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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 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

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  4. Fluorescence detection of trace PCB101 based on PITC immobilized on porous AAO membrane.

    PubMed

    Wang, Meiling; Meng, Guowen; Huang, Qing; Li, Mingtao; Li, Zhongbo; Tang, Chaolong

    2011-01-21

    A sensitive and selective fluorescent membrane for rapid detection of trace 2,2',4,5,5'-pentachlorinated biphenyl (PCB101) has been achieved by immobilizing the fluorophore phenyl isothiocyanate (PITC) onto porous anodic aluminium oxide (AAO) membrane (denoted as PITC@AAO). The fluorescence of the PITC@AAO membrane is obviously enhanced after titrating the analyte PCB101 into the membrane, being ascribed to the halogen-bonding interaction between the fluorophore PITC and the analyte PCB101. The fluorescence intensity increases with the PCB101 concentration in the low range below 1 ppm, and there exists an approximate linear relationship between the relative fluorescence intensity and the PCB101 concentration in the low range of 1-6 ppb. Moreover, the PITC@AAO membrane shows good selectivity; for example, it is insensitive to common structural analogs (polychlorinated aromatics). The mechanisms of the fluorescence enhancement and the better sensitivity and selectivity of the PITC@AAO membrane to PCB101 than that of PITC/n-hexane solution are also discussed. This work demonstrates that trace (in ppb range) PCBs can be detected by simple fluorescence measurement.

  5. 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.

  6. 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.

  7. 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.

  8. Tubular membrane bioreactors for biotechnological processes.

    PubMed

    Wolff, Christoph; Beutel, Sascha; Scheper, Thomas

    2013-02-01

    This article is an overview of bioreactors using tubular membranes such as hollow fibers or ceramic capillaries for cultivation processes. This diverse group of bioreactor is described here in regard to the membrane materials used, operational modes, and configurations. The typical advantages of this kind of system such as environments with low shear stress together with high cell densities and also disadvantages like poor oxygen supply are summed up. As the usage of tubular membrane bioreactors is not restricted to a certain organism, a brief overview of various applications covering nearly all types of cells from prokaryotic to eukaryotic cells is also given here.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. A tunable sub-100 nm silicon nanopore array with an AAO membrane mask: reducing unwanted surface etching by introducing a PMMA interlayer.

    PubMed

    Lim, Namsoo; Pak, Yusin; Kim, Jin Tae; Hwang, Youngkyu; Lee, Ryeri; Kumaresan, Yogeenth; Myoung, NoSoung; Ko, Heung Cho; Jung, Gun Young

    2015-08-28

    Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array.

  14. 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}

  15. Lateral Diffusion on Tubular Membranes: Quantification of Measurements Bias

    PubMed Central

    Sandrin, Fanny; Izeddin, Ignacio; Bassereau, Patricia; Triller, Antoine

    2011-01-01

    Single Particle Tracking (SPT) is a powerful technique for the analysis of the lateral diffusion of the lipid and protein components of biological membranes. In neurons, SPT allows the study of the real-time dynamics of receptors for neurotransmitters that diffuse continuously in and out synapses. In the simplest case where the membrane is flat and is parallel to the focal plane of the microscope the analysis of diffusion from SPT data is relatively straightforward. However, in most biological samples the membranes are curved, which complicates analysis and may lead to erroneous conclusions as for the mode of lateral diffusion. Here we considered the case of lateral diffusion in tubular membranes, such as axons, dendrites or the neck of dendritic spines. Monte Carlo simulations allowed us to evaluate the error in diffusion coefficient (D) calculation if the curvature is not taken into account. The underestimation is determined by the diameter of the tubular surface, the frequency of image acquisition and the degree of mobility itself. We found that projected trajectories give estimates that are 25 to 50% lower than the real D in case of 2D-SPT over the tubular surface. The use of 3D-SPT improved the measurements if the frequency of image acquisition was fast enough in relation to the mobility of the molecules and the diameter of the tube. Nevertheless, the calculation of D from the components of displacements in the axis of the tubular structure gave accurate estimate of D, free of geometrical artefacts. We show the application of this approach to analyze the diffusion of a lipid on model tubular membranes and of a membrane-bound GFP on neurites from cultured rat hippocampal neurons. PMID:21980531

  16. Lateral diffusion on tubular membranes: quantification of measurements bias.

    PubMed

    Renner, Marianne; Domanov, Yegor; Sandrin, Fanny; Izeddin, Ignacio; Bassereau, Patricia; Triller, Antoine

    2011-01-01

    Single Particle Tracking (SPT) is a powerful technique for the analysis of the lateral diffusion of the lipid and protein components of biological membranes. In neurons, SPT allows the study of the real-time dynamics of receptors for neurotransmitters that diffuse continuously in and out synapses. In the simplest case where the membrane is flat and is parallel to the focal plane of the microscope the analysis of diffusion from SPT data is relatively straightforward. However, in most biological samples the membranes are curved, which complicates analysis and may lead to erroneous conclusions as for the mode of lateral diffusion. Here we considered the case of lateral diffusion in tubular membranes, such as axons, dendrites or the neck of dendritic spines. Monte Carlo simulations allowed us to evaluate the error in diffusion coefficient (D) calculation if the curvature is not taken into account. The underestimation is determined by the diameter of the tubular surface, the frequency of image acquisition and the degree of mobility itself. We found that projected trajectories give estimates that are 25 to 50% lower than the real D in case of 2D-SPT over the tubular surface. The use of 3D-SPT improved the measurements if the frequency of image acquisition was fast enough in relation to the mobility of the molecules and the diameter of the tube. Nevertheless, the calculation of D from the components of displacements in the axis of the tubular structure gave accurate estimate of D, free of geometrical artefacts. We show the application of this approach to analyze the diffusion of a lipid on model tubular membranes and of a membrane-bound GFP on neurites from cultured rat hippocampal neurons.

  17. 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.

  18. Friction Mediates Scission of Tubular Membranes Scaffolded by BAR Proteins.

    PubMed

    Simunovic, Mijo; Manneville, Jean-Baptiste; Renard, Henri-François; Evergren, Emma; Raghunathan, Krishnan; Bhatia, Dhiraj; Kenworthy, Anne K; Voth, Gregory A; Prost, Jacques; McMahon, Harvey T; Johannes, Ludger; Bassereau, Patricia; Callan-Jones, Andrew

    2017-06-29

    Membrane scission is essential for intracellular trafficking. While BAR domain proteins such as endophilin have been reported in dynamin-independent scission of tubular membrane necks, the cutting mechanism has yet to be deciphered. Here, we combine a theoretical model, in vitro, and in vivo experiments revealing how protein scaffolds may cut tubular membranes. We demonstrate that the protein scaffold bound to the underlying tube creates a frictional barrier for lipid diffusion; tube elongation thus builds local membrane tension until the membrane undergoes scission through lysis. We call this mechanism friction-driven scission (FDS). In cells, motors pull tubes, particularly during endocytosis. Through reconstitution, we show that motors not only can pull out and extend protein-scaffolded tubes but also can cut them by FDS. FDS is generic, operating even in the absence of amphipathic helices in the BAR domain, and could in principle apply to any high-friction protein and membrane assembly. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Friction factors and roughness measurements of tubular mineral membranes

    NASA Astrophysics Data System (ADS)

    René, F.; Leuliet, J. C.; Delplace, F.

    1993-08-01

    No direct measurement of the relative roughness is available for mineral porous media because of the low mechanical resistance of such materials. In this study a method for the experimental determination of the internal diameter and the equivalent roughness is proposed for different commercial membranes used in ultrafiltration and microfiltration processes. The use of classical friction factor correlations is also discussed. The main results are the estimation of the hydraulic diameter of tubular membranes and the use of a quadratic form in order to predict friction factors and the equivalent roughness with an accuracy better than 15%.

  20. 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.

  1. Characterizing and simulation the scintillation properties of zinc oxide nanowires in AAO membrane for medical imaging applications

    NASA Astrophysics Data System (ADS)

    Esfandi, F.; Saramad, S.; Rezaei Shahmirzadi, M.

    2017-07-01

    In this work, a new method is proposed for extracting some X-ray detection properties of ZnO nanowires electrodeposited on Anodized Aluminum Oxide (AAO) nanoporous template. The results show that the detection efficiency for 12μm thickness of zinc oxide nano scintillator at an energy of 9.8 keV, near the K-edge of ZnO (9.65 keV), is 24%. The X-rays that interact with AAO can also generate electrons that reach the nano scintillator. The scintillation events of these electrons are seen as a low energy tail in the spectrum. In addition, it is found that all the X-rays that are absorbed in 300 nm thickness of the gold layer on the top of the zinc oxide nanowires can participate in the scintillation process with an efficiency of 6%. Hence, the scintillation detection efficiency of the whole detector for 9.8 keV X-ray energy is 30%. The simulation results from Geant4 and the experimental detected photons per MeV energy deposition are also used to extract the light yield of the zinc oxide nano scintillator. The results show that the light yield of the zinc oxide nanowires deposited by the electrochemical method is approximately the same as for single crystal zinc oxide scintillator (9000). Much better spatial resolution of this nano scintillator in comparison to the bulk ones is an advantage which candidates this nano scintillator for medical imaging applications.

  2. Characterization of anti-tubular basement membrane antibodies in rats.

    PubMed

    Zanetti, M; Wilson, C B

    1983-05-01

    Autoimmune tubulointerstitial nephritis was induced in Brown-Norway (BN) rats by immunization with bovine (Bov) tubular basement membrane (TBM) in complete Freund's adjuvant. Serum antibodies thus produced reacted to a greater extent with Bov than BN TBM antigens by indirect immunofluorescence and by radioimmunoassay with particulate (P) and collagenase-solubilized (CS) TBM. The quantities of antibodies reactive with CS TBM correlated with the intensity of tubulointerstitial pathologic changes. Antibodies eluted from kidneys reactive with BN TBM by indirect immunofluorescence were 508 times more concentrated in the kidney than in the serum, compared with 15 times for Bov TBM-reactive antibodies. The reactivity of eluted antibodies to P BN TBM was inhibited by 70% after absorption with BN CS TBM. A major CS TBM antigen of 42,000 m.w. was identified by polyacrylamide gel electrophoresis. This antigen was present in both Bov and BN TBM, and may be important in triggering autoantibody formation in this model. Lewis rats immunized under the same conditions produced antibodies reactive with BN TBM by immunofluorescence but failed to develop immune deposits in TBM of their own kidneys. Analysis of serum anti-TBM antibodies in Lewis rats revealed a selective lack of reactivity with either homologous or autologous CS TBM. These results suggest that the ability to make an immune response to one or more elements of CS TBM plays a major role in the development of autoimmune tubulointerstitial nephritis in rats.

  3. Extended self-ordering regime in hard anodization and its application to make asymmetric AAO membranes for large pitch-distance nanostructures.

    PubMed

    Kim, Minwoo; Ha, Yoon-Cheol; Nguyen, Truong Nhat; Choi, Hae Young; Kim, Doohun

    2013-12-20

    We report here a fast and reliable hard anodization process to make asymmetric anodic aluminum oxide (AAO) membranes which can serve as a template for large pitch-distance nanostructures. In order to make larger pitch distances possible, the common burning failure associated with the high current density during the conventional constant voltage hard anodization, especially at a voltage higher than a known limit, i.e., 155 V for oxalic acid, was effectively suppressed by using a burning-protective agent. A new self-ordering regime beyond the voltage limit was observed with a different voltage-interpore distance relationship of 2.2 nm V(-1) compared to the reported 2.0 nm V(-1) for hard anodization. Combining a sulfuric acid mild anodization with this new regime of hard anodization, we further demonstrate a scalable process to make an asymmetric membrane with size up to ~47 mm in diameter and ~60 μm in thickness. This free-standing membrane can be used as a template for novel nanopatterned structures such as arrays of quantum dots, nanowires or nanotubes with diameters of a few tens of nanometers and pitch distance of over 400 nm.

  4. Mathematical modeling of methyl ester concentration distribution in a continuous membrane tubular reactor and comparison with conventional tubular reactor

    NASA Astrophysics Data System (ADS)

    Talaghat, M. R.; Jokar, S. M.; Modarres, E.

    2017-10-01

    The reduction of fossil fuel resources and environmental issues made researchers find alternative fuels include biodiesels. One of the most widely used methods for production of biodiesel on a commercial scale is transesterification method. In this work, the biodiesel production by a transesterification method was modeled. Sodium hydroxide was considered as a catalyst to produce biodiesel from canola oil and methanol in a continuous tubular ceramic membranes reactor. As the Biodiesel production reaction from triglycerides is an equilibrium reaction, the reaction rate constants depend on temperature and related linearly to catalyst concentration. By using the mass balance for a membrane tubular reactor and considering the variation of raw materials and products concentration with time, the set of governing equations were solved by numerical methods. The results clearly show the superiority of membrane reactor than conventional tubular reactors. Afterward, the influences of molar ratio of alcohol to oil, weight percentage of the catalyst, and residence time on the performance of biodiesel production reactor were investigated.

  5. Mathematical modeling of methyl ester concentration distribution in a continuous membrane tubular reactor and comparison with conventional tubular reactor

    NASA Astrophysics Data System (ADS)

    Talaghat, M. R.; Jokar, S. M.; Modarres, E.

    2017-04-01

    The reduction of fossil fuel resources and environmental issues made researchers find alternative fuels include biodiesels. One of the most widely used methods for production of biodiesel on a commercial scale is transesterification method. In this work, the biodiesel production by a transesterification method was modeled. Sodium hydroxide was considered as a catalyst to produce biodiesel from canola oil and methanol in a continuous tubular ceramic membranes reactor. As the Biodiesel production reaction from triglycerides is an equilibrium reaction, the reaction rate constants depend on temperature and related linearly to catalyst concentration. By using the mass balance for a membrane tubular reactor and considering the variation of raw materials and products concentration with time, the set of governing equations were solved by numerical methods. The results clearly show the superiority of membrane reactor than conventional tubular reactors. Afterward, the influences of molar ratio of alcohol to oil, weight percentage of the catalyst, and residence time on the performance of biodiesel production reactor were investigated.

  6. 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.

  7. Fabrication of nanopore and nanoparticle arrays with high aspect ratio AAO masks

    NASA Astrophysics Data System (ADS)

    Li, Z. P.; Xu, Z. M.; Qu, X. P.; Wang, S. B.; Peng, J.; Mei, L. H.

    2017-03-01

    How to use high aspect ratio anodic aluminum oxide (AAO) membranes as an etching and evaporation mask is one of the unsolved problems in the application of nanostructured arrays. Here we describe the versatile utilizations of the highly ordered AAO membranes with a high aspect ratio of more than 20 used as universal masks for the formation of various nanostructure arrays on various substrates. The result shows that the fabricated nanopore and nanoparticle arrays of substrates inherit the regularity of the AAO membranes completely. The flat AAO substrates and uneven AAO frontages were attached to the Si substrates respectively as an etching mask, which demonstrates that the two kinds of replication, positive and negative, represent the replication of the mirroring of Si substrates relative to the flat AAO substrates and uneven AAO frontages. Our work is a breakthrough for the broad research field of surface nano-masking.

  8. Fabrication of nanopore and nanoparticle arrays with high aspect ratio AAO masks.

    PubMed

    Li, Z P; Xu, Z M; Qu, X P; Wang, S B; Peng, J; Mei, L H

    2017-03-03

    How to use high aspect ratio anodic aluminum oxide (AAO) membranes as an etching and evaporation mask is one of the unsolved problems in the application of nanostructured arrays. Here we describe the versatile utilizations of the highly ordered AAO membranes with a high aspect ratio of more than 20 used as universal masks for the formation of various nanostructure arrays on various substrates. The result shows that the fabricated nanopore and nanoparticle arrays of substrates inherit the regularity of the AAO membranes completely. The flat AAO substrates and uneven AAO frontages were attached to the Si substrates respectively as an etching mask, which demonstrates that the two kinds of replication, positive and negative, represent the replication of the mirroring of Si substrates relative to the flat AAO substrates and uneven AAO frontages. Our work is a breakthrough for the broad research field of surface nano-masking.

  9. Distribution of IGF receptors in the plasma membrane of proximal tubular cells

    SciTech Connect

    Hammerman, M.R.; Rogers, S. )

    1987-11-01

    To characterize the distribution of receptors for insulin-like growth factors I and II (IGF I and II) in the plasma membrane of the renal proximal tubular cell, the authors measured binding of {sup 125}I-labeled IGF I and {sup 125}I-labeled IGF II to proximal tubular basolateral and brush-border membranes and characterized IGF I-stimulated phosphorylation of detergent-solubilized membranes. {sup 125}I-IGF bound primarily to a 135,000 relative molecular weight (M{sub r}) protein and IGF II to a 260,000 M{sub r} protein in isolated membranes. Binding of {sup 125}I-IGF I was severalfold greater in basolateral than in brush-border membranes. IGF I-stimulated phosphorylation of the 92,000 M{sub r} {beta}-subunit of its receptors could be demonstrated only in basolateral membranes. These findings are consistent with an asymmetrical distribution of receptors for IGF I in the plasma membrane of the renal proximal tubular cell, localization being primary on the basolateral side. In contrast, binding of {sup 125}I-IGF II to isolated basolateral and brush-border membranes was equivalent, suggesting that receptors for this peptide are distributed more symmetrically in the plasma membrane. The findings suggest that the action of IGF I in proximal tubule are mediated via interaction of circulating peptide with specific receptors in the basolateral membrane. However, the findings established the potential for actions of IGF II to be exerted in proximal tubule via interaction with both basolateral and/or brush-border membrane receptors.

  10. Analysis of mass transfer characteristics in a tubular membrane using CFD modeling.

    PubMed

    Yang, Jixiang; Vedantam, Sreepriya; Spanjers, Henri; Nopens, Ingmar; van Lier, Jules B

    2012-10-01

    In contrast to the large amount of research into aerobic membrane bioreactors, little work has been reported on anaerobic membrane bioreactors (AMBRs). As to the application of membrane bioreactors, membrane fouling is a key issue. Membrane fouling generally occurs more seriously in AMBRs than in aerobic membrane bioreactors. However, membrane fouling could be managed through the application of suitable shear stress that can be introduced by the application of a two-phase flow. When the two-phase flow is applied in AMBRs, little is known about the mass transfer characteristics, which is of particular importance, in tubular membranes of AMBRs. In our present work, we have employed fluid dynamic modeling to analyze the mass transfer characteristics in the tubular membrane of a side stream AMBR in which, gas-lift two-phase flow was applied. The modeling indicated that the mass transfer capacity at the membrane surface at the noses of gas bubbles was higher than the mass transfer capacity at the tails of the bubbles, which is in contrast to the results when water instead of sludge is applied. At the given mass transfer rate, the filterability of the sludge was found to have a strong influence on the transmembrane pressure at a steady flux. In addition, the model also showed that the shear stress in the internal space of the tubular membrane was mainly around 20 Pa but could be as high as about 40 Pa due to gas bubble movements. Nonetheless, at these shear stresses a stable particle size distribution was found for sludge particles. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. 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.

  12. Treatment of wastewater containing phenol using a tubular ceramic membrane bioreactor.

    PubMed

    Ersu, C B; Ong, S K

    2008-02-01

    The performance of a membrane bioreactor (MBR) with a tubular ceramic membrane for phenol removal was evaluated under varying hydraulic retention times (HRT) and a fixed sludge residence time (SRT) of 30 days. The tubular ceramic membrane was operated with a mode of 15 minutes of filtration followed by 15 seconds of permeate backwashing at a flux of 250 l m(-2)hr(-1) along with an extended backwashing of 30 seconds every 3 hours of operation, which maintained the transmembrane pressure (TMP) below 100 kPa. Using a simulated municipal wastewater with varying phenol concentrations, the chemical oxygen demand (COD) and phenol removals observed were greater than 88% with excellent suspended solids (SS) removal of 100% at low phenol concentrations (approx. 100 mg l(-1) of phenol). Step increases in phenol concentration showed that inhibition was observed between 600 to 800 mg l(-1) of phenol with decreased sludge production rate, mixed liquor suspended solids (MLSS) concentration, and removal performance. The sludge volume index (SVI) of the biomass increased to about 450 ml g(-1) for a phenol input concentration of 800 mg l(-1). When the phenol concentration was decreased to 100 mg l(-1), the ceramic tubular MBR was found to recover rapidly indicating that the MBR is a robust system retaining most of the biomass. Experimental runs using wastewater containing phenol indicated that the MBR can be operated safely without upsets for concentrations up to 600 mg l(-1) of phenol at 2-4 hours HRT and 30 days SRT.

  13. 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

  14. FBAR Syndapin 1 recognizes and stabilizes highly curved tubular membranes in a concentration dependent manner

    PubMed Central

    Ramesh, Pradeep; Baroji, Younes F.; Reihani, S. Nader S.; Stamou, Dimitrios; Oddershede, Lene B.; Bendix, Poul Martin

    2013-01-01

    Syndapin 1 FBAR, a member of the Bin-amphiphysin-Rvs (BAR) domain protein family, is known to induce membrane curvature and is an essential component in biological processes like endocytosis and formation and growth of neurites. We quantify the curvature sensing of FBAR on reconstituted porcine brain lipid vesicles and show that it senses membrane curvature at low density whereas it induces and reinforces tube stiffness at higher density. FBAR strongly up-concentrates on the high curvature tubes pulled out of Giant Unilamellar lipid Vesicles (GUVs), this sorting behavior is strongly amplified at low protein densities. Interestingly, FBAR from syndapin 1 has a large affinity for tubular membranes with curvatures larger than its own intrinsic concave curvature. Finally, we studied the effect of FBAR on membrane relaxation kinetics with high temporal resolution and found that the protein increases relaxation time of the tube holding force in a density-dependent fashion. PMID:23535634

  15. Growth hormone activates phospholipase C in proximal tubular basolateral membranes from canine kidney

    SciTech Connect

    Rogers, S.A.; Hammerman, M.R. )

    1989-08-01

    To delineate pathways for signal transduction by growth hormone (GH) in proximal tubule, the authors incubated basolateral membranes isolated from canine kidney with human growth hormone (hGH) or human prolactin (hPrl) and measured levels of inositol trisphosphate (InsP{sub 3}) in suspensions and of diacylglycerol extractable from the membranes. Incubation with hGH, but not hPrl, increased levels of InsP{sub 3} and diacylglycerol in a concentration-dependent manner. Half-maximal effects occurred between 0.1 and 1 nM hGH. Increased levels of InsP{sub 3} were measured after as little as 5 sec of incubation with 1 nM hGH, and increase was maximal after 15 sec. Increases were no longer detectable after 60 sec because of dephosphorylation of InsP{sub 3} in membrane suspensions. hGH did not affect rates of dephosphorylation. hGH-stimulated increases in InsP{sub 3} were detectable in membranes suspended in 0, 0.1, and 0.2 {mu}M calcium but not in 0.3 or 1.0 {mu}M calcium. {sup 125}I-labeled hGH-receptor complexes with M{sub r} values of 66,000 and 140,000 were identified in isolated basolateral membranes. The findings establish that GH activates phospholipase C in isolated canine renal proximal tubular basolateral membranes, potentially after binding to a specific receptor. This process could mediate signal transmission by GH across the plasma membrane of the proximal tubular cell and elsewhere.

  16. Shiga toxin induces tubular membrane invaginations for its uptake into cells.

    PubMed

    Römer, Winfried; Berland, Ludwig; Chambon, Valérie; Gaus, Katharina; Windschiegl, Barbara; Tenza, Danièle; Aly, Mohamed R E; Fraisier, Vincent; Florent, Jean-Claude; Perrais, David; Lamaze, Christophe; Raposo, Graça; Steinem, Claudia; Sens, Pierre; Bassereau, Patricia; Johannes, Ludger

    2007-11-29

    Clathrin seems to be dispensable for some endocytic processes and, in several instances, no cytosolic coat protein complexes could be detected at sites of membrane invagination. Hence, new principles must in these cases be invoked to account for the mechanical force driving membrane shape changes. Here we show that the Gb3 (glycolipid)-binding B-subunit of bacterial Shiga toxin induces narrow tubular membrane invaginations in human and mouse cells and model membranes. In cells, tubule occurrence increases on energy depletion and inhibition of dynamin or actin functions. Our data thus demonstrate that active cellular processes are needed for tubule scission rather than tubule formation. We conclude that the B-subunit induces lipid reorganization that favours negative membrane curvature, which drives the formation of inward membrane tubules. Our findings support a model in which the lateral growth of B-subunit-Gb3 microdomains is limited by the invagination process, which itself is regulated by membrane tension. The physical principles underlying this basic cargo-induced membrane uptake may also be relevant to other internalization processes, creating a rationale for conceptualizing the perplexing diversity of endocytic routes.

  17. Basement membrane and apocrine epithelial antigens in differential diagnosis between tubular carcinoma and sclerosing adenosis of the breast.

    PubMed Central

    Ekblom, P; Miettinen, M; Forsman, L; Andersson, L C

    1984-01-01

    The distributions of defined basement membrane proteins in nine pure tubular carcinomas, 10 cases of sclerosing adenosis, and 15 ductal adenocarcinomas were compared. Sections of formalin fixed, paraffin embedded specimens were pretreated with pepsin and then immunostained for laminin, type IV collagen, and basement membrane proteoglycan, components specific for basement membranes. In sclerosing adenosis the tubules were surrounded by a continuous intact basement membrane composed of laminin, type IV collagen, and basement membrane proteoglycan, while the epithelium in the tubular carcinomas was negative for these proteins. The tumours were also analysed for the distribution of the apocrine epithelial antigen (AEA). In contrast to the benign lesions the tubular carcinomas expressed the AEA in a distinct non-polar fashion throughout the cell surface. In normal ducts and in adenosis the AEA was confined exclusively to the luminal surface. These studies suggest that there is a disturbance of cell polarity in tubular carcinomas. It is concluded that a combined analysis of basement membrane proteins and luminal surface antigens is a reliable and convenient way to differentiate between tubular carcinoma and sclerosing adenosis of the breast. Images PMID:6323547

  18. Assessment of a New Silicon Carbide Tubular Honeycomb Membrane for Treatment of Olive Mill Wastewaters.

    PubMed

    Fraga, Maria C; Sanches, Sandra; Crespo, João G; Pereira, Vanessa J

    2017-02-27

    Extremely high removals of total suspended solids and oil and grease were obtained when olive mill wastewaters were filtered using new silicon carbide tubular membranes. These new membranes were used at constant permeate flux to treat real olive mill wastewaters at pilot scale. The filtration conditions were evaluated and optimized in terms of the selection of the permeate flux and flux maintenance strategies employed-backpulsing and backwashing-in order to reduce fouling formation. The results obtained reveal that the combination of backpulses and backwashes helps to maintain the permeate flux, avoids transmembrane pressure increase and decreases the cake resistance. Moreover, membrane cleaning procedures were compared and the main agents responsible for fouling formation identified. Results also show that, under total recirculation, despite an increased concentration of pollutants in the feed stream, the quality of the permeate is maintained. Membrane filtration using silicon carbide membranes is an effective alternative to dissolved air flotation and can be applied efficiently to remove total suspended solids and oil and grease from olive mill wastewaters.

  19. Assessment of a New Silicon Carbide Tubular Honeycomb Membrane for Treatment of Olive Mill Wastewaters

    PubMed Central

    Fraga, Maria C.; Sanches, Sandra; Crespo, João G.; Pereira, Vanessa J.

    2017-01-01

    Extremely high removals of total suspended solids and oil and grease were obtained when olive mill wastewaters were filtered using new silicon carbide tubular membranes. These new membranes were used at constant permeate flux to treat real olive mill wastewaters at pilot scale. The filtration conditions were evaluated and optimized in terms of the selection of the permeate flux and flux maintenance strategies employed—backpulsing and backwashing—in order to reduce fouling formation. The results obtained reveal that the combination of backpulses and backwashes helps to maintain the permeate flux, avoids transmembrane pressure increase and decreases the cake resistance. Moreover, membrane cleaning procedures were compared and the main agents responsible for fouling formation identified. Results also show that, under total recirculation, despite an increased concentration of pollutants in the feed stream, the quality of the permeate is maintained. Membrane filtration using silicon carbide membranes is an effective alternative to dissolved air flotation and can be applied efficiently to remove total suspended solids and oil and grease from olive mill wastewaters. PMID:28264453

  20. 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.

  1. Analysis of diffusion in curved surfaces and its application to tubular membranes.

    PubMed

    Klaus, Colin James Stockdale; Raghunathan, Krishnan; DiBenedetto, Emmanuele; Kenworthy, Anne K

    2016-12-01

    Diffusion of particles in curved surfaces is inherently complex compared with diffusion in a flat membrane, owing to the nonplanarity of the surface. The consequence of such nonplanar geometry on diffusion is poorly understood but is highly relevant in the case of cell membranes, which often adopt complex geometries. To address this question, we developed a new finite element approach to model diffusion on curved membrane surfaces based on solutions to Fick's law of diffusion and used this to study the effects of geometry on the entry of surface-bound particles into tubules by diffusion. We show that variations in tubule radius and length can distinctly alter diffusion gradients in tubules over biologically relevant timescales. In addition, we show that tubular structures tend to retain concentration gradients for a longer time compared with a comparable flat surface. These findings indicate that sorting of particles along the surfaces of tubules can arise simply as a geometric consequence of the curvature without any specific contribution from the membrane environment. Our studies provide a framework for modeling diffusion in curved surfaces and suggest that biological regulation can emerge purely from membrane geometry. © 2016 Klaus, Raghunathan, et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  2. Analysis of diffusion in curved surfaces and its application to tubular membranes

    PubMed Central

    Klaus, Colin James Stockdale; Raghunathan, Krishnan; DiBenedetto, Emmanuele; Kenworthy, Anne K.

    2016-01-01

    Diffusion of particles in curved surfaces is inherently complex compared with diffusion in a flat membrane, owing to the nonplanarity of the surface. The consequence of such nonplanar geometry on diffusion is poorly understood but is highly relevant in the case of cell membranes, which often adopt complex geometries. To address this question, we developed a new finite element approach to model diffusion on curved membrane surfaces based on solutions to Fick’s law of diffusion and used this to study the effects of geometry on the entry of surface-bound particles into tubules by diffusion. We show that variations in tubule radius and length can distinctly alter diffusion gradients in tubules over biologically relevant timescales. In addition, we show that tubular structures tend to retain concentration gradients for a longer time compared with a comparable flat surface. These findings indicate that sorting of particles along the surfaces of tubules can arise simply as a geometric consequence of the curvature without any specific contribution from the membrane environment. Our studies provide a framework for modeling diffusion in curved surfaces and suggest that biological regulation can emerge purely from membrane geometry. PMID:27733625

  3. Bioengineering of living renal membranes consisting of hierarchical, bioactive supramolecular meshes and human tubular cells.

    PubMed

    Dankers, Patricia Y W; Boomker, Jasper M; Huizinga-van der Vlag, Ali; Wisse, Eva; Appel, Wilco P J; Smedts, Frank M M; Harmsen, Martin C; Bosman, Anton W; Meijer, W; van Luyn, Marja J A

    2011-01-01

    Maintenance of polarisation of epithelial cells and preservation of their specialized phenotype are great challenges for bioengineering of epithelial tissues. Mimicking the basement membrane and underlying extracellular matrix (ECM) with respect to its hierarchical fiber-like morphology and display of bioactive signals is prerequisite for optimal epithelial cell function in vitro. We report here on a bottom-up approach based on hydrogen-bonded supramolecular polymers and ECM-peptides to make an electro-spun, bioactive supramolecular mesh which can be applied as synthetic basement membrane. The supramolecular polymers used, self-assembled into nano-meter scale fibers, while at micro-meter scale fibers were formed by electro-spinning. We introduced bioactivity into these nano-fibers by intercalation of different ECM-peptides designed for stable binding. Living kidney membranes were shown to be bioengineered through culture of primary human renal tubular epithelial cells on these bioactive meshes. Even after a long-term culturing period of 19 days, we found that the cells on bioactive membranes formed tight monolayers, while cells on non-active membranes lost their monolayer integrity. Furthermore, the bioactive membranes helped to support and maintain renal epithelial phenotype and function. Thus, incorporation of ECM-peptides into electro-spun meshes via a hierarchical, supramolecular method is a promising approach to engineer bioactive synthetic membranes with an unprecedented structure. This approach may in future be applied to produce living bioactive membranes for a bio-artificial kidney. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Energy transfer dynamics in an RC-LH1-PufX tubular photosynthetic membrane

    NASA Astrophysics Data System (ADS)

    Hsin, J.; Strümpfer, J.; Şener, M.; Qian, P.; Hunter, C. N.; Schulten, K.

    2010-08-01

    Light absorption and the subsequent transfer of excitation energy are the first two steps in the photosynthetic process, carried out by protein-bound pigments, mainly bacteriochlorophylls (BChls), in photosynthetic bacteria. BChls are anchored in light-harvesting (LH) complexes, such as light-harvesting complex I (LH1), which directly associates with the reaction center (RC), forming the RC-LH1 core complex. In Rhodobacter sphaeroides, RC-LH1 core complexes contain an additional protein, PufX, and assemble into dimeric RC-LH1-PufX core complexes. In the absence of LH complex II (LH2), the former complexes can aggregate into a helically ordered tubular photosynthetic membrane. We have examined the excitation transfer dynamics in a single RC-LH1-PufX core complex dimer using the hierarchical equations of motion for dissipative quantum dynamics that accurately, yet in a computationally costly manner, treat the coupling between BChls and their protein environment. A widely employed description, the generalized Förster (GF) theory, was also used to calculate the transfer rates of the same excitonic system in order to verify the accuracy of this computationally cheap method. Additionally, in light of the structural uncertainties in the Rba. sphaeroides RC-LH1-PufX core complex, geometrical alterations were introduced into the BChl organization. It is shown that the energy transfer dynamics are not affected by the considered changes in the BChl organization and that the GF theory provides accurate transfer rates. An all-atom model for a tubular photosynthetic membrane is then constructed on the basis of electron microscopy data, and the overall energy transfer properties of this membrane are computed.

  5. Fracture modes in tubular LSFCO ceramic membranes under graded reducing conditions

    SciTech Connect

    Nagendra, N.; Biswas, S.; Nithyanantham, T.; Bandopadhyay, S.

    2013-06-01

    Highlights: ► Microstructural evolution in LSFCO membranes under graded environment is reported. ► The role of chemically induced stresses and oxygen deficiency is evaluated. ► The stress distribution is modeled by a point defect model. - Abstract: Chromium (III) oxide (Cr{sub 2}O{sub 3})-doped LaSrFeO{sub 3} perovskite, La{sub 0.2}Sr{sub 0.8}Fe{sub 0.8}Cr{sub 0.2}O{sub 3−δ} (LSFCO), is being considered as a potential material for applications in solid oxide fuel cells, gas separation membranes, and electrochemical reactors because of its high electro-catalytic activity. Similar to other perovskites, the performance and mechanical strength of LSFCO materials are significantly affected by environment and temperature. Here, we report a fracture gradient phenomenon in tubular C-ring-shaped LSFCO ceramic membranes under graded reducing conditions. The graded reducing condition was produced by flushing N{sub 2} on the outer side of the C-ring membranes at 1000 °C while keeping the inner side untreated. The rings were then diametrically compressed to fracture, and the resultant fracture morphology was analyzed with a scanning electron microscope (SEM). A fracture gradient with three distinct regions across the thickness of the membranes was identified on the split surfaces. In the outer region of the C-ring specimen exposed to N{sub 2}, a mixed inter/transgranular fracture with a predominant intergranular pattern was observed. In the middle section of the fracture surface, a characteristic transgranular fracture of the perovskite grains was found. At the inner region of the ring, a mixed inter/transgranular fracture with a predominant transgranular pattern occurred. The mechanism of gradient fractures was attributed both to chemically induced stresses caused by oxygen diffusion and to the formation of a separate phase of oxygen-deficient perovskite in the parent perovskite. The stresses generated were modeled by a point defect model. This work provides

  6. Differentiation of pancreatic acinar carcinoma cells cultured on rat testicular seminiferous tubular basement membranes

    SciTech Connect

    Watanabe, T.K.; Hansen, L.J.; Reddy, N.K.; Kanwar, Y.S.; Reddy, J.K.

    1984-11-01

    The use of rat testicular seminiferous tubular basement membrane (STBM) segments as a model substratum for the in vitro maintenance of tumor cells dissociated from a transplantable pancreatic acinar rat carcinoma is described. Ultrastructurally pure, hollow tubular segments of STBM were prepared by mechanical disaggregation, DNase digestion, and deoxycholate treatment. Dissociated pancreatic acinar carcinoma cells adhered readily to STBM segments within 1 to 6 hr, and these STBM-tumor cell aggregates were maintained for up to 7 days in serum-free chemically defined medium supplemented with hydrocortisone, insulin, vitamin C, and soybean trypsin inhibitor. The tumor cells formed acinar-like clusters and displayed intercellular junctions and polarization of secretory granules toward the center of these clusters. By 4 days, virtually all cells of this acinar carcinoma maintained on STBM in supplemented chemically defined medium contained numerous secretory granules. Cell replication, as determined by (/sup 3/H)thymidine autoradiography, ceased within 18 hr of attachment of neoplastic cells to STBM; however, all cells incorporated (/sup 3/H)leucine as evidenced by light and electron microscopic autoradiography. In addition, two-dimensional analysis and fluorography of newly synthesized secretory proteins discharged by these cells in response to carbamylcholine revealed the presence of Mr 24,000 protein and 19 other secretory proteins characteristic of this tumor. The culture system utilizing STBM and supplemented chemically defined medium should allow investigation of the effects of a variety of factors on morphogenesis, cytodifferentiation, and gene expression in pancreatic acinar tumors.

  7. 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.

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

    SciTech Connect

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

    2016-01-15

    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.

  9. Membrane process treatment for greywater recycling: investigations on direct tubular nanofiltration.

    PubMed

    Hourlier, F; Massé, A; Jaouen, P; Lakel, A; Gérente, C; Faur, C; Cloirec, P Le

    2010-01-01

    On-site greywater recycling and reuse is one of the main ways to reduce potable water requirement in urban areas. Direct membrane filtration is a promising technology to recycle greywater on-site. This study aimed at selecting a tubular nanofiltration (NF) membrane and its operating conditions in order to treat and reuse greywater in buildings. To do so, a synthetic greywater (SGW) was reconstituted in order to conduct experiments on a reproducible effluent. Then, three PCI NF membranes (AFC30, AFC40 and AFC80) having distinct molecular weight cut-offs were tested to recycle this SGW with a constant concentration at 25°C at two different transmembrane pressures (20 and 35 bar). The best results were obtained with AFC80 at 35 bar: the flux was close to 50 L m⁻²  h⁻¹, retentions of 95% for chemical oxygen demand and anionic surfactants were observed, and no Enterococcus were detected in the permeate. The performances of AFC80 were also evaluated on a real greywater: fluxes and retentions were similar to those observed on SGW. These results demonstrate the effectiveness of direct nanofiltration to recycle and reuse greywater.

  10. Interference color of anodized aluminum oxide (AAO) films for sensor application

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Wang, Ming L.; Indacochea, J. Ernesto; Wang, H. Hau

    2009-03-01

    Anodized aluminum oxide (AAO) membranes are fabricated under different anodization potentials in dilute sulfuric acid. Here we report the growth of AAO under 10, 15, 20, and 25V. These AAO membranes consist of nanopores with pore-to-pore distance from 35 to 69 nm. When AAO membranes are kept thin (less than ~500 nm), together with the unreacted aluminum substrate, interference colors are observed. The inference color of the membrane is changed by its thickness and the pore-to-pore distance, which is controlled by the anodization time and voltage, respectively. By using thin film interference model to analyze the UV-Vis reflectance spectra, we can extract the thickness of the membrane. Thus the linear growth of AAO membrane in sulfuric acid with time during the first 15 minutes is validated. Coating poly (styrene sulfonate) (PSS) sodium salt and poly (allylamine hydrochloride) (PAH) layer by layer over the surface of AAO membrane consistently shifts the interference colors. The red shift of the UV-Vis reflectance spectrum is correlated to the number of layers. This color change due to molecular attachment and increasing thickness is a promising method for chemical sensing.

  11. Luminescence parameters of InP/ZnS@AAO nanostructures

    SciTech Connect

    Savchenko, S. S.; Vokhmintsev, A. S.; Weinstein, I. A.

    2016-03-29

    Nanostructured membranes of anodic aluminum oxide (AAO) with InP/ZnS semiconductor nanocrystals deposited in pores were synthesized by electrochemical technique, physical deposition and post processing in an ultrasonic bath. Photoluminescence spectra of the samples were studied. Fluorescent properties of the quantum dots are found to be retained after the deposition. The color range is illustrated that can be covered using membranes annealed at temperatures < 900°C and by varying the concentration of the deposited InP/ZnS nanocrystals. Chromaticity coordinates and correlated color temperature for the fabricated white InP/ZnS@AAO phosphor are (0.21, 0.26) and 4115 K, respectively.

  12. 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.

  13. Low micromolar concentrations of cadmium and mercury ions activate peritubular membrane K+ conductance in proximal tubular cells of frog kidney.

    PubMed

    Nesovic-Ostojic, Jelena; Cemerikic, Dusan; Dragovic, Simon; Milovanovic, Aleksandar; Milovanovic, Jovica

    2008-03-01

    The present study was designed to investigate the acute effects of extracellular low micromolar concentrations of cadmium and mercury ions on the peritubular cell membrane potential and its potassium selectivity in proximal tubular cells of the frog kidney. Peritubular exposure to 3 micromol/L Cd(2+) or 1 micromol/L Hg(2+) led to a rapid, sustained and reversible hyperpolarization of the peritubular cell membrane, paralleled by an increase in fractional K(+) conductance. Peritubular barium abolished hyperpolarization of the peritubular cell membrane to peritubular 3 micromol/L Cd(2+) or 1 micromol/L Hg(2+). Perfusing the lumen with 10 mmol/L l-alanine plus/minus 3 micromol/L Cd(2+) or Hg(2+) did not modify rapid depolarization and rate of slow repolarization of the peritubular cell membrane potential. In conclusion, low micromolar concentrations of Cd(2+) and Hg(2+) increase K(+) conductive pathway in the peritubular cell membrane and in this way can enhance ability of proximal renal tubular cells to maintain the driving force for electrogenic Na(+) and substrate reabsorption.

  14. Manufacture and optimization of low-cost tubular ceramic supports for membrane filtration: application to algal solution concentration.

    PubMed

    Issaoui, Mansour; Limousy, Lionel; Lebeau, Bénédicte; Bouaziz, Jamel; Fourati, Mohieddine

    2017-01-05

    Low-cost tubular macroporous supports for ceramic membranes were elaborated using the extrusion method, followed by curing, debinding, and sintering processes, from a powder mixture containing kaolin, starch, and sand. The obtained substrates were characterized using mercury intrusion porosimetry, water absorption test, water permeability, scanning electron microscopy, and three-point bending test to evaluate the effects of the additives on the relevant characteristics. According to experimental results, adding the starch ratio to the kaolin powder shows a notable impact on the membrane porosity and consequently on the water permeability of the tubular supports, whereas their mechanical strength decreased compared to those prepared from kaolin alone. It has been shown that the addition of an appropriate amount of starch to the ceramic paste leads to obtaining membrane supports with the desired porosity. Indeed, the water permeability increased significantly from 20 to 612 L h(-1) m(-2) bar(-1) for samples without and with 20 wt% of starch, respectively, as well as the open porosity, the apparent porosity, and the pore size distribution. The bending strength decreased slightly and reached about 4 MPa for samples with the highest starch amounts. On the other hand, the incorporation of sand in a mixture of kaolin + 10 wt% starch increased the mechanical strength and the water permeability. The samples containing 3 wt% of sand exhibited a bending strength four times higher than the supports without sand; the water permeability measured was about 221 L h(-1) m(-2) bar(-1). These elaborated tubular supports for membrane are found to be suitable for solution concentration; they were applied for algal solution and are also easily cleaned by water.

  15. The use of fibrous, supramolecular membranes and human tubular cells for renal epithelial tissue engineering: towards a suitable membrane for a bioartificial kidney.

    PubMed

    Dankers, Patricia Y W; Boomker, Jasper M; Huizinga-van der Vlag, Ali; Smedts, Frank M M; Harmsen, Martin C; van Luyn, Marja J A

    2010-11-10

    A bioartificial kidney, which is composed of a membrane cartridge with renal epithelial cells, can substitute important kidney functions in patients with renal failure. A particular challenge is the maintenance of monolayer integrity and specialized renal epithelial cell functions ex vivo. We hypothesized that this can be improved by electro-spun, supramolecular polymer membranes which show clear benefits in ease of processability. We found that after 7 d, in comparison to conventional microporous membranes, renal tubular cells cultured on top of our fibrous supramolecular membranes formed polarized monolayers, which is prerequisite for a well-functioning bioartificial kidney. In future, these supramolecular membranes allow for incorporation of peptides that may increase cell function even further.

  16. [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.

  17. Using an improved 1D boundary layer model with CFD for flux prediction in gas-sparged tubular membrane ultrafiltration.

    PubMed

    Smith, R; Taha, T; Cui, Z F

    2005-01-01

    Tubular membrane ultrafiltration and microfiltration are important industrial separation and concentration processes. Process optimisation requires reduction of membrane build-up. Gas slug introduction has been shown to be a useful approach for flux enhancement. However, process quantification is required for design and optimisation. In this work we employ a non-porous wall CFD model to quantify hydrodynamics in the two-phase slug flow process. Mass transfer is subsequently quantified from wall shear stress, which was determined from the CFD. The mass transfer model is an improved one-dimensional boundary layer model, which empirically incorporates effects of wall suction and analytically includes edge effects for circular conduits. Predicted shear stress profiles are in agreement with experimental results and flux estimates prove more reliable than that from previous models. Previous models ignored suction effects and employed less rigorous fluid property inclusion, which ultimately led to under-predictive flux estimates. The presented model offers reliable process design and optimisation criteria for gas-sparged tubular membrane ultrafiltration.

  18. Bioelectricity generation in an integrated system combining microbial fuel cell and tubular membrane reactor: effects of operation parameters performing a microbial fuel cell-based biosensor for tubular membrane bioreactor.

    PubMed

    Wang, Jie; Zheng, Yawen; Jia, Hui; Zhang, Hongwei

    2014-10-01

    A bio-cathode microbial fuel cell (MFC) with tubular membrane was integrated to construct a microbial fuel cell-tubular membrane bioreactor (MFC-TMBR) system, in which the bio-cathode MFC was developed as a biosensor for COD real-time monitoring in TMBR and the performance was analyzed in terms of its current variation caused by operation parameters. With a constant anode potential, the effect of HRT demonstrated that higher rate of mass transport increased the response of the system. The system was further explored an inverse relationship between TMP and current peak by using EPS concentration under the different MLSS concentration. The sensor output had a linear relationship with COD up to 1000mg/L (regression coefficient, R(2)=0.97) and MLSS (regression coefficient, R(2)=0.94). The simple and compact bio-cathode MFC biosensor for TMBR using MFC-TMBR integrated system showed promising potential for direct and economical COD online monitoring, and provided an opportunity to widen the application of MFC-based biosensor.

  19. Increased curvature of hollow fiber membranes could up-regulate differential functions of renal tubular cell layers.

    PubMed

    Shen, Chong; Meng, Qin; Zhang, Guoliang

    2013-08-01

    Tissue engineering devices as in vitro cell culture systems in scaffolds has encountered the bottleneck due to their much lower cell functions than real tissues/organs in vivo. Such situation has been improved in some extent by mimicking the cell microenvironments in vivo from either chemical or physical ways. However, microenvironmental curvature, commonly seen in real tissues/organs, has never been manipulated to regulate the cell performance in vitro. In this regard, this paper fabricated polysulfone membranes with or without polyethylene glycol modification to investigate the impact of curvature on two renal tubular cells. Regardless the varying membrane curvatures among hollow fiber membranes of different diameters and flat membrane of zero curvature, both renal cells could well attach at 4 h of seeding and form similar confluent layers at 6 days on each membrane. Nevertheless, the renal cells on hollow fibers, though showing confluent morphology as those on flat membranes, expressed higher renal functions and, moreover, the renal functions significantly increased with the membrane curvature among hollow fibers. Such upregulation on functions was unassociated with mass transport barrier of hollow fibers, because the cultures on lengthwise cut hollow fibers without mass transfer barrier showed same curvature effect on renal functions as whole hollow fibers. It could be proposed that the curvature of hollow fiber membrane approaching to the large curvature in kidney tubules increased the mechanical stress in the renal cells and thus might up-regulate the renal cell functions. In conclusion, the increase of substrate curvature could up-regulate the cell functions without altering the confluent cell morphology and this finding will facilitate the design of functional tissue engineering devices.

  20. Different Densities of Na-Ca Exchange Current in T-Tubular and Surface Membranes and Their Impact on Cellular Activity in a Model of Rat Ventricular Cardiomyocyte

    PubMed Central

    2017-01-01

    The ratio of densities of Na-Ca exchanger current (INaCa) in the t-tubular and surface membranes (INaCa-ratio) computed from the values of INaCa and membrane capacitances (Cm) measured in adult rat ventricular cardiomyocytes before and after detubulation ranges between 1.7 and 25 (potentially even 40). Variations of action potential waveform and of calcium turnover within this span of the INaCa-ratio were simulated employing previously developed model of rat ventricular cell incorporating separate description of ion transport systems in the t-tubular and surface membranes. The increase of INaCa-ratio from 1.7 to 25 caused a prolongation of APD (duration of action potential at 90% repolarisation) by 12, 9, and 6% and an increase of peak intracellular Ca2+ transient by 45, 19, and 6% at 0.1, 1, and 5 Hz, respectively. The prolonged APD resulted from the increase of INaCa due to the exposure of a larger fraction of Na-Ca exchangers to higher Ca2+ transients under the t-tubular membrane. The accompanying rise of Ca2+ transient was a consequence of a higher Ca2+ load in sarcoplasmic reticulum induced by the increased Ca2+ cycling between the surface and t-tubular membranes. However, the reason for large differences in the INaCa-ratio assessed from measurements in adult rat cardiomyocytes remains to be explained. PMID:28321411

  1. 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

  2. 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 ...

  3. 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 ...

  4. 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

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

    PubMed Central

    Suski, Szymon

    2016-01-01

    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

  6. 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

  7. Bending stiffness depends on curvature of ternary lipid mixture tubular membranes.

    PubMed

    Tian, Aiwei; Capraro, Benjamin R; Esposito, Cinzia; Baumgart, Tobias

    2009-09-16

    Lipid and protein sorting and trafficking in intracellular pathways maintain cellular function and contribute to organelle homeostasis. Biophysical aspects of membrane shape coupled to sorting have recently received increasing attention. Here we determine membrane tube bending stiffness through measurements of tube radii, and demonstrate that the stiffness of ternary lipid mixtures depends on membrane curvature for a large range of lipid compositions. This observation indicates amplification by curvature of cooperative lipid demixing. We show that curvature-induced demixing increases upon approaching the critical region of a ternary lipid mixture, with qualitative differences along two roughly orthogonal compositional trajectories. Adapting a thermodynamic theory earlier developed by M. Kozlov, we derive an expression that shows the renormalized bending stiffness of an amphiphile mixture membrane tube in contact with a flat reservoir to be a quadratic function of curvature. In this analytical model, the degree of sorting is determined by the ratio of two thermodynamic derivatives. These derivatives are individually interpreted as a driving force and a resistance to curvature sorting. We experimentally show this ratio to vary with composition, and compare the model to sorting by spontaneous curvature. Our results are likely to be relevant to the molecular sorting of membrane components in vivo.

  8. 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

  9. Analysis of shear stress and energy consumption in a tubular airlift membrane system.

    PubMed

    Ratkovich, N; Chan, C C V; Berube, P R; Nopens, I

    2011-01-01

    Application of a two-phase slug flow in side-stream membrane bioreactors (MBRs) has proven to increase the permeate flux and decrease fouling through a better control of the cake layer. Past literature has shown that the hydrodynamics near the membrane surface have an impact on the degree of fouling by imposing high shear stress near the surface of the membrane. Previously, shear stress histograms (SSH) have been introduced to summarize results from an experimental setup developed to investigate the shear stress imposed on the surface of a membrane under different two-phase flow conditions (gas and liquid) by varying the flow of each phase. Bimodal SSHs were observed, with peaks corresponding to the shear induced by the liquid and gas flow respectively. In this contribution, SSHs are modelled using simple empirical relationships. These are used to identify the two-phase flow conditions that optimize fouling control. Furthermore, the total energy consumption of the system was estimated based on the two-phase pressure drop. It was found that low liquid and high gas flow rates (ratio of approx. 4) balanced the peaks and minimized the energy consumption.

  10. The Matrix protein M1 from influenza C virus induces tubular membrane invaginations in an in vitro cell membrane model

    PubMed Central

    Saletti, David; Radzimanowski, Jens; Effantin, Gregory; Midtvedt, Daniel; Mangenot, Stéphanie; Weissenhorn, Winfried; Bassereau, Patricia; Bally, Marta

    2017-01-01

    Matrix proteins from enveloped viruses play an important role in budding and stabilizing virus particles. In order to assess the role of the matrix protein M1 from influenza C virus (M1-C) in plasma membrane deformation, we have combined structural and in vitro reconstitution experiments with model membranes. We present the crystal structure of the N-terminal domain of M1-C and show by Small Angle X-Ray Scattering analysis that full-length M1-C folds into an elongated structure that associates laterally into ring-like or filamentous polymers. Using negatively charged giant unilamellar vesicles (GUVs), we demonstrate that M1-C full-length binds to and induces inward budding of membrane tubules with diameters that resemble the diameter of viruses. Membrane tubule formation requires the C-terminal domain of M1-C, corroborating its essential role for M1-C polymerization. Our results indicate that M1-C assembly on membranes constitutes the driving force for budding and suggest that M1-C plays a key role in facilitating viral egress. PMID:28120862

  11. 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

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

    SciTech Connect

    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 separation 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.

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

    DOE PAGES

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

    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

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

    PubMed Central

    DiFranco, Marino

    2011-01-01

    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 (INa, ILi; 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 ILi was ∼30% smaller than for INa, suggesting a Li-blocking effect. ILi 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 ILi. Simultaneously measured maximal overshoot and peak ILi were 54 ± 5% and 773 ± 53 µA/cm2, respectively. Radial cable model simulations predicted the properties of ILi and di-8-ANEPPS transients when TTS access resistances of 10–20 Ωcm2, 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 ILi, 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 understanding of the radial and

  15. The breakage of nanopore in AAO template

    NASA Astrophysics Data System (ADS)

    Jia, X. R.; Wang, H.; Zhen, Y.

    2016-07-01

    In the present work, AAO template is fabricated in oxalic acid solution under a constant voltage by several steps. By the Bernoulli principle, the pressure on the wall of hole increases which lead to the breakage of nanopore as a result of the reducing effective migration rate of Al3+. The quantity of the breakage of nanopore rises with the increase of the concentration of Al3+. Further, nanopore is closed by oxide due to the decrease of effective migration rate of Al3+. Finally, a “nanoflower-like” shape can be observed in experiments.

  16. 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

  17. The AAO fiber instrument data simulator

    NASA Astrophysics Data System (ADS)

    Goodwin, Michael; Farrell, Tony; Smedley, Scott; Heald, Ron; Heijmans, Jeroen; De Silva, Gayandhi; Carollo, Daniela

    2012-09-01

    The fiber instrument data simulator is an in-house software tool that simulates detector images of fiber-fed spectrographs developed by the Australian Astronomical Observatory (AAO). In addition to helping validate the instrument designs, the resulting simulated images are used to develop the required data reduction software. Example applications that have benefited from the tool usage are the HERMES and SAMI instrumental projects for the Anglo-Australian Telescope (AAT). Given the sophistication of these projects an end-to-end data simulator that accurately models the predicted detector images is required. The data simulator encompasses all aspects of the transmission and optical aberrations of the light path: from the science object, through the atmosphere, telescope, fibers, spectrograph and finally the camera detectors. The simulator runs under a Linux environment that uses pre-calculated information derived from ZEMAX models and processed data from MATLAB. In this paper, we discuss the aspects of the model, software, example simulations and verification.

  18. 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.

  19. Hydrogen-Permeable Tubular Membrane Reactor: Promoting Conversion and Product Selectivity for Non-Oxidative Activation of Methane over an Fe©SiO2 Catalyst.

    PubMed

    Sakbodin, Mann; Wu, Yiqing; Oh, Su Cheun; Wachsman, Eric D; Liu, Dongxia

    2016-12-23

    Non-oxidative methane conversion over Fe©SiO2 catalyst was studied for the first time in a hydrogen (H2 ) permeable tubular membrane reactor. The membrane reactor is composed of a mixed ionic-electronic SrCe0.7 Zr0.2 Eu0.1 O3-δ thin film (≈20 μm) supported on the outer surface of a one-end capped porous SrCe0.8 Zr0.2 O3-δ tube. Significant improvement in CH4 conversion was achieved upon H2 removal from the membrane reactor compared to that in a fixed-bed reactor. The Fe©SiO2 catalyst in the H2 permeable membrane reactor demonstrated a stable ≈30 % C2+ single-pass yield, with up to 30 % CH4 conversion and 99 % selectivity to C2 (ethylene and acetylene) and aromatic (benzene and naphthalene) products, at the tested conditions. The selectivity towards C2 or aromatics was manipulated purposely by adding H2 into or removing H2 from the membrane reactor feed and permeate gas streams. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Free Fatty Acid Effects on the Atrial Myocardium: Membrane Ionic Currents Are Remodeled by the Disruption of T-Tubular Architecture

    PubMed Central

    O’Connell, Ryan P.; Musa, Hassan; Gomez, Mario San Martin; Avula, Uma Mahesh; Herron, Todd J.; Kalifa, Jerome; Anumonwo, Justus M. B.

    2015-01-01

    Background Epicardial adiposity and plasma levels of free fatty acids (FFAs) are elevated in atrial fibrillation, heart failure and obesity, with potentially detrimental effects on myocardial function. As major components of epicardial fat, FFAs may be abnormally regulated, with a potential to detrimentally modulate electro-mechanical function. The cellular mechanisms underlying such effects of FFAs are unknown. Objective To determine the mechanisms underlying electrophysiological effects of palmitic (PA), stearic (SA) and oleic (OA) FFAs on sheep atrial myocytes. Methods We used electrophysiological techniques, numerical simulations, biochemistry and optical imaging to examine the effects of acutely (≤ 15 min), short-term (4–6 hour) or 24-hour application of individual FFAs (10 μM) on isolated ovine left atrial myocytes (LAMs). Results Acute and short-term incubation in FFAs resulted in no differences in passive or active properties of isolated left atrial myocytes (LAMs). 24-hour application had differential effects depending on the FFA. PA did not affect cellular passive properties but shortened (p<0.05) action potential duration at 30% repolarization (APD30). APD50 and APD80 were unchanged. SA had no effect on resting membrane potential but reduced membrane capacitance by 15% (p<0.05), and abbreviated APD at all values measured (p≤0.001). OA did not significantly affect passive or active properties of LAMs. Measurement of the major voltage-gated ion channels in SA treated LAMs showed a ~60% reduction (p<0.01) of the L-type calcium current (ICa-L) and ~30% reduction (p<0.05) in the transient outward potassium current (ITO). A human atrial cell model recapitulated SA effects on APD. Optical imaging showed that SA incubated for 24 hours altered t-tubular structure in isolated cells (p<0.0001). Conclusions SA disrupts t-tubular architecture and remodels properties of membrane ionic currents in sheep atrial myocytes, with potential implications in

  1. Effect of betamethasone on Na-K-ATPase activity and basal and lateral cell membranes in proximal tubular cells during early development.

    PubMed

    Igarashi, Y; Aperia, A; Larsson, L; Zetterström, R

    1983-08-01

    The mechanism by which betamethasone induces Na-K-ATPase activity in developing tissue was studied in homogenates of proximal tubular cells from 10-day-old rats. A significant increase in Na-K-ATPase activity occurred after 5 micrograms . 100 g-1 . 12 h-1 X 2 beta-methasone and a maximal increase after 15-60 micrograms . 100 g-1 . 12 h-1 X 2. Following a single dose of 60 micrograms . 100 g-1 betamethasone Na-K-ATPase activity increased significantly after 16 h and maximally after 24-30 h. The 16-h time lag suggests that betamethasone does not act only directly on Na-K-ATPase synthesis. Betamethasone 60 micrograms . 100 g-1 increases Na-K-ATPase activity significantly in kidneys in which glomerular filtration rate is reduced by ureteral ligation, but the increase is significantly less pronounced than in kidneys with intact ureters, suggesting that the induction is not mediated only by alterations in sodium supply. Twenty-four hours after 10-60 micrograms . 100 g-1 betamethasone there was no significant increase in glucose-6-phosphatase and Mg-ATPase activity in 10-day-old rats or in Na-K-ATPase activity in 40-day-old rats. The basal and lateral cell membranes of the proximal tubular cells were not significantly increased 24 h after 60 micrograms . 100 g-1 betamethasone. Accordingly, structural development is not a prerequisite for enzymatic differentiation.

  2. 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.

  3. Preparative fractionation of protein, RNA, and plasmid DNA using centrifugal precipitation chromatography with tubular dialysis membrane inside a convoluted tubing as separation channel.

    PubMed

    Tomanee, Panarat; Hsu, James T; Ito, Yoichiro

    2006-01-01

    Fractionation of clarified E. coli lysate components in bench-scale and preparative-scale centrifugal precipitation chromatography (CPC), using a solution of cationic surfactant cetyltrimethylammonium bromide (CTAB) containing 0.5 M NaCl as precipitant, are compared here. Step gradient of CTAB from 0.50% to 0.16% (w/v) gave a successful fractionation in bench-scale CPC; however, a linear gradient of lower CTAB concentration, 0.20-0% (w/v), was used in the preparative scale and resulted in similar fractionation. The preparative-scale CPC has a superior sample loading capacity by the use of tubular dialysis membrane inside convoluted tubing as the separation channel. In this study, the quantity of the sample loaded into the preparative CPC was about 15 times more than that in the bench scale, and in a single run the preparative CPC could prepare approximately 3 mg of plasmid DNA with about 96% of RNA removed. The higher surface area per length of the separation channel in the preparative CPC was believed to benefit mass transfer of CTAB across the membrane, leading to less CTAB being required in the process.

  4. Quality, Safety, and Value: The Current AAOS Initiatives.

    PubMed

    Sanders, James O

    2015-01-01

    The AAOS is committed to helping orthopaedists provide safe, effective, and high-quality care for their patients. There are a number of very active initiatives focused on patient safety, team performance, and evidence-based quality and value including clinical practice guidelines and appropriate use criteria. This article describes those initiatives.

  5. Adherence to the AAOS upper-extremity clinical practice guidelines.

    PubMed

    Matzon, Jonas L; Lutsky, Kevin F; Maloney, Michael; Beredjiklian, Pedro K

    2013-11-01

    The American Academy of Orthopaedic Surgeons (AAOS) recently developed several clinical practice guidelines (CPGs) involving upper-extremity conditions. The purpose of this study was to evaluate the adherence to these CPGs by members of the American Society for Surgery of the Hand (ASSH). An e-mail containing a brief study description and access to the survey was sent to ASSH current and candidate members. The survey contained questions involving the existing upper-extremity AAOS CPGs: diagnosis and treatment of carpal tunnel syndrome, treatment of distal radius fractures, and treatment of glenohumeral arthritis. Overall, 469 responses were obtained, for a response rate of 32%. Descriptive statistics were used to evaluate the responses. Members of ASSH do not universally adhere to the AAOS CPGs. For patients with carpal tunnel syndrome, 53% of respondents wait the recommended time to change nonoperative treatment after failure of a given modality, and 32% of respondents always order electrodiagnostic testing when considering surgery. Furthermore, 30% of respondents immobilize the wrist postoperatively. In regard to distal radius fractures, 11% of respondents always prescribe vitamin C after treatment, and 49% respondents never do so. However, ASSH members follow some of the recommendations. These include nighttime splinting (98%) and corticosteroid injections (85%) in the nonoperative treatment of carpal tunnel syndrome. For distal radius fractures, almost 85% of respondents consider the suggested postreduction criteria when determining operative versus cast treatment. Further study is warranted to understand the reasons for and possible solutions to the inconsistent adherence to the AAOS CPGs.

  6. Enhanced ionic conductivity of AgI nanowires/AAO composites fabricated by a simple approach

    NASA Astrophysics Data System (ADS)

    Liu, Li-Feng; Lee, Seung-Woo; Li, Jing-Bo; Alexe, Marin; Rao, Guang-Hui; Zhou, Wei-Ya; Lee, Jae-Jong; Lee, Woo; Gösele, Ulrich

    2008-12-01

    AgI nanowires/anodic aluminum oxide (AgI NWs/AAO) composites have been fabricated by a simple approach, which involves the thermal melting of AgI powders on the surface of the AAO membrane, followed by the infiltration of the molten AgI inside the nanochannels. As-prepared AgI nanowires have corrugated outer surfaces and are polycrystalline according to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. X-ray diffraction (XRD) shows that a considerable amount of 7H polytype AgI exists in the composites, which is supposed to arise from the interfacial interactions between the embedded AgI and the alumina. AC conductivity measurements for the AgI nanowires/AAO composites exhibit a notable conductivity enhancement by three orders of magnitude at room temperature compared with that of pristine bulk AgI. Furthermore, a large conductivity hysteresis and abnormal conductivity transitions were observed in the temperature-dependent conductivity measurements, from which an ionic conductivity as high as 8.0 × 102 Ω-1 cm-1 was obtained at around 70 °C upon cooling. The differential scanning calorimetry (DSC) result demonstrates a similar phase transition behavior as that found in the AC conductivity measurements. The enhanced ionic conductivity, as well as the abnormal phase transitions, can be explained in terms of the existence of the highly conducting 7H polytype AgI and the formation of well-defined conduction paths in the composites.

  7. Agreement among ASES members on the AAOS Clinical Practice Guidelines.

    PubMed

    Paxton, E Scott; Matzon, Jonas L; Narzikul, Alexa C; Beredjiklian, Pedro K; Abboud, Joseph A

    2015-03-01

    The American Academy of Orthopaedic Surgeons (AAOS) has recently developed several clinical practice guidelines (CPG) involving upper extremity conditions. The purpose of the current study was to evaluate the practice patterns of members of the American Shoulder and Elbow Society (ASES) with regard to the CPGs. An e-mail survey was sent to the 340 members of the ASES. The survey contained 40 questions involving the subject matter of the 2 existing AAOS CPGs pertaining specifically to the shoulder: Optimizing the Management of Rotator Cuff Problems and the Treatment of Glenohumeral Joint Arthritis. Overall, 98 responses were obtained, for a response rate of 29%. Only 19 of 47 CPGs were not "inconclusive" and a recommendation was actually made. A majority (more than 50%) of surgeons agreed with 17 (90%) of 19 of these AAOS recommendations. A strong majority (more than 80%) adhered to 13 (68%) of 19 recommendations. There were 4 consensus recommendations, and more than 50% agreed with all of them. Of the 5 moderate recommendations, more than 50% agreed with 4 of them. There were 10 weak recommendations, and more than 50% of surgeons agreed with 9 of them. There was more than 80% agreement on 18 of 28 inconclusive recommendations. Although the AAOS CPGs are not meant to be fixed protocols, they are intended to unify treatment and/or diagnosis of common problems based on the best evidence available. Despite the majority of the AAOS CPG recommendations for rotator cuff problems and glenohumeral arthritis being inconclusive, most surgeons agree with most of the CPG recommendations.

  8. Effects of beta-escin and saponin on the transverse-tubular system and sarcoplasmic reticulum membranes of rat and toad skeletal muscle.

    PubMed

    Launikonis, B S; Stephenson, D G

    1999-05-01

    Mechanically skinned skeletal muscle fibres from rat and toad were exposed to the permeabilizing agents beta-escin and saponin. The effects of these agents on the sealed transverse tubular system (t-system) and sarcoplasmic reticulum (SR) were examined by looking at changes in the magnitude of the force responses to t-system depolarization, the time course of the fluorescence of fura-2 trapped in the sealed t-system, and changes in the magnitude of caffeine-induced contractures following SR loading with Ca2+ under defined conditions. In the presence of 2 microg ml-1 beta-escin and saponin, the response to t-system depolarization was not completely abolished, decreasing to a plateau, and a large proportion of fura-2 remained in the sealed t-system. At 10 microg ml-1, both agents abolished the ability of both rat and toad preparations to respond to t-system depolarization after 3 min of exposure, but a significant amount of fura-2 remained in sealed t-tubules even after exposure to 100 microg ml-1 beta-escin and saponin for 10 min. beta-Escin took longer than saponin to reduce the t-system depolarizations and fura-2 content of the sealed t-system to a similar level. The ability of the SR to load Ca2+ was reduced to a lower level after treatment with beta-escin than saponin. This direct effect on the SR occurred at much lower concentrations for rat (2 microg ml-1 beta-escin and 10 microg ml-1 saponin) than toad (10 microg ml-1 beta-escin and 150 microg ml-1 saponin). The reverse order in sensitivities to beta-escin and saponin of t-system and SR membranes indicates that the mechanisms of action of beta-escin and saponin are different in the two types of membrane. In conclusion, this study shows that: (1) beta-escin has a milder action on the surface membrane than saponin; (2) beta-escin is a more potent modifier of SR function; (3) simple permeabilization of membranes is not sufficient to explain the effects of beta-escin and saponin on muscle membranes; and (4) the t

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

    PubMed Central

    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. DOI: http://dx.doi.org/10.7554/eLife.18605.001 PMID:27619977

  10. Papillary tubular adenoma with marked tubular vacuolization.

    PubMed

    Hattori, N; Imakado, S; Kikuchi, K; Murakami, T; Furue, M

    1997-12-01

    We report a case of papillary tubular adenoma, arising on the knee joint. The overall histologic structure of the tumor is consistent with that of papillary tubular adenoma with slight interluminal papillary changes, but most of the tumor cells present vacuolization outlined by carcinoembryonic antigen staining, suggesting that this adenoma may have resulted from microlumen formation. This is, to our knowledge, the first reported case of a papillary tubular adenoma with marked tubular vacuolization.

  11. 30-MM Tubular Projectile

    DTIC Science & Technology

    1984-10-01

    Suiza tubular projectile 20 9. Inspection of Hispano Suiza sabot 21 10. Inspection of GAU-8 sabot 22 11. Firing data - 30-rn tubular projectile (Hispano... Suiza 23 copper banded) 12. Firing data - 30-m tubular projectile (GAU-8 plastic 24 banded) 13. Firing data - 30-m tubular projectile (GAU-8 copper 25...42 13. In-flight Hispano Suiza tubular projectiles 43 14. In-flight C4U-8 (plastic) tubular projectile 44 15. In-flight GCU-8 (copper) tubular

  12. 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.

  13. Platinum-modified SiO2 with tubular morphology as efficient membrane-type microreactors for mineralization of formic acid

    NASA Astrophysics Data System (ADS)

    Anastasescu, Crina; Anastasescu, Mihai; Zaharescu, Maria; Balint, Ioan

    2012-10-01

    SiO2 amorphous tubes with the internal diameter ranging between 5 and 170 nm and having the aspect ratios typically >50, were prepared using DL-tartaric acid as inorganic template. The tubular SiO2 was impregnated with a platinum precursor (H2PtCl6), dried and then reduced with H2. The TEM, XPS, FTIR characterization methods revealed that platinum species were located preferentially on the inner walls of tubes having diameter smaller than 100 nm. The walls of SiO2 nanotubes proved to be amorphous and highly porous, the diameter of pores covering a wide range of radii. The macroporosity of the SiO2 tubes originated from the open ends of the tubes with the diameter ≥100 nm, whereas the pores located in the walls of tubes were responsible for the meso and microporosity. Finer Pt nanoparticles (0.9 nm average size) were obtained after the catalyst was dried in air in mild conditions compared to the catalytic material reduced with H2 (5.3 nm mean size) According to FTIR results, strong metal-support interaction was evidenced between platinum nanoparticles and inner walls of SiO2 nanotubes. In order to observe the effect of Pt nanoparticle morphology on catalytic behavior, the activity of platinum-modified SiO2 tubes (1 wt% Pt/SiO2) for the oxidation of formic acid to CO2 was investigated in the 20-75 °C temperature range. The catalytic activity-morphology relationship of Pt/SiO2 nanotubes was studied and the results were explained in light of experimental results. The catalytic experiments revealed for the first time that SiO2 nanotubes with highly permeable walls behave as efficient membrane-type microreactors for the oxidation of formic acid to CO2. This type of morphological-dependent catalysis may prove to be an efficient tool in near future for the abatement of pollutants in liquid phase.

  14. Role of Operon aaoSo-mutT in Antioxidant Defense in Streptococcus oligofermentans

    PubMed Central

    Zhou, Peng; Liu, Lei; Tong, Huichun; Dong, Xiuzhu

    2012-01-01

    Previously, we have found that an insertional inactivation of aaoSo, a gene encoding L-amino acid oxidase (LAAO), causes marked repression of the growth of Streptococcus oligofermentans. Here, we found that aaoSo and mutT, a homolog of pyrophosphohydrolase gene of Escherichia coli, constituted an operon. Deletion of either gene did not impair the growth of S. oligofermentans, but double deletion of both aaoSo and mutT was lethal. Quantitative PCR showed that the transcript abundance of mutT was reduced for 13-fold in the aaoSo insertional mutant, indicating that gene polarity derived from the inactivation of aaoSo attenuated the expression of mutT. Enzymatic assays were conducted to determine the biochemical functions of LAAO and MutT of S. oligofermentans. The results indicated that LAAO functioned as an aminoacetone oxidase [47.75 nmol H2O2 (min·mg protein)–1]; and MutT showed the pyrophosphohydrolase activity, which removed mutagens such as 8-oxo-dGTP. Like paraquat, aaoSo mutations increased the expression of SOD, and addition of aminoacetone (final concentration, 5 mM) decreased the mutant’s growth by 11%, indicating that the aaoSo mutants are under ROS stress. HPLC did reveal elevated levels of cytoplasmic aminoacetone in both the deletion and insertional gene mutants of aaoSo. Electron spin resonance spectroscopy showed increased hydroxyl radicals in both types of aaoSo mutant. This demonstrated that inactivation of aaoSo caused the elevation of the prooxidant aminoacetone, resulting the cellular ROS stress. Our study indicates that the presence of both LAAO and MutT can prevent endogenous metabolites-generated ROS and mutagens. In this way, we were able to determine the role of the aaoSo-mutT operon in antioxidant defense in S. oligofermentans. PMID:22666463

  15. 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.

  16. 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.

  17. 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

  18. Nanoporous AAO: A platform for regular heterogeneous nanostructures and energy storage devices

    NASA Astrophysics Data System (ADS)

    Perez, Israel

    Nanoporous anodic aluminum oxide (AAO) has vast implications as a tool for nanoscience research and as a nanostructure in which nanoscale devices can be fabricated because of its regular and ordered nanopores. Self-assembly plays a critical role in pore ordering, causing nanopores to grow parallel with one another in high density. The mild electrochemical conditions in which porous AAO grows along with its relatively cheap starting materials makes this nanomaterial a cost effective alternative to advanced photolithography techniques for forming high surface area nanostructures over large areas. In this research, atomic layer deposition (ALD) was used to deposit conformal films within in nanoporous AAO with hopes to (1) develop methodologies to characterize ALD depositions within its high aspect ratio nanopores and (2) to better understand how to use nanoporous AAO templates as a scaffold for energy devices, specifically Metal-Insulator-Metal (MIM) capacitors. Using the nanotube template synthesis method, ALD films were deposited onto nanoporous AAO, later removing the films deposited within the templates nanopores for characterization in TEM. This nanotube metrology characterization involves first obtaining images of full length ALD-AAO nanotubes, and then measuring wall thickness as a function of depth within the nanopore. MIM nanocapacitors were also constructed in vertical AAO nanopores by deposition of multilayer ALD films. MIM stacks were patterned into micro-scale capacitors for electrical characterization.

  19. SAMI: Sydney-AAO Multi-object Integral field spectrograph pipeline

    NASA Astrophysics Data System (ADS)

    Allen, J. T.; Green, A. W.; Fogarty, L. M. R.; Sharp, R.; Nielsen, J.; Konstantopoulos, I.; Taylor, E. N.; Scott, N.; Cortese, L.; Richards, S. N.; Croom, S.; Owers, M. S.; Bauer, A. E.; Sweet, S. M.; Bryant, J. J.

    2014-07-01

    The SAMI (Sydney-AAO Multi-object Integral field spectrograph) pipeline reduces data from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) for the SAMI Galaxy Survey. The python code organizes SAMI data and, along with the AAO 2dfdr package, carries out all steps in the data reduction, from raw data to fully calibrated datacubes. The principal steps are: data management, use of 2dfdr to produce row-stacked spectra, flux calibration, correction for telluric absorption, removal of atmospheric dispersion, alignment of dithered exposures, and drizzling onto a regular output grid. Variance and covariance information is tracked throughout the pipeline. Some quality control routines are also included.

  20. 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.

  1. 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.

  2. Effect of atomic layer deposition coatings on the surface structure of anodic aluminum oxide membranes.

    PubMed

    Xiong, Guang; Elam, Jeffrey W; Feng, Hao; Han, Catherine Y; Wang, Hsien-Hau; Iton, Lennox E; Curtiss, Larry A; Pellin, Michael J; Kung, Mayfair; Kung, Harold; Stair, Peter C

    2005-07-28

    Anodic aluminum oxide (AAO) membranes were characterized by UV Raman and FT-IR spectroscopies before and after coating the entire surface (including the interior pore walls) of the AAO membranes by atomic layer deposition (ALD). UV Raman reveals the presence of aluminum oxalate in bulk AAO, both before and after ALD coating with Al2O3, because of acid anion incorporation during the anodization process used to produce AAO membranes. The aluminum oxalate in AAO exhibits remarkable thermal stability, not totally decomposing in air until exposed to a temperature >900 degrees C. ALD was used to cover the surface of AAO with either Al2O3 or TiO2. Uncoated AAO have FT-IR spectra with two separate types of OH stretches that can be assigned to isolated OH groups and hydrogen-bonded surface OH groups, respectively. In contrast, AAO surfaces coated by ALD with Al2O3 display a single, broad band of hydrogen-bonded OH groups. AAO substrates coated with TiO2 show a more complicated behavior. UV Raman results show that very thin TiO2 coatings (1 nm) are not stable upon annealing to 500 degrees C. In contrast, thicker coatings can totally cover the contaminated alumina surface and are stable at temperatures in excess of 500 degrees C.

  3. Pore spanning lipid bilayers on silanised nanoporous alumina membranes

    NASA Astrophysics Data System (ADS)

    Md Jani, Abdul M.; Zhou, Jinwen; Nussio, Matthew R.; Losic, Dusan; Shapter, Joe G.; Voelcker, Nicolas H.

    2008-12-01

    The preparation of bilayer lipid membranes (BLMs) on solid surfaces is important for many studies probing various important biological phenomena including the cell barrier properties, ion-channels, biosensing, drug discovery and protein/ligand interactions. In this work we present new membrane platforms based on suspended BLMs on nanoporous anodic aluminium oxide (AAO) membranes. AAO membranes were prepared by electrochemical anodisation of aluminium foil in 0.3 M oxalic acid using a custom-built etching cell and applying voltage of 40 V, at 1oC. AAO membranes with controlled diameter of pores from 30 - 40 nm (top of membrane) and 60 -70 nm (bottom of membrane) were fabricated. Pore dimensions have been confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). AAO membranes were chemically functionalised with 3-aminopropyltriethoxysilane (APTES). Confirmation of the APTES attachment to the AAO membrane was achieved by means of infrared spectroscopy, X-ray photoelectron spectroscopy and contact angle measurements. The Fourier transform infrared (FTIR) spectra of functionalised membranes show several peaks from 2800 to 3000 cm-1 which were assigned to symmetric and antisymmetric CH2 bands. XPS data of the membrane showed a distinct increase in C1s (285 eV), N1s (402 eV) and Si2p (102 eV) peaks after silanisation. The water contact angle of the functionalised membrane was 80o as compared to 20o for the untreated membrane. The formation of BLMs comprising dioleoyl-phosphatidylserine (DOPS) on APTESmodified AAO membranes was carried using the vesicle spreading technique. AFM imaging and force spectroscopy was used to characterise the structural and nanomechanical properties of the suspended membrane. This technique also confirmed the stability of bilayers on the nanoporous alumina support for several days. Fabricated suspended BLMs on nanoporous AAO hold promise for the construction of biomimetic membrane architectures with embedded

  4. 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.

  5. Proximal renal tubular acidosis

    MedlinePlus

    ... References Krapf R, Seldin DW, Alpern RJ. Clinical syndromes of metabolic acidosis. In: Alpern RJ, Caplan M, Moe OW, ... 529. Read More Distal renal tubular acidosis Fanconi syndrome Low potassium level Metabolic acidosis Osteomalacia Respiratory acidosis Rickets Review Date 10/ ...

  6. Distal renal tubular acidosis

    MedlinePlus

    ... get better with treatment. When to Contact a Medical Professional Call your health care provider if you have symptoms of distal renal tubular acidosis. Get medical help right away if you develop emergency symptoms ...

  7. Renal tubular acidosis.

    PubMed

    Chan, J C

    1983-03-01

    In the past decade major advances in our understanding of renal tubular hydrogen ion secretion and bicarbonate reabsorption have provided new insight into the pathophysiology of renal tubular acidosis. Thus "fragment to fragment clings" and the number of disorders categorized within the syndrome grows, until we have come to know and name four types, with many subtypes. We hope this new perspective provides a basis for the physician to recognize renal tubular acidosis in its several forms so that an informed decision may be arrived at in choosing the best therapy. The physician may also be prepared to reasonably project the prognosis for each patient. We also hope that our detailed examination of renal acidification will provide a reference for delineation of new clinical expressions of acid-base disorders and kidney malfunction certain to be described in the years ahead.

  8. Separation of BSA through FAU-Type Zeolite Ceramic-Composite Membrane Formed on Tubular Ceramic Support: Optimization of Process Parameters by Hybrid Response Surface Methodology and Bi-Objective Genetic Algorithm.

    PubMed

    Kumar, R Vinoth; Moorthy, I Ganesh; Pugazhenthi, G

    2017-03-09

    In this study, Faujasite (FAU) zeolite was coated on low cost tubular ceramic support as a separating layer via hydrothermal route. The mixture of silicate and aluminate solutions was used to create a zeolitic separation layer on the support. The prepared zeolite ceramic-composite membrane was characterized by using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), particle size distribution (PSD), Field emission scanning electron microscopy (FESEM) and zeta potential measurements. The porosity of ceramic support (53%) was reduced by the deposition of FAU (43%) zeolite layer. The pore size and water permeability of the membrane were evaluated as 0.179 µm and 1.62 × 10(-7) m(3)/m(2)s.kPa, respectively, which are lower than that of the support (pore size of 0.309 µm and water permeability of 5.93 × 10(-7) m(3)/m(2)s.kPa). The permeate flux and rejection potential of the prepared membrane was evaluated by microfiltration of bovine serum albumin (BSA). To study the influences of three independent variables such as operating pressure (68.94 - 275.79 kPa), concentration of BSA (100 - 500 ppm) and solution pH (2 - 4) on permeate flux and percentage of rejection, the RSM (Response Surface Methodology) was employed. The predicted models for permeate flux and rejection were further subjected to bi-objective Genetic Algorithm (GA). The hybrid RSM-GA approach resulted a maximum permeate flux of 2.66 × 10(-5) m(3)/m(2)s and BSA rejection of 88.02%, at which the optimum conditions were attained as 100 ppm BSA concentration, 2 pH solution and 275.79 kPa applied pressure. In addition, the separation efficiency was compared with other membranes applied for BSA separation in order to know the potential of the fabricated FAU zeolite ceramic-composite membrane.

  9. Orthopedic surgery residents and the CDC and AAOS HIV precautionary measures.

    PubMed

    Hutchinson, S G; Delene, L M; Hutchinson, M R; Halpern, A A

    1996-03-01

    A randomized national survey of orthopedic surgery residents concerning their knowledge, attitudes, and behaviors of the Centers for Disease Control's and the American Academy of Orthopaedic Surgeons' (AAOS) universal human immunodeficiency virus (HIV) precautionary measures was conducted. The residents' basic knowledge about the HIV precautionary measures was, in general, poor. Thirty-seven percent indicated that they were "uncertain" or "would not" care for HIV positive patients. Further, the residents' practice behaviors in many instances did not fulfill prescribed universal precautions. Sound educational and professional programs, such as those initiated by the AAOS, are needed to increase the knowledge and improve the practice behaviors of orthopedic residents.

  10. [The enlarged diagnosis of the fatal penicillin accident. Immunehistologic demonstration of antigen-antibody complexes and of antibodies against the tubular basement membrane after administraiton of depot penicillin].

    PubMed

    Dirnhofer, R; Sonnabend, W; Sigrist, T

    1978-05-20

    In a case of fatal penicillin allergy it proved possible at autopsy to demonstrate (by immunohistological examination of basal membranes of proximal renal tubuli) antigen-antibody complexes belonging to the penicillin (BPO) group and to an anti-penicilloyl antibody of the IgG type. In addition, complement C3 was detected. Antibodies against the basal membranes or renal tubuli were also demonstrated in material eluted from the kidney, although an inflammatory reaction ot the immunoligical changes had not yet been observed in light microscopy. It is undecided whether this discrepancy is due to the low dose of penicillin administered or the relatively short time lag between first injection and time of fatality. It is assumed that, pathogenetically, a reaction of the serum sickness type is probably involved. For etiological clarification the use of immunohistological methods in addition to serological procedures provides further indices for an antecedent sensitization to penicillin, because assay effectiveness does not decrease even after a lengthy postmortal time-lapse. On the other hand, tissues and serum for examination should be frozen at low temperatures immediately after autopsy.

  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. Self-ordering behavior of nanoporous anodic aluminum oxide (AAO) in malonic acid anodization

    NASA Astrophysics Data System (ADS)

    Lee, W.; Nielsch, K.; Gösele, U.

    2007-11-01

    The self-ordering behavior of anodic aluminum oxide (AAO) has been investigated for anodization of aluminum in malonic acid (H4C3O4) solution. In the present study it is found that a porous oxide layer formed on the surface of aluminum can effectively suppress catastrophic local events (such as breakdown of the oxide film and plastic deformation of the aluminum substrate), and enables stable fast anodic oxidation under a high electric field of 110-140 V and ~100 mA cm-2. Studies on the self-ordering behavior of AAO indicated that the cell homogeneity of AAO increases dramatically as the anodization voltage gets higher than 120 V. Highly ordered AAO with a hexagonal arrangement of the nanopores could be obtained in a voltage range 125-140 V. The current density (i.e., the electric field strength (E) at the bottom of a pore) is an important parameter governing the self-ordering of the nanopores as well as the interpore distance (Dint) for a given anodization potential (U) during malonic acid anodization.

  13. Readability of online patient education materials from the AAOS web site.

    PubMed

    Sabharwal, Sanjeev; Badarudeen, Sameer; Unes Kunju, Shebna

    2008-05-01

    One of the goals of the American Academy of Orthopaedic Surgeons (AAOS) is to disseminate patient education materials that suit the readability skills of the patient population. According to standard guidelines from healthcare organizations, the readability of patient education materials should be no higher than the sixth-grade level. We hypothesized the readability level of patient education materials available on the AAOS Web site would be higher than the recommended grade level, regardless when the material was available online. Readability scores of all articles from the AAOS Internet-based patient information Web site, "Your Orthopaedic Connection," were determined using the Flesch-Kincaid grade formula. The mean Flesch-Kincaid grade level of the 426 unique articles was 10.43. Only 10 (2%) of the articles had the recommended readability level of sixth grade or lower. The readability of the articles did not change with time. Our findings suggest the majority of the patient education materials available on the AAOS Web site had readability scores that may be too difficult for comprehension by a substantial portion of the patient population.

  14. Readability of Online Patient Education Materials From the AAOS Web Site

    PubMed Central

    Badarudeen, Sameer; Unes Kunju, Shebna

    2008-01-01

    One of the goals of the American Academy of Orthopaedic Surgeons (AAOS) is to disseminate patient education materials that suit the readability skills of the patient population. According to standard guidelines from healthcare organizations, the readability of patient education materials should be no higher than the sixth-grade level. We hypothesized the readability level of patient education materials available on the AAOS Web site would be higher than the recommended grade level, regardless when the material was available online. Readability scores of all articles from the AAOS Internet-based patient information Web site, “Your Orthopaedic Connection,” were determined using the Flesch-Kincaid grade formula. The mean Flesch-Kincaid grade level of the 426 unique articles was 10.43. Only 10 (2%) of the articles had the recommended readability level of sixth grade or lower. The readability of the articles did not change with time. Our findings suggest the majority of the patient education materials available on the AAOS Web site had readability scores that may be too difficult for comprehension by a substantial portion of the patient population. PMID:18324452

  15. Growth and Magnetic characterization of 1D Permalloy Nanowires using self developed AAO Templates

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Khan, G. G.; Das, B.; Mandal, K.

    2015-02-01

    1D Permalloy refers to an alloy of Ni and Fe with 80% and 20% composition respectively. 1D Permalloy nanowires are particularly attractive because of their high permeability, low coercivity, near zero magnetostriction and high anisotropic magnetoresistance. Because of low magnetostriction of Permalloy shape anisotropy plays a very important role. As a result, the nanowires show unidirectional anisotropy along their length. Because of this property, they can be used in many applications such as recording head sensors, magnetic storage devices etc. In the present work 1D Permalloy nanowires arrays were fabricated into the pores of self engineered Anodic Aluminium Oxide (AAO) templates by a simple electrodeposition technique (EDT). By varying the Anodization voltage and the parameters of the electrolytic solutions we developed various AAO templates with different average pore diameters. We developed the 1D Permalloy NW's of different diameters depending on the pore size arrangement of AAO templates by varying the deposition conditions. Structural characterization of AAO templates and 1D Permalloy NW's was performed by Transmission and Scanning Electron Microscopy (TEM & SEM). XRD studies of 1D Permalloy NW's shows their fcc crystalline structure and the AAO template was found to be amorphous in nature. Magnetic studies show the 1D Permalloy NW's arrays to have obvious anisotropy, and the easy axis was found to be parallel to the nanowires axis. We performed the angular dependence measurement of 1D Permalloy NW's. When the applied magnetic field was parallel to the nanowires, the coercivity (Hc) and the maximum remanent ratio (Mr/Ms) were considerably higher than those while the magnetic field perpendicular to the nanowires. 1D Permalloy NW's developed in this work are expected to be utilize in magnetic memory and magnetic recording devices.

  16. A NAP-AAO3 regulatory module promotes chlorophyll degradation via ABA biosynthesis in Arabidopsis leaves.

    PubMed

    Yang, Jiading; Worley, Eric; Udvardi, Michael

    2014-12-01

    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.

  17. Markers of tubular dysfunction.

    PubMed

    Piscator, M

    1989-03-01

    Since the first description of tubular proteinuria in 1958, much progress has been made with regard to diagnostic means for detecting small changes in the function of the proximal tubule. Small increases in the excretion of low-molecular-weight proteins can now be determined with great accuracy. Determination of total protein is an economic way of screening large populations but does not give specific information on the type of damage. Determinations of glucose, phosphate and amino acids are relatively insensitive methods, since their excretion is also dependent on diet and nutritional status. Determination of high-molecular-weight enzymes released from damaged tubular cells may be of use for studies of acute as well as chronic effects of nephrotoxic agents, but more data are needed.

  18. [Inherited tubular renal acidosis].

    PubMed

    Bouzidi, Hassan; Hayek, Donia; Nasr, Dhekra; Daudon, Michel; Fadhel Najjar, Mohamed

    2011-01-01

    Renal tubular acidosis (RTA) is a tubulopathy characterized by metabolic acidosis with normal anion gap secondary to abnormalities of renal acidification. RTA can be classified into four main subtypes: distal RTA, proximal RTA, combined proximal and distal RTA, and hyperkalemic RTA. Distal RTA (type 1) is caused by the defect of H(+) secretion in the distal tubules and is characterized by the inability to acidify the urine below pH 5.5 during systemic acidemia. Proximal RTA (type 2) is caused by an impairment of bicarbonate reabsorption in the proximal tubules and characterized by a decreased renal bicarbonate threshold. Combined proximal and distal RTA (type 3) secondary to a reduction in tubular reclamation of bicarbonate and an inability to acidify the urine in the face of severe acidemia. Hyperkalemic RTA (type 4) may occur as a result of aldosterone deficiency or tubular insensitivity to aldosterone. Clinicians should be alert to the presence of RTA in patients with an unexplained normal anion gap acidosis, hypokalemia, recurrent nephrolithiasis and nephrocalcinosis. The mainstay of treatment of RTA remains alkali replacement.

  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. 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.

  1. 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.

  2. Urinary proteins of tubular origin: basic immunochemical and clinical aspects.

    PubMed

    Scherberich, J E

    1990-01-01

    A variety of tubular marker proteins, as compared to healthy controls, are excreted at an increased rate in the urine of patients with renal damage. Beside cytoplasmic glutathione-S-transferase and lysosomal beta-N-acetyl-glucosaminidase (beta-NAG) the majority of kidney-related urine proteins derives from membrane surface components of the most vulnerable proximal tubule epithelia, among them ala-(leu-gly)-aminopeptidase, gamma-glutamyl transpeptidase (GGT), the tubular portion of angiotensinase A, the major brush border glycoprotein 'SGP-240' and adenosine-deaminase-binding protein. Urinary tissue proteins, e.g. brush border (BB) microvilli, are immunologically identical with those antigens prepared from cell membranes of the human kidney itself. BB antigens are shed into the urine of patients with glomerulonephritis, interstitial nephritis, systemic diseases, e.g. systemic lupus erythematosus (SLE), diabetes mellitus and multiple myeloma, arterial hypertension, infectious diseases (malaria, AIDS) and after operations, renal grafting and administration of X-ray contrast media, aminoglycosides or certain cytostatics (cis-platinum). Tissue proteinuria of tubular proteins is determined by enzyme-kinetic or quantitative immunological assays applying either poly- or monoclonal antikidney antibodies. Clinical, ultrastructural and histochemical studies support the idea that both 'soluble' and high-molecular-weight membrane particles (vacuolar blebs, greater than 10(6) dalton) as well as microfilamental components of the epithelial cytoskeleton contribute to tubular 'histuria' which appears as a sensitive parameter in monitoring tubular damage under clinical conditions at a very early phase.

  3. [Tubular renal acidosis].

    PubMed

    Seidowsky, A; Moulonguet-Doleris, L; Hanslik, T; Yattara, H; Ayari, H; Rouveix, E; Massy, Z A; Prinseau, J

    2014-01-01

    Renal tubular acidosis (RTAs) are a group of metabolic disorders characterized by metabolic acidosis with normal plasma anion gap. There are three main forms of RTA: a proximal RTA called type II and a distal RTA (type I and IV). The RTA type II is a consequence of the inability of the proximal tubule to reabsorb bicarbonate. The distal RTA is associated with the inability to excrete the daily acid load and may be associated with hyperkalaemia (type IV) or hypokalemia (type I). The most common etiology of RTA type IV is the hypoaldosteronism. The RTAs can be complicated by nephrocalcinosis and obstructive nephrolithiasis. Alkalinization is the cornerstone of treatment.

  4. 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.

  5. The Readability of AAOS Patient Education Materials: Evaluating the Progress Since 2008.

    PubMed

    Roberts, Heather; Zhang, Dafang; Dyer, George S M

    2016-09-07

    The Internet has become a major resource for patients; however, patient education materials are frequently written at relatively high levels of reading ability. The purpose of this study was to evaluate the readability of patient education materials on the American Academy of Orthopaedic Surgeons (AAOS) web site. Readability scores were calculated for all patient education articles on the AAOS web site using 5 algorithms: Flesch Reading Ease, Flesch-Kincaid Grade Level, SMOG (Simple Measure of Gobbledygook) Grade, Coleman-Liau Index, and Gunning-Fog Index. The mean readability scores were compared across the anatomic categories to which they pertained. Using a liberal measure of readability, the Flesch-Kincaid Grade Level, 3.9% of articles were written at or below the recommended sixth-grade reading level, and 84% of the articles were written above the eighth-grade reading level. Articles in the present study had a lower mean Flesch-Kincaid Grade Level than those available in 2008 (p < 0.00005). Articles categorized as "Hand & Wrist" or "Foot & Ankle" had significantly lower mean Flesch-Kincaid Grade Level scores than the mean for all categories (p < 0.0005). Regardless of the algorithm used, the mean readability levels of AAOS articles are higher than generally recommended. Although the mean Flesch-Kincaid Grade Level was lower in the present study than it was in 2008, a need remains to improve the readability of AAOS patient education articles. Ensuring that online patient education materials are written at an appropriate reading grade level would be expected to improve physician-patient communication. Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.

  6. Factors influencing publication of abstracts presented at the AAO-HNS Annual Meeting.

    PubMed

    Peng, Phyllis H; Wasserman, Jared M; Rosenfeld, Richard M

    2006-08-01

    To examine abstracts presented at the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Annual Meeting and to identify factors associated with publication success. All abstracts published in the August 1999 official program issue of the AAO-HNS Journal were examined. MEDLINE searches were performed to assess publication success. Multivariate analysis was performed to identify factors related to successful publication. We identified 473 abstracts, of which 260 (55%) were poster presentations. Median publication time was 16 months, with a publication rate of 50%. Multivariate analysis revealed oral presentation, statistical analysis, and number of authors to be the most significant predictive factors of publication success (odds ratios of 2.2, 1.9, and 1.2 respectively). Level of evidence did not correlate with publication success, even when case reports (n = 70) were excluded from the analysis. Publication rates in other disciplines ranged from 25% to 68%, with a mean of 47%. The rate of publication from the AAO-HNS Annual Meeting is similar to other disciplines. Oral presentations with inferential statistics in the abstract were most likely to be published. Conversely, level of evidence and direction of study inquiry were not significant predictors, suggesting that research design is a less important determinant of publication success. Our investigation is one of the first to critically analyze the factors in presentations at annual meetings that predict successful publication.

  7. Highly sensitive and scalable AAO-based nano-fibre SERS substrate for sensing application

    NASA Astrophysics Data System (ADS)

    Lim, L. K.; Ng, B. K.; Fu, C. Y.; Tobing, Landobasa Y. M.; Zhang, D. H.

    2017-06-01

    Well-ordered periodic nanostructures are excellent substrates for many surface-enhanced Raman spectroscopy (SERS) applications. Conventional fabrication approaches such as high precision electron beam lithography or focused ion beam produce high resolution nano-features with great reproducibility at the expense of low throughput. In this work, a highly sensitive and scalable AAO-nano-fibre (ANF) SERS substrate is demonstrated by optimising the second anodisation time of the standard two-step anodisation of aluminium and performing an additional wet etching step on the resulting AAO substrate. The optimised ANF substrate exhibits SERS sensitivity that surpasses the AAO nanoholes and the metal-film-on-nanoparticles substrates. A detection limit of 0.1 nM is achieved with a signal-to-noise ratio of 2.6-3 using a low excitation power of 0.1 mW. The ANF substrate exhibits an enhancement factor of 9.28 × 106 and a standard deviation of no more than 8%. The results indicate that the highly sensitive and scalable ANF substrate is a promising substrate for commercial SERS application.

  8. Fabrication of vertically aligned Pd nanowire array in AAO template by electrodeposition using neutral electrolyte

    PubMed Central

    2010-01-01

    A vertically aligned Pd nanowire array was successfully fabricated on an Au/Ti substrate using an anodic aluminum oxide (AAO) template by a direct voltage electrodeposition method at room temperature using diluted neutral electrolyte. The fabrication of Pd nanowires was controlled by analyzing the current–time transient during electrodeposition using potentiostat. The AAO template and the Pd nanowires were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) methods and X-Ray diffraction (XRD). It was observed that the Pd nanowire array was standing freely on an Au-coated Ti substrate after removing the AAO template in a relatively large area of about 5 cm2, approximately 50 nm in diameter and 2.5 μm in length with a high aspect ratio. The nucleation rate and the number of atoms in the critical nucleus were determined from the analysis of current transients. Pd nuclei density was calculated as 3.55 × 108 cm−2. Usage of diluted neutral electrolyte enables slower growing of Pd nanowires owing to increase in the electrodeposition potential and thus obtained Pd nanowires have higher crystallinity with lower dislocations. In fact, this high crystallinity of Pd nanowires provides them positive effect for sensor performances especially. PMID:20596417

  9. Characterisation of human tubular cell monolayers as a model of proximal tubular xenobiotic handling

    SciTech Connect

    Brown, Colin D.A. Sayer, Rachel; Windass, Amy S.; Haslam, Iain S.; Broe, Marc E. de; D'Haese, Patrick C.; Verhulst, Anja

    2008-12-15

    The aim of this study was to determine whether primary human tubular cell monolayers could provide a powerful tool with which to investigate the renal proximal tubular handling of xenobiotics. Human proximal and distal tubule/collecting duct cells were grown as monolayers on permeable filter supports. After 10 days in culture, proximal tubule cells remained differentiated and expressed a wide palette of transporters at the mRNA level including NaPi-IIa, SGLT1, SGLT2, OCT2, OCTN2, OAT1, OAT3, OAT4, MDR1, MRP2 and BCRP. At the protein level, the expression of a subset of transporters including NaPi-IIa, OAT1 and OAT3 was demonstrated using immunohistochemistry. Analysis of the expression of the ATP binding cassette efflux pumps MDR1, MRP2 and BCRP confirmed their apical membrane localisation. At the functional level, tubule cell monolayers retain the necessary machinery to mediate the net secretion of the prototypic substrates; PAH and creatinine. PAH secretion across the monolayer consisted of the uptake of PAH across the basolateral membrane by OAT1 and OAT3 and the apical exit of PAH by a probenecid and MK571-sensitive route consistent with actions of MRP2 or MRP4. Creatinine secretion was by OCT2-mediated uptake at the basolateral membrane and via MDR1 at the apical membrane. Functional expression of MDR1 and BCRP at the apical membrane was also demonstrated using a Hoechst 33342 dye. Similarly, measurement of calcein efflux demonstrated the functional expression of MRP2 at the apical membrane of cell monolayers. In conclusion, human tubular cell monolayers provide a powerful tool to investigate renal xenobiotic handling.

  10. Facile design of ultra-thin anodic aluminum oxide membranes for the fabrication of plasmonic nanoarrays

    NASA Astrophysics Data System (ADS)

    Hao, Qi; Huang, Hao; Fan, Xingce; Hou, Xiangyu; Yin, Yin; Li, Wan; Si, Lifang; Nan, Haiyan; Wang, Huaiyu; Mei, Yongfeng; Qiu, Teng; Chu, Paul K.

    2017-03-01

    Ultra-thin anodic aluminum oxide (AAO) membranes are efficient templates for the fabrication of patterned nanostructures. Herein, a three-step etching method to control the morphology of AAO is described. The morphological evolution of the AAO during phosphoric acid etching is systematically investigated and a nonlinear growth mechanism during unsteady-state anodization is revealed. The thickness of the AAO can be quantitatively controlled from ˜100 nm to several micrometers while maintaining the tunablity of the pore diameter. The AAO membranes are robust and readily transferable to different types of substrates to prepare patterned plasmonic nanoarrays such as nanoislands, nanoclusters, ultra-small nanodots, and core-satellite superstructures. The localized surface plasmon resonance from these nanostructures can be easily tuned by adjusting the morphology of the AAO template. The custom AAO template provides a platform for the fabrication of low-cost and large-scale functional nanoarrays suitable for fundamental studies as well as applications including biochemical sensing, imaging, photocatalysis, and photovoltaics.

  11. Facile design of ultra-thin anodic aluminum oxide membranes for the fabrication of plasmonic nanoarrays.

    PubMed

    Hao, Qi; Huang, Hao; Fan, Xingce; Hou, Xiangyu; Yin, Yin; Li, Wan; Si, Lifang; Nan, Haiyan; Wang, Huaiyu; Mei, Yongfeng; Qiu, Teng; Chu, Paul K

    2017-03-10

    Ultra-thin anodic aluminum oxide (AAO) membranes are efficient templates for the fabrication of patterned nanostructures. Herein, a three-step etching method to control the morphology of AAO is described. The morphological evolution of the AAO during phosphoric acid etching is systematically investigated and a nonlinear growth mechanism during unsteady-state anodization is revealed. The thickness of the AAO can be quantitatively controlled from ∼100 nm to several micrometers while maintaining the tunablity of the pore diameter. The AAO membranes are robust and readily transferable to different types of substrates to prepare patterned plasmonic nanoarrays such as nanoislands, nanoclusters, ultra-small nanodots, and core-satellite superstructures. The localized surface plasmon resonance from these nanostructures can be easily tuned by adjusting the morphology of the AAO template. The custom AAO template provides a platform for the fabrication of low-cost and large-scale functional nanoarrays suitable for fundamental studies as well as applications including biochemical sensing, imaging, photocatalysis, and photovoltaics.

  12. 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.

  13. 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.

  14. 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.

  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.

  16. Renal tubular acidosis.

    PubMed

    Rothstein, M; Obialo, C; Hruska, K A

    1990-12-01

    Renal tubular acidosis refers to a group of disorders that result from pure tubular damage without concomitant glomerular damage. They could be hereditary (primary) or acquired (secondary to various disease states like sickle cell disease, obstructive uropathy, postrenal transplant, autoimmune disease, or drugs). The hallmark of the disorder is the presence of hyperchloremic metabolic acidosis with, or without, associated defects in potassium homeostasis, a UpH greater than 5.5 in the presence of systemic acidemia, and absence of an easily identifiable cause of the acidemia. There are three physiologic types whose basic defects are impairment of or a decrease in acid excretion, i.e., type 1 (dRTA); a failure in bicarbonate reabsorption, i.e., type 2 (pRTA); and deficiency of buffer or impaired generation of NH4+, i.e., type 4 RTA. Several pathophysiologic mechanisms have been postulated for these various types. pRTA is the least common of all in the adult population. It rarely occurs as an isolated defect. It is frequently accompanied by diffuse proximal tubule transport defects with aminoaciduria, glycosuria, hyperphosphaturia, and so forth (Fanconi syndrome). dRTA is associated with a high incidence of nephrolithiasis, nephrocalcinosis, osteodystrophy, and growth retardation (in children). Osteodystrophy also occurs in pRTA to a lesser degree and is believed to be secondary to hypophosphatemia. Patients with type 4 RTA usually have mild renal insufficiency from either diabetes mellitus or interstitial nephritis. Acute bicarbonate loading will result in a high fractional excretion of bicarbonate greater than 15% (FEHCO3- greater than 15%) in patients with pRTA, but FEHCO3- less than 3% in patients with dRTA. Type I patients will also have a low (U - B) PCO2 with bicarbonate loading. They are also unable to lower their urine pH to less than 5.5 with NH4Cl loading. The treatment of these patients involves avoidance of precipitating factors when possible, treatment

  17. A study of adherence to the AAO-HNS "Clinical Practice Guideline: Adult Sinusitis".

    PubMed

    Darrat, Ilaaf; Yaremchuk, Kathleen; Payne, Spencer; Nelson, Michelle

    2014-08-01

    A retrospective study was conducted to determine if physicians in otolaryngology practice adhered to the clinical practice guideline for adult sinusitis that had been issued by the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) 3 years earlier. We analyzed data obtained from the charts of 90 adults who had presented to an otolaryngology outpatient department with a diagnosis of chronic rhinosinusitis (CRS), acute bacterial rhinosinusitis (ABRS), or acute viral rhinosinusitis (AVRS); there were 76 cases of CRS, 11 cases of ABRS, and 3 cases of AVRS. Our goal was to ascertain how closely the treating physician had adhered to the AAO-HNS recommendations with respect to diagnosis, treatment, and prevention of these diseases. The study group was made up of 10 otolaryngologists. We evaluated 7 clinical practice metrics for CRS, 7 metrics for ABRS, and 3 for AVRS. We found that individual physician adherence rates for cases of CRS ranged from 0 to 100%; average scores for the 7 metrics ranged from 4 to 88%. For cases of ABRS, adherence scores ranged from 0 to 100%; average scores for the 7 metrics ranged from 0 to 41%. For AVRS, the rate of adherence for all 3 metrics was 0%. This study revealed wide variations in adherence to the AAO-HNS guideline, but overall adherence was generally poor. Adherence appeared to be worse for the acute types of rhinosinusitis than for chronic rhinosinusitis. In view of these findings, a worksheet was developed that clinicians could use to improve compliance with the guidelines.

  18. Reconciling the clinical practice guidelines on Bell's palsy from the AAO-HNSF and the AAN.

    PubMed

    Schwartz, Seth R; Jones, Stephanie L; Getchius, Thomas S D; Gronseth, Gary S

    2014-05-01

    Bell's palsy, named after the Scottish anatomist, Sir Charles Bell, is the most common acute mononeuropathy, or disorder affecting a single nerve, and is the most common diagnosis associated with facial nerve weakness/paralysis. In the past 2 years, both the American Academy of Neurology (AAN) and the American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) have published clinical practice guidelines aimed to improve the quality of care and outcomes for patients diagnosed with Bell's palsy. This commentary aims to address the similarities and differences in the scope and final recommendations made by each guideline development group.

  19. Tubular organ epithelialisation

    PubMed Central

    Saksena, Rhea; Gao, Chuanyu; Wicox, Mathew; de Mel, Achala

    2016-01-01

    Hollow, tubular organs including oesophagus, trachea, stomach, intestine, bladder and urethra may require repair or replacement due to disease. Current treatment is considered an unmet clinical need, and tissue engineering strategies aim to overcome these by fabricating synthetic constructs as tissue replacements. Smart, functionalised synthetic materials can act as a scaffold base of an organ and multiple cell types, including stem cells can be used to repopulate these scaffolds to replace or repair the damaged or diseased organs. Epithelial cells have not yet completely shown to have efficacious cell–scaffold interactions or good functionality in artificial organs, thus limiting the success of tissue-engineered grafts. Epithelial cells play an essential part of respective organs to maintain their function. Without successful epithelialisation, hollow organs are liable to stenosis, collapse, extensive fibrosis and infection that limit patency. It is clear that the source of cells and physicochemical properties of scaffolds determine the successful epithelialisation. This article presents a review of tissue engineering studies on oesophagus, trachea, stomach, small intestine, bladder and urethral constructs conducted to actualise epithelialised grafts. PMID:28228931

  20. Tubular organ epithelialisation.

    PubMed

    Saksena, Rhea; Gao, Chuanyu; Wicox, Mathew; de Mel, Achala

    2016-01-01

    Hollow, tubular organs including oesophagus, trachea, stomach, intestine, bladder and urethra may require repair or replacement due to disease. Current treatment is considered an unmet clinical need, and tissue engineering strategies aim to overcome these by fabricating synthetic constructs as tissue replacements. Smart, functionalised synthetic materials can act as a scaffold base of an organ and multiple cell types, including stem cells can be used to repopulate these scaffolds to replace or repair the damaged or diseased organs. Epithelial cells have not yet completely shown to have efficacious cell-scaffold interactions or good functionality in artificial organs, thus limiting the success of tissue-engineered grafts. Epithelial cells play an essential part of respective organs to maintain their function. Without successful epithelialisation, hollow organs are liable to stenosis, collapse, extensive fibrosis and infection that limit patency. It is clear that the source of cells and physicochemical properties of scaffolds determine the successful epithelialisation. This article presents a review of tissue engineering studies on oesophagus, trachea, stomach, small intestine, bladder and urethral constructs conducted to actualise epithelialised grafts.

  1. 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.

  2. Mars Life? - Microscopic Tubular Structures

    NASA Image and Video Library

    1996-08-09

    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. http://photojournal.jpl.nasa.gov/catalog/PIA00287

  3. 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.

  4. 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.

  5. Performance enhancement of pc-Si solar cells through combination of anti-reflection and light-trapping: Functions of AAO nano-grating

    NASA Astrophysics Data System (ADS)

    Wu, Lei; Zhang, Haiming; Qin, Feifei; Bai, Xiaogang; Ji, Ziye; Huang, Dan

    2017-02-01

    Anodic aluminium oxide (AAO) nanogratings are experimentally applied to polycrystalline silicon (pc-Si) solar cells at front surface to improve the light coupling. On the basis of the Fresnel Reflection Principle, the primary reflection loss can be reduced by multi-layer dielectric film with varing refactive index. And this multi-layer film is regarded as anti-reflection coating. An efficient light-trapping structure is significant in absorption enhancement of long wavelength band (around 900-1100 nm) for silicon solar cells. In this paper, we put AAO nanogratings on the front side of pc-Si solar cells to serve as anti-reflecting coating and light-trapping structure. The operation leads to light absorption enhancement eventually. Thanks to AAO nano-grating's structure parameters, the anti-reflecting and light-trapping effects are changeable. This is discussed in three aspects: AAO lattice period, AAO thickness and its pore diameter. Optical interaction between AAO nanograting and Ag electrodes is also discussed. We find an increase of short-circuit current density (1.32 mA/cm2) with SiNx:H/AAO complex coating. The relative power conversion efficiency obtains a growth about 2.2% points. Additionally, AAO nanogratings may facilitate carrier separation. This improves the performance of pc-Si solar cells in electrical aspect.

  6. 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.

  7. Renal tubular function in hyperparathyroidism.

    PubMed Central

    van 't Hoff, W.; Bicknell, E. J.

    1989-01-01

    Renal tubular function was assessed in a group of patients with mild hyperparathyroidism before and after a mean period of 2.7 years conservative management. It was also assessed, before and after a mean of 3.3 years following surgery in a group of patients with initially higher plasma calcium concentration. Mean maximum urine osmolality was within the accepted range as was the maximum urine plasma hydrogen ion gradient in both groups at the time of diagnosis. No significant change in renal tubular function was observed in either group over the periods of this study. Although deterioration after a long period cannot be excluded, we do not consider that regular assessment of renal tubular function is necessary in the conservative management of primary hyperparathyroidism. PMID:2616415

  8. Highlights from the Hill: AAO-HNS legislative briefing day on Capitol Hill: a nursing perspective.

    PubMed

    McKennis, Ann T

    2003-01-01

    It is a well-known fact that to promote an issue in the political arena, a coalition or group of people desiring the same thing has more power than a single entity. I have seen the results in my home state of Texas when the Nursing Legislative Coalition of which the Society of Otorhinolaryngology-Head and Neck Nurses (SOHN) is a member, the Texas Hospital Association, and the Texas Medical Association all work together to pass legislation. As Chair of the Government Relations Committee (GRC), it was with this in mind that I requested to attend the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Legislative Briefing Day in Washington, D.C. on March 11, 2003. Executive Director Sandra Schwartz and President Linda Miller Calandra were also in attendance. This article provides an overview and personal perspectives of this event.

  9. 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.

  10. The AaO as Building Block in the Coupling of Text Kinematics with the Resonating Structure of a Metaphor.

    ERIC Educational Resources Information Center

    Bierschenk, Bernhard; Bierschenk, Inger

    The Agent-action-Objective (AaO) axiom and the theory of rotational dynamics constitute the frame of reference for the study of the metaphor as instrument for the direct perception of events. The major hypothesis of this frame of reference refers to the event structure embedded in the ground of a metaphor. Since the ground is implicit in the…

  11. 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.

  12. Presentation and publication rates among women and men at AAO-HNS meetings.

    PubMed

    Cohen, Marc A; Mirza, Natasha; Dow, Kristel; Abboud, Soo Kim

    2012-01-01

    We attempted to assess the percentages of abstracts submitted to annual American Academy of Otolaryngology, Head and Neck Surgery (AAO-HNS) meetings from 2000 to 2004 by both women and men. We sought to determine the subsequent peer-reviewed overall publication rates for all submissions. We also studied trends of submission among female presenters and compared them to males. Cross-sectional study. Tertiary academic medical center. 2,463 total abstracts presented between 2000 and 2004 were searched in the computerized databases Medline and Pubmed in 2008. The published articles were examined by reviewers to assess publication rate, time to publication, gender of authorship and subspecialty of publication. 1,413 (57.35%) posters and 1,051 (42.65%) oral presentations were presented from 2000 to 2004. Of the 1,413 posters presented, 275 (19.46%) were presented by female first authors. The female first-author poster publication rate was 33.81%, while the male first-author poster publication rate was 36.99% (p = 0.353). Of 1,051 oral presentations, 154 (14.65%) were presented by female first authors. The male first-author oral presentation publication rate was 60.98%, while the female first-author oral presentation publication rate was 59.09% (p = 0.657). There were no statistical differences in time to publication for posters (p = 0.796) or oral presentations (p = 0.737) between the genders. The majority of female first-author submissions involved pediatric (29.94%) and general (17.88%) otolaryngology. While women are increasingly drawn to otolaryngology, they represented less than 20% of total submissions at the annual AAO-HNS meetings from 2000 to 2004. Women more commonly submit poster than oral presentations. The eventual publication rates of abstracts and the average time to publication of presentations are equal between the genders. Copyright © 2013 S. Karger AG, Basel.

  13. Utility of the AAOS Appropriate Use Criteria (AUC) for Pediatric Supracondylar Humerus Fractures in Clinical Practice.

    PubMed

    Ibrahim, Talal; Hegazy, Abdelsalam; Abulhail, Safa I S; Ghomrawi, Hassan M K

    2017-01-01

    The American Academy of Orthopaedic Surgeons (AAOS) recently developed an Appropriate Use Criteria (AUC) for pediatric supracondylar humerus fractures (PSHF). The AUC is intended to improve quality of care by informing surgeon decision making. The aim of our study was to cross-reference the management of operatively treated PSHF with the AAOS-published AUC. The AUC for PSHF include 220 patient scenarios, based on different combinations of 6 factors. For each patient scenario, 8 treatment options are evaluated as "appropriate," "maybe appropriate," and "rarely appropriate." We retrospectively reviewed the medical charts and radiographs of all operatively treated PSHF at our hospital from January 2013 to December 2014 and determined the appropriateness of the treatment. Over the study period, 94 children (mean age: 5.2 y; 51 male, 43 female) were admitted with PSHF and underwent a surgical procedure (type IIA: 7, type IIB: 14, type III: 70, flexion type: 3). Only 8 of the 220 scenarios were observed in our patient cohort. The most frequent scenario was represented by a type III fracture, palpable distal pulse, no nerve injury, closed soft-tissue envelope, no radius/ulna fracture, and typical swelling. Of the 94 fractures, the AUC was "appropriate" for 84 cases and "maybe appropriate" for 9 cases. There was only 1 case of "rarely appropriate" management. Closed reduction with lateral pinning and immobilization was the most prevalent treatment option (58.5%). The rate of appropriateness was not affected by the operating surgeon. However, the definition of a case as emergent had a significant impact on the rate of appropriateness. Application of the AUC to actual clinical data was relatively simple. The majority of operatively treated PSHF (89.4%) were managed appropriately. With the introduction of electronic medical charts, an AUC application becomes attractive and easy for orthopaedic surgeons to utilize in clinical practice. However, validity studies of the AUC in

  14. Responses of proximal tubular cells to injury in congenital renal disease: fight or flight.

    PubMed

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

    2014-04-01

    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 polycystic kidney and fibrosis (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 knockout 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.

  15. 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

  16. 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

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

    PubMed

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

    2011-03-15

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

  18. Mars Life? - Microscopic Tubular Structures

    NASA Image and Video Library

    1996-08-09

    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. http://photojournal.jpl.nasa.gov/catalog/PIA00285

  19. 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)

  20. METHOD OF FABRICATING TUBULAR UNITS

    DOEpatents

    Ohlinger, L.A.

    1961-06-20

    A process is described for making a fuel element comprising a tubular jacket and fuel slugs held by the jacket in longitudinally spaced relation to one another. The jacket is lengthened as a result of being drawn down to grip the fuel slugs. As an intentional incident to this operation, the fuel slugs become longitudinally spaced from one another.

  1. 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)

  2. AUTOLOGOUS IMMUNE COMPLEX NEPHRITIS INDUCED WITH RENAL TUBULAR ANTIGEN

    PubMed Central

    Glassock, Richard J.; Edgington, Thomas S.; Watson, J. Ian; Dixon, Frank J.

    1968-01-01

    The pathogenetic mechanism involved in a form of experimental allergic glomerulonephritis induced by immunization of rats with renal tubular antigen has been investigated. A single immunization with less than a milligram of a crude renal tubular preparation, probably containing less than 25 µg of the specific nephritogenic antigen, is effective in the induction of this form of chronic membranous glomerulonephritis. In the nephritic kidney autologous nephritogenic tubular antigen is found in the glomerular deposits along with γ-globulin and complement. When large amounts of antigen are injected during induction of the disease the exogenous immunizing antigen can also be detected in the glomerular deposits. It appears that this disease results from the formation of circulating antibodies capable of reacting with autologous renal tubular antigen(s) and the deposition of these antibodies and antigen(s) plus complement apparently as immune complexes in the glomeruli. This pathogenetic system has been termed an autologous immune complex disease and the resultant glomerulonephritis has been similarly designated. PMID:4169966

  3. Nonlinear Analysis of Bonded Composite Tubular Lap Joints

    NASA Technical Reports Server (NTRS)

    Oterkus, E.; Madenci, E.; Smeltzer, S. S., III; Ambur, D. R.

    2005-01-01

    The present study describes a semi-analytical solution method for predicting the geometrically nonlinear response of a bonded composite tubular single-lap joint subjected to general loading conditions. The transverse shear and normal stresses in the adhesive as well as membrane stress resultants and bending moments in the adherends are determined using this method. The method utilizes the principle of virtual work in conjunction with nonlinear thin-shell theory to model the adherends and a cylindrical shear lag model to represent the kinematics of the thin adhesive layer between the adherends. The kinematic boundary conditions are imposed by employing the Lagrange multiplier method. In the solution procedure, the displacement components for the tubular joint are approximated in terms of non-periodic and periodic B-Spline functions in the longitudinal and circumferential directions, respectively. The approach presented herein represents a rapid-solution alternative to the finite element method. The solution method was validated by comparison against a previously considered tubular single-lap joint. The steep variation of both peeling and shearing stresses near the adhesive edges was successfully captured. The applicability of the present method was also demonstrated by considering tubular bonded lap-joints subjected to pure bending and torsion.

  4. Nonlinear Analysis of Bonded Composite Tubular Lap Joints

    NASA Technical Reports Server (NTRS)

    Oterkus, E.; Madenci, E.; Smeltzer, S. S., III; Ambur, D. R.

    2005-01-01

    The present study describes a semi-analytical solution method for predicting the geometrically nonlinear response of a bonded composite tubular single-lap joint subjected to general loading conditions. The transverse shear and normal stresses in the adhesive as well as membrane stress resultants and bending moments in the adherends are determined using this method. The method utilizes the principle of virtual work in conjunction with nonlinear thin-shell theory to model the adherends and a cylindrical shear lag model to represent the kinematics of the thin adhesive layer between the adherends. The kinematic boundary conditions are imposed by employing the Lagrange multiplier method. In the solution procedure, the displacement components for the tubular joint are approximated in terms of non-periodic and periodic B-Spline functions in the longitudinal and circumferential directions, respectively. The approach presented herein represents a rapid-solution alternative to the finite element method. The solution method was validated by comparison against a previously considered tubular single-lap joint. The steep variation of both peeling and shearing stresses near the adhesive edges was successfully captured. The applicability of the present method was also demonstrated by considering tubular bonded lap-joints subjected to pure bending and torsion.

  5. Better understanding of tubular helical buckling

    SciTech Connect

    Wu, J.

    1996-09-01

    Tubular buckling is a significant problem within the oil industry. Although it has been studied for many years, methods to analyze tubular helical buckling continues to appear in the literature. Several criteria have been derived and presented leading to confusion in understanding and correctly predicting tubular helical buckling. The prediction of tubular helical buckling is complicated by the fact that the tubular is confined within the wellbore. The tubular initially buckles sinusoidally, and then changes into the shape of a helix (helical buckling) as the axial load increases. Different approaches in modeling the helical buckling process and the use of energy methods resulted in those different helical buckling criteria. Helical buckling criteria proposed in the literature, as well as their derivations are discussed in this paper, to help better understand and effectively predict tubular helical buckling in engineering operations.

  6. Electrodeposition of vertically standing Ag nanoplates and nanowires on transparent conductive electrode using porous anodic aluminum oxide membrane.

    PubMed

    Wang, Jue; Pan, Shanlin

    2017-08-14

    We report fabricating vertically standing Ag nanoplates and nanowires on top of a transparent conductive substrate of indium tin oxides (ITO) with the assistance of porous anodic aluminum oxide (AAO) membrane. Two-dimensional Ag nanoplates are electrodeposited onto ITO surface which is covered with an AAO membrane without using an adhesion layer. Ag nanoplates obtained using AAO membranes majorly present 3×{222} superlattice fringes, different from the 3×{422} superlattice fringes reported in the previous study. Ag nanowires can be electrodeposited onto ITO which is initially modified with a conductive polymer poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) followed by grafting AAO membrane to remove the gap. The coverage, diameter, and thickness of Ag nanoplates are strongly dependent on the electrodeposition time and the diameter of Ag nanowires is determined by the pore size of AAO membranes. These Ag nanoplates and nanowires are studied for applications in surface enhanced Raman spectroscopy (SERS) and the influence of their shape, size, and coverage on SERS enhancement is explored. © 2017 IOP Publishing Ltd.

  7. Early detection of tubular dysfunction.

    PubMed

    Piscator, M

    1991-11-01

    The determination of low-molecular-weight proteins in urine as a tool for early detection of damage to the proximal tubules is briefly discussed. Beta 2-microglobulin, retinol-binding protein and alpha 1-microglobulin are at present the most widely used markers for tubular dysfunction. The determination of beta 2-microglobulin has earlier been the method of choice, but due to its instability at low pH there are certain disadvantages. Available data indicate that alpha 1-microglobulin may replace beta 2-microglobulin for screening purposes. The low-molecular-weight proteins are at present the best markers for early detection of tubular dysfunction; other constituents are not as well suited for this, even if the determination of urine enzymes has its supporters.

  8. Flexible anodized aluminum oxide membranes with customizable back contact materials

    NASA Astrophysics Data System (ADS)

    Nadimpally, B.; Jarro, C. A.; Mangu, R.; Rajaputra, S.; Singh, V. P.

    2016-12-01

    Anodized aluminum oxide (AAO) membranes were fabricated using flexible substrate/carrier material. This method facilitates the use of AAO templates with many different materials as substrates that are otherwise incompatible with most anodization techniques. Thin titanium (Ti) and tungsten (W) layers were employed as interlayer materials. Titanium enhances adhesion. Tungsten not only helps eliminate the barrier layer but also plays a critical role in enabling the use of flexible substrates. The resulting flexible templates provide new, exciting opportunities in photovoltaic and other device applications. CuInSe2 nanowires were electrochemically deposited into porous AAO templates with molybdenum (Mo) as the back contact material. The feasibility of using any material to form a contact with semiconductor nanowires has been demonstrated for the first time enabling new avenues in photovoltaic applications.

  9. Plasmonic enhancement of blue emission from ZnO nanorods grown on the anodic aluminum oxide (AAO) template

    NASA Astrophysics Data System (ADS)

    Norek, Małgorzata; Łuka, Grzegorz; Godlewski, Marek; Płociński, Tomasz; Michalska-Domańska, Marta; Stępniowski, Wojciech J.

    2013-04-01

    Luminescent properties of ZnO nanorods covered with Ag nanoparticles are examined. Nanorods were synthesized on AAO templates using Atomic Layer Deposition (ALD) technique. Two types of the samples were prepared with different arrangement of ZnO nanorods and doping conditions. Nanorods of the second type were codoped with Al, to stimulate defect-related emissions. The ZnO material fills heterogeneously the interior of the AAO nanopores and has hexagonal, wurtzite structure. Both types of structures exhibit a broad defect-related emission at about 440 nm, most probably related to recombination at zinc interstitial (Zni) defects. This emission in samples with a random distribution of ZnO:Al nanorods and finer Ag nanoparticles is enhanced by factor of ˜2.5 upon Ag deposition. The so-obtained material is interesting from the point of view of its application in blue range emitting diodes.

  10. Preparation of AAO-CeO2 nanotubes and their application in electrochemical oxidation desulfurization of diesel.

    PubMed

    Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

    2017-02-10

    The coaxial arrays of AAO-CeO2 NTs have been successfully galvanostatically deposited on an anode, characterized and adopted as a catalyst for removing organic sulfurs from diesel. The influence of the main electrochemical oxidation factors on the efficiency of desulfurization have also been investigated. The results show that the fabrication process of AAO-CeO2 NTs is accompanied by the formation of a new phase, namely Al3Ce, and the main oxidation products of the diesel are soluble inorganic sulphides, especially Ce2(SO4)3. When compared with dibenzothiophene and 4, 6-dimethyldibenzothiophene, benzothiophene is much more easily removed, with a removal efficiency that reaches 87.2%. Finally, a possible electrochemical oxidation desulfurization pathway for diesel is proposed.

  11. Preparation of AAO-CeO2 nanotubes and their application in electrochemical oxidation desulfurization of diesel

    NASA Astrophysics Data System (ADS)

    Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

    2017-02-01

    The coaxial arrays of AAO-CeO2 NTs have been successfully galvanostatically deposited on an anode, characterized and adopted as a catalyst for removing organic sulfurs from diesel. The influence of the main electrochemical oxidation factors on the efficiency of desulfurization have also been investigated. The results show that the fabrication process of AAO-CeO2 NTs is accompanied by the formation of a new phase, namely Al3Ce, and the main oxidation products of the diesel are soluble inorganic sulphides, especially Ce2(SO4)3. When compared with dibenzothiophene and 4, 6-dimethyldibenzothiophene, benzothiophene is much more easily removed, with a removal efficiency that reaches 87.2%. Finally, a possible electrochemical oxidation desulfurization pathway for diesel is proposed.

  12. AC electrodeposition of NiMn alloy nanowires in AAO template

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    The ordered ferromagnetic-antiferromagnetic Ni(1-x)Mnx alloy nanowires were fabricated successfully by alternating current (AC) electrodeposition into nanoporous anodized aluminum oxide (AAO). The NiMn alloy nanowires were deposited in a simple sulfate bath. Effect of bath composition on Mn content of electrodeposited nanowires as well as the thermal annealing effect on magnetic properties were explored. The magnetic properties of NiMn alloy nanowires were enhanced significantly, compared to corresponding bulk materials. Magnetic parameters, such as coercivity and saturation magnetization were decreased with increasing the Mn content. For thermal annealing process, it was found that these parameters were enhanced with increasing the temperature up to 300∘C, on the other hand, they were decreased with increasing the temperature to 500∘C. Moreover, the X-ray diffraction (XRD) patterns revealed that the FCC crystalline structure of Ni turns to an amorphous phase by increasing the Mn content in the nanowires, resulting in a significant reduction in the Hc.

  13. The Completion and Release of the AAO/UKST Hα Survey

    NASA Astrophysics Data System (ADS)

    Parker, Q. A.; Phillipps, S.

    2003-05-01

    The AAO UK Schmidt Telescope (UKST) has just completed an Hα survey of the Southern Galactic Plane and Magellanic Clouds. The resultant map represents the last great photographic UKST survey product. A single-element interference filter of exceptional quality was used, the largest of its kind for astronomy. With fine-grained Tech-Pan film as the detector, an atlas with an unequalled combination of resolution, sensitivity and areal coverage has been created, superior to any equivalent optical line emission survey in our Galaxy. The Wide Field Astronomy Unit of the Institute for Astronomy Edinburgh hosts the survey data archive and is responsible for disseminating the data products to the community solely in digital form. As of July 2002, over 150 of the 233 survey fields are accessible on-line and the entire survey should be available early in 2003. A variety of scientific programmes for exploiting the survey are already underway and many more are anticipated now the digital survey data products are available.

  14. Research perspectives: The 2013 AAOS/ORS research symposium on Bone Quality and Fracture Prevention.

    PubMed

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

    2014-07-01

    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.

  15. Hot ortho-biologic topics at AAOS 2011†: platelet-rich plasma and related growth factors generate excitement.

    PubMed

    Hoggatt, Julie

    2011-06-01

    Several hot topics relating to ortho-biologics were discussed at the 2011 Annual Meeting of the American Academy of Orthopedic Surgery (AAOS) in San Diego this February. Injecting a patient's own platelet-rich plasma (PRP) prior to orthopedic surgery was an important topic, and had its own forum devoted to debating its uses and merit. PRP use has been promoted by equipment companies such as MTF Sports Medicine, Biomet, and Arteriocyte, but others are likely to take advantage of the trend of increasing PRP use by developing a proprietary injectable that mixes PRP with certain growth factors. One possible addition would be a recombinant platelet-derived growth factor (rhPDGF-BB, becaplermin) being developed by BioMimetic Therapeutics for its bone graft product. On the topic of viscosupplementation, the US's only single-injection product, Genzyme's SynviscOne®, was noticeably missing from the exhibit hall at AAOS, but an abstract comparing the single- and multiple-injection viscosupplementation techniques demonstrated that single-injection acts faster and is longer lasting. New bone morphogenetic protein formulations may improve healing of bone fractures. Molecular diagnostics may be used to predict periprosthetic joint infection, allowing orthopedic medicine to be more personalized. A diagnostic that can be used on a large scale has not yet been identified. † Adapted and reproduced from Hoggatt J. Hot Ortho-Biologic Topics at AAOS 2011: Platelet-Rich Plasma and Related Growth Factors Generate Excitement. inThought Research, 2011 Feb 28.

  16. The preparation of La2O3@AAO with simple hydrothermal method under ambient pressure and the enhanced electrowetting-on-dielectric performance

    NASA Astrophysics Data System (ADS)

    Jin, Hongxia; Wang, Jian; Yin, Yangyang; An, Yuying; Wang, Xiangzhuo; Li, Yan; Wang, Chengwei; Lv, Yudong

    2017-10-01

    Anodic aluminum oxide (AAO) has unique nanostructure and is a conventional EWOD material. The lanthanum oxide, a kind of rare-earth oxide, has unique electronic structure and high dielectric constant, but its synthesis is still complicated. A simple method is proposed to prepare the La2O3@AAO nanocomposites through immersing highly ordered AAO films into La(NO3)3 solution under ambient temperature and pressure and subsequent annealing. It can be known that when the immersion temperature gets to 60 °C, the La2O3 starts to grow in AAO by the characterization of morphology, crystal phase structure and surface chemical composition. The measurement of EWOD performance indicates that the incorporation of La2O3 into AAO greatly enhances the capacitance about 2-3 orders of magnitude, and the large contact angle modulation is acquired. Furthermore, the EW properties of La2O3@AAO nanocomposites, such as relaxation time, critical voltage, can be easily modulated by the immersion temperature and time.

  17. Easy-to-Fabricate and High-Sensitivity LSPR Type Specific Protein Detection Sensor Using AAO Nano-Pore Size Control.

    PubMed

    Kim, Sae-Wan; Lee, Jae-Sung; Lee, Sang-Won; Kang, Byoung-Ho; Kwon, Jin-Beom; Kim, Ok-Sik; Kim, Ju-Seong; Kim, Eung-Soo; Kwon, Dae-Hyuk; Kang, Shin-Won

    2017-04-13

    In this study, we developed a pore size/pore area-controlled optical biosensor-based anodic aluminum oxide (AAO) nanostructure. As the pore size of AAO increases, the unit cell of AAO increases, which also increases the non-pore area to which the antibody binds. The increase in the number of antibodies immobilized on the surface of the AAO enables effective detection of trace amounts of antigen, because increased antigen-antibody bonding results in a larger surface refractive index change. High sensitivity was thus achieved through amplification of the interference wave of two vertically-incident reflected waves through the localized surface plasmon resonance phenomenon. The sensitivity of the fabricated sensor was evaluated by measuring the change in wavelength with the change in the refractive index of the device surface, and sensitivity was increased with increasing pore-size and non-pore area. The sensitivity of the fabricated sensor was improved and up to 11.8 ag/mL serum amyloid A1 antigen was detected. In addition, the selectivity of the fabricated sensor was confirmed through a reaction with a heterogeneous substance, C-reactive protein antigen. By using hard anodization during fabrication of the AAO, the fabrication time of the device was reduced and the AAO chip was fabricated quickly and easily.

  18. Easy-to-Fabricate and High-Sensitivity LSPR Type Specific Protein Detection Sensor Using AAO Nano-Pore Size Control

    PubMed Central

    Kim, Sae-Wan; Lee, Jae-Sung; Lee, Sang-Won; Kang, Byoung-Ho; Kwon, Jin-Beom; Kim, Ok-Sik; Kim, Ju-Seong; Kim, Eung-Soo; Kwon, Dae-Hyuk; Kang, Shin-Won

    2017-01-01

    In this study, we developed a pore size/pore area-controlled optical biosensor-based anodic aluminum oxide (AAO) nanostructure. As the pore size of AAO increases, the unit cell of AAO increases, which also increases the non-pore area to which the antibody binds. The increase in the number of antibodies immobilized on the surface of the AAO enables effective detection of trace amounts of antigen, because increased antigen-antibody bonding results in a larger surface refractive index change. High sensitivity was thus achieved through amplification of the interference wave of two vertically-incident reflected waves through the localized surface plasmon resonance phenomenon. The sensitivity of the fabricated sensor was evaluated by measuring the change in wavelength with the change in the refractive index of the device surface, and sensitivity was increased with increasing pore-size and non-pore area. The sensitivity of the fabricated sensor was improved and up to 11.8 ag/mL serum amyloid A1 antigen was detected. In addition, the selectivity of the fabricated sensor was confirmed through a reaction with a heterogeneous substance, C-reactive protein antigen. By using hard anodization during fabrication of the AAO, the fabrication time of the device was reduced and the AAO chip was fabricated quickly and easily. PMID:28406469

  19. Tubular aggregates: their association with myalgia.

    PubMed Central

    Niakan, E; Harati, Y; Danon, M J

    1985-01-01

    Three thousand consecutive muscle biopsies were reviewed for the presence of tubular aggregates and their association with clinical symptomatology. Tubular aggregates were detected in 19 patients (0.6%). Twelve of these nineteen patients had severe myalgia, and the most abundant tubular aggregates were found in biopsies of patients with myalgia. Seven patients had only myalgia as their clinical symptomatology with normal physical examination. An additional five patients with tubular aggregates and myalgia had concomitant amyotrophic lateral sclerosis (2) or neuropathy (3). The high incidence of myalgia associated with tubular aggregates in our patients and the fact that tubular aggregates originate from sarcoplasmic reticulum suggest a role played by this structure in the pathogenesis of myalgia. Images PMID:2995591

  20. Renal tubular acidosis type 4 in pregnancy.

    PubMed

    Jakes, Adam Daniel; Baynes, Kevin; Nelson-Piercy, Catherine

    2016-03-17

    We describe the clinical course of renal tubular acidosis (RTA) type 4 in pregnancy, which has not been previously published. Renal tubular acidosis type 4 is a condition associated with increased urinary ammonia secondary to hypoaldosteronism or pseudohypoaldosteronism. Pregnancy may worsen the hyperkalaemia and acidosis of renal tubular acidosis type 4, possibly through an antialdosterone effect. We advise regular monitoring of potassium and pH throughout pregnancy to ensure safe levels are maintained.

  1. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. 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.

  3. Nano integrated lithium polymer electrolytes based on anodic aluminum oxide (AAO) templates

    NASA Astrophysics Data System (ADS)

    Bokalawela, Roshan S. P.

    Since their discovery in the 1970s, polymer electrolytes have been actively studied because they have properties important for many device applications. However, even after 40 years, the detailed mechanisms of conductivity in these electrolytes are still not completely understood. Moreover, the conductivity in polymer electrolytes is one of the limiting factors of these devices so that different methods to enhance conductivity are actively being explored. One proposed method of enhancing the conductivity is to confine the polymer electrolyte in the nanoscale, but the study of material properties at the nanoscale is challenging in this area. In this work, we confine poly(ethylene oxide) lithium triflate (PEO:LiTf)(X:1)X=10,30 polymer electrolytes in carefully fabricated nanometer-diameter anodized aluminum oxide (AAO) pore structures. We demonstrate two orders of magnitude higher conductivity in the confined structures versus that of bulk films. Using x-ray characterization we show that this increased conductivity is associated with ordered PEO polymer chains aligned in the template pore direction. The activation energy of the AAO-confined polymer electrolyte is found to be smaller than that of the unconfined melt and about half that of the unconfined solid. This result indicates that not only is the room-temperature confined polymer ordered, but that this order persists at temperatures where the nano-confined polymer electrolyte is expected to be a liquid. The geometric bulk resistances of the electrolytes were obtained by AC-impedance spectra, from which the ionic conductivities were calculated. The Arrhenius plots of temperature dependent ionic conductivities showed that the usual melting temperature of the PEO phase in confined PEO:LiTf(X:1) X=10,30 is suppressed and a single activation energy was evident throughout the temperature range 25--90 °C. Wide-angle x-ray scattering (WAXS) patterns show that the polymer chains in both the pure PEO and PEO:LiTf(10

  4. Multidimensional analysis of autonomous aerial observation systems (AAOS) for scientific, civil, and defense applications

    NASA Astrophysics Data System (ADS)

    Hutchinson, Mark A.; Hamill, Doris L.; Harrison, F. W.; Yetter, Jeffrey A.; Lawrence, Roland W.; Healy, Edward A.; Wright, Henry S.

    2004-12-01

    Better knowledge of the atmosphere, ocean and land are needed by a wide range of users spanning the scientific, civil and defense communities. Observations to provide this knowledge will require aerial systems with greater operational flexibility and lower life-cycle costs than are currently available. Persistent monitoring of severe storms, sampling and measurements of the Earth"s carbon cycle, wildfire monitoring/management, crop assessments, ozone and polar ice changes, and natural disaster response (communications and surveillance) are but a few applications where autonomous aerial observations can effectively augment existing measurement systems. User driven capabilities include high altitude, long range, long-loiter (days/weeks), smaller deployable sensor-ships for in-situ sampling, and sensors providing data with spectral bandwidth and high temporal and three-dimensional spatial resolution. Starting with user needs and considering all elements and activities required to acquire the needed observations leads to the definition of autonomous aerial observation systems (AAOS) that can significantly complement and extend the current Earth observation capability. In this approach, UAVs are viewed as only one, albeit important, element in a mission system and overall cost and performance for the user are the critical success factors. To better understand and meet the challenges of developing such AAOSs, a systems oriented multi-dimensional analysis has been performed that illuminates the enabling and high payoff investments that best address the needs of scientific, civil, and defense users of Earth observations. The analysis further identifies technology gaps and serves to illustrate how investments in a range of mission subsystems together can enable a new class of Earth observations.

  5. Hydrodynamic drive of tubular centrifuges

    SciTech Connect

    Tsybul'nik, A.P.

    1986-07-01

    A drive has been developed for a tubular centrifuge having a 10 kW ASTs-10-504 high-frequency electric motor with a synchronous rotation speed of 15,000 rpm. Despite a few demerits, the drive met the basic production requirements; simplicity and reliability of design, admissable rotation speed, and explosion resistance. However, this drive for tubular centrifuges had to be abandoned because experimental prototypes of high-frequency motors were used for the industrial tests and lot production of such motors is not probable in the near future. Industrial tests of a new hydrodynamic drive were performed, and the schematic diagram is shown. The hydrodrive was tested during centrifuge operation with polyester lac. It was found that the hydodynamic drive is distinguished by operational reliability and easy serviceability, holds promise for increased centrifuge speed, ensures smooth start of the centrifuge and satisfactory stability of the rotor rotation speed in the steady regime, reliably protects the motor from overloading and is fully explosion-proof.

  6. Design of hybrid composite tubulars

    SciTech Connect

    Ochoa, O.O.; Ross, G.R.; Liggett, G.M.

    1996-12-01

    Hybrid composite tubulars are one of the unique structures that illustrate the tailorability of composites to offshore operating conditions. Herein, the focus is on filament wound composite tubulars that have glass and carbon as reinforcing fibers within the same thermoset matrix. In the present research program, the multiple scales associated with the material constituents and the geometric configuration are analytically and experimentally examined. The first scale is at the micromechanics level where the interaction between the two different fiber types and the matrix are studied in terms of moisture absorption and potential debonds. Experiments are conducted on sea water saturated coupons to capture the aging effect on the material properties. The second scale is at the structural level and focuses on the optimization of the filament wound hybrid composite tube geometry. The global tube response efforts focus on the recommended stacking sequence as well as the degree of hybridization to carry combined axial and pressure loads. ABAQUS{copyright} is used to model the tube subjected to moisture and thermomechanical loads with composite shell elements. The mechanical loads considered are axial tension and internal pressure. The results to date indicate that the implementation of a progressive failure criteria in the finite element procedure accurately captures the response observed in testing of pressurized composite tubes. Structural similitude is used to relate the behavior of model tubes to candidate prototypes capable of withstanding the dynamic loads associated with currents and waves.

  7. Inconsistencies Between Physician-Reported Disclosures at the AAOS Annual Meeting and Industry-Reported Financial Disclosures in the Open Payments Database.

    PubMed

    Hannon, Charles P; Chalmers, Peter N; Carpiniello, Matthew F; Cvetanovich, Gregory L; Cole, Brian J; Bach, Bernard R

    2016-10-19

    The purpose of this study was to determine the rate and type of inconsistencies between disclosures self-reported by physicians at a major academic meeting in the United States and industry-reported disclosures in the Open Payments database for a concordant time period. Disclosures for every first and last author from the United States with a medical degree of a podium or poster presentation at the 2014 American Academy of Orthopaedic Surgeons (AAOS) Annual Meeting were collected and were compared with the disclosures reported in the Open Payments database to determine if any inconsistencies were present and, if so, within which category. In total, 1,925 total AAOS presenters were identified, and 1,113 met the inclusion criteria. Based on AAOS disclosures, 432 (39%) should have been listed within the Open Payments database. There were 125 presenters (11%) who reported an AAOS disclosure and thus should have been included in the Open Payments database, but were not included. An additional 259 presenters (23%) had ≥1 AAOS disclosures that were not reported or were improperly categorized in the Open Payments database. Inconsistencies were more common for authors who had significantly more poster presentations (p < 0.001), podium presentations (p = 0.01), total presentations (p < 0.001), and AAOS disclosures (p < 0.001) and a significantly higher value of payments in the Open Payments database (p < 0.001). In this sample, there was a 35% rate of inconsistency between physician-reported financial relationships for presenters at the AAOS Annual Meeting and industry-reported relationships published in the Open Payments database. Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.

  8. 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

  9. The effect of acyclovir on the tubular secretion of creatinine in vitro

    PubMed Central

    2010-01-01

    Background While generally well tolerated, severe nephrotoxicity has been observed in some children receiving acyclovir. A pronounced elevation in plasma creatinine in the absence of other clinical manifestations of overt nephrotoxicity has been frequently documented. Several drugs have been shown to increase plasma creatinine by inhibiting its renal tubular secretion rather than by decreasing glomerular filtration rate (GFR). Creatinine and acyclovir may be transported by similar tubular transport mechanisms, thus, it is plausible that in some cases, the observed increase in plasma creatinine may be partially due to inhibition of tubular secretion of creatinine, and not solely due to decreased GFR. Our objective was to determine whether acyclovir inhibits the tubular secretion of creatinine. Methods Porcine (LLC-PK1) and human (HK-2) renal proximal tubular cell monolayers cultured on microporous membrane filters were exposed to [2-14C] creatinine (5 μM) in the absence or presence of quinidine (1E+03 μM), cimetidine (1E+03 μM) or acyclovir (22 - 89 μM) in incubation medium. Results Results illustrated that in evident contrast to quinidine, acyclovir did not inhibit creatinine transport in LLC-PK1 and HK-2 cell monolayers. Conclusions The results suggest that acyclovir does not affect the renal tubular handling of creatinine, and hence, the pronounced, transient increase in plasma creatinine is due to decreased GFR, and not to a spurious increase in plasma creatinine. PMID:21192814

  10. Matrigel-induced tubular morphogenesis of human eccrine sweat gland epithelial cells.

    PubMed

    Lei, Xia; Liu, Bo; Wu, Jinjin; Lu, Yuangang; Yang, Yadong

    2011-09-01

    Human eccrine sweat glands are tubule-structured glands of the skin that are vital in thermoregulation, secretion, and excretion of water and electrolytes. A study of tubular morphogenesis in vitro would facilitate the development of a tissue engineering model for eccrine sweat glands and other tubule-structured glands. Matrigel, a basement membrane matrix, has been shown to promote differentiation and morphogenesis of many different cell types, including tubular cells. This study investigated the growth, differentiation, and tubular morphogenesis of human eccrine sweat gland epithelial cells cultured in Matrigel. Human eccrine gland epithelial cells were isolated and cultured in vitro. The cell growth in Matrigel was evidenced by the formation of cell clusters, which were observed under an inverted microscope. The internal structure of the cell clusters was further investigated by hematoxylin-eosin (HE) staining and confocal laser scanning microscopy (CLSM) of propidium iodide-stained nuclei. The results demonstrated that although on a plastic surface or in a collagen gel the cells could not form tubular structures, they formed tubular structures when cultured in Matrigel. Consequently, we conclude that Matrigel can promote tubular morphogenesis of human eccrine sweat gland epithelial cells.

  11. 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.

  12. 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.

  13. Drp1 dephosphorylation in ATP depletion-induced mitochondrial injury and tubular cell apoptosis.

    PubMed

    Cho, Sung-Gyu; Du, Quansheng; Huang, Shuang; Dong, Zheng

    2010-07-01

    Recent studies revealed a striking morphological change of mitochondria during apoptosis. Mitochondria become fragmented and notably, the fragmentation contributes to mitochondrial outer membrane permeabilization and consequent release of apoptotic factors. In renal tubular cells, mitochondrial fragmentation involves the activation of Drp1, a key mitochondrial fission protein. However, it is unclear how Drp1 is regulated during tubular cell apoptosis. In this study, we examined Drp1 regulation during tubular cell apoptosis following ATP depletion. Rat kidney proximal tubular cells (RPTC) were subjected to azide treatment or severe hypoxia in glucose-free medium to induce ATP depletion. During ATP depletion, Drp1 was shown to be dephosphorylated at serine-637. Drp1 dephosphorylation could be suppressed by cyclosporine A and FK506, two calcineurin inhibitors. Importantly, cyclosporine A and FK506 could also prevent mitochondrial fragmentation, Bax accumulation, cytochrome c release, and apoptosis following ATP depletion in RPTC. The results suggest that calcineurin-mediated serine-637 dephosphorylation is involved in Drp1 activation during ATP depletion in renal tubular cells. Upon activation, Drp1 contributes to mitochondrial fragmentation and outer membrane permeabilization, resulting in the release of apoptogenic factors and apoptosis.

  14. A case of distal renal tubular acidosis, Southeast Asian ovalocytosis and possible fluorosis.

    PubMed

    Vithanage, J P; Ekanayake, M

    2009-03-01

    A 39-year old man had periodic paralysis due to hypokalaemia. Investigations led to the diagnosis of distal renal tubular acidosis (dRTA) and Southeast Asian ovalocytosis (SAO). Both can originate in mutations of the anion-exchanger 1 gene (AE1), which codes for band 3, the bicarbonate/chloride exchanger in both the red cell membrane and the basolateral membrane of the collecting tubule alpha-intercalated cell. The finding of diffuse osteosclerosis led to the suspicion of coexisting fluorosis.

  15. 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.

  16. Progress in Nano-Engineered Anodic Aluminum Oxide Membrane Development

    PubMed Central

    Poinern, Gerrard Eddy Jai; Ali, Nurshahidah; Fawcett, Derek

    2011-01-01

    The anodization of aluminum is an electro-chemical process that changes the surface chemistry of the metal, via oxidation, to produce an anodic oxide layer. During this process a self organized, highly ordered array of cylindrical shaped pores can be produced with controllable pore diameters, periodicity and density distribution. This enables anodic aluminum oxide (AAO) membranes to be used as templates in a variety of nanotechnology applications without the need for expensive lithographical techniques. This review article is an overview of the current state of research on AAO membranes and the various applications of nanotechnology that use them in the manufacture of nano-materials and devices or incorporate them into specific applications such as biological/chemical sensors, nano-electronic devices, filter membranes and medical scaffolds for tissue engineering. PMID:28880002

  17. 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.

  18. 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.

  19. 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

  20. Hyperammonaemia with distal renal tubular acidosis.

    PubMed

    Miller, S G; Schwartz, G J

    1997-11-01

    The case is reported of an infant with hyperammonaemia secondary to severe distal renal tubular acidosis. A clinical association between increased concentrations of ammonia in serum and renal tubular acidosis has not previously been described. In response to acidosis the infant's kidneys presumably increased ammonia synthesis but did not excrete ammonia, resulting in hyperammonaemia. The patient showed poor feeding, frequent vomiting, and failure to thrive, but did not have an inborn error of metabolism. This case report should alert doctors to consider renal tubular acidosis in the differential diagnosis of severely ill infants with metabolic acidosis and hyperammonaemia.

  1. 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

  2. Formation and Stability of Lipid Membrane Nanotubes.

    PubMed

    Bahrami, Amir Houshang; Hummer, Gerhard

    2017-09-26

    Lipid membrane nanotubes are abundant in living cells, even though tubules are energetically less stable than sheet-like structures. According to membrane elastic theory, the tubular endoplasmic reticulum (ER), with its high area-to-volume ratio, appears to be particularly unstable. We explore how tubular membrane structures can nevertheless be induced and why they persist. In Monte Carlo simulations of a fluid-elastic membrane model subject to thermal fluctuations and without constraints on symmetry, we find that a steady increase in the area-to-volume ratio readily induces tubular structures. In simulations mimicking the ER wrapped around the cell nucleus, tubules emerge naturally as the membrane area increases. Once formed, a high energy barrier separates tubules from the thermodynamically favored sheet-like membrane structures. Remarkably, this barrier persists even at large area-to-volume ratios, protecting tubules against shape transformations despite enormous driving forces toward sheet-like structures. Molecular dynamics simulations of a molecular membrane model confirm the metastability of tubular structures. Volume reduction by osmotic regulation and membrane area growth by lipid production and by fusion of small vesicles emerge as powerful factors in the induction and stabilization of tubular membrane structures.

  3. Tubular discharge in a magnetic field

    SciTech Connect

    Karasev, V.Yu.; Semenov, R.I.; Chaika, M.P.

    1995-04-01

    Visual observations of Xe discharge glow in an axial magnetic field are described. Tubular discharge is detected in a narrow range of the parameters p, I, and H. A qualitative explanation of this effect is proposed.

  4. 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.

  5. 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.

  6. Genetics Home Reference: tubular aggregate myopathy

    MedlinePlus

    ... in both type I and type II fibers, forming clumps of tube-like structures called tubular aggregates. ... Hyun C, Woo JS, Park CS, Kim do H, Lee EH. Stromal interaction molecule 1 (STIM1) regulates ...

  7. 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

  8. 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. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

  9. Protein-Mediated Transformation of Lipid Vesicles into Tubular Networks

    PubMed Central

    Simunovic, Mijo; Mim, Carsten; Marlovits, Thomas C.; Resch, Guenter; Unger, Vinzenz M.; Voth, Gregory A.

    2013-01-01

    Key cellular processes are frequently accompanied by protein-facilitated shape changes in the plasma membrane. N-BAR-domain protein modules generate curvature by means of complex interactions with the membrane surface. The way they assemble and the mechanism by which they operate are largely dependent on their binding density. Although the mechanism at lower densities has recently begun to emerge, how membrane scaffolds form at high densities remains unclear. By combining electron microscopy and multiscale simulations, we show that N-BAR proteins at high densities can transform a lipid vesicle into a 3D tubular network. We show that this process is a consequence of excess adhesive energy combined with the local stiffening of the membrane, which occurs in a narrow range of mechanical properties of both the membrane and the protein. We show that lipid diffusion is significantly reduced by protein binding at this density regime and even more in areas of high Gaussian curvature, indicating a potential effect on molecular transport in cells. Finally, we reveal that the breaking of the bilayer topology is accompanied by the nematic arrangement of the protein on the surface, a structural motif that likely drives the formation of reticular structures in living cells. PMID:23931319

  10. Apical targeting of the formin Diaphanous in Drosophila tubular epithelia

    PubMed Central

    Rousso, Tal; Shewan, Annette M; Mostov, Keith E; Schejter, Eyal D; Shilo, Ben-Zion

    2013-01-01

    Apical secretion from epithelial tubes of the Drosophila embryo is mediated by apical F-actin cables generated by the formin-family protein Diaphanous (Dia). Apical localization and activity of Dia are at the core of restricting F-actin formation to the correct membrane domain. Here we identify the mechanisms that target Dia to the apical surface. PI(4,5)P2 levels at the apical membrane regulate Dia localization in both the MDCK cyst model and in Drosophila tubular epithelia. An N-terminal basic domain of Dia is crucial for apical localization, implying direct binding to PI(4,5)P2. Dia apical targeting also depends on binding to Rho1, which is critical for activation-induced conformational change, as well as physically anchoring Dia to the apical membrane. We demonstrate that binding to Rho1 facilitates interaction with PI(4,5)P2 at the plane of the membrane. Together these cues ensure efficient and distinct restriction of Dia to the apical membrane. DOI: http://dx.doi.org/10.7554/eLife.00666.001 PMID:23853710

  11. 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.

  12. 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...

  13. 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

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

    PubMed

    Maggiorani, Damien; Dissard, Romain; 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 48 h. 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.

  15. Response of human renal tubular cells to cyclosporine and sirolimus: a toxicogenomic study.

    PubMed

    Pallet, Nicolas; Rabant, Marion; Xu-Dubois, Yi-Chun; Lecorre, Delphine; Mucchielli, Marie-Hélène; Imbeaud, Sandrine; Agier, Nicolas; Hertig, Alexandre; Thervet, Eric; Legendre, Christophe; Beaune, Philippe; Anglicheau, Dany

    2008-06-01

    The molecular mechanisms involved in the potentially nephrotoxic response of tubular cells to immunosuppressive drugs remain poorly understood. Transcriptional profiles of human proximal tubular cells exposed to cyclosporine A (CsA), sirolimus (SRL) or their combination, were established using oligonucleotide microarrays. Hierarchical clustering of genes implicated in fibrotic processes showed a clear distinction between expression profiles with CsA and CsA+SRL treatments on the one hand and SRL treatment on the other. Functional analysis found that CsA and CsA+SRL treatments preferentially alter biological processes located at the cell membrane, such as ion transport or signal transduction, whereas SRL modifies biological processes within the nucleus and related to transcriptional activity. Genome wide expression analysis suggested that CsA may induce an endoplasmic reticulum (ER) stress in tubular cells in vitro. Moreover we found that CsA exposure in vivo is associated with the upregulation of the ER stress marker BIP in kidney transplant biopsies. In conclusion, this toxicogenomic study highlights the molecular interaction networks that may contribute to the tubular response to CsA and SRL. These results may also offer a new working hypothesis for future research in the field of CsA nephrotoxicity. Further studies are needed to evaluate if ER stress detection in tubular cells in human biopsies can predict CsA nephrotoxicity.

  16. Response of human renal tubular cells to cyclosporine and sirolimus: A toxicogenomic study

    SciTech Connect

    Pallet, Nicolas Rabant, Marion; Xu-Dubois, Yi-Chun; LeCorre, Delphine; Mucchielli, Marie-Helene; Imbeaud, Sandrine; Agier, Nicolas; Thervet, Eric; Legendre, Christophe; Beaune, Philippe; Anglicheau, Dany

    2008-06-01

    The molecular mechanisms involved in the potentially nephrotoxic response of tubular cells to immunosuppressive drugs remain poorly understood. Transcriptional profiles of human proximal tubular cells exposed to cyclosporine A (CsA), sirolimus (SRL) or their combination, were established using oligonucleotide microarrays. Hierarchical clustering of genes implicated in fibrotic processes showed a clear distinction between expression profiles with CsA and CsA + SRL treatments on the one hand and SRL treatment on the other. Functional analysis found that CsA and CsA + SRL treatments preferentially alter biological processes located at the cell membrane, such as ion transport or signal transduction, whereas SRL modifies biological processes within the nucleus and related to transcriptional activity. Genome wide expression analysis suggested that CsA may induce an endoplasmic reticulum (ER) stress in tubular cells in vitro. Moreover we found that CsA exposure in vivo is associated with the upregulation of the ER stress marker BIP in kidney transplant biopsies. In conclusion, this toxicogenomic study highlights the molecular interaction networks that may contribute to the tubular response to CsA and SRL. These results may also offer a new working hypothesis for future research in the field of CsA nephrotoxicity. Further studies are needed to evaluate if ER stress detection in tubular cells in human biopsies can predict CsA nephrotoxicity.

  17. An integrative overview on the mechanisms underlying the renal tubular cytotoxicity of gentamicin.

    PubMed

    Quiros, Yaremi; Vicente-Vicente, Laura; Morales, Ana I; López-Novoa, José M; López-Hernández, Francisco J

    2011-02-01

    Gentamicin is an aminoglycoside antibiotic widely used against infections by Gram-negative microorganisms. Nephrotoxicity is the main limitation to its therapeutic efficacy. Gentamicin nephrotoxicity occurs in 10-20% of therapeutic regimes. A central aspect of gentamicin nephrotoxicity is its tubular effect, which may range from a mere loss of the brush border in epithelial cells to an overt tubular necrosis. Tubular cytotoxicity is the consequence of many interconnected actions, triggered by drug accumulation in epithelial tubular cells. Accumulation results from the presence of the endocytic receptor complex formed by megalin and cubulin, which transports proteins and organic cations inside the cells. Gentamicin then accesses and accumulates in the endosomal compartment, the Golgi and endoplasmic reticulum (ER), causes ER stress, and unleashes the unfolded protein response. An excessive concentration of the drug over an undetermined threshold destabilizes intracellular membranes and the drug redistributes through the cytosol. It then acts on mitochondria to unleash the intrinsic pathway of apoptosis. In addition, lysosomal cathepsins lose confinement and, depending on their new cytosolic concentration, they contribute to the activation of apoptosis or produce a massive proteolysis. However, other effects of gentamicin have also been linked to cell death, such as phospholipidosis, oxidative stress, extracellular calcium-sensing receptor stimulation, and energetic catastrophe. Besides, indirect effects of gentamicin, such as reduced renal blood flow and inflammation, may also contribute or amplify its cytotoxicity. The purpose of this review was to critically integrate all these effects and discuss their relative contribution to tubular cell death.

  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. 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

  20. Buckling and lockup of tubulars in inclined wellbores

    SciTech Connect

    Wu, J.; Juvkam-Wold, H.C.

    1994-12-31

    This paper describes sinusoidal and helical buckling of tubulars in inclined wellbores and the ``lockup`` of tubulars due to buckling. The results show that tubular buckling starts from the tubular bottom in low-inclination wellbores, where axial compressive load is largest due to tubular weight. In high inclination wellbores it may start from the top portion of the tubular, where axial compressive load is largest due to frictional drag. This clarifies the confusion about whether or not tubulars buckle all at once, in the entire inclined wellbore. New sinusoidal and helical buckling load equations are presented to give better tubular buckling prediction in inclined wellbores (0--90 degrees). They show that the lower the wellbore inclination angle, the smaller the axial compressive load to initiate tubular buckling. But a certain non-zero axial compressive load is still needed to buckle the tubulars in vertical wellbores. When tubulars buckle helically, a large wall contact force will be generated. The `slack-off` weight at the surface will not be fully transmitted to the bottom of the tubulars due to the large resultant frictional drag. The ``lockup`` of tubulars, where the bottom load (bit weight) cannot be increased by slacking-off weight at the surface, usually is approached when a large portion of the tubular buckles helically in the wellbore.

  1. Buckling and lockup of tubulars in inclined wellbores

    SciTech Connect

    Wu, J.; Juvkam-Wold, H.C.

    1995-09-01

    This paper studies sinusoidal and helical buckling of tubulars in inclined wellbores and the ``lockup`` of tubulars due to buckling. The results show that tubular buckling starts from the tubular bottom in low-inclination wellbores, where the axial compressive load is largest due to tubular weight. In high-inclination wellbores it may start from the top portion of the tubular, where the axial compressive load is largest due to frictional drag. This clarifies the confusion on whether or not the tubular buckles at once on it entire length in inclined wellbores. New sinusoidal and helical buckling load equations are presented to better predict tubular buckling in inclined wellbores (0--90 deg). The lower the wellbore inclination angle, the smaller the axial compressive load required to initiate tubular buckling. However, a certain nonzero axial compressive load is still needed to buckle the tubulars in vertical wellbores. When tubulars buckle helically, a large wall contact force will be generated, and the ``slack-off`` weight at the surface will not be fully transmitted to the tubular bottom due to large resultant frictional drag. The ``lockup`` of tubulars may even occur, where the tubular bottom load cannot be increased by slacking-off weight at the surface.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. The effect of wellbore curvature on tubular buckling and lockup

    SciTech Connect

    Wu, J.; Juvkam-Wold, H.C.

    1995-09-01

    This paper studies tubular buckling in curved wellbores (such as the build section of horizontal wells) and its effect on tubular ``lockup`` in horizontal or extended-reach wells. New buckling load equations are derived to properly predict tubular sinusoidal and helical buckling in such wellbores. The results show that the buckling loads to initiate sinusoidal and helical buckling to tubulars in curved wellbores are usually much larger than those in straight wellbores. This is because the curved wellbore tends to hold the axially compressed tubular against the outer-curve side of the wellbore. The tubular becomes less easy to buckle until higher axial compressive loads are applied. Less tubular lockup risk is then predicted for tubulars in horizontal or extended-reach wells by using the new buckling load equations. The new buckling loads in curved wellbores agree with those in straight wellbores when wellbore curvature approaches zero. Small-scale laboratory experiments also confirmed these theoretically derived buckling loads.

  8. Fabrication of Mesoporous Silica/Alumina Hybrid Membrane Film Nanocomposites using Template Sol-Gel Synthesis of Amphiphilic Triphenylene

    NASA Astrophysics Data System (ADS)

    Lintang, H. O.; Jalani, M. A.; Yuliati, L.; Salleh, M. M.

    2017-05-01

    Herein we reported that by introducing a one-dimensional (1D) substrate with a porous structure such as anodic aluminum oxide (AAO) membrane, mesoporous silica/alumina hybrid nanocomposites were successfully fabricated by using amphiphilic triphenylene (TPC10TEG) as a template in sol-gel synthesis (TPC10TEG/silicahex). For the optical study of the nanocomposites, TPC10TEG/silicahex showed absorption peak at 264 nm due to the ordered and long-range π-π stacking of the disc-like aromatic triphenylene core. Moreover, the hexagonal arrangement of TPC10TEG/silicahex was proven based on their diffraction peaks of d 100 and d 200 at 2θ = 2.52° and 5.04° and images of transmission electron microscopy (TEM), respectively. For fabrication of mesoporous silica/alumina hybrid membrane, TPC10TEG/silicahex was drop-casted onto AAO membrane for penetration into the porous structure via gravity. X-ray diffraction (XRD) analysis on the resulted hybrid nanocomposites showed that the diffraction peaks of d 100 and d 200 of TPC10TEG/silicahex were still preserved, indicating that the hexagonal arrangements of mesoporous silica were maintained even on AAO substrate. The morphology study on the hybrid nanocomposites using TEM, scanning electron microscope (SEM) and field emission scanning electron microscope (FE-SEM) showed the successful filling of most AAO channels with the TPC10TEG/silicahex nanocomposites.

  9. Observational analysis of BOA free-papers (2001): from presentation to publication and comparison with the American Academy of Orthopaedic Surgeons (AAOS).

    PubMed

    ul Haq, Muhammad Imran; Gill, Inder

    2011-04-01

    The objectives of this study were to: determine the presentation to publication conversion rate (PPCR) in peer-reviewed indexed journals of free papers and posters presented at 12-14th September 2001 British Orthopaedic Association (BOA) annual meeting and to compare the publication rate with the American Academy of Orthopaedic Surgeons (AAOS) meeting in 2001. We looked at all presentations including both podium and poster presentations at British Orthopaedic Association meeting held in 2001 and assessed for subsequent publication as full-text article with a fixed PubMed search protocol. Once the abstract was identified as being published, we noted the name of the journal, citation, and time to presentation. The level of evidence was assigned for each abstract along the guidelines published by the centre for evidence-based medicine, Oxford, UK. This conversion rate was compared with the presentation to publication rate for the AAOS meeting in 2001. A total of 179 abstracts were presented at the 2001 BOA meeting. 65 of these were published as full-text articles in 30 different journals. The overall publication rate was 36.3%. The publication rate of the papers presented at AAOS annual meeting 2001 was 49% (367/756). The mean time from presentation to publication was 18.6 months (±9.4 months). Three fourths of them were published after 2 years of presentations (63% for AAOS). Majority of studies were either level III or IV. 14 full-text articles were published in Journal of Bone and Joint Surgery British (JBJS Br) and 8 in the Injury Journal. This is the first study reporting the publication rate of presentations for BOA meeting and comparing it with the publication rate of AAOS meeting in 2001. The publication rate of BOA presentations is much lower than the AAOS meeting. We believe the publication rate is an important tool in judging the quality of research work and the reputation of a scientific meeting with higher conversion rates suggesting better quality. Thus

  10. Quantitative proteomics reveal proteins enriched in tubular endoplasmic reticulum of Saccharomyces cerevisiae

    PubMed Central

    Wang, Xinbo; Li, Shanshan; Wang, Haicheng; Shui, Wenqing; Hu, Junjie

    2017-01-01

    The tubular network is a critical part of the endoplasmic reticulum (ER). The network is shaped by the reticulons and REEPs/Yop1p that generate tubules by inducing high membrane curvature, and the dynamin-like GTPases atlastin and Sey1p/RHD3 that connect tubules via membrane fusion. However, the specific functions of this ER domain are not clear. Here, we isolated tubule-based microsomes from Saccharomyces cerevisiae via classical cell fractionation and detergent-free immunoprecipitation of Flag-tagged Yop1p, which specifically localizes to ER tubules. In quantitative comparisons of tubule-derived and total microsomes, we identified a total of 79 proteins that were enriched in the ER tubules, including known proteins that organize the tubular ER network. Functional categorization of the list of proteins revealed that the tubular ER network may be involved in membrane trafficking, lipid metabolism, organelle contact, and stress sensing. We propose that affinity isolation coupled with quantitative proteomics is a useful tool for investigating ER functions. DOI: http://dx.doi.org/10.7554/eLife.23816.001 PMID:28287394

  11. 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

  12. 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.

  13. Boron--epoxy tubular structure members

    NASA Technical Reports Server (NTRS)

    Shakespeare, W. B. J.; Nelson, P. T.; Lindkvist, E. C.

    1973-01-01

    Composite materials fabricate thin-walled tubular members which have same load-carrying capabilities as aluminum, titanium, or other metals, but are lighter. Interface between stepped end fitting and tube lends itself to attachments by primary as well as secondary bonding. Interlaminar shear and hoop stress buildup in attachment at end fitting is avoided.

  14. Drill pipes and casings utilizing multi-conduit tubulars

    SciTech Connect

    Curlett, H.B.

    1989-01-24

    A seal adapted for use with a multi-conduit well tubular, or the like, is described which consists of: a plate with fluid passages, each passage corresponding to an opening of a conduit of the multiconduit tubular, and a groove on the plate around each passage; and elastomer means partially embeddable into each groove for sealing each conduit of a tubular to a corresponding conduit of another similar tubular.

  15. Coating mechanism of polybenzoxazine onto tubular alumina support for ethanol-water separation

    NASA Astrophysics Data System (ADS)

    Wongkasemjit, Sujitra; Chuntanalerg, Panupong; Saelim, Ni-On; Kulthippanja, Santi; Chaisuwan, Thanyalak

    2014-03-01

    Tubular α-Al2O3 supported polybenzoxazine (PBZ) membranes were prepared by dip-coating technique for ethanol-water separation via pervaporation. The effect of PBZ concentration on number of dipping cycle requirement and separation performance was studied. Based on the obtained results, a possible mechanism of the membrane formation was investigated and proposed. It was founded that two membrane preparation steps were involved, viz. transition layer accumulation and layer formation. The membrane prepared by using 25 wt% PBZ needed the shortest preparation time and provided the highest separation factor. Moreover, the prepared membrane had excellent stability in every feed ethanol concentration with the separation factor higher than 10,000. The study of a long-term pervaporation in 90:10 ethanol:water feed was also carried out and the results showed the excellent durability during 11 days of operation with 99.45 wt% of ethanol..

  16. A Theoretical Analysis of the Capacitance of Muscle Fibers Using a Distributed Model of the Tubular System

    PubMed Central

    Eisenberg, R. S.; Vaughan, P. C.; Howell, J. N.

    1972-01-01

    A model is developed to predict the changes in total capacitance (i.e. total charge stored divided by surface membrane potential) of the tubular system of muscle fibers. The tubular system is represented as a punctated disc and the area of membrane across which current flows is represented as a punctated annulus, the capacitance of the muscle fiber being proportional to this area. The area can be determined from a distributed model of the tubular system, in which the only resistance to radial current flow is presumed to be in the lumen of the tubules. Calculations are made of the variation of capacitance expected as the conductivity of the bathing solution is varied. These calculations include the effects of fixed charge in the tubular lumen and the effects of changes in the shape and volume of the tubular system in solutions of low conductivity. The calculated results fail to fit comparable experimental data, although they do qualitatively account for the known variation of the radial spread of contraction with conductivity of the bathing medium. It is pointed out that the existence of a significant "access resistance" at the mouth of the tubules might explain the discrepancy between theory and experiment. PMID:5058964

  17. TRAP1 ameliorates renal tubulointerstitial fibrosis in mice with unilateral ureteral obstruction by protecting renal tubular epithelial cell mitochondria.

    PubMed

    Chen, Jun-Feng; Wu, Qi-Shun; Xie, Yu-Xian; Si, Bo-Lin; Yang, Ping-Ping; Wang, Wen-Yan; Hua, Qin; He, Qing

    2017-10-01

    Mitochondrial dysfunction causes renal tubular epithelial cell injury and promotes cell apoptosis and renal tubulointerstitial fibrosis (TIF) progression. TNF receptor-associated protein 1 (TRAP1) is a molecular chaperone protein that is localized in mitochondria. It plays an important role in cell apoptosis; however, its functional mechanism in TIF remains unclear. In this study, we observed the effects of TRAP1 in renal tubular epithelial cell mitochondria in mice with unilateral ureteral obstruction and its function in cell apoptosis and TIF. Results show that TRAP1 could protect the mitochondrial structure in renal tubular epithelial cells; maintain the levels of mitochondrial membrane potential, ATP, and mitochondrial DNA copy number; inhibit reactive oxygen species production; stabilize the expression of the mitochondrial inner membrane protein mitofilin; reduce renal tubular epithelial cell apoptosis; and inhibit TIF. These results provide new theoretical foundations for additional understanding of the antifibrotic mechanism of TRAP1 in the kidney.-Chen, J.-F., Wu, Q.-S., Xie, Y.-X., Si, B.-L., Yang, P.-P., Wang, W.-Y., Hua, Q., He, Q. TRAP1 ameliorates renal tubulointerstitial fibrosis in mice with unilateral ureteral obstruction by protecting renal tubular epithelial cell mitochondria. © FASEB.

  18. Molecular weight dependence of the intrinsic size effect on Tg in AAO template-supported polymer nanorods: A DSC study

    NASA Astrophysics Data System (ADS)

    Askar, Shadid; Wei, Tong; Tan, Anthony W.; Torkelson, John M.

    2017-05-01

    Many studies have established a major effect of nanoscale confinement on the glass transition temperature (Tg) of polystyrene (PS), most commonly in thin films with one or two free surfaces. Here, we characterize smaller yet significant intrinsic size effects (in the absence of free surfaces or significant attractive polymer-substrate interactions) on the Tg and fragility of PS. Melt infiltration of various molecular weights (MWs) of PS into anodic aluminum oxide (AAO) templates is used to create nanorods supported on AAO with rod diameter (d) ranging from 24 to 210 nm. The Tg (both as Tg,onset and fictive temperature) and fragility values are characterized by differential scanning calorimetry. No intrinsic size effect is observed for 30 kg/mol PS in template-supported nanorods with d = 24 nm. However, effects on Tg are present for PS nanorods with Mn and Mw ≥ ˜175 kg/mol, with effects increasing in magnitude with increasing MW. For example, in 24-nm-diameter template-supported nanorods, Tg, rod - Tg, bulk = -2.0 to -2.5 °C for PS with Mn = 175 kg/mol and Mw = 182 kg/mol, and Tg, rod - Tg, bulk = ˜-8 °C for PS with Mn = 929 kg/mol and Mw = 1420 kg/mol. In general, reductions in Tg occur when d ≤ ˜2Rg, where Rg is the bulk polymer radius of gyration. Thus, intrinsic size effects are significant when the rod diameter is smaller than the diameter (2Rg) associated with the spherical volume pervaded by coils in bulk. We hypothesize that the Tg reduction occurs when chain segment packing frustration is sufficiently perturbed by confinement in the nanorods. This explanation is supported by observed reductions in fragility with the increasing extent of confinement. We also explain why these small intrinsic size effects do not contradict reports that the Tg-confinement effect in supported PS films with one free surface exhibits little or no MW dependence.

  19. Molecular weight dependence of the intrinsic size effect on Tg in AAO template-supported polymer nanorods: A DSC study.

    PubMed

    Askar, Shadid; Wei, Tong; Tan, Anthony W; Torkelson, John M

    2017-05-28

    Many studies have established a major effect of nanoscale confinement on the glass transition temperature (Tg) of polystyrene (PS), most commonly in thin films with one or two free surfaces. Here, we characterize smaller yet significant intrinsic size effects (in the absence of free surfaces or significant attractive polymer-substrate interactions) on the Tg and fragility of PS. Melt infiltration of various molecular weights (MWs) of PS into anodic aluminum oxide (AAO) templates is used to create nanorods supported on AAO with rod diameter (d) ranging from 24 to 210 nm. The Tg (both as Tg,onset and fictive temperature) and fragility values are characterized by differential scanning calorimetry. No intrinsic size effect is observed for 30 kg/mol PS in template-supported nanorods with d = 24 nm. However, effects on Tg are present for PS nanorods with Mn and Mw ≥ ∼175 kg/mol, with effects increasing in magnitude with increasing MW. For example, in 24-nm-diameter template-supported nanorods, Tg, rod - Tg, bulk = -2.0 to -2.5 °C for PS with Mn = 175 kg/mol and Mw = 182 kg/mol, and Tg, rod - Tg, bulk = ∼-8 °C for PS with Mn = 929 kg/mol and Mw = 1420 kg/mol. In general, reductions in Tg occur when d ≤ ∼2Rg, where Rg is the bulk polymer radius of gyration. Thus, intrinsic size effects are significant when the rod diameter is smaller than the diameter (2Rg) associated with the spherical volume pervaded by coils in bulk. We hypothesize that the Tg reduction occurs when chain segment packing frustration is sufficiently perturbed by confinement in the nanorods. This explanation is supported by observed reductions in fragility with the increasing extent of confinement. We also explain why these small intrinsic size effects do not contradict reports that the Tg-confinement effect in supported PS films with one free surface exhibits little or no MW dependence.

  20. Surgical Treatment of Tubular Breast Type II

    PubMed Central

    Dabizha, Oleksii Y.; Kostenko, Alona A.; Gomolyako, Irina V.; Samko, Kristina A.; Borovyk, Denys V.

    2016-01-01

    Background: Tubular breasts are caused by connective tissue malformation and occur in puberty. The main clinical characteristics of the tubular breast are breast asymmetry, dense fibrous ring around the areola, hernia bulging of the areola, megaareola, and hypoplasia of quadrants of the breast. Pathology causes great psychological discomfort to patients. Methods: This study included 17 patients, aged 18 to 34 years, with tubular breast type II who had bilateral pathology and were treated from 2013 to 2016. They had surgical treatment by method of the clinic. Correction technique consisted of mobilization of the central part of the gland and formation of a glandular flap with vertical and horizontal scorings, which looks like a “chessboard,” that was sufficient to cover the lower pole of the implant. The flap was fixed to the submammary folds with stitches that prevented its reduction and accented a new submammary fold. To underscore the importance of the method and to study the structural features of the vascular bed of tubular breast tissue, a morphological study was conducted. Results: Mean follow-up time was 25 months (range between 13 and 37 mo). The proposed technique achieved good results. Complications (hematoma, circumareolar scarring, and “double-bubble” deformity) were identified in 4 patients. Conclusions: Our morphological study confirmed that tubular breast tissue has increased vascularity due to the vessels with characteristic minor malformation and due to the high restorative potential of the vascular bed. Therefore, an extended glandular flap could be freely mobilized without damaging its blood supply; thus, the flap in most cases covered the implant completely and good aesthetic results were achieved. PMID:27826461

  1. Template synthesized molecularly imprinted polymer nanotube membranes for chemical separations.

    PubMed

    Wang, Hai-Juan; Zhou, Wen-Hui; Yin, Xiao-Fei; Zhuang, Zhi-Xia; Yang, Huang-Hao; Wang, Xiao-Ru

    2006-12-20

    In this report, we describe the synthesis of a molecularly imprinted polymer (MIP) nanotube membrane, using a porous anodic alumina oxide (AAO) membrane by surface-initiated atom transfer radical polymerization (ATRP). The use of a MIP nanotube membrane in chemical separations gives the advantage of high affinity and selectivity. Furthermore, because the molecular imprinting technique can be applied to different kinds of target molecules, ranging from small organic molecules to peptides and proteins, such MIP nanotube membranes will considerably broaden the application of nanotube membranes in chemical separations and sensors. This report also shows that the ATRP route is an efficient procedure for the preparation of molecularly imprinted polymers. Furthermore, the ATRP route works well in its formation of MIP nanotubes within a porous AAO membrane. The controllable nature of ATRP allows the growth of a MIP nanotube with uniform pores and adjustable thickness. Thus, using the same route, it is possible to tailor the synthesis of MIP nanotube membranes with either thicker MIP nanotubes for capacity improvement or thinner nanotubes for efficiency improvement.

  2. Mitogenic action of lysophosphatidic acid in proximal tubular epithelial cells obtained from voided human urine.

    PubMed

    Kumagai, N; Inoue, C N; Kondo, Y; Iinuma, K

    2000-12-01

    Focal tubular cell multiplication at sites on an injured nephron is a critical event in the recovery phase following acute tubular necrosis. During this process, numerous viable tubular cells exfoliate and are shed into the urine. Lysophosphatidic acid (LPA) is generated in the plasma membrane of injured cells and acts as an intercellular mediator of various biological processes, including inflammation, proliferation and repair. In the present study, exfoliated proximal tubule (PT) cells were isolated from human urine and the mitogenic effects of LPA were investigated as a model of repair and proliferation following renal injury. LPA stimulated a 23. 5% increase in DNA synthesis, a 29.4% increase in cell number and an 86.6% decrease in cAMP content. All of these responses were pertussis toxin sensitive, indicating the involvement of G(i)-type G-proteins in LPA signalling. Conversely, the LPA-induced DNA synthesis and the decrease in intracellular cAMP content were insensitive to wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K), suggesting a mitogenic response via PI3K-independent mechanisms. Furthermore, we detected specific mRNA transcripts for the recently cloned human LPA-receptors, endothelial differentiation gene (Edg)-2 and Edg-4 (Edg-2>Edg-4) by reverse transcription-PCR in PT cells. Our data suggest that LPA may behave as a local growth factor in PT cells following tubular injury.

  3. 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...

  4. Modelling and simulation of a pervaporation process using tubular module for production of anhydrous ethanol

    NASA Astrophysics Data System (ADS)

    Hieu, Nguyen Huu

    2017-09-01

    Pervaporation is a potential process for the final step of ethanol biofuel production. In this study, a mathematical model was developed based on the resistance-in-series model and a simulation was carried out using the specialized simulation software COMSOL Multiphysics to describe a tubular type pervaporation module with membranes for the dehydration of ethanol solution. The permeance of membranes, operating conditions, and feed conditions in the simulation were referred from experimental data reported previously in literature. Accordingly, the simulated temperature and density profiles of pure water and ethanol-water mixture were validated based on existing published data.

  5. 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.

  6. 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.

  7. 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.

  8. The AAO-HNS Committee on Hearing and Equilibrium guidelines for the diagnosis and evaluation of therapy in Menière's disease: have they been applied in the published literature of the last decade?

    PubMed

    Thorp, M A; Shehab, Z P; Bance, M L; Rutka, J A

    2003-06-01

    To assess how effectively the American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium (AAO-HNS CHE) guidelines for the diagnosis and evaluation of therapy in Meniere's disease have been applied in the last 11 years of published literature. This was a MedLine-based review. Some 79.7% of papers attempted to use the AAO-HNS CHE guidelines. However, only 50% of these publications managed to use the AAO-HNS CHE criteria in the diagnosis and evaluation of therapy correctly. In order to advance our understanding of this condition, improved application of the AAO-HNS CHE guidelines by authors and editors alike is required in the reporting of results of the therapy of Meniere's disease.

  9. Self-assembled synthesis of 3D Cu(In(1-x)Ga(x))Se2 nanoarrays by one-step electroless deposition into ordered AAO template.

    PubMed

    Zhang, Bin; Zhou, Tao; Zheng, Maojun; Xiong, Zuzhou; Zhu, Changqing; Li, Hong; Wang, Faze; Ma, Li; Shen, Wenzhong

    2014-07-25

    Quaternary nanostructured Cu(In1 - xGax)Se2 (CIGS) arrays were successfully fabricated via a novel and simple solution-based protocol on the electroless deposition method, using a flexible, highly ordered anodic aluminium oxide (AAO) substrate. This method does not require electric power, complicated sensitization processes, or complexing agents, but provides nearly 100% pore fill factor to AAO templates. The field emission scanning electron microscopy (FE-SEM) images show that we obtained uniformly three-dimensional nanostructured CIGS arrays, and we can tailor the diameter and wall thicknesses of the nanostructure by adjusting the pore diameter of the AAO and metal Mo layer. Their chemical composition was determined by energy-dispersive spectroscopy analysis, which is very close to the stoichiometric value. The Raman spectroscopy, x-ray diffraction (XRD) pattern, and transmission electron microscopy (TEM) further confirm the formation of nanostructured CIGS with prominent chalcopyrite structure. The nanostructured CIGS arrays can support the design of low-cost, highlight-trapping, and enhanced carrier collection nanostructured solar cells.

  10. Self-assembled synthesis of 3D Cu(In1 - xGax)Se2 nanoarrays by one-step electroless deposition into ordered AAO template

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Zhou, Tao; Zheng, Maojun; Xiong, Zuzhou; Zhu, Changqing; Li, Hong; Wang, Faze; Ma, Li; Shen, Wenzhong

    2014-07-01

    Quaternary nanostructured Cu(In1 - xGax)Se2 (CIGS) arrays were successfully fabricated via a novel and simple solution-based protocol on the electroless deposition method, using a flexible, highly ordered anodic aluminium oxide (AAO) substrate. This method does not require electric power, complicated sensitization processes, or complexing agents, but provides nearly 100% pore fill factor to AAO templates. The field emission scanning electron microscopy (FE-SEM) images show that we obtained uniformly three-dimensional nanostructured CIGS arrays, and we can tailor the diameter and wall thicknesses of the nanostructure by adjusting the pore diameter of the AAO and metal Mo layer. Their chemical composition was determined by energy-dispersive spectroscopy analysis, which is very close to the stoichiometric value. The Raman spectroscopy, x-ray diffraction (XRD) pattern, and transmission electron microscopy (TEM) further confirm the formation of nanostructured CIGS with prominent chalcopyrite structure. The nanostructured CIGS arrays can support the design of low-cost, highlight-trapping, and enhanced carrier collection nanostructured solar cells.

  11. [Comparative study using AAO-HNS guidelines for conductive hearing loss and Glasgow Benefit Plot to evaluate results of stapes surgery for otosclerosis: results of 129 cases].

    PubMed

    Caces, F; Braccini, F

    2007-01-01

    For surgery of otosclerosis, broughting to the fore interest of crossing informations achieved by using AAO-HNS guidelines for conductive hearing loss and Glasgow Benefit Plot (GBP). Secondary aim: compare stapedotomy with and without veinous interposition. INSTITUTIONS: Referential otologic center in semi-country-side general hospital and private institution in urban zone. retrospective bi-centric study comparing 129 cases of primary surgery for otosclerosis between 1998 and 2004. 3 groups: stapedotomy without veinous interposition (92 cases), stapedotomy with veinous interposition (27 cases), stapedectomy (10 cases). Results given following AAO-HNS guidelines and GBP. variance analysis test and t-Student test (p < 0,05), graphic analysis of inter-aural difference before and after surgery. Main benefit in air conduction (AC) threshold is 23 to 25 dB, no statistical difference between both techniques of stapedotomy. Stapedotomy gives better results than stapedectomy in this serie. Stereophony is achieved in 75% of overall cases with stapedotomy but normal hearing is achieved in only 53% of unilateral pre operative hearing loss. Stapedotomy is a more effective technique in this serie. Crossing informations achieved using AAO-HNS guidelines and GBP leads to give a more realistic and comprehensive understanding to patients who will undergo surgery for otosclerosis.

  12. A Clinical Practice Update on the Latest AAOS/ADA Guideline (December 2012) on Prevention of Orthopaedic Implant Infection in Dental Patients.

    PubMed

    Hamedani, Sh

    2013-03-01

    The American Academy of Orthopaedic Surgeons (AAOS) and the American Dental Association (ADA), along with 10 other academic associations and societies recently (December 2012) published their mutual clinical practice guideline "Prevention of Orthopaedic Implant Infection in Patients Undergoing Dental Procedures." This evidence-based guideline ,detailed in 325 pages, has three recommendations and substitutes the previous AAOS guideline. The new published clinical guideline is a protocol to prevent patients undertaking dental procedures from orthopaedic implant infection. The guideline is developed on the basis of a collaborative systematic review to provide practical advice for training clinicians, dentists and any qualified physicians who need to consider prevention of orthopaedic implant (prosthesis) infection in their patients. This systematic review found no explicit evidence of cause-and-effect relationship between dental procedures and periprosthetic joint infection (PJI). This LTTE wishes to present a vivid summary of AAOS/ADA clinical practice guideline as a clinical update and an academic implementation to inform and assist Iranian competent clinicians and dentists in the course of their treatment decisions, to enrich the value and quality of health care on the latest international basis.

  13. Isoflurane alters proximal tubular cell susceptibility to toxic and hypoxic forms of attack.

    PubMed

    Zager, R A; Burkhart, K M; Conrad, D S

    1999-01-01

    Fluorinated anesthetics can profoundly alter plasma membrane structure and function, potentially impacting cell injury responses. Because major surgery often precipitates acute renal failure, this study assessed whether the most commonly used fluorinated anesthetic, isoflurane, alters tubular cell responses to toxic and hypoxic attack. Mouse proximal tubule segments were incubated under control conditions or with a clinically relevant isoflurane dose. Cell viability (lactate dehydrogenase release), deacylation (fatty acid, such as C20:4 levels), and adenosine triphosphate (ATP) concentrations were assessed under one or more of the following conditions: (a) exogenous phospholipase A2 (PLA2) or C20:4 addition, (b) Ca2+ overload (A23187 ionophore), (c) increased metabolic work (Na ionophore), and (d) hypoxia- or antimycin A-induced attack. Isoflurane's effect on NBD phosphatidylserine uptake (an index of plasma membrane aminophospholipid translocase activity) was also assessed. Isoflurane alone caused trivial deacylation and no lactate dehydrogenase release. However, it strikingly sensitized to both PLA2- and A23187-induced deacylation and cell death. Isoflurane also exacerbated C20:4's direct membrane lytic effect. Under conditions of mild ATP depletion (Na ionophore-induced increased ATP consumption; PLA2-induced mitochondrial suppression), isoflurane provoked moderate/severe ATP reductions and cell death. Conversely, under conditions of maximal ATP depletion (hypoxia, antimycin), isoflurane conferred a modest cytoprotective effect. Isoflurane blocked aminophospholipid translocase activity, which normally maintains plasma membrane lipid asymmetry (that is, preventing its "flip flop"). Isoflurane profoundly and differentially affects tubular cell responses to toxic and hypoxic attack. Direct drug-induced alterations in lipid trafficking/plasma membrane orientation and in cell energy production are likely involved. Although the in vivo relevance of these findings

  14. Tubular solid oxide fuel cell developments

    NASA Astrophysics Data System (ADS)

    Bratton, R. J.; Singh, P.

    An overview of the tubular solid oxide fuel cell (SOFC) development at Westinghouse is presented in this paper. The basic operating principles of SOFC's, evolution in tubular cell design and performance improvement, selection criteria for cell component materials, and cell processing techniques are discussed. The commercial goal is to develop a cell that can operate for 5 to 10 years. Results of cell test operated for more than 50,000 hours are presented. Since 1986, significant progress has been made in the evolution of cells with higher power, lower cost and improved thermal cyclic capability. Also in this period, successively larger multi-kilowatt electrical generators systems have been built and successfully operated for more than 7000 hours.

  15. 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.

  16. Optical analysis of solar energy tubular absorbers.

    PubMed

    Saltiel, C; Sokolov, M

    1982-11-15

    The energy absorbed by a solar energy tubular receiver element for a single incident ray is derived. Two types of receiver elements were analyzed: (1) an inner tube with an absorbing coating surrounded by a semitransparent cover tube, and (2) a semitransparent inner tube filled with an absorbing fluid surrounded by a semitransparent cover tube. The formation of ray cascades in the semitransparent tubes is considered. A numerical simulation to investigate the influence of the angle of incidence, sizing, thickness, and coefficient of extinction of the tubes was performed. A comparison was made between receiver elements with and without cover tubes. Ray tracing analyses in which rays were followed within the tubular receiver element as well as throughout the rest of the collector were performed for parabolic and circular trough concentrating collectors.

  17. Study of hydrodynamic characteristics in tubular photobioreactors.

    PubMed

    Zhang, Qinghua; Wu, Xia; Xue, Shengzhang; Liang, Kehong; Cong, Wei

    2013-02-01

    In this work, the hydrodynamic characteristics in tubular photobioreactors with a series of helical static mixers built-in were numerically investigated using computational fluid dynamics (CFD). The influences of height and screw pitch of the helical static mixer and fluid inlet velocity on the cell trajectories, swirl numbers and energy consumption were examined. In order to verify the actual results for cultivation of microalgae, cultivation experiments of freshwater Chlorella sp. were carried out in photobioreactor with and without helical static mixer built-in at the same time. It was shown that with built-in helical static mixer, the mixing of fluid could be intensified, and the light/dark cycle could also be achieved which is of benefit for the growth of microalgae. The biomass productivity of Chlorella sp. in tubular photobioreactor with helical static mixer built-in was 37.26 % higher than that in the photobioreactor without helical static mixer.

  18. Targeting apoptosis in acute tubular injury.

    PubMed

    Ortiz, Alberto; Justo, Pilar; Sanz, Ana; Lorz, Corina; Egido, Jesús

    2003-10-15

    Recent research has shown that apoptosis and its regulatory mechanisms contribute to cell number regulation in acute renal failure. Acute tubular necrosis is the most frequent form of parenchymal acute renal failure. The main causes are ischemia-reperfusion, sepsis and nephrotoxic drugs. Exogenous factors such as nephrotoxic drugs and bacterial products, and endogenous factors such as lethal cytokines promote tubular cell apoptosis. Such diverse stimuli engage intracellular death pathways that in some cases are stimulus-specific. We now review the role of apoptosis in acute renal failure, the potential molecular targets of therapeutic intervention, the therapeutic weapons to modulate the activity of these targets and the few examples of therapeutic intervention on apoptosis.

  19. 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.

  20. 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.

  1. Tubular solid oxide fuel cell developments

    SciTech Connect

    Bratton, R.J.; Singh, P.

    1995-08-01

    An overview of the tubular solid oxide fuel cell (SOFC) development at Westinghouse is presented in this paper. The basic operating principles of SOFCs, evolution in tubular cell design and performance improvement, selection criteria for cell component materials, and cell processing techniques are discussed. The commercial goal is to develop a cell that can operate for 5 to 10 years. Results of cell test operated for more than 50,000 hours are presented. Since 1986, significant progress has been made in the evolution of cells with higher power, lower cost and improved thermal cyclic capability. Also in this period, successively larger multi-kilowatt electrical generators systems have been built and successfully operated for more than 7000 hours.

  2. Mechanisms in hyperkalemic renal tubular acidosis.

    PubMed

    Karet, Fiona E

    2009-02-01

    The form of renal tubular acidosis associated with hyperkalemia is usually attributable to real or apparent hypoaldosteronism. It is therefore a common feature in diabetes and a number of other conditions associated with underproduction of renin or aldosterone. In addition, the close relationship between potassium levels and ammonia production dictates that hyperkalemia per se can lead to acidosis. Here I describe the modern relationship between molecular function of the distal portion of the nephron, pathways of ammoniagenesis, and hyperkalemia.

  3. Stress concentration factors for dented tubular members

    SciTech Connect

    Buitrago, J.; Hsu, T.M.

    1996-12-31

    This paper presents results of a finite element (FE) study conducted on /tubular members with dents of various geometries, including dents with circular and elliptical cross-sectional shapes. The modeling and analysis procedures are discussed, and stress concentration factors (SCFs) are generated for axial and bending loads in the member. Equations that give SCFs as function of the member size and dent geometry are developed for both load conditions. Then, simplified equations are proposed for structural assessment purposes.

  4. 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)

  5. Distal renal tubular acidosis with hereditary spherocytosis.

    PubMed

    Sinha, Rajiv; Agarwal, Indira; Bawazir, Waleed M; Bruce, Lesley J

    2013-07-01

    Hereditary spherocytosis (HS) and distal renal tubular acidosis (dRTA), although distinct entities, share the same protein i.e. the anion exchanger1 (AE1) protein. Despite this, their coexistence has been rarely reported. We hereby describe the largest family to date with co-existence of dRTA and HS and discuss the molecular basis for the co-inheritance of these conditions.

  6. Sequential Vapor Infiltration Treatment Enhances the Ionic Current Rectification Performance of Composite Membranes Based on Mesoporous Silica Confined in Anodic Alumina.

    PubMed

    Liang, Yanyan; Liu, Zhengping

    2016-12-20

    Ionic current rectification of nanofluidic diode membranes has been studied widely in recent years because it is analogous to the functionality of biological ion channels in principle. We report a new method to fabricate ionic current rectification membranes based on mesoporous silica confined in anodic aluminum oxide (AAO) membranes. Two types of mesostructured silica nanocomposites, hexagonal structure and nanoparticle stacked structure, were used to asymmetrically fill nanochannels of AAO membranes by a vapor-phase synthesis (VPS) method with aspiration approach and were further modified via sequence vapor infiltration (SVI) treatment. The ionic current measurements indicated that SVI treatment can modulate the asymmetric ionic transport in prepared membranes, which exhibited clear ionic current rectification phenomenon under optimal conditions. The ionic current rectifying behavior is derived from the asymmetry of surface conformations, silica species components, and hydrophobic wettability, which are created by the asymmetrical filling type, silica depositions on the heterogeneous membranes, and the condensation of silanol groups. This article provides a considerable strategy to fabricate composite membranes with obvious ionic current rectification performance via the cooperation of the VPS method and SVI treatment and opens up the potential of mesoporous silica confined in AAO membranes to mimic fluid transport in biological processes.

  7. 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

  8. Microfiltration: Membrane development and module design

    NASA Astrophysics Data System (ADS)

    Roesink, Hendrik Dirk Willem

    The development of a type of hydrophilic microfiltration membranes is described. Studies which may result in a design of microfiltration modules containing capillary membranes are presented. The membranes are prepared from a solution containing two polymers and are of flat or cylindrical geometry. Attention is focused an capillary membranes, which are tubular membranes of outer diameter 0.5 to 5 mm, prepared by means of a dry-wet spining process. Different flow conditions of the feed suspension in the modules are described. The most favorable configuration appears to be transverse flow. A model to calculate the pressure drop in the bore of the capillary membrane during filtration and backflushing is presented.

  9. Antimicrobial peptides temporins B and L induce formation of tubular lipid protrusions from supported phospholipid bilayers.

    PubMed

    Domanov, Yegor A; Kinnunen, Paavo K J

    2006-12-15

    The binding of the antimicrobial peptides temporins B and L to supported lipid bilayer (SLB) model membranes composed of phosphatidylcholine and phosphatidylglycerol (4:1, mol/mol) caused the formation of fibrillar protrusions, visible by fluorescent microscopy of both a fluorescent lipid analog and a labeled peptide. Multicolor imaging at low peptide-to-lipid ratios (P/L < approximately 1:5) revealed an initial in-plane segregation of membrane-bound peptide and partial exclusion of lipid from the peptide-enriched areas. Subsequently, at higher P/L numerous flexible lipid fibrils were seen growing from the areas enriched in lipid. The fibrils have diameters <250 nm and lengths of up to approximately 1 mm. Fibril formation reduces the in-plane heterogeneity and results in a relatively even redistribution of bound peptide over the planar bilayer and the fibrils. Physical properties of the lipid fibrils suggest that they have a tubular structure. Our data demonstrate that the peptide-lipid interactions alone can provide a driving force for the spontaneous membrane shape transformations leading to tubule outgrowth and elongation. Further experiments revealed the importance of positive curvature strain in the tubulation process as well as the sufficient positive charge on the peptide (>/=+2). The observed membrane transformations could provide a simplified in vitro model for morphogenesis of intracellular tubular structures and intercellular connections.

  10. Antimicrobial Peptides Temporins B and L Induce Formation of Tubular Lipid Protrusions from Supported Phospholipid Bilayers

    PubMed Central

    Domanov, Yegor A.; Kinnunen, Paavo K. J.

    2006-01-01

    The binding of the antimicrobial peptides temporins B and L to supported lipid bilayer (SLB) model membranes composed of phosphatidylcholine and phosphatidylglycerol (4:1, mol/mol) caused the formation of fibrillar protrusions, visible by fluorescent microscopy of both a fluorescent lipid analog and a labeled peptide. Multicolor imaging at low peptide-to-lipid ratios (P/L < ∼1:5) revealed an initial in-plane segregation of membrane-bound peptide and partial exclusion of lipid from the peptide-enriched areas. Subsequently, at higher P/L numerous flexible lipid fibrils were seen growing from the areas enriched in lipid. The fibrils have diameters <250 nm and lengths of up to ∼1 mm. Fibril formation reduces the in-plane heterogeneity and results in a relatively even redistribution of bound peptide over the planar bilayer and the fibrils. Physical properties of the lipid fibrils suggest that they have a tubular structure. Our data demonstrate that the peptide-lipid interactions alone can provide a driving force for the spontaneous membrane shape transformations leading to tubule outgrowth and elongation. Further experiments revealed the importance of positive curvature strain in the tubulation process as well as the sufficient positive charge on the peptide (≥+2). The observed membrane transformations could provide a simplified in vitro model for morphogenesis of intracellular tubular structures and intercellular connections. PMID:16997872

  11. 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

  12. Behavior of horizontally curved steel tubular-flange bridge girders

    NASA Astrophysics Data System (ADS)

    Fan, Zhuo

    A new type of curved steel bridge girder, called a curved tubular-flange girder, with rectangular tubes as flanges, is proposed and studied in this dissertation. A curved steel tubular-flange girder has much larger torsional stiffness than a curved I-girder and less potential for cross section distortion than a curved box-girder. Therefore, it has potential advantages compared to curved I-girders and box-girders. A theoretical analysis method for systems of curved tubular-flange girders braced by cross frames is presented. A stress analysis method for tubular-flange girders is also provided. The behavior of curved tubular-flange girder systems is studied using the theoretical analysis method and compared to the behavior of the corresponding curved I-girder systems. A parametric study is performed using the theoretical analysis method to investigate the effects of geometric parameters on the behavior of curved tubular-flange girder systems. The studied parameters include tubular-flange width, tubular-flange depth, cross section depth, girder curvature, and the number of cross frames. Finite element analyses are conducted to verify the theoretical analysis method, to study the behavior of a curved tubular-flange girder system under dead load, and to study the behavior of a curved tubular-flange girder system with a composite concrete deck under dead and live load. The study shows that a curved tubular-flange girder system develops much less warping normal stress and cross section rotation than a corresponding curved I-girder system. The difference is especially significant for a single curved girder under its own weight, suggesting that curved tubular-flange girders would be much easier to transport and erect than curved I-girders. As girder curvature increases, the rate of increase in the stresses and displacements for a single I-girder is much greater than for a single curved tubular-flange girder. Smaller cross frame forces develop in a tubular-flange girder

  13. Physiological pH. Effects on posthypoxic proximal tubular injury.

    PubMed

    Zager, R A; Schimpf, B A; Gmur, D J

    1993-04-01

    After O2 deprivation, tissue acidosis rapidly self-corrects. This study assessed the effect of this pH correction on the induction, and pathways, of posthypoxic proximal tubular injury. In addition, ways to prevent the resultant injury were explored. Isolated rat proximal tubular segments (PTSs) were subjected to hypoxia/reoxygenation (50/30 or 30/50 minutes) under the following incubation conditions: 1) continuous pH 7.4, 2) continuous pH 6.8, or 3) hypoxia at pH 6.8 and reoxygenation at pH 7.4 (NaHCO3 or Tris base addition). Continuously oxygenated PTSs maintained under these same pH conditions served as controls. Lethal cell injury was assessed by lactate dehydrogenase (LDH) release. pH effects on several purported pathways of hypoxia/reoxygenation injury were also assessed (ATP depletion, lipid peroxidation, and membrane deacylation). Acidosis blocked hypoxic LDH release (pH 7.4, 50 +/- 2%; pH 6.8, 6 +/- 1%) without mitigating membrane deacylation or ATP depletion. During reoxygenation, minimal LDH was released (3-5%) if pH was held constant. However, if posthypoxic pH was corrected, immediate (< or = 5 minutes) and marked cell death (e.g., 55 +/- 3% with Tris) occurred. This was dissociated from lipid peroxidation or new deacylation, and it was preceded by a depressed ATP/ADP ratio (suggesting an acidosis-associated defect in hypoxic/posthypoxic cell energetics). Realkalinization injury was not inevitable, since it could be substantially blocked by 1) posthypoxic glycine addition, 2) transient posthypoxic hypothermia, or 3) allowing a 10-minute reoxygenation (cell recovery) period before base addition. Neither mannitol nor graded buffer Ca2+ deletion conferred protection. Acute pH correction caused no injury to continuously oxygenated PTSs. Conclusions are as follows: 1) Posthypoxic "pH shock" causes virtually immediate cell death, not by causing de novo injury but, rather, by removing the cytoprotective effect of acidosis. 2) This injury can be prevented by a

  14. 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.

  15. Renal tubular acidosis: an immunopathological study on four patients

    PubMed Central

    Pasternack, A.; Linder, E.

    1970-01-01

    Renal biopsies and sera of four patients with distal renal tubular acidosis were examined. The findings consisted of immunoglobulin containing mononuclear cellular infiltrates around the distal tubules, bound immunoglobulin and complement in tubules. The sera of the patients contained antibodies reacting with various tissue antigens, among them renal tubular antigens. The results suggest that autoimmunity was involved in the pathogenesis of the renal tubular acidosis in these patients. ImagesFig. 1Fig. 2 PMID:5202740

  16. 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).

  17. Renal tubular acidosis in chronic liver disease

    PubMed Central

    Golding, Peter L.

    1975-01-01

    Renal tubular acidosis of the gradient or classic type, thought to be due to a disorder of the distal tubule, has been found to occur in 32% of 117 patients with chronic liver disease. Whilst the cause of this disorder is probably multifactorial, immunological mechanisms are considered to play a major role. The presence of this disorder might well be a cause, rather than the result of, the various electrolyte abnormalities seen in patients with chronic liver disease. ImagesFig. 1Fig. 6 PMID:1234340

  18. Connection pad design for underwater tubular structures

    SciTech Connect

    Tsai, C.L.; Feng, Z.; Grantham, J.A. . Dept. of Welding Engineering); Soisson, L. )

    1990-01-01

    This paper reports on research to optimize the connection pad assembly design for different types of loading conditions, which means minimizing the stresses in the wet welds and maximizing the energy absorption of the connection pad. The tubular geometry of the connection pad does not allow stress field analysis by the traditional strength-of-materials method. The authors discuss how, using the finite element method to analyze the stress contributions and the energy absorbed by the pad, the optimum pad dimensions could be determined for different types of loads.

  19. Intraductal tubular neoplasms of the bile ducts.

    PubMed

    Katabi, Nora; Torres, Javiera; Klimstra, David S

    2012-11-01

    Although most tumors of the bile ducts are predominantly invasive, some have an exophytic pattern within the bile ducts; these intraductal papillary neoplasms usually have well-formed papillae at the microscopic level. In this study, however, we describe a novel type of intraductal neoplasm of the bile ducts with a predominantly tubular growth pattern and other distinctive features. Ten cases of biliary intraductal neoplasms with a predominantly tubular architecture were identified in the files of the Pathology Department at Memorial Sloan-Kettering Cancer Center from 1983 to 2006. For each of these cases we studied the clinical presentation, histologic and immunohistochemical features (9 cases only), and the clinical follow-up of the patients. Three male and 7 female patients (38 to 78 y) presented with obstructive jaundice or abdominal pain. Eight of the patients underwent a partial hepatectomy; 2 underwent a laparoscopic bile duct excision, followed by a pancreatoduodenectomy in one of them. The tumors range in size from 0.6 to 8.0 cm. The intraductal portions of the tumors (8 intrahepatic, 1 extrahepatic hilar, 1 common bile duct) were densely cellular and composed of back-to-back tubular glands and solid sheets with minimal papillary architecture. The cells were cuboidal to columnar with mild to moderate cytologic atypia. Foci of necrosis were present in the intraductal component in 6 cases. An extraductal invasive carcinoma component was present in 7 cases, composing <25% of the tumor in 4 cases, and >75% in 1 case. It was observed by immunohistochemical analysis that the tumor cells expressed CK19, CA19-9, MUC1, and MUC6 in most cases and that SMAD4 expression was retained. MUC2, MUC5AC, HepPar1, synaptophysin, chromogranin, p53, and CA125 were negative in all cases and most were negative for CEA-M and B72.3. Four patients were free of tumor recurrence after 7 to 85 months (average, 27 mo). Four patients with an invasive carcinoma component suffered

  20. 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.

  1. 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.

  2. Mesangial cells initiate compensatory tubular cell hypertrophy.

    PubMed

    Sinuani, I; Beberashvili, I; Averbukh, Z; Cohn, M; Gitelman, I; Weissgarten, J

    2010-01-01

    Unilateral nephrectomy results in compensatory renal growth, in which both the size and the functional capacity of the remaining kidney are increased. The functional adaptation to the removal of the contralateral kidney consists mostly of an increase in the glomerular filtration rate of the remaining kidney, and hypertrophy of cells comprising the nephron, mainly of the proximal tubular cells. Although the phenomenon of single kidney hypertrophy has been known for the past thousand years and despite intensive research over the past century, the mechanism of this process still remains unclear. The present article reviews the role of mesangial cells in compensatory renal hypertrophy. 2010 S. Karger AG, Basel.

  3. Selective uptake of (/sup 3/H)arachidonic acid into the dense tubular system of human platelets

    SciTech Connect

    Laposata, M.; Krueger, C.M.; Saffitz, J.E.

    1987-09-01

    We have used quantitative electron microscopic autoradiography to characterize the subcellular distribution of arachidonoyl phospholipids following brief (5 minutes) exposure of unstimulated human platelets to (/sup 3/H)arachidonic acid. Labeled arachidonate was taken up rapidly and incorporated into phospholipids. Phospholipid radioactivity was preserved and spatially fixed during tissue processing for electron microscopy. Analysis of autoradiographs showed that following a brief exposure to 750 nmol/L (/sup 3/H)arachidonate, there is selective labeling of an internal membrane compartment composed of the dense tubular system and the open canalicular system. The plasma membrane, platelet granules, and nonmembranous cytoplasm were not labeled. Since the open canalicular system is continuous with the plasma membrane and since phospholipids in continuous membranes are freely diffusible, our observations indicate that (/sup 3/H)arachidonate was incorporated into phospholipids within the dense tubular system and not the open canalicular system. Thus, the dense tubular system, known to contain cyclooxygenase activity, incorporates arachidonate selectively following brief exposure to this fatty acid, presumably to concentrate it in proximity to enzymes for icosanoid synthesis.

  4. Tubular Obstruction Leads to Progressive Proximal Tubular Injury and Atubular Glomeruli in Polycystic Kidney Disease

    PubMed Central

    Galarreta, Carolina I.; Grantham, Jared J.; Forbes, Michael S.; Maser, Robin L.; Wallace, Darren P.; Chevalier, Robert L.

    2015-01-01

    In polycystic kidney disease (PKD), renal parenchyma is destroyed by cysts, hypothesized to obstruct nephrons. A signature of unilateral ureteral obstruction, proximal tubular atrophy leads to formation of atubular glomeruli. To determine whether this process occurs in PKD, kidneys from pcy mice (moderately progressive PKD), kidneys from cpk mice (rapidly progressive PKD), and human autosomal dominant PKD were examined in early and late stages. Integrity of the glomerulotubular junction and proximal tubular mass were determined in sections stained with Lotus tetragonolobus lectin. Development of proximal tubular atrophy and atubular glomeruli was determined in serial sections of individual glomeruli. In pcy mice, most glomerulotubular junctions were normal at 20 weeks, but by 30 weeks, 56% were atrophic and 25% of glomeruli were atubular; glomerulotubular junction integrity decreased with increasing cyst area (r = 0.83, P < 0.05). In cpk mice, all glomerulotubular junctions were normal at 10 days, but by 19 days, 26% had become abnormal. In early-stage autosomal dominant PKD kidneys, 50% of glomeruli were atubular or attached to atrophic tubules; in advanced disease, 100% were abnormal. Thus, proximal tubular injury in cystic kidneys closely parallels that observed with ureteral obstruction. These findings support the hypothesis that, in renal cystic disorders, cyst-dependent obstruction of medullary and cortical tubules initiates a process culminating in widespread destruction of proximal convoluted tubules at the glomerulotubular junction. PMID:24815352

  5. Acute toxicity reduction and toxicity identification in pigment-contaminated wastewater during anaerobic-anoxic-oxic (A/A/O) treatment process.

    PubMed

    Deng, Minjie; Zhang, Ying; Quan, Xie; Na, Chunhong; Chen, Shuo; Liu, Wei; Han, Shuping; Masunaga, Shigeki

    2017-02-01

    In China, a considerable part of industrial wastewater effluents are discharged into the municipal wastewater treatment plants (WWTPs) after pretreatment in their own wastewater treatment plants. Even though the industrial effluents meet the professional emission standards, many micro-pollutants still remained, and they could be resistant in the municipal WWTPs with conventional activated sludge process. Pigment wastewater was chosen in this study, and the acute toxicity reduction and identification of the pigment-contaminated wastewater treated by the conventional anaerobic-anoxic-oxic (A/A/O) process were evaluated. Results indicated that the raw pigment-contaminated wastewater was acutely toxic to Photobacterium phosphoreum (P. phosphoreum), Daphnia magna (D. magna) and Danio rerio (D. rerio). The acute toxicity was decreased in some degree after A/A/O treatment, but the final effluent still exhibited acute toxicity to D. magna and D. rerio with the toxic units (TU) of 1.1 and 2.0, respectively. Chemical analyses showed the presence of various refractory and toxic nitrogen-containing polycyclic and heterocyclic compounds in the pigment-contaminated wastewater. Toxicity identification by combining chemical analyses and correlation analysis showed that N-containing refractory organic toxicants were the main toxicity source for the pigment-contaminated wastewater, and several toxicants showed significant correlation with P. phosphoreum and D. magna. This study indicated that the A/A/O process was not efficient for pigment-contaminated wastewater treatment, and it was irradiative for technology improvement in the WWTPs receiving pretreated industrial wastewater effluents.

  6. Highly sensitive MOS photodetector with wide band responsivity assisted by nanoporous anodic aluminum oxide membrane.

    PubMed

    Chen, Yungting; Cheng, Tzuhuan; Cheng, Chungliang; Wang, Chunhsiung; Chen, Chihwei; Wei, Chihming; Chen, Yangfang

    2010-01-04

    A new approach for developing highly sensitive MOS photodetector based on the assistance of anodic aluminum oxide (AAO) membrane is proposed, fabricated, and characterized. It enables the photodetector with the tunability of not only the intensity but also the range of the response. Under a forward bias, the response of the MOS photodetector with AAO membrane covers the visible as well as infrared spectrum; however, under a reverse bias, the near-infrared light around Si band edge dominates the photoresponse. Unlike general MOS photodetectors which only work under a reverse bias, our MOS photodetectors can work even under a forward bias, and the responsivity at the optical communication wavelength of 850nm can reach up to 0.24 A/W with an external quantum efficiency (EQE) of 35%. Moreover, the response shows a large enhancement factor of 10 times at 1050 nm under a reverse bias of 0.5V comparing with the device without AAO membrane. The underlying mechanism for the novel properties of the newly designed device has been proposed.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Role of the glomerular-tubular imbalance with tubular predominance in the arterial hypertension pathophysiology.

    PubMed

    Fox, María Ofelia Barber; Gutiérrez, Ernesto Barber

    2013-09-01

    In previous investigations we caused renal tubular reabsorption preponderance relating to the glomerular filtration (Glomerular-tubular imbalance) and we observed that this fact conducted to volume expansion and development of arterial hypertension, in rats that previously were normotens. We based on this evidence and other which are reflected in the literature arrived at the following hypothesis: a greater proportion of tubular reabsorption relating to the filtered volume is the base of the establishment of the glomerular-tubular imbalance with tubular predominance (GTI-T), which favors to the Na(+)-fluid retention and volume expansion. All of which conduced to arterial hypertension. These facts explain a primary hypertensive role of the kidney, consistent with the results of renal transplants performed in different lines of hypertensive rats and their respective controls and in humans: hypertension can be transferred with the kidney. GTI-T aims to be, a common phenomenon involved in the hypertension development in the multiple ways which is manifested the hypertensive syndrome. In secondary hypertension, GTI-T is caused by significant disruptions of hormone secretions that control renal function, or obvious vascular or parenchymal damage of these organs. In primary hypertension the GTI-T has less obvious causes inherently developed in the kidney, including humoral, cellular and subcellular mechanisms, which may insidiously manifest under environmental factors influence, resulting in insidious development of hypertension. This would explain the state of prehypertension that these individuals suffer. So it has great importance to study GTI-T before the hypertension is established, because when hypertensive state is established, other mechanisms are installed and they contribute to maintain the hypertension. Our hypothesis may explaining the inability of the kidneys to excrete salt and water in hypertension, as Guyton and colleagues have expressed and constitutes a

  12. Effects of cumene hydroperoxide on cellular cation composition in frog kidney proximal tubular cells.

    PubMed

    Petrovic, S; Cemerikic, D

    2000-06-01

    Effects of cumene hydroperoxide were studied on the peritubular membrane potential and cellular cation composition in frog kidney proximal tubular cells. After perfusion of isolated frog kidneys for 30 min with 1.3x10(-4) mol l(-1) cumene hydroperoxide Ringer solution, the peritubular membrane potential gradually declined. The ouabain-like effects were demonstrated on cell Na and K activities after 1 h of perfusion with cumene hydroperoxide. The peritubular apparent transference number for potassium was decreased. Intracellular pH was not altered in the presence of cumene hydroperoxide. Intracellular free Ca(2+) concentration increased slowly and moderately. The concentration of the malondialdehyde in the kidney homogenates, measured as an index of lipid peroxidation, was increased. A previously observable effect of cumene hydroperoxide on the peritubular membrane potential was prevented by oxygen radical scavengers.

  13. Gravity-flow open tubular cation chromatography.

    PubMed

    Kubán, Petr; Pelcová, Pavlína; Kubán, Vlastimil; Klakurková, Lenka; Dasgupta, Purnendu K

    2008-08-01

    We describe ion chromatography (IC) on open tubular cation exchange columns with a controllable capacity multilayered stationary phase architecture. The columns of relatively large bore (75 microm id) are fabricated by coating fused-silica capillaries with multiple layers of poly(butadiene-maleic acid) (PBMA) copolymer and crosslinking the deposited layers by thermally initiated radical polymerisation. Column capacity increases in a predictable manner with increase in the number of successively coated layers. Gravity flow with a modest head (< 2 m) can provide the desired separations within a reasonable period. We provide a minimalist configuration where no suppression is used, the sample is injected hydrodynamically as in CE, and detection is accomplished by an inexpensive homebuilt contactless conductivity detector or a capacitance to voltage digital converter. A 1 m long 75 microm bore column coated with two layers of PBMA allows gravity-flow open tubular IC to separate four alkali cations in < 10 min with a 1 mM tartaric acid (TA) eluent. Simultaneous separation of alkali and alkaline earth metal cations can be accomplished in less than 25 min using 1.75 mM pyridinedicarboxylic acid as an eluent. Contactless conductometric detection (C(4)D) allows LODs down to 150 nmol/L, corresponding to 30 fmol injections. Analysis of real water samples is demonstrated.

  14. Tubular photobioreactor design for algal cultures.

    PubMed

    Molina, E; Fernández, J; Acién, F G; Chisti, Y

    2001-12-28

    Principles of fluid mechanics, gas-liquid mass transfer, and irradiance controlled algal growth are integrated into a method for designing tubular photobioreactors in which the culture is circulated by an airlift pump. A 0.2 m(3) photobioreactor designed using the proposed approach was proved in continuous outdoor culture of the microalga Phaeodactylum tricornutum. The culture performance was assessed under various conditions of irradiance, dilution rates and liquid velocities through the tubular solar collector. A biomass productivity of 1.90 g l(-1) d(-1) (or 32 g m(-2) d(-1)) could be obtained at a dilution rate of 0.04 h(-1). Photoinhibition was observed during hours of peak irradiance; the photosynthetic activity of the cells recovered a few hours later. Linear liquid velocities of 0.50 and 0.35 m s(-1) in the solar collector gave similar biomass productivities, but the culture collapsed at lower velocities. The effect of dissolved oxygen concentration on productivity was quantified in indoor conditions; dissolved oxygen levels higher or lower than air saturation values reduced productivity. Under outdoor conditions, for given levels of oxygen supersaturation, the productivity decline was greater outdoors than indoors, suggesting that under intense outdoor illumination photooxidation contributed to loss of productivity in comparison with productivity loss due to oxygen inhibition alone. Dissolved oxygen values at the outlet of solar collector tube were up to 400% of air saturation.

  15. Tubular solid oxide fuel cell prospect

    SciTech Connect

    Veyo, S.E.

    1996-05-01

    Driven by technological achievement and rational projection of commercial product cost, expectations for tubular SOFC commercialization are improving. Tubular SOFCs have surpassed 7 yrs operation and have recently demonstrated remarkable toughness in thermal cycling. Customer-owned systems with 25 kW stacks utilizing air electrode supported (AES) cells continue to operate directly on natural gas without degradation after multiple thermal cycles and over 4000 hrs operation. AES cell operation at elevated pressure corroborates theoretical estimates of performance gain without evidence of deleterious effect. Commercial class AES cell of 22 mm dia and 1500 mm length, is now in production for application to 100 kW, 50% efficient (ac/LHV), atmospheric pressure systems. This same cell applied to pressurized systems in combination with conventional turbo machinery (gas turbines) can yield an efficiency approaching 70% for power plants as small as 5 MW. Total installed system cost for commercial 5 MW SOFC/CT units for distributed power generation and on-site cogeneration should approach $1000/kW. A major challenge is formation of funded projects to demonstrate at the turn of the century prototype MW class SOFC/CT combined cycle power plants and to complete the development of commercial fuel cell manufacturing processes.

  16. 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

  17. 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.

  18. SNX-BAR proteins in phosphoinositide-mediated, tubular-based endosomal sorting.

    PubMed

    van Weering, Jan R T; Verkade, Paul; Cullen, Peter J

    2010-06-01

    The endocytic network is morphologically characterized by a wide variety of membrane bound compartments that are able to undergo dynamic re-modeling through tubular and vesicular structures. The precise molecular mechanisms governing such re-modeling, and the events that co-ordinated this with the major role of endosomes, cargo sorting, remain unclear. That said, recent work on a protein family of sorting nexins (SNX) - especially a subfamily of SNX that contain a BAR domain (SNX-BARs) - has begun to shed some much needed light on these issues and in particular the process of tubular-based endosomal sorting. SNX-BARs are evolutionary conserved in endosomal protein complexes such as retromer, where they co-ordinate membrane deformation with cargo selection. Furthermore a central theme emerges of SNX-BARs linking the forming membrane carrier to cytoskeletal elements for transport through motor proteins such as dynein. By studying these SNX-BARs, we are gaining an increasingly detailed appreciation of the mechanistic basis of endosomal sorting and how this highly dynamic process functions in health and disease.

  19. Localization of platelet prostaglandin production in the platelet dense tubular system.

    PubMed Central

    Gerrard, J. M.; White, J. G.; Rao, G. H.; Townsend, D.

    1976-01-01

    Platelet production of 12L-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 8-(1-hydroxy-3-oxopropyl)-9, 12L-dihydroxy-5,10-heptadecadienoic acid (PHD), two metabolites of the prostaglandin cyclic endoperoxides PGG2 and PGH2, was found in this investigation to occur primarily in a platelet microsomal fraction consisting almost exclusively of membranes. To further localize the membrane site of platelet prostaglandin biosynthesis, the present study has used a cytochemical technique employing 3,3'-diaminobenzidine as an oxidizable substrate. The reaction product was found to localize in the platelet dense tubular system. Formation of the reaction product was inhibited by aminotriazole. In similar concentrations, aminotriazole inhibited collagen and arachidonic acid aggregation, the second wave of ADP and epinephrine aggregation, but failed to inhibit aggregation by PGG2 and A23187. A study of the mechanism of action of aminotriazole revealed inhibition of formation of HHT and PHD. The results localize platelet prostaglandin biosynthesis to the membranes of the dense tubular system. Images Figure 5 Figure 6 Figures 1-2 Figure 3 and 4 PMID:1266944

  20. A novel tubular microbial electrolysis cell for high rate hydrogen production

    NASA Astrophysics Data System (ADS)

    Guo, Kun; Prévoteau, Antonin; Rabaey, Korneel

    2017-07-01

    Practical application of microbial electrolysis cells (MECs) for hydrogen production requires scalable reactors with low internal resistance, high current density, and high hydrogen recovery. This work reports a liter scale tubular MEC approaching these requirements. The tubular cell components (a platinum-coated titanium mesh cathode, an anion exchange membrane, and a pleated stainless steel felt anode) were arranged in a concentric configuration. The reactor had a low internal resistance (0.325 Ω, 19.5 mΩ m2) due to the high conductivity of the electrodes, a compact reactor configuration, and proper mixing. With acetate as electron donor, the MEC achieved a volumetric current density of 654 ± 22 mA L-1 (projected current density, 1.09 ± 0.04 mA cm-2) and a volumetric hydrogen production rate of 7.10 ± 0.01 L L-1 d-1 at an applied voltage of 1 V. The reactor also showed high hydrogen recovery (∼100%), high hydrogen purity (>98%), and excellent operational stability during the 3 weeks of operation. These results demonstrated that high hydrogen production rate could be achieved on larger scale MEC and this tubular MEC holds great potential for scaling up.

  1. Micro-tubular solid oxide fuel cells with graded anodes fabricated with a phase inversion method

    NASA Astrophysics Data System (ADS)

    Zhao, Ling; Zhang, Xiaozhen; He, Beibei; Liu, Beibei; Xia, Changrong

    Micro-tubular proton-conducting solid oxide fuel cells (SOFCs) are developed with thin film BaZr 0.1Ce 0.7Y 0.1Yb 0.1O 3- δ (BZCYYb) electrolytes supported on Ni-BZCYYb anodes. The substrates, NiO-BZCYYb hollow fibers, are prepared by an immersion induced phase inversion technique. The resulted fibers have a special asymmetrical structure consisting of a sponge-like layer and a finger-like porous layer, which is propitious to serving as the anode supports for micro-tubular SOFCs. The fibers are characterized in terms of porosity, mechanical strength, and electrical conductivity regarding their sintering temperatures. To make a single cell, a dense BZCYYb electrolyte membrane about 20 μm thick is deposited on the hollow fiber by a suspension-coating process and a porous Sm 0.5Sr 0.5CoO 3 (SSC)-BZCYYb cathode is subsequently fabricated by a slurry coating technique. The micro-tubular proton-conducting SOFC generates a peak power density of 254 mW cm -2 at 650 °C when humidified hydrogen is used as the fuel and ambient air as the oxidant.

  2. 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

  3. Fabrication of novel nanomaterials for polymer electrolyte membrane fuel cells and self-cleaning applications

    NASA Astrophysics Data System (ADS)

    Zhang, Lei

    Materials scientists have embraced nanoscale materials as allowing new degrees of freedom in materials design, as well as producing completely new and enhanced properties compared with conventional materials. However, most nanofabrication methods are tedious and expensive, or require extreme conditions. This thesis presents efficient methods for generating nanostructured materials under relatively mild chemistry and experimental conditions. The basis of most of this work is porous anodic aluminum oxide (p-AAO) membranes, which have hexagonally close-packed pores and were fabricated following a two-step aluminum anodization procedure. Partially removing the barrier layer of a p-AAO membrane enabled the preparation of silver nanorod arrays using a very simple electrodepostition procedure. One dimensional (1-D) alumina nanostructures were also electrochemically synthesized on the surface of a p-AAO membrane by carefully controlling the anodization parameters. Polyacrylonitrile nanofibers containing platinum salt were fabricated by polymerization of acrylonitrile in p-AAO templates. Subsequent pyrolysis resulted in carbon nanofibers wherein the platinum salt is reduced in-situ to elemental Pt. The Pt nanoparticles are dispersed throughout the carbon nanofibers, have a narrow size range, and are single crystals. Rotating disc electrode voltammetry suggests that the dispersion of Pt nanocrystals in the carbon nanofiber matrix should exhibit excellent electrocatalytic activity. The preparation of catalyst ink and the construction of membrane-electrode-assembly need to be optimized to get better performance in polymer electrolyte membrane fuel cells. Platinum nanoparticles embedded in carbon fibers were also prepared using electrospinning. The prepared platinum nanoparticles are narrowly distributed in size and well dispersed in the carbon matrix. This method can provide a large yield of products with a simple setup and procedure. 2-D arrays of nanopillars made from

  4. The effect of wellbore curvature on tubular buckling and lockup

    SciTech Connect

    Wu, J.; Juvkam-Wold, H.C.

    1994-12-31

    This paper describes sinusoidal and helical buckling of tubulars in curved wellbores (such as the build section of horizontal wells) and the effect on `lockup` of tubulars when drilling horizontal or extended-reach wells. New buckling load equations are derived to properly predict sinusoidal and helical buckling of tubulars in such wellbores. The results show that the buckling loads to ultimate sinusoidal and helical buckling of tubulars in curved wellbores are usually much larger than those in straight wellbores. This is because the curved wellbore tends to hold the axially compressed tubular against the outer-curve side of the wellbore. It is difficult to buckle a tubular into a sinusoidal or helical shape in curved wellbores, unless a very high axial compressive load is applied. The risk of tubular lockup when chilling horizontal or extended-reach wells is therefore reduced, because there is likely to be very little, if any, tubular buckling in the curved wellbore. The buckling loads derived in this paper also agree with those in straight wellbores when wellbore curvature approaches zero. Small scale laboratory experiments confirmed the theoretically derived buckling loads.

  5. The tubular "cookie cutter" bullet: a unique projectile.

    PubMed

    Nolte, K B

    1990-11-01

    Recently marketed PMC (Pan Metal Corporation) Ultramag tubular hollow point ammunition is uniquely constructed with a two-part projectile composed of a tubular copper bullet and a Teflon wad. A fatal gunshot wound with this ammunition is described. A unique radiographic pattern and the results of test firing are also presented.

  6. Endocytosis of wheat germ agglutinin binding sites from the cell surface into a tubular endosomal network.

    PubMed

    Raub, T J; Koroly, M J; Roberts, R M

    1990-04-01

    By using fluorescence and electron microscopy, the endocytic pathway encountered by cell surface components after they had bound wheat germ agglutinin (WGA) was visualized. The majority of these components are thought to consist of sialylated glycoproteins (HMWAG) that represent a subpopulation of the total cell surface proteins but most of the externally disposed plasma membrane proteins of the cell. Examination of semi-thin sections by medium- and high-voltage electron microscopy revealed the three-dimensional organization of vesicular and tubular endosomes. Binding of either fluorescein isothiocyanate-, horseradish peroxidase-, or ferritin-conjugated WGA to cells at 4 degrees C showed that the HMWAG were distributed uniformly over the cell surface. Warming of surface-labeled cells to 37 degrees C resulted in the endocytosis of WGA into peripheral endosomes via invagination of regions of both coated and uncoated membrane. The peripheral endosome appeared as isolated complexes comprising a vesicular element (300-400 nm diam.) surrounded by and continuous with tubular cisternae (45-60 nm diam.), which did not interconnect the endosomes. After 30 min or more label also became localized in a network of anastomosing tubules (45-60 nm diam.) that were located in the centrosomal region of the cell. Endocytosed WGA-HMWAG complexes did not become associated with cisternae of the Golgi apparatus, although tubular and vesicular endosomes were noted in the vicinity of the trans-Golgi region. The accumulation of WGA-HMWAG in the endosomes within the centrosomal region was inhibited when cells were incubated at 18 degrees C. None of these compartments contained acid phosphatase activity, a result that is consistent with other data that the HMWAG do not pass through lysosomes initially. The kinetics of labeling were consistent with the interpretation that recycling of most of the WGA binding surface glycoproteins occurred rapidly from early peripheral endosomes followed by the

  7. Specific estrogen-induced cell proliferation of cultured Syrian hamster renal proximal tubular cells in serum-free chemically defined media

    SciTech Connect

    Oberley, T.D.; Lauchner, L.J.; Pugh, T.D.; Gonzalez, A.; Goldfarb, S. ); Li, S.A.; Li, J.J. )

    1989-03-01

    It has long been recognized that the renal proximal tubular epithelium of the hamster is a bona fide estrogen target tissue. The effect of estrogens on the growth of proximal tubule cell explants and dissociated single cells derived from these explant outgrowths has been studied in culture. Renal tubular cells were grown on a PF-HR-9 basement membrane under serum-free chemically defined culture conditions. At 7-14 days in culture, cell number was enhanced 3-fold in the presence of either 17{beta}-estradiol or diethylstilbestrol. A similar 3-fold increase in cell number was also seen at 1 nM 17{beta}-estradiol in subcultured dissociated single tubular cells derived from hamster renal tubular explant outgrowths at 21 days in culture. Concomitant exposure of tamoxifen at 3-fold molar excess in culture completely abolished the increase in cell number seen with 17{beta}-estradiol. The proliferation effect of estrogens on proximal tubular cell growth appears to be species specific since 17{beta}-estradiol did not alter the growth of either rat or guinea pig proximal tubules in culture. In addition, at 7-10 days in culture in the presence of 17{beta}-estradiol, ({sup 3}H)thymidine labeling of hamster tubular cells was enhanced 3-fold. These results clearly indicate that estrogens can directly induce primary epithelial cell proliferation at physiologic concentrations and provide strong additional evidence for an important hormonal role in the neoplastic transformation of the hamster kidney.

  8. Probing the highly efficient room temperature ammonia gas sensing properties of a luminescent ZnO nanowire array prepared via an AAO-assisted template route.

    PubMed

    Kumar, Nagesh; Srivastava, A K; Nath, R; Gupta, Bipin Kumar; Varma, G D

    2014-04-21

    Here, we report the facile synthesis of a highly ordered luminescent ZnO nanowire array using a low temperature anodic aluminium oxide (AAO) template route which can be economically produced in large scale quantity. The as-synthesized nanowires have diameters ranging from 60 to 70 nm and length ∼11 μm. The photoluminescence spectrum reveals that the AAO/ZnO assembly has a strong green emission peak at 490 nm upon excitation at a wavelength of 406 nm. Furthermore, the ZnO nanowire array-based gas sensor has been fabricated by a simple micromechanical technique and its NH3 gas sensing properties have been explored thoroughly. The fabricated gas sensor exhibits excellent sensitivity and fast response to NH3 gas at room temperature. Moreover, for 50 ppm NH3 concentration, the observed value of sensitivity is around 68%, while the response and recovery times are 28 and 29 seconds, respectively. The present synthesis technique to produce a highly ordered ZnO nanowire array and a fabricated gas sensor has great potential to push the low cost gas sensing nanotechnology.

  9. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-07-01

    In the present quarter, oxygen transport perovskite ceramic membranes 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.

  10. Flexible tubular replicas of abdominal aortic aneurysms.

    PubMed

    Berry, E; Marsden, A; Dalgarno, K W; Kessel, D; Scott, D J A

    2002-01-01

    The aim of this study was to manufacture life-size, flexible, tubular replicas of human abdominal aortic aneurysms and the associated vasculature, suitable for use in a training simulator for endovascular procedures. Selective laser sintering was used to create a geometrically correct master model for each of ten anatomical variations. The masters were used to generate flexible latex replicas. The use of the replicas in the training simulator was demonstrated. In total ten silicone rubber models were produced. When connected into the training simulator and perfused at arterial pressure it was possible to deploy an endovascular stent under fluoroscopic control and to perform angiography. The study has shown that conventional rapid prototyping technology can be used to manufacture flexible, radiolucent replicas which provide a realistic training environment for endovascular procedures.

  11. Inherited renal tubular defects with hypokalemia.

    PubMed

    Muthukrishnan, J; Modi, K D; Kumar, P Jagdish; Jha, Ratan

    2009-03-01

    Bartter's and Gitelman's syndrome are two ends of a spectrum of inherited renal tubular disorders that present with hypokalemic metabolic alkalosis of varying severity. Clinical features and associated calcium and magnesium ion abnormalities are used to diagnose these cases after excluding other commoner causes. We report on two cases, the first being a young boy, born of pregnancy complicated by polyhydramnios, who had classical dysmorphic features, polyuria, hypokalemia and hypercalciuria and was diagnosed as having Bartter's syndrome. The second patient is a lady who had recurrent tetany as the only manifestation of Gitelman's syndrome, which is an unusual presentation. Potassium replacement with supplementation of other deficient ions led to satisfactory clinical and biochemical response.

  12. Reversal of Thermoelectric Current in Tubular Nanowires

    NASA Astrophysics Data System (ADS)

    Erlingsson, Sigurdur I.; Manolescu, Andrei; Nemnes, George Alexandru; Bardarson, Jens H.; Sanchez, David

    2017-07-01

    We calculate the charge current generated by a temperature bias between the two ends of a tubular nanowire. We show that in the presence of a transversal magnetic field the current can change sign; i.e., electrons can either flow from the hot to the cold reservoir, or in the opposite direction, when the temperature bias increases. This behavior occurs when the magnetic field is sufficiently strong, such that Landau and snaking states are created, and the energy dispersion is nonmonotonic with respect to the longitudinal wave vector. The sign reversal can survive in the presence of impurities. We predict this result for core-shell nanowires, for uniform nanowires with surface states due to the Fermi level pinning, and for topological insulator nanowires.

  13. Tubular reabsorption in normal renal function.

    PubMed

    O'Connor, W J

    1984-01-01

    The purpose here is to examine in relation to normal renal function three factors which might affect tubular reabsorption: (1) The reabsorption of SO4, PO4, K, Cl, HCO3 and water are all linked to the reabsorption of Na. This would amount to the reabsorption by the tubules of a net reabsorbate of a composition similar to Locke's fluid. Fixed linkage of the reabsorption of a substance to the reabsorption of Na would be a very effective way of maintaining its plasma concentration within a narrow range. The substance would be retained unless its plasma concentration exceeds a threshold value and then small increase in plasma concentration determines its excretion. (2) The rate of reabsorption of Na and substances linked to it is increased when the volume of the intraluminal fluid is increased. This would explain why there is only a small increase in the excretion of Na and other electrolytes when glomerular filtration rate is increased after a meal of meat. (3) Plasma protein concentration affects tubular reabsorption. This would explain why fall in plasma protein is a main agent determining Na excretion in normal animals. Trying to see 'how far the observed facts can be brought into accord with a theory' reveals the difficulty of applying critical tests. On the one hand, the theories are not stated quantitatively in reference to the small changes of normal life; rather the evidence is from experiments with large changes. On the other hand, the small changes within the range of normal function, while themselves statistically significant, are too small for effective investigation of circumstances which may modify them. In the examples discussed here, we cannot say more than that the theories could explain the facts and their participation cannot be excluded.

  14. 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.

  15. Adsorption Isotherm Studies of CH4 on Tubular WS2

    NASA Astrophysics Data System (ADS)

    Mackie, Erica; Alkhafaji, Mazin; Migone, Aldo; Galvan, Donald

    1998-03-01

    We have measured adsorption-desorption isotherm cycles of CH4 on both tubular and non-tubular WS2. The tubular WS2 was produced (by Galvan et al.)(D.H.Galvan, R.Rangel and G.A.Nunez, submitted to Appl. Phys. Lett.) by electron irradiation of WS2 powder. The irradiation process results in WS2 tubes and paricles nanometric in diameter. The WS2 powder was manufactured by Alfa Aesar. We measured the surface area of both types of WS2 samples. We found an increase in surface area from 0.46 m^2/g for the non-irradiated, to 2.6 m^2/g for the irradiated WS2. We will present adsorption-desorption cycles for tubular and non-tubular WS2 subjected to different activation treatments: soaking in nitric acid, and, heating under vacuum to 700 C. Sufrace area comparisons between non-tubular and tubular, and between activated and non-activated WS2, will identify increases due to the potential opening of the tubes, the irradiation process itself, and/or the activation treatment.

  16. New dynamics in an old friend: dynamic tubular vacuoles radiate through the cortical cytoplasm of red onion epidermal cells.

    PubMed

    Wiltshire, Elizabeth J; Collings, David A

    2009-10-01

    The textbook image of the plant vacuole sitting passively in the centre of the cell is not always correct. We observed vacuole dynamics in the epidermal cells of red onion (Allium cepa) bulbs, using confocal microscopy to detect autofluorescence from the pigment anthocyanin. The central vacuole was penetrated by highly mobile transvacuolar strands of cytoplasm, which were also visible in concurrent transmitted light images. Tubular vacuoles also extended from the large central vacuole and radiated through the cortical cytoplasm. These tubules were thin, having a diameter of about 1.5 microm, and were connected to the central vacuole as shown by fluorescence recovery after photobleaching (FRAP) experiments. The tubules were bounded by the tonoplast, as revealed by transient expression of green fluorescent protein (GFP) targeted to the vacuolar membrane and through labeling with the dye MDY-64. Expression of endoplasmic reticulum-targeted GFP demonstrated that the vacuolar tubules were distinct from the cortical endoplasmic reticulum. Movement of the tubular vacuoles depended on actin microfilaments, as microfilament disruption blocked tubule movement and caused their collapse into minivacuoles. The close association of the tubules with GFP-tagged actin microfilaments suggests that the tubules are associated with myosin, and that tubules likely move along microfilaments. Tubular vacuoles do not require anthocyanin for their formation, as tubules were also present in white onion cells that lack anthocyanin. The function of these tubular vacuoles remains unknown, but as they greatly increase the surface area of the tonoplast, they might increase transport rates between the cytoplasm and vacuole.

  17. 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.

  18. AKI in early sepsis is a continuum from transient AKI without tubular damage over transient AKI with minor tubular damage to intrinsic AKI with severe tubular damage.

    PubMed

    Vanmassenhove, J; Glorieux, G; Hoste, E; Dhondt, A; Vanholder, R; Van Biesen, W

    2014-10-01

    The pathophysiology of septic acute kidney injury (AKI) is incompletely understood, and there is controversy on the role of renal hypoperfusion in early sepsis. We hypothesized that renal hypoperfusion plays a role in early sepsis and that there is a continuum between transient AKI without tubular damage, transient AKI with minor tubular damage, and intrinsic AKI. A total of 107 consecutive patients with sepsis were included. Fractional excretion of sodium (FENa), urinary, and serum neutrophil gelatinase-associated lipocalin were measured at admission (T0) and 4 h (T4) and 24 h later (T24). Patients were classified according to FENa quartiles (FENaQ). Transient and intrinsic AKI were respectively defined as AKI that did or did not recover to no AKI in the following 5 days. A total of 57 developed transient AKI, 22 developed intrinsic AKI, and 28 did not have AKI. Of the ten patients with transient AKI classified in the two lowest FENa quartiles (FENa < 0.36 %) and without signs of local tubular damage, seven still did not show signs of tubular damage 24 h later. Also, 50 % of patients with intrinsic AKI classified in the same FENaQ did not show signs of local tubular damage at admission but did so 24 h later. There is a continuum between transient AKI without tubular damage, transient AKI with minor tubular damage, and intrinsic AKI in sepsis. Renal hypoperfusion seems to be the instigator for the development of AKI in the majority of patients with early sepsis. Other mechanisms in some patients cannot be excluded.

  19. Tubular duplication of the oesophagus presenting with dysphagia.

    PubMed

    Saha, A K; Kundu, A K

    2014-06-01

    Duplications of the alimentary tract are rare congenital malformations, with the ileum being the most commonly affected site, followed by the oesophagus. Among oesophageal duplications, cystic duplication is the most common and the tubular variety, the rarest. Herein, we report a rare case of tubular oesophageal duplication, complicated by adenosquamous carcinoma at the lower end of the oesophagus, in a 32-year-old man who presented with progressive dysphagia. Although proton pump inhibitors may relieve dysphagia, oesophagectomy and gastric interpositioning should be the first-line treatment for patients with tubular oesophageal duplication, in order to reduce the risk of malignant transformation at the lower end of the oesophagus.

  20. Exceptional points in rolled-up tubular microcavities

    NASA Astrophysics Data System (ADS)

    Fang, Yangfu; Li, Shilong; Kiravittaya, Suwit; Mei, Yongfeng

    2017-09-01

    We observe the crossing and anti-crossing behaviors of nearly degenerate mode pairs in a rolled-up tubular microcavity, which can be explained by weak and strong couplings between the modes. Exceptional points (EPs) are thus obtained in the tubular microcavity since they are the critical point where a transition from strong to weak coupling occurs. Rolled-up tubular microcavities with a given resonant mode approaching an EP in parameter space expanded by two continuous variables are also realized without using near-field probes. Microcavities with EPs prepared in a rolled-up way could be mechanically stable and would be used for optofluidic detection.

  1. 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

  2. [Resistance analyses for recirculated membrane bioreactor].

    PubMed

    Yang, Qi; Huang, Xia; Shang, Hai-Tao; Wen, Xiang-Hua; Qian, Yi

    2006-11-01

    The resistance analyses for recirculated membrane bioreactor by the resistance-in-series model and the modified gel-polarization model respectively were extended to the turbulent ultrafiltration system. The experiments are carried out by dye wastewater in a tubular membrane module, it is found that the permeate fluxes are predicted very well by these models for turbinate systems. And the resistance caused by the concentration polarization is studied; the gel layer resistance is the most important of all the resistances.

  3. Tubular Peroxiredoxin 3 as a Predictor of Renal Recovery from Acute Tubular Necrosis in Patients with Chronic Kidney Disease

    PubMed Central

    Wu, Chia-Lin; Su, Tzu-Cheng; Chang, Chia-Chu; Kor, Chew-Teng; Chang, Chung-Ho; Yang, Tao-Hsiang; Chiu, Ping-Fang; Tarng, Der-Cherng

    2017-01-01

    Peroxiredoxin 3 (PRX3) is a mitochondrial antioxidant that regulates apoptosis in various cancers. However, whether tubular PRX3 predicts recovery of renal function following acute kidney injury (AKI) remains unknown. This retrospective cohort study included 54 hospitalized patients who had AKI with biopsy-proven acute tubular necrosis (ATN). The study endpoint was renal function recovery within 6 months. Of the 54 enrolled patients, 25 (46.3%) had pre-existing chronic kidney disease (CKD) and 33 (61%) recovered renal function. Tubular PRX3 expression was higher in patients with ATN than in those without renal function recovery. The level of tubular but not glomerular PRX3 expression predicted renal function recovery from AKI (AUROC = 0.76). In multivariate Cox regression analysis, high PRX3 expression was independently associated with a higher probability of renal function recovery (adjusted hazard ratio = 8.99; 95% CI 1.13–71.52, P = 0.04). Furthermore, the discriminative ability of the clinical model for AKI recovery was improved by adding tubular PRX3. High tubular PRX3 expression was associated with a higher probability of renal function recovery from ATN. Therefore, tubular PRX3 in combination with conventional predictors can further improve recovery prediction and may help with risk stratification in AKI patients with pre-existing CKD. PMID:28240739

  4. Tubular Peroxiredoxin 3 as a Predictor of Renal Recovery from Acute Tubular Necrosis in Patients with Chronic Kidney Disease.

    PubMed

    Wu, Chia-Lin; Su, Tzu-Cheng; Chang, Chia-Chu; Kor, Chew-Teng; Chang, Chung-Ho; Yang, Tao-Hsiang; Chiu, Ping-Fang; Tarng, Der-Cherng

    2017-02-27

    Peroxiredoxin 3 (PRX3) is a mitochondrial antioxidant that regulates apoptosis in various cancers. However, whether tubular PRX3 predicts recovery of renal function following acute kidney injury (AKI) remains unknown. This retrospective cohort study included 54 hospitalized patients who had AKI with biopsy-proven acute tubular necrosis (ATN). The study endpoint was renal function recovery within 6 months. Of the 54 enrolled patients, 25 (46.3%) had pre-existing chronic kidney disease (CKD) and 33 (61%) recovered renal function. Tubular PRX3 expression was higher in patients with ATN than in those without renal function recovery. The level of tubular but not glomerular PRX3 expression predicted renal function recovery from AKI (AUROC = 0.76). In multivariate Cox regression analysis, high PRX3 expression was independently associated with a higher probability of renal function recovery (adjusted hazard ratio = 8.99; 95% CI 1.13-71.52, P = 0.04). Furthermore, the discriminative ability of the clinical model for AKI recovery was improved by adding tubular PRX3. High tubular PRX3 expression was associated with a higher probability of renal function recovery from ATN. Therefore, tubular PRX3 in combination with conventional predictors can further improve recovery prediction and may help with risk stratification in AKI patients with pre-existing CKD.

  5. 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.

  6. Energy production with a tubular propeller turbine

    NASA Astrophysics Data System (ADS)

    Samora, I.; Hasmatuchi, V.; Münch-Alligné, C.; Franca, M. J.; Schleiss, A. J.; Ramos, H. M.

    2016-11-01

    Micro-hydropower is a way of improving the energetic efficiency of existent water systems. In the particular case of drinking water systems, several studies have showed that pressure reducing valves can be by-passed with turbines in order to recover the dissipated hydraulic energy to produce electricity. As conventional turbines are not always cost-effective for power under 20 kW, a new energy converter is studied. A five blade tubular propeller (5BTP), assessed through laboratorial tests on a reduced model with a diameter of 85 mm diameter and a maximal output power of 300 W, is addressed in this work. Having showed promising potential for further development, since global efficiencies of around 60% were observed, the turbine has been further used to estimate the potential for energy production in a real case study. A sub-grid of the drinking water system of the city of Lausanne, Switzerland, has been used to obtain an annual energy production through hourly simulations with several turbines.

  7. Status of tubular SOFC field unit demonstrations

    NASA Astrophysics Data System (ADS)

    George, Raymond A.

    Siemens Westinghouse is in the final stage of its tubular solid oxide fuel cell (SOFC) development program, and the program emphasis has shifted from basic technology development to cost reduction, scale-up and demonstration of pre-commercial power systems at customer sites. This paper describes our field unit demonstration program including the EDB/ELSAM 100-kW e combined heat and power (CHP) system, the Southern California Edison (SCE) 220-kW e pressurized SOFC/gas turbine (PSOFC/GT) power system, and the planned demonstrations of commercial prototype power systems. In the Spring of 1999, the EDB/ELSAM 100-kW e SOFC-CHP system produced 109 kW e net AC to the utility grid at 46% electrical efficiency and 65 kW t to the hot water district heating system, verifying the analytical predictions. The SCE 220-kW e PSOFC/GT power system will undergo factory startup in the Fall of 1999.

  8. 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.

  9. Tubular Heart Valves from Decellularized Engineered Tissue

    PubMed Central

    Syedain, Zeeshan H.; Meier, Lee A.; Reimer, Jay; Tranquillo, Robert T.

    2013-01-01

    A novel tissue-engineered heart valve (TEHV) was fabricated from a decellularized tissue tube mounted on a frame with three struts, which upon back-pressure cause the tube to collapse into three coapting “leaflets”. The tissue was completely biological, fabricated from ovine fibroblasts dispersed within a fibrin gel, compacted into a circumferentially-aligned tube on a mandrel, and matured using a bioreactor system that applied cyclic distension. Following decellularization, the resulting tissue possessed tensile mechanical properties, mechanical anisotropy, and collagen content that were comparable to native pulmonary valve leaflets. When mounted on a custom frame and tested within a pulse duplicator system, the tubular TEHV displayed excellent function under both aortic and pulmonary conditions, with minimal regurgitant fractions and transvalvular pressure gradients at peak systole, as well as well as effective orifice areas exceeding those of current commercially available valve replacements. Short-term fatigue tests of one million cycles with pulmonary pressure gradients was conducted without significant change in mechanical properties and no observable macroscopic tissue deterioration. This study presents an attractive potential alternative to current tissue valve replacements due to its avoidance of chemical fixation and utilization of a tissue conducive to recellularization by host cell infiltration. PMID:23897047

  10. 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

  11. 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.

  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. Genetics Home Reference: renal tubular acidosis with deafness

    MedlinePlus

    ... to softening and weakening of the bones , called rickets in children and osteomalacia in adults. This bone ... tubular acidosis and sensorineural hearing loss. Clin Genet. 2013 Mar;83(3):274-8. doi: 10.1111/ ...

  14. 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)

  15. 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)

  16. Membranes: role in synfuels plants

    SciTech Connect

    Not Available

    1984-05-28

    A news item reports that reverse osmosis is to be used in a demonstration project for recycling waste water from a coal processing plant. Bend Research Inc. have a US Department of Energy contract to build a plant to treat about 2000 gal/day. They will use polysulphone, hollow-fibre reverse-osmosis membrane packed into 10 tubular modules, each having some 25 ft/SUP/2 of membrane surface area. The objective is the development of a suitable water-recycling system for synthetic fuels plants, which typically use very large quantities of water and are located in areas of water scarcity.

  17. Mechanisms of renal tubular defects in old age.

    PubMed Central

    Dontas, A. S.; Marketos, S. G.; Papanayiotou, P.

    1972-01-01

    The mechanisms of renal tubular dysfunction in old age have been examined in twenty-eight clinically healthy elderly subjects without infection, and in fourteen subjects of similar age with laboratory evidence of intrarenal infection. The data were compared with those from thirteen clinically healthy young subjects. Studied were: proximal tubular (Tm(PAH)) and distal tubular (CH2O) activity, minimal and maximal osmolal U/P ratios, maximal osmolal excretion in hydropenia, and GFR levels under standard hydration and under water-loading. The reduction of GFR in old age is evident particularly in men under conditions of standard hydration: it is accentuated in the presence of renal infection. Proximal tubular activity is also significantly lower in elderly men, especially if they have chronic bacteriuria. The reduction is closely related to GFR levels, with identical Tm(PAH):C(in) ratios in all groups. This supports the intact nephron hypothesis for this part of the nephron. Distal tubular activity is depressed in old age in both sexes proportionately more than proximal tubular activity or the GFR. The lower CH2O: GFR ratios imply a selective distal tubular damage. Maximal osmolal U/P ratios in hydropenia are significantly higher in the young (mean 367) than in either the elderly non-infected (mean 279) or the elderly infected subjects (mean 212). Conversely, minimal U/P ratios in water-loading are lower in the young (mean 0.247) than in either elderly group (means 0.418 and 0.668). Osmolal excretion in hydropenia is not different between the groups, but urine flows in water-loading clearly separate them. The data indicate that simple functions of the distal-collecting tubule (e.g. the CH2O), are less affected in old age than are functions involving several medullary structures (as is the maximal U(osm) or U/P ratio). They suggest that the main impairment of the distal tubular cell involves the failure to achieve a proper osmotic gradient between tubular fluid and

  18. Transient Distal Renal Tubular Acidosis in Organophosphate Poisoning

    PubMed Central

    Narayan, Ram; Abdulla, Mansoor C.; Alungal, Jemshad

    2017-01-01

    Renal complications due to organophosphate poisoning are very rare. We are presenting a unique case of transient distal renal tubular acidosis due to organophosphate poisoning, which to the best of our knowledge is the first of its kind. An elderly female after deliberate self-harm with ingestion of chlorpyrifos had multiple ventricular arrhythmias due to hypokalemia secondary to distal renal tubular acidosis which improved completely after treatment.

  19. Worse Prognosis in Papillary, Compared to Tubular, Early Gastric Carcinoma

    PubMed Central

    Yu, Huiping; Fang, Cheng; Chen, Lin; Shi, Jiong; Fan, Xianshan; Zou, Xiaoping; Huang, Qin

    2017-01-01

    Purpose: Papillary early gastric carcinoma (EGC) is uncommon but shows worse prognosis in our most recent study in a Chinese population with unknown reasons. The aim of the present study was to further investigate risk factors for worse prognosis in patients with papillary adenocarcinoma, compared to those with tubular adenocarcinoma. Methods: We searched the electronic pathology databank for radical gastrectomy cases over an 8-year period at a single medical center in Nanjing, China, and identified consecutive 240 EGC cases that were classified as either papillary (n=59) or tubular (n=181) EGC tumors in accordance with the World Health Organization (WHO) gastric cancer diagnosis criteria. We investigated and compared clinicopathologic risk factors for prognosis between papillary and tubular EGC groups. All patients were followed up and their 5-year survival rate was compared statistically with the Kaplan-Meier method with a log rank test. Results: Compared to tubular EGCs, papillary EGCs were significantly more common in elderly patients, more frequently occurred in the proximal stomach with protruding/elevated growth patterns, submucosal invasion, and a micropapillary component. Although lymphovascular invasion (16.9%), nodal (13.6%) and distant (11.8%) metastases in papillary EGCs were more frequent than those (8.3%, 7.2%, and 3.7%, respectively) in tubular EGCs, the differences approached but did not reach statistically significant levels. Significant risk factors for nodal metastasis included lymphovascular invasion in both EGC groups, but the ulcerative pattern and submucosal invasion only in tubular EGCs. The 5-year survival rate was significantly worse in papillary (80.5%) than in tubular (96.8%) EGCs. Conclusions: Compared to tubular EGCs, papillary EGCs diagnosed with the WHO criteria in Chinese patients were more frequent in elderly patients, proximal stomach and showed the significantly worse 5-year survival rate with more protruding/elevated growth

  20. Tubular Epithelial NF-κB Activity Regulates Ischemic AKI.

    PubMed

    Markó, Lajos; Vigolo, Emilia; Hinze, Christian; Park, Joon-Keun; Roël, Giulietta; Balogh, András; Choi, Mira; Wübken, Anne; Cording, Jimmi; Blasig, Ingolf E; Luft, Friedrich C; Scheidereit, Claus; Schmidt-Ott, Kai M; Schmidt-Ullrich, Ruth; Müller, Dominik N

    2016-09-01

    NF-κB is a key regulator of innate and adaptive immunity and is implicated in the pathogenesis of AKI. The cell type-specific functions of NF-κB in the kidney are unknown; however, the pathway serves distinct functions in immune and tissue parenchymal cells. We analyzed tubular epithelial-specific NF-κB signaling in a mouse model of ischemia-reperfusion injury (IRI)-induced AKI. NF-κB reporter activity and nuclear localization of phosphorylated NF-κB subunit p65 analyses in mice revealed that IRI induced widespread NF-κB activation in renal tubular epithelia and in interstitial cells that peaked 2-3 days after injury. To genetically antagonize tubular epithelial NF-κB activity, we generated mice expressing the human NF-κB super-repressor IκBαΔN in renal proximal, distal, and collecting duct epithelial cells. Compared with control mice, these mice exhibited improved renal function, reduced tubular apoptosis, and attenuated neutrophil and macrophage infiltration after IRI-induced AKI. Furthermore, tubular NF-κB-dependent gene expression profiles revealed temporally distinct functional gene clusters for apoptosis, chemotaxis, and morphogenesis. Primary proximal tubular cells isolated from IκBαΔN-expressing mice and exposed to hypoxia-mimetic agent cobalt chloride exhibited less apoptosis and expressed lower levels of chemokines than cells from control mice did. Our results indicate that postischemic NF-κB activation in renal tubular epithelia aggravates tubular injury and exacerbates a maladaptive inflammatory response.

  1. Estimation of the bending rigidity and spontaneous curvature of fluid membranes in simulations.

    PubMed

    Shiba, Hayato; Noguchi, Hiroshi

    2011-09-01

    Several numerical methods for measuring the bending rigidity and the spontaneous curvature of fluid membranes are studied using two types of meshless membrane models. The bending rigidity is estimated from the thermal undulations of planar and tubular membranes and the axial force of tubular membranes. We found a large dependence of its estimate value from the thermal undulation analysis on the upper-cutoff frequency q(cut) of the least-squares fit. The inverse power-spectrum fit with an extrapolation to q(cut)→0 yields the smallest estimation error among the investigated methods. The spontaneous curvature is estimated from the axial force of tubular membranes and the average curvature of bent membrane strips. The results of these methods show good agreement with each other.

  2. Irritable bowel syndrome in women undergoing hysterectomy and tubular ligation

    PubMed Central

    Khoshbaten, Manouchehr; Melli, Manigheh Syah; Fattahi, Monireh Jabar; Sharifi, Nasrin; Mostafavi, Seyed Abolfazl

    2011-01-01

    Aim The aim of this study was to assess the incidence of irritable bowel syndrome in women undergoing hysterectomy and tubular ligation. Background The results of previous studies have shown an increased incidence of irritable bowel syndrome after gynecological surgeries. Patients and methods Participants were patients of Alzahra and Taleghani University hospitals in Tabriz. One hundred and seventy two women without gastrointestinal symptoms or a diagnosis of the irritable bowel syndrome underwent tubular ligation and 164 women underwent hysterectomy. Patients were assessed every 3 month after hysterectomy and tubular ligation for 12 months. Irritable bowel syndrome was diagnosed by a questionnaire based on Rome II criteria. Results During 12 months after surgeries, 19 (11%) patients in tubular ligation group and 19 (11%) in hysterectomy group had abdominal pain with at least two symptoms of irritable bowel syndrome. Irritable bowel syndrome was diagnosed in 9 (5%) patients in the tubular ligation and 13 (8%) patients in hysterectomy groups (P>0.05). In both studied groups, the most prevalent symptoms along with abdominal pain were chronic constipation and abnormal bowel movement and the least prevalent were diarrhea and passage of mucus. Conclusion These results suggest that gynecological surgeries (tubular ligation and hysterectomy) may predispose to the development of the irritable bowel syndrome. PMID:24834172

  3. A cut-off tubular geometry of loop space

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Partha

    Motivated by the computation of loop space quantum mechanics as indicated in [14], here we seek a better understanding of the tubular geometry of loop space ℒℳ corresponding to a Riemannian manifold ℳ around the submanifold of vanishing loops. Our approach is to first compute the tubular metric of (ℳ2N+1) C around the diagonal submanifold, where (ℳN) C is the Cartesian product of N copies of ℳ with a cyclic ordering. This gives an infinite sequence of tubular metrics such that the one relevant to ℒℳ can be obtained by taking the limit N →∞. Such metrics are computed by adopting an indirect method where the general tubular expansion theorem of [21] is crucially used. We discuss how the complete reparametrization isometry of loop space arises in the large-N limit and verify that the corresponding Killing equation is satisfied to all orders in tubular expansion. These tubular metrics can alternatively be interpreted as some natural Riemannian metrics on certain bundles of tangent spaces of ℳ which, for ℳ×ℳ, is the tangent bundle Tℳ.

  4. 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.

  5. [Neonatal hypoxic-ischemic nephropathy and urinary diagnostic indices: the utility of measuring tubular enzymes (NAG and AAP)].

    PubMed

    Bertotti, A; De Marchi, S; Brovedani, P; Gaeta, G; Peratoner, L; Mangiarotti, M A

    1990-01-01

    Feto-neonatal hypoxia can cause a functional kidney impairment, which is often temporary and not clinically overt, but sometimes leading to acute renal failure. Hypoxic stress may result in a tubulo-interstitial damage, and kidney tubular enzymes determination has proved to be an easy, early, and non invasive method to define a tubular interstitial lesion. A major target of nephrotoxicity is the proximal tubular cell: alterations in brush-border membrane and cytoplasm result in increased turnover processes in the kidney cortex, following by a corresponding increased excretion of alanine-aminopeptidase (AAP) and N-acetyl-glucosaminidase (NAG) from the proximal tubular cells, long before glomerular or tubular functions are impaired. AAP and NAG excretion is directly correlated with the strength and the duration of toxic alteration of the proximal tubule. NAG and AAP have been already studied in the adults and the children; they have been chosen for this investigation with a double aim: 1) to define the amount of their urinary excretion in relation with gestational age at birth; 2) to evaluate if in the newborn, independently of the gestational age, their urinary concentration may be increased by ischaemic conditions caused by hypoxia. We studied 52 healthy newborns (7 preterm of 33-36 weeks and 45 full-term) and 16 newborns with feto-neonatal hypoxia (8 preterm of 26-36 weeks and full-term) at the forth day of life. Urinary NAG and AAP were assayed by colorimetric methods and the results expressed as mU/mg. creatininuria.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Factors affecting proximal tubular reabsorption during development

    SciTech Connect

    Kaskel, F.J.; Kumar, A.M.; Lockhart, E.A.; Evan, A.; Spitzer, A.

    1987-01-01

    Studies performed in several animal species have demonstrated that glomerulotubular balance is maintained throughout development despite the many changes that occur in the factors known to control it. In an attempt to understand the nature of this phenomenon the authors quantified the magnitude and described the profile of these changes in guinea pigs. The changes in physical forces were assessed from measurements of hydrostatic and oncotic pressures, whereas those in the permeability characteristics of the proximal tubule epithelium were estimated from permanence to radioactivity-labelled macromolecules of graded radii, histologic measurements of the intercellular channels, and measurements of end-proximal ratio of tubular fluid-to-plasma osmolality (TF/P/sub osm/). Between 1 and 50 days of age the net pressure for reabsorption increased from 15.0 to 30.9 mmHg with the major change occurring during the first 2-3 wk of postnatal life. The urinary recovery of (/sup 3/H)inulin, (/sup 14/C)sucrose, and (/sup 14/C)creatinine, injected in the early segment of proximal tubules did not vary with age. The urinary recovery of (/sup 14/C)mannitol increased from 92% at birth to 100% at 49 days of age. The length of the zonulae occludens and the width of the intercellular channels did not change during this period. The findings support the hypothesis that during early postnatal life glomerulotubular balance is made possible by a high permeability of the proximal tubule, which compensates for the low net reabsorptive pressure. As the animal matures and the proximal tubule epithelium becomes tighter, for glomerulotubular balance to be maintained, an increase in the number of intercellular channels and in the active transport of sodium need to be postulated.

  7. 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

    2011-08-02

    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.

  8. Mobility in geometrically confined membranes

    PubMed Central

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

    2011-01-01

    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

  9. Membrane-mediated aggregation of curvature-inducing nematogens and membrane tubulation.

    PubMed

    Ramakrishnan, N; Sunil Kumar, P B; Ipsen, John H

    2013-03-05

    The shapes of cell membranes are largely regulated by membrane-associated, curvature-active proteins. Herein, we use a numerical model of the membrane, recently developed by us, with elongated membrane inclusions possessing spontaneous directional curvatures that could be different along, and perpendicular to, the membrane's long axis. We show that, due to membrane-mediated interactions, these curvature-inducing membrane-nematogens can aggregate spontaneously, even at low concentrations, and change the local shape of the membrane. We demonstrate that for a large group of such inclusions, where the two spontaneous curvatures have equal sign, the tubular conformation and sometimes the sheet conformation of the membrane are the common equilibrium shapes. We elucidate the factors necessary for the formation of these protein lattices. Furthermore, the elastic properties of the tubes, such as their compressional stiffness and persistence length, are calculated. Finally, we discuss the possible role of nematic disclination in capping and branching of the tubular membranes. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Reorganization of the Endosomal System in Salmonella-Infected Cells: The Ultrastructure of Salmonella-Induced Tubular Compartments

    PubMed Central

    Krieger, Viktoria; Liebl, David; Zhang, Yuying; Rajashekar, Roopa; Chlanda, Petr; Giesker, Katrin; Chikkaballi, Deepak; Hensel, Michael

    2014-01-01

    During the intracellular life of Salmonella enterica, a unique membrane-bound compartment termed Salmonella-containing vacuole, or SCV, is formed. By means of translocated effector proteins, intracellular Salmonella also induce the formation of extensive, highly dynamic membrane tubules termed Salmonella-induced filaments or SIF. Here we report the first detailed ultrastructural analyses of the SCV and SIF by electron microscopy (EM), EM tomography and live cell correlative light and electron microscopy (CLEM). We found that a subset of SIF is composed of double membranes that enclose portions of host cell cytosol and cytoskeletal filaments within its inner lumen. Despite some morphological similarities, we found that the formation of SIF double membranes is independent from autophagy and requires the function of the effector proteins SseF and SseG. The lumen of SIF network is accessible to various types of endocytosed material and our CLEM analysis of double membrane SIF demonstrated that fluid phase markers accumulate only between the inner and outer membrane of these structures, a space continual with endosomal lumen. Our work reveals how manipulation of the endosomal membrane system by an intracellular pathogen results in a unique tubular membrane compartmentalization of the host cell, generating a shielded niche permissive for intracellular proliferation of Salmonella. PMID:25254663

  11. Autophagy protects renal tubular cells against cyclosporine toxicity.

    PubMed

    Pallet, Nicolas; Bouvier, Nicolas; Legendre, Christophe; Gilleron, Jerome; Codogno, Patrice; Beaune, Philippe; Thervet, Eric; Anglicheau, Dany

    2008-08-01

    A major side effect of the powerful immunosuppressive drug cyclosporine (CsA) is the development of a chronic nephrotoxicity whose mechanisms are not fully understood. Recent data suggest that tubular cells play a central role in the pathogenesis of chronic nephropathies. We have shown that CsA is responsible for endoplasmic reticulum (ER) stress in tubular cells. Autophagy has recently been described to be induced by ER stress and to alleviate its deleterious effects. In this study, we demonstrate that CsA induces autophagy in primary cultured human renal tubular cells through LC3II expression and autophagosomes visualization by electron microscopy. Autophagy is dependant on ER stress because various ER stress inducers activate autophagy, and salubrinal, an inhibitor of eIF2alpha dephosphorylation that protects cells against ER stress, inhibited LC3II expression. Furthermore, autophagy inhibition during CsA treatment with beclin1 siRNA significantly increases tubular cell death. Finally, immunohistochemical analysis of rat kidneys demonstrates a positive LC3 staining on injured tubular cells, suggesting that CsA induces autophagy in vivo. Taken together, these results demonstrate that CsA, through ER stress induction, activates autophagy as a protection against cell death.

  12. Tubular cell apoptosis and cidofovir-induced acute renal failure.

    PubMed

    Ortiz, Alberto; Justo, Pilar; Sanz, Ana; Melero, Rosa; Caramelo, Carlos; Guerrero, Manuel Fernández; Strutz, Frank; Müller, Gerhard; Barat, Antonio; Egido, Jesus

    2005-01-01

    Cidofovir is an antiviral drug with activity against a wide array of DNA viruses including poxvirus. The therapeutic use of cidofovir is marred by a dose-limiting side effect, nephrotoxicity, leading to proximal tubular cell injury and acute renal failure. Treatment with cidofovir requires the routine use of prophylactic measures. A correct knowledge of the cellular and molecular mechanisms of cidofovir toxicity may lead to the development of alternative prophylactic strategies. We recently cared for a patient with irreversible acute renal failure due to cidofovir. Renal biopsy showed tubular cell apoptosis. Cidofovir induced apoptosis in primary cultures of human proximal tubular cells in a temporal (peak apoptosis at 7 days) and concentration (10-40 microg/ml) pattern consistent with that of clinical toxicity. Apoptosis was identified by the presence of hypodiploid cells, by the exposure of annexin V binding sites and by morphological features and was associated with the appearance of active caspase-3 fragments. Cell death was specific as it was also present in a human proximal tubular epithelial cell line (HK-2), but not in a human kidney fibroblast cell line, and was prevented by probenecid. An inhibitor of caspase-3 (DEVD) prevented cidofovir apoptosis. The survival factors present in serum, insulin-like growth factor-1 and hepatocyte growth factor, were also protective. The present data suggest that apoptosis induction is a mechanism contributing to cidofovir nephrotoxicity. The prophylactic administration of factors with survival activity for tubular epithelium should be further explored in cidofovir renal injury.

  13. Macrophage Stimulating Protein May Promote Tubular Regeneration after Acute Injury

    PubMed Central

    Cantaluppi, Vincenzo; Biancone, Luigi; Romanazzi, Giuseppe Mauriello; Figliolini, Federico; Beltramo, Silvia; Galimi, Francesco; Camboni, Maria Gavina; Deriu, Elisa; Conaldi, Piergiulio; Bottelli, Antonella; Orlandi, Viviana; Herrera, Maria Beatriz; Pacitti, Alfonso; Segoloni, Giuseppe Paolo; Camussi, Giovanni

    2008-01-01

    Macrophage-stimulating protein (MSP) exerts proliferative and antiapoptotic effects, suggesting that it may play a role in tubular regeneration after acute kidney injury. In this study, elevated plasma levels of MSP were found both in critically ill patients with acute renal failure and in recipients of renal allografts during the first week after transplantation. In addition, MSP and its receptor, RON, were markedly upregulated in the regenerative phase after glycerol-induced tubular injury in mice. In vitro, MSP stimulated tubular epithelial cell proliferation and conferred resistance to cisplatin-induced apoptosis by inhibiting caspase activation and modulating Fas, mitochondrial proteins, Akt, and extracellular signal–regulated kinase. MSP also enhanced migration, scattering, branching morphogenesis, tubulogenesis, and mesenchymal de-differentiation of surviving tubular cells. In addition, MSP induced an embryonic phenotype characterized by Pax-2 expression. In conclusion, MSP is upregulated during the regeneration of injured tubular cells, and it exerts multiple biologic effects that may aid recovery from acute kidney injury. PMID:18614774

  14. Autophagy Induces Prosenescent Changes in Proximal Tubular S3 Segments

    PubMed Central

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

    2016-01-01

    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 (Atg5Δflox/Δflox) 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, Atg5Δflox/Δflox 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

  15. Generation of kidney tubular organoids from human pluripotent stem cells

    PubMed Central

    Yamaguchi, Shintaro; Morizane, Ryuji; Homma, Koichiro; Monkawa, Toshiaki; Suzuki, Sayuri; Fujii, Shizuka; Koda, Muneaki; Hiratsuka, Ken; Yamashita, Maho; Yoshida, Tadashi; Wakino, Shu; Hayashi, Koichi; Sasaki, Junichi; Hori, Shingo; Itoh, Hiroshi

    2016-01-01

    Recent advances in stem cell research have resulted in methods to generate kidney organoids from human pluripotent stem cells (hPSCs), which contain cells of multiple lineages including nephron epithelial cells. Methods to purify specific types of cells from differentiated hPSCs, however, have not been established well. For bioengineering, cell transplantation, and disease modeling, it would be useful to establish those methods to obtain pure populations of specific types of kidney cells. Here, we report a simple two-step differentiation protocol to generate kidney tubular organoids from hPSCs with direct purification of KSP (kidney specific protein)-positive cells using anti-KSP antibody. We first differentiated hPSCs into mesoderm cells using a glycogen synthase kinase-3β inhibitor for 3 days, then cultured cells in renal epithelial growth medium to induce KSP+ cells. We purified KSP+ cells using flow cytometry with anti-KSP antibody, which exhibited characteristics of all segments of kidney tubular cells and cultured KSP+ cells in 3D Matrigel, which formed tubular organoids in vitro. The formation of tubular organoids by KSP+ cells induced the acquisition of functional kidney tubules. KSP+ cells also allowed for the generation of chimeric kidney cultures in which human cells self-assembled into 3D tubular structures in combination with mouse embryonic kidney cells. PMID:27982115

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

    PubMed

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

    2017-01-09

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

  17. Constitutive Activation of the Calcium Sensor STIM1 Causes Tubular-Aggregate Myopathy

    PubMed Central

    Böhm, Johann; Chevessier, Frédéric; De Paula, André Maues; Koch, Catherine; Attarian, Shahram; Feger, Claire; Hantaï, Daniel; Laforêt, Pascal; Ghorab, Karima; Vallat, Jean-Michel; Fardeau, Michel; Figarella-Branger, Dominique; Pouget, Jean; Romero, Norma B.; Koch, Marc; Ebel, Claudine; Levy, Nicolas; Krahn, Martin; Eymard, Bruno; Bartoli, Marc; Laporte, Jocelyn

    2013-01-01

    Tubular aggregates are regular arrays of membrane tubules accumulating in muscle with age. They are found as secondary features in several muscle disorders, including alcohol- and drug-induced myopathies, exercise-induced cramps, and inherited myasthenia, but also exist as a pure genetic form characterized by slowly progressive muscle weakness. We identified dominant STIM1 mutations as a genetic cause of tubular-aggregate myopathy (TAM). Stromal interaction molecule 1 (STIM1) is the main Ca2+ sensor in the endoplasmic reticulum, and all mutations were found in the highly conserved intraluminal Ca2+-binding EF hands. Ca2+ stores are refilled through a process called store-operated Ca2+ entry (SOCE). Upon Ca2+-store depletion, wild-type STIM1 oligomerizes and thereby triggers extracellular Ca2+ entry. In contrast, the missense mutations found in our four TAM-affected families induced constitutive STIM1 clustering, indicating that Ca2+ sensing was impaired. By monitoring the calcium response of TAM myoblasts to SOCE, we found a significantly higher basal Ca2+ level in TAM cells and a dysregulation of intracellular Ca2+ homeostasis. Because recessive STIM1 loss-of-function mutations were associated with immunodeficiency, we conclude that the tissue-specific impact of STIM1 loss or constitutive activation is different and that a tight regulation of STIM1-dependent SOCE is fundamental for normal skeletal-muscle structure and function. PMID:23332920

  18. Urinary Exosomes Contain MicroRNAs Capable of Paracrine Modulation of Tubular Transporters in Kidney

    PubMed Central

    Gracia, Tannia; Wang, Xiaonan; Su, Ya; Norgett, Elizabeth E.; Williams, Timothy L.; Moreno, Pablo; Micklem, Gos; Frankl, Fiona E. Karet

    2017-01-01

    Exosomes derived from all nephron segments are present in human urine, where their functionality is incompletely understood. Most studies have focused on biomarker discovery rather than exosome function. Through sequencing we identified the miRNA repertoire of urinary exosomes from healthy volunteers; 276 mature miRNAs and 345 pre-miRNAs were identified (43%/7% of reads). Among the most abundant were members of the miR-10, miR-30 and let-7 families. Targets for the identified miRNAs were predicted using five different databases; genes encoding membrane transporters and their regulators were enriched, highlighting the possibility that these miRNAs could modulate key renal tubular functions in a paracrine manner. As proof of concept, cultured renal epithelial cells were exposed to urinary exosomes and cellular exosomal uptake was confirmed; thereafter, reduced levels of the potassium channel ROMK and kinases SGK1 and WNK1 were observed in a human collecting duct cell line, while SPAK was unaltered. In proximal tubular cells, mRNA levels of the amino acid transporter gene SLC38A2 were diminished and reflected in a significant decrement of its encoded protein SNAT2. Protein levels of the kinase SGK1 did not change. Thus we demonstrated a novel potential function for miRNA in urinary exosomes. PMID:28094285

  19. Engineered extracellular matrices with controlled mechanics modulate renal proximal tubular cell epithelialization

    PubMed Central

    Chen, Evan; Putnam, Andrew J.

    2017-01-01

    Acute kidney injury (AKI) is common and associated with significant morbidity and mortality. Recovery from many forms of AKI involves the proliferation of renal proximal tubular epithelial cells (RPTECs), but the influence of the microenvironment in which this recovery occurs remains poorly understood. Here we report the development of a poly(ethylene glycol) (PEG) hydrogel platform to study the influence of substrate mechanical properties on the proliferation of human RPTECs as a model for recovery from AKI. PEG diacrylate based hydrogels were generated with orthogonal control of mechanics and cell-substrate interactions. Using this platform, we found that increased substrate stiffness promotes RPTEC spreading and proliferation. RPTECs showed similar degrees of apoptosis and Yes-associated protein (YAP) nuclear localization regardless of stiffness, suggesting these were not key mediators of the effect. However, focal adhesion formation, cytoskeletal organization, focal adhesion kinase (FAK) activation, and extracellular signal-regulated kinase (ERK) activation were all enhanced with increasing substrate stiffness. Inhibition of ERK activation substantially attenuated the effect of stiffness on proliferation. In long-term culture, hydrogel stiffness promoted the formation of more complete epithelial monolayers with tight junctions, cell polarity, and an organized basement membrane. These data suggest that increased stiffness potentially may have beneficial consequences for the renal tubular epithelium during recovery from AKI. PMID:28715434

  20. Engineered extracellular matrices with controlled mechanics modulate renal proximal tubular cell epithelialization.

    PubMed

    Beamish, Jeffrey A; Chen, Evan; Putnam, Andrew J

    2017-01-01

    Acute kidney injury (AKI) is common and associated with significant morbidity and mortality. Recovery from many forms of AKI involves the proliferation of renal proximal tubular epithelial cells (RPTECs), but the influence of the microenvironment in which this recovery occurs remains poorly understood. Here we report the development of a poly(ethylene glycol) (PEG) hydrogel platform to study the influence of substrate mechanical properties on the proliferation of human RPTECs as a model for recovery from AKI. PEG diacrylate based hydrogels were generated with orthogonal control of mechanics and cell-substrate interactions. Using this platform, we found that increased substrate stiffness promotes RPTEC spreading and proliferation. RPTECs showed similar degrees of apoptosis and Yes-associated protein (YAP) nuclear localization regardless of stiffness, suggesting these were not key mediators of the effect. However, focal adhesion formation, cytoskeletal organization, focal adhesion kinase (FAK) activation, and extracellular signal-regulated kinase (ERK) activation were all enhanced with increasing substrate stiffness. Inhibition of ERK activation substantially attenuated the effect of stiffness on proliferation. In long-term culture, hydrogel stiffness promoted the formation of more complete epithelial monolayers with tight junctions, cell polarity, and an organized basement membrane. These data suggest that increased stiffness potentially may have beneficial consequences for the renal tubular epithelium during recovery from AKI.

  1. 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}.

  2. 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.

  3. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    DOE PAGES

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; ...

    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

  4. 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

  5. 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.

  6. Open-closed switching of synthetic tubular pores

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  7. Numerical study of cavitation flows inside a tubular pumping station

    NASA Astrophysics Data System (ADS)

    Tang, X. L.; Huang, W.; Wang, F. J.; Yang, W.; Wu, Y. L.

    2012-11-01

    Based on RNG k-epsilon turbulence model and the full cavitation model, the cavitation flows inside a low-head tubular-pump model were predicted by using the FLUENT software. For a operating case of given flow rate, cavitation happens near the inlet on the suction surfaces of the impeller blades at the initial cavitating stage, and the cavitating area spreads to the impeller passage and hub as NPSH (net positive suction head) decreases, which will affect energy transformation. For various operating cases of cavitation flows at the given flow rates, the predicted velocity and pressure distributions as well as the vapor volumetric fraction are systematically analyzed. Finally, the cavitation performance curve of the tubular-pump model is obtained by means of the further post-processing. All the comparisons and analysis can be further employed to optimize the hydraulic and structural design of the tubular pump and to guide its safe operation.

  8. Rap1 Ameliorates Renal Tubular Injury in Diabetic Nephropathy

    PubMed Central

    Xiao, Li; Zhu, Xuejing; Yang, Shikun; Liu, Fuyou; Zhou, Zhiguang; Zhan, Ming; Xie, Ping; Zhang, Dongshan; Li, Jun; Song, Panai; Kanwar, Yashpal S.; Sun, Lin

    2014-01-01

    Rap1b ameliorates high glucose (HG)-induced mitochondrial dysfunction in tubular cells. However, its role and precise mechanism in diabetic nephropathy (DN) in vivo remain unclear. We hypothesize that Rap1 plays a protective role in tubular damage of DN by modulating primarily the mitochondria-derived oxidative stress. The role and precise mechanisms of Rap1b on mitochondrial dysfunction and of tubular cells in DN were examined in rats with streptozotocin (STZ)-induced diabetes that have Rap1b gene transfer using an ultrasound microbubble-mediated technique as well as in renal proximal epithelial tubular cell line (HK-2) exposed to HG ambiance. The results showed that Rap1b expression decreased significantly in tubules of renal biopsies from patients with DN. Overexpression of a constitutively active Rap1b G12V notably ameliorated renal tubular mitochondrial dysfunction, oxidative stress, and apoptosis in the kidneys of STZ-induced rats, which was accompanied with increased expression of transcription factor C/EBP-β and PGC-1α. Furthermore, Rap1b G12V also decreased phosphorylation of Drp-1, a key mitochondrial fission protein, while boosting the expression of genes related to mitochondrial biogenesis and antioxidants in HK-2 cells induced by HG. These effects were imitated by transfection with C/EBP-β or PGC-1α short interfering RNA. In addition, Rap1b could modulate C/EBP-β binding to the endogenous PGC-1α promoter and the interaction between PGC-1α and catalase or mitochondrial superoxide dismutase, indicating that Rap1b ameliorates tubular injury and slows the progression of DN by modulation of mitochondrial dysfunction via C/EBP-β–PGC-1α signaling. PMID:24353183

  9. Tubular collagen scaffolds with radial elasticity for hollow organ regeneration.

    PubMed

    Versteegden, Luuk R; van Kampen, Kenny A; Janke, Heinz P; Tiemessen, Dorien M; Hoogenkamp, Henk R; Hafmans, Theo G; Roozen, Edwin A; Lomme, Roger M; van Goor, Harry; Oosterwijk, Egbert; Feitz, Wout F; van Kuppevelt, Toin H; Daamen, Willeke F

    2017-04-01

    Tubular collagen scaffolds have been used for the repair of damaged hollow organs in regenerative medicine, but they generally lack the ability to reversibly expand in radial direction, a physiological characteristic seen in many native tubular organs. In this study, tubular collagen scaffolds were prepared that display a shape recovery effect and therefore exhibit radial elasticity. Scaffolds were constructed by compression of fibrillar collagen around a star-shaped mandrel, mimicking folds in a lumen, a typical characteristic of empty tubular hollow organs, such as ureter or urethra. Shape recovery effect was introduced by in situ fixation using a star-shaped mandrel, 3D-printed clamps and cytocompatible carbodiimide crosslinking. Prepared scaffolds expanded upon increase of luminal pressure and closed to the star-shaped conformation after removal of pressure. In this study, we applied this method to construct a scaffold mimicking the dynamics of human urethra. Radial expansion and closure of the scaffold could be iteratively performed for at least 1000 cycles, burst pressure being 132±22mmHg. Scaffolds were seeded with human epithelial cells and cultured in a bioreactor under dynamic conditions mimicking urination (pulse flow of 21s every 2h). Cells adhered and formed a closed luminal layer that resisted flow conditions. In conclusion, a new type of a tubular collagen scaffold has been constructed with radial elastic-like characteristics based on the shape of the scaffold, and enabling the scaffold to reversibly expand upon increase in luminal pressure. These scaffolds may be useful for regenerative medicine of tubular organs.

  10. Facile fabrication of nanofluidic diode membranes using anodic aluminium oxide

    NASA Astrophysics Data System (ADS)

    Wu, Songmei; Wildhaber, Fabien; Vazquez-Mena, Oscar; Bertsch, Arnaud; Brugger, Juergen; Renaud, Philippe

    2012-08-01

    Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al2O3/SiO2 (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al2O3 (positive) and SiO2 (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion.Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al2O3/SiO2 (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al2O3

  11. 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

  12. Membrane-Mediated Aggregation of Curvature-Inducing Nematogens and Membrane Tubulation

    PubMed Central

    Ramakrishnan, N.; Sunil Kumar, P.B.; Ipsen, John H.

    2013-01-01

    The shapes of cell membranes are largely regulated by membrane-associated, curvature-active proteins. Herein, we use a numerical model of the membrane, recently developed by us, with elongated membrane inclusions possessing spontaneous directional curvatures that could be different along, and perpendicular to, the membrane’s long axis. We show that, due to membrane-mediated interactions, these curvature-inducing membrane-nematogens can aggregate spontaneously, even at low concentrations, and change the local shape of the membrane. We demonstrate that for a large group of such inclusions, where the two spontaneous curvatures have equal sign, the tubular conformation and sometimes the sheet conformation of the membrane are the common equilibrium shapes. We elucidate the factors necessary for the formation of these protein lattices. Furthermore, the elastic properties of the tubes, such as their compressional stiffness and persistence length, are calculated. Finally, we discuss the possible role of nematic disclination in capping and branching of the tubular membranes. PMID:23473484

  13. 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.

  14. Low-cost tubular antenna deployer for WISP-2

    NASA Technical Reports Server (NTRS)

    Warden, Robert M.

    1995-01-01

    A new tubular boom deployment mechanism has been designed, built, and flown as part of the second Waves In Space Program (WISP-2) through Cornell University. For this program, two booms were needed to form a dipole antenna but existing units were found to be too complicated and costly. A low-cost alternative was developed which combined flight-proven tubular boom technology with a new support and deployment mechanism. The simplicity of this new design was a major factor in providing a highly reliable and cost-effective system.

  15. 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.

  16. Multi-membrane hydrogels.

    PubMed

    Ladet, Sébastien; David, Laurent; Domard, Alain

    2008-03-06

    Polysaccharide-based hydrogels are useful for numerous applications, from food and cosmetic processing to drug delivery and tissue engineering. The formation of hydrogels from polyelectrolyte solutions is complex, involving a variety of molecular interactions. The physical gelation of polysaccharides can be achieved by balancing solvophobic and solvophilic interactions. Polymer chain reorganization can be obtained by solvent exchange, one of the processing routes forming a simple hydrogel assembly. Nevertheless, many studies on hydrogel formation are empirical with a limited understanding of the mechanisms involved, delaying the processing of more complex structures. Here we use a multi-step interrupted gelation process in controlled physico-chemical conditions to generate complex hydrogels with multi-membrane 'onion-like' architectures. Our approach greatly simplifies the processing of gels with complex shapes and a multi-membrane organization. In contrast with existing assemblies described in the literature, our method allows the formation of free 'inter-membrane' spaces well suited for cell or drug introduction. These architectures, potentially useful in biomedical applications, open interesting perspectives by taking advantage of tailor-made three-dimensional multi-membrane tubular or spherical structures.

  17. Vancomycin induces reactive oxygen species-dependent apoptosis via mitochondrial cardiolipin peroxidation in renal tubular epithelial cells.

    PubMed

    Sakamoto, Yuya; Yano, Takahisa; Hanada, Yuki; Takeshita, Aki; Inagaki, Fumika; Masuda, Satohiro; Matsunaga, Naoya; Koyanagi, Satoru; Ohdo, Shigehiro

    2017-04-05

    Vancomycin (VCM) is a first-line antibiotic for serious infections caused by methicillin-resistant Staphylococcus aureus. However, nephrotoxicity is one of the most complaint in VCM therapy. We previously reported that VCM induced apoptosis in a porcine proximal tubular epithelial cell line (LLC-PK1), in which mitochondrial complex I may generate superoxide, leading to cell death. In the present study, VCM caused production of mitochondrial reactive oxygen species and peroxidation of the mitochondrial phospholipid cardiolipin that was reversed by administration of the mitochondrial uncoupler carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP). FCCP also significantly suppressed VCM-induced depolarization of the mitochondrial membrane and apoptosis. Moreover, the lipophilic antioxidant vitamin E and a mitochondria-targeted antioxidant, mitoTEMPO, also significantly suppressed VCM-induced depolarization of mitochondrial membrane and apoptosis, whereas vitamin C, n-acetyl cysteine, or glutathione did not provide significant protection. These findings suggest that peroxidation of the mitochondrial membrane cardiolipin mediated the VCM-induced production of intracellular reactive oxygen species and initiation of apoptosis in LLC-PK1 cells. Furthermore, regulation of mitochondrial function using a mitochondria-targeted antioxidant, such as mitoTEMPO, may constitute a potential strategy for mitigation of VCM-induced proximal tubular epithelial cell injury.

  18. Alpha-enolase on apical surface of renal tubular epithelial cells serves as a calcium oxalate crystal receptor

    NASA Astrophysics Data System (ADS)

    Fong-Ngern, Kedsarin; Thongboonkerd, Visith

    2016-10-01

    To search for a strategy to prevent kidney stone formation/recurrence, this study addressed the role of α-enolase on apical membrane of renal tubular cells in mediating calcium oxalate monohydrate (COM) crystal adhesion. Its presence on apical membrane and in COM crystal-bound fraction was confirmed by Western blotting and immunofluorescence staining. Pretreating MDCK cells with anti-α-enolase antibody, not isotype-controlled IgG, dramatically reduced cell-crystal adhesion. Immunofluorescence staining also confirmed the direct binding of purified α-enolase to COM crystals at {121} > {100} > {010} crystal faces. Coating COM crystals with urinary proteins diminished the crystal binding capacity to cells and purified α-enolase. Moreover, α-enolase selectively bound to COM, not other crystals. Chemico-protein interactions analysis revealed that α-enolase interacted directly with Ca2+ and Mg2+. Incubating the cells with Mg2+ prior to cell-crystal adhesion assay significantly reduced crystal binding on the cell surface, whereas preincubation with EDTA, a divalent cation chelator, completely abolished Mg2+ effect, indicating that COM and Mg2+ competitively bind to α-enolase. Taken together, we successfully confirmed the role of α-enolase as a COM crystal receptor to mediate COM crystal adhesion at apical membrane of renal tubular cells. It may also serve as a target for stone prevention by blocking cell-crystal adhesion and stone nidus formation.

  19. Changes in free and esterified cholesterol: hallmarks of acute renal tubular injury and acquired cytoresistance.

    PubMed

    Zager, R A; Kalhorn, T F

    2000-09-01

    Acute tubular cell injury is accompanied by plasma membrane phospholipid breakdown. Although cholesterol is a dominant membrane lipid which interdigitates with, and impacts, phospholipid homeostasis, its fate during the induction and recovery phases of acute renal failure (ARF) has remained ill defined. The present study was performed to ascertain whether altered cholesterol expression is a hallmark of evolving tubular damage. Using gas chromatographic analysis, free cholesterol (FC) and esterified cholesterol (CE) were quantified in: 1) isolated mouse proximal tubule segments (PTS) after 30 minutes of hypoxic or oxidant (ferrous ammonium sulfate) injury; 2) cultured proximal tubule (HK-2) cells after 4 or 18 hours of either ATP depletion/Ca(2+) ionophore- or ferrous ammonium sulfate-mediated injury; and 3) in renal cortex 18 hours after induction of glycerol-induced myoglobinuric ARF, a time corresponding to the so-called "acquired cytoresistance" state (ie, resistance to further renal damage). Hypoxic and oxidant injury each induced approximately 33% decrements in CE (but not FC) levels in PTS, corresponding with lethal cell injury ( approximately 50 to 60% LDH release). When comparable CE declines were induced in normal PTS by exogenous cholesterol esterase treatment, proportionate lethal cell injury resulted. During models of slowly evolving HK-2 cell injury, progressive CE increments occurred: these were first noted at 4 hours, and reached approximately 600% by 18 hours. In vivo myoglobinuric ARF produced comparable renal cortical CE (and to a lesser extent FC) increments. Renal CE accumulation strikingly correlated with the severity of ARF (eg, blood urea nitrogen versus CE; r, 0.84). Mevastatin blocked cholesterol accumulation in injured HK-2 cells, indicating de novo synthesis was responsible. Acute tubule injury first lowers, then raises, tubule cholesterol content. Based on previous observations that cholesterol has cytoprotectant properties, the present

  20. Development of Inorganic Membranes for Hydrogen Separation

    SciTech Connect

    Bischoff, Brian L; Adcock, Kenneth Dale; Powell, Lawrence E; Sutton, Theodore G; Miller, Curtis Jack

    2007-01-01

    The purpose of this work is to improve the method of fabricating tubular metal supported microporous inorganic membranes. Earlier work focused on the original development of inorganic membranes for the purification of hydrogen. These membranes are now being scaled up for demonstration in a coal gasification plant for the separation of hydrogen from coal-derived synthesis gas for a project funded by the Office of Fossil Energy's Gasification and Coal Fuels programs [1]. This project is part of FutureGen, an initiative to build the world's first integrated sequestration and hydrogen production research power plant. Although previous work in the Advanced Research Materials Program project led to development of a tubular metal supported microporous membrane which was approved by the Department of Energy for testing, the membranes generally have lower than desired selectivities for hydrogen over other gases common in synthesis gas including carbon dioxide. The work on this project over three years will lead to general improvements in fabrication techniques that will result in membranes having higher separation factors and higher fluxes. Scanning electron microscopy and profilometry data will be presented to show qualitatively and quantitatively the surface roughness of the support tubes. We will discuss how the roughness affects membrane quality and methods to improve the quality of the support tube surface.

  1. A high-performance and low cost SERS substrate of plasmonic nanopillars on plastic film fabricated by nanoimprint lithography with AAO template

    NASA Astrophysics Data System (ADS)

    Liu, Long; Zhang, Qian; Lu, Yuanshen; Du, Wei; Li, Bin; Cui, Yushuang; Yuan, Changsheng; Zhan, Peng; Ge, Haixiong; Wang, Zhenling; Chen, Yanfeng

    2017-06-01

    As a powerful spectroscopy technique, surface-enhanced Raman scattering (SERS) can provide non-destructive and sensitive characterization down to a single molecular level. Aiming to the main challenges of high-performance SERS-active substrates for their real-world applications involving the ultra-sensitive and reproducible signals detection and signal uniformity with large-area, herein, a facile and reliable strategy based on combination of thermal imprinting polycarbonate (PC) film with porous anodic aluminum oxide (AAO) mold and E-beam evaporation of gold is provided to fabricate a high-quality SERS-active substrate consisting of ultra-dense hot-spots with large-area uniformity. Two kinds of sub-10 nm gaps were obtained, including the nanogaps between the neighboring gold coated PC-nanopillars and those between gold on the top of the nanopillars and that on the base, which actually build up a three-dimensional (3D) hot-spot network for high-performance SERS detection. The effect of structural parameters on SERS enhancement was investigated numerically and experimentally, and by optimizing the structural parameters, a remarkable average SERS enhancement factor up to of 1.4×108 is achieved and it shows an excellent reproducibility with a relative standard deviation of 18%, which allows for enhanced practicability in the application of quantitative biochemical detection.

  2. SNX–BAR proteins in phosphoinositide-mediated, tubular-based endosomal sorting

    PubMed Central

    van Weering, Jan R.T.; Verkade, Paul; Cullen, Peter J.

    2014-01-01

    The endocytic network is morphologically characterized by a wide variety of membrane bound compartments that are able to undergo dynamic re-modeling through tubular and vesicular structures. The precise molecular mechanisms governing such re-modeling, and the events that co-ordinated this with the major role of the endocytic network, cargo sorting, remain unclear. That said, recent work on a protein family of sorting nexins (SNX) – especially a subfamily of SNX that contain a BAR domain (SNX–BARs) – has begun to shed some much needed light on these issues and in particular the process of tubular–based endosomal sorting. SNX–BARs are evolutionary conserved in endosomal protein complexes such as retromer, where they co–ordinate membrane deformation with cargo selection. Furthermore a central theme emerges of SNX–BARs linking the forming membrane carrier to cytoskeletal elements for transport through motor proteins such as dynein. By studying these SNX–BARs, we are gaining an increasingly detailed appreciation of the mechanistic basis of endosomal sorting and how this highly dynamic process functions in health and disease. PMID:19914387

  3. A Case Report of a Giant Tubular Adenoma With a Concurrent Fibroadenoma of the Breast

    PubMed Central

    Kalipatnapu, Sasank; Samuel, Vimalin; Johnson, Martha; Perookavil Daniel, Koshy

    2015-01-01

    Tubular adenomas are rare benign epithelial tumors of the breast. Only a handful of cases have been reported in literature. We describe a very rare case of a giant tubular adenoma with a concurrent fibroadenoma in a young woman.

  4. Hollow tubular porous covalent organic framework (COF) nanostructures.

    PubMed

    Pachfule, Pradip; Kandmabeth, Sharath; Mallick, Arijit; Banerjee, Rahul

    2015-07-25

    Hollow and tubular TpPa-COF structures have been synthesized by template-assisted replication of nanometer sized ZnO-nanorods. The hollow structures composed of microporous TpPa shells have high periodicity, moderate porosity, chemical stability and capsule shaped morphology as revealed by X-ray diffraction, porosity measurements, and SEM and TEM analyses.

  5. Tubular surface segmentation for extracting anatomical structures from medical imagery.

    PubMed

    Mohan, Vandana; Sundaramoorthi, Ganesh; Tannenbaum, Allen

    2010-12-01

    This work provides a model for tubular structures, and devises an algorithm to automatically extract tubular anatomical structures from medical imagery. Our model fits many anatomical structures in medical imagery, in particular, various fiber bundles in the brain (imaged through diffusion-weighted magnetic resonance (DW-MRI)) such as the cingulum bundle, and blood vessel trees in computed tomography angiograms (CTAs). Extraction of the cingulum bundle is of interest because of possible ties to schizophrenia, and extracting blood vessels is helpful in the diagnosis of cardiovascular diseases. The tubular model we propose has advantages over many existing approaches in literature: fewer degrees-of-freedom over a general deformable surface hence energies defined on such tubes are less sensitive to undesirable local minima, and the tube (in 3-D) can be naturally represented by a 4-D curve (a radius function and centerline), which leads to computationally less costly algorithms and has the advantage that the centerline of the tube is obtained without additional effort. Our model also generalizes to tubular trees, and the extraction algorithm that we design automatically detects and evolves branches of the tree. We demonstrate the performance of our algorithm on 20 datasets of DW-MRI data and 32 datasets of CTA, and quantify the results of our algorithm when expert segmentations are available.

  6. 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.

  7. Cystinosis (ctns) zebrafish mutant shows pronephric glomerular and tubular dysfunction

    PubMed Central

    Elmonem, Mohamed A.; Khalil, Ramzi; Khodaparast, Ladan; Khodaparast, Laleh; Arcolino, Fanny O.; Morgan, Joseph; Pastore, Anna; Tylzanowski, Przemko; Ny, Annelii; Lowe, Martin; de Witte, Peter A.; Baelde, Hans J.; van den Heuvel, Lambertus P.; Levtchenko, Elena

    2017-01-01

    The human ubiquitous protein cystinosin is responsible for transporting the disulphide amino acid cystine from the lysosomal compartment into the cytosol. In humans, Pathogenic mutations of CTNS lead to defective cystinosin function, intralysosomal cystine accumulation and the development of cystinosis. Kidneys are initially affected with generalized proximal tubular dysfunction (renal Fanconi syndrome), then the disease rapidly affects glomeruli and progresses towards end stage renal failure and multiple organ dysfunction. Animal models of cystinosis are limited, with only a Ctns knockout mouse reported, showing cystine accumulation and late signs of tubular dysfunction but lacking the glomerular phenotype. We established and characterized a mutant zebrafish model with a homozygous nonsense mutation (c.706 C > T; p.Q236X) in exon 8 of ctns. Cystinotic mutant larvae showed cystine accumulation, delayed development, and signs of pronephric glomerular and tubular dysfunction mimicking the early phenotype of human cystinotic patients. Furthermore, cystinotic larvae showed a significantly increased rate of apoptosis that could be ameliorated with cysteamine, the human cystine depleting therapy. Our data demonstrate that, ctns gene is essential for zebrafish pronephric podocyte and proximal tubular function and that the ctns-mutant can be used for studying the disease pathogenic mechanisms and for testing novel therapies for cystinosis. PMID:28198397

  8. Molecular tectonics: tubular crystals with controllable channel size and orientation.

    PubMed

    Lin, Mei-Jin; Jouaiti, Abdelaziz; Pocic, David; Kyritsakas, Nathalie; Planeix, Jean-Marc; Hosseini, Mir Wais

    2010-01-07

    The combination of flexible neutral organic tectons based on two pyridines interconnected by a thioether or thioester type spacer with an inorganic ZnSiF(6) pillar leads to the formation of 2-D coordination networks and the packing of the latter generates crystals offering controllable tubular channels with imposed orientation along the pillar axis.

  9. On the flooding limit in the evaporative, tubular thermosyphon

    NASA Astrophysics Data System (ADS)

    Lock, G. S. H.

    1993-02-01

    The note provides an appraisal of the essential physics accompanying the flooding limit in the evaporative, tubular thermosyphon. It is suggested that flooding is characterized, in general, by a balance between inertial, buoyancy and surface tension forces acting on curved liquid-vapor interfaces. The fundamental role of the Bond, Froude, Weber and Kutateladze numbers is discussed.

  10. Renal tubular leakage complicating microcephalic osteodysplastic primordial dwarfism.

    PubMed Central

    Eason, J; Hall, C M; Trounce, J Q

    1995-01-01

    We describe a male infant with phenotypic and radiological features of microcephalic osteodysplastic primordial dwarfism type I/III. He showed severe osteoporosis and biochemical derangement owing to renal tubular leakage, which has not previously been reported in this condition. He died aged 5 months. Images PMID:7783178

  11. 75 FR 3248 - Certain Oil Country Tubular Goods From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-20

    ... COMMISSION Certain Oil Country Tubular Goods From China Determination On the basis of the record \\1... industry in the United States is threatened with material injury by reason of imports from China of certain... Commerce ] (Commerce) to be subsidized by the Government of China. 2 3 \\1\\ The record is defined in...

  12. Albumin Is Recycled from the Primary Urine by Tubular Transcytosis

    PubMed Central

    Tenten, Verena; Menzel, Sylvia; Kunter, Uta; Sicking, Eva-Maria; van Roeyen, Claudia R. C.; Sanden, Silja K.; Kaldenbach, Michaela; Boor, Peter; Fuss, Astrid; Uhlig, Sandra; Lanzmich, Regina; Willemsen, Brigith; Dijkman, Henry; Grepl, Martin; Wild, Klemens; Kriz, Wilhelm; Smeets, Bart; Floege, Jürgen

    2013-01-01

    Under physiologic conditions, significant amounts of plasma protein pass the renal filter and are reabsorbed by proximal tubular cells, but it is not clear whether the endocytosed protein, particularly albumin, is degraded in lysosomes or returned to the circulatory system intact. To resolve this question, a transgenic mouse with podocyte-specific expression of doxycycline-inducible tagged murine albumin was developed. To assess potential glomerular backfiltration, two types of albumin with different charges were expressed. On administration of doxycycline, podocytes expressed either of the two types of transgenic albumin, which were secreted into the primary filtrate and reabsorbed by proximal tubular cells, resulting in serum accumulation. Renal transplantation experiments confirmed that extrarenal transcription of transgenic albumin was unlikely to account for these results. Genetic deletion of the neonatal Fc receptor (FcRn), which rescues albumin and IgG from lysosomal degradation, abolished transcytosis of both types of transgenic albumin and IgG in proximal tubular cells. In summary, we provide evidence of a transcytosis within the kidney tubular system that protects albumin and IgG from lysosomal degradation, allowing these proteins to be recycled intact. PMID:23970123

  13. 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)

  14. Renal pathophysiologic role of cortical tubular inclusion bodies.

    PubMed

    Radi, Zaher A; Stewart, Zachary S; Grzemski, Felicity A; Bobrowski, Walter F

    2013-01-01

    Renal tubular inclusion bodies are rarely associated with drug administration. The authors describe the finding of renal cortical tubular intranuclear and intracytoplasmic inclusion bodies associated with the oral administration of a norepinephrine/serotonin reuptake inhibitor (NSRI) test article in Sprague-Dawley (SD) rats. Rats were given an NSRI daily for 4 weeks, and kidney histopathologic, ultrastructural pathology, and immunohistochemical examinations were performed. Round eosinophilic intranuclear inclusion bodies were observed histologically in the tubular epithelial cells of the renal cortex in male and female SD rats given the NSRI compound. No evidence of degeneration or necrosis was noted in the inclusion-containing renal cells. By ultrastructural pathology, inclusion bodies consisted of finely granular, amorphous, and uniformly stained nonmembrane-bound material. By immunohistochemistry, inclusion bodies stained positive for d-amino acid oxidase (DAO) protein. In addition, similar inclusion bodies were noted in the cytoplasmic tubular epithelial compartment by ultrastructural and immunohistochemical examination.  This is the first description of these renal inclusion bodies after an NSRI test article administration in SD rats. Such drug-induced renal inclusion bodies are rat-specific, do not represent an expression of nephrotoxicity, represent altered metabolism of d-amino acids, and are not relevant to human safety risk assessment.

  15. Column compression strength of tubular packaging forms made from paper

    Treesearch

    Thomas J. Urbanik; Sung K. Lee; Charles G. Johnson

    2006-01-01

    Tubular packaging forms fabricated and shaped from rolled paper are used as reinforcing corner posts for major appliances packaged in corrugated containers. Tests of column compression strength simulate the expected performance loads from appliances stacked in warehouses. Column strength depends on tube geometry, paper properties, basis weight, and number of...

  16. Osteomalacia associated with increased renal tubular resorption of phosphate (hypohyperparathyroidism)

    PubMed Central

    Kanis, J. A.; Walton, R. J.

    1976-01-01

    A 12-year-old girl, who presented with joint pains, was found to have hypocalcaemia, hyperphosphataemia due to increased renal tubular reabsorption, increased serum alkaline phosphatase activity, and osteomalacia. These features, which resemble those found in so-called hypohyperparathyroidism, were all rapidly reversed by small doses of cholecalciferol. PMID:183195

  17. Tubular Surface Segmentation for Extracting Anatomical Structures From Medical Imagery

    PubMed Central

    Sundaramoorthi, Ganesh; Tannenbaum, Allen

    2011-01-01

    This work provides a model for tubular structures, and devises an algorithm to automatically extract tubular anatomical structures from medical imagery. Our model fits many anatomical structures in medical imagery, in particular, various fiber bundles in the brain (imaged through diffusion-weighted magnetic resonance (DW-MRI)) such as the cingulum bundle, and blood vessel trees in computed tomography angiograms (CTAs). Extraction of the cingulum bundle is of interest because of possible ties to schizophrenia, and extracting blood vessels is helpful in the diagnosis of cardiovascular diseases. The tubular model we propose has advantages over many existing approaches in literature: fewer degrees-of-freedom over a general deformable surface hence energies defined on such tubes are less sensitive to undesirable local minima, and the tube (in 3-D) can be naturally represented by a 4-D curve (a radius function and centerline), which leads to computationally less costly algorithms and has the advantage that the centerline of the tube is obtained without additional effort. Our model also generalizes to tubular trees, and the extraction algorithm that we design automatically detects and evolves branches of the tree. We demonstrate the performance of our algorithm on 20 datasets of DW-MRI data and 32 datasets of CTA, and quantify the results of our algorithm when expert segmentations are available. PMID:21118754

  18. Tubular Ectasia of the Rete Testis: A Diagnostic Dilemma

    PubMed Central

    Nair, Rajesh; Abbaraju, J; Rajbabu, K; Anjum, F; Sriprasad, S

    2008-01-01

    Tubular ectasia of the rete testis is a pathologically benign process with complex and varied aetiology. It must be differentiated from neoplastic disease of the testis clinically with patient age, mode of presentation, tumour marker status and the characteristic ultrasound and Doppler study findings. Awareness and diagnosis of this clinical entity can prevent unnecessary surgical intervention in these patients. PMID:18831860

  19. Chloride currents from the transverse tubular system in adult mammalian skeletal muscle fibers

    PubMed Central

    DiFranco, Marino; Herrera, Alvaro

    2011-01-01

    Chloride fluxes are the main contributors to the resting conductance of mammalian skeletal muscle fibers. ClC-1, the most abundant chloride channel isoform in this preparation, is believed to be responsible for this conductance. However, the actual distribution of ClC-1 channels between the surface and transverse tubular system (TTS) membranes has not been assessed in intact muscle fibers. To investigate this issue, we voltageclamped enzymatically dissociated short fibers using a two-microelectrode configuration and simultaneously recorded chloride currents (ICl) and di-8-ANEPPS fluorescence signals to assess membrane potential changes in the TTS. Experiments were conducted in conditions that blocked all but the chloride conductance. Fibers were equilibrated with 40 or 70 mM intracellular chloride to enhance the magnitude of inward ICl, and the specific ClC-1 blocker 9-ACA was used to eliminate these currents whenever necessary. Voltage-dependent di-8-ANEPPS signals and ICl acquired before (control) and after the addition of 9-ACA were comparatively assessed. Early after the onset of stimulus pulses, di-8-ANEPPS signals under control conditions were smaller than those recorded in the presence of 9-ACA. We defined as attenuation the normalized time-dependent difference between these signals. Attenuation was discovered to be ICl dependent since its magnitude varied in close correlation with the amplitude and time course of ICl. While the properties of ICl, and those of the attenuation seen in optical records, could be simultaneously predicted by model simulations when the chloride permeability (PCl) at the surface and TTS membranes were approximately equal, the model failed to explain the optical data if PCl was precluded from the TTS membranes. Since the ratio between the areas of TTS membranes and the sarcolemma is large in mammalian muscle fibers, our results demonstrate that a significant fraction of the experimentally recorded ICl arises from TTS contributions

  20. Double breasting spongioplasty in tubularized/tubularized incise plate urethroplasty: A new technique

    PubMed Central

    Bhat, Amilal; Bhat, Mahakshit; Kumar, Rajeev; Bhat, Akshita

    2017-01-01

    Introduction: The main disadvantage of currently described techniques of spongioplasty is superimposition of 3 suture lines (neourethra, spongioplasty, and skin closure) which is likely to increase the chances of a fistula. We describe and evaluate the results of a double breasting spongioplasty in urethroplasty. Methods: A prospective study of 60 primary hypospadias was undertaken by double breasting spongioplasty from August 2012 to March 2014. Mobilization of the urethral plate and the spongiosum is done by creating a plane just proximal to the meatus. Double breasting spongioplasty is done after tubularization of urethral plate. First layer of spongiosum is sutured toward lateral side of the neourethra covering the suture line. A second double breasting layer is sutured over the first layer with its suture line toward the opposite side covering the suture line of the first layer; thus avoiding overlapping of suture lines of all the three layers. Results: Age of the patients varied from 10 months to 16 years with a mean and median of 3.73 and 3.50 years, respectively. Hypospadias was distal, mid, and proximal in 38, 10, and 12 cases, respectively. Chordee was noticed in 35 cases and torque in 28 cases. Overall complication rate was 5% and fistula rate was 1.66%. Conclusions: Double breasting spongioplasty avoids superimposition of suture line and adds two layers of spongiosum over neourethra, thus decreases the chances of urethral fistula and gives cylindrical shape to neourethra. PMID:28197032

  1. Geochemical characterization of tubular alteration features in subseafloor basalt glass

    NASA Astrophysics Data System (ADS)

    Knowles, Emily; Staudigel, Hubert; Templeton, Alexis

    2013-07-01

    There are numerous indications that subseafloor basalts may currently host a huge quantity of active microbial cells and contain biosignatures of ancient life in the form of physical and chemical basalt glass alteration. Unfortunately, technological challenges prevent us from observing the formation and mineralization of these alteration features in situ, or reproducing tubular basalt alteration processes in the laboratory. Therefore, comprehensive analysis of the physical and chemical traces retained in mineralized tubules is currently the best approach for deciphering a record of glass alteration. We have used a number of high-resolution spectroscopic and microscopic methods to probe the geochemical and mineralogical characteristics of tubular alteration features in basalt glasses obtained from a suite of subseafloor drill cores that covers a range of different collection locations and ages. By combining three different synchrotron-based X-ray measurements - X-ray fluorescence microprobe mapping, XANES spectroscopy, and μ-XRD - with focused ion beam milling and transmission electron microscopy, we have spatially resolved the major and trace element distributions, as well as the oxidation state of Fe, determined the coordination chemistry of Fe, Mn and Ti at the micron-scale, and constrained the secondary minerals within these features. The tubular alteration features are characterized by strong losses of Fe2+, Mn2+, and Ca2+ compared to fresh glass, oxidation of the residual Fe, and the accumulation of Ti and Cu. The predominant phases infilling the alteration regions are Fe3+-bearing silicates dominated by 2:1 clays, with secondary Fe- and Ti-oxides, and a partially oxidized Mn-silicate phase. These geochemical patterns observed within the tubular alteration features are comparable across a diverse suite of samples formed over the past 5-100 Ma, which shows that the microscale mineralization processes are common and consistent throughout the ocean basins and

  2. 75 FR 28058 - Certain Oil Country Tubular Goods From China; Determination

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-19

    ... 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 7306...), entitled Certain Oil Country Tubular Goods From China: Investigation No. 731-TA- 1159 (Final). By order of...

  3. Renal tubular function in children with beta-thalassemia minor.

    PubMed

    Kalman, Süleyman; Atay, A Avni; Sakallioglu, Onur; Ozgürtaş, Taner; Gök, Faysal; Kurt, Ismail; Kürekçi, A Emin; Ozcan, Okan; Gökçay, Erdal

    2005-10-01

    beta-thalassemia minor is a common heterozygous haemoglobinopathy that is characterized by both microcytosis and hypochromia. It requires no treatment. It has been postulated that low-grade haemolysis, tubular iron deposition and toxins derived from erythrocytes might cause renal tubular damage in adult patients with beta-thalassemia minor. Our aim was to investigate the renal tubular functions in children with beta-thalassemia minor and to determine its possible harmful effects. The study was conducted on 32 children (14 female and 18 male) at the age of 5.8 +/- 3.1 years (range 2-14 years) with beta-thalassemia minor. The patients were classified as anaemic (haemoglobin (Hb) 11 g/dL) (Group 2, n = 18). A control group was formed with 18 healthy children whose ages and sexes match those in other groups (Group 3, n = 18). Fractional excretion of sodium (FE(Na), %), fractional excretion of magnesium (FE(Mg), %), fractional excretion of uric acid (FE(UA), %) and tubular phosphorus reabsorption (TPR,%) were calculated with standard formulas. Urinary calcium excretion (mg/kg per 24 h), zinc (Zn) (microg/dL), glucosuria (mg/dL), beta-2 microglobulin (mg/dL) and N-acetyl-beta-D-glycosaminidase (NAG, U/mmol creatinine) levels were measured through biochemical methods. There was no statistically significant difference among the three groups in terms of the results of FE(Na) (%), FE(Mg) (%), FE(UA) (%), TPR (%), calciuria (mg/kg per 24 h), NAG, urine Zn, proteinuria, glucosuria or urine beta- 2 microglobulin levels (P > 0.05). On the contrary of children with beta-thalassemia major, renal tubular dysfunction has not been determined in children with beta-thalassemia minor in the present study.

  4. sup 99m Tc renal tubular function agents: Current status

    SciTech Connect

    Eshima, D.; Fritzberg, A.R.; Taylor, A. Jr. )

    1990-01-01

    Orthoiodohippuric (OIH) acid labeled with 131I is a widely used renal radiopharmaceutical agent and has been the standard radiopharmaceutical agent for the measurement of effective renal plasma flow (EPRF). Limitations to the routine clinical use of 131I OIH are related to the suboptimal imaging properties of the 131I radionuclide and its relatively high radiation dose. 123I has been substituted for 131I; however, its high cost and short shelf-life have limited its widespread use. Recent work has centered on the development of a new 99mTc renal tubular function agent, which would use the optimal radionuclidic properties and availability of 99mTc and combine the clinical information provided by OIH. The search for a suitable 99mTc renal tubular function agent has focused on the diamide dithiolate (N2S2), the paraaminohippuric iminodiacetic acid (PAHIDA), and the triamide mercaptide (N3S) donor ligand systems. To date, the most promising 99mTc tubular function agent is the N3S complex: 99mTc mercaptoacetyltriglycine (99mTc MAG3). Studies in animal models in diuresis, dehydration, acid or base imbalance, ischemia, and renal artery stenosis demonstrate that 99mTc MAG3 behaves similarly to 131I OIH. A simple kit formulation is available that yields the 99mTc MAG3 complex in high radiochemical purity. Studies in normal subjects and patients indicate that 99mTc MAG3 is an excellent 99mTc renal tubular agent, but its plasma clearance is only 50% to 60% that of OIH. In an effort to develop an improved 99mTc renal tubular function agent, changes have been made in the core N3S donor ligand system, but to date no agent has been synthesized that is clinically superior to 99mTc MAG3. 61 references.

  5. Biodegradable mesostructured polymer membranes

    PubMed Central

    Tian, Bozhi; Shankarappa, Sahadev; Chang, Homer H.; Tong, Rong; Kohane, Daniel S.

    2013-01-01

    The extracellular matrix (ECM) has a quasi-ordered reticular mesostructure with feature sizes on the order of tenths of to a few hundred nanometers. Approaches to preparing biodegradable synthetic scaffolds for engineered tissues that have the critical mesostructure to mimic ECM are few. Here we present a simple and general solvent evaporation-induced self-assembly (EISA) approach to preparing concentrically reticular mesostructured polyol-polyester membranes. The mesostructures were formed by a novel self-assembly process without covalent or electrostatic interactions, which yielded feature sizes matching those of ECM. The mesostructured materials were nonionic, hydrophilic, and water-permeable, and could be shaped into arbitrary geometries such as conformally-molded tubular sacs and micropatterned meshes. Importantly, the mesostructured polymers were biodegradable, and were used as ultrathin temporary substrates for engineering vascular tissue constructs. PMID:23964960

  6. Biodegradable mesostructured polymer membranes.

    PubMed

    Tian, Bozhi; Shankarappa, Sahadev A; Chang, Homer H; Tong, Rong; Kohane, Daniel S

    2013-09-11

    The extracellular matrix (ECM) has a quasi-ordered reticular mesostructure with feature sizes on the order of tenths of to a few hundred nanometers. Approaches to preparing biodegradable synthetic scaffolds for engineered tissues that have the critical mesostructure to mimic ECM are few. Here we present a simple and general solvent evaporation-induced self-assembly (EISA) approach to preparing concentrically reticular mesostructured polyol-polyester membranes. The mesostructures were formed by a novel self-assembly process without covalent or electrostatic interactions, which yielded feature sizes matching those of ECM. The mesostructured materials were nonionic, hydrophilic, and water-permeable and could be shaped into arbitrary geometries such as conformally molded tubular sacs and micropatterned meshes. Importantly, the mesostructured polymers were biodegradable and were used as ultrathin temporary substrates for engineering vascular tissue constructs.

  7. Calcium Dyshomeostasis in Tubular Aggregate Myopathy

    PubMed Central

    Lee, Jong-Mok; Noguchi, Satoru

    2016-01-01

    Calcium is a crucial mediator of cell signaling in skeletal muscles for basic cellular functions and specific functions, including contraction, fiber-type differentiation and energy production. The sarcoplasmic reticulum (SR) is an organelle that provides a large supply of intracellular Ca2+ in myofibers. Upon excitation, it releases Ca2+ into the cytosol, inducing contraction of myofibrils. During relaxation, it takes up cytosolic Ca2+ to terminate the contraction. During exercise, Ca2+ is cycled between the cytosol and the SR through a system by which the Ca2+ pool in the SR is restored by uptake of extracellular Ca2+ via a specific channel on the plasma membrane. This channel is called the store-operated Ca2+ channel or the Ca2+ release-activated Ca2+ channel. It is activated by depletion of the Ca2+ store in the SR by coordination of two main molecules: stromal interaction molecule 1 (STIM1) and calcium release-activated calcium channel protein 1 (ORAI1). Recently, myopathies with a dominant mutation in these genes have been reported and the pathogenic mechanism of such diseases have been proposed. This review overviews the calcium signaling in skeletal muscles and role of store-operated Ca2+ entry in calcium homeostasis. Finally, we discuss the phenotypes and the pathomechanism of myopathies caused by mutations in the STIM1 and ORAI1 genes. PMID:27879676

  8. Albumin-bound fatty acids but not albumin itself alter redox balance in tubular epithelial cells and induce a peroxide-mediated redox-sensitive apoptosis.

    PubMed

    Ruggiero, Christine; Elks, Carrie M; Kruger, Claudia; Cleland, Ellen; Addison, Kaity; Noland, Robert C; Stadler, Krisztian

    2014-04-15

    Albuminuria is associated with metabolic syndrome and diabetes. It correlates with the progression of chronic kidney disease, particularly with tubular atrophy. The fatty acid load on albumin significantly increases in obesity, presenting a proinflammatory environment to the proximal tubules. However, little is known about changes in the redox milieu during fatty acid overload and how redox-sensitive mechanisms mediate cell death. Here, we show that albumin with fatty acid impurities or conjugated with palmitate but not albumin itself compromised mitochondrial and cell viability, membrane potential and respiration. Fatty acid overload led to a redox imbalance which deactivated the antioxidant protein peroxiredoxin 2 and caused a peroxide-mediated apoptosis through the redox-sensitive pJNK/caspase-3 pathway. Transfection of tubular cells with peroxiredoxin 2 was protective and mitigated apoptosis. Mitochondrial fatty acid entry and ceramide synthesis modulators suggested that mitochondrial β oxidation but not ceramide synthesis may modulate lipotoxic effects on tubular cell survival. These results suggest that albumin overloaded with fatty acids but not albumin itself changes the redox environment in the tubules, inducing a peroxide-mediated redox-sensitive apoptosis. Thus, mitigating circulating fatty acid levels may be an important factor in both preserving redox balance and preventing tubular cell damage in proteinuric diseases.

  9. DC-SIGN reacts with TLR4 and regulates inflammatory cytokine expression via NF-κB activation in renal tubular epithelial cells during acute renal injury.

    PubMed

    Feng, Danying; Wang, Yanping; Liu, Yan; Wu, Liping; Li, Xiao; Chen, Yufan; Chen, Yuanyuan; Chen, Yafeng; Xu, Chundi; Yang, Ke; Zhou, Tong

    2017-09-12

    In the pathological process of acute kidney injury (AKI), innate immune receptors are essential in inflammatory response modulation; however, the precise molecular mechanisms are still unclear. Our study sought to demonstrate the inflammatory response mechanisms in renal tubular epithelial cells via Toll-like receptor 4 (TLR4) and dendritic cell-specific ICAM-3-grabbing non-integrin 1 (DC-SIGN) signaling. We found that DC-SIGN exhibited strong expression in renal tubular epithelial cells of human acute renal injury tissues. DC-SIGN protein expression was significantly increased when renal tubular epithelial cells were exposed to lipopolysaccharide (LPS) for a short period. Furthermore, DC-SIGN was involved in the activation of p65 by TLR4, which excluded p38 and JNK. Interleukin 6 (IL-6) and tumor necrosis factor-α (TNFα) expression were decreased after DC-SIGN knockdown. Furthermore, LPS induced endogenous interactions and plasma membrane co-expression between TLR4 and DC-SIGN. These results showed that DC-SIGN and TLR4 interactions regulate inflammatory responses in renal tubular epithelial cells and participate in AKI pathogenesis. This article is protected by copyright. All rights reserved. © 2017 British Society for Immunology.

  10. 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.

  11. 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

  12. Serial block face SEM visualization of unusual plant nuclear tubular extensions in a carnivorous plant (Utricularia, Lentibulariaceae).

    PubMed

    Plachno, Bartosz J; Swiatek, Piotr; Jobson, Richard W; Malota, Karol; Brutkowski, Wojciech

    2017-05-24

    In Utricularia nelumbifolia , the nuclei of placental nutritive tissue possess unusually shaped projections not known to occur in any other flowering plant. The main aim of the study was to document the morphology and ultrastructure of these unusual nuclei. In addition, the literature was searched to find examples of nuclear tubular projections in other plant groups, and the nuclei of closely related species of Utricularia (i.e. sects Iperua , Orchidioides , Foliosa and Utricularia ) were examined. To visualize the complexity of the nuclear structures, transmission electron microscopy (TEM) was used, and 3-D ultrastructural reconstructions were made using the serial block face scanning electron microscopy (SBEM) technique. The nuclei of 11 Utricularia species, i.e. U. nelumbifolia , U. reniformis , U. cornigera , U. nephrophylla (sect. Iperua ), U. asplundii , U. alpina , U. quelchii (sect. Orchidioides ), U. longifolia (sect. Foliosa ), U. intermedia , U. minor and U. gibba (sect. Utricularia ) were examined. Of the 11 Utricularia species examined, the spindle-like tubular projections (approx. 5 μm long) emanating from resident nuclei located in placental nutritive tissues were observed only in U. nelumbifolia . These tubular nuclear extensions contained chromatin distributed along hexagonally shaped tubules. The apices of the projections extended into the cell plasma membrane, and in many cases also made contact at the two opposing cellular poles, and with plasmodesmata via a short cisterna of the cortical endoplasmic reticulum. Images from the SBEM provide some evidence that the nuclear projections are making contact with those of neighbouring cells. The term chromatubules (chromatin-filled tubules) for the nuclear projections of U. nelumbifolia placental tissue was proposed here. Due to the apparent association with the plasma membrane and plasmodesmata, it was also speculated that chromatubules are involved in nucleus-cell-cell communication. However

  13. Tenofovir is associated with increased tubular proteinuria and asymptomatic renal tubular dysfunction in Ghana.

    PubMed

    Chadwick, David R; Sarfo, Fred S; Kirk, Elaine S M; Owusu, Dorcas; Bedu-Addo, George; Parris, Victoria; Owusu, Ann Lorraine; Phillips, Richard

    2015-12-01

    HIV infection is associated with increased risk of renal dysfunction, including tubular dysfunction (TD) related to antiretroviral therapy (ART). Tenofovir disoproxil fumarate (TDF) is becoming available for ART in sub-Saharan Africa, although data on its long-term safety there is limited. We aimed to study the prevalence of HIV-associated renal dysfunction in Ghana and explore associations between proteinuria or TD and potential risk factors, including TDF use. A single-centre cross-sectional observational study of patients taking ART was undertaken. Creatinine clearance (CrCl) was calculated and proteinuria detected with dipsticks. Spot urinary albumin and protein:creatinine ratios (uACR/uPCR) were measured and further evidence of TD (defined as having two or more characteristic features) sought. Logistic regression analysis identified factors associated with proteinuria or TD. In 330 patients, of whom 101 were taking TDF (median 20 months), the prevalence of CrCl < 60 ml/min/1.73 m(2), dipstick proteinuria and TD was 7 %, 37 % and 15 %. Factors associated with proteinuria were baseline CD4-count [aOR 0.86/100 cell increment (95 % CI, 0.74-0.99)] and TDF use [aOR 2.74 (95 % CI, 1.38-5.43)]. The only factor associated with TD was TDF use [aOR 3.43 (95 % CI, 1.10-10.69)]. In a subset with uPCR measurements, uPCRs were significantly higher in patients taking TDF than those on other drugs (10.8 vs. 5.7 mg/mmol, p < 0.001), and urinary albuin:protein ratios significantly lower (0.24 vs. 0.58, p < 0.001). Both proteinuria and TD are common and associated with TDF use in Ghana. Further longitudinal studies to determine whether proteinuria, TD or TDF use are linked to progressive decline in renal function or other adverse outcomes are needed in Africa.

  14. 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.

  15. Pearling instabilities of membrane tubes with anchored polymers.

    PubMed

    Tsafrir, I; Sagi, D; Arzi, T; Guedeau-Boudeville, M A; Frette, V; Kandel, D; Stavans, J

    2001-02-05

    We have studied the pearling instability induced on hollow tubular lipid vesicles by hydrophilic polymers with hydrophobic side groups along the backbone. The results show that the polymer concentration is coupled to local membrane curvature. The relaxation of a pearled tube is characterized by two different well-separated time scales, indicating two physical mechanisms. We present a model, which explains the observed phenomena and predicts polymer segregation according to local membrane curvature at late stages.

  16. Deletion of the Chloride Transporter Slc26a7 Causes Distal Renal Tubular Acidosis and Impairs Gastric Acid Secretion*

    PubMed Central

    Xu, Jie; Song, Penghong; Nakamura, Suguru; Miller, Marian; Barone, Sharon; Alper, Seth L.; Riederer, Brigitte; Bonhagen, Janina; Arend, Lois J.; Amlal, Hassane; Seidler, Ursula; Soleimani, Manoocher

    2009-01-01

    SLC26A7 (human)/Slc26a7 (mouse) is a recently identified chloride-base exchanger and/or chloride transporter that is expressed on the basolateral membrane of acid-secreting cells in the renal outer medullary collecting duct (OMCD) and in gastric parietal cells. Here, we show that mice with genetic deletion of Slc26a7 expression develop distal renal tubular acidosis, as manifested by metabolic acidosis and alkaline urine pH. In the kidney, basolateral Cl−/HCO3− exchange activity in acid-secreting intercalated cells in the OMCD was significantly decreased in hypertonic medium (a normal milieu for the medulla) but was reduced only mildly in isotonic medium. Changing from a hypertonic to isotonic medium (relative hypotonicity) decreased the membrane abundance of Slc26a7 in kidney cells in vivo and in vitro. In the stomach, stimulated acid secretion was significantly impaired in isolated gastric mucosa and in the intact organ. We propose that SLC26A7 dysfunction should be investigated as a potential cause of unexplained distal renal tubular acidosis or decreased gastric acid secretion in humans. PMID:19723628

  17. Evaluation of water and electrolyte transport of tubular epithelial cells under osmotic and hydraulic pressure for development of bioartificial tubules.

    PubMed

    Terashima, M; Fujita, Y; Sugano, K; Asano, M; Kagiwada, N; Sheng, Y; Nakamura, S; Hasegawa, A; Kakuta, T; Saito, A

    2001-03-01

    Our aim was to develop bioartificial tubules using tubular epithelial cells and artificial membranes and evaluate the function of water and electrolyte transport by various tubular epithelial cells. The cells were cultivated onto extracellular matrix (ProNectin F) coating polycarbonate membrane. Water transport from the apical to the basolateral site of cells was examined using a modified Ussing chamber module. Water transport under colloidal osmotic pressure on the apical site and hydraulic pressure on the basolateral site were higher in JTC-12, LLC-PK1 cells than in MDCK cells. Water transport under osmotic plus hydraulic pressure was highest in LLC-PK1 cells. We made bioartificial tubules using LLC-PK1 cells and polysulfone hollow fiber cartridges. Water and Na ion transport function was high, and BUN and creatinine passage was recognized in these bioartificial tubules. BUN and creatinine concentrations of reabsorption fluid in these bioartificial tubules were significantly lower than those concentrations of control media and of noncell attached polysulfone hollow fiber cartridges. Though LLC-PK1 cells were more preferable cells for the use of bioartificial tubules in terms of water and electrolyte transport, the passage of BUN and creatinine was not appropriate for clinical use. To select more preferable cells for bioartificial tubules which transport water and electrolytes and do not induce passage of uremic toxins is necessary.

  18. 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.

  19. 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.

  20. 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.

  1. Endocytic sorting and recycling require membrane phosphatidylserine asymmetry maintained by TAT-1/CHAT-1.

    PubMed

    Chen, Baohui; Jiang, Yue; Zeng, Sheng; Yan, Jiacong; Li, Xin; Zhang, Yan; Zou, Wei; Wang, Xiaochen

    2010-12-09

    Endocytic sorting is achieved through the formation of morphologically and functionally distinct sub-domains within early endosomes. Cargoes destined for recycling are sorted to and transported through newly-formed tubular membranes, but the processes that regulate membrane tubulation are poorly understood. Here, we identified a novel Caenorhabditis elegans Cdc50 family protein, CHAT-1, which acts as the chaperone of the TAT-1 P4-ATPase to regulate membrane phosphatidylserine (PS) asymmetry and endocytic transport. In chat-1 and tat-1 mutants, the endocytic sorting process is disrupted, leading to defects in both cargo recycling and degradation. TAT-1 and CHAT-1 colocalize to the tubular domain of the early endosome, the tubular endocytic recycling compartment (ERC), and the recycling endosome where PS is enriched on the cytosolic surface. Loss of tat-1 and chat-1 function disrupts membrane PS asymmetry and abrogates the tubular membrane structure. Our data suggest that CHAT-1 and TAT-1 maintain membrane phosphatidylserine asymmetry, thus promoting membrane tubulation and regulating endocytic sorting and recycling.

  2. Endocytic Sorting and Recycling Require Membrane Phosphatidylserine Asymmetry Maintained by TAT-1/CHAT-1

    PubMed Central

    Chen, Baohui; Jiang, Yue; Zeng, Sheng; Yan, Jiacong; Li, Xin; Zhang, Yan; Zou, Wei; Wang, Xiaochen

    2010-01-01

    Endocytic sorting is achieved through the formation of morphologically and functionally distinct sub-domains within early endosomes. Cargoes destined for recycling are sorted to and transported through newly-formed tubular membranes, but the processes that regulate membrane tubulation are poorly understood. Here, we identified a novel Caenorhabditis elegans Cdc50 family protein, CHAT-1, which acts as the chaperone of the TAT-1 P4-ATPase to regulate membrane phosphatidylserine (PS) asymmetry and endocytic transport. In chat-1 and tat-1 mutants, the endocytic sorting process is disrupted, leading to defects in both cargo recycling and degradation. TAT-1 and CHAT-1 colocalize to the tubular domain of the early endosome, the tubular endocytic recycling compartment (ERC), and the recycling endosome where PS is enriched on the cytosolic surface. Loss of tat-1 and chat-1 function disrupts membrane PS asymmetry and abrogates the tubular membrane structure. Our data suggest that CHAT-1 and TAT-1 maintain membrane phosphatidylserine asymmetry, thus promoting membrane tubulation and regulating endocytic sorting and recycling. PMID:21170358

  3. Kinetics of carbendazim degradation in a horizontal tubular biofilm reactor.

    PubMed

    Alvarado-Gutiérrez, María Luisa; Ruiz-Ordaz, Nora; Galíndez-Mayer, Juvencio; Santoyo-Tepole, Fortunata; Curiel-Quesada, Everardo; García-Mena, Jaime; Ahuatzi-Chacón, Deifilia

    2016-12-22

    The fungicide carbendazim is an ecotoxic agent affecting aquatic biota. Due to its suspected hormone-disrupting effects, it is considered a "priority hazard substance" by the Water Framework Directive of the European Commission, and its degradation is of major concern. In this work, a horizontal tubular biofilm reactor (HTBR) operating in plug-flow regime was used to study the kinetics of carbendazim removal by an acclimated microbial consortium. The reactor was operated in steady state continuous culture at eight different carbendazim loading rates. The concentrations of the fungicide were determined at several distances of the HTBR. At the loading rates tested, the highest instantaneous removal rates were observed in the first section of the tubular biofilm reactor. No evidence of inhibition of the catabolic activity of the microbial community was found. Strains of the genera Flectobacillus, Klebsiella, Stenotrophomonas, and Flavobacterium were identified in the biofilm; the last three degrade carbendazim in axenic culture.

  4. A new tubular hot-wire CVD for diamond coating

    NASA Astrophysics Data System (ADS)

    Motahari, Hamid; Bellah, Samad Moemen; Malekfar, Rasoul

    2017-06-01

    A new tubular hot-wire chemical vapor deposition (HWCVD) system using a tubular quartz vacuum chamber has been fabricated. The filaments in this system can heat the substrate and act as a gas activator and thermally activator for gas species at the same time. The nano- and microcrystalline diamond coatings on the surface of steel AISI 316 substrates have been grown. To assess the results, SEM and FESEM images and Raman spectroscopy investigations have been applied. The results reveal that micro- and nanocrystalline diamond structures have been formed in the coatings, but the disordered diamond and some non-diamond phases, such as graphitic carbons, are also present in the coating layers. The analytical measurements show the growth of diamond films with well-faceted crystals in (111) direction. However, intrinsic stress, secondary nucleation, and poor adhesion are the main issues of future research for this new designed HWCVD.

  5. An early Cambrian agglutinated tubular lophophorate with brachiopod characters

    NASA Astrophysics Data System (ADS)

    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.

    2014-05-01

    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.

  6. 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.

  7. 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.

  8. Numerical simulation of premixed H2-air cellular tubular flames

    NASA Astrophysics Data System (ADS)

    Hall, Carl Alan; Wendell Pitz, Robert

    2016-03-01

    The detailed flame structure of laminar premixed cellular flames in the tubular domain is simulated in 2D using a fully-implicit primitive variable finite difference formulation that includes multicomponent transport and detailed chemical kinetics. Numerical results for H2/air flames are presented and compared against spatially resolved experimental measurements of temperature and chemical species including atomic H and OH. The experimental results compare well for flame structure and cell number, despite the numerical model under-predicting the peak temperature by 200 K. Numerical experiments were performed to assess the ability for cellular tubular flames to impact experimental and numerical investigations of practical flames. The cellular flame structure is found to provide a highly sensitive geometry that is useful for validating diffusive transport modelling approximations. This capability is exemplified through the development of a simple and accurate approximation for thermal diffusion (i.e. the Soret effect) that is suitable for practical combustion codes.

  9. Hypophosphatemic rickets due to perturbations in renal tubular function.

    PubMed

    Penido, Maria Goretti M G; Alon, Uri S

    2014-03-01

    The common denominator for all types of rickets is hypophosphatemia, leading to inadequate supply of the mineral to the growing bone. Hypophosphatemia can result from insufficient uptake of the mineral from the gut or its disproportionate losses in the kidney, the latter being caused by either tubular abnormalities per se or the effect on the tubule of circulating factors like fibroblast growth factor-23 and parathyroid hormone (PTH). High serum levels of the latter result in most cases from abnormalities in vitamin D metabolism which lead to decreased calcium absorption in the gut and hypocalcemia, triggering PTH secretion. Rickets is a disorder of the growth plate and hence pediatric by definition. However, it is important to recognize that the effect of hypophosphatemia on other parts of the skeleton results in osteomalacia in both children and adults. This review addresses the etiology, pathophysiologic mechanisms, clinical manifestations and treatment of entities associated with hypophosphatemic rickets due to perturbations in renal tubular function.

  10. 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

  11. 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.

  12. 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.

  13. Role of mitochondrial permeability transition in human renal tubular epithelial cell death induced by aristolochic acid

    SciTech Connect

    Qi Xinming; Cai Yan; Gong Likun; Liu Linlin; Chen Fangping; Xiao Ying; Wu Xiongfei; Li Yan; Xue Xiang |; Ren Jin . E-mail: cdser_simm@mail.shcnc.ac.cn

    2007-07-01

    Aristolochic acid (AA), a natural nephrotoxin and carcinogen, can induce a progressive tubulointerstitial nephropathy. However, the mechanism by which AA causes renal injury remains largely unknown. Here we reported that the mitochondrial permeability transition (MPT) plays an important role in the renal injury induced by aristolochic acid I (AAI). We found that in the presence of Ca{sup 2+}, AAI caused mitochondrial swelling, leakage of Ca{sup 2+}, membrane depolarization, and release of cytochrome c in isolated kidney mitochondria. These alterations were suppressed by cyclosporin A (CsA), an agent known to inhibit MPT. Culture of HK-2 cell, a human renal tubular epithelial cell line for 24 h with AAI caused a decrease in cellular ATP, mitochondrial membrane depolarization, cytochrome c release, and increase of caspase 3 activity. These toxic effects of AAI were attenuated by CsA and bongkrekic acid (BA), another specific MPT inhibitor. Furthermore, AAI greatly inhibited the activity of mitochondrial adenine nucleotide translocator (ANT) in isolated mitochondria. We suggested that ANT may mediate, at least in part, the AAI-induced MPT. Taken together, these results suggested that MPT plays a critical role in the pathogenesis of HK-2 cell injury induced by AAI and implied that MPT might contribute to human nephrotoxicity of aristolochic acid.

  14. Diacylglycerol kinase α regulates tubular recycling endosome biogenesis and major histocompatibility complex class I recycling.

    PubMed

    Xie, Shuwei; Naslavsky, Naava; Caplan, Steve

    2014-11-14

    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.

  15. Influence of iodine in excess on seminiferous tubular structure and epididymal sperm character in male rats.

    PubMed

    Chandra, Amar K; Chakraborty, Arijit

    2017-06-01

    Excess iodine induced public health problems are now emerging in many iodine sufficient regions for indiscriminate intake of iodine through various iodized products. It has been reported that excess iodine can disrupt overall male reproductive physiology by generating oxidative stress in the testis. However, information on the possible effect of iodine in excess on spermatozoa found less. In the present investigation flow cytometric techniques and scanning electron microscopy (SEM) have been used to study the spermatozoal functional as well as structural status under the influence of excess iodine; generation of ROS in the spermatozoa as evident by DCFDA, altered acrosomal integrity as observed by fluorescence lectin staining method and depolarized mitochondrial membrane potential (ΔΨm ) noticed by JC-1 staining. Ultrastructure of seminiferous tubule after excess iodine exposure indicated severe deterioration of seminiferous tubular surface architecture. Significant increase in spermatozoal DNA fragmentation and apoptotic sperms were found by acridine orange and Annexin V, respectively, however the plasma membrane integrity/viability was decreased as evident by propidium iodide staining in various incremental doses and durations under iodine excess. The study reveals that excess iodine could cause apoptosis of spermatozoal cells by inducing ROS that ultimately affects male fertility potential. © 2017 Wiley Periodicals, Inc.

  16. 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

  17. 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.

  18. Isolation of mitochondria with cubic membrane morphology reveals specific ionic requirements for the preservation of membrane structure.

    PubMed

    Chong, Ketpin; Tan, Olivia Li Ling; Almsherqi, Zakaria A; Lin, Qingsong; Kohlwein, Sepp D; Deng, Yuru

    2015-03-01

    Biological membranes with cubic symmetry are a hallmark of virus-infected or diseased cells. The mechanisms of formation and specific cellular functions of cubic membranes, however, are unclear. The best-documented cubic membrane formation occurs in the free-living giant amoeba Chaos carolinense. In that system, mitochondrial inner membranes undergo a reversible structural change from tubular to cubic membrane organization upon starvation of the organism. As a prerequisite to further analyze the structural and functional features of cubic membranes, we adapted protocols for the isolation of mitochondria from starved amoeba and have identified buffer conditions that preserve cubic membrane morphology in vitro. The requirement for high concentration of ion-chelating agents in the isolation media supports the importance of a balanced ion milieu in establishing and maintaining cubic membranes in vivo.

  19. Connexin 30 deficiency impairs renal tubular ATP release and pressure natriuresis.

    PubMed

    Sipos, Arnold; Vargas, Sarah L; Toma, Ildikó; Hanner, Fiona; Willecke, Klaus; Peti-Peterdi, János

    2009-08-01

    In the renal tubule, ATP is an important regulator of salt and water reabsorption, but the mechanism of ATP release is unknown. Several connexin (Cx) isoforms form mechanosensitive, ATP-permeable hemichannels. We localized Cx30 to the nonjunctional apical membrane of cells in the distal nephron and tested whether Cx30 participates in physiologically important release of ATP. We dissected, partially split open, and microperfused cortical collecting ducts from wild-type and Cx30-deficient mice in vitro. We used PC12 cells as ATP biosensors by loading them with Fluo-4/Fura Red to measure cytosolic calcium and positioning them in direct contact with the apical surface of either intercalated or principal cells. ATP biosensor responses, triggered by increased tubular flow or by bath hypotonicity, were approximately three-fold greater when positioned next to intercalated cells than next to principal cells. In addition, these responses did not occur in preparations from Cx30-deficient mice or with purinergic receptor blockade. After inducing step increases in mean arterial pressure by ligating the distal aorta followed by the mesenteric and celiac arteries, urine output increased 4.2-fold in wild-type mice compared with 2.6-fold in Cx30-deficient mice, and urinary Na(+) excretion increased 5.2-fold in wild-type mice compared with 2.8-fold in Cx30-deficient mice. Furthermore, Cx30-deficient mice developed endothelial sodium channel-dependent, salt-sensitive elevations in mean arterial pressure. Taken together, we suggest that mechanosensitive Cx30 hemichannels have an integral role in pressure natriuresis by releasing ATP into the tubular fluid, which inhibits salt and water reabsorption.

  20. Connexin 30 Deficiency Impairs Renal Tubular ATP Release and Pressure Natriuresis

    PubMed Central

    Sipos, Arnold; Vargas, Sarah L.; Toma, Ildikó; Hanner, Fiona; Willecke, Klaus

    2009-01-01

    In the renal tubule, ATP is an important regulator of salt and water reabsorption, but the mechanism of ATP release is unknown. Several connexin (Cx) isoforms form mechanosensitive, ATP-permeable hemichannels. We localized Cx30 to the nonjunctional apical membrane of cells in the distal nephron and tested whether Cx30 participates in physiologically important release of ATP. We dissected, partially split open, and microperfused cortical collecting ducts from wild-type and Cx30-deficient mice in vitro. We used PC12 cells as ATP biosensors by loading them with Fluo-4/Fura Red to measure cytosolic calcium and positioning them in direct contact with the apical surface of either intercalated or principal cells. ATP biosensor responses, triggered by increased tubular flow or by bath hypotonicity, were approximately three-fold greater when positioned next to intercalated cells than next to principal cells. In addition, these responses did not occur in preparations from Cx30-deficient mice or with purinergic receptor blockade. After inducing step increases in mean arterial pressure by ligating the distal aorta followed by the mesenteric and celiac arteries, urine output increased 4.2-fold in wild-type mice compared with 2.6-fold in Cx30-deficient mice, and urinary Na+ excretion increased 5.2-fold in wild-type mice compared with 2.8-fold in Cx30-deficient mice. Furthermore, Cx30-deficient mice developed endothelial sodium channel–dependent, salt-sensitive elevations in mean arterial pressure. Taken together, we suggest that mechanosensitive Cx30 hemichannels have an integral role in pressure natriuresis by releasing ATP into the tubular fluid, which inhibits salt and water reabsorption. PMID:19478095

  1. Potent activation of multiple signalling pathways by C-peptide in opossum kidney proximal tubular cells.

    PubMed

    Al-Rasheed, N M; Meakin, F; Royal, E L; Lewington, A J; Brown, J; Willars, G B; Brunskill, N J

    2004-06-01

    Proinsulin C-peptide is generally believed to be inert without any appreciable biological functions. However, it has been shown to modulate a variety of cellular processes important in the pathophysiology of diabetic complications. We therefore investigated the ability of C-peptide to stimulate intracellular signalling pathways in kidney proximal tubular cells, the altered activation of which may possibly be related to the development of diabetic nephropathy. Extracellular signal-regulated kinase (ERK) and Akt phosphorylation were evaluated by western blotting. ERK activity was measured by in vitro kinase assay. Intracellular Ca(2+) was evaluated by confocal imaging. The membrane and cytosol-associated fractions of protein kinase C (PKC) isoforms were evaluated by western blotting. Proliferation was assessed by thymidine incorporation assay. Using the opossum proximal tubular kidney cell line as a model, we demonstrated that at high picomolar to low nanomolar concentrations, C-peptide stimulates extracellular signal-regulated mitogen-activated kinase (3.3+/-0.1-fold over basal at 3 minutes) and phosphatidylinositol 3-kinase (4.1+/-0.05-fold over basal at 5 minutes). ERK activation was attenuated by pre-treatment with a PKC inhibitor and abolished by pertussis toxin. Elevations of intracellular [Ca(2+)] are seen in response to 5 nmol/l C-peptide with consequent activation of PKC-alpha. Pre-treatment with pertussis toxin abolished PKC-alpha. C-peptide is also a functional mitogen in this cell type, stimulating significantly increased cell proliferation. Proliferation was attenuated by wortmannin and pertussis toxin pre-treatments. None of these effects is reproduced by scrambled C-peptide. This study provides evidence that C-peptide, within physiological concentration ranges, stimulates many signalling pathways in opossum kidney cells.

  2. Nebivolol Attenuates Redox-Sensitive Glomerular and Tubular Mediated Proteinuria in Obese Rats

    PubMed Central

    Habibi, Javad; Hayden, Melvin R.; Sowers, James R.; Pulakat, Lakshmi; Tilmon, Roger D.; Manrique, Camila; Lastra, Guido; DeMarco, Vincent G.

    2011-01-01

    Obesity and insulin resistance-related proteinuria is associated with oxidative stress and impaired tissue bioavailable nitric oxide. Recent data suggest that nicotinamide adenine dinucleotide phosphate oxidase-mediated oxidative injury to the proximal tubule, like that seen in the glomerulus, contributes to proteinuria in insulin-resistant states. The vasodilator β-blocker nebivolol reduces nicotinamide adenine dinucleotide phosphate oxidase activity, increases bioavailable nitric oxide, and improves insulin sensitivity. To test the hypothesis that a treatment strategy that reduces oxidative stress and attenuates obesity-associated increases in glomerular and proximal tubule derived protein, we treated young Zucker obese (ZO) and age-matched Zucker lean male rats with nebivolol (10 mg · kg−1 · d−1) for 21 d. Compared with Zucker lean, ZO controls exhibited increased proteinuria and γ-glutamyl transpeptidase, reductions in systemic insulin sensitivity in association with increased renal renin, (pro)renin receptor, angiotensin II type 1 receptor, and mineralocorticoid receptor immunostaining, oxidative stress, and glomerular tubular structural abnormalities that were substantially improved with in vivo nebivolol treatment. Nebivolol treatment also led to improvements in glomerular podocyte foot-process effacement and improvement in podocyte-specific proteins (nephrin and synaptopodin) as well as proximal tubule-specific proteins (megalin and lysosomal-associated membrane protein-2) and proximal tubule ultrastructural remodeling in the ZO kidney. Our findings support the notion that obesity and insulin resistance lead to increased glomerulotubular oxidative stress and resultant glomerular and tubular sources of excess urine protein. Furthermore, the results of this study suggest the beneficial effect of nebivolol on proteinuria was derived from improvements in weight and insulin sensitivity and reductions in renal oxidative stress in a state of obesity and

  3. The small GTPase Cdc42 is necessary for primary ciliogenesis in renal tubular epithelial cells.

    PubMed

    Zuo, Xiaofeng; Fogelgren, Ben; Lipschutz, Joshua H

    2011-06-24

    Primary cilia are found on many epithelial cell types, including renal tubular epithelial cells, where they participate in flow sensing. Disruption of cilia function has been linked to the pathogenesis of polycystic kidney disease. We demonstrated previously that the exocyst, a highly conserved eight-protein membrane trafficking complex, localizes to primary cilia of renal tubular epithelial cells, is required for ciliogenesis, biochemically and genetically interacts with polycystin-2 (the protein product of the polycystic kidney disease 2 gene), and, when disrupted, results in MAPK pathway activation both in vitro and in vivo. The small GTPase Cdc42 is a candidate for regulation of the exocyst at the primary cilium. Here, we demonstrate that Cdc42 biochemically interacts with Sec10, a crucial component of the exocyst complex, and that Cdc42 colocalizes with Sec10 at the primary cilium. Expression of dominant negative Cdc42 and shRNA-mediated knockdown of both Cdc42 and Tuba, a Cdc42 guanine nucleotide exchange factor, inhibit ciliogenesis in Madin-Darby canine kidney cells. Furthermore, exocyst Sec8 and polycystin-2 no longer localize to primary cilia or the ciliary region following Cdc42 and Tuba knockdown. We also show that Sec10 directly interacts with Par6, a member of the Par complex that itself directly interacts with Cdc42. Finally, we show that Cdc42 knockdown results in activation of the MAPK pathway, something observed in cells with dysfunctional primary cilia. These data support a model in which Cdc42 localizes the exocyst to the primary cilium, whereupon the exocyst then targets and docks vesicles carrying proteins necessary for ciliogenesis.

  4. The Small GTPase Cdc42 Is Necessary for Primary Ciliogenesis in Renal Tubular Epithelial Cells*

    PubMed Central

    Zuo, Xiaofeng; Fogelgren, Ben; Lipschutz, Joshua H.

    2011-01-01

    Primary cilia are found on many epithelial cell types, including renal tubular epithelial cells, where they participate in flow sensing. Disruption of cilia function has been linked to the pathogenesis of polycystic kidney disease. We demonstrated previously that the exocyst, a highly conserved eight-protein membrane trafficking complex, localizes to primary cilia of renal tubular epithelial cells, is required for ciliogenesis, biochemically and genetically interacts with polycystin-2 (the protein product of the polycystic kidney disease 2 gene), and, when disrupted, results in MAPK pathway activation both in vitro and in vivo. The small GTPase Cdc42 is a candidate for regulation of the exocyst at the primary cilium. Here, we demonstrate that Cdc42 biochemically interacts with Sec10, a crucial component of the exocyst complex, and that Cdc42 colocalizes with Sec10 at the primary cilium. Expression of dominant negative Cdc42 and shRNA-mediated knockdown of both Cdc42 and Tuba, a Cdc42 guanine nucleotide exchange factor, inhibit ciliogenesis in Madin-Darby canine kidney cells. Furthermore, exocyst Sec8 and polycystin-2 no longer localize to primary cilia or the ciliary region following Cdc42 and Tuba knockdown. We also show that Sec10 directly interacts with Par6, a member of the Par complex that itself directly interacts with Cdc42. Finally, we show that Cdc42 knockdown results in activation of the MAPK pathway, something observed in cells with dysfunctional primary cilia. These data support a model in which Cdc42 localizes the exocyst to the primary cilium, whereupon the exocyst then targets and docks vesicles carrying proteins necessary for ciliogenesis. PMID:21543338

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

    PubMed

    Guo, Chin-Lin

    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.

  6. The hybrid ring tubular external fixator: a biomechanical study.

    PubMed

    Stein, H; Mosheiff, R; Baumgart, F; Frigg, R; Perren, S M; Cordey, J

    1997-06-01

    OBJECTIVE: To measure and compare the mechanical properties in bending of the four-ring, and three-ring/one-tube hybrid external fixation frames. DESIGN. IN VITRO: measurements of the mechanical behaviour of ring and ring-tubular external fixation frames. In the latter, one ring of the full circular frame was replaced by one tube and Schanz screws. BACKGROUND: The mechanical properties of the classical Ilizarov four-ring external fixation frames has been compared to those of other external fixation frames by various authors. However, in clinical practice the hybrid fixation frame is being used with increasing frequency. Therefore the mechanical properties of the latter are of immediate interest and clinical value. METHODS: On explanted sheep tibiae with single and double osteotomies, frame stiffness in the four-point bending mode was measured at different K-wire tensions, comparing the values obtained from four-ring frames, to those of three-ring-tubular hybrid frames. These measurements were made under conditions of (a) bone distraction (BD), and (b) segment transport (ST), both at the initial and final stages of this procedure. RESULTS: In circular frames, frame stiffness in bending for increasing K-wire tension showed a Gaussian distribution both in distraction and post-ST with an optimum at 1000 N. In ring tubular hybrid frames, however, frame stiffness showed a more linear relationship to K-wire tension. CONCLUSIONS: In the four-ring Ilizarov external fixation frame, the exchange of one ring with one tube and one Schanz screw both reduced frame stiffness in bending and converted to linear its relationship to K-wire tension. RELEVANCE: Under clinical conditions, the use of a similar ring tubular hybrid external fixator allows the adjustment of frame stiffness in a simple and practical way. This is not the case with the original ring fixation frame.

  7. 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.

  8. 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

  9. Angiotensin II induces apoptosis in renal proximal tubular cells.

    PubMed

    Bhaskaran, Madhu; Reddy, Krishna; Radhakrishanan, Neetu; Franki, Nicholas; Ding, Guohua; Singhal, Pravin C

    2003-05-01

    ANG II has been demonstrated to play a role in the progression of tubulointerstial injury. We studied the direct effect of ANG II on apoptosis of cultured rat renal proximal tubular epithelial cells (RPTECs). ANG II promoted RPTEC apoptosis in a dose- and time-dependent manner. This effect of ANG II was attenuated by anti-transforming growth factor (TGF)-beta antibody. Moreover, TGF-beta triggered RPTEC apoptosis in a dose-dependent manner. ANG II also enhanced RPTEC expression of Fas and Fas ligand (FasL); furthermore, anti-FasL antibody attenuated ANG II-induced RPTEC apoptosis. In addition, ANG II increased RPTEC expression of Bax, a cell death protein. Both ANG II type 1 (AT(1)) and type 2 (AT(2)) receptor blockers inhibited ANG II-induced RPTEC apoptosis. SB-202190, an inhibitor of p38 MAPK phosphorylation, and caspase-3 inhibitor also attenuated ANG II-induced RPTEC apoptosis. ANG II enhanced RPTEC heme oxygenase (HO)-1 expression. Interestingly, pretreatment with hemin as well as curcumin (inducers of HO-1) inhibited the ANG II-induced tubular cell apoptosis; conversely, pretreatment with zinc protoporphyrin, an inhibitor of HO-1 expression, promoted the effect of ANG II. These results suggest that ANG II-induced apoptosis is mediated via both AT(1) and AT(2) receptors through the generation of TGF-beta, followed by the transcription of cell death genes such as Fas, FasL, and Bax. Modulation of tubular cell expression of HO-1 has an inverse relationship with the ANG II-induced tubular cell apoptosis.

  10. 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

  11. Solar energy utilisation and evacuated tubular solar collectors

    NASA Astrophysics Data System (ADS)

    Parand, Foroutan

    Four types of evacuated tubular solar collectors have been constructed and their performance evaluated. The characteristics of the collectors are then compared and their design strengths assessed. One of the designs, a flat absorber with a single glass cover using glass to metal seals was found to have the best performance among the four designs which included a dewar vessel type collector, a heat pipe collector and a black liquid collector with an optical efficiency of 87.7 pct. and an overall heat loss coefficient of 12.3 Wm(exp -2)/C. The performance of the dewar vessel type and black liquid collectors was found to be comparable to the glass to metal seal collector. A detailed analysis of the optical and thermal processes in evacuated tubular collectors was made. On the basis of this analysis a computer simulation model using a finite difference technique has been developed to predict the performance of evacuated tubular collectors. The computer simulation results are then compared with the test results. For the majority of the tests the discrepancy between the simulation and the test results was within the error band of the test results (maximum 12 pct.). For the published test results the maximum discrepancy for operating temperature below 100 C was found to be 6 pct. The computer simulation model was compared with other published models and its advantages and disadvantages discussed. In some analytical and semi-analytical simulation models the energy absorbed by the glass cover and the heat loss from joints and supports has to be ignored. The present model has none of these deficiencies and more complex designs can be simulated. The developed computer simulation program might be used as an aid in the design of evacuated tubular collectors. Using the computer simulation, a parametric study of the three commmercially available collectors was made. The results are discussed and the areas of improvement are identified.

  12. Plastic deformation of tubular crystals by dislocation glide.

    PubMed

    Beller, Daniel A; Nelson, David R

    2016-09-01

    Tubular crystals, two-dimensional lattices wrapped into cylindrical topologies, arise in many contexts, including botany and biofilaments, and in physical systems such as carbon nanotubes. The geometrical principles of botanical phyllotaxis, describing the spiral packings on cylinders commonly found in nature, have found application in all these systems. Several recent studies have examined defects in tubular crystals associated with crystalline packings that must accommodate a fixed tube radius. Here we study the mechanics of tubular crystals with variable tube radius, with dislocations interposed between regions of different phyllotactic packings. Unbinding and separation of dislocation pairs with equal and opposite Burgers vectors allow the growth of one phyllotactic domain at the expense of another. In particular, glide separation of dislocations offers a low-energy mode for plastic deformations of solid tubes in response to external stresses, reconfiguring the lattice step by step. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, the mechanics of dislocation glide. We also discuss how a sufficiently strong bending rigidity can alter or arrest the deformations of tubes with small radii.

  13. Vascular versus tubular renin: role in kidney development

    PubMed Central

    Nagalakshmi, Vidya K.; Li, Minghong; Sigmund, Curt D.; Gomez, R. Ariel

    2015-01-01

    Renin, the key regulated enzyme of the renin-angiotensin system regulates blood pressure, fluid-electrolyte homeostasis, and renal morphogenesis. Whole body deletion of the renin gene results in severe morphological and functional derangements, including thickening of renal arterioles, hydronephrosis, and inability to concentrate the urine. Because renin is found in vascular and tubular cells, it has been impossible to discern the relative contribution of tubular versus vascular renin to such a complex phenotype. Therefore, we deleted renin independently in the vascular and tubular compartments by crossing Ren1c fl/fl mice to Foxd1-cre and Hoxb7-cre mice, respectively. Deletion of renin in the vasculature resulted in neonatal mortality that could be rescued with daily injections of saline. The kidneys of surviving mice showed the absence of renin, hypertrophic arteries, hydronephrosis, and negligible levels of plasma renin. In contrast, lack of renin in the collecting ducts did not affect kidney morphology, intra-renal renin, or circulating renin in basal conditions or in response to a homeostatic stress, such as sodium depletion. We conclude that renin generated in the renal vasculature is fundamental for the development and integrity of the kidney, whereas renin in the collecting ducts is dispensable for normal kidney development and cannot compensate for the lack of renin in the vascular compartment. Further, the main source of circulating renin is the kidney vasculature. PMID:26246508

  14. 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.

  15. Hierarchically designed electrospun tubular scaffolds for cardiovascular applications.

    PubMed

    Shalumon, K T; Sreerekha, P R; Sathish, D; Tamura, H; Nair, S V; Chennazhi, K P; Jayakumar, R

    2011-10-01

    Hierarchically designed tubular scaffolds with bi-layer and multi-layer structures are expected to mimic native vessels in its structural geometry. A new approach for the fabrication of hierarchically designed tubular scaffold with suitable morphology was introduced through electrospinning technique. Among these scaffolds, bi-layer scaffold had a single inner and outer layer whereas multilayer scaffold had more number of inner layers. The inner layer/layers of the scaffolds were made up of aligned poly (lactic acid) (PLA) fibers for EC adhesion where as outer layers were composed of random fibers of poly (caprolactone) (PCL) and PLA providing larger pores for SMC penetration. The fabricated scaffolds were characterized by FTIR spectroscopy and Differential Thermal Analysis (DTA) and examined by evaluating cellular interactions. Human Umbilical Vein Endothelial Cells (HUVECs) seeded on aligned PLA fibers showed enhanced cellular orientation and cytoskeletal organization. In addition, the PCL-PLA composite random fibers supported SMC adhesion and proliferation sufficiently. The functionality of the endothelial cells grown on the PLA-aligned scaffold was also found to be satisfactory. Lining the constructs with a luminal monolayer of well-organized ECs along with homogenously distributed SMCs surrounding them might result in vascular conduits suitable for in vivo applications. Since this hierarchically designed tubular scaffold closely mimics the morphology of native vessel, this could be a better candidate for vascular tissue engineering.

  16. Plastic deformation of tubular crystals by dislocation glide

    NASA Astrophysics Data System (ADS)

    Beller, Daniel A.; Nelson, David R.

    2016-09-01

    Tubular crystals, two-dimensional lattices wrapped into cylindrical topologies, arise in many contexts, including botany and biofilaments, and in physical systems such as carbon nanotubes. The geometrical principles of botanical phyllotaxis, describing the spiral packings on cylinders commonly found in nature, have found application in all these systems. Several recent studies have examined defects in tubular crystals associated with crystalline packings that must accommodate a fixed tube radius. Here we study the mechanics of tubular crystals with variable tube radius, with dislocations interposed between regions of different phyllotactic packings. Unbinding and separation of dislocation pairs with equal and opposite Burgers vectors allow the growth of one phyllotactic domain at the expense of another. In particular, glide separation of dislocations offers a low-energy mode for plastic deformations of solid tubes in response to external stresses, reconfiguring the lattice step by step. Through theory and simulation, we examine how the tube's radius and helicity affects, and is in turn altered by, the mechanics of dislocation glide. We also discuss how a sufficiently strong bending rigidity can alter or arrest the deformations of tubes with small radii.

  17. 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.

  18. 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.

  19. Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA.

    PubMed

    San Juan, Aurélie; Ducrocq, Grégory; Hlawaty, Hanna; Bataille, Isabelle; Guénin, Erwann; Letourneur, Didier; Feldman, Laurent J

    2007-12-01

    In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethylamine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies.

  20. 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.

  1. Augmented reality visualization of deformable tubular structures for surgical simulation.

    PubMed

    Ferrari, Vincenzo; Viglialoro, Rosanna Maria; Nicoli, Paola; Cutolo, Fabrizio; Condino, Sara; Carbone, Marina; Siesto, Mentore; Ferrari, Mauro

    2016-06-01

    Surgical simulation based on augmented reality (AR), mixing the benefits of physical and virtual simulation, represents a step forward in surgical training. However, available systems are unable to update the virtual anatomy following deformations impressed on actual anatomy. A proof-of-concept solution is described providing AR visualization of hidden deformable tubular structures using nitinol tubes sensorized with electromagnetic sensors. This system was tested in vitro on a setup comprised of sensorized cystic, left and right hepatic, and proper hepatic arteries. In the trial session, the surgeon deformed the tubular structures with surgical forceps in 10 positions. The mean, standard deviation, and maximum misalignment between virtual and real arteries were 0.35, 0.22, and 0.99 mm, respectively. The alignment accuracy obtained demonstrates the feasibility of the approach, which can be adopted in advanced AR simulations, in particular as an aid to the identification and isolation of tubular structures. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Exciton Level Structure and Dynamics in Tubular Porphyrin Aggregates

    SciTech Connect

    Wan, Yan; Stradomska, Anna; Fong, Sarah; Guo, Zhi; Schaller, Richard D.; Wiederrecht, Gary P; Knoester, Jasper; Huang, Libai

    2014-10-30

    We present an account of the optical properties of the Frenkel excitons in self-assembled porphyrin tubular aggregates that represent an analog to natural photosynthetic antennae. Using a combination of ultrafast optical spectroscopy and stochastic exciton modeling, we address both linear and nonlinear exciton absorption, relaxation pathways, and the role of disorder. The static disorder-dominated absorption and fluorescence line widths show little temperature dependence for the lowest excitons (Q band), which we successfully simulate using a model of exciton scattering on acoustic phonons in the host matrix. Temperature-dependent transient absorption of and fluorescence from the excitons in the tubular aggregates are marked by nonexponential decays with time scales ranging from a few picoseconds to a few nanoseconds, reflecting complex relaxation mechanisms. Combined experimental and theoretical investigations indicate that nonradiative pathways induced by traps and defects dominate the relaxation of excitons in the tubular aggregates. We model the pumpprobe spectra and ascribe the excited-state absorption to transitions from one-exciton states to a manifold of mixed one- and two-exciton states. Our results demonstrate that while the delocalized Frenkel excitons (over 208 (1036) molecules for the optically dominant excitons in the Q (B) band) resulting from strong intermolecular coupling in these aggregates could potentially facilitate efficient energy transfer, fast relaxation due to defects and disorder probably present a major limitation for exciton transport over large distances.

  3. Renal Primary Cilia Lengthen after Acute Tubular Necrosis

    PubMed Central

    Verghese, Elizabeth; Ricardo, Sharon D.; Weidenfeld, Raphael; Zhuang, Junli; Hill, Prudence A.; Langham, Robyn G.

    2009-01-01

    Renal primary cilia are sensory antennas required for the maintenance of normal epithelial differentiation and proliferation in the kidney, but they also have a potential role in epithelial differentiation during renal injury and repair. In mice, tubular damage causes an increase in the length of renal cilia, which may modify their sensory sensitivity during repair. Here, we investigated whether the alteration of renal cilium length during renal injury is clinically relevant. Using biopsies of human renal transplants that suffered acute tubular necrosis during transplantation, we compared the length of renal primary cilia with renal function. Serial biopsies showed that acute tubular necrosis resulted in more than a doubling of cilium length throughout the nephron and collecting duct approximately 1 wk after injury. Allografts displayed a trend toward normalization of cilium length in later biopsies, and this correlated with functional recovery. A mouse model of renal ischemia-reperfusion confirmed the increase and subsequent regression of cilium length during renal repair, displaying complete normalization of cilium length within 6 wk of injury. These findings demonstrate that the length of renal cilia is a clinically relevant indicator of renal injury and repair. PMID:19608704

  4. Creep effect modeling for a core free tubular actuator

    NASA Astrophysics Data System (ADS)

    Sarban, Rahimullah; Oubaek, Jakob; Jones, Richard W.

    2009-03-01

    Of the range of dielectric EAP-based actuators that currently exist those having a cylindrical configuration are perhaps the most important. Up until now the most popular tubular actuator designs have exploited the exceptional pre-strain performance of the acrylics VHB 2910 and VHB 2905. Unfortunately pre-stained acrylic film rolled tubular actuators with a spring core experience problems concerning reliability and life expectancy. Partly because of these problems research is beginning to be directed towards the design, fabrication and characterisation of core free tubular actuators. This work reviews the Voltage-Strain modeling of core free rolled actuators that are constructed using a dielectric electro active polymer film that employs smart electrode technology. Position response tests, whereby a step input of 1500 V was applied to each actuator, confirmed that time dependent strain influences the Voltage-Strain behaviour of the actuators. To represent the time dependent strain behaviour a creep effect model was combined with Pelrine's electromechanical model to provide a more accurate representation of the Voltage-Strain characteristics of the actuators.

  5. Sex Differences in Renal Proximal Tubular Cell Homeostasis.

    PubMed

    Seppi, Thomas; Prajczer, Sinikka; Dörler, Maria-Magdalena; Eiter, Oliver; Hekl, Daniel; Nevinny-Stickel, Meinhard; Skvortsova, Iraida; Gstraunthaler, Gerhard; Lukas, Peter; Lechner, Judith

    2016-10-01

    Studies in human patients and animals have revealed sex-specific differences in susceptibility to renal diseases. Because actions of female sex hormones on normal renal tissue might protect against damage, we searched for potential influences of the female hormone cycle on basic renal functions by studying excretion of urinary marker proteins in healthy human probands. We collected second morning spot urine samples of unmedicated naturally ovulating women, postmenopausal women, and men daily and determined urinary excretion of the renal tubular enzymes fructose-1,6-bisphosphatase and glutathione-S-transferase-α Additionally, we quantified urinary excretion of blood plasma proteins α1-microglobulin, albumin, and IgG. Naturally cycling women showed prominent peaks in the temporal pattern of urinary fructose-1,6-bisphosphatase and glutathione-S-transferase-α release exclusively within 7 days after ovulation or onset of menses. In contrast, postmenopausal women and men showed consistently low levels of urinary fructose-1,6-bisphosphatase excretion over comparable periods. We did not detect changes in urinary α1-microglobulin, albumin, or IgG excretion. Results of this study indicate that proximal tubular tissue architecture, representing a nonreproductive organ-derived epithelium, undergoes periodical adaptations phased by the female reproductive hormone cycle. The temporally delimited higher rate of enzymuria in ovulating women might be a sign of recurring increases of tubular cell turnover that potentially provide enhanced repair capacity and thus, higher resistance to renal damage.

  6. Analysis of constant tissue remodeling in Syrian hamster Harderian gland: intra-tubular and inter-tubular syncytial masses.

    PubMed

    Coto-Montes, Ana; García-Macía, Marina; Caballero, Beatriz; Sierra, Verónica; Rodríguez-Colunga, María J; Reiter, Russel J; Vega-Naredo, Ignacio

    2013-05-01

    The Syrian hamster Harderian gland (HG) has a marked sexual dimorphism and exhibits an extraordinary rate of porphyrinogenesis. The physiological oxidative stress, derived from constant porphyrin production, is so high that the HG needs additional survival autophagic mechanisms to fight against this chronic exposure, provoking the triggering of a holocrine secretion in female glands that forms two types of secretory masses: intra-tubular-syncytial and inter-tubular-syncytial masses. The aim of this work was to study the development of this inter-tubular holocrine secretion. To approach this task, we have considered that the steps developed during the formation of the so-called invasive masses consist of the growth of epithelial cells, cell detachment from the basal lamina and invasion of surrounding tissues. The presence of these masses, particularly in the female HG, are closely linked to sexual dimorphism in redox balance and to alterations in the expression of certain factors such as cytokeratins, P-cadherin, matrix metalloproteinases, cathepsin H, proliferating cell nuclear antigen, p53, CD-31 and vascular endothelial growth factor, which seem to be involved in tissue remodeling. The results document unusual mechanisms of secretion in Syrian hamster HG: an extraordinary system of massive secretion through the conjunctive tissue, disrupting the branched structure of the gland.

  7. Analysis of constant tissue remodeling in Syrian hamster Harderian gland: intra-tubular and inter-tubular syncytial masses

    PubMed Central

    Coto-Montes, Ana; García-Macía, Marina; Caballero, Beatriz; Sierra, Verónica; Rodríguez-Colunga, María J; Reiter, Russel J; Vega-Naredo, Ignacio

    2013-01-01

    The Syrian hamster Harderian gland (HG) has a marked sexual dimorphism and exhibits an extraordinary rate of porphyrinogenesis. The physiological oxidative stress, derived from constant porphyrin production, is so high that the HG needs additional survival autophagic mechanisms to fight against this chronic exposure, provoking the triggering of a holocrine secretion in female glands that forms two types of secretory masses: intra-tubular-syncytial and inter-tubular-syncytial masses. The aim of this work was to study the development of this inter-tubular holocrine secretion. To approach this task, we have considered that the steps developed during the formation of the so-called invasive masses consist of the growth of epithelial cells, cell detachment from the basal lamina and invasion of surrounding tissues. The presence of these masses, particularly in the female HG, are closely linked to sexual dimorphism in redox balance and to alterations in the expression of certain factors such as cytokeratins, P-cadherin, matrix metalloproteinases, cathepsin H, proliferating cell nuclear antigen, p53, CD-31 and vascular endothelial growth factor, which seem to be involved in tissue remodeling. The results document unusual mechanisms of secretion in Syrian hamster HG: an extraordinary system of massive secretion through the conjunctive tissue, disrupting the branched structure of the gland. PMID:23496762

  8. Ultrastructural study of the renal tubular system in acute experimental African swine fever: virus replication in glomerular mesangial cells and in the collecting ducts.

    PubMed

    Gómez-Villamandos, J C; Hervás, J; Méndez, A; Carrasco, L; Villeda, C J; Wilkinson, P J; Sierra, M A

    1995-01-01

    Despite the considerable attention given to kidney lesions in African swine fever (ASF), a number of questions remain to be answered. Structural and ultrastructural examination showed that a highly virulent isolate of ASF virus (Malawi 83) replicated in glomerular mesangial cells and renal collecting duct epithelial cells, with hyperplasia of the latter in infected pigs. Replication in mesangial cells may be due to their contact with the bloodstream, as well as to their phagocytic capacity and high metabolism rate. Virus replication in macrophages and endothelial cells of interstitial capillaries, and the necrosis of these infected cells gave rise to a large number of free virus in interstitial tissue. This, together with the lesser thickness of the basal membrane of collecting ducts in comparison to the rest of the tubular system, probably facilitates ASFV infection of tubular epithelial cells. Virus replication in these cells may account for the presence of virus in the urine of pigs with acute ASF where haematuria is not observed.

  9. The role of cholesterol-sphingomyelin membrane nanodomains in the stability of intercellular membrane nanotubes

    PubMed Central

    Lokar, Maruša; Kabaso, Doron; Resnik, Nataša; Sepčić, Kristina; Kralj-Iglič, Veronika; Veranič, Peter; Zorec, Robert; Iglič, Aleš

    2012-01-01

    Intercellular membrane nanotubes (ICNs) are highly curved tubular structures that connect neighboring cells. The stability of these structures depends on the inner cytoskeleton and the cell membrane composition. Yet, due to the difficulty in the extraction of ICNs, the cell membrane composition remains elusive. In the present study, a raft marker, ostreolysin, revealed the enrichment of cholesterol-sphingomyelin membrane nanodomains along ICNs in a T24 (malignant) urothelial cancer cell line. Cholesterol depletion, due to the addition of methyl-β-cyclodextrin, caused the dispersion of cholesterol-sphingomyelin membrane nanodomains and the retraction of ICNs. The depletion of cholesterol also led to cytoskeleton reorganization and to formation of actin stress fibers. Live cell imaging data revealed the possible functional coupling between the change from polygonal to spherical shape, cell separation, and the disconnection of ICNs. The ICN was modeled as an axisymmetric tubular structure, enabling us to investigate the effects of cholesterol content on the ICN curvature. The removal of cholesterol was predicted to reduce the positive spontaneous curvature of the remaining membrane components, increasing their curvature mismatch with the tube curvature. The mechanisms by which the increased curvature mismatch could contribute to the disconnection of ICNs are discussed. PMID:22605937

  10. Longitudinal and transversal propagation of excitation along the tubular system of rat fast-twitch muscle fibres studied by high speed confocal microscopy.

    PubMed

    Edwards, Joshua N; Cully, Tanya R; Shannon, Thomas R; Stephenson, D George; Launikonis, Bradley S

    2012-02-01

    Mammalian skeletal muscle fibres possess a tubular (t-) system that consists of regularly spaced transverse elements which are also connected in the longitudinal direction. This tubular network provides a pathway for the propagation of action potentials (APs) both radially and longitudinally within the fibre, but little is known about the actual radial and longitudinal AP conduction velocities along the tubular network in mammalian skeletal muscle fibres. The aim of this study was to track AP propagation within the t-system network of fast-twitch rat muscle fibres with high spatio-temporal resolution when the t-system was isolated from the surface membrane. For this we used high speed confocal imaging of AP-induced Ca(2+) release in contraction-suppressed mechanically skinned fast-twitch fibres where the t-system can be electrically excited in the absence of the surface membrane. Supramaximal field pulses normally elicited a synchronous AP-induced release of Ca(2+) along one side of the fibre axis which propagated uniformly across the fibre. In some cases up to 80 or more adjacent transverse tubules failed to be excited by the field pulse, while adjacent areas responded with normal Ca(2+) release. In these cases a continuous front of Ca(2+) release with an angle to the scanning line was observed due to APs propagating longitudinally. From these observations the radial/transversal and longitudinal AP conduction velocities along the tubular network deeper in the fibre under our conditions (19 ± 1°C) ranged between 8 and 11 μm ms(-1) and 5 to 9 μm ms(-1), respectively, using different methods of estimation. The longitudinal propagation of APs appeared to be markedly faster closer to the edge of the fibre, in agreement with the presence of dense longitudinal connections immediately below the surface of the fibre and more sparse connections at deeper planes within the fibre. During long trains of closely spaced field pulses the AP-elicited Ca(2+) releases became non

  11. Computer simulation of inorganic membrane morphology: 2 -- Effect of infiltration at the membrane support interface

    SciTech Connect

    Randon, J.; Julbe, A.; David, P.; Jaafari, K. . Lab. de Physicochimie des Materiaux); Elmaleh, S. . Groupe de Genie des Procedes)

    1993-12-01

    The purpose of this work is to demonstrate, through computer modeling of a ceramic membrane filtration element, that infiltration of a membrane into the ceramic support can have a drastic effect on the porosity at the interface and hence on the hydraulic resistance of the filtration element. A computer model using round spheres has been developed, allowing a realistic picture of the support (infiltrated or not) and of the membrane on top of it. This model allows a determination of the porosity in the support and at the membrane/support interface; it shows the effect of infiltration on the porosity. Experimentally, infiltrated and noninfiltrated TiO[sub 2] membranes have been prepared on tubular ceramic supports and their filtration performances have been compared. The results reveal that in order to increase the permeability of filtration elements, their preparation must limit the size of infiltrated zones.

  12. Bioinspired coupled helical coils for soft tissue engineering of tubular structures - Improved mechanical behavior of tubular collagen type I templates.

    PubMed

    Janke, H P; Bohlin, J; Lomme, R M L M; Mihaila, S M; Hilborn, J; Feitz, W F J; Oosterwijk, E

    2017-09-01

    The design of constructs for tubular tissue engineering is challenging. Most biomaterials need to be reinforced with supporting structures such as knittings, meshes or electrospun material to comply with the mechanical demands of native tissues. In this study, coupled helical coils (CHCs) were manufactured to mimic collagen fiber orientation as found in nature. Monofilaments of different commercially available biodegradable polymers were wound and subsequently fused, resulting in right-handed and left-handed polymer helices fused together in joints where the filaments cross. CHCs of different polymer composition were tested to determine the tensile strength, strain recovery, hysteresis, compressive strength and degradation of CHCs of different composition. Subsequently, seamless and stable hybrid constructs consisting of PDSII® USP 2-0 CHCs embedded in porous collagen type I were produced. Compared to collagen alone, this hybrid showed superior strain recovery (93.5±0.9% vs 71.1±12.6% in longitudinal direction; 87.1±6.6% vs 57.2±4.6% in circumferential direction) and hysteresis (18.9±2.7% vs 51.1±12.0% in longitudinal direction; 11.5±4.6% vs 46.3±6.3% in circumferential direction). Furthermore, this hybrid construct showed an improved Young's modulus in both longitudinal (0.5±0.1MPavs 0.2±0.1MPa; 2.5-fold) and circumferential (1.65±0.07MPavs (2.9±0.3)×10(-2)MPa; 57-fold) direction, respectively, compared to templates created from collagen alone. Moreover, hybrid template characteristics could be modified by changing the CHC composition and CHCs were produced showing a mechanical behavior similar to the native ureter. CHC-enforced templates, which are easily tunable to meet different demands may be promising for tubular tissue engineering. Most tubular constructs lack sufficient strength and tunability to comply with the mechanical demands of native tissues. Therefore, we embedded coupled helical coils (CHCs) produced from biodegradable polymers - to

  13. Microtubes and nanotubes of a phospholipid bilayer membrane

    NASA Astrophysics Data System (ADS)

    Kralj-Iglic, Veronika; Iglic, Ales; Gomiscek, Gregor; Sevsek, France; Arrigler, Vesna; Hägerstrand, Henry

    2002-02-01

    We propose a theory describing the stable structure of a phospholipid bilayer in pure water involving a spherical mother vesicle with long thin tubular protrusion. It is considered that the phospholipid molecules are in general anisotropic with respect to the axis normal to the membrane and can orient in the plane of the membrane if the curvature field is strongly anisotropic. Taking this into account, the membrane free energy is derived starting from a single-molecule energy and using methods of statistical mechanics. By linking the description on the microscopic level with the continuum theory of elasticity we recover the expression for the membrane bending energy and obtain an additional (deviatoric) contribution due to the orientational ordering of the phospholipid molecules. It is shown that the deviatoric contribution may considerably decrease the phospholipid vesicle membrane free energy if the vesicle involves regions where the difference between the two principal curvatures is large (thin cylindrical protrusions and/or thin finite necks) and thereby yields a possible explanation for the stability of the long thin tubular protrusions of the phospholipid bilayer vesicles. We report on the experiment exhibiting a stable shape of the spherical phospholipid vesicle with a long thin tubular protrusion in pure water.

  14. Luminal and basolateral mechanisms involved in the renal tubular uptake of inorganic mercury

    SciTech Connect

    Zalups, R.K.; Minor, K.H.

    1995-09-01

    The present study provides evidence for the existence of both a luminal and a basolateral mechanism involved in the renal tubular uptake of inorganic mercury. The researchers compared the disposition of inorganic mercury in groups of surgical control rats, rats that underwent a unilateral ureteral ligation, and rats that underwent a bilateral ureteral ligation that were pretreated with either normal saline or a 7.5 mmol/kg intravenous dose of PAH 5 min prior to receiving a nontoxic 0.5-{mu}mol/kg intravenous dose of mercuric chloride. The {open_quotes}stop-flow{close_quotes} conditions induced by either unilateral or bilateral ureteral ligation caused a significant reduction in the uptake and content of mercury in the kidneys (whose ureter was ligated) both at 1 h and 24 h after the intravenous injection of the nontoxic dose of mercuric chloride. This decreased renal uptake of mercury was due specifically to decreased uptake of mercury in the renal cortex and outer stripe of the outer medulla. The amount of mercury has not taken up during ureteral ligation represents the portion of mercury that is presumably taken up by a luminal mechanism. Pretreatment with PAH also caused a significant reduction in the renal uptake of mercury in the cortex and outer stripe of the outer medulla. When either unilateral or bilateral ureteral ligation was combined with PAH pretreatment, an additive inhibitory effect occurred with respect to the renal uptake of mercury. In fact, the renal uptake of mercury was reduced by approximately 85% at 1 h after the injection of mercuric chloride. Since the luminal uptake of mercury was blocked by ureteral ligation, the effect of PAH on the renal uptake of mercury must have occurred at the basolateral membrane. Two distinct mechanisms are involved in mercury uptake, with one mechanism located on the luminal membrane and another located on the basolateral membrane. 22 refs., 11 figs., 2 tabs.

  15. 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.

  16. Anodic Aluminum Oxide Membrane-Assisted Fabrication of β-In2S3Nanowires

    PubMed Central

    2009-01-01

    In this study, β-In2S3nanowires were first synthesized by sulfurizing the pure Indium (In) nanowires in an AAO membrane. As FE-SEM results, β-In2S3nanowires are highly ordered, arranged tightly corresponding to the high porosity of the AAO membrane used. The diameter of the β-In2S3nanowires is about 60 nm with the length of about 6–8 μm. Moreover, the aspect ratio of β-In2S3nanowires is up to 117. An EDS analysis revealed the β-In2S3nanowires with an atomic ratio of nearly S/In = 1.5. X-ray diffraction and corresponding selected area electron diffraction patterns demonstrated that the β-In2S3nanowire is tetragonal polycrystalline. The direct band gap energy (Eg) is 2.40 eV from the optical measurement, and it is reasonable with literature. PMID:20596400

  17. Development of bioartificial renal tubule devices with lifespan-extended human renal proximal tubular epithelial cells.

    PubMed

    Sanechika, Noriyuki; Sawada, Kaichiro; Usui, Yukio; Hanai, Kazuya; Kakuta, Takatoshi; Suzuki, Hajime; Kanai, Genta; Fujimura, Satoshi; Yokoyama, Tun Aung; Fukagawa, Masafumi; Terachi, Toshiro; Saito, Akira

    2011-09-01

    The bioartificial renal tubule device is a cell therapy system for renal failure. The major obstacle in the development of the bioartificial renal tubule device is the obtainment of a large number of viable renal tubule cells to seed on the inner surface of hollow fibers. Although our previous studies had used a transformed cell line, they may be dangerous for clinical uses. Therefore, different approaches to amplify renal proximal tubular epithelial cells (RPTEC) in culture without oncogenes, vectors and carcinogens have been required. The limitation of the replicative lifespan of human RPTEC, which is ∼12 population doublings (PDs), was extended by invalidating messenger RNA of cell cycle-related genes with antisense oligonucleotide or small interfering RNA (siRNA). Periodic transfection of siRNA to a tumor suppressor p53 or a cyclin-dependent kinase inhibitor p16(INK4a) extended the lifespan by 33 and 63 PDs, respectively, in 3 months of culture. The siRNA-mediated lifespan extension was controllable because cell division ceased within 2 weeks after the transfection was discontinued. Expressions of γ-glutamyltransferase 1 and glucose transporter 1 were recovered in siRNA-transfected RPTEC cultured on porous membranes. Bioartificial renal tubule devices (0.8 m(2)) constructed with these cells showed reabsorption of water (122.3 ± 4.2 mL/30 min), sodium (18.1 ± 0.7 mEq/30 min) and glucose (121.7 ± 4.4 mg/30 min) after 1 week of circulation. Furthermore, β2-microglobulin and pentosidine were metabolized by RPTEC in mini-devices (65 cm(2)) within 48 h of circulation. These approaches enabled us to yield a high enough number of RPTEC for construction of bioartificial renal tubule devices repeatedly. Lifespan-extended RPTEC could recover their specific characteristics by culturing on porous membranes, and bioartificial renal tubule devices constructed with these cells showed good performances of reabsorption and metabolism. A large number of human renal tubular

  18. Urinary enzymes and low molecular weight proteins as markers of tubular dysfunction.

    PubMed

    Jung, K

    1994-11-01

    Reference intervals of different tubular markers, that is, low molecular weight proteins and urinary enzymes, show divergent data and wide ranges. The problems in establishing reference intervals for the tubular markers are caused by the necessarily different analytical methods. Also, the general rules of determining reference limits as well as the numerous physiological variables influencing tubular function are often not sufficiently taken into consideration. Compared to blood components, urinary tubular markers show a wide variability of values. This is due to the fact that the excretion of enzymes and proteins into urine represents an excretion into an open system. The influences of variables like age, sex, physical exercise, different urine flow rates, and biorhythms are immediately reflected by changed excretion rates of tubular markers. The problems occurring when the second morning urine sample is being used as a "standardized" collection method and the basis to characterize tubular function by analyte/creatinine ratios are discussed in this paper.

  19. Toxicological Significance of Renal Bcrp: Another Potential Transporter in the Elimination of Mercuric Ions from Proximal Tubular Cells

    PubMed Central

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

    2015-01-01

    Secretion of inorganic mercury (Hg2+) 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 Hg2+ 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 Hg2+. To further characterize the role of Bcrp in the handling of mercuric ions and in the induction of Hg2+-induced nephropathy, Sprague-Dawley and Bcrp knockout (bcrp−/−) rats were exposed intravenously to a non-nephrotoxic (0.5 μmol • kg−1), a moderately nephrotoxic (1.5 μmol • kg−1) or a significantly nephrotoxic (2.0 μmol • kg−1) dose of HgCl2. In general, the accumulation of Hg2+ was greater in organs of bcrp−/− rats than in Sprague-Dawley rats, suggesting that Bcrp may play a role in the export of Hg2+ from target cells. Within the kidney, cellular injury and necrosis was more severe in bcrp−/− 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. PMID:25868844

  20. 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.

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

    SciTech Connect

    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. Competitive inhibition of renal tubular secretion of gemifloxacin by probenecid.

    PubMed

    Landersdorfer, Cornelia B; Kirkpatrick, Carl M J; Kinzig, Martina; Bulitta, Jürgen B; Holzgrabe, Ulrike; Drusano, George L; Sörgel, Fritz

    2009-09-01

    Probenecid interacts with transport processes of drugs at several sites in the body. For most quinolones, renal clearance is reduced by concomitant administration of probenecid. The interaction between gemifloxacin and probenecid has not yet been studied. We studied the extent, time course, site(s), and mechanism of this interaction. Seventeen healthy volunteers participated in a randomized, two-way crossover study. Subjects received 320 mg gemifloxacin as an oral tablet without and with 4.5 g probenecid divided in eight oral doses. Drug concentrations in plasma and urine were analyzed by liquid chromatography-tandem mass spectrometry. WinNonlin was used for noncompartmental analysis, compartmental modeling, and statistics, and NONMEM was used for visual predictive checks. Concomitant administration of probenecid increased plasma gemifloxacin concentrations and amounts excreted in urine compared to baseline amounts. Data are average estimates (percent coefficients of variation). Modeling showed a competitive inhibition of the renal tubular secretion of gemifloxacin by probenecid as the most likely mechanism of the interaction. The estimated K(m) and Vmax for the saturable part of renal elimination were 9.16 mg/liter (20%) and 113 mg/h (21%), respectively. Based on the molar ratio, the affinity for the renal transporter was 10-fold higher for gemifloxacin than for probenecid. Since probenecid reached an approximately 200-times-higher area under the molar concentration-time curve from 0 to 24 h than gemifloxacin, probenecid inhibited the active tubular secretion of gemifloxacin. Probenecid also reduced the nonrenal clearance of gemifloxacin from 25.2 (26%) to 21.0 (23%) liters/h. Probenecid inhibited the renal tubular secretion of gemifloxacin, most likely by a competitive mechanism, and slightly decreased nonrenal clearance of gemifloxacin.

  3. Competitive Inhibition of Renal Tubular Secretion of Gemifloxacin by Probenecid▿

    PubMed Central

    Landersdorfer, Cornelia B.; Kirkpatrick, Carl M. J.; Kinzig, Martina; Bulitta, Jürgen B.; Holzgrabe, Ulrike; Drusano, George L.; Sörgel, Fritz

    2009-01-01

    Probenecid interacts with transport processes of drugs at several sites in the body. For most quinolones, renal clearance is reduced by concomitant administration of probenecid. The interaction between gemifloxacin and probenecid has not yet been studied. We studied the extent, time course, site(s), and mechanism of this interaction. Seventeen healthy volunteers participated in a randomized, two-way crossover study. Subjects received 320 mg gemifloxacin as an oral tablet without and with 4.5 g probenecid divided in eight oral doses. Drug concentrations in plasma and urine were analyzed by liquid chromatography-tandem mass spectrometry. WinNonlin was used for noncompartmental analysis, compartmental modeling, and statistics, and NONMEM was used for visual predictive checks. Concomitant administration of probenecid increased plasma gemifloxacin concentrations and amounts excreted in urine compared to baseline amounts. Data are average estimates (percent coefficients of variation). Modeling showed a competitive inhibition of the renal tubular secretion of gemifloxacin by probenecid as the most likely mechanism of the interaction. The estimated Km and Vmax for the saturable part of renal elimination were 9.16 mg/liter (20%) and 113 mg/h (21%), respectively. Based on the molar ratio, the affinity for the renal transporter was 10-fold higher for gemifloxacin than for probenecid. Since probenecid reached an ∼200-times-higher area under the molar concentration-time curve from 0 to 24 h than gemifloxacin, probenecid inhibited the active tubular secretion of gemifloxacin. Probenecid also reduced the nonrenal clearance of gemifloxacin from 25.2 (26%) to 21.0 (23%) liters/h. Probenecid inhibited the renal tubular secretion of gemifloxacin, most likely by a competitive mechanism, and slightly decreased nonrenal clearance of gemifloxacin. PMID:19564368

  4. 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.

  5. Minimally invasive tubular access for posterior cervical foraminotomy

    PubMed Central

    Branch, Byron C.; Hilton, Donald L.; Watts, Clark

    2015-01-01

    Background: Minimally invasive tubular access for posterior cervical foraminotomy can be an effective and safe technique for decompression of the nerve root utilizing minimally invasive muscle splitting with routine outpatient discharge. This technique has come under scrutiny calling into question the associated learning curve, a subjective limited exposure provided, and an argument that the risks and complications are largely unknown. In response to previously published critiques, this study aims to describe the outcomes and complications associated with this technique in a large patient series. Methods: A retrospective chart review was performed from 1999 to 2013 capturing a single surgeon's experience with the minimally invasive tubular access for posterior cervical foraminotomy technique from a single institution, encompassing 463 patients. Surgical outcome documented at follow-up and complications were obtained from this patient series. Additional variables analyzed include: Hospital length of stay, number of levels operated, targeted root for decompression, side operated, length of surgery, and estimated blood loss. Results: Outpatient discharge was achieved in 91.6% of cases. There were 10 complications (2.2%) among the 463 patients undergoing this technique from 1999 to 2013. Patients were followed for an average of 1 year and 2 months postoperatively. Improvement from the preoperative condition was observed in 98.2% of patients and excellent outcomes with patients reporting complete relief of symptoms with no or mild residual discomfort was seen in 92.2%. Conclusions: Compared with open techniques, minimally invasive tubular access for posterior cervical foraminotomy demonstrates comparable, if not superior, complication rates, and patient outcomes. PMID:26009705

  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. Tubular overexpression of gremlin induces renal damage susceptibility in mice.

    PubMed

    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

  8. Computed tomography in suspected osteoid osteomas of tubular bones

    SciTech Connect

    Herrlin, K.; Ekelund, L.; Loevdahl, R.; Persson, B.

    1982-12-01

    Six cases of suspected osteoid osteoma of tubular bones were evaluated by computed tomography (CT). In all cases a radiolucent nidus was clearly demonstrated. In two cases a radiodense center of the nidus was visualized. It is suggested that CT may replace conventional tomography in the evaluation of these lesions. Due to its ability to locate the lesion in the transverse plane, CT is superior for the exact planning of surgery to avoid unnecessary large or misdirected resections. Adequate window settings are essential in the evaluation of these lesions.

  9. Ibuprofen-related renal tubular acidosis in pregnancy.

    PubMed

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

    2011-09-01

    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.

  10. Control system architecture for robotic welding of tubular joints

    SciTech Connect

    Madsen, O.; Holm, H.; Lauridsen, J.K.

    1996-12-31

    This paper presents the architecture of a geometry model and sensor based control system for robotic welding of tubular joints. The functional architecture of the system is described with the main emphasis on the overall mode of operation of the system. Furthermore, it is described how measurements of the physical seam profile are used to update a reference geometry model, and how welding control variables are generated based on the updated reference geometry. Finally, it is illustrated how the use of a reference geometry can improve the flexibility and robustness of the system.

  11. 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.

  12. Tubular Bioreactor for Probing Baculovirus Infection and Protein Production.

    PubMed

    Wu, Hsuan-Chen; Hu, Yu-Chen; Bentley, William E

    2016-01-01

    Probing the baculovirus infection process is essential in optimizing recombinant protein production. Typically, researchers monitor the infection process in stirred reactors that contain cells that have been infected at different times after virus inoculation, particularly if cells pass the primary infection and become infected by progeny virus. This chapter describes several alternative bioreactor systems for baculovirus infection. We provide an example alternative system that holds promise to avoid asynchronous distributions in infection time. Namely, we describe a two-stage reactor system consisting of an upstream continuous stirred tank reactor and a downstream tubular reactor with segmented plug flow for probing baculovirus infection and production.

  13. Performance of tubular members under cyclic axial loads

    SciTech Connect

    Shaker, R.E.; Murakawa, Hidekazu; Ueda, Yukio

    1995-12-31

    In this paper the behavior of pin-ended tubular steel members under cyclic axial loads is studied by using Finite Element Method (FEM) considering both geometrical and material non-linearities. The factors considered in this study are the cyclic loading characteristics (displacement amplitude and mean displacement), geometrical parameters (diameter-to-thickness ratio D/t and normalized slenderness ratio {lambda}) and inelastic characteristics of the material. The results of numerical analysis are closely examined with respect to both ultimate strength and energy dissipation capacity.

  14. Hyperammonaemia in a child with distal renal tubular acidosis.

    PubMed

    Seracini, D; Poggi, G M; Pela, I

    2005-11-01

    A 5-month-old girl with distal renal tubular acidosis (RTA) and hyperammonaemia that had lasted for 12 days, despite metabolic acidosis correction, is presented in this report. The patient showed failure to thrive, poor feeding, hypotonia and vomiting crisis in absence of inborn errors of metabolism. Probably, hyperammonaemia was the result of an imbalance between the increased ammonia synthesis, in response to metabolic acidosis, and the impaired ammonia excretion, typical of distal RTA. Our case confirms that hyperammonaemia may be observed in distal RTA, mimicking an inborn error of metabolism, and it underlines that hyperammonaemia may persist several days after metabolic acidosis correction.

  15. Functionalization of polycarbonate with proteins; open-tubular enzymatic microreactors.

    PubMed

    Ogończyk, D; Jankowski, P; Garstecki, P

    2012-08-07

    This paper examines a set of techniques for the immobilization of enzymes on the surface of microchannels fabricated in polycarbonate (PC). Our experiments identify the method that uses combined physico-chemical immobilization on a layer of polyethyleneimine (PEI) as a reproducible vista for the robust immobilization of proteins. As an example, we demonstrate the fabrication, throughput and stability of an open-tubular reactor draped with alkaline phosphatase (ALP, EC 3.1.3.1) as a model enzyme. As PC is suitable for industrial applications the method could potentially be used to immobilize proteins in numbered-up implementations.

  16. Giant Candida mycetoma in an ascending aorta tubular graft.

    PubMed

    Di Benedetto, Giuseppe; Citro, Rodolfo; Longobardi, Antonio; Mastrogiovanni, Generoso; Panza, Antonio; Iesu, Severino; Bossone, Eduardo

    2013-09-01

    We report the case of a 46-year-old male hospitalized for abdominal pain and fever with history of a David procedure followed by an aortic valve replacement due to severe aortic regurgitation. Transesophageal echocardiography (TEE) and computed tomography showed a large mass floating in the aorta. After surgical excision of the vegetation, attached to the Dacron prosthesis, histological examination revealed Candida hyphae and spores confirming the diagnosis of a mycetoma in an ascending aorta tubular graft. At six-month follow-up, the patient was in good clinical condition without recurrence of the fungal mass on TEE. © 2013 Wiley Periodicals, Inc.

  17. Lethal activity of FADD death domain in renal tubular epithelial cells.

    PubMed

    Justo, P; Sanz, A B; Lorz, C; Egido, J; Ortiz, A

    2006-06-01

    Fas-associated death domain (FADD) is an adaptor protein that is required for the transmission of the death signal from lethal receptors of the tumor necrosis factor superfamily. FADD contains a death domain (DD) and a death effector domain (DED). As death receptors contribute to renal tubular injury and tubular cell FADD increases in acute renal failure, we have studied the function of FADD in tubular epithelium. FADD expression was studied in kidney samples from mice. In order to study the contribution of FADD to renal tubular cell survival, FADD or FADD-DD were overexpressed in murine tubular epithelium. FADD is expressed in renal tubules of the healthy kidney. Both FADD and FADD-DD induce apoptosis in primary cultures of murine tubular epithelium and in the murine cortical tubular cell line. Death induced by FADD-DD has apoptotic morphology, but differs from death receptor-induced apoptosis in that it is not blocked by inhibitors of caspases. Neither an inhibitor of serine proteases nor overexpression of antiapoptotic BclxL prevented cell death. However, the combination of caspase and serine protease inhibition was protective. FADD and FADD-DD overexpression decreased nuclear factor kappa B activity. These data suggest that FADD has a death regulatory function in renal tubular cells that is independent of death receptors. FADD-DD is sufficient to induce apoptosis in these cells. This information is relevant to understanding the role of FADD in tubular injury.

  18. Expression of cleaved caspase-3 in renal tubular cells in Plasmodium falciparum malaria patients.

    PubMed

    Wichapoon, Benjamas; Punsawad, Chuchard; Viriyavejakul, Parnpen

    2017-01-01

    In Plasmodium falciparum malaria, the clinical manifestation of acute kidney injury (AKI) is commonly associated with acute tubular necrosis (ATN) in the kidney tissues. Renal tubular cells often exhibit various degrees of cloudy swelling, cell degeneration, and frank necrosis. To study individual cell death, this study evaluates the degree of renal tubular necrosis in association with apoptosis in malarial kidneys. Kidney tissues from P. falciparum malaria with AKI (10 cases), and without AKI (10 cases) were evaluated for tubular pathology. Normal kidney tissues from 10 cases served as controls. Tubular necrosis was assessed quantitatively in kidney tissues infected with P. falciparum malaria, based on histopathological evaluation. In addition, the occurrence of apoptosis was investigated using cleaved caspase-3 marker. Correlation between tubular necrosis and apoptosis was analyzed. Tubular necrosis was found to be highest in P. falciparum malaria patients with AKI (36.44% ± 3.21), compared to non-AKI (15.88% ± 1.63) and control groups (2.58% ± 0.39) (all p < 0.001). In the AKI group, the distal tubules showed a significantly higher degree of tubular necrosis than the proximal tubules (p = 0.021) and collecting tubules (p = 0.033). Tubular necrosis was significantly correlated with the level of serum creatinine (r = 0.596, p = 0.006), and the occurrence of apoptosis (r = 0.681, p = 0.001). In malarial AKI, the process of apoptosis occurs in ATN. © 2016 Asian Pacific Society of Nephrology.

  19. A comparison of acute hospital charges after tubular versus open microdiskectomy.

    PubMed

    Cahill, Kevin S; Levi, Allan D; Cummock, Matthew D; Liao, Wensheng; Wang, Michael Y

    2013-01-01

    To determine if tubular microdiskectomy is associated with differences in hospital charges compared with open microdiskectomy. A retrospective review of patients who underwent tubular microdiskectomy or open microdiskectomy performed by the senior authors from 2007-2010 was performed. The primary outcome was inflation-adjusted total hospital charges for each procedure using itemized charge data obtained from the hospital finance department. Secondary outcomes included length of stay, complications, and operative times. There were 76 eligible patients (33 open microdiskectomy and 48 tubular microdiskectomy) identified during the study period. The mean total charge was $27,811 (standard deviation $11,198) in the open group compared with $22,358 (standard deviation $8695) in the tubular group. Total charges in the tubular group were on average $5453 less than in the open group (P = 0.02). There were no significant differences in operative times or complications. Length of stay was significantly shorter in the tubular group (mean 1.5 days open vs. 0.9 days tubular, P = 0.01). This analysis revealed significantly lower acute hospital charges associated with tubular microdiskectomy versus open microdiskectomy at an academic tertiary care hospital. These differences appear to the related to decreased use of postoperative resources in the tubular group. Copyright © 2013. Published by Elsevier Inc.

  20. Vibration analysis and sound field characteristics of a tubular ultrasonic radiator.

    PubMed

    Liang, Zhaofeng; Zhou, Guangping; Zhang, Yihui; Li, Zhengzhong; Lin, Shuyu

    2006-12-01

    A sort of tubular ultrasonic radiator used in ultrasonic liquid processing is studied. The frequency equation of the tubular radiator is derived, and its radiated sound field in cylindrical reactor is calculated using finite element method and recorded by means of aluminum foil erosion. The results indicate that sound field of tubular ultrasonic radiator in cylindrical reactor appears standing waves along both its radial direction and axial direction, and amplitudes of standing waves decrease gradually along its radial direction, and the numbers of standing waves along its axial direction are equal to the axial wave numbers of tubular radiator. The experimental results are in good agreement with calculated results.