analysis to determine the average pore diameter and surface area. The deposition of SG into the TC tubes provided a TC/SG composite with reduced pore sizes. X-ray powder diffractometry showed a decrease of crystallinity with increased SG ratio in the composite. The composite was used as an insoluble carrier for entrapment of the dairy enzyme rennin, leading to the production of an active biocatalyst for milk coagulation (initiation of milk clotting at about 20 min and full coagulation at about 200 min), creating perspectives for several applications in food enzyme research and technology. PMID:26041171

  13. A phase of liposomes with entangled tubular vesicles

    SciTech Connect

    Chiruvolu, S.; Naranjo, E.; Warriner, H.E.; Idziak, S.H.J.; Raedler, J.O.; Zasadzinski, J.A.; Safinya, C.R.; Plano, R.J.

    1994-11-18

    An equilibrium phase belonging to the family of bilayer liposomes in ternary mixtures of dimyristoylphosphatidylcholine (DMPC), water, and geraniol (a biological alcohol derived from oil-soluble vitamins that acts as a cosurfactant) has been identified. Electron and optical microscopy reveal the phase, labeled L{sub tv}, to be composed of highly entangled tubular vesicles. In situ x-ray diffraction confirms that the tubule walls are multilamellar with the lipids in the chain-melted state. Macroscopic observations show that the L{sub tv} phase coexists with the well-known L{sub 4} phase of spherical vesicles and a bulk L{sub {alpha}} phase. However, the defining characteristic of the L{sub tv} phase is the Weissenberg rod climbing effect under shear, which results from its polymer-like entangled microstructure. 26 refs., 5 figs.

  14. A Phase of Liposomes with Entangled Tubular Vesicles

    NASA Astrophysics Data System (ADS)

    Chiruvolu, Shivkumar; Warriner, Heidi E.; Naranjo, Edward; Idziak, Stefan H. J.; Radler, Joachim O.; Plano, Robert J.; Zasadzinski, Joseph A.; Safinya, Cyrus R.

    1994-11-01

    An equilibrium phase belonging to the family of bilayer liposomes in ternary mixtures of dimyristoylphosphatidylcholine (DMPC), water, and geraniol (a biological alcohol derived from oil-soluble vitamins that acts as a cosurfactant) has been identified. Electron and optical microscopy reveal the phase, labeled Ltv, to be composed of highly entangled tubular vesicles. In situ x-ray diffraction confirms that the tubule walls are multilamellar with the lipids in the chain-melted state. Macroscopic observations show that the Ltv phase coexists with the well-known L_4 phase of spherical vesicles and a bulk L_α phase. However, the defining characteristic of the Ltv phase is the Weissenberg rod climbing effect under shear, which results from its polymer-like entangled microstructure.

  15. Scalable Approach for Extrusion and Perfusion of Tubular, Heterotypic Biomaterials

    NASA Astrophysics Data System (ADS)

    Jeronimo, Mark David

    Soft material tubes are critical in the vasculature of mammalian tissues, forming networks of blood vessels and airways. Homogeneous and heterogeneous hydrogel tubes were extruded in a one-step process using a three layer microfluidic device. Co-axial cylindrical flow of crosslinking solutions and an alginate matrix is generated by a radial arrangement of microfluidic channels at the device's vertical extrusion outlet. The flow is confined and begins a sol-gel transition immediately as it extrudes at velocities upwards of 4 mm/s. This approach allows for predictive control over the dimensions of the rapidly formed tubular structures for outer diameters from 600 microm to 3 mm. A second microfluidic device hosts tube segments for controlled perfusion and pressurization using a reversible vacuum seal. On-chip tube deflection is observed and modeled as a measure of material compliance and circumferential elasticity. I anticipate applications of these devices for perfusion cell culture of cell-laden hydrogel tubes.

  16. Mass and heat transfer model of Tubular Solar Still

    SciTech Connect

    Ahsan, Amimul; Fukuhara, Teruyuki

    2010-07-15

    In this paper, a new mass and heat transfer model of a Tubular Solar Still (TSS) was proposed incorporating various mass and heat transfer coefficients taking account of the humid air properties inside the still. The heat balance of the humid air and the mass balance of the water vapor in the humid air were formulized for the first time. As a result, the proposed model enabled to calculate the diurnal variations of the temperature, water vapor density and relative humidity of the humid air, and to predict the hourly condensation flux besides the temperatures of the water, cover and trough, and the hourly evaporation flux. The validity of the proposed model was verified using the field experimental results carried out in Fukui, Japan and Muscat, Oman in 2008. The diurnal variations of the calculated temperatures and water vapor densities had a good agreement with the observed ones. Furthermore, the proposed model can predict the daily and hourly production flux precisely. (author)

  17. Novel Method Used to Inspect Curved and Tubular Structural Materials

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Baaklini, George Y.; Carney, Dorothy V.; Bodis, James R.; Rauser, Richard W.

    1999-01-01

    At the NASA Lewis Research Center, a technique for the ultrasonic characterization of plates has been extended to tubes and to curved structures in general. In this technique, one performs measurements that yield a thickness-independent value of the local through-the-thickness speed of sound in a specimen. From such measurements at numerous locations across the specimen, one can construct a map of velocity as a function of location. The gradients of velocity indicated by such a map indicate local through-the-thickness-averaged microstructural parameters that affect the speed of sound. Such parameters include the pore volume fraction, mass density, fiber volume fraction (in the case of a composite material), and chemical composition. Apparatus was designed to apply the technique to tubular and other curved specimens.

  18. Three-dimensional analysis of tubular permanent magnet machines

    NASA Astrophysics Data System (ADS)

    Chai, J.; Wang, J.; Howe, D.

    2006-04-01

    This paper presents results from a three-dimensional finite element analysis of a tubular permanent magnet machine, and quantifies the influence of the laminated modules from which the stator core is assembled on the flux linkage and thrust force capability as well as on the self- and mutual inductances. The three-dimensional finite element (FE) model accounts for the nonlinear, anisotropic magnetization characteristic of the laminated stator structure, and for the voids which exist between the laminated modules. Predicted results are compared with those deduced from an axisymmetric FE model. It is shown that the emf and thrust force deduced from the three-dimensional model are significantly lower than those which are predicted from an axisymmetric field analysis, primarily as a consequence of the teeth and yoke being more highly saturated due to the presence of the voids in the laminated stator core.

  19. Urinary Markers of Tubular Injury in HIV-Infected Patients

    PubMed Central

    Gebreweld, Angesom

    2016-01-01

    Renal disease is a common complication of HIV-infected patients, associated with increased risk of cardiovascular events, progression to AIDS, AIDS-defining illness, and mortality. Early and accurate identification of renal disease is therefore crucial to improve patient outcomes. The use of serum creatinine, along with proteinuria, to detect renal involvement is essentially to screen for markers of glomerular disease and may not be effective in detecting earlier stages of renal injury. Therefore, more sensitive and specific markers are needed in order to early identify HIV-infected patients at risk of renal disease. This review article summarizes some new and important urinary markers of tubular injury in HIV-infected patients and their clinical usefulness in the renal safety follow-up of TDF-treated patients. PMID:27493802

  20. Corrosion behavior of the expandable tubular in formation water

    NASA Astrophysics Data System (ADS)

    Gao, Shu-jun; Dong, Chao-fang; Fu, An-qing; Xiao, Kui; Li, Xiao-gang

    2015-02-01

    The corrosion behavior of expandable tubular materials was investigated in simulated downhole formation water environments using a series of electrochemical techniques. The corrosion morphologies in the real downhole environment after three months of application were also observed by stereology microscopy and scanning electron microscopy (SEM). The results show that, compared with the unexpanded sample, the area of ferrite increases dramatically after a 7.09% expansion. The expanded material shows a higher corrosion current in the polarization curve and a lower corrosion resistance in the electrochemical impedance spectroscopy (EIS) plot at every studied temperature. The determined critical pitting temperatures (CPT) before and after expansion are 87.5°C and 79.2°C, respectively. SEM observations demonstrate stress corrosion cracks, and CO2 corrosion and H2S corrosion also occur in the downhole environment. Due to additional defects generated during the plastic deformation, the corrosion performance of the expanded tubing deteriorates.

  1. Evaluation of composite flattened tubular specimen. [fatigue tests

    NASA Technical Reports Server (NTRS)

    Liber, T.; Daniel, I. M.

    1978-01-01

    Flattened tubular specimens of graphite/epoxy, S-glass/epoxy, Kevlar-49/epoxy, and graphite/S-glass/epoxy hybrid materials were evaluated under static and cyclic uniaxial tensile loading and compared directly with flat coupon data of the same materials generated under corresponding loading conditions. Additional development for the refinement of the flattened specimen configuration and fabrication was required. Statically tested graphite/epoxy, S-glass/epoxy, and Kevlar 49/epoxy flattened tube specimens exhibit somewhat higher average strengths than their corresponding flat coupons. Flattened tube specimens of the graphite/S-glass/epoxy hybrid and the graphite/epoxy flattened tube specimens failed in parasitic modes with consequential lower strength than the corresponding flat coupons. Fatigue tested flattened tube specimens failed in parasitic modes resulting in lower fatigue strengths than the corresponding flat coupons.

  2. On milling of thin-wall conical and tubular workpieces

    NASA Astrophysics Data System (ADS)

    Tsai, Mu-Ping; Tsai, Nan-Chyuan; Yeh, Cheng-Wei

    2016-05-01

    Thin-wall tubular-geometry workpieces have been widely applied in aircraft and medical industries. However, due to the special geometry of this kind of workpieces and induced poor machinability, the desired accuracy of machining tends to be greatly degraded, no matter what type of metal-cutting task such as milling, drilling or turning is undertaken. Though numerous research reports are available that the tool path can be planned on the basis of preset surface profile before actual milling operation is performed, it is still difficult to predict the real-time surface profile errors for peripheral milling of thin-wall tubular workpieces. Instead of relying on tool path planning, this research is focused on how to real-time formulate the appropriate applied cutting torque via feedback of spindle motor current. On the other hand, a few suitable cutting conditions which are able to prevent potential break/crack of thin-wall workpieces and enhance productivity but almost retain the same cutting quality is proposed in this research. To achieve this goal, estimated surface profile error on machined parts due to deflections caused by both tool and workpiece is studied at first. Traditionally, by adjusting cutting parameters such as feed rate or cut depth, the deflection of tool or workpiece can be expected not to exceed the specified limit. Instead, an effective feedback control loop is proposed by this work for applying real-time appropriate applied cutting torque to prevent potential break/crack of the thin-wall conical workpieces. The torque estimation approach by spindle motor current feedback and the corresponding fuzzy logic controller are employed. Compared with constant cutting torque during milling operation in tradition manner, it is observed that the time consumption of milling cycle by aid of the aforesaid fuzzy logic controller is greatly shortened while the resulted cutting accuracy upon finish of workpiece can be almost retained.

  3. Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications

    PubMed Central

    Hossain, Kazi M. Zakir; Zhu, Chenkai; Felfel, Reda M.; Sharmin, Nusrat; Ahmed, Ifty

    2015-01-01

    Tubular scaffolds with aligned polylactic acid (PLA) fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc) solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP) content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM) revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT) analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS) media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line) revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications. PMID:26184328

  4. Factors affecting plant growth in membrane nutrient delivery

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  5. Performance of anaerobic membrane bioreactor during digestion and thickening of aerobic membrane bioreactor excess sludge.

    PubMed

    Hafuka, Akira; Mimura, Kazuhisa; Ding, Qing; Yamamura, Hiroshi; Satoh, Hisashi; Watanabe, Yoshimasa

    2016-10-01

    In this study, we evaluated the performance of an anaerobic membrane bioreactor in terms of digestion and thickening of excess sludge from an aerobic membrane bioreactor. A digestion reactor equipped with an external polytetrafluoroethylene tubular microfiltration membrane module was operated in semi-batch mode. Solids were concentrated by repeated membrane filtration and sludge feeding, and their concentration reached 25,400mg/L after 92d. A high chemical oxygen demand (COD) removal efficiency, i.e., 98%, was achieved during operation. A hydraulic retention time of 34d and a pulse organic loading rate of 2200mg-COD/(L-reactor) gave a biogas production rate and biogas yield of 1.33L/(reactor d) and 0.08L/g-CODinput, respectively. The external membrane unit worked well without membrane cleaning for 90d. The transmembrane pressure reached 25kPa and the filtration flux decreased by 80% because of membrane fouling after operation for 90d. PMID:27394993

  6. Ceramic membranes for high temperature hydrogen separation

    SciTech Connect

    Adcock, K.D.; Fain, D.E.; James, D.L.; Powell, L.E.; Raj, T.; Roettger, G.E.; Sutton, T.G.

    1997-12-01

    The separative performance of the authors` ceramic membranes has been determined in the past using a permeance test system that measured flows of pure gases through a membrane at temperatures up to 275 C. From these data, the separation factor was determined for a particular gas pair from the ratio of the pure gas specific flows. An important project goal this year has been to build a Mixed Gas Separation System (MGSS) for measuring the separation efficiencies of membranes at higher temperatures and using mixed gases. The MGSS test system has been built, and initial operation has been achieved. The MGSS is capable of measuring the separation efficiency of membranes at temperatures up to 600 C and pressures up to 100 psi using a binary gas mixture such as hydrogen/methane. The mixed gas is fed into a tubular membrane at pressures up to 100 psi, and the membrane separates the feed gas mixture into a permeate stream and a raffinate stream. The test membrane is sealed in a stainless steel holder that is mounted in a split tube furnace to permit membrane separations to be evaluated at temperatures up to 600 C. The compositions of the three gas streams are measured by a gas chromatograph equipped with thermal conductivity detectors. The test system also measures the temperatures and pressures of all three gas streams as well as the flow rate of the feed stream. These data taken over a range of flows and pressures permit the separation efficiency to be determined as a function of the operating conditions. A mathematical model of the separation has been developed that permits the data to be reduced and the separation factor for the membrane to be determined.

  7. Evaluation of nephrotoxicity in vitro using a suspension of highly purified porcine proximal tubular cells and characterization of the cells in primary culture.

    PubMed

    Kruidering, M; Maasdam, D H; Prins, F A; de Heer, E; Mulder, G J; Nagelkerke, J F

    1994-01-01

    Proximal tubular cells (PTC) were isolated from porcine kidney by collagenase treatment, subsequently purified on a discontinuous density gradient and finally cultured. Porcine PTC (PPTC) in primary culture expressed keratin, characteristics of epithelia and brush border specific glycoproteins (FX1A). In addition, vimentin was present. All cells were negative for the endothelial marker pal-E. Less than 0.1% expressed the Tamm-Horsfall protein, characteristic of the distal tubule, while less than 0.3% of all cells in culture expressed desmin, characteristic of connective tissue (i.e. fibroblasts) and mesangial cells. Ultrastructural analysis revealed microvilli, tight junctions and abundant mitochondrial and lysosomes, all characteristics of proximal tubular cells. Freshly isolated PPTC were validated as in vitro model to detect nephrotoxicity by studying the effect of mercuric chloride, cis-platin, p-aminophenol and the halogenated alkenes 1,2 dichlorovinyl-l-cysteine, S-(1,1-difluoro-2,2-dichloroethyl)-L-cysteine (DCDFE-cys) and the glutathione conjugate of DCDFE on viability and mitochondrial membrane potential. The cells responded, time- and dose-dependently, to the nephrotoxic compounds with a decrease in mitochondrial membrane potential and loss of viability. The sensitivity of the porcine cells in detecting toxic effects corresponded favorably with in vitro systems derived from other animals. PMID:7859034

  8. 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.

  9. Intracellular calcium ions as regulators of renal tubular sodium transport.

    PubMed

    Windhager, E; Frindt, G; Yang, J M; Lee, C O

    1986-09-15

    This review addresses the putative role of intracellular calcium ions in the regulation of sodium transport by renal tubules. Cytoplasmic calcium-ion activities in proximal tubules of Necturus are less than 10(-7) M and can be increased by lowering the electrochemical potential gradient for sodium ions across the peritubular cell membrane, or by addition of quinidine or ionomycin to peritubular fluid. Whereas lowering of the peritubular Na concentration increases cytosolic [Ca++] and [H+], ionomycin, a calcium ionophore, raises intracellular [Ca++] without decreasing pHi. The intracellular calcium-ion level is maintained by transport processes in the plasma membrane and membranes of intracellular organelles, as well as by calcium-binding proteins. Calcium ions inhibit net transport of sodium by reducing the rate of sodium entry across the luminal cell membrane. In the collecting tubule this inhibition is caused, at least in part, by an indirect reduction in the activity of the amiloride-sensitive sodium channel. PMID:2430134

  10. Wrought lead-calcium-tin alloys for tubular lead/acid battery grids

    NASA Astrophysics Data System (ADS)

    Prengaman, R. David

    Lead/acid batteries with tubular grids for the positive electrodes give flatter discharge curves and higher cycle life than batteries using flat plates. Most tubular grids for motive-power batteries contain 9-11 wt.% antimony. Recently, alloys with 1-6 wt.% antimony have been used for reduced maintenance batteries. Sealed, valve-regulated batteries with tubular positive grids for motive power, telecommunications, and UPS service are produced from cast lead-calcium-tin alloys. While these alloys permit the construction of such batteries, cast PbCaSn alloys are significantly inferior to cast PbSb alloys in mechanical properties. Wrought PbCaSn alloys, when used for tubular grids, permit the application of maintenance-free alloys with mechanical properties comparable with, or higher than, those of high-antimony alloys. Wrought materials increase life due to the absence of casting defects. Wrought lead-calcium alloys also offer a dramatic improvement in creep and corrosion resistance compared with conventional cast, tubular, PbCaSn alloys, as well as superior conductivity to cast PbSb. Wrought PbCaSn alloys permit the production of tubular grids at high speed in shapes and forms that are difficult to produce from cast materials. These grid shapes can lead to higher performance, higher discharge-rate, tubular plates. This paper discusses the mechanical properties, grain structure, and corrosion behaviour of cast and wrought PbCaSn and PbSb alloys for tubular grids. It also suggests manufacturing techniques for high performance, wrought, tubular plates.

  11. Tubular Carcinoma of the Breast: A Single Institution's Experience of a Favorable Prognosis.

    PubMed

    Boyan, William; Shea, Brian; Farr, Michael; Kohli, Manpreet; Ginalis, Ernest

    2016-06-01

    Tubular carcinoma is a subtype of invasive breast cancer that comprises 1 to 4 per cent of invasive breast cancers. Prior studies show nearly 100 per cent 15 year survival rate for tubular carcinoma compared to the 89.2 per cent five year survival of all breast cancers. These encouraging statistics beg the question should tubular cancers be treated as other invasive cancers, or can some patients be spared an invasive procedure or the side effects of adjuvant therapy? Fifty-seven cases of tubular carcinoma over 16 years were analyzed. All relevant aspects of the patient's history, treatment, and outcomes were documented. The aim was compare treatment outcomes of tubular breast cancer outcomes to that of all invasive breast cancers. Of the 57 patients, local recurrence was seen in two patients (3.5%) only one of which recurred as a tubular carcinoma (1.75%). There were no cancer-related mortalities. A look into our institution's data supported the notion that tubular carcinoma of the breast is a less aggressive histological type. Of our 57 cases, only two recurrences (3.5%) were noted and there were no cancer-related mortalities. Interestingly only one patient (1.75%) recurred as tubular carcinoma. Without controlling for adjuvant therapy, recommendations cannot be made for a less aggressive treatment plan at this point. Future randomized controlled trials may lead to a less aggressive treatment plan for this favorable subtype. On the basis of this study and others like it, physicians can give evidenced-based favorable prognosis with a diagnosis of tubular carcinoma of the breast. PMID:27305881

  12. Porous membrane utilization in plant nutrient delivery

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  13. Hydrothermal growth of NiSe 2 tubular microcrystals assisted by PVA

    NASA Astrophysics Data System (ADS)

    Fan, Hai; Zhang, Maofeng; Zhang, Xianwen; Qian, Yitai

    2009-10-01

    NiSe 2 tubular microcrystals assembled of nanoparticles have been prepared via a hydrothermal method in an ethanolamine and water mixed solution assisted by polyvinyl alcohol (PVA). The prepared tubular crystals with hexagonal structure are composed of nanoparticles with average diameter of 30 nm. It was found that the phase of the products could be adjusted by the molar ratio of the reactants (Ni/Se), and the morphology of the products could be greatly influenced by the quantity of surfactant PVA. Based on the experimental results, the possible formation mechanism of NiSe 2 tubular microcrystals is also discussed.

  14. Closed membrane shapes with attached BAR domains subject to external force of actin filaments.

    PubMed

    Mesarec, Luka; Góźdź, Wojciech; Iglič, Veronika Kralj; Kralj, Samo; Iglič, Aleš

    2016-05-01

    Membrane deformations induced by attached BAR superfamily domains could trigger or facilitate the growth of plasma membrane protrusions. The BAR domain family consists of BAR, F-BAR and I-BAR domains, each enforcing a different local curvature when attached to the membrane surface. Our theoretical study mainly focuses on the role of I-BAR in the membrane tubular deformations generated or stabilised by actin filaments. The influence of the area density of membrane attached BAR domains and their intrinsic curvature on the closed membrane shapes (vesicles) was investigated numerically. We derived an analytical approximative expression for the critical relative area density of BARs at which the membrane tubular protrusions on vesicles are most prominent. We have shown that the BARs with a higher intrinsic curvature induce thinner and longer cylindrical protrusions. The average orientation of the membrane attached BARs is altered when the vesicle shape is subjected to external force of growing actin rod-like structure inside a vesicle. The average orientation angle of membrane attached BARs may indicate whether the actin filaments are just stabilising the protrusion or generating it by stretching the vesicle. PMID:26854580

  15. 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

  16. 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 ...

  17. Molecular Mechanism of Renal Tubular Secretion of the Antimalarial Drug Chloroquine ▿

    PubMed Central

    Müller, Fabian; König, Jörg; Glaeser, Hartmut; Schmidt, Ingrid; Zolk, Oliver; Fromm, Martin F.; Maas, Renke

    2011-01-01

    The antimalarial drug chloroquine is eliminated to a significant extent by renal tubular secretion. The molecular mechanism of renal chloroquine secretion remains unknown. We hypothesized that organic cation transporter 2 (OCT2) and multidrug and toxin extrusion protein 1 (MATE1), localized in the basolateral and luminal membranes of proximal tubule cells, respectively, are involved in chloroquine transport. The interaction of chloroquine with both transporters was investigated using single-transfected human embryonic kidney 293 (HEK293)-MATE1 cells in uptake experiments and single-transfected Madin-Darby canine kidney II (MDCK)-OCT2 and MDCK-MATE1 cells as well as double-transfected MDCK-OCT2-MATE1 cells grown as polarized monolayers on transwell filters. In HEK293-MATE1 cells, chloroquine competitively inhibited MATE1-mediated metformin uptake (Ki = 2.8 μM). Cellular accumulation of chloroquine was significantly lower (P < 0.001) and transcellular chloroquine transport was significantly increased (P < 0.001) in MDCK-MATE1 and MDCK-OCT2-MATE1 cells compared to vector control cells after basal addition of chloroquine (0.1 to 10 μM). In contrast, no difference in cellular accumulation or transcellular transport of chloroquine was observed between MDCK-OCT2 and vector control cells. In line with an oppositely directed proton gradient acting as a driving force for MATE1, basal-to-apical transport of chloroquine by MDCK-OCT2-MATE1 cells increased with decreasing apical pH from 7.8 to 6.0. Transcellular transport of chloroquine by MDCK-OCT2-MATE1 cells was inhibited by cimetidine, trimethoprim, and amitriptyline. Our data demonstrate that chloroquine is a substrate and potent competitive inhibitor of MATE1, whereas OCT2 seems to play no role in chloroquine uptake. Concomitantly administered MATE1 inhibitors are likely to modify the renal secretion of chloroquine. PMID:21518836

  18. Investigation of tubular handling of bicarbonate in man. A new approach utilizing stable carbon isotope fractionation.

    PubMed Central

    Burbea, Z H; Luz, B; Lazar, B; Winaver, J; Better, O S

    1983-01-01

    Two alternative mechanisms have been proposed for tubular reabsorption of bicarbonate: (a) H+ secretion and CO2 reabsorption and (b) direct reabsorption of HCO-3. In an attempt to differentiate between the two mechanisms, the present study utilized the natural abundance of stable carbon isotopes (13C, 12C) in the urinary total CO2. This novel methodology used mass spectrometric analysis of 13C/12C ratios in urinary total CO2 under normal conditions and during acetazolamide treatment. Blood and respiratory CO2 were analyzed to yield reference values. The results demonstrate that alkaline urine is preferentially enriched with 13C relative to the blood. It is suggested that this fractionation results from reaction out of isotopic equilibrium in which HCO-3 converts to CO2 during the reabsorption process in the distal nephron. The presence of carbonic anhydrase in the proximal nephron results in rapid isotopic exchange between CO2 and HCO-3 and keeps them in isotopic equilibrium. The ratio of urinary 13C/12C increases strikingly after acetazolamide administration and consequent inhibition of carbonic anhydrase in the proximal tubule. Although it is possible that in the latter case high HCO-3 generates the CO2 (ampholyte effect), the isotope fractionation indicates that CO2 rather than HCO-3 is reabsorbed. In contrast, at low urinary pH and total CO2 values, the carbon isotope composition approaches that of blood CO2. This indicates rapid CO2 exchange between urine and blood, through luminal membrane highly permeable to CO2. These results could be anticipated by a mathematical model constructed to plot 13C concentration of urinary total CO2. It is concluded that the mechanism of HCO-3 reclamation in man (and, by inference, in other mammals as well) works by conversion of HCO-3 to CO2 and reabsorption of CO2. PMID:6417168

  19. Structure of assemblies of metal nanowires in mesoporous alumina membranes studied by EXAFS, XANES, X-ray diffraction and SAXS.

    PubMed

    Benfield, Robert E; Grandjean, Didier; Dore, John C; Esfahanian, Hamid; Wu, Zhonghua; Kröll, Michael; Geerkens, Marcus; Schmid, Günter

    2004-01-01

    Mesoporous alumina membranes ("anodic aluminium oxide", or "AAO") are made by anodic oxidation of aluminium metal. These membranes contain hexagonal arrays of parallel non-intersecting cylindrical pores perpendicular to the membrane surface. By varying the anodisation voltage, the pore diameters are controllable within the range 5-250 nm. We have used AAO membranes as templates for the electrochemical deposition of metals within the pores to produce nanowires. These represent assemblies of one-dimensional quantum wires with prospective applications in electronic, optoelectronic and magnetic devices. Detailed characterisation of the structures of these nanowire assemblies on a variety of length scales is essential to understand their physical properties and evaluate their possible applications. We have used EXAFS, XANES, WAXS, high energy X-ray diffraction and SAXS to study their structure and bonding. In this paper we report the results of our studies of four different nanowire systems supported in AAO membranes. These are the ferromagnetic metals iron and cobalt, the superconducting metal tin, and the semiconductor gallium nitride. Iron nanowires in pores of diameter over the range 12 nm-72 nm are structurally very similar to bcc bulk iron. They have a strong preferred orientation within the alumina pores. Their XANES shows significant differences from that of bulk iron, showing that the electronic structure of the iron nanowires depends systematically on their diameter. Cobalt nanowires are composed of a mixture of hcp and fcc phases, but the ratio of the two phases does not depend in a simple way on the pore diameter or preparation conditions. In bulk cobalt, the fcc beta-phase is normally stable only at high temperatures. Strong preferred orientation of the c-axis in the pores was found. Tin nanowires in alumina membranes with pores diameters between 12 nm and 72 nm have a tetragonal beta-structure at ambient temperature and also at 80 K. Magnetic

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

    NASA Technical Reports Server (NTRS)

    Richter, R.

    1982-01-01

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

  1. Poxviruses Encode a Reticulon-Like Protein that Promotes Membrane Curvature

    PubMed Central

    Erlandson, Karl J.; Bisht, Himani; Weisberg, Andrea S.; Hyun, Seong-In; Hansen, Bryan T.; Fischer, Elizabeth R.; Hinshaw, Jenny E.; Moss, Bernard

    2016-01-01

    Poxviruses are enveloped DNA viruses that replicate within the cytoplasm. The first viral structures are crescents and spherical particles with a lipoprotein membrane bilayer thought to be derived from the endoplasmic reticulum (ER). We determined that A17, a conserved viral transmembrane protein essential for crescent formation, forms homo-oligomers and shares topological features with cellular reticulon-like proteins, which promote membrane curvature and contribute to the tubular structure of the ER. When the purified A17 protein was incorporated into liposomes, 25 nm diameter vesicles and tubules formed at low and high A17 concentrations, respectively. In addition, intracellular expression of A17, in the absence of other viral structural proteins, transformed the ER into aggregated 3-dimensional tubular networks. We suggest that A17 is a viral reticulon-like protein that contributes to curvature during biogenesis of the poxvirus membrane. PMID:26923595

  2. Membrane-Based Energy Efficient Dewatering of Microalgae in Biofuels Production and Recovery of Value Added Co-Products

    SciTech Connect

    Bhave, Ramesh R; Kuritz, Tanya; Powell, Lawrence E; Adcock, Kenneth Dale

    2012-01-01

    The objective of this paper is to describe the use of membranes for energy efficient biomass harvesting and dewatering. We have evaluated the dewatering of Nannochloropsis sp. with polymeric hollow fiber and tubular inorganic membranes to demonstrate the capabilities of a membrane-based system to achieve microalgal biomass of >150 g/L (dry wt.) and ~99% volume reduction through dewatering. The particle free filtrate containing the growth media is suitable for recycle and reuse. For cost-effective processing, hollow fiber membranes can be utilized to recover 90-95% media for recycle. Tubular membranes can provide additional media and water recovery to achieve target final concentrations. Based on the operating conditions used in this study and taking into scale-up considerations, it can be shown that an integrated hollow fiber-tubular membrane system can process microalgal biomass with at least 80% lower energy requirement compared to traditional processes. Backpulsing was found to be an effective flux maintenance strategy to minimize flux decline at high biomass concentration. An effective chemical cleaning protocol was developed for regeneration of fouled membranes.

  3. Membrane-based energy efficient dewatering of microalgae in biofuels production and recovery of value added co-products.

    PubMed

    Bhave, Ramesh; Kuritz, Tanya; Powell, Lawrence; Adcock, Dale

    2012-05-15

    The objective of this paper is to describe the use of membranes for energy efficient biomass harvesting and dewatering. The dewatering of Nannochloropsis sp. was evaluated with polymeric hollow fiber and tubular inorganic membranes to demonstrate the capabilities of a membrane-based system to achieve microalgal biomass of >150 g/L (dry wt.) and ∼99% volume reduction through dewatering. The particle free filtrate containing the growth media is suitable for recycle and reuse. For cost-effective processing, hollow fiber membranes can be utilized to recover 90-95% media for recycle. Tubular membranes can provide additional media and water recovery to achieve target final concentrations. Based on the operating conditions used in this study and taking into scale-up considerations, an integrated hollow fiber-tubular membrane system can process microalgal biomass with at least 80% lower energy requirement compared to traditional processes. Backpulsing was found to be an effective flux maintenance strategy to minimize flux decline at high biomass concentration. An effective chemical cleaning protocol was developed for regeneration of fouled membranes. PMID:22510094

  4. Neuropilin-1 and neuropilin-2 are differentially expressed in human proteinuric nephropathies and cytokine-stimulated proximal tubular cells.

    PubMed

    Schramek, Herbert; Sarközi, Rita; Lauterberg, Christina; Kronbichler, Andreas; Pirklbauer, Markus; Albrecht, Rudolf; Noppert, Susie-Jane; Perco, Paul; Rudnicki, Michael; Strutz, Frank M; Mayer, Gert

    2009-11-01

    Neuropilin-1 (NRP1) and neuropilin-2 (NRP2) are transmembrane glycoproteins with large extracellular domains that interact with class 3 semaphorins, vascular endothelial growth factor (VEGF) family members, and ligands, such as hepatocyte growth factor, platelet-derived growth factor BB, transforming growth factor-beta1 (TGF-beta1), and fibroblast growth factor2 (FGF2). Neuropilins (NRPs) have been implicated in tumor growth and vascularization, as novel mediators of the primary immune response and in regeneration and repair; however, their role in renal pathophysiology is largely unknown. Here, we report upregulation of tubular and interstitial NRP2 protein expression in patients with focal segmental glomerulosclerosis (FSGS). In an additional cohort of patients with minimal change disease (MCD), membranous nephropathy (MN), and FSGS, elevated NRP2 mRNA expression in kidney biopsies inversely correlated with estimated glomerular filtration rate (eGFR) at the time of biopsy. Furthermore, upregulation of NRP2 mRNA correlated with post-bioptic decline of kidney function. Expression of NRP1 and NRP2 in human proximal tubular cells (PTCs) was differentially affected after stimulation with TGF-beta1, interleukin-1beta (IL-1beta), and oncostatin M (OSM). Although the pro-fibrotic mediators, TGF-beta1 and IL-1beta, induced upregulation of NRP2 expression but downregulation of NRP1 expression, OSM stimulated the expression of both NRP1 and NRP2. Basal and OSM-induced NRP1 mRNA expression, as well as TGF-beta1-induced NRP2 mRNA and protein expression were partially mediated by MEK1/2-ERK1/2 signaling. This is the first report suggesting a differential role of NRP1 and NRP2 in renal fibrogenesis, and TGF-beta1, IL-1beta, and OSM represent the first ligands known to stimulate NRP2 expression in mammalian cells. PMID:19736548

  5. Alpha-tubulin enhanced renal tubular cell proliferation and tissue repair but reduced cell death and cell-crystal adhesion.

    PubMed

    Manissorn, Juthatip; Khamchun, Supaporn; Vinaiphat, Arada; Thongboonkerd, Visith

    2016-01-01

    Adhesion of calcium oxalate (CaOx) crystals on renal tubular epithelial cells is a critical event for kidney stone disease that triggers many cascades of cellular response. Our previous expression proteomics study identified several altered proteins in MDCK renal tubular cells induced by CaOx crystals. However, functional significance of those changes had not been investigated. The present study thus aimed to define functional roles of such proteome data. Global protein network analysis using STRING software revealed α-tubulin, which was decreased, as one of central nodes of protein-protein interactions. Overexpression of α-tubulin (pcDNA6.2-TUBA1A) was then performed and its efficacy was confirmed. pcDNA6.2-TUBA1A could maintain levels of α-tubulin and its direct interacting partner, vimentin, after crystal exposure. Also, pcDNA6.2-TUBA1A successfully reduced cell death to almost the basal level and increased cell proliferation after crystal exposure. Additionally, tissue repair capacity was improved in pcDNA6.2-TUBA1A cells. Moreover, cell-crystal adhesion was reduced by pcDNA6.2-TUBA1A. Finally, levels of potential crystal receptors (HSP90, HSP70, and α-enolase) on apical membrane were dramatically reduced to basal levels by pcDNA6.2-TUBA1A. These findings implicate that α-tubulin has protective roles in kidney stone disease by preventing cell death and cell-crystal adhesion, but on the other hand, enhancing cell proliferation and tissue repair function. PMID:27363348

  6. Alpha-tubulin enhanced renal tubular cell proliferation and tissue repair but reduced cell death and cell-crystal adhesion

    PubMed Central

    Manissorn, Juthatip; Khamchun, Supaporn; Vinaiphat, Arada; Thongboonkerd, Visith

    2016-01-01

    Adhesion of calcium oxalate (CaOx) crystals on renal tubular epithelial cells is a critical event for kidney stone disease that triggers many cascades of cellular response. Our previous expression proteomics study identified several altered proteins in MDCK renal tubular cells induced by CaOx crystals. However, functional significance of those changes had not been investigated. The present study thus aimed to define functional roles of such proteome data. Global protein network analysis using STRING software revealed α-tubulin, which was decreased, as one of central nodes of protein-protein interactions. Overexpression of α-tubulin (pcDNA6.2-TUBA1A) was then performed and its efficacy was confirmed. pcDNA6.2-TUBA1A could maintain levels of α-tubulin and its direct interacting partner, vimentin, after crystal exposure. Also, pcDNA6.2-TUBA1A successfully reduced cell death to almost the basal level and increased cell proliferation after crystal exposure. Additionally, tissue repair capacity was improved in pcDNA6.2-TUBA1A cells. Moreover, cell-crystal adhesion was reduced by pcDNA6.2-TUBA1A. Finally, levels of potential crystal receptors (HSP90, HSP70, and α-enolase) on apical membrane were dramatically reduced to basal levels by pcDNA6.2-TUBA1A. These findings implicate that α-tubulin has protective roles in kidney stone disease by preventing cell death and cell-crystal adhesion, but on the other hand, enhancing cell proliferation and tissue repair function. PMID:27363348

  7. Membrane invagination induced by Shiga toxin B-subunit: from molecular structure to tube formation.

    PubMed

    Pezeshkian, W; Hansen, A G; Johannes, L; Khandelia, H; Shillcock, J C; Kumar, P B S; Ipsen, J H

    2016-06-21

    The bacterial Shiga toxin is composed of an enzymatically active A-subunit, and a receptor-binding homopentameric B-subunit (STxB) that mediates intracellular toxin trafficking. Upon STxB-mediated binding to the glycolipid globotriaosylceramide (Gb3) at the plasma membrane of target cells, Shiga toxin is internalized by clathrin-dependent and independent endocytosis. The formation of tubular membrane invaginations is an essential step in the clathrin-independent STxB uptake process. However, the mechanism by which STxB induces these invaginations has remained unclear. Using a combination of all-atom molecular dynamics and Monte Carlo simulations we show that the molecular architecture of STxB enables the following sequence of events: the Gb3 binding sites on STxB are arranged such that tight avidity-based binding results in a small increment of local curvature. Membrane-mediated clustering of several toxin molecules then creates a tubular membrane invagination that drives toxin entry into the cell. This mechanism requires: (1) a precise molecular architecture of the STxB binding sites; (2) a fluid bilayer in order for the tubular invagination to form. Although, STxB binding to the membrane requires specific interactions with Gb3 lipids, our study points to a generic molecular design principle for clathrin-independent endocytosis of nanoparticles. PMID:27070906

  8. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT - REMOVAL OF PRECURSORS TO DISINFECTION BY-PRODUCTS IN DRINKING WATER, PCI MEMBRANE SYSTEMS FYNE PROCESS MODEL ROP 1434 WITH AFC-30 NANOFILTRATON AT BARROW, AK - NSF 00/19/EPADW395

    EPA Science Inventory

    Equipment testing and verification of PCI Membrane Systems Inc. Fyne Process nanofiltraton systems Model ROP 1434 equipped with a C10 module containing AFC-30 tubular membranes was conducted from 3/16-5/11/2000 in Barrow, AS. The source water was a moderate alkalinity, moderately...

  9. Automatic centerline extraction of irregular tubular structures using probability volumes from multiphoton imaging.

    PubMed

    Santamaría-Pang, A; Colbert, C M; Saggau, P; Kakadiaris, I A

    2007-01-01

    In this paper, we present a general framework for extracting 3D centerlines from volumetric datasets. Unlike the majority of previous approaches, we do not require a prior segmentation of the volume nor we do assume any particular tubular shape. Centerline extraction is performed using a morphology-guided level set model. Our approach consists of: i) learning the structural patterns of a tubular-like object, and ii) estimating the centerline of a tubular object as the path with minimal cost with respect to outward flux in gray level images. Such shortest path is found by solving the Eikonal equation. We compare the performance of our method with existing approaches in synthetic, CT, and multiphoton 3D images, obtaining substantial improvements, especially in the case of irregular tubular objects. PMID:18044604

  10. Inhibition of renal membrane binding and nephrotoxicity of aminoglycosides

    SciTech Connect

    Williams, P.D.; Hottendorf, G.H.; Bennett, D.B.

    1986-06-01

    The initial event in the renal tubular reabsorption of nephrotoxic aminoglycosides involves binding to brush border membranes. This primary event was measured in renal brush border membrane vesicles prepared from rat renal cortex utilizing (3H)gentamicin. In order to gain structure-activity information regarding this interaction the effect of substances having chemical similarities to aminoglycosides (sugars, polyamines and amino acids) on gentamicin binding to brush border membranes was determined. Polyamino acids were found to possess the greatest inhibitory potency. In addition to polymers of cationic amino acids (lysine, ornithine, arginine and histidine), polymers of neutral (asparagine) and acidic (aspartic and glutamic acid) amino acids also exhibited inhibition of the membrane binding of gentamicin. Inasmuch as inhibition of renal membrane binding has the potential to decrease aminoglycoside nephrotoxicity, several polyamino acids that inhibited membrane binding were tested in vivo for potential protective activity vs. gentamicin- and amikacin-induced nephrotoxicity. Polyasparagine90 and polyaspartic acid100 inhibited gentamicin and amikacin nephrotoxicity completely when coadministered to rats with the aminoglycosides. Polylysine20 provided complete and partial inhibition of gentamicin and amikacin nephrotoxicity, respectively. Whereas in vivo distribution studies revealed that cortical levels of (3H)amikacin were elevated slightly by the coadministration of polyaspartic acid, brush border and basolateral membranes contained significantly lower levels of the aminoglycoside (46 and 41% inhibition, respectively). These results question the role of charge per se in the binding of aminoglycosides to renal membranes and further confirm the importance of membrane binding in the pathogenesis of aminoglycoside nephrotoxicity.

  11. Oxygen-permeable ceramic membranes for gas separation

    SciTech Connect

    Balachandran, U.; Ma, B.; Maiya, P.S.; Dusek, J.T.; Mieville, R.L.; Picciolo, J.J.

    1998-02-01

    Mixed-conducting oxides have a wide range of applications, including fuel cells, gas separation systems, sensors, and electrocatalytic equipment. Dense ceramic membranes made of mixed-conducting oxides are particularly attractive for gas separation and methane conversion processes. Membranes made of Sr-Fe-Co oxide, which exhibits high combined electronic and oxygen ionic conductivities, can be used to selectively transport oxygen during the partial oxidation of methane to synthesis gas (syngas, i.e., CO + H{sub 2}). The authors have fabricated tubular Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes and tested them (some for more than 1,000 h) in a methane conversion reactor that was operating at 850--950 C. An oxygen permeation flux of {approx} 10 scc/cm{sup 2} {center_dot} min was obtained at 900 C in a tubular membrane with a wall thickness of 0.75 mm. Using a gas-tight electrochemical cell, the authors have also measured the steady-state oxygen permeability of flat Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes as a function of temperature and oxygen partial pressure(pO{sub 2}). Steady-state oxygen permeability increases with increasing temperature and with the difference in pO{sub 2} on the two sides of the membrane. At 900 C, an oxygen permeability of {approx} 2.5 scc/cm{sup 2} {center_dot} min was obtained in a 2.9-mm-thick membrane. This value agrees with that obtained in methane conversion reactor experiments. Current-voltage (I-V) characteristics determined in the gas-tight cell indicate that bulk effect, rather than surface exchange effect, is the main limiting factor for oxygen permeation of {approx} 1-mm-thick Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes at elevated temperatures (> 650 C).

  12. A reduced graphene oxide nanofiltration membrane intercalated by well-dispersed carbon nanotubes for drinking water purification.

    PubMed

    Chen, Xianfu; Qiu, Minghui; Ding, Hao; Fu, Kaiyun; Fan, Yiqun

    2016-03-14

    In this study, we report a promising rGO-CNT hybrid nanofiltration (NF) membrane that was fabricated by loading reduced graphene oxide that was intercalated with carbon nanotubes (rGO-CNTs) onto an anodic aluminum oxide (AAO) microfiltration membrane via a facile vacuum-assisted filtration process. To create this NF membrane, the CNTs were first dispersed using block copolymers (BCPs); the effects of the types and contents of BCPs used on the dispersion of CNTs have been investigated. The as-prepared rGO-CNT hybrid NF membranes were then used for drinking water purification to retain the nanoparticles, dyes, proteins, organophosphates, sugars, and particularly humic acid. Experimentally, it is shown that the rGO-CNT hybrid NF membranes have high retention efficiency, good permeability and good anti-fouling properties. The retention was above 97.3% even for methyl orange (327 Da); for other objects, the retention was above 99%. The membrane's permeability was found to be as high as 20-30 L m(-2) h(-1) bar(-1). Based on these results, we can conclude that (i) the use of BCPs as a surfactant can enhance steric repulsion and thus disperse CNTs effectively; (ii) placing well-dispersed 1D CNTs within 2D graphene sheets allows an uniform network to form, which can provide many mass transfer channels through the continuous 3D nanostructure, resulting in the high permeability and separation performance of the rGO-CNT hybrid NF membranes. PMID:26898192

  13. Bidirectional signalling between EphA2 and ephrinA1 increases tubular cell attachment, laminin secretion and modulates erythropoietin expression after renal hypoxic injury.

    PubMed

    Rodriguez, Stéphane; Rudloff, Stefan; Koenig, Katrin Franziska; Karthik, Swapna; Hoogewijs, David; Huynh-Do, Uyen

    2016-08-01

    Acute kidney injury (AKI) is common in hospitalized patients and has a poor prognosis, the severity of AKI being linked to progression to chronic kidney disease. This stresses the need to search for protective mechanisms during the acute phase. We investigated kidney repair after hypoxic injury using a rat model of renal artery branch ligation, which led to an oxygen gradient vertical to the corticomedullary axis. Three distinct zones were observed: tubular necrosis, infarction border zone and preserved normal tissue. EphA2 is a receptor tyrosine kinase with pivotal roles in cell architecture, migration and survival, upon juxtacrine contact with its membrane-bound ligand EphrinA1. Following hypoxia, EphA2 was up-regulated in cortical and medullary tubular cells, while EphrinA1 was up-regulated in interstitial cells adjacent to peritubular capillaries. Moreover, erythropoietin (EPO) messenger RNA (mRNA) was strongly expressed in the border zone of infarcted kidney within the first 6 h. To gain more insight into the biological impact of EphA2 and EphrinA1 up-regulation, we activated the signalling pathways in vitro using recombinant EphrinA1/Fc or EphA2/Fc proteins. Stimulation of EphA2 forward signalling in the proximal tubular cell line HK2 increased cell attachment and laminin secretion at the baso-lateral side. Conversely, activation of reverse signalling through EphrinA1 expressed by Hep3B cells promoted EPO production at both the transcriptional and protein level. Strikingly, in co-culture experiments, juxtacrine contact between EphA2 expressing MDCK and EphrinA1 expressing Hep3B was sufficient to induce a significant up-regulation of EPO mRNA production in the latter cells, even in the absence of hypoxic conditions. The synergistic effects of EphA2 and hypoxia led to a 15-20-fold increase of EPO expression. Collectively, our results suggest an important role of EphA2/EphrinA1 signalling in kidney repair after hypoxic injury through stimulation of (i) tubular

  14. Reducing the Manufacturing Cost of Tubular SOFC Technology

    SciTech Connect

    George, R.A.; Bessette, N.F.

    1997-12-31

    In recent years, Westinghouse Electric Corporation has made great strides in advancing tubular solid oxide fuel cell (SOFC) technology towards commercialization by the year 2001. In 1993, Westinghouse initiated a program to develop a `MWe Class` (1-3 MWe) pressurized SOFC (PSOFC) gas turbine (GT) combined cycle power system for distributed power applications because of its: (1) ultra high efficiency (approx. 63% net AC/LHV CH{sub 4}), (2) its compatibility with a factory packaged, minimum site work philosophy, and (3) its cost effectiveness. Since then two cost studies on this market entry product performed by consultants to the U.S. Department of Energy have confirmed Westinghouse cost studies that fully installed costs of under $1300/kWe can be achieved in the early commercialization years for such small PSOFC/GT power systems. The paper will present the results of these cost studies in the areas of cell manufacturing cost, PSOFC generator manufacturing cost, balance-of-plant (BOP) cost, and system installation cost. In addition, cost of electricity calculations will be presented.

  15. Tracheal stent prediction using statistical deformable models of tubular shapes

    NASA Astrophysics Data System (ADS)

    Pinho, R.; Huysmans, T.; Vos, W.; Sijbers, J.

    2008-03-01

    Tracheal stenosis is a narrowing of the trachea that impedes normal breathing. Tracheotomy is one solution, but subjects patients to intubation. An alternative technique employs tracheal stents, which are tubular structures that push the walls of the stenotic areas to their original location. They are implanted with endoscopes, therefore reducing the surgical risk to the patient. Stents can also be used in tracheal reconstruction to aid the recovery of reconstructed areas. Correct preoperative stent length and diameter specification is crucial to successful treatment, otherwise stents might not cover the stenotic area nor push the walls as required. The level of stenosis is usually measured from inside the trachea, either with endoscopes or with image processing techniques that, eg compute the distance from the centre line to the walls of the trachea. These methods are not suited for the prediction of stent sizes because they can not trivially estimate the healthy calibre of the trachea at the stenotic region. We propose an automatic method that enables the estimation of stent dimensions with statistical shape models of the trachea. An average trachea obtained from a training set of CT scans of healthy tracheas is placed in a CT image of a diseased person. The shape deforms according to the statistical model to match the walls of the trachea, except at stenotic areas. Since the deformed shape gives an estimation of the healthy trachea, it is possible to predict the size and diameter of the stent to be implanted in that specific subject.

  16. Twisted and tubular silica structures by anionic surfactant fibers encapsulation.

    PubMed

    Chekini, Mahshid; Guénée, Laure; Marchionni, Valentina; Sharma, Manish; Bürgi, Thomas

    2016-09-01

    Organic molecules imprinting can be used for introducing specific properties and functionalities such as chirality to mesoporous materials. Particularly organic self-assemblies can work as a scaffold for templating inorganic materials such as silica. During recent years chiral imprinting of anionic surfactant for fabrication of twisted rod-like silica structures assisted by co-structuring directing agent were thoroughly investigated. The organic self-assemblies of anionic surfactants can also be used for introducing other shapes in rod-like silica structures. Here we report the formation of amphiphilic N-miristoyl-l-alanine self-assemblies in aqueous solution upon stirring and at presence of l-arginine. These anionic surfactant self-assemblies form fibers that grow by increasing the stirring duration. The fibers were studied using transmission electron microscopy, infra-red spectroscopy and vibrational circular dichroism. Addition of silica precursor 1,2-bis(triethoxysilyl)ethylene and co-structuring directing agent N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride at different stages of fibers' growth leads to formation of different silica structures. By controlling stirring duration, we obtained twisted tubular silica structures as a result of fibers encapsulation. We decorated these structures with gold nanoparticles by different methods and measured their optical activity. PMID:27267039

  17. Steady State Response Analysis of a Tubular Piezoelectric Print Head.

    PubMed

    Chang, Jiaqing; Liu, Yaxin; Huang, Bo

    2016-01-01

    In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which can be classified as a plane strain problem because the radii of the tubes are considerably smaller than the lengths, is discussed in this paper. The geometric structure and the boundary conditions are all axisymmetric, so a one-dimensional mathematical model is constructed. By solving the model, the deformation field and stress field, as well as the electric potential distribution of the piezoelectric tube and glass tube, are obtained. The results show that the deformations are on the nanometer scale, the hoop stress is larger than the radial stress on the whole, and the potential is not linearly distributed along the radial direction. An experiment is designed to validate these computations. A discussion of the effect of the tubes' thicknesses on the system deformation status is provided. PMID:26771612

  18. Load tests on tubular piles in Coralline Strata

    SciTech Connect

    Gilchrist, J.M.

    1985-05-01

    At a coral reef site on the Red Sea coast of Saudi Arabia, load tests were performed on 1,422 mm diam tubular steel piles to verify pile design compression and tension capacities predicted by calculations. Although two tests were planned at separate site locations, five were performed (two on test pile A, and three on test pile B) due to the test results disproving some of the calculation assumptions. Test pile A was installed open-ended and the test results concluded: For a coring pile, the measured compression capacitites had reasonable agreement with those calculated (calculated overestimates = 5.2% and 16.3%); and the design assumption that a soil plug would form was disproved. Test pile B was installed with a structural plug fitted to the leading end and the test results concluded that the measured skin friction at 11 m penetration = zero; and the unit end bearing capacity assumed in the calculations was considerably larger than that measured in the tests at 11 m and 30 m penetration (calculated overestimates = 181% and 164%).

  19. Distal renal tubular acidosis with multiorgan autoimmunity: a case report.

    PubMed

    van den Wildenberg, Maria J; Hoorn, Ewout J; Mohebbi, Nilufar; Wagner, Carsten A; Woittiez, Arend-Jan; de Vries, Peter A M; Laverman, Gozewijn D

    2015-04-01

    A 61-year-old woman with a history of pernicious anemia presented with progressive muscle weakness and dysarthria. Hypokalemic paralysis (serum potassium, 1.4 mEq/L) due to distal renal tubular acidosis (dRTA) was diagnosed. After excluding several possible causes, dRTA was considered autoimmune. However, the patient did not meet criteria for any of the autoimmune disorders classically associated with dRTA. She had very high antibody titers against parietal cells, intrinsic factor, and thyroid peroxidase (despite normal thyroid function). The patient consented to a kidney biopsy, and acid-base transporters, anion exchanger type 1 (AE1), and pendrin were undetectable by immunofluorescence. Indirect immunofluorescence detected diminished abundance of AE1- and pendrin-expressing intercalated cells in the kidney, as well as staining by the patient's serum of normal human intercalated cells and parietal cells expressing the adenosine triphosphatase hydrogen/potassium pump (H(+)/K(+)-ATPase) in normal human gastric mucosa. The dRTA likely is caused by circulating autoantibodies against intercalated cells, with possible cross-reactivity against structures containing gastric H(+)/K(+)-ATPase. This case demonstrates that in patients with dRTA without a classic autoimmune disorder, autoimmunity may still be the underlying cause. The mechanisms involved in autoantibody development and how dRTA can be caused by highly specific autoantibodies against intercalated cells have yet to be determined. PMID:25533600

  20. Direct-write diffracting tubular optical components using femtosecond lasers

    NASA Astrophysics Data System (ADS)

    McMillen, Ben; Bellouard, Yves

    2014-03-01

    Over the last decade, femtosecond lasers have been used extensively for the fabrication of optical elements via direct writing and in combination with chemical etching. These processes have been an enabling technology for manufacturing a variety of devices such as waveguides, fluidic channels, and mechanical components. Here, we present high quality micro-scale optical components buried inside various glass substrates such as soda-lime glass or fused silica. These components consist of high-precision, simple patterns with tubular shapes. Typical diameters range from a few microns to one hundred microns. With the aid of high-bandwidth, high acceleration flexure stages, we achieve highly symmetric pattern geometries, which are particularly important for achieving homogeneous stress distribution within the substrate. We model the optical properties of these structures using beam propagation simulation techniques and experimentally demonstrate that such components can be used as cost-effective, low-numerical aperture lenses. Additionally, we investigate their capability for studying the stress-distribution induced by the laser-affected zones and possible related densification effects.

  1. HIGH-TEMPERATURE TUBULAR SOLID OXIDE FUEL CELL GENERATOR DEVELOPMENT

    SciTech Connect

    S.E. Veyo

    1998-09-01

    During the Westinghouse/USDOE Cooperative Agreement period of November 1, 1990 through November 30, 1997, the Westinghouse solid oxide fuel cell has evolved from a 16 mm diameter, 50 cm length cell with a peak power of 1.27 watts/cm to the 22 mm diameter, 150 cm length dimensions of today's commercial prototype cell with a peak power of 1.40 watts/cm. Accompanying the increase in size and power density was the elimination of an expensive EVD step in the manufacturing process. Demonstrated performance of Westinghouse's tubular SOFC includes a lifetime cell test which ran for a period in excess of 69,000 hours, and a fully integrated 25 kWe-class system field test which operated for over 13,000 hours at 90% availability with less than 2% performance degradation over the entire period. Concluding the agreement period, a 100 kW SOFC system successfully passed its factory acceptance test in October 1997 and was delivered in November to its demonstration site in Westervoort, The Netherlands.

  2. Metachronous tubulovillous and tubular adenomas of the anal canal.

    PubMed

    Nozawa, Hiroaki; Ishihara, Soichiro; Morikawa, Teppei; Tanaka, Junichiro; Yasuda, Koji; Ohtani, Kensuke; Nishikawa, Takeshi; Tanaka, Toshiaki; Kiyomatsu, Tomomichi; Kawai, Kazushige; Hata, Keisuke; Kazama, Shinsuke; Yamaguchi, Hironori; Sunami, Eiji; Kitayama, Joji; Fukayama, Masashi; Watanabe, Toshiaki

    2015-01-01

    Anal canal adenoma is an extremely rare disease that has the potential to transform into a malignant tumor. We herein presented a rare case of metachronous multiple adenomas of the anal canal. A 48-year-old woman underwent total colonoscopy following a positive fecal blood test. A 9-mm villous polyp arising from the posterior wall of the anal canal was removed by snare polypectomy. Histologically, the tumor was tubulovillous adenoma with high-grade dysplasia and the cut end was negative for tumor cells. Six years later, an elevated lesion, macroscopically five millimeters in size, was detected in the left wall of the anal canal in a follow-up colonoscopy. Local excision of the tumor was performed, and the lesion was pathologically confirmed to be tubular adenoma with high-grade dysplasia limited to the mucosa. The patient is currently alive without any evidence of recurrence for six months after surgery. Although she had a past history of cervical cancer, the multiple tumors arising in the anal canal were unlikely to be related to human papilloma virus infection. Our case report underscores the importance of careful observations throughout colonoscopy to detect precancerous lesions, particularly in anatomically narrow segments. PMID:26249723

  3. The fouling in the tubular heat exchanger of Algiers refinery

    NASA Astrophysics Data System (ADS)

    Harche, Rima; Mouheb, Abdelkader; Absi, Rafik

    2016-05-01

    Crude oil fouling in refinery preheat exchangers is a chronic operational problem that compromises energy recovery in these systems. Progress is hindered by the lack of quantitative knowledge of the dynamic effects of fouling on heat exchanger transfer and pressure drops. In subject of this work is an experimental determination of the thermal fouling resistance in the tubular heat exchanger of the crude oil preheats trains installed in an Algiers refinery. By measuring the inlet and outlet temperatures and mass flows of the two fluids, the overall heat transfer coefficient has been determined. Determining the overall heat transfer coefficient for the heat exchanger with clean and fouled surfaces, the fouling resistance was calculated. The results obtained from the two cells of exchangers studies, showed that the fouling resistance increased with time presented an exponential evolution in agreement with the model suggested by Kern and Seaton, with the existence of fluctuation caused by the instability of the flow rate and the impact between the particles. The bad cleaning of the heat exchangers involved the absence of the induction period and caused consequently, high values of the fouling resistance in a relatively short period of time.

  4. Steady State Response Analysis of a Tubular Piezoelectric Print Head

    PubMed Central

    Chang, Jiaqing; Liu, Yaxin; Huang, Bo

    2016-01-01

    In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which can be classified as a plane strain problem because the radii of the tubes are considerably smaller than the lengths, is discussed in this paper. The geometric structure and the boundary conditions are all axisymmetric, so a one-dimensional mathematical model is constructed. By solving the model, the deformation field and stress field, as well as the electric potential distribution of the piezoelectric tube and glass tube, are obtained. The results show that the deformations are on the nanometer scale, the hoop stress is larger than the radial stress on the whole, and the potential is not linearly distributed along the radial direction. An experiment is designed to validate these computations. A discussion of the effect of the tubes’ thicknesses on the system deformation status is provided. PMID:26771612

  5. Tubular Overexpression of Angiopoietin-1 Attenuates Renal Fibrosis

    PubMed Central

    Lee, Heedoo; Kim, Yeawon; Liu, Tuoen; Guo, Qiusha; Geminiani, Julio J.; Austin, Paul F.; Chen, Ying Maggie

    2016-01-01

    Emerging evidence has highlighted the pivotal role of microvasculature injury in the development and progression of renal fibrosis. Angiopoietin-1 (Ang-1) is a secreted vascular growth factor that binds to the endothelial-specific Tie2 receptor. Ang-1/Tie2 signaling is critical for regulating blood vessel development and modulating vascular response after injury, but is dispensable in mature, quiescent vessels. Although dysregulation of vascular endothelial growth factor (VEGF) signaling has been well studied in renal pathologies, much less is known about the role of the Ang-1/Tie2 pathway in renal interstitial fibrosis. Previous studies have shown contradicting effects of overexpressing Ang-1 systemically on renal tubulointerstitial fibrosis when different engineered forms of Ang-1 are used. Here, we investigated the impact of site-directed expression of native Ang-1 on the renal fibrogenic process and peritubular capillary network by exploiting a conditional transgenic mouse system [Pax8-rtTA/(TetO)7 Ang-1] that allows increased tubular Ang-1 production in adult mice. Using a murine unilateral ureteral obstruction (UUO) fibrosis model, we demonstrate that targeted Ang-1 overexpression attenuates myofibroblast activation and interstitial collagen I accumulation, inhibits the upregulation of transforming growth factor β1 and subsequent phosphorylation of Smad 2/3, dampens renal inflammation, and stimulates the growth of peritubular capillaries in the obstructed kidney. Our results suggest that Ang-1 is a potential therapeutic agent for targeting microvasculature injury in renal fibrosis without compromising the physiologically normal vasculature in humans. PMID:27454431

  6. A single vibration mode tubular piezoelectric ultrasonic motor.

    PubMed

    He, Siyuan; Chiarot, Paul R; Park, Soonho

    2011-05-01

    A novel tubular ultrasonic motor is presented that uses only a single vibration bending mode of a piezoelectric tube to generate rotation. When the piezoelectric tube bends, the diagonal motion of points on selected areas at the ends of the tube generates forces with tangential components along the same circumferential direction, driving the rotors to rotate. Bi-directional motion is achieved by simply switching the direction of bending. Because only one vibration mode is used, the motor requires only one driving signal and no vibration mode coupling is needed, simplifying the design, fabrication, assembly, and operation of the device. Two prototypes [one with cut-in lead zirconate titanate (PZT) teeth and one with added metal teeth] were built and tested using PZT tubes available to the authors. The tubes have an outside diameter of 6.6 mm, inner diameter of 5.0 mm, and length of 25.4 mm. The working frequencies of the two motors are 27.6 and 23.5 kHz. The motors achieved a maximum no-load speed of 400 rpm and a stall torque of 300 μN·m. PMID:21622060

  7. Gradient-based enhancement of tubular structures in medical images.

    PubMed

    Moreno, Rodrigo; Smedby, Örjan

    2015-12-01

    Vesselness filters aim at enhancing tubular structures in medical images. The most popular vesselness filters are based on eigenanalyses of the Hessian matrix computed at different scales. However, Hessian-based methods have well-known limitations, most of them related to the use of second order derivatives. In this paper, we propose an alternative strategy in which ring-like patterns are sought in the local orientation distribution of the gradient. The method takes advantage of symmetry properties of ring-like patterns in the spherical harmonics domain. For bright vessels, gradients not pointing towards the center are filtered out from every local neighborhood in a first step. The opposite criterion is used for dark vessels. Afterwards, structuredness, evenness and uniformness measurements are computed from the power spectrum in spherical harmonics of both the original and the half-zeroed orientation distribution of the gradient. Finally, the features are combined into a single vesselness measurement. Alternatively, a structure tensor that is suitable for vesselness can be estimated before the analysis in spherical harmonics. The two proposed methods are called Ring Pattern Detector (RPD) and Filtered Structure Tensor (FST) respectively. Experimental results with computed tomography angiography data show that the proposed filters perform better compared to the state-of-the-art. PMID:26277023

  8. Anti-rotation tubular connection for flowlines or the like

    SciTech Connect

    Baugh, B.F.; Panicker, N.N.

    1987-09-15

    This patent describes an anti-rotational, tubular joint for connecting sections of conduits together. The joint consists of a pin member having male threads adapted to be affixed to an end of a section of conduit; a box member having female threads adapted to be affixed to an end of another section of conduit. The female threads cooperate with the male threads to form a connection when the pin member is rotated in a first direction with respect to the box member; a lock sleeve slidably positioned on the box member and movable longitudinally between an unlocked position and a locked position when the pin member is threaded in the box member, the sleeve having longitudinal grooves extending along an upper portion thereby defining resilient fingers; ratchet teeth on each of the fingers; and ratchet teeth on the pin member adapted to cooperate with the ratchet teeth on the fingers when the sleeve is in the locked position to allow rotational movement between the lock sleeve and the pin member in a first direction while preventing rotational movement between the lock sleeve and the pin member in an opposite direction; and means on the lock sleeve and the box member for allowing longitudinal movement while preventing rotational movement.

  9. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    PubMed Central

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG. PMID:25050388

  10. Tubular Overexpression of Angiopoietin-1 Attenuates Renal Fibrosis.

    PubMed

    Singh, Sudhir; Manson, Scott R; Lee, Heedoo; Kim, Yeawon; Liu, Tuoen; Guo, Qiusha; Geminiani, Julio J; Austin, Paul F; Chen, Ying Maggie

    2016-01-01

    Emerging evidence has highlighted the pivotal role of microvasculature injury in the development and progression of renal fibrosis. Angiopoietin-1 (Ang-1) is a secreted vascular growth factor that binds to the endothelial-specific Tie2 receptor. Ang-1/Tie2 signaling is critical for regulating blood vessel development and modulating vascular response after injury, but is dispensable in mature, quiescent vessels. Although dysregulation of vascular endothelial growth factor (VEGF) signaling has been well studied in renal pathologies, much less is known about the role of the Ang-1/Tie2 pathway in renal interstitial fibrosis. Previous studies have shown contradicting effects of overexpressing Ang-1 systemically on renal tubulointerstitial fibrosis when different engineered forms of Ang-1 are used. Here, we investigated the impact of site-directed expression of native Ang-1 on the renal fibrogenic process and peritubular capillary network by exploiting a conditional transgenic mouse system [Pax8-rtTA/(TetO)7 Ang-1] that allows increased tubular Ang-1 production in adult mice. Using a murine unilateral ureteral obstruction (UUO) fibrosis model, we demonstrate that targeted Ang-1 overexpression attenuates myofibroblast activation and interstitial collagen I accumulation, inhibits the upregulation of transforming growth factor β1 and subsequent phosphorylation of Smad 2/3, dampens renal inflammation, and stimulates the growth of peritubular capillaries in the obstructed kidney. Our results suggest that Ang-1 is a potential therapeutic agent for targeting microvasculature injury in renal fibrosis without compromising the physiologically normal vasculature in humans. PMID:27454431

  11. Macroscopic, freestanding, and tubular graphene architectures fabricated via thermal annealing.

    PubMed

    Nguyen, Duc Dung; Suzuki, Seiya; Kato, Shuji; To, Bao Dong; Hsu, Chia Chen; Murata, Hidekazu; Rokuta, Eiji; Tai, Nyan-Hwa; Yoshimura, Masamichi

    2015-03-24

    Manipulation of individual graphene sheets/films into specific architectures at macroscopic scales is crucially important for practical uses of graphene. We present herein a versatile and robust method based on annealing of solid carbon precursors on nickel templates and thermo-assisted removal of poly(methyl methacrylate) under low vacuum of ∼0.6 Pa for fabrication of macroscopic, freestanding, and tubular graphene (TG) architectures. Specifically, the TG architectures can be obtained as individual and woven tubes with a diameter of ∼50 μm, a wall thickness in the range of 2.1-2.9 nm, a density of ∼1.53 mg·cm(-3), a thermal stability up to 600 °C in air, an electrical conductivity of ∼1.48 × 10(6) S·m(-1), and field emission current densities on the order of 10(4) A·cm(-2) at low applied electrical fields of 0.6-0.7 V·μm(-1). These properties show great promise for applications in flexible and lightweight electronics, electron guns, or X-ray tube sources. PMID:25738973

  12. How tubular epithelial cells dictate the rate of renal fibrogenesis?

    PubMed Central

    Louis, Kevin; Hertig, Alexandre

    2015-01-01

    The main threat to a kidney injury, whatever its cause and regardless of whether it is acute or chronic, is the initiation of a process of renal fibrogenesis, since fibrosis can auto-perpetuate and is of high prognostic significance in individual patients. In the clinic, a decrease in glomerular filtration rate correlates better with tubulointerstitial damage than with glomerular injury. Accumulation of the extracellular matrix should not be isolated from other significant cellular changes occurring in the kidney, such as infiltration by inflammatory cells, proliferation of myofibroblasts, obliteration of peritubular capillaries and atrophy of tubules. The aim of this review is to focus on tubular epithelial cells (TEC), which, necessarily involved in the repair process, eventually contribute to accelerating fibrogenesis. In the context of injury, TEC rapidly exhibit phenotypic and functional changes that recall their mesenchymal origin, and produce several growth factors known to activate myofibroblasts. Because they are high-demanding energy cells, TEC will subsequently suffer from the local hypoxia that progressively arises in a microenvironment where the matrix increases and capillaries become rarified. The combination of hypoxia and metabolic acidosis may induce a vicious cycle of sustained inflammation, at the center of which TEC dictate the rate of renal fibrogenesis. PMID:26167460

  13. Fabrication of a molecularly imprinted polymer immobilized membrane with nanopores and its application in determination of β2-agonists in pork samples.

    PubMed

    Qiu, Xiuzhen; Xu, Xian-Yan; Liang, Yong; Hua, Yongbiao; Guo, Huishi

    2016-01-15

    In this paper, a method for the synthesis of ractopamine molecularly imprinted polymers (MIPs) nanotube membranes on anodic alumina oxide (AAO) nanopore surface by atom transfer radical polymerization (ATRP) was presented, in which methacrylic acid (MAA) was selected as functional monomer with a polymerization rate of 1:6 between ractopamine and MAA by the computational investigations. The morphology of MIPs nanotube membranes characterized by scanning electron microscope (SEM) suggested a well growth in the AAO nanopore surface. A series of adsorption experiments revealed that the MIPs nanotube membranes showed better extraction capacity and good selectivity for ractopamine and its analogues than that of non-imprinted polymers (NIPs) nanotube membranes. In order to evaluate the usability of the MIPs nanotube membranes, a methodology by combining MIPs nanotube membranes extraction couple with high performance liquid chromatography (HPLC) detection for the determination of β2-agonists in complex samples was developed. The linear ranges were 10-1000 μg/L for ractopamine, 100-1000 μg/L for clenbuterol, epinephrine and dopamine, and 200-1000 μg/L for terbutaline. The detection limits were within the range of 0.074-0.25 μg/L and the RSDs (n=3) were from 2.8% to 4.3%. The method was successfully applied to the analysis of β2-agonists in spiked real samples, The recoveries of all the β2-agonists at the two concentration levels were found to be within the range of 86.3-97.0% and 82.8-95.7%, respectively. The RSDs were within 2.7-5.7%. The results demonstrated that the proposed method is very suitable for the determination of β2-agonists in pork samples. PMID:26709022

  14. Design and performance of tubular flat-plate solid oxide fuel cell

    SciTech Connect

    Matsushima, T.; Ikeda, D.; Kanagawa, H.

    1996-12-31

    With the growing interest in conserving the environmental conditions, much attention is being paid to Solid Oxide Fuel Cell (SOFC), which has high energy-conversion efficiency. Many organizations have conducted studies on tubular and flat type SOFCs. Nippon Telegraph and Telephone Corporation (NTT) has studied a combined tubular flat-plate SOFC, and already presented the I-V characteristics of a single cell. Here, we report the construction of a stack of this SOFC cell and successful generation tests results.

  15. Hypokalemic quadriparesis and rhabdomyolysis as a rare presentation of distal renal tubular acidosis.

    PubMed

    Ahmad Bhat, Manzoor; Ahmad Laway, Bashir; Mustafa, Farhat; Shafi Kuchay, Mohammad; Mubarik, Idrees; Ahmad Palla, Nazir

    2014-01-01

    Distal renal tubular acidosis is a syndrome of abnormal urine acidification and is characterized by hyperchloremic metabolic acidosis, hypokalemia, hypercalciurea, nephrocalcinosis and nephrolithiasis. Despite the presence of persistent hypokalemia, acute muscular paralysis is rarely encountered in males. Here, we will report an eighteen year old male patient who presented with flaccid quadriparesis and was subsequently found to have rhabdomyolysis, severe short stature, skeletal deformities and primary distal renal tubular acidosis. PMID:25250276

  16. Renal tubular dysfunction presenting as recurrent hypokalemic periodic quadriparesis in systemic lupus erythematosus

    PubMed Central

    Prasad, D.; Agarwal, D.; Malhotra, V.; Beniwal, P.

    2014-01-01

    We report recurrent hypokalemic periodic quadriparesis in a 30-year-old woman. Patient had also symptoms of multiple large and small joint pain, recurrent oral ulceration, photosensitivity and hair loss that were persisting since last 6 months and investigations revealed systemic lupus erythematosus (SLE) with distal tubular acidosis. Our patient was successfully treated with oral potassium chloride, sodium bicarbonate, hydroxychloroquine and a short course of steroids. Thus, tubular dysfunction should be carefully assessed in patients with SLE. PMID:25249723

  17. A new tubular graphene form of a tetrahedrally connected cellular structure.

    PubMed

    Bi, Hui; Chen, I-Wei; Lin, Tianquan; Huang, Fuqiang

    2015-10-21

    3D architectures constructed from a tubular graphene network can withstand repeated >95% compression cycling without damage. Aided by intertubular covalent bonding, this material takes full advantage of the graphene tube's unique attributes, including complete pre- and post-buckling elasticity, outstanding electrical conductivity, and extraordinary physicochemical stability. A highly connected tubular graphene will thus be the ultimate, structurally robust, ultrastrong, ultralight material. PMID:26305918

  18. Incipient renal transplant dysfunction associates with tubular syndecan-1 expression and shedding.

    PubMed

    Adepu, Saritha; Rosman, Colin W K; Dam, Wendy; van Dijk, Marcory C R F; Navis, Gerjan; van Goor, Harry; Bakker, Stephan J L; van den Born, Jacob

    2015-07-15

    Syndecan-1 is a transmembrane heparan sulfate proteoglycan involved in regenerative growth and cellular adhesion. We hypothesized that the induction of tubular syndecan-1 is a repair response to incipient renal damage in apparently stable, uncomplicated renal transplant recipients. We quantified tubular syndecan-1 in unselected renal protocol biopsies taken 1 yr after transplantation. Spearman rank correlation analysis revealed an inverse correlation between tubular syndecan-1 expression and creatinine clearance at the time of biopsy (r = -0.483, P < 0.03). In a larger panel of protocol and indication biopsies from renal transplant recipients, tubular syndecan-1 correlated with tubular proliferation marker Ki67 (r = 0.518, P < 0.0001). In a rat renal transplantation model, 2 mo after transplantation, mRNA expression of syndecan-1 and its major sheddase, A disintegrin and metalloproteinase-17, were upregulated (both P < 0.03). Since shed syndecan-1 might end up in the circulation, in a stable cross-sectional human renal transplant population (n = 510), we measured plasma syndecan-1. By multivariate regression analysis, we showed robust independent associations of plasma syndecan-1 with renal (plasma creatinine and plasma urea) and endothelial function parameters (plasma VEGF-A, all P < 0.01). By various approaches, we were not able to localize syndecan-1 in vessel wall or endothelial cells, which makes shedding of syndecan-1 from the endothelial glycocalyx unlikely. Our data suggest that early damage in transplanted kidneys induces repair mechanisms within the graft, namely, tubular syndecan-1 expression for tubular regeneration and VEGF production for endothelial repair. Elevated plasma syndecan-1 levels in renal transplantation patients might be interpreted as repair/survival factor related to loss of tubular and endothelial function in transplanted kidneys. PMID:25972509

  19. Tubular cell phenotype in HIV-associated nephropathy: role of phospholipid lysophosphatidic acid.

    PubMed

    Ayasolla, Kamesh R; Rai, Partab; Rahimipour, Shai; Hussain, Mohammad; Malhotra, Ashwani; Singhal, Pravin C

    2015-08-01

    Collapsing glomerulopathy and microcysts are characteristic histological features of HIV-associated nephropathy (HIVAN). We have previously reported the role of epithelial mesenchymal transition (EMT) in the development of glomerular and tubular cell phenotypes in HIVAN. Since persistent tubular cell activation of NFκB has been reported in HIVAN, we now hypothesize that HIV may be contributing to tubular cell phenotype via lysophosphatidic acid (LPA) mediated downstream signaling. Interestingly, LPA and its receptors have also been implicated in the tubular interstitial cell fibrosis (TIF) and cyst formation in autosomal dominant polycystic kidney disease (PKD). Primary human proximal tubular cells (HRPTCs) were transduced with either empty vector (EV/HRPTCs), HIV (HIV/HRPTCs) or treated with LPA (LPA/HRPTC). Immunoelectrophoresis of HIV/HRPTCs and LPA/HRPTCs displayed enhanced expression of pro-fibrotic markers: a) fibronectin (2.25 fold), b) connective tissue growth factor (CTGF; 4.8 fold), c) α-smooth muscle actin (α-SMA; 12 fold), and d) collagen I (5.7 fold). HIV enhanced tubular cell phosphorylation of ILK-1, FAK, PI3K, Akt, ERKs and P38 MAPK. HIV increased tubular cell transcriptional binding activity of NF-κB; whereas, a LPA biosynthesis inhibitor (AACOCF3), a DAG kinase inhibitor, a LPA receptor blocker (Ki16425), a NF-κB inhibitor (PDTC) and NFκB-siRNA not only displayed downregulation of a NFκB activity but also showed attenuated expression of profibrotic/EMT genes in HIV milieu. These findings suggest that LPA could be contributing to HIV-induced tubular cell phenotype via NFκB activation in HIVAN. PMID:26079546

  20. Bioinspired Bifunctional Membrane for Efficient Clean Water Generation.

    PubMed

    Liu, Yang; Lou, Jinwei; Ni, Mengtian; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil P; Tao, Peng; Shang, Wen; Deng, Tao

    2016-01-13

    Solving the problems of water pollution and water shortage is an urgent need for the sustainable development of modern society. Different approaches, including distillation, filtration, and photocatalytic degradation, have been developed for the purification of contaminated water and the generation of clean water. In this study, we explored a new approach that uses solar light for both water purification and clean water generation. A bifunctional membrane consisting of a top layer of TiO2 nanoparticles (NPs), a middle layer of Au NPs, and a bottom layer of anodized aluminum oxide (AAO) was designed and fabricated through multiple filtration processes. Such a design enables both TiO2 NP-based photocatalytic function and Au NP-based solar-driven plasmonic evaporation. With the integration of these two functions into a single membrane, both the purification of contaminated water through photocatalytic degradation and the generation of clean water through evaporation were demonstrated using simulated solar illumination. Such a demonstration should also help open up a new strategy for maximizing solar energy conversion and utilization. PMID:26646606

  1. Comparison between small radiation therapy electron beams collimated by Cerrobend and tubular applicators.

    PubMed

    Di Venanzio, Cristina; Marinelli, Marco; Tonnetti, Alessia; Verona-Rinati, Gianluca; Bagalà, Paolo; Falco, Maria Daniela; Guerra, Antonio Stefano; Pimpinella, Maria

    2015-01-01

    The purpose of this study was to compare the dosimetric properties of small field electron beams shaped by circular Cerrobend blocks and stainless steel tubular applicators. Percentage depth dose curves, beam profiles, and output factors of small-size circular fields from 2 to 5 cm diameter, obtained either by tubular applicators and Cerrobend blocks, were measured for 6, 10, and 15 MeV electron beam energies. All measurements were performed using a PTW microDiamond 60019 premarket prototype. An overall similar behavior between the two collimating systems can be observed in terms of PDD and beam profiles. However, Cerrobend collimators produce a higher bremsstrahlung background under irradiation with high-energy electrons. In such irradiation condition, larger output factors are observed for tubular applicators. Similar dosimetric properties are observed using circular Cerrobend blocks and stainless steel tubular applicators at lower beam energies. However, Cerrobend collimators allow the delivery of specific beam shapes, conformed to the target area. On the other hand, in high-energy irradiation conditions, tubular applicators produce a lower bremsstrahlung contribution, leading to lower doses outside the target volume. In addition, the higher output factors observed at high energies for tubular applicators lead to reduced treatment times. PMID:25679175

  2. Deformation measurement method for spatial complex tubular joints based on photogrammetry

    NASA Astrophysics Data System (ADS)

    Shi, Bao-Quan; Liang, Jin; Xiao, Zhen-Zhong; Zhang, Xiao-Qiang; Liu, Qing

    2010-12-01

    The destruction of spatial complex tubular joints may lead to failure of the whole tubular structure, thus it is necessary to analyze the mechanical properties of spatial complex tubular joint. In this paper, a novel method based on close range photogrammetry to accurately measure the three-dimensional (3D) deformation of spatial complex tubular joints during loading test is proposed. Artificial targets are pasted on the deformation area before loading. The 3D coordinates of these targets are reconstructed by analyzing the images captured at each stage, and the coordinate systems of different stages are registered together by means of global transformation points. The whole field 3D deformation under different load levels is then obtained by tracking the homonymous targets among different stages. It is helpful for further analysis of the mechanical properties. Two different precision evaluation experiments indicate that the proposed method could achieve accuracy of 0.1mm/m. Two full scale tubular joints are tested and a feasible solution for improving the load carrying capacity of the tested tubular joints is thus obtained as per the measured results. For comparison, finite element analysis is employed to predict the deformation in a traditional way. The deformation tendency measured by two methods agrees well.

  3. Multicomponent Transport through Realistic Zeolite Membranes: Characterization & Transport in Nanoporous Networks

    SciTech Connect

    William C. Conner

    2007-08-02

    These research studies focused on the characterization and transport for porous solids which comprise both microporosity and mesoporosity. Such materials represent membranes made from zeolites as well as for many new nanoporous solids. Several analytical sorption techniques were developed and evaluated by which these multi-dimensional porous solids could be quantitatively characterized. Notably an approach by which intact membranes could be studied was developed and applied to plate-like and tubular supported zeolitic membranes. Transport processes were studied experimentally and theoretically based on the characterization studies.

  4. Assessment of the place of tubular reabsorption of phosphorus in the diagnosis of osteopenia of prematurity

    PubMed Central

    Acar, Duygu Besnili; Kavuncuoğlu, Sultan; Çetinkaya, Merih; Petmezci, Ercüment; Dursun, Mesut; Korkmaz, Orhan; Altuncu, Emel Kayrak

    2015-01-01

    Aim: In this study, we aimed to investigate the utility of tubular reabsorption of phosphorus in the diagnosis of osteopenia of prematurity in addition to biochemical markers. Materials and Method: Premature babies with a gestational age of ≤32 weeks and/or a birth weight of ≤1 500 g who were hospitalized in the neonatal intensive care unit between June 2009 and March 2011 were included in the study. These babies were evaluated at the 40th gestational week and serum calcium, phosphorus, alkaline phosphatase, urea, creatinine, urinary calcium and phosphorus levels were measured and tubular reabsorption of phosphorus was determined. The subjects who had bone graphy findings and/or an alkaline phosphatase level of >400IU/L and a phosphorus value of <3.5 mg/dL were considered osteopenic. The levels of tubular reabsorption of phosphorus of the osteopenic patients were compared with the ones of the non-osteopenic patients. The study was initiated after obtaining ethics committee approval (date: 04.29.2009/213). Results: During the study period, a total of 698 premature babies were hospitalized in our neonatology unit. A diagnosis of osteopenia of prematurity was made in 24 of 190 subjects who met the study criteria. The level of tubular reabsorption of phosphorus was compared with the serum calcium, phosphorus and alkaline phosphatase levels measured at the 40th gestational week and alkaline phosphatase was found to be significantly increased in the group with a high tubular reabsorption of phosphorus (≥%95). When the subjects with a phosphorus level of <3.5 mg/dL and an alkaline phosphatase level of >499 IU were compared with the newborns who were found to have a tubular reabsorption of phosphorus of ≥%95 for the objective of evaluating the specificity and sensitivity of tubular reabsorption of phosphorus, the sensitivity, specificity, positive predictive value and negative predictive value of tubular reabsorption of phosphorus in the diagnosis of osteopenia

  5. Design, construction and evaluation of solarized airlift tubular photobioreactor

    NASA Astrophysics Data System (ADS)

    Bahadur, A.; Zubair, M.; Khan, M. B.

    2013-06-01

    An innovative photobioreactor is developed for growing algae in simulated conditions. The proposed design comprises of a continuous tubular irradiance loop and air induced liquid circulation with gas separation through air lift device. The unique features of air lift system are to ensure the shear free circulation of sensitive algal culture and induce light/dark cycles to the photosynthetic micro-organisms. The design strategy employs to model and construct a 20-liter laboratory scale unit using Boro-silicate glass tubing. The material is selected to ensure maximum photon transmission. All components of the device are designed to have flexibility to be replaced with an alternative design, providing fair chance of modification for future investigators. The principles of fluid mechanics are applied to describe geometrical attributes of the air lift system. Combination of LEDs and Florescent tube lights (Warm white) were used to illuminate the photosynthesis reaction area providing a possibility to control both illumination duration and light intensity. 200 Watt Solar PV system is designed to power up the device which included air pump (100 Watt) and illumination system (100 Watt). Algal strain Chlorella sp was inoculated in photobioreactor which was sparged with air and carbon dioxide. The growth was sustained in the batch mode with daily monitoring of temperature, pH and biomass concentration. The novel photobioreactor recorded a maximum experimental average yield of 0.65 g/l.day (11.3 g/m2.day) as compared to theoretical modeled yield of 0.82 g/l.day (14.26 g/m2.day), suggesting the device can be efficiently and cost-effectively employed in the production of algal biomass for biofuels, concomitantly mitigating CO2.

  6. [Itai-itai disease: cadmium-induced renal tubular osteomalacia].

    PubMed

    Aoshima, Keiko

    2012-01-01

    Cadmium (Cd) is one of the most toxic elements to which humans could be exposed at work or in the environment. The outbreak of itai-itai disease, which is the most severe stage of chronic Cd poisoning, occurred in the Cd-polluted Jinzu River basin in Toyama. In this area, the river was contaminated by slag from a mine upstream; as a consequence, the soil in rice paddies was polluted with heavy metals including Cd through irrigation water from around 1910 to the 1960s. The government of Toyama prefecture carried out an extensive survey on Cd concentration in rice and soil of the paddy fields and declared that the upper layer of a total of 1500 ha of paddy fields should be replaced by nonpolluted soil. Then, an intervention program of soil replacement in the polluted paddy fields was continually carried out from 1980 to 2011. As a result, Cd concentration in rice markedly decreased. The kidney is the organ critically affected after long-term exposure to Cd. Proximal tubular dysfunction (RTD) has been found among the inhabitants of the Jinzu River basin. The very recent report by the Environmental Agency in Japan in 2009 has disclosed that b2-microglobulinuria with RTD is still found at a high prevalence among the inhabitants of the Jinzu River basin of both sexes. Twenty patients with itai-itai disease (1 male and 19 females), who attended our hospital and received medical examination during 2000 to 2008, had applied for recognition as itai-itai disease patients to the government of Toyama prefecture. In this paper, the recent epidemiological and clinical features of itai-itai disease are discussed on the basis of a review of the cases of these 19 female patients. PMID:23095355

  7. Perfluorooctanesulfonate Mediates Renal Tubular Cell Apoptosis through PPARgamma Inactivation

    PubMed Central

    Chou, Hsiu-Chu; Chang, Chih-Cheng; Lo, Hau-Yin; Juan, Shu-Hui

    2016-01-01

    Perfluorinated chemicals (PFCs) are ubiquitously distributed in the environments including stainless pan-coating, raincoat, fire extinguisher, and semiconductor products. The PPAR family has been shown to contribute to the toxic effects of PFCs in thymus, immune and excretory systems. Herein, we demonstrated that perfluorooctanesulfonate (PFOS) caused cell apoptosis through increasing ratio of Bcl-xS/xL, cytosolic cytochrome C, and caspase 3 activation in renal tubular cells (RTCs). In addition, PFOS increased transcription of inflammatory cytokines (i.e., TNFα, ICAM1, and MCP1) by NFκB activation. Conversely, PFOS reduced the mRNA levels of antioxidative enzymes, such as glutathione peroxidase, catalase, and superoxide dismutase, as a result of reduced PPARγ transactivational activity by using reporter and chromatin immuoprecipitation (ChIP) assays. PFOS reduced the protein interaction between PPARγ and PPARγ coactivator-1 alpha (PGC1α) by PPARγ deacetylation through Sirt1 upregulation, of which the binding of PPARγ and PGC1α to a peroxisome proliferator response element (PPRE) in the promoter regions of these antioxidative enzymes was alleviated in the ChIP assay. Furthermore, Sirt1 also deacetylated p53 and then increased the binding of p53 to Bax, resulting in increased cytosolic cytochrome C. The effect of PPARγ inactivation by PFOS was validated using the PPARγ antagonist GW9662, whereas the adverse effects of PFOS were prevented by PPARγ overexpression and activators, rosiglitozone and L-carnitine, in RTCs. The in vitro finding of protective effect of L-carnitine was substantiated in vivo using Balb/c mice model subjected to PFOS challenge. Altogether, we provide in vivo and in vitro evidence for the protective mechanism of L-carnitine in eliminating PFOS-mediated renal injury, at least partially, through PPARγ activation. PMID:27171144

  8. Proteinuria Increases Plasma Phosphate by Altering Its Tubular Handling.

    PubMed

    de Seigneux, Sophie; Courbebaisse, Marie; Rutkowski, Joseph M; Wilhelm-Bals, Alexandra; Metzger, Marie; Khodo, Stellor Nlandu; Hasler, Udo; Chehade, Hassib; Dizin, Eva; Daryadel, Arezoo; Stengel, Bénedicte; Girardin, E; Prié, Dominique; Wagner, Carsten A; Scherer, Philipp E; Martin, Pierre-Yves; Houillier, Pascal; Feraille, Eric

    2015-07-01

    Proteinuria and hyperphosphatemia are cardiovascular risk factors independent of GFR. We hypothesized that proteinuria induces relative phosphate retention via increased proximal tubule phosphate reabsorption. To test the clinical relevance of this hypothesis, we studied phosphate handling in nephrotic children and patients with CKD. Plasma fibroblast growth factor 23 (FGF-23) concentration, plasma phosphate concentration, and tubular reabsorption of phosphate increased during the proteinuric phase compared with the remission phase in nephrotic children. Cross-sectional analysis of a cohort of 1738 patients with CKD showed that albuminuria≥300 mg/24 hours is predictive of higher phosphate levels, independent of GFR and other confounding factors. Albuminuric patients also displayed higher plasma FGF-23 and parathyroid hormone levels. To understand the molecular mechanisms underlying these observations, we induced glomerular proteinuria in two animal models. Rats with puromycin-aminonucleoside-induced nephrotic proteinuria displayed higher renal protein expression of the sodium-phosphate co-transporter NaPi-IIa, lower renal Klotho protein expression, and decreased phosphorylation of FGF receptor substrate 2α, a major FGF-23 receptor substrate. These findings were confirmed in transgenic mice that develop nephrotic-range proteinuria resulting from podocyte depletion. In vitro, albumin did not directly alter phosphate uptake in cultured proximal tubule OK cells. In conclusion, we show that proteinuria increases plasma phosphate concentration independent of GFR. This effect relies on increased proximal tubule NaPi-IIa expression secondary to decreased FGF-23 biologic activity. Proteinuria induces elevation of both plasma phosphate and FGF-23 concentrations, potentially contributing to cardiovascular disease. PMID:25349200

  9. The Dynamical Evolution of A Tubular Leonid Persistent Train

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Nugent, David; Plane, John M. C.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The dynamical evolution of the persistent train of a bright Leonid meteor was examined for evidence of the source of the luminosity and the physical conditions in the meteor path. The train consisted of two parallel somewhat diffuse luminous tracks, interpreted as the walls of a tube. A general lack of wind shear along the trail allowed these structures to remain intact for nearly 200 s, from which it was possible to determine that the tubular structure expanded at a near constant 10.5 m/s, independent of altitude between 86 and 97 km. An initial fast decrease of train intensity below 90 km was followed by an increase in intensity and then a gradual decrease at longer times, whereas at high attitudes the integrated intensity was nearly constant with time. These results are compared to a model that describes the dynamical evolution of the train by diffusion, following an initial rapid expansion of the hot gaseous trail behind the meteoroid. The train luminosity is produced by O ((sup 1)S) emission at 557 nm, driven by elevated atomic O levels produced by the meteor impact, as well as chemiluminescent reactions of the ablated metals Na and Fe with O3. Ozone is rapidly removed within the train, both by thermal decomposition and catalytic destruction by the metallic species. Hence, the brightest emission occurs at the edge of the train between outwardly diffusing metallic species and inwardly diffusing O3. Although the model is able to account plausibly for a number of characteristic features of the train evolution, significant discrepancies remain that cannot easily be resolved.

  10. The Dynamical Evolution of a Tubular Leonid Persistent Train

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter; Nugent, David; Plane, John M. C.

    The dynamical evolution of the persistent train of a bright Leonid meteor was examined for evidence of the source of the luminosity and the physical conditions in the meteor path. The train consisted of two parallel somewhat diffuse luminous tracks, interpreted as the walls of a tube. A general lack of wind shear along the trail allowed these structures to remain intact for nearly 200 s, from which it was possible to determine that the tubular structure expanded at a near constant 10.5 ms^-1, independent of altitude between 86 and 97 km. An initial fast decrease of train intensity below 90 km was followed by an increase in intensity and then a gradual decrease at longer times, whereas at high altitudes the integrated intensity was nearly constant with time. These results are compared to a model that describes the dynamical evolution of the train by diffusion, following an initial rapid expansion of the hot gaseous trail behind the meteoroid. The train luminosity is produced by O (^1S) emission at 557 nm, driven by elevated atomic O levels produced by the meteor impact, as well as chemiluminescent reactions of the ablated metals Na and Fe with O_3. Ozone is rapidly removed within the train, both by thermal decomposition and catalytic destruction by the metallic species. Hence, the brightest emission occurs at the edge of the train between outwardly diffusing metallic species and inwardly diffusing O_3. Although the model is able to account plausibly for a number of characteristic features of the train evolution, significant discrepancies remain that cannot casily be resolved.

  11. Perfluorooctanesulfonate Mediates Renal Tubular Cell Apoptosis through PPARgamma Inactivation.

    PubMed

    Wen, Li-Li; Lin, Chien-Yu; Chou, Hsiu-Chu; Chang, Chih-Cheng; Lo, Hau-Yin; Juan, Shu-Hui

    2016-01-01

    Perfluorinated chemicals (PFCs) are ubiquitously distributed in the environments including stainless pan-coating, raincoat, fire extinguisher, and semiconductor products. The PPAR family has been shown to contribute to the toxic effects of PFCs in thymus, immune and excretory systems. Herein, we demonstrated that perfluorooctanesulfonate (PFOS) caused cell apoptosis through increasing ratio of Bcl-xS/xL, cytosolic cytochrome C, and caspase 3 activation in renal tubular cells (RTCs). In addition, PFOS increased transcription of inflammatory cytokines (i.e., TNFα, ICAM1, and MCP1) by NFκB activation. Conversely, PFOS reduced the mRNA levels of antioxidative enzymes, such as glutathione peroxidase, catalase, and superoxide dismutase, as a result of reduced PPARγ transactivational activity by using reporter and chromatin immuoprecipitation (ChIP) assays. PFOS reduced the protein interaction between PPARγ and PPARγ coactivator-1 alpha (PGC1α) by PPARγ deacetylation through Sirt1 upregulation, of which the binding of PPARγ and PGC1α to a peroxisome proliferator response element (PPRE) in the promoter regions of these antioxidative enzymes was alleviated in the ChIP assay. Furthermore, Sirt1 also deacetylated p53 and then increased the binding of p53 to Bax, resulting in increased cytosolic cytochrome C. The effect of PPARγ inactivation by PFOS was validated using the PPARγ antagonist GW9662, whereas the adverse effects of PFOS were prevented by PPARγ overexpression and activators, rosiglitozone and L-carnitine, in RTCs. The in vitro finding of protective effect of L-carnitine was substantiated in vivo using Balb/c mice model subjected to PFOS challenge. Altogether, we provide in vivo and in vitro evidence for the protective mechanism of L-carnitine in eliminating PFOS-mediated renal injury, at least partially, through PPARγ activation. PMID:27171144

  12. Draining of the SUNPAK/sup TM/ evacuated tubular collector

    SciTech Connect

    Pei, Y.K.

    1980-05-01

    A program has been completed which demonstrates the capability of draining the present liquid series flow SUNPAK/sup TM/ evacuated tubular collector. The benefits which are derived include the avoidance of potential problems associated with liquid boil-out during system failure and the avoidance of collector freeze up. Additional benefits derived from a fully drained collector are the avoidance of significant heat losses during overnight periods, safe access to the collector for maintenance at any time and ability to dissipate excess heat through dry stagnation of the collector during shut down periods. A simple modification to the series flow SUNPAK/sup TM/ collector module arrangement was developed and demonstrated through the full scale testing of a two bank-six module arrangement. The necessary changes can be implemented at a minimum expenditure of time and cost. The extensive field service experience which has been accumulated with the liquid series flow SUNPAK/sup TM/ collector is directly applicable to the drainable configuration. The program included the investigation of an alternate approach to the series flow SUNPAK/sup TM/ solution. The intra module parallel flow concept was demonstrated through the proof of concept phase of effort. The solution investigated incorporated a batch flow rather than a continuous flow mode of the cooling fluid. The solution required an extensive design modification of the existing SUNPAK/sup TM/ collector manifold. During the redesign effort, other desired mechanical features of the manifold were incorporated to improve the physical characteristics, to improve safety and reliability and to reduce the potential cost of future SUNPAK/sup TM/ collector arrays.

  13. Effect of air flow on tubular solar still efficiency

    PubMed Central

    2013-01-01

    Background An experimental work was reported to estimate the increase in distillate yield for a compound parabolic concentrator-concentric tubular solar still (CPC-CTSS). The CPC dramatically increases the heating of the saline water. A novel idea was proposed to study the characteristic features of CPC for desalination to produce a large quantity of distillate yield. A rectangular basin of dimension 2 m × 0.025 m × 0.02 m was fabricated of copper and was placed at the focus of the CPC. This basin is covered by two cylindrical glass tubes of length 2 m with two different diameters of 0.02 m and 0.03 m. The experimental study was operated with two modes: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively. Findings The experimental study was operated with two modes: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. Conclusions On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively. PMID:23587020

  14. 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.

  15. A selective and sensitive stability-indicating HPLC method for the validated assay of etoposide from commercial dosage form and polymeric tubular nanocarriers.

    PubMed

    Algan, Aslihan Hilal; Gumustas, Mehmet; Karatas, Aysegul; Ozkan, Sibel A

    2016-05-30

    Etoposide is a topoisomerase II enzyme inhibitor type chemotherapeutic agent which is widely used in the therapy of various cancers. Its short half-life and toxicity to normal tissues are the major drawbacks in its clinical applications. Polymeric nanoparticulate drug delivery systems are rational carriers to deliver etoposide with higher efficiency and fewer side effects. In addition tubular shaped drug carriers are found to show a great potential for drug delivery on the basis of promising results regarding particle shape and cellular uptake. In this study, etoposide loaded polymeric tubular nanocarriers have been developed by template wetting method using porous anodic aluminum oxide membranes as templates. The developed poly(methyl methacrylate) nanocarriers were evaluated for structural analysis, in vitro drug release studies and drug release kinetics. Accurate and reliable determination of the drug release from newly developed nanocarriers, is of great importance. For this reason a selective and sensitive reversed phase liquid chromatography method was developed and fully validated from the point of system suitability, specificity, linearity and range, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and robustness for the reliable determination of etoposide. Stability indicating capability was shown with forced degradation studies and the chromatographic conditions were optimized on ACE 5C18 (150 mm × 4.6mm I.D., 5 μm) analytical column. Related to the calibration results ETP was found linear in the range between 0.2 from 100 μg mL(-1) with the LOD as 0.015 μg.mL(-1). The resultant conditions were applied for the selective and sensitive determination of etoposide from its commercial dosage form with the high accuracy values (99.82-100.65%). The method was successfully detected assay of etoposide release from newly developed polymeric tubular nanocarriers, which was found as 72.2% at the end of 24h. PMID:26971031

  16. Protective effects of Ezrin on cold storage preservation injury in the pig kidney proximal tubular epithelial cell line [LLC-PK1

    PubMed Central

    Tian, Tao; Lindell, Susanne L.; Henderson, Scott C.; Mangino, Martin J.

    2009-01-01

    Background Renal damage caused by cold preservation and warm reperfusion has been well documented and involves tissue edema, cell swelling, ATP depletion, calcium toxicity, and oxidative stress. However, more common proximal mechanisms have not been identified, which may limit the development of effective clinical treatment strategies. Previous work indicates that many cytoskeletal structures are affected by cold preservation and reperfusion, including membrane rich ezrin associated complexes. The aim of this study was to investigate whether the sub-lamellar cytoskeletal protein ezrin is causally involved in cold preservation injury in renal tubule epithelial cells. Methods We created a stably transfected cell Line [LLC-EZ] using the pig kidney proximal tubular epithelial cell line [LLC-PK1], which constitutively over-expresses wild-type ezrin. These cells were cold stored in UW solution and reperfused in-vitro to model renal tubule preservation injury, which was assessed by biochemical, metabolic, functional, and structural end points. Results Over-expression of ezrin increased cell viability (LDH release), mitochondrial activity (ATP synthesis, dehydrogenase activity, and inner mitochondrial membrane potential), and protected the structure of cell membrane microvilli and mitochondria after cold storage preservation injury. Reperfusion-induced apoptosis was also significantly reduced in LLC-EZ cells over-expressing ezrin. Conclusions Enhanced ezrin expression protects tubule epithelial cells from cold storage preservation injury, possibly by membrane or mitochondrial mechanisms. PMID:19461485

  17. Urinary excretion of beta 2-glycoprotein-1 (apolipoprotein H) and other markers of tubular malfunction in "non-tubular" renal disease.

    PubMed Central

    Flynn, F. V.; Lapsley, M.; Sansom, P. A.; Cohen, S. L.

    1992-01-01

    AIM: To determine whether urinary beta 2-glycoprotein-1 assays can provide improved discrimination between chronic renal diseases which are primarily of tubular or glomerular origin. METHODS: Urinary beta 2-glycoprotein-1, retinol-binding protein, alpha 1-microglobulin, beta 2-microglobulin, N-acetyl-beta-D-glucosa-minidase and albumin were measured in 51 patients with primary glomerular disease, 23 with obstructive nephropathy, and 15 with polycystic kidney disease, and expressed per mmol of creatinine. Plasma beta 2-glycoprotein-1 was assayed in 52 patients and plasma creatinine in all 89. The findings were compared between the diagnostic groups and with previously published data relating to primary tubular disorders. RESULTS: All 31 patients with plasma creatinine greater than 200 mumol/l excreted increased amounts of beta 2-glycoprotein-1, retinol-binding protein, and alpha 1-microglobulin, and 29 had increased N-acetyl-beta-D-glucosaminidase; the quantities were generally similar to those found in comparable patients with primary tubular pathology. Among 58 with plasma creatinine concentrations under 200 mumol/l, increases in beta 2-glycoprotein-1, retinol-binding protein, and alpha 1-microglobulin excretion were less common and much smaller, especially in those with obstructive nephropathy and polycystic disease. The ratios of the excretion of albumin to the other proteins provided the clearest discrimination between the patients with glomerular or tubular malfunction, but an area of overlap was present which embraced those with obstructive nephropathy and polycystic disease. CONCLUSIONS: Increased excretion of beta 2-glycoprotein-1 due to a raised plasma concentration or diminution of tubular reabsorption, or both, is common in all the forms of renal disease investigated, and both plasma creatinine and urinary albumin must be taken into account when interpreting results. Ratios of urinary albumin: beta 2-glycoprotein-1 greater than 1000 are highly suggestive

  18. Dynamics of membrane nanotubes coated with I-BAR

    PubMed Central

    Barooji, Younes F.; Rørvig-Lund, Andreas; Semsey, Szabolcs; Reihani, S. Nader S.; Bendix, Poul M.

    2016-01-01

    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes. I-BAR decorated tubes were quantified to have a diameter of ~50 nm and exhibit no stiffening relative to protein free tubes of the same diameter. At high protein density the tubes are immobile whereas at lower density the tubes diffuse freely on the surface of the GUV. Bleaching experiments of the fluorescently tagged I-BAR confirmed that the mobility of the tubes correlates with the mobility of the I-BAR on the GUV membrane. Finally, at low density of I-BAR the protein upconcentrates within tubes protruding into the GUVs. This implies that I-BAR exhibits strong preference for negatively curved membranes. PMID:27444356

  19. Dynamics of membrane nanotubes coated with I-BAR.

    PubMed

    Barooji, Younes F; Rørvig-Lund, Andreas; Semsey, Szabolcs; Reihani, S Nader S; Bendix, Poul M

    2016-01-01

    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes. I-BAR decorated tubes were quantified to have a diameter of ~50 nm and exhibit no stiffening relative to protein free tubes of the same diameter. At high protein density the tubes are immobile whereas at lower density the tubes diffuse freely on the surface of the GUV. Bleaching experiments of the fluorescently tagged I-BAR confirmed that the mobility of the tubes correlates with the mobility of the I-BAR on the GUV membrane. Finally, at low density of I-BAR the protein upconcentrates within tubes protruding into the GUVs. This implies that I-BAR exhibits strong preference for negatively curved membranes. PMID:27444356

  20. Dynamics of membrane nanotubes coated with I-BAR

    NASA Astrophysics Data System (ADS)

    Barooji, Younes F.; Rørvig-Lund, Andreas; Semsey, Szabolcs; Reihani, S. Nader S.; Bendix, Poul M.

    2016-07-01

    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes. I-BAR decorated tubes were quantified to have a diameter of ~50 nm and exhibit no stiffening relative to protein free tubes of the same diameter. At high protein density the tubes are immobile whereas at lower density the tubes diffuse freely on the surface of the GUV. Bleaching experiments of the fluorescently tagged I-BAR confirmed that the mobility of the tubes correlates with the mobility of the I-BAR on the GUV membrane. Finally, at low density of I-BAR the protein upconcentrates within tubes protruding into the GUVs. This implies that I-BAR exhibits strong preference for negatively curved membranes.

  1. Mitochondrial outer membrane forms bridge between two mitochondria in Arabidopsis thaliana.

    PubMed

    Yamashita, Akihiro; Fujimoto, Masaru; Katayama, Kenta; Tsutsumi, Nobuhiro; Arimura, Shin-Ichi

    2016-05-01

    Mitochondria are double-membrane organelles that move around and change their shapes dynamically. In plants, the dynamics of the outer membrane is not well understood. We recently demonstrated that mitochondria had tubular protrusions of the outer membrane with little or no matrix, called MOPs (mitochondrial outer-membrane protrusions; MOPs). Here we show that a MOP can form a bridge between two mitochondria in Arabidopsis thaliana. The bridge does not appear to involve the inner membranes. Live imaging revealed stretching of the MOP bridge, demonstrating the flexibility of the outer membrane. Mitochondria frequently undergo fission and fusion. These observations raise the possibility that MOPs bridges have a role in these processes. PMID:27031262

  2. Microtubule Motors Power Plasma Membrane Tubulation in Clathrin-Independent Endocytosis

    PubMed Central

    Day, Charles A; Baetz, Nicholas W; Copeland, Courtney A; Kraft, Lewis J; Han, Bing; Tiwari, Ajit; Drake, Kimberly R; De Luca, Heidi; Chinnapen, Daniel J-F; Davidson, Michael W; Holmes, Randall K; Jobling, Michael G; Schroer, Trina A; Lencer, Wayne I; Kenworthy, Anne K

    2015-01-01

    How the plasma membrane is bent to accommodate clathrin-independent endocytosis remains uncertain. Recent studies suggest Shiga and cholera toxin induce membrane curvature required for their uptake into clathrin-independent carriers by binding and cross-linking multiple copies of their glycosphingolipid receptors on the plasma membrane. But it remains unclear if toxin-induced sphingolipid crosslinking provides sufficient mechanical force for deforming the plasma membrane, or if host cell factors also contribute to this process. To test this, we imaged the uptake of cholera toxin B-subunit into surface-derived tubular invaginations. We found that cholera toxin mutants that bind to only one glycosphingolipid receptor accumulated in tubules, and that toxin binding was entirely dispensable for membrane tubulations to form. Unexpectedly, the driving force for tubule extension was supplied by the combination of microtubules, dynein and dynactin, thus defining a novel mechanism for generating membrane curvature during clathrin-independent endocytosis. PMID:25690058

  3. The influence of polymeric membrane gas spargers on hydrodynamics and mass transfer in bubble column bioreactors.

    PubMed

    Tirunehe, Gossaye; Norddahl, B

    2016-04-01

    Gas sparging performances of a flat sheet and tubular polymeric membranes were investigated in 3.1 m bubble column bioreactor operated in a semi batch mode. Air-water and air-CMC (Carboxymethyl cellulose) solutions of 0.5, 0.75 and 1.0 % w/w were used as interacting gas-liquid mediums. CMC solutions were employed in the study to simulate rheological properties of bioreactor broth. Gas holdup, bubble size distribution, interfacial area and gas-liquid mass transfer were studied in the homogeneous bubbly flow hydrodynamic regime with superficial gas velocity (U G) range of 0.0004-0.0025 m/s. The study indicated that the tubular membrane sparger produced the highest gas holdup and densely populated fine bubbles with narrow size distribution. An increase in liquid viscosity promoted a shift in bubble size distribution to large stable bubbles and smaller specific interfacial area. The tubular membrane sparger achieved greater interfacial area and an enhanced overall mass transfer coefficient (K La) by a factor of 1.2-1.9 compared to the flat sheet membrane. PMID:26857370

  4. IRSp53 senses negative membrane curvature and phase separates along membrane tubules

    PubMed Central

    Prévost, Coline; Zhao, Hongxia; Manzi, John; Lemichez, Emmanuel; Lappalainen, Pekka; Callan-Jones, Andrew; Bassereau, Patricia

    2015-01-01

    BAR domain proteins contribute to membrane deformation in diverse cellular processes. The inverted-BAR (I-BAR) protein IRSp53, for instance, is found on the inner leaflet of the tubular membrane of filopodia; however its role in the formation of these structures is incompletely understood. Here we develop an original assay in which proteins are encapsulated in giant unilamellar vesicles connected to membrane nanotubes. Our results demonstrate that I-BAR dimers sense negative membrane curvature. Experiment and theory reveal that the I-BAR displays a non-monotonic sorting with curvature, and expands the tube at high imposed tension while constricting it at low tension. Strikingly, at low protein density and tension, protein-rich domains appear along the tube. This peculiar behaviour is due to the shallow intrinsic curvature of I-BAR dimers. It allows constriction of weakly curved membranes coupled to local protein enrichment at biologically relevant conditions. This might explain how IRSp53 contributes in vivo to the initiation of filopodia. PMID:26469246

  5. A NOVEL MEMBRANE REACTOR FOR DIRECT HYDROGEN PRODUCTION FROM COAL

    SciTech Connect

    Shain Doong; Estela Ong; Mike Atroshenko; Mike Roberts; Francis Lau

    2004-04-26

    Gas Technology Institute is developing a novel concept of membrane gasifier for high efficiency, clean and low cost production of hydrogen from coal. The concept incorporates a hydrogen-selective membrane within a gasification reactor for direct extraction of hydrogen from coal synthesis gases. The objective of this project is to determine the technical and economic feasibility of this concept by screening, testing and identifying potential candidate membranes under high temperature, high pressure, and harsh environments of the coal gasification conditions. The best performing membranes will be selected for preliminary reactor design and cost estimates. To evaluate the performances of the candidate membranes under the gasification conditions, a high temperature/high pressure hydrogen permeation unit will be constructed in this project. During this reporting period, the mechanical construction of the permeation unit was completed. Commissioning and shake down tests are being conducted. The unit is capable of operation at temperatures up to 1100 C and pressures to 60 atm for evaluation of ceramic membranes such as mixed ionic conducting membrane. The membranes to be tested will be in disc form with a diameter of about 3 cm. Operation at these high temperatures and high hydrogen partial pressures will demonstrate commercially relevant hydrogen flux, 10{approx}50 cc/min/cm{sup 2}, from the membranes made of the perovskite type of ceramic material. Preliminary modeling was also performed for a tubular membrane reactor within a gasifier to estimate the required membrane area for a given gasification condition. The modeling results will be used to support the conceptual design of the membrane reactor.

  6. Fabrication of free standing anodic titanium oxide membranes with clean surface using recycling process.

    PubMed

    Meng, Xianhui; Lee, Tae-Young; Chen, Huiyu; Shin, Dong-Wook; Kwon, Kee-Won; Kwon, Sang Jik; Yoo, Ji-Beom

    2010-07-01

    Large area of self-organized, free standing anodic titanium oxide (ATO) nanotube membranes with clean surfaces were facilely prepared to desired lengths via electrochemical anodization of highly pure Ti sheets in an ethylene glycol electrolyte, with a small amount of NH4F and H2O at 50 V, followed by self-detachment of the ATO membrane from the Ti substrate using recycling processes. In the first anodization step, the nanowire oxide layer existed over the well-arranged ATO nanotube. After sufficiently rinsing with water, the whole ATO layer was removed from the Ti sheet by high pressure N2 gas, and a well-patterned dimple layer with a thickness of about 30 nm existed on the Ti substrate. By using these naturally formed nano-scale pits as templates, in the second and third anodization process, highly ordered, vertically aligned, and free standing ATO membranes with the anodic aluminum oxide (AAO)-like clean surface were obtained. The inter-pore distance and diameter was 154 +/- 2 nm and 91+/- 2 nm, the tube arrays lengths for 25 and 46 hours were 44 and 70 microm, respectively. The present study demonstrates a simple approach to producing high quality, length controllable, large area TiO2 membrane. PMID:21128409

  7. [Tubular rectum and colon resection. A new operative method for the removal of large adenomas and low-risk carcinomas].

    PubMed

    Gall, F P

    1982-08-01

    A new operative method for the removal of large sessile tubular or villous adenomas and small early carcinomas of the low risk type by a "tubular" colonic or rectal resection is described. The term "tubular" applies to a short segmental resection of the colon or rectum with complete preservation of the mesocolon or mesorectum and the marginal or superior hemorrhoidal artery. This tubular resection has been used by us since 1981 in 11 patients (7 adenomas, 3 adenocarcinomas and one carcinoid). There was no suture line leakage. No lethality and so far no recurrence. The advantages of this new operative technique over conventional methods are discussed in detail. PMID:7128268

  8. 78 FR 9033 - Certain Oil Country Tubular Goods From the People's Republic of China: Amended Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-07

    ...: Final Results of Antidumping Duty Administrative Review; 2010-2011, 77 FR 74644 (December 17, 2012... petitioner) and American Tubular Products, LLC (``ATP'') (an importer of subject merchandise),...

  9. Miniaturized fracture tests for thin-walled tubular SiC specimens

    SciTech Connect

    Byun, Thak Sang; Lara-Curzio, Edgar; Lowden, Richard Andrew; Snead, Lance Lewis; Katoh, Yutai

    2007-01-01

    Two testing methods have been developed for miniaturized tubular specimens to evaluate the fracture stress of chemically vapor deposited (CVD) SiC coatings in nuclear fuel particles. In the first method hoop stress is applied to a thin-walled tubular specimen by internal pressurization using a polyurethane insert. The second method is a crushing technique, in which tubular specimen is fractured by diametrical compressive loading. Tubular SiC specimens with a wall thickness of about 100 {micro}m and inner diameters of about 0.9 mm (SiC-A) and 1 mm (SiC-B) were extracted from surrogate nuclear fuels and tested using the two test methods. Mean fracture stresses of 239, 263, and 283 MPa were measured for SiC-A and SiC-B by internal pressurization, and SiC-A by diametrical loading, respectively. In addition, size effects in the fracture stress were investigated using tubular alumina specimens with various sizes. A significant size effect was found in the experimental data and was also predicted by the effective area-based scaling method.

  10. Muscle imaging in patients with tubular aggregate myopathy caused by mutations in STIM1

    PubMed Central

    Tasca, Giorgio; D'Amico, Adele; Monforte, Mauro; Nadaj-Pakleza, Aleksandra; Vialle, Marc; Fattori, Fabiana; Vissing, John; Ricci, Enzo; Bertini, Enrico

    2015-01-01

    Tubular aggregate myopathy is a genetically heterogeneous disease characterized by tubular aggregates as the hallmark on muscle biopsy. Mutations in STIM1 have recently been identified as one genetic cause in a number of tubular aggregate myopathy cases. To characterize the pattern of muscle involvement in this disease, upper and lower girdles and lower limbs were imaged in five patients with mutations in STIM1, and the scans were compared with two patients with tubular aggregate myopathy not caused by mutations in STIM1. A common pattern of involvement was found in STIM1-mutated patients, although with variable extent and severity of lesions. In the upper girdle, the subscapularis muscle was invariably affected. In the lower limbs, all the patients showed a consistent involvement of the flexor hallucis longus, which is very rarely affected in other muscle diseases, and a diffuse involvement of thigh and posterior leg with sparing of gracilis, tibialis anterior and, to a lesser extent, short head of biceps femoris. Mutations in STIM1 are associated with a homogeneous involvement on imaging despite variable clinical features. Muscle imaging can be useful in identifying STIM1-mutated patients especially among other forms of tubular aggregate myopathy. PMID:26255678

  11. Polydopamine-coated open tubular column for the separation of proteins by capillary electrochromatography.

    PubMed

    Xiao, Xing; Wang, Wentao; Chen, Jia; Jia, Li

    2015-08-01

    The separation and determination of proteins in food is an important aspect in food industry. Inspired by the self-polymerization of dopamine under alkaline conditions and the natural adhesive properties of polydopamine, in this paper, a simple and economical method was developed for the preparation of polydopamine-coated open tubular column, in which ammonium persulfate was used as the source of oxygen to induce and facilitate the polymerization of dopamine to form polydopamine. In comparison with a naked fused-silica capillary, the direction and magnitude of the electro-osmotic flow of the as-prepared polydopamine-coated open tubular column could be manipulated by varying the pH values of background solutions due to the existence of amine and phenolic hydroxyl groups on polydopamine coating. The surface morphology of the polydopamine-coated open tubular column was studied by scanning electron microscopy, and the thickness of polydopamine coating was 106 nm. The performance of the polydopamine-coated open tubular column was validated by analysis of proteins. The relative standard deviations of migration times of proteins representing run-to-run, day-to-day, and column-to-column were less than 3.5%. In addition, the feasibility of the polydopamine-coated open tubular column for real samples was verified by the separation of proteins in chicken egg white and pure milk. PMID:26017540

  12. Muscle imaging in patients with tubular aggregate myopathy caused by mutations in STIM1.

    PubMed

    Tasca, Giorgio; D'Amico, Adele; Monforte, Mauro; Nadaj-Pakleza, Aleksandra; Vialle, Marc; Fattori, Fabiana; Vissing, John; Ricci, Enzo; Bertini, Enrico

    2015-11-01

    Tubular aggregate myopathy is a genetically heterogeneous disease characterized by tubular aggregates as the hallmark on muscle biopsy. Mutations in STIM1 have recently been identified as one genetic cause in a number of tubular aggregate myopathy cases. To characterize the pattern of muscle involvement in this disease, upper and lower girdles and lower limbs were imaged in five patients with mutations in STIM1, and the scans were compared with two patients with tubular aggregate myopathy not caused by mutations in STIM1. A common pattern of involvement was found in STIM1-mutated patients, although with variable extent and severity of lesions. In the upper girdle, the subscapularis muscle was invariably affected. In the lower limbs, all the patients showed a consistent involvement of the flexor hallucis longus, which is very rarely affected in other muscle diseases, and a diffuse involvement of thigh and posterior leg with sparing of gracilis, tibialis anterior and, to a lesser extent, short head of biceps femoris. Mutations in STIM1 are associated with a homogeneous involvement on imaging despite variable clinical features. Muscle imaging can be useful in identifying STIM1-mutated patients especially among other forms of tubular aggregate myopathy. PMID:26255678

  13. Cellular Uptake and Localization of Polymyxins in Renal Tubular Cells Using Rationally Designed Fluorescent Probes

    PubMed Central

    Yun, Bo; Azad, Mohammad A. K.; Nowell, Cameron J.; Nation, Roger L.; Thompson, Philip E.; Roberts, Kade D.

    2015-01-01

    Polymyxins are cyclic lipopeptide antibiotics that serve as a last line of defense against Gram-negative bacterial superbugs. However, the extensive accumulation of polymyxins in renal tubular cells can lead to nephrotoxicity, which is the major dose-limiting factor in clinical use. In order to gain further insights into the mechanism of polymyxin-induced nephrotoxicity, we have rationally designed novel fluorescent polymyxin probes to examine the localization of polymyxins in rat renal tubular (NRK-52E) cells. Our design strategy focused on incorporating a dansyl fluorophore at the hydrophobic centers of the polymyxin core structure. To this end, four novel regioselectively labeled monodansylated polymyxin B probes (MIPS-9541, MIPS-9542, MIPS-9543, and MIPS-9544) were designed, synthesized, and screened for their antimicrobial activities and apoptotic effects against rat kidney proximal tubular cells. On the basis of the assessment of antimicrobial activities, cellular uptake, and apoptotic effects on renal tubular cells, incorporation of a dansyl fluorophore at either position 6 or 7 (MIPS-9543 and MIPS-9544, respectively) of the polymyxin core structure appears to be an appropriate strategy for generating representative fluorescent polymyxin probes to be utilized in intracellular imaging and mechanistic studies. Furthermore, confocal imaging experiments utilizing these probes showed evidence of partial colocalization of the polymyxins with both the endoplasmic reticulum and mitochondria in rat renal tubular cells. Our results highlight the value of these new fluorescent polymyxin probes and provide further insights into the mechanism of polymyxin-induced nephrotoxicity. PMID:26392495

  14. p-Cresol mediates autophagic cell death in renal proximal tubular cells.

    PubMed

    Lin, Hsin-Hung; Huang, Chiu-Ching; Lin, Tze-Yi; Lin, Ching-Yuang

    2015-04-01

    Higher serum level of p-cresol (PC) in chronic kidney disease (CKD) patients has been linked with CKD progression. The toxic effect of PC on diverse cells has been reported by prior studies, except for renal tubular cells. Both autophagy and apoptosis contribute to renal tubular cell death, yet evidence of its response to PC is limited and their crosstalk is still unclear. Autophagy is an important cellular process involved in toxin-induced cell death. Renal tubular cell death in tubular injury is thought to be one of the key events causing the progression of CKD. Thus, we treated rat (NRK-52E) and human (HRPTEC) renal proximal tubular cells (RPTC) with PC and found the cell proliferation was significantly decreased. Cell apoptosis was significantly increased and accompanied with the activation of autophagy as evidenced by increases in LC3-II, beclin 1 and Atg 4. We also found an increase of p62 by c-Jun activation. p62 accumulation could mediate the activation of caspase 8-dependent cell apoptosis. Conversely, knockdown of p62 by siRNA of p62 had the opposite effect by arresting LC3-II accumulation and promoting increasing cell viability. We conclude that PC triggered autophagic RPTC death via JNK-mediated p62 accumulation and then activated caspase 8-dependent cell death pathway. PC can be considered as one of the key events causing progression of CKD, which might affect drug disposition in CKD cases. PMID:25668154

  15. Medullary nephrocalcinosis, distal renal tubular acidosis and polycythaemia in a patient with nephrotic syndrome

    PubMed Central

    2012-01-01

    Background Medullary nephrocalcinosis and distal renal tubular acidosis are closely associated and each can lead to the other. These clinical entities are rare in patients with nephrotic syndrome and polycythaemia is an unusual finding in such patients. We describe the presence of medullary nephrocalcinosis, distal renal tubular acidosis and polycythaemia in a patient with nephrotic syndrome due to minimal change disease. Proposed mechanisms of polycythaemia in patients with nephrotic syndrome and distal renal tubular acidosis include, increased erythropoietin production and secretion of interleukin 8 which in turn stimulate erythropoiesis. Case presentation A 22 year old Sri Lankan Sinhala male with nephrotic syndrome due to minimal change disease was investigated for incidentally detected polycythaemia. Investigations revealed the presence of renal tubular acidosis type I and medullary nephrocalcinosis. Despite extensive investigation, a definite cause for polycythaemia was not found in this patient. Treatment with potassium and bicarbonate supplementation with potassium citrate led to correction of acidosis thereby avoiding the progression of nephrocalcinosis and harmful effects of chronic acidosis. Conclusion The constellation of clinical and biochemical findings in this patient is unique but the pathogenesis of erythrocytosis is not clearly explained. The proposed mechanisms for erythrocytosis in other patients with proteinuria include increased erythropoietin secretion due to renal hypoxia and increased secretion of interleukin 8 from the kidney. This case illustrates that there may exist hitherto unknown connections between tubular and glomerular dysfunction in patients with nephrotic syndrome. PMID:22834973

  16. Tubular Tissues and Organs of Human Body--Challenges in Regenerative Medicine.

    PubMed

    Góra, Aleksander; Pliszka, Damian; Mukherjee, Shayanti; Ramakrishna, Seeram

    2016-01-01

    Tissue engineering of tubular organs such as the blood vessel, trachea gastrointestinal tract, urinary tract are of the great interest due to the high amount of surgeries performed annually on those organs. Development in tissue engineering in recent years and promising results, showed need to investigate more complex constructs that need to be designed in special manner. Stent technology remain the most widely used procedure to restore functions of tubular tissues after cancer treatment, or after organ removal due to traumatic accidents. Tubular structures like blood vessels, intestines, and trachea have to work in specific environment at the boundary of the liquids, solids or air and surrounding tissues and ensure suitable separation between them. This brings additional challenges in tissue engineering science in order to construct complete organs by using combinations of various cells along with the support material systems. Here we give a comprehensive review of the tubular structures of the human body, in perspective of the current methods of treatment and progress in regenerative medicine that aims to develop fully functioning organs of tubular shape. Extensive analysis of the available literature has been done focusing on materials and methods of creations of such organs. This work describes the attempts to incorporate growth factors and drugs within the scaffolds to ensure localized drug release and enhance vascularization of the organ by attracting blood vessels to the site of implantation. PMID:27398431

  17. Renal tubular dysfunction in patients with inflammatory bowel disease treated with aminosalicylate.

    PubMed Central

    Schreiber, S; Hämling, J; Zehnter, E; Howaldt, S; Daerr, W; Raedler, A; Kruis, W

    1997-01-01

    BACKGROUND: An increasing number of case reports indicate potential nephrotoxicity of 5-aminosalicylic acid (5-ASA), which shares similarities with the chemical structures of both phenacetin and acetylsalicylic acid. AIM: In a point prevalence study the occurrence of sensitive indices indicative of early kidney malfunction was assessed in outpatients with inflammatory bowel disease. METHODS: Routine indices of kidney function (creatinine clearance, urinary protein content, pH, electrolytes, and microscopy) were investigated in 223 patients with inflammatory bowel disease as well as sensitive markers of glomerular or tubular dysfunction (microproteinuria by SDS polyacrylamide gel electrophoresis (SDS-PAGE), urinary concentrations of N-acetyl-beta-D-glucosaminidase, alpha 1-microglobulin, gamma-glutamyltransferase (GGT), alkaline phosphatase (AP), and albumin). Histories of exposure to 5-ASA were assessed by questionnaire. RESULTS: Patients receiving high amounts of 5-ASA, both actual as well as on a lifetime basis, showed an increased prevalence of tubular proteinuria by SDS-PAGE. Raised values for urinary AP and GGT indicate proximal tubular epithelial cells as the source. All other kidney function tests were normal. Analysis of covariates indicated strong associations between disease activity and size of 5-ASA doses as well as alterations in kidney tubular function. CONCLUSION: The possibility exists that high doses of 5-ASA may be associated with proximal tubular proteinuria. This point prevalence study cannot dissect the possible impact of chronic inflammation from high dose 5-ASA treatment and further prospective studies are warranted. PMID:9245930

  18. CD47 regulates renal tubular epithelial cell self-renewal and proliferation following renal ischemia reperfusion.

    PubMed

    Rogers, Natasha M; Zhang, Zheng J; Wang, Jiao-Jing; Thomson, Angus W; Isenberg, Jeffrey S

    2016-08-01

    Defects in renal tubular epithelial cell repair contribute to renal ischemia reperfusion injury, cause acute kidney damage, and promote chronic renal disease. The matricellular protein thrombospondin-1 and its receptor CD47 are involved in experimental renal ischemia reperfusion injury, although the role of this interaction in renal recovery is unknown. We found upregulation of self-renewal genes (transcription factors Oct4, Sox2, Klf4 and cMyc) in the kidney of CD47(-/-) mice after ischemia reperfusion injury. Wild-type animals had minimal self-renewal gene expression, both before and after injury. Suggestive of cell autonomy, CD47(-/-) renal tubular epithelial cells were found to increase expression of the self-renewal genes. This correlated with enhanced proliferative capacity compared with cells from wild-type mice. Exogenous thrombospondin-1 inhibited self-renewal gene expression in renal tubular epithelial cells from wild-type but not CD47(-/-) mice, and this was associated with decreased proliferation. Treatment of renal tubular epithelial cells with a CD47 blocking antibody or CD47-targeting small interfering RNA increased expression of some self-renewal transcription factors and promoted cell proliferation. In a syngeneic kidney transplant model, treatment with a CD47 blocking antibody increased self-renewal transcription factor expression, decreased tissue damage, and improved renal function compared with that in control mice. Thus, thrombospondin-1 via CD47 inhibits renal tubular epithelial cell recovery after ischemia reperfusion injury through inhibition of proliferation/self-renewal. PMID:27259369

  19. Alpha detection in pipes using an inverting membrane scintillator

    SciTech Connect

    Kendrick, D.T.; Cremer, C.D.; Lowry, W.

    1995-10-01

    Characterization of surface alpha emitting contamination inside enclosed spaces such as piping systems presents an interesting radiological measurement challenge. Detection of these alpha particles from the exterior of the pipe is impossible since the alpha particles are completely absorbed by the pipe wall. Traditional survey techniques, using hand-held instruments, simply can not be used effectively inside pipes. Science and Engineering Associates, Inc. is currently developing an enhancement to its Pipe Explorer{trademark} system that will address this challenge. The Pipe Explorer{trademark} uses a unique sensor deployment method where an inverted tubular membrane is propagated through complex pipe runs via air pressure. The inversion process causes the membrane to fold out against the pipe wall, such that no part of the membrane drags along the pipe wall. This deployment methodology has been successfully demonstrated at several DOE sites to transport specially designed beta and gamma, scintillation detectors into pipes ranging in length up to 250 ft.

  20. Osteomalacia complicating renal tubular acidosis in association with Sjogren's syndrome.

    PubMed

    El Ati, Zohra; Fatma, Lilia Ben; Boulahya, Ghada; Rais, Lamia; Krid, Madiha; Smaoui, Wided; Maiz, Hedi Ben; Beji, Soumaya; Zouaghi, Karim; Moussa, Fatma Ben

    2014-09-01

    Renal involvement in Sjogren's syndrome (SS) is not uncommon and may precede other complaints. Tubulointerstitial nephritis is the most common renal disease in SS and may lead to renal tubular acidosis (RTA), which in turn may cause osteomalacia. Nevertheless, osteomalacia rarely occurs as the first manifestation of a renal tubule disorder due to SS. We herewith describe a 43-year-old woman who was admitted to our hospital for weakness, lumbago and inability to walk. X-ray of the long bones showed extensive demineralization of the bones. Laboratory investigations revealed chronic kidney disease with serum creatinine of 2.3 mg/dL and creatinine clearance of 40 mL/min, hypokalemia (3.2 mmol/L), hypophosphatemia (0.4 mmol/L), hypocalcemia (2.14 mmol/L) and hyperchloremic metabolic acidosis (chlorine: 114 mmol/L; alkaline reserve: 14 mmol/L). The serum alkaline phosphatase levels were elevated. The serum levels of 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D were low and borderline low, respectively, and the parathyroid hormone level was 70 pg/L. Urinalysis showed inappropriate alkaline urine (urinary PH: 7), glycosuria with normal blood glucose, phosphaturia and uricosuria. These values indicated the presence of both distal and proximal RTA. Our patient reported dryness of the mouth and eyes and Schirmer's test showed xerophthalmia. An accessory salivary gland biopsy showed changes corresponding to stage IV of Chisholm and Masson score. Kidney biopsy showed diffuse and severe tubulo-interstitial nephritis with dense lymphoplasmocyte infiltrates. Sicca syndrome and renal interstitial infiltrates indicated SS as the underlying cause of the RTA and osteomalacia. The patient received alkalinization, vitamin D (Sterogyl ®), calcium supplements and steroids in an initial dose of 1 mg/kg/day, tapered to 10 mg daily. The prognosis was favorable and the serum creatinine level was 1.7 mg/dL, calcium was 2.2 mmol/L and serum phosphate was 0.9 mmol/L. PMID:25193912

  1. Human anion exchanger1 mutations and distal renal tubular acidosis.

    PubMed

    Yenchitsomanus, Pa-thai

    2003-09-01

    The human anion exchanger 1 (AE1 or SLC4A1) gene encodes anion exchanger 1 (or band 3) protein in erythrocytes and in alpha-intercalated cells of the kidney. Thus, AE1 mutations show pleiotrophic effects resulting in two distinct and seemingly unrelated defects, an erythrocyte abnormality and distal renal tubular acidosis (dRTA). Southeast Asian ovalocytosis (SAO), a well-known red blood cell (RBC) defect, which is widespread in Southeast Asian regions, is caused by AE1 mutation due to a deletion of 27 base pairs in codons 400-408 (delta400-408) leading to an in-frame 9 amino-acid loss in the protein. Co-existence of SAO and dRTA is usually not seen in the same individual. However, the two conditions can co-exist as the result of compound heterozygosities between delta400-408 and other mutations. The reported genotypes include delta400-408/G701D, delta400-408/R602H, delta400-408/deltaV850, and delta400-408/A858D. The presence of dRTA, with or without RBC abnormalities, may occur from homozygous or compound heterozygous conditions of recessive AE1 mutations (eg G701D/G701D, V488M/V488M, deltaV850/deltaV850, deltaV850/A858D, G701D/S773P) or heterozygous dominant AE1 mutations (eg R598H, R589C, R589S, S613F, R901X). Codon 589 of this gene seems to be a 'mutational hot-spot' since repeated mutations at this codon occurring in different ethnic groups and at least two de novo (R589H and R589C) mutations have been observed. Therefore, AE1 mutations can result in both recessive and dominant dRTA, possibly depending on the position of the amino acid change in the protein. As several mutant AE1 proteins still maintain a significant anion transport function but are defective in targeting to the cell surface, impaired intracellular trafficking of the mutant AE1 is an important molecular mechanism involved in the pathogenesis of dRTA associated with AE1 mutations. PMID:15115146

  2. [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

  3. Enhanced ionic oxygen flow through mixed ionic-electronic conducting membranes: Directional dependence, composite construction and the partial oxidation of methane

    NASA Astrophysics Data System (ADS)

    Gerdes, Kirk R.

    Mixed Ionic-Electronic Conducting (MIEC) membranes transport ions and electrons in a crystalline matrix. Ionic transport occurs through MIEC materials in the presence of an applied ionic potential gradient. MIEC membranes form a special class of ionic conductors with primary applications as membrane separators, sensors, and components in solid oxide fuel cells. Current efforts focus on separation of oxygen from air for supply to high temperature reactions. One such reaction is the methane partial oxidation to synthesis gas (CO and H2). Certain MIEC membrane characteristics are required for a methane partial oxidation reactor: (1) the cost of the material must be economical on a tube cost per mol oxygen transported basis; (2) the membrane must be stable in steep oxygen partial pressure gradients and in the presence of reducing gases; (3) the membrane must be stable at temperatures exceeding 800°C without fracturing due to thermal stress. Two mechanisms govern the transport of oxygen through MIEC membranes: surface exchange at the MIEC/gas surface and ionic transport through the MIEC bulk. Most MIEC membranes conduct oxygen with a mixed transport mechanism, i.e., both surface exchange and bulk diffusion affect the total transport. We investigate the relative importance of bulk diffusion versus surface exchange in MIEC tubular and disk membranes made of La0.5Sr0.5Fe 0.8Ga0.2O3-delta. We propose a proof based on the currently accepted transport model for the directional dependence of ionic flow through a tubular MIEC. We qualitatively confirm directional dependence using a novel experimental system. Further, we propose a model for ionic flow in a composite membrane system consisting of a dense, tubular LSFG substrate with a thin, dense layer of SrCox Fe1-xO3-delta applied to the surface(s). Comparisons are made between the performance of the monolithic membrane tube and the layered composite membrane tube. A layered composite tubular membrane is constructed and tested

  4. Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

    PubMed Central

    Chea, Vorleak; Paolucci-Jeanjean, Delphine; Sanchez, José; Belleville, Marie-Pierre

    2014-01-01

    This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR). The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP) was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP) to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1), consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2), whereas at the highest substrate concentration (500 mg·L−1), it was shown that the reaction was limited by the oxygen content. PMID:25295628

  5. Dynamic sorting of lipids and proteins in membrane tubes with a moving phase boundary

    PubMed Central

    Heinrich, Michael; Tian, Aiwei; Esposito, Cinzia; Baumgart, Tobias

    2010-01-01

    Cellular organelle membranes maintain their integrity, global shape, and composition despite vigorous exchange among compartments of lipids and proteins during trafficking and signaling. Organelle homeostasis involves dynamic molecular sorting mechanisms that are far from being understood. In contrast, equilibrium thermodynamics of membrane mixing and sorting, particularly the phase behavior of binary and ternary model membrane mixtures and its coupling to membrane mechanics, is relatively well characterized. Elucidating the continuous turnover of live cell membranes, however, calls for experimental and theoretical membrane models enabling manipulation and investigation of directional mass transport. Here we introduce the phenomenon of curvature-induced domain nucleation and growth in membrane mixtures with fluid phase coexistence. Membrane domains were consistently observed to nucleate precisely at the junction between a strongly curved cylindrical (tube) membrane and a pipette-aspirated giant unilamellar vesicle. This experimental geometry mimics intracellular sorting compartments, because they often show tubular-vesicular membrane regions. Nucleated domains at tube necks were observed to present diffusion barriers to the transport of lipids and proteins. We find that curvature-nucleated domains grow with characteristic parabolic time dependence that is strongly curvature-dependent. We derive an analytical model that reflects the observed growth dynamics. Numerically calculated membrane shapes furthermore allow us to elucidate mechanical details underlying curvature-dependent directed lipid transport. Our observations suggest a novel dynamic membrane sorting principle that may contribute to intracellular protein and lipid sorting and trafficking. PMID:20368457

  6. Characterization of the equine blood-testis barrier during tubular development in normal and cryptorchid stallions.

    PubMed

    Rode, K; Sieme, H; Richterich, P; Brehm, R

    2015-09-15

    The formation of the blood-testis barrier (BTB) is defined as occurring with the first appearance of spermatocytes at around puberty and is vital for normal spermatogenesis. This barrier between two adjacent Sertoli cells (SCs) consists of a cell junctional protein complex, which includes tight junctions (TJs), adherens junctions, and gap junctions. In many mammalian species, BTB composition has already been investigated, whereas little is known about the equine BTB. In the present study, immunohistochemistry and qualitative Western Blot analysis were used to assess the expression and distribution patterns of the junctional proteins claudin-11 (TJ), zonula occludens-1 (TJ associated), N-cadherin (adherens junctions), and connexin 43 (gap junctions) in equine testes during tubular development and in testes of stallions exhibiting unilateral cryptorchidism. Therefore, testes of 21 warmblood stallions (aged 12 months-11 years) were obtained during routine surgical castration. In the normal adult equine testis, the junctional proteins are localized at the basolateral region of the seminiferous tubules forming a circumferential seal corresponding to the known BTB localization. N-cadherin is additionally expressed along the lateral SC surface. In immature seminiferous cords still lacking a lumen, a diffuse distribution pattern of the junctional proteins throughout the SC cytoplasm is visible. As lumen formation advances, the immunolocalization shifts progressively toward the basolateral SC membranes. Additionally, apoptotic germ cells were detected and quantified in prepubertal stallions using terminal deoxynucleotidyl transferase dUTP nick end labeling assay and correlated with junctional protein localization. In the retained testis of cryptorchid stallions, which exhibit an aberrant testicular morphology, a deviating expression of the junctional proteins is visible. The present data show for the first time that (1) the equine SC junctional complex contains claudin-11

  7. Cis and trans interactions between atlastin molecules during membrane fusion

    PubMed Central

    Liu, Tina Y.; Bian, Xin; Romano, Fabian B.; Shemesh, Tom; Rapoport, Tom A.; Hu, Junjie

    2015-01-01

    Atlastin (ATL), a membrane-anchored GTPase that mediates homotypic fusion of endoplasmic reticulum (ER) membranes, is required for formation of the tubular network of the peripheral ER. How exactly ATL mediates membrane fusion is only poorly understood. Here we show that fusion is preceded by the transient tethering of ATL-containing vesicles caused by the dimerization of ATL molecules in opposing membranes. Tethering requires GTP hydrolysis, not just GTP binding, because the two ATL molecules are pulled together most strongly in the transition state of GTP hydrolysis. Most tethering events are futile, so that multiple rounds of GTP hydrolysis are required for successful fusion. Supported lipid bilayer experiments show that ATL molecules sitting on the same (cis) membrane can also undergo nucleotide-dependent dimerization. These results suggest that GTP hydrolysis is required to dissociate cis dimers, generating a pool of ATL monomers that can dimerize with molecules on a different (trans) membrane. In addition, tethering and fusion require the cooperation of multiple ATL molecules in each membrane. We propose a comprehensive model for ATL-mediated fusion that takes into account futile tethering and competition between cis and trans interactions. PMID:25825753

  8. Oxygen Transport Membranes

    SciTech Connect

    S. Bandopadhyay

    2008-08-30

    small polaron conduction mechanism. Scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) were used to develop strategies to detect and characterize vacancy creation, dopant segregations and defect association in the oxygen conducting membrane material. The pO{sub 2} and temperature dependence of the conductivity, non-stoichiometry and thermal-expansion behavior of compositions with increasing complexity of substitution on the perovskite A and B sites were studied. Studies with the perovskite structure show anomalous behavior at low oxygen partial pressures (<10{sup -5} atm). The anomalies are due to non-equilibrium effects and can be avoided by using very strict criteria for the attainment of equilibrium. The slowness of the oxygen equilibration kinetics arises from two different mechanisms. In the first, a two phase region occurs between an oxygen vacancy ordered phase such as brownmillerite SrFeO{sub 2.5} and perovskite SrFeO{sub 3-x}. The slow kinetics is associated with crossing the two phase region. The width of the miscibility gap decreases with increasing temperature and consequently the effect is less pronounced at higher temperature. The preferred kinetic pathway to reduction of perovskite ferrites when the vacancy concentration corresponds to the formation of significant concentrations of Fe{sup 2+} is via the formation of a Ruddlesden-Popper (RP) phases as clearly observed in the case of La{sub 0.5}Sr{sub 0.5}FeO{sub 3-x} where LaSrFeO{sub 4} is found together with Fe. In more complex compositions, such as LSFTO, iron or iron rich phases are observed locally with no evidence for the presence of discrete RP phase. Fracture strength of tubular perovskite membranes was determined in air and in reducing atmospheric conditions. The strength of the membrane decreased with temperature and severity of reducing conditions although the strength distribution (Weibull parameter, m) was relatively unaltered. Surface and volume

  9. Cell-mediated Immunity to Human Tamm-Horsfall Glycoprotein in Autoimmune Liver Disease with Renal Tubular Acidosis

    PubMed Central

    Tsantoulas, D. C.; McFarlane, I. G.; Portmann, B.; Eddleston, A. L. W. F.; Williams, Roger

    1974-01-01

    Cell-mediated immune responses to Tamm-Horsfall glycoprotein isolated from human urine were investigated using the leucocyte migration test. Abnormal responses were found in 91% of patients with active chronic hepatitis or primary biliary cirrhosis with an associated renal tubular acidosis (R.T.A.) but in only 19% of those without R.T.A. In nearly all of a group of patients without autoimmune liver disease and in a control group of normal subjects results were within normal limits. In addition, using an immunofluorescent technique with rabbit antibody to human Tamm-Horsfall glycoprotein, it was possible to show the presence in human liver cell membrane of material reacting immunologically as Tamm-Horsfall. These findings suggest that the development of an immune response to this glycoprotein, initiated by release of cross-reacting antigens from damaged hepatocytes, could be the mechanism underlying the occurrence of R.T.A. in some patients with autoimmune liver disease. ImagesFIG. 3 PMID:4611578

  10. Renal tubular receptor imaging with iodine-131-labeled peanut lectin: pharmacokinetics and renal clearance mechanism in animals

    SciTech Connect

    Boniface, G.R.; Suresh, M.R.; Willans, D.J.; Tam, Y.K.; Shysh, A.; Longenecker, B.M.; Noujaim, A.A.

    1986-05-01

    Intravenously administered peanut lectin (PNA), iodinated with /sup 131/I ((/sup 131/I)PNA), is rapidly cleared from the plasma by the kidneys in dogs (clearance (total body) = 17.52 +/- 8.74 ml/min). Dynamic gamma camera renal scintigraphy demonstrated renal accumulation and excretion phases of the (/sup 131/I)PNA renogram in dogs and rabbits (% injection dose-at-peak = 21.8 +/- 3.3% and 19.6 +/- 4.3%, time-to-peak = 44.6 +/- 4.8 min and 37.2 +/- 6.9 min, respectively). Immunoperoxidase staining of kidney sections, following i.v. administered PNA, demonstrated predominant accumulation by the proximal tubules of mice, rabbits, and dogs. The basement membrane was intensely stained at early times p.i. while intracellular and luminal PNA was evident within 1 hr. Urine analysis confirmed the presence of intact (/sup 131/I)PNA in the bladder contents, while protein degradation products, and a small percentage of the free iodide (less than 5%) were noted within 1 hr p.i. The relative proportion of free iodide increased at later times p.i. (greater than 6 hr). A receptor mediated excretion mechanism is proposed for the clearance of PNA and may be useful for the study of renal tubular function.

  11. GRAF1 forms a complex with MICAL-L1 and EHD1 to cooperate in tubular recycling endosome vesiculation

    PubMed Central

    Cai, Bishuang; Xie, Shuwei; Caplan, Steve; Naslavsky, Naava

    2014-01-01

    The biogenesis of tubular recycling endosomes (TREs) and their subsequent vesiculation after cargo-sorting has occurred, is essential for receptor and lipid recycling to the plasma membrane. Although recent studies have implicated the C-terminal Eps15 Homology Domain (EHD) protein, EHD1, as a key regulator of TRE vesiculation, additional proteins involved in this process have been largely uncharacterized. In the present study, we identify the GTPase Regulator Associated with Focal adhesion kinase-1 (GRAF1) protein in a complex with EHD1 and the TRE hub protein, Molecules Interacting with CasL-Like1 (MICAL-L1). Over-expression of GRAF1 caused vesiculation of MICAL-L1-containing TRE, whereas GRAF1-depletion led to impaired TRE vesiculation and delayed receptor recycling. Moreover, co-addition of purified EHD1 and GRAF1 in a semi-permeabilized cell vesiculation assay produced synergistic TRE vesiculation. Overall, based on our data, we suggest that in addition to its roles in clathrin-independent endocytosis, GRAF1 synergizes with EHD1 to support TRE vesiculation. PMID:25364729

  12. Novel AE1 mutations in recessive distal renal tubular acidosis. Loss-of-function is rescued by glycophorin A.

    PubMed

    Tanphaichitr, V S; Sumboonnanonda, A; Ideguchi, H; Shayakul, C; Brugnara, C; Takao, M; Veerakul, G; Alper, S L

    1998-12-15

    The AE1 gene encodes band 3 Cl-/HCO3- exchangers that are expressed both in the erythrocyte and in the acid-secreting, type A intercalated cells of the kidney. Kidney AE1 contributes to urinary acidification by providing the major exit route for HCO3- across the basolateral membrane. Several AE1 mutations cosegregate with dominantly transmitted nonsyndromic renal tubular acidosis (dRTA). However, the modest degree of in vitro hypofunction exhibited by these dRTA-associated mutations fails to explain the disease phenotype in light of the normal urinary acidification associated with the complete loss-of-function exhibited by AE1 mutations linked to dominant spherocytosis. We report here novel AE1 mutations linked to a recessive syndrome of dRTA and hemolytic anemia in which red cell anion transport is normal. Both affected individuals were triply homozygous for two benign mutations M31T and K56E and for the loss-of-function mutation, G701D. AE1 G701D loss-of-function was accompanied by impaired trafficking to the Xenopus oocyte surface. Coexpression with AE1 G701D of the erythroid AE1 chaperonin, glycophorin A, rescued both AE1-mediated Cl- transport and AE1 surface expression in oocytes. The genetic and functional data both suggest that the homozygous AE1 G701D mutation causes recessively transmitted dRTA in this kindred with apparently normal erythroid anion transport. PMID:9854053

  13. Status report on the development of a tubular electron beam ion source

    NASA Astrophysics Data System (ADS)

    Donets, E. D.; Donets, E. E.; Becker, R.; Liljeby, L.; Rensfelt, K.-G.; Beebe, E. N.; Pikin, A. I.

    2004-05-01

    The theoretical estimations and numerical simulations of tubular electron beams in both beam and reflex mode of source operation as well as the off-axis ion extraction from a tubular electron beam ion source (TEBIS) are presented. Numerical simulations have been done with the use of the IGUN and OPERA-3D codes. Numerical simulations with IGUN code show that the effective electron current can reach more than 100 A with a beam current density of about 300-400 A/cm2 and the electron energy in the region of several KeV with a corresponding increase of the ion output. Off-axis ion extraction from the TEBIS, being the nonaxially symmetric problem, was simulated with OPERA-3D (SCALA) code. The conceptual design and main parameters of new tubular sources which are under consideration at JINR, MSL, and BNL are based on these simulations.

  14. Species Diversity Regarding the Presence of Proximal Tubular Progenitor Cells of the Kidney

    PubMed Central

    Hansson, J.; Ericsson, A.E.; Axelson, H.; Johansson, M.E.

    2016-01-01

    The cellular source for tubular regeneration following kidney injury is a matter of dispute, with reports suggesting a stem or progenitor cells as the regeneration source while linage tracing studies in mice seemingly favor the classical theory, where regeneration is performed by randomly surviving cells. We, and others have previously described a scattered cell population localized to the tubules of human kidney, which increases in number following injury. Here we have characterized the species distribution of these proximal tubular progenitor cells (PTPCs) in kidney tissue from chimpanzee, pig, rat and mouse using a set of human PTPC markers. We detected PTPCs in chimpanzee and pig kidneys, but not in mouse tissue. Also, subjecting mice to the unilateral urethral obstruction model, caused clear signs of tubular injury, but failed to induce the PTPC phenotype in renal tubules. PMID:26972712

  15. Thermal sprayed composite melt containment tubular component and method of making same

    DOEpatents

    Besser, Matthew F.; Terpstra, Robert L.; Sordelet, Daniel J.; Anderson, Iver E.

    2002-03-19

    A tubular thermal sprayed melt containment component for transient containment of molten metal or alloy wherein the tubular member includes a thermal sprayed inner melt-contacting layer for contacting molten metal or alloy to be processed, a thermal sprayed heat-generating layer deposited on the inner layer, and an optional thermal sprayed outer thermal insulating layer. The thermal sprayed heat-generating layer is inductively heated as a susceptor of an induction field or electrical resistively heated by passing electrical current therethrough. The tubular thermal sprayed melt containment component can comprise an elongated melt pour tube of a gas atomization apparatus where the melt pour tube supplies molten material from a crucible to an underlying melt atomization nozzle.

  16. Population analysis of the cingulum bundle using the tubular surface model for schizophrenia detection

    NASA Astrophysics Data System (ADS)

    Mohan, Vandana; Sundaramoorthi, Ganesh; Kubicki, Marek; Terry, Douglas; Tannenbaum, Allen

    2010-03-01

    We propose a novel framework for population analysis of DW-MRI data using the Tubular Surface Model. We focus on the Cingulum Bundle (CB) - a major tract for the Limbic System and the main connection of the Cingulate Gyrus, which has been associated with several aspects of Schizophrenia symptomatology. The Tubular Surface Model represents a tubular surface as a center-line with an associated radius function. It provides a natural way to sample statistics along the length of the fiber bundle and reduces the registration of fiber bundle surfaces to that of 4D curves. We apply our framework to a population of 20 subjects (10 normal, 10 schizophrenic) and obtain excellent results with neural network based classification (90% sensitivity, 95% specificity) as well as unsupervised clustering (k-means). Further, we apply statistical analysis to the feature data and characterize the discrimination ability of local regions of the CB, as a step towards localizing CB regions most relevant to Schizophrenia.

  17. Extinction and near-extinction instability of non-premixed tubular flames

    SciTech Connect

    Hu, Shengteng; Pitz, Robert W.; Yu, Wang

    2009-01-15

    Tubular non-premixed flames are formed by an opposed tubular burner, a new tool to study the effects of curvature on extinction and flame instability of non-premixed flames. Extinction of the opposed tubular flames generated by burning diluted H{sub 2}, CH{sub 4} or C{sub 3}H{sub 8} with air is investigated for both concave and convex curvature. To examine the effects of curvature on extinction, the critical fuel dilution ratios at extinction are measured at various stretch rates, initial mixture strengths and flame curvature for fuels diluted in N{sub 2}, He, Ar or CO{sub 2}. In addition, the onset conditions of the cellular instability are mapped as a function of stretch rates, initial mixture strengths, and flame curvature. For fuel mixtures with Lewis numbers much less than unity, such as H{sub 2}/N{sub 2}, concave flame curvature towards the fuel suppresses cellular instabilities. (author)

  18. Energetics and electronic structure of tubular Si vacancies filled with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kochi, Taketo; Okada, Susumu

    2016-05-01

    We studied the energetics and electronic structure of tubular Si vacancies incorporating a carbon nanotube (CNT), using first-principles total-energy calculations based on the density functional theory. Our calculations show that the incorporated CNT into a Si nanotunnel acts as an atom-thickness liner providing the electrostatically flat nanoscale space inside them by shielding the dangling bond states of tubular Si vacancies. The incorporation of the CNT into the tubular Si vacancies is exothermic with an energy gain up to 7.4 eV/nm depending on the diameters of the vacancy and encapsulated CNT. The electronic states of the vacancy substantially hybridize with those of the CNT, leading to the complex electronic energy band near the Fermi level.

  19. Influence of venting areas on the air blast pressure inside tubular structures like railway carriages.

    PubMed

    Larcher, Martin; Casadei, Folco; Solomos, George

    2010-11-15

    In case of a terrorist bomb attack the influence and efficiency of venting areas in tubular structures like train carriages is of interest. The pressure-time function of an air blast wave resulting from a solid charge is first compared to that of a gas or dust explosion and the capability of a venting structure to fly away is assessed. Several calculations using fluid-structure interaction are performed, which show that after a certain distance from the explosion, the air blast wave inside a tubular structure becomes one-dimensional, and that the influence of venting areas parallel to the wave propagation direction is small. The pressure peak and the impulse at certain points in a tubular structure are compared for several opening sizes. The overall influence of realistic size venting devices remains moderate and their usefulness in mitigating internal explosion effects in trains is discussed. PMID:20728991

  20. Exercise-induced cramp, myoglobinuria, and tubular aggregates in phosphoglycerate mutase deficiency.

    PubMed

    Oh, Shin J; Park, Kyung-Seok; Ryan, Hewitt F; Danon, Moris J; Lu, Jiesheng; Naini, Ali B; DiMauro, Salvatore

    2006-11-01

    We report two patients in whom phosphoglycerate mutase (PGAM) deficiency was associated with the triad of exercise-induced cramps, recurrent myoglobinuria, and tubular aggregates in the muscle biopsy. Serum creatine kinase (CK) levels were elevated between attacks of myoglobinuria. Forearm ischemic exercise tests produced subnormal increases of venous lactate. Muscle biopsies showed subsarcolemmal tubular aggregates in type 2 fibers. Muscle PGAM activities were markedly decreased (3% of the normal mean) and molecular genetic studies showed that both patients were homozygous for a described missense mutation (W78X). A review of 15 cases with tubular aggregates in the muscle biopsies from our laboratory and 15 cases with PGAM deficiency described in the literature showed that this clinicopathological triad is highly suggestive of PGAM deficiency. PMID:16881065